validating earth and ocean tide models using tidal gravity measurements summary o1 and m2 observations from well calibrated spring gravimeters and superconducting gravimeters from the global geodynamics project ggp are used to test models of the earth s body tide and 10 ocean tide models it is shown that some of the ocean tide models give anomalous results in various parts of the world for example the schwiderski ocean tide model gives discrepancies in several areas and the fes series of ocean tide models have problems in the western pacific china japan and australia the majority of the high quality tidal gravity measurements in europe are in close agreement with the dehant defraigne and wahr ddw elastic and inelastic body tide models the gravimetric factors for the ddw elastic and inelastic models only differ by 0 12 per cent and the present calibration accuracy does not allow us to distinguish between these models but does reduce the previous upper bound on inelastic gravimetric factors the european observations give a phase lag of a few hundredths of a degree for the o1 body gravity tide which is consistent with the mathews inelastic body tide model at some european and worldwide stations the gravimetric factors differ by up to 0 3 per cent from the ddw model and it is suggested that further checks on the gravimeter calibrations are required accurate determinations of instrumental phase lags are now easier to achieve and the imaginary out of phase component of tidal gravity can be used for accurate tests of this component of ocean tide models

origin of high mountains in the continents the southern sierra nevada active and passive seismic experiments show that the southern sierra despite standing 1 8 to 2 8 kilometers above its surroundings is underlain by crust of similar seismic thickness about 30 to 40 kilometers thermobarometry of xenolith suites and magnetotelluric profiles indicate that the upper mantle is eclogitic to depths of 60 kilometers beneath the western and central parts of the range but little subcrustal lithosphere is present beneath the eastern high sierra and adjacent basin and range these and other data imply the crust of both the high sierra and basin and range thinned by a factor of 2 since 20 million years ago at odds with purported late cenozoic regional uplift of some 2 kilometers

biological markers in lower jurassic synrift lacustrine black shales hartford basin connecticut u s a abstract the east berlin formation lower jurassic hartford basin connecticut u s a is distinctive for its six cyclic units of lacustrine black shale and gray mudstone separated by playa and fluvial redbeds the black shales are each about a meter thick and were deposited in subtropical thermally strastified oligomictic lakes the youngest of which lakes 3 through 6 were large enough to flood most of the basin and attained depths of several tens of meters the saturate fractions of solvent extracts of organic rich black shales from each of the six lakes collected at fresh roadcuts near east berlin are dominated by extended homologous series of n alkanes alkylcyclohexanes and branched chain alkanes a striking feature of the black shales is the presence of a series of extended tricyclic terpanes from c20 to at least c41 hopanes are either not detectable or present only in subordinate quantities relative to the tricyclic terpanes the samples are depleted in hopanes in part because of the elevated maturity level mid to late oil window tricyclic terpane concentrations may also have been enhanced by fractionation effects related to oil expulsion out of the black shales in addition the original organic matter may have been exceptionally rich in tricyclic terpane precursors i e fossil lipids of prokaryotes present in anoxic moderately saline alkaline lakes

early tertiary paleogeologic map of the northern sierra nevada batholith and the northwestern basin and range the northern sierra nevada and adjacent basin and range western united states are marked by a widespread regional unconformity at the base of the eocene miocene volcanic and sedimentary section that overlies the mesozoic batholith and its wall rocks to help address controversial questions about the origin uplift and erosion of the batholith we compiled a subcrop geologic map of the unconformity prior to tertiary extension this simple but under utilized technique reveals the distribution of rock units that could have contributed detritus to the eocene miocene river channels crossing the sierra nevada and demonstrates that the mesozoic sierra nevada batholith was continuous to the northeast across the northwestern basin and range more speculatively the subcrop map implies that late cretaceous eocene erosional stripping may have been greatest above the axis of the batholith and decreased to the east thus drainage in this area may have been eastward and then switched westward in eocene miocene time

tricyclic terpane maturity parameters response to heating by an igneous intrusion the effects of thermal maturation upon the abundance and composition of the tricyclic terpanes have been investigated within a single sedimentary horizon within the dun caan shale member isle of skye scotland intruded by a 0 9 m thick tertiary dolerite dyke heating by the igneous body caused the concentrations of all 13 h 14 h and 13 h 14 h tricyclic terpanes to increase towards or within the effective oil window recording generation from abundant non hydrocarbon precursors such as kerogen and asphaltene bound components progressive changes in tricyclic terpane composition accompany these concentration changes an increase in the c23 maturity parameter towards the dyke resulted from the relatively greater rate of generation of the isomer combined with the earlier decline in concentration by degradation or isomerisation of the component the tricyclics tricyclics hopanes parameter shows a dramatic increase within the latter part of the oil window due to the greater relative thermal stability of the tricyclic terpanes the quantitative data demonstrate the importance of the processes of generation from non hydrocarbon fractions of the sedimentary organic matter and thermal degradation in the operation of tricyclic terpane maturity parameters

geochemical characteristics origins and model of lacustrine source rocks in the zhu 1 depression eastern pearl river mouth basin south china sea abstract variations in environmental and biological origins contributing to the heterogeneity of lacustrine source rocks can be illustrated in their diverse genetic facies the zhu 1 depression eastern pearl river mouth basin south china sea is characterized by two thick paleogene organic rich synrift units the wenchang and enping formations the integration of bulk geochemical and biomarker data with tectonic and sedimentary information provides the basis for a comprehensive assessment of the environmental and ecological changes through geologic time and their impact on the heterogeneity of these lacustrine source rocks both the wenchang and enping formations display wide variations in total organic carbon content and hydrogen index values as well as biomarker composition suggesting lateral and chronological changes in organic facies using gas chromatography mass spectrometry and hierarchical cluster analysis five genetic facies were identified within these two source horizons these facies represent different organic matter inputs and sedimentary and early diagenetic environments based on their distinctly different assemblages of 11 source dependent biomarker ratios four facies were distinguished in the wenchang formation and two facies were distinguished in the enping formation with one being common to both formations during the middle eocene the wenchang formation was deposited in a series of small deep lakes of laterally variable salinity acidity and biofacies during the deposition of the enping formation in the late eocene and early oligocene the previous lakes merged into fewer lakes with shallower depth and larger areal coverage with the biota becoming more uniform across the whole depression the coevolution of these lacustrine settings and their biota is closely associated with the development of the zhu 1 depression within which multiple separate sags produced by rapid mid eocene subsidence finally merged into a single depositional unit during slow subsidence in the late eocene and early oligocene accordingly an integrated model was established to provide an overview of the contrasting origins of lacustrine source rocks during the two paleogene epochs this model may have important implications for source rock prediction in the undrilled parts of the basins or for reference to source rock heterogeneity in other rift basins

