the eastern termination of the zagros fold and thrust belt iran structures evolution and relationships between salt plugs folding and faulting 1 the zagros mountains result from the ongoing collision between the arabian and central iran plates the main features of the eastern zagros are 1 numerous emerged or buried salt diapirs made up of late precambrian hormuz salt and 2 the irregular along strike shape of the collision related detachment folds with frequent bending to understand this layout four geological cross sections have been constructed from the persian gulf foreland basin to the inner part of the zagros fold and thrust belt shortening in the deformed parts of the sections is less than 10 and is mainly accommodated by detachment folding we show that late cenozoic folding occurred in a region that was already punctuated by salt domes and diapirs in fact almost continuous halokinesis developed since the earlier paleozoic i e just short time after the deposition of the hormuz salt and continued up to the present these preexisting salt structures and their relevant local thickening strongly influenced both the localization and the direction of folds

structural evolution of the laurentian margin revisited southern quebec appalachians implications for the salinian orogeny and successor basins the laurentian margin of the appalachians is divided into external and internal zones on the basis of metamorphic and structural contrasts in the southern quebec internal zone silurian to early devonian southeast verging structures are superimposed on northwest verging structures whereas most of the external zone lacks such overprints regional backthrust faults define a major upper plate lower plate boundary the external zone rocks are in the hanging wall and internal zone rocks are in the footwall metamorphic rocks with silurian early devonian 40 ar 39 ar ages 430 410 ma characterize the lower plate to the east the saint joseph fault and the baie verte brompton line are southeastdipping normal faults that crosscut the upper plate lower plate boundary metamorphic rocks with middle ordovician 40 ar 39 ar ages 469 461 ma and rocks of the external zone both occur in the downthrown side of the saint joseph fault and the baie verte brompton line u pb and 40 ar 39 ar ages suggest that the northwest verging structures are related to ophiolite obduction and crustal thickening during the taconian orogeny ca 480 445 ma whereas the southeast verging structures formed during silurian early devonian backthrusting and normal faulting the revised structural interpretation has implications for the salinian orogeny and involves 1 southeast directed transport of the taconian crustal wedge of the upper plate followed by normal faulting and juxtaposition with the lower plate along the saint joseph fault and the baie verte brompton line and 2 the forma

geochemistry mineralogy and technological properties of the main stephanian carboniferous coal seams from the puertollano basin spain this study is focused on the occurrence and distribution of mineral matter and major and trace elements in the high volatile bituminous coal from puertollano south central spain the relationship between ash behaviour and inorganic composition as well as the possible formation of fouling and slagging deposits in boilers during the conversion process were investigated the puertollano coals do not exhibit plastic properties despite their rank probably because of their high ash and inertinite contents the puertollano coal has medium to low total s content 0 48 to 1 63 db with a mean of 1 0 db and is characterised by relatively high contents of si pb sb and cs some elements such as as cd co cr cu ge li mn ni w and zn are also present in relatively high contents the enrichment in a number of heavy metals could be attributed to the common sulphide ores occurring near the puertollano coal deposit the following trace elements affinities are deduced a sulphide affinity as co cd cu ni sb tl and zn b aluminum silicate affinity k ti b co cr cs cu ga hf li nb rb sn ta th v zr and lree c carbonate affinity ca mg mn and b d organic affinity b the very high si levels and the anomalous enrichment in cs ge pb sb and zn shown by the puertollano coals account for the high contents of these elements in the puertollano fly ash when compared with the other spanish coal fly ashes the chemical composition of the high temperature ash hta is consistent with the trend shown by the ash fusion temperatures aft and also with the predictive indices related to slagging and fouling propensities thus the ash fusion temperatures increase with high values of al2o3 as well as with the decrease in fe2o3 cao and mgo

coal facies studies in spain this work is a synthesis of the distribution of the main coal basins and sub basins in spain as well as the research carried out on their coal facies the coal fields are distributed through the paleozoic mainly pennsylvanian mesozoic cretaceous and cenozoic times peats also exist in the southeast spain granada area although these types of deposits are not included in this review spanish coal basins are both of a paralic and intramontane type and the coal rank is highly variable from lignite in the case of the younger coal seams to anthracite for those of carboniferous age

quartz arenites of the cambro ordovician kamouraska formation quebec appalachians canada ii eolian sands in deep sea sedimentary gravity flow deposits the kamouraska formation is a quartz arenitic unit of latest cambrian earliest ordovician age in the quebec appalachians that was deposited by hyperconcentrated to concentrated density flows in a meandering submarine canyon on the continental slope bordering the iapetus ocean as outlined in a companion paper detailed petrographic study of the quartz arenites of the kamouraska formation combined with scanning electron microscopy of grain surface textures suggests that the quartz sands are of eolian origin having been derived from an inland desert or less likely a barrier beach dune system transport of the mature quartz arenitic sand onto the shelf and deposition into the deep sea was not accompanied by substantial mixing with material from other sources thus preserving the inherited eolian characteristics a modern analogue for the eolian interpretation of the deep sea quartz arenite beds is as follows thick late pleistocene eolian sand beds on a modern abyssal plain in the east atlantic referred

lithospheric scale folding numerical modelling and application to the himalayan syntaxes we describe the eastern and western himalayan syntaxes which are large scale antiforms situated at geodynamically similar locations and the metamorphic evolution of which is coeval in the india asia collisional history to understand the mechanical plausibility of the structural interpretation we present two dimensional finite element modelling of lithospheric folding the models reveal the coeval development of adjacent synformal basins analogous to the peshawar and kashmir basins on both sides of the western syntaxis similarities between geological data and calculated models indicate that lithospheric buckling is a basic response to large scale continental shortening and an efficient mountain building process

stratigraphie framework for the cambrian ordovician rift and passive margin successions from southern quebec to western newfoundland the taconian humber zone stretches from western newfoundland to southern quebec the early cambrian slope succession in newfoundland is found in the curling group whereas in quebec various units were deposited during that first time slice biostratigraphic data allow correlation of the curling group with the labrador group in newfoundland and with the newly time constrained slope succession in quebec the end of the rift drift transition is marked by a sea level lowstand at the end of the early cambrian the middle cambrian to latest early ordovician passive margin history recorded five cyclic sea level fluctuations three of these cycles are recorded in the shallow marine middle to late cambrian platform port au port group and slope sediments preserved in the cow head and northern head groups in newfoundland the biostratigraphic information assists correlation with cambrian passive margin units in quebec major sea level lowstands are recognized along the continental margin in early middle late camb

