maturation and bulk chemical properties of a suite of solid hydrocarbons abstract in this paper we present strong correlations of solid hydrocarbon reflectance shro to vitrinite reflectance vro and bulk chemical properties aromaticity tmax h c etc these correlations suggest that like kerogen in coals and sedimentary rocks solid hydrocarbons vary systematically during maturation as a consequence shro is especially useful as a maturity indicator in rocks lacking vitrinite such as pre devonian rocks and many organic rich marine rocks unlike other organic maturationv indicators the utility of solid hydrocarbons is not limited by botanical evolution but rather the generative potential of the petroleum system solid hydrocarbons also known as solid bitumen asphalt dead oil migrabitumen and pyrobitumen are genetically defined as solid phase accumulations of predominantly hydrocarbons produced by petroleum generation in source rocks they may occur over a range of concentrations in outcrop and well samples in all components of petroleum systems although accumulations of solid hydrocarbons from exhumed reservoirs are well reported the extent and utility of disseminated solid hydrocarbons in shales is less understood solid hydrocarbons are found in organic rich to very lean mature rocks as a residual product of generation disseminated solid hydrocarbons exhibit three optical forms anisotropic coked granular and relatively uniform homogenous only the homogenous solid hydrocarbons are recommended for correlation purposes with other thermal indicators

solid bitumen reflectance and rock eval tmax as maturation indices an example from the nordegg member western canada sedimentary basin abstract marine organic rich rock units commonly contain little for vitrinite reflectance v r 0 measurement the most commoly used method of assessing thermal maturity this is true of the lower jurassic nordegg member a type i ii sulphur rich source rock from the western canada sedimentary basin this study examines the advantages and pitfalls associated with the use of rock eval t max and solid bitumen reflectance b r 0 to determined maturity in the nordegg vitrinite reflectance data from cretaceous coals and known coalification gradients in the study area are used to extrapolate v r 0 values for the nordegg t max increases non linearly with respect to both b r 0 and extrapolated v r 0 values a sharp increase in the reflectaance of both solid bitumen and vitrinite occurs between t max 440 450 c and is coincident with a pronounced decrease in hydrogen index values and the loss of solid bitumen and telalginite fluorescence over the same narrow t max interval this t max range is interpreted as the main zone of hydrocarbon generation in the nordegg and corresponds to extrapolated v r 0 values of 0 55 0 85 the moderate to high sulphur contents in the kerogen played a significant role in determining the boundaries of the nordegg oil window a linear relationship between b r 0 and extrapolated v r 0 as proposed elsewhere is not true for the nordegg b r 0 increases with respect to extrapolated v r 0 according to jacob s 1985 formula v r 0 0 618 b r 0 0 40 up to v r 0 0 72 b r 0 0 52 beyond this point b r 0 increases sharply relative to extrapolated v r 0 according to the relatioship v r 0 0 277 b r 0 0 57 r 2 0 91 the break in the b r 0 v r 0 curve at 0 72 v r 0 is thought to signifiy the peak of hydrocarbon generation and represents a previously unrecognized coalification jump in the solid bitumen analogous to the first coalification jump of liptinites

phanerozoic evolution of the basins of northern egypt and adjacent areas the results of integrating geological well data and geophysical information from the subsurface of northern egypt are presented in terms of basin dynamics recent biostratigraphic data from wells and scarce outcrops are shown to be critical to an understanding of syndepositional tectonics six tectonostratigraphic phases of basin evolution are recognized to span the phanerozoic these phases initially record the development of intracratonic subsidence controlled by deep crustal strike slip tectonics as nubian continental and tethyan marine influences competed across the northern margin of gondwanaland evidence is also presented for the formation of the present day continental margin to northern egypt after a phase of crustal stretching oceanic rifting focused on the western margin of the arabian platform propagating progressively westwards during the early mid jurassic thereafter the effects of passive subsidence on the continental margin were disturbed by discrete phases of intracratonic strike slip associated syrian arc folding and the formation of deep basins in the opening red sea and gulf of suez three structural fabrics persisted throughout phanerozoic basin evolution the result of repeated extensional reactivation and inheritance from pan african basement

