basin development and syntectonic sedimentation associated with kinematically coupled strike slip and detachment faulting southern nevada a previously unrecognized 12 10 ma clastic sequence is distributed widely south of the las vegas valley shear zone and north of lake mead in southern nevada structural and stratigraphic evidence from these sedimentary and associated volcanic rocks suggests that basin development was kinematically related to movement along the las vegas valley shear zone major movement along the nearby saddle island detachment also occurred within this time interval we suggest that spatially and temporally related basin development sedimentation and stratal tilting reflect kinematically coupled movement along a combined las vegas valley shear zone saddle island detachment fault system

the lilliput effect in the aftermath of the end permian extinction event early triassic animal body fossils and trace fossils are small relative to those in older and younger intervals size decreases sharply through the end permian extinction event and permian triassic boundary and the smallest sizes are encountered in the parvus and isarcica zones of the earliest induan animals appearing within these two zones are also exceedingly small compared to younger congenerics and conspecifics temporary dramatic size decrease of surviving taxa in the immediate aftermath of the extinction event is an example of the lilliput effect coined by urbanek a 1993 biotic crises in the history of upper silurian graptoloids a palaeobiological model historical biology 7 29 50 body size increases somewhat from the carinata zone mid induan but remains depressed for the duration of the early triassic and pre extinction sizes are not commonly recorded until at least the middle triassic marine and terrestrial faunas appear to be similarly affected the lilliput effect and longer term size reduction could be the result of several factors environmental parameters such as marine anoxia due to low atmospheric concentrations of oxygen at this time coupled with sluggish ocean circulation in a greenhouse world and food shortage are the likely proximal causes for the early triassic lilliput effect no single cause can explain all the observations and a combination of factors are likely to be involved

cretaceous tertiary and permian triassic boundary events compared abstract the cretaceous tertiary k t and permian triassic p tr events differ in many more aspects than they are similar this alone makes it unlikely that they are parts of a common web of periodic mass extinction events mee unlike the k t most mee have no ir anomalies and where in the comparatively complete section of the p tr at gartnerkofel austria weak ir concentrations are found their ratios to siderophile elements co ni cr are far less than chondritic in contrast ratios to chalcophile elements as sb zn never approach chondritic even in k t peaks and locality differences suggest local depositional processes that may also affect the siderophiles profiles of isotopes 13ccarb 87 sr 86 sr and possibly 18ocarb across these boundaries also differ radically whereas the k t profile of surface ocean 18ocarb has been shown to be mainly a drop in primary productivity the p tr profile is interpreted at least in part to be a consequence of a large and accelerating oxidation of previously stored corg with greatly differing consequences for climate these and other differences of proximate forcings for these two mee lead us to a hypothesis that such external exigencies were ever intermittently and severally with us but were effective only when the biotic web had already internally unravelled in some crucially strained patch gaia became antigaia

timing of recovery from the end permian extinction geochronologic and biostratigraphic constraints from south china four volcanic ash beds bracket the early middle triassic boundary as defined by conodont biostratigraphy in a stratigraphic section in south china high precision u pb dates of single zircons allow us to place the early to middle triassic olenekian anisian boundary at 247 2 ma magnetic reversal stratigraphy allows global correlation the new dates constrain the early triassic interval characterized by delayed biotic recovery and carbon cycle instability to 5 m y this time constraint must be considered in any model for the end permian extinction and subsequent recovery

