selachians from the niobrara formation of the upper cretaceous coniacian of carrot river saskatchewan canada acid etching of a shell bed zone has enabled us to reclaim numerous fish remains for the niobrara formation coniacian of east central saskatchewan including teeth of the following new taxa odon

geochemical characterization of selected western canada oils by c5 c8 compound specific isotope correlation csic abstract forty two oils condensates from the western canada sedimentary basin wcsb ranging in reservoir age from devonian to cretaceous are compared using the stable carbon isotopic ratio of individual hydrocarbons in the gasoline range fraction c 5 c 8 of these oils continuous flow isotope ratio mass spectrometry cf irms using a modified solid dilution purge and trap inletting system can provide reproducible isotopic ratios for the ca 26 dominant n iso and cyclo alkanes and aromatics in the gasoline range the resulting isotopic signatures or gasoline isotopograms for oils condensates provide a diagnostic geochemical technique for oil oil and oil source correlations in many instances the non straight chained hydrocarbons are more diagnostic than n alkanes hierarchical cluster analysis provides a non subjective approach to the treatment of individual isotopic information this study confirms that oils from similar or the same sources produce isotopic signatures that are highly correlated clear carbon isotopic relationships between individual hydrocarbon compounds in the oils suggest a steady state kinetic relationship for the generation of oil and gas as opposed to a thermodynamic equilibrium relationship this mechanism explains the consistent shift in isotopic ratios between similar compounds such as the methylalkanes and dimethylalkanes

recovery of source time function approximations by homomorphic deconvolution of broad band recorded teleseismic body waves abstract an improved method of interactive cepstral analysis and homomorphic deconvolution is employed to recover basic wavelets representing an approximation of source time functions from broad band records of teleseismic body waves radiated from nine events in the subducting lithosphere of the kurile arc the depths of the events ranged from 5 to 131 km five of them occurred above the slab of the subduction and four inside the slab the recovered wavelets of the deepest event correspond to an explosive implosive like source and those of three shallow events are similar to the theoretical shapes for simple kinematic dislocation models the recovered wavelets of two events inside the slab and some of the obtained impulse traces exhibit anomalies the explanation of which is at present beyond the abilities of the authors the direction of the continuation of the study is outlined

diagenetic and catagenetic products of isorenieratene molecular indicators for photic zone anoxia a wide range of novel diagenetic and catagenetic products of the diaromatic carotenoid isorenieratene a pigment of the photosynthetic green sulphur bacteria chlorobiaceae has been identified in a number of sedimentary rocks ranging from ordovician to miocene compound identification is based on nmr mass spectrometry the presence of atropisomers and stable carbon isotopes atropisomers contain an axially chiral centre which in combination with other chiral centres results in two or more diastereomers that can be separated on a normal gc column chlorobiaceae use the reverse tca cycle to fix carbon so that their biomass is enriched in 13c high 13c contents of isorenieratene derivatives therefore support their inferred origins isorenieratene derivatives include c 40 c 33 and c 32 diaryl isoprenoids and short chain aryl isoprenoids with additional aromatic and or s containing rings c 33 and c 32 compounds are diagenetic products of c 33 and c 32 carotenoids formed from isorenieratene during early diagenesis through expulsion of toluene and m xylene respectively cyclisation of the polyene acyclic isoprenoid chain can proceed via an intramolecular diels alder reaction followed by aromatisation of the newly formed ring sulphurisation is also an important process during early diagenesis competing with expulsion and cyclisation sulphur bound isorenieratane is released during progressive diagenesis due to cleavage of relatively weak ss and cs bonds cleavage of c c bonds during aromatisation of newly formed rings and during catagenesis yields short chain compounds the inherent presence of a conjugated double bond system in carotenoids implies that similar diagenetic and catagenetic reactions can occur with all carotenoids chlorobiaceae live at or below the oxic anoxic boundary layer and require both light and h 2s the presence of isorenieratene or its diagenetic and catagenetic products in ancient sedimentary rocks and crude oils is therefore an excellent indication for photic zone anoxia in the depositional environment diagenetic and catagenetic products of isorenieratene are expected to find applications in reconstruction of palaeoenvironments and in oil oil and oil source rock correlation studies their presence in several petroleum source rocks suggests that anoxia is an important environmental parameter for the preservation of organic matter

