transitional changes in arborescent lignophytes at the devonian carboniferous boundary abstract it is usually considered that after the extinction of the devonian tree archaeopteri s no new arborescent lignophytes were established before the late tournaisian a reassessment of this pattern is presented here based on a three fold approach a re evaluation of the taxic diversity of tournaisian lignophyte trees based on descriptions of new plants from palaeotropical latitudes a study of the patterns of phenotypic changes occurring among early lignophytes using a principal coordinate analysis and a phylogenetic analysis of the affinities of the arborescent taxa the best supported results indicate that a substantial taxonomic and phenotypic diversity of arborescent lignophytes was already established in the first part of the tournaisian including some taxa that persisted until the serpukhovian two genera may have originated in the late devonian and crossed the devonian carboniferous boundary fewer originations and a decrease in phenotypic diversity occurred in the visean the phenotypic distinctiveness of tree stems compared with those of other growth forms in the lignophytes is assessed we propose a scenario in which the presence of lignophyte trees is continuous across the devonian carboniferous boundary with arborescent taxa distinct from archaeopteris already present in the latest devonian possibly in upland floras and diversifying significantly soon after the devonian carboniferous boundary supplementary material a list of taxa characters and matrices used in the principal coordinate analysis and phylogenetic analysis is available at http www geolsoc org uk sup18447

frasnian plants from the dra valley southern anti atlas morocco anatomically preserved plant fragments are reported from devonian marine deposits exposed in the dra valley of southern anti atlas morocco associated conodont and tentaculite faunas indicate that the sediments yielding plants which consist of black shales with intercalated calcareous concretions are early frasnian in age and most probably represent zone 2 of the conodont zonation this is the first record of frasnian plants in north africa the specimens found all correspond to decorticated portions of axes six are referable to callixylon the organ genus corresponding to anatomically preserved axes of the progymnosperm tree archaeopteris based on wood characters especially ray structure they are assigned to the species c henkei formerly described from the famennian of europe one single specimen is compared to xenocladia a cladoxylopsid genus previously known from the middle devonian of europe usa and kazakhstan interestingly archaeopteridales and cladoxylopsida are two groups that dominate the younger plant assemblages of famennian age recently described from the eastern anti atlas callixylon henkei type axes occur both in the frasnian and in the famennian deposits of the anti atlas and they are all devoid of growth rings these results are in accordance with a close position of gondwana and euramerica during late devonian times

organic matter of the mulhouse basin france a synthesis the lower oligocene evaporite sequence of the mulhouse basin france contains organic matter rich marl deposits these marls display an overall cyclic variation of sedimentation rate organic carbon content hydrogen index and selected molecular parameters over a 30 m thick stratigraphic interval the integration of all sedimentological and geochemical parameters has allowed the reconstruction and characterization of the paleoenvironment of deposition the marls were deposited in a perennial lake that was at times connected to the sea two organic facies end members could be assigned to a lake stage with a marine connection and a lake stage that received dominantly continental water input the overall stratigraphic variation in the organic matter content is interpreted to reflect the adaptation of the oligocene flora to the changing paleoclimate and environmental conditions

stereochemical studies of acyclic isoprenoids xii lipids of methanogenic bacteria and possible contributions to sediments abstract abundant volatile lipids of methanobacterium thermoautotrophicum and methanosarcina barkeri include isoprenoid hydrocarbons c30 and c15 c20 and c25 isoprenoid alcohols m barkeri contains 2 6 10 15 19 pentamethyleicosane whose relative stereochemistry is the same as found in marine sediments indicating that it is a marker of methanogenic activity the c20 c30 and c25 alkenes in m thermoautotrophicum also have a preferred sterochemistry the latter have the 2 6 10 14 18 pentamethyleicosanyl skeleton suggesting that the alkane in marine sediments may derive from methanogens the stereochemistry of squalane in a marine sediment is also compatible with an origin in methanogens in contrast the stereochemistry of pristane in m thermoautotrophicum indicates a fossil fuel contaminant origin suggesting that this and certain other alkanes reported in archaebacteria might also be of contaminant origin there is therefore little evidence at present that the pristane in immature marine sediments originates in methanogens the c15 and c20 saturated alcohols in m thermoautotrophicum have mainly the all r configuration if this is generally true for methanogens the c20 alcohol in the messel shale may originate mainly from methanogens whereas that in the green river shale may originate mainly from photosynthetic organisms

