atmospheric fronts along the east coast of taiwan studied by ers synthetic aperture radar images the existence of quasi stationary alongshore atmospheric fronts typically located 30 70 km off the east coast of taiwan is demonstrated by analyzing synthetic aperture radar sar images of the sea surface acquired by the european remote sensing satellites ers 1 and ers 2 for the data interpretation cloud images from the japanese geostationary meteorological satellite gms 4 and the american terra satellite rain rate maps from ground based weather radars sea surface wind data from the scatterometer on board the quick scatterometer quikscat satellite and meteorological data from weather maps and radiosonde ascents have also been used it is shown that these atmospheric fronts are generated by the collisions of the two airflows from opposing directions one is associated with a weak easterly synoptic scale wind blowing against the high coastal mountain range at the east coast of taiwan and the other with a local offshore wind at the convergence zone where both airflows collide air is forced to move upward which often gives rise to the formation of coast parallel cloud bands there are two hypotheses about the origin of the offshore wind the first one is that it is a thermally driven land breeze katabatic wind and the second one is that it is wind resulting from recirculated airflow from the synoptic scale onshore wind air blocked by the mountain range at low froude numbers is recirculated and flows at low levels back offshore arguments in favor of and against the two hypotheses are presented it is argued that both the recirculation of airflow and land breeze katabatic wind contribute to the formation of the offshore atmospheric front but that land breeze katabatic wind is probably the main cause

alteration of crystalline basement rocks by hydrocarbon bearing fluids moinian of ross shire scotland abstract moinian proterozoic gneisses in easter ross shire scotland exhibit pronounced alteration where they have been subjected to the flow of hydrocarbon bearing fluids from an adjacent devonian sedimentary basin comparison of the petrography of altered and unaltered gneiss indicates that element redistribution accompanied the alteration process the alteration involved creation of secondary porosity by dissolution of primary minerals in the gneiss chloritization of biotite and precipitation of authigenic orthoclase cross cutting veinlets include bitumen authigenic quartz orthoclase albite monazite and titanium oxides attesting to redistribution of all the major components of the gneiss evidence for bitumen being coeval with albite quartz and an association of high porosity with bitumen indicate that hydrocarbon bearing fluids were present during the alteration process bitumen also penetrated beyond the visible alteration zone and accreted around radioelement bearing accessory minerals organic geochemical data indicate that there is a local source for the bitumen in the devonian sequence bitumen veining also occurs within the devonian sequence fluid inclusion data from quartz associated with bitumen in the gneiss and the devonian indicate minimum trapping temperatures of 120 140 and 100 120 c respectively the alteration was probably a result of a fluid flow episode relating to fault movement during basin subsidence

petrography and origin of deposits at the bentheim bitumen mine north western germany the fracture bound deposit at the sieringhoek bentheim bitumen mine in nw germany has yielded a substantial quantity of bitumen ore emplacement of the bitumen into the fracture system occurred under high pressure causing brecciation and impregnation of the host gildehaus sandstone subsequently the bitumen was brecciated and cemented by calcite and calcite entrained sand bitumen injection followed fracturing into a hydro carbon reservoir at depth generated from a jurassic cretaceous source rock diagenesis of the host rock was largely completed by the time of bitumen injection reflecting the long time gap during which source rock maturation occurred impurities in the bitumen include large quantities of rock fragments abraded during injection and crystals of metal oxides and sulphides

interaction of low level flow with the western ghat mountains and offshore convection in the summer monsoon abstract seven year averaged values of percent frequency of occurrence of highly reflective cloud for the months june july and august indicate that offshore convection is a major component of the cloudiness of the southwest monsoon principal areas of convection occur off of the western coats of india burma thailand and the philippines this study concentrates on the area upstream of the western ghats mountains of india analysis of a special boundary layer mission flown during the wmo icsu summer monsoon experiment leads us to believe that partial deceleration of the monsoon flow by upstream blocking effects of the mountains initiates and maintains a vertical and horizontal motion field that could support the observed convection data obtained on this mission allow a large scale momentum budget computation for the subcloud layer which shows pressure deceleration to be significant the budget dominated by advection predicts an increase of average wind speed which is observed the pressure decelera

