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

carbon isotope systematics of a mantle hotspot a comparison of loihi seamount and morb glasses the carbon isotope geochemistry of glasses from loihi seamount has been compared with that of morb glasses stepped heating shows two carbon components in both sample suites 1 isotopically light carbon avg 13c 26 3 released 600 c regarded as indigenous the high temperature component in morb samples varied from 52 to 169 ppm c average 13c 6 6 consistent with previous studies overall mord average 13c 6 4 0 9 and new results for indian ocean glasses are similar to atlantic and pacific ocean samples carbon release profiles produced by stepped heating may be typical of locality but there are no significant differences in 13c values between morb samples from different areas lower yields 17 110 ppm c correlated with depth in the loihi samples suggest that they are partially degassed this degassing has not affected 13c values significantly avg 5 8 loihi tholeiites have higher 13c avg 5 6 than the alkali basalts avg 7 1 carbon abundances correlate well with he concentration data comparison of the 13c values with trace element and he sr nd and pb isotope data from the literature suggests that the loihi samples with highest 13c have high3he 4he and possibly the least depleted143nd 144nd and87sr 86sr the carbon isotope data are consistent with previous models for loihi involving several mantle sources lithospheric contamination and mixing the slightly higher 13c of loihi tholeiites suggests that the undegassed plume component manifested by high3he 4he values might have 13c about 1 higher than the morb average

marked decline in atmospheric carbon dioxide concentrations during the paleogene the relation between the partial pressure of atmospheric carbon dioxide pco2 and paleogene climate is poorly resolved we used stable carbon isotopic values of di unsaturated alkenones extracted from deep sea cores to reconstruct pco2 from the middle eocene to the late oligocene approximately 45 to 25 million years ago our results demonstrate that pco2 ranged between 1000 to 1500 parts per million by volume in the middle to late eocene then decreased in several steps during the oligocene and reached modern levels by the latest oligocene the fall in pco2 likely allowed for a critical expansion of ice sheets on antarctica and promoted conditions that forced the onset of terrestrial c4 photosynthesis

reevaluation of the oxygen isotopic composition of planktonic foraminifera experimental results and revised paleotemperature equations cultured planktonic foraminifera orbulina universa symbiotic and globigerina bulloides nonsymbiotic are used to reexamine temperature 18o relationships at 15 25 c relationships for both species can be described by linear equations equations for o universa grown under low light ll and high light hl share a slope of 4 80 0 21 c 1 with a hl ll offset of 0 33 due to symbiont photosynthetic activity the effect of co32 on o universa is 0 002 mol 1 kg 1 and is insensitive to temperature for g bulloides ontogenetic effects produce size related trends in temperature 18o whereby larger shells are enriched in 18o relative to smaller specimens the o universa temperature 18o relationships are more accurate than previously published equations for describing plankton tow data our equations do not explain planktonic core top data with the same precision but provide a good fit to benthic cibicidoides data below 10 c temperature 18o relationships for g bulloides provide good agreement with field data for this species from the northeast pacific

volcanism co2 and palaeoclimate a late jurassic early cretaceous carbon and oxygen isotope record a composite tethyan late jurassic early cretaceous carbon and oxygen isotope curve is presented c isotope data provide information on the evolution and perturbation of the global carbon cycle o isotope data are used as a palaeotemperature proxy in combination with palaeontological information the resulting trends in climate and in palaeoceanography are compared with biocalcification trends and oceanographic conditions favouring or inhibiting biocalcification positive c isotope anomalies in the valanginian and aptian correlate with episodes of increased volcanic activity regarded as a source of excess atmospheric carbon dioxide a major warming pulse accompanies the aptian but not the valanginian c isotope event the observed change in early aptian temperatures could have triggered the destabilization of sedimentary gas hydrates and the sudden release of methane to the biosphere as recorded as a distinct negative carbon isotope pulse preceding the positive excursion both c isotope anomalies are accompanied by biocalcification crises that may have been triggered by p co 2 induced changes in climate and in surface water chemistry elevated nutrient levels in river influenced coastal waters and in upwelling regions further weakened marine calcification these conditions contrast with normal trophic conditions prevailing in the latest jurassic and favouring biocalcification the c and o isotope curves record a stable mode of carbon cycling and stable temperatures we conclude that biocalcification is mostly triggered and inhibited by co 2 conditions in the atmosphere ocean system

