a new crater near insight implications for seismic impact detectability on mars a new 1 5 m diameter impact crater was discovered on mars only 40 km from the insight lander context camera images constrained its formation between 21 february and 6 april 2019 follow up high resolution imaging science experiment images resolved the crater during this time period three seismic events were identified in insight data we derive expected seismic signal characteristics and use them to evaluate each of the seismic events however none of them can definitively be associated with this source atmospheric perturbations are generally expected to be generated during impacts however in this case no signal could be identified as related to the known impact using scaling relationships based on the terrestrial and lunar analogs and numerical modeling we predict the amplitude peak frequency and duration of the seismic signal that would have emanated from this impact the predicted amplitude falls near the lowest levels of the measured seismometer noise for the predicted frequency hence it is not surprising this impact event was not positively identified in the seismic data finding this crater was a lucky event as its formation this close to insight has a probability of only 0 2 and the odds of capturing it in before and after images are extremely low we revisit impact seismic discriminators in light of real experience with a seismometer on the martian surface using measured noise of the instrument we revise our previous prediction of seismic impact detections downward from a few to tens to just 2 per earth year still with an order of magnitude uncertainty

an example of an accretionary forearc basin from northern central anatolia and its implications for the history of subduction of neo tethys in turkey deformed sedimentary sequences of late cretaceous middle eocene age located between the sakarya continent and the anatolian complex have been interpreted as the fill of a forearc basin the history and structure of this basin are critical for understanding the evolution of the neo tethyan subduction in the middle east i test and elaborate upon this interpretation on the basis of three basic outcrop areas of upper cretaceous lower tertiary sedimentary sequences confined to a northeast southwest trending belt in north west ankara these are the alci kinik and orhaniye areas they expose two different sedimentary sequences called alci and orhaniye in the alci area the sequence starts at the base with the continental red clastic rocks on the erosional surface of an underlying ophiolitic melange and continues upward into the shallow marine reefal buildup of the late maastrichtian age the upper half of the alci sequence is separated from its lower half by a local disconformity and dominated by the continental debris flow deposits composed mostly of volcanic material by contrast both the kinik and orhaniye areas are characterized by a thick continuous and coarsening upward sequence overlying conformably the underlying ophiolitic melange the lower half of the orhaniye sequence is dominated by a deep marine flysch its middle part by continental clastic material and the topmost part by the shallow marine reefal buildup lower contact relationships lithologic composition facies distribution internal structures and the regional tectonic settings of both sequences strongly suggest that the above mentioned three outcrops preserve the remnants of a peripheral accretionary forearc basin forming the north northwestern margin of the haymana polath accretionary forearc basin during middle campanian middle eocene time this peripheral basin is here named orhaniye accretionary forearc basin

geophysical observations of phobos transits by insight since landing on mars the nasa insight lander has witnessed 8 phobos and one deimos transit all transits could be observed by a drop in the solar array current and the surface temperature but mo

on deck seismology lessons from insight for future planetary seismology before deploying to the surface of mars the short period sp seismometer of the insight mission operated on deck for a total of 48 hr this data set can be used to understand how deck mounted seismometers can be used in future landed missions to mars europa and other planetary bodies while operating on deck the sp seismometer showed signals comparable to the viking 2 seismometer near 3 hz where the sensitivity of the viking instrument peaked wind sensitivity showed similar patterns to the viking instrument although amplitudes on insight were 80 larger for a given wind velocity however during the low wind evening hours the instrument noise levels at frequencies between 0 1 and 1 hz were comparable to quiet stations on earth although deployment to the surface below the wind and thermal shield lowered installation noise by roughly 40 db in acceleration power with the observed noise levels and estimated seismicity rates for mars detection probability for quakes for a deck mounted instrument is low enough that up to years of on deck recordings may be necessary to observe an event because the noise is dominated by wind acting on the lander though deck mounted seismometers may be more practical for deployment on airless bodies and it is important to evaluate the seismicity of the target body and the specific design of the lander detection probabilities for operation on europa reach over 99 for some proposed seismicity models for a similar duration of operation if noise levels are comparable to low wind time periods on mars

onset of maikop sedimentation and cessation of eocene arc volcanism in the talysh mountains azerbaijan the maikop series forms an important source rock in the former paratethys deposition is often interpreted as anoxic linked to restriction of the paratethys the pirembel formation in the talysh mountains azerbaijan is attributed to the maikop series and was deposited above the eocene volcanic peshtasar formation dating the onset of anoxia could help to distinguish glacio eustatic from tectonic causes of restriction we integrated magnetostratigraphy and biostratigraphy to date the onset of pirembel sedimentation and used geochemistry to characterize the tectonic setting of the peshtasar volcanic rocks the onset of maikop sedimentation in the talysh was determined to be 37 7 ma ruling out a link with the major sea level drop at the eocene oligocene transition 33 9 ma and favouring a tectonic cause extrapolating the average sedimentation rate 34 cm kyr suggests that the entire pirembel formation belongs to the late eocene we hypothesize that the end of volcanism is important in the transition to pirembel sedimentation the palaeomagnetic and geochemistry results for the volcanic rocks cluster in three groups suggesting three distinct episodes of volcanism volcanic sills within the eocene arkevan formation plot exactly on these groups confirming the relationship between the arkevan and peshtasar formations volcanic rocks of the talysh show continental arc signatures and may be related to an eocene volcanic belt extending towards southeastern iran

the seismicity of mars the insight interior exploration using seismic investigations geodesy and heat transport mission landed in elysium planitia on mars on 26 november 2018 and fully deployed its seismometer by the end of february 2019 the mission aims to detect characterize and locate seismic activity on mars and to further constrain the internal structure composition and dynamics of the planet here we present seismometer data recorded until 30 september 2019 which reveal that mars is seismically active we identify 174 marsquakes comprising two distinct populations 150 small magnitude high frequency events with waves propagating at crustal depths and 24 low frequency subcrustal events of magnitude mw 3 4 with waves propagating at various depths in the mantle these marsquakes have spectral characteristics similar to the seismicity observed on the earth and moon we determine that two of the largest detected marsquakes were located near the cerberus fossae fracture system from the recorded seismicity we constrain attenuation in the crust and mantle and find indications of a potential low s wave velocity layer in the upper mantle mars is seismically active 24 subcrustal magnitude 3 4 marsquakes and 150 smaller events have been identified up to 30 september 2019 by an analysis of seismometer data from the insight lander

a seismic model of the lunar mantle and constraints on temperature and mineralogy abstract we determine seismic profiles of the moon s interior using travel times obtained from a re analysis of the apollo data due to the limited number of quakes and stations travel times errors were determined and used in the inversions our model has a mean crustal thickness of about 30 km in the region of the apollo network with a 10 km zone of brecciation below the crust mean values of seismic velocities in the upper mantle are rather well constrained and are in the range 7 6 7 8 and 4 35 4 45 km s 1 for p and s waves respectively velocity variations in the middle mantle are less well defined in the zone of deep moonquakes below 740 km depth velocities increase slightly to 8 15 0 23 and 4 5 0 10 km s 1 for p and s waves respectively we analyse the seismic profile in term of mineralogy and temperature constraints our preferred models are a pyroxenite model for the upper mantle and a magnesian rich model for the lower mantle with increasing mg with depth we find temperatures of about 1100 k elastic lithosphere limit and 1500 k thermal lithosphere limit for radii of about 1400 and 1000 km respectively and show that the lunar mantle is probably depleted in th and u by at least 70 compared to an earth reference value of 25 7 ppb u for a crustal thickness of 40 km with a mean 1010 ppb th concentration we then find bulk th and u abundances comparable to and possibly lower than currently accepted terrestrial values

mineralogy petrography and whole rock geochemistry of the tertiary granitic intrusions in the eastern pontides turkey abstract granitic intrusions in eocene and post eocene volcanic rocks outcrop in the northern and southern zones of the eastern pontides ne turkey intrusions in the northern zone extend nw se whereas those in the southern zone are nearly e w orientated the contacts of the intrusions with the volcanic rocks are sharp epidotized and include volcanic xenoliths the margins of southern zone intrusions often contain abundant angular mafic microgranular enclaves of diorite to quartz diorite composition the rocks also show evidence of mingling and mixing between coeval mafic and felsic magmas field observations suggest a stopping type of ascent and emplacement style for the intrusions petrographically intrusions show variations in both colour and mineralogy with fine to medium granular monzonitic poikilitic rapakivi anti rapakivi and graphic textures based on modal mineralogy the northern rocks are monzonite quartz monzonite monzodiorite and quartz monzodiorite whereas the southern samples are monzogranite and granodiorite the rocks are generally calc alkaline to mildly alkaline transitional and metaluminous and show a cafemic trend the northern zone intrusions form a post collisional a type alkaline monzonitic association and southern zone intrusions form a post collisional i type granodioritic calc alkaline transitional association whole rock compositional data indicate that differentiation occurred via fractional crystallisation with or without magma mixing incompatible and rare earth element patterns indicate that both the northern and the southern zone intrusions were derived from melting of a mantle region enriched by subduction related fluids but evolved differently during ascent and emplacement u pb zircon dating in the southern zone yields an intrusion age of 44 4 0 3 ma regional geodynamics indicates post collisional extensional tectonics in the region crustal involvement and the level of emplacement may have been important for magmatic evolution especially for the southern zone intrusions after the cessation of subduction and subsequent crustal thickening

assessment of insight landing site predictions comprehensive analysis of remote sensing data used to select the interior exploration using seismic investigations geodesy and heat transport insight landing site correctly predicted the atmospheric temperature and pressure profile during entry and descent the safe landing surface and the geologic setting of the site the smooth plains upon which the insight landing site is located were accurately predicted to be generally similar to the mars exploration rover spirit landing site with relatively low rock abundance low slopes and a moderately dusty surface with a 3 10 m impact fragmented regolith over hesperian to early amazonian basaltic lava flows the deceleration profile and surface pressure encountered by the spacecraft during entry descent and landing compared well within 1 of the envelope of modeled temperature profiles and the expected surface pressure orbital estimates of thermal inertia are similar to surface radiometer measurements and materials at the surface are dominated by poorly consolidated sand as expected thin coatings of bright atmospheric dust on the surface were as indicated by orbital albedo and dust cover index measurements orbital estimates of rock abundance from shadow measurements in high resolution images and thermal differencing indicated very low rock abundance and surface counts show 1 4 area covered by rocks slopes at 100 to 5 m length scale measured from orbital topographic and radar data correctly indicated a surface comparably smooth and flat as the two smoothest landing sites opportunity and phoenix thermal inertia and radar data indicated the surface would be load bearing as found

