experimental study of fluid transport processes in the matrix system of the european organic rich shales i scandinavian alum shale abstract this contribution presents results from a laboratory study investigating the fluid gas water transport properties in the matrix system of the scandinavian alum shale the maturity of the organic matter of the shale samples ranged between 0 5 and 2 4 vitrinite reflectance vr r gas he ar ch 4 and water flow properties were determined at effective stresses ranging between 5 and 30 mpa and a temperature of 45 c the effects of different controlling factors parameters on the fluid conductivity including permeating fluid moisture content anisotropy heterogeneity effective stress pore pressure and load cycling were analyzed and discussed pore volume measurements by helium expansion were conducted under controlled in situ effective stress conditions on a limited number of plugs drilled parallel and perpendicular to bedding for alum shale the intrinsic permeability coefficients measured parallel and perpendicular to bedding 6 10 22 8 10 18 m 2 were within the range previously reported for other shales and mudstones permeability coefficients were strongly dependent on permeating fluid moisture content anisotropy effective stress and other sample to sample variations the intrinsic absolute permeabilities measured with helium were consistently higher up to five times than those measured with argon and methane permeability coefficients he ch 4 measured on a dry sample were up to six times higher than those measured on an as received sample depending on effective stress the effect of moisture on measured permeability coefficients became more significant as effective stress increased permeability coefficients he ch 4 measured parallel to bedding were up to more than one order of magnitude higher than those measured perpendicular to bedding parallel to bedding all samples showed a nonlinear reduction in permeability with increasing effective stress 5 30 mpa the stress dependence of permeability could be well described by an exponential relationship

chitinozoan graptolite and scolecodont reflectance as an alternative to vitrinite and pyrobitumen reflectance in ordovician and silurian strata anticosti island quebec canada because of the absence of vitrinite in lower paleozoic sediments the reflectance of pyrobitumen is used as an indicator of thermal maturation a new technique of preparing organic matter permits discrimination among types of zooclasts and solid bitumen including pyrobitumen and leads to more precise reflectance histograms studies of organic matter from ordovician silurian strata of anticosti island show that reflectance of zooclasts is different from that of solid bitumen and that each group of the following zooclasts chitinozoans graptolites and scolecodonts has a specific reflectance evolution path with increasing depth on a logarithmic scale the paths of the three groups of zooclasts are linear highly correlated and converging however reflectance of solid bitumen is not linear throughout the range studied solid bitumen becomes linear only where the reflectance is greater than 0 75 comparing the relations between zooclasts and solid bitumen with the vitrinite solid bitumen correlation in the literature suggests that a hypothetical vitrinite evolution line in the anticosti island basin should be subparallel with that of chitinozoans and graptolites but 0 4 0 8 lower in the 1 2 range however scolecodonts and vitrinite should have the same reflectance at 1 but scolecodont reflectance should be slightly 0 2 higher for a vitrinite reflectance of 2

a method for determining terrestrial heat flow in oil basinal areas abstract a method for determining the terrestrial heat flow has been studied in the oil gas basinal areas in japan to estimate the heat flow an available zone was selected from a geologic section observed in a well the selected zone is covered by many bottom hole temperatures sufficient to determine a reliable geothermal gradient the bottom hole temperature was converted into an equilibrium formation temperature mainly by using the simple equation obtained from the relations between bottom hole and reservoir temperatures the thermal conductivity of the zone was primarily determined by both the measurements of well core samples and the experimental relations of thermal conductivity to porosity of some specific rocks then the conductivity was adjusted to subsurface temperature by using the empirical equation deduced from the relations of thermal conductivities of materials to temperatures

absolute transports of mass and temperature for the north atlantic current subpolar front system the flow of subtropical waters carried into the northern north atlantic ocean by the north atlantic current subpolar front system nac spf is an important component of the meridional overturning circulation these waters become colder and denser as they flow through the subpolar region both by mixing with the colder subpolar waters and by atmospheric cooling the relative roles of these two processes remain to be quantified and the mechanisms driving lateral mixing need to be better understood to address those questions a new methodology is developed to estimate the mean absolute transports of mass and heat for the top 1000 dbar in the region of the nac spf for the time period 1993 2000 the transports are obtained by combining historical hydrography with isopycnal rafos float data from the area the mean absolute transport potential field shows an nac spf pipe defined by two bounding transport potential contours this pipe transports 10 0 6 3 5 sv sv 106 m3 s 21 top 1000 dbar from the subtropics into the eastern subpolar north atlantic in contrast to earlier studies the northward flowing nac follows a distinct meandering path with no evidence of permanent branches peeling off the current before reaching the northwest corner as the current enters the northwest corner it loses its tight structure and maybe splits into two or more branches which together constitute the eastward flow along the spf the eastward flow between the northwest corner and the mid atlantic ridge is not as tightly defined because of the meandering and or eddy shedding of the branches constituing the spf as the flow approaches the mid atlantic ridge it converges to cross above the charlie gibbs and faraday fracture zones the mean absolute temperature transport top 1000 dbar by the 10 sv pipe was estimated across 10 transects crossing the nac spf because the mean mass flux is constant in the pipe variations in the mean temperature transports result from lateral exchange and mixing across the pipe s side walls and from air sea fluxes across the surface of the pipe the nac spf current loses 0 18 6 0 05 pw on its transit through the region most of the loss occuring upstream of the northwest corner the heat loss is 10 times the corresponding heat lost to the atmosphere we conclude that cross frontal exchange induced by the steep meanders of the northward flowing nac is the main mechanism by which heat is lost along the current in the region between the tail of the grand banks and the mid atlantic ridge

molecular and isotopic compositions and origin of natural gases from cambrian and carboniferous lower permian reservoirs of the onshore polish baltic region natural gases from middle cambrian and carboniferous lower permian reservoirs of the onshore polish baltic region were studied for their molecular and stable isotope compositions the following gas species were analysed 12 13c in ch4 c2h6 c3h8 n c4h10 i c4h10 and co2 1 2h in ch4 14 15n in n2 and stable isotopes of all noble gases due to significantly different geological settings and genetic types of source rocks of eastern and western pomerania the molecular and isotopic compositions of natural gases of these two regions exhibit distinct differences hydrocarbon gases associated with oil accumulated in the middle cambrian reservoir of eastern pomerania were generated during low temperature thermogenic processes from a single source rock containing type ii kerogen at one phase of petroleum generation non associated hydrocarbon gases accumulated in the carboniferous mississippian and pennsylvanian lower permian rotliegend reservoirs of western pomerania originated during at least two phases of gas generation by thermogenic processes from mainly type iii kerogen and a small component of mixed type iii ii kerogen noble gases are in general heavily enriched in radiogenic and nucleogenic isotopes such as 4he 40ar and 21ne accumulated in the reservoirs weak contributions of mantle derived he and ne are observed radiogenic 4he 40ar ratios are higher than the average production rate ratio of about 5 for radiogenic 4he 40ar in crustal materials which might have been caused by a selective supply of 4he that is lighter than 40ar from crustal rocks or u th k ratio might be higher than the average in crustal block carbon dioxide from gases of both the western and eastern pomerania were mainly generated during thermogenic processes of transformation of organic matter although gases of western pomerania can contain an endogenic component molecular nitrogen from the eastern pomeranian natural gases was mainly generated during low temperature thermal transformation of organic matter and derived from nh3 and nh4 of crustal fluid whereas molecular nitrogen from western pomeranian natural gases contains a significant component from the destruction of organic matter at a higher maturity level which may have been caused by a high heat flux from the volcanic activity during late pennsylvanian early rotliegend ages and has a bigger component release from nh4 rich illites

light element distributions n b li in baltic basin bentonites record organic sources abstract distributions of nitrogen boron and lithium were studied in illite smectite from ordovician silurian k bentonites in the baltic basin these trace elements are linked to thermal maturation of organic matter creating fluid signatures that are distinct from those in regionally buried sediments the fluid chemistry is ideally recorded in authigenic illite within the k bentonite because b substitutes in tetrahedral sites of illite li in octahedral sites and n is fixed in the interlayers as nh 4 three nanometric size fractions of illite 10 among these size fractions relate mainly to changes in fluid composition during illite growth bentonite volcanic ash layers mark stratigraphic timelines while illitization of the bentonite k bentonite varies as a function of burial and tectonic temperature gradients in the central baltic basin bentonites were deposited across a carbonate platform near estonia grading to deep basin shales near denmark and poland compositional variations in illite reflect fluids from different sources high n illite 2000 ppm in the southwest basin transitions to high b 250 ppm and high li 100 ppm illite to the northeast these trends follow a thermal gradient decreasing from southwest 200 c to northeast 90 c isotope ratios of b and li show opposing trends in samples across this thermal gradient the bisotopes decrease from southwest to northeast 18 to 4 while li isotopes increase from 5 to 32 the cambrian alum shale a regional hydrocarbon source rock was studied as a potential source of b and li as more than 50 of its b and li was associated with organic matter with increasing thermal maturity illite 11b decreased from 0 to 13 while 7li increased from 20 to 5 these opposing trends are similar to those observed in the k bentonites this suggests that organic sources of n b and li dominate fluids in bentonites from the southwestern baltic basin whereas basement derived fluids dominate in the northeastern baltic basin these trace elements record paleofluid changes during illite crystal growth and can identify pathways of chemically distinct oil and gas related fluids

