sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

block models of crustal motion in southern california constrained by gps measurements 1 we estimate slip rates on major active faults in southern california using a block model constrained by global positioning system measurements of interseismic deformation the block model includes the effects of block rotation and elastic strain accumulation consistent with a simple model of the earthquake cycle our estimates of the right lateral strike slip rate on the san andreas fault vary by at least a factor of 5 from a high of 35 9 0 5 mm yr in the carrizo plain to a low of 5 1 1 5 mm yr through the san bernadino segment shortening across the puente hills thrust and left lateral slip on the raymond hill fault are consistent with both thickening and escape tectonics in the los angeles basin discrepancies between geodetic and geologic slip rate estimates along the san andreas and san jacinto faults as well as in the eastern california shear zone may be explained by a temporal change in fault system behavior we find no substantial evidence for long term postseismic relaxation and infer that the viscosity of the lower crust upper mantle may be relatively high 1019 pa s

spatial and temporal deformation along the northern san jacinto fault southern california implications for slip rates the san timoteo badlands is an area of uplift and erosional dissection that has formed as a result of late quaternary uplift along a restraining bend in the san jacinto fault of the san andreas fault system in southern california this bend currently is located in a region where late quaternary deposits and associated surfaces have formed in lower san timoteo canyon we have used morphometric analysis of these surfaces in conjunction with computer modeling of deformational patterns along the san jacinto fault to reconstruct spatial and temporal variations in uplift along the bend morphometric techniques used include envelope subenvelope map ping a gradient length index along channels and denudation values age control is determined using a combination of thermoluminescence tl and near infrared op tical simulation luminescence dating irosl and correlation of soil development indices these approaches are combined with an elastic half space model used to determine the deformation associated with the fault bend the region of modeled uplift has a similar distribution as that determined by morphometric techniques luminescence dates and soil correlation age estimates generally agree based on soil development surfaces within the study area were stabilized at approximately 300 700 ka for q3 43 67 ka for q2 and 27 5 67 ka for q1 luminescence ages both tl and irosl for the formation of the younger two surfaces are 58 to 94 ka for q2 and 37 to 62 ka for q1 ages reported to 1r uncertainty periods of uplift were determined for the surfaces in the study area resulting in approximate uplift rates of 0 34 to 0 84 m ka for the past 100 ka and 0 13 to 1 00 m ka for the past 66 ka comparison of these rates of uplift to those generated by the model support a higher rate of lateral slip along the san jacinto fault than commonly assumed greater than 20 mm yr as compared to 8 12 mm yr commonly cited this higher slip rate supports the proposal that a greater amount of slip has transferred from the san andreas fault to the san jacinto fault than generally held the san jacinto fault may have accommodated a significant portion of the plate boundary slip during the past 100 ka

insar analysis of natural recharge to define structure of a ground water basin san bernardino california using interferometric synthetic aperture radar insar analysis of ers 1 and ers 2 images we detect several centimeters of uplift during the first half of 1993 in two areas of the san bernardino ground water basin of southern california this uplift correlates with unusually high runoff from the surrounding mountains and increased ground water levels in nearby wells the deformation of the land surface identifies the location of faults that restrict ground water flow maps the location of recharge and suggests the areal distribution of fine grained aquifer materials our preliminary results demonstrate that naturally occurring runoff and resultant recharge can be used with interferometric deformation mapping to help define the structure and important hydrogeologic features of a ground water basin this approach may be particularly useful in investigations of remote areas with scant ground based hydrogeologic data

insar reveals coastal subsidence in the pearl river delta china summary the pearl river delta prd is one of the most important economic regions with the highest population densities in china with its dramatic increasing population and economy hazards associated with land subsidence frequently occur here that amplify the negative effect of sea level rise however land subsidence has not been regularly measured in this region here we use interferometric synthetic aperture radar insar to investigate the rate and extent of land subsidence in the prd region assuming purely vertical displacements multi track interferograms from different viewing geometries are combined to estimate the linear rate map and time series at a higher resolution in time than is possible with a single track the results show apparent subsidence along the coastal region of shenzhen associated with rapid urban development in recent years the average subsidence rate within 500 m of the coast is about 2 5 mm yr 1 and the maximum is up to about 6 mm yr 1 with respect to the central part of the city much of the land surface in the prd is less than 2 m above mean sea level high precision geodetic measurements throughout the prd region are therefore critical for conducting risk assessments considering the rate of about 2 3 mm yr 1 of current global sea level rise

holocene rate of slip and tentative recurrence interval for large earthquakes on the san andreas fault cajon pass southern california abstract detailed mapping of the san andreas fault zone where it crosses cajon creek southern california has revealed a number of late quaternary deposits and geomorphological features offset by the fault radiocarbon dates from alluvial and swamp deposits provide a detailed chronology with which to characterize the activity of the san andreas fault four independent determinations of the slip rate on the san andreas fault yield an average rate of 24 5 3 5 mm yr for the past 14 400 years the similarity of the four values which span different intervals of time from 5900 to 14 400 years ago suggest that the slip rate has been constant during this period the slip rate confirms that the san andreas fault is accumulating slip faster than any other fault in the plate boundary throughout california also the sum of the slip rates on the san andreas 24 5 mm yr and the san jacinto 10 mm yr faults south of their junction is the same as the san andreas north of their junction 35 mm yr an excavation provided evidence for at least two and up to four earthquakes that caused rupture on the fault between 1290 and 1805 a d and tentative evidence for six earthquakes in about the last 1000 years both lines of evidence imply an average recurrence interval for large earthquakes of about 1 to 2 centuries combined with the historic record this investigation indicates that the last major earthquake at cajon creek was probably at the beginning or middle of the 18th century while the record at cajon creek may suggest that the next major earthquake on the san andreas fault is overdue the data can be interpreted to indicate that the recurrence interval for earthquakes on the san andreas south of the 1857 rupture is 3 to 4 centuries and that the anticipated event should not be expected until the next century

high quality insar data linked to seasonal change in hydraulic head for an agricultural area in the san luis valley colorado in the san luis valley slv colorado legislation passed in 2004 requires that hydraulic head levels in the confined aquifer system stay within the range experienced in the years 1978 2000 while some measurements of hydraulic head exist greater spatial and temporal sampling would be very valuable in understanding the behavior of the system interferometric synthetic aperture radar insar data provide fine spatial resolution measurements of earth surface deformation which can be related to hydraulic head change in the confined aquifer system however change in cm scale crop structure with time leads to signal decorrelation resulting in low quality data here we apply small baseline subset sbas analysis to insar data collected from 1992 to 2001 we are able to show high levels of correlation denoting high quality data in areas between the center pivot irrigation circles where the lack of water results in little surface vegetation at three well locations we see a seasonal variation in the insar data that mimics the hydraulic head data we use measured values of the elastic skeletal storage coefficient to estimate hydraulic head from the insar data in general the magnitude of estimated and measured head agree to within the calculated error however the errors are unacceptably large due to both errors in the insar data and uncertainty in the measured value of the elastic skeletal storage coefficient we conclude that insar is capturing the seasonal head variation but that further research is required to obtain accurate hydraulic head estimates from the insar deformation measurements

pyrite framboid evidence for oxygen poor deposition during the permian triassic crisis in kashmir abstract the khunamuh formation of the guryul ravine section in kashmir provides one of the most detailed deep water records of the end permian mass extinction in perigondwanan palaeolatitudes examination of pyrite framboid size distributions and sediment microfabric reveals a distinct change in the uppermost permian strata from nonlaminated pyrite free silty mudstones to finely laminated silty shales rich in framboidal pyrite around 1 m above the base of the formation the size frequency distribution of the framboids is identical to populations from severely oxygen restricted modern depositional environments this change to dysoxic benthic conditions coincides with the rapid demise of diverse permian brachiopod and bryozoan assemblages thus the link between extinction and anoxia is clearly seen at guryul ravine and it provides an interesting contrast to other perigondwanan sections developed in shallower water where both the onset of anoxia and the extinction occurred somewhat later in the earliest triassic

formation processes of framboidal pyrite abstract pyrite framboid formation may be the result of four consecutive processes 1 nucleation and growth of initial iron monosulfide microcrystals 2 reaction of the microcrystals to greigite fe 3 s 4 3 aggregation of uniformly sized greigite microcrystals i e framboid growth and 4 replacement of greigite framboids by pyrite the uniform morphology uniform size range and ordering of the microcrystals in individual framboids as well as the range of observed framboid structures from irregular aggregates to densely packed spherical aggregates and polyframboids are consequences of these processes using dlvo theory derjaguin landau verwey and overbeek we have evaluated the stability of colloidal iron monosulfide suspensions with ionic strengths typical of marine and lacustrine waters in addition to van der waals attractive and double layer repulsive forces a term is included to account for the ferrimagnetic properties of greigite numerical models predict that magnetically saturated greigite particles 0 1 m in diameter will rapidly aggregate in either marine or fresh water the aggregation model is in agreement with the sequence of greigite formation followed by pyrite framboid formation established in a previous experimental study sweeney and kaplan 1973 and is consistent with the occurrence of framboids composed of other magnetic minerals e g greigite magnetite and magnesioferrite based on the temperature dependent magnetic properties of greigite and aging experiments in hydrothermal solutions this mechanism for framboid formation via precursor greigite could operate to temperatures of 200 c consistent with the occasional occurrence of pyrite framboids in the paragenesis of metalliferous ore deposits