rock types and permeability prediction from dipmeter and image logs shuaiba reservoir aptian abu dhabi the shuaiba formation is a complex carbonate reservoir characterized by small scale geological heterogeneity primarily related to rudist macrofauna the textural heterogeneity corresponds to extreme permeability variation that is the controlling factor in reservoir production because of the large vertical resolution contrast between cores actual scale and conventional logs averaged responses over a few feet extrapolation of small scale heterogeneity into uncored wells using a traditional approach is unreliable high resolution log data like dipmeters and image logs are required to characterize small scale heterogeneity that is essential to a good three dimensional 3 d geological model that predicts true reservoir behavior our study illustrates an approach to improve the reservoir characterization of the shuaiba by quantifying small scale heterogeneity using dipmeter and image logs a methodology is proposed to use the existing high resolution high resolution dipmeter tool hdt stratigraphic high resolution dipmeter tool shdt and formation microscanner fms and conventional log data to characterize and extrapolate geological heterogeneity texture and neural network analyses derived from microresistivity variations and a multiregression approach have been used in two wells to demonstrate the methodology both rock types and permeability are estimated for extrapolation into uncored wells although differences between the conductivity of conductive and resistive areas when normalized for background conductivity are an indirect measure of permeability for hdt and shdt the connectivity coefficient of conductive anomalies derived from textural analysis is related to permeability in the case of fms reservoir rock types rrt obtained from the methodology correlate well with rrts derived from the integration of core special core analysis scal and conventional log data in two test wells permeability estimations including small scale extreme variations from less than 1 md in tight mudstones to greater than 1 d in caprinid rudstones are in good agreement with the core plug permeability measurements after a simple calibration in one example permeability trends in rudist rrts which are not discernible using core plugs and minipermeameter data are clearly resolved using shdt data the degree of correlation between estimated and core permeabilities is greater with increased vertical resolution of the tool hdt lowest fms highest distinct rrts resulting from small scale geological heterogeneity can be classified and permeability can be estimated with a high degree of confidence providing a better pathway of extrapolating from core data to conventional logs for 3 d modeling the methodology has potential application to other carbonate and siliciclastic reservoirs with appropriate calibration and scaling underused hdt shdt fms and fullbore formation microimager fmi databases are available in many other areas that could be analyzed an order of magnitude improvement in the ability to characterize small scale heterogeneity has significant implications for future coring logging programs and reservoir characterization efforts duffy russell is a senior carbonate geologist at saudi aramco in the reservoir characterization department southern fields characterization division he received b s and m s degrees in geology from north carolina state university in 1976 and duke university in 1979 and a ph d in geology from the university of aberdeen in 2001 he started his career as a geophysicist with amoco production company in 1979 and has worked nearly 21 years as a geologist for mobil oil corporation and exxonmobil specializing in carbonate reservoir characterization mahmoud akbar is a principal geologist for schlumberger working iran qatar the united arab emirates oman and yemen he started his professional career with schlumberger wireline and testing in 1985 in pakistan he received b sc 1983 and m sc 1985 degrees in applied geology from the university of punjab pakistan he has carried out research in the lower himalayas on factors controlling fractures and their effect on rock strength badarinadh vissapragada is a senior petrophysicist with schlumberger data and consulting services abu dhabi united arab emirates he did his postgraduate study in geophysics at andhra university waltair india he has more than 19 years of petrophysics experience in india and middle east reservoirs from fieldwide petrophysical studies and reservoir characterization his special interests are reservoir rock typing permeability and fracture detection gordon walkden is head of the department of geology and petroleum geology at the university of aberdeen scotland after receiving a degree from quintin school in london he obtained his ph d in carbonate sedimentology from manchester university united kingdom in 1970 gordon was appointed senior lecturer in 1988 and became department head in 1993 he has extensive field experience and supervision of research projects in britain europe north america and the middle east

the permo triassic extinction the end permian mass extinction brought the palaeozoic great experiment in marine life to a close during an interval of intense climatic tectonic and geochemical change improved knowledge of latest permian faunas coupled with recent advances in isotopic studies and biostratigraphy have greatly enhanced our understanding of the events of 250 million years ago and have begun to provide answers to many questions about the causes of extinction

the age of the permian triassic boundary abstract the 5 cm boundary clay bed in the chinese stratotype section through the permian triassic boundary has been recognised as a bentonite shrimp ion microprobe dating of zircons in the bentonite indicates a magmatic age of 251 2 3 4 ma 2 this is the first direct constraint on the numerical age of the permian triassic boundary future refinements of ages at this important but poorly constrained level of the phanerozoic timescale may depend on re analysis of this uniquely placed volcanic horizon and other bentonites in the fossiliferous chinese upper permian and lower triassic the utility of defining the permian triassic boundary in the chinese stratotype section in the vicinity of known dateable horizons should be considered

a geographical information system gis study of triassic vertebrate biochronology geographical information systems gis have been applied extensively to analyse spatial data relating to varied environmental issues but have not so far been used to address biostratigraphical or macroevolutionary questions over extended spatial and temporal scales here we use gis techniques to test the stability validity and utility of proposed middle and late triassic land vertebrate faunachrons lvfs a global biostratigraphical framework based upon terrestrial freshwater tetrapod occurrences a database of tetrapod and megafloral localities was constructed for north america and western europe that also incorporated information on relevant palaeoenvironmental variables this database was subjected to various spatial analysis techniques our gis analysis found support at a global level for eocyclotosaurus as an anisian index taxon and probably aetosaurus as a norian indicator other tetrapod taxa are useful biostratigraphical biochronological markers on a regional basis such as longosuchus and doswellia for late carnian time other potential index fossils are hampered however by taxonomic instability mastodonsaurus metoposaurus typothorax paleorhinus pseudopalatus redondasaurus redondasuchus and or are not clearly restricted in temporal distribution paleorhinus angistorhinus stagonolepis metoposaurus and rutiodon this leads to instability in lvf diagnosis we found only in the western northern hemisphere is there some evidence for an anisian ladinian biochronological unit amalgamating the perovkan and berdyankian lvfs and a possible late carnian unit integrating the otischalkian and adamanian megaplants are generally not useful for biostratigraphical correlation in the middle and upper triassic of the study area but there is some evidence for a carnian age floral assemblage that corresponds to the combined otischalkian and adamanian lvfs environmental biases do not appear to strongly affect the spatial distribution of either the tetrapods or megaplants that have been proposed as index taxa in biostratigraphical schemes though several examples of apparent environmental bias were detected by the analysis consequently we argue that further revision and refinement of middle and late triassic lvfs is needed before they can be used to support global or multi regional biostratigraphical correlations caution should therefore be exercised when using the current scheme as a platform for macroevolutionary or palaeoecological hypotheses finally this study demonstrates the potential of gis as a powerful tool for tackling palaeontological questions over extended timescales

