the occurrence of norlupanes and bisnorlupanes in oils of tertiary deltaic basins lupanoid hydrocarbons are known to occur in several petroleum systems and lupane c30 has recently been confirmed to exist in several crude oils in contrast norlupanes c29 and bisnorlupanes c28 are rarely observed in oil all of these compounds are considered to derive from natural products of angiosperms and numerous examples of their functionalized analogs are known the occurrence of c28 and c29 lupanoids in biochemical and geochemical systems is reviewed here and the presence and origin of their hydrocarbon analogs in crude oils are examined in detail although direct biochemical precursors for the lupane of crude oil are evident such precursors for norlupane and bisnorlupane are not obvious nor is it clear if the c28 and c29 analogs are diagenetic descendants from the lupane structure adding additional confusion is the occurrence of these analogs in oils which show numerous indications of post source molecular addition during migration and entrapment making it unclear if they originate from a conventional source rock or from carrier or seal rock despite these uncertainties there is extensive potential some of which has already been realized to use these compounds in oil oil and oil source rock correlations particularly in instances where extensive biodegradation has occurred deconvolution of the time s of introduction of norlupane and bisnorlupane into the fluid as well as various other hydrocarbons including olefins also provides great potential as a tool for mapping the migration history of an oil

geology and petroleum potential of upper cretaceous and tertiary strata beaufort mackenzie area northwest canada 1 upper cretaceous to holocene strata on the beaufort sea continental margin were deposited as a series of northward prograding delta complexes totaling 12 16 km thick the succession contains eleven regionally extensive transgressive regressive sequences that were deposited during four large scale tectonostratigraphic phases each phase terminated by a major tectonic event during the cenomanian to middle maastrichtian sedimentation was limited to relatively thin organic rich muds on an outer shelf to basinal environment from the late maastrichtian to middle eocene deltaic depocenters were located along the southwestern margin of the canadian beaufort sea during the third depositional phase middle eocene to late miocene sedimentation was concentrated in the central canadian beaufort sea depocenters shifted to the eastern beaufort sea during the fourth depositional phase pliocene to early pleistocene the modern mackenzie delta may represent a new phase of deposition considerable volumes of oil and gas have been discovered in tertiary rocks principally in eocene and oligocene delta front strata with lesser volumes in paleocene and miocene strata three families of oils have been recognized in tertiary reservoirs the most important of which appears to have been derived from the eocene richards sequence in general tertiary strata have modest toc total organic carbon values 1 2 and low thermal maturity to drilled depths 4000 4500 m in the more extensively explored central beaufort mackenzie area however thermal and subsidence modeling of tertiary strata suggest that maturity rapidly increases between 5000 and 6000 m

salt karst and tectonics sinkholes development along tension cracks between parallel strike slip faults dead sea jordan this work deals with the tectonic interpretation of an alignment of more than 300 sinkholes stretching along the jordanian coast of the dead sea ghor al haditha area its dimensions are 6 km long with a width of 600 m sinkholes appeared during the last decades as a consequence of the very rapid lowering of the lake level the linear shape was inferred from ground collapse inventories carried out between 1991 and 2008 the lineament is replaced and analyzed in its structural setting at regional and local scales its direction n 24 e is sub parallel to the ones displayed by many focal mechanisms especially the one associated with the earthquake of the 23 april 1979 mb 5 1 n 20 e 5 which is representative of all focal mechanisms calculated on a fault plane compatible with the general direction of the jordan dead sea transform fault system for the east coast of the dead sea area the alignment of sinkholes is constituted by 13 minor linear segments separated by as many empty spaces four minor linear units present an en echelon arrangement from which one can deduce the presence of a local extensional stress field in this context the sinkhole locations provide information of subsurface discontinuities interpreted as hidden fractures in a close future such results could support the work of decision makers and engineers in the projected development of the area copyright 2009 john wiley sons ltd

fault dissolution front relations and the dead sea sinkhole problem abstract there are two conflicting models of sinkhole development along the dead sea ds the first one considers structural control on sinkholes constraining them to tectonic lineaments this hypothesis is based on seismic reflection studies suggesting that sinkholes are the surface manifestations of active neotectonic faults that may serve as conduits for under saturated groundwater enabling its access across aquiclude layers another hypothesis based on results of multidisciplinary geophysical studies considers the salt edge dissolution front as the major site of sinkhole formation this hypothesis associates sinkholes with karstification of the salt edge by deep and shallow undersaturated groundwater our recent seismic reflection and surface wave studies suggest that salt formed along the active neotectonic faults sinkholes form in a narrow strip 60 100 m wide along a paleo shoreline constrained by faults and alluvial fans which determined the edge of the salt layer this scenario reconciles the two major competing frameworks for sinkhole formation

quantitative assessment of in situ salt karstification using shear wave velocity dead sea abstract the dead sea ds coastal areas have been dramatically affected by sinkhole formation since around 1990 such sinkholes along both israeli and jordanian shores are linked to karst cavities that form through slow salt dissolution a quantitative estimate of such in situ salt karstification would be an important indicator of sinkhole hazard one of the indications of salt karstification is its increased hydraulic conductivity caused by the development of dissolution cavities forming conducting channels within the salt layer we measured the hydraulic conductivity k versus shear wave velocity vs of ds salt in situ for estimating the actual salt karstification in areas of sinkhole development these parameters were measured with the magnetic resonance sounding mrs and multichannel analysis of surface waves masw methods respectively understanding of the field relationships was augmented by similar inter relations obtained in the laboratory on samples of ds salt in situ salt velocities vs vary from 750 m s to over 1650 m s while hydraulic conductivity k in the same zones varies between about 10 4 m s to slightly over 10 8 m s both field and laboratory k and vs values fit the exponential function ln k 0 0045 vs 5 416 with a determination coefficient r2 of 0 88 a classification based on vs and k was generated for salt conditions and the corresponding degrees of sinkhole hazard which was verified in the mineral beach sinkhole development area the mapping of sinkhole sites shows that they form within highly conductive zones with k 5 5 10 5 it is suggested that this methodology with some modification can be used for evaluating the conductive properties of karstified rock and associated sinkhole hazards

an investigation of the geometric controls on the morphological evolution of small scale salt terrains cardona spain small scale terrains on salt materials were surveyed with a total station and a series of digital elevation models dems constructed two sets of observations were made eight months apart during which the terrains underwent significant erosion the difference in elevation shown by the dems calculated by subtraction is a measure of surface erosion of the salt terrains the erosion rate was analysed with respect to four terrain parameters calculated in the software high erosion rates and their strong control by terrain slope are demonstrated supporting an earlier study using erosion pins slope profile curvature is also indicated as having some influence the combination of scanning total station and dem software is shown to be an effective tool for investigating rapid geomorphic change at this scale of study

deep basin gas new insights from kinetic modelling and isotopic fractionation in deep formed gas precursors abstract the formation and origin of high maturity gas from tertiary sediments in the mackenzie delta have been studied using programmed temperature closed system pyrolysis mssv different open system devices and numerical models for geological predictions a sample from the type iii taglu sequence was selected as being representative for one of the major hydrocarbon prone deltaic sediments in this area artificial maturation under closed system conditions was carried out at three different heating rates 0 2 0 7 and 5 0 k min the gas composition as well as carbon isotopes of formed methane were analysed using gc fid and gcirms structural characteristics of the residual macromolecules formed during these experiments were studied at different levels of thermal stress immature 360 412 and 470 c under closed system conditions the taglu sequence forms unusually high amounts of gas at extreme levels of thermal stress the recombination of previously formed hydrocarbons with residual kerogen coal through aromatisation polycondensation reactions is the best explanation for these high temperature features a feature previoulsy reported for the heather formation north sea when the neoformed material becomes active and forms gas at high levels of maturity carbon isotopes measured on methane fall to values that are 10 lighter than those from open system gas formation networks a kinetic model for hydrocarbon formation from this neoformed organic matter has been developed this predicts that the initial phase of the neoformation processes shift from post oil formation conditions at laboratory heating rates to peri oil formation conditions when it comes to geological heating rates this may indicate that recombination reactions through aromatisation polycondensation processes partly influence the major phase of petroleum formation in nature and also justifies an enhancement of gas prospectivity at great depths especially in deep basins where source rock maturities exceed 2 5 ro

