modern sedimentary processes in the wilmington canyon area u s east coast abstract sedimentary processes active in the wilmington canyon area during the past century are documented from geochronologic sedimentologic and radiographic analysis of sediment cores collected using primarily d s r v alvin site selection for the alvin dives and for collection of box and kasten cores was achieved using sea marc and seabeam data allowing accurate sampling of numerous subenvironments from this extensively dissected area of the continental margin 210 pb sediment accumulation rates from intercanyon areas are highest on the upper slope 1 7 mm yr 140 mg cm 2 yr and decrease with water depth to about 0 4 mm yr 36 mg cm 2 yr on the upper rise within submarine canyons accumulation rates vary dramatically from a maximum of 6 mm yr 500 mg cm 2 yr to less than 0 3 mm yr 22 mg cm 2 yr higher accumulation rates in canyons occur as a result of additional supply of older sediment probably from bioerosion of the canyon walls this is supported by observations from d s r v alvin reduced 210 pb activities and indurated mud clasts observed in several canyon cores extremely low accumulation rates in wilmington and south wilmington canyons are probably the result of strong episodic boundary currents non steady state 210 pb profiles and sedimentologic data indicate small scale mass wasting in south heyes canyon and on the lower slope and rise just north of wilmington canyon

first evidence of juvenile ceratopsians reptilia ornithischia from the frenchman formation late maastrichtian of saskatchewan the first occurrence from the frenchman formation late maastrichtian of juvenile ceratopsians chasmosaurinae is reported here based on two postorbital horn cores the sutures confirm that the frontal attaches along the medial side of the postorbital much like that in centrosaurinae and cannot be used as a tool for distinguishing the two ceratopsid subfamilies

cadalenes and norcadalenes in organic rich shales of the permian irati formation parana basin brazil tracers for terrestrial input or also indicators of temperature controlled organic inorganic interactions abstract cadalene isocadalene and a series of norcadalenes were identified in black shales of the permian irati formation in the northeastern and central eastern parana basin brazil the origin of their isomers with an isopropyl substituent is potentially related to higher plants and likely reflects the spreading of pteridophytes and gymnosperms after the glaciation of southern gondwana a general increase in the relative abundance of isocadalene 1 6 dimethyl 3 isopropylnaphthalene the isomer co occurs in with increasing thermal maturity at the base of the amaral machado quarry northeastern basin and refers to the acid catalyzed rearrangement of cadalene 1 6 dimethyl 4 isopropylnaphthalene the isomer due to the presence of montmorillonite via an organic inorganic interaction this localized and incipient maturation can be related to diabase sills of the serra geral formation similar maturation due to heating also affected the distribution of the norcadalenes by thermally stabilizing their isomers with an isopropyl substituent in addition to the formation of related compounds with an ethyl substituent based on this a norcadalene ratio is proposed which is the sum of the 1 6 dimethyl 4 ethylnaphthalene and 1 6 dimethyl 3 ethylnaphthalene over the sum of the 1 isopropyl 4 methylnaphthalene and 1 isopropyl 7 methylnaphthalene the results of this ratio and the established cadalene ratio resemble each other whereas samples from the sao mateus do sul quarry central eastern basin were not affected by thermal maturation and are characterized by a uniform distribution of the cadalenes and norcadalenes

morphology and filling of incised submarine valleys on the continental shelf near the mouth of the fly river gulf of papua 1 much historical perspective about terrestrial and marine processes can be obtained from examination of fluvial valleys formed during lower sea level on surfaces that are now continental shelves the continental shelf near the mouth of the fly river gulf of papua has three incised valleys which were not extensively modified or filled during the holocene transgression multibeam mapping of the valleys documents their morphology seismic profiling reveals stratigraphy of sediment fill and coring within and near the valleys suggests mechanisms of filling kiwai valley is deep 20 50 m relief narrow 1 km wide steep sided and meandering due to river flows that caused its excavation through competent sedimentary deposits purutu valley is shallow 10 20 m relief and broad 2 km wide umuda valley is widest 14 km and has multiple channels with variable incision depths suggesting more extensive fluvial activity than the other two valleys valley filling has occurred in several ways reflecting valley morphology and location relative to the present river mouth kiwai and umuda valleys reveal three stages of infill 1 hemipelagic sedimentation at distal sites 2 gravity driven flows spreading down the valley and 3 subsequent clinoform progradation that completely fills the valley purutu valley fill is dominated by clinoform progradation clinoform progradation in umuda valley is driven by intense sediment reworking on the surrounding topset regions and its large width allows progradation from the sides as well as down its axis most shelf valleys around the world were filled long ago and available techniques have severe limitations for documenting the details of morphology and the mechanisms of filling the shelf valleys described in this paper provide a unique perspective to terrestrial and marine processes before during and after the holocene transgression

benthic fluxes and porewater concentration profiles of dissolved organic carbon in sediments from the north carolina continental slope abstract numerous studies of marine environments show that dissolved organic carbon doc concentrations in sediments are typically tenfold higher than in the overlying water large concentration gradients near the sediment water interface suggest that there may be a significant flux of organic carbon from sediments to the water column furthermore accumulation of doc in the porewater may influence the burial and preservation of organic matter by promoting geopolymerization and or adsorption reactions we measured doc concentration profiles for porewater collected by centrifugation and sipping and benthic fluxes with in situ and shipboard chambers at two sites on the north carolina continental slope to better understand the controls on porewater doc concentrations and quantify sediment water exchange rates we also measured a suite of sediment properties e g sediment accumulation and bioturbation rates organic carbon content and mineral surface area that allow us to examine the relationship between porewater doc concentrations and organic carbon preservation sediment depth distributions of doc from a downslope transect 300 1000 m water depth follow a trend consistent with other porewater constituents co2 and so42 and a tracer of modern fine grained sediment fallout pu suggesting that doc levels are regulated by organic matter remineralization however remineralization rates appear to be relatively uniform across the sediment transect a simple diagenetic model illustrates that variations in doc profiles at this site may be due to differences in the depth of the active remineralization zone which in turn is largely controlled by the intensity of bioturbation comparison of porewater doc concentrations organic carbon burial efficiency and organic matter sorption suggest that doc levels are not a major factor in promoting organic matter preservation or loading on grain surfaces the doc benthic fluxes are difficult to detect but suggest that only 2 of the dissolved organic carbon escapes remineralization in the sediments by transport across the sediment water interface

relative paleointensity rpi in the latest pleistocene 10 45 ka and implications for deglacial atmospheric radiocarbon abstract we report magnetic properties and relative paleointensity rpi proxies from a suite of 10 conventional piston cores and kasten cores from the sw iberian margin collected during cruise jc089 of the rss james cook in august 2013 mean sedimentation rates are in the 10 20 cm kyr range age models were acquired by correlation of ca ti and zr sr xrf core scanning data to l reflectance from the cariaco basin that is in turn tied to the greenland ice core chronology the natural remanent magnetization nrm is represented by a single magnetization component carried by a low coercivity mineral magnetite although reflectance and bulk magnetic properties indicate the presence of a high coercivity hematitic magnetic phase possibly from eolian dust the presence of fine grained hematite means that the sediments are not ideal for rpi studies however the detrital hematite does not appear to contribute to the nrm or anhysteretic remanent magnetization arm in order to test the usefulness of the rpi data we construct a stack of 12 rpi records from the sw iberian margin for the 0 45 ka interval and compare it with a stack of 12 globally distributed marine and lake records chosen on the basis of mean sedimentation rates 15 cm kyr and superior age models the two stacks are similar but different from published rpi stacks particularly for the 10 30 ka interval and imply a virtual axial dipole moment vadm high at 15 18 ka followed by a drop in field strength from 15 to 13 ka a revised vadm estimate calculated from greenland 10be ice core flux using a contemporary age model is remarkably consistent with the new overall rpi stack based on iberian margin and global rpi records the elevated atmospheric 14c levels of the last ice age cannot however be fully explained by this rpi stack although relative changes such as the long term drop in atmospheric 14c from 30 to 15 ka are reproduced supporting the hypothesis of a combined influence of production rate and ocean ventilation on 14c during the last ice age

phanerozoic low temperature evolution of the uruguayan shield along the south american passive margin the crystalline basement of uruguay was assembled during the brasiliano orogeny in the neoproterozoic era and was later affected by discrete tectonic activity a new multi method low temperature dataset including u th he ages from both zircon and apatite t t modelling and k ar dating of fine sericite fractions and fault gouge reveal a detailed post orogenic geological history spanning the phanerozoic eon the juxtaposition of the terranes that compose the area was achieved in the ediacaran period and post collision was marked by intense exhumation in which the crystalline basement reached near surface conditions by the early to mid palaeozoic regional subsidence promoted sedimentation in the parana basin until the permian covering and reheating much of the basement that is at present exposed afterwards deposition and volcanism were mostly confined to its current limits regional exhumation of the shield during the permo triassic exposed much of the northern portion of the basement and the south was further affected by the opening of the south atlantic ocean during the mesozoic little exhumation affected the uruguayan shield during the cenozoic as reflected in its modest topography the reactivation of inherited neoproterozoic structures influenced the development of mesozoic basins and the present day landscape supplementary material supplementary data sample locations u th he data and k ar data are available at https doi org 10 6084 m9 figshare c 3702043

the kerogen type depositional environment and maturity of the irati shale upper permian of parana basin southern brazil abstract two samples from the upper and lower horizons of the irati oil shale of the parana basin brazil were sampled in a single borehole and analysed using organic petrography and geochemistry the results are interpreted in terms of the kerogen type maturity and depositional environment of the two horizons organic petrography shows the oil shales to be composed of a mineral groundmass mainly clay minerals carbonate and pyrite associated and sometimes impregnated with fluorescing organic material and disseminated phytoclasts humic material is fairly rare and mostly present as very small particles the liptinitic particles are mostly alginite a and b sporinite and more rarely resinite reflectance measurements upper seam 0 34 r0 lower seam 0 40 r0 indicate an equivalent rank of lignite sub bituminous coal astm i e immature with respect to oil and gas generation different organic geochemical methods rock eval pyrolysis solvent extraction gc and gc ms demonstrate both samples to be immature rich oil shales 100 114 kg ton containing type i kerogen of a dominantly bacterially degraded algal origin deposited in a lacustrine environment the presence of botryococcus suggests deposition under fresh brackish water conditions a tentative interpretation of the extract and vitrinite reflectance data suggests a maximum paleo burial of between 1 3 and 2 8 km for the analysed section of the irati formation

an esr study on the irati oil shale kerogen abstract esr parameters were measured for the ceri 1 stratigraphic column of the irati formation parana basin brazil in order to verify the anomalous behaviour of the stratigraphic function of paleotemperature observed for the same column by costa neto et al 1978 and contradicted by correa da silva and conford 1985 the good correlation observed between stratigraphic functions of esr and of thermal alteration index tai confirms the results reported by costa neto et al 1978

