a study on the regulation of the concentrations of some trace metals rb sr zn pb cu v cr ni mn and mo in saanich inlet sediments british columbia canada abstract bulk metal concentrations were measured in the sediments of saanich inlet in an attempt to establish the occurrence of trace metal enrichment in the anoxic central basin ba ni v cr zn pb cu and mo were found to be enriched in the anoxic ooze over the possible contributions from lithogenic sources spatial and seasonal variations in the chemical composition of the settling particulates collected with interceptor traps gave further indications of the mode of incorporation of these metals biogenic ba and cr appeared to be associated with opaline silica although alternative explanations are also possible particularly for ba zinc seemed to be added to the sediment essentially in association with planktonic materials while cu required an additional source directly linked to the anoxic environment similarly ni v and mo were added to the anoxic sediments by reactions occurring at the sediment water interface in the nearshore environment studied here these metals particularly ni and mo were not associated to any significant extent with planktonic materials of all the elements analyzed mo showed the largest enrichment in the anoxic sediments of saanich inlet

recent sediment accumulation and origin of shelf mud deposits in the yellow and east china seas abstract modern last 100 yr accumulation rates of shelf mud deposits in the yellow and east china seas were investigated using the distribution of excess 210pb 210pbex in sediment core samples compilation and merger of new and previously published data helped clarify sediment accumulation in these seas the estimated accumulation rates together with data of suspended sediment concentrations provided findings on the sediment budget origin and transport pathway of the mud deposits the overall accumulation distribution in the yellow and east china sea shelf revealed a general cross shelf decreasing trend along the sediment dispersal system away from the rivers except for the south sea ssm and southeastern yellow sea seysm mud patches found along the korean coast notably 210pbex activity profiles within the ssm and the seysm yielded a relatively high accumulation rate of 2 5 mm yr implying a sedimentation rate of 4 15 107 tons per year in this coastal zone such an annual accumulation rate is about one order of magnitude greater than the total sediment discharge 6 20 106 tons yr from korean rivers suggesting an additional offshore source the distribution pattern of the well defined suspended plume clearly showed the possible transport and exchange of fine grained sediments between the ecs shelf and the coastal area of korea especially during winter such a high accumulation in korean coastal areas is attributable to the sediments supplied from the mud deposit of the ecs i e swcim with origins in chinese rivers therefore the korean coastal area may be an important sink for some of chinese river sediments being transported from the south by the yellow sea warm current

geochemistry of surface sediments in the southwestern east japan sea abstract we analyzed 77 surface sediment samples collected in the southwestern east japan sea from the korea strait through the ulleung basin and the korea plateau for grain size calcium carbonate organic carbon and major na mg al fe k ca and ti and trace elements p mn sr li sc v cr co ni zn cu and pb the chemical composition of the surface sediments was found to be highly variable spatially cluster analysis of surface sediment chemical compositions indicated five major geochemical sedimentary environments basin lower slope coast and upper slope inner shelf and outer shelf continental shelf sediments were rich in shell fragments and had relict and coarse grained characteristics recent fine grained sediments were only distributed in coastal slope and basin areas concentrations of al k ca ti cr and sc were highest in the coastal and upper slope areas and decreased with water depth elemental ratios using major and trace elements indicated that coastal and upper slope detrital sediments were mixtures of sediments derived from the changjiang yangtze and nakdong rivers although the concentrations of organic carbon p mn v co ni cu and pb increased with water depth their distribution patterns indicated authigenic v cu and pb and diagenetic fe p mn co and ni origins the distribution pattern with water depth suggested that the chemical composition of surface sediment was determined by sedimentologic and geochemical processes such as the supply of detrital and biogenic materials and authigenic and post depositional diagenetic processes in sediments

