textural characteristics and genesis of the aeolian sediments in the kuwaiti desert several types of aeolian deposits have been recognized in kuwait a smooth sand sheets that resemble desert floor sand b immobile sands that include rugged vegetated sand sheets and wadi fill deposits and c mobile sands that form active sand sheets and sand dunes simple size frequency curves illustrate the genetic relationship between the various aeolian sediment types the four size parameters namely mean size sorting skewness and kurtosis were calculated scatter plot diagrams of sorting versus mean size and sorting versus kurtosis are effective in differentiating smooth sand sheet deposits from dune sands active sand sheet deposits can also be recognized because they are usually located between the two end members smooth sand sheets and dune sands size parameters change with location regardless of their types coarsening and positive skewness usually increase downwind mineralogical and textural characteristics of the aeolian deposits in kuwait revealed that they are mostly derived from the lower mesopotamian muddy flood plain deposits the sand fraction of the al dibdibba gravelly deposits and the disintegrated material from calcretic and gypcretic duricrusts distribution of depositional and deflational areas indicates that the northern desert of kuwait is characterized by a positive sand budget whereas the southern desert has a negative sand budget

resolving three dimensional surface displacements from insar measurements a review abstract one dimensional measurement along the line of sight los direction has greatly limited the capability of insar technique in the investigation of surface displacements and their dynamics in recent years great efforts have been made to resolve complete three dimensional 3 d displacements from insar measurements this contribution is intended to provide a systematic review of the progress achieved in this field based on an analysis of the insar los measurements we first cover two commonly used techniques i e offset tracking and multi aperture insar mai with which the surface displacement in the azimuth direction can be measured together with the los displacement several methods for mapping 3 d displacements using insar measurements are subsequently presented and categorized into three groups i combination of multi pass los and azimuth measurements ii integration of insar and gps data and iii prior information assisted approaches the strengths and weaknesses of each method are analyzed to show the applicability of each method to specific 3 d displacement mapping cases in hope to provide a useful guidance in choosing a suitable approach accordingly finally suggestions for resolving the challenging issues and outlook of future research are given

the effects of soluble salts on the threshold shear velocity of fine sand wind tunnel tests were carried out to investigate the effects of two soluble salts nacl and kci on the threshold shear velocity of a well sorted fine sand a sensitive laser monitoring system was used to detect initial grain motion during the tests results indicate that even small amounts of soluble salt can significantly increase the threshold velocity of the sand because of cement like bonds formed between grains that tend to hold individual particles in place however with increasing concentration the salt crystal growth causes the initially smooth sand surface to develop an irregular frothy texture which also directly affects the threshold shear velocity this is indicated by increased scatter of data on the threshold shear velocity surface salt concentration plots for both nacl and kcl although data scatter is evident significant exponential relationships do exist between threshold shear velocity and surface salt concentration in each case

wind sedimentation in the jafurah sand sea saudi arabia the jafurah sand sea of the eastern province of saudi arabia extends along the arabian gulf coastline from kuwait in the north to the rub al khali in the south a distance of about 800 km sand drifts southward to south eastward from regions of high wind energy in the north to low wind energy in the south the aeolian landscape is zoned with areas of deflation transport and deposition from north to south drift rates in the zone of transport near abqaiq range from 2 m3 m w 1 yr 1 on sabkhas to 29 m3 m w 1 yr 1 on the crests of dunes average drift rates of approximately 18 m3 m w 1 yr 1 observed during the study can cause about 1 m of accumulation per 5500 yr in a 100 km zone of deposition downwind not including the bulk transport represented by the forward advance of dunes dune advance ranged from 23 m 2 9 m high dune to 3 m 23 m high dune during april october 1980 the study area consists of dune interdune sand sheet and siliciclastic sabkha terrains each of which is characterized by differing drift rates and differing rates of erosion or deposition sedimentation occurs by lateral movement of dunes and interdunes and vertical accretion by sand sheets and sabkhas

sm nd age of kambalda and kanowna greenstones and heterogeneity in the archaean mantle a precise sm nd age of 2 790 30 myr and an initial ratio corresponding to nd 3 4 0 6 has been determined for the kambalda sequence from the eastern yilgarn block of western australia the high initial 143nd 144nd implies a long lived light rare earth element depleted high sm nd source for the kambalda volcanics and therefore provides definitive evidence for ancient heterogeneities in the archaean mantle

kalman filter based approach for multisensor multitrack and multitemporal insar a kalman filter based approach is presented for resolving 3 d surface displacements using multisensor multitrack and multitemporal interferometric synthetic aperture radar sar measurements measurements from each interferogram are projected into the three reference directions and combined in the kalman filter model with displacements determined from previous interferograms to produce updated displacement measurements both simulated and real data sets are used to test the proposed approach it is found that the method works well when the measurement noise is low the displacements in the north direction however are much lower in accuracy than those in the other two directions and even become unstable when the measurement noise is high due to the polar orbiting imaging geometries of the current satellite sar sensors

archean banded iron formations yilgarn block western australia banded iron formation is a widely distributed although relatively minor lithology in the archean yilgarn block western australia occurring in supracrustal sequences composed mainly of metamorphosed volcanogenic rocks in the northern and eastern parts of the yilgarn block and also in highly deformed and metamorphosed predominantly metasedimentary sequences in the gneissic terrain in the southwest in the central part of the yilgarn block structural mapping and stratigraphic reconstruction indicates that individual banded iron formation units extend over an area of at least 40 x 60 km and could extend over a much larger area most banded iron formation units appear to be 5 to 50 m thick and units of 100 to 150 m are uncommon three scales of layering occur in iron formation units a interlayering of banded iron formation and fe shale fe shales range in thickness from several millimeters to 5 to 6 m b mesobanding is the most prominent structure in the banded iron formations c millimeter scale laminations including microbanding occur in both banded iron formation and fe shales other structures in the banded iron formation include pods macules and small spheroidal nodules despite modification by metamorphic and deformation processes which among other effects have caused thinning of mesobands all the structures can readily be equated with those in the hamersley basin iron formations there is a wide range in metamorphic grade at the lowest grades banded iron formation contains quartz magnetite greenalite stilpnomelane minnesotaite siderite and ankerite fe shales contain chamosite stilpnomelane siderite and pyrite the highest grades are characterized by quartz magnetite clinopyroxene orthopyroxene in iron formation and hornblende almandine or biotite assemblages in fe shale mineral assemblages are essentially identical to those in many metamorphosed proterozoic iron formations the bulk chemical compositions of the yilgarn block iron formations are very similar to other precambrian iron formations from very different stratigraphic settings fe shales have highly variable compositions characterized by a marked positive al 2 o 3 tio 2 correlation and high cr contents the similarity in the bulk chemical composition of iron formations in the yilgarn block and other precambrian sequences implies that deposition of these iron formations occurred in very similar chemical environments it is suggested that although fe shales may be related in some way to volcanic activity the main constituents of the banded iron formations are not directly derived from volcanic sources banded iron formations appear to have been precipitated from ocean waters which relative to younger oceans contained higher concentrations of fe and si in solution