global climate perturbations during the permo triassic mass extinctions recorded by continental tetrapods from south africa several studies of the marine sedimentary record have documented the evolution of global climate during the permo triassic mass extinction by contrast the continental records have been less exploited due to the scarcity of continuous sections from the latest permian into the early triassic the south african karoo basin exposes one of the most continuous geological successions of this time interval thus offering the possibility to reconstruct climate variations in southern laurasia from the middle permian to middle triassic interval both air temperature and humidity variations were estimated using stable oxygen 18op and carbon 13cc isotope compositions of vertebrate apatite significant fluctuations in both 18op and 13cc values mimic those of marine records and suggest that stable isotope compositions recorded in vertebrate apatite reflect global climate evolution in terms of air temperature oxygen isotopes show an abrupt increase of about 8 c toward the end of the wuchiapingian this occurred during a slight cooling trend from the capitanian to the permo triassic boundary ptb at the end of the permian an intense and fast warming of 16 c occurred and kept increasing during the olenekian these thermal fluctuations may be related to the emeishan south china and siberian volcanic paroxysms that took place at the end of the capitanian and at the end of the permian respectively vertebrate apatite 13cc partly reflects the important fluctuations of the atmospheric 13c values the differences with marine curves being likely due to the evolution of local humidity both the oxygen and carbon isotope compositions indicate that the ptb was followed by a warm and arid phase that lasted 6 ma before temperatures decreased during the late anisian toward that of the end permian environmental fluctuations occurring around the ptb that affected both continental and marine realms with similar magnitude likely originated from volcanism and methane release

vertebrate diversity across the end permian mass extinction separating biological and geological signals abstract this study examines regional diversity patterns of permian triassic terrestrial vertebrates of the south african karoo basin and the russian fore ural region previous studies clearly established that the diversity patterns of synapsids the dominant terrestrial tetrapods of their time are significantly biased by heterogeneity in the permian triassic terrestrial rock record this conclusion was based on a positive correlation between taxonomic diversity estimates tdes and varying sampling proxies 1 number of formations and 2 outcrop area recently these proxies have been criticized to be non independent variables or problematic for other reasons and 3 number of localities or 4 number of specimens have been suggest as more reliable proxies in the present study i test the relevance of the latter proxies 2 4 with respect to vertebrate diversity in south africa and russia on these regional scales log transformed and generalized differenced tdes of vertebrates at varying taxonomic levels are with few exceptions not significantly correlated with the various sampling proxies 2 4 for the complete time series after eliminating the impact of the end permian extinction event by excluding the earliest triassic time intervals selected vertebrate tdes in south africa and russia show statistically significant strong positive correlations with outcrop area number of localities and number of specimens diversity residuals resulting from modeled diversity estimates exhibit clade specific patterns with little support for a mid permian end guadalupian event but strong support for a severe end permian extinction the results imply that although vertebrate diversity patterns in south africa and russia are at least partially biased by the permian triassic terrestrial rock record they still preserve genuine biological signals finally it is important to note that outcrop area represents a valid and useful sampling proxy at the regional scale of the south african karoo basin and that it should be used in concert with other sampling proxies such as the number of localities and specimens that accurately capture various aspects of sampling in a given study area as it has been performed in the present study

a review on the applications of image logs in structural analysis and sedimentary characterization abstract image logs provide important information on lithology sedimentary textures paleoflow directions fractures and in situ stress analysis lacking of criteria used for establishing the image log facies limits the applications of image logs in sedimentary reservoir interpretation this paper provides a thoroughgoing review focusing on the recent applications of borehole image logs for sedimentological and structural description and interpretation and aims to establish image log facies which can provide guidelines in sedimentary reservoir interpretation this paper firstly summarizes the principles and basic characteristics of various imaging logging tools and then briefly introduces the pre processing workflow of the image log data then the generated images are used for depth and orientation shifts of cores by calibrating individual sedimentary and structural features descriptive and concise image log facies are established based on combinations of image textures including dip type dip pattern and color scheme and the characteristics as well as physical criteria for each individual image facies are summarized the established image log facies are then interpreted in terms of structural and sedimentological features such as lithology sedimentary structures vugs fractures and faults the image log facies and its stacking patterns are then used to interpret the lithofacies associations by calibrating with cores and conventional logs natural fractures and induced fractures are recognized by image logs and the principles of breakouts and drilling induced fractures for in situ stress analysis are reviewed then the applications of image logs in investigation of fracture attitudes and states as well as in computation of fracture parameters are summarized the procedures to evaluate fracture effectiveness through image logs are discussed at last the application of image logs for structural dip analysis is reviewed and image logs are used for recognizing faults fracture sets and attitudes of stratum through the dip patterns the basic procedures for paleocurrent reconstruction which includes dip picking of cross beddings structural dip determination and structural dip removal are reviewed then the paleocurrent directions of the lower cretaceous bashijiqike formation in the kuqa depression were reconstructed which could help further understanding of the depositional systems this review will help extend the utility of image logs in interpreting small to large scale sedimentary and structural features and bridges the gaps between well log analysis and sedimentary and structural interpretation

