the stabilization of self organised leucogranite networks implications for melt segregation and far field melt transfer in the continental crust abstract net structured leucocratic vein systems are ubiquitous in high grade and migmatite terrains and are interpreted to represent interconnected former magma bearing structures that accommodated the migration of granitic magmas out of their anatectic source regions net structured leucogranite vein systems in high grade gneisses from the damara belt in namibia describe a size based hierarchy and spatial distribution that indicates self organisation of the magma transfer system the internal geometry and connectivity of the net structured leucogranites are controlled by variations in melt pressure whereas regional strains control the orientation of the leucogranites foliation parallel stromatic and shear band hosted granite veins accommodate transport at relatively low melt volumes and account for the metre scale segregation of melt close to the anatectic source during times of higher melt supply the formation of extensional fractures that cross cut stromatic and shear band hosted melt sheets at high angles is promoted extensional fracturing and associated dilatancy create gradients in magmastatic head that cause melt to be drained from pervasive stromatic and shear band hosted vein networks into spaced dilatant fractures this has the potential to initiate buoyancy driven far field melt transfer along suitably orientated extensional fractures as vertical dykes or self propagating hydrofractures our results suggest that melt transfer systems are able to adjust to variations in melt supply by forming conduits that accommodate varying melt volumes and will tend to develop towards a state of self organisation

site specific variability of loess and palaeosols ruma vojvodina northern serbia abstract the study of temporal variations in soil intensity has mostly been limited to specific sites however it is important for correctly interpreting the stratigraphy and palaeoclimatic significance of loess and palaeosols series to understand the reasons for the spatial variability more specifically pedogenetic and sedimentological properties should be evaluated separately this is particularly well illustrated at the ruma site serbia in this paper we focus on macroscopic soil characteristics and sediment grain size properties the type succession shows three interglacial pedocomplexes v s1 v s2 and v s3 separated by loess layers that include at least one interstadial pedocomplex in the uppermost loess layer all sediments show a bipartite grain size distribution a coarser grained silt dominated one and a fine grained one

constriction in a transpressive regime an example in the iberian branch of the ibero armorican arc abstract detailed strain analyses in the armorican quartzites have been performed in various places within the centro iberian zone of western europe the observed strain pattern shows that in the inner ibero armorican arc as well as near the hinge zone sinistral transpression produces constrictive ellipsoids in the outer arc away from the hinge zone the deformation regime produces plane strain to oblate strain ellipsoids some of these data clearly contradict existent kinematical models which associate constriction with transtension and consider transpression zones to generate oblate strain ellipsoids however newly developed models show that it is possible to obtain a wide range of finite strain ellipsoids in transpression zones if one takes account of lateral escape axial depression and volume change the geodynamic implications of the strain analyses suggest generation of constriction in a transpressive regime caused by lateral expulsion in front of the cantabrian indenter that produced the ibero armorican arc this mechanism was responsible for the variscan wrench component in western europe which was mainly sinistral in iberia and dextral in britanny in iberia the displacement by lateral escape was easily accommodated by subduction of the south portuguese terrane under the ossa morena zone of the iberian terrane

comment on the nature and origin of ureilites by j l berkley et al abstract the record of primordial noble gases in ureilites imposes serious constraints on models of ureilite petrogenesis it is argued that the inhomogeneous distribution between different mineral phases and the low 40 ar 36 ar ratio in particular can only be satisfied with difficulties in the model proposed by berkley et al

contrasting textures in metamorphic and anatectic migmatites an example from the scottish caledonides a method for the quantitative analysis of the spatial relations of minerals is described dispersed distributions are formed by annealing and destroyed in post tectonic migmatization aggregate distributions characterize solid state differentiation whereas leucosomes formed in systems of high fluid rock ratio in the examples studied anatectic melts show random distributions quantitative textural analysis can be used to indicate whether migmatization was post tectonic or earlier though caution is necessary if post migmatite cooling is slow or if there is some minor deformation more importantly it can be used to discriminate melt present from melt absent leucosomes this is exemplified by a suite of metamorphic and anatectic migmatites from the scottish caledonides the textural evolution of anatexites with increasing melt percentage is traced initial feldspar porphyroblastesis occurs by ostwald ripening via grain boundary melts subsequently ophthalmites develop with fabrics and chemistry inherited from the palaeosome at greater than 30 melt these inherited fabrics are wholly destroyed deformation prompts segregation into melanosome and leucosome resultant leucosomes contain no inherited crystals the scale of anatectic systems is fixed at the point at which segregation begins ophthalmites provide evidence for melt and crystal transfer beyond original palaeosome boundaries in contrast metamorphic migmatites are necessarily small scale systems because of diffusive constraints and melanosomes are invariably produced

a biotic record of paleoenvironmental changes during the last interglacial glacial cycle in a sub carpathian river valley a case study of the radymno loess section se poland abstract the studied radymno loess section is located in the large fore carpathian san river valley sandomierz basin se poland and shows the sequence building the pleistocene cover of middle terrace of the san river such sequence is quite rare in loess deposits because it combines different depositional environments subaqueous the late eemian early vistulian alluvial swamp facies of loess with inserts of gyttja type and subaerial the plenivistulian aeolian loess the main goal of the study was to reconstruct the late pleistocene paleoenvironmental changes recorded in this section for this purpose pollen and fossil ostracoda analyses were conducted these data were supplemented with sedimentological and pedo lithological analyses additionally the results of earlier investigations published so far have been used lithological and malacological analyses as well as luminescence irsl and tl dating based on the analysis of many indicators the paleoenvironmental changes have been correlated with those recorded in pollen diagrams obtained from other regions this correlation indicates that in the radymno section there is evidence of the vegetation succession typical of the eemian interglacial with climatic optimum and of the short term oscillations in the early vistulian and then in the lower pleniglacial of vistulian the analysis of fossil ostracoda which were found in some parts of the profile provided information about short term paleohydrological changes and especially about the functioning of surface water bodies in changing periglacial conditions of the bottom of the san river valley in mis 5d mis 2 high humidity in the environment was caused mainly by floods and high groundwater level which indirectly conditioned the formation of water bodies in the valley bottom correlation with palynological data indicated that these water bodies existed also under dry climate conditions this proves that the local conditions of the studied area strongly modified the environmental changes dependent on paleoclimate

constrictive deformation in transpressional regime field evidence from the cauvery shear zone southern granulite terrain india abstract the paper describes a typical field example of rarely preserved complex structural patterns related to constrictional strain from the deeply eroded central part of the neoproterozoic crustal scale cauvery shear zone system southern india the area exposes intense migmatisation and a distinctive map pattern of a broad domal structure with complex strain patterns the field features such as interfering fold structures extreme hinge line variation domes and basins highly asymmetrical and amoeboid shape structures geometry of foliation trajectories and radial stretching lineations could be related to a single phase of d2 m2 constrictive deformation our observations suggest a close spatial and temporal relationship between transpressive deformation deep crustal melting assent of granite magmas and migmatisation synchronous with d2 m2

quatermalacological analyses for modeling of the upper weichselian palaeoenvironmental changes in the carpathian basin abstract the late pleistocene environmental history of the carpathian basin can be regarded as one of the missing links to our understanding of the last glacial development of europe changes in the radiocarbon dated mollusc faunas of the loess areas along with the palaeogeographic interpretations implied by them seem to underlie the latest results gained from radiocarbon dated pollen analysis of the region changes in the mollusc fauna refer to nine short lived 1000 3000 years cyclical palaeoclimatological alterations which repeatedly transformed the palaeoecological conditions and vegetation in the carpathian basin between 34 and 12 kyr on the basis of malacological data the presence of a major palaeoclimatic trend could be assumed for periods of both warming and cooling in the carpathian basin the mildest july palaeotemperatures were recorded in the sw parts and the coldest ones were recorded in the ne parts of the basin humidity and vegetation cover displayed a large scale mosaic type heterogeneity reflecting the modifying effect of local factors it seem that the upper weichselian environment was mosaic or mosaic like in the carpathian basin and the different plants and animals spread from different ecological spots during periods of climate change when the distribution of the forest grassland ecotone or tundra like habitats changed

deformation partitioning during transpression in response to early devonian oblique convergence northern appalachian orogen usa abstract transpressive deformation was distributed heterogeneously within the central maine belt shear zone system which formed in response to early devonian oblique convergence during the acadian orogeny in the northern appalachians straight belts are characterized by tight folds s l fabrics and sub parallel form lines and asymmetric structures that together indicate dextral se side up kinematics in contrast intervening zones between straight belts are characterized by open folds and l s fabrics within both types of zone metasedimentary rocks have fabrics defined by the same minerals at the same metamorphic grade including a penetrative moderately to steeply ne plunging mineral lineation thus we interpret accumulation of plastic deformation and regional metamorphic re crystallization to have been synchronous across the central maine belt shear zone system discordance between inclusion trails in regionally developed porphyroblasts of garnet and staurolite and matrix fabrics in straight belt rocks records shortening by tightening of folds and greater reorientation of matrix fabrics with respect to porphyroblasts kinematic partitioning of flow was responsible for the contrasting states of finite deformation recorded in the central maine belt shear zone system perturbations in the flow were caused by serially developed thrust ramp anticlines in the stratigraphic succession immediately above the avalon like basement at which decollement of the shear zone system was initially rooted general shear deformation at the ramps involved strain softening with an enhanced component of noncoaxial flow in contrast deformation during extrusion in the intervening zones involved strain hardening with a greater component of coaxial flow part of the thickening stratigraphic succession exceeded tsolidus reflected by the occurrence of migmatites and granites the latter were partly sourced from the underlying avalon like basement that was involved in the deformation and melting

