the upper ordovician black shales of southern quebec canada and their significance for naturally occurring hydrocarbons in shallow groundwater abstract shale gas exploration in the st lawrence platform of southern quebec eastern canada focussed on the upper ordovician utica shale from 2006 to 2010 during which 28 wells were drilled 18 of which were fracked the st lawrence platform is thus considered as a pristine geological domain where potential environmental effects of fracking can be evaluated relative to the natural baseline conditions of the shallow aquifers in the saint edouard area southwest of quebec city it has been shown that groundwater carries variable and locally high levels of naturally occurring dissolved hydrocarbons in which thermogenic ethane and propane can be found fifteen shallow 30 147 m wells were drilled into bedrock and sampled cores and cuttings with the purpose of characterizing the shallow bedrock in a shale gas pre development context the shallow bedrock geology is made of three upper ordovician clastic formations the lotbiniere and les fonds formations are time and facies correlative with the utica shale present at a depth of 1 5 to 2 km in this area they are dominated by calcareous black shales with minor siltstone and micrite beds the nicolet formation is the youngest unit of the area and consists of gray to dark gray shales with locally abundant thick siltstone and fine grained sandstone beds the organic matter in the lotbiniere and les fonds formations is represented by solid bitumen with subordinate liptinite algae graptolites and chitinozoans representing normal marine type ii kerogen both formations are at the post peak hydrocarbon generation as indicated by the equivalent random vitrinite reflectance of 0 94 to 1 04 rock eval data support the type ii nature of the kerogen and the late oil window maturation level hydrocarbon extracts from the three formations have yielded high to low concentrations of c1 to c6 for all units an upward decrease in total volatiles c1 c2 c3 together with an increase in the gas dryness ratio c1 c2 c3 is recorded the transitions occurring at depths shallower than 50 m where the shales are more fractured the upward increase in the gas dryness ratio results from the more significant reduction of ethane and propane concentrations compared to that of methane consistent with the dryness ratio trend the 13 c vpdb values of methane change from thermogenic values 50 for deeper samples to more biogenic negative values 2 h vsmow trend of more negative values at shallower depths is noted the 13 c vpdb and 2 h vsmow values of rock hosted methane indicate that samples at shallow depth recorded a microbial influence it is proposed that diffusion and some microbial degradation of hydrocarbons are responsible for the decrease of rock volatiles and the in situ generation of biogenic methane in the shales at shallow depths to mix with the in situ thermogenic methane the utica shale is a very good source rock with high generation potential however thermogenic volatiles can also originate from shallower units with much shorter migration pathways the mixed thermogenic and biogenic methane in the groundwater results from fracture enhanced diffusion and biodegradation of volatiles at shallow depths

closed form solution for finger width in sandy soils at different water contents wetting front instability and gravity driven fingers can occur during infiltration in sandy soil these soils overlay many major aquifers finger width and velocity are important parameters in predicting the risk of groundwater pollution in these soils in previous studies closed form solutions were developed for air dry soil in uniformly wet soils where the fingers are much wider predictive finger width equations have failed so far in this paper we simplify further the parlange hill closed form solution for dry soil and show that by taking hysteresis into account it applies to fingers emanating from a point source in a sandy test soil at two widely different moisture contents

preferential flow of a nonaqueous phase liquid in dry sand geotechnical centrifuge testing is used to examine the preferential fingered flow of a nonaqueous phase liquid napl in a uniform dry sand the results of nine experiments containing a total of 87 observations of napl finger behavior are analyzed the observed finger tip velocities range from 0 01 to 0 3 cm s while the observed finger widths range from 0 3 to 3 6 cm from the experimental data it is concluded that asymptotically the napl fingers are not fully saturated for comparison the behavior of water fingers is examined using the same experimental setup in contrast to the napl fingers and in agreement with other work reported in the literature the water fingers are found to be fully saturated in addition it is confirmed that the water finger properties can be well predicted from known porous medium and fluid properties a scaling analysis is presented that allows the napl finger properties to be inferred from models developed to describe water finger properties the analysis predicts napl finger velocities to within 15 and napl finger widths to within 50 if both finger types are assumed saturated by adjusting the analysis to account for the fact that the napl fingers are not fully saturated napl finger widths can be predicted within to 10 and napl finger velocities to within 30

numerical modeling of the productivity of vertical to shallowly dipping fractured zones in crystalline rocks groundwater resources in crystalline rock are typically associated with the weathered zone and regional sub vertical faults that are well connected to the surface however some sub horizontal and shallowly dipping fractured zones can also be highly productive aquifers in this paper numerical simulations of a conceptual hydrogeological model show that the flow to such strongly transmissive fractured zones is controlled by their transmissivity or by their deepening structure while leakage through the overlying rock units is generally the limiting factor recharge always occurs at least close to the outcrop of the fractured zone where the overlying rock is thinner and guarantees the availability of some groundwater at small dip angles recharge extends spatially and the flow within the fractured zone may even become the limiting factor when the hydraulic conductivity of the overlying rock is not less than two orders of magnitude smaller than the fractured zone transmissivity this is precisely the case of the ploemeur aquifer brittany france located in a crystalline rock geologic setting where groundwater in a shallowly dipping fractured zone is used as the source of water supply for a nearby city of 20 000 people simulation results show that the fractured zones may represent potential aquifers under a large variety of hydrogeological conditions aquifers in shallowly dipping structures differ strongly from those located in regional subvertical fault zones in terms of flow patterns and thus supposedly in terms of management of the groundwater resource they are more local than regional in scale and consequently do not require regional fracture connectivity the leakage through the overlying rock unit enhances water quality finally we argue that the potential widespread occurrence of these alternative and possibly less accessible resources should promote the development of appropriate identification methods

graptolites as indicators of the temperature histories of rocks a pilot study of the optical properties of graptolite skeletal materials shows progressive changes of reflectance bireflectance refractive index and absorptive index produced by temperature changes related to depth of burial samples of lower ordovician to upper silurian graptolites were selected from across canada from locations where the conodont alteration indices of adjacent conodont collections provide a control index of temperature the reaction to temperature of graptolite skeletal material appears to be similar to that of bitumen but somewhat different to that of the vitrinite and liptinite maceral components of coal maximum reflectance in oil and bireflectance appear to be the characteristics most diagnostic of maximum temperature and both show progressively higher rates of increase at higher temperatures these factors show potential for more sensitive discrimination of temperatures at high levels of conodont alteration indices the optical properties of graptolites may perhaps provide a useful tool for unravelling the post depositional histories of lower palaeozoic rocks in deformed belts

the significance of graptolite reflectance in regional thermal maturity studies queen elizabeth islands arctic canada abstract variations in reflectance and bireflectance of graptolites taken from the cape phillips formation in the queen elizabeth islands arctic canada are documented graptolites taken from core samples from melville island possess a wide range of reflectance 1 75 3 90 r0max graptolites taken from outcrop samples from the other islands have a much narrower reflectance distribution 0 57 0 81 r0max the latter indicate that the organic matter is in the mature stage of hydrocarbon generation conodont colour alteration indices in strata from arctic canada and in the cape phillips formation in eldridge bay e 79 melville island are low 1 1 5 and agree with the low reflectance of the cape phillips graptolites the higher maximum reflectance values of the melville island graptolites indicate that the host sediments have experienced deeper burial and exposure to elevated temperatures compared to graptolites in the same formation of other islands this study demonstrates that graptolite reflectance can delineate relatively accurately the thermal conditions that sediments enclosing them have experienced and when combined with bitumen reflectance and stratigraphic and structural evidence graptolite reflectance can be useful in assessment of thermal maturity and thickness of eroded section in lower palaezoic successions

