climate instability during the last interglacial period recorded in the grip ice core isotope and chemical analyses of the grip ice core from summit central greenland reveal that climate in greenland during the last interglacial period was characterized by a series of severe cold periods which began extremely rapidly and lasted from decades to centuries as the last interglacial seems to have been slightly warmer than the present one its unstable climate raises questions about the effects of future global warming

reconstructing biomes from palaeoecological data a general method and its application to european pollen data at 0 and 6 ka biome models allow the results of experiments with atmospheric general circulation models to be translated into global maps of potential natural vegetation the use of biome models as a diagnostic tool for palaeoclimate simulations can yield maps that are directly comparable with palaeoecological pollen and plant macrofossil records provided these records are biomized i e assigned to biomes in a consistent way this article describes a method for the objective biomization of pollen samples based on fuzzy logic pollen types taxa are assigned to one or more plant functional types pfts then affinity scores are calculated for each biome in turn based on its list of characteristic pfts the pollen sample is assigned to the biome to which it has the highest affinity subject to a tie breaking rule modern pollen data from surface samples reflecting present vegetation across europe are used to validate the method pollen data from dated sediment cores are then used to reconstruct european vegetation patterns for 6 ka the reconstruction shows systematic differences from present that are consistent with previous interpretations the method has proved robust with respect to human impacts on vegetation and provides a rational way to interpret combinations of pollen types that do not have present day analogs the method demands minimal prior information and is therefore equally suitable for use in other regions with richer floras and or lower densities of available modern and fossil pollen samples than europe

variable alteration in heavy crude oils of west central saskatchewan canada heavy crude oils occurring in the mississippian bakken and lower cretaceous mannville reservoirs in west central saskatchewan display variable geochemical composition in their light c 5 c 8 and medium c 12 c 30 molecular weight fractions all oils show a depletion of normal alkanes and to a lesser extent acyclic isoprenoids which appears to increase progressively southward as biodegradation seems to be the primary control of the n alkane distributions it appears that oils produced from deeper reservoirs in the south are more biodegraded than the oils in shallower mannville reservoirs in the north however several other compositional characteristics including gasoline range and aromatic fractions are inconsistent with the trend in biodegradation defined by the relative n alkane abundance oils from the shallower northern reservoirs are enriched in cycloalkanes show lower relative concentrations of isoheptane lower paraffin indices much higher kl ratios and lower relative concentrations of lower molecular weight naphthalenes moreover some oils show a persistent presence of lower homologs of n alkanes c 5 c 8 and light aromatics such as benzene and toluene when higher c 15 homologs are not present such compositional characteristics may indicate that some of the reservoirs containing biodegraded oil were subjected to a subsequent secondary charge of lighter unbiodegraded crude or to different post generative alteration mechanisms this later charge of light hydrocarbons suggests the timing of most biodegradation to be pre eocene destructive microbial action resulting in preferential removal of n alkanes isoprenoids alkylbiphenyls and methylated naphthalenes had little effect on higher molecular weight fractions therefore despite their apparently very low gravities average api of 14 most of these oils suffered only light to moderate biodegradation although generally similar biomarker signatures indicate an overall genetic affinity and the same source rock for these oils minor but systematic variations in the biomarker compositions likely reflect regional source organic facies variation or indicate a progressive change in oil maturity

atlas of pollen spores and further non pollen palynomorphs recorded in the glacial interglacial late quaternary sediments of lake suigetsu central japan abstract the record of well preserved palynomorphs from sediment samples of lake suigetsu mirrors temporal changes in the flora around the lake and spatial changes in the vegetation cover of central japan during the late quaternary this study presents photographic images of 169 identifiable types of moss lycophyte and fern spores and pollen of gymnospermous and angiospermous plants from the sg06 core sediment obtained at a standard magnification of ca 750 additionally non pollen palynomorphs npps which appeared in the pollen slides are documented including remains of fungi rhizopods arthropods rotifers flatworms as well as green algae and plant tissue fragments all documented taxa are presented in taxonomical order on 66 plates including 55 plates for pollen and spores of higher plants and 11 plates for npps this study renders an overview on quality of preservation and on the range of palynomorphs found in the last glacial interglacial sediments of lake suigetsu and furthermore may serve as a handy and thorough guide for palynological investigations aiming at the reconstruction of past vegetation environmental and climate dynamics

a geochemical study of oil migration at source rock reservoir contacts stable isotopes abstract whereas organic geochemical analyses of oils and potential source rocks have enabled correlations to be drawn and have been utilized to suggest modes of migration only limited data has been published relating a known source rock in contact with an oil filled reservoir this paper presents initial results from the examination of an approximately 100 m continuous core through the kimmeridge shale of the north sea the variability in extractable source rock hydrocarbon contents kerogen toc asphaltene and their carbon isotopic contents are documented nitrogen isotopic content of kerogens and asphaltenes as well as kerogen and asphaltene ton are relatively constant carbon isotopic compositions of kerogen extractable hydrocarbons and asphaltenes covaried significantly as did nitrogen isotopic compositions of kerogen and asphaltenes average isotopic compositions of the asphaltene free extracts and asphaltenes were nearly identical to the oil in the primary reservoir small chemical differences are noted among extracts

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

application of the pyrolysis carbon isotope method for determining the maturity of kerogen in the bakken shale a maturity indexing procedure based on the isotopic difference between the total accumulated methane produced by exhaustive pyrolysis and the kerogen 13c and the mole ratio of methane to kerogen carbon cmr has been tested by applying a standardized technique i e exhaustive pyrolysis 600 c for 120 hr of extracted powdered samples and measurement of the amounts and isotopic composition of the methane and kerogen carbon on a suite of 15 bakken shale samples a linear relation was found between the carbon mole ratio of pyrolysis derived methane and total organic carbon and the 13c difference between the pyrolysis derived methane and total organic carbon r 0 79 and between the amount of ch4 generated from exhaustive pyrolysis and h c atomic ratios r 0 91

re os geochronology of organic rich sediments an evaluation of organic matter analysis methods rhenium and osmium in organic rich sedimentary rocks are dominantly hydrogenous but any nonhydrogenous component will influence the accuracy and precision of the re os date obtained to minimize the influence of any nonhydrogenous re and os we evaluate analysis of isolated organic matter from the whole rock together with whole rock analysis using a cro3 h2so4 digestion medium instead of inverse aqua regia for a black shale unit of the exshaw formation canada this unit previously returned a whole rock re os date of 358 10 ma model 3 geochim cosmochim acta 2002 using inverse aqua regia dissolution organic matter isolated from the whole rock matrix using the hf bf3 technique org geochem 20 1993 249 yields scattered data and a re os date of 449 220 ma model 3 mswd 616 the organic matter analyses show similar 187os 188os values but significantly lower 187re 188os values in comparison to the whole rock analyses we show that the re os systematics of organic matter are altered during chemical isolation and as such we suggest that the hf bf3 method should not be used for re os analysis of organic matter whole rock re os analysis using a cro3 h2so4 digestion medium yields significantly better regression analysis compared with the inverse aqua regia method and the re os data identify two distinct initial 187os 188os values for the sample set separate regressions of these data yield precise dates 366 1 9 6 mswd 2 2 and 363 4 5 6 ma mswd 1 6 model 3 which are indistinguishable from the age constraints for this formation 363 4 0 4 ma u pb monazite comparison of the re os dates obtained from aqua regia and cro3 h2so4 methods suggests that the former may contain nonhydrogenous re and os whereas the cro3 h2so4 method dominantly liberates hydrogenous re os from organic matter allowing for better stratigraphic age determinations and evaluation of the os isotope composition of seawater

vegetation changes and associated climate variations during the past 38 000 years reconstructed from the shaamar eolian paleosol section northern mongolia abstract this study presents a pollen based reconstruction of the vegetation changes and associated climate variations at the shaamar eolian paleosol section in the northern mongolian plateau the semi quantitative reconstructions of paleovegetation types and temperature and moisture indices show that the vegetation in the shaamar area was a taiga forest dominated by picea abies and pinus sibirica type between 38 000 and 30 000 cal bp when the reconstructed moisture level was the highest of the past 38 000 years the vegetation during the ensuing period from 30 000 to 23 000 cal bp was mainly a steppe dominated by artemisia and poaceae under low temperature and relatively low moisture conditions the vegetation during the period from 23 000 to 10 000 cal bp varied from a taiga forest through steppe dominated by poaceae taiga forest and forest steppe to a taiga forest the climate was cold and relatively dry in the early phase 23 000 to 20 000 cal bp and warmer and somewhat drier in the later phase 19 000 to 11 000 cal bp the pollen assemblages and the vegetation zonal indices suggest that the vegetation was a forest steppe during the period from 10 000 to 3000 cal bp under rising temperature and low moisture conditions a taiga forest has dominated the landscape during the past 3000 years under cooling and wetting conditions comparison of our pollen record with other paleoclimatic records suggests that the climate changes in the northern mongolian plateau have been controlled or modulated by ocean atmospheric coupling dynamics in the north atlantic region

water and gas geochemistry of the euganean and berician thermal district italy between 1987 and 1995 more than 100 chemical and isotopic analyses were carried out on the thermal fluids discharged at surface from wells and springs of the euganean and berician thermal district results for dd and d 18 o in waters d 13 ci n co2 and in c1 c4 n alkanes d di n ch4 3 he 4 he and 40 ar 36 ar ratios in natural gases were coupled with chemical analyses in an attempt to determine the main characteristics and evolutionary trends of thermal fluids emerging in the region the isotopic and chemical composition of thermal waters has led to the postulation of a meteoric origin of discharged thermal fluids and of a maturation trend as water moves from the peripheral manifestations of the berici hills towards those of the battaglia montegrotto and abano springs in the inner part of the geothermal field numerical simulation suggested that the observed evolutionary path is consistent with diaerentiation due to processes of water rock interaction the results of bulk analyses have shown that the gases are made up mainly of n2 65 95 vol co2 0 5 20 5 vol and ch4 up to 10 vol with relatively high ar and he contents up to 1 5 vol and 0 16 vol respectively and detectable amounts of c2 c6 saturated hydrocarbons the chemical and isotopic composition of the gases suggests that both the meteoric and crustal contributions to the natural discharges are significant while any significant magmatic contribution possibly related to vestiges of the volcanic activity that occurred in the abano area during the tertiary age can be ruled out 2000 elsevier science ltd all rights reserved

fluid inclusions and h o s pb isotope systematics of the baishan porphyry mo deposit in eastern tianshan china abstract the baishan porphyry mo deposit formed in the middle triassic in eastern tianshan xinjiang northwestern china mo mineralization is associated with the baishan monzogranite and granite porphyry stocks mainly presenting as various types of hydrothermal veinlets in alerted wall rocks with potassic phyllic propylitic and fluorite alteration the ore forming process can be divided into four stages stage i k feldspar quartz pyrite veinlets stage ii quartz molybdenite pyrite veinlets stage iii quartz polymetallic sulfide veinlets and stage iv barren quartz calcite veins four types of fluid inclusions fis can be distinguished in the baishan deposit namely liquid rich two phase l type vapor rich two phase v type solid bearing multi phase s type and mono phase vapor m type inclusions but only the stage i quartz contains all types of fis the stages ii and iii quartz have three types of fis with exception of m type in stage iv quartz minerals only the l type inclusions can be observed the fis in quartz of stages i ii iii and iv are mainly homogenized at temperatures of 271 468 c 239 349 c 201 331 c and 134 201 c with salinities of 2 2 11 6 wt nacl equiv 1 1 10 2 wt nacl equiv 0 5 8 9 wt nacl equiv and 0 2 5 7 wt nacl equiv respectively the ore forming fluids of the baishan deposit are characterized by high temperature moderate salinity and relatively reduced condition belonging to a h 2 o nacl ch 4 co 2 system hydrogen and oxygen isotopic compositions of quartz indicate that the ore forming fluids were gradually evolved from magmatic to meteoric in origin sulfur and lead isotopes suggest that the ore forming materials came predominantly from a deep seated magma source from the lower continental crust the mo mineralization in the baishan deposit is estimated to have occurred at a depth of no less than 4 7 km and the decrease in temperature and remarkable transition of the redox condition from alkalinity to acidity of ore forming fluids were critical for the formation of the baishan mo deposit

