hydrocarbon source rock variability within the austin chalk and eagle ford shale upper cretaceous east texas u s a abstract the austin chalk and eagle ford shale are upper cretaceous deposits that extend across texas from the northeast to southwest these formations contain organic carbon enriched mudstones and chalks that were deposited during transgressions of the cretaceous epeiric sea in north america recent workers in petroleum geochemistry have demonstrated that these organic enriched rocks possessed attributes common to oil source rocks the present study of these austin chalk and eagle ford shale rocks is from the perspective of organic petrology and it augments the earlier geochemical work that documented source variability within units of these formations as with the earlier work the results of this study show that both formations contain intervals that are when mature capable of generating commercial quantities of liquid hydrocarbons however this work further revealed that eagle ford rocks not only exhibit greater or ganic carbon contents but also have greater quantities of oil prone kerogen fluorescent amorphinite and exinite when compared with rocks from the austin chalk these source rock differences relate to levels or degrees of organic preservation dysaerobic to oxic depositional settings seem to be more characteristic of the austin chalk than of the eagle ford shale such oxic environments do not consistently favor the preservation of organic matter usually well preserved kerogen forms under more anoxic conditions such as those that occurred during deposition of some eagle ford units these anoxic conditions suggest that the geographically more extensive eagle ford shale is a more important source for oil than is the austin chalk

extreme monsoon aridity episodes recorded in south china during heinrich events geological records of climate change since the last glaciation in south china a core area of the east asian monsoon are key to understanding secular variation in the monsoon system however with the exception of the speleothems records from this area with independent age control are few we investigated aeolian sand deposition on a sand hill on the shore of poyang lake in south china and reconstructed the chronological sequence of aeolian deposition using optically stimulated luminescence osl dating without exception all aeolian sediments were deposited within seven periods that generally match the timing of heinrich events and other cold periods in greenland we argue that aeolian sand accumulation in this region is most likely forced by extreme aridity driven by weakening of the summer monsoon while the characteristics of this deposition are influenced by winter monsoon intensity the monsoon shifts revealed here suggest a possible link between north atlantic cooling and summer monsoon strength in south china and support the intensities of cooling phases recorded in greenland ice cores

high thermal maturity in the lower saxony basin intrusion or deep burial abstract the lower saxony basin lsb is situated at the southern rim of the northern permian basin the most important hydrocarbon bearing province in europe in its southern part areas of high thermal maturation up to 6 rr occur which were previously explained as being caused by magmatic intrusions of turonian to santonian age that affected carboniferous to lower cretaceous rocks in this area 2d numerical basin modelling was carried out in order to reconstruct the temperature histories along two parallel n s trending seismic sections along these sections new data about maturity distribution and temperature history were obtained by vitrinite reflectance measurements and apatite fission track analysis for the areas with highest maturity values low coalification gradients were established which agree well with earlier published data on wells further towards the west this new information does not support previous hypotheses on high heat flows from magmatic intrusions even if lateral heat transport is taken into account instead comparisons with a recently published map of the subsurface structure of the lsb indicate that maturity distribution may be closely related to major tectonic structures deep burial of individual structures of the lsb which are bordered by deep e w to ese wnw trending faults is further suggested by a rapidly increasing thicknesses of preserved cretaceous strata towards the south and b structural restoration of one of the seismic sections to achieve a fit between measured and calculated palaeo temperature and vitrinite reflectance data deep burial of carboniferous source rocks during cretaceous time has to be assumed due to an inversion phase in the early and middle upper cretaceous major amounts of sediment were removed and further uplift occurred in tertiary times in contrast the northern part of the lsb experienced maximum burial and temperatures during tertiary times

how ice age climate got the shakes records in greenland ice ocean mud and ancient corals are revealing abrupt climate shifts during the last ice age the climate at the end of the last ice age apparently jumped from cold to warmer conditions jumped back to cold and then jumped into the present warm weather conditions the mechanism for this erratic behavior is unknown but appears to be an interaction of north atlantic ocean currents and the ice sheets themselves warm water from the tropics would evaporate and become more saline and dense as it moved north the colder denser water would then sink and flow back to the tropics the melting of ice caused by the warm water would decrease the salinity of the north atlantic current the water would not sink the return current would be shut down and the waters surrounding the ice sheets would become colder slowing melting of the sheets the cycle could be started again by collapse of the ice sheets from their internal heat there may be other switches that could cause sudden climate change as may be evidenced by links between changes in the pacific and a decade of erratic weather in north america researcher would like to identifymore these switches to prevent them from being activated by human activity less