simulation of the supersar multi azimuth synthetic aperture radar imaging system for precise measurement of three dimensional earth surface displacement the supersar imaging system a novel multi azimuth synthetic aperture radar sar system capable of detecting earth surface deformation in three dimensions from a single satellite platform has recently been proposed in this paper we investigate the feasibility of detecting precise 3 d surface displacement measurements with the supersar imaging system using a point target simulation from this simulation we establish both a relationship between the interferometric sar phase and the across track displacement and a relationship between the multiple aperture interferometry phase and the along track displacement based on the supersar imaging geometry the theoretical uncertainties of the supersar measurement are analyzed in the across and along track directions and the theoretical accuracy of the 3 d displacement measurement from the supersar system is also investigated according to both the decorrelation and the squint and look angles in the case that the interferometric coherence is about 0 8 and that five effective looks are employed the theoretical 2 d measurement precision values are about 3 67 and 6 35 mm in the across and along track directions respectively and the theoretical 3 d measurement precision values for 3 d displacement are about 4 05 4 56 and 3 45 mm in the east north and up directions respectively the result of this study demonstrates that the supersar imaging system is capable of measuring the 3 d surface displacement in all directions with subcentimeter precision

revised sm nd systematics of kambalda greenstones western australia sm nd isotope systematics in mafic ultramafic lavas from the norseman wiluna greenstone belt western australia have been reinvestigated a previous age based on mixing lavas and granites is not confirmed instead a sm nd age of 3 262 44 myr is indicated for the lavas 400 myr older than intruding granites and predating gneisses that have been proposed as basement rocks

structural setting and geochemistry of archaean i type granites in the bardoc coolgardie area of the norseman wiluna belt western australia abstract regional structures in the bardoc coolgardie area of the archaean norseman wiluna greenstone belt in western australia developed during early large scale thrusting followed by a transpressional regime characterized by enewsw shortening and large scale sinistral strike slip faults structural relationships between granites and greenstone successions indicate emplacement of granitic rocks throughout this deformation history emplacement mechanisms include solid or liquid state diapirism forceful dilation of country rocks and passive stoping i type granites are common and include early and late tectonic intrusions the widespread occurrence of i type granodiorite and monzogranite probably derived by partial melting of lower continental crust or subducted oceanic crust suggests a continental margin setting for the belt alkalic quartz diorite occurs as rounded enclaves in granodiorite and is enriched in ba rb sr ce la p and f which suggests a mantle derived volatile component these quartz diorite melts may have formed by partial melting of metasomatized mantle or alternatively mantle degassing may have lowered solidus temperatures in the source region and thus induced melting emplacement of hot volatilerich quartz diorite melts into the lower crust may have lowered solidus temperatures in the source rocks for granodiorite and monzogranite recent models for archaean gold mineralization suggest that auriferous fluids contained co 2 derived from lower crustal or mantle sources in the bardoc coolgardie area co 2 may have been flushed out during partial melting of the lower continental crust however the origin of the gold in the mineralizing fluids requires some other explanation because gold mineralization is generally a late stage event and took place over a considerably shorter time interval than the formation and emplacement of i type granites

coseismic three dimensional displacements determined using sar data theory and an application test we present a methodology to construct three dimensional deformation maps using different parameters that can be extracted using sar data we apply the methodology using envisat sar data before and after the december 26 th 2003 mw 6 6 bam earthquake in iran to determine spatial quasi continuous three dimensional coseismic deformation maps two near vertical deformation offset components are computed using envisat asar differential interferometry dinsar while two horizontal deformation offset components are measured using sub pixel correlation techniques applied to asar amplitude images using the presented methodology we combine four unevenly precise independent projections of surface coseismic deformation to obtain the full three dimensional coseismic deformation field caused by an earthquake the full 3 d coseismic displacement vector is modeled using elastic deformation models constraining details of the fault geometry and slip distribution at depth results from the inversion are interpreted in the framework of the iranian present day tectonism full exploitation of dense 3 d coseismic surface deformation using sar data even for moderate earthquakes should facilitate distinguishing between different interpretations of the mechanical properties of seismically active areas and within the inherent ambiguity of the geophysical inversion solutions

an early thrust duplex in the kalgoorlie kambalda greenstone belt eastern goldfields province western australia abstract extensive regional mapping of the stratigraphic sequence throughout the kalgoorlie kambalda greenstone belt in western australia has outlined the geometry of early subhorizontal thrust faults these thrusts stacked and repeated the stratigraphy to form a major thrust duplex south of kambalda the roof thrust to the duplex becomes a major thrust flat to the north at kalgoorlie later transpressional deformation f2 upright folds d3 sinistral shear zones and folding has rotated and displaced the d1 thrusts both sub horizontal deformation and subsequent transpression indicate that compressional tectonics rather than vertical tectonics involving solid state granitoid diapirs were crucial in the development of this granite greenstone terrain

emplacement and metamorphism of archaean mafic volcanics at kambalda western australia geochemical and isotopic constraints abstract extensive exploration and mining at kambalda western australia has revealed a conformable mafic ultramafic succession consisting of a sulphide ore bearing ultramafic layer located between metabasalt units geochemical and rb sr u pb isotopic analyses have been carried out on two 70 140 m sections of drill core from the metabasalts and u pb isotopic analyses have been made on sulphide ore samples greenschist metamorphism of the metabasalts is dated at 2610 30 m y and was approximately isochemical except for addition of h 2 o and co 2 and a differential mobilization of k and rb within the units the addition of h 2 o and co 2 is believed to have taken place shortly after extrusion of the metabasalts in a submarine environment resulting in an early greenschist metamorphism the later 2600 m y event is correlated with a high thermal regime also detected at kalgoorlie 50 km to the north a pb pb isochron age of 2720 105 m y may represent the metamorphic event or the time of emplacement of the metabasalts new sm nd data c hauvel et al c laque l ong et al suggest the mafic volcanics are 3200 m y old if true large scale homogenization of pb isotopes is required alternatively the mafic sequence may be only slightly older than 2800 m y and the sm nd data does not have time significance

correcting atmospheric effects on insar with meris water vapour data and elevation dependent interpolation model summary the propagation delay when radar signals travel from the troposphere has been one of the major limitations for the applications of high precision repeat pass interferometric synthetic aperture radar insar in this paper we first present an elevation dependent atmospheric correction model for advanced synthetic aperture radar asar the instrument aboard the envisat satellite interferograms with medium resolution imaging spectrometer meris integrated water vapour iwv data then using four asar interferometric pairs over southern california as examples we conduct the atmospheric correction experiments with cloud free meris iwv data the results show that after the correction the rms differences between insar and gps have reduced by 69 6 per cent 29 per cent 31 8 per cent and 23 3 per cent respectively for the four selected interferograms with an average improvement of 38 4 per cent most importantly after the correction six distinct deformation areas have been identified that is long beach santa ana basin pomona ontario san bernardino and elsinore basin with the deformation velocities along the radar line of sight los direction ranging from 20 mm yr 1 to 30 mm yr 1 and on average around 25 mm yr 1 and santa fe springs and wilmington with a slightly low deformation rate of about 10 mm yr 1 along los finally through the method of stacking we generate a mean deformation velocity map of los angeles over a period of 5 yr the deformation is quite consistent with the historical deformation of the area thus using the cloud free meris iwv data correcting synchronized asar interferograms can significantly reduce the atmospheric effects in the interferograms and further better capture the ground deformation and other geophysical signals

