patterns of imbricate thrusting through the use of seismic reflection profiles satellite images and balanced kinematic models we describe patterns that help to identify imbricate structures and define the sequence of thrusting in fold and thrust belts measures of folding shear strains are employed to define break forward systems in which younger deeper faults refold overlying thrust sheets in contrast break backward sequences form a wide range of viable geometries that are not expected to conserve these folding strains thus measures of folding shear strains provide a means to define thrusting sequence we also explore map view patterns of imbricate thrusting by using three dimensional models and stereoscopic satellite images we present an example from the peruvian andes in which these map patterns are combined with seismic reflection profiles to define a complex imbricate system with components of both break forward and break backward thrusting these integrated methods provide new tools for understanding the deformational histories of fold and thrust belts including the definition of complex structural closures with opportunities for hydrocarbon reservoir duplication

duplex style and triangle zone formation insights from physical modeling duplexes are a common feature in thrust belts at many scales their geometries vary significantly from antiformal stacks with significant forethrusting in the cover e g southern pyrennes spain to triangle zones e g foreland canadian rockies to low displacement individually spaced ramp anticlines e g sub andean thrust belt bolivia we present a series of physical experiments demonstrating that the strength of the decollements relative to that of the intervening and overlying rock layers plays a significant role in controlling the duplex style the models comprise brittle layers made of dry quartz sand and decollements made of two types of viscous silicone polymers the strength of the decollements in the models is a function of the shortening rate applied to the model the relative strength of the decollements and surrounding rocks affects the development of active or passive roof duplexes triangle zones it also affects the amount of translation of individual thrust blocks and the spacing of thrust ramps which in turn determine if a duplex evolves into an antiformal stack or into individually spaced ramp anticlines model results indicate that specific associations of structural features form systematically under similar rheological and boundary conditions the presence of relatively strong decollements promotes local underthrusting of the cover individual ramp anticlines internal deformation of thrust sheets low early layer parallel shortening and sequential towards the foreland propagation of structures weak decollements promote forethrusting of the cover antiformal stacks coeval growth of structures and low internal strain with the exception of significant early layer parallel shortening no underthrusting at a regional scale occurred in any model

shallow high resolution seismics and reprocessing of industry profiles in southern bavaria the molasse and the northern alpine front abstract the purpose of this seismic investigation in the upper bavarian miesbach area as part of the international transalp project was to study the tectonic contact between the autochthonous foreland molasse and the allochthonous folded molasse marking the tectonic front of the alpine orogen another specific target was the dip of the frontal emerging main thrust of the tectonic units helveticum ultrahelveticum and rhenodanubian flysch overriding the folded molasse twelve seismic profiles obtained from the hydrocarbon industry were reprocessed from the foreland molasse southward to the autochthonous molasse in the subsurface of the overthrust folded molasse conspicuous features such as steep normal faults at the molasse base s directed thickening of molasse sediments or sedimentary discordant base of upper marine molasse can be recognized shallow high resolution seismic measurements were conducted along two profiles across the tectonic contact between foreland molasse and folded molasse as well as along a profile across the frontal emerging main thrust of the helveticum ultrahelveticum and the rhenodanubian flysch geological structures could be identified in the top 300 500 ms two way traveltime interval which is hardly possible with the usual deep seismic method the method thus provides a bridge between deep reflection seismics and surface geology in contrast to the western bavarian molasse zone the tectonic boundary between the foreland molasse and the folded molasse in the investigated area is not characterized by a large blind thrust triangle zone but by a simple south dipping thrust plane adjacent to the s follow several steeply south dipping inverse molasse thrust slices and the miesbach syncline the inverse thrust slices are interpreted as the overturned and sheared northern limb of a fault propagation fold which linked the folded molasse to the foreland molasse during a final orogenic phase the main thrust of the helveticum ultrahelveticum and the rhenodanubian flysch are well imaged in the near surface interval of the high resolution reflection seismic data in contrast to previously published results these thrust planes show a gentle dip to the s from the surface down to at least 500 1000 m depth

the formation of pure anorthosite on the moon the giant impact hypothesis for the origin of the moon points to the creation of a hot young moon likely with a global magma ocean such a magma ocean would produce a flotation crust of plagioclase crystals or an anorthositic crust early calculations of the expected anorthosite content of the lunar highlands crust did not match initial measurements of apollo samples and more recently have not matched clementine measurements or selene measurements because they assumed interstitial melt would freeze we consider a physical model of a magma ocean with an accumulating flotation lid and find that significant escape of melt can take place for reasonable physical parameters and timescales of melt migration even allowing for the inhibiting effect of plausible compaction viscosities this model permits more nearly pure lunar anorthosites consistent with observations the model encounters some difficulty in explaining the expulsion of melt for the near surface crust up to five kilometers depth that presumably dominates the apollo samples suggesting that impact mixing and tidal heating are needed to explain the discrepancy

acoustic reflections in the water column of krishna godavari offshore basin bay of bengal seismic oceanographic studies from various oceans worldwide have indicated that the acoustic reflections are mostly observed along thermal boundaries within the water column however the authors present a case study of seismic data from krishna godavari basin which shows that salinity variations also play an important role in the occurrence of water column reflections the observed reflection is modeled using the reflectivity series derived from the salinity and temperature profiles from a nearby conductivity temperature depth ctd location sensitivity analysis of temperature and salinity on soundspeed shows that the effect of salinity cannot be ignored for modeling acoustic reflections the synthetic seismogram matches well with the observed reflection seismic data remarkable similarities between the reflection seismic and the salinity profile in the upper thermocline suggest the importance of salinity variations on the water column reflection furthermore impedance inversion of the reflectivity dat

structural elements of the southern tethyan himalaya crust from wide angle seismic data a deep seismic common midpoint cmp profile shot across the southern margin of the tethyan himalaya as the first stage of project international deep profiling of tibet and the himalaya indepth imaged the top main himalayan thrust or mht and bottom moho of the indian continental crust underthrusting the himalaya we used portable seismographs to record the cmp profile shots at a wide range of offsets up to 155 km our short offset data corroborate the cmp profile data while our large offset data are dominated by a band of reflectivity we interpret the bright onset of this reflective band as the basal detachment of the south tibetan detachment system and a phase at the end of the reflective band as the mht we used the cmp profile first break data to model the uppermost 2 km in detail the depth of young extensional basins of the yadong rift system along the cmp profile was constrained to a maximum of 2 km yielding a throw of 4 6 km across the eastern flank of the rift and a rough estimate of approximately 1 5 east west extension by normal faulting in the tethyan himalaya the wide angle data were used to construct a crustal seismic velocity model down to the mht the south tibetan detachment system stds basal detachment reflector is observed dipping 12 5 nne from a depth of about 6 km beneath the surface under the south end of the cmp profile to a depth of 22 km then flattening to a dip of only 2 5 nne thus our observations suggest that the stds basal detachment is a deep rooted basement fault for the mht we observe a dip of 7 5 nne from 20 km depth below sea level at the crest of the high himalaya crystalline sheet to 36 km below sea level 40 km beneath the surface at a distance of about 70 km south of the indus yarlung suture iys from geometrical arguments we suggest that indian crust underthrusts the surface expression of the iys within the crust but does not form the lower crust of central and northern tibet

geometric and seismic interpretation of the perdido fold belt northwestern deep water gulf of mexico we interpret the perdido fold belt to be composed of detachment folds flanked by megascopic scale kink bands the two previous principal fold models for the perdido fold belt incorporated components of large scale faulting an imbricate fault bend fold model and a high angle reverse faulted detachment fold model we interpret the perdido fold belt to be fold dominated the belt consists of detachment folds overlying a ductile decollement layer the detachment fold crests are bounded by kink bands which are narrow zones of angularly folded strata the low reflectivity low signal to noise zones seen in seismic profiles across the perdido fold belt are poorly imaged sections of the folds that result from steeply dipping bedding in the kink bands the substantial width of these low reflectivity zones their subparallel edges in cross section and their orientation at a high angle to layering as well as their organized spacing and conjugate geometry support a kink band interpretation propagating reverse faults are unlikely in the folds because of the absence of backlimbs overlying the locations of hypothetical faults improved seismic imaging efforts have illuminated steeply dipping bedding that is not cut by faulting in many of the low reflectivity zones in the perdido fold belt

simple equations for the speed of sound in neptunian waters two simple equations for the speed of sound in sea waters down to depths of 4 km have been obtained as approximations to a more precise equation developed by lovett the simpler of the two is valid for all neptunian waters except the red sea mediterranean sea and persian gulf and agrees with lovett s equation to within about 0 1 m s the other includes these water masses and is in agreement with lovett to within about 0 03 m s the two equations are well adapted to programmable handheld calculators

shear wave reflection profiling for near surface lignite exploration we present the results of a shear wave reflection experiment and in situ measurements in opencast lignite exploration near surface coal seams have lower shear wave velocities 200 m s and lower densities than sand and clay layers due to strong reflection coefficients a shear wave reflection survey provides a powerful tool in lignite prospecting due to shorter seismic wavelengths shear waves will yield a higher resolution of shallow subsurface structure than compressional waves low shear wave velocities and strong lateral velocity variations however require a dense data acquisition in the field the variation of stacking velocities can exceed 15 within a profile length of 300 m the different steps in processing and interpretation of results are described with actual records the final cmp stack shows steep angle fault zones with maximum dislocations of 20 m within a coal seam