major bounding surfaces in aeolian sandstones a climatic model large areas of fixed vegetated dunes occur in the sahel and southern margin of the sahara these dunes were active during late pleistocene times and have been stabilized as a result of a change to more humid less windy conditions in the holocene the stabilized surfaces which are in part of erosional origin are of regional extent within aeolian sand sequences such surfaces form the highest order bounding surfaces since regional bounding surfaces of this type occur in all the world s major deserts it is suggested that they should also be present in some ancient aeolian sandstone sequences

the flickering switch of late pleistocene climate change polar ice contains a unique record of past climate variations previous greenland ice cores have documented relatively warm interstadial periods during the last glaciation and short centuryscale returns to colder conditions during the glacial to interglacial warming see for example ref 1 these climate features have also been observed to varying degrees in ocean sediment cores2 4 and terrestrial pollen and insect records5 7 here we report electrical conductivity measurements from a new greenland ice core which confirm these previous observations and also reveal a hitherto unrecognized mode of rapid climate variation fluctuations in ice conductivity on the scales of 5 20 years reflect rapid oscillations in the dust content of the atmosphere this flickering between two preferred states would seem to require extremely rapid reorganizations in atmospheric circulation

significance of interdune deposits and bounding surfaces in aeolian dune sands bounding surfaces and interdune deposits provide keys for detailed interpretations of the development shape type wavelength and angle of climb of aeolian bedforms as well as overall sand sea conditions current alternate interpretations of bounding surfaces require very different but testable models for sand sea deposition two perpendicular traverses of jurassic entrada sandstone utah reveal relations among cross strata first order bounding surfaces and horizontal strata these field relations seem explicable only as the deposits of downwind migrating climbing enclosed interdune basins horizontal strata and dune bodies consisting of superimposed smaller crescentic dunes cross stratified deposits a 1 7 km traverse parallel to the palaeowind direction provides a time transgressive view showing continuous cosets of cross strata first order bounding surfaces and interdune deposits climbing downwind at an angle of a few tenths of a degree changes occur in the angle of climb cross strata structure and interdune deposits these reflect changes in depositional conditions through time a 1 5 km traverse perpendicular to the palaeowind direction provides a view at an instant in geological time showing first order bounding surfaces and interdune deposits forming flat laterally discontinuous lenticular bodies the distribution of interdune sedimentary structures in this traverse is very similar to that of some modern interdune basins such as those on padre island texas hierarchies of bounding surfaces in an aeolian deposit reflect the bedform development on an erg the presence of three orders of bounding surfaces indicates dune bodies consisting of smaller super imposed dunes the geometry of first order bounding surfaces is a reflection of the shape of the inter dune basins second order bounding surfaces originate by the migration of the superimposed dunes over the larger dune body and reflect individual dune shape and type third order bounding surfaces are reactivation surfaces showing stages in the advance of individual dunes the presence of only two orders of bounding surfaces indicates simple dunes modern and entrada interdune deposits show a wide variety of sediment types and structures reflecting deposition under wet damp and dry conditions interdune deposits are probably the best indicators of overall erg conditions and commonly show complex vertical sequences reflecting changes in specific depositional conditions

non linear body wave teleseismic tomography along the tor array summary the tor project investigates the lithosphere asthenosphere structure under the tornquist zone between denmark and sweden around 150 seismic stations 108 short period 28 broadband and 14 other permanent stations were employed in a rectangular array along a 900 km long by 100 km wide strip across the tornquist zone from july 1996 to august 1997 the results obtained based on a non linear teleseismic tomography algorithm reveal significant p velocity variations up to 5 per cent along the tor array from northern germany to southern sweden distinct lithospheric blocks are also recognized in the inversion results two inverse methods singular value decomposition and a quadratic programming method were implemented in order to investigate whether or not the lithospheric blocks and major boundaries in the inversion are required by the data or are artefacts of the inversion according to the results the lithosphere under northern germany is thin but reaches to intermediate thicknesses of about 120 km in the tornquist zone area farther north in the baltic shield more than 200 km of continental lithosphere is recognized in the model abrupt lateral p velocity changes maximum 5 per cent are seen at both the southern and northern sides of the tornquist zone