a late pleistocene holocene lacustrine record from lake manas zunggar northern xinjiang western china information on the late quaternary palaeoclimate in the zunggar desert northern xinjiang is deduced from the study of three 5 m long cores taken from lake manas analyses including the mineralogical composition of bulk sediments stable isotope contents of carbonates organic matter pollen and diatoms were performed to help reconstruct the environmental evolution of the area the chronology is provided by 9 ams 14c dates done on carbonates or organic matter the record suggests a late pleistocene humid episode radiocarbon dated at 37 000 32 000 yr b p this episode is followed by a period of extreme aridity attributed to the last glacial maximum the early mid holocene record indicates conditions generally wetter than today as previously established for western china however our results show that the holocene period is rather complex after a minor wet warm pulse estimated to be around 12 000 yr b p the most important environmental change is recorded at 10 000 yr b p it led to the establishment of a steppic vegetation cover in the catchment and of a permanent lake which lasted 4000 years fluvial sedimentation took place between about 6000 and 4500 yr b p and it coincided with a decrease in moisture availability for vegetation growth a second lacustrine episode is recorded from about 4500 to 2500 yr b p although the pollen record and a sudden influx in detrital organic matter suggest a short term dry event around 3800 3500 yr b p the last 2500 years show climate unstability and the step wise establishment of hypersaline conditions in lake manas the major post glacial environmental changes appear to be roughly in phase with those observed in tibet

slow senonian and fast palaeocene early eocene uplift of the granitoids in the central eastern pontides turkey apatite fission track results abstract dating and forward modelling of the fission track data of apatite samples from the dereli ebinkarahisar region south of giresun in the eastern turkish pontides provides quantitative data on the regional tectonics resulting from the closure of neo thetys and the collision of eurasia and gondwana the age vs elevation profiles identified senonian 80 7 3 2 to 62 4 2 5 ma slow uplift and denudation interpreted as the result of the diapiric ascent of subduction related plutons above the neo tethyan subduction zone beneath the eurasian continent this was followed by rapid differential uplift during the palaeocene early eocene 57 4 2 4 to 47 8 2 4 ma which juxtaposed granitoid units of different ages compositions and emplacement levels in the crust and is thought to be related to the collision between the pontide eurasian and anatolide gondwana basements the modelling results must be interpreted with caution but appear to indicate a period of mio pliocene ca 5 ma reheating related to volcanism associated with the westward escape of the anatolian plate and uplift from the pliocene ca 3 5 ma up to the present

ophiolites as indicators of the geodynamic evolution of the tethyan ocean abstract reviewing the ophiolites of the alpine chain from the western mediterranean to the indian ocean we subdivide them into ten groups of outcrops the geological environment through time the internal composition and history are given for each emphasis is put on the variegated and successive geodynamic processes which can be reconstructed for the different ophiolitic belts since their birth as an ocean like crust to their incorporation through accretion to a continent one can distinguish low versus high tholeiitic partial melting fairly or poorly established ridges simple ridge type crust versus complex ridge ensimatic arc and even more complex type long lived versus short lived oceanic crust stages abrupt large scale pure obduction versus progressive collision related obduction or simple progressive juxtaposition to continent the major events through time in the tethyan ophiolitic belts can be listed as follows spreading ridge activity during the jurassic liguria dinaro hellenides lesser caucasus and the cretaceous peri arabic nain sabzewar with a jump of ridge in between repeated change from ridge to ensimatic arc dinaro hellenic lesser caucasus peri arabic west indian during the latest jurassic and cretaceous upper cretaceous tertiary collision related obductions pontic lesser caucasus liguria squeezing out the elevated portions of these basins lack of oceanic magmatism during the cenozoic but progressive accretion along accretionary wedges of the elevated portions of the remaining mesozoic crust van nain sabzewar zahedan mekran

understanding the seismic velocity structure of campi flegrei caldera italy from the laboratory to the field scale we report laboratory measurements of p and s wave velocities on samples of tuff from campi flegrei italy and a new tomographic velocity map of the campi flegrei caldera laboratory measurements were made in a hydrostatic pressure vessel during both increasing and decreasing effective pressure cycles selected samples were also thermally stressed at temperatures up to 600 c to induce thermal crack damage acoustic emission output was recorded throughout each thermal stressing experiment and velocities were measured after thermal stressing laboratory p and s wave velocities are initially low for the tuff which has an initial porosity of 45 but both increase by between 25 and 50 over the effective pressure range of 5 to 80 mpa corresponding to a decrease of porosity of 70 marked velocity hysteresis due to inelastic damage processes is also observed in samples subjected to a pressurization depressurization cycle tomographic seismic velocity distributions obtained from field recordings are in general agreement with the laboratory measurements integration of the laboratory ultrasonic and seismic tomography data indicates that the tuffs of the campi flegrei caldera can be water or gas saturated and shows that inelastic pore collapse and cracking produced by mechanical and thermal stress can significantly change the velocity properties of campi flegrei tuffs at depth these changes need to be taken into account in accurately interpreting the crustal structure from tomographic data

upper mantle s wave velocity structure of the east anatolian caucasus region geodynamic processes occurring in the upper mantle such as slab break off and lithosphere delamination often result in high rates of lithospheric deformation and rapid tectonic uplift of large areas the continent continent collision zone between arabia and eurasia has been widely studied in this context but several different viable geodynamic models exist to explain the uplift and deformation of the anatolian plateau and the caucasus mountains we have imaged the uppermost mantle shear wave velocity structure of the east anatolian caucasus region using surface wave tomography to better understand the regional tectonic activity since the onset of the collision between the arabian and eurasian plates furthermore we used our tomographic models to better understand the processes which are responsible for the formation of the 2 km high plateau and the widespread volcanism in eastern turkey as well as reactivation of deformation and deep seismicity in the eastern greater caucasus our model of regional upper mantle shear wave velocity structure supports subduction of the northern and southern branches of neo tethys lithosphere between eurasia and gondwana and suggests a possible underthrusting of the kura basin lithosphere beneath the greater caucasus

constraints on the shallow elastic and anelastic structure of mars from insight seismic data mars s seismic activity and noise have been monitored since january 2019 by the seismometer of the insight interior exploration using seismic investigations geodesy and heat transport lander at night mars is extremely quiet seismic noise is about 500 times lower than earth s microseismic noise at periods between 4 s and 30 s the recorded seismic noise increases during the day due to ground deformations induced by convective atmospheric vortices and ground transferred wind generated lander noise here we constrain properties of the crust beneath insight using signals from atmospheric vortices and from the hammering of insight s heat flow and physical properties hp3 instrument as well as the three largest marsquakes detected as of september 2019 from receiver function analysis we infer that the uppermost 8 11 km of the crust is highly altered and or fractured we measure the crustal diffusivity and intrinsic attenuation using multiscattering analysis and find that seismic attenuation is about three times larger than on the moon which suggests that the crust contains small amounts of volatiles the crust beneath the insight lander on mars is altered or fractured to 8 11 km depth and may bear volatiles according to an analysis of seismic noise and wave scattering recorded by insight s seismometer

pressure effects on the seis insight instrument improvement of seismic records and characterization of long period atmospheric waves from ground displacements mars atmospheric pressure variations induce ground displacements through elastic deformations the various sensors of the insight mission were designed in order to be able to understand and correct for these ground deformations induced by atmospheric effects particular efforts were made on one hand to avoid direct pressure and wind effects on the seismometer and on the other hand to have a high performance pressure sensor operating in the same frequency range as the seismometer as a consequence of these technical achievements and the low background seismic noise of mars the insight mission is opening a new science domain in which the ground displacements can be used to perform atmospheric science this study presents an analysis of pressure and seismic signals and the relations between them after a short description of the pressure and seismic sensors we present an analysis of these signals as a function of local time at the insight location then the coherent signals recorded by both pressure and seismic sensors are described and interpreted in terms of atmospheric signals and ground deformation processes two different methods to remove the pressure effects recorded by seis sensors are presented and their efficiency is estimated and compared these decorrelation methods allow the pressure generated noise to be reduced by a factor of two during the active day time period finally an analysis of seis signals induced by gravity waves demonstrates the interest of ground displacement measurements to characterize their arrival azimuth

post collisional adakite like magmatism in the agvanis massif and implications for the evolution of the eocene magmatism in the eastern pontides ne turkey abstract in the anatolia the caucasus and northwest iran the eocene epoch is characterized by widespread basic to acidic magmatism whose temporal and spatial evolutions and origin are poorly understood in this paper we provide geochronological and geochemical data on a suite of early eocene intrusions from northeast turkey and discuss their origin within a regional tectonic framework post to late collisional moderate to small bodies of quartz diorite and leucogranodiorite as well as later dacite porphyries intrude permo triassic low grade metamorphic rocks in the southern part of the eastern pontides very close to the neo tethyan izmir ankara erzincan suture in places the intrusives display well developed subsolidus foliations indicating on going penetrative deformation during and shortly after emplacement different emplacement depths were inferred based on the contact metamorphic mineral assemblages al in hornblende barometry and igneous textures quartz diorite 14 16 km vs dacitic porphyries 7 km biotite and hornblende ar ar and zircon u pb data indicate that the compositionally and texturally different intrusives were emplaced at 51 ma ypresian three lines of evidence indicate that the early eocene represents a tectonically active time with high exhumation rates 0 6 cm a 1 i the quartz diorite and dacitic porphyries were emplaced at different crustal depths ii the emplacement ages of these texturally distinct intrusive rocks are geochronologically undistinguishable and iii intrusive rocks locally show a well developed foliation the intrusive rocks display high abundances of al 2 o 3 sr ba lrees and low abundances of y sc and hrees and are similar to high silica adakites from supra subduction zone settings the geochemical features imply a residual and or fractionating assemblage rich in hornblende garnet pyroxene and poor in plagioclase all rock types display similar sr nd isotopic characteristics with initial e nd and 87 sr 86 sr values ranging from 1 0 to 1 1 and from 0 70421 to 0 70494 respectively these three coeval rock groups quartz diorite leucogranodiorite and dacite porphyries were generated from a similar source by variable degrees of partial melting and fractionation these data together with those from the literature clearly reveal that the adakitic signature is common in paleocene to early eocene igneous rocks in northern turkey on both sides of the izmir ankara erzincan suture but disappears towards the middle eocene regional geological constraints indicate that the continental collision between the pontides and the anatolide tauride block occurred in the paleocene and that the middle eocene represents a period of major extension characterized by a marine transgression we therefore suggest that the early eocene adakitic magmatism in northern turkey resulted from the presence of a thickened continental crust following the continental collision along the neo tethyan izmir ankara erzincan suture whereas the voluminous middle eocene magmatism was related to extensional collapse of a thickened orogen

