biomarker and carbon isotope variation in coal and fossil wood of central europe through the cenozoic abstract carbon isotope analyses of terrigenous organic matter are often used to reconstruct changes in the isotopic composition of upper ocean and atmospheric carbon reservoirs carbon isotope values from tree rings fossil wood and coal matrices have been related to climatic change e g temperature humidity via water use efficiency of land plants in this study we report on carbon isotope analyses on low rank coal deposits of the alpine realm and middle german lignite district covering the early eocene to pliocene time interval fossil wood and extracted wood cellulose from gymnosperms and angiosperms respectively are used for paleoenvironmental reconstructions the trend in 13c is parallel to the carbon isotope record obtained from benthic foraminifera because both data sets sample a common reservoir in the atmosphere the evaluation of the magnitudes of 13c variations of coal caused by environmental change requires the correction of the 13c data due to the effects of different contents of lipids in the organic matter differences in biogeochemical carbon cycling varying contributions of gymnosperms versus angiosperms to peat formation and differences in 13c of atmospheric co2 the resulting carbon isotope record of coal generally co varies with the estimated variability in mean annual temperatures during the tertiary based on paleobotanical data changes in humidity and pco2 may be responsible for deviations between the isotopic trend and the paleotemperature curve during the miocene the obtained temperature coefficient for 13c of c3 plants of about 0 3 c is in agreement with the results of previous studies

cyclic climate and vegetation change in the late miocene of western bulgaria abstract a late miocene paludal to lacustrine sequence from a carbonate basin in nw bulgaria staniantsi basin is analysed displaying up to 27 rhythmically bedded sedimentary cycles in the lower part of the sequence the cycles consist of alternating autochthonous brown coal and marls containing diverse mollusc assemblages the upper part of the sequence is characterized by alternating dark to light grey clays and calcareous silts a palynomorph record comprising 163 samples is analysed by statistical means to reconstruct vegetation changes the coexistence approach is used to calculate quantitative palaeoclimate records for 6 parameters the studied section displays hierarchical cyclicity patterns longer term cycles possibly related to eccentricity period 100 kyr are present in the palynomorph record and show climate changes of warmer wetter and cooler drier periods in combination with frequency oscillations of thermophilous elements short term cycles most probably related to precession period 21 7 kyr are expressed by alternations of brown coal and marl shell beds and show cyclic change in peat forming vegetation related to oscillations of the groundwater level as a triggering mechanism wetter warmer and drier cooler climate phases related to orbital precession are probable in addition sections sampled at high resolution display small scale climate and vegetational variability as is shown by the analysis ferns were an important component of the peat forming vegetation while outside the mire a wetland vegetation consisting of pioneers and a mixed mesophytic forest with evergreen shrubs existed an oligo to mesotrophic slightly alkaline lake became repeatedly established with a diverse mollusc fauna and a dense hydrophytic vegetation with characean meadows in the upper part of the section a spreading of herbaceous vegetation is observed also known from other contemporaneaous palynomorph records in bulgaria and surrounding areas the increase of asteraceae in the upper part of the section combined with a marked decrease in woody taxa points to an opening of habitats and a decrease in mean annual precipitation this trend is paralleled by the mollusc fauna which yields several terrestrial partly xerophilous taxa

ancient impactor components preserved and reworked in martian regolith breccia northwest africa 7034 abstract northwest africa nwa 7034 and paired stones represent unique samples of martian polymict regolith breccia multiple breccia subsamples characterized in this work confirm highly siderophile element hse re os ir ru pt pd contents that are consistently elevated e g os 9 3 18 4 ppb above indigenous martian igneous rocks mostly 187 os 188 os ratios of 0 119 0 136 record a wider variation than observed for all major chondrite types combined with the measured 187 re 188 os ratios of 0 154 0 994 the range in os isotope ratios indicates redistribution of re and os from originally chondritic components early in the history of the regolith commencing at 4 4 ga superimposed recent re mobility reflects exposure and weathering at or near the martian and terrestrial surfaces elevated os concentrations 38 0 and 92 6 ppb os superchondritic os hse ratios and 187 os 188 os of 0 1171 and 0 1197 measured for two subsamples of the breccia suggest the redistribution of impactor material at 1 5 1 9 ga possibly overlapping with a partial resetting event at 1 4 ga recorded by u pb isotope systematics in the breccia martian alteration of the originally chondritic hse host phases to form os ir rich nuggets and ni rich pyrite implies the influence of potentially impact driven hydrothermal systems multiple generations of impactor component admixture redistribution and alteration mark the formation and evolution of the martian regolith clasts and matrix of nwa 7034 and paired meteorites from the pre noachian until impact ejection to earth

present day climatic equivalents of european cenozoic climates abstract recently continental climate evolution in central europe over the last 45 ma has been reconstructed from the palaeobotanical record using a nearest living relative methodology coexistence approach ca the reconstructed climate curves document in detail the transition from almost tropical conditions in the mid eocene to a temperate climate at the pliocene pleistocene transition the observed climatic shifts are primarily expressed as non proportional changes of the different variables taken into account in the present study a published palaeoclimate data set for a total of 42 macrofloras complemented by new calculations is used as base to analyse the climatic space in which a fossil flora existed to define these spaces ca intervals calculated for 3 temperature mean annual temperature cold and warm month mean and 3 precipitation variables mean annual precipitation mean monthly precipitation of the driest and of the wettest month are combined using a global gridded climatology 10 resolution this climate space is then utilized to identify recent climate analogues with respect to the variables regarded for 18 macrofloras climatic analogue regions with respect to 6 variables are identified on the globe for 16 macrofloras analogues exist when three temperature parameters and mean annual precipitation are regarded no recent equivalents are found in 8 cases this corroborates the assumption of the temporary existence of non analogue climates in the cenozoic as shown by multivariate statistics the observed anomalies with respect to present day conditions basically refer to high winter temperatures deploying a gis the recent climate analogues can be presented as sets of grid cells for each flora that can be mapped on a globe once identified these regions can be merged with adequate thematic layers to assess additional proxy data for the palaeofloras to exemplify the procedure koeppen climate type numbers of days with ground frost as well as matthews biome classes are reconstructed the resulting koeppen types ranging from a to c are largely consistent with data previously published the ground frost record shows almost frost free conditions for the mid eocene greenhouse and for the mid miocene climatic optimum for the chattian up to 7 days with ground frost result during the late miocene cooling the number of days with ground frost significantly increased the inferred matthews biomes reveal changing patterns of evergreen and deciduous forest cover when recent climate analogues are found for a fossil flora present climate can be used to calibrate the original ca data it is shown that calibration considerably improves the resolution of the continental climate records

