observations modeling and applications of ers envisat coherence over land surfaces european remote sensing satellite ers envisat coherence is a new repeat pass interferometric synthetic aperture radar product characterized by a very short repeat pass interval between acquisitions 28min in this paper we investigate the properties of two 28 mins coherence images acquired over the regions of paris france and prague czech republic as well as a 35 day coherence image from prague bare soils showed higher coherence compared to forests and urban areas the range of coherence was larger for 28 min pairs perpendicular baseline closer to 2km and stable weather conditions between acquisitions coherence modeling shows that because of the long baseline 1 significant surface decorrelation occurs when slopes are not accounted for in the common band filtering and for variation of topography in the resolution cell and 2 volume decorrelation is significant temporal decorrelation seems to be relevant for vegetation even at the 28 min interval time scale observations and modeled coherence were found to be in good agreement land cover classification using coherence and backscatter has been tested for the paris scene for mapping the four major classes the classification accuracy was 86 when an edge eroded version of the reference land cover map was used it decreases to 68 when the full land cover map was used as reference because of local mismatches between the coherence image and the land cover map and the reduced common band in range the high coherence difference between forests and bare fields suggests the possibility to use the ers envisat coherence for forest nonforest mapping and estimation of biophysical properties of short vegetation coherence decorrelation envisat advanced synthetic aperture radar asar european remote sensing satellite ers land cover synthetic aperture radar interferometry insar

initial observations of lunar impact melts and ejecta flows with the mini rf radar 1 the mini rf radar on the lunar reconnaissance orbiter spacecraft has revealed a great variety of crater ejecta flow and impact melt deposits some of which were not observed in prior radar imaging the craters tycho and glushko have long melt flows that exhibit variations in radar backscatter and circular polarization ratio along the flow comparison with optical imaging reveals that these changes are caused by features commonly seen in terrestrial lava flows such as rafted plates pressure ridges and ponding small 20 km sized craters also show a large variety of deposits including melt flows and ponds two craters have flow features that may be ejecta flows caused by entrained debris flowing across the surface rather than by melted rock the circular polarization ratios cprs of the impact melt flows are typically very high even ponded areas have cpr values between 0 7 and 1 0 this high cpr suggests that deposits that appear smooth in optical imagery may be rough at centimeter and decimeter scales in some places ponds and flows are visible with no easily discernable source crater these melt deposits may have come from oblique impacts that are capable of ejecting melted material farther downrange they may also be associated with older nearby craters that no longer have a radar bright proximal ejecta blanket the observed morphology of the lunar crater flows has implications for similar features observed on venus in particular changes in backscatter along many of the ejecta flows are probably caused by features typical of lava flows

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

geodynamic evolution of the offshore indus basin pakistan the western indian plate passive continental margin a complex meso cenozoic history characterizes the offshore indus basin pakistan including rifting drifting collision transpression and recent inverted extension that is poorly understood we use reflection seismic data to document the geometry of the structures that accommodated the deformation and offshore well data to correlate the sedimentary sequences which were affected by the different tectonic episodes synthetic seismograms have been prepared for calibrating seismic data with well information for identification of key reflections representative of major lithological horizons seismic stratigraphy helped in dividing the sedimentary successions into rifted margin and transpressive margin sequences additionally the basement represented by chaotic and semitransparent reflections and moho discontinuity by moderate amplitude bright reflections are also identified on seismic records syn depositional normal faulting in extensional regime cretaceous oligocene are identified on seismic profiles that converted into strike slip faults in miocene and listric faults in recent sediments forming inverted extensional regime we infer that the basin inversion from extension to inverted extension and transpression occurred in recent times number of depositional features including shelves deltaic deposits canyons and channel levee complexes have been identified that developed in different tectonic episodes five tectonic subsidence curves using back stripping procedure have been calculated in order to constrain the geodynamic evolution of the meso cenozoic sedimentary succession of the offshore indus pakistan the analysis of tectonic subsidence curves covering a time span of 140 ma allowed us to quantify the total subsidence and to document the activities of syn rift and post rift faulting systems different stages in terms of duration and magnitude of subsidence uplift trends have been identified in the evolution of the basin two uplift events are prominent in eocene similar to 40 ma and miocene time similar to 12 ma a rapid resumption of subsidence with non conformity in early palaeocene is seen along the margin

breakup and early seafloor spreading between india and antarctica summary we present a tectonic interpretation of the breakup and early seafloor spreading between india and antarctica based on improved coverage of potential field and seismic data off the east antarctic margin between the gunnerus ridge and the bruce rise we have identified a series of ene trending mesozoic magnetic anomalies from chron m9o 130 2 ma to m2o 124 1 ma in the enderby basin and m9o to m4o 126 7 ma in the princess elizabeth trough and davis sea basin indicating that india antarctica and india australia breakups were roughly contemporaneous we present evidence for an abandoned spreading centre south of the elan bank microcontinent the estimated timing of its extinction corresponds to the early surface expression of the kerguelen plume at the southern kerguelen plateau around 120 ma we observe an increase in spreading rate from west to east between chron m9 and m4 38 54 mm yr 1 along the antarctic margin and suggest the tectono magmatic segmentation of oceanic crust has been influenced by inherited crustal structure the kinematics of gondwanaland breakup and the proximity to the kerguelen hotspot a high amplitude e w oriented magnetic lineation named the mac robertson coast anomaly mca coinciding with a landwards step down in basement observed in seismic reflection data is tentatively interpreted as the boundary between continental transitional zone and oceanic crust the exposure of lower crustal rocks along the coast suggests that this margin formed in a metamorphic core complex extension mode with a high strength ratio between upper and lower crust which typically occurs above anomalously hot mantle together with the existence of the mca zone this observation suggests that a mantle temperature anomaly predated the early surface outpouring steady state magmatic production of the kerguelen lip an alternative model suggests that the northward ridge jump was limited to the elan bank region whereas seafloor spreading continued in the west enderby basin and its sri lankan conjugate margin in this case the mca magnetic anomaly could be interpreted as the southern arm of a ridge propagator that stopped around 120 ma