variations in pyrite texture sulfur isotope composition and iron systematics in the black sea evidence for late pleistocene to holocene excursions of the o2 h2s redox transition time dependent variations in the physicochemical properties of pyrite were investigated in four sediment cores from the black sea in the laminated deep basin sediments of unit i and unit ii 86 of pyrite particles are present as fine grained framboidal aggregates in these sediments the dominance of pyrite framboids with a narrow size distribution and maximum size 18 m is evidence of syngenetic water column pyrite formation subjacent to the o2 h2s boundary sediments from the basin margin collected below the impingement of the o2 h2s boundary contain an increased proportion of fine grained euhedral grains of pyrite relative to framboidal aggregates suggesting increased additions of diagenetic pyrite below the sediment water interface the more efficient reduction and sulfidation of iron in the water column of the central region of the basin implies a more reactive source of iron there compared to the basin margins and is tied to increasing pyrite as framboids and greater degrees of pyritization dop in the basin center relative to the basin margins an evaluation of fe s c relations indicates that pyrite formation was limited by sulfate availability during deposition of the oldest lacustrine sediments of unit iii c limited for upper unit iii due to the input of sulfate rich mediterranean seawater and fe limited in the laminated organic carbon rich sediments of units i and ii these changes in pyrite limiting factors occurred within 4 m of compacted burial representing 15 ka sediment fabric and framboid size distributions at a shallow basin margin site suggest that during two extended periods of unit ii deposition the o2 h2s transition retreated to depths below 200 m however during these same intervals the 34s of pyrite remains uniform compared to overlying and underlying laminated sediments implying that this chemical signature may not be uniquely tied to the position of the o2 h2s boundary relative to the sediment water interface but rather is likely related to biogeochemical processes

oceanic water redox conditions of the region between tethys and panthalassa during the late early triassic abstract fossil evidence of a complex food chain in the marine ecosystem after the end permian mass extinction epme event has been reported from the osawa formation which consists of upper olenekian spathian shallow marine mudstone dominant strata in the south kitakami belt in northeast japan this sedimentary sequence offers an important material that records the paleoenvironment of the oceanic region between the eastern tethys and panthalassa this paper reports detailed records of the oceanic environment from two sections of the osawa formation focusing on the redox condition parallel undisturbed laminae suggesting limited benthic activity are prominent in the middle to upper parts of the osawa formation while disturbance of laminae by burrows occurs in the lower and uppermost parts suggesting active benthic activity in an oxygen rich depositional environment the amount of pyrites euhedral pyrite pyrite framboids and pyrite polyframboids increases in the well laminated mudstones a relatively broad size distribution of pyrite framboids indicates that these mudstones were deposited under dysoxic conditions and suggest that the water column was not sulfidic redox sensitive elements such as mn v and u show values close to the average values of the upper continental crust throughout the osawa formation mo is moderately enriched in the well laminated and pyrite abundant mudstone horizons although the degree of enrichment is lower than known examples of modern sulfidic basins these data suggest that the condition of the bottom water in this oceanic region during the spathian varied between oxic and dysoxic weakly oxygenated and was never sulfidic such an oceanic environment characterized by mildly reducing bottom water and oxic water column appears to have been the settings for the recovery and establishment of the early triassic marine ecosystem characterized by diverse nektonic motile animals and limited diversity of benthic in motile animals

san andreas fault geometry through the san gorgonio pass california three dimensional numerical models are needed to investigate the role of nonvertical strike slip fault segments on the deformation within restraining bends numerical models simulate geologic deformation of two alternative three dimensional present day configurations for the san andreas fault through the restraining bend within the san gorgonio pass region sgpr in southern california both models produce decreasing strike slip rates southward along the san bernardino strand of the san andreas fault similar to geologic data the north dipping san andreas fault model better matches the available strike slip data as well as the geologic uplift data for the southern san bernardino mountains than the vertical san andreas fault model we conclude that a north dipping fault configuration is preferred for models of the san andreas fault in the sgpr the complexity of the active fault geometry at the sgpr promotes the transfer of strike slip from the san andreas fault to the nearby but unconnected san jacinto fault slip rates and uplift patterns are sensitive to fault geometry within strike slip restraining bends

reconstruction of redox conditions during deposition of organic rich shales of the upper triassic yanchang formation ordos basin china the concentration and distribution of organic matter phosphate nodules and framboidal pyrite preserved in shales are controlled by organic matter decomposition and the cycles of phosphorus sulfur and iron which in turn are controlled by bottom water redox conditions the organic rich shale in the 7th member of the upper triassic yanchang formation ch7 contains high organic carbon concentrations and abundant phosphate nodules and pyrite framboids providing an opportunity to better understand the redox conditions at the time of deposition framboidal pyrite in the ch7 organic rich shales are composed of octahedral pyritohedral and spherulitic microcrystals with uniform crystal size sem photographs and statistical data suggest that pyrite framboids have large mean diameters 10 0 to 18 1 m and standard deviations 2 8 to 5 9 m this may indicate that the organic rich shale was deposited under oxic suboxic bottom water conditions the corg p ratios of the organic rich shale exhibit considerable variation ranging from 7 2 to 216 but the majority of them 83 2 belong to the lower intermediate range 130 suggesting that the redox conditions were predominantly oxic suboxic and intermittently anoxic the corg p ratios also show periodic vertical variation which suggests that redox conditions fluctuated between oxic suboxic and anoxic additional support for the trends based on corg p ratios is provided by dopt values which show similar vertical variation and redox patterns all evidence shows that the redox conditions during deposition of the ch7 organic rich shale was predominantly oxic suboxic accompanied by intermittent anoxic environments the result of this study will be helpful in better understanding the formation mechanism of the ch7 organic rich shale

palaeoceanographic redox environments for the lower cambrian hetang formation in south china evidence from pyrite framboids redox sensitive trace elements and sponge biota occurrence abstract the lower cambrian hetang formation a black shale sequence contains a stone coal a flammable organic rich mudstone unit abundant pyrite framboids occur in this unit with the average mean sizes falling in a narrow range from 4 6 to 5 4 m and the maximum diameters being around 10 m the size distribution pattern of the pyrite framboids indicates a euxinic depositional environment the redox sensitive trace metals of the stone coal samples reveal a large enrichment of mo 10 180 times v 4 40 times u 10 60 times and ni 2 20 times compared to the average upper continental crust value consistent with an anoxic environment for their deposition the redox sensitive element ratios th u v v ni v cr indicate that the depositional environment for the lower part of the stone coal unit was the most anoxic and euxinic in contrast a sponge biota including eleven species of demosponges and hexactinellids and two undetermined forms indicate an oxic or dysoxic environment to reconcile these two facts we propose that although an anoxic euxinic environment predominated during the deposition of the lower cambrian hetang formation black shales occasional currents may also have brought free oxygen to the bottom water column to allow the growth of the sponges on the sea floor

extended 3β methylhopanes up to c45 in source rocks from the upper cretaceous qingshankou formation songliao basin northeast china abstract 3 methylhopanes methylated at the c 3 position of the a ring have been detected ubiquitously in sedimentary rocks with carbon numbers of c28 and c30 c36 these compounds have been attributed to aerobic methanotrophs due to their strongly 13c depleted compositions here we report 3 methylhopanes with carbon numbers up to c45 in source rocks from the first member of the upper cretaceous qingshankou formation songliao basin northeast china the extended homologues up to c45 might be derived from long chain alkyl bacteriohopanetetrols by consecutive enzymatic additions of a c5 sugar extremely 13c depleted compositions combined with a high 3 methylhopane index suggest an intense ch4 cycle induced by blooms of aerobic methanotrophs in the songliao paleo lake

rock magnetic records of the qingshankou formation of sk 1 south borehole in songliao basin northeast china and their paleoclimate implications abstract the south borehole sk 1s of the china cretaceous continental scientific drilling project songke 1 penetrated the late cretaceous lacustrine sediments in the central depression of the songliao basin northeast china in order to reveal the terrestrial records of the cretaceous climate changes high resolution rock magnetic records were obtained on the qingshankou formation k 2 qn of sk 1s the results indicate that detrital magnetite is the main remanence carrier of the k 2 qn formation while both magnetite and paramagnetic minerals including clay minerals and pyrite dominantly contribute to magnetic susceptibility although reductive diagenesis may have more or less effect on the magnetic signals of the k 2 qn formation they recorded ancient lake level changes well resulting both from the tectonic development of the basin and from the milankovitch astronomical paleoclimatic changes the first order vertical trends of the rock magnetic records were controlled by the shallowing upwards of the lake level caused by the tectonic uplift of the basin the short term variations of the rock magnetic records were controlled by the lake level periodical drift caused by the fluctuations of the rainfall of the catchment area of the basin which were controlled by astronomical orbital forcing in addition the magnetic records also distinguished two most anoxic periods during the lacustrine anoxic event 1 lae1 the sections of 1758 1761 m and 1769 1771 5 m which may suggest the two most active periods of surface productivity of the lake

focal spot imaging based on zero lag cross correlation amplitude fields application to dense array data at the san jacinto fault zone we image the subsurface below a dense seismic array straddling the clark branch of the san jacinto fault zone in southern california the analysis is based on focal spots of surface waves associated with the zero lag amplitudes of noise cross correlations computed between all stations of the dense array local medium properties are inferred from the spatially variable focal spot size and shape based on the first zero crossing of amplitude versus distance distributions the method provides simultaneous estimates of wave speed apparent attenuation and anisotropy without solving a tomographic inverse problem the obtained images of the frequency dependent seismic velocity distributions are consistent with independent estimates from a far field rayleigh wave tomography we observe an anticorrelation between our apparent attenuation coefficient and seismic velocity and a fault parallel alignment of fast propagation directions with greater structural complexity to the southwest of the fault the results imply a complex fault zone structure including a waveguide to the northeast of the fault that is continuous across the observed depth range and a low velocity structure to the southwest associated with a shallow sedimentary basin

