classification of huminite iccp system 1994 abstract in the new classification iccp system 1994 the maceral group huminite has been revised from the previous classification iccp 1971 int handbook coal petr suppl to 2nd ed to accommodate the nomenclature to changes in the other maceral groups especially the changes in the vitrinite classification iccp 1998 the new vitrinite classification iccp system 1994 fuel 77 349 358 the vitrinite and huminite systems have been correlated so that down to the level of sub maceral groups the two systems can be used in parallel at the level of macerals and for finer classifications the analyst now has according to the nature of the coal and the purpose of the analysis a choice of using either of the two classification systems for huminite and vitrinite this is in accordance with the new iso coal classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals

a multidisciplinary study of the golbasi harmanli coal seam se turkey abstract this study focuses on the pleistocene golbasi harmanli coal deposit located in the east anatolian fault zone eafz se turkey the principal aim of the study is to determine factors that controlled peat accumulation by means of palaeontological data routine coal analyses proximate ultimate mineralogical composition based on xrd and sem edx and coal petrography the basin infillings consist of alluvial fluvial and lacustrine sediments palaeolake levels along with sedimentation were presumably controlled by the eafz during late pliocene to holocene times the investigated coal bearing zone is composed of a thick coal seam up to 39 m with thin clastic intercalations of fossiliferous claystones palaeontological data from these clastic bands imply that the coal accumulated during middle pleistocene times an uncommon period for the formation of thick coals in turkey we suggest that the movements of the eafz caused rapid subsidence and along with favourable climatic conditions allowed large peat accumulation in a relatively short period of time the results of proximate and ultimate analyses from 29 coal samples obtained from two cores show high ash yields av 32 relatively low sulphur content av 1 8 low net calorific value av 11 6 mj kg and low total carbon content av 35 5 on an air dry basis the mean random reflectances of eu ulminite b indicate a low rank coal maceral compositions and maceral indices indicate that the peat accumulated under limno telmatic mesotrophic conditions with peat forming vegetation being composed of mainly herbaceous plants ostracoda and mollusca fauna from intercalating clastic layers within the coal seam provide important information about the geographic distribution of fossil taxa environmental evaluation of the intercalations and the age of the studied coal seam the ostracoda species gomphocythere geareyi was identified within the coal seam for the first time humphcypris subterranea is the first fossil record of this ostracoda genus in turkey these along with the presence of the gastropoda subspecies bithynia phialensis syriaca imply a transport into the palaeomire via migratory birds from the eastern mediterranean areas discovery of humphcypris subterranea bithynia phialensis syriaca and the african originated genus gomphocythere in the golbasi harmanli coal deposit marks their northernmost worldwide occurrence

sedimentation in a humid interior extensional basin the cenozoic li basin northern thailand facies distributions in extensional basins are controlled by a combination of factors including local and regional tectonics climate hinterland characteristics and base level changes during the mid cenozoic northern thailand was a region in which active basin formation was occurring as a result of regional extension related to major strike slip faults it was also a time when the climate was relatively humid the li basin is one of about 40 cenozoic basins in northern thailand that have a fill of continental facies and it is also one of a number of basins that contain economic coal deposits analysis of the geographical and temporal distribution of facies in the li basin indicates that it had internal drainage fed by rivers that supplied water and sediment to extensive floodplain and lake environments variations in the sediment supply were an important control on the relative development of fluvial channel and muddy overbank facies during periods of high clastic input and peat swamp and lacustrine facies when clastic input was lower changes in palaeosol type and the occurrence of peat deposits indicate that there was a trend towards drier conditions through the period of deposition of the available sections late oligocene to miocene the li basin succession provides an example of a small 500 km 2 extensional basin formed in a humid climate with interior drainage and periods of low clastic sediment supply these conditions resulted in an association of facies deposited in permanent lakes peat swamps wet and dry floodplains fluvial channels and local alluvial fans the relationships between depositional facies and tectonic climatic and sediment supply controls established in this case study may be applicable to other rift and transtensional basins

evidence of early generation of liquid hydrocarbon from suberinite as visible under the microscope the early generation of liquid hydrocarbons from suberinite can be clearly observed under the microscope the generation of this oil like material mainly in the form of exsudatinite from the maceral suberinite occurs at a maturity level of about 0 4 vitrinite reflectance hydrocarbons appear to be naturally expelled from coal initially through sweating and agglomeration of suberinite which subsequently forms exsudatinite it is suggested that extensive expulsion of exsudatinite causes cracks to develop in vitrinite whereas limited expulsion of exsudatinite will only impregnate the vitrinite matrix if cracks are formed it is possible they could progressively develop to form an exsudatinite crack network the formation of such a network is believed to represent an effective way of hydrocarbon expulsion from coal source rocks

liptinite in coal and oil source rocks in northern thailand abstract palynological study of northern thailand coal and oil deposits indicates a similar palynological association to that of the borneo region coal petrographic studies of these deposits show variations in the liptinite macerals especially alginite types the oldest of these coal and oil deposits which are of late oligocene to early miocene age are dominated by botryococcus sp or botryococcus related algae thick walled lamaginites and spores and pollen of temperate affinity are found in some areas by contrast thin walled lamaginite is dominant in late middle miocene time resinite suberinite and cutinite are dominant in forest swamp coal deposits whereas alginite cutinite and lycopodium spores are dominant in lacustrine environments exsudatinite is common even at early levels of maturation these liptinite macerals can be major sources of oil and gas

petrological and organic geochemical investigation of recent peats with known environments of deposition abstract a series of recent peat samples from tropical sub tropical and temperate locations were investigated using coal petrographical and organic geochemical techniques maceral and biomarker compositions were examined to see if they correlated or diverged from the known environment of deposition of the peats the proportion of humotelinite was related to the water depth and the frequency of dry periods the ph and trophic level have a modifying influence on the preservation of tissues furthermore the proportions of sclerotinite in the peats seem to reflected the oxygen status in the mire which was also mirrored in the abundance of humic and fulvic acids a facies diagram was calculated for the peat samples to see how maceral indices would fare in interpreting their known environments of deposition the results proved to be generally unsuccessful as the herbaceous and woody peats did not always give the predicted high humodetrinite and humotelinite compositions respectively the aliphatic hydrocarbon fraction from the extracts of the peat samples show that mainly odd numbered n alkanes are present diterpenoids triterpenoids and hopanoids were found in most samples and were mainly unsaturated in nature the relative proportion of hopanoids in pears appears to be related to bacterial activity in acidic environments de a triterpenoids were also detected in the peat stage of diagenesis in an angiosperm dominated peat type mariscus polycyclic aromatic triterpenoids were present in the aromatic fraction of the extract their occurrence and proportion appears to be related to the degree of humification in a taxodium peat mono di and triaromatic diterpenoids were detected the presence of these aromatic biomarkers indicate the rapid formation of these compounds in the peat stage mainly mediated by microbial activity

elevated pore pressure and anomalously low stress in regions of low frequency earthquakes along the nankai trough subduction megathrust 1 recent seismic reflection and ocean bottom seismometer obs studies reveal broad regions of low seismic velocity along the nankai subduction plate boundary megathrust offshore sw japan these low velocity zones lvz s extend 55 km landward from the trench corresponding to depths of 10 km below sea floor here we estimate the in situ pore pressure and stress state within these lvz s by combining p wave velocities obtained from the geophysical surveys with new well constrained empirical relations between p wave velocity porosity and effective mean stress defined by laboratory deformation tests on drill core samples of the incoming oceanic sediment we document excess pore pressures of 17 87 mpa that extend 55 km into the subduction zone indicating that trapped pore fluids support 45 91 of the overburden stress along the base of the upper plate and surrounding major fault zones the resulting effective stresses in the lvz are limited to 1 3 of the values expected for non overpressured conditions these low effective stresses should lead to a mechanically weak and predominantly aseismic plate boundary the region of lowest effective stress coincides with precisely located very low frequency earthquakes providing the first quantitative evidence linking these anomalous slip events to low stress and high pore pressure

utility of coal petrology for sequence stratigraphic analysis abstract sequence stratigraphy seeks to predict the depositional architecture of sediments based on the principle that their superposition and lateral arrangement are largely determined by the rate at which accommodation is made below depositional base level relative to the supply rate of sediments depositional base level is generally correlated with sea level which in paralic peat coal deposits controls the position of the groundwater table above which oxidation ablation and erosion would occur the current late quaternary sequence is used to discuss some of the constraints on coal formation that stem from the interaction of short and long period modulations on sequence forming eustatic cycles the results show that the mid transgressive systems tract is unlikely to produce significant coal deposits which is supported by a survey of the relevant literature from eight different countries it reveals a bimodal distribution of coal deposits with the strongest mode being situated in the early transgressive systems tract while a broader secondary mode occurs in the early and mid highstand position this concentration contrasts with the complete absence of any significant coal deposits in the early and mid lowstand systems tract and only a low occupancy of the late highstand systems tracts the reasons for this distribution are briefly discussed and attention is drawn to the possible over stating of the coal forming potential of the late lowstand systems tract following a brief discussion of the sequence stratigraphic interpretation of coal measures emphasis is put on the application of sequence stratigraphy to the study of coal seams and their composition at various levels of petrographic detail while in low rank coals botanical affinities contribute much to the lithotype based analysis a genetic assessment of bituminous coal seams relies primarily on physical and chemical palaeo environmental signatures simple properties such as maximum coal thickness low detrital mineral content and maximum preservation of vitrinite particularly of telovitrinite define a good balance between the former rates of accommodation versus peat accumulation iso metamorphic variations in telovitrinite reflectance and its dispersion measured by the coefficient of variation have also contributed to the palaeo environmental interpretation this paper confirms the identification within coal seams of most of the sequence stratigraphically significant surfaces e g sequence and parasequence boundaries transgressive flooding and maximum flooding surfaces it also gives examples of some new ones referred to as accommodation reversal non marine flooding give up transgressive terrestrialisation and paludification surfaces some of these are specific to coal measures but the give up transgressive and accommodation reversal surfaces may have wider significance