three dimensional modeling study of the low permeability petroleum system of the bakken formation the bakken formation of the williston basin is a prime example of an unconventionally produced petroleum system with a low permeability reservoir that requires application of advanced technologies for commercial production a three dimensional model of the williston basin was constructed to integrate and assess the parameters that influence the generation and migration of hydrocarbons in the bakken formation this study tests the applicability of available basin and petroleum system modeling technology on an unusually low permeability petroleum system the model is based on nine surfaces constructed from log tops of thousands of wells in the study area and additional depth and isopach maps of the bakken formation members these were integrated with the established basin evolution in line with published research temperature and thermal maturity were calibrated during model construction from well temperature and geochemistry data the resulting heat flow map supports the existence of a heat flow anomaly along longitude 103w discussed controversially in the literature furthermore the results indicate that the invasion percolation migration approach best describes the distribution of petroleum accumulation and the saturated areas in the bakken members the volume of generated hydrocarbons was calculated and the extent of the highly saturated accumulation beyond the area of the high mature source was mapped furthermore it was demonstrated that petroleum accumulations beyond the high saturation zones have to be related to stratigraphic pinch outs lateral variability in permeability of the bakken members or smaller structural influences that were lost because of the resolution applied in the model

carbon isotope geochemistry of hydrocarbons in the cerro prieto geothermal field baja california norte mexico hydrocarbon abundances and stable isotopic compositions were measured in wells m5 m26 m35 and m102 which represent a range of depths 1270 2000 m and temperatures 275 330 degrees c in the field in order to simulate the production of the geothermal hydrocarbons gases were collected from the pyrolysis of lignite in the laboratory this lignite was obtained from a well which sampled rock strata which are identical to those occurring in the field but which have experienced much lower subsurface temperatures in both the well and the laboratory observations high temperature environments favored higher relative concentrations of methane ethane and benzene and generally higher delta 13c values in the individual hydrocarbons the best correlation between the laboratory and well data is obtained when laboratory produced gases from experiments conducted at lower 400 degrees c and higher 600 degrees c temperatures are mixed this improved correlation suggests that the wells are sampling hydrocarbons produced from a spectrum of depths and temperatures in the sediments

discriminating quarry blasts from earthquakes using coda waves abstract a new quarry blast earthquake discrimination method is presented based on the analysis of seismic coda waves quarry blasts and local earthquakes in the area encompassing the south central mojave desert and eastern transverse ranges were used to test this method we found that the coda decay rate q c 1 is significantly higher for quarry blasts than earthquakes for lower frequencies 1 5 and 3 hz for lapse time up to about 30 sec this result is attributed to the greater contribution of surface waves to quarry blasts due to the shallowness of their source depth the difference in q c 1 however disappears for lapse time greater than 30 sec for the same frequency range as well as for higher frequencies 6 and 12 hz for lapse time greater than 20 sec this suggests that the coda waves at the lapse time greater than these critical values are dominated by the same type of body waves probably s waves for both quarry blasts and earthquakes the power spectrum p 0 obtained after the correction for attenuation was compared between earthquakes and quarry blasts at the same stations and a significant difference was found in the spectral shape between these two data sets the curves of power spectrum p 0 versus frequency for quarry blasts decrease more sharply than for earthquakes at high frequencies indicating a lack of energy in high frequencies for quarry blasts as compared to earthquakes the different frequency dependence of power spectrum p 0 between quarry blasts and earthquakes is attributed to their different source properties and can be used for seismic discrimination of quarry blasts from earthquakes

excess methane in continental hydrothermal emissions is abiogenic thermogenic hydrocarbons entirely deriving from the thermal degradation of organic matter usually exhibit methane to ethane plus propane ratios smaller than 100 we present hydrocarbon distribution data of continental hydrothermal gases whose methane has been independently identified to derive from the abiogenic reduction of co2 we find that excess amounts of methane with respect to thermogenic hydrocarbon distributions are characteristic for the investigated gases a similar pattern is observed for well discharges whose temperatures are too high to support any microbially mediated methanogenesis these findings strongly suggest that abiogenic methane production in continental hydrothermal systems is a more widespread process than previously assumed the maximum contribution of such emissions to the modern atmospheric ch4 budget is estimated at 1

constraints on explosive sources with spall from near source waveforms spall the tensile failure of a material due to high stress loading has been observed in a number of contained and surface explosions the phenomenon results in a repartition of the initial spherical explosion energy source yielding a second energy source which is cylindrical and delayed in time recent spall models by day et al 1983 demanding conservation of momentum have shown the phenomenon to have little contribution to 20 sec surface waves these models are extended to include the effect of the process on near source seismograms the spall model is constrained by observations within the nonlinear regime of the source which bound the mass momentum and timing of the process comparison of these forward models with the inverse vertical point force source inferred from seismic recordings of a bermed surface explosion yields excellent agreement the spall model developed from the contained explosion cheat is used to create synthetic seismograms comparisons of these waveforms with those from a mueller murphy contained explosion indicate that the waveform contribution from spall is similar in size to the spherical explosion waveform the complete synthetic composed of the spall and explosion contribution compares favorably with observational data from the cheat experiment in both amplitude and energy distribution

paleoenvironmental changes in the japan sea during the last 85 000 years five distinct changes in the paleoenvironment of the japan sea within the last 85 000 years are revealed from the sedimentary record of a piston core recovered from the oki ridge changes in both surface and deepwater conditions are registered by changes in lithology calcium carbonate content organic carbon content oxygen and carbon isotope ratios and microfossil assemblages including calcareous nannoplankton diatoms radiolaria and foraminifera between 85 and 27 ka the warm tsushima current did not flow into the japan sea and cold surface water conditions prevailed environments at the seafloor fluctuated between dysaerobic to weakly oxic conditions between 27 and 20 ka freshwater input to the japan sea probably from the huang ho river in china stratified the water column and the severe anoxic conditions eliminated most benthic fauna between 20 and 10 ka the cold oyashio current flowed into the japan sea through the tsugaru strait reestablishing deepwater ventilation shallow water benthic assemblages of the north pacific ocean subsequently colonized the japan sea and occupied the vacant niches of the deep basins between 10 and 8 ka the foraminifer compensation level fcl gradually rose to a depth shallower than 1000 m and bottom conditions changed from dysaerobic to oxic at 10 ka the warm tsushima current started to flow into the japan sea through the tsushima strait to establish the modern oceanographic regime which has existed since 8 ka the eustatic sea level during the last glacial maximum was above the sill depths 130 m of the tsushima and tsugaru straits assuming that tectonic movements at these straits were negligible for the last 20 ka

spatial biome changes in southwestern japan since the last glacial maximum abstract data from published palynological studies in southwestern japan between 20 ka bp and the present were applied in a biomization procedure for japan the 20 biome maps obtained reveal a transition in biome from cool mixed forest to warm mixed broadleaved evergreen forest and their migration routes during the last glacial maximum southwestern japan was covered with cool mixed forest and the climate was cooler than present the warm mixed broadleaved evergreen forest was established in northern kyushu island and in the coastal areas of the sea of japan at 17 and 7 ka bp respectively there appears to have been a delay in its migration into the chugoku region caused by the environmental changes in the sea of japan before 8 ka bp the relatively weak flow of the tsushima warm current into the sea of japan created a climate resembling continental conditions and the winter temperatures were not high enough to permit the establishment of a warm mixed broadleaved evergreen forest after 8 ka bp warm mixed broadleaved evergreen forest spread into the chugoku region and reached higher altitudes 4 ka bp

hydrocarbon potential of the zechstein main dolomite upper permian in western poland relation to organic matter and facies characteristics abstract the zechstein main dolomite ca2 in the area between grotow platform and western part of the gorzow platform in western poland represents the 3rd order sequence of the polish zechstein the deposits are mainly the hst carbonate facies totally fifteen hst microfacies associations were identified and they represent the carbonate platform shallow subtidal supratidal deposits the platform slope upper lower slope deposits and the basin environments the deposition of the ca2 was controlled by the pre zechstein paleomorphology and the systems of tectonic dislocations on this background the geochemical results are presented and their source nature characterized in the context of the facial model of the ca2 the results of geochemical analyses indicate that most of samples collected in the study area contain the epigenetic hydrocarbons in the ca2 carbonates the toc values range from near zero to 5 2 wt and these of hydrocarbons contents reach up to 9 6 mg g rock despite such significant variability the average values are low and do not exceed 0 5 toc and 2 5 mg hc g rock all geochemical parameters indicate that the ca2 carbonates from the study area represent poor to fair oil prone source rocks with local good and or excellent hydrocarbon potential the macerals composition reveals predominance of the oil prone type ii kerogen in all studied microfacies in the kerogen composition organic mineral associations and solid bitumens prevail the organic matter from the ca2 was deposited under anoxic conditions in the hypersaline depositional environment the maturity indicators vitrinite reflectance r o temperature t max and biomarker parameters indicate that the maturity of organic matter corresponds to the final phase of the oil window and to the early phase of the gas window

a structural outline of the serra de tramuntana of mallorca balearic islands abstract the structural and stratigraphic aspects of the balearic islands are described by outlining the geology of the serra de tramuntana this range is part of the southeastern margin of the valencia trough and has the typical features of thrust tectonic areas a stratigraphic column a structural map and three cross sections show the main features of this range thrusts dip to the southeast and are arranged in an imbricate system with a transport direction to the nw the thrusts recorded involve upper paleozoic to middle miocene rocks imbricates bearing thin slices and duplexes developed where thin sequences with pronounced competency contrasts exist folds are also present they usually trend ne sw except in local areas where they are interpreted as being associated with oblique ramps fold axes plunge sub horizontally and folds face the northwest thrust displacements of up to 10 km are deduced from the existence of klippes and windows and shortening of around 50 is deduced from a comparison of deformed and restored cross sections the onset of the main contractional event is pre miocene probably late oligocene in age but major thrust emplacement occurred during the middle miocene the widespread occurrence of compression structures in the balearic islands developed from late oligocene to middle miocene put strong constraints on the models explaining the origin of both the valencia trough and the algerian basin the first must be considered at least in part as the balearic foreland basin and the second could be superimposed on the internal zone of the western mediterranean orogenic belt

bakken madison petroleum systems in the canadian williston basin part 2 molecular markers diagnostic of bakken and lodgepole source rocks abstract the uppermost devonian mississippian bakken formation black shale and the mississippian lodgepole formation carbonate represent two of the most important source rocks in the canadian williston basin quantitative analyses of both saturated and aromatic hydrocarbon fractions reveal significant differences in the relative distributions and absolute concentrations for a wide range of molecular markers between the extracts of the two source units among others the bakken shales are characterized by their high relative abundance of trimethyl aryl and diaryl isoprenoids likely derived from green sulfur bacteria chlorobiaceae in contrast the lodgepole carbonates at similar maturity levels display a c35 homohopane prominence and abundant benzohopanes ring d monoaromatic 8 14 secohopanes and a tetracyclic monoaromatic hydrocarbon the distinctive nature of molecular marker fingerprints diagnostic of the two source rocks is clearly related to their different organic inputs and depositional environments additionally the large difference in the absolute concentrations of these compounds observed in both source units may potentially lead to biased geochemical interpretations if strictly conventional saturate based biomarker approaches were used for oil oil and oil source correlation

geochemistry of artificially heated humic and sapropelic sediments i protokerogen experiments designed to simulate burial maturation have provided information on the geochemistry of classes of organic constituents in holocene sediments of different origin humic acids and kerogens isolated from laboratory heated laguna mormona baja california algal mat sapropelic facies and staten island california peaty deltaic soil humic facies were characterized by a variety of techniques including elemental analysis electron spin resonance programmed temperature pyrolysis vitrinite reflectance and stable isotope ratios the study shows that the generation of kerogen during burial is the net result of temperature time dependent synthetic and destructive reactions involving protokerogen and associated solvent extractable organic matter for the staten island sediment where the initial content of humic substances is high conversion of humic acid to gas prone kerogen is quantitatively the most significant maturation process for the laguna mormona algal mat where lipid content is high evidence suggests that some formation of oil prone kerogen may occur by cross linkage and binding of free lipids during diagenesis kerogen formation from humic acid in this sediment is minor