the lateral and vertical reflectance and petrological variation of a heat affected bituminous coal seam from southeastern british columbia canada abstract thermally altered pods of coal of very high rank have been observed in a high volatile bituminous coal seam in the eastern side of eagle mountain elk valley coalfield british columbia rank changes have been measured over a strike distance of 7 5 m from 1 24 to 7 1 r o max corresponding to a rank gradient of 0 78 r o m 1 petrologically unaltered to extremely altered vitrinite showing nongranular basic anisotropy mosaic textured liptinite and pyrolytic carbon are the most abundant components the limited presence of mosaic on vitrinite is an indication that the coal seam may have been weathered prior to being heat affected evidence points to localized temperatures as high as 1 000 c which could have been caused by a lightning strike the eastern side of eagle mountain has experienced higher temperatures than the western side and it appears that the heat front and zone of alteration have an irregular pattern pointing to saturation of parts of the coal seam by water four types of pyrolytic carbon having distinct morphology anisotrophy and optical path with increasing temperature were observed reflectance of pyrolytic carbon falls within the zone of heat affected coals whereas the optical path of heat affected seam 15 samples is different from that of fresh coal with increasing rank finally the reflectance of vitrinite in heat affected coal is higher than the reflectance of vitrinite in carbonaceous shale in the seam 15 section

the silurian qusaiba hot shales of saudi arabia an integrated assessment of thermal maturity abstract the lower silurian qusaiba hot shales qhs are proven source rocks for oil within the paleozoic and possibly some of the mesozoic reservoirs in saudi arabia moreover these shales have oil shale potential where they are immature and shallow enough for mining as well as unconventional shale oil and shale gas potential in areas where they are within oil maturity and gas maturity levels respectively the qhs were deposited in relatively shallow marine environments under anoxic water conditions resulting in accumulation of amorphous kerogen organic walled graptolites and acritarchs across the arabian basin organic matter quality does not show much variation for the qhs but the maturity varies greatly as a result of varying burial history thermal maturity assessment of shale source rocks that lack vitrinite such as the qusaiba hot shales continues to be challenging especially where conflicting measurements are obtained from different sources this paper presents an integrated assessment of qhs thermal maturity parameters based on cores from 13 carefully selected boreholes that based on regional basin models are believed to cover a wide maturity range ca 0 5 to 2 0 ro we conducted some analyses on kerogen maceral petrography graptolite reflectance uv fluorescence whole rock pyrolysis raman spectroscopy of graptolite and other analyses on bitumen extracts gc and gc ms of saturate and aromatic fractions and ftir spectroscopy of the asphaltene fraction we show that using many thermal maturity parameters reduces uncertainty significantly and we therefore recommend that graptolite reflectance analyses should be conducted in support of other maturity indicators proper reflectivity measurements of the graptolites set the reference for comparison of other maturity parameters obtained from petrographic geochemical and spectroscopic techniques our work provides a template by which qusaiba thermal maturity can be more accurately estimated when only a limited set of maturity parameters is available

graptolite derived organic matter in the wufeng longmaxi formations upper ordovician lower silurian of southeastern chongqing china implications for gas shale evaluation abstract the organic rich shales of the wufeng longmaxi formations ordovician silurian are one of the most important hydrocarbon source rocks and shale gas exploration targets in china graptolites are abundant in these shales but their contribution to the dispersed organic matter om has been overlooked this lack of attention could seriously affect the evaluation of om type om maturity hydrocarbon generation potential reservoir characteristics and gas content of these shales optical microscope and focused ion beam scanning electron microscope fib sem techniques were employed to describe the optical characteristics and micro nanopores of the graptolites to determine the contribution of the graptolites and to evaluate the thermal maturity of the wufeng longmaxi formations non granular graptolites which show a stronger anisotropy and higher reflectance under polarized light than the granular graptolites were primarily observed in these sediments graptolites account for 20 93 of the dispersed om in the wufeng longmaxi formations and the level of their contribution has been attributed to the radiation of graptolites at the late ordovician kaptian and the recovery of graptolites at the early silurian rhuddanian the bireflectance values of the non granular graptolites fall between 2 22 and 4 32 indicating a behavior similar to biaxial anthracitic vitrinite the equivalent vitrinite reflectance eqvro values of the sediments in the wufeng longmaxi formations calculated from the mean maximum reflectance of non granular graptolite fall in the range of 3 08 4 29 and these values have a precision that is greater than in previous studies on the wufeng longmaxi formations abundant organic pores were observed in the non granular graptolites and they are aligned parallel to the fusellar layers of the graptolites this indicates that the fusellar layers of non granular graptolites controlled the development and distribution of organic pores such abundant organic pores played a significant role in the accumulation of shale gas in the wufeng longmaxi formations of the upper yangtze platform

optical characteristics of graptolite bearing sediments and its implication for thermal maturity assessment abstract graptolite reflectance was thought to be one of the most useful thermal maturity indicators for graptolite bearing sediments however the relationship between graptolite reflectance and vitrinite reflectance is not well established graptolites especially in the wufeng longmaxi formations from the ordovician to silurian of south china have been mistaken for vitrinite like particles or solid bitumen which results in inconsistent data on the thermal maturity in this paper we have employed optical microscope techniques to describe the detailed optical characteristics of graptolites and solid bitumen in the wufeng longmaxi formations laboratory simulation of maturation was used to determine the relationship between graptolite reflectance and vitrinite reflectance the organic constituents in the wufeng longmaxi formations are mainly composed of graptolites and solid bitumen granular and non granular graptolites were observed in the wufeng longmaxi formations with non granular as the most common texture solid bitumen can be distinguished from non granular graptolites by its coarse surface weaker anisotropy and lower random reflectance the combination of non polarized and polarized light is very helpful to distinguish solid bitumen from graptolite for comparison organic material from the early ordovician alum shale formation of sweden and estonia was also studied the macerals of the alum shales are mainly composed of lamalginites mineral bituminous groundmasses graptolites and solid bitumen the major textures of the graptolites in the sweden and estonia sediments are non granular and granular respectively both non granular graptolite and vitrinite reflectances display a systematic increase with the increase of heating temperature and time the granular graptolites in the estonian sample were gradually changed to non granular graptolites following laboratory simulated maturation indicating that granular graptolites can transform into non granular graptolites with maturation solid bitumen in the wufeng longmaxi formations was derived from the solid residue of kerogen and or post oil bitumen the graptolite random reflectance is a better thermal maturity indicator than graptolite maximum reflectance and is more precise due to the smaller standard deviation several equations are proposed to determine the thermal maturity of the graptolite bearing sediments based on graptolite random reflectance graptolite maximum reflectance and solid bitumen random reflectance

pore structure of the graptolite derived om in the longmaxi shale southeastern upper yangtze region china abstract the lower silurian longmaxi shale in the southeastern upper yangtze region which has been the main target for shale gas exploration and production in china is black marine organic rich shale and rich in graptolites graptolites usually only periderms preserved in shales are important organic component of the longmaxi shale however the pore structure of graptolite periderms and its contribution to gas storage has not yet been studied before a combination of optical microscopy for identification and mark of graptolite and scanning electron microscope sem for pore observations were conducted for the longamxi shale samples results show that pores are anisotropic developed in the longmaxi graptolite periderms and greatly associated with their fine structure micrometer sized fractures and spindle shaped pores between cortical fibrils in the cortical bandage are greatly developed at section parallel to the bedding while they are rare at section perpendicular to the bedding besides numerous sapropel detritus rich in nanometer sized pores are discretely distributed in the shale though graptolite periderms are low porosity from sem image analysis microfractures and elongated pores along the graptolite periderm wall may still make the graptolite an interconnected system together with the discrete porous sapropel detritus in shale these graptolite derived organic matter om may form an interconnected organic pore system in the shale the difference of pore development observed in graptolite periderms and sapropel detritus also give us new insight for the organic pore heterogeneity study the om composition their fine structure and orientation in the rock may be important factors controlling om pore development the combination of identifying om type under optical microscopy and pores observation under sem for may be an effective method to study the om pore development especially in shale that contain more om