supposed permo triassic megashear between laurasia and gondwana a consensus has emerged that during the palaeozoic several landmasses progressively collided to form the supercontinent pangaea which subsequently split up in the mesozoic and tertiary to produce the present array of continents but whereas there is a high measure of agreement about the general shape of the early jurassic pangaea shortly before the initial atlantic opening three very different reconstructions of the end palaeozoic supercontinent have recently been proposed these differences which involve the relative positions of the northern and southern sectors of pangaea known respectively as laurasia and gondwana relate to the interpretation of palaeomagnetic data the three constructions are here tested with reference to geological and palaeobiogeographic data and arguments

an unusual hadrosaurid braincase from the dinosaur park formation and the biostratigraphy of parasaurolophus ornithischia lambeosaurinae from southern alberta the lambeosaurine hadrosaurid parasaurolophus is known from rare occurrences in campanian deposits of western north america a previously undescribed large hadrosaurid braincase from the dinosaur p

ceratopsia increase history and trends1 the taxonomic history of the ceratopsia began in 1876 with the description of monoclonius crassus cope followed in 1889 by triceratops horridus marsh after a peak of discovery and description in the 1910s and 1920s resulting from the canadian dinosaur rush in the province of alberta and the central asiatic expeditions to mongolia of the american museum of natural history the study of ceratopsians declined to a low level until the 1990s when discoveries in china montana utah alberta and elsewhere abetted by increased biostratigraphic and phylogenetic precision led to an unprecedented resurgence of activity even richard c fox along with colleagues from peking university joined in the activity by naming psittacosaurus lujiatunensis to place the activity in historical perspective half of all known ceratopsians have been described since 2003 despite important finds of basal ceratopsians in china mongolia and korea north america continues to dominate ceratopsian especially ceratopsid diver

glacial interglacial variation in organic carbon burial on the slope of the n w european continental margin 48 50 n the sources and fate of organic carbon corg were examined at two sites on the goban spur and a single site within the porcupine sea bight on the n w european slope between 48 n and 50 n here we present data on the sedimentary corg concentration its 13c 12c composition 13corg and corg n of 224 total and 119 fine fraction 63 m samples as a time series running from the instantaneous marker horizon heinrich layer 2 25 5 ka bp through the last glacial isotope stage 2 and interglacial isotope stage 1 to the present the significance of the n w european slope as a depositional sink for corg has declined in the past twenty thousand years with flux values decreasing two to three fold from the late glacial 60 70 mg c cm 2 ka 1 to low late holocene values significant shifts are seen in the 13corg signature of both the total and fine fractions between the present interglacial and last glacial the open slope of the goban spur is characterised by relatively low values over the last glacial with minimum values for the total sediment of around 24 5 occurring at ca 18 ka bp and generally increasing values during the holocene with the most recent samples having values of ca 19 2 to 20 2 in the porcupine sea bight a different relationship is evident with samples from the last glacial maximum being generally higher while values from the holocene are lower with a minimum of 23 3 occurring just below the mixed layer similar trends are observed in the fine fraction albeit with a different dynamic range paired analysis of 13corg and corg n are consistent with the organic matter being a climatically forced mixture from c3 photosynthetic terrigenous and marine organic matter sources an increased influence of terrestrial corg is suggested on the glacial goban spur and holocene porcupine sea bight and vice versa we suggest that this may be explained by modern wind driven flushing of terrigenous carbon across the armorican and celtic shelves to the n w and thence into porcupine sea bight during the last glacial increased strength of westerly winds created a residual current regime driving material to the s w where it was transported in vigorous tidal off shelf flushing to the upper slope followed by slope current transfer to the goban spur much of this material was presumably delivered by the great channel river to the outer shelf thus leading to enhanced flux of terrestrial corg on the goban spur the influence of a freshwater plume from meltwater discharge of the european ice sheet in this region is supported by foramininiferal 18o data from which a palaeo salinity reconstruction shows a greatest negative anomaly of 2 55 that is s 35 at the time of maximum terrestrial corg content in the sedimentary material in addition to showing that surface waters over goban spur were relatively fresh throughout the glacial our results also reveal variability in surface salinity on shorter timescales

chronology for climate change developing age models for the biogeochemical ocean flux study cores we construct age models for a suite of cores from the northeast atlantic ocean by means of accelerator mass spectrometer dating of a key core bofs 5k and correlation with the rest of the suite the effects of bioturbation and foraminiferal species abundance gradients upon the age record are modeled using a simple equation the degree of bioturbation is estimated by comparing modeled profiles with dispersal of the vedde ash layer in core 5k and we find a mixing depth of roughly 8 cm for sand sized material using this value we estimate that age offsets between unbioturbated sediment and some foraminifera species after mixing may be up to 2500 years with lesser effect on fine carbonate 10 mu m ages the bioturbation model illustrates problems associated with the dating of instantaneous events such as ash layers and the heinrich peaks of ice rafted detritus correlations between core 5k and the other cores from the bofs suite are made on the basis of similarities in the downcore profiles of oxygen and carbon isotopes magnetic susceptibility water and carbonate content and via marker horizons in x radiographs and ash beds

late pleistocene holocene marine conditions in the ross sea antarctica evidence from the diatom record statistical analyses of diatom assemblages from radiocarbon dated sediment cores were used to reconstruct changing palaeoceanographic conditions in the western and west central ross sea antarctica from c 12 14c kyr bp to the present data from three kasten cores support a north to south time transgressive glacial interglacial transition assemblages at the base of each core suggest that glacial processes affecting frustule preservation were significant during the late pleistocene increasing biogenic silic and decreasing per centages of reworked species suggest that upper water column productivity instead of preservational processes increasingly dominates diatom assemblages during grounding line recession c 12to c 6 14c kyr bp a warm ing during the middle to late holocene c 6to c 3 14c kyr bp may have resulted in a spring sea ice melting prior to the annual inception of the ross sea polynya in the west central ross sea and b increased plateletice delivery due to increased melting beneath t

influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter comparative exercise using data from the qualifying system for reflectance analysis working group of iccp the development of a qualifying system for reflectance analysis has been the scope of a working group within the international committee for coal and organic petrology iccp since 1999 when j koch presented a system to qualify vitrinite particles according to their size proximity to bright components and homogeneity of the surface after some years of work aimed at improving the classification system using photomicrographs it was decided to run a round robin exercise on microscopy samples the classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites this paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed results indicated that the reflectance of particles classified as excellent good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed the differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants overall satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed this was so for samples having abundant and easy to identify vitrinites higher plant derived organic matter as well as for samples with scarce and difficult to identify particles samples with dominant marine derived organic matter the highest discrepancies were found for the organic rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult special instructions should be provided for the analysis of this sort of samples the certainty of identification of the vitrinite associated with the vitrinite reflectance values reported has been assessed through a reliability index which takes into account the number of readings and the coefficient of variation the same statistical approach as that followed in the iccp vitrinite reflectance accreditation program for single seam coals has been used for data evaluation the results indicated low to medium dispersion for 17 out of 22 participants this combined with data from other sets of comparative analyses over a long period is considered an encouraging result for the establishment of an accreditation program on vitrinite reflectance measurements in dispersed organic matter

non steady state 210pb flux and the use of 228ra 226ra as a geochronometer on the amazon continental shelf the recovery of quasi cyclic 210pb profiles from the foreset region of the amazon subaqueous delta has raised questions concerning the non steady state flux of 210pb to this region of the shelf radioisotopic profiles 210pb 234th 228ra 226ra 137cs from seven kasten cores along with the analysis of grain size organic carbon and clay sized mineralogy are used to investigate the time scale and the controlling mechanisms of the 210pb cyclicity a common assumption used in 210pb geochronology is that the initial specific activity is constant with time an assumption that is invalid in this region variations of particle affinity for 210pb have been shown to affect the initial specific activity reaching the seabed in various other studies however investigations of grain size organic carbon and mineralogy have revealed no relationship with the fluctuating 210pb activity in this area a new geochronometer 228ra 226ra is used to determine sediment accumulation rates over a 30 year time scale which range from 10 to 60 cm yr in the study area spectral analysis of the 210pb cyclicity has revealed that the major component of 210pb cyclicity has a frequency of approximately 2 3 years in addition components of the 210pb cyclicity occur on annual and semi annual frequencies the controlling mechanism for the 210pb cyclicity on these time scales appears to be the seaward transport and accumulation of low activity fluid muds from the topset region

carbon burial rates in sediments and a carbon mass balance for the herbert river region of the great barrier reef continental shelf north queensland australia the largest century scale carbon reservoir in the herbert river sector of the great barrier reef continental shelf is carbonate carbon this carbonate carbon is produced by corals coralline algae and other benthic organisms and is stored on less than 13 of the area of the shelf maximum organic carbon burial rates 1 28 mol m 2 yr 1 occur within a wind protected 20 m water depth embayment 1 area of the shelf where the highest bulk sedimentation rates 1 12 kg m 2 yr 1 were determined from 210pb and137 cs profiles in 1 4 m cores sediment organic carbon oc and carbonate carbon cc accumulation rates are very low in the great barrier reef lagoon shelf and slope where most annual productivity 8 15 mol oc m 2 yr 1 is decomposed by algal and microbial respiration a carbon mass balance indicated that approximately 1 of combined river and marine organic carbon production was preserved in across shelf sedimentation but 3 of river and mangrove organic carbon input was preserved in this small wind protected embayment an across shelf carbon mass balance model predicted average shelf organic matter respiration correctly and the ratio of organic carbon fixation to respiration corrected for burial losses was 1 06

geochemical evidence for lacustrine microbial blooms in the vast permian main karoo parana falkland islands and huab basins of southwestern gondwana early permian black pyritic shale units i e the whitehill irati and huab formations and black rock member in southwestern gondwana basins have elevated 13c values of total organic carbon up to 17 pdb hydrogen indices between 300 and 1000 mg co2 g c and oxygen indices 30 mg co2 g c these data suggest a manifestation of a microbial bloom event values for 13c between 26 and 22 pdb hydrogen 100 mg co2 g c and oxygen indices of total organic carbon above and below these rock units are typical for palaeozoic terrestrial type iii organic matter carbon 13 isotope stratigraphy concur with palaeontological evidence that these formations are stratigraphical equivalents and therefore that the microbial blooms covered a vast area 5 million km2 possibly earth s most expansive microbial bloom the palaeoenvironment of the rock units preceding and including the black shales was most likely lacustrine with fresh to brackish water as shown by stable isotope c o and s evidence from organic matter carbonates and pyrite the implication is that a broad tectonic belt which formed as a result of compressional tectonics during the late carboniferous to early permian from the palaeo west must have been sufficiently well developed to cut off any contact with seawater earlier than predicted late permian from previous stratigraphic and sedimentological studies stable isotope data supported by mineralogical evidence indicate that conditions particularly in the upper portions of the lacustrine oil shales were brackish and locally may have been evaporitic we envisage that the microbial blooms possibly botryococcus peaked in the upper half of the black shale units conditions rapidly became unfavourable for microbial blooms across the entire basin in the overlying formations manifested by a change from oil shales type i organic matter to organic poor type iii shales this may possibly have been a consequence of tectonic activity and interrelated causes stable isotope data of carbonates in the overlying sediments indicate that in the palaeo north the basin became evaporitic drying up and in the palaeo southern part of the basin high latitude altitude water flooded the basin and so brought to a close the microbial blooms

