geophysical geological transect and tectonic evolution of the swiss italian alps a complete alpine cross section integrates numerous seismic reflection and refraction profiles across and along strike with published and new field data the deepest parts of the profile are constrained by geophysical data only while structural features at intermediate levels are largely depicted according to the results of three dimensional models making use of seismic and field geological data the geometry of the highest structural levels is constrained by classical along strike projections of field data parallel to the pronounced easterly axial dip of all tectonic units because the transect is placed close to the western erosional margin of the austroalpine nappes of the eastern alps it contains all the major tectonic units of the alps a model for the tectonic evolution along the transect is proposed in the form of scaled and area balanced profile sketches shortening within the austroalpine nappes is testimony of a separate cretaceous age orogenic event west directed thrusting in these units is related to westward propagation of a thrust wedge resulting from continental collision along the meliata hallstatt ocean further to the east considerable amounts of oceanic and continental crustal material were subducted during tertiary orogeny which involved some 500 km of n s convergence between europe and apulia consequently only a very small percentage of this crustal material is preserved within the nappes depicted in the transect postcollisional shortening is characterized by the simultaneous activity of gently dipping north directed detachments and steeply inclined south directed detachments both detachments nucleating at the interface between lower and upper crust large scale wedging of the adriatic or apulian lower crust into a gap opening between the subduced european lower crust and the pile of thin upper crustal flakes alpine nappes indicates a relatively strong lower crust and detachment between upper and lower crust

oxygen isotopes of phosphate and soil phosphorus cycling across a 6500 year chronosequence under lowland temperate rainforest abstract phosphorus p availability declines during ecosystem development due in part to chemical transformations of p in the soil here we report changes in soil p pools and the oxygen isotopic signature of inorganic phosphate 18op in these pools over a 6500 year soil coastal dune chronosequence in a temperate humid environment total p declined from 384 to 129 mg p kg 1 during the first few hundred years of pedogenesis due mainly to the depletion of primary mineral p in the hcl extractable pool the 18op of hcl extractable inorganic p initially reflected the signature of the parent material but shifted over time towards but not reaching isotopic equilibrium in contrast 18op signatures of inorganic p extracted in water and nahco3 approximately 9 and 39 mg p kg 1 respectively were variable but consistent with isotopic equilibrium with soil water in the naoh extractable p pool which doubled from 63 to 128 mg p kg 1 in the early stages of pedogenesis and then gradually declined the 18op of the extracted inorganic p changed from equilibrium values early in the chronosequence to more depleted signatures in older soils indicating greater rates of hydrolysis of labile organic p compounds such as dna and increase involvement in p cycling as overall p availability declines through the sequence in summary this application of 18op to a long term soil chronosequence provides novel insight into p dynamics indicating the importance of efficient recycling through tight uptake and mineralization in maintaining a stable bioavailable p pool during long term ecosystem development

changes in the 300 mb north circumpolar vortex 1963 2001 abstract the mean monthly polar stereographic map analyses of the free university of berlin terminated at the end of 2001 this paper summarizes the changes in size of the 300 mb north circumpolar vortex and quadrants for the full period of record 1963 2001 where the size has been defined by planimetering the area poleward of contours in the jet stream core a contracted vortex has tended to be a deep vortex in winter but a shallow vortex in summer during 1963 2001 there was a statistically significant decrease in vortex size of 1 5 per decade the decrease in size of western hemisphere quadrants being twice that of eastern hemisphere quadrants a significant increase in arctic oscillation ao index accompanies the significant decrease in vortex size but since the vortex contracts appreciably in all four seasons whereas the positive trend in the ao index is mainly in winter the vortex cannot serve as a proxy for the ao index the evidence for vortex contraction at the time of the 1976 77 regime

palinspastic reconstruction and topographic evolution of the eastern alps during late tertiary tectonic extrusion this paper presents a new palinspastic restoration of the eastern alps for neogene time and an attempt to reconstruct the neogene palaeogeology palaeotopography and palaeohydrography in connection with the structural evolution the eastern alps underwent radical horizontal displacement during the neogene due to large strike slip systems and formation of structural windows our palinspastic reconstruction considers a the rearrangement of tectonic units dismembered during tectonic extrusion b the tectonic denudation driven by displacement of the crystalline blocks c geochronological arguments and d the sedimentary record of the syn extrusion basins the rearrangement of tectonic blocks results in a remarkably good fit of highly dismembered zones both in crystalline and sedimentary areas and shows the pre miocene unstretched pattern of the eastern alps reduced to 65 of its present day e w elongation using this structural frame and considering the sedimentary record a set of palaeogeologic and palaeotopographic sketch maps with the palaeo river systems is presented for three time slices pre syn and post extension situation in late oligocene and early miocene times the western eastern alps were already mountainous whereas the eastern part of the orogen formed lowlands or hilly areas enhanced block movement in the course of the extrusion process around the early middle miocene boundary led to the formation of intramontane sedimentary basins and a fault induced reorientation of the drainage pattern which forms the basis of the modern river system in the area east of the tauern window this region where pre miocene land surfaces are preserved probably became a mountainous area not before late miocene time and never reached the elevations of the areas further west