correlation of basinal carbonate cycles to nearshore parasequences in the late cretaceous greenhorn seaway western interior u s a upper cretaceous limestone shale couplets developed within the late transgressive stage of the greenhorn cyclothem may be correlated from carbonate dominated basinal sequences in central kansas and colorado westward to clastic cycles in southern utah six such basinal couplets have been traced to corresponding upward coarsening progradational cycles developed on the western margin of the western interior basin in the central basin in colorado and kansas these sedimentary cycles are represented by limestone shale and marlstone shale couplets 0 5 1 0 m in thickness more calcareous parts of these couplets may be correlated westward into condensed fossiliferous concretion and shell beds in proximal offshore lithofacies of arizona and utah these concretion and shell beds are physically traceable farther landward westward into bioturbated fossil rich transgressive lag deposits that bound 10 to 20 m thick coarsening upward progradational strand plain deposits parasequences in southwestern utah thus the progra dational phase of parasequence deposition correlates with accumulation of clay rich sediment in the central basin and the transgressive phase is characterized by reduced terrigenous input and deposition of carbonate rich sediment we consider milankovitch style orbital forcing of climate and tectonically induced fluctuations in rates of foredeep basin subsidence as possible forcing mechanisms for these basinwide events based on the widespread distribution of the limestone shale couplets as well as on estimated sedimentation rates and geochronology it has been widely speculated that these carbonate cycles reflect milankovitch cycles with periodicities on the order of 20 k y to 100 k y if so then stratigraphic data suggest that orbital forcing of climate affected eustasy and or sediment input and biogenic production in the western interior basin alternatively thrusting events in the sevier orogenic belt may have produced episodic changes in the rates of foredeep basin subsidence and consequent changes in base level which could have controlled the deposition of the greenhorn parasequences and carbonate cycles in either case correlation of these units demonstrates a consistent basinwide sedimentary response to high frequency base level or sediment input changes in the western interior epicontinental basin

ichthyornis aves from the early turonian late cretaceous of alberta an isolated left humerus from the cretaceous toothed bird ichthyornis is described the fossil comes from the vimy member of the kaskapau formation at watino alberta and is early turonian in age the watino specimen is the oldest well authenticated record of ichthyornis and the oldest cretaceous skeletal fossil of a bird from the western hemisphere the wide geographic distribution of ichthyornis within the western interior of north america is in keeping with nomadic habits as inferred from strongly flying modern marine birds

distribution and origin of ethyl branched alkanes in a cenomanian transgressive shale of the western interior seaway usa abstract monoethylalkanes mea c16 c22 with an even number of carbon atoms are relatively abundant in the saturated hydrocarbon fraction of the basal graneros shale cenomanian western interior seaway usa on the basis of isomer distribution and isotopic composition it is proposed that mea derive from eubacterial organisms possibly cyanobacteria living in fresh to brackish water environments

maturity assessment of oils from the sakhalin oil fields in russia phenanthrene content as a tool a correlation analysis of maturation parameters was carried out on 14 crude oil samples from nine oil fields on sakhalin island russia the oils were taken from reservoir rocks of miocene age at depths ranging from 73 to 2841 m on the basis of gc analysis of the alkane fraction n alkanes and the isoprenoid alkanes pristane and phytane as well as on the basis of the abundance of demethylated hopanes gc ms analysis m z 177 it is assumed that the oils are either biodegraded or are a mixture of biodegraded and nonbiodegraded oils therefore their maturation is assessed on the basis of the distribution and abundance of tricyclic aromatic hydrocarbons that are more resistant to biodegradation than alkane type biological markers the oils may be classified into three groups on the basis of the well established maturation parameter mpi 3 highly mature group i moderately mature group ii and immature group iii the correlation analysis shows that the percentage of phenanthrene p in the tricyclic aromatic fraction of the oils of the sakhalin oil fields can be used as a maturation parameter the highly mature oils group i were found to have a p value of more than 14 the moderately mature oils group ii have values of 7 14 and the immature oils group iii a value of less than 7 the very good correlation between mpi 3 and p also indicates that parallel to methylphenanthrene isomerization dealkylation also occurs in the reservoir rocks by correlation analysis it is shown that these reactions are to a great extent determined by the depth of the reservoir rocks