coal maceral ratios as indicators of environment of deposition do they work for ombrogenous mires an example from the miocene of new zealand abstract maceral indices were applied to sub bituminous coals of the maryville coal measures as a means of interpreting environment of deposition very low amounts of inertinite and ubiquitous bituminite lead to difficulties in interpretation of the maceral ratios comparison with modern analogues suggests the theoretical basis for discrimination of mire type by maceral ratios is not well founded on the following grounds absence of well structured wood tissues does not imply the absence of arborescent vegetation inertinite formation may be unrelated to vegetation gelification is used in a geochemical sense and does not indicate groundwater table level as supposed for biochemical gelification detrital macerals often result from in situ fragmentation and not transportation

oil shale sedimentology and geochemistry in cenozoic mae sot basin thailand the intermontane mae sot basin thailand contains carbonate rich oil shales in which oil yield mineralogy and major and trace element geochemistry are related to the rock type higher grade oil shale is significantly enriched in silicate minerals quartz feldspars clays and analcite relative to carbonates and in dolomite relative to calcite couplets of organic rich and mineral rich laminae increase in mean thickness from 0 080 mm to 0 670 mm from high to low grade oil shale the organic material consists mainly of lamalginite and yields up to 341 l of oil mt 81 8 gal ton on retorting fish and vascular plant fragments are the main megafossils mappable oil shale sequences 10 m 33 ft thick are interstratified with marlstone sandstone sequences 70 m 230 ft thick markov chain analysis applied to stratigraphic sequences indicates that low grade oil shale passes gradually into high grade oil shale and vice versa the strata are interpreted as the deposits of extensive fresh to brackish lakes with oil shale sequences formed in perennial stratified lakes and marlstone sandstone sequences formed in shallow perennial lakes and subaerially exposed flats dolomite in the oil shales was authigenic the systematic changes in mineralogy and geochemistry between rock types probably reflect a gradient in redox potential from the center to the margins of the lake sandstone and siltstone beds and some carbonate laminae are interpret d as density flow deposits and form a significant proportion of the sequences the episodic deposition of oil shales reflects changes in lake level within the enclosed basin probably due to climatic fluctuations on a 24 000 to 46 000 year scale

india national gas hydrate program expedition 02 operational and technical summary abstract the india national gas hydrate program is being steered by the government of india s ministry of petroleum and natural gas mopng with participation of directorate general of hydrocarbons dgh oil and natural gas corporation limited ongc and the national oil companies and research institutes of india the india national gas hydrate program expedition 01 nghp 01 established the presence of gas hydrate in the krishna godavari kg and mahanadi basins and in the offshore area of the andaman sea basin however the gas hydrates discovered during nghp 01 were mainly distributed as fracture filling material in fine grained clay rich sediments the india national gas hydrate program expedition 02 nghp 02 was carried out with an objective to discover gas hydrate in sand rich sediment along the eastern offshore margin of india ongc planned and executed nghp 02 on the behalf of the mopng nghp 02 started on march 3 2015 and was completed on july 28 2015 total 147 days using the japanese scientific drilling vessel chikyu d v chikyu during nghp 02 42 holes at 25 sites were drilled cored and or surveyed with downhole logging tools these sites were located in four areas along the eastern margin of india and formally named area a mahanadi basin three sites area b northern part of the kg basin twelve sites area c central part of the kg basin six sites and area e southern part to the kg basin four sites all 25 sites established during nghp 02 were first drilled and logged with logging while drilling lwd tools and an additional 17 holes were then drilled and or cored with conventional coring tools hpcs escs or pressure coring tools pctb wireline logging was conducted in 10 holes and formation tests using a dual packer modular formation dynamics tester mdt tool were carried out in two holes the onboard science team used the laboratory facilities on the d v chikyu to examine and analyse the physical properties geochemistry and sedimentology of all the cores collected during the expedition core samples were also analysed in additional post expedition shore based studies conducted in numerous domestic and international gas hydrate research laboratories the nghp 02 sediment cores were archived at the national gas hydrate core repository in mumbai india which is associated with the ongc gas hydrate research and technology centre ghrtc the necessary data for characterizing the occurrence of gas hydrate such as interstitial water chlorinities core derived gas chemistry physical and sedimentological properties thermal images of the recovered cores pressure core and downhole measured logging data lwd and or conventional wireline log data were obtained from most of the drill sites established during nghp 02 almost all the drill sites yielded evidence for the occurrence of gas hydrate however the inferred in situ concentration of gas hydrate varied substantially from site to site for the most part the interpretation of downhole logging data core thermal images interstitial water analyses and pressure core images from the sites established during nghp 02 indicate that the occurrence of concentrated gas hydrate is mostly associated with coarser grained sand rich sediments this paper presents the operational and technical summary of nghp 02

oil shale and coal in intermontane basins of thailand the mae tip intermontane basin contains cenozoic oil shales in beds up to 1 m 3 3 ft thick interbedded with coal and mudstone the oil shales contain lamosite type alginite and give a maximum oil yield of 122 l mt 29 3 gal ton the beds are laterally continuous for at least 1 5 km 1 0 mi but pass into mudstones toward the basin margin the oil shales originated when peat swamps close to a steep basin margin were flooded by shallow lakes allowing algae to replace rooted vegetation this distinctive oil shale coal assemblage is known from many small intermontane basins in thailand where locally high geothermal gradients suggest potential for hydrocarbons

a self consistent mechanism for slow dynamic deformation and tsunami generation for earthquakes in the shallow subduction zone 1 dynamic pore pressure changes in the overriding wedge above a shallow dipping plate interface significantly affect the rupture dynamics of shallow subduction zone earthquakes and their tsunamigenesis for a wedge on the verge of coulomb failure everywhere including the basal fault the dynamic pore pressure increase due to up dip rupture propagation leads to widespread yielding within the wedge which is greatly enhanced by the shallow dip of the fault the widespread yielding reduces the stress drop slip velocity slip and rupture velocity giving rise to prolonged rupture duration thus explaining many anomalous features of shallow subduction zone earthquakes significant inelastic seafloor uplift occurs in the case of a shallow fault dip with the largest uplift located landward from the trench integrating this physical mechanism with existing seismic geodetic and tsunami observations can provide new insights into earthquake dynamics and deformation processes in shallow subduction zones

petrographical and organic geochemical study of the kovin lignite deposit serbia abstract the origin of the organic matter om and the characteristics of the depositional environment of lignites from the upper miocene kovin deposit hosting three coal seams of serbia were evaluated based on petrographic data bulk organic geochemical parameters biomarker analysis and stable isotope geochemistry 13c of individual biomarkers samples were collected from four boreholes gd 601 and gd 603 the a field and kb 79 and kb 91 the b field representing different parts of coal seams i ii and iii investigated lignites are typical humic coals the om of lignites is derived from woody vegetation and herbaceous peat forming plants with prevalence of the former in most samples peat forming vegetation is characterized by abundant decay resistant gymnosperm coniferous plants followed by a low amount of angiosperms lignite forming plants mostly belonged to the gymnosperm families cupressaceae taxodiaceae phyllocladaceae and pinaceae slight input of ferns fungi and aquatic macrophyta to lignite om is also evident distributions of hopanoids and isotopic compositions of these biomarkers reflect the activity of various microbial populations represented by methanotrophic chemoautotrophic and heterotrophic bacteria during diagenesis prominent c28 28 30 bisnorneohop 13 18 ene was observed for the first time in the lignite extracts according to the 13c value it was probably derived from chemoautotrophic bacteria c28 28 30 bisnorneohop 13 18 ene could be one of the possible precursors of a series of orphan aromatic hopanoids bearing an ethyl group at c 21 via progressive aromatization peatification proceeded in a fresh water environment under variable redox conditions from anoxic to slightly oxic all three coal seams are heterogeneous the lower parts of the coal seams represent a topogenous fresh water peat mire with open water areas which was subjected to inundations the upper parts of coal seams represent a wet forest swamp with relatively stable conditions despite the observed variations in all three coal seams the mean values of petrographic and organic geochemical parameters suggest general increasing of wetness and establishment of more stable conditions from seam iii to seam i maceral and biomarker data indicate that rapid flooding of the bogs stopped peat growth in all three coal seams relatively frequent variations in all three coal seams followed by repetition of lignite characteristics depict well the pronounced seasonality e g short term cycles of the climate during late miocene in investigated area

