a numerical simulation of quasi stationary tropical convective bands a method of imposing large scale ascent on a three dimensional numerical model is introduced and this is shown to be crucial in maintaining the quasi stationary convective bands observed in gate the effects of ascent on the overall convective development are to enhance updraughts and particularly to maintain the development of new convection cells the magnitutude of the forcing is varied to show the sensitivity of growth on convergence a quasi stationary convective band aligned approximately parallel to the low level wind shear is simulated in an initial environment defined from soundings obtained from the gate ships researcher and oceanographer on 3 september 1974 the organization is therefore quite distinct from that of fast moving squall lines aligned at right angles to the shear the simulated convective system has marked dynamical similarity to the observed bands these consisted of a number of cumulonimbus cells with new cells developing on the eastern end of the hand with deeper cells to the west the cells generally travel along the line the large shear due to the strong low level jet is crucial in influencing the band development and orientation the dynamical structure of the convective band is investigated by a trajectory analysis which indicates an organized three dimensional structure the transports of heat moisture and momentum are calculated and a quasi balance between large scale ascent and cloud induced descent on a time scale of a few hours is shown to exist apparent heat sources and moisture sinks are calculated and these have a bi modal vertical structure in general agreement with those in observed tropical cloud clusters

a simple multicloud parameterization for convectively coupled tropical waves part i linear analysis abstract recent observational analysis reveals the central role of three multicloud types congestus stratiform and deep convective cumulus clouds in the dynamics of large scale convectively coupled kelvin waves westward propagating two day waves and the madden julian oscillation a systematic model convective parameterization highlighting the dynamic role of the three cloud types is developed here through two baroclinic modes of vertical structure a deep convective heating mode and a second mode with low level heating and cooling corresponding respectively to congestus and stratiform clouds a systematic moisture equation is developed where the lower troposphere moisture increases through detrainment of shallow cumulus clouds evaporation of stratiform rain and moisture convergence and decreases through deep convective precipitation a nonlinear switch is developed that favors either deep or congestus convection depending on the relative dryness of the troposphere in particular a dry troposphere

geology of panamint valley saline valley pull apart system california palinspastic evidence for low angle geometry of a neogene range bounding fault geological studies support the interpretation that northern panamint valley and saline valley southeast california form paired pull apart basins on opposite sides of the right slip hunter mountain fault zone eight to ten km of late cenozoic net slip can be established on the hunter mountain fault zone palinspastic reconstruction of northern panamint valley indicates that the valley was formed by movement on a shallow crustal low angle normal fault of 0 15 degree west dip during the last 3 0 ma this interpretation appears to contradict the notions that little extension is accomodated in the uppermost crust by low angle faulting and that the most recent extension in the basin and range province is accomodated exclusively by high angle faulting saline valley however is interpreted to have formed by extension on closely spaced rotated planar normal faults thus within one geometric system of paired pull apart basins extension appears to have been accommodated in the shallow crust in two different ways

cyclothem digital correlation and biostratigraphy across the global moscovian kasimovian gzhelian stage boundary interval middle upper pennsylvanian in north america and eastern europe the long standing difficulty of correlating pennsylvanian strata among provincial faunal regions is resolved by effecting digital correlation of major glacial eustatic cyclothems that represent high stands when certain species achieved more global distribution than usual in the late moscovian early gzhelian late desmoinesian early virgilian succession in the midcontinent united states several major cyclothems are correlated by both conodont species in common and cyclothem scale with cyclothems in russia moscow basin and ukraine donets basin and the remaining cyclothems fit into the framework by position and scale in this way the suggested event marker for the global kasimovian gzhelian stage boundary first appearance of idiognathodus simulator is supported while possible event markers for the moscovian kasimovian boundary await further evaluation

a geophysical investigation of the northern panamint valley inyo county california evidence for possible low angle normal faulting at shallow depth in the crust gravity magnetic seismic refraction electrical resistivity and magnetotelluric measurements in northern panamint valley indicate that the alluvial and pluvial fill in the basin is thin and that basement under the valley floor lies at a shallow depth contours of the bouguer gravity anomaly field do not define a low over the valley and do not mimic the mapped boundaries of alluvial fill electrical resistivity and seismic refraction measurements indicate that the playa in northern panamint valley is underlain by no more than about 200 m of sediment this is consistent with the absence of any local lows in the bouguer gravity anomaly field over the valley exceeding about 15 mgal in amplitude there are no anomalies more than 50 nt in amplitude along an east west magnetic profile across the valley floor in contrast upward continuations of magnetic profiles measured across basalt outcrops present at the valley margins still contain anomalies exceeding 75 nt in amplitude at heights of 300 m because the inferred thickness of sediment under a width between 5 and 9 km of the valley is less than 300 m it is insufficient to conceal the signal expected from such magnitized basalt buried under the sediment we interpret this finding as indicating that the valley is not underlain by basalt except at its margins which implies that the west side of the valley has moved between 6 and 10 km away from the panamint range in a direction parallel to the hunter mountain fault n55 w a balanced cross section across the valley constrains the required low angle normal fault to be between 0 5 and 3 km beneath the valley floor

cloud cluster scale circulations and the vorticity budget of synoptic scale waves over the eastern atlantic intertropical convergence zone abstract objectively analyzed upper air winds over the intertropical convergence zone of the eastern tropical atlantic are separated into components representing the mean flow westward moving synoptic scale waves and cloud cluster scale motions during the third observational period of the garp atlantic tropical experiment vorticity budget analysis is performed for the three components of the flow at the scale of cloud clusters the vorticity budgets show variability that is the same order of magnitude as the vorticity field changes caused by the passage of the easterly waves the variability patterns appear to be closely related to the phase of the wave and to cloud cluster activity it is concluded that the nonlinear contributions of cloud cluster scale motions to the average wave structure are small in the lower troposphere but are as large as any of the vorticity budget terms involving wave divergence or vertical motion in the middle and upper troposphere the implications of the results for numeri

implications of selected subsurface data on the structural form and evolution of some basins in the northern basin and range province nevada and utah

low angle normal fault system along the range front of the southwestern galiuro mountains in southeastern arizona neogene erosion along the southwestern flank of the galiuro mountains in the basin and range province of southeastern arizona has exposed multiple strands of a mid tertiary low angle normal fault system that offsets oligocene miocene and older strata this fault system along the range front is overlain unconformably by onlapping miocene pliocene basin fill but forms the structural boundary between the galiuro range and the adjacent san pedro trough and it served as the breakaway zone for the extensional detachment system associated with the nearby catalina rincon core complex younger high angle normal faults of comparatively modest displacement cut various strands of the low angle normal fault system and locally displace basin fill the antiquity and nature of the galiuro range front challenge the common assumption that all morphologically prominent blocks of the basin and range province are young relief features bounded by high angle normal faults

convective organization in evolving large scale forcing represented by a highly truncated numerical archetype abstractconsidered as a prognostic generalization of mass flux based convection parameterization the highly truncated nonhydrostatic anelastic model with segmentally constant approximation nam sca is tested with time evolving large scale forcing the 20 day gate phase iii period is taken as a major data source the main advantage of the nam sca parameterization is consistency with subgrid scale dynamics as represented by the nonhydrostatic anelastic formulation the approach explicitly generates important dynamical structures of convection e g mesoscale circulations cold pools spontaneously without further tuning or treatment as additional subcomponents as with other convection parameterizations the numerical simulation of the precipitation rate the apparent heat source and the apparent moisture sink is straightforward and reasonably insensitive to the numerical procedures however convective momentum transport by organized convection turns out to be difficult even with nam sca especially fo

convective momentum transport in a simple multicloud model for organized convection abstractconvective momentum transport cmt is the process of vertical transport of horizontal momentum by convection onto the environmental flow the significance of cmt from mesoscale to synoptic and planetary scale organized cumulus convection has been established by various theoretical and observational studies a new strategy mimicking the effect of unresolved mesoscale circulation based on the weak temperature gradient wtg approximation with a gaussian profile to redistribute the heating due to parameterized cumulus convection at the subgrid scale is adopted here to construct a cmt parameterization for general circulation models gcms two main regimes of cmt are considered an upscale squall line regime and a downscale non squall line regime an exponential probability distribution is used to select which of these two effects is active conditional on the state of the large scale shear the shear itself is used as a measure of the persistence of mesoscale organized circulation due to the presen