back calculation of the in den arelen avalanche with ramms interpretation of model results two and three dimensional avalanche dynamics models are being increasingly used in hazard mitigation studies these models can provide improved and more accurate results for hazard mapping than the simple one dimensional models presently used in practice however two and three dimensional models generate an extensive amount of output data making the interpretation of simulation results more difficult to perform a simulation in three dimensional terrain numerical models require a digital elevation model specification of avalanche release areas spatial extent and volume selection of solution methods finding an adequate calculation resolution and finally the choice of friction parameters in this paper the importance and difficulty of correctly setting up and analysing the results of a numerical avalanche dynamics simulation is discussed we apply the two dimensional simulation program ramms to the 1968 extreme avalanche event in den arelen w e show the effect of model input variations on simulation results and the dangers and complexities in their interpretation

vertebrates from the middle late cenomanian la cabana formation asturias northern spain palaeoenvironmental and palaeobiogeographic implications article i nfo the asturian la cabana formation middle late cenomanian in age has yielded a rich and diverse assemblage of vertebrate microremains the fauna consists of both marine and continental forms including chimaeroids various selachians and actinopterygians chelonians crocodilians plesiosaurs pterosaurs sauropod dinosaurs and marine squamates this mixed assemblage of autochthonous coastal and allochthonous continental elements comes mainly from a transgressive lag occurring near the base of the formation it also contains some remains which are probably reworked from older middle cenomanian deposits palaeontological taphonomic and sedimentologic data indicate a shallow platform and marine lagoon with addition of some continental elements a comparison with the late cenomanian vertebrate assemblage of charentes southwestern france shows numerous similarities between both areas some taxa only known from asturias and charentes e g the aigialosaur carentonosaurus suggest that the opening bay of biscay may have constituted a palaeobiogeographic area characterized by endemism during the mid cretaceous

a new paraclupeid fish clupeomorpha ellimmichthyiformes from a muddy marine pro delta environment middle cenomanian dunvegan formation alberta canada a black marine mudstone in allomember a of the middle cenomanian dunvegan formation alberta yielded a well preserved deep bodied fish skeleton attributable to a new genus and species tycheroichthys dunveganensis in the paraclupeidae clupeomorpha ellimmichthyiformes this new taxon appears most closely related to members of the subfamily paraclupeinae which includes largely freshwater and estuarine or marginal marine species known from south and central america and china the dunvegan formation represents a large delta complex deposited in the western interior seaway at about 65 n where mean sea water temperature may have been about 10 c the specimen was found about 60 km from the contemporaneous shoreline and in life apparently inhabited a shallow muddy pro delta environment characterized by high turbidity and variable salinity the fish may have died when it was engulfed by brackish floodwater that also introduced suspended mud that rapidly buried the body preventing physical disarticula

middle turonian dinosaur paleoenvironments in the upper cretaceous kaskapau formation northeast british columbia the kaskapau formation is a mudstone dominated wedge up to 950 m thick that spans late cenomanian to middle turonian time the formation has a prominent wedge geometry and was deposited in the foredeep of the western canada foreland basin in outcrop in northeast british columbia nearshore sandstones are locally well developed and include rare wedges of nonmarine strata on quality creek near tumbler ridge 11 m of nonmarine strata contain abundant dinosaur tracks and the first in situ dinosaur bone reported from british columbia this site at a paleolatitude of about 67 n preserves a rare glimpse of turonian terrestrial environments during global eustatic highstand three main dinosaur habitats are recognized strandplain and beach ridge freshwater lake and brackish lagoon back beach sandstone has a relief of about 2 5 m interpreted as beach ridges sandy coals containing abundant dinosaur tracks represent inter ridge slough deposits overlying lake deposits comprising laminated muds with freshwa

