geothermometry and geochemistry of aqueous and oil bearing fluid inclusions from fateh field dubai abstract the production of oil from fateh field dubai is principally from the cretaceous mishrif formation porosity in the reservoir facies is partly occluded by late coarse grained calcite cement this cement contains both aqueous and oil bearing fluid inclusions fluid inclusion geothermometry was used to determine the temperature of that cement precipitation and calculate its timing relative to basin burial history these data were related to source rock maturation and from that the timing of oil migration was inferred to be oligocene to mid miocene which is geologically contemporaneous with early petroleum generation r 0 0 5 0 6 in the khatiyah source rock the fluid inclusions were analyzed by a thermal decrepitation gas chromatography technique benzene and low molecular weight paraffins were present and a series of normal alkenes was tentatively identified in the aqueous inclusions fresh oil inclusions consisted of c 1 n c 25 compounds whose light hydrocarbon composition was consistent with derivation from an early mature source rock altered petroleum residues detected in many mishrif samples are contained either in inclusions or along crystal cleavages these materials are the subject of an ongoing geochemical study of fateh field

hydrocarbon composition of authigenic inclusions application to elucidation of petroleum reservoir filling history abstract geochemical analysis of petroleum inclusions trapped in authigenic feldspar and quartz in the ula formation in the north sea ula oil field revealed a petroleum of markedly different composition than the oil presently in the reservoir using microthermometry and the burial history as a dating tools it is concluded that the petroleum in the k feldspar inclusions was present in the more porous and permeable parts of the ula formation as early as 45 75 my bp when the field was at a depth of about 1 0 1 5 km as compared with the current depth of 3 4 km this early petroleum which was trapped as inclusions in authigenic k feldspar shows a distinctly different distribution of tricyclic terpanes and pentacyclic triterpanes from that of the current petroleum charge in the ula formation which was derived from the mandal formation source rock in late neogene time molecular parameters show that the oil in the k feldspar inclusions is significantly less mature than the crude oil in the present reservoir the approximate 90 c temperature increase occurring after entrapment of the early petroleum in kfeldspar the field is currently at 143 c appears not to have reset the low maturity signature of the oil in the k feldspar inclusions this could suggest that the temperature in the inclusions is too low for isomerization selective thermal degradation to occur lack of catalysts or that there are other controls on the ratio of some of these parameters still parameters like the ratio of c21 to c28 triaromatic steroids and those based on dimethyl and trimethyl naphthalenes are comparatively similar in both the inclusions and in the reservoir crude the oil inclusions in authigenic quartz and albite formed from about 10 my bp burial depth 2 5 km until the present burial depth 3 4 km are interpreted as representing a palaeo petroleum charge having a composition intermediate between the oil found in k feldspar inclusions and the oil charge in the present reservoir our data suggest strongly that the petroleum trapped in the inclusions in quartz and plagioclase represents progressive dilution of the early reservoired oil now found only in k feldspar inclusions with oil from the mandal formation analysis of solution gas in these inclusions suggests that the first petroleum associated gas to arrive at the trap from the progressively maturing mandal formation had a much wetter composition than the current reservoir solution gas to explain the present comparatively drier and isotopically lighter reservoir solution gas composition the inference is made that there has been a recent during formation of k feldspar inclusions 45 75 my bp maturation of the upper jurassic mandal formation the main source rock in this region was limited possibly to the graben axis this suggests that the petroleum found in the k feldspar inclusions was most likely derived from a deeper post caledonian palaeozoic formation

kinematic model for postorogenic basin and range extension the raft river extensional shear zone is exposed in the albion raft river grouse creek metamorphic core complex several studies of ductile deformation have shown that it accommodated crustal stretching in tertiary time during late orogenic collapse of the thickened cordilleran crust progressive deformation that results from mixed pure and simple shear produces a complex strain pattern along the shear zone the authors propose a numerical kinematic model that relates strain variations in the shear zone to the different amounts of extension between the brittlely extended upper plate rocks and the undeformed lower plate rocks a possible hypothesis for postorogenic crustal extension involves diffuse heterogeneous extension and flow in the ductile lower crust and localized extensional shear zones in the middle and upper crust

petroleum generation and charge history of the northern dongying depression bohai bay basin china insight from integrated fluid inclusion analysis and basin modelling abstract the petroleum generation and charge history of the northern dongying depression bohai bay basin was investigated using an integrated fluid inclusion analysis workflow and geohistory modelling one and two dimensional basin modelling was performed to unravel the oil generation history of the eocene shahejie formation es3 and es4 source rocks based on the reconstruction of the burial thermal and maturity history calibration of the model with thermal maturity and borehole temperature data using a rift basin heat flow model indicates that the upper interval of the es4 source rocks began to generate oil at around 35 ma reached a maturity level of 0 7 ro at 31 30 ma and a peak hydrocarbon generation at 24 23 ma the lower interval of the es3 source rocks began to generate oil at around 33 32 ma and reached a maturity of 0 7 ro at about 27 26 ma oil generation from the lower es3 and upper es4 source rocks occurred in three phases with the first phase from approximately 30 20 ma the second phase from approximately 20 5 ma and the third phase from 5 ma to the present day the first and third phases were the two predominant phases of intense oil generation samples from the es3 and es4 reservoir intervals in 12 wells at depth intervals between 2677 7 m and 4323 0 m were investigated using an integrated fluid inclusion workflow including petrography fluorescence spectroscopy and microthermometry to determine the petroleum charge history in the northern dongying depression abundant oil inclusions with a range of fluorescence colours from near yellow to near blue were observed and were interpreted to represent two episodes of hydrocarbon charge based on the fluid inclusion petrography fluorescence spectroscopy and microthermometry data two episodes of oil charge were determined at 24 20 ma and 4 3 ma respectively with the second episode being the predominant period for the oil accumulation in the northern dongying depression the oil charge occurred during or immediately after the modelled intense oil generation and coincided with a regional uplift and a rapid subsidence suggesting that the hydrocarbon migration from the already overpressured source rocks may have been triggered by the regional uplift and rapid subsidence the expelled oil was then charged to the already established traps in the northern dongying depression the proximal locations of the reservoirs to the generative kitchens and the short oil migration distance facilitate the intimate relationship between oil generation migration and accumulation

