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

oceanography bathymetry and syndepositional tectonics of a precambrian intracratonic basin integrating sediments storms earthquakes and tsunamis in the belt supergroup helena formation ca 1 45 ga western north america abstract the carbonate dominated helena formation of the mesoproterozoic belt supergroup of western north america provides an instructive example of how a range of regional depositional and environmental characteristics of an ancient sea can be deduced on the basis of micron to metre scale features particularly revealing is the window opened by the presence of abundant molar tooth structure onto the paleoceanography paleobathymetry paleoclimate and tectonic regime of this intracratonic precambrian basin the facies hosting molar tooth structure is composed dominantly of lime mud with substantial subangular quartz and feldspar silt and clay derived from the western and southwestern side of the basin these are low energy tempestites deposited on a remarkably flat sea bottom at the limit of storm wave base at about 50 m sporadic domical stromatolite patch reefs confirm that the sea bottom was normally within the photic zone the ubiquity of molar tooth structure suggests frequent near field seismic activity during subsidence which generated ground motion sufficient to liquefy granular lime mud and terrigenous silt sporadic tsunamis from major submarine faults far to the west pounded the shallow water platform to the east tsunami off surge swept ooids and rounded coarse grained feldspathic quartz sand westward into deeper water and created strongly erosive currents that left gutter casts composed of lags of preferentially cemented molar tooth structure in otherwise relatively low energy facies mineralogical and geochemical evidence confirms that the belt basin was marine organic matter was essentially fully oxidized in the water column original high mg composition and cementation of lime mud in molar tooth structure indicate that calcite precipitated above the thermocline in supersaturated seawater under tropical conditions scattered bimineralic ooids in allochthonous grainstones indicate that shoals on the platform to the east were intermittently above a shallow aragonite compensation depth in warm water rare vestiges of halite and gypsum demonstrate occasional temporary salinity stratification for periods of up to a few years unaltered feldspar and mica grains point to a generally arid climate but the large volume of clay is suggestive of protracted weathering and transport

a new ceratopsid dinosaur ornithischia from the uppermost horseshoe canyon formation upper maastrichtian alberta canada a skeleton of a new ceratopsid dinosaur eotriceratops xerinsularis gen et sp nov is described in this paper it is the first associated vertebrate skeleton found within the upper 20 m of the horseshoe canyon formation eotriceratops xerinsularis is a large chasmosaurine that differs from other chasmosaurines in a unique set of features in the premaxilla nasal horn core squamosal frill and epijugal the most striking of those features includes an extremely tall non recessed narial process of the premaxilla the presence of greatly elongate spindle shaped epoccipitals on the squamosal frill a deep well demarcated fossa on the anteroventral surface of the squamosal frill a sharply conical epijugal with a pronounced proximoposterior process and separate fossa like facets for the jugal and quadratojugal and the presence of an obliquely extending vascular trace meeting a transverse vascular trace ventrally on the anterior surface of the nasal horn core our phylogenetic analysis suggests that e x

evidence for the formation of illite from smectite during burial metamorphism in the belt supergroup clark fork idaho abstract mineralogic and chemical data have been obtained for 26 argillite samples collected from an 8500 meter section of the precambrian belt supergroup clark fork idaho minerals present are quartz feldspar illite and calcite calcite and or dolomite illite quartz and chlorite quartz ratios decrease up section supporting the conclusion of boyce 1973 that the belt section represents an ancient prograding delta the ratio of k feldspar to total feldspar decreases from 20 80 percent in the upper two thirds of the section to 0 10 percent in the lower one third the mechanism proposed for the decrease in k spar down section is the conversion of k poor smectite into k rich 1md illite a later higher temperature reaction converted much of the 1md illite into 2m illite muscovite e suggest that a low k spar plagioclase ratio in an illite containing shale suite indicates that the illite formed from smectite during metamorphism rather than from the direct weathering of some high temperature phase such as feldspar most continental volcanic material is produced during orogenic episodes most smectite forms from volcanic material and smectites will be converted into illites if enough time has elapsed for them to have been involved in one or more geosynclinal cycles therefore the proportion of smectite in sediments through time can be related to the timing of orogenic episodes this model works fairly well in north america where smectite maxima coincide with orogenic episodes becoming smaller with increasing antiquity of the orogeny