hydrocarbon generation potential and thermal maturity of coal and coaly mudstones from the eocene urahoro group in the kushiro coalfield eastern hokkaido japan abstract this study reveals the hydrocarbon generation potential and thermal maturity of coal and coaly mudstones from the eocene urahoro group in the kushiro coal basin kushiro basin of eastern hokkaido japan the coal is classified as subbituminous or high volatile c bituminous and characterized by high hydrogen content 6 1 0 4 wt 1 dry ash free basis the hydrogen index hi 180 409 mg hydrocarbon g total organic carbon and random mean vitrinite reflectance vrr 0 42 0 56 indicate that the coal and coaly mudstones in the urahoro group are gas and oil prone or oil prone based on the hi and vrr values the effective oil window starts at vitrinite reflectance ranges of 0 55 to 0 80 the vitrinite reflectance of coal samples from the kushiro coal mine is inversely proportional to the hi value although each coal seam has the identical thermal history this result suggests that the vitrinite reflectance of the samples in the kushiro coal mine is suppressed based on the corrected vitrinite reflectance non suppressed vitrinite reflectance the maturity of the coal in the kushiro basin increases towards the north the non suppressed vitrinite reflectance of the samples from the northernmost part of the basin hokuyo area was approximately 0 8 which is within the start of the oil window the maturity of the coal bearing strata in the northern area of the basin could be affected by volcanic activity along the volcanic front in the hokuyo area the urahoro group overlies a sequence of cretaceous eocene marine clastic rocks nemuro group which are about 3000 4000 m in total thickness suggesting that the organic matter in the marine clastic rocks should reach higher maturity vrr 0 8

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

global ocean meridional overturning abstract a decade mean global ocean circulation is estimated using inverse techniques incorporating air sea fluxes of heat and freshwater recent hydrographic sections and direct current measurements this information is used to determine mass heat freshwater and other chemical transports and to constrain boundary currents and dense overflows the 18 boxes defined by these sections are divided into 45 isopycnal neutral density layers diapycnal transfers within the boxes are allowed representing advective fluxes and mixing processes air sea fluxes at the surface produce transfers between outcropping layers the model obtains a global overturning circulation consistent with the various observations revealing two global scale meridional circulation cells an upper cell with sinking in the arctic and subarctic regions and upwelling in the southern ocean and a lower cell with sinking around the antarctic continent and abyssal upwelling mainly below the crests of the major bathymetric ridges

application of acritarch fluorescence in thermal maturity studies the relative fluorescence of acritarchs 400 700 nm range was investigated as an alternative technique of determining the level of thermal maturity of marine paleozoic source rocks in canada the sedimentary strata examined include the blue mountain lindsay collingwood mbr guelph eramosa mbr and marcellus formations from southern ontario yeoman and winnipegosis formations from saskatchewan as well as the manitoba and elk point groups from saskatchewan and alberta respectively the examined strata contain oil prone predominantly marine organic matter type ii and i kerogen with varying proportions of bituminite and alginite as the dominant maceral components acritarchs which occur as persistent maceral inclusions within such organic facies show excellent potential in thermal maturity estimations the fluorescence of acritarchs shows a progressive red shift throughout the initial and main stages of oil generation with a trend parallel to that of alginite however as a result of their lower sensitivity to increasing burial temperature the amax and q values of acritarchs are lower than the corresponding amax and q of gloeocapsomorpha prisca and leiosphaeridia alginite with the difference becoming more pronounced with increasing thermal maturity correlations with optical and geochemical maturity indicators such as reflectance of chitinozoa chr o bitumen br o and vitrinite vr o rock eval tmax and the isomerization ratio of regular steranes s s r indicate that in kerogen type ii organic matrix both amax and q values of acritarchs vary little until the onset of oil generation at this maturity level corresponding to vr o 0 5 and tmax 435 c amax values are commonly 450 nm or less whereas q is below 0 5 within the zone of the initial phase of oil generation the amax shows a steady increase to 480 nm and then a more rapid raise throughout the oil window 520 550 nm these changes in amax are not accompanied by a meaningful increase in q values which in general remain around 0 5 in kerogen type i organic matrix no significant variations in amax and q have been observed up to a maturity level corresponding to vr o 1 and tmax up to 460 c

comparison of two petrographic methods for determining the degree of anomalous vitrinite reflectance abstract three australian permian bituminous coals from well documented geological settings chosen to cover a range of rank and orthohydrous subhydrous and perhydrous vitrinite compositions were used to compare and contrast two petrographic methods for correcting anomalies in vitrinite reflectance vr due to compositional variation one of the methods fluorescence alteration of multiple macerals famm is based on the fluorescence alteration properties of coal macerals and the other on paired measurements of reflectance and fluorescence intensity the methods are only applicable to fresh unoxidised coals or dispersed organic matter dom both methods use a reference normal orthohydrous telovitrinite line on which results from perhydrous or subhydrous samples are projected to obtain the equivalent reflectance of orthohydrous telovitrinite the results of the two methods on the test samples are similar but they differ in detail

organic petrology of source rocks history and state of the art abstract the development of organic source rock petrology depended on the methods applied a procedure derived from coal petrology is the study of polished sections of the untreated rock under incident light this method combined with the fluorescence techniques is best suited to characterize and identify the discrete organic matter macerals and permits the most reliabble maturity measurements on the basis of vitrinite reflectance and of various fluorescence parameters another common method treats the rock with acids and studies strew slides of organic matter concentrates this destroys the natural texture of the rock and often some of the individual macerals as well but on the other hand it allows recognition of extremely fine particles which are not resolvable in polished sections maturity studies based on maceral colour changes as observed in strew slides are rapid and practical although they are rather subjective the relative merits of the various methods are discussed the individual organic constituents as seen in the whole rock and in organic matter concentrates are described and illustrated in two colour plates some classification systems are compared in tabular form finally the history of microscopic observations and measurements with respect to the generation of petroleum like substances in coal is briefly reviewed

direct observations of formation and propagation of subpolar eddies into the subtropical north atlantic abstract subsurface float and moored observations are presented to show for the first time the formation and propagation of anticyclonic submesoscale coherent vortices that transport relatively cold fresh subpolar water to the interior subtropical north atlantic acoustically tracked rafos floats released in the southward flowing western boundary current at the exit of the labrador sea reveal the formation of three of these eddies at the southern tip of the grand banks 42 n 50 w using a recently developed method to detect eddies in float trajectories and estimate their kinematic properties it was found that the eddies had average rotation periods of 5 7 day at radii of 10 25 km with mean rotation speeds of up to 0 3 m s 1 one especially long lived 5 1 months eddy crossed under the gulf stream path and translated southwestward in the subtropical recirculation to at least 35 n where it hit one of the corner rise seamounts velocity temperature and salinity measurements from a nine month deployment of two moorings south of the gulf stream at 38 n 50 w reveal the passage of at least two eddies with similar hydrographic and kinematic properties the core temperature and salinity properties of the eddies imply their formation at intermediate levels of the labrador current south of the tail of the grand banks these observations confirm earlier speculation that eddies form in this region and transport anomalously cold low salinity water directly into the subtropical interior possible formation mechanisms and potential importance of these eddies to interior ventilation and the equatorward spreading of labrador sea water are discussed

coherent mesoscale eddies in the north atlantic subtropical gyre 3 d structure and transport with application to the salinity maximum the mean vertical structure and transport properties of mesoscale eddies are investigated in the north atlantic subtropical gyre by combining historical records of argo temperature salinity profiles and satellite sea level anomaly data in the framework of the eddy tracking technique the study area is characterized by a low eddy kinetic energy and sea surface salinity maximum although eddies have a relatively weak signal at surface amplitudes around 3 7 cm the eddy composites reveal a clear deep signal that penetrates down to at least 1200 m depth the analysis also reveals that the vertical structure of the eddy composites is strongly affected by the background stratification the horizontal patterns of temperature salinity anomalies can be reconstructed by a linear combination of a monopole related to the elevation depression of the isopycnals in the eddy core and a dipole associated with the horizontal advection of the background gradient by the eddy rotation a common feature of all the eddy composites reconstructed is the phase coherence between the eddy temperature salinity and velocity anomalies in the upper 300 m layer resulting in the transient eddy transports of heat and salt as an application a box model of the near surface layer is used to estimate the role of mesoscale eddies in maintaining a quasi steady state distribution of salinity in the north atlantic subtropical salinity maximum the results show that mesoscale eddies are able to provide between 4 and 21 of the salt flux out of the area required to compensate for the local excess of evaporation over precipitation

paleo heat flow evolution of the tabei uplift in tarim basin northwest china abstract the paleo heat flow evolution of the tabei uplift in the tarim basin is investigated based on burial and thermal history reconstruction of 14 wells and using basin modeling numerous geological parameters such as temperature data and missing sediment thickness by erosion were used in the modeling the basin model was calibrated using 460 measured vitrinite reflectance vr o and vitrinite like maceral reflectance vlmr o values to constrain the validity of the maturity model the heat flow history of the tabei uplift tarim basin shows the following characteristics 1 the highest paleo heat flow was predicted to have occurred in the early ordovician as 65 5 mw m 2 and gradually decreased to 55 5 mw m 2 during the late carboniferous 2 a thermal kick was modeled to have occurred in the permian as suggested by an abrupt rise in the heat flow 3 the heat flow gradually decreased since the triassic 4 the present day heat flow was predicted to be as low as 38 mw m 2 this heat flow history honors the geologic and tectonic evolution history of the tabei uplift and is suggested as the best case heat flow model