rock eval tmax suppression documentation and amelioration the rock eval thermal maturation parameter tmax may occasionally be suppressed relative to surrounding rock units this is commonly assumed to result from either a bitumen contribution to the s2 peak or the presence of sulfur rich and hence thermally labile kerogen the phenomenon is frequently coincident with a high natural gamma ray signature and elevated rock eval hydrogen index hi and total organic carbon toc contents determination of thermal maturity of such units relies either on the interpolation of tmax from surrounding units or the direct estimation of the extent of suppression on a given sample the latter may be required if the available samples are restricted to conventional or sidewall core material representative of imited stratigraphic intervals the second white speckled shale part of the cretaceous colorado group in the alberta basin displays tmax suppression over part of its thickness a consistent relationship emerges from calculating a linear regression of tmax as a function of either toc or hi for several wells at different levels of thermal maturity below values of about 453 c late oil window tmax is suppressed by about 1 c for every increase in hi of 50 mg hydrocarbon g toc thus tmax suppression in the second white speckled shale can be corrected by extrapolating all tmax values to a constant hi of 100 to 150 mg hydrocarbon g toc values typical of type iii kerogen

geochemical and petrological evidence for tertiary terrestrial and cretaceous marine potential petroleum source rocks in the western kamchatka coastal margin russia abstract rock eval pyrolysis and microscopic analyses of palaeogene terrestrial strata from the western kamchatka coastal margin russia indicate that good oil prone source rocks are present in both coals and shales hydrogen indices hi of up to 493 mg hc g toc are present in low maturity 0 45 r o vitrinite shale samples from the irgirninvayam river delta region whereas coals with 0 37 0 75 r o and hi of 270 310 mg hc g toc comprise potential oil gas and oil prone source rocks in the kvachincha bay tigel coastal and rassoshina napanskaya river areas the shales and coals with the highest petroleum potential were deposited in a freshwater paleo setting and consist of gelovitrinite cutinite suberinite sporinite resinite and matrix bituminite molecular geochemistry was also used to group genetically related oil samples and to postulate the likely petroleum systems in this area while the preliminary data confirm the origin of two families of oils from the palaeogene deltaic to marginal lacustrine source rocks the chemical composition of oils in two other families suggests the possible presence of marine source rocks in not yet penetrated upper cretaceous paleocene sequences of the basin

the structure of the dead sea basin abstract the dead sea basin is located along the left lateral transform boundary between the arabian and sinai plates its structure and history are known from surface geology drilling seismic reflection and other geophysical data the basin comprises a large pull apart almost 150 km long and mostly 8 10 km wide which is flanked by a few kilometres wide zones of normal faulting the basin formed at about 15 ma or earlier close to the beginning of the transform motion and it reached about half its present length before the end of the miocene a strong negative gravity anomaly records a thick sediment basin fill 5 km under half its length reaching a maximum of 10 km the fill includes a few km of salt ca 6 4 ma which forms several diapirs at any one time large parts of the basin subsided simultaneously but the site of fastest subsidence seems to have shifted northward sedimentation rates reached at least hundreds of metres per million years or more in the miocene and 1 km myr in later periods the basin structure is dominated by longitudinal faults intrabasinal faults which delimit the pull apart and which are the extensions of the major strike slip faults north and south of the basin and normal faults which extend along the basin margins the latter faults express a small component of extension across the basin whereas the pull apart resulted from the much larger lateral motion along the basin in addition transverse faults divide the pull apart into several segments with somewhat different histories the pull apart grew by becoming longer parallel to the transform motion at shallow levels this was probably achieved by normal slip on transverse listric faults while the fill between them was little deformed the crust under the basin was stretched and thinned during basin lengthening which caused its subsidence basin formation was accompanied by uplifting of its flanks by 1 km sparse igneous activity occurred along the basin and its flanks its presence suggests a thermal anomaly in the lower lithosphere beneath the basin and adjacent parts of the transform

salt dissolution and sinkhole formation along the dead sea shore 1 the formation of sinkholes at the dead sea area reflects subsurface cavities formed by salt dissolution this dissolution is related to the recession of the dead sea the groundwater level and the fresh saline water interface along the shore decline at a similar rate to the rate of the dead sea recession and brines that used to occupy layers below this interface are flushed out by freshwater our finite element modeling shows that dissolution of this salt layer is a plausible mechanism to explain the rapid creation of subsurface holes that collapse and form sinkholes the positive feedback between the rate of flow the rate of chemical reaction and the change in permeability accelerates the dissolution processes and might result in reactive infiltration instability which is manifested in fingers of cavities into which fluid is channeled and salt is dissolved the spacing between the sinkholes and the rate of their creation is controlled by several factors including properties of lineaments faults incoming groundwater flux the salinity of the incoming groundwater the rate of dissolution the effective specific surface area the permeability of the salt and clay layers the permeability porosity relation the dispersivity and the thickness of the layers we show that the creation of sinkholes occurs only under specific conditions these conditions must cause an unstable dissolution front which then causes formation of cavities and eventually sinkholes the simulations which utilized the best estimated parameters of the studied area yield results that are similar to those exhibited in the field

organic geochemistry and organic petrology of a potential source rock of early eocene age in the beaufort mackenzie basin abstract the biological marker compounds 17 h and 17 h 23 28 bisnorlupane have been identified in a coaly interval at about 3300 3320 m depth within the lower taglu sequence early eocene in the immiugak a 06 well in the beaufort mackenzie basin these biomarkers were previously only known to occur in the lower part of the richards formation and were thus used to infer that the richards was the source for most of the tertiary oils and condensates in the basin the discovery of bisnorlupanes in older much more organic rich rocks indicates that the previous oil source rock correlations may not have been correct and that the coals in the lower taglu sequence are likely the dominant effective source rock especially for the paleocene and early eocene reservoirs in the southern part of the mackenzie delta petrographic and rock eval analyses indicate that the lower taglu sequence coaly section should be mainly a source for gas but with some potential to expel liquids the level of thermal maturity inferred from rock eval tmax 432 438 c equivalent to about 0 65 0 75 ro vitrinite is slightly higher than that inferred from the measured reflectance fluorescence and foraminiferal colouration index which all indicate that the maturity at 3300 m is about 0 60 0 65 ro vitrinite equivalent at the gulf et al immiugak a 06 well site