first record of rellimia leclercq bonamo aneurophytales from gondwana with comments on the earliest lignophytes

characterization of organic rich material in an evaporitic environment the lower oligocene of the mulhouse basin alsace france evaporitic sediments from the max borehole mulhouse potash basin southern rhine graben were studied over an interval of about 40 m in the vicinity of sylvite beds total organic carbon toc analyses of 450 samples showed that marly layers interbedded within the evaporites have toc values that fluctuate in a rhythmic manner the highest values are found near the top of the clay anhydrite layers and the lowest values are recorded near the top of the halite rich beds geochemical elemental analysis of kerogen gas chromatography of bitumen and palynological studies of 26 samples showed that the organic matter is mainly of algal origin a and b groups a third category of organic material c group may have been derived from a mixture of continental supply and in situ bacterial productivity

a method for including path effects in ground motion prediction equations an example using the mw 9 0 tohoku earthquake aftershocks past studies in tectonic regions dominated by subduction zones that result in the creation of volcanic belts such as new zealand and japan have pointed to higher attenuation rates across the volcanic regions this study uses the downhole motions recorded at kik net stations from 117 aftershocks that hit japan after the great m w 9 0 tohoku earthquake to quantify region dependent strong motion attenuation rates to this end an approach to include path effects in the development of ground motion prediction equations gmpes is presented in this approach regional path terms are constrained using the strong motion data the constraint on path terms also makes this methodology suitable for the development of gmpes that permit the removal of the ergodic assumption on path the analysis results indicate the viability of the proposed methodology for constraining regional path terms and provide an estimate of single station single path standard deviations in addition results confirm that the attenuation rate in volcanic regions is significantly higher than in nonvolcanic regions finally a moderate correlation coefficient was found between the attenuation rate for weak and strong ground motions

partially nonergodic empirical ground motion models for predicting horizontal and vertical pgv pga and 5 damped linear acceleration response spectra using data from the iranian plateau we present new ground motion prediction equations gmpes to estimate horizontal and vertical strong ground motion intensity measures gmims generated by shallow active crustal earthquakes occurring within the iranian plateau to this end a dataset containing 688 records from 152 earthquakes with moment magnitudes ranging from 4 7 to 7 4 and joyner boore distances up to 250 km has been used the effects of the local site condition are taken into account using the time averaged shear wave velocities in the upper 30 m v s 30 we decided not to include the style of faulting term in the final functional form because the total standard deviation is reduced 10 by removing this term from the functional form we used a nonlinear mixed effects regression to determine the coefficients of the functional form and to separate out the between event and between station standard deviations from the total standard deviation significant standard deviation of site to site variability demonstrates that the ergodic assumption is not able to account for the spatial variability of ground motions we introduced random effects coefficients to capture regional variations between different tectonic regions of the iranian plateau such as alborz and zagros in the regression analysis to investigate the effects of regionalization on gmpes the results showed that although the effects of regional variations for considered regions are negligible at close distances they are significant at longer distances the complexity and performance of the final functional form is justified by comparing akaike and bayesian information criteria values over many trial functional forms moreover the distribution of between event site to site and event station corrected residuals demonstrates that no trends are evident implying satisfactory performance of the proposed gmpes therefore the derived gmpes can be employed to predict gmims and to do seismic hazard assessments within the iranian plateau electronic supplement 1 lists of the events and stations considered in the final dataset and derived coefficients of the functional form 1 http www bssaonline org lookup suppl doi 10 1785 0120160205 dc1

