characteristics features and compaction of plant tissues traced from permineralized peat to coal in pennsylvanian coals desmoinesian from the illinois basin abstract plant tissues were traced from coal balls to coal to identify and distinguish their characteristic structures in coal and to determine compaction ratios for specific tissues comparison of average cell sizes of lycopod aerial periderm in coal ball peat and coal gave compaction ratios ranging from 7 1 to 19 1 some of this compaction took place by three dimensional contraction of the periderm so that the shapes of the cells in cross section were not greatly changed compaction ratios of other tissues ranged from 3 1 to 60 1 tissues traced into vitrinite include lycopod stem periderm stigmaria periderm diaphorodendron cortex myeloxylon pennsylvanioxylon wood and bark marattialean fern leaves psaronius outer roots and stigmaria rootlets tissues traced into fusinite or semifusinite include lycopod stem periderm myeloxylon and psaronius inner roots cordaitean leaves cordaianthus and marattialean fructifications were identified in coal and coal balls from the same layer the coal balls were from the herrin springfield and houchin creek coal members of the carbondale formation desmoinesian series pennsylvanian system and an unnamed coal in indiana equivalent to the murphysboro coal member in illinois staunton formation desmoinesian series pennsylvanian system thin sections and etched polished blocks were characterized by light and sem microscopy

the euramerican coal province controls on late paleozoic peat accumulation abstract the ancestral tropical peats and associated strata of the euramerican coal province record the interwoven effects of climate tectonism and eustasy during the late paleozoic many peats formed in foreland and intermontane basins associated with equatorial orogenic belts along the borderlands of euramerica and gondwana while other peats formed in adjacent cratonic basins the resolution of controls on euramerican peat formation requires testing against a well constrained temporal framework the late paleozoic coal age followed the evolution of vascular plants in the late silurian and was associated with assemblage of the pangean supercontinent devonian and early carboniferous peats developed locally the major phase of peat formation commenced in the namurian a and persisted to the end of the stephanian spanning 10 30 ma in different regions of euramerica it is ascribed in part to the residence of northward drifting euramerica within the equatorial rainy belt within individual depocenters basin hydrology was suitable for peatland formation during a period 10 6 10 7 years represented by the stratigraphic distribution of coal measures and termed here the basin fill coal window repeated successions cyclothems of coal siliciclastic and carbonate strata punctuate the coal window and typically represent 10 4 10 5 years these stratal successions are widely ascribed to orbitally driven glacioeustasy although cyclothems that lack marine strata may represent associated climatic shifts cyclothem groupings mesothems of 10 6 years duration are recognised locally and may have eustatic or tectonic causes cyclothems produced by autocyclic events such as delta switching should have durations in the order of 10 3 years the coal beds themselves represent autogenic processes of peat formation over periods of 10 3 10 4 years constrained by longer term allogenic effects recorded in the coal bed are tolerable allogenic events such as fires and floods caused by short term climatic excursions the termination of most mires probably occurred when single or combined allogenic effects surpassed the inherent ability of the ecosystem to adapt

modeling compaction of olivine cumulates in the muskox intrusion we have developed numerical models for compaction of olivine cumulates by simultaneous grain boundary diffusion creep and power law creep the simulation is a coupled model of compaction porous medium flow and heat transport that includes latent heat of fusion and advective heat transport by flow of interstitial liquid it also includes precipitation from interstitial pore liquid and partial melting of cumulates caused by changes in temperature or passage of interstitial melt through regions of different temperature compositions and quantities of liquid and precipitated phases are aetermined from a fractional crystallization simulation using the computer program melts we use these models to simulate the accumulation and crystallization of the muskox intrusion simulations suggest that regardless of their initial state compaction will lithify cumulates into a cohesive mass within meters of the depositional interface upward velocity of interstitial liquid is also much too small to suspend or liquify the crystal column the simulations produced rapidly cooled marginal zones at both top and bottom of the intrusion high rates of compaction are found at the tops and bottoms of cyclic units as a result of both high temperature at the boundary and partial melting caused by upward flow of cooler interstitial liquid as it enters hotter compositionally more primitive cumulates above the cyclic unit contact in contrast upward movement of interstitial liquid into cooler cumulates contrib utes to precipitation both in the upper marginal zone and in the middle region of cyclic units the degree of compaction of cumulates is strongly a function of temperature but if temperature is sufficiently high adcumulates can form in the interior of cumulate bodies by compaction alone

role of the kopili fault in deformation tectonics of the indo burmese arc inferred from the rupture process of the 3 january 2016 mw 6 7 imphal earthquake the burmese arc is a peculiar plate boundary where there exists an eastward subducted indian slab but the current tectonics of the region are predominantly governed by a northward strike slip motion of the indian plate past the burmese plate as evidenced by seismic and global positioning system data the shallower portion of the dipping indian slab is characterized mostly by earthquakes with strike slip type focal mechanisms with roughly northwest and northeast trending fault planes although there is no clear evidence for the choice of rupture planes in the present study we use teleseismic broadband waveforms to model the rupture propagation of an m w 6 7 strike slip earthquake of 3 january 2016 that occurred in the indian city of imphal and infer the fault plane orientation the result indicates a right lateral strike slip motion along a n21 w plane which is confirmed by both waveform fitting and distribution of aftershocks interestingly this earthquake occurred at the intersection of three major faults in this region the churachandpur mao fault bounding the india and burma plates the dauki fault south of the shillong plateau and the kopili fault separating the shillong plateau from the brahmaputra valley this raises various possibilities for interpreting this event however based on the finite fault inversion we infer that this earthquake occurred on the kopili fault running northwest southeast from bhutan himalaya down to the burmese arc and manifested as a right lateral strike slip motion in response to the northward motion of the indian plate and a counterclockwise rotation of the brahmaputra valley we further interpret that the overall deformation in the burmese arc region is accommodated by northward slivering of the eastward subducted indian lithospheric slab along a series of northwest to north south trending right lateral strike slip faults from west to east as the indian plate moves northward past the burma and sunda blocks

s wave velocity structure and site effect parameters derived from microtremor arrays in the western plain of taiwan abstract in this study microtremor array measurements were conducted at 45 sites in the western plain of taiwan the arrays were approximately 30 m or 60 m in radius depending on the site the maximum likelihood frequency wavenumber method was adopted to obtain the phase velocities of rayleigh waves and then a genetic algorithm technique based on an inversion scheme of the fundamental mode of the rayleigh waves dispersion curves was applied to calculate a preliminary s wave velocity vs profile at each site because a layer of thick sediment covers the bedrock in the western plain of taiwan microtremor arrays in this size range cannot estimate the structure of the entire sediment therefore this study implemented further inversion of the horizontal to vertical spectral ratios of the microtremors to estimate the deeper structures up to the bedrock of vs greater than 1000 m s previously logged velocity profiles for different depths at or near our study sites were collected and compared with the vs profiles derived from our microtremor array measurements the results were found to be highly comparable therefore we could delineate the depth distributions for the layer depths for vs 600 m s and 1000 m s in this region the depth for vs 600 m s is approximately 50 m in the piedmont area and approximately 300 m at the coastline moreover the depths for vs 1000 m s increase from 200 m in the piedmont area to approximately 1000 m at the coastline the depths for vs 1 0 km s z1 0 which is an important parameter that accounts for the basin effect in recent ground motion prediction equations are consequently available at the study sites the distribution of z1 0 as a function of vs30 indicates higher similarity to that in japan than in the san francisco bay area

timing of emplacement of the muskox intrusion constraints from coppermine homocline cover strata the muskox intrusion is a middle proterozoic shallow level mafic ultramafic layered intrusion in the northwest corner of the bear province of the canadian shield the intrusion was emplaced into the lower proterozoic akaitcho group and hepburn metamorphic plutonic complex of the wopmay orogen and overlying middle proterozoic coppermine homocline strata to date radiometric paleomagnetic and geochemical evidence has produced only equivocal results concerning the age of the muskox intrusion relative to overlying coppermine river group basalts and mackenzie diabase dykes stratigraphic redefinition of and structural relationships to the cover sequence of the intrusion provide the best available evidence for the age of the muskox intrusion although previously inferred to be a pre dismal lakes group structure the canoe lake fault is here shown to cross cut dismal lakes strata with west side down displacement equivalent to that documented to the south where it offsets the intrusion this relationship suppo