the petroleum geochemistry of canadian beaufort tertiary non marine oils abstract molecular isotopic and elemental data for a set of 28 paleogene and 3 cretaceous oils from the mackenzie delta and offshore canadian beaufort sea have been evaluated the depositional environment and organic matter characteristics of the source units for these oils have been predicted the paleogene oils of the canadian beaufort are molecularly distinctive and clearly contain a major land plant component oleanane and the 17 h and 17 h 24 28 bisnorlupanes are present as well as the following compound types 24 norlupanes and possibly higher homologues de a lupane noroleanenes norursene dehydroabietane 28 30 bisnorhopanes several molecular and isotopic characteristics are useful in assessing and ordering the extent of biodegradation and thermal maturation of these oils the cretaceous oils are separately sourced from the paleogene oils the latter oils comprise two distinct land plant derived genetic families distinguished by the presence absence of 24 28 bisnorlupanes 24 norursene 24 norlupane and 24 noroleanenes the kugmallit richards family contains each of these compound types and is considered to originate from the eocene richards formation in contrast lupanoids and noroleanenes are absent in oils of the reindeer moose channel family the occurrence of 28 30 bisnorhopane and or oleanane in these oils suggests a paleocene origin although these source rock predictions are supported by the available data they must be considered speculative until detailed molecular isotopic and elemental compositional data are available regionally for potential source rocks of the eocene and paleocene source units in the canadian beaufort

fluorescence alteration and the suppression of vitrinite reflectance abstract vitrinite reflectance is a highly important thermal maturity indicator in petroleum exploration but there are a number of problems in its successful application which are basically the consequence of it being a single parameter technique fluorescence alteration of macerals which can be conveniently measured with the laser raman microprobe is a multi parameter technique which can be used to overcome some of these limitations on a fluorescence alteration diagram most vitrinite plots on or close to a line which may be called the normal vitrinite line fluorescence alteration data for a suite of randomly selected macerals from coal or dispersed organic matter plot along a curve which cuts the normal vitrinite line at the equivalent vitrinite reflectance of the sample as determined by calibration againsta suite of reference coals the technique posseses a high degree of objectivity and can be employed to determine the equivalent vitrinite reflectance of samples in which the vitrinite is difficult to identify or even absent perhydrous vitrinites with suppressed vitrinite reflectance are readily recognized as they plot in a field laterally displaced with respect to the normal vitrinite line the method is exemplified by a study of coals from the greta and pelton seams sydney basin which provides a classic example of vitrinite reflectance suppression and is further illustrated by a study of the dampier 1 well from the north west shelf of australia which contains both perhydrous macerals and dispersed organic matter in which vitrinite is difficult to identify

old marine seismic and new satellite radar data petroleum exploration of north west labrador sea canada abstract this paper presents some new concepts in the petroleum systems of the northern labrador and southern baffin island offshore region of eastern canada the focus of this work is the region of the hekja o 71 gas discovery of 1979 by aquitaine one of only five wells drilled between 1976 and 1980 within an area covering some 166 000 square kilometers within the saglek basin this study emerged from a broad scale re examination of the petroleum potential of this area from the crust up using regional reflection refraction and potential field data an opportunity to use sar synthetic aperture radar data from the radarsat 1 earth observation satellite was taken to incorporate alternative data sources to support this exploratory review and resource assessment examination of the final map of interpreted slick like features on the sea surface revealed a close correlation of some of these occurrences to several bathymetric features which have underlying seismic signatures similar to previously identified gas hydrate pipes or chimney anomalies as seen in data from offshore nova scotia and in the irish sea globally many active marine hydrocarbon seeps appear on the seafloor as pockmarks in this case no seafloor depressions were seen on conventional multi channel 2 d seismic data associated with active seepage instead very distinct mound like structures are seen associated with seeps at two locations east of hudson strait the presence of significant cold water coral in close proximity to the active seepage sites may show a link between seafloor petroleum seepage and coral reef development similar to that observed offshore norway close examination of the near surface seismic character led to the interpretation of what was originally seen as seismic noise in vintage data as likely being fluid escape chimneys or gas pipes along the eastern edge of the hekja structural complex where favourable hydrocarbon trapping conditions are present no active seeps were seen there this may be due to other factors such as the nature of the fluids that are escaping or the possibility of self sealing activity by biological agents such as bacterial matting with associated carbonate hard ground formation one seep anomaly was noted relatively close to the major basaltic eruptive complex near the gjoa g 37 well this may be due to the presence of volcaniclastic hosted hydrocarbons similar in style to those recently discovered at the rosebank field in paleocene volcanics in the faroe shetland basin the occurrence of an active seep in a volcanically dominated terrain raises the potential for a radical shift in accepted types of petroleum leads and where they may occur the presence of apparent oil seepage versus the past history of finding only gas prone accumulations is a strong indicator that a second oil prone petroleum system exists in the saglek basin the signs of active petroleum systems as shown by oil seep anomalies with confirming seismic evidence of discrete sea floor structures in close proximity makes a compelling argument for re examining these areas with an eye towards stratigraphic instead of structural plays

sinkhole swarms along the dead sea coast reflection of disturbance of lake and adjacent groundwater systems more than a thousand sinkholes have developed along the western coast of the dead sea since the early 1980s more than 75 of them since 1997 all occurring within a narrow strip 60 km long and 1 km wide this highly dynamic sinkhole development has accelerated in recent years to a rate of 150 200 sinkholes per year the sinkholes cluster mostly over specific sites up to 1000 m long and 200 m wide which spread parallel to the general direction of the fault system associated with the dead sea transform research employing borehole and geophysical tools reveals that the sinkhole formation results from the dissolution of an 10 000 yr old salt layer buried at a depth of 20 70 m below the surface the salt dissolution by groundwater is evidenced by direct observations in test boreholes these observations include large cavities within the salt layer and groundwater within the confined subaquifer beneath the salt layer that is undersaturated with respect to halite moreover the groundwater brine within the salt layer exhibits geochemical evidence for actual salt dissolution na cl 0 5 0 6 compared to na cl 0 25 in the dead sea brine the groundwater heads below the salt layer have the potential for upward cross layer flow and the water is actually invading the salt layer apparently along cracks and active faults the abrupt appearance of the sinkholes and their accelerated expansion thereafter reflects a change in the groundwater regime around the shrinking lake and the extreme solubility of halite in water the eastward retreat of the shoreline and the declining sea level cause an eastward migration of the fresh saline water interface as a result the salt layer which originally was saturated with dead sea water over its entire spread is gradually being invaded by fresh groundwater at its western boundary which mixes and displaces the original dead sea brine accordingly the location of the western boundary of the salt layer which dates back to the shrinkage of the former lake lisan and its transition to the current dead sea constrains the sinkhole distribution to a narrow strip along the dead sea coast the entire phenomenon can be described as a hydrological chain reaction it starts by intensive extraction of fresh water upstream of the dead sea continues with the eastward retreat of the lake shoreline which in turn modifies the groundwater regime finally triggering the formation of sinkholes

alkane and pah biomarkers as tracers of terrigenous organic carbon in arctic ocean sediments abstract we present the first sedimentary biomarker study encompassing the entire arctic ocean a large data set of organic markers for terrigenous petroleum and combustion inputs alkanes hopanes and steranes parent and alkyl polycyclic aromatic hydrocarbons pahs is examined for patterns in space and time using principal components analysis pca and partial least squares pls biomarker patterns reveal the central arctic ocean basin sediments to be compositionally distinct from those of the mackenzie river beaufort sea and barents sea but similar to those of the laptev sea pah distributions reflected in pah ratios and pca projections demonstrate that arctic ocean sediment is dominated by natural inputs to the extent that anthropogenic combustion pahs are not significant we find only modest changes between the glacial and post glacial sediments for atmospherically transported hydrocarbon biomarkers while particle associated biomarkers were captured strongly at basin edges during the glacial period and much more evenly transported across basins during the post glacial period the orders of magnitude decreases in particle associated petrogenic alkanes and pahs in central basins during glacial times coupled with the uniformity of most petrogenic biomarker parameters for most basin and shelf locations reflect a massive reduction in ice transport that makes the margins the most likely source of petrogenic material for the pleistocene holocene central arctic basins the proximity of large coal deposits of various maturity levels along the lena river the overlap in pah and biomarker composition of the laptev sea and surficial sediments from the central arctic ocean and the location of the laptev sea at the origin of the main transpolar drift all point to eroded coals from the lena river laptev sea as the likely source of petrogenic hydrocarbons to the central arctic ocean the ubiquitous presence of allochthonous coal in arctic ocean surface sediments provides a major constraint on the use of petrogenic biomarkers to infer the presence of subsurface petroleum reserves