oxygen isotope studies of achondrites abstract oxygen isotope abundances provide a powerful tool for recognizing genetic relationships among meteorites among the differentiated achondrites three isotopic groups are recognized l snc mars 2 earth and moon and 3 hed howardites eucrites diogenites the hed group also contains the mesosiderites main group pallasites and silicates from iiiab irons the angrites may be marginally resolvable from the hed group within each of these groups internal geologic processes give rise to isotopic variations along a slope 1 2 fractionation line as is well known for terrestrial materials variations of 17o from one planet to another are inherited from the inhomogeneities in the solar nebula as illustrated by the isotopic compositions of chondrites and their constituents among the undifferentiated achondrites five isotopic groups are found 1 aubrites 2 winonaites and iab iiicd irons 3 brachinites 4 acapulcoites and lodranites and 5 ureilites the isotopic compositions of aubrites coincide with the earth and moon and also with the enstatite chondrites these bodies apparently were derived from a common reservoir the isotopic composition of which was established at the chondrule scale by nebular processes isotopic similarities between chondrites and achondrites are seen only for the following instances 1 enstatite chondrites and aubrites 2 h chondrites and he irons and 3 l or ll chondrites and iva irons the isotopic data also support the following genetic associations 1 winonaites and iab iiicd irons 2 acapulcoites and lodranites and 3 ureilites and dark inclusions of c3 chondrites an attempt to reconcile the whole planet isotopic compositions of earth mars and the eucrite parent body with mixing models of their chemical compositions failed it is not possible to satisfy both the chemical and isotopic compositions of the terrestrial planets using known primitive solar system components

the chlorine isotopic composition of martian meteorites 1 chlorine isotope composition of martian mantle and crustal reservoirs and their interactions the martian meteorites record a wide diversity of environments processes and ages much work has been done to decipher potential mantle sources for martian magmas and their interactions with crustal and surface environments chlorine isotopes provide a unique opportunity to assess interactions between martian mantle derived magmas and the crust we have measured the cl isotopic composition of 17 samples that span the range of known ages martian environments and mantle reservoirs the 37cl of the martian mantle as represented by the olivine phyric shergottites nwa 2737 chassignite and shergotty basaltic shergottite has a low value of approximately 3 8 this value is lower than that of all other planetary bodies measured thus far the martian crust as represented by regolith breccia nwa 7034 is variably enriched in the heavy isotope of cl this enrichment is reflective of preferential loss of 35cl to space most basaltic shergottites less shergotty nakhlites chassigny and allan hills 84001 lie on a continuum between the martian mantle and crust this intermediate range is explained by mechanical mixing through impact fluid interaction and assimilation fractional crystallization

the origin of water on mars abstract this paper considers the origin of water on mars in the context of a dynamical model that accounts for most of the earth s water as a product of collisions between the growing earth and planet sized embryos from the asteroid belt mars history is found to be different to explain the present mass of mars requires that it suffer essentially no giant collisions and the bulk of its growth is through addition of smaller bodies asteroids and comets from beyond 2 5 au provide the source of mars water which totals 6 27 of the earth s present ocean 1 earth ocean 1 5 10 21 kg equivalent to 600 2700 m depth on the martian surface the d h ratio of this material is 1 2 1 6 times standard mean ocean water the smaller value obtaining for the larger amount of water accreted the upper half of the range of total water accreted while many times less than that acquired by the earth is consistent with geological data on mars and the d h value is that derived for martian magmatic water from snc meteorites both together are consistent with published interpretations of the high d h in present day martian atmospheric water in terms of water loss through atmospheric escape

mineralogical constraints on the thermal history of martian regolith breccia northwest africa 8114 abstract martian meteorite northwest africa nwa 8114 a paired stone to nwa 7034 provides an opportunity to examine the thermal history of a martian regolith and study near surface processes and ancient environmental conditions near an impact crater on mars our study reports petrographic and alteration textures and focuses on pyroxene and iron oxide grains some of the pyroxene clasts show exsolution lamellae indicating a high temperature magmatic origin and slow cooling however transmission electron microscopy reveals that other predominantly pyroxene clasts are porous and have partially re crystallised to form magnetite and a k bearing feldspathic glassy material together with relict pyroxene this breakdown event was associated with oxidation with up to 25 fe3 fe in the relict pyroxene measured using fe k xanes by comparison with previous studies this breakdown and oxidation of pyroxene is most likely to be a result of impact shock heating being held at a temperature above 700 c for at least 7 days in an oxidising regolith environment we report an approximate 40ar 39ar maximum age of 1 13 1 25 ga for an individual separated augite clast the disturbed nature of the spectra precludes precise age determination in section this clast is porous and contains iron oxide grains this shows that it has undergone the high temperature partial breakdown seen in other relict pyroxene clasts and has up to 25 fe3 fe we infer that the age corresponds to the impact shock heating event that led to the high temperature breakdown of many of the pyroxenes after consolidation of the impact ejecta blanket high temperatures above 700 c may have been maintained for long enough to remobilise and congruently partially melt some of the alkali feldspar clasts to produce the feldspar veins and aureoles that crosscut and in some cases surround the oxidised pyroxene however the veins could alternatively be the result of a hydrothermal event in the impact regolith a simple fourier cooling model suggests that a regolith of at least five metres depth would be sufficient to maintain temperatures associated with the pyroxene breakdown for over seven days low temperature hydrous alteration took place forming goethite identified via xrd xanes and ftir comparing with previous studies the goethite is likely to be terrestrial alteration pseudomorphing martian pyrite

