alkylbiphenyls in ancient sediments and petroleums abstract c 1 and c 2 alkylbiphenyls have been analysed in crude oils and sediment extracts by capillary gas chromatography after preliminary isolation procedures involving tlc and hplc the abundance of 2 methylbiphenyl relative to 3 methylbiphenyl has been measured in samples from two sedimentary sequences 2 methylbiphenyl decreases in relative abundance with increasing thermal maturity of the sediments in both sedimentary sequences these isomeric methylbiphenyls are potentially useful as thermal maturity indicators for crude oils

applications of fluorescence microscopy to study of pores in tight rocks observation of pore structures in thin section by traditional impregnation with blue dyed epoxy becomes difficult when the pores are smaller than about 1 micrometer and or linear in shape these types of pores are common in many low permeability gas reservoirs such as coal shale and tight sandstone incident light fluorescence microscopy can be used to observe small narrow pore structures in tight rocks this common medical technique can be adapted to petrography by staining the impregnation epoxy with fluorescent rhodamine b dye along with the usual blue dye and using an incident light microscope equipped for epifluorescence to observe the prepared thin section under excitation of green light at a wavelength of 5 400 angstroms rhodamine fluoresces a brilliant reddish orange clearly showing impregnated pore spaces a dichromatic interference filter in the light path passes the reddish orange light and blocks nonfluorescing mineral grains so that only the pore structure is visible fluorescing epoxy behaves as an emission source and even submicron size pores which may be narrower than the wavelengths of visible light become visible if they are impregnated the incident light configuration of the microscope also allows the observation of impregnated pore spaces in opaque materials such as coal fluorescence microscopy not only has potential for studying pore structures in tight sedimentary rocks but also can be applied to crystalline rock and other materials with narrow linear or small pores

anisotropy of magnetic susceptibility and p wave velocity in core samples from the taiwan chelungpu fault drilling project tcdp the anisotropy of magnetic susceptibility ams and anisotropy of p wave velocity apv were characterized in core samples retrieved from the tcdp hole a at depths ranging from 600m to 1400m thus cutting across the thrust fault that ruptured during the 1999 chi chi earthquake our data show that the ams was similar for all the samples regardless of the lithologic contrasts with a magnetic fabric characteristic of weakly deformed sedimentary rocks that had undergone layer parallel shortening this robust observation applies to both the siltstones and sandstones at all depths investigated in contrast the apv data reflect fundamental differences between the elastic fabrics in the two facies while apv of the siltstone samples is controlled by a preferred orientation of the matrix minerals the apv of the sandstones is greatly influenced by microcrack porosity with a preferred orientation parallel to the maximum principal direction of paleostress and tectonic deformation these ams and apv data obtained in tcdp hole a at locations not directly impacted by the coseismic rupture provide a first order petrofabric framework for the characterization of hydromechanical anisotropy in the chelungpu fault system

alkyldibenzofurans in terrestrial rocks influence of organic facies and maturation abstract dibenzofuran dbf dibenzothiophene dbt and phenanthrene phe have been determined along with their methyl derivatives mdbfs mdbts mps in coals carbonaceous shales and mudstones of lower cretaceous to upper carboniferous ages from the elmworth gas field canada and from the sakoa madagascar and ruhr coal germany basins the samples contained mainly terrestrial organic matter with thermal maturities in the 0 7 1 9 mean vitrinite reflectance rr range the pronounced predominance of mdbfs over mdbts in the sakoa samples is typical of plant debris deposited in lacustrine swamp environments onset of intense mdbf generation occurs at fairly low rank 0 77 rr as indicated by elevated concentrations of 50 120 g mdbfs g total organic carbon toc influences of lithology organic matter type and maturity on distributions of the target compounds were extracted from the molecular concentration data by multivariate statistical methods such as principal components analysis pca and fuzzy c means cluster analysis with nonlinear mapping nlm a specific source effect on 1 mdbt concentrations suggests that lichens contributed to the senescent coal forming forest in the sakoa coal basin alkyldibenzofurans hence are potential lichen biomarkers mdbfs can be used as maturity indicators only beyond 1 0 rr where ruhr coals displayed a distinct increase in the 1 4 mdbf ratio

variation of pore fabric across a fold thrust structure variations of pore orientation pore shape porosity and hydraulic permeability within a siltstone unit of a fold thrust structure are determined using magnatic pore fabric analysis mercury injection porosimetry and scanning electron microscopy sem while samples in the foreland show evidence for the preservation of depositional pore geometry the progressively deformed thrust sheet reveals increasingly oblate pore fabric anisotropy with microcrack planes oriented normal to the tectonic transport direction porosity pore throat sizes and permeability show corresponding spatial variations across the structure independent of the deformation state within the thrust sheet pore and magnetic grain fabric correlate closely in orientation

magnetic susceptibility anisotropy of rocks saturated with ferrofluid a new method to study pore fabric abstract the shape effect of ferrofluid filled cavities on the anisotropy of magnetic susceptibility ams is examined for different geometries principal directions of magnetic susceptibility correspond to principal axes of the shape of the cavity elongation directions and axial ratios are reflected in the ams response which for simple geometries is explained by the anisotropy of the demagnetizing factor the experiments can be carried further for the analysis of pore structure in natural rock samples techniques developed for the injection of fractionated ferrofluid into a porous sandstone successfully lead to a homogeneous saturation of the sample the method potentially provides a new means to determine three dimensional pore fabric anisotropy and to relate it to the anisotropy of various petrophysical parameters

early cretaceous synrift uplift and tectonic inversion in the loppa high area southwestern barents sea norwegian shelf tectonic inversion of rift basins is most commonly reported in the literature to occur after rifting has ceased in contrast we present evidence for synrift localized tectonic inversion from the loppa high area southwestern barents sea and present a model for the formation of inversion structures as a result of differential uplift the structures are of early barremian to mid albian age c 131 105 ma and are focused in or near pre existing extensional boundary faults along the margins of the loppa high inversion is interpreted to be the result of uplift of the high along its inclined boundary faults leading to space accommodation problems as uplift was not properly compensated by extension in the region the model constrains the initiation of uplift of the loppa high to the early barremian and shows that the asymmetric margin configuration of the high may have led to a bulk clockwise rotation of the high around a vertical axis during uplift the cause of uplift is not fully understood but is suggested to be linked to contemporaneous extreme lithospheric thinning in neighbouring basins to the west processes involved may include isostatic flexure thermal heating lithological phase changes and or far field stresses although these aspects need to be further tested