experiments on simultaneous faulting and folding above a basement wrench fault abstract wrench zones commonly show en echelon patterns of folds in the stratified cover above a basement fault examples are the darien basin in panama and the inglewood fault trend in california folds are often associated with synthetic and antithetic wrench faults but the time relationships between folds and faults may not be obvious we have done experiments where simultaneous faulting and folding occur above a basement fault four experiments were performed using a simple apparatus capable of imposing localised strike slip motions this apparatus consists of two plastic plates one can be moved laterally past the other by a piston thus modelling lateral motion on a single basement fault models were properly scaled to account for gravitational forces brittle behaviour of sandstone and ductile behaviour of clay or shales in the upper crust each model is a vertical succession of silicone layers and sand layers each layer is 2 mm thick except for the basal silicone layer which is 2 4 6 or 8 mm thick in experiments 1 2 3 or 4 respectively all models were deformed at the same slip rate on the basal fault 1 cm h 1 experiments 1 2 and 3 with 8 cm total horizontal sinistral offset were designed to investigate the influence of basal silicone layer thickness on the deformation of a multilayered model experiment 4 with 20 cm of total offset was designed to investigate the influence of an increasing left lateral offset on folding and faulting with a 2 mm thick basal silicone layer experiment 1 synthetic strike slip faults appeared en echelon above the basement fault no folds were visible at the surface of the experiment but the interfaces between sand and silicone layers showed millimetric folds en echelon above the basement fault with a 4 mm thick basal silicone layer experiment 2 en echelon synthetic strike slip faults and folds appeared above the basement fault faults and folds rotated progressively anticlockwise and synclines were activated as dextral antithetic shear zones with a 6 mm thick basal silicone layer experiment 3 synthetic faults and en echelon folds appeared as before but the fold amplitude was larger than in experiment 2 an increasing left lateral offset produced anticlockwise rotation of faults and folds as before and synclines were activated as dextral antithetic shear zones in experiment 4 after 16 cm of left lateral offset the anticlockwise rotation of the folds was such that antithetic dextral shear zones became almost parallel to the basement fault and were then reactivated as synthetic sinistral shear zones

palynological evidence for late westphalian early stephanian vegetation change in the dobrudzha coalfield ne bulgaria the dobrudzha coalfield in northeast bulgaria has coal bearing deposits ranging from latest namurian to early stephanian age late bashkirian to moscovian age palynology of the coals in the upper makedonka krupen and gurkovo formations has been used to identify major changes in the vegetation during late westphalian and early stephanian times the palynomorphs were grouped in two different ways according to general morphotype and according to parent plant group and stratigraphical trends in the two sets of groups used to identify vegetation change through the succession detrended correspondence analysis was also used to identify ecological relationships between the palynofloras in the upper makedonka and krupen formations lycophyte spores mostly comprise 15 25 of the palynofloras in the thicker seams but in the thinner coals they can represent up to 55 of the other plant groups ferns are the most abundant representing 31 69 in the thicker seams 12 41 in the thinner seams this suggests that the arborescent lycophytes were mainly restricted to pioneer vegetation in these upland areas and were replaced by ferns as the peat substrates became better developed suggesting better drained conditions the thinner seams also have a noticeable component of sphenophyll spores indicating significant areas of open conditions allowing colonization by these scrambling plants in the gurkovo formation coals lycophytes form an even smaller part of the palynological spectra usually less than 10 and in only one sample just over 25 fern spores make up 43 57 of the palynofloras this is in contrast to the palynofloras reported from contemporaneous clastic deposits in south wales most of which consist mostly of 34 60 lycophyte spores and 14 34 fern spores even more marked is the difference from the contemporaneous coals formed in lowland settings in the usa which have mostly 50 lycophyte spores this evidence suggests that the timing of the decline in abundance of arborescent lycophytes varied according to elevation above sea level in lowland coastal settings the lycophytes remained dominant until middle late cantabrian times but in more inland areas they were progressively replaced mainly by arborescent ferns during late westphalian times

a depositional model for the taylor coal bed martin and johnson counties eastern kentucky abstract this study investigated the taylor coal bed in johnson and martin counties eastern kentucky using field and petrographic techniques to develop a depositional model of the coal bed petrography and chemistry of the coal bed were examined multiple benches of the taylor coal bed were correlated over a 10 km distance three sites were studied in detail the coal at the western and eastern sites were relatively thin and split by thick clastic partings the coal at the central site was the thickest and unsplit two major clastic partings are included in the coal bed each represents a separate and distinct fluvial splay the taylor is interpreted to have developed on a coastal plain with periodic flooding from nearby structurally controlled fluvial systems doming is unlikely due to the petrographic and chemical trends which are inconsistent with modern indonesian models the depositional history and structural and stratigraphic setting suggest contemporaneous structural influence on thickness and quality of the taylor coal bed in this area

the st lawrence platform and appalachian deformation front in the st lawrence estuary and adjacent areas quebec canada structural complexity revealed by magnetic and seismic imaging new magnetic and seismic datasets offer a unique opportunity to document the geometry of the appalachian front in a poorly studied segment of the orogen interpretation of high resolution magnetic data allows for the first time the documentation of the contact between the autochthonous st lawrence platform and the appalachians and highlights the regional significance of previously poorly documented ene faults that experienced post ordovician strike slip motion seismic data reveal tectonic slices in the foreland domain underlying the appalachians and show that the depth of the decollement at the base of the appalachian tectonic wedge varies significantly taken together geological magnetic and seismic data suggest that the geometry of the appalachian front exhibits significant variations in map and cross section views and recorded a polyphased structural history

permian vegetational pompeii from inner mongolia and its implications for landscape paleoecology and paleobiogeography of cathaysia plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time here we report such a flora from an early permian ca 298 ma ash fall tuff in inner mongolia a time interval and area where such information is filling a large gap of knowledge about 1 000 m2 of forest growing on peat could be reconstructed based on the actual location of individual plants tree ferns formed a lower canopy and either cordaites a coniferophyte or sigillaria a lycopsid were present as taller trees noeggerathiales an enigmatic and extinct spore bearing plant group of small trees is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community landscape heterogenity is apparent including one site where noeggerathiales are dominant this peat forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval this permian flora demonstrates both similarities and differences to floras of the same age in europe and north america and confirms the distinct character of the cathaysian floral realm therefore this flora will serve as a baseline for the study of other fossil floras in east asia and the early permian globally that will be needed for a better understanding of paleoclimate evolution through time