metamorphism within the cokkul synform evidence for detachment faulting within the metamorphic infrastructure of the norwegian caledonides 67 30 n within the cokkul synform caledonian metamorphic rocks of the middle koli nappe complex mknc are in low angle fault contact with the basement mylonites derived from the precambrian tysfjord granite gneiss in the synform the mknc is composed of four fault bounded nappes each of which has a distinct tectonic stratigraphy composed of amphibolite facies metamorphosed pelitic and psammitic schists with minor lensoidal bodies of mafic and ultramafic rocks pelitic rocks from the three structurally lowest nappes contain the low variance afm mineral assemblages gar bio staur and staur ky bio with mu qtz ilm whereas staur and ky are absent from the highest nappe the kallakvare nappe afm mineral assemblages in the three lowest nappes indicate peak metamorphic temperatures of 610 660 c and peak pressures in excess of 600 mpa mineral assemblages from the kallakvare nappe are not as diagnostic of metamorphic grade however rocks from that nappe contain coexisting plagioclases from both sides of the peristerite gap suggesting lower grade peak p t conditions than those of the structurally lower nappes in addition biotite from the lower nappes is more ti rich than biotite from the kallakvare nappe however gar bio mu plag and gar bio ky plag qtz thermobarometry suggests that all four nappes equilibrated at approximately 525 25 c and 700 100 mpa gibbs method thermodynamic modelling of garnet zoning profiles suggests that the lower three nappes followed clockwise p t paths that involved heating and compression to a metamorphic peak of approximately 575 625 c 800 mpa followed by cooling and decompression to 525 c 700 mpa p t paths calculated for the kallakvare nappe show decompression and minor heating to a peak t of 500 525 c in the lower nappes staur and ky grew during the heating phase not seen by the highest nappe the outer parts of the paths from all four nappes are approximately parallel possibly recording the emplacement of the kallakvare nappe onto the already stacked lower three nappes at some time following the metamorphic peak these p t paths suggest that the sole fault of the kallakvare nappe is a normal fault garnet zonation thus appears to record a previously unrecognized phase of uplift and tectonic thinning of the mknc this event appears to be restricted to the mknc and to have occurred prior to the emplacement of the mknc onto the tysfjord granite gneiss basement of baltoscandia under greenschist facies conditions it may have been responsible for the uplift and cooling of the mknc from 25 30 km amphibolite facies conditions prior to its emplacement onto baltoscandia under 15 20 km greenschist facies conditions the deformation zone associated with this normal fault is relatively narrow generally less than 1 m thick if this is typical of other detachment faults in the metamorphic infrastructure of the scandinavian caledonides they may be relatively common but not often recognized due to the detailed study needed to document them

a paleopedological and ichnological approach to interpreting spatial and temporal variability in early permian fluvial deposits of the lower dunkard group west virginia u s a abstract lower permian asselian deposits of the washington formation dunkard group in west virginia u s a represent proximal to distal expressions of a migrating anastomosing river and associated floodplain environments these deposits are part of the upper fluvial plain province of the dunkard basin characterized by thick to thin sandstone bodies shales and paleosols the paleosols and associated ichnofossils record a wealth of paleoenvironmental paleoecological and paleoclimatic data which improve our understanding of the autogenic and allogenic processes that result in the spatial and temporal variability of ancient fluvial systems this study integrates field and laboratory analysis of paleosols and ichnofossils including macro to micromorphology bulk geochemistry and clay mineralogy to better understand variations in soil forming processes across this early permian floodplain nine different pedotypes were identified including proximal poorly developed entisols and inceptisols poorly drained histosols and thick moderately to well drained inceptisols and vertisols lateral differences in paleosol properties were minor compared to the diversity of paleosols present in the vertical exposure and were largely a result of localized variations in drainage and topography differences in the properties of the paleosols in the vertical succession could not be explained by variable drainage due to position on the floodplain cyclicity was largely controlled by avulsion but was overprinted by changes in climate while climatic drying during the early permian as a general trend is well established smaller scale fluctuations between wet and dry intervals contributed significantly to observed paleosol properties dominance by calcareous vertisols in the upper fluvial plain facies province and their representation of strongly seasonal conditions are consistent with previous research however thorough investigation of the paleosols suggests that more humid conditions existed than the arid to semiarid climate that has been suggested

paleoenvironmental clues archived in non marine pennsylvanian lower permian limestones of the central appalachian basin usa abstract nonmarine limestones are a key component of the upper middle pennsylvanian through lower permian succession in the appalachian basin previous interpretations of their environments of deposition range from brackish coastal mudflats to hydrologically open freshwater lake complexes with peat forming vegetated marshes to semi closed or closed possibly saline shallow lakes developed on a distal alluvial plain ostracode wackestones packstones some exhibiting laminations and with fish debris articulated ostracode shells and phosphatic clasts define the lower portions of limestone beds or benches passing upward into ostracode peloidal wackestones packstones and intraclastic skeletal peloidal packstones grainstones desiccation features and rooting structures which are developed in the upper portions of the limestones record subaerial exposure pedogenic alteration and desiccation pseudomicrokarst and caliche like vadose and early diagenetic phreatic cements suggest a seasonally dry subhumid to semi arid regional climate many of the sedimentologic and diagenetic features of the limestones are characteristic of palustrine carbonates which coupled with their stratigraphic relation to paleo vertisols siliciclastics and coals indicate that they formed in broad seasonal wetland pond complexes that developed on distal regions of a low gradient distal alluvial plain under seasonally dry subhumid to semi arid climates integration of sr isotopic compositions of shark teeth with previously published stable isotope compositions of the limestones suggests that these purely continental environments were hydrologically semi closed to closed systems repeated stacking of these features at the bed to limestone bench scale defines repeated shallowing upward drying cycles at the 103 to 104 yr scale which were likely climate driven

seismic reflection constraints on the structure of the crust beneath the san bernardino mountains transverse ranges southern california a 30 km long n s seismic reflection line was shot by california consortium for crust studies calcrust across the southern mojave desert and onto the northern flank of the san bernardino mountains in southern california on the northern end of the seismic section the reflectivity increases markedly in the midcrust at a depth corresponding to a two way travel time of 4 to 5 s 12 15 km suggesting a transition between nonreflecting brittle upper crust and reflecting ductile lower crust the high reflectivity disappears at about 8 s 24 km and may be correlated with a change in seismic velocity in the lower crust from 6 3 km s to 6 8 km s a band of reflectivity between 9 5 and 10 s 27 30 km is believed to represent the moho the midcrustal relectivity transition and moho both deflect downward toward the san bernardino mountains uplift over the entire length of the profile the deflection of the midcrustal transition 12 appears greater than that of the moho 6 resulting in a thinning of the lower crust to the south beneath the uplift in addition the midcrustal transition coincides with the base of the seismogenic zone brittle ductile transition which is also dipping southward beneath the san bernardino mountains while the moho deflection is consistent with elastic flexure resulting from edge loading by the san bernardino mountains which have been thrust over the mojave block it is suggested that the thinning of the lower crust beneath the san bernardino mountains is a result of north directed ductile flow in response to loading by the over thickened upper crust since a portion of the load is transmitted through the lower crust to the moho the time constant for flow equilibrium must be of the order of or greater than that for the time of uplift 2 m y

patterns of mineral transformations in clay gouge with examples from low angle normal fault rocks in the western usa abstract neoformed minerals in shallow fault rocks are increasingly recognized as key to the behavior of faults in the elasto frictional regime but neither the conditions nor the processes which wall rock is transformed into clay minerals are well understood yet understanding of these mineral transformations is required to predict the mechanical and seismogenic behavior of faults we therefore present a systematic study of clay gouge mineralogy from 30 outcrops of 17 low angle normal faults lanf s in the american cordillera to demonstrate the range and type of clay transformations in natural fault gouges the sampled faults juxtapose a wide and representative range of wall rock types including sedimentary metamorphic and igneous rocks under shallow crustal conditions clay mineral transformations were observed in all but one of 28 faults one fault contains only mechanically derived clay rich gouge which formed entirely by cataclasis clay mineral transformations observed in gouges show four general patterns 1 growth of authigenic 1m d illite either by transformation of fragmental 2m 1 illite or muscovite or growth after the dissolution of k feldspar illitization of fragmental illite smectite is observed in lanf gouges but is less common than reported from faults with sedimentary wall rocks 2 retrograde diagenesis of an early mechanically derived chlorite rich gouge to authigenic chlorite smectite and saponite mg rich tri octahedral smectite 3 reaction of mechanically derived chlorite rich gouges with mg rich fluids at low temperatures 50 150 c to produce localized lenses of one of two assemblages sepiolite saponite talc lizardite or palygorskite chlorite quartz and 4 growth of authigenic di octahedral smectite from alteration of acidic volcanic wall rocks these transformation groups are consistent with patterns observed in fault rocks elsewhere the main controls for the type of neoformed clay in gouge appear to be wall rock chemistry and fluid chemistry and temperatures in the range of 60 180 c

