the mechanics of continental extension in western north america implications for the magmatic and structural evolution of the great basin abstract a finite element model of continental extension within a rheologically stratified lithosphere is used to examine the structural and magmatic consequences of extensional collapse of thickened crust within the early tertiary north american cordillera crustal thickening creates a weakness in the upper mantle in the model which focuses strain within the great basin during extension marginal highlands corresponding to the sierra nevada and colorado plateau develop near the edges of the weakened region where abrupt changes in the strength of the lithosphere create large gradients in the amount of strain the great thickness of the crust results in widespread ductile flow in the lower crust within the interior of the great basin favoring the formation of metamorphic core complexes during the early stages of extension ductile flow becomes inhibited as the crust thins and cools possibly contributing to the change in the style of extension from low angle detachment faulting to high angle normal faulting during the middle miocene as the lithosphere cools the strength of the uppermost mantle increases after about 10 m y the upper mantle becomes stronger beneath the great basin than beneath adjacent unextended regions strain then begins to migrate outward from the interior of the great basin onto the marginal highlands and their interior edges begin to collapse and are incorporated into the widening great basin after 40 m y of extension the highest rates of strain are localized at the edges of the great basin in positions corresponding to the walker lane tectonic belt of western nevada and the colorado plateau transition zone the weight of the marginal highlands in the model is partially supported by flexure of the strong layer in the uppermost mantle portions of the uppermost mantle which have been flexed upward cool more rapidly than deeper portions creating periodical variations in the strength of the lithosphere which eventually develop into crustal and lithospheric boudinage with a wavelength similar to that observed in regional gravity studies rapid thinning of the model lithosphere during the first 10 m y of extension results in nearly adiabatic decompression of the lithospheric mantle partial melting of the lower lithospheric mantle is likely during this period if volatile phases or mafic lithologies were present this mechanism may account for widespread silicic magmatism in the great basin during the middle tertiary as the region undergoing extension widens the rate of lithospheric thinning decreases and the mantle beneath the great basin begins to cool this leads to a cessation of melting within the lithosphere and waning of silicic volcanism 15 20 m y after the onset of extension the appearance of predominantly basaltic and bimodal volcanic suites in the great basin during the last 5 10 ma correlates well with the onset of decompression melting in the asthenosphere if the mantle potential temperature is greater than about 1350 c approximately 70 c warmer than typical mantle potential temperature

mineralogical controls on mine drainage of the abandoned ervedosa tin mine in north eastern portugal the ervedosa mine in north eastern portugal has sn bearing quartz veins containing cassiterite and sulphides that cut silurian schists and a sn bearing muscovite granite these veins were mined for sn and as2o3 until 1969 cassiterite the main sn ore has alternate lighter and darker growth zones the darker zones are richer in fe nb ta and ti but poorer in sn than the adjoining lighter zones exsolution blebs of ferrocolumbite manganocolumbite ti ixiolite rutile ilmenite and rare wolframite were found in the darker zones arsenopyrite is the most abundant sulphide and contains inclusions of pyrrhotite bismuth bismuthinite and matildite other sulphides are pyrite sphalerite chalcopyrite and stannite secondary solid phases consisting mainly of hydrate sulphate complexes of al fe ca and mg aluminocopiapite copiapite halotrichite pickeringite gypsum and alunogen meta alunogen occur at the surface of the sn bearing quartz veins and their wall rocks granite and schist while oxides hydroxides arsenates and residual mineral phases albite muscovite and quartz occur in mining tailings toxic acid mine waters acid mine drainage amd which have high conductivity and significant concentrations of as so4 and metal cu zn pb fe mn cd ni and co occur in an area directly affected by the mine surface stream waters outside this area have low conductivity and a ph that is almost neutral metal and as concentrations are also lower stream waters within the impact area have an intermediate composition falling between that of the amd and the natural stream waters outside impact area waters associated directly with mineralised veins must not be used for human consumption or agriculture

estimation of debris flow triggering rainfall influence of rain gauge density and interpolation methods abstract the forecast of debris flow occurrence relies mainly on empirical rainfall intensity duration thresholds which are based on rain gauge observations this work focuses on the effect of rainfall estimation uncertainty on the estimation of debris flow triggering rainfall events and on the identification of rainfall thresholds for debris flow occurrence specifically the influence of rain gauge network density and the interpolation method on the estimation of debris flow triggering rainfall is investigated these questions are examined using high resolution carefully corrected radar data to represent space time patterns of true precipitation at the debris flow initiation points and in the surrounding area radar rainfall fields are sampled by simulated rain gauge networks stochastically generated with varying rain gauge densities based on these networks rainfall is estimated by using three rainfall interpolation methods nearest neighbor nn inverse distance weighting idw and ordinary kriging ok results show that nn provides the estimates with bias smaller than idw and ok but larger estimation variance overall decrease in gauge density leads to increased underestimation and increased estimation variance of debris flow triggering rainfall rainfall estimation error leads to large underestimation of the intensity duration thresholds however comparison of results shows that no particular benefit in intensity duration threshold estimation is obtained by using approaches that are more complex than the nn method

postprocessing model predicted rainfall fields in the spectral domain using phase information from radar observations abstractin an attempt to combine the short term skill of radar nowcasting and the long term skill of numerical models successive 15 min rainfall accumulations obtained from the u s national radar composites and predicted by the weather research and forecasting wrf model are corrected by adjusting the phases of fourier components in the spectral domain while keeping the amplitudes invariant the phase information is first obtained by decomposing the radar and model fields into fourier space then to correct the model outputs a new set of fourier components is constructed using the phases from the radar image and amplitudes from the model image the corrected model image can be obtained by inverse transformation of the new set of fourier components scales of wavelengths starting from 50 to 500 km are playing a crucial role in correcting the positional and intensity errors of continental scale precipitating systems predicted by the wrf model while scales greater than 500 km are contributing very litt