the loess paleosol sequence of basaharc hungary revisited mollusc based paleoecological results for the middle and upper pleistocene abstract the present study discusses the findings of detailed stratigraphical sedimentological geochemical and paleoecological investigations implemented as part of a 1990 campaign to pecsi s studied profile at hungary s important danubian loess profile at basaharc in older studies there were major discrepancies between the old lithostratigraphic classifications and the numerical ages according to the findings of this study the basaharc double paleosol complex described formerly from the lower brickyard as a stratotype of middle wurmian is an isochronous heterotype of the mende upper paleosol complex from profile 1 due to reworking however the lower member of the mende upper paleosol complex must have formed not at the boundary of the upper and middle wurmian as originally presumed but during the riss wurmian interglacial conversely the upper member of this same complex developed during an interglacial between the upper and middle wurmian implying the presence of a huge erosional hiatus between the two members of the paleosol complex the genetics of the individual paleosol layers needs a re evaluation as well the majority of the soils formerly conceived to be of steppe and forest steppe origin developed among closed woodland conditions

finite strain effects in experimental mullions 1986 abstract mullions are cylindrical structures developed at the interface between rocks of different competence shortened along the layering natural examples include phyllosilicate rich meta igneous sheets and massive sulfides in silicate country rocks in axial profiles they consist of rounded lobes convex into the less competent material which alternate with sharp cusps pointing toward the more competent material mullions have been produced experimentally in incompetent single layers of silicone putty viscosity l 2 9 x 104 pa s and power law exponent n 1 embedded in a strain rate softening host of plastilina silicone putty mixture h 5 5 10 pa s and n 7 1 the initiation development and changes in geometry of mullions in the two interfering interfaces of a single incompetent layer shortened along its length by pure shear are reported up to 10 bulk shortening bs gentle flexures develop first in one interface then by 17 bs in both these rounded irregularities become cuspate at 25 bs where a lobe develops on one contact a cusp is slightly preferred on the opposite side such antisymmetric mullions contrast with the symmetrical pinch and swell mullions predicted by smith but are like natural examples and those figured in the literature the amplitudes of the cusps increase while their wavelength range decreases with finite shortening it has been found that mature cusps distort but do not transgress the original contact even if the viscosity contrast is 1 1000 beyond 40 bs cusps either mature to flames or combine to horns and after 60 bs even the last surviving mullions cease to amplify dynamically and the layer only thickens uniformly most stages seen in the models can be matched by natural field examples

molluscan fauna from the loess series of bohemia and moravia abstract in the european context the malacofaunas from the loess series in bohemia and moravia provided relatively rich evidence of environmental conditions in distinct phases of the climatic cycle this is particularly true of the last interglacial glacial cycle in which a number of minor documented phases have made it possible to reconstruct the sequence of detailed environmental changes the major conclusions may be summarized as follows 1 loess malacocoenoses differ in their composition from all known molluscan assemblages in present day europe and show a relatively uniform character in space and time 2 they reflect specific environments that may be called as loess steppe characterized by severe cold continental climate grassland with discontinuous turf cover and raw soils rich in salts 3 malacocoenoses of the loess steppe differ considerably from those of the modern subpolar zone 4 differences in species distribution correspond to particular loess facies due to various depositional and climatic conditions 5 loess is the product of pleniglacial phases in early glacial phases its occurrence is very limited and the malacofauna of these loess horizons is characterized by an absence of most subpolar or alpine species 6 interstadials of the early glacial phase are characterized by assemblages of the chernozem steppe and indicate strongly continental conditions 7 in the pedocomplex i pk i 18 o stage 3 stillfried b no malacological records are available which would indicate a warmer climate its assemblages are very similar to those from the loess 8 interglacials have fully developed woodland malacocoenoses which reflect a warm and humid climate even in areas where such assemblages did not develop during the postglacial 9 loess formation and specific loess malacocoenoses decline in the earlier phase of the late glacial being gradually replaced by much more diversified communities with a higher proportion of moisture loving elements 10 the above mentioned development corresponds to the situation in dry loess areas that may be considered typical loess landscapes at higher elevations and in moister areas different sediments soils and molluscan assemblages existed at the same time their correlation with sequences of the loess series is poorly documented due to the lack of reliable fossil and stratigraphic evidence

stretching lineations in transpressional shear zones an example from the sierra nevada batholith california abstract ductile shear zones and associated stretching lineations are generally considered to be the result of two dimensional simple shear deformations with stretching lineations interpreted to rotate into parallelism with the direction of tectonic transport with increasing deformation however stretching lineations perpendicular to the inferred tectonic transport direction are displayed by some shear zones field studies in the sierra nevada batholith have revealed a single shear zone the rosy finch gem lake shear zone that contains both steeply plunging stretching lineations in older metamorphosed sedimentary and granitic rocks and shallowly plunging stretching lineations in syntectonic granitoids dextral sense of shear indicators are found in all these units and deformation occurred simultaneously along the length of the shear zone theoretical strain modeling indicates that stretching lineations can be either horizontal or vertical within transpressional shear zones to investigate the kinematics of three dimensional deformation we examine the role of stretching lineations which form as a result of finite strain including the possibility of partitioning a component of the strike slip movement onto shear bands comparing the field data with the strain modeling we interpret the along strike variation in lineation behavior within the rosy finch gem lake shear zone to be a result of the differences in finite strain recorded by different units the older units showing steeply plunging lineation have recorded more finite strain across a narrower shear zone than the syntectonic granites which record shallowly plunging lineations we conclude that the orientation of the lineation within transpressional shear zones does not necessarily correlate with the transport direction but may reflect along strike variations in finite strain and or strain partitioning

strain development and kinematic significance of the alpine folding on andros western cyclades greece abstract the general trend of both fold axes and stretching lineation in the cycladic blueschist unit is ne sw to nne ssw this orientation forms a large angle almost perpendicular with respect to the hellenic trend that is inferred from the main thrusts on mainland greece thus the kinematic significance of the stretching parallel folding in the cycladic blueschist unit is non trivial since within the western cyclades the ne trending folds are best exposed on the island of andros it is a key locality for understanding the timing style and kinematic significance of folding here we show that the ne trending folds on andros formed within the stability field of glaucophane after the peak high pressure metamorphism and simultaneously with the early stage of retrogression the axes parallel stretching was non rotational it started during the ne folding at blueschist facies conditions and continued long afterward and well into the retrograde greenschist overprint furthermore we present the result of a finite strain calculation which shows that the large ne folds could not have been reoriented at 90 as previously thought instead it is suggested that these folds formed under constrictional strain regime during regional ne sw extension and represent coeval transverse nw se shortening and vertical thinning this implies that ne extension and southwest directed rollback of the active margin prevailed in the western aegean between the eocene and early miocene

experimental folding and boudinage under pure constrictional conditions abstract constrictional folds are characterized by true fold axis parallel extension if the rock volume does not vary during deformation studies of such folds in experiments using plasticine layers of different apparent viscosity and power law exponent clearly indicate that fold axis parallel stretch may be accompanied by plastic elongation as well as boudinage of the competent layer characteristic aspects of the experimentally folded competent layers are 1 coeval development of folds and boudins 2 layer thickness not changing during deformation 3 layer parallel shortening in sections perpendicular to the fold stretching axis 4 enlargement of the initial thickness of the competent layer results in increasing fold wavelength and decreasing number of boudins the ratio of dominant wavelength to layer thickness of the constrictional folds can be described mathematically approximately by the equation developed for plane strain folding of power law materials

coeval folding and boudinage in four dimensions scaled analogue experiments have been carried out incrementally to demonstrate the growth of constrictional folds and boudins through space and time pure constriction acted on a single stiff layer that was embedded in a weak matrix with the layer trending parallel to the x axis of the constrictional strain ellipsoid the viscosity ratio between non linear viscous layer and matrix was set at ca 13 three dimensional images of the incrementally deformed layer have been obtained using computer tomography they yielded clear evidence that d1 folds and d1 boudins show striking interactions when growing simultaneously at low to moderate finite strain the axes of d1 folds are subparallel and the axes of d1 boudins are subperpendicular to the x axis of the constrictional strain ellipsoid the normalized wavelengths of d1 folds and d1 boudins and the amplitudes of d1 folds are fixed already at low finite strain 5 and do not significantly change as deformation proceeds the normalized wavelength of both structures is not so in line as suggested by theoretical studies at higher degrees of finite strain d1 boudins are affected by d2 folds and rotated limbs of the latter show d2 boudinage resulting in complex deformation patterns that are difficult to identify in the field the model results are important for the analysis and interpretation of deformation structures in rheologically stratified rocks undergoing dislocation creep under bulk constriction tectonic settings where constrictional folds and boudins may develop simultaneously are stems of salt diapirs subduction zones or thermal plumes

