recognition of 18β h oleanane in several crudes and tertiary upper cretaceous sediments definition of a new maturity parameter abstract ekweozor et al chem geol 27 11 28 and 29 37 first discovered an unknown compound with a gc retention time very close to that of the 18 h olenane peak in oils and tertiary sediments of the nigerian delta this compound was called j several authors wang et al advances in organic geochemistry 1981 pp 108 113 wiley chichester 1983 schoelle et al ibid pp 156 163 reported the occurrence of 18 h oleanane without underlying the presence of j because of their coelution in this study the presence of j has been confirmed in more than 150 rock extracts and 19 oils from different countries and is identified as the 18 h oleanane by comparison to retention time and mass spectrum and by its coelution with an authentic standard apart from tertiary sediments the 18 h and 18 h oleananes have also been found in upper cretaceous sediments which extends the occurrence of these compounds back in age a maturity correlation has been found between the relative concentration of 18 h oleanane and 18 h oleanane in fact an increase in the 18 h 18 h oleanane ratio has been observed with increasing depth in several wells the 18 h 18 h oleanane ratio has been correlated with other classical maturity parameters i e ts tm ro and tmax

early diagenesis of terrigenous triterpenoids and its implications for petroleum geochemistry abstract the distribution of triterpanes in sediments and crude oils is commonly used for oil oil and oil source rock correlation in petroleum geochemistry while isomer ratios of such compounds are applied as maturity parameters the triterpane pattern in terrestrially influenced geological samples is however remarkably less diverse than the triterpenoid skeletons occurring in the extant higher plant biosphere natural observations laboratory experiments and molecular mechanics calculations have revealed that acid catalysed double bond isomerization and skeletal rearrangement reactions of terrigenous triterpenoids during early diagenesis are the key to understanding the triterpane patterns in more matured geological materials examples studied in detail are the double bond isomerization of oleanenes and the subsequent hydrogenation of the products into oleanane and 18 oleanane and the transformation of taraxer 14 ene and lup 20 29 ene into oleanenes although the reactions are likely to be kinetically controlled the main products formed and ultimately preserved are the thermodynamically most stable ones the experimental results and natural observations have significant implications for the use of terrigenous triterpenoid compounds in petroleum geochemistry

a comparison of terrasar x radarsat 2 and alos palsar interferometry for monitoring permafrost environments case study from herschel island canada abstract interferometric synthetic aperture radar insar data sets from terrasar x radarsat 2 and alos palsar are compared for their ability to detect ground movement over the continuous permafrost site of herschel island yukon territory canada all three sensors maintain good coherence within a summer season and can be used to create summer displacement products stacking is advantageous for the terrasar x and radarsat 2 data sets although mottling possibly an interaction of the sar with vegetation or residual tropospheric noise is visible reducing the reliability of the results radarsat 2 and alos palsar provide the most promising results with the ability to form one year interval interferograms palsar can also form two and three year interval interferograms long interval data sets spanning 2007 to 2010 identify a band of movement of 20 to 30 cm year along the north east coast and a region of movement of up to 5 cm year near the northern tip of the island the ability to form long interval displacement products holds the most promise for permafrost monitoring since long term trends are of greater interest for permafrost stability than short term seasonal changes terrasar x data have the disadvantage that year to year interferograms cannot be formed insar is not the ideal monitoring technique for the large thaw slumps of herschel island although general areas of instability can be identified specific slump detection is limited by radar look direction and the large and abrupt slump movement often accompanied by disintegration and collapse of slump sections causes loss of coherence in the insar data thaw slumps may require a different interferometric approach such as slump extent mapping from coherence loss or the installation of corner reflectors and point target techniques the frequent revisit and high spatial resolution of terrasar x provide the best chance of maintaining coherence over thaw slumps in general insar is more successful at identifying broad areas of subtle subsidence in gentle relief areas of terrain instability possibly due to permafrost thaw or ground ice melt and the removal of water volume and prior to significant slumping

evolution of the large scale temperature field in the greenland sea during 1988 89 from tomographic measurements the greenland sea ocean acoustic tomography experiment was conducted during 1988 89 as one component of the international greenland sea project to study deep water formation and the response of the gyre to variations in wind stress and ice cover six acoustic transceivers moored in an array 200 km across transmitted to one another at four hour intervals near the end of february 1989 a sub surface temperature maximum at several hundred meters depth disappeared over a surprisingly large area of the central greenland sea while the water column was modified to about 1000 m depth over much of the gyre the surface remained colder than the deeper water contrary to what might be expected from simple models of convective renewal

global crustal stress pattern based on the world stress map database release 2008 the world stress map wsm project is a global compilation of information on the contemporary crustal stress field from a wide range of stress indicators the wsm database release 2008 contains 21 750 stress data records that are quality ranked using an updated and refined quality ranking scheme almost 17 000 of these data records have a c quality and are considered to record the orientation of maximum horizontal compressional stress sh to within 25 as this is almost a triplication of data records compared with the first wsm database release in 1992 we reinvestigate the spatial wave length of the stress patterns with a statistical analysis on a global 0 5 grid the resulting smoothed global stress map displays both the mean sh orientation that follows from the maximum smoothing radius for which the standard deviation is b25 and a countour map that displays the wave length of the stress pattern this smoothed global map confirms that long wave length stress patterns n2000 km exist for example in north america and ne asia these have been used in earlier analyses to conclude that the global stress pattern is primarily controlled by plate boundary forces that are transmitted into the intraplate region however our analysis reveals that rather short wave length of the stress pattern b200 km are quite frequent too particularly in western europe alaska and the aleutians the southern rocky mountains basin and range province scandinavia caucasus most of the himalayas and indonesia this implies that local stress sources such as density contrasts and active fault systems in some areas have high impact in comparison to plate boundary forces and control the regional stress pattern

magnetic properties and potential field modeling of the peculiar knob metamorphosed iron formation south australia an analog for the source of the intense martian magnetic anomalies an extremely intense 120 a m 1 remanence directed steeply upward this ancient remanence reinforces the local earth s field inclination 63 a simple geological model constrained by drilling and physical property measurements explains both the observed magnetic and gravity anomalies consistent with the poisson theorem koenigsberger ratios qs of 10 and greater as found here are rare in nature we postulate that acquisition of a thermoremanent magnetization trm by the ore during

trans atlantic correlation of the palaeogene volcanic successions in the faeroe islands and east greenland before continental break up in the ne atlantic the faeroe islands and central east greenland were within a distance of 100 120 km chemical and lithological data for complete sections through the 5 km thick piles of contemporaneous palaeogene flood basalts in the faeroe islands and in the nansen fjord area in east greenland show very similar basalt compositions and evolution patterns with time the faeroes lower basalt formation and the equivalent nansen fjord formation in east greenland form a pre break up succession overlain by a sediment horizon a syn break up succession consists of the faeroes middle and upper basalt formations and the equivalent milne land formation in east greenland in which five intervals can be correlated with a compositional evolution from ti rich magnesian basalts and picrites at the base to a dominance of morb like low ti basalts at the top the successions were generated in the same mantle melting column beneath a thinning continent with a rift zone that eventually ruptured the continent the evolution pattern is very similar to that seen on the se greenland margin but spreading according to the palmason model of 1973 was not yet established the pre and syn break up successions formed volcanic megasystems stretching across the rift zone with areal extents of 70 000 and 220 000 km 2 and volumes of 120 000 and 250 000 km 3 rocks from the pre and syn break up successions can be discriminated based on a simple major element plot the overlying succession was 3 3 5 km thick in e greenland but was thin or absent in the faeroes the energy source for the melting appears to have been concentrated on the greenland side

hydrocarbon reserves of gachsaran oilfield sw iran geochemical characteristics and origin abstract biomarkers and carbon isotope data were used to depict geochemical properties and to delineate source of the crude oils from asmari and bangestan reservoirs of the giant gachsaran oilfield sw iran despite the distinct horizons of the reservoirs and severe petrophysical heterogeneity inside each reservoir all oil samples show an identical level of thermal maturity furthermore similar source related parameters reflect identical source rock for both reservoirs they indicate carbonate marl source deposited in a marine environment under anoxic suboxic conditions strong marine organic matter signatures of predominantly algal origin along with evidence of a terrigenous angiosperm plant contribution were detected geochemical evidence suggests that the gachsaran field asmari and bangestan oils being sourced from a mix of organic rich kazhdumi and pabdeh source rocks of albian and middle eocene early oligocene ages respectively carbon isotope composition and v ni ratio signatures indicate kazhdumi formation as the main source rock meanwhile significant presence of oleanane and less than unity values of c 29 c 30 hopanes ratio demonstrate a partial contribution of pabdeh formation this contradiction could be explained by two scenarios 1 incorporating very immature non expelled pabdeh oils into the mature kazhdumi oils during migration or 2 partial charge form low maturity pabdeh oils that is insufficient to impact a typical mixed signature over the geochemical fingerprint of the reservoired oils additionally geochemical similarities give rise to an assumption of reservoir and trap inter connection for this giant field

tracing early charged oils and exploration directions for the wenchang a sag western pearl river mouth basin offshore south china sea the wenchang a sag is the largest petroleum producing sub depression in the western pearl river mouth basin offshore south china sea the eocene wenchang formation and the early oligocene enping formation are the two major source rocks in the sag the oil discoveries in this region mainly originated from the enping fm how to objectively estimate the petroleum potential of the wenchang fm and trace the wenchang oils has long been the focus of research and exploration in this region in this paper inclusion oils obtained from reservoir sandstones as well as typical reservoir oils and potential source rocks were investigated by systematic geochemical methods oil oil and oil source rock correlations indicate that inclusion oils in the central and marginal areas of the wenchang a sag had similar geochemical characteristics and mainly originated from the wenchang source rocks the reservoir oils in the central area are derived mainly from the enping source rocks while in the marginal areas they have mixed characteristics of both the enping and wenchang formations combining the tectonic sedimentary evolution and petroleum generation histories it is concluded that the two source rocks in the wenchang a sag have generated oils but in the central areas the main stage of oil generation of the wenchang fm was much earlier than the formation time of the traps resulting in the dissipation of most of the early generated wenchang sourced oils in the marginal areas the main stage of oil generation of the wenchang fm was later and the wenchang oils not only could be captured as fluid inclusions in the reservoir quartz grains but also migrated and accumulated into oil pools in which they mixed with the enping sourced oils the early lithological and structural traps in the central and marginal areas of the wenchang a sag especially in the northern part of the shenhu uplift are the most prospective areas for further exploration of the sag

