crustal structure due to collisional and escape tectonics in the eastern alps region based on profiles alp01 and alp02 from the alp 2002 seismic experiment 1 alp01 and alp02 are the longest profiles recorded during alp 2002 a large international seismic refraction and wide angle reflection experiment undertaken in the eastern alps in 2002 alp01 crosses the alpine orogen from north to south thus providing a cross section mainly affected by the collision between europe and the adriatic microplate alp02 extends from the eastern alps to the pannonian basin supplying evidence on the relation between alpine crustal structure and tectonic escape to the pannonian basin during this experiment 363 single channel recorders were deployed along these profiles with an average spacing of 3 2 km recordings from 20 inline shots were used in this study two dimensional forward modeling using interactive ray tracing techniques produced detailed p wave velocity models that contain many features of tectonic significance along alp01 the european moho dips generally to the south and reaches a maximum depth of 47 km below the transition from the eastern to the southern alps the adriatic moho continues further south at a significantly shallower depth moho topography and a prominent south dipping mantle reflector in the alpine area support the idea of southward subduction of the european lithosphere below the adriatic microplate the most prominent tectonic feature on the alp02 profile is a vertical step of the moho at the transition between the alpine and pannonian domains suggesting the existence of a separate pannonian plate fragment the development of the pannonian fragment is interpreted to be a consequence of crustal thinning due to tectonic escape from the alpine collision area to the pannonian basin

relict non glacial surfaces in formerly glaciated landscapes abstract relict non glacial surfaces occur within many formerly glaciated landscapes and contain important information on past surface processes and long term landscape evolution relict non glacial surfaces are distinguishable from glacial surfaces by large scale morphologies including rounded summits fluvial valleys and cryoplanation terraces and pediments and the presence of tors blockfields and or saprolites preservation during glaciation occurs either through coverage by non erosive cold based ice or as nunataks although surface morphologies and denudation rates indicate a continuous non glacial surface history since preglacial times relict non glacial surfaces are dynamic features that have evolved during the quaternary depending on spatial variables such as lithology slope regolith depth and the abundance of fine matrix and water some surfaces are denuding very slowly while others display more rapid denudation high spatial variability in denudation rates results in changing surface morphologies over time denudation rates also display high temporal variability with much surface evolution having perhaps occurred soon after the initial onset of glaciation or during paraglacial phases while some parts of non glacial landscapes are currently active others may be largely inactive relicts of past higher energy regimes although non glacial surfaces are dynamic much remains to be determined regarding surface denudation rates and the magnitude of morphological changes over time

effects of acidic and basic parent materials on formation of some soils in quebec canada abstract five profiles developed on basic or acidic parent materials were sampled in southern quebec canada physical chemical and mineralogical properties were determined among the three profiles developed on basic parent materials one formed in disaggregated metabasalt whereas the two others developed in preglacial saprolites derived from the metabasalt as indicated by till cover in a nearby area in the lower part of the latter profiles the saprolites had a loamy texture and the mineralogical plus chemical data indicated very slight changes with respect to the metabasalt in these profiles cbd extractable fe content was 1 in most horizons and the pyrophosphate extractable fe was generally higher in the ah than in the b horizons in the profiles developed on acidic till cbd extractable fe was 1 only in the b horizons which also contained the maximum of pyrophosphate extractable fe in the latter profiles free fe and al sesquioxides were associated with the clay fractions whereas in the former profiles one third of the fe came from the sand and silt fractions chlorite was the dominant phyllosilicate in the basic material and it was transformed into interstratified minerals and smectite several hypotheses about smectite formation and distribution were discussed in the profiles developed on acidic till illite and chlorite were the major phyllosilicates and through weathering transformed into interstratified minerals vermiculite and smectite major differences in the properties of the profiles developed on the two parent materials were not reflected by current soil classification

genesis of altered conway granite grus in new hampshire usa abstract increased pedologic interest in grus has created a need for better understanding of geologic and pedogenic processes producing such materials progress in this area is hindered by the incomplete understanding of pedogenic processes as well as the fact that some of the properties of grus may be created through any of several pathways hydrothermal alteration is one important example of a geologic process which may produce characteristics similar to those created by pedogenesis this process is not often considered by soil scientists because of their unfamiliarity with the geologic environments which engender such conditions and the petrographic evidence specific to these processes this study uses petrographic evidence of microfracturing silicification and sericitization indicative of hydrothermal alteration in conjunction with igneous structural geology to enhance traditional pedologic assessments of weathering and soil genesis in the conway granite grus this interdisciplinary approach led to the interpretation that the grus was a product of hydrothermal alteration rather than paleopedogenesis as had been proposed previously more importantly this study demonstrates that interpretations of soil weathering paleosol occurrences and grus genesis in a variety of locations can be enhanced by such considerations

postglacial and pre last glacial weathering of till on the high plateaus of central gaspesie quebec canada geochemical data from mineral exploration surveys are used to assess postglacial and pre last glacial weathering on the high plateaus of central gaspesie by comparing the distribution of 30 elements in the b and c horizons of a thin soil developed on glacial deposits under postglacial weathering fe2o3 tio2 p2o5 cr li u and v are immobile relative to al2o3 whereas the other elements are mobile and have been depleted to various degrees from the b horizon loss on ignition value is the only parameter showing a significant enrichment from the c to the b horizons the apparently high degree of geochemical weathering of the glacial deposits in respect to their source bedrock lithologies suggests that the deposits also contain previously weathered material the spatial distribution of the geochemical weathering index values calculated for the c horizon shows no clear relation to the underlying bedrock formations the high values are located on topographic highs with maxima over deeply weathered bedrock

variability within a saprolite deposit near quebec city canada samples were collected in two trenches opened in a saprolite developed in a mylonite derived from biotite garnet gneiss near quebec city in order to investigate the spatial variability from the points of view of morphological physical mineralogical and chemical properties phyllosilicate assemblages were a kaolinite b mica c kaolinite mica and d mica interstratified minerals smectite grouping of the samples according to prominent colour in the matrix showed a relation between chroma and kaolinite content total chemical analyses were in good agreement with mineral assemblages the spatial distribution of these assemblages corresponded to the degree of transformation of the gneiss into mylonite

subsidence analysis and quantitative basin modelling in the styrian basin pannonian basin system austria abstract we present the results of subsidence analysis and of quantitative basin modelling using isostatical and flexural models for basin evolution along four cross sections in the styrian basin the westernmost subbasin of the pannonian basin system subsidence analysis reveals a first ottnangian karpatian synrift phase our local isostatic models predict crustal stretching values up to 1 3 and subcrustal stretching values of 1 6 for this event stretching factors of a minor sarmatian extension phase are below 1 04 the termination of subsidence during the pannonian and a rapid quaternary uplift phase can be explained by major changes in the regional stress field a w e cross section through the northern furstenfeld subbasin provides a key for the understanding of the dynamics of basin formation it crosses a narrow karpatian rift basin the metamorphic core complex of the penninic eisenberg window and shows an eastward tilting of the easternmost part of the basin during pannonian times uplift of the penninic window can only be modelled with an extremely weak lithosphere equivalent elastic thickness eet 2 km whereas a best fit between observed and modelled tilting is obtained with an eet value of 5 km these results suggest that the lithosphere was extremely weak during the onset of basin evolution in ottnangian karpatian times probably caused by high extension rates and high heat flows associated with karpatian to early badenian magmatic activity subsequent cooling led to a pronounced increase in flexural rigidity an eet of 5 km fits well with estimations in other parts of the pannonian realm depth dependent rheology models based on palaeo heat flow estimates indicate a similar increase in lithospheric strength with time the impact of plio pleistocene volcanism on rheology appears to be relatively modest which can be explained by a deep position of the magma chamber for this event

regolith residence time and the concept of surface age of the piedmont peneplain the common upland weathering profile on foliated metamorphic rocks on the appalachian piedmont between alabama and maryland includes a 50 cm 1 m thick clay rich soil b horizon over 10 20 m of saprolite the saprolite retains the volume fabric and structure of the underlying parent rock but has lost about one third of the mass of the parent rock where the saprolite is thickest beneath upland drainage divides those divides are of loow slope and relief the flatness of the piedmont drainage divides provides the appearance of a planation surface of accordant summits or peneplain i interpret this flatness to be the result of three active processes volume reduction during compaction of saprolite into soil loss of mass in dissolved solids draining the soil b horizon and loss of mass from the soil surface by erosion of clay size particles the cumulative effects of these upland processes are to convert saprolite into soil to limit soil thickness and residence time and to limit the age of the oldest residual soils on the surface this results in a continual lowering of the piedmont peneplain surface this interpretation is corroborated by evidence of topographic inversion of fluvial gravels since the miocene near the fall line study of baseflow dissolved solids draining piedmont basins indicates a minimum rate of saprolite production of about 4 m ma 1 this minimum rate of production near the fall line is less than the estimated rate of surface lowering and saprolite consumption during the late tertiary and quaternary periods of topographic inversion measurement of cosmogenic 10be inventories in two 15 20 mores of piedmont upland regolith indicate a minimum residence time of residual soil and saprolite of about 1 ma this indicates a possible maximum rate of saprolite production and erosion of about 20 m ma 1 using the best available evidence therefore the typical piedmont upland regolith has a residence time of between 1 and 5 ma residence times may not be the same everywhere and ages may vary systematically across the surface the geomorphic evidence of topographic inversion and similar regolith profiles in other humid temperate and tropical regions strongly suggests that production and removal of piedmont saprolite has been an ongoing quaternary process and that most of the piedmont regolith is significantly younger than 5 ma independent geophysical evidence suggests that the rate of uplift probably involving tilting of parts of the piedmont blue ridge and valley and ridge has averaged between 5 and 20 m ma 1 through the cenozoic

orogen parallel strike slip faults bordering metamorphic core complexes the salzach enns fault zone in the eastern alps austria abstract the approximately ene trending salzach enns fault eastern alps contributed to late stage exhumation of the tauern metamorphic core complex in response to oblique convergence of european and adriatic plates six stages of kinematic evolution with early ductile and later brittle deformational structures were recognized as follows 1 initial ductile deformation is represented by a combination of sinistral shear dominated noncoaxial strain and coaxial strain 2 early brittle sinistral strike slip is combined with a pure shear deformation and represents roughly n s contraction it is followed by 3 sinistral strike slip and 4 ca n s extension due to normal slip striations 5 subsequent n s compression resulted in counterclockwise rotation of the maximum principal stress from ne to nw and led to final dextral strike slip displacements along the salzach enns fault the exhumation of the tauern window was accommodated by dip slip on the fault plane at shallow levels and coaxial flattening at deeper structural levels brittle sinistral faults at shallow structural levels produced a larger amount of strike slip displacement than ductile shear zones at the deeper structural levels which is explained as a scissors like movement and which resulted in the eastward tilting of the tauern window