a geochemical characterization of cold water natural acid rock drainage at the zn pb xy deposit yukon canada abstract acid rock drainage ard is considered to be temperature limited due to the diminished activity of fe ii oxidizing microbes at low temperatures nonetheless ard streams are present in cold climates this study presents a geochemical characterization of a cold climate ard creek at the zn pb xy deposit in yukon canada which showed highly elevated concentrations of dissolved zinc up to 475 mg l acid rock drainage at the xy deposit is likely generated via subsurface abiotic and biotic oxidation of sulfide minerals and then exits as seeps at the headwaters of the creek the uppermost reaches of the creek have the lowest ph levels ph 3 3 and highest metal concentrations with prolific precipitation of iron hydroxysulfate and oxyhydroxide mineral precipitates schwertmannite jarosite and goethite present as terraced iron formations tifs at one sampling location the lower reaches of the creek show a progressive ph increase up to ph level 4 9 which occurs due to fe iii and al hydrolysis the neutralizing influence of carbonate rich strata and or ground waters and dilution by surface waters entering the creek progressive ph neutralization causes a change in precipitate mineralogy to x ray amorphous al hydroxysulfates with a composition similar to aluminite and hydrobasaluminite and amorphous al oh 3 natural attenuation of cd zn and pb occurred downstream from the headwater seeps which was likely influenced by adsorption reactions involving both metal sulfate anions and metal sulfate ternary complexes generally the concentrations of cd zn and pb in the mineral precipitates followed trends in ph aqueous concentration predicted speciation and mineralogy of the precipitates however anomalous trace metal concentrations were observed in the precipitates at 120 m downstream and potentially reflect a local ground water input overall the geochemistry of this cold climate ard creek was similar to ard in more temperate climates although low temperatures appear to retard the kinetics of ferrous iron oxidation and seasonal hydrodynamics may influence the formation of tifs in these highly saturated waters

results of the basin and range geoscientific experiment barge a marine style seismic reflection survey across the eastern boundary of the central basin and range province approximately 120 km of marine style deep seismic reflection data were shot during a survey on the waters of lake mead in southeastern nevada the survey extends from near the abrupt eastern edge of the basin and range province brp to a point 80 km into the extended domain data quality throughout the survey ranged from fair to poor the recorded data include significant towing noise and occasionally problematic diffractions and sideswipe from canyon walls the upper 2 4 s of the data shows well defined reflections from sedimentary fill but below that point reflectivity is weak lower crustal reflectivity is generally absent under the eastern part of the survey with a slight increase in reflectivity to the west the reflection moho appears as a series of weakly defined discontinuous reflections most of which occur at 10 11 s a particularly interesting feature of the data set is the relative lack of reflectivity from the lower crust which is a region of strong reflectivity on other seismic reflection data sets from the brp

intracrustal complexity in the united states midcontinent preliminary results from cocorp surveys in northeastern kansas unusually clear indications of complex structure in the mid to lower crust is revealed by seismic reflection surveys in northeastern kansas this complexity contrasts markedly with the layer cake simplicity of both the overlying sedimentary cover and most previous crustal models for the central united states seismic sections collected by cocorp consortium for continental reflection profiling as part of a major east west traverse across the neniaha ridge and midcontinent geophysical anomaly indicate that below a thin relatively flat layered paleozoic sedimentary section the deep crust is characterized by numerous dipping and arcuate reflections and diffractions in many places layered and crosscutting these reflections suggest convoluted three dimensional folded faulted and intruded structures specific identification of these deep features may be possible if future surveys can trace them to accessible depths the basement above these reflection complexes contains significantly fewer reflections consistent with but not necessarily diagnostic of the granitic terrane that dominates basement drill hole samples in the region among the events at these shallower basement depths are several east dipping reflections some of which may be major faults travel times corresponding to expected moho depths about 36 km are characterized less by specific reflections than by an apparent decrease in the density and number of reflections while evidence of crustal heterogeneity is common among deep reflection studies the kansas seismic results outlined in this brief report stand out as being unusually clear representations of such

crustal structure of the colorado plateau arizona application of new long offset seismic data analysis techniques the colorado plateau is a large crustal block in the southwestern united states that has been raised intact nearly 2 km above sea level since cretaceous marine sediments were deposited on its surface controversy exists concerning the thickness of the plateau crust and the source of its buoyancy interpretations of seismic data collected on the plateau vary as to whether the crust is closer to 40 or 50 km thick a thick crust could support the observed topography of the colorado plateau isostatically while a thinner crust would indicate the presence of an underlying low density mantle this paper reports results on long offset seismic data collected during the 1989 segment of the u s geological survey pacific to arizona crustal experiment that extended from the transition zone into the colorado plateau in northwest arizona we apply two new methods to analyze long offset data that employ finite difference travel time calculations 1 a first arrival time inverter to find upper crustal velocity structure and 2 a forward modeling technique that allows the direct use of the inverted upper crustal solution in modeling secondary reflected arrivals we find that the crustal thickness increases from 30 km beneath the metamorphic core complexes in the southern basin and range province to about 42 km beneath the northern transition zone and southern colorado plateau margin we observe some crustal thinning to 37 km thick and slightly higher lower crustal velocities farther inboard beneath the kaibab uplift on the north rim of the grand canyon the crust thickens to a maximum of 48 km we observe a nonuniform crustal thickness beneath the colorado plateau that varies by 15 and corresponds approximately to variations in topography with the thickest crust underlying the highest elevations crustal compositions as inferred from seismic velocities appear to be the same beneath the colorado plateau as those in the basin and range province to the southwest implying that the plateau crust represents an unextended version of the basin and range some of the variability in crustal structure appears to correspond to preserved lithospheric discontinuities that date back to the proterozoic era

the mineralized veins and the impact of old mine workings on the environment at segura central portugal abstract at segura granitic pegmatite veins with cassiterite and lepidolite hydrothermal sn w quartz veins and ba pb zn quartz veins intruded the cambrian schist metagraywacke complex and hercynian granites cassiterite from sn w quartz veins is richer in ti and poorer in nb and nb ta than cassiterite from granitic pegmatite wolframite from sn w quartz veins is enriched in ferberite component the sn w quartz veins contain pyrrhotite arsenopyrite sphalerite chalcopyrite stannite matildite and schapbachite and the ba pb zn quartz veins have cobaltite pyrite sphalerite chalcopyrite galena and barite which were analyzed by electron microprobe the presently abandoned mining area was exploited for sn w ba and pb until 1953 stream sediments and soils have higher concentrations of metals than parent granites and schists sn w b as and cu anomalies found in stream sediments and soils are associated with sn w quartz veins while ba pb and zn anomalies in stream sediments and soils are related to ba pb zn quartz veins sn w b as cu ba pb and zn anomalies in stream sediments and soils are also related to the respective old mining activities which increased the mobility of trace metals from mineralized veins to soils stream sediments and waters stream sediments and soils are sinks of trace elements which depend on their contents in mineralized veins and weathering processes but sn w and b depend mainly on a mechanic process soils must not be used for agriculture and human residence due to their sn b as and ba contents waters associated with mineralized veins were analyzed by flame atomic absorption spectroscopy faas and icp aes have high as fe and mn and should not be used for human consumption and agriculture activities the highest as values in waters were all related to sn w quartz veins and the highest fe and mn values were associated with the ba pb zn quartz veins no significant acid drainage was found associated with the old mine workings

