environmental inferences and chironomid based temperature reconstructions from fragmentary records of the weichselian early glacial and pleniglacial periods in the niederlausitz area eastern germany abstract we inferred past climate conditions from lacustrine sediments intercalated in weichselian early glacial and early pleniglacial fluvial and aeolian sediments exposed in two opencast lignite mines from the niederlausitz area eastern germany a chronology was established using radiocarbon and luminescence dating methods both lithology and chironomid fauna indicate that the former shallow lakes were situated on a floodplain palaeotemperature estimates calculated from the fossil chironomid assemblages of the early glacial lacustrine deposit indicate mean july air temperatures of ca 15 c which is in line with results derived in earlier studies from the niederlausitz area and from northwestern europe the early pleniglacial lacustrine deposits consist of an organic rich gyttja intercalated with sand and silt lenses the chironomid assemblages show that a shallow meso to eutrophic lake was present at the study site and chironomid inferred palaeotemperature estimates indicate an abrupt decline in july air temperatures from 15 16 c to ca 13 c in combination with other proxies from the same record this suggests a dansgaard oeschger like climate event

holocene climatic and environmental changes inferred from midge records diptera chironomidae chaoboridae ceratopogonidae at lake berkut southern kola peninsula russia a radiocarbon dated sediment sequence from lake berkut in the southern part of the kola peninsula northwest russia was investigated by means of midge analysis in order to reconstruct the holocene climatic and environmental history of the region past mean july air temperatures at the study site and hypolimnetic oxygen contents of the lake water were inferred from chironomid based transfer functions the early holocene c 10 100 8400 cal yr bp is characterized by summer temperatures and hypolimnetic oxygen concentrations broadly similar to present day conditions the midge records give evidence of a lake level fall at c 7000 cal yr bp resulting in weakened thermal stratification of the lake water and improvement of the hypolimnetic oxygen conditions after c 4000 cal yr bp midge assemblages suggest a lake level rise related to increased effective moisture a secondary mid holocene climatic optimum with inferred mean july air temperatures of c 12 1 degrees c was recorded between 6000 and 4400 cal yr bp followed by minimum values c 11 3 degrees c between 3500 and 1500 cal yr bp accompanied by the onset of natural acidification of the lake the late holocene midge assemblages suggest weakly acidic conditions low hypolimnetic oxygen contents and a general warming trend during the last c 1500 years although paludification and natural acidification may have influenced the temperature reconstruction at this stage however the modern chironomid inferred mean july air temperature 12 5 degrees c is consistent with meteorological data from a nearby station in general the midge records reflect relatively warm and moist conditions at lake berkut before c 7000 cal yr bp a relatively warm and dry climate at c 7000 4000 cal yr bp and a shift to cooler and wetter climatic conditions in the region after c 4000 cal yr bp less

late pleistocene climate change and landscape dynamics in the eastern alps the inner alpine unterangerberg record austria drill cores from the inner alpine valley terrace of unterangerberg located in the eastern alps of austria offer first insights into a pleistocene sedimentary record that was not accessible so far the succession comprises diamict gravel sand lignite and thick fine grained sediments additionally cataclastic deposits originating from two paleo landslide events are present multi proxy analyses including sedimentological and palynological investigations as well as radiocarbon and luminescence data record the onset of the last glacial period wurmian at unterangerberg at 120 110 ka this first time period correlated to the mis 5d was characterised by strong fluvial aggradation under cold climatic conditions with only sparse vegetation cover furthermore two large and quasi synchronous landslide events occurred during this time interval no record of the first early wurmian interstadial mis 5c is preserved during the second early wurmian interstadial mis 5a the local vegetation was characterised by a boreal forest dominated by picea with few thermophilous elements the subsequent collapse of the vegetation is recorded by sediments dated to 70 60 ka i e mis 4 with very low pollen concentrations and the potential presence of permafrost climatic conditions improved again between 55 and 45 ka mis 3 and cold adapted trees re appeared during interstadials forming an open forest vegetation mis 3 stadials were shorter and less severe than the mis 4 at unterangerberg and vegetation during these cold phases was mainly composed of shrubs herbs and grasses similar to what is known from today s alpine timberline the unterangerberg record ended at 45 ka and or was truncated by ice during the last glacial maximum

strain path partitioning within thrust sheets microstructural and petrofabric evidence from the moine thrust zone at loch eriboll northwest scotland abstract quartz c axis fabrics and microstructures have been investigated within a suite of quartzites collected from the loch eriboll area of the moine thrust zone and are used to interpret the detailed processes involved in fabric evolution the intensity of quartz c axis fabrics is directly proportional to the calculated strain magnitude a correlation is also established between the pattern of c axis fabrics and the calculated strain symmetry two kinematic domains are recognized within one of the studied thrust sheets which outcrops immediately beneath the moine thrust within the upper and central levels of the thrust sheet coaxial deformation is indicated by conjugate mutually interfering shear bands globular low strain detrital quartz grains whose c axes are aligned sub parallel to the principal finite shortening direction z and quartz c axis fabrics which are symmetric both in terms of skeletal outline and intensity distribution with respect to mylonitic foliation and lineation non coaxial deformation is indicated within the more intensely deformed and recrystallized quartzites located near the base of the thrust sheet by single sets of shear bands and c axis fabrics which are asymmetric with respect to foliation and lineation tectonic models offering possible explanations for the presence of kinematic strain path domains within thrust sheets are considered

late quaternary history of the marmara sea and black sea from high resolution seismic and gravity core studies abstract lithologic and multi proxy paleoenvironmental data from 21 dated cores have been used to define three allostratigraphic units allounits within the late quaternary successions of the marmara sea and black sea allounits are bounded by unconformities and their correlative conformities in both regions allounit a extends from the seafloor downward to a 12 11 ka sequence boundary which is a major shelf crossing unconformity in water depths less than 100 110 m in deep basins of the marmara sea the lower part of allounit a designated subunit a2 is a laminated sapropel m1 on the shelf subunit a2 consists of backstepping delta lobes and early transgressive barrier islands and sand sheets allounit b has only been recovered in marmara sea cores collected at water depths greater than 90 m and represents basinal or prodeltaic deposition during the 23 12 ka late pleistocene lowstand during the last glacial maximum the shelves surrounding the marmara sea were subaerially exposed and deltas of allounit b accumulated along the present day shelf edge following the post glacial rise of global sea level to 75 m at 12 ka the marmara sea quickly became inundated and thereafter rose in synchroneity with the mediterranean by 10 ka the black sea rose to start spilling into the marmara sea leading to establishment of a brackish water lid that has persisted to the modern day the strongest black sea outflow began at 10 ka and persisted to 6 ka promoting the accumulation of sapropel m1 in the deep marmara sea and progradation of an overflow delta just south of the exit from the bosphorus strait allounit c is a laminated sapropel m2 in basinal cores dated at 30 23 ka like m1 it is believed that m2 accumulated during a period of increased brackish water input into the marmara sea mainly from the black sea in the black sea wave erosion kept the shelf stripped of unconsolidated sediments during the falling sea level associated with the last glaciation and subsequent early stages of the post glacial holocene transgression this erosion created a major unconformity shelf edge deltas of allounit b received their sediment during the last lowstand from small rivers that likely coalesced into a single system toward the shelf edge at modern water depths of 100 to 110 m these deltas were active until 11 10 5 ka subsequently sea level in the black sea rose to 40 m by 10 ka and a set of backstepping barrier islands developed on the shelf as part of the associated transgressive systems tract once water level reached 40 m continued sea level rise stalled until 9 ka as the black sea began to spill across the bosphorus strait into the marmara sea

reconstruction of continental margin architecture deformed by the contraction of the lagonegro basin southern apennines italy thrust propagation through previously rifted continental margins may result in fold and thrust belts whose structure is strongly controlled by the inherited basin architecture as it occurs in southern italy the lagonegro units of the southern apennines comprise a deformed pelagic basin succession showing variable stratigraphic characteristics mainly lateral variations in both facies and thickness interpreted to be due to a complex basin topography related to a triassic rifting event in contrast to previous studies cross section balancing and restoration indicate that the lagonegro units exposed in the high agri valley area suffered relatively limited internal shortening 8 km i e 35 early deformation of these rocks later incorporated into a large displacement thrust sheet was dominated by folding around present day roughly north south trending axes the attainment of a regional decollement level was favoured by an early mild inversion of the basin producing a roughly similar structural elevation of both hanging wall and footwall successions to mesozoic faults most of the contractional deformation was accommodated by buckling of the mesozoic syn rift strata between synsedimentary faults which represented major mechanical interfaces early strain localization in the lagonegro basin ahead of the active thrust front was most probably mechanically controlled by a faulted crustal segment which originally lay within the continental margin between two massive carbonate platforms