jurassic to early cretaceous basin configuration s in the fingerdjupet subbasin sw barents sea abstract the fingerdjupet subbasin in the southwestern barents sea sits in a key tectonic location between deep rifts in the west and more stable platform areas in the east its evolution is characterized by extensional reactivation of n s and nne ssw faults with an older history of late permian and likely carboniferous activity superimposed on caledonian fabrics reactivations in the listric nne ssw terningen fault complex accommodated a semi regional rollover structure where the fingerdjupet subbasin developed in the hangingwall in parallel the randi fault set developed from outer arc extension and collapse of the rollover anticline n s to nne ssw faults and the presence of other fault trends indicate changes in the stress regime relating to tectonic activity in the north atlantic and arctic regions a latest triassic to middle jurassic extensional faulting event with e w striking faults is linked to activity in the hammerfest basin cessation of extensional tectonics before the late jurassic in the fingerdjupet subbasin however suggests rifting became localized to the hammerfest basin the late jurassic was a period of tectonic quiescence in the fingerdjupet subbasin before latest jurassic to hauterivian extensional faulting which reactivated n s and nne ssw faults barremian se prograding clinoforms filled the relief generated during this event before reaching the bjarmeland platform high angle nw prograding clinoforms on the western bjarmeland platform are linked to early barremian uplift of the loppa high the terningen fault complex and randi fault set were again reactivated in the aptian along with other major fault complexes in the sw barents sea leading to subaerial exposure of local highs this activity ceased by early albian post upper albian strata were removed by late cenozoic uplift and erosion but later tectonic activity has both reactivated e w and n s nne ssw faults and also established a nw se trend

fabric analysis using the intercept method abstract the intercept method is a convenient yet powerful method for the numerical analysis of fabrics for geological applications it can be used when a set of objects e g pores grains or aggregates of a specific mineral lineaments etc with unique characteristics can be identified in an image the intercept method analyses boundaries of objects as a population of lines how intercepts are definined is therefore important in order to establish the significance of the intercept counts when the method is applied to digital images the subdivision of the information into square pixels must also be considered we apply a linear filter which minimizes the effects of grid anisotropy on the counting of intercepts analysis of the resulting rose of intercept counts by a fourier series considerably facilitates the interpretation of the data a rose of directions can readily be derived for the phase boundaries if a population of objects can be assumed to have started with an originally isotropic orientation and to have been deformed passively the fourier components of the rose of intercepts also give the sectional strain the fourier components also permit an objective test of the validity of describing a fabric as resulting from a homogeneous strain on an initially isotropic section two computer programs for the counting and analysis of intercepts on digital images are presented and applied in four examples which illustrate the usefulness of the intercept method for magmatic fabric measurement strain analysis and lineament analysis we also illustrate the importance of fourier series decomposition of rose of intercept counts for fabric interpretations intercept results are also shown to be compatible with those derived by other methods eigenvector surfor inertia tensor autocorrelation methods

detection of natural weathering of upper mcalester coal and woodford shale oklahoma u s a abstract natural weathering refers to the natural oxidation of organic and inorganic matter in rocks at the surface and in the shallow subsurface the objective of this study is to apply routine geochemical analyses including organic petrography to coal and shale samples extending from the weathered to unaltered zones to illustrate the effects of weathering on organic matter in coal and shale some significant observations from the upper mcalester coal and the woodford shale are 1 a sulfate index si using sulfur form analysis data that reveals the transformation of pyrite to sulfate minerals is a very sensitive weathering indicator it increased in weathered samples 2 rock eval pyrolysis data such as hydrogen index hi and oxygen index oi are very sensitive to weathering oi hi increased in weathered samples 3 vitrinite reflectance decreased in weathered samples and 4 petrographic signs of weathering include microfractures pitted surface dark reaction rims and high relief sulfate index and petrographic signs of weathering should be used on surface and shallow subsurface rock samples as an indication of the extent of weathering the validity of other analyses can then be evaluated accordingly

effect of coal weathering on some geochemical parameters abstract the effect of coal weathering on some geochemical parameters was studied seven pairs of fresh and altered samples were selected from different venezuelan coal deposits the following analyses were performed water and ash percent heating value bitumen content and composition infrared spectroscopy n alkane distribution and humic substances concentration hs as weathering proceeds there is a corresponding change in hs concentration most geochemical parameters show small changes with hs concentrations below 15 for intense weathering all parameters measured show important modifications such changes are due to the breaking of the coal s macrostructure

biological origin of tetracyclic diterpanes n alkanes and other biomarkers found in lower carboniferous gondwana coals niger abstract the saturated hydrocarbons of coal samples of the anou araren mine tim mersoi basin niger republic have been studied by gc and gc ms chromatograms revealed rather unusual n alkane distributions dominated by compounds in the c 20 c 23 range and showing a rapid and irregular decrease towards higher molecular weights these signatures appear to be typical of the paleozoic gondwana swamps flora unlike typical low maturity terrestrial organic matter characterized by a dominance of odd carbon number n alkanes in the c 27 c 33 range which could be attributed to angiosperms the presence of large amounts of polycyclic diterpanes ent beyerane phyllocladanes and kauranes is unexpected in samples of that age since these compounds are usually thought to be derived from conifers which supposedly had not yet evolved at the time a more likely explanation is that these diterpanes could be derived from biological precursors of the conifers

permeability anisotropy and its relations with porous medium structure 1 the complete permeability tensor of 18 porous rock cores was determined by means of x ray tomography monitoring during the displacement of a salty tracer to study the effect of the pore space geometry on the anisotropy of permeability we compared the three dimensional shape of the invasion front with the x ray porosity maps obtained before injection the samples clean and shale bearing sandstones limestones and volcanic rocks belong to a broad variety of granulometry and pore space geometry their porosity ranges from 12 to 57 and their permeability ranges from 1 5 10 14 to 4 10 12 m2 for sandstones the permeability anisotropy is well correlated with the presence of bedding for volcanic rocks it is clearly related to the orientation of vesicles or cracks however for limestones no evident link between the geometry of the porous network and the permeability anisotropy appears probably because of the influence of the nonconnected porosity that does not contribute to the hydraulic transport this systematic work evidences the ability and the limitations of the tracer method to characterize the anisotropy of permeability in the laboratory in a simple and rapid way

effects of biodegradation on australian permian coals abstract permian coals from blackwater poitrel and moura bowen basin queensland have been extracted and characterised by detailed organic geochemical techniques a variety of source related aliphatic and aromatic biomarker parameters indicate that these coals from three different locations are similar in terms of organic matter type and palaeoenvironment of deposition the hydrocarbons extracted from these coals appear to have been generated from predominantly plant derived organic matter deposited in a fluvio deltaic environment moderately high pr ph ratios the high proportion of c 29 steranes and very low sterane to hopane ratios are indicative of their largely terrestrial source molecular maturity parameters derived from aliphatic and aromatic biomarkers corroborate a measured maturity of 1 0 1 1 r o for these medium volatile bituminous coals the aliphatic and aromatic hydrocarbon distributions in these coals also allow their differentiation into two groups biodegraded moura coals and non degraded blackwater and poitrel coals comparison of various compound ratios from the degraded and non degraded coals indicate the dependence of susceptibility to biodegradation on precise molecular structures major aromatic compound classes in coals generally regarded as being more resistant may be microbially altered before branched cyclic alkanes are affected and even before the n alkanes are completely removed as reported in crude oils susceptibility to biodegradation of aromatic hydrocarbons decreases with increasing number of aromatic rings and with increasing number of alkyl substituents furthermore alkylnaphthalenes with 1 6 dimethyl substitution patterns are more susceptible to degradation than other alkylnaphthalene isomers this study reveals that biodegradation may alter the hydrocarbon composition of coals in a similar way to that observed in crude oils or oil spills except that aromatic hydrocarbons are altered relatively earlier than aliphatic hydrocarbons in coals compared to oils