vertical structure of mesoscale eddies in the eastern south pacific ocean a composite analysis from altimetry and argo profiling floats 1 the mean vertical structure of mesoscale eddies in the peru chile current system is investigated by combining the historical records of argo float profiles and satellite altimetry data a composite average of 420 526 profiles acquired by argo floats that surfaced into cyclonic anticyclonic mesoscale eddies allowed constructing the mean three dimensional eddy structure of the eastern south pacific ocean key differences in their thermohaline vertical structure were revealed the core of cyclonic eddies ces is centered at 150 m depth within the 25 2 26 0 kg m 3 potential density layer corresponding to the thermocline in contrast the core of the anticyclonic eddies aes is located below the thermocline at 400 m depth impacting the 26 0 26 8 kg m 3 density layer this difference was attributed to the mechanisms involved in the eddy formation while intrathermocline ces would be formed by instabilities of the surface equatorward coastal currents the subthermocline aes are likely to be shed by the subsurface poleward peru chile undercurrent in the eddy core maximum temperature and salinity anomalies are of 1 c and 0 1 with positive negative values for aes ces this study also provides new insight into the potential impact of mesoscale eddies for the cross shore transport of heat and salt in the eastern south pacific considering only the fraction of the water column associated with the fluid trapped within the eddies each ce and ae has a typical volume anomaly flux of 0 1 sv and yields to a heat and salt transport anomaly of 1 3 1011 w and 3 8 103 kg s 1 respectively

quantification of tertiary exhumation in the united kingdom southern north sea using sonic velocity data sonic velocities from the upper and middle chalk upper cretaceous the bunter sandstone and the bunter shale both lower triassic were used to independently quantify apparent exhumation height above maximum burial depth in the united kingdom uk southern north sea apparent exhumation is the displacement on the depth axis of a given velocity depth trend from the normal unaffected by exhumation trend apparent exhumation results derived from the upper and middle chalk the bunter sandstone and the bunter shale are statistically similar the consistency of results from carbonate and clastic units suggests that at a formational and regional scale overcompaction i e anomalously high sonic velocity in all three units analyzed reflects previously greater buria depth rather than sedimentological and or diagenetic processes and validates the use of lithologies other than shale in maximum burial depth studies the consistency of results from units of early triassic to late cretaceous age suggests that tertiary exhumation was of sufficiently great magnitude to mask any earlier mesozoic periods of exhumation and that maximum mesozoic cenozoic burial depth in the southern north sea was attained prior to tertiary exhumation the proposed magnitudes of exhumation are generally greater than those previously published for the southern north sea but they are consistent with recent estimates from apatite fission track analysis the amount of exhumation of the rock column is greatest on the recognized inversion axes i e sole pit cleveland where it reaches approximately 2 5 km however there was a regional component of 1 0 1 5 km exhumation during the tertiary that affected structurally uninverted areas and on which the more localized inversion related exhumation was superimposed cretaceous tertiary burial prior to exhumation must have been of greater magnitude and more rapid than suggested by the preserved stratigraphy the effect of this extra burial and subsequent exhumation on sedimentary rock decompaction procedure and thermal maturation modeling is illustrated for the cleethorpes 1 and 44 7 1 wells and must also be incorporated in modeling reservoir diagenesis the regional tertiary tectonic uplift associated with exhumation must have had a thick skinned origin

hydrogen gas of organic origin in shales and metapelites abstract the changes in inorganic and organic gases retained in shales and metapelites with increasing heating temperature are not fully understood the compositional and isotopic changes of residual gases such as h 2 ch 4 and co 2 in marine shales and metapelites during burial diagenesis and metamorphism were investigated in the present study shale rocks and metapelites which experienced paleo temperatures in the range of 100 600 c were collected from the borehole cores in niigata sedimentary basin and outcrops exposed in kochi district japan gases released from shale or metapelite fragments during pulverization in the laboratory were analyzed as the residual gas the major residual gas in shales and metapelites changes from co 2 ch 4 to h 2 in this order with increasing temperature drastic decrease of co 2 derived from decarboxylation of sedimentary organic matter is due to the expulsion of pore fluids with dissolved co 2 the ch 4 concentration in residual gas subsequently increases with organic maturation and reaches the maximum at paleo temperature of ca 250 c the ch 4 concentration decreases during late metagenesis to metamorphism probably due to the formation of h 2 gas and graphite the h 2 starts to increase at paleo temperature of ca 200 c the h 2 gas is the most abundant gas in residual gas of metapelite the 2 value of h 2 in shales and metapelites is quite low to be in the range of ca 850 to 650 the change of major residual gas from ch 4 to h 2 with increasing paleo temperature and the significantly low 2 h values of h 2 suggest that h 2 gas in shales and metapelites is largely derived from liberation of hydrogen in organic matter

pyrolysis studies on the conversion of vitrinite reflectance and the primary productivity of various non marine source rocks in china abstract a wide range of sediments formed in various sedimentary environments including coals carbargillites shale and mudstones collected throughout china have been studied by laboratory pyrolysis the results show that the vitrinite reflectivity ro values of these samples generally increase with an increase of pyrolysis temperature however the degree of increase in vitrinite reflectance is different from sample to sample the corresponding pyrolysing temperatures for the peak generation of liquid hydrocarbons also reveal the apparent fluctuation among the samples these variations are largely controlled by the properties of the source rock and types of organic matter which are closely related to the primary sedimentary environments therefore the sedimentary environment age and the buried history should be considered when ro and hydrocarbon yield of source rock are used to assess the source rock and basin

an altimetry based gravest empirical mode south of africa 1 development and validation 1 hydrographic transects of the antarctic circumpolar current acc south of africa are projected into baroclinic stream function space parameterized by pressure and dynamic height this produces a two dimensional gravest empirical mode gem that captures more than 97 of the total density and temperature variance in the acc domain weekly maps of absolute dynamic topography data derived from satellite altimetry are combined with the gem to obtain a 16 year time series of temperature and salinity fields the time series of thermohaline fields are compared with independent in situ observations the residuals decrease sharply below the thermocline and through the entire water column the mean root mean square rms error is 0 15c 0 02 and 0 02 kg m 3 for temperature salinity and density respectively the positions of acc fronts are followed in time using satellite altimetry data these locations correspond to both the observed and gem based positions the available temperature and salinity information allow one to calculate the baroclinic zonal velocity field between the surface and 2500 dbar this is compared with velocity measurements from repeat hydrographic transects at the goodhope line the net accumulated transports of the acc derived from these different methods are within 1 3 sv of each other similarly gem produced cross sectional velocities at 300 dbar compare closely to the observed data with the rms difference not exceeding 0 03 m s 1 the continuous time series of thermohaline fields described here are further exploited to understand the dynamic nature of the acc fronts in the region and which is given by swart and speich 2010

long term observations of north atlantic current transport at the gateway between western and eastern atlantic in the western north atlantic warm and saline water is brought by the north atlantic current nac from the subtropics into the subpolar gyre four inverted echo sounders with high precision pressure sensors pies were moored between 47 40 n and 52 30 n to study the main pathways of the nac from the western into the eastern basin the array configuration that forms three segments northern central and southern allows partitioning of the nac and some assessment of nac flow paths through the different mid atlantic ridge fracture zones we exploit the correlation between the nac transport measured between 2006 and 2010 and the geostrophic velocity from altimeter data to extend the time series of nac transports to the period from 1992 to 2013 the mean nac transport over the entire 21 years is 27 5 sv consisting of 60 warm water of subtropical origin and 40 subpolar water we did not find a significant trend in the total transport time series but individual segments had opposing trends leading to a more focused nac in the central subsection and decreasing transports in the southern and northern segments the spectral analysis exhibits several significant peaks the two most prominent are around 120 days identified as the time scale of meanders and eddies and at 4 9 years most likely related to the nao transport composites for the years of highest and lowest nao indices showed a significantly higher transport 2 9 sv during strong nao years mainly in the southern segment

a high resolution salinity time series 1993 2012 in the north atlantic from argo and altimeter data the study of salinity changes has been hampered by the lack of temporal and spatial resolution of the observations in order to improve the spatial and temporal distribution of salinity observations we used the gravest empirical mode gem technique to calculate high resolution salinity distributions as a function of dynamic height for the period 1993 2012 this technique combined argo and altimeter data to exploit the relationship between t s profiles and dynamic height in the north atlantic the method was valid in the upper 700 m mainly at and near the pathways of the north atlantic current nac but failed in regions with weak stratification or with ambiguities in the t s relationships coherent multiannual large scale variability was observed with many features present in all regions albeit with weaker amplitudes in the eastern basins some of the interannual features in the northeastern atlantic basins were unrelated to the variability further south and west pointing to an occasional advection of subtropical water in the eastern atlantic origin and advection of salinity anomalies with the nac from the north american basin into the western subpolar north atlantic are correlated with the state of the north atlantic oscillation nao and dampened by the surface freshwater fluxes other mechanisms influencing the salinity pattern are the changing location of the subpolar front also related to the nao the large multiyear variability in the 20 year time series obscured any potential trends caused by global warming only the rockall trough showed a salinity increase of 0 03 per decade

