can biomass burning produce a globally significant carbon isotope excursion in the sedimentary record negative carbon isotope excursions have been comprehensively studied in the stratigraphic record but the discussion of causal mechanisms has largely overlooked the potential role of biomass burning the carbon isotopic ratios 13 c of vegetation soil organic matter and peat are significantly lower than atmospheric carbon dioxide co2 and thereby provide a source of low 13 c co2 when combusted in this study the potential role of biomass burning to generate negative carbon isotope excursions associated with greenhouse climates is modeled results indicate that major peat combustion sustained for 1000 yr increases atmospheric co2 from 2 5 present atmospheric levels pal to 4 6 pal and yields a pronounced negative 13 c excursion in the atmosphere 2 4 vegetation 2 4 and the surface ocean 1 2 but not for the deep ocean 0 9 release of co2 initiates a short term warming of the atmosphere up to 14 4 c with a duration of 1628 yr which is consistent with the magnitude and length of an observed toarcian excursion event these results indicate that peat combustion is a plausible mechanism for driving negative 13 c excursions in the rock record even during times of elevated pco2

on the similarity of lower stratospheric potential vorticity dipoles above tropical and midlatitude deep convection abstractsimulations of the effects of deep convection on the structure of potential vorticity pv in the upper troposphere and lower stratosphere utls have shown that a common signature in the presence of ambient horizontal vorticity is a horizontal pv dipole here the relationship between convection and pv structures in the utls in tropical cyclone talas and the extratropical super tuesday cyclone is investigated with the university of wisconsin nonhydrostatic modeling system uwnms dipoles of potential temperature in the utls are interpreted as an upward deflection of the ambient flow over the updraft cold followed by subsidence in its lee warm aligned with the wind direction pv dipoles larger than 20 pv units 1 pvu 10 6 k kg 1 m2 s 1 are identified with typical vertical and horizontal extents of 3 and 200 km respectively and lifetimes up to 12 h confirming the findings of chagnon and gray it is found that horizontal pv dipoles are related to vortex tilting where horizontally

the pre quaternary history of fire abstract although evidence for land vegetation comes from the silurian and maybe even earlier the first record of fossil charcoal fusain is from the late devonian for this period there are only one or two isolated records not until the early carboniferous is there a record of extensive charcoal deposits mainly preserved in near shore clastic sediments which provide evidence of significant and widespread wildfires by the late carboniferous charcoal was common or abundant in a wide range of facies including tropical wetland peats wildfire played an important role in shaping the environment at this time the latest palaeozoic and early mesozoic records of charcoal are fewer whereas important deposits of late mesozoic age are found worldwide the occurrence of charcoal at the cretaceous tertiary boundary has been highlighted as evidence for a global fire following a meteorite impact but this interpretation is questionable charcoal has been widely reported from tertiary sediments and its appearance in the quaternary and recent is not solely as a result of human impact through the past 400 million years there have been major changes in atmospheric oxygen levels that affected fire intensity and frequency fire systems thus have a long history and their impact on shaping the environment is assessed

properties origin and nomenclature of rodlets of the inertinite maceral group in coals of the central appalachian basin u s a abstract resin rodlets sclerenchyma strands and woody splinters which are collectively called rodlets were studied by chemical optical petrographic and scanning electron microscopic sem techniques a study was made of such rodlets from the bituminous coal beds of the central appalachian basin pennsylvanian upper carboniferous of the united states comparisons were made with rodlets from coal beds of the illinois basin the southern anthracite field of pennsylvania the st rose coal field of nova scotia and european and other coal fields in order to determine their physical and chemical properties a detailed study was made of the rodlets from the pomeroy coal bed high volatile a bituminous coal monongahela formation upper pennsylvanian of kanawha county west virginia the origin of the rodlets was determined by a comparative analysis of a medullosan seed fern stem from the herrin no 6 coal bed high volatile c bituminous coal carbondale formation from washington county illinois rodlets are commonly concentrated in fusain or carbominerite layers or lenses in bituminous coal beds of the central appalachian basin most of the rodlets examined in our study were probably derived from medullosan seed ferns the three types of rodlets are distinguished on the basis of cellularity morphology and fracture the resin rodlets studied by us are noncellular and appear to be similar in properties and origin to those found in coal beds of the middle and upper pennsylvanian of the illinois basin the resin rodlets extracted from the pomeroy coal bed exhibit high relief and high reflectance when polished and viewed in reflected light they are opaque in transmitted light in cross section the resin rodlets are oval to round and have diameters ranging from 60 to 450 m many are solid but some have vesicles canals or cavities which are commonly filled with clay probably kaolinite typically they have distinct fracture patterns kerfs in longitudinal and cross sections and many are characterized by dense probably oxidized rims the orientation and amounts of void space and mineralization of resin rodlets in coal have resulted in much confusion in their recognition and classification the resin rodlets are petrographically recognized as sclerotinites of the inertinite maceral group we here propose that resin rodlets be assigned to the maceral variety of sclerotinites termed resino sclerotinite because of their presumable resinous origin other investigators have confused some fusinitized resin rodlets with fungal masses which have different morphological properties and which probably have different chemical properties we here propose that such fungal masses be assigned to the maceral variety of sclerotinites termed fungo sclerotinite the sclerenchyma strands examined in our study are cellular thick walled and crescent shaped in cross section they exhibit high reflectance and high relief and belong to semifusinite and fusinite of the inertinite maceral group sclerenchyma strands are commonly associated with resin canals in medullosa and related seed fern genera which are common in coal balls of the illinois basin we here propose adoption of the maceral varietal terms sclerenchymo fusinite and sclerenchymo semifusinite for these bodies the woody splinters in the pomeroy coal bed are cellular and thin walled and have scattered pits as much as a few microns in diameter they are dark brown to black in transmitted light and commonly have a lower reflectance than the resino sclerotinite and sclerenchymo fusinite of the pomeroy coal the woody splinters belong to semifusinite and fusinite of the inertinite maceral group the maceral varietal terms xylemo semifusinite and xylemo fusinite are here proposed for these bodies elemental chemical data for the resin rodlets of the pomeroy coal bed of the central appalachian basin indicate that resin rodlets have significantly lower atomic h c and o c ratios than do sclerenchyma strands and woody splinters the lower atomic h c and o c ratios of the resin rodlets correlate with the highest reflectance in the coal ball medullosan seed fern stem from the herrin no 6 coal bed of the illinois basin the reflectances of the resin rodlets woody splinters and sclerenchyma strands are similar and comparable to those of associated vitrinite in the coal ball stem and in the attached coal however resin rodlets and sclerenchyma strands in the attached coal have significantly higher reflectances similar to those of the pomeroy coal

water column euxinia and wildfire evidence during deposition of the upper famennian hangenberg event horizon from the holy cross mountains central poland a palynological study of the uppermost famennian section from kowala quarry holy cross mountains central poland allowed recognition of two miospore zones lv retispora lepidophyta apiculiretusispora verrucosa and ln retispora lepidophyta verrucosisporites nitidus based on palynology and sedimentology the black shale within the upper part of the section is identified as equivalent to the hangenberg black shale which is known globally this black shale contains compounds characteristic of photic zone euxinia including isorenieratane and its derivatives such compounds are absent in the organic poor marls and shales occurring below the ln zone and are present only as traces in the layers just above the black shale indicating fluctuations in the oxygen minimum zone during uppermost famennian sedimentation palynofacies show high amounts of amorphous organic matter and prasinophyte concentrations in the black shale and a subsequent significant decrease of amorphous organic matter concomitant with a rapid increase of terrestrial input mainly miospores with common tetrads in the layers above the black shale this supports the relatively rapid change in the taxonomic composition of phytoplankton caused by fluctuations of the chemocline the whole succession corresponds to one sea level rise and fall the presence of high concentrations of peri condensed polycyclic aromatic hydrocarbons and large amounts of small charcoal particles at the hangenberg event horizon indicate the occurrence of wildfires such observations suggest that atmospheric o2 levels had exceeded the critical threshold of 13 above which wildfires may occur by latest famennian time

source apportionment of the hydrocarbon background in sediment cores from hecate strait a pristine sea on the west coast of british columbia canada abstract significant reserves of oil and gas have been predicted for hecate strait a pristine semi enclosed sea on the continental shelf adjacent to british columbia on the west coast of canada to establish a baseline for the natural background of hydrocarbons in sediment prior to any further offshore oil and gas development or increase in oil tanker traffic in the hecate strait region three sediment box cores were collected along a west to east transect across southern hecate strait in september 2003 210 pb measurements established that the bottom sections date to 1920 pre 1800 and 1870 respectively which predate any significant industrial development on the coast alkane and polycyclic aromatic hydrocarbon pah concentrations are low in most sediment samples and both the concentrations and fluxes differ little between surface and bottom core sections pah profiles exhibit a dominance of alkyl pahs for each alkyl pah homologous series with varying amounts of parent unsubstituted pahs while alkane chromatograms show no unresolved complex mixture ucm and there is little change in composition between present day and pre 1800 sediments for most parameters principal components analysis pca models and pah and biomarker ratios indicate that composition patterns are consistent with low and varying natural petrogenic and pyrogenic inputs with little or no anthropogenic input the most likely primary source of petrogenic pahs to the sediments is cenozoic lignites from the skonun formation which outcrops on haida gwai and underlies most of hecate strait two subsurface sections deposited in 1990 and 1930 in the core from milbanke sound on the east side of the transect have elevated concentrations for the alkyl phenanthrene anthracenes and dibenzothiophenes with no ucm and most likely also have a source in immature coal this study suggests that the hecate strait environment has low hydrocarbon concentrations with an apparent minor role for oil seeps and a likelihood that most of the petrogenic pah sources are shales or immature coals with limited pah bioavailability if these characteristics are representative of hecate strait sediments overlying the queen charlotte basin it may mean that biota are likely unadapted to the presence of oil and thus would be more sensitive to exposure to oil from an oil spill than those in a more impacted environment

evidence of multiple late bashkirian to early moscovian pennsylvanian fire events preserved in contemporaneous cave fills abstract during a low sea level stand and wet climate phase at the end of the mississippian lower palaeozoic limestones at the northern edge of the illinois basin were karstified the caves and fissures that formed were infilled subsequently with clastic sediments of pennsylvanian age late bashkirian early moscovian atokan duckmantian bolsovian westphalian b c the earliest infills comprise organic rich almost coaly sediments while sands silts and fine clays were deposited subsequently the sediments are fossiliferous and contain abundant plant fragments most notably cordaitalean and conifer remains many of the plants and megaspores are uncompressed and have undergone minimal thermal alteration charcoal occurs throughout the sedimentary infills but is most abundant in the later deposits where conifer remains predominate these conifers are currently amongst the oldest known from north america the presence of cordaitalean remains in the earliest coaly infills is supported by the detection of specific fernane derivatives the lipid extract of the cave fill sequence contains polyaromatic hydrocarbons pahs such as pyrene chrysene benzo ghi perylene and coronene which distribution further attests to the importance of wildfire in preserving the plant remains

esr dating of pleistocene mammals and marine shells from the coastal plain of rio grande do sul state southern brazil abstract the coastal plain of rio grande do sul state cprs in southern brazil encompasses four barrier lagoon depositional systems formed by marine highstands during the quaternary but the ages of the pleistocene systems older than 125 ka are not precisely known due to the lack of numerical dates in order to refine the chronology of these deposits several fossils of terrestrial mammals collected in the fluvial facies of the lagoon system iii and fossil shells from the marine facies of the barrier system ii exposed in the southern sector of the cprs were subject to dating by electron spin resonance esr the ages of the mammalian remains range from 90 10 to 43 3 ka thus representing the last glacial cycle mis 4 and 3 the mean eu age of the shells is 224 24 6 ka but this value is considered younger than the real age because of excessive uranium uptake observed among the younger shells an estimated mean age of some 235 238 ka would agree with other esr and tl ages obtained for fossils and sediments collected from beds overlying the shells and would be consistent with the sea level highstand at the early mis 7 substage 7e the presence of bivalves and foraminifers that indicate ocean temperatures higher than at present seems to corroborate this estimate given that mis 7e was characterized by hypsithermal conditions