rb sr and sm nd isotopic and ree studies of igneous components in the bulk matrix domain of martian breccia northwest africa 7034 the bulk matrix domain of the martian breccia nwa 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia both 147sm 143nd and 146sm 142nd age results for mineral separates from the bulk matrix portion of breccia nwa 7034 suggest that various lithological components in the breccia probably formed contemporaneously 4 44 ga ago this old age is in excellent agreement with the upper intersection ages 4 35 4 45 ga for u pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous textured clasts consequently we confirm an ancient age for the igneous components that make up the nwa 7034 breccia substantial disturbance in the rb sr system was detected and no age significance could be gleaned from our rb sr data the disturbance to the rb sr system may be due to a thermal event recorded by bulk rock k ar ages of 1 56 ga and u pb ages of phosphates at about 1 35 1 5 ga which suggest partial resetting from an unknown thermal event s possibly accompanying breccia formation the nwa 7034 bulk rock is lree enriched and similar to kreep rich lunar rocks which indicates that the earliest martian crust was geochemically enriched this enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on mars that have been detected in studies of other martian meteorites

geochemical appraisal of palaeovegetation and climate oscillation in the late miocene of western bulgaria abstract palaeobotanical methods and geochemical techniques were used to assess plant contribution and palaeoenvironment for the staniantsi basin bulgaria the aim was to connect palaeovegetation change and climate oscillation based on pollen and statistical analysis with organic geochemical proxies for a late miocene lacustrine to paludial sedimentary succession three samples from lignite marl cycles were studied the biomarker assemblage and bulk chemical data indicated that gymnosperms were not important in the palaeomire the presence of des a triterpenoids 17 21 seco triterpenoids hopanes a high content of a d ring monoaromatic hopane and aromatized triterpenoids suggested that photochemical and microbial processes significantly contributed to the alteration of the organic matter om a prolonged period of high water table and severe mechanical destruction promoted microbial activity prior to burial and enhanced decay a geochemical appraisal of short term climate oscillation ca 21 7 kyr was attempted within the limitations of the small number of samples studied the cycles are expressed as lignite marl clay layers combined with cyclic changes in swamp vegetation related to cyclic changes in groundwater level and inundation of the basin in periods of low water level swamp phase lignite accumulation took place preliminary results for selected samples suggest that the oscillation may be reflected in the content of friedelin vs possible degradation products the ratio of a chromatographic peak tentatively assigned as a norfriedel 8 en 10 one to friedelin is proposed as a means of detecting short term environmental cycles where values 1 reflect periods of inundation however time series analysis using densely sampled lignite clay layer oscillations are needed to confirm the value of this biomarker ratio for environmental reconstruction

the northwest africa 8159 martian meteorite expanding the martian sample suite to the early amazonian abstract northwest africa nwa 8159 is an augite rich shergottite with a mineralogy dominated by ca fe rich pyroxene plagioclase olivine and magnetite nwa 8159 crystallized from an evolved melt of basaltic composition under relatively rapid conditions of cooling likely in a surface lava flow or shallow sill redox conditions experienced by the melt shifted from relatively oxidizing with respect to known martian lithologies qfm on the liquidus to higher oxygen fugacity qfm 2 during crystallization of the groundmass and under subsolidus conditions this shift resulted in the production of orthopyroxene and magnetite replacing olivine phenocryst rims nwa 8159 contains both crystalline and shock amorphized plagioclase an50 62 often observed within a single grain based on known calibrations we bracket the peak shock pressure experienced by nwa 8159 to between 15 and 23 gpa the bulk composition of nwa 8159 is depleted in lree as observed for tissint and other depleted shergottites however nwa 8159 is distinct from all other martian lithologies in its bulk composition and oxygen fugacity we obtain a sm nd formation age of 2 37 0 25 ga for nwa 8159 which represents an interval in mars geologic time which until recently was not represented in the other martian meteorite types the bulk rock 147sm 144nd value of 0 37 0 02 is consistent with it being derived directly from its source and the high initial e143nd value indicates this source was geochemically highly depleted cr nd and w isotopic compositions further support a unique mantle source while the rock shares similarities with the 2 4 ga nwa 7635 meteorite there are notable distinctions between the two meteorites that suggest differences in mantle source compositions and conditions of crystallization nevertheless the two samples may be launch paired nwa 8159 expands the known basalt types ages and mantle sources within the mars sample suite to include a second igneous unit from the early amazonian

palynological evidence for miocene climate change in the forecarpathian basin central paratethys nw bulgaria abstract we reconstruct quantitatively the middle to upper miocene climate evolution in the southern forecarpathian basin central paratethys area northwest bulgaria by applying the coexistence approach to 101 well dated palynofloras isolated from three cores the climatic evolution is compared with changes in vegetation and palaeogeography the middle miocene was a period of a subtropical warm temperate humid climate with mean annual temperature mat between 16 and 18 c and mean annual precipitation map between 1100 and 1300 mm thereby during the entire middle miocene a trend of slightly decreasing temperatures is observed and only small climate fluctuations occur which are presumably related to palaeogeographic reorganisations the vegetation shows a corresponding trend with a decrease in abundance of palaeotropic and thermophilous elements the upper miocene is characterised by more diverse climatic conditions probably depending on palaeogeographic and global climatic transformations the beginning of this period is marked by a slight cooling and a significant drying of the climate with mat 13 3 17 c and map 652 759 mm after that fluctuations of all palaeoclimate parameters occur displaying cycles of humid dryer and warmer cooler conditions which are again well reflected in the vegetation our study provides a first quantitative model of the middle upper miocene palaeoclimate evolution in southeastern europe and is characterised by a relatively high precision and resolution with respect to the climate data and stratigraphy

a colossal impact enriched mars mantle with noble metals once the terrestrial planets had mostly completed their assembly bombardment continued by planetesimals left over from accretion highly siderophile element hse abundances in mars mantle imply that its late accretion supplement was 0 8 wt earth and the moon obtained an additional 0 7 wt and 0 02 wt respectively the disproportionately high earth moon accretion ratio is explicable by stochastic addition of a few remaining ceres sized bodies that preferentially targeted earth here we show that mars late accretion budget also requires a colossal impact a plausible visible remnant of which is the emispheric dichotomy the addition of sufficient hses to the martian mantle entails an impactor of at least 1200 km in diameter to have struck mars before 4430 ma by which time crust formation was well underway thus the dichotomy could be one of the oldest geophysical features of the martian crust ejected debris could be the source material for its satellites