reducing ionospheric effects in insar data using accurate coregistration interferometric synthetic aperture radar insar is a valuable tool for the study of geophysical phenomena such as crustal deformation ice motion and structure and vegetation canopy depths but it is adversely affected by uncharacterized inhomogeneities in ionospheric propagation delay ionospheric disturbances distort both insar phase and correlation maps here we present a method to compensate ionospheric propagation variations using accurate image coregistration this significantly improves both the interferometric coherence and phase accuracy an azimuth gradient in the total electron content tec from a spatially variable ionosphere results in a range dependent azimuth phase gradient being added to the phase histories of the pixels being imaged these phase gradients are equivalent to doppler shifts and thus they cause azimuth offsets between the actual and imaged positions of the pixels measuring these offsets accurately permits estimation of the gradient and correction of the interferograms for much of the phase distortion resulting in more accurate estimates of coherence we show an example over greenland where the tec variation causes the correlation to drop from about 0 7 to about 0 2 in one region if spatially varying offsets are not accounted for it also adds an estimated 4 4 radians of interferometric phase over an 80 km insar scene after applying our algorithm we find that the correlation in regions affected by the ionospheric inhomogeneity becomes comparable to correlation in the rest of the image in a more challenging example over iceland we show that our method improves the correlation from 0 15 to 0 25 in some areas

spatial and temporal variability of paleocene miocene organofacies of the kura basin eastern azerbaijan and implications for basin evolution and petroleum generation abstract fine grained paleocene miocene strata of eastern azerbaijan record the evolution of the kura basin from an open marine system connecting the south caspian basin to the paratethys of eastern europe to an isolated epicontinental sea tectonic uplift associated with the greater caucasus mountains in azerbaijan resulted in exposure of these strata over much of the northeastern part of the basin allowing detailed observation and sampling over a broad area four hundred paleocene miocene samples collected in eastern azerbaijan demonstrate spatial and temporal geochemical heterogeneity within the predominately mudstone succession indicating a complex evolution of this elongate basin through detailed organic geochemical analysis of samples trends can be seen in the distribution of total organic carbon toc pyrolysis characteristics and biomarker results from a subset of twenty four samples in addition to confirming the well documented regional basin restriction during the oligocene to early miocene deposition of the maikop series heterogeneity of these geochemical indicators across the study area shows spatial variability in oxicity and terrestrial organic input within the basin on a sub regional scale observed geochemical variability suggests a complex evolutionary history of the kura basin during the paleocene miocene and this has important implications for hydrocarbon prospectivity in the region within the 400 collected samples total organic carbon toc values range from 0 3 to 6 3 with oligocene miocene samples showing average values of 1 4 compared to lower toc values found in paleocene eocene strata average 0 3 rock eval pyrolysis shows that the majority of strata are organic lean immature and mixed oil gas to gas prone type ii iii to type iii with a smaller group of latest eocene early miocene samples having better oil prone source potential gas chromatography and biomarker analysis of 24 samples reinforces the immaturity of most samples shows varying levels of terrestrial input in all samples suggests well oxygenated waters prevailed with periodic suboxic to dysoxic anoxic events highlights gross differences between the paleocene eocene and oligocene miocene stratigraphic intervals and shows generally good lateral correlation between samples these interpretations reinforce what is seen through inorganic geochemical evaluation of trace metals bulk composition and stable isotopic ratios and offer more detail as to the evolution of this basin and the implications for oil and gas prospectivity of the region

stochastic synthesis of earthquake catalogs a model of earthquake occurrence is proposed that is based on results of statistical studies of earthquake catalogs we assume that each earthquake generates additional a probability that depends on time as t 1 this assumption together with one regarding the independence of branching events on adjacent branches of the event tree is sufficient to permit the generation of complete catalogs of earthquakes that have the same time magnitude statistical properties as real earthquake catalogs if is about 0 5 the process generates sequences that have statistical properties similar to those for shallow earthquakes many well known relations are reproduced including the magnitude frequency law omori s law of the rate of aftershock and foreshock occurrence the duration of a recorded seismic event versus its magnitude the self similarity or lack of scale of rate of earthquake occurrence in different magnitude ranges etc a value of closer to 0 8 or 0 9 seems to simulate the statistical properties of intermediate and deep shocks a formula for seismic risk prediction is proposed and the implications of the model for risk evaluation are outlined the possibilities of the determination of long term risk from real or synthetic catalogs that have the property of self similarity are dim

current deformation in the northern canadian cordillera inferred from gps measurements 1 continuous and campaign style global positioning system gps measurements provide new constraints on the first order current deformation pattern of the northern cordillera of nw canada and eastern alaska the yakutat block is currently colliding with north america in the corner of the gulf of alaska our data infer that relative yakutat north america motion is accommodated across the eastern boundary by right lateral motion 40 mm a mainly on the fairweather fault and minor shortening 6 mm a to the north collision is taken up by shortening 31 mm a mainly on the chugach st elias fault system with westward extrusion and possible counterclockwise rotation of the yakutat block and alaskan fore arc facilitated by 23 mm a right lateral motion that is shared by several faults the seismicity pattern indicates that plate boundary deformation is far reaching producing strain throughout eastern alaska yukon and western northwest territories our gps data confirm the transfer of strain from the yakutat collision zone and enable the extent of plate boundary deformation to be mapped thereby defining the western edge of stable north america gps sites in sw yukon show motion of 3 10 mm a to the ne confirming that strain is transferred at least 400 km from the yakutat collision continued transfer north toward the mackenzie delta and ne to the mackenzie mountains indicated by current seismicity is not yet well resolved by the campaign gps data which are hampered by coseismic and postseismic effects of the 2002 mw 7 9 earthquake on the denali fault in eastern alaska

acoustic scattering losses in the greenland sea marginal ice zone during the 1988 89 tomography experiment using arrival amplitude data from the 1988 89 greenland sea tomography experiment the effects of ice scattering at 250 hz in the marginal ice zone miz are estimated the resolution of the arrivals is examined first showing that arrivals are resolved as rays from about 8 to 13 launch angle and a normal modes for low angles below about 4 launch angle the under ice reflection losses of resolved rays and modes are then considered using two methods first the ratio of arrival amplitudes during ice free and ice covered periods is estimated second the ratio of members of a ray group with different reflection numbers is used showing similar but not identical results to the first method for higher grazing angle reflections fast field calculations using the program safari are observed to model the data reasonably using a combination of measured and historical ice parameter values for the low angle arrivals the amplitudes of the arrivals are observed to depend strongly upon both the details of th

active tectonics of the st elias orogen alaska observed with gps measurements 1 we use data from campaign and continuous gps sites in southeast and south central alaska to constrain a regional tectonic block model for the st elias orogen active tectonic deformation in the orogen is dominated by the effects of the collision of the yakutat block with southern alaska our results indicate that 37 mm yr of convergence is accommodated along a relatively narrow belt of n nw dipping thrust faults in the eastern half of the orogen with the present day deformation front running through icy bay and beneath the malaspina glacier near the bering glacier the collisional thrust fault regime transitions into a broad northwest dipping decollement as the yakutat block basement begins to subduct beneath the counterclockwise rotating elias block the location of this transition aligns with the gulf of alaska shear zone implying that the pacific plate is fragmenting in response to the yakutat collision our model indicates that the bering glacier region is undergoing internal deformation and could correspond to the final stage of offscraping and accretion of sediments from the yakutat block prior to subduction predicted block motions at the western edge of the orogen suggest that the crust is laterally escaping along the aleutian fore arc

on the effects of small scale variability on acoustic propagation in fram strait the tomography forward problem acoustic tomography systems have been deployed in fram strait over the past decade to complement existing observing systems there the observed acoustic arrival patterns are unusual however consisting of a single broad arrival pulse with no discernible repeating patterns or individual ray arrivals the nature of these arrivals is caused by vigorous acoustic scattering from the small scale processes that dominate ocean variability in fram strait simple models for internal wave and mesoscale variability were constructed and tailored to match the variability observed by moored thermisters in fram strait the internal wave contribution to variability is weak acoustic propagation through a simulated ocean consisting of a climatological sound speed plus mesoscale and internal wave scintillations obtains arrival patterns that match the characteristics of those observed i e pulse width and travel time variation the scintillations cause a proliferation of acoustic ray paths however reminiscent of ray chaos this understanding of the acoustic forward problem is prerequisite to designing an inverse scheme for estimating temperature from the observed travel times

denali fault slip rates and holocene late pleistocene kinematics of central alaska the denali fault is the principal intracontinental strike slip fault accommodating deformation of interior alaska associated with the yakutat plate convergence we obtained the first quantitative late pleistocene holocene slip rates on the denali fault system from dating offset geomorphic features analysis of cosmogenic 10be concentrations in boulders n 27 and sediment n 13 collected at seven sites offset 25 170 m by the denali and totschunda faults gives average ages that range from 2 4 0 3 ka to 17 0 1 8 ka these offsets and ages yield late pleistocene holocene average slip rates of 9 4 1 6 12 1 1 7 and 8 4 2 2 mm yr 1 along the western central and eastern denali fault respectively and 6 0 1 2 mm yr 1 along the totschunda fault our results suggest a westward decrease in the mean pleistocene holocene slip rate this westward decrease likely results from partitioning of slip from the denali fault system to thrust faults to the north and west