characterization of braided river delta facies in the tarim basin lower cretaceous application of borehole image logs with comparative outcrops and cores abstract borehole electrical image log with core like presentation is an efficient way to conduct sedimentary description in the subsurface the key is to set up a series of geological diagnostic criteria the subsurface lower cretaceous bashijiqike formation in the kelasu belt kuqa depression described as a sedimentary facies of braided river delta front has measured a mass of borehole image logs and open hole logs at depths more than 6000 m combined with comparative outcrops limited cores and thin sections high quality borehole images were fine calibrated to reveal their sedimentary details with the aim of subtle sedimentary interpretation in the uncored intervals the image elements all have corresponding geological indications the lithologies are interpreted including mudstones siltstones fine and medium sandstones and conglomerates and the sedimentary structures are interpreted in terms of various bedding types scoured surface and stacking modes thus interdistributary bay sandy or conglomerate subaqueous distributary channel and channel mouth bar are interpreted based on the lithologies sedimentary structures and textures basal and top contacts and succession variations furthermore determination of paleo current direction using borehole image logs is proposed for some time but is far from mature and need to consider tectonic deformation settings of studied stratigraphy based on this the paleo current in the kelasu belt is interpreted to flow southward from the southern tianshan to the depression during the early cretaceous which is consistent with the results derived from the heavy mineral analysis however the subaqueous distributary channels could frequently migrate locally and the paleo current direction changed at localities with an offset angle varied between 30 and 150 regionally the scale of single sand body decreases lakeward and the sand body may stretch at a maximum distance of 685 1 m along the flow direction the diagnostic criteria and the workflow for borehole image interpretation in this study will have potential application to subsurface sedimentary description and guide sedimentary architecture where cores are not available

improving the upper triassic numerical time scale from cross correlation between tethyan marine sections and the continental newark basin sequence abstract magnetostratigraphic cross correlations between biochronologically well dated tethyan marine sections and the astronomically tuned sedimentary sequence from the continental newark basin eastern north america help to improve the upper triassic time scale we show here that the most recent radiometric results constraining the age of the base and top of the upper triassic 237 and 200 ma respectively strengthen the chronostratigraphic calibration of the newark sedimentary sequence proposed by krystyn et al earth planet sci lett 203 2002 343 351 these results allow one to reconcile the milankovitch based cyclostratigraphy from the newark sequence the magnetostratigraphic data from both marine and continental environments and upper triassic biostratigraphy including data on tethyan marine faunas and on terrestrial vertebrates according to this calibration the successive upper triassic stages would have very different durations 10 myr for the carnian 237 227 ma 25 myr for the norian 227 202 ma and 2 myr for the rhaetian 202 200 ma but only if the entire rhaetian is recorded in the newark sequence we further show that the biozone durations in the upper triassic would have been highly variable and as a whole would have lasted much longer than in the lower and middle triassic

rapid least squares inversion of apparent resistivity pseudosections by a quasi newton method1 a fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer this technique is based on the smoothness constrained least squares method and it produces a two dimensional subsurface model from the apparent resistivity pseudosection in the first iteration a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically for subsequent iterations a quasi newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times respectively compared to the conventional least squares method tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly this technique takes about one minute to invert a single data set on an 80486dx microcomputer

the first occurrence of chanaresuchus bonapartei romer 1971 archosauriformes proterochampsia of the middle triassic of brazil from the santacruzodon assemblage zone santa maria formation parana basin

vegetation history across the permian triassic boundary in pakistan amb section salt range hypotheses about the permian triassic floral turnover range from a catastrophic extinction of terrestrial plant communities to a gradual change in floral composition punctuated by intervals indicating dramatic changes in the plant communities the shallow marine permian triassic succession in the amb valley salt range pakistan yields palynological suites together with well preserved cuticle fragments in a stratigraphically well constrained succession across the permian triassic boundary palynology and cuticle analysis indicate a mixed glossopteris dicroidium flora in the late permian for the first time dicroidium cuticles are documented from age constrained upper permian deposits on the indian subcontinent close to the permian triassic boundary several sporomorph taxa disappear however more than half of these taxa reappear in the overlying smithian to spathian succession the major floral change occurs towards the dienerian from the permian triassic boundary up to the middle dienerian a gradual increase of lycopod spore abundance and a decrease in pteridosperms and conifers are evident synchronously the generic richness of sporomorphs decreases the middle dienerian assemblages resemble the previously described spore spikes observed at the end permian norway and in the middle smithian pakistan and might reflect a similar ecological crisis

delineation of near surface structure in the southern part of 15th of may city cairo egypt using geological geophysical and geotechnical techniques the integration of geological geophysical and geotechnical interpretation at the southern part of 15th of may city have been used to evaluate the subsurface stratigraphy especially the clay layer which may cause serious danger to construction those techniques have been used to delineate the subsurface structures as normal faults which play a critical role on the stability of buildings geological setting of the area has been evaluated through the construction of a geological map from different geological sections and samples obtained from more than 30 observation points geophysical tools such as vertical electrical soundings 12 vess 2 d dipole dipole array 7 sections p wave shallow seismic refraction 31 profiles and multiple channel analysis of surface waves 31 masw profiles have been carried out to image the subsurface situation geotechnical evaluation using 26 boreholes samples laboratory tests and geotechnical parameters has been done at the area of interest the geological setting demonstrates that the city had been constructed on the second and third members of qurn formation upper eocene composed of argillaceous limestone marl and shale two normal faults are passing through the area were observed the resistivity ves and dipole dipole and seismic p waves and masw results reflect the presence of the two normal faults cross the study area affecting the obtained section of marl clayey marl and limestone layers the geotechnical information indicate the presence of the normal faults and the existence of clay layer with swelling ability reaching 140 which may cause cracks in the upper layers and or subsidence

