depositional environment and oil generation in ordovician source rocks from southwestern ontario canada organic geochemical and petrological approach the ordovician trenton group sherman fall and cobourg formations and the lindsay collingwood member and blue mountain formations of southwestern ontario were examined using rock eval pyrolysis gas chromatography gas chromatography mass spectrometry and incident light microscopy to evaluate their paleodepositional environments thermal maturities and source rock potential all units contain sufficient amount of oil prone type ii predominantly marine organic matter to be considered as petroleum source rocks unstructured bituminite with varying proportions of unicellular alginite are the dominant dispersed organic matter macerals the bituminite typically occurs in massive to laminated granular or patchy populations that commonly show microtextural relationships persistent inclusions of leiosphaeridia telalganite demonstrate that planktonic algal debris was a primary organic substrate for blooming microbes disseminated coccoidal gloeocapsomorpha prisca is found in minor amounts usually in association with common to abundant acritarchs zooclasts chitinozoa graptolites scolecodonts and solid bitumen also are present as maceral inclusions within the bituminite network the biomarker distributions for all of the studied units are those expected for marine organic matter deposited in a clastic dominated environment the extracts are characterized by a smooth n alkane profile with low abundance of c20 members typical for marine derived organic matter pristane phytane ratios range from 0 97 to 1 72 indicating dysoxic conditions during deposition smooth c31 c35 homohopane profiles ts tm ratios typically above 1 0 and a higher concentration of diasteranes relative to regular steranes all appear to indicate the clay bearing character of these rocks the predominance of c30 hopane over c29 regular sterane is interpreted to reflect a primary microbial input and extensive reworking of the organic matter optical reflectance fluorescence and geochemical tmax biomarker data thermal maturity parameters indicate that the trenton and blue mountain strata are within the zone of prolific oil generation throughout the whole area of study the collingwood shales are mature with respect to petroleum generation in the eastern part toronto area and only marginally mature in the northern part georgian bay area of the study area in general the biomarker composition of the extracts from all examined units is compatible with that of the oils found in the trenton reservoirs of southwestern ontario however geochemical and geological evidence suggests that the organic rich shaly laminae within the trenton group are the principal source of these oils accumulation of organic carbon in the ordovician sediments of southern ontario is suggested to derive from low energy normal marine environments grading from shallow shelf into deep shelf and open basinal settings the nutrient availability and consequently higher bioproductivity more intense consumption of oxygen and progressing anoxia controlled by a low latitude location diminished water circulation stratification of the water column and a depressed pycnocline resulted in high preservation rates the amorphous nature of kerogen reflects significant microbial interaction at the water sediment interface and within the sediments where reducing conditions must have periodically predominated

stratigraphy correlation and sedimentary history of adelaidean late proterozoic basins in australia abstract adelaidean late proterozoic time is represented by the precambrian portion of the thick sequence in the adelaide geosyncline its stratotype basin in south australia comparable adelaidean sedimentation including the deposition of glaciogenic sediments is recorded in other intracratonic and epicratonic basins extending northwards across australia in the adelaide geosyncline which lies to the east of the gawler craton and its cratonic platform cover the stuart shelf up to 15 km of mainly shallow water sediments accumulated partly in intracratonic troughs and perhaps partly on a miogeoclinal continental shelf the earliest sedimentation is associated with rifting and basic volcanism with an estimated age of ca 1100 ma it commenced with basal blanket sands shelf carbonates and basaltic volcanics followed by mixed carbonate clastic and evaporitic beds callanna beds the overlying burra group consists of a number of west derived possibly deltaic cycles and magnesite bearing platform carbonates the unconformably overlying late adelaidean umberatana group contains the lower glacial beds including the sturt tillite interglacial siltstone dated at about 750 ma and carbonate and the upper glacial beds the post glacial wilpena group commences with a distinctive cap dolomite above the upper glacials and contains mainly fine to medium clastics and the ediacara metazoan assemblage late adelaidean sedimentation patterns are sufficiently similar in the officer amadeus ngalia and georgina basins of central australia and in the kimberley region western australia to suggest interconnection with the adelaide geosyncline to the south in the amadeus basin the early adelaidean sequence is younger than about 1050 ma but cannot be directly correlated with the early adelaidean formations of the adelaide geosyncline however the late adelaidean glacial and younger sequences are readily correlated they include the lower glacial areyonga formation and the arumbera sandstone i containing elements of the ediacara assemblage in the georgina and ngalia basins mainly late adelaidean sequences including thick glacials can mostly be correlated with the amadeus basin in the kimberley region earliest adelaidean clastics may be represented but only the late adelaidean glaciogenic and associated sediments can be correlated with confidence the tillites commonly overlie glaciated pavements the lower glacials are represented only in a graben while the upper glacials and succeeding sequence are more widespread post glacial shales have been dated at ca 670 640 ma the dominantly carbonate and clastic sequences of the bangemall basin western australia cannot be directly correlated with any type adelaidean but geochronology suggests an earliest adelaidean age ca 1050 ma

contributions of wind forcing waves and surface heating to sea surface height observations in the pacific ocean the dominant processes affecting sea surface height ssh variability observed by the topex poseidon altimeter vary regionally in the pacific baroclinic rossby waves equatorially trapped kelvin waves steric response to seasonal heating and the response to wind stress curl forcing are all important the steric response to surface heating dominates seasonal ssh variability in the subpolar gyre and the eastern subtropical gyre south of the kuroshio extension and south of 20 n in the eastern pacific the dominant contribution to ssh is from near annual period rossby waves to quantify the wave energy observed ssh was assimilated into a kinematic model of westward propagating waves these waves account for 70 of ssh variance between 10 s and 10 n but only 30 between 10 n and 30 n although wave energy in the eastern pacific is correlated with ssh anomalies at the equator the much larger wave energy in the western pacific is correlated with wind stress curl suggesting that the rossby waves there are locally forced in addition to these planetary waves the ocean response to wind forcing via ekman pumping is observed in several places specifically in the north equatorial current a quasi steady topographic sverdrup balance is detectable over most of the north pacific at latitudes as low as 10 15 n as well as in the south pacific where it is seen north of 50 s the decomposition of the ssh signal into propagating waves an ekman pumping response and sverdrup transport is consistent with the results from an isopycnal numerical model

subtidal bottom pressure observed at axial seamount in the northeastern continental margin of the pacific ocean since september 1987 bottom pressure bp has been observed at axial seamount 45 57 5 n 130 00 3 w 1540 m depth located 450 km off the oregon coast on the juan de fuca ridge observations from 1987 to 1992 show that subtidal axial bp is dominated by barotropic 2 to 5 mbar fluctuations with frequencies 1 9 cycles per day cpd they are slightly smaller than subtidal bp observed 720 km to the west during the ocean storms experiment and a factor of 2 4 smaller than the subtidal fluctuations of adjusted sea level asl at the coast for the period september 1987 to july 1988 axial bp and ocean storms bp are significantly coherent coh2 0 5 except at intraseasonal frequencies 1 100 1 20 cpd and in a band 1 8 1 6 cpd of low axial bp variance in the coherent frequency bands the phase relationships between the two bp series suggest independent atmospheric forcing on the other hand axial bp and coastal asl are not coherent except at the fortnightly tidal frequency looking for possible forcing of axial bp by the curl of the wind stress curl over the ne pacific data analyses show that axial bp and curl derived from european centre for medium range weather forecasts winds are significantly coherent in only two frequency bands one band narrowly peaked near 1 9 1 cpd for curl in regions south of axial seamount and a 1 5 1 3 5 cpd band for curl in a large region nw of the seamount in the 1 5 1 3 5 band axial bp also has a small amplitude spectral peak associated with bottom trapped baroclinic currents near axial seamount remote axial bp curl coherence at some frequencies is qualitatively consistent with the local forcing theory of lippert and muller 1995 that attributes the coherence to stable phase relationships and the spatial characteristics of the bp curl transfer function however the axial bp curl comparison is inhibited by the lack of accurate estimates of curl within 400 km of the coast fully understanding the origins and dynamics of subtidal bp at axial seamount will require a knowledge of how the complex topography in the region affects the barotropic and baroclinic responses to atmospheric forcing as well as the propagation of rossby and other waves

evidence for gloeocapsomorpha prisca in late devonian source rocks from southern alberta canada abstract organic rich intervals within the late devonian camrose member of southern alberta canada show optical and chemical characteristics very similar to those of ordovician samples whose organic matter is dominated by gloeocapsomorpha prisca derived alginite this includes saturate fraction gas chromatograms dominated by n alkanes with a pronounced odd carbon number up to c19 and much lower abundances of c19 n alkanes acyclic isoprenoids and biomarkers microscopy reveals these samples contain g prisca like alginite with a morphology that previously has been suggested for the growth of this organism under higher salinity conditions which is in agreement with the depositional environment of the camrose member one unusual feature of the g prisca rich samples is the very high concentration of c21 and c23n alkylnaphthalenes and n alkylbenzenes in the aromatic fractions of their extracts the origin of these compounds is not known but their occurrence could be related to the high concentrations of c21 and c23n alkyl phenols that have been noted in pyrolysates of estonian kukersites by previous workers other camrose member extracts show very different distributions that are more typical for carbonates deposited under anoxic higher salinity conditions many oils that occur in nisku formation reservoirs in the enchant hays field in southern alberta show saturate fraction gas chromatograms and other evidence that indicate an important contribution to these oils from the g prisca rich intervals these are thought to have a contribution from camrose member source rocks hence caution should be used in only attributing g prisca geochemical characteristics to cambro ordovician oils as on rare occasions they can also occur in younger source rocks and their derived oils