observation of tropical rain forest trees by airborne high resolution interferometric radar the indonesian radar experiment indrex campaign was executed in indonesia to study the potential of high resolution interferometric airborne radar in support of sustainable tropical forest management severe cloud cover limits the use of aerial photography which is currently applied on a routine basis to extract information at the tree level interferometric radar images may be a viable alternative once radar imaging at the tree level is sufficiently understood it is shown that interferometric height images can contain large height and displacement errors for individual trees but that this problem can be solved to a large extent using models for the vertical distribution of backscatter intensity and an extension of the van cittert zernike theorem the predicted loss of coherence in lay over regions of emergent trees is shown to be in good agreement with the loss of coherence as observed in the high resolution radar data pierson correlation coefficient 0 94 several correction methods for height and displacement errors are proposed it is shown that a simple approach already gives a good correction semi empirical correction models which can be calibrated for forest structure perform even better

estimation of the backscatter vertical profile of a pine forest using single baseline p band pol insar data the vertical backscatter profile of a pine forest constituted by stands of different height is inverted from a single baseline p band pol insar data in order to identify scatterers in the canopy the proposed approach uses the gaussian vertical backscatter profile model which associates an interferometric coherence expression to a vertical scatterers distribution characterized by relative standard deviation and elevation the methodology which uses in situ measurements of forest height and unbiased ground level estimation is applied to hv and vv channels providing accuracy given sufficiently low ground to canopy power ratios inverted backscatter profiles show maximum power converging toward the basis of the tree crown on highest forests where the largest branches are located indicating the high sensitivity of p band measurements to the forest structure and to the vertical biomass distribution over lower stands with larger tree densities the power peak is located in the upper part of the canopy which can be explained by a stronger attenuation in the canopy

sedimentary basins and continental margin processes from modern hyper extended margins to deformed ancient analogues an introduction continental margins and their fossilized analogues are important repositories of natural resources with better processing techniques and increased availability of high resolution seismic and potential field data imaging of present day continental margins and their embedded sedimentary basins in which the majority of these resources are located has reached unprecedented levels of refinement and definition as illustrated by papers in this volume this in turn has led to greatly improved geological geodynamic and numerical models for the crustal and mantle processes involved in continental margin formation from the initial stages of rifting through to continental rupture and break up to the eventual development of a new ocean basin further informing these models and contributing to a better understanding of the features imaged in the seismic and potential field data are observations made on fossilized fragments of exhumed subcontinental mantle lithosphere and ocean continent transition zones preserved in ophiolites and orogenic belts of both palaeozoic and mesozoic age from several different continents including europe south asia and australasia

delineation of delta ecozones using interferometric sar phase coherence mackenzie river delta n w t canada abstract interferometric processing of six c band synthetic aperture radar sar image pairs for the mackenzie river delta shows that phase coherence is more effective than radar backscatter for differentiating willow alder spruce ice and open water similar radar backscattering from vegetation and wind roughened water surfaces can make such distinctions difficult in sar backscatter images in contrast coherence is preserved over surfaces with rigid scattering elements such as leafless woody alder but is lost over temporally unstable surfaces such as open water we find that willow alder display highest coherence followed by spruce frozen lakes and channels and open water respectively this general hierarchy is preserved even when overall image coherence is decreased by increasing temporal and spatial baselines evaluation of spatial thermal noise and temporal components of total observed coherence indicates that temporal decorrelation is a primary control short temporal baselines such as those obtained during the european remote sensing satellite ers 1 day tandem missions are therefore optimal for obtaining maximum differentiation of surface classes

new morphological mapping and interpretation of ejecta deposits from orientale basin on the moon abstract orientale basin is one of the youngest and best preserved multi ring impact basins in the solar system the structure is 950 km across and is located on the western edge of the nearside of the moon the interior of the basin which possesses three distinct rings and a post impact mare fill has been studied extensively using modern high resolution datasets exterior to these rings orientale has an extensive ejecta blanket that extends out radially for at least 800 km from the basin rim in all directions and covers portions of both the nearside and farside of the moon these deposits known as the hevelius formation were first mapped using photographic data from the lunar orbiter iv probe in this study we map in detail the morphology of each distinct facies observed within the orientale ejecta blanket using high resolution lunar reconnaissance orbiter lro wide angle camera wac and narrow angle camera nac images and lunar orbiter laser altimeter lola elevation data we identified 5 unique facies within the ejecta blanket facies a is identified as a region of hummocky plains located in a low lying topographic region between the outer rook and cordillera rings this facies is interpreted to be a mix of crater derived impact melt and km scale blocks of ballistic ejecta and host rock broken up during the modification stage and formation of the cordillera ring facies b is an inner facies marked by radial grooves extending outward from the direction of the basin center this facies is interpreted as the continuous ballistic ejecta blanket facies c consists of inner and outer groupings of flat smooth surfaced deposits isolated in local topographic lows facies d displays characteristic sinuous ridges and lobate extensions facies c and d are interpreted to be impact melt rich materials which manifest as flows and ponds our observations suggest that these facies were emplaced subsequent to the ballistic ejecta blanket most likely during the modification stage of crater formation and flowed and ponded in topographically low lying regions facies e consists of distinct crater chains emanating radially from the basin center and extending from 700 to 1000 km from the center of orientale this facies is considered to be chains of secondary craters formed from large blocks of ballistic ejecta our mapping effort shows that the individual ejecta facies were influenced and controlled to varying degrees by pre existing slopes and topography at the basin scale the overall downslope direction toward the lunar lowlands to the east and southeast of the basin center resulted in large impact melt flows 100 s of kilometers in length while the regional upslope trends in the west and northwest inhibited the development of extensive impact melt flows on a smaller scale it can be observed that ground hugging ejecta collected behind and flowed around high topographic obstacles while diverting into topographic low regions e g around uplifted pre existing crater rims but down into pre existing crater floors the dispersion of the various ejecta facies mapped here also indicates both a direction and an angle for the impact event that formed orientale basin the bilateral distribution of both ballistic and impact melt rich ejecta deposits across a line running northeast southwest suggests the impact occurred from the northeast toward the southwest careful mapping of the secondary impact crater chains facies e shows the development of a forbidden zone lacking these impacts to the northeast as well as a concentration of the longest secondary crater chains to the northwest and southeast perpendicular to the aforementioned line of bilateral ejecta distribution this distribution of secondary impact craters contrasts with the circularity of the basin and suggests that orientale basin was formed by 25 45 impact from the northeast

