ferromanganese oxide deposits from the central pacific ocean i encrustations from the line islands archipelago abstract chemical and mineralogical analyses of a well controlled suite of ferromanganese encrustations from the line islands archipelago central pacific suggest that they represent purely hydrogenous deposits i e they have formed through the slow accumulation of trace metal enriched oxides directly from the water column mineralogically they consist predominantly of mno2 and amorphous feoohxh2o compositionally they are similar to mno2 nodules from adjoining basinal areas but are enriched in both mn mean 20 4 max 29 3 and co mean 0 55 max 1 57 mno2 is the most important trace metal bearing phase strong associations are noted between it and co mo ni zn and cd whilst only be is associated specifically with feooh v sr and pb are partitioned between the authigenic oxide phases whilst ti most probably occurs as tio2xh2o cu is contained in both aluminosilicate contaminant phases and fe oxide phases these relations are considered to reflect the differing scavenging behaviour of mn and fe oxides in the water column crusts from 1 2 km are enriched in mn and the mn related elements and exhibit higher mn fe ratios than deeper crusts which are compositionally constant the higher mn fe ratios may result from a supply of mn from continental borderland sediments at these depths which is transported horizontally by advective diffusive processes since manganophile elements are enriched relative to mn in the 1 2 km crusts it is considered that the supply of mn is scavenged by existing oxides is oxidised and effectively occludes them a higher proportion of oxide particles thus exhibit mn oxide scavenging properties in the 1 2 km depth zone the increased vertical flux of mn resulting from the supply at 1 2 km is not reflected by higher mn fe ratios in deeper crusts so that the vertical flux of oxides is not simply related to the standing crop the mn fe ratios of the crusts thus reflect the composition of suspended oxides at similar depths

drivers of holocene sea level change in the caribbean abstract we present a holocene relative sea level rsl database for the caribbean region 5 n to 25 n and 55 w to 90 w that consists of 499 sea level index points and 238 limiting dates the database was compiled from multiple sea level indicators mangrove peat microbial mats beach rock and acroporid and massive corals we subdivided the database into 20 regions to investigate the influence of tectonics and glacial isostatic adjustment on rsl we account for the local scale processes of sediment compaction and tidal range change using the stratigraphic position overburden thickness of index points and paleotidal modeling respectively we use a spatio temporal empirical hierarchical model to estimate rsl position and its rates of change in the caribbean over 1 ka time slices because of meltwater input the rates of rsl change were highest during the early holocene with a maximum of 10 9 0 6 m ka in suriname and guyana and minimum of 7 4 0 7 m ka in south florida from 12 to 8 ka following complete deglaciation of the laurentide ice sheet lis by 7 ka mid to late holocene rates slowed to

classification of huminite iccp system 1994 abstract in the new classification iccp system 1994 the maceral group huminite has been revised from the previous classification iccp 1971 int handbook coal petr suppl to 2nd ed to accommodate the nomenclature to changes in the other maceral groups especially the changes in the vitrinite classification iccp 1998 the new vitrinite classification iccp system 1994 fuel 77 349 358 the vitrinite and huminite systems have been correlated so that down to the level of sub maceral groups the two systems can be used in parallel at the level of macerals and for finer classifications the analyst now has according to the nature of the coal and the purpose of the analysis a choice of using either of the two classification systems for huminite and vitrinite this is in accordance with the new iso coal classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals

long term change in tidal dynamics and its cause in the pearl river delta china abstract this paper focuses on identifying changes in the tidal range and the duration of the flood tide in the pearl river delta region china mann kendall test and regression methods are employed to verify the existence of trends in the annual tidal range and duration series from the 1950s to 2005 at 17 stations in the 3 major tributaries of the delta the research results indicate that generally there is an increasing trend in the tidal range and flood tide duration at most of the stations in the channel network moreover the more upstream the location of the station the more obvious the change in trend is and these increasing trends are all significant at the stations in the upper part of the delta specifically the tidal range at shilong station in the east river has increased abruptly since the middle of the 1980s such that the mean level of post 1990 data is approximately three times that for pre 1985 most stations near the mouth of the estuary show significant downward trends in the tidal range and flood tide duration results of the intersection point of the mann kendall test curves for these pearl river delta stations appear mostly in 1980s 1990s indicating that a noticeable change point occurs during this period human activities in the pearl river delta reached their peak during the 1980s among these large scale and long term sand excavation modified the hydrodynamic regime dramatically in a way that increased the water depth and lowered the level of the riverbed leading to an increased tidal prism and upstream movement of the tidal limit land reclamation is also likely to have had a relatively large effect on the tidal range and flood tide duration at stations near to the estuary mouth changes in other factors such as freshwater flow and sea level rise seem to be of relatively minor importance it is noteworthy that in a dry season the tidal dynamics are greatly enhanced and has resulted in strong saltwater intrusion into the estuary in recent years

petrological and organic geochemical investigation of recent peats with known environments of deposition abstract a series of recent peat samples from tropical sub tropical and temperate locations were investigated using coal petrographical and organic geochemical techniques maceral and biomarker compositions were examined to see if they correlated or diverged from the known environment of deposition of the peats the proportion of humotelinite was related to the water depth and the frequency of dry periods the ph and trophic level have a modifying influence on the preservation of tissues furthermore the proportions of sclerotinite in the peats seem to reflected the oxygen status in the mire which was also mirrored in the abundance of humic and fulvic acids a facies diagram was calculated for the peat samples to see how maceral indices would fare in interpreting their known environments of deposition the results proved to be generally unsuccessful as the herbaceous and woody peats did not always give the predicted high humodetrinite and humotelinite compositions respectively the aliphatic hydrocarbon fraction from the extracts of the peat samples show that mainly odd numbered n alkanes are present diterpenoids triterpenoids and hopanoids were found in most samples and were mainly unsaturated in nature the relative proportion of hopanoids in pears appears to be related to bacterial activity in acidic environments de a triterpenoids were also detected in the peat stage of diagenesis in an angiosperm dominated peat type mariscus polycyclic aromatic triterpenoids were present in the aromatic fraction of the extract their occurrence and proportion appears to be related to the degree of humification in a taxodium peat mono di and triaromatic diterpenoids were detected the presence of these aromatic biomarkers indicate the rapid formation of these compounds in the peat stage mainly mediated by microbial activity