inferences for sources of oils from the norwegian barents sea using statistical analysis of biomarkers abstract conventional biomarker age indicators may not always give conclusive inferences for the age of an oil s source rock particularly with regard to condensates in which most of the key biomarkers are often too sparse to determine it is possible that other compounds reflecting changes in primary producer assemblages or depositional environment can provide age indications in basins that have experienced a progressive change in conditions the norwegian barents sea provides an opportunity to evaluate this approach although the gradual changes are punctuated by intervals of stratification oaes and extinctions partial least squares analysis was used to identify a number of apparently suitable parameters to establish an age calibration from source rock extracts and then to apply it to a variety of oils and condensates from the barents sea the resulting source age inferences are consistent with conventional age parameters for the normal oils providing a degree of confidence in their applicability to the problematic condensates in the main part of the hammerfest basin oils of jurassic origin dominate whereas contributions from triassic sources are suggested towards the margins particularly in pre jurassic reservoirs to the east on the norsel high and in the nordkapp basin the main oil sources are suggested to be early triassic although a palaeozoic possibly permian source is likely on the margin of the finnmark platform in well 7128 4 1 among the novel parameters the relative abundances of phytanyl arenes and diadrimanes appear to be controlled by diagenetic conditions

the global distribution of f h and the barotropic response of the ocean the barotropic response of the ocean over smoothly varying topography is directly related to the potential vorticity gradient f h a global estimate of f h and f h have been constructed from a high resolution digital topographic data base four different regimes of the barotropic response of the ocean are suggested by these maps 1 in the tropical latitudes from 20 s to 20 n f h h the response will be similar to a flat bottom sverdrup regime 2 in mid latitudes 20 to 70 north of 30 s f h h the response will be quasi stationary weak and dominated by nonlocal forcing flow along isolines of f h 3 in a number of small regions throughout the mid latitudes in both hemispheres f h h in these regions the local response flow across isolines of f h should be amplified and wavelike motions may occur over a broader bandwidth of frequencies 4 south of 30 s the mid ocean ridge system becomes zonal and isolates several large regions within closed lines of f h in these regions principally the abyssal plains of the southern ocean the low frequency barotropic response of the ocean may be wavelike in character and much stronger than the sverdrup response consequently this analysis suggests that the southern ocean may have a stronger barotropic response to wind forcing than the other five major ocean basins

distribution and structure of hydrocarbons in four organic rich ordovician rocks abstract organic matter in four north american rocks of ordovician age has been analysed using geochemical and optical techniques including reflected light and fluorescence microscopy rock eval pyrolysis elemental analysis of isolated kerogens gas chromatography gc and gas chromatography mass spectrometry gc ms of hydrocarbons in the solvent extracted bitumens the samples analysed were guttenberg oil rock and black shales from the vinini womble and big fork formations in the united states the origin of some of the biomarkers found in the bitumen and the vitrinite particles observed in reflected light are discussed briefly with reference to possible algal and bacterial precursors the results indicate that the four samples are potentially excellent oil source rocks although the guttenberg oil rock is too immature to have generated a substantial quantity of hydrocarbons

discrimination of bitumen sources in precambrian and lower palaeozoic rocks southern u k by gas chromatography mass spectrometry abstract two distinct sources for bitumen shows in lower palaeozoic and precambrian rocks in the welsh borderland can be successfully discriminated using gas chromatography mass spectrometry bitumens are widespread in the region in rocks from late precambrian longmyndian to silurian age previous geological studies have suggested that some bitumens originated from pre devonian source rocks while others migrated downwards laterally from carboniferous rocks this possibility has now been confirmed by organic geochemical studies which have also clarified the origin of some bitumens whose affinities had not been clear those bitumens concluded to have migrated from the carboniferous have also been correlated with bitumens within carboniferous rocks further east they are characterized by relatively high levels of hopanes c 27 c 29 to c 35 max c 29 or c 30 the bitumens with an assumed pre devonian source contain n alkylcyclohexanes range c 15 to c 32 max c 18 or c 19 which are absent in the other bitumens and they can be matched with a longmyndian black shale although detailed correlations are limited by the very high maturity of the samples the pre devonian bitumens also show several affinities with the distinctive ordovician oils

biochemical evolutionary significance of ordovician oils and their sources abstract geochemical data from several ordovician oils and kerogens from distinct basins in canada united states estonia and australia show some unique compositional characteristics the oils analyzed by gas chromatography and gas chromatography mass spectrometry are characterized by an odd dominance in the c9 c19 molecular weight range of normal paraffins and an odd dominated homologous series of cyclohexyl substituted normal paraffins the oils contain an unusually small amount of c20 components and pristane and phytane are conspicuous by their virtual absence the compositions of the oils and kerogens correlate closely and display characteristics that have not been observed in younger sediments the predominant organism found in the source kerogens for these unique oils is gloeocapsamorpha prisca a primitive prokaryotic organism data from the analysis of gloeocapsamorpha rich kerogens and the association of this organism with ordovician source rocks indicate a genetic relationship exists between the organism and the unusual oil chemistry the chemistry of the oils and kerogens suggests that gloeocapsamorpha was either non photosynthetic or that it fixed light using a chlorophyll that did not contain a phytyl side chain e g a bacteriochlorophyll the widespread occurrence of oils and kerogens possessing such a uniform composition appears unique to the ordovician certainly to the early paleozoic this suggests that paleocological conditions of ordovician anoxic environments were very similar and g prisca was particularly well adapted to these conditions

a quasi geostrophic circulation model of the northeast pacific part i a preliminary numerical experiment abstract a limited area quasi geostrophic numerical model with mesoscale resolution is developed to study the circulation in the northeast ne pacific ocean the model domain extends from the british columbia alaska coast out to 170 w and down to 45 n and incorporates the coastline geometry and bottom topography of the region a long term integration was conducted using a steady climatological wind stress curl field to drive the circulation several statistical properties of the solution are determined and compared with observations a cyclonic circulation develops in the model basin with a meandering alaska current feeding at the head of the gulf of alaska into an intense boundary current corresponding to the alaskan stream the head of the gulf is a region where anticyclonic closed streamline features are occasionally generated with characteristics resembling those of the sitka eddy in the downstream region the boundary current separates and is subject to lateral meandering due to topographic wave

comparison of michigan basin crude oils abstract michigan basin oils from the ordovician trenton silurian niagaran and devonian dundee formations have been geochemically compared by gc gc ms and carbon isotope mass spectrometry one oil from each formation was selected for detailed analysis which included measurement of individual n alkane 13 c values the ordovician and devonian oils are strikingly similar to one another yet clearly different from the silurian oil this pattern is unexpected because ordovician and devonian reservoirs are physically separated by the silurian strata from time temperature considerations the devonian oil probably was formed in older strata and has migrated to its present location our analyses suggest a common source for the devonian and ordovician oils

middle ordovician organic matter assemblages and their effect on ordovician derived oils two distinct middle ordovician oil prone organic matter assemblages occur in thermally immature to marginally mature petroleum source rocks from iowa the substantially more oil prone assemblage a generates the unique ordovician oil fingerprint which has been associated with the organic walled microfossil gloeocapsamorpha prisca the second assemblage b generates a more ordinary signature the two assemblages which are mixed or interbedded in many ordovician sediments of north america explain the variations in oils derived from ordovician source rocks these mixtures also aid in interpretation of the chemistry of g prisca core samples examined are from three wells in iowa penetrating the primarily carbonate sequence from the guttenberg member of the decorah formation down to the st peter sandstone microscopy rock eval pyrolysis and capillary gas chromatography on source rock bitumen extracts and nearby oils were used to evaluate the two assemblages solvent extracts from rocks containing predominantly assemblage a have the diagnostic ordovician gas chromatographic signatures with an odd preference in c11 c19 normal alkanes low amounts of heavier normal alkanes and virtual absence of isoprenoids including pristane and phytane although assemblage a occurs only in very thin beds it is potentially so oil generative that thicknesses in inches may be significant extracts from r cks containing predominantly assemblage b show reduced odd preference a full profile of normal alkanes and conspicuous occurrence of isoprenoids including pristane and phytane these samples from iowa are representative of middle ordovician source rocks found in most paleozoic basins of north america as well as baltic europe and australia therefore the conclusions drawn from these middle ordovician rock samples from iowa provide a basis to explain variations in ordovician derived oils found in many other areas

remote and local forcing in the brazil malvinas region origins of the seasonal variability observed in current meter data from the malvinas falkland current are sought in the wind field on both a regional and circumpolar scale a singular value decomposition of the covariance of the fields makes it possible to distinguish between a local and a remote source of variability the local mode is the result of changes in the wind stress curl around 408s causing an annual modulation transverse to the mean path of the current and thus contributes little to the variability in transport it seems likely that the wind stress curl drives the annual excursions of the brazil malvinas front and forces the retroflection of the malvinas current the remote mode features increased transport trailing negative wind stress curl anomalies at drake passage with a lag of 20 30 days repeating this analysis with the winds on a circumpolar domain suggests that this might be the regional manifestation of a more global feature associating globally negative wind stress curl anomalies north of 608s with increased transport this analysis also shows that the malvinas current transport is anticorrelated with the zonal wind stress hence with the antarctic circumpolar current although initially counterintuitive this is confirmed through coherence analyses with bottom pressure measurements at the south of drake passage these results are further assessed using a 5 yr series of transport in the malvinas current derived from topex poseidon altimeter data which is compared with the circumpolar averages of both zonal wind stress and wind stress curl coherences are largest with the wind stress curl at latitudes north of drake passage up to the subtropics and also indicate that it is most influential in the pacific sector it is suggested that the antarctic circumpolar current and the malvinas current respond differently to the wind forcing and that these two modes cohabit at drake passage while the barotropic variations of the former have been shown to respond to the zonally averaged wind stress the fluctuations of the latter at timescales of 100 200 days are more sverdrupian that is sensitive to the wind stress curl lag 20 days explaining why they fluctuate with opposite phase superimposed on this intraseasonal variability at shorter periods 70 days results from baroclinic shelf waves trapped along the edge of the patagonian plateau these propagate from drake passage and may originate from equatorial kelvin waves in the pacific

