coal petrology of coal seams from the leao butia coalfield lower permian of the parana basin brazil implications for coal facies interpretations abstract in the leao butia coalfield rio grande do sul the coal seams occur in the rio bonito formation guata group tubarao supergroup of the parana basin brazil and are of permian artinskian kungurian age this study is the first detailed investigation on the coal petrographic characterization of the coal bearing sequence in relation to the depositional settings of the precursor mires both in terms of whole seam characterization and in seam variations the study is based on the analyses of nine coal seams i2 ci l4 l3 l2 l1 s3 s2 s1 which were selected from core of borehole d 193 leao butia and represent the entire coal bearing sequence the interpretation of coal facies and depositional environment is based on lithotype maceral and microlithotype analyses using different facies critical petrographic indices which were displayed in coal facies diagrams the seams are characterized by the predominance of dull lithotypes dull banded dull the dullness of the coal is attributed to relatively high mineral matter inertinite and liptinite contents the petrographic composition is dominated by vitrinite 28 70 vol mmf and inertinite 30 vol mmf groups liptinite contents range from 7 to 30 vol mmf and mineral matter from 4 30 vol microlithotypes associations are dominated by vitrite duroclarite carbominerite and inertite it is suggested that the observed vertical variations in petrographic characteristics lithotypes microlithotypes macerals vitrinite reflectance were controlled by groundwater level fluctuations in the ancient mires due to different accommodation peat accumulation rates correlation of the borehole strata with the general sequence stratigraphical setting suggests that the alluvial fan system and the coal bearing mudstone succession are linked to a late transgressive systems tract of sequence 2 based on average compositional values obtained from coal facies diagrams a deposition in a limno telmatic to limnic coal facies is suggested

impacts of recent paraglacial dynamics on plant colonization a case study on midtre lovenbreen foreland spitsbergen 79 n climatic changes since the end of the little ice age have considerably disturbed environmental balances of plant colonization in high latitudes within one century on spitsbergen valley glaciers have retreated up to one kilometre from their original terminus as of 1918 affecting several hundred hectares of two types of landscape processes plant colonization and paraglacial morphogenesis since these processes are limited to the chronological position of the old ice front it is possible to know the rate of plant colonization by both qualitative and quantitative means as well as speculate on the processes involved such as the effects of runoff the present study is limited to the midtre lovenbreen forefield latitude 79 n longitude 12 e where geomorphologic and floristic samples were collected in 2003 on stable deposits in this area the settlement and the evolution of floristic groups have been documented during this time period of colonization the plain areas are reworked by runoff at a kilometric scale and are characterized as similar to their surrounding biogeographic landscapes thus a relationship can be observed between the paraglacial process occurring in the proglacial forelands and surrounding stable surfaces on till deposits these features that occur as spatial discontinuities across the landscape are perceptible through either plant colonization or disturbance to vegetation caused by hydrological processes ultimately however runoff dynamics maintain pioneer vegetation groups which are superimposed on plant colonization that are driven by temporal periods of deglaciation differences in the rates and the nature of plant colonization are biomarkers of paraglacial dynamics

sequence stratigraphy and coal petrography applied to the candiota coal field rio grande do sul brazil a depositional model abstract the sedimentary rocks of the candiota coal field which belong to the rio bonito formation guata group tubarao supergroup in the parana basin eopermian were studied on the basis of sequence stratigraphy six fourth order parasequences designated a the oldest to f and a third order sequence sequence were identified in outcrops drill cores and well logs the rocks were deposited in an incised valley superimposed on the rocks of the itarare group tubarao supergroup up to 23 coal seams have been observed however they do not extend through the entire coal field the gelification and the tissue preservation indexes based on maceral analysis diessel 1986 were used to infer the depositional environments of the coal seams

