interpretations of observed climatological patterns in stratospheric gravity wave variance observational analyses of gravity waves in the stratosphere have revealed various climatological patterns in gravity wave activity seasonal geographical and vertical variations have all been observed in this work a linear model of gravity wave propagation is applied to investigate the underlying causes of some of the observed patterns a collection of monochromatic gravity waves that represent a broad spectrum of wavenumbers and frequencies is input at 6 km altitude in the model propagation of the waves through realistic background atmospheric wind and stability fields is treated with linear ray theory and a simple saturation condition to limit amplitudes to stable values the wave spectrum at the 6 km source height is specified to be constant at all latitudes longitudes and times so the variability that appears at higher altitudes is due entirely to background atmosphere variations before the model results are compared to the observations the spectrum of waves is filtered in a way that mimics the limitations of each of the observation techniques the filtering is described in terms of vertical wavelength and is referred to as the observational filter in a vertically varying background wind gravity waves are doppler shifted in intrinsic frequency and refracted to different vertical wavelengths as they propagate vertically through the atmosphere the observational filter and the wave refraction effects can thus couple in interesting ways that have not been explicitly considered in previous work the model shows that this coupling can give rise to geographical seasonal and vertical variations in gravity wave observations without any variations in the spectrum or amplitude of gravity wave sources in the troposphere thus careful consideration of both the background wind profile and observational filter can greatly affect the interpretation of the observed climatological patterns in gravity wave activity

applications of organic geochemistry to paleolimnological reconstructions a summary of examples from the laurentian great lakes the organic matter content of lake sediments contains information that helps to reconstruct past environmental conditions evaluate histories of climate change and assess impacts of humans on local ecosystems the elemental isotopic and molecular compositions of organic matter buried in sediment provide evidence of the biota that have lived in a lake and its catchment area and they serve as proxies of organic matter delivery and accumulation sedimentary records from the north american great lakes provide examples of applications of organic geochemistry to paleolimnological reconstructions the records of these lakes date from retreat of the laurentide ice sheet around 12 ka include the mid holocene hypsithermal and show consequences of recent human changes low corg ntotal ratios indicate that most of the sediment organic matter in the great lakes is from algal production yet changes in biomarker molecule compositions also show that varying amounts of land plant organic matter have been delivered to the lakes elevated algal productivity that accompanies nutrient enrichments of lake waters is recorded as excursions to less negative 13c values in the organic matter of sediments that were deposited in the 1960s and 1970s increased organic carbon mass accumulation rates mirror the isotopic excursions in most parts of the great lakes accumulations of petroleum residues and pyrogenic polycyclic aromatic hydrocarbons in sediments identify fluvial and eolian delivery of organic matter components to different parts of the great lakes emerging applications of multiple and novel organic geochemical proxies to paleolimnological reconstructions are promising yet some potentially important measurements remain underutilized

gravity wave and orographic wave activity observed around the antarctic and arctic stratospheric vortices by the cosmic gps ro satellite constellation 1 polar stratospheric gravity wave activity is studied using data from the constellation observing system for meteorology ionosphere and climate cosmic global positioning system radio occultation gps ro waves with vertical wavelengths of 2 to 15 km are considered the temperature variance 2 is used as a measure of wave activity and is studied on isentropic surfaces large intermittent orographic wave activity is identified during austral spring 2007 above the patagonian andes and the antarctic peninsula where 2 in the stratosphere increases by up to a factor of 5 for periods of 5 days to a few weeks the 2 are also investigated in equivalent latitudes to allow a direct comparison with the changing vortex structure the october 2007 2 inside the antarctic vortex boundary region at 400 600 k is one and a half times that outside the vortex this region of enhanced 2 descends in time and is not observed during the decay of the arctic vortex during the boreal winter of 2006 2007 orographic wave activity is observed above scandinavia and greenland an analysis of the 400 k and the 450 k levels in both hemispheres shows a strong relationship between enhanced 2 and the location of the vortex edge suggesting that the waves observed are propagating poleward and are guided to higher altitudes by the vortex the line of sight of the occultations shows a preference for north south alignment indicating that cosmic favors the detection of orographic waves above the north south oriented mountain ranges considered here

low temperature hydrothermal maturation of organic matter in sediments from the atlantis ii deep red sea abstract hydrocarbons and bulk organic matter of two sediment cores no 84 and 126 chain 61 cruise located within the atlantis ii deep have been analyzed although the brines overlying the coring areas were reported to be sterile microbial inputs and minor terrestrial sources represent the major sedimentary organic material this input is derived from the upper water column above the brines both steroid and triterpenoid hydrocarbons show that extensive acid catalyzed reactions are occurring in the sediments in comparison with other hydrothermal guaymas basin or intrusive systems cape verde rise the atlantis ii deep exhibits a lower degree of thermal maturation this is easily deduced from the elemental composition of the kerogens and the absence of polynuclear aromatic hydrocarbons of a pyrolytic origin in the bitumen the lack of carbon number preference among the n alkanes suggests especially in the case of the long chain homologs that the organic matter of atlantis ii deep sediments has undergone some degree of catagenesis however the yields of hydrocarbons are much lower than those observed in other hydrothermal areas the effect of lower temperature and poor source rock characteristics appear to be responsible for the differences

highly isotopically depleted isoprenoids molecular markers for ancient methane venting abstract we propose that organic compounds found in a miocene limestone from marmorito northern italy are source markers for organic matter present in ancient methane vent systems cold seeps the limestone contains high concentrations of the tail to tail linked acyclic c20 isoprenoid 2 6 11 15 tetramethylhexadecane crocetane a c25 homolog 2 6 10 15 19 pentamethylicosane pme and a distinctive glycerol ether lipid containing 3 7 11 15 tetramethylhexadecyl phytanyl moieties the chemical structures of these biomarkers indicate a common origin from archaea their extremely 13c depleted isotope compositions 13c 108 to 115 6 pdb suggest that the respective archaea have directly or indirectly introduced isotopically depleted methane derived carbon into their biomass we postulate that a second major cluster of biomarkers showing heavier isotope values 13c 88 is derived from sulfate reducing bacteria srb the observed biomarkers sustain the idea that methanogenic bacteria in a syntrophic community with srb are responsible for the anaerobic oxidation of methane in marine sediments marmorito may thus represent a conceivable ancient scenario for methane consumption performed by a defined two membered bacterial consortium 1 archaea that perform reversed methanogenesis by oxidizing methane and producing co2 and h2 and 2 srb that consume the resulting h2 furthermore the respective organic molecules are unlike other compounds tightly bound to the crystalline carbonate phase the marmorito carbonates can thus be regarded as cold seep microbialites rather than mere authigenic carbonates

archaea mediate anaerobic oxidation of methane in deep euxinic waters of the black sea we evaluate anaerobic oxidation of methane aom in the black sea water column by determining distributions of archaea specific glyceryl dialkyl glyceryl tetraethers gdgts and 13c isotopic compositions of their constituent biphytanes in suspended particulate matter spm sinking particulate matter collected in sediment traps and surface sediments we also determined isotopic compositions of fatty acids specific to sulfate reducing bacteria to test for biomarker and isotopic evidence of a syntrophic relationship between archaea and sulfate reducing bacteria in carrying out aom bicyclic and tricyclic gdgts and their constituent 13c depleted monocyclic and bicyclic biphytanes down to 67 indicative of archaea involved in aom were present in spm in the anoxic zone below 700 m depth in contrast gdgt 0 and crenarchaeol derived from planktonic crenarchaeota dominated the gdgt distributions in the oxic surface and shallow anoxic waters fatty acids indicative of sulfate reducing bacteria i e iso and anteiso c15 were not strongly isotopically depleted e g 32 to 25 although anteiso c15 was 5 more depleted in 13c than iso c15 our results suggest that either aom is carried out by archaea independent of sulfate reducing bacteria or those sulfate reducing bacteria involved in a syntrophy with methane oxidizing archaea constitute a small enough fraction of the total sulfate reducing bacterial community that an isotope depletion in their fatty acids is not readily detected sinking particulate material collected in sediment traps and the underlying sediments in the anoxic zone contained the biomarker and isotope signature of upper water column archaea aom specific gdgts and 13c depleted biphytanes characteristic of the spm in the deep anoxic zone are not incorporated into sinking particles and are not efficiently transported to the sediments this observation suggests that sediments may not always record aom in overlying euxinic water columns and helps explain the absence of aom derived biomarkers in sediments deposited during past periods of elevated levels of methane in the ocean