using natural maturation series to evaluate the utility of parallel reaction kinetics models an investigation of toarcian shales and carboniferous coals germany abstract open system pyrolysis is routinely performed on immature samples in order to determine the kinetic parameters of petroleum generation at both bulk and molecular levels this study tested such predictions for type ii and type iii organic matter by making calibrations with both artificial and natural maturity sequences of toarcian shales posidonia shale 0 48 1 44 rr and carboniferous vitrains 0 74 2 81 rr both natural series showed little or no compositional variability attributable to kerogen type artificially matured samples were prepared by non isothermal heating 0 7 k min of the least mature samples up to end temperatures between 375 and 470 c under either closed or open system conditions measured generation rate versus temperature curves were analyzed assuming a distributed system of activation energies and a single frequency factor in each case the resulting kinetic parameters were then used to assess bulk petroleum formation rates for geological heating conditions in the case of all artificially matured samples measured and predicted bulk petroleum formation rate vs temperature curves for each maturation stage remain within the original envelope defined by the least mature sample despite an upward shift of tmax temperatures this confirms that the reactions taking place during both the pyrolysis measurements and simulated maturation processes are the same involving mainly homolytic cracking a similar pattern of measured and predicted rate curves is reproduced by the natural maturation sequence of the toarcian shales in the maturity range of 0 53 to 1 44 rr suggesting that petroleum generation within these natural systems also results from cracking reactions and therefore that petroleum generation over geological time can be reliably extrapolated from open system pyrolysis of the appropriate immature sample by contrast significant deviations are observed for the natural coal series with measured and predicted rate curves extending beyond the immature envelopes in accordance with the pronounced increase of frequency factors and of protonated aromatic carbon concentrations this behavior is attributed to solid state aromatization reactions which compete with product generation during natural coalification but which are not reproducible to the same extent by experimental heating it is concluded that petroleum generation from vitrinitic coals over geological time cannot be reliably extrapolated from open system pyrolysis of low rank samples

equivalent formation strength as a proxy tool for exploring for the location and distribution of gas hydrates abstract gas hydrate bearing layers are normally identified by a seismic imaged bottom simulating reflectors bsr or by downhole log responses because of their high acoustic velocity and electric resistivity compared to surrounding formations these gas hydrate characteristics can also result in contrasting in situ formation compressive strengths here we describe gas hydrate bearing layers based on equivalent strength est which relates to in situ compressive strength in five exploration boreholes drilled during the indian national gas hydrate program expedition 02 nghp 02 for site nghp 02 23 a representative site for those that were established during nghp 02 the est evaluated from drilling parameters shows a constant trend of 2 mpa with some strong peak values in the 0 271 4 m below seafloor mbsf interval and a sudden increase up to 4 mpa above the bsr depth 271 4 290 0 mbsf below the bsr the est stays at 2 mpa to the bottom of the hole 378 mbsf comparing the est with logging data and a core sample description suggests that the est depth profiles reflect the formation lithology and gas hydrate content the est increases in sand rich and gas hydrate bearing zone in the lower gas hydrate layers in particular the est curve shows the same approximate trend with that of p wave velocity and resistivity measured during downhole logging similar relationships between est hydrate layer and log responses are confirmed in other four sites drilled nearby in nghp 02 area b these results suggest that the est as a proxy for in situ formation strength can indicate the location and extent of the gas hydrate as well as borehole logging although the est was calculated after drilling utilizing the recorded surface drilling parameters weight on bit top drive torque rpm and rate of penetration in this study the est can be acquired during drilling using real time drilling parameters in addition the est only requires drilling performance data without any additional tools or measurements making it a simple and economical tool for the exploration of gas hydrates

the petrology of greek brown coals abstract results are given in the petrography of greek coals collected from most of the major coal bearing basins in greece rank was determined by measuring reflectances on the maceral varieties eu ulminite a and eu ulminite b and on the maceral textinite reflectances obtained from these components indicate a coalification stage of brown coal for all samples within this group of samples there is however a fairly wide scatter of reflectance values indicating for some of them the transition zone from peat to brown coal and for others a coalification stage close to the transition into bituminous coals reflectances obtained from eu ulminite a and eu ulminite b were found to correlate well with chemical rank parameters such as volatile matter and calorific value composition was determined by maceral analysis the coals are in general characterized by low amounts of macerals of the inertinite group low to intermediate amounts of macerals of the liptinite group and high amounts of macerals of the huminite group within the latter group densinite attrinite eu ulminite and textinite make up the bulk of the samples typical macerals observed in the coals are illustrated by two black and white and three colour plates cluster analysis based on maceral distribution mineral matter and reflectance indicates that the samples studied can be divided into three major groups the first one is dominated by eu ulminite and densinite with relatively high reflectances the second is dominated by attrinite textinite and texto ulminite with somewhat lower reflectances the third is represented by a single sample in which textinite and resinite are the most abundant macerals this sample also has the lowest reflectance

guidelines for assessing the petroleum potential of coaly source rocks using rock eval pyrolysis abstract coaly source rocks are sufficiently different from marine and lacustrine source rocks in their organic matter characteristics to warrant separate guidelines for their assessment using rock eval pyrolysis the rank threshold for oil generation is indicated by the increase in bi s1 toc at rank sr 9 10 tmax 420 430 c ro 0 55 0 6 and the threshold for oil expulsion is indicated by the peak in qi s1 s2 toc at rank sr 11 12 5 tmax 430 440 c ro 0 65 0 85 the pronounced rank related increase in hi s2 toc prior to oil expulsion renders the use of immature samples inappropriate for source rock characterisation a more realistic indication of the petroleum generative potential and oil expulsion efficiency of coaly source rocks can be gained from samples near the onset of expulsion alternatively effective hi values i e his near the onset of expulsion can be estimated by translating the measured his of immature samples along the maturation pathway defined by the new zealand or other defined coal band coaly source rocks comprise a continuum of coaly lithologies including coals shaly coals and coaly mudstones determination of the total genetic potential of coaly source rock sequences is best made using lithology based samples near the onset of expulsion

physical properties and rock physics models of sediment containing natural and laboratory formed methane gas hydrate this paper presents results of shear strength and acoustic velocity p wave measurements performed on 1 samples containing natural gas hydrate from the mallik 2l 38 well mackenzie delta northwest territories 2 reconstituted ottawa sand samples containing methane gas hydrate formed in the laboratory and 3 ice bearing sands these measurements show that hydrate increases shear strength and p wave velocity in natural and reconstituted samples the proportion of this increase depends on 1 the amount and distribution of hydrate present 2 differences in sediment properties and 3 differences in test conditions stress strain curves from the mallik samples suggest that natural gas hydrate does not cement sediment grains however stress strain curves from the ottawa sand containing laboratory formed gas hydrate do imply cementation is present acoustically rock physics modeling shows that gas hydrate does not cement grains of natural mackenzie delta sediment natural gas hydrates are best modeled as part of the sediment frame this finding is in contrast with direct observations and results of ottawa sand containing laboratory formed hydrate which was found to cement grains waite et al 2004 it therefore appears that the microscopic distribution of gas hydrates in sediment and hence the effect of gas hydrate on sediment physical properties differs between natural deposits and laboratory formed samples this difference may possibly be caused by the location of water molecules that are available to form hydrate models that use laboratory derived properties to predict behavior of natural gas hydrate must account for these differences

mineralogy petrography and organic geochemistry of miocene coal seams in the kinik coalfield soma basin western turkey insights into depositional environment and palaeovegetation abstract the kinik coalfield is located in the south westernmost part of the soma basin in western turkey and hosts all three miocene coal seams from bottom to top km2 km3 and kp1 this study presents the coal petrographical mineralogical and organic geochemical features of samples collected from two deep cores samples from seam km2 generally display low ash yields and high toc content whereas the km3 and kp1 seams are characterized by relatively high ash yields and low toc values furthermore total s content of the kp1 is very high up to 7 0 on dry basis the maceral composition the coal facies diagrams and the distributions of n alkanes and diterpenoids indicate changes of depositional conditions and vegetation in the palaeomires of the km2 seam during early miocene the precursor peat of km2 seam started accumulating under limnotelmatic conditions followed by pure telmatic ones consequently initial mixed vegetation was replaced by a conifer dominant assemblage in the palaeomires in the upper parts of the km2 seam the coal facies indices and high concentrations of n alkanes along with the relatively low di di tri terpenoid ratios are indicators of the higher contribution of herbaceous species and minor abundance of conifers in the palaeomires of km3 and kp1 seams nevertheless the mineralogical composition of the km3 and kp1 seams indicate increased clastic input and alkalinity in the palaeomires that could reduce preservation of organic matter thus high ash yields and low toc were obtained from these seams in addition sulphate rich water supply along with synchronous pyroclastic air borne input into the palaeomires caused elevated total s content of the kp1 seam

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

comparison of three series of organic matter of continental origin abstract three series of sediments containing land plant derived organic matter were studied they include wells from mahakam delta indonesia miocene douala basin cameroon upper cretaceous and eastern paris basin france paleozoic all of the kerogens and coals isolated from these series can be related to type iii in a van krevelen diagram however they obviously differ in terms of chemical structure as reflected by their pyrolysis gc patterns and by their bitumen composition these observations indicate the variations in the nature of land plant derived sedimentary organic matter and thus differences in quantity and composition of the hydrocarbons which are are released upon maturation based on hydrocarbons potential of the insoluble organic matter and on pyrolysis gc there is no reason to disregard coals and to favor shales as potential source rocks in these two deltaic sequences moreover we assume that the bitumen depletion in coal samples is a reflection of loss by migration which is favored in coals when compared to shales the gc patterns of the residual saturates compared to the pyrolysis gc patterns of the related insoluble coals suggest that migration of hydrocarbons proceeds in these coals without any significant alteration of their distribution at least in the c15 range