upb dating of calcite concretions from cambrian black shales and the phanerozoic time scale the u pb dating of carbonate offers considerable potential for accurate and direct dating of sedimentary rocks here we show that carbonate concretions from the upper cambrian black shales in southern scandinavia have remarkably high u to pb ratios 238u204pb up to 288 000 permitting precise geochronology a fine crystalline early diagenetic concretion yields an age of 509 8 5 1 ma providing an accurate age for the late cambrian whereas a coarse cone in cone concretion has yielded an age of 478 2 4 9 ma defining the final stage of sediment compaction and indicating a protracted dewatering and diagenetic history these results demonstrate the power of this method for directly calibrating the geological time scale and constraining diagenetic histories

palynomorph optical analyses for thermal maturity assessment of upper ordovician katian hirnantian rocks from southern estonia abstract application of integrated multi proxy optical analytical techniques for the assessment of thermal maturity of organic matter was tested in katian to hirnantian upper ordovician sediments from a subsurface succession in southern estonia the investigated valga 10 drill core section consists of a biostratigraphically well constrained succession deposited in the outer part of a carbonate shelf livonian basin the diverse and well preserved palynological assemblages permitted the analysis of thermally induced modifications of optical properties of small and large acanthomorph acritarchs qualitative methods such as uv fluorescence and acritarch alteration index aai were calibrated against the quantitative palynomorph darkness index pdi the occurrence of vitrinite like organoclasts allowed reflectance measurements in some of the investigated samples the strong fluorescence and pale to yellow colour of acritarchs combined with low pdi and organoclast reflectance values suggest thermally immature kerogen and a limited burial diagenesis in the study area moreover pdi showed a good correlation with uv fluorescence allowing a calibration of these two techniques and proving the reliability of pdi for thermal maturity estimation in sedimentary rocks unsuitable for rock eval pyrolysis and vitrinite reflectance furthermore the applied methodologies permitted the differentiation of reworked from in situ organic matter and highlighted the potential of the former for sequence stratigraphic investigations

stratigraphy and structure of the schoonover sequence northeastern nevada implications for paleozoic plate margin tectonics radiolarian biostratigraphy and detailed geologic mapping have been used to resolve the complex structure and stratigraphy of part of the golconda allochthon in the independence mountains nevada here the schoonover sequence is latest devonian to early permian in age spanning the time interval from the emplacement of the roberts mountains allochthon onto the shelf in the earliest mississippian antler orogeny to the inception of the sonoma orogeny the history of the schoonover basin is tied to that of the adjacent shelf in nevada and provides important insights into the upper paleozoic paleogeographic framework of the continental margin in the schoonover sequence latest devonian famennian chert overlies basaltic and andesitic greenstone and is in turn overlain by early mississippian kinderhookian chert interbedded with tuff and volcaniclastic rocks derived from an island arc the kinderhookian volcaniclastic rocks grade upward with no obvious depositional break into siliciclastic turbidites and pebbly mudstones that contain debris derived primarily from erosion of the antler orogenic belt although in some beds volcanic rock fragments and greenschist grade metasedimentary clasts are also common the age of underlying kinderhookian and interbedded and overlying osagian to meramecian chert sequences indicates that the siliciclastic turbidites are synchronous with the early deposits of the autochthonous foredeep basin of the antler orogenic belt the dual or composite source terranes represented by the schoonover siliciclastic rocks place the basin between an arc and the antler orogen on the edge of the shelf meramecian age basalt flows in the schoonover are coeval with subsidence and basaltic volcanism in autochthonous shelf sequences in northern nevada suggesting that a rifting event may have occasioned the end of antler age compression in nevada the onset of limestone turbidite deposition in the schoonover corresponds to the reestablishment of carbonate shelf conditions on the continental margin in latest mississippian earliest pennsylvanian time the late devonian earliest mississippian part of the schoonover depositional history has not yet been documented elsewhere in the golconda allochthon but late mississippian to permian rocks in the schoonover sequence are analogous to those of the havallah sequence suggesting deposition in the same basin thrust faults in the schoonover repeat the late devonian to permian section detaching the basinal sequence from its depositional basement thrust faults extend along strike for at least 10 km but thrust plates are the stratigraphic relations documented in the schoonover sequence are compatible with a back arc thrusting model for the formation of both the roberts mountains and golconda allochthons but they are more difficult to reconcile with models that interpret the allochthons as accretionary prisms developed in front of farther traveled arcs that collided with a passive margin in a broader context the stratigraphy of upper paleozoic allochthonous rocks in nevada records short lived episodes of crustal shortening along the continental margin separated by longer episodes of extensional and or transcurrent tectonics this data suggest that the western united states was a southwest pacific style active margin at least as far back as the devonian

hydrothermally influenced cementation of sandstone an example from deeply buried cambrian sandstones from bornholm denmark abstract cambrian sandstones on bornholm denmark are tightly cemented by quartz cementation occurred after deep burial as evidenced by a very strong compaction partly mediated by intensive grain fracturing the quartz cement has a complex cathodoluminescence sem cl zonation which is related to variable substitution of al in the quartz lattice based on the substitution pattern and sem cl zonation three phases of quartz growth can be identified phase 1 cement has a low sem cl level and its volume corresponds approximately to the estimated volume of press solved detrital quartz it is related to the late compaction phase 2 cement is the volumetrically most important it has an intricate sem cl zonation and associated al substitution it is referred to hydrothermal activity related to the permo carboniferous magmatic and tectonic event the cementation gradually reduced the influence of hydrothermal flow and late phase 3 cement has a low intensity and more simple sem cl pattern the almost fully cemented sandstone was fractured and the fractures were filled by hydrothermal chlorite sulphides and quartz these minerals are also found sporadically as cement in the sandstones

geochemical modeling of sedimentary rocks in the central hokkaido japan episodic deformation and subsequent confined basin formation along the eastern eurasian margin since the cretaceous abstract late cretaceous to paleogene tectonic episodes around the eastern eurasian margin are described utilizing one dimensional 1d basin modeling technique on the basis of organic maturation vitrinite reflectance and t max parameter values of the rock eval pyrolysis fine grained marine sediment of the yezo supergroup in central hokkaido is one of the most extensive cretaceous constituents along the plate margin to evaluate organic maturation within the yezo supergroup a surface section hakkin zawa and a deep borehole miti yubari were selected from which quite different maturation trends were obtained notably low and constant maturation was suggested throughout the thick hakkin zawa section and it was confirmed on the basis of various biomarker analyses it requires anomalously rapid burial probably related to thrust stacking or large scale slumping followed by prompt tilting exhumation event in sharp contrast late cretaceous strata in the miti yubari do not indicate coeval tectonic disturbances in a short period a wider view of the ancient convergent margin suggests that deformation of the forearc propagated westward during the cretaceous high maturation levels in the uppermost thrust sheet around the miti yubari are optimized in 1d geochemical modeling on the assumption that a thick missing paleogene unit has been eroded out as a result of thrust forming contraction scheme emerged during the neogene a similar cenozoic burial pattern is adopted for the once tilted and exhumed hakkin zawa section in order to match the present maturation levels although such an active subsidence of a forearc is generally interpreted as an effect of the subduction erosion heavy mineral composition of the shallow marine to fluvial paleogene implies uplift and exhumation of ultramafic rocks to the east trench side thus the confined basin formation in central hokkaido is to be understood in a different tectonic framework that may reflect transcurrent motions on the plate margin

an experimental study of organic inorganic interactions during vitrinite maturation abstract vitrinite reflectance is a parameter widely used to determine the extent of thermal maturation in sedimentary basins laboratory heating experiments were conducted to examine the role of aqueous fluid and sediment composition temperature and time on the development of vitrinite reflectance at elevated temperatures and pressures samples of organic lean middle valley sediment containing dispersed vitrinite and wyodak coal composed almost entirely of vitrinite were heated in the presence of compositionally variable aqueous fluids at 225 to 375 c and 350 bars inorganic fluid composition was monitored as a function of time and vitrinite reflectance was measured at the termination of each experiment the rate of vitrinite maturation was influenced by inorganic fluid and vitrinite composition in addition to time and temperature during the experiments in particular the rate at which vitrinite reflectance increased for a given temperature correlated positively with in situ h activity this observation suggests that acid catalyzed ionic reaction mechanisms and or catalytically active transition metals and sulfur species play an important role in organic transformations responsible for increased vitrinite reflectance the activity of other inorganic ionic species such as mg ca na k and so 4 and the redox state of the fluid did not influence the rate of vitrinite maturation during these experiments results of this study demonstrate that the geochemical environment surrounding vitrinite influences the rate of maturation the presence of water may facilitate reaction pathways that are not readily available in dry systems vitrinite maturation profiles that deviate from what are considered to be normal trends may reflect subsurface variations in the composition of pore fluids or the presence or absence of an aqueous phase in contact with vitrinite particles accordingly kinetic models that consider organic reactions responsible for increased vitrinite reflectance in terms of time and temperature alone may not accurately account for geochemical processes occurring in natural systems

