method of estimating the amount of in situ gas hydrates in deep marine sediments abstract the bulk volume of gas hydrates in marine sediments can be estimated by measuring interval velocities and amplitude blanking of hydrated zones from true amplitude processed multichannel seismic reflection data in general neither velocity nor amplitude information is adequate to independently estimate hydrate concentration a method is proposed that uses amplitude blanking calibrated by interval velocity information to quantify hydrate concentrations in the blake ridge area of the us atlantic continental margin on the blake ridge blanking occurs in conjunction with relatively low interval velocities the model that best explains this relation linearly mixes two end member sediments hydrated and unhydrated sediment hydrate concentration in the hydrate end member can be calculated from a weighted equation that uses velocity estimated from the seismic data known properties of the pure hydrate and porosity inferred from a velocity porosity relationship amplitude blanking can be predicted as the proportions of hydrated and unhydrated sediment change across a reflection boundary our analysis of a small area near dsdp 533 indicates that the amount of gas hydrates is about 6 in total volume when the interval velocity is used as a criterion and about 9 5 when amplitude information is used this compares with a calculated value of about 8 derived from the only available measurement in dsdp 533

discussion on shrimp u pb zircon dating of the exhumation of the lizard peridotite and its emplacement over crustal rocks constraints for tectonic models in this recent contribution nutman et al 2001 provide the first shrimp u pb zircon age data for the lizard peridotite and its immediate envelope and demonstrate the usefulness of ion microprobe geochronology in the unravelling of the complex thermo tectonic history inherent in the emplacement of such assemblages of plausibly oceanic rocks onto continental strata building on the research of cook et al 2000 the authors distinguish clearly between the lizard peridotite proper a mass of c 15 kbar mantle tectonite and the contiguous crousa downs complex of gabbro troctolite and sheeted mafic dykes emplaced into the peridotite following its exhumation and cooling thus although exhibiting many lithologies and structures characteristic of ophiolites the oceanic part of the lizard complex is clearly at least bipartite the studies of cook et al 2000 and nutman et al 2001 rationalize and clarify several problematic relationships in this extensively studied but still ambiguous suite we understand that the editorial handling of nutman et al s paper overlapped with the publication in this journal of our detailed account of the petrogenesis of the kennack gneiss which incorporates an evaluation of the tectonic context of this controversial unit on the basis of an idtims single zircon date sandeman et al 2000 we consider none the less that several aspects of the new contribution require comment these include nutman et al s interpretations of our earlier documentation of the petrology and age relationships of the kennack gneiss sandeman et al 1995 the man of war gneiss sandeman et al 1997 and the porthkerris plagiogranite clark et al 1998 b as well as our overview of the emplacement history of the lizard complex clark et al 1998 a an extended abstract cited but not referenced by nutman et al we employ herein the revised palaeozoic time scale of mckerrow

duration of the early cambrian u pb ages of volcanic ashes from avalon and gondwana volcanic zircons from three ashes give a u pb date of 511 1 ma on trilobite bearing upper lower cambrian upper branchian series strata of southern new brunswick that correlate into the siberian middle botomian toyonian stage interval this very young age on the late but not latest early cambrian of avalon is consistent both with a 519 1 ma age on the older caerfai bay shales of south wales that are tentatively correlated into strata with the oldest avalonian trilobites lower branchian and with a 517 1 5 ma age on the antatlasia gutta pluviae zone trilobites of morocco determination of a 522 2 ma zircon age on the moroccan subtrilobitic lower cambrian lie de vin formation is consistent with an earlier reported 521 7 ma age from the lie de vin but suggests that a 526 4 ma age on australian trilobite bearing lower cambrian rocks may be too old a 33 ma duration of the avalonian early cambrian and an 8 ma length of the avalonian trilobite bearing lower cambrian support proposals that

a u pb age for the cambrian taylor formation antarctica implications for the cambrian time scale abstract isotopic ages for the middle cambrian late cambrian are few because formations of the appropriate age combining diagnostic fossils and rocks datable by precise isotopic techniques are not common the taylor formation in antarctica includes carbonate units that host trilobites indicating an early late middle cambrian age volcanics below and above the trilobite bearing horizon yielded zircons that date the horizon at documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc newcommand cyr renewcommand rmdefault wncyr renewcommand sfdefault wncyss renewcommand encodingdefault ot2 normalfont selectfont declaretextfontcommand textcyr cyr pagestyle empty declaremathsizes 10 9 7 6 begin document landscape 505 1 pm 1 3 end document ma this age suggests that