basin evolution in southern east greenland an outcrop analog for cretaceous paleogene basins on the north atlantic volcanic margins the cretaceous paleogene kangerlussuaq basin in southern east greenland represents a unique outcrop analog for the frontier petroleum provinces along the deep water volcanic margins of the northern north atlantic the 1 km thick sedimentary succession comprises six facies associations 1 alluvial plain and shallow marine late aptian 2 fluvio estuarine late aptian early albian 3 offshore marine late cretaceous early paleocene 4 submarine fan and channel levee early paleocene 5 fluvial mid paleocene and 6 volcanic late paleocene sedimentation was terminated in the late paleocene by extrusion of flood basalts related to continental breakup the basin fill is divided into two depositional megasequences related to regional tectonic events and sea level changes the oldest megasequence sq1 spans the late aptian to the earliest paleocene with sea level rise in the late aptian and maximum flooding in the late albian cenomanian followed by sea level highstand in the late cretaceous early paleocene sq1 is truncated by a basin wide unconformity related to regional uplift and basin reorganization in the mid paleocene the upper megasequence sq2 spans the mid to late paleocene and comprises sediments deposited during early sea level rise extensive volcanic deposits and continental flood basalts overlie it deep burial 6 km and middle eocene early oligocene uplift excludes the kangerlussuaq basin as a petroleum basin in itself however to evaluate the petroleum potential of similar volcanic influenced offshore basins such as the west shetland faeroe more and voring basins we discuss three conceptual play models based on the kangerlussuaq basin 1 early albian stratigraphic trap 2 early paleocene structural trap and 3 paleocene stratigraphic trap

modeled acoustic propagation through an ice edge eddy in the east greenland sea marginal ice zone a detailed modeling study of the relationship between the various oceanographic features of a cyclonic eddy located at the ice edge off the coast of northeastern greenland and the eddy s effects on the propagation of acoustic energy is presented the effects of the eddy on acoustic propagation as a function of location depth and frequency of the acoustic source and depth of the receiver for nominal frequencies of 50 hz and 1 khz are discussed significant differences sometimes greater than 20 db in the acoustic field were observed for variations in any of the source and receiver parameters the sound speed structure of the eddy makes propagation loss and acoustic modes very dependent on direction and location a significant finding is that the interior environment of the eddy can generate a frequency dependence on propagation loss so that 1 khz sustains a loss as much as 20 db smaller than does 50 hz i e dispersion phenomenon a similar propagation loss anomaly was observed and appears to be due to a combination of marginal ice zone miz fine structure and interference patterns created by reflections from the sea surface such an anomaly can exist in the miz with or without the eddy environment both of these frequency anomalies are a function of source and receiver depth low frequency 50 hz energy in the presence of the eddy can experience stronger downward refraction and thereby possibly suffer greater bottom interaction than high frequencies 1 khz as compared to the noneddy environment propagation in the presence of the eddy for any of the source and receiver depths studied can result in changes in the levels and distribution of energy in the acoustic field by more than 10 db as well as changes in the mode of propagation of some rays e g refracted surface reflected to refracted refracted

source parameters of the 2017 m w 6 2 yukon earthquake doublet inferred from coseismic gps and alos 2 deformation measurements we investigated an m w 6 2 earthquake doublet on the border of the usa and canada using alos2 light of sight displacements and gps measurements we selected three l band alos 2 interfergorams with temporal baselines of one yr to extract coseismic deformation maps in which master and slave images were both acquired in july a subpixel based alignment and another range spectral splitting techniques under the gamma insar software framework were applied to improve the interferometric coherence and reduce the effects of phase anomalies in two of the three interferometric pairs due to either ionospheric delay or a potential focusing issues in the generation of the alos2 slc data the updated interferograms convincingly reveal deformation fringe patterns produced by the two earthquakes we conducted a nonlinear geophysical inversion to estimate the geometric parameters of the earthquakes with the insar and gps measurements the best fitting model shows that a thrust faulting on a reverse fault and left lateral strike slip faulting on a nearly vertical fault with the centroid depths of 9 3 0 6 and 8 4 0 7 km respectively are most likely responsible for the earthquake doublet the eastern denali fault edf and duke river fault are major active faults in the region and the earthquake doublet could be due to reactivation of the part of the two faults system

unusual biomarker maturation ratio changes through the oil window a consequence of varied thermal history abstract saturated and aromatic biomarker ratios continue to change systematically through the oil window and into the gas condensate window to high vitrinite reflectances r o 1 16 in mature marine and lacustrine mesozoic clastic samples from a south african basin two of the ratios reverse above r o 0 9 these unusual maturation effects result from isolated periods of high rates of maturation increase the basin cooled regionally after the break up of gondwana but high heating rates prevailed during the late cretaceous early tertiary as africa moved across a hotspot and again in the late tertiary as a result of a possible hotspot and hydrothermal event

surface displacements and source parameters of the 2003 bam iran earthquake from envisat advanced synthetic aperture radar imagery 1 the mw 6 6 26 december 2003 bam iran earthquake was one of the first earthquakes for which envisat advanced synthetic aperture radar asar data were available using interferograms and azimuth offsets from ascending and descending tracks we construct a three dimensional displacement field of the deformation due to the earthquake elastic dislocation modeling shows that the observed deformation pattern cannot be explained by slip on a single planar fault which significantly underestimates eastward and upward motions se of bam we find that the deformation pattern observed can be best explained by slip on two subparallel faults eighty five percent of moment release occurred on a previously unknown strike slip fault running into the center of bam with peak slip of over 2 m occurring at a depth of 5 km the remainder occurred as a combination of strike slip and thrusting motion on a southward extension of the previously mapped bam fault 5 km to the east

mesoscale eddies in the fram strait marginal ice zone during the 1983 and 1984 marginal ice zone experiments during the summer marginal ice zone experiment in fram strait in 1983 and 1984 fourteen mesoscale eddies in both deep and shallow water were studied between 78 o and 81on sampling combined satellite and aircraft remote sensing observations conductivity temperature depth observations drift of surface and subsurface floats and current meter measurements typical scales of these eddies were 20 40 km rotation was mainly cyclonic with a maximum speed in several cases subsurface of up to 40 cm s observations further suggest that the eddy lifetime was at least 20 to 30 days five generation sources are suggested for these eddies several of the eddies were topographically trapped while others primarily formed by combined baroclinic and barotropic instability moved as much as 10 15 km d with the mean current the vorticity balance in the nontrapped eddies is dominated by the stretching of isopycnals accompanied by a change in the radial shear in the most completely observed eddy south of 79on the available potential energy exceeded the kinetic energy by a factor of 2 quantitative estimates suggest that the abundance of these eddies enhances the ice edge melt up to 1 2 km d

insar time series estimation of the ionospheric phase delay an extension of the split range spectrum technique repeat pass interferometric synthetic aperture radar insar observations may be significantly impacted by the propagation delay of the microwave signal through the ionosphere which is commonly referred to as ionospheric delay the dispersive character of the ionosphere at microwave frequencies allows one to estimate the ionospheric delay from insar data through a split range spectrum technique here we extend the existing split range spectrum technique to insar time series we present an algorithm for estimating a time series of ionospheric phase delay that is useful for correcting insar time series of ground surface displacement or for evaluating the spatial and temporal variations of the ionosphere s total electron content tec experimental results from stacks of l band sar data acquired by the alos 1 japanese satellite show significant ionospheric phase delay equivalent to 2 m of the temporal variation of insar time series along 445 km in chile a region at low latitudes where large tec variations are common the observed delay is significantly smaller with a maximum of 10 cm over 160 km in california the estimation and correction of ionospheric delay reduces the temporal variation of the insar time series to centimeter levels in chile the ionospheric delay correction of the insar time series reveals earthquake induced ground displacement which otherwise could not be detected a comparison with independent gps time series demonstrates an order of magnitude reduction in the root mean square difference between gps and insar after correcting for ionospheric delay the results show that the presented algorithm significantly improves the accuracy of insar time series and should become a routine component of insar time series analysis

atmospheric effects in interferometric synthetic aperture radar surface deformation and topographic maps interferogram images derived from repeat pass spaceborne synthetic aperture radar systems exhibit artifacts due to the time and space variations of atmospheric water vapor other tropospheric variations such as pressure and temperature also induce distortions but the effects are smaller in magnitude and more evenly distributed throughout the interferogram than the wet troposphere term spatial and temporal changes of 20 in relative humidity lead to 10 cm errors in deformation products and perhaps 100 m of error in derived topographic maps for those pass pairs with unfavorable baseline geometries in wet regions such as hawaii these are by far the dominant errors in the spaceborne imaging radar c and x band synthetic aperature radar sir c x sar interferometric products the unknown time delay from tropospheric distortion is independent of frequency and thus multiwavelength measurements such as those commonly used to correct radar altimeter and global positioning system gps ionospheric biases cannot be used to rectify the error in the topographic case the errors may be mitigated by choosing interferometric pairs with relatively long baselines as the error amplitude is inversely proportional to the perpendicular component of the interferometer baseline for the sir c x sar hawaii data we found that the best longest baseline pair produced a map supporting 100 m contouring whereas the poorest baseline choice yielded an extremely noisy topographic map even at this coarse contour interval in the case of deformation map errors the result is either independent of baseline parameters or else very nearly so here the only solution is averaging of independent interferograms so in order to create accurate deformation products in wet regions many multiple passes may be required rules for designing optimal data acquisition and processing sequences for interferometric analyses in nondesert parts of the world are 1 to use the longest radar wavelengths possible within ionospheric scintillation and faraday rotation limits 2 for topography maximize interferometer baseline within decorrelation limits and 3 for surface deformation use multiple observations and average the derived products following the above recipe yields accuracies of 10 m for digital elevation models and 1 cm for deformation maps even in very wet regions such as hawaii

the fram strait acoustic tomography system the deep and wide fram strait between greenland and spitzbergen is the main influx and efflux gate to the arctic basin although major resources are invested in measurements of current and temperature here http asof npoar no the flux estimates still have significant deficiencies and errors our objective is to build test validate and use an innovated integrated observing and modeling system including acoustic tomography for improved monitoring of volume heat and freshwater transports in the fram strait as part of the damocles ip developing arctic modeling and observing capabilities for long term environmental studies integrated project a first step acoustic tomography system is to be installed in the fram strait between east greenland and west spitzbergen in august 2008 the first step tomography system consists of one acoustic source near the svalbard shelf and one receiver array in the middle of the fram strait an extended acoustic system serving both tomography and glider navigation i