a newly discovered norisoprenoid 2 6 15 19 tetramethylicosane in cretaceous black shales a novel c24 acyclic isoprenoid 2 6 15 19 tetramethylicosane tme has been unambiguously identified using a synthesised standard in the saturated hydrocarbon fractions and in the kerogen pyrolysates of samples from a lower albian black shale from southeastern france in addition a novel c26 acyclic isoprenoid 10 ethyl 2 6 15 19 tetramethylicosane etme was tentatively identified these compounds appear to be structurally strongly related to the relatively well known c25 isoprenoid 2 6 10 15 19 pentamethylicosane pme and their co occurrence in these sediments and similar 13c contents indicates a common origin this suggests an alternative biosynthetic pathway for the biosynthesis of pme via the methylation of tme rather than the tail to tail coupling of farnesyl and geranyl these irregular isoprenoids are likely to have originated as parts of ether lipids in some unknown archaea but exactly which organisms biosynthesised these compounds remains uncertain

a statistical study of gravity waves in the polar regions based on operational radiosonde data gravity waves in the lower polar stratosphere are examined using operational radiosonde observations gathered from 33 stations over a period of 10 years both the potential and kinetic energies of the gravity waves vary annually and reach maxima in winter in the arctic and in spring in the antarctic in the antarctic spring a region of large gravity wave energy propagates downward following the movement of a zone of high static stability associated with southern hemispheric warming moreover the enhanced energy region and the high stability zone coincide in the horizontal plane and move gradually from 135 e 50 s to 45 w 70 s over the south pole the vertical and horizontal directions of wave propagation are examined using hodograph analysis in the vertical most gravity waves transfer energy upward in the arctic while the percentage of downward energy propagation is relatively high in winter and spring in the antarctic horizontally gravity waves propagate westward relative to the mean wind in the arctic while in the antarctic the dominant direction varies from station to station the correlation between gravity wave energy in the lower stratosphere and the mean wind is also examined in the arctic gravity wave energy is highly correlated with the surface wind though in the antarctic it correlates with the stratospheric wind these results suggest that gravity waves observed in the arctic are forced by topography whereas in antarctica some sources may exist in the stratosphere one such source candidate is likely to be the polar night jet

organofacies and paleoenvironment of lower carboniferous mudstones dishuiquan formation in eastern junggar nw china abstract the sedimentary rocks of the dishuiquan formation represent an important potential source for volcanic rock reservoirs and record the transition of the depositional environment from marine to terrestrial during paleo junggar oceanic subduction the source rock potential and paleoenvironment of mudstones from dishuiquan formation in eastern junggar were determined by organic petrography rock eval molecular and stable carbon 13 c analyses toc s 2 and hydrogen index hi values suggest a fair to good organic richness in mudstone samples from the c 2 well moreover an early mature to mature state for all the samples is inferred based on the rock eval and biomarker parameters the maceral composition molecular geochemistry and carbon isotopic results for kerogen reveal that all the mudstone samples are characterized by a mixed organic matter assemblage types ii iii with relatively high percentages of terrigenous organic matter the low to intermediate values of pr ph and the high abundances of carotene and gammacerane indicate the presence of a dysoxic reducing high salinity sedimentary environment during the deposition of the dishuiquan formation numerous parameters derived from the organic geochemical analyses indicate that the terrigenous organic matter increased with decreasing salinity and oxidation in the sedimentary environment this study concludes that a warm wet climate provided a continuous fluvial input of terrigenous plant debris and fresh water the organic geochemical data combined with the tectonic setting reveal a restricted semi closed marine depositional environment during the deposition of the dishuiquan formation in the early carboniferous

bacterial and algal hydrocarbons in sediments from a saline antarctic lake ace lake capillary gas chromatography mass spectrometry c gc ms and iatroscan thin layer chromatography flame ionisation detection tlc fid were used to study hydrocarbon distributions in a sediment core from ace lake a saline meromictic lake in the vestfold hills of antarctica hydrocarbons were abundant in most core sections up to 125 g g dry wt particularly in near surface samples and the distributions were very complex major constituents were identified as phytane 2 6 10 15 19 pentamethyleicosane tetrahydrosqualene a mixture of phytenes cholesta 3 5 diene and fern 7 ene smaller amounts of sterenes and hopenes were also present the predominance of the first 3 acyclic isoprenoids in sediments buried less than 30 cm is consistent with high populations of methanogenic bacteria known to be present phytenes were abundant in all core sections and there was no relationship between their abundance and that of phytane which suggests that they were not derived from methanogenic bacteria phytadienes were minor constituents at all depths studied an unusual feature of some distributions was the high concentrations of fern 7 ene which was the major hydrocarbon in the 20 25 cm core section this alkene was only abundant in sediments which contained high concentrations of methanogen markers suggesting that it may also be indicative of anoxic depositional environments a possible source might be from purple non sulphur bacteria high concentrations of straight chain c29 and c34 alkenes were also found in these sediments but their origin has not been determined major changes in the hydrocarbon distributions with depth indicate that the depositional environment in the lake has altered dramatically since the lake was formed less than 8000 years ago the present condition of permanent anoxic bottom waters probably developed only in the last 1000 years

global comparisons of organic matter in sediments across the cretaceous tertiary boundary a tract the cretaceous tertiary k t boundary is marked by extensive changes in the sedimentary fossil record of continental and marine life organic matter in sediments from above and below the k t boundary has been studied to identify consequences of the biotic extinctions and of the changes in biological productivity which occurred at this time data from locations encompassing a variety of marine paleoenvironments were examined to assess the global extent and local expressions of these biological changes characterizations of organic matter included rock eval pyrolysis stable carbon isotope ratios and distributions of extractable biomarkers in general organic carbon concentrations are a few tenths of a percent in the chalks and marls above and below the k t boundary in some boundary clay samples concentrations up to 5 are found the elevated amounts near the boundary result from oxidation of marine organic matter consequent dissolution of carbonates and concentration of the surviving organic matter at all locations the organic matter has been microbially reworked and evidently was deposited in oxidizing environments carbon isotope shifts in open marine sediments suggest biological productivity was depressed following the k t boundary repetition of these changes at different locations verifies the global extent of the boundary event yet local variations in its expression are evident

a gravity wave climatology for antarctica compiled from challenging minisatellite payload global positioning system champ gps radio occultations 1 the seasonal geographical and altitudinal dependence of gravity wave activity in the lower stratosphere over antarctica is presented gravity wave activity is estimated by calculating potential energy ep from radio occultation profiles obtained by the challenging minisatellite payload global positioning system champ gps experiment significant seasonal variation of wave activity is observed smaller wave activity in summer is attributed to waves with small phase velocities experiencing critical level filtering at other times of the year when wave activity is large less filtering occurs and the strong background wind is likely to cause doppler shifting of waves to longer vertical wavelengths which can reach larger amplitudes before saturating relationships between gravity wave activity and geographic location indicate that topography is a strong source for wave activity especially over the antarctic peninsula however wind rotation in this area was found to reduce the wave energy in summer at certain altitudes a strong enhancement of wave energy is observed at the edge of the polar vortex again reduced critical level filtering and doppler shifting in the area of the jet are likely to be major causes for this finding possible limitations to this study due to observational filtering are discussed