merging chironomid training sets implications for palaeoclimate reconstructions icelandic and norwegian chironomid calibration or training sets were merged to investigate whether a larger combined training set would be useful to apply to subfossil chironomid data from iceland for periods such as the early holocene the holocene thermal maximum and the little ice age when temperatures can be expected to be outside the current temperature range of the icelandic training set following taxonomic harmonisation the icelandic and norwegian data sets were compared before being merged to form a combined norwegian icelandic training set analyses showed that it was biologically and statistically valid to merge the two data sets the resulting combined inference model for mean july air temperature had improved performance statistics r2jack 0 87 rmsepjack 1 13 when compared to the best performing icelandic model r2jack 0 61 rmsepjack 0 83 due to the longer environmental gradient covered icelandic 6 11 c combined 3 5 16 c and to the increased number of samples icelandic 53 lakes combined 207 lakes and taxa icelandic 47 taxa combined 133 taxa present within the combined training set the inference models were applied to an early holocene chironomid sequence from vatnam ri north iceland and a 450 year recent record from myfluguvatn north west iceland to compare the reconstructions produced the various inference models produced similar trends and patterns of temperature reconstruction but the inference model based on the combined training set produced a larger range of reconstructed temperatures than the icelandic model it was found that different inference models produced more variation in the reconstruction than when different training sets were used a comparison of the myfluguvatn reconstructions with meteorological observations showed that the combined norwegian icelandic inference model produced more reliable results than the icelandic or norwegian inference models alone

calcite twins their geometry appearance and significance as stress strain markers and indicators of tectonic regime a review twin lamellae are a widespread feature in calcites of any type and origin twinning in calcite is an important intracrystalline deformation mechanism with low critical resolved shear stress and virtually no temperature dependence in contrast to most slip systems in rock forming minerals twinning therefore permits intracrystalline deformation at very low temperature and very little confining pressure twinning alone however cannot lead to large strains because only one independent slip system is effectively available twins lead to discontinuous shearing on the grain scale which gives rise to considerable strain incompatibilities at grain boundaries twinning consequently leads to strain hardening detailed observations of the geometry of twin lamellae show that incompatibilities at grain boundaries are eliminated by pressure solution on the grain scale at low temperature and dynamic recovery processes at higher temperatures twins are found in various tectonic environments and record very small strains in rocks deformed under very little cover different twinning strain and twinning stress methods and palaeopiezometers are critically reviewed all methods are limited to strains of less than 15 shortening or extension by twinning twinning nevertheless is an important although not directly measurable contribution to the total strain in highly strained calcite rocks at least up to middle greenschist facies under which conditions it is the most effective contributor to the formation of strong lattice preferred orientations in calcite tectonites the appearance of calcite twin lamellae changes systematically as a function of deformation temperature micro twins and straight narrow 1 5 m but fewer twins are developed above approximately 200 c curved twins twinned twins and completely twinned grains indicate the progressive importance of other slip systems and larger intracrystalline strains are possible at ca 250 c and above ancient straight twin lamellae are modified into irregular geometries by recrystallization and grain boundary migration the appearance of calcite twins is proposed as an approximate but rapid and easy to use geothermometer in low temperature environments

terrace styles and timing of terrace formation in the weser and leine valleys northern germany response of a fluvial system to climate change and glaciation abstract in glaciated continental basins accommodation space is not only controlled by tectonics and sea level but also by the position of ice sheets which may act as a regional base level for fluvial systems although the pleistocene terrace record of major river systems in northwestern europe has been investigated by many authors relatively little attention has been paid to base level changes related to glacier advance retreat cycles and how these regional changes in base level interacted with river catchment processes this study provides a synthesis of the stratigraphic architecture of middle pleistocene to holocene fluvial terraces in the upper weser and middle leine valley in northern germany and links it to glaciation climate and base level change the depositional architecture of the fluvial terrace deposits has been reconstructed from outcrops and high resolution shear wave seismic profiles the chronology is based on luminescence ages 230 th u ages 14 c ages and middle palaeolithic archaeological assemblages the drainage system of the study area developed during the early miocene during the pleistocene up to 170 m of fluvial incision took place a major change in terrace style from strath terraces to cut and fill terraces occurred during the early middle pleistocene before marine isotope stage mis 12 which may correlate with climate deterioration and the onset of glaciation in northern central europe during this time a stable buffer zone was established within which channels avulsed and cut and filled freely without leaving these vertical confines climate was the dominant driver for river incision and aggradation whereas the terrace style was controlled by base level changes during ice sheet growth and decay a major effect of glacio isostatic processes was the post elsterian re direction of the river weser and river leine the middle pleistocene fluvial terraces are vertically stacked indicating a high aggradation to degradation ratio corresponding with a regional base level rise during glacier advance at the beginning of the late pleistocene the terrace style changed from a vertical to a lateral stacking pattern which is attributed to a decrease in accommodation space during glacier retreat the formation of laterally attached terraces persisted into the holocene major incision phases took place during mis 5e 5d 5c and probably early mis 4 early mis 3 and mis 2 lateglacial during mis 5e and the lateglacial the braided river systems changed into meandering rivers indicated by preserved organic rich flood plain and point bar deposits the late pleistocene braided river systems mis 5c to mis 3 are characterized by a high sinuosity which may be a direct effect of an increased downstream gradient after deglaciation when the channel lengthened and the river adjusted to the increased gradient by increasing sinuosity these middle pleniglacial fluvial deposits are unconformably overlain by lateglacial to holocene meandering river deposits which form laterally attached terraces recording millennial scale channel shifts the lack of late pleniglacial deposits might be related to late weichselian forebulge formation

neogene patterns of relative plate motion for africa europe some implications for recent central mediterranean tectonics a detailed relative motion picture for the neogene africa europe plate kinematics is presented the kinematic reconstruction was carried out using the finite difference solution between the rotation parameters determined for anomalies 7 to 2 in the africa north america europe plate motion circuit the analysis shows a motion of africa with respect to europe which is nne directed during late oligocene to burdigalian times becoming nnw trending from the langhian to the early tortonian from upper tortonian times onward the motion changes to a clear north west directed convergence major late neogene tectonic features of the central mediterranean region can to a large extent be explained within the context of the reconstructed major plate motions late tortonian to recent africa europe slip vectors are compatible with a variety of geological phenomenoa such as north west directed subduction beneath calabria south east translation of calabria and extension in the tyrrhenian sea north west trending slip vectors from thrust earthquakes between gibraltar and sicily and dextral strike slip across the north african margin

structure kinematics and metamorphism in the liguride complex southern apennines italy abstract the liguride complex of south italy is the remains of a cretaceous paleogene accretionary wedge which was emplaced onto the african margin during early miocene time transport directions of thrust sheets and nappes in the internal zone are roughly towards the present day northeast transport directions match well with the corresponding slip vectors derived from relative motion of the calabria sardinia corsica block with respect to africa including adria during late eocene to oligocene time deformation of the internal zone included extensive underthrusting followed by underplating of already lithified sediments ophiolitic rocks and continental basement on to the base of an accretionary wedge down to depths in places exceeding 30 km overthickening by massive underplating caused late paleogene gravity driven extension within the accretionary wedge the contact between the lower ophiolitic nappe and the upper ophiolitic nappe is an extensional fault zone of this age transport directions during the gravity driven deformation do not match plate derived slip vectors it is inferred that the gravitational potential of the wedge dominated the kinematics of the late palaeogene extensional deformation

flow in natural shear zones the consequences of spinning flow regimes abstract the ancient flow regime in natural shear zones is often considered to have followed a deformation path comparable to that in theoretical shear zones i e progressive simple shear between rigid wall rocks with a persistent flow plane orientation parallel to the edges of the zone this is often based on the presence of monoclinic fabric elements in the zones which indicate a dominantly non coaxial flow regime though not necessarily persistent simple shear the deformation fabric of a shear zone from the pyrenees illustrates that even at a kinematic vorticity number of w 1 simple shear along the entire deformation path obliqueness of the flow planes with the edges of the zone is possible for some time if incremental stretching axes were rotating with respect to zone edges this implies that ductile deformation must have taken place in the wall rock of the zone such a flow regime may be difficult to recognize with the fabric criteria used at present but leads to an unusual kinematic significance of the shear zone involved in extreme cases the zone may have acted as a passive marker in a ductilely deforming medium it also means that not only w must be known to reconstruct the ancient flow regime in natural shear zones but at least also the time dependence of the orientation of the incremental stretching axes