paleoecology of middle pennsylvanian age peat swamp plants in herrin coal kentucky u s a abstract to develop a method for quantifying the vegetation of pennsylvania age coal beds of four coal ball permineralized peat profiles and four coal column samples from the herrin coal bed kentucky no 11 carbondale formation in western kentucky were compared an estimated 89 5 of the coal can be identified botanically compaction ratios for individual tissues were estimated using point counts of organic matter in coal balls the estimated abundances of major plant groups lycopods ferns sphenopsids and pteridosperms in coal balls differ by less than 10 compared to coal after accounting for differential compaction of plant tissues standard deviations in taxonomic and maceral composition among coal columns are generally less than 2 consistent differences in botanical composition were found between benches showing that the method is consistent when applied to sufficient thicknesses of coal it was not possible to make fine scale correlations within the coal bed using the vegetational data either the flora varied considerably from place to place or the method of quantification is unreliable for small increments of coal 5 cm or less in the coal pteridosperm abundance is positively correlated with underlying shale partings this correlation suggests that pteridosperms are favored either by higher nutrient levels or disturbance in the third of four benches in the herrin coal bed a succession from sigillaria containing zones to zones dominated by lepidophloios hallii is interpreted as a shift towards wetter conditions in the other benches the main factors controlling the taxonomic composition appear to have been the relative abundance of nutrients and or the frequency of disturbance as indicated by the relative abundance of partings criteria for distinguishing between domed and planar swamps are discussed these include distribution of partings type of plant succession and changes in plant diversity average plant size preservational quality and sporinite content the infrequency of partings in bench c suggests a peat dome developed while the peat of that bench was accumulating but other evidence either fails to support the development of a peat dome or is ambiguous the maceral composition resembles those of other carboniferous coals which are thought to have formed from planar peat swamps formation of fusain bands appears to be associated with processes occurring above the peat surface such as burning or prolonged oxidative exposure oxidation of accumulated peat is unlikely because fusain bands rarely include more than a single plant

the genesis of coal from the viewpoint of coal petrology abstract the genesis of the microscopic constituents of coal macerals and of maceral associations microlithotypes representing various coal facies is discussed in the light of recent advances that have been made in the study of coals and modern peats peat microscopy especially promoted the understanding of humification and biological gelification both of which are decisive for the genesis of huminites vitrinites in brown coals and hard coals respectively microbial activity during peatification has been documented by chemists microbiologists and petrologists and recently by electron microscopical observations in coals this activity leads to the incorporation of lipid substances into the humic matter and later influences the chemical physical and technological properties of vitrinites geochemical gelification transforms the huminites of brown coals into the vitrinites of bituminous coals and is probably caused by the onset of bitumen generation in coal in this process the hydrogel brown coal is transformed to the bitumogel bituminous coal coal as a source rock for oil has become an important research subject for coal petrologists and oil exploration the formation of more or less liquid bitumen and its later cracking to gaseous hydrocarbons leads to the coalification jumps of the macerals especially liptinites and vitrinites and to the generation of secondary macerals like exsudatinite bitumen and micrinite dead carbon bituminization in coal has been revealed by the use of fluorescence microscopy which also found the presence of new liptinite macerals bituminite fluorinite and exsudatinite and suggests a higher proportion of algal material in coals than was thought earlier the genesis of various types of inertinite macerals will probably become an increasingly important subject of research especially with regard to rank inertinites that seem to attain their high inertinitic reflectance initially during coalification besides the origin of macerals the origin of various coal facies in terms of maceral associations is considered in relation to the palaeogeographic depositional milieu the peat forming vegetation palaeoclimate water and nutrient supply acidity marine and calcareous influence and fire with examples from euramerican carboniferous coals gondwana coals and tertiary brown coals vegetation water and oxygen supply eh conditions are most important for the generation of coal facies vegetation has been reconstructed with the help of palaeobotany including palynology cuticular analysis and wood anatomy in brown coals and with the study of petrified permineralized peats preserved in coal balls the microscopical investigations of botanically recognizable plant remains isolated from coals or accompanying rocks has been especially informative however the results of palynological and cuticular analyses should be evaluated with caution considering the varying resistance of palynomorphs and cuticles and in the case of palynomorphs their possible extrapaludal origin microscopical studies of modern peats that were derived from different types of vegetation growing in different hydrological environments have been very helpful in interpreting coal facies especially in brown coals the much disputed origin of brown coal lithotypes is considered in detail for hard coals there seems to be agreement that coal layers rich in vitrites and liptinite poor clarite were deposited in wet forest swamps that microlayered liptinite rich clarites are sub aquatic humic muds and that inertinite rich durites represent oxidized peats the origin of liptinite rich durites is controversial either subaquatic muds or oxidized peats the latter perhaps from raised bogs a recent trend in the literature is the assumption that many if not all mineable coal seams have been deposited in raised bogs under ombrogenous oligotrophic conditions although raised bogs with a dense arborescent vegetation are known from borneo it seems not probable that most seams which were deposited in foredeeps or steadily sinking graben zones are of ombrogenous origin although a succession from relatively wet and eutrophic to relatively dry and oligotrophic conditions may be true for occasional seams but as in modern peats striking changes of coal facies are commonly caused by hydrological events e g inundations as a consequences of crevasses or of fires that burned the peat the origin of the inertinite rich gondwana coals is discussed in relation to their specific climatic conditions and a comparison with sub arctic peats is recommended coals influenced by marine and calcareous conditions are characterized by high contents of sulfur and pyrite as well as by hydrogen rich vitrinites with a relatively low reflectance and high fluorescence all due to a strong bacterial activity in peats of low acidity proposals for further research are made in the conclusions

regional setting geology and paragenesis of the centennial unconformity related uranium deposit athabasca basin saskatchewan canada the centennial unconformity related uranium deposit represents the first significant uranium mineralization along the snowbird tectonic zone in the south central part of the athabasca basin the deposit is associated with a steeply wnw dipping contact between the virgin schist group and mylonitic granite of uncertain age virgin schist group rocks in the deposit area include phyllites impure quartzite and quartzite medium to coarse grained microcline augen porphyroclasts characterize the granite the quartzite being resistant to weathering forms a paleotopographic high flanked by a paleotalus which formed prior to athabasca group sedimentation diabase petrographically and geochemically similar to the 1 27 ga mackenzie dikes intrudes the mineralized trend along brittle structures in the basement rocks and athabasca group a detailed paragenetic study of the deposit area reveals a protracted history that is related to the episodic reactivation of brittle structures and associated fluid movement along this significant structural corridor retrograde metamorphism converted biotite to chamosite at temperatures between 335 to 350 c weathering caused the breakdown of microcline and the dissolution of quartz prior to erosion and deposition of the athabasca group which started at about 1750 ma compaction and diagenesis resulted in quartz overgrowths and development of a diagenetic clay assemblage of illite and sudoite at temperatures between 150 and 200 c which was broadly synchronous with primary mineralization clinochlore euhedral quartz carbonate and pyrite was developed after the intrusion of the diabase under reducing conditions primarily at temperatures between 270 to 320 c uranium remobilization and alteration of uraninite to coffinite appears to have taken place after the emplacement of the diabase dikes kaolinite and uranophane form last in the paragenetic sequence and probably form at relatively low temperatures

topographic slope as a proxy for seismic site conditions and amplification we describe a technique to derive first order site condition maps directly from topographic data for calibration we use global 30 arc sec topographic data and v s 30 measurements here v s 30 refers to the average shear velocity down to 30 m aggregated from several studies in the u s as well as in taiwan italy and australia v s 30 values are correlated against topographic slope to develop two sets of parameters for deriving v s 30 one for active tectonic regions where topographic relief is high and one for stable shields where topography is more subdued by taking the gradient of the topography and choosing ranges of slope that maximize the correlation with shallow shear velocity observations we can recover to first order many of the spatially varying features of sitecondition maps developed for california our site condition map for the low relief mississippi embayment also predicts the bulk of the v s 30 observations in that region despite rather low slope ranges we find that maps derived from the slope of the topography is often well correlated with other independently derived regional scale site condition maps but the latter maps vary in quality and continuity and subsequently also in their ability to match observed v s 30 measurements contained therein alternatively the slope based method provides a simple approach to uniform site condition mapping