thermogenic hydrocarbons from the offshore calypso hydrothermal field bay of plenty new zealand hydrothermal gases from shallow seafloor vents in the bay of plenty new zealand contain co2 ch4 and the higher gaseous hydrocarbons up to i n c4h10 the gases are similar to those discharged at fumaroles on the nearby white island carbon isotope compositions for co2 fall between 3 4 and 5 5 pdb and reflect a shallow magmatic carbon source the 13c values of ch4 range from 24 6 to 28 9 pdb and the d values vary between 122 and 135 smow the ch4 isotope values and the presence of the higher hydrocarbon compounds such as c2h6 and c3h8 with 13c values near 20 pdb suggest hydrocarbon production by high temperature maturation of sedimentary organic matter and mixing 1 1 of the thermogenic ch4 with abiogenic ch4 long chained hydrocarbons occur in dredged samples close to the active vents their n alkane distribution has a high to moderate odd even predominance and an extensive hopane series indicative of higher land plant waxes and prokaryotic membranes in the source substantial amounts of unsubstituted polynuclear aromatic hydrocarbons pah mark the transition from aliphatic to aromatic dominated bitumens consistent with extensive source maturation resulting from thermal stress the bitumens are interpreted as pyrolysates derived from buried near coastal vegetation and terrestrial detritus under various thermal regimes mixed with immature seafloor organic matter

evolution of light hydrocarbon gases in subsurface processes constraints from chemical equilibrium abstract the behaviour of ch 4 c 2 h 6 and c 3 h 8 in subsurface processes such as magma intrusion volcanic gas discharge and natural gas generation have been examined from the viewpoint of chemical equilibrium it seems that equilibrium among these three hydrocarbons is attainable at about 200 c when a system at high temperatures is cooled re equilibration is continued until a low temperature is reached the rate at which re equilibration is achieved however steadily diminishes and below 200 c the reaction between the hydrocarbons stops and the gas composition at this time is frozen in and it remains unchanged in a metastable state for a long period of geological time natural gas compositions from various fields have shown that when a hydrocarbon system out of chemical equilibrium is heated it gradually approaches equilibrium above 150 c on the way towards equilibration compositions of thermogenic gases apparently temporarily show a thermodynamic equilibrium constant at a temperature that is higher than the real equilibrium temperature expected from the ambient temperature of the samples in contrast biogenic gases indicate a lower temperature in lower temperature regions kinetic effects probably control the gas composition the compositions are essentially subjected to genetic processes operating on the gases such as pyrolysis of organic material and bacterial activity and they fluctuate substantially examination of volcanic gases and pyrolysis experimental data however have suggested that the equilibration rate of these hydrocarbons is sluggish in comparison with that of reactive inorganic species such as h 2 s and so 2 the view presented in this study will be helpful in understanding the genetic processes that create oil and gas and the migration of these hydrocarbons and in interpreting the origins of magmatic gases

a two dimensional regional basin model of williston basin hydrocarbon systems institut francais du petrole s two dimensional model temispack is used to discuss the functioning of petroleum systems in the williston basin along a 330 km long section focusing on four regional source intervals ordovician yeoman formation lower devonian winnipegosis formation upper devonianulower mississippian bakken formation and mississippian lodgepole formation thermal history calibration against present temperature and source rock maturity profiles suggests that the williston basin can be divided into a region of constant heat flow of about 55 mw m2 away from the nesson anticline and a region of higher heat flow and enhanced thermal maturity in the vicinity of the nesson anticline original kinetic parameters used in the calibration were derived or each of the four source rocks from rock eval yield curves bakken overpressures are entirely due to oil generation not compaction disequilibrium very low bakken vertical permeabilities range from 0 01 to 0 001 nd are matched against observed overpressures whereas bakken porosities based on the model and confirmed by measurements are inferred to be also unusually low around 3 mature bakken shales do not seem to have reached hydraulic fractionation thresholds except perhaps locally in regions of extensional tectonic stress hydraulic fracturing cannot be viewed as a pervasive mechanism driving bakken oil expulsion our expulsion model confirms the high residual bakken oil saturations and explains the low residual s1 toc by the low bakken shale porosities approximately 85 of the oil generated in the bakken shales is predicted to have been expelled out of bakken strata which agrees with observed s1 toc trends madison group accumulations at the subcrop edge are found to be fed by lodgepole sourced oil only in particular by the rich middle lodgepole interval these accumulations probably result from a three dimensional migration pattern madison accumulations in the nesson anticline are found to be fed mostly by lodgepole sourced oil mixed with minor amounts of bakken sourced oil the vast majority of the expelled bakken oils are lost in the madison group at very low saturations this explains the low conventional oil resource associated with bakken sources by recent geochemical studies expulsion and migration occurred no earlier than the atest cretaceous paleocene in the yeoman and no earlier than the eocene in other source rocks consistent with temporal controls on oil migration flow models show no restriction to expulsion and migration of yeoman oil this suggests a potential undiscovered oil resource in ordovician and silurian strata of williston basin northeast of the nesson anticline

palaeovegetation and palaeoclimate in low latitude southern china during the last glacial maximum abstract the evolution of vegetation and climate changes in tropical regions during the last glacial maximum remains controversial a continuous high resolution terrestrial palynological data from 40 to 13 cal ka bp is recorded in sediments of huguangyan maar lake in southern china the biomization technique and pollen data are used to reconstruct the history of vegetation and climate changes during the last glacial maximum lgm the results suggest that the huguangyan area in the last glacial maximum was dominated by subtropical evergreen forest with some deciduous trees implying that the climate was drier and colder in southern china than at present grassland vegetation did not appear in this area a significant drop in temperature occurred at 18 5 cal ka bp and terminated at 15 5 cal ka bp and the annual mean temperature during the lgm was 2 3 c lower or even more than present this is in agreement with previous results from tropical low latitude regions

mixing of thermogenic natural gases in northern appalachian basin stable isotopic studies were undertaken to investigate the origin of 20 oil associated and non associated gases from western and central new york state in the northern appalachian basin gas wetness c2 c5 c1 c5 methane dgr13c and methane dgrd values range from 0 8 to 26 9 47 9 to 30 7 pmil and 305 to 143 pmil respectively corresponding ethane and propane dgr13c values range from 40 9 to 32 0 pmil and 34 9 to 27 9 pmil these data are interpreted to indicate a thermogenic origin with source rock maturities ranging from early mature equivalent vitrinite reflectance ro approximately 0 5 to post mature equivalent ro 2 0 inferred gas maturities generally in rease with increasing reservoir age from late to middle devonian marcellus and overlying rocks middle devonian to latest silurian oriskany onondaga akron silurian lockport herkimer medina to ordovician queenston and black river oil and gas in many late to middle devonian reservoirs may have migrated from interbedded organic rich shales in other reservoirs particularly those of ordovician and silurian age unusual isotopic reversals methane dgr13c ethane dgr13c suggest that gas generated locally from equivalent age rocks within the oil window mixed with post mature gas migrated from deeply buried sources to the south and southeast the post mature gas was probably sourced from middle to late ordovician shales regional migration of middle ordovician gas may have occurred along the middle ordovician knox unconformity gas was presumably channeled into overlying silurian and devonian reservoirs along faults and fractures

multiple origins of methane in the earth methane occurrences in the earth s crust are predominantly of biogenic origin i e their ultimate source is biologically formed organic matter methane can also form through inorganic reactions and is consequently termed abiogenic biogenic methanes can either form through bacterial or thermogenic processes bacterial processes follow a co2 reduction and or fermentation pathway the fermentation processes are quantitatively more important in recent fresh sediments and swamps methane formed by co2 reduction however is most common in older sediments and commercial gasfields temperature organic substrate and age may be the major factors controlling the relative importance of the two pathways stable isotope concentrations in thermogenic methanes seem to be controlled by the extent of conversion of organic matter the timing of gas expulsion and trapping the different character of methane in individual sedimentary basins may be a result of the geologic history geothermal methanes are most likely derived from pyrolysis of organic matter abiogenic methane occurs in hydrothermal vents and ophiolite complexes inorganic reactions either surficial or deep seated are the likely source of such methanes a uniform mantle origin of methane is not supported by the observed isotope variations in naturally occurring methanes

source parameter estimation for large bermed surface chemical explosions abstract near source accelerograms 0 2 to 2 0 km range were acquired from a series of bermed surface charges 0 075 to 1 65 kilotons detonated in alluvium at a test site near yuma arizona the areal extent of the explosion test beds radii from 18 to 54 m affords the unique opportunity to study wave propagation from and source parameters of large surface explosions at near source ranges p and sv rayleigh phases are identified using particle motions rayleigh waves at an intermediate range transition to a combination of higher mode and fundamental mode rayleigh waves at the farthest range the power law decay rates for body waves radial at r 1 8 and vertical at r 1 4 and surface waves radial at r 1 0 and vertical at r 0 8 are further indication of complex propagation effects in the shallow alluvial geology as a result of this complexity and the two orders of magnitude range of explosive yields available seismic source parameters are obtained with full waveform spectral ratios source corner frequency is proportional to the radius of the explosion test beds and long period level relative moment scales linearly with yield spectral ratio yield estimates using smaller explosions as standard or calibration events gave absolute yield estimates within 6 to 35 of the true yield with a linear scaling law the precision of individual yield estimates is reflected by multiplicative errors of 1 11 to 1 17 full waveform spectral ratio corner frequency estimates compare favorably with reglonal p wave corner frequencies and validate the use of the spectral ratio technique for near source seismic data

spectral evidence for source multiplicity in explosions application to regional discrimination of earthquakes and explosions abstract spectral and cepstral analysis were performed on regional array noress recordings of mining explosions in scandinavia and russia in order to detect the effects of delayed explosions or ripple firing commonly used in mine blasting practice noress array stacked spectra corrected for instrument and noise were computed in windows on pn pg sn and lg waves from the mine blasts by averaging individual channel spectra frequency by frequency across the array for comparison spectra were also computed for six western norway earthquakes located near the blasjo and titania norwegian mines also stack spectra of p coda sn and lg were computed using norsar seismograms for presumed peaceful nuclear explosions pnes located at near regional distances 10 in western russia the norsar spectra were determined in the same manner as the noress spectra except that an individual source correction was applied to the spectra comparison of western norway mine blast spectra and nearby earthquakes shows that the earthquake pn spectra are peaked in the 8 to 16 hz band with little energy below 6 hz whereas the explosion spectra have flatter spectra from 3 to 16 hz this difference in the pn spectra may be caused by the earthquakes occurring at greater depths than the explosions differences in the near source media or source mechanism effects in the earthquake spectra the main difference between earthquake and explosion spectra is that the explosion spectra exhibit marked scalloping or modulation patterns not observed in the earthquake spectra the modulation patterns are identical in spectra of all phases indicating that they are caused by multiple shot sequences or ripple firing simulated multiple source spectra determined using the noress seismograms for one of the western norway earthquakes resulted in spectra that resembled many of the explosion modulation patterns based on the simulation studies and cepstral analysis of the spectra the mine explosions appear to be composed of two to three separate explosions delayed by between 80 to 150 msec moreover the norsar spectra of pnes indicate that these signals are also produced by multiple explosions although they have larger delay times of between 0 9 to 1 5 sec these results show that spectral modulations in seismogram spectra of economic explosions including mine explosions and nuclear explosions fired for peaceful economic purposes can be used to distinguish them from earthquakes and nuclear explosion weapons tests

mississippian bakken and equivalent formations as source rocks in the western canadian basin abstract the organic rich bakken formation of mississippian age has previously been identified as the source rock for mississippian reservoired oils in the williston basin north dakota examination of c15 hydrocarbon data including biomarker distributions steranes triterpanes and diterpanes and stable carbon isotope ratios of bakken formation core samples from williston basin and those of equivalent formations from western canadian basin alberta reveals similar types of extractable organic matter stable carbon isotope and biomarker data support strong positive correlations between the bakken formation core samples and mississippian oils from both basins in addition a positive correlation is found between bakken core samples and lower cretaceous heavy oil deposits from athabasca cold lake and peace river areas in alberta thus the mississippian bakken and equivalent formations are also important source rocks in the western canadian basin

