multi taxa isotopic investigation of paleohydrology in the lower cretaceous cedar mountain formation eastern utah u s a deciphering effects of the nevadaplano plateau on regional climate we investigate the regional climatic effects of the formation of the nevadaplano plateau during the sevier orogeny in an overall warming world paleohydrology was reconstructed from 590 individual measurements of phosphate o isotopes in continental faunas of the lower cretaceous cedar mountain formation utah u s a semi aquatic turtles crocodiles and terrestrial dinosaurs taxa are compared to coeval pedogenic carbonates to interpret changing water sources over time samples were grouped into four stratigraphic faunas lower yellow cat upper yellow cat ruby ranch and mussentuchit members resulting isotopic values were converted to d18 ow values using established d 18 op d 18 ow and d 18 oc d 18 ow relationships at a formation scale turtles d 18 op 14 1 to 15 7 v smow and crocodiles d 18 op 15 0 to 19 2 document water compositions of 28 1 to 26 1 and 27 7 to 24 2 respectively within the zonal range for formation scale meteoric water at 34u n paleolatitude 27 1 to 24 8 established by pedogenic carbonates d18 oc 22 0 to 23 5 v smow these data suggest that like soil carbonates turtle and crocodile phosphate isotopes can be used as proxies for meteoric water isotopic composition dinosaurd18 op sauropods 19 7 to 21 9 ornithischians 16 6to 21 7 small theropods 16 9to 18 2 andlarge allosauroids 19 1 to 20 3 values generally exceed those of semi aquatic taxa using mass balance equations for modern terrestrial animals adjusted for size and inferred dinosaur physiology ingested water is calculated for the above dinosaur groups on a member scale when meteoric water values are compared with calculated dinosaur drinking water values are equal to or lighter than meteoric water for most herbivorous groups as low as 215 5 for ornithischians and equal to or heavier than meteoric water for most carnivorous groups as high as 22 0 for allosauroids changes in d18 ometeoric water d 18 odinosaur ingested water faunal assemblages and sedimentology from member to member correlate to thrusting events of the sevier orogeny high elevations in the orogeny attenuated the influences of pacific moisture causing rainshadow induced aridity on the leeward foreland basin during upper yellow cat time and hosted seasonal snow accumulation by the end of ruby ranch time as suggested by 18 o enriched water e g up to an average of 22 0 from an allosauroid tooth and extremely 18 o depleted water e g 215 5 for ornithischians in the ruby ranch member by mussentuchit time delivery of the western interior seaway dominated moisture to the region despite continued rise of the sevier mountains

large scale dynamics of the mesosphere and lower thermosphere an analysis using the extended canadian middle atmosphere model the extended canadian middle atmosphere model is used to investigate the large scale dynamics of the mesosphere and lower thermosphere mlt it is shown that the 4 day wave is substantially amplified in southern polar winter in the presence of instabilities arising from strong vertical shears in the mlt zonal mean zonal winds brought about by parameterized nonorographic gravity wave drag a weaker 4 day wave in northern polar winter is attributed to the weaker wind shears that result from weaker parameterized wave drag the 2 day wave also exhibits a strong dependence on zonal wind shears in agreement with previous modeling studies in the equatorial upper mesosphere the migrating diurnal tide provides most of the resolved westward wave forcing which varies semiannually in conjunction with the tide itself resolved forcing by eastward traveling disturbances is dominated by smaller scales nonmigrating tides and other planetary scale waves play only a minor role in the zonal mean zonal momentum budget in the tropics at these heights resolved waves are shown to play a significant role in the zonal mean meridional momentum budget in the mlt impacting significantly on gradient wind balance balance fails at low latitudes as a result of a strong reynolds stress associated with the migrating diurnal tide an effect which is most pronounced at equinox when the tide is strongest resolved and parameterized waves account for most of the imbalance at higher latitudes in summer this results in the gradient wind underestimating the actual eastward wind reversal by up to 40

a model for attenuation of backscatter due to sediment accumulations and its application to determine sediment thicknesses with gloria sidescan sonar where the seafloor consists of a highly backscattering surface covered with a drape of fine grained sediment and where the sediment does not contribute significantly to the backscattered signal the sediment thickness can potentially be inferred from the amount of signal attenuation in the sediment layer a first order acoustical model is proposed in which the signal strength is reduced by an amount proportional to the sediment thickness and attenuation rate in the sediments data collected with geological long range inclined azdic gloria are used to develop and test this model at an acoustic frequency of 6 5 khz the range of sediment thickness that the sonar can potentially recover is 0 20 m a range that is often below the resolution of vertical profilers in the first example the signal variation with grazing angle over a uniformly buried surface is analyzed for attenuation which is expected to increase toward shallow grazing angles and longer attenuating paths through the sediment layer the surface is a lava flow north of hawaii covered by 1 2 m of fine grained sediments clague et al 1990 and gloria data analyzed with the model suggest an attenuation coefficient of 0 2 0 4 db m a value consistent with results from laboratory and field measurements of sediment attenuation in the second example a rocky surface is buried by varying amounts of sediment which is analyzed at almost constant grazing angle the surface is the volcanic basement of the southeast indian ridge and gloria data reveal the thickening of the sediment cover with distance away from the spreading center this is used to derive an average sedimentation rate of 6 mm ka which is generally consistent with results from other studies and suggests that this technique may be used to study differences in sedimentation rates between different regions furthermore the model is used to calculate from image amplitude distributions the sediment thickness distribution which represents the accumulation of sediments in ponds and the exposure of abyssal hills these sedimentary processes are also reflected in the standard deviation of sediment thickness which increases with seafloor age i explore the various sources of error in estimating sediment thickness using this technique and propose a model for nonuniform sediment drapes the first order model assumes a uniform thickness at the subfootprint scale

an estimate of the momentum deposition in the lower thermosphere by the observed diurnal tide abstract this paper reports a calculation of the acceleration of the zonal mean flow induced by dissipating tides in the equatorial lower thermosphere estimates of the gravest symmetric gravitational hough mode 1 1 of the migrating diurnal tide are obtained from monthly composites of global winds observed by the upper atmosphere research satellite high resolution doppler imager using the principles of classical tidal theory the tidal momentum flux divergence is computed for a series of monthly mean 1 1 fields from january 1992 to may 1993 the contribution to the mean flow by the leading mode of the migrating tide ranges between 5 and 20 easterly m s 1 day 1 in the equatorial lower thermosphere a semiannual variation is noted in the tidal amplitudes and the inferred tidal accelerations these variations are consistent with observed trends in the zonal mean flow of the lower thermosphere

short period fluctuations of the diurnal tide observed with low latitude mf and meteor radars during cadre evidence for gravity wave tidal interactions mf and meteor radar data from four equatorial and subtropical sites hawaii christmas island jakarta and adelaide are used to examine diurnal tide amplitude and phase variability at mesosphere and lower thermosphere altitudes all sites exhibit significant seasonal variability with the largest amplitude fluctuations occurring at hawaii and adelaide shorter term variability is found to occur primarily on timescales of 5 to 30 days amplitude and phase fluctuations are well correlated among different sites on occasion but in general the amplitude and phase coherences are low and suggest significant local influences on the tidal structures the temporal behavior of height variations of the diurnal tide amplitude and phase is also examined cross correlations and cross spectra of these tidal parameters especially between the amplitude and phase are examined closely the tendency for phase maxima to lead amplitude maxima is consistent with tidal modulation of gravity wave propagation and momentum fluxes with a corresponding feedback by the gravity wave momentum flux divergences on the observed tidal structures these results substantially extend previous more limited studies of gravity wave tidal interactions and provide a statistical basis for the possible importance of this interaction and its influences on the diurnal tidal structure

empirical model of 90 120 km horizontal winds from wind imaging interferometer green line measurements in 1992 1993 an empirical model of horizontal winds is developed based on wind imaging interferometer windii green line observations between 90 and 120 km in 1992 1993 the model includes mean winds solar diurnal and semidiurnal tides and some planetary wave components as well as annual and semiannual variations in these fields its formulation is similar to that of hwm 90 and hwm 93 of hedin et al 1991 1996 but greatly modified and extended to use the higher resolution global wind measurements now available from windii while the technique will only reach fruition when results can be combined from the wind measurements of several years by the different instruments on the uars satellite this interim but updated model provides improved representation of the temporal and geographic variations of the wind fields compared to the current reference models the model generated climatological mean wind diurnal tides and some samples of the entire wind motion fields are presented and compared with the windii measurements and analysis results obtained from the data sets by different methods to check the consistencies between the model representations and the observations this study also reveals a dual cell structure in the meridional component of the diurnal tides with two amplitude maxima centered around 95 and 102 km near 20 latitude and strongly symmetric about the equator at equinox large interannual variabilities are found to exist in both diurnal wind components with maximum amplitudes of 40 and 55 m s for the zonal and meridional respectively at the vernal equinox of 1992