surface property variations in venusian fluidized ejecta blanket craters abstract a comprehensive study of magellan cycles 1 and 2 radar data from venus reveals surface roughness and dielectric variations associated with fluidized ejecta blanket feb craters that help illuminate styles of flow ejecta emplacement this study develops new procedures of digital unit mapping and polygon filling algorithms using magellan sar altimetry and radiometry data these techniques allow the extraction of radiophysical information for feb crater materials nearby plains and lava flows such as 1 their specific backscatter o behavior relative to each other and to terrestrial lava surfaces 2 average calculated values of emissivity rms slopes corrected reflectivity and the diffuse component of reflectivity and 3 variations in radar properties along longitudinal traverses that are best explained by surface roughness trends at several spatial scales and or dielectric variations backscatter curve slopes of the febs studied here are consistent with surface textures that are transitional between a a and pahoehoelike average surface property values of ejecta units are relatively similar for a given crater but are discernibly different from other craters individual crater ejecta reflectivity and emissivity values are relatively similar to those for the surrounding plains which may suggest a link between plains material and ejecta dielectric properties increasing feb roughness downflow are interpreted to be associated with more lava like flows while decreasing roughnesses are more similar to trends typical of gravity pyroclastic like or debris like flows most commonly feb crater flow materials exhibit transitions from proximal lava melt like flow styles to distal gravity flow like styles some febs show more complicated behavior however or appear to be more dominated by dielectric differences downflow as inferred from correlations between the data sets such transitions may result from changes in local topography or from overlapping of flow lobes during feb emplacement

the breakup of east gondwana assimilating constraints from cretaceous ocean basins around india into a best fit tectonic model published models for the cretaceous sea oor spreading history of east gondwana result in unlikely tectonic scenarios for at least one of the plate boundaries involved and or violate particular constraints from at least one of the associated ocean basins we link east gondwana spreading corridors by integrating magnetic and gravity anomaly data from the enderby basin off east antarctica within a regional plate kinematic framework to identify a conjugate series of east west trending magnetic anomalies m4 to m0 126 7 120 4 ma the mid ocean ridge that separated greater india from australia antarctica propagated from north to south starting at 136ma northwest of australia and reached the southern tip of india at 126 ma sea oor spreading in the enderby basin was abandoned at 115 ma when a ridge jump transferred the elan bank and south kerguelen plateau to the antarctic plate our revised plate kinematic model helps resolve the problem of successive two way strike slip motion between madagascar and india seen in many previously published reconstructions and also suggests that sea oor spreading between them progressed from south to north from 94 to 84 ma this timing is essential for tectonic ow lines to match the curved fracture zones of the wharton and enderby basins as greater india gradually began to unzip from madagascar from 100 ma in our model the 85 east ridge and kerguelen fracture zone formed as conjugate anks of a leaky transform fault following the 100ma spreading reorganization our model also identi es the afanasy nikitin seamounts as products of the conrad rise hotspot

earth based 12 6 cm wavelength radar mapping of the moon new views of impact melt distribution and mare physical properties abstract we present results of a campaign to map much of the moon s near side using the 12 6 cm radar transmitter at arecibo observatory and receivers at the green bank telescope these data have a single look spatial resolution of about 40 m with final maps averaged to an 80 m four look product to reduce image speckle focused processing is used to obtain this high spatial resolution over the entire region illuminated by the arecibo beam the transmitted signal is circularly polarized and we receive reflections in both senses of circular polarization measurements of receiver thermal noise during periods with no lunar echoes allow well calibrated estimates of the circular polarization ratio cpr and the four element stokes vector radiometric calibration to values of the backscatter coefficient is ongoing radar backscatter data for the moon provide information on regolith dielectric and physical properties with particular sensitivity to ilmenite content and surface or buried rocks with diameter of about one tenth the radar wavelength and larger average 12 6 cm circular polarization ratio cpr values for low to moderate tio 2 mare basalt deposits are similar to those of rough terrestrial lava flows we attribute these high values to abundant few centimeter diameter rocks from small impacts and a significant component of subsurface volume scattering an outflow deposit inferred to be impact melt from glushko crater has cpr values near unity at 12 6 cm and 70 cm wavelengths and thus a very rugged near surface structure at the decimeter to meter scale this deposit does not show radar brightness variations consistent with levees or channels and appears to nearly overtop a massif suggesting very rapid emplacement deposits of similar morphology and or radar brightness are noted for craters such as pythagoras rutherfurd theophilus and aristillus images of the north pole show that despite recording the deposition of orientale material byrd and peary craters do not have dense patterns of radar bright ejecta from small craters on their floors such patterns in amundsen crater near the south pole were interpreted as diagnostic of abundant impact melt so the fraction of orientale derived melt in the north polar smooth plains 1000 km farther from the basin center is inferred to be much lower

genetic stratigraphic sequences in basin analysis ii application to northwest gulf of mexico cenozoic basin the northwest gulf of mexico cenozoic sedimentary wedge illustrates the application of genetic stratigraphic sequence analysis and documents several general conclusions 1 sequences defined by regional marine flooding are the principal genetic stratigraphic units of the basin fill continental margins are characterized by repetitive episodes of basin margin offlap punctuated by periods of transgression and marine flooding of the depositional platform 2 continental margin outbuilding is concentrated at one or more shelf edge deltaic depocenters separated by interdeltaic bights depocenters remain fixed during a depositional episode but commonly relocate during transgression and flooding 3 a distinct syndepositional structural style in prograding continental margins results in sporadic uplift of a basin fringing peripheral bulge and accentuates preservation of shelf margin facies along zones of extensional normal faulting and enhanced subsidence 4 genetic stratigraphic sequences commonly reflect an evolving interplay among two or even three variables for example early cenozoic gulf sequences are most closely related to tectonic events of the intraplate source terrane which in turn affect rate and location of sediment supply and basin margin response to loading late cenozoic sequences more closely reflect proposed eustatic cycles

making ends meet in gondwana retracing the transforms of the indian ocean and reconnecting continental shear zones interpretation of the detailed patterns of ocean floor transforms revealed by satellite altimetry enables the creation of the indian ocean to be described quantitatively as four consecutive plate tectonic regimes separated at 200 136 89 and 43 ma each regime is reversed in turn by keeping transform termini coincident and colinear until conjugate points on the margins of pre existing plates regain their pre regime integrity progressive elimination of the indian ocean demonstrable as a smooth computer animation http www kartoweb itc nl gondwana leads to a refined re assembly of the continental fragments of central gondwana that is substantiated by new geological data a sequence of euler interval poles that describes the dispersal of the gondwana fragments time calibrated against available magnetic anomaly data is given the model requires a mid cretaceous position for india s southern tip about 1000 km south of madagascar prior to india s rapid northward migration