temporal evolution of age data under transient pumping conditions while most age data derived from tracers have been analyzed in steady state flow conditions we determine their temporal evolution when starting a pumping our study is based on a model made up of a shallowly dipping aquifer overlain by a less permeable aquitard characteristic of the crystalline aquifer of pl meur brittany france under a pseudo transient flow assumption instantaneous shift between two steady state flow fields we solve the transport equation with a backward particle tracking method and determine the temporal evolution of the concentrations at the pumping well of cfc 11 cfc 12 cfc 113 and sf6 apparent ages evolve because of the modifications of the flow pattern and because of the non linear evolution of the tracer atmospheric concentrations to identify the respective role of these two causes we propose two successive analyses we first convolute residence time distributions initially arising at different times at the same sampling time we secondly convolute one residence time distribution at various sampling times we show that flow pattern modifications control the apparent ages evolution in the first pumping year when the residence time distribution is modified from a piston like distribution to a much broader distribution in the first pumping year the apparent age evolution contains transient information that can be used to better constrain hydrogeological systems and slightly compensate for the small number of tracers later the residence time distribution hardly evolves and apparent ages only evolve because of the tracer atmospheric concentrations in this phase apparent age time series do not reflect any evolution in the flow pattern

the organic petrology of graptolites and maturity assessment of the wufeng longmaxi formations from chongqing china insights from reflectance cross plot analysis abstract the wufeng longmaxi formations ordovician silurian contain abundant graptolite bearing shales which have proven to be one of the most successful shale gas exploration targets in china and can provide an opportunity to study the organic petrology of graptolites organic petrology analysis has been conducted on these organic rich shales in order to depict the shape of graptolite reflectance indicating surface gris and their organic maturity granular and non granular graptolites have been observed in the studied sediments and non granular graptolites were the major graptolite species the strong positive correlation between the maximum reflectance rmax and bireflectance of graptolites indicates that the graptolites display stronger anisotropy with maturation a linear coalification path of graptolite fragments was observed in the studied sediments a remarkable decrease in the minimum reflectance rmin values of graptolites was observed when rmax exceeds 6 the samples with lower thermal maturity rmax 2 tend to be biaxial neutral whereas higher rank samples display biaxial negative characteristics the gris shape becomes more oblate with maturation the wufeng longmaxi shales from the southeastern chongqing and wuxi areas of the chongqing municipality china are post mature and in the dry gas zone whereas samples from the chengkou area of the chongqing municipality china are still in the oil window their different burial and thermal histories controlled their thermal maturity

reflectance cross plot analysis of graptolites from the anchi metamorphic region of northern maine u s a abstract reflectance crossplot analysis a graphical technique plotting apparent reflectance maxima and minima against the apparent bireflectance and previously used primarily for interpretation of biaxial vitrinite data is applied to graptolite reflectance data from the subgreenschist and chlorite zones of northern maine u s a to determine the value of the intermediate reflectance axis rint the shape and change in the graptolite reflecting indicating surface gris with rank and calculate random reflectance from the crossplots gris shapes for this region were found to become rapidly oblate with increasing maturation in addition the random reflectance calculated as the arithmetic mean of the three reflectance axes compares favorably with the measured mean random reflectance

assessing thermal maturity of palaeozoic rocks from reflectance of chitinozoa as constrained by geochemical indicators an example from southern ontario canada the reflectance of chitinozoa chr0 was investigated as an alternative technique of determining the level of thermal maturity of organic rich palaeozoic rocks in southern ontario these sedimentary strata which include the ordovician collingwood member and the blue mountain formation as well as the devonian marcellus formation lack vitrinite precluding the application of a standard vitrinite reflectance vr0 technique chr0 shows a proportional increase at marginal to moderate maturities being on average 20 to 25 higher than expected vitrinite reflectance the reflectance data fall into a very narrow range showing a high degree of consistency for each lithostratigraphic unit the average chr0 are as follows collingwood mbr 0 63 georgian bay area and 0 88 toronto area blue mountain fm 0 92 marcellus fm 0 68 correlation with more conventional optical and geochemical maturity parameters obtained from the same set of samples fluorescence of tasmanites leiosphaeridia and gloeocapsomorpha alginite rock eval tmax extract data distribution of terpanes and steranes in extracts indicates that within the area of study the beginning of the catagenetic stage corresponds to chr0 0 65 equivalent vr 0 50 whereas the threshold of significant oil generation is reached at chr0 0 9 equivalent vr 0 70 therefore the blue mountain formation is thermally mature with respect to hydrocarbon generation throughout the whole area of study the collingwood shales are mature only in the toronto area while those occurring in the georgian bay area as well as the marcellus shales have yet to enter the main stage of hydrocarbon generation this integrated approach of assessing thermal maturity shows that chr0 when constrained with other maturity parameters is a very reliable indicator of thermal maturity in lower to middle palaeozoic sedimentary rocks

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

graptolites as fossil geo thermometers and source material of hydrocarbons an overview of four decades of progress abstract the thermal maturity of lower paleozoic graptolite bearing marine sediments which host many hydrocarbon deposits worldwide has long been difficult to determine due to the absence of wood derived vitrinite particles for conventional vitrinite reflectance in 1976 graptolite reflectance was introduced as a new indicator for organic maturity of these deposits and has been used since in many regional studies the majority of these studies however were done on a limited sample set and a limited range of thermal maturity which resulted in a number of controversial views concerning the usefulness of graptolite reflectance as an alternative paleothermal indicator and its correlation with vitrinite reflectance through various proxies in this paper we review previous studies and combine those analyses with new data to assess the physical and chemical characteristics of graptolite periderm with increasing thermal maturity we conclude that graptolite random reflectance gror is a better parameter for the thermal maturity assessment than graptolite maximum reflectance gromax due to the better quality of available data combining published data with results of our study of both natural and heat treated graptolites and vitrinite we present a new correlation between gror and equivalent vitrinite reflectance eqvro as eqvro 0 99gror 0 08 chemical composition of graptolite periderm is similar to vitrinite graptolites are mainly kerogen type ii iii are gas prone and have a substantial hydrocarbon potential lower paleozoic graptolite bearing organic rich sediments are important shale gas source rocks and reservoirs globally and make a significant contribution to worldwide petroleum reserves

arthropod cuticles in coal an abundance of scorpion cuticles from westphalian upper carboniferous coals of yorkshire is described and other records of arthropod cuticles in coals are reviewed the absence of cuticles assignable to arthropod groups other than scorpions is thought to be due to preferential preservation of the unique exocuticle of scorpions it alone is preserved and appears to retain an organic nature the cuticle is recovered from all the lithotypes of humic bituminous coals although it is most common in coals rich in inertinite macerals from the present study it is uncertain whether the scorpions were aquatic or terrestrial the recognition of arthropod cuticle as a coal maceral could aid environmental interpretations the abundance of arthropod cuticle in the coals studied indicates its potential use in correlation and in determining the thermal maturity of sediments

preferential flow in a sandy vadose zone 1 field observation abstract field experiments of water movement in the lower portion of an unsaturated zone i e vadose zone are far more difficult to conduct than those in the root zone thus our concept of the transport mechanism in the vadose zone is still primitive and mainly an extrapolation of our understanding of transport in the root zone recent results from field experiments conducted at the hancock agricultural research station indicated that water and solute applied uniformly to soil surfaces did not flow through the entire vadose zone by using dye tracing and profile excavation field experiments were conducted during the 1987 growing season to examine water flow patterns in the unsaturated zone of the central sand area of wisconsin csaw the results confirmed that preferential flow paths constitute the dominant flow pattern at this location water flowing through the root zone was funneled into concentrated flow paths that occupied only a small portion of the soil matrix in the vadose zone yet accounted for most of the transport the observed phenomena of preferential flow in a sandy vadose zone are discussed in this paper the mechanism and implications of preferential flow are presented in a companion paper