the last 50 000 years in the neotropics southern brazil evolution of vegetation and climate abstract in the lagoa campestre lake of salitre 19 s 46 46 w 970 m elev there are plant taxa belonging to many ecological groups that are encountered nowhere else at this latitude frequent incursions of polar advections causing cooling and humidity a cool and foggy climate in the middle of the depression and warmer temperatures on the surrounding slopes help to maintain all these groups within a fairly restricted area late pleistocene holocene climatic change has had a considerable impact on the flora and vegetation of salitre the pollen record of the 6 m deep core lc3 shows how cold forest trees such as araucaria angustifolia and drimys brasiliensis semi deciduous forest halophytic plants and peat bog started to develop on this site the initial period between c 50 000 and 40 000 yr b p was an arid phase not recorded in any other neotropical lowland site it was followed by a period of high moisture levels 40 000 to 27 000 yr b p with a maximum estimated at c 35 000 yr b p the late glacial maximum is missing because of a gap in sedimentation humidity gradually increased during the late pleistocene between 16 000 and 11 000 yr b p the early holocene 9500 to 5000 yr b p is characterized by a more marked seasonal pattern and higher temperatures reaching a maximum c 5000 yr b p the spread of semi deciduous forest between 4000 and 3000 yr b p attests to a return of humidity comparison with the serra negra section 19 s 46 45 46 w 1170 m elev not far from salitre confirms the high moisture rates recorded at c 35 40 000 yr b p although temperatures were cooler at the altitude of serra negra as is attested by the presence of araucaria forest and also confirms the strong impact of polar advections on the climate of southeastern brazil

how marine isotope stage 3 mis3 is reflected in northern mesopotamia faunal assemblage of argentina the xenarthra cingulata case mis 3 60e25 ka corresponds to a long interstadial episode considered generally warmer than mis 2 and 4 and including numerous and abrupt dansgaardeoeschger and heinrich events sometimes brief but very intense the materials studied here coming from the late pleistocene exposures in central north mesopotamia corrientes province argentina toropi yupoi fm mis 3 ca 5 2e36 ka is characterized by the presence of a large and complex vertebrate assemblage being the cingulata xenarthra one of the most frequently represented taxa in this work we provide an updated list of cingulates from corrientes province referrable to the late pleistocene after performing new collections in the area and revising previous determinations this includes a dasypodidae propraopus sulcatus lund euphractus aff euphractus sexcinctus linnaeus chaetophractus villosus desmarest b pampatheriidae holmesina paulacoutoi cartelle guerra and mahecha bohorquez pampatherium sp pampatherium typum ameghino c glyptodontidae panochthus tuberculatus owen panochthus sp glyptodon reticulatus owen glyptodon sp neosclerocalyptus paskoensis zurita neosclerocalyptus cf n paskoensis zurita neosclerocalyptus sp the paleoenvironmental context that may be inferred from the palaeofaunal particularly from the diversity of cingulates in the quaternary of corrientes province is characterized by alternating cold arid or semiarid pulses and warmer humid ones generating new evidence related to mis 3 even though the taxa recorded are not new the relative occurrence of each one shows evident differences with those in other areas using this information the diversity of cingulates is compared to that of late pleistocene faunas described for sediments from areas currently located in the provinces of formosa and buenos aires argentina northern uruguay and southern brazil lastly palaeoclimatic and palaeobiogeographic aspects that may be inferred from the study of this assemblage are discussed in the context of the mis 3

a review of the biogeochemical controls on the occurrence and distribution of polycyclic aromatic compounds pacs in coals abstract the organic matter in coal contains polycyclic aromatic compounds pacs of varying quantities in diverse soluble and insoluble forms pacs in coal are of special interest for organic geochemical studies because they have been successfully used as biological marker compounds biomarkers and indicators of thermal maturity in addition they could provide critical information to understand the structural and compositional evolution of the coal organic matters during coalification and to predict pac releasing characteristics during coal utilization the main purpose of this paper is to provide a critical review on the current state of knowledge on the potential use of pac composition to understand the underlying biogeochemical factors that control pac occurrence and distribution in coal the published pac data of world coal are first compiled according to their ranks natural coke anthracite semi anthracite bituminous coal low volatile bituminous coal medium volatile bituminous coal high volatile bituminous coal sub bituminous coal lignite countries brazil canada china france germany japan usa formation periods carboniferous permian jurassic cretaceous early middle cenozoic then the biogeochemical factors affecting the occurrence and distribution of pacs in coal including biogenic precursor materials coal rank maceral composition depositional environment and geological settings are comprehensively reviewed the results show that the geochemical parameters of pacs in coal are robust tools to trace the coalification processes from the molecular perspectives and to understand the corresponding biogeochemical process e g depositional environment geological settings igneous intrusion occurring during coal formation

observations on the nature and origin of fusain abstract evidence for a wildfire origin of fusain is examined charcoal produced by natural fires and artificial charring resembles fossil fusain both in physical size and shape and in optical reflectance artificially charred leaves and naturally burnt wood are illustrated using the sem reflectance studies on modern charcoals suggest that much semifusinite may be produced by pyrolysis the ecological implications of a wildfire origin of fusain are discussed and it is concluded that fires have been a feature of terrestrial ecosystems from at least the late devonian

precise radiocarbon dating of late glacial cooling in mid latitude south america abstract variability of atmospheric 14c content often complicates radiocarbon based chronologies however specific features such as periods of constant 14c age or steep changes in radiocarbon ages can be useful stratigraphic markers the younger dryas event in the northern hemisphere is one of those periods showing conspicuous 14c wiggles although the origin of those variations is not fully understood we can make practical use of them and determine i whether the younger dryas was global in extent if so ii were the initial cooling and the final warming synchronous worldwide and iii what are the implications of these similarities differences here we report high resolution ams 14c chronologies from the mid latitudes of south america that pinpoint a cool episode between 11 400 and 10 20014c yr b p the onset of the final cool episode of the late glacial in the southern mid latitudes i e the huelmo mascardi cold reversal preceded the onset of the younger dryas cold event by 550 calendar years both events ended during a radiocarbon age plateau at 10 20014c yr b p thus the huelmo mascardi cold reversal encompasses the younger dryas as well as a couple of short term cool warm oscillations that immediately preceded its onset in the north atlantic region

wildfires and seasonal aridity recorded in late cretaceous strata from south eastern arizona usa lithostratigraphic and organic chemostratigraphic studies of fluvial lacustrine sediments in the late cretaceous fort crittenden formation in south eastern arizona usa reveal changes in palaeoclimate and tectonics as well as associated fluctuations in lake level the lower fort crittenden is dominated by marginal wetland to deep water lake deposits whereas the upper fort crittenden is characterized by wetland to deltaic deposits abundance of polycyclic aromatic hydrocarbons pah and reflectance of fusinite substantiate the impact of wildfires within the watershed organic geochemical evidence of wildfires is linked with sedimentological indicators of seasonal aridity suggesting that wildfires were common occurrences sedimentological evidence for seasonal aridity includes mottles and pseudoslickensides on ped structures within wetland mudstones distinct variations in pah assemblages characterized by the number of aromatic rings indicate that there were variations in the intensities of wildfires assuming no variations in the types of fuel fusinite reflectance values are consistent with combustion temperatures from 470 to 550 c observed in modern wildfires

comment on the kaiho et al paper a forest fire and soil erosion event during the late devonian mass extinction palaeogeography palaeoclimatology palaeoecology 392 2013 272 280 abstract kaiho et al 2013 palaeogeography palaeoclimatology palaeoecology 392 2013 272 280 interpreted the occurrence of elevated concentrations of high molecular weight polycyclic aromatic hydrocarbons and dibenzofuran as indicators of wildfires and enhanced run off near the frasnian famennian f f boundary we argue that other processes including weathering or hydrothermal oxidation not discussed by kaiho et al led to the observed increase in the concentration of these compounds and also changed their distribution kaiho et al s evidence for soil erosion and eutrophication induced euxinia is also weak in the case of the investigated belgian sections finally kaiho et al rather unfortunately omitted a great wealth of important data published elsewhere choosing instead to include only those which support their ideas and interpretations

organic markers as source discriminants and sediment transport indicators in south san francisco bay california sediment samples from nearshore sites in south san francisco bay and from streams flowing into that section of the bay have been characterized in terms of their content of biogenic and anthropogenic molecular marker compounds the distributions input sources and applicability of these compounds in determining sediment movement are discussed by means of inspection and multivariate analysis the compounds were grouped according to probable input sources and the sampling stations according to the relative importance of source contributions a suite of polycyclic aromatic hydrocarbons pahs dominated by pyrene fluoranthene and phenanthrene typical of estuarine environments worldwide and suites of mature sterane and hopane biomarkers were found to be most suitable as background markers for the bay a homologous series of long chain n aldehydes c12 c32 with a strong even over odd carbon number dominance in the higher molecular weight range and the ubiquitous n alkanes n c24 c34 with a strong odd over even carbon number dominance were utilized as terrigenous markers several ratios of these terrigenous and bay markers were calculated for each station these ratios and the statistical indicators from the multivariate analysis point toward a strong terrigenous signal in the terminus of south bay and indicate net directional movement of recently introduced sediment where nontidal currents had been considered to be minimal or nonexistent and tidal currents had been assumed to be dominant

the role of vortical hot towers in the formation of tropical cyclone diana 1984 abstract a high resolution 3 km horizontal grid spacing near cloud resolving numerical simulation of the formation of hurricane diana 1984 is used to examine the contribution of deep convective processes to tropical cyclone formation this study is focused on the 3 km horizontal grid spacing simulation because this simulation was previously found to furnish an accurate forecast of the later stages of the observed storm life cycle the numerical simulation reveals the presence of vortical hot towers or cores of deep cumulonimbus convection possessing strong vertical vorticity that arise from buoyancy induced stretching of local absolute vertical vorticity in a vorticity rich prehurricane environment at near cloud resolving scales these vortical hot towers are the preferred mode of convection they are demonstrated to be the most important influence to the formation of the tropical storm via a two stage evolutionary process i preconditioning of the local environment via diabatic production of mul

new radiocarbon chronology for the guerrero member of the lujan formation buenos aires argentina palaeoclimatic significance abstract new radiocarbon dating performed on materials from the guerrero member of the lujan formation considerably enlarges the time period previously assigned to this unit new data suggest that deposition began about the last glacial maximum ca 21 ka bp and continued until at least ca 10 ka bp during this period several climatic and biological events occurred among the latter the last processes leading to the extinction of pleistocene megafauna

source apportionment of elevated pah concentrations in sediments near deep marine outfalls in esquimalt and victoria bc canada is coal from an 1891 shipwreck the source abstract previous studies have suggested that coal from the 1891 shipwreck of a collier off victoria bc canada is responsible for elevated parent unsubstituted pah concentrations in sediments near deep marine outfalls from esquimalt and victoria in the strait of juan de fuca to resolve this question we analysed a comprehensive suite of resolved and unresolved complex mixture ucm alkanes tricyclic terpane hopane and sterane biomarkers and parent and alkyl polycyclic aromatic hydrocarbons pahs in samples of coal wastewater and sediments composition patterns principal components analysis pca models and pah and biomarker ratios all indicate that coal from the collier does not make a dominant contribution to any sediment sample mass balance calculations based on the n c 24 content and 24 4 tetracyclic terpane to 26 3r tricyclic terpane ratio in coal provide a particularly good match between predicted and observed alkyl pah concentrations for sediments with high alkyl naphthalenes and phenanthrene anthracenes and low ucm but the predicted coal contribution substantially underestimates the measured parent pahs for all sediment samples methylbenz a anthracene chrysene profiles for sediments with a dominance of parent pahs are very close to coal tar with a marked predominance of methylbenz a anthracenes and the possible 10 methylbenz a anthracene as a major constituent while the methylchrysenes predominate in coal hence coal from the collier could account for most alkyl pahs in the sediments but dredged sediment containing pyrolised coal waste from a former coal gas plant in victoria harbour is a more likely source for the samples with elevated parent pahs pah ratios indicate that these sources are superimposed on combustion pahs introduced by a combination of atmospheric deposition and delivery via stormwater and the outfalls parent pah distributions also suggest that pahs in wastewater that originate from oils and soot in liquid fossil fuel combustion are dispersed and degraded while the larger wood char particles containing pahs more protected from degradation settle closer to the outfalls overall results suggest that pahs have predominant sources in wood combustion coal and possibly coke with a likelihood of much lower bioavailability than would be expected from wastewater dominated by oils and soot from vehicle combustion