structural and hydrogeologic evolution of the putumayo basin and adjacent fold thrust belt colombia this multidisciplinary study evaluates the structural and hydrogeologic evolution of cretaceous age reservoirs in the putumayo basin colombia we focused on the eastern cordillera fold thrust belt along the southern garzon massif many important hydrocarbon accumulations occurred regionally along the proximal foreland basin and frontal fold thrust belt defining the eastern margin of the northern andes to understand why recent putumayo basin and adjacent thrust belt exploration has resulted in a wide range of oil quality and limited economic discoveries we reconstructed the structural evolution timing of oil migration and timing of groundwater infiltration by 1 assessing regional trends in formation water oil and reservoir properties 2 quantifying the timing of hydrocarbon generation and migration relative to trap formation using a two dimensional 2 d and three dimensional seismic data to define and constrain a restorable balanced cross section from the upper magdalena valley to the putumayo foreland and b coupled one dimensional thermal basin modeling 3 evaluating the potential roles of mesozoic extensional faulting and paleogene shortening in the generation and preservation of structural traps and 4 assessing groundwater influx from the modern foothills into the reservoir using a 2 d numerical groundwater flow model we suggest that four way closure is limited in the study area where most foreland verging structures create three way fault closures that do not effectively trap light hydrocarbons in addition east dipping structures and a relatively large reservoir outcrop area provide water infiltration pathways groundwater modeling suggests reservoirs were water washed by 2 200 million pore volumes since andean uplift finally average reservoir temperatures are 80 c 176 f which further facilitated biodegradation

strong eddy compensation for the gulf stream heat transport using a high resolution ocean model forced with high resolution atmospheric fields a 5 year mean heat budget of the upper ocean in the gulf stream gs region is analyzed the heat brought to the region with the mean flows along the gs path is 2 3 times larger than the heat loss to the atmosphere with the difference being balanced by a strong cooling effect due to lateral eddy heat fluxes however over a broad area off the grand banks the eddies warm the uppermost ocean layers partly compensating for the loss of heat to the atmosphere the upward eddy heat flux which brings heat from the deeper ocean to the upper layers is 30 80 of the surface heat loss

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

a census of north brazil current rings observed from topex poseidon altimetry 1992 1998 six years of topex poseidon altimeter data are used to investigate the formation of rings and eddies shed by the north brazil current upper layer thickness maps were used to identify 34 of these features formed in the north brazil current retroflection region an average of more than 5 rings and eddies per year the ensemble of ring trajectories closely parallels the 500 m isobath and one out of six rings penetrate into the caribbean sea through the southern lesser antilles the rest of the rings and eddies follow a northern trajectory past barbados once they reach 58w their estimated mean translation speed is 14 km day and their mean length scale is approximately 100 km our results suggest that the formation rate of nbc rings and eddies is nearly twice that previously thought and that they may account for more than 1 3 of the interhemispheric transport within the atlantic meridional overturning cell

vitrinite and vitrinite like solid bitumen reflectance in thermal maturity studies correlations from diagenesis to incipient metamorphism in different geodynamic settings abstract vitrinite reflectance vr is a useful and reliable parameter to monitor the level of organic matter maturation from the immature stage to graphite additionally vr is a useful and essential tool in modelling the temperature maturation time path huminite vitrinite bearing sedimentary and meta sedimentary rocks can be used to reconstruct the thermal history of basins or orogenic terranes throughout their geological history the usefulness of vr evidently depends on the presence of huminite vitrinite phytoclasts however pre upper silurian rocks and many organic rich marine rocks e g sapropelic sediments lack of huminite vitrinite particles furthermore vitrinite is sparse in carbonate sediments however the presence of bitumen in rocks lacking type iii kerogen provides a valuable aid via its reflectance vitrinite like solid bitumen reflectance vlbr and or solid bitumen reflectance br to fulfil the above described tasks that vr enables this study presents basically a relationship between br vlbr and vr for various types of geodynamic settings and over the largest possible range of maturation levels so that vlbr may be used as a substitute for vr whereas the effort to correlate vr with br is not novel it is the first time that the vr br correlation is re judged discriminating bitumen from vlb moreover for the first time the correlation is established for various geodynamic settings the investigated geological contexts are 1 sedimentary basins e g the saar ruhr ohio west virginia and petrosani basins 2 metasedimentary terranes occurring as inverted basins in orogenic belts e g from the subalpine molasse helvetic austroalpine and danubian nappe systems and having suffered from very low to low grade metamorphism from anchizone to greenschist facies 3 metasedimentary terranes e g slates and schists from the franciscan and alpine belts that were subducted at anchizone to blueschist facies conditions and 4 metasedimentary rocks affected by contact metamorphism together the frequent geological settings are referred and most of the earth geothermal conditions and heat fluxes considered despite temperature pressure and heating time also heat flow gradient dependences cannot be ignored

mesoscale eddies in the northwestern pacific ocean three dimensional eddy structures and heat salt transports the region encompassing the kuroshio extension ke in the northwestern pacific ocean 25 n 45 n and 130 e 180 e is one of the most eddy energetic regions of the global ocean the three dimensional structures and transports of mesoscale eddies in this region are comprehensively investigated by combined use of satellite data and argo profiles with the allocation of argo profiles inside detected eddies the spatial variations of structures of eddy temperature and salinity anomalies are analyzed the results show that eddies predominantly have subsurface near surface intensified temperature and salinity anomalies south north of the ke jet which is related to different background stratifications between these regions a new method based on eddy trajectories and the inferred three dimensional eddy structures is proposed to estimate heat and salt transports by eddy movements in a lagrangian framework spatial distributions of eddy transports are presented over the vicinity of the ke for the first time the magnitude of eddy induced meridional heat freshwater volume transport is on the order of 0 01 pw 103 m3 s the eddy heat transport divergence results in an oceanic heat loss south and heat gain north of the ke thereby reinforcing and counteracting the oceanic heat loss from air sea fluxes south and north of the ke jet respectively it also suggests a poleward heat transport across the ke jet due to eddy propagation

reflected light microscopy of chitinozoan fragments abstract certain optical properties of some silurian ordovician chitinozoans have been measured and their morphology described using polished block mounted samples and polished thin sections the chitinozoans were found to be optically isotropic and many fine details of their morphology were observed using reflected light microscopy it has also proved possible to recognize chitinozoan fragments in sections made from kerogen concentrates and whole rock samples from early palaeozoic sediments using reflected light microscopy reflectance studies indicate their potential use as maturity indicators

eddy properties in the western mediterranean sea from satellite altimetry and a numerical simulation three different eddy detection and tracking methods are applied to the outputs of a high resolution simulation in the western mediterranean sea in order to extract mesoscale eddy characteristics the results are compared with the same eddy statistics derived from satellite altimetry maps over the same period eddy radii are around 30 km in altimetry maps whereas in the model they are around 20 km this is probably due to the inability of altimetry maps to resolve the smaller mesoscale in the region about 30 eddies are detected per day in the basin with a very heterogeneous spatial distribution and relatively short lifespans median life around 13 days unlike other areas of the open ocean they do not have a preferred direction of propagation but appear to be advected by mean currents the number of detected eddies seems to present an annual cycle when separated according to their lifespan with the numerical simulation we show that anticyclones extend deeper in the water column and have a more conic shape than cyclones

eddy activity in the four major upwelling systems from satellite altimetry 1992 2007 eddy activity in the four major eastern boundary upwelling systems ebus is investigated using 15 years of satellite altimetry data based on the analysis of more than 4000 long lived eddy trajectories in every ebus we show that mesoscale structures are mainly generated along the continental coasts and south of the main archipelagos and propagate westward with velocities increasing toward the equator these mesoscale eddies having radii of 70 160 km are then frequently observed along the coastal transition zones and frontal regions and some large oceanic areas are preferentially populated by cyclonic or anticyclonic eddies temporal variations of the number of newly formed eddies and the associated eddy activity index defined as the mean eddy energy density are finally examined at seasonal and interannual scales the strongest seasonal interannual respectively variations are observed in the california benguela upwelling systems the proposed indices also exhibit contrasted long term trends in each ebus which suggests that eddy activity might be sensitive to a warming climate

main eddy vertical structures observed in the four major eastern boundary upwelling systems in the four major eastern boundary upwelling systems ebus mesoscale eddies are known to modulate the biological productivity and transport near coastal seawater properties toward the offshore ocean however little is known about their main characteristics and vertical structure this study combines 10 years of satellite altimetry data and argo float profiles of temperature and salinity and our main goals are i to describe the main surface characteristics of long lived eddies formed in each ebus and their evolution and ii to depict the main vertical structure of the eddy types that coexist in these regions a clustering analysis of the argo profiles surfacing within the long lived eddies of each ebus allows us to determine the proportion of surface and subsurface intensified eddies in each region and to describe their vertical structure in terms of temperature salinity and dynamic height anomalies in the peru chile upwelling system 55 of the sampled anticyclonic eddies aes have subsurface intensified maximum temperature and salinity anomalies below the seasonal pycnocline whereas 88 of the cyclonic eddies ces are surface intensified in the california upwelling system only 30 of the aes are subsurface intensified and all of the ces show maximum anomalies above the pycnocline in the canary upwelling system 40 of the aes and 60 of the ces are subsurface intensified with maximum anomalies extending down to 800 m depth finally the benguela upwelling system tends to generate 40 50 of weak surface intensified eddies and 50 60 of much stronger subsurface intensified eddies with a clear geographical distribution the mechanisms involved in the observed eddy vertical shapes are discussed