climatic and environmental reconstructions based on fossil assemblages from middle devensian weichselian deposits of the river thames at south kensington central london uk abstract fossiliferous silts within the late pleistocene kempton park gravel of the river thames valley were exposed in 1980 during foundation works for the ismaili centre in south kensington london the results of a multidisciplinary study of the geomorphology sediments fossil plants vertebrates molluscs ostracods and insects are reported the silts were deposited under two distinct climatic regimes a lower unit accumulated when the climate was arctic and an upper when the temperatures were at least as warm as those of the present day both these units occupy the same channel system and are separated from one another by less than a metre of sediment implying that the climatic change was probably sudden and intense the strongest evidence for this climatic difference comes from a study of the coleoptera which show an almost complete replacement of the arctic element in the fauna by a suite of temperate species palaeotemperature reconstructions using the mutual climatic range method based on the coleopteran assemblages from the lower unit suggest that the mean temperature of the warmest month was 9 2 c and that of the coldest month 22 10 c for the upper unit the mean temperature of the warmest month had risen to about 17 c and that of the coldest month to about 4 c the episode represented by the lower unit with its arctic climate had not previously been recognized in the thames valley the fauna from the upper temperate unit is very similar to that from other sites in the kempton park gravel such as that from isleworth 10 km upriver which like the upper unit at the ismaili centre was characterized by the virtual absence of trees it would appear that in such cases this treelessness does not indicate cold conditions equivalent to those of the modern tundra but may instead result from a combination of ecological and temporal factors the value of multidisciplinary studies in reaching such conclusions is emphasized the temperate episode described here is correlated with the thermal maximum at the early part of the upton warren interstadial complex an earlier suggestion based on amino acid epimerization ratios that the upton warren interstadial correlates with oxygen isotope sub stage 5a is not supported by the data which show no evidence of the forested environments that characterized this period in both britain and the adjacent continent it is thought that the temperate deposits at the ismaili centre belong to the middle pleniglacial rather than the early devensian weichselian and are equivalent to oxygen isotope stage 3

rapid climatic events as recorded in middle weichselian thermokarst lake sediments from a middle weichselian sediment sequence in the opencast brown coal mine of reichwalde eastern germany a 40 cm thick thermokarst gyttja deposit has been sampled the ams 14c dates although at the limit of detection indicate an early middle weichselian age of the gyttja pollen botanical and zoological e g chironomids macroremains have been analyzed botanical and chironomid taxa indicate warm climatic conditions in the bottom part of the sequence for this lower part the botanical data suggest a minimum mean july temperature of 12 14 c following this a cooling is indicated coinciding with an increased clastic deposition in the lake a return to permafrost conditions is reconstructed for the upper part of the sequence the combined evidence strongly suggests a degradation of permafrost due to increased warming in response to a d o event as a forcing factor for the thermokarst lake formation

chironomid inferred air temperatures from lateglacial and holocene sites in north west europe progress and problems abstract non biting midges insecta diptera chironomidae are now widely recognised as powerful biological proxies for inferring past climatic change in this paper the response of chironomid assemblages to lateglacial and holocene climatic change from sites in scotland and norway is discussed analyses have shown that midge assemblages have responded to major and minor climatic fluctuations during the last 15 000 yr such as the aegelsee oscillation gerzensee oscillation and younger dryas in the lateglacial and the thermal optimum little ice age and cooling events at 8 2 and 2 0 cal ka bp in the holocene in an attempt to quantify these and other climatic fluctuations a chironomid mean july air temperature inference model based on a modern calibration set of 109 lakes in norway and svalbard has been developed the 3 component weighted averaging partial least squares inference model performs well with a root mean squared error of prediction of 0 90 c and a maximum bias of 0 59 c both based on leave one out cross validation which is lower than chironomid temperature inference models developed in canada switzerland and finland however while temperature inference models perform well in the lateglacial the more subtle climatic changes of the holocene are more difficult to reconstruct because the likely temperature changes are close to the limits of the prediction errors of the existing models to address this problem future work is required to refine and develop the calibration set by further improving taxonomic resolution by adding more lakes to the calibration set and by investigating the influence of other environmental variables on chironomid distributions and abundances

chironomid inferred late glacial air temperatures at whitrig bog southeast scotland this paper presents the first chironomid inferred mean july air temperature reconstruction for the late glacial in britain the reconstruction suggests that the thermal maximum occurred early in the interstadial with temperatures reaching about 12 degreesc there was then a gradual downward trend to about 11 degreesc punctuated by four distinct cold oscillations of varying intensity at the beginning of the younger dryas mean july temperatures fell to about 7 5 degreesc but gradually increased to about 9 degreesc before a rapid rise at the onset of the holocene the chironomid inferred temperature curve agrees closely both in general trends and in detail with the grip ice core oxygen isotope curve the reconstructed temperatures are 2 4 degreesc lower than coleopteran inferred temperatures but are closer to those inferred from plant macrofossils and glacial equilibrium line altitudes during the younger dryas copyright c 2000 john wiley sons ltd

strain analysis in jurassic argillites of the monte sirino area lagonegro zone southern apennines italy and implications for deformation paths in pelitic rocks analysis of strain in jurassic argillites forming part of the folded and thrusted sedimentary succession of the lagonegro basin southern italian apennines has been carried out using ellipsoid shaped reduction spots as strain markers most of the determined finite strain ellipsoids are of oblate type and show a peculiar distribution of the maximum extension direction x with maxima either subparallel or subperpendicular to the local fold axes using the strain matrix method two different deformation histories have been considered to assist the interpretation of the observed finite strain pattern a first deformation history involved vertical compaction followed by horizontal shortening occurring by a combination of true tectonic strain and volume loss whereby all strain is coaxial and there is no change in the intermediate axis of the strain ellipsoid by this type of deformation sequence which produces a deformation path where total strain moves from the oblate to the prolate strain field and back to the oblate field prolate strain ellipsoids can be generated and may be recorded where tectonic deformation has not been large enough to reverse pretectonic compaction this type of deformation history may be of local importance within the study area i e it may characterize some fold hinge regions and more generally is probably of limited occurrence in deformed pelitic rocks a second deformation sequence considered the superposition of pre tectonic compaction and tectonic strain consisting of initial layer parallel shortening followed by layer parallel shear related to flexural folding also in this instance volume change during tectonic deformation and tectonic plane strain have been assumed for geologically reasonable amounts of volume loss due to compaction and of initial layer parallel shortening this type of deformation history is capable of producing a deformation path entirely lying within the oblate strain field but still characterized by a changeover during deformation of the maximum extension axis x from a position parallel to the fold axis to one perpendicular to it this type of deformation sequence may explain the main strain features observed in the study area where most of the measured finite strain ellipsoids determined from the limb regions of flexural folds display an oblate shape irrespective of the orientation of their maximum extension direction x with respect to the local structural trends more generally this type of deformation history provides a mechanism to account for the predominance of oblate strains in deformed pelitic rocks

the nature of mis 3 stadial interstadial transitions in europe new insights from model data comparisons 15 abrupt warming transitions perturbed glacial climate in greenland during marine isotope stage 3 mis 3 60 27 ka bp one hypothesis states that the 8 16 degrees c warming between greenland stad

lateglacial summer temperatures in the northwest european lowlands a chironomid record from hijkermeer the netherlands lateglacial environments at hijkermeer northwest netherlands were reconstructed by means of chironomid diatom and pollen analyses diatom assemblages indicate that hijkermeer was a shallow oligo to mesotrophic lake during this period pollen assemblages reflect the typical northwest european lateglacial vegetation development and provide an age assessment for the record from the beginning of the older dryas ca 14 000 calibrated 14c yr bp into the early holocene to ca 10 700 calibrated 14c yr bp the chironomid record is characterized by several abrupt shifts between assemblages typically found in mid latitude subalpine to alpine lakes and assemblages typical for lowland environments based on the chironomid record july air temperatures were reconstructed using a chironomid temperature transfer function from central europe mean july air temperatures of ca 14 0 16 0 c are inferred before the older dryas of ca 16 0 16 5 c during most of the allerod of ca 13 5 14 0 c during the younger dryas and of ca 15 5 16 0 c during the early holocene two centennial scale decreases in july air temperature were reconstructed during the lateglacial interstadial which are correlated with greenland interstadial events gi 1d and 1b the results suggest that vegetation changes in the netherlands may have been promoted by the cooler climate during gi 1d immediately preceding the older dryas biozone and gi 1b the hijkermeer chironomid inferred temperature record shows a similar temperature development as the greenland ice core oxygen isotope records for most of the lateglacial and a good agreement with other temperature reconstructions available from the netherlands this suggests that chironomid based temperature reconstruction can be successfully implemented in the northwest european lowlands and that chironomids may provide a useful alternative to oxygen isotopes for correlating european lake sediment records during the lateglacial 2007 elsevier ltd all rights reserved

multiproxy climate reconstructions for the eemian and early weichselian palaeobotanical coleopteran and periglacial data from 106 sites across northwestern europe have been analysed in order to reconstruct palaeoclimatic conditions during the eemian and early weichselian three time slices in the eemian and four in the early weichselian have been considered in the pinus quercetum mixtum corylus phase of the eemian summer temperatures were probably at their highest and the botanic evidence suggests a southeast to northwest gradient for both the warmest and coldest month coleoptera indicate that the summers in southern england were several degrees warmer than those of present day the climate during thecarpinus picea phase was uniform and oceanic without obvious gradients in the final time slice of the eemian the pinus picea abies phase temperatures of the warmest month seem to drop slightly with some indication of a shift towards a more boreal and suboceanic climate the reconstruction of the palaeoclimate in the herning stadial and rederstall stadial is hampered by the limited number of sites but botanical evidence suggests a gradient in temperature of the coldest month from east to west coleoptera from the herning stadial in central england and eastern germany suggest similarly cold and continental climates during the brorup interstadial and the odderade interstadial the botanical evidence suggests that the minimum mean july temperatures rose to 15 16 c but during the coldest month these temperatures show a gradient between 13 c in the east and 5 c in the west 1998 john wiley sons ltd