interaction between normal faults and fractures and fault scarp morphology fault slip and geomorphic surface processes create and modify bedrock normal fault scarps our field studies and numerical models show that mechanical interaction between near surface fractures and active faults may diminish scarp slopes and broaden deformation near the surface in our models increasing fracture density and depth reduces and complicates the scarp s topographic expression fracture depth and density and orientation of the structures control the location and magnitude of zones of positive and negative shear displacements along the fractures our field studies of the interaction of active graben bounding normal faults and fractures in northern arizona illustrate the mechanical analysis reduction in scarp slopes and broadening of the deformation field may cause incorrect interpretations of shallow bedrock scarp morphologies as old rather than as the result of slip along fractures around the fault

tectonic style and pressure distribution at the northern margin of the alps between lake constance and the river inn hydrocarbon exploration in the molasse basin and the alpine thrust belt has provided new information on the tectonic structure of the foreland margin of the overthrust belt two n s cross sections show the front of the folded molasse as a so called triangle zone in the area north of the hindelang 1 well bavaria and the sulzberg 1 well vorarlberg the triangle zone was described and defined byjones 1982 for the alberta foothills in canada

integration of p and sh wave high resolution seismic reflection and micro gravity techniques to improve interpretation of shallow subsurface structure new madrid seismic zone abstract shallow high resolution seismic reflection surveys have traditionally been restricted to either compressional p or horizontally polarized shear sh waves in order to produce 2 d images of subsurface structure the northernmost mississippi embayment and coincident new madrid seismic zone nmsz provide an ideal laboratory to study the experimental use of integrating p and sh wave seismic profiles integrated where practicable with micro gravity data in this area the relation between deeper deformation of paleozoic bedrock associated with the formation of the reelfoot rift and nmsz seismicity and shallower deformation of overlying sediments has remained elusive but could be revealed using integrated p and sh wave reflection surface expressions of deformation are almost non existent in this region which makes seismic reflection surveying the only means of detecting structures that are possibly pertinent to seismic hazard assessment since p and sh waves respond differently to the rock and fluid properties and travel at dissimilar speeds the resulting seismic profiles provide complementary views of the subsurface based on different levels of resolution and imaging capability p wave profiles acquired in southwestern illinois and western kentucky usa detect faulting of deep paleozoic bedrock and cretaceous reflectors while coincident sh wave surveys show that this deformation propagates higher into overlying tertiary and quaternary strata forward modeling of micro gravity data acquired along one of the seismic profiles further supports an interpretation of faulting of bedrock and cretaceous strata the integration of the two seismic and the micro gravity methods therefore increases the scope for investigating the relation between the older and younger deformation in an area of critical seismic hazard

topographic slope as a proxy for seismic site conditions and amplification we describe a technique to derive first order site condition maps directly from topographic data for calibration we use global 30 arc sec topographic data and v s 30 measurements here v s 30 refers to the average shear velocity down to 30 m aggregated from several studies in the u s as well as in taiwan italy and australia v s 30 values are correlated against topographic slope to develop two sets of parameters for deriving v s 30 one for active tectonic regions where topographic relief is high and one for stable shields where topography is more subdued by taking the gradient of the topography and choosing ranges of slope that maximize the correlation with shallow shear velocity observations we can recover to first order many of the spatially varying features of sitecondition maps developed for california our site condition map for the low relief mississippi embayment also predicts the bulk of the v s 30 observations in that region despite rather low slope ranges we find that maps derived from the slope of the topography is often well correlated with other independently derived regional scale site condition maps but the latter maps vary in quality and continuity and subsequently also in their ability to match observed v s 30 measurements contained therein alternatively the slope based method provides a simple approach to uniform site condition mapping

restoration of the cretaceous uplift of the harz mountains north germany evidence for the geometry of a thick skinned thrust reverse movement on the harz northern boundary fault was responsible for the late cretaceous uplift of the harz mountains in northern germany using the known geometry of the surface position and dip of the fault and a published cross section of the base permian horizon we show that it is possible to predict the probable shape of the fault at depth down to a detachment level we use the inclined shear method with constant heave and argue that a shear angle of 30 was most likely in this case the detachment level is at a depth of ca 25 km kinematic restoration of the harz mountains using this fault geometry does not produce a flat horizon rather it results in a ca 4 km depression airy heiskanen isostatic equilibrium adjustment of the harz mountains restores the base permian horizon to the horizontal as well as raising the moho to a depth of 32 km a typical value for northern germany restoration also causes a rotation of tectonic fabrics within the harz mountains of about 11 clockwise we show that this model geometry is very good fit to the interpreted dekorp basin 9601 deep seismic profile

source receiver interferometric redatuming using sparse buried receivers to address complex near surface environments a case study of seismic imaging quality and time lapse repeatability

integration of multicomponent time lapse processing and interpretation focus on shear wave splitting analysis multicomponent seismic processing and interpretation have become disconnected in industry practice hindering the ability to extract meaningful reservoir characterization conclusions integrating seismic processing with the final interpretation goals elevates the overall characterization that can be performed and drives advancements in processing algorithms the focus of this study is on converted waves because of their high sensitivity to the azimuthal anisotropy caused by preferential fractures and differential stress and ultimately because they provide a method of correlating hydraulic stimulation success to the enhanced permeability pathways created in the hydraulic completion process

computation of refraction static corrections using first break traveltime differences differences in first arrival traveltimes between adjacent records in multifold reflection surveys can be used to compute the depth and velocity structure of near surface layers the procedure uses the redundancy of first break data in multifold surveys to enable a statistically reliable refraction analysis to be undertaken for either end on or split spread recording geometries the traveltime differences as a function of source receiver offset provide a direct indication of the number of refractors present with each refractor being defined by an offset range with a constant time difference for each refractor the time difference value at a common receiver from two shotpoints is used to partition the intercept time into the delay time at each shotpoint this procedure is repeated until the delay times at all shotpoints and for all refractors have been computed refractor depths and velocities are evaluated from this suite of delay times a surface consistent static correction to a selected datum level is then calculated at each surface station using a replacement velocity equal to that of the deepest refractor in a case history from the canadian rocky mountain foothills short and intermediate wavelength weathering static anomalies were resolved successfully elevation and weathering static corrections of up to 40 ms were computed with an estimated error of less than or 3 ms

a new view of lunar ferroan anorthosites postmagma ocean petrogenesis 1 new melting experiments in the range of 0 1 mpa to 4 7 gpa provide the basis for calculations of polybaric crystallization which show that both a 300 km deep magma ocean mo enriched in refractory elements and a 600 km deep magma ocean with refractory element concentrations similar to the earth s upper mantle produce sufficient amounts of differentiated residual liquid capable of crystallizing the troctolitic noritic mineral assemblages that are prevalent in lunar ferroan anorthosites lfa however the both oceans become saturated with augite after 20 30 crystallization of the plagioclase saturated residuum and thereafter are no longer capable of producing noritic assemblages a second set of melting experiments reveals the existence of a previously unrecognized equilibrium augite liquid pigeonite plagioclase and a thermal minimum on the pigeonite plagioclase liquidus surface at 0 6 gpa these equilibria will produce melts of mafic cumulates with lower wo content than those from which the cumulates originally formed in a postmagma ocean environment of overturning mafic cumulates melt thus formed and entrained in a buoyant segregation of plagioclase would then form diapiric masses that would crystallize troctolitic noritic assemblages after intruding upward diapiric intrusions could also provide the local deformational environment needed to produce the apparently high 95 plagioclase modes of the lfa an unstable density profile in the cumulate pile following crystallization of most of the mo should provide the impetus for overturn and the heat for partially remelting mafic cumulates

seismic interpretation and structural restoration of the heligoland glaciotectonic thrust fault complex implications for multiple deformation during pre elsterian to warthian ice advances into the southern north sea basin abstract despite a long history of research the locations of former ice margins in the north sea basin are still uncertain in this study we present new palaeogeographic reconstructions of pre elsterian and warthian ice margins in the southeastern north sea basin which were previously unknown the reconstructions are based on the integration of palaeo ice flow data derived from glaciotectonic thrusts tunnel valleys and mega scale glacial lineations we focus on a huge glaciotectonic thrust complex located about 10 km north of heligoland and 50 km west of the north frisian coast of schleswig holstein northern germany multi channel high resolution 2d seismic reflection data show a thrust fault complex in the upper 300 ms twt ca 240 m of seismic data this thrust fault complex consists of mainly neogene delta sediments covers an area of 350 km2 and forms part of a large belt of glaciotectonic complexes that stretches from offshore denmark via northern germany to poland the deformation front of the heligoland glaciotectonic complex trends approximately nne ssw the total length of the glaciotectonic thrust complex is approximately 15 km the thrust faults share a common detachment surface located at a depth of 250 300 ms twt 200 240 m below sea level the detachment surface most probably formed at a pronounced rheological boundary between upper miocene fine grained pro delta deposits and coarser grained delta front deposits although we cannot rule out that deep permafrost in the glacier foreland played a role for the location of this detachment surface restored cross sections reveal the shortening of the complex along the detachment to have been on average 23 ranging from ca 16 50 the determined ice movement direction from east southeast to southeast suggests deformation by an ice advance from the baltic region the chronospatial relationship of the thrust fault complex and adjacent northwest southeast to northeast southwest trending elsterian tunnel valleys implies a pre elsterian mis 16 age of the glaciotectonic complex however the age of these elsterian tunnel valleys is poorly constrained and the glaciotectonic complex of heligoland may also have been formed during an early elsterian ice advance into the southeastern north sea basin the glaciotectonic complex underwent further shortening and the elsterian tunnel valley fills that were incised into the glaciotectonic complex were partly deformed during the saalian drenthe and warthe 1 ice advances