the coupling of indian subduction and asian continental tectonics abstract in order to understand the potential controls on asian tectonics during the subduction of the tethys and indian lithospheres we reconstruct the coupled subduction continent deformation history using tomographic imaging kinematics constraints and numerical modeling the global p waves tomographic images of the mantle below the india asia collision zone provide constraints on the deep structure of continents and subduction history linking the slab positions in the mantle to the asian tectonics reconstructions and the indian plate kinematics we reconstruct the timing and location of successive subduction and breakoff events showing one major breakoff occurred between india and the tethys ocean 45 ma in the western syntax a vertical slab continuous to the continent is shown to override the deeper detached tethys slab in the central region similar structure is found with a detached slab yet closer to the tethys slab in the eastern syntax no slab is imaged it is inferred that after tethys slab had broke off subduction only resumed in the center of the margin while underthrusting took place at both extremities of the convergent margin during following convergence a second breakoff event detached the central indian slab from the margin 15 ma ago which renewed indian lithosphere underthrusting below asia this most probably occurred when the tibetan plateau was already uplifted implying that uplift is not a direct result of underthrusting numerical models of breakoff during subduction illustrate the controls of slab detachment on the complexities of the indian margin in these models the subduction of continental lithosphere resumes after breakoff only where this is entrained by the mantle flow associated with the long lasting oceanic slab sinking that is in the center of the margin while converging continent edges underthrusts the upper plate furthermore the breakoff during subduction has profound implications on the asian intra plate tectonics in the models the breakoff is rapidly followed by large stresses in the upper plate interiors propagating at large distance from the margin along a belt oriented at 45 from the trench the long term evolution of the asian continental tectonics shows drastic changes in the fault pattern with successive strike slip faulting across the asian continent which are in agreement with the mechanisms illustrated by the models transient large coupling at the trench caused by the breakoff events during india asia convergence offers an explanation for episodic nucleation of lithospheric faults within the asian continent and their link to deep processes

the influence of el nino southern oscillation events on the northern hemisphere 500 hpa circumpolar vortex the relationship between el nino the southern oscillation and their joint effect enso and northern hemisphere 500 hpa midlatitude circulation for the 1946 1994 observational record is determined seasonally standardized vortex positions at a spatial resolution of 5 longitude are correlated with an equatorial pacific sea surface temperature anomaly index and the southern oscillation index soi the 500 hpa circumpolar vortex is consistently expanded over the central pacific during and for the entire year following warm enso periods the vortex is contracted over north america concurrently with warm enso and to a lesser degree during the following season expansion contraction variability is also evident over east asia although the linkages to warm or cold enso are weak sea surface temperatures have a stronger association with the vortex than does the soi

tectonomagmatic characteristics of the back arc portion of the calama olacapato el toro fault zone central andes 1 post 20 ma magmatism in the central andes is either localized in the magmatic arc or distributed east of it on the altiplano puna plateau here there is a distinct concentration of magmatic centers on nw se trending lineaments such as the calama olacapato el toro cot that extends into the eastern cordillera to the east of the puna understanding the possible genetic relationship between prominent structures and magmatic centers on these lineaments is important to elucidate the tectonomagmatic evolution of the central andes we investigated the back arc area of the cot using remote sensing geological structural and petrochemical data our study demonstrates that this portion of the cot consists of nw se striking faults formed under overall left lateral transtension that decreases in activity toward the cot termini deformation on the cot occurred during and after activity of prominent n s striking transpressive fault systems and is coeval with magmatism which is focused on the central cot the most evolved magmatic rocks with an upper crustal imprint are exposed on the central cot whereas more primitive mantle derived mafic to moderately evolved magmatic rocks are found toward the cot termini this points to a genetic relationship between upper crustal deformation and magmatic activity that led to enhanced magma storage in the central cot cot magmas may result either from slab steepening or episodic delamination of the asthenospheric mantle

elliptical diagnostics of stratospheric polar vortices diagnostics based on the spatial moments of isopleths of a long lived tracer or of potential vorticity are presented that enable the structure and evolution of stratospheric polar vortices to be concisely summarized and quantified the area centre aspect ratio and orientation of the equivalent ellipse of the vortex on an isentropic surface are defined using the second and lower order spatial moments of contours within the vortex edge region by examining the variations of these elliptical diagnostics with time and altitude the temporal evolution and vertical structure of the polar vortices can be quantified the usefulness of the diagnostics is assessed by examining nitrous oxide data from the geophysical fluid dynamics laboratory skyhi general circulation model the diagnostics show and quantify several differences between the arctic and antarctic vortices in the skyhi model the arctic vortex moves further off the pole is generally more elongated and has a more complicated vertical structure than the antarctic vortex with larger variations of both the vortex centre and elongation with height the elliptical diagnostics also identify the occurrence of large scale rossby wave breaking events both at the vortex edge and in the subtropics in the model

indentation of a continent with a built in thickness change experiment and nature orogens oblique to the direction of plate convergence are currently attributed to obliquity between the margins of one or both of the sutured continents to their direction convergence we use a single analogue experiment and natural examples to illustrate a potential additional factor variations in strength of the indented continent at a high angle to the convergence direction the wavelengths of structures in laterally shortened lithosphere depend on the strength of the most competent layers lateral variations in crustal thickness must therefore lead to structures oblique to any applied lateral compression an analogue experiment was performed to explore this phenomenon a two layer indented continent was modelled by a brittle upper crust of sand above a lower crust of high viscosity polymer floating on a single layer of low viscosity syrup representing the mantle the well known strike slip structures allowing lateral escape to distant weak boundaries were hindered by lateral boundaries in front of the indenter this allowed us to focus on the effects of a thickness change built into the indented continent along a zone parallel to the direction in which a vertical rigid wall advancing at a steady rate represented the indenter vertical escape led to an orogenic belt oblique to the advancing wall this obliquity influences subsequent lateral escape model scaling and interpretations are based on extended thin sheet approximation etsa and standard theories of faulting four sectors of the alpine himalayan orogen iran tunisia the eastern alps and the himalaya are oblique to the continental convergence direction and we point to thickness changes at high angles to the suture that may account for this geometry as crustal thicknesses north of oblique sectors of the himalayas are not yet known we speculate on them we infer from the main difference between our experiment and all our examples chosen from nature that vertical orogenic escape was oblique to our model suture but can be parallel to natural sutures