sequence stratigraphy and onlap history of the donets basin ukraine insight into carboniferous icehouse dynamics abstract the degree to which permo carboniferous cyclothemic successions archive evidence for long term variations in ice volume during the late paleozoic ice age is insufficiently resolved here we develop the sequence stratigraphy and onlap offlap history for a 33 my interval of the carboniferous using the u pb calibrated succession of the donets basin ukraine in order to assess the relationship between sea level high latitude changes in glacial extent and climate integrated subsurface and outcrop data permit meter scale correlation of 242 biostratigraphically constrained limestones and coals and in turn individual cyclothems across 250 km of the donets basin rapid uniform subsidence and basinwide continuity of marker beds indicate pennsylvanian deposition under relatively stable tectonic conditions three scales of sequences avg durations of 140 ky 480 ky and 1 6 my are recognized on the basis of stratigraphic stacking patterns and basinwide architecture of marine to terrestrial facies assemblages the hierarchy of sequences and the geographic and stratigraphic positions of shifts in base level sensitive facies across the donets ramp permit the construction of an onlap offlap history at a sub 400 ky scale major sea level lowstands occur across the mid carboniferous boundary and during the early moscovian these lowstands coincide with glacial maxima inferred from high latitude glacigenic deposits the middle to late pennsylvanian is characterized by a stepwise onlap culminating in an earliest gzhelian highstand suggesting contraction of carboniferous ice sheets prior to the initiation of early permian glaciation the stratigraphic position of climate sensitive facies within individual donets cyclothems indicates a turnover from seasonal sub humid or semi arid climate to everwet conditions during the late lowstand and maximum ice sheet accumulation comparison of the stratigraphic and aerial distribution of coals and evaporites in the donets basin with the onlap offlap history further indicates everwet conditions during lowstands and inferred glacial maxima and drier climate during onlap and inferred ice sheet contraction at the intermediate 0 8 to 1 6 my and long 106 yr time scales taken together the relationship between inferred climate and glacioeustasy suggests a likely teleconnection between high latitude ice sheet behavior and low latitude atmospheric dynamics

distribution and provenance of the middle miocene eagle mountain formation and implications for regional kinematic analysis of the basin and range province conglomeratic strata from middle miocene sections in the central resting spring range and nearby eagle mountain california contain a clast assemblage including marble orthoquartzite fusulinid grainstone and coarse 1 m monzogabbro interstratified with tephras yielding laser fusion 40 ar 39 ar ages of 11 6 13 4 and 15 0 ma petrographic and geochronologic evidence ties the clast assemblage to a source area in the southern cottonwood mountains california 100 km west northwest of their present location in the upper 100 m of the resting spring range section conglomerates are derived almost exclusively from the southern cottonwoods source and sandstone modes are as much as 50 angular plagioclase derived from the monzogabbro the lack of dilution of this detritus by other sources and sedimentary features in both sections indicate 1 that deposition occurred on an alluvial fan with a north northeast paleoslope and 2 that transport of the gravels by sedimentary processes was probably 20 km north northeast in a direction normal to the present azimuth to their source therefore we interpret most or all of the net east southeast transport as a result of extensional and strike slip faulting between the cottonwood mountains and the resting spring range since 11 12 ma restoration of these deposits to a position 10 20 km north northeast of the eastern margin of the monzogabbro source east margin of the hunter mountain batholith yields a net tectonic displacement of the cottonwood mountains relative to the resting spring range of 104 km n67 w this result confirms previous reconstructions based on the restoration of isopachs in the cordilleran miogeocline pre cenozoic structural features and other proximal tertiary deposits in the region

sequence stratigraphy of the late carboniferous clifton formation new brunswick the maritimes basin of atlantic canada contains a rich record of pennsylvanian cyclothems previous studies have focused on rapidly subsiding depocenters in the central part of the basin where carb

organizational modes of midlatitude mesoscale convective systems this paper discusses common modes of mesoscale convective organization using 2 km national composite reflectivity data the authors investigated linear mesoscale convective systems mcss that occurred in the central united states during may 1996 and may 1997 based upon the radar observed characteristics of 88 linear mcss the authors propose a new taxonomy comprising convective lines with trailing ts leading ls and parallel ps stratiform precipitation while the ts archetype was found to be the dominant mode of linear mcs organization the ls and ps archetypes composed nearly 40 of the studied population in this paper the authors document the characteristics of each linear mcs class and use operational surface and upper air data to describe their different environments in particular wind profiler data reveal that the stratiform precipitation arrangement associated with each class was roughly consistent with the advection of hydrometeors implied by the mean middle and upper tropospheric storm relative winds which were significantly different among the three mcs modes case study examples are presented for both the ls and ps classes which have received relatively little attention to this point as well the authors give a general overview of the synoptic scale meteorology accompanying linear mcss in this study which was generally similar to that observed by previous investigators

sea level curve for pennsylvanian eustatic marine transgressive regressive depositional cycles along midcontinent outcrop belt north america at least 55 cycles of marine inundation and withdrawal are recognized in the mid desmoinesian to mid virgilian midcontinent outcrop sequence in north america they range from widespread major cycles classic cyclothems with deep water facies extending across the northern shelf through intermediate cycles persisting as marine horizons across the shelf to minor cycles developed on the lower shelf or as parts of major cycles biostratigraphic differentiation of the cycles should establish interbasinal correlation on a scale fine enough to allow evaluation of differential tectonics and sedimentation sequential groupings of cycles are more irregular than proposed megacyclothems or mesothems but they may be obscured by the distinctness of the major cyclothems estimates of cycle periods range from about 40 to 120 x 10 sup 3 yr for the minor cycles up to about 235 to 400 x 10 sup 3 yr for the major cyclothems the range for all cycles corresponds well to the range of periods of earth s orbital parameters that constitute the milankovitch insolation theory for the pleistocene ice ages and it further supports gondwanan glacial control for the pennsylvanian cycles even though the dominant period of the major pennsylvanian cyclothems is up to four times longer than the dominant 100 000 yr period inmore the pleistocene the shapes of both curves display rapid marine transgression rapid melting of ice caps and slow interrupted regression slow buildup of ice caps which suggest similar linkages between the climatic effects of the orbital parameters and ice cap formation and melting at the two different scales widely separated in time 28 references 3 figures less

nam sca a nonhydrostatic anelastic model with segmentally constant approximations an atmospheric convective system may be modeled as an ensemble of discrete plume elements a representation of decomposited plumes provides the basis for mass flux convective parameterization a dry version of such a prototype model is constructed in a two dimensional horizontally periodic domain each discrete plume element is approximated by a horizontally homogeneous segment such that the whole system is given by segmentally constant approximations sca in the horizontal direction for each vertical level in a nonhydrostatic anelastic model nam the distribution of constant segments is highly inhomogeneous in space and evolves with time in a highly adaptive manner the basic modeling strategy from a physical point of view is to activate new segments vertically upward with time when a convective plume is growing and to deactivate segments when a plume event is over the difference in physical values crossing segment interfaces is used as a criterion for numerically implementing this strategy whenever a large difference is found the given interface is stretched vertically by subdividing an existing segment into two in turn when a segment interface difference is found below the threshold the given interface is removed thereby merging the two segments into one this nonhydrostatic anelastic model with segmentally constant approximations nam sca is tested on an idealized atmospheric convective boundary layer it successfully simulates the evolution of convective plumes with a relatively limited number of segments i e high compression and with a much scarcer distribution of segments over nonplume environments i e extremely inhomogeneous distribution of segments overall this method compresses the size of the model up to 5 times compared to a standard nam with homogeneous grid distribution without substantially sacrificing numerical accuracy

the role of environmental shear and thermodynamic conditions in determining the structure and evolution of mesoscale convective systems during toga coare abstract a collection of case studies is used to elucidate the influence of environmental soundings on the structure and evolution of the convection in the mesoscale convective systems sampled by the turboprop aircraft in the tropical ocean global atmosphere toga coupled ocean atmosphere response experiment coare the soundings were constructed primarily from aircraft data below 5 6 km and primarily from radiosonde data at higher altitudes the well documented role of the vertical shear of the horizontal wind in determining the mesoscale structure of tropical convection is confirmed and extended as noted by earlier investigators nearly all convective bands occurring in environments with appreciable shear below a low level wind maximum are oriented nearly normal to the shear beneath the wind maximum and propagate in the direction of the low level shear at a speed close to the wind maximum when there is appreciable shear at middle levels 800 400 mb convective bands form parallel to the shear with