petroleum generation an easy and widespread process in hydrothermal systems an overview abstract the conversion of organic matter to petroleum products by hydrothermal activity is an easy process occurring in nature in many types of environments geologically immature organic matter of marine sediments has been shown to be altered to petroleum products by this process in the guaymas basin escanaba trough bransfield strait and atlantis ii deep and this process probably occurs elsewhere in active sedimented rift systems contemporary organic detritus and or viable microorganisms are also converted in part to petroleum like products when they become entrained by turbulent mixing into hydrothermal vent waters resulting in their instantaneous hydrous pyrolysis this latter case occurs in hydrothermal vent fields without a sedimentary cover emanating directly from oceanic ridges as for example on the east pacific rise at 13 n and 21 n and on the mid atlantic ridge at 26 n this process is probably also ubiquitous for all actively venting sediment starved oceanic ridges the hydrocarbon products generated in these areas have been compared in terms of composition organic matter sources and analogy to reservoir petroleum they represent a major carbon source for chemosynthetic assimilation by vent biota and are compositionally similar to normal petroleum

biomarker signatures of the iconic glossopteris plant abstract glossopteris is the quintessential marker plant that dominated the forests of the southern hemisphere continents during the permian before their abrupt extinction at the close of the palaeozoic fossilized leaf and stem remains of glossopteris plants collected from the permian succession of eastern india were analysed to recognize the molecular signatures of solvent extractable and non extractable organic matter lipid derived aliphatic and aromatic biomarkers were studied using gc ms and gc gc tofms while tetramethylammonium hydroxide tmah thermochemolysis with gc ms and gc gc tofms was used to reveal lignin precursors the thermal maturity indices indicate low thermal rank for both samples the presence of aromatic diterpanes in the leaf extract suggests that the glossopteris plant was able to biosynthesize abietic acid and related plant terpenoids the thermochemolysis products thermochemolysates of the samples contain monomethoxy and dimethoxybenzene derivatives produced from p hydroxyphenyl and guaiacyl units of lignin respectively which are the main constituents of extant gymnosperm lignin the thermochemolysates indicate that lignin biosynthesis had evolved in glossopteris

experiments in waterlogging and sedimentology of charcoal results and implications abstract fossil charcoal has a sporadic occurrence in sedimentary rocks since devonian time it is moderately common as a component of the organic material found in a wide variety of facies but there are also some notable concentrations which occur locally these occurrences have considerable palaeobotanical and palaeoecological value because the process of charring may result in excellent preservation of plant tissue if assemblages of charred material are to be used to interpret palaeoenvironments it is important to understand the behaviour of charcoal during transport from the site of the fire charcoal is an unusual sedimentary material because most fresh material floats but with prolonged immersion becomes waterlogged and sinks we carried out a series of waterlogging experiments on uncharred material and charcoal from a range of different plant types and tissues these show considerable variations in the rates of waterlogging of different charred and uncharred plant tissues and it is suggested that buoyancy contrasts are likely to result in separation during transport and deposition furthermore experiments in a flume tank have shown that the process of deposition of charcoal in sand is controlled by the rate of migration of bedforms which is in turn determined by depth flow velocity and sediment supply allochthonous assemblages of charred and uncharred plant debris will most probably be biased and not fully representative of the contemporaneous plants or vegetation the presence of charcoal concentrations may be used as an aid in interpreting palaeohydraulic conditions

alkane and pah depositional history sources and fluxes in sediments from the fraser river basin and strait of georgia canada hydrocarbon data for dated sediment cores from fraser basin lakes and the strait of georgia in canada reveal a pristine pre industrial background that remains unaltered in modern sediments far from human activities these pristine sediments contain polycyclic aromatic hydrocarbons pahs from combustion natural forest and prairie fires and alkanes and pahs from weathering of soils containing vascular plant remains and natural petroleum hydrocarbons and algal production at other locations examined however these natural loadings have been augmented over the past century by hydrocarbons from petroleum the combustion of liquid oil gasoline and solid coal wood fuels and from processing of wood either directly from disturbed land and slash burning or indirectly through pulp mill effluent although contamination is clearest where there are nearby human activities alkane profiles pah distributions and alkane unresolved complex mixtures suggest a widespread contamination from petroleum combustion products from human activities can also be identified although with less source specificity than with the petroleum products regional emissions from anthropogenic combustion processes appear to support modern pah increases within the fraser river basin and there is little evidence of inputs from global emissions principal components analysis using the new centred log ratio normalisation procedure to normalise data discriminates well between pahs entering lakes from runoff or the atmosphere and pah formed diagenetically within lake sediments as well as between combustion and petroleum pahs

identification and distribution of chrysene methylchrysenes and their isomers in crude oils and rock extracts abstract chrysene its methylated homologues and their structural isomers are important polyaromatic compounds in crudes oils coals and sediment extracts chrysene benzo a anthracene methylchrysenes and methylbenzo a anthracenes were unequivocally identified in mass chromatograms by comparison with authentic standards and by retention indices reported in the literature the response factors relating those of chrysene and methylchrysenes to internal standards perdeuterated chrysene chrysene d12 and pyrene pyrene d10 were obtained by gc ms analyses of mixture solutions with different concentration ratios the oil families of ordovician reservoirs in the cratonic region of the tarim basin nw china are distinguished by the distribution patterns of chrysene methylchrysenes and their isomers the majority of the oil accumulations and sediment extracts from the middle upper ordovician source rocks are characterized by low concentrations of benzo a anthracene and methylbenzo a anthracenes relative to chrysene and methylchrysenes respectively in contrast some oils with relatively high abundances of benzo a anthracene and methylbenzo a anthracenes were derived from cambrian and lower ordovician source rocks the effect of maturity on the distribution patterns of methylchrysenes in tertiary lacustrine shales from the liaohe basin east china was investigated the 2 1 methylchrysene ratio keeps a nearly constant value with increasing maturity at the low maturity stages and then it abruptly increases corresponding approximately to the onset of intense c 15 hydrocarbon generation this indicates that chrysene and its methylated homologues are useful molecular indicators in petroleum geochemistry

fire prone plant communities and palaeoclimate of a late cretaceous fluvial to estuarine environment pecinov quarry czech republic the botanical identity and facies distribution of fossil charcoal is described from middle to late cenomanian 90 94 ma fluvial to estuarine units at pecinov quarry near prague czech republic braided alluvial facies associations contain charred conifer woods family pinaceae possibly derived from upland forest fires and abundant charred angiosperm woods flowers and inflorescences families lauraceae and platanaceae derived from riparian gallery forest fires unit 2 retrogradational coastal salt marsh facies associations contain abundant charred conifer wood families cheirolepidiaceae and cupressaceae taxodiaceae derived from fires in halophytic backswamp forest and rare pinaceous charred cones and lauraceous angiosperm wood washed downstream from fires further inland units 3 4 progradational coastal facies associations within an estuary mouth setting contain abundant charred conifer wood family cupressaceae taxodiaceae common taxodiaceous conifer and angiosperm leaves fern rachises and lycopsid stems derived from fires in mesic backswamp taxodiaceous forests and supra tidal fern lycopsid thickets unit 5 growth rings in angiosperm and conifer woods leaf physiognomy and computer models indicate that climate was equable warm and humid but that there was a short annual dry season most fires probably occurred during these annual drought periods the abundance of charcoal and the diversity of taxa preserved in this state indicate that nearly all plant communities were fire prone physiognomically the pecinov flora resembles present day seasonally dry subtropical forests where fires are a common occurrence

tropical cyclone convection the effects of ambient vertical vorticity we present idealized numerical model experiments to isolate and quantify the influence of ambient vertical vorticity on the dynamics of deep convection such as that in the inner core region of a tropical depression the vertical vorticity is represented either by a uniform horizontal shear a uniform solid body rotation or a combination of both we show that the growing convective cells amplify locally the ambient rotation at low levels by more than an order of magnitude and that this vorticity which is produced by the stretching of existing ambient vorticity persists long after the initial updraught has decayed significant amplification of vorticity occurs even for a background rotation rate typical of the undisturbed tropical atmosphere and even for clouds of only moderate vertical extent this finding has important implications for tropical cyclogenesis and provides a basis for a unified theory of tropical cyclogenesis and tropical cyclone intensification the presence of ambient vertical vorticityreduces the updraught strength slightly more when the vorticity is associated with horizontal shear than when it is associated with solid body rotation on account of enhanced entrainment the reduction of the updraught strength can be attributed to the reduction of the lateral inflow by the centrifugal and coriolis forces despite the significant amplification of vorticity the sum of the centrifugal and coriolis forces is mostly small compared with the lateral pressure gradient thus at the level of background rotation studied the rossby elasticity effects in the updraught postulated by montgomery et al are not large but may be important for higher levels of background rotation the simulations ignore several processes that are likely to be important in reality such as ambient vertical shear and surface friction but they provide important benchmark calculations for interpreting the additional complexity arising from the inclusion of these effects copyright c 2011 royal meteorological society

polycyclic aromatic hydrocarbons in ancient sediments and their relationships to palaeoclimate combustion derived and land plant derived polycyclic aromatic hydrocarbons pahs have been investigated for an upper triassic to middle jurassic sedimentary sequence from the northern carnarvon basin western australia the former included fluoranthene pyrene benzofluoranthenes benzo e pyrene and benzo a pyrene and the latter included retene cadalene and simonellite combustion derived pahs are most abundant in the upper triassic and late lower jurassic sediments the abundances of land plant derived markers all maximise in the upper part of the lower jurassic section but vary independently of one another through time the changes in the relative abundances of these markers have been related to the variation of regional climatic conditions especially the changes in humidity and seasonality during the late triassic to middle jurassic times

charcoal recognition taphonomy and uses in palaeoenvironmental analysis abstract charcoal predominantly the product of wildfires is abundant in many sedimentary rocks deposited in a wide range of environments from terrestrial to marine it also occurs in some volcanic rocks this paper outlines aspects of charcoal formation both natural and experimental and briefly considers the taphonomic processes leading to a final assemblage this is done using examples from recent fires and through experimentation the ways in which charcoal assemblages are recognized in the field and extraction in the laboratory are also considered methods of charcoal identification are presented the range of charcoalified plant organs that can be found is discussed and a wide range of study methods outlined including light microscopy dark field light microscopy reflectance microscopy scanning electron microscopy and synchrotron radiation x ray tomographic microscopy emphasis in this paper is on the study of macro and meso charcoal above180 m finally there is a consideration of the broad use of charcoal from plant evolution studies fire history studies vegetation studies anatomical studies climate and atmospheric studies and the wider importance of charcoal for the earth and biological sciences charcoal is information rich but yet is an under utilized resource