organic geochemistry of a lower jurassic synrift lacustrine sequence hartford basin connecticut u s a abstract synrift terrestrial strata of the lower jurassic east berlin formation hanford basin connecticut u s a record cyclical expansion and contraction of major lakes six of which were deep enough to develop anoxic bottom waters we have studied one representative lacustrine sequence in detail sampling a new roadcut near the village of east berlin the section examined is 4 m thick with a gray silstone at the base deposited in shallow water overlain by an organic rich black shale deep water succeeded in turn by another gray siltstone deposited as the lake waters gradually receded the upper gray siltstone is chemically distinct from the lower siltstone as it contains small amounts of corrensite analcime and gypsum reflecting the increasing salinity and alkalinity of the contracting lake the samples in the center of the black shale unit contain laminae of thermally altered yellowish orange fluorescing mottled telalginite the fluorescence properties indicate a peak oil generation maturity level confirmed by a vitrinite reflectance of 1 13 and a methylphenanthrene index of 1 08 the other samples have less organic matter becoming increasingly lean towards the top and bottom of the sequence samples in the middle of the black shale unit are distinguished by the presence of an homologous series of tricyclic terpanes extending from c20 to at least c41 and by the near absence of hopanes and steranes moving upsection into the gray siltstone the samples contain markedly lessextractable organic material eom and the concentration of tricyclic terpanes relative to hopanes steadily decreases in the uppermost sample hopanes are the predominant terpanes moving downsection from the black shale into the lower gray siltstone eom and the ratio of tricyclic terpanes also decrease except in the lowermost samples which contain terpane distributions like those of the middle part of the black shale this likely is migrated material because bitumen fills microfractures and extensive megafractures the lack of hopanes and steranes in the black shales cannot simply be a maturation effect as these biomarkers appear in the adjacent beds instead the manual terpane distributions may indicate a changing depositional environment documenting the geochemical evolution of the lake or more likely they may result from fractionation during expulsion of petroleum from these mature source rocks

distribution and evolution of tricyclic terpanes in lacustrine carbonates abstract abundant and peculiar pairs of c20 to c25 tricyclic terpanes were discovered in the tertiary lacustrine carbonates of the biyang depression though all organic matter contained in the entire carbonate section are of type i kerogen the distribution of the tricyclic terpanes varies regularly with the burial depth of samples the relative concentration of 13 h 14 h isomers in the paired tricyclic terpanes declines sharply with increasing burial depth on the basis of this variation new tricyclic terpane maturity parameters for immature and early mature carbonate source rocks are proposed

comment on geodynamics of synconvergent extension and tectonic mode switching constraints from the sevier laramide orogen by michael l wells et al

facies sequences of a semi arid closed basin the lower jurassic east berlin formation of the hartford basin new england u s a the lower jurassic east berlin formation exposed in the centre of the hartford basin can be divided into six facies 1 laminated black mudstone is composed of very finely laminated organic bearing clay stone with common millimetre scale lenses of dolomitic siltstone 2 planar laminated mudstone is commonly mudcracked and composed of thickly laminated red green or grey mudstone with common centimetre scale lenses of sandstones 3 disrupted mudstone has a complex desiccation cracked fabric 4 planar and large scale trough cross stratified sandstones are composed of moderately well sorted medium to coarse grained arkoses 5 small scale cross stratified silty sandstones with common climbing ripple structure and 6 interbedded sandstones and mudstones which commonly carry desiccation cracks mudstone facies are organized into repetitive metre scale facies sequences which change gradationally upwards from laminated black mudstones to planar laminated mudstones to disrupted mudstones facies sequences have sharp tops and bottoms and record increasing desiccation upwards there are 15 such cycles in the upper 100 m of the formation in central connecticut they record long periods of dry playa mudflat aggradation punctuated by the rapid expansion and contraction of perennial lakes the sandy facies occur as single decimetre scale sedimentation units or as two or more stacked sedimentation units up to 1 m thick these record sheet floods across ephemeral floodplains

crustal structure of the northwestern basin and range province and its transition to unextended volcanic plateaus 1 the northwestern margin of the basin and range province is characterized by a transition from low magnitude 20 extension in northwestern nevada to relatively unextended volcanic plateaus in northeastern california seismic velocity and potential field modeling provides new control on the mesozoic to present tectonic evolution of this poorly understood portion of the u s cordillera we document 20 crustal thinning associated with basin and range extension from a crustal thickness of 37 km under northeastern california to 31 km under northwestern nevada that is consistent with the amount of extension recorded in the upper crust in northwestern nevada suggesting the crustal response to extension was relatively homogeneous over the entire crustal column our modeling also shows a well defined 80 km wide zone of unusually low upper crustal velocities 5 9 6 1 km s that coincide with the surface location of sparse cretaceous granites locating the elusive northern extension of the sierra nevada batholith through northwestern nevada for the first time in the subsurface combining geological and geophysical data we reconstruct the late cretaceous to present crustal evolution of this region documenting an interplay between magmatic addition to the crust erosional exhumation sedimentation and extension that has reversed the direction of crustal thinning from a west facing continental margin to an east facing interior basin margin over this time interval finally we find no evidence in northwestern nevada for unusually thick crust 40 km prior to basin and range extension

hydrogen isotopes in eocene river gravels and paleoelevation of the sierra nevada we determine paleoelevation of the sierra nevada california by tracking the effect of topography on precipitation as recorded in hydrogen isotopes of kaolinite exposed in gold bearing river deposits from the eocene yuba river the data compared with the modern isotopic composition of precipitation show that about 40 to 50 million years ago the sierra nevada stood tall 2200 meters a result in conflict with proposed young surface uplift by tectonic and climatic forcing but consistent with the sierra nevada representing the edge of a pre eocene continental plateau

tidal parameters for an inelastic earth abstract the gravimetric factors for an elliptical uniformly rotating earth are computed according to a new definition with respect to wahr s results and considering the mantle inelasticity the love numbers h and k are defined in the elliptical earth case to correspond to the love spherical definition they become latitude dependent the tidal parameters discussed in this paper are computed for an inelastic earth s mantle the numerical results show an increase of 0 4 of the gravimetric factors with respect to the wahr s values the love numbers h and k increase by 1 4 to 3 with respect to the elastic case

a comparison of tidal ocean loading models using superconducting gravimeter data 1 errors in global ocean models have been shown to be larger than the accuracy of surface gravity measurements baker and bos 2001 and also new space gravity missions ray et al 2001 in this paper we compare the tidal loading estimated using 10 different ocean tide models to the surface gravity variations observed with 12 superconducting gravimeters sg belonging to the global geodynamics project crossley et al 1999 worldwide network ocean tidal gravity variations are shown to be mostly dependent on tidal sea height variations within a radius of 5000 km precise surface gravity measurements are therefore another tool for validating ocean tidal models from short to long wavelengths in addition for example to tide gauge data in this study we also compute the tidal loading using several different available computer codes as for ocean tidal models we show that the differences between tidal loading programs are frequently larger than the error estimates of sg measurements compared to previous models both recent hydrodynamical and topex poseidon derived tidal models allow a significant reduction of discrepancies between ocean tidal observations using sg and tidal loading estimates there still remains however a nonnegligible in phase discrepancy between ocean tidal loading estimates and surface gravity observations whereas the out of phase component is much smaller we have shown that the in phase disagreement does not seem to be caused by an inaccurate determination of the sg calibration