sedimentology of cold climate aeolian sandsheet deposits in the askja region of northeast iceland active aeolian sandsheets cover an area of 270 km2 in the askja region of ne iceland the sandsheet is divided into i a deflationary upwind part that is characterised by deflation lags ventifacted boulder fields and restricted aeolian sand patches in the lee of obstacles ii an accumulating central part that is characterised by continuous aeolian sand cover up to 10 m thick where three scales of aeolian ripples are evident along with larger scale forms including longitudinal zibars and iii a downwind part that is currently subject to aeolian bypass with only localised accumulation occurring in topographic hollows between basaltic lava fields trains of aeolian granule megaripples are a characteristic landform of the downwind part of the sandsheet these sinuous crested oblique bedforms attain heights of 0 35 m and downwind spacings of 6 m they are composed principally of low density pebble grade pumice clasts and other reworked volcaniclastic detritus derived from the nearby askja volcanic centre the distribution of landforms across the sandsheet reflects a regional aeolian sediment budget that is controlled by dynamic interactions between glacial ice margin fluvial aeolian and volcaniclastic processes under the influence of a distinctive climatic regime sediment supply at the upwind sandsheet margin adjacent to the dyngjujokull glacier increases during summer periods when rates of glacial ablation are at a maximum longer term controls on sediment supply rate are determined by episodes of glacier surging and retreat and by periodic eruptions of volcaniclastic debris from the askja volcanic centre the availability of sediment for aeolian transport is controlled by the level of the groundwater table the depth and continuity of the permafrost layer in the proglacial area the degree of development of armoured pebble lags and freezing of the sandsheet surface during winter months the transport capacity of the wind varies on a seasonal basis with mean wind velocities and wind gustiness reaching a maximum during winter periods both winter and summer mean wind velocities have been steadily increasing since formal records began in 1969 the suite of aeolian landforms developed within the askja region as defined by sediment texture and composition and bedform scale morphology and spatial distribution reflects a special set of controlling circumstances which mean that the askja sandsheet deposits differ significantly from those described from elsewhere

interferometric synthetic aperture radar insar atmospheric correction gps moderate resolution imaging spectroradiometer modis and insar integration atmospheric effects represent one of the major limitations of repeat pass interferometric synthetic aperture radar insar in this paper gps and moderate resolution imaging spectroradiometer modis data were integrated to provide regional water vapor fields with a spatial resolution of 1 km 1 km and a water vapor correction model based on the resultant water vapor fields was successfully incorporated into the jet propulsion laboratory california institute of technology roi pac software the advantage of this integration approach is that only one continuous gps station is required within a 2030 km 1354 km modis scene application to ers 2 repeat pass data over the los angeles southern california integrated gps network scign area shows that this integration approach not only helps discriminate geophysical signals from atmospheric artifacts but also reduces water vapor effects significantly which is of great interest to a wide community of geophysicists

major bounding surfaces in aeolian sandstones a climatic model large areas of fixed vegetated dunes occur in the sahel and southern margin of the sahara these dunes were active during late pleistocene times and have been stabilized as a result of a change to more humid less windy conditions in the holocene the stabilized surfaces which are in part of erosional origin are of regional extent within aeolian sand sequences such surfaces form the highest order bounding surfaces since regional bounding surfaces of this type occur in all the world s major deserts it is suggested that they should also be present in some ancient aeolian sandstone sequences

estimating spatiotemporal ground deformation with improved persistent scatterer radar interferometry ast synthetic aperture radar interferometry has been applied widely in recent years to ground deformation monitoring although difficulties are often encountered when applying the technology among which the spatial and temporal decorrelation and atmospheric artifacts are the most prominent the persistent scatterer interferometric synthetic aperture radar ps insar technique has overcome some of the difficulties by focusing only on the temporally coherent radar targets in a time series of synthetic aperture radar sar images this paper presents an improved ps insar technique by introducing ps neighborhood networking and empirical mode decomposition emd approaches in the ps insar solution linear deformation rates and topographic errors are estimated based on a least squares method while the nonlinear deformation and atmospheric signals are computed by singular value decomposition and the emd method an area in phoenix az is used as a test site to determine its historical subsidence with 39 c band sar images acquired by european remote sensing 1 and 2 satellites from 1992 to 2000

archean plate tectonics constraints and inferences the earth has been cooling since archean time the higher temperatures beneath archean ridges resulted in more partial melting which extended down to greater depths than at present the archean oceanic crust was much thicker 20 km than modern crust 5 km this inference is compatible with previous ideas of suspected oceanic crust the thicker oceanic crust in the archean tended to resist subduction similar to modern aseismic ridges but could not prevent it short lived episodes of intra arc spreading followed by cordilleran type compression may have produced archean greenstone belts archean meta tonalites represent a significant part of the continental crust and were probably produced by melting of the subducted slab which was favored by the higher mantle temperatures

structural geology across a proposed archaean terrane boundary in the eastern yilgarn craton western australia abstract the eastern goldfields province of the archaean yilgarn craton western australia can be divided into several nw se trending terranes with different stratigraphic signature at least two main phases of penetrative ductile deformation affect the terranes d1 is a phase of nappe type transport mainly to the north along gently dipping ductile shear zones it is interpreted as a phase of regional extension contemporaneous with intrusion of massive granitoid plutons and possibly contemporaneous with deposition of felsic volcanics and metasediments in the greenstone belts terrane boundaries were probably formed during d1 d2 gave rise to steep nw se to n s trending foliations and upright folds d2 is strongly partitioned over the area for strain and vorticity the pattern of partitioning seems to be dependent on the position of granitoid plutons which give rise to development of d2 strain shadows d1 structures have been preserved mainly in these strain shadows terrane boundaries are transected by boundaries of d2 structural domains minor intrusion of granitoids continued during and after d2 d1 is possibly associated with arrival of a mantle plume below the yilgarn craton and d2 may be a phase of regional shortening in a thinned lithosphere weakened by the thermal event