estimating growth rates of ferromanganese nodules from chemical compositions implications for nodule formation processes abstract using available information on the accretion rates and the bulk chemical compositions of oceanic ferromanganese nodules it can be shown that the accumulation rate of manganese is proportional to the square of the accumulation rate of iron this relationship has been used to derive an equation that predicts nodule growth rates from their chemical compositions the equation accurately predicts growth rates up to about 50 mm 10 6 yr but yields incorrect rates for faster growing concretions from this relationship nodules underneath water of high primary productivity grow most rapidly and accumulate transition metals most rapidly however nodules from regions of highest primary productivity do not have the highest concentrations of nickel and copper reduction of manganese within the sediment column and remobilization of a fraction to the surface sediments adds manganese to nodules without substantially augmenting the supply of other transition elements the addition of remobilized manganese to the nodule dilutes the concentrations of nickel copper and iron even though their rates of accumulation are also high

a geotechnical correction for post depositional sediment compression examples from the forth valley scotland fine grained sediments usually suffer post depositional compression compaction which reduces bed thickness and lowers the elevations of sample positions and marker horizons this reduction has been calculated for two general cases using geotechnical theory and a correction decompaction factor is presented that can be applied to many field situations its use is illustrated by two examples from the clay sediments of the claret formation of the forth valley in the first the correction is calculated for 14c samples from the bothkennar research site near grangemouth and the effect on the reconstruction of water depths is discussed in the second example corrections are obtained for published sea level index points from former shorelines in the forth valley using a method for a postiori estimation of geotechnical data general conclusions are drawn between the size of the correction and the sample position relative to the local depocentre some applications to palaeotidal modelling are also suggested 1998 john wiley sons ltd

deciphering holocene sea level history on the u s gulf coast a high resolution record from the mississippi delta published holocene relative sea level rsl curves for the u s gulf coast are in mutual conflict with some characterized by a smooth rsl rise akin to widely accepted eustatic sea level curves versus others including several recent ones that are characterized by a conspicuous stair step pattern with prolonged millennium scale rsl stillstands alternating with rapid meter scale rises in addition recent work in texas and alabama has revitalized the notion of a middle holocene rsl highstand estimated at 2 m above present mean sea level an extensive sampling program in the mississippi delta louisiana focused on the collection of basal peats that accumulated during the initial transgression of the pre existing consolidated pleistocene basement we used stable carbon isotope ratios to demonstrate that many of these samples accumulated in environments affected by frequent saltwater intrusion in the 30 cm zone between mean spring high water and mean sea level and we selected plant macrofossils that were subjected to ams 14c dating nearly 30 sea level index points from a 20 km2 study area on the eastern margin of the delta suggest that rsl rise followed a relatively smooth trend for the time interval 8000 3000 cal yr b p thus questioning the occurrence of major rsl stillstands alternating with abrupt rises given the narrow error envelope defined by our data set any sea level fluctuations if present would have amplitudes of 1 m although a true middle holocene highstand never occurred in the mississippi delta the high level of detail of our time series enables a rigorous test of this hypothesis correction of our data set for a hypothetical tectonic subsidence rate of 1 1 mm yr 1 assuming a constant subsidence rate compared to the tectonically relatively stable adjacent coast of texas leads to sea levels near 2 m above present during the time interval 6000 4000 cal yr b p however this model also implies a rsl position near 2 m around 8000 cal yr b p which is inconsistent both with data of this age from texas as well as with widely accepted sea level data from elsewhere we therefore conclude that a middle holocene highstand for the u s gulf coast is highly unlikely and that the entire area is still responding glacio isostatically by means of forebulge collapse to the melting of the laurentide ice sheet

the genesis of coal from the viewpoint of coal petrology abstract the genesis of the microscopic constituents of coal macerals and of maceral associations microlithotypes representing various coal facies is discussed in the light of recent advances that have been made in the study of coals and modern peats peat microscopy especially promoted the understanding of humification and biological gelification both of which are decisive for the genesis of huminites vitrinites in brown coals and hard coals respectively microbial activity during peatification has been documented by chemists microbiologists and petrologists and recently by electron microscopical observations in coals this activity leads to the incorporation of lipid substances into the humic matter and later influences the chemical physical and technological properties of vitrinites geochemical gelification transforms the huminites of brown coals into the vitrinites of bituminous coals and is probably caused by the onset of bitumen generation in coal in this process the hydrogel brown coal is transformed to the bitumogel bituminous coal coal as a source rock for oil has become an important research subject for coal petrologists and oil exploration the formation of more or less liquid bitumen and its later cracking to gaseous hydrocarbons leads to the coalification jumps of the macerals especially liptinites and vitrinites and to the generation of secondary macerals like exsudatinite bitumen and micrinite dead carbon bituminization in coal has been revealed by the use of fluorescence microscopy which also found the presence of new liptinite macerals bituminite fluorinite and exsudatinite and suggests a higher proportion of algal material in coals than was thought earlier the genesis of various types of inertinite macerals will probably become an increasingly important subject of research especially with regard to rank inertinites that seem to attain their high inertinitic reflectance initially during coalification besides the origin of macerals the origin of various coal facies in terms of maceral associations is considered in relation to the palaeogeographic depositional milieu the peat forming vegetation palaeoclimate water and nutrient supply acidity marine and calcareous influence and fire with examples from euramerican carboniferous coals gondwana coals and tertiary brown coals vegetation water and oxygen supply eh conditions are most important for the generation of coal facies vegetation has been reconstructed with the help of palaeobotany including palynology cuticular analysis and wood anatomy in brown coals and with the study of petrified permineralized peats preserved in coal balls the microscopical investigations of botanically recognizable plant remains isolated from coals or accompanying rocks has been especially informative however the results of palynological and cuticular analyses should be evaluated with caution considering the varying resistance of palynomorphs and cuticles and in the case of palynomorphs their possible extrapaludal origin microscopical studies of modern peats that were derived from different types of vegetation growing in different hydrological environments have been very helpful in interpreting coal facies especially in brown coals the much disputed origin of brown coal lithotypes is considered in detail for hard coals there seems to be agreement that coal layers rich in vitrites and liptinite poor clarite were deposited in wet forest swamps that microlayered liptinite rich clarites are sub aquatic humic muds and that inertinite rich durites represent oxidized peats the origin of liptinite rich durites is controversial either subaquatic muds or oxidized peats the latter perhaps from raised bogs a recent trend in the literature is the assumption that many if not all mineable coal seams have been deposited in raised bogs under ombrogenous oligotrophic conditions although raised bogs with a dense arborescent vegetation are known from borneo it seems not probable that most seams which were deposited in foredeeps or steadily sinking graben zones are of ombrogenous origin although a succession from relatively wet and eutrophic to relatively dry and oligotrophic conditions may be true for occasional seams but as in modern peats striking changes of coal facies are commonly caused by hydrological events e g inundations as a consequences of crevasses or of fires that burned the peat the origin of the inertinite rich gondwana coals is discussed in relation to their specific climatic conditions and a comparison with sub arctic peats is recommended coals influenced by marine and calcareous conditions are characterized by high contents of sulfur and pyrite as well as by hydrogen rich vitrinites with a relatively low reflectance and high fluorescence all due to a strong bacterial activity in peats of low acidity proposals for further research are made in the conclusions