intraplate extensional tectonics of the eastern basin range inferences on structural style from seismic reflection data regional tectonics and thermal mechanical models of brittle ductile deformation the general lack of a correlation between earthquakes and surface faulting in the interior of the western u s cordillera has motivated our efforts to evaluate the geometry structural style and mechanism of normal faulting characteristic of this region of intraplate extension to address the problem we have interpreted over 1500 km of seismic reflection data and constructed detailed cross sections of the upper crust rheological models of the continental crust were calculated to examine the possibility of shallow quasi plastic flow and its influence on faulting in the eastern basin range the western colorado plateau and the middle rocky mountains our data and interpretations have revealed the following styles of cenozoic deformation 1 steep to low angle dip normal faulting along the wasatch fault 2 low angle dip and listric normal faulting possibly associated with movement on preexisting thrusts 3 the occurrence of asymmetric mostly eastward tilted tertiary basins that are bounded by low to moderate dipping planar and listric faults and 4 at least three vertically stacked en echelon low angle reflections in the mid to upper crust that dip gently westward from 3 km beneath the wasatch plateau to over 15 km at the utah nevada border these reflections are interpreted as normal detachment faults the structural style of the pervasive low to moderate angle dipping faults cannot be easily reconciled with classic brittle failure theory but the interpreted termination of normal faults at or above the deeper low angle reflections suggests the presence of shallow zones of ductile deformation that may have accommodated slip an important observation based on interpretations of seismic reflection profiles is that normal fault zones dip more gently in the subsurface than their associated scarps in unconsolidated surficial deposits segment boundaries of the wasatch fault zone apparently coincide with the positions of east trending displacement transfer structures in thrust sheets and the position of the precambrian uinta aulacogen suggesting that preexisting crustal structure partly controls the geometry of extension to examine the influence of ductile deformation quasi plastic flow was modeled for appropriate geotherms of the basin range and colorado plateau crusts these models provide constraints on the depth to the frictional quasi plastic transition that occurs as shallow as 8 km in the eastern basin range this depth also corresponds to the approximate depth above which most accurately determined earthquake foci for small earthquakes m 5 5 appear to nucleate at 10 15 km in or near the brittle ductile transition the rheological modeling suggests that a thermally deforming continental lithosphere plays an important role in the evolution of this extending intraplate region large scale low angle reflections may represent decollements and normal faults at the top of upper crustal zones of reduced shearing strength and higher ductility

eliassen palm fluxes of the 2 day wave abstract high resolution doppler imager hrdi winds and temperatures are used to diagnose a 2 day wave event detected in the southern hemisphere during january 1994 a novel aspect of this study is the focus upon the wave fluxes throughout the 65 100 km range and their relationship to the background state a wave packet composed of zonal wavenumbers 2 3 and 4 propagates westward with a phase speed near 60 m s 1 the periods associated with zonal wavenumbers 2 3 and 4 are 3 5 2 1 and 1 7 days respectively the morphology of the 2 day temperature and wind fields is consistent with that of a developing baroclinic wave the divergence of the eliassen palm flux of zonal wavenumbers 2 4 is dominated by the vertical convergence of meridional heat flux the wave driving or eliassen palm flux divergence per unit mass is predominantly westward with magnitudes on the order of 5 m s 1 day 1 a steady state quasigeostrophic model of the mean meridionai circulation is used to estimate the mean wind respon

late cretaceous paleocene synorogenic sedimentation and kinematic history of the sevier thrust belt northeast utah and southwest wyoming integration of cross cutting structural relationships overlapping sedimentary units new conglomerate provenance data and radiometric and palynological dates provides a basis for reinterpretation of the distribution and timing of late cretaceous through paleocene thrust faulting in the northeast utah southwest wyoming part of the sevier thrust belt these data indicate a general eastward progression of deformation that was punctuated by local out of sequence and hinterlandward verging events provenance data delimit a sequential restoration of a regional cross section the principal thrust systems in northeast utah and southwest wyoming are the willard ogden crawford absaroka and hogsback thrusts the willard is the westernmost structurally highest and oldest of the thrusts it carries a unique section of thick proterozoic sedimentary rocks as well as paleozoic rocks and was folded during displacement on younger thrust systems the next youngest thrust system is the ogden which comprises several basement rooted imbricate thrusts that together form a large antiformal stack with a structural culmination in the wasatch range growth of the wasatch culmination took place during coniacian through paleocene time contemporaneous with sequential displacement on the frontal crawford absaroka and hogsback thrusts total shortening in this part of the thrust belt was 100 km and structural relief of 25 km developed in the area of the wasatch culmination during coniacian through paleocene time thrusting followed an overall eastward progression that was interrupted by local out of sequence and hinterlandward verging events several episodes of synchronous displacement on two or more thrusts can be demonstrated shortening occurred in three main episodes the first episode 89 84 ma involved 33 km of shortening on the crawford thrust and its footwall imbricates approximately 19 km of structural relief on the basement cover contact developed in the area of the wasatch culmination the second episode 84 62 ma with a break between 75 69 ma involved 30 km of shortening mainly on the absaroka thrust and development of an additional 6 km of structural relief in the culmination the third episode of shortening 56 50 ma took place on the hogsback thrust involved 21 km of horizontal shortening and produced no significant increase in structural relief in the culmination long term rates of shortening ranged between 3 0 mm yr and 6 6 mm yr these three episodes of shortening produced three large accumulations of synorogenic conglomerate totaling 3 km in thickness the henefer formation and echo canyon and weber canyon conglomerates were deposited during crawford thrusting the evanston formation was deposited during and after absaroka thrusting and the lower conglomeratic part of the wasatch formation was deposited during and after hogsback thrusting most of the sediment in these synorogenic units however was derived from repeated uplift of the willard thrust sheet and from the eastern flank of the wasatch culmination in the rear part of the thrust belt only local minor accumulations were derived from the frontal ramp anticlines sediment accumulation and structural deformation were generally out of phase periods of regional shortening and uplift were marked by development of unconformities and sediment bypassing to distal parts of the foreland basin periods of structural inactivity were marked by accumulation of aerially widespread braided river conglomerate on top of the thrust belt one exception to this pattern is the henefer echo canyon weber canyon conglomerate deposit which contains evidence of progressive deformation in close proximity to the tip of the crawford thrust comparison of the sequential restoration with the late cretaceous subsidence history and isopach patterns in the distal foreland basin of western wyoming demonstrates that the principal controls on regional subsidence and sediment supply were the growth and erosion of the wasatch culmination growth of the duplex beneath the culmination may have been a means of maintaining critical taper in the thrust wedge

structural evolution of connecting splay duplexes and their implications for critical taper an example based on geometry and kinematics of the canyon range culmination sevier belt central utah abstract critical taper in an evolving orogenic wedge can be maintained by structural thickening in the back of the wedge this is often achieved by folding and uplift of pre existing large internal thrust sheets by the continued growth and or reactivation of duplexes in the hinterland the growth of a blind imbricate complex off a lower thrust provides another mechanism for folding a higher thrust individual splays in a blind imbricate complex may have fault propagation folds and or fault bend folds associated with them if the splays reach the overlying thrust they serve as connecting splays between the lower thrust floor and the upper thrust roof thereby forming a connecting splay duplex csd this type of duplex geometry requires periodic reactivation of the pre existing roof thrust the canyon range thrust in central utah is an internal thrust that is folded into an overturned antiform synform pair and overrides its own synorogenic conglomerates the same conglomerates are infolded into the core of the synform and preserve critical timing information regarding the history of folding and thrust reactivation the folding is caused by the development of a footwall antiformal stack in the core of the canyon range antiformal culmination the geometry and timing relationships suggest that the structure grew as a csd regional timing relationships suggest that the growth of the csd and reactivation of the thrust took place during the later part of the evolution of the orogenic wedge and may have helped the wedge maintain critical taper during thrusting in the external fold and thrust belt

long term variability of mean winds in the mesosphere and lower thermosphere at low latitudes 1 long term variations of monthly mean zonal and meridional winds in the mesosphere and lower thermosphere mlt at low latitudes are analyzed using four medium frequency mf radars and three meteor radars located in the asia oceania region radar data taken at close by latitudes are appended to construct long term data sets with this we have long term data from five distinct latitudes within 22 viz 22 n 9 n 0 2 n 6 7 s and 21 s the data length varies at different latitudes and spans a maximum of two decades during 1990 2010 the zonal winds show semiannual oscillation sao at all locations with westward eastward winds during equinoxes solstices the month height pattern of sao is similar within 9 and is different at 22 the westward winds in the march equinox were enhanced every two or three years during 1990 2002 we define this phenomenon as mesospheric quasi biennial enhancement mqbe such signature is not clear after 2002 the meridional winds show annual oscillation ao with northward and southward winds during the december and june solstices respectively however the timing at which the wind direction changes does not coincide at all latitudes the amplitude of the ao is enhanced after 2004 and 2008 at 9 n and 7 s respectively orthogonal components of sao and ao are detected with persistent phase relation which suggests that the zonal and meridional winds are coupled the meridional winds show long term trends at latitudes of 9 n and 6 7 s but not at other latitudes the zonal winds do not show significant long term trends