simulation of foreland basin stratigraphy using a diffusion model of mountain belt uplift and erosion an example from the central alps switzerland foreland basin stratigraphy can be considered as the result of three interacting processes thrust deformation which builds the tectonic load sedimentary and erosional processes which redistribute that load and the flexural response of the lithosphere the resultant stratigraphy of foreland basins is commonly composed of a small number of shallowing and coarsening upward cycles bounded by regional unconformities to understand the development of these unconformities we present a simple model of these three processes coupling an evolving thrust wedge on a linear elastic plate with erosion and sedimentation defined by the diffusion equation applied to topography our model demonstrates the development of regional unconformities without recourse to either eustasy or complex viscoelastic models for the continental lithosphere the model describes the thrust wedge foreland basin system in terms of four parameters 1 the effective elastic thickness of the foreland plate te 2 the sediment transport coefficient k 3 the thrust wedge advance rate 4 the surface slope of the thrust wedge the model is applied to the oligocene miocene north alpine foreland basin nafb of eastern switzerland the stratigraphy of the nafb can be simplified into two large scale shallowing upward cycles separated by an unconformity at the base of the burdigalian 22 ma geological information is taken from the nafb to estimate suitable values for the parameters listed above assuming a linear elastic lithospheric rheology the te value is estimated at 10 5 km from decompacted sediment columns data to constrain the sequential development of the thrust wedge come from structural geology the early stages 40 24 ma of compression involved a relatively low angle thrust wedge with an advance rate of approximately 2 4 mm yr at about 24 ma the wedge advance slowed down and thickened by underplating crystalline basement of the foreland plate the value for the transport coefficient has been estimated from previous studies prior to attempting to simulate the broad scale geometry of the nafb the role of each parameter was assessed individually the values for te and k are held constant throughout the simulation of the nafb at 7 5 km and 500 m yr respectively the geometry of the base burdigalian unconformity is reproduced by variations in the parameters describing the thrust wedge the surface slope angle of the wedge is increased from 2 5 to 4 over 0 2 m y and the rate of thrust advance is decreased from 2 mm yr to 0 2 mm yr during the thickening event between 24 and 23 8 ma the rejuvenation of the internal parts of the thrust load causes backtilting of the foreland basin sediments and after a time lag erosion of the distal stratigraphy over the forebulge so simulating the base burdigalian unconformity

global occurrence trend of high ca pyroxene on lunar highlands and its implications we present details of the global distribution of high ca pyroxene hcp rich sites in the lunar highlands based on the global data set of hyperspectral reflectance obtained by the selene spectral profiler most hcp rich sites in the lunar highlands are found at fresh impact craters in each crater most of the detection points are distributed on the ejecta rim and floor of the impact craters rather than the central peaks while the central peaks are dominated by purest anorthosite pan this indicates that hcp rich materials originate from relatively shallower regions of the lunar crust than pan in addition while all ray craters with sizes larger than 40 km possess hcp rich materials small fresh craters with sizes less than 6 10 km do not indicating that the uppermost mixing layers in the lunar crust are not dominated by hcp based on these results we propose that in the upper lunar crust a hcp rich zone overlying the pan layer exists below the uppermost mixing layer this hcp rich zone may originate from interstitial melt during the formation of the flotation anorthositic cumulate while an impact ejecta origin impact melt origin and or magmatic intrusion into the upper lunar crust may also account for the occurrence of hcp rich sites in the highlands

featureless spectra on the moon as evidence of residual lunar primordial crust we report the global distribution of areas exhibiting no absorption features featureless or fl on the lunar surface based on the reflectance spectral data set obtained by the spectral profiler onboard kaguya selene we found that fl sites are located in impact basins and large impact craters in the feldspathic highlands terrane while there are no fl sites in the procellarum regions nor the south pole aitken basin fl sites in each impact basin crater are mainly found at the peak rings or rims where the purest anorthosite pan sites are also found at the local scale most of the fl and pan points are associated with impact craters and peaks most of the fl spectra show a steeper redder continuum than the pan spectra suggesting the occurrence of space weathering effects we propose that most of the material exhibiting a fl spectrum originate from space weathered pan taking into account all the occurrence trends of fl sites on the moon we propose that both the fl and pan materials were excavated from the primordial lunar crust during ancient basin formations below the megaregolith in the highlands since the fl and pan sites are widely distributed over the lunar surface our new data may support the existence of a massive pan layer below the lunar surface

estimation of sea surface temperature sst using marine seismic data not much attention is given to direct wave arrivals in marine seismic data that are acquired for petroleum exploration and prospecting these direct arrivals are usually muted out in routine seismic data processing in the present study we process these direct arrivals to accurately estimate soundspeed in near surface seawater and invert for sea surface temperature the established empirical equation describing the relationships among temperature salinity pressure and soundspeed is used for the inversion we also discuss processing techniques such as first break picking and cross correlation for the estimation of soundspeed that are well known among petroleum industry geophysicists the accuracy of the methods is directly linked to the data quality and signal processing the novelty in our approach is in the data conditioning which consists essentially of spectral balancing based on a wavelet transform that compensates for spherical spreading and increases the signal to noise s n ratio the 2d seismic data used in this paper are from the offshore krishna godavari basin east of india we observe a significantly higher soundspeed of 1545 m s for near surface water than the commonly used value of 1500 m s the estimated temperature from velocity is about 30 c interestingly the estimated temperature matches well with the temperature recorded in the ctd profile acquired in the study area during the month of may the month corresponding to the acquisition of seismic data furthermore the estimated temperatures during different times of data acquisition correlate well with the expected diurnal variation in temperature

ultrahigh resolution seismic reflection imaging of the alpine fault new zealand 1 high resolution seismic reflection surveys across active fault zones are capable of supplying key structural information required for assessments of seismic hazard and risk we have recorded a 360 m long ultrahigh resolution seismic reflection profile across the alpine fault in new zealand the alpine fault a continental transform that juxtaposes major tectonic plates is capable of generating large m 7 8 damaging earthquakes our seismic profile across a northern section of the fault targets fault zone structures in holocene to late pleistocene sediments and underlying triassic and paleozoic basement units from 3 5 to 150 m depth since ultrashallow seismic data are strongly influenced by near surface heterogeneity and source generated noise an innovative processing sequence and nonstandard processing parameters are required to produce detailed information on the complex alluvial glaciofluvial and glaciolacustrine sediments and shallow to steep dipping fault related features we present high quality images of structures and deformation within the fault zone that extend and complement interpretations based on shallow paleoseismic and ground penetrating radar studies our images demonstrate that the alpine fault dips 75 80 to the southeast through the quaternary sediments and there is evidence that it continues to dip steeply between the shallow basement units we interpret characteristic curved basement surfaces on either side of the alpine fault and deformation in the footwall as consequences of normal drag generated by the reverse slip components of displacement on the fault the fault dip and apparent 35 m vertical offset of the late pleistocene erosional basement surface across the alpine fault yield a provisional dip slip rate of 2 0 0 6 mm yr the more significant dextral slip rate cannot be determined from our seismic profile

detailed images of the shallow alpine fault zone new zealand determined from narrow azimuth 3d seismic reflection data previous high resolution seismic reflection investigations of active faults have been based on 2d profiles unfortunately 2d data may be contaminated by out of the plane reflections and diffractions that may be difficult to identify and eliminate although full 3d seismic reflection methods allow out of the plane events to be recognized and provide superior resolution to 2d methods they are only rarely applied in environmental and engineering studies because of high costs a narrow azimuth 3d acquisition and processing strategy is introduced to produce a high resolution seismic reflection volume centered on the alpine fault zone new zealand the shallow 3d images reveal late quaternary deformation structures associated with this major transpressional plate boundary fault the relatively inexpensive narrow azimuth 3d acquisition pattern consisting of inline source and receiver lines was easily implemented in the field to provide 2 by 4 m cmp coverage over an approximately 500 by 200 m area the narrow

estimation of azimuthal anisotropy from vsp data using multicomponent s wave velocity analysis observation of azimuthal shear wave anisotropy can be useful for characterization of fractures or stress fields shear wave anisotropy is often estimated by measuring splitting of individual shear wave events in vertical seismic profile vsp data however this method may become unreliable for zero offset marine vsp where the seismogram often contains no strong individual shear events such as direct downgoing shear wave but often contains many low amplitude ps mode converted waves we have developed a new approach for estimation of the fast and slow shear wave velocities and orientation of polarization planes based on the multicomponent linear traveltime moveout velocity analysis this technique is applicable to zerooffset vsp data and should take advantage of the presence of a large number of shear wave events with the same apparent velocity which for a horizontally layered medium should be close to the interval velocity the approach assumes that the vsp data are acquired in a vertical well drilled in an orthorhombic medium with a horizontal symmetry plane including horizontal transverse isotropy the main idea is to estimate the dominant apparent velocity for a given polarization direction by measuring the coherency of the seismic signal of a large number of events as a function of the apparent velocity the algorithm was tested on marine three component 3c vsp acquired in the north west shelf of australia and on land 3c vsp acquired with different sources in the same borehole located in otway basin victoria these tests show good agreement between anisotropy parameters magnitude and orientation derived from the vsp and cross dipole sonic log data

lunar ferroan anorthosites mineralogy compositional variations and petrogenesis detailed petrologic study of a suite of lunar ferroan anorthosites indicates that their mineral compositional variations are generally consistent with derivation of these anorthosites from a common parent magma there are continuous compositional variations in major elements and smooth trends in minor elements mg fe in plagioclase al ti cr in pyroxene relict textures zoning and possible primary trends of mineral compositional variations are preserved in many of the anorthosites the presence of heterogeneous bimodal and or trimodal pyroxene compositions suggests that some of the anorthosites are polymict rocks however they are composed entirely of ferroan anorthosite suite lithologies some aspects of the mineral composition data suggest that complex processes operated during formation of the ferroan anorthosites the lack of a well defined positive or negative trend of pyroxene mg mg fe versus plagioclase anorthite content the homogenization of mineral compositions in some anorthosites and the varied and apparently enriched mn contents of pyroxenes in some anorthosites suggest that original igneous compositional characteristics have been altered during and or after crystallization processes operative during anorthosite formation may have included some mixing of different melts trapping of variable amounts of intercumulus liquid postcrystallization redistribution of elements or perturbations both during adcumulus growth and subsequent to crystallization by impact events feo and mgo contents of the highly calcic plagioclase typical of these anorthosites suggest that the plagioclase melt distribution coefficients for these elements need to be reassessed