pah refractory index as a source discriminant of hydrocarbon input from crude oil and coal in prince william sound alaska geochemical correlation and differentiation of hydrocarbons from crude oils and coals is difficult the complex mixture of the hydrocarbon constituents and the dynamic nature of these constituents in the environment as they weather contribute to this difficulty a new parameter the polycyclic aromatic hydrocarbon pah refractory index is defined here to help in this correlation the pah refractory index is a ratio of two of the most refractory constituents of most crude oils namely triaromatic steranes and monomethylchrysenes these are among the most persistent compounds in oil after deposition in the environment and thus retain reliably the signature of the original petroleum input this index is utilized in prince william sound pws to differentiate three different oils as well as to provide evidence that coal not oil is the dominant source of the pahs which are prominent constituents of marine sediments from pws and the gulf of alaska

organic geochemistry of late jurassic paleosols dirt beds of dorset uk abstract paleosols from the lower part of the purbeck limestone group which crops out extensively in dorset southern england are shown to contain type iv kerogens comparisons with mesozoic organic materials suggest that some of the paleosol kerogen is composed of fossil charcoal the charcoal would have been produced by wildfires in the undergrowth of purbeck gymnosperm forests contrasting the paleosol charcoal with laboratory produced counterparts suggest that originally significant amounts of functionalised organic matter should have persisted secondary oxidation and decay processes therefore must have removed all but the most resistant aromatic units in the charcoal the importance of post fire processes implies a strong influence on preservation from oxygen supply water washing and host sediment type these factors may have been related to pedogenesis relative sea level and local fault movement in the late jurassic

notes on the origin of inertinite macerals in coals observations on the importance of fungi in the origin of macrinite macrinite is a generally rare inertinite maceral often incorporating remnants and fragments of other macerals including vitrinite liptinite and other inertinite the associated inertinites include multiple forms of funginite funginite is also commonly found in association with vitrinite of slightly elevated reflectance and with degraded varieties of vitrinite together with the highly degraded macrinite the latter two associations are here inferred to be part of a continuum of fungal and microbial degradation of peat in any case the origin of some macrinite is potentially distinct from that of inertinite generated by fire

alkane and pah biomarkers as tracers of terrigenous organic carbon in arctic ocean sediments abstract we present the first sedimentary biomarker study encompassing the entire arctic ocean a large data set of organic markers for terrigenous petroleum and combustion inputs alkanes hopanes and steranes parent and alkyl polycyclic aromatic hydrocarbons pahs is examined for patterns in space and time using principal components analysis pca and partial least squares pls biomarker patterns reveal the central arctic ocean basin sediments to be compositionally distinct from those of the mackenzie river beaufort sea and barents sea but similar to those of the laptev sea pah distributions reflected in pah ratios and pca projections demonstrate that arctic ocean sediment is dominated by natural inputs to the extent that anthropogenic combustion pahs are not significant we find only modest changes between the glacial and post glacial sediments for atmospherically transported hydrocarbon biomarkers while particle associated biomarkers were captured strongly at basin edges during the glacial period and much more evenly transported across basins during the post glacial period the orders of magnitude decreases in particle associated petrogenic alkanes and pahs in central basins during glacial times coupled with the uniformity of most petrogenic biomarker parameters for most basin and shelf locations reflect a massive reduction in ice transport that makes the margins the most likely source of petrogenic material for the pleistocene holocene central arctic basins the proximity of large coal deposits of various maturity levels along the lena river the overlap in pah and biomarker composition of the laptev sea and surficial sediments from the central arctic ocean and the location of the laptev sea at the origin of the main transpolar drift all point to eroded coals from the lena river laptev sea as the likely source of petrogenic hydrocarbons to the central arctic ocean the ubiquitous presence of allochthonous coal in arctic ocean surface sediments provides a major constraint on the use of petrogenic biomarkers to infer the presence of subsurface petroleum reserves

geochemistry of a thermally immature eagle ford group drill core in central texas abstract the upper cretaceous eagle ford group displays significant lateral and vertical geochemical variability much of the work on the eagle ford group has been focused southwest of the san marcos arch to more fully characterize the eagle ford across the entire region a thermally immature drill core was acquired north of the san marcos arch that recovered the pepper shale and the eagle ford group molecular and isotopic analyses of rock extracts were combined with bulk organic and inorganic geochemistry and mineralogy to track the variability in organic matter source and depositional environment as well as to identify drivers of organic enrichment the pepper shale received significant terrigenous organic matter in its distal deltaic or prodeltaic setting compared to the more distally deposited eagle ford group that primarily hosts marine organic matter the upper eagle ford contains two chemofacies the older upper eagle ford chemofacies has similar mineralogy and organic matter to the underlying lower eagle ford and both intervals display good to excellent source rock potential in contrast the younger upper eagle ford chemofacies has a different sterane assemblage a larger terrigenous component and a higher clay mineral abundance however anoxic to euxinic depositional conditions distinguish the lower eagle ford from the upper eagle ford which was deposited under oxic to dysoxic conditions redox chemistry and organic matter source are two important variables that determine source rock quality but they did not change in parallel during eagle ford deposition differences in organic facies explain the tmax variability and depositional redox conditions governed organic richness in the eagle ford group in central texas

reworked triterpenoid and steroid hydrocarbons in a recent sediment abstract the distributions of steranes pentacyclic triterpanes and aromatic steroid hydrocarbons in core sections of a recent intertidal sediment bridgwater bay severn estuary u k have been examined by gas chromatography mass spectrometry depending on sample depth the distributions are explicable in terms of 1 i a reworked origin for these compounds from a geological source probably as a result of erosion of nearby organic rich sediments of lower liassic age or 2 ii a dual origin from both i and a more mature source probably an anthropogenic input of petroleum origin these results show that not all of these steroid and triterpenoid hydrocarbons in surface sediments necessarily result from fossil fuel pollution they indicate also that attention should be paid to the possibility of contributions from reworked components when using the distributions of these compounds in geochemical studies of sediments that are low in extractable organic matter

tropical cyclone convection the effects of a vortex boundary layer wind profile on deep convection we describe idealized numerical model experiments to study the effects of a vortex boundary layer wind profile on the generation of vertical vorticity in tropical deep convection situations are considered in which there is either no vertical shear above the boundary layer or negative vertical shear appropriate to a warm cored vortex deep convection growing in these environments develops dipole structures of vertical vorticity in which the cyclonic gyre is favoured and persists longer than the anticyclonic one the orientation of the dipole at a particular height is determined partly by that of the ambient horizontal vortex lines which rotate with height and also by the vertical advection of vertical vorticity from below an increase in the magnitude of boundary layer shear enhances the distortion of the initial thermal weakening its subsequent ascent rate this effect is detrimental to vertical vorticity production by stretching but because the increase in shear implies an increase in the magnitude of horizontal vorticity that can be tilted its net effect on the vertical vorticity production by tilting cannot be foreseen in the calculations described the effect of the increased horizontal vorticity dominates so that updraughts rising in stronger vertical shear have larger vertical vorticity maxima despite smaller vertical velocity maxima with negative vertical shear above the boundary layer the vorticity dipole reverses in sign with height as in a recent study of the effects of unidirectional shear the results provide a basis for appraising a recently proposed conceptual model for the inward contraction of eyewall convection in tropical cyclones as well as a starting point for developing an improved understanding of the formation of a vorticity monopole during tropical cyclogenesis

climatic vs tectonic controls on peat accretion in non marine setting an example from the žacleř formation yeadonian bolsovian in the intra sudetic basin czech republic abstract the acle coalfield in the western part of the intra sudetic basin is an example of coal accumulation in an alluvial valley deposited under a long term 3 m y stable tectonic regime with climatic oscillations possibly operating on several time scales the resulting sedimentary record about 600 m thick encompasses about 60 coal bearing cycles formed in a relatively small and localized part of the valley whereas elsewhere a higher clastic input and or lower rate of subsidence resulted in deposition of strata with very little coal available data suggest that tectonics produced accommodation for sediments and via changes in topography and or size of the source area affected the volume and dispersal patterns of clastic material transported to the depocentre areas with long term tectonic stability were suitable places for recognition of climatic signals in the sedimentary record modified by the intensity of local clastic input climatic fluctuations generated coal bearing cycles probably through a variable intensity of precipitation which affected the density of vegetation cover across the landscape along with evaporation and groundwater table these factors influenced the intensity of chemical weathering and hence regulated the volume and composition of clastics delivered to the depocentre this in turn resulted in alternation of short periods of bedload dominated deposition during the seasonally dry part of the cycle with periods of dominantly suspended load and organic peat deposition during the more humid everwet part of the cycle estimated duration of the basic cycles 46 k y approximates the orbitally driven axial tilt cyclicity basic cycles are arranged into two larger scale cyclic patterns lasting for 270 k y and 1 5 m y respectively which broadly correspond with the timing of glacial maxima and minima inferred from high latitude glacial deposits of gondwanan basins all the coals of the acle coalfield display similar petrographic composition dominated by collotelinite and field observations as well as detailed petrographic study show that they formed in planar rheotrophic peat swamps where long lasting peat accretion was episodically interrupted only by major floods on a century to millennial scale

esr dating of pleistocene mammal teeth and its implications for the biostratigraphy and geological evolution of the coastal plain rio grande do sul southern brazil abstract the fossiliferous deposits in the coastal plain of the rio grande do sul state southern brazil have been known since the late xix century however the biostratigraphic and chronostratigraphic context is still poorly understood the present work describes the results of electron spin resonance esr dating in eleven fossil teeth of three extinct taxa toxodon platensis stegomastodon waringi and hippidion principale collected along chui creek and nearshore continental shelf in an attempt to assess more accurately the ages of the fossils and its deposits this method is based upon the analysis of paramagnetic defects found in biominerals produced by ionizing radiation emitted by radioactive elements present in the surrounding sediment and by cosmic rays three fossils from chui creek collected from the same stratigraphic horizon exhibit ages between 42 3 ka and 34 7 ka using the combination uptake model for radioisotopes uptake while a incisor of toxodon platensis collected from a stratigraphic level below is much older fossils from the shelf have ages ranging from 7 1 10 5 ka to 18 3 ka indicating the mixing of fossils of different epochs the origin of the submarine fossiliferous deposits seems to be the result of multiple reworking and redeposition cycles by sea level changes caused by the glacial interglacial cycles during the quaternary the ages indicate that the fossiliferous outcrops at chui creek are much younger than previously thought and that the fossiliferous deposits from the continental shelf encompass ensenadan to late lujanian ages middle to late pleistocene

molecular tracers preserved in lower jurassic blanowice brown coals from southern poland at the onset of coalification organic geochemical and petrological characteristics abstract the petrographic and molecular characteristics of the pliensbachian toarcian blanowice brown coals and associated sediments are described these coals are generally dominated by vitrain macerals although in one sample the inertinite is 60 this is interpreted as a result of wildfire or peat fire activity which was confirmed by the co occurrence of charcoal fragments and elevated relative concentrations of unsubstituted pahs in the samples vitrinite reflectance values are in the range of 0 49 0 56 ro and the c content varies from 30 3 61 9 placing the coals within the sub bituminous coal group however detailed characterization of coal extracts revealed their highly immature character based on the occurrence of phenolic abietanes such as ferruginol sugiol and 7 oxototarol as well as other biomolecules including labdanoic acid cholesterol and sitosterol this is one of the first descriptions of natural product compounds in jurassic sedimentary rocks moreover in addition to typical lignin decomposition products dicarboxylic acids with a preponderance of succinic acid were identified to the best of our knowledge free dicarboxylic acids have not been reported previously from coal extracts these acids are characteristic resin constituents we speculate that a low ca 40 50 c but long term temperature influence led to an increased vitrinite reflectance values ca 0 55 ro with only minor changes to the composition of unstable biomarkers and biomolecules moreover the resin matrix could protect unstable compounds against geochemical structural alteration vitrinite reflectance values may also be elevated due to oxidation which caused paler in colour reaction rims the presence of phenolic abietanes and the absence of abietic and dehydroabietic acids suggest that the cupressaceae and or podocarpaceae families were the most likely peat forming plant species