cocorp deep reflections moho at 50 km 16 s beneath the colorado plateau cocorp deep reflection data on the colorado plateau reveal complex reflections to about 16 s two way travel time 50 km beyond which there is an abrupt decrease of reflectivity this boundary is interpreted to represent the moho an inference consistent with the existing but limited refraction data sets when they are reconciled with the recent independent determination of an 8 10 8 15 km s pn velocity beneath the colorado plateau this 50 km depth to moho and 8 10 8 15 km s pn velocity for the colorado plateau closely resembles that of the high plains just east of the rocky mountains the absence of continuous strong reflections at the moho suggests that the moho beneath the colorado plateau is a transition not a velocity step function on the scale of the reflection experiment the reflection boundary may represent the base of complex and discontinuous reflectors of the crust and crust mantle transition below which the mantle may be largely peridotite with a velocity of 8 1 km s these results strongly reinforce the suggestion that the moho on deep reflection data in relatively stable continental regions is represented by an abrupt decrease in reflectivity below which the mantle is relatively seismically transparent

hydrochemistry mineralogy and chemical fractionation of mine and processing wastes associated with porphyry copper mines a case study from the sarcheshmeh mine se iran abstract the sarcheshmeh is one of the largest oligo miocene porphyry cu deposits in the world comparative hydrochemical mineralogical and chemical fractionation associated with mining efflorescence salts and processing wastes of this mine are discussed hydrochemical results showed that rock waste dumps reject wastes and old impoundments of tailings are the main sources of acid mine drainage waters amd that contain potentially toxic metals such as cd co cu mn ni and zn as well as al episodic fluxes of highly contaminated acidic waters were produced in a tailings dam over a short period of time secondary soluble minerals provide important controls on the quality of amd produced especially in old dry tailings impoundments secondary sulfate minerals such as gypsum magnesiocopiapite hydronium jarosite kornelite and coquimbite were found in rock waste drainages and in old weathered reject wastes highly soluble secondary minerals such as gypsum eriochalcite and bonattite are also observed in an evaporative layer on old tailings impoundments chemical fractionation patterns of potentially toxic elements showed that the geochemical behavior of metals is primarily controlled by the mineralogical composition of waste samples elements such as co cr cu mn ni and zn are readily released into the water soluble fraction from efflorescence salts associated with rock waste drainages as well as from the evaporative layer of old tailings potentially toxic elements such as as mo and pb are principally adsorbed or co precipitated with amorphous and crystalline fe oxides but they may also be associated with oxidizing primary sulfides and residual fractions following the development of the dammed tailings pond the secondary minerals were dissolved producing acidic waters contaminated by al 154 mg l 1 cu 150 mg l 1 cd 0 31 m gl 1 co 2 13 mg l 1 mn 73 7 mg l 1 ni 1 74 mg l 1 zn 20 3 mg l 1 and cl 1690 mg l 1 therefore the potential use of recycled water from the sarcheshmenh dammed tailings pond is diminished by the presence of corrosive ions like cl in highly acidic fluids that promote corrosion of pipes and pumps in the water recycling system

crustal structure and evolution beneath the colorado plateau and the southern basin and range province results from receiver function and gravity studies over the past several decades contrasting models have been proposed for the physical and chemical processes responsible for the uplift and long term stability of the colorado plateau cp and crustal thinning beneath the basin and range province brp in the southwestern united states here we provide new constraints on the models by modeling gravity anomalies and by systematically analyzing over 15 500 p to s receiver functions recorded at 72 usarray and other broadband seismic stations on the southwestern cp and the southern brp our results reveal that the brp is characterized by a thin crust 28 2 0 5 km a mean vp vs of 1 761 0 014 and a mean amplitude r of p to s converted wave relative to that of the direct p wave of 0 181 0 014 that are similar to a typical continental crust consistent with the model that the thin crust was the consequence of lithospheric stretching during the cenozoic the cp is characterized by the thickest crust 42 3 0 8 km largest vp vs 1 825 0 009 and smallest r 0 105 0 007 values in the study area in addition many stations on the cp exhibit a clear arrival before the p to s converted phase from the moho corresponding to a lower crustal layer of about 12 km thick with a mafic composition we hypothesize that the lower crustal layer which has an anomalously large density as revealed by gravity modeling and high velocities in seismic refraction lines contributed to the long term stability and preuplift low elevation of the colorado plateau

the active southwest margin of the colorado plateau uplift of mantle origin during cenozoic time the colorado plateau was raised about 2 km above sea level the most recent and best documented uplift of the plateau 1 km has been concentratedatitssouthwestmarginbetween6 and 1 ma whereas the eastern colorado plateau may have been at high elevations sinceeocenetime tobetterunderstandthe recent tectonic activity at the southwest marginofthecoloradoplateau wecompile detailed crustal thickness and density informationfromseismicandgravitydatafor a region that includes northwest arizona and the southern tip of nevada this information is used to isolate the mantle contribution to uplift wefind that there is relatively low density mantle underlying the southernmarginoftheplateauinnorthwest arizona which could result from about 60 80 km of thinning of the dense mantle lithosphere combined with about 100 cof heating through a 100 km thick mantle layer the available estimates from earthquake source seismology in or near the studyareaarecompatiblewiththisestimate of lithospheric thinning we speculate that uplift may result from subduction related thinning of the continental lithosphere

mineral water interactions in tailings from a tungsten mine mount pleasant new brunswick abstract the pore water geochemistry and mineralogy of tailings derived from a granitic tungsten deposit were characterized by collecting pore water samples at discrete depth intervals throughout the tailings for the analysis of major and minor element concentrations mineralogical samples from the oxidation zone were analyzed by x ray diffraction scanning electron microscopy combined with energy dispersive x ray spectroscopy sem eds electron microprobe emp combined with wavelength dispersive x ray spectroscopy wds and transmission electron microscopy tem the oxidation of sulfide minerals in the near surface tailings leads to a decrease in pore water ph and elevated so 4 as and metal concentrations the unusual mineralogy of this deposit compared with that of commonly studied base metal and gold deposits results in several unique geochemical characteristics the dissolution of fluorite releases f into the pore water the f forms strong complexes with al and enhances the dissolution of aluminosilicate minerals within the oxidation zone as a result high al concentrations up to 151 7 mg l are detected in the near neutral pore water in the oxidation zone the combined dissolution of aluminosilicates and carbonate minerals maintains the ph near 10 in the pore water at depth elevated concentrations of w up to 7 1 mg l are detected in the pore water throughout the tailings likely as a result of the dissolution of wolframite consistent with geochemical model calculations results from sem eds emp wds and tem eds analyses indicate that secondary minerals which occur as orange brown coatings on grains of primary minerals are fe oxyhydroxides examples of these secondary minerals display a fibrous habit at high resolution in the tem one of these minerals which contains substantial amounts of al as and si as impurities was identified by selected area electron diffraction saed analyses to be goethite another mineral contains relatively high amounts of si pb bi and as and saed analyses suggest that the mineral is two line ferrihydrite