topographic slope as a proxy for seismic site conditions and amplification we describe a technique to derive first order site condition maps directly from topographic data for calibration we use global 30 arc sec topographic data and v s 30 measurements here v s 30 refers to the average shear velocity down to 30 m aggregated from several studies in the u s as well as in taiwan italy and australia v s 30 values are correlated against topographic slope to develop two sets of parameters for deriving v s 30 one for active tectonic regions where topographic relief is high and one for stable shields where topography is more subdued by taking the gradient of the topography and choosing ranges of slope that maximize the correlation with shallow shear velocity observations we can recover to first order many of the spatially varying features of sitecondition maps developed for california our site condition map for the low relief mississippi embayment also predicts the bulk of the v s 30 observations in that region despite rather low slope ranges we find that maps derived from the slope of the topography is often well correlated with other independently derived regional scale site condition maps but the latter maps vary in quality and continuity and subsequently also in their ability to match observed v s 30 measurements contained therein alternatively the slope based method provides a simple approach to uniform site condition mapping

a terrain based site conditions map of california with implications for the contiguous united states abstract we present an approach based on geomorphometry to predict material properties and characterize site conditions using the v s 30 parameter time averaged shear wave velocity to a depth of 30 m our framework consists of an automated terrain classification scheme based on taxonomic criteria slope gradient local convexity and surface texture that systematically identifies 16 terrain types from 1 km spatial resolution 30 arcsec shuttle radar topography mission digital elevation models srtmdems using 853 v s 30 values from california we apply a simulation based statistical method to determine the mean v s 30 for each terrain type in california we then compare the v s 30 values with models based on individual proxies such as mapped surface geology and topographic slope and show that our systematic terrain based approach consistently performs better than semiempirical estimates based on individual proxies to further evaluate our model we apply our california based estimates to terrains of the contiguous united states comparisons of our estimates with 325 v s 30 measurements outside of california as well as estimates based on the topographic slope model indicate our method to be statistically robust and more accurate our approach thus provides an objective and robust method for extending estimates of v s 30 for regions where in situ measurements are sparse or not readily available

a shallow shear wave velocity transect across the reno nevada area basin in october and november 2001 we performed an urban shear wave velocity transect across 16 km of the reno nevada area basin using the refraction microtremor method of louie 2001 we determined shear wave velocity versus depth profiles at 55 locations shear wave velocity averaged to 30 m depth vs30 is one predictor of earthquake ground motion amplification in similar alluvium filled basins and it is the basis of site hazard classification under national earthquake hazards reduction program uniform building code nehrp ubc provisions a geologic map based nehrp classification along nearly all of our transect line would be nehrp d but our measurements of vs30 revealed that 82 of the transect is classified nehrp c relatively stiff tertiary sediments underlie the surface of the reno basin and weaker soils occur east of downtown reno in the floodplain of the truckee river although 53 of our locations were on the geologically youngest and most active fluvial units these sites showed vs30 values ranging from 286 m sec nehrp d to 849 m sec nehrp b mapped geologic and soil units are not accurate predictors of vs30 measurements in this urban area a test model based on gravity results showed quaternary alluvium depth can be combined with transect vs30 mea surements to predict vs30 across the reno basin