meteorite constraints on martian atmospheric loss and paleoclimate abstract the evolution of mars atmosphere to its currently thin state incapable of supporting liquid water remains poorly understood and has important implications for martian climate history martian meteorites contain trapped atmospheric gases that can be used to constrain both the timing and effectiveness of atmospheric escape processes in this paper measurements of xenon isotopes in two ancient martian meteorites alh 84001 and nwa 7034 are reported the data indicate an early episode of atmospheric escape that mass fractionated xenon isotopes culminated within a few hundred million years of planetary formation and little change to the atmospheric xenon isotopic composition has occurred since this time in contrast on earth atmospheric xenon fractionation continued for at least two billion years pujol et al 2011 such differences in atmospheric xe fractionation between the two planets suggest that climate conditions on mars may have differed significantly from those on archean earth for example the hydrogen escape flux may not have exceeded the threshold required for xenon escape on mars after 4 2 4 3 ga which indicates that mars may have been significantly drier than earth after this time

oxygen isotopic record of silicate alteration in the shergotty nakhla chassigny meteorite lafayette samples from a suite of shergotty nakhla chassigny snc meteorites were analyzed for their o isotopic ratios by a modified version of the laser fluorination technique measured isotopic ratios 17o 16o and 18o 16o from bulk samples of the shergottites eeta79001 shergotty and zagami the nakhlite lafayette and chassigny are similar to those reported in the literature as are those from olivine and pyroxene mineral separates from lafayette iddingsite a preterrestrial alteration product of lafayette was measured for the first time as a separate phase oxygen isotopic ratios increase with the percentage of iddingsite in a sample to a maximum 18o of 14 4 for a 90 separate based on these measurements end member iddingsite has a 18o of 15 6 which places it among other 18o enriched secondary phases carbonate and silica observed in snc meteorites the relatively large difference in 18o between iddingsite and the olivine and pyroxene it replaces 11 is typical of low temperature alteration products a range of crustal fluid 18o values can be interpreted from the 18o for end member iddingsite assuming isotopic equilibrium was achieved during low temperature hydrous alteration 100 c treiman et al 1993 the calculated range of values 15 to 5 depends on many factors including 1 the modal mineralogy of iddingsite 2 potential isotopic exchange among other o bearing phases such as host silicate and carbonate and 3 exchange with evolved or exotic o reservoirs on mars despite the lack of constraints the calculated range is consistent with isotopic exchange and possibly equilibria among components of the co2 carbonate iddingsite h2o system at low temperature the snc meteorite samples in this study have 17o values that are indistinguishable from bulk mars 0 30 except for a single small sample of iddingsite that has an anomalous 17o of 1 4 while analytical difficulties make isotopic measurements for this sample problematic the 17o is similar in direction to 17o reported for waters extracted from bulk samples of lafayette karlsson et al 1992 if the 17o for iddingsite is confirmed it can be concluded that evolved or exotic fluids on mars have contributed volatiles to the o reservoir from which iddingsite formed 130 to 700 ma ago

first detection of fluorine on mars implications for gale crater s geochemistry volatiles and especially halogens f and cl have been recognized as important species in the genesis and melting of planetary magmas data from the chemical camera instrument on board the mars science laboratory rover curiosity now provide the first in situ analyses of fluorine at the surface of mars two principal f bearing mineral assemblages are identified the first is associated with high aluminum and low calcium contents in which the f bearing phase is an aluminosilicate it is found in conglomerates and may indicate petrologically evolved sources this is the first time that such a petrologic environment is found on mars the second is represented by samples that have high calcium contents in which the main f bearing minerals are likely to be fluorapatites and or fluorites fluorapatites are found in some sandstone and may be detrital while fluorites are also found in the conglomerates possibly indicating low t alteration processes

water in snc meteorites evidence for a martian hydrosphere the shergotty nakhla chassigny snc meteorites purportedly of martian origin contain 0 04 to 0 4 percent water by weight oxygen isotopic analysis can be used to determine whether this water is extraterrestrial or terrestrial such analysis reveals that a portion of the water is extraterrestrial and furthermore was not in oxygen isotopic equilibrium with the host rock lack of equilibrium between water and host rock implies that the lithosphere and hydrosphere of the snc parent body formed two distinct oxygen isotopic reservoirs if mars was the parent body the maintenance of two distinct reservoirs may result from the absence of plate tectonics on the planet

nickeliferous pyrite tracks pervasive hydrothermal alteration in martian regolith breccia a study in nwa 7533 martian regolith breccia nwa 7533 and the seven paired samples is unique among martian meteorites in showing accessory pyrite up to 1 by weight pyrite is a late mineral crystallized after the final assembly of the breccia it is present in all of the lithologies i e the fine grained matrix icm clast laden impact melt rocks climr melt spherules microbasalts lithic clasts and mineral clasts all lacking magmatic sulfides due to degassing pyrite crystals show combinations of cubes truncated cubes and octahedra polycrystalline clusters can reach 200 lm in maximum dimensions regardless of their shape pyrite crystals display evidence of very weak shock metamorphism such as planar features fracture networks and disruption into subgrains the late fracture systems acted as preferential pathways for partial replacement of pyrite by iron oxyhydroxides interpreted as resulting from hot desert terrestrial alteration the distribution and shape of pyrite crystals argue for growth at moderate to low growth rate from just saturated near neutral 6 fmq 2 log units it is inferred from the maximum ni contents 4 5 wt that pyrite started crystallizing at 400 500 c during or shortly after a short duration relatively low temperature thermal event that lithified and sintered the regolith breccias 1 4 ga ago as deduced from disturbance in several isotope systematics

the internal structure and geodynamics of mars inferred from a 4 2 gyr zircon record combining u pb ages with lu hf data in zircon provides insights into the magmatic history of rocky planets the northwest africa nwa 7034 7533 meteorites are samples of the southern highlands of mars containing zircon with ages as old as 4476 3 0 9 ma interpreted to reflect reworking of the primordial martian crust by impacts we extracted a statistically significant zircon population n 57 from nwa 7533 that defines a temporal record spanning 4 2 gyr ancient zircons record ages from 4485 5 2 2 ma to 4331 0 1 4 ma defining a bimodal distribution with groupings at 4474 10 ma and 4442 17 ma we interpret these to represent intense bombardment episodes at the planet s surface possibly triggered by the early migration of gas giant planets the unradiogenic initial hf isotope composition of these zircons establishes that mars s igneous activity prior to 4 3 ga was limited to impact related reworking of a chemically enriched primordial crust a group of younger detrital zircons record ages from 1548 0 8 8 ma to 299 5 0 6 ma the only plausible sources for these grains are the temporally associated elysium and tharsis volcanic provinces that are the expressions of deep seated mantle plumes the chondritic like hf isotope compositions of these zircons require the existence of a primitive and convecting mantle reservoir indicating that mars has been in a stagnant lid tectonic regime for most of its history our results imply that zircon is ubiquitous on the martian surface providing a faithful record of the planet s magmatic history