constraints on rheology of obsidian lavas based on mesoscopic folds the geometry of mesoscopic single and multiple layer folds in rhyolitic obsidian flows is investigated folds are composed of obsidian embedded in a matrix of pumice folds form by buckling processes as indicated by discontinuous deformation between obsidian and pumice layers and by the geometries of wavetrains buckling occurs through a continuum of styles controlled largely by the thickness ratio of pumice to obsidian n styles of folds include chevron harmonic polyharmonic disharmonic and single layer assemblages harmonic and chevron folds are observed for small values of n for large values of n folds buckle independently of one another and form disharmonic and single layer assemblages wavelength to thickness ratios of single layer folds are compared to theoretically predicted ratios for newtonian and power law fluids as a means of estimating shear viscosity ratios of obsidian and pumice while all folds indicate that bubble free rhyolite is more viscous during flow than bubbly rhyolite estimates of shear viscosity ratio based on newtonian theory 010 500 may exceed estimates based on power law rheologies by more than an order of magnitude newtonian buckling theory involves a number of simplifications and does not account for the possibly complex rheology of bubble bearing rhyolite 1999 elsevier science ltd all rights reserved

high resolution record of the last climatic cycle in the southern carpathian basin surduk vojvodina serbia abstract high resolution study of the surduk loess palaeosols sequence in serbia vojvodina has been performed within a research project eole focusing on the impact of rapid climatic changes during the last climatic cycle in the european loess belt the methodology used for this multidisciplinary approach is based on a continuous sampling column that allows a very accurate correlation between all studied proxies magnetic susceptibility grain size and organic carbon and the dated samples irsl 14 c according to the stratigraphical and sedimentological data the surduk loess sequence appears as a very complete record of the last climatic cycle 19 m and exhibits a similar pattern than other contemporaneous loess sequences from western central and eastern europe the main difference is the evidence of a drier environment all over the last climatic cycle sedimentological and palaeopedological data the high resolution grain size record 5 cm is well correlated with stratigraphical boundaries and highlights a strong variability within the loess deposition especially during the upper pleniglacial between ca 33 and 15 ka during the upper pleniglacial a succession of millennial timescale events characterised by the deposition of coarser loess are particularly well evidenced by grain size data as in some west european records finally an attempt to correlate the variations of grain size parameters at surduk with the greenland grip dust record is proposed according to this study millennial timescale climatic events that characterise the north atlantic area during the last climatic cycle have thus been recorded in the environments located at the southern border of the european loess belt

interfering folds in constrictional deformation abstract experiments on buckle folding indicate that in pure constriction 2 3 2 3 there is an association of domes and basins with nonplane noncylindrical folds the areas of domes and basins are reduced with increasing deformation there is a dominant fold trend perpendicular to 3 with a less dominant trend perpendicular to 3 folds at an angle to these two sets may also occur the divergent folds link up in smooth arcs or join up at a dome or a basin over a relatively large domain the interference pattern produced by general constriction can be recognized by the association of domes and basins with nonplane noncylindrical folds by occurrence of hair pin bends of hinge lines of open folds by occurrence of amoeboid outcrop patterns and by absence of a consistent overprinting relation among different sets of folds layers subparallel to the 3 axis of general constriction may give rise to two or more sets of coaxial cylindrical folds with orthogonal axial surfaces

can field data constrain rock viscosities abstract in the 1960s it looked as though the ratio of wavelength to thickness of folds along shortened competent single layers might allow constraint of the viscosity ratios between the layers and their hosts when they deformed together in the 1970s the possibility arose that simple field measurements of boudins and mullions might also constrain rock viscosity ratios and thereby distinguish deformation facies and map rock viscosities in pressure temperature time space even more potential tools for constraining rock viscosities appeared in the 1980s but since then progress appears to have stagnated in a welter of problems an attempt is made to refocus attention on direct retrospective measurements of rock rheologies during natural deformations by reviewing the potential field tools for constraining rock viscosities discussing some of their problems and by a crude application of the most developed approach further advances are likely to come from iteration between modellers and structural geologists working in a variety of tectonic settings as well as constraining the pressure temperature time paths of our rocks we should also be attempting to measure their viscosities

malacological characteristics of the middle to upper pleistocene transitional interval mis 7 5 observed in the batajnica locality serbia abstract the batajnica loess section is one of the most complete middle and late pleistocene records known in the vojvodina region serbia the main aim of the malacological investigations was to study the latest middle pleistocene cold interval and to see how the mollusc successions reacted to the climate changes during the cold warm transition the deposits which belong to the upper part of pedocomplex v s2 v l2 loess and partly to the v s1 soil were sampled the penultimate glacial loess v l2 of the batajnica site corresponds to the cold interval marine isotope stage mis 6 the molluscs indicate moderate or sometimes warm climate and dry or moderate steppe like environment composed of adjacent mosaics of drier and humid habitats the mollusc complexes of v s2 soil mis 7c v l2 loess mis 6 and v s1 paleosol mis 5e show almost the same species composition which suggests the existence of a comparatively moderate or warm climate during the late middle pleistocene cold interval in contrast the mollusc complexes mis 6 from western and eastern europe have less species and few individuals compared with the batajnica section comparison with the late middle pleistocene mollusc associations from the northern and southern margins of the fruska gora mountain confirms its environmental originality the northern side of the mountain was characterized by a humid and relatively colder environment than the other areas of the vojvodina region batajnica irig and ruma the mollusc fauna obtained in the batajnica site suggests that this adjacent area represented a refugium for the thermophilous and arid tolerant species where they were able to survive during the cold periods of the pleistocene and thus confirms the hypothesis of p sumegi

pleistocene environmental dynamics recorded in the loess of the middle and lower danube basin abstract the substantial loess deposits of the middle and lower danube basin in southeastern europe represent one of the thickest and most comprehensive terrestrial palaeoenvironmental records on the continent yet are also the least well understood environmental conditions over the last million years have resulted in relatively continuous deposits uninterrupted by glaciation and tundra conditions which nevertheless reflect oscillations between relatively warm humid interglacial and cold dry glacial intervals this relative environmental stability may have proven important for hominins migrating into and through the region the loess stratigraphy comprises distinct loess paleosol sequences reflecting glacial interglacial phases which can be quantified for intensity using environmental magnetism and geochemistry these phases are emphasised by variations in vegetation and malacofauna which respond to climatic change the loess deposits demonstrate broadly similar sedimentological characteristics across the basin danubian loess deposits initiated in response to the tectonic formation of the pannonian basin retreat of the large palaeolakes and increased sediment supply from the danube the period from 1 ma 500 ka mis 27 13 was characterised by alternating loess deposition and pedogenesis during glacial and interglacial periods respectively in response to relatively humid forested conditions this period represents the opening of the danube corridor and provides the backdrop for initial hominin arrival into europe after 500 ka and particularly after mis 9 loess accumulation rates increased in response to relatively more steppic arid environments mis 9 and 13 15 were the most humid phases of the last 600 ky the mis 5 interglacial period was the warmest and relatively most humid period preceding the holocene and was followed by substantially increased loess accumulation during mis 4 which may be linked to north atlantic circulation the complexity of the mis 3 interstadial paleosol suggests that conditions were not uniformly warm and wet during this time mis 3 corresponds with the first arrival of anatomically modern humans to europe the last glacial maximum and younger dryas of mis 2 were characterised by substantially increased loess accumulation indicating cold steppe environments most likely influenced by the north atlantic although conditions were sufficiently mild that the region acted as a refugium for thermophilic biota as may also have been the case for most of the pleistocene glacial cycles the holocene soil represents relatively wamer and more humid conditions corresponding to the current interglacial

the dniesterian mousterian from the velykyi glybochok site related to palaeoenvironmental changes the velykyi glybochok multicomponent open air palaeolithic site is situated in podolia western ukraine in addition to the final palaeolithic and upper palaeolithic cultural layers three middle palaeolithic ones were discovered in a sequence of loess with fossil soils covering neogene limestones exposed in a local quarry the present paper discusses the characteristics of archaeological materials found in the site as well as the main results of the geological palaeopedological and palaeontological mammals and molluscs investigation they are used for reconstruction of the past environment changes and stratigraphical interpretation the oldest cultural layer iii is connected with the korshiv fossil soil in ukrainian nomenclature of the penultimate interglacial mis 7 layer iii b with the ternopil horizon corresponding with climatic amelioration during the penultimate glacial mis 6 and layer iii a with the gorohiv fossil soil originated during mis 5 in the western part of eastern europe outside the carpathians several mousterian sites dated to the last interglacial are known but velykyi glybochok is the only site where palaeolithic settlement dated to mis 7 and 6 is documented the participation of levalloisian elements is characteristic for artifacts of all the middle palaeolithic mousterian cultural assemblages of velykyi glybochok this suggests a local origin of the dniesterian mousterian culture with the levalloisian technique of stone flaking