monitoring of dust devil tracks around the insight landing site mars and comparison with in situ atmospheric data the nasa insight mission on mars is a unique opportunity to study atmospheric processes both from orbit and in situ observations we use post landing high resolution satellite images to monitor dust devil activity during the first 8 months of the mission we perform mapping and semiautomatic detection of newly formed dust devil tracks and analyze their characteristics sizes azimuths distances and directions of motion we find a large number of tracks appearing shortly after landing followed by a significant decrease of activity during late winter then a progressive increase during early spring new tracks are characterized by dark linear to slightly curvilinear traces ranging from a few to more than 10 m wide tracks are oriented in the ambient wind direction according to measurements made by insight s meteorological sensors the systematic analysis of dust devil tracks is useful to have a better understanding of atmospheric and aeolian activity around insight

review of the neotectonics of the eastern turkish armenian plateau by geomorphic analysis of digital elevation model imagery digital elevation model dem images provide synoptic views of the earth s surface allowing the analysis of landforms of still active tectonic and volcanic structures at regional scale a dem at 250 m pixel size constitutes regional scale data particularly efficient to investigate the late miocene quaternary deformation of the eastern turkish armenian plateau in the arabian eurasian area of convergence geomorphic analysis of the dem image associated with review of fault plane solutions of earthquakes show that faults are mostly strike slip with small vertical component here we show that the orientations of the tectonic and volcanic structures fit with a tectonic regime characterized by n s shortening and e w lengthening consistent with westward escape of anatolia perpendicular to the direction of the arabia eurasia shortening the uniform uplift of the plateau the predominance of strike slip faulting the lack of major thrusts and the occurrence of normal faults do not support a model of going on crustal thickening due to intracontinental convergence on the contrary our observations can be better interpreted in terms of lithospheric thinning and mantle upwelling related to gravity escape of anatolia

spatial and temporal evolution of rifting and continental breakup in the eastern black sea basin revealed by long offset seismic reflection data the age and distribution of the syn rift and early post rift infill records the spatial and temporal distribution of extension and breakup processes in a rift basin the eastern black sea basin ebsb is thought to have formed by back arc extension during cretaceous to early cenozoic time however a lack of direct constraints on its deep stratigraphy leaves uncertainties over the time duration and location for rifting and breakup processes in the basin here we use the enhanced imaging provided by 2d long offset seismic reflection profiles to analyze the deep structural and stratigraphic elements of the ebsb based on these elements we infer the presence of two distinct late cretaceous syn rift units recording initial extension rift stage 1 over the continental highs shatsky ridge and the mid black sea high followed by strain localization along the major basin bounding faults and rift migration towards the basin axis rift stage 2 overlying these units palaeocene eocene and oligocene units show a syn kinematic character in the nw with evidence for ongoing extension until oligocene time towards the se these sequences are instead post kinematic directly overlaying a basement emplaced during breakup we interpret the palaeocene oligocene units to record the time spanning from the initiation of breakup late cretaceous palaeocene in the se to the end of extension oligocene in the nw the first ubiquitously post rift infill is the lower miocene maykop formation our results highlight the along strike temporal variability of extension and breakup processes in the ebsb

constraints on the upper crustal structure of the long valley mono craters volcanic complex eastern california from seismic refraction measurements during the summers of 1982 and 1983 field work was completed on 10 new seismic refraction profiles in the long valley mono craters region located within the technically active zone between the eastern sierra nevada and the basin and range province the four profiles presented here sample the upper 7 10 km of the crust within the western half of long valley cladera the mono craters ring fracture system and the normal crust north and northeast of long valley the entire area shares a common crystalline basement consisting primarily of mesozoic granitic rocks at a depth of 2 km beneath the topographic surface the p wave velocity is uniformly 5 6 km s beneath which the velocity increases with a gradient of about 0 1 s 1 clear secondary arrivals observed on a profile crossing the west part of the caldera support evidence from 1972 seismic refraction profiles for a reflecting boundary at a depth of 7 8 km beneath the west margin of the resurgent dome which may represent the top of a magma chamber structural details resolved in the upper 2 km of the crust lead to the following conclusions 1 p wave velocities in the crystalline basement at depths shallower than 2 km vary from 3 6 to 5 0 km s this variation reflects differences in the degree of fracturing of the upper portion of the basement 2 an apparently homogeneous basement in the upper 7 10 km beneath the mono craters ring fracture system indicates that any extensive magma chamber must be at least 10 km deep there 3 the downdropped crystalline basement beneath the western half of long valley caldera dips genty 5 10 to the northeast apparent offsets along steeply dipping caldera bounding faults are 1 0 1 7 km along the northern western and southern sides of the caldera with largest offsets in the north 4 rocks forming the caldera fill fall into essentially three p wave velocity groups from the surface downward these velocity groups are 100 400 of 1 2 1 8 km s material corresponding to unconsolidated fluvial or lacustrine deposits or highly fractured rhyolite flows 200 400 m of 2 8 3 1 km s material corresponding to sparsely jointed postcaldera rhyolite rhyodacite and basalt flows and approximately 1000 m of 3 9 4 4 km s material corresponding to deposits of bishop tuff

petrochemistry and petrology of i type granitoids in an arc setting the composite torul pluton eastern pontides ne turkey the upper cretaceous torul pluton located in the eastern pontides is of sub alkaline affinity and displays features typical of volcanic arc granitoids it is a composite pluton consisting of granodiorite biotite hornblende monzogranite quartz monzodiorite quartz monzonite and hornblende biotite monzogranite the oldest syenogranite 77 9 0 3 ma and the youngest quartz diorite form small stocks within the pluton samples from the granodiorites biotite hornblende monzogranites quartz monzodiorites quartz monzonites and hornblende biotite monzogranites have sio2 between 57 and 68 wt and display high k calc alkaline metaluminous to peraluminous characteristics chondrite normalized ree patterns are fractionated lacn lucn 6 0 14 2 with pronounced negative eu anomalies eu eu 0 59 0 84 initial nd i values vary between 3 1 and 4 1 initial 87sr 86sr values between 0 7058 and 0 7072 and 18o values between 4 4 and 7 3 the quartz diorites are characterized by relatively high mg number of 36 38 low contents of na2o 2 3 2 5 wt and sio2 52 55 wt and medium k calc alkaline metaluminous composition chondrite normalized ree patterns are relatively flat la yb cn 2 8 3 3 tb yb cn 1 2 and show small negative eu anomalies eu eu 0 74 0 76 compared to the other rock types radiogenic isotope signatures of the quartz diorites show higher 87sr 86sr 0 7075 0 7079 and lower nd i 4 5 to 5 3 the syenogranites have high sio2 70 74 wt and display high k calc alkaline peraluminous characteristics their ree patterns are characterized by higher lacn lucn 12 9 and eu eu 0 76 0 77 values compared to the quartz diorites isotopic signatures of these rocks nd i 4 0 to 3 3 87sr 86sr i 0 7034 0 7060 18 o 4 9 to 8 2 are largely similar to the other rock types but differ from that of the quartz diorites fractionation of plagioclase hornblende pyroxene and fe ti oxides played an important role in the evolution of torul granitoids the crystallization temperatures of the melts ranged from 800 to 900 c as determined from zircon and apatite saturation thermometry all these characteristics combined with low k2o na2o low al2o3 feot mgo tio2 and low na2o k2o feot mgo tio2 ratios suggest an origin through dehydration melting of mafic lower crustal source rocks

paleoclimatic evolution of the uvs nuur basin and adjacent areas western mongolia abstract the investigations presented in this paper focus on the shifts in pleistocene glaciations and the geomorphic changes in landforms as well as lake level changes and aeolian deposits of the last glacial interglacial cycle including the holocene geomorphic evidence and high lake levels show that the climate was more humid before the last glacial maximum lgm however at least one arid phase also occurred during the second half of the lgm the climate was dry and cold turning to wet and cold during the late glacial of the last ice age fluctuations in humidity and temperature occurred during the holocene since about 2000 yr bp the impact of human activity has increased

seismometer detection of dust devil vortices by ground tilt we report seismic signals on a desert playa caused by convective vortices and dust devils the long period 10 100 s signatures with tilts of 10 7 radians are correlated with the presence of vortices detected with nearby sensors as sharp temporary pressure drops 0 2 1 mbar and solar obscuration by dust we show that the shape and amplitude of the signals manifesting primarily as horizontal accelerations can be modeled approximately with a simple quasi static point load model of the negative pressure field associated with the vortices acting on the ground as an elastic half space we suggest the load imposed by a dust devil of diameter d and core pressure p o is 2 p o d 2 or for a typical terrestrial dust devil of 5 m diameter and 2 mbar about the weight of a small car the tilt depends on the inverse square of distance and on the elastic properties of the ground and the large signals we observe are in part due to the relatively soft playa sediment and the shallow installation of the instrument ground tilt may be a particularly sensitive means of detecting dust devils the simple point load model fails for large dust devils at short ranges but more elaborate models incorporating the work of sorrells 1971 may explain some of the more complex features in such cases taking the vortex winds and ground velocity into account we discuss some implications for the insight mission to mars online material figure of data and geophysical interpretation of seismic refraction line