relationship between morphology and composition of manganese nodules from the central indian ocean abstract the central indian ocean basin nodules exhibit a wide range of morphologies and compositions based on size shape and surface texture spheroidal nodules having a diameter between 2 and 4 cm and surface textures ranging from smooth to coarsely granular or of intermediate nature are the most common the nodule facies and their compositions are influenced by the underlying sediment through which they receive some of their constituents for example nodules with rough surface texture which are associated with siliceous radiolarian sediments are comparatively large have higher mn fe ratios and higher ni and cu contents and have lower contents of fe and co compared to the smaller smooth surfaced nodules associated with red clays additionally the shapes of the nodules reflect in part the time of initiation of growth of nodules and bottom current characteristics the nature size and abundance of botryoids are perhaps responsible for the coarse mammillated surface texture of the nodules and influence their geochemical characteristics the association of coarse texture with the siliceous sediments reflects the precipitation of larger particles of manganese oxides through the larger pore spaces of the sediment as a result of the enhanced early diagenetic effects the smooth texture in contrast reflects the direct supply of manganese oxides from the overlying bottom water as a result of their precipitation as authigenic oxyhydroxides

deltas radiocarbon dating and measurements of sediment storage and subsidence in holocene marine deltaic sequences there is no simple relationship between radiocarbon age and depth of sampling the nile and ganges brahmaputra deltas show remarkably similar radiocarbon age depth relationships 1 most radiocarbon dates by conventional and accelerator mass spectrometric ams analyses are older some by 4000 yr than reasonably expected 2 dates are commonly inverted i e older upcore and 3 sample dates at delta surfaces commonly exceed 2000 yr b p these anomalous age depth phenomena are in part a response to reservoir effects introduction of old carbon and emphasized herein influence of sediment storage and remobilization that prevail in fluvial and delta plains in fluvial systems sediment generally is not transported in a single episode from its original source area to the sea rather material transported from upland reaches and river valley to coast is subject to a repeated series of depositional burial and erosional events induced by episodic flooding overbank sedimentation and channel migration because sediment is likely to be temporarily stored in the delta plain it is difficult to determine the time of a sediment9s final deposition and burial at a delta site a successful strategy requires use of several independent dating methods including ams analyses of in situ basal peats and fossils and where possible archaeological evaluation of associated artifacts that are in place accurate dates are needed for reliable measurement of rates of delta plain aggradation and land subsidence information to help implement effective coastal protection measures

organic geochemistry of the lower miocene oberdorf lignite styrian basin austria its relation to petrography palynology and the palaeoenvironment abstract in the oberdorf trough at the northwestern margin of the styrian basin austria an up to 36 m thick lower miocene ottnangian lignite seam occurs within the fluvial koflach voitsberg formation previous results indicate that the lignite originated in a topogenous mire within a wet forest swamp palaeoenvironment differences in soluble organic matter som yield of borehole samples from the lignite seam are related to free lipids present in plant waxes or resins and the presence of thermally labile polymers indicated by the contents of liptinite macerals i e resinite suberinite and liptodetrinite the n alkane distribution patterns are dominated by high molecular weight lipids with marked odd over even predominance originating from plant waxes a contribution of algae to the even numbered short chain lipids observed in considerable amounts in the footwall sediments is proposed terpenoid biomarkers characteristic for conifers and angiosperms were detected consistent with palynomorphic spectra which are dominated by forest swamp pollen taxodiaceae cupressaceae and pollen from plants living in a mixed mesophytic forest excellent relationships between higher plant biomarker composition and palynologic data indicate that the organic geochemical results reflect the varying inputs of coniferales vs angiosperms the data further imply that cuparene may be used for taxonomical differentiation of coniferales families organic geochemical data provide evidence that the content of land plant derived biomarkers is controlled by the input of resin rich conifers concentrations of hopanoids dominated by hop 17 21 ene generally increase towards the top of the lignite a section characterised by high extents of aromatisation of triterpenoid biomarkers the results suggest that the aromatisation of angiosperm derived biomarkers may be governed by the activity of anaerobic rather than by aerobic bacteria however changes in the depositional environment and palynologic facies during peat formation probably influenced the origin and fate of angiosperm derived triterpenoids the results indicate how biomarker composition may contribute to the evaluation of environmental changes cross correlations of organic geochemical parameters with palynological data and petrography based facies indicators will provide further insights in the peat forming vegetation and biogeochemical activities in the mire

holocene relative sea level change and crustal movement in the southwestern netherlands abstract sea level data collected by jelgersma 1961 from zeeland in the southwestern netherlands show an anomalously high time depth position with respect to sea level curves established for the rest of the netherlands until now it was not clear whether this was related to differential crustal movements a higher tidal range and or to groundwater influenced peat growth above contemporaneous sea level new radiocarbon dates from the base of the basal peat in zeeland and the adjacent estuarine flood plain of the river scheide in belgium have a considerably lower time depth position than the original data of jelgersma 1961 comparison of the lowest mean sea level msl time depth points from the study area with a reference msl error band for the western netherlands yields a maximum crustal uplift of zeeland relative to the western netherlands of about 0 17 m 1000 yr over the last 8000 yrs cal b p a regional msl envelope for the southwestern netherlands has been constructed by correcting the reference msl error band with this maximum rate of relative uplift the new regional maximum msl error band plots significantly below the zeeland curve and the zeeland data points of jelgersma 1961 1966 but is still higher than msl curves established for the rest of the netherlands the remaining vertical distance of the data of jelgersma to the new zeeland msl error band is attributed to early basal peat growth above contemporaneous msl primarily due to a groundwater gradient effect on the gently inclined pleistocene subsoil the sea level index points with the lowest time depth position all come from locations close to or within the late pleistocene palaeovalley of the river scheide this was probably due to the slope of the regional groundwater table towards the palaeovalley resulting in better drainage conditions on the valley sidewalk peat could only develop under the direct influence of the river water level which was controlled by sea level rise this suggests that comparable palaeovalleys on other coastlines of the north sea or elsewhere offer considerable potential for sea level research if the topography of the compaction free substratum is well known