peat forming environments of westphalian a coal seams from the lower silesian coal basin of sw poland based on petrographic and palynologic data abstract the petrographic and palynologic compositions of coal seams of the acler formation upper carboniferous westphalian a from northwestern and southeastern part of the lower silesian coal basin lscb were examined coals studied are highly volatile bituminous coal where r o ranges from 0 91 to 1 09 seam 430 from the northwestern part of the basin contains high vitrinite percentage with rather low inertinite and liptinite contents while percentage of mineral matter is variable this petrographic composition is associated either with a predominance of lycospora in miospore assemblage or with a miospore assemblage of mixed character the abundance of lycospora reflects vegetation composed of the arborescent lycopsids while the mixed miospore assemblage is connected with diverse palaeoplant communities namely arborescent lycopsids calamites and ferns seams 409 and 412 413 from the southeastern part of the lscb are rich in inertinite and liptinite while the vitrinite content is moderate their characteristic feature is the occurrence of a diagnostic crassisporinite densosporinite amount of the mineral components in these coals is very low densosporites and related crassicingulate genera are main components of these miospore assemblages and were produced by herbaceous and or sub arborescent lycopsids these petrographic and palynologic features were the basis for distinguishing three maceral miospore associations an arborescent lycopsid and mixed associations occurring in the seam 430 and a herbaceous and or sub arborescent lycopsid association which was recorded in seams 409 and 412 413 the first two assemblages are interpreted as having been deposited in a planar rheotrophic mire whereas the herbaceous and or sub arborescent lycopsid association is thought to have developed in an ombrotrophic domed mire

qinling gneiss domes and implications for tectonic evolution of the early paleozoic orogen in central china abstract the qinling arc terrane qat at the southern margin of the north qinling early paleozoic orogen central china is composed of gneiss domes overridden by cold allochthon nappes the gneiss domes are characterized by migmatitic and plutonic cores of granite or gabbro and overlying upper amphibolite to granulite facies metamorphic sequences with pervasive injection of leucogranitic veins the gneiss domes display a high temperature domal foliation dipping radially away the core and a down dipping stretching lineation cascading folds occur in the mantling metamorphic rocks the new data of zircon monazite u pb dating suggest that the gabbroic and granitic plutons formed at 514 476 ma and 495 441 ma respectively whereas the high grade metamorphism of the mantling rocks took place at 469 412 ma and the leucogranitic veins formed at two main episodes 472 440 ma and 416 413 ma mica 40ar 39ar dating yields 402 328 ma for the cooling ages of the leucogranitic veins and gneissic rocks the basaltic magma underplated into the qat lower crust resulted in partial melting producing granitic magma at the late cambrian to middle ordovician during northward subduction of the shangdan proto tethyan oceanic slab buoyant upwelling of the migmatitic and plutonic core was promoted by constriction in the lower crust and decompression extension in the upper crust during the silurian since the closure of the shangdan ocean and the collision between the north china block and south china block 400 ma the qinling gneiss domes experienced rapid uplift and were finally overthrust by the upper allochthon transported from the north qinling

the last interglacial glacial period on spitsbergen svalbard the glaciation history of svalbard 78 n and the nw barents sea is reconstructed for the last 130 ka based on studies of sediments exposed in coastal cliffs at the head of isfjorden four different till beds separated by marine sediments are recognized the lowest marine formation containing mytilus edulis reflects warmer conditions than at present and is correlated with the last interglacial the eemian of europe and oxygen isotope substage 5e in the deep sea the post eemian tills are inferred to represent major glaciations around 110 ka bp 75 50 ka bp and 25 10 ka bp during the intervening intervals the glaciers on svalbard were not significantly larger than at present and the nw barents sea was probably ice free the ice free periods named phantomodden and kapp ekholm interstadials lasted from about 110 to 75 and from 50 to 25 ka bp respectively the marine fauna from both these interstadials indicate seasonally ice free conditions the ages of the recorded glaciations coincide with or are slightly younger than periods with insolation minima which at this latitude is determined by a low tilt of the earth s axis thus we postulate that the quaternary glaciations of svalbard were driven by orbital variations with the 41 ka tilt period in contrast to the lower latitude glaciations of scandinavia that were partly driven by the precession cycle with a periodicity of around 23 ka

comparison of the petrography palynology and paleobotany of the stockton coal bed west virginia and implications for paleoenvironmental interpretations abstract the stockton coal bed middle pennsylvanian is a relatively high ash coal composed primarily of moderately thin banded sparsely thin banded and nonbanded coal splint and cannel coal comparisons of petrographic palynologic and paleobotanic data gathered from the same sample sets from a single column of the stockton coal bed indicate that compositional correspondences among the sets exist regardless of coal type some correspondences are believed to exist because of original plant constituents and others because of the paleoenvironment of peat formation using some combination of these data is critical when interpreting paleoenvironmental conditions because 1 a direct correspondence is lacking between many of the data and 2 each of the three data sets provides a unique and important perspective on the paleomire the stockton paleomire in the area of this study supported a diverse flora that consisted of both small and arboreous lycopsids small ferns and tree ferns calamites cordaites and pteridosperms there appear to have been two successions of lycospora spore dominated vitrinite rich liptinite poor peat formation which were followed by inertinite rich peat formation marked by a tree fern dominant spore assemblage and abundant unidentifiable plant tissues these are interpreted to be two water laden or topogenous peat formational stages followed by slightly domed better drained peat formation

paleoecological interpretation of a middle pennsylvanian coal bed in the central appalachian basin u s a abstract at least 180 small spore species assignable to 62 miospore genera have been identified from the middle pennsylvanian hernshaw coal bed in southern west virginia and its stratigraphic equivalent the fire clay coal bed in eastern kentucky the established natural affinities of a majority of these miospore taxa indicate that the hernshaw fire clay peat swamp supported a diverse flora consisting of arborescent and herbaceous lycopods ferns tree like and small varities calamities and cordaites four floral groupings are recognized in the hernshaw fire clay coal bed the inferred paleoecology and vertical stratification of each of these four floral groupings is similar in structure to the phasic floral communities found in modern domed peat systems suggesting that the ancient hernshaw fire clay peat swamp was a domed deposit compositional characteristics petrographic make up ash yield and sulfur content associated with the four groupings are consistent with and support this interpretation where uninterrupted by inorganic partings the hernshaw fire clay coal bed commonly contains basal coal layers dominated by lycospora bearing arborescent lycopods with successive increments showing a progression to a more fern and herbaceous lycopod dominant flora in younger layers these observations are corroborated by petrographic analyses which show the bed to be compositionally stratified increments dominated by lycospora have high vitrinite contents in contrast to increments containing increased percentages of fern and herbaceous lycopod affiliated taxa that are enriched in inertinite macerals the volcanic ash fall preserved as the flint clay parting in the hernshaw fire clay coal bed had a considerable effect on the development of the ancient hernshaw fire clay peat swamp besides interrupting peat formation the presence of an inorganic substrate represent a major change in edaphic conditions within the swamp this disruption is demonstrated by a change in palynflora and by the establishment and proliferation of some plant groups notably cordaites and calamites that may have been better adapted to growth on mineral soils these palynologic and petrographic relationships thought to be indicative of a domed peat swamp origin are not confined to the hernshaw fire clay coal bed but appear to be characteristic of many coal beds in the appalachian basin and also of coal beds in other basins

