geochemical characteristics and hydrocarbon generation modeling of the jurassic source rocks in the shoushan basin north western desert egypt abstract the shoushan basin is an important hydrocarbon province in the western desert egypt but the origin of the hydrocarbons is not fully understood in this study organic matter content type and maturity of the jurassic source rocks exposed in the shoushan basin have been evaluated and integrated with the results of basin modeling to improve our understanding of burial history and timing of hydrocarbon generation the jurassic source rock succession comprises the ras qattara and khatatba formations which are composed mainly of shales and sandstones with coal seams the toc contents are high and reached a maximum up to 50 the toc values of the ras qattara formation range from 2 to 54 wt while khatatba formation has toc values in the range 1 47 wt the ras qattara and khatatba formations have hi values ranging from 90 to 261 mghc gtoc suggesting types ii iii and iii kerogen vitrinite reflectance values range between 0 79 and 1 12 vrr rock eval t max values in the range 438 458 c indicate a thermal maturity level sufficient for hydrocarbon generation thermal and burial history models indicate that the jurassic source rocks entered the mature to late mature stage for hydrocarbon generation in the late cretaceous to tertiary hydrocarbon generation began in the late cretaceous and maximum rates of oil with significant gas have been generated during the early tertiary paleogene the peak gas generation occurred during the late tertiary neogene

macroporosity and infiltration in blanket peat the implications of tension disc infiltrometer measurements little is known about the processes of infiltration and water movement in the upper layers of blanket peat a tension infiltrometer was used to measure hydraulic conductivity in a blanket peat in the north pennines england measurements were taken from the surface down to 20 cm in depth for peat under four different vegetation covers it was found that macropore flow is a significant pathway for water in the upper layers of this soil type it was also found that peat depth and surface vegetation cover were associated with macroporosity and saturated hydraulic conductivity the proportion of macropore flow was found to be greater at 5 cm depth than at 0 10 and 20 cm depth peat beneath a sphagnum cover tends to be more permeable and a greater proportion of macropore flow can occur beneath this vegetation type functional macroporosity and matrix flow in the near surface layers of bare peat appear to have been affected by weathering processes comparision of results with rainfall records demonstrates that infiltration excess overland flow is unlikely to be a common runoff generating mechanism on blanket peat rather a saturation excess mechanism combined with percolation excess above much less permeable layers dominates the runoff response copyright 2001 john wiley sons ltd

heat flow during the carboniferous and mesozoic of the northwest german basin the temperature history of the northwest german basin has been reconstructed using a one dimensional computer model that accounts for compaction related changes of physical rock properties depth temperature and maturity of organic matter maturity has been modelled by empirically relating vitrinite reflectance to time temperature history heat flow values for the mesozoic and carboniferous have been obtained by matching measured and computed vitrinite reflectance for mesozoic samples agreement between measured and computed maturity can be achieved with a heat flow between 37 and 50 mw m2 0 9 and 1 2 hfu there is no systematic areal variation carboniferous samples are matched best at heat flows between 70 and 96 mw m2 1 7 and 2 3 hfu corresponding to geothermal gradients between 50 and 80 c km depending on lithology and compaction areal variation follows patterns subparallel to the structural grain of the variscan orogeny mesozoic heat flow is compatible with heat flow in stable platform areas carboniferous heat flow and its geotectonic setting are best in agreement with present day back arc areas underlain by continental crust

high thermal maturity in the lower saxony basin intrusion or deep burial abstract the lower saxony basin lsb is situated at the southern rim of the northern permian basin the most important hydrocarbon bearing province in europe in its southern part areas of high thermal maturation up to 6 rr occur which were previously explained as being caused by magmatic intrusions of turonian to santonian age that affected carboniferous to lower cretaceous rocks in this area 2d numerical basin modelling was carried out in order to reconstruct the temperature histories along two parallel n s trending seismic sections along these sections new data about maturity distribution and temperature history were obtained by vitrinite reflectance measurements and apatite fission track analysis for the areas with highest maturity values low coalification gradients were established which agree well with earlier published data on wells further towards the west this new information does not support previous hypotheses on high heat flows from magmatic intrusions even if lateral heat transport is taken into account instead comparisons with a recently published map of the subsurface structure of the lsb indicate that maturity distribution may be closely related to major tectonic structures deep burial of individual structures of the lsb which are bordered by deep e w to ese wnw trending faults is further suggested by a rapidly increasing thicknesses of preserved cretaceous strata towards the south and b structural restoration of one of the seismic sections to achieve a fit between measured and calculated palaeo temperature and vitrinite reflectance data deep burial of carboniferous source rocks during cretaceous time has to be assumed due to an inversion phase in the early and middle upper cretaceous major amounts of sediment were removed and further uplift occurred in tertiary times in contrast the northern part of the lsb experienced maximum burial and temperatures during tertiary times

a comparison of burial maturity and temperature histories of selected wells from sedimentary basins in the netherlands sedimentary basins in the netherlands contain significant amounts of hydrocarbon resources which developed in response to temperature and pressure history during mesozoic and cenozoic times quantification and modelling of burial maturity and temperature histories are the major goals of this study allowing for a better understanding of the general geological evolution of the different basins as well as petroleum generation all major basins in the netherlands encountered at least one time of inversion and therefore moderate to high amounts of erosion in order to determine the amount of inversion the basins have experienced a 1d study was performed on 20 wells within three basins west netherlands central netherlands and lower saxony basins new vitrinite reflectance values were obtained and existing data re evaluated to gain a good data base the burial histories of six wells two for each studied basin are presented here to demonstrate the differences in basin evolution that led to their present shape and petroleum potential the permo triassic subsidence phase can be recognized in all three basins but with varying intensity in the jurassic the basins experienced different relative movements that culminated in the cretaceous when the influence of the inversion caused erosion of up to 2 500 m most wells show deepest burial at present day whereas the timing of maximum temperature differs significantly springer verlag 2007

the role of fission track dating in discrimination of provenance determination of single crystal ages by fission track dating analysis of zircons and subordinately apatites within a detrital heavy mineral assemblage together with frequency distribution and radial plot analysis of the measured ages permits identification of different age modes synopses are presented of published fission track provenance studies in north central victoria northeastern tasmania barbados the rockall trough the english wealden mexico utah and the central alps from authors

mechanism of crystal redistribution in a sheet like magma body constraints from the nosappumisaki and other shoshonite intrusions in the nemuro peninsula northern japan processes of crystal separation in a magma heavily laden with crystals without phase change are investigated from observations on frozen magma systems nosappumisaki and other shoshonite intrusions in the nemuro peninsula japan for which the origin of the crystals and the initial conditions are well constrained the nosappumisaki intrusion is 120 m in thickness and extends for more than 1 5 km it exhibits a wide range of lithological variation principally as a result of crystal redistribution after intrusion crystals in each lithology can be clearly divided into two kinds according to their composition and texture those present before the intrusion of the magma phenocrysts and those that crystallized in situ after intrusion from the vertical change in mode and size of phenocrysts it is shown that 1 augite phenocrysts were rapidly deposited with little overgrowth after intrusion by significant coagulation or clustering on a time scale of more than a few years and 2 plagioclase phenocrysts definitely denser than the melt but concentrated in the upper level floated by counter flow of massive deposition of augite phenocrysts these results indicate that in a magma heavily laden with crystals of a few millimeters in size 20 vol crystal crystal and crystal melt interaction play an important role in the separation of crystals from the host melt