the application of electron microscopy and microanalysis in conjunction with organic petrology to further the understanding of organic mineral association examples from mount isa and mcarthur basins australia organic petrology supported by electron microscopical and micro analytical techniques was applied to organic matter in proterozoic sediments to better understand hydrothermal processes responsible for ore grade mineralisation it was shown that organic maturation was not only closely linked to the geological history of the sediments but also highlighted heat transfer by convection as differentiated from conduction solely through sediment burial and step wise subsidence water rock ratios effect organic maturation in hydrothermal systems and erratic reflectance profiles are indicators of convective heat transfer identification and characterisation of organic materials in terms of source rock and migrated hydrocarbons was shown to be a powerful tool in reconstructing the thermal history of sediments identifying hydrothermal episodes fluid pathways and heat source in the northern australian proterozoic basins higher reflectance of organic matter towards the central parts of the mount isa basin and some of the most northerly parts point to proximity to higher heat flow at times in contrast to relatively low temperatures prevailing in the western parts of the basin next to the murphy inlier a close correlation shown between peak organic reflectance values and super sequence boundaries farther highlighted the valuable information to be gained from organic petrology by allowing the separation of processes responsible for metal dissolution and transportation from those inducing precipitation c 2001 elsevier science b v all rights reserved

winter monsoon convection in the vicinity of north borneo part i structure and time variation of the clouds and precipitation abstract radar and satellite observations in the vicinity of northern borneo obtained during the international winter monsoon experiment wmonex showed that the convection in that region underwent an extremely regular diurnal cycle over the sea to the north of borneo the general level of convective activity was increased during monsoon surges and during the passages of westward propagating near equatorial disturbances convective activity was decreased during monsoon lulls the diurnal cycle was well defined regardless of whether the general level of convective activity was enhanced or suppressed by synoptic scale events the cycle of convection over the sea was especially well documented it was typically initiated at about midnight when an offshore low level wind began where this wind met the monsoonal northeasterly flow usually just off the coast convective cells formed after midnight the convection continued to develop and by 0800 lst it had evolved into an organized mesoscale system with a

a theory for strong long lived squall lines abstract we study herein the mechanics of long lived line oriented precipitating cumulus convection squall lines using two and three dimensional numerical models of moist convection these models used in juxtaposition enable us to address the important theoretical issue of whether a squall line is a system of special long lived cells or whether it is a long lived system of ordinary short lived cells our review of the observational literature indicates that the latter is the most consistent paradigm for the vast majority of cases but on occasion a squall line may be composed of essentially steady supercell thunderstorms the numerical experiments presented herein show that either type of squall line may develop from an initial line like disturbance depending on the magnitude and orientation of the environmental shear with respect to the line with shallow shear oriented perpendicular to the line a long lived line evolves containing individually short lived cells our analysis of this type o

hydrocarbon compositions of bitumens associated with igneous intrusions and hydrothermal deposits in britain abstract the possible modes of formation and thermal history of various palaeozoic and precambrian bitumens associated with hydrothermal deposits and igneous intrusions have been evaluated by molecular organic geochemistry the aliphatic hydrocarbon compositions of extracts of such bitumens from a number of localities have been determined by gc and gc ms procedures the stereochemical configurations and low abundance of their steranes hopanes and degraded hopanes resemble those characteristic of various mature weathered and biodegraded crude oils comparisons of the distributions of tricyclic terpanes hopanes demethylated hopanes 8 14 secohopanes and steranes reveals a close correspondence between all the bitumens from the welsh borderlands correlations suggestive of a common source rock the occurrence and abundance of 8 14 secohopanes in the bitumens is consistent with their generation as thermal degradation products of hopanes a similar mode of formation is proposed for the other unidentified secohopane in a bitumen from the midland valley of scotland overall the hydrocarbon compositions of the bitumens are compatible with their ultimate biological origins and subsequent thermal experience

three dimensional shuffling of horses in a strike slip duplex an example from the lambertville sill new jersey abstract detailed analysis of a dextral strike slip duplex within the relatively isotropic rocks of the lambertville sill new jersey indicates that horses have experienced vertical horizontal and oblique movements resulting from extrusional shuffling within a restraining bend this is the first documentation of the three dimensional movement of horses within a strike slip duplex deformation within the duplex shows a complex system of early synthetic fractures and reverse faults followed by antithetic fractures which dissect previously continuous slab shaped horses into diamond shaped lenses most faults are oblique slip antithetic fault movements and clockwise rigid rotation of horses dominate the south half of the duplex and synthetic movements and counterclockwise rotations dominate the north half slickenline plunges on curved horse bounding fault surfaces within the duplex range from nearly horizontal to 40 resulting in both lateral movements middle to normal movements tails on a single horse curved slickensides commonly have opposite senses of movement on either side of individual horses indicating relative emergence or submergence such a geometry could also result from a group of horses moving in the same oblique direction but at different rates these complex extrusional type movements were observed in both cross sectional and plan views the net result of the movements is a contraction or flattening of the duplex normal to the bounding faults the horses shifted to accommodate this flattening as overall displacement was transferred between the bounding faults along curved internal faults