eastern alpine tectono metamorphic evolution constraints from two dimensional p t t modeling we use two dimensional 2 d p t t modeling to constrain the thermal and rheological aspects of different scenarios for the late mesozoic and cenozoic tectonic evolution of the eastern alps inferred from excellent data sets from the tauern window tw models invoking subduction of the south penninic sp oceanic lithosphere during thrusting and subsequent erosion of the austro alpine aa upper plate nappe stack are inconsistent with the observed thermal evolution within the aa and penninic units in these models predictions for the aa peak thermal conditions are lower than observed after exhumation and cooling to midcrustal levels and subduction of the continental middle penninic mp block the aa undergoes a phase of renewed heating to almost the previous peak temperatures simultaneously the penninic units experience a phase of heating upon subduction followed by cooling after onset of subduction of the north penninic np basin the model predictions are inconsistent with the observed nearly isothermal uplift path of the sp after subduction and cannot explain observed inverted metamorphic peak conditions in the deeper aa amphibolite facies down to the higher penninic unit greenschist facies a model with the beginning of subduction of the sp occurring after crustal thickening of the aa and subsequent return to normal crustal thicknesses is compatible with the p t t data in this model peak temperature conditions are higher in the aa followed by a phase of strong cooling in the aa upper plate with the onset of underthrusting this model also explains successfully nearly isothermal exhumation of the mp and inverted metamorphic peak conditions in the deeper aa material accreted to the hanging wall from the oceanic crust sp experiences a phase of cooling during ongoing subduction of oceanic lithosphere and begins to heat up to its thermal climax after the subduction of trailing continental lithosphere the subsequent pt path of the penninic units strongly depends on the timing and rates of underthrusting by the foreland observed pt paths in the mp within the tw require continuous subduction of the np and the trailing european foreland under the exhuming mp block documented rapid cooling in the final uplift phase of the penninic units in the tw requires exhumation rates up to approximately 4 mm yr predictions of slightly elevated present day geothermal gradients in the tw area are consistent with available heat flow data as a result of mesozoic rifting followed by late mesozoic crustal thickening of the aa paleorheological reconstructions are characterized by a contrast between relatively strong oceanic lithosphere and adjacent weak continental lithosphere predicted decoupling of weak continental and oceanic lithosphere during subsequent subduction of the penninic units can explain observed late cretaceous crustal extension in the aa units in terms of gravitational spreading ongoing subduction leads to an overall strength increase due to underthrusting of cool oceanic lithosphere whereas subduction of continental lithosphere causes a strength decrease in the upper levels of the lithosphere continuous crustal thickening and relaxation of the depressed isotherms reduce the strength of the lower lithospheric mantle beneath the central orogen further enhanced by rapid late stage uplift predictions for the present day rheological structure of the eastern alps support the existence of a strong upper crustal layer two wedge shaped strong upper mantle layers to the north and the south of the orogen and a weak upper mantle underlying the central orogen

lateral extrusion in the eastern alps part 1 boundary conditions and experiments scaled for gravity lateral extrusion encompasses extensional collapse gravitational spreading away from a topographic high in an orogenic belt and tectonic escape plane strain horizontal motion of wedges driven by forces applied to their boundaries in the eastern alps it resulted from 1 an overall northerly compression apulia against eurasia 2 a strong foreland bohemian massif 3 lack of constraint along a lateral boundary carpathian region and 4 a previously thickened gravitationally unstable thermally weakened crust eastern alpine orogenic belt six indentation experiments reproduce lateral extrusion at lithospheric scale the models have two to four lithospheric layers with a mohr coulomb rheology for the upper and a viscous rheology for the lower crust the lithosphere rests upon a low viscosity asthenosphere a broad indenter a narrow deformable area and a weakly constrained eastern margin fullfill as closely as possible conditions in the eastern alps indentation produces both thickening in front of the indenter and escape of triangular wedges lateral variations in crustal thickness become attenuated by gravitational spreading the overall fault pattern includes domains of reverse strike slip oblique normal and pure normal faults strike slip faults in conjugate sets develop serially the narrow width of the deformable area and the strength of the foreland determine the angles between the sets gravitational spreading produces a rhombohedral pattern of oblique and pure normal faults along the unconstrained margin opposite the unconstrained margin the indenter front shows thrusts and folds intersecting with the conjugate strike slip sets a triangular indenter favors spreading high velocity of indentation favors escape high confinement limits lateral motion inhibits spreading and favors thickening lateral extrusion in the eastern alps is best modeled by 1 a weak lateral confinement 2 a broad and straight indenter 3 a narrow width of the deformable area and 4 a rigid foreland crustal thickening lateral escape and gravitational spreading all contribute to the overall deformation

continental collision with finite indenter strength 2 european eastern alps 1 comparison of the results of a thin viscous sheet model with the velocity field determined by gps stations in the alpine pannonian realm shows that the adriatic plate is only slightly stronger than the eastern alps the observed velocity field is best approximated with a newtonian fluid however this scenario must be fairly recent as the overall geometry of the orogen can only be reproduced if the rheology contrast was about 1 10 before the late miocene the boundary conditions for this model are tested against the orientation of the intraplate stress field and are robust for argand numbers between 1 and 5 we conclude that the convergence rate between the adriatic and european plates must have slowed since the miocene and that the present day eastward extrusion of the eastern alps is largely due to lateral escape and only to a minor degree due to gravitational collapse scaled viscosities of the eastern alps are on the order of 1023 pa s

focal mechanism inversion in the giudicarie lessini seismotectonic region southern alps italy insights on tectonic stress and strain abstract a set of 41 focal mechanisms 1989 2006 from p wave first polarities is computed from relocated seismic events in the giudicarie lessini region southern alps estimated hypocentral depths vary from 3 1 to 20 8 km for duration magnitudes md in the range 2 7 5 1 stress and strain inversions are performed for two seismotectonic zones namely g giudicarie and l lessini this subdivision is supported by geological evidence seismicity distribution and focal mechanism types the available number of data 16 in g 22 in l does not make possible any further subdivisions seismotectonic zones g and l are undergoing different kinematic regimes thrust with strike slip component in g and strike slip in l principal stress and strain axes in each sub region show similar orientations the direction of maximum horizontal compressive stress is roughly perpendicular to the thrust fronts along the giudicarie belt in zone g and compatible with right lateral strike slip reactivation of the faults belonging to the schio vicenza system in zone l on the whole kinematic regimes and horizontal stress orientations show a good fit with other stress data from focal mechanisms and breakouts and with geodetic strain rate axes

age and prematurity of the alps derived from topography abstract the european alps are one of the best studied mountain ranges on earth but yet the age of their topography is almost unknown even their relative stage of evolution is unclear are the alps still growing in a steady state or already decaying and is there a significant difference between western and eastern alps using a new geomorphic parameter we analyze the topography of the alps and provide one of the first quantitative constraints demonstrating that the range is still in its infancy in contrast to several other mountain ranges the alps have still more than half of their evolution to a geomorphic steady state to go combining our results with sediment budget data from the surrounding basins we infer that the formation of the present topography began only 5 6 million years ago our results question the apparent consensus that the topographic evolution is distributed over much of the miocene and might give new impulses to the reconstruction of paleoclimate in central europe

exhumation in a convergent orogen the western tauern window unroofing of the western tauern window involved both low angle detachment faulting brenner fault and enhanced footwall erosion contemporaneous with upright antiformal folding this combination reflects orogen parallel e w extension during continued n s alpine convergence new fission track ages establish the relative chronology of folding and faulting and demonstrate that displacement was not always accommodated on the same surface during exhumation some units migrated from the footwall to the hanging wall of the main detachment fault due to the interplay between folding and faulting the region can effectively be divided into 3 distinct domains 1 the penninic units of the western tauern window were always in the footwall to the fault with maximum exhumation in the core of the dome due to folding and erosion 2 the lower austroalpine unit north of the tauern window was first part of the hanging wall to the brenner fault at a later stage this unit was exhumed by a further 4 5 km as part of the footwall to a more discrete through going fault the silltal fault 3 the middle and upper austroalpine units west of the tauern window were always within the hanging wall exhumation of the footwall from an initial depth of 25 km led to a transition in mechanical behaviour the curviplanar folded ductile shear zone marking the boundary to the tauern window was eventually transected by a more planar discrete brittle fault silltal fault with unit 2 now in the footwall along which the pre existing mylonites were passively exhumed to the surface

estimating displacement along the brenner fault and orogen parallel extension in the eastern alps the major structure accommodating orogen parallel extension in the eastern alps is inferred to be the brenner fault which forms the western boundary of the tauern window the estimated amount of extension along this fault varies from a minimum of 10 20 km to a maximum of 70 km all investigations that have attempted to constrain this amount of extension have calculated the fault plane parallel displacement required to restore the difference in structural level between footwall and hanging wall as constrained by geobarometry however these calculations neglected the component of exhumation of the footwall resulting from folding and erosion therefore the total amount of extensional displacement was systematically overestimated in the present study we project a tectonic marker surface from the footwall and hanging wall of the brenner fault onto a n s striking cross section this marker surface which is the base of the patscherkofel unit in the footwall and the base of the otztal basement in the hanging wall is inferred to have occupied the same structural level in the hanging wall and footwall of the brenner fault before its activity therefore the difference in height between the marker projected from the footwall and from the hanging wall is a measure of the vertical offset across the brenner fault this construction shows that the vertical offset of the marker horizon on both sides of the brenner fault varies strongly and continuously along strike of the brenner fault attaining a maximum value of 15 km at the hinge of the folded footwall tauern dome the along strike change of vertical offset is explained by large scale upright folding of the footwall that did not affect the hanging wall of the brenner fault therefore the difference in vertical offset of 10 km between the area of the brenner pass and the area immediately south of innsbruck corresponds to the shortening upright folding component of exhumation of the footwall the remaining 5 km of vertical offset must be attributed to extensional deformation the brenner fault itself is barely folded its dip varies between 20 and 70 and it crosscuts the upright folds of the western tauern window given the offset of 5 km the dip of the fault constrains the extensional displacement to be between 2 and 14 km we conclude that the tauern window was exhumed primarily by folding and erosion not by extensional unroofing