geothermal history and petroleum generation in the norwegian south viking graben revealed by pseudo 3d basin modelling abstract hydrocarbon exploration in the norwegian south viking graben 57 45 60 15 n began in the late 1960s and has now entered a mature phase a map based pseudo three dimensional 3d basin modelling study is performed in order to unravel regional trends in hydrocarbon generation and expulsion and to evaluate the remaining potential of this mature petroleum province generation and expulsion from all major source rock horizons in the area the draupne heather hugin and sleipner formations is simulated using a pseudo 3d model comprising 36 isochronous geological events the map based pseudo 3d model is built from 1d models combined with subsurface and source rock quality maps hydrocarbon expulsion from the middle and upper jurassic source rocks in the area occurred in two major phases the first phase lasted from palaeocene to middle miocene with peak oil and gas expulsion during the early miocene the second quaternary phase of expulsion which supplied 11 and 13 of all oil and gas respectively is related to increased subsidence rates during this period a total of 74 109 sm3 oil and 8 2 1012 sm3 gas has been expelled in the area the frigg area in the north is with 2 9 1012 sm3 gas expelled the most gas prone area and the greater balder area seems to be the most oil prone area with 17 109 sm3 oil expelled the lower syn rift section of the upper jurassic draupne formation dominated oil expulsion 54 of all expelled oil whilst the heather formation dominated gas expulsion with 37 of all gas expelled model predictions were successfully applied to explain the fill and secondary alteration history of the greater balder area norway the modelling supports the draupne formation origin of the oils in the greater balder area as well as the presence of oils deriving from multiple charge phases found in correlation studies based on the modelled cumulative volumes expelled and estimates for in place volumes in the area generation accumulation efficiencies gaes of 1 01 1 05 for oil and 9 67 12 89 for gas have been estimated for the south viking graben in light of comparisons with other petroleum systems and critical evaluation of the elements of the petroleum systems the estimated gaes should be regarded as encouraging for further exploration of the area

activity along the osning thrust in central europe during the lateglacial ice sheet and lithosphere interactions abstract the osning thrust is one of the major fault systems in central europe with a length of approximately 115 km it underwent a polyphase tectonic evolution in the mesozoic that ranged from extensional movements in the jurassic to reverse faulting and thrusting during inversion in the late cretaceous a series of complex metre scale faults and related fold structures are developed within the upper pleistocene alluvial aeolian complex of the upper senne 1 km away from the thrust the faults dip towards the north and show offsets in a range of several decimetres growth strata indicate a two fold evolution of the structures the faults began as normal faults and were later transformed into reverse faults which resulted in the formation of small scale inversion structures with a typical harpoon shape glaciotectonics can be ruled out as the driving mechanism for these structures because new optically stimulated luminescence osl ages imply that the sedimentary succession was deposited during the late pleistocene between 29 3 2 9 ka and 13 1 1 5 ka at which time the ice margin was much further to the northeast we believe the inversion structures were caused by movement on the osning thrust due to generation of a forebulge of the late pleistocene weichselian ice sheet this led to normal faulting as a consequence of extension in the forebulge area during glaciation the osl ages for the normal fault related growth strata are in a range of 16 13 ka later reverse movements occurred during deglaciation due to the n s directed compressional stress field in northern germany numerical simulations of the deglaciation seismicity point to seismic events with a thrust mechanism in the study area between 15 5 and 12 3 ka bp although normal faulting is also possible in this time period numerous soft sediment deformation structures imply that movement on the osning thrust caused earthquakes with a significant magnitude in the autumn of 1612 an earthquake took place in this area it is very likely that this event is related to background seismicity on this fault although movement due to the influence of the ongoing glacial rebound in fennoscandia is also possible

the last phase of the storegga slide simulation of retrogressive slide dynamics and comparison with slide scar morphology the prehistoric storegga slide one of the world largest known submarine slides took place about 8200 years ago most likely the slide was triggered by an earthquake in a steeper slope area in the distal part of the slide the present day s morphology of the slide area indicates that major parts of the slide took place as a sequential failure process spreading successively from the far end to the present shelf edge numerical simulations illustrating this retrogressive back stepping behaviour are presented for the last phase of the storegga slide as it reached today s upper headwall the applied rheological model is based on a bingham fluid with a history dependent yield strength and consistency

reactivated basement structures affecting the sedimentary facies in a tectonically quiescent epicontinental basin an example from nw switzerland abstract the jurassic deposits in the southern part of central europe accumulated in a shallow epicontinental sea and their deposition has usually been believed to have corresponded to a phase of tectonic quiescence neither on conventional seismic records nor in outcrops obvious indications of synsedimentary tectonics were found nonetheless subtle variations in lithofacies and thickness occur above faults in the crystalline basement in fact preexisting structures became reactivated in the jurassic during major extensional phases when the tethys and the north atlantic opened this reactivation led to differential subsidence and or to rotation of fault bounded blocks but the sediments were deformed mainly flexurally as vertical movements in the basement were dissipated by triassic salt thus the depositional area was morphologically differentiated into swells and depressions in siliciclastic muddy environments swells were characterized by hardbottoms and hiatus beds depressions were filled by distal tempestites and gravity deposits in carbonate settings reefs nucleated on swells marls and muds were deposited in depressions many of them gravity deposits reactivation of faults occurred only during short episodes and was not synchronous throughout the study area and reactivation of individual faults was episodic and probably controlled by the palaeostress field and the faults orientation reactivation of deep rooted faults is also documented by hydrothermal activity which led to vein mineralization and alteration of minerals today exposed in nearby basement units the chronostratigraphic ages of the hydrothermal processes coincide with phases of enhanced subsidence during the sinemurian aalenian bajocian bathonian and oxfordian in turn facies changes of the sedimentary cover should be useful to predict basement structures when no seismic records are available

evolution of the lower saxony basin abstract the lower saxony basin is a 300 km long and 65 km wide late jurassic and early cretaceous trough which parallels the northern margin of the rhenish massif this basin became inverted during the senonian and paleocene the lower saxony basin is the most important oil province of germany past production amounts to 200 10 6 t of oil 1 5 10 9 bbl the lower saxony basin is superimposed on the late carboniferous variscan foredeep basin and the frontal structures of the variscan fold belt during the permian to middle jurassic the area formed part of the northwest european basin differential subsidence of the lower saxony basin was initiated during the late jurassic and persisted till albian time this involved reactivation of permo carboniferous fracture systems by divergent wrenching a major aptian deep seated laccolith is evident in the western part of the lower saxony basin during the senonian and paleocene sinistral convergent wrenching induced uplift of the basin floor and folding of its sedimentary fill the margins of the inverted lower saxony basin are thrust over the adjacent stable platform areas the differential subsidence of the lower saxony basin can be related to a period of major crustal extension in the north sea rift basin inversion coincides with important orogenic events in the alpine system and is thought to have been induced by intra plate compressional stresses

soil conditions and slope stability in the ormen lange area abstract the ormen lange gas field is located in 850 1100 m water depth in the slide scar of the enormous storegga slide this slide occurred about 8200 years ago and left steep and high scarps above and below the planned field development area today s stability of these scarps has been a major concern for the field development work this paper gives an overview of soil investigations evaluation of potential trigger mechanisms and stability analyses performed to demonstrate adequate conditions the area under consideration is large with a limited number of geotechnical borings and integration of geological geophysical and geotechnical information was required to develop a geotechnical model of the area the stress history and the soil conditions are strongly influenced by rapid deposition during glacial periods by the loss of overburden from the storegga slide and glacial loading along the shelf edge natural and project induced triggering sources with potential for generation of renewed slide activity were evaluated with respect to magnitude and location and possible influence area relative to the major scarps stability analyses were carried out for critical sections of the scarps under gravity loading and under combination of gravity and potential triggering sources applying drained analyses for long term gravity loading and undrained analyses considering gravity combined with short term load effects project induced load effects like weight of equipment and rockfills anchor loads and effects of drilling and production activities were found to have insignificant effect on the large scale stability of the headwalls and local surficial slope failure can be handled by adequate engineering and lay out with respect to natural triggering sources it was concluded that an extremely strong earthquake with a very low probability of occurrence is the only realistic mechanism for triggering of new slides in the ormen lange area