upstream effects of mesoscale mountains abstract the alpine experiment alpex has revealed that low level air is typically diverted around the alps without reaching the mountaintop in pursuit of an understanding of the physical basis of this phenomenon and of its generality we have explored the characteristics of orographic blocking of a rotating continuously stratified quid as revealed in a simple model problem retaining full nonlinear and transient effects hydrostatic dynamics is assumed and the obstacle is taken to be an infinitely long ridge with height h x the key questions treated are the strength of the upstream deceleration of cross mountain flow and the length scale over which the decelerated region extends by means of scale analysis the controlling parameters are found to be the rossby number ro u fl and the froude number fr nhm u where u is the speed of the oncoming flow f is the coriolis parameter l the mountain half width n the brunt vaisala frequency and hm is the maximum mountain height the scale analysis also

discrimination of bitumen sources in precambrian and lower palaeozoic rocks southern u k by gas chromatography mass spectrometry abstract two distinct sources for bitumen shows in lower palaeozoic and precambrian rocks in the welsh borderland can be successfully discriminated using gas chromatography mass spectrometry bitumens are widespread in the region in rocks from late precambrian longmyndian to silurian age previous geological studies have suggested that some bitumens originated from pre devonian source rocks while others migrated downwards laterally from carboniferous rocks this possibility has now been confirmed by organic geochemical studies which have also clarified the origin of some bitumens whose affinities had not been clear those bitumens concluded to have migrated from the carboniferous have also been correlated with bitumens within carboniferous rocks further east they are characterized by relatively high levels of hopanes c 27 c 29 to c 35 max c 29 or c 30 the bitumens with an assumed pre devonian source contain n alkylcyclohexanes range c 15 to c 32 max c 18 or c 19 which are absent in the other bitumens and they can be matched with a longmyndian black shale although detailed correlations are limited by the very high maturity of the samples the pre devonian bitumens also show several affinities with the distinctive ordovician oils

the transition of the hurricane frederic boundary layer wind field from the open gulf of mexico to landfall abstract numerous aircraft ship buoy and land nation data were composited with respect to the center of hurricane frederic for two time periods a 24 h period corresponding to the storm s position in the open gulf of mexico on 12 september 1979 and an 8 h period corresponding to the landfall of frederic near 0400 gmt on 13 september comparison of wind analyses for the two periods indicated a rotation of maximum inflow angles from the southeast to northeast quadrants and a strong frictional decrease of wind speed over land them and other features of the landfall analysis were compared with a model landfall study by moss and jones 1978 the landfall composite wind field was compared with the fujita damage vector analysis to determine the damage time interval and mean wind speed range damage vector directions were found to be well correlated with the surface streamlines with the most severe damage being associated with frederic s northern eyewall ten meter level wind speed data over water vo and

a preliminary morphology of precipitation systems in tropical northern australia a preliminary morphology of convective systems observed in the vicinity of darwin australia is presented several types of tropical convection during monsoonal and break season flow are identified using specific examples and compared with a range of systems observed worldwide in the general context of the bulk richardson number a significant spectrum of convective activity ranging from low shear and low convective available potential energy cape to high shear and moderate to high cape typical of mid latitude severe storms is identified significant differences between monsoonal flow and break season systems are apparent the formation of convective lines perpendicular to the low level shear and the apparent balance between advancing shallow cold pools and the shear are ubiquitous features convective scale downdraughts and mesoscale descent appear to be responsible for redistribution of 700 mb momentum to the planetary boundary layer pel the motion of the break season squall lines appears to result from an equilibrium between the cold pool and the undisturbed environmental pel flow deviations from this balance are hypothesized to result in the observed propagating and non propagating or slow moving modes examples of these modes are given showing the classical continuous development of new cells in a balanced state along the leading edge of long lived squalls and in the propagating case the discontinuous development of new cells on the cold pool ahead of the squall