the nature and dimensions of regional and local gold related hydrothermal alteration in tholeiitic metabasalts in the norseman goldfields the missing link in a crustal continuum of gold deposits the archaean lode gold deposits at norseman western australia consist of auriferous quartz veins in dextral reverse ductile brittle shear zones within tholeiitic metabasalts of upper greenschist to amphibolite facies metamorphic grade three types of deposits northern central southern are delineated on the basis of their spatial distribution veining style alteration mineraloty and metamorphic grade of host rocks northern deposits hosted in upper greenschist to lower amphibolite facies rocks comprise massive to laminated quartz veins with selvedges of quartz chlorite calcite biotite plagioclase assemblages central deposits hosted in lower amphibolite facies rocks consist of laminated to massive quartz veins with selvedges of quartz actinolite biotite plagioclasecalcite assemblages southern deposits hosted in middleamphibolite facies metabasalts consist of banded quartz diopside calcite microcline zoisite veins all deposits exhibit variable ductile deformation of veins and contiguous alteration haloes consistent with a syn deformational genesis at high temperatures from northern to southern deposits the alteration assemblages are indicative of higher temperatures of formation and there are progressively greater degrees of dynamically recovered textures in alteration and gangue minerals these observations imply that a thermal variation of gold related hydrothermal alteration exists within the norseman terrane over a distance of 40 km with tnorthern tcentral tsouthern this thermal zonation is corroborated by t xco 2 phase relations between vein selvedge assemblages which signify formation temperatures of approximately 420 475 c 470 495 c and 500 c for northern central and southern deposits respectively the sum of structural petrographic and mineral chemistry data indicates that the alteration assemblages formed in high temperature open hydrothermal systems and have not been subsequently metamorphosed the thermal differences between the deposit groups may reflect 1 a temperature gradient at relatively constant p corresponding to the proximity of the deposits to regional granitoid complexes or 2 formation of the deposits at progressively deeper crustal levels from north to south in either case the deposits represent a continuum of gold deposition from upper greenschist to amphibolite facies now exposed in an oblique section through the archaean crust at norseman

fluvial aeolian interactions part i modern systems two modern fluvial aeolian depositional systems great sand dunes national monument colorado and the mojave river wash california are remarkably similar in spite of different climates sizes fluvial sediment textures and relative directions of aeolian and fluvial transport dune growth and migration and deflation of blowouts create 8 10 m of local relief in unflooded aeolian landscapes there are six prominent fluvial aeolian interactions 1 fluvial flow extends into the aeolian system until it is dammed by aeolian landforms 2 interdune areas overbank interdunes upstream of aeolian dams and alongside channels are flooded 3 water erodes dunes alongside channels and interdunes 4 flood waters deposit sediment in interdune areas 5 fluvially derived groundwater floods interdunes interdune playas 6 wind erodes fluvial sediment and redeposits it in the aeolian system unique and characteristic sediments are deposited in overbank interdunes and in interdune playas reflecting alternate fluvial and aeolian processes and rapidly changing flow and salinity conditions these fluvial aeolian interdune deposits are characterized by irregular concave up bases and flat upper surfaces containing mudcracks or evaporite cement characteristic low relief surfaces form in aeolian systems as an effect of flooding fluvial deposits are resistant to aeolian deflation aeolian sand is preserved when flood sediments are deposited around the bases of the dunes thus repetitive fluvial and aeolian aggradation tends to be stepwise as interdune floors are suddenly raised during floods the effects of flooding should be easy to recognize in ancient aeolianites even beyond the area covered with overbank muds

tectonic contraction across los angeles after removal of groundwater pumping effects after the 1987 whittier narrows and 1994 northridge earthquakes revealed that blind thrust faults represent a significant threat to metropolitan los angeles a network of 250 continuously recording global positioning system gps stations was deployed to monitor displacements associated with deep slip on both blind and surface faults here we augment this gps data with interferometric synthetic aperture radar imagery to take into account the deformation associated with groundwater pumping and strike slip faulting after removing these non tectonic signals we are left with 4 4 mm yr 1 of uniaxial contraction across the los angeles basin oriented n 36 degrees e perpendicular to the major strike slip faults in the area this indicates that the contraction is primarily accommodated on thrust faults rather than on the northeast trending strike slip faults we have found that widespread groundwater and oil pumping obscures and in some cases mimics the tectonic signals expected from the blind thrust faults in the 40 km long santa ana basin groundwater withdrawal and re injection produces 12 mm yr 1 of long term subsidence accompanied by an unprecedented seasonal oscillation of 55 mm in the vertical direction and 7 mm horizontally

neoarchaean metamorphic evolution of the yilgarn craton a record of subduction accretion extension and lithospheric delamination abstract the greater part of the metamorphic record of the yilgarn craton formed during a protracted middle neoarchaean orogenic cycle spanning from about 2750 to 2620 ma at least six distinct metamorphic events are defined by parageneses in different tectono stratigraphic settings this review characterizes the middle neoarchaean metamorphic response of the entire craton using large databases rock descriptions from 60 000 sites in government databases and 1040 pt determinations from all sources are used to construct metamorphic map patterns for each of these metamorphic events p t paths and timing of each metamorphic event are characterized using petrology and the well constrained pt determinations from this study n 287 combined with metamorphic age determinations from all sources n 114 the spatial patterns and metamorphic conditions of each event provides critical constraints on tectonic settings and changes in tectonics over 130 million years the record of metamorphism in conjunction with stratigraphic kinematic and magmatic constraints shows that the neoarchaean craton evolved from an accretionary crustal growth phase ma and m1 to thermal reworking of the crust during massive influx of granitic intrusions m2 and lithospheric extension after the termination of subduction m3 these events were followed by lithospheric delamination resulting in a craton wide diffusion delayed thermal pulse that coincided with renewed contraction m4 m1 metamorphism at 2748 19 2727 8 and 2706 10 ma experienced high p moderate t hairpin clockwise p t paths during burial of magmatic arc margins during terrane accretion events m2 regional contact type metamorphism at 2671 6 ma tracked low p moderate t clockwise p t paths in back arc settings during voluminous felsic magmatism related to shallow subduction m3 metamorphism at 2656 5 ma experienced low p moderate t anticlockwise p t paths in post volcanic rift basins formed during lithospheric extension m4 metamorphic peaks at 2644 4 and 2629 7 ma experienced low p high t clockwise p t paths during regional scale thermal pulses resulting from lower crust and mantle lithosphere delamination at 2665 2668 ma

gliding and overthrust nappe tectonics in the barberton greenstone belt abstract regional recumbent folds inverted stratigraphy nappes and olistostromes are described from the southern part of the 3 3 3 5 ga barberton greenstone belt overthrusting of thin rigid silicified slabs with minimum dimensions of 25 km2 and up to 500 m in thickness occurred over minimum distances of 86 km more ductile and coherent units were overfolded up to at least 2 km during their emplacement the glide planes on which these nappes travelled were zones of high fluid pressures related to hydrothermal fluid circulation patterns driven by heat sources from igneous intrusions the upwelling areas of the geothermal convection cells were sites of mud pools and hydrothermal vents which may mark the trailing edges pull aparts of the overthrust units progressive silica and carbonate precipitation due to decreasing temperatures within the zones of fluid migration distant from the areas of high heat flow probably acted as built in braking systems below the travelling slabs active sedimentation and metasomatism during this tectonism indicates a protracted history for the evolution of the greenstone belt the recognition of nappe and overthrust tectonics in the barberton belt processes which may have been commonplace in archaean terrains necessitates a re evaluation of the stratigraphy of this belt

application of dinsar gps optimization for derivation of fine scale surface motion maps of southern california a method based on random field theory and gibbs markov random fields equivalency within bayesian statistical framework is used to derive 3 d surface motion maps from sparse global positioning system gps measurements and differential interferometric synthetic aperture radar dinsar interferogram in the southern california region the minimization of the gibbs energy function is performed analytically which is possible in the case when neighboring pixels are considered independent the problem is well posed and the solution is unique and stable and not biased by the continuity condition the technique produces a 3 d field containing estimates of surface motion on the spatial scale of the dinsar image over a given time period complete with error estimates significant improvement in the accuracy of the vertical component and moderate improvement in the accuracy of the horizontal components of velocity are achieved in comparison with the gps data alone the method can be expanded to account for other available data sets such as additional interferograms lidar or leveling data in order to achieve even higher accuracy

