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

on the mobility of pyroclastic currents in light of deposit thickness and clast size trends abstract pyroclastic currents pcs represent the most hazardous manifestations of explosive volcanic activity the evaluation of their mobility as related to the eruptive source parameters and the interactions with the surroundings along their path is crucial for hazard assessment at active volcanoes in order to define the areas exposed to their impacts here we report on two case studies from the latera volcanic complex vulsini volcanic district central italy that may approach the two end members of the classical spectrum of pc dynamics in terms of particle concentration and dominant flow regime i e dilute turbulent vs concentrated laminar pcs for the two examples we document specific and contrasting variation trends of deposit thickness and maximum lithic and pumice clast sizes with distance from vent which provide a further characterization in terms of forced vs inertial flow behavior in the first case thickness and maximum lithic and pumice sizes show a mild linear decrease with distance implying a sort of balance between forced and inertial regimes flow pressure and mass progressively drop via deposition along with flow competence for given source conditions i e mass eruption rate fountaining height erupting mixture etc and slope angle of topography the pc runout depends primarily on the waning density contrast between the flow and the surrounding atmosphere density current ending with the loft of the current the second case representative of moderate to large volume dense pcs derived by continuous feeding with high mass discharge rate i e from collapsing plinian columns or caldera forming events shows an increase of deposit thickness with distance which is accompanied by opposite lithic and pumice clast size distance trends i e decreasing lithic sizes and increasing pumice sizes downcurrent compatible with high particle concentration and forced non turbulent granular flow regime by analogy with the mobility of dry debris flows we suggest that the sliding component of transport which prevails in proximal to intermediate settings may account for the prevailing tendency of the pc to transport than to deposit which leaves behind relatively thin sheets with coarse lithics while the dominant spreading component downcurrent would result in increasing accumulation and the stacking of coarse pumice rich flow lobes in more distal settings the spreading component of transport would become more and more important with increasing material supply at pc source resulting in additional runout these findings cast new light on the first order controlling factors of flow mobility for the two pc end members laying the groundwork for determining the most relevant pc hazard parameters i e the maximum runout and the flow properties upon impact dynamic pressure burial potential temperature

biomarkers as proxies for plant inputs to peats an example from a sub boreal ombrotrophic bog lipid distributions in modern peat forming plants were determined and compared to biomarkers recovered from a ca 2800 year old peat deposited in a dutch ombrotrophic bog the peat section spans a well constrained shift in local hydrology and vegetation and potential molecular proxies for plant inputs were directly tested against the macrofossil record based on the analyses of modern plants low molecular weight lmw n alkanes c23 c25 and high molecular weight n alkanes c33 are proposed as potential biomarkers for sphagnum and non sphagnum inputs respectively consistent with this in the bargerveen peat core lmw n alkane abundances increase and hmw n alkane abundances decrease coincident with the shift to sphagnum dominated peat additional potential proxies include the abundances of c22 alkanedioic acid and phytenyl phytenoate as sphagnum indicators and the abundances of the triterpenoids taraxer 14 ene and taraxast 20 ene as biomarkers for ericaceae rootlets

neogene vegetation of the meyer desert formation sirius group transantarctic mountains antarctica a tundra vegetation consisting of at least 18 plant species is described from the meyer desert formation which outcrops along the beardmore glacier in the transantarctic mountains about 500 km from the south pole the fossils include pollen seeds fruits flowers leaves wood and in situ plants of which wood and leaves of nothofagus and a pollen assemblage had been previously reported the plants include a cryptogamic flora of mosses and liverworts conifers and angiosperms in the families gramineae cyperaceae nothofagaceae ranunculaceae hippuridaceae caryophyllaceae and chenopodiaceae or myrtaceae the plants grew in a weakly developed soil formed within a complex periglacial environment that included moraines glacial outwash streams well drained gravel ridges and poorly drained depressions in which peat and marl were being deposited d 2004 elsevier b v all rights reserved

glacial interglacial variations in carbon cycling revealed by molecular and isotope stratigraphy of lake nkunga mt kenya east africa abstract the lipid content n alkanes n alkanols n alkanoic acids and the 13c values of these lipids were measured in nineteen sediment samples taken from a 21 18 m long core from lake nkunga a high altitude 1820 m a s l freshwater lake situated in the montane rain forest on mt kenya the record spans the early last glacial marine isotope stages 5a to 4 and the late holocene 1030 45 14c yr bp to the present day the intervening hiatus spans the last glacial maximum and the early to mid holocene the molecular biogeochemical results are interpreted in terms of past changes in climate vegetation and atmospheric co2 concentration three different sources of organic matter input were identified from the n alkyl lipids namely terrestrial plants aquatic plants and algae unusual distribution patterns of dominant mid chain length n alkanes c23 25 n alkanols c22 24 and n alkanoic acids c22 24 are attributed to aquatic macrophytes an 11 decrease in bulk carbon isotope values between the sediments of early glacial 17 and late holocene age 28 is also apparent in the individual homologues of the n alkyl lipids the observed isotopic shift in terrestrial higher plant biomarkers is similar to that observed in nearby sacred lake and is consistent with an expansion of c4 grasses or sedges during the early glacial the corresponding vegetation was a dry montane juniper olive forest with a grassy understorey representing cold dry conditions with lower co2

latest cretaceous earliest paleogene vegetation and climate change at the high southern latitudes palynological evidence from seymour island antarctic peninsula abstract fluctuations in late cretaceous climate were already influencing biotic change prior to the environmental upheaval at the cretaceous paleogene k pg boundary but their general nature magnitude and timing remain controversial a high resolution dataset on terrestrially derived palynomorphs is presented from the high southern palaeolatitudes that unlocks details of small scale climate variability throughout this period of significant global change specifically this is a quantitative spore and pollen analysis of an expanded uppermost cretaceous to lowermost paleogene maastrichtian earliest danian shallow marine sedimentary succession from seymour island off the northeastern tip of the antarctic peninsula then as now located at 65 s using nearest living relatives the first detailed vegetation habitat and climate reconstruction is presented for the emergent volcanic arc at this time on the coastal lowlands a cool to warm temperate rainforest is envisaged growing in a riverine landscape with both wet river margin pond and relatively dry interfluve canopy gap habitats diverse podocarps and southern beech trees grew alongside angiosperm herbs and shrubs in mean annual temperatures of 10 15 c higher altitude araucarian forests gave way to open ericaceous heathland beyond the tree line in subalpine to alpine conditions with mean annual temperatures of a cold 5 8 c there is no exact modern botanical equivalent but the closest modern flora is that of the andes of southern chile and argentina maastrichtian climate is shown to have fluctuated from cool humid conditions through a rapid warming 2 million years prior to the k pg transition followed by cooling during the earliest danian a trend supported by previous work on this interval

on marine microfossil transport and pathways in antarctica during the late neogene evidence from the sirius group at mount fleming there are two extreme views of the evolution of the pliocene antarctic ice sheet dynamicists argue for ice sheet reduction and reexpansion on the basis of pliocene marine diatoms in a glacial deposit the sirius group that is widespread in the transantarctic mountains stabilists argue from other evidence that the antarctic cryosphere remained essentially constant in area and volume they propose marine diatom transport by eolian processes and emplacement into terrestrial glacial strata hence the inferred source area and transport mechanism of marine diatoms are of critical importance we tested the reduction hypothesis on an important outcrop of the sirius group at mount fleming south victoria land we observed very few unidentifiable marine diatom fragments in sirius group strata in contrast marine diatoms enclosed in a surface diamicton covering the sirius group were more abundant and identifiable our study further indicates that the sirius group at mount fleming was not deposited by the east antarctic ice sheet but rather by alpine ice originating on the transantarctic mountains on the basis of both data sets we infer that marine diatoms postdate sirius group deposition at mount fleming and that transport was by wind and we advance alternative scenarios for their source and transport pathways

the petrology of greek brown coals abstract results are given in the petrography of greek coals collected from most of the major coal bearing basins in greece rank was determined by measuring reflectances on the maceral varieties eu ulminite a and eu ulminite b and on the maceral textinite reflectances obtained from these components indicate a coalification stage of brown coal for all samples within this group of samples there is however a fairly wide scatter of reflectance values indicating for some of them the transition zone from peat to brown coal and for others a coalification stage close to the transition into bituminous coals reflectances obtained from eu ulminite a and eu ulminite b were found to correlate well with chemical rank parameters such as volatile matter and calorific value composition was determined by maceral analysis the coals are in general characterized by low amounts of macerals of the inertinite group low to intermediate amounts of macerals of the liptinite group and high amounts of macerals of the huminite group within the latter group densinite attrinite eu ulminite and textinite make up the bulk of the samples typical macerals observed in the coals are illustrated by two black and white and three colour plates cluster analysis based on maceral distribution mineral matter and reflectance indicates that the samples studied can be divided into three major groups the first one is dominated by eu ulminite and densinite with relatively high reflectances the second is dominated by attrinite textinite and texto ulminite with somewhat lower reflectances the third is represented by a single sample in which textinite and resinite are the most abundant macerals this sample also has the lowest reflectance