the stability of sulfate and hydrated sulfate minerals near ambient conditions and their significance in environmental and planetary sciences abstract sulfate and hydrated sulfate minerals are abundant and ubiquitous on the surface of the earth and also on other planets and their satellites the humidity buffer technique has been applied to study the stability of some of these minerals at 0 1 mpa in terms of temperature relative humidity space on the basis of hydration dehydration reversal experiments updated phase relations in the binary system mgso 4 h 2 o are presented as an example to show how reliable thermodynamic data for these minerals could be obtained based on these experimental results and thermodynamic principles this approach has been applied to sulfate and hydrated sulfate minerals of other metals including fe both ferrous and ferric zn ni co cd and cu metal sulfate salts play important roles in the cycling of metals and sulfate in terrestrial systems and the number of phases extends well beyond the simple sulfate salts that have thus far been investigated experimentally the oxidation of sulfide minerals particularly pyrite is a common process that initiates the formation of efflorescent metal sulfate minerals also the overall abundance of iron bearing sulfate salts in nature reflects the fact that the weathering of pyrite or pyrrhotite is the ultimate source for many of these phases many aspects of their environmental significance are reviewed particularly in acute effects to aquatic ecosystems related to the dissolution of sulfate salts during rain storms or snow melt events hydrous mg ca and fe sulfates were identified on mars with wide distribution and very large quantities at many locations on the basis of spectroscopic observations from orbital remote sensing and surface explorations by rovers however many of these findings do not reveal the detailed information on the degree of hydration that is essential for rigorous interpretation of the hydrologic history of mars laboratory experiments on stability fields reactions pathways and reaction rates of hydrous sulfates likely to be found on mars enhance our understanding of the degrees of hydration of various sulfates that should currently exist on mars at various seasons and locations and during various atmospheric pressure and obliquity periods two sets of systematic experiments were described one on hydrous mg sulfates and the other on hydrous fe 3 sulfates also their implications to mars sulfates mineralogy were discussed

moho beneath the north sea compared on normal incidence and wide angle seismic records the mohorovicic discontinuity the moho is properly defined as the step in the velocity of horizontally travelling p waves from about 7 km s 1 to about 8 1 km s 1 its detailed structure varies from place to place but it is universally interpreted as the transition from crust to mantle normal incidence reflections originating at about moho depth have been reported sporadi cally during the past 20 yr during the past 10 yr continuous seismic reflection profiles have been obtained to this depth both on the continents and in the deep sea and at the same time striking improvements have been made in the methods available for interpretation of refraction experiments here we report a comparison between the moho determined by a long range refraction experiment across the north sea and the results of a short normal incidence reflection profile shot along the same line fig 1 we believe this to be the first time that such a direct comparison has been made

acid mine drainage in the iberian pyrite belt odiel river watershed huelva sw spain geochemistry mineralogy and environmental implications abstract this work reports the physical properties and water chemistry of 64 amd discharges from 25 different mines in the ipb draining to the odiel river watershed which have been investigated during the hydrologic year 2003 2004 these amd solutions vary largely in flow rate and chemical composition both spatially between the different mine sites suggesting a strong geologic control on amd chemistry and seasonally due to marked hydrologic variations and include cases with very low ph mostly in the range 1 4 4 and extreme sulphate up to 44 g l so 4 2 and metal content e g up to 7 7 g l fe 2 6 g l al or 1 4 g l zn different hydrogeochemical facies of amd namely fe ii anoxic fe iii suboxic and aluminous oxic are recognized in the field as a response to the continuous oxidation and hydrolysis of dissolved fe relevant geochemical aspects of these amd environments are discussed including i the redox chemistry of the fe ii fe iii couple ii the reaction rates for bacterially catalyzed oxidation of fe ii and hydrolysis of fe iii iii the role played by dissolved fe and al in the acidity and chemical buffering of the amd systems and iv the solubility and trace metal retention capacity of the fe oxyhydroxysulphate and hydrated sulphate minerals commonly associated with amd in addition the mineralogy and chemistry of the fe precipitates schwertmannite jarosite goethite ferrihydrite al phases e g basaluminite and mg fe al efflorescent so4 salts e g epsomite hexahydrite copiapite halotrichite rozenite coquimbite present in the amd generating mine sites have also been studied the mineralogy of the fe precipitates is well correlated with the water ph with jarosite at ph 2 schwertmannite at ph 2 4 basaluminite at ph 4 5 and ferrihydrite at ph 6 schwertmannite appears to be the most important mineral phase both in controlling the fe solubility at ph 2 4 and as sorbent of trace elements as cu zn which favours natural attenuation finally a basin scale environmental perspective is given in order to evaluate the impact of amd on the water quality including calculation of metal loadings transported by amd from the most important mine districts in the province

application of multivariate statistical methods to indicate the origin and geochemical behavior of potentially hazardous elements in sediment around the sarcheshmeh copper mine se iran multivariate statistical techniques i e correlation coefficient analysis principal components analysis pca and hierarchical cluster analysis ca were applied to the total and water soluble concentrations of potentially hazardous metals in sediments associated with the sarcheshmeh mine one of the largest oligo miocene porphyry copper deposits in the world the samples were analyzed for hazardous metal concentration levels by inductively coupled plasma mass spectrometry method results indicate that the contaminant metals as cd cu mo s sb sn se pb and zn were positively correlated with the total concentrations these hazardous metals also have strong association in the pca and ca results different anthropic versus natural sources of contaminant metals were distinguished by using ca method water soluble fraction of hazardous metals showed that the hydro geochemical behavior of these metals in sediments is different considerably elements such as cd co cr cu fe mn ni s and zn are readily water soluble from contaminated samples especially from evaporative mineral phases while the release of as mo sb and pb into the water is limited by adsorption processes results obtained from the application of multivariate techniques on the water soluble fraction data set show that the hazardous metals are categorized into three groups including 1 ni s co cu cr and fe 2 se mn cd and zn and 3 sb as mo and sn this classification describes the hydro geochemical behavior of hazardous metals in water sediment environments of the sarcheshmeh porphyry copper mine and can be used as a basis in remedial and treatment strategies