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

shear wave splitting in the eastern alps observed at the transalp network data from the temporary transalp seismic network were analysed to investigate the seismic anisotropy in the upper mantle beneath the eastern alps we operated mostly short period and some broadband stations in a dense linear array which transects the eastern alps at 12 e longitude recorded sks and skks phases with different backazimuths were used simultaneously to calculate the splitting parameters of delay time and fast axis direction for each seismic station while we found variations in the delay times between 0 8 and 2 0 s the determined fast axis directions prove to be rather consistent along the profile 60 70 n they coincide well with the trend of the eastern alps thus suggesting orogen parallel flow in the upper mantle our findings support the earlier proposed idea that the adriatic indenter which was forced northwards into the european plate during the late stage of the alpine orogeny triggered an escape movement to the less constrained pannonian basin to the east

experiments on shortening of a 4 layer model of the continental lithosphere davy ph and cobbold p r 1991 experiments on shortening of a 4layer model of the continental lithosphere in p r cobbold editor experimental and numerical modelling of continental deformation tecronophysics 188 l 25 we present an experimental method for modelhng lithospheric deformation the method is based on a simplified profile of lithosphere rheology where only four layers are considered brittle crust ductile crust brittle mantle and ductile mantle the strengths of the four layers calculated from laboratory determined flow laws depend strongly on geothenns and slightly on strain rates and deformation regimes the rheological profiles of the lithosphere have been recreated in experimental models built with analog materials sand silicone putty and golden syrup which flow under their own weight during lithospheric shortening the style of deformation depends on the relative strengths of the four layers especially those in the mantle of special importance is the existence or non existence of a brittle mantle the initial stages of compression often produce flexures or buckles without local isostatic compensation buckling exerts a strong control on the localisation of thrust faults in later stages the thrusts tend to form at the inflexion points of buckles the style of crustal thickening depends on the relative thicknesses and resistances of the lithospheric layers in 2 layer lithospheric models without resistant mantle shortening was concentrated upon a small number of thrusts widely spaced in 3 layer models shortening was concentrated into a large number of reverse faults more closely spaced and more steeply dipping than before in clayer models a single thrust formed in the brittle mantle motion on this thrust dragged the crustal layers down forming an asymmetric crustal root with steep imbricate slices

classification seasonality and persistence of low frequency atmospheric circulation patterns abstract orthogonally rotated principle component analysis rpca of northern hemisphere 1 month mean 700 mb heights is used to identify and describe the seasonality and persistence of the major modes of interannual variability the analysis is detailed and comprehensive in that 1 a high resolution approximately equal area 358 point grid is used for the virtually maximum possible 35 year period of record 2 a positive bias in the nmc data base in the early 1950s in the subtropics is largely eliminated for the first time and 3 homogeneous separate analyses of each month of the year are carried out detailing the mouth to month changes in the dominant circulation patterns winter results are similar to those of other recent rpca and teleconnection studies except that some less obvious patterns are identified and further detail of the better known patterns is provided two north south dipole patterns are found over the pacific ocean west pacific oscillation and east pacific pattern and over the atla

the interplay between subduction and lateral extrusion a case study for the european eastern alps based on analogue models a series of analogue experiments simulating intra continental subduction contemporaneous with lateral extrusion of the upper plate are performed to study the interference between these two processes at crustal levels and in the lithospheric mantle the models demonstrate that intra continental subduction and coeval lateral extrusion of the upper plate are compatible processes leading to similar deformation structures within the extruding region as compared to the classical setup lithosphere scale indentation strong coupling across the subduction boundary allows for the transfer of stresses to the upper plate where strain regimes are characterized by crustal thickening near a confined margin and dominated by lateral displacement of material near a weak lateral confinement the strain regimes propagate laterally during ongoing convergence creating an area of overlap characterized by transpression when subduction is oblique to the convergence direction the upper plate is less deformed and as a consequence the amount of lateral extrusion decreases in addition strain is partitioned along the oblique plate boundary resulting in less subduction in expense of right lateral displacement close to the weak lateral confinement both oblique and orthogonal subduction models have a strong resemblance to lateral extrusion tectonics of the eastern alps europe where subduction of the adjacent adriatic plate beneath the eastern alps is debated our results imply that subduction of adria is a valid mechanisms to induce extrusion type deformation within the eastern alps lithosphere furthermore our findings suggest that the oligocene to late miocene structural evolution of the eastern alps reflects a phase of oblique subduction followed by a later stage of orthogonal subduction conform a miocene shift in the plate motion of adria oblique subduction also provides a viable mechanism to explain the rapid decrease in slab length of the adriatic plate beneath the eastern alps towards the pannonian basin

