acoustics variability of air gun signals recorded at intermediate ranges within the lau basin 1 during january february 2009 an active source seismic survey was performed over the eastern lau spreading center in the lau back arc basin 21 s 176 s acoustic signals generated by ther v langseth s 36 gun pneumatic source array were recorded within the deep sound channel at offsets of 29 416 km the local ocean acoustic environment is everywhere bottom limited with seafloor depths within the study domain ranging from 1700 2800 m low frequency 4 125 hz sound levels are monitored using root mean square energy flux density and zero to peak measurement techniques from these field data transmission loss is found to exceed the predictions of a geometric spherical spreading model at similar ranges arrival amplitudes vary by up to 20 db and durations vary by a factor of three to six the depth of the seafloor beneath the air gun source exhibits a positive correlation with arrival duration and a negative correlation with range corrected amplitude explaining up to 30 of the observed variation in both parameters the strength of this correlation however varies for stations lying at different azimuths highlighting the importance of seafloor aspect and slope in the coupling of bottom interacting acoustic energy into the sound channel range dependent ray tracing shows that shots deployed over shallower seafloor are more likely to produce sound channel trapped signals that propagate with limited bottom interaction this results in arrivals that are more impulsive with shorter durations and higher amplitudes shots deployed in deeper water typically undergo a larger number of bounces and are characterized by more emergent longer duration and smaller amplitude arrivals

dynamic deformation of seguam island aleutian islands alaska 1993 2000 implications for magmatic and hydrothermal processes 1 the most recent volcanic eruption on seguam island was detected in december 1992 and lasted until july or august of 1993 a series of radar interferograms generated from imagery collected by the european space agency s ers 1 and ers 2 satellites are used here to map the spatial and temporal evolution of the deformation field from june of 1993 to september of 2000 this evolution consists of a coeruptive period of uplift surrounding the eruption two posteruptive subsidence signals centered within each of the two calderas on the island each of which lasted for 4 years after the end of the eruption and then uplift beneath the caldera on the eastern side of the island and the surrounding region from mid 1999 through the end of the time series in september 2000 the locations and magnitudes of the sources of the deformation are inferred from the interferometric synthetic aperture radar displacement data using an elastic half space earth model with multiple mogi point sources and a levenburg marquardt nonlinear inversion technique this inference reveals that the sources of subsidence are located within the upper 2 km of the earth s crust while the sources of uplift are located below 2 5 km the locations of dilatational sources are consistent with a model of the volcanic system where ascending magma accumulates below a density or structural boundary near 2 5 3 km depth the subsidence signals are most likely associated with cooling of shallow magmatic bodies emplaced during the 1992 1993 eruption however the possibility that they indicate a combination of magma cooling and depressurization of a hydrothermal system cannot be ruled out using the geodetic data alone implications for the long term evolution of the volcanic edifice are discussed

lethal sandslides from eolian dunes fossil vertebrates entombed within the upper cretaceous djadokhta formation of southern mongolia bear testimony to a heretofore unknown geologic phenomenon mass wasting of eolian dunes during heavy rainstorms evaporation of shallow penetrating rainwater led to progressive calcite accumulation in a thin layer of sand about 0 5 m below the surface of dune lee slopes during rare heavy rainstorms a perched water table developed at the top of calcitic zones positive pore water pressure led to translational slides and fast moving sediment gravity flows that overwhelmed animals on the lee slopes of large dunes and in interdune areas

alleged vertebrate eggs from upper cretaceous redbeds gobi desert are fossil insect coleoptera pupal chambers fictovichnus new ichnogenus small egg like structures from the upper cretaceous campanian djadokhta formation of mongolia were previously interpreted as casts of crocodile lizard and turtle eggs or as inorganic nodules identical structures from coeval redbeds at bayan mandahu in northern china indicate the structures are not vertebrate eggs nor of vertebrate origin comparisons with recent and quaternary beetle coleoptera pupal chambers show close similarities in size shape and the presence of a round to irregular exit hole for the adult beetle most importantly the cretaceous structures are enveloped by a thin clay rich zone which is expected if constructed by beetle larvae but inexplicable in any egg or inorganic nodule model additional evidence contradicting a vertebrate egg origin for the structures includes i the structures are too small to have been laid by turtle or crocodile species occurring in the bayan mandahu redbeds ii the structures are isolated not in clutches or pairs and iii unlike newly hatched soft shelled lizard eggs the cretaceous structures are not collapsed and show a round to irregular exit hole rather than a slit it is concluded that the egg like structures are sand casts steinkerns of beetle pupal chambers probably of scarabaeidae tenebrionidae or curculionidae the cretaceous pupal chambers are assigned to a new ichnogenus fictovichnus and new ichnospecies fictovichnus gobiensis and fictovichnus parvus

a cautionary tale of topography and tilt from kīlauea caldera we conduct finite element analysis to investigate the effect of sharp topography on surface ground deformation caused by pressure changes in a magma reservoir tilt data expresses the horizontal gradient of vertical deformation and therefore can emphasise small variations in deformation that go unnoticed using other methods we find that the vertical displacement profile at a surface with a cliff can be thought of as the superposition of the deformation from shallow and deeper sources this combination can create a small peak in vertical displacement that acts as a pseudo source creating a reversal of the deformation gradient and therefore anomalous tilt magnitude and a rotation of up to 180 we apply these models to k lauea caldera and find that surface geometry creates a tilt rotation of 10 partially explaining anomalous tilt that has been observed our analysis highlights the importance of considering topography when assessing tilt measurements at active volcanoes

fossil bee nests coleopteran pupal chambers and tuffaceous paleosols from the late cretaceous laguna palacios formation central patagonia argentina abstract the late cretaceous laguna palacios formation in central patagonia san jorge basin southern south america is composed of tuffaceous deposits supplied by periodical volcanic ash falls partly reworked by rivers on broad plains variations in ash fall rates allowed the formation of stacked mature paleosols which are one of the most characteristic features of this formation the mature paleosols show well developed horizons ped structure and bear an intricate network of trace fossils mostly produced by small roots and invertebrates two different insect trace fossils could be recognized in this formation sweat bee nests and coleopteran pupal chambers fossil bee nests are composed of inclined tunnels with cells attached to them by means of short necks a typical construction of bees of the subfamily halictinae similar halictine constructions were reported from the cretaceous of the usa coleopteran pupal chambers are discrete ovoid structures having an internal cavity with a smooth surface and an outer wall of lumpy appearance composed of different layers of soil material they are commonly constructed by the larvae of different families of coleoptera similar trace fossils were previously reported from the asencio formation late cretaceous early tertiary of uruguay and from the djadokhta formation of mongolia late cretaceous these trace fossils constitute some of the only paleontological data from the laguna palacios formation allowing inferences about its paleoecology paleoclimatology and paleogeography ecological preferences of halictinae as well as some features of the nests suggest a temperate seasonal climate and an environment dominated by low vegetation for the laguna palacios formation which is also compatible with sedimentologic and pedogenic evidence the morphology of the nests typical of north american halictinae adds more evidence to the hypothesis of the existence of faunal interchange between north and south america by the late cretaceous the fossil nests constitute some of the oldest evidence of bees in the fossil record the third known record of bees of cretaceous age and the first for the southern hemisphere the two traces described are together with those of dakota and the gobi desert the only trace fossils from paleosols of cretaceous age that can be certainly attributed to insects

modeling of surface deformation in volcanic areas the 1970 1972 and 1982 1984 crises of campi flegrei italy campi flegrei is a densely inhabited volcanic area within a caldera 12 14 km in diameter immediately west of naples italy in 1970 1972 and in 1982 1984 campi flegrei experienced considerable ground surface deformation producing a bulge about 3 5 m high at its peak in the two inflation episodes the point of maximum uplift did not change coinciding with the caldera center about which the displacements exhibited radial symmetry the 1982 1984 uplift was accompanied by considerable seismic activity gravity changes have been interpreted as reflecting the occurrence of a subvertical magmatic intrusion volcanological petrological and geophysical data point to the existence of a shallow magma chamber just beneath the center of the caldera we assume that the observed surface displacements are the response of an essentially elastic medium to a pressure increase in the magma chamber static deformation is calculated by using a finite element method assuming axial symmetry around a vertical axis through the caldera center the role played by various components of the model geometry boundary conditions elastic properties is analyzed it is shown that models assuming uniform elasticity are inadequate therefore the major volcanotectonic features as well as the influence of temperature and pressure on the elastic properties are taken into account the results of various more complex models are presented it is suggested that a progressively fractured zone whose size and shape depend also on the possible occurrence of magmatic intrusions may explain the observed surface displacements and the other data collected at campi flegrei it is suggested that the 1970 1972 uplift was possibly accompanied by larger scale changes in the stress field

paleoenvironments and ichnotaxonomy of insect trace fossils in continental mudflat deposits of the miocene calatayud daroca basin zaragoza spain the miocene continental deposits in the orera area calatayud daroca basin are composed of red and brown mudstones deposited in the dry mudflat sepiolite and dolomicrites deposited in periodically desiccated alkaline shallow lakes by direct precipitation and mudstones with carbonate laminae formed in wet mudflat areas by groundwater cementation during rise of water table the mudstone sepiolite dolomite sequences represent dry wet cycles two different ichnospecies of insect trace fossils were found fictovichnus gobiensis and fictovichnus aragon n isp fictovichnus gobiensis are 15 18 mm long 8 9 mm wide ellipsoid casts showing smooth surface one end is rounded whereas a truncated tunnel protrudes from the other they have no discrete wall but some show an outer micritic layer one end of fictovichnus aragon n isp is rounded and the other pointed the holotype is 26 mm long and 9 mm wide in the contact with the matrix specimens show two micritic layers interpreted as remains of the original silky wall constructed by the wasp larva in both chnospecies the micromorphology of the casts is similar to the matrix where they are found possible producers of fictovichnus gobiensis are coleopterans whereas fictovichnus aragon was probably produced by sphecid or pompilid wasps indicative of subaerial exposition fictovichnus gobiensis is found in all four facies environments occurrence of fictovichnus aragon n isp restricted to the wet mudflat is controlled by a shallow groundwater that permit the growth of phreatophytic plants but also the nesting of wasps in dry upper soil horizons and b the rise of groundwater table that favoured decomposition of plants and cementation and preservation of the traces

thermal activity and ground deformation at phlegrean fields italy precursors of eruptions or fluctuations of quiescent volcanism a contribution of geochemical studies the ground uplift that occurred at phlegrean fields during the crisis of 1982 1984 is analyzed by taking into account the volcanological history of the area the available geophysical information and the data obtained through our systematic geochemical study the chemical composition of the products of a unique historical eruption in a d 1538 displays a strong evolved character and fits the hypothesis of a progressive reduction in size of the magma body which probably behaved as a closed system the bicarbonate contents of the thermal waters in the area has increased with time suggesting inputs of carbon dioxide into the shallow aquifers temperatures at the fumaroles have not changed for at least a hundred years indicating that boiling aquifer at depth feeds the surface manifestations significant variations in the ratios h2s co2 and h2 n2 observed at the same time suggest that both the rate of ground uplifting and the increase of seismic energy release may be related to the fluctuation of a convective flow from a deep heat source tectonic activity can modify the permeability of deep structures and thereby trigger increased activity in surface manifestations