interfering folds in constrictional deformation abstract experiments on buckle folding indicate that in pure constriction 2 3 2 3 there is an association of domes and basins with nonplane noncylindrical folds the areas of domes and basins are reduced with increasing deformation there is a dominant fold trend perpendicular to 3 with a less dominant trend perpendicular to 3 folds at an angle to these two sets may also occur the divergent folds link up in smooth arcs or join up at a dome or a basin over a relatively large domain the interference pattern produced by general constriction can be recognized by the association of domes and basins with nonplane noncylindrical folds by occurrence of hair pin bends of hinge lines of open folds by occurrence of amoeboid outcrop patterns and by absence of a consistent overprinting relation among different sets of folds layers subparallel to the 3 axis of general constriction may give rise to two or more sets of coaxial cylindrical folds with orthogonal axial surfaces

formation of dome and basin structures results from scaled experiments using non linear rock analogues abstract dome and basin folds are structures with circular or slightly elongate outcrop patterns which can form during single and polyphase deformation in various tectonic settings we used power law viscous rock analogues to simulate single phase dome and basin folding of rocks undergoing dislocation creep the viscosity ratio between a single competent layer and incompetent matrix was 5 and the stress exponent of both materials was 7 the samples underwent layer parallel shortening under bulk pure constriction increasing initial layer thickness resulted in a decrease in the number of domes and basins and an increase in amplitude a arc length l wavelength and layer thickness hf samples deformed incrementally show progressive development of domes and basins until a strain of ey z 30 is attained during the dome and basin formation the layer thickened permanently while a l and increased a dominant wavelength was not attained the normalized amplitude a increased almost linearly reaching a maximum of 0 12 at ey z 30 during the last increment of shortening ey z 30 to 40 the domes and basins did not further grow but were overprinted by a second generation of non cylindrical folds most of the geometrical parameters of the previously formed domes and basins behaved stable or decreased during this phase the normalized arc length l hf of domes and basins is significantly higher than that of 2d cylindrical folds for this reason the normalized arc length can probably be used to identify domes and basins in the field even if these structures are not fully exposed in 3d

relationship between joint spacing and bed thickness in sedimentary rocks effects of interbed slip this paper consists of three parts the first part presents a critical review of previous mechanical models on the relationship between joint spacing s and bed thickness t in sedimentary rocks the second part describes a new mechanical model dealing with the effects of interbed slip on joint spacing the third part presents the comparison between theoretical results of the model and joint data measured from cambrian flysch sediments at plage victor in the saint jean port joli area of the quebec appalachians this study demonstrates two formation mechanisms of tensile joints near end fracturing takes place in the layers with smaller tensile fracture strength c 0 30 mpa and smaller interbed shear strength 0 20 mpa while mid point fracturing occurs in those layers with larger c 0 50 mpa and 0 30 mpa values for the rocks with moderate tensile fracture strength 30 c 0 50 mpa and interbed shear strength 20 0 30 mpa the near end fracturing and mid point fracturing take place preferentially in the thicker and thinner brittle layers respectively in the regime of near end fracturing the correlation between s and t is linear and independent of the thickness of the bounding non jointing layers d in the regime of mid point fracturing however the s t relationship can be either linear or non linear depending on the variation of d value the present study also suggests that the near end fracturing is probably the prevailing process for the formation of tensile joints in bedded sedimentary rocks and that the coefficient of joint spacing k defined by the ratio of s to t is considered as an indicator of c 0 2 0 for the jointed layer

hinge migration as a mechanism of superimposed folding abstract paraffin wax analogue modelling of superimposed folding shows how early fold shape and orientation determine fold axis orientation type of interference pattern and mechanism of superposed folding during two successive deformations the behaviour depends on the angle between the first and second compression directions i when they are perpendicular to each other classic superposed folding with either domes and basins or folds with vertical axes develop depending on whether the earlier folds were open or closed ii when the two compression directions are oblique the earlier folds rotate the degree of rotation depends on the angle between the first folds and the later compression direction and is proportional to the amount of strain the orientations of the new folds are close to those of the earlier open folds the final deformation pattern consists of domains where the orientations of the axes depend on whether the early folds were previously either open or closed many early folds are reused to become later folds by the mechanism of hinge migration these results are consistent with the pattern of superimposed folding observed in the devoluy structure of the french alps they show that simply by studying the directions of fold axes in areas of superposed folding it is not possible to define compression directions moreover there is the possibility that superposed folding may go unnoticed if hinge migration has occurred

changing patterns of pennsylvanian coal swamp vegetation and implications of climatic control on coal occurrence abstract improved regional and interregional stratigraphic correlations of pennsylvanian strata permit comparisons of vegetational changes in euramerican coal swamps the coal swamp vegetation is known directly from in situ coal ball peat deposits from more than 65 coals in the united states and europe interpretations of coal swamp floras on the basis of coal ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps changes in composition of pennsylvanian coal swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate paleobotany and paleogeography of the euramerican province indicate a moist tropical paleoclimate rainfall runoff and evapotranspiration were the variable climatic controls in the distribution of coal swamp vegetation peat accumulation and coal resources in relative terms of climatic wetness the pennsylvanian period is divisible into five intervals which include two relatively drier intervals that developed during the lower middle and middle upper pennsylvanian transitions the climate during early pennsylvanian time was moderately wet and the median in moisture availability early middle pennsylvanian was drier probably seasonally dry wet late middle pennsylvanian was the wettest in the midcontinent early late pennsylvanian was the driest and late late pennsylvanian was probably the wettest in the dunkard basin the five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation regional differences in basinal geology and climate were significant variables but the synchronous control of paleoclimate was of primary importance

permian coal forest offers a glimpse of late paleozoic ecology little evokes a sense of wonder about the past like moments frozen in time the contorted bodies of pompeii s horrified citizens fixed in their final poses the footprints of an ancient hominin family cemented on an african savanna the tracks of a jurassic predator closing in on unsuspecting prey along a muddy riverbank or tree stumps from an ancient carboniferous rainforest buried in place by a sudden deluge fig 1 these instances provide us with poignant snapshots of deep time and just like a photograph they also may capture some of its dynamism in pnas the work by wang et al 1 reconstructs the vegetation of an 300 million year old early permian aged mire that was buried and killed by a volcanic ashfall one of a rare but increasing number of occurrences that geologists term t0 deposits 2 the study represents a high resolution view of a permian aged coal forest so called because it accumulated atop peat now coal an extinct ecosystem that persisted in tropical east asia long after its better known pennsylvanian aged counterparts had all but dried up in europe and north america 1 by using a quantitative analysis of plant fossils preserved in tuff above the coal seam the work by wang et al 1 provides a 3d reconstruction of the mire vegetation before the eruption from which patterns of heterogeneity and ecological gradients emerge such t0 deposits allow paleoecologists to examine the past in much the same way neoecologists appraise modern environments and to ask questions about the conformity of observed patterns with various aspects of ecological theory