the relationship of soil organic carbon to 210pbex and 137cs during surface soil erosion in a hillslope forested environment the relationships of erosion induced displaced soil organic carbon soc to discharged 210pbex and 137cs in a hillslope forested area were investigated using runoff plots in three different forest types a significant correlation was found between the displaced soc and the radionuclides in each examined forest type compared with 137cs however the discharge of 210pbex is more closely correlated with the displaced soc and shows a far lower rmse value by approximately a factor of two this finding suggests that 210pbex and soc are more likely than 37cs and soc to move together in the course of soil erosion processes moreover because 137cs was introduced in the 1960s by thermonuclear bomb tests and is being depleted its availability in the environment could be limited in the foreseeable future 210pbex in contrast is continuously replenished from its ubiquitous natural source 222rn in a manner similar to the replenishment of soc from sources consisting of organic material e g litter in the light of this basic understanding our findings provide practical evidence of the potential of 210pbex application for assessing and documenting the water induced distribution of soc on forested hillslopes

identification of a novel c33 n alkylcyclohexane biomarker in permian triassic sediments abstract a c 33 n alkylcyclohexane n heptacosylcyclohexane has been used as a biomarker for oil correlation studies in the perth basin basal triassic western australia for almost two decades but the compound has never been formally identified we now confirm the identification using two perth basin source rock samples by comparison of mass spectra and gas chromatographic retention behaviour on three gc stationary phases with an authentic reference compound recently the c 33 n alkylcyclohexane has been reported to occur in several samples from a key permian triassic section of eastern greenland

distinctive hydrocarbon biomarkers from fossiliferous sediment of the late proterozoic walcott member chuar group grand canyon arizona abundant extractable hydrocarbons in association with well preserved kerogen have been recognised in a dolostone from the chuar group approx 850 ma the biomarkers present include c15 c30 acyclic isoprenoids c26 c28 steranes c27 c35 hopanes and extended tricyclic terpanes among the striking characteristics of the distributions are the dominance of steranes and methyl steranes lacking side chain alkylation and the presence of putative c29 c35 neohopanes and gammacerane the high abundance of steranes is consistent with the presumed eukaryotic affinities of several types of microfossils including chuaria present in associated mudstones this stratum is the oldest in which gammacerane has been found and suggests contributions from protozoa to the depositional environment which appears to have been hypersaline there is a strong correlation between the carbon isotopic composition of the kerogen and that of the various polarity fractions of the bitumens chemical degradation and pyrolysis of the kerogens yielded n alkanes with similar characteristics to the bitumens but there are differences in the patterns of distribution of the acyclic isoprenoid sterane and triterpane biomarkers

bound carboxylic acids in the alberta oil sands abstract the alberta oil sands contain 1 2 organic solvent insoluble organic matter chemisorbed to the inorganic matrix analysis of the monocarboxylic fraction 1 14 of the chemisorbed material has revealed the presence of c12 c32 normal iso anteiso alkenoic acids mono and diunsaturated acids cyclopropylalkanoic and cyclic terpenoid carboxylic acids some of the main components of the acyclic acids were similar to those which have been identified in various petroleums and alberta oil sand bitumens in small concentrations by mackenzie et al advances in organic geochemistry 1981 pp 637 649 wiley heyden 1983 and attributed to bacterial degradation of the oils via the aerobic pathway of biosynthesis the presence of these acids in the chemisorbed fraction and virtual absence in the bitumen lends additional support to earlier proposals that the alberta oil sand bitumens have undergone severe microbial degradation

a note on the barotropic response of sea level to time dependent wind forcing this study examines the extent to which sea level variations at periods between 30 days and 1 year and spatial scales greater than 1000 km can be described by the wind driven linear barotropic vorticity dynamics the topex poseidon altimetric observations of sea level and the wind products of the national meteorological center are used as the database for the study each term of the linear barotropic vorticity equation was evaluated by averaging over regions of 10 10 in most of the open ocean the result of the analysis suggests that the sea level variabilities at the scales considered cannot be fully described by the equation the apparent net vorticity change is more than what can be explained by the local wind stress curl in the few regions where the wind stress curl is strong enough to balance the vorticity budget predominantly in the northeast pacific and the southeast pacific the balance is basically achieved in terms of the time dependent topographic sverdrup relation namely the balance between the advection of the planetary vorticity plus the topography induced vorticity and the forcing by the wind stress curl

the barotropic electromagnetic and pressure experiment 1 barotropic current response to atmospheric forcing during 1986 1987 an array of horizontal electrometers which measure the subinertial barotropic velocity was deployed for 11 months in the central north pacific to study atmospherically forced motions in a low eddy kinetic energy region significant coherence is found to be ubiquitous between the barotropic velocity and one or more surface atmospheric variables over the north pacific the maximum squared coherence between currents and wind stress curl at all periods greater than 3 days is typically 0 6 rarely below 0 4 and occasionally above 0 8 and is dominantly nonlocal although local coherence is seen at some sites especially at the shorter periods both the coherence and the intersite pattern similarity are strongest at the periods of relative maxima in the barotropic current autospectra e g at 6 8 10 14 and 20 50 days the locations at which the wind stress curl forces the motions at each site and for each period have been determined while there is substantial intersite variability some of the observed patterns of squared coherence over the north pacific are very similar to those predicted by simple linear smooth bottomed quasi geostrophic models of atmospherically forced barotropic currents the forcing location is occasionally found to be the same spot for all oceanic instruments especially at the autospectral maxima in barotropic current more commonly distinct forcing locations are found for each instrument even when closely spaced suggesting topographic influence in other cases multiple forcing locations are implicated for the motions at a single station all of this site and period dependent variability of the forcing location is incompatible with the simple models and is due either to the known spatial inhomogeneity of the curl forcing field or to topographic effects the importance of the former is emphasized using simple arguments based on analytic transfer functions between the atmospheric and oceanic variables and on observed wavenumber spectra for wind stress curl quantitative assessment of topographic effects must await suitable numerical models in addition maximum likelihood wavenumber spectra of the barotropic currents have been estimated in those bands with an adequate number of coherent sensors the wavenumbers at the spectral peaks are compatible with the dispersion relation for rossby waves modified by the observed large scale linearly sloping topography which shoals to the northeast the observed group velocities are in general quite consistent with the inferred forcing locations based on the ocean atmosphere coherences

asphalts oils and bituminous rocks from the dead sea area a geochemical correlation study oils and asphalts gilsonite from the dead sea area israel were characterized by bulk composition specific c15 hydrocarbons n alkanes isoprenoids steranes triterpanes and aromatics including sulfur compounds and light hydrocarbons c2 to c8 molecular range these indicators complemented by literature data sulfur content sulfur isotope composition and distribution of petroporphyrins define the oils and asphalts as belonging to a single geochemical province the geochemical characteristics suggest a source material of bacterially reworked algae and a source rock poor in clay minerals probably a calcareous rock calcareous bituminous rocks of the campanian maestrichtian ghareb formation are exposed on the margin of the dead sea graben on downwarped blocks and they probably extend under the thick graben fill the agreement of the geochemical indicators suggests that these bituminous rocks are a potential source of the asphalts and oils in the dead sea area differences between the various types of hydrocarbon occurrences are due to a combination of several effects such as variations in source material the thermal history of the different downwarped blocks water washing and biodegradation the distribution characteristics of hydrocarbons c6 to c35 and c2 to c8 is sensitive to biodegradation and or water washing the aromatic fractions except very soluble compounds like benzene toluene etc are less affected by these processes and record the variability due to source and possibly thermal history the interpretation of the triterpane and sterane distribution corroborates that of other hydrocarbons with respect to maturation and type of source rock differences in maturation are pronounced the bituminous rocks and asphalts are immature and the oils are derived from source rocks in an initial stage of petroleum generation

characterisation of fluid inclusion oil in a mid proterozoic sandstone and dolerite roper superbasin australia detailed geochemical analysis has been carried out on fluid inclusion oils trapped for over 1 billion years in the roper superbasin northern australia in two different geological settings in healed microfractures in a quartz arenite and within partially altered plagioclase laths in a dolerite sill the oil inclusions and co occurring solid bitumens record multiple oil migration events postdating an intrusive episode ca 1300 ma most likely during neoproterozoic basin inversion solid bitumen represents the oldest migration event and occurs in secondary pore space within the bessie creek sandstone and in veins cross cutting the dolerite sill it is interpreted to represent thermally altered oil that may have at least partly been generated by contact metamorphism near the igneous intrusion inclusion oils in both the dolerite feldspar and in the transgranular fractures in the bessie creek sandstone are pristine nonbiodegraded fluids with a great similarity to other bitumens oils and sediment extracts from the roper superbasin biomarkers indicate that the oils were mainly sourced from prokaryotic cyanobacterial organic matter with a small contribution from eukaryotes based on migration distance organic richness geochemistry and similarity of source rock maturity the velkerri formation which directly overlies the dolerite sill and the bessie creek sandstone is the most likely source rock for the higher molecular weight hydrocarbons preserved in the fluid inclusion oils geochemical data indicate that the oil inclusions in clusters in albitised zones of labradorite crystals in the dolerite matrix represent a different migration event from oil inclusions in transcrystalline fractures in vein calcite in the dolerite sill and in transgranular fractures in quartz in the bessie creek sandstone the bessie creek sandstone fluid inclusion oil was generated in the peak to late oil window 0 9 1 0 vre the higher molecular weight c13 proportion of the dolerite feldspar fluid inclusion oil is of lower maturity 0 8 vre than the same molecular weigh range fluid in the bessie creek sandstone fluid inclusion oil both of these oils were most likely generated in the overlying velkerri formation however the volumetrically dominant low molecular weight hydrocarbons in the dolerite feldspar fluid inclusion oils have a higher maturity 1 3 vre and may have been generated from the deeper ca 1600 ma barney creek formation in the underlying mcarthur group this study shows that oil trapped in fluid inclusions has a greater potential to preserve pristine organic geochemical information than porosity bound oils and dispersed kerogen if oil inclusions occur in sufficient abundance the analysis of these tiny oil encapsulations is technically feasible and can give valuable information on the composition of the earth s early biosphere and precambrian petroleum systems

