comparison of radiocarbon dating of buried paleosols using arbuscular mycorrhizae spores and bulk soil samples ten paleosols from four separate soil pits located in karkevagge a glaciated trough in swedish lapland were dated using radiocarbon each soil was dated using both conventional bulk soil organic material som and a pure sample of arbuscular mycorrhizae am fungal spores the latter are produced by ubiquitous mycorrhizal fungi associated with the roots of many plant genera and may be viewed as a fossil material that has not interacted with any soil constituent subsequent to its emplacement in the soil at a time presumed to mark the cessation of a favorable soil forming environment regional deglaciation is presumed to have been about 10 000 bp while a cosmogenic exposure date obtained from the valley floor in karkevagge dated at 13 100 1638 bp the youngest paleosol buried at similar to 6 cm in soil pit m3 produced a spore date of 0 281 cal yr bp 1 sigma however bulk som dates of the same paleosol a horizon gave widely divergent dates and varied with the sample pretreatment ie the combustion temperature and the acid base treatment for example the bulk som dates for that paleosol ranged from a post bomb date of 0 314 cal yr bp 1 sigma to 2366 2710 cal yr bp 1 sigma when subjected to different pretreatments acid only acid base acid and the ignition temperatures 400 800 or 900 degrees c the oldest paleosol in the set buried at similar to 61 cm in soil pit m6 dated at 5479 5698 cal yr bp 1 sigma using spores but beyond calibration using bulk som the spore dates were all within the range to be expected of postglacial paleosols but the bulk som dates were frequently beyond the generally accepted time of deglaciation in addition all of the spore dates followed a conventional age depth pattern while the bulk som dates did not there are known possible sources of geogenic carbon contamination in karkevagge which may well account for the obviously invalid older bulk som dates an additional complication is that the spore dates vary somewhat with their density and diameter however where other types of fossil or charcoal are unavailable it appears that the enormously broad distribution of spores and their lack of interaction within the soil and persistence may well offer the prospect of an unusually useful radiocarbon dating medium within paleosols

late vistulian and holocene development of litho morpho pedogenic processes in the southern baltic coastal zone a case study from debina northern poland abstract the study aimed to reconstruct major phases of the litho morpho pedogenic processes in the southern baltic coastal zone near debina in northern poland five profiles of fossil soils in the coastal cliff were described sampled and analysed using standard procedures the studied outcrop covers a sequence of deposits including the basal till of the wiecie stadial mis 4 of the vistula glaciation the ablation till of the pomeranian phase mis 2 of the vistula glaciation the thin cover of glacilimnic sand the lacustrine sediments filling the palaeolake basin and aeolian deposits of varied age a sequence of paleosols developed successively within these deposits during the late vistulian and holocene mis 1 the initialization of soil forming processes occurred under the influence of periglacial environment and pioneer tundra vegetation endostagnic podzols abruptic epiarenic endoloamic endodensic developed within the plateau and they have some features typical for periglacial environments e g the presence of a cryoilluvial horizon the poor humification of soil organic matter the low abundance in n and p and the vertical displacement of p the basin of a small lake has been filled successively with sediments and dystric endocalcaric katostagnic fluvisols arenic humic endolimnic developed from these sediments during the late vistulian and early holocene the previously mentioned soils were buried by sandy cover in the early subatlantic due to intensification of aeolian processes ortsteinic podzols pantoarenic developed within a newly formed sandy cover a fossil fireplace preserved in the top of these soils constitutes evidence of human activity dating back almost 2000 years ortsteinic podzol pantoarenic are dissected by a dry valley that developed as a result of some fluvial episode perhaps induced by human activity it was subsequently filled with aeolian sands and dystric arenosols aeolic ochric developed within them ortsteinic podzol pantoarenic and dystric arenosols aeolic ochric were buried approximately five centuries ago our findings for the studied cliff section correlate well with results of other authors concerning the postglacial dynamics of morphogenetic processes the studies provide significantly enriched geomorphological knowledge related to the formation of relief in the study area with pedological aspects

processes dominating macro fabric generation in periglacial colluvium abstract mass wasting processes in a periglacial environment are considered to result from a combination of frost creep and gelifluction the relative importance of these processes is often difficult to determine but appears to be related to factors such as slope angle soil moisture content soil texture and vegetation cover further the importance of any one of these factors can vary from year to year thereby making long term predictions of slope stability or reconstructions of behaviour history difficult this study uses two dimensional macro fabric analysis as a recorder of the dominant mode of mass wasting on a slope clast trend and plunge data were collected from 68 sites at eagle summit alaska and examined in two separate dimensions the plane of the slope to represent the stress field driven by gravity and in a vertical plane trending down the slope to represent the stress field created by frost heaving pressures circular correlation tests indicate the importance of the downslope stress field on clast position in the plane of the slope in the vertical plane clast plunge varies according to slope on gentle slopes clasts tend to be steeply dipping on moderate slopes they are parallel to the plane of the slope and on steep slopes they are imbricated these observations correspond to modeled experiments of slope deformation under periglacial conditions and suggest that at the scale of the slope mass wasting processes are influenced by varying intensities of frost heave and gravity transfer that are conditioned by slope angle

the three dimensional geometry of simulated porphyroblast inclusion trails inert marker viscous flow models a fluid dynamic model for a rigid spherical porphyroblast growing in a viscous fluid matrix undergoing simple shear deformation predicts an arrangement of captured inert inclusions that is remarkably similar to the spiral pattern observed in synkinematic rolled garnets the model assumes only creeping stokes flow of the matrix and a kinetic model for the growth of the porphyroblast of the form rm km where r is the crystal radius is the amount of shear induced rotation and m and k are kinetic parameters for rotation less than 18d j b thompson and j l rosenfeld s simple ring model provides a surprisingly accurate description of the three dimensional geometry of the central inclusion surface in the simulated porphyroblasts although marker planes originally parallel to the shear plane are deflected around the porphyroblast their intersections with its surface remain approximately circular for much larger amounts of rotation than anticipated by rosenfeld the polar coordinate equation t r of the double spiral formed by the trace of the central inclusion surface in a section through the centre of simulated porphyroblasts is also surprisingly simple as follows rm 6 5k m this relationship was observed over the complete range of rotation angles investigated 0 720d and could form a reasonable basis for estimating the growth rotation history of rolled garnets from the shape of their spiral inclusion trails two dimensional sections through the simulated porphyroblasts parallel to the rotation axis yield clamshell rosenfeld s term inclusion geometries similar to the controversial millipede patterns observed in many natural porphyroblasts