three dimensional model of the late cenozoic history of the death valley region southeastern california the accumulation of a large database on the timing and kinematics of late cenozoic deformation in the death valley region of southeastern california indicates a complex three dimensional history on the basis of paleogeographic reconstructions we suggest the system was initiated as a localized pull apart between two conjugate strike slip faults the garlock and furnace creek faults and evolved into a system characterized by distributed transtension related to the eastern california shear zone our reconstructions differ from previous models in the incorporation of significant vertical axis rotations of a number of crustal blocks to explain paleomagnetic data from the region the model may resolve 1 a long standing problem of the eastern termination of the garlock fault which is explained here as a complex system of splays that initially terminated in the pull apart between the furnace creek and garlock systems and 2 the complex architecture of the black mountains which is explained here in terms of initial extreme attenuation between the garlock and furnace creek systems with overprinting by a fold and normal fault system that operated simultaneously as a result of distributed transtension this model suggests much of the displacement field is taken up in rotations and translations and the actual crustal thinning in our model is relatively small 50 66 of original thickness

large camborygma isp in fluvial deposits of the lower permian asselian dunkard group southeastern ohio u s a abstract the lower washington formation of the lower permian asselian dunkard group in southeastern ohio contains large burrows exposed in cross section in a laterally discontinuous sandstone bed this study examined the morphology of the burrows and their associated lithofacies to interpret the environmental conditions under which they were produced as well as the behavior and identity of the trace maker mudstone facies below and above the burrow bearing sandstone consist of reddish brown to variegated paleosols containing rhizohaloes argillans and large scale slickensides as well as thinly laminated organic rich shales containing plant fossils the sandstone facies is 94 147 cm thick thinly bedded to massive and fine to medium grained the lithofacies are interpreted as deposits of crevasse splays abandoned channels and proximal to distal floodplains sixty burrows consist of vertical subvertical j shaped y shaped and complex networks of branching shafts and tunnels the burrows range from 5 to 180 cm in length and 0 8 3 6 cm in width the main shaft s angles are typically 90 although are rarely 30 70 branching angles of subvertical and y shaped burrows vary from 0 to 90 many burrows extend to the top of the sandstone bed but others turn into or out of the bed the morphology of the burrows is most similar to camborygma known from continental deposits of the permian to recent while camborygma has been previously reported from the permian this is the first occurrence in the late paleozoic appalachian basin extending its geographic range the dunkard burrows are similar to those of modern freshwater decapods particularly crayfish decapod body fossils are not known from the dunkard group yet these burrows are highly suggestive of their presence therefore these fossil burrows contribute to the paleoecological interpretation of the dunkard group helping to fill in gaps of the terrestrial fauna not otherwise preserved in the fossil record decapod burrow morphologies are highly variable depending on burrow function and environment the dunkard burrows are similar to secondary dwellings with few open water attachments multiple branches and shafts likely extending to the water table

numerical archetypal parameterization for mesoscale convective systems abstractvertical shear commonly organizes atmospheric convection into coherent multiscale structures the associated countergradient vertical transport of horizontal momentum by organized convection can enhance the wind shear and transport kinetic energy upscale however organized convection and its upscale effects are not represented by traditional mass flux based parameterizations the present paper sets the archetypal dynamical models originally formulated by the second author into a parameterization context by utilizing a nonhydrostatic anelastic model with segmentally constant approximation nam sca using a two dimensional framework as a starting point nam sca spontaneously generates propagating tropical squall lines in a sheared environment high numerical efficiency is achieved through a novel compression methodology the numerically generated archetypes produce vertical profiles of convective momentum transport that are consistent with the analytic archetype

cloud resolving modeling of cloud systems during phase iii of gate part ii effects of resolution and the third spatial dimension abstract two and three dimensional simulations of cloud systems for the period of 1 7 september 1974 in phase iii of the global atmospheric research programme garp atlantic tropical experiment gate are performed using the approach discussed in part i of this paper the aim is to reproduce cloud systems over the gate b scale sounding array comparison is presented between three experiments driven by the same large scale conditions i a fully three dimensional experiment ii a two dimensional experiment that is an east west section of the three dimensional case and iii a high resolution version of the two dimensional experiment differences between two and three dimensional frameworks and those related to spatial resolution are analyzed the three dimensional experiment produced a qualitatively realistic organization of convection nonsquall clusters a squall line and scattered convection and transitions between regimes were simulated the two dimensional experiments produced convective organ

dunkard group coal beds palynology coal petrography and geochemistry abstract coal beds that occur in the dunkard group are typically thin avg 0 3 m and are high in ash yield avg 27 8 and total sulfur content avg 5 1 petrographically dunkard coals are high in vitrinite avg 83 1 mmf with correspondingly low to moderate amounts of liptinite avg 2 1 mmf and inertinite avg 13 8 mmf palynologically dunkard coal beds are all dominated by tree fern spore taxa avg 96 3 especially punctatisporites minutus avg 82 8 calamite spores are the second most abundant plant group avg 2 4 with others lycopods small ferns cordaites and other gymnosperms having very minor representation overall the coal palynofloras are strongly dominated by lowland plants ferns and calamites with only rare occurrences of bisaccate striate conifer pollen coal beds of the underlying monongahela group pittsburgh redstone sewickley and waynesburg are thicker avg 1 6 m and are lower in ash avg 13 4 and sulfur avg 3 3 than their dunkard counterparts petrographically monongahela group coals are very similar to dunkard group coals when compared on a mineral matter free basis coal beds that occur in both groups are strongly dominated by vitrinite macerals monongahela group coals are also palynologically very similar to dunkard group coals with tree fern spore taxa dominating a coal bed of early permian age from west central texas is also similar petrographically and palynologically to dunkard and monongahela coals being vitrinite and tree fern spore dominant the almost complete lack of coniferous pollen in dunkard coals led earlier workers to conclude that the dunkard was entirely late pennsylvanian and not permian in age however it is now known that late pennsylvania lowland floras persisted into the dunkard especially during wet intervals as earlier interpretations were based primarily on spore and pollen floras from coal beds the lack of conifer pollen in dunkard coals is probably the result of a sampling bias because of this ecological bias coal palynology is a poor proxy for age dating dunkard group coals collectively dunkard swamps were all planar and topogenous their formation being controlled by topography and moisture availability a progressive decrease in wet intervals both in terms of frequency and duration during the dunkard was the major control on peat accumulation and preservation collectively moisture limitation appears to be the principle factor that controlled the formation of dunkard group coals

the basin and range province origin and tectonic significance the basin and range province is a vast arid tract of regionally corrugated angular topography of high relief in the western cordillera it is characterized by evenly spaced parallel mountain ranges and intervening desert basins fig ure la the range flanks are marked by poorly sorted gravel aprons that slope smoothly basinward interrupted here and there by low fault scarps that paral lel the range front faults and by alluvial fans at the mouths of canyons draining the ranges thermal springs located at or near range bounding faults attest to vigorous hydrothermal circulation within zones of fracture porosity created and maintained by faulting in the southern part of the province especially in southeastern california and southwestern arizona range fronts have been worn back by erosion leaving a thin veneer of gravel on an erosion cut bedrock surface that slopes gently outward the range bounding faults of these mountain blocks are buried at the outer edge of such pediments often at considerble distances from the erosional remnants of the ranges themselves the american physiographer n m fenneman 1928 1931 named the basin and range province and defined its general boundaries as thus circum scribed the province includes some 800 000 km2 of area in eight western states later students pardee 1950 lawrence 1976 reynolds 1979 eaton 1979b have observed that many of the fundamental geological and geo physical characteristics of the province are found well beyond the boundaries drawn by fenneman which were based on physiography alone as a tec tonophysical entity its areal extent is greater than 1 million km2 more than 10 of the area of the united states figure 1 fenneman 1931 subdivided the province into five physiographic sections the largest of which is the great basin see figure 1b it is not as its name implies a single regional depression with a common topographic center but is characterized instead by isolated networks of interior drainage divisible into