presenting meso cenozoic seismic sequential stratigraphy of the offshore indus basin pakistan abstract preserved deformed depositional sequences along passive continental margins are important repositories of natural resources as well as key laboratories for understanding rift drift tectonics with better post signal processing schemes interpretation techniques and potential data imaging sedimentary basins along these margins has reached unique levels of refinement this in turn has led to considerable improvement in unfolding the complex tectono sedimentary history since rifting to basin development in this paper deep reflection seismic coupled with well data and biostratigraphic information have been used to decipher the third order depositional sequences of meso cenozoic succession in western parts of the indian plate passive continental margin offshore indus basin as pioneer research based on morpho tectonic considerations the depositional sequences are divided into syn rift passive margin and post rift stages deformed by steeply dipping normal faults using the principles of classic sequence stratigraphy five third order mappable depositional sequences have been recognized on seismic records that are controlled by regional tectonics and sea level fluctuations coupled with sedimentation type and rates in the region the associated system tracts were recognized and mapped based on genetic reflection terminations on seismic profiles and log motifs and constraint surfaces include sequence boundaries sbs maximum flooding surfaces mfss and transgressive surfaces tss the depositional systems encompass lowstand system tracts lsts transgressive system tracts tsts and highstand system tracts hsts the lsts are composed of shallowing upward lowstand deltas or terraces prograding in the basin ward direction while pinches out landward at preceding depositional shoreline breaks the sand units of tsts are interpreted as shoreface sands deposited in the shelfal part during rising sea levels and hsts are characterized by coarsening and shallowing upward intervals with both fluvial and laterally prograding deltaic deposits a hydrocarbon entrapment model is proposed suggesting an interesting petroleum trap based on the entire course of this research valuable recommendations have been made for answering past exploration failures and future efforts such studies can be applied to worldwide passive margins dominated by third order sequences with complex sediments tectonic interplay

modeling of fluidized ejecta emplacement over digital topography on venus the flow computer model of mcewen and malin 1989 modified for application to the study of venus fluidized ejecta blankets febs demonstrates that relatively low viscosities yield strengths and initial velocities are required to duplicate the observed flow paths of the outflow materials the model calculates the velocities and simulated flow paths of gravity flows over magellan topography the model is formulated to determine flow movements from initial conditions gravitational acceleration and resistance to motion as described by coulomb viscous and turbulent resistance forces successful duplication of observed feb flow paths has been achieved for the feb craters addams isabella and cochran when used as a simple energy line model the model requires low coefficients of friction to extend febs to near their observed termini in the synthetic aperture radar sar imagery although the resulting straight flow lines do not follow the observed flow paths well for bingham flow the model requires low values of viscosity and yield strength which are more similar to pyroclastic or debris flows than basaltic lavas flows of 100 m depth require 1 to 2 orders of magnitude higher values of both viscosity and yield strength than 10 m deep flows the complicated nature of the flow lines for the low velocity model suggests that febs were probably emplaced under variably laminar and turbulent flow conditions where underlying topography influenced both the direction and energy of flow materials

review and revision of cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale planktonic foraminifera are widely utilized for the biostratigraphy of cretaceous and cenozoic marine sediments and are a fundamental component of cenozoic chronostratigraphy the recent enhancements in deep sea drilling recovery multiple coring and high resolution sampling both offshore and onshore has improved the planktonic foraminiferal calibrations to magnetostratigraphy and or modified species ranges this accumulated new information has allowed many of the planktonic foraminiferal bioevents of the cenozoic to be revised and the planktonic foraminiferal calibrations to be reassessed we incorporate these developments and amendments into the existing biostratigraphic zonal scheme in this paper we present an amended low latitude tropical and subtropical cenozoic planktonic foraminiferal zonation we compile 187 revised calibrations of planktonic foraminiferal bioevents from multiple sources for the cenozoic and have incorporated these recalibrations into a revised cenozoic planktonic foraminiferal biochronology we review and synthesize these calibrations to both the geomagnetic polarity time scale gpts of the cenozoic and astronomical time scale ats of the neogene and late paleogene on the whole these recalibrations are consistent with the previous work however in some cases they have led to major adjustments to the duration of biochrons recalibrations of the early middle eocene first appearance datums of globigerinatheka kugleri hantkenina singanoae guembelitrioides nuttalli and turborotalia frontosa have resulted in large changes in the durations of biochrons e7 e8 and e9 we have introduced upper oligocene zone o7 utilizing the biostratigraphic utility of paragloborotalia pseudokugleri for the neogene period major revisions are applied to the fohsellid lineage of the middle miocene and we have modified the criteria for recognition of zones m7 m8 and m9 with additional adjustments regarding the globigerinatella lineage to zones m2 and m3 the revised and recalibrated datums provide a major advance in biochronologic resolution and a template for future progress of the cenozoic time scale

maastrichtian climate productivity and faunal turnovers in planktic foraminifera in south atlantic dsdp sites 525a and 21 abstract stratigraphic faunal and isotopic analyses of the maastrichtian at dsdp sites 525a and 21 in the south atlantic reveal a planktic foraminiferal fauna characterized by two major events an early late maastrichtian diversification and end maastrichtian mass extinction both events are accompanied by major changes in climate and productivity the diversification event which occurred in two steps between 70 5 and 69 1 ma increased species richness by a total of 43 and coincided with the onset of major cooling in surface and bottom waters and increased surface productivity the onset of the terminal decline in maastrichtian species richness began at 67 5 ma and the first significant decline in surface productivity occurred at 66 2 ma coincident maximum cooling to 13 c in surface waters and the reduction of the surface to deep temperature gradient to less than 5 c major climatic and moderate productivity changes mark the mass extinction and the last 500 kyr of the maastrichtian between 200 and 400 kyr before the k t boundary surface and deep waters warmed rapidly by 3 4 c and cooled again during the last 100 kyr of the maastrichtian surface productivity decreased only moderately across the k t boundary species richness began to decline during the late maastrichtian cooling and by k t boundary time the mass extinction had claimed 66 of the species viewed within the context of maastrichtian climate and productivity changes the k t mass extinction could have resulted from extreme environmental stress even without the addition of an extraterrestrial impact