uncommon behavior of plagioclase and the ancient lunar crust calcic plagioclase the dominant mineral of the anorthositic lunar crust fails to show the na enrichment during cooling that is typical of magmatic plagioclase we show that this enigmatic behavior may arise during fractionation of highly calcic plagioclase at depths greater than 70 km in the lunar magma ocean because of the development of a negative azeotropic configuration at high anorthite contents that impedes and may even reverse the standard plagioclase albite enrichment with dropping temperature this result supports a high pressure origin of this plagioclase consistent with the lunar magma ocean model it also provides a new mechanism for forming lunar lithologies with sodic plagioclase from a highly na depleted moon through gravitational settling of spinel and refines the compositional characteristics of the late stage residual liquids of the lunar magma ocean

the effect of melt distribution on the rheology of plagioclase rocks abstract synthetic plagioclase aggregates were fabricated by hot isostatic pressing glass powder with an60ab40 composition at a confining pressure of 300 mpa and a temperature of 1223 k the residual glass content 15 vol was reduced to 1 3 vol by annealing the specimens at temperatures between 1423 and 1523 k at 0 1 mpa high resolution electron microscopy showed that the residual glass was confined to grain triple junctions when these samples were annealed at 0 1 mpa and above the solidus 1620 k they also contained silica rich amorphous phases at grain boundaries other samples were hot pressed at 1423 k they often have grain boundaries containing thin amorphous films 5 50 nm wide the chemical composition of the films differs from pure labradorite with up to 80 wt sio2 the volume fraction of si rich glass increases up to 2 vol for samples that contain 1 wt water uniaxial creep experiments were performed at temperatures of 1373 1638 k and stresses between 2 and 50 mpa the plagioclase aggregates deformed by grain size sensitive creep with a stress exponent n 1 the activation energy for grain boundary diffusion controlled creep of the partially molten aggregates was 400 20 kj mol 1 it remained unchanged with varying glass content and glass topology the strength of samples containing glass along grain boundaries is 4 10 times less than without amorphous grain boundary films the transition between diffusion and dislocation creep is shifted towards higher stresses for samples that contain glass films at grain boundaries

cogenetic rock fragments from a lunar soil evidence of a ferroan noritic anorthosite pluton on the moon abstract the impact that produced north ray crater apollo 16 landing site exhumed rocks that include relatively mafic members of the lunar ferroan anorthositic suite bulk and mineral compositions indicate that a majority of 2 4 mm lithic fragments from sample 67513 including impact breccias and monomict igneous rocks are related to a common noritic anorthosite precursor compositions and geochemical trends of these lithic fragments and of related samples collected along the rim of north ray crater suggest that these rocks derived from a single igneous body this body developed as an orthocumulate from a mixture of cumulus plagioclase and mafic intercumulus melt after the plagioclase had separated from any cogenetic mafic minerals and had become concentrated into a crystal mush 70 wt plagioclase 30 wt intercumulus melt we present a model for the crystallization of the igneous system wherein system is defined as cumulus plagioclase and intercumulus melt the initial accumulation of plagioclase is analogous to the formation of thick anorthosites of the terrestrial stillwater complex however a second stage of formation is indicated involving migration of the cumulus plagioclase intercumulus melt system to a higher crustal level analogous to the emplacement of terrestrial massif anorthosites compositional variations of the lithic fragments from sample 67513 are consistent with dominantly equilibrium crystallization of intercumulus melt the highly calcic nature of orthocumulus pyroxene and plagioclase suggests some reaction between the intercumulus melt and cumulus plagioclase perhaps facilitated by some recrystallization of cumulus plagioclase bulk compositions and mineral assemblages of individual rock fragments also require that most of the mafic minerals formed in close contact with cumulus plagioclase not as separate layers the distribution of compositions and by inference modes has a narrow peak at anorthosite and a broader larger peak at noritic anorthosite characteristics of the samples and their geochemical trends imply an origin in a system that was large relative to the unknown size of the impact that produced the brecccas of ferroan noritic anorthosite composition that were excavated later by the formation of north ray crater and they appear to be consistent with an origin of the suite within a perched plagioclase cumulate if the moon s crust formed by accumulation of plagioclase in a magma ocean ferroan noritic anorthosite formed as an orthocumulate is an alternative to extensive adcumulus formation of ferroan anorthosite 90 vol plagioclase this provides a relatively mafic ferroan anorthositic component 15 vol mafics which is required by mass balance models of compositions of polymict lunar crustal materials the inferred bulk composition of the system of cumulus plagioclase and intercumulus melt is similar to that of ferroan regolith breccia macalpine hills 88104 5 a lunar highland meteorite and may represent a common and widespread component of the moon s early highland crust

localized pluton deformation and linked focused flow of low volume fraction residual melt in deforming plagioclase cumulates shear hosted sub cm to 50 m wide fe ti zr ree ftzr rich melt bands occur exclusively at folded margins of the bolangir anorthosite pluton eastern india transverse to margin parallel foliation in anorthosite the n to nnw trending ftzr melt bands are oriented at a low angle 90 fractionation of anorthosites from crustally contaminated high al gabbro hag parent melt at the high degree of crystal fractionation crystal content higher than the particle locking threshold the ftzr melts during last stages of crystallization were locked within the plagioclase dominated cumulus pile the occurrence of ftzr melt bands exclusively at folded as opposed to straight segments of pluton margin is attributed to melt enhanced strain localization in the pluton induced by the ftzr melts locked within anorthosite further melt induced straining led to focusing of the ftzr melts along dilatant shear zones formed synchronously with the east west shortening deformation the variable widths of the melt bands correspond to the varying sizes of actively deforming magmatic plagioclase in anorthosite the extraction and transport of locked in low volume fraction melt documented here suggest long duration far field stresses may segregate and transport large volumes of low volume fraction melts in planetary interior over considerable distance

on equations for the speed of sound in seawater long range acoustic transmissions made in conjunction with extensive environmental measurements and accurate mooring position determinations have been used to test the accuracy of equations used to calculate sound speed from pressure temperature and salinity the sound speed field computed using the del grosso equation v a del grosso j acoust soc am 56 1084 1091 1974 give predictions of acoustic arrival patterns which agree significantly better with the long range measurements than those computed using the chen and millero equation c chen and f j millero j acoust soc am 62 1129 1135 1977 the predicted ray travel times and travel time error have been calculated using objectively mapped sound speed fields computed from ctd and xbt data using the measured and predicted ray travel times a negligible correction to del grosso s equation of 0 05 0 05 m s at 4000 m depth is calculated small errors of about 50 m in the gps determination of mooring positions lends a depth independent error of 0 1 m s to the sound speed equation correction work supported by nsf and onr

coupled thermal orbital evolution of the early moon abstract coupled thermal orbital histories of early lunar evolution are considered in a simple model we consider a plagioclase lid overlying a magma ocean overlying a solid mantle tidal dissipation occurs in the plagioclase lid and heat transport is by conduction and melt migration we find that large orbital eccentricities can be obtained in this model we discuss possible consequences of this phase of large eccentricities for the shape of the moon and geochronology of lunar samples we find that the orbit can pass through the shape solution of garrick bethell et al garrick bethell i wisdom j zuber m 2006 science 313 652 but we argue that the shape cannot be maintained against elastic deformation as the orbit continues to evolve

an analytical solution to assess the sh seismoelectric response of the vadose zone fil monachesi leonardo bruno universidad nacional de rio negro sede alto valle instituto de investigaciones en paleobiologia y geologia argentina consejo nacional de investigaciones cientificas y tecnicas argentina

experimental insights on the geometry and kinematics of fold and thrust belts above weak viscous evaporitic decollement abstract this paper discusses the differences in mechanical properties and kinematics between fold and thrust belts detaching on evaporitic decollements and those detaching on stronger detachments physical experiments are described that model shortening of a thick brittle cover overlying a weak viscous decollement to gain a better understanding of these differences we tested the influence of 1 the decollement layer thickness and 2 the presence of a deformable backstop on the hinterland side and of a decollement pinch out on the foreland side because of the very low shear strength of the viscous decollement folds and thrusts did not propagate according to a piggy back sequence but by centripetal back and forth propagation additional shortening was accommodated by growth of all existing structures fold symmetry and thrust vergence varied between experiments models confined between two rigid vertical endwalls always deformed by symmetric folding and thrusting in models having a deformable backstop and a foreland decollement pinch out forethrusting initially dominated folds were asymmetric and fault blocks rotated in models having a thick decollement layer folds kept growing asymmetrically diapirism also depended on the initial decollement geometry diapirs formed only in models having a deformable backstop and were restricted to the hanging wall of a fault related fold finally the implications of such kinematics on the thermal history are discussed as well as the likelihood of hydrocarbon maturation and preservation