convection in gate the difficult problem of parameterizing tropical convection in large scale models of the atmosphere led to the global atmospheric research program s atlantic tropical experiment gate whose goal was to improve basic understanding of tropical convection and its role in the global atmospheric circulation a dense network of instrumented ships equipped with upper air sounding equipment and quantitative weather radars were located over the atlantic ocean in the intertropical convergence zone itcz just west of equatorial africa the ship network was supplemented by a fleet of research aircraft and a geosynchronous meteorological satellite the data obtained show that the deep convection in the itcz was concentrated in two types of cloud clusters rapidly moving squall clusters and slowly moving nonsquail clusters the clusters were characterized by large mid to upper level cloud shields or anvil clouds that emanated from penetrative cumulonimbus convection accompanying the deep cumulonimbus in each cluster was a log normal spectrum of smaller convective features ranging from moderate cumulonimbus down to tiny nonprecipitating cumulus the large cumulonimbus were typically grouped within a cluster into one or more mesoscale precipitation features or mpf s which were apparently triggered in mesoscale regions of intensified low level convergence as an mpf matured it developed a region of stratiform precipitation adjacent to its active deep convective cells the stratiform precipitation fell from the anvil cloud associated with the stratiform precipitation were a mesoscale downdraft below the anvil cloud and an apparent mesoscale updraft within the anvil cloud itself above the mesoscale downdraft these mesoscale drafts were distinct from the convective scale updrafts and downdrafts of the cumulus and cumulonimbus cells of the cluster downdrafts both convective scale and mesoscale filled the planetary boundary layer in the vicinity of cumulonimbus with stable air of low moist static energy these wakes of downdraft air exerted a strong control on where future convection broke out the results of gate show that to simulate the effects of tropical convection in large scale numerical models of the atmosphere a variety of phenomena must be accounted for including not only convective scale updrafts and downdrafts but anvil clouds with mesoscale updrafts and downdrafts downdraft induced boundary layer transformations and mesoscale convergence patterns experimentation with ways of including some of these features of tropical convection in large scale diagnostic and prognostic studies is under way but much work remains to be done

shear parallel mesoscale convective systems in a moist low inhibition mei yu front environment abstractnumerical simulations are performed to investigate organized convection observed in the asian summer monsoon and documented as a category of mesoscale convective systems mcss over the u s continent during the warm season in an idealized low inhibition and unidirectional shear environment of the mei yu moisture front the structure of the simulated organized convection is distinct from that occurring in the classical quasi two dimensional shear perpendicular and trailing stratiform ts mcs consisting of four airflow branches a three dimensional eastward propagating downshear tilted shear parallel mcs builds upshear by initiating new convection at its upstream end the weak cold pool in the low inhibition environment negligibly affects convection initiation whereas convectively generated gravity waves are vital upstream propagating gravity waves form a saturated or near saturated moist tongue and downstream propagating waves control the initiation and growth of convection within a pre

cainozoic evolution of the state of stress and style of tectonism of the basin and range province of the western united states cainozoic evolution of the modern plate boundary along the western united states from subduction to a predominantly transform boundary coincided with a change from compressional to extensional deformation in the western united states extensions tectonism responsible for the modern basin and range province appears to represent a unique late stage episode of a much longer period of extension initiated in an in tra arc setting contemporaneously with calc alkaline magmatism basin range extension is distinguished from early extension on the basis of angular unconformities differences in fault trends and spacing and associated magmatism basaltic prebasin range extension i e extension preceding the break up of the region into ranges resembling the modern ones was under way locally by at least 30 ma and is now recognized by faulted and highly tilted strata exposed in uplifted range blocks by large regions of the crust underlain by passively emplaced subvolcanic batholiths and by the thickness and distribution of stratigraphic units locally high strain rates that accompanied early extensions of as much as 50 100 are implied data on preferentially orientated dyke swarms and fault slip vectors indicate a strikingly uniform wsw ene least principal stress orientation in the period ca 20 10 ma during this early extension the change from early extension to basin range style faulting of the upper 15 km of crust which resulted in broadly spaced ranges 25 35 km crest crest spacing was time transgressive and probably not abrupt locally both types occurred concurrently southern basin and range block faulting occurred largely in the period 13 10 ma in response to a stress field orientated similarly to that responsible for the early extension in contrast northern basin and range block faulting developed after 10 ma and continues to the present in response to a stress field orientated approximately 45 clockwise to the earlier stress field this modern stress field with a wnw ese to e w directed least principal stress characterizes the entire modern basin and range province and rio grande rift region the 45 change in least principal stress orientation is consistent with superposition of dextral shear associated with the development of the san andreas transform fault inclusion of pre basin range extension may help resolve the discrepancy between estimates of 15 30 for basin range block faulting and total extension estimates of 100 300 for the basin and range province

curie point depth estimates from aeromagnetic data from death valley and surrounding regions california aeromagnetic data were analyzed to determine the curie point depth cpd by power density spectral and three dimensional inversion methods within and surrounding death valley in southern california we calculated the cpd for 0 5 regions using 2d power density spectral methods and found that the cpds varied between 8 and 17 km however the 0 5 region may average areas that include shallow and deep cpds and because of this limitation we used the 3d inversion method to determine if this method may provide better resolution of the cpds the final 3d model indicates that the depth to the bottom of the magnetic susceptible bodies varies between 5 and 23 km even though both methods produced roughly similar results the 3d inversion method produced a higher lateral resolution of the cpds the shallowest cpds occur within the central and southern death valley panamint valley coso geothermal field and the tecopa hot springs region deeper 15 km cpds occur over outcropping granitic and precambrian lithologies in the panamint range grapevine mountains black mountains and the argus range the shallowest cpd occurs within the central death valley over a possible seismically imaged magma body and slightly deeper values occur within the panamint valley southern death valley and tecopa hot springs the shallow cpd values suggest that partially molten material may also be found in these latter regions the cpd computed heat flow values for the region suggest that the entire area has high heat flow values 100 mw m 2 on the other hand locally extremely high values 200 mw m 2 occur within the panamint valley the southern and central death valley and tecopa hot springs region these locally high heat flow values may be related to midcrustal magma bodies but additional geophysical experiments are needed to determine if the magma bodies exist

surficial offsets on the central and eastern garlock fault associated with prehistoric earthquakes geomorphic features offset along the central and eastern garlock fault record the amount of surface slip associated with prehistoric earthquakes along the easternmost 90 km of the fault the smallest offsets cluster around 2 3 m of left lateral slip apparently associated with the most recent earthquake on this portion of the fault larger offsets along this part of the fault especially in pilot knob valley cluster around values consistent with 2 4 m of slip in each of the past several events farther west south of el paso mountains offset geomorphic features suggest that each of the past two earthquakes on this stretch of the garlock fault was produced by about 7 m of slip whereas the third event back was produced by about 4 m of slip vertical displacements of geomorphic features range from 0 to 30 of the left lateral offsets within pilot knob valley along the southern side of the slate range vertical displacements are consistently up on the northern side whereas within the avawatz mountains both north and south side up vertical displacements are present on the basis of the geomorphic offsets the geometry of the garlock fault and the precedents set by historical strike slip earthquakes elsewhere a number of different rupture patterns are plausible these range from rupture of the entire garlock fault in a single event with a maximum magnitude of about mw 7 8 to separate rupture of the western segment and of the central and eastern segments combined with approximate magnitudes mw 1 1 and mw 7 5 respectively to separate rupture of even shorter segments producing earthquakes of magnitudes mw 6 6 to mw 7 5 in conjunction with available slip rates for the garlock fault the geomorphic offsets suggest that average recurrence intervals are probably within the range of 600 1200 years south of el paso mountains about 200 750 years in searles valley about 200 1300 years in pilot knob valley and about 200 3000 years near leach lake and in the avawatz mountains

stochastic models for convective momentum transport the improved parameterization of unresolved features of tropical convection is a central challenge in current computer models for long range ensemble forecasting of weather and short term climate change observations theory and detailed smaller scale numerical simulations suggest that convective momentum transport cmt from the unresolved scales to the resolved scales is one of the major deficiencies in contemporary computer models here a combination of mathematical and physical reasoning is utilized to build simple stochastic models that capture the significant intermittent upscale transports of cmt on the large scales due to organized unresolved convection from squall lines properties of the stochastic model for cmt are developed below in a test column model environment for the large scale variables the effects of cmt from the stochastic model on a large scale convectively coupled wave in an idealized setting are presented below as a nontrivial test problem here the upscale transports from stochastic effects are significant and even generate a large scale mean flow which can interact with the convectively coupled wave

polymetamorphism in the panamint mountains california a 39ar 40ar study metamorphosed upper precambrian rocks in the panamint mountains show textural evidence for polymetamorphism previous isotopic studies have established the age of metamorphism as middle to late mesozoic this study was undertaken to try to determine the ages of the two metamorphic events using the 39ar 40ar stepwise degassing technique of the k ar method on biotite muscovite and hornblende separates the resulting spectra indicate that metamorphism occurred during the intervals 170 150 ma ago and 80 70 ma ago many analyses yield ambiguous results because of slow cooling following metamorphism contamination of the separates by refractory phases containing extraneous argon and in some cases the superposition of the two metamorphic events the ages of metamorphism correspond to periods of emplacement of granitic rocks in the vicinity of the panamint mountains suggesting that the high heat flux responsible for metamorphism was associated with the emplacement of the sierra nevada batholith the ages of metamorphism and granite emplacement are diachronous with the development of major thrust faults in the western great basin which suggests that metamorphism might have been triggered by the formation of nappes rather than causing the formation of nappes