forest height inversion using high resolution p band pol insar data in this paper a high resolution p band pol insar data set acquired by the airborne ramses system over pine forest stands of different height is investigated a significant penetration depth in all the polarimetric channels and a wide range of polarimetric phase center heights are observed attesting of an interaction of the radar waves with different forest structural elements the main objective of this paper concerns forest height inversion at p band first forest modeling assumptions are evaluated using a priori information such as ground level and forest height measurements the full extend of the forest height is shown to be responsible of the volume decorrelation and a significant orientation effect is clearly identified over the highest stands as a consequence the oriented volume over ground model ovog is determined to be the most appropriated model for the forest height inversion at p band the ground contribution is present in all the polarimetric channels due to the important penetration at this frequency to overcome this difficulty a time frequency optimization method based on sublook decomposition is developed to separate the pure ground and canopy contributions allowing forest height estimation with ovog with an rms error on the order of 2 m in the last section of this paper a sensitivity analysis of the inversion with respect to two important system parameters the signal to noise ratio and the resolution is presented leading to a discussion on the inversion robustness in spaceborne conditions where these system parameters are the most deteriorated as compared to airborne configurations

controls on the paleogene carbonate platform growth under greenhouse climate conditions offshore indus basin abstract during the paleocene and eocene the western continental margin of the indian plate was an equatorial province characterized by widespread attached and isolated carbonate platforms using high resolution seismic data combined with sedimentological data and log motifs this study presents the stratigraphic evolution the morphological features and the distributions of these isolated carbonate platforms which are located on ne sw oriented basement highs and volcanic ridges linked to the reunion hotspot trace seismic stratigraphy allows defining seven seismic units in the platform succession stratal stacking patterns indicative of phases of aggradation and of large scale backstepping alternate with horizons interpreted to indicate repeated phases of emersion the onset of platform growth and the further platform development were mainly controlled by the subsidence following the deccan volcanism and the opening of carlsberg ridge platforms are asymmetrical in the section with the eastern aggrading margins interpreted as windward and the western margins as leeward the leeward margins which through time stepped back appear as structurally modified by basement induced faults fault blocks movement also partially influenced the internal platform geometries and the facies distribution change in the rate of subsidence possibly augmented the relative sea level rise during the early to middle eocene and hence contributed to the demise of the isolated carbonate platforms isolated carbonate platforms are stratigraphically age equivalent to the laki ghazij lithostratigraphic unit of the contemporaneous carbonate shelf as per our knowledge this carbonate system is the best known seismic scale example of greenhouse carbonate system thriving during the paleocene eocene

revised and synthetic apparent polar wander paths of the african eurasian north american and indian plates and true polar wander since 200 ma we have reviewed paleomagnetic data available for the eurasian african north american and indian plates over the last 200 ma selection criteria are those generally accepted with an emphasis on evidence for lack of remagnetization accurate dating and proper structural analysis this results in 23 35 51 and 2 poles for eurasia africa north america and india respectively we believe that this limited set of higher quality data is more likely to reveal key features of apparent polar wander apw paths than averaging of larger data sets involving less stringent selection criteria we propose and describe revised apw paths but more importantly we next use relative motion models to transfer all data in a common reference frame we find good agreement between transferred data when they are averaged separately for each plate in independent 20 ma windows this is a check on consistency of paleomagnetic data kinematic models and of the geocentric dipole hypothesis transferred data from all plates are averaged in 20 ma windows to generate synthetic apw paths for all plates studied these synthetic paths are in agreement with the original revised apw paths that use only data from a single plate moreover both geographic and time resolution are improved spatial confidence intervals are of the order of 5 the synthetic paths display interesting features such as a previously ill recognized apw loop for eurasia paleomagnetic and hotspot apw are next compared and a determination of true polar wander tpw is derived we find significant tpw amounting to over 20 in the last 200 ma tpw appears to be episodic with a standstill between 180 and 110 ma there is general agreement with a previous study of livermore et al 1984 the tpw standstill appears to correlate with a time of decreasing reversal frequency ending with the cretaceous long normal superchron other periods of fast tpw would seem to correspond to increasing reversal frequency however it is suggested that the major tpw hairpin at 50 ma might correspond to the collision of india with eurasia tentative correlations with core or mantle indicators can be understood as a result of couplings between the core mantle and lithosphere we believe primarily related to episodic evolution of the d layer

constraints on the collision and the pre collision tectonic configuration between india and asia from detrital geochronology thermochronology and geochemistry studies in the lower indus basin pakistan abstract knowledge of the timing of india asia collision is a fundamental prerequisite for understanding the evolution of the himalayan tibetan orogen and its role in global climate oceanic chemistry and ecological evolution despite much active research the basic pre collision tectonic configuration and the timing of terminal india asia suturing remain debated for example debates regarding when and how the intervening kohistan ladakh arc was sutured with india and asia still remain elusive some models propose the arc collided with asia at about 100 ma with india asia collision at ca 55 ma whilst a newer model proposed the arc s collision with india at 50 ma and subsequently with asia at 40 ma another example is the recent proposition that an oceanic greater india basin separated the tethyan himalaya microcontinent from the remaining indian plate until 20 25 ma with the consumption of this oceanic basin marking the final collision at this time these controversies relate to whether the commonly documented 50 ma contact represents the terminal india asia suturing or the amalgamation between various arcs or microcontinents with india or asia here we present an integrated provenance study of geochronology thermochronology and geochemistry on the late cretaceous pleistocene sediments from the lower indus basin on the indian plate the detrital zircon u pb and fission track data show a reversal in sediment source from a pure indian signature to increasing inputs from the suture zone and the asian plate between the middle paleocene and early oligocene the nd and sr isotopes narrow down this change to 50 ma by revealing input of asian detritus and the establishment of a nd sr isotopic pattern similar to the present day indus fan by 50 ma with no significant variations up section contrary to what might be expected if later major collisions had occurred our isotopic data indicate that greater india was occupied by a fluvial deltaic system analogous to the present day indus and named as the paleo indus which has been transporting asian detritus southward across the suture zone and kohistan ladakh arc since 50 ma suggesting no other ocean basins intervened between india and asia after this time in this region our data require that in the west the india asia collision were accomplished by 50 ma