geological and geochemical modeling an approach for understanding organic cyclic sedimentation in evaporitic sequences application to the mulhouse basin france in the upper eocene to lower oligocene mulhouse basin france upper rhine graben an organic rich evaporitic series has been deposited first and second order cyclicities can be defined at the scale of the study a short period cyclicity corresponding to an alternation of marl and evaporitic layers a long period cyclicity corresponding to an evolution of the evaporitic layers from an anhydritic to halitic or sylvitic composition the characteristics and abundance of organic matter in the marl also show cyclic variations in amount and origin a geological scenario based on numerical modeling served for testing relationships between the environmental evolution including state of stratification of the basin sea level change and water balance variations and the organic sedimentation phytoplankton productivity as well as terrestrial organic matter input have been simulated and compared to the organic data the model results account for the distribution of organic matter in the basin and are in agreement with the geological and geochemical data they serve to place the paleo environment elaborated by hofmann et al 1993 within a more dynamic sedimentological framework this work demonstrates the benefit of numerical modeling in tentatively identifying the respective influence of eustasy and climate on the organic sedimentation in an evaporitic basin

seasonal succession and microlamina formation in a meromictic lake displaying varved sediments in a small meromictic lake near toronto canada a mass mortality of photosynthetic bacteria followed the ventilation of the chemocline during fall autumn and resulted in 3 8 g m 2 day 1 of organic matter being deposited as a dark layer in sediment traps which were suspended in the permanently anaerobic zone this mass mortality of photosynthetic bacteria occurred in late autumn following the annual thermal destratification of the lake s mixolimnion wind mixing during this period of homeothermy resulted in the introduction of low levels of dissolved oxygen into the lake s chemocline the ensuing mass mortality of photosynthetic bacteria resulted in the release of elemental sulphur as the sulphur rich bacteria decomposed and sank to the bottom of the lake the ferrous ions in the water below a depth of 15 m in crawford lake reacted with this sulphur to form black ferrous sulphides and pyrite which formed a dark microlamina on the lake floor each dark microlamina was overlain by a light coloured calcite rich layer which was deposited each spring and summer during the 3 yr period of this study the mechanism of microlamina formation elucidated here has been based on the examination of bi weekly sediment trap information this approach has permitted an explanation of the mechanisms by which specific events such as calcite precipitation and phytoplankton seasonal succession are transcribed into the sediment record

evidence for ancient halophiles testing biomarker syngeneity of evaporites from neoproterozoic and cambrian strata molecular fossils from evaporites can provide significant insights into the biotic composition of ancient hypersaline ecosystems however hydrocarbon contamination can mask the true nature of this composition and potentially result in misleading interpretations in this study drill core samples of neoproterozoic and cambrian age dolomite anhydrite and halite from the amadeus basin in central australia contain distinctive and varied hydrocarbon signatures the results are consistent with previous studies of ancient hypersaline settings and include elevated concentrations of heptadecane n c17 docosane n c22 a diverse range of acyclic isoprenoids hopanes and steranes including high concentrations of pregnanes furthermore several samples yielded hydrocarbon signatures with high concentrations of mono and dimethylalkanes relative to n alkanes which is characteristic of many cambrian and precambrian bitumens by quantifying the exterior interior concentration differences of biomarkers in these evaporites considerable insight into the syngeneity of these molecules was obtained in most samples the majority of biomarkers were only detected in the exterior demonstrating that they are contaminants and not indigenous to the evaporites these include biomarkers typically assigned to hypersaline environments demonstrating in this case that their presence is not necessarily an indicator of syngeneity we show that even in combination these molecules can have a wide variety of sources that are not necessarily indigenous to the host rocks nevertheless some neoproterozoic evaporites while also marred by contamination contain demonstrably indigenous biomarkers with equal concentrations on the rock exterior and interior we show that the ability to discern biomarker syngeneity in a complex mix of contaminated and indigenous hydrocarbons requires the need for each compound in every sample to be separately evaluated this study provides an example of how to unravel such a complex series of contamination and obtain more accurate insights into biomarkers of ancient evaporites the approach outlined herein can be readily applied to biomarker studies of other ancient settings