hydrocarbon biomarkers from ordovician sediments and the fossil alga gloeocapsomorpha prisca zalessky 1917 numerous ordovician oils worldwide are known to show unusual and distinctive distributions of hydrocarbons which it has been suggested are derived from a unique benthonic mat forming non photosynthetic prokaryotic organism gloeocapsomorpha prisca zalessky 1917 which is the major contributor of organic matter organic matter rich sediments from the canning and amadeus basins of australia known to contain g prisca fossils and to have the characteristic predominance of odd carbon number c13 c19 n alkanes were investigated to determine other hydrocarbon distributions sediments from both basins contained abundant n alkylcyclohexanes with odd carbon number predominance c13 c19 and methyl n alkylcyclohexanes c14 c20 which in immature sediments showed an even carbon number predominance the isomer distribution of these latter compounds was determined by direct comparison with synthetic standards the sediments from both basins also contained very similar distributions of steranes and pentacyclic triterpanes and the derived kerogens had a characteristically light carbon isotope signature pyrolysis of a g prisca rich kerogen yielded a hydrocarbon mixture with a similar composition to the sediment extract except that there was a marked increase in the relative abundance of pristane phytane alkylcyclohexanes steranes and hopanes relative to n alkanes we argue on the basis of the geological geochemical and palynological data that g prisca was probably planktonic photosynthetic and very possibly eukaryotic and that the striking character of ordovician oils and sediments derive from bacterial and other diagenetic imprints superimposed on the primary signature of this organism

geochemistry of oil in fluid inclusions in a middle proterozoic igneous intrusion implications for the source of hydrocarbons in crystalline rocks abstract the ca 1280 ma dolerite sill within the mesoproterozoic roper group in the roper superbasin australia contains evidence for at least two episodes of hydrocarbon migration represented respectively by solid bitumen with a ketone rich extract and a mixture of a high maturity gas condensate and a lower maturity oil within oil bearing fluid inclusions the ketone isomers are formed by flash pyrolysis of kerogen during the intrusion of the dolerite sill org geochem 21 1994 829 and represent the first and oldest phase of hydrocarbon migration the gas condensate and oil were subsequently trapped as a mixture within fluid inclusions at diagenetic temperatures and pressures of around 110 c and 250 bars significantly after cooling of the sill and likely during the neoproterozoic reactivation of the roper superbasin either 1 these fluids migrated together and mixed in the reservoir or 2 an earlier oil charge was flushed by a later condensate charge and the oil condensate mixture was trapped within single fluid inclusions oil inclusions occur chiefly within albitised zones of labradorite laths within the dolerite matrix and within transcrystalline microfractures cutting vein calcite and rarely vein quartz oil inclusions trapped in the vein calcite are accompanied by hypersaline ca mg brines gas chromatography mass spectrometry of oil extracted from inclusions within the dolerite matrix shows that the oil is non biodegraded and was therefore trapped relatively quickly within the host minerals trace amounts of biomarkers indicate that the inclusion oil is of a biogenic origin and excludes any abiotic processes that are apparent sources of hydrocarbons in many crystalline rocks monomethylalkanes pentacyclic terpanes chiefly comprising hopanes and diahopanes and very low concentrations of steranes and diasteranes indicate input from cyanobacterial organic matter with a minor contribution from eukaryotes the hydrocarbons are likely derived from proterozoic source rocks such as the directly overlying velkerri formation and or the underlying barney creek formation from the mcarthur group the study has implications for the source of hydrocarbons in non sedimentary rocks and suggests that fluid inclusions can be used not only to distinguish between biogenic and abiogenic sources of hydrocarbons but also to provide critical information about the composition of the biomass fluid migration events and conditions under which hydrocarbons in different geological settings are trapped

biological markers in bitumens and pyrolyzates of upper cretaceous bituminous chalks from the ghareb formation israel abstract the sterane and triterpane distributions of three bituminous chalks from the upper cretaceous ghareb formation israel were investigated both in the original extractable bitumens and in extracts obtained after pyrolysis of whole rock and isolated kerogen samples at 450 c pyrolysis was performed in a closed system under hydrous whole rock and anhydrous conditions isolated kerogens the carbon number distributions of steranes and triterpanes differ significantly between original bitumen and pyrolyzates unlike the bitumens in which diasteranes were not detected the anhydrous pyrolyzates contain small amounts of diasteranes the presence of water during pyrolysis leads to an increase of sterane isomerization the abundant formation of diasteranes and an increase of the 18 h trisnorneohopane 17 h trisnorhopane ratio sterane isomerization maturation parameters show a closer match between original bitumen and pyrolyzates after pyrolysis in a closed system when compared with an open system

an overview of pre devonian petroleum systems unique characteristics and elevated risks abstract the radiation of land plants at the onset of the devonian resulted in a change in the character of available biomass which in turn introduced changes to the nature of petroleum systems this study examines the nature of pre devonian petroleum systems prior to this significant evolutionary event conventional hydrocarbon resources have been associated with pre devonian petroleum systems across the globe including the neoproterozoic infracambrian huqf supergroup of the oman basin the riphean vendian sequences of east siberia the cambrian of the murzuq basin the ordovician of the tarim basin and the silurian qusaiba of saudi arabia although individual accumulations can be quite significant e g hassi messaoud has ultimate recoverable reserves of 10 billion barrels the relative importance of pre devonian derived oils is thought to be limited compared to the global conventional resource base with growing interest in unconventional resources the relative importance of these systems is expected to increase as resource plays such as the ordovician utica shale of the appalachian basin the cambrian of china and possibly the silurian of central and eastern europe develop the advanced ages of these systems result in some unique properties and amplify risks that exist in younger petroleum systems differences in the nature of the biomass contributing to pre devonian source rocks may give rise to oils that display unique geochemical characteristics for example there are some precambrian oils where c 29 steranes dominate even though land plants were absent there are also ordovician source rocks dominated by gloeocapsamorpha prisca a primitive prokaryote which yield oils containing limited amounts of c 20 components and nearly lack pristane and phytane the potential for unconventional reservoirs in pre devonian systems may also be highly dependent upon the age of the system as biological evolution influences the availability and nature of biogenic silica an important factor controlling brittleness and fracability literature has shown that biogenic silica from different sources displays varying degrees of resistance to diagenesis which allows the formation of a silica network and influences brittleness for example radiolaria present during the cambrian are more resistant to diagenesis than diatoms which did not evolve until the jurassic risks associated with preservation of hydrocarbons are also amplified in pre devonian petroleum systems many such systems have been exposed to significant thermal stresses resulting in the cracking of oil and wet gas others have had complex tectonic histories potentially resulting in the breaching of seals or changes in pvt conditions that can result in gas loss gas loss may also occur through diffusion from these older reservoirs as a result of long residence times

quantifying the north pacific silica plume 1 new hydrostations plus a comprehensive compilation of existing data have allowed us to characterize the dissolved silica plume located at midwater depths in the north pacific the north pacific silica plume is a global scale anomaly extending from the north american continental margin in the east to beyond the hawaii emperor seamount chain in the west inventory of the plume between 2000 and 3000 m depth indicates that it contains 164 tmols 164 1012 mols of anomalous dissolved silica and is maintained by a horizontal flux of approximately 1 5 tmols yr from the east the source region of this plume has been previously suggested to be cascadia basin in the ne pacific biochemical and geothermal processes within this small region can produce approximately one third of the required flux but the majority of silica contained within the north pacific plume may originate in crustal fluid venting from the warm upper basement aquifer that underlies the easternmost pacific plate

hydrocarbon shows and petroleum source rocks in sediments as old as 1 7 109 years we report the discovery of indigenous live oil in 1 4 gyr old rocks in the mcarthur basin of northern australia previously reported occurrences of indigenous precambrian oil are 1 gyr old1 5 potential petroleum source rocks in the mcarthur basin range in age from 1 4 to 1 7 gyr and were deposited in marine and lacustrine environments in parts of the basin they have been buried sufficiently deeply to have generated hydrocarbons they span the period corresponding to the appearance of eukaryotic organisms and because of their low degree of thermal alteration they provide a valuable resource for the study of primitive biota through their hydrocarbon biomarkers the hydrocarbon composition of the oil is consistent with a derivation from organic matter of prokaryotic origin these results show that exploration of previously ignored mid proterozoic sediments may lead to the discovery of new reserves of oil