organic facies and depositional palaeoenvironment of lignites from rio maior basin portugal abstract the rio maior basin portugal is a tectonic depression filled by a pliocene sequence that comprises from floor to roof i kaoliniferous fine sands ii diatomites and lignites iii recent deposits of sandstone and clay the diatomites and lignites form a small dissimetric syncline with alternating seams ten lignite seams were identified and named from floor to roof as f e d c 2 c 1 c b a a and a seams a d e and f are considered to be the main seams the organic fraction consists mainly of macerals of the huminite group with small percentages of inertinite and liptinite groups however the petrographic composition of each seam is distinct particularly with regards to macerals of the huminite and liptinite groups calculation of petrographic indices permitted to plot the coals in facies and palaeoenvironment diagrams five facies have been defined i aquatic ii herbaceous swamp iii mixed swamp with forest and herbaceous vegetation vi forest swamp wetter and v forest swamp drier these lignites are humic coals formed from organic matter of terrestrial origin the peat biomass at the origin of these coals formed from a very diverse vegetation comprising gymnosperms and angiosperms in seams f and occasionally in seams e and d botryococcus algae have also contributed to the biomass peat deposition corresponded to a rheotrophic hydrological regime the water level always remained above the topographic surface of the basin nevertheless during the deposition of seam a in the northern part of the basin the water level was slightly below the topographic surface the organic matter was preserved in anaeorobic conditions

comparing maceral ratios from tropical peatlands with assumptions from coal studies do classic coal petrographic interpretation methods have to be discarded petrographic investigations of tropical peat deposits from the tasek bera basin malaysia show that petrographic methods can contribute valuable information about paleoecological settings of mire deposits comparing modern peat forming environments and the pre maceral composition of peat samples allows the reconstruction of paleoecological conditions such as floral composition fires microbial activity etc and gives insight into paleodepositional environments in the past maceral ratios of coals have been used to interpret paleodepositional settings of coal deposits such a procedure assumes that coal texture and coal maceral composition are dictated solely by the depositional environment and thus different depositional environments should be clearly discriminated based on maceral ratios in the modern peat deposits of tasek bera divergent petrographic results occur in similar depositional environments hence poor correlation occurs between the petrography the degree of decomposition and the depositional environment furthermore from the time of peat deposition peat is subject to considerable alteration during subsequent diagenesis preservation of structured and strongly altered material such as inertinite gelified material or funginite is favoured and results in biased coal maceral compositions because maceral indexes in modern peat studies are of little utility in the reconstruction of paleoenvironmental settings it follows that coal maceral indexes should not be utilized in the future to interpret paleodepositional environments of coals

geoarchaeological records in temperate european river valleys quantifying the resource assessing its potential and managing its future throughout the quaternary episodes of glaciation and associated low sea level have resulted in the connection of the terrestrial landmasses of britain and mainland europe the river systems that established themselves across these newly emergent land surfaces of the coastal plain would have created important migration corridors for both animals and humans a point corroborated by the affinity of palaeolithic remains across britain and europe technological developments within the last decade have allowed these now submerged valley floors and adjacent terrestrial landscapes associated with the last cold stage and early and middle parts of the current holocene interglacial to be explored and their archaeological legacies unravelled providing geoarchaeologists with an opportunity to contribute to major cultural debates however in order to maximize knowledge it is essential that geoarchaeologists working within river valleys across both britain and the european continent are addressing similar research questions by collecting data using comparable methodologies this paper reviews the approach taken in different regions and provides a baseline assessment to allow the development of a coherent european wide framework for alluvial geoarchaeology and geoprospection particularly with respect to the holocene record

diffusion and supply rates of 10be and 230th radioisotopes in two manganese encrustations from the south china sea ages of two mn encrustations estimated by their 230th and 10be distributions are compared with k ar ages and micropaleontological datings of their nuclei to discuss possible diffusion and supply effects of the radioisotope distribution and their influence on the reliability of age determinations based on comparable results obtained by the different methods the effective diffusion coefficient of 10be can be calculated as d 1 0 10 8cm2 y this coefficient is 3 8 times smaller than the best estimates available at present in both nodules we observe lower 10be concentrations in the uppermost 2 3 mm 1 3 m y which suggests that 10be uptake has been reduced since the middle pleistocene the 2 7 fold increase of the growth rate starting 3 2 m y ago coincides with the initiation of the northern hemisphere glaciation

the impact of avulsion on groundwater level and peat formation in delta floodbasins during the middle holocene transgression in the rhine meuse delta the netherlands by redistributing water and sediment in delta plains avulsions of river branches have major environmental impacts notably in changing hydrological and peat forming conditions in floodbasins the central part of the rhine meuse delta with its extensive databases including detailed lithological data and high resolution age control offers a unique opportunity to study middle holocene avulsion impacts on floodbasin groundwater level and peat formation avulsion has caused local accelerations of rising groundwater tables to be superimposed on decelerating base level rise this is evident from comparing single site groundwater rise for multiple floodbasins in the river dominated part of the delta with regionally averaged groundwater rise reconstructions floodbasin type lacustrine versus terrestrial wetland size and openness partly through effects on discharge dispersal affect how strongly the floodbasin groundwater tables respond to avulsion diverted discharge cross sectional lithology repeatedly indicates a shift from high organic wood peat to low organic reed peat in the vicinity of the avulsed channel resulting from changes in water table regime and nutrient status avulsive impact on the floodbasin groundwater table was most pronounced during the transition from transgressive to high stand stage between ca 6000 and 4000 years ago owing to developing floodbasin compartmentalization size reduction confinement resulting from repeated avulsion by way of environmental impacts on groundwater tables and vegetation avulsions thus affect the heterogeneity of floodbasin facies 2017 the author s 2017

the organic geochemistry of coal from plant materials to coal coalification is a process that transforms plant remains under the influence of time temperature and possibly pressure to a black generally lustrous solid organic fossil fuel having a very complex chemistry although much has been learned in the past two centuries on coal chemistry we still have little knowledge of the way plant materials undergo these transformations the problem has been the existence of adequate characterization tools the advent of some new tools for structural elucidation of macromolecules has led to some revised thinking on coalification originally thought to be a process involving the full degradation of plant remains and subsequent reconstitution of these remains the general consensus today is that the process involves a selective preservation of certain resistant plant components followed by some minor reorganization of the biopolymers that survive the major components of plants do degrade and the resistant ones often constitute only a small fraction of the original mass of the plant materials this paper examines the most recent literature concerning coalification and focuses on the chemistry associated with coalification of certain recognizable plant remains that have been at the center of research activity for the past two decades thus we examine the recent knowledge of the chemistry of resistant biopolymers in extant and fossil wood cuticles resins spores and algae knowledge that has been assembled to establish the reaction pathways towards coal macromolecules