deep structure of the scottish caledonides revealed by the moist reflection profile the moine and outer isles seismic traverse moist is a deep crustal reflection profile shot at sea off the north coast of scotland in 1981 spectacular reflections are observed from the moho and from thrust zones within the caledonian fold belt and foreland deep reflection profiling of the continental crust of the united states under the direction of the cocorp group has amply demonstrated the value of this technique when applied to suitable geological problems see for example refs 1 2 a similar group the british institutes reflection profiling syndicate birps has now been set up in the uk to organize such projects funds are provided by the natural environment research council nerc through the core group based at cambridge university however a preliminary experiment of which moist is the result was organized through the institute of geological sciences igs

crust and mantle structure across the basin and range colorado plateau boundary at 37 n latitude and implications for cenozoic extensional mechanism we present new evidence on the seismic velocity and density of the crust and upper mantle along a 200 km long transect across the eastern basin and range and western colorado plateau at 37 n latitude receiver functions computed from the p waveforms recorded with 10 portable broadband stations deployed along the transect were used to estimate crustal thickness variations the crust is 30 35 km thick within the eastern basin and range and increases over a distance of 100 km at the western edge of the colorado plateau reaching a maximum of approximately 45 km east of the hurricane fault the timing of crustal multiples within the reciever functions were used to estimate the v p v s of the crust along the profile and we found that the western colorado plateau crust is characterized by a high poisson s ratio 0 28 0 29 indicative of a crust with an average mafic composition we estimated the upper mantle lid thickness along our profile based on teleseismic p wave travel times and constraints provided by gravity data our data and available geophysical constraints are most consistent with a lithosphere that thickens from an average thickness of 60 km beneath the basin and range to 100 km beneath the western colorado plateau although the basin and range lithosphere may have significant thickness variations the thick strong mafic crust and thicker mantle lid under the colorado plateau can account for the relative geologic stability and subdued magmatism of the plateau during laramide compression and cenozoic extension compared to surrounding regions the crustal and lithospheric thinning across the tectonic boundary occurs over a short distance 100 km suggesting it is a geologically young feature produced by a predominantly mechanical response to late cenozoic extension our new lithosphere model at 37 n latitude is consistent with the existence in early cenozoic time of a flat subducted slab at 100 km depth and a relict sevier laramide 50 60 km thick crustal welt and 60 100 pure shear extension values of 1 6 2 0 during the late cenozoic

high resolution rainfall measurements by radar for very small basins the sampling problem reexamined abstract the dependence of the accuracy of short period radar rainfall accumulations on periodic sampling of the rainfield is investigated it is shown that errors due to sampling can be greater than all the other errors combined if accumulations are improperly computed however if the movement and the development of the storms are taken into account these errors can be reduced dramatically using an accumulation method taking storm movement and evolution into account the space and time resolution of radar maps resulting in the most accurate 5 min accumulations over areas smaller than 1 km 2 was determined it is shown that the best accumulations are obtained with very high time resolution data furthermore for a given time resolution there is an optimum spatial resolution that minimizes rainfall accumulation errors

using mesoscale model winds for correcting wind drift errors in radar estimates of surface rainfall summary for operational radars at middle and high latitudes even the lowest beam of a scan sequence may be above the melting layer for a considerable proportion of the total range this means that surface rainfall estimates are inferred from measurements made in the snow and ice snow and ice are more susceptible to wind drift than rain because of the low fall speed of around 1 m s 1 sampling these wind induced fall streak patterns results in a displacement of the radar rainfall eld when compared to ground measurements to date wind drift corrections have only been attempted in the rain but corrections of around 2 km are generally smaller than the resolution of the grid on which the rainfall eld is reported observational evidence from this study shows fall streaks in the snow can lead to displacements of the order of 10 20 km a signican t eect especially in colder climates and seasons in this paper a method for calculating and applying a wind drift correction between the top of the fall streak and the bright band height is presented the forecast wind prole from the mesoscale version of the uk met oce unied model um is used to calculate the vertical shear of the horizontal wind we assume the shear and the fall speed in the layer are constant results show that the method is able to reproduce observed displacements from high resolution radar data in the range height plane assessing the eect of applying the method in plan view shows an improvement in the placement of rainfall at the ground reected by an increase in the calculated skill scores the displacement can be corrected to within 20 this also shows that whereas wind drift corrections in the rain have been found to be insignican t corrections in the snow are not applying a wind drift correction also appears to reduce the variability of vertical proles of reectivit y vpr when they are extracted along a fall streak path and lead to a smaller reectivit y lapse rate locally this would suggest that at least part of the reported variability in vprs is due to wind eects

the crustal structure of the arizona transition zone and southern colorado plateau from multiobservable probabilistic inversion the arizona transition zone is a narrow band that separates two of the main and most contrasting tectonic provinces in western us namely the southern colorado plateau and the southern basin and range provinces as such the internal crustal structure and physical state of this transitional zone hold clues for understanding i the amalgamation of these provinces ii the partitioning of deformation due to both past and present day stress fields and iii the role of thermal versus compositional effects in controlling surface observables here we employ and expand a novel multiobservable probabilistic inversion method and jointly invert fundamental mode rayleigh phase velocities receiver functions surface heat flow geoid height and absolute elevation to obtain an internally consistent 3 d model of the temperature density vs and vp of the arizona transition zone and the southern portions of the colorado plateau and basin and range our results confirm a significant crustal thickening from 28 km in the sw of the arizona transition zone and southern basin and range to 48 km beneath the southern colorado plateau inverted temperatures agree well with the location of recent volcanism and indicate that the lithosphere asthenosphere boundary is not deeper than 70 km in most of the region we find that major pre cambrian surface structures and or shear zones separate crustal domains with distinct bulk properties suggesting that the juxtaposed crustal blocks still retain at least in part their original characteristics however widespread intrusions of significant volumes of mafic magmas have affected these blocks at different depths locally overprinting their original compositions and creating highly heterogeneous crustal sections a dominant and large scale internal crustal pattern of sw dipping planes structures is evident in our models coinciding with the orientation of deep faults previously inferred from earthquake focal mechanisms while we cannot categorically corroborate the presence of melt or aqueous fluids within the crust our results are compatible with these scenarios beneath some parts of the basin and range the mogollon datil and springerville volcanic fields