dissolved gases in groundwater and groundwater dating methods how useful for hydrogeological modeling foreword to the special issue one of the major challenges in hydrogeology is the basic spatial lack of continuous data as this is restricted to available boreholes basic information is provided by the measurements of physical parameters e g porosity and permeability at the well scale information related to a larger part of the aquifer are provided for example by continuous measurement of piezometric levels or spring flow temporal information is extremely powerful in order to characterize aquifer functioning globally groundwater dating has thus been developed in order to provide time constraints in aquifer studies

age distribution estimation for karst groundwater issues of parameterization and complexity in inverse modeling by convolution summary convolution modeling is useful for investigating the temporal distribution of groundwater age based on environmental tracers the framework of a quasi transient convolution model that is applicable to twodomain flow in karst aquifers is presented the model was designed to provide an acceptable level of statistical confidence in parameter estimates when only chlorofluorocarbon cfc and tritium 3 h data are available we show how inverse modeling and uncertainty assessment can be used to constrain model parameterization to a level warranted by available data while allowing major aspects of the flow system to be examined as an example the model was applied to water from a pumped well open to the madison aquifer in central usa with input functions of cfc 11 cfc 12 cfc 113 and 3 h and was calibrated to several samples collected during a 16 year period a bimodal age distribution was modeled to represent quick and slow flow less than 50 years old the effects of pumping and hydraulic head on the relative volumetric fractions of these domains were found to be influential factors for transient flow quick flow and slow flow were estimated to be distributed mainly within the age ranges of 0 2 and 26 41 years respectively the fraction of long term flow 50 years was estimated but was not dateable the different tracers had different degrees of influence on parameter estimation and uncertainty assessments where

an overview of pre devonian petroleum systems unique characteristics and elevated risks abstract the radiation of land plants at the onset of the devonian resulted in a change in the character of available biomass which in turn introduced changes to the nature of petroleum systems this study examines the nature of pre devonian petroleum systems prior to this significant evolutionary event conventional hydrocarbon resources have been associated with pre devonian petroleum systems across the globe including the neoproterozoic infracambrian huqf supergroup of the oman basin the riphean vendian sequences of east siberia the cambrian of the murzuq basin the ordovician of the tarim basin and the silurian qusaiba of saudi arabia although individual accumulations can be quite significant e g hassi messaoud has ultimate recoverable reserves of 10 billion barrels the relative importance of pre devonian derived oils is thought to be limited compared to the global conventional resource base with growing interest in unconventional resources the relative importance of these systems is expected to increase as resource plays such as the ordovician utica shale of the appalachian basin the cambrian of china and possibly the silurian of central and eastern europe develop the advanced ages of these systems result in some unique properties and amplify risks that exist in younger petroleum systems differences in the nature of the biomass contributing to pre devonian source rocks may give rise to oils that display unique geochemical characteristics for example there are some precambrian oils where c 29 steranes dominate even though land plants were absent there are also ordovician source rocks dominated by gloeocapsamorpha prisca a primitive prokaryote which yield oils containing limited amounts of c 20 components and nearly lack pristane and phytane the potential for unconventional reservoirs in pre devonian systems may also be highly dependent upon the age of the system as biological evolution influences the availability and nature of biogenic silica an important factor controlling brittleness and fracability literature has shown that biogenic silica from different sources displays varying degrees of resistance to diagenesis which allows the formation of a silica network and influences brittleness for example radiolaria present during the cambrian are more resistant to diagenesis than diatoms which did not evolve until the jurassic risks associated with preservation of hydrocarbons are also amplified in pre devonian petroleum systems many such systems have been exposed to significant thermal stresses resulting in the cracking of oil and wet gas others have had complex tectonic histories potentially resulting in the breaching of seals or changes in pvt conditions that can result in gas loss gas loss may also occur through diffusion from these older reservoirs as a result of long residence times

heating during thrust faulting in the rocky mountains friction or fiction abstract measurement of the levels of organic maturation below and within shear zones of thrust faults in the rocky mountains has revealed no general thermal metamorphism that can be attributed to faulting with the exception of very localized areas with few exceptions the vitrinite reflectance values obtained are in the range expected if the maximum level of organic maturation was produced as a result of increasing temperature during progressive burial accompanying sedimentation only at marias pass evidence has been found to suggest additional maturation as a result of post orogenic burial below the thrust sheets anomalously high vitrinite reflectances obtained from the lewis thrust mcconnell thrust coleman thrust and two unnamed thrusts are restricted to very narrow films immediatly adjacent to or within the shear zone which considering any reasonable thermal conductivity indicates elevated temperatures were very short lived the anomalously high vitrinite reflectances within these films when compared to laboratory heated coals suggest temperatures in the order of 350 650 c were locally generated during faulting such high temperatures are considered to have been generated during stick slip faulting at macro asperities or at ramps on the fault plane where local and possibly transient high frictional stresses existed the absence of evidence for extensive frictional heating supports previous arguments that stable sliding and or low frictional stress must exist during thrusting

chitinozoan reflectance a lower palaeozoic thermal maturity indicator abstract chitinozoan reflectance r ch is an innovative technique of thermal maturation determination suitable for lower palaeozoic sediments where the established reflectance scale vitrinite reflectance r v is not applicable due to the lack of vitrinite reflectance measurements are taken from polished sections of chitinozoa a group of lower palaeozoic organic walled marine microfossils these vase shaped palynomorphs are optically isotropic have thick homogeneous test walls and are easy to identify making then ideal for organic petrology from over 1000 samples collected 54 possessed both chitinozoa and vitrinite enabling direct calibration of the two scales a clear linear relationship exists between the two parameters the equation resulting from this study is r ch 1 152 r v 0 08 with a correlation coefficient of 0 989 there is a suggestion of a maturity discontinuity between 1 and 2 r ch but due to the high sample redundancy rate only 5 of samples possessed both vitrinite and chitinozoa it was not possible to supply more data at this maturity level chitinozoan reflectance is a powerful thermal maturity indicator for lower palaeozoic sediments the technique has significant advantages over its maln rivals particularly the ease of particle identification and the fact that it is independent of facies thus quantitative maturity data with a high spatial and temporal resolution can be gained from pre devonian marine sedimentary sequences

critical considerations when assessing hydrocarbon plays using rock eval pyrolysis and organic petrology data data quality revisited abstract the dramatic increase in exploration for unconventional hydrocarbon resources has inherently fuelled the need for new source rock geochemical data the need for new data comes along with an increasing number of new users many of whom do not possess the background to interpret accurately and evaluate the quality of data sets generated by different geochemical screening techniques e g rock eval pyrolysis vitrinite reflectance here datasets from rock eval pyrolysis vitrinite reflectance and leco toc analyses are scrutinized and compared to show how failing to recognize good vs bad datasets can dramatically change interpretations during prospect or play appraisals detector saturation contamination of the sample with drilling fluid and suppression of both tmax and vitrinite reflectance are examples of complications that could compromise the validity of the results and the play or prospect reviews derived from them in addition misconceptions such as leco toc is better than rock eval 6 toc expressed by many users are a consequence of the lack of understanding of how different screening techniques and instrumentation work a solid understanding of these pitfalls and limitations can provide inexperienced geoscientists and engineers with the required support to improve risk maps for hydrocarbon charge analysis and source rock evaluations when using classic guidelines for interpreting results

