aftsolve a program for multi kinetic modeling of apatite fission track data aftsolve is a computer program for deriving thermal history information from apatite fission track data it implements a new fission track annealing model that takes into account the known kinetic variability among different apatite species to fully utilize this model a fission track worker must obtain data that can be used to infer the kinetic characteristics of each apatite grain from which a measurement was taken such data can consist of etch figure lengths or chemical composition the benefit of this overall approach is that it allows useful information to be derived from previously unusable analyses extends the practical range of geological temperatures constrained by fission track analyses and increases overall confidence in model predictions aftsolve also incorporates the effects of fission track orientation relative to the apatite crystallographic c axis variation in initial track length and the biasing effect of 2 5 2 cf irradiation for enhancing confined horizontal track length detection aftsolve is written for windows operating systems and has a graphical interface that allows interactive input of thermal histories and real time generation of estimates for fission track length distributions and ages for up to six simultaneously modeled kinetic populations it also includes procedures for estimating the range of time temperature histories that are statistically consistent with a data set and constraints entered by the user

evolution of large normal faults evidence from seismic reflection data recent advances have been made in understanding how extensional faults and basins develop as faults propagate and link evidence for these linkage patterns in seismic reflection data can be seen in data from east africa early fault linkage patterns for boundary faults can follow three possible paths fault linkage and propagation occur either 1 prior to significant basin formation 2 after minor faulting has created an extensive area of subsidence or 3 during basin development the data from east africa show examples mainly of paths 1 and 2 transverse anticlines anticlines developed parallel to and in the hanging wall of the strike of faults associated with boundary faults are common features they represent either the sites of old synthetic transfer zones or a region of low fault displacement along the strike of a fault where two or more depocenters of different ages overlap as fault activity decreases over time displacement tends to be concentrated on progressively narrower parts of the fault this pattern is developed particularly well in continental rifts and may help discriminate late synrift sedimentation from postrift sedimentation where strike lines across the hanging wall of the fault are observable

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

subsurface fault geometries and crustal extension in the eastern basin and range province western u s abstract we provide the first synthesis of seismic reflection data and active present day crustal deformation for the greater wasatch fault zone we analyzed a number of previously unpublished seismic reflection lines horizontal and vertical crustal velocities from continuous gps and surface geology to investigate the relationships between interseismic strain accumulation subsurface fault geometry and geologic slip rates on seismogenic faults across the eastern third of the northern basin and range province the seismic reflection data show recent activity along high angle normal faults that become listric with depth and appear to sole into preexisting decollements possibly reactivating them we interpret these listric normal faults as reactivated sevier age structures that are connected at depth with a regionally extensive detachment horizon these observations of subsurface structure are consistent with the mapped geology in areas that have experienced significant extension we modeled the crustal deformation data using a buried dislocation source in a homogeneous elastic half space the estimated model results include a low angle dislocation 8 20 at a locking depth of 7 10 km and slipping at 3 2 0 2 mm yr despite the model s relative simplicity we find that the predicted location of the dislocation is consistent with the interpreted seismic reflection data and suggests an active regionally extensive sub horizontal surface in the eastern basin and range this result may imply that this surface represents aseismic creep across a reactivated low angle fault plane or the onset of ductile flow in the lower crust at or beneath the brittle ductile transition zone under the present day basin and range extensional regime this result may also have implications for crustal rheology and suggests that geodesy might under some circumstances serve as an appropriate tool for inferring deeper crustal structure

metallogenic evolution of convergent margins selected ore deposit models abstract metallogenic patterns in convergent margin arcs are related to thickness of the arc crust and its petrologic evolution which are themselves linked by a positive correlation between average silica content of arc rocks and average thickness of arc crust in general tin mercury antimony and fluorine are most abundant in areas of thickest crust although the composition of ore deposits is strongly controlled by deep crustal and mantle features the actual form and type of many ore deposits is controlled by upper crustal features particularly the relative abundance of carbonate and silicate country rock for instance epithermal precious metal deposits are commonly associated with subaerial silicic volcanism which generally forms in the later stages of arc evolution deposits of this type will be absent if arc volcanism is terminated prematurely or removed if subduction of thickened or hot oceanic crust causes extreme uplift and consequent erosion of the upper parts of the arc similarly chimney manto limestone replacement lead zinc silver deposits are common only in terranes with extensive thick limestone units which are commonly formed in shallow shelf environments several important types of convergent margin deposits remain poorly understood acid sulfate deposits in primitive oceanic volcanic arcs are associated with bimodal volcanic suites that appear to have formed at an early stage in the evolution of the arc alkaline porphyry copper deposits are closely associated with calc alkaline porphyry copper deposits commonly in the same volcanic arc although they appear to have formed farther back from the trench or during periods of oblique subduction or arc reversal massive iron oxide deposits and related base and precious metal mineralization are closely associated with silicic magmas that form during later stages of arc evolution in addition to tectonic and petrologic factors metallogenic patterns probably reflect global forcing mechanisms the most important of which are global seawater anoxia and plate reorganizations global anoxia produces deep water environments that favor sedex mineralization and can promote subsurface ore deposition where anoxic bottom waters recharge underlying aquifers plate reorganizations can lead to ore deposition by providing extensional environments in the upper crust and possibly by facilitating partial melting of oceanic crust that has been modified by earlier subducting slabs

contemporary tectonics of the wasatch front region utah from earthquake focal mechanisms we have completed a comprehensive study of focal mechanisms of digitally recorded earthquakes ml 4 4 that occurred in the wasatch front region in utah during 1980 to 1986 single event solutions for 24 events were determined using recently revised crustal models and a computerized grid search technique overall the mechanisms show predominantly normal faulting on n s striking nodal planes of moderate to steep dip 30 tension axis azimuths average 96 12 thus in general the mechanisms indicate e w to ese wnw crustal extension and vertical crustal shortening oblique slip when observed is characterized by left lateral motion on planes striking n to ne or right lateral motion on planes striking n to nw most of the mechanisms with significant amounts of oblique slip motion occur in the southern part of the study area where compression axis orientations range from near vertical to near horizontal thus the mechanisms suggest a possible change in stress regime from north to south along the wasatch front despite geologic evidence for low angle faults in the study area shallowly dipping nodal planes are relatively uncommon