acid drainage from sulfides hosting gold mineralization furtei sardinia the past mining activity for kaolin minerals left several abandoned quarries in the area of furtei southern sardinia recently gold mineralization has been found in association with intensely altered andesitic rocks and an open pit gold mine is expected to open in the near future twenty one water samples were analyzed for a wide range of major and trace elements in order to define the present hydrochemical situation before exploitation starts waters interacting with the altered andesitic rocks had higher salinity and metal concentrations than waters in contact with nonaltered rocks acid drainage and high concentrations of metals al fe mn zn cu as in solution were observed in waters leaching the mineral deposit an environmental impact study is urgently called for since the waste material derived from the exploitation is expected to enhance acidification and metal releasing processes due to the increase in the specific yield which favors the oxidation of sufide minerals

cocorp arizona transect strong crustal reflections and offset moho beneath the transition zone the consortium for continental reflection profiling cocorp transect across the southwest margin of the colorado plateau in arizona reveals prominent subhorizontal zones of reflections here termed the bagdad reflection sequence brs which dominate the upper and middle crust in the transition zone tz between the colorado plateau and the basin and range province a cenozoic origin for the brs is considered most likely it may represent fragmented or sheared zones related to detachment faulting or a series of intrusions possibly emplaced along preexisting zones of weakness moho reflections observed beneath the tz and the basin and range province contrast with the nonreflective moho beneath the colorado plateau suggesting that extension and its associated igneous processes probably played a key role in the development of reflectors at the moho the moho and a prominent midcrustal reflector are offset by about 3 km in a normal sense in at least one place this is the best example of offset moho yet found by cocorp and contrasts sharply with cocorp observations of a smooth moho elsewhere this offset is probably a late tectonic expression of crustal extension and thinning across the tz

coincident seismic reflection refraction studies of the continental lithosphere a global review summary vertical incidence reflection profiling has identified several characteristic features of the continental iithosphere including a generally transparent upper crust a reflective lower crust reflections from the crust mantle boundary and a commonly transparent upper mantle the underlying physical causes of these characteristic features remain poorly understood this review summarizes additional information brought to bear on the physical properties of these characteristic crustal structures through the use of coincident wide angle refraction profiling

spatial estimation of debris flows triggering rainfall and its dependence on rainfall return period abstract forecasting the occurrence of debris flows is fundamental for issuing hazard warnings and often focuses on rainfall as a triggering agent and on the use of empirical rainfall thresholds based on rain gauge observations a recognized component of the uncertainty associated with the use of rainfall thresholds is related to the sampling of strongly varying rainfall variability with sparse rain gauge networks in this work we examine the spatial distribution of rainfall depth in areas up to 10 km from the debris flow initiation points as a function of return period and we exploit this information to analyze the errors expected in the estimation of debris flow triggering rainfall when rain gauge data are used in particular we investigate the impact of rain gauge density and of the use of different interpolation methods high resolution adjusted radar rainfall estimates representing the best available spatially distributed rainfall estimates at the debris flows initiation point and in the surrounding area are sampled by stochastically generated rain gauge networks characterized by varying densities debris flow triggering rainfall is estimated by means of three rainfall interpolation methods nearest neighbor inverse distance weighting and ordinary kriging on average triggering rainfall shows a local peak corresponding to the debris flow initiation point with a decay of rainfall with distance which increases with the return period of the triggering rainfall interpolation of the stochastically generated rain gauge measurements leads to an underestimation of the triggering rainfall that irrespective of the interpolation methods increases with the return period and decreases with the rain gauge density for small return period events and high rain gauge density the differences among the methods are minor with increasing the return period and decreasing the rain gauge density the nearest neighbor method is less biased because it makes use only of the closest rain gauge to the debris flow initiation point on the contrary inverse distance weighting and ordinary kriging which are using rain gauges located farther from the debris flows in addition to the closest one exhibit negative biases that increase with return period the standard deviation of the interpolated values is larger when the nearest neighbor is used with respect to inverse distance weighting and ordinary kriging for large return period and low rain gauge density the differences among the methods are minor

the role of secondary minerals in controlling the migration of arsenic and metals from high sulfide wastes berikul gold mine siberia abstract the role of secondary minerals in controlling the migration of as cu zn pb and cd has been investigated in piles of high sulfide waste at the berikul au mine kemerovo region russia these wastes contain 40 45 wt sulfides and have been stored for approximately 50 a near the mokry berikul river sulfide oxidation generates acid pore solutions ph 1 7 with high concentrations of so42 190 g l fe 57 g l as 22 g l zn 2 g l cu 0 4 g l pb 0 04 g l and cd 0 03 g l from these solutions as is precipitated as amorphous non stoichiometric fe sulfoarsenates in the lower horizons of the waste piles during precipitation of the fe sulfoarsenates the concentration of fe in these phases decreases from 34 to 21 wt that of as increases from 11 to 22 wt while the s content remains approximately constant 5 4 5 8 wt arsenic is also accumulated in jarosite beudantite solid solutions up to 8 4 wt as which occur as inclusions in the amorphous fe sulfoarsenates in efflorescent crusts on the surface of the waste pile as co precipitates with the fe iii sulfates copiapite 0 27 wt as and rhomboclase 0 87 wt as zinc and cu are incorporated primarily into fe ii sulfates i e melanterite in the interior of the waste pile and rozenite in the efflorescent crust the zn mineral dietrichite is also formed at the surface of the waste pile as a result of evaporation of pore solutions and is the only fe ii sulfate containing detectable amounts of as 0 64 wt lead is mainly co precipitated with minerals of the jarosite group where the pb content may reach 4 3 wt co precipitation of toxic elements with sulfates and sulfoarsenates of fe is shown to be a significant mechanism in controlling the concentration of heavy metals in pore solutions of high sulfide mine wastes precipitation of secondary phases causes the formation of a hardpan layer with low permeability at a depth of 1 1 5 m below the surface of the waste pile rainwater accumulates above the hardpan horizons and slowly drains along these aquicludes to the bottom of the pile most of the rainwater evaporates during infiltration this leads to formation of the described efflorescent sulfate crusts dissolution of these crusts during the next rain storm produces highly acidic surface waters ph 1 1 rich in so42 30 g l fe 18 g l as 0 24 g l zn 0 12 g l cu 0 04 g l pb and cd 0 002 g l during the warm t 0 c period of the year which lasts about 7 months these surface waters transport a total of a few tens of kilograms of as and zn several kilograms of cu and a few hundred grams of pb and cd from the waste pile into the mokry berikul river as a result the concentrations of these metals in the river water increase by an order of magnitude thus reaching levels close to or exceeding the maximum values permissible for drinking water