paleoreconstruction by biological markers abstract during diagenesis and conversion of the original lipid fraction of biological systems to petroleum hydrocarbons the following four basic events needed for paleoreconstruction can be monitored by biological markets 1 sourcing 2 maturation 3 migration and 4 biodegradation actual cases of applying biological markers to petroleum exploration problems in different parts of the world are demonstrated cretaceous and phosphoria sourced oils in the wyoming thrust belt can clearly be distinguished from one another by high quality source fingerprinting of biomarker terpanes using gas chromatography mass spectrometry identification of recently discovered biological markers head to head isoprenoids allows subtle source differentiation between oils from sumatra the degree of crude oil maturation in basins from california alaska russia wyoming and louisiana can be assessed by specific novel biomarker ratios 20s 20r sterane epimers field evidence from such interpretation is confirmed by laboratory pyrolysis of the rock an example of immature sumatra rock is given extensive migration is documented by biomarkers in several oils the effect of biodegradation on biomarker steranes and terpanes is exemlified in a california basin all biological marker results are consistent with the geological setting and add a new dimension in assisting the petroleum explorationist toward paleo reconstruction

natural flux of greenhouse methane from the timor sea to the atmosphere 1 methane gas bubbles from the cornea seep were sampled at the sea surface in the timor sea continental shelf area in june 2005 total bubble gas flux was 0 076 to 0 76 l m 2 h 1 during the 6 h d 1 periods of low neap tides in june 2005 this bubble gas contained an average of 26 mmol ch4 l 1 and about 0 16 and 0 006 mmol l 1 of ethane and propane we estimate the daily flux from the sea surface to the atmosphere to be 0 012 to 0 12 mol ch4 m 2 d 1 or 0 13 to 1 3 t ch4 d 1 from an area of about 0 7 km2 this methane flux came from a 500 1400 m carbonate pavement dome on the seafloor at 84 m water depth the seep hard ground was swath mapped and 3 5 khz subbottom profile data indicate that the seep dome was strongly reflective with poor penetration into the subsurface consistent with the presence of a carbonate hard ground carbon and deuterium isotope ratios 13c 41 to 42 d 157 to 158 of the seep bubble gas indicate that this methane had a thermogenic origin and was in the same isotopic range as gas within the late cretaceous cornea oil and gas field we could not detect inputs of fluids containing nutrients or short lived radium isotopes at this site commonly associated with other cold seeps tens to a hundred of kilometers seaward from the cornea seep site water column dissolved methane concentrations in this sector of the timor sea shelf and slope were 100 500 times supersaturated with respect to the atmosphere and thus the water column is expected to be degassing additional methane to the atmosphere perhaps there are thousands of other methane seeps of similar magnitude to the cornea seep on this shelf and slope to account for all the excess dissolved methane 86 000 t measured in the water column these measured and calculated fluxes provide evidence for the hypothesis that shallow sea seeps may be a significant source of atmospheric methane in contrast to deep sea vents where most of the methane is dissolved and oxidized in seawater and does not reach the atmosphere

origin of nama basin bitumen seeps petroleum derived from a permian lacustrine source rock traversing southwestern gondwana abstract biodegraded bitumens associated with quartz and calcite veins in the cambrian fish river subgroup sediments of the nama group of southern namibia have a geochemical signature diagnostic for organic matter that was deposited in a saline lacustrine palaeoenvironment in particular they contain abundant gammacerane carotane and 3 methylhopanes while 24 isopropyl cholestanes and dinosteroids are not detectable sealed tube hydrous pyrolysis of asphaltene and polar fractions yielded saturated hydrocarbons amenable to c isotopic analysis and these analyses show unusually low 13 c values these combined characteristics are also present in immature bitumens from the permian irati formation of brazil and a saline lacustrine facies of the whitehill formation in the karoo basin south africa we conclude that the bitumens originated from whitehill equivalent strata of the kalahari basin deposited in what was an extensive saline lacustrine basin in southwestern gondwana during the early permian in southern africa source rocks of the whitehill formation are generally immature for petroleum generation and it is therefore likely that the nama bitumens were expelled by contact metamorphism during emplacement of karoo dolerite sills and dykes in the jurassic

thermal history of sedimentary basins maturation indices and kinetics of oil and gas generation temperature is the most sensitive parameter in hydrocarbon generation thus reconstruction of temperature history is essential when evaluating petroleum prospects no measurable parameter can be directly converted to paleotemperature maturation indices such as vitrinite reflectance tmax from rock eval pyrolysis spore coloration thermal alteration index tai or concentration of biological markers offer an indirect approach all these indices are a function of the thermal history through rather complex kinetics frequently influenced by the type of organic matter their significance and validity are reviewed besides the problems of identification e g vitrinite and interlaboratory calibration it is important to simultaneously interpret kerogen type and maturation and to avoid difficult conversions from one index to another geodynamic models where structural and thermal histories are connected are another approach to temper ture reconstruction which could be calibrated against the present distribution of temperature and the present value of maturation indices kinetics of kerogen decomposition controls the amount and composition of hydrocarbons generated an empirical time temperature index tti originally introduced by lopatin does not allow such a quantitative evaluation due to several limitations no provision for different types of kerogen and different rates of reactions poor calibration on vitrinite reflectance it is of limited interest unless one has no access to a desk top computer kinetic models based on a specific calibration made on actual source rock samples can simulate the evolution of all types of organic matter and can provide a quantitative evaluation of oil and gas generated examples from the jurassic source rocks of the paris basin monterey formation of california green river shales of utah paleozoic source eds of the algerian sahara and miocene rocks of the mahakam delta indonesia illustrate various aspects of the discussion geological geochemical models are the most efficient way to integrate geological seismic and geochemical data and they should greatly help to reduce the risk in exploration

thermal and depositional history of early permian rio bonito formation of southern parana basin brazil abstract the parana basin is a large volcano sedimentary basin with a complex depositional history from ordovician to the cretaceous period during permian significant amounts of organic rich beds accumulated within the rio bonito and irati formations representing deposition in coastal deltaic and barrier lagoon and shallow marine environments respectively in this work the thermal history of these beds is examined from 16 vitrinite reflectance analyses of coal beds rio bonito formation integrated with previous data on coal rank and 21 apatite fission track aft analyses collected from 17 well profiles in the south of the parana basin coal samples showed three different maturity levels two with reflectances of 0 4 0 6 and 0 6 0 8 rr formed by the natural burial history of the basin the latter is restricted to the torres syncline area in contrast the third group reached much higher values 1 0 5 0 rr related to intrusive igneous rocks the aft data show thermal consistency with the reflectance values the sandstone samples related to the two lower reflectance patterns were partially reset preserving aft ages older than the stratigraphic age of the bed otherwise the samples severely affected by the magmatism have cretaceous and early cenozoic ages but some were much younger than the last magmatic event implying deep burial before cooling onset the mean track length distribution of the partially reset samples is short due to the inheritance of tracks preserved from basement cooling history however the population of fully reset samples gives crucial information on the maximum temperature reached and the age when cooling started at these conditions around 1 0 to 3 0 km of the parana basin sequences would have been removed from the surface of the studied areas by erosion since cretaceous regional variations in the amounts of removed sections were controlled by the structural framework mostly regional nw se and ne sw oriented structures

a basal ceratopsid centrosaurinae nasutoceratopsini from the oldman formation campanian of alberta canada a partial skull cmn 8804 of a ceratopsid from the upper unit of the campanian oldman formation of alberta is the first canadian example of the newly established nasutoceratopsini a new subclade of centrosaurinae defined as the stem based clade of centrosaurine ceratopsids more closely related to nasutoceratops titusi than to centrosaurus apertus the new clade is diagnosed in part by having a parietosquamosal frill lacking modified epimarginals a small nasal horncore large rostrolaterally directed postorbital horncores and a relatively short deep face although the cmn 8804 taxon closely resembles nasutoceratops its phylogenetic position within nasutoceratopsini is unresolved the cmn 8804 taxon would have been contemporaneous with dinosaurs from the lower portion of the dinosaur park formation 200 km to the northwest in dinosaur provincial park the presence of the cmn 8804 taxon in alberta and the approximately contemporaneous nasutoceratops in utah indicates that the nasutoceratopsins pers

sediment dispersal and accumulation off the ayeyarwady delta tectonic and oceanographic controls abstract recent sediment dispersal and accumulation on the northern andaman sea continental shelf off the ayeyarwady irrawaddy and thanlwin salween rivers are investigated using seabed water column and high resolution seismic data collected in december 2017 210pb and 137cs derived sediment accumulation rates are highest up to 10 cm y 1 in the mid shelf region of the martaban depression a basin that has formed on the eastern side of the n s trending sagaing fault where rapid progradation of a muddy subaqueous delta is occurring landward of the zone of highest accumulation in the shallow gulf of martaban is a highly turbid zone where the seabed is frequently mixed to depths of 1 m below the sediment water interface frequent resuspension in this area may contribute to the formation of extensive fluid muds in the water column and consequent re oxidation of the shallow seabed likely reduces the carbon burial efficiency for an area where the rivers are supplying large amounts of terrestrial carbon to the ocean sediment cores from the gulf of martban have a distinctive reddish brown coloration while x radiographs show sedimentary structures of fine silt laminations in mud deposits which indicates strong tidal influences the seaward part of the martaban depression off the modern subaqueous delta is covered by relict sediment with no apparent connection between the modern sediment deposit and the offshore martaban canyon on the western side of the sagaing fault the mouths of the ayeyarwady represent a large promontory where the subaerial delta has prograded seaward some 200 km along the eastern flank of the indo burman range since the holocene maximum transgression the shelf area off the mouths of the ayeyarwady presently exhibits low sediment accumulation rates 1 cm y 1 and a relative coarse sandy texture the reduced accumulation and coarse texture in the western shelf region at the present time is attributed to frequent wave resuspension and subsequent transport of finer river derived sediment eastward into the martaban depression during the sw monsoon a mud drape accumulation rates

glacial interglacial changes in water mass structure and flow in the sw pacific ocean eight to ten point depth profiles from 1200 to 4800 m water depth of oxygen and carbon isotopic values derived from benthic foraminifera averaged over selected times in the past 160 ka are presented the data are from 10 sediment cores off eastern new zealand mainly north chatham rise this lies under the deep western boundary current in the southwest pacific and is the main point of entry for several water masses into the pacific ocean the benthic isotopic profiles are related to the structure of water masses at present and inferred for the past these have retained a constant structure of lower circumpolar deep water upper circumpolar deep water north pacific deep water antarctic intermediate water with no apparent changes in the depths of water mass boundaries between glacial and interglacial states sortable silt particle size data for four cores are also examined to show that the vigour of the inflow to the pacific while variable appears to have remained fairly constant on average among the lowest last glacial maximum values of benthic 13c in the world ocean 1 03 based on cibicidoides wullerstorfi occurs here at 2200 m comparable values occur in the atlantic sector of the southern ocean while those from the rest of the pacific are distinctly higher confirming that the southern ocean was the source for the unventilated nutrient enriched water seen here oxygen and carbon isotopic data are compatible with a glacial cold deep water mass of high salinity but lower nutrient content or better ventilated below 3500 m depth this contrasts with the south atlantic where unventilated nutrient enriched water extends all the way to the sea bed comparison with previous studies also suggests that the deeper reaches of the antarctic circumpolar current below 3500 m are not homogeneous all around the southern ocean with the kerguelen plateau and or the macquarie balleny ridges posing barriers to the eastward spread of the deepest low 13c water out of the south atlantic in glacials these barriers combined with inferred high density of bottom waters restricted inter basin exchange and allow three glacial domains dominated by bottom waters from weddell sea adelie coast and ross sea to be defined we suggest that the ross sea was the main source of the deep water entering the pacific below 3500 m

