the q structure of the upper mantle constraints from rayleigh wave amplitudes 1 the three dimensional shear attenuation or q structure of the upper mantle is still poorly understood despite the increasing accuracy and sophistication of velocity models of the same part of the earth here we present a set of three dimensional q models of the upper mantle based on amplitude measurement of minor and major arc rayleigh waves in the period range 70 170 s the models show that areas of low attenuation underlie continents to a depth of around 300 km and areas of high attenuation are associated with oceans and plate boundaries particularly in the top 200 km below 350 km the sensitivity of the data to attenuation structure decreases rapidly it is well known that the amplitudes of surface waves can be strongly influenced by factors other than attenuation in particular focusing due to elastic structure and errors in source mechanisms we consider the effects of focusing by discussing the implications of the results of selby and woodhouse 2000 comparisons with focusing predictions using phase velocity maps allow us to identify features due to focusing in maps of attenuation distribution the influence of the source on the observed attenuation distribution is investigated by including a source term in the model inversion we find that successfully combining the data at each frequency into one three dimensional model requires that this source term must vary with frequency suggesting that a simple correction to the scalar moment of each event cannot explain the observations although the effects of focusing and the source can be significant we find that the observed attenuation pattern is robust up to degree 8 however shorter wavelength structure can be strongly influenced by other controls finally we use one of the models to predict the degree 2 attenuation pattern for 250 s rayleigh waves the observed pattern suggests that existing normal mode observations may be explainable in terms of structure above 350 km depth

seismic tomography a window into deep earth abstract the goal of this paper is to provide an overview of the current state of the art in seismic tomography and trace its origins from pioneering work in the early 1970s to its present status as the pre eminent tool for imaging the earth s interior at a variety of scales due to length limitations we cannot hope to cover every aspect of this diverse topic or include mathematical derivations of the underlying principles rather we will provide a largely descriptive coverage of the methodology that is targeted at readers not intimately familiar with the topic the relative merits of local versus global parameterization ray tracing versus wavefront tracking backprojection versus gradient based inversion and synthetic testing versus model covariance are explored a variety of key application areas are also discussed including body wave traveltime tomography surface wave tomography attenuation tomography and ambient noise tomography established and emerging trends many of which are driven by the ongoing rapid increases in available computing power will also be examined including finite frequency tomography full waveform tomography and joint tomography using multiple datasets several practical applications of seismic tomography including body wave traveltime attenuation and surface waveform are presented in order to reinforce prior discussion of theory

the meandering gulf stream as seen by the geosat altimeter surface transport position and velocity variance from 73 to 46 w the surface geostrophic velocity field for the gulf stream region was analyzed for the position structure and surface transport of the gulf stream for 2 5 years of the geosat altimeter exact repeat mission synthetic data using a gaussian velocity profile were generated and fit to the sea surface residual heights to create a synthetic mean sea surface height field and profiles of absolute geostrophic currents most of cross track velocity variance was due to the meandering of the gulf stream rather than to rings or complicated velocity profiles which suggested that the simple model parameters are an efficient description of the gulf stream fluctuations an analysis of the model parameters and the actual geostrophic velocity profiles revealed two different flow regimes for the gulf stream connected by a narrow transition region coincident with the new england seamount chain the upstream region was characterized by relatively straight gulf stream paths long eulerian time scales and eastward propagating meanders the downstream region had more large meanders no consistent propagation direction and shorter eulerian time scales a 25 reduction in surface transport occurred in the transition region with a corresponding reduction in current speed and no change in gulf stream width a significant anomaly in surface transport near 69 w suggested the existence of small scale recirculation gyres there the highest variance empirical orthogonal functions of position and surface transport were significantly correlated with larger surface transports leading more northerly positions by a month

comparisons between measurements and predictions of rayleigh wave amplification across the contiguous united states abstract we present local surface wave amplification maps spanning the contiguous united states for rayleigh waves between 35 s and 125 s using data recorded on the usarray between 2006 and 2015 we isolate the effect of local structure from those of the earthquake and propagation using a previously developed method based on ratios of amplitudes measured at adjacent stations to assess the ability of our technique to resolve surface wave amplification we perform a parallel synthetic tomography experiment we determine amplification from a large dataset of specfem synthetic seismograms calculated for usarray stations and compare the measurements with direct predictions of local amplification correlations between synthetic and predicted amplification are high with correlation coefficients ranging from 0 77 at 40 s to 0 95 at 100 s indicating that we are able to resolve well local variations in amplification particularly at long periods the remaining differences between synthetic and directly predicted amplification maps suggest the influence of finite frequency effects on surface wave amplitudes observed rayleigh wave amplification factors reflect local elastic structure in the region surrounding each station and could be used as a complementary constraint to image the structure of the earth s crust and upper mantle

synthetic fluid inclusions xvii pvtx properties of high salinity h2o nacl solutions 30 wt nacl application to fluid inclusions that homogenize by halite disappearance from porphyry copper and other hydrothermal ore deposits fluid inclusions that homogenize by disappearance of the halite crystal after the vapor bubble has disappeared have been reported from a wide range of ore forming systems while this inclusion type is most commonly observed in porphyry copper and similar magmatichydrothermal ore deposits they have also been reported from iron oxide copper gold iocg mississippi valley type orogenic lode greenstone gold massive sulfide unconformity u and mantotype deposits as well as from non ore associated granitoids and oceanic crust the lack of experimental data to interpret microthermometric data from these inclusions combined with poor petrographic characterization of inclusion origin has led to a wide range of inferred pt trapping conditions for the inclusions the relationship between liquid vapor homogenization temperature thl v halite dissolution temperature tmhalite and pressure has been determined using synthetic h2o nacl fluid inclusions that homogenize by halite disappearance the experimental data cover the range thl v 150 to 500 c and tmhalite 275 to 550 c an empirical equation describing the relationship between pressure thl v and tmhalite has been developed to estimate formation pressures from microthermometric data and is valid from pressures along the liquid vapor halite curve to 300 mpa a detailed literature review reveals that the results of this study cannot be applied retroactively to estimate pressures of previously reported inclusions that homogenize by halite dissolution for several reasons first most workers have not collected and reported the data in a manner that allows one to determine if the inclusions have trapped a single homogeneous phase and have not leaked or changed volume following trapping thus it is not possible to determine if the inclusions show consistent microthermometric behavior within a group of coeval inclusions additionally many published studies provide only summaries of results from numerous samples or present the data graphically precluding application of our results to individual inclusions however based on our review it appears that much of the published data for inclusions that homogenize by halite dissolution represent inclusions that have either trapped a halite crystal along with the liquid or have reequilibrated by necking and or stretching results from this study have been used to estimate minimum formation pressures for inclusions from the ditrau alkaline massif transylvania romania the musoshi stratiform copper deposit zaire the bismark skarn deposit northern mexico the naica chimneymanto deposit mexico the questa porphyry molybdenum deposit new mexico and the bingham canyon porphyry cu mo deposit utah in each case pressures estimated using results from the present study are in good agreement with previous pressure estimates however in some cases estimated pressures both our estimates as well as those of other authors appear to be unreasonably high based on the geologic setting at the time of formation these results highlight the currently limited understanding concerning pressures depths of ore formation

radial qμ structure of the lower mantle from teleseismic body wave spectra abstract we have measured 150 000 p and 130 000 s wave spectral ratios up to 0 8 hz using recordings of 250 deep focal depth 200 km earthquakes from 890 global and regional network stations we have inverted these data to estimate the attenuation parameters t p and t s for p and s waves and a radial profile of the quality factor q for the lower mantle on average t p increases by about 0 2 s and t s increases by about 0 7 s between epicentral distances of 30 and 97 the relatively strong increase of t s t s 4t p suggests that intrinsic shear attenuation is the cause of the overall trend in our data the increase of t p and t s with distance is smaller than predicted by models prem 12 ql6 11 and qlm9 16 assuming prem values for q in the upper mantle where the data lack resolving power the p and s wave spectra are explained best if q increases from about 360 at prem s 670 km discontinuity to 670 in the lowermost mantle the high values for q can be reconciled with previously determined values by invoking a frequency dependence of q that is proportional to 0 1 data that are separated in pacific and circum pacific subsets have slightly different trends estimates of t p and t s for the pacific data which sample the large low shear velocity province of the pacific are higher than the circum pacific estimates thus it appears that the pacific large low shear velocity province has accompanying low q the difference in q in the lowermost 1000 km of the mantle beneath the pacific and beneath the circum pacific is at most 17 lateral variations of this magnitude are marginally resolvable given the uncertainties of our measurements

near real time simulations of global cmt earthquakes summary we have developed a near real time system for the simulation of global earthquakes prompted by a trigger from the global centroid moment tensor cmt project the system automatically calculates normal mode synthetic seismograms for the preliminary reference earth model and spectral element synthetic seismograms for 3 d mantle model s362ani in combination with crustal model crust2 0 the 1 d and 3 d synthetics for more than 1800 seismographic stations operated by members of the international federation of digital seismograph networks are made available via the internet global shakemovie princeton edu and the incorporated research institutions for seismology data management center iris iris edu the record length of the synthetics is 100 min for cmt events with magnitudes less than 7 5 capturing r1 and g1 at all epicentral distances and 200 min for cmt events with magnitudes equal to or greater than 7 5 capturing r2 and g2 the mode simulations are accurate at periods of 8 s and longer whereas the spectral element simulations are accurate between periods from 17 to 500 s the spectral element software incorporates a number of recent improvements for example the mesh honours the moho as a first order discontinuity underneath the oceans and continents and the performance of the solver is enhanced by reducing processor cache misses and optimizing matrix matrix multiplication in addition to synthetic seismograms the system produces a number of earthquake animations as well as various record sections comparing simulated and observed seismograms

the role of h 2 o in rapid emplacement and crystallization of granite pegmatites resolving the paradox of large crystals in highly undercooled melts granite pegmatite sheets in the continental crust are characterized by very large crystals there has been a shift in viewing pegmatites as products of very slow cooling of granite melts to viewing them as products of crystal growth in undercooled liquids with this shift there has been a renewed debate about the role of h2o in the petrogenesis of pegmatites based on data on nucleation of minerals and new viscosity models for hydrous granite melts it is argued that h2o is the essential component in the petrogenesis of granite pegmatites h2o is key to reducing the viscosity of granite melts which enhances their transport within the crust it also dramatically reduces the glass transition temperature which permits crystallization of melts at hundreds of degrees below the thermodynamic solidus which has been demonstrated by fluid inclusion studies and other geothermometers published experimental data show that because h2o drastically reduces the nucleation rates of silicate minerals the minerals may not be able to nucleate until melt is substantially undercooled in a rapidly cooling intrusion nucleation starts at its highly undercooled margins followed by inward crystal growth towards its slower cooling hotter core delay in nucleation may be caused by competition for crystallization by several minerals in the near eutectic melts and by the very different structures of minerals and the highly hydrated melts once a mineral nucleates however it may grow rapidly to a size that is determined by the distance between the site of nucleation and the point in the magma at which the temperature is approximately that of the mineral s liquidus assuming components necessary for mineral growth are available along the growth path granite pegmatites are apparently able to retain h2o during most of their crystallization histories within the confinement of their wall rocks pegmatitic texture is a consequence of delayed nucleation and rapid growth at large undercooling both of which are facilitated by high h2o li b f and p contents in granite pegmatite melts without retention of h2o the conditions for pegmatitic textural growth may be difficult to achieve loss of h2o due to decompression and venting leads to microcrystalline texture and potentially glass during rapid cooling as seen in rhyolites in contrast slow cooling within a large magma chamber promotes continuous exsolution of h2o from crystallizing magma growth of equant crystals and final solidification at the thermodynamic solidus these are the characteristics of normal granites that distinguish them from pegmatites