biostratigraphy of the late middle pleistocene middle neopleistocene of the southern urals region abstract a summary of published and unpublished materials on the stratigraphy of the late middle pleistocene middle neopleistocene according to the russian stratigraphic scheme of the southern urals region is given deposits of different origin in the regional stratigraphic units are characterized the results of mammalian investigations provide the basis for the stratigraphical subdivision mollusca and palynology are used for the reconstruction of the palaeoenvironments the stratigraphical positions of the main middle neopleistocene localities and precise definitions of the stratigraphical scheme of the southern urals region are discussed the southern urals subdivisions are correlated with the western european stratigraphical schemes holsteinian saalian interval

abrupt millennial climatic changes from nussloch germany upper weichselian eolian records during the last glaciation abstract increasing attention has been focussed on the massive iceberg discharges in the north atlantic heinrich events during the last glaciation and their worldwide terrestrial counterparts however these events are particular episodes among more regular cyclic events named dansgaard oeschger events in ice cores or bond cycles in marine cores here we examine grain size 13c and magnetic susceptibility data from nussloch one of the most complete west european eolian sequence examined so far these indices indicate that during the 31 19 kyr interval using chronology provided by radiocarbon osl and tl dates millennial scale variations occurred affecting both precipitation and vegetation furthermore these are associated with oscillations in the wind strength matching the dust deposition rate in greenland as recorded in the grip ice core our study shows that the abrupt climatic changes the dansgaard oeschger events are also recorded in the west european loess sequences this implies an atmospheric mechanism linking dust deposition over greenland and europe which is probably connected to global climatic events during the last glaciation

climatic conditions recorded by terrestrial mollusc assemblages in the chinese loess plateau during marine oxygen isotope stages 12 10 abstract past analogs for our present interglacial have been sought for better understanding of our present and future climate marine isotope stage 11 mis 11 has long been considered to be a good candidate and has gained increasing attention in recent studies of marine and terrestrial records in the chinese loess paleosol sequences s4 soil interpreted as equivalent to mis 11 yields a very precise terrestrial paleoclimate record of environmental changes that prevailed during this period in this study two high resolution terrestrial mollusc records from the loess plateau have been analyzed to characterize climate variability during the periods of mis 12 10 the changes in environment and climate indicated by the variations in abundance of land mollusc species are thus documented our mollusc results show that the l5 loess equivalent of mis 12 developed under relatively cold and dry conditions climate during this period was not as severe as indicated in the marine isotopic records an episode of warmer and more humid condition occurred at the middle stage of the mis 12 reflecting a summer monsoon strengthened during the glacial interval a similar scenario has been observed in the middle part of mis 10 in addition our mollusc records provide insight into the climate conditions over the loess plateau during mis 11 a general warm humid climate dominated during the formation of s4 soil but at least four fluctuations occurred at xifeng region reflecting unstable climate conditions and regional climate differences within the loess plateau during this period our study shows that the early part of s4 spanning over 30 ka was very warm and humid while the late part was characterized by mild cool conditions comparison of mollusc species compositions of both mis 11 and holocene intervals reveals different climate conditions the early part of mis 11 was warmer and more humid than the holocene optimum period while the late part of mis 11 was similar or cooler our study indicates that the extent of warming during the holocene in the loess plateau might be significantly less than the conditions that prevailed during the mis 11 interglacial period

stratigraphy and chronology of the periphery of the scandinavian ice sheet at the foot of the ukrainian carpathians abstract the article presents the results of research on the formation conditions and the age of glaciogenic deposits left by the scandinavian ice sheet in the eastern carpathian foreland in its part drained by the dniester river and its tributaries black sea basin these deposits till erratics glaciolacustrine and glaciofluvial sediments preserved only in some places and occurring in the range of altitudes defined by terrace vi early pleistocene and terrace v middle pleistocene are the southernmost traces of the ice sheet in europe they are underlain by fluvial deposits and overlain by loess deposits and locally occur as intraloess layers the following research methods were used geomorphological mapping sedimentological lithological micromorphological palaeopedological and palaeontological analyses as well as luminescence dating the obtained results allowed a reconstruction to be made of the main stages of morphogenesis and the style of the ice sheet advance at its maximum extent defined as the sambor phase the area was glaciated during mis 12 elsterian ii sanian 2 okanian as indicated by the occurrence of a complete middle upper pleistocene loess palaeosol sequence the oldest palaeosol s4 i e sokal mazovian zavadivka soil that developed directly on the glaciogenic deposits or loess l5 is correlated with the holsteinian likhvinian interglacial mis 11

did bushmanland extensionally unroof namaqualand abstract the namaqua natal orogen evolved between about 2000 and 1000 ma as part of an orogenic system that assembled the rodinian supercontinent and wraps the archaean kaapvaal craton to the south and west the orogen includes the western ultra high temperature sapphirine hercynite granulite facies namaqualand terrane structurally overlain to the north by the low grade high level igneous richtersveld terrane 1900 1700 ma and to the east by the amphibolite facies granite gneiss pb zn rich supracrustal bushmanland terrane which is overthrust from the north along the groothoek thrust by the high pressure hom terrane west of the dextral tantalite valley pofadder shear zone the gently dipping contacts among these terranes have been considered to be thrusts with the exception of the groothoek thrust the contacts are low angle top down to the east or northeast folded extensional detachments with displacements of up to at least 100 km the namaqualand part of the namaqua natal orogen comprises two distinct event sequences a kibaran phase of crustal shortening and thickening and voluminous granitic sheets at about 1200 ma then a namaquan phase of mafic underplating ultra high temperature metamorphism granitic sheets dextral transtension constrictional fabrics and crustal thinning from about 1060 to 1030 ma a dominant constrictional ls fabric was developed in regionally sub horizontal layered pink granite gneisses and metasediments deformed by ene trending folds extensional detachments developed late in the namaquan phase when the ultra high temperature rocks were exhumed in the bushmanland terrane aggeneys metasediments have mainly constrictional fabrics and are deformed by giant upward facing downward closing sheath folds developed during transtension in which lie 1700 ma pb zn sedex deposits like those of broken hill and flin flon the namaqualand terrane may be the largest and oldest extensional core complex on earth the proterozoic era was characterized by transtensional ultra high temperature horizontally layered lineated pink gneiss terrains with corrugating fold hinges roughly parallel with the finite stretching direction

kinematics of rock flow and the interpretation of geological structures with particular reference to shear zones abstract current interpretations of structures are generally based on homogeneous and steady deformation models despite the fact that both the heterogeneity of rocks materially rheologically and geometrically and the time dependence of imposed geological conditions give rise to significant heterogeneous and non steady flow in concert with field observations we emphasize that the expectation of heterogeneity and non steadiness is the key to understanding natural deformation and that in order to carry out successful structural analysis and tectonic interpretation it is necessary to recognize the first order distinction between imposed boundary conditions typically used to define the tectonic regime e g transcurrent transpression and the response recorded by rocks within the zone structures and fabrics using s c fabric as an example it is demonstrated how flow with a non zero spinning component resulting from the rheological contrasts and or geologically realistic time dependent boundary displacement can drastically change the ideal geometric and kinematic relations between the fabric and the host zone in agreement with both theoretical analysis and field observation it is shown that natural flow regimes range from pure shear to pure rotation including super simple shear in consideration of the heterogeneity and non steadiness of natural deformation kinematic analysis is justifiable only within a homogeneous domain and steady period flow kinematics and mechanisms are interrelated in that firstly mechanisms provide internal constraints on kinematics ensuring that only certain flows are possible and secondly flow kinematics will favour development of certain mechanisms

when shearing is a cause of folding abstract numerous publications on shearing as a cause of folding do not refute the idea of buckling being the main process responsible for the formation of fold structures deformations of other types may either produce conditions for layer parallel shortening needed for buckling or modify fold shapes but do not generate new fold structures on any scale the origin of similar folds commonly considered to be a result of inhomogeneous shearing across layering may be explained by buckling of a multilayer where layers have uniform favourable rheological properties tightening and amplification of folds near fault surfaces is not necessarily a result of shearing caused by friction at fault surfaces on the contrary in these cases faulting is a result of strain localization during folding recumbent isoclinal folds so common in metamorphic rocks originate mainly by buckling of subvertical planar structures intrafolial folds are usually very flattened relics of former folds the idea of sheath folds being produced mostly by shearing is not confirmed by the available geological data sheath folds that were not produced by shearing are rather common more likely they are formed by constriction or flattening of folds with curved hinges the latter are a result either of fold interference or of the constriction in the layering plane