chalcophile siderophile element systematics of hydrothermal pyrite from martian regolith breccia nwa 7533 unlike other martian meteorites studied so far martian regolith breccia nwa 7533 and 56 paired meteorites that have sampled 4 4 ga old impact lithologies show only sulfides of 57 hydrothermal origin mostly pyrite 1 the reasonably good positive correlation r 2 0 72 between se and 65 ni reflects a temperature control on the solubility of both elements apart from the chalcogens s se 66 and te pyrite appears to be a minor contributor 400 c temperature crystallization for nwa 7533 pyrite as deduced from 69 its se and ni contents ii magmatic sulfide depletion of brecciated early martian crust iii 70 precipitation from near neutral h 2 s hs h 2 o rich hydrothermal fluids that did not provide halogen 71 ligands for extensive transport of chalcophile siderophile metals it is suggested that the 1 4 ga 72 lithification event that precipitated hydrothermal pyrite left the chalcophile siderophile element 73 budget of the early martian crust nearly unmodified except for s se and te 74 75 76

polar aromatic biomarkers in the miocene maritza east lignite bulgaria aromatic and polar compounds of lignite lithotype bitumens maritza east were analyzed diterpenoid phenols and ketophenols i e mainly ferruginol sugiol hinokione and products of their diagenetic transformations were identified as the dominant biomarkers a variety of sesquiterpenoids was present as well these compounds provided evidence for the assumption that members of the cupressaceae s 1 are the coal precursors polar triterpenoids i e lupeol lupenone adiantone and hopanones were present in subordinate quantities in the humoclarain sample these biomarkers support an input of deciduous angiosperm vegetation to the peat swamp source matter three diagenetic transformation schemes for the diterpenoid phenols ketophenols are proposed 1 ferruginol and or sugiol alteration through dehydrogenation demethylation and ring b cleavage 2 hinokione aromatization to simonellite and 3 7 ketototarol change through 7 ketototar 5 enol to 20 nor 3 oxo totara 5 10 6 dienol the identified diterpenoids demonstrated the presence of gymnospermae in the coal forming community furthermore the phenolic diterpenoids indicated a specific input of organic matter from conifers of the cupressaceae taxodiaceae or podocarpaceae as the most abundant trees in the coal forming swamp

the biogeochemistry of ellesmere lake u k i source correlation of leaf wax inputs to the sedimentary lipid record abstract analyses of the free lipid distributions from ellesmere lake sediments taken from two depths and comparison with leaf wax lipid distributions from six deciduous tree species around the lake were made in order to assess lipid sources close correlations of aliphatic lipid distributions in the carbon number range c 20 c 50 were seen c 28 and c 29 sterols were observed in both sediment and leaf waxes but c 27 sterols were only present in the sediments and were thus assigned a nonleaf wax source unsaturated steroidal ketones were observed both in the sediment and in certain leaf waxes and were assigned specific sources alkan 2 ones were not present in the leaf waxes but were present in the sediment samples with an almost identical distribution to the sediment n alkanes indicating a microbially mediated source c 20 c 30 n aldehydes which have not previously been widely reported in free lipid distributions of freshwater lacustrine sediments were prominent in the surface sediment and in the leaf waxes examined

unique meteorite from early amazonian mars water rich basaltic breccia northwest africa 7034 we report data on the martian meteorite northwest africa nwa 7034 which shares some petrologic and geochemical characteristics with known martian meteorites of the snc i e shergottite nakhlite and chassignite group but also has some unique characteristics that would exclude it from that group nwa 7034 is a geochemically enriched crustal rock compositionally similar to basalts and average martian crust measured by recent rover and orbiter missions it formed 2 089 0 081 billion years ago during the early amazonian epoch in mars9 geologic history nwa 7034 has an order of magnitude more indigenous water than most snc meteorites with up to 6000 parts per million extraterrestrial h2o released during stepped heating it also has bulk oxygen isotope values of 17o 0 58 0 05 per mil and a heat released water oxygen isotope average value of 17o 0 330 0 011 per mil suggesting the existence of multiple oxygen reservoirs on mars

a method for climatic reconstruction of the mediterranean pliocene using pollen data pollen data from numerous sites around the mediterranean sea indicate that several important vegetation and climatic changes occurred during the pliocene these data are in good agreement with pollen records from northwest europe and with 18o curves from mediterranean and atlantic deep sea cores quantitative palaeoclimatic reconstructions from pliocene pollen data of the mediterranean region cannot be based on conventional modern analogue techniques as individual pliocene pollen spectra contain taxa representing temperate warm temperate and subtropical plants that do not grow together today instead we propose a new method that uses a climatic amplitude method modified to take partially into account the relative abundances of the taxa we applied this method to the pliocene garraf 1 palynological sequence from catalonia which provides a long continuous record of climatic change from 5 3 ma to the early pleistocene we estimate that annual temperatures were 1 to 5 c higher than today and the annual precipitation 400 to 1000 mm higher than today prior to the beginning of the late cenozoic glacial interglacial cycles in contrast temperature and precipitation both fell sharply during the glacial phases of the earliest glacial interglacial cycles