influence of igneous intrusions on thermal maturity and optical texture comparison between a bituminous marl and a coal seam of the same maturity abstract the impact of a 120 cm thick dike on dispersed organic matter in the triassic marry harbour mh bituminous marl in the raanes peninsula ellesmere island arctic canada was studied using reflected light microscopy and rock eval pyrolysis results were compared to a coal seam of similar maturity that was thermally altered by an igneous intrusion the mh bituminous marl is mature and within the oil window ro 0 94 whereas the coal is high volatile b bituminous rank ro 0 80 thermal alteration impacted differently the organic rich marl than the coal seam most of the heat generated by the intrusive emplacement in contact with coal is spent transforming coal to coke in the plastic layer zone similar to the process that coal undergoes in industrial coking operations in contrast the thermal alteration of sedimentary rocks occurs over longer distances as a result of the absence of a plastic layer zone the impact zone of the 120 cm thick igneous intrusion was greater in the mh bituminous marl which became thermally altered ro 2 34 at 190 cm from the contact with the dike on the contrary the coal became thermally altered ro 5 0 by a 240 cm alkali basalt intrusion twice the thickness of the mh dike and its impact zone was only 65 cm heat and hot volatile matter produced by the thermal decomposition of organic matter and minerals carbonate dehydration of clay minerals in contact with the igneous intrusion body is transferred through the sedimentary rock matrix by convection through fractures this transformation is evident by the occurrence of the pyrolytic carbon at various distances in the fractured mh marl from contact the hydrogen index hi shows a similar trend to that of the remaining source potential s2 both parameters decrease systematically toward the dike and go through a minimum at 20 cm from the dike contact as the indigenous organic matter is converted to hydrocarbons or devolatilized at the dike contact both s2 and hi have higher values these trends are similar to those of the volatile elements h and cl in the intruded coal seam the free hydrocarbons s1 showed a slightly different trend than s2 and hi it increased initially from 300 cm and reached a maximum at about 190 cm from the dike contact before decreasing continually and reaching a minimum at 20 cm from the contact at the dike contact the s1 increased slightly similar to the hi and s2 the presence of oil droplets trapped in carbonate concretions in combination with the highest value of oil expelled from the source rock based on s1 toc at distance of 190 cm from dike is an indication of the influence of contact metamorphism on oil generation locally furthermore it indicates that intrusion of igneous dikes into the bituminous mh marl resulted in an increase of organic matter maturation locally and in hydrocarbon generation

reflectance measurements of zooclasts and solid bitumen in lower paleozoic shales southern scandinavia correlation to vitrinite reflectance abstract reflectance measurements have been carried out on zooclasts graptolites chitinozoans and vase shaped microfossils and other organic particles vitrinite like particles porous granular vitrinite like particles and solid bitumen in middle cambrian to upper silurian shales from central and southern sweden and the danish island of bornholm baltic sea the most abundant organic components in all the shales are fragments of graptolites and vitrinite like particles the reflectance distribution of these two types of components is largely identical and it is suggested that the vitrinite like particles are fragments of graptolites without any recognizable morphology reflectance measurements of graptolites and vitrinite like particles yield well defined reflectance populations in samples with average r graptolite and average r vitrinite like of 0 75 r o the reflectance distributions are bimodal because of increasing bireflectance and the average reflectance value of the well defined lower reflecting population is arbitrarily used as maturity indicator our results suggest that with increasing thermal maturity the reflectance of graptolites increases faster than the predicted vitrinite reflectance the relationship between graptolite reflectance and equivalent vitrinite reflectance can be expressed by the equation vr eqv 0 73 r graptolite vitrinite like low 0 16 the gas generation window which normally is considered to begin at a vitrinite reflectance of 1 3 r o in post lower paleozoic rocks containing vitrinite starts accordingly at 1 56 r o graptolite reflectance porous granular vitrinite like particles occur in minor amounts and they may represent graptolite fragments with a non smooth surface they generally yield slightly higher reflectance than non granular vitrinite like particles and graptolite fragments the middle cambrian to furongian upper cambrian shales may contain sparse fragments of vase shaped microfossils vsm that seem to follow the maturation trend of chitinozoans in the present sample set the reflectance of chitinozoans and vsm is comparable to that of graptolites at the same level of maturity reflectance measurements of solid bitumen are a poor maturity indicator probably because bitumen can have various origins and morphologies and it may not be indigenous to the host rock

diagenesis and anchimetamorphism in an overthrust belt external domain of the taconian orogen southern canadian applachians ii paleogeothermal gradients derived from maturation of different types of organic matter abstract 3hermal maturation patterns have been established for the external domain of taconian orogen of the southern quebec appalachians between quebec city and the u s border reflectance of three types of organic matter om measured in the same sample shows that graptolite reflectance r g is higher than pyrobitumen reflectance r b which in turn is higher than reflectance of amorphous organic matter r a r g r b and r a are converted to vitrinite equivalent reflectance from which maximum paleotemperatures were calculated inverted diagenesis is preserved in northwest part of the chaudiere nappe to the southeast original burial diagenetic grade was upgraded by later synorogenic heating in the st lawrence lowlands paleogeothermal gradients at maximum burial were 33 37 c km a gradual southwestward increase in maturation level suggests increasing post taconian burial depth from 4 6 to 6 7 km indicating an increasing thickness of eroded rocks from northeast to southwest along logan s line one of the most important contributions of this study is the proof that the acadian orogeny has affected the successor basin of the taconian orogeny in the st lawrence lowlands the thermal effect of the mid cretaceous intrusion of the monteregian hills on their country rocks is limited to one diameter or less of the intrusive body as shown by the narrow

thermal maturity of lower paleozoic sedimentary successions in arctic canada mean maximum graptolite reflectance values from numerous sections in arctic canada range from 0 6 in cornwallis island and northwestern devon island to 4 7 in ellesmere island we attribute this great lateral reflectance variation to differing burial depths of the graptolite bearing strata beneath thick synorogenic siliciclastic covers we attribute the low maturity of rocks in northern cornwallis and eastern bathurst islands to a maximum burial of about 2 km elsewhere we used the paleogeographic location and proximity to the ellesmerian overthrust wedge to interpret the measured reflectance values in northern ellesmere island where the highest graptolite reflectance values 4 7 occur as much as 9 6 km of synorogenic siliciclastics accumulated on a tectonically loaded carbonate shelf initial synorogenic siliciclastics encountered substantial submarine to basin relief and thus about 2 km of sediment were deposited prior to the initiation of deposition on the adjacent drowned shelf also the deep water sequence probably was underlain by attenuated continental crust adjacent to the southeastward advancing ellesmerian overthrust wedge together these factors caused deposition of as much as 7 6 km of sediment in western melville island and as much as 9 6 km in northeastern ellesmere island on the drowned shelf synorogenic stratal thicknesses were less a feature we attribu e to a thicker more rigid crustal sequence and greater distance from the ellesmerian tectonic loading we expect liquid hydrocarbons to be generated from the organic matter in the shales in areas with a graptolite r0 maximum gr0 max of less than 1 7 the presence of two types of solid bitumens having different reflectances morphologies and optical textures suggests that hydrocarbons were generated and migrated through the graptolite bearing strata we expect only gaseous hydrocarbons in areas where gr0 max exceeds 2 0 r0

anisotropic fragments in strongly folded and faulted coals from the rocky mountain area of southeast british columbia the mammoth coal seam in southeastern british columbia canada was structurally thickened to 100 m as a result of laramide folding and faulting samples from the coal seam examined using reflected light microscopy include thermally altered coal macerals their by products e g pyrolytic carbon and in addition heat affected preoxidized coke the heat affected residues are composed of material formed by friction produced from faulting of the coal bearing strata the pyrolytic carbon was formed from the distillation of coal and from coal tar pitch the occurrence of preoxidized heat affected vitrinite suggests that the mammoth coal seam was oxidized before faulting