sulfur in the changuinola peat deposit panama as an indicator of d the environments of deposition of peat and coal abstract the sulfur s content of coal is often used to infer aspects of paleoclimate trophic state and proximity to marine influence of the mire in which it was deposited in this study the s content of peat in a large back barrier mire complex on the caribbean coast of panama is related to climatic biological and tectonic factors of the depositional environment earthquake generated subsidence is greatest to the southeast leading to drowning of the deposit beneath almirante bay and 40 of the peat is now below sea level coastal mangrove peats with moderately high s content 1 5 wt s and high salinity 1 0 wt dominate the eastern margin and extend beneath the salt water and shallow marine sediments of the adjoining bay marine influence extends only a short distance onsho e except in the vicinity of brackish blackwater creeks that drain the swamp peats associated with these tidal channels are low in salinity 1 0 wt and very high in s 5 to 14 wt s apparently the result of a biogeochemical chain of s reactions leading to the concentration of c s sulfides the western part of the deposit is domed and the vegetation and the peat are concentrically zoned stunted sawgrass dominated vegetation that produces fibric very low s 0 25 wt s peat occupies the central bog plain around the bog plain mixed forest and palm forest swamps produce dense hemic and fine heroic peat with higher s content 0 250 5 wt s the s content is in proportion to the degree of humification of the peat and both are independent of the ph of the groundwater the distribution of forms of organic and inorganic sulfur in the tropical peats are found to be comparable to published values for temperate and subtropical peats despite differences in vegetation and climate the distribution of high sulfur peats in the eastern part of the deposit and low sulfur peats in the western part and the se nw transgression parallel to the trend of the coastline reflects the regional structural trend of coseismic subsidence greatest to the southeast

sequence stratigraphic analysis and the origins of tertiary brown coal lithotypes latrobe valley gippsland basin australia abstract the methods of sequence analysis have been applied to the onshore gippsland basin and in particular to the latrobe valley group coal measures which include up to five coal seams each exceeding 100 m in thickness the methods appear to provide new depositional concepts to the evolution of these seams and the development of coal lithotypes in the eastern half of the latrobe valley evidence for marine transgressions into the coal measures are recorded in most of the interseam sediment splits by the presence of contained foraminifera and dinoflagellates to the west inland these splits pinch out into continuous coal however they can be followed westwards as enhanced organic sulphur levels along sharply defined boundaries between light coal lithotypes below and dark coal lithotypes above the dark lithotype immediately overlying each of these boundaries contains the highest sulphur value and warmer climate pollen assemblages sluiter et al 1995 this volume colorimeter and lithotype logging strongly supports an upwards lightening cyclicity to coal colour at 12 20 m intervals through the approx 100 m thick seams with cycle boundaries defined at sharp planar to undulating surfaces the lightening upward lithotype cycles together with their unique boundary conditions i e enhanced organic sulphur levels warm climatic indicators and laterally equivalent marine clay splits are interpreted as parasequences and parasequence boundaries respectively each major coal seam can comprise up to five parasequences and is interpreted to represent deposition during an outbuilding high stand systems tract at one of several maximum periods of tertiary coastal onlap the top of each major seam shows evidence of truncation erosion on a regional scale and these surfaces are interpreted to represent the sequence boundaries the major seams are usually conformably underlain by marine clays and extensive aquifer sands being deposits of the late transgressive systems tracts the low stands and early parts of the transgressive systems tracts appear not to be represented in the latrobe valley due to its more basin margin location but are probably present down dip in the equivalent marine facies of the seaspray group stratigraphic correlation of the sequence boundaries identified in the coal measures to the adjacent internationally dated marine seaspray group provides a basis for chronostratigraphic correlation of the coal successions to the coastal onlap charts of haq et al exon mesozoic cenozoic chronostratigraphic chart version january 1988 and august 1989 from this dating it appears that each major seam is confined to high stands of third order eustatic cycles it therefore follows that the lithotype cycles parasequences that comprise each seam are related to fourth order eustatic cycles by analogy all the coal cycles may have developed under subtropical conditions as ombrogenous forested peat swamps in a similar manner to the holocene though tropical swamps of indonesia

hydrate morphology physical properties of sands with patchy hydrate saturation 1 the physical properties of gas hydrate bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase the host sediment grain size and the state of effective stress determine the hydrate morphology in sediments this information can be used to significantly constrain estimates of the physical properties of hydrate bearing sediments including the coarse grained sands subjected to high effective stress that are of interest as potential energy resources reported data and physical analyses suggest hydrate bearing sands contain a heterogeneous patchy hydrate distribution whereby zones with 100 pore space hydrate saturation are embedded in hydrate free sand accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate bearing sands and captures observed physical property dependencies on hydrate saturation for example numerical modeling results of sands with patchy saturation agree with experimental observation showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations the hydrate patch size itself impacts the physical properties of hydrate bearing sediments for example at constant hydrate saturation we find that conductivity electrical hydraulic and thermal increases as the number of hydrate saturated patches increases this increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross section of the specimen

the kinetics of thermal degradation of individual oil generating macerals calibration with microscopical fluorescence spectrometry and bulk flow pyrolysis abstract kinetic models for petroleum generation describe petroleum formation as either a discrete set of reactions or a continuous distribution of reactions the kinetic models are normally calibrated with data from laboratory experiments this paper discusses theoretical analytical and numerical problems encountered when results of laboratory experiments are extrapolated to geological conditions an alternative approach based on geologically matured samples is presented where quantitative petrological micro fluorometric and hydrogen index data are used in multiple regression analysis to estimate transformation ratios and genetic potentials of compositionally different oil generating entities in source rocks the data are further used in combination with reconstructed time temperature histories to calculate consistent kinetic parameters for the thermal degradation of individual macerals the results both for the genetic potentials and transformation ratios are within the expected range the important aspect of the analysis is that the results were obtained by expressing the transformation ratio as a function of a fluorescence maturity parameter and hence allow increased confidence in the application of fluorescence in maturity studies

productivity control on oil shale formation mae sot basin thailand abstract neogene oil shales from the freshwater lacustrine intermontane mae sot basin western thailand are examined in order to define a oil source rock potential b variations in molecular and isotopic geochemical characteristics and c the influence on source potential of organic matter productivity and preservation twelve samples spanning 7 m of section were examined using conventional isotopic molecular and organic petrographic methods of geochemical analysis temporal resolution is 2700 yr per sample because thermal maturity differences and fluid migration within the sample set are absent and organic matter type input variation is either minor or absent based on visual kerogen analysis we propose that organic matter differences among the samples are caused by variability in surface water productivity all samples are excellent potential source rocks vr 0 4 0 5 ro containing types i and ii organic matter modified van krevelen plot determination consisting of almost 100 fluorescent amorphous kerogen visual kerogen determination numerous diagnostic molecular markers and characteristics are present including perhydro carotene dammaranes norsterane s and novel distributions of tricyclic terpanes stable carbon isotope ratios of kerogens and extract fractions range over 5 and co vary with hydrogen index this covariance is attributed to temporal increases in surface water productivity leading to co2 limiting conditions and consequent increase in 13c of the organic matter in the photic zone during times of elevated productivity increased amounts of 13c enriched organic matter reached the water sediment interface thus times of greater productivity are accompanied by higher 13c and hydrogen index values with 13c related to productivity under co2 limiting conditions and hi related to the relative amount of the water column that was anoxic during deposition our findings suggest that in petroleum geochemical studies involving lacustrine source rocks 13c values must be used with caution as oil oil and oil source rock correlation parameters

biomarkers aromatic hydrocarbons and polar compounds in the neogene lignites and gangue sediments of the konin and turoszow brown coal basins poland abstract this paper presents geochemical characteristics of 35 samples of miocene lignites and gangue sediments clays sampled in the konin and turoszow brown coal basins poland lignites belonged to xylitic detro xylitic detritic and fusitic lithotypes organic geochemistry of them were investigated using such methods as rock eval pyrolysis gas chromatography mass spectrometry of separated aliphatic hydrocarbons compounds of medium polarity and methyl esters of fatty acids flash pyrolysis gc ms was applied for investigation of macromolecular organic matter of the samples reflected light microscopy was used to find maceral composition and huminite reflectance all samples organic matter show immature features well corresponding to its values of huminite reflectance 0 17 0 35 rock eval t max values were exceptionally low in all cases on average 387 c and they show high differentiation according to the lignite lithotypes with lowest values for xylites also other geochemical features of organic matter are lithotype dependant such as n alkanes and fatty acids distributions many biomarkers presence and distribution types and chemical composition of lignite macromolecular fraction it was possible to asses dominating sources of organic matter using relative concentrations of three groups of compounds with diterpene hopane and oleanane molecular structures most of miocene detritic lignites come from monocotyledonic material with some of them containing coniferal detritus like needle leaves xylitic lignites come from podocarpaceae pinaceae cupressaceae and taxodiaceae families what is indicated by diterpenoids and sesquitenoids distribution detro xylitic lignites show intermediate geochemical features between detritic and xylitic lignites

eocene krabi basin southern thailand paleontology and magnetostratigraphy we present the magnetostratigraphy of the late eocene krabi section from the krabi basin thailand the investigated section is about 105 m thick and consists of red and yellow siltstones sandstones gray claystones lignites and limestones we collected 86 samples at 43 different stratigraphic levels from the 105 m thick section the samples yielded a paleomagnetic direction and paleomagnetic analyses give favorable demagnetization behaviors two magnetic components can be isolated rock magnetic experiments show that the natural remanent magnetization generally results from the presence of titanomagnetite the first component has roughly the direction of the present day field the second component displays only reversed polarity with a mean direction declination 192 34 inclination 15 5 n 71 95 4 7 k 14 after bedding correction mammalian biostratigraphy indicates a late eocene age correlation to the geomagnetic polarity time scale relies on biostratigraphic data previously proposed for the fauna found in the same section these correlations have been achieved by comparing variations in the sedimentation rate derived from the alternative correlation the proposed correlation puts the krabi section in chron c12r or chron c13r this suggests sedimentation rates of 4 9 and 9 4 cm k y respectively this correlation suggests that the krabi section is older than 31 ma and younger than 34 ma

