geodynamics of lithosphere and earth s mantle seismic anisotropy as a record of the past and present dynamic processes plate tectonics has significantly broadened our view of the dynamics of continental evolution involving both the processes currently active at the surface and those extending deep into the interior of the earth seismic anisotropy provides some of the most diagnostic evidence for mapping past and present deformation of the entire crust mantle system

observations of the breakdown of mountain waves over the andes lidar observatory at cerro pachon on 8 9 july 2012

climatology of short period gravity waves observed over northern australia during the darwin area wave experiment dawex and their dominant source regions 1 the darwin area wave experiment dawex was designed to investigate the generation and propagation of gravity waves from intense regions of localized convection that occur regularly over northern australia in the vicinity of darwin during the premonsoon period this multinational program was conducted during the austral spring 2001 using a range of coordinated optical radar and in situ balloon measurements as part of this program all sky image observations of short period gravity wave events in the near infrared oh nightglow emission altitude 87 km were made from two well separated sites in northern australia wyndham 15 5 s 128 1 e and katherine 14 5 s 132 3 e over a 10 day period during november 2001 a total of 25 extensive wave events were observed during this period from which the dominant horizontal wave characteristics were determined to be wavelength 25 35 km and observed phase speed 27 75 m s yielding observed periods from 7 to 14 min consistent with previous measurements at other low latitude sites a key finding of this study was a marked anisotropy in the wave propagation headings with over 3 4 of the events exhibiting a strong southward component of motion and a clear preference for wave progression over the azimuthal range se to ssw although this range encompasses gravity waves originating locally from the darwin area the majority of the wave events exhibited propagation headings consistent with more distant sources located to the north and northwest of australia assuming deep convection was the dominant mechanism for the waves the strong asymmetry in their velocity distribution appears to result from a combination of nonuniformity in the geographic occurrence of thunderstorms coupled together with significant wind filtering effects at the source altitude and within the middle atmosphere these results are consistent with long range short period wave propagation most probably in the form of ducted waves possibly from intense convective regions located 1000 km to the north over the indonesian island chain

three field photometer observations of short period gravity wave intrinsic parameters in the 80 to 100 km height region 1 a three field photometer 3fp for making observations of airglow in the mesosphere lower thermosphere mlt region has been operated at the center of the large mf aerial array located near adelaide 138 e 35 s since 1993 observations of the 557 7 nm airglow intensity emitted by atomic oxygen oi at heights near 97 km and the 730 0 nm airglow intensity emitted by hydroxyl oh near 87 km have been made simultaneously with mf spaced antenna observations of wind velocities in the 80 100 km height region the 3fp measures the intensity of the 557 7 nm airglow in three fields separated by about 13 km at heights near 97 km and then the intensity of the 730 nm airglow in three fields separated by about 12 km at heights near 87 km on a 60 s cycle these data have been analyzed to yield gravity wave observed phase speeds and horizontal wavelengths simultaneous mf radar data have been analyzed to yield measurements of the neutral wind velocity in 2 km height steps in the 80 100 km height interval every 2 min and these have been used together with the observed wave parameters to calculate intrinsic gravity wave parameters this paper presents a very brief overview of the system the motivation for the work and preliminary analysis of the data from 1995 until 2000

a shear instability seeding mechanism for quasiperiodic radar echoes the quasiperiodic echoes with periods in the range of 1 10 minutes originally discovered at the middle and upper atmosphere mu radar in japan in the early 1990s are now known to be a common feature of midlatitude sporadic e a possible role of shear instabilities and the associated kelvin helmholtz structure in seeding the plasma instabilities that produce the radar echoes is suggested in this paper the proposed mechanism has the advantage that the seed structure is generated in situ as part of the same neutral wind structure that serves to initiate the generation of the sporadic e layer in addition the range of observed periods can easily be explained since the kelvin helmholtz structure is embedded in the shear flow and moves with the mean flow in the shear layer the period observed in the ground based frame is simply a product of the horizontal wavelength and the mean flow velocity at the center of the disturbance finally a typical feature of the radar observations has been that the quasiperiodic structure often ebbs and wanes in intensity over a period of 30 to perhaps 60 min recent simulations of unstable neutral shears show that the timescale for the build up and eventual restabilization of the shear flow is 30 40 min comparable to the timescale found in the observations

in situ observations of instabilities in the mesopause region using foil chaff technique during the waves in airglow structures experiment wave campaigns 1 in order to investigate the dynamics of the mesopause region foil chaff experiments were carried out successfully during the wave2000 and wave2004 campaigns at kagoshima japan in the wave2004 campaign the height profiles of the horizontal and vertical wind speeds were obtained the wind shear layers of 40 m s km were located around the altitudes of 89 and 95 km and the profile of the richardson number reveals the existence of dynamically unstable layers at about the same height region ripple observations using the all sky imagers also support the possibility of dynamical instabilities in the wave2000 campaign a prominent small scale feature around an altitude of 90 5 km appeared in both the horizontal and vertical chaff motions these results demonstrate that the foil chaff technique is a valuable tool for in situ observation of small scale turbulence features around the mesopause