contraction of the 300 mbar north circumpolar vortex during 1963 1997 and its movement into the eastern hemisphere the size of the 300 mbar north circumpolar vortex and its partition into western and eastern hemispheres and quadrants 0 90 w 90 w 180 90 e 180 and 0 90 is estimated by planimetering the area poleward of contours in the main belt of westerlies on the polar stereographic mean monthly analyses of the institute of meteorology of the free university of berlin during 1963 1997 the trend in annual vortex size is a significant 1 4 decade vortex contraction but with the trend in the western hemisphere portion of the vortex a significant 2 1 decade compared to 0 7 decade in the eastern hemisphere portion signifying a movement of the vortex farther into the eastern hemisphere thus while on average 52 of the vortex was in the eastern hemisphere during 1963 1997 this value increased by a significant 0 4 decade during the period resulting in a substantial increase in vortex eccentricity in winter and spring the vortex has moved mainly into the asian quadrant 90 e 180 whereas in summer the vortex has become elliptical with less of a decrease in size of quadrants 90 e 180 and 0 90 w and in autumn there has been a decrease in size of quadrant 90 w 180 relative to the other quadrants the standard deviation of the annual quadrant size anomalies has decreased significantly during 1963 1997 indicating a decrease in the annual displacements of the vortex center from its mean location as the eccentricity increases and the vortex contracts on the basis of a 41 station northern hemisphere radiosonde network during 1963 1997 the annual 850 300 mbar temperature increased by a significant 0 12 c decade in the northern hemisphere as a whole and by a significant 0 17 c decade in the western half and by 0 06 c decade in the eastern half of the hemisphere the resulting association of a 1 decade decrease in 300 mbar vortex size with about an 0 1 c decade increase in 850 300 mbar temperature differs by a factor of 2 from what would be expected hydrostatically a difference that would be eliminated by an 0 4 mbar decade increase in midlatitude surface pressure during 1963 1997

relation of size and displacement of the 300 mbar north circumpolar vortex to qbo el nino and sunspot number 1963 2000 the size of the 300 mbar north circumpolar vortex and its eastern western date line and greenwich hemisphere components is estimated for the period 1963 2000 by planimetering the area poleward of 300 mbar contours in the main belt of westerlies on the mean monthly polar stereographic analyses of the institute of meteorology of the free university of berlin on the basis of the superposed epoch method there is little evidence of a relation between vortex size and phase of the qbo but significant at the 90 level or better is the tendency for the vortex to be less displaced into the eastern hemisphere in the east wind phase of the qbo for the vortex to be expanded near the time of nino 3 sea surface temperature maximum el nino but contracted 3 4 seasons after and for the vortex to be displaced farther into the date line hemisphere when there is an el nino there is also an impressive tendency for the winter vortex to be less displaced into the eastern hemisphere at the time of el nino the tendency for the vortex to be contracted near sunspot maximum and expanded near sunspot minimum is significant at only about the 80 level because of the small sample size

shape and origin of the east alpine slab constrained by the alpass teleseismic model abstract during the last two decades teleseismic studies yielded valuable information on the structure of the upper mantle below the alpine mediterranean area subducted oceanic lithosphere forms a broad anomaly resting on but not penetrating the 670 km discontinuity more shallow slabs imaged below the alpine arc are interpreted as subducted continental lower lithosphere substantial advances in our understanding of past and active tectonic processes have been achieved due to these results however important issues like the polarity of subduction under the eastern alps and the slab geometry at the transition to the pannonian realm are still under debate the alpass teleseismic experiment was designed to address these open questions teleseismic waveforms from 80 earthquakes recorded at 75 temporary and 79 permanent stations were collected during 2005 and 2006 from these data a tomographic image of the upper mantle was generated between 60 km and 500 km depth crustal corrections additional station terms and ray bending caused by the velocity perturbations were considered a steeply to vertically dipping shallow slab below the eastern alps is clearly resolved down to a depth of 250 km it is interpreted as european lower lithosphere detached from the crust and subducted during post collision convergence between adria and europe below the pannonian realm low velocities or high mantle temperatures prevail down to 300 km depth consistent with the concept of a pannonian lithospheric fragment which underwent strike slip deformation relative to the european plate and extension during the post collision phase of the alpine orogeny between 350 km and 400 km depth a deep slab extends from below the central eastern alps to under the pannonian realm it is interpreted as subducted lithosphere of the alpine tethys at greater depth there is a continuous transition to the high velocity anomaly above the 670 km discontinuity

relation between 300 mb north polar vortex and equatorial sst qbo and sunspot number and the record contraction of the vortex in 1988 89 abstract the size of the 300 mb north circumpolar vortex and quadrants has been estimated between 1963 and 1989 by planimetering the area poleward of contours in the main belt of westerlies on the 300 mb mean monthly polar stereographic maps analyzed by the meteorological institute free university of berlin the annual mean vortex was most contracted in 1989 6 4 less than average size and next most contracted in 1988 4 6 less than average size there have been three extensive vortex displacements during this period the last toward the north pacific and associated with the strong el nino of 1982 83 based on 108 seasonal deviations there has been a significant correlation of 0 39 between sea surface temperature sst in the eastern equatorial pacific and vortex size three seasons later that is the vortex has tended to be contracted following el nino there has been a highly significant correlation of 0 45 between this sst and the size of quadrant 90 w 180 in the same season that is this el n

coeval high pressure metamorphism thrusting strike slip and extensional shearing in the tauern window eastern alps 1 recent findings for a young 31 5 0 7 ma age of high pressure metamorphism at 90 km depths in the eclogite zone of the tauern window eastern alps prompt the question about the timing of the structural development of the tauern window and its relation to high pressure metamorphism we show that all major structures in the tauern window resulting from strong n s lithospheric shortening and simultaneous minor e w extension began developing coevally with high pressure metamorphism in the eclogite zone large scale strike slip shear zones started to form at 32 30 ma and facilitated the spatial accommodation of simultaneous shortening and extension at least some of the strike slip and extensional shear zones operated into the middle miocene either continuously or intermittently with pronounced activity at 21 15 ma the considerable exhumation of the eclogite zone from 90 km depths into the middle crust and the tectonic development of its framework occurred within only 1 2 ma after eclogitization this is evidenced by almost identical ages for eclogite facies metamorphism and for the development of the major structures that bound the eclogite zone under blueschist and greenschist facies metamorphic conditions we discuss a tectonic model in which considerable transpressional shortening and thickening took place in the present central southern part of the tauern window we propose that the tauern window nucleated here and that most of the regional deformation at 32 30 ma is today found at the periphery of the window and in the adjacent austroalpine units afterward transpression continued the window grew to the e w and n and deformation progressed to those parts of the window ductile deformation in the present day surface level ceased at 15 ma