discussion on the concepts in paleoenvironmental reconstruction from coal macerals and petrographic indices abstract organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions this allows the relation of coal composition to mire ecosystems or environments coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments many authors proposed relations between specific maceral assemblages and or micro lithotypes and peat forming environments the key controlling factors which affect peat environment include hydrogeology redox ph vegetation type clastic influx sedimentation and peat accumulation rate etc recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models the main reasons for the failure of the petrographic models are oversimplification of the effects of humification on tissue preservation vs destruction the use of post diagenetic processes e g geochemical gelification in determining depositional environments changes in petrographic composition related to floral evolution geological age rank increase and compaction lack of distinction between different inertinite maceral in some models here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo environmental reconstruction are discussed a multi disciplinary approach including petrography palynology chemistry etc has been recommended which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation

reconstructing sea level change from the internal architecture of stromatolite reefs an example from the mesoproterozoic sulky formation dismal lakes group arctic canada the mesoproterozoic dismal lakes group arctic canada contains a relatively thin yet regionally extensive stromatolitic reef complex that developed subtidally during a major transgression shoaled to sea level and was overlain by intertidal to supratidal carbonate and evaporite strata the september lake reef complex exhibits a complex internal architecture that records the interaction between stromatolite growth and changes in accommodation space derived from both higher order 4th or 5th order parasequence scale changes in sea level and the variable bathymetry of the sea floor reef growth which was initiated during three sea level cycles records progressive marine transgression over depositional lows that were formed during pre reef subaerial exposure and erosion of the underlying strata a fourth sea level cycle represented by spectacular coniform stromatolites with 10 m of synoptic relief marks a more dramatic rise in sea level and establishment of the main reef complex aggradation and ev

the paradox of drowned reefs and carbonate platforms shallow water carbonate platforms and reefs are drowned when tectonic subsidence or rising sea level outpaces carbonate accumulation and benthonic carbonate production ceases drowned platforms are common in the geologic record but they present a paradox if one considers rates of processes involved during the early holocene when sea level rose at rates of 6 000 to 10 000 m yr mm 1 000 yr most reefs and platforms were outpaced by the rising sea during the late holocene with sea level rising 500 to 3 000 m yr in the atlantic caribbean area reefs and platforms started to recover built to sea level and prograded seaward 1 000 m yr is thus a conservative estimate of the average growth potential of modern reefs and platforms independently accumulation rates of prograding platforms in the geologic record suggest growth potential in excess of several hundred microns per year the growth potential of 1 000 m yr exceeds any relative rise of sea level caused by long term processes in the geologic record newly formed ocean crust subsides at a maximum of 250 m yr basin subsidence averages 10 to 100 m yr and sea level rises due to increased sea floor spreading amount to less than 10 m yr rapid pulses of relative rise of sea level or reduction of benthic growth by deterioration of the environment remain the only plausible explanations of drowning the geologic record shows examples of both of these processes global mass extinctions of reefs and platforms occurred in the middle cretaceous eustatic rise due to submarine volcanism or desiccation of a small ocean basin and the late devonian global crisis of ocean environment extraterrestrial cause drowning controlled by regional tectonics prevailed in the jurassic and early cretaceous of the tethyan realm and the drowning of mesozoic platforms in the western north atlantic seems to have been dictated by plate tectonic drift to higher latitudes

the conformable emplacement of the bushveld mafic rocks along a regional unconformity in the transvaal succession of south africa abstract a previously unrecognized regional unconformity occurs in the proterozoic transvaal succession of the kaapvaal province of southern africa the predominantly marine and siliciclastic rocks of the lower two thirds of the pretoria group are unconformably overlain by a terrestrial and largely volcanic sequence the most voluminous portion of which is the rooiberg felsite if the bushveld complex is mentally subtracted from map patterns the rooiberg felsite also locally overlies pre pretoria sequences and the archean crystalline basement the bushveld complex is not lopolithic as commonly supposed instead regionally condordant emplacement of the complex along the unconformity explains both the seemingly discordant footwall features and the lack of pretoria and older strata other than a few xenoliths in the hanging wall the lack of any geochemical evidence for major crustal contamination of bushveld magmas precludes disposing of any such hanging wall strata by wholesale assimilation the bushveld complex the unconformity and the enclosing strata are synformally folded making the bushveld appear to be lopolithic due to this folding and multiple periods of erosion the original extents of the bushveld complex the unconformity and the enclosing strata are now much reduced other smaller mafic intrusions along or immediately below the same regional unconformity probably are bushveld related

phyterals of humic coals in the u s s r abstract the results of a study of plant remains found in coals of devonian to neogene age which were studied mainly by the method of phyteral analysis are presented most of phyterals discussed and illustrated in this paper are from coal basins in the u s s r however a discussion of occurrences of phyterals in coal basins worldwide is also included middle devonian coals contain fungal remains and phyterals of the enigmatic vascular plant orestovia the most characteristic phyterals of euramerican carboniferous coals are the following periderm of stems and rhizomes of lepidophytes wood and cortex of gymnosperms of uncertain systematic position rachides of pteridosperms and fructifications of spore bearing plants vitrinized phyterals predominate over fusinized phyterals in carboniferous coals in permian coals of gondwana and angarida vitrinized and fusinized woods bark tissues and leaves of pycnoxylic gymnosperms are characteristic phyterals differences in phyteral composition of early and late permian coals indicate that phyterals from vitrinized leaves were more dominant in late permian coals triassic coals rarely contain phyterals of known affinity jurassic and early cretaceous coals are similar in phyteral composition periderm and cork of conifers and ginkgoaceous plants are typical phyterals phyterals of vitrinized and fusinized gymnospermous wood played a significant role in these coals as well leaf phyterals usually compose layers of the paper and fall of leaves coals distinctive characteristics of phyteral composition of cenozoic coals are 1 wide distribution of lignitized woods 2 constant presence of well identified and very specific root remains 3 high content of plant attritus 4 commonly occurring and distinctive fungal phyterals further study of coal phyterals is suggested for correlation of coal seams and coal bearing strata and for the prediction of coal quality

the mazon creek lagerstatte a diverse late paleozoic ecosystem entombed within siderite concretions one of the best records of late paleozoic ecosystems the mazon creek lagerstatte is world famous for its striking flora and fauna preserved within siderite concretions distinct from other late carboniferous concretionary lagerstatten because of the remarkable fidelity of soft tissues and pigments that are frequently preserved the mazon creek has seen a revival in investigations during the last 10 years using modern palaeontological techniques however many of these modern investigations build upon a literature that incorrectly interprets the palaeoenvironment of the mazon creek and the separate biotas there is a lack of evidence to support a distinct freshwater fauna here we present a detailed overview of the mazon creek lagerstatte including the palaeoenvironmental conditions organisms present and the complex taphonomic processes involved in fossil formation investigation into the formation of siderite concretions and the complex taphonomic processes controlling soft bodied preservation are still continuing but are reviewed in detail

incorporating the local faults effects in development of seismic ground motion hazard mapping for the peninsular malaysia region abstract the probabilistic seismic ground motion hazard maps for the peninsular malaysia region have been developed by the present study despite the earlier seismic hazard maps for this region which were proposed only based on far field sumatran seismic sources this study has attempted to present the new maps using the combination of the local faults within the region sumatran fault and sumatran subduction source zones the composite earthquake catalogue of the study region has been extended to cover an area limited by 10 s 10 n latitude and 90 110 e longitude with the period from 1900 to 2014 the seismic source zones were categorized into subduction and fault sources line area and background source models were used to model the seismic sources with variable characteristics along them in order to consider the epistemic uncertainty logic tree framework was used to incorporate basic quantities such as different source modelling maximum magnitudes and ground motion prediction equations gmpes the hazard maps are presented over a 12 5 km grid in terms of peak ground acceleration pga for 10 and 2 probabilities of exceedance in 50 years corresponding to 475 and 2475 years return periods rp respectively the proposed new hazard maps give the expected ground motions based on the extended earthquake catalogue upgraded seismic source parameters and more compatible gmpes than applied in the development of previous hazard maps the estimated pgas on rock site condition across the peninsular malaysia region for rp475 and 2475 years are in the range of 1 0 10 0 g and 2 0 20 0 g respectively the horizontal elastic acceleration response spectra on different soil site conditions have been also presented for the region of interest following the principles of eurocode 8 through the calculated uniform hazard spectra