near surface mapping using sh wave and p wave seismic land streamer data acquisition in illinois u s human activities have considerable impact on the upper 300 m of sediments of the earth conflicting activities in highly populated areas involving groundwater exploitation aggregate extraction and hazardous chemical related production and storage induce stress on the environment nearly half the population living around the great lakes depends on shallow groundwater aquifers a coalition of four great lakes states illinois indiana michigan and ohio in conjunction with the u s geological survey has initiated a program to map this sensitive upper 300 m layer as part of this effort the illinois state geological survey isgs has undertaken the task of preparing 3d quadrangle maps of the upper 100 m of the entire state at a scale of 1 24 000 although large scale maps indicating potential aquifer contamination already exist figure 1 very little is known about the groundwater pathways through the upper sedimentary column which mainly consists of deposits from the quaternary continental glacier

time lapse difference static correction using prestack crosscorrelations 4d seismic image enhancement case from ketzin abstracta method for static correction of time lapse differences in reflection arrival times of time lapse prestack seismic data is presented these arrival time differences are typically caused by changes in the near surface velocities between the acquisitions and had a detrimental impact on time lapse seismic imaging trace to trace time shifts of the data sets from different vintages are determined by crosscorrelations the time shifts are decomposed in a surface consistent manner which yields static corrections that tie the repeat data to the baseline data hence this approach implies that new refraction static corrections for the repeat data sets are unnecessary the approach is demonstrated on a 4d seismic data set from the ketzin co2 pilot storage site germany and is compared with the result of an initial processing that was based on separate refraction static corrections it is shown that the time lapse difference static correction approach reduces 4d noise more effectively than separate refra

shear wave reflection seismics as a valuable tool for near surface urban applications subsurface investigations in urban areas have to take sealed surfaces and densely built and populated areas into account the shear wave reflection seismic system developed at the leibniz institute for applied geophysics liag provides a solution for this acquisition technology problem using horizontally polarized shear waves sh waves and noninvasive source and receiver designs

azimuthal anisotropy of the megaregolith at the apollo 14 landing site the characterization of the megaregolith on the moon has been investigated in various ways including analysis of lunar meteorites remote sensing of mineralogy and gravity and deriving a seismic velocity profile in this study we propose a method for analyzing azimuthal anisotropy of the megaregolith we call this method deep moonquake seismic interferometry applied to s wave coda dmsi s dmsi s can turn the records of deep moonquakes into recordings from virtual active sources the retrieved virtual sources coincide with the station positions and thus we obtain virtual zero offset pulse echo measurements dmsi s is applied to seven clusters of deep moonquakes recorded at the apollo 14 landing site resulting in virtual zero offset measurements at the apollo station 14 we use the s wave recordings retrieved from dmsi s to analyze azimuthal anisotropy we find weak anisotropy at the layer where the megaregolith is assumed to be present we interpret our result to show that the megaregolith at this site is characterized by a layer or layers of impact material following the imbrium impact with internal alignment of the crushed material

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

near surface fault detection using high resolution shear wave reflection seismics at the co2crc otway project site australia high resolution near surface shear wave reflection seismic measurements were carried out in november 2013 at the co2crc otway project site victoria australia with the aim to determine and if so where deeper faults reach the near subsurface from a previous p wave 3 d reflection seismic data set that was concentrated on a reservoir at 2 km depth we can only interpret faults up to 400 m below sea level for the future monitoring in the overburden of the co2 reservoir it is important to know whether and how the faults continue in the subsurface we prove that two regional fault zones do in fact reach the surface instead of dying out at depth individual first break signatures in the shot gathers along the profiles support this interpretation however this finding does not imply perforce communication between the reservoir and the surface in the framework of co2 injection the shear wave seismic sections image with high resolution better than 3 m vertically and complementary to existing p wave volumes different tectonic structures similar structures also outcrop on the southern coast of the otway basin both the seismic and the outcrops evidence the complex youngest structural history of the area

adaptive picking of refracted first arrivals1 static correction computations require knowledge of the refracted traveltimes zero phase wavelet sources cannot be picked reliably when incoherent picking techniques are used assuming a complex convolutional model for vibroseis a coherent picking technique based on the matched filter is described in order to match the filter to the first arrival wavelet an adaptive algorithm is used this allows the filter to change both with shot and offset so that all the properties of matched filtering such as improvement of s n and resolution can be exploited incoherent picking is used before coherent picking to improve the convergence of adaptive picking

mineralogy of the lunar crust results from clementine received 1997 december 5 accepted in revised form 1998 september 15 abstract the central peaks of 109 impact craters across the moon are examined with clementine ultraviolet visible uvvis camera multispectral data the craters range in diameter from 40 to 180 km and are believed to have exhumed material from 5 30 km beneath the surface to form the peaks including both upper and lower crustal rocks depending on whether craters have impacted into highlands or basins representative five color spectra from spectrally and spatially distinct areas within the peaks are classified using spectral parameters including key ratio which is related to mafic mineral abundance and spectral curvature linked to absorption band shape which distinguishes between low and high ca pyroxene and olivine the spectral parameters are correlated to mineralogical abundances related in turn to highland plutonic rock compositions the derived rock compositions for the various central peaks are presented in a global map from these results it is evident that the lunar crust is compositionally diverse both globally and at local 100 m scales found within individual sets of central peaks although the central peaks compositions imply a crust that is generally consistent with previous models of crustal structure they also indicate a more anorthositic crust than generally assumed with a bulk plagioclase content of 8 1 evolving from pure anorthosite near the surface towards more mafic low ca pyroxene rich compositions with depth comparable to anorthositic norite evidence for mafic plutons occurs in both highlands and basins and represent all mafic highland rock types however the lower crust is more compositionally diverse than the highlands with both a greater range of rock types and more diversity within individual sets of central peaks

repeatability analysis of land time lapse seismic data co2crc otway pilot project case study time lapse seismics is the methodology of choice for remotely monitoring changes in oil gas reservoir depletion reservoir stimulation or co 2 sequestration due to good sensitivity and resolving power at depths up to several kilometres this method is now routinely applied offshore however the use of time lapse methodology onshore is relatively rare the main reason for this is the relatively high cost of commercial seismic acquisition on land a widespread belief of a relatively poor repeatability of land seismic data prevents rapid growth in the number of land time lapse surveys considering that co 2 sequestration on land is becoming a necessity there is a great need to evaluate the feasibility of time lapse seismics for monitoring therefore an understanding of the factors influencing repeatability of land seismics and evaluating limitations of the method is crucially important for its application in many co 2 sequestration projects we analyse several repeated 2d and 3d surveys acquired within the otway co2 sequestration pilot project operated by the cooperative research centre for greenhouse technologies co2crc in australia in order to determine the principal limitations of land time lapse seismic repeatability and investigate the influence of the main factors affecting it our findings are that the intrinsic signal to noise ratio s n signal to coherent and background noise levels and the normalized root meansquare nrms difference are controlled by the source strength and source type however the post stack s n ratio and corresponding nrms residuals are controlled mainly by the data fold for very high fold data the source strength and source type are less critical

surface and borehole seismic imaging of soft rock karst eolianites at coastal engineering construction sites case studies from australia eolianite dune calcarenite or kurkar occur in many parts of the world as a coastal limestone whose formation is controlled by quaternary climate change eolianite commonly has relatively low strength high variability and contains voids associated mainly with syngenetic karst the presence of eolianite increases risks and costs to civil engineering construction seismic imaging of voids and weaker zones within soft rock eolianites with p waves is challenging as the material properties contrasts are often relatively small and highly variable

first arrival picking on common offset trace collections for automatic estimation of static corrections the increase in the number of geophone groups in production records during recent years and the requirement for accurate basic static corrections for high resolution records have made it necessary to develop sufficiently accurate automatic techniques for the determination of static corrections a fully automatic method is presented which makes use of the delay time method in order to compute static corrections at each shot position delay times weathering and subweathering velocities are determined from automatic picks of the first arrivals on common offset trace collections it is assumed that the weathering is a single layer and that the dip of the subweathering layer under the geophone groups is small the picking routine is fully automatic and successful in most cases provided the signal to noise ratio is sufficiently high the subsequent filtering of erroneous values for picked times is performed by means of statistical techniques using curves of picked times on common offset trace collections if the distance between receivers and shot points on the profile is sufficiently short one can expect only little change in the picked times of two contiguous traces the method is well adapted to end on spreads with a great number of traces where distances between geophone groups are short examples are presented showing the possibilities of the method for the determination of long wavelength as well as short wavelength components of static corrections

heat pipe planets abstract observations of the surfaces of all terrestrial bodies other than earth reveal remarkable but unexplained similarities endogenic resurfacing is dominated by plains forming volcanism with few identifiable centers magma compositions are highly magnesian mafic to ultra mafic tectonic structures are dominantly contractional and ancient topographic and gravity anomalies are preserved to the present here we show that cooling via volcanic heat pipes may explain these observations and provide a universal model of the way terrestrial bodies transition from a magma ocean state into subsequent single plate stagnant lid convection or plate tectonic phases in the heat pipe cooling mode magma moves from a high melt fraction asthenosphere through the lithosphere to erupt and cool at the surface via narrow channels despite high surface heat flow the rapid volcanic resurfacing produces a thick cold and strong lithosphere which undergoes contractional strain forced by downward advection of the surface toward smaller radii we hypothesize that heat pipe cooling is the last significant endogenic resurfacing process experienced by most terrestrial bodies in the solar system because subsequent stagnant lid convection produces only weak tectonic deformation terrestrial exoplanets appreciably larger than earth may remain in heat pipe mode for much of the lifespan of a sun like star