age constraint for an earliest famennian forest and its implications for frasnian famennian boundary in west junggar northwest china abstract as one of the five major extinction events in earth history the frasnian famennian boundary ffb crisis caused dramatic reductions in marine and terrestrial diversity the effects of this event on terrestrial ecosystems are not well understood due to the limited preservation of terrestrial sedimentary rocks and the relative scarcity of plant fossils this study generates a robust zircon u pb age 371 5 0 9 ma earliest famennian for a new fossil assemblage containing lycopsida archaeopteridales and cladoxylopsida from the upper zhulumute formation of the west junggar basin nw china these taxa are typical arborescent plants of the late devonian and represent the oldest known forest in china documenting afforestation in west junggar coevally with or just after the upper kellwasser event 372 ma the new u pb ages generated in this study refine the placement of the ffb in west junggar to within the zhulumute formation instead of the hongguleleng formation as previously thought

wood taphonomy in a tropical marine carbonate environment experimental results from lee stocking island bahamas abstract both teredinid bivales and limnorid isopods attacked wood that was deployed experimentally for two years in a carbonate environment on average wood samples collected after one year on the sea floor lost 17 of their original surface area to limnoria and 50 of their original volume to teredinids after two years on the sea floor wood samples lost an average of 39 of their original surface and 74 of their original volume all samples of kiln dried lumber pinus sequoia araucaria magnolia and quercus experienced significantly more attack by teredinids and limnoria than samples of quercus stellata post oak branch wood that experienced terrestrial decomposition in a warm temperate environment for five years before deployment on the sea floor taphonomic loss rates for wood in marine environments based on kiln dried lumber may overestimate loss rates for natural wood entering marine environments after initial decomposition in terrestrial environments burial appears to play an important role in wood taphonomy burial to a depth of 3 cm inhibited destruction by limnoria but not teredinids possibly due to the greater tolerance of molluscs for low o 2 levels and the ability of teredinids to raise their siphons above the wood surface both limnorids and teredinids may contribute to the formation of teredolites disaggregated sediment filled teredinid borings limnorid isopods remove the surface of wood exposing the calcite lined borings of teredinids once their calcite lined borings are exposed teredinid are susceptible to predation and in the aftermath of predation teredinid borings may become sediment filled exposure also causes the calcite lined borings to break and disaggregate leading to the formation of teredolites the fossil record of teredinids reaches back to the jurassic limnoria traces in the surface of wood are distinctive and diagnostic at the species level however limnoria have a sparse fossil record

application of biological markers in the recognition of palaeohypersaline environments the hydrocarbon fractions of a marl sample from a messinian basin in the northern appenines and four oils rozel point oil utah and three seep oils from sicily were studied

microanalysis of primary fluid inclusions in halite constraints for an evaporitic sedimentation modeling application to the mulhouse basin france the chemistry of the waters from which the evaporitic minerals crystallized in the lower part of the salt iv unit of the mulhouse basin france has been investigated the lithological and fluid inclusion data have been compared to the output data of the mass transfer program newequi which simulates the change in brine composition during its evaporation advancement the results show that the evolution of the composition of the brine is compatible with the calculated sequence of evaporation of a parent water corresponding to a seawater modified by cacl2 rich hydrothermal water in the studied sequence fluid inclusion data provide useful constraints for reconstructing the paleoenvironment controlling the evaporitic sedimentation they also provide data on the water stratification in the basin and on its connectivity with the open sea and important parameters controlling the productivity possible sources for the nutrients and the preservation of organic matter in the sediment