carbon isotope evidence implying high o2 co2 ratios in the permo carboniferous atmosphere abstract theoretical models predict a marked increase in atmospheric o2 to 35 during the permo carboniferous 300 ma occurring against a low 0 03 co2 level an upper o2 value of 35 however remains disputed because ignition data indicate that excessive global forest fires would have ensued this uncertainty limits interpretation of the role played by atmospheric oxygen in late paleozoic biotic evolution here we describe new results from laboratory experiments with vascular land plants that establish that a rise in o2 to 35 increases isotopic fractionation 13c during growth relative to control plants grown at 21 o2 despite some effect of the background atmospheric co2 level on the magnitude of the increase we hypothesize that a substantial permo carboniferous rise in o2 could have imprinted a detectable geochemical signature in the plant fossil record over 50 carbon isotope measurements on intact carbon from four fossil plant clades with differing physiological ecologies and ranging in age from devonian to cretaceous reveal a substantial 13c anomaly 5 occurring between 300 and 250 ma the timing and direction of the 13c excursion is consistent with the effects of a high o2 atmosphere on plants as predicted from photosynthetic theory and observed in our experiments preliminary calibration of the fossil 13c record against experimental data yields a predicted o2 co2 mixing ratio of the ancient atmosphere consistent with that calculated from long term models of the global carbon and oxygen cycles we conclude that further work on the effects of o2 in the combustion of plant materials and the spread of wildfire is necessary before existing data can be used to reliably set the upper limit for paleo o2 levels

phanerozoic atmospheric co2 change evaluating geochemical and paleobiological approaches abstract the theory and use of geochemical modeling of the long term carbon cycle and four paleo pco 2 proxies are reviewed and discussed in order to discern the best applications for each method geochemical models provide pco 2 predictions for the entire phanerozoic but most existing models present 5 10 m y means and so often do not resolve short term excursions error estimates based on sensitivity analyses range from 75 200 ppmv for the tertiary to as much as 3000 ppmv during the early paleozoic the 13 c of pedogenic carbonates provide the best proxy based pco 2 estimates for the pre tertiary with error estimates ranging from 500 1000 ppmv pre devonian estimates should be treated cautiously error estimates for tertiary reconstructions via this proxy are higher than other proxies and models 400 500 ppmv and should not be solely relied upon we also show the importance of measuring the 13 c of coexisting organic matter instead of inferring its value from marine carbonates the 13 c of the organic remains of phytoplankton from sediment cores provide high temporal resolution up to 10 3 10 4 year high precision 25 100 ppmv for the tertiary to 150 200 ppmv for the cretaceous pco 2 estimates that can be near continuous for most of the tertiary its high temporal resolution and availability of continuous sequences is advantageous for studies aiming to discern short term excursions this method however must correct for changes in growth rate and oxygen level at elevated pco 2 750 1250 ppmv this proxy loses its sensitivity and is not useful the stomatal density and stomatal index of land plants also provide high temporal resolution 2 year high precision 10 40 ppmv for the tertiary and possibly cretaceous pco 2 estimates and so also is ideal for discerning short term excursions unfortunately this proxy also loses sensitivity at some level of pco 2 above 350 ppmv which currently is largely undetermined our analysis of the recently developed 11 b technique shows that it currently is not yet well constrained most importantly it requires the assumption that the boron isotopic composition of the ocean remains nearly constant through time in addition it assumes that there are no biological or temperature effects and that diagenetic alteration of the boron isotopic composition does not occur a fifth co 2 proxy based on the redox chemistry of marine cerium has several fundamental flaws and is not discussed in detail here