a comparison of pyroclastic flow and debris avalanche mobility many pyroclastic flows have runout distances longer than expected from basic frictional arguments in these cases the ratio of the height descended h and the runout l are as small as 0 2 a feature which has been attributed to fluidization however significant fluidization by gases is now considered unlikely during emplacement of debris avalanches where h l and volume are inversely related we determine whether pyroclastic flows are more mobile than debris avalanches of the same volume and if different emplacement mechanisms are needed to describe their runout h l and volume data were compiled for 34 nonvolcanic and 40 volcanic debris avalanche deposits as well as 15 pyroclastic flow deposits systematic differences in the volume versus h l plots were explored by statistical analysis results show an inverse relationship between h l and volume for both nonvolcanic and volcanic debris avalanche deposits as expected and also for pyroclastic flow deposits regression lines for plots of pyroclastic flow and volcanic debris avalanche data are statistically indistinguishable and the non volcanic debris avalanche line is parallel to the other two we argue that the nonvolcanic and volcanic debris avalanche differences are due to material properties rather than emplacement mechanisms therefore since pyroclastic flows and volcanic debris avalanches have indistinguishable h l versus volume it is unlikely that pyroclastic flows have a significantly different primary emplacement mechanism based on the data in hand we conclude that it is unnecessary to invoke gas fluidization to explain the mobility of the types of pyroclastic flows examined or the excess runout of large volume debris avalanches

vegetation and climate from two oligocene glacioeustatic sedimentary cycles 31 and 24 ma cored by the cape roberts project victoria land basin antarctica abstract the cape roberts project recovered over 1500 m of coastal glaciomarine sediments of oligocene and early miocene age off the ross sea margin of antarctica the strata are characterised by cyclic repetition of facies in a glaciomarine setting and are interpreted to be a record of glacial interglacial episodes involving significant changes in eustatic sea level on milankovitch frequencies we have undertaken a detailed study of pollen and spores miospores from an early oligocene 31 ma and a late oligocene 24 ma cycle although miospores are sparse in the core averaging only 1 grain per gram of sediment processed over 1200 cenozoic miospores were recovered for this study previous studies of miospores from ross sea sediments have encountered problems differentiating between reworked and in situ palynomorphs here only samples containing a low relative abundance of an eocene dinoflagellate cyst assemblage the transantarctic flora have been used to infer the contemporaneous oligocene miospore flora the flora of the early oligocene cycle is dominated by three species of nothofagidites and four types of podocarpidites the assemblage from the upper oligocene cycle is also dominated by nothofagidites and podocarpidites but with the addition of two distinctive taxa an angiosperm pollen and a bryophyte spore notwithstanding these additions there is a slight decrease in floral diversity between the two cycles while this study confirms that some floristic changes did occur between early and late oligocene time on the victoria land coast the present data suggest that the changes were not extensive it is likely that the vegetation of both cycles was a low diversity scrub of low stature consisting of mainly nothofagus podocarps and bryophytes modern analogues suggest that this vegetation was growing in a climate significantly warmer mean summer monthly temperature 4 12 c than is found on the present day victoria land msmt 5 c although colder that the temperate climate suggested by the diverse flora found in ross sea sediments of eocene age

cenozoic marine sedimentation and ice volume variation on the east antarctic craton recycled cretaceous and cenozoic marine microfossils have been recovered from samples of the pliocene sinus formation samples were collected from outcrops in the reedy beardmore and ferrar glacier areas of the transantarctic mountains between lat 77 and 86 s the glaciogene sediments contained diatoms foraminifera calcareous nannoplankton silicoflagellates radiolarians sponge spicules palynomorphs and ostracodes of late cretaceous paleocene eocene late oligocene late miocene and pliocene age this suggests the presence of open marine basins on the east antarctic craton during late mesozoic and cenozoic time the apparent absence of early oligocene and early through middle and earliest late miocene assemblages suggests either that marine regression exposed the basin floors or that ice filled the basins during these times the high elevation setting of sirius formation outcrops suggests one of two hypotheses for their origin 1 they are in situ pliocene glaciomarine deposits that were uplifted 1 750 2 500 m with the transantarctic mountains to their present elevation 2 the sirius formation deposits are a mixture of derived sediments stripped from sub ice intracratonic basins and subsequently redeposited by ice flowing up the inland slope of the transantarctic mountains we favor the second hypothesis with transport to sites sometime within the past 3 m y

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

new interpretations of the facies of the rhenish brown coal of west germany abstract new ideas concerning the understanding of the facies of the rhenish brown coal of west germany are discussed these new interpretations are based on a significantly larger number of samples and refined procedures for analysis within the field of paleobotany palynology coal petrology and organic geochemistry than were available to p w thomson and m teichmuller the light and dark bands in the coal are mainly the result of different degrees of plant decomposition the influence of the peat forming plant communities plays a subordinate role in the petrographical composition of these particular strata of the rhenish brown coal

pliocene pleistocene diatoms in paleozoic and mesozoic sedimentary and igneous rocks from antarctica a sirius problem solved there are two competing scenarios on the behavior of the east antarctic ice sheet during the late tertiary in one scenario the ice sheet was very dynamic and underwent major drawdown and renewal as late as the pliocene in the other the ice sheet was relatively stable during the late neogene the presence of marine diatoms in sirius group sedimentary rocks in east antarctica is at the center of the disagreement one side regards the diatoms as the major piece of evidence to support the drawdown and renewal hypothesis and infers that they were introduced into the sirius during renewed glaciation of east antarctica others suggest that these diatoms were likely introduced into the sirius by atmospheric largely eolian processes we propose a simple test of the eolian hypothesis if diatoms were introduced into the sirius by eolian processes then they should also be present in older paleozoic and mesozoic sedimentary and igneous rocks samples from two units of the beacon supergroup devonian to jurassic from beacon valley east antarctica were analyzed the beacon heights orthoquartzite devonian and the feather conglomerate permian triassic also examined was sediment found in cracks of paleozoic and mesozoic devonian to cretaceous igneous rocks from marie byrd land west antarctica largely pliocene pleistocene planktonic marine diatoms were found in all sample sets because neither beacon supergroup sedimentary rocks nor igneous rocks from marie byrd land are pliocene pleistocene in age such findings strongly suggest that diatoms were introduced into them by eolian processes this same scenario can be applied to sirius group sedimentary rocks

can dispersive pressure cause inverse grading in grain flows grain flows in the collisional regime are self regulated in such a way that dispersive pressure at every level tends to balance static pressure and so cannot promote the upward segregation of large particles in a steady flow le roux adds new insights to this analysis by pointing out that dispersive and static pressures would not balance in unsteady flows when shear strain rate increases in a grain flow dispersive pressure which is positively correlated to shear strain rate increases too and the gradient of dispersive pressure becomes higher than the gradient of static pressure as a consequence the grain flow expands thus lowering the dispersive pressure until the two gradients reequilibrate during the

potential antarctic ice sheet retreat driven by hydrofracturing and ice cliff failure abstract geological data indicate that global mean sea level has fluctuated on 103 to 106 yr time scales during the last 25 million years at times reaching 20 m or more above modern if correct this implies substantial variations in the size of the east antarctic ice sheet eais however most climate and ice sheet models have not been able to simulate significant eais retreat from continental size given that atmospheric co2 levels were relatively low throughout this period here we use a continental ice sheet model to show that mechanisms based on recent observations and analysis have the potential to resolve this model data conflict in response to atmospheric and ocean temperatures typical of past warm periods floating ice shelves may be drastically reduced or removed completely by increased oceanic melting and by hydrofracturing due to surface melt draining into crevasses ice at deep grounding lines may be weakened by hydrofracturing and reduced buttressing and may fail structurally if stresses exceed the ice yield strength producing rapid retreat incorporating these mechanisms in our ice sheet model accelerates the expected collapse of the west antarctic ice sheet to decadal time scales and also causes retreat into major east antarctic subglacial basins producing 17 m global sea level rise within a few thousand years the mechanisms are highly parameterized and should be tested by further process studies but if accurate they offer one explanation for past sea level high stands and suggest that antarctica may be more vulnerable to warm climates than in most previous studies