sequence stratigraphy of a lagoonal estuarine system an example from the lower permian rio bonito formation parana basin brazil abstract detailed stratigraphic analysis of the early permian artinskian kungurian succession of the intracratonic parana basin in southernmost brazil has revealed that the study region previously interpreted as formed by a barrier island system in a shallow wave dominated sea actually originated mainly in a mixed tide and wave influenced estuary setting four main depositional systems have been recognized alluvial fan fluvial dominated delta lagoonal estuary and barrier shoreface the regional correlation of the lithofacies within the different depositional systems has led to a high resolution stratigraphic framework with three third order depositional sequences sequence boundary sb1 marks the base of the permian succession above the crystalline basement sequence boundary sb2 is characterized by fluvial sediments overlying marine shales and sandstones sequence boundary 3 sb3 has a different signature reflecting differential subsidence some areas clearly experienced temporary regression and basinward shift of facies while in others the transgression rapidly reworked the regressive sediments and left only a thin veneer of pebbly sandstone the typical signature of a transgressive surface coinciding with a sequence boundary within depositional sequence 2 the main target of the study because it has economically important coal seams seven parasequences are recognized two forming the lowstand systems tract of the sequence four forming the transgressive systems tract and one parasequence forming the highstand systems tract two parasequence limits are erosional transgressive surfaces as indicated by the occurrence of a substrate controlled ichnofacies glossifungites and a veneer of intraclasts composed of nodules chert shell fragments and muddy rip up clasts the base level variations had a strong tectonic component as indicated by 1 the shift in shoreline configuration from east west to a north south direction after unconformity sb3 formation 2 the transgressive reworking of regressive sediments in the southern part of the study area indicating differential subsidence and consequent differential accommodation available for the sediments and 3 the angularity displayed by the strata adjacent to the sequence boundary sb3

observations on the nature and origin of fusain abstract evidence for a wildfire origin of fusain is examined charcoal produced by natural fires and artificial charring resembles fossil fusain both in physical size and shape and in optical reflectance artificially charred leaves and naturally burnt wood are illustrated using the sem reflectance studies on modern charcoals suggest that much semifusinite may be produced by pyrolysis the ecological implications of a wildfire origin of fusain are discussed and it is concluded that fires have been a feature of terrestrial ecosystems from at least the late devonian

early permian location of western north american terranes based on brachiopod fusulinid and coral biogeography abstract brachiopod rugose coral and fusulinid faunas present in early permian rocks along northern and western margins of north america in both cratonal localities and accreted terranes have been compared statistically allowing refinement in placement of these terranes relative to the north american continental margin at that time statistical tests including conventional and probabilistic indices of similarity as well as multivariate analysis show that the faunas of wrangellia alexander are most similar to those of stikinia and quesnellia and to the yukon canadian rocky mountains part of the continental margin they also show that faunas of the eastern klamath terrane are most similar to those of stikinia quesnellia and the central cordilleran part of the continental margin these results suggest that during the early permian wrangellia alexander was the northernmost of these terranes lying west of the yukon canadian rocky mountains region and the eastern klamath terrane was the southernmost lying west of the central cordillera stikinia and quesnellia were in intermediate positions these relative latitudes are compatible with latitudinal determinations based on paleomagnetic data faunal diversity in the eastern klamath and stikine terranes is similar to that at similar latitudes on the craton whereas diversity in the wrangellia alexander terrane is considerably lower than that of the latitudinally similar yukon canadian rocky mountains area as diversity is in part a function of temperature this may suggest water around the wrangellia alexander terrane was cooler than that along the continental margin therefore we suggest that warm water currents bathed the southern terranes and the southern and central parts of coastal north america whereas cool water currents influenced the northernmost terrane wrangellia alexander revised otsuka similarity coefficients for corals show higher similarities between western north american terranes and the western continental margin than previously published but they still are relatively low this and the overall patterns of similarity and limits on distribution of tethyan corals and fusulinids in the eastern panthalassa suggest that wrangellia alexander stikinia and the eastern klamath terranes were at approximately the same distance estimated at 2000 3000 km from their latitudinally equivalent segments of the north american craton