detection of subsurface brines freshwater bodies and the interface configuration in between by the time domain electromagnetic method in the dead sea rift israel high radon fluxes in the seismically active dead sea rift seem to be affected by the hydrological system and the different salinities of groundwater bodies involved the time domain electromagnetic tdem method was employed to delineate those different bodies and the configuration of the interfaces between them the present hydrological system and the related brines and interfaces are controlled by the dead sea base level presently at 408 m below msl tdem measurements detect low resistivity 1 ohm m units representing brines and the interface between them as well as the overlying fresher water bodies in addition high resistivity freshwater units are also detected underlying the brines related herein to a multiple hydrological system low resistivity brines detected above the present base level are interpreted herein as yet unflushed ones which correspond to a former higher base level higher sequences below historical sixteenth century base levels are already devoid of brines which gives an indication as to the rate of flushing

locating water filled karst caverns and estimating their volume using magnetic resonance soundings magnetic resonance sounding mrs is a geophysical technique developed for groundwater exploration this technique can be used for investigating karst aquifers generally the study ofakarstrequiresa3dfieldsetupandcorrespondingmultichannel data acquisition instruments now only single channel mrs equipment is available i e the time needed for a 3d mrs field survey is multiplied by a factor of four or five where karst caverns are natural hazards as in the dead sea coastal area at nahal hever israel even an approximate localization of potentially dangerous zones and a corresponding estimation of the hazard dimensions are useful we studied numerically the accuracy of mrs estimations of the volume of different 3d targets around nahalhever shiftinga3dtargetinsidethemrsloopandcalculating the volume estimation errors for each target position the calculations covered targets of different sizes the size and position of a target being unknown factors in a field survey the numerical data were considered as random values to be analyzed statistically using a 1d approximation of the mrs solution and assuming a 100 100 m 2 mrs loop the volume of a 3d target under nahal hever conditions is estimated within a 75 error when the target is smaller than the mrs loop and within a 50 error when the target size is about the same as the mrs loop the lower threshold of karst cavity detection with mrs is about 6500 m3 for such estimation only one sounding is

carbon isotope stratigraphy and the problem of a pre tommotian stage in siberia carbon isotopic oscillations are useful to elucidate the stratigraphy and biogeochemical events around the precambrian cambrian transition new isotopic data from the manykaj and emyaksin formations of the eastern anabar uplift siberia help to correlate the lower cambrian and neoproterozoic cambrian transitional beds across the siberian platform the similarity of trends and amplitudes of the carbon isotopic curves together with biostratigraphic and sequence stratigraphic markers from the anabar uplift provide a precise correlation with the southern part of the siberian platform diagenesis of argillaceous limestones of the emyaksin formation has appar ently not affected the primary isotopic variations the resulting curve is nearly identical in sections about 100 km apart in the tommotian atdabanian portion of the formation relatively frequent and pronounced isotopic oscillations in the lower beds of the emyaksin formation fit between features i and ii of the southern siberian isotopic reference scale but are undetected therein owing to the deposi tional hiatus at the base of the tommotian stage in its type section this confirms the transgressive onlap from the north suggested by previous studies and makes the appearance of the cambrian skele tal fossils on the siberian platform less abrupt the hiatus in the south appears to embrace at least two biostratigraphic zones as recognized in the north the case is strengthened for a pre tommotian cambrian stage in siberia the biostratigraphic framework for which has been elaborated earlier

pre existing caverns in salt formations could be the major cause of sinkhole hazards along the coast of the dead sea since 1990 hundreds of sinkholes have appeared along the coast of the dead sea in the literature the rapid development of sinkholes is explained as a result of a drop in the level of the dead sea this model assumes very fast dissolution of large volumes of salt and the creation of new caverns that cause sinkholes in 10 to 20 years however the results of our geophysical study do not confirm the fast dissolution assumption to explain the available field observations we propose the following model 1 slow dissolution of salt much longer than 20 years with the creation of caverns without development of sinkholes 2 sinkhole development is triggered by the lowering of the groundwater level because the rocks overlying the salt formation become unsaturated 3 the time of sinkhole appearance is controlled by the mechanical properties of the rocks that overlie pre existing caverns

geophysical prediction and following development sinkholes in two dead sea areas israel and jordan geophysical methods seismic refraction srfr electrical resistivity tomography ert and microgravity were applied to the dead sea ds sinkhole problem in the ein gedi area at the earlier stage of the sinkhole development 1998 2002 they allowed determining the sinkhole formation mechanism and localizing the sinkhole hazardous zones the srfr method permitted to delineate the underground edge of a salt layer at the depth of 50 m the salt edge was shaped like the sinkhole line on the surface it was concluded that the sinkhole development is linked to the salt edge geoelectrical quasi 3d mapping based on the ert technique detected large resistivity anomalies with 250 300 m2 diameter and 25 35 m deep the ein gedi area has been also mapped by the use of microgravity method the residual bouguer gravity anomaly map shows negative anomalies arranged along the edge of the salt layer those gravity anomalies overall are very similar in plan to the resistivity distribution in this area the results of forward modeling indicate that both high resistivity and residual gravity anomalies are associated with a subsurface decompaction of the soil mass and deep cavity at the sinkhole site following monitoring of the sinkhole development carried out by the geological survey of israel confirmed our suggestions the drilling of numerous boreholes verified the location of the salt edge geographical information system gis database testifies that during 2003 2009 new sinkholes are continuing to develop along the salt edge within a narrow 50 100 m wide strip oriented approximately in north south direction slightly parallel to the shoreline no promotion in west east direction perpendicularly to the ds shoreline was observed in israel collapse of sinkholes and their clustering have been occurred within the area of high resistivity anomaly and negative residual gravity anomaly similar studies carried out at the ghor al haditha area jordan have shown that sinkholes there are also arranged along the winding line conforming to the salt edge in this area sinkholes are slowly moved to the dead sea direction results of geophysical studies in numerous ds sites indicate similar sinkhole development it allowed generating of the sinkhole formation model based on ancient 10 000 11 000 year old salt belt girding the dead sea along its shores

immature oil and condensate modification of hydrocarbon generation model for terrestrial organic matter petroleum has been found in canadian frontier basins in reservoirs which have undergone low levels of thermal alteration vitrinite reflectance 0 6 ro paraffin indices stable carbon and hydrogen isotope contents pristane to nc17 ratios and diterpenoid biologic markers have been used to assess the level of maturity of the hydrocarbons in the reservoir independently of the level of maturity of the reservoir itself and of the surrounding shale units in the tertiary of the beaufort mackenzie basin naphthenic oils and condensates have been generated from terrestrially derived organic matter in source rocks juxtaposed with the reservoir at reflectance levels of 0 4 to 0 6 ro however condensates discovered in reservoirs which are th rmally immature on the labrador shelf have undergone extensive vertical migration and can be classed as conventional mature to overmature condensates hydrocarbons discovered in the lower cretaceous of the beaufort mackenzie basin and also those of the scotian shelf are more or less in place in that they are at a level of thermal alteration about equivalent to that of the reservoirs in which they are trapped the source for the early oils and condensates is considered to be resinite occurring dispersed in coal fragments the proportion of resinite liptinite and vitrinite in the organic matter of terrestrial source rocks strongly controls both the level of thermal alteration necessary for the section to function as an effective source rock and the ultimate product gas oil or condensate which will be generated