application of major and trace elements as well as boron isotopes for tracing hydrochemical processes the case of trifilia coastal karst aquifer greece the trifilia karst aquifer presents a complex hydrochemical character due to the intricate geochemical processes that take place in the area their discernment was achieved by using the chemical analyses of major trace elements and boron isotopes major ion composition indicates mixing between seawater and freshwater is occurring five hydrochemical zones corresponding to five respective groundwater types were distinguished in which the chemical composition of groundwater is influenced mainly due to the different salinization grade of the aquifer the relatively increased temperature of the aquifer indicates the presence of hydrothermal waters boron isotopes and trace elements indicate that the intruding seawater has been hydrothermally altered as it is shown by the 11b depleted signature and the increased concentrations of li and sr trace elements analyses showed that the groundwater is enriched in various metallic elements which derive from the solid hydrocarbons bitumens contained in the carbonate sediments of the tripolis zone the concentration of these trace elements depends on the redox environment thus in reductive conditions as mn co and nh4 concentrations are high in oxidized conditions the v se mo tl and u concentration increases while ni is not redox sensitive and present high concentration in both environments

sandstone hosted thorium bitumen mineralization in the northwest irish basin low grade sandstone hosted thorium mineralization is recorded in the carboniferous northwest irish basin in the republic of ireland and northern ireland the thorium is concentrated within bitumen nodules which are replacive within the sandstones a source of thorium was available in a caledonian granite in the basin watershed and the bitumen was a product of hydrocarbons generated within the basin the thorium occurs as thorite inclusions in the bitumen and the development of the nodules was enhanced by the polymerization of fluid hydrocarbons by irradiation from the thorium thorium mobility may have been enhanced by the formation of organometallic complexes mineralization probably therefore occurred during hydrocarbon migration dated as late carboniferous to permian

diagnosed characteristics of precipitation systems over taiwan during the may june 1987 tamex abstract characteristics of mei yu precipitating cloud systems over taiwan during the may june 1987 taiwan area mesoscale experiment tamex have been studied using sounding surface precipitation and radar data vertical motion has been computed over the island at 6 h intervals from 13 may to 15 june using a modification of the kinematic method that takes into account the mountainous lower boundary within a four station sounding polygon two primary characteristics of the precipitation have been found first the major rainfall event were linked to the passage of midlatitude disturbances and typically consisted of both deep convective and stratiform components deep convection was primarily prefrontal or frontal while the stratiform precipitation was postfrontal presumably in association with overrunning and orographic lifting second there was a pronounced diurnal variability in the rainfall vertical motion heating q1 and moistening q2 profiles have been used to define the character of the pr

spatial patterns of convection in south florida abstract although they are a fairly consistent feature the sea breeze and lake breeze convergence lines and the associated convection over south florida during the summer may vary considerably from one day to the next daily radar maps indicate a few basic recurring patterns analyses of radiosonde data show significant differences corresponding to the different patterns in the local thermodynamic parameters most notably the mixing ratio changes in the synoptic scale wind field correspond closely to changes in the observed radar patterns and the local thermodynamic conditions explanation of the formation and development of the different patterns of convection is given in terms of the complex interaction between the regional synoptic peninsular and local scale circulations

sulphur isotopic investigation of lower carboniferous vein deposits of the british isles similar characteristics and age data suggest that the pb zn vein deposits hosted by lower palaeozoic and vendian strata of the british isles form a genetically related group coeval with the lower carboniferous carbonatehosted base metal deposits of ireland sulphur isotopic data demonstrate that there were separate sulphide and sulphate sulphur sources for the vein minerals 34s values from minerals in individual vein systems are consistent but there is a large variation between deposits revealing distinctive local sulphur sources the data suggests that sulphide sulphur total range of values of 34sh2s of 6 5 to 18 62 was derived from the underlying strata while the sulphate baryte sulphur source 34sbaryte mainly in the range 12 to 24 was groundwater or surface water that mixed with rising hydrothermal fluids in the upper reaches of the veins

statistical location and timing of the convective lines off the mountainous coast of southeastern taiwan from long term radar observations in this study observations from the c band doppler radar on green island which is located off the southeastern coast of taiwan during 1998 2004 were analyzed to investigate the statistical characteristics of the convective lines occurring off the mountainous coast of southeastern taiwan with emphasis on their formative location and timing a total of 211 cases of the lines were identified during the study period it is shown that the lines were clearly a year round phenomenon and five cases occurred per month on average statistical analyses for all identified cases reveal that the formative area of the lines was extended substantially from nearshore regions to at least 100 km offshore with the region of the most frequent formation primarily confined to an elongated zone located 30 km off the coast along coast variations of line formation were also evident and were shown to be closely related to the nearshore terrain features the lines tended to form more frequently during the nighttime hours than the daytime hours with a formative peak between 2000 and 2200 lst minimum formation was found near noon between 1200 and 1400 lst however considerable cases still could be found during the late morning and late afternoon hours more than 70 of the lines 150 cases had a duration of less than 4 h and the mean duration for all lines was calculated to be 3 5 h in addition this study also documented statistical differences in the formative and flow characteristics between the nearshore and offshore lines which are distinguished by offshore distances of formative location that are less or greater than 40 km respectively of particular note the analyses presented strongly suggest that the physical mechanisms contributing to the initiation of the nearshore and offshore lines are fundamentally different