the application of famm fluorescence alteration of multiple macerals analyses for evaluating rank of parana basin coals brazil abstract combining vitrinite reflectance vr and fluorescence alteration of multiple macerals famm analyses provide insights into the chemical nature of vitrinites i e perhydrous vs orthohydrous vs subhydrous compositions in permian gondwana coals of the parana basin brazil the famm derived equivalent vr eqvr values and relationships with vr can be determined according to calibration curves based largely on permian gondwana coals of eastern australia the analytical results indicate that vitrinites in the parana basin coals studied generally range from orthohydrous to perhydrous with interpreted vr suppression ranging up to 0 2 absolute for the most perhydrous case the eqvr values of the santa catarina coals which range from about 0 85 to 0 95 differ from vr values by about 0 10 0 15 absolute potentially having significant implications on coal utilization the causes of vitrinite reflectance suppression in the parana basin coals are as yet poorly understood but are likely to be related to a combination of factors

petrological and geochemical characterization of candiota coal seams brazil implication for coal facies interpretations and coal rank abstract seven coal seams from cores of the borehole m iv c 101 candiota coalfield located in rio grande do sul state southern part of the parana basin were analyzed by coal petrographical and organic geochemical methods the seams occur in the rio bonito formation guata group tubarao supergroup of the parana basin and are of permian artinskian kungurian age the composition rank coal facies and depositional environment characterization were made based on lithotype maceral and microlithotype analyses the data were then used in the definition of different types of facies critical petrographical indices and were displayed in diagrams of coal facies in addition coal seams samples from candiota mine were analyzed by proximate total moisture and gross calorific values and were classified using the united nations economic commission for europe un ece classification in addition rock eval pyrolysis liquid chromatography gc and gc ms analyses were made to obtain independent parameters on coal rank and organic matter composition and environment of deposition the results suggest deposition in open mires with elevated contents of detrital macerals and clay minerals and also limno telmatic coal facies coal bearing sequence of coal seams represent a back barrier setting according to the international classification un ece candiota coals are in the subbituminous or low rank coal a stage results from geochemical analyses showed that terrestrial organic matter is predominant as indicated by hydrogen and oxygen indices carbon preference indices and the sterane distribution geochemical maturity parameters such as the 20 s 20 s 20 r and ratios for c 29 regular steranes support the low level of rank maturity as indicated by the vitrinite reflectance measurements 0 41 0 45 and gross calorific values

sequence stratigraphy of paralic coal bearing strata an overview abstract sequence stratigraphy arose in the late 1980s to fundamentally change the science of stratigraphy former practice of labeling formations and erecting stratigraphic columns gave place to a dynamic genetic stratigraphic analysis where the main concern is about understanding the history of sedimentation and to establish models able to predict facies born and mainly applied to an environment of petroleum prospecting and exploration sequence stratigraphy has gained entrance to other branches of sedimentary geology the present paper gives a short introduction to sequence stratigraphic concepts and shows an overview of its application on coal bearing strata two case studies one from the early permian coals of the parana basin brazil and one from the lower cretaceous coals of the western canada sedimentary basin illustrate the concepts

petrology and chemistry of permian coals from the parana basin 1 santa terezinha leao butia and candiota coalfields rio grande do sul brazil the current paper presents results on petrological and geochemical coal seam characterization in permian coal bearing strata from the parana basin southern brazil sequence stratigraphic analysis shows that peat accumulation in permian time was closely linked to transgressive regressive cycles with peat accumulation occurring in a predominantly back barrier lagoonal setting coal petrographic analysis indicates subbituminous coals at candiota and leao butia and high volatile bituminous coals at santa terezinha where locally the coal seams are thermally altered by volcanic intrusions petrographic composition is highly variable with seams at candiota and santa terezinha frequently enriched in inertinite chemical analyses indicate that all coals are mineral matter rich mean 49 09 wt with sio2 and al2o3 dominating as determined by icp aes quartz is also the predominant mineral detected by x ray diffraction where it is associated with feldspar kaolinite and hematite and iron rich carbonates the results from scanning electron microscopy are broadly consistent with the bulk chemical and mineralogical analysis quartz and clays are common in all samples analyzed other minerals observed were amongst others carbonates calcite siderite ankerite pyrite monazite kaolinite barite sphalerite rutile and quartz of volcanic origin the distribution of trace elements is well within the range typical for coal basins of other areas despite the fact that the parana basin coals are very high in ash yields the average concentrations for elements of environmental concern as b be cd co cr cu hg li mn mo ni pb sb se tl u v zn are similar to or less than the mean values for u s coal however considered on an equal energy basis parana basin coals will produce in combustion 5 to 10 times the amount of most elements compared to an equal weight us coal concentrations of major and trace elements such as fe b and s appear to be controlled by depositional setting with increasing values in coal seams overlain by brackish marine strata hierarchical cluster analysis identified three groups of major minerals and seven groups of trace elements based on similarity levels on a regional scale the coalfields can be separated by the differences in rank candiota and leao butia versus santa terezinha and by applying discriminant analysis based on 4 trace elements li as sr sb highest rb and sr values occur at candiota and are linked to syngenetic volcanism of the area whereas high y and sr values at santa terezinha can be related to the frequent diabase intrusions in that area