application of the sphalerite cosmobarometer to the enstatite chondrites sphalerite is a minor constituent of a number of enstatite chondrites the assemblage sphalerite troilite kamacite buffers the iron content of sphalerite so that it is a function of temperature and pressure only high iron contents in sphalerite in enstatite chondrites are consistent with equilibration at low pressures if nebular conditions are assumed and pressure is taken as zero it is then possible to calculate blocking temperatures for diffusion of iron t b and cooling rates for the meteorites studied the variable degree of equilibration of eh3 chondrites is correlated with calculated pressures assuming that the least equilibrated y69001 formed at zero pressure parent body radii calculated from these pressures are probably too large however inhomogeneities and minor elements in sphalerite as well as the assumptions made in the calculation may have had an adverse effect on the calculations the eh4 chondrite indarch appears to have cooled at an extremely rapid rate and has an unreasonably high t b inhomogeneities and minor element content may again have affected results the data for the el6 chondrites are consistent with relatively slow cooling ca 773 k whereupon rapid cooling occurred cooling rates at 773 k are too fast by a factor of 102 to 103 in comparison with metallographically determined rates

genesis of the taolin pb zn deposit in northeastern hunan province south china constraints from trace elements and oxygen sulfur lead isotopes of the hydrothermal minerals located in the northeastern hunan province of south china the taolin pb zn deposit is one of many metallic deposits structurally controlled by extensional faults in the central segment of the jiangnan orogen the deposit occurs in a tectonic breccia zone between the mufushan pluton and the neoproterozoic lengjiaxi group field and microscopic observations reveal that the hydrothermal ore forming processes at taolin can be divided into five stages from early to late 1 coarse grained quartz 2 quartz fluorite chlorite claybank sphalerite sp1 galena chalcopyrite 3 quartz barite pale yellow sphalerite sp2 galena chalcopyrite 4 quartz chalcopyrite and 5 fine grained quartz in which the stages 2 and 3 are regarded as the main pb zn forming events la icp ms analyses show that sp1 has higher contents of fe mn co in and sn but lower contents of ge and sb relative to the sp2 trace element concentrations of the sphalerite suggest a medium low temperature hydrothermal event dominated in the taolin deposit and that the ore fluids gradually decreased in the estimated average temperature and became relatively oxidized from stages 2 to 3 the 18o values of ore fluids calculated from in situ analysis on the stages 2 and 3 quartz suggest the ore fluids are from a mixture of magmatic and meteoric waters the 34s values of sulfides sulfates from stages 2 and 3 mineralization indicate a dominating magmatic affinity for sulfur further lead isotope compositions for the stages 2 and 3 sulfides are similar to those of the mufushan pluton indicating that the ore metals may have been derived from the latter we thus propose that the taolin deposit precipitated from a medium low temperature magmatic hydrothermal system most likely related to the mufushan pluton

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

differential mobility of elements in burial diagenesis of siliciclastic rocks abstract mass balance calculations involving smectite rich siliciclastic mudstones sampled from boreholes show that significant k2o addition and cao loss correlate strongly with the progress of illitization of smectite and with the dissolution of calcite the calculations are based on the immobility of al2o3 and require a chemically homogeneous sediment at deposition such that the shallower samples represent protolith compositions of deeper samples constancy of ratios of tio2 al2o3 are used to 1 establish that both tio2 and al2o3 have similarly low differential mobilities and 2 identify stratigraphic sections available in the literature that are sufficiently homogeneous to allow the calcu ations our calculations show that most major oxide components are immobile at the 5 limit of resolution of the calculations exceptions are k2o which is almost universally added to mudstones and cao which is commonly removed from mudstones during diagenesis the addition of up to 50 k2o correlates with percent illite in mixed layer illite smectite indicating that illitization of smectite involves fixation of k2o from diagenetic fluids removal of 40 cao from some sections correlates with decreasing calcite mode and is attributed to dissolution of calcite together these reactions lead to a 10 15 loss of mineral volume a volume loss that must be added to porosity loss when modeling compaction illitization and carbonate dissolution may be linked because k fixation during illitization decreases the ph of the local fluid a reverse weathering reaction which enhances carbonate dissolution addition of up to 20 na2o in some rocks may be caused by albitization of plagioclase but na2o addition is not pervasive the apparent lack of mass transfer associated with dissolution of kaolinite and feldspars or precipitation of chlorite implies that these reactions are balanced by other reactions such that their oxide components in mudstones are conserved limited data from sandstone mudstone pairs are consistent with transfer of k2o from sandstones to mudstone via rising diagenetic fluids except for cao and the alkalis diagenesis of siliciclastic mudstones appears isochemical 5 relative for most major oxide components the much larger changes recorded in some reservoir sandstones are clearly exceptions and may not reflect changes occurring at the scale of kilometers