modelling of surface ground deformations in the phlegraean fields volcanic area italy a preliminary finite elements model of the ground deformations observed at phlegraean fields is proposed the model assumes an oblate spheroid magma chamber at the depth of 5 4 km with major semiaxis of 1 5 km and minor semiaxis of 0 75 kin the dimensions of the magma chamber have been evaluated by using a thermal model based on the assumptions that a progressively cooling huge magmatic body is responsible for the volcanic activity at phlegraean fields in the last 35 000 years surface deformations caused by an overpressure of 30 mpa in the magma chamber have been calculated constant and temperature dependent elastic parameters of the surrounding medium have been considered vertical displacements of the order of those presently observed at phlegraean fields can be obtained only with temperature dependent elastic properties of the medium

inflation model of uzon caldera kamchatka constrained by satellite radar interferometry observations 1 we analyzed radarsat 1 synthetic aperture radar sar data to compute interferometric sar insar images of surface deformation at uzon caldera kamchatka russia from 2000 to 2003 approximately 0 15 m of inflation occurred at uzon caldera extending beneath adjacent kikhpinych volcano this contrasts with insar data showing no significant deformation during either the 1999 to 2000 or 2003 to 2004 time periods we performed three sets of numerical source inversions to fit insar data from three different swaths spanning 2000 to 2003 the preferred source model is an irregularly shaped pressurized crack dipping 20 to the nw 4 km below the surface the geometry of this solution is similar to the upper boundary of the geologically inferred magma chamber extension of the surface deformation and source to adjacent kikhpinych volcano without an eruption suggests that the deformation is more likely of hydrothermal origin possibly driven by recharge of the magma chamber

step filling and development of a three layer magma chamber the neapolitan yellow tuff case history abstract the neapolitan yellow tuff the product of the largest known trachytic phreatoplinian eruption gives a good opportunity to investigate the filling mechanisms and internal dynamics of a trachytic magma chamber a detailed study of the geochemical mineralogical and isotopical features of the deposit was carried out to investigate the behaviour of the magma chamber before the eruption the collected data show three distinct compositional groups separated by gaps single depositional units contain glass shards formed contemporaneously although each of these shards is homogeneous they display the same compositional variations and gaps detected in pumice clasts this feature is taken as an evidence for interpreting the detected compositional gaps as real gaps in the chamber therefore the chamber was filled by three distinct magma bodies separated by compositional gaps the uppermost magma was alkali trachyte and highly homogeneous likely a consequence of vigorous convection the intermediate magma was trachyte with a slight and continuous compositional variation likely resulting from less intense convection the lowermost magma was compositionally zoned from alkali trachyte to latite downward this compositional zonation was most likely acquired during uprise from a deeper reservoir the three magmas entered the chamber sequentially from the uppermost to the lowermost the latter entered the chamber short before the beginning of the eruption its input was interpreted as a possible triggering factor for the eruption the results of this study strongly support a step filling mechanism for the neapolitan yellow tuff magma chamber and allow definition of the temporal succession of input of magma batches furthermore they also suggest that the magma bodies did not mix although at least the uppermost two coexisted inside the chamber for a time long enough to allow internal homogeneization by convection

geochemical and b sr nd isotopic evidence for mingling and mixing processes in the magmatic system that fed the astroni volcano 4 1 3 8 ka within the campi flegrei caldera southern italy abstract the astroni volcano was built through seven eruptions that generated pyroclastic deposits and lava domes within the campi flegrei caldera southern italy 4 1 3 8 ka bp whole rock geochemical and b sr nd isotopic investigations were carried out on representative samples of all seven eruptions the products vary from tephriphonolites to phonolites and from latites to trachytes they show textural mineralogical and isotopic evidence of disequilibrium including distinct clinopyroxene populations rounded and or resorbed plagioclase and alkali feldspar and reverse zoned phenocrysts of all these mineral phases the sr nd and b isotopic composition of whole rocks is variable and correlated with the degree of chemical evolution suggesting open system processes in addition to fractional crystallisation moreover significant sr isotopic disequilibrium between the phenocrysts and glass has been documented for one sample the chemostratigraphy of the products indicates that astroni eruptions 1 through 5 were fed by magmas of trachytic to phonolitic composition that were less enriched in radiogenic sr and 11b up section this variability has been interpreted as the result of mingling between at least two distinct magmatic end members one more evolved and the other less evolved another heterogeneous batch of magma resulting from almost complete mixing between the same two end members was drained during eruptions 6 and 7 the more evolved end member characterised by 87sr 86sr 0 7075 143nd 144nd 0 51247 and 11b 8 was very similar to the magma that fed the final phases of the agnano monte spina eruption which occurred a few centuries earlier in the astroni vent area the less evolved end member had 87sr 86sr 0 70726 143nd 144nd 0 51251 and 11b 10 and was likely derived by fractional crystallisation of a mantle derived magma an abrupt decrease in both the sr isotope ratio and the th content detected at the transition between unit 4 and 5 suggests that another magma with a 87sr 86sr ratio intermediate between those of the two identified end members may have been involved in astroni activity the more evolved end member is interpreted as a residue of the agnano monte spina eruption that was invaded by either the intermediate or the less evolved magmatic end member promoting mingling and triggering astroni activity this study of astroni provides insights for both short and long term volcanic hazard assessment as the astroni volcano is the best example of a very close sequence of eruptions from the same vent area in the campi flegrei caldera

the cordilleran ribbon continent of north america the north american cordilleran orogen is the result of a two stage process a triassic jurassic accretion within panthalassa forming saybia a composite ribbon continent and b late cretaceous collision of saybia with north america this model requires that a large portion of the continental foreland of the orogen is exotic the exotic continental component of saybia cassiar platform is distinguished from the autochthon on the basis of its a triassic eurasian fauna b involvement in a major late triassic early jurassic orogenic event and c young in part grenvillian basement and mantle a mid cretaceous magmatic arc records west dipping subduction beneath the east margin of saybia the related accretionary prism consists of imbricated shale chert and deep water limestones the medial basin and overlies an isotopically juvenile mantle domain carbonatite complexes delineate the cryptic suture separating saybia and the autochthon paleomagnetic and paleobotanical data place saybia 2000 km to the south relative to the autochthon at 80 ma late cretaceous thrust belt development records transpression between the north moving ribbon continent and the autochthon pinning against the okhotsk chukotka arc in siberia buckled saybia giving rise to the alaskan promontory

the active portion of the campi flegrei caldera structure imaged by 3 d inversion of gravity data 1 we present an improved density model and a new structural map of the neapolitan yellow tuff caldera the active portion of the nested campi flegrei caldera the model was built using a new 3 d inversion of the available high precision gravity data and a new digital terrain and marine model the inversion procedure based on a variable depth lumped assembling of the subsurface gravity distribution via cell aggregation gives better defined insights into the internal caldera architecture that well agree with the available geological geophysical and geochemical data the adopted 3 d gravity method is highly efficient for characterizing the shallow caldera structure down to 3 km depth and defining features related to regional or volcano tectonic lineaments and dynamics in particular the resulting density distribution highlights a pronounced density low in correspondence of the central portion of the caldera with a detail not available till now the joint interpretation of the available data suggests a subsurface structural setting that supports a piecemeal collapse of the caldera and allows the identification of its headwall positive gravity anomalies localize dense intrusions presently covered by late volcanic deposits along the caldera marginal faults and the main structural lineaments both bordering the resurgent block and cutting the caldera floor these results allow us to both refine the current geological structural framework and propose a new structural map that highlights the caldera boundary and its internal setting this map is useful to interpret the phenomena occurring during unrest and to improve both short term and long term volcanic hazards assessment

simple shearing block resurgence in caldera depressions a model from pantelleria and ischia abstract similar resurgent blocks occur in caldera depressions at the islands of pantelleria and ischia the two blocks which are tilted show similar deformation patterns and similar distributions of volcanic vents related to resurgence the remaining parts of the floors of the two calderas are not deformed similarities between the two features are so striking that the resurgence mechanism must have been alike a dynamic model for resurgence is presented and called simple shearing block resurgence the triggering mechanism is an increase of the magmatic pressure in the upper part of a shallow magma chamber which results in a vertical direction of the maximum stress applied on the roof rocks the block is first defined by high angle inland dipping marginal detachments and then deformed through a simple shearing mechanism reverse faults on its mostly uplifted side determine an horizontal shortening of the block which is balanced on the opposite side by normal faults oblique movements take place along the other two sides due to this distribution of the stress around the block magmas can reach the surface only through the extensional faults on the less uplifted side

mechanical response of the south flank of kilauea volcano hawaii to intrusive events along the rift systems abstract increased earthquake activity and compression of the south flank of kilauea volcano hawaii have been recognized by previous investigators to accompany rift intrusions we further detail the temporal and spatial changes in earthquake rates and ground strain along the south flank induced by six major rift intrusions which occurred between december 1971 and january 1981 the seismic response of the south flank to individual rift intrusions is immediate the increased rate of earthquake activity lasts from 1 to 4 weeks horizontal strain measurements indicate that compression of the south flank usually accompanies rift intrusions and eruptions emplacement of an intrusion at a depth greater than about 4 km such as the june 1982 southwest rift intrusion however results in a slight extension of the subaerial portion of the south flank horizontal strain measurements along the south flank are used to locate the january 1983 east rift intrusion which resulted in eruptive activity the intrusion is modeled as a vertical rectangular sheet with constant displacement perpendicular to the plane of the sheet this model suggests that the intrusive body that compressed the south flank in january 1983 extended from the surface to about 2 4 km depth and was aligned along a strike of n66 e the intrusion is approximately 11 km in length extended beyond the january 1983 eruptive fissures which are 8 km in length and is contained within the 14 km long region of shallow rift earthquakes

simulating the mechanism of magmatic processes in the campi flegrei area southern italy by the lorenz equations the up down motion at campi flegrei may be due to the internal dynamics of the system and does not necessarily require a push such as a new input of magma from outside the different eruptive phases which have occurred at campi flegrei might be related to deterministic chaotic magma flows similar to those studied in simple experimental systems and theoretically well schematized by the so called lorenz equations here different convective cells are hypothesized to operate at decreasing time and spatial scales they are found to reasonably explain the volcanic history of campi flegrei starting from the campanian ignimbrite phase through the yellow tuff up to the monte nuovo event and the recent bradyseismic crises 3 2002 elsevier science b v all rights reserved