authigenic carbonate formation revealed by lipid biomarker inventory at hydrocarbon seeps a case study from the okinawa trough abstract authigenic carbonates were recovered from the northern okinawa trough at 540 700 m water depth development of microbial communities and seepage dynamics driving the precipitation of authigenic carbonates remains poorly constrained even though the source of methane rich fluids formation of fe rich carbonates and the potential driving forces were previously reported here petrologic observations stable carbon and oxygen isotopic compositions mineralogy and lipid inventories of authigenic carbonates from the northern okinawa trough were analyzed the carbonate minerals were comprised predominantly of aragonite high magnesium calcite and siderite the presence of molecular fossils diagnostic for anaerobic methane oxidizing archaea anme and sulfate reducing bacteria srb with pronounced 13c depletions as low as 134 together with highly negative 13ccarb values as low as 55 8 suggest that the carbonates precipitated from anaerobic oxidation of methane aom with microbial methane as the predominant carbon source the difference between measured and calculated 18ocarb values based on 0 of sea water 18o vs v smow was higher than 3 in one of the carbonates ggd16 reflecting an origin from gas hydrate dissociation most of the carbonates revealed 18o offsets between measured and calculated values within 3 or a lower measured 18o than calculated value suggesting a mixture of methane derived carbonates low 13c high 18o and detrital origin carbonates high 13c low 18o biomarker patterns varied significantly among samples a suite of 13c depleted biomarkers indicated the predominance of an anme 1 assemblage for all samples suggesting carbonates formed at low to medium methane flux the predominance of anme 1 abundant detrital minerals and allochthonous biomarkers as well as low carbonate contents indicate that most samples formed at greater depth within the sediment column only one carbonate sample in this study is interpreted to have precipitated at relatively shallower depth as indicated by the occurrence of crocetane dominance of aragonite and higher overall carbonate content

impact of dia and catagenesis on sulphur and oxygen sequestration of biomarkers as revealed by artificial maturation of an immature sedimentary rock hydrous pyrolysis of an immature ro 0 25 sulphur rich marl from the gessoso solfifera formation messinian in the vena del gesso basin was carried out at 160 c t 330 c for 72 h to study the effect of progressive diagenesis and early catagenesis on the abundance and distribution of sulphur containing and sulphur and oxygen linked carbon skeletons in low molecular weight and high molecular weight fractions e g kerogen to this end compounds in the saturated hydrocarbon fraction monoaromatic hydrocarbon fraction polyaromatic hydrocarbon fraction alkylsulphide fraction and ketone fraction were quantified as well as compounds released after desulphurisation of the polar fraction and hilialh4 treatment of the desulphurised polar fraction sulphur bound phytane and 20r 5 14 17 h and 20r 5 14 17 h c27 c29 steranes in the polar fraction become less abundant with increasing maturation temperature whereas the amount of their corresponding hydrocarbons increases in the saturated hydrocarbon fraction carbon skeletons that are bound in the kerogen by multiple bonds e g c38n alkane and isorenieratane are first released into the polar fraction and then as free hydrocarbons these changes occur at relatively low levels of thermal maturity ro 0 6 as evidenced by the immature values of biomarker maturity parameters such as the c35 hopane ratio and the 22s 22s 22r 17 21 h c35 hopane ratio sulphur and oxygen bound moieties present in the polar fraction are not stable with increasing thermal maturation however alkylthiophenes ketones 1 2 di n alkylbenzenes and free n alkanes seem to be stable thermal degradation products of these sulphur and oxygen bound moieties thus apart from free n alkanes which are abundantly present in more mature sedimentary rocks and crude oils alkylthiophenes 1 2 di n alkylbenzenes and ketones can also be expected to occur the positions of the thiophene moiety and the carbonyl group coincide with the original positions of the functional groups of their precursors thus important information about palaeobiochemicals is retained throughout the sequestration degradation process

geochemical and biological marker assessment of depositional environments using brazilian offshore oils abstract a combined geochemical and molecular characterization of a wide selection of oils from the major brazilian offshore basins has been undertaken the elemental sulphur nickel and vanadium and bulk oapi and 13c properties of each sample been considered together with its molecular composition determined using liquid and gas chromatography and quantitative biological marker investigations using gas chromatography mass spectrometry for alkanes the results reveal significant differences in the chemical features of the various oils which enable them to be divided into five groups the distinction of the groups appears to reflect differences in the depositional environment of the source rocks of the oils each group is correlated tentatively with source rocks laid down in a specific depositional regime namely lacustrine freshwater lacustrine saline water marine evaporitic marine carbonate or marine deltaic the diagnostic features that allow this classification are the relative abundance and carbon number distributions of n alkanes pristane phytane ratios sulphur nickel and vanadium contents carbon isotope data the absolute concentrations of hopanes and steranes and their abundance relative to 4 methylsteranes and also the occurrence and abundance of several specific biological markers including 18 h oleanane gammacerane carotane tricyclic terpanes higher acyclic isoprenoids 28 30 bisnorhopane and 25 28 30 trisnorhopane this investigation shows the value of a combined geochemical and molecular approach in the assessment of the palaeoenvironment of deposition of the source rocks which gave rise to the oils

sources and deposition of organic matter in cretaceous passive margin deep sea sediments a synthesis of organic geochemical studies from deep sea drilling project site 603 outer hatteras rise abstract the results of organic geochemical studies of rock samples from cretaceous strata at site 603 on the outer hatteras rise are reviewed and integrated with their lithostratigraphic information although most of the strata contain little organic carbon black shales enriched in organic matter were found in two settings these rocks exist as claystones in the aptian to turonian hatteras formation and as marlstones in the neocomian blake bahama formation terrigenous organic matter predominates in these deposits except in cenomanian and valanginian rocks where marine material becomes dominant organic carbon concentrations in cenomanian black claystones are higher than any previously reported from the western north atlantic but lower than the concentrations found in the eastern north atlantic black shales at site 603 appear to result from downslope transport and rapid reburial of coastal and ocean margin sediments by turbidity flows deep basin anoxia is not a major factor except during the cenomanian turonian when the entire atlantic ocean may have briefly become anoxic organic matter in the sediments from all locations is thermally immature

lidar observations of stratospheric gravity waves from 2011 to 2015 at mcmurdo 77 84 s 166 69 e antarctica 1 vertical wavelengths periods and frequency and vertical wave number spectra five years of atmospheric temperature data collected with an fe boltzmann lidar by the university of colorado group from 2011 to 2015 at arrival heights are used to characterize the vertical wavelengths periods vertical phase speeds frequency spectra and vertical wave number spectra of stratospheric gravity waves from 30 to 50 km altitudes over 1000 dominant gravity wave events are identified from the data the seasonal spectral distributions of vertical wavelengths periods and vertical phase speeds in summer winter and spring fall are found obeying a lognormal distribution both the downward and upward phase progression gravity waves are observed by the lidar and the fractions of gravity waves with downward phase progression increase from summer 59 to winter 70

inertia gravity waves in antarctica a case study using simultaneous lidar and radar measurements at mcmurdo scott base 77 8 s 166 7 e 1 this study presents the first coincident observation of inertia gravity waves igws by lidar and radar in the antarctic mesopause region this is also the first known observation of two simultaneous igws at the same location an fe boltzmann lidar at arrival heights 77 8 s 166 7 e provides high resolution temperature data and a co located mf radar provides wind data on 29 june 2011 coherent wave structures are observed in both the fe lidar temperature and mf radar winds two dominant waves are determined from the temperature data with apparent periods of 7 7 0 2 and 5 0 0 1 h and vertical wavelengths of 22 2 and 23 2 km respectively the simultaneous measurements of temperature and wind allow the intrinsic wave properties to be derived from hodograph analyses unambiguously the analysis shows that the longer period wave propagates northward with an azimuth of 11 5 clockwise from north this wave has a horizontal wavelength of h 2 2 0 2 103 km and an intrinsic period of i 7 9 0 3 h the intrinsic horizontal phase speed cih for this wave is 80 4 m s while the horizontal and vertical group velocities cgh and cgz are 48 3 m s and 0 5 0 1 m s respectively the shorter period wave has i 4 5 0 3 h and 100 4 with h 1 1 0 1 103 km and cih 68 5 m s its group velocities are cgh 58 5 m s and cgz 1 1 0 1 m s therefore both waves propagate with very shallow elevation angles from the horizon 0 6 0 1 and 1 1 0 1 for the longer and shorter period waves respectively but originate from different sources our analysis suggests that the longer period igw most likely originates from the stratosphere in a region of unbalanced flow

an organic geochemical profile of the toarcian anoxic event in northern italy abstract a suite of black shales calcareous shales and limestones representing the toarcian anoxic event jurassic 192 ma was collected from a 14 m length of core taken from the belluno trough northern italy and examined in detail to assess variations in depositional environment during this interval geochemical and optical data indicate organic matter of algal and bacterial origin with only trace contribution from terrestrial sources detailed biological marker data interpreted with the aid of multivariate statistics demonstrate fluctuations in primary producers and bacterial populations during black shale deposition the onset of the anoxic event was not abrupt but characterized by an apparent gradual development of anoxia and consequent enhanced organic matter preservation different hopane biomarkers proved especially useful in recognizing preservation potential in the section and correlate well with other preservation indicators increased oxygenation at the end of the event may have been associated with changes in primary productivity