deformation partitioning shear zone development and the role of undeformable objects abstract the formation of a mylonite zone by homogeneous progressive simple shear is highly unlikely because heterogeneous strain of grains with different compositions causes deformation partitioning and results in progressive inhomogeneous simple shear or non coaxial progressive bulk inhomogeneous shortening however the presence of rigid bodies in a zone of rock undergoing bulk simple shear spreads and homogenizes the stress field such that the instantaneous displacement field is essentially homogeneous at a scale up to at least four times the diameter of the rigid object that is the portion of rock surrounding the rigid body deforms by homogeneous progressive simple shear and the rigid object is forced to rotate this has considerable implications for the rotation or lack thereof of unstrained porphyroclasts and porphyroblasts and hence the information such grains preserve about the sense of shear on their margins or through inclusion trails geometric relationships between porphyroclasts or porphyroblasts and the surrounding matrix that are superficially similar can indicate exactly the opposite sense of shear depending on whether the porphyroclasts or porphyroblasts have or have not rotated leading to considerable problems in interpretation of the bulk movement in a shear zone resolution of these relationships enables ready distinction of whether the deformation history involved progressive bulk inhomogeneous shortening or progressive simple shear in particular these results have considerable implications for the origin of blueschist minerals preserved in garnet porphyroblasts via the roles of strain softening and hardening during mylonitization due to the destruction of feldspar porphyroclasts and growth of garnet porphyroblasts respectively

climate environment and stratigraphy of the last pleistocene glacial stage in poland abstract the aim of the paper is to present general characteristics of the climate in poland during the vistulian weichselian expressed by changes of its continentality during warm and cold intervals this last glacial stage in poland is commonly subdivided into early vistulian mis 5d a lower plenivistulian mis 4 interplenivistulian mis 3 and upper plenivistulian and late vistulian mis 2 main climatic features of this glacial stage could be reconstructed based on compilation from published data concerning characteristics of glacial fluvial and aeolian sedimentary environments geomorphology analysis of indicator plant species coleoptera and geographical distribution of periglacial structures these data were indicative especially for evaluation of mean temperature of the warmest and the coldest months but could be also helpful in determination of drier intervals and some aspects of general atmospheric circulation paleoclimatic characteristics of the last glacial stage from the territory of poland were put into the european context during the early vistulian in eastern poland higher continentality was characteristic for interstadials amersfoort brorup and odderade and was considerably lower during the intervening colder stadials herning a cooling between amersfoort and brorup rederstall among the interstadials the most continental climate occurred during brorup similar continentality as at present considerably less during amersfoort and the least during odderade a decreasing trend of continentality for the cold stadials of the early weichselian eastwards in europe could result from a remarkably less dynamic gulf stream in the north atlantic when the ocean was covered with vast sea ice during winters whereas the adjoining continent was occupied by permafrost and the atmospheric circulation was presumably driven also by the scandinavian ice sheet

microscopic and microchemical study of iron sulphide weathering in a chronosequence of technogenic and natural soils abstract sulphide alterations are among the most important mineralogical aspects of the functioning of soils developed from sulphide bearing parent materials in the present study the processes of iron sulphide weathering were investigated in a system including sulphide crystals and secondary minerals adjacent to oxidised sulphides light microscope observations and scanning electron microscope energy dispersive spectrometry sem eds analyses were used in order to examine evidences of iron sulphide decay at a microscopic and submicroscopic scales as well as to determine the modes and effects of sulphide weathering on an example of a chronosequence of technogenic soils technosols and naturally developed soils leptosols and cambisols in poland the study covered 1 several years old technosols developed on the dump of the abandoned hard coal mine in trzebinia town 2 several dozen of years old technosols developed on mine spoils of the abandoned pyrite mine in rudki village 3 100 200 years old technosols developed on dumps of the abandoned pyrite mine in wie ciszowice village as well as 4 leptosols and cambisols developed on natural outcrops of pyrite bearing schists in the vicinity of the mine in wie ciszowice chemical weathering was the most important process involved in the alteration of iron sulphides in the soils studied the process is expressed by 1 the oxidation of sulphides resulting in a subsequent crystallisation of iron oxides and sulphates from fe and sulphate ions released to the soil solution as well as by 2 the development of pseudomorphs after sulphides due to the gradual in situ transformation of sulphides into secondary minerals iron oxides mainly porous poorly crystalline iron oxides predominated across the products of iron sulphide oxidation in young technogenic soils from rudki in contrast to old technogenic and natural soils from wie ciszowice where massive well crystallised iron oxides prevailed this suggests that the degree of crystallinity of iron oxides increases along with the age of soils microstratification was a typical feature of secondary iron oxides occurring in old soils from wie ciszowice the eds analyses performed along the lines perpendicular to stratified oxides showed that the alternating microlayers differed from each other in terms of contents of oxygen o poor layers were alternated with layers rich in this element this suggests that temporal changes of oxygen concentration in soils may affect the process of iron sulphide transformation the content of most trace elements including heavy metals such as cu zn and pb in the examined iron sulphides analysed by eds was low furthermore amounts of these elements in secondary oxide rims were reported to be slightly elevated in comparison with the adjacent sulphides this suggests that the rims did not constitute places of concentration of high amounts of trace elements in the soils investigated

growth and deformation of porphyroblasts in the foothills terrane central sierra nevada california negotiating a microstructural minefield the main porphyroblastic minerals in schists and phyllites of the foothills terrane western metamorphic belt central sierra nevada california are cordierite and andalusite mostly chiastolite less commonly biotite muscovite chlorite garnet or staurolite are also present as porphyroblasts the variety of porphyroblast and matrix microstructures in these rocks makes them suitable for testing three modern hypotheses on growth and deformation of porphyroblasts 1 porphyroblast growth is always syndeformational 2 porphyroblasts nucleate only in low strain largely coaxially deformed quartz rich q domains of a crenulation foliation and are dissolved in active high strain non coaxially deformed mica rich m domains the spacing between which limits the size of the porphyroblasts and 3 porphyroblasts generally do not rotate with respect to geographical coordinates during deformation provided they do not deform internally so that they may be used as reliable indicators of the orientation of former regional structural surfaces even on the scale of orogenic belts some porphyroblast matrix relationships in the foothills terrane are inconsistent with hypotheses 1 and 2 and others are equivocal for example in many rocks it cannot be determined whether the porphyroblasts grew where the strain had already been partitioned into m and q domains whether the porphyroblasts caused this partitioning or both although most porphyroblasts appear to be syndeformational as predicted by hypothesis 1 observations that do not support the general application of hypotheses 1 and 2 to rocks of the foothills terrane include a lack of residual crenulations in many strain shadows and alternative explanations where they are present b absence of porphyroblasts smaller than the distance between nearest mica rich domains c nucleation of crenulations on existing porphyroblasts rather than nucleation of porphyroblasts between existing crenulations d presence of micaceous arcs in an undifferentiated matrix against some porphyroblasts suggesting static growth e absence of crenulations in porphyroblastic rocks showing sedimentary bedding and f porphyroblasts with very small random inclusions which are probably pre deformational similarly porphyroblasts that have overgrown sets of crenulations and porphyroblasts with micaceous arcs are probably post deformational at least on the scale of a large thin section and probably over much larger areas judging from mesoscopic structural evidence some porphyroblasts in rocks of the foothills terrane do not appear to have rotated with respect to geographical coordinates during matrix deformation in accordance with hypothesis 3 at least on the scale of a large thin section however other porphyroblasts evidently have rotated in some instances this appears to be due to mutual interference but many apparently rotational porphyroblasts are too far apart to have interfered with each other which indicates that the rotation was associated with deformation of the matrix the occurrence of planar bedding surfaces adjacent to porphyroblasts about which bedding and or foliation surfaces are folded suggests rotation of the porphyroblasts during non coaxial flow parallel to bedding rather than crenulation of the matrix foliation around static porphyroblasts it appears that porphyroblasts may rotate during deformation if the matrix is relatively homogeneous so that the strain is effectively non coaxial this may occur after homogenization of a matrix in response to the strongest degree of crenulation folding whereas the same porphyroblasts may have been inhibited from rotating previously when strain accumulation was partitioned in the matrix