influence of the arctic circumpolar vortex on the mass balance of canadian high arctic glaciers abstract variability in july mean surface air temperatures from 1963 to 2003 accounted for 62 of the variance in the regional annual glacier mass balance signal for the canadian high arctic a regime shift to more negative regional glacier mass balance occurred between 1986 and 1987 and is linked to a coincident shift from lower to higher mean july air temperatures both the interannual changes and the regime shifts in regional glacier mass balance and july air temperatures are related to variations in the position and strength of the july circumpolar vortex in years when the july vortex is strong and its center is located in the western hemisphere positive mass balance anomalies prevail in contrast highly negative mass balance anomalies occur when the july circumpolar vortex is either weak or strong without elongation over the canadian high arctic and its center is located in the eastern hemisphere the occurrence of westerly positioned july vortices has decreased by 40 since 1987 the associat

lithospheric scale analogue modelling of collision zones with a pre existing weak zone lithospheric scale analogue experiments have been conducted to investigate the influence of strength heterogeneities on the distribution and mode of crustal scale deformation on the resulting geometry of the deformed area and on its topographic expression strength heterogeneities were incorporated by varying the strength of the crust and upper mantle analogue layers and by implementing a weak plate or part of a plate between two stronger ones three brittle crust viscous crust strong viscous upper mantle and four brittle crust viscous crust brittle upper mantle strong viscous upper mantle layer models were confined by a weak silicone layer on one side in order to contain but not oppose lateral extrusion experimental results show that relative strength contrasts between converging plates and intervening weak plates control the location and the shape of deformation sites taken as collision orogens if the contrast is small internal deformation of the strong plates through fore and backthrusting occurs early in the deformation history however the bulk system is dominated by buckling that nucleates on the weak plate whose antiformal topography is highest model moho of the bordering stronger plates is deepest under these conditions if the contrast is large deformation remains localized within the weak plate for a larger amount of shortening and develops a root zone below a narrow deformation belt which coincides with the locus of maximum topography implementing a buoyant low viscosity layer above the model moho of the weak plate favours the development of asymmetric model orogens notwithstanding the initial symmetric setup once the asymmetry is established strain remains localized in thrust faults and ductile shear zones documenting foreland directed displacement of the model orogen such laterally and vertically irregular configurations have applications in continent continent collision settings such as the eastern alps first order mechanical boundary conditions recognized from modelling to be favourable to the post early oligocene tectonics of the eastern alps include 1 subtle rather than high strength contrasts between the adriatic indentor and the strongly deformed region comprising penninic and austroalpine units to the north of it 2 decoupling of penninic continental upper crust from its substratum to allow for crustal scale buckling of the tauern window 3 weak mechanical behaviour of the european lower crust during collision to account for its constant thickness along the transalp deep seismic transect and 4 the direct continuation of the basal detachment underlying the fold and thrust belt in the hangingwall of the european plate with a wide ductile shear zone in the core of the orogen which separates the european from the adriatic plate the geological society of london 2005

recent widening of the tropical belt evidence from tropopause observations 1 radiosonde measurements and reanalysis data are used to examine long term changes in tropopause behavior in the subtropics tropopause heights in the subtropics exhibit a bimodal distribution with maxima in occurrence frequency above 15 km characteristic of the tropical tropopause and below 13 km typical of the extratropical tropopause both the radiosonde and reanalysis data show that the frequency of occurrence of high tropopause days in the subtropics of both hemispheres has systematically increased during the past few decades so that tropical characteristics occur more frequently in recent years this behavior is consistent with a widening of the tropical belt and the data indicate an expansion of about 5 8 latitude during 1979 2005

wavelet analysis of polar vortex variability over the twentieth century recent increases in extreme weather events in the northern hemisphere have been linked to amplified planetary waves changes in planetary wave properties are linked to changes in climate hence finding a mechanism that links the planetary wave variability under climatic forcing and midlatitude blocking events has engendered a great deal of interest in this study wavelet analysis is applied to time series of planetary wave phase speeds at high latitudes as a first step to assessing the potential for identifying these mechanisms in the observational record a circumpolar multiannual cycle increase is found but signals also demonstrate a complex westward propagation pattern with periods of intense wave variability significant correlations between wavelet power at all time scales and albedo snow cover atmospheric ozone levels and surface air temperature are demonstrated

the effect of convergence angle on the kinematic evolution of strain partitioning in transpressional brittle wedges insight from analog modeling and high resoluiton digital image analysis 1 using analog modeling aided by digital image analysis dpiv we constrained the long term kinematic evolution of strain partitioning in transpressional brittle wedges as a function of convergence angle we ran a series of dry quartz sand experiments representing highly oblique continent continent collision convergence angles of 4 to 30 the digital image analysis provided high resolution constraints on the long term kinematic evolution of these wedges which could be subdivided in distinct kinematic stages comprising 1 an initial distributed strain stage and 2 an oblique wedge stage before 3 the stage of strain partitioning is reached thus we document the evolution of different deformation stages from a single plate tectonic boundary condition in addition the relationship between convergence angle kinematic stages and wedge geometry including fault dips and fault hierarchy was established the modeling results show that smaller convergence angles lead to steeper faults besides for a constant convergence angle the proshears that evolved during the strain partitioning stage were less steep than those formed during the oblique wedge stage the fault slip vector on individual fault segments was derived from the dpiv data set for each time increment quantifying the magnitude and orientation of slip on fault segments during the different kinematic stages in addition in the 7 5 and 15 models rotation of the slip vector by up to 40 was observed on a single proshear during the strain partitioning stage these observations allow to some degree a validation of existing analytical models of strain partitioning in particular the assumption of steady state