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

organic rich sedimentation at the cenomanian turonian boundary in oceanic and coastal basins in the north atlantic and tethys one of the most striking results of the deep sea drilling project is the proof that organic rich sediments have a widespread geographical distribution during the period from upper cenomanian to middle turonian such sediments were drilled at north atlantic dsdp sites 105 135 137 138 367 398 551 603 they are also present from outcrops or oil wells on the shelf of the african continental margin senegal tarfaya and agadir basins in the tethys former alboran block southern spain algeria tunisia and umbrian apennines italy and in the north sea although these sediments have different lithologies and depositional environments from shelf areas to the deep sea their study mainly based on organic geochemistry with additional data on sedimentology biostratigraphy and palaeo bathymetry suggests that a unique pulse of organogenic accumulation characterizes the cenomanian turonian boundary event ctbe the content and type of organic matter are related to the depositional environment and organic preservation the organogenic accumulation is distributed according to various trends off the african continental margin the organic content increases from onshore areas to the shelf casamance area and moreover increases also in deep sea areas with a gradual transition from terrestrial type iii to marine type ii the best preservation of the organic matter being in the deepest areas i e site 367 off the american continental margin site 603 shows the same toc and type of organic matter as at site 105 the ctbe is also well recorded in the northern part of the atlantic celtic margin north sea by a drastic lithological change black shales within chalks but the type of organic matter is mainly terrestrial in the tethyan area the organic matter is of marine origin and well preserved results are compared with those of pratt 1984 from the western interior basin of the usa different hypotheses to explain this synchronous widespread accumulation of organic matter are discussed 1986 the geological society

vs30 empirical prediction relationships based on a new soil profile database for the beijing plain area china earthquake ground motion prediction models usually define site conditions based on the time averaged shear wave velocity in the upper 30 m v s 30 proxy based estimations of v s 30 are commonly used if velocity measurements are not available we compile a soil profile database for the beijing plain area china using data from research documents and technical reports the database contains 479 soil profiles 463 of which have depths greater than 30 m we develop regional relationships for the beijing plain area for extrapolating the time averaged shear wave velocity to a given depth less than 30 m to v s 30 and then compare the performance of available models we find that the second order polynomial model boore et al 2011 based on data from japan provides an overprediction whereas the linear model boore 2004 calibrated on data from california underestimates v s 30 we develop relationships for estimating v s 30 based on proxies such as ground slope gradients from radar derived digital elevation models dems and surface geology at different scales we find that local v s 30 data in the beijing plain are generally lower than existing 30 arcsec gradient based global models regression results show a modest correlation between v s 30 and topographic ground slope for several dem resolutions 3 15 30 and 60 arcsec geology based proxies are more effective than ground slope for v s 30 estimation in the analyzed area we propose a bilinear model based on geologic ages and depositional environments for estimating v s 30 which shows a statistically significant trend for application in the beijing plain area online material figures showing topographic ground slopes and correlations of v s 30 with topographic slope from digital elevation model dem data and a table summarizing data from the 463 boreholes

experimental study of geo acoustic inversion uncertainty due to ocean sound speed fluctuations acoustic data measured in the ocean fluctuate due to the complex time varying properties of the channel when measured data are used for model based geo acoustic inversion how do acoustic fluctuations impact estimates for the seabed properties in may 1999 saclant undersea research center and tno physics and electronics laboratory fel conducted a shallow water experiment on the adventure bank off the southwest coast of sicily italy to assess the effects of a time varying ocean on acoustic propagation and geo acoustic inversion a favorable area for acoustic propagation was identified which had slight internal wave activity and a weakly range dependent bathymetry with sand like bottom properties oceanographic and acoustic measurements were performed continuously over a 3 day period broadband 0 2 3 8 khz acoustic signals from a bottom moored source were transmitted over fixed paths and received on a moored vertical hydrophone array during the transmissions extensive environmental measurements e g sound speed current sea surface waveheight etc were made to correlate the time varying environmental and acoustic data modeled acoustic data show time variability which agrees with the measurements results illustrate severe problems when modeling shallow water acoustic propagation at ranges beyond a few kilometers in the frequency band considered further the acoustic fluctuations in time caused erroneous time variability in inverted seabed properties