chironomids as a tool for inferring holocene climate an assessment based on six sites in southern scandinavia abstract chironomid subfossil assemblages from six low alpine and sub alpine holocene stratigraphies are presented and compared they are from five lakes in mid southern and western norway and one in central sweden when comparing the chironomid inferred july air temperatures there are many time segments with a poor among lake fit in inferred temperatures possible environmental variables influencing the fossil chironomid assemblages are discussed using a modern norwegian calibration data set to indicate taxon environment relationships these analyses indicate that local changes in ph water chemistry and productivity at times may have overridden the regional temperature signal in addition other causes of poor among site temperature fit are discussed in particular those related to chronological uncertainties holocene temperature inferences from single cores based on chironomids may not always be able to provide a reliable regional temperature signal but can act as a guide from which hypotheses about past environmental conditions can be tested with the aid of chironomid inferred temperatures from several sites and from other environmental proxies we have obtained a regional picture of holocene summer temperature change by developing a consensus reconstruction based on the overall temperature signal from all six sites this consensus is developed by fitting a smoother through all 330 site specific temperature deviations from the holocene mean the consensus temperature deviations vary from 0 8 c at 8800 cal years bp to 0 8 c at 6500 cal years bp

late glacial climatic oscillations as recorded in swiss lake sediments regional pollen assemblage zones for the late glacial period of the swiss plateau are introduced and defined they include four major zones artemisia juniperus hippophae betula pinus paz with several subzones pollen and oxygen isotope analyses on lacustrine sediments from several lakes in the area reveal four distinct phases of climatic oscillation in the time period of 13 000 9500 yr bp the first oscillation termed the aegelsee fluctuation occurs shortly before 12 000 yr bp and varve counts suggest its duration was ca 100 yr it is characterised by a short decrease in the oxygen isotopes as well as a short increase in nap associated with a depression in birch pollen values the second oscillation which occurs in the 18o record shortly before the deposition of the laacher see tephra ca 11 000 yr bp is termed the gerzensee fluctuation it occurs during a pine dominated phase and its vegetational effects cannot be determined palynologically the most prominent regressive phase is the younger dryas biozone ca 10 700 10 000 yr bp characterised by an increase in heliophilous nap and low 18o values the younger dryas biozone can often be subdivided palynologically into two parts a first part rich in grasses and juniper and a second part with higher filipendula and birch values during the preboreal biozone another distinct oscillation is evidenced only in the oxygen isotope ratios comparison of the swiss oxygen isotope profiles with the greenland dye 3 record suggests that not only the three major shifts in the 18o curves but also the minor ones are closely comparable suggesting some common climatic control

reconstruction of full glacial environments and summer temperatures from lago della costa a refugial site in northern italy abstract vegetation and climate during the last ice age and the last glacial maximum lgm 23 000 19 000 cal bp were considerably different than during the current interglacial holocene cold climatic conditions and growing ice sheets during the last glaciation radically reduced forest extent in europe to a restricted number of so called refugia mostly located in the southern part of the continent on the basis of paleobotanical analyses the euganian hills colli euganei in northeastern italy have previously been proposed as one of the northernmost refugia of temperate trees e g deciduous quercus tilia ulmus fraxinus excelsior acer abies alba fagus sylvatica carpinus and castanea in europe in this study we provide the first quantitative vegetation independent summer air temperature reconstruction for northern italy spanning the time 31 000 17 000 cal yr bp which covers the coldest periods of the last glacial including the lgm and heinrich stadials 1 to 3 chironomids preserved in a lake sediment core from lago della costa 7m a s l a small lake at the south eastern edge of the euganean hills allowed quantitative reconstruction of full and late glacial summer air temperatures using a combined swiss norwegian temperature inference model based on chironomid assemblages from 274 lakes chironomid and pollen evidence from lago della costa derives from finely stratified autochthonous organic gyttja sediments which excludes major sediment mixing or reworking after reconstructing paleo temperatures we address the question whether climate conditions were warm enough to permit the local survival of temperate tree species during the lgm and whether local expansions and pollen inferred contractions of temperate tree taxa coincided with chironomid inferred climatic changes our results suggest that chironomids at lago della costa have responded to major climatic fluctuations such as temperature decreases during the lgm and heinrich stadials the vegetation of the euganean hills shows responses to these climatic oscillations although the effects of temperature changes were probably also strongly influenced by changes in humidity reconstructed july air temperatures at lago della costa never fell below 10 13 c error range of reconstruction 1 5 1 6 c which is considerably above the limit considered necessary for forest growth 8 10 c instead rather mild climatic conditions prevailed 31 000 17 000 cal yr bp with average summer temperatures between 12 and 16 c which most likely allowed survival of temperate tree taxa in the warmest and moistest microhabitats of the euganean hills during the lgm only assuming local survival is it possible to explain the repeated expansions and collapses of temperate trees at lago della costa which faithfully accompanied the climatic oscillations

archean granite greenstone tectonics at kolar south india interplay of diapirism and bulk inhomogeneous contraction during juvenile magmatic accretion 1 the structural study of the kolar greenstone belt and surrounding granite gneiss terrains combined with u pb dating reveals that the middle and lower crustal tectonoplutonic pattern of the eastern dharwar craton developed during a major magmatic accretion event between 2550 and 2530 ma the granite greenstone pattern resulted from the interference of gravity driven sagging of the greenstones i e diapirism e w bulk inhomogeneous shortening combined with horizontal n s stretching and syntectonic juvenile pluton emplacement bulk inhomogeneous contraction is accommodated by the synchronous development of a pervasive n s trending vertical foliation shallow stretching lineation and conjugate strike slip shear zone pattern within and outside the greenstone belt resulting in regional horizontal pure shear deformation the plutons around the greenstone belt record regional contraction by developing one set of strike slip c s fabrics of the shear zone pattern the development of the granite greenstone pattern was coeval and compatible with deformation during juvenile magmatic accretion melting and granulite metamorphism in the lower crust the kolar example points to a specific crustal rheology that allowed sagduction of the greenstones and regional distributed bulk inhomogeneous strain due to mechanical homogeneity and low viscosity provided by large scale melting during the accretion event this example further suggests specific boundary conditions to the craton that allowed e w inhomogeneous shortening to be accommodated by n s stretching and spreading of the crust without significant tectonic thickening such tectonoplutonic pattern is specific to the archean and may develop as a consequence of mantle plume activity in intracontinental settings

10be exposure age chronology of the last glaciation in the krkonose mountains central europe abstract a new chronology of the last glaciation is established for the krkonose giant mountains central europe based on in situ produced 10be in moraine boulders exposure ages and schmidt hammer rebound values obtained for terminal moraines on the northern and southern flank of the mountains suggest that the oldest preserved moraines represent early phases of the last glacial maximum lgm large moraines at the outlet of the snowy cirques niezne kotly and in the middle part of the upa ob i d l trough were deposited around 21 ka while a series of smaller moraines above the lgm deposits represent readvances that occurred no later than 18 1 0 6 ka 15 7 0 5 ka 13 5 0 5 ka and 12 9 0 7 ka an exposure age of 13 8 0 4 ka obtained for protalus ramparts at the foot of the upska jama cirque headwall indicates that glaciers advanced only in north to east facing cirques during the lateglacial the last glacier fluctuation was synchronous with the younger dryas cold event the timing of local glacier advances during the last glacial episode correlates with the late weichselian glacier phases in the alps and in the bavarian bohemian forest

finite strain analysis of a natural ductile shear zone in limestones insights into 3 d coaxial vs non coaxial deformation partitioning abstract in order to obtain new insights into the process of strain localization a ca 50 m thick shear zone has been investigated the shear zone located in the footwall to a major thrust involves limestones and pelites calc mylonites are characterized by a stretching lineation orthogonal to the shear direction and a foliation at an angle of 45 10 to the thrust fault strain analysis and mean foliation analysis have been carried out on 42 samples strain gradients and ellipsoid shape across the shear zone indicate respectively an increase of strain intensity approaching the thrust surface and overall oblate strain apparent flattening increases significantly for intensely deformed rocks theoretical models are proposed to explain the recorded finite strain configuration with a main deformation characterized by simultaneous simple shear and localized pure shear involving lengthening normal to the shear direction a model of asymmetric lateral extrusion is adopted as is consistent with measured horizontal strain gradients this model also takes into account regional geological constraints such as the occurrence of accommodation space along the present day tyrrhenian extensional margin to the sw and of a massive body of platform carbonates forming a rigid buttress to the ne