proterozoic multistage ca 1 1 and 0 8 ga extension recorded in the grand canyon supergroup and establishment of northwest and north trending tectonic grains in the southwestern united states the grand canyon supergroup records at least two distinct periods of intracratonic extension and sedimentation in the late mesoproterozoic and neoproterozoic new 40 ar 39 ar age determinations indicate that the mesoproterozoic unkar group was deposited between ca 1 2 and 1 1 ga basins in which the unkar group was deposited and the related northwest striking faults were created by northeast southwest extension which was contemporaneous with regional northwest southeast grenville contraction new u pb data indicate that the neoproterozoic chuar group was deposited between 800 and 742 ma sedimentary and tectonic studies show that chuar deposition took place during east west extension and resulting normal slip across the butte fault this event is interpreted to be an intracratonic response to the breakup of rodinia and initiation of the cordilleran rift margin laramide monoclines of the grand canyon region have north and northwest trends reactivate faults that originated at the time of unkar and chuar deposition and can be traced for great distances hundreds of kilometers from the grand canyon we use the distribution of monoclines in the southwest to infer the extent of proterozoic extensional fault systems the 1 1 ga northwest trending structures and ca 800 700 ma north trending extensional structures created regional fault networks that were tectonically inverted during formation of the ancestral rocky mountains and laramide contraction and reactivated during tertiary extension

intraseasonal variability of high resolution doppler imager winds in the equatorial mesosphere and lower thermosphere analyses of high resolution doppler imager hrdi daytime equatorial zonal winds indicate significant variability on time scales of 20 121 days these appear as transient oscillations in the equatorial zonal mean zonal wind between 70 and 100 km the oscillations are characterized by two maxima near 75 and 95 km that are out of phase separated by a minimum near 80 km these features move downward in time and exhibit equatorial symmetry with maximum values at the equator during 1994 maximum amplitudes of the intraseasonal oscillation are 20 m s 1 in january and 30 m s 1 in june the intraseasonal variability present in hrdi winds is qualitatively consistent with variations on similar timescales reported at christmas island it has been hypothesized that the wind patterns at christmas island result from modulated gravity wave driving eckermann et al 1997 the results of the present study strongly support this view

the 1997 eruption of okmok volcano alaska a synthesis of remotely sensed imagery abstract okmok volcano in the eastern aleutian islands erupted in february and march of 1997 producing a 6 km long lava flow and low level ash plumes this caldera is one of the most active in the aleutian arc and is now the focus of international multidisciplinary studies a synthesis of remotely sensed data airsar derived dems landsat mss and etm data avhrr ers jers radarsat has given a sequence of events for the virtually unobserved 1997 eruption elevation data from the airsar sensor acquired in october 2000 over okmok were used to create a 5 m resolution dem mosaic of okmok volcano avhrr nighttime imagery has been analyzed between february 13 and april 11 1997 landsat imagery and sar data recorded prior to and after the eruption allowed us to accurately determine the extent of the new flow the flow was first observed on february 13 without precursory thermal anomalies at this time the flow was a large single lobe flowing north according to avhrr band 3 and 4 radiance data and ground observations the first lobe continued growing until mid to late march while a second smaller lobe began to form sometime between march 11 and 12 this is based on a jump in the thermal and volumetric flux determined from the imagery and the physical size of the thermal anomalies total radiance values waned after march 26 indicating lava effusion had ended and a cooling crust was growing the total area 8 9 km 2 thickness up to 50 m and volume 1 54 10 8 m 3 of the new lava flow were determined by combining observations from sar landsat etm and airsar dem data while the first lobe of the flow ponded in a pre eruption depression our data suggest the second lobe was volume limited remote sensing has become an integral part of the alaska volcano observatory s monitoring and hazard mitigation efforts studies like this allow access to remote volcanoes and provide methods to monitor potentially dangerous ones

structural configuration of the early cretaceous cordilleran foreland basin system and sevier thrust belt utah and colorado abstract stratigraphic and provenance data from lower cretaceous rocks in utah and colorado and structural evidence from the sevier belt in west central utah allow recognition of the ties between early thrust belt evolution and foreland basin system development regional isopach patterns of lower cretaceous strata define foreland basin system depozones lower cretaceous strata in west central utah that thicken westward from 100 m to 1 2 km were deposited within the flexurally subsiding foredeep depozone correlative units in eastern utah and western colorado 100 m thick were deposited in the back bulge depozone these thickness trends indicate the lower cretaceous foreland basin system consisted of a foredeep 100 180 km wide and forebulge 260 460 km wide a computer generated flexural model of the foreland basin system produces a reasonable match of the observed basin geometry using a 400 km wide l

case of the phantom foredeep early cretaceous in west central utah a reconstruction of the structure in west central utah shows that a major foredeep with sedimentary deposits possibly as thick as 6 km now eroded probably existed at the present site of the sevier desert during early cretaceous time and conceivably during late jurassic time concurrent emplacement and erosion of the canyon range thrust sheet provided the load and sediment much like the willard paris thrust sheet did for the better documented early cretaceous foredeep in northern utah and eastern idaho the onset of major thrusting in western utah may have been as early as callovian or as late as albian a 50 m y time span

direct observations of nonmigrating diurnal tides in the equatorial thermosphere 1 we present direct observations of nonmigrating diurnal tides in the 90 270 km range inferred from the upper atmosphere research satellite uars wind imaging interferometer windii a prominent zonal wavenumber 4 appears in daytime zonal winds extending to 180 km we interpret this signature as an eastward propagating diurnal wavenumber 3 de3 viewed from the satellite perspective this evidence of the extended upward propagation of de3 demonstrates that it acts as a direct coupling agent between the troposphere and the thermosphere and f region in addition to its role in the e region dynamo

meteor wind radar observations of gravity wave momentum fluxes and their forcing toward the mesospheric semiannual oscillation 1 wind measurements from continuous meteor radar observations during june 2004 may 2007 are used to estimate the gravity wave momentum fluxes in the mesosphere lower thermosphere mlt region over trivandrum 8 5 n 76 9 e a low latitude station in india the radial velocity variances in the 82 98 km height region which are mainly caused by gravity waves measured by the meteor radar are used to determine the gravity wave momentum fluxes using a novel method proposed by hocking 2005 altitude profiles of momentum fluxes of short period less than 2 3 h gravity waves are estimated for three continuous years seasonal variation in the gravity wave momentum fluxes showed semi annual variation with equinoctial maximum and solstitial minimum by using estimated gravity wave momentum fluxes an attempt is made to quantify their contribution in driving the mesospheric semi annual oscillation msao the mean flow acceleration estimated from the divergence of gravity wave momentum fluxes is compared with the observed mean flow acceleration computed from monthly mean zonal winds during six msao cycles over three years this comparison reveled that the gravity wave contribution toward the westerly phase of msao varies from 20 60 while that toward the easterly phase varies from 30 70 variations are observed from cycle to cycle in the gravity wave forcing toward both phases of msao the significance of the present study lies in estimating the gravity wave momentum fluxes in the mlt region and quantifying their contribution toward the generation of msao over the low latitude for the first time

diagenesis of a tight gas sand reservoir upper cretaceous mesaverde group piceance basin colorado abstract the upper cretaceous mesaverde group in the piceance basin western colorado contains thick sections of low porosity low permeability sandstones that are reservoirs for large accumulations of hydrocarbon gas the mesaverde sandstones are lithic arkoses and feldspathic litharenites containing quartz plagioclase variable k feldspar chert and volcanic rock fragments important diagenetic processes that have affected the sandstones include compaction dissolution of feldspar and or alteration to clay precipitation of carbonate and quartz cements precipitation of illite and alteration of detrital clays mixed layer illite smectite porosity is relatively constant a decrease in primary porosity downward is approximately balanced by an increase in secondary porosity with significant microporosity in authigenic and diagenetic clays k feldspar is almost completely absent below 5500 feet 1675 m fibrous illite is relatively abundant above this depth and variable in abundance below the k ar ages of the clays increase with depth from 40 m y at the top of the sampled section to 55 m y at the base indicating illitization of a precursor smectite at approximately the 100 c isotherm samples with abundant fibrous illite have relatively smaller age values mass balance calculations indicate that dissolution of k feldspar illitization of smectite and precipitation of fibrous illite were coupled these reactions suggest the transport of dissolved potassium upward hundreds of feet 100 300 m in the section possibly associated with water driven vertically by the migration of gas