guidelines for evaluating petroleum source rock using programmed pyrolysis rock eval pyrolysis is used to rapidly evaluate the petroleum generative potential and thermal maturity of rocks accurate conclusions require programs every 30 60 ft 9 18 m understanding of interpretive pitfalls and supporting data such as visual kerogen vitrinite reflectance and elemental analyses the generative potential of coals is commonly overestimated by pyrolysis and is best determined by elemental analysis and organic petrography most coals show high s2 s3 5 and low hi values 300 mg hc g toc migrated oil and mud additives which alter rock eval data can sometimes be removed by special processing for immature rocks bimodal s2 peaks and pi values over 0 2 indicate contamination pyrolysis downgrades organic poor clay rich rocks which show lower hi and higher tmax values than isolated kerogen because of adsorption of pyrolyzate on the clays tmax values for small s2 peaks 0 2 mg hc g toc are unreliable tmax is affected by maturation organic matter type contamination and the mineral matrix s3 is sensitive to inorganic and adsorbed carbon dioxide and to instrumentation problems acidification of carbonate rich samples and proper maintenance improves s3 measurement constant sample weights 100 mg are recommended below a threshold weight tmax increases by up to 10 c and other parameters decrease organic rich samples which overload the detector can be diluted with carbonate detector linearity is determined by pyrolyzing various weights of an organic rich rock

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

a vs30 map for california with geologic and topographic constraints abstract for many earthquake engineering applications site response is estimated through empirical correlations with the time averaged shear wave velocity to 30 m depth v s 30 these applications therefore depend on the availability of either site specific v s 30 measurements or v s 30 maps at local regional and global scales because v s 30 measurements are sparse a proxy frequently is needed to estimate v s 30 at unsampled locations we present a new v s 30 map for california which accounts for observational constraints from multiple sources and spatial scales such as geology topography and site specific v s 30 measurements we apply the geostatistical approach of regression kriging rk to combine these constraints for predicting v s 30 for the v s 30 trend we start with geology based v s 30 values and identify two distinct trends between topographic gradient and the residuals from the geology v s 30 model one trend applies to deep and fine quaternary alluvium whereas the second trend is slightly stronger and applies to pleistocene sedimentary units the rk framework ensures that the resulting map of california is locally refined to reflect the rapidly expanding database of v s 30 measurements throughout california we compare the accuracy of the new mapping method to a previously developed map of v s 30 for california we also illustrate the sensitivity of ground motions to the new v s 30 map by comparing real and scenario shakemaps with v s 30 values from our new map to those for existing v s 30 maps online material california statewide v s 30 and shakemaps for loma prieta

milankovitch climatic origin of mid cretaceous black shale rhythms in central italy the earth s orbital variations reflected in pleistocene ice volume were also recorded in non glacial times carbonate production in pelagic mid cretaceous sediments quantified by calcium carbonate and optical densitometry time series reflects the orbital eccentricity and precessional cycles minimal eccentricity brought deep sea anoxia most of the sedimentary variability of this 100 myr old sequence lies within the milankovitch orbital frequency band

origin of marine petroleum source rocks from the late jurassic to early cretaceous norwegian greenland seaway evidence for stagnation and upwelling abstract forty samples were selected from upper jurassic to lower cretaceous black shales of iku sites 6307 07 u 02 and 6814 04 u 02 located on the mid norwegian shelf for a detailed maceral analysis the penetrated rocks include the spekk and hekkingen formations which represent major potential petroleum source rocks in the region it was our first objective to reveal the type of organic material that is responsible for the source rock potential of these sediments the results suggest that black shale formation has occurred in two different paleoceanographic settings 1 in a high productive and 2 an anoxic stagnant environment this conclusion is supported by inorganic and sedimentological data in addition sedimentation rates sr from recent biostratigraphic and sedimentological work on these sequences gave impulse for using accumulation rates to estimate the original organic carbon flux to the sediment organic carbon accumulation rates are relatively low but similar to mid cretaceous black shales from other ocean areas average 10 300 mg cm 2 ka supported by redox sensitive re mo ratios sr toc relationships and paleoproductivity estimates we suggest that the formation and preservation of organic carbon during black shale formation in the spekk formation has followed largely the conditions of the stagnation model whereas the hekkingen formation is likely one possible example for the productivity model