a review of the thermal regime of the eastern alps with respect to the effects of paleoclimate and exhumation abstract transient thermal signals such as pleistocene surface temperature variations or exhumation of great rock volumes are important for the current thermal regime of the eastern alpine crust in this study transient 1 d forward simulations and an analytical approach were used to estimate the order of magnitude of these effects a comparison with numerical forward simulations and inverse analyses of steady state heat conduction yields the following main conclusions with respect to the thermal regime of the eastern alps along the transalp profile 1 the change of surface temperatures in the past affects mainly the uppermost part of the eastern alpine crust it results in a maximum thermal signature of more than 6 k at a depth of 2 km the deviations from a steady state temperature gradient and heat flow in the region of the tauern window range from 0 3 4 k km 1 and 0 6 mw m 2 respectively with maximum values at the surface 2 exhumation of the eastern alpine lithosphere may result in a thermal signature of up to 4 k at a depth of 1 km the thermal signature increases further with depth to a maximum of approximately 80 k at a depth of 50 km as the temperature gradient of the exhumation signal is almost zero at the base of the crust moho heat flow appears to be not critically perturbed 3 the combined effect of exhumation and changing surface temperatures at the tauern window amounts to less than 15 of the steady state temperatures at a depth of 8 km and to less than 10 at the base of eastern alpine root the corresponding perturbation in heat flow is less than 20 at a depth of 4 km approaching zero below 40 km

climate variations and the appalachians from the late paleozoic to the present results from model simulations abstract a series of climate model simulations are utilized to examine the climate evolution of the appalachians from the carboniferous to the present through consideration of large scale changes in paleogeography and potential variations in carbon dioxide on long time scales the model simulations predict considerable variations in temperature and precipitation through time in addition a number of shorter time scale phenomena may influence the climatic record of the appalachians in particular milankovitch orbital variations can produce rhythmic climate and weathering particular geographic configurations since the carboniferous tend to promote sensitivity to orbital variations although far from comprehensive the model simulations provide independent predictions of climate which can be utilized to investigate the evolution of the appalachians deductively

thermal history of tertiary basins in slovenia alpine dinaride pannonian junction abstract the transition zone between the alps the dinarides and the pannonian basin was affected by syn collisional magmatism in oligocene time and post collisional lateral escape followed by extreme extension in early and middle miocene times numeric heat flow models for sixteen sites and 650 vitrinite reflectance data from paleogene and neogene sediments were used to evaluate temporal and lateral heat flow variations related to these events oligocene oligocene smrekovec volcanism is the main heat source for paleogene sediments south of the periadriatic lineament vitrinite reflectance patterns suggest dextral displacement along the donat fault of the order of 50 km coalification of paleogene coal bearing sequences south of the pohorje is a result of the emplacement of the oligocene pohorje tonalite early middle miocene extremely elevated early middle miocene heat flow 200 mw m2 occurred in the styrian basin the pohorje area the maribor radgona area and along the boc anticline it is partly a consequence of magmatic activity however no igneous rocks are known from the maribor radgona area a large shallow early miocene pluton could explain the observed miocene heat flow rapid uplift of hot basement rocks in the pohorje kozjak region may have increased surface heat flow neither volcanic rocks nor metamorphic core complexes are known from the boc area the ormo selnica anticline was probably influenced by a middle miocene heating event 150 mw m2 coeval volcanism south of the anticline represents a potential heat source post middle miocene the wsw ene trending ljutomer and radgona depressions are characterized by moderate neogene heat flow 60 75 mw m2 whereas late miocene to present day heat flow in the ormo selnica anticline is 80 90 mw m2 a recent heat flow anomaly occurs in the somat benedikt area

alteration profonde preglaciaire d un gneiss a charlesbourg quebec canada abstract a saprolite derived from a gneiss has been sampled in a fault zone at charlesbourg near quebec city the weathering largely exceeding 6 m in depth and a till overburden suggest preglacial alteration under warmer climatic conditions this is further supported by the presence of high up to 15 percentages of crystalline iron oxides goethite and lepidocrocite four different facies were defined in the saprolite mineralogical analyses were performed on the clay fractions and the following associations were found swelling minerals kaolinite kaolinite kaolinite gibbsite swelling minerals kaolinite the degree of weathering of 2 1 minerals into kaolinite seemed to be related to internal drainage conditions cation exchange capacity of the saprolite was adequately explained by the clay and silt fraction contributions

evolution geochimique superficielle naissante des anorthosites cas du profil de château richer quebec canada the initial stages of the superficial geochemical weathering of anorthosites have been investigated in a deposit at ch teau richer quebec the parent rock consists almost exclusively of andesine and is weathered to a thickness of about 120 cm a till overburden indicates that the profile was truncated by the wisconsinian ice the rock is not extensively disintegrated but the chemical weathering is rather intense the parker diagram shows a strong decrease of the weathering index from the parent rock to the weathering zone while this is not the case for other crystalline rocks in the area it may be accounted for by the fragility of the plagioclase the 2 m fraction which amounts to 2 of the soil presents an evolution that is influenced by the site especially the drainage conditions at the base of the profile drainage is poor and 2 1 minerals smectite and vermiculite are present in addition to 40 kaolinite the 1 1 mineral increases to 60 near the contact with the till while the amount of 2

surface kinematics in the alpine carpathian dinaric and balkan region inferred from a new multi network gps combination solution abstract the understanding of the intraplate tectonics of central europe requires a detailed picture of how stress is transferred from the interaction of the eurasian nubian and anatolian plates to the alpine carpathian pannonian and dinaric regions recent strain distribution is controlled by the adria horizontal push by the vrancea vertical slab pull and associated horizontal displacements and by the aegean anatolia extension and slab roll back we present a horizontal velocity field for the alpine carpathian pannonic dinaric and balkan regions resulting from a new combination of seven different gps networks formed from permanent and campaign stations dedicated velocity profiles in two specific regions are studied in detail one is the alpine pannonian region with a detailed picture of the ns indentation of the adria microplate into the southern alps in ne italy the deformation in the tauern window and the eastwards kinematics of a pannonian plate fragment the second study region includes transylvania the southern carpathians up to the aegean sea and albania where a major right lateral shear deformation exists as a consequence of the ne convergence of the apulia platform towards the dinarids and the ssw motion of macedonia western bulgaria and rumania related to the hellenic arc dynamics in the eastern mediterranean the profiles in the alpine pannonian area indicate that a velocity drop of 2 5 0 4 mm yr associated with the adria indentation concentrates on a segment of some 50 km south of the periadriatic fault the deformation becomes extensional by a similar amount just north of the periadriatic fault in the tauern window where the updoming of the tauern window implies vertical motion which could well be associated with surface extension in the ew profile we observe a sudden velocity change of 1 5 0 2 mm yr in 20 km corresponding to the right lateral lavant fault which seems to mark the border between dominant indentation kinematics to the west and dominant extrusion kinematics to the east three profiles are considered in southern and eastern europe one across the lower adriatic sea from apulia in italy to the southern dinarides which enables it to constrain the velocity drop associated with the subduction of the adria microplate into the dinarides to 3 2 0 5 mm yr in 140 km the second profile is longitudinal and constrains the velocity inversion of 7 4 1 0 mm yr in 350 km associated with right lateral shear faults in albania the third profile crosses the transylvania region with a shortening of 2 3 1 0 mm yr in 220 km and the wallachian moesian region up to the chalcidic peninsula in n greece this lower part of the profile implies an extensional stretch of the upper crust of 3 2 0 9 mm yr in 440 km culminating in the hellenic arc strain rate maps are presented in this regional scale showing the excellent agreement between fault plane solutions of crustal earthquakes and the eigenvectors of the gps derived two dimensional strain rate tensor three profiles are considered in the balkan and se carpathians one across the lower adriatic sea from apulia in italy to the southern dinarides which enables to constrain the velocity drop associated to the subduction of the adria microplate into the dinarides to 3 2 0 5 mm yr in 140 km the second profile is longitudinal and constrains the velocity inversion of 7 4 1 0 mm yr in 350 km associated to right lateral shear faults in macedonia a highly seismic region the third profile crosses the transylvania with a shortening2 3 1 0 mm yr in 220 km and the wallachian moesian region up to the chalcidic peninsula in n greece this lower part of the profile implies an extensional stretch of the upper crust of 3 2 0 9 mm yr in 440 km culminating in the hellenic arc

modeling surface gps velocities in the southern and eastern alps by finite dislocations at crustal depths abstract the indentation of the adria plate into the southern and eastern alps is an ongoing collisional process accompanied by seismicity surface and rock uplift and lateral escape we present a 3d quantitative description of the process by combining gps and structural data with an elastic dislocation model horizontal velocities of 70 austrian and italian permanent gps stations in the eastern and southern alps serve as boundary condition on the free surface of an elastic half space containing six rectangular faults each with a uniform slip rate the geometry of the rectangular faults and the slip rate vector are constrained by least squares taking into account the structural setting of the area and the geographic distribution of the velocity data we find that the surface velocities of the order of some mm yr require reverse north side of the tauern window transpressional giudicarie north alpine wrench corridor pustertal dinarides and normal brenner fault slips ranging from 10 to 30 mm yr at crustal depths the regional stress pattern computed from fault plane solutions agrees with the principal directions of our rectangular fault planes the model although constrained by horizontal velocities only predicts a pattern of vertical motion which qualitatively agrees with known phenomena such as the surface uplift in the tauern window area of the order of up to few mm yr if the heat on the shearing fault planes is removed mostly by upwards diffusion the absence of large heat anomalies on the earth s surface suggests for nominal geotherms shear stresses and concentration of subcrustal radiogenic elements that the time of initiation of the slip dates to pliocene hence more recent than late oligocene miocene time of collision of the adria indenter