weakening of rock salt by water during long term creep the rheological properties of rock salt are of fundamental importance in predicting the long term evolution of salt based radioactive waste repositories and strategic storage caverns and in modelling the formation of salt diapirs and associated oil traps1 2 the short term high stress rheology of rock salt is well known from laboratory experiments however extrapolation to appropriately low stresses fails to predict the rapid flow seen in certain natural structures furthermore experiments have failed to reproduce the recrystallized microstructure of naturally deformed salt here we report experiments indicating that the above discrepancies can be explained by taking into account the influence of trace amounts of brine trace brine is always present in natural salt but sometimes escapes during experiments our tests on dry dilated salt show more or less conventional dislocation creep behaviour but brine bearing samples show marked weakening at low strain rates this is associated with dynamic recrystallization and a change of deformation mechanism to solution transfer creep because natural rock salt always contains some brine these results cast substantial doubt on the validity of presently accepted dislocation creep laws for predicting the long term rheological behaviour of salt in nature

hydrocarbon water interactions during brine migration evidence from hydrocarbon inclusions in calcite cements from danish north sea oil fields abstract crude oils in primary and secondary fluid inclusions in calcite from fractures in seven offshore oil fields associated with diapiric salt structures in the danish sector of the north sea were analyzed by capillary column gas chromatography and compared with crude oils produced from the same reservoirs oils from fluid inclusions in all fields show evidence of biodegradation decreased n c17 pristane and n c18 phytane ratios and loss of n c7 2 methyl hexane and 3 methyl hexane relative to methyl cyclohexane and water washing absence of benzene and depletion of toluene some oils in inclusions are extremely enriched in c6 and c7 cyclic alkanes suggesting that these samples contain hydrocarbons exsolved from ascending hotter formation waters compared to inclusion oils the produced oils are less biodegraded but are water washed indicating that both types of oil interacted with large volumes of formation water the carbon isotopic composition of the calcite host of the fluid inclusions in the dagmar and skjold fields is as light as 16 5 pdb and the sulfur isotopic composition of pyrite in and adjacent to the calcite veins in the skjold field is as light as 39 6 cdt indicating that biodegradation of the oils was a source of some of the carbon in the calcite and sulfate reduction was the source of sulfur for the pyrite the evidence for microbial degradation of petroleum is consistent with present day reservoir temperatures 65 96 c but is not consistent with previous estimates of the temperatures of calcite vein filling 95 130 c which are much higher than the temperatures of known occurrences of biodegraded oil

uv raman spectroscopy of hydrocarbon bearing inclusions in rock salt from the dongying sag eastern china abstract compositions of hydrocarbon bearing inclusions in rock salt halite from the shahejie formation in the dongying sag bohai bay basin eastern china have been analysed by raman spectroscopy coupled with a 244 nm uv laser source the fluorescence effect caused by the conventional visible laser excitation of the aromatic fractions of hc bearing inclusions can be effectively avoided six types of hc bearing inclusions belonging to two generations have been identified in halite according to their hydrocarbon types and petrographic characteristics the presence of hc bearing inclusions in halite provides evidence of crystal fracturing and healing plastic deformation and dynamic recrystallization of rock salt in the dongying sag this proves that rock salt may have repeatedly lost and then recovered its sealing capacity during two stages of oil emplacement water and hydrocarbons were detected by uv raman spectroscopy in the studied samples in both hc bearing inclusions and aqueous inclusions these results are important for understanding the formation conditions of these fluid inclusions and the interactions between the formation water and petroleum in reservoirs our results show that uv raman spectroscopy has a potential to become a powerful tool for analyzing hydrocarbon bearing fluid inclusions trapped in various elements of a petroleum system

raman spectroscopy as a tool for the non destructive identification of organic minerals in the geological record abstract organic minerals can be considered as a forgotten group of organic components in the geological record they are salts of organic acids originating directly in plant metabolic processes pure crystalline terpenes formed from precursor conifer decomposition products and polycyclic aromatic hydrocarbons originating in the accumulation of fractions generated by natural high temperature distillation from specific precursors the presence of some of these minerals in quaternary or tertiary continental sedimentary environments in soils and peats is known as are rare occurrences in lignite shales and other rocks from older geological formations raman spectral signatures have been identified for mellite the hydrated aluminium salt of benzene hexacarboxylic acid the terpenoids fichtelite norabietane and hartite phyllocladane as well as for idrialite a complex polycyclic aromatic hydrocarbon mineral the survival of organic minerals such as oxalates terpenoid hydrocarbons and aromatic minerals in the geological record is important for an appreciation of the diversity of molecular compounds that need to be assessed in the search for life detection signatures in terrestrial and extraterrestrial scenarios