geophysical investigation for shallow subsurface geotechnical problems of mokattam area cairo egypt nine vertical electrical soundings of schlumberger configuration were measured with ab 2 1 500 m manual and computerized interpretation were done to detect the subsurface stratigraphy of the study area the results show that the subsurface section consists of alternated units of limestone clay marly limestone and dolomitic limestone and the thickness of clay unit ranged from 10 to 40 m nine dipole dipole sections have also been constructed to give a clearer picture of the subsurface at the study area the length of each dipole dipole section is 235 m with a electrode spacing ranging between 5 and 25 m the res2dinv software was used for processing and interpretation of field data the dipole dipole sections at the upper plateau display high resistivity values at most parts of the plateau twelve shallow seismic refraction profiles are measured at selected locations for the dipole sections to define the interface between the fractured limestone and the upper surface of the clay layer each profile consists of 24 geophones with a geophone spacing of 2 3 m interpretation of seismic data indicates that the surface layer of the upper plateau consists of fractured limestone with a velocity range of 1 16 1 56 km s and another layer of compacted clay with a velocity range of 1 38 1 88 km s furthermore the surface layer of the middle plateau consists of marl and marly limestone with a velocity about 2 1 km s and its underlying layer consists of massive limestone with a velocity of 4 94 km s

u pb age constraints on dinosaur rise from south brazil abstract triassic dinosaurs from south brazil are considered as some of the oldest known worldwide but their precise correlation to other early dinosaur occurrences have proven difficult the problem of such long distance faunal correlations has been exacerbated by reliance on an equivocal tetrapod biostratigraphy and the lack of palynomorphs and other age bearing microfossils here we present new high precision u pb zircon geochronology ca id tims method from two classical dinosaur bearing fossil sites in south brazil a weighted mean 206pb 238u date of 233 23 0 73 ma 2 complete uncertainty from the santa maria formation and a single zircon 206pb 238u date of 225 42 0 37 ma representing the maximum age of the caturrita formation the new age results combined with available geochronology from other triassic dinosauromorph occurrences allow establishing a chronostratigraphic framework for the late triassic appearance of dinosaurs in western pangea within this context the major macroevolutionary events associated with the rise of dinosaurs can be recognized and their possible links to coeval paleoenvironmental and biotic shifts can be examined

the effect of magmatic intrusions on coalbed methane reservoir characteristics a case study from the hoskissons coalbed gunnedah basin australia magmatic intrusions can deteriorate coalbed methane reservoir quality by precipitating minerals in natural fracture and cleat system to date the effect of magmatic intrusions on coal rank and maturity has been studied extensively however their impact on fluid flow capacity and gas content is poorly investigated this study evaluates the impact of magmatic intrusions on reservoir characteristics of the hoskissons coal interval in the gunnedah basin eastern australia where numerous coal intrusion associations exist drill stem test dst borehole image logs and core data are used to determine fluid flow characteristics gas content and quality in 14 wells across the gunnedah basin the integration of borehole image logs and dst data analysis enables us to determine the existence openness and hydraulic conductivity of natural fracture and cleat systems in the hoskissons coal interval in addition available desorption canister data gas composition data and conventional well logs are interpreted to investigate probable thermal effect on gas content our analyses of different datasets reveal that the thickness of intrusions and their positions with respect to the hoskissons coal interval are variable in the studied wells permeability varies from 1091 md down to zero owing to heterogeneous fracture and cleat systems interpreted natural fracture cleat systems are well correlated with measured permeability from dst data analysis this highlights the role of open natural fractures cleats in fluid flow characteristics of the hoskissons coal interval results indicate that the mineralizing effect of hydro thermal fluids derived either from magmatic intrusions or coal itself is not a controlling factor in fluid flow capacity of the hoskissons coal interval in the studied wells this is described by either the distance between coal section and major intrusions in some wells or perhaps emplacement of intrusive bodies prior to development of cleat and natural fracture networks the destructive impact of intrusions on permeability is observed in one of the studied wells in which in situ stress perturbation is large due to presence of magmatic intrusions in sedimentary rocks variable in situ stress orientation can decrease fracture connectivity and consequently fluid flow properties are affected gas content largely varies in heat affected coal intervals this signature is the result of thermal effect fading with distance and is more pronounced when intrusions are in close proximity to coal intervals gas composition is variable in the studied wells gas composition data indicate that high quality desorbed gas with methane concentration higher than 90 could be found even in coal intervals which are heavily intruded c 2016 elsevier b v all rights reserved