constriction structures related to viscous collision southern prince charles mountains antarctica macroscopic structures are investigated in a zone of highly contorted migmatites from the southern prince charles mountains antarctica here l tectonite fabrics rods mullions boudin pods elongate enclaves and fold hinges are persistent linear features all plunging gently to the northeast in contrast amoeboid folds ptygmatic folds and folded boudins with different orientations are the characteristic structures in transverse sections perpendicular to the lineation no consistent shear sense is recognised in any dimension together with strain and shape analysis these observations strongly suggest that the deformation pattern is one of folding and stretching by constriction previous timing constraints indicate that this deformation overlapped with the waning stages of anatexis during decompression at approximately 510 ma up to 30 million years after initial orogeny at 540 ma the zone affected by constriction is several kilometres wide and has a contorted flower like shape confined between two broad domal antiforms in this context the constricted zone is interpreted as a relatively late tectonic feature that could have formed via deep seated viscous collision in response to orogenic collapse and doming

the late pleistocene belotinac section southern serbia at the southern limit of the european loess belt environmental and climate reconstruction using grain size and stable c and n isotopes the belotinac loess section is one of the southernmost loess paleosol environmental archives for the late quaternary in serbia the climate at this site is intermediate between the continental and the mediterranean realms which makes this loess archive potentially highly sensitive to past climatic changes this paper presents new insights into the paleoenvironmental history during the last glacial period in southern serbia using grain size and isotope proxy data the grain size parameters from the belotinac section reveal variations in the paleowind dynamics and weathering intensity and suggest the nearby valley of the ju na morava river as an important source of aeolian sediments in this area based on a multiproxy dataset alternating phases of weak interstadials and phases of enhanced loess deposition at this site were identified nitrogen isotope data suggest that during marine isotope stage 3 ecosystems of high biomass productivity and rather open n cycles prevailed during marine isotope stage 2 productivity was reduced and the n cycle was more strongly closed probably due to a shorter growing season and more pronounced temperature decline carbon isotope data indicate a possible contribution of c4 plants to the holocene vegetation but not to the glacial and interstadial ecosystems of the late pleistocene changes in atmospheric co2 level are not reflected in the carbon isotope record these findings are discussed in the light of paleoclimate proxy datasets from the morava river valley and carpathian basin as well as through comparison of carbon isotope records from loess sections in se central europe and in the rhine valley two different loess provinces exist in terms of glacial interglacial humidity changes a province of glacial drying and a province of glacial humidification the first includes loess sites under more oceanic influence where loess 13c records indicate humid interglacials and interstadials and relatively drier glacial periods the second includes the loess sites of the carpathian basin and especially the southern serbian loess area of belotinac where loess 13c records indicate more intensive aridity during interglacials but a reduced soil moisture deficit and a more humid climate due to lower evapotranspiration in interstadials and even more in glacial periods

weichselian upper pleniglacial environmental variability in north western europe reconstructed from terrestrial mollusc faunas and its relationship with the presence absence of human settlements abstract during the weichselian glaciation millennial timescale climatic changes are a major cause of environmental variability which influence the composition of large mammal fauna and the geographical distribution of human prehistoric populations nevertheless precise environmental contexts of archaeological artefacts may remain unknown due to an unclear stratigraphy and or to the bad preservation of paleoenvironmental proxies as pollen is badly preserved in glacial loess deposits a compilation of age constrained high resolution molluscan records is used to initiate the establishment of a canvas of millennial timescale spatial and temporal environmental changes in the european loess belt during the weichselian upper pleniglacial ca 37 20 ka to look for relationships with spatial distribution of human settlements in this study new terrestrial mollusc assemblages have been added to the database previously established for north western europe they strengthen the position of the limit between the two molluscan based biogeographical domains initially highlighted for north western europe a flat and poorly vegetated western domain extending around the channel and in belgium and a hilly domain with more diversified vegetation to the east the analysis of molluscan data shows the persistence of these two domains throughout alternations of loess deposition phases interstadial stadial transitions and stadial phases with phases of development and degradation of tundra gley horizon stadial interstadial transitions and interstadial phases the interpretation of malacofauna from both domains combined with associated pedological and sedimentological features climate modelling and comparisons with present tundra environments reveals a significant effect of both seasonality and snow cover along a longitudinal gradient between both domains but also between phases of loess deposition and phases of tundra gley development during interstadial phases the intense functioning of the active layer and the degradation of permafrost in north western europe led to more homogeneous environments which were less favourable for the diversity of both vegetation and terrestrial mollusc fauna presently uncertainties of numerical ages still preclude precise correlations of loess units and tundra gley horizons between different sites and with nonlocal prehistoric occupations however a first raw comparison of the molluscan data with spatial distributions of aurignacian gravettian and solutrean upper magdalenian lithic cultures reveals that the northern limit of the first two ones fits well with the south eastern border of the poorly vegetated western domain also characterised by well developed ice wedge networks during phases of permafrost installation later an important southward shift of human populations in western europe resulted from the extreme aridity of the last glacial maximum

stratigraphic position and natural environment of the oldest middle palaeolithic in central podolia ukraine new data from the velykyi glybochok site abstract velykyi glybochok is an important multi cultural palaeolithic site known since 1979 besides the late palaeolithic i and upper palaeolithic ii cultural layers in this site the following middle palaeolithic layers are found iii b in the soil from the last interglacial iii a in the ternopil soil horizon from the penultimate glaciation and iii the oldest palaeolithic settlement in podolia in the soil from the penultimate interglacial the ages of these cultural layers are determined from their situation in a complex sequence of loesses and paleosols in this paper we report the results of excavations carried out in the years 2007 2012 which were supplemented with geophysical recognition the excavations were conducted in a karst depression formed in neogene limestones it is filled and covered by loess containing partially redeposited paleosols these deposits were sampled for lithological palaeopedological palaeomagnetic and palynological analyses the results of which were used for palaeoenvironmental interpretation chronostratigraphy was determined based on tl and irsl dating as well as palaeomagnetic studies in comparison with the older investigations the new discovery is quite well preserved with a bipartite complex of paleosols s2 ii and s2 i from the penultimate interglacial mis 7 which occurs between the odranian dnieper loess l3 and the wartanian tyasmin loess l2 the paleosols are of interglacial nature forest and then steppe vegetation grew during two stages of their formation which were separated by a cool period when a small accumulation of loess and frost processes occurred the oldest middle palaeolithic cultural layer occurs in the older soil s2 ii indicating that it is the trace of the oldest palaeolithic settlement in the western ukraine flint artefacts were made using the levallois method rarely found in the sites with the middle palaeolithic oldest assemblages rare in eastern europe

partitioning of non coaxiality in deforming layered rock masses abstract partitioning of non coaxiality and other flow parameters in deforming layered rock masses with nearly incompressible newtonian rheology is examined in two dimensions by the finite element method the results show that layers with viscosity contrast in suitable orientation deform by different and even by a reverse sense of non coaxiality this remarkable partitioning of non coaxiality is due to a large rotation rate of instantaneous stretching axes in a heterogeneous body as a result of geometry changing through deformation rather than through rotation of material lines

superimposed tectonic events at 2450 ma 2100 ma 900 ma and 500 ma in the north mawson escarpment antarctic prince charles mountains abstract the north mawson escarpment in antarctica s prince charles mountains forms part of a palaeoproterozoic crustal complex which separates archaean cratonic material to the south from early neoproterozoic and early palaeozoic metamorphic belts to the north it consists of nappe like masses of grey gneiss and metasupracrustal rocks that were subjected to repeated ductile deformation under upper amphibolite to lower granulite facies metamorphic conditions in this paper we report zircon u pb dating results that constrain the principal tectonothermal events to the periods 2490 2420 ma 2180 2080 ma 940 880 ma and 530 490 ma the magmatic precursors of volumetrically important grey gneiss were produced and reworked at least partly during the 2490 2420 ma and 2180 2080 ma events the superimposition of these events is clearly documented by u pb ages from several composite zircons the formation of associated metasupracrustals possibly in a passive margin setting occurred between the 2490 2420 ma and 940 880 ma events both grey gneiss and metasupracrustals were subsequently reworked during the 940 880 ma and 530 490 ma events corresponding to the superposition of both the rayner and prydz belts onto palaeoproterozoic lithosphere of the lambert complex transposition and peak metamorphism preceded the intrusion of leucogranite dykes at 905 ma and based on metamorphic zircon growth at around 930 ma in metapelitic schist are related to the rayner orogeny it is suggested that the north mawson escarpment was assembled to most coastal regions of the antarctic sector between 45 and 80 e by at least 900 m y ago

