changes in optical properties chemistry and micropore and mesopore characteristics of bituminous coal at the contact with dikes in the illinois basin abstract changes in high volatile bituminous coal pennsylvanian near contacts with two volcanic intrusions in illinois were investigated with respect to optical properties coal chemistry and coal pore structure vitrinite reflectance ro increases from 0 62 to 5 03 within a distance of 5 5 m from the larger dike and from 0 63 to 3 71 within 3 3 m from the small dike elemental chemistry of the coal shows distinct reductions in hydrogen and nitrogen content close to the intrusions no trend was observed for total sulfur content but decreases in sulfate content towards the dikes indicate thermochemical sulfate reduction tsr contact metamorphism has a dramatic effect on coal porosity and microporosity in particular around the large dike the micropore volume after a slight initial increase progressively decreases from 0 0417 cm3 g in coal situated 4 7 m from the intrusive contact to 0 0126 cm3 g at the contact strongly decreasing mesopore and micropore volumes in the altered zone together with frequent cleat and fracture filling by calcite indicate deteriorating conditions for both coalbed gas sorption and gas transmissibility

biaxial vitrinite reflectance in coals of the elk valley coalfield southeastern british columbia canada ninety nine grab coal samples collected from ten different diamond drill cores from the jurassic cretaceous mist mountain formation in the elk valley coalfield in southeastern british columbia were analyzed petrographically for mean maximum vitrinite reflectance rmax mean random vitrinite reflectance rm and the lengths of the maximum intermediate and minimum axes of the reflectance indicating surface or ris of vitrinite rmaxrint andrmin coal rank in the coalfield ranges from high volatile a to low volatile bituminous values of rmax in the core samples range from 0 95 to 1 50 rmax rm rmax rint and rmin are all strongly intercorrelated r 0 89 in all combinations the vitrinite in all samples is biaxial in most cases biaxial negative as a consequence rmax is always less than rmax the relationship being rmax 1 044 rmax there is no relationship between degree of vitrinite reflectance anisotropy as represented by the ris shape and rank the results indicate that a secondary stress field not perpendicular to bedding existed during coalification

textural transformation of thermally treated anthracites abstract the organic matter of anthracites consists of turbostratic two dimensional crystalline order stacks of three to five aromatic layers called the basic structural units bsu the arrangement of bsu forms the texture of anthracites which corresponds to their chemical and physical properties including optical properties reflectance values thermal treatment leads to the changes in the arrangement of bsu the character of structural and textural transformation of anthracites during heating can be determined based on the changes of reflectance values of anthracites several anthracites of various ranks were thermally treated over the temperature range of 400 673 k 1000 c 1273 k in an inert atmosphere n2 at atmospheric pressure the reflectance indicating surfaces ris were reconstructed and reflectance indicatrix parameters were calculated according to the kilby method specially modified for the study of anthracites it was found that the relative increase of reflectance values rmax rmin was greater for the lower metamorphosed samples than for the higher ones however the higher rank of initial samples the greater their final reflectance values and the anisotropy of the texture attained at 1000 c it indicates that the texture of the higher metamorphosed anthracites meta anthracites is more flexible for rearrangement during heating than the texture of the lower metamorphosed anthracites moreover the difference in the changes of reflectance values versus temperature for the higher and for the lower rank anthracites suggests that meta anthracites have undergone stronger natural metamorphism equivalent to about 200 c in comparison with the other anthracites it could be said that the character of textural transformations of individual anthracites results from the degree of their metamorphism and in a consequence from the texture of parent sediments

timing of mammal like reptile extinctions across the permian triassic boundary in south africa the rate timing and pattern of change in different regions and paleoenvironments are critical for distinguishing among potential causes for the permian triassic p t extinction carbon isotopic stratigraphy can provide global chronostratigraphic control we report a large 13 c excursion at the p t boundary and no long term permian 13 c trends for samples from the interior of pangea stratigraphic gaps between available samples limit the resolution of our 13 c curve but the excursion is within a 15 m thick zone of overlap between permian and triassic taxa sedimentological and taphonomic observations demonstrate that this 15 m interval does not represent geologically instantaneous deposition together these data support a rapid and globally synchronous p t event but suggest that it occurred over a geologically resolvable interval of time

intra tooth isotope variations in late miocene bovid enamel from afghanistan paleobiological taphonomic and climatic implications abstract the rich mid turolian site of molayan afghanistan has yielded more than 100 mandibles from the bovid tragoportax afghanicus in this study we document different aspects of the paleobiology and paleoecology of this fossil bovid by examining patterns of inter and intra tooth carbon and oxygen isotopic analyses in m1 to m3 molars from five specimens accurate paleoecological and paleoclimatic inferences based on carbon and oxygen isotope analyses in fossil enamel are directly dependent upon the way in which teeth are sampled as well as taphonomic processes which are responsible for fossil accumulation because this sampling methodology provides a unique opportunity to detect seasonal changes in diet and environment during tooth formation it also offers the possibility of testing between catastrophic and progressive deposition at this site preservation of 13c and 18o values is shown to be good and permits inter individual comparisons of isotopic trends to be made timing of molar crown formation and enamel growth rate were deduced from the pattern of intra tooth carbon and oxygen isotope variation the pattern of 18o variation found in the first and second molars is similar in all the individuals which suggests that a single birth season occurred probably before the hot dry season large differences in average 18o values 2 5 are found within a single cohort and indicate that fossil accumulation was progressive rather than catastrophic the hypothesis that t afghanicus evolved in an open environment is supported by high 13c values in a c3 context increasing temperature and or aridity eastward along the greco irano afghan biogeographic province is strongly suggested by increasing 18o values between greece and afghanistan

fluid inclusion studies of the felbertal scheelite deposit fluid inclusion measurements on quartz scheelite beryl fluorite and calcite in the metamorphosed felbertal scheelite deposit display two main types of fluid inclusions 1 h2o co2 fluid inclusions are characterized by variable amounts of co2 up to 18 wt they show two or three phases at room temperature the bulk homogenization temperatures for the inclusions range between 269 c and 357 c the calculated salinities are between 2 2 and 7 8 wt nacl equivalent for the late co2 bearing fluid inclusions a methane component is evident from microthermometrical data tmclath 10 0 c combined with tmco2 56 6 c and from raman microprobe analyses 2 aqueous two phase fluid inclusions with salinities in the range between 0 and 11 wt nacl equivalent their homogenization temperatures are scattered between 100 c and 360 c