geologic time series from deep sea sediments time scales and distortion by bioturbation abstract in order to evaluate the time and frequency domain characteristics of geologic time series obtained from deep sea sediments two important problems must be considered first an accurate time scale must be established for the sediment records to be studied an accurate time scale is a basic requirement for such techniques as spectral and cross spectral analysis secondly the distortion of a geologic time series by sedimentation processes such as bioturbation must be considered if inferences are to be made about the mechanisms controlling climatic and oceanographic processes reflected in the geologic record recently it has been suggested that the periodic components in paleoclimatic records which can be related to variations in the earth s orbital parameters can be used as a means for providing very detailed control for late pleistocene sediment sections a time scale is estimated by tuning an individual frequency component in a climate record to an orbital parameter the tuning procedure commonly uses the technique of bandpass filtering which removes all frequency components except the one equivalent to an orbital parameter and then adjusting the geologic time scale so that the filtered record and orbital record align since bandpass filtering will produce a periodic record from any data set a question is raised as to the circularity of this tuning approach a series of numerical experiments using synthetic time series are used to determine if the tuning of a geologic record artificially induces improved correlation and increased periodic character in a climatic record these experiments indicate that the tuning does not artificially induce these effects thus it is suggested that the careful use of orbital tuning provides a powerful means of defining a geologic time scale the degree to which bioturbation distorts a paleoclimatic record is studied by comparing the spectra of oxygen isotopic records obtained from cores with sedimentation rates ranging from 1 to 12 cm 1000 yr 1 it is shown that the systematic change in the variance spectra of these records that is predicted by models of bioturbation cannot be observed for sedimentation rates greater than 2 cm 1000 yr 1 this can be explained in part if bioturbation is a function of sedimentation rates if this is the case then bioturbation must proceed to depth of tens to hundreds of centimeters however it seems likely that the degree to which bioturbation alters the climate signal preserved in deep sea sediment cores has been overestimated

late quaternary aeolianites palaeosols and depositional environments on the nepean peninsula victoria australia abstract the nepean peninsula is a bay mouth bar near melbourne it is comprised of late quaternary aeolianites palaeosols and calcretes tl dates show that most of the sands from which the aeolianites developed as mobile sand dunes were deposited during times of low sea level towards 47 and 23 ka bp and others during times of relatively high sea level towards 118 ka bp aeolian dust mantles were laid down during brief intervals when aeolianite formation had ceased incipient soil formation and minor organic staining of the upper 0 3 0 5 m of the dust mantles points to a lull in dune formation and the temporary development of a widespread plant cover the dust mantles have tl ages of 118 57 54 51 and 47 ka bp indicating that apart from the 118 ka mantle most of the deposition was when sea level was low and the regional climate was drier windier colder and under a more continental climatic regime during times of glacially lower sea level the coastal climate in this region was not invariably cold dry and windy but was punctuated by brief intervals of milder moister and less windy conditions during which dunes and dust mantles became vegetated and soils began to form rapid climatic fluctuations were coeval with aeolianite deposition during times of very low sea level