thermotectonic evolution of the barrandian czech republic as revealed by apatite fission track analysis abstract a fission track ft study was carried out on apatite from upper proterozoic to upper carboniferous sedimentary and volcanic rocks in the barrandian czech republic apatite ft ages vary between 324 8 ma lower carboniferous and 196 14 ma lower jurassic mean confined track lengths range from 11 68 1 76 to 13 30 1 41 m the temperature time path of selected samples was simulated by applying the laslett annealing model and independent geological constraints from the barrandian the first stage of increased temperature that is recorded in nearly all samples occurred at the upper devonian lower carboniferous boundary the change in temperature is due to the thickening of the crust by increased sediment load and stacking of sedimentary rocks along thrusts ft data indicate a limitation of the extension of thrust sheets towards the west cooling during the carboniferous is attributed to exhumation of parts of the barrandian deposition of upper carboniferous to lower permian sediments caused a second increase in temperature in lower permian time variation in maximum temperature indicates variable thickness of the sedimentary cover the second cooling during the mesozoic is linked to the long term slow to medium exhumation process of the central variscan belt

reflection characteristics of linear carbon dioxide transition layers abstractseismic monitoring of underground co2 accumulations is a subject of growing interest in applied geophysics due to their large impedance contrasts attention is focused on accumulations of high co2 saturation in most cases however low saturation zones with dispersed carbon dioxide or saturation transition layers may have an important role in the propagation of waves within the reservoir giving rise to amplitude and phase changes of the seismic signals with this motivation we studied the reflectivity response of a simple reservoir model with a given co2 saturation depth profile on a theoretical basis we investigated the influence of the overall saturation vertical extent and spatial fluid distribution of a carbon dioxide transition zone in the reflectivity of a reservoir the parametric analysis entails the computation of the generalized p wave reflection coefficient and its variations with ray angle ava and frequency avf the combined analysis of ava and avf can help to characterize

sequence stratigraphy paleoclimate patterns and vertebrate fossil preservation in jurassiccretaceous strata of the junggar basin xinjiang autonomous region people s republic of china multi kilometre thick jurassic cretaceous age sedimentary successions exposed in the southern northwestern and northeastern regions of the junggar basin display a consistent and correlative stratigraphy comprising four stacked second order megasequences badaowan sangonghe shishugou and kalaza each consists of a basal erosional unconformity or discontinuity surface and lower middle and upper units that are interpreted as forestepping backstepping and aggradational systems tracts respectively each megasequence is interpreted as recording an upsection shift from active tectonism and uplift to tectonic quiescence with associated changes in crustal response and sediment supply basin wide analysis of megasequences indicates that tectonism was intermittent and regionally variable a maximum phase of subsidence and sediment accommodation is recorded in the middle unit of each megasequence and correlates with a notable abundance of fossil vertebrates suggesting a primary tectonic and basin response

new u pb zircon ages and the duration and division of devonian time newly determined u pb zircon ages of volcanic ashes closely tied to biostratigraphic zones are used to revise the devonian time scale they are 1 417 6 1 0 ma for an ash within the conodont zone of icriodus woschmidti i w hesperius early lochkovian 2 408 3 1 9 ma for an ash of early emsian age correlated with the conodont zones of po dehiscens lower po inversus 3 391 4 1 8 ma for an ash within the po c costatus zone and probably within the upper half of the zone eifelian and 4 381 1 1 3 ma for an ash within the range of the frasnian conodont palmatolepis punctata pa punctata zone to upper pa hassi zone u pb zircon ages for two rhyolites bracketing a palyniferous bed of the pusillites lepidophyta spore zone are dated at 363 8 2 2 ma and 363 4 1 8 ma respectively suggesting an age of363 ma for a level within the late famennian pa g expansa zone these data together with other published zircon ages suggest that the base and top of the devonian lie close to 418 ma and 362 ma respectively thus lengthening the period by20 over current estimates we suggest that the duration of the middle devonian eifelian and givetian is rather brief perhaps no longer than 11 5 myr 394 ma 382 5 ma and that the emsian and famennian are the longest stages in the period with estimated durations of15 5 myr and 14 5 myr respectively 1998 elsevier science b v all rights reserved