holocene vertical displacement on the central segments of the wasatch fault zone utah compiled per event vertical displacement observations from 17 paleoseismic sites along the six central segments of the wasatch fault zone wfz highlight possible biases and trends in displacement along the fault the displacement data are consistent with a model of characteristic type slip but anomalous and variable displacements indicate that significant natural variability in displacement occurs when combined into a composite distribution of displacement 79 of the data fit within a displacement envelope that shows displacement decreasing in a half ellipse shape from 1 4 3 5 m near the segment centers to 0 6 2 5 m near the ends additionally displacements normalized by the distance from the segment centers to ends decrease from means of 2 0 3 0 m near the segment centers to 1 3 1 9 m near the ends consistent with characteristic type slip termination although several paleoseismic sites exhibit repeated similar displacements the data are sparse and both low valued 0 5 0 8 m and high valued 4 2 4 7 m outliers suggest complex strain release possibly resulting from segment interaction and or noncharacteristic events although a global normal fault type surface rupture length srl average displacement regression underpredicts observed wfz displacements the largest displacements per segment correspond well with a srl maximum displacement regression this correlation as well as moderate variability in srl and displacement based moment magnitude suggests that the anomalous displacements represent the intrinsic variability in characteristic displacement per segment thus minor variations to the characteristic slip model to account for exceptional upper and lower bound displacements e g a hybrid characteristic variable slip model may be appropriate for the wfz additional paleoseismic data are necessary to address data gaps and biases to facilitate more robust tests of earthquake slip models and to reduce uncertainty in srl displacement and magnitude

intraplate extensional tectonics of the eastern basin range inferences on structural style from seismic reflection data regional tectonics and thermal mechanical models of brittle ductile deformation the general lack of a correlation between earthquakes and surface faulting in the interior of the western u s cordillera has motivated our efforts to evaluate the geometry structural style and mechanism of normal faulting characteristic of this region of intraplate extension to address the problem we have interpreted over 1500 km of seismic reflection data and constructed detailed cross sections of the upper crust rheological models of the continental crust were calculated to examine the possibility of shallow quasi plastic flow and its influence on faulting in the eastern basin range the western colorado plateau and the middle rocky mountains our data and interpretations have revealed the following styles of cenozoic deformation 1 steep to low angle dip normal faulting along the wasatch fault 2 low angle dip and listric normal faulting possibly associated with movement on preexisting thrusts 3 the occurrence of asymmetric mostly eastward tilted tertiary basins that are bounded by low to moderate dipping planar and listric faults and 4 at least three vertically stacked en echelon low angle reflections in the mid to upper crust that dip gently westward from 3 km beneath the wasatch plateau to over 15 km at the utah nevada border these reflections are interpreted as normal detachment faults the structural style of the pervasive low to moderate angle dipping faults cannot be easily reconciled with classic brittle failure theory but the interpreted termination of normal faults at or above the deeper low angle reflections suggests the presence of shallow zones of ductile deformation that may have accommodated slip an important observation based on interpretations of seismic reflection profiles is that normal fault zones dip more gently in the subsurface than their associated scarps in unconsolidated surficial deposits segment boundaries of the wasatch fault zone apparently coincide with the positions of east trending displacement transfer structures in thrust sheets and the position of the precambrian uinta aulacogen suggesting that preexisting crustal structure partly controls the geometry of extension to examine the influence of ductile deformation quasi plastic flow was modeled for appropriate geotherms of the basin range and colorado plateau crusts these models provide constraints on the depth to the frictional quasi plastic transition that occurs as shallow as 8 km in the eastern basin range this depth also corresponds to the approximate depth above which most accurately determined earthquake foci for small earthquakes m 5 5 appear to nucleate at 10 15 km in or near the brittle ductile transition the rheological modeling suggests that a thermally deforming continental lithosphere plays an important role in the evolution of this extending intraplate region large scale low angle reflections may represent decollements and normal faults at the top of upper crustal zones of reduced shearing strength and higher ductility

holocene paleoseismicity temporal clustering and probabilities of future large m 7 earthquakes on the wasatch fault zone utah the chronology of m 7 paleoearthquakes on the central five segments of the wasatch fault zone wfz is one of the best dated in the world and contains 16 earthquakes in the past 5600 years with an average repeat time of 350 years repeat times for individual segments vary by a factor of 2 and range from about 1200 to 2600 years four of the central five segments ruptured between 620 30 and 1230 60 calendar years b p the remaining segment brigham city segment has not ruptured in the past 2120 100 years comparison of the wfz space time diagram of paleoearthquakes with synthetic paleoseismic histories indicates that the observed temporal clusters and gaps have about an equal probability depending on model assumptions of reflecting random coincidence as opposed to intersegment contagion regional seismicity suggests that for exposure times of 50 and 100 years the probability for an earthquake of m 7 anywhere within the wasatch front region based on a poisson model is 0 16 and 0 30 respectively a fault specific wfz model predicts 50 and 100 year probabilities for an m 7 earthquake on the wfz itself based on a poisson model as 0 13 and 0 25 respectively in contrast segment specific earthquake probabilities that assume quasi periodic recurrence behavior on the weber provo and nephi segments are less 0 01 0 07 in 100 years than the regional or fault specific estimates 0 25 0 30 in 100 years due to the short elapsed times compared to average recurrence intervals on those segments the brigham city and salt lake city segments however have time dependent probabilities that approach or exceed the regional and fault specific probabilities for the salt lake city segment these elevated probabilities are due to the elapsed time being approximately equal to the average late holocene recurrence time for the brigham city segment the elapsed time is significantly longer than the segment specific late holocene recurrence time

propagation and resonance of sh waves in the salt lake valley utah abstract the salt lake valley is an alluvium valley where seismic amplification measured at some sites can exceed a factor of 10 relative to hard rock sites adjacent to the basin it is important to understand the causes for these amplifications in order to predict which sites in the salt lake valley are most prone to strong ground shaking towards this end finite difference synthetic seismograms were used to successfully characterize key parameters controlling low frequency sh wave amplification in the salt lake valley plane wave source synthetic seismograms reveal that sh wave amplification in the frequency band 0 2 to 2 0 hz is primarily controlled by the two shallowest lithologic units the 0 25 to 1 0 km thick unconsolidated alluvial quaternary sediments v s 0 98 km sec and the underlying 0 5 to 1 0 km thick semi consolidated tertiary sediments v s 1 42 km sec the quaternary sediments tend to increase the coda duration while the semi consolidated tertiary sediments act as a wave guide to trap the low frequency seismic energy it is also found that the basin can cast a seismic shadow over adjacent bedrock sites inhibiting seismic wave propagation to sites adjacent to the basin calibration of valley site amplification to these bedrock sites may result in overestimation of basin site amplification finite difference synthetic seismogram modeling can clearly demonstrate the significant effects of deep basin lithology and geometry on low frequency site amplification observed across the salt lake valley