geologic history of martian regolith breccia northwest africa 7034 evidence for hydrothermal activity and lithologic diversity in the martian crust the timing and mode of deposition for martian regolith breccia northwest africa nwa 7034 were determined by combining petrography shape analysis and thermochronology nwa 7034 is composed of igneous impact and brecciated clasts within a thermally annealed submicron matrix of pulverized crustal rocks and devitrified impact volcanic glass the brecciated clasts are likely lithified portions of martian regolith with some evidence of past hydrothermal activity represented lithologies are primarily ancient crustal materials with crystallization ages as old as 4 4 ga one ancient zircon was hosted by an alkali rich basalt clast confirming that alkalic volcanism occurred on mars very early nwa 7034 is composed of fragmented particles that do not exhibit evidence of having undergone bed load transport by wind or water the clast size distribution is similar to terrestrial pyroclastic deposits we infer that the clasts were deposited by atmospheric rainout subsequent to a pyroclastic eruption s and or impact event s although the ancient ages of igneous components favor mobilization by impact s despite ancient components the breccia has undergone a single pervasive thermal event at 500 800 c evident by groundmass texture and concordance of 1 5 ga dates for bulk rock k ar u pb in apatite and u pb in metamict zircons the 1 5 ga age is likely a thermal event that coincides with rainout breccia lithification we infer that the episodic process of regolith lithification dominated sedimentary processes during the amazonian epoch the absence of pre amazonian high temperature metamorphic events recorded in ancient zircons indicates source domains of static southern highland crust punctuated by episodic impact modification

oleananes in oils and sediments evidence of marine influence during early diagenesis abstract the oleananes as markers for the angiosperms provide valuable source and age information when present in an oil nevertheless they are not quantitatively related to the land plant input and indeed their presence reflects only a small leak in diagenetic processes leading primarily to aromatic oleanoids because they are minor products the abundance of oleananes in terrigenous oils and sediments may be highly sensitive to changes in early diagenetic conditions here we present evidence that contact of plant matter with seawater during early diagenesis enhances the expression of oleananes in a mature sediment or oil oleananes are absent or present at very low concentrations in samples from the base of an eocene coal seam affected by postdepositional seawater intrusion however their abundance increases toward the top of the seam in correlation with organic sulphur dibenzothiophene phenanthrene and the homohopane index similarly in deltaic sediments from the south sumatra basin oleanane hopane is strongly correlated with indicators of marine influence such as c 27 c 29 steranes and the homohopane index in each case increasing oleanane abundance is accompanied by a reduction in the extent of aromatisation and for the south sumatra basin the proportion of a ring contracted oleananes an angiosperm derived miocene coal from the philippines deposited under freshwater conditions shows abundant aromatic oleanoids but no oleananes these results show that oleananes need to be used with caution as age and source markers in fluvio deltaic and lacustrine petroleum systems on the other hand their sensitivity to early diagenetic conditions may make them useful in locating effective source rocks in such systems

exsolution and shock microstructures of igneous pyroxene clasts in the northwest africa 7533 martian meteorite northwest africa nwa 7533 is a martian regolith breccia this meteorite and its pairings offers a good opportunity to study near surface processes that occurred on early mars here we have conducted a transmission electron microscope study of medium and coarse grained a few tens to hundreds of micrometers ca rich pyroxene clasts in order to define their thermal and shock histories the pyroxene grains have a high temperature magmatic origin as revealed by the well developed pigeonite augite exsolution microstructure exsolution lamella characteristics composition thickness and spacing indicate a moderately slow cooling some of the pyroxene clasts display evidence for local decomposition into magnetite and silica at the submicron scale this phase decomposition may have occurred at high temperature and occurred at high oxygen fugacity at least 2 3 log units above the qfm buffer after the formation of the exsolution lamellae this corresponds to oxidizing conditions well above typical martian magmatic conditions these oxidizing conditions seem to have prevailed early and throughout most of the history of nwa 7533 the shock microstructure consists of 100 mechanical twins which have accommodated plastic deformation other pyroxene shock indicators are absent compared with snc meteorites that all suffered significant shock metamorphism nwa 7533 appears only mildly shocked the twin microstructure is similar from one clast to another suggesting that the impact which generated the 100 twins involved the compacted breccia and that the pyroxene clasts were unshocked when they were incorporated into the nwa 7533 breccia

heterogeneous distribution of h2o in the martian interior implications for the abundance of h2o in depleted and enriched mantle sources we conducted a petrologic study of apatite within 12 martian meteorites including 11 shergottites and one basaltic regolith breccia these data were combined with previously published data to gain a better understanding of the abundance and distribution of volatiles in the martian interior apatites in individual martian meteorites span a wide range of compositions indicating they did not form by equilibrium crystallization in fact the intrasample variation in apatite is best described by either fractional crystallization or crustal contamination with a cl rich crustal component we determined that most martian meteorites investigated here have been affected by crustal contamination and hence cannot be used to estimate volatile abundances of the martian mantle using the subset of samples that did not exhibit crustal contamination we determined that the enriched shergottite source has 36 73 ppm h2o and the depleted source has 14 23 ppm h2o this result is consistent with other observed geochemical differences between enriched and depleted shergottites and supports the idea that there are at least two geochemically distinct reservoirs in the martian mantle we also estimated the h2o cl and f content of the martian crust using known crust mantle distributions for incompatible lithophile elements we determined that the bulk martian crust has 1410 ppm h2o 450 ppm cl and 106 ppm f and cl and h2o are preferentially distributed toward the martian surface the estimate of crustal h2o results in a global equivalent surface layer gel of 229 m which can account for at least some of the surface features on mars attributed to flowing water and may be sufficient to support the past presence of a shallow sea on mars surface

aliphatic and aromatic triterpenoid hydrocarbons in a tertiary angiospermous lignite abstract the hydrocarbon biomarker assemlage of a liptinite rich early tertiary angiospermous lignite has been characterized the biomarker fistribution for the lignite confirms the low maturity and previous paleobotanic interpretations the aliphatic hydrocarbon fraction consists predominantly of n alkanes showing a strong odd carbon predominance and numerous de a triterpenoids and triterpenoids derived from higher plants bacterially derived triterpenoids were represented primarily by homohopanes and hopenes the aromatic hydrocarbon fraction contains a series of mono di and triaromatic de a triterpenoids and mono tri and tetraaromatic triterpenoids derived from higher plants the concentration and abundance of monoaromatic triterpenoids containing one to three additonal degress of unsaturation have not seen previously observed in a single deposit as such a diagenetic scheme for angiosperm derived triterpenoids is presented which confirms and extends previous hypothesis