regional correlations of vs30 and velocities averaged over depths less than and greater than 30 meters using velocity profiles from sites in japan california turkey and europe we find that the time averaged shear wave velocity to 30 m vs30 used as a proxy for site amplification in recent ground motion prediction equations gmpes and building codes is strongly correlated with average velocities to depths less than 30 m vsz with z being the averaging depth the correlations for sites in japan corresponding to the kik net network show that vs30 is systematically larger for ag ivenvsz than for profiles from the other regions the difference largely results from the placement of the kik net station locations on rock and rocklike sites whereas stations in the other regions are generally placed in urban areas underlain by sediments using the kik net velocity profiles we provide equations relating vs30 to vsz for z ranging from 5 to 29 m in 1 m increments these equations and those for california velocity profiles given in boore 2004b can be used to estimate vs30 from vsz for sites in which velocity profiles do not extend to 30 m the scatter of the residuals decreases with depth but even for an averaging depth of 5 m a variation in logvs30 of 1 standard deviation maps into less than a 20 uncertainty in ground motions given by recent gmpes at short periods the sensitivity of the ground motions to vs30 uncertainty is considerably larger at long periods but is less than a factor of 1 2 for averaging depths greater than about 20 m we also find that vs30 is correlated with vsz for z as great as 400 m for sites of the kik net network providing some justification for using vs30 as a site response variable for predicting ground motions at periods for which the wavelengths far exceed 30 m online material estimates of vs30 at k net stations

metamorphism of carbonaceous material in the tono contact aureole kitakami mountains japan abstract optical and x ray studies of carbonaceous material in the tono contact metamorphic aureole kitakami mountains northeast japan have revealed that metamorphic graphitization proceeded through two discontinuous changes first optically anisotropic domains develop within the coaly phytoclast forming transitional material and then ordered graphite crystallizes by the decomposition of pre existing carbonaceous materials coaly material disappears in the uppermost chlorite zone transitional material appears in the middle of the lower chlorite zone graphite appears in the upper chlorite zone and its modal abundance increases across the andalusite iso grad to the cordierite isograd where all the carbonaceous materials have converted to graphite the apparently continuous variation in the crystallographic parameters of the bulk carbonaceous material during graphitization is largely due to variation in the modal proportions of three types of carbonaceous materials the temperature of graphitization in the present area is at least 100 c higher than the temperature in the sanbagawa and new caledonia high pressure metamorphic terrains probably due to the slow reaction rate of metamorphic graphitization and to the short duration of contact metamorphism

developing a map of geologically defined site condition categories for california consideration of site conditions is a vital step in analyzing and predicting earthquake ground motion the importance of amplification by soil conditions has long been recognized but though many seismic instrument sites have been characterized by their geologic conditions there has been no consistent simple classification applied to all sites as classification of sites by shear wave velocity has become more common the need to go back and provide a simple uniform classification for all stations has become apparent within the pacific earthquake engineering research center s next generation attenuation equation project developers of attenuation equations recognized the need to consider site conditions and asked that the california geological survey provide site conditions information for all stations that have recorded earthquake ground motion in california to provide these estimates we sorted the available shear wave velocity data by geologic unit generalized the geologic units and prepared a map so that we could use the extent of the map units to transfer the velocity characteristics from the sites where they were measured to sites on the same or similar materials this new map is different from the california geological survey preliminary site conditions map of california in that 19 geologically defined categories are used rather than national earthquake hazards reduction program categories although this map does not yet cover all of california when completed it may provide a basis for more precise consideration of site conditions in ground motion calculations