the composition and evolution of the continental crust rare earth element evidence from sedimentary rocks the composition of the present day upper crust inferred from the uniformity of sedimentary rock r e e rare earth element patterns is close to that of granodiorite a revised andesite model is used to obtain total crustal composition the lower crust is the composition remaining assuming that the upper crust one third of the total is derived from intracrustal partial melting the upper crustal r e e pattern has pronounced eu depletion eu eu 0 64 the lower crustal pattern has eu enrichment eu eu 1 17 and the total crust has no eu anomaly relative to chondritic abundances the eu depletion in the upper crust is attributed to retention of eu in plagioclase in the lower crust because plagioclase is not stable below 40 km 10 kbar the anomaly is intracrustal in origin the archaean upper crust has a different r e e pattern to that of the present day upper crust being lower in total r e e and la yb ratios and lacking an eu anomaly these data are used to infer the archaean upper crustal composition which resembles that of the present day total crust except that ni and cr contents are higher the archaean crustal composition can be modelled by a mixture of tholeiites and tonalite trondhjemites the latter have steep light r e e enriched heavy r e e depleted patterns consistent with equilibration with garnet and hence probable mantle derivation there is little reason to suppose that the archaean lower crust was different in composition from the upper crust except locally where partial melting episodes occurred the r e e evidence is consistent with isotopic and geological evidence for a low continental growth rate in the early archaean a massive increase to about 70 of the total crust between about 3000 and 2500 ma b p and a slow increase until the present day the change from archaean to post archaean r e e patterns in the upper crust is not isochronous but is reflected in the sedimentary rock r e e patterns at differing times in different continents on the basis of a model composition for the mantle 36 of the potassium 30 of uranium 15 of lanthanum and 3 of ytterbium are concentrated in the present continental crust this enrichment is related to ionic size and valency differences from common mantle cations e g mg fe pre 3 9 ga b p crusts were obliterated by meteorite bombardment no geochemical evidence exists for primordial anorthositic sialic or mafic crusts

grain size effect on multi element concentrations in sediments from the intertidal flats of bohai bay china abstract in the intertidal flats of bohai bay china the spatial distribution of the grain size of sediments becomes coarser from landward to seaward to study the grain size effect on multi element concentrations in sediments samples along the coastline and 3 horizontal cross sections were collected from the intertidal flats of bohai bay china in 1998 total concentrations of 49 elements including alkali alkaline earth trace metal rare and rare earth elements were measured by icp aes icp ms and inaa the results show that sediment texture plays a controlling role on the concentrations and their spatial distribution principal component analysis and cluster analysis were carried out based on the grain sizes of the sediments and the samples were classified into 3 groups mud silt mud and silt significant differences among the element concentrations in the 3 groups were observed and the concentrations of the elements in each group are reported in this study most of the elements have their highest concentrations in the fine grained mud samples in comparison with the silt and silt mud samples with clay minerals possibly playing an important role in contrast concentrations of ba sr hf and zr are elevated in the coarse silt samples ba and sr may reside in feldspars while zr and hf are present in zircons landward to seaward spatial variation of element concentrations in the sediments is observed which is in line with the spatial distribution of the grain size and is related to the seawater hydrological dynamics in the intertidal flats

late quaternary paleoenvironmental changes in the southeastern yellow sea korea abstract a 34 meter long ams 14 c dated sediment core was examined in order to reconstruct the paleoenvironmental changes that have taken place in the southeastern yellow sea during the last 16 600 years to achieve this we analyzed the geochemical compositions of organic matter the benthic foraminiferal assemblages and the stable isotopes of benthic foraminiferal tests the organic geochemical results show that terrigenous organic matter was dominant in the southeastern yellow sea between 16 600 and 4300 cal yr bp probably due to the influence of river runoff marine organic matters originating from surface primary productivity began increasing drastically after 4300 cal yr bp benthic foraminiferal assemblages reveal that brackish species were dominant before 3500 cal yr bp but the saline species dominated after this time the 18 o values of the benthic foraminifer cibicides lobatulus showed that a change from high amplitude to low amplitude fluctuations took place at 3500 cal yr bp these multi results indicate that the southeastern yellow sea changed from an estuarine to a modern marine shelf environment probably due to the inflow of the yellow sea warm current between 4300 and 3500 cal yr bp the time discrepancy of 800 years indicates that a modern marine shelf environment was not fully developed in the southeastern yellow sea until 3500 cal yr bp even though the sea began to be influenced by the oceanic current at 4300 cal yr bp