late paleocene middle eocene hydrocarbon source rock potential in the arctic beaufort mackenzie basin abstract the natsek e 56 oil and gas exploration well from the arctic beaufort mackenzie basin bmb was selected for a multi disciplinary study because its strata contain a record of two major eocene climate events that affected source rock deposition the paleocene eocene thermal maximum petm at 55 5 ma and the early mid eocene azolla event at 49 ma rock eval data from natsek e 56 indicates a previously overlooked potentially economically significant interval that occurs just below petm strata the pre petm unit is an organic rich 30 toc coaly shale deposit with good hydrocarbon source rock potential and marginal thermal maturity this carbonaceous deposit is characterized by a relatively elevated hydrogen index hi 149 mg hc toc s2 38 mg hc g rock which suggests increased input of liptinitic rich material similar to the sapropelic boghead coal formed in lacustrine environments in the vicinity of the modern beaufort mackenzie delta plain in recent years source rock predictions for the eocene arctic were postulated from cores on the lomonosov ridge focusing on organic matter om produced during the azolla event om associated with azolla also occurs in the natsek e 56 toc ranges from 1 to 14 but reworked terrestrial matter is a dominant component the pre petm organic rich interval of natsek e 56 was not recorded at the lomonosov ridge while in natsek e 56 the interval consists of toc values double that recorded at any point in the lomonosov ridge wells the occurrence of multiple potential source rocks from the unique depositional environments in the bmb indicates oil and gas potential in late paleocene middle eocene strata of the beaufort mackenzie region

the paleogene vegetation and petroleum system in the tropics a biomarker approach abstract the present study investigates the biomarker signatures of sediments and crude oils to infer the paleovegetation from the two petroleum systems of assam basin eastern india they are classified as the paleocene middle eocene and the middle eocene oligocene petroleum systems the sediments are oil and gas prone with an early catagenetic stage of thermal evolution here we report tricyclic diterpanes such as rimuane pimarane rosane and isopimarane along with tetracyclic diterpanes ent beyerane phyllocladane kaurane from paleocene eocene coal bearing sediments and crude oils these diterpane biomarkers attest dominant contribution from conifers possibly from podocarpaceae and araucariaceae however diterpanes are not detected in oligocene sediments and oils crude oils from both paleocene eocene and oligocene reservoirs and organic rich sediments contain angiosperm biomarkers such oleanane and related triterpanes along with bicadinane a biomarker specific for the dipterocarpaceae family of angiosperms the equatorial position of india during early paleogene along with the presence of angiosperm signatures including dipterocarpaceae and gymnosperms reflect the emergence of tropical rainforest elements in eastern india absence of diterpenoids in oligocene samples and difference in angiosperm parameters from paleocene eocene samples suggests a change in source vegetation and organofacies

oleanane or lupane reappraisal of the presence of oleanane in cretaceous tertiary oils and sediments nonpolar gc columns are normally used for gc ms analysis of saturate fractions from crude oils under these conditions lupane coelutes with oleananes and some minor c30 compounds of non terrigenous origin having lupane like mass spectra because any peak eluting fractionally earlier than 17 21 h hopane in the m z 191 mass chromatogram is routinely assigned to oleanane the presence of lupane may sometimes have been overlooked lupane and oleananes are easily separated using reverse phase hplc triterpane concentrates from 10 crude oils known to contain oleananes were hplc separated lupane was unambiguously identified in six of the oils by full scan gc ms analysis of fractions having the hplc retention time of authentic lupane gc separation of lupane and oleananes is possible using polar gc columns having a polyethylene glycol stationary phase organic geochemistry 23 1995 21 allowing estimation of the lupane lupane oleanane ratio high ratios were measured in the marraat oil west greenland 0 8 and the amauligak oil from the beaufort mackenzie delta 0 26 the results suggest that lupane may be more frequently occurring than previously thought and that this compound is preferably associated with high latitude samples high concentrations of 28 nor and 24 28 bisnortriterpanes oleananes lupanes and taraxastanes were detected in the marraat oil

black shale formation in the late paleocene early eocene arctic ocean and paleoenvironmental conditions new results from a detailed organic petrological study abstract the study of particulate organic matter om in arctic ocean sediments from the late cretaceous to the eocene iodp expedition 302 has revealed detailed information about the aquatic marine om fluxes biological sources preservation and export of terrestrial material here we present detailed data from maceral analysis vitrinite reflectance measurements and organic geochemistry during the campanian paleocene fluxes of land derived om are indicated by reworked and oxidized macerals vitrinite inertinite and terrigenous liptinite cutinite sporinite in the early eocene drastic environmental changes are indicated by peaks in aquatic om up to 40 45 lamalginite telalginite liptodetrinite dinoflagellate cysts and amorphous om up to 50 bituminite these events of increased aquatic om flux similar to conditions favoring black shale deposition correlate with the global 13c events paleocene eocene thermal maximum petm and elmo event freshwater discharge and proximity of the source area are documented by freshwater algae material pediastrum botryococcus and immature land plant material corphuminite textinite we consider that erosion of coal bearing sediments during transgression time lead to humic acids release as a source for bituminite deposited in the early eocene black shales

kinematic inversion of first arrivals of refracted waves a combined approach the inversion of first arrival times of refracted waves in media with laterally varying parameters can be performed using the refraction tomography technique tomographic inversion implemented as a linearized constrained least squares iterative scheme requires some a priori information on either refractor depth or velocity above the refractor however such information may be unavailable on the other hand in many cases a reasonable estimate of the average velocity distribution above the refractor can be obtained by a nontomographic technique such as the generalized reciprocal method grm i propose a combined approach to the inversion problem that uses the advantages of both the refraction tomography and grm techniques and which does not require additional information not contained in first arrival times the approach is based upon two assumptions which prove to be true in most situations the first is that a reasonable local estimate of refractor velocity can be obtained by tomographic inversion independently of other model parameters and the second is that the derivative of the velocity analysis function as defined by the grm gives a good local approximation of the refractor slowness the proposed combined inversion scheme can be described as a three step procedure in the first step the laterally varying refractor velocity is estimated by tomographic inversion in the second step local estimation of laterally varying average velocity above the refractor is performed by the grm on the basis of the previously estimated refractor velocity in the third step the estimated values of the average velocity are used as the corresponding constrained initial parameters for tomographic inversion

unusual biological marker geochemistry of oils and possible source rocks offshore beaufort mackenzie delta canada abstract tertiary oils and source rocks from the offshore beaufort mackenzie delta have been examined for their biological marker content the triterpane and sterane distributions suggest a predominant land plant contribution to the oils the oils range in maturity from extremely immature to moderately mature 18 h oleanne is a major triterpane of the oils together with probable bisnorlupanes and an excellent correlation is observed in the concentration of these components in individual oils an excellent correlation is also observed between the concentration of bisnorlupanes and oil maturity based on sterna and triterpane maturation parameters suggesting that the decrease in relative concentration of these components with increasing maturity is a result of progressive dilution by hydrocarbons generated by the cracking of kerogen only one formation in cores taken from the delta has been found to contain bisnorlupanes and were present they are the dominant hydrocarbons of the branched cyclic fraction