extensional collapse in the neoproterozoic aracuai orogen eastern brazil a setting for reactivation of asymmetric crenulation cleavage the aracuao orogen of eastern brazil is one of many brasiliano pan african orogens formed during the neoproterozoic assembly of gondwana its western edge bordering the sao francisco craton is the serra do espinhaco fold thrust belt in which top up to the west reverse sense faults west verging folds f1 and east dipping spaced to phyllitic cleavage s1 developed we have found that the kinematics of deformation changes markedly at the hinterland margin of this fold thrust belt here beneath a plateau known as the chapada acaua metadiamictite and fine grained pelitic schist comprise an east dipping belt that contains an assemblage of structures indicative of top down to the east normal sense shear this assemblage includes a cascade of f2 folds that refold f1 folds and verge down the dip of the belt s enveloping surfaces vertical tension gashes and top down to the east rotated clasts based on the presence of these structures we propose that the plateau exposes a regional scale normal sense shear zone here called the chapada acauashear zone casz because f2 folds refold f1 folds normal sense shear in the casz occurred subsequent to initial west verging thrusting considering this timing of motion in the casz we suggest that the zone accommodated displacement of the internal zone of the aracuao orogen down relative to its foreland fold thrust belt and thus played a role in extensional collapse of the orogen the casz trends parallel to preserved thrusts to the west and thus may represent an inverted thrust fault notably throughout the casz s1 schistosity has been overprinted by a pervasive west dipping asymmetric crenulation cleavage s2 the sigmoid shape of s1 surfaces in s2 microlithons require that slip on each s2 surface was top down to the west s2 cleavage is axial planar to the down dip verging f2 folds based on its geometry we suggest that s2 cleavage initiated either as an antithetic extensional crenulation cleavage during reverse sense shear or as a near vertical asymmetric crenulation cleavage formed during east west shortening of a preexisting east dipping schistosity subsequent normal sense shear in the casz reactivated this cleavage causing clockwise rotation of s2 domains as viewed looking along strike to the north in a manner similar to that of rotational bookshelf faults such movement could have accommodated concomitant vertical flattening of the casz during extensional collapse

organic inclusions in salt part 2 oil gas and ammonium in inclusions from the gabon margin abstract organic inclusions have been found in a salt diapir south of port gentil in the north subbasin of the gabon margin two main types of organic inclusions are described type 1 gas rich ch4 and co2 oil inclusions located in recrystallized halite associated with a complex mineral daughter paragenesis anhydrite quartz k feldspar dolomite ammonium sylvite and carnallite 1 and 2 5 molar nh4cl respectively the oil is essentially aliphatic with some aromatic content the composition being characteristic of mature oil the different methane c2 ratios in the gas and oil phases indicate an internal pressure close to 200 bars which is compatible with hydrostatic pressure at sampling depth homogenization temperatures of two phase hydrocarbon inclusions inside dolomite daughter crystals have been measured th 113 c type 2 organic inclusions are located in healed fracture planes in recrystallized halite and contain aliphatic oil the brine content is high and no gases have been detected different alkane compositions occur in different fracture planes type 2 inclusions correspond to injections of mature oil into halite fracture systems at low temperature 60 c comparisons between fluid inclusions in halite occurring in the bresse area france and in the north subbasin of the gabon margin help one to follow carbon and nitrogen cycles from diagenesis to catagenesis the organic inclusions hosted in salt rocks reflect the geochemical reactions that have occurred in the salt over time

plio quaternary thin skinned tectonics along the crustal front flexure of the southern central andes a record of the regional stress regime or of local tectonic driven gravitational processes we present here a record of plio pleistocene deformations above the flexural front of the southern central andes of argentina we combine a seismic profile with structural and geomorphological observations to show that thin skinned extension located on top of the crustal front flexure is coeval with thin skinned shortening at the toe of the topographic bulge the seismic line shows that a flat zone with no internal deformation separates the stretched and shortened domains such features are usually interpreted as the result of strike slip faulting along basement faults or tangential longitudinal strain folding in the soft sedimentary cover above crustal bending we propose an alternative linking extension at the apex of the crustal anticline to basal contraction by the downslope translation of a rigid thin nappe of sediments 30 30 km2 in area above evaporites at a depth of 700 900 m the size of such a process is unusually large onshore 630 810 km3 but mimics the gravity gliding observed in deltas and passive margins since this process disconnects zones with a shallow stress field from deeper crustal levels it could allow extension above a compressive deformation front and should not be interpreted merely as a record of the crustal stress regime large scale gravity gliding of the cover down the slope of a structural high could also explain some of the extension observed in mountain hinterlands

late orogenic extension in mountain belts insights from the basin and range and the late paleozoic variscan belt from two examples of orogenic domains some general mechanisms significant of late orogenic tectonic processes in mountain belts are characterized the basin and range province and the variscan belt in the french massif central have both suffered important compressional orogenic crustal thickening and the results of late orogenic processes can be observed in the field both areas are covered by deep seismic profiling providing constraints on the geometry of a crust which has been restored to a normal thickness late orogenic features from the two domains are compared at different scales and their tectonic significance for extension mechanisms is discussed at the scale of the orogenic domains the most prominent tectonic features are the metamorphic core complexes mcc which expose deformed rocks from the middle crust generally affected by high temperature low to medium pressure metamorphism partial melting and widespread granite emplacement in these mcc large scale extensional shear zones present an intense mylonitic deformation characterized by low dipping foliations and pervasive stretching lineations they show a complete evolution from early deep seated ductile deformation generally achieved under high temperature low to medium pressure metamorphism to a late shallow brittle stage characterized by cataclastic deformation the late detachment stage generally controls the development of asymmetrical extensional sedimentary basins filled by continental deposits two main geometries of mcc are defined that are characterized by differing geometry and kinematics of low angle shear zones in the first case two low angle shear zones with opposite vergence develop along the flanks of a roughly symmetrical mcc often one system is dominant over the other the second geometry characterizes asymmetrical mcc bounded by a single normal shear zone which is upwarped during uplift and doming of the core caused by tectonic denudation detailed strain analysis performed in several extensional shear zones shows that the deformation regime is heterogeneous and results from general noncoaxial flow deformation along the shear zones evolves progressively from slight homogeneous pure shear strain to intense heterogeneous noncoaxial shear strain strain distribution within the lower crust is less well constrained by field observation however analogies between cocorp and ecors deep seismic reflection profiles give important constraints on crustal structure wide zones of highly subhorizontally layered lower crust and a flat high amplitude reflection moho characterize both evolved orogenic domains suggesting that major deformations and flow occur within the lower crust during extension a kinematic model involving heterogeneous crustal deformation and regional scale flow fits relatively well with late orogenic structures observed in continental domains a weak hot upper mantle allows large scale flow of lower crust material from zones of deep ductile extension to uplifted domains of upper crustal denudation heterogeneous strain is accommodated by low angle extensional shear zones from localized zones of extension in the brittle crust to ductile lower crust combined pure and simple shear occurs along localized shear zones whereas at the scale of the whole lithosphere deformation nearly corresponds to a vertical pure shear such deformation processes which affect a thick and hot crust seem to be common in both compared domains suggesting that late orogenic extensional processes are slightly dependent of the type of contractional tectonics thus as much in the andean type west american cordilleran belt as in the collision type variscan belt late orogenic processes produced similar extensional features