effect of relative lake level changes in mire lake system on the petrographic and floristic compositions of a coal seam in the most basin miocene czech republic abstract exposures in the bilina opencast mine provide a direct evidence that the 3 5 m thick upper bench of the main seam in the most basin passes over a distance of about a kilometre into a hundred metres thick equivalent of clastic deltaic sediments with gilbert type mouth bars and thus clearly corroborates the co existence of lacustrine delta mire system deposition of the delta and the upper bench of the main seam were affected by five short term lacustrine incursions possibly related to tectonic subsidence before final lacustrine transgression took place between the temporary lacustrine incursions delta mouth bars prograded into an extensive mire being separated only by a shallow compaction lake along mouth bars foreland however most clastics introduced from delta were caught by dense vegetation in a narrow proximal zone of mire and did not affect more distal parts of relatively dry woodland mire with water table fluctuating around the surface it is therefore characterised by low ash yield and increased resinite fusinite and inertodetrinite contents palynological data indicate that the peat forming vegetation of the upper bench of the main seam was dominated by taxodiaceae glyptostrobus athrotaxis and calamus palm accompanied by paludal species of the family pinaceae and rich undergrowth of ferns and vaccinium type ericaceae progradation of delta mouth bars to the proximity of the study section is documented by increasing proportion of allochthonous elements produced by plants colonizing the flood plain and delta plain areas nyssa taxodium parrotia ulmus pyramidalis and comptonia pinus oviformis associations in contrast during periods of temporary lacustrine transgressions the mire was replaced by open water environment which favoured deposition of clay rich coals or partings 30 of ash yield of the flooding horizons in spite of fact that delta body retreated to the basin margin and the clastics were introduced from a larger distance rare palynomorphs indicate only sparse vegetation cover of aquatic plants during this time clay content seems to be the best indicator of the water level fluctuations facies indices e g tpi and gi show only poor correlation to hydrological and floristic changes detected in the mire lake system

evolution of the intra coastal tidal range in the rhine meuse delta and flevo lagoon 5700 3000 yrs cal b c abstract the evolution of the coastal and intra coastal tidal range in the western netherlands during the period 5700 3000 yrs cal b c 6875 4400 yrs b p is considered by comparing one coastal mean high water curve and two local mean high water curves mhw with respect to three alternative relative mean sea level msl curves 1 the existing 1982 msl curve for the western and northern netherlands 2 a msl curve based on the oldest part of the 1982 msl curve and the youngest part of a recently published msl curve based on data from the east central coastal plain and 3 a hypothetical msl curve for the east central coastal area assuming crustal subsidence of 0 10 m 1000 yr relative to the 1982 msl curve with regard to coastal tidal range the first and third msl curve yield a similar result a minor increase in coastal tidal range between 5200 yrs cal b c 6200 yrs b p and 4200 yrs cal b c 5350 yrs b p the second msl curve gives an increase in coastal tidal range from an assumed value of 2 m by 5200 yrs cal b c 6200 yrs b p to ca 3 m by 4100 yrs cal b c 5300 yrs b p conflicting with existing model results intra coastal tidal damping was a widespread phenomenon and played an important role in the evolution of the coastal plain for the first and second msl curves tidal attenuation in the rhine meuse delta and the east central coastal sector begins around 5250 yrs cal b c 6275 yrs b p with the third msl curve the reduction of the tidal range starts is 500 years later the first and third msl curves result in complete tidal damping in the rhine meuse delta and the east central coastal area with the second msl curve the tidal range in the rhine meuse delta remains ca 1 3 m whereas in the east central area tidal reduction is complete in spite of these different results it is clear that the period 5300 4300 yrs cal b c ca 6375 5400 yrs b p was very important for the subsequent evolution of the west netherlands coastal plain given that a the relative msl rise slowed down from about 0 8 m 100 yr to 0 23 m 100 yr b the coastal tidal range increased possibly by as much as 1 m resulting in higher sediment input into the intra coastal area while c further landward transportation of sediment was hampered due to intra coastal tidal damping which reduced rates of local mhw rise tidal current velocities and accommodation space

the geology petrography and palynology of tertiary coals from the eureka sound group at strathcona fiord and bache peninsula ellesmere island arctic canada abstract coal seams of substantial thicknesses and lateral continuity are developed in the expedition and iceberg bay formations at strathcona fiord and in the expedition formation at bache peninsula the coals are lignite subbituminous in rank and have low to moderate sulphur and variable ash contents at strathcona fiord resources have been estimated to be in the order of 1 billion tonnes whereas at bache peninsula estimated resources are 100 million tonnes the coals at strathcona fiord are characterized by the dominance of wood derived macerals of the humotelinite group whereas at bache peninsula the coals have high amounts of detrital macerals humodetrinite and also have significant amounts of inertinite macerals pollen and spore assemblages in coals from the iceberg bay formation at strathcona fiord are dominated by taxodiaceace pollen with less and variable amounts of pinaceae pollen pteridophyte spores and angiosperm pollen the pollen and spore assemblages indicate a late paleocene early eocene age of the iceberg bay formation coals the expedition formation coals at bache peninsula have in general a somewhat less diverse pollen and spore assemblage and show a larger input of fern and sphagnum spores the pollen and spore assemblages in expedition formation coals at bache peninsula are indicative of early paleocene age the depositional environment for iceberg bay formation coals at strathcona fiord is that of a forested swamp which formed on a broad coastal plain at bache peninsula peats formed in broad valleys in which a fluviatile lacustrine environment of deposition prevailed the mires were likely less forested than at strathcona fiord as indicated by the abundance of ferns and sphagnum spores and the very low content of wood derived macerals of the humotelinite group the pollen assemblages in both expidition and iceberg bay formation coals indicate a temperate climate and moderate precipitation during peat accumulation

petrology and organic geochemistry of the lower miocene lacustrine sediments most basin eger graben czech republic abstract thirty samples of the lacustrine sediments from three localities of the most basin including coal samples were studied by petrological and organic geochemical methods the consistent results indicate the relatively stable surface development of the sediments in the environment of the holesice lom and osek members biological material with contribution of microbial activity participated in the storing which led to the formation of clayey coal in the results of the chemical composition dominated sesqui diand triterpene compounds completely different sediments of libkovice member contained low proportions of small organic particles dispersed in the sediment in the extracts of these samples prevailed hopanes perylene and sulphur after the action of microorganisms the base of the organic fraction also formed remains of terrestrial plants and liptinite macerals especially alginite liptodetrinite and bituminite that are typical for lacustrine sediments