hydrocarbon compositions of bitumens from mineralized devonian lavas and carboniferous sedimentary rocks central scotland abstract solid bitumens occur in mineralized veins in the lower devonian ochil volcanic formation in the midland valley of scotland bitumens are also widespread in the carboniferous of the midland valley gas chromatography g c mass spectrometry m s studies undertaken on bitumens from the devonian rocks and on devonian and carboniferous mudrocks show that the bitumens contain biomarkers and that carboniferous rocks are the more likely source for the bitumens hydrocarbons may have migrated into the devonian rocks along the ochil fault zone from a downthrown carboniferous basin to the south of the fault the organic geochemistry of bitumen samples from the carboniferous rocks reflects varying degrees of biodegradation and heating by igneous intrusions

migration of biogenic hydrocarbons into granites a review of hydrocarbons in british plutons abstract the occurrence of hydrocarbons bitumens senso lato in granite plutons and other basement rocks is not per se evidence of an abiogenic origin for the hydrocarbons on the contrary plutons are thermal foci and often highly fractured and therefore are hosts to the migration of fluids from outside the plutons including water and biogenic hydrocarbons hydrocarbons are associated with several british granites in all cases they can be attributed to biogenic sedimentary source rocks the occurrences are particularly related to hydrothermal mineralized veins in granites including the cornish hercynian granites the mountsorrel granodiorite and the weardale granite

metal organic relationships from the irish carboniferous abstract a number of metal organic relationships have been observed in the carboniferous of ireland they include metal enrichments within black shales bitumen nodules bituminous solution seams woody material vein bitumens and reservoir bitumens and the association of hydrocarbon gases and bitumens with base metal deposits the source for the metals may have been in the strata on which the carboniferous rocks were deposited or in their carboniferous erosion products both syngenetic and epigenetic mineralisation have been observed with organic material associated with both types of mineralisation the solid bitumens are residues of migrated fluid hydrocarbon which may have been produced by 330 ma late visean

on the dynamics of hawaiian cloud bands island forcing abstract this study focuses on basic island scale forcing mechanisms for the formation and evolution of a band cloud typically present upwind of the island of hawaii by means of numerical experiments and verification of our results against observations and laboratory experiments reported in the literature we show that the band cloud is a complex three dimensional phenomenon which is inseparable from the airflow around the island in particular we demonstrate that the event needs to be analyzed in terms of the basic fluid dynamics of strongly stratified flow past a three dimensional obstacle the band cloud is found to arise primarily from the dynamic interaction of the trade winds with the island the upwind surface flow forms a separation line with an associated stagnation point a low level convergence zone forms along this line resulting in an updraft line if the updrafts are strong enough a band cloud forms formation and characteristics of such a system are mostly controlled by the environmenta

the control of basin evolution on patterns of sedimentation and diagenesis an example from the mississippian great orme north wales the mississippian north wales platform is located on the margins of the east irish sea basin and has been little studied over the last 30 years the exposed visean limestones provide new insights into the deposition porosity evolution distribution of dolomitization and pb zn and cu mineralization on the north wales carbonate platform this is of relevance to the characterization of fault related dolomite hydrocarbon reservoirs and age equivalent mississippi valley type mineral deposits in particular the study demonstrates the intimate relationship between sedimentation basin scale tectonism and post depositional fluid flux depositional cyclicity is marked with metre scale upward shallowing cycles in which pervasive marine and meteoric calcite cements occlude matrix porosity and syndepositional fractures consequently subsequent burial diagenetic replacive dolomitization is matrix selective and cements are primarily restricted to fractures seven phases of dolomite are defined based on texture and cathodoluminescence petrography with phases d1 d3 as the most volumetrically significant dolomite phases d0 d2 are matrix replacive cross cutting stratigraphy and locally fingering along beds for several metres dolomite phases d3 d7 are hosted by faults and fractures and also line vugs evidence of telogenesis is recorded where burial diagenetic products are post dated by calcite cements precipitated from meteoric fluids dolomitization probably occurred during the mississippian and continued into the pennsylvanian pb zn mineralization is also interpreted to have occurred during the pennsylvanian associated with variscan tectonism overall the north wales platform displays a more complex paragenesis than age equivalent platforms in the pennine basin owing to multiple phases of burial and exhumation the study demonstrates the importance of linking burial history to detailed field and petrographical data to understand and predict the spatial and temporal controls on diagenetic processes and products within syn and post rift sequences