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

coseismic and postseismic deformation estimation of the 2011 tohoku earthquake in kanto region japan using insar time series analysis and gps abstract we propose a methodology using interferometric synthetic aperture radar insar time series analysis and a single gps station to estimate the coseismic and postseismic crustal deformations in the kanto region japan which has been affected by the 2011 tohoku earthquake the proposed methodology depends on choosing a proper deformation trend s to accurately describe the earthquake deformation signature by studying the deformation time series of a single gps station the modeled deformation trend is subtracted from the unwrapped phase maps to separate the main deformation signature from the imposed errors some deformation components not described by the model s will leak to the residual phase maps which will be subjected to temporal and spatial filtering the final corrected unwrapped phase maps are estimated by restoring the modeled deformation trend to the filtered residual phase maps and finally the deformation time series is estimated using a least squares technique the proposed methodology was designed to retrieve complex and fine surface deformations in areas that have been affected by large dominating deformation signatures and contain at a least single gps station the methodology was tested using envisat asar c band images and validation was carried out using gps stations resulting in a mean rms error of 6 9 mm the estimated deformation time series shows a differential postseismic deformation pattern that can be attributed to an off boso peninsula motion triggered by the 2011 tohoku earthquake

landsat mss imagery applied to geological investigation of the norseman area granitoid greenstone terrain southeast yilgarn block western australia interactively processed landsat mss imagery has been used as an aid to studying the regional geology of approximately 10 800 km 2 of terrain at the southeast margin of the archaean yilgarn block in western australia the technique proved successful in extending positions of known lithological contacts and lineaments into poorly exposed inaccessible areas and in revealing new geological features especially faults previously unrecognized at ground level during this investigation the distribution of granitoids and greenstones was more precisely defined internal greenstone structures highlighted and three main fault trends were identified 1 nw nnw and 2 ene both within archaean shield and 3 ne nne within the transition to adjacent proterozoic mobile belt in order for the most information to be extracted from landsat mss images it is recommended that whenever possible image processing should follow ground based studies as well as precede them and that field geologist and landsat specialist should work at the image processing system together

an elliptical model for deformation due to groundwater fluctuations historically surface subsidence as a result of subsurface groundwater fluctuations have produced important and at times catastrophic effects whether natural or anthropogenic over the past 30 years numerical and analytical techniques for the modeling of this surface deformation based upon elastic and poroelastic theory have been remarkably successful in predicting the magnitude of that deformation le mouelic and adragna in geophys res lett 29 1853 2002 in this work we have extended the formula for a circular shaped aquifer geertsma in j petroleum tech 25 734 744 1973 to a more realistic elliptical shape we have improved the accuracy of the approximation by making use of the cross terms of the expansion for the elliptic coordinates in terms of the eccentricity e and the mean anomaly angle m widely used in astronomy results of a number of simulations in terms of e and m developed from the transcendental kepler equation are encouraging giving realistic values for the elliptical approximation of the vertical deformation due to groundwater change finally we have applied the algorithm to modeling of groundwater in southern california

dynamothermal transition zone between archaean greenstone and granitoid gneiss at lake dundas western australia abstract a 500 m wide shear zone occurs between the base of an archaean greenstone sequence and adjacent granitoid gneiss complex on the shores of lake dundas western australia the dynamothermal margin remains distinguishable due to the preservation of upper amphibolite facies assemblages related granitoid anatectites and mylonitic schistose and gneissose fabrics developed parallel to the contact which itself lies subparallel to the greenstone bedding surface the margin contrasts with less deformed greenschist to low amphibolite facies assemblages which characterize lithologies within the greenstone belt many of which retain igneous textures and relict primary phases structural petrological and textural evidence indicates that the dynamothermal contact originally evolved as a subhorizontal ductile shear zone during juxtaposition of the greenstone pile with granitoid gneiss and that its formation preceded regional folding greenschist facies overprinting and granitoid intrusion which occurred at about 2700 ma the amount of heat generated within the transition zone during thrusting was limited to maximum temperatures of c 650 c due to the buffering effect of granitoid anatexis

the stabilizing role of bonding agents on the entrainment of sediment by wind well sorted fine sand pretreated with varying concentrations of two soluble salts mgcl2 and cacl2 was tested for threshold shear velocity in a recirculating wind tunnel these tests demonstrate that even relatively low surface salt concentrations can significantly increase threshold shear velocity however the relationships between surface salt concentration and threshold shear velocity for the two salts were not significantly different which is similar to the results for monovalent chlorides presented by nickling ecclestone a general relationship between threshold shear velocity and total surface soluble salt content is presented

satellite interferometry for mapping surface deformation time series in one two and three dimensions a new method illustrated on a slow moving landslide abstract space borne differential interferometric synthetic aperture radar dinsar has been extensively used in the last two decades to measure ground surface deformation providing key information for the characterization and understanding of many natural and anthropogenic processes however conventional dinsar technique measures only one component of the surface deformation i e the satellite s line of sight los causing the interpretation of dinsar measurements to be challenging and potentially narrowing the understanding of the mechanisms and dynamics of the deformation processes at work presently available methods that estimate 3d surface deformation from dinsar generally operate on individual interferograms and therefore do not produce 3d surface deformation time series however the availability of time series is essential for studying surface deformation processes bringing information on e g temporally and spatially variable external forcing conditions and characteristics of future deformation patterns the multidimensional small baseline subset msbas method was already able to produce 2d east and vertical surface deformation time series from multi tracks and multi sensors dinsar data here we propose a novel version of the msbas msbas 3d method that can produce 3d north east and vertical surface deformation time series from ascending and descending dinsar data this new method proposes measuring the surface deformation for processes producing motion parallel to the surface such as landslides and glacier flows while conserving the dinsar accuracy the ability of msbas 3d to capture the full 3d deformation pattern of processes with a surface signature is illustrated for a large slow moving deep seated landslide for which long dinsar and dgnss time series as well as ground truth data are available surface deformation is measured over a four year period using 1d los 2d and 3d msbas methods and the advantages and limitations of each approach are described in this case the novel msbas 3d technique produces superior results that greatly simplify interpretation of the processes at work the msbas 3d software can be downloaded from http insar ca