the 2011 mw 6 8 burma earthquake fault constraints provided by multiple sar techniques we used two tracks of alos palsar images to investigate the focal mechanism and slip distribution of the 2011 march 24 m w 6 8 burma strike slip earthquake three different sar techniques namely conventional interferometry sar pixel offsets spo and multiple aperture insar mai were employed to obtain the coseismic surface deformation fields along the 30 km length of the fault rupture along track measurements from spo and mai techniques show a high correlation and were subsequently used to precisely determine the location and extent of the surface fault trace the best fitting fault model geometry derived from an iterative inversion technique suggests that the rupture occurred on a near vertical sinistral strike slip fault west of the nam ma fault with a strike of 70 a maximum slip of 4 2 m occurs at a depth of 2 5 km with significant slip constrained only to the upper 10 km of the crust

on the use of fractal surfaces to understand seismic wave propagation in layered basalt sequences the aim of this study is to better understand how a layered basalt sequence affects the propagation of a seismic wave which has implications for sub basalt seismic imaging this is achieved by the construction of detailed realistic models of basalt sequences using data derived directly from outcrop analogues field data on the surface roughness of basaltic lava flows were captured using terrestrial laser scanning and satellite remote sensing the fractal properties of the surface roughness were derived and it can be shown that the lava flow surface is fractal over length scales up to approximately 2 km the fractal properties were then used to construct synthetic lava flow surfaces using a von karman power spectrum and the resulting surfaces were then stacked to create a synthetic lava flow sequence p wave velocity data were then added and the resulting model was used to generate synthetic seismic data the resulting stacked section shows that the ability to resolve the internal structure of the lava flows is quickly lost due to scattering and attenuation by the basalt pile a further result from generating wide angle data is that the appearance of a lower velocity layer below the basalt sequence may be caused by destructive interference within the basalt itself

ice edge eddies in the fram strait marginal ice zone five prominent ice edge eddies in fram strait on the scale of 30 to 40 kilometers were observed over deep water within 77 n to 79 n and 5 w to 3 e the use of remote sensing a satellite tracked buoy and in situ oceanographic measurements showed the presence of eddies with orbital speeds of 30 to 40 centimeters per second and lifetimes of at least 20 days ice ablation measurements made within one of these ice ocean eddies indicated that melting which proceeded at rates of 20 to 40 centimeters per day is an important process in determining the ice edge position these studies give new insight on the formation propagation and dissipation of ice edge eddies

effects of sea ice cover on acoustic ray travel times with applications to the greenland sea tomography experiment the travel time effects of a sea ice cover on an acoustic pulse are estimated using generalized ray theory this expands upon the previous work done by jin and wadhams prog oceanogr 22 249 275 1989 by including the effects of frequency dispersion and different sets of ice parameters travel time changes due to single reflections are approximated by plane wave reflection theory and compared to the generalized ray theory results statistical effects for multiple reflections such as the ice thickness probability distribution function fresnel zone averaging and shadowing are considered finally the effects of ice induced travel time changes on tomographic inversions for water column oceanography are considered the implications of this work on the 1988 89 greenland sea tomography experiment are considered in detail

do earthquakes talk to each other triggering and interaction of repeating sequences at parkfield 1 knowledge of what governs the timing of earthquakes is essential to understanding the nature of the earthquake cycle and to determining earthquake hazard yet the variability and controls of earthquake recurrences are not well established the large population of small characteristically repeating earthquakes at parkfield provides a unique opportunity to study how the interaction of earthquakes affects their recurrence properties we analyze 112 m 0 4 3 0 repeating earthquake sequences ress to examine the triggering effect from nearby microseismicity we find that the repeating events with a smaller number of neighboring earthquakes in their immediate vicinity tend to recur in a more periodic manner i e the coefficient of variation in recurrence intervals is less than 0 3 the total static stress perturbation from close by earthquakes however does not seem to strongly influence res regularity the uneven distribution of stress changes in time has a modest but significant impact on recurrence intervals a significant reduction of recurrence intervals occurs in the case of very high stress changes from neighboring events close by events influence res timing in a matter of several days or less by short term triggering events that occurred within less than 1 day of an res often imposed or experienced high stress changes a static stress increment of 30 kpa can be enough to produce such short term triggering we find that the triggered repeating events are often near the end of their average earthquake cycle but some events occur following a substantially shortened interval when comparing the accelerated occurrence at the time of res events following neighboring events with varying magnitudes we find that the distance of short term triggering increases from 1 km to 4 km for m1 to m4 events

acoustic propagation in the western greenland sea frontal zone a study utilizing numerical experiments of the environmental acoustic effects of the western greenland sea frontal zone in the summer of 1983 along a 185 km west to east transect is presented the transect begins at the edge of the marginal ice zone in the east greenland current then crosses the east greenland polar front and terminates in the water of the greenland sea gyre the transect contains several mesoscale eddylike features and a sharp front between return atlantic intermediate water and greenland arctic intermediate water whose effects on an acoustic field have not been previously reported this front can impart 15 db increase in loss in 10 db in the sensitivity of propagation loss to changes in receiver depth 10 150 m compared to the nonfrontal zone environment a significant finding is that a longer transmission range 93 km through the waters of a frontal zone can reduce the effects of crossing the front itself by as much as 15 db it was also observed that 75 km of upslope propagation that included two oceanic fronts was unaffected by a decrease in bottom depth of 2000 m within the 75 km range

strain accumulation across the fairweather and totschunda faults alaska deformation across the fairweather and totschunda faults is estimated from repeated surveys of geodetic networks that span those faults surveys in 1967 1983 and 1986 of networks crossing the fairweather fault indicate that right lateral engineering shear strain is accumulating across the 1958 earthquake rupture at a rate of 1 6 0 2 rad yr this rate of deformation is one of the highest observed across a strike slip fault system and it is several times greater than the secular rate of deformation across locked parts of the san andreas fault the rate of strain accumulation across the fairweather fault was the same in the two intervals 1967 1983 and 1983 1986 and is thus believed to be a secular rate rather than a transient associated with the 1958 earthquake the 1983 1986 line length changes are best fit by a model fault that is locked from the surface to a depth of 7 to 9 km and is slipping in a right lateral sense at a rate of 41 to 51 mm yr below that depth models with the fault locked to any depth of 4 km fit the data almost equally well the best fitting models indicate a slip rate comparable to the 48 to 58 mm yr average late holocene slip rate indicated by offset glacial moraines and to the 54 mm yr component of relative motion between the pacific and north american plates that is parallel to the fairweather fault no significant contraction was measured across the fairweather fault only a small part of the relative plate motion is transferred across the saint elias mountains to the colinear totschunda fault surveys in 1909 1912 and 1985 of a geodetic network that extends for 72 km across the totschunda fault indicate right lateral shear strain is accumulating at a rate of 0 11 0 06 rad yr this rate of strain accumulation suggests a slip rate of about 10 mm yr on the totschunda fault a value at the lower end of the average holocene slip rate of 10 to 20 mm yr

the influence of facies and depositional environment on the occurrence and distribution of carbazoles and benzocarbazoles in crude oils a case study from the gulf of suez egypt abstract two major hinge zones separate the gulf of suez gos of egypt into three tectonic sub provinces namely the northern central and southern sectors based on bulk and molecular parameters the crude oils from the gos can be subdivided into three groups according to their geographical origin from the three sectors the geochemical characteristics of the oils are consistent with inferred depositional environments of anoxic marine carbonate facies in the central sector compared to a more oxic environment that has received an increased proportion of clastic input in the southern sector while the northern is intermediate in character most of the oils cover a relatively narrow maturity range 0 86 0 98 r c in the peak oil window the biomarker parameter ts ts tm is controlled by variations of facies and depositional environment but not by maturity concentrations of pyrrolic nitrogen compounds in the gos crude oils are in general relatively low but show a large range of variability in crude oils of the northern sector a strong predominance of c 4 and c 5 carbazoles over the lower homologues is observed towards the south the relative abundance of carbazole and the methylcarbazoles increases successively variations within the methylcarbazoles and c 2 carbazoles are rather small and therefore are not useful for a straightforward classification of oil families however atypical patterns in some of the oils particularly from the northern sector give evidence for contributions from yet unidentified local sources which might not be of general importance in the gos petroleum province benzo b carbazole is near or even below detection limit in the gos crude oils the benzocarbazole a a c ratio shows a consistently positive correlation with api gravity pr ph and ts ts tm and a negative correlation with the sulphur content based on these observations it is inferred that facies and depositional environment of the relevant source rocks are the major factors influencing the benzocarbazole distributions in the central sector of the gos in which oils are predominantly sourced from carbonates deposited under strongly reducing conditions a a c values are mainly below 0 5 in the southern sector where source rocks were deposited under less reducing conditions and received significant clastic input as well as in the northern sector the a a c values are mainly above 0 5

contrasting seismic characteristics of three major faults in northwestern canada the lithoprobe slave northern cordillera lithospheric evolution snorcle profiles crossed three major tectonic zones of the northwestern canadian shield and northern canadian cordillera that are diverse in age and in depth of penetration the oldest 2630 2590 ma the yellowknife river fault zone formed as a strike slip fault in a tensional strain regime reflector attenuation or truncations align vertically beneath the fault trace through much of the crust implying a near vertical fault plane the youngest 60 10 ma the tintina fault zone produced cumulative dextral strike slip displacements of 425 km perhaps 800 km tomographic velocity and ray trace models of reflection data indicate that several fault splays form a tectonic zone 30 km wide at the surface but truncations of deeper crustal reflections suggest that the zone thins in the mid crust and widens near the moho this apparent variable width versus depth of the tintina fault is atypical of major strike slip faults worldwide the teslin fault was an active terrane boundary during accretion of terranes onto north america observed reflection geometries indicate that the juxtapositions of highly contrasting metamorphic grades across the teslin fault are confined to the upper crust along snorcle line 3 implying that the fault soles eastward into a mid crustal detachment at the interpreted top of north american crust the limited depth extent of the teslin fault zone is similar to some models of the san andreas fault and may result from their similar histories as convergent margin structures