deformation partitioning and porphyroblast rotation in meta morphic rocks a radical reinterpretation abstract most porphyroblasts never rotate during ductile deformation provided they do not intern ally deform during subsequent events with the exception of relatively uncommon but spectacular examples of spiralling garnets instead the sur rounding foliation rotates and reactivates due to partitioning of the deformation around the porphyroblast consequently porphyroblasts commonly preserve the orientation of early foliations and stretching lineations within strain shadows or inclusion trails even where these structures have been rotated or obliterated in the matrix due to subsequent deformation these relationships can be readily used to help develop an understanding of the processes of foliation development and they demonstrate the prominent role of reactivation of old foliations during subse quent deformation they can also be used to determine the deformation history as porphyro blasts only rotate when the deformation cannot partition and involves progressive shearing with no combined bulk shortening component

rolling structures at large shear strain abstract at large shear strain shear criteria are often obliterated or become ambiguous from examination of both natural examples and experimental models we describe a new criterion called rolling structure widely represented in sheared rocks a typical rolling structure is composed of a rigid or competent object e g porphyroclast boudin fossil etc with two tails asymmetrically disposed around it in most cases tails are of the same material as that of the rotating object and result from strain softening and grain size reduction at the object periphery forming a mantle z and s asymmetries of rolling structures represent dextral and sinistral senses of shearing respectively tails must not be confused with pressure shadows which usually present an opposite asymmetry for a given shear sense besides the determination of the sense of shear the occurrence of these structures allows a minimum estimate of the strain intensity in strongly sheared rocks since rolling structure length is proportional to shear strain

early holocene forest fires drift sands and usselo type paleosols in the laarder wasmeren area near hilversum the netherlands implications for the history of sand landscapes and the potential role of mesolithic land use abstract in the laarder wasmeren area in the western netherlands late pleistocene cover sands and overlying early holocene drift sands show various paleosols which can be characterized as more or less incipient podzols we dated those soils and sands by radiocarbon analysis and osl and we used biostratigraphical dating based on the known chronology of the vegetation history apart from usselo soils of allerod age we found early holocene soils showing usselo soil characteristics but with relatively advanced podzolisation covered by early holocene early middle holocene drift sands we discuss their age and origin and reflect on the role of fires and ecosystem degradation in the early development of heathland podzols and drift sands in the netherlands prior to any neolithic farming we hypothesize about the possible role of mesolithic man stimulating habitats for corylus avellana by burning pine forest in the longer term inducing the observed ecosystem degradation transformation of forest into open short vegetation acidification and concurrent podzolisation wind erosion this hypothesis is in line with studies in adjacent nw european countries which are reviewed and an alternative for the theory of vera 2000 who assumed that open forests and short vegetation resulted from grazing pressure by large herbivores

aureole deformation by flattening around a diapir during in situ ballooning the cannibal creek granite the cannibal creek granite a foliated pluton within a strongly deformed aureole shows several diagnostic features of a diapir the intensity of the aureole deformation diminished away from the contact the aureole foliation is continuous with that of the granite and forms closed elliptical trend lines and the contact metamorphic minerals are synkinematic with regard to the aureole foliation the pluton deformed its aureole in three stages involving initially brittle then ductile and finally brittle deformation styles initial intrusion of a low strength magma stoped kinked and flexed aside its overburden crystallization of the magma prevented further rise and it ballooned and deformed its aureole evidently entirely by ductile bulk shortening perpendicular to the contact this the major stage of aureole deformation records no evidence of vertical movement of the pluton or of progressive simple shear along its margin during this stage the magma may have been theologically a high strength bing

porphyroblast inclusion trails the key to orogenesis detailed microstructural analysis of inclusion trails in hundreds of garnet porphyroblasts from rocks where spiral shaped inclusion trails are common indicates that spiral shaped trails did not form by rotation of the growing porphyroblasts relative to geographic coordinates they formed instead by progressive growth by porphyroblasts over several sets of near orthogonal foliations that successively overprint one another the orientations of these near orthogonal foliations are alternately near vertical and near horizontal in all porphyroblasts examined this provides very strong evidence for lack of porphyroblast rotation the deformation path recorded by these porphyroblasts indicates that the process of orogenesis involves a multiply repeated two stage cycle of 1 crustal shortening and thickening with the development of a near vertical foliation with a steep stretching lineation followed by 2 gravitational instability and collapse of this uplifted pile with the development of a near horizontal foliation gravitational spreading near coaxial vertical shortening and consequent thrusting on the orogen margins correlation of inclusion trail overprinting relationships and asymmetry in porphyroblasts with foliation overprinting relationships observed in the field allows determination of where the rocks studied lie and have moved within an orogen this information combined with information about chemical zoning in porphyroblasts provides details about the structural metamorphic p t t paths the rocks have followed the ductile deformation environment in which a porphyroblast can rotate relative to geographic coordinates during orogenesis is spatially restricted in continental crust to vertical ductile tear transcurrent faults across which there is no component of bulk shortening or transpression

de bugging the millipede porphyroblast microstructure a serial thin section study and 3 d computer animation abstract seventy five spatially orientated serial thin sections cut from a single rock containing millipede porphy roblast microstructure from the robertson river metamorphics australia reveal thc three dimensional 3 dj geometry of oppositely concave microfolds ocms that define the microstructurc electronic animations showing progressive scrial sections of thc 3 d microstructurc arc made available via the world wide web the ocm amplitudes decrease regularly from a maximum in near central sections to a minimum in near marginal scctions whereas the ocm interlimb angles increase regularly from a minimum in near ccntral sections to a maximum in near marginal sections these observations illustrate that the ocms are noncylindrical surfaces with culminations located in near central scctions because the porphyroblast cores appear to have been present before significant development of the syn ocm foliation all of the ocms were formed by heterogcncous cxtension around thcse cores the overall gcometry of the ocms described hcre reflects the strain state and cannot be used to constrain defor mation paths

porphyroblast nucleation growth and dissolution in regional metamorphic rocks as a function of deformation partitioning during foliation development in regional metamorphic rocks the partitioning of deformation into progressive shearing and progressive shortening components results in strain and strain rate gradients across the boundaries between the partitioned zones these generate dislocation density gradients and hence chemical potential gradients that drive dissolution and solution transfer phyllosilicates and graphite are well adapted to accommodating progressive shearing without necessarily building up large dislocation density gradients within a grain because of their uniquely layered crystal structure however most silicates and oxides cannot accommodate strain transitions within grains without associated dislocation density gradients and hence are susceptible to dissolution and solution transfer as a consequence zones of progressive shearing become zones of dissolution of most minerals and of concentration of phyllosilicates and graphite exceptions are mylonites where strain rates are commonly high enough for plastic deformation to dominate over diffusion rates and therefore over dissolution and solution transfer porphyroblastic minerals cannot nucleate and grow in zones of active progressive shearing as they would be dissolved by the effects of shearing strain on their boundaries however they can nucleate and grow in zones of progressive shortening and this is aided by the propensity for microfracturing in these zones which allows rapid access of fluids carrying the material presumed to be necessary for nucleation and growth zones of progessive shortening also have a number of characteristics that help to lower the activation energy barrier for nucleation this includes a build up of stored strain energy relative to zones of progressive shearing in which dissolution is occuring porphyroblast growth is generally syndeformational and previously accepted criteria for static growth are not valid when the role of deformation partitioning is taken into account porphyroblasts in a contact aureole do not grow statically either as microfracturing associated with emplacement allows access of fluids in a fashion that is similar to microfracturing in zones of progressive shortening the criteria used for porphyroblast timing can be readily accommodated in terms of deformation partitioning reactivation of deforming foliations and a general lack of rotation of porphyroblasts with the spectacular exception of genuinely spiralling garnet porphyroblasts