near source characterization of the seismic wavefield radiated from quarry blasts summary a series of controlled seismic experiments performed in a limestone quarry demonstrate the utility of high precision electronic detonators in studying source characteristics of multiple explosive arrays at near source ranges 80 130m where source dimensions are on the same order as source receiver distances the influence of the difference in travel path length among individual explosions on the seismograms is significant focusing of the seismic energy is observed as a function of station location with respect to the source array and is attributed to the extended source length 68 94 m and firing time of the source 380 544 ms we examine two methods for modelling ripple fired explosions at near source ranges using the principles of superpositioning the first method is based primarily on acquisition of an adequate single shot signal and requires well constrained shot times amplitude variations which result from travel path differences are not modelled which restricts use of this technique for purposes of blast vibration reduction to larger distances 2 3 source dimensions where the spatial finiteness effects of the source begin to diminish for near source distances 2 source dimensions we successfully model multiple source seismograms by convolving a synthetic seismic source signal for a single explosion with individual half space green s functions calculated for each explosion in the array our single source model for a cylindrically shaped single charge borehole length of 17 5 m and diameter of 90 mm of 68 kg consists of a modified mueller murphy approximation which utilizes source parameter estimates taken from chemical explosion study results model parameters include a final cavity radius of 0 25 m and an elastic radius of 18 m the final model is obtained by convolving the simulated single source time series with half space green s functions calculated for several source depths and superposed to approximate the spatial extent of the borehole the relative amplitude and phase characteristics of the observed single source signal at the same distance 80 6 m are reproduced by this model multiple source synthetic seismograms contain individual green s functions for each source receiver distance but utilize identical sources for the explosive array focusing effects are shown to be due to the effect of propagation path differences between individual explosions in agreement with the results of anderson stump 1989 in simulating multiple source seismograms good fits to the measured production shot amplitude spectra are obtained with the synthetic spectra spectral peaks are well matched due to precision of the firing times which were controlled by electronic detonators our example of delay time variances for 32 ms production shot appendix argues for better constraint of firing times for contolled seismic experiments such constraint requires a 1 per cent error or less in cap firing times which can be realized by the use of firing systems with an order of magnitude increase in precision compared to pyrotechnic detonators

geochemistry of low molecular weight hydrocarbons in hydrothermal fluids from middle valley northern juan de fuca ridge abstract hydrothermal vent fluids from middle valley a sediment covered vent field located on the northern juan de fuca ridge were sampled in july 2000 eight different vents with exit temperatures of 186 281 c were sampled from two areas of venting the dead dog and odp mound fields fluids from the dead dog field are characterized by higher concentrations of nh3 and organic compounds c1 c4 alkanes ethene propene benzene and toluene compared with fluids from the odp mound field the odp mound fluids however are characterized by higher c1 c2 c3 and benzene toluene ratios than those from the dead dog field the aqueous organic compounds in these fluids have been derived from both bacterial processes methanogenesis in low temperature regions during recharge as well as from thermogenic processes in higher temperature portions of the subsurface reaction zone as the sediments undergo hydrothermal alteration carbon dioxide and hydrocarbons are released to solution as organic matter degrades via a stepwise oxidation process compositional and isotopic differences in the aqueous hydrocarbons indicate that maximum subsurface temperatures at the odp mound are greater than those at the dead dog field maximum subsurface temperatures were calculated assuming that thermodynamic equilibrium is attained between alkenes and alkanes benzene and toluene and carbon dioxide and methane the calculated temperatures for alkene alkane equilibrium are consistent with differences in the dissolved cl concentrations in fluids from the two fields and confirm that subsurface temperatures at the odp mound are hotter than those at the dead dog field temperatures calculated assuming benzene toluene equilibrium and carbon dioxide methane equilibrium are similar to observed exit temperatures and do not record the hottest subsurface conditions the difference in subsurface temperatures estimated using organic geochemical thermometers reflects subsurface cooling processes via mixing of a hot low salinity vapor with a cooler seawater salinity fluid because of the disparate temperature dependence of alkene alkane and benzene toluene equilibria the mixed fluid records both the high and low temperature equilibrium conditions these calculations indicate that vapor rich fluids are presently being formed in the crust beneath the odp mound yet do not reach the surface due to mixing with the lower temperature fluids

the impact of severe biodegradation on the molecular and stable c h n s isotopic compositions of oils in the alberta basin canada abstract although the effects of biodegradation on the composition and physical properties of crude oil have been well studied effects of in reservoir petroleum biodegradation on molecular and isotopic compositions of crude oils are not yet clearly understood the alberta basin in western canada is one of the world s largest petroleum accumulations and constitutes an ideal example of a natural suite of sequentially biodegraded oils the basin hosts moderately to severely biodegraded petroleum regionally distributed and in single more or less continuous oil columns in this study a series of oil samples from the alberta heavy oil and oil sands provinces with varying degrees of biodegradation were analyzed to assess the impact of progressive biodegradation on the molecular and c h n and s isotopic compositions of oils the results of the molecular characterization of the hydrocarbon fraction of the studied oils show that the oils have suffered biodegradation levels from 2 to 10 toward the alberta saskatchewan border on the peters and moldowan scale of biodegradation abbreviated pm 2 to pm 10 and from tens to hundreds on the manco scale within single reservoirs increasing biodegradation was observed from top to bottom of the oil columns at all sites studied the whole oil stable isotopic compositions of the samples varied in the ranges 13 c 31 2 to 29 0 2 h 147 to 133 15 n 0 3 4 7 and 34 s 0 4 6 4 the maximum differences between values of samples within single oil columns were 13 c 1 4 2 h 7 15 n 1 7 and 34 s 1 0 regional variations in the isotopic compositions of oil samples from different wells averaged values from top to bottom were 1 2 for 13 c 12 for 2 h 4 1 for 15 n and 5 5 for 34 s and hence generally significantly larger variations were seen than variations observed within single oil columns especially for n and s it appears that even severe levels of biodegradation do not cause observable systematic variations in carbon nitrogen or sulfur isotope composition of whole oils this indicates that sulfur and nitrogen isotopic compositions may be used in very degraded oils as indicators for oil charge from different source rock facies

abiogenic methanogenesis in crystalline rocks isotopically anomalous ch4 rich gas deposits are found in mining sites on both the canadian and fennoscandian shields with 13cch4 values from 22 4 to 48 5 and dch4 values from 133 to 372 these methane deposits cannot be accounted for by conventional processes of bacterial or thermogenic methanogenesis compositionally the gases are similar to other ch4 rich gas occurrences found in canadian and fennoscandian shield rocks sherwood lollar et al 1993 however the isotopically anomalous gases of this study are characterized by unexpectedly high concentrations of h2 gas ranging from several volume percent up to 30 vol the h2 gases are consistently depleted in the heavy isotope with dh2 values of 619 to 659 3h 4he ratios in the range of 0 4 10 8 to 4 4 sx 10 8 indicate that there is no resolvable component of mantle derived he in these deposits based on these results a mantle derived source for the c bearing gases is unlikely several lines of evidence support an alternative abiogenic origin for the gases from sudbury canada and juuka and pori finland the d depleted h2 gas and calculated d ch4 h2 equilibration temperatures of 110 170 c at all three sites are in good agreement with results obtained for abiogenically produced ch4 and h2 in ophiolite sequences in oman and the philippines serpentinization and the hydration of ultramafic rocks are the proposed mechanisms for ch4 and h2 production in these ophiolite sequences the widespread occurrence of serpentinized and altered ultramafic rocks at juuka and at a number of other sites in both canada and finland implies that similar mechanisms may be involved in gas production at at least three sites on the shields the origin of the gases at the remaining shield sites is discussed alternative hypothesis include 1 production of the rest of the shield gases by mixing between abiogenic endmembers and bacterially generated hydrocarbon gas such as identified elsewhere on the canadian and fennoscandian shields sherwood lollar et al 1993 and 2 production of a series of isotopically distinct abiogenic ch4 endmembers at each site due to variability in the isotopic composition of available carbon sources we cannot conclusively distinguish between the alternative scenarios based on existing data however the evidence for an abiogenic ch4 endmember at at least three sites emphasizes the need for substantial revision of current theories of methanogenesis abiogenic processes of ch4 production may be considerably more widespread than previously anticipated

geogenic and atmospheric sources for volatile organic compounds in fumarolic emissions from mt etna and vulcano island sicily italy 1 in this paper fluid source s and processes controlling the chemical composition of volatile organic compounds vocs in gas discharges from mt etna and vulcano island sicily italy were investigated the main composition of the etnean and volcano gas emissions is produced by mixing to various degrees of magmatic and hydrothermal components vocs are dominated by alkanes alkenes and aromatics with minor though significant concentrations of o s and cl f substituted compounds the main mechanism for the production of alkanes is likely related to pyrolysis of organic matter bearing sediments that interact with the ascending magmatic fluids alkanes are then converted to alkene and aromatic compounds via catalytic reactions dehydrogenation and dehydroaromatization respectively nevertheless an abiogenic origin for the light hydrocarbons cannot be ruled out oxidative processes of hydrocarbons at relatively high temperatures and oxidizing conditions typical of these volcanic hydrothermal fluids may explain the production of alcohols esters aldehydes as well as o and s bearing heterocycles by comparing the concentrations of hydrochlorofluorocarbons hcfcs in the fumarolic discharges with respect to those of background air it is possible to highlight that they have a geogenic origin likely due to halogenation of both methane and alkenes finally chlorofluorocarbon cfc abundances appear to be consistent with background air although the strong air contamination that affects the mt etna fumaroles may mask a possible geogenic contribution for these compounds on the other hand no cfcs were detected in the vulcano gases which are characterized by low air contribution nevertheless a geogenic source for these compounds cannot be excluded on the basis of the present data

high frequency seismic observations and models of chemical explosions implications for the discrimination of ripple fired mining blasts discrimination of large chemical explosions e g mining blasts from possible clandestine nuclear tests e g decoupled explosions is a significant issue for seismic verification unless discrimination is possible the numerous mining blasts within the ussr would give ample opportunity for concealing a clandestine test evernden et al 1986 advocate high frequencies as a means to detect these clandestine tests however mining blasts must still give a unique signature for their discrimination specific conditions are also necessary for high frequency verification low attenuation and quiet seismic stations are among the most important in this study we address these problems under conditions representing a best case scenerio during the summer of 1985 lawrence livermore national laboratory llnl deployed a regional array and high frequency seismic station near rson red lake ontario canada to study regional seismic signals at a low noise site with excellent propagation characteristics the continental shield one objective was to evaluate the performance of regional seismic arrays and high frequency stations in this geological environment using high frequency data from mining blasts within the mesabi iron range in northern minnesota distance of 380 km we also observed the high frequency pn phase of ripple fired blasts modeled their source properties and evaluated a possible discriminant for chemical explosions this study suggests the existence of a distinctive signature for large chemical explosions strong high frequency spectral peaks in the p spectra introduced by delay shooting or ripple firing its application depends however on a frequency band extending to at least 35 hz at regional distances reasonably uniform delay times in the blast pattern predictably quiet seismic sites and minimal path attenuation for high frequencies at 380 km we observe good propagation to 30 hz at 50 hz the evidence suggests severe attenuation or scattering which is consistent with a total q between 1500 and 2500 attenuation estimates assuming a simple source behavior e g f 2 or f 3 at high frequencies for mining explosions would give incorrect values of q unless corrected for the blast pattern these attenuations will limit the value of high frequencies for the detection of small decoupled explosions at regional distances