fluid inclusion technique for determining maximum temperature in calcite and its comparison to the vitrinite reflectance geothermometer theory laboratory experiments and empirical observation suggest that many aqueous fluid inclusions in calcite reequilibrate during overheating and therefore some homogenization temperatures t h record a temperature close to the maximum reached by the rock this characteristic suggests that aqueous fluid inclusions in calcite can be used to establish maximum temperature t peak to test this hypothesis we have compiled fluid inclusion t peak mean random vitrinite reflectance r m and present day t peak from 46 diverse geologic systems that have been at t peak from 10 4 to 10 6 yr present t peak ranged from 65 to 345 c t h modes and means ranged from 59 to 350 c and r m data ranged from 0 4 to 4 6 spanning the temperature and thermal maturity range associated with burial diagenesis hydrothermal alteration and low grade metamorphism plots of t h and t peak data for systems thought to be currently at maximum temperature demonstrate close agreement between t h and present t peak in sedimentary basins although caution should be applied the relation suggests that t h of aqueous fluid inclusions in calcite may be a useful measure of maximum temperature this study also compares t h to mean random vitrinite reflectance r m to offer further support for the use of t h as a measure of t peak and to provide a better understanding of r m t h correlates well with r m and results in a curve similar to r m vs t peak calibrations determined by other workers the strong correlation correlation coefficient r 0 93 between t peak and r m in these systems suggests that maximum temperature is the major control on thermal maturation

numerical simulation of the thermal maturation oil generation and migration in the songliao basin northeastern china abstract the discovery of the giant daqing oil field in the songliao basin led to the realisation of the significant petroleum potential of non marine basins in order to reconstruct the basin evolution and oil formation an integrated organic geochemical basin modelling study along a regional transect across the songliao basin was conducted it provided a regional heat flow evolution model and revealed post orogenic or late syn orogenic maturation in the central depression and pre orogenic maturation in the southeast uplift zone kinetic parameters of petroleum generation for the lacustrine source formations are the basis for the simulation of oil generation and migration in the songliao basin using the principle activation energy peaking at 54 kcal mol and a pre exponential factor of about 4 2 1027 ma 1 the simulation obtained a relatively good match with the measured transformation ratios the qingshankou formation in the west and east central depressions constituted the major source in the basin major oil generation migration and accumulation occurred during the early tertiary in the west central depression the generated oils migrated upwards into the yaojia formation followed by the updip migration into the daqing anticline and towards the local structural high along the west slope in contrast the oil migration in the east central depression was dominated by the downward movement from the lower member of the qingshankou formation followed by the updip migration towards the caoyang anticline the simulated oil accumulations are in good agreement with discovered oil fields implying a potential application of the model for prediction and evaluation of new exploration targets in the basin

seafloor instabilities and sediment deformation processes the need for integrated multi disciplinary investigations abstract in this paper we present the current practice of investigations of seafloor instabilities and deformation processes based on extensive research conducted over the last years which sets the scene for future research activities in this field the mapping of the continental margins and coastal areas with ever increasing resolution systematically reveals evidence of instabilities and deformation processes both active and palaeo features in order to properly assess the hazards and risks related to these features an integrated and multi disciplinary approach is essential but challenging such an approach consists of combining field data geophysics geology sedimentology geochemistry and geotechnical data with numerical simulations constrained by results from laboratory data as such it is of paramount importance to build a common knowledge base and understanding that unify these disciplines into more complete and conceptual models constrained by all the data we review the status of this integrated approach adapted to palaeo landslides e g storegga ana vesteralen and recent deformations finneidfjord nice gulf of guinea allowing to identify gaps in our knowledge at these sites by reviewing these case studies one can conclude that each case remains highly site specific in which both the regional and local geological tectonic settings have a distinct effect of the type of instability or deformation taking place or that can take place our knowledge on the actual triggers remains poorly constrained and there is even ambiguity for historic landslides e g finneidfjord also our knowledge of the preconditioning factors is incomplete there is a general lack of geotechnical data both in situ and from laboratory and therefore modelling the dynamics e g rheology of the instabilities relies on a number of assumptions rather than facts in addition excess pore pressure and its evolution is one of the key parameters driving instabilities despite this fact in situ excess pore pressure is rarely measured or monitored much work remains to be done to relate and integrate geotechnical data with geophysics e g through inversion and rock physical models in order to obtain additional quantitative information from the sub surface but also with respect to partial saturation free gas hydrate and pore pressure behaviour or lithologies it is of critical importance to be able to identify the different processes which can lead to hazardous situations which include establishing recurrence intervals timing and frequencies through event recognition and age control and magnitudes so that proper mitigation measures can be developed in this perspective the smaller scale instabilities deserve much attention as there are many instances where such features had far reaching consequences for society e g nice finneidfjord in that perspective human interferences e g exploitation drilling blasting loading must be one of the factors that should be taken into consideration

modelled palaeo temperature on voring offshore mid norway the effect of the lower crustal body abstract the voring area offshore mid norway has a complex geological history has experienced several extensional phases and was significantly influenced by the break up of the north atlantic we have modelled a cross section over the voring basin aiming to 1 reconstruct the basin evolution in a realistic way and 2 to investigate the heat flow and temperature history in the basin for the modelling we used the following tectonic events the opening of the basin during the permo triassic an event during the middle to late cretaceous and an event in the late cretaceous paleocene the theoretical effects of the lithospheric stretching are depending on the palaeo water depths of the area we present a prediction of the palaeo water depth and a sensitivity analysis of the influence of the palaeo water depth on the estimated beta factors in the area a lower crustal high velocity body found in the area is often interpreted as magmatic underplating related to the break up of the norwegian sea we show the temperature history calculated by models that were run with and without assumption of underplating by a magmatic body emplaced during the early tertiary the observed vitrinite reflectance in the voring area is best explained by numerical calculations of the vitrinite reflectance without a magmatic underplating our conclusion is that the lower crustal body is not related to magmatic underplating or to significant sill intrusions the body may consist of older mafic rocks or a mixture of old continental crust and mafic intrusions

controls of soil pipe frequency in upland blanket peat 1 soil pipes were surveyed in 160 british blanket peat catchments using consistent application of ground penetrating radar soil pipes were found in all catchments the mean frequency of piping was 69 per kilometer of surveyed transect land management moorland gripping appears to exert the most important control on hillslope pipe frequency in blanket peats management practice in peatlands may therefore induce more rapid subsurface erosion carbon loss and landform denudation via enhanced preferential flow topographic position is also important with topslopes having greater pipe frequencies than footslopes followed by midslopes with lowest frequencies slope gradient however is not a significant factor in controlling blanket peat pipe frequency i propose that peat structural properties inherited from the way a blanket peat develops on a hillslope strongly control pipe network development this is manifested in the way slope position appears to control pipe frequency aspect appears not to influence pipe frequency in blanket peats except that it does play a weak role in catchments with annual precipitation 1500 mm here southwesterly facing slopes tend to have more frequent piping

topographic controls upon soil macropore flow macropores are important components of soil hydrology the spatial distribution of macropore flow as a proportion of saturated hydraulic conductivity was tested on six humid temperate slopes using transects of tension infiltrometer measurements automated water table and overland flow monitoring allowed the timing of and differentiation between saturation excess overland flow and infiltration excess overland flow occurrence on the slopes to be determined and related to tension infiltrometer measurements two slopes were covered with blanket peat two with stagnohumic gleys and two with brown earth soils none of the slopes had been disturbed by agricultural activity within the last 20 years this controlled the potential for tillage impacts on macropores the proportion of near surface macropore flow to saturated hydraulic conductivity was found to vary according to slope position the spatial patterns were not the same for all hillslopes on the four non peat slopes there was a relationship between locations of overland flow occurrence and reduced macroporosity this relationship did not exist for the peat slopes investigated because they experienced overland flow across their whole slope surfaces nevertheless they still had a distinctive spatial pattern of macropore flow according to slope position for the other soils tested parts of slopes that were susceptible to saturation excess overland flow e g hilltoes or flat hilltops tended to have least macropore flow to a lesser extent for the parts of slopes susceptible to infiltration excess overland flow the proportion of macropore flow as a component of infiltration was also smaller compared with the rest of the slope the roles of macropore creation and macropore infilling by sheet wash are discussed and it is noted that the combination of these may result in distinctive topographically controlled spatial patterns of macropore flow copyright 2008 john wiley sons ltd