seismic anisotropy and mantle creep in young orogens summary seismic anisotropy provides evidence for the physical state and tectonic evolution of the lithosphere we discuss the origin of anisotropy at various depths and relate it to tectonic stress geotherms and rheology the anisotropy of the uppermost mantle is controlled by the orthorhombic mineral olivine and may result from ductile deformation dynamic recrystallization or annealing anisotropy beneath young orogens has been measured for the seismic phase pn that propagates in the uppermost mantle this anisotropy is interpreted as being caused by deformation during the most recent thermotectonic event and thus provides information on the process of mountain building whereas tectonic stress and many structural features in the upper crust are usually orientated perpendicular to the structural axis of mountain belts pn anisotropy is aligned parallel to the structural axis we interpret this to indicate mountainparallel ductile i e creeping deformation in the uppermost mantle that is a consequence of mountain perpendicular compressive stresses the preferred orientation of the fast axes of some anisotropic minerals such as olivine is known to be in the creep direction a consequence of the anisotropy of strength and viscosity of orientated minerals in order to explain the anisotropy of the mantle beneath young orogens we extend the concept of crustal escape or extrusion tectonics to the uppermost mantle we present rheological model calculations to support this hypothesis mountain perpendicular horizontal stress determined in the upper crust and mountain parallel seismic anisotropy in the uppermost mantle require a zone of ductile decoupling in the middle or lower crust of young mountain belts examples for stress and mountain parallel pn anisotropy are given for tibet the alpine chains and young mountain ranges in the americas finally we suggest a simple model for initiating mountain parallel creep

airglow imager observations of atmospheric gravity waves at alice springs and adelaide australia during the darwin area wave experiment dawex 1 the darwin area wave experiment occurred in australia from october to december 2001 an objective was to characterize the atmospheric gravity wave field produced from intense convective activity that is routinely observed around darwin during november and december two airglow imagers were sited at adelaide and at alice springs each located over 1000 km south of darwin waves were observed at the mesopause region propagating predominantly toward the southeast with some going to the northwest but with none observed going from east to west the lack of waves propagating toward the west suggests some wind filtering mechanism below 80 km altitude waves observed over alice springs were analyzed in detail on three nights on 16 november they were seen propagating toward the northwest it is proposed that they were generated by dynamical events associated with a cutoff low pressure system present over southwest australia on 17 and 19 november the observations are consistent with wave generation by convective activity present in the darwin area thus as proposed by walterscheid et al 1999 and hecht et al 2001a the ducting of waves from distant sources is shown to be a viable explanation for the quasi monochromatic waves frequently observed in airglow observations walterscheid et al 1999 suggested that ducting of waves from the extensive region of deep cumulus convection over northern australia explained the strong poleward directionality seen in the summer months the present study suggests that propagation from northern australia is selective and ducted waves from this region may not be the primary source of waves over adelaide when convection is occurring over central australia

late pleistocene and early holocene rivers and wetlands in the bonneville basin of western north america abstract field investigations at dugway proving ground in western utah have produced new data on the chronology and human occupation of late pleistocene and early holocene lakes rivers and wetlands in the lake bonneville basin we have classified paleo river channels of these ages as gravel channels and sand channels gravel channels are straight to curved digitate and have abrupt bulbous ends they are composed of fine gravel and coarse sand and are topographically inverted i e they stand higher than the surrounding mudflats sand channels are younger and sand filled with well developed meander scroll morphology that is truncated by deflated mudflat surfaces gravel channels were formed by a river that originated as overflow from the sevier basin along the old river bed during the late regressive phases of lake bonneville after 12 500 and prior to 11 000 14c yr b p dated samples from sand channels and associated fluvial overbank and wetland deposits range in age from 11 000 to 8800 14c yr b p and are probably related to continued sevier basin overflow and to groundwater discharge paleoarchaic foragers occupied numerous sites on gravel channel landforms and adjacent to sand channels in the extensive early holocene wetland habitats reworking of tools and limited toolstone diversity is consistent with theoretical models suggesting paleoarchaic foragers in the old river bed delta were less mobile than elsewhere in the great basin

climate environment and humans in north america s great basin during the younger dryas 12 900 11 600 calendar years ago global climate change associated with the onset of the younger dryas chronozone affected different regions of the northern hemisphere in different ways in the great basin of western north america the effect was positive for human populations relatively cool temperatures causing effectively wetter conditions filled some pluvial basins with shallow but permanent lakes and other basins with wellwatered marshes or meadows vegetation communities dominated by sagebrush and grasses promoted healthy and diverse animal populations ten archaeological sites from the region have been dated to the younger dryas chronozone evidence from these sites indicates that paleoindians with skull shapes and mitochondrial dna similar to modern western north american indians occupied the region these early humans produced a material culture characterized predominantly by large stemmed bifacial points although one site contained a small fluted point curated tool forms and technological activities represented in analyzed lithic assemblages suggest a highly mobile settlement strategy and redundant short term occupations of sites indicate frequent and long distance residential moves across territories spanning distances of up to 400 km paleoindian subsistence pursuits focused on artiodactyls primarily mule deer bighorn sheep and pronghorn antelope leporids chiefly jackrabbits birds sage grouse and waterfowl insects grasshoppers and possibly fish easy to process plants like cactus pads were also eaten but small seeds do not seem to have been an important part of great basin human diets until long after the younger dryas closer to 9500 cal bp the great basin record contains no evidence for natural catastrophe at the onset of the chronozone instead the younger dryas appears to have been among the best of times for human foragers in this region of north america 2011 elsevier ltd and inqua

airglow imaging observations of small scale structures driven by convective instability in the upper mesosphere over tirunelveli 8 7 n 1 airglow imaging observations of broadband oh meinel band emissions made on the night of 20 january 2007 from the tropical indian site tirunelveli 8 7 n 77 8 e reveal large and small scale wave features that are aligned perpendicular to each other and that are associated with gravity wave dynamics the large scale waves were the signatures of propagating quasi monochromatic qm waves whereas the small scale features were identified to be ripples generated by convective instability in the mesosphere lower thermosphere mlt region the qm waves showed consistent propagation toward the northwest direction throughout the observation period of 4 5 hr whereas the ripples that manifested as short lived patches in the airglow images were transient and did not show any prominent phase propagation in addition to these well resolved structures in images we infer the presence of waves with relatively longer observed time periods compared with the observed time period of qm waves from the spectrum of the time series generated with zenith intensity values derived from the images from the complementary wind and temperature data obtained with co located mf radar and sounding of atmosphere with broad band emission radiometry on the thermosphere ionosphere mesosphere energetics and dynamics mission an attempt is made to understand the dynamic processes occurring in the vicinity of the mesopause during the night of 20 january 2007 the uniqueness of the present observations is that there were short lived ripple patches seen in various parts of the sky during the entire observation period of 4 5 hr the precipitation rates obtained by the tropical rainfall measuring mission satellite mission suggest that the deep convective activity occurring over the equatorial eastern indian ocean provided a plausible source mechanism for sustained generation of the waves observed over tirunelveli during this night