in situ high temperature esr measurements for kerogen maturation abstract kerogen samples from middle miocene mudstone cores in two japanese exploratory wells have been investigated by an in situ high temperature esr technique anhydrous pyrolysis of the kerogens results in four distinctstemperature stages in spin concentration ns ns increasessin the first and third at end of catagenesis is characterized only by two stages third and fourth these data are based on the formation and recombination of free radicals and have been used to derive parameters related to kerogen maturation and hydrocarbon generation

biological indicators of sedimentary dynamics in the central gulf of papua seasonal and decadal perspectives 1 benthic and pelagic communities in the central gulf of papua a major deltaic clinoform located on the south coast of papua new guinea reflect the spatial and seasonal patterns in physical sedimentation conditions and the availability of food resources across this system the distribution of terrigenous and marine organic substrates the transport of riverine derived sediment and seafloor dynamics are largely controlled by two seasons and wind patterns the relatively quiescent nw monsoon and more energetic se trades the physically disturbed inner topset deposits 20 m are dominated at all times by bacterial biomass and have depressed numbers of macrofauna with evidence of periodic recolonization recorded in sedimentary structures the inner topset region also shows strong seasonality in the production and availability of labile organic matter and in bacterial activity as measured by the concentrations of photopigments and microbial biomass in the upper 2 cm of surface sediments and in the water column the comparatively quiescent nw monsoon period is associated with net delivery of reactive substrates as labile organic matter to the bottom and net growth of the benthic microbial community whereas the transition period between the nw monsoonal winds nw monsoon and se trade winds se trades and the se trades are periods of reactive substrate depletion in bottom deposits and decreased benthic bacterial and macroinfaunal biomass in contrast to the inner topset the less physically disturbed outer topset and foreset show relatively enhanced but still low abundances of large macrobenthos and possible evidence of variation related to food supply the greatest observed seasonal variation in macrofauna occurs in the umuda valley off the fly river an apparent mobile sediment conduit

organic geochemical signals of freshwater dynamics controlling salinity stratification in organic rich shales in the lower permian irati formation parana basin brazil abstract the lower permian irati formation in the northeastern and central eastern parana basin southern brazil was investigated in terms of bulk and molecular organic geochemistry in order to enlighten the complex depositional paleoenvironment during deposition of irati black shales the geochemical data reflect temporal and spatial variations of freshwater incursions promoting salinity stratification and high primary productivity in surface waters with the establishment of photic zone euxinia overall highly concentrated c17 long chain alkylnaphthalenes point to algal blooms as a result of freshwater inflows into the irati sea mostly in the central eastern basin segment and resemble concentration variations of pristane phytane and nc17 the freshwater inflows were also retraced by increasing chroman ratios toward the top of the investigated units along with the general decrease of further palaeosalinity indicators e g gammacerane tetracyclic c24 carotane and the herein suggested carotane and lexane indexes the existence of a water column stratification promoting organic matter preservation is supported by the detection of tetrahydrophenanthrene at high concentrations in addition to the known prominent occurrence of gammacerane the detection of c10 to c31 aryl isoprenoids in addition to c16 and c18 pseudohomologue aryl isoprenoids points to the presence of photic zone euxinia in general samples from the central eastern basin were deposited in a deeper marine setting with lower salinity than samples from the northeastern basin which displays signals of a shallower marine environment with reducing bottom water conditions both deposited under freshwater influxes

a long square barrel gravity corer for sedimentological and geochemical investigation of fine grained sediments abstract large volume undisturbed sediment cores 3 m long are obtained using a modified gravity corer the corer is square in cross section 12 7 12 7 cm and is designed to facilitate acquisition and subsampling of fine grained sediments sedimentological and geochemical data demonstrate that the modified gravity corer obtains undisturbed cores and preserves the sediment water interface

tectonic stratigraphic and sedimentologic significance of a regional discontinuity in the upper judith river group belly river wedge of southern alberta saskatchewan and northern montana the lithostratigraphic interval between the taber and lethbridge coal zones in the upper portion of the nonmarine judith river group of southeastern alberta is divisible into two lithostratigraphic units separated by a regionally extensive and diachronous discontinuity the lower unit referred to here as the oldman formation is characterized by very fine grained to fine grained sandstones that contain fewer than 2 volcanic rock fragments sandstone bodies with numerous sets of horizontally stratified sandstone showing little or no evidence of lateral accretion siliceous paleosols ganisters and a relatively high gamma ray signal in the upper half of the formation the oldman formation comprises deposits of a low sinuosity perhaps ephemeral fluvial system that originated in the southern cordillera of canada and northern montana and flowed northeastward perpendicular to the axis of the alberta basin the upper unit is assigned to a new formation the dinosaur park formation and is characterized by

early diagenetic remineralization of sedimentary organic c in the gulf of papua deltaic complex papua new guinea net loss of terrestrial c and diagenetic fractionation of c isotopes oceania supplies 40 of the global riverine flux of organic carbon approximately half of which is injected onto broad continental shelves and processed in shallow deltaic systems the gulf of papua on the south coast of the large island of new guinea is one such deltaic clinoform complex it receives 4 mt yr 1 particulate terrestrial organic carbon with initial particle corg loading 0 7 mg m 2 corg loading is reduced to 0 3 mg m 2 in the topset upper foreset zones of the delta despite additional inputs of mangrove and planktonic detritus and high net sediment accumulation rates of 1 4 cm yr 1 carbon isotopic analyses 13c 14c of co2 and corg demonstrate rapid 100 yr remineralization of both terrestrial 13c 28 6 and marine corg 13c 20 5 ranging in average age from modern bomb 14c 60 to 1000 yr 14c 140 efficient and rapid remineralization in the topset upper foreset zone is promoted by frequent physical reworking bioturbation exposure and reoxidation of deposits the seafloor in these regions particularly 20 m apparently functions as a periodically mixed suboxic batch reactor dominated by microbial biomass although terrestrial sources can be the primary metabolic substrates at inshore sites relatively young marine corg often preferentially dominates pore water co2 relative to bulk corg in the upper foreset thus a small quantity of young rapidly recycled marine organic material is often superimposed on a generally older less reactive terrestrial background whereas the pore water co2 reflects both rapidly cycled marine and terrestrial sources terrestrial material dominates the slower overall net loss of corg from particles in the topset upper foreset zone i e recycled marine corg leaves little residue preferential utilization of corg subpools and diagenetic fractionation of c isotopes supports the reactive continuum model as a conceptual basis for net decomposition kinetics early diagenetic fractionation of c isotopes relative to the bulk sedimentary corg composition can produce changes in 14c activity independent of radioactive decay in the gulf of papua topset upper foreset 14c of pore water co2 averaged 300 greater than corg sediment between 1 3 m depth in deposits diagenetic fractionation and decomposition aging of sedimentary corg compromises simple application of 14c for determination of sediment accumulation rates in diagenetically reactive deposits

a sediment record of cyclic bottom current variability from the northwest weddell sea cores and 3 5 khz sub bottom profiles collected from the continental slope and rise near 64 s 52 w off the tip of the antarctic peninsula reveal transport and depositional processes in a high energy environment a large channel runs downslope from the shelf break the remaining slope area is smooth and shows no acoustic penetration except locally in the lee of topography sediments on the slope and rise were mainly deposited by suspension from a 150 to 300 m thick nepheloid layer periodic resuspension and winnowing by bottom currents has produced coarse lags of ice rafted debris throughout these deposits and has also produced an elongated field of mudwaves running parallel to the base of the slope these low amplitude asymmetric features were formed by currents flowing from west to east parallel to the local slope short gravity cores show a compositional and textural cyclicity developed between two distinct lithologies intervals of poorly sorted sediment barren of fauna and with mud dominated size distributions are interpreted to result from a cold climate and low bottom current strength production of weddell sea bottom water probably lessened during these times and there was a greater duration of sea ice cover these sediments are interbedded with winnowed and better sorted deposits comprising fine sands and silts that contain abundant planktonic foraminifera interpreted as implying warmer climatic conditions and stronger current activity a varied calcareous benthic foraminiferal assemblage also indicates that these intervals lay above the ccd during deposition renewed and invigorated production of bottom water is implied contemporaneous with a shorter duration of sea ice cover petrographic evidence indicates an antarctic peninsula source throughout the cycles are considered to be the result of climatic fluctuations occurring over the timespan of glacial interstadials although confirmation of this timescale awaits acquisition of an absolute chronology

taphonomy of the danek bonebed a monodominant edmontosaurus hadrosauridae bonebed from the horseshoe canyon formation alberta the danek bonebed horsethief member horseshoe canyon formation late campanian is dominated by the remains of at least 12 edmontosaurus regalis skeletal remains of a tyrannosaurid and ceratopsid are also known the predominantly disarticulated remains were interred on a periodically inundated floodplain and although the cause of death is unknown a sudden catastrophic death explains the demographic spread faunal diversity rare greenstick fractures and homogeneous weathering abrasion categories of the assemblage the danek bonebed shares a similar taphonomic signature to the liscomb bonebed prince creek formation alaska but it is unique among all other described hadrosaurid bonebeds in the unusually high proportion of bite marked bones 30 suggesting scavenging played a major role in the reworking of the assemblage the highest frequency of bite marks is found on small often unidentifiable and commonly ignored bone fragments underscoring the role that such fragments can play in taphono

distribution and sources of particulate organic matter in the water column and sediments of the fly river delta gulf of papua papua new guinea suspended particles from surface and bottom waters and surficial sediments from the seabed were collected throughout the fly river subaqueous delta region during the monsoon season in january 2003 because of the unusually low river discharge associated with a strong el nino water column salinities were relatively high 10 to 32 throughout most of the delta with brackish salinities 4 wt relatively high organic carbon nitrogen molar ratios oc n 20 mol mol and quite depleted stable isotopic compositions of organic carbon 13coc 27 in contrast surface sediments in the seabed displayed spatially uniform compositions that were characterized by markedly lower oc contents 1 1 0 8 wt lower oc n ratios 17 9 mol mol and relatively enriched 13coc compositions 25 5 1 1 the radioisotopic compositions of oc from a selected set of seabed samples 14coc of 408 82 indicate om in surface sediments is old 14c ages of 2800 to over 6000 years before present the ratios of organic carbon to mineral surface area exhibited by these sediments are within the typical mono layer equivalent ranges characteristic of shelf sediments and do not reflect the preferential removal of terrigenous om overall these compositions indicate that while water column pom appears to be derived mainly from terrigenous vascular plant debris and riverine estuarine phytoplankton the source of most of the sedimentary pom is aged soil oc ultimately derived from c3 vegetation we speculate that the concentrations and sources of suspended pom in the water column of the fly river delta region reflect the conditions of low river discharge low wave energy and neap tides encountered at the time of sampling in contrast pom compositions in surface sediments are consistent with the transport and deposition of old mineral bound oc most likely eroded from the upland regions of the fly river watershed which is characterized by steep slopes high precipitation and c3 tropical forests and grasslands