late cretaceous to middle tertiary basin evolution in the central tibetan plateau changing environments in response to tectonic partitioning aridification and regional elevation gain located in the bangong suture zone between the lhasa and qiangtang terranes of central tibet the nima basin records cretaceous late miocene sediment accumulation during a period of drastically changing paleogeography and paleoelevation the bangong suture zone originally formed during late jurassic early cretaceous time as the lhasa terrane collided with the qiang tang terrane during early to middle cretaceous time the region lay at northern near equatorial paleolatitudes near sea level by aptian time the nima basin was above sea level and was strongly influenced by nearby volcanic activity and crustal shortening in the reactivated bangong suture zone in the southern nima basin an 50 m y late cretaceous eocene depositional hiatus correlates with major crustal shortening and ensuing voluminous ignimbrite eruptions in the lhasa terrane in the northern nima basin deposition continued during latest cretaceous time recording arid paleoclimate in evaporitic lacustrine and eolian dunefield deposits by oligocene time the nima basin comprised two independent depocenters that accumulated coarse grained alluvial fluvial lacustrine evaporitic and fan delta deposits in close association with reactivated thrusts in the bangong suture zone carbon and oxygen isotope data from oligocene paleosol carbonate reported elsewhere indicate that regional paleoelevation during the late oligocene was 4 6 km as it is today overall the depositional record of the nima basin combined with ongoing structural and geochronologic studies demonstrates that the bangong suture zone was reactivated during middle cretaceous and middle tertiary time that the intervening 50 m y interval was a time of regional upper crustal shortening in the lhasa terrane followed by regional ignimbrite eruptions and that arid paleoclimate and high paleoelevation were established by the late cretaceous and late oligocene respectively within the context of other data sets from the lhasa terrane the record of deposition in the nima basin is consistent with low angle subduction of neotethyan oceanic lithosphere and reactivation of the bangong suture zone during the early cretaceous followed by shortening within the gangdese retroarc and northern lhasa terrane thrust belts during the late cretaceous lithospheric delamination dripping and regional magmatic flare up during latest cretaceous through early tertiary time and underthrusting of indian lower crust and lithosphere as far north as the bangong suture zone during late oligocene time

axi symmetric deformation of a thermo poro elastic half space inflation of a magma chamber summary the deformation observed at phlegraean fields italy during the recent 1982 1984 crisis is interpreted in terms of overpressure in a shallow magma chamber and migration of hot pressurized fluids elastic effects are studied first and previous results obtained from maruyama s strain nuclei are corrected poro elastic and thermo elastic effects are found to be as important as the elastic ones in a semi pervious medium the three terms are typically of the same magnitude results are applied to interpreting the bradyseismic crisis of 1982 84 at phlegraean fields pf near naples italy the concave shape of the first phase of the deformation history at pf can be reproduced by linearly increasing fluid pressure and or temperature at the boundary of a spherical cavity the convex shape of the second phase is interpreted in terms of a gradual return to normal conditions the late phase of slow subsidence is interpreted as the effect of diffusional dissipation of temperature and pressure excess the deconvolution of the real source time history at pf is largely non unique but in any case the importance of fluids in the deformation history is assessed furthermore the inclusion of fluid migration in the deformation model allows simple explanations of several geochemical and geophysical observations made during the bradyseismic crisis

ichnotaxonomy and ichnostratigraphy of chambered trace fossils in palaeosols attributed to coleopterans ants and termites

the thermal regime of the campi flegrei magmatic system reconstructed through 3d numerical simulations abstract we illustrate a quantitative conductive convective thermal model incorporating a wide range of geophysical petrological geological geochemical and isotopical observations that constrain the thermal evolution and present state of the campi flegrei caldera cfc magmatic system the proposed model has been computed on the basis of the current knowledge of 1 the volcanic and magmatic history of the volcano over the last 44 ka 2 its underlying crustal structure and 3 the physical properties of the erupted magmas 3d numerical simulations of heat conduction and convection within heterogeneous rock magma materials with evolving heat sources and boundary conditions that simulate magma rise from a deep 8 km depth to shallow 2 6 km reservoirs magma chamber formation magma extrusion caldera collapse and intra caldera hydrothermal convection have been carried out the evolution of the cfc magmatic system through time has been simulated through different steps related to its changes in terms of depth location and size of magma reservoirs and their replenishment the thermal modeling results show that both heat conduction and convection have played an important role in the cfc thermal evolution although with different timing the simulated present heat distribution is in agreement with the measured geothermal profiles agip 1987 reproduces the thermal gradient peaks at the cfc margins in correspondence to the anomalies in surface gradients corrado et al 1998 and suggests temperatures of 700 c at depth of 4 km in the central portion of the caldera in agreement with the estimated temperature for the brittle ductile transition hill 1992

oldest evidence of osteophagic behavior by insects from the triassic of brazil abstract this study reports the earliest known evidence of osteophagy by invertebrates in a continental setting from the middle and upper triassic santa maria supersequence parana basin brazil samples from the dinodontosaurus assemblage zone pinheiros chiniqua sequence middle triassic and the hyperodapedon assemblage zone candelaria sequence upper triassic were analyzed and a number of trace morphologies were found including tubes holes and channels we report the occurrence of cubiculum inornatus from the middle triassic and osteocallis mandibulus from the upper triassic and diagnose a new ichnospecies o infestans isp nov the occurrence of these trace morphologies suggests that insect bone modification behavior originated in triassic gondwanic environments and dispersed during the mesozoic achieving a more cosmopolitan distribution during the cretaceous

taphonomy of the prosauropod dinosaur sellosaurus and its implications for carnivore faunas and feeding habits in the late triassic abstract the stubensandstein upper triassic norian is a complex system of fluvial deposits in southwest germany and yields one of the most diverse records of fossil vertebrates from the european continental triassic taphonomic data from 17 partial skeletons of the prosauropod dinosaur sellosaurus gracilis are presented with emphasis on a recently rediscovered field sketch of one particular specimen the preservational states and burial postures of individuals forming a practically monospecific prosauropod assemblage indicates in situ preservation of single specimens most likely by miring in unconsolidated fluvial sands covered by floodplain deposits shed teeth of carnivores and the mode of preservation suggest that one of the prosauropod carcasses was scavenged at least two different types of predators several individuals of a large indeterminate primitive archosaur and a phytosaur left traces of their activities during scavenging on the carcass the prosauropod carnivore tooth assemblage provides the first evidence that deep snouted phytosaurs with heterodont dentitions were capable of manipulating and feeding on large terrestrial prey moreover scavenger prey assemblages in the norian of central europe support the hypothesis that large carnivorous basal archosaurs as represented for example by rauisuchians were replaced by theropod dinosaurs in the late triassic

ordosemys leios n gen n sp a new turtle from the early cretaceous of the ordos basin inner mongolia ordosemys leios n gen n sp from the early cretaceous luohandong formation zhidan group ordos basin inner mongolia is a primitive aquatic turtle with a reduced fenestrated plastron it shares with the members of the centrocryptodira the presence of well formed articular surfaces on the cervical and caudal vertebrae within the centrocryptodira characters of the cervical vertebrae suggest it is more closely related to the polycryptodira than is the meiolaniidae ordosemys shares with the chelydridae the presence of two procoelous anterior caudals but this character may be primitive for the polycryptodira characters of the basicranial region of the braincase shared by ordosemys and the chelonioidea support a sister group relationship between these two taxa but a sister group relationship between ordosemys and the polycryptodira is more strongly supported by characters shared by the chelonioidea and other members of the polycryptodira

on the discovery of an oviraptorid skeleton on a nest of eggs at bayan mandahu inner mongolia people s republic of china a partial skeleton of oviraptor which means egg thief collected at bayan mandahu inner mongolia people s republic of china in 1990 was lying on top of a nest of eggs of the six known skeletons of this genus from upper cretaceous djadokhtan sediments this is the second occurrence in which the theropods were interacting with the eggs when they were buried by sand and dust during sandstorms two explanations for the association of oviraptor with eggs are that the theropod may have been eating the eggs or it may have been incubating and protecting them evidence presented suggests that the latter hypothesis is more likely it is also conceivable that the female oviraptorid was in the process of laying eggs when she died

archean to recent aeolian sand systems and their sedimentary record current understanding and future prospects the sedimentary record of aeolian sand systems extends from the archean to the quaternary yet current understanding of aeolian sedimentary processes and product remains limited most preserved aeolian successions represent inland sand sea or dunefield erg deposits whereas coastal systems are primarily known from the cenozoic the complexity of aeolian sedimentary processes and facies variability are under represented and excessively simplified in current facies models which are not sufficiently refined to reliably account for the complexity inherent in bedform morphology and migratory behaviour and therefore cannot be used to consistently account for and predict the nature of the preserved sedimentary record in terms of formative processes archean and neoproterozoic aeolian successions remain poorly constrained palaeozoic ergs developed and accumulated in relation to the palaeogeographical location of land masses and desert belts during the triassic widespread desert conditions prevailed across much of europe during the jurassic extensive ergs developed in north america and gave rise to anomalously thick aeolian successions cretaceous aeolian successions are widespread in south america africa asia and locally in europe spain and the usa several eocene to pliocene successions represent the direct precursors to the present day systems quaternary systems include major sand seas ergs in low lattitude and mid latitude arid regions pleistocene carbonate and holocene modern siliciclastic coastal systems the sedimentary record of most modern aeolian systems remains largely unknown the majority of palaeoenvironmental reconstructions of aeolian systems envisage transverse dunes whereas successions representing linear and star dunes remain under recognized research questions that remain to be answered include i what factors control the preservation potential of different types of aeolian bedforms and what are the characteristics of the deposits of different bedform types that can be used for effective reconstruction of original bedform morphology ii what specific set of controlling conditions allow for sustained bedform climb versus episodic sequence accumulation and preservation iii can sophisticated four dimensional models be developed for complex patterns of spatial and temporal transition between different mechanisms of accumulation and preservation and iv is it reasonable to assume that the deposits of preserved aeolian successions necessarily represent an unbiased record of the conditions that prevailed during episodes of earth history when large scale aeolian systems were active or has the evidence to support the existence of other major desert basins been lost for many periods throughout earth history

a new species of zangerlia testudines nanhsiungchelyidae from the upper cretaceous redbeds at bayan mandahu inner mongolia and the relationships of the genus zangerlia neimongolensis sp nov is described on the basis of material from the upper cretaceous redbeds at bayan mandahu in inner mongolia zangerlia neimongolensis is similar to zangerlia testudinimorpha in the proportions of the carapace and plastron and presence of a knob at the posterior end of the neural series but differs from it in the arrangement of scutes covering the bridge the placement of zangerlia in the nanhsiungchelyidae is supported by derived features of the bridge peripherals and plastral scutes shared by z neimongolensis basilemys and nanhsiungchelys these are the presence of ventrally expanded sixth inframarginal scutes humeral scutes that are narrow at the midline and expanded laterally pectoral scutes that are wide at the midline and narrow laterally and large rectangular abdominal scutes the skull of zangerlia is more primitive than that of nanhsiungchelys the only other member of the family for which a skull is known it shows extensive emargination of the temporal and

a bloat and float taphonomic model best explains the upside down preservation of ankylosaurs abstract it is widely held that within the cretaceous fluvial and marine deposits of north america ankylosaur remains are typically preserved upside down however this anecdotal observation has yet to be substantiated likewise none of the various hypotheses that purport to explain the frequent occurrence of overturned ankylosaurs has been tested either this study is the first to apply quantitative and modeling approaches to address these shortcomings we find strong statistical support for the dominance of upside down occurrences and favour a bloat and float model to account for them according to this model ankylosaur carcasses become reworked into fluvial or marine settings where they bloat and overturn prior to their final deposition differential floating behaviour between ankylosaurids and nodosaurids may have implications regarding the occurrence of the latter in marine depositional environments this consideration of ankylosaur taphonomy might similarly help to explain the purported frequency of overturned glyptodonts which share a similar bauplan with ankylosaurs