present day stress field and deformation in eastern austria we analysed fault plane solutions and borehole breakouts in the eastern part of the eastern alps and found a heterogeneous stress field which we interpret as a transition zone of three different stress provinces the western european stress province with nw to nnw sh orientation and mainly strike slip faulting regime the adriatic stress province with a radial stress pattern and thrust faulting to strike slip faulting regime and the dinaric pannonian stress province with ne sh orientation and strike slip faulting regime the western pannonian basin seems to be a part of the transition zone with wnw to nw sh orientation a stress regime stimulating strike slip faulting prevails in the eastern alps the south bohemian basement spur as a major tectonic structure with a high rheological contrast to surrounding units has a strong influence on the stress field and exhibits the highest seismicity at its tip due to stress concentration from a constructed vertical stress orientation profile we found stress decoupling of the northern calcareous alps from the underlying european foreland both the molasse and the flysch helvetic zone are considered as candidates for decoupling horizons due to stress orientation observations and due to their rheological behaviour from seismological and rheological data we suggest a horizontal stress decoupling across the eastern alps caused by a weakened central alpine lithosphere

source parameters and stress release of seismic sequences occurred in the friuli venezia giulia region northeastern italy and in western slovenia abstract the source parameters of the major events of a swarm and of two seismic sequences occurred in the friuli area northeastern italy and in western slovenia were estimated the claut swarm c96 occurred since the end of january to june 1996 with a md 4 3 major shock and it appears composed of three sub sequences the two sequences are the kobarid sequence k98 started on april 12 1998 with a md 5 6 mainshock and the m te sernio s02 sequence caused by the february 14 2002 earthquake md 4 9 acceleration and velocity data recorded by the local seismic network of the istituto nazionale di oceanografia e di geofisica sperimenale ogs and corrected for attenuation were employed to estimate seismic moments and radiated energies source dimensions were inferred from the computed corner frequencies and the stress release was estimated from the brune stress drop the apparent stress and the rms stress drop on the whole seismic moments range from 1 7 1012 to 1 1 1017 n m and radiated energies are in the range 106 1013 j brune stress drops are scattered and do not show any evidence of a self similarity breakdown for sources down to 130 m radius the radiated seismic energy scales as a function of seismic moment with a slope of the scaling relation that decreases for increasing seismic moments the mechanism of stress release was analyzed by computing the parameter of zuniga zuniga r 1993 frictional overshoot and partial stress drop which one bull seismol soc am 83 939 944 the k98 and s02 sequences are characterized by a wide range of the parameter with stress drop mechanism varying from partial locking to overshoot cases the values of the c96 swarm are more homogeneous and close to the orowan s condition the radiated seismic energy and the ratio of stress drop between mainshock and aftershocks appear different among the analyzed cases we therefore investigated the relationship between the stress parameters of the main shock and the energy radiated by the aftershock sequences for this purpose we also estimated the source parameters of two other sequences occurred in the area with mainshocks of md 4 1 and 5 1 respectively we found a positive correlation between the brune stress drop of the mainshock and the ratio between the radiated energy of the mainshock and the summation of the energies radiated by the aftershocks

the yellowstone snake river plain seismic profiling experiment crustal structure of the eastern snake river plain seismic refraction profiles recorded along the eastern snake river plain esrp in southeastern idaho during the 1978 yellowstone snake river plain cooperative seismic profiling experiment are interpreted to infer the crustal velocity and attenuation q 1 structure of the esrp travel time and synthetic seismogram modeling of a 250 km reversed refraction profile as well as a 100 km detailed profile indicate that the crust of the esrp is highly anomalous approximately 3 to 6 km of volcanic rocks with some interbedded sediments overlie an upper crustal layer compressional velocity approx 6 1 km s which thins southwestward along the esrp from a thickness of 10 km near island park caldera to 2 to 3 km beneath the central and southwestern portions of the esrp an intermediate velocity approx 6 5 km s layer extends from approx 10 to approx 20 km depth a thick approx 22 km lower crust of compressional velocity 6 8 km s a total crustall thickness of approx 42 km and a p sub n velocity of approx 7 9 km s is observed in the esrp similar to the western snake river plain and the rocky mountains provinces high attenuation is evident on the amplitude corrected seismic data due to low q values in the volcanic rocks q sub p more 20 to 200 and throughout the crust q sub p 160 to 300 based on these characteristics of the crustal structure and volcanic age progression data it is suggested that the esrp has resulted from an intensitive period of intrusion of mantle derived basaltic magma into the upper crust generating explosive silicic volcanism and associated regional uplift and caldera collapse this activity began about 15 m y ago in southwestern idaho and has migrated northeast to its present position at yellowstone subsequent cooling of the intruded upper crust results in the 6 5 km s velocity intermediate layer crustal subsidence and periodic basaltic volcanism as represented by the esrp complete the sequence of crustal evolution less

felsenmeer persistence under non erosive ice in the torngat and kaumajet mountains quebec and labrador as determined by soil weathering and cosmogenic nuclide exposure dating soil analyses and terrestrial cosmogenic nuclide exposure dating are combined and a conceptual model proposed to explain altitudinal weathering contrasts in high latitude highlands we show that summits in the torngat and kaumajet mountains were covered by ice during the last glacial maximum and that their felsenmeer cover probably survived multiple glaciation events for similar lithologies soils on felsenmeer covered summits are signigicantly more weathered than those below the felsenmeer limit displaying higher concentrations of crystalline iron amorphous aluminium and silicium extracted with oxalate secondary minerals such as gibbsite and kaolinite occur in felsenmeer soils whereas those formed in till lacked these secondary minerals 10be and 26al exposure ages for nine of ten samples from high elevation tors and autochthonous felsenmeer blocks range from 73 6 to 157 15 ka by contrast ages of 11 4 1 0 and 11 7 1 0 ka are measured for bedrock in the much lower saglek zone indicating extensive 3 m glacial erosion of this zone during late wisconsinan glaciation 26al 10be ratios demonstrate that exposure of the high elevation surfaces was interrupted during at least one cosmic ray shielding event by either ice or till cover in either case late wisconsinan glaciers could not have extensively eroded these surfaces five erratics dated above the saglek zone including one in the felsenmeer zone have exposure ages ranging from 11 6 1 0 to 13 6 0 7 ka this indicates that valley and high elevation ice persisted through the younger dryas chron and provides further evidence that the highlands were not nunataks during the late wisconsinan period

cutting of the european continental lithosphere plasticity theory applied to the present alpine collision presently active european alpine collision has a history of more than 100 myr convergence we investigate the collisional contact problem of an apparently rigid african promontory currently the italy adria block iab steadily penetrating at 1 cm yr over at least the past 45 myr into the deformable european plate we assume that neither continental subduction nor delamination occurs presently in the 300 km wide contact zone enabling use of the indenter indentee approach a key parameter is the aspect ratio h a defined by the width of the deformable foreland over the width of the indenter itself this parameter controls the activation of two fundamentally different modes of deformation 1 classical indentation mode for h a 4 4 described by previous authors and having effect only in a portion of the deformable plate in the vicinity of the indenter and 2 cutting mode for h a 4 4 giving plane strain longitudinal splitting of the entire deformable plate and plastic separation of the two halves we use a matrix operator method to solve for slip lines in the mixed boundary value problem obliquity velocity friction stress of the european alpine case implications are as follows 1 plane stress vertical lithospheric thickening is the first indentation mode of continental collision and 2 for the present ratio of h a 3 deformation is in the cutting mode and slow plane strain intraplate extension rifting is predicted this mode explains the intraplate stress field obtained from borehole and earthquake data considering that the paleoindenter probably has been larger than the iab it is inferred that h a has been below 4 4 since at least the end of the eocene and that consequently the intraplate graben system lower rhine rhine bresse limagne is due to the cutting of the european plate by alpine collision

properties and genesis of a soil and the underlying gibbsite bearing saprolite cape breton island canada brownish yellow saprolite derived from granite gneiss is exposed beneath 1 2 m of reddish brown till along a roadcut in the cape breton highlands the strongly acid soil is similar to other podzolic soils of the region except for the presence of gibbsite in the silt and clay fractions in the saprolite feldspar and biotite have weathered to poorly crystalline kaolinite gibbsite and a minor component of iron oxide the poorly crystalline kaolinite does not occur in the overlying till the evidence presented is consistent with the view that the area was covered either by cold based or by stagnant warm based glaciers that eroded the pre quaternary surface only slightly and deposited a thin discontinuous veneer of till derived mainly from local bedrock and saprolite weathering products from the saprolite are probably incorporated commonly in tills of the area during the formation of soils in these tills the poorly crystalline kaolinite and most of the gibbsite are either transformed to other minerals

paleosols and holocene soils occurring over the north mountain basalt in nova scotia and grand manan island canada abstract on the northwest coast of nova scotia the north mountain basalt makes a major contribution to local lithology on this formation there are occurrences of pre wisconsinan saprolite which has survived one or more periods of glaciation holocene weathering has produced brunisolic soils inceptisols on the saprolite and a variety of soil types on the till covering this formation the clay sized fraction of the pre wisconsinan saprolite is almost wholly smectitic and weathering has only slightly changed its composition although the till formed over the basalt contains only basaltic fragments the clay sized fractions have a variety of mica type clay minerals which are not significantly dissimilar to those developed in a soil profile occurring in till over neighbouring granite

chemical weathering studies in relation to geomorphological research in southeastern canada abstract although chemical weathering provides fundamental information relevant to geomorphology the subject has been overlooked during the 20th century in canada this paper provides an overview of the current state of canadian research on chemical weathering in southeastern canada and takes into account three spatial and temporal contexts 1 the formation of bedrock morphology by chemical weathering 2 occurrences characteristics and age of saprolites and 3 contemporary chemical denudation rates long term geomorphological evolution of southeastern canadian landscapes shows that chemical weathering has played an important role an example is taken from the laurentide region of the canadian shield north of montreal quebec the present topography resulted from the stripping of the former weathering mantle and from the probable subsequent modification of the weathering front first by the action of hillslope processes and rivers and then by glaciers before and during plio pleistocene times the present landscape reflects the timing of the formation of erosion surfaces and of the stripping of the paleozoic cover rocks and exposure of the shield since the late seventies several isolated occurrences of saprolite soil profiles have been discovered in eastern canada and prompted a renewal of the study of these materials about the cenozoic evolution of these regions one of the problems in this field of research is the dating of saprolites and their inclusion in a chronostratigraphic framework along with the other cenozoic surficial deposits and landforms because of the multiple factors involved in the development of secondary minerals in saprolites during the course of weathering it is preferable to distinguish the dating of saprolites from the study of their mineralogical and geochemical evolution fortunately several new techniques are becoming available for the absolute dating of surficial deposits and saprolites including the use of cosmogenic radionuclides saprolites provide a strong potential field of research for our understanding of the geological evolution of eastern canada during the cenozoic contemporary weathering and erosion rates are fields of research that have gained increasing interest recently since modeling landscape geochemical response can be applied to various environmental stress situations such as acidification by rain and forest harvesting rock type may be the main factor explaining the large differences between watersheds in fact variability of cation removal in the temperate zone is probably most closely related to flow paths of water investigations at different scales from entire watersheds to slopes to individual pedons highlight the problem in the catamaran brook watershed new brunswick water chemistry is explained by a mix of groundwater and soil solution from the horizons at the base of the floodplain soils geochemical mass balances based on net outputs give little information on the weathering reactions of primary minerals the weathering products or on the nature of the weathering processes that provide the dissolved load of streams mineralogic and petrographic analysis of selected soil pedons are necessary to determine weathering reactions and their role as sources or sinks for bases silica aluminum and iron in the various compartments through which water percolates before it reaches the stream