snow instability patterns at the scale of a small basin spatial and temporal variations are inherent characteristics of the alpine snow cover spatial heterogeneity is supposed to control the avalanche release probability by either hindering extensive crack propagation or facilitating localized failure initiation though a link between spatial snow instability variations and meteorological forcing is anticipated it has not been quantitatively shown yet we recorded snow penetration resistance profiles with the snow micropenetrometer at an alpine field site during five field campaigns in eastern switzerland for each of about 150 vertical profiles sampled per day a failure initiation criterion and the critical crack length were calculated for both criteria we analyzed their spatial structure and predicted snow instability in the basin by external drift kriging the regression models were based on terrain and snow depth data slope aspect was the most prominent driver but significant covariates varied depending on the situation residual autocorrelation ranges were shorter than the ones of the terrain suggesting external influences possibly due to meteorological forcing to explore the causes of the instability patterns we repeated the geostatistical analysis with snow cover model output as covariate data for one case the observed variations of snow instability were related to variations in slab layer properties which were caused by preferential deposition of precipitation and differences in energy input at the snow surface during the formation period of the slab layers our results suggest that 3 d snow cover modeling allows reproducing some of the snow property variations related to snow instability but in future work all relevant micrometeorological spatial interactions should be considered

estimating thermal conductivity in sedimentary basins using lithologic data and geophysical well logs a method for estimating in situ thermal conductivity profiles in oil and gas wells is advanced to rectify a major shortcoming in thermal analyses of sedimentary basins thermal conductivity estimates are made in a two stage procedure and are based on a model for the conductivity of mixtures and input data from lithological and geophysical logs first rock matrix conductivity for an arbitrary depth interval i e drill cuttings sample interval which is about 3 m is determined from the laboratory calibrated conductivities and volumetric representation of its individual lithologic components using a geometric mean model in situ conductivity is then estimated by a second application of the model correcting for temperature and porosity determined from geophysical logs the method is illustrated for three uinta basin utah wells that penetrate a series of tertiary sandstones shales and muddy carbonates detailed lithologic descriptions together with sonic and neutron logs were digitized and used for estimating in situ conductivity the validity of the method was tested by comparing the prediction against laboratory measurements on 565 samples from the same wells rock matrix thermal conductivity ranges from 1 6 to 6 8 w m k and is predicted within 20 of the actual measurement for 90 of the samples both in situ conductivity values and variations for a given lithologic unit are reduced at increased porosity and increased temperature thermal conductivity nomograms are presented as useful tools to predict directly the in situ thermal conductivit of a formation from a well log signal

elemental and sr nd isotopic compositional disparity of riverine sediments around the yellow sea constraints from grain size and chemical partitioning to obtain a better understanding of the source compositions of the river sediments around the yellow sea and their relationship with source rocks elements and strontium neodymium sr nd isotopes of different grain sizes silt and clay populations and chemical labile and residual phases fractionations in riverine sediments were studied extensively these results clearly revealed a systematic compositional disparity between korean river kr and chinese river cr sediments especially in the residual detrital fraction the geochemical dissimilarity between these might reflect inherited signatures of their source rocks but with minor control from chemical weathering in particular the remarkable enrichment of some elements iron fe and magnesium mg and the behavior of large ion lithophile elements e g barium ba potassium k and sr during weathering as well as less radiogenic sr isotopic compositions implies that cr sediments might be weathering products of relatively more mafic rocks with abundant ferromagnesian and plagioclase feldspar minerals compared with kr sediments derived from silicic granites with relatively higher quartz and potassium feldspar contents this different petrological rationale is clearly evident in an a cn k diagram which estimated the source rock of cr sediments as granodioritic a composition that reflects accurately the average composition of weathered continental crust in china the recognition of such geochemical systematics in two river sediments especially in grain size and chemically partitioned data may contribute to the establishment of provenance tracers for the yellow sea and east china sea sediments with multi sources as well the dust deposition in the western pacific c 2015 elsevier ltd all rights reserved