the carbonate tectonic units of northern calabria italy a record of apulian palaeomargin evolution and miocene convergence continental crust subduction and exhumation of hp lt rocks in northern calabria italy the metasedimentary succession of the lungro verbicaro tectonic unit preserves mineral assemblages suggesting underthrusting to depths in excess of 40 km internal deformation of these rocks occurred continuously during the following decompression index mineral composition associated with progressively younger tectonic fabrics indicates that a substantial part of the structural evolution took place within the blueschist facies p t field despite their tectonic and metamorphic history the rocks of the lungro verbicaro unit preserve significant sedimentary and palaeontological features allowing correlations with successions included in adjacent thrust sheets and the reconstruction of the mesozoic continental margin architecture the subduction exhumation cycle recorded by the lungro verbicaro unit is entirely of miocene age this portion of the apulia continental palaeomargin was involved in convergence related deformation not earlier than the aquitanian the integration of our results with available constraints on the tectonic evolution of the apennine calabrian arc system suggests that subduction and most of the subsequent exhumation of the lungro verbicaro unit occurred up to langhian time at maximum vertical rates in excess of 15 mm a 1 the exhumation process was then completed at much slower rates 1 in late miocene time as indicated by both apatite fission track data and stratigraphic information

strains and folds within thrust sheets an analysis of the heilam sheet northwest scotland abstract the changes of shape and orientation of fossil worm burrows have been used to carry out a detailed strain analysis of the heilam thrust sheet in the moine thrust zone northwest scotland the strains have been factorised into components of layer parallel shear 1 layer normal shear 2 and layer parallel shortening or elongation variations in the 1 shear are largely lithologically controlled some strain is due to flexural processes as the thrusts and overlying beds change dip over thrust ramps or are tightened by later deformation while there may also be a component of drag which increases towards the overlying thrust this predating the shear due to flexure a contoured map of the values suggests that major folds within the thrust sheet developed as a result of stick or drag on the floor thrust prior to ramp climb this led to differential movement in the transport direction causing layer parallel shortening accompanied or followed by buckling of the layers a map showing layer normal shear strains 2 suggests that the heilam sheet forms a major surge zone the central part having moved further wnw than the northern and southern parts this has led to components of lateral shear along parts of the sheet especially in the north producing curvature of the imbricate faults

complex strain patterns developed at the frontal and lateral tips to shear zones and thrust zones abstract many of the complex strain patterns seen in shear zones and thrust zones such as variable fabric orientations refolded folds and fabrics together with folds with hinges almost parallel to the main transport direction can be explained in terms of differential movement within the shear zones these strains are developed at the frontal and lateral tips of the zones as they propagate examples are taken from the moine thrust zone of scotland which show variations in strains particularly at the lateral tips the form of differential movement described here may lead to complex strain paths and non plane strain ellipsoids and the spatial variations in finite strain may be used to delineate zones of extensional and compressional flow and differential movement in the shear zones or thrusts

climatic reconstruction of the weichselian pleniglacial in northwestern and central europe a multiproxy approach is applied to reconstructing accurately the weichselian pleniglacial climate 72 13 ka in northwestern and central europe standardised translations are used to transform proxy data into climate parameter values for six characteristic time windows quantitative reconstructions of the temperature regime are derived from periglacial coleoptera and botanical evidence while aeolian and fluvial evidence provide qualitative information on wind activity and precipitation respectively the early pleniglacial 74 59 ka the cold period between 41 38 ka and the late pleniglacial 27 13 ka are characterised by a strong north to south climatic gradient over northwestern europe during the last glacial maximum discontinuous permafrost was established in northern france whereas the continuous permafrost zone extended from the uk belgium the netherlands germany and poland to the nordic ice sheets prominent wind activity and a relatively low precipitation typify these periods in contrast an indistinct west to east climate gradient was present in the relatively more temperate intervals e g 50 41 ka seasonally frozen ground conditions prevailed in northwestern europe whereas discontinuous permafrost may be suggested for central germany it appears that the climate conditions in northwest and central europe were controlled by three major factors the scandinavian ice sheet the north atlantic surface water circulation and the russian continent 1998 john wiley sons ltd

constraints on geological strain rates arguments from finite strain states of naturally deformed rocks a summary of known finite strain states is presented longitudinal strains 1 e as measured in many rocks often range from 1 to 40 and 1 to 0 025 the time span available to produce such measureable strains in young orogenic zones seems to be less than 10 m y possibly less than 1 m y which constrains conventional strain rates into the range of 10 sup 13 s sup 1 to 10 sup 15 s sup 1 for both pure and simple shear the most efficient way and much less efficient way to accumulate incremental strains respectively the ellipticity of the finite strain ellipse increases in a nonlinear manner finite strain variations in adjacent layers which give rise to features such as cleavage refraction arise with only slight differences in the strain rates within these layers

geological strain analysis a manual for the rf φ technique by richard j lisle pergamon press oxford 1985 viii 99 pp 15 hard cover 8 95 soft cover

late weichselian and holocene record of the paleoenvironmental changes in a small river valley in central poland abstract the developmental history from the oldest dryas to the late holocene of a paleolake and mire located in a river valley in central poland was studied using high resolution records of pollen macrofossils cladocera sedimentology and geochemistry from a 14 c dated sediment core we inferred temperature and water level dynamics using cladocerans and palynological and geochemical methods were employed to investigate natural fluvial activity particularly for these elements that are difficult to find through sedimentological methods our research demonstrates how climate fluctuation in the late glacial and holocene periods influenced the development of a paleolake and mire in a small river valley and shows the importance of long term research to establish hydroclimatic conditions in biogenic sediments we propose that water level fluctuations were important in modifying biotic assemblages the results of our multiproxy analysis clearly suggest that the main driver of changes in aquatic and terrestrial ecosystems as well as in geomorphological processes in the valley was climate reconstructed temperatures generally follow the known trends showing an increase at the beginning of the bolling allerod and holocene and a decrease at the beginning of the oldest and younger dryas similarly periods of water level increase are synchronous with climatic changes however the local environmental forces were a significant factors affecting biotic diversity in the studied time span fish predation macrophyte structure ph and calcium content partly influence the results of the cladoceran based water depth reconstruction in particular interestingly the cladoceran inferred summer temperature reconstruction for pawlowa appear realistic although the temperature trends can be considered reliable our results indicate the important role of local factors which control the species composition of the subfossil assemblages

triassic continental rifting of pangaea direct evidence from the alpujarride carbonates betic cordillera se spain abstract evidence is presented for triassic rift related palaeo structures from the alpujarride complex carbonates of the betic cordillera se spain direct evidence of synsedimentary extensional tectonics is provided by macro to meso scale normal faults overstepped by younger strata most faults define domino like horst and graben structures the faults are associated with an expanded synrift sedimentary prism in which soft sediment deformation gravity flow deposits and unconformities are widely developed syntectonic mafic igneous intrusions also occur the age of this phase of extension is constrained as ladinian carnian c 237 216 ma from a palaeogeographical standpoint the thick triassic carbonates of the betic internal zone together with comparable successions in northern calabria southern apennines occupied a belt with elevated subsidence connecting the neo tethys to the east with the eastern north american intracontinental rift system to the west their carbonate facies intermediate between classical alpine and germanic type triassic facies recorded the main episodes of rifting affecting central pangaea

lower to middle weichselian pedogenesis and palaeoclimate in central europe using combined micromorphology and geochemistry the loess paleosol sequence of alsheim mainz basin germany abstract lower to middle weichselian loess loess derivatives and buried soils of the loess paleosol sequence alsheim central europe were characterised by particle size distribution geochemical and micromorphological data high rates of sedimentation with alternating phases of relocation are the main cause for a much less differentiation into middle and upper weichselian loess paleosol units of the alsheim loess paleosol sequence compared to other loess paleosol sequences e g nussloch near heidelberg whereas the lower weichselian has distinct phases of pedogenesis resulting in ah bw and btw horizons to distinguish between different loess deposits locally and intraregional the degree of fineness is an easily applicable and suitable tool though inappropriate for interregional comparisons the chemical index of alteration cia is low 53 to gallet et al 1998 the highest weathering was detectable for btw horizons with cia values 70 a direct quantitative estimation of mean annual palaeotemperature and mean annual palaeoprecipitation can be provided by calculations based on geochemistry of soil horizons and sediments the present mean annual precipitation map in the mainz basin is 789 mm in contrast palaeoprecipitation data suggest a 150 mm higher amount for the last interglacial btw horizon a much lower amount of around 300 400 mm mapp periods of loess and sandy loess deposition and a mapp of micromorphology shows compacted granular structure and moderately to strongly developed pedality as characteristic properties for aquatic loess whereas channel microstructure with no pedality is typical for loess deposits spongy microstructure suggests a classification of the lower weichselian mosbach humus zones as chernozems the eemian paleosol btw horizon in als iii has only weak clay illuviation characteristic for drier regions in europe palaeoclimate and soil formation of the last glacial interglacial cycle calculated from geochemistry and micromorphological data are in good accordance with other proxy data in central europe this suggests that paleoclimate reconstruction based on palaeopedological analyses could be successfully implemented in europe such data may provide a useful alternative to other proxies for correlating european records