a logging correlation scheme for the main coal seam of the north bohemian brown coal basin and the implications for the palaeogeographical development of the basin

water level changes in the flevo area central netherlands 5300 1500 bc implications for relative mean sea level rise in the western netherlands abstract the younger post 4000 cal bc part of the water level curve for the eastern flevo area central netherlands runs below the relative mean sea level msl curve for the western and northern netherlands mededelingen rijks geologische dienst 36 1 1982 93pp we investigated if this difference can be attributed to i root rejuvenation of the bulk dated basal peat samples on which the curve for the eastern flevo area is based and or ii underestimation of the water depth in which the dated peat accumulated it appears that these potential sources of error did not influence significantly the results obtained by roeleveld and gotje de holocene laagveenontwikkeling in de randzone van de nederlandse kustvlakte noordoostpolder unpublished ph d thesis vrije universiteit amsterdam 1993 pp 76 86 on the basis of new and recently published water level data from the eastern and southwestern flevo area we confirm refine and tentatively extend the water level rise reconstruction by roeleveld and gotje and establish a relative msl trend curve for the central netherlands the systematic age differences of our radiocarbon dates on various fractions of four new basal peat samples from the eastern flevo area support the interpretation by roeleveld and gotje that the younger part of the 1982 msl curve may be based on basal peat samples all from the rotterdam area that have been dated 100 200 yr too old if this interpretation is correct the fact that the relative msl curve for the central netherlands lies below the 1982 msl curve cannot be interpreted to indicate less crustal subsidence for the rhine meuse delta as predicted by geophysical modeling j quat sci 17 2002 535

microfault like structures in unconsolidated upper quaternary sediments from the madeira abyssal plain eastern north atlantic abstract the occurrence of faults with an average vertical throw of several meters has been reported earlier for sediments from the madeira and nares abyssal plains in this report we discuss the observation of microfault like structures in unconsolidated upper quaternary sediments from the madeira abyssal plain these microstructures have a throw of 2 4 mm the origin of these microfault like structures is attributed to differential compaction and dewatering

holocene sea level database for the rhine meuse delta the netherlands implications for the pre 8 2 ka sea level jump abstract this paper provides the most accurate sea level index points slips for the rhine meuse delta rmd the netherlands identified amidst a wealth of data accumulated in sixty years of research following documented protocols 106 selected radiocarbon dates from peat beds from transgressed valley floor upper estuarine and back barrier lagoonal settings were first listed individually then screened in ensemble on quantified age depth position and inshore palaeotidal setting the database contains 50 slips and 56 upper limiting data points spanning a depth range of 34 to 1 5 m the dates in the database originate from dedicated sea level research which kept surface elevation and sampling depth uncertainty small and sampling of basal peat beds was favoured keeping compaction uncertainties small too the slips cover an age range of 8 8 3 0 ka bp and are available from greater rotterdam and its near offshore for upper limiting data points the coverage extends offshore tracing the rhine palaeovalley and reaches back to 11 5 ka bp the age depth data density and spatial concentration of subsets of dates allow to perform bayesian radiocarbon calibration and to reduce temporal uncertainty by 25 for the average sample 1 age uncertainty 75 cal yr when depth position and rates of relative sea level rise rslr are used to assign sequence order between 8 0 4 5 ka bp rates of rslr gradually decreased from 9 to 1 mm yr in the millennium before rates of rslr were much higher on average 10 mm yr and marked by a sea level jump between 8 45 8 2 ka bp a two phased nature of this jump starts to be resolved with local magnitudes of 1 7 0 6 m 1 first phase and 0 2 0 2 m second phase corresponding to globally averaged jumps of 2 5 m 0 9 m for the first and 0 3 0 3 m for the second phase for the pre 9 ka bp period only offshore upper limiting data points are currently available until new offshore data are gathered trends of rslr before 9 ka bp can only be estimated fed with global insights in post glacial eustasy regional estimates regarding rates of glacio isostatic adjustments and tectonic subsidence and sedimentary geological interpretations of scattered basal peat presence

dating modern deltas progress problems and prognostics 1 abstract radiocarbon dating is the method most frequently used to date holocene deltaic sequences but less than one quarter of 14c dates are within 500 years of predicted age such dates tend to be unreliable in other words often too old and commonly inverted upsection and core sample dates obtained near deltaic plain surfaces may be as old as mid to late holocene stratigraphic irregularities result primarily from downslope reworking of upland alluvial sediment with displacement of old carbon in the sediment that accumulates in lower valleys and deltaic plains use of dates that are too old results in inaccurately calculated rates most often too low of relative sea level rise and or land subsidence more reliable timing of deltaic sediment requires a multiple method dating approach including where possible identification of associated archaeological material developing an accurate dating strategy is a critical step for implementing reliable coastal protection measures needed for the rapi

a three dimensional numerical model of sediment transport erosion and deposition within a network of channel belts floodplain and hill slope extrinsic and intrinsic controls on floodplain dynamics and alluvial architecture a three dimensional numerical model of sediment transport erosion and deposition within a network of channel belts and associated floodplain is described sediment and water supply are defined at the upstream entry point and base level is defined at the downstream edge of the model sediment and water are transported through a network of channels according to the diffusion equation and each channel has a channel belt with a width that increases in time the network of channels evolves as a result of channel bifurcation and abandonment avulsion the timing and location of channel bifurcation is controlled stochastically as a function of the cross valley slope of the floodplain adjacent to the channel belt relative to the down valley slope and of annual flood discharge a bifurcation develops into an avulsion when the discharge of one of the distributaries falls below a threshold value the floodplain aggradation rate decreases with distance from the nearest active channel belt channel belt degradation results in floodplain incision extrinsic extrabasinal allogenic and intrinsic intrabasinal autogenic controls on floodplain dynamics and alluvial architecture were modelled and sequence stratigraphy models were assessed input parameters were chosen based on data from the rhine meuse delta to examine how the model responds to extrinsic controls the model was run under conditions of changing base level and increasing sediment supply rises and falls in base level and increases in sediment supply occurred over 10 000 years rising base level caused a wave of aggradation to move up valley until aggradation occurred over the entire valley frequency of bifurcations and avulsions increased with rate of base level rise and aggradation rate channel belt width varied with water discharge and the lifespan of the channel belt wide connected channel belts and high channel deposit proportion occurred around the upstream inflow point because of their high discharge and longevity less connected smaller channel belts occurred further down valley such alluvial behaviour and architecture is also found in the rhine meuse delta during base level fall valley erosion occurred and the incised valley contained a single wide channel belt during subsequent base level rise a wave of aggradation moved up valley filling the incised valley bifurcation and avulsion sites progressively moved upstream relatively thin narrow channel belts bordered and cut into the valley fill these results differ substantially from existing sequence stratigraphy models the increase in sediment supply from upstream resulted in an alluvial fan most bifurcations and avulsions occurred at the fan apex nodal avulsion and channel belts were the widest and the thickest here giving high channel deposit proportion due to their high discharge and longevity the width and thickness of channel belts decreased down valley due to decreased discharge longevity and aggradation rate this behaviour occurs in modern alluvial fans intrinsic controls also affect floodplain dynamics and alluvial architecture variation of aggradation rate bifurcation frequency and number of coexisting channel belts occurred over periods of 500 to 2000 years compared with 10 000 years for extrinsic controls this variation is partly related to local aggradation and degradation of channel belts around bifurcation points channel belts were preferentially clustered near floodplain margins because of low floodplain aggradation rate and topography there