a survey of temporal decorrelation from spaceborne l band repeat pass insar abstract in this paper we quantify the effects of temporal decorrelation in repeat pass synthetic aperture radar interferometry insar temporal decorrelation causes significant uncertainties in vegetation parameter estimates obtained using various insar techniques which are desired on a global scale because of its stochastic nature temporal decorrelation is hard to model and isolate in this paper we analyze temporal decorrelation statistically as observed in a large swath of sir c l band insar data collected over the eastern united states with a repeat pass duration of one day in october 1994 and a near zero perpendicular baseline the very small baseline for this particular pair makes the effect of volumetric scattering on correlation magnitude statistics nearly imperceptible allowing for a quantitative analysis of temporal effects alone the swath analyzed in this paper spans more than a million hectares of terrain comprised primarily of deciduous and evergreen forests agricultural land water and urban areas the relationships of these different land cover types phenology and weather conditions i e precipitation and wind on the measures of interferometric correlation is analyzed in what amounts to be the most geographically extensive analysis of this phenomenon to date

c band repeat pass interferometric sar observations of the forest properties of ers 1 c band repeat pass interferometric sar information for a forested area are studied the intensity information is rather limited but including coherence and effective interferometric sar insar height more information about the forest parameters can be obtained via satellite such information is also important for correction of insar derived topographic maps coherence properties have been used to identify forested nonforested areas and the interferometric effective height of the forest determined by comparison to a dem of the area the authors have developed a model to relate basic forest properties to insar observations these show that the coherence and interferometric effective height of a forested area change between image pairs the model demonstrates how these properties are related to the temporal decorrelation and the scattering from the vegetation canopy and the ground surface gaps in the vegetation are found to be important in the characterization of boreal forests

composition of seismic facies a case study in this case study we used simulated seismic data from outcrops on svalbard to analyze what seismic facies are composed of what the dominating factors in forming the facies are and which consequences this has for the interpretation results seismic facies analyses can be used to interpret environmental setting depositional processes and lithology here we found that noise is the most important factor in forming the seismic facies noise is defined as all reflections that cannot be ascribed directly to the reservoir model effects from overburden and processing dominated and the low frequency content of the seismic section complicated the seismic facies analyses the main reason for this is that the analysis relies heavily on identified internal patterns and low angle terminations such patterns and terminations are easily created by the seismic method itself by overburden effects and by artifacts generated when processing the data external form strong amplitudes and continuous reflections are robust seismic observations whereas the internal pattern and terminations are commonly deceptive identification of boundaries based on predefined patterns of terminations does not work here and uncritical use of seismic facies analysis in this interpretation case will create wrong reservoir models because of the size of the outcrops the results from this analysis are relevant for reservoir scale seismic interpretation and detailed interpretation for prospect evaluation in mature basins for seismic interpretation at a more regional scale it is probably less relevant

single baseline polarimetric sar interferometry examines the application of single baseline polarimetric sar interferometry to the remote sensing and measurement of structure over forested terrain for this a polarimetric coherent scattering model for vegetation cover suitable for the estimation of forest parameters from interferometric observables is introduced discussed and validated based on this model an inversion algorithm which allows the estimation of forest parameters such as tree height average extinction and underlying topography from single baseline fully polarimetric interferometric data is addressed the performance of the inversion algorithm is demonstrated using fully polarimetric single baseline experimental data acquired by dlr s e sar system at l band

foraminifera from the borehole altdorf se germany proxies for ottnangian early miocene palaeoenvironments of the central paratethys abstract during the ottnangian early miocene the shallow epicontinental sea of the upper marine molasse in the western and central paratethys realm experienced major sea level fluctuation leading to significant environmental changes however the effects of these changes remain largely unexplored because detailed palaeoenvironmental analyses of the respective time interval are scarce we here present a thorough analysis of the benthic foraminiferal composition 36 samples 5616 individuals and 90 taxa from a 105 25 m thick marine ottnangian succession of the borehole altdorf and from two coeval outcrops neuhofen oberschwarzenbach all located in the western central paratethys studies on the planktonic foraminifera and calcareous nannoplankton were conducted as well we show that benthic foraminiferal assemblages clearly differ with regard to species composition diversity indexes relative abundances of infauna epifauna and oxygen indicators we introduce five foraminiferal biofacies which together are suggestive of a transgressive regressive development and several distinct environmental changes from the early to middle ottnangian the planktonic foraminiferal assemblages from altdorf and the central paratethys suggest cold temperate surface water however high nutrient availability and taphonomic factors such as selective dissolution could also have affected the planktonic assemblages in most samples the relative abundance of infaunal epifaunal benthic foraminifera planktonic foraminifera and calcareous nannoplankton clearly indicates nutrient rich waters we did not find indicators for upwelling as a possible source for the nutrient flux and therefore assume that the high nutrient levels indicate large scale river influx in a humid climate based on our foraminiferal biofacies we postulate the presence of a particularly high fluviatile runoff and high organic matter supply resulting in a moderate oxygen depletion of marine bottom waters for the period of relative sea level highstand in the early ottnangian strong oxygen depletion of bottom waters occurs in the middle ottnangian and is mainly caused by salinity stratification and a reduced water exchange to the open ocean during that time moreover our data demonstrate that p b ratios for early and middle ottnangian samples only partially support the palaeobathymetric reconstructions based on the benthic foraminifera we suggest that fluviatile input and estuarine circulation strongly affected the relative abundances of planktonic foraminifera besides tidal and other marine currents

understanding oblique impacts from experiments observations and modeling natural impacts in which the projectile strikes the target vertically are virtually nonexistent nevertheless our inherent drive to simplify nature often causes us to suppose most impacts are nearly vertical recent theoretical observational and experimental work is improving this situation but even with the current wealth of studies on impact cratering the effect of impact angle on the final crater is not well understood although craters rims may appear circular down to low impact angles the distribution of ejecta around the crater is more sensitive to the angle of impact and currently serves as the best guide to obliquity of impacts experimental studies established that crater dimensions depend only on the vertical component of the impact velocity the shock wave generated by the impact weakens with decreasing impact angle as a result melting and vaporization depend on impact angle however these processes do not seem to depend on the vertical component of the velocity alone finally obliquity influences the fate of the projectile in particular the amount and velocity of ricochet are a strong function of impact angle

repeat pass sar interferometry over forested terrain repeat pass synthetic aperture radar sar interferometry provides the possibility of producing topographic maps and geocoded as well as radiometrically calibrated radar images however the usefulness of such maps and images depends on our understanding of how different types of terrain affect the radar measurements it is essential that the scene coherence between passes is sdcient in this paper we derive a general system model including both radar system and scene scattering properties the model is used to interpret measurements over a forested area where the scene coherence varies between 0 2 and 0 5 the coherence is found to be sensitive to temperature changes around 0 c but surprisingly insensitive to wind speed the interferometric height discontinuity at the forest to openfield boundary shows good agreement with in situ tree height measurements for a dense boreal forest but is observed to decrease for a less dense forest this suggests the possibility of estimating bole volume from the interferometric tree height and a ground dem the decrease of scene coherence over a dense forest with increasing baseline is also used to estimate the effective scattering layer thickness