testing the validity of organic and inorganic thermal indicators in different tectonic settings from continental subduction to collision the case history of the calabria lucania border southern apennines italy abstract this paper investigates the applicability of organic and inorganic thermal parameters in a range of thermal conditions from diagenesis to epizone and in hp lt settings within the framework of continental subduction and exhumation in the southern apennines where independent thermobarometric constraints are available two juxtaposed tectonic units the hp lt lungro verbicaro unit in the hanging wall and the non metamorphic pollino ciagola unit in the footwall have been analysed for the lungro verbicaro unit clay mineral thermal parameters and vitrinite reflectance underestimate metamorphic conditions constrained by petrology suggesting that in relatively hp units these indicators are retarded9 and strongly depend on p t evolution through time on the other hand the k white mica b cell dimension provides a robust estimate of peak pressure fluid inclusion textures indicate a fast isothermal decompression during exhumation two phase inclusions from early stage syntectonic veins were trapped after isothermal exhumation at a pressure of 0 3 gpa for the pollino ciagola unit the correlation of analysed parameters effectively unravels the thermal evolution with maximum palaeotemperatures of c 150 c apatite fission tracks provide details of the final stages of exhumation indicating that both units were coherently exhumed in the late miocene following the tectonic emplacement of the lungro verbicaro unit on top of the pollino ciagola unit supplementary material x ray diffraction data whole rock composition quantitative analysis of the b cell dimension are available at http www geolsoc org uk sup18416

a chironomid based holocene summer air temperature reconstruction from the swiss alps we developed a quantitative chironomid july air temperature inference model based on surface sediments from 81 swiss lakes and applied it to the holocene subfossil chironomid record of hinterburgsee a small subalpine lake in the northern swiss alps present day mean july air temperature of 11 3 c after smoothing to reduce the high between sample variability of inferred temperatures the reconstruction indicates july air temperatures of 10 4 10 9 c at the end of the younger dryas of 11 9 12 8 c during the early and mid holocene 11500 4000 cal bp and slightly lower temperatures of 11 5 12 0 c during the late holocene 3500 1000 cal bp a warming trend inferred for the past millennium is most likely an artifact of human impact on hinterburgsee s chironomid fauna rather than a genuine temperature signal the most prominent climatological events during the holocene were two periods of lower temperatures at c 10700 10500 cal bp and 8200 7700 cal bp and an abrupt shift to a cooler late holocene cl

some observations on tunnelling of trapped electrons in feldspars and their implications for optical dating abstract anomalous fading in feldspars is now understood to be caused by the tunnelling of electrons from one defect site to another here we present some experimental observations concerning the phenomenon the fading rates of a variety of feldspar crystals and k feldspar separates from sediments are reported it is found that 1 the fading rates of 77 k feldspar extracts from sediments range from 1 to 10 decade with an average value of about 5 decade 2 the fading rates of k feldspars extracted from sediments derived largely from volcanic bedrock are not higher than those from non volcanic bedrock as is widely thought 3 the fading rates of 31 individual feldspars range from 1 to 35 decade 4 in plagioclase feldspars the fading rate increases with increasing ca and or fe content 5 the fading rate increases with laboratory radiation dose at large doses 6 for samples for which the time elapsed since burial is long enough for their luminescence to be in saturation the fading rate is correlated with the ratio of the field saturation intensity to the laboratory saturation intensity extrapolation to zero fading rate shows that trap emptying as a result of thermal eviction is not significant and that the mean thermal lifetime in temperate environments of electrons in traps relevant to dating is 4 ma and 7 different aliquots of a sample can have fading rates that differ by a factor as large as two even if the aliquots contain several thousands of grains thus it is necessary to ensure when correcting ages for anomalous fading that the fading rate used is that applicable to the aliquots on which the equivalent dose is measured

sensitivity of weichselian fluvial systems to climate change nochten mine eastern germany abstract this paper aims to contribute to the understanding of fluvial system response to climate change during the last glacial interglacial cycle fluvial and aeolian successions have been studied in the opencast brown coal mine nochten in eastern germany an absolute chronology was established by luminescence and 14 c dating enabling to demonstrate the relations between depositional units and changes in sedimentary environment over time with regional climatic and vegetational changes it is concluded that the major climatic periods coinciding with the oxygen isotope stages are generally reflected in the fluvial sequence by distinct fluvial environments major climatic changes oxygen isotope stage boundaries have been preserved in the fluvial record as erosional bounding surfaces and by changes in fluvial style rapid climate changes like the middle pleniglacial dansgaard oeschger cycles are in general not reflected in the fluvial succession these cycles were too short or with too low amplitude to cause a strong vegetational response and related changes in water and sediment supply it is emphasized that also the preservation potential of short lived climatic warming events in high energy fluvial systems is low warming events may however have been preserved in lacustrine successions in former thermokarst lakes a strong cooling event at ca 40 ka leading to continuous permafrost conditions and changes in the water and sediment budget was reflected in the fluvial archive by a change from sandy anabranching to braided river conditions

reconstruction of deformation and flow parameters from deformed vein sets abstract in any homogeneously deformed material sets of material lines with a similar stretch history occupy sectors with a scale and orientation that depend on finite strain area change rate and vorticity of the parent flow if the size and shape of these material line sectors are known they can be used to determine the sense of shear and to calculate deformation and flow parameters even if actual stretches along material lines are unknown in rocks which have undergone near homogeneous deformation on a large scale the orientation of sets of boudinaged folded and folded boudinaged or boudinaged folded veins can be used for such calculations a general theoretical background to the problem is presented and a mohr circle construction to carry out the deformation and flow analysis is introduced among other statements the theory predicts that shortened or folded boudins must develop in non coaxial monophase deformation with considerable area change in the plane of observation or in polyphase deformation

ductile strain partitioning in micritic limestones calabria italy the roles and mechanisms of intracrystalline and intercrystalline deformation the apennine pollino ciagola limestone unit in northern calabria is characterized by subgreenschist heterogeneous ductile strain localized along narrow deformation zones at several stratigraphic levels paleogene conglomerates and jurassic calcareous breccias and ooidal packstones have been analyzed with the aim of characterizing the deformation of limestone as a function of the strain recorded by sedimentary markers reference sections parallel to principal finite strain planes were prepared at each locality for the study of specific parameters image analysis of polished sections by scanning electron microscopy sem was used to obtain the finite strain of calcite grains by rf harmonic mean and normalized fry methods for the range of grain sizes analyzed 1 10 m the ellipticity of calcite grains varies as a function of grain size according to a power law relationship from which the size of isometric grains is empirically predicted the finite strain ellipticity determined from single calcite

vegetation and climate during the weichselian early glacial and pleniglacial in the niederlausitz eastern germany macrofossil and pollen evidence cryoturbated organic beds and channel fills intercalated with sandy and gravelly fluvial units have been studied in an opencast brown coal mine near nochten niederlausitz eastern germany the fluvial aeolian sequence covers parts of the early pleni and late glacial the detailed chronology is based on 11 radiocarbon and 12 osl dates covering the period between ca 100 kyr and 11 kyr bp basal peat deposits are correlated with an early weichselian interstadial during this period boreal forests were present and minimum mean summer temperatures were 13 c early pleniglacial deposits are absent the middle and late pleniglacial environments were treeless and different types of tundra vegetation can be recognised minimum mean summer temperatures varied between 10 and 15 c vegetation and climate is reconstructed in detail for the periods around 34 38 kyr bp and 24 25 kyr bp around 34 38 ka a mixture between a low shrub tundra and a cottongrass tussock subshrub tundra was present the botanical and sedimentological data suggest that from the middle to the late pleniglacial the climate became more continental aridity and wind strength increased and the role of a protecting winter snow cover decreased a sedge grass moss tundra dominated around 24 and 25 kyr bp copyright 2001 john wiley sons ltd

holocene coastal change in the ancient harbor of yenikapi istanbul and its impact on cultural history an extensive rescue excavation has been conducted in the ancient harbor of istanbul yenikapi by the sea of marmara revealing a depositional sequence displaying clear evidence of transgression and coastal progradation during the holocene the basal layer of this sequence lies at 6 m below the present sea level and contains remains of a neolithic settlement known to have been present in the area indicating that the sea level at 8 9 cal ka bp was lower than 6 m below present sea level advanced to its maximum at 6 8 7 cal ka bp drowning lykos stream and forming an inlet at its mouth after 3 cal ka bp coastal progradation became evident subsequent construction of the byzantine harbor theodosius 4th century ad created a restricted small basin and accumulation of fine grained sediments the sedimentation rate was increased due to coastal progradation and anthropogenic factors during the deposition of coarse grained sediments at the upper parts of the sequence 7th 9th centuries ad the harbor was probably abandoned after the 11th century ad by filling up with lykos stream detritus and continued seaward migration of the coastline