the influences of inversion height on precipitation and airflow over the island of hawaii abstract both the daily rainfall on the windward side of the island of hawaii and the early morning 0200 hst hawaiian standard time trade wind inversion height at hilo varied substantially during the hawaiian rainband project harp in general the inversion was higher during the passage of a cold front to the north or during the approach of tropical disturbances from the east to the south the daily rainfall on the windward side is highly correlated with the 0200 hst inversion height at hilo with a maximum correlation greater than 0 7 in the hilo area the daily daytime 1100 1900 hst rainfall on the windward slopes nocturnal 1900 0300 rst showers an the windward lowland and coastal precipitation in the predawn and early morning hours 0300 1100 hst are also highly correlated with the inversion height with a maximum correlation greater than 0 7 0 7 and 0 5 respectively for the low high inversion days the median daily rainfall on the windward side is about one half more than twice of t

evidence of hydrocarbon and metalliferous fluid migration in the palaeoproterozoic earaheedy basin of western australia dolomitized limestones of the earaheedy basin contain solid bitumen and metal sulphides sulpharsenides and arsenides within a network of fractures which acted as pathways for migrating fluids the solid bitumen formed from residual oil that was thermally altered within those fractures immobilization of oil was postdated by precipitation of fracture filling calcite and later replacive dolomite and quartz cements as well as of magnesian chlorite solid bitumen has high concentrations of fe zn pb ni and fecu bearing sulphides sulpharsenides and arsenides in minute inclusions that are randomly distributed throughout its groundmass galena and pyrite also fill cracks in the bitumen whereas pyrite arsenopyrite galena gersdorffite enargite and chalcopyrite fill contraction vugs small crystals of cassiterite are associated with cavity filling magnesian chlorite multiple phases of base metal precipitation are apparent the first indicated by the inclusions probably formed during mixing of hydrocarbon and metal rich fluids later phases resulted from the filling of bitumen contraction structures that formed during and after thermal alteration and degassing processes and which imply the migration of metal rich fluids after oil immobilization the association of metal rich minerals and fracture filling bitumen in this non ore setting is a guide to the possible existence of ore grade mineralization elsewhere in the basin

review and update of the applications of organic petrology part 2 geological and multidisciplinary applications abstract the present paper is focused on organic petrology applied to unconventional and multidisciplinary investigations and is the second part of a two part review that describes the geological applications and uses of this branch of earth sciences therefore this paper reviews the use of organic petrology in investigations of i ore genesis when organic matter occurs associated with mineralization ii the behavior of organic matter in coal fires self heating and self combustion iii environmental and anthropogenic impacts associated with the management and industrial utilization of coal iv archeology and the nature and geographical provenance of objects of organic nature such as jet amber other artifacts and coal from archeological sites and v forensic science connected with criminal behavior or disasters this second part of the review outlines the most recent research and applications of organic petrology in those fields

the chemical composition of specular hematite from tilkerode harz germany implications for the genesis of hydrothermal hematite and comparison with the quadrilatero ferrifero of minas gerais brazil the black shale hosted selenide vein type deposit at tilkerode eastern harz germany has specular hematite enclosed in clausthalite pbse the specular hematite has ti and v in amounts of up to 1 wt tio2 and 3 wt v2o5 and subordinate but important contents of mo 22 372 ppm and b up to 68 ppm the tilkerode hematite serves as a reference for hydrothermal hematite formed at relatively low temperatures 150 c the composition of the tilkerode hematite is compared with that of two generations of specular hematite from itabirite hosted iron ore deposits in the quadrilatero ferrifero of minas gerais brazil the first generation of specular hematite represents an early tectonic hematitisation of dolomitic itabirite at aguas claras and occurs as fine grained crystals reconnaissance data indicate that the aguas claras hematite is poorer in ti and v relative to the tilkerode hematite but has 5 10 ppm b and 7 11 ppm li the second generation of specular hematite defines the pervasive tectonic foliation of the gongo soco iron ore this hematite has ti contents of up to 2 wt tio2 and subordinate amounts of v 62 367 ppm its b and li concentrations are mostly below 2 ppm b and 1 ppm li the presence of ti and b in the tilkerode hematite can be explained by highly saline b bearing fluids that were capable of mobilising otherwise immobile ti the mo signature of the tilkerode hematite suggests that mo was derived from the host black shale in minas gerais b and li were incorporated into the early tectonic hematite from saline fluids at relatively low temperatures aguas claras and then released during metamorphic hematite growth at higher temperatures as suggested by the foliation defining hematite without b li signature gongo soco