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

multiscale waves in an mjo background and convective momentum transport feedback abstractthe authors use linear analysis for a simple model to study the evolution of convectively coupled waves ccws in a background shear and background moisture mimicking the observed structure of the madden julian oscillation mjo this is motivated by the observation in an idealized setting of intraseasonal two way interactions between ccws and a background wind it is found here that profiles with a bottom heavy moisture content are more favorable to the development of mesoscale squall line like waves whereas synoptic scale ccws are typically more sensitive to the shear strength the mjo envelope is thus divided into three regions in terms of the types of ccws that are favored an onset region in front that is favorable to kelvin waves a mature or active region in the middle in which squall lines are prominent and the stratiform and decay phase region in the back that is favorable to westward inertia gravity wig waves a plausible convective momentum transport cmt feedback is then provide

quaternary faulting history along the deep springs fault california new geologic mapping structural studies geochronology and diffusion erosion modeling along the deep springs fault california shed light on its quaternary faulting history the deep springs fault a 26km long predominantly north northeaststriking west northwestdipping normal fault bounding the eastern side of deep springs valley cuts jurassic batholithic rocks nonconformably overlain by middle miocene to pleistocene stream gravels coarse grained sand tuffaceous sand unwelded to partially welded tuff and bishop ash as well as quaternary coarse to finegrained alluvial fan deposits the 40 ar 39 ar geochronology yields ages of 3 09 0 08 ma for the unwelded tuff and 753 4k a for the bishop ash holocene debris flows a landslide and recent alluvium bury the youngest fault scarp the deep springs fault is characterized by multiple fault planes and fault scarps that become progressively younger toward the basin the dip of the fault plane varies from 20 to 87 and fault plane and striation measurements indicate an average orientation of n23e 47nw and n77e 49sw respectively the offset of bishop ash and underlying tuff across the deep springs fault indicates horizontal extension and vertical slip rates of 0 7 and 0 9 mm yr respectively since the eruption of the bishop tuff and 0 2 and 0 2 mm yr respectively since the eruption of the unwelded tuff if the vertical slip rate since the eruption of the bishop tuff has remained constant through time then slip along the deep springs fault began ca 1 7 ma younger fault scarps to the west of the bedrock fault cut quaternary deposits scarp offset ranges from 0 8 to 17 5 m and scarp slope angle ranges from 8 to 37 topographic profiling of the smallest least eroded fault scarps with an average surface offset of 2 7 m indicates that these scarps developed as the result of a single earthquake and ruptured an 20km long segment of the fault radiocarbon analyses on detrital charcoal located in the footwall block of one of these scarps yield an age of 1 960 0 055 ka diffusion erosion modeling of these fault scarps yields an elapsed time of 1 7 0 5 k y since these fault scarps formed making reasonable assumptions about the depth of this earthquake and shear modulus we estimate a moment magnitude mw 7 0 for this earthquake the deep springs fault is one of several displacement transfer normal faults that define a zone of distributed deformation between subparallel right lateral strike slip faults east of the sierra nevada that make up the northern part of the eastern california shear zone the young age and recent earthquake activity along the deep springs fault are consistent with a model proposed for the kinematic evolution of this part of the eastern california shear zone

vertebrate biostratigraphy and biochronology of the upper paleozoic dunkard group pennsylvania west virginia ohio usa abstract the dunkard group is 343 m of mostly clastic rocks exposed in pennsylvania ohio and west virginia usa correlation of the dunkard group to the pennsylvanian permian boundary has long been debated fossil vertebrates from the dunkard group include paleoniscoids dipnoans a rhipidistian crossopterygian selachians lepospondyl and temnospondyl amphibians diadectomorphs primitive amniotes eureptiles and eupelycosaurs these vertebrates represent two biostratigraphically distinct assemblages one from the waynesburg and washington formations and the other from the overlying greene formation comparison of the dunkard vertebrate biostratigraphy to a vertebrate biostratigraphy and biochronology developed in new mexico texas allows correlation to the coyotean latest virgilian middle wolfcampian and seymouran late wolfcampian early leonardian land vertebrate faunachrons tetrapod taxa from the waynesburg and washington formations include edops and protorothyris coyotean index taxa as well as the characteristic coyotean taxa trimerorhachis diadectes edaphosaurus and dimetrodon significantly these dunkard taxa are best known from the archer city formation in texas which is late coyotean middle wolfcampian the greene formation contains the eupelycosaur ctenospondylus an index taxon of the seymouran land vertebrate faunachron dunkard xenacanth selachians support the tetrapod based correlations vertebrate biochronology thus indicates that the waynesburg and washington formations are late coyotean whereas the greene formation is seymouran therefore vertebrate biostratigraphy and biochronology indicate that the entire dunkard group is early permian and likely straddles the wolfcampian leonardian boundary

magnitude of crustal extension in the southern great basin strike slip faults in the southern great basin separate areas of cenozoic upper crustal extension from relatively stable tectonic blocks linear geologic features offset along the garlock fault las vegas valley shear zone and lake mead fault system allow reconstruction of the southern great basin to a pre extension configuration the sierra nevada mojave desert spring mountains and colorado plateau are treated as stable unextended blocks that have moved relative to each other in response to crustal extension with the spring mountains held fixed to the mojave block our reconstruction indicates a minimum of 65 extension 140 km between the southern sierra nevada and colorado plateau

cloud resolving modeling of tropical cloud systems during phase iii of gate part i two dimensional experiments abstract a formal framework is established for the way in which cloud resolving numerical models are used to investigate the role of precipitating cloud systems in climate and weather forecasting models emphasis is on models with periodic lateral boundary conditions that eliminate unrealistic numerically generated circulations caused by open boundary conditions in long term simulations defined in this formalism is the concept of large scale forcing and the cloud environment interactions that are consistent with the periodic boundary conditions two dimensional numerical simulations of the evolution of cloud systems during 1 7 september 1974 in phase iii of the global atmospheric research program atlantic tropical experiment gate are conducted based on the above formalism a simple technique is used to force an anelastic cloud resolving model with evolving large scale horizontal wind field and large scale forcing for the temperature and moisture obtained from the gate data the 7 day period selected i

mesoscale convective systems 1 mesoscale convective systems mcss have regions of both convective and stratiform precipitation and they develop mesoscale circulations as they mature the upward motion takes the form of a deep layer ascent drawn into the mcs in response to the latent heating and cooling in the convective region the ascending layer overturns as it rises but overall retains a coherent layer structure a middle level layer of inflow enters the stratiform region of the mcs from a direction determined by the large scale flow and descends in response to diabatic cooling at middle to low levels a middle level mesoscale convective vortex mcv develops in the stratiform region prolongs the mcs and may contribute to tropical cyclone development the propagation of an mcs may have a discrete component but may further be influenced by waves and disturbances generated both in response to the mcs and external to the mcs waves of a larger scale may affect the propagation velocity by phase locking with the mcs in a cooperative mode the horizontal scale of an mcs may be limited either by a balance between the formation rate of convective precipitation and dissipation of stratiform precipitation or by the rossby radius of the mcv the vertical redistribution of momentum by an mcs depends on the size of the stratiform region while the net vertical profile of heating of the large scale environment depends on the amount of stratiform rain regional variability of the stratiform rain from mcss affects the large scale circulation s response to mcs heating