preservation of primary stable isotope signals in dinosaur remains and environmental gradients of the late cretaceous of montana and alberta abstract although the use of stable isotope data from vertebrate remains is becoming common for the cenozoic their application to mesozoic environments has been rare in part due to the perception that diagenesis has obfuscated all potential primary signal in this paper we illustrate how stable isotope data collected from dinosaur and other vertebrate remains can in fact be used to reconstruct paleoenvironmental conditions during the mesozoic carbon and oxygen isotope ratios were measured from tooth enamel of hadrosaur dinosaurs and from scales of freshwater fish that were collected from sites in the two medicine judith river and dinosaur park formations of montana and alberta these formations represent a coastal to upland gradient along the western margin of the late cretaceous inland seaway isotopic comparisons among skeletal components and among taxa are used as evidence that primary paleoenvironmental information as recorded by isotope data is preserved in tooth enamel and freshwater fish scales a comparison of carbon isotope ratios between hadrosaur tooth enamel and sedimentary organic matter indicates that these animals had a larger isotopic offset compared to bulk diet than modern mammals and that all hadrosaurian isotope data are consistent with the existence of c3 only ecosystems higher and more variable carbon and oxygen isotope ratios from animals occupying the coastal judith river region are interpreted to reflect a range of freshwater to brackish water conditions and plants that were undergoing water stress lower and less variable carbon and oxygen isotope ratios from the upland two medicine and intermediate dinosaur park areas are interpreted to reflect a gradual rainout of moisture from air masses moving inland and more uniform environmental conditions overall these results indicate that stable isotopes from dinosaur and other vertebrate remains have the potential to expand our understanding of terrestrial environments and ecosystems during the mesozoic

oxygen isotope variations in phosphate of biogenic apatites ii phosphorite rocks abstract phosphorites from sedimentary sequences ranging in age from archaean to recent were analysed for 18 o in both the po 4 18 o p and co 3 18 o c in the apatite lattice the oxygen isotope record is considerably better preserved in phosphates than in either carbonates or cherts the use of the longinelli and nuti 8 temperature equation yields temperatures for recent phosphorites that are in good agreement with those measured in the field the 18 o p values of ancient phosphorites decrease with increasing age these changes with time are not likely to be due to post depositional exchange changes in 18 o values of seawater and variations of temperature with time can account for the 18 o p time trend but the latter explanation is preferred in ancient phosphorites 18 o c in structurally bound carbonate in apatite is not a reliable geochemical indicator

a 16 ma record of paleodiet using carbon and oxygen isotopes in fossil teeth from pakistan abstract the siwalik sequence of northern pakistan contains a 16 ma record of paleosol carbonate and fossil teeth from which a record of paleovegetation can potentially be reconstructed and compared the carbon isotopic composition of paleosol carbonate and organic matter from siwalik strata reflects a major paleoecological change on the floodplains of major rivers beginning7 3 ma ago by 6 ma c 3 dominated plant communities probably composed of mostly trees and shrubs were displaced by nearly continuous c 4 grassland we find that the carbon isotopic ratios in herbivore tooth enamel reflect this dramatic ecologic shift carbonate in enamel older than 7 ma averages 11 in 13 c pdb consistent with a largely c 3 diet enamel from the plio pieistocene averages 1 9 in 13 c similar to the value displayed by modern c 4 grazers analysis of post burial carbonate cements and the concordance with isotopic evidence from paleosols argues strongly against major isotopic alteration of the enamel while coexisting bone may have been altered early in burial this study confirms that enamel apatite is useful for paleodietary reconstruction much further back in the geologic record than was previously thought

vitrinite reflectance anisotropy as a tectonic fabric element the anisotropy of the coal maceral vitrinite was analyzed in relation to the tectonic setting of a coal from the southern anthracite field in pennsylvania for the coal studied the maximum intermediate reflectance plane essentially paralleled the axial plane of the synclinorium n66 e strike 64 se dip

anthracitization of coals in the south wales coalfield abstract investigations by the institute of geological sciences on potential geothermal water sites in the coalfield of south wales have been reported they are of considerable interest and revive the controversy about the nature of the heat source responsible for the anthracitization of some coals in this classic area in the absence of exposed post carboniferous igneous rocks in the coalfield general opinion has favoured heat generation by friction along faults or disturbances we re examine the evidence in the light of more recent geophysical and geochemical investigations which suggest the possibility of igneous intrusions at a depth of about 3 5 km or shallower the likely age of such intrusions is also considered high seismic velocity basement rocks rise to only 2 5 km beneath the surface of the carboniferous in the northwestern anthracitized zone of the coalfield and we suggest that anthracitization in south wales is not the result of depth of burial nor of frictional heat but of proximity to a magmatic heat source associated with crystalline rocks of the basement

fossil isotope records of seasonal climate and ecology straight from the horse s mouth isotope analysis of a bulk fossil tooth gives a snapshot impression of paleoclimatic conditions a single point in time however hypsodont teeth grow over a period of a year or more so that stable carbon and oxygen isotope variations along their length are a tape recorder of short term seasonal variations from the distant past we have used a new in situ micro laser sampling method to determine submillimeter carbon and oxygen isotope variations in the enamel of individual fossil horse teeth to assess ancient annual meteoric water variations and feeding patterns the 18o values from a 6 8 ma fossil horse tooth astrohippus ansae from texas vary cyclically along the 6 cm length of the tooth with a smoothed amplitude of 4 similar to the monthly averaged amplitude measured in modern meteoric waters from the region the seasonal 18o values are 3 to 4 higher than those calculated from modern meteoric water data suggesting either a higher local meteoric water value in the miocene of texas or that the animal received a high proportion of its dietary water from plants or highly evaporated water a holocene horse tooth from the shores of glacial lake agassiz north dakota equus sp also has isotopic variations with the same 35 mm periodicity but a smoothed amplitude of only 2 this horse most likely had a buffered drinking supply the calculated 18o of the water in equilibrium with this tooth is the same as the modern measured annual average the variations within a single tooth can be as large as those generally observed in entire stratigraphic sections of fossil teeth analyzed by bulk methods the new method provides an important technique for evaluating fossil diagenesis conventional bulk analyses of teeth fragments may not be representative of the whole tooth thus explaining analytical scatter that has been previously attributed to diagenesis