sheath folds as discriminators of bulk strain type abstract nested elliptical closures defining eye folds represent classic y z cross sections through highly curvilinear sheath folds generated during intense ductile deformation in metamorphic rocks systematic analysis of 1425 such eye folds based on our own field observations and examples from the published literature reveals distinct and consistent differences in ellipticites measured from the outer r yz to the inner most r y z elliptical rings of individual sheaths the variation in overall aspect ratios from outer to inner rings is defined as r where r r yz r y z and may display a relative increase or decrease in ellipticity to define cats eye r bulls eye r 1 fold patterns respectively layer thicknesses may also be measured along the y axis parallel to the axial surface t y and at 90 to this along the z axis t z to define the ratio of t yz sheath folds generated during broadly simple shear deformation k 1 display mean r yz 4 61 t yz 3 31 and cats eye folds r 0 69 sheath folds generated during general shear also display cats eye folds with identical mean r 0 69 values but greater thickness variations and elliptical ratios t yz 4 35 r yz 5 76 thus within both simple and general shear dominated deformations the overall variation in layer thickness t yz and ellipticity of eye folds r yz increases with increasing deformation and a greater component of pure shear whilst the r value remains constant and reflects original fold patterns sheath folds formed during constrictional k 1 deformation display markedly lower aspect ratios r yz 2 42 and thickness variations t yz 2 94 together with distinctive bulls eye folds r 1 23 these empirical relationships suggest fundamental and universal constraints on curvilinear fold generation across this broad spectrum of deformation types and allow sheath folds to act as both effective 95 consistent and robust discriminators of bulk strain type

a laterally constricted shear zone system the nordre stromfjord steep belt nagssugtoqidian orogen w greenland many ductile shear zones are interpreted to operate by simple shear flow but some form under other flow regimes lineations and foliations in such shear zones can lie obliquely to those in simple shear zones which can lead to erroneous tectonic interpretations on the assumption of simple shear flow this paper describes a gently dipping shear zone system from the n central segment of the palaeoproterozoic nagssugtoqidian orogen of w greenland which operated with a lateral constriction component this resulted in the development of upright folds with axes parallel to the transport direction where the constriction component is weak where it is strong a linear fabric and even a subvertical foliation normal to the rotation axis of bulk flow developed this steep foliation is interpreted as the origin of the nordre stromfjord steep belt previously interpreted as a crustal scale sinistral transcurrent shear zone shear zones of this type may occur elsewhere and shear zone fabrics should therefore be carefully analysed before the direction of tectonic transpost can be determined

non linear feedback loops in the rheology of cooling crystallizing felsic magma and heating melting felsic rock at least six major parameters control the rheology of partially molten systems melt content rate of melt production reaction to strain of the solid component reaction to strain of the molten component temperature and chemical composition of the source rocks we examine their interactions to understand the rheology of partially molten rocks and partly crystallised magmas this paper especially focuses on the rheology in the transitional domains between two pairs of thresholds that bracket a transitional regime between a solid state and a fluid behaviour during melting and crystallisation respectively we review related information and point out non linear effects that develop during heating of melting rocks and cooling of crystallising magmas owing to the non linear interactions positive or negative feedback loops accelerate or damp the system melt in migmatite experiences shear softening which along with strain partitioning facilitates melt segregation conversely the augmenting number of rigid crystals during cooling increases the suspension viscosity shear hardening which soon inhibits magma movement those effects reinforce the asymmetry between solid to melt and melt to solid transitions they severely contradict the concept of one rheological critical melt percentage valid for both melting and crystallisation transitions fabric acquisition competes with nucleation and crystal growth thus leading to hysteresis of the stress stain rate curves implications to field observations include horizontal magma segregation magma extraction and successive magma intrusions

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

the mantled gneiss domes of kuopio finland interfering diapirs abstract finite strain data from the kuopio mantled gneiss domes are described synclines located between two domes have flattening type strains while those situated between more than two domes exhibit constrictional strains cleavage trajectory patterns show that cleavage tends to parallel the dome boundaries and encloses characteristic points termed cleavage triple points at junctions of synclines the stretching lineation is generally steeply plunging in a mean southwest direction folds range from inclined to reclined their asymmetry is apparently related to irregularities in the cover basement boundary two shear components of the deformation have been deduced from available data the major one is steeply plunging and is well exhibited by cleavage fans steeply plunging lineations and finite strain gradients the second shear component is horizontal as deduced from asymmetric folds and other small scale structures and is controlled by bosses and dimples in the cover basement boundaries the described structural features are explained in terms of interference between progressively inflating neighbouring diapirs furthermore some of these features such as cleavage triple points flattening between two domes and constriction between three or more domes and horizontal shear components controlled by cover basement boundary irregularities could be used as criteria of diapirism a model of progressive dome interference is presented in which each dome inflates and interacts with neighbours such a model could possibly be applied to other orogenic situations with closely spaced diapirs e g archean greenstone belts or granite rich orogenic belts

paleoclimatology of the achenheim series middle and upper pleistocene alsace france a malacological analysis abstract the loessic series of achenheim show an uninterrupted stratigraphical sequence dating from the middle and upper pleistocene they contain very abundant paleontological material especially land snails statistical analysis of the malacofaunas multivariate methods has allowed the reconstruction of the climatic evolution of that site during this period five cycles have been recognized which correspond to the glacial cycles b c d e and f comparison with the section of cerveny kopec czechoslovakia indicates the existence of a major climatic event during the pleniglacial of cycle d with a general expansion of the loess steppe in europe an environment which later never appeared in alsace the analogy of the climatic sedimentary sequences of cycle c suggests that alsace and central europe belong to the same geographical entity the development of alsace to an intermediary status between northwestern and central europe

malacological sequence from profile of calcareous tufa in gron podhale basin southern poland as an indicator of the late glacial holocene boundary abstract rich assemblages of subfossil malacofauna were discovered in the profile of slope deposits and calcareous tufas at the gron site in the podhale basin in southern poland the detailed analysis of the composition of this fauna has made it possible to distinguish four types of assemblages their age was established by radiocarbon dating as well as by comparisons with other profiles the malacofauna represented almost exclusively by terrestrial species was used for the reconstruction of the changes in the environment during the sedimentation of the deposits the assemblages distinguished in the study provided the basis for stratigraphic considerations the oldest fauna characterized by a high proportion of cold loving species is typical of the younger dryas the remaining three assemblages are correspondingly linked with the early and middle holocene the evident differences in the composition and structure of the identified malacocoenoses enabled definition of the late glacial holocene boundary the wide geographical distribution of the selected molluscan assemblages enables supra regional correlation and provides an important premise for defining the regional malacostratigraphic subdivisions which can be successfully used to determine the age of deposits from this viewpoint the profile of calcareous tufas in gron represents a model location for central europe

late pleistocene environments of the central ukraine the vyazivok loess sequence from the dnieper plain ukraine documents regional environmental changes during the late pleistocene and holocene pedological and palynological analyses and low field magnetic susceptibility document changes from dense temperate forest during the last interglacial maximum to open harsh loess steppe during the latest pleistocene the vyazivok section overlies hillwash derived from a lower pleistocene terrace and consists of two stratified soil complexes kaydaky and pryluky marine isotope stage mis 5 equivalent separated by a layer of eolian dust tyasmyn silt the lower soils in both complexes formed within forest these soils are overlain by the uday mis4 and bug mis2 loess units which are separated by boreal soils of the vytachiv mis3 complex the coldest conditions within the record occurred in the youngest loess holocene soils cap the bug loess the vyazivok section shows remarkable similarities with other classical loess sequences in western europe the czech republic and austria the kaydaky pryluky and vytachiv deposits correlate with the pkiii pkii and pki soil complexes respectively of the czech republic the tyasmyn and prylyky silt layers correspond to marker horizons from central europe c 2001 university of washington

high resolution record of the last interglacial glacial cycle in the nussloch loess palaeosol sequences upper rhine area germany the nussloch loess sequences were sampled at close intervals 10 cm and documented in respect of their stratigraphy palaeopedology sedimentology palynology malacology and geochemistry and were dated using radiocarbon and osl methods for each stratigraphic unit the results of both the eld studies and the analytical and geochronological data obtained cast light upon the response of the loessic environment to global climatic variations during the last cycle the basal soil complex underwent a pedosedimentary evolution similar to those of the bordering area complex luvisol greyzem steppe soila which re ects the classic progression towards increased continentality of the environment between the end of the eemian 5d and the beginning of the full glacial stage pleniglacial the lower pleniglacial corresponds to an initially very arid phase dominated by the accumulation of loess followed by the deposition of strati ed niveo eolian sands the middle pleniglacial complex ca 55 30 is clearly characterised by the inhibited loessic sedimentation it is primarily marked by two phases of stabilisation recorded in the form of weathered horizons cambisols which are separated by a rather thin layer corresponding to loessic sedimentation with tundra gleys this intermediate phase brings together organic silt deposits which record an interstadial dated at 32 33 ka c bp the thick loessic accumulations of the upper pleniglacial 10 m which clearly began to accumulate before the oxygen isotope stage ois 3 2 boundary show evidence of vulnerability to considerable uctuations in response to variations in wind dynamics and the intensity of de ation in the rhine valley finally a proposed correlation of loess palaeosol stratigraphies from germany belgium and france spanning the entire last interglacial glacial cycle is presented 2001 elsevier science ltd and inqua all rights reserved