identification of aryl isoprenoids in source rocks and crude oils biological markers for the green sulphur bacteria abstract a series of c13 to c31 aryl isoprenoids 1 alkyl 2 3 6 trimethylbenzenes have been identified in reef hosted oils and their source rocks from the middle and upper silurian of the michigan basin and middle devonian of the alberta basin canada their structure has been confirmed by unambiguous synthesis of the c14 member of the series their structure and isotopic composition indicate that they are derived from isorenieratene from the chlorobiaceae family of sulphur bacteria these results are consistent with geological and geochemical studies that show that the source rocks were deposited under metahaline to hypersaline sulphate and sulphide rich water columns the distribution of other biomarkers in these oils and source rocks indicates that a diverse biota contributed organic matter to the source environment in conjunction with the aryl isoprenoids they show that there is a remarkable similarity in composition between the two sets of oils and source rocks despite their great temporal and geographic separation this reflects the similarity of their environments and emphasizes the importance of sedimentary facies in controlling the composition of organic matter in source rocks and their derived oils

snow avalanche penetration into mature forest from timber harvested terrain clear cut logging in british columbia canada is creating new avalanche start zones from which snow avalanches sufficient in size to penetrate and destroy mature forest cover can initiate in addition to creating new start zones the presence of these logging cut blocks can augment the destructive potential of previously existing avalanche paths forest penetrating avalanches can pose a significant risk to down slope structures and resources this study is the first to develop and utilize a database containing information on penetration distances and lateral spread from avalanches that have penetrated forest cover the study area for this research spans the southern coast and columbia mountains of british columbia canada analysis focuses on terrain characteristics related to forest penetration and the resultant destruction of mature standing forest physical terrain and vegetation characteristics in the avalanche starting zone track and runout zone of 45 forest penetrating avalanches are described m

study of a large scale dry slab avalanche and the extent of damage to a cedar forest in the makunosawa valley myoko japan accurate measurements of snow avalanche flows in forests are rare to understand how forests can stop avalanches we study a mixed flowing avalanche that stopped in a cedar cryptomeria japonica forest in japan the large scale dry slab avalanche occurred in the makunosawa valley in myoko on 17 february 2008 and damaged many trees the site contains a geophone and other devices to detect avalanche activity a nearby meteorological station provides weather information post event observations were made of the scale of the avalanche and tree damage these showed that the avalanche released from the east southeast facing slope at 1700 m a s l snow debris reached 770 m a s l the horizontal runout distance was 3000 m the area of the runout zone was 10 ha and the snow water equivalent of debris was 400 1500 mm the mass of the avalanche was roughly estimated at 5 10 10 7 kg 1 2 10 5 m 3 we used snowpack simulation models to estimate the height of the fracture zone the simulations revealed that a faceted snow layer formed at 2 m and the stability index was 0 5 poor at the time of the avalanche release due to heavy snowfall we estimated the avalanche velocity from the bending stress of the broken cedar trees in order to verify the effect of forests in reducing avalanche velocity the avalanche was estimated to flow into the forest at a velocity of 26 31 m s 1 with a 17 m high powder snow layer and a dense flow layer 2 m in height it appears to have slowed down and stopped at 130 m after penetrating the upper edge of the forest

paleobiogeography of the cretaceous western interior seaway of north america the vertebrate evidence abstract distribution patterns of marine vertebrates of the cretaceous western interior seaway of north america are analysed in a biogeographical context the analysis is based on fossil vertebrate assemblages from the following lower campanian localities 1 anderson river fauna n w t 2 pembina fauna southern manitoba 3 sharon springs fauna south dakota wyoming 4 niobrara fauna kansas 5 mooreville fauna alabama due to the cosmopolitan nature of many marine vertebrates relative abundance is used in preference to presence absence data in identifying faunal distribution patterns the analysis demonstrates the presence of two faunal subprovinces in the seaway the northern interior subprovince is characterized by a low diversity in all groups and is dominated by plesiosaurs hesperornithiforms and the mosasaur platecarpus the southern interior subprovince is characterized by a high diversity in all groups and is dominated by sharks turtles and the mosasaur clidastes these biogeographical subdivisions support the hypothesis of warm temperature and cool temperate zones in the seaway that have been proposed on the basis of invertebrate faunas