character and regional implications of the sheared archaean granite greenstone contact near leonora western australia abstract the boundary between greenstone belt rocks and deformed domal bodies of granite and gneissic granite in the area west and northwest of leonora is marked by a wide zone of high strain within which the dominant fabric elements are parallel to the boundary the high strain zone is arcuate the granitic body is domal in form consistent sense of shear movement indicators show that the greenstones moved down relative to the granite rocks from a continuous core of 1 6 km drilled 4 km southeast of leonora exhibit mesoscale recumbent folding and ductile faulting the upper 900 m of core is characterised by recumbent flexural slip folds with half wavelengths up to 660 m separated by discrete shear zones below about 1200 m rock type and structural character change at this depth greenschistfacies rocks are juxtaposed against amphibolite facies rocks across a major ductile shear thermodynamic data give estimates of 370 c 2 1 kbar for greenschist and 610 c 5 6 kbar for amphibolite facies with high fluid pressures dominated by water in low grade rocks and co 2 in high grade ones several kilometres of section have therefore been lost across this zone the amphibolite hosts broad and narrow shear zones within which movement sense is consistently normal the structural and metamorphic data suggest that emplacement of the domal granitic and gneissic rocks was temporally linked with normal ductile shearing the regional structural setting and juxtaposition of high and low grade rocks across the shear zone with abrupt changes in temperature and fluid composition suggests that the domes were emplaced as uprising hot deep seated rock in a regional extensional tectonic environment comparable to the tectonic setting of metamorphic core complexes

3d displacement maps of the 2009 l aquila earthquake italy by applying the sistem method to gps and dinsar data terra nova 25 79 85 2013 abstract we present an application of the novel sistem approach to obtain the dense 3d ground deformation pattern produced by the april 6 2009 mw 6 3 l aquila earthquake this event characterized by a sw dipping normal fault with thousands of foreshocks and aftershocks located in the depth range 5 15 km is the most destructive to have struck the abruzzo region since the major 1703 seismic sequence the surface deformation revealed by the sistem through the integration of gps with interferometric measurements from the envisat and alos satellites shows a deformed area extending towards se along the aterno valley in agreement with seismological and other geodetic observations we inverted the sistem results using an optimization algorithm based on the genetic algorithm providing an accurate spatial characterization of ground deformation our results improve previous kinematic solutions for the paganica fault and allow identification of additional faults that have contributed to the observed complex ground deformation pattern

three dimensional surface motion maps estimated from combined interferometric synthetic aperture radar and gps data 1 we provide a technique to efficiently produce high resolution three dimensional surface motion maps by combining information about the motion of the earth s surface from interferometric observations of synthetic aperture radar images and repeated global positioning system gps geodetic measurements unwrapped interferograms showing pixel wise change in range from ground to satellite and sparse values of threedimensional movements are required as input the problem of finding the full threedimensional motion field is separated into two two dimensional problems initially the vertical component of the deformation field and its horizontal component in the look direction of the satellite are found later the look direction component is resolved into north and east components initial values for the motion fields are assigned to each pixel of interferograms from interpolation of available gps observations these values are then updated and optimized by comparison with the interferograms and the gps observations an additional constraint is an assumption of a smoothly varying motion field markov random field based regularization and simulated annealing algorithm are used for the optimization the technique is applied to create surface motion maps for the reykjanes peninsula sw iceland index terms 0933 exploration geophysics remote sensing 0910 exploration geophysics data processing 1206 geodesy and gravity crustal movements interplate 8155 8150 tectonophysics evolution of the earth plate boundary general 3040 8155 tectonophysics evolution of the earth plate motions general keywords remote sensing motion maps deformation data fusion interferometry gps

satellite interferometric observations of displacements associated with seasonal groundwater in the los angeles basin 1 the newport inglewood fault zone nifz displays interferometric synthetic aperture radar sar phase features along most of its length having amplitudes of up to 60 mm however interpretation in terms of right lateral shallow slip along the fault fails to match the range of geologic estimates of slip recently bawden et al 2001 proposed that these phase features as well as a broader deformation pattern in the los angeles basin are due to vertical motion related to annual variations in the elevation of the water table we confirm this hypothesis through the analysis of a longer span of data consisting of 26 sar images collected by the ers 1 and ers 2 spacecraft between june 1992 and june 2000 moreover we use continuous gps measurements from 1995 to the present to establish the amplitude and phase of the vertical deformation the los angeles basin becomes most inflated one quarter of the way through the year which is consistent with water table measurements as well as with the end of the rainy season when the aquifer should be at a maximum the spatial pattern of the amplitude of the annual signal derived from continuous gps measurements is consistent with the shape of the interferometric fringes gps sites both near the nifz and in a 20 by 40 km zone within the basin also show significant n s annual variations that may be related to the differential expansion across the fault since these horizontal signals have peak to trough amplitudes of 6 mm they mask the smaller tectonic signals and need to be taken into account when interpreting gps time series of site position moreover since the groundwater signal appears to have a long term vertical trend which varies in sign depending on location it will be difficult to distinguish interseismic tectonic slip along the nifz and within the affected areas in the basin

stratigraphic evolution of a fluvial eolian succession the example of the upper jurassic lower cretaceous guara and botucatu formations parana basin southernmost brazil abstract the guara and botucatu formations comprise an 80 to 120 m thick continental succession that crops out on the western portion of the rio grande do sul state southernmost brazil the guara formation upper jurassic displays a well defined facies shift along its outcrop belt on its northern portion it is characterised by coarse grained to conglomeratic sandstones with trough and planar cross bedding as well as low angle lamination which are interpreted to represent braided river deposits southwards these fluvial facies thin out and interfinger with fine to medium grained sandstones with large scale cross stratification and horizontal lamination interpreted as eolian dune and eolian sand sheets deposits respectively the botucatu formation is characterised by large scale cross strata formed by successive climbing of eolian dunes without interdune and or fluvial accumulation dry eolian system the contact between the guara and the botucatu formations is delineated by a basin wide deflation surface supersurface the abrupt change in the depositional conditions that took place across this supersurface suggests a major climate change from semi arid upper jurassic to hyper arid lower cretaceous conditions a rearrangement of the parana basin depocenters is contemporaneous to this climate change which seems to have changed from a more restrict accumulation area in the guara formation to a wider sedimentary context in the botucatu formation

climate induced sediment palaeosol cycles in a late cretaceous dry aeolian sand sheet marilia formation north west bauru basin brazil aeolian sand sheets which are characterized by low relief surfaces that lack dunes are common in arid and semi arid climatic settings the surface of an aeolian sand sheet can either be stable and subject to pedogenetic effects or unstable such that it is affected by deflation or sedimentation the maro lia formation late cretaceous may be interpreted as an ancient aeolian sand sheet area where alternating phases of stability and instability of the accumulation surface have been recorded detailed field studies were carried out in several sections of the maro lia formation where cyclic alternations of palaeosols and aeolian deposits were evident using palaeopedological and facies analysis methods supported in the laboratory by the analysis of rock samples cut and polished in slabs thin sections scanning electron microscope images and x ray diffraction data from the clay minerals the deposits comprise three lithofacies that in order of abundance are characterized by i translatent wind ripple strata ii flood deposits and iii ephemeral river channel deposits palaeosols constitute on average 65 of the vertical succession three types of palaeosols pedotypes are recognized i aridisols ii entisols and iii vertisols erosional surfaces due to aeolian deflation divide the top of the palaeosol profiles from the overlying aeolian deposits the palaeoenvironmental interpretation of the deposits and the palaeosols allows the depositional system of the maro lia formation to be defined as a flat area dominated by aeolian sedimentation with subordinate ephemeral river sedimentation and characterized by a dry climatic setting with occasional rainfall the climate is the main forcing factor controlling the alternation between episodes of active sedimentation and periods of palaeosol development a climate controlled model is proposed in which i the palaeosols are indicative of a stable surface that is developed during the more humid climatic phases and ii the erosional surfaces and the overlying aeolian sediments attest to periods of deflation and subsequent sedimentation thereby increasing the availability of sediment during the drier climatic phases the ephemeral fluvial deposits mark the more humid climatic conditions and contribute to the lagged sediment influx caused during the drier periods by the erosion of previously stored sediment