stress triggering in thrust and subduction earthquakes and stress interaction between the southern san andreas and nearby thrust and strike slip faults 1 we argue that key features of thrust earthquake triggering inhibition and clustering can be explained by coulomb stress changes which we illustrate by a suite of representative models and by detailed examples whereas slip on surface cutting thrust faults drops the stress in most of the adjacent crust slip on blind thrust faults increases the stress on some nearby zones particularly above the source fault blind thrusts can thus trigger slip on secondary faults at shallow depth and typically produce broadly distributed aftershocks short thrust ruptures are particularly efficient at triggering earthquakes of similar size on adjacent thrust faults we calculate that during a progressive thrust sequence in central california the 1983 mw 6 7 coalinga earthquake brought the subsequent 1983 mw 6 0 nunez and 1985 mw 6 0 kettleman hills ruptures 10 bars and 1 bar closer to coulomb failure the idealized stress change calculations also reconcile the distribution of seismicity accompanying large subduction events in agreement with findings of prior investigations subduction zone ruptures are calculated to promote normal faulting events in the outer rise and to promote thrust faulting events on the periphery of the seismic rupture and its downdip extension these features are evident in aftershocks of the 1957 mw 9 1 aleutian and other large subduction earthquakes we further examine stress changes on the rupture surface imparted by the 1960 mw 9 5 and 1995 mw 8 1 chile earthquakes for which detailed slip models are available calculated coulomb stress increases of 2 20 bars correspond closely to sites of aftershocks and postseismic slip whereas aftershocks are absent where the stress drops by more than 10 bars we also argue that slip on major strike slip systems modulates the stress acting on nearby thrust and strike slip faults we calculate that the 1857 mw 7 9 fort tejon earthquake on the san andreas fault and subsequent interseismic slip brought the coalinga fault 1 bar closer to failure but inhibited failure elsewhere on the coast ranges thrust faults the 1857 earthquake also promoted failure on the white wolf reverse fault by 8 bars which ruptured in the 1952 mw 7 3 kern county shock but inhibited slip on the left lateral garlock fault which has not ruptured since 1857 we thus contend that stress transfer exerts a control on the seismicity of thrust faults across a broad spectrum of spatial and temporal scales

a granulometry and secondary mineral fingerprint of chemical weathering in periglacial landscapes and its application to blockfield origins abstract a review of published literature was undertaken to determine if there was a fingerprint of chemical weathering in regoliths subjected to periglacial conditions during their formation if present this fingerprint would be applied to the question of when blockfields in periglacial landscapes were initiated these blocky diamicts are usually considered to represent remnants of regoliths that were chemically weathered under a warm neogene climate and therefore indicate surfaces that have undergone only a few metres to a few 10s of metres of erosion during the quaternary based on a comparison of clay and silt abundances and secondary mineral assemblages from blockfields other regoliths in periglacial settings and regoliths from non periglacial settings a fingerprint of chemical weathering in periglacial landscapes was identified a mobile regolith origin under at least seasonal periglacial conditions is indicated where clay 0 5 silt 8 across a sample batch this contrasts with a mobile regolith origin under non periglacial conditions which is indicated where clay 0 5 silt 6 across a sample batch with clay 0 5 silt 8 in at least one sample a range of secondary minerals which frequently includes interstratified minerals and indicates high local variability in leaching conditions is also commonly present in regoliths exposed to periglacial conditions during their formation clay silt ratios display a threshold response to temperature related to the freezing point of water but there is little response to precipitation or regolith residence time lithology controls clay and silt abundances which increase from felsic through intermediate to mafic compositions but does not control clay silt ratios use of a sedigraph or coulter counter to determine regolith granulometry systematically indicates lower clay abundances and intra site variability than use of a pipette or hydrometer in contrast to clay silt ratios secondary mineral assemblages vary according to regolith residence time temperature and or precipitation a microsystems model is invoked as a conceptual framework in which to interpret the concurrent formation of the observed secondary mineral ranges according to the fingerprint of chemical weathering in periglacial landscapes there is generally no evidence of blockfield origins under warm neogene climates nearly all blockfields appear to be a product of quaternary physical and chemical weathering a more dominant role for periglacial processes in further bevelling elevated low relief non glacial surface remnants in otherwise glacially eroded landscapes is therefore indicated

structure of the lithosphere beneath the eastern alps southern sector of the transalp transect abstract the interpretation of the seismic vibroseis and explosive transalp profiles has examined the upper crustal structures according to the near surface geological evidences and reconstructions which were extrapolated to depth only the southern sector of the transalp transect has been discussed in details but its relationship with the whole explored chain has been considered as well the seismic images indicate that pre collision and deep collision structures of the alps are not easily recognizable conversely good records of the neo alpine to present architecture were provided by the seismic sections two general interpretation models crocodile and extrusion have been sketched by the transalp working group 2002 both illustrate the continental collision producing strong mechanical interaction of the facing european and african margins as documented by giant lithosphere wedging processes arguments consistent with the extrusion model and with the indentation of adriatic southalpine lithosphere underneath the tauern window tw are according to the previous dss reconstructions the bouguer anomalies and the receiver functions seismological data the european moho descends regularly attaining a zone south of the periadriatic lineament pl the moho boundary and its geometry appear to be rather convincing from images of the seismic profile the tauern window intense uplift and exhumation is coherent with the strong compression regime which acted at depth thus originating the upward and lateral displacement of the mobile and ductile penninic masses according to the extrusion model the indentation of the penninic mobile masses within the colder and more rigid adriatic crust cannot be easily sustained wedging of the adriatic stiffened lower crust under high stresses and into the weaker penninic domain can be a more suitable hypothesis furthermore the intrusion of the european penninic crustal wedge underneath the dolomites upper crust is not supported by any significant uplifting of the dolomites the total average uplift of the dolomites during the neogene appears to be 6 7 times smaller than that recognized in the tw markedly the northward dip of the pl reaching a depth of approximately 20 km is proposed in our interpretation finally the adriatic upper crustal evolution points to the late post collision change in the tectonic grow up of the eastern alps orogenic chain the tectonic accretion of the northern frontal zone of the eastern and central alps was interrupted from the late miocene serravallian tortonian onward as documented by the molasse basin evolution on the contrary the structural nucleation along the s vergent tectonic belt of the eastern southern alps montello friuli thrust belt severely continued during the messinian and the plio pleistocene this structural evolution can be considered to be consistent with the deep under thrusting and wedge indentation of the adriatic lithosphere underneath the southern side of the eastern alps thrust and fold belt similarly the significance of the magmatic activity for the construction of the southern alps crust and for its mechanical and geological differentiation which qualified the evolution of the thrust and fold belt is highlighted starting with the permian triassic magmatism and progressing with the paleogene occurrences along the periadriatic lineament and in the venetian magmatic province lessini euganei hills

neotectonic extrusion of the eastern alps constraints from u th dating of tectonically damaged speleothems we suggest that the salzachtal ennstal mariazell puchberg semp fault a major strike slip system in the european alps is active it has accommodated lateral extrusion of the central part of the eastern alps toward the pannonian basin the main tectonic activity of this fault dates back to oligocene and miocene time but until now it was largely unknown whether the fault was still active we present here the first field evidence of neotectonic activity from a cave in the hochschwab karst massif styria austria that intersects a segment of the semp fault zone damaged speleothems in this cave include scratched flowstone a hitherto undescribed feature massive flowstone disrupted by a fault and ruptured flowstone the superposition of younger flowstone layers allows constraining the time frame of the tectonic events using u th dating the youngest flowstone of the pre damage generation is ca 118 ka end of the last interglacial and the oldest post event layer is ca 9 ka early holocene the tectonic event bracketed by these layers coincided with a growth hiatus during the last glacial period consistent with the high alpine setting of the cave geologic evidence precludes deformation mechanisms other than tectonic these new data are consistent with vectors of continuous global positioning system measurements as well as instrumental seismicity data and collectively suggest that the semp is an active fault and that lateral extrusion of the eastern alps is ongoing

static stress drop as determined from geodetic strain rates and statistical seismicity accepted for publication in journal of geophysical researches copyright 2010 american geophysical union

canadian geomorphology 2000 geomorphology has a distinguished history in canada as old as the country itself initially the science of geomorphology of canada drew on rich british and french scientific traditions but later it developed its own character strongly influenced by the richness and diversity of the canadian landscape the strong imprint of glaciation and the importance of periglacial processes permafrost and sea ice canada is the second largest country in the world its coastline is longer and more varied than that of any other country nearly one third of canada is underlain by permafrost some up to 700 m thick the country s physiography ranges from nearly flat coastal and interior plains to the glacierised mountains of baffin and ellesmere islands british columbia and the yukon its climate and vegetation are equally diverse ranging from the cold semiarid tundra of the high arctic to the temperate rainforest of the pacific coast given this diversity it is not surprising that canada is active in many areas of geomorphic research an incredible spectrum of landforms and geomorphic processes has fostered world class research in canada both by canadians and by scientists from other countries much of this research is field based and empirical rooted in field observation in recent decades however there have been important advances in inductive laboratory and