reflectance anisotropy of upper carboniferous coals in the appalachian foreland basin pennsylvania u s a abstract patterns of vitrinite reflectance anisotropy in coal are represented by a three dimensional graphical form resembling an ellipsoid termed the vitrinite reflectance indicating surface vri naturally occurring vris from the northern appalachian basin pennsylvania range in shape from biaxial negative to biaxial positive depending on their coalification history and tectonic setting vri shapes are measured by estimating the magnitudes of the three principal reflectances rmax rint and rmin either on oriented blocks or non oriented grain mounts spatial orientations of the principal axes are determined by reflectance measurements on oriented polished cores the various vri shapes are portrayed on axial ratio diagrams i e plots of r max r int on the vertical axis and r int r min on the horizontal axis axial ratio diagrams are also used to depict the progressive change in vri shape with coalification standard deviations of the principal reflectance axes as measured on oriented cores average around 0 09 in magnitude and 5 in orientation measurements are highly reproducible between pairs of oriented cores estimates of the principal reflectance magnitudes as measured on oriented vs non oriented samples agree on average to within 0 04 for rmax 0 08 for rint and 0 20 for rint coal bearing strata in the north central coal fields medium volatile bituminous coal to semianthracite in northern pennsylvania were diagenetically altered in a predominantly burial strain environment and exhibit structural evidence of only mild tectonic deformation vris from this suite of coals are biaxial negative with rmin axes roughly perpendicular to bedding with increasing rank toward the southeast these vris plot along a straight line pathway on the axial ratio diagram emanating from near the origin and extending through the biaxial negative deformation field vris of coals from the western middle anthracite field exhibit a wide range of shapes and orientations which is indicative of a more complex tectonic history in their present day orientation rmin axes are scattered about a great circle distribution the pole to which is precisely coincident with regional fold axes when beds are unfolded to a flat lying orientation they become significantly less scattered indicating that most coalification here preceded the final phase of alleghanian folding rmax axes of sporinite grains are alwayas aligned parallel to bedding which suggests that the strata were still flat lying and not subject to tectonic forces when the coals passed through the 1st and 2nd coalification jumps

evaluation of the structure of bituminous coal from sośnica mine in the upper silesian coal basin poland using reflectance indicating surface ris parameters abstract the effect of a magmatic intrusion on the optical properties reflectance anisotropy and optical character of vitrinite in low rank bituminous coals was examined the study focused on coal samples collected at different distances from an intrusion emplaced into seam no 416 in so nica mine near gliwice in the upper silesian coal basin poland in the immediate contact zone coal transformed into natural coke may be seen for comparison laboratory carbonization of coals weakly changed or apparently unchanged by the intrusion was carried out the results obtained confirmed that during carbonization of the low rank coal heating alone with no external pressure makes possible the reorganization of carbon planes that is responsible for the increase of vitrinite reflectance the heating leads to the destruction of coal structure cross linkages aliphatic groups or heteroatoms and various further transformations of the structural net in addition to the removal of volatile carbonization products external pressures affect the transformation process especially by promoting the rearrangement of small structural units to form further elements of anisotropic structure thus in the case of coal from the immediate contact of the intrusion pressures resulted in values of anisotropy parameters higher than those characterizing coal heated in the laboratory up to 1200 c but in the absence of stress the source of pressure that strongly affected the coal in the mine was probably intrusion related weak tectonism in the region of the so nica mine could explain the fine biaxial optical character of the low rank parent coals more generally pressures associated with thermally evolving gasses conceivably led to the growth of structural anisotropy in the walls of degassing pores finally some structural changes seen in coal adjacent to the intrusion may reflect hydrothermal activity

fossil horses and carbon isotopes new evidence for cenozoic dietary habitat and ecosystem changes in north america abstract the transformation from low crowned to high crowned horse teeth during the miocene has traditionally been interpreted as an adaptive response to the spread of savanna grasslands during the middle miocene by about 15 m y ago carbon isotope data from 50 north american horse teeth spanning eocene to pleistocene age indicate that savanna grasslands presumably dominated by c 4 grasses as they are today first became widespread much later than do horses with high crowned teeth prior to 7 m y horses had a c 3 based diet and after 7 m y horses started eating c 4 grasses this change in diet occurred when the major drop in the diversity of horses occurs during the late miocene the change in vegetation reflected in horses diet may be related to a significant reduction in atmospheric co 2 level toward the end of the miocene which provided the c 4 grasses with an adaptive advantage and led to their expansion at the expense of c 3 plants

oxygen isotope variations in phosphate of biogenic apatites iv mammal teeth and bones groups of rats grown from birth to death in identical conditions but with different 18o of drinking water w were studied for variations of 18o of their body water bw and bone phosphate p there is a high linear correlation r 0 99 between bw and between p and w the regression lines have similar slope coefficients 0 53 and 0 49 values of p of different teeth and bones are the same within the precision of the method 0 5 the isotopic fractionation coefficient between phosphate and body water is 1 0178 and close to the estimated value of 1 0173 derived from the phosphate paleotemperature equation deviations from constant fractionation between bone phosphate and environmental drinking water depend primarily on rates of drinking and metabolism environment conditions have relatively little effect on oxygen isotope fractionation between water sources and bone phosphate