a review of the tectonics of the northern middle east region the structure of the northern part of the arabian platform is reviewed in the light of hitherto unpublished exploration data and the presently accepted kinematic model of plate motion in the region the palmyra and sinjar zones share a common history of development involving two stages of rifting one in the triassic jurassic and the other during late cretaceous to early tertiary times deformation of the palmyra zone during the mio pliocene is attributed to north south compression on the eastern block of the dead sea transcurrent system which occurred after continental collision in the north in southeast turkey the asymmetry of the palmyra zone is believed to result from northward underthrusting along the southern boundary facilitated by the presence of shallow triassic evaporites an important nw se cross plate shear zone has been identified which can be traced for 600 km and which controls the course of the river euphrates over long distances in syria and iraq transcurrent motion along this zone resulted in the formation of narrow grabens during the late cretaceous which were compressed during the mio pliocene to a large extent present day structures in the region result from compressional reactivation of old lineaments within the arabian plate by the transcurrent motion of the dead sea fault zone and subsequent continental collision

compilation of a local vs profile database and its application for inference of vs30 from geologic and terrain based proxies abstract the time averaged shear wave velocity in the upper 30 m of a site v s 30 is commonly used for ground motion prediction when measured velocities are unavailable v s 30 is estimated from proxy based relationships developed for application on global or local scales we describe the development of a local relationship for greece which begins with compilation of a profile database pdb from published sources and engineering reports the pdb contains 314 sites 238 have profile depths 30 m and 59 are within 100 m of accelerographs we find existing relations for extrapolating a time averaged velocity for depths less than 30 m to v s 30 to overpredict v s 30 we present equations for these extrapolations we then compile proxies for pdb sites including terrain type surface geology and surface gradients at 30 and 3 arcsec resolution from radar derived digital elevation models dems when checked against ground survey data we find ground elevations from 3 arcsec dems to be more accurate relative to survey data than alternative 30 9 and 1 arcsec dems drawing upon expert opinion we develop geologic categories based on age gradation and depositional environment and assign such categories to pdb sites we find an existing 30 arcsec gradient based global model to be biased relative to local v s 30 data for gradients 0 05 m m bias relative to a california model is also found for four of the eight well populated geomorphic categories and new local values are provided we find statistically significant effects of the 3 arcsec gradient on v s 30 for quaternary and tertiary materials but no gradient effect for those from the mesozoic among quaternary sediments holocene mapped quaternary age unspecified and mixed fine gradation materials exhibit consistent v s 30 gradient trends whereas pleistocene and coarse gradation sediments have faster velocities for the study region we recommend use of the modified terrain and geology based methods in combination for proxy based v s 30 estimation online material profile database spreadsheet and figures of elevation residuals

coalification and graphitization of graptolites in the anchizone and lower epizone abstract in lower paleozoic sediments of the south alpine carnic alps carinthia austria fragments of graptolites were used to trace the process of coalification and graphitization in a continuous anchizonal to epizonal metamorphic section beginning with the onset of meta anthracitic coal ranks the process of graphitization produces graptolites with the structure of coke like transitional matter the path of coalification of graptolite fragments is explained by the model of a reflectance indicating surface ris this path resembles the coalification of vitrinite during the process of coalification the shape of the ris shows a non coaxial evolution starting with a primary biaxial negative geometry the oblate graptolite ris shapes of the carnic alps are indicative of a metamorphic event with only minor tectonic influence

amplification factors for spectral acceleration in tectonically active regions empirical relationships are developed to predict amplification factors for 5 damped response spectral acceleration period range t 0 01 5 sec as a function of site category we evaluate amplification factors by normalizing response spectral accelerations computed from recordings by reference spectral accelerations derived from a modified attenuation relationship for active regions strong motion sites are categorized according to several schemes which are based on surface geology age only age depositional environment and age material texture shallow 30 m shear wave velocity and geotechnical data criteria for selection of the optimal classification scheme are that the amplification models for categories within the scheme 1 minimize the global dispersion of prediction residuals and 2 are significantly distinct across a broad period range the results of the regressions indicate that the greatest levels of distinction in amplification levels across categories occur for the shallow shear wave velocity scheme but that the dispersion of residuals for this scheme are relatively high for soil sites although not for rock sites conversely schemes based on detailed surface geology generally have the smallest dispersion for soil sites but amplification levels across quaternary categories are only significantly distinct at small periods these findings suggest that detailed surface geology provides an effective means of soil site categorization at small periods whereas shallow shear wave velocity provides an effective means for rock site categorization at small periods at longer periods none of the schemes are optimized relative to both the dispersion and distinction criteria the principal application of the amplification factors is as a modifier of attenuation relations much like a site term the present results significantly reduce the bias associated with the site terms in a widely used attenuation relationship for rock and soft soil site conditions manuscript received 25 february 2002