geodetic constraints of the 2017 m w 7 3 sarpol zahab iran earthquake and its implications on the structure and mechanics of the northwest zagros thrust fold belt

the 2010 mw 6 8 yushu qinghai china earthquake constraints provided by insar and body wave seismology 1 by combining observations from satellite radar body wave seismology and optical imagery we have determined the fault segmentation and sequence of ruptures for the 2010 mw 6 8 yushu china earthquake we have mapped the fault trace using displacements from sar image matching interferometric phase and coherence and 2 5 m spot 5 satellite images modeling the event as an elastic dislocation with three segments fitted to the fault trace suggests that the southeast and northwest segments are near vertical with the central segment dipping 70 to the southwest slip occurs mainly in the upper 10 km with a maximum slip of 1 5 m at a depth of 4 km on the southeastern segment the maximum slip in the top 1 km i e near surface is up to 1 2 m and inferred locations of significant surface rupture are consistent with displacements from sar image matching and field observations the radar interferograms show rupture over a distance of almost 80 km much larger than initial seismological and field estimates of the length of the fault part of this difference can be attributed to slip on the northwestern segment of the fault being due to an mw 6 1 aftershock two hours after the main event the remaining difference can be explained by a non uniform slip distribution with much of the moment release occurring at depths of less than 10 km the rupture on the central and southeastern segments of the fault in the main shock propagated at a speed of 2 5 km s southeastward toward the town of yushu located at the end of this segment accounting for the considerable building damage strain accumulation since the last earthquake on the fault segment beyond yushu is equivalent to an mw 6 5 earthquake

lithospheric structure of the gorringe bank insights into its origin and tectonic evolution 1 the gorringe bank is a 5000 m high seamount near the atlantic coast of iberia characterized by a 9 m high geoid anomaly and a 120 mgal bouguer anomaly relative to the surrounding abyssal plains it has been linked to a nw directed thrust carrying exhumed upper mantle rocks and transitional crust on top of flexed down eurasian oceanic crust along the tagus abyssal plain however estimations of crustal shortening have yielded dissimilar results and the deep structure of the ridge remains highly unknown we present a restored cross section and a new model of the lithospheric structure based on gravity geoid elevation and the presence of serpentinized peridotites at least 20 km of shortening took place along a flat ramp flat thrust fault and the density structure of the lithosphere is consistent with mantle serpentinization varying from 70 at the surface to 20 at 14 km depth and 0 at 40 km the topographic relief and gravity anomalies are explained by assuming a flexural isostatic model with an elastic thickness te of 30 km the evolution of the gorringe bank since the late jurassic is interpreted in relation to eurasia africa north america plate motion in four stages 1 transtension between newfoundland iberia and africa which generated small oceanic basins and mantle exhumation 2 opening of the north atlantic and seafloor spreading at the nw side of the exhumed gorringe which produced gabbro intrusions and serpentinization 3 a quiescent tectonic period dominated by subsidence and sediment accumulation and 4 a transpressional plate boundary between eurasia and africa with nw directed subcrustal thrusting and generation of the present gorringe relief

the habit and origin of siderite spherules in the eocene coal bearing prestfjall formation faroe islands abstract siderite spherules are described and chemically analysed from two localities holi i helli section and rokhagi coal mine within the coal bearing prestfjall formation the formation marks a significant hiatus in the eruption of lava flows of the paleogene faroe islands basalt group and shortly follows the paleocene eocene thermal maximum the spherules are chemically pure although feco 3 80 6 99 2 mol shows a marked substitution for mnco 3 0 1 13 9 mol the low concentrations of mgco 3 0 0 0 4 mol and the lack of associated sulphide minerals e g pyrite confirm the freshwater lake environment affinity of the formation the siderite spherules from the holi i helli section contain significantly higher concentrations of mnco 3 3 may also account for the abundance of siderite spherules formed by the split crystal process in the holi i helli section whereas prefect spherules consisting of individual crystals growing concentrically around a cryptocrystalline centre are dominant from the rokhagi coal mine

the jurassic petroleum system north and west of britain a geochemical oil source correlation study abstract recent significant oil discoveries have focused exploration attention on the atlantic margin areas north and west of britain in particular the west of shetlands area these discoveries the foinaven and schiehallion fields each have reserves of 250 to 500 million barrels 39 8 to 79 5 106 m3 of 24 27 api oil while an earlier heavy oil discovery the clair field is the largest undeveloped oil discovery on the u k continental shelf with resources estimated in the range 3 5 billion barrels 477 to 795 106 m3 other discoveries include suilven the very heavy oil in well 204 28 1 and the quadrant 205 strathmore and solan fields potential source rocks in areas adjacent to the west of shetlands include the upper jurassic kimmeridge clay formation equivalent the middle and lower jurassic and the middle devonian the results of geochemical studies of the oils reservoir core extracts and source rocks from released wells from these west of shetlands discoveries show them to be genetically related to north sea oils sourced from the kimmeridge clay formation equivalent detailed geochemical analysis biomarkers source rock reaction kinetics compound specific isotope analysis and fluid inclusion crush leach analysis of the clair field and foinaven complex oils showed that at least two episodes of charging from different source facies within the kimmeridge clay formation took place with an intervening biodegradation event oil charging from middle jurassic lacustrine source rocks is also indicated in the foinaven complex oils the source rocks are shown to exhibit variations in organic facies from very oil prone to mixed oil and gas with a corresponding range of kinetic parameters this complex generation migration and trapping scenario is directly linked with the tectonic evolution of the west of shetlands with major oil generation from very oil prone kimmeridge clay and middle jurassic lacustrine facies into shallow buried reservoirs biodegradation of the oils appears to have occurred shortly after migration into the traps followed later by a second charge of unaltered oil this appears to have been from a different source facies with more terrestrial slower reacting type ii iii kerogens similar to those seen in the kimmeridge clay formation or heather formation in wells on the basin margins kinetics studies show the middle and upper jurassic kerogens to be fast reacting and very oil prone with little potential for later gas generation this finding appears crucial in the understanding of the west of shetlands petroleum system as it explains the lack of large gas accumulations in a basin of such high thermal maturity

quantitative assessment to the impact of insar ionospheric and tropospheric corrections on source parameter modelling application to the 4th nuclear test north korea

deep petroleum occurrences in the lower kura depression south caspian basin azerbaijan an organic geochemical and basin modeling study abstract high sedimentation rates as much as 2500 m ma during pliocene pleistocene with a resultant undercompacted section as thick as 10 000 m and lower than normal geothermal gradients are the main characteristics which have created all the means for generation and preservation of oil at deep layers in the lower kura depression oils collected from eight different oil fields for analyses seem to have originated from a common source rock which probably is clastic deposited in relatively subanoxic to suboxic transitional marine environment receiving low to moderate input of terrestrial organic matter oils from shallow a computer aided basin modeling study has been carried out to outline the spatial variation of the oil window and thus help in further identification of possible source rocks for the reservoired oil in the lower kura depression results suggest that the potential hydrocarbon source horizons of the miocene and pliocene red bed series of the so called productive succession are even at depocenter areas immature with respect to oil generation and thus are very unlikely to have been source rocks for the reservoired oils however the oligocene lower miocene maykop rocks are marginally mature to mature depending on locality and the eocene and older rocks are mature with respect to oil generation at all representative field locations oil generation commenced at the end of pliocene and continues at present at depths between 6000 and 12 000 m an unusually deep 10 000 m oil window in the depocenter areas has been caused by the depressed isotherms due to extremely high sedimentation rates up to 3000 m ma for the last two million years the main phase of oil generation is taking place at depths greater than what most of the wells in the study are have reached

new gps constraints on the motion of the yakutat block global positioning system gps measurements were made at yakutat on the yakutat terrane of southern alaska to investigate the motion of the yakutat block with respect to the north american plate and to help constrain motion along the fairweather fault the velocity of yakutat derived from the gps data is 44 1 1 9 mm yr toward n37 4 w relative to stable north america the magnitude of this velocity is similar to that of the pacific plate predicted by nuvel1a although there is a significant difference in the azimuth of these two vectors the motion of yakutat relative to north america is almost exactly parallel to the strike of the fairweather fault suggesting that most deformation inboard of yakutat is right lateral strike slip on the fairweather fault or faults parallel to it and that significant motion normal to the fairweather fault occurs offshore of yakutat the gps velocity at yakutat is also used to help constrain the slip rate and locking depth of the fairweather fault

tomographic resolution of mesoscale eddies in the marginal ice zone a preliminary study the adequacy of ocean acoustic tomography to resolve mesoscale eddies in the marginal ice zones miz in the vertical plane containing the acoustic multipaths connecting a pair of transceivers is studied using simulation inversions based on realistic eddy profiles obtained from conductivity temperature depth data resolution in this plane is seen to be strongly dependent upon the characteristics of the sound channel for optimal minimum mean square error estimators resolution is directly related to accuracy with better resolution implying higher accuracy for unaided acoustic tomography i e no supplementary measurements using only non bottom interacting paths horizontal and vertical resolution lengths of the order of 40 km and 200 m respectively are found in the upper water column for a transmission range of 150 km the implication is that the horizontal resolution is marginally adequate to resolve miz eddies but the vertical resolution is not since the horizontal scale of the eddies is of the same order whereas the vertical scale is much shorter the incorporation of bottom reflected arrivals is found to improve resolution significantly however the improvement only occurs in the horizontal direction and saturates when more than 14 of these arrivals are included beyond this point additional travel time observations give mostly redundant information on the other hand the disappearance of less stable non bottom interacting ray paths can result in a significant loss of resolution but only vertically the deficiency in vertical resolution is a result of the upward refracting nature of the miz sound channel it is also demonstrated that the inclusion of point temperature measurements on the acoustic transceiver moorings can dramatically increase the vertical resolution of the overall system particularly within a horizontal correlation length of the mooring with the inclusion of satellite radiometry surface temperature measurements adequate vertical resolution is achieved over the entire range considered