evolution from magmatic to hydrothermal activity beneath the cerro escorial volcano nw argentina as sampled by erupted quartz and brines abstract large quartz pebbles erupted with the escorial ignimbrite provide insight into the late magmatic evolution of the shallow cooling magmatic hydrothermal system below the cerro escorial volcano of the southern central volcanic zone in the argentine andes the ignimbrite is of relatively small volume crystal rich dacitic in composition and not particularly water rich as amphibole is absent eruption temperature was estimated to be close to 850 c the quartz pebbles provide insight into the magmatic hydrothermal transition beneath the volcano based on textures trace element composition analyzed by laser ablation inductively coupled plasma mass spectrometry and inclusion content the pebbles can be separated into pegmatite like megacrysts and lower temperature epithermal microcrystalline quartz both types are distinct from magmatic phenocrysts present in porphyritic clasts ejected by the ignimbrite the megacrysts show a wide range of trace element concentrations with elevated al concentrations and al ti and ge ti ratios compared to quartz phenocrysts although some contamination by submicroscopic inclusions and cooling to near solidus temperatures may perturb the signal in some cases the range of trace element concentrations in quartz crystals from this system may reflect a change in crystallization conditions from initial precipitation from typical evolved silicate melt to fast growth from residual melt and or fluid in pegmatitic pockets or coarse grained hydrothermal veins at locally variable precipitation conditions abundant primary and secondary silicate melt inclusions and a variety of secondary fluid inclusions are present within the megacrysts in particular brine inclusions are densely packed with salt crystals sometimes anhydrite and or a silicate crystal but no visible liquid at room temperature and co existing vapor inclusions are of very low density heating experiments of brine inclusions reveal last salt and vapor bubble dissolution temperatures around 600 700 c but an immiscible silicate melt surrounding the homogenized salt globule remains even at unreasonably high temperature the co existence of silicate melt and fluid inclusions reinforces the magmatic nature of the fluids while boiling trails of brine with cu concentrations of several percent and vapor point to relatively low pressures

earthquake ground motion amplification for surface waves surface waves from earthquakes are known to cause strong damage especially for larger structures such as skyscrapers and bridges however common practice in characterizing seismic hazard at a specific site considers the effect of near surface geology on only vertically propagating body waves here we show that surface waves have a unique and different frequency dependent response to known geologic structure and that this amplification can be analytically calculated in a manner similar to current hazard practices applying this framework to amplification in the los angeles basin we find that peak ground accelerations for certain large regional earthquakes are underpredicted if surface waves are not properly accounted for and that the frequency of strongest ground motion amplification can be significantly different including surface wave amplification in hazards calculations is therefore essential for accurate predictions of strong ground motion for future san andreas fault ruptures

is quartz cathodoluminescence color a reliable provenance tool a quantitative examination abstract we examined cathodoluminescence cl colors of quartz by using red 590 780 nm green 515 590 nm and blue 380 515 nm optical filters interfaced with a cathodoluminescence cl detector attached to a scanning electron microscope sem sem cl images taken through these filters were captured digitally and transferred to a computer luminescence intensities luminosities of the images were measured by using available commercial software measured luminosities of these cl images are directly related to relative intensities of red green and blue cl emissions luminosity data were then used to construct plots that display relative luminosities of the cl images acquired through the red green and blue filters an unfiltered cl image of each quartz grain generated by photons with wavelengths ranging from 200 700 nm was also acquired by subtracting the numerical luminosity values of the images acquired through the red green and blue filters from the luminosity value of the unfiltered image the contribution to total luminosity provided by cl emission in the near ultraviolet uv was calculated the cl colors of quartz from a variety of volcanic plutonic and metamorphic rocks and hydrothermal deposits were examined volcanic quartz phenocrysts have the most restricted cl color range with strongest emission intensity in the blue wavelength band cl colors of plutonic quartz overlap those of volcanic phenocrysts but extend over a broader range to include quartz that displays higher intensity of red emission cl emission in hydrothermal vein quartz is similar to that in plutonic quartz although some hydrothermal quartz exhibits stronger green cl emission than does plutonic quartz the cl colors of metamorphic quartz exhibit the widest variation overlapping the color fields of both volcanic and plutonic quartz and extending further into the red cl emission in the near uv makes a significant contribution 5 85 percent to the total luminosity of sem cl images particularly images of plutonic quartz because of overlap in the cl color ranges of volcanic plutonic metamorphic and hydrothermal quartz unambiguous identification of quartz provenance on the basis of cl color alone is problematic it is difficult to distinguish between volcanic and some plutonic quartz and between some plutonic and hydrothermal quartz or to distinguish magmatic quartz from metamorphic quartz that exhibits blue cl color only metamorphic quartz that exhibits moderately strong red emission appears distinguishable on the basis of color from quartz of other origins our work thus suggests that cl color is not a reliable indicator of quartz provenance

normal modes and long period seismograms in a 3d anelastic elliptical rotating earth 1 we present results of a direct method to compute realistic long period 200 s in this example synthetic seismograms using higher order perturbation theory up to the 3rd order normal modes are computed for the earth taking into account rotation ellipticity 3d elastic lateral heterogeneities saw12d for the whole mantle and anelastic lateral variations in the upper mantle qr19 coupling between different modes and branches is included in the computation we study the sensitivity of the waveform to 3d anelasticity and the biases between 3d elastic and 3d anelastic variations the resulting seismograms can be computed to higher frequency and may then be used to perform whole mantle joint inversions for elastic and anelastic structure

extreme fractionation in a granite pegmatite system documented by quartz chemistry the case study of tres arroyos central iberian zone spain abstract the tres arroyos granite pegmatite system is located in the sw margin of the nisa alburquerque variscan batholith two granitic facies monzogranite and marginal leucogranite and three types of aplite pegmatite dykes barren intermediate and highly evolved li rich have been distinguished in the area with a zoned distribution from the granite southwards trace elements in quartz from the five facies have been analysed by la icp ms in order to obtain information about the petrogenetic links among the different lithologies of this system as well as to better understand the regional and individual fractionation processes that led to the distinct rocks aluminium ti li and ge show continuous trends from the monzogranite through the marginal granitic facies the barren and intermediate aplite pegmatites up to the most evolved li rich dykes titanium and ge contents respectively decrease and increase gradually with fractionation in contrast al and li show a more complex trend with an initial descending trend to the marginal granitic facies and then showing the highest al and li contents in the quartz from the most fractionated li rich aplite pegmatites this suggests the influence of different competing factors controlling the incorporation of these trace elements in quartz such as the chemical composition of the melt the p and t conditions and the rate of crystallization based on the good correlation between al and li the substitution si4 al3 li seems to be the dominant mechanism of li incorporation into quartz the negligible amount of other trace elements suggests that the remaining al was mainly compensated with h ions via the si4 al3 h substitution a continuous fractionation trend from the monzogranite up to the most fractionated aplite pegmatites is inferred from geochemical modelling by applying the rayleigh equation for fractional crystallization fractionation rates over 50 are needed to obtain the marginal granite and the barren aplite pegmatites compositions and over 99 for the most evolved dykes no pattern in the chemical variation of the trace elements in quartz from different layers in the layered aplite pegmatites has been found suggesting the lack of internal fractionation processes most probably due to the rapid crystallization of the pegmatitic melt intruded into a colder country rock

upper mantle s velocity structure of central and western south america we have used broadband seismograms recorded at portable and permanent seismic stations in south america to image the three dimensional s velocity structure beneath central and western south america we have interactively fitted the waveforms of s and surface wave trains in 500 seismograms from 90 earthquakes and 60 different stations the constraints on upper mantle s velocity structure provided by the waveform fits have been combined with independent estimates of depth to the mohorovicic discontinuity yielding model sa99 the s velocity structure of sa99 reveals a highly heterogeneous upper mantle with a maximum peak to peak difference of 1 km s above 100 km the heterogeneity seems to be correlated with tectonic and geologic domains sa99 shows high lithospheric s velocities for the precambrian cratons the amazon basin is also underlain by high s velocities while three other intraplatform basins are underlain by low s velocities at various depths sa99 shows extremely low velocities in the mantle wedge beneath the volcanically active andes we explain these low s velocities as originating from realistic amounts of volatiles released by the subducting nazca crust and resulting amounts of partial melt within the peridotitic mantle wedge without requiring elevated temperatures while sa99 could be consistent with diffuse influx for corner flow in the mantle wedge it does not support models that require influx of subcontinental upper mantle into the mantle wedge through a laterally uniform low viscosity channel

global maps of rayleigh wave attenuation for periods between 40 and 150 seconds studies of seismic attenuation must account for the large amplitude deviations caused by elastic focusing of energy in a new approach we jointly invert phase and amplitude measurements of 19 000 minor arc rayleigh waves between periods of 40 and 150 seconds the simultaneous inversion ensures that attenuation and phase velocity are mutually consistent because the phase and focusing term of amplitude are modelled using a common elastic model at the shortest periods the maps show a good correlation between attenuation and phase velocity suggesting a common cause in the uppermost mantle most probably thermal in origin this correlation is lost at longer periods the main signal beyond periods of 100 seconds is a strongly attenuating circum pacific zone and a pronounced ring of high attenuation around africa this feature seems reliable in our attenuation maps but not correlated to an equivalent structure in phase velocity we thus favour scattering of wave energy on large size structures as a possible cause

upper mantle attenuation and velocity structure from measurements of differential s phases summary although much progress has been made in determining the 3 d distribution of seismic wave velocities in the earth substantially less is known about the 3 d distribution of intrinsic attenuation in this study variations in attenuation and shear velocity of the earth s mantle are constrained using measurements of differential traveltime and attenuation the data are broad band displacement sh seismograms filtered to have energy in the period range 8 20 s the seismograms are obtained from over 600 globally distributed earthquakes of magnitude mw 5 5 or greater differential traveltimes and differential t values from multiple s phases are estimated by a waveform fitting method resulting in approximately 4300 measurements for ss s in the distance range 50u 105u and 1000 measurements for sss ss in the distance range 90u 179u each measurement consists of a differential traveltime and a corresponding differential t the differential traveltimes and t values are inverted to obtain models of the lateral variation of shear velocity and lateral variation of qm where qm 1 qm the models explain the data well but have limited depth resolution the velocity models show good correlation with previous studies in particular low velocities are observed underlying mid oceanic ridges and convergent margins and high velocities are found for continental regions the qm models show shield regions to be less attenuating than prem with ridges appearing as highly attenuating features the models have limited depth resolution and to address this problem we also present a shear velocity model obtained from the combination of body wave and surface wave data sets