rare earth element behaviour associated with strata bound scheelite mineralisation broken hill australia abstract strata bound scheelite mineralisation occurs within calc silicates of a metamorphosed proterozoic volcano sedimentary sequence and is spatially related to lenticular bodies of basaltic volcanics tourmalinites and quartz gahnite rocks a pre metamorphic alteration halo has been detected within the enclosing basalts in the form of elevated fe as and eu contents which were formed by reducing and or high temperature hydrothermal fluids changing eh conditions during alteration gave rise to ce enriched basalts and sediments proximal and distal to the mineralisation the calc silicate horizon represents a hydrothermally altered and metamorphosed carbonate rich sediment as indicated by calc silicate pods containing primary sedimentary ree patterns the calc silicate horizon displays a lateral zonation from an unmineralised hydrothermally altered lree depleted core to mineralised lree depleted hree and eu enriched margins the wide range of ree patterns and the distinctive variation in ree spectra from the centre to the margins is due to the progressive dissolution of carbonates and the deposition of scheelite with decreasing temperature from the w fe as eu enriched ore fluids

biologic and climatic signals in the oxygen isotopic composition of eocene oligocene equid enamel phosphate abstract oxygen isotope results for tooth enamel phosphate p from late eocene early oligocene fossil horses are presented to determine if paleobiologic and paleoclimatologic information is recorded in fossil tooth enamel chemistry teeth from jaws of mesohippus and miohippus from the white river formation or group in the western great plains are well preserved and have excellent geochronologic control although there is clear evidence for post depositional alteration of the enamel a hydroxylapatite mineralogy is preserved and isotopic exchange of oxygen does not appear to be significant there are distinctive patterns of p variation among individual teeth from the same jaw these patterns reflect season of birth and timing of enamel mineralization most of the horses were born in the spring and mineralization of the enamel is complete after 1 1 5 years these results show that paleoclimate reconstruction from enamel p must account for tooth position and timing of mineralization the observation that there are different intrajaw patterns of p variation among mesohippus and miohippus may provide a basis to reconstruct changes in climate seasonality in ancient environments

geologic sulfur isotope and fluid inclusion studies of the sannae w mo mine republic of korea comparison of sulfur isotope systematics in korean w deposits the sannae tungsten molybdenum mine is located approximately 60 km north of pusan within the gyeongsang basin of the southern korean peninsula the hydrothermal vein type deposits which comprise the mine occur within an upper cretaceous magnetite series quartz monzonite stock which intrudes middle cretaceous sedimentary and volcanic rocks mineralization can be separated into three stages with declining temperature early molybdenum main tungsten and late carbonate stages fluid inclusion data suggest that most of the molybdenite was deposited at temperatures between 550 degrees and 350 degrees c wolframite and scheelite between 450 degrees and 300 degrees c and carbonates between 300 degrees and 180 degrees c salinities of mineralizing hydrothermal fluids ranged from 5 to 25 equiv wt percent nacl with a marked decrease in salinity between main tungsten and late carbonate stages fluid inclusion evidence of boiling suggests a range of pressures from about 100 to 300 bars this range is consistent with a depth of mineralization near 1 250 m under pressure conditions that alternated between hydrostatic and lithostatic sulfur isotope compositions of sulfides from the mine have the following ranges of delta 34 s values molybdenite 5 2 to 6 0 per mil and pyrite 6 0 to 7 1 per mil the delta 34 s sub h 2 s values calculated for these minerals are consistent with an igneous source of sulfur with a delta 34 s sub sigma s value near 4 0 to 5 0 per mil the geology mineral paragenesis and sulfur isotope and fluid inclusion data of the sannae w mo mine are very similar to data from other korean tungsten deposits the total range of delta 34 s sub h 2 s values of sulfides for all the korean tungsten deposits is 2 to 7 per mil however there is a narrow range of delta 34 s values for individual deposits the sulfur isotope compositions and systematics of korean tungsten deposits are nearly identical to those of japanese deposits associated with magnetite series granitoids and may be explained by the separation of a sulfur bearing magmatic fluid from a granitic melt under different oxidizing conditions

oxygen isotope analyses of co existing carbonate and phosphate in biogenic apatite a way to monitor diagenetic alteration of bone phosphate abstract the oxygen isotopic composition of phosphate 18 op and structural carbonate 18 oc of hydroxylapatite was determined in 31 bone and tooth samples of modern mammals from different countries these two variables are highly correlate r 2 0 98 and the calculated best fit of linear regression is very similar to the equation calculated from the phosphate and carbonate palaeotemperature equations 1 2 according to previous measurements 3 6 on fossils of different ages from different areas it seems quite improbable to find isotopically altered skeletal remains showing a good correlation between 18 op and 18 oc as is the case with modern samples it therefore seems possible at least in some cases to use these measurements for monitoring fossil bone and tooth diagenetic alteration when a set of points lie on the equilibrium line or close to it the 18 o values could be considered close to the original values in contrast when the points lie to the left or to the right of this line this probably means that the values are diagenetically modified due to interaction with meteoric water or 18 o enriched water respectively

oxygen isotope variation in the tusks of extinct proboscideans a measure of season of death and seasonality centimetre scale laminae in tusk and molar dentine of late pleistocene mastodonts and mammoths have been interpreted as annual growth bands produced in part by seasonal variation in growth rate to test this interpretation we measured the oxygen isotope composition 18 o of the co 3 fraction of dentinal hydroxyapatite from samples covering consecutive inferred years of growth in tusks in mammals changes in the 18 o value of dental tissues within individuals predominantly reflect variation in the 18 o value of body fluids which is controlled mainly by the isotopic composition of ingested water in northern hemisphere continental regions winter precipitation has substantially lower 18 o values than does precipitation in other seasons if ingested water tracks focal precipitation then seasonal variations in dentinal isotope composition should result the lowest 18 o values representing winter growth we demonstrate that there are substantial variations in the oxygen isotope composition of proboscidean dentinal apatite and that isotopic identifications of winter i e low 18 o values coincide with those based on growth rate i e slow growth zones finally the potential of oxygen isotope analyses of terrestrial mammals for assessing the seasonality of paleoclimates is considered