tethyan magnetostratigraphy from pizzo mondello sicily and correlation to the late triassic newark astrochronological polarity time scale we present the magnetostratigraphy and stable isotope stratigraphy from an expanded 430 m thick upper triassic marine limestone section at pizzo mondello sicily and review published biostratigraphic information that can be used to defi ne the location of the conodont carnian norian and norianrhaetian boundaries in this section pizzo mondello offers good potential for magnetostratigraphic correlation of marine biostratigraphic and chemostratigraphic data with the continental newark astrochronological polarity time scale apts for development of an integrated late triassic time scale the relatively stable average values of 18 o centered on 0 are a strong indication that the cherty limestone at pizzo mondello suffered very little diagenetic overprinting the conodont carnian norian boundary is located 12 5 m above a positive shift of 13 c a statistical approach was applied to evaluate various pizzo mondello to newark magnetostratigraphic correlations two correlation options have the highest correlation coeffi cients in option 1 the base of pizzo mondello correlates with the middle part of the newark apts whereas in option 2 the base of pizzo mondello starts toward the early part of the newark apts we prefer option 2 in which the carnian norian boundary based on conodonts as well as its closely associated positive 13 c shift correspond to newark magnetozone e7 at ca 228 227 ma adopting newark astrochronology implying a long norian with a duration of 20 m y and a rhaetian of 6 m y duration these ages are in fact not inconsistent with the few high quality radiometric dates that are available for late triassic time scale calibration based on its good exposure accessibility stratigraphic thickness and continuity and multiple chronostratigraphic correlation possibilities we propose pizzo mondello as global stratigraphic section and point for the base of the norian

ecology of extant nummulitids and other larger benthic foraminifera applications in palaeoenvironmental analysis abstract larger benthic foraminifera lbf are important contributors to modern and ancient tropical shallow marine sediments over the past 30 years a substantial body of literature has built up on the ecology of modern lbf especially in terms of their environmentally sensitive depth distribution reproductive strategy and morphology and the symbiotic relationship between many larger foraminifera and photosynthetic algae over the same period the extinct genus nummulites which is abundant in eocene sediments of southern europe north africa and the arabian peninsula has increasingly been studied principally because significant volumes of hydrocarbons have been discovered reservoired within nummulitic limestones offshore tunisia and libya the modern ecological studies of lbf provide a powerful tool with which to develop palaeoecological models for fossil nummulites and other symbiont bearing larger foraminifera in the rock record

tectonic controls on carbonate platform evolution in southern papua new guinea passive margin to foreland basin the middle oligocene collision of the northern margin of the australian craton with a complex subduction system resulted in emplacement of a thrust mass and formation of a foreland basin that extended from the coral sea to the indian ocean the distribution of carbonate platform facies in southwestern papua new guinea reflects the transition from an eocene passive margin setting to the early stages of foreland basin evolution the initial basin configuration with terrigenous sedimentation confined to the proximal foredeep allowed carbonate deposition in the shallow environment adjacent to the peripheral forebulge subsequent southward migration of the basin resulted in a rapid increase in the area and thickness of carbonate platform deposition when the proximal foredeep became filled by detritus shed from the emerging orogen clastic sediments buried the platform and terminated carbonate deposition the history of the southern papua new guinea carbonate platform illustrates the paradox of carbonate deposition within the foreland basin whereby basin configuration initially encourages thick and extensive carbonate deposition but inevitably leads to terrigenous inundation and the demise of the carbonate platform

development of a papua new guinean onshore carbonate reservoir a comparative borehole image fmi and petrographic evaluation abstract the depositional and diagenetic controls on carbonate platform evolution are notoriously heterogeneous and difficult to determine from standard subsurface wireline logging techniques here a combined borehole image fmi fullbore formation microimager and petrographic study allowed evaluation of depositional and diagenetic trends across an australasian subsurface buildup that is a major recent gas discovery the elk and antelope gas fields are hosted in tertiary reefal platformal and associated deep water carbonates in the present day foothills region of the fold and thrust belt in the gulf province of papua new guinea a full suite of fmi logs 2800 m and 292 thin sections mainly from sidewall cores and cuttings from both platform flank and shallow water deposits were evaluated during this study despite the obvious scale differences between the datasets there was some correlation between the independent petrography and fmi studies for a picking major facies boundaries and b interpretation of depositional environments the latter particularly for slope and deep water deposits however thin section petrography proved critical in understanding primary depositional textures and secondary alteration features through the shallow water carbonates where complex diagenetic overprinting had strongly impacted original fabric and or in regions affected by gas smearing the petrographic study allowed more detailed examination of diagenesis and its impact on rock fabric which links to the fmi textures component analysis and depositional textures identified in thin section are good indicators of original depositional environment full fmi coverage allowed textural definition on a dm m scale identification and characterisation of vertical changes and likely large scale variations in depositional environments and sequences it was clear from combining the results of the two studies that diagenesis as well as depositional fabric had a strong impact on resultant fmi facies the diagenetic overprinting would have been difficult to extract from the fmi data without the benefit of the petrographic work this study shows the merits of selective petrographic analysis to calibrate the quality of facies interpretation from fmi images and proved critical for enhancing and in places revising initial fmi interpretations