minor elements in layered sphalerite as a record of fluid origin mixing and crystallization in the navan zn pb ore deposit ireland this study tests the utility of the minor to trace element composition of sphalerite to discriminate between possible sources of ore forming fluids and to constrain processes involved in ore genesis of the world class irish type navan zn pb orebody ireland detailed petrography and electron microprobe microanalyses were performed on layered sphalerite previously analyzed for zn fe and s isotope compositions layered sphalerite displays a wide range of chemical composition at both sample and crystal scales the color style and scale of layering show variations with chemical composition but none of these correlations are consistent between samples however there are strong intersample correlations between chemical and s fe zn isotope compositions at the millimeter scale sphalerite precipitated from deep hydrothermal fluids with 34s enriched sulfide is enriched in cd sb cu and ag whereas fe and as are enriched in sphalerite precipitated from shallow bacteriogenic brines with isotopically light s significant chemical variations also occur at the micrometer scale in sphalerite regardless of its genetic affinity these variations are interpreted as being due to variations in temperature ph and sulfur activity following the arrival at the site of deposition of pulses of hydrothermal fluids at specific stages of sphalerite growth therefore the chemistry of sphalerite coupled with its texture appears to be a powerful tool to elucidate fluid typing and ore genesis the results support the hypothesis that layered sphalerite forms by rapid crystallization due to mixing of two fluids of contrasting physicochemical properties a process required for the formation of irish type and some other hydrothermal deposits including most notably mississippi valley type mvt deposits the existence of layered sphalerite coupled with its texture and chemical composition may therefore provide useful insight for the mineral exploration industry in ireland and elsewhere

porosity reduction in sandstone by quartz overgrowth a mathematical model for predicting porosity histories due to quartz overgrowth in quartz rich sandstone reservoirs has been developed the model neglects secondary dissolution porosity and other diagenetic processes such as compaction and precipitation of carbonate and clay minerals nevertheless the model is straightforward and easy to use to calculate porosity the calculated porosity corresponds to measured porosity of simple quartz cemented sandstones in 27 wells in north and south america the model is based on fluid flow through initially porous unlithified sands in which the fluid phase is saturated with si oh 4 and is always in equilibrium with quartz as the continuously circulating fluid migrates updip toward the basin edge it cools and quartz precipitates into the pore spaces causing a loss of porosity basinal fluid velocities may be calculated assuming 1 thermal convection and 2 hydrostatic pressure due to recharge at the edge of the basin porosity diagrams relating porosity to geothermal gradient burial rate and depth of burial are compared to thermal maturation models of source rocks fluid flow history and grain size distribution the rate of porosity reduction depends on the following variables in decreasing order of significance buria rate age initial porosity basin size dip angle fluid dynamics initial permeability and geothermal gradient

syneresis cracks subaqueous shrinkage in argillaceous sediments caused by earthquake induced dewatering abstract syneresis cracks often confused with subaerial desiccation phenomena are traditionally ascribed to subaqueous shrinkage whereby salinity changes caused deflocculation of clay this and other previously proposed mechanisms fail to account for their occurrence in low energy typically non evaporitic facies stratigraphically sporadic distribution intrastratal formation under shallow burial depths variation in morphology degree of contraction generation of sedimentary dikelets as crack fills and deformation of dikelets and enclosing layers instead it is suggested that ground motion from strong synsedimentary earthquakes caused argillaceous sediments to dewater interbedded sands and silts to be almost simultaneously liquefied and injected into the resulting fissures and then these dikelets to be distorted comparative rarity of syneresis cracks in phanerozoic versus precambrian marine strata is considered to be primarily an evolutionary consequence of theological changes caused by increased organic binding of clay flocs in the water column greater input of organic matter into the sediment and the diversification of sediment dwelling bacteria and meiofauna in phanerozoic deposits