studies of strain and rheology of conglomerates abstract conglomerates can show significant strain variations among their component rock types previous studies have exploited this feature as a method of quantifying the effective viscosity ratios among different rock types using inclusion matrix models that we review here we further investigate the rheology of conglomerates via models of multiphase mixtures of spherical clasts with varying phase fractions using idealised models with two to four phases we can quantify the influence of phase viscosities and volume fractions on the bulk viscosity and reveal how this controls the strain partitioning among the different phases we consider practical methods of analysing conglomerates and choose r f analysis for measuring clast strain and fry analysis for whole rock strain the methods are illustrated through case studies of two very different conglomerates the port askaig tillite scotland and cesson conglomerate brittany we define the important rock phases in each and assess their strain variations although providing strain measurements of regional interest our main purpose is to quantify the viscosity ratios among the component rocks we find that among the most common rock types semipelite quartzite psammite volcanics granite the viscosity ratios span about one order of magnitude agreeing with previous studies these small numerical values for viscosity ratios among many rock types in many conglomerates lead us to conclude that these rocks each deformed at approximately constant viscosity i e as linearly viscous rather than according to a power law

kinematic reworking and exhumation within the convergent alpine orogen abstract kinematic data from the internal zones of the western alps indicate both top to se and top to nw shearing during synkinematic greenschist facies recrystallisation rb sr data from white micas from different kinematic domains record a range of ages that does not represent closure through a single thermal event but reflects the variable timing of synkinematic mica recrystallisation at temperatures between 300 and 450 c the data indicate an initial phase of accretion and foreland directed thrusting at ca 60 ma followed by almost complete reworking of thrust related deformation by se directed shearing this deformation is localised within oceanic units of the combin zone and the base of the overlying austroalpine basement and forms a regional scale shear zone that can be traced for almost 50 km perpendicular to strike the timing of deformation in this shear zone spans 9 ma from 45 to 36 ma the se directed shear leads to local structures that cut upwards in the transport direction with respect to tectonic stratigraphy and such structures have been interpreted in the past as backthrusts in response to ongoing alpine convergence however on a regional scale the top to se deformation is related to crustal extension not shortening and is coincident with exhumation of eclogites in its footwall during this extension phase deformation within the shear zone migrated both spatially and temporally giving rise to domains of older shear zone fabrics intercalated with zones of localised reworking top nw kinematics preserved within the combin zone show a range of ages the oldest 48 ma may reflect the final stages of emplacement of austroalpine units above piemonte oceanic rocks prior to the onset of extension however much of the top to nw deformation took place over the period of extension and may reflect either continuing or episodic convergence or tectonic thinning of the shear zone 40ar 39ar data from the region are complicated due to the widespread occurrence of excess 40ar in eclogite facies micas and partial ar loss during alpine heating reliable ages from both eclogite and greenschist facies micas indicate cooling ages in different tectonic units of between 32 and 40 ma these ages are slightly younger than rb sr deformation ages and suggest that cooling below ca 350 c occurred after juxtaposition of the units by se directed extensional deformation our data indicate a complex kinematic history involving both crustal shortening and extension within the internal zones of the alpine orogen to constrain the palaeogeographic and geodynamic evolution of the alps requires that these data be integrated with data from the more external zones of the orogen complexity such as that described is unlikely to be restricted to the western alps and spatially and temporally variable kinematic data are probably the norm in convergent orogens recognising such features is fundamental to the correct tectonic interpretation of both modern and ancient orogens

experimental observations on the effect of interface slip on rotation and stabilisation of rigid particles in simple shear and a comparison with natural mylonites for axial ratios r not vert similar3 porphyroclasts from three mylonites all show a very strong spo with the long axis of the best fit ellipse at an antithetic angle of 5 10 to the shear direction this is more consistent with a stable end orientation than with the transient fabrics predicted by theory for elliptical rigid particles in simple shear the cause of this divergence is investigated in a series of high simple shear strain 15 analogue experiments performed in a ring shear machine couette flow using a linear viscous matrix pdms the rotational behaviour of elongate r not vert similar5 rigid particles with elliptical and rhomboidal shapes comparable with the natural examples is modelled for both coherent and slipping particle matrix interfaces interface slip causes a dramatic reduction in the rotation rate of the elliptical particle compared with theory when the long axis is close to the shear direction but not stabilisation interface slip does result in stabilisation of the rhomboidal particle with the long diagonal oriented at a small antithetic angle to the shear direction for monoclinic particles mirror image shapes referred to here as types 1 and 2 show different rotational behaviour for the type 1 particle with a shape comparable to porphyroclast systems and mica fish the long side rotates asymptotically into parallelism with the shear direction natural examples of type 1 particles such as hornblende and olivine porphyroclasts measured from the finero mylonites southern alps show a very strong preferred orientation for r not vert similar3 with the long side parallel or at a small 5 antithetic angle to the mylonitic foliation for type 2 particles the short side stabilises close to the shear direction or at a small synthetic angle as also observed for sillimanite porphyroclasts from the mont mary mylonites western alps in this natural case stabilisation of the short sides is against an extensional crenulation cleavage rather than the mylonitic foliation the analogue experiments establish that interface slip is one mechanism for stabilisation of elongate rhomboidal particles in natural examples decoupling from the matrix may be affected by extensional crenulation cleavage or c planes in s c fabrics

estimation of volume changes by comparative chemical analyses in heterogeneously deformed rocks folds with mass transfer abstract this paper presents a method for calculating the volume change between the various sectors of the same heterogeneously deformed layer fold shear zone by comparing the chemical composition of deformed sectors with that of a reference sector the principle consists of considering some minerals as being insoluble illite chlorite and passively concentrated in deformed zones because of the loss of more soluble minerals quartz calcite dolomite by pressure solution simple observations can be used to test the validity of the assumptions required to calculate volume change in the analysis of a slaty matrix around a ptygmatic fold a map of values is drawn and these values are shown to be compatible with the general strain pattern for several limb hinge pairs of straight limbed folds the relations between volume change elongation parallel to limb layering l l o and the angle between limb and hinge are determined the influence of various parameters such as temperature pressure initial composition and structure of the rock on these relations is also pointed out

the strain and textural history of thin skinned tectonic zones examples from the assynt region of the moine thrust zone nw scotland abstract the moine thrust zone at assynt is a classical example of a foreland propagating thin skinned thrust zone ideal for an examination of thrust related folds deformation textures and strains and complex incremental strain history divergent transport directions oblique trending folds duplex zones and extensional strains normal to the main transport direction may all be explained in terms of thrust propagation leading to the development of oblique to lateral ramps the majority of thrusts cut up section from basement to cover in the transport direction but there is also localised extensional flow and thinning of the thrust sheets in northern assynt the thrust zone involves a wide vertical zone of sinistral shear within which forethrusts backthrusts and associated folds and cleavages are oblique to the general transport direction it is suggested that north of this shear the thrusts moved further probably under a thicker cover while to the south movement was more intermittent probably under a thinner cover this variation is probably due to a change in thrust geometry in the moines east of the moine thrust zone causing a variation in gravitational potential along the length of the moine thrust

a compilation of western european terrestrial records 60 8 ka bp towards an understanding of latitudinal climatic gradients terrestrial records of past climatic conditions such as lake sediments and speleothems provide data of great importance for understanding environmental changes however unlike marine and ice core records terrestrial palaeodata are often not available in databases or in a format that is easily accessible to the non specialist as a consequence many excellent terrestrial records are unknown to the broader palaeoclimate community and are not included in compilations comparisons or modelling exercises here we present a compilation of western european terrestrial palaeo records covering entirely or partially the 60 8 ka intimate time period the compilation contains 56 natural archives including lake records speleothems ice cores and terrestrial proxies in marine records the compilation is limited to include records of high temporal resolution and or records that provide climate proxies or quantitative reconstructions of environmental parameters such as temperature or precipitation and that are of relevance and interest to a broader community we briefly review the different types of terrestrial archives their respective proxies their interpretation and their application for palaeoclimatic reconstructions we also discuss the importance of independent chronologies and the issue of record synchronization the aim of this exercise is to provide the wider palaeo community with a consistent compilation of high quality terrestrial records to facilitate model data comparisons and to identify key areas of interest for future investigations we use the compilation to investigate western european latitudinal climate gradients during the deglacial period and despite of poorly constrained chronologies for the older records we summarize the main results obtained from nw and sw european terrestrial records before the lgm

fry and rf ϕ strain methods constraints and fold transection mechanisms in the nw iberian variscides abstract apulia is a small portuguese sector in nw of central iberian zone that have been deformed in a non coaxial sinistral transpressive regime during the first and main variscan tectonic event d1 this deformation give rise to a major nw se anticline where the s1 n s cleavage transect the inverted short ne limb two and three dimensional strains analysis have been done in the low metamorphic grade ordovician quartzites of this limb using fry and rf methods the data show that most deformation was due to intergranular deformation mechanisms the intragranular deformation leading to the distortion of strain markers and to cleavage was very incipient and a latter event in the d1 phase the apparent plane strain ellipsoids if no volume change is assumed related to the intragranular mechanisms contrast with the more prolate strain ellipsoids related to the bulk deformation of apulia quartzites this constrictional bulk strain fabrics are characteristic of the sinistral transpressive regimes dominant in the northern sectors of the central iberian zone

sense of overthrust shear in the alpine nappes of calabria southern italy abstract southern italy consists tectonically of ophiolite and basement nappes thrust over the apenninic sedimentary nappes whilst all more recent authors agree that the sediments of the apenninic nappes were deposited on apulian basement i e on african continental crust and that the ophiolites were associated with the oceanic basement of the mesozoic tethys the provenance of the basement nappes is still debated new data based on microstructural criteria have shown that the main shear sense of the ophiolite nappes and of the overlying basement nappes in northern calabria is from west to east in today s co ordinate system the basement nappes might not therefore be of austroalpine african provenance but could be of european origin