enhanced framboidal pyrite formation related to anaerobic oxidation of methane in the sulfate methane transition zone of the northern south china sea abstract many studies have confirmed that size distributions of framboidal pyrite can be an effective indicator of bottom water redox conditions in modern as well as ancient sedimentary environments however one environment in which production of framboidal pyrite has not been sufficiently studied to date is the sulfate methane transition zone smtz in which anaerobic oxidation of methane aom is coupled with microbial sulfate reduction msr to enhance iron sulfide mineral precipitation e g fes2 fes and fe3s4 here we document for the first time size distributions for pyrite framboids from the smtz based on data from two sites in the methane hydrate bearing region of the northern south china sea on the basis of framboid size pyrite concentration and sulfur isotope data we propose new insights into the formation process of authigenic pyrite framboids within the smtz we conclude that 1 enhanced anaerobic oxidation of methane aom not only plays a dominant role in the accumulation of 34s enriched pyrite but also is responsible for formation of highly variable and sometimes exceptionally large pyrite framboids in the smtz 2 most framboids occur in framboid clusters which commonly exhibit rod like shapes secondary overgrowths heavier 34s values and unusual size distributions e g mean size 20 m and standard deviation 3 0 m in the smtz 3 pyrite framboids formed in the smtz which have characteristics different from those formed in the sulfate reduction zone srz do not comment on redox conditions of the overlying water column and 4 framboid occurrences with similar characteristics in ancient marine deposits may be considered indicators of enhanced aom and mark the former position of the smtz in the paleo marine system in addition significant quantities of elemental sulfur were observed in the smtz possibly related to anaerobic oxidation of hydrogen sulfide and fluctuations of the smtz

detection of aquifer system compaction and land subsidence using interferometric synthetic aperture radar antelope valley mojave desert california interferometric synthetic aperture radar insar has great potential to detect and quantify land subsidence caused by aquifer system compaction insar maps with high spatial detail and resolution of range displacement 10 mm in change of land surface elevation were developed for a groundwater basin 103 km2 in antelope valley california using radar data collected from the ers 1 satellite these data allow comprehensive comparison between recent 1993 1995 subsidence patterns and those detected historically 1926 1992 by more traditional methods the changed subsidence patterns are generally compatible with recent shifts in land and water use the insar detected patterns are generally consistent with predictions based on a coupled model of groundwater flow and aquifer system compaction the minor inconsistencies may reflect our imperfect knowledge of the distribution and properties of compressible sediments when used in conjunction with coincident measurements of groundwater levels and other geologic information insar data may be useful for constraining parameter estimates in simulations of aquifer system compaction

deciphering vertical deformation and poroelastic parameters in a tectonically active fault bound aquifer using insar and well level data san bernardino basin california summary using insar and hydrogeologic time series spanning 1995 to 2000 we characterize the elastic storage and surface deformation in the vicinity of the san bernardino basin california the region encompasses a complex major aquifer located at the junction of the san andreas and san jacinto faults that supplies groundwater to over 600 000 people we remove the elastic vertical surface displacement associated with changes in groundwater levels from the insar time series by a least squares inversion our method estimates a poroelastic ratio at 60 well sites which we normalize by basin depth allowing for comparison of the elastic response of the aquifer skeleton from site to site our method also estimates residual vertical displacement rates at each well site surface displacement not explained by observed trends in groundwater levels residual vertical displacement rates reveal patterns of subsidence and uplift across the basin over the 5 yr period from 1995 to 2000 in a narrow zone of observed residual subsidence near the san jacinto fault where many normalized poroelastic ratios trend higher than expected we find permanent compaction of clay rich strata to be the most likely explanation for 0 5 2 0 mm yr 1 of residual subsidence this permanent compaction is likely a result of delayed compaction due to previous overdraft conditions and or a result of the installation of deep production wells during the span of the insar time series observations of localized subsidence within stepovers of the san jacinto fault zone and relative uplift at the range fronts are consistent with current basin development models however interseismic strain modelling of the regional faults does not reproduce the surface displacement pattern or magnitude of these observations

the formation of carbonate cements in the forth and balmoral fields northern north sea a case for biodegradation carbonate cementation and oil leakage during early burial

sulfide mineral chemistry investigation of sediment hosted stratiform copper deposits nahand ivand area nw iran abstract copper mineralization in nahand ivand area nw iran appears as disseminated copper sulfides along a redox boundary between gray sandstone and microconglomerate and hematitic sandstones siltstones and shaly marl geochemical analyses of the nahand ivand deposits show as much 35 wt cu and 730 ppm ag in the gray sandstone electron probe micro analysis epma was used to determine the mineralogical composition and distribution patterns of copper and silver bearing phases mainly in pyrite and cu bearing sulfides the epma data were essential for evaluating the distribution and partitioning of potential economically valuable components between co existing minerals furthermore they contribute to a better understanding of the genesis of the nahand ivand copper deposits and will guide further exploration in the region the epma results from different types of pyrite reveal cu contents as high as 0 32 wt 1 10 wt and 2 88 wt for framboidal pyrite pyi overgrowths on framboidal pyrite pyii and diagenetic pyrite pyiii respectively this successive increase of copper from pyi to pyiii is attributed to a continuous supply of copper that replaces framboidal pyrite in turn by the more copper rich digenetic pyrite because of hydrothermal overprinting pyrite has been replaced by djurleite roxbyite and other nonstoichiometric cu s minerals that include covellite the epma study indicates that covellite contains significant concentrations of ag locally 1 wt in contrast only trace amounts of silver have been detected in pyrite and other copper sulfides indicating that covellite is the major ag carrier in the ore according to textural relationships such open space filling impregnation and replacement textures and the epma results later stage copper bearing fluids were responsible for the silver enrichment in the nahand ivand deposits

inverse modeling of interbed storage parameters using land subsidence observations antelope valley california 1 we use land subsidence observations from repeatedly surveyed benchmarks and interferometric synthetic aperture radar insar in antelope valley california to estimate spatially varying compaction time constants and inelastic specific skeletal storage coefficients s kv in a previously calibrated regional groundwater flow and subsidence model the observed subsidence patterns reflect both the spatial distribution of head declines and the spatially variable inelastic skeletal storage coefficient using the nonlinear parameter estimation program ucode we estimate compaction time constants between 3 8 and 285 years the s kv values are estimated by linear estimation and range from 0 to almost 0 09 we find that subsidence observations over long time periods are necessary to constrain estimates of the large compaction time constants in antelope valley the insar data used in this study cover only a three year period limiting their usefulness in constraining these time constants this problem will be alleviated as more sar data become available in the future or where time constants are small by incorporating the resulting parameter estimates in the previously calibrated regional model of groundwater flow and land subsidence we can significantly improve the agreement between simulated and observed land subsidence both in terms of magnitude and spatial extent the sum of weighted squared subsidence residuals a common measure of model fit was reduced by 73 with respect to the original model however the ability of the model to adequately reproduce the subsidence observed over only a few years is impaired by the fact that the simulated hydraulic heads over small time periods are often not representative of the actual aquifer hydraulic heads errors in the simulated hydraulic aquifer heads constitute the primary limitation of the approach presented here

estimating temporal changes in hydraulic head using insar data in the san luis valley colorado the sustainability of the confined aquifer system in the san luis valley colorado is of utmost importance to the valley s agricultural economy there is a dearth of hydraulic head measurements in the confined aquifer to which the current groundwater flow model can be calibrated here we investigate the extent to which spatially and temporally dense measurements of deformation from interferometric synthetic aperture radar insar data can be used to fill in spatial and temporal gaps in the head data set by calibrating the insar data with head at the monitoring well locations we conduct this calibration at 11 wells where we expect sufficient deformation for reliable insar measurement given the accepted level of uncertainty 1 cm in the san luis valley crop growth degrades the quality of the insar signal which means that the high quality deformation data may not be collocated with the wells we use kriging to estimate the deformation directly at the well locations we find that the calibration is valid at three well locations where the seasonal magnitude of the deformation is much larger than the uncertainty of the insar measurement at these well locations we predict head prior to and within the temporal sampling window of the head measurements we find that 59 of the insar predicted hydraulic head values agree with the measured values within the uncertainty of the data given our success in extending the hydraulic head data temporally the next step in our research is to use insar data to interpolate spatially between head measurements