stable carbon isotopes of c3 plant resins and ambers record changes in atmospheric oxygen since the triassic estimating the partial pressure of atmospheric oxygen po2 in the geological past has been challenging because of the lack of reliable proxies here we develop a technique to estimate paleo po2 using the stable carbon isotope composition d 13 c of plant resins including amber copal and resinite from a wide range of localities and ages triassic to modern plant resins are particularly suitable as proxies because their highly cross linked terpenoid structures allow the preservation of pristine d 13 cs ignatures over geological timescales the distribution of d 13 c values of modern resins n 126 indicates that a resin producing plant families generally have a similar fractionation behavior during resin biosynthesis and b the fractionation observed in resins is similar to that of bulk plant matter resins exhibit a natural variability in d 13 c of around 8 d 13 cr ange 31 to 23 m ean 27 which is caused by local environmental and ecological factors e g water availability water composition light exposure temperature nutrient availability to minimize the effects of local conditions and to determine long term changes in the d 13 co f resins we used mean d 13 c values d 13 c resin for each geological resin deposit fossil resins n 412 are generally enriched in 13 c compared to their modern counterparts with shifts in d 13 c resin of up to 6 these isotopic shifts follow distinctive trends through time which are unrelated to post depositional processes including polymerization and diagenesis the most enriched fossil resin samples with a d 13 c resin between 22 and 21 formed during the triassic the mid cretaceous and the early eocene experimental evidence and theoretical considerations suggest that neither change in pco2 nor in the d 13 c of atmospheric co2 can account for the observed shifts in d 13 c resin the fractionation of 13 c in resin producing plants d 13 c instead is primarily influenced by atmospheric po2 with more fractionation occurring at higher po2 the enriched d 13 c resin values suggest that atmospheric po2 during most of the mesozoic and cenozoic was considerably lower po2 10 20 than today po2 21 in addition a correlation between the d 13 c resin and the marine d 18 o record implies that po2 pco2 and global temperatures were inversely linked which suggests that intervals of low po2 were generally accompanied by high pco2 and elevated global temperatures intervals with the lowest inferred po2 including the mid cretaceous and the early eocene were preceded by large scale volcanism during the emplacement of large igneous provinces lips this suggests that the influx of mantle derived volcanic co2 triggered an initial phase of warming which led to an increase in oxidative weathering thereby further increasing greenhouse forcing this process resulted in the rapid decline of atmospheric po2 during the mid cretaceous and the early eocene greenhouse periods after the cessation in lip volcanism and the decrease in oxidative weathering rates atmospheric po2 levels continuously increased over tens of millions of years whereas co2 levels and temperatures continuously declined these findings suggest that atmospheric po2 had a considerable impact on the evolution of the climate on earth and that the d 13 c of fossil resins can be used as a novel tool to assess the changes of atmospheric compositions since the emergence of resin producing plants in the paleozoic

carbon isotope behaviour in wood and cellulose during artificial aging abstract modern wood was subjected to an artificial decay process to investigate its behaviour with respect to the stable carbon isotope composition of wood and the corresponding cellulose four different woods were used namely oak quercus robur beech fagus sylvatica pine pinus sylvestris sequoia sequoiadendron giganteum and pure spruce cellulose the process of decay was simulated by heating samples in water at 180 c from minutes to months during the decay period the carbon content of wood increased to almost 70 while the cellulose content decreased gradually to zero the degradation proceeds according to a two stage process an initial very fast break down is followed by a rather slow degradation after a strong discrimination against 13 c during the initial phase the 13c 12c ratio increases again mostly up to its initial value the carbon isotope trend for cellulose shows a similar pattern though it is less pronounced maximum discrimination was 1 relative to the untreated wood 13c values of cellulose decreased by up to 0 3 the 13 c depletion is presumably a consequence of the preferential decomposition of cellulose as compared to lignin data on fossil trees are compared with the results obtained from this treatment of aging the 13 c decrease is in line with observations from these fossil woods but the ensuing 13 c enrichment is at most weakly to be seen

phanerozoic concentrations of atmospheric oxygen reconstructed from sedimentary charcoal varying concentrations of atmospheric oxygen have affected the development of animals and the role of wildfire in ecosystems reconstructions of past oxygen concentrations from fossil charcoal constrain atmospheric oxygenation over the past 400 million years variations of the earth s atmospheric oxygen concentration po2 are thought to be closely tied to the evolution of life with strong feedbacks between uni and multicellular life and oxygen1 2 on the geologic timescale po2 is regulated by the burial of organic carbon and sulphur as well as by weathering3 reconstructions of atmospheric o2 for the past 400 million years have therefore been based on geochemical models of carbon and sulphur cycling4 5 6 however these reconstructions vary widely4 5 6 7 8 9 10 particularly for the mesozoic and early cenozoic eras here we show that the abundance of charcoal in mire settings is controlled by po2 and use this proxy to reconstruct the concentration of atmospheric oxygen for the past 400 million years we estimate that po2 was continuously above 26 during the carboniferous and permian periods and that it declined abruptly around the time of the permian triassic mass extinction during the triassic and jurassic periods po2 fluctuated cyclically with amplitudes up to 10 and a frequency of 20 30 million years atmospheric oxygen concentrations have declined steadily from the middle of the cretaceous period to present day values of about 21 we conclude however that variation in po2 was not the main driver of the loss of faunal diversity during the permo triassic and triassic jurassic mass extinction events