sphalerites in eh chondrites i textural relations compositions diffusion profiles and pressure temperature histories abstract sphalerite bearing assemblages in the unequilibrated eh chondrites qingzhen yamato 691 and indarch were studied to understand their pressure and temperature histories sphalerite in qingzhen and in yamato 691 are zoned with descending fes concentration to troilite compositions of sphalerite cores in qingzhen and yamato 691 are similar 47 03 49 6 mol fes in qingzhen versus 47 4 49 7 mol fes in yamato 691 the fes contents of the sphalerite rims to troilite are comparable 45 98 mol in qingzhen 42 3 mol in yamato 691 exsolution lamellae of troilite were found in several sphalerite grains in qingzhen the fes content in these grains also decreases to a value as low as 45 4 mol fes near the contact to the lamellae secondary homogeneous sphalerite formed during a late metamorphic episode in yamato 691 800 m y ago is characterized by low fes content 43 2 42 3 mol fes the descending concentration profiles in sphalerites in qingzhen and yamato 691 were produced by re equilibration of the sphalerite with the neighbouring troilite at high pressures during late metamorphic episodes however the compositions of sphalerite cores may reflect primordial compositions after sphalerite condensation but before its burial in the parent asteroid we obtain closure temperatures between 639 k and 728 k and 650 k and 732 k for sphalerites in qingzhen and yamato 691 respectively from compositions of sphalerite rims we estimate that the re equilibration took place at 0 18 kbar in qingzhen and at 0 77 0 95 kbar in yamato 691 qingzhen and yamato 691 were metamorphosed at different times and much later after accretion 1 4 b y and 800 m y respectively sphalerite in indarch displays complex textures indicative of multiple metamorphic events its fes content varies between 53 0 and 56 0 mol the grains contain open pores and are subdivided by platelets arranged parallel to 111 planes of the original sphalerite this is strongly suggestive of sphalerite wurtzite inversion and release of a volatile species 83 in a violent event

variations in mixed layer illite smectite diagenesis in the rift and post rift sediments of the jeanne d arc basin grand banks offshore newfoundland canada mixed layer illite smectite i s clays were analyzed from 22 deep exploration wells from the jeanne d arc basin on the grand banks offshore newfoundland the host of large commercial hydrocarbon accumulations discovered in the last two and a half decades the fine fraction of the clays 0 1 m consists mainly of mixed layer i s with minor amounts of kaolinite illite and chlorite smectite and or smectite rich i s clays were supplied to the jeanne d arc basin from upper jurassic to tertiary times smectite rich i s clays occur only in shallow samples irrespective of geologic age the proportion of illite in i s mixed layers as well as the degree of ordering increase with depth and temperature indicating that smectite rich i s clays have been progressively illitized in both rift and post rift sediments of the jeanne d arc basin during burial the transition from random to r1 ordered i s occurs between subsurface depths of 1940 and 3720 m and crosses major stratigraphic boundaries the transition fr

redescription of ualvp 40 an unusual specimen of chasmosaurus lambe 1914 ceratopsidae chasmosaurinae bearing long postorbital horns and its implications for ontogeny and alpha taxonomy of the genus ualvp 40 an articulated and reasonably complete skull of a small chasmosaurine dinosaur collected in 1920 by george f sternberg from the lower unit of the dinosaur park formation dinosaur provin

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

oxygen isotope map of the giant metamorphic hydrothermal system around the northern part of the idaho batholith u s a abstract determinations of 18o values from 100 outcrops of belt supergroup wallace fm metasedimentary rocks in the idaho panhandle reveal a regular regional pattern that was produced by pervasive fluid infiltration and isotopic exchange low grade argillites at large distances 60 km from the idaho batholith have high 18o values 15 compatible with their probable primary values pelitic rocks with anomalously low 18o values of 8 7 to 12 7 occur in the following zones 1 in a 5000 km2 zone of schist and gneiss peripheral to the idaho batholith generally coincident with high grade sillimanite bearing assemblages 2 in high grade metasedimentary roof pendants within the idaho batholith 3 peripheral to small cretaceous stocks and 4 within and near the scapolite bearing zone south west of st regis on 18o 18o plots data from coexisting minerals define trends with unit slopes indicating that the reductions in 18o occurred under high grade metamorphic conditions this metamorphism culminated in the emplacement of the idaho batholith probably as a consequence of profound crustal thickening associated with the cretaceous accretion of the wallowa seven devils arc terranes with north america the huge low 18o region is bounded by a steep 18o gradient 0 1 0 5 km that occurs in low grade rocks along and near the lewis and clark line well below the biotite isograd this boundary zone may be analogous to but is not nearly as sharp as those of meteoric hydrothermal systems in many regions the important ore deposits of the coeur d alene district are located in this peripheral zone suggesting that the metamorphic hydrothermal system may have been intimately involved in their formation in addition the metamorphic hydrotermal system in idaho is larger deeper and higher in temperature than typical meteoric hydrothermal systems and it involved fluids with much higher 18o values that were probably dominantly derived from formation waters accordingly this system produced rocks with 18o values similar to those of the idaho batholith and mineral assemblages that approach isotopic equilibrium under high temperature conditions