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

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

time dependent land uplift and subsidence in the santa clara valley california from a large interferometric synthetic aperture radar data set 1 we invert 115 differential interferograms derived from 47 synthetic aperture radar sar scenes for a time dependent deformation signal in the santa clara valley california the time dependent deformation is calculated by performing a linear inversion that solves for the incremental range change between sar scene acquisitions a nonlinear range change signal is extracted from the ers insar data without imposing a model of the expected deformation in the santa clara valley cumulative land uplift is observed during the period from 1992 to 2000 with a maximum uplift of 41 18 mm centered north of sunnyvale uplift is also observed east of san jose seasonal uplift and subsidence dominate west of the silver creek fault near san jose with a maximum peak to trough amplitude of 35 mm the pattern of seasonal versus long term uplift provides constraints on the spatial and temporal characteristics of water bearing units within the aquifer the silver creek fault partitions the uplift behavior of the basin suggesting that it acts as a hydrologic barrier to groundwater flow while no tectonic creep is observed along the fault the development of a low permeability barrier that bisects the alluvium suggests that the fault has been active since the deposition of quaternary units

pyrite framboid size distribution as a record for relative variations in sedimentation rate an example on the toarcian oceanic anoxic event in southiberian palaeomargin the early toarcian oceanic anoxic event t oae represents one of the major alterations of the carbon cycle of the mesozoic period despite being globally recognized and particularly represented within the tethys realm its expression in the sedimentary record is highly variable depending on the studied section which suggests local environmental factors exert a major control on the resulting lithological appearance of the event we investigated the fuente vidriera section in the eastern external subbetic of the betic cordillera spain where the lower jurassic is represented by alternate layers of marls and many limestones and the t oae is identified by a major delta c 13 excursion micropalaeontological ichnofacies and geochemical evidences 1 for this study we analyzed pyrite framboid size distribution of the sedimentary sequence in fuente vidriera the outcome according to previous studies on pyrite framboid distribution is contradictory when compared to all other evidences suggesting oxygen depletion during the t oae the results have been reinterpreted in the light of crystal size distribution theory and we conclude that not only growth time but also geochemical environment controls pyrite formation since growth time is directly related to burial rates this approach allows us to reconstruct relative variations of sedimentation rates during the early jurassic in this location based on the obtained results we provide new evidences for wide spread transgression during the early toarcian in the south iberian palaeomargin which induced low sedimentation rate and lower energetic conditions as well as favored oxygen impoverished bottom waters c 2015 elsevier b v all rights reserved less

geochemical characterization of source rocks and crude oils in the upper cretaceous qingshankou formation changling sag southern songliao basin abstract the upper cretaceous qingshankou formation is one of the main exploration target in the changling sag southern songliao basin however the origin of source rock deposition and crude oils remains undiscovered a comprehensive geochemical study including rock eval pyrolysis gas chromatography mass spectrometry and carbon isotope analysis on fifteen crude oils and twenty two source rock samples from the qingshankou formation were performed in order to provide new insights into source organic matter depositional environment and correlation between crude oils and source rocks bulk geochemical analysis on source rock samples indicates that the lower member of the qingshankou formation has more hydrocarbon generating potential than the middle member these two potential source rock members were interpreted to be deposited in slightly different environments and have different sources of organic matter determined by biomarker assemblages the lower member is organically rich average toc 1 27 wt oil prone mature and deposited under anoxic conditions with more contribution from sapropelic organic matter the middle member is organically poor average toc 0 78 wt gas prone less mature and deposited under less anoxic conditions with more terrigenous organic matter input biomarker fingerprints and carbon isotope compositions suggest that all the crude oils were genetically related and could be classified into one oil family which has significant contribution from the lower member source rocks and minor contribution from the middle member source rocks

interseismic strain accumulation and anthropogenic motion in metropolitan los angeles 1 we use global positioning system gps geodesy and synthetic aperture radar sar interferometry to distinguish between interseismic strain accumulation and anthropogenic motion in metropolitan los angeles we establish a relationship between horizontal and vertical seasonal oscillations of the santa ana aquifer use this relationship to infer cumulative horizontal anthropogenic motions from cumulative vertical motions caused by water and oil resource management and estimate horizontal interseismic velocities corrected for anthropogenic effects vertical anthropogenic rates from 1992 to 1999 are slower than 3 mm yr 1 in the santa ana and san gabriel aquifers and faster than 5 mm yr 1 in the chino aquifer and in many oil fields inferred horizontal anthropogenic velocities are faster than 1 mm yr 1 at 18 of 46 gps sites northern metropolitan los angeles is contracting with the 25 km south of the san gabriel mountains shortening at 4 5 1 mm yr 1 95 confidence limits the thrust fault in an elastic edge dislocation model of the observed strain is creeping at 9 2 mm yr 1 beneath and north of a position 6 2 km deep and 8 8 km north of downtown los angeles the model fault is near the los angeles segment of the puente hills thrust but south of the sante fe springs segment of the thrust disagreement between the 6 km locking depth in the model and the 15 km seismogenic depth inferred from earthquakes suggests that the elastic continuum model may be unsatisfactory models with different stiffnesses of sedimentary basin and crystalline basement must be investigated

pyrite morphology in the first member of the late cretaceous qingshankou formation songliao basin northeast china abstract the study of sedimentary pyrite morphological characteristics provides useful information on depositional environments and early diagenic processes and can be used as an indicator of redox conditions in ancient lake bottom waters the results of this study in the songliao basin in northeastern china show that euhedral crystals and framboids are the dominant pyrite forms in the mudstones of the first member of the qingshankou formation k2qn1 the framboidal size distribution indicates that during the deposition of k2qn1 redox conditions in the bottom water fluctuated from oxic dysoxic to euxinic anoxic to oxic dysoxic the presence of euxinic anoxic bottom water suggests that an anoxic event developed in the songliao ancient lake and continued for 196 ka the development of an anoxic bottom environment was the most important factor in hydrocarbon source rock formation in the songliao basin

formation and evolution of nonmarine petroleum in songliao basin china in large lake basins source rocks containing sapropelic kerogen have a high transformation ratio and a high potential for petroleum and they offer the material basis for the formation of a large nonmarine oil field on the basis of geologic and geochemical data and the results of thermal simulation of kerogen it is confirmed that the maturation sequence of kerogen is type i type ii and type iii

permanent scatterer insar reveals seasonal and long term aquifer system response to groundwater pumping and artificial recharge received 4 may 2007 revised 30 july 2007 accepted 10 october 2007 published 5 february 2008 1 permanent scatterer insar psinsark p rovides an ew high resolution methodology for detecting and precisely measuring long term and seasonal aquifer system response to pumping and recharge in contrast to conventional insar the permanent scatterer methodology utilizes coherent radar phase data from thousands of individual radar reflectors on the ground to develop displacement time series and to produce velocity field maps that depict aquifer system response with a high degree of spatial detail in this study we present the first results of a prototype study in las vegas valley nevada that demonstrate how this methodology can be utilized in heavily pumped groundwater basins to analyze aquifer system response to long term and seasonal pumping we have developed a series of velocity field maps of the valley for the 1992 1996 1996 2000 and 2003 2005 time periods that show that despite rising water levels associated with an artificial recharge program long term residual inelastic aquifer system compaction subsidence is continuing in several parts of the valley in other areas however long term subsidence has been arrested and locally reversed the seasonal elastic responses to alternating pumping and recharge cycles were segregated from the long term trends and analyzed for spatial and temporal patterns the results show oscillations in which the maximum seasonal responses are associated with the late stages of the annual artificial recharge cycles and that similar seasonal subsidence signals are related to summer pumping cycles the differentiation of the seasonal response through the use of time series data further allows the estimation of elastic and inelastic skeletal storage coefficients providing a basis for future work that could characterize the storage properties of an aquifer system with a high degree of spatial resolution

geochemical compositional mapping of lower jurassic trace fossils palaeoenvironmental significance and methodological implications abstract analyses of x ray microfluorescence xrf elemental maps of the ichnofossil assemblages from the upper pliensbachian lower toarcian marl limestone rhythmite of the south iberian palaeomargin betic cordillera se spain show that the compositions of burrow infills are geochemically and mineralogically different with respect to the surrounding sediment xrf elemental maps and back scattered electron images show pyrite framboids within the burrows and enrichment in fe and s relative to the host sediment this is congruent with the position of burrows beneath the redox boundary at the time of their active or passive sedimentary infilling organic matter that accumulated at the seafloor was not preserved due to oxidation and consumption by benthic organisms however burrows located beneath the redox boundary served as traps for organic matter preservation the composition of burrow fills reflects the original signal of the redox conditions of pore waters below the sediment water interface which was not preserved in the surrounding sediment the xrf elemental maps also show that some trace fossils from limestone and marly limestone intervals contain high concentrations of si al k zn cr and ti with respect to the surrounding sediment this may reflect enrichment of clay minerals in the burrow fills derived from overlying marly layers this work proposes the use of elemental imaging of trace fossils prior bulk rock geochemical analyses in order to evaluate the potential for biogenic heterogeneity and elemental partitioning before sampling geochemical analysis of trace fossils represents an additional tool that may be of use in hydrocarbon exploration