ground motion parameters in shillong and mikir plateau supplemented by mapping of amplification factors in guwahati city northeastern india abstract ground motion parameters for shillong mikir plateau of northeastern india are examined empirical relations are obtained for ground motions as a function of earthquake magnitude fault type source depth velocity characterization of medium and distance correlation between ground motion parameters and characteristics of seismogenic zones are established simultaneously new empirical relations are derived for attenuation of ground motion amplitudes correlation coefficients of the attenuation relations depend on the site classifications that are identified based on average shear wave velocity and site response factors the attenuation relation estimated for logarithmic width of mikir plateau found to be a little bit higher than that of shillong plateau both for soft and hard ground which accounts for geometrical spreading and anelastic attenuation simultaneously validation are made studying the seismic microzonation process related to geomorphological geological subsurface features for thickly populated guwahati city of india under threat from scenario earthquake

mechanical models for dikes a third school of thought abstract geological and geophysical data from continental volcanic centers and giant radial swarms and from oceanic shield volcanoes and rift zones indicate that dikes propagate laterally for distances that can be 10 to over 100 times their height what traps dikes within the shallow lithosphere and promotes these highly eccentric shapes gravity induced stress gradients in the surrounding rock and pressure gradients in the magma are the primary loading mechanisms pressure gradients due to magma flow are secondary to insignificant because the flow direction is dominantly horizontal this configuration of vertical blade shaped dikes with horizontal dike propagation and magma flow is fundamentally different from the two dike model configurations described in a recent review paper as two schools of thought for mechanical models of dikes in school i a dike is disconnected from its source and ascends under the influence of buoyancy in school ii a dike is connected to a magma reservoir and is driven upward by magma flux from the source we review the geological and geophysical data supporting the vertical dike horizontal flow propagation configuration and suggest the abundance and veracity of these data in many different geological settings and the modeling results that address this physical process warrant adding this as a third school of thought a new analytical solution for the boundary value problem of a homogeneous isotropic and linear elastic solid with a vertical fluid filled crack is used to investigate the effects of gravitationally induced stress and pressure gradients on the aperture distribution dike tip stress intensity and stable height model results indicate that in a homogeneous crust dikes can achieve stable heights greater than a kilometer only if the host rock fracture toughness k ic 100 mpa m 1 2 however density stratification of the crust is an effective mechanism for trapping kilometer scale dikes even if the host rock is very weak k ic 0 this analysis may explain why vertical dikes propagate laterally for great distances but reside within a narrow range of depths in the crust

site amplification factors in central and southern california determined from coda waves abstract site amplification factors at frequencies of 1 5 3 6 and 12 hz were determined for 158 stations of the southern california seismic network scsn from coda waves of 306 local earthquakes using a recursive stochastic inverse method our results for southern california are consistent with those of central california obtained by su et al 1992 in that the site amplification at a station is systematically related to the surface geology of the station site the site amplification is high for young quaternary sediments and decreases with increasing geologic age at all frequencies between 1 5 and 12 hz this decreasing rate is higher for younger rock sites gradually becomes lower with increasing geologic age and appears to be insignificant when the site reaches mesozoic age or older the relationship between site amplification and geologic age obtained for southern california agrees with that for central california amplification factors at 158 sites in southern california were combined with those at 132 sites in central california through a common reference site the result is a unique data base of site specific uniformly referenced amplification factors throughout central and southern california

site classification for national strong motion observation network system nsmons stations in china using an empirical h v spectral ratio method abstract reliable site classification of the stations of the china national strong motion observation network system nsmons has not yet been assigned because of lacking borehole data this study used an empirical horizontal to vertical h v spectral ratio hereafter hvsr site classification method to overcome this problem first according to their borehole data stations selected from kik net in japan were individually assigned a site class cl i cl ii or cl iii which is defined in the chinese seismic code then the mean hvsr curve for each site class was computed using strong motion recordings captured during the period 1996 2012 these curves were compared with those proposed by zhao et al 2006a for four types of site classes sc i sc ii sc iii and sc iv defined in the japanese seismic code jra 1980 it was found that an approximate range of the predominant period t g could be identified by the predominant peak of the hvsr curve for the cl i and sc i sites cl ii and sc ii sites and cl iii and sc iii sc iv sites second an empirical site classification method was proposed based on comprehensive consideration of peak period amplitude and shape of the hvsr curve the selected stations from kik net were classified using the proposed method the results showed that the success rates of the proposed method in identifying cl i cl ii and cl iii sites were 63 64 and 58 respectively finally the hvsrs of 178 nsmons stations were computed based on recordings from 2007 to 2015 and the sites classified using the proposed method the mean hvsr curves were re calculated for three site classes and compared with those from kik net data it was found that both the peak period and the amplitude were similar for the mean hvsr curves derived from nsmons classification results and kik net borehole data implying the effectiveness of the proposed method in identifying different site classes the classification results have good agreement with site classes based on borehole data of 81 stations in china which indicates that our site classification results are acceptable and that the proposed method is practicable

high vp vs ratio saturated cracks or anisotropy effects 1 we measured vp vs ratios of thermally cracked westerly granite thermally cracked carrara marble and 4 porosity fontainebleau sandstone for an effective mean pressure ranging from 2 to 95 mpa samples were fluidsaturated alternatively with argon gas and water 5 mpa constant pore pressure the experimental results show that at ultrasonic frequencies vp vs ratio of water saturated specimen never exceeded 2 15 even at effective mean pressure as low as 2 mpa or for a lithology for which the poisson s ratio of minerals is as high as 0 3 calcite in order to check these results against theoretical models we examine first a randomly oriented cracked medium with dispersion but without anisotropy and second a medium with horizontally aligned cracks with anisotropy but without dispersion the numerical results show that experimental data agree well with the first model at high frequency vp vs ratios range from 1 6 to 1 8 in the dry case and from 1 6 to 2 2 in the saturated case the second model predicts both vp sv and vp sh to vary from 1 2 to 3 5 depending on the raypath angle relative to the crack fabric in addition perpendicular to the crack fabric a high vp vs ratio is predicted in the absence of shear wave splitting from these results we argue the possibility that high vp vs ratio 2 2 as recently imaged by seismic tomography in subduction zones may come from zones presenting important crack anisotropy the cumulative effects of crack anisotropy and high pore fluid pressure are required to get vp vs ratios above 2 2 citation wang x q a schubnel j fortin e c david y gueguen and h k ge 2012 high vp vs ratio saturated cracks or anisotropy effects geophys res lett 39 l11307 doi 10 1029 2012gl051742

paradise and herrin lost marginal depositional settings of the herrin and paradise coals western kentucky coalfield abstract this is the fourth installment in a series of papers on the asturian westphalian d disrupted mire margins termed the ragged edge in previous papers and limestone distributions in the herrin baker coal interval in the western kentucky extension of the illinois basin new data indicating in situ peat development and marine influence collected from the first in mine exposure of this interval are presented borehole data from the region are examined in the context of ragged edge exposures and a carbonate platform depositional model for this portion of the illinois basin is presented this shows that deposition of the sequence was influenced both by the underlying sediments and by a marine transgression the former influence is seen in variations in coal and limestone thickness over sandstone filled channels versus over shale bayfill deposits the latter is marked by the progressive upwards loss of coal benches i e the bottom bench of both coals is the most extensive and the herrin coal is more extensive than the overlying paradise coal and by marine partings in both coals further the brecciated margins seen in both coal seams are similar to brecciated peats encountered along the everglades margins of southwest florida overall coal distributions are similar to both those along the everglades margins and those along a transect from the belize coast to ambergis caye