change detection on alaska s north slope using repeat pass ers 1 sar images measurements of the c band wavelength 5 cm radar cross section of an area in the brooks range foothills on the north slope of alaska using images from the ers 1 satellite that show significant temporal changes occur these changes are strongly correlated with elevation and hill slope orientation and are greatest on some of the elevated areas and weaker in river drainages by constructing difference images using various image pairs and by analyzing climatological and hydrological data from the site it is concluded that the radar backscatter changes are largely due to changes in soil and vegetation liquid water content induced by freeze thaw events the correlation with topography in the difference images arises from the dependence of vegetation organic layer thickness and volumetric water content on hill slope position and orientation these results demonstrate the viability of radar backscatter intensity comparisons using repeat pass images as a means of change detection

timing of india asia collision geological biostratigraphic and palaeomagnetic constraints 1 a range of ages have been proposed for the timing of india asia collision the range to some extent reflects different definitions of collision and methods used to date it in this paper we discuss three approaches that have been used to constrain the time of collision the time of cessation of marine facies the time of the first arrival of asian detritus on the indian plate and the determination of the relative positions of india and asia through time in the qumiba sedimentary section located south of the yarlung tsangpo suture in tibet a previous work has dated marine facies at middle to late eocene by far the youngest marine sediments recorded in the region by contrast our biostratigraphic data indicate the youngest marine facies preserved at this locality are 50 6 52 8 ma in broad agreement with the timing of cessation of marine facies elsewhere throughout the region double dating of detrital zircons from this formation by u pb and fission track methods indicates an asian contribution to the rocks thus documenting the time of arrival of asian material onto the indian plate at this time and hence constraining the time of india asia collision our reconstruction of the positions of india and asia by using a compilation of published palaeomagnetic data indicates initial contact between the continents in the early eocene we conclude the paper with a discussion on the viability of a recent assertion that collision between india and asia could not have occurred prior to 35 ma

tectonic subsidence flexure and global changes of sea level tectonic models for the evolution of passive continental margins predict that following rifting sediments should progressively onlap basement at the edge of a margin as the lithosphere cools and increases its flexural rigidity with age the pattern of modelled onlap is strikingly similar to that used by vail and colleagues to estimate sea level rise through geological time this similarity suggests that major portions of stratigraphical sequences at margins may have a tectonic rather than eustatic control the patterns of onlap used by vail and colleagues may be widespread however because several widely separated passive margins rifted at similar times but they are unlikely to be worldwide

studies of multibaseline spaceborne interferometric synthetic aperture radars the authors have utilized a set of seasat synthetic aperture radar sar data that were obtained in nearly repeat ground track orbits to demonstrate the performance of spaceborne interferometric sar insar systems an assessment of the topography measurement capability is presented a phase measurement error model is described and compared with the data obtained at various baseline separations and signal to noise ratios finally the implications of these results on future spaceborne insar design are discussed

change detection for thematic mapping by means of airborne multitemporal polarimetric sar imagery the paper addresses the detection of changes in multitemporal polarimetric radar images focusing on small objects and narrow linear features the images were acquired at c and l band by the airborne emisar system it is found that the radar intensities are better suited for change detection than the correlation coefficient and the phase difference between the co polarized channels in the case of linear features there is no obvious difference between the c and l bands and slight variations of the flight tracks are acceptable at look angles larger than 35 degrees theoretical detection thresholds are evaluated from the statistical distribution of the intensity ratio due to speckle for the linear features and for urban environments the observed thresholds are larger than the theoretical predictions this is interpreted as an effect of radar intensity variations on length scales smaller than the spatial image resolution the signature of urban areas is very sensitive to deviations between the flight tracks and the sensitivity is larger at c band than at l band on the other hand the intensity contrast between buildings and the urban background is smaller at l band and larger at c band for change detection thresholds may have to be chosen separately for each object class because the intensity ratios of different object classes vary differently as a function of time

unfolding impacts of freaky tectonics on sedimentary sequences along passive margins pioneer findings from western indian continental margin offshore indus basin abstract the western passive continental margin of the indian plate wcmi serves as an elegant laboratory for understanding the syn sedimentary rift drift tectonics preserving a variety of episodic structural deformations and complex sedimentary infill here we present a multidisciplinary study on offshore indus basin oib that is less investigated compared to adjacent marginal basins along wcmi reflection seismic gravity borehole and biostratigraphic data have been used to reconstruct the tectono sedimentary history of the meso cenozoic succession in oib seismic based dynamic stratigraphy helped in mapping seven different depositional sequences grounded on morpho tectonic considerations the seismic expression of these sequences provided an idea of the depositional styles with different tectonic episodes since rifting in jurassic to basin inversion in miocene continued to present time the oib initially filled from the north with the sediments rapidly prograding southwards in general the basin deepens in the central and northwestern part where the formations achieve maximum depths the analysis of 3d structural models revealed that the region experienced poly phase deformation from the late cretaceous to recent times that include steeply dipping normal faults horst and graben half graben half graben with growth faulting flower structures anticline syncline and uplift with an angular unconformity the most remarkable tectonic activity happened at the early miocene and resulted in the reactivation of extensional faults into strike slip faults giving rise to a spectacular structural inversion due to transform movement between indian and arabian plates that continues to present day the most predominant faults are oriented in s20 50 e with azimuth as 120 160 and the maximum dip angles are 80 in the southwest flank of the basin the main fault trend is s20 e n20 w and dip angles ranging between 40 and 80 and above a thick crust and the ocean continent transition oct is imaged with massive felsic mafic and ultramafic intrusions by the help of forward gravity modeling an initial onset of syn rift tectonic subsidence between 90 and 68 ma with a post rift general increase between 68 and 54 ma is comprehended while two uplift events at 40 ma and 18 ma are documented through backstripping analysis it is inferred that the region is rapidly under complex structural inversion with growing folding faulting and flowering structures this study could help in explaining the unanswered reasons of structural complexities depositional styles and basin inversion along worldwide passive margins