middle jurassic turtles from the sichuan basin china a review the turtle fauna of the middle jurassic xiashaximiao formation in the sichuan basin and the type series of chengyuchelys baenoides young chow 1953 are revised by the absence of a mesoplastron and other shell characters both the holotype and paratype of chengyuchelys baenoides belong to the family xinjiangchelyidae and come probably from the upper jurassic shangshaximiao formation the middle jurassic turtle assemblage of the sichuan basin is composed of two entities the bashuchelyidae fam nov bashuchelys gen nov chuannanchelys gen nov and protoxinjiangchelys gen nov on the one hand and sichuanchelys on the other hand with the former as the dominant group bashuchelyids and xinjiangchelyids are closely related to one another while sichuanchelys is more primitive and has no shared apomorphic features with bashuchelyids the whole assemblage appears to be endemic to the sichuan basin at genus level and distinct from the late jurassic turtle fauna of the same basin in its relict nature and absence of the polycryptodira

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

biostratigraphy of the vendian cambrian sukharikha river section northwestern siberian platform the sukharikha river section contains more than 800 m of fossiliferous vendian and lower cambrian carbonate rock deposited in ramp shelf and slope environments a diverse fauna of small shelly fossils calcibionts brachiopods trilobites and archaeocyaths has allowed us to develop a multi taxa biostratigraphic framework for this section a dearth of distinctive fossils low in the sukharikha formation prevents us from determining the position of the vendian cambrian boundary abundant small shelly fossils and archaeocyaths in the uppermost sukharikha formation and low in the krasnoporog formation provide ample biostratigraphic control near the base of the tommotian stage but the nemakit daldynian tommotian boundary as defined at ulakhan sulugur on the aldan river is temporally ambiguous for this reason there is no precise definition of this boundary in the sukharikha river section we have provisionally placed the base of the tommotian stage at the first occurrence of nochoroicyathus sunnaginicus

a revision of ordovician series and stages from the historical type area this paper is a revision of the standard chronostratigraphy of the ordovician of the historical type area in england and wales the revision is a response to the need for more precise definitions of series and stages especially for practical international correlation in some cases this has entailed moving horizons for series bases away from those in the classical sections the scheme will be used as the standard for a forthcoming revision of the correlation chart of the british ordovician system the ordovician is divided into five series tremadoc arenig llanvirn caradoc and ashgill the llanvirn is extended to include part of the classical llandeilo series which is included within it as a stage where stage subdivisions of standard series have not yet been defined as in the tremadoc they are proposed in this paper however bancroft s fine stadial divisions of the caradoc which have been criticized for their brevity and local utility are combined into four new stages which will have wider application the former caradoc subdivisions are retained as substages for the purposes of regional correlation

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

a review of lower and middle palaeozoic biostratigraphy in west peninsular malaysia and southern thailand in its context within the sibumasu terrane abstract fossils from the cambrian to devonian rocks of southern thailand the langkawi islands mainland kedah perlis north perak and central west peninsular malaysia are listed and reviewed and their stratigraphy and correlation reassessed the hitherto anomalous record of the trilobite dalmanitina from malaysia is reviewed and found to be of latest ordovician hirnantian age rather than lower silurian age as previously reported and is considered a probable synonym of the widespread mucronaspis mucronata a new stratigraphical nomenclature is erected for part of the langkawi mainland kedah and perlis area successions in which the term setul limestone which stretched from the ordovician to the devonian is abandoned and replaced by the middle ordovician kaki bukit limestone the late ordovician and early silurian tanjong dendang formation the silurian mempelam limestone and the early devonian timah tasoh formation all underlying the paraconformity with the late devonian langgun red beds there was a single depositional basin in the generally shallow water and cratonic areas of southern thailand langkawi and mainland kedah and perlis in contrast to the deeper water basin of north perak only silurian rocks are dated with certainty within another basin in central west malaysia near kuala lumpur which were also cratonic and shallow water although to the east in west pahang there are basal devonian deeper water sediments with graptolites the area is reviewed in its position within the sibumasu terrane which in the palaeozoic also included central and northern thailand burma myanmar and southwest china part of yunnan province