fission track lengths in the apatite annealing zone and the interpretation of mixed ages abstract measurements of confined fission tracks in apatites from deep boreholes show that their mean length is reduced and the length distribution becomes progressively broader through the fission track annealing zone at subsurface temperatures of around 100 c and above the length distribution characteristically becomes very broad without a pronounced peak the lengths of the longest tracks remain essentially constant at all stages of natural annealing observed in the boreholes this pattern is similar to that found in laboratory annealing of spontaneous fission tracks in apatite from an outcrop sample of the same formation these observations show that confined track lengths can be used as important indicators of the type of thermal history that a sample has experienced in the temperature zone of increasing track stability the length distributions reported here provide a basis for interpretation of fission track ages that might otherwise be ambiguous an apatite age which results from a uniform slow cooling history will have a broad negatively skewed length distribution while a bimodal distribution provides clear evidence of a two stage history involving partial annealing by a discrete thermal event the apparent fission track age associated with a bimodal length distribution will be a mixed age intermediate between the original age and that of the later event

tectonic evolution of the cenozoic olympic subduction complex washington state as deduced from fission track ages for detrital zircons

constraining depth to basement for mineral exploration using microtremor a demonstration study from remote inland australia abstractwe constrain the depth and seismic structure of stiff sediment cover overlying a prospective basement terrane using a passive seismic technique which uses surface wave energy from microtremor also known as ambient seismic energy or seismic noise this may be applied to mineral exploration under cover to decrease the inherent ambiguity in modeling potential field data for exploration targeting we use data from arrays of portable broadband seismometers processed using both the multimode spatially averaged coherency mmspac method and the horizontal to vertical spectral ratio hvsr method to produce profiles of seismic velocity structure along a 12 km transect we have developed field protocols to ensure consistent acquisition of high quality data in near mine and remote locations and a variety of ground conditions a wavefield approaching the theoretical ideal for mmspac processing is created by combining the energy content of an off road vehicle driven around the seismometer array and ambi

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

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

integrated three dimensional interpretation of major concealed faults beneath mapleton utah county utah using gravity data supported with magnetic data abstract gravity and magnetic surveys were conducted to locate major concealed faults beneath mapleton utah county utah a developing city along the wasatch front 80 km south of salt lake city utah although the magnetic data are not as useful for this study due to cultural magnetic noise and logistical limitations in acquiring dense data sets these data do play a backup role in supporting the gravity data by helping to constrain the interpreted models of the major concealed faults data were collected at 196 stations and were processed using conventional techniques regional trends were calculated using trend analysis and residual data were modeled using self consistent iterative modeling ambiguities in the subsurface models were reduced by 1 incorporating data from previous geophysical surveys surface mapping trench studies aerial photos well data and earthquake data 2 integrating the gravity and magnetic data and 3 correlating the modeled cross sections along numerous selected profiles the modeled profiles and integrated three dimensional interpretation indicate that there are four major fault blocks beneath the mapleton area these fault blocks are bounded by a series of west dipping synthetic listric faults depths to the fault blocks range from

contemporary deformation of the wasatch fault utah from gps measurements with implications for interseismic fault behavior and earthquake hazard observations and kinematic analysis 1 contemporary strain accumulation rates of the 350 km long wasatch fault utah have been determined by gps measurements and provide key data for evaluating normal fault behavior and related earthquake hazard assessment this paper presents a complete description of the wasatch gps network data archiving and processing and the measured ground deformation the network spans the wasatch fault in an area 300 km long and 200 km wide in north and central utah and consists of 43 gps sites surveyed in 1992 1993 1994 1995 1999 2001 and 2003 plus 8 permanent gps stations operating continuously beginning 1997 observations across a 65 km wide area centered on the wasatch fault indicate the principal horizontal extension rate of 24 6 nstrain yr with the direction nearly perpendicular to the fault this strain rate corresponds to a horizontal displacement rate of 1 6 0 4 mm yr accommodating 50 of the crustal deformation across the 200 km wide eastern basin range analysis of the spatial variation of the strain rate field reveals that the strain accumulation is concentrated near the wasatch fault which suggests an abrupt transition in the horizontal deformation at the fault between the eastern basin range and the rocky mountains we employed a finite strain model that accounts for simple shear deformation of the hanging wall to compare horizontal extension rates measured by gps with vertical fault displacement rates determined by geologic data our results suggest that the average holocene strain release rate is higher than the contemporary strain loading rate for the wasatch fault if the fault dips less than 30 w but these two rates are consistent if the fault dips more steeply

the record of periadriatic volcanism in the eastern alpine molasse zone and its palaeogeographic implications precise provenance analysis of andesite and dacite pebbles from conglomerates in the eastern alpine molasse zone using geochemical and geochronological methods provides evidence for a synorogenic volcanic chain in the eastern alps which is completely eroded today this volcanism was related to periadriatic magmatism along the periadriatic lineament and took place in the palaeogene roughly between 40 and 30 ma the occurrence of remnants of these volcanic rocks together with other marker lithologies in the eastern alpine molasse implies an early to middle miocene drainage system which was in some respects similar to the present inn river system but had a considerably larger catchment area reaching farther south the palaeo inn drained the central and eastern sections of the periadriatic magmatic belt to the northern foreland basin

fault propagation folding in extensional settings examples of structural style and synrift sedimentary response from the suez rift sinai egypt field data from the oligocene miocene gulf of suez rift demonstrate that coeval growth faults folds and transfer zones exerted a major control on synrift stratigraphic sequence development growth folds in the suez rift are related to steeply dipping normal faults that propagated upward resulting in broad upward widening monoclines in overlying strata folding during fault propagation was accommodated by layer parallel slip and detachment along mudstone horizons as well as by normal and rare reverse secondary faults that propagated away from the master fault the eventual propagation of the master fault through to the surface left the steep limb of the monocline and most of the secondary faults in the hanging wall this evolving structural style exerted a marked control on the geometry and stacking patterns of coeval synrift sediments synrift sediments display onlap and intraformational unconformities toward the growth monoclines and buried faults whereas they diverge into broadly synclinal expanded sections away from the growth monocline continued movement across buried faults resulted in the progressive rotation of the monoclinal limb and associated synrift sediments each successively younger sequence dipping basinward at a shallower angle than the previous one the resulting synrift geometries differ significantly from stratal geometries normally anticipated adjacent to normal faults along strike variations in facies stacking patterns are also commonly associated with decreasing displacement across faults and associated folds toward low relief transfer zones data from other rift basins indicate that fault propagation folds are not unique to the gulf of suez