stress triggering in thrust and subduction earthquakes and stress interaction between the southern san andreas and nearby thrust and strike slip faults 1 we argue that key features of thrust earthquake triggering inhibition and clustering can be explained by coulomb stress changes which we illustrate by a suite of representative models and by detailed examples whereas slip on surface cutting thrust faults drops the stress in most of the adjacent crust slip on blind thrust faults increases the stress on some nearby zones particularly above the source fault blind thrusts can thus trigger slip on secondary faults at shallow depth and typically produce broadly distributed aftershocks short thrust ruptures are particularly efficient at triggering earthquakes of similar size on adjacent thrust faults we calculate that during a progressive thrust sequence in central california the 1983 mw 6 7 coalinga earthquake brought the subsequent 1983 mw 6 0 nunez and 1985 mw 6 0 kettleman hills ruptures 10 bars and 1 bar closer to coulomb failure the idealized stress change calculations also reconcile the distribution of seismicity accompanying large subduction events in agreement with findings of prior investigations subduction zone ruptures are calculated to promote normal faulting events in the outer rise and to promote thrust faulting events on the periphery of the seismic rupture and its downdip extension these features are evident in aftershocks of the 1957 mw 9 1 aleutian and other large subduction earthquakes we further examine stress changes on the rupture surface imparted by the 1960 mw 9 5 and 1995 mw 8 1 chile earthquakes for which detailed slip models are available calculated coulomb stress increases of 2 20 bars correspond closely to sites of aftershocks and postseismic slip whereas aftershocks are absent where the stress drops by more than 10 bars we also argue that slip on major strike slip systems modulates the stress acting on nearby thrust and strike slip faults we calculate that the 1857 mw 7 9 fort tejon earthquake on the san andreas fault and subsequent interseismic slip brought the coalinga fault 1 bar closer to failure but inhibited failure elsewhere on the coast ranges thrust faults the 1857 earthquake also promoted failure on the white wolf reverse fault by 8 bars which ruptured in the 1952 mw 7 3 kern county shock but inhibited slip on the left lateral garlock fault which has not ruptured since 1857 we thus contend that stress transfer exerts a control on the seismicity of thrust faults across a broad spectrum of spatial and temporal scales

synthetic aperture radar interferometry to measure earth s surface topography and its deformation synthetic aperture radar interferometry insar from earth orbiting spacecraft provides a new tool to map global topography and deformation of the earth s surface radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter scale accuracy these data sets aid in the analysis and interpretation of tectonic and volcanic landscapes if the earth s surface deformed between two radar image acquisitions a map of the surface dis placement with tens of meters resolution and subcentimeter accuracy can be con structed this review gives a basic overview of insar for earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of insar for mapping the topography and deformation of the earth

anatomy of the high frequency ambient seismic wave field at the tcdp borehole 1 the taiwan chelungpu fault drilling project tcdp installed a vertical seismic array between 950 and 1270 m depth in an active thrust fault environment in this paper we analyze continuous noise records of the tcdp array between 1 and 16 hz we apply multiple array processing and noise correlation techniques to study the noise source process properties of the propagation medium and the ambient seismic wave field diurnal amplitude and slowness patterns suggest that noise is generated by cultural activity the vicinity of the recording site to the excitation region indicated by a narrow azimuthal distribution of propagation directions leads to a predominant ballistic propagation regime this is evident from the compatibility of the data with an incident plane wave model polarized direct arrivals of noise correlation functions and the asymmetric arrival shape evidence for contributions from scattering comes from equilibrated earthquake coda energy ratios the frequency dependent randomization of propagation directions and the existence of correlation coda waves we conclude that the ballistic and scattered propagation regime coexist where the first regime dominates the records but the second is weaker yet not negligible consequently the wave field is not equipartitioned correlation signal to noise ratios indicate a frequency dependent noise intensity iterations of the correlation procedure enhance the signature of the scattered regime discrepancies between phase velocities estimated from correlation functions and in situ measurements are associated with the array geometry and its relative orientation to the predominant energy flux the stability of correlation functions suggests their applicability in future monitoring efforts

sensing the ups and downs of las vegas insar reveals structural control of land subsidence and aquifer system deformation land subsidence in las vegas nevada united states between april 1992 and december 1997 was measured using spaceborne interferometric synthetic aperture radar the detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures faults and sediment composition clay thickness the maximum detected subsidence during the 5 75 yr period is 19 cm comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground water levels brought about by a net reduction in ground water extraction temporal analysis also detects seasonal subsidence and uplift patterns which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability

structural model of the san bernardino basin california from analysis of gravity aeromagnetic and seismicity data 1 the san bernardino basin is an area of quaternary extension between the san jacinto and san andreas fault zones in southern california new gravity data are combined with aeromagnetic data to produce two and three dimensional models of the basin floor these models are used to identify specific faults that have normal displacements in addition aeromagnetic maps of the basin constrain strike slip offset on many faults relocated seismicity focal mechanisms and a seismic reflection profile for the basin area support interpretations of the gravity and magnetic anomalies the shape of the basin revealed by our interpretations is different from past interpretations broadening its areal extent while confining the deepest parts to an area along the modern san jacinto fault west of the city of san bernardino through these geophysical observations and related geologic information we propose a model for the development of the basin the san jacinto fault related strike slip displacements started on fault strands in the basin having a stepping geometry thus forming a pull apart graben and finally cut through the graben in a simpler bending geometry in this model the san bernardino strand of the san andreas fault has little influence on the formation of the basin the deep central part of the basin resembles classic pull apart structures and our model describes a high level of detail for this structure that can be compared to other pull apart structures as well as analog and numerical models in order to better understand timing and kinematics of pull apart basin formation

space geodetic measurement of crustal deformation in central and southern california 1984 1992 we estimate the velocity field in central and southern california using global positioning system gps observations from 1986 to 1992 and very long baseline interferometry vlbi observations from 1984 to 1991 our core network includes 12 gps sites spaced approximately 50 km apart mostly in the western transverse ranges and the coastal borderlands the precision and accuracy of the relative horizontal velocities estimated for these core stations are adequately described by a 95 confidence ellipse with a semiminor axis of approximately 2 mm yr oriented roughly north south and a semimajor axis of approximately 3 mm yr oriented east west

analog models of restraining stepovers in strike slip fault systems scaled sandbox models have successfully simulated the geometries and progressive evolution of antiformal pop up structures developed in a weak sedimentary cover above restraining stepovers in offset sinistral strike slip fault systems in rigid basement models were run both with and without synkinematic sedimentation which was added incrementally to cover the growing antiformal structures vertical and horizontal sections of the completed models permit the full three dimensional 3 d structure of the pop ups to be analyzed in detail three representative end member experiments are described 30 underlapping restraining stepovers 90 neutral restraining stepovers and 150 overlapping restraining stepovers the experimental pop ups are typically sigmoidal to lozenge shaped antiformal structures having geometries that are dependent on both the stepover angle and stepover width in the underlying basement faults underlapping restraining stepovers typically form elongate lozenge shaped pop ups 90 neutral restraining stepovers produce shorter squat rhomboidal pop ups and overlapping restraining stepovers produce sigmoidal antiformal pop ups trans pop up cross fault systems are characteristic at large displacements on the basement fault system above the offset principal displacement zones the pop ups are commonly small narrow positive flower structures whereas in the stepover region they widen out and become markedly asymmetric this pop up asymmetry switches across the center of the stepover where the pop ups are largely symmetical maximum rotations measured within the central highly uplifted region of the pop ups increase from 7 counterclockwise for the underlapping 30 stepovers to 14 counterclockwise for the neutral 90 stepovers to 16 counterclockwise for the overlapping 150 stepovers in models where no synkinematic sediments were added during deformation the pop up structures are bound by convex flattening upward oblique slip reverse fault systems that link downward to the offsets in the basement fault system in contrast in the begin page 234 experiments where synkinematic sediments were added incrementally during deformation the pop ups are formed by oblique slip reverse faults that steepen upward into the synkinematic strata with the formation of fault propagation growth folds the analog models are compared with natural examples of pop up structures and show strong similarities in structural geometries and stratal architectures these models may provide structural templates for seismic interpretation of complex contractional structures in offset strike slip fault systems

experimental study of the influence of oil wet calcite cements on oil migration and implications for clastic reservoirs abstract the influence of oil wet calcite cements on oil migration in clastic reservoirs is of significant interest in the field of petroleum exploration however the microscopic migration of oil in microscopic pore spaces with oil wet calcite cements has not been directly observed microscopic observations of oil migration were conducted in a glass micromodel at normal temperature and pressure to investigate the influence mechanism of oil wet calcite cements on oil migration in pore spaces the calcites were precipitated as cements prior to the oil migration a two dimensional glass micromodel with two interconnected spaces with the same pore throat structures was used in the experimental study a new method to create firmly adhering calcites was used to precipitate equal amounts of calcites in the two interconnected spaces the oil migration was recorded in real time under a microscope throughout the experiment the experimental results show that oil migration occurs faster in spaces with than without oil wet calcites during the oil migration in the pore throat spaces the oil migrates towards the surfaces of the oil wet calcites when the oil is in contact with the calcites the presence of oil wet calcites significantly reduces the oil breakthrough pressure the electrostatic attraction between the carboxylic groups and calcites and the intermolecular forces between the carboxylic groups and organic molecules in the oil cause the oil migration towards the surfaces of the oil wet calcites the experimental results indicate that oil preferentially migrates into clastic reservoirs that possess appropriate amounts of oil wet calcite cements precipitated prior to oil emplacement