island arc carbonates characterization and recognition in the ancient geologic record abstract carbonates of island arc origin that are preserved in paleozoic mesozoic terranes of the north american cordillera exhibit a distinctive suite of paleontologic and lithologic features and share a fundamental similarity with limestones forming in modern volcanic arcs this study provides the first detailed synthesis of carbonate depositional systems in island arcs and documents primary sedimentary constituents based on facies relationships and faunal communities models are developed that show patterns in the long term evolution of shallow marine organisms and the construction evolution and demise of carbonate platforms in island arcs a suite of criteria is identified that may be used to differentiate island arc carbonates from limestones that accumulated in other platform settings biogeographic isolation prolonged subsidence steep submarine slopes and tectonic instability of volcanic edifices contribute to the development of relatively high levels of species endemism impoverished normal marine faunas complex provincial affinities and relict biotas in limestones that are characterized by exceptionally thick platform and periplatform sequences fringing and barrier reefs at the shelf margin extensive lagoonal deposits and rapid lateral and vertical facies changes although destructive tectonic and geologic processes in island arcs may hinder determining the original size and extent of the carbonate platform and particular facies types may not be represented e g fringing and barrier reefs may be replaced by sand shoals at the platform margin many characteristics have potential value for identifying carbonates of island arc origin in the ancient rock record apart from being associated with calc alkaline volcanic and volcaniclastic assemblages the most valuable suite of features for recognizing island arc carbonates is marine biotas that exhibit elevated levels of endemism and mixed paleobiogeographic affinities extraordinary thicknesses of platform shallow marine and periplatform carbonates and rapid facies changes between volcanic and carbonate rocks and between shallow and deep water limestones recognizing that an ensemble of features is distinctive within island arc carbonates considerably enhances identification of volcanic arcs in the ancient geologic record and thus improves the likelihood of successfully unraveling the complex geologic history of ocean basins

remnants of the northern sierra nevada paleozoic island arc in western nevada allochthonous upper paleozoic volcanic island arc suites of the u s cordillera have previously been interpreted as parts of a single island arc new lithologic age structural biogeographic and geochemical data indicate the presence at least of two arcs one built on a basement with continental crustal affinities including that of the northern sierra terrane and the other built on an oceanic basement including that of the eastern klamath terrane in the garfield hills western nevada the lower permian black dike formation appears to be a remnant of the northern sierra paleozoic island arc it consists of calc alkaline rocks with low to negative epsilon nd ratios volcanic rocks share similar ages magmatic affinities and epsilon nd ratios with lavas of the goodhue formation in the northern sierra terrane our new data suggest that these rocks are part of the northern sierra terrane and we therefore infer that part of western nevada was originally underlain by a basement with continen