circum arctic petroleum systems identified using decision tree chemometrics source and age related biomarker and isotopic data were measured for more than 1000 crude oil samples from wells and seeps collected above approximately 55n latitude a unique multitiered chemometric multivariate statistical decision tree was created that allowed automated classification of 31 genetically distinct circum arctic oil families based on a training set of 622 oil samples the method which we call decision tree chemometrics uses principal components analysis and multiple tiers of k nearest neighbor and simca soft independent modeling of class analogy models to classify and assign confidence limits for newly acquired oil samples and source rock extracts geochemical data for each oil sample were also used to infer the age lithology organic matter input depositional environment and identity of its source rock these results demonstrate the value of large petroleum databases where all samples were analyzed using the same procedures and instrumentation

petroleum source rock evaluation of the alum and dictyonema shales upper cambrian lower ordovician in the baltic basin and podlasie depression eastern poland we present geochemical characteristics of the lower palaeozoic shales deposited in the baltic basin and podlasie depression in the study area this strata are represented by the upper cambrian lower ordovician alum shale recognized in southern scandinavia and polish offshore and a equivalent the lower tremadocian dictyonema shale from the northern estonia and the podlasie depression in poland geochemical analyses reveal that the alum shale and dictyonema shale present high contents of organic carbon these deposits have the best source quality among the lower palaeozoic strata and they are the best source rocks in the baltic region the bituminous shales complex has toc contents up to ca 22 wt the analysed rocks contain low sulphur oil prone type ii kerogen deposited in anoxic or sub oxic conditions the maturity of the alum and dictyonema shales changes gradually from the east and north east to the west and south west i e in the direction of the tornquist teisseyre zone samples located in the seashore of estonia and in the podlasie region are immature and in the initial phase of oil window the mature shales were found in the central offshore part of the polish baltic basin and the late mature and overmature are located in the western part of the baltic basin the alum and dictyonema shales are characterized by a high grade of radioactive elements especially uranium the enrichment has a syngenetic or early diagenetic origin the measured content of uranium reached up to 750 ppm and thorium up to 37 ppm

unusual crude oils in the canadian williston basin southeastern saskatchewan abstract the jedburgh well location 16 14 27 8w2 was drilled on a small salt dissolution structure in the williston basin the well lies near the cussed creek structure a complex feature involving both phanerozoic faults that offset the precambrian basement and the dissolution edge of the middle devonian prairie formation halite the chemical compositions of crude oils recovered from cores of devonian strata in this well are unique in the williston basin and unusual in a global perspective because they contain significant quantities of olefins with the n c 17 alk 1 ene alkane ratio ranging from 0 28 to 0 72 the gross chemical compositions and distributions of aliphatic biomarkers aromatic hydrocarbons and pyrrolic nitrogen compounds in the oils indicate that they were generated by high temperature short term pyrolysis of thermally immature organic matter their composition indicates that they were not generated in situ but accumulated in the jedburgh well after lateral migration from areas that were influenced by post devonian magmatic intrusions the inferred migration distance 10 km suggests that such intrusions occur within the cussed creek structure

classification of local and regional events in central europe based on estimates of s wave spectral variance summary the vogtland region in the border region of germany and the czech republic is of special interest for the identification of seismic events on a local and regional scale since both earthquakes and explosions occur frequently in the same area and thus are relevant for discrimination research for verification of the comprehensive nuclear test ban treaty previous research on event discrimination using spectral decay and variance from data recorded by the geress array indicated that spectral variance determined for the s phase for the seismic events in the vogtland region seems to be the most promising parameter for event discrimination because this parameter provides for almost complete separation of the earthquake and explosion populations almost the entire set of vogtland events used in this research and more than 3000 local events detected in germany in 1998 and 1999 were analysed to determine spectral slopes and variance for the p and s wave windows from stacked spectra of recordings at the geress array the results suggest that small values for the spectral variance are associated not only with earthquakes in the vogtland region but also with earthquakes in other parts of germany and neighbouring countries while mining blasts show larger spectral variance values mininginduced events yield a wide range of values for example in the lubin area a threshold based identification scheme was applied almost all events classified as earthquakes are found in seismically active regions while the earthquakes are uniformly distributed throughout the day events classified as explosions correlate with normal working hours which is when blasting is done in germany in this study spectral variance provides good event discrimination for events in other parts of germany not only for the vogtland region showing that this identification parameter may be transported to other geological regions

frequency domain scaling of single fired mining explosions with different confinements and explosive weights detonated in porphyry granite abstract a series of single fired simultaneously detonated explosions were conducted in an arizona copper mine the explosions spanned yields from 773 to 6182 kg and were all detonated in an approximately 100 by 100 m area the individual explosions were also detonated under three different emplacement conditions including at the free face of the mine under normal burden distance from the free face resulting in failure and movement of the free face at twice normal burden with free surface failure and cratering and at twice normal depth which fully contained the explosions the purpose of this analysis was to investigate the relationship between explosive weight and confinement on the amplitude and frequency content of seismic waves empirical scaling relations for the different shots in this test series were developed using common receivers in order to quantify the effects of explosive weight and confinement spectral ratios between observations at the same stations for the different explosions were used to remove common instrument and propagation path effects from the data set empirical scaling functions estimated from data at ranges from a few hundred meters to several tens of kilometers produce similar results the mueller murphy source model has been used to assess the effects of explosion depth and material in which the explosions are detonated material properties were measured for the porphyry granite at the mine and were used in forward models for the yield scaling of the fully contained explosions the forward models replicate the empirical scaling functions at low frequency

integrated stress determination by joint inversion of hydraulic tests and focal mechanisms an inversion method based on a genetic algorithm is proposed for interpreting jointly various kinds of stress data in order to overcome the limitation in number and quality of each data set the method has been applied to results from hydraulic tests in boreholes and to focal mechanisms of induced seismicity observed within the same depth interval the regional stress field is described by two symmetrical tensors the first one represents the stress at a given depth and the second one the vertical stress gradient results indicate that one of the principal directions is vertical they are consistent with all but one of the hydraulic tests considered in the inversion and with about 70 of the focal mechanisms this inversion confirms previous results suggesting that for the scale of these induced microseismic events the regional stress field cannot be determined solely from an inversion of the fault plane solutions

prior calcite precipitation and source mixing process influence sr ca ba ca and 87sr 86sr of a stalagmite developed in southwestern japan during 18 0 4 5ka abstract we measured sr ca ba ca 87 sr 86 sr ratios 18 o and 13 c values in a stalagmite which developed 18 0 4 5 thousand years ago ka in southwestern japan dripwater and two major bedrocks limestone and andesite in the locality were also studied the 87 sr 86 sr ratios of the stalagmite are relatively homogeneous 0 706852 0 706921 suggesting a steady source mixing ratio of 40 from high 87 sr 86 sr limestone and 60 from low 87 sr 86 sr andesite the stalagmite sr ca and ba ca ratios were higher than the ratio expected from the dissolved fraction of limestone and andesite the covariance among sr ca ba ca and 13 c profiles suggests a significant role of prior calcite precipitation pcp i e carbonate precipitation from infiltrating water before the water drips on a stalagmite the relationships among stalagmite sr ca ba ca ratios and 13 c values are consistent with the rayleigh type fractionation model supporting that pcp results in successive enrichment of sr ba and 13 c in the aqueous phase and the resulting stalagmite the degree of pcp calculated for the stalagmite is highly variable from 0 to 85 and generally decreased from the last glacial period to the middle holocene the large degree of pcp observed during 18 15 ka implies a relatively dry climate during this period which is consistent with weak monsoon intensity inferred by the 18 o values the 87 sr 86 sr ratios of the stalagmite show a slight decrease through the entire period the increase in the andesite derived fraction with relatively high 87 sr 86 sr may result from accelerated silicate weathering in the epikarst with increasing temperature humidity and soil p co 2

hydrothermal hydrocarbon gases 1 genesis and geothermometry various sources for hydrothermal ch4 have been proposed over the years while c isotope studies have narrowed the possibilities enough higher hydrocarbon gas data now exist both to supplement the isotopic data and to permit additional deductions regarding origins comparison of typical c1 c6 data for gases of various origins from sedimentary and crystalline rocks and hydrothermal systems reveals certain characteristics apart from isotopic differences hydrothermal hydrocarbons differ from sedimentary hydrocarbons mainly in possessing tendencies towards a relative excess of ch4 higher normal iso ratios for butane and pentane and relatively high amounts of c6 gases despite these differences consideration of the evidence indicates that hydrothermal hydrocarbon gases in most cases originate like sedimentary basin gases by thermal degradation of organic matter in the relatively shallow subsurface the principal characteristic of these hydrothermal gases excess ch4 appears to have a geothermometric function the following empirical relationship has been derived t c 57 8 log ch4 c2h6 96 8 which fits moderately well a range of geothermal fields worldwide this gas geothermometer may be particularly applicable during geothermal exploration in areas where there is little direct knowledge of subsurface conditions

hydrocarbon potential of the zechstein main dolomite in the western part of the wielkopolska platform sw poland new sedimentological and geochemical data abstract the results of identification of facies and microfacies of highstand systems tract hst deposits in the zechstein main dolomite ca2 are presented followed by a critical analysis of the existing views on the paleogeography and facies architecture of the wielkopolska platform eastern part of the fore sudetic monocline sw poland the authors discuss and question the existence in zones that have been treated as basinal flat in the analysed area and an extensive platform margin ooidal barrier in general the facies architecture of the study area resembles the block built of the paleozoic basement on this background analytical geochemical results are presented and their source nature characterized in the context of a new revised model of the ca2 basin paleogeography a new facies classification of carbonates which has not been applied for the polish part of the ca2 basin yet was presented the geochemical characteristic of ca2 rocks indicates that good oil prone source rocks are present only locally and are connected with calcisiltites and dolomudstones of facies ii and dolobindstones of facies iv these facies are mainly present in the slope and toe of slope zones the microbial algal facies abundant in the carbonate platform have a weaker residual potential however the thermal maturity stays within the entire range of the oil window the rocks should be re labeled as good source rocks the presence of oil prone kerogen type ii and locally even type i makes the ca2 beds in this part of the wielkopolska platform a very efficient source rock the character of which is confirmed by numerous hydrocarbon accumulations related to the course of tectonic zones and morphology of the basement the proposed characteristic of source rocks in the new paleogeographic facies system enables their better petroleum evaluation and shall enable future prospecting of the perspective zones

carbon isotope composition of marine crude oils 1 a histogram of isotope 13 c values of 621 post ordovician marine oils shows a trimodal distribution within this distribution four groups of oils can be recognized on the basis of isotope 13 c values in conjunction with pristane phytane ratios and sulfur contents oils with isotope 13 c values of 32 0 to 28 0 o oo are mainly marine shale oils older than oligocene oils with isotope 13 c values of 28 0 to 23 5 o oo are mainly deltaic oils of varying geologic age or mesozoic carbonate oils and oils with isotope 13 c values heavier than 23 5 o oo are mainly marine shale oils of miocene age the isotope 13 c variation among oil groups is explained primarily by different factors that control the fractionation of carbon isotopes during primary production of rganic carbon miocene and younger marine shale oils are isotopically heavier than older marine shale oils because of decreased atmospheric co 2 concentration since 25 ma which has resulted in decreased isotope fractionation by marine plankton during photosynthesis deltaic oils are mostly derived from terrestrial organic matter and their isotope 13 c values reflect the time invariant average isotope 13 c value of land plant carbon at about 25 o oo mesozoic carbonate oils are isotopically heavy due mainly to salinity and temperature effects during primary production in restricted environments from which terrestrial organic matter is excluded processes that occur after oil generation generally have smaller effects on isotope 13 c values of oils as a result isotope 13 c val es of oils are useful for determining oil oil and oil source rock relationships and in conjunction with other geochemical properties can indicate the possible age and depositional environment of source rocks

induced seismicity around the tous new dam spain summary induced seismicity around the tous new dam located 45 km southwest of valencia spain is studied from a detailed analysis of seismic data from a 16 month period starting in 1999 january recorded by the tous new dam seismic network tdsn which comprises a threecomponent station located in the dam and six vertical component outstations within 25 km of the dam on the basis of the spatial 2d 3d and temporal distribution of this seismicity we have found 24 microearthquakes of magnitudes 0 4 3 8 most of which appear correlated in time and space with changes in the water level in the tous new dam reservoir an initial group of earthquakes all within 12 km or less of the reservoir occurred over roughly 1 yr starting in mid 1999 while the water level was at its maximum continuing during draining in late 1999 and subsequent refilling in early 2000 thereafter seismicity was more widespread reaching up to 40 km from the dam and with the greatest frequency of occurrence coinciding with the rapid draining of the reservoir in mid 2000 the few focal mechanisms able to be found are normal or strike slip in general it is clear that a relationship exists between reservoir water level which probably modifies the pre existing tectonic stress field and pore fluid pressures but no specific mechanism for the induced seismicity has yet been identified