hydrocarbon flow modeling in complex structures mackenzie basin canada the mackenzie basin in northwest arctic canada has many characteristics of a typical terrestrial gas rich sedimentary basin but the origins of this important hydrocarbon province are still not well known the three dimensional basin modeling approach employed here illustrates not only improved capabilities but also potential pitfalls in reproducing flow in complex stratal and structural basin architectures of present day models listric fault structures especially are still inadequately reproduced in most migration models by integrating individual styles of deformation and introducing a sequence stratigraphic approach to reproduce the stratal architecture we are able to identify temporal and spatial relationships between sources and reservoirs based on these considerations three genetic groups of oils in the basin are proposed a first group mainly related to a paleocene source rock a second group related almost exclusively to an early mature source in the eocene taglu formation and a third group related to the upper cretaceous smoking hills and boundary creek formations in contrast to oil accumulations gas accumulations resulted mainly from a filling event in the late miocene which is interpreted to be related to a decrease in pressure during a late miocene uplift and erosional event the mackenzie basin is therefore an excellent example to show that the gas proneness of a mature petroleum system especially if the organic matter is predominantly of terrestrial origin is mainly a function of expulsion efficiency and timing and thus is directly linked to the structural history of the basin

use of gpr method for prediction of sinkholes formation along the dead sea shores israel abstract it seems the highly saline conditions of the dead sea ds coast line are not favorable for the use of ground penetrating radar gpr method for detection of underground caverns before sinkhole formation short time prediction the location of the formed caverns within the salt layer significantly more than the penetration depth of the electromagnetic waves combined with the saline ds brine groundwater covering the salt layer from above characterized by low electrical resistivity makes the application of electromagnetic waves ew impossible however our experience has shown that gpr technique in its 2d and 3d modifications can be a very efficient tool to predict sinkhole susceptibility case histories of gpr studies in the mineral beach and nahal david sites are presented the gpr study has shown that the method is effective in both urban sites and at most of sites of human activities of the dead sea coast dwellings routes agricultural areas etc but it fails in areas composed of saline mud in the subsurface some areas lower than 400 m elevation the fan areas are composed of sandy gravel sediments and the penetrating depth of the electromagnetic waves varies but is usually limited to the first meters up to 8 10 m maximum to 13 15 m but in any case not deeper than the water table depending on the dielectric constant which as a rule is 4 25 in areas covered by dead sea mud penetration depth is limited to the first meter due to the low electrical resistivity of the sediments models of sinkhole formation and principles of cavity detection in the ds area are discussed to understand the fundamentals of gpr use for the prediction of sinkhole susceptibility

identification prediction and mitigation of sinkhole hazards in evaporite karst areas sinkholes usually have a higher probability of occurrence and a greater genetic diversity in evaporite terrains than in carbonate karst areas this is because evaporites have a higher solubility and commonly a lower mechanical strength subsidence damage resulting from evaporite dissolution generates substantial losses throughout the world but the causes are only well understood in a few areas to deal with these hazards a phased approach is needed for sinkhole identification investigation prediction and mitigation identification techniques include field surveys and geomorphological mapping combined with accounts from local people and historical sources detailed sinkhole maps can be constructed from sequential historical maps recent topographical maps and digital elevation models dems complemented with building damage surveying remote sensing and high resolution geodetic surveys on a more detailed level information from exposed paleosubsidence features paleokarst speleological explorations geophysical investigations trenching dating techniques and boreholes may help in investigating dissolution and subsidence features information on the hydrogeological pathways including caves springs and swallow holes are particularly important especially when corroborated by tracer tests these diverse data sources make a valuable database the karst inventory from this dataset sinkhole susceptibility zonations relative probability may be produced based on the spatial distribution of the features and good knowledge of the local geology sinkhole distribution can be investigated by spatial distribution analysis techniques including studies of preferential elongation alignment and nearest neighbor analysis more objective susceptibility models may be obtained by analyzing the statistical relationships between the known sinkholes and the conditioning factors chronological information on sinkhole formation is required to estimate the probability of occurrence of sinkholes number of sinkholes km2 year such spatial and temporal predictions frequently derived from limited records and based on the assumption that past sinkhole activity may be extrapolated to the future are non corroborated hypotheses validation methods allow us to assess the predictive capability of the susceptibility maps and to transform them into probability maps avoiding the most hazardous areas by preventive planning is the safest strategy for development in sinkhole prone areas corrective measures could be applied to reduce the dissolution activity and subsidence processes a more practical solution for safe development is to reduce the vulnerability of the structures by using subsidence proof designs

limitations of use of organic petrographic techniques for identification of petroleum source rocks organic petrographic and organic geochemical studies have been conducted on 58 sediment samples of differing ages and depositional environments in this study interpretations of petroleum source rock potential based on data from transmitted light microscopy show a poor correlation with those derived from chemical data this lack of correlation arises from the failure to distinguish consistently between hydrogen poor and hydrogen rich amorphous organic matter and inability to detect hydrogen rich components exinite and resinite in coal fragments interpretations based on data from reflected light microscopy show a better correlation with those derived from chemical studies but difficulties still remain these difficulties arise from inability except on the basis of luorescence intensity to distinguish hydrogen rich from hydrogen poor organic matter in a finely dispersed state

diterpenoid hydrocarbons in sediments from an offshore labrador well abstract aliphatic hydrocarbon fractions isolated from sediments r 0 0 4 of eocene palaeocene age taken between 2860 and 3055 m in an offshore labrador well were shown to be dominated by a number of compounds with kovats retention indices in the range 1875 1975 analyses of these hydrocarbons by gas chromatography and computerized gas chromatography mass spectrometry suggested that they were tricyclic diterpenoids interpretation of the mass spectra allowed structures to be assigned to some of the compounds and to be proposed for others they appear to belong to the primarane abietane and kaurane classes of hydrocarbons the diterpanes have been used to detect cavings in the deeper sediments between 3055 and 3270 m these compounds are either absent or trace components only of the dst 1 condensate 3212 3256 m or oil impregnating a sandstone core 3250 m and are only abundant in the cuttings from the same depth interval this occurrence of diterpanes in cuttings from the reservoir interval is due mostly to cavings resin like materials from which diterpanes are derived have not contributed significantly to the genesis of the condensate

glacial to postglacial transformation of organic input pathways in arctic ocean basins 1 the arctic ocean is undergoing rapid loss in ice cover with yet unknown consequences for the cycling of organic material here we examine persistent terrigenous land based alkane and polycyclic aromatic hydrocarbons with vascular plant combustion and petrogenic sources in seven cores collected from all major basins of the arctic ocean for insight as to how organic cycling at the last glacial maximum compares to the present day we find only modest changes between the glacial and postglacial sediments for atmospherically transported hydrocarbon biomarkers demonstrating that glacial sea ice was not a barrier to atmospheric inputs in stark contrast particle associated biomarkers were captured strongly at basin edges during the glacial period and much more evenly transported across basins during the postglacial period evidently the capture of organic matter shifted from the slopes to the shelves as the latter flooded during the holocene and the transpolar drift and beaufort gyre evolved from minor carriers of plant detritus from the glacial ocean margins to major modern transporters of shelf sediment to the basins this suggests that changes in organic transport currently accompanying the loss of sea ice are likely to be very different from those that occurred at the end of the last glacial period