the effects of igneous dike intrusion on organic geochemistry of black shale and its implications late jurassic jhuran formation india abstract this study documents the effects of igneous dike intrusion on organic geochemical parameters of a shallow marine originated late jurassic black shale av toc 2 2 wt in the kutch rift basin in western india the dike intrusion forms extremely to mildly altered meter scale zones around them the primary wrinkled micro texture of the shale is lost completely and organic matter is charcoalized in the extremely altered zone recording a rock eval tmax 458 c immature type iii kerogen dominating the unaltered shale records abundant coniferal biomarkers such as retene ent beyerane phyllocladane ent kaurane abietane labdane and norisopimarane besides n alkanes hopanes and steranes the transition from the unaltered rock eval tmax

polycyclic aromatic hydrocarbons pahs in late eocene to early pleistocene mudstones of the sylhet succession ne bengal basin bangladesh implications for source and paleoclimate conditions during himalayan uplift abstract distribution and possible sources of polycyclic aromatic hydrocarbons pahs have been investigated in 23 late eocene to early pleistocene mudstones from the sylhet succession of the northeastern bengal basin bangladesh paleoclimatic conditions in the southern himalaya region throughout the himalayan uplift were reconstructed based on combustion derived pahs and aromatic land plant derived biomarkers phenanthrene fluoranthene fla pyrene py benz a anthracene baan chrysene triphenylene chry tpn benzofluoranthenes bflas benzo e pyrene bepy benzo a pyrene bapy perylene pery indeno 1 2 3 cd pyrene inpy benzo ghi perylene bghip coronene cor and retene ret were the identified pahs fla fla py ratios 0 5 and inpy inpy bghip 0 2 from almost all sylhet samples suggest occurrence of natural wildfires low contents of baan and bapy indicate decomposition by long exposure to sunlight before sedimentation or early diagenetic weathering increased cor inpy and bghip contents suggest occurrence of larger high temperature wildfires correlation coefficients of the pahs and p values for statistical hypothesis testing showed that the positive and negative correlations within the pahs may be indicative of high or low temperatures in wildfires fungi derived pery showed negative correlations with py r 0 67 p 4 6 10 4 and fla r 0 56 p 5 0 10 3 but not with cor bflas inpy and bghip based on the correlation coefficients for all pahs and their p values five statistical groups py fla cor bflas inpy bghip baan chry tpn bapy pery and ret were recognized these groups are probably correlated with origins and depositional processes according to the results the sylhet succession was deposited in three differing paleoclimatic regimes 1 first phase late eocene to early miocene early to middle stage of himalayan uplift high contents of combustion derived pahs fla py and bepy significant gymnosperm derived ret and low pery abundances in the jaintia and barail groups indicate arid climatic conditions although wildfires could often occur 5 or 6 ring combustion pahs cor inpy and bghip contents are low suggesting that the wildfires were relatively low temperature 2 second phase middle to late miocene middle to late stage of himalayan uplift combustion derived pahs and fungi derived pery were dominant in the surma group the climate was arid to humid and seasonal with a dry season giving conditions suitable for combustion abundant fla bflas bepy cor inpy and bghip imply high temperatures in large wildfires however frequency of the wildfires decreased because of wet climate 3 third phase late miocene to pleistocene late stage of himalayan uplift moderate to high pery contents and low fla py and bepy abundances in the tipam and dupitila groups indicate establishment of more humid climate inpy bghip cor bflas and bapy were predominant intensified humid and seasonal climate arising from the himalayan monsoon decreased the incidence and frequency of general wildfires but increased the ratio of large to small wildfires

sources and distribution of hydrocarbons in bridgwater bay severn estuary u k intertidal surface sediments abstract hydrocarbon distributions in two intertidal surface sediments from bridgwater bay were examined by high performance liquid chromatography hplc gas chromatography gc and gas chromatography mass spectrometry gc ms to investigate distributions and sources of hydrocarbons two major hydrocarbon sources were identified pyrogenic polycyclic aromatic hydrocarbons pahs and a chronic petrogenic input other probable sources were algal higher plant and ddt related pesticides it was not possible to detect a contribution to the surface sediments from a nearby liassic shale petrogenic biomarker distributions were broadly similar in the sediment samples possibly reflecting a degree of resuspension and mixing of sediments within bridgwater bay however the significance of some slight differences in steroidal hydrocarbon distributions could not be determined a relatively greater contribution from the petrogenic source s than from the pyrogenic source was noted in the finer grained sediment sample an extended range of pahs was noted in both sediment samples with molecular weights of up to 326 detected a group of compounds comprising terphenyls cyclohexylbiphenyls and dicyclohexylbenzenes was detected which appeared to have a petrogenic origin

revisiting wildfires at the k pg boundary 1 the discovery of large amounts of soot in clays deposited at the cretaceous paleogene k pg boundary and linked to the 65 ma chicxulub impact crater led to the hypothesis that major wildfires were a consequence of the asteroid impact subsequently several lines of evidence including the lack of charcoal in north american sites were used to argue against global wildfires close to the impact site fires are likely to be directly ignited by the impact fireball whereas globally they could be ignited by radiation from the reentry of hypervelocity ejecta to date models of the latter have yet to take into account that ejection and thus the emission of thermal radiation is asymmetric and dependent on impact angle here we model 1 the impact and ejection of material 2 the ballistic continuation of ejecta around a spherical earth and 3 the thermal pulse delivered to the earth s surface when ejecta reenters the atmosphere we find that thermal pulses in the downrange direction are sufficient to ignite flora several thousand kilometers from chicxulub whereas pulses at most sites in the uprange direction are too low to ignite even the most susceptible plant matter our analyses and models suggest some fires were ignited by the impact fireball and ejecta reentry but that the nonuniform distribution of thermal radiation across the surface of the earth is inconsistent with the ignition of fires globally as a direct and immediate result of the chicxulub impact instead we propose that the desiccation of flora by ejecta reentry as well as the effects of postimpact global cooling darkness left much of the terrestrial flora prone to fires and that the volume of soot in the global k pg layer is explained by a combination of syn and postimpact wildfires

convective contribution to the genesis of hurricane ophelia 2005 abstract the convection occurring in the tropical depression that became hurricane ophelia 2005 was investigated just prior to tropical storm formation doppler radar showed a deep wide intense convective cell of a type that has been previously thought to occur in intensifying tropical depressions but has not heretofore been documented in detail the updraft of the cell was 10 km wide 17 km deep had updrafts of 10 20 m s 1 throughout its mid to upper levels and contained a cyclonic vorticity maximum the massive convective updraft was maintained by strong positive buoyancy which was maximum at about the 10 km level probably aided by latent heat of freezing evaporative cooling and precipitation drag occurred in the rain shower of the cell but were insufficient to produce a strong downdraft or gust front outflow to force the updraft the convective updraft was fed by a layer of strong inflow that was several kilometers deep wind induced turbulence just above the ocean surface enriched the equi

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

igneous activity and organic maturation in the midland valley of scotland abstract the general relationship of erich stach s research work to the effects of igneous activity on organic maturation is briefly considered the geological history of the midland valley of scotland is then reviewed as a graben which developed in devonian old red sandstone times and continued to do so as lithospheric tensional stretching was maintained throughout the carboniferous a significant factor in relation to the development of organic maturation was the widespread igneous activity that persisted throughout much of upper palaeozoic times calc alkaline volcanic rocks are a major feature within the molasse type deposits of the old red sandstone after a period of quiescence in later old red sandstone times the continuing tensional stretching initiated or rejuvenated major crustal fractures extensive volcanic sill and dyke activity exercised an important influence on the predominantly shallow water deltaic deposits of the carboniferous alkaline olivine basalts were erupted in the early carboniferous while volcanic activity in the later carboniferous was essentially phreatic two major intrusive episodes occurred the first of alkaline sills in early to mid carboniferous times which were closely related to volcanic plugs and eruptive centres the second in post westphalian times when tholeiitic sills and dykes with no known relationships with any extrusive rocks were injected the effects of this igneous activity on organic maturation can be considered under four headings 1 1 although the general development of maturation of carboniferous organic matter which includes many coal seams and oil shales was controlled to some degree by burial history the regional pattern of igneous activity was also influential thus there is a gradual increase of coalification from east to west in the midland valley which corresponds with an increasing thickness of volcanic pile in the central and westerly parts of the graben suggesting that there may have been a greater regional heat sink in the west during the carboniferous the level of coalification is nowhere particularly high except where affected by intrusions and regional reflectance gradients generally vary between r oil vitrinite 0 2 km to 0 4 km without displaying any consistent pattern 2 2 the post westphalian tholeiitic quartz dolerite midland valley sill which underlies most of the central and eastern parts of the graben has produced extensive reflectance thermal aureoles in the organic matter above and below the intrusion the olivine dolerite and teschenite sills of namurian early westphalian times many of similar thickness to the quartz dolerite intrusions fail to produce significant reflectance thermal aureoles this major difference in organic matter response to the intrusions can only be explained in terms of the initial rank level of the organic matter differences in degree of compaction of the sediments and particularly in the amount of water the sediments contained at the time of intrusion 3 3 maturation of organic matter closely associated with extensive surtseyan type volcanic activity in the eastern part of the graben displays no relationship to the regionally developed coalification in associated sediments although some vitrinite clasts in the pyroclastic deposits have had their reflectances raised to meta anthracitic rank reflectance levels of clasts in tuffs and agglomerates are generally not much raised above the regional reflectance level suggesting incorporation of organic matter in ash streams in which water was an important cooling and protective component 4 4 the close relationship of organic matter of all kinds with volcanic and intrusive igneous rocks has led to a marked increase of parent polycyclic aromatic hydrocarbons pah in the aromatic fractions of organic extracts the source of these hydrocarbons is the combustion and or pyrolysis of organic matter caused by the high temperatures of the igneous materials whether volcanic or intrusive these pah may be directly generated or absorbed from the surrounding environment

molecular organic geochemistry of a proposed stratotype for the oxfordian kimmeridgian boundary isle of skye scotland the composition of the soluble organic matter of the oxfordian kimmeridgian flodigarry shale member isle of skye scotland is presented for the first time a continuous succession of silty clays and nodular limestone beds is exposed on a rocky shore to the north of staffin bay this succession is proposed as a potential stratotype of the boundary between the oxfordian and kimmeridgian stages this paper points out the exceptional preservation and very low thermal degradation of the organic matter indeed the molecular composition is characterized by the abundance of unsaturated biomarkers hopenes and diasterenes as well as undamaged bioterpenoids ferruginol and sugiol the abundance of long chain n alkanes characterized by an odd over even predominance reveals a dominant continental contribution this is also attested to by the relatively high amounts of plant biomarkers e g ferruginol sugiol cadalene and retene which suggest a palaeovegetation largely composed of pinophytes especially cupressaceae taxodiaceae and cheirolepidiaceae on the nearest emerged lands the water column of the depositional environment was oxic in its upper part and rather dysoxic in its lower part the composition of the organic matter does not significantly change along the flodigarry shale member in other words no evolutionary events or drastic change in palaeoenvironments can be deduced from the molecular content of these sedimentary rocks and it does not allow us to support a precise location for the oxfordian kimmeridgian boundary in the succession