assessment of maximum earthquake potential of the kopili fault zone in northeast india and strong ground motion simulation abstract maximum magnitude mm earthquake in the kopili fault zone of north east india has been assessed using different approaches which are primarily dependent on various parameters such as fault geometry slip rate geodetic moment rate and convergence rate the analyses reveal that the source zone has accumulated strain energy during the last 72 years since 1943 enough to produce a strong earthquake of magnitude 7 on supplementing with the historical data we conclude mw7 3 as the maximum potential earthquake for the kopili source zone such large earthquake on its occurrence may cause widespread significant ground shakings and damage to infrastructures in the study region we therefore also simulated strong ground motion in the form of peak ground acceleration pga for the mw7 3 potential earthquake using empirical green s function egf approach for ten different sites in the analysis an earthquake of magnitude mw6 5 which has been simulated using a recorded mw5 3 earthquake is used as green s function the two step approach is adopted in the simulation process as the required criteria i e moment ratio of

seismic b value anomalies prior to the 3rd january 2016 mw 6 7 manipur earthquake of northeast india abstract spatial variation of seismic b value is estimated in the indo myanmar subduction zone of northeast ne india using the homogeneous part of earthquake catalogue 1996 2015 recorded by international seismological center isc consisting of 895 events of magnitude mw 3 9 the study region is divided into 1 1 square grids and b values are estimated at each grid by maximum likelihood method in this study the b value varies from 0 75 to 1 54 in the region significant variation of low b value in the respective location may indicate high stress accumulation in that region spatial variation reveals intermediate b value anomalies around the epicenter of the mw 6 7 manipur earthquake which occurred on 3rd january at 23 05 utc 4 january 2016 at 04 35 ist the variations of b values are also estimated with respect to depth the low b value associated with the depth range 15 55 km which may imply crustal homogeneity and high stress accumulation in the crust since ne india lies in the seismic zone v of the country this study can be helpful to understand seismotectonics in the region

late carboniferous crustal uplift of the tarim plate and its constraints on the evolution of the early permian tarim large igneous province abstract the early permian tarim large igneous province lip in northwestern china has been related to a mantle plume mostly constrained by petrology and geochemistry however the crustal uplift erosion related to a mantle plume has rarely been addressed in order to improve our understanding of crustal uplift erosion we have studied the stratigraphy and sedimentology of eighty five boreholes outcrops and two seismic profiles the results indicate a regional unconformity and onlap contact between the earliest permian and carboniferous strata with denudation of carboniferous and deposition of earliest permian strata the denudation of carboniferous strata has been divided into three types of erosion deep partial and weak with a deep erosion zone located in northern tarim region east of keping and west of northern tarim which gradually weakens towards the south above the unconformity the early permian pre eruption deposit is thinnest 300 m which is consistent with the spatial distribution of late carboniferous erosion this unconformity represents a spatial distribution of denudation forced by doming uplift erosion at the end of the carboniferous with minimum estimation of its vertical and lateral extent of 887 m and 300 km respectively which are comparable to those of other mantle plume generated lips both the late carboniferous erosion and early permian sedimentary records indicate a crustal uplift event at 300 ma the uplift was short term and approximately dome shaped occurring immediately before the tarim lip 290 ma these results provide new stratigraphic and sedimentological constraints on the role of a mantle plume in the formation early permian tarim lip from a crustal uplift perspective the spatial distribution of denudation suggests that the regions of northern tarim or further north represent the centre of the potential plume head

estimation of site effects and q factor using a reference event a method to determine site effects and the q factor using a reference event is described spectral ratios between pairs of earthquakes and a reference one were written as logarithmic summations in order to obtain individual solutions for the numerators and denominators given the seismic moment and corner frequency for one of the events following the 2 model a source model was assumed to constrain the amplitude of the solution the validity and limitations of this technique were tested on synthetically generated data we analyzed the variances of the results depending on the different number of stations used the amount of noise present in the records and the change in the seismic moment corner frequency and source model of the reference event aftershocks of the 2000 tottori japan earthquake were used to estimate the site effects and q factor in that region two strong motion networks k net and kik net recorded the aftershocks the latter network contained both surface and borehole receivers at every station data were inverted first using only surface records and then using the borehole records from kik net stations in order to study amplitude differences our results suggest that the study area presents a low q value and that there is also amplification at borehole sites manuscript received 18 january 2002

a major fire event recorded in the mesofossils and petrology of the late permian lower whybrow coal seam sydney basin australia abstract petrographic and mesofossil analyses of plies from the late permian lower whybrow coal new south wales australia have revealed a significant fire event in both the swamp setting and the hinterland the fire event is characterised by a change in the maceral composition the seam during this interval being dominated by inertinite especially semifusinite following the fire event the mineral matter content of the coal increases this may be the result of increased run off and erosion in the hinterland due to destruction of vegetation this major fire event is also reflected in a change in the vegetation as represented by the mesofossil content of the seam prior to the fire event the seam contains abundant bisaccate taeniate pollen sporangia and seed like bodies of possible glossopterid affinity these are lost at the ply in which the fire event is recorded though seed like bodies become important again later the fire event also corresponds to a change in the megaspore content of the coal a new species appearing perhaps as a result of hydrological change following this major fire event a mineral rich ply was deposited which contains miospore masses of spores from fern like plants possibly representing a re colonisation event by rhizomorphs after vegetation death this evidence for a major fire and its implications for the origin of inertinites leads to the conclusion that throughout this and other permian gondwana coals fire was an integral part of the temperate mid high latitude southern hemisphere swamp ecosystem

coal and coal bearing strata problems and perspectives for the past 15 years oil of all the fossil fuels has been the most prominent in both geological and non geological literature significant progress has been made on many aspects especially in exploration by employing interdisciplinary approaches to make scientific and economic gains technical advances have allowed exploration to move into more hostile geographical areas the effect on research of this increased exploration effort has been to stimulate new interpretations in several areas of geology especially in sedimentology tectonics geophysics and geochemistry coal has to some extent remained a poor relation effort has been directed to more technical aspects of production and utilization rather than in the investigation of more fundamental aspects concerning its origin in spite of this there has been significant progress in several aspects of coal geology over the past 15 years in addition new geographical areas are opening up for exploration most notably china australia western north america and indonesia the time is right therefore to highlight recent advances in coal research in 1968 following an inter university student conference d g murchison and t s westoll edited an important volume on coal and coal bearing strata which synthesized several important aspects of coal research soon after this the second edition of stach s classic textbook of coal petrology was published stach et al 1975 now in its third edition much is owed to work of m r teichmiiller on coalification and its uses the recent upsurge of interest in coal geology is indicated by the publications of

application of horizontal to vertical spectral ratios of earthquake ground motions to identify subsurface structures at and around the k net site in tohoku japan abstract we propose an optimal way to use horizontal to vertical spectral ratios hvrs for subsurface structure exploration based on the diffuse field concept kawase et al 2011 sanchez sesma et al 2011 this approach is applicable to both earthquake and microtremor ground motions we show here analyses of the observed ground motion data at and around a k net station in miyagi prefecture japan where very large peak horizontal ground acceleration was observed during the earthquake of 11 march 2011 off the pacific coast of tohoku japan we compare hvrs of the strong motions for the mainshock and the largest peak acceleration aftershock with those averaged over tens of weak motions to observe soil nonlinearity effects on the hvrs then we determine detailed velocity profiles from the hvrs at the k net tsukidate station and the temporary aftershock observation sites we find that hvrs can be explained quite well by the identified velocity profiles at all the target sites the observed peak at 9 hz for the averaged weak motion data originates in the topmost layers lying over the engineering bedrock

large and great earthquakes in the shillong plateau assam valley area of northeast india region pop up and transverse tectonics abstract the tectonic model of the shillong plateau and assam valley in the northeast india region the source area for the 1897 great earthquake ms 8 7 and for the four 1869 1923 1930 and 1943 large earthquakes m 7 0 is examined using the high precision data of a 20 station broadband seismic network about 300 selected earthquakes m 3 0 recorded during 2001 2009 are analysed to study the seismicity and fault plane solutions the dominating thrust reverse faulting earthquakes in the western plateau may be explained by the proposed pop up tectonics between two active boundary faults the oldham brahmaputra fault to the north and the dapsi dauki thrust to the south though the northern boundary fault is debated the more intense normal and strike slip faulting earthquakes in the eastern plateau mikir massif and in the assam valley on the other hand are well explained by transverse tectonics at the long and deep rooted kopili fault that cuts across the himalaya and caused the 2009 bhutan earthquake mw 6 3 it is conjectured that the complex tectonics of the shillong plateau and transverse tectonics at the kopili fault make the region vulnerable for impending large earthquake s