optical properties of organic matter in relation to thermal gradients and structural deformation the general response of macerals to the coalification process the effectiveness of organic geochemical and petrological parameters as estimators of coalification and the applicability of different microscopical parameters in the assessment of rank are reviewed the central role of vitrinite reflectance as the most widely used estimator of coalification from brown coals to the low grade metamorphic zone is established on the basis of its relatively uniform variation with rank specificity ease and rapidity of measurement and cheapness factors influencing the optical properties ofvitrinites are considered temperature has the dominant influence in modifying optical properties with rank but time static pressure and stress can all have significant influences upon the course of optical properties depending upon particular geological conditions static pressure has a retarding effect on the coalification process but it is also responsible for creating increasing anisotropy within the condensing aromatic structures as rank rises hydrostatic pressures and pore pressures can contribute to the overpressuring of sediments thus affecting their thermal conductivities and consequently the rate of coalification stress is responsible for the development of biaxicity in the reflectance indicatrix fast and high levels of heating from igneous bodies cause textural effects on vitrinites as a result of carbonization that are quite different from those of coalification recognizing these different influences upon the optical properties of vitrinites examples are given of the use and application of vitrinite reflectance in the preparation of rank maps in the burial histories of basins in the timing of coalification in relation to orogenesis and igneous activity and in the zones of anchimetamorphism and low grade metamorphism consideration is also given to the problem of provincialism in correlations between chemical and physical parameters and to the future development of optical studies in organic petrology and their relation to organic geochemical investigations

a simpler kinetic model of vitrinite reflectance we have developed simple ro as a simpler but conceptually compatible alternative to existing kinetic models for vitrinite reflectance such as vitrimat and easy ro where calculations are done using the isothermal segment approach simple ro is much faster where the constant heating rate segment approach is used simple ro and easy ro are of similar speed simple ro is based on a single activation energy in each time step rather than on a range this activation energy changes as a function of ro thus simulating the maturity dependent change in activation energy distribution observed in nature simple ro can be calibrated to any desired distribution of activation energies or can be calibrated against measured ro data independent of any other kinetic model

upper limits for vitrinite and bituminite reflectance as coalification parameters abstract reflectance versus depth diagrams for vitrinite from carboniferous beds and for bituminite from the late permian kupferschiefer in northern germany led to the conclusion that there may exist upper limits for the applicability of reflectance as a maturity parameter at 6 r r and 8 r max for vitrinite or 4 r r and 5 r max for bituminite the vitrinite threshold values may mark the end of the diagenesis anchimetamorphism field and the boundary between meta anthracite and semi graphite

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

later palaeozoic radiolaria in thrust belts of nevada the use of later palaeozoic radiolaria as age indicators in n nevada has made possible stratigraphic comparisons between a small part of the golconda allochthon the schoonover sequence the structurally underlying roberts mountains allochthon and sequences which formed in a foreland in a foreland basin as the roberts mountains allochthon was emplaced at the north american continent margin miller et al 1984 emplacement of the cambrian to devonian deeper water roberts mountains allochthon rocks occurred in kinderhook osage time johnson pendergast 1981 and is usually viewed as a consequence of latest devonian to early mississippian antler orogenesis the late devonian to mid permian golconda allochthon rocks were probably emplaced in the early mesozoic radiolaria are essential to the elucidation of the older golconda succession hitherto unsuspected similarities between events recorded by these older golconda rocks and those recorded in the antler foreland basin seem at variance with the proposal that the golconda allochthon is a relatively far travelled accretionary prism which became part of north america in the early mesozoic speed sleep 1982 it might rather seem that the schoonover basin was the exterior oceanward analogue of the antler foreland basin it originated during the first late devonian volcaniclastic supply but shared with the foreland basin a mississippian siliciclastic source in the roberts mountains allochthon and suffered the same intra pennsylvanian movements that are recorded in successions the schoonover basin existed therefore at the continent margin adjacent to the 9antler volcanic arc9 postualated by several authours and to the eroding roberts mountains allochthon

carbon isotope composition of lower palaeozoic kerogen effects of maturation abstract the carbon isotope composition of type i kerogen from a marine organic rich black shale deposit of late cambrian age the alum shale formation of southern scandinavia varies from 28 to 30 pdb the thermal maturity is rated by hi oi index t max pi and vitrinite reflectance values and published conodont alteration data the results range from immature conditions with regard to oil generation in central sweden to overmature and submetamorphic conditions in southern sweden denmark and norway in the immature areas the shale is found to be extremely hydrogen rich and oil prone hydrocarbon potential up to 85 kg per ton rock the observed 13 variations are not correlated with maturity it is therefore concluded that thermal maturation processes have no influence on the isotopic composition of a purely marine kerogen the observed range in lower palaeozoic 13 kerogen values 27 to 31 is in accordance with published results from other sedimentary basins

stable carbon isotopes of amorphous kerogens from phanerozoic sedimentary rocks amorphous kerogens from phanerozoic sedimentary rocks may be divided into two groups on the basis of their 13c values h amorphous kerogens have isotopic values in the range of 24 to 20 per mil and l amorphous kerogens have isotopic values in the range of 35 to 26 per mil the occurrence of amorphous kerogens in the intermediate isotopic range from one rock unit in the data set suggests a weak continuum may exist between these two groups phytoplankton and to a lesser extent zooplankton and bacteria are considered to be the precursors for both kerogen types a plausible explanation for this dichotomy may be found in the source of co2 utilized by phytoplankton which is considered to be controlled by environmental factors h amorphous kerogens are expected to occur in silled basins that are overlain by expansive well circulated deep 500 m water where the prevailing source of carbon in the photic zone is atmospheric derived co2 conversely l amorphous kerogens are expected to occur in restricted basins that are overlain by stratified shallow 200 m water where the prevailing source of carbon in the photic zone may be organic derived co2

irradiation of organic matter by uranium decay in the alum shale sweden the alum shale of sweden contains black shales with anomalously high uranium concentrations in excess of 100 ppm syngenetic or early diagenetic origin of this uranium indicates that organic matter within these shales has been irradiated by decaying uranium for approximately 500 ma radiation induced polymerization of alkanes through a free radical cross linking mechanism appears to be responsible for major alterations within the irradiated organic matter specific radiation induced alterations include generation of condensate like oils at reduced yields from hydrous pyrolysis experiments decrease in atomic h c ratios of kerogens decrease in bitumen organic carbon ratios and a relative increase in low molecular weight triaromatic steroid hydrocarbons conversely stable carbon isotopes of kerogens reflectance of vitrinite like macerais oil generation kinetics and isomerization of 20r to 20s c29 steranes were not affected by radiation the radiation dosage needed to cause the alterations observed in the alum shale has been estimated to be in excess of 105 mrads with respect to organic carbon this value is used to estimate the potential for radiation damage to thermally immature organic matter in black shales through the geological rock record high potential for radiation damage is not likely in cenozoic and mesozoic black shales but becomes more likely in lower paleozoic and precambrian black shales

pathways of cross frontal exchange in the north atlantic current the north atlantic current nac forms part of the boundary between the subtropical and subpolar gyres in the north atlantic ocean the current has topographically controlled stationary meanders that appear to grow and decay a region east of the current in the newfoundland basin contains water of mixed subpolar subtropical properties suggesting that there is exchange across the nac this study considers data from isopycnal rafos floats launched in the nac region from 1993 to 1995 we use the rafos data to define the frontal zone as a pressure range where the jet is most likely to be found this definition requires a latitudinal dependence as the nac shoals to the north floats shallower and deeper than this range are defined to be on the subpolar and subtropical side respectively these definitions are used to estimate mixing that occurs between the current and its surroundings and to estimate the relative quantity of exchange of water parcels between the two gyres only small quantities of mass exchange from one gyre to the other are found but there is a distinct asymmetry leading to a mean flux from the subpolar to subtropical sides we also find that floats spend significant time in the frontal region and are frequently exchanged between fast and slow moving waters particularly at the meander extrema diffusion while in the jet leads to eddy cross frontal exchange which is important for the exchange of properties across the nac

preserved stable isotopic signature of subaerial diagenesis in the mescal limestone central arizona implications for the timing of a terrestrial plant cover discussion and reply discussion

signature of mesoscale eddies in satellite sea surface salinity data a persistent signature of coherent mesoscale eddies in sea surface salinity sss is revealed by analyzing the relationship between satellite sss and sea surface height ssh variability in an eddy following reference frame our analysis focuses on mid ocean eddies in two representative regions the southern indian ocean and the north atlantic subtropical gyre the resulting composite averages reveal a clear signature of mesoscale eddies in satellite sss with typical sss anomalies of 0 03 0 05 psu the spatial structure of eddy induced sss perturbations can be characterized as a superposition of a dipole structure arising from horizontal advection of the background sss gradient by eddy velocity field and a monopole structure related to the eddy core the observed relationships between sss and ssh anomalies are used to provide a regional assessment of the role of mesoscale eddies in the ocean freshwater transport in the north atlantic subtropical gyre this article is protected by copyright all rights reserved

from shale oil to biogenic shale gas retracing organic inorganic interactions in the alum shale furongian lower ordovician in southern sweden methane rich gas occurs in the total organic carbon rich alum shale furongian to lower ordovician in southern sweden the lower part of the thermally immature alum shale was impregnated by bitumen locally generated by heating from magmatic intrusions from the carboniferous to the permian organic geochemical data indicate that the migrated bitumen is slightly degraded in the upper alum shale where methane is the main hydrocarbon in thermovaporization experiments centimeter size calcite crystals occur that contain fluid inclusions filled with oil gas or water the alum shale is thus considered a mixed shale oil biogenic shale gas play the presented working hypothesis to explain the biogenic methane occurrence considers that water soluble bitumen components of the alum shale were converted to methane a hydrogeochemical modeling approach allows the quantitative retracing of inorganic reactions triggered by oil degradation the modeling results reproduce the present day gas and mineralogical composition the conceptual model applied to explain the methane occurrence in the alum shale in southern sweden resembles the formation of biogenic methane in the antrim shale michigan basin united states in both models melting water after the pleistocene glaciation and modern meteoric water may have diluted the contents of total dissolved solids tds in basinal brines such pore waters with low tds contents create a subsurface aqueous environment favorable for microbes that have the potential to form biogenic methane today biogenic methane production rates with shale as the substrate using different hydrocarbon degrading microbial enrichment cultures in incubation experiments range from 10 to 620 nmol per gram and per day