further evaluation of the re os geochronometer in organic rich sedimentary rocks a test of hydrocarbon maturation effects in the exshaw formation western canada sedimentary basin abstract re os isotopic analyses of a single organic rich sedimentary rock unit ors of known depositional age and at three levels of regional hydrocarbon maturity show that hydrocarbon maturation does not affect the ability the 187re 187os chronometer to yield a depositional age for such rocks we present re os isotope analyses from the late devonian exshaw formation in the subsurface of the western canada sedimentary basin alberta and obtain a re os isochron age of 358 10 ma 2 model 3 1 666 10 11 a 1 for samples ranging from hydrocarbon immature to overmature this age is within uncertainty of the established absolute age for the exshaw formation hydrocarbon immature and mature plus overmature samples show no significant age differences if regressed individually indicating that hydrocarbon maturation did not greatly disturb the re os isotope system in the exshaw formation as such we propose that the re os geochronometer may be used as a reliable tool for measuring the depositional ages of ors regardless of their level of hydrocarbon maturity we find that minimizing natural variation in the initial 187os 188os ratio is more important than avoiding hydrocarbon maturation in obtaining precise re os ages in particular the exshaw formation appears to contain a nonhydrogenous component of unradiogenic os in addition to the hydrogenous os load a subset of exshaw formation samples with 5 total organic carbon toc which should best reflect the hydrogenous os load alone yields a very well fitted isochron having a depositional age of 358 9 ma 2 1 666 10 11 a 1 with an initial 187os 188os ratio of 0 59 0 05 model 3 mean square of weighted deviates mswd 1 8 the initial 187os 188os ratio of this regression may provide an estimate of the os isotopic composition of local seawater at the time of deposition

carbon isotope composition of lower palaeozoic kerogen effects of maturation abstract the carbon isotope composition of type i kerogen from a marine organic rich black shale deposit of late cambrian age the alum shale formation of southern scandinavia varies from 28 to 30 pdb the thermal maturity is rated by hi oi index t max pi and vitrinite reflectance values and published conodont alteration data the results range from immature conditions with regard to oil generation in central sweden to overmature and submetamorphic conditions in southern sweden denmark and norway in the immature areas the shale is found to be extremely hydrogen rich and oil prone hydrocarbon potential up to 85 kg per ton rock the observed 13 variations are not correlated with maturity it is therefore concluded that thermal maturation processes have no influence on the isotopic composition of a purely marine kerogen the observed range in lower palaeozoic 13 kerogen values 27 to 31 is in accordance with published results from other sedimentary basins

baogutu an example of reduced porphyry cu deposit in western junggar abstract classic oxidized porphyry copper deposits opcd are characterized by high tonnage and elevated f o 2 and contain highly oxidized minerals including primary anhydrite and hematite in contrast the baogutu deposit contains abundant hypogene pyrrhotite and methane rich fluid inclusions characteristic of lower tonnage reduced porphyry copper deposits rpcd mineral paragenesis and mineral chemistry studies reveal two mineralization periods magmatic and hydrothermal with the hydrothermal period further subdivided into three paragenetic stages including ca na alteration potassic alteration and propylitization locally overlapped by phyllic alteration several independent geothermometers indicate that the temperatures of the magma potassic and propylitization alteration are estimated to be 600 900 c 200 400 c and 200 300 c respectively multiple indicators including mineral assemblages apatite so 3 content whole rock fe 2 o 3 feo ratios and fluid compositions indicate the f o 2 of the magma and hydrothermal fluid to be nno and nno nno 2 respectively hydrothermal fluids associated with primary biotite yield log f h 2 o f hcl fluids values of 4 8 6 2 for diorite and 4 1 4 5 for granodiorite porphyry the log f s2 of the magmatic and potassic alteration are estimated to be 0 7 to 3 0 and 5 5 to 11 0 respectively based on pyrrhotite and sulfide assemblages mineral assemblage and hessite composition suggest the log f te2 of the potassic alteration is 8 5 to 14 5 the low tonnage baogutu deposit displays significantly lower f o 2 than opcds nno 2 and on this basis could be classified as a rpcd other physicochemical conditions including t f s2 log f h2o f hcl fluid do not show obvious differences to those of opcds we deduce that the low f o 2 of baogutu metallogenic granitoids and aqueous fluids likely produced the unusual pyrrhotite arsenopyrite mineral assemblage and the nacl h 2 o ch 4 co 2 ore forming fluids and small tonnage typical of rpcds previous obtained fluid inclusion h o isotope data and sulfide s pb isotope data suggest the methane rich ore forming fluids were derived from deep mantle source with little contamination from sedimentary components however detailed studies are needed to clarify the origin of the ch 4

oil families in mannville group reservoirs of southwestern alberta western canada sedimentary basin abstract lower cretaceous oils in southern alberta have been assessed using column chromatography sulphur analysis gas chromatography gc and gas chromatography mass spectrometry gc ms these oils can be divided into four oil families e q eq and f on the basis of biomarker characteristics family e oils are characterized by low pristane phytane ratios and a c 35 homohopane prominence family q oils are identified by the presence of so called q compounds q r ratio 0 5 and have high c 27 diasterane to regular sterane ratios family eq oils are a mixture of family e and family q oils with biomarker characteristics intermediate between these two families and low abundance of q compounds q r ratio 1 2 and no c 35 homohopane prominence oil source rock correlation to available source rock data suggest that family e oils are derived from the upper devonian mississippian exshaw formation and family q oils correlate to the lower cretaceous ostracode zone family f oils are likely derived from shales of the upper jurassic rierdon formation however additional geochemistry data from this potential source rock are required to confirm this interpretation

the relationship between microseismicity and high pore pressures during hydraulic stimulation experiments in low permeability granitic rocks several hundred microearthquakes with local magnitudes ranging between 4 and 2 were recorded during hydraulic stimulation experiments at the hot dry rock demonstration site fenton hill new mexico these events are probably caused by shear failure induced by high pore fluid pressures since the event locations seem to cluster in a narrow band near the hydraulic fracture we were able to use micro seismic techniques to locate the hydraulic fracture and monitor its growth we calculate the minimum pore pressure increase necessary to induce rock failure using a simple model of slippage on preexisting fractures by comparing a pore pressure distribution calculated using a one dimensional diffusion model with the distribution of event foci we demonstrate that high pore pressures are a probable cause for these microearthquakes stress drops for these microearthquakes calculated from spectral parameters increased by a factor of 3 during the course of the experiment the stress drop increase correlates with a migration of seismic activity away from the injection well bore which suggests relatively low in situ shear stresses near the well bore caused by strain release in this region during previous pressurizations

spectral characteristics of regional phases recorded at noress abstract the spectral characteristics of pn and lg are studied for regional events recorded at the noress array in norway the emphasis is on the potential value of spectral ratios for identifying events as earthquake chemical explosions and nuclear explosions the events studied include a suite of explosions from the titania mine in southwest norway a suite of events of unknown source type from a site offshore about 90 km from this mine suites of explosions from several mines in the soviet union about 1000 km from noress events from several locations along the 90 azimuth from noress an apparent earthquake in the north atlantic and a nuclear explosion pne at a range of 1560 km the event identification issues addressed are as follows 1 can earthquakes and explosions be identified based on the ratio of high and low frequency energy in their signal spectra 2 do spectral ratios separate mine blasts from earthquakes for all source areas 3 will spectral ratio discriminants be effective for identifying decoupled underground nuclear explosions we conclude that spectral ratios can sometimes separate events an example is separation of the titania mine blasts from the events at the nearby offshore locations although we cannot be sure how much this is due to path differences however in general spectral ratios vary as much within classes of events as they do among different classes the pne in our data set allows the simulation of spectra from a decoupled nuclear explosion by simply applying the frequency dependent decoupling factor to the observed pn spectrum for this event after applying a distance correction the spectrum for this simulated decoupled nuclear explosion is similar to those for the soviet union mine blasts in our data set

analysis of induced seismicity for stress field determination and pore pressure mapping the focal mechanisms of some one hundred microseismic events induced by various water injections have been determined within the same depth interval numerous stress measurements have been conducted with the htpf method when inverted simultaneously the htpf data and the focal plane solutions help determine the complete stress field in a fairly large volume of rock about 15 106 m3 these results demonstrate that hydraulically conductive fault zones are associated with local stress heterogeneities some of these stress heterogeneities correspond to local stress concentrations with principal stress magnitudes much larger than those of the regional stress field they preclude the determination of the regional stress field from the sole inversion of focal mechanisms in addition to determining the regional stress field the integrated inversion of focal mechanisms and htpf data help identify the fault plane for each for each of the focal mechanisms these slip motions have been demonstrated to be consistent with terzaghi s effective stress principle and a coulomb friction law with a friction coefficient ranging from 0 65 to 0 9 this has been used for mapping the pore pressure in the rock mass this mapping shows that induced seismicity does not outline zones of high flow rate but only zones of high pore pressure for one fault zone where no significant flow has been observed the local pore pressure has been found to be larger than the regional minimum principal stress but no hydraulic fracturing has been detected there

environmental control of carbon isotope variations in pennsylvania black shale sequences midcontinent u s a abstract a reversal of the conventional carbon isotope relationship terrestrial lighter than marine organic matter has been documented for two pennsylvanian desmoinesian cyclothemic sequence cores from the midcontinent craton of the central united states deep water organic rich phosphatic black shales contain a significant proportion of algal derived marine organic matter as indicated by organic petrography rock eval hydrogen index and c 27 c 29 sterane ratios and display the lightest 13c values max 27 80 for kerogen while shallower water more oxic facies e g fossiliferous shales and limestones contain dominantly terrestrial organic matter and have heavier 13ckerogen values to 22 87 for a stratigraphically adjacent coal 13c values for extract fractions were relatively homogeneous for the organic rich black shales with the lightest fraction often the aromatics being only 1 or less more negative than the kerogen differences between extract fractions and kerogens were much greater for oxic facies and coals e g saturates nearly 5 lighter than the kerogen a proposed depositional model for the black shales calls upon a large influx of nutrients and humic detritus to the marine environment from the laterally adjacent extremely widespread pennsylvanian peat swamps which were rapidly submerged by transgression of the epicontinental seas in this setting marine organisms drew upon a co2 reservoir which was in a state of disequilibrium with the atmosphere being affected by isotopically light recycled co2 derived from the decomposition of peaty material in the water column and possibly from the anoxic diagenesis of organic matter in the sediments

prediction of source rock characteristics based on terpane biomarkers in crude oils a multivariate statistical approach abstract the distributions of eight tricyclic and eight pentacyclic terpanes were determined for 216 crude oils located worldwide with subsequent simultaneous rq mode factor analysis and stepwise discriminate analysis for the purpose of predicting source rock features or depositional environments five categories of source rocks are evident nearshore marine i e paralic deltaic deeper water marine lacustrine phosphaticrich source beds and ordovician age source rocks the first two factors of the rq mode factor analysis describe 45 percent of the variation in the data set the tricyclic terpanes appear to be twice as significant as pentacyclic terpanes in determining the variation among samples lacustrine oils are characterized by greater relative abundances of c 21 diterpane and gammacerane nearshore marine sources by c 19 and c 20 diterpanes and oleanane deeper water marine facies by c 24 and c 25 tricyclic and c 31 plus c 32 extended hopanes and ordovician age oils by c 27 and c 29 pentacyclic terpanes although thermal maturity trends can be observed in factor space the trends do not necessarily obscure the source rock interpretations also since bacterial degradation of crude oils rarely affects tricyclic terpanes biodegraded oils can be used in predicting source rock features the precision to which source rock depositional environments are determined might be increased with the addition of other biomarker e g steranes and stable isotope data using multivariate statistical techniques