occurrences and origin of reservoir solid bitumen in sinian dengying formation dolomites of the sichuan basin sw china abstract reservoir solid bitumen is pervasive throughout the sinian dengying formation dolomites of the sichuan basin and neighboring areas yet its origin remains controversial optical and scanning electron microscope sem studies of the dengying formation were carried out to elucidate the nature and origin of the solid bitumen solid bitumen in dissolution pores intercrystal pores and stylolites appears to have formed in association with regional hydrocarbon charging processes reservoir solid bitumen displays a variety of morphologies each of which appears to reflect different precursor hydrocarbons massive crust like solid bitumen was probably derived from solid precursors whereas finger like solid bitumen likely evolved from liquid precursors sheet like and thin skinned globular solid bitumen appeared to have precipitated from wet gas precursors analyzed solid bitumen is characterized by high random reflectance average 3 4 and bireflectance values 4 2 6 9 exhibits strong optical anisotropy and displays different coke structures including granular mosaic domain and fibrous the coke textures which appear to reflect the nature of bitumen precursors formed by physical coalescence of mesophase spheres and parallel arrangement of laminated aromatic sheets in association with a rapid heating event the inferred thermal episode which is evidenced by the presence of hydrothermal minerals including saddle dolomite quartz authigenic illite and barite may have been associated with the late permian eruption of the emeishan traps thus widespread solid bitumen in the dengying formation reflects the effects of hydrothermal alteration rather than the impact of normal burial related thermal maturation further the close association of sold bitumen and authigenic kaolinite indicates that natural deasphalting plays a role in the formation of reservoir solid bitumen

solid bitumens an assessment of their characteristics genesis and role in geological processes familiar since antiquity and subject in contemporary times to various characterization schemes the exact nature of solid bitumen is not yet fully known bitumens have random polymer like molecular structures are mobile as highly viscous fluids or were once fluids but have since turned into solids solid bitumens consist mainly of large moieties of polyclyclic aromatic hydrocarbons occasionally with finely admixed fine grained cryptocrystalline graphite solid bitumens are distinguished from kerogen which is the syngenetic and generally finely dispersed particulate organic matter in sedimentary rock that virtually does not migrate following its deposition occurrences of solid bitumens are relevant to petroleum exploration as well as the search for and evaluation of a variety of metallic mineral deposits genesis of bitumen is in many cases linked to the thermal and hydrothermal history of organic matter in sedimentary rock apparently bitumen or more specifically organic acids generated along with bitumen during diagenesis may alter porosity of reservoir rocks or otherwise prepare the ground for ore deposition bitumen is also relatively sensitive to alteration processes some of which such as oxidative weathering water leaching biodegradation contact metamorphism and ionizing radiation may likewise affect its nature elemental composition of bitumen commonly reflects the nature of mineral deposits is is possible that in petroleum exploration trace metal abundances of bitumen may eventually allow prediction of crude oil types and volumes anticipated from a given source rock beside transition elements notably ni and v highly anomalous concentrations of u pt and au occur in some solid bitumens during the generation of petroleum from kerogen the trend in 13c is toward lighter values the opposite seems to occur when liquid petroleum is subjected to thermal cracking and or related processes yielding solid bitumen enriched in 13c and isotopically light methane in fact except for deasphalting and possibly some irradiation processes the result of thermal cracking oxidation water leaching inspissation drying and bacterial degradation of crude oil is that lower molecular weight hydrocarbons are removed leaving bitumen residues enriched in aromatic hydrocarbons heteroatomic compounds nso and 13c such phenomena are relevant to bitumen paragenesis in petroleum reservoir rocks to certain phanerozoic occurrences of multiple generations of bitumens and to bitumens in mineral deposits