imaging subsurface structure of an urban area based on diffuse field theory concept using seismic ambient noise single station ambient noise measurement in campaign mode has of late gained a huge popularity among geo scientists herein we present results of ambient vibration analysis executed in a highly populated urban area covering 47 survey points the resonance frequency estimates range from 0 5 to 3 hz as found from h v taking h v curve as input for retrieving subsurface information we deploy diffuse field assumption dfa theory the obtained shear wave velocity from the inversion of h v curve through dfa approach provides evidence of the complex nature of the subsurface geological structures identifying six characteristic 2d cross sections of the entire area we attain prevalence of a low velocity intermediate layer with velocity ranging from 128 192 m s on the contrary a relatively high velocity layer is also obtained 279 471 m s which can be treated as sedimentary deposits may be for some sites as basin basement the attained results when extended to a 3d shear wave profile tally excellently with estimated frequency distribution and its corresponding links with depth wise strata accompanied by a topographical profile of the surveyed locations all findings are comprehensively analyzed and interpreted as a proof of concept of implementation of dfa approach towards retrieving subsurface information

reassessment of the evidence for primary fusinite and degradofusinite abstract insight into the origin of fusinite was gained using late carboniferous polished coal balls permineralized peat from the new castle coal bed alabama u s a the union coal bed lancashire england and the calhoun coal bed illinois u s a two types of fusinite were studied primary fusinite fusinite formed without undergoing charring or oxidation and degradofusinite fusinite formed due to decay or degradation evidence for primary fusinite in vascular plants previously relied on color in coal ball thin sections for maceral identification color is shown to be an unreliable guide to maceral identity in coal ball thin sections other evidence for primary fusinite from vascular plants is scant abundant fungi with vitrinitic reflectivity were found in coal balls whereas none with fusinitic reflectivity were found although genuine fungal sclerotinite does exist the occurrence of fungal sclerotinite does not prove that fungal sclerotinite is primary fusinite but only that fungi can be fusinitized both lycopod periderm with fungal decay features and coprolites have vitrinitic reflectivity in coal balls these tissues should have had fusinitic reflectivity if decay or degradation results in fusinitization these results therefore cast doubt on the existence of degradofusinite charcoal and decayed tissues show features that may allow them to be distinguished in some cases in charcoal the secondary cell walls of adjacent cells together with the middle lamellae are usually fused into a single homogeneous unit in decayed tissues the middle lamellae is preferentially decayed which can result in the separation of adjacent cells some prominent illustrations of degradofusinite show fusion of the cell walls of adjacent cells indicating an origin by charring this indicates that presently accepted criteria for recognizing degradofusinite are inadequate even if degradofusinite does exist some evidence for degradofusinite does exist but the key illustration as published teichmuller 1950 1989 does not demonstrate the existence of degradofusinite

evaluating the extent to which wildfire history can be interpreted from inertinite distribution in coal pillars an example from the late permian kuznetsk basin russia abstract inertinite charcoal distributions in two randomly sampled in situ coal pillars seams 78 and 88 from the late permian kuznetsk basin siberia were analysed using petrographic techniques to determine palaeowildfire histories fire occurrence type and return interval in situ coal pillars are judged to be essential for this type of research as they retain information on the original inertinite distribution and maceral clast size ranges which can never be obtained from the crushed coals typically used for petrographic analysis the seams represent an ombrotrophic mire seam 78 and mire with mire lake seam 88 depositional settings but both environments show the same pattern of fire history charcoal is present in all lithotype units in both pillars both pillars contain episodic charcoal horizons representing local surface fires within the peat forming environment interspersed with frequent regional background fire events as shown by small scattered inertinite this paper presents an approach to calculating fire return intervals fri in these coal pillars by removing the thickness of less compactable charcoal horizons before calculating original duration of peat formation this is achieved by using a range of peat accumulation rates and peat to coal compaction ratios resultant mean fri ranges from 7 years extremes 0 5 to 143 years for a lithotype unit containing 4 horizons to 70 years extremes 5 to 1550 years for a lithotype unit with 2 horizons the mid range values both suggest shorter fire return intervals than seen in modern peat forming environments

assessment of seismic site conditions a case study from guwahati city northeast india the 1897 great shillong earthquake revealed considerable seismic susceptibility in guwahati city such as soil liquefaction landslides and surface fissures in an attempt to quantify the seismic vulnerability of the city based on geological seismological and geotechnical aspects concerning seismic site characterization in depth analysis was performed using a microtremor survey with recordings of five small to moderate magnitude 4 8 mb 5 4 earthquakes that occurred in 2006 and geotechnical investigations using the standard penetration test spt additionally the basement topography was established using vertical electrical resistivity sounding and selected drill hole information region specific relationships are derived by correlating the estimated values of predominant frequency shear wave velocity and basement depth indicating conformity with the predominant frequency distribution and the basin topography underlain by a hard granitic basement most parts of the city adhere to the predominant frequency range of 0 5 3 5 hz setting aside areas of deep sediment fills or hilly tracts suggesting that the existing moderate rise rc buildings in the territory are seismically vulnerable furthermore the geotechnical assessment of the soil liquefaction potential reveals widespread susceptibility across the terrain eventually a site classification map of the city is prepared following the national earthquake hazard program nehrp provision the average site amplification factor from geotechnical modeling for site class d is about 3 in the frequency range of 2 4 hz in addition earthquake data yield an average site amplification factor of 4 6 in the frequency range of 1 2 5 0 hz at the seismic stations located in site class e and f high site amplifications of around 5 5 and 7 5 at 2 hz respectively are observed at amtron and irrig seismic stations which are located in the proximity of precambrian rocks indicating probable basin edge effects scattering and diffraction of incident energy interplay of dispersed valleys surrounded by small hillocks in the study region is likely to induce micro basin effects where the sediment thickness depth vis a vis predominant frequency and basin geometry in conjunction play pivotal roles in the augmentation of site response

geochemistry and petrogenesis of basaltic rocks from coppermine river area northwest territories proterozoic basaltic flows 2000 m thick and associated dykes and sills from the coppermine river area northwest territories have chemical compositions typical of continental tholeiites the low mg fe ratio and abundances of ni and cr indicate that the lavas were extensively fractionated prior to extrusion the variations of incompatible elements such as k rb ree y zr nb and th suggest that the rocks were affected by interaction with continental crust the samples least affected by contamination have trace element compositions very similar to those of p type mid ocean ridge basalts it is suggested that continental tholeiites have been generated from the same source as p type oceanic tholeiites and geochemical features such as the enrichment of some lithophile elements in many of these rocks may be related to crustal contamination the variations within the volcanic pile of the coppermine river area are related to those of an exposed part of the muskox layered intrusion

coal petrology and the origin of coal macerals a way ahead the development of coal petrology and the establishment of a nomenclatural system have proved of major use both for the industrial utilization of coal and for the development of a broad understanding of coal formation and diagenesis the development over the past 30 years however of nomenclature that includes aspects of plant origin and process is a retrograde step e g pyrofusinite degradofusinite and funginite equally problematic is the use of prescriptive formulae to indicate coal origins this paper reviews some of the problems involved with coal petrology as it is usually practiced in addition new advances in organic geochemical techniques have led to a fuller understanding of the relationship of plants and coal macerals recent research on the origin of coal macerals is presented and there is a discussion of the problems and challenges facing coal petrologists a holistic approach to studies of the origin of coal and coal macerals which includes not only petrographic but also chemical and biological studies is advocated d 2002 elsevier science b v all rights reserved

regional variation of coda q in kopili fault zone of northeast india and its implications abstract kopili fault has been experiencing higher seismic and tectonic activity during the recent years these kind of active tectonics can be inspected by examining coda wave attenuation and its dependence with frequency exploiting single back scattering model we have endeavored to measure coda q and its associated parameters such as frequency dependent factor n and attenuation coefficient covering seven lapse time windows spanning from 30 to 90 s and central frequencies 1 5 3 5 6 9 and 12 hz the average estimated values of qc increase s with frequency and lapse time window from 114 at frequency 1 5 hz to 1563 at frequency 12 hz for 30 s window length and from 305 at frequency 1 5 hz to 2135 at frequency 12 hz for 90 s window length the values of q0 and n are also estimated for the entire kopili fault zone for this study region the q0 values vary from 62 to 348 and n varies from 0 57 to 1 51 within the frequency range 1 5 to 12 hz furthermore depth variation of attenuation of this region reveals that there is velocity anomaly at depth 210 220 km as there arises sharp changes in and n which are supported by available data reported by other researcher for this region finally we have tried to separate the intrinsic and scattering attenuation for this area it is observed that the entire region is dominated by mainly scattering attenuation but we can see an increase in intrinsic attenuation with depths in two stations namely tzr and bkd furthermore the obtained results are comparable with the available global data