the geology botany and chemistry of selected peat forming environments from temperate and tropical latitudes abstract peat has been studied in several geologic settings 1 glaciated terrain in cold temperate maine and minnesota u s a 2 an island in the atlantic ocean off the coast of maine where sea level is rising 3 the warm temperate u s atlantic and gulf coastal plains where sea level has changed often and 4 the tropical coast of sarawak malaysia and the tropical delta of the batang hari river sumatra indonesia most of these deposits are domed ombrotrophic or partly ombrotrophic bogs in which peat accumulation continued above the surface of the surrounding soil however the bogs of the u s atlantic and gulf coastal plains are comparatively not as domed and many have almost level surfaces in some bogs aquatic or semi aquatic plant materials accumulated replaced water in the depressions and formed a surface on which marsh or swamp vegetation could subsequently live die and accumulate in others the plant materials accumulated initially on level silt or sand surfaces supporting marshes or swamps as the peat dome formed plants growing on it changed from luxuriant ones near the base of the dome where nutrients were brought into the bog by surface and ground water to stunted ones at the top of the dome where the raised bogs are fed by nutrient poor precipitation the physical and chemical changes that take place in the sequence of environments from the pond stage of deposit development through the grassy marsh stage through the forested swamp stage and finally through the heath dome stage can be measured in terms of acidity and ash volatile matter carbon hydrogen nitrogen sulfur and oxygen contents as well as in the kind and distribution of trace elements the organic and inorganic contents of the deposits relate to geomorphology and geomorphology relates to their settings as models of coal formation some domed peat deposits may help in solving problems of distribution and character of ancient coal beds but clearly not all peat deposits are precursors of coal most holocene peat deposits are subject to destruction by erosion fire and decomposition through microbial and chemical oxidation before burial the best environments for coal precursors have biomass accumulation a continuously rising water table within the mass and minimum influx of clay and silt until preservation by burial the most suitable settings for future economic coal deposits are domed bogs that accumulate thick widespread peat having low ash and low sulfur contents the ombrotrophic peat deposits of tropical sarawak and sumatra are thick and extensive contain low ash and low sulfur peat and have high heating values they are considered to be the best tropical coal analogs because of their extent and chances of preservation the base of the peat is below adjacent river levels and chemical and structural conditions are favorable for accumulation

organic geochemical and paleoenvironmental characterization of the brown shale formation kiliran sub basin central sumatra basin indonesia abstract the central sumatra basin csb formed during the late eocene to early oligocene is the most prolific hydrocarbon basin in indonesia the brown shale formation of the pematang group is the sole known source rock for the tens of billions of barrels of oil located in the csb samples analyzed in this study were from the karbindo coal mine in the kiliran graben of the kiliran sub basin located on the western side of the csb this study incorporates advanced organic geochemical and petrographical data of samples from the brown shale formation as well as interpretations from previous studies at this location to construct a detailed paleoenvironment model for this tertiary lake the lacustrine source rock was deposited under fresh water conditions with subtle changes in the environment that resulted in significant changes in ecologies based on new data from organic petrography biomarkers microscale sealed vessel pyrolysis and characterization of the polyaromatic hydrocarbons the organic matter in the brown shale formation was determined to be sourced primarily from lacustrine organisms with a small amount of terrestrial plant input 4 methylsterane concentrations and n alkane distributions indicate that non marine dinoflagellates and botryococcus braunii a race were likely a significant portion of the local biosphere

fossil charcoal as an indicator of palaeoatmospheric oxygen level charcoal results from incomplete combustion of plant material it is produced naturally by wildfire and being relatively tough and unbiodegradable it may be transported and incorporated into a variety of sedimentary environments wildfire requires adequate atmospheric oxygen for the combustion of plant fuel wood leaf litter fossil charcoal from the devonian onwards suggests that the oxygen level in the atmosphere has not fallen below 13 in this interval further the extreme flammability of even wet plant fuel at oxygen levels above 35 makes this the highest figure compatible with the occurrence of terrestrial vegetation

chemical characterization of lower devonian vascular plants vegetative remains of three coalified lower devonian vascular plants zosterophyllum psilophyton renalia were analyzed using flash pyrolysis gas chromatography mass spectrometry the distributions of pyrolysis products are compared with those from younger vascular plant fossil xylem cordaixylon callixylon and cuticle pachypteris the likelihood of the chemical preservation of characteristic higher plant macromolecules e g lignin and cutan in the lower devonian plant fossils is considered in light of this comparison and associated thermal maturity assessments reflectance values from vitrinite like macerals which may not be vitrinite sensu stricto in the lower devonian host rocks for the fossils selected for this study are shown to provide a reasonable assessment of the thermal maturity of these early vascular plant fossils although lignin altered through burial maturation is the most likely source of the prominent alkylphenols and aromatic hydrocarbons in the lower devonian tracheophyte flash pyrolysates a contribution from thermally modified tannins cannot be ruled out comparison of the highly aliphatic pyrolysates from the zosterophyllum and psilophyton axes with that of a thermally mature fossil gymnosperm leaf revealed that cutan was an important component in the devonian plant remains this is the earliest chemical evidence for the presence of cutan in vascular plants

a vortical hot tower route to tropical cyclogenesis abstract a nonhydrostatic cloud model is used to examine the thermomechanics of tropical cyclogenesis under realistic meteorological conditions observations motivate the focus on the problem of how a midtropospheric cyclonic vortex a frequent by product of mesoscale convective systems during summertime conditions over tropical oceans may be transformed into a surface concentrated warm core tropical depression as a first step the vortex transformation is studied in the absence of vertical wind shear or zonal flow within the cyclonic vorticity rich environment of the mesoscale convective vortex mcv embryo the simulations demonstrate that small scale cumulonimbus towers possessing intense cyclonic vorticity in their cores vortical hot towers vhts emerge as the preferred coherent structures the vhts acquire their vertical vorticity through a combination of tilting of mcv horizontal vorticity and stretching of mcv and vht generated vertical vorticity horizontally localized and exhibiting conve

organic matter from the callovian middle jurassic deposits of lithuania compositions sources and depositional environments abstract this study presents the first organic geochemical and petrographical investigation of the callovian deposits of the eastern part of the central european basin it is shown that in both the terrigenous papil formation lower callovian and shallow to deeper marine facies of the papartin and skinija formations middle and upper callovian respectively terrestrial organic matter predominates this is reflected by the carbon preference index values higher than 1 2 for all samples and in some cases higher than 2 as well as the occurrence of characteristic higher plant biomarkers like cadalene dehydroabietane simonellite and retene moreover in the case of the papil formation sugiol a natural product terpenoid produced by distinct conifer families has been detected in clay sediments the occurrence of such a biomolecule in the middle jurassic clays is reported for the first time its occurrence is probably connected with the presence of small wood debris in the clay sediments in samples of the papil formation charcoal fragments co occurring with unsubstituted polycyclic aromatic hydrocarbons were detected indicating that wildfires took place during the early callovian of lithuania and or neighbouring areas in the middle and upper marine callovian sediments of lithuania there is no evidence of anoxic conditions occurring in the water column however periodic anoxic or strongly dysoxic episodes may have occurred most probably below the photic zone during the deepest phase of the late callovian transgression as is evidenced from pyrite framboid diameter distribution and general impoverishment of benthic fauna huminite reflectance r r values for the investigated area are in the range of 0 21 0 31 suggesting the occurrence of immature organic matter such values indicate that these investigated deposits were close to the surface during their whole diagenetic history and the thickness of younger cover did not exceed ca 500 m this is also supported by a biomarker analysis in which less thermally stable hopanes and hopenes significantly dominated

moist multi scale models for the hurricane embryo determining the finite amplitude preconditioned states in the hurricane embryo which lead to tropical cyclogenesis is a central issue in contemporary meteorology in the embryo there is competition between different preconditioning mechanisms involving hydrodynamics and moist thermodynamics which can lead to cyclogenesis here systematic asymptotic methods from applied mathematics are utilized to develop new simplified moist multi scale models starting from the moist anelastic equations three interesting multi scale models emerge in the analysis the balanced mesoscale vortex bmv dynamics and the microscale balanced hot tower bht dynamics involve simplified balanced equations without gravity waves for vertical vorticity amplification due to moist heat sources and incorporate nonlinear advective fluxes across scales the bmv model is the central one for tropical cyclogenesis in the embryo the moist mesoscale wave mmw dynamics involves simplified equations for mesoscale moisture fluctuations as well as linear hydrostatic waves driven by heat sources from moisture and eddy flux divergences a simplified cloud physics model for deep convection is introduced here and used to study moist axisymmetric plumes in the bht model a simple application in periodic geometry involving the effects of mesoscale vertical shear and moist microscale hot towers on vortex amplification is developed here to illustrate features of the coupled multi scale models these results illustrate the use of these models in isolating key mechanisms in the embryo in a simplified content

late pleistocene vertebrates from northern uruguay tools for biostratigraphic climatic and environmental reconstruction abstract an updated list of vertebrates from quaternary sediments of northern uruguay is provided including new reports a detailed study of equus amerhippus neogeus was performed due to its biostratigraphic value in correlating the fossil assemblage with the lujanian stage late pleistocene early holocene the faunal association is referred to the sopas formation the only stratigraphic unit recognized three stratigraphic sections reveal the predominance of subaquous environmental deposition yucutuja and malo creeks and the development of paleosols on fluvial flood plains sopas creek the mammal content and the 14c and thermoluminescence optically stimulated luminescence ages indicate a late pleistocene age information indicating a relationship with ois3 is discussed the mammals of the sopas formation seem to be different and older than the fauna of the guerrero member of the lujan formation ecological and biogeographic information provided by the fauna is used to discuss paleoenvironments and climatic processes involved this reinforces the hypothesis of the presence of a variety of habitats composed dominantly of open areas plus some forested zones with permanent lacustrine and fluvial contexts brazilian and some patagonian vertebrates occurring together in the sopas formation lead to discussion of the nature of the fossil assemblage

factors affecting pore water hydrocarbon concentrations in puget sound sediments abstract polycyclic aromatic hydrocarbon pah and aliphatic hydrocarbon concentrations have been determined for sediments and associated pore waters collected at 2 sites 11 stations in puget sound washington northwest u s a these sediments have been contaminated to varying degrees by hydrocarbons from a creosote plant and from various combustion sources pah were not detected in pore waters of sediments whose pah were primarily derived from combustion and natural sources even though pore water concentrations predicted from sediment concentrations and two phase equilibrium partitioning models were above detection limits from most pah equilibrium partition coefficients calculated from field aqueous and solid phase data from an area contaminated with creosote agreed with laboratory derived coefficients to within a factor of 4 pore water concentrations of creosote derived aliphatic hydrocarbons increase with increasing concentration in bulk sediments however pore water concentrations of natural and contaminant aliphatic hydrocarbons are much higher than predicted by solubility data possibly due to association with nonfilterable dissolved organic matter and colloids other major factors controlling hydrocarbon pore water concentrations include differential hydrocarbon sources specific particle associations and solubility

significance of polycyclic aromatic hydrocarbons pahs in permian triassic boundary sections abstract in this study the abundances of several polycyclic aromatic hydrocarbons pahs table 1 i xxi have been measured throughout three permian triassic p tr sections from meishan south china kap stosch area east greenland and peace river basin western canada dibenzothiophene i and dibenzofuran ii were found to decrease in abundance just before or shortly after the p tr transition in all three sections while perylene iii was observed to increase in abundance at the onset of the main extinction horizon bed 25 in meishan perylene has been attributed to a wood degrading fungal source and therefore it seems possible these phenomena are related to the demise of land plants further distinct patterns of various combustion derived pahs occurring in each section imply that forest fire events occurred within the late permian and early triassic in the meishan section high amounts of combustion derived pahs pyrene iv fluoranthene v benzo a anthracene vi benzofluoranthenes sum i e vii benzo a pyrene viii benzo e pyrene ix and coronene x occur within bed 25 also containing ash attributed to the fallout from massive volcanic eruptions in siberia and or china

sedimentary hydrocarbons from a subtropical marine estuary petrogenic pyrogenic and biogenic hydrocarbons were determined in sediments from 48 sites around charlotte harbor a relatively undeveloped subtropical marine estuary along the south west coast of florida hydrocarbon concentrations generally ranged from 1 to 5 g g 1 which are lower than hydrocarbon values reported for most temperature estuarine sediments but agree well with values reported for sediments from more highly impacted subtropical estuarine systems little evidence of petrogenic or pyrogenic inputs was observed except for certain hot spots associated with marina land development and industrial activities sediments collected during the summer showed enhanced hydrocarbon concentrations over winter samples reflecting increased biogenic input from both marine and terrestrial sources data obtained in this and similar studies suggests that in these subtropical areas a steady state is established between hydrocarbon inputs and microbial degradation