isotopic reconstruction of past continental environments abstract vertebrate fossils and continental sediments provide a rich record of variations in the isotopic composition of surface environments to interpret these records a greater understanding of isotopic sources as well as fractionations associated with animal physiology soil geochemistry and diagenesis has been essential tooth enamel and fish otoliths yield subannual records of surface environments whereas soil minerals may integrate signals over many thousands of years carbon isotope variations in fossil vertebrates and soils record changes in the structure of vegetation and the isotope composition and concentration of atmospheric co2 oxygen isotope variations may be indirectly related to climate through reconstruction of the oxygen isotope composition of meteoric water or directly related to temperature through application of oxygen isotope paleothermometry to soil minerals or otoliths in africa nitrogen isotope variations show promise as a proxy for rainfall abundance though the gen

paleobiology and skeletochronology of jurassic dinosaurs implications from the histology and oxygen isotope compositions of bones fossil biogenic phosphate of fast growing primary bone tissue of dinosaurs can preserve a histologic and isotopic time series of annual seasonality in temperature variations similar to tooth enamel and other accretionary skeletal phases such as corals or wood on two bone fragments from sympatric dinosaurs with different histologic patterns of bone growth high resolution oxygen isotope profiles were analyzed along the radial direction of bone growth the investigated specimens are from the jurassic shishugou formation in the junggar basin nw china and have distinct patterns of compositional variation a fibrolamellar dinosaur bone with multiple lines of arrested growth lags and periodic growth cycles of decreasing bone laminae thickness displays a cyclic intra bone variation in 18o values of about 2 corresponding with the lags these growth cycles in fast growing fibrolamellar bone provide evidence for seasonal growth of dinosaurs in lower latitudes 45 n possibly influenced by a monsoon type paleoclimate seasonal changes in temperature and water supply are consistent with the oxygen isotope composition measured in dinosaur bone phosphate as well as with growth rings in contemporaneous fossil conifer wood from the same locality in contrast a plexiform sympatric sauropod bone displays continuous growth free of lags and has a lower intra bone variation of 0 8 differences in bone histology are also reflected in the oxygen isotopic composition and its intra bone variability indicating different physiological responses to external climatic stress between sympatric dinosaur species seasonal intra bone oxygen isotope variations combined with bone histology may thus yield new insights into species specific response to climatic stress and its influence on dinosaur growth formation of growth marks growth rates as well as dinosaur thermophysiology

sulfur isotope studies of the felbertal scheelite deposit eastern alps the felbertal scheelite deposit is the largest known strata bound tungsten concentration it lies in an up to 400 m thick rock pile in the lowermost part of the volcanic rock sequence probably of the early paleozoic habach formation both ore fields eastern and western have been affected by variscan and alpine metamorphism and tectonism resulting in a remobilization of the ore mineralization this ore deposit and the neighboring rocks show a strikingly low sulfur content the eastern field with one major orebody has very little sulfide mineralization the western field with 8 orebodies k1 k8 and two remobilized vein zones s1 and s2 reveals somewhat more minor sulfide enrichments that are mainly within and around the k1 and k2 orebodies and in some parts of the interlayered schist sequence sulfur isotope compositions of 90 sulfide minerals 37 pyrrhotite 20 chalcopyrite 19 pyrite and 11 molybdenite and or ws2 mos2 solid solutions and 3 pb bi sulfosalts including 7 sulfides within scheelite grains from 60 ore and host rock samples have been determined with a standard error of less than 0 2 per mil all data range from 3 6 to 4 3 34s there are small differences in the sulfur isotope values from place to place and in time from the first and second to the third generation in the western field the k1 orebody differs from other orebodies k2 k4 k7 due to isotopically heavier 34s values the three scheelite generations show differences in the 34s values of the sulfide microphases within scheelite grains from 1 0 to 4 3 per mil for the first and the second and from 1 8 to 3 3 per mil for the third generation sulfide phases within molybdoscheelites may have crystallized under the same conditions as the other coeval sulfide minerals in the same orebody they commonly formed later than scheelite these changes may be explained using data from ohmoto and rye 1979 small changes in temperature ph and or f o 2 may result in large changes in the 34s values with the precipitation of isotopically heavier sulfides under more reducing conditions only four samples with sulfide mineral pairs show isotopic equilibrium all others display some disequilibrium we suggest that the sulfides in the ores and surrounding volcanogenic host rocks formed contemporaneously from the same hydrothermal ore fluids and that the sulfur species in these fluids may have been dominantly h2s

recognition of vitrinite with non uniaxial negative reflectance characteristics non uniaxial negative reflectance characteristics are being reported for coals from around the world with increasing frequency these data have traditionally been collected from oriented sections cut from a block of coal to determine the magnitudes of the principal reflectance axes to make data collection less time consuming a method of determining the principal reflectance axes from a standard crushed coal sample has been developed the method requires measurement of the maximum and minimum apparent reflectances from a series of randomly oriented vitrinite particles the reflectance crossplot displays these two reflectance values against their difference or bireflectance the paper describes the method of interpreting the resultant pattern to determine the values of the three principal reflectance axes analysis of coals from the british columbia rocky mountains and foothills revealed biaxial and uniaxial positive as well as uniaxial negative reflectance characteristics a new measure of maturation rev is proposed which is based purely on the lengths of the three principal reflectance axes rm approximates this value but is influence by any eccentricity of the reflectance indicating surface ris vitrinite with a non uniaxial reflectance characteristics cannot be adequately described by a single measure such as rmaxorrm but requires reference to both the size and shape of the ris a reflectance determination such as rev or rm provides rank astm information whereas the new measures rst and ram describe a reflectance indicating surface shape which is the result of maturation and tectonic histories vitrinites with non uniaxial negative reflectance characteristics are abundant in the coalfields of the rocky mountains and foothills of british columbia rmax does not fully describe the reflectance character of these coals and does not describe the potentially useful ris shape