characteristics of marine seismic survey sounds in the beaufort sea geophysical survey vessels emit very intense pulses of underwater sound at intervals of several seconds these noise pulses are sometimes detectable at very long ranges sound pulses from geophysical surveys were recorded in shallow parts of the beaufort sea during august and september of 1980 1984 hydrophones deployed from a quiet boat were the primary sensors but aircraft deployed sonobuoys were also used water depths for the boat recorded data were 9 130 m but mostly 4 km best fit equations for maximum rms received levels in db generally were obtained by assuming cylindrical spreading 10 log range and a term linear in range corresponding to an absorption loss or scattering term the coefficients of the linear term va

trace fossils from marginal lacustrine deposits of the cretaceous jinju formation southern coast of korea abstract trace fossils from the cretaceous jinju formation of the south coast of korea occur in interbedded medium to fine grained sandstone of a moderate energy lake shoreface and mudstone shales of a periodically exposed low energy shallow lake and interfingerings of both of the above the trace fossils are represented by beaconites antarcticus beaconites coronus cochlichnus anguineus diplichnites octopodichnus cf didactylus diplichnites type a diplichnites isp helminthopsis hieroglyphica palaeophycus sulcatus palaeophycus tubularis planolites annularis planolites beverleyensis protovirgularia dichotoma skolithos magnus taenidium barretti and sauropod tracks the diplichnites specimens are among the first arthropod trackways recorded from the cretaceous two of the four trackway bearing ichnocoenoses present in the study area are considered representative of composite ichnofacies sinusoidal burrows or trails and simple irregular interface burrows or trails probably formed in wet possibly submerged soupground softground conditions in low or medium energy lake margins and represent the mermia ichnofacies trackways and meniscate burrows probably formed on the subsequently subaerially exposed lake margins following lake regression and represent an overprinting by the scoyenia ichnofacies the other two trackway bearing ichnocoenoses are from the scoyenia ichnofacies alone

the occurrence of psittacosaurus xinjiangensis sereno and chow 1988 in the urho area junggar basin xinjiang people s republic of china a partial specimen of psittacosaurus xinjiangensis from the urho locality in the western junggar basin china extends the known geographical range of p xinjiangensis and documents the adult morphology in this species variation in the number of denticles on the dentary tooth crowns is documented possibly representing a decrease in the number of denticles during growth although a high denticle count remains a diagnostic feature of the species

the age of the dinosaur bearing sediments at tebch inner mongolia people s republic of china the coarsening upward clastic sequence at tebch inner mongolia china containing the dinosaur psittacosaurus mongoliensis comprises the remains of a fluviolacustrine system deposited in an extensional tectonic setting the presence of asteropollis sp cf asteropollis trichotomosulcatus singh singh 1983 in conjunction with the absence of tricolpate pollen indicates a barremian or possibly early aptian age the overlying tebch basalt dated by the 40ar 39ar laser step heating method yields a mid aptian age of 110 0 52 ma this chronology supports the argument that the juifotang formation of the jehe group in western liaoning is early cretaceous with the jurassic cretaceous boundary very low within or below the base of the jehe group our data also suggest that the berriasian hauterivian neocomian age suggested for the one known russian locality that has yielded p mongoliensis shestakovskaya svita at gorno altayaskaya avtonomnaya oblast may be excessively old

the averno 2 fissure eruption a recent small size explosive event at the campi flegrei caldera italy the averno 2 eruption 3 700 50 a b p was an explosive low magnitude event characterized by magmatic and phreatomagmatic explosions generating mainly fall and surge beds respectively it occurred in the western sector of the campi flegrei caldera campanian region south italy at the intersection of two active fault systems oriented ne and nw the morphologically complex crater area largely filled by the averno lake resulted from vent activation and migration along the ne trending fault system the eruption generated a complex sequence of pyroclastic deposits including pumice fall deposits in the lower portion and prevailing surge beds in the intermediate upper portion the pyroclastic sequence has been studied through stratigraphical morphostructural and petrological investigations and subdivided into three members named a through c member a was emplaced during the first phase of the eruption mainly by magmatic explosions which generated columns reaching a maximum height of 10 km during this phase the eruption reached its climax with a mass discharge rate of 3 2 106 kg s intense fracturing and fault activation favored entry of a significant amount of water into the system which produced explosions driven by variably efficient water magma interaction these explosions generated wet to dry surge deposits that emplaced member b and c respectively isopachs and isopleths maps as well as areal distribution of ballistic fragments and facies variation of surge deposits allow definition of four vents that opened along a ne oriented 2 km long fissure the total volume of magma extruded during the eruption has been estimated at about 0 07 km3 dre the erupted products range in composition from initial weakly peralkaline alkali trachyte to last emplaced alkali trachyte isotopic data and modeling suggest that mixing occurred during the averno 2 eruption between a more evolved less radiogenic stored magma and a less evolved more radiogenic magma that entered the shallow reservoir to trigger the eruption the early phases of the eruption during which the vent migrated from sw to the center of the present lake were fed by the more evolved uppermost magma while the following phases extruded the less evolved lowermost magma integration of the geological and petrological results suggests that the averno 2 complex eruption was fed from a dyke shaped shallow reservoir intruded into the ne sw fault system bordering to the west the la starza resurgent block within the caldera floor

basilochelys macrobios n gen and n sp a large cryptodiran turtle from the phu kradung formation latest jurassic earliest cretaceous of the khorat plateau ne thailand

bee cell trace fossils associations on paleosols from the santa cruz formation palaeoenvironmental and palaeobiological implications abstract numerous isolated fossil bee cells and other trace fossils are documented from the santa cruz formation santa cruz argentina the trace fossils are described from paleosols of 7 coastal localities the paleosols are composed of massive to laminated claystone to siltstone or massive to diffuse laminated very fine tuff and reworked tuff they are poorly developed but include rich trace fossils and root traces assemblages the isolated bee cells n 47 are barrel to oval shaped with one end rounded to flattened and the other flattened they lack discrete walls and antechambers but have a smooth lining they are ascribed to celliforma rosellii n 28 and to a new ichnospecie celliforma argentina n 19 the new ichnospecies differs from c rosellii on the shape of the inferior end of the chamber been the first rounded to flattened and the c rosellii rounded to pointed resulting in a final barrel shape in c argentina and an oval shape in c rosellii c rosellii has an average length and width of 17 mm and 9 8 mm c argentina average length and width are 9 2 and 5 1 mm in some specimens of c rosellii below the basal mark in the cell the infill has a strong organic component that has been identified under sem this could indicate the exceptional preservation of the fluid deposited by the adult bee for the nutrition of the larva the trace fossils assemblage shows moderate diversity and abundance the ichnoassemblage recorded consist in celliforma rosellii celliforma argentina palaeophycus tubularis planolites beverleyensis feoichnus challa fictovichnus gobiensis taenidium barretti and a variety of root traces these trace fossils are considered to be part of a celliforma ichnofacies but with a scarce presence of calcareous components considering pedogenic features compositional aspects and ichnoasemblage a relatively warm semiarid subhumid and seasonal climate where herbaceous communities dominated can be established for the middle to upper interval of the santa cruz formation

first evidence for ultrahigh pressure garnet peridotite in the north american cordillera constraints on the thickness of mantle lithosphere involved in collisional orogenesis are fundamental for understanding the geodynamics of mountain building and the overall growth of continents by accretionary tectonics garnet peridotite and ultrahigh pressure uhp crustal rocks provide such a constraint in many collisional orogens but have hitherto been unrecognized in western north america s cordillera here we show the first evidence for exhumation of uhp 2 8 gpa garnet peridotite and eclogite and for deposition of these rocks as detritus in an early jurassic forearc basin laberge group yukon territory and british columbia our results suggest that collision in this part of the north american cordillera must have been thick skinned involving a proterozoic continental mass with a lithosphere 100 km and possibly to 150 km thick our discovery also provides insight into the vigor of uplift and erosion of deep seated rocks in a nascent continental arc

lithofacies and fluvial lacustrine environments of the palaeogene sevkhuul and ergil members ergiliin zoo formation south gobi mongolia the clastic sequence of the ergiliin zoo formation stretches along the mongolian chinese border in the southern gobi desert mongolia its members sevkhuul ergil exposed in the erdene sum region are well known for their vertebrate remains of late eocene and oligocene age based upon field work the continental red beds were subdivided into four units described as i prodelta mud sand flat ii delta front iii delta plain and iv calcretes all sub environments are in a fluvial lacustrine setting electronmicroprobe analysis in addition to conventional thin section examination was applied to shed some light on the complex mineral association made up of light minerals quartz plagioclase ternary feldspar orthoclase smectite illite rare palygorskite heavy minerals almandine pyrope solid solution series zoisite epidote s s s and abundant goethite and carbonate minerals calcite dolomite igneous rocks being exposed in the source area have contributed to the formation of carbonate minerals and mg bearing sheet silicates during diagenesis higher up on the delta plain transitional between distal alluvial and deltaic deposits fluids emerged from the distal alluvial fluvial deposits and formed calcareous duricrusts drawing conclusions from the rock colour the mineral assemblage and the palaeoecological data the climatic conditions may be described as alternating wet and dry seasons closely resembling those conditions of a modern savannah

a review of nonmarine turtles from the late cretaceous of alberta the late cretaceous of alberta preserves one of the most complete records of fossil turtles within a single geographic area in north america the cenomanian dunvegan formation contains the earliest record of the family trionychidae in north america the santonian milk river formation contains a minimum of ten taxa with adocus a small trionychid and a member of the solemydidae being the most abundant diversity remains high in the mid campanian judith river group the solemyidid last occurs in the basal beds of the judith river group a member of the macrobaenidae first occurs in the dinosaur park formation the uppermost formation in the judith river group turtles diversity is low in the late campanian lower horseshoe canyon formation and they are absent in the early maastrichtian upper horseshoe canyon formation diversity increases in the late maastrichtian scollard formation although it is much less than in the contemporaneous hell creek formation of montana two of the taxa present in the scollar