correlation of very low grade data to calibrate a thermal maturity model in a nappe tectonic setting a case study from the alps abstract vitrinite and bituminite reflectance data xrd studies on clay minerals radiometric data and geochemical data have been used to investigate metamorphism of very low and low grade sediments from the lower austroalpine and south penninic nappes in the oberhalbstein valley central alps numerical maturity modelling methods are calibrated with petrological structural and new geochronological data to reconstruct temperature histories even in nappe tectonic settings the combination of low grade data and maturity modelling shows that the duration of peak temperature metamorphism plays an important role in the alteration of organic matter vitrinite reflectance vr often does not correlate with other low grade parameters but in the oberhalbstein equilibrium between the different parameters is evident because heating near the peak conditions for more than 20 ma took place it is proposed to use the comparison to evaluate equilibrium conditions for the temperature parameters in general in addition from petrological work and vr modelling the pressure conditions are estimated the results yield an eroded overburden of 6 1 km and a temperature gradient of 30 2 c km 1 at the base of the nappe stack pressure conditions of 4 1 kbar are determined and therefore no evidences for a high pressure event the main heating is dated between 90 and 70 5 ma and is attributed to nappe stacking in the upper crust

thermal maturity of a fold thrust belt based on vitrinite reflectance analysis in the western foothills complex western taiwan abstract burial depth cumulative displacement and peak temperature of frictional heat of a fault system are estimated by thermal analysis in the fold thrust belt of the western foothills complex western taiwan based on the vitrinite reflectance technique the regional thermal structure across the complex reveals that the rocks were exposed to maximum temperatures ranging from 100 c to 180 c which corresponds to a burial depth of 3 7 6 7 km a large thermal difference of 90 c were observed at the shuilikeng fault which make the eastern boundary of the fold thrust belt where it is in contact with metamorphic rock of hsuehshan range the large thermal difference corresponds to cumulative displacements on the shuilikeng fault estimated to be in the range of 5 2 6 9 km however thermal differences in across the shuangtung and chelungpu faults cannot be determined apparently due to small vertical offsets the large displacement observed across the shuilikeng fault is absent at the other faults which are interpreted to be younger faults within the piggyback thrust system localized high temperatures adjacent to fault zones were observed in core samples penetrating the chelungpu fault three major fracture zones were observed at core lengths of 225 m 330 m and 405 m and the two lower zones which comprise dark gray narrow shear zones a value of vitrinite reflectance of 1 8 higher than the background value of 0 8 is limited at a narrow shear zone of 1 cm thickness at the fracture zone at 330 m the estimated peak temperature in the range of 550 680 c in the shear zone is far higher than the background temperature of 130 c and it is interpreted as due to frictional heating during seismic faulting

temperature flux carried by individual eddies across 47 n in the atlantic ocean surface geostrophic velocity fields derived from satellite altimetry between january 1993 and april 2014 are used to detect and investigate eddies in the north atlantic between 40 55 n and 60 10 w focus is on a zonal section along 47 n roughly at the boundary between the subpolar and the subtropical gyres sea surface temperature data are used to quantify the temperature anomalies associated with eddies and the respective surface temperature fluxes related to these eddies identified eddy pathways across 47 n are related to the mean background velocity from full depth ship observations carried out on 11 cruises between 2003 and 2014 the analysis is repeated in two model simulations with 1 4 and 1 12 horizontal resolution respectively for the period 2002 2013 the analysis reveals almost 37000 altimeter derived eddies with a lifetime longer than one week in the area the highest number of eddies is found along the pathway of the north atlantic current roughly following the 4000 m isobath and on the grand banks of newfoundland time series of temperature fluxes by eddies crossing 47 n reveal that single isolated eddies with large sst signatures contribute 25 to the surface temperature flux relating the observed eddies to the observed top to bottom velocity distribution at 47 n points to the existence of eddy pathways across 47 the highest temperature fluxes are linked to the fastest and most pronounced current branches in the western newfoundland basin while there are fewer eddies in both model simulations the key findings are consistent between the observations and the two model simulations this article is protected by copyright all rights reserved

multiple cooling episodes in the central tarim northwest china revealed by apatite fission track analysis and vitrinite reflectance data apatite fission track and vitrinite reflectance are integrated for the first time to study the cooling history in the central tarim northwest china the paleo temperature profiles from vitrinite reflectance data of the z1 and z11 wells showed a linear relationship with depth suggesting an approximately 24 8 c km paleo geothermal gradient and 2700 3900 m of erosion during the early mesozoic the measured apatite fission track ages from well z2 in the central tarim range from 39 to 159 ma and effectively record the meso cenozoic cooling events that occurred in central tarim moreover two cooling events at 190 140 ma in the early jurassic early cretaceous and 80 45 ma in the late cretaceous paleocene revealed by measured aft data and thermal modeling results are related to the collisions of the qiangtang lhasa terranes and the greater india plate with the southern margin of the eurasian plate respectively this study provides new insights into the tectonic evolution of the tarim basin and more broadly central asia and for hydrocarbon generation and exploration in the central tarim

stirring in the global surface ocean 1 global variations of stirring in the surface ocean are quantified using finite time lyapunov exponents ftles calculated from currents derived from satellite altimetry it is shown that the stirring is highly non uniform and the probability distribution functions pdfs of the ftles are broad asymmetric and have long high stretch tails the characteristics of the pdfs vary with mesoscale activity and integration time there are larger values and broader pdfs in regions of high strain rates and eddy kinetic energy eke e g western boundary currents and the antarctic circumpolar current and for shorter integration times the pdfs have a near universal relationship with the mean strain of a region and are reasonably well fit by weibull distributions the above variations in the stirring may help our understanding of the distribution and spatial heterogeneities of biogeochemical tracers and raise the possibility of developing a parameterization of the stirring based on the easily calculated eke

deep water formation the subpolar gyre and the meridional overturning circulation in the subpolar north atlantic on interannual to decadal times scales model simulations suggest a strong relationship between anomalies in the deep water formation rate the strength of the subpolar gyre and the meridional overturning circulation in the north atlantic whether this is valid can only be confirmed by continuous long observational time series several measurement components are already in place but crucial arrays to obtain time series of the meridional volume and heat transport in the subpolar north atlantic are still missing here we summarize the recent developments of the deep water formation rates and the subpolar gyre transports we discuss how existing observational components in the subpolar north atlantic could be supplemented to provide long term monitoring of the meridional heat and volume transport through a combined analysis of observations and model results the temporal and spatial scales that had to be covered with instruments are discussed together with the key regions with the highest variability in the velocity and temperature fields

timing and mode of emplacement of the roberts mountains allochthon antler orogeny this antler model involves incipient subduction of continental crust and miogeoclinal strata beneath an accretionary wedge composed primarily of oceanic sedimentary rocks and lesser outer shelf strata under thrusting and sediment obduction three phases of associated tectonism are 1 first emplacement phase in which only oceanic crust is subducted evidenced primarily by foreland epeirogeny 2 second emplacement phase in which incipient subduction of continental crust occurs and a flysch trough is formed 3 post emplacement phase of isostatic uplift of continental margin and allochthon accompanied by molasse sedimentation the first two phases associated with compressive movements of the antler orogeny of nevada occurred between mid frasnian and mid osagean time this interval equals about 23 m y based on c a sandberg9s estimates of the duration of conodont zones overlap of the surface trace of the roberts mountains thrust by the kinderhookian webb formation preceded final emplacement of the allochthon ordovician devonian and kinderhookian units in the allochthon as mapped in the carlin pinyon range area by smith and ketner overlie the oldest antler flysch kinderhookian age and are interpreted to have been encased within the antler clastic wedge during osagean time

mesoscale eddies off peru in altimeter records identification algorithms and eddy spatio temporal patterns relatively little is known about coherent vortices in the eastern south pacific along the peruvian coast even with regard to basic facts about their frequency of occurrence longevity and structure this study addresses these issues with nearly 15 years of relatively high resolution satellite altimetry measurements we first compare two distinct automated methods for eddy identification the objective validation protocol shows that the rarely used geometrical or winding angle method based on the curvature of the streamline functions is more accurate than the commonly used okubo weiss algorithm which defines a vortex as a simple connected region with values of okubo weiss parameter weaker than a given threshold we then investigate vortices off peru using more than 20 000 mesoscale eddies identified by the winding angle method coherent eddies characterized by a high ratio of vorticity to deformation rate are typically formed along the coast and propagate westward at 3 6 cm s 1 the vortices have a mean radius of 80 km increasing northward and are most frequently observed off of chimbote 9s and south of san juan 15s the mean eddy lifetime is about 1 month but if eddies survive at least 2 months the probability for surviving an additional week or month is constant at 90 or 67 anticyclonic eddies tend to propagate northwestward whereas cyclonic vortices migrate southwestward in general cyclones and anticyclones are similar except for eddies surviving at least 6 months in this case after a similar 3 4 months of radius and amplitude growth amplitudes or sizes decay particularly rapidly for anticyclonic or cyclonic eddies in terms of intensity cyclonic eddies show a rapid decay during the first 3 months before arriving at a quasi constant value whereas anticyclones exhibit steady decline finally eddy temporal variations were examined at seasonal and interannual scales in the coastal region favorable to the formation of energetic mesoscale structures on seasonal scales eddy activity is maximal in fall and minimum in spring at interannual scales the eddy activity index was maximal during the strong el nino of 1997 1998 but another strong maximum of eddy activity also occurred late in 2004 these temporal variations are probably associated with the intensification of the upwelling thermal front and with the passage of coastal trapped waves which generate baroclinic instabilities further investigation of the mechanisms involved on the eddy genesis is needed