extended tricyclic terpanes molecular markers in lower jurassic synrift lacustrine black mudstones of the hartford basin connecticut abstract the east berlin formation lowest jurassic hartford basin connecticut is distinctive for its six cyclic black and gray lacustrine mudstone units the black mudstones are each about a meter thick and were deposited in subtropical thermally stratified oligomictic lakes the youngest of which lakes 3 through 6 were large enough to flood most of the basin and attained water depths of several tens of meters from a fresh roadcut 8 km north of middletown organic rich black mudstones of lakes 3 4 and 6 were analyzed for biological markers in each case the saturate fraction predominates making up 69 75 of the total solvent extract the n alkanes in turn dominate the saturate fraction with a maximum at c sub 20 and extending to at least c sub 37 there are also extended homologous series of alkylcyclohexanes alkylbenzenes and branched chain alkanes the methylphenanthrene indices of these samples range from 0 99 to 1 12 indicating middle to late oil window maturity levels the absence of aromatic steroids except for the c sub 20 and c sub 21 triaromatics confirms the high maturity the most striking feature of these samples is the presence of a series of extended tricyclic terpanes from c sub 20 to at least c sub 46 hopanes aremore not detectable in the mudstones of lakes 4 and 6 in lake 3 hopanes are present but only in about the same concentration as the high molecular weight tricyclics the samples are depleted in hopanes in part because of the elevated maturity level there is no evidence for biodegradation less

metamorphic evolution of the luning fencemaker fold thrust belt nevada illite crystallinity metamorphic petrology and 40ar 39ar geochronology abstract the luning fencemaker fold thrust belt lftb of nevada accommodated substantial mesozoic shortening in the back arc region of the u s cordillera metamorphic grade in this belt has not been studied and timing of deformation is not well defined in this study we present new data on metamorphic grade and age of deformation in the northern lftb we focus on the d1 phase of deformation which accommodated most shortening in the belt metamorphic grade was established by petrographic study and microtextural analysis of deformed metasedimentary rocks bulk x ray diffraction and illite crystallinity analyses of slates and phyllites and microprobe analyses of metamorphic mica these techniques indicate that metamorphism during d1 deformation occurred under anchizone to epizone grade conditions at temperatures probably near 300 c timing of d1 deformation was investigated by 40ar 39ar whole rock dating of slates and phyllites age spectra indicate that d1 deformation occurred before 142 144 ma late

thermodynamic calculation of emplacement pressures for batholithic rocks california implications for the aluminum in hornblende barometer the aluminum in hornblende ah barometer has been widely used to estimate the emplacement pressure p of granitic rocks application of the barometer has remained controversial because the controls on the aluminum content of hornblende imposed by temperature t magma composition and fluid composition remain incompletely understood in this paper the p t conditions of equilibration for 19 rocks from the mesozoic batholiths of california are estimated by simultaneous evaluation of 1 the p sensitive reaction tremolite phlogopite 2 anorthite 2 albite 2 pargasite 6 quartz k feldspar and 2 previously published amphibole plagioclase thermometer equilibria p estimates for the batholiths range from 1 2 to 7 4 kbar and are consistent with independent geologic evidence the highest p samples 5 1 7 4 kbar are located near the san andreas fault furthermore it appears that regional p gradients determined by previous ah barometry studies are valid but that the absolute values of the p estimates will need to be revised somewhat 1 5 kbar i suggest that the method of this study provides a viable thermodynamics based alternative to conventional ah barometry that requires no a priori assumptions about t or bulk composition

the effect of mantle inelasticity on tidal gravity a comparison between the spherical and the elliptical earth model summary the effects of mantle inelasticity on the earth gravity response to the luni solar attraction has been computed for the two most commonly used earth models a spherical non rotating earth and an elliptical uniformly rotating earth the corresponding results are compared in this paper we conclude that the effects of mantle inelasticity on the amplitude of the gravimetric factor are less than 0 1 per cent for the non zonal tides and that the effect on the tidal gravity phase is of the order of 0 005 for frequencies between the semi diurnal and the monthly tides these results are obtained by directly integrating the equations of motion within the earth interior in the spherical case they are independently verified by introducing a new method that makes use of the causality principle whereas the effect of mantle inelasticity on tidal gravity appears to be too small to be measured its effect on the chandler wobble period is significant and results in a lengthening of about 10 days

lacustrine shales and oil shales from stellarton basin nova scotia canada organofacies variations and use of polyaromatic hydrocarbons as maturity indicators abstract the post acadian stellarton basin is a small pull apart basin in northern nova scotia the coal brook member which is the main focus of this study contains the thickest and most extensive development of oil shales within the late carboniferous stellarton formation bulk and molecular geochemistry indicate that the organic rich oil shales and black shales contain type i ii kerogen with a mixed assemblage of aquatic and terrestrial organic matter that is dominated by the former biomarker evidence indicates that these sediments were deposited under deep anoxic and fresh to brackish water lake conditions organofacies distinctions were made on the basis of several parameters that are independent of maturity and therefore suggest organic matter changes the organofacies identified are the result of water level fluctuations that are climate controlled all of the aromatic compounds evaluated as maturity parameters were seen to experience alterations in proportion to temperature in the form of either depth or geologic age that can be correlated with maturity these alterations are believed to result from changes in molecular composition maturity parameters based on the alkylbenzothiophenic and alkylnaphthalenic compounds are shown to be effective maturity parameters in lacustrine sequences particularly over the higher maturity ranges where standard maturity parameters based on steranes and hopanes are not effective

tides for a convective earth in this paper we give values of the tidal gravimetric factor as well as of the love numbers for the tidal surface displacement and for the tidal mass redistribution potential that are consistent with the presently adopted definitions we present analytical expressions for these quantities and compute numerical values for two rotating nonspherical earth models in the first model the earth is everywhere in hydrostatic equilibrium and the inner core and mantle are both elastic in the second model the earth is ellipsoidal with an inelastic mantle and with a nonhydrostatic initial state for which the effects of mantle convection and its associated boundary deformations are considered this latter model is constrained to reproduce the observed free core nutation period and global earth dynamical flattening

review of the earth tidal models and contribution of earth tides in geodynamics the attraction of the moon and the sun on the earth induces deformations of the earth body at the surface of the earth these effects are described using tidal parameters which are observed by tidal instruments and estimated using an earth model these tidal parameters are indeed computed from a linear combination of the displacement field the stress field and the potential due to the mass readjustment associated with the tides the theoretical tidal parameter values depend crucially on the model used for the interior of the earth the system of equations used in the computation contains a stress strain relationship this equation is the only one which changes when considering mantle inelasticity instead of elasticity for an inelastic mantle the stress strain relationship is a hooke law with complex and frequency dependent rheological parameters the numerical values of these rheological parameters depend on the hypotheses formulated on the earth body even after the introduction of mantle inelasticity in the equations there are still some differences between the theory and the observations by increasing the complexity of the model scientists want to decrease the difference between the theory and the observations this comparison brings answers to very important points in geophysics in particular the resonances at the free core nutation frequency and at the free inner core nutation frequency in the tidal response give the values of these earth normal mode periods and the comparison between the observed and the computed period constrains the core flattening and the jump in the density at the inner core outer core boundary respectively

apatite u th he thermochronometry as an innovative geothermal exploration tool a case study from the southern wassuk range nevada abstract extensional type geothermal systems are complicated by the interrelation between footwall advection during exhumation and the subsequent redistribution of heat by migrating hydrothermal fluids in the hanging wall the southern wassuk range wr hanging wall hosts a moderate temperature extensional type geothermal system and is ideal for studying this duality by analyzing a suite of apatite ahe and zircon zhe helium samples from the footwall and hanging wall of the southern wr young 3 4 ma ahe ages along the wr front are concentrated along the se corners of segmented footwall blocks marking the location of focused mio pliocene transtension fracture dilation and advection hydrothermally reset ahe ages along the footwall range front suggest that the hawthorne geothermal system 85 135 c is long lived and has resided at a prominent structural boundary in the wr footwall marked by localized advection and range front deformation in contrast the presence of both hydrothermally reset and non reset ahe ages from a 1 4 km deep borehole in the hanging wall basin probably indicate that the geothermal plumbing system and current manifestation as a thermal anomaly 113 c are juvenile and are controlled by the generation of newly formed faults in the hanging wall ahe ages have been shown here to greatly enhance the focusing of regional scale geothermal exploration efforts and for the first time have been used to identify and estimate the temperature of unseen hydrothermal fluids