the last forests on antarctica reconstructing flora and temperature from the neogene sirius group transantarctic mountains abstract fossil bearing deposits in the transantarctic mountains antarctica indicate that despite the cold nature of the continent s climate a tundra ecosystem grew during periods of ice sheet retreat in the mid to late neogene 17 2 5 ma 480 km from the south pole to date palaeotemperature reconstruction has been based only on biological ranges thereby calling for a geochemical approach to understanding continental climate and environment there is contradictory evidence in the fossil record as to whether this flora was mixed angiosperm conifer vegetation or whether by this point conifers had disappeared from the continent in order to address these questions we have analysed for the first time in sediments of this age plant and bacterial biomarkers in terrestrial sediments from the transantarctic mountains to reconstruct past temperature and vegetation during a period of east antarctic ice sheet retreat from tetraether lipids mbt cbt palaeothermometer we conclude that the mean continental summer temperature was ca 5 c in agreement with previous reconstructions this was warm enough to have allowed woody vegetation to survive and reproduce even during the austral winter biomarkers from vascular plants indicate a low diversity and spatially variable flora consisting of higher plants moss and algal mats growing in microenvironments in a glacial outwash system abietane type compounds were abundant in some samples indicating that conifers most likely podocarpaceae grew on the antarctic continent well into the neogene this is supported by the palynological record but not the macrofossil record for the continent and has implications for the evolution of vegetation on antarctica

self organization in the rapid flow of granular material evidence for a major flow mechanism based on the assumption that high speed high concentration sediment mass flows are primarily granular flows their dynamic properties were studied such highly sheared granular flows are characterized by interparticle collisions this so called rapid granular flow regime has been analysed using two dimensional computer simulations it is shown that granular flows at the microstructural level are governed by deterministic chaos the bulk behaviour is characterized by self organization and an attractor controlling the energy dissipation of the flow the existence of this rapid granular flow attractor easily explains the linear relation between drop height and travel distance of debris flows a compelling consequence of the attractor is that rapid granular flow is the major flow regime in debris flows

petrography and depositional conditions of the 64 65 coal seam in the intrasudetic basin sw poland abstract variation in petrological composition of the coal of the 64 65 seam has been studied two types of vertical lithotype succession were distinguished the first type is represented by bright lithotypes interlayered with clastic partings while the second one shows a succession of lithotypes from bright to dull between clastic partings the occurrence of these two types is believed to be the result of a different rate of subsidence a trend of upward decreasing vitrinite content has been observed in the seam with the second type of the vertical succession this pattern was frequently interrupted by clastic partings this tendency was not developed in the seam of the first succession type on the basis of microlithotype and maceral composition it is found that the 64 65 seam represents a wide range of peat forming environments from telmatic forest moor to open moor almost all bright banded and banded coals were deposited in telmatic forest moor facies while dull banded coal depending upon its petrographic composition represents telmatic forest moor telmatic reed moor limno telmatic forest moor and limno telmatic reed moor dull coal represents only an open moor environment facial analysis of clastic sediments surrounding the seam revealed that there was a relationship between coal and clastic sedimentation the features of the seam are strongly related to sub peat topography distance from active distributaries and stability of the area sulfur and ash contents as well as character of clastic partings and petrology of the seam suggest conditions typical for groundwater and surface dominated swamps with ph a little higher than 4

biomarkers of holocene buried conifer logs from bella coola and north vancouver british columbia canada abstract the biomarker compositions of a holocene seep oil liquefied resin originating from a buried log of douglas fir pseudotsuga menziesii from bella coola bc canada and a holocene pine wood pinus sp sample from north vancouver bc canada were analyzed using gas chromatography mass spectrometry gc ms the total extract of the bella coola sample contains the sesquiterpenoid derivative calamenene and diterpenoids of the labdane abietane pimarane and phyllocladane classes a novel series of successively degraded labdane derivatives labdan 15 oic acid norlabdanoic acids drimenoic acid was detected in the polar fraction and a diagenetic pathway is proposed aromatic abietanes are the major components in the neutral fraction the neutral fraction of the pine wood contains two sesquiterpenoids calamenene cadalene diterpenoids of the abietane pimarane isopimarane and kaurane classes and a series of steroids 18 norabieta 8 11 13 triene dehydroabietin is the major component among the predominantly aromatic abietanes based on the compositions of the terpenoids it is concluded that the diagenesis of the pine and douglas fir logs probably occurred under anaerobic conditions leading to reductive reactions such as decarboxylation of resin acids with concurrent oxidation reactions to form the aromatic derivatives

simply pyroclastic currents gravity driven ground hugging gas pyroclast mixtures produced during explosive volcanic eruptions define a full spectrum of particle concentration flow regime and particle support mechanisms to describe these phenomena the term pyroclastic density current pdc has become increasingly popular in the last few tens of years here i question the general application of the term pdc to the whole flow spectrum and instead i propose the simpler term pyroclastic current

fossil weevils coleoptera curculionidae from latitude 85 s antarctica two species of fossil listroderine weevils coleoptera curculionidae rhytirhinini listroderina are reported from the meyer desert formation at a locality on the beardmore glacier in the transantarctic mountains about 500 km from the south pole associated fossils include wood leaves and pollen of nothofagus stems and leaves of several species of mosses achenes of ranunculus shells of freshwater molluscs and a fish tooth the age of the fossiliferous strata is contentious but probably within the range of pliocene to mid miocene the fossils represent organisms that colonised the margins of a glacier at the head of a fjord during an interglaciation the autecology of the listroderine species indicates that temperatures during summer months averaged 5 c the mean annual temperature with winter temperatures constrained by 6 months of darkness is estimated to have been about 38 c compared to the 326 c estimated for sea level at latitude 85 s today the closest evolutionary link of the fossil listroderines is with south american rather than australian or new zealand taxa divergence of the taxa at least at the level of tribe had most probably occurred on gondwana before the continent broke apart the fossil species are considered to be the descendants of antarctic lineages which evolved on the continent in the late cretaceous or palaeogene and survived until the neogene extinction of the listroderines and most other antarctic terrestrial biota occurred with the growth of the polar ice sheets and the change to the polar desert climate 9 2003 elsevier science b v all rights reserved

cyclic terpenoids of contemporary resinous plant detritus and of fossil woods ambers and coals abstract cyclic terpenoids present in the solvent extractable material of fossil woods ambers and brown coals have been analyzed the sample series chosen consisted of wood remains preserved in holocene to jurassic sediments and a set of of ambers from the philippines copalite israel canada and dominican republic the brown coals selected were from the fortuna garsdorf mine and miocene formations on fiji the fossil wood extracts contained dominant diterpenoid or sesquiterpenoid skeletons and aromatized species were present at high concentrations with a major amount of two ring aromatic compounds tricyclic diterpenoids were the predominant compounds in the ambers aromatized derivatives were the major components consisting of one or two aromatic ring species with the abietane and occasionally pimarane skeletons the saturated structures were comprised primarily of the abietane and pimarane skeletons having from three to five carbon c1 c2 etc substituents kaurane and phyllocladane isomers were present in only minor amounts bicyclic sesquiterpenoids as saturated and partial or fully aromatized forms were also common in these samples but only traces of sesterterpenoids and triterpenoid derivatives were found the brown coal extracts were composed of major amounts of one and two ring aromatized terpenoids with a greater proportion of triterpenoid derivatives than in the case of the woods and ambers this was especially noticeable for the german coal where the triterpenoids were predominant open c ring aromatized structures were also present in this coal steroid compounds were not detectable but some hopanes were found as minor components in the german brown coal an overview of the skeletal structure classes identified in each sample as well as the general mass spectrometric characteristics of the unknown compounds are included in the present paper it can be concluded from these structural distributions that aromatization is the main process for the transformation of terrestrial cyclic terpenoids during diagenesis constituting a general pathway for all terpenoids