global distribution and interannual variations of mesospheric and lower thermospheric neutral wind diurnal tide 1 migrating tide 1 using the timed doppler interferometer tidi mesospheric and lower thermospheric neutral wind multiyear data set 2002 2007 and ncar time general circulation models gcm 1 2 annual run results 2002 2005 at the tidi sampling points we study the migrating diurnal tide s global distribution interannual and seasonal variations in connection with the mean zonal wind interannual variations a strong quasi biennial oscillation qbo effect on the diurnal tide was observed in the tidi data and reproduced to a lesser degree in the time gcm run the migrating diurnal tide amplitude is larger during the eastward phase of the stratospheric qbo and weaker during the westward phase westward mesospheric equatorial mean zonal winds appeared during the eastward phase of the stratospheric qbo in 2002 2004 and 2006 the strongest qbo effect on both the migrating diurnal tide and mean zonal winds was observed during the march equinox the stronger tides may be related to the weaker gravity wave filtering in the stratosphere during the eastward phase stratospheric qbo the tidi data also exhibit large interhemispheric asymmetry the westward mean zonal winds in the mesosphere appeared to be associated with the enhanced diurnal tide the time gcm 1 2 diurnal tide amplitudes are in general smaller than those observed by the tidi instrument limited vertical spatial resolution for the time cgm 1 2 is suggested as the cause future improvements are expected with a higher spatial resolution in the model

tectonic control on the sequence stratigraphy of nonmarine retroarc foreland basin fills insights from the upper jurassic of central utah u s a abstract continental successions of the north american western interior retroarc foreland basin provide an excellent opportunity to evaluate the tectonic controls on nonmarine sequence stratigraphy the transition between the upper jurassic brushy basin member anastomosed fluvial system of the morrison formation and the gravelly braided river deposits of the buckhorn conglomerate has been studied to assess the dispersal of coarse clastics and the development of associated basin wide unconformities in a sequence stratigraphic framework the sharp contact between the two members is interpreted to be conformable based on stratigraphic sedimentologic and petrologic data collected at and near cedar mountain in central utah while a regional mature paleosol at the top of the buckhorn conglomerate indicates the presence of a major sequence boundary these interpretations are combined with paleoflow data and fluvial architectural analysis to reconstruct the evolution of the alluvial equilibrium profiles that controlled deposition of the succession the buckhorn conglomerate is interpreted as an example of a post orogenic deposit on the basis of 1 its tabular geometry 2 distance from the contemporaneous thrust belt 3 shift to transverse paleoflow direction from the preceding brushy basin axial drainage 4 conformable lower contact and 5 presence of an overlying sequence boundary with a westward expanding hiatus eroding the coeval foredeep the onset of a protracted period of low rate of orthogonal convergence between the farallon and north american plates resulted in tectonic quiescence and consequent isostatic rebound of the middle to late jurassic thrust belt and the contiguous contemporaneous foredeep as well as dynamic uplift the ensuing basin wide decrease in subsidence rate induced the progradation of the buckhorn alluvial plain into the morrison back bulge depozone and the subsequent generation of the overlying pedogenic unconformity which separates the deposits of the jurassic flexural event from the overlying sevier tectonostratigraphic unit

timing of deformation in overthrust belt and foreland of idaho wyoming and utah a review of the timing and displacement evidence of the major structures of the western wyoming overthrust belt and foreland shows there is a progression in thrust displacement apparent duration of motion and palinspastic position of thrust traces from west to east those toward the west moved farther for an apparently longer period of time and are more widely spaced in their restored positions than those toward the east however average thrust velocities are all on the order of 0 5 0 5 cm yr 0 2 in yr foreland events are in part synchronous with thrust belt events and had an effect on them although dating precision varies widely on major normal faults present evidence does not contradict the generally held view that all normal faults postdate the youngest thrusting

southwestward weakening of wyoming lithosphere during the laramide orogeny the mechanism of laramide deformation in the central rocky mountains remains enigmatic it is generally agreed that the deformation resulted from low angle subduction of the farallon plate beneath the north american plate during the latest cretaceous early eocene however recent studies have suggested the importance of slab removal or slab rollback in causing this deformation here we infer wyoming lithosphere structure and surface deformation pattern by conducting 2 d flexural subsidence modeling in order to provide constraints on the mechanism of laramide deformation we assume that wyoming lithosphere behaved as an infinite elastic plate subject to tectonic loading of mountain ranges and conduct 2 d flexural subsidence modeling to major laramide basins to document lithospheric stiffness and mountain load height our results show that the stiffness of wyoming lithosphere varied slightly in each basin during the 30 myr duration of the laramide deformation and decreased from northeastern wyoming te 32 46 km to southwestern wyoming te 6 9 km our results also imply that the increase of equivalent load height of major laramide ranges accelerated during the early eocene we propose that the bending stresses induced by the topographic load of the sevier fold and thrust belt combined with crust mantle decoupling initiated by the overthickened sevier hinterland and the end loads due to the low angle subduction at the western edge of the thick wyoming craton have caused the southwestward decrease of lithospheric stiffness in wyoming moreover we attribute the accelerated load height gain during the early eocene to both dynamic and isostatic effects associated with slab rollback

sequence stratigraphy of a condensed low accommodation succession lower upper cretaceous dakota sandstone henry mountains southeastern utah cretaceous low accommodation deposits have been extensively studied in the subsurface of the western interior of north america because of their prolific hydrocarbon production and remaining potential understanding the stratigraphic complexities of these deposits in the subsurface relies strongly on detailed outcrop analogs in this study the dakota sandstone was examined along 100 km 62 mi of semicontinuous outcrop between the towns of hanksville and ticaboo in the henry mountains of southeastern utah this region represented a low accommodation setting located over the forebulge of the cretaceous western interior basin during accumulation of the unit the dakota sandstone is 0 to 38 m 125 ft thick of cenomanian age and records multiple cycles of sediment accumulation the dakota sandstone is subdivided into two condensed top truncated stratigraphic sequences the upper of which contains two parasequences the basal parts of both sequences are composed of braided fluvial conglomerates and sandstone overlain by tidally influenced fluvial sandstone inclined heterolithically stratified estuarine mudstone carbonaceous shale and coal the overlying parasequences consist of coarsening upward lower to upper shoreface mudstone sandstone tidal inlet deposits and oyster shell concentrations these facies define tripartite subdivisions of depositional environments typical of wave dominated estuaries the fluvial deposits may represent lowstand deposits but overall sediments accumulated during transgressive systems tracts tst the parasequences recorded in the henry mountains are similar to the dakota sandstone of northwestern new mexico and to high frequency sequences identified in the kaiparowits plateau approximately 80 km 50 mi to the southwest which suggests eustatic driving mechanisms the best potential for hydrocarbon reservoirs occurs in fluvial sandstones and conglomerates

two new methods of paleocurrent determination from trough cross stratification abstract trough cross stratification is the most abundant accurate and efficient palcocurrent direction indicator in fluvial deposits however exposures in which trough axes can be measured are rare two new methods are presented for the determination of paleocurrent directions from the more common exposure types namely the use of three dimensional exposures of oblique cuts through individual trough limbs and two dimensional exposures of sets of trough cross strata three dimensional exposures of trough limbs can be measured and treated statistically on a stereographic plot to determine the average trough axis orientation in two dimensional exposures characteristic asymmetry of the basal scour surface and truncation of foreset laminae can aid in estimation within about 25 of pal ocurrent direction

foreland basin structural growth recorded in the turonian ferron sandstone of the western interior seaway basin usa tectonic forcing of stratigraphic architecture is likely in foreland basins tectonic driving forces are increasingly being invoked to explain stratigraphic patterns in the cretaceous western interior seaway basin of north america yet the evidence is largely circumstantial and the details of driving forces remain elusive in this paper i show direct stratigraphic evidence for syndepositional growth of a structural arch with at least 50 m of relief during accumulation of the upper turonian ferron sandstone in south central utah united states progressive growth of the arch was superimposed on several high frequency stratal cycles that were driven by a more regionally extensive process geodynamic or eustatic and that produced laterally amalgamated sandstone bodies in a depositional strike parallel orientation north south all of this stratigraphy was then truncated by a more or less planar erosion surface sequence boundary that can be traced physically over at least 67 km north south this surface was later tilted northward such that the upper member of the ferron sandstone thins progressively southward from 50 to 10 m over 67 km the facies juxtapositions revealed by the ferron sandstone could if seen in exposure of limited lateral extent be wrongly interpreted as recording regionally extensive relative sea level drops and potentially used in error as evidence for substantial eustatic sea level falls during the turonian the folding and tilting documented in this study can be clearly attributed to geodynamic and or tectonic driving forces likely related to migration of a forebulge