some thoughts on the use of insar data to constrain models of surface deformation noise structure and data downsampling repeat pass interferometric synthetic aperture radar insar provides spatially dense maps of surface deformation with potentially tens of millions of data points here we estimate the actual covariance structure of noise in insar data we compare the results for several independent interferograms with a large ensemble of gps observations of tropospheric delay and discuss how the common approaches used during processing of insar data affects the inferred covariance structure motivated by computational concerns associated with numerical modeling of deformation sources we then combine the data covariance information with the inherent resolution of an assumed source model to develop an efficient algorithm for spatially variable data resampling or averaging we illustrate these technical developments with two earthquake scenarios at different ends of the earthquake magnitude spectrum for the larger events our goal is to invert for the coseismic fault slip distribution for smaller events we infer the hypocenter location and moment we compare the results of inversions using several different resampling algorithms and we assess the importance of using the full noise covariance matrix

measuring azimuth deformation with l band alos 2 scansar interferometry we analyze the methods for measuring azimuth deformation with the l band advanced land observing satellite 2 alos 2 scanning synthetic aperture radar scansar interferometry to implement the methods we extract focused bursts from the alos 2 full aperture product which is the only product available for scansar interferometry at present the extracted bursts are properly processed to measure azimuth deformation using interferometric phase we apply the range split spectrum method to scansar to estimate the differential ionospheric phase of the interferogram and take the azimuth derivative of the differential ionospheric phase to mitigate the relative azimuth shift caused by ionosphere for the first time azimuth deformation of a large earthquake april 25 2015 nepal earthquake is nearly completely measured by the l band scansar interferometry with moderate precision the result is validated by the azimuth deformation measured by incoherent cross correlation using a pair of high resolution radarsat 2 images in addition to the final azimuth deformation we show the possibility of processing full aperture scansar product using a burst by burst approach to form regular interferograms we also show the recent strong large scale ionospheric effects on the l band alos 2 scansar interferograms other possible applications of this paper include measuring the movement of glaciers

toward operational compensation of ionospheric effects in sar interferograms the split spectrum method the differential ionospheric path delay is a major error source in l band interferograms it is superimposed to topography and ground deformation signals hindering the measurement of geophysical processes in this paper we proceed toward the realization of an operational processor to compensate the ionospheric effects in interferograms the processor should be robust and accurate to meet the scientific requirements for the measurement of geophysical processes and it should be applicable on a global scale an implementation of the split spectrum method which will be one element of the processor is presented in detail and its performance is analyzed the method is based on the dispersive nature of the ionosphere and separates the ionospheric component of the interferometric phase from the nondispersive component related to topography ground motion and tropospheric path delay we tested the method using various advanced land observing satellite phased array type l band synthetic aperture radar interferometric pairs with different characteristics high to low coherence moving and nonmoving terrains with and without topography and different ionosphere states ionospheric errors of almost 1 m have been corrected to a centimeter or a millimeter level the results show how the method is able to systematically compensate the ionospheric phase in interferograms with the expected accuracy and can therefore be a valid element of the operational processor

mesozoic rocks from the hebrides shelf and implications for hydrocarbon prospectivity in the northern rockall trough abstract shallow boreholes drilled in the west lewis and west flannan basins outer hebrides shelf have proved rocks of probable latest bajocian bathonian to barremian age where previously a mainly permo triassic infill has been assumed the full geological succession of the basins remains unproved although the permo triassic history of the basins may be similar the rocks encountered suggest that the basins may have dissimilar geological histories during the jurassic and early cretaceous lithologies are mainly fine grained poorly sorted sandstones or organic rich mudstones some correlation can be made with the isle of skye and the west shetland area the sandstones are poor hydrocarbon reservoirs but the middle jurassic and ryazanian mudstones although immature where drilled have excellent oil source rock potential and may have generated large amounts of hydrocarbons if they are present at depth in the adjacent northern rockall trough

aseismic creep along the san andreas fault northwest of parkfield ca measured by radar interferometry ers 1 radar images acquired 14 months apart studied by differential radar interferometry show the wide area distribution of aseismic creep along the fault segment northwest of parkfield california a sharp discontinuity in the interferometric phase of less than 2 cm equivalent line of sight displacement extends over 80 km in the differential interferogram coincident with the mapped trace of the active san andreas fault and consistent with the expected and measured fault motion although patterns of strain associated with the transition from locked to creeping are not clearly identifiable a decrease in creep displacement from northwest to southeast along the fault is visible the observations are in agreement with a model of elastic deformation constrained by in situ data that supports a maximum expected deformation signature of 10 mm across the image

resolution identification and stability of broadband acoustic arrivals in fram strait fram strait is the only deep water connection between the arctic and the world oceans an acoustic system for tomography glider navigation and passive listening was installed in the central deep water part of the strait during 2010 2012 with the primary objective of improving the estimates of transport through the strait previous tomographic measurements have relied on the travel times of resolved identified and stable acoustic arrivals the oceanographic conditions and highly variable sea ice in fram strait provide an acoustic environment that differs substantially from those in other tomographic experiments however and results in complex arrival patterns comparisons of the measured arrival patterns with predictions based on hydrographic sections show that it is difficult to resolve and identify individual arrivals in the early part of the arrival patterns in addition the early arrivals are unstable with the arrival structure changing significantly over time later arrivals that are surface reflected bottom reflected tend to be easier to resolve and identify as well as more stable the implication is that inverse methods need to use fluctuations in the overall structure of the early arrivals which tend to sample the ocean similarly in combination with the travel times of the later arrivals

the yakutat terrane dramatic change in crustal thickness across the transition fault alaska we present new constraints on the crustal structure of the yakutat terrane and evidence of the role of the transition fault in southern alaska the yakutat terrane south of yakutat bay includes crystalline crust that is 24 27 km thick overlain by sedimentary units that are 4 5 7 5 km thick the yakutat terrane crustal thickness and velocity structure are consistent with an oceanic plateau origin the southern edge of the yakutat terrane is bounded by the transition fault which is imaged as a near vertical fault zone 1 km wide the transition fault is coincident with a dramatic change in moho depth from 32 km for yakutat oceanic plateau crust to 11 5 km for pacific ocean crust occurring over a horizontal distance of 0 5 km there is no evidence for underthrusting of the pacific ocean crust beneath the yakutat terrane at the transition fault we argue that the yakutat terrane formed on the kula or farallon plate and was later juxtaposed next to younger pacific ocean crust by the transition fault

earthquakes in the pamplona zone yakutat block south central alaska the pamplona zone is a region of complex deformation and moderate seismicity located within the yakutat block a region that has been relatively aseismic since a series of large m 7 8 earthquakes in 1899 in 1970 a sequence of moderate to large sized earthquakes occurred within the pamplona zone largest event of mw 6 7 together with a mw 6 1 event in 1958 these events are the only m 5 5 events known to have occurred in the pamplona region since 1900 thus these events give important information on internal deformational processes within the yakutat block waveform modeling of three earthquakes in april 1970 showed rupture complexity along low angle thrust faults focal depths indicate that two of the events occurred above the wrangell aleutian megathrust while the largest event may have occurred on the megathrust events in 1958 and february 1970 indicate that deformation within the western pamplona zone is occurring along high angle 60 faults with reverse oblique motion we believe the pamplona spur the easternmost part of the pamplona zone may have behaved as an asperity during the 1899 sequence the location of the spur may be influenced by a north south trending fault zone in the subducting pacific plate that appears to be responsible for the 1987 1992 gulf of alaska sequence occurring 50 to 200 km south of the pamplona zone

the heard island feasibility test in january 1991 the heard island feasibility test hift was carried out to establish the limits of usable long range acoustic transmissions coded acoustic signals transmitted from a source near heard island in the southern indian ocean were monitored at 16 sites in the north and south atlantic the north and south pacific the indian ocean and the southern ocean the question posed by hift whether at such global ranges the signals would permit phase coherent processing and thus yield favorable signal to noise levels was answered in the affirmative there was no evidence of distress by the local marine mammal population in response to the acoustic transmissions hift was prerequisite to a program for acoustic thermometry of ocean climate atoc the principal challenges to such a program are discussed

interferometric synthetic aperture radar atmospheric correction using a gps based iterative tropospheric decomposition model abstract atmospheric effects represent one of the major error sources of repeat pass interferometric synthetic aperture radar insar and could mask actual displacements due to tectonic or volcanic deformation the tropospheric delays vary both vertically and laterally and can be considered as the sum of i a vertically stratified component highly correlated with topography and ii a turbulent component resulting from turbulent processes in the troposphere varying both in space and time in this paper we outline a framework to routinely use pointwise gps data to reduce tropospheric effects on satellite radar measurements an iterative tropospheric decomposition itd model is used and further developed to separate tropospheric stratified and turbulent signals and then generate high resolution correction maps for sar interferograms cross validation is employed to assess the performance of the itd model and act as an indicator to users of when and where correction is feasible tests were carried out to assess the impact of gps station spacing on the itd model insar correction performance which provides insights into the trade off between station spacing and the achievable accuracy the application of this framework to sentinel 1a interferograms over the southern california usa and southern england uk regions shows approximately 45 78 of noise reduction even with a sparse 50 80 km station spacing gps network and or with strong and non random tropospheric turbulence this is about a 50 greater improvement than previous methods it is believed that this framework could lead to a generic insar atmospheric correction model while incorporating continuous and global tropospheric delay datasets e g numerical weather models