a marine and terrestrial sirius group succession middle beardmore glacier queen alexandra range transantarctic mountains antarctica a succession of sirius group glacigene sediments which crop out along the western margins of the beardmore valley between cherry icefall and hewson glacier below the cloudmaker is designated as the stratotype of the cloudmaker formation this new formation overlies a multiply glaciated pavement dominion erosion surface cut into the precambrian goldie formation and is disconformably overlain by the meyer desert formation sirius group the cloudmaker formation comprises bedded and massive diamictons bedded sands and silts and laminated clays assemblages of foraminifera occur throughout the cloudmaker formation and indicate that these basal sirius group sediments were deposited in brackish glacial marine environments the general absence of diatoms suggest these marine waters were ice covered similar marine assemblages are also present in basal sirius group sediments at oliver bluffs dominion range recycled marine diatom assemblages in the sirius group at the latter locality indicate that the host sediments have an age of 3 8 ma pliocene the cloudmaker formation is placed in the pliocene although a latest miocene age for the basal sediments cannot be ruled out stratigraphie sedimentologic and paleontologic evidence suggests that beardmore valley was occupied by a fjord and tidewater glacier system that extended at least 165 km through the transantarctic mountains from the southwestern ross sea the stratigraphy of the cloudmaker formation consists of a succession of members separated by disconformities it is hypothesised that these strata were deposited by a dynamic valley glacier system that underwent a history of glacier advance and grounding alternating with glacier retreat and flotation over a marine water column a combination of fjord basin sediment filling and sea level oscillations may also have influenced the pattern of glacier ice advance and retreat within beardmore paleofjord the marine cloudmaker formation is overlain by the terrestrial diamicton dominated meyer desert formation at oliver bluffs the meyer desert formation diamictons are interbedded with fluvial and lacustrine sediments successions that contain in situ vascular plant fossils principally the southern beech nothofagus mosses and beetle remains a magellanic type flora and fauna occupied the coastal margins of the beardmore paleofjord the vertical transition from the basal marine cloudmaker formation to terrestrial meyer desert formation provides a sea level datum that can be used to assess the extent of post sirius group tectonic uplift uplift rates at the cloudmaker section 90 km inland from the transantarctic mountain front or rift shoulder margin in the queen alexandra mountain block are determined to be 429 or 350 m myr this assumes a total uplift of 1331 m for the uppermost marine sediments of the cloudmaker formation and maximum diatom based ages for the sirius group of 3 1 ma or 3 8 ma gross similarities in stratigraphy and interpreted paleoenvironments are apparent between the cloudmaker succession beardmore paleofjord and the upper miocene pliocene successions at the mouth of taylor paleofjord 800 km to the north contrasting present day elevational settings for these two widely separated marine successions indicates the post sirius rate of tectonic uplift for the transantarctic mountains has been significantly greater in the queen alexandra block

constraints on the application of the mbt cbt palaeothermometer at high latitude environments svalbard norway abstract branched glycerol dialkyl glycerol tetraethers gdgts are membrane lipids of unknown bacteria that are ubiquitous in soil and peat two indices based on the distribution of these lipids in soils the cyclization of branched tetraethers cbt and the methylation of branched tetraethers mbt indices have been shown to correlate with soil ph and mean annual air temperature mat and soil ph respectively and can be used to reconstruct mat in palaeoenvironments to verify the extent to which branched gdgts in marine sediments reflect the distribution pattern on land and whether these proxies are applicable for palaeoclimate reconstruction in high latitude environments with a mat of

sedimentological and petrographical characteristics of cretaceous strandplain coals a model for coal accumulation from the north american western interior seaway abstract coal seams formed on many cretaceous wave dominated strandplain sediments in north america are characterized by great lateral continuity tens to hundreds of kilometres substantial thicknesses up to 12 m relatively low ash and sulphur contents the coals formed behind an active shoreline in areas undergoing subsidence due to shale compaction and dewatering the zone of peat accumulation was remote from the shoreline and storm tidal inundations and generally protected from fluvial flooding if the rate of subsidence was too great lakes formed and peat did not accumulate statistical evaluation of petrographic properties by correspondence analysis of the lower cretaceous coals show that the strandplain coals form distinctive petrographic groups that are characterized by relatively low vitrinite contents and high inertinite contents semifusinite and inertodetrinite dominate in the inertinite maceral group liptinite contents are negligible tissue preservation indices and gelification indices indicate for the strandplain coals a forest type paleodepositional environment in which a relatively low water table allowed the accumulation of oxidized and partly oxidized components fusinite and semifusinite significant amounts of detrital components such as inertodetrinite and vitrinite b are diagnostic that some transportation of the organic material took place prior to deposition comparison of coal facies and depositional environments from permian coals of australian show that the lower cretaceous strandplain coals have petrographic similarities to coals that were formed under regressive back barrier conditions in the permian due to differences in nomenclature previously interpreted regressive back barrier environments may be similar to the strandplain environments discussed here

fragmentation transport and deposition of a low grade ignimbrite the citlaltepetl ignimbrite eastern mexico the citlaltepetl ignimbrite records one of the largest explosive events during the holocene activity of citlaltepetl volcano pico de orizaba multiple pyroclastic flow units a fall deposit and some lahar units were emplaced between 8500 9000 y b p as a result of repetitive but discrete explosive events the whole ignimbrite resulted from discrete fluctuations in eruptive intensity that decreased with time the initial pyroclastic flow pulse was by far the most violent and widespread event and its deposits show conspicuous variations in structure and texture that could be associated with different mechanisms of transport and emplacement subpopulation sequential fragmentation transport sft analyses were carried out in order to determine the physical mechanisms that selectively concentrate or remove particles in the moving flows we suggest that lateral and temporal changes in the flow rheology in which fluidization yield strength entrainment of atmospheric air and sedimentation played a dominant role in flow propagation and emplacement may imprint a unique signature in the grain size spectra the lowermost unit of the citlaltepetl ignimbrite can be envisaged by a model in which progressive aggradation near the vent became replaced by en masse emplacement farther outward

aliphatic and aromatic terpenoid biomarkers in cretaceous and paleogene angiosperm fossils from japan abstract the distributions of aliphatic and aromatic terpenoids in cretaceous and paleogene angiosperm fossils from japan were investigated aliphatic a ring degraded oleanane ursane and lupane were found in all samples in addition aliphatic gymnosperm derived diterpenoids were detected in significant quantities aromatic oleanane type triterpenoids were the major components with ursane and lupane type triterpenoids being minor compounds in all angiosperm fossils in a cretaceous gymnosperm fossil major components included aliphatic labdane isopimarane and abietane type diterpenoids aromatic abietane type diterpenoids and chrysene and picene type polyaromatic hydrocarbons pahs trace amounts of oleanane ursane and lupane type triterpenoids were also identified it is likely that the aromatic triterpenoids were introduced to the gymnosperm fossil from the angiosperm derived material in the sediments we defined an angiosperm gymnosperm index al agi as an alternative to the aliphatic triterpenoid diterpenoid ratio proposed in the literature the al agi index may underestimate the angiosperm contribution because the aliphatic angiosperm derived triterpenoids are more readily converted to aromatic counterparts than the diterpenoids during diagenesis an aromatic angiosperm gymnosperm index ar agi can be calculated using aromatic diterpenoids and triterpenoids we suggest that ar agi is best calculated using only the oleanane ursane and lupane type aromatic triterpenoids and that the chrysene and picene type pahs be excluded

lipid biomarker δ13c and plant macrofossil stratigraphy of a scottish montane peat bog over the last two millennia abstract seven horizons of a peat core covering the last 2000 years from moine mhor a blanket bog in the cairngorm mountains scotland have been examined for the carbon number distributions of the long chain hydrocarbon alcohol and acid components using gas chromatography gc and gas chromatography mass spectrometry gc ms compound specific 13 c values for individual n alkanes were obtained using gas chromatography isotope ratio mass spectrometry gc irms the lipid biomarker distributions and the 13 c values have been compared with those of eleven species of living plant dominant at the contemporary surface of the bog the observed lipid stratigraphy shows only partial agreement with that calculated using macrofossil abundance data and the lipid distributions for the living taxa a result which reflects the inherent uncertainties in both the lipid biomarker and the macrofossil approaches to palaeoenvironmental stratigraphy the carbon isotope values for the individual n alkanes of the plants 27 6 to 36 6 and of the peat layers 29 to 31 7 are as expected for the c 3 photosynthetic pathway however the n alkanes from the surface samples were more depleted by 2 in 13 c than those from the rest of the core a negative shift which may in part reflect the shift 1 2 in 13 c estimated for co 2 in a pre industrialised to an industrialised atmosphere

the geology and coal petrology of a miocene lignite profile at meliadi mine katerini greece abstract the present study describes vertical variations in petrographic composition of a miocene lignitebearing succession from the moschopotamus basin greece the lignite beds are described megascopically in terms of lithotypes and microscopically by maceral contents examination of lithotype variations within the seams and the distribution of facies critical macerals such as humotelinite and humodetrinite and the relatively low inertinite contents suggest a formation of the miocene lignites as reed marsh to wet forest type swamps in a lower delta plain depositional setting reflectances measured on the maceral type eu ulminite b range from 0 36 to 0 42 r random placing the meliadi coals into a transition zone from lignite to subbituminous coal