insect trace fossils in aeolian deposits and calcretes from the canary islands their ichnotaxonomy producers and palaeoenvironmental significance insect trace fossils from canary islands have been known and discussed since the beginnings of the last century the most common and widespread morphologies have been tentatively referred to the ichnogenera celliforma palmiraichnus or rebuffoichnus and attributed to bees coleopterans and locusts until now herein they are included in a new single ichnospecies rebuffoichnus guanche isp nov which can be distinguished from other ichnospecies by the presence of an antechamber r guanche are considered herein as coleopteran curculionidae or scarabaeidae pupation chambers this is supported by themostly horizontal orientation in soils ellipsoid shape dispersion of sizes and particularly the internal surface of the wall chamber that is completely smoothed even in both extremes in addition it is supported by the finding of one adult weevil in a similar trace fossil and palaeoenvironment of australia all these characters argue against their assignation neither to egg pods of a locust species nor to bee cells the latter also contradicted by the lack of spiral closure the wall of r guanche shows the same petrological features of those of the palaeosol in which specimens are found in those specimens found in aeolian deposits the wall is composed of sand grains similar to those found in the dunes or sand sheets the diversity of microfabrics found in calcretes is higher and depends on the calcrete hostrock and the degree of development of the calcretes in poorly developed calcretes the trace fossils reflect very well the calcrete hostrock whereas in more developed ones they usually show peloidal ooidal or laminar microfabrics these similarities indicate that in contrast to some previous reports insects utilised as building material that of the surrounding soil as expectable for a coleopteran pupation chamber lower numbers of r guanche are recorded in calcretes from the western canary islands where no aeolian deposits are present in contrast to the high densities in the aeolian deposits of the eastern islands coleopterans would first colonise thin soils with calcretes developed on basaltic or sedimentary rocks in young islands and later colonise dunes as they appear when the islands aged the widespread presence of calcretes aeolian deposits and trace fossils in the easternmost and older canary islands is driven by both the geological evolution of the islands and climatic conditions both the calcretes and pupation chambers formed during the relatively wetter periods within otherwise prevailing arid to semiarid conditions

extraordinary preservation in a new vertebrate assemblage from the late cretaceous of mongolia we report here a new locality ukhaa tolgod brown hills from the upper cretaceous of the gobi desert of mongolia which shows an unmatched abundance of well preserved vertebrate fossils including the highest concentration of mammalian skulls and skeletons from any mesozoic site in the main collecting area about 4 km2 recovered and uncollected articulated skeletons of thero pod ankylosaurian and protoceratopsian dinosaurs represent over 100 individuals specimens collected also include skulls many with associated skeletons of over 400 mammals and lizards skeletons including the first known skull of the bird mononykus and nest sites that preserve the first known theropod dinosaur embryos1 in contrast to other mesozoic localities the diversity and abundance of theropods mammals and lizards are unusually high the exceptional preservation of vertebrates from the red bed facies of the gobi upper cretaceous has been attributed to arid conditions2 4 possibly involving catastrophic death and burial during major sandstorms5 although fossils are found in fluvial facies at ukhaa tolgod high concentrations of excellent specimens in aeolian facies support the argument for rapid entombment in sand this contrasts with conditions for the terrestrial upper cretaceous in north and south america where accretionary preservation of fossils in fluvial deposits predominates

trace fossils on dinosaur bones from upper cretaceous eolian deposits in mongolia taphonomic interpretation of paleoecosystems in ancient desert environments abstract the formation processes of trace fossils including shallow to deep pits notches borings tunnels and channels particularly at the limb joints observed on the surfaces of velociraptor protoceratops ankylosaurid and bagaceratops skeletons from upper cretaceous eolian deposits in the gobi desert mongolia were investigated the median diameters of these structures ranged from 5 25 to 7 68 mm these structures were likely created by insects scavenging on dinosaur carcasses this interpretation is corroborated by the presence of burrows of a size similar to the trace fossils observed on the dinosaur bone surfaces at the same locality broad borings about 32 mm in diameter created by small mesozoic mammals have also been discovered on the ribs and scapulae of a protoceratops skeleton dinosaur skeletons found at two localities tugrikin shireh and khermeen tsav and two formations the djadokhta formation and barun goyot formation exhibited the same type of damage to the limb joints the high frequency of trace fossils at the limb joints suggests that small animals targeted the collagen in the joint cartilage of dried dinosaur carcasses as a source of nitrogen which was relatively scarce in the eolian environments of the gobi desert during the late cretaceous

the celliforma ichnofacies in calcareous paleosols an example from the late miocene cerro azul formation la pampa argentina abstract invertebrate trace fossils from the late miocene cerro azul formation la pampa argentina are described and compared with known paleosol ichnofacies the formation is a loess succession punctuated by numerous calcareous paleosols trace fossils were recovered from thirteen localities distributed in a wide latitudinal and longitudinal range within la pampa province paleosols from the northwestern localities display clastic dikes and pedogenic slickensides and are compared with calcic vertisols which are typical of strongly seasonal and semiarid climate paleosols from the remaining localities have a bt horizon with blocky or prismatic peds and can be compared with mollisols the depth to the bk horizon for all paleosols averages 0 54 m suggesting a mean annual precipitation of 450 mm 147 mm also pointing to semiarid climatic conditions during soil formation the trace fossil assemblage from the cerro azul formation is of low diversity and abundance and is typified by the presence of the insect trace fossils celliforma rosellichnus rebuffoichnus fictovichnus and teisseirei the ichnospecies recorded are celliforma germanica celliforma cf rosellii celliforma isp rosellichnus isp rebuffoichnus casamiquelai fictovichnus cf sciuttoi fictovichnus isp teisseirei barattinia taenidium barretti and cylindrical burrow fills these trace fossils along with attaichnus kuenzelii vertebrate burrows and medium sized rhizoliths described in previous works are considered comparable with the celliforma ichnofacies this ichnofacies is indicative of well drained calcareous paleosols developed under low vegetation coverage for the analyzed succession the vegetation was probably dominated by scrubs with minor participation of herbaceous plants coprinisphaera ispp including coprinisphaera lazai coprinisphaera murguiai and coprinisphaera isp showing a cementation similar to associated late miocene trace fossils were only recorded along with celliforma isp in two localities this trace fossil assemblage is comparable with the coprinisphaera ichnofacies suggesting dominance of herbaceous communities and wetter climate than those of the celliforma ichnofacies some specimens of uncemented coprinisphaera ispp were produced during post miocene times and are not considered as a part of the trace fossil assemblage of the cerro azul formation

djadokhta formation correlative strata in chinese inner mongolia an overview of the stratigraphy sedimentary geology and paleontology and comparisons with the type locality in the pre altai gobi because the bayan mandahu redbeds of inner mongolia share similar sedimentary facies and fossil assemblages with the djadokhta formation of pre altai gobi the two units are interpreted as stratigr

geodetic analysis of dike intrusion and motion of the magma reservoir beneath the summit of kilauea volcano hawaii 1970 1985 we use leveling and trilateration data collected on kilauea volcano to constrain the location of deformation sources caused by magma accumulation intrusion and eruption for the 13 inflationary epochs examined combinations of an expanding point source and one or two opening rectangular dislocations mimic inflation of the summit reservoir and formation of dike s respectively the combined model adequately accounts for the deformation data and is consistent with the seismicity observed during each epoch for 10 deflationary epochs however the data require only a contracting point source confidence in these results is gained by noting that locations of the sources of both inflation and deflation are coincident within the observed uncertainties of the data the function of network geometry and the inversion procedure it appears therefore that magma accumulation at kilauea volcano may be characterized by the growth of dikes during inflation of the summit reservoir drainage of the reservoir on the other hand is not accompanied by significant closure of dikes in contrast to previous studies e g fiske and kinoshita 1969 dvorak et al 1983 that do not include the dislocation or dike growth component of summit magma accumulation and concluded that the source of inflation migrates over a 5 km2 area we find that a single magmatic reservoir source accounts for data collected during all inflationary and deflationary epochs results which compare favorably with those obtained from the point ellipsoid model can be used to estimate the distribution of stresses within the volcano in the near field of the source

sineoamphisbaena hexatabularis an amphisbaenian diapsida squamata from the upper cretaceous redbeds at bayan mandahu inner mongolia people s republic of china and comments on the phylogenetic relationships of the amphisbaenia sineoamphisbaena hexatabularis wu et al 1993 is the earliest known amphisbaenian represented by well preserved cranial and postcranial material it reveals a mosaic of generalized lizard like features and amphisbaenian characters most distinctive of the latter are features of cranial consolidation adaptive for a fossorial way of life phylogenetic analyses strongly confirm the monophyly of the amphisbaenia inclusive of s hexatabularis the amphisbaenia is diagnosed by a suite of apomorphic characters the available evidence suggests a probable amphisbaenia macrocephalosauridae relationship within the scincomorpha this is supported primarily by the unique modifications of the palate and temporal region of the skull it is argued here that the amphisbaenia evolved in central asia during the cretaceous in response to the transition from a perennial lacustrine environment to a dry semiarid eolian environment the relatively primitive morphology indicates that s hexatabularis was not permanently subterranean the further derived modifications of later forms are associated with tunneling in an environment of more compact soils

monitoring and modelling hydrothermal fluid emission at la solfatara phlegrean fields italy an interdisciplinary approach to the study of diffuse degassing discharge of hydrothermal fluids at la solfatara is one of the many pieces of evidence testifying to the level of activity and the potential danger characterizing the volcanic complex of the phlegrean fields recent measurements of diffuse degassing shed light on the unexpected magnitude of this process and prompted further research to improve our understanding of the hydrothermal system feeding the surface phenomenon at la solfatara in this work we first present new data on co2 diffuse degassing that were collected during a campaign in july 2000 and confirm previous measurements of the degassing rate these data together with other information on subsurface structures and conditions provided the necessary constraints to perform physical modelling of the hydrothermal fluid circulation at la solfatara numerical simulations describe the ascent and evolution of a hot multi phase and multi component fluid composed of water and carbon dioxide through a homogeneous porous medium when certain system properties and conditions are used this model reproduces some of the main features which characterize the natural system including the energy budget associated with the ascent and condensation of hot fluids and the development of a single phase gas region whose existence was inferred from independent chemical data further simulations investigated the effects associated with changes in rock properties and fluid injection rates results showed that an increase in the permeability at shallow depth may have an important influence on the system conditions and fluid discharge they imply that surface phenomena accompanied by very high temperatures at shallow depths may survive long after deep feeding has ceased

statistical analysis of textural data from complex pyroclastic sequences implications for fragmentation processes of the agnano monte spina tephra 4 1 ka phlegraean fields southern italy the agnano monte spina eruption 4 1 ka generated pyroclastic deposits with complex internal stratigraphy that reflects variations in eruptive style to obtain constraints on the fragmentation processes we analysed grain size and scanning electron microscopy sem data by means of multivariate statistical techniques of the cluster and factor analysis types the results allow the identification of end member deposits related to either pure magmatic activity or pure phreatomagmatic activity in addition some deposits show evidence of the contemporaneous operation of both end member fragmentation modes the presence of the two contrasting fragmentation processes during the various phases of explosive activity is tentatively interpreted to be a function in inhomogeneities in gas exsolution processes within the magma column that feeds the eruption

significance of the 1982 2014 campi flegrei seismicity preexisting structures hydrothermal processes and hazard assessment we find that the double difference relocated seismicity which occurred over the last 30 years at campi flegrei was triggered by the uprising of fluids preferentially concentrated along onshore and offshore nw striking preexisting caldera faults focal volumes of the 2005 2014 seismicity do not overlap that of the 1982 1984 period when a major uplift of 1 8 m occurred in the central sector of the caldera this indicates a transition from an elastic to a plastic behavior due to fluid saturation and heating of the rocks in the hydrothermal reservoir the 2012 2014 deeper earthquakes are located in a low vp vs zone at the western boundary of the hydrothermal reservoir where a volume increase from a magmatic body at 3 5 km depth has been recognized the progressive rheological change from elastic to plastic in the upper 4 km of the crust implies that a slow upward migration of magma may not necessarily be preceded by earthquakes or swarms