parallel adaptive numerical simulation of dry avalanches over natural terrain high fidelity computational simulation can be an invaluable tool in planning strategies for hazard risk mitigation the accuracy and reliability of the predictions are crucial elements of these tools being successful we present here a new simulation tool for dry granular avalanches using several new techniques to create a highly accurate tool with a combination of good models and numerical methodologies highlights of our methodology are the use of a depth averaged model of the conservation laws and an adaptive grid godunov solver to solve the resulting equations the software is designed to run on distributed memory supercomputers and make use of digital elevation data dynamically i e refine the grid and input data to finer resolutions to better capture flow features as the flow evolves our simulations are validated using quantitative and qualitative comparisons to tabletop experiments and data from field observations our software is freely available and can be used on a range of hardware from inexpensive desktop computers to the largest supercomputers

a middle cenomanian euselachian assemblage from the dunvegan formation of northwestern alberta a euselachian assemblage was recovered from the middle cenomanian dunvegan formation situated in northwestern alberta this assemblage is the most northern described within the western interior seaway and provides an important insight into the euselachian faunal diversity of this little known region of the seaway despite its high paleolatitude the assemblage contains a number of elasmobranch taxa including hybodus squalicorax archaeolamna cretodus dallasiella and cretoxyrhina the dunvegan assemblage also contains the first known reports from canada of the odontaspid shark johnlongia parvidens the cretoxyrhinid shark protolamna carteri and the ray pseudohypolophus mcnultyi this assemblage extends the northern geographical range of all taxa preliminary comparisons with other middle cenomanian western interior seaway assemblages show that the core composition of the dunvegan assemblage is remarkably similar to that of other time equivalent assemblages however conspicuously absent are species t

thrust loads and foreland basin evolution cretaceous western united states two dimensional modeling of loading during the formation of the idaho wyoming thrust belt shows that regional isostatic compensation by flexure of an elastic lithosphere is sufficient to control the formation of a foreland basin the flexural rigidity of the lithosphere is inferred to have been approximately 1023 nm 1030 dyne cm on the basis of palinspastic comparison of predicted downwarping due to the thrust plate loads to the shape of the sedimentary wedge on the west side of the cretaceous western interior seaway erosion of part of the uplifted thrust plates redistributed the load depositing it farther to the east thereby causing subsidence over a much wider area than could have been accomplished only by the loading by thrust plates paleotopography after major cretaceous thrust events was calculated the resulting mountainous terrain gentle alluvial plain and flat sea floor correspond well with the topography of the modern foreland thrust belt and basin system in the andes of south america and to paleogeographic reconstructions in the western united states thrust belt topography is controlled by the subsurface geometry of the thrust faults particularly the positions of ramp zones and by isostatic subsidence

late cretaceous campanian actinopterygian fishes from the kristianstad basin of southern sweden although a diverse range of aquatic vertebrates are documented from the upper cretaceous mid campanian marine strata of the kristianstad basin in southern sweden only chondrichthyans and marine amniotes have been described in detail to date in contrast coeval actinopterygians are virtually unreported yet their remains are extremely abundant at most sampled localities a comprehensive assessment of these fossils has identified the first late cretaceous actinopterygian fauna from the fennoscandian shield incorporating indeterminate lepisosteids the durophagous pycnodontid anomoeodus subclavatus the predatory pachycormid protosphyraena sp a large ichthyodectid pachyrhizodontids resembling pachyrhizodus the enchodontid enchodus cf gladiolus and indeterminate small teleosts these taxa are diagnosed mainly from isolated teeth and scales implying substantial taphonomic loss prior to burial moreover the prolific recovery of actinopterygian skeletal remnants in recent excavations suggests that historical collecting biases rather than ecological paucity have contributed to their under representation in the swedish cretaceous record palaeobiogeographically the kristianstad basin actinopterygians show compositional resemblance to assemblages from the northern european platform and the western interior seaway of north america advocating distributional communication across the boreal proto atlantic ocean