stereochemical studies of acyclic isoprenoids xii lipids of methanogenic bacteria and possible contributions to sediments abstract abundant volatile lipids of methanobacterium thermoautotrophicum and methanosarcina barkeri include isoprenoid hydrocarbons c30 and c15 c20 and c25 isoprenoid alcohols m barkeri contains 2 6 10 15 19 pentamethyleicosane whose relative stereochemistry is the same as found in marine sediments indicating that it is a marker of methanogenic activity the c20 c30 and c25 alkenes in m thermoautotrophicum also have a preferred sterochemistry the latter have the 2 6 10 14 18 pentamethyleicosanyl skeleton suggesting that the alkane in marine sediments may derive from methanogens the stereochemistry of squalane in a marine sediment is also compatible with an origin in methanogens in contrast the stereochemistry of pristane in m thermoautotrophicum indicates a fossil fuel contaminant origin suggesting that this and certain other alkanes reported in archaebacteria might also be of contaminant origin there is therefore little evidence at present that the pristane in immature marine sediments originates in methanogens the c15 and c20 saturated alcohols in m thermoautotrophicum have mainly the all r configuration if this is generally true for methanogens the c20 alcohol in the messel shale may originate mainly from methanogens whereas that in the green river shale may originate mainly from photosynthetic organisms

polar mesosphere and lower thermosphere dynamics 1 mean wind and gravity wave climatologies 1 mean wind and gravity wave climatologies are presented for the polar mesosphere and lower thermosphere mlt the data were derived using mf radars at davis 69 s 78 e and syowa 69 s 40 e in the antarctic and poker flat 65 n 147 w and andenes 69 n 16 e in the arctic the dynamics of the antarctic mlt are found to be significantly different from the arctic mlt summer maxima in both the westward and equatorward winds occur closer to the solstice in the antarctic than in the arctic the greater symmetry around the solstice suggests radiative effects may play a greater role in controlling the state of the antarctic mlt than in the arctic where dynamical effects appear to be more important gravity wave observations also suggest that wave drag may be greater in the arctic than in the antarctic the equatorward flow near the mesopause persists later in summer in the arctic than in the antarctic as do observations of polar mesospheric clouds and polar mesospheric summer echoes all three phenomena begin at about the same time in each hemisphere but end later in the arctic than in the antarctic it is proposed that the magnitude of the meridional winds can be used as a proxy for gravity wave driving and the consequent adiabatic cooling in the mlt seasonal variations in gravity wave activity are predominately combinations of annual and semiannual components significant hemispheric differences are observed for both the timing and magnitude of these seasonal variations

carbon isotopic compositions of prokaryotic lipids as tracers of carbon cycling in diverse settings recent work has highlighted the ubiquity of bacteria and archaea and continues to affirm their significance in diverse biogeochemical processes the 13c values and distributions of diagnostic lipids derived from such microorganisms can provide insights into prokaryotic processes in modern settings and are one of the few means by which past prokaryotic processes in depositional settings can be elucidated here we present a brief review of prokaryotic lipids commonly observed in sediments and the controls on their carbon isotopic compositions we then present two case studies one of mediterranean cold seeps at which anaerobic oxidation of methane occurs and one of a holocene peat deposit in which a variety of aerobic and anaerobic microorganisms govern the degradation of organic matter these two studies illustrate the potential utility of compound specific carbon isotope analyses to deconvolute pathways of carbon flow in microbial communities

gc ms detection and significance of crocetane and pentamethylicosane in sediments and crude oils abstract the occurrence of the archaeal biomarkers crocetane and pentamethylicosane pmi in sediments and crude oils was investigated using gc ms and gc ms ms selected ion monitoring sim and multiple reaction monitoring mrm protocols designed to detect the c 20 and c 25 irregular isoprenoids were evaluated a method for the preferential detection of crocetane over phytane its more abundant isomer was refined using authentic compounds crocetane was found to be present in modern sediments from both aerobic and anaerobic water columns and in sediment from the 1640 ma barney creek formation providing evidence for the antiquity of its biosynthesis crocetane was also detected in several perth basin crude oils and in the kockatea shale their putative source rock and in canning basin oils although mrm analysis could only verify its occurrence in canning oils of devonian age equivocal data from ordovician and carboniferous canning basin oils highlight the need for extreme caution when attempting to distinguish between acyclic isoprenoid isomers pmi was identified by mrm in a miocene monterey sediment and in a modern antarctica sediment on the other hand the c 25 isoprenoid hydrocarbon peak detected in triassic and older sediments was consistently identified as the regular isomer i 25 reg whenever it was sufficiently abundant for mrm to be applied

energy enhancements of gravity waves in the antarctic lower stratosphere associated with variations in the polar vortex and tropospheric disturbances 1 gravity waves in the antarctic lower stratosphere are examined using original operational radiosonde data obtained at syowa station 69 0 s 39 6 e with fine vertical resolution in the lower stratosphere the temporal variation in gravity wave energy depends on height in the height region of 13 15 km just above the tropopause the seasonal variation in gravity wave energy is not evident the wave energy is rather enhanced when the absolute value of potential vorticity in the upper troposphere becomes small over syowa station this fact implies that tropospheric disturbances affect the dynamical processes of gravity waves there however the gravity wave energy in the height region of 15 25 km shows clear seasonal variation having a maximum in spring the time variation in gravity wave energy is examined in detail in terms of the polar vortex by using the equivalent latitude coordinate energy enhancements occur when the edge of the polar vortex approaches syowa station and the enhancements are especially large when the polar vortex breaks down in spring these results suggest that height variation in the background atmosphere leads to the difference of wave characteristics between the two height regions the enhancements of wave energy are partly explained as modification of the wave structure by the background wind speed and the static stability but it is also likely that enhancements of wave activity contribute to the energy enhancement at the edge of the polar vortex in spring

a study of multiple tropopause structures caused by inertia gravity waves in the antarctic abstractmultiple tropopauses mts defined by the world meteorological organization are frequently detected from autumn to spring at syowa station 69 0 s 39 6 e the dynamical mechanism of mt events was examined by observations of the first mesosphere stratosphere troposphere mst radar in the antarctic the program of the antarctic syowa mst incoherent scatter is radar pansy and of radiosondes on 8 11 april 2013 the mt structure above the first tropopause is composed of strong temperature fluctuations by a detailed analysis of observed three dimensional wind and temperature fluctuation components it is shown that the phase and amplitude relations between these components are consistent with the theoretical characteristics of linear inertia gravity waves igws numerical simulations were performed by using a nonhydrostatic model the simulated mt structures and igw parameters agree well with the observation in the analysis using the numerical simulation data it is seen that igws were generate

the role of minerals in the thermal alteration of organic matter iv generation of n alkanes acyclic isoprenoids and alkenes in laboratory experiments a series of pyrolysis experiments utilizing two different immature oil prone kerogens type i green river formation kerogen type ii monterey formation kerogen mixed with common sedimentary minerals calcite illite or na montmorillonite was conducted to study the effects of minerals on the generation of n alkanes acyclic isoprenoids and alkenes during laboratory simulated catagenesis of kerogen the influence of clay minerals on the aliphatic hydrocarbons is critically dependent on the water concentration during laboratory thermal maturation under extremely low contents of water i e dry pyrolysis where only pyrolysate water is present c12 range n alkanes and acyclic isoprenoids are mostly destroyed by montmorillonite but undergo only minor alteration with illite both clay minerals significantly reduce alkene formation during dry pyrolysis under hydrous conditions mineralwater 2 1 the effects of the clay minerals are substantially reduced in addition the dry pyrolysis experiments show that illite and montmorillonite preferentially retain large amounts of the polar constituents of bitumen but not n alkanes or acyclic isoprenoids therefore bitumen fractionation according to polarity differences occurs in the presence of these clay minerals by this process n alkanes and acyclic isoprenoids are concentrated in the bitumen fraction that is not strongly adsorbed on the clay matrices the extent of these concentration effects is greatly diminished during hydrous pyrolysis in contrast calcite has no significant influence on the thermal evolution of the hydrocarbons in addition calcite is incapable of retaining bitumen therefore the fractionation of n alkanes or acyclic isoprenoids relative to the polar constituents of bitumen is insignificant in the presence of calcite