collapse sinkholes and radar interferometry reveal neotectonics concealed within the dead sea basin 1 the dead sea ds pull apart basin is one of the more seismically active segments of the ds transform plate boundary in the last decade hundreds of collapse sinkholes have been formed along the ds coastlines in israel and jordan causing severe damage to the regional infrastructure the formation of these sinkholes is attributed to the dissolution of a buried salt layer by fresh groundwater due to the drop of the ds and the associated groundwater levels here we show that the sinkhole distribution combined with gradual land subsidence measured by radar interferometry insar track young fault systems suspected as active concealed within the fill of the ds rift this notion is supported by 1 sinkholes clustering along discrete lineaments with a striking trend similarity to that of the exposed rift margin faults 2 prominent discontinuities in seismic reflection profiles offsetting young sediments several kyrs old below sinkhole lines and 3 straight boundaries of gradual subsidence features that coincide with or parallel sinkhole lines combined the sinkhole lineaments and the insar measurements reveal a zigzag pattern of buried faults within the ds rift fill

a new lower cambrian shelly fossil biostratigraphy for south australia abstract definition of early cambrian chronostratigraphic boundaries is problematic with many subdivisions still awaiting ratification integrated multi proxy data from well resolved regional scale schemes are ultimately the key to resolving broader issues of global correlation within the cambrian in australia early cambrian biostratigraphy has been based predominantly on trilobites phosphatic shelly fauna have great potential as biostratigraphic tools especially in pre trilobitic strata because they are widespread and readily preserved but they have remained underutilised here we demonstrate their value in a new biostratigraphic scheme for the early cambrian of south australia using a diverse shelly fauna including tommotiids brachiopods molluscs and bradoriids biostratigraphic data are derived from ten measured stratigraphic sections across the arrowie basin targeting hawker group carbonates including the wilkawillina wirrapowie and ajax limestones and the mernmerna formation the stratigraphic ranges of shelly fossils are predictable and repeatable across the arrowie basin allowing three discrete shelly biozones to be identified spanning terreneuvian stage 2 to series 2 stages 3 4 the kulparina rostrata zone new and part of the overlying micrina etheridgei zone new are pre trilobitic predominantly terreneuvian the cambrian series 2 stage 3 dailyatia odyssei zone new features a very diverse shelly fauna and will be described in detail in a separate publication these zones provide robust means to correlate terreneuvian series 2 successions in neighbouring coeval basins in australia particularly the stansbury basin wider correlation is possible throughout east gondwana and especially with south china

atmospheric methane from organic carbon mobilization in sedimentary basins the sleeping giant abstract the mass of organic carbon in sedimentary basins amounts to a staggering 1016 t dwarfing the mass contained in coal oil gas and all living systems by ten thousand fold the evolution of this giant mass during subsidence and uplift via chemical physical and biological processes not only controls fossil energy resource occurrence worldwide but also has the capacity for driving global climate only a tiny change in the degree of leakage particularly if focused through the hydrate cycle can result in globally significant greenhouse gas emissions to date neither climate models nor atmospheric co2 budget estimates have quantitatively included methane from thermal or microbial cracking of sedimentary organic matter deep in sedimentary basins recent estimates of average low latitude eocene surface temperatures beyond 30 c require extreme levels of atmospheric co2 methane degassing from sedimentary basins may be a mechanism to explain increases of atmospheric co2 to values as much as 20 times higher than pre industrial values increased natural gas emission could have been set in motion either by global tectonic processes such as pulses of activity in the global alpine fold belt leading to increased basin subsidence and maturation rates in the prolific jurassic and cretaceous organic rich sediments or by increased magmatic activity such as observed in the northern atlantic around the paleocene eocene boundary increased natural gas emission would have led to global warming that was accentuated by long lasting positive feedback effects through temperature transfer from the surface into sedimentary basins massive gas hydrate dissociation may have been an additional positive feedback factor during hyperthermals superimposed on long term warming such as the paleocene eocene thermal maximum petm as geologic sources may have contributed over one third of global atmospheric methane in pre industrial time variability in methane flux from sedimentary basins may have driven global climate not only at time scales of millions of years but also over geologically short periods of time earth system models linking atmospheric ocean and earth surface processes at different timescales with the sedimentary organic carbon cycle are the tools that need to be developed in order to investigate the role of methane from sedimentary basins in earth s climate

petrography and geochemistry of dispersed organic matter in the oligocene source rocks of the central western part of the getic depression romania abstract the aims of this study include the evaluation and interpretation of oligocene source rocks from the central western part of the getic depression romania and the identification of their maturation and their hydrocarbon potential 24 argillite samples belonging to the source rocks were studied using organic petrography and geochemistry methods including rock eval pyrolysis and the following sets of results were obtained maceral diversity values of vitrinite reflectance thermal alteration index and organic geochemical values the oligocene disperse organic matter contains both humic and terrestrial organic matter as well as sapropelic marine algal matter represented by telalginite and lamalginite several anoxic deep marine water intervals were recorded in the getic depression the samples are immature with tmax values ranging between 415 c and 434 5 c and random vitrinite reflectance of 0 32 and 0 53 the samples yield a total organic content between 0 55 and 5 71 with a hydrogen index between 9 and 379 mg g showing two types of kerogen a mixed type ii iii kerogen indicating a generative potential for hydrocarbon and gas and b type iii kerogen indicating a gas generative potential

hydrocarbon migration detected by regional temperature field variations beaufort mackenzie basin canada the regional beaufort mackenzie basin temperature field is characterized using data collected from drill stem tests and bottom hole temperature logs we recognize two thermal anomalies each of which is associated with a specific geological setting elevated temperatures are observed in 1 the western beaufort sea where post eocene erosion removed cenozoic strata and folding is common in a contractional tectonic regime and 2 along fault zones where upward flow transports heat by advection depressed temperatures are observed in eocene and post eocene rapidly subsiding depocenters with overpressure developed below 3000 m 9843 ft older strata along the southeast rifted margin are characterized by a more normal thermal regime evidence from anomalously high temperatures in both map and cross sectional views suggests that fault zones and major regional aquifers accommodate the upward expulsion of fluids from deep overpressured zones many significant petroleum discoveries occur in areas where anomalously high temperatures are observed suggesting that petroleum migration occurs along the same flow networks identifying anomalies in the temperature field may therefore be a useful exploration technique

multiphase breakdown sequence of collapse doline morphogenesis an example from quaternary aeolianites in western australia abstract the morphology of collapse dolines varies according to their maturity and effectiveness of the removal of collapsed material in addition the variable balance between various geomorphic processes due to local geologic hydrologic and climatic settings results in a diverse morphology of collapse dolines and dynamics of their morphogenesis a single generalised proposed sequence of collapse dolines morphogenesis has therefore limited value and more detailed study is needed in terrains which differ in terms of geology hydrology and or climate there is a particularly well exposed karst in stockyard gully national park in the southwestern coastal part of western australia formed in quaternary aeolianites consisting of a dense field of collapse dolines up to 100 m in diameter and on average 10 m deep extensive field work combined with available data of local rock stratigraphy and a comparison to collapse dolines worldwide revealed that the principal processes of collapse doline formation in stockyard gully national park are similar to processes responsible for collapse doline formation worldwide i e collapses above underground chambers and removal of the collapsed material however rock characteristics in the area influence their morphometry due to the mechanical weakness of aeolianite compared to well cemented limestones and a surface calcrete layer with stronger mechanical resistance than underlying aeolianite consequently we propose a new 4 stage multiphase breakdown sequence of collapse doline morphogenesis in aeolianites divided into cave dome calcrete caprock dome young collapse doline and mature collapse doline calcrete caprock dome is stabilised by the uppermost well cemented calcrete and represents a distinctive phase just before the final breakdown to form an actual collapse doline