polyphase thermal evolution in the infra cambrian ara group south oman salt basin as deduced by maturity of solid reservoir bitumen petrographic and organic geochemical analyses on solid reservoir bitumen from the late precambrian to early cambrian ara group indicate polyphase thermal evolution in the south oman salt basin sosb the ara group constitutes a complex petroleum system in the deep subsurface 3 5 km of interior oman salt diapirs encase isolated partly highly overpressured carbonate bodies intra salt stringers which represent a predominantly self charging hydrocarbon system a large number of stringer cores show that reservoir quality is decreased by the presence of solid reservoir bitumen by using different microscopy techniques this solid reservoir bitumen has been identified within pores pore throats and microfractures of the carbonates solid bitumen reflectance measurements brr were converted to vitrinite reflectance vrr using a new improved calibration vitrinite reflectance geothermometry shows that maximum paleo temperatures have a highly heterogeneous distribution paleo temperatures of 380 c were obtained from coke like solid reservoir bitumen which most likely formed from thermal cracking of oil in our model this process is related to hydrothermal fluids deriving from deeper pre salt strata of the sosb which entered the intra salt carbonate stringers during times of basement tectonic activity via hydrofractures this caused the formation of high maturities pyrobitumens in close vicinity to the fractures and precipitation of migrabitumens with increasing distance to the ht source which is supported by the geochemical composition of the solid reservoir bitumens the influx of these fluids into the carbonate stringers is considered to represent a major contribution to their strong overpressures 2007 elsevier ltd all rights reserved

hydrocarbon fluid inclusions in the argo salt offshore canadian atlantic margin1 fluid inclusions hosted in rock salt from the triassic argo formation in the canadian atlantic continental margin were studied to investigate the nature and origin of petroleum fluids in them incl

petroleum inclusions in sedimentary basins systematics analytical methods and applications abstract fluid dynamics in sedimentary basins is of tremendous interest both from a scientific and an economic point of view integration between fluid inclusion and present day fluid data provides the time aspect necessary for reconstruction of fluid flow paths and can be used for mapping fluid dynamics both on a regional basin scale or on the more local scale of petroleum reservoirs this paper presents a review of analytical and modelling methods for petroleum in fluid inclusions essentially four types of data for petroleum inclusions can be established through analysis and modelling 1 textures which give indirect information of the time aspect 2 fluid composition 3 fluid properties and 4 pressure temperature of trapping during the last decade development of analytical methods for determination of inclusion fluid compositions has taken place traditional correlation studies for characterisation of maturity and source facies may now therefore include fluid inclusion data the development has also been directed towards an improved understanding of the physical properties of petroleum inclusions although these methods are in their early stages concerning precision and accuracy data necessary for fluid flow modelling such as fluid densities viscosities pressure and temperature can be estimated

laser ablation gc ms analysis of oil bearing fluid inclusions in petroleum reservoir rocks abstract the hydrocarbon composition of co occurring blue and yellow fluorescing fluid inclusions fis in ordovician reservoirs of the tarim basin nw china have been separately analyzed by laser microprobe gas chromatography mass spectrometry gc ms using a 193 nm excimer laser to drill through the host quartz a newly designed gc inlet system enabled detection of c4 c30 hydrocarbons extending the molecular weight significantly beyond the c21 limit of previous online laser based hydrocarbon analysis of oil inclusions the blue fluorescing inclusions contain notably higher proportions of aliphatic hydrocarbons e g n alkanes cycloalkanes and gaseous range products whereas the yellow fluorescing inclusions contain relatively more aromatic hydrocarbons e g alkylnaphthalenes hydrocarbon based parameters also indicate that the blue fluorescing inclusions are of higher thermal maturity than the yellow fluorescing inclusions consistent with maturity estimates based on fluorescence colors the compositional differences of the co occurring inclusions are indicative of different oil types and charge events this highlights the capacity of the new laser ablation technology to separately analyse specific inclusions amongst a mixture of inclusions of different fluorescing colors in the future integration of this new compositional detail with other inclusion and reservoir data will help reconstruct the oil charge history of the tarim basin