geochemical characterization of the upper mississippian goddard formation noble ranch group and related oils in the anadarko basin of oklahoma the woodford shale is anecdotally assumed to be the major source of oil for plays in the anadarko basin including the stacked oil and condensate play in the southcentral oklahoma oil province scoop however there is little published geochemical work to confirm this assumption this study set out to identify a characteristic geochemical fingerprint for the goddard formation another potential source rock in the scoop to determine if the goddard is contributing to oil accumulations within the scoop the upper mississippian goddard formation has been a target for unconventional production in scoop since 2012 published geochemical interpretations for the goddard formation are still limited and this study represents the first detailed oil source rock correlation for the goddard in the scoop area the most characteristic geochemical signature of the goddard extracts is a predominance of tricyclic terpanes relative to the hopanes in the mass to charge ratio 191 chromatogram possibly related to enrichment via thermal stress or a unique source signature additional distinctive signatures were also identified for the triaromatic steroid hydrocarbons sesquiterpenoids and steranes the biomarker fingerprints of scoop oils are nearly identical with those of the goddard extracts in this study oils in the scoop therefore appear to originate from a mississippian source such as the goddard rather than the woodford this observation demonstrates the value of oil source rock correlation studies and suggests that there may be effective source rocks in the anadarko basin that have been overlooked in the past and should be re evaluated in detail

the relative contribution of accretion shear and extension to cenozoic tectonic rotation in the pacific northwest large cenozoic clockwise rotations defined by paleomagnetic data are an established fact in the pacific northwest and many tectonic models have been proposed to explain them including 1 rotation of accreted oceanic microplates during docking 2 dextral shear between north america and northward moving oceanic plates to the west and 3 microplate rotation in front of an expanding basin and range province stratigraphic onlap relations and local structure indicate that microplate rotation during docking was not a major contributor to the observed rotations coast range structures basin and range extension and paleomagnetic data from middle miocene 15 ma coast range rocks indicate that dextral shear is responsible for at least 40 of the post 15 ma rotation of the coast range and that basin and range extension is responsible for the remainder reconstructions based on extrapolation of this ratio back to 37 and 50 ma are consistent with reconstructions based on paleomagnetic and stratigraphic relations in older rocks and suggest that dextral shear has been a significant contributor to rotation during most of tertiary time changes in the dextral shear rotation rate over the past 50 m y correlate directly with changes in the velocity of the farallon plate parallel to the coast and provide a strong argument for oblique subduction as the driving mechanism continental reconstructions incorporating shear may provide constraints on the rate of extension in the northernmost basin and range region and suggest 17 extension since 15 ma 39 since 37 ma and 72 since 50 ma near latitude 42 n

the san andreas and walker lane fault systems western north america transpression transtension cumulative slip and the structural evolution of a major transform plate boundary abstract relative right lateral pacific north american transform motion across the western us is largely taken up by the san andreas and walker lane fault systems cumulative lateral displacement on active strands of the san andreas system is 3 4 or more times greater than across faults of the walker lane the san andreas system is transpressional while the walker lane system is transtensional the relatively more complex discontinuous and broader system of faults composing the walker lane system is attributed to lower cumulative slip and an attendant extensional component of motion greater slip accompanied by a small component of contraction has yielded the simpler more continuous and generally throughgoing set of faults that comprise the san andreas system with respect to the contrasting amounts of cumulative slip the san andreas is at a more mature stage of structural development than the walker lane despite differences in gross patterns of faulting the systems also share similarities in deformation style slip along each is locally accommodated by clockwise rotation of crustal blocks that has produced structural basins and oblique components of slip are commonly partitioned into subparallel strike slip and dip slip faults

reply to comment by e l miller et al on geodynamics of synconvergent extension and tectonic mode switching constraints from the sevier laramide orogen 1 we welcome the comment from miller et al 2012 and the opportunity to address their concerns and to expand on several aspects of the proposed geodynamic model in wells et al 2012 many of the points raised in the comment concern late cretaceous crustal anatexis and extension aspects of the proposed geodynamic model that were developed in more detail in wells and hoisch 2008 we address each of their three main points below

global atmospheric loading and gravity abstract the purpose of this paper is to model atmospheric pressure effects on surface gravity pressure corrections are usually done with the help of an empirical trans fer function called barometric admittance between pressure and gravity both measured locally we show the validity of this local approach with the help of spectral coherency between air pressure and gravity residuals after subtraction from the superconducting gravimeter observations in strasbourg france of luni solar tides polar motion and instrumental drift contributions we compute the atmospheric surface loading effects using a green s function formalism and global surface pressure data provided by the european centre for medium range weather forecasts ecmwf we model a specific oceanic response to atmospheric loading which incorporates interactions between ocean atmosphere and solid earth and differs from the classical inverted or non inverted barometer hypotheses we investigate the contribution of this global pressure correction in a 3000 day 1987 1996 tidal analysis of the french superconducting gravimeter

paleovalley morphology and fluvial system evolution of eocene oligocene sediments auriferous gravels northern sierra nevada california implications for climate tectonics and topography in the northern sierra nevada california eocene oligocene fluvial sediments the auriferous gravels rest unconformably in well defined basement incised paleovalleys providing a record of paleolandscape geomorphology and drainage system evolution paleovalley surface mapping shows that local topography and bedrock lithology controlled the location of broad terraced paleovalley segments which formed in the central and eastern metamorphic bedrock belts and subsequently became areas of significant fluvial deposition high gradient high energy deposits are present near the edges of these areas suggesting that tributaries and outlets resided in steeper narrow paleovalleys multiple strath terraces are common in broad paleovalleys indicating that incision events occurred both before deposition and during paleovalley widening followed by periods of aggradation broad paleovalley deposits contain predominantly braided stream facies deposited in an energetically variable system multiple upward fining cycles bounded by erosional surfaces are composed of alternating coarse grained channel belt and fine grained floodplain packages an overall upward fining succession suggests that the locus of fluvial deposition shifted and depositional energy waned over time as the system backfilled successive broad paleovalleys paleochannel slope estimates of 0 004 0 055 were obtained based on average grain sizes of coarse channel fills anomalously thick up to 11 m laterally continuous 1 3 km floodplain units containing kaolinite rich clay and oxisol intervals record high fine grained sediment supply driven by high rates of chemical weathering in the warm eocene climate based on sedimentary characteristics combined with floral and detrital zircon data braided stream deposition within the basin occurred from the late early eocene through late eocene and aggradation primarily occurred in broad lower gradient reaches behind a major bedrock knickpoint created in the late mesozoic early cenozoic possibly due to asymmetric batholith unroofing the diachronous localized nature of paleovalley incision and braided stream aggradation within the northern sierra nevada invalidates previous estimates of the timing and amount of range uplift based on paleochannel reconstructions and gradients both internal and external drivers influenced the evolution of the fluvial system through 1 the pattern of basin filling as the locus of deposition migrated east to west 2 the warm eocene climate which increased chemical weathering and contributed a high sediment supply and 3 changes in base level due to eustasy and or laramide tectonism this record of laramide tectonics in the sierra nevada and basin and range is important for the timing of sierra nevada uplift for tectonic reconstructions of western north america and for studies of landscape evolution in tectonically active orogens