crustal and time varying magnetic fields at the insight landing site on mars magnetic fields provide a window into a planet s interior structure and evolution including its atmospheric and space environments satellites at mars have measured crustal magnetic fields indicating an ancient dynamo these crustal fields interact with the solar wind to generate transient fields and electric currents in mars s upper atmosphere surface magnetic field data play a key role in understanding these effects and the dynamo here we report measurements of magnetic field strength and direction at the insight interior exploration using seismic investigations geodesy and heat transport landing site on mars we find that the field is ten times stronger than predicted by satellite based models we infer magnetized rocks beneath the surface within 150 km of the landing site consistent with a past dynamo with earth like strength geological mapping and insight seismic data suggest that much or all of the magnetization sources are carried in basement rocks which are at least 3 9 billion years old and are overlain by between 200 m and 10 km of lava flows and modified ancient terrain daily variations in the magnetic field indicate contributions from ionospheric currents at 120 km to 180 km altitude higher frequency variations are also observed their origin is unknown but they probably propagate from even higher altitudes to the surface we propose that the time varying fields can be used to investigate the electrical conductivity structure of the martian interior the magnetic field measured by the insight lander on mars varies daily and is ten times stronger than expected the field is inferred to originate from components of basement rocks magnetized by an ancient dynamo of earth like strength

initial results from the insight mission on mars nasa s insight interior exploration using seismic investigations geodesy and heat transport mission landed in elysium planitia on mars on 26 november 2018 it aims to determine the interior structure composition and thermal state of mars as well as constrain present day seismicity and impact cratering rates such information is key to understanding the differentiation and subsequent thermal evolution of mars and thus the forces that shape the planet s surface geology and volatile processes here we report an overview of the first ten months of geophysical observations by insight as of 30 september 2019 174 seismic events have been recorded by the lander s seismometer including over 20 events of moment magnitude mw 3 4 the detections thus far are consistent with tectonic origins with no impact induced seismicity yet observed and indicate a seismically active planet an assessment of these detections suggests that the frequency of global seismic events below approximately mw 3 is similar to that of terrestrial intraplate seismic activity but there are fewer larger quakes no quakes exceeding mw 4 have been observed the lander s other instruments two cameras atmospheric pressure temperature and wind sensors a magnetometer and a radiometer have yielded much more than the intended supporting data for seismometer noise characterization magnetic field measurements indicate a local magnetic field that is ten times stronger than orbital estimates and meteorological measurements reveal a more dynamic atmosphere than expected hosting baroclinic and gravity waves and convective vortices with the mission due to last for an entire martian year or longer these results will be built on by further measurements by the insight lander geophysical and meteorological measurements by nasa s insight lander on mars reveal a planet that is seismically active and provide information about the interior surface and atmospheric workings of mars

the low latitude monsoon climate during dansgaard oeschger cycles and heinrich events during the last 100 000 years dansgaard oeschger cycles d o cycles and heinrich events have been the dominant signal of past climate variability over greenland and the north atlantic the succession of stadials cold and interstadials warm associated with these cycles has been documented in records from the entire northern hemisphere south america new zealand antarctica the south atlantic and the southern ocean evidently climate forcing in the d o band affects both hemispheres the origin and cause of these teleconnected patterns is still unknown even if a large proportion of the cooling in europe and northern asia during heinrich events is a meteorological response to cold surface water in the north atlantic resulting from the surge of the laurentian and scandinavian ice sheets but this does not imply that the d o cycles are a priori caused by the collapse of these large icesheets a severe challenge to a primary origin from the northern ice sheet and north atlantic comes from the observation that warming in antarctica and the circumpolar current leads the north atlantic changes by some 1500 years charles et al 1996 blunier et al 1998 in the second part of the paper we investigate new deep sea records from the low latitude monsoon system mainly corroborating the result of schulz et al 1998 that the indian monsoon showed d o variability the abundance of eolian dust indicating continental humidity aridity in core 70kl from the arabian sea shows humid intervals which seem to correlate with temperature maxima in the antarctic vostok ice core apparently the low frequency sub milankovitch variability of the monsoon is associated with the southern hemisphere the d o scale component in the monsoonal climate on the other hand shows a succession of short humid intervals the sequence is most closely comparable to the greenland temperature record and to the stadial interstadial succession in the pacific santa barbara basin odp 893 in order to understand the global forcing of climate change in the d o band it appears necessary to quantify the phase relationships not only between d o cycles in the polar ice cores bender et al 1994 blunier et al 1998 steig et al 1998 but also between the low latitude pacific indian ocean and the high latitude records

the formation and inversion of the western greater caucasus basin and the uplift of the western greater caucasus implications for the wider black sea region the western greater caucasus formed by the tectonic inversion of the western strand of the greater caucasus basin a mesozoic rift that opened at the southern margin of laurasia subsidence analysis indicates that the main phase of rifting occurred during the aalenian to bajocian synchronous with that in the eastern alborz and possibly the south caspian basin secondary episodes of subsidence during the late tithonian to berriasian and hauterivian to early aptian are tentatively linked to initial rifting within the western and possibly eastern black sea and during the late campanian to danian to the opening of the eastern black sea initial uplift subaerial exposure and sediment derivation from the western greater caucasus occurred at the eocene oligocene transition oligocene and younger sediments on the southern margin of the former basin were derived from the inverting basin and uplifted parts of its northern margin indicating that the western greater caucasus basin had closed by this time a predominance of pollen representing a montane forest environment dominated by pinacean pollen within these sediments suggests that the uplifting caucasian hinterland had a paleoaltitude of around 2 km from early oligocene time the closure of the western greater caucasus basin and significant uplift of the range at approximately 34 ma is earlier than stated in many studies and needs to be incorporated into geodynamic models for the arabia eurasia region

structure of the oceanic lithosphere and upper mantle north of the gloria fault in the eastern mid atlantic by receiver function analysis receiver functions rf have been used for several decades to study structures beneath seismic stations although most available stations are deployed on shore the number of ocean bottom station obs experiments has increased in recent years almost all obss have to deal with higher noise levels and a limited deployment time 1 year resulting in a small number of usable records of teleseismic earthquakes here we use obss deployed as mid aperture array in the deep ocean 4 5 5 5 km water depth of the eastern mid atlantic we use evaluation criteria for obs data and beam forming to enhance the quality of the rfs although some stations show reverberations caused by sedimentary cover we are able to identify the moho signal indicating a normal thickness 5 8 km of oceanic crust observations at single stations with thin sediments 300 400 m indicate that a probable sharp lithosphere asthenosphere boundary lab might exist at a depth of 70 80 km which is in line with lab depth estimates for similar lithospheric ages in the pacific the mantle discontinuities at 410 km and 660 km are clearly identifiable their delay times are in agreement with prem overall the usage of beam formed earthquake recordings for obs rf analysis is an excellent way to increase the signal quality and the number of usable events

multiple porphyry cu mo events in the eastern pontides metallogenic belt turkey from early cretaceous subduction to eocene postcollision evolution four porphyry cu mo systems were investigated by re os molybdenite geochronology to constrain their timing with respect to the geodynamic and magmatic evolution of the eastern pontides turkey molybdenite from the ispir ulutas deposit yielded an re os age of 131 0 0 7 ma which is consistent with early cretaceous u pb laser ablation inductively coupled plasma mass spectrometry la icp ms zircon ages of local calc alkaline intrusions it demonstrates that porphyry deposits were already formed during early cretaceous subduction of the neotethys along the eastern pontides and that they can be correlated with porphyry cu events in the adjacent lesser caucasus molybdenite re os ages of 76 0 0 4 and 75 7 0 4 ma at the elbeyli prospect and 77 2 1 0 ma at the emeksen prospect overlap with u pb la icp ms zircon ages of shoshonitic to high k calc alkaline intrusions in the region which were emplaced during late cretaceous neotethys subduction a 50 7 0 3 ma molybdenite re os age at the guzelyayla deposit confirms porphyry cu mo emplacement coeval with eocene postcollisional calc alkaline adakitic magmatism of the eastern pontides an electron microprobe study of molybdenite samples supplemented by data obtained during re os dating shows that the eocene guzelyayla deposit and the late cretaceous emeksen prospect have the highest re enrichment postcollisional melting of a thickened mafic lower continental crust and melting of a metasomatized lithospheric mantle with little to no interaction with upper crustal rocks may explain the re enrichment at guzelyayla and emeksen respectively

millennial reoccurrence of century scale abrupt events of east asian monsoon a possible heat conveyor for the global deglaciation high resolution sediment records from the south china sea reveal a winter monsoon dominated glacial regime and a summer monsoon dominated holocene regime during the last glacial cycle a fundamental change between regimes occurred during deglaciation through a series of millennial reoccurrences of century scale changes in the east asian monsoon eam climate these abrupt events centered at 17 0 15 9 15 5 14 7 13 5 13 9 13 3 12 1 11 5 and 10 7 14c ka correlate well with the millennial scale events in the santa barbara basin and the arabian sea i e a relationship between eam and el nino southern oscillation systems the abrupt increases in summer monsoon imply enhanced heat transport from low latitude sea area to the midlatitude high latitude land area the phase relationship between events of eam and ice sheet may reflect a faster eam response and a slower ice sheet response to the insolation change a far reaching conclusion is that the eam might have triggered the northern hemisphere deglaciation