late cenozoic deep weathering patterns on the fennoscandian shield in northern finland a window on ice sheet bed conditions at the onset of northern hemisphere glaciation abstract the nature of the regolith that existed on the shields of the northern hemisphere at the onset of ice sheet glaciation is poorly constrained in this paper we provide the first detailed account of an exceptionally preserved deeply weathered late neogene landscape in the ice sheet divide zone in northern finland we mine data sets of drilling and pitting records gathered by the geological survey of finland to reconstruct regional preglacial deep weathering patterns within a gis framework using a large geochemical data set we give standardised descriptions of saprolite geochemistry using a variant of the weathering index of parker wip as a proxy to assess the intensity of weathering we also focus on mineral prospects and mines with dense pit and borehole data coverage in order to identify links between geology topography and weathering geology is closely linked to topography on the preglacial shield landscape of northern finland and both factors influence weathering patterns upstanding resistant granulite granite gabbro metabasalt and quartzite rocks were associated with fresh rock outcrops including tors or with thin fines values above 3000 and 4000 beneath valley floors developed along mineralised shear and fracture zones weathering penetrated locally to depths of 50 m and included intensely weathered kaolinitic clays with wip fines values below 1000 late neogene weathering profiles were varied in character tripartite clay gruss saprock profiles occur only in limited areas bipartite gruss saprock profiles were widespread with saprock thicknesses of 10 m weathering profiles included two discontinuities in texture materials and resistance to erosion between saprolite and saprock and between saprock and rock limited core recovery when drilling below the soil base in mixed rocks of the tana belt indicates that weathering locally penetrated deep below upper fresh rock layers such deep seated weathered bands in rock represent a third set of discontinuities incipient weathering and supergene mineralisation also extended to depths of 100 m in mineralised fracture zones the thin weathering crusts found extensively beneath till may represent types of early or middle pleistocene palaeosols we confirm that glacial erosion has been very limited

present day lithospheric strength of the eastern alps and its relationship to neotectonics 1 we calculate the present day lithospheric strength of the eastern alps along the new reflection seismic profile transalp to examine vertical and lateral strength variations and their implications on neotectonic activity of the eastern alps the large scale geometry of the eastern alps and the spatial distribution of upper and lower crustal layers and the lithospheric mantle is constrained by the deep seismic line two rheological models coupled to a kinematic thermal model that accounts for the thermal evolution of the eastern alps for the last 30 myr are investigated for the present day lithospheric configuration in the eastern alps models with strong model a and weak model b crustal rheologies predict the european and the adriatic plates to be stronger than the central zone of the orogen comprising the region between the inntal fault and the periadriatic fault model a is characterized by a brittle ductile boundary between 14 and 9 km depth and strong coupling of the mechanically strong lower crust to the upper mantle whereas model b suggests the presence of a thick decoupling zone between the upper crust and the upper mantle and a shallower brittle ductile boundary 7 10 km of these end member scenarios model a is in better agreement with neotectonic data including seismicity down to the upper lower crust boundary within the adriatic plate uplift of the central zone of the eastern alps and the southern alps and eastward escape of fault bound blocks such deformation pattern is best explained by lateral extrusion upon north south compression supporting a strong weak strong configuration of tectonic units along the transalp line

on the causes and modes of exhumation and lateral growth of the alps 1 a compilation of the apatite and zircon fission track ages of the alpine chain points to markedly different patterns of cooling and exhumation of the eastern alps compared to the central and western alps the site of exhumation and shortening in the western alps migrated outward whereas it was more stationary in the eastern alps where it created a narrower metamorphic belt a correlation of these observations to the deep structure of the orogen suggests that north directed lower crustal wedging induces northward propagation of the deformation and exhumation front in the middle and upper crust of the central and western alps the absence of such lower crustal wedges in the eastern alps does not induce a similar shift of deformation but rather a long term localization of shortening and exhumation in one and the same area namely the axial zone of the orogen a critical review of the temporal correlations between inferred changes in the erosional efficiency of the alps and tectonic phases points to a negative correlation and hence no erosional control on the shifts of the deformation front of the alps therefore we conclude that changes in the deep structure and rheology of the orogen instead of changes in its erosional efficiency exerted the prime control on the lateral growth of the alps

characteristics and significance of two pre late wisconsinan weathering profiles adirondacks usa and miramichi highlands canada abstract the properties of two weathering profiles developed from granitic rocks and covered by deposits of wisconsinan age were studied in order to characterize saprolites and non saprolite residuum of the glaciated area of northeastern north america the warrensburg profile adirondacks new york is more than 9 m thick and formed on a hornblende granitic gneiss total chemical analysis of the sandy saprolite shows slight losses compared to bedrock kaolinite is the main weathering product in the

glacier shrinkage and modeled uplift of the alps 1 present day glacier reduction in the alps estimated from glacier inventories and induced viscoelastic response of a stratified earth s model is responsible for sizable uplift rates patches of 0 4 0 5 mm yr due to ice mass loss of largest ice complexes overprint a characteristic area of slower uplift of 0 1 0 2 mm yr signature of the phenomenon in the whole alpine chain viscous stress relaxation in the lower crust due to glacier mass loss after the end of the little ice age is expected to produce uplift rates of 0 32 mm yr leading to a total viscoelastic response up to 0 8 mm yr our predictions in the western alps show that viscoelastic response to present day glacier shrinkage forms a substantial fraction half of the observed uplift data attempts to constrain the contributions arising from active alpine tectonics and drainage must account for this uplift signal citation barletta v r c ferrari g diolaiuti t carnielli r sabadini and c smiraglia 2006 glacier shrinkage and modeled uplift of the alps geophys res lett 33 l14307 doi 10 1029 2006gl026490

comment on rosenberg and garcia estimating displacement along the brenner fault and orogen parallel extension in the eastern alps int j earth sci geol rundsch 2011 100 1129 1145 the western end of the tauern window is marked by what we refer to as the brenner normal fault zone the brenner fault since the late eighties is known as a textbook example of a normal fault already in 1934 dunner proposed west directed normal faulting related to updoming of the footwall i e the tauern window these earlier publications e g schmidegg 1953 mainly focussed on a brittle normal fault known as silltal fault that represents a northern segment of the brenner normal fault zone behrmann 1988 and selverstone 1988 were the first to also describe ductile components of normal faulting in an area further south referred to as sterzing steinach mylonite zone behrmann or brenner line selverstone in 1997 fugenschuh et al presented a two stage model for the evolution of the brenner normal fault zone thereby ductile normal faulting was restricted to an area between sterzing and matrei during stage 1 referred to as brenner normal fault s str in this contribution while brittle faulting during stage 2 not only overprinted the earlier mylonites of the brenner line s str but extended further north into the entirely brittle silltal fault this model involved coeval n s compression and e w extension during stage 1 the published calculated total amounts of related e w extension derived from metamorphic data and distinct exhumation histories in footwall and hanging wall and from the estimated dip of the overall fault zone varied significantly between 10 and 20 km e g behrmann 1988 and up to 70 km e g fugenschuh et al 1997 the contribution of exhumation by erosion as a consequence of coeval n s compression has never been explicitly considered and calculated so far

weathering characteristics of arctic islands in northern norway the arctic islands of the lofoten vesteralen archipelago in northern norway have a wide distribution of weathered land surfaces commonly located above 250 m with several apparent similarities in order to investigate the characteristics of deep weathering in this region northern langoya and hadseloya were chosen for in depth analyses eight weathering profiles were excavated from various surfaces and the stratigraphies were logged in detail material was collected throughout the weathering horizons and all samples were subsequently analysed for clay mineralogy 40 000 years of subaerial conditions considering the steady surface erosion this figure should be viewed as an absolute minimum age estimate mapping of the superficial sediments and geomorphological features of the study areas has revealed several common morphological features which indicate dominance of glacial and periglacial processes in the areas lying below the lower boundary of blockfields c 250 m the weathering mantles are not a periglacial end product but rather a relict tertiary landform that were modulated by permafrost processes as well as biological processes at later stages the regolith cover constrain the vertical extension of warmbased quaternary ice sheets challenging the notion of a parabolic ice mass consuming every mountain top of lofoten and vesteralen

the database of individual seismogenic sources diss version 3 summarizing 20 years of research on italy s earthquake geology abstract this paper describes the main characteristics the evolution and the structure of the database of individual seismogenic sources diss and particularly of its release of early 2007 the database contains the results of the investigations of the active tectonics in italy during the past 20 years the first two sections of this paper document the recent evolution in mapping and archiving italian active fault data in relation to important achievements in the understanding of italian tectonics some of which were spurred by significant earthquakes the central sections describe the current structure of the database the reasons for its assumptions and data categories its current contents its evolution through several years of improvements the last section describes how the current contents of the database correspond with the existing strain and stress data available from focal mechanism borehole breakout and gps data for the whole of italy the database supplies a fresh and unified view of active and seismogenic processes in italy by building on basic physical constraints concerning rates of crustal deformation on the continuity of deformation belts and on the spatial relationships between adjacent faults both at the surface and at depth

new paleocene eocene paleomagnetic results from the foreland of the southern alps confirm decoupling of stable adria from the african plate abstract from the undeformed foreland of the southern alps paleocene through early miocene rocks mostly biostratigraphically well dated sediments with sub horizontal bed attitude were collected for a paleomagnetic study from 23 geographically distributed localities the samples were subjected to standard paleomagnetic measurements and evaluation while the miocene samples are unstable most of the older localities yielded statistically well defined paleomagnetic directions these are interpreted as primary for the compact marls supported by positive between locality tilt and reversal tests this large group of localities is characterized by ccw rotated declinations with respect to the present north combined with paleomagnetic directions of corresponding age from stable istria these allow definition of the apw for stable adria for the 61 6 33 9 ma interval which is significantly displaced from the coeval segment of the african apw due to the decoupling of the former to the latter by a moderate ccw rotation this post eocene final separation exact age is not constrained directly but estimated as end of miocene was preceded by a small cw rotation of adria with respect to africa suggested by unchanged orientation of the former across the cretaceous paleocene boundary while the latter continued its ccw rotation

young uplift in the non glaciated parts of the eastern alps abstract we report the first incision rates derived from burial ages of cave sediments from the mur river catchment at the eastern margin of the eastern alps at the transition zone between the alpine orogen and the pannonian basin this river passes through the paleozoic of graz a region of karstifiable rocks called the central styrian karst this river dissects the study area in a north south direction and has left behind an abundance of caves these caves can be grouped into several distinct levels according to their elevation above the present fluvial base level age estimates of abandoned cave levels are constrained by dating fluvial sediments washed into caves during the waning stages of speleogenesis with the terrestrial cosmogenic nuclide method these ages and the elevations of the cave levels relative to the current valley floor are used to infer a very complex history of 4 million years of water table position influenced by the entrenchment and aggradation of the mur river we observe rather low rates of bedrock incision over the last 4 ma in the order of 0 1 mm y with an e folding decrease in this trend to lower rates at younger times we relate this incision history to a tectonic setting where an increase of drainage area of the mur river due to stream piracy in late miocene to pliocene times is linked to surface uplift the later decrease in valley lowering rates is attributed to the rise of the base level related to aggradation of sediments within the valley sediment transport through the valley from the upstream section of the mur river limited the erosional potential of the river to a transport limited state at the later stages of the incision history