magnetic properties of howardite eucrite and diogenite hed meteorites ancient magnetizing fields and meteorite evolution abstract the remanent magnetism and other magnetic properties of four howardites kapoeta petersburg le teilleul and eet 87503 two eucrites sioux county and pca 82502 and three diogenites shalka johnstown and eet 79002 have been investigated the dominant carrier of magnetic properties is low nickel kamacite present to the extent of 3 5 by weight in petersburg and 0 1 1 in the others a wide range of remanent magnetization nrm intensities characteristics and behaviour during alternating field and thermal demagnetization is observed two common features are scattered directions of nrm between meteorite subsamples and anomalous behaviour of nrm direction and intensity during demagnetization all the meteorites show evidence of a primary nrm acquired during an early evolutionary and some acquired secondary nrm the heterogeneous nrm with which anomalous demagnetization appears to be associated implies magnetization of constituent fragments of the meteorite prior to and no remagnetization after final meteorite assembly it is tentatively proposed that the primary magnetizing field was of internal origin in the parent body and that thermoremanent magnetization occurred when the body cooled after differentiation the coherent magnetic fabric observed in all but two of the heds was most probably imparted at the time of final assembly of the meteorites

numerical modelling of burial and temperature history as an approach for an alternative interpretation of the bramsche anomaly lower saxony basin the lower saxony basin germany is one of the several sedimentary basins within the central european basin system in its southwestern part anomalously high maturity of organic matter has been observed to reach 4 5 vrr in upper jurassic and lower cretaceous sedimentary rocks in an area which coincides with a magnetic and a positive gravimetric anomaly this anomaly was often interpreted as the consequence of a deep seated igneous intrusion the so called bramsche massif however results obtained from calibrated numerical modelling are not in accordance with this scenario instead a burial by approximately 4 km of now eroded cretaceous rocks was revealed to be the probable cause for the anomaly data and modelling results from six boreholes and two pseudo wells support this view

on the origin of the southern permian basin central europe abstract a detailed study of the structural and stratigraphic evolution of the southern permian basin during latest carboniferous to early jurassic times supported by quantitative subsidence analyses and forward basin modelling for 25 wells leads us to modify the conventional model for the rotliegend zechstein development of this basin the late permian early jurassic tectonic subsidence curves are typical for a permian to early triassic extensional stage that is followed by thermal subsidence however a purely extensional model is extremely problematic because active faulting during this time is minor and generally hard to document using inverse techniques to model the subsidence curves we quantitatively show that a significant component of late permian and triassic tectonic subsidence can be explained by thermal relaxation of early permian lithospheric thinning and by delayed infilling of paleo topographic depressions that developed during the early permian in this interpretation stephanian autunian wrenching resulted in thermal destabilisation of the lithosphere deep fracturing of the crust disruption and erosion of its sedimentary cover and regional uplift of the area of the future southern permian basin upon termination of wrench tectonics and associated volcanism towards the end of the autunian the southern permian basin began to subside in response to thermal contraction of the lithosphere the evolving basin was isolated from the world oceans and had subsided possibly up to some 700 m below their level at the beginning of upper rotliegend sedimentation after catastrophic flooding of this paleo topographic depression at the beginning of the zechstein changing sea level sedimentation and subsidence rates remained essentially in balance although the effects of triassic rifting overprinted parts of the southern permian basin its overall subsidence pattern persisted well into the jurassic in contrast to the remainder of the southern permian basin permian and triassic crustal extension contributed significantly to the subsidence of the polish trough

new information on the thermal history of the southwestern lower saxony basin northern germany based on fission track analysis the southwestern part of the lower saxony basin lsb is characterized by gravity and magnetic anomalies and by an extremely high thermal maturity of organic matter this was for many years attributed to a late cretaceous intrusion but actually deep burial is being debated the complex thermal history of the area has been studied by fission track analysis zircon data provide evidence for widespread hydro thermal activity during the permian and upper jurassic lower cretaceous apatite ages indicate a major cooling event in the mid cretaceous 89 72 ma reflecting the time of inversion of the lsb during the cretaceous the cooling of the basin centre was rapid compared to the basin margins apatite fission track ages from borehole samples which are recently within the upper part of the apaz indicate a young heating of the sedimentary sequences until present

biodegradation of oil in uplifted basins prevented by deep burial sterilization biodegradation of crude oil by bacterial activity which has occurred in the majority of the earth s oil reserves is known to reduce greatly the quality of petroleum in reservoirs for economically successful prospecting for oil it is therefore important to understand the processes and conditions in geological formations that lead to oil biodegradation although recent studies speculate that bacterial activity can potentially occur up to temperatures as high as 150 degrees c refs 3 4 it is generally accepted that effective petroleum biodegradation over geological timescales generally occurs in reservoirs with temperatures below 80 degrees c ref 2 this appears however to be at odds with the observation that non degraded oils can still be found in reservoirs below this temperature here we compile data regarding the extent of oil biodegradation in several oil reservoirs and find that the extensive occurrence of non biodegraded oil in shallow cool basins is restricted to those that have been uplifted from deeper hotter regions of the earth we suggest that these petroleum reservoirs were sterilized by heating to a temperature around 80 90 degrees c during deep burial inactivating hydrocarbon degrading organisms that occur in the deep biosphere even when such reservoirs are subsequently uplifted to much cooler regions and filled with oil degradation does not occur implying that the sterilized sediments are not recolonized by hydrocarbon degrading bacteria

provenance and thermal history of the franciscan accretionary complex constraints from zircon fission track thermochronology the franciscan accretionary complex of california contains large belts of sediments that were subducted to depths of 10 to 30 km metamorphosed under high pressure and low temperature conditions and later returned to the surface reconnaissance zircon fission track ft data 21 samples place constraints on the sedimentary provenance thermal history and or exhumation history of various franciscan units in a transect across the northern coast ranges through mendocino pass metagraywacke samples from the valantine springs formation of the franciscan eastern belt experienced maximum temperatures tmax ranging from 250 to 310 c zircon ft and previously reported apatite ft data indicate that parts of the western eastern and eastern central belts cooled at about 100 70 ma from 300 c to 100 c considering the low paleogeothermal gradient of roughly 9 c km during franciscan subduction these rocks were apparently uplifted and exhumed from 30 to 10 km depth at this time one sample from the eyler mountain sequence in the northwestern diablo range similarly shows tmax 310 c and major cooling at 100 70 ma this uplift and exhumation may have reflected accelerated accretion at the base as well as the front of the franciscan wedge accompanied by extensional thinning at shallower levels as a result of massive sediment influx into the franciscan trench from the sierra nevada magmatic arc in the northern coast ranges the western part of the central belt and the coastal belt experienced lower tmax probably 200 c and retain source area detrital zircon ft ages burnt hills terrane samples in the diablo range also experienced tmax 230 c and retain detrital ages the detrital single grain age patterns from these areas are compatible with those expected from the sierra nevada magmatic arc and its country rocks this is consistent with derivation of franciscan sediments from arc terranes in california and provides no particular suggestion that these parts of the franciscan are highly allochthonous paleogene coastal belt sandstones also yield detrital ages compatible with derivation from the sierra nevada but also include early tertiary zircon populations compatible with reconstructions suggesting these sandstones were sourced partly from the idaho batholith

a zero damage model for fission track annealing in zircon a zircon fission track annealing model is calculated on the basis of annealing experiments from the literature with induced tracks in decay event damage free zircon samples empirically derived parallel and fanning equations for this zero damage model yield an excellent fit to the data with the fanning model providing slightly better statistical parameters a comparison between annealing models with fanning iso annealing lines but different decay event damage densities reveals that annealing temperatures and closure temperatures for the estimated partial annealing zone are highest for the zero damage model compilations of existing geologic constraints on the zircon partial annealing zone on one hand and the zircon closure temperature on the other show that these constraints do not or only partly overlap with curves of proposed models for the zircon partial annealing zone and closure temperature this finding is consistent with the fact that the annealing behavior of zircon from long duration temperature evolutions is increasingly influenced by the accumulated decay event damage zircon samples of young age or low u content show a behavior closest to the predictions of the zero damage model and are in the predicted range of published models with low decay event damage density for thermal events of more than 10 myr duration however constraints from field studies show marked differences from proposed partial annealing zone boundaries of the zero or low damage models the applicability of the zero damage model is threefold 1 it predicts correct closure temperatures in the case of very rapid cooling across the partial annealing zone where basically no decay event damage is accumulated 2 it predicts an uppermost boundary for complete annealing of a mixture of zircon components of different age as found in sedimentary samples and in this case may be used as a thermometer 3 it represents an important reference for the establishment of a more comprehensive model of zircon fission track annealing that also includes the influence of decay event damage for such a model two different equations are discussed however additional detailed experimental and field data are needed for a more robust annealing model that includes the influence of decay event damage annealing