superposed buckle folding in the eastern iberian chain spain abstract the aliaga area eastern iberian chain shows large scale examples of buckle superposition developed during tertiary folding in most cases ene trending folds overprint earlier nnw sse trending ones the resulting structures are mapped analysed and genetically classified by comparison with analogue models described by several authors the following types are found standard type 1 1a dome and basin structure 1b unequal wavelength overprinted folds modified type 1 1c t shaped joined folds 1d t shaped abutting folds 1e l shaped folds 1f snake like folds standard type 2 2a non cylindrical buckling of earlier axial surfaces involving hinge replacement different superposed sets of flexural slip striations record successive folding episodes in snake like folds and hinge replacement in the case of type 2a superpositions types 1 and 2 apparently develop where the earlier folds have interlimb angles over and below 90 respectively which fits the results of analogue modelling and theoretical analysis by previous authors types 1b and 1d are associated with higher w1 w2 wavelength ratios than types 1a and 1c other controlling factors are viscosity contrast and erosion processes specifically erosion of competent limestone beds in the hinge zone of a nnw sse trending anticline allowed the near vertical eastern limb to be refolded into snake like folds

aliphatic and aromatic biomarkers from carboniferous coal deposits at dunbar east lothian scotland palaeobotanical and palaeoenvironmental significance carboniferous visean coals from dunbar east lothian scotland contain well preserved miospore and megaspore assemblages suggesting a lycopod dominated forest ecosystem with some ferns sphenopsids and pteridosperms the low rank of the coals and the well defined microflora permit assessment of the palaeoenvironmental significance of lipid biomarkers during the early carboniferous rock eval petrographic and lipid analyses indicate a fully terrestrial depositional environment although we also present and discuss a wide diversity of other lipid biomarkers alkanes hopanoids steroids we focus on the terrestrial derived biomarkers combustion derived pahs pyrene fluoranthene benzo a anthracene chrysene and triphenylene indicate the occurrence of forest fires in the study areas during early carboniferous times alkyldibenzofurans are considered to derive from lichen biomass retene cadalene simonellite tetrahydroretene and kaurane are poorly specific and can derive from a variety of early palaeozoic land plants abietane phyllocladane ent beyerane and 4 h eudesmane as well as bisnorsimonellite diaromatic totarane diaromatic sempervirane and 2 methylretene however as yet had only been reported from conifers which do not appear in the fossil record until the late carboniferous within the lower carboniferous forest ecosystem arborescent lycopsids and pteridosperms are proposed as alternative sources for these compounds

paleobotanical and paleoecological constraints on models of peat formation in the late carboniferous of euramerica abstract the dominant plants of the late carboniferous lowland tropics were taxonomically and structurally distinct from those of any later time periods dominance was distributed among lycopsids ferns sphenopsids pteridosperms and cordaites and each of these groups had distinctive and different ecological preferences and amplitudes peat forming habitats were dominated by lycopsids throughout the westphalian with a significant cordaitean element in the middle westphalian during the stephanian tree ferns were dominant following major extinctions near the westphalian stephanian transition each of the major plant groups had distinctive architectures and tissue composition trees contributed up to 95 of the peat biomass and tree forms of lycopsids psaronius and medullosa lack good modern analogues the cordaites were the only woody plant group to contribute significantly to peat and then only during the mid westphalian structurally wood like lycopsid bark is the major woody tissue encountered in most westphalian coals tree ferns and pteridosperms were largely parenchymatous in construction the stigmarian root systems of lycopsids also were largely parenchymatous the tissue structure of these dominant plant suggests the need for extreme caution in the inference of mire ecological conditions or vegetational structure from coal petrographic data peat formed under arborescent ferns or pteridosperms or peat repeatedly exposed to decay and rerooting by stigmarian root systems of lycopsids would have a distinctly non woody signature and yet would have formed in a forested environment a summary is presented of the autecology and synecology of mire plants emphazing the structural framework provided by lycopsids during the westphalian certain constraints in the links between peat biomass and miospore palynology are discussed in terms of over representation under representation and non representation the formulation of smith s four phase hydroseral model is discussed and compared with more recent data available from plant paleoecology the current debate over an ombrotrophic vs rheotrophic origin of late carboniferous peats relies in large part on paleobotanical data almost entirely palynological in combination with petrographic analyses ecological studies of miospores and of coal ball and compression macrofossils and the linkage of miospores to source plants permit the re evaluation of mire successional models evidence for tree lycopsids sphenopsids pteridosperms and cordaites suggests growth mainly in rheotrophic mires tree ferns are likely candidates for growth in domed mires although evidence is ambiguous and some tree ferns clearly grew under rheotrophic conditions densospores produced by at least sporangiostrobus lycopsid subtrees have been considered diagnostic of ombrotrophic conditions abundant evidence refutes this simplistic interpretation and suggests broad ecological amplitudes for densospore producers including growth under rheotrophic conditions although plant fossils alone can not resolve most of the major debates in modern coal geology paleobotany does contribute significantly to our understanding of ancient mires an approach combining paleobotanical data with petrography sedimentology and geochemistry on a case by case basis is most likely to produce a clear picture

deposition of the cambrian continental rise the st roch formation near st jean port joli quebec detailed mapping between plage victor and st jean port joli has enabled us to add a 550 m section to the top of the existing 450 m section of hubert making the longest continuous section anywhere

paleoenvironmental conditions of puertollano coals spain petrological and geochemical study abstract in the present work petrographic geochemical and mineralogical data have been combined with results from prior paleobotanical studies in order to determine the sedimentary and postsedimentary diagenetic factors responsible for the physicochemical properties of coal seams and associated sediments from the puertollano stephanian coal basin although the coal seams 4 originated under similar lacustrine conditions the highest coal seams 1 and 1 bis show higher production preservation of structured tissues telinite and collotelinite than the lowest coal seams 2 and 3 where destruction of the cell tissues collodetrinite is predominant differences in degree of preservation as a result of changes in the environmental sedimentary conditions in the water table ph redox may explain the different maceral distribution this feature may also be due to the increase in degree of humification from the highest seams 1 and 1 bis to the lowest seams 2 and 3 however the gentle thermal maturation undergone by these stephanian coals only produced a slight modification in the physicochemical properties of the organic matter in general alkaline synsedimentary conditions could be deduced from the dominance of organic sulphur with respect to pyritic sulphur reducing conditions for seam 1 1 bis and 2 and more oxidant conditions for seam 3 can be deduced from maceral sulphur and carbonate distribution other diagenetic processes involved organic and inorganic sediments for example a kaolinitisation process with a different intensity for the early diagenetic stages suggests the occurrence of leaching processes which affected both organic and inorganic sediments