application of biological markers in the recognition of palaeohypersaline environments the hydrocarbon fractions of a marl sample from a messinian basin in the northern appenines and four oils rozel point oil utah and three seep oils from sicily were studied

organic geochemistry of permian organic rich sediments from the sudetes area sw poland abstract lacustrine and marine sediments from the permian rift basins of southwestern poland were analysed using gc ms and petrographic techniques high pr ph ratios and carotanes and gammacerane in the lacustrine sediments indicate deposition under elevated water salinities the primary organic matter is represented by bacterial and algal lipids with variable terrestrial input marine algal lipids with minor bacterial and cyanobacterial lipids are the primary source of organic matter in the marine sediments extended hopanes n alkanes with even odd predominance and low ts tm ratios are consistent with deposition in a closed evaporitic basin with substantial carbonate sedimentation

terrane boundary reactivation barriers to lateral fault propagation and reactivated fabrics rifting across the median batholith zone great south basin new zealand prominent pre existing structural heterogeneities within the lithosphere may localise or partition deformation during tectonic events the ne trending great south basin offshore new zealand formed perpendicular to a series of underlying crustal terranes including the dominantly granitic median batholith zone which along with the boundaries between individual terranes exert a strong control on rift physiography and kinematics we find that the crustal to lithospheric scale southern terrane boundary of the median batholith zone is associated with a crustal scale shear zone that was reactivated during late cretaceous extension between zealandia and australia this reactivated terrane boundary is oriented at a high angle to the faults defining the great south basin we identify a large granitic laccolith along the southern margin of the median batholith expressed as sub horizontal packages of reflectivity and acoustically transparent areas on seismic reflection data the presence of this strong granitic body inhibits the lateral south westward propagation of ne trending faults which segment into a series of splays that rotate to align along the margin as they approach further we also identify two e w and ne sw oriented basement fabrics likely corresponding to prominent foliations which are exploited by small scale faults across the basin we show that different mechanisms of structural inheritance are able to operate simultaneously and somewhat independently within rift systems at different scales of observation the presence of structural heterogeneities across all scales need to be incorporated into our understanding of the structural evolution of complex rift systems

comparison of earth tide parameters over a large latitude difference summary gravity earth tide observations at the station of thessaloniki with a lacoste romberg gravity meter equipped with electrostatic feedback were analysed in order to obtain accurate amplitude and phase difference tidal parameters the observations cover a total number of 162 5 days the frequency transfer function of our measuring system was defined using the step response procedure the tamura tidal development was used as normal tidal potential a standard deviation of the weight unit equal to 7 007 nm s 2 resulted from the adjustment procedure before the correction due to barometric pressure changes taking into account the barometric pressure changes trough a linear regression model this standard deviation dropped to 6 821 nm s 2 showing that these changes only slightly affect the observations the computed amplitude factors and phase differences for o1 and m2 were compared with corresponding parameters from stations distributed over a large latitude difference in order to study the latitude dependence of the gravimetric body tide factors the comparison showed that in south europe the tidal parameters fit with some local discrepancies to other stations in central europe after correction for ocean load

lacustrine source rock deposition in response to co evolution of environments and organisms controlled by tectonic subsidence and climate bohai bay basin china three paleogene syn rift intervals from the bohai bay basin the most petroliferous basin in china were analyzed with sedimentological and geochemical techniques to characterize the lateral source rock heterogeneities to reveal the environmental and ecological changes through geologic time and to construct depositional models for lacustrine source rocks under different tectonic and climatic conditions the third es3 and first es1 members of the eocene shahejie formation and the oligocene dongying formation ed display widely variable total organic carbon contents hydrogen indices and visual kerogen compositions suggesting changes in organic facies from deep to marginal sediments carefully selected deep lake facies samples from any interval however display fairly uniform biomarker composition these three intervals have distinctly different biomarker assemblages which indicate weakly alkaline freshwater lakes with a moderately deep thermocline during es3 deposition alkaline saline lakes with shallow chemocline during es1 deposition and acidic freshwater lakes with deep unstable thermocline during the deposition of the dongying formation such environmental changes corresponded to changes in subsidence rate and paleoclimate from rapid subsidence and wet climate during es3 deposition through slow subsidence and arid climate during es1 deposition to rapid subsidence and wet climate during ed deposition and resulted in synchronous changes in terrigenous organic matter input phytoplankton community and primary productivity the co evolution of environments and organisms controlled by tectonic subsidence and climate accounted for the deposition and distribution of high quality lacustrine source rocks with distinctly different geochemical characteristics most rift basins experienced changes in subsidence rates and possibly changes in climates during their syn rift evolutions the models constructed in this paper may have important implications for source rock prediction in other lacustrine rift basins

upper permian lacustrine organic facies evolution southern junggar basin nw china abstract the jingjingzigou lucaogou and hongyanchi formations of the southern junggar basin together comprise over 1000 m of organic rich lacustrine facies they record an overall evolution from relatively shallow evaporative lakes to freshwater lakes associated with fluvial systems the jingjingzigou formation is characterized by low toc and hi and biomarker features such as abundant carotane consistent with a specialized saline or hypersaline biota biomarker distributions in jingjingzigou formation extracts most closely resemble oils from the giant karamay oilfield the lucaogou formation represents one of the richest and thickest lacustrine source rock intervals in the world yet it contradicts conventional lacustrine source rock models in at least two important aspects first deposition occurred at middle paleolatitudes 39 43 n rather than in the tropics second limited nutrient supply in a drainage basin dominated by intermediate volcanic rocks appears to have caused low to moderate primary productivities stable salinity stratification and low inorganic sedimentation rates in a deep lake nonetheless resulted in deposits with up to 20 toc and hi near 800 the overlying hongyanchi formation has 1 5 toc but low hi and was deposited in freshwater oxic to sub oxic lakes

a novel approach for recognition and quantification of hydrocarbon migration effects in shale sandstone sequences a detailed organic geochemical study of over 150 samples from two cores with a total combined length of 320 m 1 050 ft through sequences of interbedded source rock type shales 0 84 rm maturity and reservoir sandstones allowed recognition and quantitation of a number of migration effects detailed gas chromatography mass spectrometry of steranes and triterpanes was used to insure that samples being compared to investigate migration effects contain organic matter of a similar type thin shales interbedded in sands and the edges of thick shale units are depleted in petroleum range hydrocarbons to a much higher degree than the centers of thick shale units for the alkanes expulsion occurs with pronounced compositional fractionation effects shorter chain length n alkanes are expelled preferentially and isoprenoid alkanes are expelled to a lesser degree than their straight chain isomers based on material balance calculations expulsion efficiencies were determined and found to be very high in certain instances for thin interbedded shales they decrease from about 80 around c15 to near zero in the c25 region there is no evidence for significant redistribution of steranes and triterpanes in the two sequences compared to c15 to c25 n alkanes they appear relatively immobile the composition of the hydrocarbons impregnating parts of the reservoir sandstones is in agreement with expulsion occurring with pronounced fractionation based on molecular chain length hence consideration of bulk expulsion efficiencies gives an unrealistic picture furthermore the impregnation of a siltstone cap rock from an underlying hydrocarbon accumulation seems to have occurred by bulk oil migration and without significant fractionation the degree of hydrocarbon depletion of some of the shales of both sequences appears to be controlled by compaction and the primary migration process appears to have occurred with chromatographic separation the migration phenomena observed in both sequences lead us to propose that the main phase of expulsion can be preceded by an earlier sta e during which the edges of thick shales and thin interbedded shales appear to be slowly and continuously depleted by the chromatographic processes the composition of the hydrocarbon product accumulating in the reservoirs at this stage appears to be controlled primarily by physical processes rather than by the type and maturity of the organic matter in the generating source rock by this mechanism the origin of accumulations of light oils and gas condensates in low mature sequences bearing predominantly terrestrial derived organic matter can be explained finally the migration effects documented in this study have some consequences for interpretation of geochemical data e g the pristane n c17 ratio a commonly accepted maturity parameter has been shown to be also controlled by the degree of hydrocarbon expulsion