parallel trends in organic and inorganic carbon isotopes across the permian triassic boundary stable carbon isotope ratios in both inorganic and organic reservoirs have been widely applied to model environmental and sedimentological changes on a global scale most studies dealing with major extinction events have used the record of inorganic carbon in this paper the authors report the relation between shifts in carbon 13 content of organic matter and coexisting carbonate fractions at a major extinction event the permian triassic boundary they found that both delta sup 13 c sub carb and delta sup 13 c sub org of the surface ocean varied dramatically across the boundary but the fractionation delta sup 13 c between organic matter and carbonate remained constant this result appreciably restricts the interpretation of changes in the carbon cycle during this critical interval the new data are best explained by a combination of two mechanisms for variation in delta sup 13 c sub carb 1 burial and erosion of organic carbon with a long time constant and 2 sequestration of organic carbon into shallow and deep oceanic reservoirs with a shorter time constant for application to their case the first mechanism is limited by possible buildup of marine pco sub 2 which would increase the isotopic fractionation factor the second mechanism is limited in application to short term transient variations in delta sup 13 c modelingmore of the carbon cycle and its variations of delta sup 13 c must take both mechanisms into account less

global triassic tetrapod biostratigraphy and biochronology abstract eight temporally successive assemblage zones of tetrapod fossils provide the basis for dividing triassic time into eight land vertebrate faunachrons these land vertebrate faunachrons their type assemblage zones and their approximate correlation to the standard global chronostratigraphic scale are ascending order 1 lootsbergian lystrosaurus assemblage zone balfour katberg and burgersdorp formations karoo basin south africa late dorashamian induan 2 nonesian cynognathus assemblage zone burgersdorp formation karoo basin south africa olenikian 3 perovkan shansiodon assemblage zone donguz formation russian urals anisian 4 berdyankian mastodonsaurus assemblage zone bukobay formation russian urals ladinian early carnian 5 otischalkian paleorhinus assemblage zone chinle group chinle basin usa late early to early late carnian 6 adamanian rutiodon assemblage zone chinle group chinle basin usa latest carnian 7 revueltian pseudopalatus assemblage zone chinle group chinle basin usa norian 8 apachean redondasaurus assemblage zone chinle group chinle basin usa rhaetian the triassic land vertebrate faunachrons provide a framework for the correlation of triassic nonmarine deposits with a temporal resolution comparable to the seven triassic stage ages of the standard global chronostratigraphic scale

integrated 3 d reservoir modeling based on 3 d seismic the tertiary malampaya and camago buildups offshore palawan philippines three dimensional 3 d seismic interpretation and drilling results indicate complex sedimentary geometries of the malampaya and camago build ups offshore palawan philippines with localized progradation due to unidirectional offbank transport alternating with vertical aggradation successive reduction of size during buildup growth and backstepping of the protected landward margin in response to transgression ultimately appear to have triggered the demise of carbonate production and platform drowning the shallow water platform top sediments repeatedly show signs of subaerial exposure before reflooding a modeling functionality was developed to allow development of multiple scenario 3 d reservoir models in an exploration or appraisal stage the model enables merging of seismic scale observations based on 3 d volume and horizon analyses with subseismic scale information from well data however inherent noise within the seismic data introduced by the complex buildup morphology has resulted in inconsistent attribute distribution and fault dimming these difficulties are compounded by erratic velocity distribution within the limestone nonhyperbolic move out and a narrow relatively low frequency spectrum all of which prevent the use of the 3 d seismic volume as hard data but rather allow its use as a soft constraint for guiding the geological interpretation and ultimately the modeling process seismic data quality in such complex morphologic settings and scarcity of well data hamper greatly the use of geostatistically driven modeling approaches therefore a new functionality was developed within shell s proprietary integrated 3 d modeling suite geocap which allows deterministic model reservoirs using seismic horizon and volume interpretation sequence and cyclo stratigraphic architecture and the concept of reservoir rock type seismic velocity in clean carbonate formations is predominantly a function of porosity distribution to assess time to depth conversion uncertainty the reservoir rock type based models were first produced in the time domain only after differential 3 d depth conversion of these models could the scenarios be reconstructed in the depth domain the depth models subsequently were used to derive permeability and saturation 3 d distortions and thus hydrocarbon volumes for each deterministic scenario the models were then used for simulation purposes