strength characteristics of sediments from a gas hydrate deposit in the krishna godavari basin on the eastern margin of india abstract knowledge of the strength of sediments overlying sub seafloor gas hydrate deposits is crucial for predicting borehole and seafloor stability during hydrate extraction ideally sediment strength should be determined along a continuous downhole profile from the seafloor to the hydrate reservoir but few such profiles have been obtained in this study we used cores retrieved at site nghp 02 23 in the krishna godavari basin in unconfined penetration tests on split cores and in triaxial deformation experiments on hydrate free sediment samples although penetrometer tests identified relatively low strength 70 250 kpa likely due to hydrate dissociation in the hydrate bearing interval 90 300 m below seafloor mbsf sediment strength exceeded 350 kpa in the intervals 140 170 and 250 270 mbsf each of which lies just above a zone of high gas hydrate concentration the average stress ratio of triaxial strength at 4 axial strain to effective mean stress qe 4 p of hydrate free silts was about 0 67 throughout the hole an exception to this trend was in fine sands from 280 mbsf in the deeper gas hydrate zone where the stress ratios were greater than 1 0 the stress ratios of hydrate bearing sediments in the deeper gas hydrate zone that were reported from the pressure core measurements were far greater than those of any hydrate free sediments for a given effective mean stress the high strength intervals in silty sediments we identified by the penetration tests could be associated with zones of high hydrate concentration because high strength layers in fine grained silty sediments commonly exhibit lower permeability than sandy layers potential hydrate host they may act as seals that assist the precipitation of hydrate below them

the organic geochemistry of coal from plant materials to coal coalification is a process that transforms plant remains under the influence of time temperature and possibly pressure to a black generally lustrous solid organic fossil fuel having a very complex chemistry although much has been learned in the past two centuries on coal chemistry we still have little knowledge of the way plant materials undergo these transformations the problem has been the existence of adequate characterization tools the advent of some new tools for structural elucidation of macromolecules has led to some revised thinking on coalification originally thought to be a process involving the full degradation of plant remains and subsequent reconstitution of these remains the general consensus today is that the process involves a selective preservation of certain resistant plant components followed by some minor reorganization of the biopolymers that survive the major components of plants do degrade and the resistant ones often constitute only a small fraction of the original mass of the plant materials this paper examines the most recent literature concerning coalification and focuses on the chemistry associated with coalification of certain recognizable plant remains that have been at the center of research activity for the past two decades thus we examine the recent knowledge of the chemistry of resistant biopolymers in extant and fossil wood cuticles resins spores and algae knowledge that has been assembled to establish the reaction pathways towards coal macromolecules

sequence stratigraphic distribution of coaly rocks fundamental controls and paralic examples significant volumes of terrigenous organic matter can be preserved to form coals only when and where the overall increase in accommodation approximately equals the production rate of peat accommodation is a function of subsidence and base level for mires base level is very specifically the groundwater table in paralic settings the groundwater table is strongly controlled by sea level and the precipitation evaporation ratio peat accumulates over a range of rates but always with a definite maximum rate set by original organic productivity and space available below depositional base level groundwater table below a threshold accommodation rate nonzero no continuous peats accumulate due to falling or low groundwater table sedimentary bypass and extensive erosion by fluvial channels this is typical of upper highstand lowstand fan and basal lowstand wedge systems tracts higher accommodation rates provide relatively stable conditions with rising groundwater tables mires initiate and copyright 1997 the american association of petroleum geologists all rights reserved 1manuscript received september 7 1995 revised manuscript received november 25 1996 final acceptance may 5 1997 2exxon production research company 3120 buffalo speedway houston texas 77096 3exxon production research company 3120 buffalo speedway houston texas 77096 present address conoco inc p o box 2197 houston texas 77252 we benefited from the input and assistance of many people of special assistance were the teams involved in collaborative studies with esso australia and esso malaysia p moore m sloan j emmett b burns a partridge s creaney hanif hussein r hill r lovell and m feeley we also thank the rock springs team r beauboeuf p mclaughlin w devlin a carroll y y chen g grabowski jr k miskell gerhardt m farley r webster and j schwalbach group members d curry and j yeakel were always helpful we also enjoyed and profited from many discussions of these concepts with our colleagues outside exxon c diessel r boyd k shanley b zaitlin p mccabe m hendricks a cohen and m kirschbaum we thank the reviewers of company reports whose careful comments on several generations of this work improved it s creaney m feeley j van wagoner f wehr j yeakel and a young f weber and j zullig provided extensive management support k linke translated our sketches into the fine figures herein we value all the help

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

development of cenozoic basins in thailand abstract there are over 60 cenozoic basins distributed in various parts of thailand both onshore and offshore these basins are mainly n s trending half grabens or grabens and most were initiated in the late oligocene the structural framework of the basins is generally governed by n s trending extensional faults which are spatially related to the movement of the nw se and ne sw trending strike slip faults that have been active since the oligocene the nw se faults are the principal dextral strike slip faults whereas the ne sw faults are the conjugate sinistral strike slip faults the collision of the india craton with southern asia since 40 50 ma caused clockwise rotation of southeast asia and movements on the strike slip faults with the associated development of cenozoic basins in this region four major cenozoic basins mergui pattani malay and phitsanulok contain up to 8000 m of sediments generally the cenozoic fills are continental sediments except in the mergui basin in the andaman sea where the sedimentary fill is mainly marine sediments fluviatile with occasional lacustrine deposits were prominent in the gulf of thailand and onshore basins during the oligocene to early miocene from early to middle miocene widespread perennial lake conditions were well developed in the onshore basins and in the western graben area of the gulf of thailand a change in tectonic and or climatic conditions took place in the middle to late miocene times resulting in the cessation of perennial lake conditions and development of a regional unconformity

petrology of a suite of sedimentary rocks associated with some cole bearing basins in northwestern thailand abstract a number of basins in northwestern thailand contain thick sequences of cenozoic sedimentary rocks oil shales and coals are prominent lithologies within these sequences and occur together in some basins most of the sequences are however dominated by either oil shales or coals the major oil shale deposit is in the mae sot basin but oil shales also occur in the ban huay dua mae moh ban pa ka li mae teep ban na hong and jae hom basins drilling and detailed mapping in the mae sot basin indicate thick sequences of oil shales and organic petrological studies show that they contain abundant lamalginite trace amounts of telalginite liptodetrinite bitumen resinite and huminite inertinite are also present in some of the rocks the parts of the sequences rich in authigenic minerals are in general petrographically similar to green river formation lamosites where clay silt sized epiclastics are more abundant similarities exist to australian tertiary lamosites vitrinite reflectance date from the oil shales and associated coals indicate a low level of maturity oil shales from the other basins are petrographically similar to the mae sot lamosites however some differences do exist the mae sot and other lamosites were deposited in lacustrine environments that probably had highly variable water depths

relative sea level control of deposition in the late permian newcastle coal measures of the sydney basin australia abstract accumulation of the 400 m thick late permian newcastle coal measures of the sydney basin was controlled by changes in relative sea level three 3rd order sequences which constitute the coal measures consist of 4th order depositional sequences of fluvial conglomerate coal and small paralic lacustrine deltas crevasse splays deposited on a coastal plain landward of a marine shoreline each 4th order sequence was deposited during a single 4th order relative sea level cycle following falls in relative sea level alluvial conglomerates derived from the new england orogen filled incised valleys above sequence boundaries forming lowstand systems tracts sigmoidal conglomerates with giant crossbeds were deposited as alluvial fill in compactional moats formed at the toes of abandoned paralic deltas alluvial sediments passed through the coastal plain directly to the marine shoreline causing the shoreface to prograde rising relative sea level caused siliciclastic sedimentation to wane during these hiatuses in the transgressive systems tract a rising water table stimulated peat mire growth blanketing the entire non marine area when the vertical accumulation of peat was outpaced by increasing rates of rising relative sea level transgressing lagoons interdistributary bays and lakes inundated the mires above maximum flooding surfaces continuing relative sea level rise in the highstand systems tracts caused paralic lacustrine crevasse splays crevasse subdeltas and small deltas to prograde westwards into the newcastle half graben from a volcanic source on the offshore uplift at this time of rising base levels sediments were trapped on the coastal plain while the marine shoreface was starved falling relative sea level terminated paralic lacustrine delta progradation and initiated exposure and erosion to repeat the cycle and initiate another 4th order sequence two source areas supplied sediment into the newcastle half graben an easterly source on the offshore uplift shed volcanic detritus into the newcastle coalfield via paralic lacustrine deltas and the new england orogen shed volcano lithic detritus via braided streams the supply from the new england orogen was switched on or increased by a fall in relative sea level while supply from the offshore uplift was switched off reduced or diverted and vice versa during a rise in relative sea level increasing rates of 2nd order falling relative sea level resulted in an upward change from predominantly marine shoreface and coastal plain sedimentation to predominantly fluvial sedimentation in the upper newcastle coal measures

structural evolution of the li basin northern thailand exposures in the oligocene to miocene section of coal mines in the li basin of northern thailand show a complex structural evolution the basins formed under approximately east west extension nw to north south striking normal faults are dominant with some east west normal faults also being present but much less frequently episodically compressional and or strike slip events affected the basin creating new east west to ne sw striking thrusts and folds and inverting some normal faults the latest episode of compression formed nw se to north south striking thrusts and folds cross cutting structures reactivation of structures syn sedimentary deformation and unconformites help to constrain the relative timing of structural events at least five episodes of predominantly nnw sse to ne sw oriented compression interrupted the extensional development of the basin the compression was probably related to the escape tectonics of the himalayan orogeny the episodic nature of the compression and extension is inconsistent with either simple strike slip related opening of the rift basins or simple extension the data from the li basin indicate a reappraisal of current tectonic models for the region is necessary