a test of basin scale acoustic thermometry using a large aperture vertical array at 3250 km range in the eastern north pacific ocean broadband acoustic signals were transmitted during november 1994 from a 75 hz source suspended near the depth of the sound channel axis to a 700 m long vertical receiving array approximately 3250 km distant in the eastern north pacific ocean the early part of the arrival pattern consists of raylike wave fronts that are resolvable identifiable and stable the later part of the arrival pattern does not contain identifiable raylike arrivals due to scattering from internal wave induced sound speed fluctuations the observed ray travel times differ from ray predictions based on the sound speed field constructed using nearly concurrent temperature and salinity measurements by more than a priori variability estimates suggesting that the equation used to compute sound speed requires refinement the range averaged ocean sound speed can be determined with an uncertainty of about 0 05 m s from the observed ray travel times together with the time at which the near axial acoustic reception ends used as a surroga

orogenic wedge growth during collision constraints on mechanics of a fossil wedge from its kinematic record rhenohercynian ftb central europe abstract the kinematic evolution of the rhenohercynian fold and thrust belt of the central european variscides can be reconstructed from incremental strain and palaeostress data synkinematic metamorphism geochronology synorogenic sediments and the geometry of shortening this data set allows to infer the mechanical development with respect to the mohr coloumb theory of critically tapered orogenic wedges growth of the rhenohercynian orogenic wedge was kinematically partitioned into a broad orogen normal moving and a narrow obliquely moving domain the ratio of the final widths of these domains varies from 1 6 to 2 3 this low ratio indicates strong basal coupling growth averages are 14 km ma of shortening and a strain rate of 6 10 16 s 1 the mode of mass transfer from lower to upper plate which controlled the accretion geometry and the particle paths evolved in the long term from dominantly basal to frontal accretion this evolution was accompanied by a decrease in taper from precollisional 18 28 to final 5 8 4 6 accretionary subsystems assemble the wedge each is characterised by a sequence of basal to frontal accretion both rooting in a common detachment the development of the subsystems is supported by the observation of stepwise migration of a foreland bulge ponding flysch subbasins these features imply shorter termed ca 2 ma cyclic mass transfer above a high friction detachment with episodes of basal accretion followed by episodes of a quickly forward propagating thrust front transfer of the basal detachment from ductile mid crustal to brittle conditions via a crustal ramp and particle flow across the ramp provoked large scale adjustment of wedge geometry internal wedge thickening is spatially and chronologically related to the formation of the ramp and was supported by surficial erosion of ca 3 kbar for keeping a critical taper three growth stages of the wedge can be reconstructed the high taper of the precollisional stage plots in the tectonically erosive field in a taper stability diagram then taper decreases to 10 after emplacement of a flysch nappe stack during the final stage of contraction an eastern and a western branch develop with geometries fluctuating around a critically stable state the two branches link with differences in large scale wedge architecture bulk contraction and detachment geometry the latter being controlled by the former basin geometry

fault system and thermal regime in the vicinity of site nghp 01 10 krishna godavari basin bay of bengal abstract drilling coring activities onboard joides resolution for hydrate resource estimation have confirmed gas hydrate in the continental slope of krishna godavari kg basin bay of bengal and the expedition recovered fracture filled gas hydrate at the site nghp 01 10 in this paper we analyze high resolution multi channel seismic mcs high resolution sparker hrs bathymetry and sub bottom profiler data in the vicinity of site nghp 01 10 to understand the fault system and thermal regime we interpreted the large scale fault system 5 km predominantly oriented in nnw sse direction near nghp 01 10 site which plays an important role in gas hydrate formation and its distribution the increase in interval velocity from the baseline velocity of 1600 m s to 1750 1800 m s within the gas hydrate stability zone ghsz is considered as a proxy for the gas hydrate occurrence whereas the drop in interval velocity to 1400 m s suggest the presence of free gas below the ghsz the analysis of interval velocity suggests that the high concentration of gas hydrate occurs close to the large scale fault system we conclude that the gas hydrate concentration near site nghp 01 10 and likely in the entire kg basin is controlled primarily by the faults and therefore has high spatial variability we also estimated the heat flow and geothermal gradient gtg in the vicinity of nghp 01 10 site using depth and temperature of the seafloor and the bsr we observed an abnormal gtg increase from 38 c km to 45 c km at the top of the mound which remarkably agrees with the measured temperature gradient at the mound nghp 01 10 and away from the mound nghp 01 03 we analyze various geological scenarios such as topography salinity thermal non equilibrium of bsr and fluid gas advection along the fault system to explain the observed increase in gtg the geophysical data along with the coring results suggest that the fluid advection along the fault system is the primary mechanism that explains the increase in gtg the approximate advective fluid flux estimated based on the thermal measurement is of the order of few tenths of mm yr 0 37 0 6 mm yr

comparing state of the art near surface models of a seismic test line from saudi arabia we present a seismic test line provided by saudi aramco for various research teams to highlight a few major challenges in land data processing due to near surface anomalies we discuss state of the art methods used to compensate for shallow distortions including single layer multilayer plus minus refraction and tomostatics methods they are a starting point for the new technologies presented in other papers all dealing with the same challenging data described here the difficulties on the test line are mostly due to the assumption of vertical raypaths inherent in classical applications of near surface correction statics even the most detailed velocity depth model presents difficulties due to the complex raypath there is a need for methods which are based on more complex models and theories

thermohaline fine structure in an oceanographic front from seismic reflection profiling we present acoustic images of oceanic thermohaline structure created from marine seismic reflection profiles across the major oceanographic front between the labrador current and the north atlantic current the images show that distinct water masses can be mapped and their internal structure imaged using low frequency acoustic reflections from sound speed contrasts at interfaces across which temperature changes the warm cold front is characterized by east dipping reflections generated by thermohaline intrusions in the uppermost 1000 meters of the ocean our results imply that marine seismic reflection techniques can provide excellent spatial resolution of important oceanic phenomena including thermohaline intrusions internal waves and eddies

structure and kinematics of an outcrop scale fold cored triangle zone triangle zones are widespread structural elements that link fold and thrust belts with their foreland basins we present a structural analysis of an outcrop scale 6 m 20 ft wide triangle zone that is exposed in the siliciclastic carboniferous strata of the harz mountains in northern germany the geometry of the triangle zone is critically compared with larger outcrop and seismic scale structures the external form of the triangle zone is the same as that proposed for larger examples with two bounding detachments that dip in opposing directions however the interior of the triangle zone is characterized by tight to isoclinal folds we demonstrate how the triangle zone probably evolved from a fault bend fold which accreted further folds behind it this is an alternative fold based interpretation for a structure that is commonly modeled as a duplex stack we present the resulting consequences for seismic interpretation and hydrocarbon reservoir evaluation

adcumulus growth of anorthosite at the base of the lunar crust unzoned plagioclase crystals imply isothermal adcumulus solidification and cannot result from reactive equilibrium crystallization in dry magma extraction of latent heat upward through lunar crust results only in chilled or cotectic mesocumulate rocks not anorthosite or adcumulates adcumulus growth of anorthosite requires exchange of refractory for incompatible components between the site of crystal growth and nearby fresh magma and the extraction of calories from growing crystals to the flowing supercooled magma supercooling can be acquired at remote sites like upwellings and then be carried by convective flow beneath crust which is accreting plagioclase by flotation or in situ nucleation and growth if transport distances are larger than the scale of rockbergs cotectic norites and troctolites may result impact induced upwellings tend to promote growth of buoyant rather than mafic crust hence impacts are not solely destructive

structural evaluation of column height controls at a toe thrust discovery deep water niger delta industry discoveries to date in the deep water toe thrust play have limited column heights and lack any unequivocal thrust fault dependent hydrocarbon columns the causes of the limited success are controversial the main issue being whether the encountered columns are caused by leaking thrust faults or other causes the controversy is in large part caused by the presence of no seismic image zones that even on three dimensional 3 d prestack migrated data obscure the possible thrust cutoffs we use dipmeter seismic stratigraphic and fluid pressure data to construct an integrated geometrically and kinematically balanced cross section through a recent toe thrust discovery in which a prominent no seismic image zone on the southwest flank of the alpha structure appeared to be a thrust fault zone holding about 100 m 328 ft of thrust fault dependent oil column to constrain the structure within the unimaged forelimb dip panels and fold axial surfaces were constructed from dipmeter data recorded in both a vertical hole and a sidetrack well through the no seismic image zone stratigraphic tops from both wells were projected through the no seismic image zone using the dip panels and axial surfaces maintaining the observed stratigraphic thicknesses these data and analyses tightly constrain potential fault locations and offsets within the no data zone the resulting structural model shows that the no seismic image zone in the forelimb is not a thrust but instead an overturned limb without any fault offset of the pay section the results show that the trapped hydrocarbons are confined completely within the four way dip closure and that the trap s potential is not limited by the thrust faults seal capacities in addition top seal analyses show that top seal integrity is not a limiting factor for hydrocarbon column heights at the present time and has not been a limiting factor throughout the geological history of the structure taken together these observations indicate that the column heights are most likely controlled by access to charge instead of trap integrity consistent with an observed lack of thermogenic hydrocarbons in nearby four way dip closures these conclusions imply that where sufficient access to thermogenic charge is present there may be additional thrust fault dependent hydrocarbon columns

geomorphological evidence of neotectonic deformation in the carnarvon basin western australia abstract this study examines channel scale morphodynamics of ephemeral streams in the onshore carnarvon basin in arid west central western australia the rivers in this region have low gradients the landscape has low relief and the rates of climatically and tectonically driven geomorphic processes also are low as a result the rivers in the carnarvon alluvial plain are highly sensitive to minor perturbations in base level channel slope and fluvial energy we use channel planform adjustments stream gradient changes and floodplain profiles across multiple ephemeral streams within a variety of catchments and flow regimes to determine if tectonically driven land level changes are affecting channel form and fluvial processes growth of individual fold segments is shown to have altered stream and floodplain gradients and triggered repeated avulsions at structurally controlled nodes aligned perturbations in channel form across multiple channel fold intersections provide systematic geomorphic evidence for the location and orientation of neotectonic structures in the region these features occur as a belt of low relief anticlines in the carnarvon alluvial plain