the period and q of the chandler wobble summary we have extended our calculation of the theoretical period of the chandler wobble to account for the non hydrostatic portion of the earth s equatorial bulge and the effect of the fluid core upon the lengthening of the period due to the pole tide we find the theoretical period of a realistic perfectly elastic earth with an equilibrium pole tide to be 426 7 sidereal days which is 8 5 day shorter than the observed period of 435 2 day using rayleigh s principle for a rotating earth we exploit this discrepancy together with the observed chandler q to place constraints on the frequency dependence of mantle anelasticity if q in the mantle varies with frequency u as u between 30 s and 14 months and if q in the lower mantle is of order 225 at 30 s we find that 0 04 5 a 5 0 1 1 if instead q in the lower mantle is of order 350 near 200 s we find that 0 11 5 a 0 19 in all cases these limits arise from exceeding the 68 per cent confidence limits of 2 6 day in the observed period since slight departures from an equilibrium pole tide affect the q much more strongly than the period we believe these limits to be robust

long period tidal factors at antarctica syowa station determined from 10 years of superconducting gravimeter data 1 we determined long period gravimetric tidal parameters from 10 years of superconducting gravimeter observations at syowa station in antarctica the obtained amplitude and phase lead for the mm wave were 6 106 0 030 gal gal 10 8 m s 2 0 32 0 28 respectively and those for the mf wave were 11 657 0 018 gal 0 78 0 09 respectively we also determined the parameters of other tidal constituents with periods of 6 to 32 days mqm msqm mtm mstm msf msm and their frequency dependence was estimated by means of a weighted least squares method the observed values corrected by the four ocean tide models of schwiderski nao 99l fes99 and tpxo6 0 were compared with the theoretical values calculated from the elastic and inelastic solid earth tide models by dehant et al even though the values of the ocean tide corrections have relatively large discrepancies between the four models and it is still difficult to discuss the degree of inelasticity of the earth for this frequency band we can say that the observations favor the inelastic earth model rather than the elastic model

stream incision tectonics uplift and evolution of topography of the sierra nevada california abstract stream incision faulting thermochronologic and geobarometric data suggest that sierra nevada topography is a consequence of two periods of uplift stream incision of up to 1 km has occurred since 5 ma maximum eocene miocene incision was 150 m uplift of the sierra nevada westward tilting stream incision and east down normal and dextral faulting along the present eastern escarpment of the range began at 5 ma estimates of late cenozoic crestal rock uplift for different areas in the sierra nevada range from 1440 to 2150 m low summit erosion rates suggest that the rock uplift approximates the surface uplift of crestal summits tertiary stream gradients were lower than modern ones suggesting that the bottoms of the canyons have been uplifted in the late cenozoic and that the mean elevation of the sierra nevada has increased the elevation of pre cenozoic basement rocks above the base of tertiary paleochannels ranges from 1000 m in the south and

origin and mechanism of the formation of the low oil saturation moxizhuang field junggar basin china implication for petroleum exploration in basins having complex histories the moxizhuang field is a small oil field in the central junggar basin containing several low saturation low resistivity oil reservoirs which display a complex correlation between oil saturation and porosity and permeability that is atypical of both the filled and drained reservoirs biomarker associations of crude oil and grains containing oil inclusions gois of both the present day water bearing zones water zones and the oil and water bearing zones low oil saturation pay zones were analyzed to investigate the mechanisms for the formation of the low saturation low resistivity oil accumulations the biomarker assemblage and hierarchical cluster analysis indicate that oil in the moxizhuang field was mostly generated from permian source rock deposited in brackish to hypersaline anoxic environments the pay zones and several water zones display goi values as much as 38 greater than the generally accepted threshold goi value for an oil column 5 these goi values are similar to those for high saturation oil reservoirs in the bohai bay basin and oil zone samples from australian basins suggesting that both pay zones and water zones were high saturation oil reservoirs in the geologic past geologic history analysis shows that the moxizhuang field was located on the north wing of a paleoanticline during oil charge in the late cretaceous to paleogene this anticline has gradually evolved into a south dipping monocline since the neogene causing northward remigration of accumulated oil differential lateral leakage of accumulated oil in different sandstone layers during the remigration phase led to the formation of the water zones with high goi values completely drained reservoirs and the low saturation low resistivity pay zones partially preserved reservoirs and caused the complex correlation between oil saturation and porosity and permeability compared with other postaccumulation physicochemical alteration processes lateral leakage has rarely been recognized recognizing differential lateral leakage of accumulated petroleum with the existence of high quality unfaulted cap rocks has important implication for petroleum exploration in sedimentary basins having complex evolution histories

tidal gravity and ocean tide loading in europe b the results are presented from tidal gravity measurements at five sites in europe using lacoste and romberg et gravimeters improvements that we have made to the accuracies of these gravimeters are discussed it is shown that the standard calibration of the international center for earth tides used for worldwide tidal gravity profiles is 1 2 per cent too high the m2 and o1 observations are compared with model calculations of the earth s body tide and ocean tide loading and it is shown that there is a very significant improvement in the agreement between observations and models compared to that obtained with previous tidal gravity measurements for o1 where the ocean tide loading and attraction in central europe is only 0 4 per cent of the body tide our measurements verify that the dehant wahr anelastic body tide model gravimetric factor is accurate to 0 2 per cent it is also shown that the effects of lateral heterogeneities in earth structure on tidal gravity are too small to explain the large anomalies in previously published tidal gravity amplitudes the observations clearly show the importance of conserving tidal mass in the schwiderski ocean tide model for sites in central europe the m2 and o1 observations and the models are in agreement at the 0 1 gal 10 9 m s 2 level and tidal corrections to this accuracy can now be made to absolute gravity measurements