palaeoenvironment assessment of pliocene lom lignite bulgaria from bitumen analysis and preparative off line thermochemolysis abstract the dacian coal bearing province is located in nw bulgaria coal formation is thought to be connected with desiccation of the dacian basin during a prolonged regression in the late pontian and pliocene dacian romanian age a lom lignite sample was characterized via micropetrography bulk chemical analysis spectral methods and thermochemolysis the pollen record was poor suggesting coal formation under oxygen rich conditions during peatification straight chain alkanes alkan 2 ones alkanols des a triterpenoids aromatized triterpenoids aromatized hopane hopene hopanes and triterpenoids with a strong dominance of oleanane derived structures were present in the extracted bitumen the residue after extraction was subjected to preparative off line tetramethylammonium hydroxide tmah thermochemolysis the aliphatic products released were c22 c27 fatty acid fa methyl esters i e methoxymethyl esters c22 c28 even numbered diacids dimethyl esters with a smooth distribution and traces of i and ai c15 acid methyl esters trapped and bound fas were distinguished using tetraethylammonium acetate teaac treatment the main thermochemolysis products were phenols structurally related to lignin vanillyl and syringyl units were produced in similar amounts indicating nonwoody angiosperm vegetation as the main plant input to the palaeo swamp probably originating from marsh or grassland sources the bitumen provided unequivocal information for an angiosperm contribution to the mire while the results of the tmah pyrolysis revealed a concomitant angiosperm and gymnosperm input the biomarker assemblage makes the lom lignite unique in bulgaria all the other bulgarian neogene lignites being dominated by coniferous vegetation with only traces of angiosperm contributions

the age of the carbonates in martian meteorite alh84001 the age of secondary carbonate mineralization in the martian meteorite alh84001 was determined to be 3 90 0 04 billion years by rubidium strontium rb sr dating and 4 04 0 10 billion years by lead lead pb pb dating the rb sr and pb pb isochrons are defined by leachates of a mixture of high graded carbonate visually estimated as approximately 5 percent whitlockite trace and orthopyroxene approximately 95 percent the carbonate formation age is contemporaneous with a period in martian history when the surface is thought to have had flowing water but also was undergoing heavy bombardment by meteorites therefore this age does not distinguish between aqueous and impact origins for the carbonates

oxygen cycle of the martian atmosphere regolith system δ17o of secondary phases in nakhla and lafayette oxygen isotope fractionations among silicates carbonates and sulfate from nakhla and lafayette can be used to resolve how multiple oxygen isotope reservoirs formed and evolved on mars and to gain insight into the environment and processes that led to the formation of the snc carbonates and other secondary minerals carbonates and sulfate from nakhla and lafayette carry an imprint of atmospheric chemistry analogous to that documented on earth but reflect an inhospitable environment where ozone hydrogen peroxide and odd oxygen compounds transferred their signature of atmospheric oxygen isotope fractionations to water ice and minerals that formed in the regolith at low temperature such an environment would not be conducive to the preservation of easily oxidized organic compounds its existence provides an abiotic isotopic benchmark biotic processes should produce isotopic fractionations that lie on a coherent mass fractionation line and not the mass independent fractionation relationships observed in the present study

regolith breccia northwest africa 7533 mineralogy and petrology with implications for early mars northwest africa 7533 a polymict martian breccia consists of fine grained clast laden melt particles and microcrystalline matrix while both melt and matrix contain medium grained noritic monzonitic material and crystal clasts the matrix also contains lithic clasts with zoned pigeonite and augite plus two feldspars microbasaltic clasts vitrophyric and microcrystalline spherules and shards the clast laden melt rocks contain clump like aggregates of orthopyroxene surrounded by aureoles of plagioclase some shards of vesicular melt rocks resemble the pyroxene plagioclase clump aureole structures submicron size matrix grains show some triple junctions but most are irregular with high intergranular porosity the noritic monzonitic rocks contain exsolved pyroxenes and perthitic intergrowths and cooled more slowly than rocks with zoned pyroxene or fine grain size noritic material contains orthopyroxene or inverted pigeonite augite calcic to intermediate plagioclase and chromite to cr bearing magnetite monzonitic clasts contain augite sodic plagioclase k feldspar ti bearing magnetite ilmenite chlorapatite and zircon these feldspathic rocks show similarities to some rocks at gale crater like black trout mara and jake m the most magnesian orthopyroxene clasts are close to alh 84001 orthopyroxene in composition all these materials are enriched in siderophile elements indicating impact melting and incorporation of a projectile component except for ni poor pyroxene clasts which are from pristine rocks clast laden melt rocks spherules shards and siderophile element contents indicate formation of nwa 7533 as a regolith breccia the zircons mainly derived from monzonitic melt rocks crystallized at 4 43 0 03 ga humayun et al 2013 and a 147sm 143nd isochron for nwa 7034 yielding 4 42 0 07 ga nyquist et al 2016 defines the crystallization age of all its igneous portions the zircon from the monzonitic rocks has a higher 17o than other martian meteorites explained in part by assimilation of regolith materials enriched during surface alteration nemchin et al 2014 this record of protolith interaction with atmosphere hydrosphere during regolith formation before melting demonstrates a thin atmosphere a wet early surface environment on mars and an evolved crust likely to have contaminated younger extrusive rocks the latest events recorded when the breccia was on mars are resetting of apatite much feldspar and some zircons at 1 35 1 4 ga bellucci et al 2015 and formation of ni bearing pyrite veins during or shortly after this disturbance lorand et al 2015

ancient geologic events on mars revealed by zircons and apatites from the martian regolith breccia nwa 7034