impact of coral spawning on the biogeochemistry of a hawaiian reef abstract we examined the impact of montipora capitata coral spawning on local biogeochemistry in kane ohe bay hawai i this event supplied labile spawn derived organic matter sdom to the water column triggering a cascading series of related effects on the biogeochemistry of the reef specifically we measured the isotopic composition and nutrient ratios of spawning material and coral tissues and utilized these signatures to track pathways of sdom incorporation into this coral dominated ecosystem we observed 1 shifts in the isotopic signatures of coral tissues after the spawning event 2 rapid turnover of sdom within the water column and enhanced deposition of pom to the sediment surface 3 enhanced sediment efflux of nh 4 after the spawning event that triggered a phytoplankton bloom in the overlying water and 4 drawdown of dissolved nutrients in the water column after spawning that coincided with the occurrence of a water column phytoplankton bloom our results show that single species spawning events can serve as a source of substantial nutrient input to the water column contributing in similar ways to storm driven river nutrient input and with measurable impact on the biogeochemistry of the reef

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

late stage differential exhumation of crustal blocks in the central eastern alps evidence from fission track and u th he thermochronology thermal history modelling based on zircon and apatite fission track and apatite u th he data constrain and refine the near surface exhumation of the south eastern tauern window penninic units and neighbouring austroalpine basement units in the eastern alps fast exhumation on both sides of the penninic austroalpine boundary coincides with a period of lateral extrusion and tectonic denudation of the penninic units in miocene time 22 12 ma the jump to older ages occurs within the austroalpine unit along the polinik fault which therefore defines the boundary between the tectonically denuded units and the hangingwall at that time according to the different u th he ages between the penninic hochalm and sonnblick domes we demonstrate a differential cooling history of these two domes in the latest miocene and early pliocene

lithospheric scale structures from the perspective of analogue continental collision abstract analogue models were employed to investigate continental collision addressing the roles of 1 a suture zone separating different crustal blocks 2 mid crustal weak layers and 3 mantle strengths these models confirmed that low amplitude lithospheric and crustal buckling is the primary response to shortening with a wavelength mainly controlled by the strong upper crust and or lithospheric mantle with increasing shortening bivergent thrusts formed across the brittle layers equivalent to upper crust at inflection points of the buckles while ductile layers lower crust and mantle continued being folded the resulting geometries displayed pop ups and pop downs above the boundaries sutures between blocks further shortening led to wider thrust bounded deformation zones belts in front of the stronger blocks identified as effective indenters during shortening upward extrusion into belts allowed exhumation of deep material weak layers enhanced strain localisation these modelling results have similarity in large scale structures of modern orogens and are relevant to the understanding of natural collisional processes

palaeomagnetic evidence for tertiary counterclockwise rotation of adria abstract with the aim of obtaining tertiary palaeomagnetic directions for the adriatic foreland of the dinaric nappe system we carried out a palaeomagnetic study on platform carbonates from stable istria from the northwestern and the central dalmatia segment of imbricated adria despite the weak to very weak natural remanences of these rocks we obtained tectonically useful palaeomagnetic directions for 25 sites from 20 localities all exhibit westerly declinations both before and after tilt correction concerning the age of the magnetizations we conclude that five subhorizontal and magnetite bearing eocene localities from stable istria are likely to carry primary remanence whereas three tilted and hematite bearing ones were remagnetized in the northwestern segment of imbricated adria the cluster of the mean directions improved after tectonic correction indicating pre tilting magnetization in contrast maastrichtian eocene platform carbonates from central dalmatian were remagnetized in connection with the late eocene oligocene deformation or miocene hydrocarbon migration based on the appropriate site locality means we calculate mean palaeomagnetic directions for the above three areas and suggest an alternative interpretation of the data of kissel et al j geophys res 100 1995 14999 for the flysch of central dalmatia the four area mean direction define a regional palaeomagnetic direction of dec 336 inc 52 k 107 95 9 from these data we conclude that stable istria in close coordination with imbricated adria must have rotated by 30 counterclockwise in the tertiary relative to africa and stable europe we suggest that the latest miocene early pliocene counterclockwise rotations observed in northwestern croatia and northeastern slovenia were driven by that of the adriatic foreland i e the rotation of the latter took place between 6 and 4 ma

decoupling during continental collision and intra plate deformation abstract fundamental aspects of mountain building such as the dominant deformation mechanism strain localisation and topography development in response to the presence of decoupling zones either along boundaries of weak and strong lithospheres or within weak domains of continental lithosphere are studied by analogue lithospheric models scenarios are investigated where a weak part of the lithosphere is bordered on either side by stronger lithospheres geometries of the weak zone vary from box to wedge to graben shaped representing lateral strength variations as a consequence of earlier deformation phases the rheologic and geometric configuration at the onset of shortening is therefore considered as representative for continental collision and intra plate settings the modelling results show that the geometric and topographic evolution of mountain belts through time is sensitive to the presence of decoupling horizons along plate or tectonic boundaries this is because the decoupled boundaries localise strain control the dominant deformation mechanism and hence the locus of uplift and subsidence accordingly decoupled boundaries favour deformation by thrusting and particularly in the case of an initially wedge shaped weak zone the development of mountain belts with overall triangular shape in contrast lithospheres with coupled boundaries dominantly deform by buckling irrespective of the initial geometry of the weak zone as this deformation mechanism affects all model domains it produces a distinguishable pattern of uplift and subsidence controlled by buckling strong decoupling at mid crustal levels within the weak zone favours vertical strain partitioning and the formation of plateau shaped mountains the modelling results suggest that natural collisional systems should respond to an increase in plate coupling through time by widespread uplift of the mountain belt including its foreland basins which were formerly created under decoupled conditions due to the absence of decoupling zones like plate contacts weak domains in intra plate settings are predicted to deform dominantly by buckling