integrated geothermal modeling on different scales in the northeast german basin geothermal modeling is an important part of large scale basin studies based on a new 3d structural model of the northeast german basin the present day regional geothermal field is modeled range and regional trend of the modeled temperature values are in agreement with the published data due to the high spatial resolution the calculated temperature distribution provides additional information with respect to areas where no measured data is available the results are used as input and boundary parameters for small scale models of geothermal energy production in general in many regions not enough data is available to define all necessary physical or chemical parameters for modeling in this context data obtained from the large scale model help to constrain unknown parameters subsequently the small scale model is used to simulate various production schemes focusing on enhanced predictions with respect to the possible lifetime of such installations the simulation results also show the need for elaborated models if reliable predictions of the temperature evolution are required

stress transfer in the storegga area offshore mid norway abstract the recently discovered large gas field ormen lange within the storegga submarine slide area offshore mid norway poses important questions as to the origin of these large submarine slides and their possible implications in terms of the safety of the development and the production in this respect the present study was initiated with the main objective of investigating the possibility of stress transfer as triggering mechanism for multiple earthquake occurrence and hence for the storegga submarine slide ca 8200 years before present bp stress changes following different scenario earthquakes along the selected faults in the area are modeled and computed for a number of cases using the coulomb failure criterion we demonstrate the possibility of large earthquakes triggering multiple ruptures along neighbouring fault segments the combined effect of the co seismic slip and strong ground shaking due to a large earthquake m 7 accompanied by the stress transfer on the optimally oriented normal fault planes which are analogous to the slide scar may have played an important role for the triggering of the storegga submarine slide

triassic rifts and facies patterns in western and central europe the triassic evolution of western and central europe was governed by regional crustal extension that induced the subsidence of a complex network of grabens and troughs these formed an integral part of the arctic north atlantic and the tethys central atlantic gulf of mexico rift and rift wrench systems which in the course of the mesozoic and cenozoic developed into major break up axes of pangea

geological partial annealing zone of zircon fission track system additional constrains from the deep drilling miti nishikubiki and miti mishima abstract fission track ft analysis of zircon from rhyolite and sandstone samples of ministry of international trade and industry miti nishikubiki and miti mishima boreholes has given additional constraints on the temperature range of the zircon partial annealing zone zpaz over a geological time scale the advantages of these samples are the following 1 they have been exposed to a stable temperature for 1 million years and 2 it is possible to obtain data at successive temperatures ages and confined track lengths were measured in samples from depths of 3 5 5 6 km with a current environmental temperature of 223 c at the deepest track lengths in samples below 200 c are still long and ft ages are compatible with their sedimentary ages showing no evidence of annealing for a heating duration of 1 million years samples at 205 c seem to yield shortened tracks as a result of annealing because of a low number of zircon crystals only four track lengths were measured for the deepest sample whose mean length was shortest among analysed samples these data are consistent with previous results from ultra deep boreholes

thermobarometric data from a fossil zircon partial annealing zone in high pressure low temperature rocks of eastern and central crete greece abstract a fossil partial annealing zone of fission tracks in zircon is described from high pressure low temperature hp lt rocks of the phyllite quartzite unit pq on the island of crete greece correlation of regional trends in fission track age populations with independent thermobarometric and microstructural data and with new experimental annealing results allows a calibration of this low temperature thermochronological method to a degree hitherto not available from other field examples the zircon fission track ft ages of samples from the pq across crete range from original detrital signature through reduced to completely reset the annealing is the result of a single heating period related to the hp lt metamorphism with near peak temperatures lasting for only a few million years some time between 24 1 and 20 1 ma in eastern crete where rocks have experienced temperatures of 300 50 c and pressures of 0 8 0 3 gpa zircon ft ages range from 414 24 to 145 10 ma ages above 300 ma occur mostly near the east coast of the island in rocks which have not been heated to above ca 280 c and probably represent a pre variscan source track lengths are already indicative of a substantial annealing at this temperature most of the zircon ft ages from eastern crete scatter within error around the stratigraphic age samples with apparent zircon ft ages significantly younger than the depositional age are only observed in areas where temperatures exceeded ca 320 c towards the west a sudden decrease to very young ages ranging from 17 2 to 18 1 ma reflects a complete resetting at ca 350 c short tracks however are still observed throughout the central and western part of the island ages are consistently below 22 ma thermobarometric data for this area indicate maximum temperatures of 400 50 c and pressures of 1 0 3 gpa only samples from western crete which have been exposed to 400 50 c show exclusively long tracks consequently the high temperature limit of the zircon partial annealing zone zpaz appears to be between 350 and 400 c a significant influence of elevated confining pressure on the stability of fission tracks in zircon is ruled out by the results of annealing experiments at 0 5 gpa and at different temperatures which fit the curves previously obtained by other authors at ambient pressure

natural long term annealing of the zircon fission track system around a granitic pluton we measured 24 ages and 14 length distributions of fission tracks in zircons separated from basement sandstones around a granitic pluton to investigate natural long term annealing behaviors of the zircon fission track zft system samples were collected from three cretaceous coherent units of the shimanto accretionary complex shikoku japan along an eastward traverse at distances of between 1 6 and 10 6 km from the intrusion contact of 15 ma takatsukiyama granite exposing about 5 km in diameter sampling was carried out around the expected position of the transition zone of track retention i e the fossil partial annealing zone fpaz based on previous regional zft age distributions approaching the contact original zft ages of 100 ma show a continuous reduction to 15 ma at 3 km distance their single grain age distributions accordingly change from widespread multimodal patterns reflecting provenance ages to unimodal ones characterizing the secondary heating by the granite intrusion mean and distributions of zft lengths also show notable variations within the fpaz as a result of mixing both preexistent tracks that were shortened by the miocene heating and unannealed ones having original long lengths that have been formed and accumulated after the cooling of the pluton these facts along with observed track segmentation and annealing anisotropy suggest that the shortening patterns of tracks in nature a heating duration of 105 106 years estimated from thermal modeling are indistinguishable from those previously demonstrated at laboratory timescales this basically validates the conventional approach of extrapolating laboratory based kinetic parameters to geologic timescales the observed fpaz and thermal modeling results in conjunction with laboratory heating data previously reported and recent constraints from an ultradeep borehole favor a relatively narrow temperature range for the partial annealing zone i e 230 to 330 c for a heating duration of 106 years

hydraulic conductivity in upland blanket peat measurement and variability a key parameter used in wetland hydrological and landform development models is hydraulic conductivity head recovery tests are often used to measure hydraulic conductivity but the calculation techniques are usually confined to rigid soil theory this is despite reports demonstrating the misapplication of rigid soil theory to non rigid soils such as peats while values of hydraulic conductivity calculated using compressible techniques have been presented for fenland peats these data have never to the authors knowledge been compared to such calculations in other peat types head recovery tests slug withdrawal were performed on piezometers at depths ranging from 10 cm to 80 cm from the surface on north pennine blanket peats results were obtained using both rigid and compressible soil theories allowing comparison of the two techniques compressible soil theory gives values for hydraulic conductivity that are typically a factor of five times less than rigid soil calculations hydraulic conductivity is often assumed to decrease with depth in upland peats but at the study site in the northern pennines it was not found to vary significantly with depth within the range of peat depths sampled the variance within depth categories was not significantly different to the variance between depth categories showing that individual peat layers did not have characteristic hydraulic conductivity values thus large lateral and vertical differences in hydraulic conductivity over short distances creates problems for modelling but may help account for the high frequency of preferential flow pathways within what is otherwise a low matrix hydraulic conductivity peat hydraulic conductivity was found to vary significantly between sampling sites demonstrating that hillslope or catchment scale variability may be more important than plot scale variability values for compressibility of the peats are also reported these generally decline with depth and also vary significantly between sampling sites there are implications for the way in which measurements of hydraulic conductivity and other properties of blanket peat are interpreted as the effects of environmental change in one part of a peat catchment may be very different to those in another