middle late cretaceous climate of the southern high latitudes stable isotopic evidence for minimal equator to pole thermal gradients a detailed 18 o and 13 c stratigraphy has been generated from analysis of well preserved albian early maastrichtian foraminifera from deep sea drilling project dsdp sites 511 and 327 falkland plateau 58 s 62 s paleolatitude in the southern south atlantic and cenomanian and coniacian santonian foraminifera from dsdp site 258 naturaliste plateau 58 s paleolatitude in the southern indian ocean these results when combined with previously published maastrichtian stable isotope data from ocean drilling program odp site 690 weddell sea 65 s paleolatitude provide new insight into the climatic and oceanographic history of the southern high latitudes during middle late cretaceous time the planktonic foraminifer 18 o curves reveal a gradual warming of surface waters from the albian through the cenomanian followed by extremely warm surface waters from the turonian through the early campanian long term cooling of surface waters began in the late early campanian and continued through the end of the maastrichtian the benthic foraminifer 18 o record generally parallels changes in the oxygen isotopic curves defined by shallow dwelling planktonic foraminifera the vertical oxygen and carbon isotopic gradients were relatively low during the albian cenomanian high from the turonian early campanian and then low during the late campanian and maastrichtian foraminiferal oxygen isotopic data from published sources and this study are averaged for each site corrected for latitudinal changes in salinity based on modern day surface water values and plotted versus paleolatitude for the late albian coniacian santonian and late maastrichtian differences between lowand high latitude surface water paleotemperatures are estimated at 14 c during the late albian and late maastrichtian but the coniacian santonian reconstruction reveals only a 0 4 c latitudinal temperature gradient uncertainty regarding cretaceous salinity gradients and possible diagenetic alteration of 18 o values introduce error into our estimates of paleolatitudinal thermal gradients however apparent low equator to pole temperature differences could indicate much higher poleward heat transport than at present

environmental changes since 13 000 cal bp reflected in magnetic and sedimentological properties of sediments from lake holzmaar germany abstract late and postglacial sediments from a german maar lake holzmaar in the west eifel volcanic field were investigated with rockmagnetic and sedimentological methods the concentration of magnetic minerals is very variable and zones exist where magnetic properties are dominated by paramagnetic minerals remanence carrying ferromagnetic minerals are dominated by a low coercivity fraction identified by its curie temperature and by scanning electron microscopy as titanomagnetite with a grain size range between a few microns and 25 m an additional high coercivity phase probably hematite is present throughout the entire record in low concentrations rockmagnetic results indicate the possible postdepositional dissolution of titano magnetite and the authigenic growth of greigite in one confined section a positive correlation between initial magnetic susceptibility and sediment accumulation rate and between and the non arboreal pollen percentage is observed while and organic carbon content show a negative correlation these coeval variations are due to a nearly exclusively detrital sedimentary input the variations show a broad dependence on climatic conditions for times prior to significant human activities in the region and the impact of the human settlement history afterwards early holocene climatic variations indicating two cooling events agree with ice rafted debris events of the north atlantic

δ13c and δ18o values of triassic brachiopods and carbonate rocks as proxies for coeval seawater and palaeotemperature abstract a dataset of 160 isotope 13c and 18o values from anisian ladinian carnian and rhaetian articulate brachiopod shells complemented by 158 carbon and oxygen isotope values from whole rock carbonates define the first continuous stable isotope baseline trends for the triassic seawater the carbon isotope data suggest the existence of several short term high amplitude excursions in the early triassic followed by a predominance of values around 0 5 1 during the middle triassic a rise to 3 5 during the carnian plateau at this level during the late carnian to early norian and a 1 5 decline in the middle norian to values around 2 during the late norian rhaetian interval the causation scenarios for these rapid oscillations are at present equivocal but may in part reflect a biological instability of the carbon cycle following the recovery from the end permian extinction event and or an input of mantle derived co2 from enhanced volcanic activity the 18o values from well preserved brachiopods from the tethyan realm range from 3 9 to 0 6 v pdb these values require open marine triassic seawater 18o values close to 0 v smow for the calculated temperatures to be within the range of tolerance of the coexisting reef building corals a 2 18o increase within the uppermost cordevolian and early julian suggests either a distinct temperature decline in the southern alps during that time interval an increase in seawater salinity or their combination oxygen isotope values for the muschelkalk brachiopods range between 6 2 and 2 0 and likely reflect a strong influx of meteoric waters into the germanic basin that shifted the oxygen isotopes to more negative values