ductile thrusting in the himalayas shear sense criteria and stretching lineations the most useful criteria used for the determination of the sense of shear can be found in the huge himalayan ductile shear zone known as m c t they allow the determination of the sense of shear in relation with an unequivocal southward directed intracontinental thrust the various criteria analyzed at different scales of observation show the permanence of the shear flow regime throughout the metamorphic evolution however most of the observed shear criteria are due to late nappe emplacement postdating the climax of the metamorphism the most striking feature is the stretching lineation which is roughly normal to the thrust trace all along the belt it parallels everywhere the shear direction and thus indicates the transport direction of the nappes the observed radial pattern of stretch trajectories implies that the local motion does not correspond to the average plate convergence

rotational quantities in homogeneous flow and the development of smallscale structure abstract a summary discussion is given of attempts to quantify the degree of non coaxiality of rock flow from observations of rock structure and of some principles governing the sensitivity of structure to non coaxiality this is preceded by an extended review of relevant terminology since some of the current confusion about rotational features in rocks stems from confusion about basic concepts and terminology from continuum mechanics the kinematic vorticity number has been estimated for naturally deformed rocks from three localities these yield vorticity numbers ranging from 0 35 to 0 9 corresponding to flows intermediate in character between pure and simple shearing

porphyroblast non rotation during crustal extension in the variscan lys caillaouas massif pyrenees abstract the dominant foliation s 2 in the variscan lys caillaouas massif central pyrenees france spain formed in a subvertical orientation during crustal thickening d 2 subsequent non coaxial crustal extension produced a subhorizontal crenulation cleavage s 3 whereby s 2 was folded and rotated andalusite staurolite cordierite and biotite porphyroblasts grew very early during this extension d 3 and included s 2 as straight curved and weakly crenulated inclusion trails these inclusion trails exhibit a strong subvertical preferred orientation which is independent of the local magnitude of d 3 strain the dip angle of the external main foliation s 2 or the aspect ratio and shape orientation of porphyroblasts this indicates that porphyroblasts did not rotate in the d 3 deformation field and hence preserve the orientation of s 2 at the time it was trapped in the porphyroblast relative to the bulk d 3 flow plane porphyroblasts could maintain a stable orientation in the d 3 flow due to complete accommodation of the bulk flow vorticity by heterogeneous shear strain the lack of vorticity of local volumes of zero shear strain such as porphyroblasts was balanced by concentration of shear strain in planar zones anastomosing around them it is likely that s 2 maintained a subhorizontal orientation throughout the d 3 crustal extension which would imply that porphyroblasts also remained stationary relative to the earth s surface during d 3 whereas s 2 in the deforming matrix experienced shear induced rotation a late brittle ductile folding event d 4 involving differential rigid block rotations dispersed the orientation of inclusion trails to some degree these late rotations could be corrected for by artificial unfolding of the f 4 folds

the kinematic interpretation of obliquely transected porphyroblasts an example from the trois seigneurs massif france abstract obliquely transected porphyroblasts otps contain a straight inclusion pattern that is continuous with the external foliation but oblique in orientation otps are interpreted to form by porphyroblast growth between two phases of deformation the obliqueness of the inclusion pattern and external foliation is due to the second deformation phase and has been variously explained by porphyroblast rotation in the kinematic reference frame of bulk flow or by foliation rotation around a stationary porphyroblast the two models imply opposite sense of vorticity also loosely referred to as sense of shear to produce the same geometry and their relevance should be known if otps are to be used as sense of vorticity indicators andalusite otps in the trois seigneurs massif french pyrenees have a spool shape in three dimensions that is interpreted to result from passive overgrowth of andalusite on a spaced s 2 cleavage subsequent non coaxial d 3 flow led to development of an s 3 crenulation cleavage and the otp geometry although the porphyroblasts rotated rotation of the foliation in the kinematic reference frame of bulk flow was mainly responsible for the otp geometry this example shows that otps can indeed develop by foliation rotation in non coaxial flow similar looking otps can apparently develop in flows with opposite sense of vorticity depending on whether foliation or porphyroblast rotation is dominant the dominance of either development mechanism depends on the importance of flow partitioning and solution transfer during progressive deformation

a chronogram for postglacial soil landscape change from the palliser triangle canada the soil landscape chronogram summarizes the ways in which five slope wash erosion cycles followed by two aeolian cycles interrupted postglacial soil formation in an enclosed hillslope system from hummocky moraine terrain the four slope wash cycles that followed the early postglacial cycle occurred between 7 7 and 3 ka bp and caused about half of the total postglacial relief reduction at the onset of the latter cycles the locus of erosion switched from its prevalent position on the lower slope to the upper backslope indicating recurrent fundamental changes in slope hydrology the ensuing stratigraphic framework has a downslope thickening and fining clastic wedge grading into the bottomland sequence and subdivided by soil catenas that merge upslope into a single compound mantle on the upland the aeolian cycles entailed localized loess dispersal systems producing minor mantles of sandy loam loess with saltation load deposits on the leeward slope and suspension load deposits elsewhere accumulation of long range calcareous dust during the loess cycles supplied most of the secondary carbonates found in the buried soils three radiocarbon dates together with mazama tephra enable partial correlation of these events to the regional holocene climate record

periglacial cover beds on the swiss plateau indicators of soil climate and landscape evolution during the late quaternary abstract soils and the stratification of their parent materials were studied on the central swiss plateau this area is characterized by glacial deposits varying from late glacial to pre wurmian in age soils of all studied sites are developed within colluvial layers the so called cover beds in relation to the underlying deposits we find a regular spatial distribution of cover bed types a surficial layer upper layer with relatively constant thickness around 50 cm independent of relief position covers pleistocene sediments of any age therefore it was formed mainly by cryoturbation solifluction after the final glacier retreat from the swiss plateau younger dryas or oldest dryas age layers that originate mainly from aeolian processes intermediate layers are restricted to areas outside the recessional moraines of the berne stade bs hence they were formed merely up to the late pleniglacial they frequently consist of two distinct layers outside the glaciation of the last glacial maximum lgm cover beds in places overlie pre lgm palaeosol relics probably of eemian age or even older these are preserved even on higher relief positions indicating that periglacial erosion during the pleniglacial was only marginal the palaeosol relics also occur on till of the so called older wangen stade which is commonly believed to represent the lgm whereas we consider it to be older at least partly eventually the distribution of soil types and their ecological characteristics are influenced considerably by cover beds as these beds reflect distinct phases of the pleistocene colluvial sediments provide a major tool for linking modern landscape characteristics to the late quaternary climate evolution