kinematics of orogenic collapse in the variscan pyrenees deduced from microstructures in porphyroblastic rocks from the lys caillaouas massif in the pyrenees a phase of bulk vertical shortening d3 is indicated by a horizontal crenulation cleavage s3 which is developed in a pre existing schistosity s2 porphyroblasts of the lys caillaouas massif regionally preserve 1 1 the initial pre d3 orientation of s2 in the form of a vertical and e w trending preferred orientation of their inclusion trails 2 2 a vertical l2 stretching lineation defined by the elongation of the inclusions these data are consistent with n s compression and crustal thickening during d2 the angle between the inclusion trails s2 i and the external schistosity s2 e records the subsequent rotation of s2 from vertical to gently dipping orientations at higher crustal levels s2 remained steep suprastructure and little d3 deformation is evidenced with depth d3 deformation progressively intensifies and zones can be distinguished with opposite dip directions of s2 opposite apparent porphyroblast rotation senses and opposite f3 crenulation asymmetries these micro structures on a n s section through the lys caillaouas and the garonne dome massifs record a regional partitioning of bulk coaxial vertical shortening this deformation partitioning was probably controlled by a not exposed gneiss dome which behaved relatively rigid as compared to its metasedimentary cover in zones of non coaxial d3 deformation s2 was extended reactivated and forms the dominant schistosity where d3 was locally more coaxial s2 was shortened isoclinally crenulated and s3 forms the macroscopic cleavage the fact that d3 extension in the lys caillaouas massif immediately followed d2 compression and that similar extension is recorded in large parts of the variscan foldbelt suggests gravitational collapse of a thickened orogen this is consistent with the flattening type of d3 strain recognized in a number of pyrenean variscan massifs peak high t low p metamorphic conditions coincide with the onset of orogenic extension when very little crustal thinning could have been accomplished yet this suggests that heat induced strain softening within the orogen may have triggered its collapse

molecular analysis of petroleum in fluid inclusions a practical methodology a method is described for extracting the petroleum from petroleum bearing fluid inclusions hosted in the diagenetic cements of sedimentary rocks whilst minimising contamination from petroleum in the pore space a clean up technique involving the addition of extraction standards to the rock prior to analysis has been developed that allows increased confidence that the hydrocarbons extracted are only from included petroleum and are not mixtures of included petroleum and petroleum or other organic material adhering to the surface of the host minerals within the sample replicate quantitative analyses indicate that the technique produces highly reproducible results the problems of analysing included petroleum and the clean up method development are discussed and examples of analyses of included petroleums from carbonate reservoir and carrier units are given

a pulsed extension model for the neogene recent e w trending alasehir graben and the ne sw trending selendi and gordes basins western turkey abstract we have developed a significant body of new field based evidence relating to the history of crustal extension in western turkey we establish that two of the ne sw trending basins in this region the gordes and selendi basins whose sedimentary successions begin in the early miocene are unlikely to relate to late stage alpine compressional orogeny or to e w extension of tibetan type grabens as previously suggested we argue instead that these basins are the result of earlier late oligocene low angle normal faulting that created approximately n s scoop shaped depressions in which clastic to lacustine and later tuffaceous sediments accumulated during early mid miocene time separated by elongate structural highs these basins were later cut by e w trending plio quaternary normal faults that post date accumulation of the neogene deposits in addition we interpret the alasehir gediz graben in terms of two phases of extension an early phase lasting from the early miocene to the late miocene and a young plio quaternary phase that is still active taking into account our inferred earlier phase of regional extension we thus propose a new three phase pulsed extension model for western turkey we relate the first two phases to roll back of the south aegean subduction zone and the third phase to the westward tectonic escape of anatolia

fluid inclusion petrography and tectonic burial history of the al ali no 2 well evidence for the timing of diagenesis and oil migration northern oman foredeep cores cut in shallow marine lower and middle cretaceous carbonates in the al ali no 2 well umm al qaiwain united arab emirates display a five stage sequence of calcite cementation fracturing and stylolitization these stages are correlated with the tectonic history of the northern oman orogeny occurrence of fluorescent hydrocarbon fluid inclusions is restricted to stage 2 and stage 3 fracture filling calcites that are crosscut by stylolites stylolite formation during rapid burial beneath abyssal campanian foredeep sediments restricts hydrocarbon migration to post mid cenomanian and pre mid campanian time

raman microspectrometry of fluid inclusions abstract for many kinds of fluid inclusions the coupling of microthermometry and raman microspectrometry is still the only viable option to obtain compositions of single fluid inclusions a review is given on the basis of 16 years of experience and helped with about 120 references of the instrumentation analytical conditions and methodology of the application of raman microspectrometry to gaseous aqueous and hydrocarbon inclusions and their daughter minerals

petroleum and aqueous inclusions from deeply buried reservoirs experimental simulations and consequences for overpressure estimates abstract synthetic hydrocarbon and aqueous inclusions have been created in the laboratory batch reactors in order to mimic inclusion formation or re equilibration in deeply buried reservoirs inclusions were synthesized in quartz and calcite using pure water and mexican dead oil or n tetradecane c14h30 at a temperature and pressure of 150 c and 1 kbar one phase hydrocarbon inclusions are frequently observed at standard laboratory conditions leading to homogenization temperatures between 0 and 60 c uv epifluorescence of mexican oil inclusions is not uniform blue and green yellow colored inclusions coexist however no clear evidence of variations in fluid chemistry were observed homogenization temperatures were recorded and the maxima of th plotted on histograms are in good agreement with expected th in a range of 6 c broad histograms were reconstructed showing non symmetrical th distributions over a 20 c temperature range centered on the expected th this histogram broadening is due to the fragility of the fluid inclusions that were created by re filling of pre existing microcavities such th histograms are similar to th histograms recorded on natural samples from deeply buried carbonate reservoirs th values lower than those expected were measured for hydrocarbon inclusions in quartz and calcite and for aqueous inclusions in calcite however the results confirm the ability of fluid inclusions containing two immiscible fluids to lead to pt reconstructions even in overpressured environments