reflectance of vitrinite like macerals as a thermal maturity index for cambrian ordovician alum shale southern scandinavia the middle cambrian to lower ordovician alum shale in southern scandinavia contains kerogen macerals resembling vitrinite the age of this rock unit excludes terrestrially derived vitrinite as an origin for these macerals nevertheless the vitrinite like macerals respond to heating in a way similar to that of suppressed vitrinite in younger shales this similarity is demonstrated both for the natural system where alum shale maturity ranges from immature to low grade metamorphic conditions and for hydrous pyrolysis experiments where an immature sample of alum shale was isothermally heated at temperatures ranging from 280 to 360 degrees c for 72 hr reflectance values from the naturally matured alum shale show an increase in standard deviations i e anisotropy with i creasing maturity and a negative relationship with atomic h c ratios of the total kerogen these relationships are similar to those observed in post ordovician vitrinites comparisons with other vitrinites subjected to hydrous pyrolysis indicate the vitrinite like macerals in the alum shale follow the suppressed vitrinite pathway rather than the coal vitrinite pathway the occurrence of vitrinite like macerals in the alum shale indicates that traditional vitrinite reflectance measurements are useful in evaluating thermal maturity of pre silurian rocks

observed characteristics and vertical structure of mesoscale eddies in the southwest tropical pacific in the southwest pacific ocean waters transit from the subtropical gyre before being redistributed equatorward and poleward while the mean pathways are known the contribution to the mixing and transport of the water from mesoscale eddies has not been comprehensively investigated in this research satellite altimetry data combined with an eddy detection and tracking algorithm is used to investigate the distribution and surface characteristics of mesoscale eddies in this region of complex bathymetry 10 s 30 s 140 e 190 e detected eddies are then colocalized with in situ data from argo floats to determine their vertical structure and the effect of eddies on the water masses the numerous islands affect the eddy behavior as most eddies are formed in the lee of islands propagate westward and decay when encountering shallow bathymetry eddies are sparse and short lived in the tropical area north of fiji impacting only the top 200 meters of water they do not appear to be able to trap and transport waters in this region in the coral sea a region of lateral shear between currents transporting waters of different origins eddies are more numerous and energetic they affect the water properties down to at least 500 m depth and anticyclonic eddies trap water to 200 m contributing to the upper thermocline waters mixing and transport south of new caledonia mesoscale eddies are ubiquitous with typical lifetimes longer than 5 months they affect the temperature salinity and velocities down to 1 000 m depth and weakly contribute to the mixing of lower thermocline waters

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

thermal maturity of carboniferous strata ouachita mountains the ouachita mountains a relatively untested potential hydrocarbon province contain a thick paleozoic section of apparently favorable source beds reservoir beds and trap configurations to estimate the thermal maturity of these strata vitrinite reflectance was measured on 89 samples collected mostly from carboniferous rocks from throughout the ouachita outcrop area thermal maturity contours generally parallel structural grain in the western two thirds of the ouachitas reflectance values in oil range from 3 0 in the core area in oklahoma and from about 1 0 to 3 0 in analogous positions in arkansas older strata on upthrown sides of thrust faults are more thermally mature than younger strata on downthrown sides in the eastern one third of the outcrop belt thermal maturities are significantly higher 2 0 5 0 ro and thermal maturity contours cut obliquely across structural grain strata on either side of thrust faults display identical levels of maturity in the western two thirds of the ouachitas sedimentary and tectonic burial have been the major influences of thermal maturation although a mesozoic thermal overprint has increased levels of maturity in arkansas throughout this area strata are within the oil and wet gas windows the anomalous levels and patterns of thermal maturity in the eastern third of the ouachitas are probably the result of a thermal overprint related to mesozoic rifting and intrusive activity in the mississippi embayment this thermal overprint has elevated the maturity of strata in most of this area above the level of hydrocarbon preservation although maturities within the dry gas window are retained locally

vertical structure and transport on a transect across the north atlantic current near 42 n time series and mean a new method is presented for combining historical hydrography with the acoustic travel time measurements from an inverted echo sounder ies to obtain time series of full water column profiles of temperature t and specific volume anomaly hydrography is used to demonstrate that profiles constructed from the ies measurement account for more than 90 of the t and variance through the main thermocline range horizontal gradients between neighboring pairs of instruments when combined with measurements from bottom pressure sensors and deep current meters provide accurate estimates of absolute geostrophic velocity profiles a section of iess and current meters across the north atlantic current nac along world ocean circulation experiment line acm6 near 42 5 n is analyzed using these methods and the eulerian mean temperature and absolute velocity sections are calculated the mean transport for the combined nac and northward flow within the inshore portion of the mann eddy is 146 13 106 m3 s 1 the temporal standard deviation of the northward transport is 41 106 m3 s 1 arising not only from changes in the transport of the nac but also from lateral shifts of the currents and eddies captured by the fixed span of moorings assumption of a level of no motion at the bottom and at 2000 dbar underestimates the true absolute transport by 33 or 60 respectively historical measurements indicate that 50 60 106 m3 s 1 circulates within the mann eddy adjacent to the north atlantic current thus 86 96 106 m3 s 1 appears to be throughput at the acm6 line because the throughput observed on the acm6 line considerably exceeds the combined historical estimates of northward and eastward outflow from the newfoundland basin of 30 106 m3 s 1 these measurements suggest a substantial 50 106 m3 s 1 recirculation or southward flow within the newfoundland basin in addition to the historical recirculation within the mann eddy

palynology and palynofacies analysis of a silurian llandovery wenlock marine succession from the precordillera of western argentina palaeobiogeographical and palaeoenvironmental significance abstract a comprehensive survey of the marine and terrestrial palynomorphs from the la chilca formation exposed in the central precordillera of san juan argentina is presented twenty four samples from the quebrada ancha section were analysed marine phytoplankton predominated in the entire stratigraphic unit while the contribution of terrestrial palynomorphs was much less acritarchs and chlorophytes represent a highly diversified assemblage including stratigraphically relevant taxa such as domasia trispinosa tylotopalla caelamenicutis tylotopalla digitifera crassiangulina variacornuta stellinium rabians and percultisphaera cf stiphrospinata terrestrial palynomorphs are exclusively represented by six cryptospore species namely gneudnaspora divellomedia pseudodyadospora laevigata rugosphaera cerebra tetrahedraletes medinensis cf imperfectotriletes vavdovae and velatitetras retimembrana comparisons with coeval phytoplankton assemblages from gondwana and other palaeoplates such as laurentia baltica and avalonia show strong similarities suggesting a cosmopolitan distribution pattern during the llandovery and wenlock the first palynofacies analysis for the early silurian of argentina was performed depositional environments based on palynofacies match with those previously suggested based on sedimentological data two main palynofacies associations are recognised association b occurs in the lower part of the la chilca formation and is mostly composed of amorphous organic matter aom representative of low energy inner shelf environments association a is recognised in the upper part of the formation where sandstone beds become more frequent and is characterised by a greater amount of possible palynomorph remains ppr indicating a proximal platform to shoreface environment three excursions of total organic carbon toc were identified in the section probably as a result of sea level rise episodes that produced anoxic conditions and preservation of organic matter

western boundary currents regulated by interaction between ocean eddies and the atmosphere current climate models systematically underestimate the strength of oceanic fronts associated with strong western boundary currents such as the kuroshio and gulf stream extensions and have difficulty simulating their positions at the mid latitude ocean s western boundaries1 even with an enhanced grid resolution to resolve ocean mesoscale eddies energetic circulations with horizontal scales of about a hundred kilometres that strongly interact with the fronts and currents the bias problem can still persist2 to improve climate models we need a better understanding of the dynamics governing these oceanic frontal regimes yet prevailing theories about the western boundary fronts are based on ocean internal dynamics without taking into consideration the intense air sea feedbacks in these oceanic frontal regions here by focusing on the kuroshio extension jet east of japan as the direct continuation of the kuroshio we show that feedback between ocean mesoscale eddies and the atmosphere ome a is fundamental to the dynamics and control of these energetic currents suppressing ome a feedback in eddy resolving coupled climate model simulations results in a 20 40 per cent weakening in the kuroshio extension jet this is because ome a feedback dominates eddy potential energy destruction which dissipates more than 70 per cent of the eddy potential energy extracted from the kuroshio extension jet the absence of ome a feedback inevitably leads to a reduction in eddy potential energy production in order to balance the energy budget which results in a weakened mean current the finding has important implications for improving climate models representation of major oceanic fronts which are essential components in the simulation and prediction of extratropical storms and other extreme events3 4 5 6 as well as in the projection of the effect on these events of climate change