derivation of 3 d coseismic surface displacement fields for the 2011 mw 9 0 tohoku oki earthquake from insar and gps measurements

sedimentary cycles and facies architecture of aeolian fluvial strata of the upper jurassic guara formation southern brazil the upper jurassic guara formation comprises an 80 200 m thick continental succession exposed in the western portion of the rio grande do sul state brazil it comprises four distinct facies associations i simple to locally composite crescentic aeolian dune sets ii aeolian sand sheets iii distal floodflows and iv fluvial channels the vertical stacking of the facies associations defines several 5 14 m thick wetting upward cycles each cycle starts with aeolian dune sets followed by aeolian sand sheets deposits and culminating in either fluvial channels or distal flood strata within some cycles aeolian sand sheets are absent and fluvial deposits rest directly above aeolian dune facies the transitions from one facies association to another are abrupt and marked by erosive surfaces that delineate distinct episodes of sediment accumulation the origin of both the wetting upward cycles and the erosive surfaces was controlled by the ground water table level dry sand availability and aeolian and fluvial sediment transport capacity variations related to climatic fluctuations between relatively arid and humid conditions preservation of the fluvial aeolian deposits reflects an overall relative water table rise driven by subsidence

evidence for structural repetition in the greenstones of the kalgoorlie district western australia abstract regional mapping and air photographic interpretation of an area of about 20 000 km 2 centred on kalgoorlie provided compelling evidence that some previously published polycyclic stratigraphies cannot be substantiated large areas of rocks formerly proposed as younger cycles represent repetition mainly by faulting of a somewhat simpler stratigraphic sequence the main lines of support are 1 the similarity of older and younger mafic ultramafic successions 2 the tendency of younger sequences to merge with older ones when traced along strike and 3 the abundant evidence of faulting along critical contacts the subtle concordant nature of some of the faulting is consistent with an origin by thrusting at an early stage in the tectonic history especially where repeat sequences are folded around major upright structures later reactivation of sheared contacts and initiation of new ones during upright folding and faulting and transcurrent shearing is believed to have widely occurred gravitational gliding is proposed as a possible mechanism for thrust generation this being consistent with evidence of earlier instability in the sedimentation style of turbidites debris flows and olistostromes however conclusive evidence of a mechanism is lacking due to incomplete field evidence the repetition is viewed as a rearrangement of recognisable elements of the local stratigraphy rather than the result of a major collisional event at a plate margin this tends to favour an intracratonic rather than an oceanic setting for the local greenstones though the characteristic geological features of modern continental rifts have not been observed

proterozoic crustal extension and the generation of dome and keel structure in an archaean granite greenstone terrane archaean granite greenstone terranes1 3 in which narrow belts of greenstone ultramafic and mafic volcanics and overlying sedimentary rocks occur in association with broad provinces of granite granitic igneous rocks gneiss and migmatite have long puzzled geologists because of the lack of any clear modern analogues not only is there uncertainty about how the greenstone formed in the first place4 6 but there is continuing debate about how and when the terranes developed their distinctive structural and metamorphic architecture many granite greenstone terranes display a dome and keel geometry in which belts of supracrustal volcanic and sedimentary rocks occur as structural troughs wedged between dome shaped bodies of the granite gneiss migmatite complex a metamorphic aureole typically occurs in the supracrustals adjacent to their contact with the domes and the contact itself is a shear zone here we report the results of field studies of a granite greenstone terrane in brazil showing that this architecture originated during the proterozoic more than 500 million years after extrusion of the greenstone we suggest that the thermal regime and deformation kinematics necessary to create this architecture could be generated during an episode of crustal extension when hot basement rocks were transported upwards along a transcrustal normal fault system to the base of the supracrustals

rhizoliths in ancient eolianites abstract rhizoliths are abundant within permo pennsylvanian eolian rocks of southeastern utah they are also present at the tops of several eolian sand bodies within the pennsylvanian fountain formation of southeastern wyoming and at a single stratigraphic level within the jurassic navajo sandstone of southeastern utah ranging in diameter from less than 1 mm to 15 cm these cylindrical structures are composed of siliciclastic free micrite and calcite spar cylinders ramify throughout the uppermost 2 3 m of thin flat topped sand bodies large cylinders are compound rhizoliths and display alveolar fabric a feature resulting from rootlet calcification that is characteristic of modern and ancient calcretes development of rhizoliths required flat geomorphically stable substrates for plant growth highly permeable surficial sediments and sources of calcium ions the restriction of rhizoliths to planar deflation surfaces suggests that plants were unable to colonize or stabilize eolian bedforms paleozoic rhizoliths appear to be restricted to coastal areas with onshore winds associated evaporites suggest an arid to semi arid paleoclimate rhizoliths formed when carbonate allochems derived from an upwind epeiric sea were dissolved and calcite reprecipitated around plant roots quaternary rhizoliths are best developed in similar sedimentologic and geographic settings the abundance of rhizoliths and carbonate allochems in quaternary and late paleozoic low latitude coastal dunes suggests that they are genetically related to glacio eustatic sea level fluctuations

eolian aqueous interactions in the development of a proterozoic sand sheet shikaoda formation hosangabad india abstract a 40 m thick eolian sand sheet deposit characterizes the upper part of the proterozoic shikaoda formation near hosangabad it sharply overlies shoreface deposits and comprises wind ripple strata 50 adhesion strata 17 and subaqueous strata 33 each stratification type defines stratal packages tens of centimeters thick and few meters wide that are superposed upon one another in a nearly random fashion the eolian facies is inferred to have been deposited in a low gradient sandy supratidal setting the subaqueous deposits of the sand sheet also reflect a tide affected westward opening coastal setting with an approximately north south shoreline abundance of aqueous and adhesion strata coupled with the absence of granule rich coarse grained layers corrugated erosion surfaces and evaporites are the typical features of the shikaoda eolian sand sheet these features indicate that in spite of abundant sand supply from the coastal sources and a net aggradational setting repeated flooding and high surface moisture were the principal factors that inhibited dune building processes and favored the growth of a flat bedded eolian sand sheet in the shikaoda sandstone numerous subhorizontal nearly flat bounding surfaces split the sand sheet succession into tabular sediment bodies 50 100 cm thick each of the bounding surfaces can be traced for a few tens of meters and can be correlated to an event of aqueous flooding vertical stacking of tabular sandstone bodies implies that long term sediment aggradation rate in the low lying supratidal region kept pace with that of basin subsidence the sedimentological features of the shikaoda sand sheet facies when compared with known modern and ancient sand sheet deposits suggest that the shikaoda sand sheet developed independent of an erg in a comparatively wet climatic setting the sub humid coastal eolian sedimentary system of padre island texas is probably the closest modern analogue of the shikaoda sand sheet facies