two dimensional refold interference patterns abstract when a rock undergoes two generations of folding complex three dimensional refolded structures result if such a structure is then sectioned two dimensional interference patterns result these patterns have been discussed before but the incredible variety and complexities of these patterns can be shown only with a large number of diagrams using a computer simulation various refolded structures have been sliced at every unique 30 combination of strike and dip thirty sections per structure the characteristics of the patterns observed are discussed and recurring recognizable patterns are identified

arctic soil properties associated with micro relief forms in the bellsund region spitsbergen abstract the following patterning of the ground surface was observed in the bellsund region sorted circles mud boils cell forms solifluction striped forms and large polygons tundra polygons the soils associated with these forms often have different morphological granulometric and chemical properties and plant covers tundra polygons and surfaces without relief are usually accompanied by relatively well developed brown soils with a dense plant cover 70 100 such forms occur mainly on loamy sands and loams with abundant 1 0 0 1 mm particles brown soils are rich in humus which decreases with depth typical gley soils usually with a sparse plant cover are associated with cell forms sorted circles and mud boils solifluctional forms are usually accompanied by gley like soils rarely by brown like ones gley and gley like soils occur on sediments rich in fractions

how useful are millipede and other similar porphyroblast microstructures for determining synmetamorphic deformation histories oppositely concave microfolds ocms in and adjacent to porphyroblasts can be classified into five nongenetic types type 1 ocms are found in sections through porphyroblasts with spiral shaped inclusion trails cut parallel to the spiral axes and commonly show closed foliation loops type 2 ocms commonly referred to as millipede microstructure are highly symmetrical the foliation folded into ocms being approximately perpendicular to the overprinting foliation type 3 ocms are similar to type 2 but are asymmetrical the foliation folded into ocms being variably oblique to the overprinting foliation type 4 ocms are highly asymmctrical only one foliation is present and this foliation is parallel to the local shear plane type 5 ocms result from porphyroblast growth over a microfold interference pattern types 1 and 2 are commonly interpreted as indicating highly noncoaxial and highly coaxial bulk deformation paths respectively during porphyroblast growth however theoretically they can form by any deformation path intermediate between bulk coaxial shortening and bulk simple shearing given particular initial foliation orientation and timing of porphyroblast growth type 3 ocms can also form during these intermcdiatc deformation paths and are commonly found in the same rocks as type 2 ocms type 4 ocms may indicate highly noncoaxial deformation during porphyroblast growth but may be difficult to distinguish from type 3 ocms thus types 1 3 and possibly 4 reflect the finite strain state giving no information about the rotational component of the deformation s responsible for their formation furthermore there is a lack of unequivocal independent evidence for the degree of noncoaxiality of deformation s during the growth of porphyroblasts containing ocms type 2 ocms that occur independently of porphyroblasts or other rigid objects might indicate highly coaxial bulk shortening but there is a lack of supporting physical or computer modelling it is possible that microstructures in the matrix around ocms formed during highly noncoaxial and highly coaxial deformation histories might have specific characteristics that allow them to be distinguished from one another however determining degrees of noncoaxiality from rock fabrics is a major long standing problem in structural geology

properties and soil development of late pleistocene paleosols from seward peninsula northwest alaska abstract soils on seward peninsula northwest alaska that were buried about 17 500 years ago and froze after burial present a unique opportunity to study soil development under the conditions of the last glacial maximum stratigraphic sections were excavated during the summers of 1993 and 1994 study sites were located on steep banks of thaw lakes we described soil morphology including cryogenic features and sampled for chemical and physical analyses all paleosols are permafrost soils that developed in calcareous loess and have roots present throughout colors are predominantly grayish and either reflect original loess color or periodic saturation of the soils possibly caused by the permafrost environment active layer thicknesses before burial ranged from 32 to 64 cm organic carbon contents average 3 0 carbon nitrogen ratios average 9 cation exchange capacities average 19 1 cmol kg and base saturations generally exceed 100 there is no evidence of leaching in the profile soil formation occurred simultaneously to the deposition of the parent material loess morphological and chemical data suggest that soil development was weak and confined to organic matter accumulation and hydrolysis of iron all studied soils show similar morphological chemical and physical properties which suggests a relatively uniform mode of soil formation in the study area soil forming conditions on northern seward peninsula during the last glacial maximum were severe and combined with fairly continuous loess deposition they resulted in weakly developed nutrient rich soils

microstructural analysis of the classical spiral garnet porphyroblasts of south east vermont evidence for non rotation new data strongly suggest that the classical spiral garnet porphyroblasts of south east vermont usa generally did not rotate relative to geographical coordinates throughout several stages of non coaxial ductile deformation the continuity of inclusion trails si in these porphyroblasts is commonly disrupted by planar to weakly arcuate discontinuities consisting of truncations and differentiation zones where quartz graphite si bend sharply into more graphitic si discontinuous tight microfold hinges with relatively straight axial planes are also present these microstructures form part of a complete morphological gradation between near orthogonally arranged discontinuous inclusion segments and smoothly curving continuous si spirals some 2700 pitch measurements of well developed inclusion discontinuities and discontinuous microfold axial planes were taken from several hundred vertically orientated thin sections of various strike from specimens collected at 28 different locations around the chester and athens domes the results indicate that the discontinuities have predominantly subvertical and subhorizontal orientations irrespective of variations in the external foliation attitude macrostructural geometry and apparent porphyroblast matrix rotation angles combined with evidence for textural zoning this supports the recent hypothesis that porphyroblasts grow incrementally during successive cycles of subvertical and subhorizontal crenulation cleavage development less common inclined discontinuities are interpreted as resulting from deflection of anastomosing matrix foliations around obliquely orientated crystal faces prior to inclusion most of the idioblastic garnet porphyroblasts have a preferred crystallographic orientation dimensionally elongate idioblasts also have a preferred shape orientation with long axes orientated normal to the mica folia within which epitaxial nucleation occurred truncations and differentiation zones result from the formation of differentiated crenulation cleavage seams against porphyroblast margins in association with progressive and selective strain induced dissolution of matrix minerals and locally also the porphyroblast margin non rotation of porphyroblasts relative to geographical coordinates suggests that deformation at the microscale is heterogeneous and discontinuous in the presence of undeformed relatively large and rigid heterogeneities which cause the progressive shearing rotational component of deformation to partition around them the spiral garnet porphyroblasts therefore preserve the most complete record of the complex polyphase tectonic and metamorphic history experienced in this area most of which was destroyed in the matrix by progressive foliation rotation and reactivation together with recrystallization