eocene amber from the pacific coast of north america fossil plant resins are common in late cretaceous rocks of north america and in oligocene and younger sediments of equatorial and southern hemisphere locations the scarcity of amber in early tertiary rocks however poses puzzling geological questions detailed examination of mid eocene amber bearing sediments from coalmont british columbia and seattle washington indicates that resins were produced by taxodiaceous conifers with metasequoia occidentalis being the most likely source laboratory heating experiments and paleotemperature analysis of these sediments based on coal rank and vitrinite reflectance suggest that burial temperatures may significantly affect infrared spectra of amber a phenomenon not previously recognized by researchers who have long used spectral characteristics to speculate on the botanical origin of fossil resins the occurrence of amber in mid eocene rocks of the pacific northwest arkansas and southern california suggests that resin production ended as the climate of north america cooled during the mid tertiary and that late tertiary amber was produced by flowering tropical plants not present in the eocene forests this evolutionary record appears somewhat different from that of western europe where progressive southward migration of coniferous amber forests occurred during mid tertiary time

carbon isotope ratio of cenozoic co2 a comparative evaluation of available geochemical proxies 1 the carbon isotope ratio 13c of plant material is commonly used to reconstruct the relative distribution of c3 and c4 plants in ancient ecosystems however such estimates depend on the 13c of atmospheric co2 13cco2 at the time which likely varied throughout earth history for this study we use benthic and planktonic 13c and 18o records to reconstruct a long term record of cenozoic 13cco2 confidence intervals for 13cco2 values are assigned after careful consideration of equilibrium and non equilibrium isotope effects and processes as well as resolution of the data we find that benthic foraminifera better constrain 13cco2 compared to planktonic foraminiferal records which are influenced by photosymbiotes depth of production seasonal variability and preservation furthermore sensitivity analyses designed to quantify the effects of temperature uncertainty and diagenesis on benthic foraminifera 13c and 18o values indicate that these factors act to offset one another our reconstruction suggests that cenozoic 13cco2 averaged 6 1 0 6 1 while only 11 2 million of the last 65 5 million years correspond to the pre industrial value of 6 5 with 90 confidence here 13cco2 also displays significant variations throughout the record at times departing from the pre industrial value by more than 2 thus the observed variability in 13cco2 should be considered in isotopic reconstructions of ancient terrestrial plant ecosystems especially during the late and middle miocene times of presumed c4 grassland expansion

age and paleogeographical origin of dominican amber the age and depositional history of dominican amber bearing deposits have not been well constrained resinites of different ages exist in hispaniola but all of the main amberiferous deposits in the dominican republic including those famous for yielding biological inclusions were formed in a single sedimentary basin during the late early miocene through early middle miocene 15 to 20 million years ago according to available biostratigraphic and paleogeographic data there is little evidence for extensive reworking or redeposition in either time or space the brevity of the depositional interval less than 5 million years provides a temporal benchmark that can be used to calibrate rates of molecular evolution in amber taxa

variability in late cretaceous climate and deep waters evidence from stable isotopes abstract strong climatic and temperature fluctuations mark the late campanian and maastrichtian as indicated by stable isotope records from the equatorial pacific site 463 and middle and high latitude south atlantic sites 525 689 and 690 the first major global cooling decreased intermediate water temperatures iwt by 5 6 c between 73 70 ma at the same time sea surface temperature sst decreased by 4 5 c in middle and high latitudes intermediate waters iw temporarily warmed by 2 c in low and middle latitudes between 70 68 5 ma global cooling resumed between 68 5 65 5 ma when iwt decreased by 3 4 c and sst by 5 c in middle latitudes about 450 ka before the cretaceous tertiary boundary rapid global warming increased iwt and sst by 3 4 c though sst in the tropics changed little during the last 200 ka of the maastrichtian climate cooled rapidly with iwt and sst decreasing by 2 3 c during the global cooling at 71 70 ma and possibly at 67 65 5 ma the sources of cold intermediate waters in the equatorial pacific indo pacific and south atlantic were derived from the high latitude north pacific in contrast during the global climate warming between 65 2 65 4 ma the middle latitude south atlantic was closest to the source of iw production and implies that the low latitude tethys played a major role in global climate change climate changes sea level fluctuations and associated restricted seaways appear to be the most likely mechanisms for the alternating sources of iw production