accretion of japanese island arcs and implications for the origin of archean greenstone belts the present day region of arc arc collision between the izu bonin arc and mainland japan honshu arc in the western pacific called the izu collision zone or icz provides a useful kinematic model for the development of many archean greenstone belts the compositional assemblage thermal structure and structural style of the crust in the icz are very similar to those inferred for many archean greenstone belts in both cases thick young and flaky arc crust with a high heat flux is in collision with another crustal block the icz has resulted in the imbrication of very thick slices of crust and associated sediments juxtaposed against older accretionary prisms many archean greenstone belts show similar geological features and we suggest that the incremental imbrication of the crust was a common tectonic style in some archean convergent margins

radarsat 2 d insar for ground displacement in permafrost terrain validation from iqaluit airport baffin island canada abstract the use of differential interferometric synthetic aperture radar d insar is rapidly gaining acceptance as a source of ground displacement information for permafrost regions the accuracy of the information however is still not well established this paper uses a stack of radarsat 2 d insar data to map seasonal ground displacement at the iqaluit airport baffin island canada the accuracy and information content of the d insar products are evaluated with a variety of ground truth data the d insar derived seasonal ground displacement patterns align well with surficial geology units and reflect the thaw settlement characteristics of the sediments they also identify localised displacement patterns in the vicinity of features such as ice wedges and frost cracks comparisons with ground settlement measurements from in situ thaw tubes indicate sub centimetre agreement in dry areas in low lying wet areas however subject to saturation and flooding the d insar stack significantly underestimates the true settlement detecting only 3 7 cm of the 8 5 cm thaw tube measurement the combination of high phase gradients and poor coherence over intermittently flooded surfaces makes it challenging to preserve reliable phase measurements in these areas information from electromagnetic surveys shows that some surface displacement is related to sub surface conditions

analysis of the evolution of ground movements in a low densely urban area by means of dinsar technique abstract this paper presents an application example of the use of the differential interferometry synthetic aperture radar technique dinsar for monitoring ground movements in a geologically complex area around the village of suria ebro basin catalonia ne spain associated to underground mining activities and to the presence of a salt dome the analysis has been mostly performed in a rural environment affected by ground movements with different patterns magnitudes and causes a total of fifty sar images recorded between 1995 and 2007 were processed to generate the interferograms in order to study the non linear trends or changes of the ground surface behavior the dinsar technique was applied in two sets of images the interferometric results in the form of vertical displacement rate maps were checked against conventional surveying and gps measurements the results present a significant discrepancy in some location due to the wrapping of the phase when both fast and significant deformations occur in order to avoid the latter effect and improve the accuracy of the results all sar images were reprocessed using topographic leveling and gps data of different monitored points to support the dinsar interpretation a detailed geological reconnaissance of the study area was carried out as well as an inventory of ground movement indicators four different patterns of ground movement have been identified active shifting subsidence associated to the progression of the mining exploitation fronts residual subsidence on abandoned galleries with a decreasing rate of closure uplifting due to the intrusion of the salt dome and sudden ground collapses sinkholes caused by the dissolution of soluble materials laying close to the ground surface

the geology of the kambalda nickel field western australia the kambalda nickel field contains the major concentration of volcanic peridotitc associated nickel ores in the archean of australia it occupies an area of 400 km 2 underlain by two sequences of ultramafic mafic and felsic volcanics and sedimentary rocks which can be broadly correlated with previously erected regional stratigraphic sections most ores occur in the lower kambalda sequence at the base of the kambalda ultramafic rocks the ultramafic rocks of the upper bluebush sequence contain only minor mineralization four phases of deformation occurred over an interval of more than 300 m y resulting in a dominant north northwest structural trend faulting was active during original volcanism and continued intermittently until after mafic felsic dike intrusion the ultramafic rocks have been serpentinized and all rocks have exerienced low strain upper greenschist to lower amphibolite facies metamorphism and variable carbonation and potash metasomatism the kambalda ultramafic rocks are of variable thickness and in places exceed 1 000 m the lower member of the ultramafic rocks occupying approximately one third of the sequence comprises thicker high magnesium flows i e generally 36 volatile free mgo commonly separated by sulfidic quartz albite sediments thinner lower magnesium flow units characterize much of the upper member the ores occur in 24 shoot complexes each containing multiple ore surfaces caused by structural dislocation of a few grouped ribbonlike original orebodies eighty percent is contact ore occurring at the base of the lowermost ultramafic flow and generally occupying elongate troughs in the footwall basalt ultramafic contact these troughs are thought to be original volcanic depressions which focused later deformation the remainder is hanging wall ore usually occurring directly above contact ore at the base of the second or third ultramafic flow hanging wall orebodies occasionally grade into stratigraphically equivalent interflow sediments the ores contain varying proportions of massive matrix and disseminated sulfides the hypogene mineral assemblage is pyrrhotite pentlandite pyrite chalcopyrite but millerite is locally significant the massive ores in particular are commonly severely deformed and some have been remobilized tens of meters from their original contact position metamorphism has caused recrystallization of the ores and some redistribution of elements there is commonly marked variation of mineralogy and s ni ratios between contact and overlying hanging wall ores and within and between original ore surfaces within shoots but the relative contributions of primary composition and metamorphism to this variation are uncertain in ore environments the footwall basalt ultramafic contact is more deformed than in non ore environments the basal ultramafic flows are thicker and richer in magnesium the trend toward lower magnesium flows upward through the ultramafic formation is less well developed and there is better textural development and compositional differentiation within flows non ore environments usually contain interflow sediments whereas there is generally a sediment free prism of ultramafic rocks above ore environments most ores are interpreted to have originated by either simultaneous or sequential extrusion of sulfide melts and ultramafic lavas rich in olivine phenocrysts along active linear fissures in a basaltic ocean floor volcanic exhalations probably contributed to minor ore in sulfidic sediments

estimation of 3 d surface displacement based on insar and deformation modeling a new approach is presented for mapping 3 d surface displacement caused by subsurface fluid volumetric change based on 1 d interferometric synthetic aperture radar insar line of sight measurements and surface deformation modeling the relationship between surface deformation and source fluid volumetric change is modeled according to elastic half space theory a distinctive advantage of the proposed approach is that it effectively extends the capability of the sun synchronous orbit side looking synthetic aperture radar that has been essentially only able to measure 1 d displacements accurately or at most 2 d displacements when insar measurements from more than one orbit or platform are combined experimental studies are carried out with both simulated and real data sets to test the performance of the method the results have demonstrated that the approach works very well