episodic cenozoic tectonism and the development of the nw european passive continental margin the north atlantic margins are archetypally passive yet they have experienced post rift vertical movements of up to kilometre scale the cenozoic history of such movements along the nw european margin from ireland to mid norway is examined by integrating published analyses of uplift and subsidence with higher resolution tectono stratigraphic indicators of relative movements including results from the stratagem project three episodes of epeirogenic movement are identified in the early mid and late cenozoic distinct from at least one phase of compressive tectonism two forms of epeirogenic movement are recognised referred to as tilting coeval subsidence and uplift rotations 1 over distances of 100s of kilometres and sagging strongly differential subsidence rotations up to 4 over distances 100 km each epeirogenic episode involved relatively rapid 10 ma km scale tectonic movements that drove major changes in patterns of sedimentation to find expression in regional unconformity bounded stratigraphic units early cenozoic tilting late paleocene to early eocene c 60 50 ma caused the basinward progradation of shelf slope wedges from elongate uplifts along the inner continental margin and from offshore highs mid cenozoic sagging late eocene to early oligocene c 35 25 ma ended wedge progradation and caused the onset of contourite deposition in deep water basins late cenozoic tilting early pliocene to present 4 0 5 ma again caused the basinward progradation of shelf slope wedges from uplifts along the inner margin including broad dome like features and from offshore highs the early mid and late cenozoic epeirogenic episodes coincided with atlantic plate reorganisations but the observed km scale tectonic movements are too large to be accounted for as flexural deflections due to intra plate stress variations mantle lithosphere interactions are implied but the succession of epeirogenic episodes of differing form are difficult to reconcile with the various syn to post rift mechanisms of permanent and or transient movements proposed in the hypothetical context of a plume beneath iceland the epeirogenic movements can be explained as dynamic topographic responses to changing forms of small scale convective flow in the upper mantle tilting as coeval upwelling and downwelling above an edge driven convection cell sagging as a loss of dynamic support above a former upwelling the inferred cenozoic succession of epeirogenic tilting sagging and tilting is proposed to record the episodic evolution of upper mantle convection during ocean opening a process that may also be the underlying cause of plate reorganisations the postulated episodes of flow reorganisation in the ne atlantic region have testable implications for epeirogenic movements along the adjacent oceanic spreading ridge and conjugate continental margin as well as on other atlantic type passive margins

new insights into the tectono stratigraphic evolution of the southern stappen high and its transition to bjornoya basin sw barents sea abstract within the context of the southwestern barents sea the southern stappen high and its transition to the bjornoya basin are still underexplored improved quality seismic reflection data are utilised to describe new insights into the paleozoic to early cenozoic tectono stratigraphic evolution of the area as well as to discuss the structural inheritance and the rift development well defined syn rift wedges and better resolution images for both the deep carboniferous and permian successions are revealed in particular both the mid carboniferous and late permian earliest triassic extensional phases are characterized by widespread ne sw oriented normal faults that are mostly westward dipping although triassic is mostly considered as a tectonically stable period in the barents sea in the southern stappen high there is clear identification of a localised depocentre named herein intra stappen basin where syn tectonic geometries characterize the upper paleozoic and triassic deposits regional correlation to middle and upper triassic outcrops in southwestern svalbard reveals possible progradation from a west northwest northeast greenland provenance as a western sediment source area during the triassic in addition to the well known eastern sediment source area thin but distinct jurassic sequences are expected to be present on stappen high associated with prominent regional nw se extension throughout late jurassic that culminated during the earliest cretaceous furthermore structural and stratigraphic relations are observed within the study area that clearly indicate a distinct early aptian rift phase with increasing evidence for its occurrence in the southwestern barents sea upper cretaceous sequences bounded by major low angle west dipping detachment faults are observed in southwest stappen high during early cenozoic the study area was located at the proximity of the paleo coastline and paleo shelf edge for both paleocene and eocene gravity mass waste deposits these are most probably related to a progressively evolving steep bathymetric gradient between the developing margin mainly towards the west and to the south and the uplifted stappen high

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

a program for magnetic susceptibility equivalent pore conversion pore magnetic anisotropy can be used to estimate the average geometry of void spaces in rocks in the form of the equivalent pore ep ellipsoid direct computation of ep from measured magnetic susceptibility is impossible we present a method and a matlab program for automatic magnetic susceptibility equivalent pore conversion input data are the magnetic parameters p and t or l and f representing the bulk magnetic anisotropy and the intrinsic susceptibility of the fluid used in the measurement ep is estimated iteratively by a repeated look up table procedure using p and t values computed in a coarse grid of ep axial ratios the program may be downloaded from the earthref org digital archive

petrophysical and magnetic pore network anisotropy of some cretaceous sandstone from tushka basin egypt summary pore magnetic fabric is a well established technique for the determination of pore elongation and preferred directions for migration of the interstitial fluids this study further exemplify this technique on a set of the nubia sandstones through a comparison with the pore anisotropy obtained from measuring permeability in three orthogonal directions in a gaz permeameter the nubia sandstones are represented in tushka area south egypt by quartz arenite of large porosity 29 40 per cent which was measured on thin sections parallel and perpendicular to the bedding plane and petrophysically by helium pycnometry and ferrofluid injection at 1 bar pressure petrographically there is a detectable difference between the porosity values in the bedding plane and in the perpendicular direction indicating inhomogeneity in the pore space network distribution the petrophysical studies indicate large porosity and permeability values with some differences between the helium and ferrofluid porosity due to presence of micro pore spaces not accessible for the ferrofluid molecules having relatively high diameters and injected at low pressure an overall agreement is observed between the permeability anisotropy and the magnetic grain and pore fabrics magnetic anisotropy measured before and after ferrofluid injection the three fabrics are mainly dominated by a bedding parallel foliation in a few cases maximum permeability appears to be perpendicular to bedding within the bedding plane maximum pore elongation direction from ferrofluid injection is nnw for adindan and kesieba formations and nw for abu simbil formation the maximum pore elongation direction for abu ballas samples showed a direction fluctuating around the e w direction the main fault trends in tushka area the pore fabric of abu ballas formation seems therefore to be structurally controlled while it would be originated from palaeocurrent directions in the other formations

book reviews palaeomagnetism and diagenesis in sediments ed by d h tarling and p turner the geological society london special publications no 151 214 pp f67 00 111 00 isbn 1 86239 028 2

cenozoic uplift and subsidence in the north atlantic region geological evidence revisited abstract the topographic evolution of the passive margins of the north atlantic during the last 65 myr is the subject of extensive debate due to inherent limitations of the geological geomorphological and geophysical methods used for studies of uplift and subsidence we have compiled a database of sign time and amplitude where possible of topographic changes in the north atlantic region during the cenozoic 65 0 ma our compilation is based on published results from reflection seismic studies aft apatite fission track studies vr vitrinite reflectance trends maximum burial sediment supply studies mass balance calculations and extrapolation of seismic profiles to onshore geomorphological features the integration of about 200 published results reveal a clear pattern of topographic changes in the north atlantic region during the cenozoic 1 the first major phase of cenozoic regional uplift occurred in the late palaeocene early eocene ca 60 50 ma probably related to the break up of the north atlantic between europe and greenland as indicated by the northward propagation of uplift it was preceded by middle palaeocene uplift and over deepening of some basins of the north sea and the surrounding areas 2 a regional increase in subsidence in the offshore marginal areas of norway the northern north sea the northern british isles and west greenland took place in the eocene ca 57 35 ma 3 the oligocene and miocene 35 5 ma were characterized by regional tectonic quiescence with only localised uplift probably related to changes in plate dynamics 4 the second major phase of regional uplift that affected all marginal areas of the north atlantic occurred in the plio pleistocene 5 0 ma its amplitude was enhanced by erosion driven glacio isostatic compensation despite inconclusive evidence this phase is likely to be ongoing at present