analyzing shallow faulting at a site in the wasatch fault zone utah usa by integrating seismic gravity magnetic and trench data abstract gravity magnetic and seismic surveys were conducted across the wasatch fault zone east of springville utah near the mouth of hobble creek canyon the geophysical data were acquired processed and interpreted to determine possible locations of larger total offset greater than 6 ft 1 8 m shallow normal faults within the fault zone interpretations of the individual data sets were integrated to help eliminate spurious readings and to strengthen the interpretations visual methods of integration along with computer modeling were chosen for this study furthermore the geophysical data were correlated and integrated with available trench data and surface data in addition to verifying locations of known faults the geophysical surveys detected numerous possible additional faults not previously mapped of particular interest is a newly discovered graben structure near the southern end of the site where building of new homes has recently been proposed new structural information about fault densities and styles was also determined from the surveys the fault concentration for this site is 1 3 faults 100 ft 30 5 m or one fault per 77 ft 23 5 m interpreted antithetic faults at the hobble creek site account for 65 of the total while synthetic faults account for 35 with respect to the main fault strand information derived from this study should be useful during planning and development of areas within the wasatch fault zone the characteristics of subsurface deformation can be used to gain a better understanding of the potential for surface rupture at a given site this is also useful in planning appropriate site development and remedial measures to help mitigate hazards associated with large magnitude earthquakes

noise attenuation by vibroseis whitening vsw processing reflection seismic data recorded on the atlantic coastal plain to examine suspected faulting of the shallow 200 m basement were contaminated by severe ground roll noise with an apparent velocity of 587 m sec 25 hz dominant frequency and 23 m apparent wavelength a receiver interval of 5 m and a total spread length of 285 m were used to obtain 24 fold coverage although the noise problem was severe overlapping source and or receiver arrays on the surface were not used for the recording geometry in order to avoid a decrease in resolution caused by the smoothing effect of overlapping subsurface coverage instead the large amplitude surface waves were attenuated by a process called vibroseis whitening vsw vsw is based on the application of time varying amplitude scaling before vibroseis crosscorrelation a conventional method of automatic digital gain control was found to be effective for this purpose this scaling results in a signal to noise ratio improvement equal to the gain expected from crossc

post collisional orogen parallel large scale extension in the eastern alps abstract large scale extension affected the eastern alps during post collisional lateral tectonic extrusion in early and middle miocene times the tauern window was mainly tectonically exhumed by the 160 km pullapart of the rigidly behaving austroalpine basement blocks forming the tectonic lid of the penninic contents of the window an evaluation of the syn extrusion fault pattern reveals displacements of several tens of kilometers along the low angle extensional shear zones at the western and eastern margins of the window and along the important strike slip fault zones north and south of the window large scale shear is reflected by discontinuities in mineral cooling patterns across important shear zones the cooling histories of the tectonic blocks show that the window boundaries during exhumation coincide only partly with the classical boundaries of the window defined by thrust units reconstruction of the exhumation history shows an asymmetric evolution of the tauern window we argue that the eastern and western low angle extensional shear zones formed in sequence which is reflected by different evolutions of the fragmentation and uplift history of the austraolpine tectonic blocks to the east and west of the window in the central and eastern alps three structural domes the lepontin dome in the central alps and the tauern and rechnitz domes in the eastern alps were formed by large scale extension in miocene times total e w stretch amounts to more than 300 km and results in 70 extension we propose that the central and eastern alps are part of an extensional province that also includes the pannonian basin and has a counterpart separated by the moesian indenter in the rhodope mountains the aegean sea and the menderes massif in asia minor in these regions a number of mainly tectonically exhumed domes or deep sedimentary basins formed by miocene large scale extension

two dimensional thermal modelling of normal faulting the simplon fault zone central alps switzerland abstract two dimensional finite difference thermal modelling of the major extensional simplon fault zone in the central alps establishes that the shape of cooling curves for samples from the footwall and hanging wall at various distances from the detachment are very sensitive to the actual displacement history if the displacement had occurred within a very limited time span 18 15 ma samples from the hanging wall close to the detachment should have significantly increased in temperature with a peak around 14 ma this is not discernible in the cooling curves interpreted from the mineral ages if the rate of normal fault displacement had been lower but constant from 18 ma to present the cooling curves for the footwall should show a correspondingly steady decrease in temperature the interpreted cooling curves from mineral ages are steep after 18 ma becoming shallower in more recent times this shape can be reproduced by the thermal modelling for a variable rate of fault displacement initially rapid total relative displacement 10 mm a across the fault zone between 18 and 15 ma but reducing to a more steady 0 4 mm a between 15 ma and 3 ma the corresponding exhumation rate of the footwall was 4 6 mm a from 18 to 15 ma and 0 6 mm a from 15 to 3 ma whereas the hanging wall was exhumed at a constant rate of 0 4 mm a the difference in cooling curves for samples with increasing horizontal distance into the footwall reflects a distributed ductile shear with the sample at 20 km distance initially at 25 km depth at 25 ma whereas that at 70 m distance was only at 19 km depth at the same time samples in the hanging wall were at 10 km depth total relative displacement parallel to the fault plane was around 36 km the thermal modelling demonstrates that during rapid fault displacement the apparent exhumation rate calculated assuming a constant geothermal gradient is too low whereas the apparent rate calculated for the subsequent period of slower displacement is too high

exhumation of the rechnitz window at the border of the eastern alps and pannonian basin during neogene extension abstract the rechnitz window is the easternmost penninic window of the alps and the only one that is partly covered by neogene sediments zircon and apatite fission track ages have been measured on the penninic metasediments of the rechnitz series to better understand the exhumation of the window at the alpine pannonian border the zircon ft ages range from 21 9 to 13 4 ma similar to the white mica k ar ages 19 and 23 ma the exhumation rate during the early miocene extension was high 40 c ma apatite samples display ft ages of 7 3 and 9 7 ma thus the cooling rate was significantly less 7 11 c ma during the post rift uplift uplift in late miocene pliocene than in the early miocene escape period zircon ft ages decrease eastward due to the gradual southeastward slide of the austroalpine cover along low angle normal faults the exhumation of the rechnitz metamorphic core complex is younger than the unroofing of the eastern tauern window morphology of detrital zircon crystals of the penninic metasediments was used for the differentiation of tectonic subunits and to trace the internal structure of the window one population was probably derived from undifferentiated calc alkaline granitoids and tholeiitic granitoid sources while the other derived from evolved calc alkaline granitoids and alkaline granitoids of anorogenic complexes the areal distribution of zircon populations is in harmony with the eastward shift of zircon cooling ages these data indicate the exhumation of deep levels of penninic metasediments in the centre of the window

on bias and noise in passive seismic data from finite circular array data processed using spac methods the finite nature of typical small seismic arrays used in conjunction with spatial autocorrelation spac processing for observing the microtremor wavefield causes predictable perturbationsofthespacspectrumwhensourcesofseismic noiseareconfinedtoarestrictedrangeofazimuths suchperturbations are especially evident at higher frequencies where wavelengths are on the order of the array radius the effects arereadilymodeledandshowthatthetriangulararraygeometries commonly used for microtremor studies require azimuthal distributions of wave energy on the order of 60 or greatertohaveahighprobabilityofbeingfreeofsuchperturbations the imaginary component of the spac spectrum which is ideally zero for a sufficiently dense circular array and or a sufficiently isotropic wavefield is in practice often nonzero and provides three quality control indicators 1 an indication of insufficient spatial averaging 2 an empirical measure of the level of statistical uncertainty in spac spectralestimates and3anindicationofdeparturesfromplanewavestationarityoftheseismicnoisewavefield