environmental changes of a shallow kettle lake catchment in a young glacial landscape sumowskie lake catchment north central poland abstract on the basis of detailed analysis sedimentological palynological macroremains geochemical and gis analysis the development of the sumowskie paleolake was reconstructed obtained results led to distinguish three main stages of the evolution of the basin and its catchment during the late glacial and the holocene the lacustrine stage the lake overgrowth stage and the post lacustrine stage study site is located in the western part of the brodnica lakeland north eastern poland within the former sumowskie lake bottom multidisciplinary research was conducted for two cores sedimentological palynological plant macroremains sum a 149 cm and sum c 51 cm and the soil profile sum 3 sedimentological geochemical gis analyses land cover and water level changes were carried out for the nowadays sumowskie lakes catchment it was confirmed that climate was the most important factor influencing the evolution of the lake and its surrounding although the role of this factor decreased in the neo holocene period in favor of rapidly growing human impact changes of the water level were much more abrupt and lasted longer e g 9500 5000 bp hiatus caused by the water level decrease than in other described basins of the region due to the specific geomorphologic situation shallow kettle basins could alternately act as lakes and wetlands as they are well spread in the young glacial area the strong influence of this abrupt and long term events should be reconsidered

sequential growth of cordierite and andalusite porphyroblasts cooma complex australia microstructural evidence of a prograde reaction low pressure prograde metamorphism of pelitic rocks in the cooma complex south east australia has produced cordierite andalusite schists at intermediate grades the first foliation s1 is preserved largely as inclusion trails in cordierite porphyroblasts microstructural evidence indicates that the cordierite porphyroblasts grew during the early stages of development of a crenulation foliation s2 and that andalusite porphyroblasts grew during the development of a later crenulation foliation s3 microstructural evidence also indicates that the andalusite was a product of the prograde reaction cordierite muscovite andalusite biotite quartz the occurrence of the products of this reaction in beard structures between cordierite microboudins formed by extension in s3 confirms that the andalusite grew during the development of s3 the investigation shows that porphyroblast matrix relationships can preserve the orientation of an early s surface that has been largely obliterated from the matrix as well as providing relatively direct evidence of sequential mineral growth and metamorphic reactions

the termination of the last major phase of aeolian sand movement coastal dunefields denmark optically stimulated luminescence osl dating of sand samples from stabilized or inactive coastal dunes in denmark provides information on the age of the termination phase of the last major aeolian activity period a total of 26 sand samples were taken from four different coastal dunefields around the north sea skagerrak and kattegat coasts of denmark the osl dates indicate that the last major phase of aeolian activity terminated between ad 1860 and 1905 most of the dunes examined in this study were active around 1820 during a period documented to have been very stormy a dune management scheme started around 1792 and this no doubt was a major cause of dunefield stabilization but an overall decline of storminess particularly spring and summer storminess around the end of the 19th century must also have contributed to the increasing inactivity of coastal dunes the new osl dates on aeolian sand movement agree well with historical data and data from topographic maps on dune movement this agreement supports the observation from earlier work that osl dating of recent aeolian sand movement is accurate over the last few decades to centuries copyright 2005 john wiley sons ltd

the record of hydroclimatic changes in the sediments of a kettle hole in a young glacial landscape north central poland abstract multidisciplinary research on the bottom sediments of a kettle hole at the retno site the brodnica lake district north central poland provided some information about changes in hydroclimatic conditions in the late glacial and the holocene detailed analysis sedimentological palynological macroremains geochemical and radiocarbon dating helped to identify 6 stages in the development of the depression in the village of gaj near retno lake with 11 phases of hydroclimatic conditions sediments of the retno profile with a total thickness of 6 72 m reflected individual natural stages in the development of the depression from a lake to a peat bog most of the environmental changes were gradual a sequence of late glacial and early holocene lacustrine sediments mainly gyttja occurred in the floor of the profile the upper 4 10 m consisted of paludal deposits peat of transitional and raised bogs divided at a depth of 1 56 1 54 m b g l by a thin layer of clay dated late subboreal early subatlantic the presence of this layer indicates a sudden change in the environmental conditions associated with a water level rise at that time denudation processes started within the drainage basin probably induced by human activity the important effects related to contemporary anthropopressure included desiccation of the peat bog muck formation in the uppermost 10 cm layer and elevated trophic conditions resulting in a change of the vegetation cover

late quaternary landscape development at the margin of the pomeranian phase mis 2 near lake wygonin northern poland abstract in central europe late quaternary landscapes experienced multiple phases of geomorphologic activity in this study we used a combined geomorphological pedological sedimentological and palynological approach to characterize landscape development after the last glacial maximum lgm near lake wygonin in northern poland the pedostratigraphical findings from soil pits and drillings were extrapolated using ground penetrating radar gpr and electric resistivity tomography ert during the pomeranian phase glacial and fluvioglacial processes dominated the landscape near lake wygonin at the end of the glacial period periglacial processes became relevant and caused the formation of ventifacts and coversands containing coated sand grains at approximately 15 290 14 800 cal yr bp a small pond formed in a kettle hole profile bwi 2 the lacustrine sediments lack eolian sand components and therefore indicate the decline of eolian processes during that time the increase of juniperus and rock rose helianthemum in the pollen diagram is a prominent marker of the younger dryas at the end of the younger dryas a partial reshaping of the landscape is indicated by abundant charcoal fragments in disturbed lake sediments no geomorphologic activity since the beginning of the holocene is documented in the terrestrial and wetland archives the anthropogenic impact is reflected in the pollen diagram by the occurrence of rye pollen grains secale cereale and translocated soil sediments dated to 1560 1410 cal yr bp proving agricultural use of the immediate vicinity with the onset of land use gully incision and the accumulation of colluvial fans reshaped the landscape locally since 540 460 cal yr bp further gully incision in the steep forest tracks has been associated with the intensification of forestry outside of the gully catchments the weakly podzolized rubic brunic arenosols show no features of holocene soil erosion

paleoenvironmental interpretation based on macro and microstructure analysis of pleistocene slope covers a case study from the miechow upland poland abstract the purpose of the research was to provide a paleoenvironmental reconstruction of the origin of periglacial slope covers in the miechow upland in southern poland the investigated site produced data for the analysis of loess fossil soils cryogenic structures as well as slope deposits complementary sedimentological and soil analyses served as the basis of the research in addition to macroscopic research micromorphological methods were used in the study grain size analysis was also performed finally the content of caco 3 fe 2 co 3 and c org was assessed the research produced a sequence of paleoenvironmental conditions which were then compared with dated loess profiles from western and central europe and russia it was noted that the sequence of paleoenvironmental conditions determined in this study matched that previously identified for the european loess belt including the period from the eemian interglacial to the end of the weichselian glaciation the research results are a contribution to the discussion of the paleoenvironmental significance of loess fossil soils cryogenic structures and slope deposits in addition research has shown that micromorphological analysis is a valuable research tool in soil science and sedimentology

recognition of cryoturbation for classifying permafrost affected soils cryoturbation is a dominant pedologic process in permafrost affected soils and is used to delineate gelisols in soil taxonomy and cryosols in the canadian and recently proposed world reference base for soil resources and cryozems in russian systems of soil classification in this paper we summarize evidence for cryoturbation that can be used for classifying soils containing permafrost based on a literature review and our own observations cryoturbation in the soil profile is manifested by irregular and broken horizons and textural bands involutions organic matter accumulation on the permafrost table oriented stones silt caps and accumulations and deformed soil material associated with movements due to ice and sand wedge growth