rare earth element minerals in martian breccia meteorites nwa 7034 and 7533 implications for fluid rock interaction in the martian crust paired martian breccia meteorites northwest africa nwa 7034 and 7533 are the first martian rocks found to contain rare earth element ree phosphates and silicates the most common occurrence is as clusters of anhedral monazite ce inclusions in apatite occasionally zoned irregular merrillite inclusions are also present in apatite monazite bearing apatite is sometimes associated with alkali feldspar and fe oxide apatite near merrillite and monazite generally contains more f and oh f rich region than the main chlorapatite host and forms irregular boundaries with the main host locally the composition of f rich regions can reach pure fluorapatite the chlorapatite hosts are similar in composition to isolated apatite without monazite inclusions and to euhedral apatite in lithic clasts the u th total pb ages of monazite in three apatite are 1 0 0 4ga 2 1 1 0 5ga 2 and 2 8 0 7ga 2 confirming a martian origin the texture and composition of monazite inclusions are mostly consistent with their formation by the dissolution of apatite and or merrillite by fluid at elevated temperatures 100 c in nwa 7034 we observed a monazite chevkinite perrierite bearing benmoreite or trachyandesite clast anhedral monazite and chevkinite perrierite grains occur in a matrix of sub micrometer ree phases and silicates inside the clast monazite ce and nd and chevkinite perrierite ce and nd display unusual la and ce depletion relative to sm and nd in addition one xenotime y bearing pyrite ilmenite zircon clast with small amounts of feldspar and augite occurs in nwa 7034 one xenotime crystal was observed at the edge of an altered zircon grain and a cluster of xenotime crystals resides in a mixture of alteration materials pyrite ilmenite and zircon in this clast are all highly altered zircon being the most likely source of y and hree now present in xenotime the association of xenotime with zircon low u and th contents and the low yb content relative to gd and dy in xenotime suggest the possible formation of xenotime as a byproduct of fluid zircon reactions on the basis of relatively fresh apatite grains and lithic clasts in the same samples we propose that the fluid rock mineral reactions occurred in the source rocks before their inclusion in nwa 7034 and 7533 additionally monazite bearing apatite and ree mineral bearing clasts are possibly derived from different crustal origins thus our results imply the wide occurrence of hydrothermal fluids in the martian crust at 1 ga or older which were probably induced by impacts or large igneous intrusions

influence of floral assemblage facies and diagenesis on petrography and organic geochemistry of the eocene bourgas coal and the miocene maritza east lignite bulgaria abstract numerous differences in the petrography and organic geochemistry of two tertiary low rank coal deposits of bulgaria formed within comparable depositional environments are outlined different floral assemblages are indicated as the main sources of organic matter for the eocene bourgas sub bituminous coals a warm climate plant community dominated by angiosperms is reflected in the biomarker composition whereas a coniferous flora was the main source of the resinous organic matter of the miocene maritza east lignite the results are in agreement with palaeobotanical data these differences in the peat forming vegetation of the paleogene compared to the neogene of bulgaria are attributed to decreasing temperature during the tertiary the abundance of resinous compounds relative to lipids from plant waxes long chain n alkanes as well as the preservation of plant tissue are mainly controlled by gymnosperm angiosperm ratios pristane phytane and diasterenes sterenes ratios reflect variations in redox conditions and the ph of the depositional environments caused by eustatic sea level changes freshwater inflow or varying ground water table changing eh and ph values are associated with differences in microbial activity controlling the extent of gelification of plant tissue bacteria most probably contributed to the aromatisation of triterpenoids in the mire enhanced thermal maturation of organic matter during diagenesis is reflected in higher contents of n alkanes and the presence of alkyl naphthalenes in the bourgas coals alkyl naphthalenes are thought to have been formed from pentacyclic triterpenoids rather than from resinous compounds

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

tracing martian surface interactions with the triple o isotope compositions of meteoritic phosphates abstract the triple oxygen isotope compositions of phosphate grains in six martian meteorites have been measured by secondary ion mass spectrometry sims and combined together with their chlorine isotope and halogen concentrations have been used to constrain hydrosphere lithosphere interactions on mars these samples include three enriched shergottites zagami roberts massif 04262 and larkman nunatak 12011 one depleted shergottite tissint an orthopyroxenite allan hills 84001 and a regolith breccia northwest africa 7533 the phosphates measured here have a range in 18 o 18o 16o sample 18o 16o standard 1 103 from 1 0 to 6 8 and could be a result of indigenous mantle values mixing with martian water or replacement reactions taking place on the surface of mars three samples have a 17 o 17 o 1000 1 18 o 1000 0 528 1 in equilibrium with the martian mantle alh 84001 tissint and zagami while three samples lar 12011 rbt 04262 and nwa 7533 have an elevated positive 17 o outside of analytical uncertainty of the martian fractionation line mfl the phosphates in the latter group also have positive and negative 37 cl 37cl 35cl sample 37cl 35cl standard 1 103 and enrichments in halogens not seen in the rest of the sample suite perchlorate formation on earth fractionates cl in both positive and negative directions and generates a correlated positive 17 o further perchlorate has been detected in wt amounts on the martian surface thus these results strongly suggest the presence of multiple cl isotope reservoirs on the martian surface that have interacted with the samples studied here over the last ca 2 ga of geologic time the weighted average of 17 o measurements from phosphate grains n 13 in nwa 7533 which are the explicit result of exchange reactions on the martian surface yields a statistically robust mean value of 1 39 0 19 2 mswd 1 5 p 0 13 this value likely represents an accurate estimate for an oxidized surface reservoir on mars

record of the ancient martian hydrosphere and atmosphere preserved in zircon from a martian meteorite how the atmosphere hydrosphere and surface materials interacted on early mars is poorly understood oxygen isotopic composition of zircon grains in a martian meteorite reveals a prolonged history of exchange between martian regolith and atmosphere

occurrence and palaeoenvironmental significance of aromatic hydrocarbon biomarkers in oligocene sediments from the mallik 5l 38 gas hydrate production research well canada abstract the aromatic hydrocarbon biomarker distributions of thirty oligocene sediment samples with different lithology lignite clay and sand from the japex jnoc gsc et al mallik 5l 38 gas hydrate production research well canada were analyzed using gas chromatography mass spectrometry gc ms the compositions vary with lithology indicating a change in palaeoenvironmental conditions at the time of deposition aromatic diterpenoids of the abietane type are more abundant in the lignite samples than in the clay samples and represent a gymnosperm e g conifer dominated palaeovegetation in contrast in the clay samples aromatic triterpenoids are generally preserved as major constituents indicating angiosperm dominated vegetation the sand samples contain only minor amounts of aromatic terpenoids but show a preference for diterpenoid gymnosperm markers to recognise gymnosperm versus angiosperm dominated palaeoenvironments a new ratio termed the angiosperm gymnosperm aromatic ratio agar has been developed thus the terpenoid distribution in the deltaic sediments provides information on the compositional changes in the plant community at the mallik site lignites and the hinterland clays over time concomitantly the changing dominance in the plant communities allows an insight into varying climatic conditions during the late oligocene in the area additionally the aromatic biomarker composition has been used to assess the level of thermal maturity of the organic matter in the mallik samples and indicates a prevailing immature character

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