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

the influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern united states this paper reports systematic changes in mudrock composition through time on a single con tinental cmstal block the changes reflect both sediment recycling processes and changes through time in the composition of crystalline material being added to the sedimentary system and are related to tectonic evolution as the block matures from a series of accreted arc terranes to a stable craton the major and trace element distributions reflect different aspects of the provenance of the mudrocks in this study major elements record sediment recycling processes as well as changing proportions of sedi mentary and first cycle source rocks with the exceptions of kzo which tends to increase and sioz and a o3 which show no trend most major oxides tend to decline in relative abundance in younger mud rocks patterns shown by the index of compositional variability fe03 kro naao cao mgo mno tiojialro and by k20 a1203 indicate that the major oxide trends are due to decreasing proportions of nonclay silicate minerals and a concomitant increase in the proportion of clay minerals probably due to decreasing input of first cycle detritus coupled with recycling of sedimentary material excursions from progressive trends marked by increases in mgo k20 and cao reflect episodes of large scale input of nonclay first cycle minerals from crystalline source rocks due to large scale basement uplift the chemistry of low solubility trace elements in contrast is not sensitive to recycling effects and reflects the composition of first cycle input incompatible elements are progressively enriched relative to compatible elements in younger mudrocks and values for chondrite normalised rare earth elements also increase in addition the eu anomaly becomes systematically more negative in younger samples these trends cmnot be explained by diagenetic or weathering processes and therefore indicate that the proportion of fnc tionated granitic first cycle detritus being added to the sedimentary system becomes greater with time these results confirm the importance of tectonic setting in controlling mudrock chemistry and also demonstrate that there is a dynamic relationship between the tectonic evolution of a continental block and the composition of its sedimentary mantle

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

sedimentation earthquakes and tsunamis in a shallow muddy epeiric sea grinnell formation belt supergroup ca 1 45 ga western north america

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

experimental calibration of the sphalerite cosmobarometer abstract the pressure and temperature dependence of the composition of sphalerite in equilibrium with troilite metallic iron has been determined experimentally at 2 5 and 5 0 kbar between 400 and 800 c using both the aqueous and anhydrous alkali halide flux recrystallization techniques the measured pressure effect is larger than that calculated by us and by schwarcz et al 1975a and is described by the equation t in kelvins p kbar 3 576 0 0551 t 0 0296 t log mole fes assuming temperatures of final equilibration between sphalerite and troilite of 350 c for iron meteorites and 600 c for enstatite chondrites published analyses of sphalerites provide estimates of pressures of formation and possible radii of parent objects of meteorites as follows ia irons landes sardis gladstone bogou odessa toluca 0 0 to 3 5 kbar 0 to 442 km e6 enstatite chondrites yilmia pillistfer 0 2 to 0 7 kbar 0 to 198 km

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

the thermometry of enstatite chondrites a brief review and update due to the discoveries in antarctica the number of known enstatite chondrites has doubled in the last few years and many rare or previously unknown types have been collected most notably many el3 and eh3 chondrites we have applied the five major enstatite chondrite thermometers to the new and previously known enstatite chondrites the thermometers being 1 kamacite quartz enstatite oldhamite troilite kqeot 2 oldhamite 3 alabandite niningerite 4 sphalerite and 5 phosphide metal measured temperatures based on the kqeot and oldhamite systems are 800 c 1000 c with the type 3 enstatite chondrites having values similar to those of type 4 6 it seems likely that these temperatures relate to events prior to parent body metamorphism such as nebula condensation or chondrule formation and were not significantly reset by later events measured temperatures for alabandite niningerite metal phosphide and sphalerite in eh chondrites increase from 300 c 400 c to 600 c 800 c with petrographic indications of increasing metamorphism in contrast measured temperatures for all el chondrites including the most heavily metamorphosed are generally 400 c apparently el chondrites cooled more slowly than the eh chondrites regardless of metamorphism experienced measured temperatures for the alabandite niningerite metal phosphide and sphalerite are actually closure temperatures for the last thermal event suffered by the meteorite and the fast cooling rates indicated are most consistent with processes occurring in thick regoliths