property changes of oil shale during artificial maturation the irati formation from the parana basin brazil abstractacquiring elastic property information from oil shale during pyrolysis remains a difficult endeavor we subject oil shale samples from the irati formation in the parana basin brazil to high temperature high pressure hydrous and anhydrous pyrolysis while simultaneously acquiring p and s waveform data we present elastic properties as a function of temperature at constant differential pressure using samples cored in three different directions relative to the bedding plane hydrous pyrolysis decreased total organic carbon toc in samples from 25 wt to 20 wt whereas anhydrous pyrolysis had no significant change in toc the cores experienced higher strain hysteresis up to 0 094 residual axial strain after hydrous pyrolysis compared to after anhydrous pyrolysis 0 56 residual axial strain the larger residual strain was accompanied by a larger increase in shear velocity up to 35 after hydrous pyrolysis as compared to the 3 shear velocity increase after anhydrous pyrolysis the change coul

esr assessment of kerogen maturation and its relation with petroleum genesis abstract petroleum hydrocarbons are formed by breakdown of kerogen preserved in source rocks throughout the process of catagenesis this process is accompanied by free radical generation in kerogen the availability of measuring free radicals in kerogen using esr to deduce a maturation estimation of potential source rocks has been hindered due to the presence of the solvent extractable organic molecules seom trapped within the kerogen matrix spin concentration ns of the kerogen treated with pyridine k py represents the paramagnetic centers of the kerogen matrix itself and provides a potential parameter to evaluate kerogen maturation

the danek edmontosaurus bonebed new insights on the systematics biogeography and palaeoecology of late cretaceous dinosaur communities1 vertebrate bonebeds are rich sources of palaeontological information throughout the world rogers et al 2007 and they have long been sources of information on dinosaur anatomy behaviour ecology growth and variability although dinosaur dominated bonebeds have been known in alberta for a long time brown 1919 sternberg 1970 they received relatively little attention during the first seven decades that dinosaurs were collected in the province this was primarily because collectors came to alberta for the relatively common well preserved articulated dinosaur skeletons that produced both new species and spectacular museum displays currie 1981 1987 since the beginning of the 1980s the dinosaur bonebeds of dinosaur provincial park have received considerable attention currie and dodson 1984 visser 1986 ryan 1992 andersen 2000 ryan et al 2001 ryan 2003 ryan and russell 2005 eberth and getty 2005 however younger bonebeds from farther north in the province have enjoyed less attention ryan et al 1995 1998 2011 eberth et al 2013 two notable exceptions are the albertosaurus bonebed near dry island buffalo jump provincial park currie and koppelhus 2010 and the pachyrhinosaurus lakustai bonebed along pipestone creek near grande prairie currie et al 2008 in and around edmonton in particular dinosaur remains have been largely ignored in the published literature bell and campione 2014 despite easy access to outcrops along the north saskatchewan river and its associated streams and creeks this special issue of the canadian journal of earth sciences increases our knowledge of edmonton s urban dinosaurs especially the iconic and serendipitously named hadrosaurid

sea bed mixing and particle residence times in biologically and physically dominated estuarine systems a comparison of lower chesapeake bay and the york river subestuary biologically dominated lower chesapeake bay and the physically dominated york river subestuary are contrasted in terms of the dynamics of sediment mixing strata formation and sea bed particle residence times two lower bay sites were examined both are located within the bay stem plains and are characterized by muddy sand and an abundance of large deep dwelling organisms x radiographs indicate extensive biological reworking of sediments with no long term preservation of physical stratification 210pb profiles reveal low sediment accumulation rates at both lower bay sites 80vs6 30 cm2year 1 in contrast the york river site located within a partially filled palaeochannel is predominantly mud with a depauperate benthic community dominated by small short lived shallow dwelling organisms although210pb accumulation rates at the york river site 0 2 cm year 1 are similar to those measured in the lower bay there is little bioturbation in addition transient bed forms at the york river site form laterally persistent linear ridges and furrows sub parallel to the channel spaced 10 20 m apart these observations coupled with evidence of episodic erosion and deposition from radioisotope and porosity profiles and x radiographs suggest that the upper 60 120 cm of the sea bed are dominated by physical mixing deep mixing and low accumulation rates result in long residence times of particles in the mixed upper portion of the sea bed 102year at both locations despite different mixing controls i e biological diffusive vsphysical advective

vertical fluxes of hydrocarbons on the northwest shelf of australia as estimated by a sediment trap study abstract sediment traps were deployed on the northwest shelf nws of australia in november 1996 to determine fluxes of organic matter and inorganic elements from the photic zone to deeper waters transecting the exmouth shelf to exmouth plateau dry weight fluxes from the traps ranged from 124 to 616 mg m 2 day 1 and poc fluxes ranged from 22 8 to 43 9 the biogenic hydrocarbons consisted of biomarkers indicative of marine zooplankton phytoplankton and bacteria gc analyses also revealed a significant component of petroleum derived hydrocarbons through the presence of an unresolved complex mixture ucm that was approximately 4 times the biogenic hydrocarbon flux at shallow stations and up to 7 times at the most offshore station the molecular characteristics of these hydrocarbons were investigated using gc ms and gc ms ms and compared with local and regional petroleum accumulations gc ms analysis showed the hydrocarbons included n alkanes alkylated aromatics plus hopane and sterane biomarkers indicating a mature and moderately degraded crude oil the sterane and triterpane signatures also indicated that the source rock of this oil was marine sediment with a calcareous lithology and of probable mesozoic age commercially exploited oils of similar composition are mostly not known on the nws however there are indications that there is an active petroleum system with some similar characteristics in the southern carnarvon basin as shown by oils of anomalous composition to the chervil north herald and south pepper fields these results indicate that exploration strategies in the region should not be confined to oil reserves based on the upper jurassic dingo claystone source

glacial interglacial paleoenvironments of the eastern atlantic ocean the biogeochemical ocean flux study bofs paleoceanography program the papers in this special section discuss many aspects of paleoenvironmental analysis performed using various proxies on cores collected in the northeastern and tropical eastern atlantic during two cruises in the framework of the nerc biogeochemical ocean flux study program bofs coring of the northern bofs leg was carried out on leg 3 of the 1989 bofs program rrs discovery cruise 184 mccave 1989 forty one cores were taken on a north south transect at about 20 w from the flanks of the mid atlantic ridge 47 n to gardar drift 59 n at water depths between 1150 and 4050 m of these 15 cores were taken using a 3 m long large diameter kastenlot corer designed by zangger and mc cave 199o cruise and core data are given by manighetti et al this issue the southern leg coring was carried out on leg c of the 1990 bofs program rrs charles darwin cruise 53 shimmield 199o forty six cores including 14 using the kastenlot corer were taken along a transect at about 2o w between 18 and 42 n at depths between 3000 and 4900 m and focusing on an area off northwest africa

a new centrosaurine ceratopsid from the oldman formation of alberta and its implications for centrosaurine taxonomy and systematics centrosaurus brinkmani sp nov is distinguished from centrosaurus apertus by key features of its cranial ornamentation including the shape and orientation of the postorbital horn and parietal ornamentation at parietal locus 3 the shape of the parietal ornamentation at locus 2 and the possession of accessory parietal ossifications developed as short spines on the caudal parietal ramus this species is restricted to the oldman formation of southern alberta and is the oldest ceratopsid represented by diagnostic material in canada phylogenetic analysis of the centrosaurinae suggests that the development of spike like ornamentation at the parietal locus 3 parietal locus is inversely related to the development of the p1 parietal ornamentation

effect of anigneous intrusion on oil shale at rundle australia abstract elemental analyses x ray diffraction thermal and isotopic analyses gas chromatography mass spectrometry electron spin resonance nuclear magnetic resonance spectroscopy and demineralizing techniques have been used to evaluate the effect of a small igneous intrusion on rundle oil shale each set of results contributes to an overall appreciation of how in situ pyrolysis of a highly aliphatic kerogen occurs as in previous studies application of a range of methods gives a better understanding than any of the techniques on its own significant conclusions are as follows 1 the shale samples closest to the intrusion contain the least organic matter 2 a micro reservoir for expelled volatiles was identified 1 m below the intrusion 3 the hydrogen deficient carbonaceous residue remaining close to the intrusion produces no oil on further heating and 4 the major effect of the intrusive event was the in situ pyrolysis of the oil shale the severity of alteration decreasing with distance from the contact

seabed dynamics of the inner amazon continental shelf temporal and spatial variability of surficial strata the continental shelf southeast and northwest of the amazon river mouth is overlain by a sediment layer of about a meter in thickness characterized by 210pb profiles consisting of one or more segments with nearly uniform excess activity uniform 210pb activity profiles in shelf environments commonly are a result of intense biological reworking of sediments however biological activity is minimal in this area hence this surficial layer sl is a result either of physical reworking of the sediments or of rapid possibly episodic deposition of sediment factors controlling the formation of the sl were examined during the amasseds project between august 1989 and october 1991 primarily using 210pb t1 2 22 3 yr activity profiles and x radiography the thickness and character of the sl were assessed at four locations reoccupied during four seasonal periods corresponding to various riverine and oceanographic conditions e g discharge stage wind stress one of these stations was reoccupied during semidiurnal and fortnightly periods additionally replicate sediment cores were obtained at stations in order to assess small scale spatial variability of geochemical and sedimentological characteristics in the seabed the sl thicknesses in replicate sediment cores obtained at each site were found to vary within 5 cm normalized thickness of the sl decreased by an average of 17 cm between august 1989 and february 1990 a period of increasing wind stress during falling to rising river discharge the sl thickness subsequently increased slightly 8 cm from february to may 1990 and increased again 27 cm between may 1990 and october 1991 the maximum sl thicknesses were observed in october a period of low wind stress and minimal river input suggesting that the observed seasonal changes are dictated by oceanographic conditions as well as by sediment discharge variations in sl thickness are reflected by changes in suspended sediment mostly as fluid muds as the highest suspended sediment inventories and most extensive fluid muds are observed during the period when sl thickness is at a minimum although a significant sl was present during all of the sampling periods changes in the character of 210pb profiles at two of the stations suggest that substantial perhaps complete removal and redeposition of the sl occurred some time between february and may preserved strata i e below the sl is characterized by greater evidence of bioturbation and increased sand content but otherwise is similar to that of the sl long term preservation of strata is thought to occur through episodic suspension and redeposition of the sl with net accumulation of decimeter thick hiatus bounded layers