geological constraints on the emplacement mechanism of the parinacota debris avalanche northern chile the holocene parinacota volcanic debris avalanche ca 8 000 years b p is located in the central andes of northern chile the avalanche formed by the sector collapse of a major stratovolcano adjacent to a lake basin in a single catastrophic event the deposit has an estimated volume of ca 6 km3 a run out of over 22 km and covers more than 140 km2 of the surrounding terrain the values of the heim coefficient 0 08 and the ratio a v 2 3 ca 50 where a is the area covered and v the volume of the deposit indicate high mobility of the avalanche debris in transport two avalanche units can be distinguished the lower unit consists mainly of blocks of rhyodacitic lavas and domes and pyroclastic flow deposits and glacial fluvial and lacustrine sediments the upper unit consists of a coarse grained breccia with little matrix largely composed of andesite blocks which are angular with little or no rounding by abrasion the avalanche displays pronounced hummocky topography in which hummock volume and amplitude as well as maximum block size within individual hummocks tends to decrease with transport distance and towards the lateral margins of the avalanche deposit some surfaces of individual breccia blocks are covered by tens to thousands of small scale impact marks indicating that neighbouring blocks were vibrating and colliding without significant shearing motion most of the deformation and shearing was instead accommodated in a basal layer of wet structureless sediments incorporated into the avalanche debris from the inundated lake basin we propose that the ancestral parinacota stratovolcano collapsed because of loading of underlying fluvioglacial and lacustrine sediments the edifice disintegrated during collapse along existing fractures into large rock domains volumes from 10 to greater than 1 106 m3 which were transported with little internal deformation and then fragmented into hummocks of breccia as they were deposited the decrease of hummock volume with distance suggests that material that travelled further broke up and had an initial greater kinetic energy

reconnaissance study of mineral matter and trace elements in greek lignites abstract mineral matter in low temperature ashes major oxides and trace elements were determined for twenty eight selected lignite samples and their respective 1000 c ashes from various locations in greece using x ray diffraction x ray fluorescence spectroscopy and inaa lignites ashed at lower temperature 150 c reveal the presence of quartz feldspars layer silicates pyrite gypsum bassanite and anhydrite in all samples in northwestern greece epirus kozani florina and ptolemais calcite siderite magnesite epsomite hexahydrite jarosite and meta aluminite coexist with the common occurring minerals large variation in the concentration of major constituents in the 1000 c ashes is observed sio 2 varies from 11 98 to 87 72 al 2 o 3 from 4 53 to 23 36 fe 2 o 3 from 3 01 to 39 72 cao from 0 55 to 43 05 mgo from 0 18 to 9 17 and so 3 from 0 02 to 32 72 smaller variations are exhibited by tio 2 na 2 o k 2 o and p 2 o 5 these variations are attributed to the depositional environment high concentrations of pb 548 ppm zn 2991 ppm ba 1520 ppm as 1131 and 1675 ppm mo 565 and 712 ppm w 191 420 ppm and sb 69 ppm are reported in the 1000 c ashes of the selected lignites from serres and drama northern greece samples from another location in northern greece serres yield 5000 ppm u while in drama dipotama u concentration reaches as high as 17 600 ppm the u enrichment of lignites in these locations is attributed to the leaching of this element from the superimposed u bearing volcanic rhyodacitic rocks of oligocene age in southern greece peloponnesus lignite samples from megalopolis xidias drossato and vounargo show high f ranging from 154 to 218 ppm present results indicate that not only the wide variety and combination of elements that can be used to fingerprint lignitic basins but also the possibility of extracting such valuable elements from lignites and their ashes whenever the concentration and economics warrants such an undertaking

reconciling pyroclastic flow and surge the multiphase physics of pyroclastic density currents abstract two end member types of pyroclastic density current are commonly recognized pyroclastic surges are dilute currents in which particles are carried in turbulent suspension and pyroclastic flows are highly concentrated flows we provide scaling relations that unify these end members and derive a segregation mechanism into basal concentrated flow and overriding dilute cloud based on the stokes number s t the stability factor t and the dense dilute condition d d we recognize five types of particle behaviors within a fluid eddy as a function of s t and t 1 particles sediment from the eddy 2 particles are preferentially settled out during the downward motion of the eddy but can be carried during its upward motion 3 particles concentrate on the periphery of the eddy 4 particles settling can be delayed or fast tracked as a function of the eddy spatial distribution and 5 particles remain homogeneously distributed within the eddy we extend these concepts to a fully turbulent flow by using a prototype of kinetic energy distribution within a full eddy spectrum and demonstrate that the presence of different particle sizes leads to the density stratification of the current this stratification may favor particle interactions in the basal part of the flow and d d determines whether the flow is dense or dilute using only intrinsic characteristics of the current our model explains the discontinuous features between pyroclastic flows and surges while conserving the concept of a continuous spectrum of density currents

transport and emplacement mechanisms of large volcanic debris avalanches evidence from the northwest sector of cantal volcano france abstract large volcanic debris avalanche vda deposits of miocene age occur within the stratigraphic sequence of cantal stratovolcano central france the vda of cantal volcano were initiated by sector collapse of a cone of high elevation up to 4500 m a s l two distinct superimposed vda deposit units breccias i and ii resulted from at least two successive large scale collapse events during the evolution of the volcanic complex breccia i the oldest one is very thick up to 200 m and heterolithologic it is overlain by breccia ii which is thinner up to 50 m and contains more heterometric clasts ranging from hectometer to millimeter size the vda deposits are poorly sorted clasts are angular and highly fractured at different scales often with jigsaw fit in breccia ii jigsaw megaclasts have usually subspheric shapes with size decreasing distally basal deposits commonly display thin inversely graded layers reorientated clasts along ramp structures and cataclasis of the substratum some units have a distal fabric in the form of a poorly developed clast imbrication the clasts are commonly sub rounded thereby indicating abrasion during viscous flow anisotropy of magnetic susceptibility a m s measurements indicate absence of a preferentially oriented matrix fabric magnetic foliation parallel to the bedding suggests that the depositional process is dominated by particle settling the magnetic fabric is better organized in distal deposits where magnetic carriers are imbricated moreover the fragmented clasts and megaclasts are not abraded rather inflation led to isotropic spherical dispersion of clastic material isotropic dispersive inflation which fed the interclast matrix this is also confirmed by the lack of rotation at the individual crystal level all these data strongly suggest transport of vda by liquified non turbulent granular flows distally imbricated deposits suggest more turbulent flow emplacement of the vda results from progressive upward aggradation of the particles by volume reduction and deflation loss the non turbulent liquified stage of the vda disappears the vda behaves as a sliding rigid mass plug flow that exerts strong friction on the basement leading to gouge formation

origin and sedimentary fate of plant derived terpenoids in a small river catchment and implications for terpenoids as quantitative paleovegetation proxies abstract tricyclic diterpenoids and non steroid or non hopanoid pentacyclic triterpenoids are almost exclusively taxon specific terrestrial plant biomarkers produced by conifers and angiosperms respectively due to this source specificity and their prevalence in the geologic record these compounds are often used to reconstruct paleovegetation however the physical and chemical processes that influence the dispersal and fate of terpenoids in sedimentary archives are poorly constrained modern fluvial systems can be used as ancient river analogs to provide information on the utility of terrestrial plant terpenoids as paleovegetation proxies by defining their potential flux and identifying the processes that control their transport to and deposition and degradation in sediments to determine if the contribution of terpenoids from vegetation is reflected in forested soil and river sediments and to constrain the dispersal of these compounds in fluvial systems di and triterpenoid concentrations in miners river drainage basin upper peninsula of michigan usa were quantified in the basin evergreen conifers are less abundant than deciduous angiosperms but yet contribute substantially more terpenoids to soils and river sediments when scaled for leaf litter production and present vegetation cover the composition and relative concentration of di and triterpenoids in source vegetation do not match those in soils and river sediments suggesting that some process or processes result in the preferential removal of diterpenoids while the soil and river sediment terpenoid concentration corrected for differential terpenoid inputs can closely predict the basin wide vegetation cover in miners river drainage basin the extent to which terpenoids can be used a paleovegetation proxy in other modern or geologic sediments remains unclear