saturated hydrocarbon biomarkers in oils of late precambrian age from eastern siberia abstract large quantities of petroleum derived from source rocks of late precambrian early cambrian age have been discovered in the lena tunguska region of eastern siberia over the last twenty five years we have examined three oils with presumed late precambrian vendian source rocks from this region for c 15 saturated hydrocarbon biomarkers using gas chromatography gc and gas chromatography mass spectrometry gc ms our results show these oils to have many characteristics in common with other oils of similar age from eastern siberia and oman amongst the compounds detected in the three oils analyzed were 1 n alkanes which show a marine derived distribution 2 centrally branched monomethyl alkanes 3 acyclic isoprenoids pr ph 1 4 tricyclic and tetracyclic terpanes 5 hopanes 6 c 29 unrearranged steranes and 7 c 30 nuclear steranes all of these compounds with the exception of the 4 methylsteranes which on current biochemical knowledge are unexpected in oils of this age can be assigned a prokaryotic source this and other evidence such as the lack of diasteranes suggest microorganism were the major contributors to organic matter deposited as part of a carbonate source rock

late cretaceous and cenozoic intra plate compressional deformations in the alpine foreland a geodynamic model abstract the mesozoic grabens and wrench induced troughs of western and central europe developed in response to triassic early cretaceous intra plate tensional stresses which affected the arctic north atlantic and the tethys borderlands during the rifting phase preceding the opening of the respective oceans this resulted in the fragmentation of the continental crust of the alpine foreland during the late cretaceous and tertiary alpine orogeny collision related compressive stresses exerted on the foreland induced the reactivation of these fracture systems causing the inversion of mesozoic grabens and the uplifting of major basement blocks at distances up to 1300 km to the north of the present alpine deformation front the structural style of these inverted basins and basement uplifts is indicative of compressional and transpressional deformations the total amount of crustal shortening associated with these deformations is unlikely to exceed a few tens of kilometres these displacements require a coupling between the foreland and the orogen at the alpine a subduction zones and within the foreland a decoupling at intra crustal levels between the crust and mantle and or at deeper lithospheric levels the example of the alpine foreland indicates that compressive stresses inducing major deformations can be transmitted from a collisional plate boundary through continental lithosphere over distances of up to 1300 km circumstantial evidence suggests that collision related compressive stresses not large enough to give rise to significant deformations can be transmitted through continental lithosphere over even greater distances

biomarkers and aromatic hydrocarbons in bituminous coals of upper silesian coal basin example from 405 coal seam of the zaleskie beds poland abstract this paper presents the geochemical characteristics of hard coals from the 405 coal seam found in several mines in the upper silesian coal basin poland the coals classifying as of medial coalification types d and c and as para and orthobituminous coals show variable technical chemical and petrographic properties vitrinite reflectance values range from 0 65 to 1 24 cdaf from 79 2 to 88 3 wt and vdaf from 23 7 to 37 4 wt maceral composition in all of the coals studied is dominated by vitrinite macerals 43 5 74 0 gas chromatography mass spectrometry was applied to assess organic matter sources and ranks using several biomarker and aromatic hydrocarbon parameters distributions of n alkanes acyclic isoprenoids diterpenoids steranes and triaromatic steroids indicate that the organic matter in the coals analysed is derived mostly from terrestrial vascular plants the biogenic organic matter was deposited mostly in an estuarine deltaic environment with a normal to low water level in a few cases a marine lagoonal or paludal environment is possible tetracyclic diterpanes such as phyllocladanes and kauranes indicators of the podocarpaceae and araucariceae families are explained by proposing input of organic matter deriving from voltziales plants which may have been able to synthesise these compounds biomarker and aromatic hydrocarbon parameters of thermal maturity in the coals show a clear correlation to vitrinite reflectance values and carbon content indicating degrees of thermal maturity in the range from early to advanced catagenesis frictional heat related to the klodnica fault movement caused aberrations in values of aromatic hydrocarbon maturity parameters in coals sampled

the impact of water washing biodegradation and self heating processes on coal waste dumps in the rybnik industrial region poland abstract water washing biodegradation and self heating impacts on coal waste features were investigated on four sample sets fresh coal wastes sampled less than one week after dumping samples from gullies in coal waste dumps self heated material and bierawka river sediment mixed with coal coal waste particles rock eval pyrolysis petrography and gas chromatography mass spectrometry gc ms were applied to assess degree of organic matter alteration it was found that water washing and self heating did not influence the vitrinite reflectance rock eval pyrolysis results better reflected the secondary changes in organic matter namely s 2 toc and hi t max allowed their extent to be defined changes were noted in other geochemical e g n alkane parameters 2 1 increased and n c 23 n c 31 decreased whereas pr ph pr n c 17 and ph n c 18 ratios increased slightly compared to fresh coal waste the hunt diagram allows discrimination between water washed and biodegraded samples from unaltered fresh coal waste similarly changes in distributions of phenols alkyl aromatic hydrocarbons and polycyclic aromatic hydrocarbons pahs reflect degree of water washing self heating strongly affects distributions of some biomarkers such as n alkanes pr and ph whereas pentacyclic triterpane distributions were generally well preserved phenols occur in greatest amount in self heated wastes probably released from heated vitrinite domination of 2 3 ring pah rings indicated the bitumen precipitation zone and well differentiated burnt out wastes recent organic matter input is seen in increased cpi carbon preference index values

regional constraints of the sorkapp basin a carboniferous relic or a cretaceous depression abstract the sorkapp basin nw barents shelf contains a comprehensive sedimentary succession that provides insight into regional tectonics and depositional development of the shelf from the devonian to the cretaceous with its location east of the mid atlantic spreading ridge and south of svalbard the basin serves as an important link between the offshore and onshore realms this study subdivides this sparsely studied basin into six main seismic units three paleozoic and three mesozoic a metamorphic basement together with assumed devonian sedimentary deposits form the foundation for a chiefly carboniferous basin the basin forms a syncline with infill showing limited fault influence overlying the early infill are late carboniferous deposits which show less lateral variation in thickness but also active growth on the few faults showing significant displacement the overlying platform deposits of the latest carboniferous and permian show a change in depositional geometry with onlapping deposits towards the east probably resulting from uplift of the stappen high and regional flooding subsequent particularly late triassic sedimentation shows a more distinctly progradational pattern with a dominantly southeastern source for sediments during this shallow shelf filling stage the sorkapp basin is sheltered by the gardarbanken high blocking the early triassic clinoform development the high was transgressed in the middle triassic and the platform edge progressively approached the present svalbard coastline the youngest mesozoic unit forms a separate saucer shaped depocenter west of the sorkapp basin where deposits are truncated by the seafloor in a mid basin position and across the gardarbanken high the depositional pattern for this succession correlates with the outcrop pattern of the adventdalen group implying a post middle jurassic to cretaceous age the sorkapp basin has been referred to as a cretaceous feature based in this depocenter however the foundations are much older and the cretaceous depression is located west of the deeper basin accordingly we propose the informal term sorkapp depression for the cretaceous basin