coal metamorphism by igneous intrusion in the raton basin co and nm implications for generation of volatiles abstract the raton basin contains a series of tertiary mafic dikes and sills that have altered millions of tons of coal to natural coke and may have played a minor role in generating some of the large coalbed methane resources currently being exploited in this region four outcrops within the raton basin were selected to investigate local coal rank elevation and volatile generation due to intrusive activity coal and organic shale samples were collected on traverses across meter scale dikes and sills and were analyzed for vitrinite reflectance total organic carbon bulk carbon isotopic ratios and coke petrography reflectance patterns in the contact aureoles of the dikes display very consistent concave up patterns with reflectance values returning to background within one intrusion width from the contact bulk coal samples collected across dikes display an increase in 13c of approximately 1 approaching all contacts reflectance patterns within the contact aureoles of sills do not decrease significantly until one half of an intrusion width away from the contact but then drop steeply to background values by one intrusion width away bulk coal samples display complex isotopic patterns approaching sills with an initial increase in 13c followed by a steep decrease of approximately 1 5 approaching the top contacts the distinct isotopic and reflectance patterns for dikes and sills may indicate that the coal in the contact aureoles of the sills experienced a longer heating duration than the coal near the dike contacts this longer heating duration was due to the low thermal conductivity of coal which acts as a thermal insulator to the sills that intrude coal beds this style of intrusion is commonly observed throughout the central portions of the raton basin by contrast dikes intrude a variety of country rock types and are not insulated by coal heat may escape the contact zone through nearby sandstones or shales based on reflectance patterns hydrothermal convection played a role in heat transfer away from dikes data from both the dike and sill contacts suggest that time plays a role in controlling peak vitrinite reflectance values at least over the short heating durations tens of years expected for meter scale intrusions decreasing total organic carbon values approaching all contacts suggests the generation and escape of volatile species such as methane isotopic values within the contacts of dikes are consistent with the loss of 12c enriched methane the isotopic pattern observed at the contacts of sills may be due to accumulation of 12c rich pyrolytic carbon close to the contacts which is supported by petrographic observations even though multiple thin sheet intrusions are insignificant for conductive heating on a basin scale methane generation by sheet intrusions was volumetrically important in the raton basin because sills preferentially intrude coal beds in this region

evolution of fluids and metamorphic ore remobilization in the felbertal scheelite deposit eastern alps abstract the felbertal scheelite deposit displays a variety of host rocks and ore types macroscopic and microscopic evidence indicates the formation of the ore mineralization in a geothermal system including explosion and subaqueous surface phenomena at an active continental margin in upper proterozoic upper riphaean lower vendian time the alpine metamorphism and tectonism caused a pervasive metamorphic hydrothermal ore redeposition and a spatial redistribution from smaller volumes to larger volumes of low grade ores especially in the western field microthermometrical studies on quartz scheelite beryl calcite and fluorite in the metamorphosed felbertal scheelite deposit show two types of fluid inclusions aqueous fluid inclusions with variable amounts of co 2 up to 20 wt as well as aqueous fluid inclusions without a measurable co 2 content both types are of alpine origin and were trapped during the alpine retrograde metamorphism therefore the microthermometrical data do not record the conditions of the original pre alpine tungsten formation however it was possible to construct a path for the fluid evolution and the cogenetic ore redeposition during the alpine retrograde metamorphism from the microthermometrical and petrographical data

oxidatively and thermally altered high volatile bituminous coals in high temperature coal fire zone no 8 of the wuda coalfield north china abstract coal fires have received increasing attention due to their environmental economic and social impacts their significant influence on coal properties is widely documented by geophysical and geochemical methods the present paper demonstrates by means of coal petrological methods significant changes of microstructure optical appearance and optical properties of medium rank bituminous coals affected by an underground coal fire the studied changes are suggested to result from distinct oxidative and thermal alterations induced by a high temperature regime temperatures over 800 c encountered in the coal fire zone no 8 wuda coalfield the investigated coal seam no 9 represents a high volatile a bituminous coal and is dominated by vitrinite followed by inertinite with minor amounts of liptinite the microstructure of the coal fire affected coals facilitate a broad spectrum of characteristic features the microscopic analyses revealed development of 1 non tectonic fissures and non tectonic fractures 2 distinct micropores 3 dark oxidations rims and 4 bright spots interpreted as incipient mesophases optical properties were characterised for megasporinite and vitrinite in the examined megasporinite a noticeable anisotropy and distinct granular appearance was observed in the investigated coals both a dominant increase as well as a minor decrease in both random and maximum vitrinite reflectances were documented for 1 coal grains and 2 dark rimmed vitrinite at non tectonic fissures and non tectonic fractures in addition also a characteristic bimodal vitrinite population was measured the increase in bireflectance was clearly documented for two sub zones within the coal fire zone no 8 the applied kilby s cross plots suggested a large overlapping of the data sets of r max and r min indicating marked changes in vitrinite structure the applied coal petrological approach revealed distinct changes to the coal s microstructure appearance as well as to optical properties induced by the underground coal fire the presented coal petrographic approach may help determine the extent of coal fires in coal mines and the direction of propagation of coal fire front

influence of a basic intrusion on the vitrinite reflectance and chemistry of the springfield no 5 coal harrisburg illinois abstract the springfield no 5 coal a pennsylvanian age high volatile b bituminous rank coal in the carbondale formation is mined in the southeastern section of the illinois basin intruded into this coal is a 10 1 m wide basic dike that is near vertical through the extent of the mined coal bed and strikes n 22 w the intrusion and the effects it had on the coal were studied petrographically and geochemically using a published heat flow model by carslaw and jaeger 1959 carslaw h s jaeger j c 1959 conduction of heats in solids oxford university press in conjunction with thin section microscope analysis a contact temperature of 600 c was determined vitrinite reflectance was measured for a suite of coal samples collected distal to the intrusion vitrinite reflectance values rose uniformly from the ambient reflectance values of 0 69 at just greater than one dike thickness away to 5 at the dike coal contact the increase in reflectance values for samples within 1 2 times dike thickness is concordant with data published by bostick and pawlewicz 1984 bostick n h pawlewicz m j 1984 paleotemperatures based on vitrinite reflectance of shales and limestones in igneous dike aureoles in the upper cretaceous pierre shale walsenburg colorado in woodward j g meissner f f clayton j l eds hydrocarbon source rocks of the greater rocky mountain region rocky mountain association of geologists pp 387 392 on the effects of mafic intrusions into cretaceous age shales in walsenburg colorado comparison of colorado data with data from these sites indicates that despite differences in intrusion temperature timing or coal rank at time of the intrusion ambient mean vitrinite reflectance values remain unchanged at just greater than one dike width from an intrusion