diversity of primary cl textures in quartz from porphyry environments implication for origin of quartz eyes porphyry style mineralization is related to the intrusion and crystallization of small stocks which can be of different compositions from intermediate to felsic and can intrude into different host rocks from magmatic to sedimentary we used cathodoluminescence and electron probe microanalysis to study the internal textures of more than 300 quartz eyes from six porphyry deposits panguna papua new guinea far southeast porphyry philippines batu hijau indonesia antapaccay peru rio blanco chile and climax usa significant diversity of the internal textures in quartz eyes was revealed sometimes even within a single sample quartz grains with ti rich cores surrounded by ti poor mantles were found next to the grains showing the opposite ti distribution or only slight ti fluctuations we propose that diversity of the internal patterns in quartz eyes can actually reflect in situ crystallization history and that prolonged crystallization after magma emplacement under conditions of continuous cooling can account for the observed features of internal textures formation of quartz eyes begins at high temperatures with crystallization of high titanium quartz 1 which as the melt becomes more and more evolved and cooler is overgrown by low ti quartz 2 subsequent fluid exsolution brings about dramatic change in the melt composition oh alkalis and other cl complexed elements partition into the fluid phase whereas ti stays in the melt contributing to a rapid increase in ti activity separation of the fluid and its further cooling causes disequilibrium in the system and the quartz 2 becomes partially resorbed exsolution of the fluid gradually builds up the pressure until it exceeds the yield strength of the host rocks and they then fracture this pressure release most likely triggers crystallization of quartz 3 which is higher in ti than quartz 2 because ti activity in the melt is higher and pressure of crystallization is lower as a result of the reaction between the exsolved fluid and quartz a new phase a so called heavy fluid forms from this phase quartz 4 crystallizes this phase has extremely high metal carrying capacity and may give a rise to mineralizing fluids finally on the brink of the subsolidus stage groundmass quartz crystallizes prolonged crystallization under conditions of continuous cooling accounts better for the diversity of cl textures than crystallization in different parts of a deep magma chamber it is also in a better agreement with the existing model for formation of porphyry style deposits

degree 2 pattern of attenuation structure in the upper mantle from apparent complex frequency measurements of fundamental spheroidal modes the authors present preliminary results of an analysis of global lateral variations in elastic and anelastic structure of the upper mantle using the sompi method they have analyzed ida records to measure apparent complex frequencies of fundamental spheroidal modes sub 0 s sub 21 sub 0 s sub 34 which are primarily sensitive to the structure of the transition zone the apparent complex frequencies have then been inverted into local frequency and attenuation maps using the new inversion method the authors have obtained consistent degree 2 patterns in the local attenuation maps as well as in the local frequency maps the high attenuation anomalies correlate with regions of slow p wave velocity in the lower mantle and with regions of high hotspot density this may represent a continuation of lower mantle upwelling into the transition zone

u pb geochronology of hydrothermal zircons from the early cretaceous iron skarn deposits in the handan xingtai district north china craton the handan xingtai district in the north china craton is one of the most important concentrations of iron skarn deposits in china with proven reserves of 900 to 1 000 mt at an average of 40 to 55 wt fe the iron mineralization occurs predominantly along contact zones between early cretaceous intermediate silicic intrusions and middle ordovician marine carbonates intercalated with numerous evaporite beds in this paper we present textural features and laser ablation icp ms u pb dating results of hydrothermal zircon from five major iron skarn deposits to place tight constraints on the timing and duration of the district scale iron mineralization zircon grains from the mineralized skarns are anhedral to subhedral crystals and euhedral tetragonal bipyramids they are closely intergrown or texturally associated with diopside garnet epidote calcite albite and phlogopite other common minerals in the skarn assemblages include f rich hornblende wilkeite f f apatite and fluorite zircon grains typically contain abundant inclusions of skarn minerals and daughter mineral rich mostly magnetite halite and sylvite fluid inclusions compositionally these zircon grains have moderately to extremely high th 518 7 477 ppm and u 109 25 610 ppm contents with highly variable th u ratios ranging from 0 01 to 5 23 the morphological textural and geochemical features of the zircons confirm their hydrothermal origin and indicate that they most likely precipitated from high temperature f rich magmatic derived ore forming fluids the hydrothermal zircon grains yield well defined concordant u pb ages for the five studied iron skarn deposits with weighted mean 206 pb 238 u dates ranging from 133 6 0 9 to 128 5 1 4 ma 2 these ages are remarkably consistent with u pb ages 134 1 1 2 to 128 5 0 9 ma 2 of magmatic zircon grains from the ore related intrusions in each deposit demonstrating that iron skarn mineralization was genetically related to the coeval magmatism our new geochronological data when combined with existing isotopic ages indicate that iron mineralization and associated magmatism in the handan xingtai district took place mainly at the ca 137 133 and 131 128 ma intervals iron skarn deposits of similar ages also occur widely in other parts of the eastern north china craton forming the only known giant mesozoic iron skarn province in a cratonic block on the earth the formation of these iron skarn deposits and associated intrusions coincided in time with lithospheric thinning or destruction of the north china craton strongly suggesting a causal link between the two processes

anisotropic shear wave velocity structure of the earth s mantle a global model 1 we combine a new large data set of surface wave phase anomalies long period waveforms and body wave travel times to construct a three dimensional model of the anisotropic shear wave velocity in the earth s mantle our modeling approach is improved and more comprehensive compared to our earlier studies and involves the development and implementation of a new spherically symmetric reference model simultaneous inversion for velocity and anisotropy as well as discontinuity topographies and implementation of nonlinear crustal corrections for waveforms a comparison of our new three dimensional model s362ani with two other models derived from comparable data sets but using different techniques reveals persistent features 1 strong 200 km thick high velocity anomalies beneath cratons likely representing the continental lithosphere underlain by weaker fast anomalies extending below 250 km which may represent continental roots 2 weak velocity heterogeneity between 250 and 400 km depths 3 fast anomalies extending horizontally up to 2000 3000 km in the mantle transition zone beneath subduction zones 4 lack of strong long wavelength heterogeneity below 650 km suggesting inhibiting character of the upper mantle lower mantle boundary and 5 slow velocity superplumes beneath the pacific and africa the shear wave radial anisotropy is strongest at 120 km depth in particular beneath the central pacific lateral anisotropic variations appreciably improve the fit to data that are predominantly sensitive to the uppermost and lowermost mantle but not to the waveforms that control the transition zone and midmantle depths tradeoffs between lateral variations in velocity and anisotropy are negligible in the uppermost mantle but noticeable at the bottom of the mantle

global models of surface wave attenuation 1 a large data set of fundamental mode rayleigh wave amplitudes is analyzed to derive global models of surface wave attenuation 1 q the data set consists of measurements of rayleigh wave amplitude anomalies in the period range 50 250 s for 347 earthquakes observed at 179 seismic stations the amplitude anomalies are considered to depend on four factors intrinsic attenuation along the ray path elastic focusing effects along the ray path a source factor accounting for uncertainties in the strength of excitation and a receiver factor accounting for uncertainties in the response at the station the amplitude data are inverted simultaneously for global maps of attenuation expanded in spherical harmonics up to degree 12 global maps of phase velocity expanded to degree 20 and source and receiver correction factors all four variable types are shown to be important in explaining the amplitude anomalies a data set of phase delay measurements provides additional constraints on velocity structure the maps of attenuation obtained by simultaneous inversion for elastic and anelastic models contain important features that are not robustly imaged when the effect of focusing on wave amplitude is ignored these include high attenuation along western north america and along the east pacific rise and other ridge systems and low attenuation associated with stable continental interiors the global attenuation maps exhibit a strong correlation with phase velocity maps corrected for the effect of the crust particularly for periods 200 s the correlation suggests that the variability in both q and velocity in the shallow upper mantle is primarily thermal in origin

origin of a mesozoic granite with a type characteristics from the north china craton highly fractionated from i type magmas we report geochronological geochemical and isotopic data for the mesozoic shangshuiquan granite from the northern margin of the north china craton the granite is highly fractionated with sio2 74 occurrence of annitic biotite high contents of alkalis k2o na2o rb y nb and heavy rare earth elements high feot mgo low contents of cao al2o3 ba and sr and large negative eu anomalies makes it indistinguishable from typical a type granites a mantle derived origin for the rocks of the granite is not favored because their high initial 87sr 86sr 0 706 and low end t 15 are completely different from either those of the lithospheric or asthenospheric mantle in fact their sr nd isotopes fall within the range of sr nd isotopic compositions of the archean granulite terrains and are comparable to those of mesozoic crustal derived i type granitoids in the region therefore the shangshuiquan granite is considered to be dominantly derived from partial melting of the ancient lower crust its parental magmas prove to be similar to i type magmas and to have undergone extensive fractionation during its ascent this is supported by the fact that some of the nearby hannuoba feldspar rich granulite xenoliths can be indeed regarded as the early cumulates in terms of their mineralogy chemistry sr nd isotopes and zircon u pb ages and hf isotopes it is furthermore argued that some of highly fractionated granites worldwide especially those with a type characteristics and lacking close relationship with unfractionated rocks may in fact be fractionated i type granites this suggestion can explain their close temporal and spatial associations as well as similar sr nd isotopes with i type granites our study also sheds new light on the petrogenesis of deep crustal xenoliths

distribution and petrogenetic behaviour of trace elements in granitic pegmatite quartz from south norway the present study documents that the trace element distribution in granitic quartz is highly sensitive to cafc processes in granitic melts igneous quartz efficiently records both the origin and the evolution of the granitic pegmatites aluminium p li ti ge and na in that order of abundance comprises 95 of the trace elements most samples feature 1 ppm of any of these elements the remnant 5 includes k fe be b ba and sr whereas the other elements are present at concentrations lower than the detection limit potassium fe be and ti are relatively compatible hence obtain the highest concentrations in early formed quartz phosphorous ge li and al are relatively incompatible and generally obtain the highest concentrations in quartz that formed at lower temperatures from more evolved granitic melts the ge ti the ge be the p ge and the p be ratios of quartz are strongly sensitive to the origin and evolution of the granitic melts and similarly the rb sr and the rb k ratios of k feldspars may be utilised in petrogenetic interpretations however the quartz trace element ratios are better at distinguishing similarities and differences in the origin and evolution of granitic melts after evaluating the different trace element ratios the ge ti ratio appears to be most robust during subsolidus processes in the igneous systems hence probably should be the preferred ratio for analysing and understanding petrogenetic processes in granitic igneous rocks

attenuation tomography of the upper mantle we present qsadr17 a global shear wave attenuation model of the upper mantle synthetic tests confirm that large scale shear attenuation anomalies are resolved in the whole upper mantle with limited vertical smearing 50 km qsadr17 shows strong correlation with surface tectonics down to 200 km depth with low attenuation beneath continents and high attenuation beneath oceans the attenuation signal near 250 km depth is dominated by a high quality factor along subduction zones attenuating anomalies are found beneath mid ocean ridges down to 150 km and under most pacific hotspots from the lithosphere down to the transition zone the presence of broad attenuating anomalies at 150 km depth in the pacific ocean suggests that several thermal plumes pond in the asthenosphere evidence for compositional heterogeneities is found in the lithosphere at the base of cratons and in a number of active regions

local site effects on weak and strong ground motion abstract this is a review of the current state of the art in characterizing effects of local geology on ground motion a new horizon is clear in this aspect of strong motion studies non linear amplification at sediment sites appears to be more pervasive than seismologists used to think several recent observations about the weak motion and the strong motion suggest that the non linear amplification at sediment sites may be very common first on average the amplification is always greater at the younger sediment sites for all frequencies up to 12 hz in the case of weak motion while the relation is reversed for frequencies higher than 5 hz in the case of strong motion secondly the application of the amplification factor determined from weak motion overestimates significantly the strong motion at sediment sites observed during the loma prieta earthquake within the epicentral distance of about 50 km thirdly the variance of peak ground acceleration around the mean curve decreases with the increasing earthquake magnitude finally the above non linear effects are expected from geotechnical studies both in the magnitude of departure from the linear prediction and in the threshold acceleration level beyond which the non linearity begins