podzol formation in sandy soils of finland abstract podzolization occurs quickly in acidic parent materials with addition of acidic litter from coniferous trees this study was conducted to evaluate podzol formation and estimate lengths of time required to meet morphological and chemical criteria of podzolic b horizon and spodic horizon in finland soil color organic c odoe and extractable al and fe were measured in a seven pedon chronosequence 230 1800 years and four older pedons 8300 11 300 years the bulk mineralogical composition of the bc and c horizons was uniform with quartz plagioclase and k feldspar as main components and amphibole illite and chlorite as minor components the fine

porphyroblast rotation eppur si muove in a number of recent papers the theory has been postulated that porphyroblasts as a rule do not rotate with respect to geographical coordinates and can be used to determine the original orientation of older foliations complex inclusion patterns in spiral garnets have even been used to advocate a new model of orogenesis involving several alternating phases of horizontal shortening and extension critical assessment of the assumptions and data used to support the theory of irrotational porphyroblasts reveals numerous flaws millipede structures used as proof for flow partitioning can also form by other flow geometries evidence quoted to support irrotational behaviour of porphyroblasts is unsound porphyrobl asts do occur in sets with a preferred orientation of the internal foliation trace but these cannot be shown to represent original orientations microstructures which resemble truncation planes in spiral garnets are used as evidence that these structures developed by several phases of deformation and as proof for periodic extension and horizontal shortening in orogenesis they can however also be explained by intermittent growth of a rotating porphyroblast during a single phase of deformation finally porphyroblast sets in which orientation is a function of aspect ratio indicate that porphyroblast rotation with respect to kinematic axes does occur in at least some situations

physical and logistical considerations of using ultrasonic anemometers in aeolian sediment transport research abstract recently ultrasonic anemometers uas have become available for precise high frequency measurement of three dimensional velocity and turbulence properties except for a few wind tunnel and computational fluid dynamics cfd simulations advances in aeolian sediment transport and bedform research have been limited to field studies using instrumentation that is either incapable of measuring turbulence e g cup anemometers or unable to withstand sediment laden airflow e g hotfilms in contrast extensive progress has occurred in fluvial research where turbulence instrumentation has been available for some time this paper provides a pragmatic discussion on using uas in aeolian research recent advances using this technology are reviewed and key physical and logistical considerations for measuring airflow properties and near surface shear stress using uas over complex terrain are discussed physical considerations include limitations of applying boundary layer theory to flow over natural surfaces such as non logarithmic velocity profiles resulting from roughness and topographically induced effects and the inability of instrumentation to measure within the thin constant stress region these constraints hinder accurate shear velocity u shear stress and sand transport estimation uas allow measurement of turbulent reynolds stress rs that in theory should equal profile derived shear stress discrepancies often exist between these quantities however due to three dimensional spanwise flow components and rapid distortion effects i e unbalanced production and dissipation of turbulence common in flow over complex terrain while the rs approach yields information on turbulent contributions to near surface stress generation little evidence exists showing that rs is a better measure of forces responsible for sediment transport consequently predictive equations for sediment transport using rs do not exist there is also a need to identify the role of micro turbulent events e g burst sweep cycles and macro turbulent structures e g separation cells shear layers in aeolian dynamics in field settings to validate recent wind tunnel and cfd simulations a conundrum exists regarding whether velocity data should be rotated to correct for potential sensor misalignment effects in unsteady non uniform flow over complex terrain streamline angles vary spatially and temporally with height and location thus determination of and correction to true streamline coordinates is difficult caution should be exercised with correction methods that remove implicit vertical velocity trends as this may preclude detection of geomorphically important flow behaviour e g lift at a dune crest and may complicate interpretations of rs instruments should be aligned with the underlying surface and flow visualization should be used to adjust sensor measurement planes as close as possible to local streamlines logistical considerations include sensor design advantages and operational limitations data communication formats and field deployment strategies each can affect measurement accuracy and are easily overlooked sampling range frequency and period are also important as they limit the range of velocities and scales of turbulence that can be characterized ultrasonic anemometers offer a new sampling resolution to measure turbulent airflow properties in field settings with proper considerations of their limitations uas may allow researchers to close the gap between fluvial research and develop more robust models of aeolian processes and morphodynamics

timing of the late vistulian weichselian glacial phases in poland abstract the lower vistula region in northern poland is a stratotype area for the vistulian weichselian glaciation and during last glacial maximum lgm the southernmost extension of the scandinavian ice sheet occurred in western poland and in eastern germany reinterpretation of the available geochronological data radiocarbon 36 cl and 10 be ages supplied with new field geological evidence mostly for the late vistulian ice sheet limits and movement directions was focused in three key regions in poland during the late middle vistulian there was one or two ice sheet advances in the lower vistula region the late vistulian maximum ice sheet limit in poland was time transgressive and occurred at 24 19 kyrs bp generally the younger to the east ice sheet limits during the leszno phase occurred at 24 cal 10 be 36 cl kyrs the poznan phase ice sheet limit was dated to 19 10 be 36 cl kyrs and the pomeranian phase ice sheet limit about 16 17 10 be 36 cl kyrs every late vistulian glacial phase in poland was preceded by an ice sheet retreat

geochemistry of the active layer and near surface permafrost mackenzie delta region northwest territories canada the soluble ion content of the active layer and near surface permafrost was determined at 41 sites in the mackenzie delta region northwest territories canada in delta soils ca2 and mg2 are the dominant soluble cations but the quantity and relative abundance of na increase with proximity to the beaufort sea coast soils beneath frequently flooded surfaces are ion rich in comparison with ground above the level of decadal flooding within a terrain type near surface permafrost soil solute concentrations are similar between paired cores spaced 1 m apart but at greater distances cores spaced 3 13 m apart solute concentrations are significantly different comparatively low soil solute concentrations in old upland surfaces near inuvik may be a result of progressive removal of soluble materials from the active layer and permafrost during periods of deeper thaw in sandy silt alluvium solutes excluded during downward freezing may accumulate at the base of the active layer and be sequestered by a ris

palaeosols and their cover sediments of a glacial landscape in northern central europe spatial distribution pedostratigraphy and evidence on landscape evolution abstract knowledge of the distribution types and properties of buried soils i e palaeosols is essential in understanding how lowlands in northern central europe have changed over past millennia this is an indispensable requirement for evaluating long term human impact including soil erosion and land cover dynamics in the serrahn area 62 km2 a young glacial landscape representative for northeastern germany and part of the muritz national park 26 pedosedimentary sections were documented and analysed to this end a multiproxy approach was applied using pedology micromorphology geochronology and palaeoecology statistical and spatial analyses of c 5200 soil profiles of which 10 contain palaeosols show that buried soils cover an area of 5 7 km2 i e 9 of the area studied most palaeosols are cambisols arenosols and gleysols palaeosols are mainly covered by aeolian and colluvial sands as well as by lacustrine sands and peat radiocarbon and luminescence dating together with palynological and anthracological data reveal that former land surfaces were dominantly buried through erosion triggered by human activity in the late holocene in addition but to a clearly smaller extent lateglacial early holocene palaeosols and cover sediments occur following medieval clear cutting and intensive land use the study area is today again widely forested the high share of buried land surfaces detected here is expected to be representative for the hilly glacial landscapes even in the wider region i e in northern central europe and should be considered in soil mapping soil carbon budgeting and assessments of past human impact