historical rates of salt marsh accretion on the outer bay of fundy we examine rates of salt marsh accumulation in three marshes of the outer bay of fundy at each marsh we selected a site in the high marsh with similar vegetation and thus similar elevation accretion rates were estimated by 137 cs 210 pb and pollen stratigraphy to estimate rates of change over periods of 30 100 and 170 years respectively these rates are compared with records from the two closest tide gauges saint john new brunswick and eastport maine to assess the balance of recent marsh accretion and sea level change averaged marsh accretion rates have ranged from 1 3 0 4 to 4 4 1 6 mm year 1 over the last two centuries recent rates are similar to the rate of sea level change recorded at eastport maine suggesting that they are in step with recent sea level change but very sensi tive to short term variation in relative sea level based on the pollen stratigraphy in the marsh sediments the marsh ac cretion rate was higher during the late 18th to early 19th century higher rates probably were due to local increases in relative sea level as a result of neotectonic activity and may have been enhanced by increased sediment deposition through ice rafting

estimation and uncertainty of recent carbon accumulation and vertical accretion in drained and undrained forested peatlands of the southeastern usa the purpose of this study was to determine how drainage impacts carbon densities and recent rates past 50 years of vertical accretion and carbon accumulation in southeastern forested peatlands we compared these parameters in drained maple gum mapl atlantic white cedar cdr and pocosin poc communities in the great dismal swamp national wildlife refuge gds of virginia north carolina and in an intact undrained cdr swamp in the alligator river national wildlife refuge ar of north carolina peat cores were analyzed for bulk density percent organic carbon and 137cs and 210pb an uncertainty analysis of both 137cs and 210pb approaches was used to constrain error at least partially related to mobility of both radioisotopes gds peats had lower porosities 89 6 sd 1 71 versus 95 3 0 18 and higher carbon densities 0 082 0 021 versus 0 037 0 009 g c cm 3 than ar vertical accretion rates 0 10 0 56 cm yr 1 were used to estimate a time period of 84 362 years for reestablishment of peat lost during the 2011 lateral west fire at the gds carbon accumulation rates ranged from 51 to 389 g c m 2 yr 1 for all sites in the drained gds versus intact ar cdr sites carbon accumulation rates were similar with 137cs 87gds versus 92ar g c m 2 yr 1 and somewhat less at the gds than ar as determined with 210pb 111gds versus 159ar g c m 2 yr 1 heightened productivity and high polyphenol content of peat may be responsible for similar rates of carbon accumulation in both drained and intact cdr peatlands

the migration of fluid filled grain boundaries in recrystallizing synthetic bischofite first results of in situ high pressure high temperature deformation experiments in transmitted light the effect of fluids on recrystallization behaviour is well known however the detailed microscale distribution of fluid in grain boundaries and the influence of fluid on grain boundary migration are still unresolved in this study in situ deformation experiments in transmitted light microscopy were undertaken as this allows continuous and direct observation of the whole range of processes involved in fluid assisted grain boundary migration a new see through deformation apparatus was developed to enable the control of fluid pressure bischofite containing small amounts of aqueous fluid was deformed at temperatures between 50 and 90 c over a range of fluid pressure from 0 5 to 1 mpa and strain rates of 5 10 6 to 1 10 4 s 1 the rates of grain boundary migration were measured at different temperatures and strain rates detailed observations during and after the deformation illustrate the evolution of migrating fluid filled grain boundaries and show that the incorporation of fluids from inclusions as well as their pinch off is dependent on the grain boundary velocity the thickness of the grain boundary and the size and shape of the inclusions direct evidence is presented for the contraction of the grain boundary fluids into isolated inclusions after equilibrium conditions are attained

fluid inclusions in sedimentary and diagenetic systems abstract some of the major problems in sedimentary geology can be solved by using fluid inclusions in sedimentary and diagenetic minerals important fluids in the sedimentary realm include atmospheric gases fresh water of meteoric origin lake water seawater mixed water evaporated water formation waters deep in basins oil and natural gas preserving a record of the distribution and composition of these fluids from the past should contribute significantly to studies of paleoclimate and global change research is essential for improving understanding of diagenetic systems and provides useful information in petroleum geology applications of fluid inclusions to sedimentary systems are not without their complexities some fluid inclusions exposed to natural conditions of increasing temperature may be altered by thermal reequilibration which results in stretching or leakage and refilling of some fluid inclusions similarly overheating in the laboratory can also cause reequilibration of fluid inclusions so fluid inclusions from the sedimentary realm must be handled carefully and protected from overheating natural overheating of fluid inclusions must be evaluated through analysis of the most finely discriminated events of fluid inclusion entrapment fluid inclusion assemblages fia consistency in homogenization temperatures within a fluid inclusion assemblage consisting of variably sized and shaped inclusions is the hallmark of a data set that has not been altered through thermal reequilibration in contrast fluid inclusion assemblages yielding variable data may have been altered through thermal reequilibration if a fluid inclusion assemblage has not been altered by thermal reequilibration its fluid inclusions may be useful as geothermometers for low and high temperature systems or useful as geobarometers applicable throughout the sedimentary realm if a fluid inclusion assemblage has been altered partially by thermal reequilibration techniques for distinguishing between altered and unaltered fluid inclusions may be applied in studies of global change fluid inclusions can be used as sensitive indicators of paleotemperature of surface environments fluid inclusions also preserve microsamples of ancient seawater and atmosphere the analysis of which could figure prominently into discussions of past changes in chemistry of the atmosphere and oceans in petroleum geology fluid inclusions have proven to be useful indicators of migration pathways of hydrocarbons they can delineate the evolution of the chemistry of hydrocarbons and they remain important in understanding the thermal history of basins and relating fluid migration events to evolution of reservoir systems in studies of diagenesis fluid inclusions can be the most definitive record most diagenetic systems are closely linked to temperature and salinity of the fluid thus fluid inclusions are sensitive indicators of diagenetic environments