origin of ti rich rims in quartz phenocrysts from the upper bandelier tuff and the tunnel spring tuff southwestern usa four compositionally zoned melt inclusion bearing quartz phenocrysts from the upper bandelier tuff new mexico and the tunnel spring tuff utah were examined in detail by cathodoluminescence laser ablation icp ms and titanium in quartz titaniq thermobarometry in order to reconstruct the conditions of quartz crystallization temperature and tio2 activity atio2 in the magma were estimated from melt inclusion compositions by means of zircon saturation thermometry and an experimentally calibrated tio2 solubility model whereas pressure was estimated with the most recent calibration of the titaniq thermobarometer on the host quartz next to the analyzed melt inclusions all four investigated quartz phenocrysts display a low luminescent ti poor core overgrown by a high luminescent ti rich rim reconstructed p t atio2 conditions suggest that the rimward increase in the ti content of the two quartz crystals from the upper bandelier tuff is due to a combination of increasing temperature increasing atio2 and decreasing pressure with the temperature effect being dominant in one crystal and the atio2 effect being dominant in the other crystal in the two crystals from the tunnel spring tuff the rimward increase in ti content is mostly due to increasing temperature but in one of them a negative pressure change played an equally important role this study demonstrates that in rapidly cooled peraluminous or metaluminous rhyolites the crystallization conditions of quartz phenocrysts can be reconstructed at the scale of individual growth zones which allows to investigate the origin and evolution of such magmas in great detail

q tomography of the upper mantle using three component long period waveforms summary we present a degree 8 3 d q model qrlw8 of the upper mantle derived from three component surface waveform data in the period range 60 400 s the inversion procedure involves two steps in the first step 3 d whole mantle velocity models are derived separately for elastic sh transverse component and sv vertical and longitudinal component velocity models using both surface and body waveforms and the non linear asymptotic coupling theory nact approach in the second step the surface waveforms thus aligned in phase are inverted to obtain a 3 d q model in the depth range 80 670 km various stability tests are performed to assess the quality of the resulting q model and in particular to assess possible contamination from focusing effects we find that the 3 d patterns obtained are stable but the amplitude of the lateral variations in q is not well constrained because large damping is necessary to extract the weak q signal from data the model obtained agrees with previous results in that a strong correlation of q with tectonics is observed in the first 250 km of the upper mantle with high attenuation under oceanic regions and low attenuation under continental shields it is gradually replaced by a simpler pattern at larger depth at the depths below 400 km the q distribution is generally dominated by two strong minima one under the southern pacific and one under africa yielding a strong degree 2 pattern most hotspots are located above regions of low q at this depth ridges are shallow features in both velocity and q models

short period surface wave phase velocities across the conterminous united states abstract surface wave phase velocity maps for the full footprint of the usarray transportable array ta across the conterminous united states are developed and tested three component long period continuous seismograms recorded on more than 1800 seismometers most of which were deployed for 18 months or longer are processed using a noise cross correlation technique to derive inter station love and rayleigh dispersion curves at periods between 5 and 40 s the phase velocity measurements are quality controlled using an automated algorithm and then used in inversions for love and rayleigh phase velocity models at discrete periods on a 0 25 by 0 25 pixel grid the robustness of the results is examined using comparisons of maps derived from subsets of the data a winter summer division of the cross correlation data results in small model differences indicating relatively minor sensitivity of the results to seasonal variations in the distribution of noise sources division of the dispersion data based on inter station azimuth does not result in geographically coherent model differences suggesting that azimuthal anisotropy at the regional scale is weak compared with variations in isotropic velocities and does not substantially influence the results for isotropic velocities the phase velocity maps and dispersion measurements are documented and made available as data products of the 10 year long usarray ta deployment

cathodoluminescence imaging and titanium thermometry in metamorphic quartz cathodoluminescence cl of quartz from metamorphic rocks representing a range of conditions from the garnet grade to the migmatite grade reveals a variety of textures that is a function of metamorphic grade and deformation history ti concentrations determined by electron microprobe and ion microprobe generally correlate with cl intensity blue wavelengths and application of the ti in quartz thermometer titaniq reflects the temperature of quartz growth or recrystallization and in some settings modification by diffusion quartz from garnet grade samples is not visibly zoned records temperatures of 425 475 c and is interpreted to have recrystallized during fabric formation quartz grains from staurolite grade samples are zoned in cl with markedly darker cores and brighter rims some of which are interpreted to have been produced by the dominant staurolite producing reaction whereas others are interpreted as having formed by diffusion of ti into quartz rims quartz from the matrix of kyanite and sillimanite grade samples are generally unzoned although locally displays slightly brighter rims higher ti quartz inclusions within garnet and staurolite have distinctly brighter rims which are interpreted as having been produced by diffusive exchange with the host mineral quartz from migmatite grade samples displays highly variable cl intensity which is dependent on the location of the grain matrix grains in melanosomes are largely unzoned or rarely zoned with darker cores leucosome quartz is strongly zoned with bright cores and dark rims and is interpreted as having formed during crystallization of the melt locally within the leucosome is observed oscillatory zoned quartz which is interpreted as a subsolidus recrystallization to achieve strain relaxation quartz inclusions within garnet or plagioclase crystals often show bright domains separated by zones of dark cl these enigmatic textures possibly reflect local melting fluxed by fluid inclusions temperatures calculated from the ti in quartz thermometer are a function of the metamorphic grade of the sample the textural setting of the quartz the reaction history and the deformation history of the rock the titaniq temperatures can be used to constrain the conditions at which various metamorphic processes have occurred

combining csd and isotopic microanalysis magma supply and mixing processes at stromboli volcano aeolian islands italy integrating isotopic microanalysis with other analytical techniques creates powerful new methodologies for understanding the evolution of rock samples at the sub grain scale here we present crystal size distribution csd data for a 26 000 year old sample from stromboli volcano and accompanying isotopic microanalysis of the phenocrysts a technique called the icsd plot is introduced which given stated assumptions allows the integration of both sets of data to generate timelines of isotopic evolution through the volcanic system the combined approach is powerful allowing investigation of the magma supply mixing crystallisation and contamination processes prior to eruption of a volcanic sample for stromboli volcano the combined analysis suggests that the change in magma type following a cone collapse took roughly five years to complete similar to the timescale of changes seen in recent decades

textural and chemical evolution of a fractionated granitic system the podlesi stock czech republic the podlesigranite stock czech republic is a fractionated peraluminous f li and p rich and sn w nb ta bearing rare metal granite system its magmatic evolution involved processes typical of intrusions related to porphyry type deposits explosive breccia comb layers rare metal granites stockscheider and rare metal pegmatites extreme f p li enrichment nb ta sn minerals layering geological textural and mineralogical data suggest that the podlesigranites evolved from fractionated granitic melt progressively enriched in h2o f p li etc quartz k feldspar fe li mica and topaz bear evidence of multistage crystallization that alternated with episodes of resorption changes in chemical composition between individual crystal zones and or populations provide evidence of chemical evolution of the melt variations in rock textures mirror changes in the pressure and temperature conditions of crystallization equilibrium crystallization was interrupted several times by opening of the system and the consequent adiabatic decrease of pressure and temperature resulted in episodes of nonequilibrium crystallization the podlesigranites demonstrate that adiabatic fluctuation of pressure bswinging eutecticq and boundary layer crystallization of undercooled melt can explain magmatic layering and unidirectional solidification textures usts in highly fractionated granites d 2004 elsevier b v all rights reserved

role of the gulf stream and kuroshio oyashio systems in large scale atmosphere ocean interaction a review abstract ocean atmosphere interaction over the northern hemisphere western boundary current wbc regions i e the gulf stream kuroshio oyashio and their extensions is reviewed with an emphasis on their role in basin scale climate variability sst anomalies exhibit considerable variance on interannual to decadal time scales in these regions low frequency sst variability is primarily driven by basin scale wind stress curl variability via the oceanic rossby wave adjustment of the gyre scale circulation that modulates the latitude and strength of the wbc related oceanic fronts rectification of the variability by mesoscale eddies reemergence of the anomalies from the preceding winter and tropical remote forcing also play important roles in driving and maintaining the low frequency variability in these regions in the gulf stream region interaction with the deep western boundary current also likely influences the low frequency variability surface heat fluxes damp the low frequency sst anomalies ove

amplification and attenuation across usarray using ambient noise wavefront tracking as seismic traveltime tomography continues to be refined using data from the vast usarray data set it is advantageous to also exploit the amplitude information carried by seismic waves we use ambient noise cross correlation to make observations of surface wave amplification and attenuation at shorter periods 8 32 s than can be observed with only traditional teleseismic earthquake sources we show that the wavefront tracking approach can be successfully applied to ambient noise correlations yielding results quite similar to those from earthquake observations at periods of overlap this consistency indicates that the wavefront tracking approach is viable for use with ambient noise correlations despite concerns of the inhomogeneous and unknown distribution of noise sources the resulting amplification and attenuation maps correlate well with known tectonic and crustal structure at the shortest periods our amplification and attenuation maps correlate well with surface geology and known sedimentary basins while our longest period amplitudes are controlled by crustal thickness and begin to probe upper mantle materials these amplification and attenuation observations are sensitive to crustal materials in different ways than traveltime observations and may be used to better constrain temperature or density variations we also value them as an independent means of describing the lateral variability of observed rayleigh wave amplitudes without the need for 3 d tomographic inversions

seismic attenuation in the eastern australian and antarctic plates from multiple scs waves the attenuation of seismic shear waves in the mantle beneath the eastern australian and antarctic plates is analyzed using a large data set of multiple scsn waves reflected n times at the core mantle boundary and n 1 times at the surface the data are the transverse components of deep earthquakes from the subduction zones north and east of australia recorded at stations in antarctica australia indonesia new caledonia and new zealand the data are filtered with narrow band pass filters at 5 frequencies in the range 0 013 0 040 hz the scsn 1 scsn amplitude ratios of successive scs phases are compared to the ratios computed for synthetic seismograms for the same paths and same focal mechanisms in order to eliminate the effects of source radiation and geometric attenuation the synthetic seismograms are computed from a summation of toroidal modes for the 1 d reference model prem dziewonski anderson 1981 the observed to computed spectral ratios appear consistent for similar paths they reveal that the attenuation is not frequency dependent that the contribution of scattering to attenuation is low and that the prem model is a valuable reference model for the study region at the considered frequencies an inversion of the data at 0 026 hz is performed to retrieve the quality factor q in the upper mantle in regions defined using a priori constraints inferred from seismic shear velocities q values close to those of prem are found beneath the australian and antarctic cratons lower values beneath the eastern australian phanerozoic margin and very low values beneath the oceanic region between australia and antarctica where ridges and a triple junction are present the australian antarctic discordance along the south indian ridge appears as an exception with a q value close to those of stable continents the highest q values are found beneath the subduction zones a feature which is not apparent in global attenuation models possibly because of its narrow lateral extension and because it extends at depths larger than those sampled by surface waves despite limitations due to the uneven distribution of the scsn bounce points at the surface and to the difficulty of collecting a large number of high quality data our approach appears very promising it is complementary to the more widely used determination of seismic attenuation using surface waves because it provides increased depth coverage and a broader spectral coverage it therefore has a considerable potential in future investigations of mantle structure and dynamics