far travelled permian chert of the north fork terrane klamath mountains california permian chert in the north fork terrane and correlative rocks of the klamath mountains province has a remanent magnetization that is prefolding and presumably primary paleomagnetic results indicate that the chert formed at a paleolatitude of 8 6 2 5 but in which hemisphere remains uncertain this finding requires that these rocks have undergone at least 8 6 4 4 of northward transport relative to permian north america since their deposition paleontological evidence suggests that the permian limestone of the eastern klamath terrane originated thousands of kilometers distant from north america the limestone of the north fork terrane may have formed at a similar or even greater distance as suggested by its faunal affinity to the eastern klamath terrane and more westerly position available evidence indicates that convergence of the north fork and composite central metamorphic eastern klamath terranes occurred during triassic or early jurassic time and that their joining together was a middle jurassic event primary and secondary magnetizations indicate that the new composite terrane containing these and other rocks of the western paleozoic and triassic belt behaved as a single rigid block that has been latitudinally concordant with the north american craton since middle jurassic time

mesozoic tectonic evolution of the proto south china sea a perspective from radiolarian paleobiogeography abstract the proto south china sea pscs represents the lithosphere that formerly occupied the region southeast of south china where the present day south china sea is located the subduction and demise of the pscs have attracted wide attention whereas the pre subduction history particular the mesozoic of the region remains relatively neglected in this paper the radiolarian paleobiogeography of the region is analyzed to identify the paleobiogeographic affinity and paleo connectivity of the pscs with the pacific and tethys oceans during the mesozoic then the continent ocean configuration and tectonic evolution of the pscs and adjacent areas are discussed through the integration of paleobiogeographical results and associated paleomagnetic stratigraphic and petrologic data the main conclusions are as follows 1 during the triassic the pscs was situated in the transition zone between the pacific and tethys oceans and its paleobiogeography was influenced by both oceans the pscs was characterized by complex tectonic overprinting by the pacific and tethyan tectonic regimes 2 in the early middle jurassic the pscs was well connected to the pacific ocean but poorly connected to the tethys ocean consistent with the paleobiogeography of the pscs being mainly constrained by the pacific ocean the pscs was part of the paleo pacific slab 3 during the late jurassic cretaceous the pscs was in a semi closed environment the late jurassic early late cretaceous pscs was part of a west facing andean type subduction zone and the late late cretaceous pscs was situated in an extensional tectonic setting

the early triassic ammonoid recovery paleoclimatic significance of diversity gradients ammonoids recovered much faster than other marine shelly invertebrates after the end permian mass extinction based on a refined global data set at the basin level we investigate the paleobiogeographical global latitudinal and longitudinal diversity patterns in terms of climatic changes during the early triassic such analysis differs from already published qualitative or quantitative studies in that it estimates faunal patterns and endemicity at an ecologically meaningful level of spatial resolution i e at the basin level during the early triassic the global first order trend in increasing ammonoid diversity was accompanied by a progressive change from cosmopolitan to latitudinally restricted distributions this led to the emergence of a clear latitudinal diversity gradient during most of the smithian and spathian stages which entails increased steepness of the sea surface temperature gradient during the late early triassic however two brief episodes of ammonoid cosmopolitanism combined with low global diversity interrupted the first order increasing trend at the very beginning of the smithian and at its very end the longitudinal analysis of smithian distributions indicates a westward decrease of diversity within the tethys which faded away during the spathian analysis of endemicity indicates a rapid biogeographical maturing and structuring of faunas concomitant with the edification of the latitudinal diversity gradient

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

a new u pb zircon age dating and palynological data from a lower permian section of the southernmost parana basin brazil biochronostratigraphical and geochronological implications for gondwanan correlations abstract index species useful for correlations with the international stratigraphical column are rare or absent in the pennsylvanian permian strata of the parana basin in brazil preventing accuracy in geochronologic assignments besides absolute datings are very scarce in comparison with other gondwana basins this paper presents palynological data from an outcrop on the surroundings of the candiota coal mine southmost brazil from several levels of the rio bonito and palermo formations the presence of certain index species of spore pollen allowed the recognition of two permian palynozones the vittatina costabilis and the lueckisporites virkkiae zones furthermore u pb in zircons from a volcaniclastic level interbedded in the coal strata of the former unit was analyzed through la mc icp ms method providing a new absolute age dating of 281 4 3 4 ma cisuralian early permian this dating is assumed as the oldest occurrence of the l virkkiae zone in parana basin which contains index species that are widespread in other gondwana basins a well distributed surface boundary occurs in this section also allowing local and regional correlations these new biostratigraphical and geochronological data are integrated in order to offer a deep analysis on the stratigraphical significance for correlations across the occidental gondwana