the origin of pyrite mineralization implications for late cambrian geology of the holy cross mountains south central poland abstract this paper presents results of a petrographic mineralogical and geochemical study of ore gangue and rock forming minerals that occur within the upper cambrian furongian age siliciclastic rocks of the wi niowka massif western part of the main range holy cross mountains south central poland this area is characterized by the presence of ubiquitous pyrite that makes up two stratiform mineralization zones assigned to the early and middle late cambrian giving rise to acid mine drainage the oldest zone comprises additionally sedimentary breccias with intraclast supported pyrite cement the predominant microscopic colloform and partly framboidal pyrite typically shows high concentrations of as up to 8 23 wt and a distinct enrichment in the light sulfur isotope 34s from 41 4 to 23 6 the occurrences of large amounts of as rich pyrite showing strongly negative 34s values are rather uncommon in paleozoic sedimentary formations worldwide that exhibit distinctly smaller amounts of as and mostly enrichments in heavier sulfur isotope 34s up to 63 another specific feature of the wi niowka rock series is the presence of ree bearing aluminophosphate and phosphate minerals that occur primarily in clayey silty shales and bentonites based on the results obtained a sequence of hydrothermal index minerals was discriminated including pyrite whose grains are usually made of alternating arsenic rich and arsenic poor bands as well as paragenetic assemblages of dickite nacrite xenotime and the crandallite series of aluminum phosphate sulfate minerals both mineral composition and specific microtextures are indicative of multistage hydrothermal activity that took place in the wi niowka depositional basin during the late cambrian time this is in distinct contrast to the remaining part of the main range which is devoid of the hydrothermal pyrite imprint moreover the results of this study give insight into the complex sedimentary and early diagenetic history of the southwestern passive margin of the baltica craton this currently makes up a part of the ysogory block terrane that borders on the trans european suture zone separating the precambrian east european craton from the paleozoic platform of central europe this study is important because we still lack the full knowledge about the hydrothermal processes that took place in early paleozoic depositional basins

depositional environment thermal maturity and shale oil potential of the cretaceous qingshankou formation in the eastern changling sag songliao basin china an integrated organic and inorganic geochemistry approach abstract the changling sag in the petroliferous songliao basin has produced large amounts of conventional petroleum but studies on unconventional resources are rare a suite of core samples from the cy 1 well drilled in the eastern changling sag was analysed employing a series of micropetrographic geochemical and pyrolysis techniques to reveal the shale oil potential of the lower k2qn1 and middle k2qn2 qingshankou formation in this area for the first time from the lower k2qn1 upwards the sampled section the ratio of k al delineates an increasing palaeo temperature trend but still within a warm climate based on element ratios al2o3 toc and tio2 toc the highest terrestrial matter and nutrient supply on average occurred in the lower k2qn1 triggering bioproductivity toc ts and fe mn show that bottom water anoxia prevailed in the upper k2qn1 and lower k2qn2 providing excellent conditions for organic matter om preservation as compared to the lower k2qn1 high maturity of the studied layers is implied by e g vitrinite reflectance vrr of 1 03 1 09 tmax values over 445 c and molecular organic geochemical indices which correlate very well with vrr kinetic data on petroleum generation from open system pyrolysis were implemented in a numerical 1d basin and petroleum system model the k2qn1 has generated and expelled large amounts of petroleum 78 and 36 transformation of kerogen to petroleum based on kinetics of the low mature qingshankou shale om consisted originally of type i ii kerogen but has lost more than half of its original hydrocarbon generation potential upon maturation oil saturation index osi and s1 suggest that the studied layers show fair shale oil potential but are regarded as good conventional petroleum source rocks a newly proposed shale oil potential index sopi takes also thickness into account application to the qingshankou formation implies that the lower k2qn2 holds the highest shale oil potential

paleo ocean redox environments of the upper ordovician wufeng and the first member in lower silurian longmaxi formations in the jiaoshiba area sichuan basin a study of paleo ocean redox environments is important for understanding the deposition of black shale and has practical implications for shale gas exploration here we selected a total of 52 shal

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

characterization of land deformation hydraulic head and aquifer properties of the gorgan confined aquifer iran from insar observations abstract in this study interferometric synthetic aperture radar insar is applied to analyze the land deformation across the gorgan plain iran where recent droughts and over exploitation of groundwater leading to widespread subsidence having significant long term and seasonal signals in head measurements analysis of tops s1 month scaled images from october 2014 to october 2016 exhibits significant inelastic 70 mm yr on average and seasonal elastic ranging from about 20 to 132 mm vertical land deformation over the gorgan confined aquifer system gcas according to the decomposed vertical displacement map the investigations indicate that these significant deformations are due to both severe head decline up to 2 m yr and the presence of thick aquitards intervening aquifers to obtain elastic land deformation totally recoverable and static head components the inelastic partially recoverable and long term head decline trends are removed by lines fitted to the land deformation and head time series respectively having a high cross correlation coefficient between the seasonal components of head and land deformation time series ranging from 0 60 to 0 93 0 78 on average we use a joint well insar data analysis to estimate bulk aquifer parameters of the elastic skeletal storativity 0 0035 to 0 0142 0 0085 on average specific storage 1 54 10 5 to 7 68 10 5 m 1 4 35 10 5 m 1 on average and compressibility 1 50 10 10 to 7 40 10 10 n m 2 4 20 10 10 n m 2 on average at 14 piezometer locations insar derived aquifer storage properties are reasonably correlated with the hydrogeological setting of gcas moreover the elastic land deformation data are acceptably transformed to head fluctuations at 14 piezometers and several arbitrary point locations it is observed that the heads reconstructed from insar and measured in piezometers are consistent over a broad portion of gcas seasonal elastic land deformations occurred between wet and dry seasons in 2015 are also used to map the confining degree across gcas the higher confining degree has been observed in those areas of higher subsidence signatures implying that the subsidence potential in confined aquifers is higher than that of unconfined aquifers in this study we have demonstrated more benefits of the insar observations in estimating aquifer storage properties and predicting head in confined aquifers of significant subsidence signatures with better temporal and spatial resolution than that can be retrieved from hydrogeological data alone

a joint analysis of gps displacement and grace geopotential data for simultaneous estimation of geocenter motion and gravitational field this work is funded by the university of newcastle to support nasa s grace and grace follow on projects as an international science team member to the missions and by australian research council dp170100224 as well as nasa support to j sauber as a science team member

marine transgressional events in the gigantic freshwater lake songliao paleontological and geochemical evidence abstract the fossil remains of euryhaline organisms in the mesozoic cenozoic non marine sedimentary records of eastern china may have resulted from either marine transgressions or inland hypersaline lacustrine environments paleontological and organic geochemical results of this study have provided new evidence for marine transgressional events in the gigantic freshwater lake songliao during the late cretaceous

pyrite framboids in the permian triassic boundary section at meishan china evidence for dysoxic deposition pyrite framboid evidence from the permian triassic global stratotype at meishan china indicates the late permian mass extinction is closely associated with a dramatic decline of benthic oxygen levels sizes and abundances of the framboids were determined from acid residues and in situ on polished sections of the samples the framboids are abundant in the thin pyrite lamina on the top of bed 24e the upper layer of bed 24 and beds 25 26 and 29 rare in bed 24e and bed 28 but absent in bed 27 they have narrow size distributions with average diameters from 4 6 mu m to 8 7 mu m which are similar to those formed under anoxic dysoxic conditions the abundances and mean diameters of the pyrite framboids indicate redox conditions of deposition changing from upper dysoxia bed 24e and lower dysoxia pyrite lamina beds 25 and 26 to oxygenation bed 27 and again to upper dysoxia bed 28 and lower dysoxia bed 29 our discovery confirms a worldwide dysoxic marine event during the permian triassic transition suggestive of a direct relationship with the permian triassic marine mass extinction c 2007 elsevier b v all rights reserved

fault zone imaging from correlations of aftershock waveforms we image an active fault zone environment using cross correlations of 154 15 s long 1992 landers earthquake aftershock seismograms recorded along a line array a group velocity and phase velocity dispersion analysis of the reconstructed rayleigh waves and love waves yields shear wave velocity images of the top 100 m along the 800 m long array that consists of 22 three component stations estimates of the position width and seismic velocity of a low velocity zone are in good agreement with the findings of previous fault zone trapped waves studies our preferred solution indicates the zone is offset from the surface break to the east 100 200 m wide and characterized by a 30 velocity reduction imaging in the 2 6 hz range resolves further a high velocity body of similar width to the west of the fault break symmetry and shape of zero lag correlation fields or focal spots indicate a frequency and position dependent wavefield composition at frequencies greater than 4 hz surface wave propagation dominates whereas at lower frequencies the correlation field also exhibits signatures of body waves that likely interact with the high velocity zone the polarization and late arrival times of coherent wavefronts observed above the low velocity zone indicate reflections associated with velocity contrasts in the fault zone environment our study highlights the utility of the high frequency correlation wavefield obtained from records of local and regional seismicity the approach does not depend on knowledge of earthquake source parameters which suggests the method can return images quickly during aftershock campaigns to guide network updates for optimal coverage of interesting geological features

groundwater pumping and land subsidence in the emilia romagna coastland italy modeling the past occurrence and the future trend 1 the emilia romagna coastland south of the po river delta italy has experienced a dramatic land settlement mainly due to the large groundwater withdrawal related to the local economic and tourist development started in the early 1950s although the use of surface water has reduced the settlement rate over the last three decades anthropogenic land subsidence still continues in a few kilometer wide coastal strip at a rate larger than the natural one the occurrence is reconstructed since 1946 with the aid of advanced finite element flow and poromechanical models implemented with a realistically detailed geology of the regional shallow multiaquifer system the models have been calibrated against the piezometric leveling and extensometer records observed over the last 50 years and a land subsidence prediction in 2016 is performed the results show that the extensive groundwater pumping that occurred in the past is most likely the main cause of the recent land settlement as well because of the delayed compaction of the clay aquitards comprised between the depleted aquifers however the available pumping data do not allow for a thorough understanding of the current local settlement process along the coastline which is the most vulnerable area of the emilia romagna region from an environmental viewpoint if the planned scenario of groundwater resource management will be implemented anthropogenic land subsidence is bound to become a marginal problem for the central and northern portion of the emilia romagna coastland