use of the geotechnical centrifuge as a tool to model dense nonaqueous phase liquid migration in fractures 1 we describe a study undertaken to investigate the potential of the geotechnical centrifuge as an experimental tool to study dense nonaqueous phase liquid dnapl behavior in fracture systems scaling laws are developed that link observations made in a centrifuge model of a fracture system to the full scale problem prototype centrifuge experiments carried out in synthetic fractures described by smooth walled vertical capillary tubes demonstrate for the first time that the geotechnical centrifuge can be used to model dnapl transport in a simplified system provided that inertial forces are negligible in both the model and the prototype experiments also confirm as predicted by kueper and mcwhorter 1991 that dnapl invades a smooth walled vertical fracture when the dnapl pool height at its entrance reaches its entry pressure a simple mathematical model describing the displacement of the dnapl water interface is also presented the predictions of this model and the experimental data are in good agreement with each other in the lower half of an invaded fracture however at the early stages of dnapl invasion into the fracture our observed dnapl water interface velocities are slower than predicted by the model we attribute this to an apparent dependence of the local capillary pressure on the interface displacement velocity

scaling unstable infiltration in the vadose zone this technical note examines the feasibility of physically modelling unstable water flow in the form of fingers in the vadose zone a scaling analysis is performed based on published expressions for the width and velocity of fingers as well as the distance between fingers particular reference is given to the use of a geotechnical centrifuge as an experimental apparatus for modelling this phenomenon initial results are presented for 1g and 10g fingers from a preliminary experimental program undertaken to explore the analysis these results agree with the scaling analysis presented and indicate that finger scaling using centrifugal modelling techniques is possible

lateral expansion of preferential flow paths in sands the stability and persistence of preferential flow paths in sands can determine the flow paths of subsequent infiltration events we have measured the evolution of preferential flow paths in a slab of sandy soil using an array of tensiometers and light transmission the pressure and water content measurements show that the nonuniform moisture content exists even when the potentials are equalized horizontally and that then are the result of hysteresis in the soil s pressure saturation relationship the equalization of potential takes place over several days if at all and is consistent initially with estimates of vapor transport out of the finger cores once the soil is wet enough the remainder of water movement takes place in liquid films hysteresis produces another interesting situation when the pack is drained we find that the wetter portions of the soil can be at a lower potential than the drier portions resulting in a horizontal driving force for a flow of water from the drier to the wetter soil

petroleum source rock potential of the silurian dadas shales in the hazro and korudag regions of southeast anatolia turkey abstract shales of the silurian dadas formation exposed in the southeast anatolia were investigated by organic geochemical methods the toc contents range from 0 24 to 1 48 wt for the hazro samples and 0 19 to 3 58 wt for the korudag samples tmax values between 438 and 440 c in the hazro samples indicate thermal maturity tmax values ranging from 456 to 541 c in the korudag samples indicate late to over maturity based on the calculated vitrinite reflectance and measured vitrinite equivalent reflectance values the korudag samples have a maximum of 1 91 r g v in the gas generation window while a maximum value of 0 79 r amor v of one sample from the hazro section is in the oil generation window illite crystallinity ic values of all samples are consistent with maturity results pr ph ratios ranging from 1 32 to 2 28 and c29 c30 hopane ratios 1 0 indicate an anoxic to sub oxic marine carbonate depositional environment the hazro shales do not have any shale oil or shale gas potential because of their low oil saturation index values and early to moderate thermal maturation at first glance the korudag shales can be considered a shale gas formation because of their organic richness thickness and thermal over maturity however the low silica content and brittle index values of these shales are preventing their suitability as shale gas resource systems

effects of nanoporosity and surface imperfections on solid bitumen reflectance bro measurements in unconventional reservoirs abstract bitumen reflectance bro is an alternative maturity indicator to vitrinite reflectance vro in lower paleozoic and marine rocks where few higher plant macerals can be found in unconventional petroleum rocks locally exuded and or migrated oil are retained in the tight rocks and thermally and diagenetically consolidated into solid bitumen and pyrobitumen finding suitable bitumen macerals for bro measurements pose a challenge in indicating the proper thermal maturity this study reports the effects of surface imperfections caused by nanoporosity surface granularities and impurities on measuring bro in core samples from the jurassic nordegg shale shale oil and the triassic montney siltstone tight gas in the western canada sedimentary basin the degree that bitumen s surface imperfections influence any given reflectance measurement was controlled by changing the probe size area the larger the measuring probe the higher the degree of surface imperfections is included in bro readings the effect is quantified in this paper showing up to 27 diminishment of mean bro values when the probe size increased from 0 31 to 5 85 m2 the mode in which bitumen accumulates within the rock has a strong influence on the degree of surface imperfections bitumen which is disseminated within clay matrix introduces a high degree of nanoporosity and mineral interference and hence will result in lowest bro in contrast inclusions of high reflecting micrinite or diagenetic minerals such as pyrite result in higher bro these effects can vary at the microscopic scale leading to multiple populations of reflectance readings and difficult interpretations of thermal maturity

correlations among the reflectances of vitrinite chitinozoans graptolites and scolecodonts abstract paleozoic marine sequences sampled in outcrops and wells of northeastern gaspe peninsula quebec appalachians yield kerogen composed in part of vitrinite and zooclasts chitinozoans scolecodonts and graptolites on which reflectance measurements were made the comparison between means of random measurements show that reflectance of chitinozoans is similar to that of telinite vitrinite with a cellular texture and that the reflectance of scolecodonts is significantly lower than that of telinite in the lower range of studied values at higher reflectivities differences decrease but at the end of the condensate gas zone reflectancea are not yet identical as shown by previous studies reflectance of graptolites is slightly less than that of telinite pyrobitumen reflectance is related to the lithology of the host rock and no generalized correlation can be established between the reflectance of pyrobitumen and that of vitrinite

dispersed organic matter from silurian shales of the barrandian basin czech republic optical properties chemical composition and thermal maturity abstract samples of lower silurian liten and kopanina formations dark shales from the barrandian basin czech republic were examined using reflected light microscopy fourier transform infrared spectroscopy ft ir and gas chromatography mass spectrometry gc ms the samples contained uniform assemblage of organic material that included dominant graptolites chitinozoa bitumens and minor anthracite to meta anthracite rank particle of unknown origin two types of graptolite morphologies were recognized a nongranular blocky type and a granular type bitumen is also common in these rocks and forms discrete oval bodies resembling droplets or angular particles with granular internal fabrics the thermal maturity of the sediments was examined by measuring random reflectance of organic particles the variations in graptolite reflectance in between three localities in the western part of the basin were relatively minor suggesting a similar level of diagenetic transformation the values range from 0 78 to 1 53 rr the reflectance of graptolites was correlated with the reflectance of chitinozoa and bitumen and also indirectly with illite crystallinity data which indicates thermal maturation levels in the high temperature part of the oil window to the onset of wet gas condensate zone mature petroleum that commonly impregnates veins crosscutting the sequence further supports a maturation level within the oil window graptolite and bitumen reflectance values markedly elevated above the regional diagenetic background were found in several centimeter wide contact zones immediately adjacent to basalt sills that locally penetrate the silurian strata as shown by computer modeling heating in the range of 600 800 c which lasted only several years was sufficient to promote an increase in reflectance up to 2 2 5 rr in the contact samples with increasing thermal stress the graptolite periderm undergoes progressive optical and structural changes being gradually converted into a highly condensed aromatic residuum structurally and chemically similar to highly matured kerogen on a basin wide scale however the overall impact of basalt intrusions on organic maturity of enclosing shales was minimal