hydrocarbon biomarkers in the topla mežica zinc lead deposits northern karavanke drau range slovenia paleoenvironment at the site of ore formation the mississippi valley type zinc and lead deposits at topla 250 150 metric tons t of ore grading 10 wt zn and 3 3 wt pb and me ica 19 million metric tons mt of ore grading 5 3 wt pb and 2 7 wt zn occur within the middle to upper triassic platform carbonate rocks of the northern karavanke drau range geotectonic units of the eastern alps slovenia the ore and host rocks of these deposits have been investigated by a combination of inorganic and organic geochemical methods to determine major trace and rare earth element ree concentrations hydrocarbon distribution and stable isotope ratios of carbonates kerogen extractable organic matter and individual hydrocarbons these data combined with sedimentological evidence provide insight into the paleoenvironmental conditions at the site of ore formation the carbonate isotope composition the ree patterns and the distribution of hydrocarbon biomarkers normal alkanes and steranes suggest a marine depositional environment at topla a relatively high concentration of redox sensitive trace elements v mo u in the host dolostones and ree patterns parallel to that of the north american shale composite suggest that sediments were deposited in a reducing environment anoxic conditions enhanced the preservation of organic matter and resulted in relatively higher total organic carbon contents up to 0 4 wt the isotopic composition of the kerogen 13 c kerogen 29 4 to 25 0 15 n kerogen 13 6 to 6 8 suggests that marine algae and or bacteria were the main source of organic carbon with a very minor contribution from detrital continental plants and a varying degree of alteration extractable organic matter from topla ore is generally depleted in 13 c compared to the associated kerogen which is consistent with an indigenous source of the bitumens the mineralization correlates with 15 n kerogen values around 0 per mil 13c depleted kerogen 13c enriched n heptadecane and relatively high concentrations of bacterial hydrocarbon biomarkers indicating a high cyanobacterial biomass at the site of ore formation abundant dissimilatory sulfate reducing bacteria feeding on the cyanobacterial remains led to accumulation of biogenic h 2 s in the pore water of the sediments this biogenic h 2 s was mainly incorporated into sedimentary organic matter and diagenetic pyrite higher bacterial activity at the ore site also is indicated by specific concentration ratios of hydrocarbons which are roughly correlated with total pb plus zn contents this correlation is consistent with mixing of hydrothermal metal rich fluids and local bacteriogenic sulfide sulfur the new geochemical data provide supporting evidence that topla is a low temperature mississippi valley type deposit formed in an anoxic supratidal saline to hypersaline environment a laminated cyanobacterial mat with abundant sulfate reducing bacteria was the main site of sulfate reduction

biomarker and isotopic signatures of an early cambrian lagerstatte in the stansbury basin south australia abstract the lower cambrian series 2 emu bay shale biota found at big gully on the north coast of kangaroo island south australia is by far the richest burgess shale type bst fauna in the southern hemisphere while the trace element geochemistry of the host shale shows it accumulated beneath an oxic water column this appears difficult to reconcile with the exceptional preservation of organs such as gut glands muscles and eyes in some of its fauna micro scale sealed vessel mssv pyrolysis of kerogen isolated from a solvent extracted sample of fossiliferous emu bay shale provided independent confirmation of its redox status and also implicated cyanobacteria in the preservation of its fauna thermal extraction and pyrolysis each yielded alkanes displaying a low ratio of pristane to phytane pr ph 1 and n alkanes with a marked odd even predominance in the 20 range the latter molecular signature is diagnostic of gloeocapsomorpha prisca and is the first indication that mats of this or a similar coccoid cyanobacterium were involved in the taphonomy of a bst deposit hopanes including 2 methylhopanes are far more abundant than steranes and the shale s bulk organic matter has 13 c values in the range 32 to 28 providing further evidence of the cyanobacterial affinity of its microbial biomass thus mat forming cyanophytes rather than sulfur oxidising bacteria may have played a key role in maintaining a sharp redox boundary at the sediment water interface during deposition of the emu bay shale lagerstatte thereby enabling the survival of soft body parts within its fossil fauna for long enough to permit inorganic replication of their fine detail during late diagenesis

extent and persistence of photic zone euxinia in middle late devonian seas insights from the canning basin and implications for petroleum source rock formation abstract late devonian mass extinctions attributed to extensive anoxia and or euxinia of the oceans are associated with widespread deposition of organic rich shales also in the epeiric waters of the canning basin western australia photic zone euxinia pze prevailed during the givetian frasnian with geochemical evidence for pze on the northern lennard shelf and southern barbwire terrace margins of the fitzroy trough on the lennard shelf shales record episodic pulses of pze associated with high algal activity due to enhanced nutrient supply whereas a restricted marine setting on the barbwire terrace is thought to be the main driver for the development of persistent pze and associated bacterial predominance structural evidence indicates that the fitzroy trough was a confined basin during the late devonian with the possibility of limited ocean circulation widespread pze is expected to have developed in the poorly mixed water column if the basin received sufficient nutrient supply for enhanced primary production notwithstanding the presence of anoxia during deposition of potential source rocks only two small devonian sourced oil fields and numerous oil shows have been found in the canning basin biomarker assemblages show that the oils produced from the lennard shelf fields i e blina 1 blina 4 and janpam north 1 have substantially different molecular compositions to the minor oil recovered from mirbelia 1 on the barbwire terrace a correlation was established between the lennard shelf oils and rock extracts from the gogo formation at blina 1 and mcwhae ridge 1 based on their hopane sterane and carotenoids abundances a definitive source correlation was not obtained for the mirbelia 1 oil but it did show some genetic affinity to the givetian frasnian extracts from the barbwire terrace suggesting that local source rocks are developed in the region

diagenesis of free and bound lipids in terrestrial detritus deposited in a lacustrine sediment recent sediments from an oligotrophic lake loch clair having uniform organic input for 2000 yr show changes in lipid abundance and composition with increasing depth attributed to diagenesis stability of free lipids decreases in the order n alkanes alkan 2 ones sterols n alkanoic acids n alkanols n alkenoic acids diagenetic loss of shorter chain homologues is complete within 400 yr stabilisation of bound relative to free lipids increases the proportion of the former with sediment age and reduces loss of shorter chain bound homologues in an eutrophic lake cross mere shorter chain free and bound sedimentary lipids show increased abundance compared with loch clair the relative importance of higher input of shorter chain lipids derived from aquatic detritus and slower initial diagenesis due to the anoxic hypolimnion as causative factors for this difference between lake types cannot yet be assessed

structure and origin of terpenoid hydrocarbons in some german coals abstract hydrocarbon extracts of coal samples from major coal fields in west germany have been investigated by gas chromatography mass spectrometry gc ms the samples are of carboniferous and tertiary age and derive from limnic and paralic environments the saar district the ruhr area and the lower rhine basin differences in facies maturity and age reflected in the distribution patterns of the extracted alkylcyclohexanes an unexpected occurrence of cyclic diterpenoid hydrocarbons in some samples of carboniferous age has been found the tetracyclic compounds mainly show phyllocladane type structures and can serve as source indicators hydrocarbons obtained from chemical degradation of the macromolecular material of the samples also revealed phyllocladane type compounds which are normally associated to resins of modern and extinct familes of conifers origin and structural variations of this class of hydrocarbons are discussed in terms of maturity and palaeobotanical implications

truncation and accretion of soil profiles on coastal plain croplands implications for sediment redistribution soil stratigraphy and morphology in a small agricultural watershed on the coastal plain at clayroot north carolina indicate long term decadal scale patterns of the redistribution of sediment the most dramatic truncation of the soil profile occurs on convex upper slopes and suggests tillage and aeolian erosion as the major processes of soil loss thicker soils immediately downslope from convexities are consistent with redistribution by tillage but significant aeolian soil loss also occurs from some fields thinner apparently truncated soils were also associated with relatively steeper lower slope areas where contemporary rilling was observed the presence of thicker cumulic soils at toeslopes where small fans are observed at rill termini and about a half meter of alluvium in drainage ditches indicates that water erosion is also quite prominent distinctive soil stratigraphy is found in areas of aeolian deposition where podzolization in sandy surface deposits has created compound soil profiles on convex slopes tillage and wind erosion result in net soil loss with the former dominating on wetter soils and when plowing occurs and aeolian processes dominating on drier hilltops and when no till or minimum tillage practices are followed soils are thicker immediately downslope from convexities with thinner soils and rill erosion on lower slopes thickened soils and colluvial deposition in the form of thin fan deposits occur at toeslopes and in depressions the borders of fields often have thicker soils because of aeolian deposition water wind and tillage processes are all significant in soil redistribution at the clayroot site with relative importance in space and time controlled by topography soil properties seasonal moisture and vegetative cover and tillage practices

spatial and temporal characteristics of the wind forcing of the bering sea abstract the surface wind stress over the bering sea is estimated for the period 1946 90 from sea level pressure analyses empirical relationships between the geostrophic wind and the surface wind and a bulk aerodynamic formula the focus is on the propagation and variability of the stress and the curl of the stress as a function of frequency the stress at high frequencies 0 1 cpd is dominated by northward and eastward propagating disturbances with mean wavelengths of 2500 and 10 000 km respectively at periods of 10 100 days the mean propagation is near zero there are however significant interannual variations in the zonal propagation wind driven ocean transports estimated by the sverdrup method for the deep bering basin account for 6 sv or roughly one half of the observed transport within the western boundary current along the kamchatka peninsula a low pass filtered retaining periods greater than 18 months time series of the sverdrup transport exhibits a standard deviation of 25 of th