two phase westward encroachment of basin and range extension into the northern sierra nevada 1 structural geophysical and thermochronological data from the transition zone between the sierra nevada and the basin and range province at latitude 39 n suggest 100 km westward encroachment of basin and range extensional deformation since the middle miocene extension accommodated primarily by east dipping normal faults that bound west tilted range forming fault blocks varies in magnitude from 150 in the wassuk and singatse ranges to the east geological and apatite fission track data from exhumed upper crustal sections in the wassuk and singatse ranges point to rapid footwall cooling related to large magnitude extension starting at 14 15 ma farther to the west geological and thermochronological data indicate a younger period of extension in the previously unextended pine nut mountains the carson range and the tahoe truckee depression initiated between 10 ma and 3 ma and incipient post 0 5 ma faulting to the west of the tahoe truckee area these data imply the presence of an extensional breakaway zone between the singatse range and the pine nut mountains at 14 15 ma forming the boundary between the sierra nevada and basin and range at that time in addition fission track data imply a miocene preextensional geothermal gradient of 27 5 c km 1 in the central wassuk range and 20 5 c km 1 in the singatse range much higher than the estimated early tertiary gradient of 10 5 c km 1 for the sierra nevada batholith this might point to a significant increase in geothermal gradients coupled with a likely decrease in crustal strength enabling the initiation of extensional faulting apatite fission track geophysical and geological constraints across the sierra nevada basin and range transition zone indicate a two stage coupled structural and thermal westward encroachment of the basin and range province into the sierra nevada since the middle miocene

developments in oil shale in 1988 oil shale development continued at a slow pace in 1988 the continuing interest in this commodity is demonstrated by the 188 oil shale citations added in 1988 to the u s department of energy database and the 122 oil shale papers presented at 2 major oil shale symposia held during 1988

charging of oil fields surrounding the shaleitian uplift from multiple source rock intervals and generative kitchens bohai bay basin china abstract this paper discusses origin and charging directions of oil fields on the shaleitian uplift bohai bay basin the shaleitian uplift is a footwall uplift surrounded by three sags containing mature source rocks the origins of the four oil fields on the shaleitian uplift both in terms of source rock intervals and in terms of generative kitchens were studied using biomarker distributions for 61 source rock samples and 27 oil samples hierarchical cluster analysis using 12 parameters known to be effective indicators of organic matter input and or depositional conditions allowed the identification of six oil types or classes these six oil classes could then be linked to three distinct source rock intervals ranging in age from 43 0 ma to 30 3 ma the third member 43 0 38 0 ma in age and first member 35 8 32 8 ma of the eocene shahejie formation and the third member of the oligocene dongying formation 32 8 30 3 ma each sourced one class of oil the other three classes represent mixtures of oil generated from multiple source rock intervals traps on the shaleitian uplift were charged in the east by oil generated from the eocene shahejie formation in the bozhong sag in the southeast by oil generated from the eocene shahejie and then oligocene dongying formations in the southwestern part of the bozhong sag and or in the eastern part of the shanan sag and in the southwest by oil generated from the eocene shahejie formation in the western part of the shanan sag the estimated migration distances range from less than 5 km to about 20 km the compositional heterogeneity within fields and multiple parameter comparisons between oils from nearby wells in different fields have proven to be a powerful tool to determine the in filling histories of oil fields in cases where multiple source rock intervals and multiple generative kitchens exist

kinematics of the northern walker lane an incipient transform fault along the pacific north american plate boundary in the western great basin of north america a system of dextral faults accommodates 15 25 of the pacific north american plate motion the northern walker lane in northwest nevada and northeast california occupies the northern terminus of this system this young evolving part of the plate boundary offers insight into how strike slip fault systems develop and may reflect the birth of a transform fault a belt of overlapping left stepping dextral faults dominates the northern walker lane offset segments of a w trending oligocene paleovalley suggest 20 30 km of cumulative dextral slip beginning ca 9 3 ma the inferred long term slip rate of 2 10 mm yr is compatible with global positioning system observations of the current strain field we interpret the left stepping faults as macroscopic riedel shears developing above a nascent lithospheric scale transform fault the strike slip faults end in arrays of n striking normal faults suggesting that dextral shear diffuses into extension in the great basin coeval extension and dextral shear have induced slight counterclockwise fault block rotations which may ultimately rotate riedel shears toward the main shear zone at depth thus facilitating development of a throughgoing strike slip fault

deep burial of the footwall of the northern snake range decollement nevada metapelitic eocambrian strata from eastern exposures of the footwall of the northern snake range decollement experienced mesozoic amphibolite facies metamorphism and greenschist facies overprint accompanying extreme ductile thinning samples from the hampton creek area where the overprint is weakest contain the assemblage quartz muscovite biotite garnet plagioclase opaque oxides staurolite kyanite tourmaline apatite textural relations and consistency of rim analyses among multiple domains in each sample indicate equilibrium rim pressure temperature estimates were obtained using the garnet biotite fe mg exchange thermometer and the garnet muscovite plagioclase biotite and garnet aluminosilicate plagioclase barometers the results suggest final equilibration at 610 50 c and 810 70 mpa or a depth of 30 3 km about a factor of 3 greater than the stratigraphic depth to the west in the schell creek range correlative strata are contiguous with unmetamorphosed upper paleozoic and tertiary strata from west to east exposures of eocambrian rocks in the two ranges collectively show increasing intensity of crystal plastic deformation metamorphic recrystallization and metamorphic grade from subgreenschist to amphibolite facies and a monotonic decrease in 40 ar 39 ar muscovite ages from mesozoic age to about 23 ma in light of these relations the pressure temperature data suggest that eocambrian strata were inclined eastward during mesozoic metamorphism with 15 20 km of structural relief we interpret the eastward tilting and burial to be the result of west directed thrusting as expressed by folding to the north in the deep creek range unroofing of the deeply buried strata may have occurred partly in cretaceous or early cenozoic time with final unroofing in oligocene and miocene time along the northern snake range decollement these results exclude the hypothesis that the northern snake range decollement initiated as a brittle ductile transition zone within cambrian strata of a little deformed miogeoclinal section and support the hypothesis that it is a major low angle extensional shear zone

long period tides observed with a superconducting gravimeter at syowa station antarctica and their implication to global ocean tide modeling abstract the long period tides mf and mm waves were analyzed with the 2 years data obtained with a superconducting gravimeter sg installed at syowa station 69 0 s 39 6 e antarctica the observed amplitudes phase lags and amplitude factors factors were 11 642 0 035 gal 0 12 0 17 and 1 1218 0 0034 for the mf wave and 6 143 0 058 gal 0 33 0 54 and 1 1205 0 0106 for the mm wave respectively 1 gal 10 8 m s 2 the ocean tide effects effects of the attraction and loading due to the ocean mass at the observation site were estimated using the five global ocean tide models equilibrium ocean tide model schwiderski model schwiderski e w 1980 on charting global ocean tides rev geophys space phys 18 243 268 dickman model dickman s r 1989 a complete spherical harmonic approach to luni solar tides geophys j int 99 457 468 csr model eanes r j 1995 private communication and desai and wahr model desai s h wahr j m 1995 empirical ocean tide models estimated from topex poseidon altimetry j geophys res 100 25205 25228 the averages of the five estimates are 0 433 gal and 0 244 gal in amplitude and 192 9 and 179 5 in phase for the mf and mm waves respectively the five estimates differ by a maximum of 0 104 gal in amplitude and 18 8 in phase for the mf wave and by 0 033 gal and 6 4 for the mm wave the estimated mm phases are nearly 180 for the five models and the variation of their values among the models is relatively small compared with that of the mf phases these indicate that the mm wave is much closer to an equilibrium tide than the mf wave due to the variation of the ocean tide corrections the corrected factors were scattered within the ranges of 1 158 to 1 169 for the mf wave and of 1 163 to 1 169 for the mm wave however it is noted that the mean factors of the five ocean models i e 1 162 0 023 for the mf wave and 1 165 0 014 for the mm wave prefer slightly larger value rather than those estimated from the theory of the elastic tide