crust stratigraphy and heterogeneities of the first kilometers at the dichotomy boundary in western elysium planitia and implications for insight lander abstract insight landed on mars on november 26 2018 in western elysium planitia the mars crust beneath the lander is subject to complex geologic history next to the great topographic and crustal dichotomy of mars understanding this part of the martian crust in the subsurface would aid future investigations of the internal structure of the planet based on seismic datasets collected by the seismic experiment for interior structure seis instrument here we investigate the subsurface structure and composition from the analysis of mineralogy and morphology of exposures in impact craters as well as on scarps and knobs in the general region of elysium planitia using a combination of orbital datasets we identify exposures of subsurface materials with distinct composition and physical properties we find olivine and pyroxene detections associated with small impact craters 1 5 7 km rim in the vicinity of insight lander as well as in the transition unit and elysium volcanic unit fe mg phyllosilicates have been identified in the central peak of the 51 km diameter kalpin crater and on knobs in the transition unit between the dichotomy and the plains in addition eroded meter scale layered unit subject to erosion has been identified in six impact craters to the north east of the landing site including kalpin crater massive bedrock and layered weak materials co occur in the transition unit indicating a complex origin these results together suggest both materials with altered composition and layered deposit occur as distinct geologic units beneath the basaltic lava flow units through analogy with terrestrial sedimentary rocks or clay bearing sediments we suggest physically weak materials exist beneath the lava flow units in the general region of elysium planitia the spatial distribution and continuity of these materials are unclear due to the lack of exposures within the lava flow unit where the insight lander is located these subsurface materials of distinct physical properties may result in increased attenuation or reverberations of seismic waves to be collected by seis the findings suggest a close investigation of the potential effects of subsurface stratigraphy on seismic data would help inform future data interpretation and understanding of the internal structure of mars

timing of neotectonic fracturing by fission track dating of obsidian in filling faults in the ikizdere rize area ne black sea region turkey there are several ne sw and nnw sse trending sets of neotectonic faults that are infilled with obsidians in the district of the ne black sea region turkey using the fission track technique it is estimated that these fracturefilling obsidians were formed between 1 73 0 10 and 1 93 0 15 ma this short period is consistent with a unique eruption and is supported by petrographic and geochemical data that reveal very homogenous characteristics although existing literature data indicate that these faults are part of the early pliocene neotectonic fracture system in this region the determination of latest pliocene pleistocene formation for the obsidians better constrains its timing

insights from petrography mineralogy and u pb zircon geochronology into the provenance and reservoir potential of cenozoic siliciclastic depositional systems supplying the northern margin of the eastern black sea the eastern black sea is one of the few remaining underexplored hydrocarbon basins in europe reservoir quality is a key risk factor in the basin the analysis of up dip portions of oligocene to pliocene depositional systems exposed around its northern and eastern margins enable the composition and provenance of sandstones within the basin to be predicted two major sources of quartz rich sandstone are present the russian western greater caucasus which became a subaerial sediment source in the oligocene and the east european craton scythian platform these are predicted to form better quality reservoirs at shallow and moderate burial depths than their rock fragment rich counterparts due to lesser amounts of compactional porosity loss oligo miocene sandstones from the russian western greater caucasus were deposited as turbidites in the tuapse trough sandstones from the east european craton scythian platform were largely trapped within the indolo kuban basin north of the greater caucasus they only entered the eastern black sea in large volumes from latest miocene or pliocene time in the region of the kerch taman shelf at the western tip of the greater caucasus however it is possible that a precursor to this system supplied the oligocene to early miocene reservoir sandstones within the subbotina field the dziruli massif in western georgia also generated quartz rich sandstones but these are not thought to have entered the black sea

gold deposits and occurrences of the greater caucasus georgia republic their genesis and prospecting criteria abstract the south central part of the greater caucasus region georgia republic represents an extremely prospective region for significant orogenic gold deposits gold bearing quartz veins are concentrated in two extensive wnw trending belts the mestia racha and svaneti districts within the northern margin of the southern slope zone of the great caucasus orogen this metalliferous region is dominated by early to middle jurassic slates which are part of a terrane that likely accreted to the continental margin from late paleozoic to jurassic the slates were subsequently intruded by both middle to late jurassic and neogene granitoids quartz veins in the more carbonaceous slate units are most consistently enriched in as au hg sb and w and show mineralization styles most consistent with typical orogenic gold deposits quartz veins in the mestia racha district were mined in soviet times for as sb and w but many of these are now being recognized as gold resource targets the veins occur in the footwall of a thrust fault between the southern slope zone and an earlier accreted terrane the main zone to the north many veins in the district continue along strike for 1 km and some cut neogene intrusions constraining ore formation to the most recent 4 to 5 million years gold deposition thus correlates with final collision of the arabian plate to the south and uplift of the ore hosting greater caucasus the zopkhito deposit previously mined for antimony contains an estimated 55 t au at a cutoff grade of 0 5 g t the veins are localized in an area where smaller order structures show a major change in strike from n s to more e w trends a pyrite arsenopyrite ore stage includes gold concentrated in both sulfide phases it is overprinted by a later stibnite dominant stage fluid inclusion studies of ore samples from the zopkhito deposit indicate minimum trapping temperatures of 300 to 350 c and 200 to 300 c for the two stages respectively and minimum trapping pressures of 0 2 to 0 5 kbar ore forming fluids with approximately 5 to 20 mol non aqueous gas evolved from n2 dominant to co2 dominant during evolution of the hydrothermal system 34s values of 1 to 4 for ore related sulfides at zopkhito are consistent with a sedimentary rock source for the sulfur and 18o quartz measurements of 16 to 21 are consistent with either a magmatic or metamorphic fluid more than 60 gold bearing lodes and placers in the svaneti district occur along the thrust between the southern slope and main zones lode gold potential was first recognized in the historic placer district in the 1980s with many auriferous quartz veins cutting middle jurassic igneous rocks brecciated veins in the 18 t au lukhra deposit cut a small granodioritic to dioritic stock the latter intrudes devonian schist immediately north of the thrust presently there are three recognized ore zones in the deposit with the most significant occurring over an area 140 m in length and 12 m wide with typical grades of 7 to 9 g t au reconnaissance fluid inclusion studies of ore samples from the lukhra deposit indicate minimum trapping temperatures of 220 c measurements of 18oquartz of about 10 suggest buffering of isotopic composition by the igneous host rocks

evidence for a warm humid climate in arid northwestern china during 40 30 ka bp abstract former shorelines and sedimentary records from several lake basins in northwestern china xinjiang qinghai give evidence for warm and humid climatic conditions during 40 30 ka bp further indications of this favorable climate period are derived from palaeosols from the ili loess and from cemented calcareous layers on the terraces of the keriya river at the southern margin of the tarim basin and in the badain jaran desert in inner mongolia at that time annual mean temperature in the qaidam basin was 2 c higher and in the western part of inner mongolia even 2 3 c higher than today precipitation in most parts of northwestern china was between 60 300 mm greater than today these changes were probably a consequence of an increase in ocean surface temperature and evaporation resulting from a higher radiation input at middle and low latitudes caused by changes in the earth s precessional cycle as a result of these orbital changes it is suggested that the intensified westerly circulation was responsible for increased moisture over northwestern china

first seismic receiver functions on the moon we applied the s receiver function technique farra and vinnik 2000 to the recordings of deep moon quakes at seismograph station apollo 12 in order to detect phases converted sp and reflected beneath the station we detected sp phases from the base of the surficial low velocity zone and from the mantle crust boundary the average p velocity in the surficial layer 1 km thick should be a few times higher than in reference model toksoz et al 1974 the observed time amplitude and waveform of sp phase from the mantle crust boundary are close to those predicted by the reference model but with a modified surficial layer the s wavetrains within the first 10 s may contain waves scattered in the mantle this scattering is stronger than in the earth at comparable depths the polarized component in the coda waves that we observe is another previously unknown phenomenon

subsurface structure at the insight landing site from compliance measurements by seismic and meteorological experiments measurements of ground compliance at the insight landing site describing the surface response to pressure loading are obtained from seismic and meteorological data compliance observations show an increase with frequency indicating the presence of a stiffer rock layer beneath the exposed regolith we performed a markov chain monte carlo inversion to investigate the vertical profile of the elastic parameters down to 20 m below insight compliance was inverted both freely and assuming prior knowledge of compaction in the regolith and the limitations and strengths of the methods were assessed on the basis of theoretical considerations and synthetic tests the inverted young modulus exhibits an increase by a factor of 10 100 over the first 10 15 m compatible with a structural discontinuity between 0 7 and 7 m the proposed scheme can be used for joint inversion of other seismic geological or mechanical constraints to refine the resulting vertical section

lagrangian based simulations of hypervelocity impact experiments on mars regolith proxy most of the surface of mars is covered with unconsolidated rocky material known as regolith high fidelity models of the dynamics of impacts in such material are needed to help with the interpretation of seismic signals that are now recorded by seis the seismometer of insight we developed a numerical model for impacts on regolith using the novel hybrid optimization software suite hoss which is a lagrangian code mixing finite and discrete element formulations we use data from hypervelocity impact experiments performed on pumice sand at the nasa ames vertical gun range to identify and calibrate key model parameters the model provides insight into the plastic elastic transition observed in the data and it also demonstrates that gravity plays a key role in the material response waveforms for receivers situated vertically below the impact point are correctly modeled while more research is needed to explain the shallow receivers signals

the black sea a tertiary basin observations and insights abstract there has been a longstanding debate on the age and kinematics of the opening of the black sea basin this paper presents an alternative interpretation to that drawn by nikishin et al 2015a b based on the same data these demonstrate that the terminal phase of extensional faulting in the black sea occurred in the paleocene and as such the age of the oceanic crust under both the eastern and western black sea is entirely of tertiary age these conclusions are based on the application of seismic stratigraphic principles to the seismic and well data already published by nikishin and co workers a basin wide discordance here termed base passive infill separates pre and syn kinematic section black sea rifting from the post kinematic infill of a pre existing failed rift based on the aforementioned published material this surface post dates pre and syn kinematic cretaceous strata on the mid black sea high and is capped by post kinematic tertiary section the surface can be traced regionally throughout the black sea indicating that for much of their history the western and eastern black sea basins opened simultaneously