andean scale highlands in the late cretaceous cordillera of the north american western margin from the late jurassic through the cretaceous collision between the north american and farallon plates drove extensive thin skinned thrusting and crustal shortening that resulted in substantial relief in the north american cordillera the elevation history of this region is tightly linked to the tectonic climatic and landscape evolution of western north america but is not well constrained here we use an atmospheric general circulation model with integrated oxygen isotope tracers isocam3 to predict how isotope ratios of precipitation would change along the north american cordillera as the mean elevation of orogenic highlands increased from 1200 m to 3975 m with increases in mean elevation highland temperatures fall monsoonal circulation along the eastern front of the cordillera is enhanced and wet season generally spring and summer precipitation increases simulated oxygen isotopic ratios in that precipitation are compared to those obtained from geologic materials e g fossil bivalves authigenic minerals quantification of match between model and data derived 18o values suggests that during the late cretaceous the best approximation of regional paleoelevation in western north america is a large orogen on the scale of the modern andes mountains with a mean elevation approaching 4000 m and a north south extent of at least 15 of latitude

cenozoic and mesozoic structure of the eastern basin and range province utah from cocorp seismic reflection data cocorp seismic reflection data collected from the eastern basin and range in west central utah provide information on cenozoic extensional tectonics mesozoic thrusting and their interrelationships those data show a series of remarkably continuous low angle reflectors that extend more than 120 km perpendicular to strike and can be traced as deep as 15 20 km over that distance none of these events are significantly cut by any high angle normal faults a major detachment beneath the sevier desert can be traced from a surface zone of normal faulting to a depth of 12 15 km with a regional apparent westward dip of 12 tentative correlation of upper and lower plate events suggests 30 60 km of extensional displacement on this detachment whether this structure is a reactivated mesozoic thrust is uncertain west steepening splays off the end of the detachment reach depths of 20 km and may represent a major mesozoic ramp or zones of distributed ductile shearing during extension some events are interpreted to be mesozoic thrusts of which at least one beneath the house range has been reactivated during the cenozoic the snake range decollement dips gently east and has a sense of cenozoic displacement opposite to that of other cenozoic detachments farther east deep events are most numerous beneath the east side of the sevier desert where they occur to depths of 30 km at the top of or perhaps partly within the anomalously low velocity upper mantle

evolution of the northern cordilleran foreland basin during the middle cretaceous a detailed study of the middle late cenomanian belle fourche formation in southern alberta helps to elucidate the evolution of the cordilleran foreland basin during the middle cretaceous by combining isopach data from the study area with previously published research on middle cretaceous stratigraphy in adjacent areas of northern alberta and montana it is possible to defi ne the position of the proximal foredeep forebulge and backbulge depozones from late albian to cenomanian time the foredeep probably lay to the west of the present fold thrust belt in western montana from the late albian to middle cenomanian with the forebulge extending northwestward through the northwest corner of wyoming and curving northeastward through the present day location of calgary thick dunvegan deposits middle cenomanian of northwestern alberta are interpreted as foredeep deposits palinspastic reconstruction of the southern rocky mountains of alberta is consistent with a location of the foredeep within the area of the present fold thrust belt at the end of the middle cenomanian the forebulge retreated westward within alberta defi ning a nearly straight northwest southeast trend through the present position of the foothills and front ranges of alberta and northwestern montana the change in trend of the foreland basin at the end of the middle cenomanian may refl ect the change of convergence vectors along the western margin of north america during the middle cretaceous

radar polarization properties of volcanic and playa surfaces applications to terrestrial remote sensing and venus data interpretation the radar polarization properties of lava flows in hawaii kilauea and arizona sp flow and two play a surfaces lunar lake nevada and lavic lake california are compared to the predicted behaviors of theoretical scattering models at 5 7 cm and 24 cm wavelengths kilauea lava flows can be modeled by a combination of facet and diffuse dipole like scattering scattering by rock faces on the scale of the radar wavelength is proposed to account for much of the facet return the radar echoes at 24 cm wavelength from sp flow are on average consistent with entirely diffuse scattering but there are regions within the flow where circular polarization ratios exceed unity suggesting a coherent scattering effect 68 cm data for the lava flows show evidence of radar penetration and volume scattering the playa surfaces are characterized by polarization properties which in some cases are qualitatively consistent with the first order small perturbation model but the echoes do not closely match the predictions of this model for any reasonable dielectric constant value these results show that it may be difficult to construct invertible models for the polarization behavior of some surfaces the playas whereas for others the kilauea lava flows the scattering properties can be successfully modeled the first order small perturbation model is not appropriate for inverse modeling of most terrestrial lava flows though very smooth surfaces on venus may be amenable to the use of this model high circular polarization ratios observed for sp flow tentatively attributed here to coherent backscatter may be analogous to arecibo observations of high reflectivity areas on venus

extensional collapse along the sevier desert reflection northern sevier desert basin western united states newly released and previously published seismic reflection data from the northern sevier desert basin provide a complete seismic transect between the tilted western margin of the basin and the eastern breakaway zone when tied to well and surface age data the transect delineates a continuum of extensional fault and basin fill geometries that developed between late oligocene and pleistocene time across the basin a minimum of 18 km of top to the west normal displacement is estimated across the sevier desert from only the most conspicuous growth geometries and offsets across listric normal faults that sole downward into the sevier desert reflection sdr the sdr clearly marks a normal fault zone beneath the entire basin where stratal truncations are imaged for 50 of the 39 km length of the reflection east of the cricket mountains block restoration of extensional displacement along this entire 39 km fault length is necessary to reconstruct the pre oligocene configuration and erosion level of sevier thrust sheets across the sevier desert area the sdr normal fault zone underlies the former topographic crest of the sevier orogenic belt where it accommodated extensional collapse after cessation of regional contractile tectonism

thrust loads and foreland basin evolution cretaceous western united states two dimensional modeling of loading during the formation of the idaho wyoming thrust belt shows that regional isostatic compensation by flexure of an elastic lithosphere is sufficient to control the formation of a foreland basin the flexural rigidity of the lithosphere is inferred to have been approximately 1023 nm 1030 dyne cm on the basis of palinspastic comparison of predicted downwarping due to the thrust plate loads to the shape of the sedimentary wedge on the west side of the cretaceous western interior seaway erosion of part of the uplifted thrust plates redistributed the load depositing it farther to the east thereby causing subsidence over a much wider area than could have been accomplished only by the loading by thrust plates paleotopography after major cretaceous thrust events was calculated the resulting mountainous terrain gentle alluvial plain and flat sea floor correspond well with the topography of the modern foreland thrust belt and basin system in the andes of south america and to paleogeographic reconstructions in the western united states thrust belt topography is controlled by the subsurface geometry of the thrust faults particularly the positions of ramp zones and by isostatic subsidence

evaluation of an empirical radar backscatter model for predicting backscatter characteristics of geologic units at pisgah volcanic field california comparison of radar backscatter coefficients in db calculated by using the empirical model of oh et al 1992 to extracted from airsar data of four geologic units at pisgah shows that the model predicts measured vv and hv to within 3 db the model predicts higher hh than those observed for smooth surfaces rms height s s 30 the model will require modification to include surfaces with non unity hh vv

upper jurassic lower cretaceous morrison and cedar mountain formations ne utah nw colorado relationships between nonmarine deposition and early cordilleran foreland basin development abstract sedimentologic stratigraphic and petrologic analysis of the upper jurassic lower cretaceous morrison and cedar mountain formations of utah and colorado provides information on the timing and nature of early cordilleran foreland basin development the morrison formation can be subdivided into three depositional facies assemblages 1 lower progradational shallow marine lacustrine fluvial and eolian facies deposited during oxfordian kimmeridgian retreat of the stump sundance sea 2 a middle assemblage containing sandy gravelly braided fluvial deposits which are overlain by meandering fluvial channel and overbank facies and 3 an upper assemblage of laterally stable low sinuosity fluvial channel facies deposited during tithonian early neocomian time the upper part of this assemblage shows evidence of alteration and early diagenesis related to development of an early cretaceous unconformity the overlying cedar mountain formation is subdivided into two facies assemblages 1 the neocomian buckhorn conglomerate was deposited by northeast trending sandy gravelly braided rivers that were incised into the underlying morrison formation 2 an upper assemblage containing laterally stable low sinuosity fluvial channel facies deposited during late neocomian albian time the base of the unit contains a thick calcrete zone that formed during an unconformity following buckhorn deposition morrison and cedar mountain formation sandstones contain three petrofacies a feldspar rich lower morrison petrofacies qmflt 70 19 11 and chert rich upper morrison and buckhorn cedar mountain petrofacies qmflt 54 5 41 and 69 4 27 respectively sandstone composition and paleocurrent data indicate a cordilleran source area composed of proterozoic paleozoic and mesozoic sedimentary rocks the morrison formation and buckhorn conglomerate were deposited in the back bulge depozone of the late jurassic cordilleran foreland basin system and onlapped a flexural forebulge located in central utah late neocomian eastward migration of the forebulge uplifted areas in eastern utah producing an unconformity while the foredeep in central utah underwent flexural subsidence the upper part of the cedar mountain formation represents overfilling of the foredeep and deposition above the forebulge