large scale trapping features from the great basin usa the significance of leadership and communal gatherings in ancient foraging societies in the great basin large scale trapping features designed to capture multiple artiodactyls include fences or drive lines and corrals with associated wings more than 100 of these features are known in the great basin an experimental project confirms that these features must have been built through group effort the marked concentration of large scale trapping features in western and eastern nevada may be explained by ecological factors such as the presence of migrating herds of ungulates nearby toolstone sources pinyon nuts and water the proliferation of large scale trapping feature planning and construction beginning ca 5000 to 6000 years ago is supported by studies of trap associated projectile points and rock art initial construction of traps may have been sparked by human population increases that created new challenges and encouraged the development of new sociological and ecological adaptations

velocity anisotropy and shear wave splitting in rocks from the mylonite belt along the insubric line ivrea zone italy velocity anisotropy and shear wave splitting has been measured up to 600 mpa on seventeen mylonitic samples from the mylonite belt along the insubric line the rocks which range from felsic to mafic in composition have experienced large ductile strain seismic anisotropy a and shear wave splitting delta vs is significantly pressure dependent velocity anisotropies of p and s waves range from 9 to 27 vp and 10 to 25 vs at 10 mpa and from 4 to 15 and 6 to 17 at 600 mpa respectively oriented microcracks in addition to preferred orientation of anisotropic rock forming minerals contribute largely to velocity anisotropy and shear wave splitting in the low pressure range at high pressure 600 mpa where most of the cracks are closed velocity anisotropy and shear wave splitting is dominated by preferred mineral orientation texture the experimental data at 600 mpa are in fairly good agreement with velocity calculations voigt averages based on volume percentages of major minerals the stiffness tensor of respective rock forming minerals and the measured crystallographic orientation texture related reflection coefficients rc at the protolith mylonite interfaces normal incidence no density change are 0 04 vp and 0 03 vs for extremely anisotropic mylonites a approximate 12 calculations of the variation of reflection coefficients due to velocity anisotropy of p waves in mylonites of different lithologies literature data included give 90 less than 0 1 66 less than 0 05 and 44 less than 0 03 these results suggest that the directional variation of wave velocities in anisotropic mylonites alone does not provide the impedance contrast necessary to give rise for strong seismic reflections

oldowan behavior and raw material transport perspectives from the kanjera formation the archaeological record of oldowan hominins represents a diverse behavioral system it has been suggested that exploitation of lithic resources by oldowan hominins was simplistic and represented mostly use of local sources of stone here we investigate the raw material selection and transport behaviors of oldowan hominins reflected in the stone artifact assemblages from the kanjera south formation south rachuonyo district kenya using geochemical methods ed xrf artifacts are linked to primary and secondary source outcrops throughout southwestern kenya these data show that hominins selected raw materials for transport at frequencies that are significantly different from their availability on ancient landscapes furthermore a substantial proportion of the assemblage represents transport over relatively long distances 10 km our study further suggests that in the early stages of stone tool use hominins used a wide variety of raw materials and selected these materials at some distance from their eventual discard locations early hominin behavior may have incorporated an understanding of raw material source distributions across a more extensive landscape than has been previously documented this supports the growing perspective that oldowan technology represents a more complex behavioral pattern than is usually associated with the beginnings of hominin tool use

lithospheric structure of tibet and western north america mechanisms of uplift and a comparative study we seek to determine the mantle lid thickness of the lithosphere and to constrain the mechanisms that are responsible for the cenozoic uplift of the tibetan plateau located behind the himalaya collision zone and the western united states located behind the san andreas transform convergent plate boundary selected first p arrivals of international seismological centre isc data at distances less than 22 are analyzed by the two station method to constrain the upper mantle structure of the basin and range br colorado plateau cp great plains gp and tibetan plateau tp the data are presented as plots of apparent velocity versus distance to the second station we show that these observations of apparent velocities versus distance as well as those that concern the attenuation of sn provide estimates of the mantle lid thicknesses we obtain the following mantle lid thicknesses br 20 40 km cp 35 50 km gp 150 195 km and tp 135 180 km sn is not observed for paths beneath the br and cp while sn efficiently propagates beneath the gp sn is also observed beneath most of tibet except in the north central part of the tp a possible interpretation of our observations is that indian continental lithosphere underthrusts only about the southern 2 3 of tibet

provenancing hornfels in the dingcun industry the exploitation of the vicinity source in this paper we attempt to determine the source of the hornfels used to make the famous late middle pleistocene lithic industry from dingcun in north china by combining geological mapping and geochemical fingerprinting xrf we demonstrate that the source of the hornfels was around the dagudui mountain 7 km east of dingcun taking into consideration the gujiao site which is also located along the fenhe river the palaeolithic inhabitants of the fenhe river drainage basin had a good knowledge of the local rock sources and used them over a very long period from the middle pleistocene to the neolithic our geochemical data not only helps us to establish the source of the dingcun industry but also provides a reliable basis for the sub classification of the hornfels that is more accurate than that resulting from visual inspection in addition our research initiates a new method for studying raw material sources of chinese paleolithic sites