glacial to postglacial transformation of organic input pathways in arctic ocean basins 1 the arctic ocean is undergoing rapid loss in ice cover with yet unknown consequences for the cycling of organic material here we examine persistent terrigenous land based alkane and polycyclic aromatic hydrocarbons with vascular plant combustion and petrogenic sources in seven cores collected from all major basins of the arctic ocean for insight as to how organic cycling at the last glacial maximum compares to the present day we find only modest changes between the glacial and postglacial sediments for atmospherically transported hydrocarbon biomarkers demonstrating that glacial sea ice was not a barrier to atmospheric inputs in stark contrast particle associated biomarkers were captured strongly at basin edges during the glacial period and much more evenly transported across basins during the postglacial period evidently the capture of organic matter shifted from the slopes to the shelves as the latter flooded during the holocene and the transpolar drift and beaufort gyre evolved from minor carriers of plant detritus from the glacial ocean margins to major modern transporters of shelf sediment to the basins this suggests that changes in organic transport currently accompanying the loss of sea ice are likely to be very different from those that occurred at the end of the last glacial period

a numerical study of deep convection in tropical cyclones idealized numerical model simulations are used to investigate the generation and evolution of vertical vorticity by deep convection in a warm cored vortex of near tropical storm strength deep convective updraughts are initiated by thermal perturbations located at different radii from the vortex axis it is found that as the location of the thermal perturbation is moved away from the axis of rotation the updraught that results becomes stronger the cyclonic vorticity anomaly generated by the updraught becomes weaker the structure of the vorticity anomaly changes markedly and the depth of the anomaly increases for an updraught along or near the vortex axis the vorticity anomaly has the structure of a monopole and little or no anticyclonic vorticity is generated in the core vorticity dipoles are generated in updraughts near or beyond the radius of maximum tangential wind speed and this structure reverses in sign with height in all cases the vorticity anomalies persist long after the initial updraught has decayed implications of the results for understanding the vorticity consolidation during tropical cyclogenesis are discussed the effects of eddy momentum fluxes associated with a single updraught on the tangential mean velocity tendency are investigated and a conceptual framework for the interpretation of these eddy fluxes is given the simulations are used to appraise long standing ideas suggesting that latent heat release in deep convection occurring in the high inertial stability region of a vortex core is more efficient than deep convection outside the core in producing temperature rise in the updraught

biomarker characterisation of an oil and its possible source rock from offshore korea bay basin abstract comparison of biomarker distributions in an oil and in sedimentary rock samples from an offshore well in korea bay basin indicates that an upper jurassic 500 m thick mudstone zone could form the source rock for the oil the organic material in this zone appears to be h rich and of sufficient abundance from pyrolysis measurements to generate oil it seems to derive primarily from bacterial lipids as reflected in high levels of bacterial hopanoids and predominance of amorphous kerogen macerals a higher plant wax contribution to the organic matter is indicated by an oep in n akanes c 20 and there may also be an autochtonous algal contribution sedimentological and biomarker evidence is consistent with input from a river delta prograding into a deep freshwater lake biomarker distributions suggest that pronounced bacterial reworking of allochthonous higher plant material had occurred in probably anoxic conditions high heat flows in a rapidly subsiding extensional basin probably account for the observed extensive aromatisation of monoaromatic steroidal hydrocarbons at a relatively early stage of sterane isomerisation

black carbon in soils and sediments analysis distribution implications and current challenges this review highlights the ubiquity of black carbon bc produced by incomplete combustion of plant material and fossil fuels in peats soils and lacustrine and marine sediments we examine various definitions and analytical approaches and seek to provide a common language bc represents a continuum from partly charred material to graphite and soot particles with no general agreement on clear cut boundaries formation of bc can occur in two fundamentally different ways volatiles recondense to highly graphitized soot bc whereas the solid residues form char bc both forms of bc are relatively inert and are distributed globally by water and wind via fluvial and atmospheric transport we summarize chronologically the ubiquity of bc in soils and sediments since devonian times differentiating between bc from vegetation fires and from fossil fuel combustion bc has important implications for various biological geochemical and environmental processes as examples bc may represent a significant sink in the global carbon cycle affect the earth s radiative heat balance be a useful tracer for earth s fire history build up a significant fraction of carbon buried in soils and sediments and carry organic pollutants on land bc seems to be abundant in dark colored soils affected by frequent vegetation burning and fossil fuel combustion thus probably contributing to the highly stable aromatic components of soil organic matter we discuss challenges for future research despite the great importance of bc only limited progress has been made in calibrating analytical techniques progress in the quantification of bc is likely to come from systematic intercomparison using bcs from different sources and in different natural matrices bc identification could benefit from isotopic and spectroscopic techniques applied at the bulk and molecular levels the key to estimating bc stocks in soils and sediments is an understanding of the processes involved in bc degradation on a molecular level a promising approach would be the combination of short term laboratory experiments and long term field trials

the brazilian megamastofauna of the pleistocene holocene transition and its relationship with the early human settlement of the continent abstract one of the most intriguing questions regarding the brazilian late quaternary extinct megafauna and homo sapiens is to what extent they coexisted and how humans could have contributed to the former s extinction the aim of this article is to review the chronological and archaeological evidences of their coexistence in brazil and to evaluate the degree of direct interaction between them critical assessment of the brazilian megafauna chronological data shows that several of the late pleistoscene early holocene dates available so far cannot be considered reliable but the few that do suggest that at least two species catonyx cuvieri ground sloth smilodon populator saber toothed cat survived until the beginning of the holocene in southeast brazil archaeological data indicates that the first human groups arrived in brazil and were inhabiting this region during the last millennia of the pleistocene and consequently they coexisted with the extinct fauna in some parts of brazil for at least one thousand years there is no robust evidence favoring any kind of direct interaction between humans and megafauna prior to their extinction to date it is not possible to properly judge the indirect influence of humans landscape transformation introduction of predators among others in this extinction event intense and to some extent unique climate changes between the last glacial maximum and the holocene favors the interpretation that they had a major contribution to the megafauna extinction although the scarcity of data impedes the proper testing of this hypothesis

electron spin resonance dating of the southern brazilian pleistocene mammals from touro passo formation and remarks on the geochronology fauna and palaeoenvironments abstract quaternary mammals from touro passo formation southern brazil rio grande do sul state were studied in the 1970s and assigned to the pleistocene holocene transition approximately between 13 000 and 3500 bp subsequent dating by thermoluminescence indicated that the sediments of this formation are older between 42 and 15 ka bp and ages obtained by ams in mollusks and 14c of charcoal ranged from 16 to 10 ka bp however none of these ages were obtained directly from vertebrates in this work four teeth samples of artiodactyla indet gomphoteriidae indet 2 samples called g1 and g2 and toxodon sp from ponte velha i locality touro passo creek were dated by electron spin resonance esr the results are 34 6 ka for artiodactyla 23 5 ka for g1 28 3 ka for g2 and 19 3 ka for toxodon sp the variation in the ages of the materials corroborates the hypothesis that the fossils of ponte velha i locality have been reworked the dating contributes to the chronology of the brazilian pleistocene mammals and corroborates the previous interpretations on the timing of deposition of touro passo formation during the late pleistocene

alkane and pah provenance and potential bioavailability in coastal marine sediments subject to a gradient of anthropogenic sources in british columbia canada abstract marine coastal areas of british columbia canada are subject to a gradient of increasing anthropogenic sources from pristine areas in the north to the more urbanised areas of the south along the gradient the relative contributions of polycyclic aromatic hydrocarbons pahs from multiple natural and anthropogenic sources are not well understood but concerns linger about bioavailability and consequent risks to marine biota composition patterns and principal components analysis pca models for surface sediment and core samples collected along this transect indicate that samples from the urbanised vancouver area have the highest proportions of tricyclic terpane hopane and sterane biomarkers ucm unresolved complex mixture the alkyl fluoranthene pyrene and benz a anthracene chrysene series and most parent pahs those from hecate and queen charlotte straits and other locations in the strait of georgia have on the other hand higher proportions of the resolved alkanes and petrogenic alkyl naphthalene fluorene dibenzothiophene and phenanthrene anthracene series pah ratios clearly indicate a predominance of combustion sources for the four ring and higher parent pahs for all the sediments most samples have values close to the biomass solid fuel and liquid fuel combustion borderline for ratios of the major pahs but liquid fuel combustion input dominates closer to urbanised locations ratios also suggest similar pyrogenic and petrogenic inputs between central hecate strait and reference sediments from hecate strait through to queen charlotte strait which indicates that biomass combustion and immature coal formations are the major putative respective sources for the reference areas alkyl pah ratios for the c3 and c4 naphthalenes c2 and c3 phenanthrenes and 3 and 2 methylchrysene reflecting terrigenous vascular plant sources and petroleum maturity exhibit marked differences between comox bituminous coal and alberta sweet mixed blend asmb oil and reveal that the petrogenic input in all of the sediments is non biodegraded ratios of these alkyl pahs with multiple substituents indicate that the sediment samples in the northern strait of georgia closest to the comox coal field receive relatively constant input of eroded coal while those in the southern strait of georgia and vancouver harbour show a composition closest to asmb oil pahs associated with liquid fossil fuel combustion and petroleum discharges adjacent to urbanised areas are expected to be fully bioavailable to marine food webs while the char from biomass combustion and coal from immature deposits in more remote areas would have limited bioavailability this implies that biota in remote areas of hecate strait queen charlotte sound are likely not adapted to the presence of oil and thus would be more sensitive to exposure to spilled oil than those in the more impacted environments in southern british columbia

subsurface combustion in mali refutation of the active volcanism hypothesis in west africa surface heat anomalies have been known in the timbuktu region in northern mali for more than a century since about 1960 several authors have argued that these heat anomalies are caused by incipient volcanic and hydrothermal activity surface temperatures as high as 765 c were measured locally in january 2002 and smoke emanated from holes and fractures in the ground we demonstrate that subsurface combustion of organic material is the source of the heat and the gases several square kilometers are currently active or have been affected by subsurface fires since 2001 self ignition during biological degradation of organic rich layers in the lacustrine deposits is the most likely mechanism that started the subsurface combustion that caused the heat anomalies in the area an important consequence of this conclusion is that west africa should still be regarded as volcanologically inactive and that possible reactivations of the major ew trending guinean nubian lineament are not associated with volcanism we suggest that the subsurface combustion in the timbuktu region today represents a phenomenon with a very long record in the trans saharan region

predominance of terrigenous organic matter in cretaceous marine fore arc sediments japan and far east russia abstract marine cretaceous sequences of the eastern margin of northeast asia show remarkable predominance of terrestrial woody kerogens over marine algal ones microscopic study on 18 hemipelagic mudstones collected from three dated albian santonian sections in far east asia established that inertinite especially semifusinite and vitrinite were predominant macerals in all samples rare 1 liptinite detected by fluorescence indicates little contribution from marine organic matter to the total maceral composition the predominance of semifusinite over vitrinite suggests that occasional wildfire played a primary role in supplying resistant organic matter to the sedimentary basin during the late cretaceous polycyclic aromatic hydrocarbons pahs of pyrolytic origin from all selected horizons also support paleo wildfires non alkylated benzo a pyrene benzo e pyrene benzo g h i perylene and coronene predominate over alkylated ones vitrinite reflectance that exhibits large intra sample variation up to 2 0 may indicate various oxidation levels for the precursor of vitrinite wood fragments during biodegradation transportation and early diagenesis before reaching the depositional site in the basin similar vitrinite reflectance populations between the three sections studied suggest similar oxidation processes and transportation mechanisms for non pyrolysed portion of organic matter around these depositional sites the kerogen from the studied marine sections offers a unique opportunity for paleoenvironmental research and understanding land sourced environments