absolute ages aren t exactly the time scales of important events and processes in geology and archaeology are ascertained through measurements of radioisotopes the accuracy of the dating depends critically on how well known the radioactive decay constants are in their perspective renne karner and ludwig discuss the role that discrepancies in decay constants play in the accuracy of radioisotope dating as dating measurements become increasingly precise geochronologists will have to confront these kinds of systematic errors

middle jurassic turtles from southern thailand a new genus and species of primitive cryptodiran turtle siamochelys peninsularis n g n sp from the middle jurassic mab ching locality in the southern peninsula of thailand is described on the basis of complete shells they are characterized by a combination of primitive features the presence of a pair of mesoplastra meeting on the midline and a series of derived characters loose plastron carapace attachment short diamond shaped entoplastron dorsal thickening of the lateral edge of the second to seventh peripheral plates expanded seventh to eleventh peripheral plates extension of the anal scute to the hyo hypoplastral suture or onto the hypoplastron midline sulcus sinusoidal and thus closely resemble chengyuchelys from the middle jurassic of china and more particularly xinjiangchelys and its relatives from the middle and late jurassic of china and central asia this supports a middle jurassic age for the locality and suggests that the sibumasu shan thai block was in contact with the asian mainland by that time

late middle ordovician olistostrome formation and magmatism along the red indian line the laurentian arc gondwanan arc boundary at sops head newfoundland the sops head complex of badger bay central newfoundland includes olistostromal and tectonized melanges and marks the red indian line the boundary between the peri gondwanan exploits and peri laurentian notre dame subzones of the oceanic dunnage zone basalts in the olistostromal melange preserve peperitic contacts with mudstone and limestone within slumped sedimentary units demonstrating that magmatism was coeval with olistostrome formation conodonts from the limestones date these events as late darriwilian llandeilian middle ordovician in age the conodont fauna consists entirely of north atlantic faunal realm elements suggesting a peri gondwanan or mid iapetan provenance for limestone of the sops head complex basalt geochemistry suggests magmatism in a mature volcanic arc to back arc setting the sops head complex shows similarities in age provenance and stratigraphic setting to the dunnage melange suggesting that the two units are correlative

marine turtles from the late cretaceous of alberta canada previously reported and new specimens of marine turtles from the late campanian of alberta canada provide additional information on the diversity and distribution of chelonioid turtles at this time an articulated carapace from the bearpaw formation previously interpreted as lophochelys niobrarae is considered to be a juvenile of a specifically indeterminate chelonioid and is referred to lophochelys sp isolated neurals and a hyoplastron from nonmarine estuarine deposits in the uppermost beds of the dinosaur park formation are tentatively referred to lophochelys sp these specimens suggest that this chelonioid could enter freshwater environments a new chelonioid kimurachelys slobodae gen et sp nov is recognized on the basis of two mandibles and a maxilla from the uppermost beds of the dinosaur park formation of southeastern alberta a partial postcranial skeleton of an indeterminate chelonioid from the bearpaw formation provides additional evidence that chelonioids of this formation included taxa that were phylogenetically intermediate between chelonioids of the late santonian and members of the crown group

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

kalasinemys a new xinjiangchelyid turtle from the late jurassic of ne thailandh tong et al new xinjiangchelyid turtle from ne thailand a new xinjiangchelyid turtle kalasinemys prasarttongosothi n gen n sp is described on the basis of skull and shell material from the upper jurassic phu kradung formation at phu noi locality kalasin province in ne thailand this second xinjiangchelyid turtle from phu noi is distinct from phunoichelys thirakhupti by the smooth shell surface the presence of a cervical notch and vertebral 1 narrower than nuchal the skull presents an arterial system characteristic of the xinjiangchelyidae basal eucryptodira and its outline is similar to that of annemys spp known from the middle late jurassic of china and mongolia but distinct from the latter mainly by the wider triturating surface smaller foramen palatinum posterius and the shape of the prefrontal and frontal as well as that of the basisphenoid and basioccipital based on the turtle assemblages the correlation with mainland asia further supports a late jurassic age for the lower part of the phu kradung formation where phu noi site is located stratigraphically our study provides new insight on the evolution of the basal eucryptodiran turtles in asia