convection initiation associated with a sea breeze front a gust front and their collision abstract the initiation of convection associated with a sea breeze front a gust front and their collision is analyzed using data collected in east central florida during the convection and precipitation electrification project in conjunction with satellite surface and rawinsonde information dual doppler radar derived winds are used to determine the three dimensional kinematic factors critical to storm development the gust front which emanated from storms on the western half of the peninsula propagated more rapidly and was deeper than the sea breeze front which originated from the east coast and was characterized by a distinctly scalloped appearance convection associated with the sea breeze front appeared to develop preferentially at the vertices of this scalloped pattern where there were enhanced regions of convergence and upward motion on the gust front a helmholtz shearing instability produced an organized configuration of convergence and updraft maxima along its length however these were

source characterization of highly mature pyrobitumens using trace and rare earth element geochemistry sinian paleozoic paleo oil reservoirs in south china abstract understanding the relationships between migrated hydrocarbons and source rocks under highly mature conditions i e pyrobitumen source correlation is a critical and challenging issue in the field of petroleum geology and geochemistry based on a case study of three sinian paleozoic paleo oil reservoirs from yunan and guizhou provinces south china we attempt to provide further understanding of this issue using trace and rare earth element ree geochemistry which can characterize the depositional setting organic input and rock provenance of source rocks results show that the bitumens from the three paleo oil reservoirs can be distinguished from each other using post archean australian shale paas normalized trace element distribution patterns ree distribution patterns hierarchal cluster analysis of element concentrations and redox and provenance sensitive elemental ratios e g v ni ni co ni mo zr cr la sc and la co pyrobitumen in the devonian xiaocaoba paleo oil reservoir is derived primarily from devonian source rocks representing a self sourced petroleum system and one stage hydrocarbon charging similarly pyrobitumen in the sinian jinsha yankong paleo reservoir also received a single fluid charge but the source is different and likely generated by contributions from both lower cambrian and sinian sources in contrast the bitumen in ordovician kaili luomian paleo reservoirs are indicated to have contributions from two different hydrocarbon sources and thus experienced two stages of hydrocarbon charging an early charge from lower cambrian source rocks and a later charge from permian source rocks the new trace and rare earth element method used in this study appears to be effective at providing a better understanding of the hydrocarbon source correlation under highly mature conditions the results improve our understanding of the complex hydrocarbon accumulation alteration evolution in the marine strata of south china which is a potential target for petroleum exploration

metal enrichment in bitumens from carboniferous hosted ore deposits of the british isles abstract bitumens from hydrothermal ore deposits and from other mineral showings in the lower carboniferous of the british isles are enriched in metals the enrichments are evident as micrometre scale inclusions of metalliferous ore minerals within the bitumens the bitumens were derived from hydrocarbon source rocks within the carboniferous and the metals are assumed to be derived from hydrothermal fluids a regional survey showed that there is some correlation between the metals present as inclusions in the bitumens and the metals present in the related host ore deposits showings the results suggest that the metal geochemistry of bitumens may be of value in ore exploration

alteration of solid bitumen by hydrothermal heating and thermochemical sulfate reduction in the ediacaran and cambrian dolomite reservoirs in the central sichuan basin sw china abstract solid bitumen in reservoir rocks is an allochthonous organic matter formed from bitumen or liquid hydrocarbons by various alteration processes in this study two types of altered solid bitumen have been identified in both the ediacaran dengying and cambrian longwangmiao formations in the central sichuan basin using petrographic microthermometric chemical and isotopic data the hydrothermally altered bitumen type 1 is associated with the pore filling saddle dolomite and quartz in which homogenization temperatures of some fluid inclusions are more than 10 c higher than the maximum burial temperature of the dengying formation it has various anisotropic textures with significantly high bireflectance values rbmax rbmin between 3 89 and 9 21 moreover the hydrothermal alteration led to 13c enrichment in the type 1 bitumen compared to the normally matured bitumen derived from the same source on the other hand the thermochemical sulfate reduction tsr altered bitumen type 2 has s c atomic ratios of up to approximately 0 06 the 34s values of type 2 bitumen are close to those of the carbonate associated sulfate and similar to the tsr derived h2s in the same reservoirs a strong negative correlation exists between s c atomic ratios and 13c values in the type 2 bitumen in the dengying formation which is interpreted as a result of an increasing incorporation of the 13c depleted ethanethiol into the bitumen during tsr this interpretation is consistent with the fact that the remaining ethane became isotopically heavier as tsr proceeded in addition the reactive sulfate for tsr was primarily derived from the hydrothermal sulfate such as barite this is evidenced by the replacement of hydrothermal barite by the 34s enriched pyrite and the small differences in 34s value between the barite and the type 2 bitumen or the tsr derived h2s in the same strata we suggest that tsr in the ediacaran and cambrian hydrocarbon reservoirs was probably initiated by hydrothermal activity