biogeochemical formation of calyx shaped carbonate crystal fans in the subsurface of the early triassic seafloor abstract the kuh e dena sedimentary section in iran developed on the southwestern margin of the neotethys ocean the fossil and bioturbation lean early triassic section late dienerian to early smithian is typified by finely laminated calcareous shales that are interbedded with laterally extending carbonate beds which are mostly composed of calyx shaped carbonate crystal fans the calyxes consist of fibrous crystals that apparently formed within the subseafloor in soft water saturated sediment by displacive growth rare earth element and yttrium patterns indicate that calyx shaped crystals precipitated from anoxic pore waters biomarker patterns of the carbonate beds reveal major input of lipids from prokaryotes that typically occur within layered benthic microbial mats i e cyanobacteria anoxygenic phototrophic bacteria sulphate reducing bacteria and methanogenic archaea along their length the fibrous crystals of the calyxes reveal a trend of increasing 13 c carb values from 2 7 to 3 3 suggesting that archaeal methanogenesis affected the carbonate pool apart from the putative benthic prokaryotes molecular fossils of halophilic most likely planktic archaea were detected in the carbonate beds low pristane to phytane ratios 0 8 and the presence of halophilic archaea are in accord with the lack of bioclasts and bioturbation which likely reflects increased salinities the former presence of a benthic microbial mat with cyanobacteria underlain by anoxygenic phototrophic bacteria sulphate reducing bacteria and methanogenic archaea is in accordance with studies on living microbial mats in hypersaline low oxygen marine environments the early triassic subseafloor seems to have been a sink for carbon driven by biologically induced formation of secondary diagenetic carbonate

archaeal lipids and anaerobic oxidation of methane in euxinic water columns a comparative study of the black sea and cariaco basin abstract the black sea and the cariaco basin are both large euxinic marine basins in which methane concentrations are high and where anaerobic oxidation of methane aom is an important part of the carbon cycle aom can be recognized by lipid biomarkers that are specific to methanotrophic archaea involved and by strongly 13c depleted isotope compositions consistent with uptake of 13c depleted methane derived carbon the working hypothesis for our investigation was that aom in both the black sea and cariaco basin would generate measurable diagnostic biomarkers and isotope depletions to test this hypothesis we analyzed particulate matter and surface sediments for intact glycerol dialkyl glycerol tetreaethers gdgts components of archaeal membrane lipids and measured stable carbon isotope compositions of their constituent biphytanes several gdgts and strongly 13c depleted biphytanes indicative of aom were present in the deep anoxic region of the black sea 700 m unexpectedly this biomarker signal was not detected in the upper anoxic zone of the black sea or in the entire water column of the cariaco basin even though previous studies had shown high rates of aom to occur in both basins it is possible that the aom derived biomarker signal is masked by archaeal lipids derived from non methanotrophic archaea which utilize 13c enriched carbon substrates alternately we speculate that the methanotrophic community may be highly diverse in euxinic basins possibly producing another suite of biomarkers that we did not measure this conclusion will require further testing by coordinated organic geochemical microbial ecology studies

jurassic and mid cretaceous carbonaceous claystones in the western dsdp leg 76 and eastern dsdp leg 79 north atlantic abstract deep sea drilling in the blake bahama basin dsdp leg 76 site 534 and at the mazagan escarpment off morocco dsdp leg 79 site 547 recovered carbonaceous claystones of mid cretaceous and middle late jurassic age although there are differences in the sedimentological and organic geochemical characteristics of these sediments from opposite margins of the north atlantic the preservation of the organic matter in both cases appears to be controlled by the intensity of the terrigenous organic matter supply downslope transport events and local oxygen depletion

further examples of archaeal derived hydrocarbons in mid cretaceous oceanic anoxic event oae 1b sediments abstract biomarker and total organic carbon toc analyses were carried out on laminated black shales and massive marls from the goguel level oae1a and the paquier and kilian levels oae1b of the vocontian basin of southeast france toc content was high ca 3 8 throughout the goguel the paquier and kilian levels archaeal derived hydrocarbons such as 2 6 15 19 tetramethylicosane tmi and 2 6 10 15 19 pentamethylicosane pmi were present in the oae1b sediments as reported previously kuypers m m m blokker p erbacher j kinkel h pancost r d schouten s sinninghe damste j s 2001 massive expansion of marine archaea during a mid cretaceous oceanic anoxic event science 293 92 94 however we did not detect these archaeal biomarkers in the goguel level confirming that the prevalence of archaea producing tmi and pmi was restricted to oae1b

the separated polar winter stratopause a gravity wave driven climatological feature abstract an examination of satellite derived temperatures reveals that the winter polar stratopause is usually elevated and warmer than the adjacent midlatitude stratopause this separated stratopause occurs in both hemispheres but is more pronounced and persistent in the southern winter it descends with time towards spring and exhibits week to week variability observational diagnostics and results from a two dimensional 2 d model suggest that gravity wave driving can account for this separated polar stratopause by driving a meridional circulation with downwelling over the winter pole in the model the solar heating pattern induces stronger winter westerlies than summer easterlies which leads to a stronger gravity wave driven circulation in the winter hemisphere spherical geometry and the high latitude location of the winter westerly jet combine to yield a concentrated region of downwelling model results suggest that descent of the temperature maximum with time is probably caused by wave mean f

effects of thermal maturity on biomarker distributions in gondwana coals from the satpura and damodar valley basins india abstract organic geochemistry of gondwana coals especially the distribution of molecular fossils or biomarkers is not well constrained throughout the world in this study we have therefore evaluated biomarker signatures along with bulk organic matter and petrographic characteristics in coal samples collected from two gondwana basins in india satpura basin kanhan coalfield and damodar valley basin jharia coalfield from both coalfields the samples were collected from the lower permian barakar formation which is one of the major coal bearing strata in india a significant variation in thermal maturity levels in the samples is indicated by rock eval pyrolysis and petrographic analysis with the kanhan samples generally belonging to immature to early mature stage while the jharia samples display characteristics of overmature coals this variation in the thermal maturity strongly affects the biomarker distributions especially the terpenoids hopanes and steranes were considerably degraded due to thermal maturation and were below detection limit in the overmature samples presence of aliphatic diterpanes ent 16 h kaurane 16 h phyllocladane as well as aromatic diterpanes retene methylretenes tetrahydroretene simonellite and bisnorsimonellite in low maturity samples indicate terrestrial input possibly from the primitive conifers however the aliphatic and aromatic diterpanes were below detection limit in overmature samples making it difficult to infer their source distributions of polycyclic aromatic hydrocarbons pahs are also controlled by thermal maturity levels as evident from difference in pah ratios in the low and high maturity samples

identification of aryl isoprenoids in source rocks and crude oils biological markers for the green sulphur bacteria abstract a series of c13 to c31 aryl isoprenoids 1 alkyl 2 3 6 trimethylbenzenes have been identified in reef hosted oils and their source rocks from the middle and upper silurian of the michigan basin and middle devonian of the alberta basin canada their structure has been confirmed by unambiguous synthesis of the c14 member of the series their structure and isotopic composition indicate that they are derived from isorenieratene from the chlorobiaceae family of sulphur bacteria these results are consistent with geological and geochemical studies that show that the source rocks were deposited under metahaline to hypersaline sulphate and sulphide rich water columns the distribution of other biomarkers in these oils and source rocks indicates that a diverse biota contributed organic matter to the source environment in conjunction with the aryl isoprenoids they show that there is a remarkable similarity in composition between the two sets of oils and source rocks despite their great temporal and geographic separation this reflects the similarity of their environments and emphasizes the importance of sedimentary facies in controlling the composition of organic matter in source rocks and their derived oils

composition and sources of extractable organic matter from a sediment core in lake kivu east african rift valley abstract lake kivu is a gas charged east african rift lake with currently anoxic bottom water the extractable compounds and residual organic matter of a short sediment core have 13c values typical of lacustrine microbial detritus the total extracts consist primarily of polar compounds such as n alkanoic acids hydroxyalkanoic acids triterpenoids steroids and monosaccharides with minor amounts of n alkanes and n alkanols these tracer compounds and 13c values indicate that the organic matter in the surficial and deeper sedimentary record was dominated by bacterial sources the sapropelic sediment between these horizons contains organic matter from primarily algal with lesser bacterial input terrestrial organic markers are minor in all samples the major fractions of the compounds in the total extracts were oxidized in the upper water column prior to transit through the anoxic bottom water to sedimentary deposition the sapropelic horizon may reflect lake water turnover with ventilation or hydrothermal activity and consequently increased algal blooms