the eurekan deformation in the arctic an outline the evolution of the eurekan deformation zones in the arctic is closely related to the development of the circum greenland plate boundaries in early cenozoic times 53 34 ma mostly the eurekan orogeny or deformation has been interpreted as a predominantly compressive tectonic event but the eurekan deformational history in the arctic was not the result of a single tectonic episode it rather represents a complex sequence of successive tectonic stages which produced a number of intra continental deformation zones with changing sometimes opposing lateral oblique and convergent kinematics in the canadian arctic archipelago north and ne greenland and svalbard the interaction between the continental plates especially in combination with the development of transform faults resulted onshore in the formation of several complex deformation zones and areas of eurekan deformation the eurekan deformation can be divided into two major tectonic stages the first phase in the early eocene was dominated by orthogonal compression in the west spitsbergen fold and thrust belt along the west margin of the barents shelf and contemporaneous sinistral strike slip tectonics along the wegener fault and on ellesmere island whereas the second phase in the late eocene was characterized by dextral strike slip and compression on ellesmere island and contemporaneous dextral transpression and transtension along the de geer fracture zone or hornsund fault complex between ne greenland and spitsbergen

cenozoic exhumation on the southwestern barents shelf estimates and uncertainties constrained from compaction and thermal maturity analyses abstract the barents sea is believed to have been influenced in most parts by cenozoic uplift and erosion episodes the rocks in the area are not currently at their maximum burial depth the exhumation of the sedimentary rocks has had large effects on rock physical properties and hydrocarbon maturation and migration the current study seeks to estimate exhumation from shale compaction and thermal maturity techniques and discuss its implications for hydrocarbon exploration in the uplifted barents sea area this study uses well logs and thermal maturity data together with widely distributed shot gather data along long offset seismic reflection lines the use of shale compaction techniques to estimate exhumation was focused particularly on the regionally preserved aptian albian kolmule formation and paleogene torsk formation shales normal compaction reference curves were established for these units in areas currently at their maximum burial depth e g sorvestsnaget basin and vestbakken volcanic province the results suggest widespread cenozoic exhumation throughout the southwestern barents sea the exhumation magnitudes increase towards east and northeast the average exhumation estimates from the three data sources range from 800 to 1400 m within the hammerfest basin 1150 1950 m on the loppa high 1200 1400 m on the finmark platform and 1250 2400 m on the bjarmeland platform the marked differences in glacial erosion from mass balance and average erosion estimates from the current study suggest a significant pre glacial uplift and erosion in the southwestern barents sea area the observed stratigraphy and presence of significant volumes of late oligocene middle miocene sediments in basins at the outer margin and increased erosion rates at the same time in source areas suggest that maximum burial in the southwestern barents sea may have occurred sometime during the oligocene or even earlier in the eocene the results from this study are useful input for modelling of source rock maturation generation migration and trapping of hydrocarbons in the area these results are also an important input for the prediction of more precise reservoir and seal rock properties in frontier areas away from the exploration wells and provide valuable knowledge for the use of interval velocities in the uplifted areas

structure and origin of terpenoid hydrocarbons in some german coals abstract hydrocarbon extracts of coal samples from major coal fields in west germany have been investigated by gas chromatography mass spectrometry gc ms the samples are of carboniferous and tertiary age and derive from limnic and paralic environments the saar district the ruhr area and the lower rhine basin differences in facies maturity and age reflected in the distribution patterns of the extracted alkylcyclohexanes an unexpected occurrence of cyclic diterpenoid hydrocarbons in some samples of carboniferous age has been found the tetracyclic compounds mainly show phyllocladane type structures and can serve as source indicators hydrocarbons obtained from chemical degradation of the macromolecular material of the samples also revealed phyllocladane type compounds which are normally associated to resins of modern and extinct familes of conifers origin and structural variations of this class of hydrocarbons are discussed in terms of maturity and palaeobotanical implications

coal related sources of organic contamination in sediments and water from the bierawka river poland abstract river sediments mixed with coaly material occur all along the length of the bierawka river poland to identify the origin of the coal in the sediment the coaly material was investigated by reflected light microscopy and rock eval pyrolysis and solvent extracts by gas chromatography mass spectrometry gc ms organic compounds dissolved in water were separated by solid phase extraction spe and analyzed by gc ms the results point to a kerogen iii source petrographic analyses confirm abundant coal charred and coked particles in the sediments vitrinite reflectance varied between 0 66 0 80 r r without any large spatial variation the coaly particles have different sources generally the primary origin of coal particles is from coal processing and the dumping the ash with unburned coal particles from a glass factory near the river source later this material was redeposited along the entire river course in addition hard coal processing crushing washing features are visible in larger coal pieces a second source of coaly organic matter is a coal waste dump at szczyglowice where intensive erosion of steep slopes has delivered copious amounts of organic matter into the river the mixing of this organic matter with that from the glass factory is clearly identified on a ternary diagram pah distributions also show differences between sections the coal particle input from the waste dump increased the relative content of naphthalene relative content downstream as in the coal waste 4 5 ring pahs predominate in the sediments the pyrogenic origin of pahs and aromatic compounds such as methylbiphenyls and dibenzofurane in the sediment is indicated by diagnostic pah ratios burned particles were identified petrographically the river water contains only 2 3 ring pahs possibly of industrial origin or leached from coal particles in the river sediments

3d seismic analysis of karstified interbedded carbonates and evaporites lower permian gipsdalen group loppa high southwestern barents sea abstract this paper presents a detailed seismic analysis of a hitherto undescribed permian succession interpreted to consist of interbedded anhydrite and carbonate from the northern flank of the loppa high western barents sea the fafner succession forms a locally restricted transgressive unit down dip on the rotated loppa high it is subdivided into four seismic sequences each interpreted to be composed of a basal transgressive anhydrite overlain by highstand carbonates fafner seismic sequences 2 and 3 include well developed buildup complexes which in map view form polygonal patterns analysis of attribute maps indicates that the fafner succession is overprinted by two dissolution systems related to two prominent events of subaerial exposure creating numerous paleo sinkholes breccia pipes and collapsed composite cavern systems the stratigraphical position of the fafner succession below the mid sakmarian artinskian bjarmeland group and above the top orn unconformity resembles that of the lower permian gipshuken formation on spitsbergen and the fafner succession is thus regarded as its offshore equivalent