tomography of the western united states from regional arrival times first arrival times from regional distances 200 1200 km in the western united states extracted from the international seismological centre isc data set were inverted in a tomographic study to map the laterally varying pn velocity structure of the uppermost mantle i e the mantle lid and to estimate the crustal static delay at each seismograph station synthetic data were used to evaluate resolution results correlate well with major tectonic features we find low uppermost mantle velocities v 7 9 km s these low apparent pn velocities are primarily due to the effects of isostasy hotspot volcanism and crustal extension we interpret the low apparent pn velocities beneath the sierra nevada 7 6 7 7 km s to be the result of time delays introduced by ray paths tunneling through the deep crustal root the yellowstone hotspot migrating along the snake river plain has left low velocity 7 6 7 8 km s hot upper mantle in its wake lower pn velocities 7 8 km s beneath the extensional basin and range are also presumably due to hotter uppermost mantle based on station static delays for the basin and range we infer that moho depths there do not vary significantly from 30 km normal continental pn velocities 8 0 km s as well as thicker crust 40 50 km underlying the rocky mountains wyoming basin province colorado plateau and the northern columbia plateau indicate the presence of relatively cool uppermost mantle beneath these regions

hydrochemistry of superficial waters in the adoria mine area northern portugal environmental implications the purpose of this work is to characterize the hydrochemical behavior of acid mine drainages amd and superficial waters from the adoria mine area northern portugal samples of superficial and mine drainage water were collected for one year bi monthly with ph temperature eh conductivity and hco3 determined in situ with chemical analyses of so4 ca k mg na cl ag as bi co cu fe mn ni pb zn and cd in the mine there are acidic waters with low ph and significant concentrations of so4 and metals fe mn zn cu pb cd and ni while in the superficial natural stream waters outside the mine the ph is close to neutral with low conductivity and lower metal concentrations the stream waters inside the mine influence are intermediate in composition between amd and natural stream waters outside the mine influence principal component analysis pca shows a clear separation between amd galleries and amd tailings with tailings having a greater level of contamination

the moho in the northern basin and range province nevada along the cocorp 40 n seismic reflection transect cocorp seismic reflection profiles across nevada at about 40 n image a prominent essentially continuous band of reflectors at a two way traveltime of 9 to 11 s the approximate correspondence of this reflection time with estimates of the two way traveltime to the moho in this area provided by seismic refraction data suggests that the prominent reflections are from the moho the relief on these reflectors the reflection moho beneath nevada across a latitudinal transect of

birps deep seismic reflection studies of the british caledonides the western isles north channel winch traverse fig 1 an extension of the successful moist profile1 was recorded in 1982 at sea along the west coast of britain for birps british institutions reflection profiling syndicate by the geophysical company of norway geco the purpose of the winch traverse was to study crustal structure of the caledonian foreland to cross the caledonian orogen and to establish the three dimensional geometry of mantle reflectors originally seen on moist we describe here the data first emphasizing british caledonian structures and then discussing features of the deep crust of wider significance the data are of very good quality and contain clear moho and upper mantle reflections the lower crust is surprisingly reflective deeply penetrative thrusts are observed and there is firm evidence that several of the mesozoic basins round the shores of the united kingdom were formed by reactivation of older features

through thick and thin a new model for the colorado plateau from seismic refraction data from pacific to arizona crustal experiment we have constructed a model for the crust and uppermost mantle beneath the colorado plateau by combining newly acquired seismic refraction wide angle reflection data from the 1989 pacific to arizona crustal experiment pace cross profile with data collected by roller 1965 a combination of forward modeling methods was used to model travel times and relative amplitudes of crustal and upper mantle phases the salient features of the model for the colorado plateau hereafter referred to as the plateau are 1 an upper crust having an average velocity of 6 1 km s with a low vertical velocity gradient 2 midcrustal discontinuities at depths of 30 to 38 km beneath the plateau 3 a lower crust that varies in thickness 5 to 16 km and has an average velocity of 6 8 km s 4 a transitional lower crust upper mantle boundary and 5 a crustal thickness of 45 3 km a comparison of our new model for the colorado plateau with recent models for the basin and range shows that the upper crusts of the two provinces are similar but that the lower crust of the plateau is thicker particularly in the plateau s central region these observations are consistent with the idea that the basin and range could have formed from crust like that of the colorado plateau

seismic profiling the continental lithosphere deep seismic reflection profiling is successfully being used worldwide to study the structure of the continental crust1 7 the moist8 profile recorded by birps british institutions reflection profiling syndicate was the first to show that the structure of the upper mantle could also be imaged given a powerful source and long recording times birps has recently acquired an ultra deep seismic reflection line drum deep reflections from the upper mantle the drum line was designed specifically to investigate the reflectivity of the lower continental lithosphere and was therefore recorded to a two way time twt of 30 s giving a depth of penetration into the lithosphere of 110 km this profile has now revealed strong reflections which are unequivocally from the lower lithosphere well below the base of the crust and which are as far as we are aware the deepest and most continuous structures imaged in the upper mantle by multi channel seismic reflection profiling

mapping high pn velocity beneath the colorado plateau constrains uplift models the massive international seismological centre data set of the past 20 years and the two station method are used to determine pn velocities in the mantle lid beneath the colorado plateau in this method the event is located at distances where pn is the first arrival 2 16 and the path is in or very near the azimuth of the two station pair and crosses the plateau this technique to a large extent minimizes the hypocenter mislocation effect and possible errors due to variations in the crustal structure near the source since only the difference in travel times at the two stations is used however this technique has a few underlying assumptions and possible sources of errors such as the quality of the pn data base and station delays caused by varying crustal structure that require an extremely careful application of the method a detailed study of the source of errors and a methodology of selection of the data are presented application of this method to the colorado plateau using all possible two station pairs from 53 stations located within or along the margin of the plateau yields an average high pn velocity of 8 12 0 09 km s this value is considerably larger than the average value of 7 83 km s based on available but very limited seismic refraction profiles but is remarkably similar to the average value of 8 1 km s for the relatively stable midcontinent region our new pn velocity for the colorado plateau eliminates the paradox in the literature that emphasizes the rather close similarity between average pn velocities beneath the colorado plateau and the basin and range province while their tectonic and magmatic cenozoic history is dramatically different previous models for the structure and evolution of the plateau have used the low pn velocity as an important constraint on density and thermal state of the lithosphere hence such models should be reexamined on the basis of this new uppermost mantle pn velocity determination there are two main models that have been proposed to explain the 2 km uplift of the colorado plateau one is based on a combination of thermal thinning of the lithosphere and crustal thickening and the other involves a combination of the delamination of the subducted subhorizontal farallon oceanic plate from the overriding north american plate and crustal thickening we show that the delamination model is more readily consistent not only with our velocity determination and the elevation of the plateau but also with varied geological observations reported in the literature that concern the cenozoic evolution of western north america