fire decreases near surface hydraulic conductivity and macropore flow in blanket peat many peatlands have been subjected to wildfire or prescribed burning but it is not known how these fires influence near surface hydrological processes macropores are important flowpaths in the upper layers of blanket peat and were investigated through the use of tension disc infiltrometers which also provide data on saturated hydraulic conductivity measurements were performed on unburnt peat u where prescribed burning had taken place 2years b2 4years b4 and 15 b15 years prior to sampling and where a wildfire w had taken place 4months prior to sampling where there had been recent burning b2 b4 and w saturated hydraulic conductivity was approximately three times lower than where there was no burning u or where burning was last conducted 15years ago b15 similarly the contribution of macropore flow to overall infiltration was significantly lower between 12 and 25 less in the recently burnt treatments compared to b15 and u there were no significant differences in saturated hydraulic conductivity or macropore flow between peat that had been subject to recent wildfire w and those that had undergone recent prescribed burning b2 and b4 the results suggest that fire influences the near surface hydrological functioning of peatlands but that recovery in terms of saturated hydraulic conductivity and macropore flow may be possible within two decades if there are no further fires

a two layer lithospheric compressional model for the tertiary uplift of the southern united kingdom reflection seismic records show that many of the mesozoic sedimentary basins of the southern united kingdom were compressed and uplifted inverted during the late cretaceous tertiary recent quantitative studies based on apatite fission track analysis and chalk porosity data show that uplift and erosion although concentrated in the inverted basins was regional and not limited to the recognized areas of crustal shortening inversion a two layer or heterogeneous model of lithospheric compression similar to two layer models of lithospheric extension may account for this pattern of uplift upper lithospheric shortening is accommodated by reverse movement on major reactivated extensional detachments causing inversion of pre existing basins pure shear shortening of the lower lithosphere is decoupled and may be laterally displaced from that in the upper lithosphere lower lithospheric shortening and thickening displaced from that in the upper lithosphere causes initial subsidence due to the submersion of cold dense lithosphere into the surrounding asthenosphere subsequent thermal re equilibration of the lower lithosphere may have generated the uplift without attendant crustal shortening witnessed by apatite fission track and chalk porosity data

source rock heterogeneity of the upper jurassic draupne formation north viking graben and its relevance to petroleum generation studies abstract the upper jurassic draupne formation in the north viking graben north sea has been studied to identify lateral and vertical variations in source rock characteristics and their effect on the timing of petroleum generation fourteen source rock samples from the western flank of the graben and five from the eastern flank were analysed using rock eval analysis microscopy open system pyrolysis gas chromatography and kinetic experiments two major organic facies with different petroleum generation characteristics were identified a stratigraphically higher thermally less stable facies corresponding to a type ii kerogen with hi hydrogen index values of 350 mg hc g toc and a stratigraphically lower more stable type ii iii facies with hi values

probabilistic and deterministic seismic hazard results and influence of the sedimentary more basin ne atlantic abstract seismic hazard assessments have been conducted for the ormen lange gas field in the norwegian sea on the flank of the more basin the study used logic tree based probabilistic methods combined with semi deterministic methods for hazard contributions from mapped faults and the hazard was computed in terms of peak ground acceleration pga and spectral acceleration the probabilistic seismic hazard results were complemented by deterministic modelling in 1d wave number integration and 2d finite difference crustal models the deterministic modelling first of all elucidated the shaking duration problem indicating that thick offshore sediment structures like the ones in the more basin may significantly extend the shaking duration of an earthquake the presence of sedimentary layers with large velocity contrasts are responsible for this observation and a conventional soil amplification analysis would not have revealed this phenomenon a modelling along similar lines as indicated in the present paper may be recommended in certain vulnerable situations and in geologic provinces with thick sedimentary layers with significant internal velocity contrasts even though large earthquakes most likely have occurred in the region during the postglacial period the study could not resolve if the huge storegga slide which occurred about 8100 yb was triggered by an earthquake

hydrological hotspots in blanket peatlands spatial variation in peat permeability around a natural soil pipe 1 measurements were made of the hydraulic conductivity k of peat around a natural soil pipe in a blanket bog this is the first investigation of decimeter scale variability in both vertical k and horizontal k in blanket peats which were found to be higher than indicated by previous research this information suggests that it may be appropriate to reconsider i the spatial sampling strategies employed to investigate subsurface flow in blanket peatlands and ii how field data are used to parameterize flow models critically there was spatial structure in the heterogeneity with a wedge of high k peat directly above the pipe forming a hydrological conduit between near surface peat and the perennially flowing pipe there was also significantly greater horizontal k parallel to the pipe s orientation compared with horizontal k perpendicular to the pipe determinations of the triaxial anisotropy of k undertaken for the first time in peat soils revealed substantial directional variations in k the k around the pipe peat interface was investigated however sample length dependency of k for peat samples precluded the investigation of a hypothesized low k skin around the pipe

quantitative hc potential evaluation using 3d basin modelling application to franklin structure central graben north sea uk abstract 3d basin modelling is now used by some oil companies for exploration purposes the potentiality of this tool is not fully expressed but it seems that it should become the core of the basin evaluation process in the near future in this paper the methodology of 3d basin modelling in a relatively mature area is presented this methodology is based on a four step process which includes 1 3d block building 2 gridding 3 backward modelling and 4 forward modelling these processes are illustrated through a case study performed on the franklin structure central graben north sea uk the main results of this study show that petroleum migration is a 3d process that cannot in this specific case be properly addressed by 2d basin modelling alone furthermore the global hydrocarbon mass balance only accessible by 3d modelling shows that only 2 of the total hydrocarbons generated by the source rocks are present in the main reservoir

modelling the petroleum generation and migration of the third member of the shahejie formation es3 in the banqiao depression of bohai bay basin eastern china abstract the mudstones in the third member of the shahejie formation es3 are the primary source rocks in the banqiao depression of bohai bay basin they are rich in organic matter with total organic carbon toc content up to 3 5 the sandstones in the es3 member are the deepest proven hydrocarbon reservoir rocks with measured porosity and permeability values ranging from 3 6 to 32 4 and from 0 01 md to 3283 7 md respectively one two and three dimensional basin modelling studies were performed to analyse the petroleum generation and migration history of the es3 member in the banqiao depression based on the reconstruction of the burial thermal and maturity history in order to evaluate the remaining potential of this petroleum province the modelling results are calibrated with measured vitrinite reflectance ro borehole temperatures and some drilling results of 63 wells in the study area calibration of the model with thermal maturity and borehole temperature data indicates that the present day heat flow in the banqiao depression varies from 59 8 mw m2 to 61 7 mw m2 and the paleo heat flow increased from 65 ma to 50 4 ma reached a peak heat flow values of approximately 75 mw m2 at 50 4 ma and then decreased exponentially from 50 4 ma to present day the source rocks of the es3 member are presently in a stage of oil and condensate generation with maturity from 0 5 to 1 8 ro and had maturity from 0 5 to 1 25 ro at the end of the dongying formation ed deposition 26 ma oil generation 0 5 ro in the es3 member began from about 37 ma to 34 ma and the peak hydrocarbon generation 1 0 ro occurred approximately from 30 ma to 15 ma the modelled hydrocarbon expulsion evolution suggested that the timing of hydrocarbon expulsion from the es3 member source rocks began from 31 ma to 10 ma with the peak hydrocarbon expulsion shortly after 26 ma secondary petroleum migration pathways in the es3 member of the banqiao depression are modelled based on the structure surfaces at 26 ma and present day respectively the migration history modelling results have accurately predicted the petroleum occurrences within the es3 member of the banqiao depression based on the calibration with drilling results of 10 oil producing wells one well with oil shows and 52 dry holes six favorable zones of oil accumulations in the es3 member of the banqiao depression are identified especially oil accumulation zones i and ii due to their proximity to the generative kitchens short oil migration distances and the presence of a powerful drive force