verifying single station seismic approaches using earth based data preparation for data return from the insight mission to mars abstract the planned insight mission will deliver a single seismic station containing 3 component broadband and short period sensors to the surface of mars in 2016 while much of the progress in understanding the earth and moon s interior has relied on the use of seismic networks for accurate location of sources single station approaches can be applied to data returned from mars in order to locate events and determine interior structure in preparation for the data return from insight we use a terrestrial dataset recorded at the global seismic network station bfo located at the black forest observatory in germany to verify an approach for event location and structure determination based on recordings of multiple orbit surface waves which will be more favorable to record on mars than earth due to smaller planetary radius and potentially lower background noise with this approach applied to events near the threshold of observability on earth we are able to determine epicentral distance within approximately 1 corresponding to 60 km on mars and origin time within 30 s with back azimuth determined from rayleigh wave polarization absolute locations are determined generally within an aperture of 10 allowing for localization within large tectonic regions on mars with these locations we are able to recover earth mantle structure within 5 the insight mission requirements for martian mantle structure using 1d travel time inversions of p and s travel times for datasets of only 7 events the location algorithm also allows for the measurement of great circle averaged group velocity dispersion which we measure between 40 and 200 s to scale the expected reliable frequency range of the insight data from earth to mars data using the terrestrial data we are able to resolve structure down to 200 km but synthetic tests demonstrate we should be able to resolve martian structure to 400 km with the same frequency content given the smaller planetary size

reconstruction of the 30 40 ka bp enhanced indian monsoon climate based on geological records from the tibetan plateau abstract multi proxy records from ice caps lakes and pollen records from the tibetan plateau are used to reconstruct the palaeoclimate during the period 30 40 ka bp lake geomorphological and lacustrine sedimentological studies show that numerous high lake level stands and or freshwater lakes occurred in large areas of western china at this time including over the tibetan plateau where the area contains mostly shallow water and saline hypersaline water lakes under extremely dry conditions of today pollen based reconstruction of tibetan vegetation shows systematic differences from the present alpine steppe forests were shifted ca 400 km further north and the alpine conifer forest extended ca 400 800 km beyond their present western limits variations in 18 o curves from ice cores from the plateau suggest that the temperature was 2 4 c higher and precipitation was 40 to over 100 higher than today all of the evidence consistently suggests the existence of an exceedingly strong summer monsoon climate over the plateau the vigorous evaporation of the tropical ocean surface would also play an important role in promoting the penetration of moisture rich southwest monsoon over the tibetan plateau these climate patterns with strong summer monsoon circulation during the period 30 40 ka bp reflect the 20 ka earth orbital precessional cycle when the tibetan plateau region received greater solar radiation which thus enlarged the thermodynamical contrast between the plateau and the mid south portion of the indian ocean

a probabilistic framework for single station location of seismicity on earth and mars abstract locating the source of seismic energy from a single three component seismic station is associated with large uncertainties originating from challenges in identifying seismic phases as well as inevitable pick and model uncertainties the challenge is even higher for planets such as mars where interior structure is a priori largely unknown in this study we address the single station location problem by developing a probabilistic framework that combines location estimates from multiple algorithms to estimate the probability density function pdf for epicentral distance back azimuth and origin time each algorithm uses independent and complementary information in the seismic signals together the algorithms allow locating seismicity ranging from local to teleseismic quakes distances and origin times of large regional and teleseismic events m 5 5 are estimated from observed and theoretical body and multi orbit surface wave travel times the latter are picked from the maxima in the waveform envelopes in various frequency bands for smaller events at local and regional distances only first arrival picks of body waves are used possibly in combination with fundamental rayleigh r1 waveform maxima where detectable depth phases such as pp or pmp help constrain source depth and improve distance estimates back azimuth is determined from the polarization of the rayleigh and or p wave phases when seismic signals are good enough for multiple approaches to be used estimates from the various methods are combined through the product of their pdfs resulting in an improved event location and reduced uncertainty range estimate compared to the results obtained from each algorithm independently to verify our approach we use both earthquake recordings from existing earth stations and synthetic martian seismograms the mars synthetics are generated with a full waveform scheme axisem using spherically symmetric seismic velocity density and attenuation models of mars that incorporate existing knowledge of mars internal structure and include expected ambient and instrumental noise while our probabilistic framework is developed mainly for application to mars in the context of the upcoming insight mission it is also relevant for locating seismic events on earth in regions with sparse instrumentation

a preliminary investigation into the relationship between long period seismic noise and local fluctuations in the atmospheric pressure field summary the displacement response of an elastic half space to a plane pressure wave is examined in order to establish the conditions under which sources of this type can contribute significantly to the long period seismic noise field the study is restricted to pressure waves which propagate at velocities well below the seismic wave velocities characteristic of the half space the numerical studies indicate that pressure waves with amplitudes of 100 pbar or more can contribute significantly to the long period vertical background noise observed at the surface provided that the detectors are located on sections of alluvial fill or poorly to moderately indurated sandstones and shales whose thicknesses are greater than about a kilometre these same waves can also create significant tilt noise on long period horizontal seismographs located at or near the surface regardless of the rock type the seismic disturbances created by pressure waves decay rapidly away from the surface therefore it appears that it may be possible to eliminate the effects of atmospherically generated noise by placing the detectors at moderate depths

earth motion caused by local atmospheric pressure changes summary observations have been made of the local atmospheric pressure field and the long period seismic noise fields both on the surface of the earth and in a mine at a depth of 183 metres the observations show that during windy intervals and in the period range 20 100 s there is a strong correlation between local atmospheric pressure changes and the noise recorded by a vertical seismograph located on the surface in contrast over the same range of periods there is no correlation between the seismic noise recorded in the mine and local atmospheric pressure changes except during the passage of acoustic waves it is shown that the noise in this pass band is not due to the buoyant response of the seismograph but is caused by the motion of the earth responding to atmospheric pressure changes

the removal of free surface interactions from three component seismograms summary the effect of the free surface can be removed from three component seismic recordings to recover the incident upgoing wavefield if the slowness and azimuth of the current wavefront are known as a function of time for a single threecomponent station it is usually possible to estimate an azimuth for an event from the first arriving p waves but slowness estimates are less reliable when more than one wavetype is presented in the seismic wavetrain however the free surface correction operators are generally slowly varying functions of slowness and so some error in slowness can be tolerated effective approximations for the removal of the free surface effects can be made for hard rock sites to cover slowness bands for the main regional phases pn pg sn and lg by applying these operators in turn over group velocity windows appropriate to the particular phases the relative amplitude of the p sv and sh contributions to the wavefield can be estimated because the free surface amplification effects have been removed the amplitudes can be compared directly and provide useful constraints on the radiation characteristics of the source this procedure is therefore helpful for developing discrimination measures for different classes of sources

residence time of diffuse waves in the crust as a physical interpretation of coda q application to seismograms recorded in mexico summary we consider a simple model for elastic wave propagation in the earth s litho sphere consisting of a heterogeneous and scattering crust overlying a homogeneous mantle that is we neglect backscattering from the upper mantle this rough condition is not strictly valid everywhere but this model allows us to investigate the effects of variations of diffracting properties between crust and mantle on the coda decay the free parameters describing the wave propagation are the mean free path of the waves and the intrinsic absorption in the crust in the framework of the radiative transfer theory we treat accurately jumps in s wave speed and the mean free path at the moho without intrinsic absorption this configuration yields a synthetic coda decay 1 texp 2 ft qc a form similar to that proposed by aki chouet 1975 to parametrize the observations the exponential decay in our purely elastic model is due to the partial leakage of diffuse energy into the mantle in order to test the applicability of our model we have determined the coda q parameter qc in the 1 15 hz frequency band from data recorded at four stations in mexico in the low frequency regime around 1 hz we suggest that the energy leakage significantly affects coda q whilst at higher frequencies around 10 hz the anelastic attenuation dominates a weak intrinsic absorption expressed by a frequency independent parameter qi of about 1000 accounts satisfactorily for the observed qc values in the whole frequency range our very simple model has only two free parameters and offers an attractive alternative physical interpretation of coda q in mexico this model is sufficient to interpret the coda observations according to our model in regions where the mean free path is much larger than the crustal thickness weakly heterogeneous crust the leakage effect should be small and the observed qc will mainly be due to the intrinsic absorption on the other hand when the mean free path is of the order of the crustal thickness strongly heterogeneous crust we predict a strong sensitivity of the decay rate of the coda to the crustal thickness this dependence may be important for the interpretation of the regional variations of coda q we propose introducing a new parameter d the residence time of diffuse energy in the crust which is physically more meaningful than a quality factor to quantify the leakage effect

lake evolution in the tengger desert northwestern china during the last 40 000 years climatic changes inferred from lacustrine deposits and lake level fluctuations in northwestern and central china are mainly based on paleoclimatic records from the tibetan plateau while there is still a lack of data relating to the semiarid arid desert regions of inner mongolia in the tengger desert different paleolake levels at baijian hu are documented by six paleoshorelines and stratified lake carbonates the highest lake level occurred ca 39 000 14c yr b p and prevailed over about 16 000 km2 from sediment structure geochemical composition and ostracods we infer humid cool conditions until 23 000 14c yr b p in the northern badanjilin desert at gaxan nur sogu nur high lake levels can be deduced from mollusc bearing paleobeaches and lake carbonates which have been dated to 34 000 14c yr b p and indicate a lake that covered some 32 000 km2 after ca 20 000 yr b p the climate became dry with increased eolian activity and decreasing lake levels reestablishment of wet conditions occurred ca 13 000 yr b p the holocene is represented by stratified lake deposits that alternate with fluvial and eolian deposits indicating a longterm oscillating trend toward arid conditions the existence of widespread freshwater lakes during the late pleistocene indicates a semihumid climate without an accompanying fall in temperature to arctic conditions

stratigraphic and structural development of the eastern pontides turkey this paper describes the stratigraphic and structural development of the eastern pontides north turkey based on section logging at eight localities construction of three structural profiles across the mountains and published literature the eastern pontides comprise a late carboniferous to miocene sequence resting on a basement of hercynian metamorphics late carboniferous to scythian sediments are continental clastics interpreted as having been deposited in an extensional half graben the middle triassic is limestone reflecting the development of a south facing passive margin in the late triassic the ocean palaeotethys began to close flysch was deposited in most places with minor shallow water limestones in the sinemurian above an inverted half graben all pre aalenian strata were deformed during the cimmerian orogeny after a phase of subduction related volcanism in the mid jurassic limestones were deposited during the late jurassic and early cretaceous mainly in shallow water the aptian and albian are absent due to doming in the western pontides prior to the opening of the western black sea but there is a thick sequence of upper cretaceous arc volcanic rocks and intervening turbidites the upper palaeocene is absent possibly due to rifting in the eastern black sea major compression affected the pontides from the eocene to the pliocene associated with the closure of the tethyan ocean oligocene and younger rocks are accordingly non marine