relative sea level changes recorded by paralic liptinite enriched coal facies cycles middle jurassic muslingebjerg formation hochstetter forland northeast greenland abstract the middle jurassic muslingebjerg formation of hochstetter forland northeast greenland consists of a succession of shallow marine sandstones encasing four coal seams formed in low lying coastal mires the seams are up to 3 45 m thick and contain coal facies cycles with high liptinite contents up to 70 vol the cycles generally start with huminite rich bright or banded coal and end with dull coal or clayey coal coaly claystone the dull coals are characterized by a high proportion of liptinite commonly resinite and often mineral matter liptodetrinite resinite and cutinite dominate the liptinite maceral group similarity in the relative proportions of the liptinite macerals in the bright and dull coals and the general association of bright coal and dull coal with a high resinite concentration suggest that the dull coals represent a residue after selective removal of ligno cellulosic tissues in the precursor peat of primarily the bright lithotype the clayey coal coaly claystone lithotypes have high contents of mineral matter and commonly contain alginite and pyrite occurrence of pyrite in levels with high diasterane c 27 c 29 ratios and sometimes also alginite in the clayey coal coaly claystone lithotypes indicates a marine influence during flooding of the mires this suggests a causal link between base level rise in the coastal mires and relative sea level rise accommodation space available for thick peat accumulations was governed by overall relative sea level rise and the dulling upward cycles record outpacing of peat accumulation due to accelerated rise in base level relative sea level the muslingebjerg formation consists of four depositional sequences beginning with a thick coal seam resting on a sequence boundary peat accumulation reflects onset of base level rise in the coastal area and the coals represent the lower part of the transgressive systems tract the overlying shoreface sandstones form the upper part of the transgressive systems tract and a progradational highstand systems tract alternatively the two lower seams in the succession may form a transgressive regressive couplet separated by a lagoonal sandstone split in this case a sequence boundary occurs at the top of the upper regressive seam the dulling upward cycles within the coal seams represent parasequences or possibly higher order sequences minimum age estimates suggest that they accumulated over 4000 11000 yr

deposition floral composition and sequence stratigraphy of uppermost triassic rhaetian coastal coals southern sweden abstract two uppermost triassic rhaetian coal beds a and b bed bjuv member southern sweden deposited at the margin of the danish basin were investigated in order to interpret the peat forming environments in a sequence stratigraphic context and to establish the peat forming vegetations of the precursor mires peat formed close to the coastline and was governed by base level watertable rise linked to relative sea level rise which is emphasized by rare occurrences of marine phytoplankton micrhystridium lunnomidinium scaniense and rhaetogonyaulax rhaetica in the b bed a maximum flooding surface mfs7 between the coal beds a and b shows that peat accumulation occurred as a coastal response to the continued transgression of the danish basin that culminated with deposition of the coal bearing bjuv member the lower b bed accumulated in a transgressive systems tract tst and the upper a bed in a highstand systems tract hst the b bed consists of coal and coaly mudstone intervals showing that peat formation repeatedly was outpaced by relative watertable rise the huminite rich coal intervals indicate peat formation under oxygen deficient stagnant water conditions where the peat accumulation rate balanced the watertable rise overall low ts values indicate a freshwater mire the base of coal bed b marks the start of a relative decrease in creation of accommodation space and the surface between the sediments and coal bed b represents a terrestrialisation surface tes the palynofloral composition suggests that the initial mire was characterised by dipterid dicksoniacean tree ferns and marattialean ground ferns and few canopy trees dominated by cupressacean taxodiacean wet loving conifers with subordinate bennettitalean and caytonialean trees the coal intervals in the b bed represent terrestrialisation situations characterised by a reduced ratio of accommodation rate peat accumulation rate the palynology of these intervals indicates establishment of canopy trees primarily cupressacean taxodiacean conifers accompanied by bennettitaleans and caytonialeans with an understory of marattialean ground ferns and rarer tree ferns flooding surfaces fs and accommodation reversal surfaces ars in the b bed reflect changes in the rate of watertable rise the coaly mudstone intervals represent paludification situations with an upward increasing ratio of accommodation rate peat accumulation rate in general the palynology of the b bed suggests a coal floral composition that was dominated by mid and upper canopy plants consisting of cupcressaceaen taxodiaceaen trees probably occupying areas with standing water while ginkgos cycads bennettiales and caytoniales and other seed ferns grew in less wet areas understory plants were less abundant whereas a ground cover of ferns mainly of the families marattiales and osmundales as well as lycophytes may have been pronounced the upper surface of the b bed is a give up transgressive surface guts above which peat accumulation was replaced by siliciclastic deposition the palynofloral composition suggests an open mire dominated by ground ferns and probable tree ferns with minor bennettitalean and caytonialean mid canopy trees and with hardly any upper canopy trees the a bed is considerably richer in inertinite compared to the b bed the palynofloral and petrographic change correlates with an increase in fire activity across the triassic jurassic boundary and deforestation of the early jurassic mires

association of oil source algae in some tertiary basins northern thailand abstract a coal petrographic study of sediments including coals oil shale and oil source rocks in the fossil fuel deposits of northern thailand revealed changes in alginite associations in the lower part of these tertiary deposits especially in the fang oilfield alginite a a botryococcus sp was the only type of alga found later the association of botryococcus braunii pila algae thick walled alginite b and temperate palynomorphs were recognized in many coalfields as well as in the middle part of the deposits in the fang basin their ages were late oligocene to early miocene in the upper part of the fossil fuel deposits alginite b is dominant in many basins together with botryococcus related taxa such as pila algae reinschia and fresh water dwelling ferns in the mae sod basins reinschia was found to be dominant in the northern part whereas lamaginite dominated in the south showing different environmental conditions in different parts of the basin during deposition these different associations indicate changes in depositional environments in northern thailand resulting from climatic and or sea level changes during tertiary time

occurrence and distribution of sulfur in peat forming environments of southern florida abstract cores and surface samples of peats from the everglades mangrove region of southern florida were analyzed for total sulfur and pyritic sulfur these values were compared with the petrographic botanical components of the peats as determined from point counts of oriented microtome sections pyrite occurs as individual euhedral crystals loosely packed framboids and lenses or crusts of minute crystals framboids and minute crystals are often associated with organic matter and sometimes with bacteria and fungi pyrite tends to selectively occur in void spaces in or between peat tissues in samples containing very small amounts of pyrite framboidal pyrite is the prevalent form marine to brackish peats contain the highest pyrite and total sulfur contents with brackish peats generally containing more pyrite than marine peats pyrite tends to be lower in all peats within 30 cm of the surface whether marine or brackish burial of freshwater peats beneath marine or brackish peats tends to increase the total sulfur and pyritic sulfur in the underlying peats burial beneath brackish water clay rich deposits such as splays tends to increase total sulfur and pyritic sulfur in the underlying deposits more than burial beneath less clay rich deposits

dynamic deformation of the accretionary prism excites very low frequency earthquakes 1 we have detected anomalous very low frequency earthquakes within the accretionary prism along the nankai trough southwestern japan centroid moment tensor inversion analysis reveals that the earthquake hypocenters are distributed at 10 km depth above the upper surface of the subducting philippine sea plate and within 50 70 km landward of the trough axis the focal mechanisms indicate reverse faulting their hypocenters are distributed beneath a deformation zone of an accretionary prism in sea floor topography these observations suggest that the occurrence of very low frequency earthquakes is related to numerous reverse fault systems within the accretionary prism and that the earthquakes reflect the dynamics of deformation within this accretionary prism

elastic properties of gas hydrate bearing sediments downhole measured compressional and shear wave velocities acquired in the mallik 2l 38 gas hydrate research well northwestern canada reveal that the dominant effect of gas hydrate on the elastic properties of gas hydrate bearing sediments is as a pore filling constituent as opposed to high elastic velocities predicted from a cementation theory whereby a small amount of gas hydrate in the pore space significantly increases the elastic velocities the velocity increase from gas hydrate saturation in the sediment pore space is small both the effective medium theory and a weighted equation predict a slight increase of velocities from gas hydrate concentration similar to the field observed velocities however the weighted equation more accurately describes the compressional and shear wave velocities of gas hydrate bearing sediments a decrease of poisson s ratio with an increase in the gas hydrate concentration is similar to a decrease of poisson s ratio with a decrease in the sediment porosity poiss