mechanics of triangle zones and passive roof duplexes implications of finite element models abstract finite element models of passive roof duplexes simulate the evolution and distribution of fault slip and deformation as functions of boundary conditions friction on the roof fault cover strength and amount of overburden a foreland buttress is essential for backthrust displacement in the models this foreland buttress is analogous to a pin line between the cover and footwall forelandward of the triangle zone in a balanced cross section and could be caused by a stratigraphic pinchout of the upper detachment or a strong cover in the foreland with boundary conditions that prevent the cover from slipping toward the hinterland relative to the wedge incipient forethrust and backthrust ramps zones of high equivalent plastic strain cut through the cover in the models there is more backthrust displacement with a lower friction coefficient on the upper detachment and with a stronger cover because of pressure dependence both fault strength and material strength increase with increasing overburden therefore the effect of overburden on backthrust displacement is determined by the nature of the pressure dependencies for fault friction and material strength in models with multiple imbricate faults the distribution of equivalent plastic strain adjacent to each fault is similar to that in single fault models with differences resulting from bending strains in the wedge and cover the strain distribution in the cover of the models is similar to that above natural passive roof duplexes characterized by layer parallel shortening above the tip of each horse in the duplex

triangle zones geometry kinematics mechanics and the need for appreciation of uncertainties abstract triangle zones are important structures found in foreland fold and thrust belts all over the world and are commonly associated with tectonic wedging however tectonic wedging and consequently the formation of passive hinterland verging roof thrusts requires particular mechanic conditions such as pre fractured rocks syntectonic sedimentation or a specific stratigraphic layering with variable mechanically weak and rigid formations in this contribution models of triangle zones and hypotheses regarding their formation are reviewed our results show that the term triangle zone is often used in a contradictory sense and interpretations are affected by large uncertainties passive roof thrusts are not necessarily required in all cases and suggested models of triangle zones even if they are geometrically and kinematically viable are hampered by their mechanical implications with respect to a large number of published triangle zones and associated kinematic as well as mechanic models we present a new definition and classification scheme which is discussed and applied to natural examples worldwide we show that natural examples of triangle zones can be separated into two types 1 detachment dominated and 2 ramp dominated triangle zones both types imply particular mechanic conditions of involved detachments and regional dynamics regarding the large uncertainties associated with triangle zone interpretation we suggest to only use the term triangle zone in a very stringent manner and only if irrefutable evidences for stratigraphic repetitions within a duplex are given the results should then be validated with additional kinematic and mechanic considerations geometric and kinematic uncertainties as well as implications of the proposed model explaining observed triangular structures should be reflected in the nomenclature used

thermal and magmatic evolution of the moon as with all science our continually developing concepts of lunar evolution are firmly tied to both new types of observations and the integration of these observations to the known pool of data this process invigorates the intellectual foundation on which old models are tested and new concepts are built just as the application of new observational tools to lunar science in 1610 galileo s telescope and 1840 photography yielded breakthroughs concerning the true nature of the lunar surface the computational and technological advances highlighted by the apollo and post apollo missions and associated scientific investigations provided a new view of the thermal and magmatic evolution of the moon 1 1 pre apollo view of the thermal and magmatic evolution of the moon many of the early views of the moon manifested in mythology and art throughout the world were primarily tied to lunar and terrestrial cycles and the relationships between the sun and the moon prophetically myths involving the lunar deities mwuetsi from zimbabwe and coyolxauhqui from mexico told of rather violent or catastrophic events in which the moon was expunged from the earth numerous ancient scientific observations were made about the nature of the moon ranging from those uncovered in early neolithic sites that correctly identified mare crisium and mare humorum to the insights made by greek philosophers such as anaxagoras ca 500 428 b c and democritus ca 460 370 b c who attached terrestrial analogues to its character stone mountains with the advent of the telescope 1610 and photography 1840 as scientific tools for lunar exploration semiquantitative data could be collected that would provide an intellectual foundation for scientific interpretation initially modern terrestrial geological analogs were extended to the moon lunar highlands volcanic craters seas combined with the rigors of computational modeling these observational data were extended to predict the original thermal state of the moon and its thermal and magmatic history its proximity to the earth

a low viscosity lunar magma ocean forms a stratified anorthitic flotation crust with mafic poor and rich units much of the lunar crust is monomineralic comprising 98 plagioclase the prevailing model argues the crust accumulated as plagioclase floated to the surface of a solidifying lunar magma ocean lmo whether 98 pure anorthosites can form in a flotation scenario is debated an important determinant of the efficiency of plagioclase fractionation is the viscosity of the lmo liquid which was unconstrained here we present results from new experiments conducted on a late lmo relevant ferrobasaltic melt the liquid has an exceptionally low viscosity of 0 22 0 19 0 11 to 1 45 0 82 0 46 pa s at experimental conditions 1 300 1 600 c 0 1 4 4 gpa and can be modeled by an arrhenius relation extrapolating to lmo relevant temperatures our analysis suggests a low viscosity lmo would form a stratified flotation crust with the oldest units containing a mafic component and with very pure younger units old impure crust may have been buried by lower crustal diapirs of pure anorthosite in a serial magmatism scenario

two stage early cretaceous rifting of the otway basin margin of southeastern australia implications for rifting of the australian southern margin the otway basin of southeastern australia rifted from antarctica in two distinct stages in the early cretaceous the first stage began around 140 ma and ended between 110 and 120 ma and formed an onshore rift the rift faults typically detached within basement and were oriented between east west and east northeast on the crayfish platform these first stage rift structures are preserved the second stage of rifting at about 95 ma just prior to sea floor spreading had fault trends between east southeast and southeast it was less extensive in area and the zone of highest extension was localized near the junction with oceanic crust geohistory and tectonic analyses indicate that both stages of rifting affected the whole southern margin in the west however the first rift began at about 160 ma and first stage trends persisted during the second rift

the variscan belt in central europe main structures geodynamic implications open questions abstract the variscan belt of europe originated from the confrontation of northern europe and gondwana with intervening pre variscan blocks cadomian and older armorica tepla barrandean moravo silesian though a strike slip component cannot be excluded geological evidence suggests a subduction collision process newly discovered features include basaltic rocks with morb affinities high pressure metamorphic rocks trench deposits and large scale allochthonism which also affects the pre variscan basement and has often led to an inversion of the metamorphic isogrades large scale thrusting is evident at all crustal levels and is also observable by geophysical methods the structure of the variscan crust is best described as horizontal tectonic layering late ordovician through carboniferous convergence closed one rhenohercynian and one saxo thuringian basin to the north and at least one mediterranean basin to the south of the pre variscan blocks subduction occurred from the north as well as from the south down under the dorsal core region the exact timing and the driving mechanism of this bilateral activity remains a problem likewise uncertain are the exact limination of the pre variscan blocks and the existence and width of oceanic areas in the saxothuringian zone and in the south facing part of the moldanubian zone there is good evidence of early palaeozoic rifting and of late ordovician through carboniferous plate convergence palaeomagnetic and palaeoclimatic constraints however suggest only a limited extent of oceanic basins in these areas while they appear to allow a wider ocean at the rhenohercynian saxothuringian boundary which is relatively unobtrusive from the geological point of view research during the past decade has produced a wealth of information on the variscan fold belt in europe the resulting geodynamic models however are extremely diverging evidently it is not the time yet for definitive statements the present paper intends to review the state of knowledge to deduce such basic items of a geodynamic model as appear reasonably well documented and to point out the most urgent open questions stress will be laid on central europe which offers a complete cross section through the northern flank of the variscan belt and where we have carried out most of our studies during the last years

full waveform inversion of reflection seismic data for ocean temperature profiles 1 we show that ocean temperature profiles can be accurately recovered using only acoustic methods employed at the sea surface using a towed air gun array and a hydrophone streamer thermohaline boundaries are ensonified at a suite of frequencies and angles yielding travel time trajectories and reflectivities these data are inverted via full waveform inversion to estimate sound speed and subsequently a temperature profile the high lateral data density of the seismic technique offers the potential of acoustically derived temperature profiles to be used to constrain models of ocean mixing and internal waves results on realistic synthetic data show that sound speed can be recovered with arbitrary accuracy when using broadband data with known source function and recording geometry application to field seismic data corroborated by expendable bathythermograph shows that even with a seismic acquisition system not specifically calibrated for seismic oceanography temperature contrasts within the ocean can be recovered to within one degree celsius

the lunar magma ocean reconciling the solidification process with lunar petrology and geochronology abstract the moon is thought to have originated with a magma ocean that produced a plagioclase flotation crust as solidification proceeded ages of anorthositic crust range over at least 200 million years the model for solidification presented here integrates chemical and physical constraints of lunar magma ocean solidification to determine 1 the final thickness of flotation crust generated by a fractionally solidifying magma ocean 2 the timescale of crystallization before plagioclase is a stable phase 3 the timescale of solidification after the formation of the plagioclase flotation crust and 4 the post overturn lunar mantle composition and structure we find that magma oceans of as much as 1000 km depth are consistent with creating an anorthositic crust 40 to 50 km in thickness solidification of the magma ocean prior to formation of the flotation crust may occur on the order of 1000 years and complete solidification would require additional ten to tens of millions of years reconciling these short model timescales with radiometric dates of crustal samples requires either a very late forming moon combined with finding older crustal ages to be incorrect or calling on tidal heating of the crust by the early earth to prolong solidification gravitationally driven overturn of cumulates during tidal heating provides a mechanism for creating the compositions and ages of the lunar mg suite of crustal rocks further we find that upon crystallization the moon likely began with an azimuthally heterogeneous gravitationally stable mantle after magma ocean cumulate overturn this result may help explain the experimentally determined origin of picritic glasses at similar depths but from different source materials