a review on the provenance discrimination of sediments in the yellow sea the yellow sea has been extensively studied for the understanding of dispersal patterns and limits of sediments from neighboring countries including china and korea although sedimentological mineralogical and geochemical approaches have been tried to solve the problems especially including the identification of sediment sources in and around the yellow sea the published results are not enough for understanding them suggestions on sediment origins budgets sediment accumulation rates mineralogical and geochemical compositions are not coincident to each other and sometimes even controversial for example conflicts on the distribution patterns of smectite and calcium carbonate the provenance of the southeastern yellow sea mud and sedimentation rates in there the ratios of v al and mn al in korea and china river sediments the origin of ba and pb in sandy sediments of the northeastern yellow sea and so on various geochemical indicators from the literature for the provenance discrimination in the yellow sea are reviewed here in depth and corresponding discussions are described separately research topics for the future study also are suggested for the proper access to the understanding of the origin and dispersal patterns of the yellow sea sediments especially focusing on the geochemical approaches d 2003 elsevier science b v all rights reserved

secondary grain size effects on li and cs concentrations and appropriate normalization procedures for coastal sediments the sediment grain size effect gse a fundamental factor relevant to the interpretation of elemental concentrations and isotopic compositions has been normalized using conservative elements such as aluminum al cesium cs and lithium li c al c cs c li which serve as proxies for the natural metal controlling variables of grain size mineralogy and organic matter however a secondary gse reportedly remains even after compensation by the al normalization procedure particularly for the concentrations of transition metals c t m this secondary effect also occurred in the c li c cs c al ratios of the korean coastal sediments examined in this study the primary and secondary gses on cs and li concentrations can be explained by the quartz dilution effect and the cs and li incorporation effect of phyllosilicate minerals respectively based on a model involving three component end members a cs and li free sand dominated sediment component consisting mostly of quartz and feldspar a cs and li bearing silt dominated component of mica and a cs and li enriched clay dominated component of illite although the primary and secondary gses on the concentrations of transition metals particularly cu and ni in coastal sediments might be normalized by dividing the metal concentrations by the square of the al concentration c t m c al 2 the gses can also be normalized by dividing the concentrations by the exact cs or li concentration c t m c cs c 2016 elsevier ltd all rights reserved

local to global controls on the deposition of organic rich muds across the late jurassic laurasian seaway muds deposited in large scale epicontinental seaways provide deep insights into palaeoclimates biogeochemical cycles sedimentation processes and organic carbon burial during exceptionally warm periods throughout the phanerozoic temporal changes can be monitored at single locations but the key larger scale oceanographical and related biogeochemical processes are likely to be more clearly revealed by comparisons between individual sub basins within seaways here we compare inorganic geochemical records from the jurassic upper pectinatites wheatleyensis to lower pectinatites pectinatus ammonite zones of the swanworth quarry 1 core from the wessex basin dorset uk to time equivalent records from the ebberston 87 core in the cleveland basin yorkshire uk 400 km apart our synthesis shows that while the dorset sediments were deposited in an energetically more dynamic setting than the yorkshire sediments the overarching climatic and oceanographical processes responsible for variations in organic carbon enrichment and sedimentation were similar intervals of coeval organic carbon rich sedimentation occurred in both basins and a particulate shuttle was intermittently active in both basins consistent with recent climate simulations we conclude that tropical climate conditions associated with enhanced nutrient supply were key drivers of sedimentation between the jurassic wessex and cleveland basins

overpressure retardation of organic matter maturation and petroleum generation a case study from the yinggehai and qiongdongnan basins south china sea three superimposed pressure systems developed in the yinggehai basin south china sea as indicated by seismic data well logs and direct pressure measurements the organic maturation profile is nonlinear with three nonparallel segments that correspond to the shallow normal pressured system the intermediate overpressured system and the deep strongly overpressured system respectively the intermediate and deep overpressured systems have abnormally low r0 gradients the organic maturity of these overpressured rocks is significantly lower than the maturity of normal pressured source rocks in nearby wells with similar thermal histories and does not match the thermal histories of the rocks such an organic maturity anomaly is distinctly different from those aused by variation in activation energies conductivity contrasts and hydrologic effects and is confirmed to be the result of overpressure retardation the degree to which the organic matter maturation is retarded expressed as the difference between predicted and measured vitrinite reflectance increases exponentially with increasing fluid pressure confirming that pressure increases the activation energies of organic matter maturation reactions overpressure retardation has been proven to be conditional and quite important for clearly understanding petroleum generation migration and accumulation in overpressured sedimentary basins