a review of the stratigraphy and stratigraphic nomenclature of the dunkard group in west virginia and pennsylvania usa abstract dunkard group strata the youngest paleozoic rocks in the appalachian basin extend from the base or top of the waynesburg coal varying among neighboring state geological surveys to the highest exposures geologic investigation and mapping of the dunkard group began with the first pennsylvania geological survey in the 1830s but poor exposure exposure of only limited stratigraphic intervals and lack of significant economic commodities have hampered stratigraphic studies maximum thicknesses in excess of 335 m 1100 ft are found beneath the highest ridges along the synclinorium axis near wileyville west virginia and windy gap pennsylvania and the stratigraphic correlation of these sites is shown with composite sections constructed from core records and measured sections distinct facies provinces are documented in the dunkard group from south to north interpreted as 1 upper fluvial plain 2 lower fluvial plain and 3 fluvial lacustrine deltaic plain this spatial array of facies provinces is illustrated by a cross section through dunkard group and underlying monongahela group strata based on drillers and geologists core logs strata in the upper fluvial plain are cyclic sequences of red green and gray nonfissile mudstone and claystone paleosols exhibiting vertic features red green and gray fissile shale and gray and green sandstone coal and limestone are rare although abundant calcareous material is present as nodules and cement in contrast the fluvial lacustrine deltaic plain cycles are comprised of coal and nonmarine limestone fewer fluvial shale and sandstone units and only rare redbeds the lower fluvial plain cycles exhibit a transition between the other two provinces containing coal and nonmarine limestone as well as significant fluvial units and redbeds coal beds in the dunkard group are best developed in the fluvial lacustrine deltaic plain but are generally thin and low in quality stratigraphically extensive laterally continuous road cuts and numerous subsurface exploration records particularly long continuous cores targeting coal beds beneath the dunkard group now aid in better understanding the stratigraphy of the dunkard group and will aid in future investigations of these rocks

uniform sense normal simple shear of the continental lithosphere geophysical studies suggest that the thin crust characteristic of the basin and range province extends eastward beneath the west margin of the colorado plateau and rocky mountain regions in arizona and utah zones perhaps over 100 km wide may be defined bounded on the west by the east limit of upper crustal normal faults that account for more that 10 extension and on the east by the east limit of thinning beneath the colorado plateau a discrepancy exists within these zones between the negligible extension measurable in the upper crust and the substantial extension apparent from crustal thinning assuming the discrepant zone crust was as thick as or thicker than the colorado plateau rocky mountain crust prior to extensional tectonism if various theories appealing to crustal erosion are dismissed mass balance problems evident in the discrepant zones are most easily resolved by down to the east normal simple shear of the crust moving lower and middle crustal rocks that initially were within the zones up and to the west to where they now are locally exposed in the basin and range province west of the discrepant zones in both arizona and utah east directed extensional allochthons with large displacement are exposed these geophysical and geological observations complement one another if it is accepted that the entire crust in both arizona and utah failed during extension on gently east dipping east directed low angle normal faults and shear zones over a region several hundred kilometres wide large scale uniform sense normal simple shear of the crust suggests the entire lithosphere may do the same such a hypothesis predicts major lithospheric thinning without crustal thinning will occur in plateau areas in the direction of crustal shear in the case of the arizona utah and red sea extensional systems and possibly the death valley extensional terrain a broad topographic arch typically 1500 2000 m higher than the extended terrain is present suggesting lithospheric thinning in areas predicted by the hypothesis

tectonic and hydrologic controls on cyclic alluvial fan fluvial and lacustrine rift basin sedimentation jurassic lowermost cretaceous todos santos formation chiapas mexico abstract the nonmarine upper jurassic lowermost cretaceous todos santos formation of central chiapas mexico was deposited in half graben basins formed during the early rifting stage of the southern gulf of mexico basin this formation consists of alluvial fan fluvial and lacustrine sequences that were deposited under arid climatic conditions alluvial fans were built outwardly from the elongate basin margins by runoff that flowed transverse to the basin axis whereas fluvial units were deposited by rivers that flowed parallel to the basin axis lacustrine deposition took place in a topographic depression adjacent to the basin margin the presence of alluvial fan and fluvial or lacustrine deposits in vertically stacked cyclic megasequences hundreds of meters thick indicates that the basin opography changed through time this cyclicity denotes that periodically fluvial or lacustrine environments occupied the basin margin position and at other times alluvial fan sedimentation occurred there cyclicity was caused by periodic changes from high to low rates of basin subsidene the response of these three depositional environments to basin subsidence differed due to the unique hydrologic controls on sediment transport and deposition in each environment lakes were maintained by springs that emanated from the fractured fault margin and by fluvial discharge fluvial discharge and deposition resulted from precipitation or annual snowmelt anywhere in the river s expansive drainage basin whereas alluvial fan sedimentation occurred only when there was infrequent significant precipi ation in the small drainage basin from which fan sediment was derived as a result of these hydrologic controls the lacustrine or fluvial environments responded more quickly to periods of active tectonic subsidence and migrated over the fans to occupy the basin margin depression aided by a decrease in basin subsidence alluvial fans eventually prograded and displaced the fluvial or lacustrine environments away from the basin margin

mitigation of atmospheric phase delays in insar data with application to the eastern california shear zone we present a method for estimating radar phase delays due to propagation through the troposphere and the ionosphere based on the averaging of redundant interferograms that share a common scene estimated atmospheric contributions can then be subtracted from the radar interferograms to improve measurements of surface deformation inversions using synthetic data demonstrate that this procedure can considerably reduce scatter in the time series of the line of sight displacements we demonstrate the feasibility of this method by comparing the interferometric synthetic aperture radar insar time series derived from ers 1 2 and envisat data to continuous global positioning system data from eastern california we also present results from several sites in the eastern california shear zone where anomalous deformation has been reported by previous studies including the blackwater fault the hunter mountain fault and the coso geothermal plant

an overview and interpretation of autocyclic and allocyclic processes and the accumulation of strata during the pennsylvanian permian transition in the central appalachian basin usa abstract autocyclic and allocyclic processes controlled the lithostratigraphy of strata that accumulated in the central appalachian foreland basin during the pennsylvanian and the transition to the permian the transition strata from bottom to top include the late pennsylvanian pittsburgh and uniontown formations of the monongahela group the waynesburg and washington formations of the dunkard group and the permian greene formation of the dunkard variations in the amount of precipitation were the predominant allocyclic control on stratigraphic variations in terrestrial organic productivity lacustrine base levels basin scale weathering water table and pedogenesis sediment supply and sedimentary geochemistry tectonic subsidence controlled accommodation space and basin configuration eustasy had little or no effect on the stratigraphy of strata deposited in this continental basin during the pennsylvanian permian transition autocyclic processes were the predominant spatial control on architecture of alluvial plain aggradation paleosols delineating regional unconformities show a gradual upward transition from kaolinitic underclay paleosols indicative of a humid climate in the late pennsylvanian monongahela group to petrocalcic paleosols indicative of a dry subhumid to semiarid climate during deposition of dunkard strata as in the monongahela group the dunkard group waynesburg and washington formations contain multi bedded nonmarine lacustrine limestones with subareal exposure features these limestones grade laterally into petrocalcic paleo vertisols in the up dip alluvial plain subareal exposure features are uncommon in centimeter scale micritic limestones in the permian greene formation equivalent up dip paleosols have been lost to erosion coal bed continuity thickness and quality also decrease up section from the very thick m and laterally continuous pittsburgh coal at the base of the monongahela group to thin cm scale and laterally discontinuous coal beds that unconformably overlie the paleosol underclay limestone complexes in the greene formation lacustrine shales and impure wacke fluvio lacustrine sandstones commonly with a weak pedogenic overprint generally overlie coal beds during accumulation of monongahela and dunkard mdg strata within the basin center unconformities at the tops of regional paleosols overlain by lacustrine strata suggest allocyclic induced repeated rise and fall of lacustrine conditions in a lacustrine fan delta complex analogous to the okavango basin and fan in namibia southern africa and or the pantanal in southern brazil during maximum lake levels progradation of fluvio deltaic systems resulted in laminated shale conformably overlain by dark shale and flat bottomed distributary mouth bar siltstones and sandstones prograding distributaries and or fluvial channels subsequently incised the flat bottom mouth bar sands where basin margin strata are preserved south of the basin center depositional environments consist of aggrading alluvial plain sequences with paleosols fluvial channel sands and flood plain deposits anastomosing fluvial systems prograded across a low gradient 1 ft mile 20 cm km alluvial plain into the basin center a weak pedogenic overprint marked by ubiquitous root penetrations occurs throughout most basin centered fluvial deposits the subtle but continuous decline in the repetition of cyclic lithostratigraphy up section in the mdg particularly in the greene formation appears to be the result of a 10 myr climate transition from the humid to dry subhumid climate cycles of the late pennsylvanian to the equable semiarid to arid climate of the middle permian in north america cyclothems common in pennsylvanian strata become less distinct up section in the dunkard because of decreasing development of underclays coal and limestone this 30 myr period of transition from the humid pennsylvanian to the arid permian has been referred to as the dyassic period