c 27 c 29 monoaromatic anthrasteroid hydrocarbons in cretaceous black shales the structural elucidation of aromatic steroid hydrocarbons occurring in sediments and petroleums has been the subject of increasing interest during recent years1 7 aromatization of the precursor sterols of marine origin has been shown to start at early stages of diagenesis in immature sediments8 9 in elucidating these first aromatization reactions we have recently identified two major series of ring a monoaromatic steroids 1 and 2 fig 1 in cretaceous black shales from the southern and eastern north atlantic collected during the deep sea drilling project dsdp 8 we report here the identification of two novel series of geochemical markers the ring b mono aromatic anthrasteroid hydrocarbons 3 and 4 as the two other major series occurring in the same immature dsdp samples fig 1

tropical cyclone formation in a sheared environment a case study abstract the development of hurricane danny 1997 from depression to hurricane was examined using cloud to ground lightning data reconnaissance aircraft data and satellite imagery vertical wind shear between 850 and 200 hpa of 5 11 m s 1 produced persistent downshear convective outbreaks that became progressively more intense and closer to the center during the development early in the period the storm intensified steadily in the presence of this downshear convection during the last and most intense outbreak a second vortex appeared to develop within the convection evidence is presented that the new downshear vortex became the dominant vortex and absorbed the original based on these events it is hypothesized that the presence of moderate vertical wind shear accelerated the early development process equivalent potential temperature fields within 500 m of the surface were examined only well after the period of vortex interaction did the characteristic mature tropical cyclone radial profile of eq

polycyclic aromatic hydrocarbons of pyrolytic origin in ancient sediments evidence for jurassic vegetation fires abstract polycyclic aromatic hydrocarbon pah distributions in an upper jurassic succession from offshore korea bay basin were consistent with a pyrolytic source being dominated by non alkylated species levels of these pahs were significantly higher in samples containing abundant fusinite macerals which are believed by some to be the product combustion the data were consistent with a pah origin from periodic conflagration throughout the upper jurassic of vegetation adjacent to a tectonically formed lake distribution of pahs exhibited some differences from those of combustion origin in recent and some ancient sediments and were characterized by the dominance of the highly peri condensed compounds benzo e pyrene benzo g h i perylene and coronene this characteristics reflects either preferential formation or preferential preservation under the prevailing sedimentary conditons of the highly peri condensed structures

changes of palaeoenvironmental conditions recorded in late devonian reef systems from the canning basin western australia a biomarker and stable isotope approach abstract although the late devonian extinctions were amongst the largest mass extinction events in the phanerozoic the causes nature and timing of these events remain poorly restrained in addition to the most pronounced biodiversity loss at the frasnian famennian f f boundary and the end famennian there were also less extensively studied extinction pulses in the middle to late givetian and the frasnian here we used a combination of palynological elemental molecular and stable isotope analyses to investigate a sedimentary record of reef systems from this time period in the canning basin western australia the acquired data generally showed distinct variations between sediments from i the time around the givetian frasnian g f boundary and ii later in the frasnian and indicated a distinct interval of biotic stress particularly for reef builders in the older sediments alterations of pristane phytane ratios gammacerane indices chlorobi biomarkers dkerogen and chroman ratios describe the change from a restricted marine palaeoenvironment with an anoxic euxinic hypolimnion towards a presumably open marine setting with a vertically mixed oxic to suboxic water column simultaneous excursions in 13c profiles of carbonates organic matter om and hydrocarbons in the older sediments reflect the stratification induced enhancement of om recycling by sulfate reducing bacteria alterations in sterane distributions and elevated abundances of methyltrimethyltridecylchromans mttcs and perylene indicate an increased terrigenous nutrient input via riverine influx which would have promoted stratification phytoplankton blooms and the development of lower water column anoxia the detected palaeoenvironmental conditions around the g f boundary may reflect a local or global extinction event our data furthermore suggest a contribution of the higher plant expansion and photic zone euxinia to the late devonian extinctions consistent with previous hypotheses furthermore this work might contribute to the understanding of variations in devonian reef margin and platform top architecture relevant for petroleum exploration and development in the global devonian hydrocarbon resources

organic geochemistry of the early toarcian oceanic anoxic event in hawsker bottoms yorkshire england a comprehensive organic geochemical investigation of the hawsker bottoms outcrop section in yorkshire england has provided new insights about environmental conditions leading into and during the toarcian oceanic anoxic event t oae 183 ma rock eval and molecular analyses demonstrate that the section is uniformly within the early oil window hydrogen index hi organic petrography polycyclic aromatic hydrocarbon pah distributions and tricyclic terpane ratios mark a shift to a lower relative abundance of terrigenous organic matter supplied to the sampling locality during the onset of the t oae and across a lithological transition unlike other ancient intervals of anoxia and extinction biomarker indices of planktonic community structure do not display major changes or anomalous values depositional environment and redox indicators support a shift towards more reducing conditions in the sediment porewaters and the development of a seasonally stratified water column during the t oae in addition to carotenoid biomarkers for green sulfur bacteria gsb we report the first occurrence of okenane a marker of purple sulfur bacteria psb in marine samples younger than 1 64 ga based on modern observations a planktonic source of okenane s precursor okenone would require extremely shallow photic zone euxinia pze and a highly restricted depositional environment however due to coastal vertical mixing the lack of planktonic okenone production in modern marine sulfidic environments and building evidence of okenone production in mat dwelling chromatiaceae we propose a sedimentary source of okenone as an alternative lastly we report the first parallel compound specific c13 record in marine and terrestrial derived biomarkers across the t oae the c13 records of short chain n alkanes acyclic isoprenoids and long chain n alkanes all encode negative carbon isotope excursions cies and together they support an injection of isotopically light carbon that impacted both the atmospheric and marine carbon reservoirs to date molecular c13 records of the t oae display a negative cie that is smaller in magnitude compared to the bulk organic c13 excursion although multiple mechanisms could explain this observation our molecular petrographic and rock eval data suggest that variable mixing of terrigenous and marine organic matter is an important factor affecting the bulk organic c13 records of the t oae

tropical cyclogenesis and vertical shear in a moist boussinesq model tropical cyclogenesis is studied in the context of idealized three dimensional boussinesq dynamics with perhaps the simplest possible model for bulk cloud physics with low altitude input of water vapour on realistic length and time scales numerical simulations capture the formation of vortical hot towers from measurements of water vapour vertical velocity vertical vorticity and rain it is demonstrated that the structure strength and lifetime of the hot towers are similar to results from models including more detailed cloud microphysics the effects of low altitude vertical shear are investigated by varying the initial zonal velocity profile in the presence of weak low level vertical shear the hot towers retain the low altitude monopole cyclonic structure characteristic of the zero shear case starting from zero velocity some initial velocity profiles with small vertical shear can have the effect of increasing cyclonic predominance of individual hot towers in a statistical sense as measured by the skewness of vertical vorticity convergence of horizontal winds in the atmospheric boundary layer is mimicked by increasing the frequency of the moisture forcing in a horizontal subdomain when the moisture forcing is turned off and again for zero shear or weak low level shear merger of cyclonic activity results in the formation of a larger scale cyclonic vortex an effect of the shear is to limit the vertical extent of the resulting emergent moist vortex for stronger low altitude vertical shear the individual hot towers have a low altitude vorticity dipole rather than a cyclonic monopole the dipoles are not conducive to the formation of larger scale vortices and thus sufficiently strong low level shear prevents the vortical hot tower route to cyclogenesis the results indicate that the simplest condensation and evaporation schemes are useful for exploratory numerical simulations aimed at better understanding of competing effects such as low level moisture and vertical shear

vascular plant biomarkers as proxies for palaeoflora and palaeoclimatic changes at the dogger malm transition of the paris basin france abstract vascular plant biomarkers are used here as a chemostratigraphic tool for tracing both palaeoflora and palaeoclimatic changes during the callovian and oxfordian in the paris basin the retene cadalene ratio shows low values in claystones from the middle callovian to the end of the lower oxfordian then increases drastically from the end of the lower oxfordian cordatum zone synchronously with the progressive development of the oxfordian carbonate platform the relative proportion of retene a conifer biomarker is strongly correlated with the abundance of some of its diagenetic precursors and with saturated diterpanes some of these are very common and abundant in the pinaceae family while specific markers for non pinaceae conifers are not detected thus the increase in the retene cadalene ratio around the cordatum zone reflects the rising proportion of pinaceae on the london brabant massif which was the nearest land from the locations studied as pinaceae show many morphological adaptations to dry climate compared to the other plants reported in the jurassic taphofloras of the paris basin their increasing proportion indicates an increasing aridity this climatic change is also supported by published geochemical palaeobiogeographical palynological palaeobotanical and mineralogical data a comparable increase in the relative proportion of retene was also described for the oxfordian of western australia which could be an argument for a worldwide increase in aridity at the end of the lower oxfordian

isomerisation rearrangement and aromatisation of steroids in distinguishing early stages of diagenesis abstract the distributions of proposed reactants and products of stages of early diagenesis of steroid hydrocarbons have been studied by gc and gc ms in a variety of downhole sequences of dsdp cores of various ages which include the san miguel gap walvis ridge gulf of california and falkland plateau the compounds comprise aliphatic and aromatic hydrocarbons such as diasterenes monoaromatic anthrasteroids and spirosterenes from the study of the progress of proposed reactions and of presumed product reactant relationships a pattern emerges that extractable lipid distributions can provide a means of distinguishing levels of early diagenesis which cannot be recognised readily from other methods a number of diagentic trends are evident such as progressive isomerisation at c 20 in diasterenes which occurs at different relative rates and temperature ranges in sediment sequences with different heat fluxes such studies allow investigation of the changes in biological marker compounds in the part of the continuum between changes during sediment deposition and the advent of catagenesis

an air sea interaction theory for tropical cyclones part ii evolutionary study using a nonhydrostatic axisymmetric numerical model abstract in part i of this study an analytical model for a steady state tropical cyclone is constructed on the assumption that boundary layer air parcels are conditionally neutral to displacements along the angular momentum surfaces of the hurricane vortex the reversible thermodynamics implied by this assumption allows the mature storm to be thought of as a simple carnot engine acquiring heat at the high temperature ocean surface and losing heat near the low temperature tropopause although the oceanic heat source is universally recognized as the sine qua non for the mature hurricane there is also wide acceptance of conditional instability of the second kind cisk which makes no specific reference to surface heat fluxes as the formative mechanism this ambivalence is seen in that all numerical simulation studies find it essential to have transfer from the ocean surface yet all start from a conditionally unstable atmosphere the hypothesis put forward in part i based on the steady state theory is t

δ13c of polycyclic aromatic hydrocarbons to establish the facies variations in a fluvial deltaic triassic record dampier sub basin western australia abstract the 13 c of polycyclic aromatic hydrocarbons pahs was measured in a series of triassic and jurassic source rocks from the dampier sub basin carnarvon basin north west shelf of australia these sequences correspond to fluvial deltaic systems which integrate the mungaroo brigadier and legendre formations and the organic matter has been assigned as mixed terrigenous marine material the relative abundance of the pahs was plotted against the difference between 13 c values of 1 3 6 7 tetramethylnaphthalene temn and each pah we demonstrated here that samples plotting below 0 for 13 c combustion marker 1 3 6 7 temn are related to delta plain front deltaic facies or coaly fluvial deltaic facies e g samples from the mungaroo formation north rankin 5 goodwyn 9 and goodwyn 5 wells whereas the positive region for 13 c combustion marker 1 3 6 7 temn is assigned to transitional facies deposited under an estuarine lagoonal environment with a high sapropelic contribution brigadier formation and marginal marine environment legendre formation a similar separation for the samples was obtained with phenanthrene and other pahs the 13 c of pahs in combination with their distributions can be used to establish the facies type i e delta plain front deltaic from estuarine lagoonal in a dominantly fluvial deltaic record our research provides new tools to take into account for further applications in fluid source rock correlation studies which represent the main challenge in assessing petroleum systems in the sub basin