magnetic pore fabric analysis a rapid method for estimating permeability anisotropy summary the average orientation and fabric anisotropy of interconnected pore spaces in sandstones is derived from magnetic pore fabric analysis a new technique which measures the anisotropy of magnetic susceptibility ams of samples impregnated with a magnetic suspension in magnetic pore fabric analysis the permeable part of the porous network consisting of pore bodies connected by pore throats is rendered magnetically susceptible ams directly yields the average elongation direction of pore bodies and offers a simple way to investigate the effect of pore shape anisotropy on petrophysical parameters such as hydraulic and electrical conductivity ams derived pore fabric of sandstones of moderate diagenetic state is compared to permeability anisotropy measured directly on the same specimens for any one sample the orientation of the two tensors and their representation ellipsoids correlate closely the preferred orientation of interconnected pores facilitates fluid flow parallel to the direction of pore elongation and causes the observed anisotropy of permeability axial ratios of the two anisotropy ellipsoids correlate less closely but show a trend of proportionality compared to the time consuming measurement of directional permeabilities magnetic pore fabric analysis may therefore provide a rapid way to estimate the orientation and to a lesser extent the degree of permeability anisotropy in porous sandstones the analysis of six specimens extracted from a large homogeneous block sample proves the accuracy and reliability of the method in five fluvial sandstone samples maximum permeability and pore elongation are roughly parallel to the palaeocurrent direction therefore magnetic pore fabric analysis can also be used to study the relationship between permeability pore fabric and sedimentary structures

a stable carbon isotope and biological marker study of polish bituminous coals and carbonaceous shales abstract biological marker and carbon isotopic compositions of coals and carbonaceous shales from the upper carboniferous strata of the upper silesian uscb lower silesian lscb and lublin lcb coal basins were determined to assess depositional conditions and sources of the organic matter n alkane sterane and isoprenoid distribution and carbon isotope ratios are consistent with an origin from higher plants in some cases pristane phytane pr ph ratios of carbonaceous shales roof and floor shales are 29 stereoisomers typical but not conclusive of higher plant origin carbonaceous shales exhibit a wider range of sterane composition suggesting local significant input of algal organic matter significant amounts of benzohopanes and gammacerane are present in some coals although benzohopanes are present at least in small amounts in samples from many different environments they have been reported to occur most commonly in marine environments the present study seems to provide the first example where benzohopanes have been reported in significant amounts in terrestrial organic matter gammacerane is abundant in rocks or sediments deposited in carbonate or highly saline marine environments the finding of high gammacerane concentrations in the coals expands the depositional settings in which it has been observed and questions its utility as an independent indicator of hypersaline carbonate environments stable carbon isotope composition of coals and type iii kerogen in carbonaceous shales as well as correlation of stable carbon isotope composition of saturated and aromatic hydrocarbons in carbonaceous shales from both the uscb and the lscb indicate terrigenous origin bitumens are always co genetic with associated coals and kerogens isotopic data reveal that sofer s genetic classification of oils is not applicable to organic matter in coals

first investigation of quartz and calcite shape fabrics in strained shales by means of x ray tomography abstract we document the evolution of the 3d fabric of shale along a km long strain gradient in the jaca basin southern pyrenees spain with respect to the distance from a thrust samples were collected in the cleavage free domain at the onset of the pencil cleavage domain within the pencil cleavage domain and within the slaty cleavage domain by combining high resolution x ray computed tomography xct and energy dispersive x ray spectroscopy eds the morphology and the shape preferred orientation spo of thousands of quartz grains calcite grains and pores was studied in the least deformed samples quartz and calcite display mean foliation parallel to bedding with comparable dispersion in the pencil cleavage domain quartz foliation still follows the bedding while calcite foliation is mostly governed by cleavage in the slaty cleavage domain calcite shows a much better organization with foliation parallel to cleavage mimicking closely the pore fabric by contrast the quartz shape fabric is much less defined scattered between bedding and cleavage planes this suggests that quartz grain act as rigid marker in the ductile matrix while calcite grain orientation is governed by dissolution precipitation processes

erroneous coal maturity assessment caused by low temperature oxidation previous work carried out on different outcrop coals from the french massif central revealed abnormally high tmax values which initially were attributed to high temperature oxidising fluids this increase in tmax which was exclusively observed for medium to low volatile bituminous coals rr 1 5 was accompanied by a very clear exponential like decrease of the hydrogen index hi together with an increase in the oxygen index oi with the aim of checking the possibility that this rise in tmax could simply be caused by weathering a few mature coal samples rr 1 4 were experimentally oxidised at rather low temperatures 110 125 and 150 c and for durations of up to 6 5 month then the oxidation residues were subjected to rock eval 6 pyrolysis and to vitrinite reflectance measurements these experiments effectively reproduce the geochemical changes displayed by the naturally altered coals thus supporting the hypothesis that the previously studied natural alteration process could have been ultimately caused by weathering the observed artificial oxidation path could be divided into two stages i a strong decrease in hi and an increase in oi and ii a constant hi value and a slow rise in oi the increase in tmax seems related to the transition between the first and the second stages this behaviour of hi and oi during artificial oxidation suggests that these two rock eval derived indices can be practically used to detect a moderate and even a low oxidation degree finally if one ignores the constancy of the vitrinite reflectance values all along the oxidation path the decrease of hi and the concomitant increase of tmax mimic a thermal evolution pathway

the autocorrelation function an image processing tool for fabric analysis abstract the use of the autocorrelation function acf is proposed as a method for fabric and or strain analysis its chief purpose is to extend fabric analysis to fine grained materials such as clays micrites etc or to materials where the determination of individual grain shapes is tedious or impossible the main advantage of the method is that no segmentation of the image prior to analysis is necessary in other words any bias associated with identifying grain boundaries and the like is avoided in as much as the recognition of grains or grain boundaries is a matter of scale the acf can be used without loss of generality whenever the grain size is small in comparison with the size of the analysed area the method is computer based it requires a scanner for the digitization of the images and sufficient storage space and computing power for digital image processing the method uses half tone images as input these can be obtained from thin sections acetate peels polished surfaces photographic negatives or positives etc the acf is a two dimensional function that is related to the average shape that occurs in the fabric it is scaled with respect to the original image and allows simultaneous analysis of small and large features the acf enables a a quantitative description of the fabric in general terms b an efficient grain size determination and c if strain is a valid interpretation of the fabric the derivation of the finite strains in the plane of observation in the first part of the paper the acf method is introduced by way of a few numerically generated fabrics and compared to other methods of fabric and strain analysis in the second part an application to three samples of experimentally deformed solnhofen limestone is demonstrated

architectural elements and bounding surfaces in fluvial deposits anatomy of the kayenta formation lower jurassic southwest colorado abstract three well exposed outcrops in the kayenta formation lower jurassic near dove creek in southwestern colorado were studied using lateral profiles in order to test recent regarding architectural element analysis and the classification and interpretation of internal bounding surfaces examination of bounding surfaces within and between elements in the kayenta outcrops raises problems in applying the three fold classification of allen 1983 enlarging this classification to a six fold hierarchy permits the discrimination of surfaces intermediate between allen s second and third order types corresponding to the upper bounding surfaces of macroforms and internal erosional reactivation surfaces within the macroforms examples of the first five types of surface occur in the kayenta outcrops at dove creek the new classifications is offered as a general solution to the problem of description of complex three dimensional fluvial sandstone bodies the kayenta formation at dove creek consists of a multistorey sandstone body including the deposits of lateral and downstream accreted macroforms the storeys show no internal cyclicity neither within individual elements nor through the overall vertical thickness of the formation low paleocurrent variance indicates low sinuosity flow whereas macroform geometry and orientation suggest low to moderate sinuosity the many internal minor erosion surfaces draped with mud and followed by intraclast breccias imply frequent rapid stage fluctuation consistent with variable seasonal monsonal ephemmeral flow the results suggest a fluvial architecture similar to that of the south saskatchewan river through with a three dimensional geometry unlike that interpreted from surface studies of that river