organic geochemistry across the permian triassic transition at the idrijca valley western slovenia abstract bulk and molecular stable c isotopic compositions and biomarker distributions provide evidence for a diverse community of algal and bacterial organisms in the sedimentary organic matter of a carbonate section throughout the permian triassic p tr transition at the idrijca valley western slovenia the input of algae and bacteria in all the upper permian and lower scythian samples is represented by the predominance of c15 c22 n alkanes odd c number alkylcyclohexanes c27 steranes and substantial contents of c21 c30 acyclic isoprenoids the occurrence of odd long chain n alkanes c22 c30 and c29 steranes in all the samples indicate a contribution of continental material the decrease of corg and ccarb contents increase of rock eval oxygen indices and 13c enrichment of the kerogen suggest a decrease in anoxia of the uppermost permian bottom water the predominance of odd c number alkylcycloalkanes c27 steranes and c17 n alkanes with 13c values 30 and 13c enrichment of the kerogens in the lowermost scythian samples are evidence of greater algal productivity this increased productivity was probably sustained by a high nutrient availability and changes of dissolved co2 speciation associated to the earliest triassic transgression a decrease of corg content in the uppermost scythian samples associated to a 13c depletetion in the carbonates up to 4 and individual n alkanes up to 3 4 compared to the upper permian samples indicate lowering of the primary productivity algae cyanobacteria and or higher degradation of the organic matter

black shale xenolith in a jurassic cretaceous kimberlite and organic rich upper ordovician shale on baffin island canada a comparison of their organic matter abstract rock eval pyrolysis and molecular organic geochemical analyses as well as organic petrographic observations were carried out on a rare black shale xenolith core drilled from a late jurassic early cretaceous kimberlite on the hall peninsula in southern baffin island canada the results are compared with those of outcrop shale samples from the upper ordovician amadjuak formation the only organic rich shale deposit discovered so far in the region the shale xenolith is found to be organic rich and thermally mature at the stage of peak oil generation and contain type ii organic matter similar to that of the immature amadjuak shale discounting the differing thermal maturation effect similar depositional environments and original organic inputs are suggested for both the shale xenolith and the upper ordovician shale based on their bulk molecular and isotopic signatures as well as organic maceral assemblages the present study cannot exclude the possibility of the shale xenolith being originated from an organic rich lower silurian deposit as suggested by previous re os isotope dating study it is clear however that depending on their areal distribution and thickness the lithostratigraphic unit from which the organic rich black shale xenolith is derived would make an excellent petroleum source rock in the study area

molecular and stable carbon isotopic composition of monomethylalkanes from one oil sand sample source implications abstract unusually abundant long chain monomethylalkanes mmas c 25 c 36 and their short chain homologues c 14 c 22 have been tentatively identified in a late triassic oil sand sample from the lunnan oilfield tarim basin nw china molecular distributions and stable carbon isotopic compositions of these compounds have been determined to investigate their bio and or geosynthetic sources the results show that the most abundant isomers of short chain mmas were 4 methyl m z 70 5 methyl m z 84 6 methyl m z 98 and 7 methyl m z 112 alkanes whereas in long chain mmas there is a clear predominance of the 9 methyl and 10 methyl isomers combined with the compound specific stable carbon isotopic analysis it is concluded that short chain mmas and long chain mmas must have different sources the similar isotopic compositions of mmas and n alkanes in this sample suggest that they may share the same sources the short chain mmas as previously suggested are probably related to a cyanobacterial origin while the long chain mmas may be mainly associated with microorganisms or heterotrophic bacteria rather than cyanobacteria

slope curvature influence on soil erosion and deposition processes sediment water quality problems are not necessarily the direct result of erosion from the most intense soil erosion areas a study of within basin variability of the sediment delivery processes is needed to identify areas where the most effective soil conservation strategies should focus in this paper the sediment delivery processes is examined along the hydraulic path from sediment source areas to the nearest stream reach the effects of shape convex concave and uniform of the hydraulic path are modeled using a power equation for slope profile and revised universal soil loss equation rusle with two different expressions of the topographic factors a criterion is proposed for the erosion active slope length i e the slope length in which no deposition processes occur then using the continuity equation for sediment transport a factor is deduced to correct the topographic factors of rusle and those proposed by moore and burch 1986 depending on slope curvature finally two relationships for correcting the topographic factors for an irregular slope are experimentally tested comparing the calculated sediment yields with net soil erosion values estimated by the proportional method of martz and de jong 1987 and cesium 137 data available from a sicilian basin

light hydrocarbon gasoline range parameter refinement of biomarker based oil oil correlation studies an example from williston basin abstract we evaluated geochemical compositions of 189 crude oils produced from paleozoic reservoirs across the williston basin emphasis is placed on compositional variations in the gasoline range i c 5 h 12 n c 8 h 18 to verify the biomarker based classification of oil families the oils belong to four distinct compositional oil families a b c and d broadly confined to specific stratigraphic intervals the unique character of each oil family evident from their n alkane and biomarker signatures is supported by distinctive gasoline range characteristics in general and c 7 mango parameters in particular an invariance in the k1 parameter among oils from a single compositional group is observed for most of the oils the k1 ratio although relatively constant within each suite of oils is different for each oil family clearly indicating their compositional distinction other mango parameters n2 p2 p3 show a similar reflection of the oil families however while c 7 parameters provide excellent evidence for distinct familial association of oils from families a b and d family c often overlaps with the latter two families perhaps indicating greater genetic and source heterogeneity in the family c oils nevertheless differences in the gasoline range composition suggest that the existing biomarker based classification of oil families can be more universally applied throughout the entire williston basin moreover because the light hydrocarbon parameters prove very useful in refining oil oil correlations routine gasoline range analysis shows good potential as a supplementary component in geochemical correlation of crude oils especially when high levels of thermal maturity decrease the usefulness of biomarker compounds

a local time dependent sverdrup balance in the eastern north pacific ocean direct observations of the dynamic balance between time dependent winds and deep ocean currents are described for the eastern north pacific ocean at 42 n 152 w currents from 150 to 4000 meters below the surface at frequencies from 0 01 to 0 1 cycle per day are significantly correlated with the wind stress curl derived from u s navy operational wind fields the horizontal currents are depth independent below 300 meters and they flow parallel to the potential vorticity gradient derived from the earth9s rotation and the large scale bottom topography these characteristics are expected for such periodic motions with horizontal scales larger than 500 kilometers and represent a generalized sverdrup balance between the atmospheric forcing and the oceanic response

chemical and carbon isotopic evolution of hydrocarbons during prograde metamorphism from 100 c to 550 c case study in the liassic black shale formation of central swiss alps abstract hydrocarbon distributions and stable isotope ratios of carbonates 13ccar 18ocar kerogen 13cker extractable organic matter 13ceom and individual hydrocarbons of liassic black shale samples from a prograde metamorphic sequence in the swiss alps were used to identify the major organic reactions with increasing metamorphic grade the studied samples range from the diagenetic zone 17 n alkanes suggests the occurrence of cracking reactions of high molecular weight compounds the isotopically heavier up to 5 6 c 13 n alkanes with metamorphism suggests progressive thermal release of kerogen linked fatty acid precursors and degradation of n alkanes changes of the steroid and terpenoid distributions are clearly related to increasing metamorphic temperatures the absence of 18 h 22 29 30 trisnorneohopane ts the occurrence of 17 h trisnorhopane 17 h 21 h hopanes in the c29 to c31 range and 5 h 14 h 17 h 20r c27 c29 steranes in the low diagenetic samples the occurrence of specific hydrocarbons e g n alkylcyclopentanes cadalene hydrogenated aromatic compounds in metamorphic samples points to kerogen degradation reactions most probably occurring in the presence of water and under reducing conditions the changes of hydrocarbon distributions and carbon isotopic compositions of n alkanes related to metamorphism suggest that the organic geochemistry may help to evaluate the lowest grades of prograde metamorphism

distribution of caesium 137 in soils across a hillslope hollow the distribution of soil 137cs in relation to selected soil and landform properties was studied across a 16 ha hillslope hollow in the hunter valley new south wales australia the hillslope was used as grazing for cattle caesium 137 was not significantly related to the amount of sand silt or clay the bulk density the organic matter content the slope angle or the relative distance downslope however 137cs was significantly related to the thickness of the soil a horizon spatial variations in 137cs were compared with topographic units and a six element hillslope model but there was little correspondence it was thought that the effects of microtopography could have masked potential interrelationships between 137cs and broader scale landform parameters

source rock characterization and oil to source rock correlation of a cambrian ordovician fold and thrust belt petroleum system western newfoundland abstract in this study we use biomarker and isotope data to address the complexities of petroleum system analysis in fold thrust systems specifically related to hydrocarbon generation and migration such as variable thermal maturities of source rocks complex migration pathways and mixing source rocks extracts and oil samples are taken from paleozoic rocks along the appalachian structural front in western newfoundland oil seeps along this fold and thrust belt have motivated episodic exploration efforts over the last 150 years however economic development has been unsuccessful to date in part because of the complex nature of oil to source relationships pyrolysis analyses identify promising source intervals in lower ordovician floian formations with an excellent source potential containing type i ii organic matter toc up to 9 35 hi up to 840 a second good source interval identified within the late cambrian furongian continental slope and rise sediments contains type ii iii organic matter toc up to 2 34 hi 380 source rock samples from outcrops are marginally mature to mature with tmax values between 436 and 447 geochemical analyses of source rock extract imply a clastic shale dominated source rock with a minor contribution from carbonate source rocks chemometric analyses yield 3 extract groups groups 1 and 2 contain lower ordovician samples with organic matter derived from oxidized micro plankton with varying amounts of gleocapsomorpha prisca extract group 3 originates from cambrian samples and shows evidence of a bacterial derived organic matter similar genetic relationships among 10 oil samples from natural oil seeps and abandoned well sites are indicated by high resolution biomarker analyses seven oil samples originated from ordovician source rocks that produced high api oils with low bisnorhopane hopane tricyclic hopane ratios and high sterane concentrations supporting interpretation of a source containing algal derived organic matter three oils originated from cambrian shales these high api oils show high bisnorhopane hopane and tricyclic hopane ratios low sterane concentrations and low carbon isotope values all indicative of organic matter derived from bacteria generated over a wide range of maturities 0 98 1 26 ro thermal maturity sensitive biomarkers and naphthalene ratios show that source rocks generated oils with a wide range of maturities related to their dipping character in the imbricated thrust stack the cambrian source generated oils that locally experienced secondary cracking during acadian inversion whereas the ordovician source generated oil with low maturities after the acadian inversion oil operaters exploring fold and thrust belt petroleum systems may expect extreme changes of oil properties for example api gravity in spacially restricted areas