pleistocene interglacials and glaciations of northeastern poland compared to neighbouring areas abstract the pleistocene stratigraphy of northeastern poland is based mainly on palynological analyses of organic lake sediments and their palaeomagnetic dating as well as on the lithological petrographical analyses of tills and intervening deposits these data were collected from the most recent boreholes drilled for the detailed geological map of poland on a scale of 1 50 000 in northeastern poland there are eight to eleven glacial beds based on geological and lithological petrographical evidence they are presumably represented by tills of eight glaciations the narevian menapian nidanian glacial a cromer complex sanian 1 elsterian 1 sanian 2 elsterian 2 liviecian fuhne odranian or krznanian drenthe wartanian warthe and vistulian weichselian substantial palynological evidence exists for organic sediments of the augustovian bavelian complex or cromerian i mazovian holsteinian and eemian eemian interglacials the age determination of the zbojnian domnitz interglacial on organic sediments in the raczki wielkie borehole near olecko is based on tl dating and incomplete palynological analysis only the other interglacials known from central and southern poland the malopolanian cromer complex ii or iii interglacial ferdynandovian voigtstedt and lubavian karlich have no palynological evidence in northeastern poland or its geological position and age losy profile near lubawa are under discussion the ferdynandovian voigtstedt and lubavian karlich interglacials are presumably mostly represented by lake and fluvial facies

shear zones between rock units with no relative movement abstract shear zones are normally viewed as relatively narrow deformation zones that accommodate relative displacement between two blocks that have moved past each other in opposite directions this study reports localized zones of shear between adjacent blocks that have not moved past each other such deformation zones which we call wakes form due to the movement of exotic blocks within a viscous medium denser blocks sinking within a salt structure the paths between separated boudins melt in partially molten surroundings melt movement during migmatisation or solid blocks sinking through a partially molten magma body stoping from the fluid dynamics perspective these shear zones can be regarded as low reynolds number deformation zones within the wake of a body moving through a viscous medium while compact moving bodies aspect ratio 1 1 1 generate axial symmetric cone like shear zones or wakes elongated bodies vertical plates or horizontal rod like bodies produce tabular shear zones or wakes unlike conventional shear zones across which shear indicators usually display consistent symmetries shear indicators on either side of the shear zone or wake reported here show reverse kinematics thus profiles exhibit shear zones with opposed senses of movement across their center lines or planes we have used field observations and results from analytical and numerical models to suggest that examples of wakes are the transit paths that develop where denser blocks sink within salt structures bodies of melt rise through migmatites between boudins separated by progressive extension and perhaps where slabs of subducted oceanic lithosphere delaminate from the continental crust and sink into the asthenosphere we also argue that such shear zones may be more common than they have been given credit for and may be responsible for some reverse kinematics reported in shear zones

the matuyama brunhes boundary and the nature of magnetic remanence acquisition in the loess palaeosol sequence from the western part of the east european loess province abstract loess palaeosol sequences from the western part of the east european loess province were palaeomagnetically studied the position of the matuyama brunhes boundary was found in the sequence at zahvizdja east carpathian foreland overlying the surface that corresponds to the vi dniestre terrace this boundary is located within the accumulation horizon of an interglacial soil developed during the time equivalent of oxygen isotope stage 19 the lowermost palaeosol of this sequence located just below the soil containing the matuyama brunhes boundary record can thus be correlated with oxygen isotope stage 21 and the vi dniestre terrace was developed during oxygen isotope stage 22 samples from the palaeosols especially from their accumulation horizons revealed the presence of secondary postdepositional components of magnetisation some resistant to alternating field demagnetisation even as high as 100 mt fine grained maghaemite is most probably the carrier of these components subsequent thermal demagnetisation can remove them to establish the primary palaeodirections haematite and magnetite are the main carriers of remanent magnetisation of the loess layers the degree of possible delay of remanence acquisition in loess sequences was assessed on sediments from three sections sampled in the volhynia and lublin uplands good correlation of directional changes recorded in coeval segments of loess sections shows that the characteristic magnetisation of aeolian deposits from the western part of the east european loess province is approximately syndepositional

loess in a cave lithostratigraphic and correlative value of loess and loess like layers in caves from the krakow czestochowa upland poland abstract although debris loams and clays are usually regarded as typical cave sediments loess and loess like sediments are common among clastic cave deposits in the near entrance facies of caves and rock shelters late weichselian loess layers are very common in caves from the krakow czestochowa upland and were recognized in almost each excavated cave and rock shelter these layers were initially dated to the lgm last glacial maximum but new chronometric dating results are available that allow us to present a more detailed scheme of the geological age of the series this paper evaluates the significance of polish in cave loess layers as correlative horizons we present the lateral and vertical stratigraphy and lithological variability of cave loesses and their usefulness as lithostratigraphic markers these features are especially important for archeology and paleontology as cave sediments including loess are usually the carriers of archeological and paleontological material

molluscs and ostracods of the pleistocene loess deposits in the halych site western ukraine and their significance for palaeoenvironmental reconstructions abstract middle and late pleistocene loess palaeosol sequence mis 12 mis 2 from the halych site has been divided into four loess beds which represent different glacial periods and contain four interglacial pedocomplexes as well as numerous interstadial and interphase palaeosols long term interdisciplinary research which has been conducted in this site enables the detailed description of deposit lithology and precise determination of stratigraphic position of individual layers rich and diverse malacofauna occurs in loess deposits representing cold stages mis 12 mis 8 and mis 4 2 seven molluscan assemblages of diverse composition and structure have been distinguished additionally ostracod fauna from the deposits representing mis 8 is described faunal investigations enable the reconstruction of environmental changes during deposition of the studied sequence the obtained results indicate that the halych site may be considered as very important not only for the reconstruction of the pleistocene geological history in western ukraine but also for the studies of environmental conditions during the middle and late pleistocene in the whole of central and eastern europe

the importance of incompetence metabasaltic dikes that are known to be competent and to deform more slowly than granitoid country rocks in the upper crust are likely to be incompetent and deform faster than granitoid hosts in the higher temperatures of the lower crust layers that deform as competent strain markers develop inward pointing cusps these deformation structures are called folds in shortened layers and necks in extended layers and are reasonably well understood by contrast layers that deform as incompetent markers develop strong internal foliations and outward pointing cusps these structures are currently known as mullions in shortened contacts and inverse folds in extended contacts but are comparatively poorly understood here we emphasize the importance of the deformation structures in the incompetent hydrated metabasaltic intrusions and enclaves that must be among the structures that seismic reflection profiles attempt to image deep in the continental crust

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

molluscs in loess their paleoecological significance and role in geochronology principles and methods abstract the malacofauna of genuine wind blown loess consists of a minor number of tolerant species occurring mostly in high amounts and reflecting open habitats with poorly developed calcareous soils it shows a rather uniform character in space and time distinctly differing from all present day assemblages of the temperate zone and thus indicating a very peculiar environment characteristic of the loess steppe in protected areas particularly on valley slopes the loess covers alternate with intercalations of slope sediments and soils including several other types of snail assemblages reflecting environmental changes in the course of the quaternary climatic cycle among these malacocoenoses the interglacial faunas are of prime biostratigraphic importance they are associated with strongly weathered forest soils and indicate woodland environments under very damp and warm climatic conditions transitional steppe and taiga assemblages occur in buried chernozem soils and in various slope sediments e g in the pellet sands overlying the interglacial soils and corresponding to early glacial periods although the fauna of proper loess shows a monotonous composition it is possible to distinguish several types of loess assemblages corresponding to minor facies changes of loess environments in time and space these are for example the pupilla helicopsis striata and columella faunas of central europe a peculiar marshland fauna characterizes the so called swamp loess deposited in ephemeral swamps in the marginal zones of the loess belt there occur also faunas partly differing from those of typical loess this is true particularly of the mediterranean region the most important contribution provided by molluscan faunas from the loess series is the evidence of the maximum number of climatic cycles during the quaternary period

the partitioning of deformation in flowing rock masses abstract most geological structures owe their development to heterogeneous and or non steady flow flow partitioning refers to the division of the instantaneous velocity field into components related to translation strain and rotation flow partitioning during the development of a geological structure usually changes with time and different histories of flow are involved at different points in the developing structure heterogeneity leads to the development of flow domains with different characteristics notably the degree of non coaxiality of deformation and different partitionings of the rotational component of flow into shear induced vorticity and spin during non steady flow there is often continual repartitioning of vorticity between the spin and shear induced components spin is an important aspect of flow leading to the development of structure this paper discusses the partitioning of deformation in a flowing rock mass coaxial flow tends to occur in isotropic materials in regions near weakly constrained boundaries non coaxial flow is favoured by suitably oriented material anisotropy and or the presence of well defined boundary constraints involving parallel relative displacements a developing anisotropy e g a crystallographic fabric in a shear zone can induce a change from coaxial to non coaxial flow other effects are related to the scale of approximation for example bulk shear induced vorticity can be locally converted to spin flow in the crust and mantle of the earth produces geological structures on all scales and involves many different types of rheological response the factors that affect flow partitioning e g spin versus non coaxial deformation are therefore of interest