new material of sinemys testudines sinemydidae from the early cretaceous of china sinemys lens is redescribed on the basis of new material from the early cretaceous of shandong china and a new species of sinemys from the ordos basin in inner mongolia is recognized sinemys and manchurochelys are placed in the sinemydidae sensu stricto on the basis of the derived features of a small first suprapygal and an elongate narrow posterior lobe of the plastron sinemys is autapomorphic in the absence of a cervical scute the entry of the first vertebral onto the anterior margin of the carapace the absence of a pygal bone the entry of the fifth vertebral scute into the posterior margin of the carapace in that the riblike lateral projections of the last three costal bones fit between the adjacent peripherals and in the isolation of the epiplastra from the hyoplastra by lateral expansion of the entoplastron sinemys gamera sp nov from the early cretaceous luohandong formation of the ordos basin inner mongolia is characterized by the presence of a flat carapace with an abbreviated poste

depositional environments and fades transitions of dinosaur bearing upper cretaceous redbeds at bayan mandahu inner mongolia people s republic of china campanian redbeds near bayan mandahu consist of six lithosomes which in turn comprise twelve lithofacies the distribution of these lithosomes along a 12 km escarpment resolves into three coeval paleogeographic zones representing a proximal to distal depositional gradient zone 1 the most proximal consists of alluvial lacustrine and eolian sediments it is interpreted as an eolian influenced distal alluvial fan or braid plain environment farther basinward zone 2 is dominated by structureless eolian sandstones and caliche profiles with minor occurrences of alluvial lacustrine and eolian dune deposits it is interpreted as a zone of vertically aggrading eolian sand stabilized by vegetation and a high water table zone 3 the most distal is dominated by eolian dune and structureless eolian deposits with lacustrine and interdune fluvial deposits it is interpreted as the southern margin of an eolian dune field that was dominated by transverse and barchan dunes u shaped mature caliche profiles ca

long term exhumation history of the inner mongolian plateau constrained by apatite fission track analysis the inner mongolian plateau along the southeastern flank of the wider mongolian plateau is a vast undulating surface ranging in elevation between 900 and 1500 m above sea level the peculiar topography of this area is assumed to be closely related to its complex tectono thermal evolution since late paleozoic the lithospheric structure of the plateau includes three continental blocks the mandula and the bart obo blocks form the southern margin of the central asian orogenic belt in that area and to the south the plateau includes the northern margin of the north china craton apatite fission track aft ages and track length distributions from 13 basement outcrops situated in the main tectonic blocks forming the inner mongolian plateau were determined in order to reconstruct its denudation history the thermal histories inferred from these data imply multi phased differential exhumation burying processes from the late paleozoic to the early cretaceous this complex thermal history is largely related to the early middle triassic closure of the paleo asian ocean the jurassic closure of the mongol okhotsk ocean and the early cretaceous orogenic collapse of the mongol okhotsk belt finally since late cretaceous no further major tectonic movement occurred and the inner mongolian plateau has been largely peneplained

mechanical and thermo fluid behaviour during unrest at the campi flegrei caldera italy abstract the campi flegrei caldera cfc is a resurgent nested structure resulting from the two main collapses of the campanian ignimbrite 37 ka and the neapolitan yellow tuff 12 ka eruptions while the whole structure is affected by a broad subsidence ongoing local resurgence and unrest occur inside the young nested caldera structure the caldera has shown signs of unrest during the past 30 years with two uplift events that have generated a net displacement of 3 5 m each followed by subsidence the time evolution of both ground deformation and seismicity recorded in campi flegrei in the last 30 years since 1969 up to the present shows aspects not completely explainable by means of mechanical models in particular the occurrence of an intense seismic activity during uplift and its absence during subsidence lead us to infer that these two phases might be related to two variable mechanisms the large amount of magma and the shallow convective fluids circulation needed to explain the very high temperature gradient 100 c km measured also in marginal areas of the caldera suggest the presence of a thermo dynamical system in supercritical conditions we have carried out an analysis of the unrest episodes by means of 3d finite element method simulating the mechanical and fluid dynamical response of a two phase medium solid fluid to a sudden stepwise pressure or volume increase at a depth of 4 km according to geological and geophysical constraints in our scheme we have subdivided the caldera floor into a central and a peripheral zone the central zone represents the resurgent block and has high permeability while the peripheral zone is less permeable we have performed a parametric analysis assuming both young modulus and permeability of each zone as variables the basic test for each solution was how well it simulates the time evolution of ground deformation during the last unrest episode 1982 1984 the results obtained clearly show that fluids diffusion accounts for some peculiar features of the ground deformation such as the variable behavior between the resurgent block and the peripheral part of the caldera floor subsidence is explained in terms of lateral diffusion of fluids instead of a regression of source processes consequently no variation of shear stress occurs during this phase providing a physical explanation to the absence of seismicity

a three dimensional qp imaging of the shallowest subsurface of campi flegrei offshore caldera southern italy to improve the knowledge of the shallowest subsurface of campi flegrei caldera a 3 d p wave attenuation tomography of the area was performed we analyzed about 18 000 active seismic traces which provided a dataset of 11 873 t measurements e g the differential traveltimes to quality factor ratios these were inverted through an adapted tomographic inversion procedure the 3 d tomographic images reveal an average qp about 70 interpreted as water saturated volcanic and marine sediments an arc like low qp structure at 0 5 1 km depths was interpreted as a densely fractured fluid saturated rock volume well matching the buried rim of campi flegrei caldera the spatial distribution of high and low qp bodies in the inner caldera is correlated with low vp values and may reflect either the differences in the percentage of fluid saturation of sediments or the presence of vapor state fluids beneath fumaroles manifestations

elastic deformation models of krafla volcano iceland for the decade 1975 through 1985 the dynamics of the shallow magma reservoir at krafla volcano in ne iceland have been analyzed with three types of elastic models based on over 70 surveys of tilt and displacement made from 1975 to 1985 a period of continuous volcano tectonic activity modeling results are integrated with geophysical and geological information to estimate the position geometry and volume change of magma reservoir domains subjected to periodic inflation and deflation dominating influences on magma reservoir dynamics are examined in the context of activity in krafla s associated rift system and the deformation of its caldera from 1975 1985 rather than the fluid filled cavity concept of mogi 1958 and most recent workers our models are idealized as strained regions with spherical double spherical or general ellipsoidal symmetry the models are mathematically generalized from that of mogi 1958 and are derived by inversion of displacements model results from different displacement components are remarkably consistent although models based on vertical displacements typically have errors of fit much closer to expected measurement errors than those based on tilt or horizontal displacements about one half of the double sphere and ellipsoid models have significantly better fits than single sphere models double sphere model results are consistent with a 2 to 3 km center to center separation of magma storage zones from at least 2 km to 4 km depth by portions of the fissure system as implied by s wave attenuation patterns for 1976 1977 however all models suggest pressurization zones of more limited extent than possible domains of storage inferred from s wave attenuation ellipsoid models typically implied unrealistically shallow depths of magma storage caldera inflation rates decreased after january 1978 when the caldera periodically reinflated to its level prior to the initial december 1975 deflation event from 1975 1980 the volume and duration of inflation between deflation events was strongly correlated with the volume of the previous deflation after 1980 there was a significant increase in the duration of inflation periods and a decrease in rates of caldera inflation and fissure system widening consistent with these results the magma reservoir is conceptualized as a hot rock mass containing numerous magma chambers and pressure sensitive conduits connecting the chambers and deep magma sources magma is injected into the fissure system at critical pressures determined by the confining stress and rock mass strength the duration and volume of inflation required to reach a critical pressure threshold is largely dependent on the volume of magma released in the previous deflation reduction of the extension rate across the krafla fissure system after 1980 suggests that extensional forces were also reduced a resultant rise of confining pressure on the magma reservoir and a reduced capacity of the fissure system to accommodate dike injection in combination would have increased critical stress levels for reservoir deflation and reduced the pressure gradient driving magma supply from deep sources

new material of xinjiangchelys reptilia testudines from the late jurassic qigu formation shishugou group of the pingfengshan locality junggar basin xinjiang the late jurassic qigu formation of the shishugou group in the pingfengshan locality contains a vertebrate fauna dominated by two taxa of turtles both members of the genus xinjiangchelys one of these xinjiangchelys latimarginalis young and chow 1953 is well represented by a series of specimens the second is specifically indeterminate and is represented by only a single fragmentary specimen but is distinctive in having a long narrow plastral lobe derived features of xinjiangchelys that separate it from plesiochelys include the presence of a loose connection between the plastron and carapace with pegs on the plastron fitting in sockets on the peripherals the extension of the pleural marginal sulcus onto costals one to five the dorsal thickening of the lateral edges of peripherals two to seven the highly expanded seventh to eleventh peripherals the extension of the anal scute to the hypoplastron xiphiplastron suture or onto the hypoplastron a reduction in length of the first dorsal rib and the

insect trace fossils in pleistocene deposits from the pityusic islands balearic archipelago western mediterranean ichnotaxonomy and palaeoenvironmental significance abstract insect trace fossils attributable to the celliforma ichnofacies rebuffoichnus casamiquelai and palmiraichnus castellanosi are recorded from the pleistocene deposits of nine sites from the pityusic islands these deposits characterized by aeolian and colluvial strata interbedded with two types of palaeosols with a high amount of trace fossils show a strong relationship with environmental changes occurred during the pleistocene the celliforma ichnofacies is typical of well drained palaeosols with low vegetation indicating semiarid to sub humid conditions according to the abundance of ichnospecies in each type of palaeosol palmiraichnus castellanosi indicates that bees preferred to nest in wetter conditions whereas rebuffoichnus casamiquelai indicates that coleopterans could live under drier conditions even in this case when its abundance is relatively high within periods with increased rainfall

broadband spectra of seismic survey air gun emissions with reference to dolphin auditory thresholds acoustic emissions from a 2120 cubic in air gun array were recorded through a towed hydrophone assembly during an oil industry 2 d seismic survey off the west wales coast of the british isles recorded seismic pulses were sampled calibrated and analyzed post survey to investigate power levels of the pulses in the band 200 hz 22 khz at 750 m 1 km 2 2 km and 8 km range from source at 750 m range from source seismic pulse power at the 200 hz end of the spectrum was 140 db re 1 pa2 hz and at the 20 khz end of the spectrum seismic pulse power was 90 db re 1 pa2 hz although the background noise levels of the seismic recordings were far in excess of ambient due to the proximity of engine propeller and flow sources of the ship towing the hydrophone seismic power dominated the entire recorded bandwidth of 200 hz 22 khz at ranges of up to 2 km from the air gun source even at 8 km range seismic power was still clearly in excess of the high background noise levels up to 8 khz acoustic observations of common dolphins during preceding seismic surveys suggest that these animals avoided the immediate vicinity of the air gun array while firing was in progress i e localized disturbance occurred during seismic surveying although a general pattern of localized disturbance is suggested one specific observation revealed that common dolphins were able to tolerate the seismic pulses at 1 km range from the air gun array given the high broadband seismic pulse power levels across the entire recorded bandwidth and known auditory thresholds for several dolphin species we consider such seismic emissions to be clearly audible to dolphins across a bandwidth of tens on kilohertz and at least out to 8 km range