rayleigh raman lidar observations of gravity wave activity from 15 to 70 km altitude over syowa 69 s 40 e the antarctic the potential energy of gravity waves gws per unit mass ep at altitudes of 15 70 km has been examined from temperature profiles obtained by a rayleigh raman rr lidar at syowa station 69 s 40 e from may 2011 to october 2013 with the exception of the summer months the gws with ground based wave periods longer than 2 h and vertical wavelengths between 1 8 and 16 km were extracted from the temperature profiles ep was larger in winter than in spring and fall although in 2012 at altitudes below 30 km ep was larger in spring than in winter and fall ep increased with a mean scale height of 11 3 km ep profiles showed a local maximum at an altitude of 20 km and a minimum at 25 km in almost every month which has not been reported by previous studies observed by radiosondes the values of ep in october of 2012 were smaller at 35 60 km and larger at 20 35 km than those in october of 2011 and 2013 this difference in the ep profile is most probably caused by different seasonal variations of zonal winds the larger and smaller ep values seem to be observed both below and above the altitude at which the zonal wind speed reached 0 m s 1 this result suggests that wind filtering of gravity waves with small phase speeds is significantly important in early spring

algal and archaeal polyisoprenoids in a recent marine sediment molecular isotopic evidence for anaerobic oxidation of methane 1 analyses of 13c contents of individual organic molecules in a marine sediment show that crocetane 2 6 11 15 tetramethylhexadecane an isomer of phytane is produced by microorganisms that use methane as their main source of carbon the sediments lie at a water depth of 68 m in the kattegat the strait between denmark and sweden crocetane appears first 185 cm below the sediment water interface in the zone marking the transition from sulfate reduction to methanogenesis its 13c value is 90 10 versus vienna pee dee belemnite vpdb its structure which includes four isoprene units arranged symmetrically around a tail to tail linkage suggests that it is produced by a member of the archaea growing at the intersection of the diffusion gradients for sulfate and methane in sedimentary pore waters the source organism apparently functions as a methane consuming member of the microbial consortium responsible for the anaerobic oxidation of methane hoehler et al 1994 in which as first demonstrated quantitatively in these sediments iversen and jorgensen 1985 electrons are transferred from methane to sulfate the presence of archaeal biomass throughout the sediment section is indicated by significant concentrations of 2 6 10 15 19 pentamethylicosane pmi and of ether bound phytane and biphytane the pmi reaches a minimum value of 47 well below the transition zone its isotopic depletion could reflect either methanogenic or methanotrophic sources the ether bound lipids are isotopically uniform throughout the section and are presumed to derive from archaea that utilize a carbon source unaffected by the oxidation of methane

a thermal and chemical degradation approach to decipher pristane and phytane precursors in sedimentary organic matter a thermal and chemical degradation approach was followed to determine the precursors of pristane pr and phytane ph in samples from the gessoso solfifera ghareb and green river formations hydrous pyrolysis of these samples yields large amounts of pr and ph carbon skeletons indicating that their precursors are predominantly sequestered in high molecular weight fractions however chemical degradation of the polar fraction and the kerogen of the unheated samples generally does not release large amounts of pr and ph additional information on the precursors of pr and ph is obtained from flash pyrolysis analyses of kerogens and residues after hydrous pyrolysis and after chemical degradation multiple precursors for pr and ph are recognised in these three samples the main increase of the pr ph ratio with increasing maturation temperature which is associated with strongly increasing amounts of pr and ph is probably due to the higher amount of precursors of pr compared to ph and not to the different timing of generation of pr and ph

debris avalanche impoundments of squamish river mount cayley area southwestern british columbia squamish river has been impounded temporarily by debris avalanches from mount cayley on numerous occasions evidence of these impoundments comes from backwater deposits and also from a cluster of in situ stumps protruding from a bar along squamish river backwater deposits consist of both lacustrine and fluvial deposits that have formed within the low energy depositional environment created by a river impoundment three main backwater deposits occur in the study area the fan toe deposit is 14 m thick and represents a single impoundment of squamish river that likely formed behind a large 4800 bp debris avalanche in situ 3200 bp stumps along squamish river probably were killed by a river impoundment due to a debris avalanche the upper terrace backwater deposit is 6 m thick and forms an aggradational terrace along squamish river which probably accumulated behind an 1100 bp debris avalanche the lower terrace deposit also forms an aggradational terrace along squamish river but represents four or possi

lidar observations of gravity wave activity in the middle atmosphere over davis 69 s 78 e antarctica a 16 month series of lidar measurements in the stratosphere and mesosphere lower thermosphere mlt region over davis station 69 s 78 e in antarctica is used to study gravity waves the unprecedentedly large number of observations totaling 2310 h allows us to investigate seasonal variations in gravity wave activity in great detail in the stratosphere the gravity wave potential energy density gwped is shown to have a large seasonal variation with a double peak in winter and minimum in summer we find conservative wave propagation to occur between 29 and 41 km altitude in winter as well as in summer whereas smaller energy growth rates were observed in spring and autumn these results are consistent with selective critical level filtering of gravity waves in the lower stratosphere in the mlt region the gwped is found to have a semiannual oscillation with maxima in winter and summer the structure of the winter peak is identical to that in the stratosphere suggesting that the gravity wave flux reaching the mlt region is controlled by the wind field near the tropopause level

the ratios of dibenzothiophene to phenanthrene and pristane to phytane as indicators of depositional environment and lithology of petroleum source rocks abstract the ratio of dibenzothiophene to phenanthrene and the ratio of pristane to phytane when coupled together provide a novel and convenient way to infer crude oil source rock depositional environments and lithologies such knowledge can significantly assist in identifying the source formation s in a basin thereby providing valuable guidance for further exploration the ability to infer this information from analysis of a crude oil is especially valuable as frequently the earliest samples in a new area may be shows and or drill stem test samples from exploratory wells which are characteristically drilled on structural highs stratigraphically remote from the source formation s a cross plot of dibenzothiophene phenanthrene versus the pristane phytane ratios measured on seventy five crude oils from forty one known source rocks ranging in age from ordovician to miocene consistently classified the oils into the following environment lithology groups marine carbonate marine carbonate mixed and lacustrine sulfate rich lacustrine sulfate poor marine and lacustrine shale and fluvial deltaic carbonaceous shale and coal the dibenzothiophene phenanthrene ratio alone is an excellent indicator of source rock lithology with carbonates having ratios 1 and shales having ratios the dibenzothiophene to phenanthrene and the pristane to phytane ratios can also be used to classify source rock paleodepositional environments the classification scheme is based on the premise that these ratios reflect the different eh ph regimes resulting from the significant microbiological and chemical processes occurring during deposition and early diagenesis of sediments the dibenzothiophene phenanthrene ratio assesses the availability of reduced sulfur for incorporation into organic matter and the pristane phytane ratio assesses the redox conditions within the depositional environment interpretation of these ratios has been aided by quantitative biomarker analysis and by carbon isotope data for pristane and phytane obtained by gas chromatography isotope ratio mass spectrometry

a molecular stratigraphic approach to palaeoenvironmental assessment and the recognition of changes in source inputs in marls of the mulhouse basin alsace france principal components analysis pca has been used to investigate changes in concentrations of the components of the hydrocarbon fractions extracted from 71 marl samples selected to cover two total organic carbon toc maxima in the lower part of the salt iv formation a lower oligocene evaporitic sequence from the mulhouse basin france the analysis indicates that the fractions can be ascribed as lying between two end member distributions the changes in these distributions are gradual suggesting that they resulted from fairly gradual changes in the depositional palaeoenvironment these changes are related to increased algal productivity associated with the evolution of a restricted lacustrine environment through to one with a greater marine influence systematic variations in the concentrations of selected components relative to the toc profile point to a repeated sequential evolution in the biological assemblage during deposition of the sequence