basin formation during the post collisional evolution of the eastern alps the example of the lavanttal basin the miocene lavanttal basin formed in the eastern alps during extrusion of crustal blocks towards the east in contrast to basins which formed contemporaneously along the strike slip faults of the noric depression and on top of the moving blocks styrian basin little is known about the lavanttal basin in this paper geophysical sedimentological and structural data are used to study structure and evolution of the lavanttal basin the eastern margin of the 2 km deep basin is formed by the wnw trending koralm fault the geometry of the gently dipping western basin flank shows that the present day basin is only a remnant of a former significantly larger basin late early karpatian and early middle miocene badenian pull apart phases initiated basin formation and deposition of thick fluvial granitztal beds lacustrine and marine muhldorf fm sediments the muhldorf fm represents the lower badenian cycle tb2 4 another flooding event caused brackish environments in late middle miocene early sarmatian time whereas freshwater environments existed in late sarmatian time the coal bearing sarmatian succession is subdivided into four fourth order sequences the number of sequences suggests that the effect of tectonic subsidence was overruled by sea level fluctuations during sarmatian time increased relief energy caused by early pannonian pull apart activity initiated deposition of thick fluvial sediments the present day shape of the basin is a result of young plio pleistocene basin inversion in contrast to the multi stage lavanttal basin basins along the noric depression show a single stage history similarities between the lavanttal and styrian basins exist in early badenian and early sarmatian times

upper mantle structure beneath the alpine orogen from high resolution teleseismic tomography 1 to understand the evolution of the alpine orogen knowledge of the actual structure of the lithosphere asthenosphere system is important we perform high resolution teleseismic tomography with manually picked p wave arrival times from seismograms recorded in the greater alpine region the resulting data set consists of 4199 relative p wave arrivals and 499 absolute p wave arrivals from 76 teleseismic events corrected for the contribution of the alpine crust to the travel times the three dimensional 3 d crustal model established from controlled source seismology data for that purpose represents the large scale alpine crustal structure absolute p wave arrival times are used to compute an initial reference model for the inversion tests with synthetic data document that the combination of nonlinear inversion high quality teleseismic data and usage of an a priori 3 d crustal model allows a reliable resolution of cells at 50 km 50 km 30 km hence structures as small as two cells can be resolved in the upper mantle our tomographic images illuminate the structure of the uppermost mantle to depth of 400 km along strike of the alps the inversion reveals a high velocity structure that dips toward the se beneath the adriatic microplate in the western and central alps in the eastern alps we observe a northeastward dipping feature subducting beneath the european plate we interpret this feature in the western and central alps as subducted mainly continental european lower lithosphere for the east we propose that parts of the vardar oceanic basin were subducted toward the ne forcing continental adriatic lower lithosphere to subduct northeastward beneath the european plate

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

height of faceted spurs a proxy for determining long term throw rates on normal faults evidence from the north baikal rift system siberia 1 we present new results on the long term throw rates of active normal faults in the north baikal rift nbr eastern siberia based on a statistical analysis of triangular faceted scarps fault bounded ridges in the nbr display typical morphologies with several contiguous facets separated by fault perpendicular catchments over a range of 20 fault segments analyzed triangular facet heights vary from 200 to 900 m as fault scarps have been developing under similar long term climatic conditions we infer that the scatter in mean facet height arises from long term differences in fault throw rate we compare the morphology of nbr facets with results obtained in a previously published numerical model of facet growth using facet height as an input model results provide estimates of the long term fault throw rate nbr throw rates vary between 0 2 and 1 2 mm yr 1 the throw rates are then compared with the cumulated throw which has been constrained by geophysical and stratigraphic data in the basins this provides an estimate of the age of fault and basin initiation we show that the modern stage of basin development started circa 3 myr ago except for the north baikal basin 8 ma our results also suggest that a proportion of the observed throw is inherited from an earlier tectonic stage

the arctic oscillation signature in the wintertime geopotential height and temperature fields the leading empirical orthogonal function of the wintertime sea level pressure field is more strongly coupled to surface air temperature fluctuations over the eurasian continent than the north atlantic oscillation nao it resembles the nao in many respects but its primary center of action covers more of the arctic giving it a more zonally symmetric appearance coupled to strong fluctuations at the 50 hpa level on the intraseasonal interannual and interdecadal time scales this arctic oscillation ao can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft it is proposed that the zonally asymmetric surface air temperature and mid tropospheric circulation anomalies observed in association with the ao may be secondary baroclinic features induced by the land sea contrasts the same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature sea level pressure and 50 hpa height over the past 30 years parts of eurasia have warmed by as much as several k sea level pressure over parts of the arctic has fallen by 4 hpa and the core of the lower stratospheric polar vortex has cooled by several k these trends can be interpreted as the development of a systematic bias in one of the atmosphere s dominant naturally occurring modes of variability