comparing contiguous high and low elevation continental margins new u th he constraints from south brazil and an integration of the thermochronological record of the southeastern passive margin of south america abstract the southeastern coast of south america is an example of the complexity of passive continental margins as it displays both high and low elevation segments despite sharing a similar pre rift geological history and structural configuration as such it is a prime candidate for investigating debated questions concerning the evolution of passive margins such as the tectonic mechanisms driving uplift their relationship to rifting and continental break up and why some margins are elevated when others are not in this contribution we present new u th he data from a low altitude portion of the south american passive margin in south brazil the sul rio grandense shield and interpret it in the context of the regional thermochronological record new results produce widespread apparent ages and reveal a complex exhumation history from the early paleozoic onwards including reheating during paleo mesozoic sedimentation for most of the study area however final exhumation was achieved at the latest during the rifting and early opening of the south atlantic ocean 135 ma to 100 ma in spite of the presence of major neoproterozoic shear zones the inherited ne sw structural framework seems not to have strongly influenced the thermochronological record the new data were integrated into a large compilation of apatite fission track and u th he results from southeast south america in order to compare regional trends and investigate possible tectonic controls in the exhumation history low elevation areas of the passive margin consistently record complex pre rift cooling histories while high elevation areas experienced significant upper cretaceous paleogene uplift associated with the reactivation of neoproterozoic shear zones because the inherited structural features of both segments are similar plate dynamics alone cannot be responsible for the variating response hence mantellic processes associated with post rift alkaline magmatism may have affected the contrasting exhumation histories this process was probably controlled by important south atlantic fracture zones

magnetostratigraphic and biostratigraphic correlation of late campanian and maastrichtian marine and continental strata from the red deer valley to the cypress hills alberta canada two stratigraphic sequences red deer valley and cypress hills sections in alberta spanning the late campanian to paleocene are magnetostratigraphically and biostratigraphically characterized the red deer valley section had previously been studied but additional material has allowed the extension of the magnetozonation downwards into the bearpaw formation higher sample resolution has allowed the identification of a number of magnetosubzones in 32n 32r and 33n four reversed magnetosubzones have been identified in magnetozone 32n in addition to the one presently recognized in geomagnetic polarity time scales one normal subzone in 32r and one reversed subzone in 33n have also been recorded the 32r 33n boundary is shown to occur in the baculites cuneatus zone the campanian maastrichtian boundary is indicated to be at or near the baculites eliasi baculites baculus boundary at the top of 32n comparisons of the biostratigraphy between the two areas indicate that palynomorph ranges differ from data p

thermal alteration of cretaceous black shale by diabase intrusions in the eastern atlantic ii effects on bitumen and kerogen abstract the thermal effects of three one major and two minor miocene diabase intrusions on cretaceous black shales from dsdp site 41 368 have been analyzed a concentration gradient was observed especially for the hydrocarbons decreasing towards the major intrusion and between the three sills the thermally altered samples in the proximity of and between the sills contained elemental sulfur and an excess of thermally derived pristane over phytane whereas the unaltered sediments contained no elemental sulfur and more phytane than pristane a maximum yield of the extractable hydrocarbons was observed at a depth of 7 m below the major sill two classes of molecular markers were present in this bitumen suite the first was sesqui di and triterpenoids and steranes which could be correlated with both terrigenous and autochthonous sources they were geologically mature and showed no significant changes due to the thermal stress the second class was found in the altered samples which contained only polynuclear aromatic hydrocarbons with low alkyl substitution and sulfur and oxygen heterocyclic aromatic compounds these compounds were derived from pyrolytic reactions during the thermal event kerogen was isolated from all of these samples but only traces of humic substances were present the h c n c 13 c 34 s and d all exhibit the expected effects of thermal stress the kerogen becomes more aromatized and richer in 13c 34s and d in the proximity of and between the sills maturation trends were also measured by the vitrinite reflectance and electron spin resonance where the thermal stress could be correlated with an elevated country rock temperature and an increased degree of aromaticity the effects of in situ thermal stress on the organic rich shales resulted in the generation and expulsion of petroliferous material from the vicinity of the sills

a new ceratopsid from the foremost formation middle campanian of alberta xenoceratops foremostensis gen et sp nov a new centrosaurine ceratopsid from the foremost formation campanian of alberta is described based on frill material from at least three adult sized individuals collected from a low density bone bed the material can be assigned to centrosaurinae based on features of the preserved squamosal although the parietals are incomplete the shape of the diagnostic parietal can be inferred from several overlapping serial elements the parietal of the new taxon shares with all other centrosaurines except centrosaurus apertus spike like ornamentation at the posterolateral p3 locus under traditional coding methods at approximately 78 ma it is the oldest known canadian ceratopsid approximately 0 5 ma older than albertaceratops from the lower oldman formation of canada and approximately 1 0 ma younger than diabloceratops from the wahweap formation of utah a phylogenetic analysis resolves the new taxon as the basalmost centrosaurine and places centrosaurus brinkm

deep flow in the madagascar mascarene basin over the last 150 000 years the sw indian ocean contains at least four layers of water masses with different sources deep antarctic lower circumpolar deep water flow to the north midwater north indian deep water flow to the south and upper circumpolar deep water to the north meridional convergence of intermediate waters at 500 1500 m and the shallow south equatorial current flowing west sedimentation rates in the area are rather low being less than 1 cm ka 1 on madagascar ridge but up to 4 cm ka 1 at amirante passage bottom flow through the madagascar mascarene basin into amirante passage varies slightly on glacial interglacial time scales with faster flow in the warm periods of the last interglacial and minima in cold periods far more important are the particularly high flow rates inferred from silt grain size which occur at warm to cold transitions rather than extrema this suggests the cause is changing density gradient driving a transiently fast flow corroboration is found in the glacial interglacial range of benthic d18o which is ca 2 suggesting water close to freezing and at least 1 2 more saline and thus more dense glacial bottom waters than present significant density steps are inferred in isotope stage 6 the 5e 5d and 5a 4 transitions oxygen isotope data suggest little change by mixing in glacial bottom water on their northward path benthic carbon isotope ratios at amirante passage differ from glacial southern ocean values due possibly to absence of a local productivity effect present in the southern ocean

a redesigned kasten core barrel and sampling technique abstract a modified kasten core barrel was developed to obtain cores with nearly 100 sediment retrieval while minimizing disturbance of the sediment water interface one side of the 15 15 cm square barrel is doubled by a second movable plate which can be moved upwards by a series of hand screws thus enabling complete sideways extrusion of the core this produces a set of subcores or slabs of equal quality with preserved stratigraphy which can be x rayed subsampled stored or frozen for geochemical studies the new kasten core barrel is effective in rough weather inexpensive to build easy to handle and enables fast core processing on board

uranium geochemistry on the amazon shelf evidence for uranium release from bottom sediments in amazon shelf waters as salinity increases to 36 5 10 3 dissolved uranium activities increase to a maximum of 4 60 dpm 1 1 this value is much higher than the open ocean value 2 50 dpm 1 1 indicating a source of dissolved uranium to shelf waters in addition to that supplied from open ocean and riverine waters uranium activities are much lower for surface sediments in the amazon shelf seabed mean 0 69 09 dpm g 1 than for suspended sediments in the amazon river 1 82 dpm g 1 data suggest that the loss of particulate uranium from riverine sediments and the consequent input of dissolved uranium to shelf waters is probably the result of uranium desorption from the ferric oxyhydroxide coatings on sediment particles and or uranium release by mobilization of the ferric oxyhydroxides the total flux i e riverine flux plus desorbed remobilized particulate flux of dissolved 238u from the amazon shelf about 1 2 1015 dpm yr 1 constitutes about 15 of uranium input to the world ocean commensurate to the amazon river s contribution to world river water discharge approximately 18 measurement of only the riverine flux of dissolved 238u underestimates by a factor of about 5 the flux of dissolved238u from the amazon shelf to the open ocean

polycyclic aromatic hydrocarbon distribution within lower hudson river estuarine sediments physical mixing vs sediment geochemistry abstract sediments and porewaters from two cores one from the east river new york and one from newark bay new jersey were sampled for polycyclic aromatic hydrocarbons pahs and other geochemical markers including 210 pb specific activities despite what appears to be similar sources of pahs to sediments within each core as inferred by ratios of alkylated to non alkylated pahs and pah isomer ratios sediments and associated pahs have undergone distinctly different depositional processes at each site sediments from the core in the east river appear to have been subject to intense physically driven resuspension resulting in selective depletion of low molecular weight pahs within the core presumably due to processes such as enhanced desorption and scouring of particle surfaces although sediment pah concentrations were higher in the east river core compared to the newark bay core porewaters were depleted of the majority of pahs analysed in the east river core relative to the newark bay core precluding quantifying sediment porewater pah distribution coefficients in this core sedimentary variables such as c n ratio particle surface area and sedimentary soot carbon were not related to organic carbon normalized pah distribution coefficients k oc obs rather in the core from the newark bay site k oc obs were influenced by sediment mixing and porewater dissolved organic carbon doc results indicate that in urban coastal areas the physical factors influencing time scales of sediment resuspension and deposition may be of primary importance over particle geochemistry in determining whether pahs will likely equilibrate between sediments and pore waters

occurrence of organic matter rich deposits middle jurassic to lower cretaceous from qalikuh locality zagros basin south west of iran a possible oil shale resource abstract organic rich deposits of qalikuh locality zagros basin southwest of iran are unconventional hydrocarbon resources considered as an oil shale which is hosted within a carbonate succession with the age range of middle jurassic to lower cretaceous leco carbon rock eval vi and modified fischer assay analysis were performed on some outcrop samples of these resources to investigate the occurrence of oil shale in the studied samples mean total organic carbon toc is 17 3 wt and the average of petroleum genetic potential s1 s2 is 98 kg hc t rock furthermore toc has direct relationship with petroleum genetic potential hydrogen index hi tmax diagram indicates that the organic matter corresponds to type ii kerogen of probable marine origin with high quality of oil generation according to rock eval data and bitumen reflectance brr the samples are thermally early mature based on the studied samples oil yield of the qalikuh oil shales ranges from 6 1 to 7 9 wt mean oil gas ratio is 2 7 and mean oil yield is 56 7 l t rock according to the observations the production value of qalikuh oil shale is more or less similar in the entire studied regions whereas the total production is below the expected values the produced oil is considerably lighter higher api than that of most other known oil shales

molecular carbon isotope variations in core samples taken at the permian triassic boundary layers in southern china stable carbon isotope composition 13c of carbonate sediments and the molecular biomarker characteristics of a continuous permian triassic pt layer in southern china were studied to obtain geochemical signals of global change at the permian triassic boundary ptb carbonate carbon isotope values shifted toward positive before the end of the permian period and then shifted negative above the ptb into the triassic period molecular carbon isotope values of biomarkers followed the same trend at and below the ptb and remained negative in the triassic layer these biomarkers were acyclic isoprenoids ranging from c15 to c40 steranes c27 dominates and terpenoids that were all significantly more abundant in samples from the permian layer than those from the triassic layer the triassic layer was distinguished by the dominance of higher molecular weight waxy n alkanes stable carbon isotope values of individual components including n alkanes and acyclic isoprenoids such as phytane isop c25 and squalane are depleted in 13c by up to 8 10 in the triassic samples as compared to the permian measured molecular and isotopic variations of organic matter in the pt layers support the generally accepted view of permian oceanic stagnation followed by a massive upwelling of toxic deep waters at the ptb a series of large scale global outgassing events may be associated with the carbon isotope shift we measured this is also consistent with the lithological evidence we observed of white thin clay layers in this region our findings in context with a generally accepted stagnant permian ocean followed by massive upwelling of toxic deep waters might be the major causes of the largest global mass extinction event that occurred at the permian triassic boundary