man and environment in the marsh area of schleswig holstein from roman until late medieval times abstract reconstruction of coastal development environment and settlement history is one of the main objectives of coastal archaeology in schleswig holstein the fieldwork program concentrated until 1975 on the excavation of dwelling mounds and after that on the reconstruction of the landscape and settlement history of large areas cultural elements of the coastal area were mapped in several surveys integrating archaeological geological and palaeobotanical aspects on the island of sylt archsum project in the north frisian tidal flats norderhever project on the eiderstedt penisula and in dithmarschen according to this kind of research environmental changes dominated the settlement history and settlement pattern in the 1st millennium ad archaeological finds and excavations indicate that the earliest coastal settlements were founded in the salt marshes of schleswig holstein in the early roman period in dithmarschen as well as in the southern part of eiderstedt the river marshes and salt marshes were densely populated during this period in the 1st and 2nd century ad the inhabitation of the area took place in a phase of lowering of the sea level the settlements were erected on the natural surface of the coastal marshland preferably on elevated areas thereafter a rising sea level and intensified flooding led to the abandonment of some settlements at other localities the inhabitants protected themselves against the storm surges by the construction of dwelling mounds so called wurten the first phase of inhabitation of the coastal marshland ended at about ad 450 a second phase of inhabitation of the coastal marshes began in the middle or late 7th century ad it started with new settlements on the natural land surface of the marshland and was followed by as second phase of wurt construction the present day north frisian tidal flat area was covered with extended peat bogs and could not be inhabited before high medieval times starting with this period the natural landscape changed to a cultural landscape cooperatives of peasants and the parishes played an important role in this process dikes were built and deep seated areas were drained and cultivated in the late middle ages catastrophic storm floods had terrible effects the sea destroyed large parts of the north frisian utlande remnants of this period like warften dikes field pattern and churches are still visible in the present day tidal flats the unfavourable combination of human activities peat cutting for salt production and natural geological processes was responsible for the catastrophic floods of late medieval times cultural monuments of this evolution are still preserved in the coastal landscape the protection of the cultural heritage is of high value for the future

episode of strengthened summer monsoon climate of younger dryas age on the loess plateau of central china abstract the baxie loess section just east of the tibetan plateau contains evidence showing that the asian monsoon climate experienced an abrupt reversal near the end of the last glacial age rapid deposition of dust under cool dry full glacial conditions gave way to an interval of soil development and reduced dust influx attributed to a strengthening of the warm moist summer monsoon a subsequent abrupt increase in dust deposition a response to a weakening of the summer monsoon was later followed by renewed soil formation as summer monsoon circulation again intensified during the early holocene by one interpretation the thin upper loess is a manifestation of the european younger dryas oscillation however in this case the available 14c ages require either that 1 onset of loess deposition lagged the beginning of the younger dryas event in europe by as much as 2000 calibrated 14c years or 2 all the 14c ages are too young possibly due to contamination alternatively the late glacial paleosol the top of which is synchronous with the abrupt end of the late glacial 18o anomaly in the dye 3 greenland ice core records the younger dryas event such an interpretation is consistent with general circulation model simulations of younger dryas climate that show strong seasonality and a strengthened summer monsoon and with marine cores from the western pacific ocean that contain evidence of pronounced cooling of surface waters during younger dryas time

crustal structure along the central segment of the egt from seismic refraction studies abstract the seismic refraction line between the gulf of genova and the baltic sea was carried out in 1986 as part of the european geotraverse egt 86 the central segment of the egt also known as eugemi european geotraverse middle part has a total length of 825 km and runs from the northern margin of the alps to the baltic sea traversing mainly the variscan mountain area of western germany the p wave data of nine shotpoints were interpreted in detail and a two dimensional p velocity model of the crust was developed between the molasse basin and the southern end of the north german basin for the north german basin the data quality justifies only the construction of a simplified model the internal crustal structure is quite complex in the upper crust of the moldanubian and saxothuringian zones of the variscan orogen the velocities are lower than in the rhenohercynian area the velocity of 6 0 km s representing consolidated seismic basement is reached at depths of as much as 10 12 km northern margin of alps and north german basin and of only 3 km under the mid german crystalline rise mid crustal velocities range from 5 8 to 6 1 km s forming weak velocity reversals in some parts in the lower crust velocities as low as 6 2 km s are seen near the alps in contrast to velocities between 6 8 and 7 2 km s in the exposed variscan orogen north of shotpoint e between hannover and the river elbe the velocity of the lower crust is about 6 4 km s north of the elbe line it increases abruptly to 6 9 km s the crust mantle boundary rises from 34 km depth under the northern margin of the alps to 29 km under the swabian jura under the variscan orogen to the north the crustal thickness varies only slightly around an average depth of about 29 1 k but drops to about 30 km under the north german basin between the elbe line and the ringkobing fyn high the moho rises to a depth of about 26 km and the data indicate at least one fault like step of 1 km before the crust thickens toward the basement high the velocities in the uppermost mantle show considerable variation the highest velocity of 8 4 km s is observed beneath the saxothuringian zone and the lowest values of 7 8 7 9 km s are recorded under the hessen depression