high resolution doppler imager observations of kelvin waves in the equatorial mesosphere and lower thermosphere the behavior of kelvin waves in the mesosphere and lower thermosphere is examined in three 10 day sequences of high resolution doppler imager mesospheric and lower thermospheric zonal winds at solstice eastward propagating signatures are observed in wavenumbers 1 2 and 3 of the zonal wind field with periods near 3 and 5 days these structures are coherent in latitude and altitude and maximize near or on the equator in the mesosphere lines of constant phase move downward in time implying that these waves are forced from below above 90 km the phase lines of kelvin zonal wavenumbers 2 and 3 traverse upward in time suggesting in situ or higher level sources estimates of the eliassen palm fluxes indicate that wavenumber 1 may significantly contribute to the eastward momentum budget of the equatorial lower thermosphere

a synthetic stratigraphic model of foreland basin development the processes of erosion and deposition must be included in foreland basin models to predict correctly basin geometry and stratigraphy we present a synthetic stratigraphic model of the development of nonmarine foreland basins that predicts progressive geometry topography and facies patterns in the model steady crustal shortening occurs according to a wedgethickening model erosion and deposition follow a diffusive process and the lithosphere is compensated elastically erosion and deposition are controlled by the transport coefficients r of the diffusion equation for a range of thrust velocities and lithospheric rigidities transport coefficients are of order 102 103 m yr in the mountain belt these values are much higher than those derived from the study of scarp degradation in the sedimentary basin transport coefficients of order 104 m2 yr are appropriate and are compatible with previous studies of fluvial and deltaic deposition rapid thrusting results in a narrow underfilled basin while slow thrusting results in a wide overfilled basin in addition by varying the erosional and depositional transport coefficients while holding other parameters constant we generate both overfilled and underfilled basins these results suggest that changes in the rate of thrust loading the climate or the source rock lithology can create stratigraphic signatures that have been interpreted to record viscoelastic relaxation of the lithosphere clearly to understand either the long term behavior of the lithosphere or to interpret orogenic history from preserved foreland strata the manner in which a basin was filled must be considered we apply the model to the evolution of the modern sub andean foreland and find that an erosional transport coefficient of 3000 m2 yr and a depositional transport coefficient of 20 000 m2 yr successfully predict the observed basin geometry

deltaic deposits formed under spatially and temporally variable accommodation regimes a plausible alternative explanation for isolated shallow marine sandstone bodies sequence stratigraphic concepts and nomenclature are predicated on the assumption that at any time accommodation conditions are in phase across a depositional basin in certain situations however such as in evolving retroarc foreland basins the sense of accommodation may be spatially variable because of the growth of intrabasinal structures herein we present evidence for the accumulation of a fluvially dominated deltaic sandstone under strong forcing from spatially and temporally variable low accommodation within the cretaceous western cordilleran foreland basin of north america the peay sandstone member is a coarsening upward sandstone body thick that is extensive across much of the eastern half of the present day bighorn basin of wyoming it is remarkable for its elongate planform geometry extending many tens of kilometers across the basin and for distal thickening patterns that are at face value difficult to reconcile with conventional facies models for deltaic systems the sandstone shows some of the characteristics of falling stage and lowstand deltas extending far into the basin from the contemporary shoreline to the west lack of a preserved delta plain topset but is not incised into its substrate and does not show a descending regressive trajectory with respect to underlying strata we submit that the peay sandstone member was formed under a regime of both temporally and spatially variable accommodation forced by the heterogeneous growth of the forebulge within the western cordilleran foreland basin and suggest that the origin of some other apparently isolated sandstone bodies in this and other basins might also be explained in a similar manner

taphonomy of debris flow hosted dinosaur bonebeds at dalton wells utah lower cretaceous cedar mountain formation usa abstract a taphonomic study of the lower cretaceous dalton wells dw dinosaur bonebeds near moab utah provides insight into the origins preservational biases and paleobiological significance of one of the richest and most diverse early cretaceous dinosaur sites known the bonebeds occur in a stacked succession of debris flows at the base of the yellow cat member of the cedar mountain formation which was deposited in a seasonally dry alluvial lacustrine setting although only 5 of the locality has been collected more than 4200 bones were recovered representing an assemblage overwhelmingly dominated by dinosaurs with a minimum of 67 individuals that represent at least eight genera the assemblage also includes eight elements from four non dinosaurian reptiles the dinosaur fauna is sauropod dominated mni minimum number of individuals 41 a basal macronarian mni 15 venenosaurus mni 3 a camarasaurid mni 2 and a large number mni 21 of generically unassigned sauropod elements other dinosaurs include the theropods utahraptor mni 9 nedcolbertia mni 2 a possible ornithomimid mni 2 plus a large iguanodontid mni 4 and the ankylosaurid gastonia mni 9 patterns of skeletal articulation and clustering ontogenetic representation and bone surface modification indicate that the assemblage accumulated and was exposed for more than a year as the result one or more multiple mass mortality events likely droughts that culled large numbers of subadults from the biocoenose carcasses and disarticulated elements were reworked then later transported a short distance and buried by a succession of debris flows skeletal representation data patterns of sorting breakage burrows abrasion and scratch marks provide evidence for sorting trampling and scavenging prior to debris flow reworking pre debris flow sorting is attributed to earlier hydraulic winnowing of easily transported elements the intensity and thoroughness of breakage involving 97 of the elements suggest highly focused high load impacts compatible with trampling by sauropods and iguanodontids lightly abraded and vertically displaced elements indicate episodes of trampling in soft mud trampling occurred before and after debris flow transport theropod tooth marks are uncommon but bone scavenging by osteophagous insects was common and severe resulting in substantial damage to articular surfaces comparisons of dw and other debris flow hosted bonebeds indicate that there are few consistent patterns among fossil assemblage and bone modification data however there are numerous similarities in the geological and spatial taphonomy datasets from these sites resulting from the similar physico hydraulic conditions under which elements were transported reworked and buried geologically and taphonomically dalton wells is similar to the blagoveshchensk monodominant hadrosaur bonebed in the udurchukan formation of eastern russia which also is interpreted as a debris flow hyperconcentrated flow deposit dalton wells also shares geologic and taphonomic characteristics with four bonebeds southeast of the town of green river utah and all occur at the base of the yellow cat member the uniform stratigraphic occurrences of the dalton wells blagoveshchensk and the green river sites resting on an unconformity and their shared sedimentologic and taphonomic features indicate that these sites originated in response to similar tectonic depositional and biostratinomic factors

radar observations of long term variability of mesosphere and lower thermosphere winds over tirunelveli 8 7 n 77 8 e 1 the horizontal wind data acquired by mf radar at tirunelveli 8 7 n 77 8 e for the period january 1993 to july 2006 are used to study long term variability of equatorial mesosphere and lower thermosphere mlt winds the monthly mean zonal wind exhibits dominant semiannual variability with westward winds during equinox and eastward winds during solstice the first westward phase which occurs during spring equinox undergoes interannual variability with larger westward winds during the years 1993 1995 and 1997 this interannual variability has been interpreted as quasi biennial oscillation qbo in the mlt winds however this qbo is absent during the year 1999 as the next large westward wind phase occurs during the year 2000 thus the period of qbo is extended from nearly 2 to 3 years a during these years the period of stratospheric qbo winds is also extended to 3 a besides sao and qbo as the zonal winds undergo intraseasonal oscillations with periodicities resembling those of madden julian oscillation mjo in the troposphere the relation between the two is examined on the basis of the existing hypothesis the present study reveals long term variation in the amplitude of the annual oscillation noticed in monthly mean meridional winds a decreasing trend is observed in the annual mean northward winds during the years 1993 2006 in contrast to decreasing trend in the annual mean southward winds reported from midlatitudes these observations are discussed in the context of our current understanding of long term variability of mlt winds