the mesozoic cenozoic tectonic settings paleogeography and evaporitic sedimentation of tethyan blocks within china implications for potash formation abstract potash deposits are common in the mesozoic cenozoic tethyan domain which features the giant potash deposits in the late jurassic central asian basin and the late cretaceous khorat basin of thailand laos widespread evaporitic sequences from these intervals have been found in some marine and transitional basins within the chinese continental blocks such as the yangtze simao and tarim blocks in which only one small scale potash deposit had been found in the late cretaceous simao basin these evaporites are commonly characterized by depositional cycles that are more frequent than those of other potash basins around the world it remains debated whether large or giant potash deposits could be formed in chinese blocks of tethyan domain and if so what mechanism was responsible for the potash formation to address these issues we comprehensively review the meso cenozoic drift history and collision dynamics of these chinese blocks and summarize the formation mechanism depositional characteristics and paleoclimate of the evaporite basins in these blocks these blocks drifted from the southern hemisphere and collided and welded together in the beginning of the late permian in the northern hemisphere the collisions often commenced in the east and gradually spread to the west of these blocks resulting in 1 westward seawater retreat 2 differential topographic uplift with high topography in the east and low topography in the west and 3 increasingly closed depositional environments in these basins in addition these collisions often exerted nearly n s oriented principal compressive stress which resulted in nearly e w oriented extension these forces induced a series of faulted bounded subsidence belts with n s striking extensional sub basins arranged in an e w oriented chain in these blocks in this chain like sub basins system as sea level rose and seawater flowed from west to east the western sub basins proximal to the open sea would have precipitated calcium carbonates and calcium sulfates resulting in a high degree of concentration by the time the brines reached the distal end i e eastern sub basins ultimately potash minerals were commonly deposited in the easternmost sub basins based on the above model of potash formation we predict that potash deposits may be formed in certain sub basins in the eastern part of these basins in chinese tethyan blocks which maybe lay a theoretical foundation for china s future exploration of potash deposits

between event variance for large repeating earthquakes we estimate the variance in ground motions related to repeated large earthquakes occurring on the same fault segment with similar magnitudes we find eight earthquake pairs for which suitable strong motion records exist two are crustal strike slip earthquakes from california and six are subduction zone earthquakes from japan we consider only large earthquakes and deal with frequencies greater than the earthquake corner frequency so the variability that is considered here is related to smaller scale differences in the rupture process particularly on the part of the fault nearest the station we find that the variance of the 5 damped spectral accelerations of these pairs termed graphic 1 averages to about 45 and 80 of 2 for the crustal and subduction zone earthquakes respectively in which 2 is the contribution of source variability to the total variability of ground motion estimated by some recent ground motion prediction equations we suggest that graphic 2 is lower than 2 for the frequencies at which graphic 3 is estimated because it depends primarily on only local physical properties of a fault that are the same in repeated earthquakes we therefore suggest that at sites where the hazard is controlled by a single rerupturing source one could potentially use a between event variance that is smaller than 2 in seismic hazard calculations thus these results may help to resolve the inconsistencies that are now present between the national hazard maps and some precariously balanced rocks in southern california 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif 3 embed inline graphic 3 gif

upper rhine graben role of preexisting structures during rift evolution 1 the evolution of the cenozoic upper rhine graben was controlled by a repeatedly changing stress field and the reactivation of a complex set of crustal discontinuities that had come into evidence during permo carboniferous times a comparison of the spatial and temporal thickness distribution of synrift deposits with preexisting fault patterns permits to infer a sequence of distinct basin subsidence phases that can be related to changes in the ambient stress field reactivation of a system of late palaeozoic fault systems outlining troughs and highs controlled the nucleation of initially separated middle and late eocene basins the depocenters of which coincided with a preexisting wsw ene trend during oligocene crustal extension the individual basins coalesced resulting in the development of the ssw nne striking upper rhine graben during the late oligocene chattian change in stress field the upper rhine graben was probably reactivated as a dextral strike slip system with the central graben segment forming a releasing bend during the early miocene aquitanian a major reorientation of the regional stress field is held responsible for the main subsidence phase of the northern parts of the upper rhine graben this is reflected by a counterclockwise rotation and northeastward shift of the depocenter axis and later by the middle miocene uplift and erosion of the southern parts of the upper rhine graben during the plio quaternary the upper rhine graben was reactivated as a sinistral strike slip system with the central graben segment forming a restraining bend

middle devonian lycopsids from high southern palaeolatitudes of gondwana argentina fossil plants are described from the upper part of the devonian lolen formation sierra de la ventana buenos aires province argentina in the area of estancia las acacias the sequence is composed mainly of dark grey shales and fossils were found in a single horizon where thin inter layered beds of fine reddish brown micaceous sandstones appear where the environment of marine deposition became more shallow the age of the lolen formation is presently established on the basis of brachiopods these being characteristic elements of the malvinokaffric realm from the gondwana lower devonian emsian the fossil plants are remarkably preserved given that they are in rocks that have undergone intense deformation the plants are identified as haplostigma sp and haskinsia cf h colophylla and suggest a middle devonian age givetian for the fossil bearing levels haskinsia identified on the basis of leaf morphology is the first well delimited middle devonian lycopsid genus described from argentina and the record from the most southerly palaeolatitude during the middle devonian haskinsia was distributed in tropical warm temperate and high southern latitude cool temperate zones