pyrite oxidation during sample storage determines phosphorus fractionation in carbonate poor anoxic sediments abstract we investigated the phosphorus p and iron fe fractionation in four cores with anoxic sediments deposited during the mid cretaceous oceanic anoxic event 2 94 ma and the paleocene eocene thermal maximum 55 ma that were exposed to oxygen after core recovery surprisingly p associated with iron oxyhydroxides fe bound p was a major p phase in these laminated sediments deposited under euxinic conditions a significant fraction of total fe was present as poorly crystalline ferric fe this fraction increased with increasing storage time of the investigated cores in carbonate poor samples fe bound p accounted for up to 99 of total p and its abundance correlated with pyrite contents in samples with higher caco3 contents 5 wt in the investigated samples p was mostly present in authigenic ca p minerals irrespective of pyrite contents we conclude that the p fractionation in anoxic carbonate poor sediments is strongly affected by pyrite oxidation that occurs when these sediments are exposed to oxygen pyrite oxidation produces sulfuric acid and iron oxyhydroxides the abundance of poorly crystalline fe oxyhydroxides provides further evidence that these were indeed formed through recent post recovery oxidation rather than in situ tens of millions of years ago the acid dissolves apatite and the released phosphate is subsequently bound in the freshly formed iron oxyhydroxides pyrite oxidation thus leads to a conversion of authigenic ca p to fe bound p in more calcareous samples caco3 can act as an effective buffer against acidic dissolution of ca p minerals the results indicate that shielding of sediments from atmospheric oxygen is vital to preserve the in situ p fractionation and to enable a valid reconstruction of marine phosphorus cycling based on sediment records

northern hemisphere circumpolar vortex trends and climate change implications 1 trends in the northern hemisphere circumpolar vortex at 700 500 and 300 hpa are examined to assess the relationship between circulation variability and air temperature a vortex climatology is developed for the period 1949 2000 at each pressure level three geopotential height contours are used to quantify the size and position of the vortex at 5 longitude resolution within and both north and south of the primary hemispheric baroclinic zone this combination of spatial specificity and the long temporal record makes this the most comprehensive vortex climatology to date the overall and seasonal vortex time series for the northern hemisphere are created for northern middle and southern contours at each of the three levels in the atmosphere from the beginning of the record until 1970 the vortex exhibits a statistically significant expansion but the vortex has been contracting significantly since then at all levels the pre 1970 expansion and subsequent contraction is strongest in the lower latitudes and weakest in the higher latitudes the trends are also stronger in the upper troposphere than in the lower troposphere spatial examination of the vortex indicates that the pre 1970 expansion and post 1970 contraction were driven primarily by expansion contraction over asia europe and north america with little change over the northern hemisphere oceans although significant climate change debate focuses on the discrepancy between positive trends in surface air temperature and little or no trends in microwave sounding unit msu satellite temperatures contraction of the circumpolar vortex at every level of the atmosphere implies that the atmosphere is warming at depth since 1970 comparisons with the msu temperature history indicate that the northern hemisphere circulation as a whole as represented by the circumpolar vortex accounts for almost two thirds of the interannual variability in midlatitude msu temperature indicating that vortex size and position are coupled strongly to atmospheric temperature and could be a good indicator of climate change on a latitude by latitude and level by level basis the lower latitudes are associated most strongly with msu temperature in the midtroposphere while the middle and higher latitudes are more closely associated with msu temperature in the upper troposphere the vortex trends are also similar to observed surface warming trends

transition from orogen perpendicular to orogen parallel exhumation and cooling during crustal indentation key constraints from 147sm 144nd and 87rb 87sr geochronology tauern window alps abstract the core of the alpine orogen in the eastern alps tauern window experienced a change from orogen normal shortening and post nappe doming to predominantly orogen parallel extension and tectonic unroofing during late oligocene to miocene northward indentation of the adriatic microplate a new 147 sm 144 nd isochron age of 25 7 0 9 ma on a garnet bearing assemblage from the lowest nappe complex forming a dome in the eastern part of the tauern window indicates that high temperatures related to post nappe barrovian type metamorphism overlapped in time with the onset of doming new 87 rb 87 sr biotite ages from this same complex combined with previously published 87 rb 87 sr white mica ages suggest that doming and exhumation began no later than 28 ma immediately in front of indenting austroalpine crustal blocks then migrated laterally to the ese during rapid exhumation and orogen parallel stretching beginning at about 23 ma rapid cooling ended at approximately 17 ma in the footwall of the katschberg normal fault which delimits the eastern margin of the tauern window a similar pattern of migrating doming orogen parallel extension and cooling is recognized in the western part of the tauern window where rapid exhumation began at about 20 ma some 2 3 ma later than in the eastern part this difference in the onset of rapid exhumation as well as the overall migration of doming from the center to the ends of the tauern window are attributed to fragmentation of the aforementioned austroalpine blocks along the leading edge of the main adriatic indenter southern alps as this indenter advanced to the north

displacements of the north circumpolar vortex during el nino 1963 83 abstract during the pronounced 1982 83 el nino the 300 mb north circumpolar vortex was displaced further toward japan from its mean seasonal locations than observed since the beginning of the vortex record in 1963 however during the strong 1972 73 el nino the vortex was displaced toward the 180th meridian and during the weaker 1965 66 el nino toward the eastern pacific so that vortex displacements are not indicated to have been the same for different el nino episodes based on the full 21 year record the vortex has tended to be displaced toward 90 w when sea surface temperature sst in the region 0 10 s 180 80 w was above average but toward the 180th meridian when the magnitude of sst deviation from average is considered

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

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