temperature time relationships across metamorphic zones evidence from porphyroblast matrix relationships in progressively deformed metapelites abstract in a rock pile undergoing prograde regional metamorphism the isotherms corresponding to certain metamorphic reactions shift continuously while the same rock volume develops progressive deformation fabrics as a result of increasing strain porphyroblasts in pelitic schists can provide crucial information on both these aspects of metamorphism not only do they reflect the pressure temperature evolution of that terrain but their inclusion trails are clues to the state of deformation at the time of porphyroblast growth microstructural relationships of inclusion trail patterns versus matrix foliations combined with petrological data on prograde reaction sequences can be used to reconstruct temperature time relationships in different zones within metamorphic terrains in two proterozoic areas in northern queensland the western mary kathleen fold belt and the robertson river subgroup a systematic variation of inclusion trail patterns has been found across metamorphic zones each porphyroblast species contains more advanced stages of s 2 foliation development towards its isograd compared with higher grade zones in which these porphyroblasts are present the combined microstructural petrographic observations allow to place constraints on the t t evolution of the various zones the regional distribution of inclusion trail patterns in the two study areas indicates that deformation affected high and low grade zones simultaneously

human impact on subatlantic slopewash processes and landform development at lake jasien northern poland abstract a survey of the lake jasien area northern poland demonstrates the relationship between human economic activity and the course of slopewash processes during the subatlantic in the catchment area of the erosional denudational valley affected by prolonged human economic activity in the early iron age the hallstatt period and the pre roman period deforestation may have led to activation of hillslope processes a manifestation of this activation is a fossil cut in the bottom of the valley and sediments of hillslope origin filling it lying on top of sediments dated to 450 bc 100 cal ad the intensity of the hillslope processes may have been modelled by climate changes involving cooling and humidification the most recent documented increase in the intensity of denudation occurred around the middle of the 17th century deposited on top of sediments dated to 1456 ad 1638 cal ad and 1453 ad 1797 cal ad is a sequence of hillslope sediments developed in the form of diluvium and tillage diamicton filling the bottom of the valley and the closed depression faster denudation in the landform catchments and accumulation on their bottoms were caused by deforestation of those areas and using them as farmland as indicated by old cartographic materials the cooling and humidification of the climate during the little ice age may also have contributed to the acceleration of the agrotechnical denudation in areas unaffected by deforestation no noticeable traces have been found of active denudation processes during the subatlantic this may suggest that hillslope processes did not play a major role in lowland forested areas of the temperate zone

the evidence of lateral podzolization in sandy soils of northern poland abstract evidence of slope scale element translocation lateral podzolization has been documented in sandy areas of northern poland accumulative soils enriched with organic matter iron aluminum and manganese entic podzols have been found at the bottom of closed small depressions in inland dune fields and undulated surfaces of glaciofluvial terraces together with the surrounding weakly or moderately developed podzolic soils albic arenosols haplic podzols entic podzols form regular toposequences and seem to be geochemically linked in the light of chemical micromorphological and sem eds analyses the whole solum of the soils under study exhibit diagnostic features of the illuvial spodic horizon however they do not have an eluvial albic horizon landscape position and features of the studied soils suggest inter pedon translocation of organic matter iron and aluminum as the concept of entic podzol genesis furthermore high values of fe d fe t and fe o fe d ratios in their solum can be interpreted as evidence of allochtonous character of iron accumulation the results of this study show that the lateral podzolization process can be common even along slopes built from loose permeable sandy deposits where one would not expect any effective intra layer solution flow organic matter and compounds illuviated to the bhs horizon are the probable factors limiting percolation and modifying the direction of solutions movement on slopes of more complex morphology small closed depressions act as geochemical traps where compounds leached from the upper slope soils can accumulate radiocarbon dating carried out on a buried entic podzol found in one of the profiles shows that the process has continued for more than 1200 years

the himalayan main central thrust pile and its quartz rich tectonites in central nepal as a consequence of the india asia collision a deeply rooted crustal slice has been moved southwards over the northern boundary of the indian plate at the present level of observation the main central thrust pile a rock pile of several kilometers thickness is affected by shear deformation which imprinted a flat foliation and a constant n s trending lineation these tectonites were deformed under a wide range of metamorphic conditions grading from lower greenschists up to the sillimanite field the m c t shear zone is studied from the view point of the quartz rich rocks over 100 samples helped to define a microstructural zonation roughly parallel to the thermal one 35 samples particularly rich in quartz have been used for the preferred orientation study of their c axes and a few of them for their a axes strong lattice orientations when undisturbed by mainly secondary recrystallization attest to large plastic strains in quartz the c axes are mostly distributed along unequally populated crossed girdles which may evolve into an inclined single girdle the a axes concentrate perpendicular to the more populated girdle concerning quartz the following is suggested 1 1 the deformation has a dominant shear component responsible for the dominant stretching lineation it could be simple shear in case of inclined single girdles 2 2 one set of a axes line up parallel to the shear direction slip on various planes in the a direction may be an important deformation mechanism 3 3 asymmetry in the lattice preferred orientations could be used to predict the sense of shear for the himalayan thrusting in more than 80 of cases

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

development of snowball structure numerical simulation of inclusion trails during synkinematic porphyroblast growth in metamorphic rocks abstract this paper presents a hydrodynamic analysis that simulates the development of snowball structures in porphyroblasts the porphyroblast is represented by a rigid sphere that grows at a constant volumetric rate while the matrix is represented by a newtonian fluid that deforms by simple shear well away from the sphere the marker particles used to track the motion of matrix and porphyroblast are arranged in a straight line before deformation those in the matrix move along flow lines that deflect around the sphere while those in the sphere passively rotate at a constant angular velocity those in the matrix are progressively captured and incorporated within the growing sphere the resultant trails of the marker particles in the sphere simulate the inclusion trails of synkinematic porphyroblasts three main types of trails are distinguished by the appearance of curvature in the sphere single double and triple rotation types single rotation types show very simple spiral trails formed when the initial angle between the marker line and the shear plane is between 0 and 45 double rotation types show a complicated pattern with the marker line showing a reversal of curvature from the porphyroblast center to its margin this type is formed when the angle between the marker line and the shear plane was initially between 45 and 135 when this angle exceeds 135 then triple rotation types appear which are characterized by two reversals of curvature of the marker line from center to the margin the calculated results are found to be very similar to some natural examples implying that such natural spiral patterns in the porphyroblast are produced in the similar way to what happens in the computer simulation

the black floodplain soil in the amoneburger becken germany a lower holocene marker horizon and indicator of an upper atlantic to subboreal dry period in central europe abstract in many sediment profiles of central european floodplains a black horizon is found between late glacial and middle to upper holocene sediments this horizon is rich in clay and humic material and is referred to as black floodplain soil bfs its widespread occurrence in the amoneburger becken near marburg hessen provides some new insights into the period and circumstances of its development as a polygenetic formation the bfs is of special importance for paleoecological and archeological research it was probably supplied with clay and humic substances from the surrounding terrestrial chernozemic soils and therefore it also has to be regarded as a sediment it developed mainly in the boreal and atlantic periods but did not gain its final characteristics until a following dry period which led to a lowering of the ground water table and widespread illuviation in the floodplains even in former lacustrine deposits