palaeoclimatic and site specific conditions in the early permian fossil forest of chemnitz sedimentological geochemical and palaeobotanical evidence abstract as significant indicators of deep time palaeoclimate a number of new palaeontological pedological and geochemical characteristics are provided for the chemnitz fossil lagerstatte to depict more precisely its environmental conditions for the first time several lines of evidence indicate that this fossil forest instantaneously preserved by volcanic deposits once received an annual precipitation of around 800 1100 mm but grew on a nearly unweathered palaeosol although the composition of this rich and diverse t0 assemblage suggests a hygrophilous dense and multi aged vegetation dominated by conservative lineages the habitat was affected by environmental disturbances and pronounced seasonality repeated changes in local moisture availability are suggested by geochemical proxies the co occurrence to intergrowth of calcic and ferric glaebules in the palaeosol and developmental traits of perennial vegetational elements specific substrate adaptation is reflected by different root systems and cyclic growth interruptions recorded in the stems branches and roots of long lived woody plants many differentially adapted terrestrial animals complete the more comprehensive reconstruction of a late sakmarian ecosystem and its climatic and preservational controls albeit spatially confined this diverse in situ record may contribute to understand wetland dryland dynamics of sub tropical northern hemisphere pangaea

a late stephanian forest swamp with sporangiostrobus fossilized by volcanic ash fall in the puertollano basin central spain abstract about 600 m of coal measures and oil shales in the puertollano basin of castilla la mancha contain late stephanian floras an ash fall now a tuff band intercalated in the lower part of coal seam iii fossilized a swamp forest floor with abundant mature sporangiostrobus remains that are associated with vegetative bodeodendron the same lycophyte the pecopterid fern scolecopteris and the sphenophytes asterophyllites and annularia sphenophylloides the floral composition of this tuff band was analyzed and the various stages of the disarticulation process of sporangiostrobus were determined the fertile apices of these lycophyte trees fell onto the forest floor where flattening occurred as the result of decay of the wide cortical area and the central part of the siphonostele subsequently the long distal laminae of sporophylls were removed and afterwards the sporangia leaving only the short stubby horizontal proximal parts of the sporophylls attached to the hulk of these fertile apices of stems or major branches disarticulation was the means of dissemination of the sporangia of this heterosporous lycophyte that produced cristatisporites densosporites cingulizonates microspores and zonalesporites megaspores sporangiostrobus was an extremely prolific producer of densospores and there is a direct correlation between sporangiostrobus and the high densospore count and durite content of seam iii the stratigraphic succession associated with seam iii is described environmental conditions are discussed in relation to the numerous well over a thousand specimens large almost complete remains of sporangiostrobus found in the lower tuff band the detached fertile apices were lying on the forest floor when the volcanic ash fall took place and were preserved in situ where they were shed from the bodeodendron tree this implies an absence of water currents although the general environment must have been humid in view of the overall lacustrine setting it is noted that this is one of the rare examples in europe and north america palaeoequatorial belt where lycophytes continued to be the dominant peat forming element in late stephanian time the systematic position of sporangiostrobus is briefly discussed this lycophyte belonged to a conservative group that was widely distributed throughout the world its important role in latest carboniferous peat forming environments has not been realized until now because of the rarity of richly preserved sporangiostrobus remains

information from folds a review abstract folds are spectacular geological structures that are seen in layered rock on many different scales to mark 30 years of the journal of structural geology we review the information that can be gained from studies of folds in theory experiment and nature we first review theoretical considerations and modeling from classical approaches to current developments the subject is dominated by single layer fold theory with the assumption of perfect layer parallel shortening but we also review multilayer fold theory and modeling and folding of layers that are oblique to principal stresses and strains this work demonstrates that viscosity ratio degree of non linearity of the flow law anisotropy and the thickness and spacing distribution of layers of different competence are all important in determining the nature and strength of the folding instability theory and modeling provide the basis for obtaining rheological information from natural folds through analysis of wavelength thickness ratios of single layer folds and fold shapes they also provide a basis for estimating the bulk strain from folded layers information about folding mechanisms can be obtained by analysis of cleavage and fabric patterns in folded rocks and the history of deformation can be revealed by understanding how asymmetry can develop in folds by how folds develop in shear zones and how folds develop in more complex three dimensional deformations

3d numerical modeling of forward folding and reverse unfolding of a viscous single layer implications for the formation of folds and fold patterns abstract the main aims of this study are to show i that non cylindrical three dimensional 3d fold shapes and patterns can form during a single unidirectional shortening event and ii that numerical reverse modeling of 3d folding is a feasible method to reconstruct the formation of 3d buckle folds 3d viscous newtonian single layer folding is numerically simulated with the finite element method to investigate the formation of fold shapes during one shortening event an initially flat layer rests on a matrix with smaller viscosity and is shortened in one direction parallel to the layering forward modeling with different initial geometrical perturbations on the flat layer and different lateral boundary conditions generates non cylindrical 3d fold shapes and patterns the simulations show that in reality the initial layer geometry and the boundary conditions strongly control the final fold geometry fold geometries produced from the forward folding models are used as initial setting in numerical reverse folding models with parameters identical to those of forward models these reverse models accurately reconstruct the initial geometry of forward models with also only one extension event parallel to the previous shortening direction the starting geometry of the forward models is inaccurately reconstructed by the reverse models if a significantly different viscosity ratio than in the forward models is used this work demonstrates that reverse modeling has a high potential for reconstructing the deformation history of folded regions and rheological constraints such as viscosity ratio reverse models may be applied to natural 3d fold shapes and patterns in order to determine if they formed i during a single or multiple deformation events and ii as active buckle folds with a viscosity ratio 1 or as passive kinematic folds without buckling this approach may find much application to fold interference patterns in particular

modes of superposed buckling in single layers controlled by initial tightness of early folds in a series of experiments with soft test models superposed buckling folds were produced in a competent layer resting on a slab of incompetent painter s putty the angle between the hinge lines of the first set of cylindrical folds f1 and the direction of the second compression p2 was varied in the different experiments the experiments showed that with an increase in the initial tightness of f1 there was a transition from one mode of superposed buckling to another when the interlimb angle of f1 was very large the superposed deformation gave rise to a dome and basin pattern the first mode of superposed buckling the second mode with small f2 folds riding over larger f1 folds developed when the initial interlimb angle ranged roughly between 135 and 90 the third mode was observed when the f1 interlimb angle was less than about 90 but the fold was not very tight in the third mode a set of non plane non cylindrical folds developed however the sinuous hinge line of the non cylindrical structure was newly created by replacing the old f1 hinge when f1 was very tight or isoclinal the fourth mode of superposed buckling led to the development of non plane non cylindrical folds without concomitant hinge replacement