simulating the recent evolution of the southern big bend of the san andreas fault southern california 1 the southern big bend of the san andreas fault has been interpreted to have successively abandoned two strands the mission creek and mill creek strands of the san andreas fault during the past 1 ma before taking up activity along its present day configuration this evolution is simulated within three dimensional models to explore the hypothesis that fault systems evolve to increase mechanical efficiency the three dimensional boundary element method models are validated by comparison of modeled fault slip rates and uplift rates with geologic data the model results match well the geologic strike slip rates and uplift patterns overestimation of reverse slip rates along the northern san bernardino mountains may reflect model assumptions of fault geometry the partitioning of slip among active faults changes between the three phases of southern san andreas fault evolution revealing 1 a trade off in strike slip rates between the san jacinto and san andreas faults 2 a trade off between strike slip rates on the san andreas fault and reverse slip along faults associated with uplifting the san bernardino mountains and 3 a trade off in strike slip rates along the san andreas and strike slip rates along the eastern california shear zone mechanical efficiency of the entire model increases from the mission creek to mill creek fault configuration and decreases from the mill creek configuration to the present day configuration the decrease in mechanical efficiency with the transition to the present day fault geometry may reflect gaps in our understanding of tectonic loading and or fault geometry

forecasting the evolution of seismicity in southern california animations built on earthquake stress transfer 1 we develop a forecast model to reproduce the distribution of main shocks aftershocks and surrounding seismicity observed during 1986 2003 in a 300 310 km area centered on the 1992 m 7 3 landers earthquake to parse the catalog into frames with equal numbers of aftershocks we animate seismicity in log time increments that lengthen after each main shock this reveals aftershock zone migration expansion and densification we implement a rate state algorithm that incorporates the static stress transferred by each m 6 shock and then evolves coulomb stress changes amplify the background seismicity so small stress changes produce large changes in seismicity rate in areas of high background seismicity similarly seismicity rate declines in the stress shadows are evident only in areas with previously high seismicity rates thus a key constituent of the model is the background seismicity rate which we smooth from 1981 to 1986 seismicity the mean correlation coefficient between observed and predicted m 1 4 shocks the minimum magnitude of completeness is 0 52 for 1986 2003 and 0 63 for 1992 2003 a control standard aftershock model yields 0 54 and 0 52 for the same periods four m 6 0 shocks struck during the test period three are located at sites where the expected seismicity rate falls above the 92 percentile and one is located above the 75 percentile the model thus reproduces much but certainly not all of the observed spatial and temporal seismicity from which we infer that the decaying effect of stress transferred by successive main shocks influences seismicity for decades finally we offer a m 5 earthquake forecast for 2005 2015 assigning probabilities to 324 10 10 km cells

carbonate cement stratigraphy and timing of diagenesis in a miocene mixed carbonate clastic sequence offshore sabah malaysia constraints from cathodoluminescence geochemistry and isotope studies a mixed carbonate clastic sequence is one of several miocene hydrocarbon bearing reservoirs in the northwestern sabah basin this sequence consists of bioclast rich sandstones interpreted as prograding storm shoal deposits the sequence contains a complex variety of carbonate nodules the sequence has undergone nine stages of cementation that completely occluded pores each stage represents a distinctive cement texture precipitating at specific temperatures and burial conditions the diagenetic evolution began with a syndepositional iron free marine calcite ca1 followed by an early methane derived dolomite do1 bladed calcite ca2 blocky vein filling fe calcites ca3ca4 clay mineral associated dolomite do2 fe dolomite and ankerite do3do4 and late iron rich calcite ca5 each stage of cement has distinctive sr2 mn2 mg2 fe2 ca2 and na contents reflecting changes in the palaeo porefluid systems with time the cements are correlatable over the whole study area precipitation occurred from very early to late stages of diagenesis at near surface to 2 0 km depths with progressive burial and temperature increase oxygen isotope values become strongly negative stage ca4 13c 0 5 pdb 18o 5 7 pdb the cements were precipitated at 20 75 c the source of carbon varies from marine dissolved carbonates to fermentation of organic matter methane meteoric waters and possibly hydrothermal fluids strontium isotope dating of do1 with 13c 32 5 pdb 18o 2 60 pdb and do2 13c 3 0 pdb 18o 2 5 pdb dolomites indicates that these dolomitization events took place at 10 5 ma and 8 9 ma respectively assuming precipitation within a completely open seawater system the do1 dolomite was precipitated from a methane derived brine at the boundary between the serravallian and tortonian stages after major uplift and induced faulting at a sea level lowstand the do2 dolomite was precipitated during intermediate to deep burial diagenesis during smectite illite transformation before hydrocarbon emplacement

long term slip rate of the southern san andreas fault from 10be 26al surface exposure dating of an offset alluvial fan we determine the long term slip rate of the southern san andreas fault in the southeastern indio hills using 10 be and 26 al isotopes to date an offset alluvial fan surface field mapping complemented with topographic data air photos and satellite images allows precise determination of piercing points across the fault zone that are used to measure an offset of 565 80 m a total of 26 quartz rich cobbles from three different fan surfaces were collected and dated the tight cluster of nuclide concentrations from 19 samples out of 20 from the offset fan surface implies a simple exposure history negligible prior exposure and erosion and yields an age of 35 5 2 5 ka the long term slip rate of the san andreas fault south of biskra palms is thus 15 9 3 4 mm yr this rate is about 10 mm yr slower than geological 0 14 ka and short term geodetic estimates for this part of the san andreas fault implying changes in slip rate or in faulting behavior this result puts new constraints on the slip rate of the san jacinto and on the eastern california shear zone for the last 35 kyr our study shows that more sites along the major faults of southern california need to be targeted to better constrain the slip rates over different timescales

high resolution interseismic velocity data along the san andreas fault from gps and insar 1 we compared four interseismic velocity models of the san andreas fault based on gps observations the standard deviations of the predicted secular velocity from the four models are larger north of the san francisco bay area near the creeping segment in central california and along the san jacinto fault and the east california shear zone in southern california a coherence spectrum analysis of the secular velocity fields indicates relatively high correlation among the four models at longer wavelengths 15 40 km with lower correlation at shorter wavelengths to improve the short wavelength accuracy of the interseismic velocity model we integrated interferometric synthetic aperture radar insar observations initially from advanced land observing satellite alos ascending data spanning from the middle of 2006 to the end of 2010 totaling more than 1100 interferograms with gps observations using a sum remove filter restore approach the final insar line of sight data match the point gps observations with a mean absolute deviation of 1 5 mm yr we systematically evaluated the fault creep rates along major faults of the san andreas fault and compared them with creepmeters and alignment array data compiled in uniform california earthquake rupture forecast version 2 ucerf2 moreover this insar line of sight dataset can constrain rapid velocity gradients near the faults which are critical for understanding the along strike variations in stress accumulation rate and associated earthquake hazard

mapping regional land displacements in the venice coastland by an integrated monitoring system abstract an original integrated monitoring method is designed to infer an accurate and reliable figure of regional land displacements in coastal areas where the presence of internal waters wetlands farmlands urban and industrial centers usually reduces the efficiency of single ground based and satellite based measuring techniques five different methods i e spirit leveling differential global positioning system dgps continuous gps cgps interferometric synthetic aperture radar insar and interferometric point target analysis ipta are integrated into a subsidence integrated monitoring system sims to overcome the limits characterizing each technique the sims has been used over the past decade to provide a new image of the land displacements in the venice region the result exhibits a resolution never obtained before the central lagoon including the city of venice shows a general stability while the northern and southern lagoon extremities and their related catchment sectors sink with serious rates averaging 3 to 5 mm year the sinking rates increase up to 10 15 mm year in the coastland south of the lagoon relatively small uplifts less than 1 mm year are observed at the alpine foothills and in a wide area comprised between the euganean hills and the lagoon the observed land displacements have been associated to the geological features of the study region i e tectonics seismicity differential consolidation of the middle upper pleistocene and holocene deposits and to anthropogenic activities such as land reclamation and groundwater withdrawal

framboidal chalcopyrite and bornite constrain redox conditions during formation of their host rocks in the copper stratabound mineralization of picachos north central chile abstract the picachos project is a copper deposit that occurs in manto type orebodies in north central chile and it exhibits common features of chilean stratabound or manto type copper deposits 1 an increase of copper contents from the margins to the centre of the orebodies 2 sodic and potassic hydrothermal alteration of host rocks with subsequent chloritization and sericite alteration and 3 its occurrence in sequences of limestones that are intercalated with volcanic rocks the most salient characteristic of the picachos project is the presence of pervasive framboidal pyrite in both the non mineralized limestones and the host rocks of the copper mineralization these framboidal pyrites are well preserved probably due to their close relationship with organic matter and have no evident textures of overgrowth recrystallization or dissolution moreover framboidal chalcopyrite and bornite are formed in the external and internal areas respectively of the orebodies sharing common morphological characteristics with framboidal pyrite and are formed by the replacement of the original pyrite framboids without changing their shape and size distribution representative size distributions of framboidal pyrite chalcopyrite and bornite are determined using high resolution x ray tomography micro ct this study highlights the effectiveness of these analytical techniques to obtain the representative size distribution of framboids in mineralized rocks the preservation of the original framboidal texture of pyrite makes it possible to infer anoxic to near dysoxic conditions the size distributions of framboidal chalcopyrite and bornite are hypothesized to be additional potential paleo redox indicators referring to the same formation dynamic as typical framboidal pyrites