holocene relative sea level change isostatic subsidence and the radial viscosity structure of the mantle of northwest europe belgium the netherlands germany southern north sea abstract a comprehensive observational database of holocene relative sea level rsl index points from northwest europe belgium the netherlands northwest germany southern north sea has been compiled in order to compare and reassess the data collected from the different countries regions and by different workers on a common time depth scale rsl rise varies in magnitude and form between these regions revealing a complex pattern of differential crustal movement which cannot be solely attributed to tectonic activity it clearly contains a non linear glacio and or hydro isostatic subsidence component which is only small on the belgian coastal plain but increases significantly to a value of ca 7 5 m relative to belgium since 8 cal ka bp along the northwest german coast the subsidence is at least in part related to the post glacial collapse of the so called peripheral forebulge which developed around the fennoscandian centre of ice loading during the last glacial maximum the rsl data have been compared to geodynamic earth models in order to infer the radial viscosity structure of the earth s mantle underneath nw europe lithosphere thickness upper and lower mantle viscosity and conversely to predict rsl in regions where we have only few observational data e g in the southern north sea a very broad range of earth parameters fit the belgian rsl data suggesting that glacial isostatic adjustment gia only had a minor effect on belgian crustal dynamics during and after the last ice age in contrast a narrow range of earth parameters define the southern north sea region reflecting the greater influence of gia on these deeper older samples modelled rsl data suggest that the zone of maximum forebulge subsidence runs in a relatively narrow wnw ese trending band connecting the german federal state of lower saxony with the dogger bank area in the southern north sea identification of the effects of local scale factors such as past changes in tidal range or tectonic activity on the spatial and temporal variations of sea level index points based on model data comparisons is possible but is still complicated by the relatively large range of earth model parameters fitting each rsl curve emphasising the need for more high quality observational data

refining clamp investigations towards improving the climate leaf analysis multivariate program clamp climate leaf analysis multivariate program has been used for the past 17 years to estimate palaeoclimatic conditions the reliability and applicability of this method based on leaf physiognomic characters of fossil woody dicots has been widely discussed over the same period the present study focuses on some technical aspects of clamp mainly on its robustness in the context of the theoretical unimodal requirements of canonical correspondence analysis and introduces correction coefficients for these aspects of the statistical approach as a new way of interpreting and improving on clamp estimates this tool was tested on datasets derived from 17 european fossil floras ranging in age from the late oligocene to the pliocene additionally an objective statistical method for the selection of the best suited modern vegetation dataset from 144 site physg3br or 173 physg3ar extant biotopes is proposed

tides in the northeast atlantic considerations for modelling water depth changes abstract a two dimensional tidal model of the northeast atlantic is used to simulate the m 2 s 2 2 m 4 ms 4 and m 6 tides for present sea level and with mean water level lowered or raised by a uniform number of metres over the model area m 2 s 2 tides predict the present spring tidal range although the other constituents are needed to predict spring tides in shallow water areas the accuracy of the assumptions made in modelling is assessed the relative amplitudes of the different tidal constituents vary in a non linear manner depending on model water depth changes in the northeast atlantic tides are relatively minor for tidal simulations with water depths 30 m below to 5 m above present levels however the situation is more complicated in the shallower waters of the northwest european shelf examples are given from a number of locations results from the northeast atlantic model are used to run larger scale models of morecambe bay on the west coast of britain and the wash on the east coast the tidal changes within these embayments highlight the local nature of the variations in the amplitude of different tidal constituents and the importance of the scale at which modelling is carried out

continuous surface dwelling of manganese nodules on a hill on the madeira abyssal plain during abrupt sedimentation changes abstract the accretion rate of manganese nodules and the sedimentation rate of the underlying sediment has been studied with 10 be and 14 c on a nodule covered hill in the madeira abyssal plain the accretion rate of 3 2 0 6 mm ma for the nodules is considerably smaller than the average sedimentation rate of 12 mm ka for the last 50 100 ka the mechanism that kept the nodules at the surface in this specific environment during the last 40 ka is likely to be flotation the discovery of a large manganese covered concretion in a piston core points to a long period of sediment winnowing the 14 c analyses also seem to point to an increase in the sedimentation rate round 6500 yrs b p

improving methodology for high resolution reconstruction of sea level rise and neotectonics by paleoecological analysis and ams 14c dating of basal peats abstract sea level research in several submerging coastal regions has traditionally been based on 14 c dating of basal peats that overlie a compaction free substratum and can be related to paleo ground water levels provided that an unequivocal relationship between ground water level and sea level can be assumed this approach contains two sources of uncertainty 1 the paleoenvironmental interpretation of samples is usually based on inherently inaccurate macroscopic descriptions in the field and 2 14 c ages of bulk peat samples may be erroneous as a result of contamination due to the uncertainties in both the altitude and the age the two crucial sources of evidence necessary to arrive at accurate sea level curves sea level index points are therefore represented by considerable but typically not quantified error boxes accelerator mass spectrometry ams opens new perspectives for this type of sea level research as illustrated by a paleoecological and ams 14 c study of basal peats from a small study area in the rhine meuse delta the netherlands where previous conventional work revealed highly problematic results a detailed macrofossil analysis has two purposes 1 an inferred paleoecological succession indicates a relatively accurate level of paludification of the site and hence rise of the ground water level 2 suitable macrofossils from that specific level are then selected for ams 14 c dating in spite of very small sample sizes our results are consistent and indicate that this approach can constitute a step forward in high resolution reconstruction of sea level rise the new results further enable a revision of holocene ground water gradient lines for the rhine meuse delta a knickpoint in these gradient lines can be related to the effect of faulting this approach therefore also has considerable potential to unravel and quantify neotectonic activity in submerging coastal settings