dead sea sinkholes an ever developing hazard sinkhole development along the western shore of the dead sea became a major concern in 1990 with the appearance of a series of holes 2 15 m diameter and up to 7 m deep in the newe zohar area one of these sinkholes below the asphalt surface of the main road along the western shore of the dead sea was opened by a passing bus repeated infilling and collapse of these holes indicated the extent of this ongoing process and the significance of this developing hazard since then sinkholes have developed in other areas including qalia ein samar ein gedi and mineral beach

a three dimensional insight into the mackenzie basin canada implications for the thermal history and hydrocarbon generation potential of tertiary deltaic sequences the stratal architecture of the mackenzie basin was reconstructed based on seismic and well data and used to define a three dimensional model to reconstruct the so far poorly known thermal and maturation history of the basin to correctly account for the complex tectonic history of the mackenzie basin episodes of uplift and erosion were implemented based on interpretations of original depositional surfaces our results indicate that the combined effects of basin inversion and low surface temperatures inhibited maturation from the late miocene forward in all except the most deeply buried parts of the basin this explains why upper eocene and younger deposits are mostly immature despite their burial to more than 5000 m 16 400 ft the specific history of the basin is shown to control the time intervals of potential hydrocarbon generation predictions of transformation ratios using a variety of published kinetics to account for source rock kinetic variability indicate that potential generation from paleocene and older strata occurred mainly before the late oligocene the generation from eocene strata however occurred mainly during the miocene and therefore is interpreted to be a source for oligocene and younger gas rich reservoirs these findings contribute to a better understanding of hydrocarbon systems in the mackenzie basin and are the basis for future studies of hydrocarbon migration and accumulation

kinematic analysis of vertical collapse on volcanoes using experimental models time series 1 volcanoes are often associated with vertical collapse due to deeper magma withdrawal calderas are the most notable type of vertical collapse on the summit of volcanoes caldera collapse has been observed and monitored only at miyakejima japan 2000 dolomieu reunion 2007 and fernandina galapagos 1968 highlighting our limited knowledge on its kinematic behavior here we use experimental models to investigate the kinematic evolution of calderas and vertical collapses in general we extract velocity and strain fields using the particle image velocimetry piv technique generating time series experimental vertical collapses undergoing constant subsidence velocity show three main kinematic behaviors 1 continuous collapse whose velocity is similar to the source subsidence velocity 2 incremental collapse with episodic stepwise accelerations along pre existing ring structures 3 sudden collapse resulting from the upward migration of a cavity only for t d 2 t and d are the depth and width of the magma chamber respectively and without ring structures the velocity in the collapsing column may increase up to four orders of magnitude with regard to the constant subsidence velocity of the source comparison to nature suggests that 1 there are close kinematic similarities with monitored collapse calderas explaining their incremental subsidence after the development of ring structures 2 sudden pit crater formation is induced by the upward propagation of cavities due to magma removal at depth and in absence of ring structures 3 all these types of vertical collapses have a consistent mechanism of formation and kinematic behavior function of t d and the presence absence of ring structures

sinkhole hazards along the eastern dead sea shoreline area jordan a geological and geotechnical consideration for the last four decades the level of the dead sea has been subjected to continual variation which among other important factors has led to the occurrence of much subsidence and many sinkholes in the southern dead sea area sinkhole activities occurred repetitively and were observed in open farms across roads near dwellings and near an existing factory thus causing a serious threat to the locals and farmers of the area and their properties this paper presents the main results from detailed geological and geotechnical studies of this area aerial photo interpretation and borehole drilling aided these studies parallel geophysical investigations vertical electrical sounding and seismic refraction and hydrological and hydrogeological studies were made by others in the same area to also investigate this phenomenon it was found that sinkholes are aligned to and follow old water channels and are concentrated parallel to the recent shoreline of the dead sea the development of subsurface cavities is associated mainly with the variation in the level of the dead sea over the four past decades the presence of regional salt intrusion under the surface of salt beds the fluctuation of the water table and continuous dissolution and the active tectonism of the area moreover this work showed that the area is still under active sinkhole hazards and other parts of the area will be inevitably affected by sinkholes in the future no practical engineering solution to this problem is feasible

evaluation and modelling of tertiary source rocks in the central arctic ocean abstract with the recently recovered organic rich sediments of early tertiary age from the lomonosov ridge by the integrated ocean drilling program iodp expedition 302 the first data collection directly from source rocks of the central basins of the arctic ocean is now available using the results of seismic interpretations and published sedimentological and organic geochemical data from expedition 302 the framework for the first quantitative assessment of source rock quality and distribution of the palaeogene sediments was modelled in the central arctic ocean the modelling results suggest that an approximately 100 m thick early to middle eocene sedimentary sequence of good to very good source rocks exists along a 75 km long transect across the lomonosov ridge in situ generation of hydrocarbons is unlikely because the overburden 200 250 m and consequently the thermal maturity are too low burial history and thermal modelling reveal that an additional overburden of at least 1000 m is necessary to start hydrocarbon generation along the ridge however source rock modelling results show that good source rock potential may exist in correlative units in the adjacent amundsen basin simulated organic carbon contents of 1 5 5 coupled with an overburden of 1000 1200 m and heat flow anomalies 117 and 100 mw m 2 due to the vicinity to the gakkel ridge spreading centre indicate that necessary conditions for hydrocarbon expulsion are already reached and point to viability of a potential petroleum system our results support the hypothesis that deposition of a potentially good hydrocarbon source rock occurred across the entire arctic basin and adjacent margins during the early tertiary

cave detection and 4 d monitoring a microgravity case history near the dead sea sinkholes large open holes that result from the earth simply collapsing are a serious environmental problem and hazard around the dead sea figure 1 the largest is about 30 m in diameter and 15 m deep figure 2 the most alarming case is a recent collapse on both sides of the main highway at e n gedi a popular destination for recreation and tourism sinkholes initially opened at a campsite east of the road figure 3 subsequently several sinkholes opened west of the road in a palm grove warning of a possible collapse of the highway

sinkholes subsidence and subrosion on the eastern shore of the dead sea as revealed by a close range photogrammetric survey abstract ground subsidence and sinkhole collapse are phenomena affecting regions of karst geology worldwide the rapid development of such phenomena around the dead sea in the last four decades poses a major geological hazard to the local population agriculture and industry nonetheless many aspects of this hazard are still incompletely described and understood especially on the eastern dead sea shore in this work we present a first low altitude our analysis reveals a kilometer scale sinuous depression bound partly by flexure and partly by non tectonic faults the estimated minimum volume loss of this subsided zone is 1 83 106 m3 with an average subsidence rate of 0 21 m yr 1 over the last 25 years sinkholes in the surveyed area are localized mainly within this depression the sinkholes are commonly elliptically shaped mean eccentricity 1 31 and clustered nearest neighbor ratio 0 69 their morphologies and orientations depend on the type of sediment they form in in mud sinkholes have a low depth to diameter ratio 0 14 and a long axis azimuth of nne ne in alluvium sinkholes have a higher ratio 0 4 and are orientated nnw n from field work we identify actively evolving artesian springs and channelized sediment laden groundwater flows that appear locally in the main depression consequently subrosion i e subsurface mechanical erosion is identified as a key physical process in addition to dissolution behind the subsidence and sinkhole hazard furthermore satellite image analysis links the development of the sinuous depression and sinkhole formation at ghor al haditha to preferential groundwater flow paths along ancient and current wadi riverbeds