reflectance anisotropy and syn deformational coalification of the jewel seam in the cadomin area alberta canada abstract the jewel seam of the cadomin area is complexly folded and cut by several thrust faults vitrinite reflectance anisotropy was determined from twenty oriented coal blocks collected from various structural positions five of the blocks have uniaxial anisotropies five have biaxial positive anisotropies the remaining ten are biaxial negative the biaxial coals display maximum reflectance axes parallel to nearby fold axes which suggests a relationship between vitrinite anisotropy and deformation the biaxial vitrinite reflectance ellipsoids result from superposition of tectonic strains on a primary sedimentary burial related uniaxial anisotropy a tectonic stress field was probably present during the later stages of sedimentary burial and subsequent deformation coalification resulted largely from pre deformational sedimentary burial but the final coalification stage was syn deformational as illustrated by the intersection of isorank surfaces and the jewel seam and the biaxial vitrinite reflectance anisotropy

on the optically biaxial character and heterogeneity of anthracites abstract the results of the study of optical properties of 13 anthracites from different parts of the world are presented in this paper measurements of reflectance values were made on non oriented vitrinite grains for a minimum of 300 points per sample the reconstruction of reflectance indicating surfaces ris were made by kilby s method kilby w e 1988 recognition of vitrinite with non uniaxial negative reflectance characteristics int j coal geol 9 267 285 kilby w e 1991 vitrinite reflectance measurement some technique enhancements and relationships int j coal geol 19 201 218 it was found that the use of kilby s method for strongly anisotropic materials like anthracites did not give unambiguous results some improvement in kilby s method consisting of the division of the cumulative cross plot into several elemental components is suggested each elemental cross plot corresponds to a textural class of anthracite which is characterized by the values of ris main axes rmax k rint k and rmin k k 1 2 n n number of classes the global texture of anthracite is characterized as a ris with main axes calculated as the weighted means of r max r int and r min for each class of this anthracite the division of cumulative kilby s cross plot on elemental components makes possible the calculation of new coefficients ht and h10 characterizing the heterogeneity of the structure and texture of anthracites the results of our study show that all anthracites have biaxial negative textures but their heterogeneity varies in a wide range of ht and h10 coefficients depending upon the individual coal basin

mineralogy and geochemistry of the no 6 coal pennsylvanian in the junger coalfield ordos basin china abstract this paper discusses the mineralogy and geochemistry of the no 6 coal pennsylvanian in the junger coalfield ordos basin china the results show that the vitrinite reflectance 0 58 is lowest and the proportions of inertinite and liptinite 37 4 and 7 1 respectively in the no 6 coal of the junger coalfield are highest among all of the late paleozoic coals in the ordos basin the no 6 coal may be divided vertically into four sections based on their mineral compositions and elemental concentrations a high boehmite content mean 6 1 was identified in the no 6 coal the minerals associated with the boehmite in the coal include goyazite rutile zircon and pb bearing minerals galena clausthalite and selenio galena the boehmite is derived from weathered and oxidized bauxite in the weathered crust of the underlying benxi formation pennsylvanian a high pb bearing mineral content of samples zg6 2 and zg6 3 is likely of hydrothermal origin the no 6 coal is enriched in ga 44 8 g g se 8 2 g g sr 423 g g zr 234 g g rees 193 3 g g hg 0 35 g g pb 35 7 g g and th 17 8 g g gallium and th in the no 6 coal mainly occur in boehmite and the pb bearing selenide and sulfide minerals contribute not only to se and pb contents in the coal but also probably to hg content a high zr content is attributed to the presence of zircon and sr is related to goyazite the rees in the coal are supplied from the sediment source region and the rees leached from the adjacent partings by groundwater

formation temperatures of natural coke in the lower silesian coal basin poland evidence from pyrite and clays by sem edx abstract the purpose of this paper is to show how sem edx can be applied in a study of coals altered to coke by a magnetic intrusion sem photographs reveal some textural features of a natural coke which would not be detectable using optical microscopy the similarity between images of natural and artificial coke is proof that temperatures over 350 c were experienced during contact metamorphosis crystal shapes of minerals are presented as evidence of hydrothermal activity in the contact zone and an average temperature level below 575 c pyrite is used as a geological thermometer its shape and composition showing the occurrence of incidental hot spots 750 c in contact with the dyke

triassic environments climates and reptile evolution abstract a consideration of all the available data on triassic vertebrate faunas and their stratigraphic location reveals a relatively sudden extinction event among the last of the mammal like reptiles and the herbivorous rhynchosaurs in the norian of the upper triassic this event was apparently quickly followed by the radiation of the dinosaurs also in the norian this conclusion suggests that competition was not the main factor in the initial success of the dinosaurs but opportunistic radiation following the extinction of major reptile groups a global review of triassic sedimentary facies shows that there were climatic and floral changes towards the end of the triassic it is envisaged that increasing aridity in the later triassic resulting from plate motions and particularly affecting gondwanaland and southwestern laurasia brought about floral changes and then the reptile extinctions with the rapid evolution of new floras of conifers and bennettitaleans the dinosaurs came to dominate all terrestrial faunas within the space of only a few million years

changes in carbon isotope ratios in the late permian recorded in therapsid tooth apatite the end of the permian witnessed global extinctions of marine and terrestrial fauna1 as marine biogenic carbonate and atmospheric carbon dioxide are in long term isotopic equilibrium changes in carbon isotope ratios in marine carbonate strata should record changes that occurred at that time in atmospheric ratios one might then expect a correlation between 13c 12c ratios in such marine sequences and those in terrestrial records that derive from carbon bearing materials that incorporate atmospheric co2 an example of the latter is fossil tooth apatite from herbivorous fauna correlations of this sort between marine and terrestrial records are however difficult to establish as they rely on particular characteristics of the isotope curves here we show that stable carbon isotope ratios in tooth apatite from diictodon a mammal like reptile in the late permian lower beaufort succession of the south african karoo 260 245 myr show a progressive depletion in 13c that is very similar to trends in marine carbonates from late permian deposits in eurasia2 7 these results suggest that global changes in total biomass occurred towards the end of the permian primary production decreased and continental aridity increased8 leading to a depletion of 13c in atmospheric and oceanic co2