a comparative study of opaque phases in qingzhen eh3 and macalpine hills 88136 el3 representatives of eh and el parent bodies opaque minerals in the qingzhen eh3 and macalpine hills mac 88136 el3 enstatite chondrites were studied and compared with other eh and el chondrites all opaque minerals usually occur in multi sulfide metal clasts and nodules in the matrix between chondrules el goresy et al 1988 the higher abundance of opaque minerals the occurrence of niningerite and various alkali sulfides e g caswellsilverite phases a and b djerfisherite are diagnostic criteria for eh chondrites while alabandite is characteristic for el chondrites in addition eh chondrites are characterized by enrichments of si in both kamacite and perryite and alkali elements in sphalerite and chalcopyrite the mn contents of daubreelite and sphalerite are lower in eh than in el chondrites these are consistent with lower oxygen fugacity and higher h2s fugacity of eh than el chondrites in contrast the discovery of sphalerite and zn rich daubreelite in mac 88136 indicates that their absence in el6 chondrites is probably related to thermal metamorphism in the parent body schreibersite microspherules are commonly enclosed in most sulfides in qingzhen but are absent in mac 88136 they were once molten and probably predated all sulfide host phases the petrographic setting and chemical compositions of the sulfide hosts of the schreibersite microspherules in eh3 chondrites are consistent with formation by condensation the earliest sulfide condensates oldhamite and niningerite occupy the interiors of the clasts and nodules whereas the rims consist of troilite and djerfisherite in addition in qingzhen some other troilite djerfisherite and sphalerite assemblages coexist with perryite they were produced by sulfurization of metallic fe ni in the nebula in mac 88136 sulfurization of si bearing fe ni metal is less pronounced and it produced troilite schreibersite and less abundant perryite two kinds of normal zoning and a reverse zoning trends of niningerite and both normal and reverse zoning of sphalerite were found in clasts and nodules in qingzhen the coexistence of normal and reverse zoning profiles in niningerite grains in the same meteorite strongly suggests that they formed before accretion in the parent body because an asteroidal metamorphic or an impact event in the parent body would have erased these contrasting profiles and destroyed the textural settings in contrast alabandite in mac 88136 shows only normal zoning with the fes content decreasing to 9 3 mol toward troilite indicating very slow cooling at low temperature

trace and minor element variations and sulfur isotopes in crystalline and colloform zns incorporation mechanisms and implications for their genesis abstract various models have been proposed to explain the formation mechanism of colloform sphalerite but the origin is still under debate in order to decipher influences on trace element incorporation and sulfur isotope composition crystalline and colloform sphalerite from the carbonate hosted mississippi valley type mvt deposit near wiesloch sw germany were investigated and compared to sphalerite samples from 52 hydrothermal vein type deposits in the schwarzwald ore district sw germany to study the influence of different host rocks formation mechanisms and fluid origin on trace element incorporation trace and minor element incorporation in sphalerite shows some correlation to their host rock and or origin of fluid gangue paragenetic minerals and precipitation mechanisms e g diagenetic processes fluid cooling or fluid mixing furthermore crystalline sphalerite is generally enriched in elements like cd cu sb and ag compared to colloform sphalerite that mainly incorporates elements like as pb and tl in addition sulfur isotopes are characterized by positive values for crystalline and strongly negative values for colloform sphalerite the combination of trace element contents typical minerals associated with colloform sphalerite from wiesloch sulfur isotopes and thermodynamic considerations helped to evaluate the involvement of sulfate reducing bacteria in water filled karst cavities sulfate reducing bacteria cause a sulfide rich environment that leads in case of a metal rich fluid supply to a sudden oversaturation of the fluid with respect to galena sphalerite and pyrite this however exactly coincides with the observed crystallization sequence of samples involving colloform sphalerite from the wiesloch mvt deposit