trace element evolution of quartz in the charnockitic kleivan granite sw norway the ge ti ratio of quartz as an index of igneous differentiation article i nfo trace element analyses of quartz from the layered charnockitic kleivan granite in the rogaland igneous province rogaland municipality sw norway reveal that the trace element composition of quartz can track igneous evolution during differentiation of the magma combined sem cl imaging and la icp ms analyses allow identification and analysis of primary igneous quartz al ti li and ge are the most abundant trace elements in the kleivan quartz and each element shows a characteristic evolution during differentiation of the granitic magma the ge ti ratio of quartz is a reliable index of the magmatic evolution of granitic igneous systems since ti and ge show pronounced compatible and incompatible characteristics respectively the temperature of the quartz crystallisation varies from 850 c during charnockite formation to 645 c in the most evolved aplitic granite and granitic pegmatite therefore the regular evolution of ti and ge in quartz during cooling of the melt may be used as an igneous geothermometer the li evolution pattern of quartz is mostly controlled by the li content of the melt hence by the absence or presence of li bearing phases forming during solidification of the melt al in quartz is controlled by the aluminium saturation index of the melt accordingly al in quartz is constant during crystallisation of a metaluminous magma and increases during peraluminous conditions the study of rock mineralogy and whole rock geochemistry are not the only methods that can be used to assess the petrogenesis of silica oversaturated rocks the purpose of this study is to demonstrate that the trace element chemistryof quartz and inparticular the ge ti ratio can be used as a petrogenetic tool to characterise an evolving igneous system and can provide information that otherwise may be difficult to obtain quartz is a good mineral for recording and storing the differentiation processes in granitic systems compared to other

global lateral variations of shear wave attenuation in the upper mantle we analyze several thousand high quality globally recorded ss s differential waveforms to constrain the lateral variation of shear wave attenuation q in the upper mantle we use a multitaper frequency domain technique to measure attenuation parameterized by a t operator and implement a robust estimation technique to compute t and its variance the differential waveform technique minimizes the effect of factors such as finite source duration and structural complexity near the source and receiver so the differential ss s waveforms are mainly sensitive to the shear attenuation in the upper mantle under the ss bounce point we use seismograms recorded at ranges of 45 to 100 and compute the ss s differential t from the broadening of the ss waveform relative to the hilbert transform of the s waveform a careful choice of fitting windows allows us to reduce the biasing effects of interfering phases which can affect t by up to 0 5 s the t residuals with respect to preliminary reference earth model prem vary by 1 5 s with an average of 0 24 s our study suggests an average q value of 112 most of the lateral variations of q are within 30 of this value in the top 400 km of the mantle slightly lower than the prem value of 128 there is a qualitative correlation of t residual with tectonic region with distinctly higher attenuation observed under young oceans compared to platforms and shields also the lateral variations of the residuals are similar in trend to those observed in studies of the attenuation of scs multiples at long wavelengths the qp map shows a modest correlation with shear wave attenuation maps computed from surface wave analyses and with the patterns of lateral variations of shear velocities at certain upper mantle depths predicted by the model s16b30 the correlation with the velocity model is highest at 300 500 km depth indicating that there may be a contribution to long wavelength attenuation from relatively deep regions formal inversion for an upper mantle q model shows that while lateral resolution is quite good depth resolution is poor as might be expected better depth resolution must await combined body wave and surface wave inversions

western boundary currents and frontal air sea interaction gulf stream and kuroshio extension abstract in the northern hemisphere midlatitude western boundary current wbc systems there is a complex interaction between dynamics and thermodynamics and between atmosphere and ocean their potential contribution to the climate system motivated major parallel field programs in both the north pacific kuroshio extension system study kess and the north atlantic climate variability and predictability clivar mode water dynamics experiment climode and preliminary observations and analyses from these programs highlight that complexity the gulf stream gs in the north atlantic and the kuroshio extension ke in the north pacific have broad similarities as subtropical gyre wbcs but they also have significant differences which affect the regional air sea exchange processes and their larger scale interactions the 15 yr satellite altimeter data record which provides a rich source of information is combined here with the longer historical record from in situ data to describe and compare the curr

titaniq a titanium in quartz geothermometer titanium is one of many trace elements to substitute for silicon in the mineral quartz here we describe the temperature dependence of that substitution in the form of a new geothermometer to calibrate the titaniq thermometer we synthesized quartz in the presence of rutile and either aqueous fluid or hydrous silicate melt at temperatures ranging from 600 to 1 000 c at 1 0 gpa the ti contents of quartz in ppm by weight from 13 experiments increase exponentially with reciprocal t as described by text log left x text qtz text ti right 5 69 pm 0 02 frac 3765 pm 24 t k application of this thermometer is straightforward typically requiring analysis of only one phase quartz this can be accomplished either by epma for crystallization temperatures above 600 c or by sims for temperatures down to at least 400 resulting temperature estimates are very precise usually better than 5 c potentially allowing detailed characterization of thermal histories within individual quartz grains although calibrated for quartz crystallized in the presence of rutile the thermometer can also be applied to rutile absent systems if tio2 activity is constrained

development of microcracks in granites during cooling and uplift examples from the variscan basement in ne bavaria germany abstract microcracks in two late variscan granites in ne bavaria provide information about regional paleostress directions and p t conditions during cooling and uplift in both granites three prominent generations of healed microcracks called ci cii ciii constitute an orthorhombic fabric the orientation of which is closely related to the mesoscopic joint pattern we present a model relating this orthorhombic crack fabric not only to external deviatoric stresses but also to internal stresses on the grain scale resulting from the strong thermal contraction of quartz relative to the feldspar framework at the deepest level 1 subvertical steep ci cracks developed normal to 3 and selectively in the quartz their formation caused a stress uncoupling of quartz aggregates from the external 3 direction so that further contraction of quartz produced steep cii cracks normal to 2 forming bridges between ci cracks at higher levels 2 subvertical the same process reactivated the ci cracks and now formed horizontal crack bridges ciii p t estimates based on fluid inclusion data and inferred geothermal gradients are 250 400 c at 1 5 3 kbar for ci cii cracks and 150 200 c at 1 2 kbar for ciii cracks the orientation of the younger open cracks which formed at higher crustal levels partly corresponds to the present regional stress field

application of cathodoluminescence to magmatic quartz in a tin granite case study from the schellerhau granite complex eastern erzgebirge germany a model of the cooling history of tin bearing granitic magma forming the schellerhau granites eastern erzgebirge germany is shown on the basis of quartz textures similar grain size similar grain habit and correlatable growth textures of phenocrysts in different granite varieties give proof of a common crystallization history before the melts of the schellerhau granite varieties were intruded four nucleation events occurred during crystallization in different crustal levels between about 20 and 1 km depth the parental melt of the schellerhau granites is interpreted to have contained 2 5 wt h2o originally the water content of the melt during the subvolcanic intrusion stage amounted to more than 5 wt and characterizes highly evolved residual melts that enable the formation of tin deposits this study contributes to a better understanding of the development and behaviour of fractionated tin bearing granitic melts and links quartz cathodoluminescence cl with microanalytical studies

strong eddy compensation for the gulf stream heat transport using a high resolution ocean model forced with high resolution atmospheric fields a 5 year mean heat budget of the upper ocean in the gulf stream gs region is analyzed the heat brought to the region with the mean flows along the gs path is 2 3 times larger than the heat loss to the atmosphere with the difference being balanced by a strong cooling effect due to lateral eddy heat fluxes however over a broad area off the grand banks the eddies warm the uppermost ocean layers partly compensating for the loss of heat to the atmosphere the upward eddy heat flux which brings heat from the deeper ocean to the upper layers is 30 80 of the surface heat loss

a global tomographic model of shear attenuation in the upper mantle we present a global three dimensional model of shear attenuation in the upper mantle based on the measurement of amplitudes of low frequency 100 300s rayleigh waves observed at stations of the geoscope and iris networks attenuation coefficients are measured on r1 and r2 paths using a method which minimizes the effects of focussing due to propagation in a three dimensional elastic earth through a series of tests which in particular involve the computation of synthetic models of attenuation and focussing we demonstrate that long wavelength lateral variations in attenuation in the first 400 500 km of the mantle can indeed be resolved the model is obtained in a two step procedure the first step consists in the computation of maps of rayleigh wave attenuation at different periods using an inversion method without a priori parametrisation which involves the introduction of a correlation length chosen here at 3000 km to optimize the trade off between resolution and variance in the model in the second step after corrections for shallow structure an inversion with depth is performed assuming lateral heterogeneity is confined to depths between 80 and 650 km the resulting model presents lateral variations in qp that are correlated with tectonic features in particular ridges and shields in the first 250 km of the upper mantle below that depth the pattern shifts and becomes correlated with the hotspot distribution particularly so if the buoyancy strength of hotspots is taken into account two major low velocity zones appear to be located in the central pacific and beneath northern africa in the depth range 300 500 km this pattern seems to continue at greater depth but resolution becomes insufficient below 500 km to draw definitive conclusions the smooth lateral variations retrieved are on the order of 50 down to 400 km we propose an interpretation in terms of plume lithosphere ridge interaction in the upper mantle arguing for deflection of the bulk of hot upwelling material from plumes towards ridges which may be occurring between 200 and 300 km depth

genesis of the wurinitu w mo deposit inner mongolia northeast china constraints from geology fluid inclusions and isotope systematics abstract the wurinitu w mo deposit is located in the erlian east ujimqin metallogenic belt in the great xing an range ne china tungsten and molybdenum mineralization generally occurs as veins in quartz hosted by the middle to lower ordovician wall rocks or as disseminations in the early cretaceous monzogranite intrusions fluid inclusion studies and multiple isotope analyses provide systematic evidence to determine the evolution of the hydrothermal fluids the source of metals and fluids as well as mineral precipitation mechanisms which are significant for the magmatic hydrothermal system but are poorly understood three types of fluid inclusion assemblages fias including l liquid rich two phase fias v vapor rich two phase fias and l v liquid vapor two phase fias have been identified in quartz veins from the w mineralization i mo mineralization ii and quartz carbonate iii stages at wurinitu the ore forming fluids evolved from a high to moderate temperature and moderate to low salinity h2o nacl co2 system in the w and mo mineralization stages to a low temperature and low salinity h2o nacl system in the quartz carbonate stage they were trapped at temperatures of 365 c 266 c and 198 c the results of hydrogen and oxygen isotope analyses 18oh2o 4 0 to 7 7 dh2o 116 to 92 indicate that the stage i fluids dominantly originated from magmatic water and the stages ii and iii show addition of meteoric water sulfur 34svcdt 1 9 4 0 and lead isotope values 206pb 204pb 18 099 18 728 207pb 204pb 15 527 15 616 and 208pb 204pb 38 019 38 465 suggest that the ore metals in the hydrothermal fluids were derived from the granitic magma all these observations reveal that 1 the wurinitu w mo deposit is a magmatic hydrothermal ore system 2 w and mo mineralization occurred under lithostatic pressure of 203 294 bars and hydrostatic pressure of 102 bars respectively and 3 fluid boiling and mixing with meteoric water might be the key factors controlling the large scale ore deposition at wurinitu