chlorobiaceae in palaeozoic seas revealed by biological markers isotopes and geology biomarker hydrocarbons in oils and sediments have considerable potential for assessing the nature of biological processes in the past but only a few can be uniquely related to particular organisms reef hosted oils in the silurian of the michigan basin canada and the devonian of western canada have high abundances of 1 alkyl 2 3 6 trimethylbenzenes their precise structures suggest that they are diagenetic products of aromatic carotenoids of the green sulphur bacteria individual components are enriched in 13c by 7 8 relative to the saturated hydrocarbons of the same oil an isotopic anomaly of this magnitude and direction correlates with a component of photosynthetic carbon assimilation by the reductive tricarboxylic acid cycle these results together with data on palaeoenvironments provide compelling evidence for the existence in ancient restricted seas of microbial communities containing chlorobiaceae organisms with distinctive biochemistry which leave morphologically identifiable remains

fossil marine actinopterygian fishes from the kaskapau formation upper cretaceous turonian near watino alberta turonian fossil marine fishes occur at several localities near watino alberta in sandstones and in shale concretions of the vimy member kaskapau formation the actinopterygian fossils in the san

observations and modeling of the braking effect of forests on small and medium avalanches a long standing problem in avalanche science is to understand how forests stop avalanches in this paper we quantify the effect of forests on small and medium avalanches crucial for road and ski run safety we performed field studies on seven avalanches where trees affected the runout we gathered information concerning the release zone location and dimension deposition patterns and heights runout distance and forest structure in these studies the trees were not destroyed but acted as rigid obstacles wedge like depositions formed behind 1 individual tree stems 2 dense tree groups and 3 young trees with low lying branches using the observations as a guide we developed a one parameter function to extract momentum corresponding to the stopped mass from the avalanche the function was implemented in a depth averaged avalanche dynamics model and used to predict the observed runout distances and mean deposition heights for the seven case studies the approach differs from existing forest interaction models which modify avalanche friction to account for tree breakage and debris entrainment our results underscore the importance of forests in mitigating the danger from small to medium avalanches

correlation of physical surfaces bentonites and biozones in the cretaceous colorado group from the alberta foothills to southwest saskatchewan and a revision of the belle fourche second white specks formational boundary new allostratigraphic correlations in west central alberta show that flooding surfaces in the sunkay and basal vimy members of the blackstone formation can be traced eastward from burnt timber creek for 500 km to western saskatchewan and for 350 km northward into the dunvegan and kaskapau formations at burnt timber creek a miliammina manitobensis microfauna in the lowest 1 m of the sunkay member indicates equivalence to the westgate formation and an overlying 70 cm conglomerate is correlative with the fish scales formation overlying mudstones contain foraminifera of the verneuilinoides perplexus zone indicative of the middle cenomanian belle fourche formation the base of the second white specks formation as currently defined in core in eastern alberta equates in outcrop with the lower part of the sunkay rather than the base of the vimy member as previously thought the base of the second white specks formation should be placed about 35 m higher in the stratotype core a bentonite located 9 3 m