conifer and angiosperm biomarkers in clay sediments and fossil plants from the miocene clarkia formation idaho usa the aliphatic lipids and terpenoids of conifer and angiosperm macrofossils and the clay sediment from a new site p 37 of the miocene clarkia formation idaho usa were analyzed to evaluate the preservation of characteristic conifer and angiosperm biomarkers in the sediment series of aliphatic lipids terpenoids and steroids similar to the biomarkers found in type locality clarkia p 33 were the predominant compounds in the sediment and in the fossils long chain aliphatic lipids were major compounds in the fossil plants and the sediment but a differentiation of angiosperm and conifer sources is not possible due to their common distribution among all vascular plants in addition to previously reported terpenoids diterpenoids of a conifer origin and several angiosperm derived polar triterpenoids of the oleanane lupane ursane and friedelane classes are reported here for the first time from the clarkia sediments the conifer shoots taxodium glyptostrobus calocedrus contained characteristic conifer biomarkers such as abietane type diterpenoids while characteristic angiosperm triterpenoids were predominant in the angiosperm leaves betula quercus lithocarpus the biomarker compositions of the taxodium and glyptostrobus shoots match the terpenoid patterns previously reported from fossil seed cones of the same genera although conifer macrofossils contribute about 45 to the flora of site p 37 characteristic conifer biomarkers occurred in the sediment in only low amounts while the angiosperm derived triterpenoids were present in comparatively higher abundances the results indicate that the conifers are under represented compared to the angiosperms according to the terpenoid composition of the sediment extract this may be due to the presence of small angiosperm derived particles leaf detritus wax in the sediment and or migration of leaf waxes from the angiosperm leaves into the sediment in contrast the diterpenoids are trapped in the resinous woody tissue of the conifers and are thus disseminated less into the sediment

signatures of divergence and self organization in soils and weathering profiles abstract complex system behaviors such as self organization are difficult to address in geology system evolution often cannot be directly observed and in geology models and theory must be reconciled with field evidence however self organization can be addressed within the historical interpretive paradigm by applying a measure of the degree of self organization of geologic features using standard interpretive methods to determine the nature of changes and determining whether those changes result in an increase or decrease in organization in this way stable non self organizing convergent development can be distinguished from unstable chaotic self organizing divergent development kolmogorov entropy k entropy was used as a measure of the self organization of soil profiles in eastern north carolina in general the profiles are low in k entropy indicating a generally high level of predictability and information in the vertical arrangement of pedogenetic horizons as a broad generality the study p

three types of pyroclastic currents and their deposits examples from the vulsini volcanoes italy abstract this paper deals with ground hugging gas pyroclast currents from explosive volcanic eruptions and their deposits key field observations and laboratory determinations are proposed to relate specific deposit types with flow regimes and particle concentration in the transport and depositional systems three relevant flow scenarios and corresponding deposit types have been recognized from a survey of pyroclastic successions of the vulsini volcanic district central italy 1 dilute turbulent pyroclastic currents producing normally or multiply graded beds by direct suspension sedimentation 2 concentrated bedload regions beneath suspension currents depositing inversely graded beds by traction carpet sedimentation 3 self sustained high particle concentration laminar mass flows developing massive poorly sorted bodies with opposite grading of coarse lithic and pumice clasts overlying fine grained inversely graded basal layers main distinguishing criteria include the occurrence and pattern of clast grading clast thickness relationships grain size ash matrix componentry and pyroclast size density relationships downcurrent and temporal transitions among identified flow scenarios are likely to occur for changing energy conditions and gas pyroclast ratio both on regional and local scales the nature and efficiency of magma fragmentation volatile content conduit geometry which determine the characteristics of the erupted mixture and possible lateral blast component at the vent and the angle of incidence of the column collapse are suggested as the main factors controlling the generation of one type over the other at flow inception dilute fine grained overpressured eruption clouds are thought to favor the formation of low particle concentration turbulent currents column collapse over slightly inclined volcano slopes causing a high degree of compression of the collapsing mixture and of gas expulsion would favor the generation of high particle concentration pyroclastic currents

new grounds for reassessing palaeoclimate of the sirius group antarctica fossil nothofagus leaves from the meyer desert formation of the sirius group in the central transantarctic mountains have been found with recycled marine diatoms indicating that they are no older than 4 1 3 1 ma they have been interpreted as evidence for pliocene warming and diminution of the east antarctic ice cap in contrast plio pleistocene ice cap stability and sustained polar palaeoclimate has been argued from landforms in victoria land and isotopic data from the southern ocean new evidence on this question comes from fossil soils in the meyer desert formation one of these the siesta palaeosol has a gypsic horizon at a depth of 85 cm as in soils of polar deserts with a mean annual precipitation map of 120 220 mm clastic dykes from a 60 80 cm thick permafrost active layer in the palaeosols are evidence of a mean annual temperature mat of 3 to 11 c this is warmer and wetter than the dominion range today map 36 mm mat 39 c but still a periglacial climate cooler and drier than southern chilean moorland and krummholz map 600 7500 mm mat 5 8 c or subantarctic tundra map 400 2500 mm mat 5 to 5 c a pliocene age for the nothofagus fossils and siesta palaeosol is compatible with soil development on surfaces that bracket their enclosing deposits the dominion range was significantly warmer and wetter than it is today during pliocene c 3 5 ma growth of nothofagus and formation of the siesta palaeosol but the beardmore glacier was still large at that time surface soils and palaeosols of the meyer desert formation are evidence of another warmer and wetter episode earlier during the pliocene c 5 ma both warm intervals were separated by intervening times of glacial expansion and frigid palaeoclimate

erosion transport and segregation of pumice and lithic clasts in pyroclastic flows inferred from ignimbrite at lascar volcano chile abstract investigations have been made on the distribution of pumice and lithic clasts in the lithic rich soncor ignimbrite 26 5 ka and the 1993 pumice flow deposits of lascar volcano chile the soncor ignimbrite shows three main lithofacies which grade into one another coarse lithic breccias range from matrix poor stratified varieties irregular shaped sheets and elongate hummocks in proximal environments to breccia lenses with pumiceous ignimbrite matrix massive lithic rich facies comprise the bulk of the ignimbrite pumice rich facies are bimodal with abundant large pumice clasts often with reverse grading rare lithic clasts and occur distally and on high ground adjacent to deep proximal valleys in the 1993 pyroclastic flow deposits lithic rich facies are deposited on slopes up to 14 whereas pumice rich facies are deposited only on slopes

particle fabric in a small type 2 ignimbrite flow unit laacher see germany and implications for emplacement dynamics ignimbrites of the 13 ka upper laacher see tephra were deposited from small highly concentrated moderately fluidized pyroclastic flows their unconsolidated nature and the prominence of accidental devonian slate fragments make these ignimbrites ideal for clast fabric studies the upper flow unit of ignimbrite m14 has characteristics typical of a type 2 ignimbrite layer 2a and the lower part of layer 2b of the flow unit have strong upstream inclined a p fabrics a p means long particle axes parallel to flow direction only clasts with a b axial ratios of 2 5 or greater preserve good a p fabrics whereas the a b planes of flat fragments dip upstream irrespective of axial ratio the a axis fabric becomes weaker flatter and more girdle like in the upper half of layer 2b at one locality the a axis fabric appears to rotate 40 up through the flow unit suggesting either shear decoupling of different levels in the moving flow or unsteadiness effects in a flow depositing progressively at its base the existence of similarly strong a p fabrics in layer 2a and the lower half of layer 2b appears inconsistent with the common interpretation that ignimbrite flow units are emplaced as a plug of essentially non shearing material layer 2b on a thin shear layer layer 2a and that the entire flow freezes en masse to form the deposit the data suggest that if the flow froze en masse it was shearing pervasively through at least half its thickness another possibility is that the flow unit aggraded progressively from the base up and that the fabrics record the integrated history of shear directions and intensities immediately above the bed throughout the duration of deposition

evolution of cenozoic seaways in the circum antarctic region abstract a complete circum antarctic seaway did not open until both the south tasman rise cleared the oates land coast of east antarctica and drake passage opened between the southern tip of south america and the northern end of the antarctic peninsula major plate motions based on dated seafloor spreading anomalies and distinct fracture zone lineations constrain the age of the opening of a seaway between the south tasman rise and antarctica as very close to the eocene oligocene boundary with an unrestricted opening deeper than 2000 m dating from 32 ma timing of the opening of drake passage is more circumstantial because the exact motions of certain micro continental fragments are not known the motion of africa with respect to south america as well as the motion of east antarctica with respect to africa are well constrained for the cenozoic these major plate motions are used with the reasonable assumption of no cenozoic motion of the antarctic peninsula with respect to east antarctica to constrain the location of the antarctic peninsula with respect to the southern tip of south america for the critical period of late eocene to late oligocene uncertainty of motion of the south georgia and south orkney microcontinents and other possible continental fragments make an exact time for opening of drake passage difficult to ascertain even so the early oligocene position of the antarctic peninsula with respect to south america requires a through going deep water seaway to have been open at drake passage prior to 28 ma even given the unconstrained motion of various high standing crustal fragments in the scotia sea with reasonable assumptions concerning motion of the crustal fragments in the western and central scotia sea it is likely that drake passage or passage through powell basin was open to deep water circulation by 31 2 ma