scattering attenuation profile of the moon implications for shallow moonquakes and the structure of the megaregolith abstract we report measurements of the attenuation of short period seismic waves in the moon based on the quantitative analysis of envelope records of lunar quakes our dataset consists of waveforms corresponding to 62 events including artificial and natural impacts shallow moonquakes and deep moonquakes recorded by the four seismometers deployed during apollo missions 12 14 15 and 16 to quantify attenuation and distinguish between elastic scattering and inelastic absorption mechanisms we measure the time of arrival of the maximum of energy t max and the coda quality factor q c the former is controlled by both scattering and absorption while the latter is an excellent proxy for absorption consistent with the strong broadening of seismogram envelopes in the moon we employ diffusion theory in spherical geometry to model the propagation of seismic energy in depth dependent scattering and absorbing media to minimize the misfit between predicted and observed t max for deep moonquakes and impacts we employ a genetic algorithm and explore a large number of depth dependent attenuation models quantified by the scattering quality factor q sc or equivalently the wave diffusivity d and the absorption quality factor q i the scattering and absorption profiles that best fit the data display very strong scattering attenuation q sc 10 or equivalently very low wave diffusivity d 2 km2 s in the first 10 km of the moon these values correspond to the most heterogeneous regions on earth namely volcanic areas below this surficial layer the diffusivity rises very slowly up to a depth of approximately 80 km where q sc and d exhibit an abrupt increase of about one order of magnitude below 100 km depth q sc increases rapidly up to approximately 2000 at a depth of about 150 km a value similar to the one found in the earth s mantle by contrast the absorption quality factor on the moon q i 2400 is about one order or magnitude larger than on earth our results suggest the existence of an approximately 100 km thick megaregolith which is much larger than what was previously thought the rapid decrease of scattering attenuation below this depth is compatible with crack healing through viscoelastic mechanisms using our best attenuation model we invert for the depth of shallow moonquakes based on the observed variation of t max with epicentral distance on average they are found to originate from a depth of about 50 km 20 km which suggests that these earthquakes are caused by the failure of deep faults in the brittle part of the moon

tectonic units of the alpine collision zone between eastern alps and western turkey abstract we present a map that correlates tectonic units between alps and western turkey accompanied by a text providing access to literature data explaining the concepts used for defining the mapped tectonic units and first order paleogeographic inferences along strike similarities and differences of the alpine eastern mediterranean orogenic system are discussed the map allows 1 for superimposing additional information such as e g post tectonic sedimentary basins manifestations of magmatic activity onto a coherent tectonic framework and 2 for outlining the major features of the alpine eastern mediterranean orogen dinarides hellenides anatolides and taurides are orogens of opposite subduction polarity and direction of major transport with respect to alps and carpathians and polarity switches across the mid hungarian fault zone the dinarides hellenides taurides and apennines consist of nappes detached from the greater adriatic continental margin during cretaceous and cenozoic orogeny internal units form composite nappes that passively carry ophiolites obducted in the latest jurassic earliest cretaceous or during the late cretaceous on top of the greater adriatic margin successions the ophiolites on top of composite nappes do not represent oceanic sutures zones but root in the suture zones of neotethys that formed after obduction suturing between greater adria and the northern and eastern neotethys margin occupied by the tisza and dacia mega units and the pontides occurred in the latest cretaceous along the sava izmir ankara erzincan suture zones the rhodopian orogen is interpreted as a deep crustal nappe stack formed in tandem with the carpatho balkanides fold thrust belt now exposed in a giant core complex exhumed in late eocene to miocene times from below the carpatho balkan orogen and the circum rhodope unit its tectonic position is similar to that of the sakarya unit of the pontides we infer that the rhodope nappe stack formed due to north directed thrusting both rhodopes and pontides are suspected to preserve the westernmost relics of the suture zone of paleotethys

recent tectonic stress evolution in the lesser caucasus and adjacent regions the stress indicators describing the recent provided by active tectonics framework and palaeo stress provided by micro fault kinematics and volcanic cluster patterns show the scale and temporal changes in stress states since the beginning of arabian eurasian collision the recent stress derived from the active fault kinematics in the lesser caucasus and adjacent area corresponds to a strike slip regime with both transtension and transpression characteristics the kinematics of active structures of various scale are conditioned by tectonic stress field with general north south compression and east west extension the distribution of neogene to quaternary volcanic cluster geometries and micro fault kinematic data evidence the time and orientation variability of the stress field since the beginning of the arabian eurasian collision in addition to the general north south compression orientation two other nw se and ne sw secondary orientations are observed the first one was dominant between the palaeogene and the late early miocene and the second one has prevailed between the late miocene and the quaternary since the continental collision of arabia with eurasia the tectonic stress regime in the lesser caucasus and adjacent area changed from compression thrusting and reverse faulting to transtension transpression strike slip faulting with various vertical components

quaternary paleoenvironmental change on the tibetan plateau and adjacent areas western china and western mongolia abstract this paper summarises the nature of climatic change during the last glacial interglacial cycle on the tibetan plateau and adjacent areas the results are derived from inland glacier fluctuations lake level changes and dust loess records of central asia including tibet these are based on our field investigations from 1988 to 1998 and literature surveys the changing extents of different climatic controlled geomorphic landscapes and vegetation zones help to provide estimates of the magnitude of climatic change features such as ice wedge casts loess and palaeosols ela reconstruction s and palaeobotanical data are used to help reconstruct palaeoprecipitation and palaeotemperatures weathering characteristics the overlying strata and some luminescence dates indicate that there are two main glacial ice advances during the last glacial cycle these correspond to marine oxygen isotope stages ois 2 and 4 in some areas as the eastern or northern margin of the tibetan plateau remnants of older glaciations are preserved higher lake levels in the deserts of central asia and on the tibetan plateau are dated to 40 to 25 ka ois 3 and to late glacial early to mid holocene periods our work supports the view that in many areas of central asia cold phases during the last glacial correspond with the maximum extent of glaciers and the periglacial activity the last glaciation produced large alluvial fans alternating with periods of high lake stands on the tibetan plateau however at the northern margin of the plateau in the qaidam basin and in some particular desert areas in western china high lake levels occurred also during the pleistocene and are related with alluvial fans

variscan orogeny in the black sea region two gondwana derived paleozoic belts rim the archean paleoproterozoic nucleus of the east european platform in the black sea region in the north is a belt of paleozoic passive margin type sedimentary rocks which extends from moesia to the istanbul zone and to parts of the scythian platform the mois block this belt constituted the south facing continental margin of the laurussia during the late paleozoic this margin was deformed during the carboniferous by folding and thrusting and forms the variscan foreland in the south is a belt of metamorphic and granitic rocks which extends from the balkanides through strandja sakarya to the caucasus bassac block the protoliths of the metamorphic rocks are predominantly late neoproterozoic granites and paleozoic sedimentary and igneous rocks which were deformed and metamorphosed during the early carboniferous there are also minor eclogites and serpentinites mostly confined to the northern margin of the bassac block typical metamorphism is of low pressure high temperature type and occurred during the early carboniferous visean 340 330 ma coevally with that observed in the central europe volumetrically more than half of the crystalline belt is made up of carboniferous earliest permian 335 294 ma granites the type of metamorphism its concurrent nature over 1800 km length of the bassac block and voluminous acidic magmatism suggest that the thermal event probably occurred in the deep levels of a continental magmatic arc the bassac arc collided with laurussia in the mid carboniferous leading to the foreland deformation the ensuing uplift in the permian resulted in the deposition of continental red beds which are associated with acidic magmatic rocks observed over the foreland as well as over the bassac block in the black sea region there was no terminal collision of laurussia with gondwana during the late paleozoic and the laurussia margin continued to face the paleo tethyan ocean in the south

geochemical characteristics of the composite kackar batholith generated in a neo tethyan convergence system eastern pontides turkey abstract the composite kackar batholith of cretaceous to late eocene age consists of various intrusions derived from different geodynamic settings ranging from early to mature arc through collision to post collisional extension in the neo tethyan convergence system of the eastern pontides of ne turkey the intrusions were emplaced into cretaceous and middle eocene volcano sedimentary units and are unconformably overlain by late cretaceous early to middle eocene and miocene units the 10 lithological units are grouped into five geodynamic associations on the basis of geological setting and geochemical characteristics 1 early arc origin as represented by the medium k calc alkaline calk camlikaya granitoid of early cretaceous age 2 mature arc origin as represented by the medium to high k calc alkaline sirtyayla and marselevat granitoids of late cretaceous to early palaeocene age 3 syn collisional plutonism as represented by the peraluminous asniyor leucogranite of palaeocene age 4 post collisional plutonism as represented by the high k calc alkaline ayder k feldspar megacrystic granitoid and the sasmistal microgranite of middle to late eocene age 5 the extension related mildly alkaline gullubag monzonite the medium k calc alkaline to slightly tholeiitic thol halkalitas quartz diorite and the low k tholeiitic ardesen gabbro and isina diabase of late eocene age that are mainly exposed as small shallow stocks and n s ne sw nw se and e w trending veins

temporal variation and frequency dependence of seismic ambient noise on mars from polarization analysis we applied a polarization analysis of insight seismic data to estimate temporal variation and frequency dependence of the martian ambient noise field an autocorrelation analysis suggests that a li