callipterid peltasperms of the dunkard group central appalachian basin abstract the dunkard group is the youngest late paleozoic rock unit in the central appalachian basin its age however remains controversial in its southern and western two thirds the dunkard is comprised largely of red beds sandstone and siltstone channel deposits and paleosols in its thickest most northerly exposures in southwestern pennsylvania northern west virginia and east central ohio much of the lower part of the unit is composed of coals non marine limestones and gray often calcareous paleosols age dating is confounded by the non marine nature of the deposit and by the lack of dateable volcanic ash beds dunkard fossils include plants vertebrates and both aquatic and terrestrial invertebrates most of the fossil groups point to an age very close to if not including the pennsylvanian permian boundary though the exact position of that boundary is uncertain callipterids make their first appearance in the dunkard flora in the middle of the washington formation and continue into the greene formation but in different beds from those containing wetland floral elements publication of these plants in the permian flora of fontaine and white 1880 created an immediate controversy about the age of the unit because callipteris conferta now autunia conferta was at the time considered to be an index fossil for the base of the permian subsequent collecting has revealed these callipterds to comprise four species a conferta autunia naumannii lodevia oxydata and rhachiphyllum schenkii callipterids and the conifers with which they are sometimes associated are typically found in seasonally dry equatorial environments and most likely constitute an environmentally controlled biofacies this biofacies is not well known resulting in limited biostratigraphic utility

organized convection parameterization for the itcz abstractmesoscale convective systems mcss are of fundamental importance in the dynamics of the atmospheric circulation and the climate system they are often observed to develop over significant terrain in ambient shear flows in midlatitudes and embedded within the madden julian oscillation mjo and convectively coupled equatorial wave ccew envelopes as well as in the intertropical convergence zone itcz yet general circulation models gcms fail to resolve these systems and their underlying convective parameterizations are not directed to represent organized circulations shear parallel mcss which are common in the itcz have a three dimensional structure and as such present a serious modeling challenge here a previously developed multicloud model mcm is modified to parameterize mcss one of the main modifications is the parameterization of stratiform condensation to capture extended stratiform outflows which characterize mcss resulting from strong upper level jets linear analysis show

structures and dynamics of quasi 2d mesoscale convective systems abstract recently three distinct archetypes for midlatitude linear mesoscale convective systems mcss have been identified this article focuses on the fundamentals of two of these archetypes convective lines with trailing stratiform ts precipitation and convective lines with leading stratiform ls precipitation both the ts and ls modes typically exhibit quasi 2d reflectivity patterns and quasi 2d environmental storm relative wind fields ongoing work has revealed that there are three common flow structures for these quasi 2d mcss front fed ts systems which are sustained by front to rear storm relative inflow as well as front fed ls and rear fed ls systems which are sustained by rear to front storm relative inflow this paper summarizes the observed structures of the front fed ts front fed ls and rear fed ls modes and then outlines an idealized numerical experiment in which these modes were simulated the authors analyze the basic simulated kinematic and microphysical structures and provid

evolution of extensional basins and basin and range topography west of death valley california neogene extension in the death valley region se california has produced a variety of sedimentary basins diachronous movements on an array of strike slip and normal fault systems have resulted in the uplift and preservation of older basins in modern ranges one of the best exposed of these is the nova basin on the western flank of the panamint mountains the nova basin includes over 2000 m of sedimentary and volcanic rocks deposited during denudation of the panamint mountains metamorphic core complex in late miocene early pliocene time the principal growth structure for the basin was the emigrant detachment which initiated and moved at a low angle modern panamint valley west of the range developed as a consequence of late pliocene recent kinematically linked movement on the right slip high angle hunter mountain fault zone and the low angle panamint valley detachment detailed mapping of the intersection between the emigrant and panamint valley detachments demonstrates that segments of the earlier system remained active during development of panamint valley and thus during development of modern basin and range topography as well these results indicate that large scale extension in the death valley region accommodated by movement on low to moderate angle normal fault systems and high angle strike slip fault systems is a continuing process basin and range topography in the panamint valley death valley area was generated at least in part by displacements on low angle detachments rather than high angle normal faults

kinematic and thermodynamic characteristics of the flow over the western pacific warm pool during toga coare abstract rawinsonde and satellite infrared radiation ir data from the tropical ocean global atmosphere toga coupled ocean atmosphere response experiment coare are used to investigate mean and transient behavior and horizontal variability of the atmosphere over the western pacific warm pool infrared data for the 4 mo intensive observing period iop and vertical motion fields indicate that the intensity of convection height of maximum upward motion and sst all increased from west 140 e to east across the coare domain iop mean ir data show a double itcz intertropical convergence zone structure north and south of the intensive flux array ifa centered at 2 s 156 e although marked variability in the patterns occurred on a month to month basis three prominent westerly wind bursts occurred over the ifa during the 4 mo iop in association with the intraseasonal oscillations isos strong upward motion usually occurred 1 3 weeks prior to the peak low level westerlies subsidence dominated when

multicloud models for organized tropical convection enhanced congestus heating abstract despite the recent advances in supercomputing the current general circulation models gcms poorly represent the large scale variability associated with tropical convection multicloud model convective parameterizations based on three cloud types congestus deep and stratiform introduced recently by the authors have been revealed to be very useful in representing key features of organized convection and convectively coupled waves here a new systematic version of the multicloud models is developed with separate upper and lower troposphere basis functions for the congestus and stratiform clouds it naturally leads to a new convective closure for the multicloud models enhancing the congestus heating in order to better pinpoint the congestus preconditioning and moistening mechanisms the models are studied here for flows above the equator without rotation effects first the new model results consist of the usual synoptic scale convectively coupled moist gravity wave packets moving at 15 20 m

the early permian age of the dunkard group appalachian basin u s a based on spiloblattinid insect biostratigraphy abstract the dunkard group of the appalachian basin ohio pennsylvania west virginia is a 340 m thick sequence of primarily fluvial and lacustrine deposits that contain a diverse fossil record including a blattoid insect forewing identified as sysciophlebia balteata scudder this wing originates from the cassville shale in the waynesburg formation at the very base of the dunkard group s balteata is a zone species of a late paleozoic spiloblattinid insect zonation that is calibrated by the co occurrence of spiloblattinid zone species with conodont and fusulinid zone species in kasimovian to early asselian mixed marine continental profiles of new mexico usa and the donets basin in the ukraine as well as by the isotopic ages of volcanic intrusions into the late stephanian gzhelian strata of the saale basin in germany the base of the zone underlying the s balteata zone is defined by the fad of sysciophlebia ilfeldensis in the late gzhelian and has an upper limit lad of early to middle asselian an early or middle asselian to earliest sakmarian range of both the subzones of the s balteata zone can be inferred given that the mean duration of a spiloblattinid insect zone is about 1 5 to 2 ma the upper limit of the s balteata zone is early sakmarian hence the base of the dunkard group should be maximally of early asselian or minimally of earliest sakmarian age

the role of pre existing thrust faults and topography on the styles of extension in the gran sasso range central italy abstract structural analysis and field mapping together with simple geometrical and flexural elastic models document that two styles of quaternary extensional tectonics characterized the gran sasso range central apennines italy in the western part of the range extension took place on 10 15 km long range front normal faults with associated 600 1000 m high escarpments showing evidence of late glacial holocene activity this topography has been reproduced with a thin elastic plate subjected to the isostatic forces induced by the movement along high angle 55 65 planar normal faults in the eastern part of the belt extension occurred on shallow dipping normal faults 30 35 which reactivated progressively deeper pre existing thrusts in this area antithetic domino faults formed to accommodate the mechanical adjustment of the hanging wall over a variably dipping major fault surface the eastward increase in shortening due to the earlier compressional phase documented in the gran sasso belt by previous authors accounts for the more developed zones of weakness and high topographic relief in the eastern sector this setting could explain the different styles of extension and the more advanced northeastern limit of normal faulting in the eastern sector this work suggests that normal faults can originate either with low or high angle geometry in the upper crust according to the pre existing tectonic setting and that topography could be important in controlling the geometry and pattern of migrating normal faulting

momentum transport by a line of cumulonimbus abstract the vertical transport of horizontal momentum normal to a line of cumulonimbus observed during gate on 14 september 1974 is against the vertical momentum gradient contrary to the predictions of mixing length theory data from repeated aircraft passes normal to the line s axis at heights from 0 15 to 5 5 km are used to document the flux and determine its source the flux is concentrated in roughly a 25 km wide active zone just behind the leading edge of the line in kilometer scale convective updrafts accelerated upward by buoyancy and toward the rear of the line by mesoscale pressure forces the fall in mesoscale pressure from the leading edge to the rear of the active zone is mainly hydrostatic resulting from relatively high virtual temperatures and the 60 degree tilt of the leading edge from the vertical with the clouds at the surface well ahead of those aloft evaluation of the terms in the momentum flux generation equation confirms that the above process reflected by the velocity buoyan