archaeal and bacterial lipids in authigenic carbonate crusts from eastern mediterranean mud volcanoes abstract we investigated the distributions and 13 c values of lipid biomarkers in authigenic methane related carbonate crusts formed on eastern mediterranean mud volcanoes a highly diverse suite of microbial membrane lipids was detected strongly 13 c depleted lipids diagnostic for archaea include isoprenoid glycerol diethers isoprenoid glycerol dialkyl glycerol tetraethers and several c 20 c 35 isoprenoid hydrocarbons bacterial lipids mainly consist of dialkyl glycerol diethers branched fatty acids and hopanoids showing important 13 c depletions albeit less than archaeal lipids the data provide further evidence for the involvement of archaea and bacteria in the anaerobic oxidation of methane aom and in the sequestration of methane derived carbon in authigenic carbonate crusts varying distributions and isotopic compositions of 13 c depleted lipids argue for heterogeneous aom related microbial consortia expanding on existing work at cold seeps distinctive biomarker features and inferred microbial assemblages are observed in these crusts in agreement with available phylogenetic data for the samples our results support the potential of lipids for distinguishing methanotrophic communities despite the observed variances conservative features in the abundances and isotopic offsets of microbial biomarkers occur likely reflecting the overall relationships between archaea and bacteria and the nature of carbon flow between them

variability of early diagenesis in lake sediments evidence from the sedimentary geolipid record in an isolated tarn abstract a 0 5 m long core of sediment from coburn mountain pond maine u s a has provided a virtually undisturbed and continuous record of sediment deposition for the last 200 yr in this small essentially pristine tarn organic carbon concentrations c n ratios carbon isotopic compositions and extractable hydrocarbon molecular compositions indicate subtle differences in the sources of organic matter between sediments deposited before and after ca 1950 but are otherwise constant in contrast total concentrations and molecular distributions of n fatty acids and n alkanols vary considerably the fatty acid and alkanol geolipid fractions are both sensitive to early diagenetic alteration yet the two fractions react differently concentrations and compositional parameters such as long short even odd and branched unbranched ratios fluctuate with sediment depth and reflect amounts of microbial reworking which have varied repeatedly over the depositional history n alkane distributions are relatively unaffected by the short term changes and therefore better preserve the history of biolipid sources to the sediments

petroleum geochemistry of cretaceous outcrops from the calabar flank southeastern nigeria abstract a combined geochemical and molecular characterisation of a wide section of cretaceous outcrop sedimentary rocks with no significant effects of weathering from the calabar flank southeastern nigeria has been undertaken for petroleum potential evaluation rock eval pyrolysis and lipid biomarkers show organic matter om to contain varying proportions of marine and continental materials om content in the samples is variable low values of total organic carbon toc ranging from 0 01to 9 49 with varying extractability 44 4215 ppm low hydrogen indices hi 10 190 mg hydrocarbons hc g toc tmax in the range 414 c 460 c and vitrinite reflectance values from 0 41 to 0 47 ro were obtained indicating immature to marginally mature terrestrially derived om of type iii kerogen awi formation of aptian middle albian age with an average genetic potential of 4 3 kg hc ton rock has the highest potential for oil gas 13c 12c ratios of the kerogen biomarker distribution pattern and some specific compound ratios ts tm oleanane c30 hopane c31 22s 22r 22s homohopane and moretane c30 hopane are useful in determining the source and thermal maturity of the om the coniacian campanian maastrichian black shales of new netim and nkporo formations differ significantly from other formations because of the presence of oleanane which may serve to delineate the late upper cretaceous boundary

organic geochemistry of cretaceous black shales from the galicia margin ocean drilling program leg 103 organic carbon rich black shales from three different cretaceous episodes sampled during ocean drilling program leg 103 have been studied by organic geochemical methods rock eval analysis carbon isotope data and lipid biomarkers show organic matter to contain varying proportions of marine and continental materials in hauterivian barremian organic carbon rich turbiditic marlstones major amounts of land derived organic matter are found aptian albian black colored shales are interspersed within green claystones from which they differ by containing more marine organic matter an abbreviated layer of black shale from the cenomanian turonian boundary is dominated by well preserved marine organic matter downslope transport and rapid reburial within a predominantly oxygenated dcepwater setting created most of these examples of black shales except for the cenomanian turonian deposits in which decpwater anoxia may have been involved

anaerobic bacterial degradation of pristenes and phytenes in marine sediments does not lead to pristane and phytane during early diagenesis abstract anaerobic degradation of mixtures of isomeric pristenes and phytenes by sedimentary bacterial communities was investigated these isoprenoid alkenes were quickly metabolized without formation of the corresponding alkanes identification of several bacterial metabolites allowed us to confirm the key role played by hydration in the metabolism of alkenes despite the increasing production of 5 stanols during incubation attesting to the involvement of biohydrogenation this process did not act significantly on the double bond of pristenes and phytenes their resistance is attributed to the lack of binding polar group s to anchor the substrate to the enzyme and thus allow the double bond to reach the reductive catalytic site it therefore seems that microbial hydrogenation of pristenes and phytenes does not account for the presence of pristane and phytane in recent sediments during early diagenesis

lidar observations of persistent gravity waves with periods of 3 10 h in the antarctic middle and upper atmosphere at mcmurdo 77 83 s 166 67 e persistent dominant and large amplitude gravity waves with 3 10 h periods and vertical wavelengths 20 30 km are observed in temperatures from the stratosphere to lower thermosphere with an fe boltzmann lidar at mcmurdo antarctica these waves exhibit characteristics of inertia gravity waves in case studies yet they are extremely persistent and have been present during every lidar observation we characterize these 3 10 h waves in the mesosphere and lower thermosphere using lidar temperature data in june from 2011 to 2015 a new method is applied to identify the major wave events from every lidar run longer than 12 h a continuous 65 h lidar run on 28 30 june 2014 exhibits a 7 5 h wave spanning 60 h and 6 5 h and 3 4 h waves spanning 40 and 45 h respectively over the course of 5 years 323 h of data in june reveal that the major wave periods occur in several groups centered from 3 5 to 7 5 h with vertical phase speeds of 0 8 2 m s these 3 10 h waves possess more than half of the spectral energy for 93 of the time a rigorous prewhitening postcoloring technique is introduced for frequency power spectra investigation the resulting spectral slopes are unusually steep 2 7 below 100 km but gradually become shallower with increasing altitude reaching about 1 6 at 110 km two dimensional fast fourier transform spectra confirm that these waves have a uniform dominant vertical wavelength of 20 30 km across periods of 3 5 10 h these statistical features shed light on the wave source and pave the way for future research

rayleigh lidar observations of gravity wave activity in the winter upper stratosphere and lower mesosphere above davis antarctica 69 s 78 e 1 gravity wave activity in the upper stratosphere and lower mesosphere uslm is investigated using temperature data retrieved from a rayleigh lidar at davis antarctica 69 s 78 e during the 2007 and 2008 winters the temporal and height variabilities of waves with ground based periods greater than 2 h and vertical wavelengths between 4 km and 20 km are analyzed stratospheric gravity wave potential energy per unit mass shows a weaker correlation with stratospheric winds at davis than that reported in the arctic gravity waves dissipate above 40 km during winter while there is no dissipation in the autumn mesosphere a separate analysis of gravity waves with ground based periods of 2 6 h revealed lower dissipation in the winter mesosphere the seasonal cycle of gravity wave activity is evident throughout the uslm with peak activity observed during winter the gravity wave potential energy and vertical wavenumber power spectral density at davis are similar to that recorded at other high latitude sites

hydrogen isotope ratios of aliphatic and diterpenoid hydrocarbons in coals and carbonaceous mudstones from the liaohe basin china abstract hydrogen isotope compositions of the aliphatic and diterpenoid hydrocarbons were determined for five coal and carbonaceous mudstone samples collected from drilling cores 1531 1767 m depths in the liaohe basin china the bulk organic materials were mainly derived from terrestrial higher plants d values for most of the n alkanes varied from 150 to 220 and were not significantly different among the samples pristane was 34 69 depleted in d relative to phytane both pristane and phytane however had the same trend of variation in d from sample to sample diterpenoids were on average 49 81 depleted in d relative to the n alkanes variations in d also occurred between different diterpenoids indicating a different source for these compounds an enrichment process for the heavy hydrogen isotope was observed as expected when a compound was progressively altered through diagenesis especially the dehydrogenation process overall d and 13c showed distinct patterns between structurally different lipid classes although possible hydrogen exchange cannot be completely excluded during maturation our results further support the notion that hydrogen isotopes of lipid biomarkers from ancient sediments can be used to assess the origin of the organic matter to determine oil source rock correlation and perhaps to reconstruct the paleoenvironment under which the organic material was deposited