c2 c pyroxene phenocrysts from three potassic series in the neogene alkaline volcanics ne turkey their crystal chemistry with petrogenetic significance as an indicator of p t conditions chemical and structural data are reported for c2 c pyroxene phenocrysts collected from three potassic series group a basanite tephrite group b tephrite pho nolitic tephrite group c alkaline basalt trachybasalt of the neogene alkaline volcanics navs in northeastern turkey in order to investigate the evolution of the mag matic plumbing system and the location of magma chamber s with crystallization conditions the rock series hosting the clinopyroxene phenocrysts show generally porphyritic texture and have a variable phenocryst rich nature 20 58 with phenocryst assemblages character ized by cpx ol plag foid amp bio the clinopyroxene phenocrysts can be chemically classified as ti and fe 3 rich al diopsides for groups a and b ab cpxs and ti and fe 3 poor al diopsides for group c c cpxs they have poorly variable composition clustering in the diopside field structurally the diopside groups have nearly similar a ranging from 9 73 to 9 75 a u vcell 437 2 440 9 a u 3 and hbetai angle values 106 01 106 23 but some differences in polyhedral parameters and geometries of the ab cpxs and c cpxs have been observed for example the ab cpxs are characterized by

late cretaceous early eocene tectonic development of the tethyan suture zone in the erzincan area eastern pontides turkey six individual tectonostratigraphic units are identified within the izmir ankara erzincan suture zone in the critical erzincan area of the eastern pontides the ayikayasi formation of campanian maastrichtian age is composed of bedded pelagic limestones intercalated with polymict massive conglomerates the ayikayasi formation conformably overlies the tauride passive margin sequence in the munzur mountains to the south and is interpreted as an underfilled foredeep basin the refahiye complex of possible late cretaceous age is a partial ophiolite composed of 75 by volume serpentinized peridotite mainly harzburgite 20 diabase and minor amounts of gabbro and plagiogranite the complex is interpreted as oceanic lithosphere that formed by spreading above a subduction zone unusual screens of metamorphic rocks e g marble and schist locally occur between sheeted diabase dykes the upper cretaceous karayaprak melange exhibits two lithological associations 1 the basalt radiolarite serpentinite association including depleted arc type basalts 2 the massive neritic limestone lava volcaniclastic association that includes fractionated intermediate composition lavas and is interpreted as accreted neotethyan seamount s the several kilometre thick karadag formation of campanian maastrichtian age is composed of greenschist facies volcanogenic rocks of mainly basaltic to andesitic composition and is interpreted as an emplaced upper cretaceous volcanic arc the campanian early eocene sutpinar formation 1500 m thick is a coarsening upward succession of turbiditic calcarenite sandstone laminated mudrock volcaniclastic sedimentary rocks that includes rare andesitic lava and is interpreted as a regressive forearc basin the late paleocene eocene sipikor formation is a laterally varied succession of shallow marine carbonate and siliciclastic lithofacies that overlies deformed upper cretaceous units with an angular unconformity structural study indicates that the assembled accretionary prism supra subduction zone type oceanic lithosphere and volcanic arc units were emplaced northwards onto the eurasian margin and also southwards onto the tauride gondwana related margin during campanian maastrichtian time further mainly southward thrusting took place during the eocene in this area related to final closure of tethys our preferred tectonic model involves northward subduction supra subduction zone ophiolite genesis and arc magmatism near the northerly eurasian margin of the mesozoic tethys

late pleistocene evolution of salt lakes in the qaidam basin qinghai province china abstract the qaidam basin is a tectonically controlled depression at 2700 m altitude on the northern margin of the qinghai xizang tibet plateau rimmed by the high aljun qilian ranges to the north and kunlun peaks to the south rising above 5000 m the basin floor experiences hyper arid conditions with evaporation precipitation ratios exceeding 100 1 periglacial and glacial conditions prevail on montane peaks with permafrost above 3800 m on the basin floor small waterbodies lie on extensive halite salt flats on the largest the qarhan salt flat 5800 km2 in extent the small lakes dabuxun and taijinier represent contracted remnants of a once expansive water body throughout neogene time a succession of clastic sediments indicates lake depo centre migration from nw to se towards late pliocene evaporitic conditions developed with formation of gypsum halite celestite mirabilite and bloedite continued deformation through pleistocene time has developed a series of nw se trending domes and troughs this setting has continued to exert a controlling influence on basin and brine evolution with progressive development through sulfate to chloride brines as dry conditions intensified in late pleistocene expanded lake conditions qarhan mega lake corresponding to near the 2800 m contour indicate the existence of past climates much more humid than those of today a drilling program has defined the lateral and vertical extent of evaporitic halite deposits freshwater clastics and shell deposits which predate the halite phase indicate humid lacustral conditions until after 40 000 30 000 yr b p desiccation from about 25 000 yr until about 9000 yr b p resulted in deposition of halite to 60 m thick with thin parting muds representing brief returns to more humid environments high lake shorelines with aragonitic ooids surrounding the dry playa kunteyi and high level ostracod rich beach and near shore deposits on xiao qaidam attest to the presence of expanded late pleistocene lacustral conditions on lakes other than qarhan preceding the final evaporite stage clastic sediments associated with the halite are dominated by loessial silts equivalent to the late pleistocene malan deposits of central china simultaneous halite and loess deposition reflect the dry conditions that developed in the qaidam basin during the latter part of the last glaciation and which have persisted ever since the final evolution of brines has resulted in development of extensive potassium rich brines and salts with the mineral carnallite providing the basis for a large potash extraction industry near golmud the hydrologic history documented by the analyses of lake sediments reflects the interaction of tectonic deformation and climatic change in the development of brines to the potash stage

seismic velocity structure of the lunar mantle i have inverted the recently completed set of seismic arrival times from the apollo lunar seismic network to estimate the average seismic velocities in three sections of the lunar mantle two for the upper mantle and one for the middle mantle the method used is a variation of the linearized least squares inversion where the inversion is accomplished in steps the estimated average velocities in the upper mantle decrease from vp 7 74 km s and vs 4 49 km s in the section above 270 km depth to vp 7 46 km s and vs 4 25 km s in the section between 270 and 500 km depth confirming the earlier finding of negative gradients based on seismic amplitude variations the average velocities in the middle mantle between the depths of 500 km and 1000 km of vp 8 26 km s and vs 4 65 km s are significantly higher than those in the upper mantle contradicting earlier estimates based on more limited data the higher velocities may suggest initial melting of the moon down to at least 1000 km depth

correlation between climate events in the north atlantic and china during the last glaciation episodes of massive iceberg release heinrich events 1 3 into the north atlantic ocean during the last glaciation were associated with recurring episodes of unusually cold north atlantic surface water bond cycles 4 and cold air temperatures over greenland dansgaard oeschger events 5 6 four of the youngest of these cold events have also been reported in climate records from sites outside the north atlantic region7 but until now the entire suite has been identified only in north atlantic marine sediments greenland ice core records and tentatively in french lake sediments8 here we examine grain size data from chinese loess and intercalated accretionary palaeosols of last glacial age for evidence of similar climate signals remote from the north atlantic region we see grain size maxima with ages that match those of the last six heinrich events which we interpret as an indication of the changing strength of the east asian winter monsoon which largely controls the transport and deposition of central asian aeolian dust thus it seems that these heinrich events have left their signature in the chinese loess record this is consistent with simulations of the glacial climate9 which imply that the climates of the north atlantic and china were linked by the effect of westerly winds

petrogenesis of the post collisional volcanic rocks from the borcka artvin area implications for the evolution of the eocene magmatism in the eastern pontides ne turkey abstract whole rock geochemistry 40 ar 39 ar data and sr nd isotopes are presented for the eocene borcka volcanic rocks on the eastern corner of the eastern pontide orogenic belt ne turkey borcka artvin volcanic rocks are divided into three suites basic dyke borcka basalt and civankoy suite these rocks contain plagioclase an 49 88 clinopyroxene wo 38 49 en 38 54 fs 8 25 hornblende mg 0 57 0 74 phenocrysts and magnetite titanomagnetite and apatite microphenocrysts 40 ar 39 ar ages on hornblendes ranging from 46 9 0 1 to 39 9 0 5 ma within the middle eocene the volcanic rocks show tholeiitic calc alkaline affinities and have low to medium k contents they are enriched in large ion lithophile lile and light rare earth elements lree with pronounced depleted high field strength elements hfse the chondrite normalized ree patterns la cn lu cn 1 19 show low to medium enrichment indicating similar sources for the rock suite initial 87 sr 86 sr values 87 sr 86 sr 46 ma vary between 0 70423 and 0 70495 while initial 143 nd 144 nd values 143 nd 144 nd 46 ma lie between 0 51263 and 0 51285 the main solidification processes involved in the evolution of the volcanics consist of fractional crystallization with minor amounts of crustal contamination all our evidences support the conclusion that the parental magma of the rocks probably derived from an enriched mantle previously metasomatized by fluids derived from subducted slab in a post collisional extension related geodynamic setting

sedimentology and stratigraphy of cenozoic deposits in the kagizman tuzluca basin northeastern turkey the kagizman tuzluca basin is located in the northeastern anatolia to the east of the intersection point near karliova of the major north and east anatolian fault systems this intermontane basin displays a thick sequence over 2000 m of mostly terrestrial deposits represented by repetitive alternations of the lake and fluvial environments ranging from late eocene oligocene to middle late miocene a marine incursion only mappable in the southeastern margin of the basin deposited limestones and sandy limestones rich in marine mollusks and nummulites in particular n fichteli that constrain an early oligocene age for this marine unit kagan fm the terrestrial basin fill deposits show different thicknesses throughout the basin due to irregular bottom topography and tectonic configuration of the basin margins the thickest deposits were accumulated along the different margins of the basin which received high quantities of siliciclastics from meandering river alluvial and coastal fans fan delta gilbert type delta and wave worked fluvial delta climate changes have also driven the development of lake environments during distinct depositional periods siliciclastic dominated overfilled lakes halikislak and kizilkaya formations and chemical dominated underfilled lakes turabi and tuzluca formations were formed they have been also classified as newark type and fundy type lakes respectively fluvial systems evolved from high energy meandering rivers deposited under humid climate gungoren formation to low energy meandering rivers resulted from arid and semiarid climates cincavat formation the transitional intervals from ephemeral river dry mudflat cincavat formation to saline pan lake tuzluca formation indicate wadi sand flat playa fluvial systems the chronostratigraphic constrains of the entire sequence remain poor and so far solely based on vertebrate fossil assemblages the evaporitic tuzluca formation would be middle miocene in age due to its stratigraphic position over the cincavat formation