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

correlation of natural gas by use of carbon isotopic distribution between hydrocarbon components the natural distribution of carbon isotopes between hydrocarbon gas components is used for 1 determining a gas s maturity 2 correlating a reservoired gas to its source 3 correlating one reservoired gas with another and 4 recognizing gas mixtures calculated separations of carbon isotopes between the normal alkane components of a natural gas have been related to source rock maturity by use of a single continuous diagram independent of source type actual data from a wide variety of geologic settings and geologic ages confirm this relationship and demonstrate its applicability to the source rock levels of organic metamorphism ranging from 8 to 13 covering the entire range of oil and wet gas generation at greater maturities the wet gas components are found to undergo thermal degradation losing their usefulness for correlation three examples showing indigenous gas west texas non indigenous gas gippsland basin australia and gas mixtures from multiple sources southeastern alberta illustrate exploration applications

paleovegetation and climatic conditions in a refugium of temperate plants in central japan in the last glacial maximum abstract paleovegetation and climatic conditions in the last glacial maximum lgm ca 24 4 and 20 1 ka were reconstructed based on plant macrofossils and pollen assemblages deposited in a sandy channel outcropped in the hanamuro river ibaraki prefecture central japan the plant macrofossil assemblages were composed of 31 arboreal and 76 herbaceous taxa occurrence of plants with various habitat preferences exhibited distribution patterns of highly diverse vegetation types depending on geomorphology and humidity in and around the drainage of the hanamuro river rich aquatic and wetland flora indicates an expansion of backmarsh mosaic environments along the river channel in the bottom of the valley wetland forests composed of picea sect picea assignable to picea koyamae and riparian forests dominated by alnus inokumae are well represented in the macrofossil assemblages pinaceous conifers were dominant in mesic or dry places with betula and the other deciduous broadleaved trees macrofossils and pollen indicates that abies veitchii was distributed in mesic locations larix kaempferi and picea jezoensis var hondoensis were on the upper slopes and pinus koraiensis was dominant on the plateau dominant selaginella remotifolia and the other drought intolerant understory herbs indicate closed canopy of mesic coniferous forests while many kinds of meadow and or ruderal plants were indicative of open vegetation along the river and slopes annual mean temperature of the fossil site based on occurrence of selaginella remotifolia was 8 1 c which is observed in present cool temperate zones where deciduous broad leaved trees are dominant this indicates that the distribution limit of subarctic conifers shifted to warmer temperature conditions than at present the overlapping distribution of temperate and subarctic plants occurred widely in the lowlands in the distribution ranges of temperate trees south of around 38 n in japan in the lgm with lower precipitation dryness was an important environmental factor that controlled plant distribution along with temperature water stress confined temperate broad leaved trees to the humid valley bottoms and relieved conifers from competition against broad leaved trees to promote their expansion to warmer regions macrofossils indicate the persistence of temperate plants in humid inland and or northern refugia during the lgm locations conducive to paleolithic human occupation

quantification and characterization of regional seismic signals from cast blasting in mines a linear elastic model summary cast blasts in coal mines designed to move large volumes of overburden are a source of large 1 5 kt frequent explosions in parts of the world with near surface coal resources mining events of this source type are triggering the prototype international monitoring system for the comprehensive test ban treaty being tested under the group of scientific experts technical test 3 gsett 3 we wish to develop techniques to distinguish between the seismic signals produced by these explosions and equivalent size single or point sources to that end we have developed a linear elastic model to simulate regional distance seismograms from mining cast blasts cast blasting involves a shot array with delayed detonations casting rock horizontally into a pit we model the effects of the millisecond delay firing pattern the depth of the pit and the cast of material into the pit we attempt to separate the effects due to the explosion the vertical movement of mass and the horizontal movement of mass in order to produce a physical understanding of the resulting waveforms which can be used to assess potential discriminants for these types of explosions these physical models of source processes are constrained by near surface measurements of cast blasts in ne wyoming that are triggering gsett 3 two observational results at regional distances that are replicated by these models are the excitation of 8 12s surface waves by the cast blasts and the insensitivity of peak amplitude to total explosive size for normal blasting practices the insensitivity of peak amplitudes from the cast blast to total source size is a consequence of the delay firing practice under normal procedures this practice was initiated to reduce ground motions in the near source region around the mine and it appears that it is also successful in controlling peak amplitudes at regional distances the mass transfer into the pit has both a vertical and a horizontal force component each of which contribute to the final seismogram the latter being azimuthally dependent assuming maximum coupling the contribution to the seismogram due to the vertical force component is approximately equal to the explosion contribution for pit depths of about 10 m but dominates for pit depths of 20 m or greater the contribution due to the horizontal force component is mainly in the enhanced rayleigh waves comparison of high frequency seismic radiation from the single shot and cast blast shows little qualitative difference in the regional waveforms

characterising the nickel isotopic composition of organic rich marine sediments new ni stable isotope data 60ni determined by double spike mc icp ms for two geologically distinct suites of organic rich marine sediments from the sinemurian pliensbachian s p global stratotype section and point gssp robin hood s bay uk and the devonian mississippian exshaw formation west canada sedimentary basin is presented herein these sediments yield 60ni values of between 0 2 and 2 5 and predominantly have ni isotopic compositions that are heavier than those of abiotic terrestrial and extraterrestrial samples 0 15 and 0 27 and in some cases present day seawater 1 44 and dissolved ni from riverine input 0 80 in addition the observed degree of isotopic fractionation in the marine sediments is far greater than that of these other sample matrices however a strong similarity is exhibited between the 60ni values of the organic rich sediments studied here and those of ferromanganese crusts 0 9 2 5 suggesting that factors ubiquitous to the marine environment are likely to play a key role in the heightened level of isotopic fractionation in these sample matrices a lack of correlation between the ni stable isotope compositions of the organic rich sediments and ni abundance suggests that isotopic fractionation in these sediments is not controlled by incorporation or enrichment of ni during sediment accumulation further no relationship is observed between 60ni and toc concentrations or bottom water redox conditions indicating that the organic carbon reservoir and levels of oxygenation at the sediment water interface do not exert a primary control on ni isotope fractionation in marine sediments following examination of these relationships it is therefore more likely that the heavy ni isotope compositions of marine sediments are controlled by the weathering environment and the dominant sources of dissolved ni into the global ocean reservoir

origin of nitrogen rich natural gases in the california great valley evidence from helium carbon and nitrogen isotope ratios abstract dry natural gases produced from the sacramento and northern san joaquin basins contain up to 87 nitrogen 15n measurements for gases with n2 8 vary from 0 9 to 3 5 methane 13c values vary from 61 to 15 3 he 4 he ratios indicate the presence of mantle derived helium in addition to radiogenic crustal helium and suggest that the gases may originate from mixing between three principal components a hydrocarbon rich gas with 3 he 4 he 0 1r a derived from the microbial and thermogenic alteration of sedimentary organic matter a hydrocarbonrich gas with 3 he 4 he 2 75r a derived from the localized pyrolysis of sediments by magmatic volatiles and a nitrogenrich gas with 3 he 4 he 1r a the nitrogen rich component is characterized by methane 13c less negative than 25 and n 2 ar ratios as high as 22 000 nitrogen concentrations tend to increase towards the basement along the shallow eastern margin of the valley suggesting that the nitrogen rich component is derived from metasedimentary rocks deep within the crust the coast ranges fraciscan complex which was thrust well beneath the great valley during late mesozoic and early cenozoic subduction appears to be the most likely source

palaeogene evolution of deformation in the northeastern iberian peninsula during the palaeogene alpine compression three units were differentiated in the studied area south of the ebro basin the catalan coastal range dominated by ne sw major basement faults with a sinistral movement the iberian range where the important basement faults have a nw se direction and a reverse movement often with a dextral component the linking zone between these two ranges where an e w dominant structural direction is marked by an array of folds and thrusts with a northward vergence in the mesozoic cover from the analysis of both these major structures and the small scale structures it can be deduced that the compression in the studied area has evolved from a nw se direction lower middle eocene to a n s direction and to a ne sw one uppermost oligocene the major structures are due to the n s compression later the stress field progressively changed to a distensive regime we suggest a relation between the compressive phases and the displacement direction of the iberian plate with reference to the european plate

stable carbon isotope compositions of crude oils application to source depositional environments and petroleum alteration the carbon isotopic composition of the c15 saturate and aromatic hydrocarbon fractions and the gas chromatographs of the c15 saturate fraction of 339 oils were geochemically and statistically evaluated results of this study show that the average isotopic compositions of the c15 aromatic hydrocarbon fractions of oils sourced from terrigenous or marine organic matter are identical the average isotopic composition of the c15 saturate fraction of oils derived from terrigenous organic sources is slightly more negative 0 9 pmil than the average for marine oils but this difference is insufficient to be used as a reliable source indicator reports in the literature stating that marine oils are isotopically more positive than te rigenous oils and that the difference can be utilized to distinguish between the two are therefore not supported by this study the isotopic differences between oils sourced from terrigenous and marine organic matter do not manifest themselves in the range of absolute values of one oil fraction but rather in the isotopic relationship between the saturate and aromatic hydrocarbon fractions the isotopic relationship is the following oils of terrigenous organic source dgr13caro 1 12 dgr13csat 5 45 oils of marine organic source dgr13caro 1 10 dgr13csat 3 75 the difference between the two equations was evaluated statistically and a statistical parameter cv the canonical variable cv 2 53 dgr13csat 2 22 dgr13caro 11 65 was used to distinguish between marine and terrigenous oils cv values larger than 0 47 indicate predominantly a terrigenous organic source for the oil whereas cv values smaller than 0 47 indicate mostly a marine organic source thermal maturity differences in oils and isotopic variations in the source beds can cause as much as 2 pmil variations in the isotopic composition of one family of oils finally stable carbon isotopes can in some situations help correlate biodegraded oils to their nondegraded counterparts

late quaternary vegetation and climate changes inferred from a pollen record of dongyuan lake in southern taiwan abstract a pollen record sampled from a valley basin in southern taiwan shows the environmental change specifically vegetation and climate that has occurred there since 22 000 cal yr bp in contrast to the subtropical evergreen forest found there today temperate broadleaved and conifer mixed forest occupied the basin between 22 000 and 16 000 cal yr bp which suggests that climate conditions were considerably cold during the last glacial maximum lgm and early deglacial period during the interval from 16 000 to 11 400 cal yr bp this basin was situated near an ecotone of two altitudinal vegetation zones i e a temperate conifer broadleaved mixed forest and a warm temperate evergreen forest which suggests the gradually warming climate conditions of the late glacial period the climate experienced further warming between 11 400 and 8200 cal yr bp as evidenced by the dominance of warm temperate evergreen forest elements subsequently the subtropical evergreen forest prevailed in the basin between 8200 and 4100 cal yr bp which reflects a considerably warmer mid holocene in addition tropical evergreen forest appeared in the area circa 6100 cal yr bp marking the holocene thermal optimum hto following that a warm temperate evergreen forest thrived between 4100 and 2100 cal yr bp finally a subtropical evergreen forest began its reemergence in the basin from 2100 cal yr bp and continues to grow there today from a comparison of these changes in vegetation we propose that 1 the annual mean temperature of the lgm was at least 7 c lower than today and 2 the hto was at least 2 c higher than present

organic geochemistry depositional history and hydrocarbon generation modelling of the upper permian kupferschiefer and zechstein limestone strata in south west poland abstract the upper permian zechstein limestone carbonates in the south western part of the polish zechstein basin contain small quantities of organic matter usually less than 0 1 wt toc and have poor hydrocarbon potential in contrast the kupferschiefer shales have excellent hydrocarbon potential with toc as high as 10 8 wt predominantly algal type ii kerogen generally thermal maturity of the organic matter is 0 6 0 9 vitrinite reflectance while locally is as high as 1 45 the kimmerian and laramian tectonic events significantly influenced the regional burial and thermal history the main subsidence of the kupferschiefer zechstein limestone complex took place during the late permian late triassic period with additional burial during the jurassic and late cretaceous hydrocarbon generation from the kupferschiefer source rocks occurred from middle triassic to late jurassic times reaching maximum rates during the jurassic the cretaceous subsidence had only a minor influence on the maturity and transformation of organic matter expulsion started between late triassic in the western part of the study area and early jurassic in the eastern part then ceased by the late jurassic early cretaceous erosion the total amount of generated and expelled hydrocarbons from source rocks was small because their thickness was limited therefore kupferschiefer shales cannot be considered as source rocks for liquid hydrocarbons but may be a potential source for gas accumulated in the zechstein limestone and rotliegend reservoirs