motional induction effect on the planetary scale geoelectric potential in the eastern north pacific geoelectric potentials induced by seawater motion on a planetary scale were studied using voltage differences measured on the hawaii 1 haw 1 submarine cable between hanauma bay oahu hawaii and point arena california the motionally induced field was extracted from a 3 6 year segment of the haw 1 voltage by cancelling the component that is coherent with the externally produced geomagnetic field at honolulu the corrected voltage shows significant coherence with atmospheric variables wind stress curl wind stress and surface pressure estimated from the european centre for medium range weather forecasts product at points throughout the pacific basin at periods from 5 to 133 days this suggests that the voltage reflects regional to basin wide depth averaged barotropic water currents that are directly wind driven contour maps of the squared coherence reveal that 1 peak coherence as large as 0 6 0 8 is seen at points both near the cable and nonlocally 2 higher coherence is seen at periods where the cable voltage power spectrum peaks and 3 spatial patterns of the coherence vary with period comparison of power spectra or coherence maps for individual years shows that the wind driven flow fluctuates temporally owing to long term variations of the wind field the main features of these observations are consistent with those from point electric field measurements suggesting that planetary scale voltages measured with cables can serve as a useful tool to monitor large scale water currents at long periods

molecular indicators of redox and marine photoautotroph composition in the late middle ordovician of iowa u s a abstract saturated and aromatic hydrocarbons were used to evaluate depositional redox conditions and marine photoautotroph contributions to middle caradocian strata of the central united states ia at the base of the spechts ferry member of the decorah formation 13c enriched aryl isoprenoids derivatives of green sulfur bacteria become abundant indicating the development of photic zone anoxia this is coincident with the disappearance of the organic walled microfossil gloeocapsomorpha prisca and a marked decrease in the relative abundances of cyanobacterial biomarkers the development of dysoxic to anoxic conditions and or associated changes in basin circulation potentially affected the distributions and abundances of these organisms in the overlying guttenberg member g prisca derived organic matter becomes dominant but relative cyanobacteria abundances remain low in addition the percentage total organic carbon is greater than 20 even though selected biomarker ratios pristane phytane ratios greater than 3 and homohopane indices less than 0 5 and the presence of bioturbation indicate that bottom waters were oxygenated it is suggested that deposition of g prisca affected both organic matter preservation and depositional redox conditions observed variations in redox indicators and marine photoautotroph contributions are associated with changes in siliciclastic deposition reported macrofauna turnover and with evidence for oceanic cooling and a change in circulation patterns documented in the eastern united states

observations of wind forced deep ocean currents in the north pacific this study examines the atmospheric response of the deep ocean using 200 instrument years of moored current measurements from across the breadth of the mid latitude north pacific we have found evidence of a seasonal modulation in the ocean eddy kinetic energy beneath the thermocline at several locations north of 35 n this modulation is often in phase with the local atmospheric forcing function at frequencies between 0 1 and 0 01 cpd correlations between the local wind stress curl and the deep currents have been found for a few locations the local forced response is parallel to the potential vorticity gradient f h and consistent in amplitude with a local topographic sverdrup balance nonlocal forcing in the form of flow along isolines of potential vorticity has been estimated and it is comparable to the observed flow at some locations but the modeled flow is not correlated with the observations throughout the mid latitude north pacific the bottom slope tends to enhance the effect this suggests that topography narrows the available bandwidth for forced barotropic rossby waves facilitating a quasi steady topographic sverdrup response over most of the basin however the enhanced effect reduces the magnitude of the ocean s response to wind forcing nonlocally forced sverdrup currents flow along isolines of f h are the dominant component but are only of the order of 1 cm s 1 locally forced sverdrup currents flow across isolines of f h are typically of the order of 0 1 cm s 1 rms and are not commonly measured hence these wind forced variations are a background level signal in the mid latitude eddy kinetic energy in a few isolated areas the bottom slope reduces the effect in these regions the local sverdrup response is amplified and has been observed

interdecadal variations in the alaska gyre abstract climatic dynamic topography variations in the alaska gyre during the period 1968 1990 are described with an objective analysis of more than 12000 std and xbt stations and coads wind stress data interannual dynamic height and sst variations were correlated and were consistent with recently described large scale climatic shifts in the north pacific the gyre was cantered more to the east circulation appeared stronger and sst was lower during the early to mid 1970s than during the 1980s the aleutian low np and pna indices intensified during the interim but the response did not appear as a gyre spinup instead the associated wind stress anomalies forced a slowly varying dynamic height anomaly across the eastern and northern part of the gyre through ekman convergence which had the effect of displacing the gyre s low somewhat to the wsw in the 1980s the wind curl spectrum was white and the slow oceanic response was modelled as stochastic forced climate variability with a simple first order m

branched alkanes from ancient and modern sediments isomer discrimination by gc ms with multiple reaction monitoring abstract linked scanning of a tandem sector mass spectrometer has been used to identify abundant first field free region ffr1 unimolecular fragmentations in branched and isoprenoid hydrocarbons the most intense structure specific reactions were selected to establish multiple reaction monitoring mrm parameters for gc ms analysis this methodology has been used to study the identity of co eluting and closely eluting hydrocarbon biomarkers from modern and ancient sediments anand from extant micro organisms some sediments of cambrian and proterozoic age have been found to contain suites of monomethylalkanes with all possible isomers present and with little apparent preference for the site of branching

the barotropic response of the subpolar north pacific to stochastic wind forcing in a recent observational study koblinsky et al 1989 attempted to demonstrate that the topographic sverdrup balance can account for mesoscale current fluctuations with periods between 10 and 100 days in the abyssal north pacific however the topographic sverdrup balance proved difficult to verify systematically over the north pacific in this paper the conditions required to obtain the topographic sverdrup balance are investigated through numerical experiments with a stochastically forced barotropic quasi geostrophic numerical model of the subpolar north pacific in the numerical experiments the topographic sverdrup balance emerges from area averages of the terms in the vorticity equation but only for periods longer than about 40 days when the averages are taken over 4 4 region this period increases when averages are taken over progressively smaller regions an examination of vorticity balances at individual points along sections through the model domain indicates that the topographic sverdrup balance is not obtained at individual points even for very long period motions the possibility of verifying topographic sverdrup dynamics with oceanic data is considered it is argued that topographically generated small scales in the velocity field reduce the likelihood that the topographic sverdrup balance can be systematically observed in velocity measurements from individual current meter moorings the results suggest that the vorticity balance is complex and that topographic sverdrup dynamics cannot be expected to provide an adequate explanation for the seasonal modulation of the abyssal eddy kinetic energy that is observed with moored instrumentation in the north pacific

wind forced variability of the deep eastern north pacific observations of seafloor pressure and abyssal currents data from an array of bottom pressure gauges and a string of current meters in the vicinity of 47on 139ow are used to examine the deep ocean variability forced by ocean surface wind stress curl from august 1987 to june 1988 bottom geostrophic currents are computed from the pressure gauge array and these correspond well to the long period directly measured currents at 3000 m the supratidalperiod bottom pressure variations are coherent at 95 confidence with the wind stress curl in period bands of 3 4 days and 15 60 days but removed in distances of 400 and 700 km to the northwest and the southeast respectively a linear two layer hydrodynamic model is used to examine the theoretical forcing produced by random phased surface wind fields for the conditions of the eastern north pacific and the 15 to 60 day period observed response is reproduced credibly to model 3 to 15 day variations more realistic models are required currents are related to surface winds were derived from yearlong current meter records in a cluster of moorings north and east of barbados koblinsky and niiler 1982 showed that significant coherences existed between the 4 to 40 dayperiod east west pulsations of the trade winds r x above barbados and the north south currents v at all depths in the ocean at 15on 54ow the response amplitude of v to r x was depth and period dependent it decreased by a factor of 3 from 150 to 4000 m depths and increased by a factor of 5 from 8 to 40 day periods the interpretation of these data was that the deep ocean forcing was produced by large horizontal scale wind stress curl hereinafter referred to simply as curl due to westward propagating pulses in the trade winds with larger east west than north south scale the amplitude of the deep wind related currents was 1 3 cm s thus deep ocean forcing should be observable in many places where the mesoscale eddy energy is low theoretically wind forced deep ocean motions should depend upon wind stress curl mt iller and frankignoul 1981 using a model of randomly forced linear motions in a stratified infinite flat bottom beta plane ocean computed local coherences and showed that motions across the planetary vorticity gradient should exhibit the strongest coherence with the local wind stress curl niiler and koblinsky 1985 using current meter data demonstrated that such a dynamical link does in fact exist locally at 42on 152ow although at a shorter period than was predicted by milller and frankignoul both the amplitude and the phase of the currents that were forced across the planetary potential vorticity field orf h contours on a 150 km horizontal scale were predicted from the local surface wind stress computed from a similar 150 km scale wind field the 4000 m oscilla