colluvial wedge imaging using traveltime and waveform tomography along the wasatch fault near mapleton utah summary four high resolution seismic surveys were conducted across the wasatch fault zone near mapleton utah the objective was twofold 1 to use velocity tomograms and reflection images to delineate fault structures and colluvial wedges to more than twice the depth of the mapleton megatrench excavated by urs personnel 2 to assess the strengths and limitations of traveltime and waveform tomography by synthetic studies and comparison of the tomogram to the ground truth seen in the megatrench log four out of the five faults within the trench area are accurately identified in the migrated image and in the tomograms and the main fault s dip angle is estimated to be between 71 and 80 two additional faults are interpreted outside the trench the faults can be delineated down to 30 m below the surface which is 20 m deeper than the excavated trench five out of six colluvial wedges found in the trench log were seen as low velocity zones lvzs in the tomogram however the biggest colluvial wedge could not be identified by either tomography method waveform tomography prevailed over ray based traveltime tomography by more clearly recovering the faults and lvzs a newly discovered lvz at a depth of 18 21 m below the surface possibly represents a colluvial wedge and is estimated to be less than 21 000 years old if this lvz is a colluvial wedge the earthquake history obtained by trenching can be extended from 13 500 to 21 000 yr with seismic tomography our results further demonstrate the capability of tomography in identifying faults and show that waveform tomography more accurately resolves colluvial wedges compared to traveltime tomography however despite the successful recovery of most faults and some but not all colluvial wedges both tomography methods show many more lvzs besides the wedges so that an unambiguous interpretation cannot be made a major part of the ambiguity in the tomograms is due to the many major faults which result in an uneven raypath coverage as our synthetic studies show hence seismic trenching will be more successful at simple fault geometries however even under optimal conditions there will be some ambiguity in the interpretation so that detected lvzs should be drilled cored and dated to determine the history of the ancient earthquakes

geometry amount and sequence of thrusting in the subalpine molasse of western austria and southern germany european alps in this paper we review the structure of the most external thrust belt of the alps between the rhein valley and salzburg based on a new tectonic map and the re interpretation of seismic sections specifically we address the correlation between deformation in the subalpine molasse and the alpine thrust belt in general and focus on the control of sedimentary facies on the structural style a dramatic change in architecture from a ramp flat structure to buckle folding is related to a change from coarse grained fans to fine grained deposits within the subalpine molasse additionally the interaction of escape tectonics with postcollisional shortening controls the decrease of late early miocene and younger shortening within the subalpine molasse from 50 km near the rhine valley to almost zero near salzburg transfer of shortening into the hinterland which is the zone of lateral escape ended foreland propagation of the alpine thrusts and initiated a general break back sequence of thrusting throughout this time the thrusts remained active in such a scenario tectonic units on top of the subalpine molasse are expected to undergo clockwise rotation around vertical axes as thrusting in the subalpine molasse is closely related to contemporaneous transport and shortening within the tectonically higher helvetic thrust sheets amounts of miocene differential shortening and related clockwise vertical axis rotation are minimum amounts true clockwise vertical axis rotation is probably larger than the 12 deduced from the subalpine molasse thrust belt

seal bypass at the giant gjallar vent norwegian sea indications for a new phase of fluid venting at a 56 ma old fluid migration system highlights the giant gjallar vent is still active in terms of fluid migration and faulting the base pleistocene unconformity acts as a seal to upward fluid migration seal bypass in at least one location leads to a new phase of fluid venting the giant gjallar vent ggv located in the voring basin off mid norway is one of the largest 5 3 km vent systems in the north atlantic the vent represents a reactivated former hydrothermal system that formed at about 56 ma it is fed by two pipes of 440 m and 480 m diameter that extend from the lower eocene section up to the base pleistocene unconformity bpu previous studies based on 3d seismic data differ in their interpretations of the present activity of the ggv describing the system as buried and as reactivated in the upper pliocene we present a new interpretation of the ggv s reactivation using high resolution 2d seismic and parasound data despite the absence of geochemical and hydroacoustic indications for fluid escape into the water column the ggv appears to be active because of various seismic anomalies which we interpret to indicate the presence of free gas in the subsurface the anomalies are confined to the kai formation beneath the bpu and the overlying naust formation which are interpreted to act as a seal to upward fluid migration the seal is breached by focused fluid migration at one location where an up to 100 m wide chimney like anomaly extends from the bpu up to the seafloor we propose that further overpressure build up in response to sediment loading and continued gas ascent beneath the bpu will eventually lead to large scale seal bypass starting a new phase of venting at the ggv

origin of rollover rollover is the folding of hanging wall fault blocks by bending or collapse in response to slip on nonplanar commonly listric normal faults the shapes of rollover folds are controlled by a number of variables including 1 the shape of the fault 2 the total fault slip after a bed is deposited 3 the direction of relative particle motion in hanging wall collapse 4 the history of sedimentation rate relative to fault slip rate and 5 compaction the importance and role of each of these variables is illustrated by a two dimensional balanced structural modeling technique that treats continuously curved faults as though composed of a large number of straight fault segments in this modeling an active axial surface oriented parallel to the direction of relative p rticle motion in hanging wall collapse emanates from each fault bend and is the instantaneous locus of folding the quantitative correctness of this theory of rollover is tested by modeling natural structures from the gulf of mexico for which both fault shape and fold shape are known from high quality seismic and well sections the direction of hanging wall collapse commonly is in the antithetic or synthetic normal fault or coulomb shear orientations although sliding along weak bedding planes also is an important collapse mechanism in some regions collapse is in the antithetic shear direction for concave fault bends and in the synthetic shear direction for convex bends these collapse directions can be observed directly in some high quality seismic images as axial surfaces emanating from fault bends the shapes of rollovers within growth strata depend strongly on the sedimentation rate relative to fault slip rate as well as the total slip after a bed is deposited the crests of classic gulf coast rollovers are growth axial surfaces along which are abrupt changes in sedimentation rate within the growth st atigraphic interval these changes are produced by deformation of the sediment water interface along active axial surfaces compaction can substantially modify the relationship between fault shape and rollover shape however under certain common conditions the history of compaction can be neglected if the folding is modeled in the compacted state