characteristics of ripple structures revealed in oh airglow images small scale ripple structures observed in oh airglow images are most likely induced by either dynamic instability due to large wind shear or convective instability due to superadiabatic lapse rate using the data set taken in the mesopause region with an oh all sky imager at yucca ridge field station colorado 40 7 n 104 9 w from september 2003 to december 2005 we study the characteristics and seasonal variations of ripple structures by analyzing the simultaneous background wind and temperature observed by the nearby sodium temperature wind lidar at fort collins colorado 40 6 n 105 w and a nearby medium frequency radar at platteville colorado 40 2 n 105 8 w we are able to statistically study the possible relation between ripples and the background atmosphere conditions characteristics and seasonal variations of ripples are presented in detail in this study the occurrence frequency of ripples exhibits clear seasonal variability with peak in autumn the occurrence of ripples shows a local time dependence which is most likely associated with the solar tides the lifetime and spatial scale of these ripples are typically 5 20 min and 5 10 km respectively and most of the ripples move preferentially either southward or northward however more than half of the observed ripples do not advect with background flow they have higher richardson numbers than those ripples that advect with background flow it is possible that they are not instability features but wave structures that are hard to be distinguished from the real instability features

measuring prehistoric mobility strategies based on obsidian geochemical and technological signatures in the owens valley california we compare the organization of obsidian flaked stone technologies in two different time periods at ca iny 30 a village site in southern owens valley eastern california previous archaeological studies suggest a reorganization in settlement patterns between the newberry ca 3500e1500 bp and marana ca 650 contact periods from a highly mobile to a more residentially sedentary one new geochemical data based on laser ablation inductively coupled plasma mass spectrometry la icp ms analyses of obsidian artifacts associated with discrete house floors support this basic settlement model but reveal new detail in how people moved across the landscape and accessed extracted reduced and used obsidian resources in the earlier newberry period there is no relationship between flake size and distance to source and the falloff curve relating frequency of obsidian against distance is more gradual as expected but contrary to our expectations source diversity is not higher these factors suggest extremely high mobility but also selective extraction of particular sources newberry obsidian may have been acquired by groups of hunters who embedded quarrying within long distance trips to distant hunting grounds and subsequently transported bifacial cores to base camps by contrast marana patterns show strong relationships between flake size and distance from source and steeper fall off curves suggesting groups acquired their obsidian primarily from closer sources likely via exchange networks at the same time geochemical diversity especially among smaller resharpening flakes is higher in the marana period highlighting the wide ranging conveyance systems through which obsidian moved 2007 elsevier ltd all rights reserved

a quantitative approach to bedrock velocity resolution and precision the lithoprobe vancouver island experiment bedrock velocities obtained from the inversion of first break picks of multichannel seismic reflection data have been used to aid the interpretation of shallow reflectors the trade off between resolution and stability of inversion results has been examined models have been optimized by minimizing the variability of static corrections and a monte carlo method has been used to estimate their precision a velocity of 4 6 0 4 km s for the leech river complex lrc compares with velocities of 5 9 0 6 and 5 8 0 3 km s for the neighboring geological units velocity contrasts associated with the change in lithologies may therefore be a contributing factor for generating reflections from the faults that bound the lrc velocities of 5 5 0 4 and 4 6 0 6 km s on either side of the san juan fault suggest that an event identified on several shot gathers may be a reflection from a steeply dipping fault

concurrent oh imager and sodium temperature wind lidar observation of localized ripples over northern colorado 1 on 3 and 5 september 2002 the oh all sky imager at platteville colorado 40 2 n 104 7 w observed small scale wavelike patterns known as ripples with horizontal wavelengths of 9 km and 7 km and lifetimes of 9 min and 15 min respectively the colorado state university sodium lidar at nearby fort collins colorado 40 6 n 105 w also made concurrent observations of temperature and zonal and meridional winds which allowed us to determine the nature of the ripples observed our observations suggest that the 3 september ripple was induced by a convective instability located at 87 5 km and the 5 september ripple was induced by a dynamic instability at 88 5 km the ripples clearly advected as packets with the background wind lidar measurements also allowed us to relate the directions of wind shear to the phase front alignments of both the ripples and the nearby short period atmospheric gravity waves these spatial relationships provided a meaningful comparison with previously observed ripples as well as with current theoretical models using the 16 hour continuous lidar data set for each case we deduced that long period waves created an unusually large temperature perturbation at the ripple times on 3 september and an unusually large wind shear perturbation on 5 september these perturbations prepared the background atmosphere to be near the verge of local instability but as revealed again by lidar observation it was the superposition of smaller scale perturbations at the time of the ripples that helped to actually reach the conditions required for instability and generation of the ripples

paleoindian technological provisioning strategies in the northwestern great basin abstract great basin populations during the pleistocene holocene transition pht are often characterized as being mobile and focused on wetlands however the factors that influenced where paleoindians selected residential campsites are poorly understood using predictions derived from optimal foraging based patch choice models and gis reconstructions of the pht landscape some researchers have argued that occupations in smaller wetlands should have been shorter than occupations in larger wetlands but such arguments have rarely been evaluated using empirical data the pht lithic record provides an opportunity to evaluate the relationship between wetland size and occupation span by applying kuhn s 1995 concept of technological provisioning kuhn expects more mobile populations to provision individuals and more sedentary populations to provision places and suggests that 1 a strategy of provisioning individuals should be reflected by a high proportion of more extensively used artifacts made on non local raw materials and 2 a strategy of provisioning places should be reflected by a high proportion of less extensively used artifacts made on local raw materials we apply the technological provisioning concept to lithic assemblages from two of the parman localities extensive pht sites in the northwestern great basin and compare local and nonlocal artifacts to determine if paleoindians shifted from provisioning individuals while moving to from the sites to provisioning the place while occupying them there is no relationship between artifact transport distance and artifact use intensity we interpret these findings as evidence that paleoindians did not alter their provisioning strategies while occupying the parman localities likely because occupations were brief within a small wetland poorly suited to support groups for long periods