an isotopic study of paleosol carbonates from olduvai gorge the isotopic composition of paleosol carbonates from olduvai gorge can be used to give estimates of the paleoclimatic history of east africa during the plio pleistocene oxygen isotopes are indicative of major changes in the isotopic composition of meteoric water while carbon isotopes are indicative of major changes in the fraction of biomass using the hatch slack c4 photosynthetic pathway three major periods of climatic change in this terrestrial setting occurred at about 1 67 1 3 and 0 6 myr these involved major changes in flora as well as major changes in the isotopic composition of meteoric water overall the climate has become warmer and more arid over the past 2 2 myr

latest on the absolute age of the paleocene eocene thermal maximum petm new insights from exact stratigraphic position of key ash layers 19 and 17 abstract we constructed a precise early eocene orbital cyclostratigraphy for dsdp site 550 leg 80 goban spur north atlantic utilizing precession related cycles as represented in a high resolution x ray fluorescence based barium core log based on counting of those cycles we constrain the exact timing of two volcanic ash layers in site 550 which correlate to ashes 19 and 17 of the fur formation in denmark the ashes relative to the onset of the paleocene eocene thermal maximum petm are offset by 862 kyr and 672 kyr respectively when combined with published absolute ages for ash 17 the absolute age for the onset of the petm is consistent with astronomically calibrated ages using the current absolute age of 28 02 ma for the fish canyon tuff fct standard for calibrating the absolute age of ash 17 is consistent with tuning option 2 in the astronomically calibrated paleocene time scale of westerhold et al 2008 westerhold t rohl u raffi i fornaciari e monechi s reale v bowles j and evans h f 2008 astronomical calibration of the paleocene time palaeogeography palaeoclimatology palaeoecology v 257 p 377 403 using the recently recalibrated absolute age of 28 201 ma for the fct standard is consistent with tuning option 3 in the astronomically calibrated paleocene time scale the new results do not support the existence of any additional 405 kyr cycle in the early paleocene astronomically tuned time scale

a new model for atmospheric oxygen over phanerozoic time a mathematical model has been constructed that enables calculation of the level of atmospheric o2 over the past 570 my from rates of burial and weathering of organic carbon c and pyrite sulfur s burial rates as a function of time are calculated from an assumed constant worldwide clastic sedimentation rate and the relative abundance and c and s contents of the three rock types marine sandstones and shales coal basin sediments and other non marine clastics red beds arkoses by our model values of o2 versus time using a constant total sedimentation rate agree with those for variable sedimentation derived from present day rock abundances and estimates of erosional losses since deposition this agreement is the result of our reliance on the idea that any increase in total worldwide sediment burial with consequently faster burial of c and s and greater o2 production must be accompanied by a corresponding increase in erosion and increased exposure of c and s on the continents to o2 consumption via weathering it is the redistribution of sediment between the three different rock types and not total sedimentation rate that is important in o2 control to add stability to the system negative feedback against excessive o2 fluctuation was provided in the modeling by the geologically reasonable assignment of higher weathering rates to younger rocks resulting in rapid recycling of c and s we did not use direct o2 negative feedback on either weathering of c and s or burial of c because weathering rates are assumed to be limited by uplift and erosion and the burial rate of c limited by the rate of sediment deposition the latter assumption is the result of modern sediment studies which show that marine organic matter burial occurs mainly in oxygenated shallow water and is limited by the rate of supply of nutrients to the oceans by rivers results of the modeling indicate that atmospheric o2 probably has varied appreciably over phanerozoic time during the late carboniferous and permian periods o2 was higher than previously because of the rise of vascular land plants and the widespread burial of organic matter in vast coal swamps a large decrease in o2 during the late permian was due probably to the drying up of the coal swamps and deposition of a large proportion of total sediment in c and s free continental red beds sensitivity study shows that major parameters affecting results are the mean c concentration in coal basins and the relative sizes of the reservoirs of young rapidly recycled versus old rocks less sensitivity was found for changes over time in total land area undergoing weathering and the use of direct o2 negative feedback on marine carbon burial good agreement for rates of c burial calculated via our model and via independent models which are based on the use of stable carbon isotopes indicates that the dominant factor that has brought about changes in atmospheric o2 level and the isotopic composition of dissolved inorganic carbon in seawater over phanerozoic time is sedimentation and not weathering or higher temperature phenomena such as basalt seawater reaction