cenozoic erosion and the preglacial uplift of the svalbard barents sea region abstract the creation of the huge fans observed in the western barents sea margin can only be explained by assuming extremely high glacial erosion rates in the barents sea area glacial processes capable of producing such high erosion rates have been proposed but require the largest part of the preglacial barents sea to be subaerial to investigate the validity of these proposals we have attempted to reconstruct the western preglacial barents sea our approach was to combine erosion maps based on prepublished data into a single mean valued erosion map covering the whole western barents sea and consequently use it together with a simple airy isostatic model to obtain a first rough estimate of the preglacial topography and bathymetry of the western barents sea margin the mean valued erosion map presented herein is in good volumetric agreement with the sediments deposited in the western barents sea margin areas and as a direct consequence of the averaging procedures employed in its construction we can safely assume that it is the most reliable erosion map based on the available information by comparing the preglacial sequences with the glacial sequences in the fans we have concluded that 1 2 to 2 3 of the total cenozoic erosion was glacial in origin and therefore a rough reconstruction of the preglacial relief of the western barents sea could be obtained the results show a subaerial preglacial barents sea thus during interglacials and interstadials the area may have been partly glaciated and intensively eroded up to 1 mm y while during relatively brief periods of peak glaciation with grounded ice extending to the shelf edge sediments have been evacuated and deposited at the margins at high rates the interplay between erosion and uplift represents a typical chicken and egg problem initial uplift is followed by intensive glacial erosion compensated by isostatic uplift which in turn leads to the maintenance of an elevated and glaciated terrain the information we have on the initial tectonic uplift suggests that the most likely mechanism to cause an uplift of the dimensions and magnitude of the one observed in the barents sea is a thermal mechanism

current challenges and future developments in magnetic fabric research abstract magnetic fabrics are used extensively as proxies for mineral fabrics and to correct paleomagnetic data and have been proposed to quantify pore fabrics today s understanding and interpretation of magnetic anisotropy benefits from decades of carefully observing anisotropic mineral and rock properties establishing and testing empirical relationships between magnetic and mineral fabrics and developing models to quantify aspects of anisotropy each advance was preceded by some puzzling observations i e data that could not be explained based on the models available at the time e g oblique or inverse fabrics or lithology dependent anisotropy strain relationships these observations led to numerous experimental and numerical techniques designed to characterize magnetic fabrics and determine their origin despite the successful application of magnetic fabrics in many structural and tectonic problems there are still phenomena and measurements that cannot be explained based on today s magnetic fabric theory with the purpose of fostering future development i will touch on three main areas where i see challenges in magnetic fabric research 1 experimental characterization of magnetic anisotropy including the non uniqueness of reported tensors and non linearity 2 anisotropy modelling and defining the carrier minerals and origin of the magnetic fabric 3 selection of adequate sets of anisotropy tensors to correct paleomagnetic data the description of the challenges presented here will hopefully help define directions for future research inform those that are new to anisotropy and advance our field

interpretation of anisotropy of magnetic susceptibility fabric of ignimbrites in terms of kinematic and sedimentological mechanisms an anatolian case study abstract a study of the neogene low aspect ratio kizilkaya ignimbrite in the calc alkaline central anatolian volcanic province turkey has been carried out using the anisotropy of magnetic susceptibility ams technique on 46 sites irm hysteresis loops and curie temperature analysis indicate that magnetite is the main carrier of the magnetic signal in the ignimbrite the shape of the ams ellipsoids varies widely from site to site and the anisotropy is commonly low we review the data processing used in the literature on the ams of ignimbrites to calculate principal directions or to evaluate the quality of the results and we develop various simple techniques data filtering and contouring procedures in order to more accurately define the axis or symmetry of the ams fabric there is no simple relationship between the shape of the ams ellipsoids and the shape of the petrofabric ellipsoids similarly there is no direct relationship between magnetic and kinematic axes our results show that the source of the measured magnetic signal in these rocks is a complex result of various contributions including shape anisotropy of free and fixed magnetic crystals shape ams crystallization of magnetic grains on all surfaces and discontinuities during cooling of the ignimbrite distribution anisotropy and alteration by hydrothermal and meteoric water particular attention is paid to the interpretation of the ams stereoplots departing from the standard fabric of sedimentary rocks formed under unidirectional flow in order to explain these non standard ams fabrics we discuss their possible origin 1 in analytical and mineralogical terms instrumental artifact pollution by xenoclasts mineralogical inversion of the susceptibility axes secondary mimetic fabric and 2 in terms of sedimentological mechanisms rheology depositional processes in the present state of knowledge we conclude that due to the physico chemical complexity of the magnetic source the ams signal should be used and interpreted with care when attempting to decipher the sedimentological or rheological processes occurring in moving pyroclastic flows on the other hand ams has it greatest potential when used in conjunction with other techniques and when a large number of sampling sites and specimens is used

assessment of hydrocarbon source rock potential of polish bituminous coals and carbonaceous shales abstract we analyzed 40 coal samples and 45 carbonaceous shale samples of varying thermal maturity vitrinite reflectance 0 59 to 4 28 from the upper carboniferous coal bearing strata of the upper silesian lower silesian and lublin basins poland to evaluate their potential for generation and expulsion of gaseous and liquid hydrocarbons we evaluated source rock potential based on rock eval pyrolysis yield elemental composition atomic h c and o c and solvent extraction yields of bitumen an attempt was made to relate maceral composition to these source rock parameters and to composition of the organic matter and likely biological precursors a few carbonaceous shale samples contain sufficient generation potential pyrolysis assay and elemental composition to be considered potential source rocks although the extractable hydrocarbon and bitumen yields are lower than those reported in previous studies for effective type iii source rocks most samples analysed contain insufficient capacity for generation of hydrocarbons to reach thresholds required for expulsion primary migration to occur in view of these findings it is improbable that any of the coals or carbonaceous shales at the sites sampled in our study would be capable of expelling commercial amounts of oil inasmuch as a few samples contained sufficient generation capacity to be considered potential source rocks it is possible that some locations or stratigraphic zones within the coals and shales could have favourable potential but could not be clearly delimited with the number of samples analysed in our study because of their high heteroatomic content and high amount of asphaltenes the bitumens contained in the coals are less capable of generating hydrocarbons even under optimal thermal conditions than their counterpart bitumens in the shales which have a lower heteroatomic content

magnetic pore fabric analysis verification through image autocorrelation the pore fabric of sandstones is studied by impregnating porous samples with a magnetic suspension ferrofluid and subsequently measuring their anisotropy of magnetic susceptibility ams similar to the use of natural ams for estimation of grain fabric we determine average orientation and shape anisotropy of pore bodies in three dimensions this new approach overcomes restrictions of previous methods of pore structure characterization the interpretation of ams in terms of pore fabric anisotropy is tested by comparison with pore shape observed in thin section an image analytical technique is used to derive statistically the elongation direction of digitized pore cross sections by computing the two dimensional autocorrelation function we obtain section ellipses reflecting average pore shape and orientation combination of ellipses of three mutually perpendicular images leads to fabric ellipsoids comparable to ams comparison of the two anisotropies shows a close correspondence between the principal axis directions of ams and fabric ellipsoids owing to the bedded nature of the samples the ellipsoids are of oblate shape with minimum axes perpendicular to bedding however even small anisotropies within the bedding plane can be detected successfully axial ratios of ams and fabric ellipsoids correlate closely if rock sample ams is corrected for pore directional scattering the method represents a powerful tool to analyze pore fabric of sedimentary rocks and to study its effects on petrophysical properties