strain patterns within the late variscan granitic dome of velay french massif central the velay granites are intruded as a late variscan dome in the french massif central strain patterns within the velay granites reflect the geometry and kinematics of late carboniferous deformation at the site of final emplacement the internal deformation developed during granitic magmatism is not homogeneously distributed from inner to outer zones increasing deformation is marked by changes from high temperature foliations to s c orthogneisses strain concentration at the margins reflects a strength contrast due to cooling and subsequent magma hardening according to the internal strain field two zones can be distinguished in the velay dome i a central and southern zone where concentric patterns indicate a southward expansion of granites and ii a northern zone where the lateral expansion is limited and combined with top to the north extensional shearing along the mont pilat detachment zone and high temperature wrenching these asymmetric strain patterns relate to the expansion and deformation of granites emplaced below a detachment fault during the uplift of a thickened area post thickening combination of extensional and wrench tectonics is inferred

diagenesis and reservoir quality evolution of the eocene sandstones in the northern dongying sag bohai bay basin east china abstract the eocene sandstones in the northern dongying sag bohai bay basin china are reservoirs for large accumulations of hydrocarbons the sandstones are mainly lithic arkoses and feldspathic litharenites texturally and compositionally immature these sandstones have a wide range of porosity 0 4 37 and permeability 0 004 6969 md and show an overall decrease in reservoir quality from 1500 m to 5000 m below sea level the reduction in reservoir quality is a product of several digenetic processes these include compaction precipitation of dolomite and calcite in eodiagenetic stage compaction feldspar dissolution precipitation of quartz cements and clays kaolin and illite and precipitation of ferrocalcite and ankerite in mesodiagenetic stage mineral distribution pattern and isotopic composition suggest carbonate cements in sandstones originate from sources outside the sandstones carbonate cementation together with compaction reduced the sandstones porosity and permeability significantly in a sandstone bed marginal sandstones with distance to sandstone mudstone interface less than one meter always have lower porosity than central sandstones as burial depth exceeds 4000 m marginal sandstones have very low porosities 2 m can be potential effective reservoirs feldspar dissolution and precipitation of clays and quartz cements have little impact on absolute porosity mineral distribution pattern and quantitative data show that leached feldspars are the internal source of authigenic quartz and clays in sandstones and the volume difference between feldspar secondary porosity and related authigenic cements is generally less than 0 25 however although there is little or no net import of matter to the sandstones the pore architecture changes dramatically primary macropores are lost as clays and quartz precipitate while the proportion of microporosity increases occurring mainly between clay crystals the overall result is that permeability is significantly degraded

thin viscous middle crust and evolving fault distribution during continental rifting insights from analog modeling experiments abstract analog modeling of continental rifting assuming a crustal scale jelly sandwich like rheology was carried out to test the mechanical effect of varying the absolute thickness of a weak viscous middle crust silicone layer interbedded between a brittle upper crust sand layer and a strong lower crust results consistently show a delocalization of the brittle deformation i e a uniform scattering of the faults throughout the upper brittle layer this effect is interpreted to be associated with pressure driven flow in the viscous layer caused by the tectonic collapse of upper brittle fault blocks into the viscous substratum a reduction of the overall viscous layer thickness increases its resistance to accommodate internal thickness variations which promotes delocalization of the fault pattern in the upper brittle layer our results contribute to the understanding of the mechanics of the so called upper plate paradox a large scale structure often recognized at non volcanic rifted margins a thin viscous middle crust provides means of decoupling the deformation affecting upper and lower crust during rifting on one hand this promotes a uniform scattering of faults throughout the upper brittle crust on the other hand it allows for a strong localization of the deformation in lower crust and upper mantle expressed by the lithospheric necking in the rift center

constraining the oil charge history of the south pepper oilfield from the analysis of oil bearing fluid inclusions abstract the south pepper oilfield located in the barrow sub basin on the nw margin of the australian continent has experienced a multi phase charge history abundant oil bearing fluid inclusions are present in samples from within the current gas cap suggesting that an oil column existed prior to gas this palaeo oil gas leg fi oil has ts tm and c29 c30 hopane ratios of 1 and the c35 homohopanes are a significant proportion of the extended homohopanes it has lower pr ph and diasterane sterane ratios than the currently reservoired live oil and contains gammacerane a series of peaks tentatively identified as c30 to c34 17 h 30 norhopanes and a large amount of 2 methylhopanes collectively geochemical analysis of the gas leg fi oil suggests that it was generated from a less mature more calcareous source rock deposited under more reducing conditions than the upper jurassic dingo claystone the main source of the live oil in addition the presence of c30 dinosteranes in the gas leg fi oil provides a triassic or younger age constraint this makes palaeozoic carbonates an unlikely source possible source intervals for the gas leg fi oil are thin lower jurassic limestones and marls which occur at the base of the lower dingo claystone or a thin limestone unit the cunaloo member at the base of the triassic locker shale samples from within the present oil leg also contain abundant oil inclusions consistent with high oil saturations at the present day however these oil inclusions exhibit different fluorescence colours suggesting they represent a second oil charge geochemically the oil leg fi oil has an intermediate composition between the live oil and the gas leg fi oil suggesting that gas charge displaced the first oil charge samples of which were preserved as fluid inclusions in the oil leg sample biodegradation of the first oil charge indicated by the presence of 17 h 25 norhopanes in the currently reservoired live oils can be attributed to the ingress of meteoric waters probably during sub aerial exposure of the basin margin during miocene wrenching changing environmental conditions curtailed bacterial activity and allowed unaltered oil sourced from the dingo claystone to accumulate below the gas cap and mix with the biodegraded residues of the first oil charge to achieve the live oil composition the biodegradation event must have preceded the second charge as the live oil contains compounds such as n alkanes which would have been removed had alteration occurred after the second charge complex charge histories are common and the analysis of palaeo oils trapped within fluid inclusions provides the opportunity to achieve a more comprehensive assessment of hydrocarbon charge