a site conditions map for california based on geology and shear wave velocity one simple way of accounting for site conditions in calculating seismic hazards is to use the shear wave velocity in the shallow subsurface to classify materials the average shear wave velocity to 30 m v 30s has been used to develop site categories that can be used for modifying a calculated ground motion to account for site conditions we have prepared a site category map of california by first classifying the geologic units shown on 1 250 000 scale geologic maps our classification of geologic units is based on v 30s measured in 556 profiles and geological similarities between units for which we have v s data and the vast majority of units for which we have no data we then digitized the geologic boundaries from those maps that separated units with different site classifications v s data for california shows that several widespread geologic units have ranges of v 30s values that cross the boundaries between nehrp ubc site categories the franciscan complex has v 30s values across ubc categories b and c with a mean value near the boundary between those two categories older alluvium and late tertiary bedrock have v 30s values that range from about 300 to about 450 m sec across the boundary between categories c and d to accommodate these units we have created intermediate categories which we informally call bc and cd geologic units that have or are interpreted to have v 30s values near the boundary of the ubc categories are placed in these intermediate units in testing our map against the available v 30s measurements we have found that 74 of the measured v 30s values fall within the range assigned to the v s category where they fall on the map this ratio is quite good considering the inherent problems in plotting site specific data on a regional map and the variability of physical properties in geologic units we have also calculated the mean and distribution of v 30s for each of our map units and prepared composite profiles showing the variation of v s in the upper 100 m from the available v s data these data show that the map categories that we have defined based on geologic units have different v s properties that can be taken into account in calculating seismic hazards

mapping the upper mantle three dimensional modeling of earth structure by inversion of seismic waveforms a method is presented for the inversion of waveform data for the three dimensional distribution of seismic wave velocities the method is applied to data from the global digital networks international deployment of accelerometers global digital seismograph network the selected data set consists of some 2000 seismograms corresponding to 53 events and 870 paths the moment tensors of the earthquakes are determined through an iterative procedure which minimizes the corrupting influence of lateral heterogeneity a global model is constructed for shear wave velocity expanded up to degree and order 8 in spherical harmonics and described by a cubic polynomial in depth for the upper 670 km of the earth s mantle although no a priori information is incorporated the model predictions reproduce much of what is known about the dispersion of mantle waves for example high phase velocities for shields low velocities at ridges and a strong degree 2 pattern for rayleigh waves since the method makes use of complete waveforms overtone data are also included it is shown that the model is reproducible in that substantially the same model can be constructed from each half of the total data set considered independently the model shows that shields and ridges are major features in the depth interval 25 250 km the ridges of the southern pacific and the larger shields persist to 350 km but the southeast indian rise is underlain by a high velocity anomaly at this depth as is much of the mid atlantic ridge at 450 650 km the major features are a broad region of high velocities incorporating south america much of the south atlantic and parts of west africa a broad region of low velocities in the central and eastern pacific high velocities in the western pacific and a low velocity anomaly beneath the red sea and the gulf of aden in the absence of a crustal correction degrees 2 and 3 show a high positive correlation with the geoid paradoxically this is largely destroyed when the distribution in crustal thickness is taken into account spherical harmonic degrees 4 7 show a significant negative correlation

genesis of the zhangquanzhuang gold deposit in the northern margin of north china craton constraints from deposit geology and ore isotope geochemistry abstract the genesis of orogenic gold deposits in the northern margin of the north china craton ncc is still ambiguous and this is addressed in this case study on the zhangquanzhuang gold deposit this deposit shows features typical of orogenic gold deposits including quartz vein type mineralization controlled by shear zones sericite quartz pyrite carbonate alteration along shear zones absence of connection to any magmatic intrusion and occurrence of native gold and electrum the zhangquanzhuang gold deposit which is hosted in archean high grade metamorphic rocks was formed in mesozoic and largely later than the regional metamorphism in this deposit the pb isotope compositions of sulfides in ores have low 206pb 204pb ratios of 16 874 17 007 207pb 204pb ratios of 15 368 15 410 and 208pb 204pb ratios of 37 023 37 215 and these are much less radiogenic than those of regional metamorphic and magmatic rocks this finding precludes the possible derivation of ore fluid from regional magmatism and metamorphism in pyrite hosted fluid inclusions in the ores the 3he 4he and 40ar 36ar ratios are 1 26 1 75 ra and 1622 2816 respectively showing prominent signature of mantle sources these geochemical features together with the large temporal discrepancy between regional metamorphism and mineralization suggest that ore fluid and metal had a subcrustal source similar to the gold deposits in the jiaodong gold province in the southeastern margin of the ncc the calculated 34sh2s values for the ore fluid are 2 31 4 48 which are heavier than the 34s of depleted mantle the 18o of ore related quartz mostly cluster around 11 implying high 18o of subcrust derived ore fluid the stable o and s isotope data indicate that the subcrustal source has been metasomatized by subducted crustal sediments

trace elements in hydrothermal quartz relationships to cathodoluminescent textures and insights into vein formation high resolution electron microprobe maps show the distribution of ti al ca k and fe among quartz growth zones revealed by scanning electron microscope cathodoluminescence sem cl from 12 hydrothermal ore deposits formed between 100 and 750 c the maps clearly show the relationships between trace elements and cl intensity in quartz among all samples no single trace element consistently correlates with variations in cl intensity however in vein quartz from five porphyry cu mo au deposits cl intensity always correlates positively with ti concentrations suggesting that ti is a cl activator in quartz formed at 400 c ti concentrations in most rutile bearing vein quartz from porphyry copper deposits indicate reasonable formation temperatures of 750 c using the titaniq geothermometer titanium concentrations of 10 ppm in all veins that formed at temperatures 350 c suggest a broad correlation between ti concentrations and temperature of quartz precipitation in quartz from most deposits formed at 2000 ppm but in high temperature quartz al concentrations are consistently in the range of several hundred ppm aluminum concentrations in quartz reflect the al solubility in hydrothermal fluids which is strongly dependent on ph aluminum concentrations in quartz therefore reflect fluctuations in ph that may drive metal sulfide precipitation in hydrothermal systems

implications of grain size evolution on the seismic structure of the oceanic upper mantle abstract we construct a 1 d steady state channel flow model for grain size evolution in the oceanic upper mantle using a composite diffusion dislocation creep rheology grain size evolution is calculated assuming that grain size is controlled by a competition between dynamic recrystallization and grain growth applying this grain size evolution model to the oceanic upper mantle we calculate grain size as a function of depth seafloor age and mantle water content the resulting grain size structure is used to predict shear wave velocity v s and seismic quality factor q for a plate age of 60 myr and an olivine water content of 1000 h 10 6 si we find that grain size reaches a minimum of 15 mm at 150 km depth and then increases to 20 30 mm at a depth of 400 km this grain size structure produces a good fit to the low seismic shear wave velocity zone lvz in oceanic upper mantle observed by surface wave studies assuming that the influence of hydrogen on anelastic behavior is similar to that observed for steady state creep further it predicts a viscosity of 10 19 pa s at 150 km depth and dislocation creep to be the dominant deformation mechanism throughout the oceanic upper mantle consistent with geophysical observations we predict larger grain sizes than proposed in recent studies in which the lvz was explained by a dry mantle and a minimum grain size of 1 mm however we show that for a 1 mm grain size diffusion creep is the dominant deformation mechanism above 100 200 km depth inconsistent with abundant observations of seismic anisotropy from surface wave studies we therefore conclude that a combination of grain size evolution and a hydrated upper mantle is the most likely explanation for both the isotropic and anisotropic seismic structure of the oceanic upper mantle our results also suggest that melt extraction from the mantle will be significantly more efficient than predicted in previous modeling studies that assumed grain sizes of 1 mm

eddy mean flow interaction in the gulf stream at 68 w part i eddy energetics abstract from june 1988 to august 1990 twelve tall high performance current meter moorings measured the gulf stream s velocity and temperature fields at nominal depths of 400 m 700 m 1000 m and 3500 m along three lines centered at 68 w the overall eddy variability during the 26 month experiment was dominated by six large amplitude trough formation events with each event lasting approximately one month to determine the source s of energy for this eddy variability the eddy energy budget is evaluated traditionally the baroclinic conversion of mean potential energy to eddy potential energy is defined as a downgradient heat flux however because a nondivergent heat flux can be downgradient even under conditions in which there is no barolinic conversion occurring a better more dynamically correct definition of a baroclinic conversion rate is a downgradient horizontally divergent heat flux the horizontally divergent heat flux component is estimated to be approximately half the full horizontal hea

textural features and chemical evolution in ta nb oxides implications for deuteric rare metal mineralization in the yichun granite marginal pegmatite southeastern china

3 d upper mantle shear velocity and attenuation from fundamental mode free oscillation data summary we present the results of global measurements of spheroidal and toroidal fundamental mode eigenfrequencies as well as fundamental spheroidal mode attenuation made from a data set consisting primarily of records from the geoscope network data processing includes variable filtering and account is taken of higher order effects along the dispersion branch local frequency and attenuation maps are first obtained as a function of angular order by a regionalization scheme based on the introduction of a correlation length in a second step after correction for shallow layer effects shear velocity maps at different depths in the mantle are obtained by simultaneous inversion of spheroidal and toroidal local frequency maps the results confirm the correlation of shear velocity with large scale tectonic features in the first 200 km of the mantle below that depth the maps are dominated by a degree 2 pattern whose power is peaked around a depth of 300 km shallower than inferred in the first 3 d global studies of the upper mantle and correlated with a degree 2 in attenuation thus confirming the results of our earlier study of degree 2 in the upper mantle we also report estimates of spherically averaged eigenfrequencies for fundamental spheroidal and toroidal mode branches

crystal size distribution csd in rocks and the kinetics and dynamics of crystallization ii makaopuhi lava lake crystal size distribution csd theory has been applied to drill core samples from makaopuhi lava lake kilauea volcano hawaii plagioclase and fe ti oxide size distribution spectra were measured and population densities n were calculated and analyzed using a steady state crystal population balance equation n n0 exp l g slopes on ln n versus crystal size l plots determine the parameter g a product of average crystal growth rate g and average crystal growth time the intercept is j g where j is nucleation rate known temperature depth distributions for the lava lake provide an estimate of effective growth time allowing nucleation and growth rates to be determined that are independent of any kinetic model plagioclase growth rates decrease with increasing crystallinity 9 9 5 4 10 11 cm s as do plagioclase nucleation rates 33 9 1 6 10 3 cm3 s ilmenite growth and nucleation rates also decrease with increasing crystallinity 4 9 3 4 10 10 cm s and 15 2 2 10 3 cm3 s respectively magnetite growth and nucleation rates are also estimated from the one sample collected below the magnetite liquidus g 2 9 10 10 cm s j 7 6 10 2 cm3 s moments of the population density function were used to examine the change in crystallization rates with time preliminary results suggest that total crystal volume increases approximately linearly with time after 50 crystallization a more complete set of samples is needed for material with 50 crystals to define the entire crystallization history comparisons of calculated crystallization rates with experimental data suggests that crystallization in the lava lake occurred at very small values of undercooling this interpretation is consistent with proposed thermal models of magmatic cooling where heat loss is balanced by latent heat production to maintain equilibrium cooling

ore genesis and hydrothermal evolution of the donggebi porphyry mo deposit xinjiang northwest china evidence from isotopes c h o s pb fluid inclusions and molybdenite re os dating