late mesozoic cenozoic exhumation history of northern svalbard and its regional significance constraints from apatite fission track analysis the late mesozoic cenozoic was a time of profound tectonic activity in the arctic with incipient spreading in the arctic ocean baffin bay labrador sea and north atlantic as well as the northward movement of the greenland microplate leading to collision and deformation in greenland arctic canada and svalbard eurekan orogeny it is however still unclear how northern svalbard situated at the northwestern edge of the barents shelf was affected by these processes furthermore northern svalbard has been proposed to have been a cretaceous cenozoic sediment source to surrounding regions because it lacks a post devonian sedimentary cover when erosion took place and how that related to the tectonic history of the arctic is yet unresolved in order to reconstruct the erosion history of northern svalbard we constrained its thermal evolution using apatite fission track aft thermochronology our data reveal aft ages between 62 5 and 214 10 ma recording late mesozoic early paleogene exhumation our data show that northern svalbard was emergent and experienced erosion from the early jurassic and presumably through the cenozoic although total exhumation was restricted to 6 km pronounced exhumation took place during jurassic cretaceous time probably linked to the extensional tectonics during the opening of the amerasian basin arctic ocean in contrast cenozoic ocean basin formation and the eurekan deformation did not cause significant erosion of northern svalbard nonetheless aft data show that late cretaceous early paleocene fault related exhumation affected some parts of northern svalbard fault zones were reactivated due to the reorganization of arctic landmasses during an early phase of the eurekan deformation which implies that this episode commenced 20 m y earlier in svalbard than previously understood

palynology and depositional environments of the middle late triassic anisian rhaetian kobbe snadd and fruholmen formations southern barents sea arctic norway abstract the middle to upper triassic series in the norwegian barents sea represents an important target for hydrocarbon exploration however the dating and correlation of these rocks are problematic due to the scarcity of age diagnostic macrofossils lateral facies variation and the overall thickness of the succession palynology has proven to be a useful dating tool but further work is necessary to improve the zonal resolution particularly for the upper triassic series the current paper presents a detailed palynostratigraphy of the middle upper triassic succession in four exploration wells 7120 12 2 7228 2 1s 7 1a and 9 1s drilled in the hammerfest and nordkapp basins eleven informal palynological zones are described from the stratigraphic interval spanning the kobbe snadd and fruholmen formations which constitute regionally significant hydrocarbon source and reservoir rock facies the results of this study contribute to a higher resolution palynostratigraphy for the middle to upper triassic strata of the southern barents sea sbs and an improved correlation with the stratigraphy of the svalbard archipelago palynofacies data for the succession presented here for the first time indicates depositional environments ranging from fluvio deltaic to offshore marine

from isolated buildups to buildup mosaics 3d seismic sheds new light on upper carboniferous permian fault controlled carbonate buildups norwegian barents sea abstract carbonate buildups are a common feature of many ancient carbonate platforms and were especially abundant during the palaeozoic our present understanding of buildup distribution and the ability to better predict their location is however hampered by the fact that maps of buildups rarely show evidence of widespread spatial organisation and indeed their distribution often appears chaotic a previously unrecognized pattern of buildup distribution has been revealed by three dimensional 3d seismic data recently acquired from the loppa high norwegian barents sea here syn rift carboniferous permian buildups are not isolated but are instead linked into a mosaic of laterally extensive ridges the buildups location is controlled by the intersection of three trends of syndepositional faults systematic organisation of buildup height width density and external form across the study area appears to have been controlled by changes in accommodation space driven by differential subsidence the buildups were remarkably long lived and developed over an interval of 35 ma despite this longevity buildup location remained relatively static and true to the underlying pattern of basement faults indicating that their progradation was likely restricted by a combination of factors including limited highstand production their depositional relief

the occurence of unusual c27 and c29 sterane predominances in two types of oman crude oil abstract two types of oman crude oils reveal unusual sterane distributions type a which is the more common 74 examples is characterised by a predominance of c 29 iso and normal steranes and generally none or only very low relative concentrations of rearranged steranes the triterpanes are characterised by the predominance of the c 29 17 h 21 h norhopane over the c 30 17 h 21 h hopane and non predominant c 20 c 30 tricyclic terpanes the c 29 steranes of this type of crude were not derived from the c 29 sterols of land plant origin frequently proposed as the source of c 29 steranes since there is good geological evidence that these crudes were generated from a pre cambrian source rock a geological period when land plants did not exist the type b crude oil 11 known examples is characterised by a strong predominance of c 27 iso normal and rearranged steranes relatively lower concentrations of 17 h 21 h hopanes and relatively high concentrations of c 20 c 30 tricyclic terpanes the remarkably different biomarker characteristics of these crude oils imply that the organisms active in the depositional environment of the respective source rocks were significantly different

wavelet transform a future of rock fabric analysis abstract although twenty years ago fabric was defined as the complete spatial and geometrical configuration of all those components that make up a deformed rock fabric was mainly synonymous with lattice preferred orientation very little attention has been paid to the multi scale geometrical and spatial relationships of the rock components fabric quantification in terms of size shape orientation and location at all scales is now performed in two dimensions using anisotropic wavelets as a first example the wavelets are applied to the famous colour plate of sander and the results compared to his axial distribution analysis applied to the k feldspars of a rock section from the sidobre granite pluton montagne noire france the wavelet analysis shows i alignment of grains resulting from mechanical interactions between grains and shows that shearing occurred within the crystalline frame ii preferred grain orientation the classical grain shape fabric parallel to the overall mineral lineation and iii small tensional domains elongate perpendicular to the lineation infilled by the residual melt just before total crystallisation attesting to the stretching nature of the mineral lineation the future of rock fabric analysis will come from new steps in understanding the processes acting during fabric development along with a further development of wavelet analysis using high resolution three dimensional fabric data

the pristane n heptadecane ratio as an indicator for recognition of hydrocarbon migration effects a simple scheme is proposed for type iii kerogen source rocks which uses pristane n heptadecane concentration ratios for recognition of hydrocarbon expulsion effects within the maturity interval 0 82 1 03 rm this scheme can be applied from gas chromatography data routinely obtained by most petroleum geochemistry studies in exploration exploration of this scheme to oil prone type ii source rocks appears very promising

biogenic methane generation in the degradation of eastern australian permian coals abstract hydrocarbons extracted from one sydney basin coal have a distribution of aromatic and aliphatic hydrocarbons consistent with a high degree of biodegradation as previously demonstrated for bowen basin coals on the same basis hydrocarbons from two other coals from the sydney basin are less biodegraded and display an additional minor series of alkylaromatic degradation products all these degradation reactions generate co2 which on biogenic reduction to ch4 is reservoired in association with the permian coal seams of the sydney and bowen basins australia variations in access to oxygenated waters nutrients and micro organisms are held to be largely responsible for the extent of biodegradation of coal hydrocarbons and for the reduction of co2