lipids of aquatic organisms as potential contributors to lacustrine sediments ii abstract the relationship between the lipid composition of organisms in the water column of an eutrophic lake and the lipid composition of underlying sediments previously examined for n alkanols and steroids is now reported for hydrocarbons ketones and carboxylic acids the n c7 alkane and alkenoic acids from two primary sources are rapidly metabolized in the water column and surficial sediment bacterial biomarkers including hopenes and i ai branched fatty acids were detected in the photosynthetic bacterial layer occurring just above the sediment water interface within the sediment the apparent conversion of free n alkanes alkan 2 ones and hydroxy acids to the corresponding bound form is noted microbiological oxidation of n alkanes to alkan 2 ones is supported by the detection of the intermediate alkan 2 ols with a distribution similar to that of the ketones the geochemistry of sediment deposited c 1900 prior to biological study of the site was interpreted from stable biomarkers and the diagenetic changes recognised in the study of contemporary deposition a qualitative difference in algal input to the older sediment is inferred from the low 7 sterol content and presence of 2 6 10 trimethyl 7 3 methylbutyl dodecane however there was still significant dinoflagellate input as indicated by the presence of 4 methylsterols a difference in higher plant input to the older sediment indicated from the n alkane alkene and triterpenoid ketone distributions is consistent with the recent development of tree cover

persistent near tropical warmth on the antarctic continent during the early eocene epoch the warmest global climates of the past 65 million years occurred during the early eocene epoch about 55 to 48 million years ago when the equator to pole temperature gradients were much smaller than today1 2 and atmospheric carbon dioxide levels were in excess of one thousand parts per million by volume3 4 recently the early eocene has received considerable interest because it may provide insight into the response of earth s climate and biosphere to the high atmospheric carbon dioxide levels that are expected in the near future5 as a consequence of unabated anthropogenic carbon emissions4 6 climatic conditions of the early eocene greenhouse world however are poorly constrained in critical regions particularly antarctica here we present a well dated record of early eocene climate on antarctica from an ocean sediment core recovered off the wilkes land coast of east antarctica the information from biotic climate proxies pollen and spores and independent organic geochemical climate proxies indices based on branched tetraether lipids yields quantitative seasonal temperature reconstructions for the early eocene greenhouse world on antarctica we show that the climate in lowland settings along the wilkes land coast at a palaeolatitude of about 70 south supported the growth of highly diverse near tropical forests characterized by mesothermal to megathermal floral elements including palms and bombacoideae notably winters were extremely mild warmer than 10 c and essentially frost free despite polar darkness which provides a critical new constraint for the validation of climate models and for understanding the response of high latitude terrestrial ecosystems to increased carbon dioxide forcing

the occurrence and origin of prominent massive pumice rich ignimbrite lobes within the late pleistocene abrigo ignimbrite tenerife canary islands abstract the 0 196 ma lithic rich abrigo ignimbrite on tenerife canary islands contains localised massive coarse pumice rich ignimbrite lobes mprils they typically form low ridges up to 2 m high with axes parallel to the flow direction and in cross section they range from symmetrical to asymmetrical and highly skewed lobate bedforms generally with flat bases the major components are rounded pebble to cobble sized phonolitic pumice clasts within an ignimbritic matrix of ash fine lithics and minor crystals which varies from lithic rich to lithic poor commonly there is a vertical increase in pumice concentration from matrix supported texture at the base to clast supported at the top accompanied by an increase in pumice clast size mprils often thin and grade laterally perpendicular to current flow into planar pumice concentration zones they occur at one or more stratigraphic levels as either solitary lobes associated with flat topography or as multiple onlapping lobes or within a laterally complex stratified pumice rich ignimbrite facies lcspis near palaeotopographic highs mprils are original depositional features not erosional in origin and are derived from a larger pyroclastic flow it is likely that pumice was segregated to the upper and outer regions of the parent flow causing a significant rheological contrast with the lower lithic rich zone the more pumice rich parts are interpreted to have detached from the parent flow as it decelerated onto gentler slopes or interacted with topographic highs and raced ahead as mobile derivative pyroclastic flows the flow parallel ridge shape of mprils may be a result of fingering within these flows or concentration of pumice within the intermediary clefts deposition occurred en masse at the termination of the flow front the resultant lobate deposits were then overridden and mantled by normal ignimbrite facies from either a later flow pulse or the following main part of the parent flow

latitudinal distribution of terrestrial lipid biomarkers and n alkane compound specific stable carbon isotope ratios in the atmosphere over the western pacific and southern ocean abstract we investigated the latitudinal changes in atmospheric transport of organic matter to the western pacific and southern ocean 27 58 n 64 70 s molecular distributions of lipid compound classes homologous series of c15 to c35 n alkanes c8 to c34 n alkanoic acids c12 to c30 n alkanols and compound specific stable isotopes 13c of c29 and c31 n alkanes were measured in marine aerosol filter samples collected during a cruise by the r v hakuho maru the geographical source areas for each sample were estimated from air mass back trajectory computations concentrations of tc and lipid compound classes were several orders of magnitude lower than observations from urban sites in asia a stronger signature of terrestrial higher plant inputs was apparent in three samples collected under conditions of strong terrestrial winds unresolved complex mixtures ucm showed increasing values in the north pacific highlighting the influence of the plume of polluted air exported from east asia n alkane average chain length acl distribution had two clusters with samples showing a relation to latitude between 28 n and 47 s highest acl values in the tropics whilst a subset of southern samples had anomalously high acl values compound specific carbon isotopic analysis of the c29 25 6 to 34 5 and c31 n alkanes 28 3 to 37 revealed heavier 13c values in the northern latitudes with a transition to lighter values in the southern ocean by comparing the isotopic measurements with back trajectory analysis it was generally possible to discriminate between different source areas the terrestrial vegetation source for a subset of the southernmost southern ocean is enigmatic the back trajectories indicate eastern antarctica as the only intercepted terrestrial source area these samples may represent a southern hemisphere background of well mixed and very long range transported higher plant organic material

pseudotachylyte frictionite at the base of the arequipa volcanic landslide deposit peru implications for emplacement mechanisms abstract the arequipa volcanic landslide deposit peru displays a pseudotachylyte or frictionite at its basal contact with an older ignimbrite the pseudotachylyte consists of a dark 1 cm thick vitreous layer that shows striations on its upper surface it contains small mineral clasts from both the landslide rocks and the underlying ignimbrite embedded in an optically isotropic matrix tem observations revealed a clast melt suspension with a lower black obsidian like vein made of chemically heterogeneous glass the pseudotachylyte is interpreted as the result of partial melting due to frictional heating during landslide emplacement this is the third pseudotachylyte reported at the base of a landslide deposit and the first in a volcanic environment calculations show that basal melting only accounts for a small proportion of the total energy released during landslide emplacement indicating that landslide transport was dominated by dissipative stresses affecting the whole landslide body and not conce

maceral distributions in illinois coals and their paleoenvironmental implications abstract for purposes of assessing the maceral distribution of illinois u s a coals analyses were assembled for 326 face channel and drill core samples from 24 coal members of the pennsylvanian system the inertinite content of coals from the missourian and virgilian series averages 16 1 mineral free compared to 9 4 for older coals from the desmoinesian and older series this indicates there was generally a higher state of oxidation in the peat that formed the younger coals this state probably resulted from greater exposure of these peats to weathering as the climate became drier and the water table lower than was the case for the older coals although oxidation during allochthonous deposition of inertinite components is a genetic factor that needs further study to confirm the importance of the climate regional variation of the vitrinite inertinite ratio v i on a mineral and micrinite free basis was observed in the springfield no 5 and herrin no 6 coal members to be related to the geographical position of paleochannel river deposits known to have been contemporaneous with the peats that formed these two coal strata the v i ratio is highest generally 12 27 in samples from areas adjacent to the channels and lower 5 11 some 10 20 km away we interpret the v i ratio to be an inverse index of the degree of oxidation to which the original peat was exposed high v i ratio coal located near the channels probably formed under more anoxic conditions than did the lower v i ratio coal some distance away from the channels the low v i ratio coal probably formed in areas of the peat swamp where the watertable was generally lower than the channel areas