rounded cobbles that have not travelled far incorporation of corestones from saprolites in the south mountain area of southern nova scotia canada saprolitic palaeosurfaces occur at several localities on the granitoid rocks of the south mountain batholith of nova scotia there are three ages of saprolites within the study area pre pleistocene pre triassic and pre carboniferous within these in place weathered horizons there are remnant ellipsoidal blocks of unweathered granitoid referred to as corestones these corestones are isolated rounded pods of relatively unweathered material surrounded by rotted granitoid saprolitic material the weathered material which surrounds these corestones is poorly consolidated and easily eroded the erosion of these horizons produces a lag deposit that contains many rounded corestones which can be incorporated into subsequent sedimentary units the rounded boulders cobbles and pebbles of granite within many of the pleistocene glacial deposits in southern nova scotia are probably related to the incorporation of these saprolite related structures given the locally derived within 400 m of the source nature of the tills the presence of saprolites at unconformities of various ages on the south mountain granitoid rocks suggests that incorporation of saprolitic material probably occurred along a number of palaeosurfaces in the past the recognition of this process has implications for the interpretation of rounded granite clast conglomerates and quartz rich sandstones of various ages within the stratigraphic record of eastern canada similar palaeosurfaces elsewhere in the world also have related saprolite derived sedimentary rocks associated with them in summary well rounded spherical pebbles cobbles and boulders of granitoid material incorporated in sedimentary strata need not have travelled far from source nor are they necessarily recycled from older conglomerates

weathering patterns in high latitude regolith 1 large areas distributed on the earth s surface are covered by regolith an unconsolidated heterogeneous material overlying bedrock in high latitude areas most of the land surface has been reworked and eroded by both glacial and fluvial processes leaving only remnants of formerly extensive regolith covers in an effort to further the understanding of weathering patterns and processes in old regolith covers a comprehensive study of localities spread across norway was carried out on the basis of the distribution of minerals and elements within regolith as well as its internal structure and geomorphologic setting we ascertained that it was formed in situ and originated in pre quaternary times there are similarities between the study sites with respect to regolith thickness zonation and composition the chemical index of alteration cia and the weathering index of parker wip suggests that the degree of chemical weathering in the regolith is advanced compared to the parental bedrock with a maximum change of over 80 which indicates a substantial increase in the proportion of secondary versus primary minerals mineral analysis identified kaolinite and gibbsite which are considered indicative of advanced weathering and therefore support this observation on the basis of statistical relationships between different grain size fractions 125 m we observed a consistent pattern which revealed that physical weathering becomes progressively less important in the production of grains smaller than 32 m on the basis of this finding we infer that chemical weathering progressively dominates the production of fine silt very fine silt and clay whereas physical weathering primarily controls the production of grain size fractions larger than 32 m this particular pattern is suggested to be an intrinsic feature in the formation of weathered high latitude regolith

forecasting the evolution of seismicity in southern california animations built on earthquake stress transfer 1 we develop a forecast model to reproduce the distribution of main shocks aftershocks and surrounding seismicity observed during 1986 2003 in a 300 310 km area centered on the 1992 m 7 3 landers earthquake to parse the catalog into frames with equal numbers of aftershocks we animate seismicity in log time increments that lengthen after each main shock this reveals aftershock zone migration expansion and densification we implement a rate state algorithm that incorporates the static stress transferred by each m 6 shock and then evolves coulomb stress changes amplify the background seismicity so small stress changes produce large changes in seismicity rate in areas of high background seismicity similarly seismicity rate declines in the stress shadows are evident only in areas with previously high seismicity rates thus a key constituent of the model is the background seismicity rate which we smooth from 1981 to 1986 seismicity the mean correlation coefficient between observed and predicted m 1 4 shocks the minimum magnitude of completeness is 0 52 for 1986 2003 and 0 63 for 1992 2003 a control standard aftershock model yields 0 54 and 0 52 for the same periods four m 6 0 shocks struck during the test period three are located at sites where the expected seismicity rate falls above the 92 percentile and one is located above the 75 percentile the model thus reproduces much but certainly not all of the observed spatial and temporal seismicity from which we infer that the decaying effect of stress transferred by successive main shocks influences seismicity for decades finally we offer a m 5 earthquake forecast for 2005 2015 assigning probabilities to 324 10 10 km cells

reviewing pre transalp dss models abstract the interpretation of dss deep seismic soundings profiles in central and eastern alps is recalled in the paper and the models of the lower crust and moho proposed several years ago are compared to the results of the transalp seismic reflection profile this evaluation highlights a good agreement as far as the geometry of the deep crustal structure is concerned therefore the reliability of the interpretative models previously exclusively based on dss profiles becomes improved the deep structure beneath the whole alpine range is examined reconsidering the map of the moho boundary and the structural model already proposed for the central eastern sector five main interpretative transects are put side by side starting from the western alps and moving eastwards to the swiss lombardian central alps european geotraverse to the cross section from southern bavaria to the euganei hills to the transalp profile and finally to the easternmost profile available so far southern bavaria trieste the comparison outlines lateral variations of the deep crustal structure as well as a sharp contrast between the adria and the european lower crust and moho the transition from the adria plate to the dinaric domain remains up to now undefined

active tectonics of the adriatic region from gps and earthquake slip vectors 1 to investigate the kinematics of the adriatic region we integrate continuous and episodic gps measurements with mw 4 5 earthquake slip vectors selected from the regional centroid moment tensor catalogue coherent motion of gps sites in the po valley in apulia and in the hyblean plateau allows us to estimate geodetically constrained angular velocities for these regions the predictions of the gps inferred angular velocities are compared with the earthquake slip vectors showing that the seismically expressed deformation at the microplate boundaries is consistent with the observed geodetic motion the remarkable consistency between geodetic seismological and geological evidence of active tectonics suggests that active deformation in the central adriatic is controlled by the relative motion between the adria and apulia microplates the microplates angular rotation rates are then compared with the rotation rates calculated with a simple block model supporting the hypotheses 1 that apulia forms a single microplate with the ionian sea and possibly with the hyblean region and 2 that adria and apulia rotate in such a way as to accommodate the eurasia nubia relative motion we suggest that the present day microplate configuration follows a recent fragmentation of the adriatic promontory that during the neogene rigidly transferred the africa motion to the orogenic belts that now surround the adriatic region

temperatures heat flux and frictional stress near major thrust faults we examine the two dimensional advective and conductive transport of heat in a region of thrust faulting both simple theoretical considerations and numerical experiments show that the steady state temperatures near the fault are reduced by a divisor s 1 b z vsin below what they would be with the same heat sources but in the absence of advection in this expression z is the depth to the fault v is the slip rate is the component of the dip of the fault in the direction of underthrusting is thermal diffusivity and b is a dimensionless factor that is essentially equal to one for most forms of heating initial changes in temperatures near the fault are given by t z t t z 0 12vsin t z 0 z these simple formulae are successful because of the neglible influence of lateral conduction of heat at least for slip rates of a few mm yr or more two time constants govern the transition from the initial change in temperature to steady state t1 u v where u is the distance along the fault in the direction of underthrusting from the surface to the depth in question and t2 z 2 2 where z is the depth to the fault when elapsed times exceed the sum of these two time constants temperatures differ from their steady state values by only about 10 percent the numerical experiments indicate that the simple formulae are sufficiently accurate that sophisticiated numerical modeling of temperatures in specific regions is unwarranted putain an application of these simple formulae to measurements of conductive heat flow at island arcs implies that shear stresses at island arcs approach 100 mpa and are greater than 30 mpa calculations of temperatures appropriate for the himalaya suggest that shear stresses of 100 mpa on the main central thrust probably are required to account for the tertiary granites of the region if melting took place after slip began on the thrust similarly the cut off in seismicity at a depth of about 15 km in the himalaya if due to temperatures exceeding 350 to 450 c implies a deviatoric stress close to 100 mpa

the adriatic region an independent microplate within the africa eurasia collision zone 1 we use gps measurements and block modeling to investigate the present day deformation of the adriatic region whose kinematics within the nubia eurasia plate boundary zone is not well constrained and remains controversial block modeling allows us to compute rigid plate angular velocities while accounting for elastic strain accumulation along block bounding faults results suggest that the adriatic is a microplate adria and that the southern boundary with the nubia plate and the aegean domain may be located along the apulia escarpment and the kefallinia fault geodetic data alone cannot discriminate between a single block ap or a two blocks gdap description of adria but the gdap model predicts boundary slip rates that are in better agreement with observations from previous studies

paleoweathered surfaces on granitoids of southern nova scotia paleoenvironmental implications of saprolites in addition to minor postglacial weathering effects a complex history of three distinct weathering events has been identified within the granitoids of the south mountain batholith of southwestern

neogene quaternary tectonic stratigraphy of the eastern southern alps ne italy abstract in order to reconstruct the neogene quaternary tectonic stratigraphy of the eastern southern alps the late tortonian lower pleistocene foredeep clastic sequences cropping out in the veneto and friuli piedmont areas have been extensively investigated focusing on the contractional features observed in the frequent conglomerate layers pitted pebbles the eastern southern alps is the result of a typical polyphase tectonic activity initiated in late oligocene characterised by the occurrence of several non coaxial stress regimes based on careful analyses of the pebbles surfaces shape and orientation of the indented features and following a systematic and statistical approach the mean orientation of the maximum compressive stress axis 1 has been obtained for more than 30 sites of measurements along the ca 120 km long investigated piedmont area the affected lithostratigraphic units and the orientation pre versus post tilting of the stereonets density peaks make it possible to recognize four distinct deformational events and characterize them in terms of mean 1 direction and timing late tortonian 1 313 00 late messinian early pliocene 338 04 late pliocene 314 03 and early middle pleistocene 160 03 the tectonic stratigraphy of the eastern southern alps during the last ca 10 ma shows the occurrence of several variations of the stress field characterized by a repeated oscillation of the 1 axis between an nnw sse and nw se directions twist tectonics taking also into account literature data about older deformational events chattian burdigalian and serravallian tortonian we analyse the neogene quaternary tectonic evolution in the frame of the central mediterranean realm and compare it with the convergence direction between the adria africa and europe lithospheric plates we show that compressional directions within the eastern southern alps are basically governed by the remote plate convergence though since late messinian the approaching northern apennines started to play a crucial role within the investigated area alternating short lived phases 1 2 ma of coupling and decoupling along the basal detachment of the apennines accretionary wedge probably caused temporary perturbations of the local stress field and complex accommodation structures in this region of ongoing crustal collision