geochemical and petrographic characterization of the upper ordovician utica shale southern quebec canada abstract the utica shale is a potential unconventional tight gas reservoir from southern quebec the utica shale is a calcareous shale with intervals of fine grained siltstone with total organic content of 1 2 wt median n 408 the major organic matter constituents are migrabitumen and zooclasts chitinozoan and graptolite macerals the primary kerogen is characterized as marine due to the presence of chitinozoan and marine derived prasinophyte algae such as tasmanites a significant portion of the bulk organic matter is dominated by migrabitumen the present hydrocarbon potential s2 mg hc g rock of the utica shale is largely controlled by distribution of solid migrabitumen throughout the unit hydrogen index hi declines with increasing maturity which is controlled by greater burial from shallow to deep sections oxygen index oi remains low in most samples which is attributed to lack of terrestrial input however organic lean intervals show significantly inflated oi due to interference of mineral carbon possibly siderite random reflectance measurements on matrix solid bitumen and chitinozoans are robust indicators of thermal maturity the maturity ranges from the late oil window in the shallow utica to the wet and dry gas windows in the intermediate and deep utica respectively the results suggest that matrix bitumen formed during migration and dissemination of hydrocarbon into the clay fraction of the rock this is associated with significant bacterial sulfate reduction possibly in the early stages of generation and migration of oil it appears that the porous siltstone facies in the deeply buried section of the utica shale acts as a reservoir for the migrated bitumen from organic rich strata within the section and or possibly overlying source rock

graptolite reflectance in the prehnite pumpellyite zone of northern maine u s a abstract reflectance data has been collected on ordovician lower devonian graptolites from the prehnite pumpellyite metamorphic region in northeast aroostook county maine u s a at the northern end of the appalachian mountain belt the data is reported as the mean maximum reflectance which crossplots maximum and minimum reflectance vs bireflectance demonstrate is similar for samples mounted either perpendicular or parallel to bedding given a moderately sized data set 20 points like the prehnite pumpellyite subfacies graptolite reflectance increases from west 1 5 to east 5 5 and supports a post early devonian acadian age for the regional metamorphism reflectance contours show however that the area of highest metamorphism is to the east rather than the southeast where limited data suggest the level of metamorphism may actually decrease slightly illustrating the advantage of continuously increasing organic maturation indicators for outlining thermal patterns in broad areas of low grade regional metamorphism

economic coalbed methane production in the canadian foothills solving the puzzle abstract the producibility of methane at economic rates from thick and very gassy coals in the canadian foothills and mountains remains a major challenge these structurally deformed and often sheared coals are generally characterized by low permeabilities which is the main limiting factor restricting the flow of gas through natural fractures a preliminary evaluation of the cleating in the coals and of the jointing in the interburden clastics was carried out in the elkview mine of se british columbia field observations were supplemented by microscopic evidence on coal microtextures produced by shearing and their impact on coal permeability permeability of the coals tested at simulated in situ stress conditions and parallel to bedding surfaces was highly variable ranging from 2 09 md in seam 3 greenhills mine to less than 0 001 md in the sheared seam 10 elkview mine this variation may be rationalized based on variations in maceral composition stress history degree of shearing and the mode of deformation of the coal seams in these tectonically complex regions shearing gave rise to a variety of complex textures in coal such as slickensides shear cones and striated features small scale thrusts in the hangingwall and brittle and ductile microtextures furthermore the coal seams act as aquitards to the flow of water most likely because of low permeability water flow occurs at the contact between coal and interbedded coarser clastics and within the highly fractured and jointed sandstone units the cone of effective depressurization required for coal gas drainage to occur in the study area is influenced by a the development of a joint system in the more competent clastic beds that would provide the high permeability pathways for water and gas and b the ability of the rocks above the coals to re pressurize as a result of either surface recharge or water flow both laterally and vertically within the succession therefore multidisciplinary studies of hydrology coalification history and structure would help increase our understanding of the mechanisms and timing of cleat development effect of shearing on coal permeability and presence of systematic fractures in the non coaly lithologies

an integrated platform for thermal maturity assessment of polyphase long lasting sedimentary basins from classical to brand new thermal parameters and models an example from the on shore baltic basin poland abstract paleo thermometers in sedimentary basins often drive to misleading thermal modelling when applied alone or only on potentially productive paleozoic source rocks different paleo thermal and thermo chronological data have been used as constraints to model the silurian to cenozoic succession of a recently drilled well in the onshore portion of the baltic basin in northern poland this dataset provides an integrated platform for thermal maturity assessment contributing to the highly debated reconstruction of the thermal history of the baltic basin in the last decade the well stratigraphy consists of a lower paleozoic marine clayey and arenaceous calcareous succession about 1000 m thick that is unconformably overlain by a 2000 m thick permian to cenozoic sequence developed in a continental to shallow marine environment optical microscopy ft ir and raman spectroscopy analysis of organic matter have been coupled with u th he data to produce a robust vitrinite reflectance profile and constrain the 1d thermal modelling of the well in addition such a thermal maturity profile was validated by an independent thermal modelling calibrated by the smectite illitization kinetics both models identify high heat flow conditions up to 1 7 hfu at the end of mesozoic the lower paleozoic succession entered the late oil window of hc generation during this last heating event

the ordovician silurian boundary northern canadian cordillera graptolite and conodont correlation the upper ordovician graptolite facies of the northern canadian cordillera is divided into two biostratigraphic units the dicellograptus ornatus zone and the pacificograptus pacificus zone interb

coalification and graphitization of graptolites in the anchizone and lower epizone abstract in lower paleozoic sediments of the south alpine carnic alps carinthia austria fragments of graptolites were used to trace the process of coalification and graphitization in a continuous anchizonal to epizonal metamorphic section beginning with the onset of meta anthracitic coal ranks the process of graphitization produces graptolites with the structure of coke like transitional matter the path of coalification of graptolite fragments is explained by the model of a reflectance indicating surface ris this path resembles the coalification of vitrinite during the process of coalification the shape of the ris shows a non coaxial evolution starting with a primary biaxial negative geometry the oblate graptolite ris shapes of the carnic alps are indicative of a metamorphic event with only minor tectonic influence

study of a silurian sequence of dornes region central iberian zone portugal the contribution of organic petrology and palynofacies abstract a wenlock silurian sedimentary continuous sequence was sampled in the dornes region central iberian zone portugal to characterize the organic matter type using different microscopic analyses organic petrology and palynofacies total organic carbon toc was also determined samples are part of foz da serta formation and correspond to mudstone punctually with sandstone rich in organic matter mean toc value of 5 1 whole rock samples showed a dominance of non granular graptolites lath and blocky shape and solid bitumen lath shape graptolites display the characteristic segmented structure in the blocky shape graptolites the fusellar layers of the graptolite wall are well marked and are an important distinctive feature foz da serta graptolites are optically anisotropic as well as the solid bitumen non granular graptolite s maximum reflectance varies from 1 43 to 3 94 and solid bitumen maximum reflectance oscillates between 1 09 and 2 22 vitrinite reflectance equivalent was calculated using bertrand and malo s equation values between 1 97 and 3 72 denoting a post mature stage for the organic matter no relation was established with confidence between graptolite maximum reflectance and solid bitumen maximum reflectance the palynofacies study confirmed not only the presence of graptolite and solid bitumen but also amorphous material derived from graptolite under transmitted white light graptolite features were not noticed to improve the palynofacies characterization reflected white light was used on slides thus exposing distinctive graptolite features the different lights and preparation types used allowed a better characterization of the organic matter present in foz da serta formation samples mainly the graptolites the use of reflected white light in the palynofacies study proved to be extremely important in the description of the graptolite features