lava flow characterization at pisgah volcanic field california with multiparameter imaging radar multi incidence angle in the 25 to 55 range radar data acquired by the nasa jpl airborne synthetic aperture radar airsar at three wavelengths simultaneously and displayed at three polarizations are examined for their utility in characterizing lava flows at pisgah volcanic field california pisgah lava flows were erupted in three phases flow textures consist of hummocky pahoehoe smooth pahoehoe and aa with and without thin sedimentary cover of the eight airsar images used here four were calibrated to within an accuracy of 2 db with trihedral corner reflectors and data from these calibrations were used to process the additional images to a conservatively estimated 5 db level of accuracy calibrated radar backscatter data in db were plotted as a function of incidence angle at three wavelengths p band 68 cm l band 24 cm and c band 5 6 cm and three polarizations hh horizontal transmit horizontal receive hv horizontal transmit vertical receive and vv vertical transmit vertical receive for eight major units at pisgah for which multi incidence angle airsar data were available the eight units consist of near vent and distal aa flows near vent and distal hummocky pahoehoe flows a mantled hummocky pahoehoe flow a platform pahoehoe flow an alluvial fan and a playa analyses of these backscatter data show that major unmodified volcanic units at pisgah are readily distinguishable from each other and that they exhibit diffuse hh vv and or multiple hv scattering behavior typical of rough surfaces at these wavelengths these analyses show that discrimination of smooth lavas platform pahoehoe from mantled units with greater primary roughness hummocky pahoehoe is difficult and must rely on supporting observations such as evidence of localized weathering and or sediment deposition contrast with surrounding units and superposition of flow units l band backscatter and image data at hv polarization show the best discrimination of pisgah lava flows with optimal unit separation observed between 40 and 50 incidence angles backscatter data shown as a function of relative age of pisgah flows indicate that dating of lava flows on the basis of average radar backscatter may yield ambiguous results if primary flow textures and modification processes are not well understood

satellite observations of thermospheric tides results from the wind imaging interferometer on uars thermospheric winds measured by the wind imaging interferometer windii on the upper atmosphere research satellite are analyzed for migrating solar tides the data cover a 2 year period commencing february 1992 and are obtained from the atomic oxygen o 1s 557 7 nm emission which provides observations of the 90 to 200 km altitude range during daytime and the 90 to 110 km range at night the subtropical lower thermosphere is dominated by the diurnal propagating tide which exhibits a vertical wavelength of approximately 22 km grows in amplitude up to 95 km and decays rapidly above where molecular diffusion greatly reduces the vertical shears although the phase remains fairly uniform throughout the year a pronounced semiannual oscillation is observed in the diurnal tide amplitude at both 20 n and 20 s the meridional and zonal wind components attain their maximum values at equinox of approximately 70 and 40 m s respectively while the solstitial minima are nearly a factor of 2 smaller at 35 n the diurnal tide semiannual amplitude oscillation is still present in the lower thermosphere but above 100 km it is replaced by an annual cycle with a maximum in july and august this contrasts with 35 s where the july august peak is absent and the semiannual oscillation extends to 110 km at midlatitudes the zonal and meridional winds are of similar magnitude and no significant hemispheric asymmetries in amplitudes are observed in the lower thermosphere the semidiurnal tide amplitude exhibits an annual oscillation with maximum values of 30 to 40 m s occurring in june july near 100 km at 35 n 35 s and the equator a bimodal structure in the seasonal variation of the semidiurnal phase is observed this feature is characterized by rapid equinoctial transitions and is particularly well defined at the equator examination of the equatorial middle thermosphere indicates that the semidiurnal tide attains its maximum amplitude at 140 km and exhibits a vertical wavelength of approximately 60 km these findings indicate the predominance of the antisymmetric 2 3 hough mode in the tropics

heterogeneity of the middle crust implications for strength of continental lithosphere paleoproterozoic rocks in the southwestern united states record tectonism at depths of 10 20 km during 1 75 1 65 ga amalgamation of arcs to north america these exposures of middle crust are characterized by great heterogeneity of composition structure and metamorphic grade the crust is dominated by subvertical fabric and is laterally segmented into 10 km scale blocks by subvertical shear zones metamorphic temperature gradients of 200 c occur within 10 km length scales at various 10 20 km depths hottest areas are near granitoid plutons 10 km depths or dike swarms 20 km depths and are dominated by subhorizontal foliations lowest temperature blocks depths 10 km show brittle ductile thrust belt geometries and all levels show a range of brittle semi brittle and ductile deformation features our synthesis suggests that the synorogenic middle crust exhibits a distinctive heterogeneity of tectonism influenced strongly by advective heating and resulting strength variations segmentation of the crust into tectonic blocks is interpreted to be related to the 10 km 10 m y space and time scales of plutonism and melt transfer in the middle crust by analogy to experimental data we hypothesize that the middle crust was a spatially and temporally complex strength beam during deformation with vertical fabric recording strain hardening during whole lithosphere failure heterogeneity and a dominance of vertical fabric are consistent with a general lack of middle crustal reflectivity and may have influenced differential uplift during subsequent tectonism

global variability of mesospheric temperature planetary scale perturbations at equatorial and tropical latitudes 1 the study examines the source of a cold temperature perturbation observed in the wind imaging interferometer windii daytime daily zonal mean temperatures at 87 km height during march april 1993 also seen to some extent in 1995 and 1997 over the latitude range 25 s to 25 n the perturbation appears centered at 10 s as a departure of 10k to 35k below the semiannual climatological mean which peaks at equinox after accounting for tidal contributions to the observations by adopting tidal parameters determined from the microwave limb sounder mls temperature observations the cold temperature signature still remained in the residual data the perturbation is a global phenomenon immediately following march equinox and lasts over a period of 2 weeks the period is marked by the presence of mesospheric temperature inversions over the altitude range of 70 90 km harmonic analysis reveals the presence of planetary waves of wave number 1 with periods of 3 days 4 5 days and 7 days a cross section of the temperature monthly zonal mean data and month of the year over the period from january 1992 to december 1995 revealed a distinct msao modulated by a qbo with strong cold anomalies in march april 1993 1995 and 1997 in excellent agreement with the msao easterly phase of correlative mf radar wind observations at tirunelveli 8 7 n 77 8 e it is shown that the observed temperature anomalies can be produced by the residual circulation associated with the wave driving of the msao itself

cause of tectonic reactivation and subtle uplifts in the rocky mountain region and its effect on the stratigraphic record stratigraphic studies show that widespread albeit subtle topographic uplifts have occurred throughout the u s rocky mountain region during middle and late mesozoic time individual paleotopographic highs generally have wavelengths on the order of tens of kilometres and amplitudes on the scale of metres in places these features correspond to sites of previous or later deformation and so suggest the possibility of tectonic reactivation along pre existing zones of structural weakness in the crust observations of modern features and modeling studies indicate that uplifts of small magnitude are both a common and expected result of changes in intraplate stress levels finite element modeling suggests that broad wavelength low amplitude topography can develop in a heterogeneous elastic plate under high stress magnitudes along preexisting faults and under low stress magnitudes where zones of high and low strength are juxtaposed although these features are small they have sufficient topography to bring about large changes in paleocurrent patterns for low gradient streams and significantly affect isopach patterns although subtle uplifts from this cause are difficult to predict they are likely a common occurrence and may be the most dramatic features in an area that is otherwise tectonically quiescent thus subtle uplift may be a background noise rather than a harbinger of regional orogenesis

coordinated observations of 8 and 6 hr tides in the mesosphere and lower thermosphere by three meteor radars near 60 s latitude

lower cretaceous paleo vertisols and sedimentary interrelationships in stacked alluvial sequences utah usa the yellow cat member of the cedar mountain formation in poison strip utah usa consists of stacked erosionally bounded alluvial sequences dominated by massive mudstones lithofacies fm with paleo vertisols sediment bodies within these sequences grade vertically and laterally into each other at pedogenic boundaries across which color texture and structures sedimentary vs pedogenic change slickensides unfilled sealed cracks carbonate filled cracks and deeper cracks filled with sandstone the latter features suggest thorough desiccation during aridification thin sandstones sms in some sequences typically as well as laminated to massive mudstones flm with which they are interbedded in some cases are interpreted as avulsion deposits the termini of many beds of these lithofacies curve upward parallel to nearby pedogenic slickensides as the features we call turnups turnups are overlain or surrounded by paleosols but strata sheltered underneath beds with turnups retain primary sedimentary fabrics turnups were produced by movement along slickensides during pedogenesis by differential compaction alongside pre existing gilgai microhighs or by a combination of both palustrine carbonates lithofacies c appear only in the highest or next highest alluvial sequences along with a deep paleo vertisol that exhibits partially preserved microrelief at the base of the overlying poison strip member the attributes of the yellow cat member suggest comparatively low accommodation slow accumulation long hiatuses in clastic sedimentation and substantial time intervals of subaerial exposure and pedogenesis it appears to be distinct among the members of the cedar mountain formation in these respects