geochemistry and particle size of surface sediments of gulf of manfredonia southern adriatic sea abstract in this study we describe mechanisms influencing the spatial distribution of the surface sediments in the gulf of manfredonia seventy three samples were collected on a regional grid and analyzed for grain size major and trace elements and organic matter content sediments contain marine derived carbonate as well as terrigenous fractions indicating highly heterogeneous sediment composition dictated by different provenance and complex transport processes principal component analysis provides information about processes involved in the formation and dispersal of the sediments the regional sediment distribution is function of the gulf s morphology and sedimentary inputs from fluvial sources mainly from the ofanto river and from the north and central adriatic basin biogenic carbonate reefs identified in two restricted coastal areas add complexity to sediment shelf dispersal the north adriatic current flowing southward transports and deposits sediments from the northern basin in the offshore area of the gulf while an inner anticyclonic current distributes and mixes northern and fluvial sediment with a clockwise pattern in order to better assess the fluvial contribution also bedload samples from the main river debouching into the gulf were sampled enabling the identification of geochemical indexes to distinguish the role of both fluvial inputs and hydrodynamic processes affecting solid particles dispersion within the gulf this study provides a contribution to a qualitative estimate of the sediment supply entailed in the southwestern adriatic basin

sediment distribution dispersal and budget in the yellow sea abstract information on the surface sediment distribution in the yellow sea is newly compiled based on all available data produced by chinese and korean workers and is used to refine the dispersal patterns and budget of sediments derived from the adjoining landmass the central yellow sea is largely covered with fine grained sediments originating from the huanghe river 2 2 10 8 t yr about 20 of the total discharge thick sediment accumulation exceeding 5 mm yr occurs in the gulf of bohai and around the shandong peninsula about two thirds of the total huanghe river discharge the old huanghe delta suffers from reworking by strong tides and waves and forms a mud patch southwest of cheju island accumulation rate 2 10 7 t yr more than half of the sediments derived from the changjiang river are deposited along the coast of the east china sea the remainder accumulate on the inner shelf off the river mouth in the southeastern yellow sea the keum river dominates sediment discharge forming a holocene mud belt along the southwestern coast of korea accumulation rate 5 10 6 t yr turbid water plumes occur nearshore throughout the year and their suspended sediments are transported along the tip of the peninsula to the western coastal embayments in the south sea the nakdong river discharge of 1 10 7 t yr is responsible for the eastern nearshore mud of the south sea relict sands occur in the northern part of the yellow sea in the northern east china sea and in the korea strait

physical property variations related to seismic units in the offshore sediments of the heuksan mud belt southeastern yellow sea korea abstract sixteen piston core samples collected from the heuksan mud belt on the southeastern inner shelf of korea were analyzed to characterize sediment property and distribution in relation to interpreted seismic units the results from seven of 16 cores are presented in this study using core locations along a seismic track line variations in physical properties with depth gradually increased and or decreased depending on the characteristics of the specific property property patterns are primarily the result of dewatering caused by compaction and or consolidation significant variations in depth are due to differences in sediment texture in particular core p03 is largely composed of sandy sediments below 170 cm all core data come from three specific seismic units i iia and iib in descending order the seismic patterns that define these units are interpreted as related to the rate of sea level change during transgressions and depositional processes during the holocene regionally the variation of physical properties along the seismic profile is likely to reflect the relative characteristics of the seismic units unit i is characterized by low shear strength wet bulk density and high porosity unit iia appears to have higher shear strength than units i and iib unit iib shows high wet bulk density and velocity these observations suggest that the physical properties are mainly controlled by depositional processes related to sea level change clay fabric analysis that uses a scanning electron microscope for two core samples shows the change of particle arrangement due to compaction caused by overburden loading with burial depth in the upper part of the core edge to edge and edge to face contacts dominate in contrast face to face contact characterized by the well oriented arrangement of clay particles frequently occurs in the lower parts of the cores indicating sediment compaction or initial consolidation caused by overburden pressure