identification and inversion of converted shear waves case studies from the european north atlantic continental margins summary wide angle shear wave arrivals converted from compressional to shear waves at crustal interfaces enable crustal vp vs ratios to be determined which provide valuable constraint on geological interpretations analysis of the converted shear wave phases represents the next logical step in characterizing the crustal structure and composition following multichannel seismic structural imaging and tomographic inversion of the wide angle compressional wave phases in this offshore study across two passive margins extending from stretched continental to fully oceanic crust the high data density 2 10 km ocean bottom seismometer obs spacing and a consistent efficient conversion interface produced shear wave data sets suitable for traveltime inversion the shear waves were recorded by three orthogonal geophones in each obs arrival phases visible to 180 km offset were identified using their arrival times moveout velocities and particle motions across the north atlantic volcanic rifted continental margins studied breakup was accompanied by the eruption of large volumes of basalts of the north atlantic igneous province the interface between post volcanic sediments and the top of the basalts provides the dominant conversion boundary across the oceanic crust and the continent ocean transition however the shear wave data quality was significantly diminished at the continental ends of the profiles where the thick basalt flows and hence this conversion interface feathers out and crustal attenuation increases initial modelling of the converted shear wave phases was carried out using a layer based approach with arrivals converted on the way up used to constrain the vp vs ratio of the post volcanic sedimentary sequence beneath each obs to produce a model with continuous crustal s wave velocities the compressional wave velocities beneath the sediment top basalt interface were transformed into starting shear wave velocities using a constant value of vp vs and the inversion carried out by specifying the appropriate ray path once the data set had been fully interpreted correction of the traveltimes to effective symmetric ray paths enabled us to apply a regularized grid inversion such inversions are less subjective than the layer based approach and yield more robust minimum structure results with quantifiable errors except in the vicinity of a known subbasalt low velocity zone encountered on the faroes margin monte carlo analyses were performed for this approach the average model from multiple inversions using randomized starting models and traveltimes shows the structure required by the traveltimes and the model standard deviation gives an estimate of uncertainty model and inversion parametrizations were fully tested and optimum parameters chosen for compressional and shear wave inversions this allows after appropriate model smoothing an estimate to be made of the spatial variation of the vp vs ratio within the crust there are marked gradients in vp vs and vp vs ratio across the continent ocean transition which may result from intrusion of high magnesium mafic igneous material into the crystalline continental crust the vp vs ratio used in conjunction with vp also provides constraints on the subbasalt lithologies forming the low velocity zone we conclude from such an analysis that this zone is unlikely to be composed entirely of igneous hyaloclastite material some proportion of clastic sedimentary rocks is likely to be present the vp vs and vp properties of the units underlying the low velocity zone are inconsistent with crystalline

numerical simulation of remote acoustic sensing of ocean temperature in the fram strait environment an important part of the general problem of the arctic climate change is the monitoring of the fram strait which lies between greenland and spitsbergen for this reason it is reasonable to apply acoustic methods which are proven to be effective in acoustic ocean thermometry acoustic tomography etc knowledge of the main peculiarities of sound signal propagation in this region is needed to estimate the feasibility of applying remote acoustic methods to this end computer simulation of sound signal propagation in the fram strait environment was performed based on oceanographic data obtained by the r v polarstern expedition the presence of stable eigenrays in fram strait environmental conditions is demonstrated typical values of acoustic signal travel time fluctuations due to environmental variations are determined and the temperature effect on the signal travel time variation is considered sensitivity estimates for measurement of the average ocean temperature across fram strait is considered in two approaches by calculating travel time changes along selected stable eigenrays and by determining the cumulative sum of the whole envelope of the signals passed along water borne paths

thermal evolution of the greenland sea gyre in 1988 1989 slice inverses of temperature and heat content from the 1988 1989 greenland sea tomography experiment and other observations including standard conductivity temperature depth stations moored thermistors surface meteorological variables and surface ice cover are combined to better understand the thermodynamics of the greenland sea gyre thermal evolution of the gyre center seems to divide naturally into the following three periods a preconditioning phase november january during which surface salinity is increased by brine rejection from ice formation and by entrainment but in which the mixed layer deepens only slowly to a depth of some 150 200 m a deep mixing phase february march during which the surface mixed layer deepens rapidly to approximately 1500 m in the gyre center purely under the influence of local surface cooling and a restratification phase during which the products of deep mixing are replaced by arctic intermediate water flowing in from the gyre edges the onset of the deep mixing phase occurs after ice formation in the gyre center stops resulting in an area of open water where large heat fluxes can occur in surrounding regions including the odden region to the south ice is still being formed to the north and west closer to the steep topography of the continental shelf the inverse results show significant variability due to advection and large temperature and heat content fluctuations with a period of about 50 days are seen

molecular fossils in coastal bitumens from southern australia signatures of precursor biota and source rock environments abstract weathered waxy crude oil and black asphaltite tar are regularly washed ashore along the coastlines of south australia and western victoria these bitumens generally strand on medium to high energy sandy beaches in west or southwest facing bays some very weathered bitumens have been discovered in holocene dune deposits up to 200 m from the present day coastline differences in the sulphur content and carbon hydrogen and sulphur isotopic compositions of the coastal bitumens suggest that they belong to at least four oil families one of which may be emanating from submarine seeps along australia s highly faulted southern continental margin the remainder appear to be flotsam carried south from s e asia possibly sumatra the waxy bitumens families 1 3 range from paraffinic to aromatic intermediate in bulk composition and contain up to 2 6 s their density 13 38 api dictates that they are near surface drifters they have low pristane phytane ratios pr ph 2 abundant 4 methyl steranes c 30 with 24 ethyl substitution and in most cases high concentrations of botryococcane this biomarker assemblage indicates accumulation of freshwater algal source material including the remains of botryococcus sp and dinoflagellates under anoxic to suboxic conditions the additional presence of 28 30 bisnorhopane dinosterane and 24 n propylcholestane among the molecular fossils in family 3 bitumens suggests derivation from a lacustrine organic facies subject to marine incursions or alternatively mixing in the reservoir of two end member lacustrine and marine oil types trace amounts of oleanane and isomeric bicadinanes in the waxy bitumens constrain the age of their source rocks late cretaceous or younger and also preclude their local derivation an indonesian origin is considered likely implying long distance transport by surface ocean currents the family 4 bitumens 5 api are bottom drifters these sulphur rich 3 6 s aromatic asphaltic crudes have molecular signatures that include pr ph 1 c 27 c 29 c 28 c 30 desmethyl steranes dinosterane dominant over 4 methyl 24 ethylcholestane an enhanced concentration of 28 30 bisnorhopane relative to hopane and the absence of 2 or 3 methylhopanes a distal anoxic marine facies of the late cretaceous belfast mudstone in the eastern otway basin or its lithostratigraphic equivalent in the duntroon basin are possible local sources of the asphaltic bitumens

acoustic travel time perturbations due to shallow water internal waves and internal tides in the barents sea polar front theory and experiment during august 1992 a combined acoustics physical oceanography experiment was performed to study both the acoustical properties and the ocean dynamics of the barents sea polar front in the region near bear island oceanographic observations from shipboard hydrography and moored sensors allowed the construction of the internal wave frequency spectrum for the area a rapidly sampled tomographic section from a 224 hz 16 hz bandwidth acoustic source to a 16 element vertical receiving array enabled the monitoring of travel time fluctuations over the internal wave frequency band to describe the measured acoustic fluctuations theoretical expressions have been developed for the travel time variances which are functions of the internal wave oceanographic field the local acoustic propagation characteristics and the acoustical system s properties both ray and mode theory expressions are generated as the experiment was performed in shallow water and both ray and mode arrivals were resolvable comparison of the

stable carbon isotope compositions of crude oils application to source depositional environments and petroleum alteration the carbon isotopic composition of the c15 saturate and aromatic hydrocarbon fractions and the gas chromatographs of the c15 saturate fraction of 339 oils were geochemically and statistically evaluated results of this study show that the average isotopic compositions of the c15 aromatic hydrocarbon fractions of oils sourced from terrigenous or marine organic matter are identical the average isotopic composition of the c15 saturate fraction of oils derived from terrigenous organic sources is slightly more negative 0 9 pmil than the average for marine oils but this difference is insufficient to be used as a reliable source indicator reports in the literature stating that marine oils are isotopically more positive than te rigenous oils and that the difference can be utilized to distinguish between the two are therefore not supported by this study the isotopic differences between oils sourced from terrigenous and marine organic matter do not manifest themselves in the range of absolute values of one oil fraction but rather in the isotopic relationship between the saturate and aromatic hydrocarbon fractions the isotopic relationship is the following oils of terrigenous organic source dgr13caro 1 12 dgr13csat 5 45 oils of marine organic source dgr13caro 1 10 dgr13csat 3 75 the difference between the two equations was evaluated statistically and a statistical parameter cv the canonical variable cv 2 53 dgr13csat 2 22 dgr13caro 11 65 was used to distinguish between marine and terrigenous oils cv values larger than 0 47 indicate predominantly a terrigenous organic source for the oil whereas cv values smaller than 0 47 indicate mostly a marine organic source thermal maturity differences in oils and isotopic variations in the source beds can cause as much as 2 pmil variations in the isotopic composition of one family of oils finally stable carbon isotopes can in some situations help correlate biodegraded oils to their nondegraded counterparts

hydrocarbon traces in the tertiary basalts of the faeroe islands abstract hydrocarbons in the form of gases oils and waxes have been observed in the basalts of the faeroe islands in the north atlantic gases and traces of oil were observed in the outflowing water of the deep lopra 1 well drilled in 1981 the hydrocarbon gas was fairly dry with stable isotopic ratios of 13c1 3 41 4 32 4 26 5 respectively typical of a thermogenic gas high temperature gas chromatography of the oil showed that it consisted mostly of c13 60 n alkanes biomarker distribution observed by gc ms indicates that the oil was derived from a mature source rock deposited in an anoxic environment this suggests that the source rock must lie beneath the known basalts waxes exhibiting bright yellow fluorescence under uv light were observed as coatings on zeolite minerals widely distributed on the faeroe islands the waxes consist predominantly of higher n alkanes shown by htgc the fluorescence indicates the presence of aromatic compounds biomarker distribution indicated that the waxes were derived at least in part from a source rock containing some terrestrial organic matter astestified by the low amounts of oleanane present the waxes were probably deposited from traces of oil present in deeply circulating waters in fractures within the basalts coals which had been suspected to generate some of the hydrocarbons observed in the faeroese basalts were also examined vitrinite values of ro 0 5 as well as gc ms analyses of the suduroy coal extracts showed that these coals are immature and have not generated significant hydrocarbons