a theropod dinosaur feeding site from the upper jurassic of the junggar basin nw china abstract direct evidence for theropod feeding behaviour is rare in the fossil record and mainly limited to bite marks on bones here we describe a dinosaur assemblage from the lower part of the early late jurassic qigu formation at liuhuanggou gorge southern junggar basin nw china which has yielded fragmentary remains of a large sauropod as well as four teeth of large sized theropods and one tooth of a small sized theropod the sauropod bones show numerous bite marks that can be confidently linked to the large sized theropod probably a metriacanthosaurid the abundance of the theropod bite marks on a single skeleton indicates that the sauropod carcass was probably fed on extensively some bones are completely crushed and occur in patches of hundreds of tiny individual fragments indicating that they were trampled repeatedly by large dinosaurs both the feeding traces and the trampling suggests that the sauropod carcass was exposed for a substantial amount of time before it was finally buried within the deposits of a well drained floodplain the traces and the distinct preservation of the sauropod remains offer valuable insights into the feeding behaviour of large sized theropods within late jurassic continental ecosystems

new uppermost cambrian u pb date from avalonian wales and age of the cambrian ordovician boundary a crystal rich volcaniclastic sandstone in the lower peltura scarabaeoideszone at ogof ddu near criccieth north wales yields a u pb zircon age of 491 1 ma this late late cambrian date indicates a remarkably young age for the cambrian ordovician boundary whose age must be less than 491 ma hence the revised duration of the post placentian trilobite bearing cambrian indicates that local trilobite zonations allow a biostratigraphic resolution comparable to that provided by ordovician graptolites and mesozoic ammonites

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

a revision of sinaspideretes wimani young chow 1953 testudines cryptodira trionychoidae from the jurassic of the sichuan basin china sinaspideretes wimani young chow 1953 was based on a single shell from the jurassic red beds of the sichuan basin originally referred to trionychidae but later tentatively assigned to carettochelyidae it was long thought to be the oldest representative of those families the re examination of the carapace and further preparation of the plastron of the holotype of s wimani revealed a number of important characters which clearly exclude this taxon from both trionychidae and carettochelyidae but unite it with the primitive trionychoid yehguia tatsuensis ye 1963 s wimani is therefore considered as the basalmost member of trionychoidae our study adds to the evidence from the fossil record for the antiquity of trionychoidae thus is in agreement with the early split of trionychia trionychidae and carettochelyidae among the crown testudines suggested by the molecular phylogeny of turtles

a late cretaceous turonian coniacian high latitude turtle assemblage from the canadian arctic three turtles are present in a turonian coniacian age high latitude vertebrate assemblage from axel heiberg island borealochelys axelheibergensis gen et sp nov a generically indeterminate eucryptodire and a trionychid the assemblage differs from most late cretaceous turtle assemblages from north america in that members of the paracryptodira are absent the absence of this group is interpreted as a result of latitudinal differentiation of turtle assemblages in north america during the late cretaceous the level of diversity of turtles in the axel heiberg assemblage is comparable to that of mid latitude assemblages associated with a mean annual paleotemperature of 14 c adding to the evidence for high mean annual temperatures at high latitudes during turonian coniacian times

sunosuchus junggarensis sp nov archosauria crocodyliformes from the upper jurassic of xinjiang people s republic of china a new species of crocodyliformes sunosuchus junggarensis is established on the basis of six individuals from the upper jurassic of the junggar basin xinjiang northwest china it differs from other species of sunosuchus primarily in having a dorsoventrally depressed supraoccipital that in occipital view lacks a median crest a frontal that is ridged anteriorly a distinct depression distal to the foramen aereum on the dorsal surface of the quadrate and an elongate undivided maxillary depression cranial ontogenetic variation in s junggarensis is discussed sunosuchus is probably a goniopholidid crocodyliform it is distinguished from other genera of the goniopholididae by a narrow and elongate snout a small skull table a partially ridged frontal a pair of anteriorly located anterior palatal fenestrae a lateroventrally mediodorsally expanded retroarticular process some enlarged pits on the frontal and an elongate mandibular symphysis with the splenial forming a small part of it sunosuchus

full wavefield inversion of surface waves for mapping embedded low velocity zones in permafrost abstractsurface waves are advantageous for mapping seismic structures of permafrost in which irregular velocity gradients are common and thus the effectiveness of refraction methods are limited nevertheless the complex velocity structures that are common in permafrost environments often yield unusual dispersion spectra in which higher order and leaky modes are dominant such unusual dispersion spectra were prevalent in the multichannel surface wave data acquired from our permafrost study site at barrow alaska owing to the difficulties in picking and identifying dispersion curves from these dispersion spectra conventional surface wave inversion methods become problematic to apply to overcome these difficulties we adopted a full wavefield method to invert for velocity models that can best fit the dispersion spectra instead of the dispersion curves the inferred velocity models were consistent with collocated electric resistivity results and with subsequent confirmation cores which indicated the re