hydrological controls of surficial mass movements in peat peat deposits occur in areas where water logging is common large areas of blanket mire occur throughout the temperate and cold regions of the northern and southern hemispheres and are particularly extensive in the uk uplands mass movements of peat reported usually as peat slides and bog bursts have been well documented for over 150 years however the fundamental controls of this form of shallow instability are still poorly understood the aim of this paper is to review critically the available evidence linking peat hydrology and slope instability then using data from the north pennine uplands in northern england we examine the importance of rainfall macroscale drainage conditions and peat hydrological processes in initiating slope instability shear failure by loading buoyancy effects basal liquefaction and surface or marginal rupturing have all been proposed as potential failure mechanisms data from northern england demonstrate that hydrological processes are fundamental in determining the spatial and temporal occurrence of peat slides most instabilities are associated with convective summer thunderstorms although instances of rapid snowmelt and intense winter rainfall have also triggered these events all instabilities occur in association with distinct drainage features slides are initiated along natural drainage lines or in association with artificial drainage often brought about by mining activity or agricultural practices at the scale of the soil profile the special hydrological properties of peat in particular shallow water tables and low soil hydraulic conductivity offer important clues to failure mechanisms pore water pressures are generally low and vary little in the peat profile and throughout the year it is clear from observations of subsurface flow that significant volumes of runoff reach considerable depths in the soil macropores flow occurring in pores greater than 1 mm in diameter are important in delivering surface runoff to deeper parts of the profile and in some instances high pipe water pressures may develop these findings define several important hydrological controls for surficial mass movements in peat but the prospect of predicting the location and timing of such events is still a long way off

quantification of risks associated with seabed instability at ormen lange the ormen lange gas field is located within the slide scar of the enormous storegga slide that took place about 8200 years ago there are strong indications that the storegga slide generated a tsunami wave hitting the coastlines of norway scotland and the faeroes the headwalls of the storegga slide are steep and their safety factor against sliding could be low an extensive study was therefore performed to evaluate the probability for new submarine slides and their potential consequences results of the study showed that the 1st party and 3rd part risks associated with potential slide activity in the ormen lange area are negligible

a parametric study of tsunamis generated by submarine slides in the ormen lange storegga area off western norway tsunami generation by submarine slides have been a major concern in the risk assessment for the ormen lange gas field off western norway tsunamis are analysed with a numerical model supplemented by an analytical one both models show how slide extensions and slide dynamics influence the tsunamigenic potential for a large region several combinations of slide parameters were tested and the product of initial acceleration and the volume of the slide gave the best correlation with the maximum surface elevation for the near coastal domain

on the correlation between heat flow and crustal thickness abstract in this study the results of a search for correlation between terrestrial heat flow and the thickness of the earth s crust are presented the correlation is sought for separately in different categories of the tectonic formations considered these categories are defined by the thickness of the consolidated crust and also the degree of correspondence between the variations of the positions of the upper and lower boundaries of the consolidated crust along particular tectonic units the calculations show a definite correlation to exist between heat flow and moho depths in every category considered this correlation is positive for tectonic formations with thick crust and negative for those with normal and thinned crust it is found that the thinning of the crust with increasing heat flow results in one and the same correlational relationship for three different particular categories of platform structures which however have quite different thermal regimes this particular correlation appears to be stronger than any of the other correlational relationships obtained in this work a physical interpretation of this close correlation will be given in a subsequent paper

role of temperature and time on organic metamorphism geologic notes organic metamorphism kerogen to hydrocarbon transformation is a function of both temperature and exposure time the effect of temperature is exponential of that of time linear at very low temperatures 266 f 130 c the reaction proceeds at such a high rate that time also plays no important role the effect of time is noticeable in the range of 158 to 212 f 70 to 100 c where intermediate conversion rates prevail stopping the heating process termination of burial freezes the rate constant of the reaction and allows organic metamorphism to continue at a linear rather than exponential rate this effect is demonstrated with the help of a simple geologic model for the first example a source rock was subjected to continuous linear heating whereas for the second the heating was terminated at a certain temperature level the model was analyzed by using the oleum scale a modified lopatin approach

thermal maturity in the central european basin system schleswig holstein area results of 1d basin modelling and new maturity maps thermal maturity information has been compiled for one of the deepest parts of the central european basin system the schleswig holstein area in northern germany new vitrinite reflectance data were obtained and old data were evaluated from a total of 31 wells furthermore numerical 1d basin modelling was performed in order to interpolate extrapolate vitrinite reflectance data to base zechstein and base keuper for these two horizons maturity maps were finally compiled revealing large differences in present day thermal maturity within the basin for example vitrinite reflectance at base zechstein ranges from greater than 4 5 in the glueckstadt graben to less than 1 in the northern part of the study area highest thermal maturity of base keuper occurs in the west holstein trough and in the northern part of the glueckstadt graben the timing of maturation is greatly affected by the complex tectonic evolution of the area for six key wells distributed over the entire study area burial and temperature histories as well as evolution of maturity were evaluated using 1d basin modelling deepest burial and maximum temperatures occurred either during jurassic upper cretaceous or neogene times in these wells only some parts of the sedimentary package in schleswig holstein show a significant increase in maturity during the tertiary leading to additional hydrocarbon generation and entrapment

annealing kinetics of fission tracks in zircon an experimental study a series of laboratory annealing experiments on zircon fission tracks has been carried out under heating conditions of 350 750 c for 10 1 103 hr i e 4 5 min 40 days variation in the confined lengths of spontaneous fission tracks was determined using zircon grains from nisatai dacite the fading contours of normalized mean track length r on the arrhenius diagram showed as sets of straight lines we performed a series of model fittings called the parallel and fanning models in order to describe the decrease in r with increasing temperature or heating time the lowest temperature limit of the zircon partial annealing zone zpaz was defined as r 0 95 and the highest as r 0 4 which approximately corresponded to the total fading of surface tracks extrapolation of the results of the laboratory experiments to the geological timescale gives for a heating duration of 106 yr estimated values of the zpaz of 210 320 c 60 c 2 with the parallel model 190 350 c 50 c 2 with the fanning model critical temperature t0 and 170 390 c 50 c 2 with the fanning model t0 the temperatures of the zpaz decrease by 20 c for an annealing duration that is an order of magnitude longer because the estimated closure temperature of zircon fission track analysis approximately corresponds to the middle of the zpaz these results support the previously estimated closure temperature of 240 c by varying the etching time it was revealed that significant removal of radiation damage occurs at r 0 93

zircon and apatite fission track thermochronology of late carboniferous volcanic rocks of the ne german basin zircon and apatite fission track analyses from late carboniferous felsic volcanic rocks of the ne german basin halle area and friedland drilling reveal at least two major post emplacement thermal events after initial cooling at ca 300 ma the volcanic pile underwent a major thermal event at ca 200 ma that reached in most places ca 250 280 c and led to the new growth of clay minerals this event is recorded in the zircon fission track data and can be related to jurassic triassic rifting in europe another thermal event is recorded in the apatite samples at ca 100 ma a close correlation is observed between apatite fission track age texture and sample alteration coarse grained samples are stronger altered and have younger fission track ages hydrothermal alteration coupled with advective heating probably caused these upper cretaceous fission track ages the latter event can be related to block faulting and inversion of the european plate during the early stages of the alpine orogeny