the post glacial landscape evolution of the north german basin morphology neotectonics and crustal deformation the recent evolution of the north german basin ngb which is presently a low seismic area was partly affected by glacial loading and unloading of the ice masses major stresses acting within the ngb are induced by the north atlantic ridge push the ongoing alpine collision and the post glacial rebound of fennoscandia present day horizontal stresses within the ngb are directed generally nw se but fan and bend north of 52 n towards nne major basement faults are directed nw se minor faults ne sw and nne ssw and are clearly detectable in geomorphological and satellite lineaments furthermore the drainage pattern and the distribution of lakes in northern germany follow exactly block boundaries and hence mark zones of present day subsidence the understanding of the post glacial morphology and reactivation of faults requires a view into the very heterogeneous crust and upper mantle below the ngb the re adjustment of the individual fault blocks during post glacial relaxation of the lithosphere leads to differential crust dependent uplift and probably to the formation of urstrom valleys the urstrom valleys and terminal moraines in northern germany appear to parallel the major tectonic lineaments and lithospheric block boundaries the lithospheric memory is expressed in the post glacial landscape evolution of the ngb

intense earthquakes and seismotectonics as a function of glacial isostasy abstract old shields and plate interiors have often been assumed to exhibit a high crustal stability during the last decade or two we have learnt more and more about the fragility not to say untenability of this concept however high magnitude earthquakes and large scale fault movements have been recorded where they were not supposed to be able to occur within formerly glaciated areas like northern europe scotland and northern north america a rapidly increasing number of field observations indicates that the glacial isostatic readjustment process was linked to intense seismotectonic activity we will here investigate the fennoscandian situation and propose a novel causation model for the high deglaciation seismicity in comparison with the present day situation

the long term paleomonsoon variation recorded by the loess paleosol sequence in central china abstract the loess paleosol sequence in central china during the last 2 5 ma is a good record of the asian monsoon variation which could be considered as the concrete realization of global paleoclimatic cycles the geological and biological evidence of the loess paleosol sequence indicates that the loess was mainly the dust deposits transported by the northerly wind of winter monsoons and also suffered to some extent from pedogenesis caused by weakened summer monsoons and that the paleosol accreted by the rather slow dust accumulation was closely related to strengthened summer monsoons an alternating occurrence of loess and paleosol in the luochuan section implies the variation history of warm humid climate with a summer monsoon dominance and cold dry climate with a winter monsoon dominance the magnetic susceptibility of loess and paleosol can be regarded as a proxy index of asian monsoon variation an analysis of the susceptibility curve and structure characters of luochuan section shows that the asian monsoon circulation was strengthened from early pleistocene to late pleistocene and the 500 ka bp point and 1200 ka bp point seem to be a threshold and a turning point respectively in terms of the long term paleomonsoon variation in asia

strike slip tectonics within the sw baltic sea and its relationship to the inversion of the mid polish trough evidence from high resolution seismic data abstract the sw baltic sea occupies an area where crustal scale regional tectonic zones of different age merge and overlap creating a complex tectonic pattern this pattern influenced the evolution of the mesozoic sedimentary basin in this area we present an interpretation of new high resolution seismic data from the sw baltic sea which provided new information both on modes of the late cretaceous inversion of this part of the danish polish mesozoic basin system as well as on relationship between tectonic processes and syn tectonic depositional systems within the bornholm darlowo fault zone located between the koszalin fault and christianso block both strike slip and reverse faulting took place during the inversion related activity the faulting was related to reactivation of extensional pre permian fault system syn tectonic sedimentary features include a prominent generally s and se directed progradational depositional system with the major source area provided by uplifted basement blocks in particular by the bornholm block sediment progradation was enhanced by downfaulting along a strike slip fault zone and related expansion of accommodation space closer to the christianso block some syn tectonic deposition also took place and resulted in subtle thickness changes within the hinge zones of inversion related growth folds lack of significant sediment supply from the inverted and uplifted offshore part of the mid polish trough suggests that in this area nw se located marginal trough parallel to the inversion axis of the mid polish trough did not form and that uplifted bornholm block played by far more prominent role for development of syn inversion depositional successions