using petroleum inclusions to trace petroleum systems a review abstract petroleum bearing fluid inclusions are small encapsulations of oil and gas that offer an invaluable opportunity to better constrain the evolution of petroleum systems insights into palaeo fluid compositions complement observations on present day fluid compositions which represent only the end point of complex cumulative processes throughout basin history in this contribution we review a wide range of approaches used to extract geochemical information from petroleum inclusions and how these can be used to better constrain petroleum systems these techniques can be grouped into optical spectrographic and thermometric non destructive methods or destructive chemical analyses of bulk samples or individual inclusions typically optical methods documenting the distribution and visual properties of petroleum inclusions are used to provide petrographic context for subsequent specialised geochemical analyses of petroleum inclusions additional non destructive techniques such as raman spectroscopy can then be applied to provide some further insights into the composition of the trapped fluids although the complex nature of petroleum generally requires direct access to the fluid for a more complete understanding of geochemical aspects a variety of destructive techniques have been developed initially to analyse bulk samples released by mechanical crushing and more recently through ablation type techniques that allow the composition of individual inclusions to be characterised screening geochemical techniques that utilise mechanical crushing of bulk samples to analyse petroleum inclusions using mass spectrometry without prior chromatographic separation have become routine analyses other geochemical techniques more geared towards detailed molecular information such as biomarkers utilise chromatographic separation prior to mass spectrometry evaluation of the isotopic composition of petroleum inclusions is also possible for both bulk samples and compound specific analyses the use of lasers to open individual inclusions allows the released contents to be analysed by thermal extraction gas chromatography mass spectrometry gc ms or mass spectrometric mapping of minerals using time of flight secondary ion mass spectrometry tof sims a surface sensitive analytical method that uses ion beams to ablate into minerals the continued evolution of techniques to analyse the incredibly small volume of hydrocarbons trapped within fluid inclusions has progressed to a point where there is little that can be done to evaluate a live oil or gas sample that cannot be achieved for a fluid inclusion sample the full power for tracing petroleum systems is however only realised where there is an effective integration of fluid inclusion data with a more conventional approach to petroleum systems analysis

organic inclusions in salt part 3 oil and gas inclusions in cambrian evaporite deposit from east siberia a contribution to the understanding of nitrogen generation in evaporites abstract halite in cambrian kcl deposits from the southern part of the siberian platform which have been thermally overprinted by dolerite intrusions commonly contains inclusions dominantly composed of co2 and less commonly host inclusions composed of hydrocarbons four types of hydrocarbon inclusions have been identified in samples taken from locations devoid of dolerite intrusions these are 1 monophase gaseous inclusions i e n2 ch4 or n2 ch4 2 aliphatic oil inclusions 3 two phase l1 l2 hydrocarbon brine inclusions and 4 n2 hydrocarbon inclusions the area where the n2 rich inclusions occur is associated with ammonium free k chlorides by comparing different types of k salt environments the origin of the nitrogen could be identified first ammonium ions are produced by deamination of organic matter and stored in k chlorides and thereafter n2 is released from nh4 k minerals by oxidation in zones rich in iron oxides and or by 40k radiolysis

geochemical comparison of oil bearing fluid inclusions and produced oil from the toro sandstone papua new guinea abstract a detailed study was carried out to compare the geochemistry of the crude oil in the lower cretaceous toro sandstone reservoir in the iagifu 7x well with oil trapped in fluid inclusions in this sandstone in the iagifu 7x and p nyang 2x wells in the papuan fold belt the drill stem test dst oils and the oils trapped in fluid inclusions show different source and maturity dependent geochemical parameters biomarkers suggest that the dst oils at iagifu 7x were derived from clay rich mixed marine terrestrial source rocks deposited under oxic conditions probably middle to late jurassic mudstones the fluid inclusion oils were derived from a less terrestrially influenced marine source rock deposited under less oxic conditions the fluid inclusion oils contain 1 2 7 trimethylnaphthalene and oleanane biomarkers indicative of angiosperm input and a cretaceous or younger source rock these oils are more mature calculated reflectance rc 1 02 than the reservoired oil at iagifu 7x rc 0 84 and condensate at p nyang 2x rc 0 84 source and thermal maturity parameters for all three fluid inclusion samples are similar suggesting that they were derived from similar source rock facies furthermore samples with predominantly blue vs white fluorescing oil inclusions have no discernible geochemical maturity difference suggesting that the use of fluorescence colours as a qualitative guide to the maturity of the trapped oil is not valid in this case fluid inclusion oils were trapped prior to charge of the reservoir with oil at the iagifu 7x and gas condensate at the p nyang 2x wells the fluid inclusion oils therefore represent an early oil charge from a deeply buried probably cretaceous source rock which started migrating into the toro sandstone during the miocene at iagifu this early oil was probably diluted by a larger volume of jurassic oil generated at the end of the miocene the absence of fluid inclusions with compositions like the currently reservoired oil is interpreted to be due to oil charging an already oil saturated zone when diagenesis is likely to have been inhibited at the p nyang well the transition from oil as represented by the oil inclusions to gas condensate was most likely caused by gas displacement

analysis of single oil bearing fluid inclusions in mid proterozoic sandstones roper group australia hydrocarbons and organic biomarkers extracted from black shales and other carbonaceous sedimentary rocks are valuable sources of information on the biodiversity and environment of early earth howe