smithian and spathian early triassic ammonoid assemblages from terranes paleoceanographic and paleogeographic implications early triassic paleobiogeography is characterised by the stable supercontinental assembly of pangea however at that time several terranes such as the south kitakami massif sk south primorye sp and chulitna respectively and presently located in japan eastern russia and alaska straddled the vast oceans surrounding pangea by means of quantitative biogeographical methods including cluster analysis non metric multidimensional scaling and bootstrapped spanning network applied to smithian and spathian early triassic ammonoid assemblages we analyze similarity relationships between faunas and suggest paleopositions for the above cited terranes taxonomic similarities between faunas indicate that primary drivers of the ammonoid distribution were sea surface temperature and currents possible connections due to current controlled faunal exchanges between both sides of the panthalassa are shown and terranes such as sk sp and chulitna played an important role as stepping stones in the dispersal of ammonoids sk and sp terranes show strong sub equatorial affinities during the smithian thus suggesting a location close to south china at the same time the chulitna terrane shows strong affinities with equatorial faunas of the eastern panthalassa this paleoceanographic pattern was markedly altered during the spathian possibly indicating significant modifications of oceanic circulation at that time as illustrated by the development of a marked intertropical faunal belt across tethys and panthalassa

the burning of gondwana permian fires on the southern continent a palaeobotanical approach abstract fossil charcoal has widely been accepted as a direct indicator for the occurrence of palaeo wildfires in upper palaeozoic sediments of euramerica and cathaysia records of these remains are relatively common and regionally and stratigraphically more or less homogeneously distributed in terrestrial sequences on the other hand just a few records have been published for the permian of gondwana and only recently has it been demonstrated that macroscopic charcoals are also common here most permian macroscopic charcoal from gondwana is gymnospermous and has been reported from coal bearing strata macroscopic charcoal occurrences are spread out in different sequences and also in distinct stratigraphic intervals in the permian e g parana basin sakmarian artinskian of brazil karoo basin artinskian of south africa damodar basin lopingian of india and dead sea area changhsingian of jordan they range from peri glacial post glacial to warm temperate climatic systems throughout the permian macro and micro charcoal occurrences are compared to inertinite incidences to support the pyrogenic origin for these coal macerals and to provide an up to date overview on the known evidences of permian wildfires on gondwana in space and time

concordant paleolatitudes for neoproterozoic ophiolitic rocks of the trinity complex klamath mountains california 1 new paleomagnetic results from the eastern klamath mountains of northern california show that neoproterozoic rocks of the trinity ophiolitic complex and overlying middle devonian volcanic rocks are latitudinally concordant with cratonal north america combining paleomagnetic data with regional geologic and faunal evidence suggests that the trinity complex and related terranes of the eastern klamath plate were linked in some fashion to the north american craton throughout that time but that distance between them may have varied considerably a possible model that is consistent with our paleomagnetic results and the geologic evidence is that the trinity complex formed and migrated parallel to paleolatitude in the basin between laurasia and australia east antarctica as the rodinian supercontinent began to break up it then continued to move parallel to paleolatitude at least through middle devonian time although the eastern klamath plate served as a nucleus against which more western components of the klamath mountains province amalgamated the klamath superterrane was not accreted to north america until early cretaceous time index terms 1525 geomagnetism and paleomagnetism paleomagnetism applied to tectonics regional global 5475 planetology solid surface planets tectonics 8149 8157 tectonophysics evolution of the earth plate motions past 3040 9350 information related to geographic region north america 9619 information related to geologic time precambrian