deep seismic reflection characteristics of the continental crust four types of seismic reflection fabrics appear to characterize the continental crust 1 a cratonic fabric dominated by diffractions and dipping reflections but lacking a pronounced reflection moho 2 regions of thin skinned foreland deformation with abundant shallow but sparse deep reflections 3 a unidirectional fabric that dips toward the hinterland and may represent a crustal scale ramp zone and 4 zones of highly layered lower crust and high amplitude reflection moho the first three types are commonly observed in transects across single mountain belts but the fourth appears to correspond to regions of elevated lower crustal temperatures such as those encountered in rift provinces and perhaps elsewhere

laramide crustal thickening event in the rocky mountain foreland and great plains the rocky mountain foreland and great plains of the western united states were formerly part of a continental platform adjusted by erosion and deposition in cambrian through jurassic time to near mean sea level and therefore to a near uniform crustal thickness of approximately 33 km today the region stands at regional elevations up to 2 km isostatically supported by a crust exceeding 50 km in thickness reasonable estimates of tertiary sedimentation and laramide strain do not account for more than 15 of the implied thickening however from approximately 70 40 m y b p this region was underlain by a horizontally subducting slab of farallon plate lithosphere moving northeast this slab could have been the cause of the thickening finite difference thermal models with specified kinematics show only a temporary cooling of the base of the north american lithosphere by this slab the excess weight of the slab would have depressed the region plate bending calculations show a quantitative agreement of predicted depression with upper cretaceous isopachs since depression by this slab lasted until the eocene at least the latest cretaceous regression was probably caused by a laramide crustal thickening event the farallon slab might have caused crustal thickening in two ways its excess weight would have drawn in ductile lower crust from surrounding regions however calculations show that this effect is too slow too local and too reversible to explain most of the crustal thickening therefore it seems likely that ductile lower crust was transported from sw to ne by shear stresses which the farallon plate exerted on the base of the north american lithosphere a preliminary finite element calculation based on this hypothesis shows the correct general pattern of crustal thickening an unexpected but encouraging result is that predicted principal compression directions are orthogonal to many laramide basement uplifts

on the use of advection correction in trajectory calculations abstractan advection correction procedure is used to mitigate temporal interpolation errors in trajectory analyses constructed from gridded in space and time velocity data the procedure is based on a technique introduced by gal chen to reduce radar data analysis errors arising for the nonsimultaneity of the data collection experiments are conducted using data from a high resolution cloud model 1 cm1 numerical model simulation of a supercell storm initialized within an environment representative of the 24 may 2011 el reno oklahoma tornadic supercell storm trajectory analyses using advection correction are compared to traditional trajectory analyses using linear time interpolation backward trajectories are integrated over a 5 min period for a range of data input time intervals and for velocity pattern translation estimates obtained from different analysis subdomain sizes box widths and first guess options the use of advection correction reduces trajectory end point position errors for a large m

tectonics of mid tertiary extension along a transect through west central arizona large magnitude miocene extension in west central arizona occurred primarily along three imbricate northeast dipping normal faults the structurally highest of these faults the gently dipping buckskin rawhide detachment fault accommodated approximately 66 km of crustal extension whereas the two structurally lower faults accommodated a total of about 20 km extension due to this large magnitude extension an area at the earth s surface that was 10 to 20 km wide is now over a 100 km wide and crystalline rocks with mid tertiary mylonitic fabrics uncovered by detachment faulting are exposed over roughly 2000 km in the harcuvar metamorphic core complex most of the upper plate of the buckskin rawhide detachment fault was largely undeformed by internal extension only the thin tapered end of the upper plate was highly extended during extension the lower plate must have flexed to conform to the listric underside of the upper plate and to have flattened to its present subhorizontal form as it was uncovered grooves on the underside of the upper plate were apparently imposed on the pliable lower plate as it was denuded forming extension parallel folds in the lower plate low flexural strength characterized the lower plate during denudation and a highly mobile low viscosity deeper crust must have effectively decoupled the upper crust from the mantle lithosphere

poisson s ratios of the upper and lower crust and the sub moho mantle beneath central honshu japan abstract poisson s ratios of the upper and lower crust and the sub moho mantle beneath central honshu japan are investigated using three independent methods that are based on s to p ratios of apparent velocities the wadati diagrams and an inversion of p and s arrivals shallow earthquakes at distances of 200 500 km from the nagoya university telemeter network are used for the apparent velocity ratio method crustal and subcrustal earth quakes under the network are used for the other two methods the network consists of wide band seismometers with three components which are particularly suitable for detecting s waves the three different methods give a consistent result for poisson s ratio that is 1 0 23 0 01 in the upper crust 2 0 26 0 28 in both the lower crust and in the sub moho mantle the result indicates a sharp contrast in between the upper and the lower crust rather than at the moho the low in the upper crust can only be explained by the presence of a substantial amount of free quartz indicating granitic rocks a higher in the lower crust suggests that this portion is presumably less saturated in silica and may be even undersaturated pointing to intermediate to mafic rocks the sub moho is almost equal to the averaged over the entire upper mantle that has been estimated from the wadati diagrams of deep shocks beneath japan but is higher than those calculated from pn and sn velocities in oceanic and stable continental regions

paleolithospheric structure revealed by continental geoid anomalies abstract lithospheric geoid anomalies record changes in elevation and potential energy experienced by continental lithosphere estimates of local isostatic equilibration and potential energy in tandem with lithosphere related geoid anomalies can be used to estimate paleolithospheric thickness providing a clearer understanding of how and why continental topography is developed we employ several simplifying assumptions about the crustal and mantle lithosphere density and structure and readily acknowledge that our results are therefore first order approximations to predict the pre orogenic structure of the lithosphere at the outset we emphasize that while this approach does not provide an exhaustive evaluation of the deformation mechanism it does serve to quantify the relative role played by the variations in the crustal and upper mantle components of the lithosphere in this way we are able to use independent measurement of lithospheric geoid anomalies current post orogenic elevation and lithospheric structure and paleoelevation information to estimate topographic development and structural support over time application of this technique to the southwestern united states indicates that the uplift of the colorado plateau is the result of processes in both the crust and mantle lithosphere and that the lithosphere of the pre orogenic southern basin and range was thinned relative to the northern basin and range and colorado plateau although we use the southwestern u s as an example this method can help constrain uplift mechanisms for any region for which the structure and geoid anomaly of the modern lithosphere is well understood