stratigraphic and interregional changes in pennsylvanian coal swamp vegetation environmental inferences abstract quantitative analysis of pennsylvanian coal swamp vegetation provides a means of inferring organization and structure of communities distribution of these communities further provides inferences about environmental factors including paleoclimate our observations are based on in situ structurally preserved peat deposits in coal ball concretions from 32 coal seams in the eastern one half of the united states and from several seams in western europe and on spore assemblages from more than 150 seams there were three times of particularly significant and nearly synchronous vegetational changes in the midcontinent and appalachian coal regions during the pennsylvanian period each was different in kind and magnitude the first marked changes occurred during the early part of the middle pennsylvanian with the fluctuating decline in the high level of lycopod dominance the abundance of cordaites increased there was a rise in the occurrences of the lycopod herbs to form intercalated marshlands and an overall increase in floral diversity changes ensuing from this time also include shifts in dominant species of lycopod trees and a sustained rise in abundance and diversity of tree fern spores the next significant time of change was during the middle part of the middle pennsylvanian representing both a culmination of earlier trends and expansions of cordaites in the midcontinent where there was a maximum change in species without net loss of diversity tree ferns and medullosan pteridosperms attained subdominant levels of abundance and diverse lycopod species dominated except in the atokan desmoinesian transition of the midcontinent the third and sharpest break occurred near the middle late pennsylvanian boundary when extinctionsof the dominant coal swamp lycopods allowed development of tree fern dominance the late pennsylvanian coal swamps apparently were colonized or recolonized mainly by species from outside coal swamps rather than by the survivor populations of the middle pennsylvanian swamps paralleling the changes in floras through the pennsylvanian are changes in preservational aspects of the peat these include a decline in shoot root ratios from approximately 1 to

formation of dome in dome structures results from experimental studies and comparison with natural examples abstract dome in dome structures are frequent in salt provinces and in high grade rocks of orogens their origin is only poorly understood in the present study we have modelled dome in dome structures which result from constrictional radial in plane shortening of a competent layer embedded in a rising less competent matrix both the layer and the matrix consist of non linear viscous plasticine which display a viscosity contrast of 5 the deforming competent layer is characterized by 1 a striking downward drag along the margins 2 a sample scale first order dome and 3 numerous second order domes and basins straddling the first order dome with increasing layer thickness and strain the amplitude a arc length l and wavelength of the second order domes and basins increase however their growth rate is significantly smaller than that of non rising domes and basins which result from a bidirectional flow this restricted growth of rising domes and basins is attributed to the simultaneous growth of the first order dome and explains why hair pin type folds typical for non rising domes and basins are lacking even at higher finite strain similar dome in dome structures like those produced in the present study have been described from deeper levels of salt and gneiss domes or from foliation triple points of interfering diapirs

the influence of initial fold geometry on type 1 and type 2 interference patterns an experimental approach abstract experiments on superposed folding were performed in a plane strain pure shear rig using paraffin wax as an analogue for rocks a series of pre formed cylindrical folds were refolded with the compression direction acting parallel to the initial fold hinge direction the intermediate axis perpendicular to the first fold axial plane and the extension direction parallel to the first fold axial plane and perpendicular to its axis type 1 interference geometry roundness tightness and amplitude were varied to investigate the influence of first fold geometry on the interference patterns experimental folding of an initially planar layer oriented parallel to the first fold envelope provides a reference geometry for comparison the results suggest that hinge roundness has less influence on the interference pattern than other factors close initial folds refold into type 2 interference patterns which become even more pronounced as the tightness increases open folds produce type 1 interference patterns folds with the same interlimb angle and the same roundness produce different interference patterns depending on relative amplitude folds with relatively large amplitude are refolded into type 2 patterns whereas folds with small amplitude give clear dome and basin structures in a second set of experiments the compression direction also acted parallel to the first fold hinge but the orientations of the intermediate and extension axes were interchanged the interference patterns obtained are very similar to those in type 1 interference geometry suggesting that the major factor in determining whether type 1 or type 2 interference patterns develop is the initial fold geometry and not the kinematics of the second deformation

deformation progressive or multiphase abstract complexly deformed rocks that exhibit refolded folds and overprinting planar fabrics are often interpreted as the result of polyphase deformation and described in a scheme of deformation phases d 1 d 2 d n at the same time a number of models have been presented over the last decades that explain how complex and overprinting structures can form by single phase progressive deformation as strain accumulates strain generally accumulates heterogeneously in a deforming region depending on strain intensity and geometry flow parameters rheology and lithology the result is regions of different structural complexity fabrics and fabric orientations that can be sorted into different structural facies such structural pattern should be mapped and presented before defining a scheme of deformation phases and attempts should be made to explain them by a single structural kinematic model such as partitioned transpression only if this is not possible or if independent geochronologic data reveals a more punctuated history should we define an additional tectonic regime and deformation phase multiphase and progressive deformation histories are not mutually exclusive and it is important that both possibilities are considered when describing the deformation history of any complexly deformed region when the concept of deformation phases is employed the number of phases should be minimized and be related to major tectonic event of external character uncritically defining deformation phases can easily generate a complicated discrete deformation history with no link to tectonic reality

geochemical significance of the aromatic hydrocarbon distribution in the bitumens of the puertollano oil shales spain the bituminous series of the puertollano basin consists of three oil shale beds named pa pb and pc from top to bottom in this work results from the study of the aromatic fractions of the bitumens are presented the gas chromatographic traces are dominated by phenanthrene derivatives associated with variable contributions of arborane fernane derivatives and benzohopanes and overall small amounts of chrysene derivatives and secohopanes the compounds can be considered as part of two sub groups the first one consists of those compounds derived from regular hopanes such as secohopanes benzohopanes fully aromatized hopanes and degradation products of hopanes such as alkylated chrysenes and naphthalenes the second group is composed of arborane fernane derivatives and their degradation products such as alkylated phenanthrenes and tetrahydrophenanthrenes both groups of compounds appear to be indicative of a strong bacterial input to the sedimentary organic matter