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

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

near infrared spectra of white mica in the belt supergroup and implications for metamorphism the wavelength of the white mica illite and muscovite al oh absorption band near 2200 nm in 1036 samples from the belt supergroup and associated metasedimentary rocks was determined with a portable visible and near infrared reflectance spectrometer the al oh wavelength decreases from 2225 nm in sub biotite zone samples to 2194 nm in sillimanite zone samples this decrease corresponds with an increase in total al content of white mica from 2 0 to 2 8 atoms per 11 o atoms these observations indicate that 1 the frequency of the al oh vibration is controlled by the aluminoceladonite exchange reaction iv si vi mg fe 2 iv al vi al and 2 the reaction proceeds toward more al rich composition with increasing metamorphic grade in these circumstances al oh wavelength provides an indirect monitor of compositional variation and metamorphic grade metamorphic grade in most of the study area is in the biotite zone or lower yet al oh wavelengths in low grade rocks define systematic patterns that correlate with depth of burial and later structural displacements in higher grade areas wavelengths generally decrease from the garnet isograd through the sillimanite zone however anomalies occur locally and it is not clear whether these result from differences in bulk composition and mineral assemblage or whether they point to actual metamorphic or structural discontinuities these findings indicate that reflectance spectroscopy can yield valuable information on metamorphic intensity in rocks containing white mica particularly in low grade sequences where conventional indicators of metamorphic grade are lacking furthermore this information can be obtained with field portable spectrometers and the potential exists to obtain comparable results from airborne and spaceborne imaging spectrometers

sr and nd isotopic evidence for punctuated clay diagenesis texas gulf coast we report rb sr sm nd and mineralogical data for leached whole rock 1200 m independent of the duration of burial the exchangeable sr in the clay has remained an open system and has undergone isotopic exchange since that time minimum fluid rock ratios of 0 2 to 2 are modeled from sr isotopic data consistent with rock dominated open system diagenesis leachates and residues of the 0 1 zm fraction below the smectite illite transition appear to have achieved nd isotopic equilibrium during clay diagenesis and show no signs of subsequent exchange the clay residues have low 147sm 144nd 0 085 indicating that authigenic illite has a lower sm nd ratio than its bulk rock protolith conversely the coexisting exchangeable ree inventory has elevated sm nd as reflected by leachate 14vsm 144nd as high as 0 188 this sm nd fractionation in conjunction with the preserved isotopic equilibrium may be useful for dating diagenesis and associated fluid rock interaction in older rocks

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

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

composition and classification of paleozoic flysch mudrocks of eastern australia implications in provenance and tectonic setting interpretation abstract the mudrock suites of paleozoic flysch sequences of eastern australia can be characterised on the basis of the relative abundances of phyllosilicates and tectosilicates mainly feldspar and quartz a mudrock maturity index is defined as the ratio of total phyllosilicates to phyllosilicates feldspar quartz mudrocks are classified into tectic phyllo tectic and phyllic types on the basis of increasing maturity based on studied examples of eastern australia preliminary characteristics of mudrocks of various tectonic settings are identified oceanic island arc mudrocks are of the tectic type characterised by high feldspar and low phyllosilicate content they are derived from calc alkaline andesitic rocks of the magmatic arc mudrocks of the continental island arc and active continental margins andean type and strike slip basins are characterised by a higher phyllosilicate content and are mainly phyllo tectic in type passive margin mudrocks are of the phyllic type characterised by extremely high phyllosilicate and low feldspar contents suggesting their recycled nature mudrock maturity is accompanied by an increase in the k2o na2o ratio from oceanic island arc to continental island arc and active continental margin to passive margin type mudrocks

application of the sphalerite cosmobarometer to group iab iron meteorites abstract sphalerite compositions from ten members of iron meteorite group ia and one member of group ib were determined and pressures p 350 calculated assuming a blocking temperature for fe diffusion of 350 c although three meteorites ogallala and copiapo ia and woodbine ib yielded clearly outlying values the remaining eight members of group ia yielded pressures that were linearly correlated with 1 wt ni of the meteorite the equation of the regression line is 1 wt ni 0 163 0 0102p 350 pressures calculated range from zero for landes to 3 5 kbar for toluca the values for woodbine copiapo and ogallala appear to be due to the occurrence of sphalerite in copiapo type silicate inclusions sphalerite in these inclusions is believed to be only partially re equilibrated from compositions that were stable in winonaite parental materials