nina creek group and lay range assemblage north central british columbia remnants of late paleozoic oceanic and arc terranes in north central british columbia a belt of upper paleozoic volcanic and sedimentary rocks lies between mesozoic arc rocks of quesnellia and ancestral north america these rocks belong to two distinct terranes the nina creek group of the slide mountain terrane and the lay range assemblage of the quesnel terrane the nina creek group is composed of mississippian to late permian argillite chert and mid ocean ridge tholeiitic basalt formed in an ocean floor setting the sedimentary and volcanic rocks the mount howell and pillow ridge successions respectively form discrete generally coeval sequences interpreted as facies equivalents that have been interleaved by thrusting the entire assemblage has been faulted against the cassiar terrane of the north american miogeocline west of the nina creek group is the lay range assemblage correlated with the harper ranch subterrane of quesnellia it includes a lower division of mississippian to early pennsylvanian sedimentary and volcanic rocks some with con

the eo permian coal seams of the parana basin in southernmost brazil an analysis of the depositional conditions using sequence stratigraphy concepts the eo permian of the parana basin is studied using sequence stratigraphy the study was based on data acquired from 92 entirely cored and geophysically logged boreholes the study is an applicability test of the conceptual and methodological framework of sequence stratigraphy in the examination of the coal seams of the eo permian rio bonito formation the coal seams were predominantly deposited in a lagoon barrier system linked with a third order transgressive systems tract subdivided into four parasequence sets each set represents a major transgressive pulse in the sedimentary history of the basin

permian longitudes of wrangellia stikinia and eastern klamath terranes based on coral biogeography trend surface analysis of biogeographic data and probabilistic estimates of diversity and similarity provide a new approach to understanding the origin of north american suspect terranes results from permian corals indicate that 1 the eastern boundary of the tethyan coral province was about 2000 km west of the north american craton 2 eastern klamath and stikinia were close to one another and were up to 6700 km west of north america during the early permian 3 wrangellia was situated to the southeast of stikinia as much as 5000 km west of the craton 4 the late permian location of the eastern klamath terrane was 3000 5800 km west of the craton and between 11 and 21 n and 5 the eastern klamath terrane moved westward during the permian possibly as a result of back arc spreading

3d stratigraphic forward modeling of an ancient transgressive barrier system a case study of accuracy and sensitivity abstract accuracy of geological modeling and understanding of the controlling parameters in sedimentary systems evolution are challenges in both academy and industry uncertainty in the prediction of spatial and temporal facies distributions and difficulties in quantitative analysis of controlling parameters are current challenges to increase geological model certainty and sedimentary process understanding computational modeling has evolved exponentially during the last 50 years in this study 3d stratigraphic forward modeling technique is used to simulate an ancient transgressive barrier system of southern brazil deposited during the lower permian in the parana basin upper part of the rio bonito formation in the study area the depositional systems are part of a large transgressive cycle that includes fluvial estuarine facies at the base and barrier lagoon deposits associated with the development of salt marshes at the top throughout the region offshore strata cover the barrier lagoon facies the simulation successfully represented the retrograde evolution of the coastal barrier system with longshore currents as the main transport mechanism of sediments the evolution of the barrier system started with upper shoreface deposits overlying the lagoon system facies in the south later lower shoreface sediments covered upper shoreface deposits then shoreline migration continued landward finally offshore transition deposits covered all previous deposits simulations and tests of controlling parameters allowed an adjustment to actual thickness and lithologies up to 83 these simulations allowed for the analysis of model sensitivity in particular to the influence of parameters that control sedimentary evolution the main controlling parameter was sediment supply volume and composition followed by time step initial bathymetry and sediment velocity had less of an impact

u pb dating of tonstein layers from a coal succession of the southern parana basin brazil a new geochronological approach abstract this paper presents new radiometric dating of zircons idtims u pb from tonsteins interbedded with coal seams from the candiota coalfield rio grande do sul state the ages obtained 296 9 1 65 ma and 296 4 2 ma are consistent within error and are quite different from a previously published age of 267 1 3 4 ma calibrations of palynostratigraphic data with numerical ages showed that the candiota coals from the southern parana basin related to the protohaploxypinus goraiensis subzone are constrained to the asselian consequently the basal part of the gondwana sequence in the southern part of the basin must belong to the carboniferous permian boundary and not to the sakmarian as it was previously considered the new results have far reaching significance for correlations of the parana basin with sequences of the argentinian paganzo basin 302 6 ma and 288 7 ma and also with the karoo basin with the top of the dwyka tillite 302 3 ma and 299 2 3 2 ma and with the lowermost ecca group 288 3 ma and 289 6 3 8 ma this new evidence supports the presence of an active and widespread upper carboniferous volcanism in western gondwana