channel fill coal beds along the western margin of the eastern kentucky coal field abstract four channel filling coal beds from the lower part of the breathitt formation lower middle pennsylvanian late westphalian a were examined palynologically petrographically and geochemically to determine the paleoenvironmental conditions under which these peats accumulated these results were then compared with detailed sedimentological analyses of the strata overlying the coal in the channels to see if any genetic relationship between coal composition and the origin of the overburden could be drawn all four of the coal beds used in this study are located in the western most part of the eastern kentucky coal field and occur at or near the early pennsylvanian unconformity 0 30 m lycospora and densosporites and related crassicingulate taxa e g cristatisporites cingulizonates and radiizonates dominate the studied assemblages with granulatisporites and related trilete sphaerotriangular genera e g leiotriletes and lophotriletes laevigatosporites and schulzospora being common accessory genera petrographically all four coals contain high percentages of vitrinite macerals avg 78 6 mineral matter free moderate amounts of liptinite or exinite macerals avg 14 9 mmf and low percentages of inertinite macerals avg 6 5 mmf strata above the coals consist of dark carbonaceous shales and heterolithic strata that exhibit varying degrees of bioturbation commonly occurring trace fossils include arenicolites monocraterion planolites and skolithos although marine influenced strata as determined from detailed sedimentology and ichnology the study of trace fossils covers all four coal beds they are not uniformly high in total total sulfur content as might be expected rather they are extremely variable ranging from 1 9 dry basis total sulfur ash yields are also variable ranging from 6 2 54 3 dry basis it is probable that the origin of the very first sediments covering the peat as well as the amount of brackish water influence during peat accumulation were important factors in determining the total sulfur content of the resultant coal initial sedimentation of fresh water clays and silts may have acted as a barrier to downward percolation diffusion of sulfate bearing waters or may have served as a site for sulfide formation thereby keeping the total sulfur content of the underlying coal low if initial sedimentation was of brackish or marine origin as indicated by bioturbated laminae directly above the coal or if the peat was subject to frequent brackish or marine water influence during accumulation then sulfide generation might proceed unchecked resulting in high sulfur coal

folds and the strain ellipsoid a general model abstract a new general model is proposed to account for non orthogonal relationships of fold axes and axial surfaces to the axes of the finite strain ellipsoid descriptions in the literature of such relationships e g plunge variations and transecting cleavage are reviewed and the development of the model is outlined the model is described in which plane strain k 1 or slight flattening strain k 0 71 or slight constrictional strain k 1 85 are imposed on a suite of layers with oblique orientations to the bulk strain axes x y z folds will initiate perpendicular to the direction of shortening in the layer and develop as non material lines moving through the layer by angular migration at geologically realistic finite strains the folds will be transected by xy cleavage in slight flattening strain folds are likely to be cylindroidal with axes not measurably oblique to xy in slight constrictional strain en echelon periclines are predicted with marked transection by cleavage in some examples the interference of two directions of folding will give rise to severe plunge variations and even downward facing although strain markers frequently indicate finite strains in the flattening field this may result from the superimposition of slightly constrictional tectonic strain on compactional flattening

comparison of the petrography palynology and paleobotany of the little fire creek coal bed southwestern virginia u s a abstract two continuous cores that penetrated the lower pennsylvanian little fire creek coal bed in the southwestern coal field in southwestern virginia were sampled and x ray radiographed to determine subunit distinctions comparison of petrographic palynologic and paleobotanic data from the same sample sets from the two cores allowed for comparison of compositional data within the little fire creek coal bed the proximate petrographic palynologic and plant tissue data from two sets of samples indicate a high ash gelocollinite and liptinite rich coal consisting of a relatively diverse paleoflora including lycopsid trees small lycopsids tree ferns small ferns pteridosperms seed ferns and rare calamites and cordaites the relatively very high ash yields 3 80 wt the relatively thin subunits 1 28 cm and the large scale vertical variations in palynomorph floras suggest that the study area was at the edge of the paleopea forming environment as a result most of the compositional correspondences are among those components indicative of degradation or decomposition

ultrasonic compressional and shear velocities in dry clastic rocks as a function of porosity clay content and confining pressure summary for clastic silicate rocks sampled from a rotliegendes well core the velocities up and us were obtained at 10 pressures up to 300mpa using a pulse transmission technique the porosities of all rocks 57 sandstones 26 siltstones five claystones ranged from 0 01 and 0 15 by volume fraction and the clay content varied from less than 0 01 to 0 88 by volume fraction both velocities increase with pressure in the low pressure range the rate of increase is large non linear and is greater for up than for us above 120 mpa both velocities increase linearly velocities porosity and clay content were fitted by least squares regression for pressures of 8 24 60 120 200 and 300 mpa the fractional effect of porosity and clay on the velocities for dry clastic silicate rocks can be described above 120 mpa by u a b ccluy where v is the velocity of the p wave or s wave is the volume fraction of pores and clay is the volume fraction of clay from this it is possible to obtain pressure dependent velocity functions u a pb c exp dp where u is the crack free velocity linear in porosity and clay b is the velocity slope under high pressure u c is the zero pressure velocity and d is related to closure of cracks

constraints on deformation mechanisms during folding provided by rock physical properties a case study at sheep mountain anticline wyoming usa summary the sheep mountain anticline wyoming usa is a well exposed asymmetric basementcored anticline that formed during the laramide orogeny in the early tertiary in order to unravel the history of strain during folding we carried out combined anisotropy of magnetic susceptibility ams anisotropy of p wave velocity apwv and fry strain analyses the results are compared to previously published stress strain data from calcite twins at the microscopic scale and from fracture sets at the mesoscopic scale and are used to discuss the kinematics and mechanics of forced folding the results obtained in sandstone and carbonate lithologies demonstrate a good agreement between 1 the principal axes of the ams and apwv tensors 2 stress strain tensors derived from calcite twins 3 fry strain axes and mesoscopic fracture sets furthermore these tensors are coaxial with the main structural trends of the anticline the differences between ams and apwv fabrics on one hand and the differential stress values of the forelimb and the backlimb on the other hand emphasize how the macroscopic asymmetry of sheep mountain anticline affects the strain pattern at the microscopic scale the data set presented in this paper offers a consistent mechanical scenario for the development of sheep mountain anticline

oxygen and strontium isotopes from fossil shark teeth environmental and ecological implications for late palaeozoic european basins article i nfo fossil shark remains occur in both marine and nonmarine late palaeozoic deposits therefore their palaeo ecology is controversial the oxygen and strontium isotopic composition of biogenic fluorapatite in 179 teeth scales and spines predominantly of hybodontid lissodus and xenacanthiform orthacanthus xenacanthus bohemiacanthus triodus sharks from various late carboniferous moscovian to early permian artinskian basins of europe are used as ecological tracers to decipher diadromous or obligate freshwater lifestyle of the investigated taxa the 18 op values of the different shark teeth range from 11 7 to 20 2 within the different basins with mean values of 16 9 0 5 for the bohemian massif 16 2 0 8 for eastern germany 18 2 1 0 for southwestern germany 18 5 0 7 for southern central spain 17 6 0 4 for