a classification of petroleum on the basis of the ratio of sulfur to nitrogen abstract examination of the ratio of organic sulfur to organic nitrogen s n in 455 petroleums shows that individual petroleum families selected geographically stratigraphically and by source exhibit distinctive limited ranges of the value of this ratio commonly observed values in petroleums are between 1 and 20 the coefficient of variation within a family is frequently 100

sedimentary structures on the bengal shelf a multi scale approach to sedimentary fabric interpretation abstract sedimentary structures on the bengal shelf are examined using x radiographic thin section and scanning electron microscopic sem techniques which reveal contrasting depositional processes for the inner and middle shelf as well as for either side of a major submarine canyon indenting the western shelf margin the inner shelf is characterized by tidally produced interlaminated silts and muds that reveal a neap spring cyclicity the cyclicity is more pronounced for the winter season when high discharge monsoon conditions do not obscure the tidal signature on the middle shelf alternating beds of silts and muds probably represent high discharge and low discharge conditions respectively silty beds on the western margin of the submarine canyon are thinner than those found on the eastern margin the western margin receives predominantly fine grained ganges sediments in contrast to the eastern area which receives both ganges and coarser brahmaputra sediments these observations indicate that the submarine canyon presently intercepts westward along shelf sediment transport muddy beds and laminae that appear internally homogeneous in the x radiographs and exhibit faint bedding in thin sections often are composed of resistant protruding and less resistant recessed microlaminae as observed with the sem on the inner shelf resistant microlaminae are composed of fine grained polymineralic equant particles the less resistant microlaminae are composed of large platy illite grains rimmed by smaller platy or lath like illite particles resistant and less resistant microlaminae within middle shelf muddy sediments have the same textural characteristics observed on the inner shelf however both types essentially are monomineralic on the middle shelf the smallest particles within the less resistant microlaminae exhibit an open flocculated structure that may result from higher salinity and or decreased bottom shear stress associated with tidal currents biological structures predominantly occur on the western inner and middle shelf particularly in intervals of high smectite concentrations this relationship may exist because of a preferential organic affinity for expandable minerals providing a favorable substrate for benthic organisms

analysis and modelling of gravity and piston coring based on soil mechanics the effects of gravity and piston corers on the dimensional accuracy of marine sediment cores is analysed using principles of soil mechanics a model for the coring process is built around the feedback that arises and develops between the core barrel and the sampled sediment this model for sediment response is applied to different hypothetical coring scenarios which are then compared to real examples providing insights into the specific effects of each sampling method and the development of these effects down core four cores from a single location on the iberian margin are found to contain stratigraphically intact successions that differ in length by a factor of up to 2 7 due solely to the different effects of each coring method these dimensional discrepancies are attributed to the combined effects of over sampling in the upper portions of the piston cores due to cable rebound causing upward piston acceleration and under sampling dominant in the basal portions of the open barrel gravity type cores it is suggested that heavier piston corers deployed on longer lighter cables are prone to greater over sampling ratios over longer stratigraphic intervals due to the increased likelihood and extent of cable rebound cable rebound may also give rise to double penetration of gravity corers resulting in repeated stratigraphic intervals knowledge of the dimensional accuracy of marine sediment cores is essential to an evaluation of past sedimentation rates and hence interpretations of past depositional processes it is therefore essential that we recognise the sampling effects of each coring method and their variability down core lest coring artefacts be interpreted as sedimentary signals different core types may be more suited to different palaeoceanographic investigations hence failing the development of a practical cable deployed recoilless piston corer a combination of a variety of core types will permit the best acquisition of the in situ stratigraphic truth our results suggest that a large diameter dc 20 30 cm square barrel gravity corer for the top 10 12 m combined with a cylindrical piston corer below 10 m may provide the least deformed material

long hydroplastic plastic barrel sediment cores suitable for geotechnical testing abstract long large diameter 8 cm sediment cores are obtained by outfitting the pvc core barrels with a sliding weight placed near its bottom no metal barrel is needed laboratory tests prove that the cores thus obtained are undisturbed and suitable for geotechnical testing

early diagenetic cycling incineration and burial of sedimentary organic carbon in the central gulf of papua papua new guinea 1 the clinoform complex of the gulf of papua represents a major deltaic system in oceania two seasons largely control seafloor dynamics and sedimentary c cycling the relatively quiescent nw monsoon and the se trades characterized by remobilization and reoxidation of topset deposits surface sediments 20 cm are reactive with co2 production fluxes 35 42 mmol m 2 d 1 at mangrove channel and topset sites during the monsoon and 10 20 mmol m 2 d 1 on the foreset bottomset 40 m fluxes decrease by a factor of 0 3 on the topset during the transition period and trades the 13 14c isotopic compositions of pore water co2 reveal diagenetic fractionation with dominant utilization of young 14c 1 4 31 1 terrestrial c substrates inshore channels topset 13c 29 to 25 and a progressive increase of young marine c sources seaward outer topset foreset bottomset 13c 22 2 to 19 5 remineralization patterns of terrestrial and marine corg demonstrate cross shelf exchange multiple tracers show that a suboxic mobile mud layer 10 60 cm thick usually 10 30 cm characterizes the central gulf topset and umuda valley off the fly river and unconformably overlies methanic deposits releasing old co2 14c 159 to 229 residual terrestrial corg delivered to the bioturbated foreset continues to be remineralized slowly generating co2 having net 14c 270 within sediments deposited 100 200 years ago the reactivity of corg below 0 5 m in the foreset is 10 20 times lower than expected based on accumulation rates reflecting loss of 50 of sedimentary corg on the topset which functions as a suboxic incinerator

the first radiometric ages from the judith river formation upper cretaceous hill county montana a new isotopic age of ca 78 ma was obtained by the conventional k ar method and by laser fusion 40ar 39ar analysis of biotite and sanidine crystals from two bentonites in the judith river formation of kennedy coulee hill county montana the 40ar 39ar analyses yielded weighted mean ages of 78 2 0 2 ma biotite and 78 2 0 2 ma sanidine for sample 84mg8 3 4 and 79 5 0 2 ma biotite and 78 5 0 2 ma sanidine for sample 85mg7 16 1 these are the first isotopic age determinations from the judith river formation the dated bentonites in kennedy coulee bracket two significant judithian age mammal localities ucmp v77083 and v81234 the radioisotopic age of ca 78 ma for the hill county local faunas and correlations of other judithian local faunas with marine units suggest that the duration of the judithian was at least 5 ma judithian local faunas are probably correlative with the late campanian of the western interior similarities in the principal judithian mammalian faunas from alberta monta

gc ms characterisation of c27 and c28 triterpanes in sediments and petroleum abstract earlier studies have shown that an unusual c 27 triterpane is abundant in sediments from the norwegian continental shelf and the north sea this compound was assigned the tentative structures 24 28 30 trisnormoretane or 25 28 30 trisnormoretane but we have now shown from detailed retention time measurements and a reinterpretation of the mass spectral data that its correct structure is 17 h 18 h 21 h 25 28 30 trisnorhopane two other triterpanes 25 28 30 trisnormoretane and 28 30 bisnormoretane have also been identified as minor constituents of extracts of sediments from the north sea possible origins for these compounds are discussed

a new species of chasmosaurus dinosauria ceratopsia from the dinosaur park formation of southern alberta chasmosaurus irvinensis sp nov is distinguished from other species of this genus by the possession of a broad snout absence of a brow horn the position of which is occupied by a pit or rugosities suggestive of bone resorption broadly rounded and open jugal notch subrectangular squamosal straight posterior parietal bar bearing 10 epoccipitals eight of which are flattened strongly curved anterodorsally and nearly indistinguishably coossified to their neighbours and small transversely oriented parietal fenestrae restricted to the posterior portion of the frill this species restricted to the upper part of the dinosaur park formation is significantly younger than the other recognized canadian chasmosaurus species c belli and c russelli phylogenetic analysis shows that c irvinensis is most closely related to the other canadian chasmosaurus species and more distantly related to chasmosaurus mariscalensis from texas

free radical transformations in the irati oil shale due to diabase intrusion abstract electron spin resonance esr spectroscopy was used to evaluate the effect of a diabase intrusion on the production and decomposition of free radicals in the irati oil shale parana basin brazil free radical concentration measurements on the stratigraphic column ceri 2 indicated that the ratio between the extent of thermal alteration on sedimentary organic matter and the intrusive thickness was 1 14 kinetics of free radical transformation obtained from laboratory pyrolysis of irati oil shale can be described by first order production and decomposition reactions of distinct species although these species present different kinetic parameters they are not resolved and lie inside the envelope of the single line esr spectrum the activation energies for parallel first order production reactions of two main species of free radicals in the temperature range of 360 420 c were found to be 54 2 kcal mol 1 and 36 9 kcal mol 1

accumulation rates of recent sediments in puget sound washington abstract sixteen profiles of unsupported 210pb activity from long cores along the axis of the main basin of puget sound show that bottom sediments are accumulating at rates of 0 26 0 03 to 1 20 0 16 g cm 2 yr 1 these rates and seven others published earlier suggest that highest accumulation occurs nearly midway along the length of this tidal current dominated basin bioturbated surface layers of cores are as deep as 40 cm but biologic mixing rates are poorly determined individual 210pb accumulation rates along the axis of the main basin range from approximately one to five times greater than the predicted areal average accumulation rate based on estimates of recent sediment input from adjoining rivers and shorelines

patterns of late paleozoic glacial sedimentation on the southeast side of the parana basin brazil abstract during the late paleozoic glaciation glaciers moved from southern africa over a platform composed of crystalline and sedimentary rocks into the subsiding parana basin of southeastern brazil in each successive glacial advance the platform was eroded and is marked by crescentic gouges striae roches moutonnees grooves and glacially modified valleys the glacial sediments which are found on the platform in southeastern brazil and margins of the parana basin were deposited from grounded ice and are termed terrestrial these sediments which are best exposed in the northern part of the study area are composed of supraglacial deposits such as layers of diamictite flow tillite interbedded with sandstones and minor amounts of lodgement tillite the supraglacial deposits are frequently faulted and the sandstones show pull apart structures and abnormal dips these features and others suggest that ice retreat in the terrestrial environment was primarily by down wasting the glaciogenic sediments found within the subsiding parana basin are termed basinal even though it is not certain that they were all deposited in a subaquatic environment they are composed primarily of sandstones siltstones shales and mudstones interbedded with massive and laminated diamictites it is suggested that the massive diamictite was deposited from the base of the advancing glaciers by basal melting during ice retreat from water filled parts of the basin unstable masses of glaciogenic debris flowed down slope resulting in layered debris flows and in some instances chaotic debris flows which may have been triggered by subaquatic slupms and slides as the ice continued to retreat to the margin of the basin a complex of subaquatic outwash including deltaic sands was deposited minor varvites were deposited in shallow restricted embayments in the shoreline which were flooded with fresh glacial meltwaters deposits of retreat including the varvites interfinger with marine fossiliferous sediments which suggests that the water level in the basin was rising during deglaciation it is not known how may times glaciers advanced into the parana basin but recent studies show that there were at least nine glaciations in the northern part of this study area covering a time span of from 10 to 35 million years