a global study of pn anisotropy beneath continents we apply a two station method of velocity determination to p n arrival times reported in the international seismological centre bulletin during the period 1964 1993 the azimuthal variation of these velocities provides evidence of p n anisotropy as large as 9 6 anisotropic regions are identified by examination of the azimuthal variation of the p n velocities within circular caps of radius 1 5 and 3 spaced at 1 intervals across the earth this procedure leads to 255 geographically distributed estimates of anisotropy the length scale over which the anisotropy varies indicates that uppermost mantle anisotropy beneath continents is controlled by regional orogenic strains and is inconsistent with a general interpretation in terms of plate scale mantle flow in addition the correlation between p n anisotropy and surficial tectonic features indicates that the anisotropy is primarily the result of the most recent deformation event we compare our p n anisotropy results fast directions and magnitudes with those of sks splitting studies to attempt to constrain the depth extent of the anisotropy this comparison suggests that in some areas where the fast directions agree sks splitting observations may arise from a layer beginning just below the moho whereas in others it must have a deeper origin in these areas the relative magnitudes of the measured anisotropy are consistent with a thin 100 150 km lithospheric layer of anisotropy

characteristics of short period wavelike features near 87 km altitude from airglow and lidar observations over maui 1 small scale less than 15 km horizontal wavelength wavelike structures known as ripples are a common occurrence in oh airglow images recent case studies attribute their origin to the presence of either convective or dynamical instabilities however little is known about their frequency of occurrence and period the maui malt observatory located at mt haleakala is instrumented with a na wind temperature lidar which allows the determination of whether the atmosphere is dynamically or convectively unstable and a fast oh airglow camera which takes images every 3 s with a sensitivity high enough to see the ripples this study reports on 2 months of observations in october november 2003 and in august 2004 eight nights of which also included na lidar measurements the imager results suggest that instability features occur in the 85 to 90 km region of the atmosphere for around 20 of the time the nominal observed period for the ripples is between 2 and 4 min while there are clear night to night variations the average observed period is similar for both the 2003 and 2004 observations in addition a few of the small scale structures are not ripples caused by instabilities but rather have features consistent with their being short horizontal wavelength evanescent waves their fractional intensity fluctuations are as large or larger than those of the ripple instabilities unlike the instabilities the origin of the evanescent waves is not determined

anisotropic upper mantle stratigraphy and architecture of the slave craton the earth s physical properties show a dominantly radial structure which is the result of compositional differentiation isochemical phase changes1 and rheological layering2 rheological layering is perhaps the most difficult to investigate using conventional seismological techniques because the seismic manifestation of this property elastic anisotropy may closely mimic the effects of isotropic heterogeneity3 nonetheless an improved characterization of earth s rheological structure promises important insights into such processes as plate dynamics and continental evolution here i present a methodology for effectively characterizing sharp transitions in anisotropic upper mantle structure using the coda of teleseismic p waves application to seismograms from the slave craton reveals a well developed stratigraphy at least in part anisotropic with major boundaries occurring at nominal depths of 75 135 and 195 km the geometry and sharpness of these discontinuities suggest a structural origin perhaps involving shallow subduction

deep structure of the southern apennines italy thin skinned or thick skinned 1 the deep structure of the southern apennines sa accretionary wedge is still debated since industrial seismic reflection and well data provide reliable constraints only to a depth of about 10 km as a consequence two directly linked questions regard 1 the shortening in the accretionary prism particularly within the buried apulian thrust units and 2 the degree of involvement of the lower plate basement i e the apulian crystalline basement to address these issues we have constructed a regional section along a recently released deep seismic reflection profile crop 04 which intersects the entire sa the resulting cross section adequately constrained to a depth of about 15 km has been framed in a geodynamic scenario characterized by the eastward roll back of the westward subducting apulo adriatic lithosphere on the basis of this section we speculate on the deep structure building both thin and thick skinned thrust models a cross check of these end members models against documented tectonic geophysical and geochemical features shows that the thin skinned model is generally more consistent with the available data the development of basement slices with thicknesses of tens of kilometers is unlikely while it remains possible that the apulian basement could have been involved with its upper few kilometers in the thin skinned model the total shortening of the allochthonous units i e apennine and apulian carbonate platforms and lagonegro basin is estimated to be greater than 280 300 km some 90 km of shortening can be attributed to the apulian thrust units

intrasource chemical variability of artefact quality obsidians from the casa diablo area california abstract obsidian from the casa diablo area of mono county california was an important source for artefacts and raw material in prehistoric california although little work has been devoted to investigating the potential geochemical variability within the many quarry areas it contains in this study 200 obsidian source samples from 20 collection locations in the casa diablo area were analysed by energy dispersive x ray fluorescence spectrometry laboratory analyses of solid flake and powdered obsidian samples are presented in quantitative measurement units parts per million and or weight percent composition calibrated to international rock standards the results of this research indicate that two possibly three geochemically distinct varieties of artefact calibre obsidian exist within the source area once believed by archaeologists to be a single geochemical entity these new findings carry implications for obsidian trade exchange systems studies in california and the great basin and for obsidian sourcing research in other areas of the world