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

palaeoenvironmental reconstruction of the eastern part of the karapinar ayranci coal deposit central turkey abstract regional tectonic movements during the neogene period resulted in the development of several fault controlled basins in central anatolia many of these basins host economic coal deposits the recently discovered karapinar ayranci coal deposit is the most important one due to its large reserves c 1 8 gt and location in the vicinity of important urban areas the paper aims to reconstruct the palaeoenvironmental conditions before during and after coal formation in the eastern part of karapinar ayranci deposit by means of coal petrography and mineralogical data combined with sedimentological and palaeontological data the basinal infilling consists of mainly lacustrine fluvial and alluvial sediments the coal seams comprise several beds intercalating with claystone mudstone and marl the coal being lignite in rank displays high ash yield 36 4 wt on dry basis and high total sulphur content avg 7 7 wt on dry ash free basis facies diagrams and lithological features of the coal seams suggest that peat was accumulating under pure telmatic to limnotelmatic conditions however peat accumulation ceased several times due to a rise in water level therefore clastic e g quartz clay minerals and authigenic e g pyrite mineral contents are variable along the seam profile gastropod and ostracod fauna points to freshwater conditions in the palaeomire high total sulphur and evaporite mineral e g halite contents usually point to brackish saline conditions during peat accumulation however in case of the karapinar ayranci deposit high sulphur contents can be related to sulphate rich karstic aquifer which contributed to the palaeomire water supply

predicting the quantities of oil and gas generated fromaustralian permian coals bowen basin using pyrolyticmethods abstract the aim of the study was to establish kinetic parameters for gas and oil generation and totest the applicability of the kinetic models to petroleum generation through comparisons withnatural maturity coal sequences 433 c t max ro ro ro modelled ro calculated ro calculated

coal facies in a cenozoic paralic lignite bed krabi basin southern thailand changing peat forming conditions related to relative sea level controlled watertable variations abstract the cenozoic krabi basin in the southern part of peninsular thailand contains about 112 million tons proven coal reserves at present coal is only produced from the bang mark mine located in the southern part of the basin where the main lignite bed is 7 20 m thick the lignite bed occurs in an overall paralic succession the present paper investigates the depositional conditions of an approximately 8 m thick lignite bed main seam in the bang mark mine using organic petrography including maceral ratios and geochemistry the results are further interpreted in a sequence stratigraphic context the lignite is of low rank and is completely dominated by huminite indicating generally oxygen deficient conditions in the precursor mire very low inertinite contents suggest rare occurrences of wildfires the lower part of the lignite bed represents a topogenous fresh water peat mire with open water areas that in few cases may have experienced influx of saline water the peat mire was subjected to periodic inundations and deposition of siliciclastics tissue preservation was relatively poor the upper part of the lignite bed represents a slightly domed fresh water ombrogenous peat mire with a stable watertable and a balance between peat accumulation and accommodation space creation that favoured preservation of plant tissues in general the mire vegetation changed from less woody in the topogenous mire to more arborescent in the ombrogenous mire where plants with suberinised wood cell walls also were more frequent decompacted the lignite bed corresponds to a minimum 11 m thick peat deposit that records from 22 000 to 55 000 years of peat accumulation watertable rise in the peat mire was controlled overall by relative sea level rise in a sequence stratigraphic context the lignite bed overlies a terrestrialisation surface tes sensu diessel 2007 and the lowermost part records peat formation during a falling watertable and a decreasing accommodation peat accumulation ratio terrestrialisation an accommodation reversal surface ars sensu diessel 2007 indicates a change to paludification style of peat formation characterised by rising watertable and a high accommodation peat accumulation ratio another ars marks a gradual change to a situation with a balanced accommodation peat accumulation ratio the overall watertable rise throughout peat formation but at a gradually slower rate from base to top suggests that the lignite bed could be located in the late transgressive systems tract tst

the geology mineralogy petrography and geochemistry of the miocene dursunbey coal within fluvio lacustrine deposits balikesir western turkey abstract the dursunbey coalfield a typical example of coalfields in the western anatolia hosts a mineable coal seam about 9 0 m coal thickness with altered tuff layers within early miocene fluvio lacustrine sequences the aim of this study is to identify peat accumulation conditions and factors controlling the mineralogy and geochemistry of this seam the standard coal features and petrographical mineralogical and elemental compositions display changes throughout the seam ash yields display decreasing trends towards to the upper parts of seam while total c contents and gross calorific values are increasing furthermore the coal facies patterns evidence changes of depositional conditions and vegetation in the palaeomires during initial stages of peat accumulation the contribution of herbaceous peat forming plants were more common and palaeomires were open to detrital inputs whereas woody peat forming were becoming predominant and the water table was stable and high which caused development of anoxic conditions during late stages therefore the content of detrital minerals such as quartz and clay minerals illite smectite and chlorite increases in the lower parts of seam while that of pyrite increases in the upper parts in addition the sem edx data show that matrices of clay mineral aggregates are illitic in composition in the lower parts of seam while those of smectite prevalence are more common below and above altered tuff layers interestingly authigenic rhomboid k feldspar grains are observed within smectite clay aggregates in the samples from the upper parts of seam framboidal pyrite grains and clusters were also commonly identified from these samples as well this data shows that synchronous volcanic inputs were altered within a hydrologically closed system under slight acidic to neutral conditions during late syngenetic stages the enriched elements such as cr ni cs and v display moderate to strong positive correlations with ash yields while al2o3 and k2o indicate an aluminosilicate affinity clay mineral and feldspar considering the presence of metamorphic and ophiolitic rocks in the basement and the adjacent areas clastic inputs into the palaeomire seems to be controlling aluminosilicate affiliated elements additionally the sem edx analyses denoted that ni and as are associated with pyrite the ni and as bearing epigenetic pyrite infillings are mostly identified in coal samples below altered tuff layers hence as and ni enrichments are controlled by precipitation of leached pore waters from altered tuff layers nevertheless as and ni bearing syngenetic pyrite grains and clusters are related with the development of anoxic conditions within palaeomires this could also favour a mo and u enrichment which is another testimony for synchronous volcanic inputs altered under anoxic conditions overall high detrital input ratios from adjacent areas during initial stages of peat accumulation in the study area controlled by enrichments of aluminosilicate affiliated elements whereas during late stages of peat accumulation the development of a hydrologically closed system and redox conditions within the palaeomire caused as ni mo and u enrichments and the formation of smectite and authigenic k feldspars

the petroleum generation potential and effective oil window of humic coals related to coal composition and age abstract a worldwide data set of more than 500 humic coals from the major coal forming geological periods has been used to analyse the evolution in the remaining hydrogen index hi and total quality index qi generation potentials with increasing thermal maturity and the effective oil window oil expulsion window all samples describe hi and qi bands that are broad at low maturities and that gradually narrow with increasing maturity the oil generation potential is completely exhausted at a vitrinite reflectance of 2 0 2 2 ro or tmax of 500 510 c the initial large variation in the generation potential is related to the original depositional conditions particularly the degree of marine influence and the formation of hydrogen enriched vitrinite as suggested by increased sulphur and hydrogen contents during initial thermal maturation the hi increases to a maximum value himax similarly qi increases to a maximum value qimax this increase in hi and qi is related to the formation of an additional generation potential in the coal structure the decline in qi with further maturation is indicating onset of initial oil expulsion which precedes efficient expulsion liquid petroleum generation from humic coals is thus a complex three phase process i onset of petroleum generation ii petroleum build up in the coal and iii initial oil expulsion followed by efficient oil expulsion corresponding to the effective oil window efficient oil expulsion is indicated by a decline in the bitumen index bi when plotted against vitrinite reflectance or tmax this means that in humic coals the vitrinite reflectance or tmax values at which onset of petroleum generation occurs cannot be used to establish the start of the effective oil window the start of the effective oil window occurs within the vitrinite reflectance range 0 85 1 05 ro or tmax range 440 455 c and the oil window extends to 1 5 2 0 ro or 470 510 c for general use an effective oil window is proposed to occur from 0 85 to 1 7 ro or from 440 to 490 c specific ranges for himax and the effective oil window can be defined for cenozoic jurassic permian and carboniferous coals cenozoic coals reach the highest himax values 220 370 mg hc g toc and for the most oil prone cenozoic coals the effective oil window may possibly range from 0 65 to 2 0 ro or 430 to 510 c in contrast the most oil prone jurassic permian and carboniferous coals reach the expulsion threshold at a vitrinite reflectance of 0 85 0 9 ro or tmax of 440 445 c

the effects of clastic sedimentation on organic facies development within a tertiary subbituminous coal bed powder river basin montana u s a abstract the anderson dietz coal is a 25 m thick bed that splits eastward into three benches the anderson dietz 1 and dietz 2 each separated from the other by as much as 45 m of detrital sedimentary rocks petrographic and chemical analyses of the anderson and dietz 1 coal benches suggest that detrital sediments now lithified between the benches were introduced after the peat surface had subsided as a result of either fire or differential compaction of underlying sediments sediments associated with this event had a limited effect upon the quality of the anderson and dietz 1 coal benches ash yields and sulfur contents are elevated only at the very top and bottom of the benches in areas where the benches are not split sulfur content and maceral types indicating degradation increase only in a thin zone 1 m thick that is laterally equivalent to the split sediments however ash yields in this interval increase only slightly 2 5 this indicates that while little sedimentation occurred the peat which formed the coal was inundated by higher ph surface and ground water causing the degradation of plant material