exhumation of the central alps evidence from 40ar 39ar laserprobe dating of detrital white micas from the swiss molasse basin 40ar 39ar single grain laserprobe dating of detrital white micas from early oligocene to middle miocene 31 14 ma sedimentary rocks of the central swiss molasse basin reveals three distinct clusters of cooling ages for the hinterland two palaeozoic age clusters reflect cooling after the variscan orogeny with only limited reheating during the alpine orogeny the third tertiary age cluster reflecting late alpine cooling is restricted to sediments younger than 20 myr old micas with cooling ages 30 myr are interpreted to originate from the footwall of the simplon detachment fault thus representing formerly exposed upper levels of the present day lepontine metamorphic dome erosion of these levels is reflected by an increase of low grade metamorphic lithic grains in the sandstones this interpretation puts constraints on the timing of exhumation as well as on the evolution of the drainage pattern of the central alps

geometric models of listric normal faults and rollover folds existing geometric models allow master fault shapes to be constructed given the shape and heave or displacement of a deformed marker horizon in the hanging wall these models assist in projecting normal faults to depth where the fault geometry is poorly constrained by available seismic data currently it is unclear which model best predicts the actual relation between rollover and fault geometries to address this deficiency the relative accuracies of the constant heave constant displacement constant bed length slip line and inclined shear constructions are evaluated using clay model analogs and seismic examples each of the geometric models predicts a different fault shape and depth to detachment for the same rollover shape because different hanging wall deformat on mechanisms are assumed a construction is developed for determining the hanging wall geometry from a known fault geometry this construction is based on the inclined shear model and geometric constraints imposed by material displacement paths viewed from different reference frames fixed to the hanging wall and footwall blocks in clay models the inclined shear antithetic shear greek alpha 20 degrees and slip line constructions produce the best agreement between actual and modeled fault and marker bed shapes in rollovers for subsurface examples the inclined shear model antithetic shear greek alpha 20 40 degrees and the constant displacement model predict fault trajectories that are the most similar to the positions and shapes of the master fault segments interpreted fr m offshore norway and gulf of mexico seismic lines the shear angle required in the inclined shear model can often be estimated from the orientation of minor faults in the hanging wall the shear angle may also be determined through iterative modeling in which the shear angle is systematically varied and the resultant model fault shape is compared to the shape of the shallow segment of the master fault interpreted from the seismic record

facies development along the tide influenced shelf of the burdigalian seaway an example from the ottnangian stratotype early miocene middle burdigalian abstract herein we report quantitative micropaleontological benthic foraminifers dinoflagellate cysts calcareous nannoplankton sedimentological grain size analysis and geophysical background gamma radiation analyses from ottnang schanze the stratotype for the regional ottnangian stage central paratethys lower miocene middle burdigalian the revealed trends in bathymetry primary productivity bottom water oxygenation and water energy allow exemplary insights into the paleoenvironment of the terminal burdigalian seaway several facies of a eutrophic environment are distinguished that reflect a transition from a suboxic outer neritic to upper bathyal towards a better oxygenated middle neritic setting under the influence of storm events and currents a comparison with available data from upper austria and bavaria consistently shows the regressive trend during the late early ottnangian in upper austria the deep water facies from the lower part of the stratotype represents the most distal sediments the upper part together with localities closer to the northern coast records inner to middle neritic environments that are heavily affected by tidal currents the facies distribution results from the progradation of a tide influenced environment along the northern shelf of the north alpine foreland basin heralding the closure of the burdigalian seaway the available age estimate for the stratotype constrains the onset of the regressive phase to 18 ma

geochemistry and geochronology of gneiss pebbles from foreland molasse conglomerates geodynamic and paleogeographic implications for the oligo miocene evolution of the eastern alps abstract gneiss pebbles deposited in foreland fans during the miocene epoch were studied with geochemical and thermochronological methods to reconstruct the paleodrainage evolution of the eastern alps and the geodynamic behavior of the source areas clear discrimination between upper plate austroalpine and lower plate penninic gneiss pebbles was achieved by single pebble paleocooling paths austroalpine gneisses showed highly variable and regionally distinctive paleocooling paths which record variscan to cretaceous rb sr and k ar cooling ages penninic gneisses showed paleogene to lower miocene high temperature rb sr k ar and miocene low temperature zircon and apatite fission track cooling ages cooling rates of penninic gneisses indicate maximum exhumation rates at 17 ma during the climax of lateral tectonic extrusion recording dominance of tectonic unroofing the paleodrainage evolution was characterized by a relatively stable catchment configuration in the western part of the eastern alps wh

time calibration of a pt path from the western tauern window eastern alps the problem of closure temperatures new hornblende k ar and 39ar 40ar and mica rb sr and k ar ages are used to place specific timemarks on a well constrained pressure temperature path for the late alpine metamorphism in the western tauern window after identification of excess 40ar the closure behavior of ar in hornblende is compared with that of sr and ar in phengite and biotite samples were collected in three locations whose maximum temperatures were 570 c zemmgrund 550 c pfitscher joch and 500 540 c landshuter hutte

high resolution seismic profiling reveals faulting associated with the 1934 ms 6 6 hansel valley earthquake utah usa the 1934 ms 6 6 hansel valley utah earthquake produced an 8 km long by 3 km wide zone of north south trending surface deformation in an extensional basin within the easternmost basin and range province less than 0 5 m of purely vertical displacement was measured at the surface although seismologic data suggest mostly strike slip faulting at depth characterization of the origin and kinematics of faulting in the hansel valley earthquake is important to understand how complex fault ruptures accommodate regions of continental extension and transtension here we address three questions 1 how does the 1934 surface rupture compare with faults in the subsurface 2 are the 1934 fault scarps tectonic or secondary features 3 did the 1934 earthquake have components of both strike slip and dip slip motion to address these questions we acquired a 6 6 km long high resolution seismic profile across hansel valley including the 1934 ruptures we observed numerous east and west dipping normal faults that dip 40 70 and offset late quaternary strata from within a few tens of meters of the surface down to a depth of 1 km spatial correspondence between the 1934 surface ruptures and subsurface faults suggests that ruptures associated with the earthquake are of tectonic origin our data clearly show complex basin faulting that is most consistent with transtensional tectonics although the kinematics of the 1934 earthquake remain underconstrained we interpret the disagreement between surface normal and subsurface strike slip kinematics as due to slip partitioning during fault propagation and to the effect of preexisting structural complexities we infer that the 1934 earthquake occurred along an 3 km wide off fault damage zone characterized by distributed deformation along small displacement faults that may be alternatively activated during different earthquake episodes