multi technique geochemical characterization of the alca obsidian source peruvian andes we report results from comprehensive mapping and multi technique geochemical characterization of obsidian from the alca source in the peruvian andes 15 3 s 72 7 w aimed at understanding patterns of extraction and trade in one of the world s centers of complex civilization alca obsidian was among the most economically important and widely distributed volcanic glasses used for stone tool making in south america from ca 13 ka until recently yet the geologic source of this material has never been studied comprehensively our work establishes alca as one of the largest obsidian sources in south america and the only peruvian source known to have patterned intrasource geochemical variability there are six geochemically distinct alca subsources exposed from 2710 to 5165 m elevation over 330 km 2 of the highlands an area nearly seven times larger than previously known our results now permit provenance determination of artifacts to specific outcrops we analyzed 252 geologic samples using energy dispersive x ray fluorescence neutron activation analysis wavelength dispersive x ray fluorescence and nondestructive portable energy dispersive x ray fluorescence all techniques distinguish the same six alca subsources establishing analytical comparability between geochemical methods discrimination of alca obsidian to the subsource level using portable x ray fluorescence represents a major advance in nondestructive provenance analysis further nondestructive analysis of robust sets of obsidian artifacts within peru will allow high resolution study of the evolution of central andean exchange systems

maui mesosphere and lower thermosphere maui malt observations of the evolution of kelvin helmholtz billows formed near 86 km altitude 1 small scale less than 15 km horizontal wavelength structures known as ripples have been seen in oh airglow images for nearly 30 years the structures have been attributed to either convective or dynamical instabilities the latter are mainly due to large wind shears while the former are produced by superadiabatic temperature gradients dynamical instabilities produce kelvin helmholtz kh billows which have been known for many years however models and laboratory experiments suggest that these billows often spawn a secondary instability that is convective in nature while laboratory investigations see evidence of such structures the evolution of these instabilities in the atmosphere has not been well documented the maui mesosphere and lower thermosphere maui malt observatory located on mt haleakala is instrumented with a na wind temperature lidar that can detect dynamic or convective instabilities with 1 km vertical resolution over the altitude region from about 85 to 100 km the observatory also includes a fast oh airglow camera sensitive to emissions coming from approximately 82 to 92 km altitude which obtains images every 3 s at sufficient resolution and signal to noise to see the ripples on 15 july 2002 ripples were observed moving at an angle to their phase fronts after a few minutes structures appeared to form approximately perpendicular to the main ripple phase fronts the lidar data showed that a region of dynamical instability existed from approximately 85 5 to 87 km and that the direction of the wind shear in this region was consistent with the phase fronts of the ripple features the motion of the ripples themselves was consistent with the wind velocity at 85 9 km thus in this case the observed ripple motion was the advection of kh billows by the wind the perpendicular structures were seen to be associated with the kh billows they formed at the time when the atmosphere briefly became convectively unstable within the region where the kh billows most likely formed because of this and because the ripples were oriented approximately perpendicular to and moved with the billows we speculate that they are the secondary instabilities predicted by models of kh evolution the primary and perpendicular features were seen to decay into unstructured regions suggestive of turbulence while the formation and decay time appear consistent with models the horizontal wavelength of the perpendicular structures seems to be larger than models predict for the secondary instability features

simultaneous observations of the phase locked 2 day wave at adelaide cerro pachon and darwin the southern hemisphere summer 2 day wave tdw is the most dramatic large scale event of the upper mesosphere the winds accelerate over 1 week may attain 70 m s and are often accompanied by a near disappearance of the diurnal tide and stabilization of the period close to 48 h we denote this as the phase locked 2 day wave pl tdw we have examined airglow and meteor radar mr wind data from the andes lidar observatory cerro pachon chile 30 s 289 3 e mr data from darwin 12 5 s 131 e and airglow and medium frequency radar data from the university of adelaide 34 7 s 138 6 e for the behavior of the tdw during the austral summers of 2010 2012 and 2013 the cerro pachon and adelaide sites are located at similar latitudes separated in longitude by about 120 we find a remarkable coincidence between the tdw oscillations at chile and adelaide for the period january february 2010 the oscillations are nearly in phase in terms of local time and the minima and maxima repeat at nearly the same local time from cycle to cycle consistent with a phase locked wave number 3 tdw data for this and other years including darwin show that the amplitude of the diurnal tide decreases when the tdw is largest and that this occurs when the period is close to 48 h these observations support the proposal that the pl tdw is a subharmonic parametric instability wherein the diurnal tide transfers energy to a tdw that is resonant at nearly 48 h

synthesis of large high quality forsterite single crystals to 200 mm length and its significance 1 comprehensive and conclusive understanding of the anisotropic upper mantle relies on the physical property measurements on high quality homogeneous specimens of various crystallographic directions such specimens are ultimately prepared from one large single crystal large forsterite single crystals were synthesized for use in property measurements and laboratory experiments including anisotropic studies we are capable of producing large homogeneous single crystals over 50 mm diameter and 200 mm length

a gis model for predicting wetland habitat in the great basin at the pleistocene holocene transition and implications for paleoindian archaeology the great basin s earliest inhabitants relied heavily on wetland systems that underwent a great decline culminating in the early holocene in this paper we derive expectations for regional paleoindian archaeology by modeling the distribution and disappearance of lake margin wetland habitats basin geomorphology and hydrology are used to predict change through time in the occurrence of these habitats fifty two pluvial lakes are drained from their pleistocene highstands by computer simulation using gis and the changing extent of associated wetlands is quantified we find that as these lakes declined to shallow depths many experienced corresponding increases in wetland habitat prior to complete desiccation thus while the total area of wetland habitat in the region could have maintained some stability through this process the number of available basin wetlands would have dropped relatively rapidly as smaller basins completely dried up the model therefore implies that those lakes that disappeared earliest should hold the archaeological signatures most restricted to early paleoindian times assemblages associated with these lakes should also reflect higher forager mobility corresponding with the greater number of basin wetlands available we find preliminary support for the model in several archaeological cases but emphasize the need for further basin specific research to clarify the nature and timing of wetland habitat loss and the extent to which this was a constraint for paleoindian populations