accumulation of organic carbon rich sediments in the late jurassic and cretaceous atlantic ocean a synthesis abstract organic carbon rich sediments black shales were deposited at some 40 deep sea drilling project dsdp sites in the atlantic ocean during late jurassic and cretaceous times in order to reconstruct the depositional environments of black shale formation we have studied in detail changes in the occurrence of black shales as well as the type and amount of organic matter in relation to changes in paleogeography paleooceanic circulation and paleoclimate we have calculated accumulation rates of marine and terrigenous organic carbon and combined these with organic carbon content sedimentation rate relationships to obtain information about paleoenvironments main factors causing the preservation and accumulation of organic carbon are 1 the supply of terrestrial organic matter 2 the supply of marine organic matter 3 the oxygenation of the deep water and 4 the bulk sedimentation rate changes in the importance of these different factors and changes in the interrelationships among them determine the complex system of black shale formation and their cyclic variations increased supply of terrestrial organic matter due to increased river discharge and humid climate in northeast america southwest europe and south africa were important in the hauterivian albian northwest and northern northeast atlantic and in the late jurassic aptian south atlantic in the latter anoxic deep water conditions due to restricted circulation in the nascent largely isolated basin as well as higher oceanic productivity may have reinforced the high preservation rates of marine organic matter during that time off northwest africa higher flux rates of marine organic matter were recorded in areas of higher productivity which may have been caused by fluvial nutrient supply during the hauterivian and by intensified upwelling during albian turonian times in general the depositional environment was oxygenated and the content of marine organic matter was a function of the sedimentation rate furthermore at some places redeposition by turbidity currents or slumps may have been important for the accumulation of organic matter in the deep sea basins the only episode of widespread anoxia in the western and eastern basins of the north atlantic may have occurred in the cenomanian turonian when high amounts of marine organic matter were also preserved in areas of low productivity and low sedimentation rates

rejuvenation of the tethyan passive continental margin of northern sinai deformation style and age gebel yelleq area abstract detailed field mapping and structural analysis of the northeastern and southeastern parts of gebel yelleq the largest fold among the northern sinai folds indicate the presence of two ene oriented dextral wrench zones the northern meneidret el etheili wrench zone is represented by right stepped en echelon doubly plunging folds whereas throughgoing wrench faults characterize the southern minsherah wrench zone the steep southeastern flank of gebel yelleq asymmetric fold makes an acute angle with the wrench zones and is orthogonal to the nw se directed shortening direction indicated by mesostructures similar structural relations are evident in the other major folds of northern sinai gebels el maghara and halal a structural model is proposed for the deformation of northern sinai late cretaceous tertiary rejuvenation of the early mesozoic passive continental margin of the neotethys proceeded via right lateral wrenching in northern sinai and is related to the oblique convergence between africa arabia and eurasia during the closure of the neotethys as a result wrench zones developed above the early rift faults e g meneidret el etheili and minsherah wrench zones also nw se directed shortening related to and parallel to the convergence of africa arabia and eurasia deformed the blocks lying between the wrench zones through the development of ne sw oriented thrust faults at acute angles to the wrench zones these thrusts ruptured the precambrian basement and propagated upward through the overlying sedimentary cover as listric thrust faults forming large fault propagation folds in gebels yelleq el maghara and halal these thrusts underlie the steep southeastern flanks of these folds and are exposed in gebels el maghara and hamayir the depth to detachment of these thrusts progressively increases southward to a value underneath the gebel yelleq area close to the brittle ductile transition of the crust the deformation reached its zenith in the early late senonian and probably continued into the early miocene the northern sinai fold belt characterizes an unstable crustal block separated from a tectonically stable crustal block to the south in central and southern sinai by a belt of ene oriented closely spaced faults forming what is called the central sinai hinge belt