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

from peat bog to lignite seam a new method to calculate the consolidation coefficient of lignite seams wielkopolska region in central poland only one quantitative method is described in the literature to estimate the consolidation coefficient of lignite seams more studies concentrate on the compaction of plant tissues which explains why the obtained results are overestimated moreover most studies do commonly not determine the consolidation of the whole peat bog but usually those of some of its elements only we propose a new approach which conceptually is fairly close to the hager et al fortschr geol rheinld westf 29 319 352 1981 method our method has been tested on an example of the first middle polish lignite seam and the second lusatian lignite seam from some wielkopolska lignite deposits in central poland the consolidation coefficients cc range between 2 34 and 2 56 for the second lusatian lignite seam and between 1 80 and 2 14 for the first middle polish lignite seam

coal facies studies in the eastern united states coals in the eastern united states east of the mississippi river have been the subject of a number of coal facies studies going back to the 19th century such studies would not necessarily fall within a strict modern classification of coal facies studies but if a study encompassed some aspects of paleobotany palynology petrology geochemistry or sedimentology we assumed that some data and interpretations may be of use in evaluations of the facies references are presented as a guide for further research with annotation in the tables

the sedimentary record of mantle plume uplift preceding eruption of the neoproterozoic natkusiak flood basalt strata of the neoproterozoic shaler group on victoria island in nw canada reveal stratigraphic and sedimentological features that are interpreted to be a response to differential crustal uplift immediately preceding emplacement of the 723 ma franklin gabbro sills and their extrusive equivalents the natkusiak formation flood basalts volcanism was coeval with sedimentation as indicated by loading features developed on the kuujjua formation a fluvial braidplain quartzarenite that underlies the lowermost basalt flow of the natkusiak formation in the sw part of minto inlier the kuujjua formation represents the top of an emergent cycle that began with deposition of intertidal carbonates followed by supratidal sabkha carbonates and sulphate evaporites of the underlying kilian formation the kuujjua formation thins and pinches out toward the northeast and there is erosional beveling of the upper kilian beneath it in the ne part of minto inlier the kuujjua and upper kilian are absent and the natkusiak form

delineation of subsurface profiles beneath the kopili fault zone in northeast india utilizing coda portion abstract the kopili fault kf zone is witness to many seismic activities including the 1869 earthquake 7 8 ms the 1943 earthquake 7 3 ms and recent 2016 earthquake 6 7 mw which occurred at certain time intervals considerable portion of kf zone and its neighbouring is characterized by alluvial soils which have higher potential of trapping seismic waves this leads to intense amplification of ground shaking necessitating a detailed study of subsurface profile beneath kf the h v spectral ratio of strong motion recordings is an effective tool to evaluate such nonlinear site responses and to develop a subsurface velocity profile is an important step toward hazard mitigation in this work we used 14 seismic stations nearby this fault to construct the subsurface profile this study suggests that h v ratios obtained from coda portion of seismogram are almost independent of the coda window length we applied diffuse field concept to produce an inverted s wave as well as p wave velocity profile the inverted profiles show significant correlation with the underlying site class as well as exhibit an excellent match with already reported attenuation quality factors for this region for few selected sites inferred velocity estimates become 500 m s at a depth of 25 m or shallower interestingly it is observed that two nearby receiving sites are characterized by different shear wave velocity profiles at shallower depths however in deeper depths they are found to converge all results are comprehensively analyzed and their implications are accordingly outlined

place vs time and vegetational persistence a comparison of four tropical mires from the illinois basin during the height of the pennsylvanian ice age abstract coal balls were collected from four coal beds in the southeastern part of the illinois basin collections were made from the springfield herrin and baker coals in western kentucky and from the danville coal in southwestern indiana these four coal beds are among the principal mineable coals of the illinois basin and belong to the carbondale and shelburn formations of late middle pennsylvanian age vegetational composition was analyzed quantitatively coal ball samples from the springfield herrin and baker are dominated by the lycopsid tree lepidophloios with lesser numbers of psaronius tree ferns medullosan pteridosperms and the lycopsid trees synchysidendron and diaphorodendron this vegetation is similar to that found in the springfield and herrin coals elsewhere in the illinois basin as reported in previous studies the danville coal sample which is considerably smaller than the others is dominated by psaronius with the lycopsids sigillaria and synchysidendron as subdominants coal balls from the springfield coal were collected in zones directly from the coal bed and their zone by zone composition indicates three to four distinct plant assemblages the other coals were analyzed as whole seam random samples averaging the landscape composition of the parent mire environments this analysis indicates that these coals separated from each other by marine and terrestrial clastic deposits have essentially the same floristic composition and thus appear to represent a common species pool that persisted throughout the late middle pennsylvanian despite changes in baselevel and climate attendant the glacial interglacial cyclicity of the pennsylvanian ice age patterns of species abundance and diversity are much the same for the springfield herrin and baker although each coal both in the local area sampled and regionally has its own paleobotanical peculiarities despite minor differences these coals indicate a high degree of recurrence of assemblage and landscape organization the danville departs dramatically from the dominance diversity composition of the older coals presaging patterns of tree fern and sigillaria dominance of late pennsylvanian coals of the eastern united states but nonetheless built on a species pool shared with the older coals

residence time of diffuse waves in the crust as a physical interpretation of coda q application to seismograms recorded in mexico summary we consider a simple model for elastic wave propagation in the earth s litho sphere consisting of a heterogeneous and scattering crust overlying a homogeneous mantle that is we neglect backscattering from the upper mantle this rough condition is not strictly valid everywhere but this model allows us to investigate the effects of variations of diffracting properties between crust and mantle on the coda decay the free parameters describing the wave propagation are the mean free path of the waves and the intrinsic absorption in the crust in the framework of the radiative transfer theory we treat accurately jumps in s wave speed and the mean free path at the moho without intrinsic absorption this configuration yields a synthetic coda decay 1 texp 2 ft qc a form similar to that proposed by aki chouet 1975 to parametrize the observations the exponential decay in our purely elastic model is due to the partial leakage of diffuse energy into the mantle in order to test the applicability of our model we have determined the coda q parameter qc in the 1 15 hz frequency band from data recorded at four stations in mexico in the low frequency regime around 1 hz we suggest that the energy leakage significantly affects coda q whilst at higher frequencies around 10 hz the anelastic attenuation dominates a weak intrinsic absorption expressed by a frequency independent parameter qi of about 1000 accounts satisfactorily for the observed qc values in the whole frequency range our very simple model has only two free parameters and offers an attractive alternative physical interpretation of coda q in mexico this model is sufficient to interpret the coda observations according to our model in regions where the mean free path is much larger than the crustal thickness weakly heterogeneous crust the leakage effect should be small and the observed qc will mainly be due to the intrinsic absorption on the other hand when the mean free path is of the order of the crustal thickness strongly heterogeneous crust we predict a strong sensitivity of the decay rate of the coda to the crustal thickness this dependence may be important for the interpretation of the regional variations of coda q we propose introducing a new parameter d the residence time of diffuse energy in the crust which is physically more meaningful than a quality factor to quantify the leakage effect