fingered flow in two dimensions 1 measurement of matric potential precise management of the changing matric potential during infiltration into unsaturated soil required the development of miniature high speed planar tensiometers a novel design was developed with response time of less than 1 s the applicability of the devices is shown through measurements of the matric potential in growing instabilities both in the induction zone and along the vertical finger profile tensiometry is demonstrated to be a practical method of obtaining data with high temporal and spatial resolution for the study of dynamic flow fields and facilitates testing of theoretical results for unstable flow fields

organic petrography of graptolite fragments from turkey abstract the reflectance and bireflectance of graptolite fragments silurian ordovician from southeast turkey were examined and the morphology was described using reflected light microscopy the dispersion of maximum and minimum reflectance of graptolites sectioned parallel and perpendicular to the bedding was also determined the graptolites were anisotropic and the anisotropy was stronger for sections perpendicular to the bedding the graptolite fragments show two types of surface morphology granular and non granular the granular type had a rough surface and granular anisotropy the non granular fragments showed a smooth surface and basic anisotropy the fine internal structure of graptolite was evident under crossed polars the reflectance of graptolite increased with depth and was higher than other organic material e g bitumen found in the same sediment the present study indicates that the reflectance of graptolite in sediment can be used to determine the maturity of the dediment

optical properties of scolecodonts and their use as indicators of thermal maturity abstract dispersion of reflectances in air and oil between 400 and 700 nm of a suiteof scolecodont concentrates with known conodont alteration index was determined using a reflected light microscope refractive and absorptive indices of these scolecodonts were calculated using their determined reflectances morphologically scolecodonts in carbonate show similar granular morphology to that of graptolites fine structural details of scolecodonts can be observed under reflected light reflectances refractive and absorptive indices of scolecodonts at 546 nm increase with increase of the conodont alteration index indicating that these properties of scolecodonts can be used to determine the maturity of sediments dispersion of the optical properties of scolecodonts follows similar trends to those for vitrinite natural bitumen and graptolites indicating similar molecular structural changes with increasing maturity

normalograptus kufraensis a new species of graptolite from the western margin of the kufra basin libya normalograptus kufraensis sp nov occurs as monospecific assemblages in the tanezzuft formation at the western margin of the kufra basin jabal eghei southern libya these graptolites have parallel sided rhabdosomes with long straight virgellae climacograptid thecae and a full straight median septum n kufraensis is intermediate between ordovician graptolites from the n angustus perner lineage and the younger sister species n ajjeri legrand and n arrikini legrand n kufraensis differs from these taxa as follows it is broader than n angustus it has greater thecal spacing than n ajjeri or n arrikini a table comparing measurements of n kufraensis with 44 other normalograptus taxa differentiates it from other members of this morphologically conservative group even though n angustus and n ajjeri are very long ranging graptolites a stratophenetic approach suggests that the specimens from jabal eghei may be of late hirnantian or younger age the faunal composition and preservation suggests these graptolites occupied the cratonic invader biotope the stratigraphic succession records deglacial flooding and fluctuating of redox in the tanezzuft formation with the graptolites indicating a short lived interval of anoxia

thermal maturity and burial history of paleozoic rocks in western newfoundland palynomorphs and graptolites from paleozoic strata in western newfoundland are examined and correlated with previously published data to identify fossils which are characteristic of proven and suspected source rocks measurements of colour alteration of acritarchs and spores acritarch alteration index and thermal alteration index random graptolite reflectance and vitrinite reflectance are applied to determine regional thermal maturation and burial history general trends of increasing maturity from south to north along the northen peninsula and from west to east across the port au port peninsula are observed within these general trends a more detailed distribution of thermal maturities can be recognized in the south upper ordovician rocks of the long point group western port au port peninsula exhibit the lowest maturity values found in western newfoundland and are considered immature or marginally mature middle ordovician rocks of the goose tickle and table head groups and the lower ordovician

microstructure of graptolite periderm in silurian gas shales of northern poland abstract core samples of silurian graptolite shales from an exploration borehole within the baltic basin were examined by optical microscopy raman spectroscopy and high resolution transmission electron microscopy graptolite periderm is composed of poorly ordered carbonaceous material of mainly aromatic structures the dimension of the coherent domains is 1 2 nm they are composed of two to three stacked layers raman spectral parameters of graptolite periderm are correlated with the mean random rr and mean maximum rmax reflectance of graptolites the spectral id1 ig ratio predicts thermal maturity in a mean reflectance of graptolites rr range between 1 30 and 1 80 rmax 1 40 2 00 vitrinite reflectance equivalent vre 1 10 1 50 it is possible to calculate vreraman from the id1 ig ratio

variation of graptolite reflectance with depth of burial abstract changes in reflectance and bireflectance of graptolite with increasing depths of burial were studied in four sequences of samples two from boreholes in poland and sweden and from two outcrop sections in western and northwestern canada graptolites show similar optical changes in reflectance and bireflectance with increasing depths of burial to those of vitrinite maximum reflectance of low maturity graptolites r o max 1 1 1 7 increases gradually with depth of burial at 0 14 per 100 m for the polish samples and at a similar but more variable rate at 0 12 0 43 per 100 m for the canadian samples for high maturity graptolites r o max 8 0 9 0 in the chlorite zone of metamorphism indirect correlation between the optical properties of graptolites and those of vitrinite has been established using conodont alteration indices in general graptolites show higher reflectance levels than vitrinite for the same conodont indices of thermal maturity for immature rocks r o vitrinite 0 2 0 5 cai 1 5 graptolite maximum reflectances range from 0 6 to 1 2 for the oil generation zone r o vitrinite 0 5 1 30 cai 1 5 2 5 from 1 2 to 2 2

recent advances in coalification studies and their application to geology abstract recent advances in coalification studies since 1970 are reported concerning microscopic methods causes of coalification the coalification process as such and application to geology the degree of coalification rank is mostly determined on the basis of vitrinite reflectance measured on finely dispersed material in rocks for rocks bare of vitrinite other microscopic methods are used such as fluorescence properties of liptinites and graptolite reflectance under incident light or coloration of microfossils like palynomorphs and conodonts in transmitted light the validity of the various methods is discussed maximum rock temperature and its duration are the main causes of chemical coalification reactions heating rates during subsidence influence the attainment of rank equilibrium contact metamorphic coals and natural cokes formed from bituminous coals are characterized by a relatively high reflectance and anisotropy strong frictional heat may cause local increase of rank adjacent to thrust planes graphitization is thermodynamically not possible in nature without pressure and shearing confining pressure retards the chemical coalification reactions tectonic stress especially shearing promotes the increase of maximum reflectance and of anisotropy it commonly leads to bi axial optical properties instead of the more typical uni axial negative geometry of vitrinite in undisturbed coal seams bi axial optical properties are common for vitrinite inclusions in clastic rocks on the basis of combined fluorescence microscopical and geochemical studies bituminization has been recognized as the characteristic part of coalification in the range between sub bituminous and bituminous coal it is characterized by the generation of petroleum like substances which enable the coal to soften and to agglomerate during carbonization hydrogenation properties are favoured by the bituminization process the different liptinite macerals behave differently during coalification and pass coalification jumps at different rank stages a considerable part of total inertinites is formed during early coalification brown coal to sub bituminous coal stage as rank inertinite this new knowledge appears to become important in relation to hydrocarbon exploration diagenetic methane some examples for the application of coalification studies to geology refer to vitrinite reflectance as an indicator of rock diagenesis and metamorphism palaeogeographical and structural history palaeogeothermics and hydrocarbon exploration large scale areal coalification studies in foredeeps and backdeeps of ancient and recent orogens suggest estimations of crustal thicknesses and relations to plate tectonics