site characterization for urban seismic hazards in lower manhattan new york city from microtremor array analysis 1 we characterize the shear wave velocity vs of soil deposits in lower manhattan at six sites using the spac and hvsr microtremor methods the soil vs ranges from 140 m s to 300 m s over bedrock we believe that bedrock depth is constrained to 15 with these microtremor data but an accurate quantification of bedrock vs is unattainable because of low spectral coherency at frequencies below 3 hz hvsr data corroborate the spac microtremor results at sites based on good alignment of theoretical rayleigh ellipticity peaks 1d sh amplifications and peak hvsr resonant frequencies vary between 1 4 and 5 5 hz between the sites from both observed hvsr and predicted 1d sh amplification shear wave velocities to 30 m classify the sites as c d or e this study demonstrates that given relatively shallow bedrock depth the spac method can work in extremely urbanized areas

shallow subsurface structure of the wasatch fault provo segment utah from integrated compressional and shear wave seismic reflection profiles with implications for fault structure and development integrated vibroseis compressional and experimental hammer source shear wave seismic reflection profiles across the provo segment of the wasatch fault zone in utah reveal near surface and shallow bedrock structures caused by geologically recent deformation combining information from the seismic surveys geologic mapping terrain analysis and previous seismic first arrival modeling provides a well constrained cross section of the upper 500 m of the subsurface faults are mapped from the surface through shallow poorly consolidated deltaic sediments and cutting through a rigid bedrock surface the new seismic data are used to test hypotheses on changing fault orientation with depth the number of subsidiary faults within the fault zone and the width of the fault zone and the utility of integrating separate elastic methods to provide information on a complex structural zone although previous surface mapping has indicated only a few faults the seismic section shows a wider and more complex deformation zone with both synthetic and antithetic normal faults our study demonstrates the usefulness of a combined shallow and deeper penetrating geophysical survey integrated with detailed geologic mapping to constrain subsurface fault structure due to the complexity of the fault zone accurate seismic velocity information is essential and was obtained from a first break tomography model the new constraints on fault geometry can be used to refine estimates of vertical versus lateral tectonic movements and to improve seismic hazard assessment along the wasatch fault through an urban area we suggest that earthquake hazard assessments made without seismic reflection imaging may be biased by the previous mapping of too few faults

variability of apatite fission track annealing kinetics ii crystallographic orientation effects a method is presented that permits the length of any horizontal confined fission track inclined at a specified angle to the crystallographic c axis in apatite to be converted to an equivalent track length parallel to the crystallographic c axis the model is based on the results of annealing experiments for six selected apatites five calcian fluorapatites and durango apatite representing a subset of the 15 total apatite specimens studied an iterative process of calculation is required to project fission track lengths onto the c axis and computer source code implementing the solution to this problem is presented this method of projecting apatite fission track lengths onto the crystallographic c axis is shown to remove effectively fission track length variation within single fission track populations due to anisotropic track length reduction for all 15 apatites studied in addition a model is developed that offers predictions that closely reproduce published experimental data concerning the relationship between fission track density etched fission tracks per unit area of apatite surface and the arithmetic mean fission track length finally it is shown that natural fission track populations exhibit fission track length anisotropy similar to that of fission track populations created and annealed in the laboratory this observation implies that the same process by which apatite fission tracks anneal in the laboratory is responsible for annealing of apatite fission tracks in the geological environment

quantifying tectonic versus erosive denudation by the sediment budget the miocene core complexes of the alps abstract the denudation budget of the alps is quantified for the main period of lateral extrusion between 22 and 12 ma the relative importance of tectonic denudation increases from w to e from 70 in the lepontine window in the swiss alps to 80 in the tauern window and to more than 95 in the rechnitz window the driving mechanism of tectonic denudation was eastward extrusion due to an unconstrained orogenic margin in the pannonian basin tectonic denudation in the alps was responsible for about 30 of the total exhumation between 22 and 12 ma

depositional and structural evolution of a foreland basin margin in a magnetostratigraphic framework the eastern swiss molasse basin this integrated study of the sedimentology magnetostratigraphic chronology and petrography of the mostly continental clastics of the oligocene to miocene swiss molasse basin underpins a reconstruction of facies architecture and delineates relationships between the depositional evolution of a foreland basin margin and exhumation phases and orogenic events in the adjacent orogen a biostratigraphically based high resolution magnetostratigraphy provides a detailed temporal framework and covers nearly the whole stratigraphic record of the molasse basin 31 5 13 ma three transverse alluvial fan systems evolved at the southern basin margin they are characterized by distinct petrographic compositions and document the exhumation and denudation history of the growing eastern swiss alps enhanced northward propagation of the orogenic wedge is interpreted to have occurred between 31 5 and 26 ma during the period 24 19 ma intense in sequence and out of sequence thrusting took place as molasse strata were accreted to the orogenic wedge a third active tectonic phase possibly caused by backthrusting of the plateau molasse probably occurred between ca 15 and 13 ma fan head migration between 31 5 and 13 ma is probably controlled by the structural evolution of the thrust front due to molasse accretion and backthrusting

mineralized and unmineralized calderas in spain part ii evolution of the rodalquilar caldera complex and associated gold alunite deposits the rodalquilar caldera complex is located in the western part of the cabo de gata volcanic field in southeastern spain and is the first documented example of epithermal gold alunite mineralization within a caldera in europe the rodalquilar caldera is an oval collapse structure having a maximum diameter of 8 km and formed at 11 ma from eruption of the cinto ash flow tuff the oval lomilla caldera with a diameter of 2 km is nested within the central resurgent dome of the older rodalquilar caldera the lomilla caldera resulted from the eruption of the lazaras ash flow tuff which was ponded within the moat of the rodalquilar caldera the last phase of volcanic activity in the caldera complex was the emplacement of hornblende andesite flows and intru sions this magmatic event resulted in structural doming of the caldera opening of fractures and faults and pro vided the heat source for the large hydrothermal systems which deposited quartz alunite type gold deposits and base metal vein systems the gold alunite deposits are enclosed in areas of intense acid sulfate alteration and localized in ring and radial faults and fractures present in the east wall of the lomilla caldera like other acid sul fate type deposits the rodalquilar gold alunite deposits are closely related in time and space to porphyritic inter mediate composition magma emplaced along caldera structures but unrelated to the caldera forming magmatic system