mid cenomanian vertebrate faunas of the western interior seaway of north america and their evolutionary paleobiogeographical and paleoecological implications abstract the western interior seaway wis was an epicontinental sea that extended north south through the middle of north america during the last half of the cretaceous linking the tethys sea to the south with the boreal paleo arctic ocean to the north aptian maastrichtian sedimentary deposits from the seaway crop out in the western interior basin of canada and the united states vertebrate remains are commonly well preserved and in certain stratigraphic units abundant the classic vertebrate fauna of the wis from the upper cretaceous niobrara chalk has been studied for 150 years but relatively little has been known of the seaway s earlier faunas until recent years studies of mid cenomanian vertebrate faunas particularly from lag deposits bonebeds and calcarenites in canada and the united states have significantly altered the previous picture of the overall biodiversity and biogeography of the wis during the mid cretaceous these mid cenomanian faunas include diverse fish assemblages of chondrichthyans cartilaginous fishes and osteichthyans bony fishes as well as various forms of tetrapods including marine turtles plesiosaurs and hesperornithiform and ichthyornithiform birds our compilation of faunas indicates that at least 70 vertebrate taxa are recorded from five mid cenomanian wis localities situated in alberta saskatchewan the black hills region of south dakota and wyoming kansas and colorado the faunas include 41 chondrichthyans 21 osteichthyans 10 non avian tetrapods and five avian taxa our study combined with previous faunal studies suggests that the combination of the following eight chondrichthyan species characterizes mid cenomanian time which has been referred to as the woodbinian age in the marine realm of north america ptychodus decurrens p occidentalis squalicorax curvatus cretodus semiplicatus carcharias amonensis c saskatchewanensis eostriatolamia tenuiplicatus and cretomanta canadensis this is the geologic time when non ptychodontid hybodonts became rare faunal components in most areas and when a number of other fish lineages particularly teleosts emerged and diversified many of these persisted into the early campanian or the niobrara age that followed the woodbinian therefore mid cenomanian time in the wis can also be characterized by the genesis of the niobraran fauna a significant radiation and diversification of fish taxa the five mid cenomanian wis localities highlighted in this study are separated by as much as 18 latitude a north south distance of more than 2300 km these faunas demonstrate some clinal trends such as more diverse faunas of benthic chondrichthyans mixed with dolichosaurid lizards to the south and a more diverse fauna of birds to the north however the faunas overall show strong taxonomic homogeneity particularly among many chondrichthyans that were cosmopolitan indicating that passage throughout the seaway as well as to both the boreal and tethys oceans was utilized these faunas also demonstrate high osteichthyan diversity in the northern waters of the wis which were once thought to have supported only a depauperate cold adapted fauna because of the surprisingly great diversity in vertebrate taxa ecosystem structure and dynamics of the wis during the mid cenomanian were unquestionably complex

late cretaceous cenomanian to campanian paleoenvironmental history of the eastern canadian margin of the western interior seaway bonebeds and anoxic events abstract upper cretaceous strata in the pasquia hills of the northern manitoba escarpment eastern saskatchewan canada provide a detailed paleoenvironmental and sea level record of the eastern margin of the western interior seaway sediments deposited during the cenomanian turonian greenhorn marine cycle are dominantly black mudstones deposited in a stratified water column with bottom water anoxia recurrently reaching into the photic zone a middle cenomanian sea level lowstand event followed by transgression left a series of bonebeds within the belle fourche member of the ashville formation indicating a sedimentary environment starved of coarse siliciclastics maximum sea level resulted in the formation of limestone beds within the favel formation further favoured by reduced terrigenous sediment input compared to the western margin limestone sedimentation was followed by a phase of increased freshwater input under lower sea level conditions and reducing zoo and phytoplankton diversities during final greenhorn regression eastern saskatchewan probably turned into a restricted basin severely limiting marine circulation poor or absent benthic foraminiferal assemblages and biomarker analysis suggest prevailing watermass stratification throughout the cenomanian turonian transgressive regressive cycle this was caused either by a freshwater lid stratification of boreal and tethyan derived watermasses or both to various intensities affected by changing sea level basin oxygenation during niobrara time varies between localities along the eastern margin as documented by presence absence of benthic and planktic foraminifera