a new test of earth tide models in central europe new improved ocean tide models allow a corresponding improvement in ocean tide loading computations during recent years various groups have made more accurate tidal gravity observations in central europe using gravimeters carefully calibrated on various calibration lines this progress with tidal gravity measurements and ocean loading corrections now allows a more comprehensive test of body tide models than was possible previously it is shown that the o1 and m2 gravimetric factors corrected using the latest ocean tide models are very consistent between the sites despite the different instruments and gravity calibration lines that have been used these observations allow constraints to be put on the anelasticity of the earth at tidal frequencies the corrected gravimetric factors are consistent with recent model results for both the elastic prem model and with 0 09 for an anelastic prem model with the q for dissipation in shear varying as frequency to the power

thermochronometrically constrained anatomy and evolution of a miocene extensional accommodation zone and tilt domain boundary the southern wassuk range nevada 1 apatite ahe and zircon zhe u th he thermochronometric data from the southern wassuk range wr coupled with 40ar 39ar age data from the overlying tilted tertiary section are used to constrain the thermal evolution of an extensional accommodation zone and tilt domain boundary ahe and zhe data record two episodes of rapid cooling related to the tectonic exhumation of the wr fault block beginning at 15 and 4 ma extension was accommodated through fault block rotation and variably tilted the southern wr to the west from 60 70 in the central wr to 15 35 in the southernmost wr and pine grove hills and minimal tilting in the anchorite hills and along the mina deflection to the south middle miocene geothermal gradient estimates record heating immediately prior to large magnitude extension that was likely coeval with the extrusion of the lincoln flat andesite at 14 8 ma geothermal gradients increase from 19 4 c km to 65 20 c km toward the mina deflection suggesting that it was the focus of middle miocene arc magmatism in the upper crust the decreasing thickness of tilt blocks toward the south resulted from a shallowing brittle ductile transition zone postmagmatic middle miocene extension and fault block advection were focused in the northern and central wr and coincidentally moderated the large lateral thermal gradient within the uppermost crust

a parametrized solid earth tide model and ocean tide loading effects for global geodetic baseline measurements summary an observation model for earth tide displacements in application to very long baseline interferometry and similar precise geodetic techniques is developed it incorporates effects from anelasticity ellipsoidal figure and fluid core resonance based on a harmonic development of the external potential the model follows the familiar love number concept the transfer function of the earth to each harmonic is formulated in terms of coupled harmonics in the space domain and fulfils the causality condition in the time domain solve for parameters can be chosen flexibly the guideline however has been to provide a minimum set of well defined and well resolvable tide response parameters for analysis of observations the aim of accuracy for tide displacements prediction is below 1 mm being the major perturbation of the solid earth tide ocean tide loading effects are computed and the accuracy of the models involved is discussed it appears that the major error source relates to those ocean tide frequencies for which global models are not available these frequencies form a continuum with a power spectrum being largely a result of non linear tide interaction the associated loading effects cannot be reliably interpolated from global tide models which are available only for a few distinct frequencies and which disregard tidal intermodulation thus an accuracy of 1 mm for computed loading tide displacements cannot always be achieved

deposition diagenesis and maturation of organic matter in rift basin lacustrine shales of triassic jurassic newark supergroup evaluating the petroleum source potential of rift basins in frontier areas is difficult because rift lakes vary greatly in areal extent water depth water chemistry and longevity in addition climatic cycles are often strongly expressed in lacustrine settings triassic jurassic deposits in the continental rift basins on the atlantic margin of north america are one of the few cases where lateral and vertical variations in the content c sub org hydrogen index and thermal maturity t sub max r sub 0 of bulk organic matter are well documented relatively little is known however about sulfur content s sub org s sub total and the composition of biomarkers in these strata new data on low maturity shales r sub o 0 4 in the jurassic portion of the hartford basin show wide variation in s sub total c sub org ratios suggesting that paleolimnological conditions ranged from fresh to alkaline or saline stratigraphic profiles of c sub org and s sub total through individual shale beds indicate rapid and repeated changes in water chemistry during each lacustrine cycle bitumens extracted from samples with less than about 0 05 s sub total are characterized by dominance or high abundance of carotanes and extended regular isoprenoids in the saturated hydrocarbons these biomarkers are probably derived from carotenoid pigmentsmore of algae or bacteria early diagenesis in the absence of hydrogen sulfide may account for the unusual preservation of extended isoprenoids and carotanes in the bitumen less

the pristane n heptadecane ratio as an indicator for recognition of hydrocarbon migration effects a simple scheme is proposed for type iii kerogen source rocks which uses pristane n heptadecane concentration ratios for recognition of hydrocarbon expulsion effects within the maturity interval 0 82 1 03 rm this scheme can be applied from gas chromatography data routinely obtained by most petroleum geochemistry studies in exploration exploration of this scheme to oil prone type ii source rocks appears very promising

thrust timing growth of structural culminations and synorogenic sedimentation in the type sevier orogenic belt western united states most of the regional shortening in the type area of the sevier orogenic belt in central utah was accommodated by displacement on the canyon range neocomian aptian pavant aptian albian paxton cenomanian campanian and gunnison late campanian paleocene thrust systems inception of each thrust system generated synorogenic sediment associated with frontal thrust tip anticlines or triangle zones and older thrust sheets that were elevated above major ramps farther toward the hinterland the sevier culmination a large antiformal duplex cored by crystalline basement rocks developed during paxton and gunnison thrusting west of and structurally beneath the canyon range and pavant thrusts growth of the sevier culmination was coeval with reactivation of the canyon range and pavant thrust systems and produced a second culmination in proterozoic lower cambrian rocks in the canyon range these structural highs provided much of the sediment to the adjacent foreland basin from late cenomanian to late paleocene time and may have helped to maintain critical taper in the thrust belt

a hot and high eocene sierra nevada despite broad interest in determining the topographic and climatic histories of mountain ranges the evolution of california s sierra nevada remains actively debated prior stable isotope based studies of the sierra nevada have relied primarily on hydrogen isotopes in kaolinite hydrated volcanic glass and leaf n alkanes here we reconstruct the temperature and elevation of the early eocene sierra nevada using the oxygen isotope composition of kaolinitized granite clasts from the ancestral yuba and american rivers that drained the windward pacific flank of the sierra nevada first we evaluated the possible contributions of hydrogen isotope exchange in kaolinite by direct comparison with oxygen isotope measurements next we utilized differences in the hydrogen and oxygen isotope fractionation in kaolinite to constrain early eocene midlatitude weathering temperatures oxygen isotope geochemistry of in situ kaolinites indicates upstream eastward depletion of 18o in the northern sierra nevada the 18o values ranging from 11 4 to 14 4 at the easternmost localities correspond to paleoelevations as high as 2400 m when simulating the orographic precipitation of moisture from a pacific source using eocene boundary conditions this result is consistent with prior hydrogen isotope studies of the northern sierra but oxygen isotope based paleoelevation estimates are systematically 500 1000 m higher than those from hydrogen based estimates from the same samples kaolinite geothermometry from 16 samples produced early eocene weathering temperatures of 13 0 36 7 c with an average of 23 2 6 4 c 1 these kaolinite temperature reconstructions are in general agreement with paleofloral and geochemical constraints from eocene california localities and climate model simulations our results confirm prior hydrogen isotope based paleoelevation estimates and further substantiate the existence of a hot and high eocene sierra nevada