repeatable site and path effects on the ground motion sigma based on empirical data from southern california and simulated waveforms from the cybershake platform in this study we use two sets of residuals of the response spectral values to identify the repeatable effects due to specific ray paths and sites that are generally included in the standard deviation of the ground motion prediction equations gmpes one empirical set of residuals from the abrahamson et al 2014 gmpe and one set derived from simulated waveforms of the cybershake platform comparisons of the residuals at an oscillator period of 3 s lower usable limit of the 3d cybershake simulations show similarities between the site effects estimated from the two datasets with a correlation coefficient of 0 63 but the path effects are not similar correlation coefficient 0 for more than half of the sites evaluated comparing the cybershake path effects for moderate m w 6 5 and large m w 8 earthquakes showed that in most cases path effects from large magnitude earthquakes can be approximated using path effects from smaller earthquakes that have the same closest point to a site attention should be used when very large magnitude m w 8 events are involved and the fault crosses the sites finally the method for performing a fully nonergodic site specific probabilistic seismic hazard analysis including source path and site terms is outlined

arborescent lignophytes in the tournaisian vegetation of queensland australia palaeoecological and palaeogeographical significance abstract a middle tournaisian flora comprising several taxa of arborescent lignophytes is documented for the first time in australia it challenges earlier hypotheses considering that the early mississippian vegetation of australia was impoverished and dominated by small to medium sized arborescent lycopsids until the serpukhovian when climatic conditions became favorable to the thriving of the famous lignophyte dominated rhacopteris flora recorded in australia but also south america the present account is based on anatomically preserved fragments of trunks and branches from two localities of queensland in the broken river province and the burdekin basin three taxa are recognized dameria hueberi gen et sp nov the putative progymnosperm species protopitys buchiana goeppert 1850 and a taxon of uncertain affinities characterized by a pitus type of wood but which differs from the latter genus by anatomical traits relative to its primary body the possible occurrence of subtle growth rings in some of the woods from the burdekin basin and the conifer like traits of the dameria wood are interpreted as ecological clues suggesting that these trees may have inhabited drier settings than the wetland habitats generally inferred for the lycopsids this difference in habitats is suggested to explain the rarity of arborescent lignophytes compared to lycopsids in the australian record of plants of early mississippian age the three taxa reported in this paper represent the earliest record of arborescent lignophytes in australia after the global events that affected the vegetation at the devonian carboniferous boundary and the extinction of archaeopteris they show that the successional pattern of arborescent lignophytes around the devonian carboniferous boundary is comparable to that observed in western europe with the evidence of a diversification occurring as early as the middle tournaisian the palaeogeographic and stratigraphic distribution of protopitys and dameria indicates the occurrence of extensive floral exchanges between southern laurussia and north eastern gondwana in the late devonian to mississippian

devonian plants from colombia with discussion of their geological and palaeogeographical context plant fossils are described from the cuche formation eastern cordillera colombia in the area of floresta those identified as colpodexylon cf deatsii banks and cf archaeopteris sp suggest an earliest late devonian frasnian age for the formation these or similar taxa are also found in contemporaneous deposits in western venezuela and other elements of the venezuelan flora are found in a geographically intermediate locality all three devonian plant localities in the northwest of south america are within the colombian eastern cordillera and its northern extension the venezuelan perija range an area that has been integrated as a part of the so called eastern andean terrane or central andean province supposedly accreted to the autochthonous block of the guyana shield during the early jurassic or before although both invertebrates and plants from this terrane have strong affinities to north american and european assemblages and might be interpreted as implying a laurussian origin for the eastern andean terrane the evidence is not yet unequivocal with some authors postulating an in situ development of this province