evidence of pliocene nothofagus in antarctica from pliocene marine sedimentary deposits dsdp site 274 microfossil assemblages in pliocene sediments from dsdp site 274 68 59 81 s 173 25 64 e provide data on the age of the sediments and suggest the presence of nothofagus southern beech in antarctica during the pliocene a suite of 17 samples was collected in an interval from samples 28 274 6r 1 83 87 cm to 28 274 11r 4 73 77 cm 48 33 100 29 mbsf bio stratigraphic study of the abundant diatom assemblages combined with published radiolarian data indicates that the sample interval ranges in age from 5 0 to 2 2 ma with an apparent unconformity between about 3 8 and 3 2 ma nothofagidites the genus for fossil pollen referable to nothofagus occurs throughout the interval as well as pollen and spores with known stratigraphic ranges that unequivocally indicate reworking from older rocks species of nothofagidites recovered include n asperus n brachyspinulosus n flemingii n senectus and n sp cf n lachlaniae the latter form is previously known from the sirius group in the transantarctic mountains abundant palynomorphs were recovered in only three of the samples from site 274 samples 28 274 9r 2 15 19 cm 28 274 9r 2 48 52 cm and 28 274 9r 2 65 69 cm based on the diatom and radiolarian biostratigraphic data the ages of these samples range from 3 00 to 3 01 ma the relative abundance of n sp cf n lachlaniae in the three samples is an order of magnitude higher than relative abundances for the other species of nothofagidites in the same samples the significantly higher relative abundance of n sp cf n lachlaniae suggests that this pollen was derived from trees of nothofagus that were living in antarctica during the mid pliocene diatom assemblages from these three samples indicate that sediments in this interval were rapidly deposited as biogenic oozes in an open ocean setting relatively free of sea ice thus decreasing the possibility of reworking from a single source bed rich in n sp cf n lachlaniae clearly more detailed work in additional well dated cores from around antarctica is needed before a clear picture of the neogene history of antarctic terrestrial vegetation emerges

runout lengths of sturzstroms the control of initial conditions and of fragment dynamics sturzstroms are giant landslides that travel kilometers within minutes data from terrestrial examples of 0 001 10 km3 suggest that their runout lengths increase in proportion to the square root of their volume this trend is investigated assuming that runout is controlled by fragmental flow the results indicate that runout lengths depend on the potential energy available for motion after initial collapse itself a function of the dimensions of the collapse zone on the degree of rock fragmentation and on the rate of momentum loss by fragment collisions in a basal boundary layer assumed to thicken with time by diffusion a dependence on initial conditions during collapse would explain claims that a minimum volume is required for sturzstroms to form beneath a critical volume insufficient energy is available to initiate fragmental flow and so the unstable mass slumps downslope the drop height h is often similar to the vertical extent of the collapse zone and so is linked by geometry to sturzstrom volume the ratio of h to l the horizontal distance of effective transport normally interpreted as a measure of frictional resistance is thus reinterpreted as an inverse measure of the energy available for runout after collapse by providing a physical basis for observed trends the analysis justifies use of empirical limits for forecasting the runout lengths of major landslides

convergent cenozoic co2 history reconstructions of atmospheric carbon dioxide concentrations over the past 65 million years are heading towards consensus it is time for systematic testing of the proxies against measurements and against each other

seasonal variability in arctic temperatures during early eocene time abstract as a deep time analog for today s rapidly warming arctic region early eocene 52 53 ma rock on ellesmere island in canada s high arctic 79 n preserves evidence of lush swamp forests inhabited by turtles alligators primates tapirs and hippo like coryphodon although the rich flora and fauna of the early eocene arctic imply warmer wetter conditions than at present the quantification of eocene arctic climate has been more elusive by analyzing oxygen isotope ratios of biogenic phosphate from mammal fish and turtle fossils from a single locality on central ellesmere island we infer early eocene arctic temperatures including mean annual temperature mat of 8 c mean annual range in temperature of 16 5 19 c warm month mean temperature of 19 20 c and cold month mean temperature of 0 3 5 c our seasonal range in temperature is similar to the range in estimated mat obtained using different proxies in particular relatively high estimates of early eocene arctic mat and sst by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether gdgt membrane lipids in terrestrial soil bacteria and isoprenoid tetraether lipids in marine crenarchaeota fall close to our warm month temperature suggesting a bias towards summer values from a paleontologic perspective our temperature estimates verify that alligators and tortoises by way of nearest living relative based climatic inference are viable paleoclimate proxies for mild above freezing year round temperatures although for both of these reptilian groups past temperature tolerances probably were greater than in living descendants

warm fjords and vegetated landscapes in early pliocene east antarctica abstract the response of the antarctic ice sheets to future warming is uncertain the ipcc are predicting minimal melt from antarctica while others suggest increased meltwater contributions are possible the pliocene period 5 333 ma to 2 58 ma may provide insights into future ice sheet response because atmospheric co2 concentrations were similar to today 350 450 ppmv and the earth surface was between 2 c and 4 c warmer than the preindustrial conditions geological records indicate that antarctica s ice sheets were smaller and more dynamic at this time and many sea level estimates require meltwater input from the greenland west wais and east antarctic ice sheets eais however only a few records exist proximal to the antarctic ice sheet which allow for reconstruction of the pliocene climate state we present a multiproxy climate reconstruction from a sedimentary succession that was deposited in an ancient fjord within the transantarctic mountains covering discrete intervals between the early pliocene and the late pleistocene in contrast to modern frigid conditions our records indicate sea surface temperatures of about 5 6 c at c 4 1 ma the presence of a plant community at the fjord margins and evidence of soil formation simulations of potential vegetation cover in the pliocene indicate our reconstruction is most compatible with a complete collapse of the wais and a large scale retreat of the eais from the subglacial basins with atmospheric co2 levels of less than 450 ppmv our study indicates that under present day atmospheric co2 conditions in the early pliocene the antarctic ice sheets retreated significantly understanding the mechanisms driving this large scale ice sheet retreat would enable us to assess whether current atmospheric co2 concentrations will lead to the same ice sheet configuration once the earth system has come to a new equilibrium state

signatures of tetraether lipids reveal anthropogenic overprinting of natural organic matter in sediments of the thames estuary uk intertidal foreshore sediments from a 110 km stretch of the thames estuary were analysed for glycerol dialkyl glycerol tetraethers gdgts to track soil organic matter om input and evaluate the impact of coastal urbanisation on their distribution concentration of branched br gdgts ranged from 1 to 15 g g organic carbon oc and crenarchaeol ranged from 0 6 to 19 g g oc an overall decrease in brgdgts was observed from the inner thames brentford to the outer thames isle of grain suggesting a drop in soil om input towards the sea in contrast crenarchaeol concentration was highest around east london rather than towards the open sea such elevated crenarchaeol concentration occurred in the section of the river most influenced by anthropogenic pollution such as discharge points for london s major sewage treatment plants docks and power plants the non systematic spatial distribution of crenarchaeol was also reflected in the branched isoprenoid tetraether bit index the highest bit values occurred upstream and in close proximity to salt marshes 0 8 1 whereas the lowest values 0 3 0 5 were towards the sea however unusually low values 0 4 were observed in the river section that had high crenarchaeol concentration in contrast bulk 13c values were insensitive to london s anthropogenic influence this suggests that the natural systematic decrease in bit index in the estuary is overprinted by london s anthropogenic activity between deptford creek and tilbury we therefore advise caution when interpreting the bit index for sediments in close proximity to megacities discharging industrial and municipal waste that can become incorporated into the near surface sedimentary record

a comparison of terpenoid and leaf fossil vegetation proxies in paleocene and eocene bighorn basin sediments abstract plant derived terpenoids long recognized as biomarkers can help reveal the major taxonomic groups of land plants present in ancient environments even if rocks and sediments do not preserve plant macro or microfossils previous studies have used simple di to triterpenoid ratios to reconstruct floral changes in the geologic past but few have compared terpenoid ratios with estimates of floral composition from fossils further reconstructions have not taken into account differences in biomarker production i e concentration relative to leaf biomass between different types of plants here we have examined terpenoids from early cenozoic fluvial rocks from the bighorn basin wyoming usa where fossil flora has been studied in detail we analyzed the distributions of diterpenoids triterpenoids and n alkanes from leaf wax in a total of 43 samples from 15 stratigraphic horizons of late paleocene 63 ma to early eocene 53 ma in age in nearly all samples triterpenoids derived from angiosperms were significantly lower in abundance than conifer specific diterpenoids a finding that contrasted with plant fossil evidence for the same rocks this suggests that di to triterpenoid ratios severely underestimate the abundance of angiosperms in paleovegetation angiosperms dominated n alkane production among modern plants and we propose a new paleovegetation proxy based on the ratio of diterpenoids conifers to n alkanes angiosperms corrected for lipid production estimated from extant vegetation using diterpenoids and alkanes we infer the composition of paleovegetation to be similar to that inferred from plant fossils although the approach works well for the bighorn basin we stress the new paleovegetation proxy will need to be evaluated for other time periods communities paleogeography and depositional environments with pollen or megafossil data available