formation of immature asphalt from organic rich carbonate rocks i geochemical correlation abstract the formation of low maturity asphaltic oils immature asphalts from carbonate source rocks was investigated the senonian bituminous rocks sbr in israel are organic rich carbonate rocks that were deposited in a high productivity environment and they are part of a sedimentary sequence that also contains cherts and phosphorites the sbr were studied in different basins and the samples are from outcrops and three deep drillholes the bitumen contents of the rocks are exceptionally high up to 700 mg g c org and immature asphalts are found to be associated with them geochemical analysis indicates that the bitumens are indigenous to the host sbr and the associated asphalts are bitumens that have migrated a short distance with negligible chemical fractionation the high heteroatom content of the kerogens up to 30 in the sbr is suggested as a possible cause of the generation of asphaltic oils in an early stage of maturation

cyclicity in the egret member kimmeridgian oil source rock jeanne d arc basin offshore eastern canada the origin of the observed variability in lithology total organic carbon and petrophysical properties of the egret member source rock interval in the jeanne d arc basin offshore eastern canada is examined detailed analyses of petrophysical logs indicate that the egret member is cyclic three different orders of cycles recognizable on well logs occur in the egret member the large and medium scale cycles are correlatable among wells the estimated cyclicities of the large and medium scale cycles fall into the milankovitch like cycle bands suggesting that the depositional cycles are the product of orbitally forced sea level and climatic changes and implying that egret member deposition lasted at least 1 65 million years using chronological information drawn from sedimentary cycles both spatial and vertical temporal variations in sedimentation rate are examined for the member a correlation exists between low sedimentation rates and high total organic carbon values in this basin it is most probable that the organic rich layers were deposited during times of high sea level stands and warmer periods

distribution of suspended sediment in the korea strait and southeastern yellow sea onset of winter monsoons abstract high energy conditions in the yellow sea begin each year with the onset of monsoon winds in late october these transitional season surges of cold air initiate sediment resuspension vertical mixing of suspended sediments and a wind driven coastal current that flows to the south during the summer to winter transition suspended sediment concentrations in the southeastern yellow sea range from 5 100 mg l 1 at the surface and 5 500 mg l 1 at the bottom the highest concentrations occur off the southwest tip of the korean peninsula and the lowest occur in the central part of the korea strait the rate of transitional season destratification may depend on the timing and intensity of monsoonal surges whereas a late onset of monsoon winds allows waters to remain longer in their moderately stratified summer condition an early onset of monsoon winds tends to destratify the water column by mid november resulting in a nearly uniform high concentration of suspended sediments from surface to bottom the band of more turbid coastal water ends abruptly 25 50 km offshore as a turbidity front in waters 20 80 m deep a wind driven residual flow to the south appears to transport large volumes of this turbid water into the korea strait and perhaps as far as the sea of japan

assessing effective provenance methods for fluvial sediment in the south china sea sediment is delivered by the rivers of se asia to the south china sea where it provides an archive of continental environmental conditions since the eocene interpreting this archive is complicated because sediment may be derived from a number of unique sources and the rivers themselves have experienced headwater capture that also affects their composition a number of methods exist to constrain provenance but not all work well in this area anthropogenic impacts most notably agriculture mean that the modern rivers contain more weathered materials than they did up until about 3000 years ago the rivers have also changed their bulk chemistry and clay mineralogy in response to climate change so that these proxies as well as sr isotopes are generally unreliable provenance indicators nd isotopes resolve influx from luzon but many other sources in se asia have similar values and clear resolution of end members can be difficult instead thermochronology methods are best suited especially apatite fission track which shows more diversity in the sources than either u pb zircon or ar ar muscovite dating nonetheless even fission track is best used as part of a multiproxy approach if a robust quantitative budget is desired