mesosphere stratosphere troposphere radar observations of characteristics of lower atmospheric high frequency gravity waves passing through the tropical easterly jet 1 in this study we have examined the characteristics of high frequency gravity waves 5 50 min periodicity over a tropical region using the mesosphere stratosphere troposphere mst radar installed at gadanki 13 5 n 79 2 e india the mst radar 53 mhz was operated continuously for 15 5 h during 1700 0840 lt on 2 3 june 2005 during this period a strong unstable wind shear region existed above the tropical easterly jet at the height of tropopause this has provided an excellent opportunity to study the characteristics of internal atmospheric high frequency 15 40 min periodicity gravity waves generated in the boundary layer and passing through the shear layer the study reveals the generation of higher frequency 5 15 min periodicity gravity waves from this strong shear region and their vertical propagation both below up to a few kilometers and above the shear layer 0 5 km thick these waves showed upward propagation even above 20 km in the lower stratosphere indicating that unstable shear layers are the important source of momentum and energy fluxes that contribute significantly to the middle atmospheric dynamics in terms of gravity waves further a close association was also observed between the dissipating gravity waves and the distinctly enhanced signal to noise ratio and doppler spectral width of the mst radar echoes the present observation of radiation of high frequency gravity waves that propagate vertically upward from a strong wind shear region located immediately below a highly stratified layer is in accordance with the direct mechanism explained by nonlinear numerical simulation studies for the first time the present study illustrates the existence of layers of polarized refractive index structures in the heights of 10 15 km

seismic anisotropy and mantle flow seismic anisotropy in the mantle is primarily due to deformation induced lattice preferred orientation lpo of olivine crystals the aim of this paper is to better understand how such lpo is produced by flow and to learn whether observations of seismic anisotropy can be used to infer the local direction of flow within the mantle the basis of the work is a two dimensional theory which describes how lpo evolves during an arbitrary time dependent deformation ribe 1989 i investigate the evolution of lpo beneath ocean ridges above subducted slabs and in thermal convective flows the ocean ridge model predicts that the seismic anisotropy produced at a fast spreading ridge should be greater in magnitude than that produced at a slow spreading ridge and that the fast axis should be more nearly horizontal the subduction zone model predicts that strong seismic anisotropy should be produced above subducted slabs with the fast axis aligned with the slab regardless of the subduction angle the evolution of lpo in typical convective flows is extremely complex and depends strongly on such factors as the mode of heating and the surface boundary conditions in general there is no simple relation between the lpo and the local flow direction in any of the models considered the attempt to use seismic anisotropy to map flow patterns on a global scale is therefore probably unwarranted however the lpo does become aligned with the flow direction when the flow is a progressive simple shear such a flow occurs in limited portions of the mantle beneath the lithosphere at a fast spreading ridge above subducted slabs and in boundary layers beneath rigid surfaces such as continents observations of seismic anisotropy may therefore indicate the sense of shear at shallow depths in the mantle

are obsidian subsources meaningful units of analysis temporal and spatial patterning of subsources in the coso volcanic field southeastern california archaeologists frequently assign artifacts to chemically discrete subsignatures of major obsidian sources while the technical ability to do so has been demonstrated it remains to be shown that such information is behaviorally meaningful indeed some analysts choose not to make such determinations under the presumption that the data are not anthropologically relevant using a case study from the coso volcanic field which has at least four distinct subsignatures we examine this problem and conclude that subsource identification can be useful and quite interesting this is particularly so when large datasets encompassing spatially expansive areas can be assembled and statistically analyzed

through the high rock and beyond placing the last supper cave and parman paleoindian lithic assemblages into a regional context based on source provenance data derived from paleoindian artifacts in the great basin most researchers agree that early groups were mobile and far ranging however current explanations of the behavior reflected by those data differ some models portray paleoindians as residentially mobile foragers while others portray them as wetland tethered collectors reliant upon logistical forays we consider the types of hunter gatherer behavior that could produce trends in the x ray fluorescence data from three paleoindian assemblages in northwest nevada where abundant high quality obsidian essentially allows us to hold the effects of raw material availability constant between sites we conclude that while it is difficult to differentiate between residential and logistical mobility using technological and sourcing data alone we can nevertheless begin to understand the relative time averaged importance of particular locations on the landscape and why such places attracted paleoindians

obsidian hydration dating on the south coast of peru we compare over 230 obsidian hydration readings from 30 individual site components from the southern nasca region snr with independent age estimates based on radiocarbon dates and temporally diagnostic artifacts although there are problems with small sample sizes and readings must be adjusted for elevation a very strong relationship accounting for nearly 90 of the total variation in the data set is found this suggests that obsidian hydration dating ohd works in the snr and is a viable means of independently estimating age residual values from our regression suggest that hydration age estimates are usually within 15 of the radiocarbon estimates finally we present an equation other scholars can use to estimate age for quispisisa obsidian in the snr