application of ground penetrating radar to the identification of subsurface piping in blanket peat natural soil pipes are common and significant in upland blanket peat catchments yet there are major problems in finding and defining the subsurface pipe networks this is particularly important because pipeflow can contribute a large proportion of runoff to the river systems in these upland environments and may significantly influence catchment sediment and solute yields traditional methods such as digging soil pits are destructive and time consuming particularly in deep peat and only provide single point sources of information this paper presents results from an experiment to assess the use of ground penetrating radar gpr to remotely sense pipes in blanket peat the technique is shown to be successful in identifying most of the pipes tested in the pilot catchment comparison of data on pipes identified by gpr and verified by manual measurement suggests that pipes can be located in the soil profile with a depth accuracy of 20 to 30 cm gpr identified pipes were found throughout the soil profile however those within 10 20 cm of the surface could not be identified using the 100 or 200 mhz antennae due to multiple surface reflections generally pipes smaller than 10 cm in diameter could not be identified using the technique although modifications are suggested that will allow enhanced resolution future work would benefit from the development of dual frequency antennae that will allow the combination of high resolution data with the depth of penetration required in a wetland environment the gpr experiment shows that pipe network densities were much greater than could be detected from surface observation alone thus gpr provides a non destructive fast technique which can produce continuous profiles of peat depth and indicate pipe locations across survey transects copyright 2002 john wiley sons ltd

sediment yield and delivery in the blanket peat moorlands of the southern pennines in contrast to much previous research on blanket peat moorland which has concentrated upon studies of the form and causes of gully erosion this paper attempts to investigate sediment transport and to estimate both short term and long term sediment yields in such terrain the research was conducted on wessenden head moor to the west of huddersfield yorkshire where automatic stream sampling continued over a period of two years use of corrected rating curves ferguson 1988 provided a mean estimate of sediment yield over this period of 55 t km 2 yr 1 in addition an estimate of longer term sediment yield was derived from four reservoir sediment surveys in the wessenden valley total yield was 203 69 t km 2 yr 1 including an organic fraction of 38 82 t km 2 yr 1 stream sampling at three sites on shiny brook including headwaters and the outflow to the reservoir suggested that there is great temporal and spatial variability in mineral and organic inputs to the reservoirs although not excessive in gravimetric terms the low density of peat means that there is a serious erosion problem estimates of erosion rates for the peat gully network at shiny brook appear to confirm earlier evidence concerning the relatively recent occurrence of this erosion within the last two centuries

piping and pipeflow in a deep peat catchment abstract natural pipes are common in many upland blanket peats yet little is known about pipe network morphology or pipeflow processes most information on soil piping comes from the shallow peaty podzols of the welsh uplands where monitoring suggests that pipes may be important contributors to streamflow this paper presents information on piping and pipeflow from a deep upland blanket peat catchment in the pennine hills of northern england pipe outlets are found throughout the soil profile ranging from the underlying substrate at 3 m depth to pipes which are within a few centimetres of the surface mean pipe diameters range from 3 to 70 cm some pipes are over 150 m long slopes in the catchment are less steep than those usually associated with soil piping continuous flow records were obtained from 15 gauging sites on 8 separate pipes the pipeflow response from deep blanket peat was found to be different to that reported in the shallow peaty podzols of the welsh uplands the distinction between ephemeral and perennial pipe types does not appear to be useful within the deep pennine blanket peat response times from all of the pipes are short even from pipes deep within the peat at the same time pipes have a prolonged recession limb such that they maintain low flow for longer periods than most other runoff production processes within the catchment pipeflow contributes around 10 of the streamflow volume but can at times contribute up to 30 soil pipes may therefore be far more important in some upland peat catchments than previous work has hitherto suggested

ormen lange an integrated study for the safe development of a deep water gas field within the storegga slide complex ne atlantic continental margin executive summary abstract a great effort has been undertaken to investigate potential geohazards in relation to the development of the ormen lange gas field offshore mid norway the field is located in the scar left after the giant tsunami generating storegga slide which occurred roughly 8150 years ago and the slide risk has consequently received particular focus the studies have been multi disciplinary in character and have involved a number of companies universities and research institutions the results of the project have lead to a significant advance in our understanding of the storegga slide in particular and submarine slope instability in general and played an important role in the approval of field development by norwegian authorities this special issue comprises 26 individual contributions in addition to this representing the wide span of topics addressed in the project and this introductory paper gives a brief summary of their contents

development of recent chronologies and evaluation of temporal variations in pb fluxes and sources in lake sediment and peat cores in a remote highly radiogenic environment cairngorm mountains scottish highlands the use of stable pb isotope analyses in conjunction with recent 210pb and anthropogenic radionuclide chronologies has become a well established method for evaluating historical trends in depositional fluxes and sources of atmospherically deposited pb using archival records in lake sediment or peat cores such studies rely upon i simple radioactive disequilibrium between unsupported 210pb and longer lived members of the 238u decay series and ii well defined values for the isotopic composition of contaminant pb and indigenous pb in the study area however areas of high natural radioactivity can present challenging environments for such studies with potential complications arising from more complex disequilibria in the 238u decay series and the occurrence at local or regional level of anomalous ill defined stable isotope ratios due to the presence of elevated levels of radiogenic pb results are presented here for a study of a sediment core from a freshwater lake loch einich in the high natural radioactivity area of the cairngorm mountains of scotland 238u decay series disequilibria revealed recent diagenetic re deposition of both u and 226ra the latter resulting in a requirement to use a modified calculation to derive a 210pb chronology for the core confidence in the chronology was provided by good agreement with the independent 241am chronology but the 137cs distribution was affected by significant post depositional mobility in the organic rich sediment the systematics of variations in 230th 232th and stable pb isotope ratio distributions were used to establish the indigenous pb characteristics of the sediment the relatively high radiogenic content of the indigenous pb resulted in complications in source apportionment in particular during the 20th century with multiple natural and anthropogenic sources precluding the use of a simple binary mixing model consequently 206pb 207pb ratios in scottish moss samples from an archive collection were used to provide the input term for atmospheric deposition in order to establish historical trends in indigenous and anthropogenic pb fluxes a test of the accuracy of the derived pb fluxes was provided by analysis of a core from a nearby blanket peat deposit great moss independent atmospheric and basal inputs gave a complex distribution of 210pb in the peat but this did not affect calculation of a 210pb chronology once again the 210pb chronology was supported by the 241am distribution temporal trends in anthropogenic pb deposition derived for the loch einich sediment core were in generally good agreement with those for the great moss peat core other peat cores and some other lake sediment cores from northern scotland providing confidence in the use of the archive moss data to characterise atmospheric deposition however sustained input of pb to loch einich sediment at relatively high levels in the late 20th century after the regional decline in atmospheric pb deposition suggested that catchment derived pb is now a significant component of the depositional flux for loch einich

finite element analysis and ray tracing modeling of petroleum migration separate phase flow is the dominant transport mechanism for secondary migration of petroleum phases commonly two different methods are used for the modeling of separate phase flow full 3d modeling finite element analysis which leads to the physically best description but can only be performed on low resolution grids and flowpath modeling ray tracing which can be performed on high resolution grids but is based on simplified physical assumptions a new approach that integrates both methods allows a physically realistic description without losing any of the original geometric information this new approach cuts processing times considerably

unsaturated hydraulic properties of sphagnum moss and peat reveal trimodal pore size distributions in ombrotrophic peatlands the moisture content of the vadose zone acrotelm controls oxygen diffusion rates redox state and the turnover of organic matter whether peatlands act as sinks or sources of atmospheric carbon thus relies on variably saturated flow processes the richards equation is the standard model for water flow in soils but it is not clear whether it can be applied to simulate water flow in live sphagnum moss transient laboratory evaporation experiments were conducted to observe evaporative water fluxes in the acrotelm containing living sphagnum moss and a deeper layer containing decomposed moss peat the experimental data were evaluated by inverse modeling using the richards equation as process model for variably saturated flow it was tested whether water fluxes and time series of measured pressure heads during evaporation could be simulated the results showed that the measurements could be matched very well providing the hydraulic properties are represented by a suitable model for this a trimodal parametrization of the underlying pore size distribution was necessary which reflects three distinct pore systems of the sphagnum constituted by inter intra and inner plant water while the traditional van genuchten mualem model led to great discrepancies the physically more comprehensive peters durner iden model which accounts for capillary and noncapillary flow led to a more consistent description of the observations we conclude that the richards equation is a valid process description for variably saturated moisture fluxes over a wide pressure range in peatlands supporting the conceptualization of the live moss as part of the vadose zone