rare earth element fractionations of the northwestern south china sea sediments and their implications for east asian monsoon reconstruction during the last 36 kyr abstract rare earth elements rees fractionations in siliciclastic marine sediments are related to the parent rock properties weathering degree grain size and heavy minerals the relations between marine sediment ree compositions and regional paleoclimate are not fully understood here the rees for detrital components of a core retrieved from the northwestern south china sea scs were measured results show the ree lree hree la yb n and light ree la sm n fractionation degrees have good responses to the regional paleoclimate over the past 36 kyr sea level played a key role in ree fractionations during 36 24 kyr bp manifesting as lower ree and lree fractionation degrees correspond to the decreased sea level the entire trends for lree hree la yb n and la sm n over the past 20 5 kyr are almost in phase with the regional east asian summer monsoon easm records because rees are mainly concentrated in heavy minerals the density difference of heavy minerals is probably the main controlling factor on ree fractionations clay minerals and feldspars released during the weathering process have a high content of light rees lrees in the warm wet periods holocene optimum and bolling allerod more precipitation promoted weathering and strengthened the estuarine hydrodynamic force which respectively resulted in high content of clay minerals and feldspars and high density heavy minerals e g monazite the process led to lree enrichment because the enriched minerals contain higher contents of the lrees in contrast the dry cold climate conditions during the periods heinrich 1 younger dryas and last glacial maximum resulted in the reversed ree fractionations as the weak hydrodynamic force can only carry the low density heavy minerals e g zircon that are enriched in hrees this model does not seem to apply to 36 24 kyr bp probably because of the re transport of ancient shelf sediments the study facilitates the understanding of ree application in paleoclimate reconstruction within slope sediments

a computer based system simulating snowpack structures as a tool for regional avalanche forecasting this paper describes the current state of a complete automatic system of three numerical models that simulate snow cover stratigraphy and avalanche risks for operational avalanche forecasting the first model safran estimates relevant meteorological parameters affecting snowpack evolution the second crocus is a snow numerical model which simulates the physical processes inside the snowpack and its stratigraphy the last model mepra is an expert system based on an assessment of snowpack stability it deduces natural and accidental avalanche risks to describe the great variability of the snowpack and the associated avalanche risks this automatic system simulates snow cover evolution and its stability for many typical slopes elevations and aspects representative of the different french massifs to achieve this result different kinds of validations have been carried out since winter 1981 they are mainly based on comparisons with different sets of measurements and on the opinion of users although the routinely obtained results do not yet take into account all small scale effects such as wind transport they have been considered as valuable information by avalanche forecasters since 1992 93 and used operationally since then

source rock evaluation by well log analysis lower toarcian hils syncline abstract the feasibility of conducting petroleum source rock evaluations from well log data was examined using three continuously cored sections immature mature and postmature stages of the lower toarcian posidonia shale northern germany logs depicting natural gamma emission k u th bulk density sonic travel time and resistivity were utilised as was the borehole televiewer for fracture control selected data from these logs were correlated with parameters of source richness hydrocarbon content and maturity the resulting three dimensional cross plot shows at a glance well by well comparison of facies maturity and hydrocarbon content a simple correlation between organic geochemical and petrophysical parameters is of course not perfect since log response is complex and affected by mineralogical and pore fluid properties of the rock as well as by organics however source rock characterization by wireline logging is still a fast and therefore economical method relative quick look comparisons from well to well are possible without calibration to core data and can easily be performed at once at the drill site the present application is limited to clastic source rocks in basins with simple geologic histories

geochemistry of sediments from the huaibei plain east china implications for provenance weathering and invasion of the yellow river into the huaihe river abstract the sediments of the huaibei plain in semi humid mid eastern china represent valuable geological records with respect to eolian fluvial interactions depositional environments and climate change in this region provenance and weathering conditions are often reconstructed using sedimentary geochemistry methods in this study an 8 m core from huainan and a set of loess samples from northern and southern china were analyzed for major trace and rare earth elements rees results were compared to determine the samples provenance the major trace rare earth elements contents and grain size distribution were found to fluctuate widely in the 2 8 m section of the huainan core and more narrowly closer to the surface 0 2 m this suggests a provenance shift at a depth of 2 m the tio 2 al 2 o 3 sio 2 al 2 o 3 th nb la nb values and ree patterns in the upper core 0 2 m are similar to those found in samples from the chinese loess plateau clp these results suggest that the clp in northern china is likely to be the primary origin of the upper part 0 2 m of the huainan core compared with clp samples the upper part of the huainan core exhibits lower k 2 o al 2 o 3 values and higher chemical alteration indices this is indicative of the material s substantial weathering during transportation and re deposition and implies that these sediments could reasonably be classified as typical recycled loess the sediments may have been transported from the clp to huainan as yellow river flood events probably during the last deglaciation 13 2 ka as a result of increased precipitation along with glacier and snow melt in the upper reaches of the yellow river catchment during this period this suggests that the yellow river may have migrated into the huaihe river catchment much earlier than the earliest historical records 361 bce suggest the implications of this would be profound with respect to chinese history