formation and evolution of snowball quartz phenocrysts in the dongping porphyritic granite hebei province china insights from fluid inclusions cathodoluminescence trace elements and crystal size distribution study abstract quartz phenocrysts are common in many granites volcanic rocks metamorphic rocks and hydrothermal deposits the dongping porphyritic granite contains large amounts of rounded to sub rounded quartz phenocrysts minerals in this porphyritic granite show weak but distinct orientation dense clusters of fluid inclusions and albite crystals exist in the quartz showing snowball texture two types of snowball quartz are recognized 1 large snowball quartz phenocrysts containing large albite grains distributed in the core and small albite grains distributed in the mantle and 2 small snowball quartz crystals containing small albite grains the granite is characterized by high sio2 7 15 73 44 wt k2o 4 70 5 10 wt and na2o 4 93 5 21 wt contents low cao 0 41 0 71 wt mgo 0 03 0 05 wt fe2o3 0 87 0 94 wt tio2 0 02 0 03 wt and ree 7 10 9 80 ppm contents the granite has similar mineral and chemical composition with the aplite in the area and they were derived from the residual melt of the shuiquangou magma that suffered assimilation fractional crystallization process fluid inclusions in the quartz phenocrysts have homogenization temperatures of 260 380 c and salinities of 1 4 12 4 wt nacl equiv for liquid vapor type inclusions and 34 1 44 3 wt nacl equiv for brine ones the quartz phenocrysts exhibit homogeneous cathodoluminescence without growth bands or zoning the trace element contents in the quartz phenocrysts are extremely low ti 3 4 5 1 ppm al 13 118 ppm li

lattice preferred orientations of late variscan granitoids derived from neutron diffraction data implications for magma emplacement mechanisms the lattice preferred orientation lpos of two late variscan granitoids the meissen monzonite and the podlesi dyke granite were determined from high resolution time of flight neutron diffraction patterns gained at the diffractometer skat in dubna russia the results demonstrate that the method is suitable for the lpo analysis of polyphase relatively coarse grained 0 1 6 mm rocks the meissen monzonite has a prominent shape preferred orientation spo of the non equidimensional minerals feldspar mica and amphibole whereas spo of the podlesi granite is unapparent at the hand specimen scale the neutron diffraction data revealed distinct lpos in both granitoids the lpo of the non equidimensional minerals feldspar mica and amphibole developed mainly during magmatic flow in the case of the meissen monzonite the magmatic flow was superimposed by regional shear tectonics which however had no significant effect on the lpos in both samples quartz shows a weak but distinct lpo which is atypical for plastic deformation and different in the syn kinematic meissen monzonite and the post kinematic podlesi granite we suggest that first of all the quartz lpo of the meissen monzonite is the result of oriented growth in an anisotropic stress field the quartz lpo of the podlesi granite which more or less resembles a deformational lpo in the flattening field of the local strain field developed during magmatic flow whereby the rhombohedral faces of the quartz crystals adhered to the 010 faces of aligned albite and to the 001 faces of zinnwaldite due to shape anisotropy of their attachments the quartz crystals were passively aligned by magmatic flow thus magmatic flow and oriented crystal growth are the major lpo forming processes in both granitoids for the meissen monzonite the solid state flow was too weak to cause significant crystallographic re orientation of the minerals aligned by magmatic flow finally the significance of our results for the evaluation of the regional tectonic environment during magma emplacement is discussed the discussion on the regional implications of the more methodologically oriented results provides the basis for future more regionally aimed studies in view of the fabric characteristics of such plutons and their developing mechanisms

decryption of igneous rock textures crystal size distribution tools in this overview it is planned to show how quantitative determination of mineral modes data by means of crystal size distribution csd may help in deciphering the kinetics of magmatic crystallization both in natural and experimental conditions some stereological considerations will be discussed to provide criteria for the choice of numbers and lengths of size intervals for csd computations equations for the balance of number and size of crystals in steady state crystallization and in dynamic regime will be used to define the time frame of magmatic processes in the context of the case studies of stromboli and etna volcanoes the functional dependence of crystal size l and crystal number from time is explicitly derived by interpreting experiments of olivine crystallization that report csd data thus obtaining evaluation of thermodynamic parameters from csd measurements

local amplification of rayleigh waves in the continental united states observed on the usarray abstract we develop a method based on ratios of amplitudes measured at adjacent stations to determine local amplification of surface waves across an array of seismic stations we isolate the effects of local structure from those of the earthquake and propagation by systematic averaging of ratios corresponding to many sources we apply the method to data recorded on the usarray for the years 2006 2011 and determine amplification factors at each station of the array for rayleigh waves at periods between 35 s and 125 s local amplification factors are spatially coherent and display variations of 10 at a period of 125 s and greater variations at shorter periods maps of local amplification exhibit spatial correlation with topography and geologic structures in the western and central united states at long periods the observed amplification factors correlate well with predictions from a regional crust and mantle model of north america at short periods correlations are weaker suggesting that the local amplification factors can be useful for constraining shallow structure better

metallogeny of the syenite related dongping gold deposit in the northern part of the north china craton a review and synthesis abstract the dongping gold deposit is located at the northern margin of the north china craton in hebei province china it is the largest alkaline pluton related au deposit in china the ore deposit is hosted in the 400 386 ma la icpms and shrimp zircon u pb method shuiquangou syenite intrusion which cuts archean aged metamorphic rocks the ore bodies consist of a set of en echelon lenses and veins controlled by shear zones the ores can be divided into auriferous quartz vein stockwork and disseminated ores two stages of gold mineralization can be distinguished the first stage mineralization consists of high grade 10 g t grayish quartz veins enveloped by stockwork and disseminated ores whereas the second stage mineralization occurs as low grade studies of fluid inclusions in quartz indicate that the ore forming fluids have low salinity 0 7 8 1 nacl equivalent in the h2o co2 nacl system and have homogenization temperatures varying from 310 to 350 c the ore forming fluids have 18o values varying from 1 7 to 6 9 with an average of 2 9 and d values from 108 to 66 5 with an average of 85 indicating a magmatic origin with some involvement of meteoric fluid the ore forming fluids have initial 87sr 86sr385ma ratios of 0 705 0 706 and 3he 4he ratios of 0 3 to 5 2 ra ra being the atmospheric ratio of 1 0 indicative of a mantle contribution of the fluids the ores have bulk 34s values varying from 1 to 2 similar to those of the host syenites 34s 1 8 3 and the archean metamorphic rocks 34s 0 04 to 4 4 lead isotope analyses of sulfides stock and disseminated ores quartz veins fresh host syenites and the archean metamorphic rocks have a linear correlation of 208pb 206pb and 207pb 206pb indicating a genetic link between the gold mineralization and the syenites hydrothermal zircons from the high grade ores of the first stage can be distinguished from magmatic zircons based on internal textures on cathodoluminescence images and rare earth element patterns these zircons have been dated at 389 1 0 to 385 5 7 ma whereas those from the second stage low grade auriferous quartz vein were dated at 140 ma la icpms and sim u pb methods we propose a model for the formation of the dongping gold deposit involving a late magmatic hydrothermal process related to a devonian mantle sourced syenites with a late jurassic early cretaceous hydrothermal overprint

isopycnal mixing in ocean circulation models abstract a subgrid scale form for mesoscale eddy mixing on isopycnal surfaces is proposed for use in non eddy resolving ocean circulation models the mixing is applied in isopycnal coordinates to isopycnal layer thickness or inverse density gradient as well as to passive scalars temperature and salinity the transformation of these mixing forms to physical coordinates is also presented

shear wave attenuation and dispersion in melt bearing olivine polycrystals 2 microstructural interpretation and seismological implications 1 the torsional forced oscillation tests of melt bearing olivine aggregates reported by jackson et al 2004 consistently show a peak in attenuation that is absent from melt free aggregates tested under similar conditions and grain sizes characterization by sem shows that the melt resides in triple junction tubules and larger pockets as previously described tem imaging and eds analysis reveals that olivine olivine grain boundaries are characterized by a region 1 nm wide which is structurally and chemically distinct from olivine grain interiors from the possible mechanisms that can produce an anelastic attenuation peak melt squirt can be eliminated for our samples and experimental conditions we attribute the observed attenuation peak to elastically accommodated grain boundary sliding requiring that the grain boundaries are weak relative to olivine grain interiors but have a significantly higher viscosity than bulk melt while the nanometer scale grain boundary structure in the melt bearing aggregates is essentially the same as for melt free aggregates studied previously elastically accommodated sliding in the latter is apparently inhibited by tight three grain edge intersections the exponentially increasing high temperature background attenuation in both types of aggregate is attributed to diffusionally accommodated grain boundary sliding extrapolation to mantle grain sizes shows that the broad peak may be responsible for nearly frequency independent attenuation in partially molten regions of the upper mantle

crystallographic orientation of microcracks in quartz and inferred deformation processes a study on gneisses from the german continental deep drilling project ktb abstract this study was carried out on four gneiss samples from the german continental deep drilling project ktb taken at depths between 556 and 8633 m the crystallographic orientation of microcracks in quartz was determined by a combination of the electron channelling pattern method ecp and u stage microscopy the distinct preferred crystallographic orientations of various crack generations point to different processes of crack initiation and propagation which partly seem to be depth dependent for older healed cracks a crystalplastic initiation due to dislocation pile up and related lattice distortion is indicated by cracking normal to prominent slip directions which are a at lower or c at comparatively higher temperatures in contrast younger open cracks preferentially formed on crystallographic planes with low surface energy rhombs and prisms which is interpreted in terms of pure elastic crack mechanisms because of the thermoelastic anisotropy of quartz internal stresses resulting from thermal contraction during cooling may be the main driving force for the initiation or further propagation of cracks parallel to the c axis crack propagation preferentially affects grains with crystal lattices and operating crack mechanisms being in a direction appropriate to the applied external tectonic stresses this selective cracking explains why cracks also show constant orientations with respect to geographic directions up to regional dimensions

petrology and geochemistry of the shuiquangou syenitic complex northern margin of the north china craton the palaeozoic shuiquangou complex is a major syenitic intrusion along the northern margin of the north china craton that hosts a number of gold deposits despite the heterogeneity of the complex in terms of texture and modal mineralogy mineral compositions whole rock chemistry as well as radiogenic isotope compositions show a well constrained magmatic evolutionary trend the whole rock major element and ree trends are broadly consistent with fractional crystallization dominated by clinopyroxene amphibole and accessory minerals initial nd sr isotopic compositions suggest that the parent magmas to the complex were ultimately derived from an enriched mantle with relatively high initial 87 sr 86 sr ratios and negative nd values the enrichment of the mantle source was probably inherited from an older lithospheric mantle beneath the north china craton sr isotopic data indicate that the rb sr system was disturbed by later alteration processes whereas nd isotopes are essentially unaffected and exhibit a broad trend consistent with simultaneous fractional crystallization and country rock assimilation afc quantitative modelling indicates that a very high bulk distribution coefficient for nd and low ratios of assimilation to crystallization are needed to produce the observed nd isotope evolutionary trend