improved understanding of mixed oil in nigeria based on pyrolysis of asphaltenes abstract crude oil from reservoirs in the onshore niger delta is a mixture of low and high maturity charge aromatic biomarkers in these oils such as alkylphenanthrenes and alkylnaphthalenes show relatively high thermal maturity whereas the saturated sterane and hopane biomarkers indicate lower maturity close to the peak of the oil window the high predicted maturity of the crude oils based on alkylphenanthrene and alkylnaphthalene indices is probably caused by mixing of high maturity condensate with less mature black oil this correlates with the gas washing phenomenon of studied nigerian oils caused by migrating condensate stream the results of our study indicate that asphaltenes can be used to infer the organofacies of the low maturity petroleum charge in mixed crude oils compositional characteristics of the asphaltene pyrolysates indicate an origin of the related oils from type ii iii or type iii source rock kerogen the n alkyl chain length distributions of the asphaltene pyrolysates predict source rocks that generated high wax paraffinic naphthenic aromatic oils or paraffinic oils the n alkyl chain length of asphaltene pyrolysates changes in proportion to oxicity and the relative input of terrigenous organic matter to the source rock

understanding the offshore flood basalt sequence using onshore volcanic facies analogues an example from the faroe shetland basin flood basalts in associated volcanic rifted margins such as the north atlantic igneous province have a significant component of lavas which are preserved in the present day in an offshore setting a close inspection of the internal facies architecture of flood basalts onshore provides a framework to interpret the offshore sequences imaged by remote techniques such as reflection seismology a geological interpretation of the offshore lava sequences in the faroe shetland basin using constraints from onshore analogues such as the faroe islands allows for the identification of a series of lava sequences which have characteristic properties so that they can be grouped these are tabular simple flows compound braided flows and sub aqueously deposited hyaloclastite facies the succession of volcanic rocks calculated in this study has a maximum thickness in excess of 6800 m down to the top of the sub volcanic sediments the offshore volcanic succession has a thickness of about 2700 m where it can be clearly identified across much of the area with a further 2700 m or more of volcanic rock estimated from the combined gravity and seismic modelling to the north and west of the region a large palaeo waterbody is identified on the basis of a hyaloclastite front apron consisting of a series of clinoforms prograding towards the eastern part of the basin this body was 500 m deep must have been present at the onset of volcanism into this region and parts of the water body would have been present during the continued stages of volcanism as indicated by the distribution of the hyaloclastite apron

postseismic deformation due to the mw 6 0 2004 parkfield earthquake stress driven creep on a fault with spatially variable rate and state friction parameters 1 we investigate the coseismic and postseismic deformation due to the m w 6 0 2004 parkfield california earthquake we produce coseismic and postseismic slip models by inverting data from an array of 14 continuous gps stations from the scign network kinematic inversions of postseismic gps data over a time period of 3 years show that afterslip occurred in areas of low seismicity and low coseismic slip predominantly at a depth of 5 km inversions suggest that coseismic stress increases were relaxed by predominantly aseismic afterslip on a fault plane the kinetics of afterslip is consistent with a velocity strengthening friction generalized to include the case of infinitesimal velocities we performed simulations of stress driven creep using a numerical model that evaluates the time dependent deformation due to coseismic stress changes in a viscoelastoplastic half space starting with a coseismic slip distribution we compute the time dependent evolution of afterslip on a fault plane and the associated displacements at the gps stations data are best explained by a rate strengthening model with frictional parameter a b 7 x 10 3 at a high end of values observed in laboratory experiments we also find that the geodetic moment due to creep is a factor of 100 greater than the cumulative seismic moment of aftershocks the rate of aftershocks in the top 10 km of the seismogenic zone mirrors the kinetics of afterslip suggesting that postearthquake seismicity is governed by loading from the nearby aseismic creep the san andreas fault around parkfield is deduced to have large along strike variations in rate and state frictional properties velocity strengthening areas may be responsible for the separation of the coseismic slip in two distinct asperities and for the ongoing aseismic creep occurring between the velocity weakening patches after the 2004 rupture

oleanane parameter verification by quantitative study of the biomarker occurrence in sediments of the niger delta abstract the variation of the absolute concentration of oleananes in three selevted sedimentary columns of the tertiary niger delta is paralleled by the corresponding oleanane parameter op profile thereby confirming that the latter can be utilized for estimating the relative contribution of terrigenous organic matter it is shown that op features a dynamic range especially at the oil generative window ogw and can precisely delimit the top of the ogw which for the niger delta is shown to coincide approximately with the 80 c isotherm and ro 0 55 this study provides the first direct evidence of the inadequacy of vitrinite reflectance as a maturity parameter for type iii kerogen furthermore based on the new findings an alternative model for oleanene oleanane interconversions in the geosphere is proposed

coseismic and postseismic deformation of the 2016 mw 6 2 lampa earthquake southern peru constrained by interferometric synthetic aperture radar

structure and kinematic evolution of the duke river fault southwestern yukon in southwest yukon the boundary between the alexander terrane and wrangellia corresponds with the duke river fault in this paper we report on observations of the duke river fault from four localities in southwest yukon and provide new constraints on 1 permian regional metamorphism within the alexander terrane 2 cretaceous ductile deformation along the duke river fault and 3 post miocene brittle deformation along the fault within these areas the duke river fault juxtaposes imbricated pervasively foliated and folded greenschist facies rocks of the alexander terrane southwest of the fault against sub greenschist facies less deformed rocks of wrangellia multiple lines of evidence from this region indicate the alexander terrane has been juxtaposed against wrangellia along a southwest dipping thrust fault 40ar 39ar dates from muscovite which grew during faulting or have been reset by motion along the duke river fault range from 79 to 105 ma suggesting that ductile movement along the fault i

chemical molecular and isotopic differentiation of organic facies in the tertiary lacustrine duaringa oil shale deposit queensland australia abstract total organic matter extractable organic matter bitumen and pyrolysates released on low temperature sealed tube pyrolysis of kerogen were analysed chemically and isotopically based on bulk bitumen and biomarker parameters the sediments are immature to a depth of approx 1300 m within the terrestrial and lacustrine depositional environments of the tertiary duaringa basin various organic facies have been classified according to inorganic input and maceral abundances of organic matter derived from land plant and algal sources the latter derived mainly from pediastrum and with a varying botryococcus content the lacustrine upper lamosite is chemically and isotopically distinct from the lower lamosite due to a changing algal community relative contributions from allochthonous land plants and for the lower lamosite a slightly more saline and restricted lake environment the lower lamosite is associated with the highest concentrations of c 28 c 30 4 methylsteranes and 13 c depletion in toc in the upper lamosite there is a strong positive correlation between botryococcus content and 13 c enrichment the organically lean claystones have sources nearly identical to the lamosites but the organic matter is diluted due to rapid influx of siliciclastics the terrestrial facies the cannel coal and carbonaceous shales are mainly distinguished from the lacustrine facies by higher relative proportions of c 29 steranes c 30 4 methylsteranes and 13 c values for the pyrolysed hydrocarbons intermediate between the two lamosite facies the carbonaceous oil shale has a composite geochemical signature intermediate between the two end members lamosite and cannel coal oleanane and ring a degraded triterpanes derived from lupane arborane and oleanane skeletons are distributed throughout all organic facies representing both autochthonous and allochthonous higher plant inputs higher concentrations of oleanane and des a lupane are associated with the terrestrial facies hopanes dominate over steranes in all organic facies and their concentration ranges are independent of facies for the lamosites the aliphatic biopolymer algaenan is implicated as the dominant source for n alkanes from analysis of their yields homologue abundances and individual 13 c values in the terrestrial facies resinites are paraffinic and are a major source for the n alkanes released on pyrolysis compound specific analysis of extractable and pyrolysate hydrocarbons allowed deconvolution of different source inputs to free lipids and kerogen for the lamosites low molecular weight n alkanes in the bitumen are derived mainly from a pediastrum source while botryococcus is associated with waxy n alkanes however the situation is reversed in the kerogen pediastrum algeanan has a longer average alkyl chain length than botryococcus algaenan the magnitude of the isotopic differences between single n alkanes released at different temperatures is useful in determining multiplicity of sources

organic geochemical study of the w oil gas field in the yugoslav part of the pannonian basin the naphthenic crude oil from the w oil gas field differs from almost all other paraffinic base oils discovered until now in the yugoslav part of the pannonian basin in order to explain this difference some geological and organic geochemical investigations were carried out on the basis of the bulk and biomarker parameters determined in oil samples taken from 13 producing wells located at different parts of the field it is concluded that the crude oil throughout the field has an almost uniform composition however some differences in alkane content due to biodegradation and or water washing were found in the northeast part of the field where a tilted oil water layers shows an active hydrodynamism and where the temperatures are the lowest and pressure gradients the highest the isoprenoids pristane and phytane were detected in trace amounts indicating the most intensive biodegradation in the central part where a hydrocarbon accumulation exists in a miocene reservoir somewhat lower biodegradation was observed the crude oil from this field has probably a mixed terrestrial marine origin and is derived from argillaceous source rocks sedimented in marine delta or brackish lakes specific maturation parameters confirmed that the w crude oil has reached a quite uniform and significant thermal maturation considering maturation parameters such as ratios c30 moretane hopane and c29 20s 20s 20r steranes as well as the presence of oleanane it could be proposed that the w oil originates from a pre tertiary source rock at least an upper cretaceous one unlike most pannonian basin oils which are tertiary in age

numerical simulation of the transverse current monitoring in the fram strait the numerical simulation of transverse current monitoring in the fram strait environment is performed using horizontal refraction modal tomography hrmt the simplified west spitsbergen current profile is constructed in the framework of geostrophic approach and calculation of the modal phase difference between signals arriving along the two paths of acoustical interferometer due to horizontal refraction is made for the sound signal frequencies 100 200 hz and different sound source depth it was demonstrated that the measurable modal phase difference in a range of 80 160 can be expected for an averaged current velocity in the strait cross section of 0 3 m s at higher frequency of the sound signal the sensitivity of the hrmt increases but the space coherency decreases so the optimal frequency has to be chosen the strong mode coupling effect presented in such a complex environment was apparently weakened by using the signals propagating along the closed paths