upper cretaceous stable carbon isotope stratigraphy of terrestrial organic matter from sakhalin russian far east a proxy for the isotopic composition of paleoatmospheric co2 abstract time stratigraphic patterns of stable carbon isotopic ratios recorded in terrestrial organic matter from cenomanian maastrichtian successions for the russian far east can be correlated to those of carbonate carbon from well studied successions for other parts of the world age indicative biostratigraphy based on regional ammonoids and inoceramid bivalves are well established in japan and can be applied to the whole cretaceous succession except for the upper cenomanian lower turonian and the upper part of the maastrichtian zones lacking macrofossils globally correlative carbon isotopic events previously documented with carbonate carbon from europe and with carbonate carbon and marine organic matter from the u s western interior are recognized with similar magnitude through uppermost cenomanian lower campanian in ascending order these events are positive spike across the cenomanian turonian boundary step like leveled segment followed by negative shift lower middle turonian trough like negative excursion middle upper turonian positive rebound coupled with following broad peak coniacian and positive peak basal campanian followed by modest negative excursion the parallel fluctuation of the 13 c value between the terrestrial organic matter and carbonate suggests carbon isotopic equilibrium between surface seawater and atmospheric co 2 and demonstrates that the isotopic curve of terrestrial organic carbon can be used to monitor carbon isotopic fluctuations of co 2 in the ocean atmosphere system in the upper campanian and maastrichtian a negative 13 c excursion within chron 33r and a following rapid rebound can be correlated with the same distinctive carbon isotopic feature of carbonate observed in the deep sea cores from south and north atlantic the indian and the pacific oceans within this interval the 13 c value of terrestrial organic matter also reflects carbon isotopic fluctuation of the global co 2 reservoir with relatively minor regional local noise

carbon isotope composition of lower cretaceous fossil wood ocean atmosphere chemistry and relation to sea level change the carbon isotope composition of fossil wood fragments collected through a biostratigraphically well constructed aptian lower cretaceous shallow marine siliciclastic succession on the isle of wight southern britain shows distinct variations with time the results indicate that the stratigraphic signature of delta sup 13 c sub wood through the aptian was influenced primarily by fluctuations in the isotopic composition of co sub 2 in the global ocean atmosphere system as registered in marine carbonates elsewhere and was not governed by local paleoenvironmental and or paleoecological factors negative and positive excursions in delta sup 13 c sub wood through the lower aptian occur in phase with inferred transgressions and regressions respectively a pattern that contrasts with that observed in many previous studies for different time intervals the relationship between delta sup 13 c variations and relative sea level change is tentatively interpreted as a response to various climatic and eustatic factors relating to rapid sea floor spreading thermal uplift of ocean floor emplacement of plateaus volcanic co sub 2 emissions weathering and sedimentary rate

secular change of the seasonal variation in sea level and of the pole tide in the baltic sea regular sea level observations have been performed in stockholm since 1825 yielding the longest unbroken series of monthly mean sea levels in the world applying fourier analysis to these data we have investigated the annual and semiannual sea level variations as well as the pole tide whereas the semiannual variation has a fairly constant amplitude of about 4 cm the annual variation shows a secular increase in amplitude from 8 to 10 cm this increase is statistically significant at the 99 level it is suggested that this change might be connected to secular changes of the oceanographic conditions that have been observed to occur in the northeastern north atlantic especially a movement of the oceanic polar front the pole tide also shows a secular change the amplitude for the 14 3 month chandler period was less than 2 cm below the noise level during the previous century during our own century the amplitude is 3 cm 6 times the equilibrium tide this might indicate that a meteorological forcing component close to the chandler period has changed and added variability to the sea level at this period