neodymium isotopic composition of intermediate and deep waters in the glacial southwest pacific abstract neodymium nd isotopes tracers of deep water mass source and mixing were measured on sedimentary planktic foraminifera with authigenic coatings from a depth transect of cores 1400 4800 m from chatham rise in the southwest pacific over the past 30 ka we observe deglacial variations in the nd isotopic composition which showed an average glacial composition of e nd 5 0 1 0 3 n 4 for cores sites below 3200 mbsl no significant deglacial variation was observed in the nd isotopic composition of intermediate depth waters 1400 mbsl in contrast with benthic foraminifera c 13 data the deglacial e nd shift of cdw in the southwest pacific is consistent with changes observed in the deep south atlantic and equatorial indian ocean but e nd values are offset by 1 e nd unit to more radiogenic values throughout the deglacial records likely due to admixture of a nd isotope signal which was modified in the southern ocean or pacific perhaps by boundary exchange however this modification did not overprint the deglacial nd isotope change the consistent deglacial evolution of e nd in the south atlantic equatorial indian and southwest pacific cdw is evidence for the connection of cdw during the glacial and propagation of diminished north atlantic deep water export to the glacial southern ocean in contrast spatial heterogeneities in the benthic foraminifera c 13 of cdw have been observed in the atlantic indian and pacific basins of the deep glacial southern ocean the nd isotope data implies a well connected deep southern ocean which transported waters from the atlantic to the indian and pacific oceans during the glacial this suggests that basin scale variability in the glacial c 13 composition of cdw was unrelated to circulation changes

the behavior of particle reactive tracers in a high turbidity environment 234th and 210pb on the amazon continental shelf excess 234th and 210pb seabed inventories were measured in cores collected from the amazon continental shelf to examine particle scavenging and seabed dynamics typical excess 210pb inventories range from 100 to 300 dpm cm 2 and the total excess 210pb inventory for the amazon shelf was determined to be 2 7 1017 dpm the 210pb measurements indicate that particle reactive species are scavenged not only from the amazon river but also from the lateral advection of offshore water in order to sustain the 210pb inventories the volume of water supplied by the lateral advection from offshore must be approximately five to ten times the water discharge of the amazon river this lateral advection supplies about 67 of the total excess 210pb to the amazon continental shelf with relatively small contributions from riverine input 31 atmospheric fallout 2 3 and in situ production 0 1 the 234th inventories were measured on four cruises which occurred during periods of differing river discharge wind stress and flow rates of the north brazil current the 234th excess seabed inventories show large spatial and seasonal variability with a range from 0 to 22 dpm cm 2 ratios of predicted 234th inventories over observed 234th inventories indicate that a large portion of the inventories on the inner and mid shelf occur in the fluid mud layer or the suspended sediments the 234th excess seabed inventories are controlled by resuspension cycling the inventories between the water column and the seabed 210pb and 234th excess seabed inventories are compared directly using corrections for the different time scales and offshore concentrations this approach indicates that for most of the shelf the inventories of the shorter term tracer 234th are less than predicted by the inventories of the longer term tracer 210pb there are two explanations for this trend the first is that a larger portion of the 234th inventory occurs in the fluid muds or the water column relative to 210pb the second is that the supply of offshore water scavenging efficiency and or deposition have been lower over the two year study period relative to the last one hundred years

sea surface temperature variability in the subpolar atlantic over the last two millennia 1 a decadal resolution time series of sea surface temperature sst spanning the last two millennia is reconstructed by combining a proxy record from a new sediment sequence with previously published data from core md99 2275 north of iceland the alkenone based sst reconstruction is validated with historic observational data and compared to a new similar temporal resolution reconstruction obtained from sediment core rapid21 3k in the subpolar north atlantic the two sst paleorecords show consistent multidecadal scale coolings throughout the interval and similar expressions during the contrasted climatic periods colloquially known as the medieval climatic anomaly mca and little ice age lia in order to further understand the temporal and spatial sst variations and investigate the influence of natural forcings on the observed sst changes during the last millennium we compare our time series to simulations using the institut pierre simon laplace ipslcm4 v2 climate model this comparison highlights the potential importance of volcanism as a natural forcing driving coherent abrupt cooling events captured in the subpolar north atlantic records

geochemical mass balance for lithium boron and strontium in the gulf of papua papua new guinea project tropics a mass balance has been calculated for the elements li b and sr in the gulf of papua from sampling undertaken during 1993 to 1999 parameters measured included fly kikori and purari river inputs of dissolved and particulate phases removal flux to sediment traps at the base of the continental shelf slope and century scale accumulation rates in shelf and slope sediments derived from excess 210pb profiles in sediment cores about 91 of river input li was in particulate form and there was conservative behavior of dissolved li in the salinity gradient of the estuaries li accumulation rate in inner shelf sediments was slightly less than river inputs suggesting that more than 90 of li river inputs were trapped in rapid aluminosilicate mud accumulation zones of the inner shelf 50 m depth li removal rate to sediment traps at the base of the slope at 1000 m water depth was an order of magnitude smaller than the inner shelf sedimentation export of li to deep water coral sea was estimated to be 1 2 108 mol yr 1 and this amount is equivalent to the riverine dissolved li annual supply rate about 66 of river input of b was in the particulate phase and low dissolved b concentrations in freshwater were conservatively mixed with higher concentrations of b in seawater across the salinity gradient removal of b to inner shelf sediments was about 83 of the total river input indicating a small export of b 1 2 108 mol yr 1 to the coral sea about half of the dissolved b input from rivers is sorbed to particles and trapped in inner shelf sediments only 24 of river input of sr was in particulate form and low freshwater concentrations of dissolved sr were conservatively mixed with higher concentrations of sr in seawater across the salinity gradient only 20 of total river inputs of sr were buried in shelf sediments and there was a large export 7 3 108 mol yr 1 of sr off the shelf to the coral sea a sediment core from a rapidly accumulating mud deposition zone of the inner shelf shows twofold sympathetic variations in li b and sr ca supply rates over 200 to 1000 yr time intervals

paleotemperatures and paleofluids recorded in fluid inclusions from calcite veins from the northern flank of the ponta grossa dyke swarm implications for hydrocarbon generation and migration in the parana basin abstract the parana basin southern brazil has an atypical thermal and fluid history due to the occurrence of an episodic continental flood volcanism during the early cretaceous so far there are few data about the influence of this volcanic event on the paleotemperatures and paleofluids of the parana basin sedimentary rocks the teresina formation in the northern flank of the ponta grossa dyke swarm hosts high concentration of subsurface igneous rock bodies sills and dykes besides its covering by a hundreds meter thick volcanic rock cap in this study we used fluid inclusion analysis performed in horizontal and vertical calcite veins from the teresina formation and from a late cretaceous basic dyke to estimate paleotemperatures and to characterize the composition of diagenetic paleofluids homogenization temperatures of requilibrated fluid inclusions show that the teresina formation reached temperatures above 200 c horizontal parallel bedding calcite veins from the teresina formation record low to high salinity 2 26 wt nacl eq aqueous paleofluids the prevalence of high salinity fluid inclusions associated with light hydrocarbon fluid inclusions indicates deep buried fluids fluid inclusions in vertical calcite vein from basic dyke comprise only low salinity aqueous fluids 0 3 wt eq nacl interpreted as dominated by meteoric water the recorded paleotemperatures are attributed to the heating by the parana volcanic event during the early cretaceous with the thermal effect of the volcanic rock cap surpassing the effect of nearby sills and dykes estimated paleotemperatures higher than 200 c would allow the generation of light liquid and gaseous hydrocarbons overpressured compartments in the teresina formation allowed the expulsion of buried pore fluids high salinity aqueous fluids and hydrocarbons to fracture systems where they mixed with meteoric water the input of meteoric water through fracture systems connected with the surface favored hydrocarbons degradation in the early stages of source rock maturation during the early cretaceous

an examination of froude supercritical flows and cyclic steps on a subaqueous lacustrine delta lake chelan washington u s a density driven submarine flows including turbidity currents play an important role in the transfer of sediment into deep water these bottom hugging flows often produce flow transverse bedforms along their path a sedimentological and geophysical survey of the stehekin river delta in lake chelan washington reveals a downslope elongate field of bedforms on the delta foreset associated with hyperpycnal discharges of the stehekin river an analysis of the bedform morphologies delta geometry and density contrast between lake and river water suggests that these hyperpycnal flows are froude supercritical the bedforms are likely cyclic steps flow transverse bedforms that are bounded by stable hydraulic jumps between alternating subcritical and supercritical flow regimes the ability to examine the three dimensional bed configuration produced by natural density driven flows adds valuable information to the body of experimental work focused on the behavior of cyclic steps in flumes

high resolution dinoflagellate cyst record of environmental change in effingham inlet british columbia canada over the last millennium abstract we present a high resolution sedimentary record of dinoflagellate cysts spanning the last 900 years recovered from effingham inlet a glacial fjord on the west coast of vancouver island canada the combination of seasonal coastal upwelling supporting high levels of marine primary productivity in surface waters together with restricted bottom water circulation in the silled fjord fosters the preservation of laminated sediments in the inner basin of effingham inlet geochemical data are used to assess the sedimentary facies of the core which is composed primarily of laminated units 50 2 occasionally interrupted by seismites 39 5 and homogenous units 10 2 the chronology of the 2 m long core is based on varve counting and fifteen 14c dates and is anchored by a seismite previously dated at ad 1946 the dinoflagellate cyst assemblages are diverse total of 47 taxa abundant average concentrations of 102 900 cyst g 1 of dry sediment and characterized by a proportionally equal contribution of autotrophic and heterotrophic cyst taxa in most samples overall cyst assemblages are characterized by operculodinium centrocarpum 36 2 accompanied by brigantedinium spp 18 0 and dubridinium spp 6 6 multivariate analyses are used to extract the dominant patterns of variability in autotrophic and heterotrophic dinoflagellate cyst assemblages separately and help in identifying the temperature and primary productivity gradients encoded in the cyst sedimentary record in this particular estuary specific intervals identified in the dinoflagellate cyst record are interpreted to represent the local expression of the medieval climate anomaly from the base of the record ad 1090 to 1230 the little ice age ad 1230 to late 19th century and warming in the second half of the 20th century the timing of these intervals are consistent with the regional paleoclimate and help constrain past climatic and oceanographic variability on the west coast of vancouver island the origin of homogenous units in the sedimentary record of effingham inlet and paleoseismicity in the region are also discussed

authigenic ferrimagnetic iron sulfide preservation due to nonsteady state diagenesis a perspective from perseverance drift northwestern weddell sea we document magnetic mineral diagenesis with high resolution magnetic susceptibility hysteresis isothermal remanent magnetization and other rock magnetic measurements through a shallow sulfate m