the restless resurgent campi flegrei nested caldera italy constraints on its evolution and configuration abstract we have collected new stratigraphic data in the campi flegrei caldera through surface geological mapping and study of cores drilled to various depths we integrate these data with geological geochronological and geophysical constraints available in the literature to reconstruct the volcanic and deformational history of the caldera the caldera is a resurgent nested structure resulting from two main collapses related to the campanian ignimbrite 37 ka and the neapolitan yellow tuff 12 ka eruptions while the structure is affected by a broad subsidence ongoing local resurgence and unrest occur inside the younger nested caldera structure although most of the caldera floor consists of multiple structural blocks due to long term deformations magmas were able to erupt only in one sector of the resurgent part the caldera has shown signs of unrest during the past 25 years with short term deformations that have generated a net uplift of 3 5 m the short term deformations are related to the neapolitan yellow tuff caldera resurgence and interpreted as the net result of brittle and ductile components the long term deformations likely represent the sum of the permanent brittle component of each short term deformational event

systematics and taxonomic diversity of squamates from the upper cretaceous djadochta formation bayan mandahu gobi desert people s republic of china squamate fossils collected for the sino canadian dinosaur expeditions 1986 1990 include some 70 specimens from the upper cretaceous campanian djadochta formation exposed at the vicinity of bayan mandahu inner mongolia china well preserved skulls jaws postcranial skeletons and even osteodermal armor document a fossil assemblage composed of at least 18 genera in 8 families besides showing considerable taxonomic diversity several families recorded in the assemblage are of importance in understanding the geologic and biogeographic distribution of the relevant groups and the paleoenvironment in which these lizards lived comparison of the gobi lizard assemblage with north american and central asian assemblages is briefly discussed taxonomic differences in the assemblage from that of the upper cretaceous in the north american western interior reflect endemism and suggest a low frequency of interchange of small terrestrial vertebrates between the two regions during campanian time the taphonomic s

the effect of collapse structures on ground deformations in calderas ground deformations related to unrest episodes in calderas are generally interpreted like in other volcanic environments in terms of increased pressure within a magma chamber embedded in a continuous elastic medium in this framework the depth of the pressure source is inferred from the size of the deformed area this scheme works quite well for individual volcanoes for instance hawaiian shields where a good correspondence between inflation events and eruptive episodes has been observed ground deformation in calderas however show unusual features that are difficult to interpret within such a scheme because considerable positive deformation in the order of several meters and microfracturing i e intense seismicity may occur without eruptions altough the estimated depth for the magma source is sometime very shallow less than 1 2 km it has been recently suggested that the contact zones at the border of collapsed calderas could act as stress strain discontinuity zones and thus bias modeling results obtained for continuous elastic media we use both observations and theoretical modeling based on 3 d finite element techniques to show that ground deformations in collapsed calderas are strongly influenced by the caldera structure giving a new perspective in related geological and geophysical observations in such areas

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

introduction to the special issue commemorating the 30th anniversary of the royal tyrrell museum of palaeontology with a summary of the museum s early history and its research contributions located just west of drumheller in southern alberta canada the royal tyrrell museum of palaeontology rtmp is nestled among outcrops of the upper cretaceous horseshoe canyon formation exposed along the red deer river valley fig 1 since it officially opened on 25 september 19851 the museum has become one of alberta s must see tourist attractions a significant contributor to the local economy and earned an international reputation for the quality of its palaeontological collections and the research conducted by its scientists the rtmp is unique within canada in being the only government supported museum dedicated to palaeontology and it is one of the few such institutions in the world fig 1 the royal tyrrell museum of palaeontology a front of museum and main entrance circa 2010 looking westwards and with horizontal beds of the upper cretaceous horseshoe canyon formation exposed in the walls of the red deer river valley in the distance b aerial photograph oblique angle and looking to the north northeast the museum sits on top of the number 7 coal seam sensu gibson 1977 and at the base of the horsethief member of the horseshoe canyon formation d a eberth pers comm 2015 that stratigraphic position correlates with an age of about 71 5 ma i e late campanian and lies within the upper part of the edmontosaurus regalis pachyrhinosaurus canadensis dinosaur assemblage zone see eberth et al 2013 fig 6 c the iconic running theropod logo that until recently graced the exterior of the museum below a life sized tyrannosaurid sculpture by brian cooley one of many such sculptures by cooley that have been featured at the museum since its opening in 1985 and with the education wing opened in 2003 as the atco tyrrell learning centre in the background d the cretaceous alberta life sized diorama opened in 2007 an example of a rtmp exhibit that relies heavily on discoveries and interpretations by museum researchers in this case work done in the albertosaurus bonebed and at other localities throughout the horseshoe canyon formation all photographs courtesy of the royal tyrrell museum of palaeontology this special issue of the canadian journal of earth sciences presents a collection of papers commemorating the rtmp s 30th or pearl anniversary our rationale for doing a 30th anniversary volume was two fold first it is an opportunity to showcase the breadth of research conducted by current and former museum scientists as well as by some colleagues having a history of collaboration with the rtmp the 13 invited papers included in this volume are a mix of review and original research papers all thematically focused on the geology and palaeontology of alberta to varying degrees each contribution is the result of work supported by the rtmp and relies on specimens housed in the museum s collections second the 30th anniversary is an opportunity to reflect on the rtmp s history and its research program as is typical for most institutions the rtmp has done little to formally document its own history this year likely will be the last major milestone for which the original generation of museum staff are still working and available to share their recollections about the museum fieldwork and research already deaths and departures have winnowed away part of the original

protoceratopsian embryos from inner mongolia people s republic of china new protoceratopsid fossils from bayan mandahu include the smallest specimens of protoceratops and bagaceratops recovered to date none of these specimens were found associated with dinosaur eggshe

modelling gravity variations consistent with ground deformation in the campi flegrei caldera italy abstract in recent years 1970 72 and 1982 84 two inflation episodes took place in the campi flegrei caldera italy characterized by significant ground uplift and gravity variations an elastic half space model with vertical density stratification is employed to compute the displacement field and the gravity variations produced by the deformation of buried layers following the inflation of a spherically symmetric deformation source contributions to gravity variations are produced by dilation contraction of the medium by the displacements of density interfaces the free surface and subsurface layers and of source boundaries and possibly by new mass input from remote distances into the source volume three cases were examined in detail in case i the magma chamber is identified as the deformation source and volume and pressure increase in the magma chamber is due to input of new magma from remote distances in case ii deformation is due to magma differentiation within the magma chamber deformation source with constant mass in case iii the geothermal system is identified as the deformation source and a pressure increase possibly driven by the exsolution of high temperature and high pressure volatiles in the magma chamber is assumed to play a dominant role from the comparison between measured and computed gravity residuals free air corrected gravity variations we can assess that in case i an inflation source with constant density would predict gravity residuals compatible with observations whereas an expansion at constant mass case ii would predict gravity residuals much lower than observed the resolving power of gravity data however prevents accurate assessment of the density of the emplaced material in case iii the pervasive density increase of the geothermal fluids induced by pressure increase is assumed to be the main source of gravity variations the average porosity value required for this model to match both the ground deformation and the gravity residuals is found to be 10 a value which is compatible with measured porosity values at campi flegrei in deep wells the subsidence phases following both inflation episodes and the gravity residuals during subsidence lead us to consider case iii as more plausible even if a suitable combination of cases i and iii cannot be discarded

p sv conversions at a shallow boundary beneath campi flegrei caldera italy evidence for the magma chamber seismograms from an active seismic experiment carried out at campi flegrei caldera near naples italy show a large amplitude 5v polarized shear wave following by less than 1 5 s p waves reflected at wide angle from a deep crustal interface early arriving sv polarized waves with the same delay to direct p waves are also observed in seismograms from a regional 280 km deep magnitude 5 1 earthquake such short delays of s to p waves are consistent with a p sv conversion on transmission occurring at a shallow boundary beneath the receivers the large amplitude of the converted sv phase along with that the p waves are near vertical requires a boundary separating a very low rigidity layer from the upper caldera fill the converted phases are interpreted as a seismic marker of a magma chamber the top of this magma chamber is located slightly deeper than the deepest earthquakes observed during the 1982 1984 unrest of campi flegrei

early diagenetic stabilization of trace elements in reptile bone remains as an indicator of maastrichtian late paleocene climatic changes evidence from the naran bulak locality the gobi desert south mongolia abstract maastrichtian dinosaur bone remains from the naran bulak locality the gobi desert with well preserved bone textural features are enriched in some trace elements primarily in ree these features of vertebrate fossils were formed during diagenesis following rapid burial in mudflow sediments and prior to postfossilization epigenetic changes trace elements are mainly concentrated in diagenetic apatite their contents in the bones correlate with that in their enclosing sediments for both maxima and minima fossil and sediment compositions were established under the influence of paleoclimate they are correlated with long term climatic changes with the aridity maximum at the k t boundary climatic changes were recorded via the change of salinity of waters interacting with the buried vertebrate remains

an azhdarchid pterosaur eaten by a velociraptorine theropod tooth marked bones are more common in the fossil record than published accounts would lead us to believe but with rare exceptions the animals that made the marks cannot be identified a partial s

lithostratigraphy and depositional environments of the upper cretaceous djadokhta formation ulan nuur basin southern mongolia and its paleoclimatic implication abstract non marine upper cretaceous strata are widely distributed in the gobi basin of southern mongolia and record marked paleoenvironmental and paleoclimatic changes the climate in this region is considered to have changed from humid during the cenomanian to santonian to semi arid during the campanian and returned to humid during the early maastrichtian the change from humid to semi arid climate is well recorded in the djadokhta formation as former division in the ulan nuur basin of the central gobi basin in previous studies the djadokhta formation was formally regarded as being characterized by eolian deposits formed under a semi arid climate however the present study revealed that this formation comprises sub humid fluvial lithofacies in the lower part and semi arid eolian lithofacies in the upper part since the djadokhta formation was initially defined as a succession characterized by eolian lithofacies it is proposed here that the lower part showing fluvial lithofacies should be separated from the djadokhta formation and is newly named as the alagteeg formation the alagteeg formation is characterized by alternating beds of horizontally bedded sandstone and mudstone indicating sandy braided river flood plain and ephemeral lake environments under sub humid climate the djadokhta formation revised division is further subdivided into two parts the lower part is composed of large scale cross stratified sandstone in situ and reworked calcretes and thick mudstone lens suggesting desert environments of broad sand dune fields with few inter dune ephemeral river and pond deposits under semi arid climate on the other hand the upper part comprises structureless sandstone with mature in situ calcretes exotic pebbly sandstone and large sized burrows these lithofacies imply steppe environments with calcic soil development under semi arid climate this change from sub humid to semi arid climate during the campanian is recorded not only in the ulan nuur basin but also in other regions of southern mongolia as well as northern china hence the broad aridification in the mid latitudes of the asian interior during the campanian is inferred