the upper mantle degree 2 constraints and inferences from global mantle wave attenuation measurements we present the results of an analysis of global lateral variations in anelasticity of the upper mantle as measured from very long period rayleigh waves observed on the geoscope network four consecutive wave trains are used on each record to eliminate uncertainty on the amplitude at the source and to take into account in a linear manner focussing effects due to lateral variations in elastic parameters local estimates of attenuation are obtained using an inversion method based on the introduction of a correlation length as an alternative to spherical harmonics expansion comparison of phase velocity and attenuation maps obtained at various periods shows a strong correlation of high q and high velocity regions respectively low q and low velocity both for great circle and minor arc data at periods around 200 s the detailed analysis of the degree 2 pattern well resolved in the attenuation maps around this period shows that it originates in the depth range 250 500 km and indicates that of the upper mantle degree 2 pattern observed in shear velocity is likely to be of thermal origin possibly related to the topmost part of the large scale convective system corrections for dispersion due to anelastic attenuation in degree 2 lead to significant decrease of corresponding lateral variations in shear velocity and a better agreement in phase and amplitude of the upper mantle degree 2 pattern with that observed in the geoid this study shows that it is important to consider correcting presently available upper mantle tomographic models for the effects of intrinsic attenuation at long periods before performing any comparison with short period data or other geophysical parameters

love and rayleigh phase velocity maps 5 40 s of the western and central usa from usarray data abstract continuous data recorded on more than 1600 usarray seismic stations operating in the western and central us between 2006 and 2012 are used to map phase velocities of love and rayleigh waves at short periods 5 40 s using a noise correlation technique vertical and transverse records for all station pairs separated by less than 600 km are cross correlated in 4 h long segments and the resulting spectra are stacked for the time period of station operation dispersion curves are determined from the locations of zeros in the real component of the correlation spectra using a method based on that of aki 1957 phase velocity maps expanded on a 0 25 by 0 25 pixel grid are estimated by inversion of the phase velocity measurements comparison with predicted phase velocity maps based on the crustal model crust2 0 combined with the mantle model nd08 shows good agreement at the longer periods strong slow anomalies 25 in the short period maps are geographically correlated with basins and regions of thick sedimentary cover the strength of these anomalies is not well predicted by existing crustal velocity models

stable isotope and fluid inclusion constraints on the source and evolution of ore fluids in the hongniu hongshan cu skarn deposit yunnan province china the hongniu hongshan cu skarn deposit 77 8 mt at 1 8 cu is located in the central part of the zhongdian porphyry and skarn cu belt in southwestern china skarn and orebodies occur mainly between the different units of the upper triassic qugasi formation or within altered limestone adjacent to late cretaceous intrusions 78 76 ma three main paragenetic stages of skarn formation and ore deposition have been recognized on the basis of petrographic observations 1 pre ore stage hornfels with diopside di87 72hd12 7 small scale endoskarn with reddish grossular adr22 57gr78 43 diopside di83 92hd7 15 vesuvianite and abundant exoskarn with red brown andradite adr75 98gr2 22 sahlite di28 41hd58 71 and wollastonite 2 syn ore stage retrograde minerals sulfides pyrite chalcopyrite pyrrhotite molybdenite galena and sphalerite quartz and calcite and 3 post ore stage calcite veins sulfur isotope values of sulfides are relatively high with an average 34s 4 9 n 40 suggesting that the ore forming fluid was magmatic and that the sulfides precipitated from a relatively reducing ore fluid the coexistence of silicate melt and primary fluid inclusions in quartz phenocrysts of the mineralization related quartz monzonite porphyry indicates the simultaneous entrapment of fluid and melt and records the process of the aqueous fluid exsolving from the crystallizing melt the initial single phase fluid has a salinity of 8 8 to 12 7 wt nacl equiv and homogenization temperatures of 566 to 650 c corresponding to pressures of 680 to 940 bar and lithostatic depth of 2 5 to 3 5 km the primary fluid inclusions in the pre ore stage garnet and pyroxene composed of coeval vapor rich v type and halite bearing s i and s ii types containing sylvite inclusions 32 79 total wt salts share similar homogenization temperatures 450 550 c indicative of the occurrence of fluid unmixing under lithostatic pressures of 550 to 780 bar 2 0 km depth primary fluid inclusions trapped in syn ore quartz calcite and epidote show the common development of s type inclusions 37 3 wt nacl equiv with coexisting v type liquid rich l type and co2 bearing c i type inclusions all of which have homogenization temperatures of 300 to 400 c and trapping pressures of 100 to 400 bar 1 5 km depth brine inclusions homogenized by halite dissolution after vapor disappearance in both the pre and syn ore stages are interpreted to have been trapped under overpressured conditions 1 520 bar oxygen isotope analyses were conducted on garnet wollastonite epidote quartz and calcite the pre ore stage garnet and wollastonite have 18ofluid values of 5 6 to 8 1 whereas the syn ore stage epidote quartz and calcite have more variable 18ofluid values in the range of 3 9 to 17 5 the 18ofluid values of the post ore stage vein calcite 15 2 21 3 are much higher than both the pre and syn ore stages the vapor phase of inclusions contains h2s ch4 and c2h6 in the syn ore stages all these observations reveal that 1 the formation of the cu skarn deposit was dominated by a magmatic hydrothermal system 2 multiple fluid pulses contributed to the formation of the pre and syn ore stage skarn minerals and sulfides and 3 the increase in ph due to the neutralization of the acidic fluid could be the main factor controlling the large scale ore deposition in hongniu hongshan

role of resolved and parameterized eddies in the labrador sea balance of heat and buoyancy abstractdeep convection in the labrador sea is an important component of the global ocean ventilation the associated loss of heat to the atmosphere from the interior of the sea is thought to be mostly supplied by mesoscale eddies generated either remotely or as a result of convection itself processes that are not resolved by low resolution ocean climate models the authors first employ a high resolution ocean model forced with high resolution 33 km 3 h atmospheric fields to further elaborate on the role of mesoscale eddies in maintaining the balance of heat and buoyancy in the labrador sea in general agreement with previous studies it is found that eddies remove heat along the coast and supply it to the interior some of the eddies that are generated because of the barotropic instability off the west coast of greenland are recaptured by the boundary current in the region of deep convection the convergence of heat and buoyancy by eddies significantly increases with the deepening of the winter

trace element composition of quartz from the variscan altenberg teplice caldera krusne hory erzgebirge mts czech republic germany insights into the volcano plutonic complex evolution abstract in this study the internal structures and appropriate trace element distributions within quartz grains were investigated using a laser ablation icp ms technique combined with a hot cathode and scanning cathodoluminescence analysis the studied variscan magmatic suite is located in the altenberg teplice caldera eastern krusne hory erzebirge along the czech republic germany border and composed of co magmatic volcanics peraluminous basal rhyolite and associated dacite overlying three units of subaluminous teplice rhyolite and granite porphyry and plutonic granites two intrusions of a type biotite and zinnwaldite granites the trace element distribution in the granite porphyry and rhyolite quartz demonstrates a distinct zoning in the cathodoluminescence images and chemical compositions the core is poor in ti the outer rim zones are enriched in ti and the trends recorded for al are opposite to those of ti the quartz from granites is either very weakly zoned or homogeneous based on the chemical composition of quartz and its zoning we assume that the quartz crystals began to crystallize gradually in the primary deep seated magma chamber with a p t condition of 10 kbar and 750 c and in an environment with an increasing concentration of al and decreasing concentration of ti the early stage was followed by the subsequent adiabatic ascent into a shallow magma chamber estimated by the ti in quartz thermobarometry at approximately 700 c 2 kbar during which crystal rims rich in ti formed and then extruded after the caldera collapse part of the magma intruded as granite and in the environment of the residual melt rich in water and flux agents late quartz grew in the form of snowball quartz with an increased al content and decreased ti content

evolution and formation of north atlantic eighteen degree water in the sargasso sea from moored data abstract two profiling subsurface moorings were deployed as part of the clivar mode water dynamics experiment climode to study the formation and evolution of eighteen degree water edw from november 2006 to november 2007 both moorings were deployed south of the gulf stream in the edw outcrop region the northwestern part of the subtropical gyre of the north atlantic the two moorings captured the seasonal evolution of edw characterized by gradual mixed layer deepening and wintertime outcrop rapid restratification from may to june and slower dissipation during the rest of the year superimposed on this seasonal cycle the moored records are characterized by high frequency passing of eddies with a characteristic time scale of 10 days i e it took about 10 days for eddies to pass the mooring sites the net impact of these eddy fluxes is evaluated by analyzing one dimensional heat and salt budgets of the upper ocean at the moorings and comparing them to the local air sea fluxes it is shown that oceanic lateral fluxes converge heat and salt into the formation region during winter thus offsetting the heat loss to the atmosphere and influencing the formation of edw a comparison with results from a one dimensional model shows that without the lateral fluxes edw would outcrop earlier and it would be colder and fresher the warm salty waters transported into the region originate from the gulf stream and this suggests that frontal processes likely play a fundamental role in edw formation and its evolution

evaluation of the quartz eye hypothesis deformed rocks containing quartz eyes are common in mining areas and a correct interpretation of the origin of the quartz eyes is important for evaluating models for ore genesis especially volcanogenic models reexamination of the literature provides little or no support for the hypothesis that large embayed quartz grains quartz eyes that resemble phenocrysts and that occur in fine grained generally foliated aggregates are porphyroblasts quartz phenocrysts in deformed volcanic or volcaniclastic rocks can remain undeformed even though the surrounding fine grained matrix has undergone extensive deformation and recrystallization therefore most if not all quartz eyes should be interpreted as residual phenocrysts

behavior of trace elements in quartz from plutons of different geochemical signature a case study from the bohemian massif czech republic article i nfo in this study the trace element content in igneous quartz from granitoids of different geochemical types was investigated using the laser ablation icp ms technique the variscan granitoids in the bohemian massif pro vide an excellent opportunity to study the chemical composition of magmatic quartz from the following granite types 1 geochemically primitive i type tonalites and granodiorites 2 peraluminous s type two mica granites 3 moderately fractionated a type volcano plutonic complexes of the teplice caldera and 4 highly fractionated s and a type rare metal granites this diversity of granitoids permitted the study of the chemical composition of magmatic quartz as the result of i different magma protoliths and ii variable degrees of differentiation there were only small differences in the quartz trace element con tents ranging from weakly to moderately differentiated plutons of all geochemical types al mostly in the range between 20 and 250 ppm ti mostly 20 110 ppm b b13 ppm be b0 7 ppm ge b1 ppm li b30 ppm and rb b2 ppm only the s type granites from western erzgebirge contain al enriched quartz mostly 200 400 ppm al since the beginning of its evolution however quartz from the highly fractionated granites group 4 differs significantly this quartz is generally poor in ti b20 ppm ti and enriched in al up to 600 ppm in a type and up to 1000 ppm in s type granites be up to 3 2 ppm ge up to 5 7 ppm li up to 132 ppm particularly in the s type granites and rb up to 15 ppm the contents of the analyzed lithophile elements in the quartz from the highly fractionated granites are similar to the contents reported to be present in evolved complex pegmatites although the input of ti into quartz is controlled mainly by the temperature and pressure of quartz crystallization the entry of al into quartz increases as a function of the water and fluorine content of the residual melt the contents of ge and li increase significantly with the fractionation of parental melt the concentrations of these elements in quartz from highly fractionated granites are controlled by the order of crystallization of the major minerals comb quartz crystallizing before li mica is strongly li enriched whereas groundmass and snowball quartz crystallizing after mica is relatively enriched in ge