the role of heating winds and topography on sea level changes in the north atlantic seasonal and interannual to decadal variations of large scale altimetric sea surface height ssh owing to surface heating and wind forcing in the presence of topography are investigated using simplified models the dominant forcing mechanisms are time scale dependent on the seasonal time scale locally forced thermosteric height explains most of the ssh variance north of 18 n first mode linear long baroclinic rossby waves forced by changes in the winds and eastern boundary conditions explain most of the variance between 10 n and 15 n and are also important east of greenland on interannual to decadal time scales local thermosteric height remains important at several locations in the middle and high latitudes a topographic sverdrup response explains interannual to decadal ssh between 53 n and 63 n east of greenland farther south the linear rossby wave model explains ssh variations on interannual to decadal time scales between 30 n and 50 n from mid basin to the eastern boundary propagation of the eastern boundary condition into the interior dominates the interannual to decadal ssh signals south of 30 n the effect from nao related heat flux on ssh is small but forcing the topographic sverdrup models with nao regressed winds gives slightly better agreement with the observed ssh in the subpolar gyre on interannual to decadal time scales than using the full winds

quasi geostrophic ocean response to real wind forcing the effects of temporal smoothing abstract a one degree flat bottom eight layer quasi geostrophic model of the north pacific ocean is forced by six different wind stress curl datasets all derived from seven years of twice daily analyses at the european centre for medium range weather forecasts 1980 86 the six datasets with nominal averaging times of 1 2 3 7 14 and 30 days are obtained by carefully filtering in the frequency domain this filtering greatly reduces the variance typically by 90 for 30 day averaging because the wind stress curl spectrum is nearly white in frequency it also smoothes spatially reducing high wavenumber variance to a greater degree than variance near wavenumber zero the climatology of the ecmwf wind stress curl does not show any unexpected differences from climatologies based on historical marine wind observations the wind stress curl is neither temporally nor spatially stationary with the high frequency variance being much larger during the winter season and over the northern half of the north

wind forced intraseasonal sea level variability of the extratropical oceans abstract seven years worth of sea level observations from the topex poseidon altimeters and wind observations from the european remote sensing satellites ers 1 2 scatterometers were used to investigate the dynamics of large scale intraseasonal sea level variability at mid and high latitudes coherent patterns of sea level variability with spatial scales of 1000 km and timescales of 20 days to 1 year are identified in three particular regions the bellingshausen basin west of drake passage the australian antarctic basin and the central north pacific ocean 30 50 n near the date line significant coherence is found between wind stress curl and the sea level variability a simple barotropic vorticity equation in which the time rate of relative vorticity variation is balanced by the wind stress curl and a damping term is used to simulate the sea level anomalies with a significant degree of correlation with the observations although the coherence between the simulation and the observation is signifi

organic geochemical indicators of biological sulphate reduction in early diagenetic znpb mineralization the bois madame deposit gard france abstract at bois madame gard france zn pb s mineralization zn pb 4 occurs in dolomitized kimmeridgian carbonates very near layers which are rich in organic matter of planktonic origin previous geological and geochemical studies have suggested early syn or diagenetic ore deposition controlled by sulphate reducing bacteria the metals probably having originated from regionally mineralized triassic or liassic formations rock eval pyrolysis data complemented by biomarkers show that the organic matter reached only the organic diagenesis catagenesis transition owing to burial pb deposit as in many pb zn s deposits the hydrocarbons almost certainly autochthonous show no indication of relatively late alteration by biodegradation or water washing the presence of hopanes c 27 35 with high abundance in the c 27 32 range indicate that intense bacterial activity occurred during early diagenesis under su ic anoxic conditions this interpretation is reinforced by the presence of n alkanes in the range n c 22 to n c 28 dominated by compounds with an even number of carbon atoms which may have derived from the reduction of bacterial fatty acids except for these even number n alkanes the organic geochemical evidence for sulphate reducing bacteria during early diagenesis must remain equivocal

ocean response to low frequency wind forcing with application to the seasonal variation in the florida straits gulf stream transport abstract the linear response of a two layer ocean model to a periodic wind stress curl in the presence of bottom photography has been invesrigated for periods much less than the time taken for the wind generated baroclinic rossby waves to pass over the topography i e short periods the ocean response is primarily that for a homogenous ocean and thus strongly modified by topography for periods much longer than this time i e long periods the rossby waves compensate for the effect of topography and the non topographic sverdrup balance holds at intermediate periods the phase and amplitude of the transport variations over topography can be understood in terms of a non equilibrium baroclinic response forcing the barotropic mode over topography with relatively little feedback from the barotropic mode a the bottom topography therefore imposes a low pass filter on the transport variations for the atlantic at 25 n the long period limit is of the order of years to decades depending on the location of the wind stress variability so at annual period the non topographic sverdrup balance is not applicable variations in transport can be forced by a wind stress over varying topography and by the passage of a coastal baroclinic kelvin wave over topography at short periods including the annual the effect of strong bottom topography is similar to that of an island it was found that both with and without associated bottom topography a north south island acts as a spatial filter such that wind stress forcing of larger north south scale to the east of the island contributes proportionately more to transport variations to the west of the island than forcing of smaller north south scale

causes of large scale sea level variations in the southern ocean analyses of sea level and a barotropic model 1 we analyze a decade of sea surface height ssh measurements in the southern ocean from the topex poseidon and ers altimeters with a focus on the variability at timescales 2 years among the different processes contributing to large scale ssh variations the barotropic response to the winds dominates poleward of 50 s while thermosteric processes dominate equatorward except for resonant basins for the barotropic modes and regions of intense eddy activity a finite element barotropic model has been developed to analyze the vorticity budget the ssh from the model agrees well with observations the leading barotropic mode which is annular and is confined near antarctica is responsible for most of the barotropic circumpolar transport it is coherent with the zonally integrated eastward wind stress consistent with a free mode response although previously evidenced in bottom pressure data this mode is only partially seen in altimeter data because of ice coverage it nevertheless distinctly appears above the pacific ridges where it expands meridionally up to midlatitudes in the rest of the domain several regions coherent with the local wind stress curl are found these are regions isolated by f h contours mostly deep basins an analysis of the vorticity budget shows that generally topographic sverdrup balance is the leading process for periods 50 days but in some regions resonant basins diffusive and nonstationary terms are important a model experiment shows that transients redistribute energy along f h waveguides contributing to drain resonant regions as was hypothesized in previous works

evidence for wind driven current fluctuations in the western north atlantic two subsurface current meter moorings were deployed for 20 months along 70 w in a low energy portion of the western north atlantic the resulting data were compared with estimates of the wind stress curl in an attempt to seek a relationship between currents below the mixed layer and meteorological forcing at subinertial frequencies currents and temperature tend to be significantly coherent with the curl and are most coherent with the curl at remote locations usually more than 500 km away from the mooring and generally to the east coherences generally decrease with increasing frequency the current response is surface intensified a linear stratified model for stochastically wind forced rossby waves in a flat bottomed ocean is presented as an attempt to rationalize the results the effort was not entirely successful so that it appears that a more realistic model perhaps including bottom topography and mean currents will be needed to rationalize these observations fully

a perspective on the future of physical oceanography the ocean flows because it is forced by winds tides and exchanges of heat and freshwater with the overlying atmosphere and cryosphere to achieve a state where the defining properties of the ocean such as its energy and momentum do not continuously increase some form of dissipation or damping is required to balance the forcing the ocean circulation is thought to be forced primarily at the large scales characteristic of ocean basins yet to be damped at much smaller scales down to those of centimetre sized turbulence for decades physical oceanographers have sought to comprehend the fundamentals of this fractal puzzle how the ocean circulation is driven how it is damped and how ocean dynamics connects the very different scales of forcing and dissipation while in the last two decades significant advances have taken place on all these three fronts the thrust of progress has been in understanding the driving mechanisms of ocean circulation and the ocean s ensuing dynamical response with issues surrounding dissipation receiving comparatively little attention this choice of research priorities stems not only from logistical and technological difficulties in observing and modelling the physical processes responsible for damping the circulation but also from the untested assumption that the evolution of the ocean s state over time scales of concern to humankind is largely independent of dissipative processes in this article i illustrate some of the key advances in our understanding of ocean circulation that have been achieved in the last 20 years and based on a range of evidence contend that the field will soon reach a stage in which uncertainties surrounding the arrest of ocean circulation will pose the main challenge to further progress it is argued that the role of the circulation in the coupled climate system will stand as a further focal point of major advances in understanding within the next two decades supported by the drive of physical oceanography towards a more operational enterprise by contextual factors the basic elements that a strategy for the future must have to foster progress in these two areas are discussed with an overarching emphasis on the promotion of curiosity driven fundamental research against opposing external pressures and on the importance of upholding fundamental research as the apex of education in the field

monocyclic alkanes in ordovician organic matter abstract the major compounds in the c 15 branched cyclic alkane fractions of two ordovician oils pine unit and midland farms oils and an immature ordovician rock guttenberg oil rock are monocyclics one series of these compounds was identified as n alkylcyclohexanes and another tentatively identified as methyl n alkylcyclohexanes the carbon number distribution of these compounds resembled those of the n alkanes found in these samples with an odd carbon number predominance it is suggested that the monocyclic alkanes in these ordovician samples may be principally derived from the cyclisation of straight chain algal fatty acids by mechanisms that involve decarboxylation however there is evidence from the m z 97 fragmentograms of these samples to indicate that methyl n alkylcyclohexanes can also be derived from fatty acids by a less preferred mechanism that does not involve decarboxylation or from other precursors in addition a sample of kerogen from the guttenberg oil rock was hydrously pyrolysed the saturated hydrocarbon products of this experiment showed very similar distributions including monocyclics to those observed in the ordovician oils this suggests that although the oils and the guttenberg oil rock come from widely differing geographical locations their precursor algal derived organic matter was very similar