a new method to estimate accumulation rates of lignites in the eocene buchanan lake formation canadian arctic abstract exceptionally well preserved eocene plant fossils occurring in leafy litter mats from the buchanan lake formation canadian arctic make it possible to estimate the accumulation rate of the lignite this method is based on the assumption that the projected leaf surface area of individual tree species per unit of ground surface area leaf area index is more or less constant the calculated accumulation rate of 1 6 mm year has been corrected to the minimum accumulation rate of 0 8 mm year by considering the effects of organic decomposition since the compaction ratio of the leaf lignite is difficult to estimate correct comparison with accumulation rates of modern and quaternary peats that have been determined by using 14c ages is impossible however the accumulation rate calibrated in the peat stage of coalification by using the compaction ratio of woods embedded in the leaf lignite is within the range of accumulation rates determined for modern and quaternary peats

determination of shallow shear wave velocity profiles in the cologne germany area using ambient vibrations summary we have used both single station and array methods to determine shallow shear velocity site profiles in the vicinity of the city of cologne germany from ambient vibration records based on fk analysis we assume that fundamental mode rayleigh waves dominate the analysed wavefield in the frequency range of 0 7 2 2 hz according to this view a close relation exists between h v spectral ratios and the ellipticity of the contributing rayleigh waves the inversion of the shape of h v spectral ratios then provides quantitative information concerning the local shear wave velocity structure however based on tests with synthetic data believed to represent a typical situation in the lower rhine embayment dispersion curves were found to provide stronger constraints on the absolute values of the velocity depth model than the ellipticities the shape of the ellipticities was found to be subject to a strong trade off between the layer thickness and the average layer velocity we have made use of this observation by combining the inversion schemes for dispersion curves and ellipticities such that the velocity depth dependence is essentially constrained by the dispersion curves while the layer thickness is constrained by the ellipticities in order to test this method in practice we have used array recordings of ambient vibrations from three sites where the subsurface geology is fairly well known and geotechnical information is at least partially available in order to keep the parameter space as simple as possible we attempted to fit only a single layer over a half space model however owing to earlier studies from the region we assume a power law depth dependence for sediment velocities for all three sites investigated the inversion resulted in models for which the shear wave velocity within the sediment layer both in absolute value at the surface and in depth dependence are found to be remarkably similar to the results obtained by budny from downhole measurements this is strong support for the interpretation of h v spectral ratios as rayleigh wave ellipticities for all three sites the predicted sh wave site amplification factors at the fundamental frequency are of the order of 5 6 with a slightly smaller value south of cologne

the effects of attenuation and site on the spectra of microearthquakes in the shillong region of northeast india microearthquake spectra from the shillong region are analyzed to observe the effect of attenuation and site on these spectra the spectral ratio method is utilized to estimate the q values for both p and s waves in the subsurface layer wherein the ratio of spectral amplitudes at lower and higher frequencies are taken into consideration for three stations at varying epicentral distances average estimates of qp and qs are 178 and 195 the ratio of qs to qp is estimated to be greater than 1 in major parts of the shillong area which can be related to the dry crust prevailing in the shillong region typically the variation in corner frequencies for these spectra is inferred to be characteristic of the site simultaneously observations from spectral content of local earthquakes recorded at two different stations with respect to the reference site yield greater amplification of incoming seismic signals in the frequency range of 2 5 hz which is found to be well supported by the existing local lithology pertinent to that region

watching the wind seismic data contamination at long periods due to atmospheric pressure field induced tilting abstract following the installation of a new broadband seismic station near the pacific coast of the olympic peninsula washington the pacific northwest seismic network recorded elevated background seismic noise at periods exceeding 30 s we observed power spectral density variations of about 15 20 db in the horizontal component seismograms between times of high and low noise and differences of up to about 25 db between the horizontal and vertical components during noisy intervals the amplitude of the signal at long periods exhibited clear correlations with cyclic daytime fluctuations of air temperature and wind speed our observations provided measurable evidence that the variations of the local atmospheric pressure field associated with local wind systems represents an effective source of ground displacements and rotations the rotational component of the pressure field induced motion is recorded by horizontal component seismometers that below their low frequency corner are sensitive to surface tilts the response of seismometers to ground rotations is characterized by a transfer function which we use to estimate the amplitude of tilt we measured a pressure field induced surface tilt of the order of several tenths of rad based on simple modeling tilt contamination is expected to attenuate rapidly with depth and to become negligible just a few hundreds of meters below the surface removal of this unwanted effect from seismograms remains a challenging task as the details of tilting depend on the nonstationary character of the pressure field the compliance of the near surface to pressure variations and the design and construction of the seismic station online material animated time sequenced plots of daily seismic noise pdfs

site correction of a high frequency strong ground motion simulation based on an empirical transfer function abstract in this study an empirical transfer function etf which is the spectrum difference in fourier amplitude spectra between observed strong ground motion and synthetic motion obtained by a stochastic point source simulation technique is constructed for the taipei basin taiwan the basis stochastic point source simulations can be treated as reference rock site conditions in order to consider site effects the parameters of the stochastic point source approach related to source and path effects are collected from previous well verified studies a database of shallow small magnitude earthquakes is selected to construct the etfs so that the point source approach for synthetic motions might be more widely applicable the high frequency synthetic motion obtained from the etf procedure is site corrected in the strong site response area of the taipei basin the site response characteristics of the etf show similar responses as in previous studies which indicates that the base synthetic model is suitable for the reference rock conditions in the taipei basin the dominant frequency contour corresponds to the shape of the bottom of the geological basement the top of the tertiary period which is the sungshan formation two clear high amplification areas are identified in the deepest region of the sungshan formation as shown by an amplification contour of 0 5 hz meanwhile a high amplification area was shifted to the basin s edge as shown by an amplification contour of 2 0 hz three target earthquakes with different kinds of source conditions including shallow small magnitude events shallow and relatively large magnitude events and deep small magnitude events relative to the etf database are tested to verify site correction the results indicate that etf based site correction is effective for shallow earthquakes even those with higher magnitudes but is not suitable for deep earthquakes finally one of the most significant shallow large magnitude earthquakes the 1999 chi chi earthquake in taiwan is verified in this study a finite fault stochastic simulation technique is applied owing to the complexity of the fault rupture process for the chi chi earthquake and the etf based site correction function is multiplied to obtain a precise simulation of high frequency up to 10 hz strong motions the high frequency prediction has good agreement in both time and frequency domain in this study and the prediction level is the same as that predicted by the site corrected ground motion prediction equation

dispersed angiosperm cuticles their history preparation and application to the rise of angiosperms in cretaceous and paleocene coals southern western interior of north america abstract cuticle the decay resistant outer layer of leaves and young stems provides a reliable means of identifying fossil plant remains and reflects the vegetative adaptations of plants to climate and other environmental parameters the study of dispersed angiosperm cuticles originated prior to world war ii and has focused on the origin and paleoecology of coal activity in dispersed cuticles reached a high point during the 1950s and 1960s with the study of tertiary lignites in central europe then subsided in central europe as workers from other regions expanded the technique to other time periods and geographic regions data from dispersed cuticles augment data from palynomorphs because dispersed cuticles originate from a different generation of the vascular plant life cycle and have different taphonomic histories because the analysis of dispersed angiosperm cuticles is unfamiliar to many geologists methods for the analysis and preparation of dispersed angiosperm cuticles are detailed in an appendix dispersed cuticle assemblages from coals in the upper albian longford member of the kiowa formation and the maastrichtian paleocene raton formation of the southern western interior provide new constraints on the times that angiosperms entered coal swamps and rose to dominance the kiowa assemblages indicate that angiosperms first entered coal swamp environments by the late albian while the raton assemblages indicate that angiosperms dominated primary productivity in some subtropical coal swamps by the late maastrichtian angiosperms in kiowa coals probably comprised pioneer species in conifer dominated vegetation the most common family of angiosperms was chloranthaceae angiosperms in upper maastrichtian raton coals comprised the dominant seed plants to the exclusion of conifers magnoliid dicots and monocots were the dominant taxa and comprised diverse genera and families evidence from palynology and types of preserved cuticle indicates that ferns were subordinate to seed plants in biomass in raton coals in contrast to some described assemblages from the northern western interior paleocene coals from the raton basin show the loss of many cretaceous angiosperm taxa as well as the appearance of new taxa including conifers belonging to taxodiaceae however these taxodiaceae were evergreen and subordinate in abundance to angiosperms vegetational patterns shown by cretaceous paleocene coals of the southern western interior contrast with those of more northerly regions and indicate a poleward gradient in the timing of angiosperm dominance in coal swamps