can one determine seismic focal parameters from the far field radiation summary a number of postulates concerning the nature of faulting have been used in the construction of kinematical models which give the source parameters of seismic moment fault length and stress drop from the spectral properties of d c level and knee frequency several one dimensional models of faulting calculated as well posed boundary value problems are obtained which give both the source parameters and the far field radiation providing a test for these empirical relations the results for these models show that the high frequency content of the seismogram is usually associated not with the onset of fracture but with the onset of healing that is when the cessation of relative motion on the fault begins in some cases the high frequency part of the seismogram is also associated with the termination of rupture for different distributions of tectonic stress dynamical friction and cohesion healing can take place sonically supersonically or instantaneously over the entire fault the final state of stress may be less than or greater than the dynamical friction for four selected models of one dimensional faulting the calculation of fault parameters from the theoretical seismograms give internally consistent estimates of seismic moment unfortunately the theory shows that the estimates of fault length and stress drop made from the empirical formulas may be completely without value without additional information not usually derived from the radiation spectrum

a rupture model for the 1999 chi chi earthquake from inversion of teleseismic data using the hybrid homomorphic deconvolution method this study investigates the kinematics of the rupture process of the ml 7 3 chi chi taiwan earthquake on september 21 1999 by applying the proposed hybrid homomorphic deconvolution method to deconvolve teleseismic broadband p wave displacement recordings of the earthquake this study derives the apparent source time functions astfs at ten stations located around the epicenter to further characterize the fault the kinematic history of the rupture was inverted from astfs using a genetic algorithm coupled with nonlinear iterative technique the calculated asfts reveal that the total rupture event lasted for approximately 27 s static slip distribution images indicate that most slip occurred at shallower portions of the fault plane especially 20 55 km north of the epicenter the maximum slip reached 20 m at 45 km north of the epicenter and the average slip throughout the observed rupture area was approximately 2 m large asperities on the fault appeared at 25 35 km and 40 50 km north of the hypocenter and coincided with relatively high rupture velocity this suggests that the earthquake s energy may have been released quickly the rupture velocity decreased upon encountering an asperity and increased again after passing the asperity this implies that the rupture required more time to overcome the resistances of the asperities the maximum rupture velocity was 3 8 km s while the average rupture velocity was approximately 2 2 km s the rise time distribution suggests that larger slip amplitudes generally correspond to shorter rise times on the subfaults

an organic geochemical study of cenomanian turonian sediments from the western interior seaway canada abstract bulk geochemical and biomarker data were collected for three cenomanian turonian late cretaceous sections in the western canada sedimentary basin western interior seaway canada rock eval and biomarker analyses indicate an east west thermal maturity trend due to progressive deeper burial associated with the tectonic flexure of the foreland basin the source of extractable organic matter is dominantly marine with a minor terrestrial contribution a pseudohomologous family of 2 2 dimethylalkanes 2 2 dmas in the c 16 c 28 range with an even number of carbon atoms exclusively was tentatively identified from mass spectral data in samples from the pasquia hills region easternmost section the specific origin of 2 2 dimethylalkanes remains unclear the presence of isorenieratene derivatives indicates that the northern part of the western interior seaway experienced photic zone euxinic events throughout the transgressive highstand and regressive phases of the greenhorn cycle the differential occurrence of isorenieratane between the canadian sections and the united states transect at maximum sea level high stand indicates that the water column of the northern part of the wis was less oxygenated whereas the water column in the southern wis was more dynamic and well mixed

observations and numerical simulations of the braking effect of forests on large scale avalanches although the disaster reduction effects of forest braking have long been known empirically they have not been known in detail down to recent in this study we ascertained forest braking effect by numerical simulations using the avalanche dynamics program titan2d to model large scale avalanches one of these avalanches occurred in the makunosawa valley myoko and damaged a cedar forest the others occurred on mt iwate and damaged a subalpine forest all avalanches damaged many trees and terminated within the forests in our simulations the resistance of the forests to avalanches is simulated using a larger bed friction angle fitting the observations from the makunosawa avalanche by trial and error a bed friction angle of 13 14 in the non forested area and of 25 in the forested area is obtained we conducted simulations of the mt iwate avalanches using the same method as for the makunosawa valley avalanche and obtained good agreement between observations and simulations simulations reveal that without the forest the avalanche would have traveled at least 200 m farther than the forest s actual end in the makunosawa valley and at least 200 m and possibly up to 600 m farther on mt iwate this study therefore clearly shows that forests provide a braking effect for avalanches