40ar 39ar thermochronology of epidote blueschists from the north d aguilar block queensland australia timing and kinematics of subduction complex unroofing mechanisms proposed for exhumation of blueschists include whole crust uplift and erosion denudation by crustal scale extensional faulting or ductile strain and transport of blocks entrained in rising diapiric masses insight into the unroofing process and the role of granitic plutonism can be gleaned from study of north d9aguilar block in the new england orogen of southeastern queensland australia epidote blueschist facies rocks occur as structurally coherent schists and as blocks in serpentinite matrix melange these subduction underplated rocks formed at depths 18 km and occur in the lower plate of a metamorphic core complex a slate from the upper plate has a whole rock total gas age of 315 ma interpreted as a minimum age for subduction along this part of the paleo pacific margin exhumation of lower plate schists was coeval with overprinting of early high pressure m 1 metamorphic fabrics by a greenschist facies fabric m 2 and was accomplished in part by ductile stretching and normal faulting phengites from most lower plate schists yield 40 ar 39 ar plateau ages of ca 299 296 ma recording the time elapsed since the schists cooled below 350 50 c following m 2 plateau shaped age spectra and small structural depth related age gradients indicate rapid cooling of schists in the footwall of a present day low angle normal fault samples from deeper levels of the lower plate remained at 350 c for 35 m y longer than the other samples and contain extraneous ar possibly absorbed from fluids originating at depth at ca 307 ma a granodiorite pluton was intruded into the lower plate near the peak of m 2 a synkinematically intruded in part mylonitic pluton increased the regional m 2 fabric to amphibolite facies in its aureole heat from the granitic pluton and perhaps others like it at depth may have played a strain softening role in formation of the core complex similar 40 ar 39 ar cooling ages for different blueschist and greenschist blocks in serpentinite matrix melange support the view that the australian melange was uplifted by extensional tectonic processes unrelated to serpentinite diapirism

paleomagnetic data from the new england orogen eastern australia and implications for oroclinal bending orogenic curvatures oroclines are common in modern and ancient orogens but the geodynamic driving forces of many oroclines remain controversial here we focus on the new england oroclines of eastern australia the formation of which had been previously broadly constrained to the early middle permian this time interval encompasses periods of both back arc extension at 300 280 ma and subsequent contractional deformation hunter bowen orogeny that commenced at 270 ma along the paleo pacific and gondwanan subduction plate boundary we present new paleomagnetic data from volcanic rocks that were extruded during the transition from extension to contraction at 272 ma and we show that the oroclinal structure must have formed prior to the emplacement of the volcanic rocks our results thus indicate that oroclinal bending in the southernmost new england orogen has been completed prior to the onset of middle permian contractional deformation it is therefore concluded that the oroclines have likely formed during back arc extension and that a major contribution to the orogenic curvature was driven by trench retreat

mechanical and hydraulic properties of nankai accretionary prism sediments effect of stress path 1 we have conducted triaxial deformation experiments along different loading paths on prism sediments from the nankai trough different load paths of isotropic loading uniaxial strain loading triaxial compression at constant confining pressure pc undrained pc reduction drained pc reduction and triaxial unloading at constant pc were used to understand the evolution of mechanical and hydraulic properties under complicated stress states and loading histories in accretionary subduction zones five deformation experiments were conducted on three sediment core samples for the nankai prism specifically from older accreted sediments at the forearc basin underthrust slope sediments beneath the megasplay fault and overthrust upper shikoku basin sediments along the frontal thrust yield envelopes for each sample were constructed based on the stress paths of pc reduction using the modified cam clay model and in situ stress states of the prism were constrained using the results from the other load paths and accounting for horizontal stress results suggest that the sediments in the vicinity of the megasplay fault and frontal thrust are highly overconsolidated and thus likely to deform brittle rather than ductile the porosity of sediments decreases as the yield envelope expands while the reduction in permeability mainly depends on the effective mean stress before yield and the differential stress after yield an improved understanding of sediment yield strength and hydromechanical properties along different load paths is necessary to treat accurately the coupling of deformation and fluid flow in accretionary subduction zones

orogenesis without collision stabilizing the terra australis accretionary orogen eastern australia the neoproterozoic to end paleozoic terra australis orogen extended along the gondwana margin of the paleo pacific ocean and it now provides a detailed record of orogenic activity and continental stabilization within an ongoing convergent accretionary plate margin new geochronological data from end paleozoic plutonic and volcanic rocks associated with the gondwanide orogeny in the new england region of eastern australia integrated with information on the nature and timing of associated sedimentation deformation and metamorphism allow resolution of a high fidelity record of orogenesis at the end of the carboniferous around 305 ma convergent margin magmatism which had been active along the western margin of the new england region terminated and was followed by a short pulse of regional compressional deformation and metamorphism marking the commencement of the tablelands phase of gondwanide orogenesis deformation was almost immediately followed by the onset of clastic sedimentation and local calc alkaline volcanism dated at 293 ma in the extensional barnard basin emplacement of the two new england s type granitic suites the bundarra and the hillgrove suites along with localized high temperature low pressure metamorphism was essentially contemporaneous ranging in age from 296 to 288 ma and overlapped in time with i type magmatism and the switch from regional compression to extension and barnard basin rifting the hunter bowen phase of the gondwanide orogeny commenced with contractional deformation resulting in termination of sedimentation in the barnard basin and regional deformation and metamorphism across new england and into the sydney and gunnedah basins to the west at around 265 260 ma contractional loading of the sydney and gunnedah basins resulted in their conversion from extensional to foreland basins which received ongoing pulses of sediment from the new england orogenic welt until 230 ma the hunter bowen phase was associated with widespread i type plutonism and volcanic activity in new england that ceased around 230 ma marking the termination of gondwanide orogenesis orogenesis occurred in an evolving convergent plate margin setting s and i type magmatic activity ranging in age from ca 300 to 230 ma represents a stepping out of arc magmatism from the western margin of new england prior to 305 ma into the preexisting arc trench gap there is no evidence that deformation was related to the collision of the convergent margin with a major lithospheric mass and the widespread development of extensional basins in the eastern third of australia in the early permian indicates control by phenomena acting on a continental scale probably changing plate kinematics associated with the amalgamation of pangea

organic facies development within middle jurassic coal seams danish central graben and evidence for relative sea level control on peat accumulation in a coastal plain environment abstract during middle jurassic times peat accumulated in coastal plain environments in an overall transgressive setting in the sogne basin danish central graben in the north sea the coal seams occur in nonmarine to marginal marine deposits coal petrographic analyses of the seams in the west lulu 2 well supplemented with a sequence stratigraphic analysis suggest that peat accumulation was controlled by relative sea level changes in west lulu 2 the coal bearing upper part of the middle jurassic is divided into sequences a and b the sediments of sequence a are part of a transgressive systems tract whereas the overlying sequence b contains lowstand and transgressive systems tract deposits the coals are situated in the transgressive systems tracts the coal seams formed during a rapid relative sea level rise are generally characterized by petrographic features related to a permanently high groundwater table coals formed during a slow rise typically are drier in their petrographic composition the highest pyrite contents are observed in the wet coals the coal seams represent terrestrial equivalents to marine flooding surfaces or to transgressive surfaces if they are situated at the base of a transgressive systems tract a thick coal seam zone is associated with the stratigraphic level of the maximum flooding surface which correlates with the time of formation of the highest accommodation space

composition and organic maturity of middle jurassic coals north east greenland evidence for liptinite induced suppression of huminite reflectance abstract middle jurassic coals from kuhn o north east greenland may contain up to 85 vol liptinite principally resinite up to 68 6 vol the coals are thus petrographically comparable to the middle jurassic muslingebjerg formation coals at hochstetter forland approximately 40 50 km to the north and they are inherently excellent petroleum source rocks liptinite poor 6 0 vol coal samples from both kuhn o and hochstetter forland yield mean random huminite reflectance values of 0 49 0 53 ro implying a rank of sub bituminous a above a threshold value somewhere between 3 and 24 vol resinite and 6 and 35 vol total liptinite significant reflectance suppression is induced and between 24 and 69 vol resinite and 35 and 85 vol total liptinite a nearly linear inverse relationship exists between the content of liptinite resinite and the mean random reflectance values at the highest liptinite resinite contents reflectance suppression may be up to 0 23 ro the reflectance suppression is related to bitumen adsorption caused by bitumen expulsion from resinite and total reflectance distributions of the huminite fractions suggest that the reflectance of all huminite macerals is lowered with increasing liptinite resinite content

contrasting modes of eclogite and blueschist exhumation in a retreating subduction system the tasmanides australia abstract blueschists and eclogites located in the tasmanides of eastern australia preserve evidence of contrasting modes of exhumation a review of structural metamorphic geochronological and geochemical data indicates that these hp metamorphic rocks can be sub divided into three main groups i eclogite blueschists with calc alkaline and tholeiitic affinities contained within thick sedimentary sequences called continental hp rocks ii moderate pressure thermobarometric and geochronological data from eclogites and blueschists in the peel manning fault system new england orogen also provide evidence for discontinuous exhumation of subducted oceanic rocks these data indicate that eclogites were exhumed from depths of 70 km to 30 km during the ordovician 490 470 ma with terminal exhumation and exposure along the peel manning fault system probably occurring during the permian based on these timing constraints we suggest a model where hp rocks reside between depth dependant exhumation circuits for considerable lengths of time

anatomy of recent and peatified calluna vulgaris stems implications for coal maceral formation abstract anatomical characteristics of peatified calluna vulgaris stems isolated from a selection of northwest european raised bog peat deposits were compared with intact stems in order to reveal anatomical modifications caused by the peatification process four main decomposition processed were discerned 1 loss of structural integrity of cell walls and cell inclusions 2 gelification and swelling of cell walls 3 discolouration of cell walls and 4 deposition of matter in cell lumina fibre tracheids and wood parenchyma appear to be the most affected cell types the two main decomposition trends discerned in these were related to different fungal types precipitation of decay products was mainly observed in vessels bark tissues primary xylem and medullary parenchyma were characterized by an excellent anatomical preservation in the first stages of peatification a rapid decrease in cell contents was observed in bark tissues swelling and gelification was mainly seen in cell walls of the cambium and vessels we conclude that different types of cell walls respond differently to decay conditions this is probably related to differences in the original cell wall chemistry a high intra and intracellular variability in degree of preservation was sometimes observed in identical tissues the microscopic variability arising during peatification of wood and bark testifies to the heterogeneity of coal macerals derived from these tissues