nature of crustal reflectivity along the dekorp profiles in germany in comparison with reflection patterns from different tectonic units worldwide a review reflectivity of the continental crust displays many different patterns the dekorp lines are used as a basis for comparing and reviewing reflectivity in different tectonic units the brittle upper crust generally exhibits only two types of reflectivity it is either rather transparent preferably in some extensional provinces or and it shows traces of thrust and shear zones of former or present ruptures as these zones have a low impedance interior with few exceptions their first reflection onsets have a negative polarity and evince strong but short signals which sometimes can be correlated over several kilometers the generally ductile lower crust displays a completely different reflectivity in warm extensional and thin crusts the lower part is full of reflecting lamellae it is suggested that this type of reflectivity has a thermo rheological origin the creation of lamellae must take place in a ductile material with contrasting impedance under extensional stresses it can be associated with mineral alignment and corresponding seismic anisotropy destruction of lamellae may take place by a cooling process transforming parts of the lower crust into a brittle regime small stresses might deform or break the lamellae and leave a certain dispersed reflectivity like that in some old and cold shields there are no observations of reflecting lamellae in the upper crust or in the upper mantle in all areas the moho is the last reflecting band reflection moho which most often is identical with the classical refraction moho there are isolated mostly dipping reflections in the uppermost mantle in zones where the last tectonic event a delamination or subduction was not succeeded by a heating process the uppermost mantle is brittle again in most areas and may keep the memory of a cold collision over billions of years

characterization of exceptionally strong mesospheric wave events using all sky and zenith airglow observations 1 two unusually clear mesospheric gravity wave events were observed by the boston university all sky imager and the argentine airglow spectrometer on two consecutive nights at the el leoncito observatory argentina 31 8 s 69 3 w during august 2001 both events exhibited brightness amplitudes an order of magnitude above typical values the first event had the appearance of a large amplitude 60 in oh 6 2 22 in o 2 and 37 in o 1 s emissions peak to peak compared to 1 5 typically upward propagating gravity wave with pronounced nonlinear behavior the waves also showed noticeably curved wavefronts indicating that they had originated from a relatively small source region within 180 km of el leoncito estimates of the vertical flux of horizontal energy and momentum for the wave event in the oh and o 2 emissions were very large compared to typical values and they also indicated a high degree of flux divergence over the nominal 8 km altitude between the two layers the second event occurred on the following night and exhibited a frontal morphology and behavior consistent with an internal ducted gravity wave showing nonlinear behavior akin to a mesospheric bore the disturbance also had several interesting characteristics in particular the propagation speed decreased during its passage across the sky in addition a strong vertical temperature gradient due to the semidiurnal tide appeared to influence the occurrence of the bore event

the life cycle of instability features measured from the andes lidar observatory over cerro pachon on 24 march 2012 the aerospace corporation s nightglow imager ani observes nighttime oh emission near 1 6 m every 2 s over an approximate 73 field of view ani had previously been used to study instability features seen over maui here we describe observations of instabilities seen from 5 to 8 ut on 24 march 2012 over cerro pachon chile and compare them with previous results from maui with theory and with direct numerical simulations dns the atmosphere had reduced stability because of the large negative temperature gradients measured by a na lidar thus regions of dynamical and convective instabilities are expected to form depending on the value of the richardson number bright primary instabilities are formed with a horizontal wavelength near 9 km and showed the subsequent formation of secondary instabilities rarely seen over maui consistent with the primaries being dynamical instabilities the ratio of the primary to secondary horizontal wavelength was greater over chile than over maui after dissipation of the instabilities smaller scale features appeared with sizes in the buoyancy subrange between 1 5 and 6 km their size spectra were consistent with the model of weinstock 1978 if the turbulence is considered to be increasing the dns results produce secondary instabilities with sizes comparable to what is seen in the images although their spectra are somewhat steeper than is observed however the dns results also show that after the complete decay of the primary features scale sizes considerably smaller than 1 km are produced and these cannot be seen by the ani instrument

crustal volume balance during the india eurasia collision and altitude of the tibetan plateau a working hypothesis a working hypothesis is developed for the two stages of evolution of the tibetan plateau during the continental collision between india and eurasia the first phase was dominated by crustal shortening and thickening in what is now tibet while indochina was expelled southeastward away from eurasia at the end of this phase at 17 ma the estimated tibetan crustal thickness was 51 km the second phase has been dominated by thickening of tibet by the influx of crustal material from india with no associated crustal shortening the crustal thickening that is inferred to have occurred by this process is only feasible because leakage of crust from beneath the plateau is restricted by neighboring archean cratons that block lower crustal flow this leakage to the east and south from tibet to beneath yunnan is estimated as 20 30 of the influx at present but was much smaller at the start of this second phase of deformation it is suggested that at 11 ma the force exerted against the tibetan upper crust by this flowing material first exceeded the threshold that this brittle layer could resist and tibet began to extend eastward any satisfactory working hypothesis for the tibetan plateau must explain its dimensions its 17 ma ending of shortening and 11 ma start of extension and volcanism the eastward slip sense on its active normal and strike slip faults and the ratios of their displacements to present day slip rates which imply that their slip rates have gradually increased this working hypothesis accounts for these features and predicts a smooth and continuing increase in altitude

airglow observations of dynamical wind shear induced instabilities over adelaide australia associated with atmospheric gravity waves while several observations have been made in recent years of instability features in airglow images of atmospheric gravity waves agws such measurements are still rare to date these features are characterized by appearing to be aligned perpendicular to the agw wave fronts multi instrument observations confirm the theoretical prediction that such features are caused by convective instabilities where the agw induced temperature variation causes the total lapse rate to exceed the adiabatic lapse rate in february 2000 airglow observations were obtained at buckland park australia which showed instability features with a different characteristic these images showed small scale less than 10 km horizontal wavelength features aligned parallel to the larger scale agw wave fronts these features were only seen in oh images not in o2a images indicating that they originate below 90 km altitude simultaneous mf radar wind data reveal the presence of a mean wind shear which during the period of the small scale features was aligned nearly in the direction of agw propagation in addition the larger scale agw approached a critical level near 90 km altitude while the wind shear itself is not large enough to cause an instability an analysis of the data suggests that the small scale features are the result of a dynamic wind shear induced instability in the 87 90 km altitude region the instability was due to a combination of the background wind shear and the large shear induced by the passage of the larger scale agw as it approached the critical level