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

fluvial response to weichselian climate changes in the niederlausitz germany the last glacial shows large variations in climate which are reflected in the fluvial record in the niederlausitz eastern germany the entire sequence resembles the fluvial development in other river basins in northwestern europe which show contemporaneous changes in depositional style at the onset of a climatic change during the middle and the late pleniglacial permafrost conditions resulted in an episodic river discharge the presence or absence of vegetation in combination with such ephemeral stream conditions determined the type of river during each period a relatively well developed vegetation cover on the flood plains during the middle pleniglacial resulted in a low sediment yield in combination with the intermittent discharge this caused the development of an ephemeral anastomosing river system a river with stable channels and extensive sandy overbank areas the decline in vegetation cover at ca 28 ka bp caused an increase in sediment yield and peak discharges which resulted in the development of a sandy braided river in adjustment to these new conditions following the coldest period at around 20 ka precipitation was so low that fluvial activity was limited and aeolian deposition took place in the valley 1997 by john wiley sons ltd

analysis of deformation paths in shear zones the geometry of ductile shear zones can be used to solve problems of regional tectonics if the deformation path of material in the zones is sufficiently understood flow in many shear zones may have deviated from simple shear and consequently data on the final deformation state such as finite strain and volume change are insufficient for reconstruction of the deformation path even if flow parameters were constant during progressive deformation additional information on the flow vorticity number is also needed and can be obtained from fabric elements such as sets of folded boudinaged veins rotated porphyroblasts and blocked rigid objects mohr circle constructions are presented as a tool to calculate deformation parameters from fabric data to represent the deformation path graphically and to reconstruct flow parameters from the shape of this path if the vorticity number or the volume change rate changed during progressive deformation the deformation path can be partly reconstructed using sets of fabric elements which register mean and final values of these parameters

midges and palaeotemperature reconstruction the north american experience abstract the development of midge based palaeoclimatology in north america is reviewed with a focus on lateglacial and holocene climatic change although relatively few sites have been studied midge inferred palaeotemperatures reveal detailed records of lateglacial climate oscillations and more subtle holocene temperature changes holocene climate changes are often at or near the detection limit using current palaeotemperature inference models interference from other environmental variables including water depth and oxygen concentration changes are discussed as well as the challenges inherent to developing better models the isotopic signature of chitin preserved in midge head capsules has opened new avenues for midge palaeotemperature inference through coordinated research efforts national and international collaborations will provide opportunities to reconstruct holocene palaeoclimate at continental and hemispheric scales

changes in the thermal climate in northwestern europe during marine oxygen isotope stage 3 estimated from fossil insect assemblages abstract more than 30 fossil coleopteran beetle assemblages have been recorded from oxygen isotope stage 3 in northern europe comprising several hundred identified species using the mutual climatic range method for quantifying palaeotemperatures these assemblages show that the climates of the times can be divided into two distinct interstadial types one a short phase of temperate oceanic climate occurred between 43 000 and 42 000 14c yr b p when conditions were not much different from those of the present day in spite of the temperate climate trees did not colonize northwestern europe at this time two both before and after this temperate interlude there were phases of cold continental climate during which summers were too cold for trees to grow and winters were of siberian intensity it is possible that periods of even colder conditions intervened from time to time between the interstadial but because of the intensity of the cold biological systems were so inhibited that no fossil evidence for them can be found in northern europe evidence for them must be sought in the fossil records from the warmer parts of southern europe or in the physical evidence in the greenland ice cores

late holocene ecological shifts and chironomid inferred summer temperature changes reconstructed from lake uddelermeer the netherlands abstract this paper presents a late holocene chironomid inferred record of july air temperature from a core obtained from lake uddelermeer in the netherlands the core interval which dates from 2500 to 400 cal yr bp was analysed at multi decadal resolution for organic content pollen spores and npps non pollen palynomorphs and chironomid head capsules these proxies indicate that from 2500 to 1140 cal yr bp the lake was mesotrophic and sustained a littorellion community while the chironomid assemblage was dominated by littoral species associated with macrophytes at 1140 cal yr bp a shift in the lake ecology occurred from low nutrient to high nutrient conditions dominated by algae this shift might be linked to a concurrent increase in human impact and is reflected in the chironomid assemblage by increases in eurytopic taxa which are resistant to disturbances shifts in the chironomid record between 2500 and 1140 cal yr bp do not coincide with changes in lake ecology and are presumably driven by climate change using a norwegian swiss calibration dataset as a modern analogue we produced a chironomid inferred temperature c it reconstruction this reconstruction compares well to other regional temperature reconstructions in timing and duration showing a roman warm period between 2240 and 1760 cal yr bp a dark age cold period starting at 1760 cal yr bp and the medieval climate anomaly beginning at 1280 cal yr bp the c it record indicates a temperature drop of 1 5 c from the roman warm period to the dark age cold period findings improve knowledge of the first millennium ad in nw europe which was characterised by changes in landscape vegetation society and climate

characterising and dating weichselian organogenic sediments a case study from the lusatian ice marginal valley scheibe opencast mine eastern germany abstract dates determined with three absolute dating methods 14c luminescence and 230th u supported the findings of the paleobotanical investigations of the weichselian upper fluvial sequence of the scheibe opencast mine in the niederlausitz lower lusatia eastern germany they allowed to identify three units of organogenic sediments organogenic complexes oc developed as peaty and or humic silts samples from the uppermost oc i unit displayed 14c age ranges from 32 to 28 and 26 to 24 ka respectively for the latest phase an open landscape was identified although high arboreal values point to locally extended sparse forests the lithologically and paleobotanically heterogeneous oc ii unit 37 ka represents at least two periods during which organic matter accumulated in an open landscape the uppermost subunit represents an unforested interstadial of the middle pleniglacial the lowermost oc iii unit has an age of about 56 ka or higher according to the 230th u or tl dates respectively it represents a forested interstadial assigned to the early weichselian

climatic control on quaternary fluvial sedimentology of a fenland basin river england understanding and interpreting climate response from ancient fluvial deposits requires a combined approach of detailed sedimentological description and interpretation local climate proxies and the accurate comparison of these sequences with further independent climate records application of these multiple lines of evidence is particularly effective in the quaternary period where higher resolution and more detailed palaeoenvironmental reconstruction are possible this paper presents results from a devensian weichselian age sequence in northern fenland england that integrates these approaches detailed sedimentological description has identified three fluvial facies associations overlain by a period of ice wedge cast formation fossil plant and coleopteran material within these sediments have been studied to provide palaeoenvironmental reconstructions for the local landscape including quantitative temperature estimates using the mutual climatic range method on fossil coleoptera in addition joint application of radiocarbon and optically stimulated luminescence osl dating allows this sequence to be compared with the stacked marine isotope record although dates do not agree well at the limit of the radiocarbon technique sedimentological interpretations palaeoenvironments and global ice volume variations a proxy for climatic severity are all in agreement and show clearly how the river nene responded to subtle changes in climate and vegetation cover during the devensian weichselian stage the level of detail possible in this reconstruction shows the importance of this approach in understanding fluvial response to past climate changes

strain partitioning in the helvetic thrust belt of eastern switzerland from the leading edge to the internal zone abstract the strain and strain partitioning in the helvetic thrust belt are analysed in order to determine their variation across the belt from the external thin skinned portion to the internal thick skinned portion and in order to begin the detailed mechanical analysis of the entire fold and thrust belt coarse grained limestones of jurassic and cretaceous age were chosen for analysis because they can be traced from the external to the internal zones the strain within a bed is partitioned into three components transgranular pressure solution microfaults veins twinning granular and intragranular exclusive of twinning crystal plasticity associated with recrystallization transgranular strain was very important in the early history of the helvetic nappes giving way to twinning at a later stage under tectonic burial twinning strain was early in the infrahelvetic complex giving way to intracrystalline deformation at the later stage of burial the transition from transgranular to intragranular dominated strain occurred at a vitrinite reflectance value of 3 5 significantly below the greenschist grade of metamorphism in a large scale fold at the leading edge of the helvetic nappes transgranular strains were associated with the buckling stage of the fold and twinning occurred during fold tightening in more internal parts of the helvetic nappes twinning strains are also late with regard to transgranular strains but here their pattern corresponds to the regional finite strain pattern in the internal zone the infrahelvetic complex twinning seems to have been an early event and records an initial layer parallel shortening followed by regional internal deformation with intragranular strains