environmental history of the german lower rhine embayment during the middle miocene as reflected by carbon isotopes in brown coal stable carbon isotope investigations have been carried out on miocene brown coal from the garzweiler seam of the german lower rhine embayment material studied included fossil wood from seven different taxa and brown coal matrix isotope results from macrofossil analysis show variations of more than 6 within individual samples and reveal a general isotopic difference between angiosperm and gymnosperm wood specimens according to mean carbon isotope values found for gymnosperms angiosperms and brown coal matrix 23 3 26 0 and 25 8 the peat forming vegetation of the garzweiler seam was dominated by angiosperm taxa results from brown coal matrix establish a continuous high resolution depth profile of carbon isotope variations during the late middle miocene they show a significant and characteristic isotope pattern with distinct medium and short term cycles high frequency variations in the two main units of garzweiler seam locally split into three units the medium term 13c variations are most likely caused by varying proportions of gymnosperms within the peat forming vegetation while high frequency oscillations seem to be a direct signal of environmental changes a long term decline of carbon isotope values observed within the complete garzweiler seam from base to top is presumably due to a cooling trend in the miocene

the paleozoic to mesozoic carbon cycle revisited the carbon isotopic composition of terrestrial organic matter 1 two thousand one hundred forty eight carbon isotope values for terrestrial organic matter plant fossils coal bulk terrestrial organic matter provide a proxy record for temporal changes in the global carbon cycle 13ctom 13ccarb and 13cco2 allow a full evaluation of carbon transfer in the atmosphere ocean system as well as between the marine and the terrestrial realm the temporal evolution of 13ctom parallels respective data sets from marine carbonate carbon thus reflecting the linkage between both reservoirs via atmospheric carbon dioxide on the basis of a comparison between measured and predicted isotope records for 13ctom changes in the carbon isotopic fractionation associated with plant metabolism are discernible this contradicts the notion of an invariable carbon isotopic fractionation associated with c3 plant metabolism in light of results from current plant growth experiments these changes are viewed as dependent on the atmospheric o2 co2 hence 13ctom might serve as a proxy signal for atmospheric composition

geology of an amber locality in the hukawng valley northern myanmar abstract amber burmite from the hukawng valley of myanmar has been known since at least the 1st century ad it is currently being produced from a hill known as noije bum which was first documented as a source of amber in 1836 several geologists visited the locality between 1892 and 1930 all of them believed that the host rocks to the amber are tertiary most said eocene in age and this conclusion has been widely quoted in the literature however recent work indicates a cretaceous age insect inclusions in amber are considered to be turonian cenomanian and a specimen of the ammonite mortoniceras of middle upper albian age was discovered during the authors visit palynomorphs in samples collected by the authors suggest that the amber bearing horizon is upper albian to lower cenomanian the preponderance of the evidence suggests that both rocks and amber are most probably upper albian this determination is significant for the study of insect evolution indicating that the oldest known definitive ants have been identified in this amber american museum novitates 3361 2002 72 this site occurs within the hukawng basin which is comprised of folded sedimentary volcanic rocks of cretaceous and cenozoic age the mine exposes a variety of clastic sedimentary rocks with thin limestone beds and abundant carbonaceous material the sediments were deposited in a nearshore marine environment such as a bay or estuary amber is found in a fine clastic facies principally as disk shaped clasts oriented parallel to bedding a minority occurs as runnels stalactite shaped with concentric layering caused by recurring flows of resin an upper albian age is similar to that of orbitolina limestones known from a number of locations in northern myanmar one of these at nam sakhaw 90 km sw of noije bum has also been a source of amber

release of methane from a volcanic basin as a mechanism for initial eocene global warming a 200 000 yr interval of extreme global warming marked the start of the eocene epoch about 55 million years ago negative carbon and oxygen isotope excursions in marine and terrestrial sediments show that this event was linked to a massive and rapid approximately 10 000 yr input of isotopically depleted carbon it has been suggested previously that extensive melting of gas hydrates buried in marine sediments may represent the carbon source and has caused the global climate change large scale hydrate melting however requires a hitherto unknown triggering mechanism here we present evidence for the presence of thousands of hydrothermal vent complexes identified on seismic reflection profiles from the voring and more basins in the norwegian sea we propose that intrusion of voluminous mantle derived melts in carbon rich sedimentary strata in the northeast atlantic may have caused an explosive release of methane transported to the ocean or atmosphere through the vent complexes close to the palaeocene eocene boundary similar volcanic and metamorphic processes may explain climate events associated with other large igneous provinces such as the siberian traps approximately 250 million years ago and the karoo igneous province approximately 183 million years ago