an introduction to the middle and upper pleistocene loess paleosol sequence at ruma brickyard vojvodina serbia abstract six loess units and five paleosols are preserved in the 20 m thick exposure of middle and late pleistocene sediments at ruma brickyard vojvodina serbia amino acid geochronology provides stratigraphic correlations between loess paleosol units sl l1 s1 sl l2 s2 sl l3 s3 and sl l4 at ruma with loess of glacial cycles b c and d and e respectively at other central and southeastern european localities the profile represents one of the best potential sections in the region for reconstructing detailed paleoclimates and paleoenvironments of the last ca 350 000 yr initial sedimentological magnetic and malacological evidence indicate many episodes of drier conditions in the region than in other parts of central and southeastern europe during the later part of the middle and late pleistocene

loess biostratigraphy new advances and approaches in mollusk studies abstract since the beginning of the 20th century loess biostratigraphy has been strongly influenced by investigations of mollusks these shells constituting the major fossil remains found in loess sequences the earlier studies mostly involved identifying species and determining biozones or assemblages with regard to the presence or absence of key species using the classic concept of biozones although this provided accurate elements with which to define an indicative biostratigraphy the time resolution was not always sufficiently precise to connect those studies with the more recent and high resolution analyses that are now routine in quaternary investigations this paper reviews mollusk studies carried out in northern hemisphere loess sequences and shows that a consideration of them as both biostratigraphic and palaeoclimatic indices enhances their potential and opens up particularly interesting areas of research the first example demonstrates that the last glacial mollusk assemblages in north america show compositional similarities to those in europe the climatic interpretation however appears more restricted by local conditions the second example shows that climatic conditions can be used to infer variations in the composition of biozones and thus address the significance of the distributional pattern of key species the third example demonstrates the value of high resolution studies and the potential of comparing the results of mollusk analyses with other proxies as an underpinning of the biological interpretation finally the need for more high resolution investigations in both north america and asia is stressed

kinematics of ductile shearing from outcrop to crustal scale in the monte rosa nappe western alps significant ductile deformation has produced widespread mylonitic structures in the basement orthogneisses and the mesozoic cover quartzites and marbles of the monte rosa nappe in the inner part of the western alps we summarize here the results of a detailed microstructural study at several scales of observation in the northern part of the nappe and discuss the kinematic significance and compatibility of such results most of the observed deformations can be accounted for by progressive wnw vergent shearing during and after the late eocene within a ductile shear zone of crustal scale the displacement of the hanging wall may have been in excess of several tens of kilometers however some ese vergent shear criteria cannot be reconciled with this general picture and suggest that local backthrusting occurred later near the toe of the monte rosa nappe

constrictional strain in a non coaxial shear zone implications for fold and rock fabric development central mojave metamorphic core complex california finite strain and fold analyses of footwall mylonites in the central mojave metamorphic core complex cmmcc reveal two distinct deformation paths that generated non coaxial constrictional strain the first path recorded in the waterman hills accomplishes constrictional strain through the formation of l tectonites at the grain scale the second path recorded in the mitchel range involves a combination of plane strain at the grain scale and y axis shortening through syn mylonitic folding the ductile shear zone in the waterman hills is approximately 500 m thick and is developed entirely within a miocene syn kinematic granodiorite strain magnitude decreases structurally downward the mylonites contain abundant ne directed non coaxial microstructures yet are l tectonites rf o analysis of quartz ribbon grain shapes indicate prolate strains k 6 and bulk chemical data suggest that mylonitization was isochemical or involved volume loss therefore ductile shearing in the waterman hills involved true constrictional strain at the grain scale immediately to the southeast in the mitchel range the lateral continuation of the shear zone is more than 1000 m thick and primarily involves lithologically heterogeneous pre tertiary basement the mylonitic fabric comprises a well developed foliation and ne trending stretching lineation rf o strain analysis was applied to grain shapes of cataclasized and strongly altered garnet porphyroclasts in a peraluminous granite in contrast to the waterman hills finite strains in these l s tectonites approximate plane strain k 1 1 however the mylonitic fabric is strongly folded about axes uniformly oriented subparallel to the stretching lineation the coaxial folds range from open to isoclinal we interpret the folds to have nucleated with axes parallel to the stretching lineation during mylonitization and to have accomplished y axis shortening in the shear zone macroscopic folds of the brittle detachment spatially correspond to open folds in the ductile shear zone suggesting that y axis shortening continued after the fault zone had reached the brittle regime corrugations and folds oriented subparallel to the transport direction are characteristic features of fault zones in cordilleran metamorphic core complexes therefore constrictional strain may be common in core complexes strain compatibility with upper plate rocks in core complexes may be maintained by y axis shortening along conjugate strike slip faults a nearly uniaxial stress field 3 2 1 is consistent with most of the structures formed in basin and range extension and could generate the observed constrictional strain

magma migration folding and disaggregation of migmatites in the karakoram shear zone ladakh nw india effi cient extraction of granitic magma from crustal sources requires the development of an extensive permeable network of melt bearing channels during deformation we investigate rocks that have undergone deformation and melting within the karakoram shear zone of ladakh nw india in which leucosome distribution is inferred to record the permeable network for magma extraction delicate structures preserved in these rocks record the development of this permeable magma network and its subsequent destruction to form a mobile mass of melt and solids resulting from the interplay between folding and magma migration during folding magma migrated from rock pores into layer parallel and axial planar sheets forming a stromatic migmatite or metatexite with two communicating sets of sheets intersecting parallel to the fold axis once the network was developed folding and stretching was eased by magma migration and slip along axial planar magma sheets folding and magma migration led to layer disaggregation transposition and the formation of a diatexite where rock coherency and banding were destroyed a number of structures developed during this process such as cuspate fold hinges disharmonic folds truncated layering shear along axial planar leucosomes and fl ow drag and disruption of melanosomes in this system magma migration was an integral part of deformation and assisted the folding and stretching of metatexites while folding gave rise to a magma sheet network now preserved as leucosomes as well as the pressure gradients that drove magma migration and the breakup of the metatexite thus metatexite folding increased melt interconnectivity while magma mobility increased strain rate and released differential stresses

large scale transposition by folding in northern norway a spectacular example of transposition in the sense ofsander 1911 is described from a large 2 3 km2 area of continuous outcrop in northern norway three generations of folds transpose an earlier layering into its persent orientation it is shown that the volume problems associated with isoclinal folding are largely accommodated by disharmony of the folds the large scale structure is considered and its relationship to regional structure is discussed

the significance of microgranitoid enclave shapes and orientations abstract enclaves are often incorrectly used to measure magmatic strains in plutons we emphasize that microgranitoid enclaves are not like other ellipsoidal markers used to determine strain for the following reasons 1 adjacent enclaves may form at different times and different places and initially have non spherical shapes with axial ratios up to 2 7 2 the final shapes and orientations of enclaves are a complex function of a initial shape and temperature of enclaves b subtle changes in composition melt percents volatiles grain sizes and thus temporally variable viscosity contrasts between the enclave and magma c a competition between strain and interfacial energies and d deformation path which may include internal strain and rigid rotations caused by magma flow during ascent convection expansion chamber boundary processes and tectonism 3 enclaves spend much of their time in magma as relatively rigid objects and thus rigidly rotate and potentially break apart rather than strain at matrix strain rates 4 in some instances enclaves do not record or track finite strain because of the above final enclave populations are heterogeneous and the use of single enclaves or enclave populations as strain markers violates many assumptions needed to complete strain analyses on the other hand a comparison of the preserved characteristics of igneous layering mineral fabrics and carefully evaluated enclave fabrics including internal mineral alignment in enclaves may provide qualitative data on the changing magnitude and kinematics of magmatic strains

european middle pleistocene loess chronostratigraphy some considerations based on evidence from the wels site austria a combination of site logging luminescence dating and comparison with different long and continuous records of past environmental conditions is used to elaborate an age model for the wels loess palaeosol site austria according to this model marine isotope stage mis 7 is reflected in the development of three red forest soils luvisols at this particular site this is contrary to previous assumptions that suggested the development of such soils in the region at 100 ka cyclicity if these results are correct this may question some previous conclusions regarding the general loess stratigraphy in many parts of europe

viscous collision in channel explains double domes in metamorphic core complexes in hot orogens gneiss domes are a response to upper crustal stretching and lower crustal flow two dimensional thermal mechanical modeling shows that localization of extension in the upper crust triggers in the deep crust oppositely verging horizontal flows that converge beneath the extended region upon viscous collision both flowing regions rotate upward to form two upright domes of foliation double domes separated by a steep median high strain zone in such systems horizontal shortening in the infrastructure develops in an overall extensional setting dome material follows a complex depth dependent strain history from shearing in the deep crustal channel to contraction upon viscous collision in the median high strain zone to extension upon advection into the shallow crust this depth dependent strain history is likely a general feature of dome evolution and is arguably well preserved in double domes such as the montagne noire france and naxos greece gneiss domes