investigating attenuation scattering phase center and total height using simulated interferometric sar images of forested areas the objective of this paper is to examine the link between the attenuation coefficients and the interferometric phase center heights for several frequencies from p to l band and to study the extent to which it depends on the canopy architecture and description this paper relies on the use of a coherent and full polarimetric scattering model which simulates the fields backscattered by a forested area in the first part we study the behavior with a frequency of the interferometric phase center heights and in the second part we focus on the attenuation coefficients then we compare the behaviors of these two quantities and we propose to empirically derive a relation between these two quantities and the mean forest height finally we investigate if a change in the initial forest or radar configuration has an impact on the determination of this relation

paleogeographic maps of the continents bordering the indian ocean since the early jurassic paleomagnetic data from the african plate from the early jurassic onward are critically re evaluated and updated resulting in a set of 30 paleopoles from which an apparent polar wander path is derived using 20 ma intervals this path is then used in conjunction with kinematic models of the indian and atlantic oceans to place other continents bordering the indian ocean eurasia india islands and plateaus madagascar seychelles mascarene and blocks involved in the collision of india with eurasia south tibet indochina in an absolute paleogeographic frame fixed with respect to africa paleogeographic maps are presented for the early jurassic pre breakup the jurassic cretaceous boundary anomaly ml5 the early cretaceous m2 the late cretaceous a 34 the cretaceous tertiary boundary a 29 the early eocene a 24 the middle eocene a 21 and the oligocene miocene boundary a 6 observed and predicted paleomagnetic directions for landmasses other than africa i e for western europe china korea india and australia which are not used in deriving the maps are found to be in very satisfactory agreement the quality of reconstructions as measured by rms discrepancies between observed and predicted paleolatitudes is of the order of 5 the main features of the paleogeographic maps are discussed with the aim of relating oceanic and on land geodynamic events the constraints provided by tibetan data on the india asia collision and the 20 ma reorganization of geology and plate boundaries in a band extending from the south china sea through tibet to the red sea system are discussed in more detail we emphasize the episodic nature of the breakup of gondwanaland and formation of the indian ocean and subsequent interaction with eurasia in which six major discrete events are identified separated by 30 ma phases of rather uniform plate motion

monitoring very slow slope movements by means of sar interferometry a case study from a mass waste above a reservoir in the otztal alps austria the application of radar interferometry to detect slope movements on the order of millimeters to centimeters per year is demonstrated the deformation field of a slope above a hydropower reservoir in the austrian alps was derived from sar interferometric pairs of the satellites ers 1 and ers 2 acquired between july 1992 and august 1998 above the treeline it was possible to map the motion from interferograms covering time spans up to three years whereas ground based geodetic measurements focussed on the movements of the lower slope section the interferometric analysis shows that the mass wasting processes affect the entire slope of 1000 m vertical extent significant interannual differences of the displacement rates became apparent which were found to be related to the pattern of summer rainfall

two different supply styles of crater outflow materials on venus inferred from numerical simulations over dems abstract the three dimensional numerical simulation code for nonisothermal bingham fluid was applied to four typical crater outflows on venus to estimate emplacement styles of outflow materials we have succeeded in reproducing emplacement features qualitatively over digital elevation models dems obtained by the magellan spacecraft and we have shown that outflow materials can be formed by melts of basaltic crust therefore the presence of crater outflows may not be evidence of the presence of previously suggested fluid materials such as komatiite or carbonatite although we failed to model the very low viscosity flow numerically estimated supply rates of flow materials are categorized into two types a catastrophic style and a gentle style markham and isabella crater outflows are examples of catastrophic styles and the flow materials required to form them were probably supplied at higher rates than 1010 m3 s and the durations of material supply were less than 100 s this very high supply rate is difficult to attribute to any volcanic process because typical eruption rates of terrestrial volcanic flows are less than 8 or 9 orders of magnitude lower than that such a style of emplacement is more plausibly considered as a result of the impact itself for example a catastrophic debris flow or a vapor cloud triggered by the impact on the other hand supply rates of willard and xantippe outflows which are considered gentle style flows were estimated to be about 104 m3 s and the durations were more than 105 s such a gentle style of outflow emplacement is probably not a direct result of the impact but is rather due to a secondary process possibly segregation and drainage of impact melt materials from within previously emplaced ejecta materials or post impact volcanism

shoshonites in southern tibet record late jurassic rifting of a tethyan intraoceanic island arc abstract detailed field mapping combined with a petrologic and geochemical investigation of the zedong terrane within the yarlung tsangpo suture zone provides insights to the evolution of now mostly subducted portions of tethys during the late jurassic the terrane is dominated by volcanic rocks of shoshonitic affinity which were erupted in a submarine oceanic island arc setting the volcanic island arc was built on a basement of oceanic crust and the shoshonites locally overlie a thin section of pillowed island arc tholeiites and red ribbon bedded radiolarian cherts geochemistry of the shoshonites suggests that their development occurred in a setting analogous to that of late miocene to early pliocene fiji and was associated with an arc rifting we speculate that this event may have been a far field response to developments associated with gondwana breakup

the role of pre impact topography in impact melt emplacement on terrestrial planets abstract on terrestrial planets flow like deposits of impact melt are commonly found exterior to fresh impact craters often these deposits are asymmetric about the crater rim and the direction of flow may relate to either the pre impact topography or the impact azimuth in this work we seek to determine the primary mechanism responsible for impact melt emplacement on two very different terrestrial worlds the moon and venus newly derived stereo topography data allows us to investigate the role of pre impact topography in melt emplacement on venus for the first time we determine that pre impact topography plays an important role in melt emplacement around complex craters on the moon but not on venus this difference may relate to the differences in gravity and hence crater depth and melt volume on the two worlds melt trapped in the relatively deep lunar craters may require additional momentum to be pushed over the crater rim and therefore emerges preferentially from the region of rim crest low this added momentum might come from uplift during the crater modification stage for the shallower craters on venus the downrange momentum imparted in oblique impacts may be sufficient to push the melt up and over the crater rim explaining the correlation between melt direction and impact azimuth understanding the emplacement of impact melt on terrestrial planets of different sizes and geologic histories provides added insight into the impact cratering process

temporal stability of x band single pass insar heights in a spruce forest effects of acquisition properties and season solberg svein weydahl dan johan astrup rasmus andreas temporal stability of x band single pass insar heights in a spruce forest effects of acquisition properties and season ieee transactions on geoscience and remote sensing 2014 volum 53 3 s 1607 1614