fault related folding a review of kinematic models and their application abstract folding that is directly related to fault activity is an important deformation feature that occurs all over the world in mountain belts accretionary wedges fold and thrust belts and intra plate settings in either strike slip compressional or extensional regimes due to their widespread occurrence knowledge about the development of these structures is important to a broad spectrum of geoscience sub disciplines such as structural geology seismology geomorphology petroleum geology and quaternary geology fault related folding has been analyzed intensively over the last 140 years for the sake of this review we divide the folds according to the way the faults and the folds form that is into detachment fault bend and fault propagation folds all fault related folds are caused by changes in fault parameters the simplest method to produce folds is to transport material along faults that have stepped flat ramp flat geometries fault bend fold alternatively the slip can decrease along the length of the fault and depending on whether the fault remains within a detachment layer or steps up through mechanical stratigraphy either a detachment fold or a fault propagation fold is formed respectively detachment folding was first investigated in the early 20th century whereas the full significance of fault propagation folds was recognized quite late in the 1980s seminal work on fault related folding was carried out in the 1930s but quantitative kinematic models have only been available in the last 30 years these models are extremely valuable because they allow a comprehensive understanding of the evolution of fault related folds and lead to more accurate predictions of the sub surface structure from the mid 1990s onwards numerical simulations have been used to identify how fault parameters such as dip and fault bend angle propagation to slip ratio and shape of the trishear zone influence the geometry of the related folding this is directly applicable to the analysis of the shape of anticlines produced however this does not mean that fold geometry is uniquely related to fault geometry on the contrary different kinematic approaches can lead to a similar fold shape

chronology geochemistry and petrology of a ferroan noritic anorthosite clast from descartes breccia 67215 clues to the age origin structure and impact history of the lunar crust the petrology major and trace element geochemistry and nd ar sr isotopic compositions of a ferroan noritic anorthosite clast from lunar breccia 67215 have been studied in order to improve our understanding of the composition age structure and impact history of the lunar crust the clast designated 67215c has an unusually well preserved igneous texture mineral compositions are consistent with classification of 67215c as a member of the ferroan anorthositic suite of lunar highlands rocks but the texture and mineralogy show that it cooled more rapidly and at shallower depths than did more typical ferroan anorthosites fans incompatible trace element concentrations are enriched in 67215c relative to typical fans but diagnostic signatures such as ti sm sc sm plagiophile element ratios and the lack of zr hf and nb ta fractionation show that this cannot be due to the addition of kreep alternatively 67215c may contain a greater fraction of trapped liquid than is commonly present in lunar fans 147sm 143nd isotopic compositions of mineral separates from 67215c define an isochron age of 4 40 0 11 gyr with a near chondritic initial 143nd of 0 85 0 53 the 40ar 39ar composition of plagioclase from this clast records a post crystallization thermal event at 3 93 0 08 gyr with the greatest contribution to the uncertainty in this age deriving from a poorly constrained correction for lunar atmosphere 40ar rb sr isotopic compositions are disturbed probably by the same event recorded by the ar isotopic compositions trace element compositions of fans are consistent with crystallization from a moderately evolved magma ocean and do not support a highly depleted source composition such as that implied by the positive initial 143nd of the ferroan noritic anorthosite 62236 alternatively the nd isotopic systematics of lunar fans may have been subject to variable degrees of modification by impact metamorphism with the plagioclase fraction being more strongly affected than the mafic phases 147sm 143nd isotopic compositions of mafic fractions from the 4 ferroan noritic anorthosites for which isotopic data exist 60025 62236 67016c 67215c define an age of 4 46 0 04 gyr which may provide a robust estimate for the crystallization age of lunar ferroan anorthosites

massive layer of pure anorthosite on the moon 1 we present a new global survey of the purest anorthosite pan rock using the spectral profiler onboard kaguya we found that pan rocks are widely distributed over the moon including the feldspathic highland terrain and the south and north polar regions all pan sites are associated with huge impact structures with diameters larger than 100 km based on the global distributions of pan and olivine rich sites we propose the existence of a massive pan layer with a thickness of 50 km below an uppermost mafic rich mixed layer with a thickness of 10 km below the pan layer a lower crustal layer with olivine rich materials may be present on the nearside but not on the far side of the moon the existence of a pan layer with a thickness of 50 km suggests an al2o3 abundance of 33 to 34 wt in the lunar crust which is higher than previous estimates of 32 wt our data indicate the massive production event of pan during the early stage of the formation of the moon supporting the lunar magma ocean scenario

constraining helicopter electromagnetic models of the okavango delta with seismic refraction and seismic reflection data abstractelectrical resistivity models derived from exceptionally high quality helicopter transient electromagnetic data recorded across the okavango delta in botswana one of the world s great inland deltas or megafans include three principal layers 1 an upper heterogeneous layer of dry and water saturated sand 2 an intermediate electrically conductive layer that likely comprises saline water saturated sand and clay and 3 a lower fan shaped electrically resistive layer of freshwater saturated sand gravel and or crystalline basement if part of the lower layer comprises a freshwater aquifer it would be evidence for a recently proposed paleo okavango megafan and a major new source of freshwater in an attempt to constrain the interpretation of the lower layer we acquired two high resolution seismic refraction and re ection data sets at each of two investigation sites one near the center of the delta and one along its western edge the interface between unconsolidated sediments and basement near

a chemical model for generating the sources of mare basalts combined equilibrium and fractional crystallization of the lunar magmasphere abstract it is generally considered that mare basalts were generated by the melting of a cumulate mantle formed in an early moon wide magma ocean or magmasphere however the nature and chemistry of this cumulate mantle and the logistics of its origin have remained elusive extensive studies of terrestrial layered mafic intrusions over the past sixty years have emphasized the imperfection of fractional crystallization and attendant crystal crystal and crystal liquid separation in a convecting magma chamber crystal liquid and crystal crystal separations were similarly inefficient during evolution of the lunar magma ocean lmo allowing for the trapping of interstitial liquid and entrainment of a small proportion of less dense plagioclase into the denser mafic cumulate mush indeed petrography of lunar highlands samples demonstrates this for anorthosites with 1 10 olivine the residual liquid after 80 90 crystallization was very evolved in fact kreepy and even in small proportions 1 5 would have a noticeable effect on the trace element chemistry of melts generated from these cumulates this trapped residual liquid would elevate total ree abundances in the cumulate pile while synchronously deepening the already negative eu anomaly essentially this trapped liquid will make the cumulate more fertile for melting to generate both kreep basalt and mare basalt magmas plagioclase entrained in the mafic cumulate pile adds an essential al component to the high ti basalt source and will moderate the requisite negative eu anomaly in the cumulate early in the evolution of the lunar mantle when the lmo still was largely liquid it is likely that vigorous convection was an important factor in crystallization such convection would allow crystals to remain suspended and in equilibrium with the lmo liquid for relatively long periods of time this extended period of equilibrium crystallization would then have been followed by fractional crystallization once plagioclase became a liquidus phase and began to float to form the lunar highlands crust previous authors have proposed a three component model for the evolution of high ti mare basalt source regions this model includes kreep early olivine rich high mg cumulates and late ilmeniterich low mg cumulates in various proportions however we propose a model for high ti basalt parent magmas which is in accord with studies of terrestrial layered intrusions this model for the high ti source includes trapped instantaneous residual liquid tirl 1 3 and entrainment of a small 2 5 proportion of plagioclase into the late stage cumulate pile in order to account for both the observed al compositions and trace element characteristics of high ti mare basalts melting of this relatively shallow ilmenite and clinopyroxene bearing late stage cumulate can generate high ti mare basalt magmas furthermore we are in agreement with other workers that only through a process of nonmodal melting will the high ti values for the parent magmas be realized large scale convective overturn of the cumulate pile and mixing of kreep with early and late stage cumulates is not required however localized overturn of the upper tenth of the cumulate pile is likely and in fact required to achieve an appropriate major element balance for the high ti mare basalt source region

signature of fault zone deformation in near surface soil visible in shear wave seismic reflections small throw seismogenic fault segments hidden in the holocene sediments are crucial but difficult targets in seismic exploration we report here the detection of the deformation pattern and a concealed fault segment in the unconsolidated sediments at vila franca xira portugal through identification in shear wave reflection data of multiple signatures of ductile deformation associated with faulting we find step like changes in the stacking velocity along a shallow subsoil layer boundary indicating synsedimentary faulting we also recognize a consistent distortion in the moveout of the reflection events in the raw shear wave data synthetic modeling of seismic data helps in interpreting these observations and identifying backscattered energy from a steeply dipping shallow fault zone prior to this finding there was no evidence for holocene activity of this fault although the fault is considered to be the most probable source for the disastrous 1531 earthquake

passive roof duplex geometry in the frontal structures of the kirthar and sulaiman mountain belts pakistan abstract exploration for hydrocarbons over the past few years has greatly improved our understanding of the geometry of frontal mountain belt structures in this study we introduce and discuss the concept of the passive roof duplex using as the main example the kirthar and sulaiman ranges in the baluchistan province of pakistan structures similar to those described here have been recognized previously in other mountain belts and they appear to exist as a common feature in many more frontal regions of mountain belts our example of a passive roof duplex which we describe from pakistan is compared briefly with similar structures reported by others the passive roof duplex is here defined as a duplex whose roof thrust has backthrust sense passive roof thrust and whose roof sequence those rocks lying above the roof thrust remains relatively stationary during foreland directed piggy back style propagation of horses within the duplex