evolution geochimique superficielle des pyroxenites ignees du mont saint bruno quebec samples were collected in a saprolite and soil profiles derived from the weathering of igneous pyroxenites at mount saint bruno quebec alternation of the disaggregated rock produces small amounts of 2 m material the various minerals present in the pyroxenite augite plagioclases olivine and biotite and their weathering products were separated and analyzed with a microprobe all primary minerals are transformed into smectites identified as beidellites montmorillonites saponites fe mg smectites and transition smectites the microenvironment determines the nature of the secondary minerals

miocene to present major fault linkages through the adriatic indenter and the austroalpine penninic collisional wedge alps of ne italy

present state of tectonic stress of the friuli area eastern southern alps stress orientations are determined for the friuli area from focal mechanisms using the inversion technique of gephart and forsyth 1984 the data consist of 244 fault plane solutions selected for the period 1988 1995 where the data coverage was poor this period was extended to 1978 1996 local magnitude ranges from 2 0 to 4 3 and the depths extend from 4 to 16 km the friuli area is subdivided into five seismotectonic zones on the basis of tectonic characteristics seismic activity and focal mechanisms and for each zone a stress tensor is determined the results show that the active tectonic stress in the friuli area is heterogeneous and conditioned by the complex structural pattern which is characterized by two indented tectonic wedges the western and central parts of the area are mainly affected by a compressional state of stress while in the eastern part a strike slip state of stress prevails the orientation of the principal stresses varies from the western to the eastern part of the area and differences are also noticeable with depth in the central part of the friuli area the maximum compressional stress is n s trending at shallow depths 10 km changing to nw se at deeper levels the maximum compressional stress is nw se oriented in the western part while in the eastern part it is n s oriented

balancing lateral orogenic float of the eastern alps abstract oligocene to miocene post collisional shortening between the adriatic and european plates was compensated by frontal thrusting onto the molasse foreland basin and by contemporaneous lateral wedging of the austroalpine upper plate balancing of the upper plate shortening by horizontal retrodeformation of lateral escaping and extruding wedges of the austroalpine lid enables an evaluation of the total post collisional deformation of the hangingwall plate quantification of the north south shortening and east west extension of the upper plate is derived from displacement data of major faults that dissect the austroalpine wedges indentation of the south alpine unit corresponds to 64 km north south shortening and a minimum of 120 km of east west extension lateral wedging affected the eastern alps east of the giudicarie fault west of the giudicarie fault north south shortening was compensated by 50 to 80 km of backthrusting in the lombardian thrust system of the southern alps the main structures that bound the escaping wedges to the north are the inntal fault system ca 50 km sinistral offset the konigsee lammertal traunsee klt fault 10 km and the salzach ennstal mariazell puchberg semp fault system 60 km these faults as well as a number of minor faults with displacements less than 10 km root in the basal detachment of the alps the thin skinned nature of lateral escape related structures north of the semp line is documented by industry reflection seismic lines crossing the northern calcareous alps nca and the frontal thrust of the eastern alps complex triangle zones with passive roof backthrusts of middle miocene molasse sediments formed in front of the laterally escaping wedges of the northern eastern alps the aim of this paper is a semiquantitative reconstruction of the upper plate of the eastern alps most of the data is published elsewhere

messinian climate change and erosional destruction of the central european alps at the end of the miocene the european alps ceased outward expansion and tectonic uplift and exhumation shifted into the orogen interior this shift is consistent with a change from orogenic construction to orogenic destruction reflecting an increase in the ratio of erosional flux to accretionary flux the coincidence of this change with an increase in sediment yield from the alps suggests a climate driven increase in erosional flux the timing of deformation and sediment release from the southern alps indicates that the tectonic change occurred synchronous with the last phase of the messinian salinity crisis we attribute the increase in erosional flux to a climatic shift to wetter conditions throughout europe likely augmented by the base level fall that occurred during the mediterranean dessication this climate change is represented in the stratigraphic record by the lago mare deposits of the mediterranean salinity crisis

first deep seismic reflection images of the eastern alps reveal giant crustal wedges and transcrustal ramps 1 the alps are considered as a classical example for an orogen created by continental plate collision in this study we present new images obtained from deep seismic reflection profiling in the eastern alps between munich and venice which give rise to examine and revise existing concepts the seismic sections exhibit a prominent bi verging reflection pattern at crustal scale a major ramp like structure outcropping at the inn valley fault can be traced southward over 80 km into the mountain root where relics of the subducted penninic ocean are expected new models of the evolution of the eastern alps show an upper lower crustal decoupling along transcrustal thrust faults with opposite thrust directions of both the european and the adriatic african continents

characteristics of residual and colluvial soils developed on granite and of the associated pre wisconsin landforms in north central new brunswick an area in north central new brunswick of approximately 20 km2 where tors are common was found to be undisrupted by glaciation the soils in this area are developed on grus and appear to be of pr

quaternary evolution of glaciated gneiss terrains pre glacial weathering vs glacial erosion vast areas previously covered by pleistocene ice sheets consist of rugged bedrock dominated terrain of innumerable knolls and lake filled rock basins the cnoc and lochan landscape or landscape of areal scour these landscapes typically form on gneissose or granitic lithologies and are interpreted 1 either to be the result of strong and widespread glacial erosion over numerous glacial cycles or 2 formed by stripping of a saprolitic weathering mantle from an older deeply weathered landscape we analyse bedrock structure erosional landforms and weathering remnants and within the cnoc and lochan gneiss terrain of a rough peneplain in nw scotland and compare this with a geomorphologically similar gneiss terrain in a non glacial arid setting namaqualand south africa we find that the topography of the gneiss landscapes in nw scotland and namaqualand closely follows the old bedrock saprolite contact weathering front the roughness of the weathering front is caused by deep fracture zones providing a highly irregular surface area for weathering to proceed the weathering front represents a significant change in bedrock physical properties glacial erosion and aeolian erosion in namaqualand is an efficient way of stripping saprolite but is far less effective in eroding hard unweathered bedrock significant glacial erosion of hard gneiss probably only occurs beneath palaeo ice streams we conclude that the rough topography of glaciated cnoc and lochan gneiss terrains is formed by a multistage process 1 long term pre glacial chemical weathering forming deep saprolite with an irregular weathering front 2 stripping of weak saprolite by glacial erosion during the first glaciation s resulting in a rough land surface broadly conforming to the pre existing weathering front etch surface 3 further modification of exposed hard bedrock by glacial erosion in most areas glacial erosion is limited but can be significant beneath palaeo ice stream the roughness of glaciated gneiss terrains is crucial for modelling of the glacial dynamics of present day ice sheets this roughness is shown here to depend on the intensity of pre glacial weathering as well as glacial erosion during successive glaciations

syn and post collisional heat flow in the cenozoic eastern alps the heat flow evolution of a continental collisional zone is exemplified by the eastern alps heat flow maps for the syn collision oligocene syn extrusion early middle miocene and post extrusion late miocene recent stages are presented and are discussed in relation to the orogenic evolution continental collision during paleogene time was characterized by extremely low heat flow 150 mw m2 a few hundred kilometers south of it the former was a result of crustal thickening and of thermal blanketing due to rapid sedimentation and nappe stacking the latter was caused by slab break off and magmatic activity the early middle miocene syn extrusion stage was characterized by rapid exhumation of metamorphic core complexes tauern and rechnitz windows and by magmatic activity styrian basin both mechanisms caused extremely high heat flow 200 mw m2 in contrast the orogenetic front remained cold thereafter magmatic activity ended and uplift rates decreased thus late miocene heat flow is characterized by low to moderately high values heat flow values 75 mw m2 were restricted to the transition zone of the pannonian basin characterized by thinned crust and to the tauern window area recent temperature data indicate a subtle post miocene increase in heat flow

constraints on the active tectonics of the friuli nw slovenia area from cgps measurements and three dimensional kinematic modeling we use site velocities from continuous gps cgps observations and kinematic modeling to investigate the active tectonics of the friuli nw slovenia area data from 42 cgps stations around the adriatic indicate an oblique collision with southern friuli moving nnw toward northern friuli at the relative speed of 1 6 to 2 2 mm a we investigate the active tectonics using 3dmove a three dimensional kinematic model tool the model consists of one indenter shaped fault plane that approximates the adriatic plate boundary using the fault parallel flow deformation algorithm we move the hanging wall along the fault plane in the direction indicated by the gps velocities the resulting strain field is used for structural interpretation we identify a pattern of coincident strain maxima and high vorticity that correlates well with groups of hypocenters of major earthquakes including their aftershocks and indicates the orientation of secondary active faults the pattern reveals structures both parallel and perpendicular to the strike of the primary fault in the eastern sector which shows more complex tectonics these two sets of faults probably form an interacting strike slip system

crustal structure and active tectonics in the eastern alps 1 during the last decade a series of controlled source seismic experiments brought new insight into the crustal and lithospheric structure of the eastern alps and their adjacent tectonic provinces a fragmentation of the lithosphere into three blocks europe eu adria ad and the new pannonian fragment pa was interpreted and a triple junction was inferred the goal of this study has been to relate these deep crustal structures to active tectonics we used elastic plate modeling to reconsider the moho fragmentation we interpret subduction of eu below ad and pa from north to south and underthusting of ad mantle below pa from southwest to northeast the moho fragmentation correlates well with major upper crustal structures and is supported by gravity seismic and geodetic data an analysis of crustal thickening suggests that active convergence is associated with continued thrusting and lateral extrusion in the central eastern alps and thickening of the adriatic indenter under the southern alps according to the velocity relations at the triple junction pa moves relative to eu and ad along ene and se striking faults mainly by strike slip an eastward directed extensional component is compensated by the lateral extrusion of the central eastern alps the periadriatic insubric line east of the triple junction and the mid hungarian fault zone have relatively recently lost their role as first order active structures we favor the idea that the pannonian fragment and the tisza block merged to a soft microplate surrounded by the eastern and southern alpine carpathian and dinaric orogens