tournaisian age of granitoids from the odra fault zone southwestern poland equivalent of the mid german crystalline high the odra fault zone of southwestern poland is a nw trending horst marked by gravimetric and magnetic anomalies and composed of high to low grade metamorphic and igneous rocks which are only known from boreholes this zone embraces a concealed border between variscan internides and externides it also contains an array of several i type metaluminous to peraluminous high potassic granitoid bodies which intruded earlier metamorphosed rocks except for one case they remain unfoliated and undeformed and presumably play a role of stitching plutons at the suture between two obliquely colliding terranes u pb tims dating of single zircons from one foliated and one unfoliated granitoid samples yielded identical concordant ages of 344 1 ma tournaisian they resemble a pb pb age of 350 5 ma obtained for s type granitoids from the luckau area further west in germany which is generally regarded as an eastern segment of the mid german crystalline high carboniferous granitic intrusions in the high are generally younger 340 290 ma correlations of the the odra fault zone with the mid german crystalline high appear plausible but by no means certain and require further confirmation

transition zone reflections and permafrost analysis the usual study of seismic reflections is limited to those from sharply defined contrasts in acoustic impedance for reflections resulting from transition zones in which acoustic impedance is continuously variable such as the zones encountered in permafrost the frequency selective nature of attenuation and phase distortion leads to a number of characteristics which may be used in the sense of pattern recognition to identify such reflections an rms velocity analysis procedure can be used to estimate depths and velocity gradients associated with transition zones some simple approximations allow us to avoid solving a system of nonlinear equations in many cases of interest and the result is a practical technique which can be applied to many transition zone reflections at reasonable computational cost

the influence of clay sized particles on seismic velocity for canadian arctic permafrost seismic wave velocities have been measured on 37 unconsolidated permafrost samples as a function of temperature in the range 16 to 5 c the samples taken from a number of locations in the canadian arctic islands the beaufort sea and the mackenzie river valley were tighty sealed immediately upon recovery in several layers of polyethylene film and maintained in their frozen state during storage specimen preparation and until they were tested under controlled environmental conditions during testing the specimens were subjected to a constant hydrostatic confining stress of 0 35 mpa 50 psi under drained conditions at no stage was a deviatoric stress applied to the permafrost specimens the fraction of clay sized particles in the test specimens varied from almost zero to approximately 65 at temperatures below 2 c the compressional wave velocity was observed to be a strong function of the fraction of clay sized particles but only a weak function of porosity at temperatures above 0 c the comp

geology and paleobiology of islands in the ordovician iapetus ocean review and implications a history of islands in the iapetus ocean and their destruction is recorded by widespread occurrences of lower to upper ordovician volcanic and epiclastic rocks and some limestone through the axial parts of the appalachian caledonide orogen in north america and northwestern europe assemblages of arenigian and llanvirnian benthic shelly fossils chiefly brachiopods from these rocks constitute the celtic biogeographic province that is distinguished by its endemic genera and by some that are older than in other biogeographic provinces some that are younger than elsewhere and others that have not hitherto been found together evidence from these fossils and from the geology of the rocks pertaining to them suggests that north american terranes that included islands of arenigian llanvirnian age lay at middle to high latitudes both in mid ocean and within the armorican continental margin whereas coeval rocks in west central ireland and norway that have toquima table head shelly fossils were originally part of the laurentian continental margin eradication of the celtic assemblage and the reduction of ordovician faunal provinciality in the appalachian caledonide region coincide with llanvirnian obduction subduction of hundreds of kilometres of iapetus ocean crust late llanvirnian and younger ordovician rocks in the remnant basin including some of peri insular origin have brachiopods of scoto appalachian affinities no discrete islands of ashgillian age have been recognized although fossiliferous volcaniclastic and polymictic conglomerates indicate intermontane basins in some places shelly fossils in these rocks and those in the siltstones and limestones from the gaspe peninsula are like those of ashgillian age elsewhere