rayleigh lidar observations of thermal structure and gravity wave activity in the high arctic during a stratospheric warming abstract during february and march 1993 rayleigh lidar observations of temperature structure and gravity wave activity were carried out in the high canadian arctic at eureka northwest territories 80 n 86 w a sudden warming was observed first in the upper stratosphere during late february and then at lower levels in early march the warming appeared to be part of a disturbance of the entire middle atmosphere with temperature changes in the mesosphere and lower stratosphere being opposite in sign to those in the upper stratosphere shorter time and length scale temperature fluctuations observed in the upper stratosphere are interpreted as being a result of atmospheric gravity waves the wave amplitudes are shown to be capable of inducing convective instability the rms perturbation and available potential energy density show substantial vertical and day to day variability in regions of conservative and dissipative growth rates vertical growth of the potential energy spectral density is seen to ceas

geochemical characterization of malm zeta laminated carbonates from the franconian alb sw germany ii abstract during jurassic times especially within the malm stage local depressions formed on the eastern bavarian carbonate platform that were surrounded by wall reefs this created a unique depositional environment where in an open marine setting stagnant and anoxic bottom waters developed in an intra reef depression anoxic conditions were stabilized below wave base by enhanced salinity in the bottom waters and establishment of a density stratification biomarker analysis was applied to characterize palaeosalinity and redox conditions utilizing organic sulfur compound methylated chroman hopanoid and saturated isoprenoid distributions prevention of terrigenous influx by protecting reef walls lead to iron deficiency in intra reefal sediments causing early diagenetic sulfurization of functionalized lipids absence of clay mineral catalysts and early sulfurization favored an unusual steroid distribution lacking rearranged analogues but providing coexistence of saturated steranes with and configuration 13 17 spirosterenes unknown sterenes and steradienes as well as mono di and triaromatic steroids desulfurization of the polar fraction was carried out for two samples to verify that palaeoenvironment reconstruction based on free hydrocarbon and heterocompound distribution was not invalidated by sulfur quenching of selected compounds gammacerane was found to be the only component to occur exclusively in the sulfur bound fraction only minor amounts of hydrocarbons were released upon desulfurization implying that free bitumen analysis was applicable for organofacies characterization organic petrological investigation of organic mats revealed the presence of two different types of such structures comparison of organoclast fluorescence spectra with those of extracted porphyrin fractions indicate an origin of porphyrins exclusively from cyanobacterial mats whereas algal dominated mats yield no porphyrins this aims towards a better localization of specific biomarker origin in geological samples

first biomarker evidence for methane oxidation at cold seeps in the southeast atlantic regab pockmark abstract sediment cores from the regab pockmark an active cold seep area in the southeast atlantic were analysed for their lipid biomarker distribution and associated stable carbon isotopic composition substantial amounts of diagnostic archaeal lipids were found consisting mainly of archaeol sn 2 hydroxyarchaeol and crocetane all archaeal lipids were profoundly depleted in 13c with 13c values as low as 133 concurrently abundant monoalkylglycerolethers mage assigned to sulphate reducing bacteria were identified and showed strong 13c depletions 13c between 86 and 95 the structural and isotopic patterns of these microbial lipids provided compelling evidence for anaerobic oxidation of methane aom occurring in regab sediments mediated by archaea and sulphate reducing bacteria lipid fingerprints indicated that anaerobic methanotrophic archaea anme 2 and sulphate reducing bacteria from the desulfosarcina desulfococcus cluster are the dominant aom assemblages depth profiles implied that highest aom takes place below the upper 2 cm mainly in the 6 12 cm depth interval significant abundances of 13c depleted diploptene and 4 methylsterols were found as well inferring that aerobic methanotrophy occurs in the surface sediment interval this first biomarker study at the recently investigated cold seeps in the se atlantic expand on existing work on aom settings and add new evidence for aerobic and anaerobic methanotrophic communities occurring in close vicinity

catagenesis of light acyclic isoprenoids in petroleum abstract the article presents three sets of experimental data related to the subject of the alteration of light acyclic isoprenoid alkanes in petroleum a distributions of c 9 c 20 isoprenoids in crude oils and oil shales b thermocracking reaction studies of oil shales and c thermocracking of three individual isoprenoids pristane phytane and squalane in a pure state and in the presence of acidic minerals a combination of the data is used as a basis of a hypothesis that most c 9 c 16 acyclic isoprenoids were formed in the latest stage of petroleum catagenesis in a sequence of thermo radical and acidic clay catalyzed cracking reactions of heavier isoprenoid precursors mostly pristane and phytane

diagenesis and distribution of acyclic isoprenoid hydrocarbons in late miocene to pliocene marine siliceous rocks from horonobe hokkaido japan abstract a sequence of late miocene to pliocene siliceous mudstones from boreholes hdb 3 and hdb 4 from horonobe hokkaido japan is homogeneous and useful for the study of diagenetic degradation and transformation of sedimentary organic matter using these siliceous mudstones the diagenetic change in acyclic isoprenoid hydrocarbons was investigated the palaeotemperatures of the samples were estimated to be in the range 30 60 c on the basis of the silica mineral transformation and the present day geothermal gradient in the region the relative abundances of pristane to pristenes and phytane to phytenes increase drastically with depth the remarkable changes in pristane pristene and phytane phytene occur in a temperature range of about 35 50 c the relative abundances could be potential parameters for palaeotemperature analysis of immature sedimentary rocks remarkable increases in pristane and phytane concentration with maturity show that in addition to extractable free pristenes and phytenes bound acyclic isoprenoids are the major source of pristane and phytane pristane phytane and pristenes phytenes are nearly constant through the entire boreholes showing that the relative abundance of the precursor c 19 c 20 acyclic isoprenoids was determined at the time of deposition and or in the early stage of diagenesis pristene phytene as well as pristane phytane could be useful parameters for assessing palaeodepositional environment

11 years of rayleigh lidar observations of gravity wave activity above the southern tip of south america gravity wave gw activity is analyzed using temperature t data retrieved from a rayleigh lidar at rio gallegos argentina 51 6 s 69 3 w gw characteristics are derived from 302 nights of observations providing more than 1018 h of high resolution lidar data between 20 km and 56 km height from august 2005 to december 2015 t measurements are performed by a differential absorption lidar dial instrument this lidar was the southernmost outside antarctica until the end of 2017 rio gallegos is an exceptional place to observe large amplitude gw every lidar measurement is classified according to its relative position to the polar vortex the lidar measurements are compared with collocated sounding of the atmosphere using broadband emission radiometry saber and global positioning system radio occultation gps ro data the different instruments show different windows of the gw spectrum providing complementary observations in general the geometric mean of the specific gw potential energy pe is larger during winter and spring than during summer and autumn the largest geometric mean of pe is found inside the vortex and decreases monotonically at its edge outside it and when there is no vortex the same behavior is observed with satellite data on average it can be seen that lidar observations provide larger pe values than limb sounding measurements from a morlet continuous wavelet transform analysis 3 distinct modes are captured from saber and from gps ro data at the upper and lower stratosphere respectively in particular a systematic 3 5 4 years oscillation possibly related to el nino southern oscillation is observed

petroleum geology and geochemistry of the middle proterozoic mcarthur basin northern australia iii composition of extractable hydrocarbons abstract middle proterozoic organic rich sediments from the mcarthur basin in northern australia contain abundant hydrocarbons which are derived from syngenetic kerogen and hence are representative of the organic remains of microorganisms living at that time the major classes of hydrocarbons identified were n alkanes monomethyl branched alkanes cyclohexyl alkanes and acyclic isoprenoids there were also low abundances of pentacyclic triterpanes comprising hopanes and methyl hopanes low concentrations of steranes were present in most samples but like the triterpanes they were only easily detected in the least thermally altered sediments and hence were of limited use in detailed assessments of thermal maturity the presence of steranes in sediments of this age is strong evidence for the existence of eukaryotic organisms as far back as 1690 ma although the relatively high abundances of branched alkanes indicates that most of this primitive organic matter was probably derived from prokaryotes