the time frequency characteristics of quarry blasts and calibration explosions recorded in kazakhstan ussr summary in this paper we consider two fundamentally different processes that can be responsible for the organization of energy in seismic coda into discrete time independent frequency bands one process involves the resonance of energy in low velocity horizons and the other requires the interaction of time offset wavefields produced by subevents within multiple event mine explosions ripple fired quarry blasts we examined data collected by high frequency seismometers in kazakhstan ussr and observed regular time independent spectral modulations in coda resulting from events strongly suspected to be soviet quarry blasts but not in the coda from single event calibration explosions detonated at similar ranges we conclude these modulations are a source effect and due to ripple firing this modulation is independent of the source receiver azimuth and we infer that the spatial array of subshots in each event must be small we demonstrate that simple linear superposition theory can be used to reproduce effectively the spectral modulation observed in real quarry blasts on the basis of these observations we attempt to discriminate between the two types of events using a spectral pattern based algorithm that seeks time independent features we consider the detrimental effect that resonant energy in low velocity horizons can have on the successful application of our algorithm

quantitative pollen based climate reconstruction in central japan application to surface and late quaternary spectra abstract climate reconstruction in japan by the best modern analogues method was tested with 285 surface pollen spectra and then applied to the 47 000 years pollen profile from lake mikata central japan both pollen taxa percentages and plant functional type affinity scores were used in the reconstruction of six climate variables the reconstructed values were compared with the estimated modern climate at each surface pollen site in order to evaluate the accuracy of the pollen based reconstruction the reconstruction of thermal parameters is very reliable correlation coefficient r between 0 86 and 0 89 the reconstruction of annual precipitation is less accurate r 0 7 we also proposed a new technique to calibrate reconstructed values into both probability distribution and or confidence regions of observed values the specialized programs for this calibration polcalib and polhist are available at qsr website http www elsevier nl locate quascirev the reconstruction of the late quaternary climate changes around lake mikata shows that the summer and winter temperatures were 5 c lower than present around 40 uncal kyr bp reached a minimum around 20 uncal kyr bp 10 c lower than present and became similar to present day at 8 uncal kyr bp the estimates for annual precipitation show that it was driest around 20 uncal kyr bp

sulfur isotope ratios in petroleum research and exploration williston basin the three major types of crude oil in the williston basin the type i oils of the winnipeg red river system the type ii oils of the bakken madison system and the type iii oils of the tyler pennsylvanian system can be distinguished by their sulfur isotope compositions they have characteristic dgr34s values of 5 8 1 2 parts per thousand ppt 2 8 0 8 ppt and 4 0 0 7 ppt respectively highly mature oils have less typical values type ii oils which have migrated over a distance of some 150 km beyond the region of generation have maintained their characteristic dgr34s values even though sulfur may have been lost this indicates little or no interaction with reservoir sulfates under normal circumstances on the periphery of the basin type ii oils altered by water washing and biodegradation have altered dgr34s values which increase from 2 9 to 9 4 ppt with the increasing degree of crude oil degradation the bakken shales source of the type ii oils have dgr34s distribution patterns in the reduced sulfur typical of marine sediments the dgr34s values for the type ii oils match most closely the dgr34s value of organic sulfur in the black bituminous shales of the lower bakken

effects of thermal maturation on stable organic carbon isotopes as determined by hydrous pyrolysis of woodford shale acquiring crude oils that have been expelled from the same rock unit at different levels of thermal maturation is currently not feasible in the natural system this prevents direct correlation of compositional changes between the organic matter retained in a source rock and its expelled crude oil at different levels of thermal maturation alleviation of this deficiency in studying the natural system requires the use of laboratory experiments natural generation of petroleum from amorphous type ii kerogen in the woodford shale may be simulated by hydrous pyrolysis which involves heating crushed rock in contact with water at subcritical temperatures 374 c four distinct stages of petroleum generation are observed from this type of pyrolysis 1 pre oil generation 2 incipient oil generation 3 primary oil generation and 4 post oil generation the effects of thermal maturation on the 13c values of kerogen bitumen and expelled oil like pyrolysate from the woodford shale have been studied through these four stages of petroleum generation similar to the natural system the kerogens isolated from the pyrolyzed rock showed no significant change in 13c this suggests that the 13c value of kerogens may be useful in kerogen typing and oil to source rock correlations 13c values of bitumens extracted from the pyrolyzed rock showed an initial decrease during the incipient oil generation stage followed by depletion during the primary and post oil generation stages this reversal is not favorable for geochemical correlation or maturity evaluation saturated and polar components of the bitumen show the greatest 13c variations with increasing thermal maturation the difference between the 13c of these two components gives a unidirectional trend that serves as a general indicator of thermal maturation and is referred to as the bitumen isotope index bii 13c values of the expelled pyrolysates show a unidirectional increase with increasing thermal maturation the constancy and similarity of 13c values of the aromatic components in the expelled pyrolysates and bitumens with increasing thermal maturation encourages their use in oil to oil and oil to source rock correlations isotopic type curves for expelled pyrolysates indicate that they may be useful in oil to oil correlations but have a limited use in oil to source rock correlations

determination of kerogen maturity by the pyrolysis carbon isotope method abstract the premise of the proposed maturation procedure is that immediately after post depositional microbial alteration of organic matter there is a degradable but not renewable pool of non extractable methane precursor carbon that becomes smaller as methane is produced with increasing time and temperature in addition the methane progressively becomes isotopically heavier because of mass balance and bonding considerations a maturity index based on the isotopic difference between the total accumulated methane produced by pyrolysis and the kerogen carbon and or the mole ratio of methane to kerogen carbon is presented published data by chung and sackett geochim cosmochim acta43 1979 1988 1979 for a suite of 19 coals and 12 shales of various ranks and maturities support this procedure

source rock contributions to the lower cretaceous heavy oil accumulations in alberta a basin modeling study the origin of the immense oil sand deposits in lower cretaceous reservoirs of the western canada sedimentary basin is still a matter of debate specifically with respect to the original in place volumes and contributing source rocks in this study the contributions from the main source rocks were addressed using a three dimensional petroleum system model calibrated to well data a sensitivity analysis of source rock definition was performed in the case of the two main contributors which are the lower jurassic gordondale member of the fernie group and the upper devonian lower mississippian exshaw formation this sensitivity analysis included variations of assigned total organic carbon and hydrogen index for both source intervals and in the case of the exshaw formation variations of thickness in areas beneath the rocky mountains were also considered all of the modeled source rocks reached the early or main oil generation stages by 60 ma before the onset of the laramide orogeny reconstructed oil accumulations were initially modest because of limited trapping efficiency this was improved by defining lateral stratigraphic seals within the carrier system an additional sealing effect by biodegraded oil may have hindered the migration of petroleum in the northern areas but not to the east of athabasca in the latter case the main trapping controls are dominantly stratigraphic and structural our model based on available data identifies the gordondale source rock as the contributor of more than 54 of the oil in the athabasca and peace river accumulations followed by minor amounts from exshaw 15 and other devonian to lower jurassic source rocks the proposed strong contribution of petroleum from the exshaw formation source rock to the athabasca oil sands is only reproduced by assuming 25 m 82 ft of mature exshaw in the kitchen areas with original total organic carbon of 9 or more

bakken madison petroleum systems in the canadian williston basin part 3 geochemical evidence for significant bakken derived oils in madison group reservoirs there have been two different definitions of the upper devonian mississippian bakken madison petroleum systems in the canadian williston basin early studies proposed the bakken shales as the source for oils in both the bakken formation and madison group reservoirs more recent studies suggested two separate sources for these oils thus the bakken oils were interpreted to be derived from the bakken formation shales and the madison group oils from a carbonate source within the madison group the present study utilized quantitative results of molecular markers across gasoline range light hydrocarbons saturated and aromatic hydrocarbon fractions in 122 oil samples to re evaluate the oil oil and oil source relationships the steroid and hopanoid parameters collected in this study have confirmed the diagnostic features for end member bakken and lodgepole sources whereas a range of other molecular markers revealed compositional continuums occurring between the two oil families the recognition of more extensive mixing of bakken derived oils in madison group reservoirs along a sw ne trending fault fracture zone in southeastern saskatchewan indicates focused migration pathways for bakken oils and thus upward resource potentials the results also suggest caution with the use of conventional biomarker data in oil oil and oil source correlation when the different sources concerned contain biomarkers in drastically different concentrations

origins of methane discharging from volcanic hydrothermal geothermal and cold emissions in italy abstract we have addressed the origins of methane in fumarolic thermal and cold emissions discharging from a diversity of geological settings spread all over the italian peninsula and at panarea and pantelleria islands fluid discharges from the main geothermal systems of the peri tyrrhenian area including mt amiata larderello latera and manziana show 13c ch4 and d ch4 values 28 v pdb and 160 v smow respectively and c1 c2 concentration ratios 1000 these patterns suggest that ch4 discharged from these systems is primarily generated by abiogenic reduction of co2 and or co methane seems to have at least partially a different origin than the higher hydrocarbons that might be entirely related to the thermal decomposition of organic matter or alternatively to methane polymerization fumaroles from the volcanic systems of solfatara vesuvio panarea and pantelleria have c1 c2 concentration ratios in a wide range from 17 to 4300 but 13c ch4 and d ch4 values 21 v pdb and 120 v smow respectively such isotopic values are very similar to those reported for ch4 discharging from ultramafic hydrothermal systems in agreement with recent evidence provided for solfatara and pantelleria we therefore infer that the ch4 in the volcanic fumaroles is mainly abiogenic too the 13c ch4 from 21 6 to 36 9 v pdb and d ch4 from 113 to 164 v smow values as well as the c1 c2 concentration ratios from 19 to 2240 in the co2 rich fluid discharges located between the geothermal volcanic systems and the apennine sedimentary chain tend to decrease eastwards as the temperatures of the fluid reservoirs progressively diminish suggesting that the ch4 production is mainly related to thermogenic processes according to this general trend the ch4 dominated fluids from mud volcanoes located eastwards of the co2 rich emissions are fed by an almost pure thermogenic source the easternmost fluid discharges from the po valley and the adriatic coast where organic matter evolves at relatively shallow depths in the presence of a low geothermal gradient record the lowest 13c ch4 and d ch4 values i e as low as 69 v pdb and

sg06 a fully continuous and varved sediment core from lake suigetsu japan stratigraphy and potential for improving the radiocarbon calibration model and understanding of late quaternary climate changes abstract the high potential of the varved sediments of lake suigetsu central japan to provide a purely terrestrial radiocarbon calibration model and a chronology of palaeoclimatic changes has been widely recognised for the last two decades however this potential has not been fully realised since the only available long sediment core from the lake sg93 was extracted from a single bore hole and was therefore interrupted by gaps of unknown duration between successive core sections in the summer of 2006 a new sediment core sg06 was recovered from the lake four separate boreholes were drilled and the parallel sets of cores recovered were found to overlap completely without gaps between segments this new record provides the ability to test existing atmospheric radiocarbon calibration models as well as to assess the scale of inter regional leads and lags in palaeoclimatic changes over the last glacial interglacial cycle multi disciplinary analyses from sg06 are still ongoing but a reliable description of the sedimentary sequence needs to be provided to the wider science community before major outputs from the project are released thereby allowing fully informed critical evaluation of all subsequent releases of data based on the sg06 record in this paper we report key litho stratigraphic information concerning the sg06 sediment core highlighting changes in the clarity of annual laminations varves with depth and possible implications for the mechanism of the climate change we also discuss the potential of the sg06 record to meet the fundamental goals of the inqua intimate project