geochemical evidence for provenance diversity of loess in southern china and its implications for glacial aridification of the northern subtropical region abstract the thick xiashu loess in southern china is distributed not only in the yangtze river valley but also and most extensively in the region between the qinling mountains and the lower reaches of the yangtze river however there are few studies of the provenance and climatic implications of the xiashu loess in this latter region here we present the results of a provenance study of last glacial loess samples from twenty two typical xiashu loess sections using the major and trace element composition as a provenance indicator seventeen of the sites are located to the north of the yangtze river and our primary aim was to determine the provenance of the xiashu loess within this region our results indicate that the alluvial plain located mainly in the present drainage area of the huai river was the primary dust source for the xiashu loess in this region the occurrence of multiple local dust sources within this alluvial plain suggested by their geochemical heterogeneity indicates that the alluvial plain experienced intensified aridity which caused it to become a dust source for local loess deposits in northern subtropical china during the last glacial our study provides strong evidence to challenge the long held view that the occurrence of xiashu loess resulted from the southward incursion of the clp loess deposits sourced from deserts of the asian interior and it confirms the substantial role of aridification of the present humid northern subtropical region for dust emission to the climate system during the last glacial

the bifrost project gps determined 3 d displacement rates in fennoscandia from 800 days of continuous observations in the swepos network abstract this presentation summarizes results obtained from 800 days of operation of swepos the swedish permanent gps array located in the area of the fennoscandian land uplift swepos is the main measuring device for the bifrost project aiming primarily at determination of crustal motions and changes in global sea level in conjunction with postglacial rebound as a future prospect the project will contribute to determine present day changes in the oceanic water budget as well as strive for a more complete understanding of the viscoelastic structure of crust and mantle we show solutions of site positions obtained from the daily processing of the gps observations we determine their variations in time discerning them from plate or frame orientation and discuss a number of perturbation effects among these the possibility of random walk monument motion is considered the feasibility of single site solutions rather than baseline pairs is demonstrated on the basis of 800 days of operation of the permanent network data analysis is able to confirm the general rebound pattern comparison with both modelling results and evidence from mareograph and precise levelling shows high rates of vertical surface displacement from gps measurements in the centre of the pleistocene glaciation region we discuss the possibility of rate biases due to problems with the terrestrial reference frames

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

an estimate of the stress tensor in sweden using earthquake focal mechanisms abstract an estimate of the state of stress in sweden is made by inversion of the fault plane solutions of naturally occurring earthquakes it is shown that the stress state in southern sweden is significantly different from that in northern sweden in southern sweden the principal compression is in a roughly nw se direction similar to that prevailing in northwest europe as a whole this stress direction is is consistent with the stresses expected on the basis of motions of the major tectonic plates in northern sweden however there is no strongly dominant stress direction this latter observation is consistent with a situation in which processes other than first order plate motions are important the most likely explanation in this case is the effect of the deglaciation of fennoscandia which is producing rates of rebound as high as 9 mm year in northern sweden

suppression of earthquakes by large continental ice sheets the interior regions of antarctica and greenland are aseismic no earthquake larger than body wave magnitude 4 5 5 0 is known for either except along coastal zones or continental shelves here i advance an explanation for this lack of seismic activity in terms of pressure effects produced by the continental ice sheets that mantle both continents

the sedimentary record and rates of quaternary vertical tectonic movements in nw poland abstract analysis based on drilling lithostratigraphic geophysical and geodetic data showed that the spatial differentiation pattern of the pleistocene cover displays a direct connection with the structural pattern of the permo mesozoic complex the main features of the pleistocene cover such as the thickness stratigraphic section facies variability and the shape of the sub quaternary surface are adapted to the distribution of local permo mesozoic tectonic elements salt tectonic folds grabens and singular blocks this is expressed by a reduction in the thickness and stratigraphic section of pleistocene sediments overlying uplifted tectonic elements in relation to those which were lowered facies variability within the pleistocene complex is in many places connected with the location of salt tectonic folds and this connection is manifested by the gradual disappearance of water laid series over salt anticlines the most intensive isostatically driven vertical displacements occurred during the cromerian holsteinian and eemian interglacial periods transformation of repeated levelling data allowed the velocity of recent vertical displacements between examined tectonic elements to be estimated at 0 3 2 0 mm yr and this is comparable to the velocity of pleistocene movements the pleistocene displacements between tectonic elements exerted a decisive influence on the development of their glaciogenic sedimentary cover