compressive acoustic sound speed profile estimation ocean acoustic sound speed profile ssp estimation requires the inversion of acoustic fields using limited observations compressive sensing cs asserts that certain underdetermined problems can be solved in high resolution provided their solutions are sparse here cs is used to estimate ssps in a range independent shallow ocean by inverting a non linear acoustic propagation model it is shown that ssps can be estimated using cs to resolve fine scale structure

organic facies and thermal maturity of late aptian to early cenomanian shelf deposits northern sinai egypt abstract organic petrologic and geochemical investigations were carried out on late aptian to early cenomanian mid cretaceous sediments recovered from the paleoshelf of the northern sinai egypt the organic facies and thermal maturity of sedimentary organic matter were evaluated with regard to maximum burial depth results from organic geochemical analyses c org n tot rock eval pyrolysis performed on kerogen concentrates indicate the dominance of hydrogen depleted organic matter of either terrestrial or degraded marine origin kerogen typing reveals a mixture of type iii and iv maceral analyses conducted on concentrates support geochemical results showing variable proportions of vitrinite migrabitumen graphite and traces of inertinite vitrinite and inertinite are considered to be of autochthonous or parautochthonous origin indicating at least partly humid paleoclimatic conditions in the hinterland this assumption is also supported by the occurrence of graphite which points to aquatic transport from the southerly exposed precambrian basement the presence of migrabitumen presumably relates to migrated hydrocarbons from underlying organic carbon rich jurassic strata the organic facies of mid cretaceous deposits from the northern sinai indicates a proximal fluvio deltaic or oxic shelf environment equivalent to organic facies types c d according to jones jones r w 1987 organic facies in brooks j welte d h eds advances in petroleum geochemistry academic press london pp 1 80 t max data obtained from rock eval pyrolysis reveal an immature level for organic matter 350 c to 425 c although these values are probably depressed due to the presence of migrabitumen since vitrinite is very scarce in kerogen concentrates reflectance measurements were also performed on migrabitumen the best correlation of both types of reflectance data was obtained when migrabitumen data were corrected following the approach of jacob jacob h 1989 classification structure genesis and practical importance of natural solid oil bitumen int j coal geology 11 pp 65 79 reflectance values range between 0 6 to 0 7 rm equivalent to high volatile bituminous coalification stages since there is no indication for an abnormal geothermal gradient along the ne african margin a maximum burial depth between 1 2 km and 2 0 km is estimated for the mid cretaceous strata of the northern sinai

predictions of shear wave velocities in southern california using surface geology a new model of the average shear wave velocity in the uppermost 30 m has been generated by extrapolation of discrete velocity profiles using surface geology at several scales statistical methods have been applied to create a map that is no more complicated than is supported by the velocity data several geologic units with similar responses are grouped together the resulting map is simpler than previous ones and yet fits the observed velocity profiles better than earlier more complicated maps analysis within a geographic information system will permit updates and modification of the map as new velocity data are added

effect of ocean sound speed uncertainty on matched field geoacoustic inversion the effect of ocean sound speed uncertainty on matched field geoacoustic inversion is investigated using data from the sw06 experiment along a nearly range independent bathymetric track significant sound speed differences were observed at the source and receiving array and several environmental parameterizations were investigated for the inversion including representing the ocean sound speed at both source and receivers with empirical orthogonal function eof coefficients a genetic algorithm based global optimization method was applied to the candidate environmental models then a bayesian inversion technique was used to quantify uncertainty in the environmental parameters for the best environmental model which included an eof description of the ocean sound speed