mesozoic climates general circulation models and the rock record abstract general circulation models gcms use the laws of physics and an understanding of past geography to simulate climatic responses they are objective in character however they tend to require powerful computers to handle vast numbers of calculations nevertheless it is now possible to compare results from different gcms for a range of times and over a wide range of parameterisations for the past present and future e g in terms of predictions of surface air temperature surface moisture precipitation etc gcms are currently producing simulated climate predictions for the mesozoic which compare favourably with the distributions of climatically sensitive facies e g coals evaporites and palaeosols they can be used effectively in the prediction of oceanic upwelling sites and the distribution of petroleum source rocks and phosphorites models also produce evaluations of other parameters that do not leave a geological record e g cloud cover snow cover and equivocal phenomena such as storminess parameterisation of sub grid scale processes is the main weakness in gcms e g land surfaces convection cloud behaviour and model output for continental interiors is still too cold in winter by comparison with palaeontological data the sedimentary and palaeontological record provides an important way that gcms may themselves be evaluated and this is important because the same gcms are being used currently to predict possible changes in future climate the mesozoic earth was by comparison with the present an alien world as we illustrate here by reference to late triassic late jurassic and late cretaceous simulations dense forests grew close to both poles but experienced months long daylight in warm summers and months long darkness in cold snowy winters ocean depths were warm 8 c or more to the ocean floor and reefs with corals grew 10 of latitude further north and south than at the present time the whole earth was warmer than now by 6 c or more giving more atmospheric humidity and a greatly enhanced hydrological cycle much of the rainfall was predominantly convective in character often focused over the oceans and leaving major desert expanses on the continental areas polar ice sheets are unlikely to have been present because of the high summer temperatures achieved the model indicates extensive sea ice in the nearly enclosed arctic seaway through a large portion of the year during the late cretaceous and the possibility of sea ice in adjacent parts of the midwest seaway over north america the triassic world was a predominantly warm world the model output for evaporation and precipitation conforming well with the known distributions of evaporites calcretes and other climatically sensitive facies for that time the message from the geological record is clear through the phanerozoic earth s climate has changed significantly both on a variety of time scales and over a range of climatic states usually baldly referred to as greenhouse and icehouse although these terms disguise more subtle states between these extremes any notion that the climate can remain constant for the convenience of one species of anthropoid is a delusion although the recent rate of climatic change is exceptional

taphonomy of some gondwana vertebrate assemblages of india abstract the gondwana formations of india comprising a thick succession of permo mesozoic continental sedimentary rocks occur in rift basins formed within the indian plate successions developed in some of the gondwana basins namely pranhita godavari damodar satpura and son mahanadi contain an array of vertebrate fossil assemblages among the four basins the pranhita godavari basin contains vertebrate assemblages from late permian middle and late triassic and early jurassic sediments an early triassic assemblage is known to occur in the damodar basin the satpura basin has yielded a middle triassic assemblage while a late triassic assemblage is known from the son mahanadi basin all these assemblages are confined mainly to the fluvial red bed successions taphonomic aspects of some of the assemblages of these gondwana basins are described here for the first time on the basis of the nature of occurrences of the skeletal assemblages six major taphonomic types termed here as a f have been identified from the gondwana basins of india type a includes complete articulated or semi articulated skeletons type b exhibits disarticulated skeletons of a large number of monospecific individuals type c is characterized by disassociated bones of monospecific individuals in a log jam condition type d exemplifies disarticulated bone assemblage of mixed individuals while isolated remains of single individuals belong to type e type f typifies isolated fragmentary bones analyses of these skeletal assemblages provide considerable information of death transportation and burial of the terrestrial vertebrates these results when integrated with the sedimentary features of the host rocks provide additional palaeoenvironmental and palaeocological information

distribution and diversity patterns of triassic cynodonts therapsida cynodontia in gondwana abstract cynodonts are an important component of triassic tetrapod faunas and are frequently one of the dominant groups a summary of their record during the triassic of gondwana is presented cynodonts are represented by 63 species 57 genera in gondwana with diversification peaks occurring during the late anisian particularly in africa and the carnian of south america and india data on the number of faunas of each age and the duration in millions of years estimated for these faunas were integrated with cynodont generic diversity values one of the most important turnovers in cynodonts occurred at the late olenekian anisian involving changes in two directions a the record of complex bucco lingually expanded gomphodont postcanines with traversodontid cynodonts already representing an important group at the end of the anisian b the record particularly during the anisian of significantly large sized cynodonts e g cynognathus and diademodon with basal skull length between 30 to 40 cm considering that the global maximum peak of cynodont diversity is during the norian rhaetian the diversity of gondwanan cynodonts for that time eight taxa is remarkably low

assessment of subsurface structural elements around greater cairo by using integrated geophysical tools geophysical techniques such as gravity magnetic and seismology are perfect tools for detecting subsurface structures of local regional as well as of global scales the study of the earthquake records can be used for differentiating the active and non active fault elements in the current study more than 2 200 land magnetic stations have been measured using two proton magnetometers the data are corrected for diurnal variations and then reduced by the international geomagnetic reference field the corrected data have been interpreted by different techniques after filtering the data to separate shallow sources basaltic sheet from the deep sources basement complex both euler deconvolution and 3 d magnetic modeling were carried out the results of interpretation indicate that the depth to the upper surface of basaltic sheet ranges from 10 to 600 m depth to the lower surface ranges from 60 to 750 m while the thickness of the basaltic sheet varies from 10 to 450 m moreover gravity measurements are conducted at 2 250 stations using a cg 3 gravimeter the measured values are corrected to construct a bouger anomaly map the least squares technique is then applied for regional residual separation the third order of least squares is found to be the most suitable to separate the residual anomalies from the regional one the resultant third order residual gravity map is used to delineate the structural fault systems of different characteristic trends the trends show an nw se trend parallel to that of gulf of suez an ne sw trend parallel to the gulf of aqaba and an e w trend parallel to that of the mediterranean sea taking seismological records into consideration it is found that most of the 24 earthquake events recorded in the study area are located on fault elements this gives an indication that the delineated fault elements are active