the neapolitan yellow tuff a large magnitude trachytic phreatoplinian eruption eruptive dynamics magma withdrawal and caldera collapse the results of a detailed stratigraphical and volcanological study has allowed the definition of the neapolitan yellow tuff nyt as the largest known trachytic phreatoplinian eruption with an estimated volume of not less than 30 km3 dre the nyt sequence can be subdivided in a lower and an upper member sedimentological and textural variations in time and space indicate that different eruptive and depositional mechanisms operated during the eruption the lower member eruptive phase was characterized by alternating phreatoplinian and magmatic explosions while the upper member eruptive phase was characterized by a random sequence of phreatomagmatic and magmatic explosions particles produced by the same explosion were deposited contemporaneously by fallout and surge mechanisms either at different or at the same distance from the vent compositional variations show that the nyt sequence cannot be modeled as an inverted compositionally zoned magma body with magma becoming more basic in the course of the eruption the chamber composed of three geochemically distinct magma layers was tapped at different depths according to the eruption dynamics each phreatoplinian explosion tapped concurrently all the magma layers while magmatic explosions tapped only one of them the onset of the nyt caldera collapse is well constrained between lower and upper member eruptive phases the collapse which is only gravimetrically detectable occurred inside the larger phlegrean fields caldera which therefore can be defined as a nested caldera

the present state of the magmatic system of the campi flegrei caldera based on a reconstruction of its behavior in the past 12 ka abstract new geochemical and sr isotope data have been acquired on samples representative of volcanic units erupted inside the resurgent campi flegrei caldera cfc over the past 12 ka these data integrated with previous published petrological and with newly acquired geochronological volcanological and geothermal data shed light on the nature and timing of the processes that controlled the evolution of the phlegraean magmatic system in the past 12 ka three isotopically and geochemically distinct magmatic components were erupted at the cfc as either homogeneous or mixed magma batches one component campanian ignimbrite component cic 87 sr 86 sr 0 70735 0 70740 is similar to the trachytic magma extruded during the first phase of the campanian ignimbrite ci eruption 37 ka a second component neapolitan yellow tuff component nytc 87 sr 86 sr 0 70750 0 70757 is similar to the latitic alkali trachytic magma batches extruded during the course of the neapolitan yellow tuff nyt eruption 12 ka a third component minopoli component mic 87 sr 86 sr 0 7086 is similar to the trachybasaltic magma of the minopoli 2 mi eruption 9 7 ka these components were erupted as either single batches of magma or mixed ci nyt or mi nyt batches of magma through vents located either along the structural boundary of the nyt caldera or inside the nyt caldera mainly on portions of the resurgent block under extensional stress the ci and nyt components represent residual portions of older large volume magma reservoirs which have fed eruptions since about 60 and 15 ka respectively the least evolved mi component was erupted only during the 12 9 5 ka and 8 6 8 2 ka epochs of activity through vents located on a ne sw regional fault system this component could represent a deeper reservoir tapped by the ne sw regional fault system reactivated after the nyt caldera collapse deeper mi and shallower ci and nyt magmatic systems interacted by mixing among batches of magma during their rise to surface overall the data suggest that the cfc magmatic system today is characterized by the presence of two larger independent reservoirs filled by residual portions of the ci and nyt magmas these generated many smaller shallower pockets of evolved magma that fed most of the eruptions that occurred in the cfc over the past 12 ka moreover a deeper reservoir mi tapped by the ne sw regional fault system provided batches of less evolved magma that mixed with magma present in the shallower pockets

depositional and erosional signatures in sedimentary successions on the continental slope and rise off prydz bay east antarctica implications for pliocene paleoclimate abstract the prydz bay region of antarctica is the immediate recipient of ice and sediments transported by the lambert glacier the single largest outflow from the east antarctic ice sheet the continental slope and rise provide records covering multiple glacial cycles and containing paleoclimatic information marine geological and geophysical data collected from the continental shelf and adjacent slope of prydz bay antarctica including seismic reflection data bathymetry and core records from odp drilling sites reveal the history of glacial sediment transport and deposition since the early pliocene times seismic facies are interpreted in terms of episodes of slope progradation contourite turbidite trough mouth fan and mass transport deposition two seismic units with estimated age of early to late pliocene and late pliocene to recent have been analyzed in detail for the area immediately offshore the lambert glacier and prydz bay and the adjacent mac robertson margin the upper slope is dominated by episodic mass transport deposits many of which accumulated to form a trough mouth fan since early pliocene times the trough mouth fan contrasts with the adjacent steep 4 6 continental slope of the mac robertson margin where glacigenic sediments have been transported down slope as high velocity turbidity currents via submarine channels the distal region exhibits evidence for contrasting effects of high energy traction dominated versus lower energy fallout dominated suspension flows the counter clockwise coriolis force modifies the erosion and deposition patterns of turbidity currents creating an asymmetric channel levee architecture since the early pliocene turbidite sedimentation surpassed the amount of sediment reworked and transported by westward flowing contour currents along the base of slope on the continental rise contourites and sediment waves were deposited in response to enhanced bottom water formation which is consistent with climatic cooling since late pliocene times this study based on existing seismic reflection and odp data highlights the need for a future scientific ocean drilling proposal on the prydz bay continental slope and rise in order to more accurately determine the timing of the important events that have influenced the evolution of this margin

a preliminary study of stress pattern at phlegraean fields as inferred from focal mechanisms thirty seven selected earthquakes which occurred in phlegraean fields from april to december 1983 are investigated from the focal mechanism point of view in order to attempt a preliminary representation of the stress pattern in the area from 37 earthquakes 15 reliable solutions were obtained ten mechanisms for events located around the solfatara crater are of tensional type 2 located in the gulf of pozzuoli seem to be compressive no predominant orientation ofp andt axes seem to occur evidently a more accurate analysis with a greater number of data in particular for compressive events is necessary in order to resolve a detailed map of stress pattern

oyu tolgoi mongolia siluro devonian porphyry cu au mo and high sulfidation cu mineralization with a cretaceous chalcocite blanket the oyu tolgoi porphyry cu au mo deposit is located in the gobi desert of southern mongolia the deposit consists of three main mineralized zones north central and south oyu interpreted to constitute at least two separate porphyry copper centers oyu tolgoi is associated with a series of small structurally controlled stocks and dikes of monzonitic and dioritic composition which intrude a sequence of siluro devonian volcanic and sedimentary rocks country rocks consist of pillow basalt and basaltic andesite interbedded with fine grained clastic sedimentary horizons the sequence is interpreted to have formed in a subaqueous island arc volcanic environment which formed part of the extensive paleozoic tuva mongol arc these island arc rocks are covered by carboniferous terrigenous sequences and are intruded by carboniferous syenite and granite and permian alkaline granite much of the area is covered by poorly consolidated cretaceous sedimentary sequences central oyu consists of a multiple phase hydrothermal breccia crosscutting an altered fine grained feldspar porphyry containing porphyry type alteration and mineralization the breccia underwent texture destructive advanced argillic alteration characterized by several associations of quartz alunite dickite pyrophyllite sericite and zunyite plus lesser svanbergite and fluorite these associations overprint earlier formed k silicate and quartz sericite illite assemblages copper mineralization at central oyu is present in a supergene chalcocite blanket that formed at the expense of a pyrite rich hypogene chalcocite covellite tennantite arsenosul vanite sulvanite chalcopyrite bornite sulfide suite that accompanied the advanced argillic alteration event at south oyu a feldspar hornblende porphyry of monzonitic composition intrudes a sequence of fine grained andesite and basaltic andesite hypogene copper gold mineralization occurs as early magnetite rich pyrite poor quartz chalcopyrite bornite stockworks and sheeted veinlets hydrothermal alteration is composed of biotite and k feldspar with apatite and minor albite magnetite averages 7 to 10 vol percent and copper and gold grades vary sympathetically these early assemblages are overprinted by a sericite chlorite event with ore grade copper and erratic gold and molybdenum values and also by structurally controlled pyrite rich advanced argillic alteration k ar ages show that the hypogene copper gold mineralization at south oyu is latest silurian earliest devonian 411 3 ma and that the entire district was intruded by postmineralization syenite during the carboniferous 307 4 ma the supergene chalcocite blanket at central oyu formed in the early cretaceous earliest late cretaceous based on ages for supergene alunite of 117 1 and 93 1 ma which makes central oyu one of the oldest preserved chalcocite blankets in the world chalcocite blanket preservation was favored by climatic desiccation into the late cretaceous and the tertiary it is inferred that significant regional uplift took place at the silurian devonian boundary this synmineral ization uplift and erosion may have been in part responsible for the telescoping of the hydrothermal systems at oyu tolgoi including the superposition of epithermal style associations over higher temperature deeper seated assemblages typical of the porphyry environment

quaternary laminar calcretes with bee nests evidences of small scale climatic fluctuations eastern canary islands spain thick laminar calcrete profiles are common on the surface of the eastern canary islands of lanzarote and fuerteventura this paper reports the study of one profile from lanzarote macher profile and one from fuerteventura tef a profile these profiles are about 2 m thick the macher profile is developed on basaltic host rocks and consists of two main horizons a lower horizon in which white veins of laminated micrite penetrate cracks and an upper laminar horizon the tef a profile is cumulative and consists from base to top of massive laminar and massive and laminar brecciated horizons highlighted in the study of these profiles are the presence of ooids the complex structure of the laminar horizons and the occurrence of fossil bee nests celliforma ooids consist of a nucleus of clay micrite and etched grains coated with envelopes of micrite and clay mainly palygorskite organic films favoured both the precipitation of carbonate and the adhesion of clays when the ooids formed in the soil the laminar horizons consist of a centimetre scale alternation of massive micrite with varied amounts of ooids and detrital grains with laminated micrite this alternation indicates the small scale periods of sedimentation erosion and soil formation in the upper part of a relatively stable surface these small scale alternations may reflect climatic vegetation changes in which arid periods are represented by micrite with ooids while laminated micrite reflects a better developed vegetation of the wet periods celliforma occur as ovoid larval cells with more or less rounded bases and a flat top the cells are about 3 cm long and 1 5 cm in diameter their wall is about 5 mm thick and is commonly laminated celliforma is interpreted as fossil nests of solitary bees their presence in the laminar horizon is evidence for the existence of a vegetation cover containing angiosperms

1980 1990 ten years of geochemical investigation at phlegrean fields italy abstract a systematic geochemical investigation on the thermal manifestations of the volcanic area of phlegrean fields started in 1980 with the aim of obtaining useful information about the changes possibly occurring at the same time of vertical ground movements termed as bradyseismic which frequently interested this area the attention was initially given to the fumaroles and the boiling pools of solfatara and pisciarelli then subsequently extended to thermal springs dug wells and crater lakes analytical data pertaining to a period preceding the last crisis of 1982 1984 were then available as well as other data collected during the previous crisis of 1970 a comprehensive picture of the variations observed before during and after the acceleration of vertical movement has been drawn according to the results obtained the intrusion of a magmatic body as the trigger of the observed ground deformation is considered unrealistic the whole area appears now in a quiet stage and no further perturbation is expected without previous significant tectonic activity chemical precursors appear suitable for an early detection of changes occurring at depth to forecast possible consequences to be expected in the surface environment