geophysical evidence for wedging in the san gorgonio pass structural knot southern san andreas fault zone southern california geophysical data and surface geology define intertonguing thrust wedges that form the upper crust in the san gorgonio pass region this picture serves as the basis for inferring past fault movements within the san andreas system which are fundamental to understanding the tectonic evolution of the san gorgonio pass region interpretation of gravity data indicates that sedimentary rocks have been thrust at least 5 km in the central part of san gorgonio pass beneath basement rocks of the southeast san bernardino mountains subtle long wavelength magnetic anomalies indicate that a magnetic body extends in the subsurface north of san gorgonio pass and south under peninsular ranges basement and has a southern edge that is roughly parallel to but 5 6 km south of the surface trace of the banning fault this deep magnetic body is composed either of upper plate rocks of san gabriel mountains basement or rocks of san bernardino mountains basement or both we suggest that transpression across the san gorgonio pass region drove a wedge of peninsular ranges basement and its overlying sedimentary cover northward into the san bernardino mountains during the neogene offsetting the banning fault at shallow depth average rates of convergence implied by this offset are broadly consistent with estimates of convergence from other geologic and geodetic data seismicity suggests a deeper detachment surface beneath the deep magnetic body this interpretation suggests that the fault mapped at the surface evolved not only in map but also in cross sectional view given the multilayered nature of deformation it is unlikely that the san andreas fault will rupture cleanly through the complex structures in san gorgonio pass

organic matter enrichment of the late triassic yanchang formation ordos basin china under dysoxic to oxic conditions insights from pyrite framboid size distributions abstract pyrite framboids are spherical or ellipsoidal compact aggregates of submicron pyrite microcrystals the various lithologies in the chang 7 member of the upper triassic yanchang formation contain abundant pyrite framboids which provide an opportunity to understand the fluctuation in paleoredox conditions and relative sedimentation rates during deposition the measured diameters of the pyrite framboids in the chang 7 member are characterized by large mean diameters 9 7 16 6 m with a wide distribution range that plots in the area indicative of dysoxic to oxic paleoredox conditions during deposition of the chang 7 sediments based on correlation analysis the strong correlation between paleoredox sensitive trace elements ratios v cr u th and cu zn and the mean size of framboids indicate that the latter can serve as a reliable indicator of paleoredox conditions the results of the framboid size distribution can also be interpreted through crystal size distribution theory csdt according to csdt the relative sedimentation rate of the chang 7 member fluctuated during deposition in parallel with fluctuation in lacustrine levels furthermore the strongly positive correlation between total organic carbon toc and paleoredox conditions indicates that although relatively high sedimentation rate may have contributed to the dysoxic oxic conditions that were harmful to the preservation of organic matter but it may also have brought nutrients to increase productivity similarly the correlation between toc and relative sedimentation rates suggests that the relative sedimentation rates can affect organic matter enrichment in several ways a high sedimentation rate is favourable for the preservation of organic matter which can be prevented from oxidation but large amounts of sediments can dilute the organic matter which reduces the organic matter abundance in a potential source rock

the morphology of strike slip faults examples from the san andreas fault california fault zones are seldom straight nor are fractures within them continuous permanent strain fields are imprinted near a fault of complex geometry as a result of continued slip these strain fields may be manifest as vertical deformation near the fault strain fields that increase area result in subsidence and strain fields that reduce area result in uplift although these effects are modified by erosion and deposition the general features of fault zone morphology are a consequence of the geometry and slip distribution along strike graphical views of strain fields associated with simple vertical strike slip faults are derived using boundary element methods if the fault is straight and parallel to the applied shear strain the hills and valleys resulting from finite fault rupture are separated by the fault trace this is rarely observed in nature instead strike slip faults cut through hills and valleys apparently of their own making we show this to be a consequence of segments of the fault being nonparallel to each other and to the overall applied shear strain coseismic strains are large but transient since they are substantially annulled by rupture on contiguous fault segments we test our theory with examples from parts of the san andreas fault system in california the morphologies of the parkfield region and the southern san andreas fault in the coachella valley are shown to be consistent with plausible distributions of slip on mapped surface faults the location of the salton sea appears to be a consequence of a reduction of slip on the san andreas fault toward the brawley seismic zone

global positioning system constraints on fault slip rates in southern california and northern baja mexico we use global positioning system gps estimates of horizontal site velocity to constrain slip rates on faults comprising the pacific north america plate boundary in southern california and northern mexico we enlist a simple elastic block model to parameterize the distribution and sum of deformation within and across the plate boundary we estimate a pacific north america relative plate motion rate of 49 3 mm yr one standard deviation consistent with nuvel 1a estimates we are able to resolve robust slip rate estimates for the southernmost san andreas san jacinto and elsinore faults 26 2 9 2 and 6 2 mm yr respectively and for the imperial and cerro prieto faults 35 2 and 42 1 mm yr respectively accounting for about 86 of the total plate motion the remaining 14 appears to be accommodated to the west of these fault systems probably via slip along the san clemente fault and or the san miguel vallecitos rose canyon and newport inglewood fault systems these results are highly consistent with paleoseismic estimates for slip rates implying that off fault strain accumulation within the deforming zone of the plate boundary is largely elastic we estimate that the seismically quiescent southernmost san andreas fault has incurred about 8 2 m of slip deficit over the last few hundred years presumably to be recovered during a future large earthquake

drought driven transient aquifer compaction imaged using multitemporal satellite radar interferometry in unconsolidated heterogeneous aquifer systems low rates of pore pressure diffusion of applied effective stresses due to the drainage of thick low permeability clay rich layers with time constants of decades to centuries cause delayed residual permanent compaction and land subsidence current application of satellite differential radar interferometry dinsar differential interferometric synthetic aperture radar to estimate aquifer hydraulic properties compressibility and or storage in these systems is limited by the temporal availability of synthetic aperture radar data 1992 present in this paper we study the degree of aquifer compaction due to water extraction using dinsar through an example in southeast spain ground deformation data indicate large scale deformation and in particular the discovery of the highest rates of groundwater related land subsidence recorded in europe 10 cm yr affecting the guadalentin river basin 200 km 2 the largest tributary of the segura river modeling of the ground surface time series of the guadalentin basin indicates that deformation is mainly driven by nonlinear time delayed flow processes in the underlying aquifer after a drought period 1990 1995 the aquifer responded with an exponential decay of the land subsidence lasting 8 yr suggesting transient groundwater pore pressure flow we show that multitemporal satellite radar interferometry analysis and its modeling can be a stimulating way to study nonlinear soil mechanics and groundwater flows at aquifers a deeper understanding of such processes could help the management of water resources and land subsidence of unconsolidated coastal and quaternary alluvial aquifers in a highly evolving climate region the mediterranean sea and elsewhere

uplift of the western transverse ranges and ventura area of southern california a four technique geodetic study combining gps insar leveling and tide gauges

marine incursion events in the late cretaceous songliao basin constraints from sulfur geochemistry records abstract songliao basin in ne china developed the most productive oilfield in the world sourced from terrestrial rocks the main source rock of the basin includes member 1 of the qingshankou k2qn1 and members 1 and 2 of the nenjiang formation k2nj1 2 however the exact reasons for the formation of the source rock especially the k2qn1 are still controversial former paleontological and organic geochemical research suggested that organic matter was deposited during marine incursion events of k2qn1 but further geochemical evidence is needed this paper explores the distinct sulfate levels that distinguish marine from fresh waters of the songliao paleo lake we undertook a systematic investigation the sulfur geochemistry of the sediments from top of member 4 of the quantou formation k1q4 to top of member 1 of the qingshankou k2qn1 the ratio of organic carbon to the pyrite sulfur toc pys proved the previously suggested saline conditions during the deposition of k2qn1 and the pyrite sulfur isotope indicated that marine incursion may not only have occurred for k2qn1 but also for top of k1q4 the exact time for the beginning of marine incursion is to be determined the marine incursion within k2qn1 is not strong and partially controlled by the fluctuation of paleo lake level the present study will be helpful for understanding the contribution of marine incursion events to the burial of organic carbon in the songliao paleo lake although further studies are still needed

delineation of faulting and basin geometry along a seismic reflection transect in urbanized san bernardino valley california fourteen kilometers of continuous shallow seismic reflection data acquired through the urbanized san bernardino valley california have revealed numerous faults between the san jacinto and san andreas faults as well as a complex pattern of downdropped and uplifted blocks these data also indicate that the loma linda fault continues northeastward at least 4 5 km beyond its last mapped location on the southern edge of the valley and to within at least 2 km of downtown san bernardino previously undetected faults within the valley northeast of the san jacinto fault are also imaged including the inferred western extension of the banning fault and several unnamed faults the rialto colton fault is interpreted southwest of the san jacinto fault the seismic data image the top of the crystalline basement complex across 70 of the profile length and show that the basement has an overall dip of roughly 10 southwest between perris hill and the san jacinto fault gravity and aeromagnetic data corroborate the interpreted location of the san jacinto fault and better constrain the basin depth along the seismic profile to be as deep as 1 7 km these data also corroborate other fault locations and the general dip of the basement surface at least 1 2 km of apparent vertical displacement on the basement is observed across the san jacinto fault at the profile location the basin geometry delineated by these data was used to generate modeled ground motions that show peak horizontal amplifications of 2 3 5 above bedrock response in the 0 05 to 1 0 hz frequency band which is consistent with recorded earthquake data in the valley