doppler imager wind measurements with simulations from the ncar thermosphere ionosphere mesosphere electrodynamics circulation model in this paper a comparison is presented between simulations of the diurnal and semidiurnal tides in the middle and upper atmosphere from the thermosphere ionosphere mesosphere electrodynamics general circulation model timegcm and satellite observations from the upper atmosphere research satellite uars high resolution doppler imager hrdi reasonable agreement is found between the model and observations for a march condition when a strong diurnal tide was observed the model is able to reproduce many tidal features at altitudes between 65 and 110 km as observed in the hrdi wind measurements of interest in these features is the shortening vertical wavelength of the 1 1 tide in the upper mesosphere and lower thermosphere which appears in both model simulations and the wind observations the hrdi data also show large longitudinal variations in the diurnal tide of which the amplitude can be as high as 50 of the migrating tide the wavelike structures in latitude and altitude dimensions suggest that the longitudinal variations are likely due to the presence of propagating nonmigrating tides in the upper mesosphere and lower thermosphere for further investigations of the observed tidal variability the model demonstrates great potential with the use of more realistic heating cooling and wave forcing schemes

influence of inherited taper on structural variability and conglomerate distribution cordilleran fold and thrust belt western united states north south changes in thickness of the prethrust stratigraphy of the north american cordillera within the united states controlled kinematic development of the late mesozoic sevier fold and thrust belt variation in stratigraphic thickness determined the initial slope o of the basal decollement beneath the thrust wedge as predicted by critical wedge theory segments of the sevier thrust belt with initially thick precambrian and paleozoic stratigraphic sections are structurally simple and are composed of few thrust sheets segments with thin prethrust stratigraphy and comparably low values of o are intensely imbricated the difference in structural style resulted because wedge segments with higher values of o required less internal deformation to build and maintain the critical taper required for thrust wedge advance transverse structural zones across which kinematic style differed formed at the terminations of thrust belt segments and controlled the locations of long lived antecedent drainage systems that transported gravel to the foreland therefore along strike changes in prethrust stratigraphic thickness resulted in an observed disjunct distribution of conglomerate in synorogenic deposits of the thrust wedge and foreland basin

equatorial dynamics observed by rocket radar and satellite during the cadre malted campaign 2 mean and wave structures coherence and variability we present an analysis of the wind and temperature measurements made by rocket radar and satellite instrumentation in the equatorial and subtropical middle atmosphere accompanying the malted cadre campaign conducted at alcantara brazil during august 1994 measured mean winds and temperatures extended from 10 to 110 km exhibited general consistency between instruments and revealed an oscillatory nature of the mean zonal wind with altitude at equatorial latitudes mf radar measurements of tidal structures showed these to exhibit variability on 8 and 16 day periods but to be largely uncorrelated in time two day wave structures displayed the same periodicities but were well correlated among sites at northern and equatorial latitudes rocket and radar measurements at smaller scales of motion revealed inertia gravity waves having significant temporal coherence quadrature correlations between components indicating clear directions of propagation and momentum flux and mean wind correlations indicative of gravity wave filtering processes rocket estimates of diurnal tidal amplitudes suggest that the diurnal tide achieves convectively unstable amplitudes in the upper equatorial mesosphere

cenozoic extension and evolution of the sevier desert basin utah from seismic reflection gravity and well log data seismic reflection profiles 550 km gravity data and well log information from west central utah have been interpreted to reveal an asymmetric west dipping cenozoic basin beneath the sevier desert the basin is underlain by a 10 12 westward dipping slightly undulatory detachment surface the sevier desert detachment finite difference synthetic seismograms were used to constrain the geometry of the interpreted reflectors in the basin a two dimensional one layer gravity inversion of three gravity profiles in the basin using a 0 35 g cm density contrast corroborated the structure determined from the seismic interpretations physical properties and lithological data from eight wells were interpreted to acquire velocity depth and density depth functions and to obtain stratigraphic control a minimum width of the sevier desert detachment of 80 km to 130 km and an area of 5600 km to 9100 km was estimated primarily from the reflection data on the basis of geological and geometrical information we estimated a minimum post middle pliocene extension of 2 5 km to 3 5 km at a rate of 0 6 mm yr to 0 8 mm yr corresponding to a strain rate of 2 7 10 16 s 1 to 3 5 10 16 s 1 up to 4 0 0 6 km of predominantly post eocene lacustrine and fluvial sediments overlie the sevier desert detachment including a well defined reflection that is interpreted as a middle pliocene 4 2 m y basaltic flow that is present throughout the central and western part of the basin the geometry of the middle pliocene reflector a variable 300 to 1500 m post middle pliocene offset of a 40 eastward dipping western basin bounding fault and up to 6 km east and west stepping of the generally north trending western basin bounding fault suggests a complex late tertiary deformational history the varying deformational pattern may be a response to a changing geometry of the underlying detachment surface

flexural versus dynamic processes of subsidence in the north american cordillera foreland basin 1 dynamic subsidence related to subduction is an important process in retroarc foreland basin systems dynamic subsidence in the north american retroarc foreland has been proposed as dominant in the late cretaceous however questions remain about the nature of the subcrustal load and the basin response to such processes we present new isopach data using 130 data points covering a large portion of the u s and a revised flexural analysis of the sevier foreland higher rigidity associated with the wyoming craton can best model flexural subsidence directly prior to 81 ma we constrain the transition from flexural to nonflexural subsidence to 81 ma and correlate this with large late cretaceous progradation the locus of subsidence and the location of the subducted shatsky oceanic plateau suggest that dynamic loading from viscous flow above the subducting plate is the mechanism driving dynamic subsidence in the retroarc foreland basin of the north american cordillera

late paleogene extensional collapse of the cordilleran foreland fold and thrust belt the cordilleran foreland fold and thrust belt collapsed and spread to the west during a middle eocene to early miocene ca 49 20 ma episode of crustal extension the sedimentary and structural record of this event is preserved in a network of half grabens that extends from southern canada to central utah extensional structures superposed on this allochthonous terrain are rooted to the physical stratigraphy structural relief and sole faults of preexisting thrust fold structures the sole faults dip 3 6 west above an undeformed precambrian crystalline basement and accommodated tectonic transport of a thick up to 20 km eastward tapering hanging wall during regimes of crustal shortening and extension the chronology of tectonism for the foreland fold and thrust belt is established here by dating latest thrusting and initial normal faulting and is best defined where thrusts and normal faults are linked by common detachment surfaces dated movement on two extensionally reactivated thrusts the lewis thrust of northwest montana and southeast british columbia and the medicine butte thrust of southwest wyoming and northeast utah suggests that the hiatus between the end of crustal shortening in the early or early middle eocene and the start of extension in the early middle eocene was brief lateral spreading and extensional basin formation in the cordilleran foreland fold and thrust belt were partly concurrent with formation of metamorphic core complexes and regional magmatism conceptually linking extensional processes that were simultaneously deforming both the hinterland and foreland of the late paleogene cordilleran orogenic wedge is accomplished by applying the extensional wedge coulomb critical taper model the rapid drop in north america pacific plate convergence rate and or steepening of the subducted oceanic slab at ca 50 ma resulted in a large reduction in east west horizontal compressive stress in the cordillera as a result the cordilleran orogenic wedge was left unsupported and it gravitationally collapsed and horizontally spread west until a new equilibrium was established at ca 20 ma subsequently crustal extension and magmatism during the basin and range event ca 17 0 ma overprinted much of this earlier phase of extension

correlation of aptian albian carbon isotope excursions in continental strata of the cretaceous foreland basin eastern utah u s a abstract nodular carbonates calcretes in continental foreland basin strata of the early cretaceous cedar mountain formation cmf in eastern utah yield 13c and 18o records of changes in the exogenic carbon cycle related to oceanic anoxic events oaes and terrestrial paleoclimate chemostratigraphic profiles of both forebulge and foredeep sections show two prominent positive 13c excursions each with a peak value of 3 0 vpdb and having background 13c values of about 6 0 vpdb these excursions correlate with the global early aptian ap7 and late aptian early albian ap12 al1 carbon isotope excursions aptian albian positive 13c excursions in the cmf also correspond to 3 4 per mil increases in carbonate 18o these phenomena record local aridification events the chemostratigraphic profile on the thinner forebulge section of the cmf is calibrated for the first time by a radiogenic u pb date of 119 4 2 6 ma on a carbonate bed and by detrital zircon u pb dates on two bounding sandstone units maximum depositional ages of 146 ma and 112 ma petrographic observations and diagenetic analyses of micritic to microsparitic carbonates from nodules indicate palustrine origins and demonstrate that they crystallized in shallow early meteoric phreatic environments meteoric calcite lines derived from cmf carbonates have 18o values ranging between 8 1 to 7 5 0 vpdb supporting an estimate of zonal mean groundwater 18o of 6 0 vsmow for an aptian albian paleolatitude of 34 n furthermore our two chemostratigraphic profiles exhibit a generally proportionate thinning of correlative strata from the foredeep on to the forebulge suggesting that there were consistently lower rates of accumulation on the forebulge during the aptian albian identification of the global aptian albian 13c excursions in purely continental strata as demonstrated in this paper opens a new avenue of research by identifying specific stratigraphic intervals that record the terrestrial paleoclimatic impacts of perturbations of the global carbon cycle

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