interplay between tectonics and compaction in a rift margin lacustrine delta system miocene of the eger graben czech republic the early miocene bilina palaeodelta consists of fluvio deltaic and lacustrine clastics deposited along the south eastern margin of the extensional most basin part of the eger graben in north bohemia czech republic the bilina succession shows evidence of repeated advances of an axial deltaic system across a thick accumulation of organic material and clay in the hangingwall of an active fault exposures up to ca 4 5 km long in the bilina open cast mine help bridge the gap between seismic scale and typical outcrop scale of observation and thus allow the relationships between small scale and basin scale stratal geometries to be evaluated the bilina palaeodelta deposits include sand dominated fluvial channel fills and heterolithic sheets interpreted as delta plain strata sand dominated mouth bar wedges and heterolithic sheets of prodeltaic deposits passing distally into lacustrine clays the depositional environment is interpreted as a fluvial dominated mixed load lacustrine delta with a high degree of grain size segregation at the feeder channel mouths on the largest temporal and spatial scales variable tectonic subsidence controlled the overall advance and retreat of the delta system the medium term transgressive regressive history was probably driven by episodes of increased subsidence rate however at this temporal scale the architecture of the deltaic sequences deltaic lobes and correlative lacustrine deposits was strongly affected by i compaction of underlying peat and clay which drove lateral offset stacking of medium term sequences and ii growth of a fault propagation fold close to the active bilina fault at the smallest scale the geometries of individual mouth bars and groups of mouth bars short term sequences reflect the interaction among sediment loading compaction and growth faulting that produced high frequency relative lake level fluctuations and created local accommodation at the delta front

holocene evolution of the coast of holland abstract the holocene evolution of the coast of holland was controlled by the complex interaction of such diverse parameters as wave and tidal climate the rate of sea level rise and the morphology of the pre transgressional surface the latter in combination with the rate of sea level rise mainly determines the location of sediments sources and sinks while the hydrodynamic parameters mainly determine the rate and direction of sediment transport in the early holocene the low sea level in the shallow southern north sea strongly affected wave climate and tidal regime however the barrier and back barrier sedimentary record since 5000 14c yrs b p gives us no reason to assume major changes in these parameters since then so we conclude that breaks in barrier development are due to variations in rate of sea level rise inl combination with the morphology of the pre transgressional surface the transformation from an open tide dominated to a closed wave dominated coast which occurred in the subboreal period and the concomitant change in barrier movement from transgressive to regressive around 5000 yrs b p are the main events in the development of the coast of holland up to the middle ages the morphology of the pre transgressional surface gives a shoreline in the late atlantic which consists of two protruding headlands separated by a large tidal basin the southern headland is the alluvial plain of the rhine and the meuse the northern headland constitutes the moraines of the texel high the tidal basin in between is connected to the north sea by a large number of inlets the rate of sea level rise at that time 1 m century outran the supply of sediment to the tidal basin after 6000 yrs b p the rate of sea level rise decreased gradually whereas the rate of sediment supply remained constant this led to a gradual decrease in the tidal prisms of the inlets as the tidal basin was filled in with sediment shortly before 5000 yrs b p the first channels silted up and closed the last tidal channel disappeared around 3300 yrs b p leaving two inlets along the coast which were both connected to the river rhine the closure of the first inlets occurred at the same time as the barrier began prograding because 1 the rate of sea level rise diminished considerably 2 not all the sand supplied by longshore and cross shore transport disappeared into the tidal basin but instead could be used for barrier progradation and 3 ebb tidal deltas of the closed inlets provided major sand sources the prograding barrier sequence enclosed between the two headlands roughly forms a closed system using the relationships between tidal prism cross sectional area of inlets and volume of the ebb tidal delta and the results of modelling of longshore transport along the subboreal coast under present day wave conditions a simple sand budget for the coast of holland is given which shows that a large part of the sand now stored in the barrier sequence was obtained by cross shore transport from the north sea

petrographical and organic geochemical investigation of the oberpfalz brown coal deposit west germany abstract a detailed macro and micropetrographical investigation coupled with gc and gc ms analysis of the alkane fraction of tertiary brown coal samples from the oberpfalz region of bavaria west germany was undertaken distinctive petrographical and organic geochemical facies differences were evident in the coal seams investigated which came from two neighbouring open cast mines the lower seam was of a limnic nature while the upper seam in the neighbouring mine showed the more typical characteristics of terrestrial depositon both seams were generally characterized by high ash contents and extract yields microlayering and framboidal pyrite the predominance of texto ulminite a combined with relatively high resinite contents suggested that gymnosperms were the main peat forming plants additionally the coal extracts were characterized by the presence of the diterpane phyllocladane which made up to 60 of the alkane fraction in some samples bacterial activity in the coal swamp was marked by the presence of hopanes mainly 17a h 21 h homohopane and biodegradation of the n alkanes

vegetation differences and diagenetic changes between two bulgarian lignite deposits insights from coal petrology and biomarker composition abstract during the miocene numerous sedimentary basins formed on the territory of bulgaria as a result of the extensional tectonic settings related to the post orogenic development of the late alpine orogen in this study we review the petrographic composition and biomarker assemblage of two adjacent basins in western bulgaria i e beli breg and staniantsi basins both contain lignite formed during late miocene c 6 ma despite similar tectonic settings and depositional environments the lignite seams possess different petrographic and organic geochemical characteristics reflecting differences in the peat forming palaeo communities and facies variations the peat forming vegetation in beli breg basin was dominated by decay resistant coniferous plants as indicated by abundant fossil wood remains very good tissue preservation and a biomarker assemblage dominated by diterpenoids in contrast staniantsi lignite is poor in fossil wood and contains a significant amount of triterpenoid biomarkers suggesting the predominance of angiosperm plants in the swamp the results of the biomarker analyses are consistent with palaeobotanical and palynological data from the literature the lignite seams in both basins formed under frequently changing eh conditions as indicated by the severe degradation of the non gymnosperm tissues the low gelification index values and the variations in pristane phytane ratio probably as a result of seasonal drying of the swamps and changes of the ground water table hopanoid contents in beli breg lignite are very low and are consistent with the abundance of decay resistant vegetation in contrast bacterial activity was obviously higher in the staniantsi swamp however resulting only in slightly enhanced gelification of plant tissues the geochemical data suggest that the diagenetic changes of the organic matter were mainly governed by thermal degradation rather than bacterial activity