metamorphosed hydrothermal eruption breccia conglomerate in the felbertal scheelite deposit eastern alps austria abstract a metamorphosed hydrothermal eruption breccia conglomerate has been found in recently opened galleries in the western field of the felbertal scheelite deposit it belongs to the k2 ore body and covers a stratiform quartz mass and surrounding host rocks the quartz mass shows features very similar to siliceous sinters in recent explosion craters e g waiotapu new zealand the breccia displays a variable thickness commonly up to 60 cm it is continuous for at least 100 m along strike and is composed of rock fragments from the surrouding and underlying host rocks including basaltic felsic and quartz rocks these fragments reveal a variable degree of rounding due to subaqueous reworking and an elongation due to tectonism and metamorphism with increasing distance from the quartz mass the quantity of rock fragments in the breccia diminishes rapidly laterally the metamorphosed breccia conglomerate horizon interfingers with biotite amphibolites this breccia indicates 1 at least one hydrothermal eruption 2 the existence of a subaqueous erosional surface 3 the ejection of underlying and surrounding host rocks of the scheelite bearing series 4 the pre existence of the quartz mass and a bimodal rock assemblage including basaltic and felsic volcanites with an earlier tungsten mineralization mainly in quartz fragments and 5 a tungsten mineralization coeval with the formation of the matrix this matrix shows enrichments in w sn mo li be au bi as f p ba th and u

age and evolution of scheelite hosting rocks in the felbertal deposit eastern alps u pb geochronology of zircon and titanite u pb isotope analyses of zircon and titanite extracted from different rocks of the felbertal scheelite deposit yield the following information 1 an age of 593 22 ma 2 is obtained for zircon crystallization in the scheelite bearing matrix of an eruption breccia in the western ore field 2 discordant zircons from an elongated up to 8 m thick scheelite rich quartzite body in the eastern ore field give an upper intercept age of 544 5 ma this quartzite contains a laminated fine grained scheelite mineralization 3 zircons from a small granitoid intrusion of the western ore field reveal an age of 336 16 ma and concordant titanites document an age of 282 2 ma for variscan amphibolite facies metamorphism both events granitoid intrusion and later metamorphism caused ore re mobilization including the formation of yellowish fluorescent molybdo scheelite porphyroblasts 4 for a narrow lamprop 1hyric dike in the western ore field a concordant titanite age of 283 7 ma is obtained this age is identical with the titanites from the amphibolite facies metamorphic intrusion tiny scheelite grains were tapped by the dike from pre existing scheelite mineralizations in the truncated host rocks 5 alpine metamorphism at 31 4 ma did not exceed lowermost amphibolite facies conditions and it caused scheelite re mobilization on a minor scale only producing bluish fluorescent porphyroblasts in quartz veinlets and veins as well as bluish fluorescent scheelite rims around older scheelite grains moreover crosscutting alpine fissure fillings show bluish fluorescent inclusion free scheelite 6 the preservation of variscan titanites the absence of alpine titanite growth and the large degree of variscan scheelite re mobilization demonstrate that amphibolite facies metamorphism in the felbertal area has a variscan age this result clearly documents variscan tectono metamorphism to be the dominant event instead of the hitherto surmised alpine metamorphism this multi stage evolution of the felbertal ore bodies corroborates the view that tungsten deposits are conditioned by several succeeding thermal events leading to a series of stages that ultimately produce high grade scheelite concentrations these high grade ores predominately occur along shear zones of different age accompanied by the formation of large volumes of low grade scheelite mineralizations along host rock foliations and quartz veinlets and veins

the palaeoecology of the non mammalian cynodonts diademodon and cynognathus from the karoo basin of south africa using stable light isotope analysis abstract the palaeoecology of the coeval middle triassic non mammalian cynodonts diademodon and cynognathus therapsida remains poorly understood although their gross morphology has been studied intensively significant differences in their growth patterns suggest inherent biological differences despite having inhabited similar environments in this study the palaeoecology of cynognathus and diademodon specimens were examined using intra tooth stable carbon and oxygen isotope analyses of enamel carbonate the resulting stable isotope patterns of cynognathus and diademodon were compared with that of crocodylus niloticus and published mammalian tooth enamel data predictably the non mammalian cynodont 13 c values fall within the expected range for c 3 plant diets both 18 o and 13 c values of diademodon are markedly more depleted than those of cynognathus suggesting that the former fed in shadier damper areas was nocturnal and or depended more directly on environmental water the seasonal amplitude reflected in the cynognathus teeth is relatively low however high amplitude directional 18 o intra tooth variations in the diademodon teeth are comparable to or higher than those observed for extant mammalian and c niloticus teeth from semi arid seasonal regions this suggests that marked seasonality prevailed in the karoo basin during the middle triassic and that diademodon was sensitive to these variations these isotopic differences between diademodon and cynognathus indicate differing responses to climatic fluctuations and reveal new insights into the palaeoecology of non mammalian cynodonts

vitrinite anisotropy resulting from simple shear experiments at high temperature and high confining pressure abstract orientations of r 0 max and r 0 min of vitrinite have been determined in coal samples that have been deformed in simple shear experiments at t 650 900 c confining pressures of 0 8 and 1 0 gpa and constant displacement rates of 10 5 10 6 s 1 samples chosen are a high volatile bituminous coal and two anthracites shear strains up to 3 0 were attained in experiments that lasted up to 100 h high temperature and large strains have facilitated an increase in r 0 max an increase in anisotropy bireflectance and reorientation of r 0 max and r 0 min results of these experiments indicate that tectonic strain at and above semi anthracite rank enhances the degree of molecular ordering leading to preferential growth of graphite and that vitrinite anisotropy may track with tectonic strain