regional patterns of tectonic stress in europe nearly 1500 stress orientation determinations are now available for europe the data come from earthquake focal mechanisms overcoring measurements well bore breakouts hydraulic fracturing measurements and young fault slip studies and sample the stress field from the surface to seismogenic depths three distinct regional patterns of maximum compressive horizontal stress shmax orientation can be defined from these data a consistent nw to nnw shmax stress orientation in western europe a wnw ese shmax orientation in scandinavia similar to western europe but with a larger variability of shmax orientations and a consistent e w shmax orientation and n s extension in the aegean sea and western anatolia the different stress fields can be attributed to plate driving forces acting on the boundaries of the eurasian plate locally modified by lithospheric properties in different regions on average the orientation of maximum stress in western europe is subparallel to the direction of relative plate motion between africa and europe and is rotated 17 clockwise from the direction of absolute plate motion the uniformly oriented stress field in western europe coincides with thin to medium lithospheric thickness approximately 50 90 km and high heat flow values 80 m w m2 in western europe a predominance of strike slip focal mechanisms implies that the intermediate principal stress is vertical the more irregular horizontal stress orientations in scandinavia coincide with thick continental lithosphere 110 170 km and low heat flow 50 m w m2 the cold thick lithosphere in this region may result in lower mean stresses associated with far field tectonic forces and allow the stress field to be more easily perturbed by local effects such as deglaciation flexure and topography the stress field of the aegean sea and western anatolia is consistent with n s extension in a back arc setting behind the hellenic trench subduction zone the stress field is influenced in places by regional geologic structures e g in the western alps where shmax directions show a slight tendency toward a radial stress pattern not all major geologic structures however appear to affect the shmax orientation e g in the vicinity of the rhine rift system horizontal stress orientations are continuous

the last glacial stratigraphic sequence depositional environment and climatic fluctuations from the aeolian sand dune in hongguang pengze jiangxi china abstract the hongguang sand hill is located along the south bank of the yangtze river in pengze county jiangxi province china rising more than 50 m above the ground it consists of aeolian sand beds interbedded with 11 relatively thin palaeosols the aeolian sand beds include dune deposited cross stratified sand beds and interdune deposited horizontally stratified sand beds both being well sorted the 11 palaeosols are numbered as z 1 to z 11 from bottom to top in chronological order among them 10 palaeosols z 2 to z 11 are dark brown soils while z 1 includes black to very dark grey lenses of peaty soil which change laterally into dark brown soil a hierarchy of bounding surfaces as summarized by kocurek 1988 can be recognized in the sand hill including super surfaces namely palaeosols first and third order bounding surfaces the formation of palaeosols represents hiatuses between aeolian sand depositions and suggests a climatic change from arid to more humid conditions 14 c dates show that the sequence from z 1 to z 7 was formed between about 26 000 and 20 000 bp indicating that each cycle from the aeolian sands to palaeosol that is each arid to humid climatic shift spent an average term of about 1000 a analysis of sedimentary features of the sand hill shows that the aeolian sand grains were mainly from the palaeo yangtze river which was probably an intermittent river during the dune development discussion is also made on the possible palaeoclimatic linkage between the hongguang area and the north atlantic region during the last glaciation

correlation between climate events in the north atlantic and china during the last glaciation episodes of massive iceberg release heinrich events 1 3 into the north atlantic ocean during the last glaciation were associated with recurring episodes of unusually cold north atlantic surface water bond cycles 4 and cold air temperatures over greenland dansgaard oeschger events 5 6 four of the youngest of these cold events have also been reported in climate records from sites outside the north atlantic region7 but until now the entire suite has been identified only in north atlantic marine sediments greenland ice core records and tentatively in french lake sediments8 here we examine grain size data from chinese loess and intercalated accretionary palaeosols of last glacial age for evidence of similar climate signals remote from the north atlantic region we see grain size maxima with ages that match those of the last six heinrich events which we interpret as an indication of the changing strength of the east asian winter monsoon which largely controls the transport and deposition of central asian aeolian dust thus it seems that these heinrich events have left their signature in the chinese loess record this is consistent with simulations of the glacial climate9 which imply that the climates of the north atlantic and china were linked by the effect of westerly winds