paleoecology biogeography and evolution of reef ecosystems in the panthalassa ocean during the late triassic insights from reef limestone of the sambosan accretionary complex shikoku japan upper triassic reefs from the panthalassa ocean have been understudied in comparison to their tethyan counterparts and are therefore pivotal to understanding the global reef evolution during the late triassic to fill this gap upper triassic reef limestone from ten localities of the sambosan accretionary complex at shikoku island japan has been investigated biotic assemblages quantitative microfacies analysis and integrated biostratigraphy allow us to characterize two types of reefs those attributed to the ladinian early carnian and those attributed to the late carnian rhaetian at the regional scale our data refine the biostratigraphic framework of the upper triassic sambosan limestone at the global scale multivariate analyses support a strong paleobiogeographic affinity of the western panthalassa reef biota with those of the south tethys ocean during the ladinian carnian and norian rhaetian additionally they indicate connections with east panthalassa reefs during the norian rhaetian

absolute dating of permian ash fall in the rio bonito formation parana basin brazil abstract the rio bonito formation in southern parana basin contains a set of tonsteins interbedded with coal seams these tonsteins are composed mainly of kaolinite with zircon apatite and beta quartz paramorphs as accessory minerals and were interpreted as volcanic ashes deposited by ash falls over pits protected by barrier islands in a barrier lagoon system a u pb dating of zircons in the tonstein a which furnished an age of 267 1 3 4 ma early permian confirming previous age dates based on palynology and correlating them with one of the main periods of volcanic activity in the gondwana the source of the pyroclastic material was attributed to the early permian choiyoi magmatic arc in argentina developed during the sanrafaelic orogeny and with a main peak of volcanic activity between 260 and 272 ma

permian carbonaceous rocks from the bonito coalfield santa catarina brazil organic facies approaches abstract permian sedimentary rocks of the rio bonito formation parana basin in the santa catarina state brazil contain three important coal seams in a descending order barro branco bonito superior and pre bonito superior artinskian carbonaceous shale samples corresponding to the so called bonito coal were sampled at the mine face of the coal bed of the bonito i underground mine these samples were analyzed in order to discuss their petrographical geochemical palynological and paleobotanical characteristics palynological analyses demonstrated abundant and well preserved palynomorphs showing a dominance of bisaccate pollen grains related to gymnospermic plants wood fragments preserved as coalified compression show the presence of lycophyta palynofacies on samples demonstrated good results for the recognition of preserved organic matter and changes in paleoenvironmental conditions along the sedimentary sequence palynofacies and palynological analyses indicate changes in paleoecological conditions that have favored the development of different plant communities during the depositional time span from a forested gymnosperm at the base to a lycophyte arborescent plant dominated scenario at the top suggesting a shift to coastal environment the microscopic maceral group analyses reveal a predominance of liptinite and vitrinite over inertinite while among microlithotypes carbargilite is abundant the joint occurrence of inertinite as a maceral in the carbonaceous rock and charcoal in associated shales suggests that the mire and near surroundings were regularly subject to wildfires mean random vitrinite reflectance rr varies from 0 88 to 1 04 the liptinite spectral fluorescence parameters obtained for samples show the max values varying from 610 to 650 indicating equivalent vitrinite reflectance rreq values from 0 83 to 1 10 these results show that the equivalent vitrinite reflectance rreq correlates well with the measured vitrinite reflectance rr the bonito coal is a high volatile bituminous coal according to the iso 11760 2005 standard total organic carbon varies from 2 4 to 44 0 wt and sulfur is present in moderate to high contents gc ms analyses evidenced a predominance of even saturated hydrocarbons and the presence of hopanes and steranes