early burdigalian infill of the puchkirchen trough north alpine foreland basin central paratethys facies development and sequence stratigraphy abstract to improve the prediction of gas and oil in strata along the tectonically imbricated southern margin of the puchkirchen trough north alpine foreland basin central paratethys a better understanding of facies distribution and stratigraphic control of the basin is essential the present study provides bio and chemofacies analyses and a biostratigraphic evaluation for the pelitic hall formation from the borehole hochburg 1 in the central part of the puchkirchen trough a statistical evaluation of benthic foraminiferal assemblages together with geochemical proxy records toc sulphur hydrogen index 13 c toc 15 n tn reveals a succession of early burdigalian depositional environments following a major subaqueous erosional hiatus conglomeratic sands at the base of the section which contain reworked chattian and aquitanian foraminiferal assemblages record the reactivation of a basin axial channel system during the early burdigalian eustatic sea level rise the channel was cut off from its sediment sources on the shelf and a deepening bathyal environment was established agglutinated foraminiferal assemblages with abundant bathysiphon filiformis developed that were adapted to an unstable environment with frequent deposition of turbidites the middle part of the hall formation is characterized by prograding high relief clinoforms which are fed by the wachtberg delta of the paleo inn river high sedimentation rates are interpreted and increased input of terrestrial derived organic matter is documented with a strong correlation of toc and toc s and low hi values as well as frequent occurrences of ammodiscus spp and other opportunistic agglutinating foraminifers a renewed transgression reestablished a eutrophic and suboxic bathyal environment followed by the development of an oxygenated outer middle neritic shelf environment heralding the ultimate infill of the deep water basin based on a comparison of the revealed development to existing sequence stratigraphic models for the puchkirchen trough three sequences and their corresponding systems tracts can be identified for the lower middle and upper hall formation biostratigraphic evidence from benthic foraminifers and calcareous nannoplankton indicates that they correspond to the regional substages of the middle and upper eggenburgian and lower ottnangian and to global 3rd order sequences bur 1 3 the observations suggest a primary control of eustatic sea level on the puchkirchen trough rather than alpine tectonics during the burdigalian

characterization of intrabasin faulting and deformation for earthquake hazards in southern utah valley utah from high resolution seismic imaging we conducted active and passive seismic imaging investigations along a 5 6 km long east west transect ending at the mapped trace of the wasatch fault in southern utah valley using two dimensional 2d p wave seismic reflection data we imaged basin deformation and faulting to a depth of 1 4 km and developed a detailed interval velocity model for prestack depth migration and 2d ground motion simulations passive source microtremor data acquired at two sites along the seismic reflection transect resolve s wave velocities of approximately 200 m s at the surface to about 900 m s at 160 m depth and confirm a substantial thickening of low velocity material westward into the valley from the p wave reflection profile we interpret shallow 100 600 m bedrock deformation extending from the surface trace of the wasatch fault to roughly 1 5 km west into the valley the bedrock deformation is caused by multiple interpreted fault splays displacing fault blocks downward to the west of the range front further west in the valley the p wave data reveal subhorizontal horizons from approximately 90 to 900 m depth that vary in thickness and whose dip increases with depth eastward toward the wasatch fault another inferred fault about 4 km west of the mapped wasatch fault displaces horizons within the valley to as shallow as 100 m depth the overall deformational pattern imaged in our data is consistent with the wasatch fault migrating eastward through time and with the abandonment of earlier synextensional faults as part of the evolution of an inferred 20 km wide half graben structure within utah valley finite difference 2d modeling suggests the imaged subsurface basin geometry can cause fourfold variation in peak ground velocity over distances of 300 m

s wave velocity profiling by joint inversion of microtremor dispersion curve and horizontal to vertical h v spectrum a joint inverse analysis using both microtremor dispersion curve and horizontal to vertical h v spectrum is proposed for estimating the s wave velocity vs profiles of subsurface soils in the inversion both microtremor dispersion and h v data are assumed to be the rayleigh wave dispersion curve and the surface both rayleigh and love wave h v spectrum that have been theoretically derived by taking into account the effects of their fundamental and higher modes the proposed joint inversion as well as the conventional one using dispersion data alone is per formed at four sites where shallow vs profiles down to engineering bedrock are available the vs profiles estimated by the proposed joint inversion are more con sistent with available down hole velocity logs than those by the conventional method in particular the proposed inversion shows significant improvement in estimating bedrock vs structures compared to the conventional inversion sensitivity analyses indicate that the surface wave h v ratio is sensitive to the bedrock vs structure more than the rayleigh wave phase velocity confirming that the proposed joint inversion including h v spectrum is promising

the erosion history of the central alps evidence from zircon fission track data of the foreland basin sediments fission track dating on detrital zircons of alpine debris in the swiss molasse basin provides information about the erosion history of the central alps and the thermal evolution of source terrains during oligocene times only sedimentary cover nappes and austroalpine basement units were eroded incision into austroalpine basement units is indicated by increasing importance of cretaceous cooling ages in granite pebbles upsection erosion of penninic basement units started between 25 and 20 ma early oligocene zircon ft ages show that penninic basement units were exposed at 20 ma deeper penninic units of the lepontine dome became exposed first at 14 ma contemporaneously with the opening of the tauern window in the eastern alps a middle miocene cooling rate of 40 c myr 1 is deduced for the lower penninic units of the lepontine dome

role of topography in isotherm perturbation apatite u th he and fission track results from the malta tunnel tauern window austria 1 apatite u th he and fission track age determinations of samples from a 20 km long near horizontal tunnel in the hochalm ankogel dome eastern tauern window austria are presented in order to determine the role of paleo topography in perturbing isotherms in the shallow crust apatite fission track ages 26 8 ma show no systematic correlation with distance along the tunnel or elevation two age components in the fission track data indicate cooling through 120 c at approximately 20 ma and 80 c at approximately 6 ma surface and tunnel u th he ages 17 9 ma and 13 5 ma respectively are consistently younger than the equivalent fission track ages u th he ages vary systematically along the tunnel with older ages at the northern and southern tunnel portals and younger ages in the central section geological factors faulting lithology appear to have had little effect on this age distribution the u th he age pattern is inconsistent with rock cooling underneath the present day hochalm ankogel dome topography the age minimum is interpreted to coincide with a paleotopographic maximum in the hochalm ankogel dome and suggests that the 40 60 c isotherms were warped sufficiently to affect apatite u th he ages the tunnel apatite u th he ages match synthetic he ages derived from a two dimensional numerical model of landscape evolution integrating the thermal model results with the data allows the relief development to be constrained and we calculate that the present day hochalm ankogel dome topography was formed at 7 to 10 ma

paleogeography and catchment evolution in a mobile orogenic belt the central alps in oligo miocene times abstract in this study we reconstruct the surface evolution of the oligo miocene central alps using geochronological geochemical and petrographical methods on the foreland basin sediments of both flanks of the mountain range our model is illustrated in four sketch maps of different time slices between mid oligocene to middle miocene times for each time slice we try to 1 give a palinspastic reconstruction of the central alps based on the post collisional lateral extrusion model 2 show which tectonic units had become exposed to the surface due to exhumation processes in the central alps 3 describe the thermochronologic evolution of lithological units formerly exposed but completely eroded today 4 differentiate the catchment areas of the paleo river systems which delivered debris to the foreland basins and 5 describe the position of the main drainage divide relative to the exposed tectonic units