determination of organic matter content of appalachian devonian shales from gamma ray logs the organic matter content of the devonian shale of the appalachian basin is important for assessing the natural gas resources of these rocks and patterns of organic matter distribution convey information on sedimentary processes and depositional environment in most of the western part of the appalachian basin the organic matter content of the devonian shale can be estimated from gamma ray wire line logs using the equation phgro ggrb ggr 1 378a where phgro is the organic matter content of the shale fractional volume ggr the gamma ray intensity api units ggrb the gamma ray intensity if no organic matter is present api units and a the slope of the crossplot of gamma ray intensity and formation density api units g cm3 the quantities a and ggrb vary regionally and are mapped using data from gamma ray and formation density wire line logs organic matter contents estimated using this equation are compared with organic matter contents determined from direct laboratory analyses of organic carbon for 74 intervals of varying thickness from 12 widely separated wells the organic matter content of these intervals ranges from near zero to about 20 by volume excluding the cleveland member of the ohio shale and the lower part of the olentangy shale the distribution of the differences between volume percent organic matter content determined from core samples and estimated from gamma ray logs has a mean of 0 44 and a standard deviation of 1 98 which indicates that the accuracy of the gamma ray method is adequate for most geologic applications the gamma ray intensity of the cleveland member of the ohio shale and the lower pa t of the olentangy shale is anomalously low compared to other devonian shales of similar richness so that organic matter content computed for each of these units from gamma ray logs is likely to be too low wire line methods for estimating organic matter content have the advantages of economy readily available sources of data and continuous sampling of the vertically heterogenous shale section the gamma ray log in particular is commonly run in the devonian shale its response characteristics are well known and the cumulative pool of gamma ray logs forms a large and geographically broad data base the quantitative computation of organic matter content from gamma ray logs should be of practical value in studies of the appalachian devonian shale the general approach described here may also be applicable to other formations with physical and geochemical characteristics similar to the appalachian devonian shale

geochemical constraints on the provenance of surface sediments of radial sand ridges off the jiangsu coastal zone east china abstract the jiang harbor centered radial sand ranges rsrs off the jiangsu coast are the largest in the yellow sea however the provenance of the rsrs remains controversial in this study we compare major and trace element geochemistry together with grain size and main mineral composition in carbonate free sediments from rsrs and potential sources onshore and offshore rsr sediments have different grain size characteristics onshore rsr sediments have mean grain sizes of 2 tio 2 li and partly in cs zn and some high field strength elements y zr nb pb and th while depleted in other elements offshore rsr sediments are complicated in geochemical compositions some of them have very high contents of high field strength elements and others are similar to onshore rsr sediments onshore and offshore rsr sediments have different controlling factors of geochemical compositions onshore rsr sediments are influenced by clay size minerals whereas offshore sediments are controlled by heavy minerals the identification of zr nb and ti zr vs k rb shows that onshore and offshore rsrs seem to have similar sources their differences in grain size are a result of hydrodynamic sorting the identification of elemental ratios reveals that sources of rsr sediments are variable in space and time and the inputs of the chinese rivers especially the old yellow river and the yangtze river are still dominant but the effect of the korean field cannot be neglected our findings also demonstrate the potential of elemental ratios such as zr nb and k rb as tracer pairs for provenance of sediments in the yellow sea

inhomogeneous precipitation distribution and snow transport in steep terrain 1 the inhomogeneous snow distribution found in alpine terrain is the result of wind and precipitation interacting with the snow surface over topography we introduce and explain preferential deposition of precipitation as the deposition process without erosion of previously deposited snow and thus in absence of saltation a numerical model is developed describing the relevant processes of saltation suspension and preferential deposition the model uses high resolution wind fields calculated with a meteorological model arps the model is used to simulate a 120 h snow storm period over a steep alpine ridge for which snow distribution measurements are available the comparison to measurements shows that the model captures the larger scale snow distribution patterns and predicts the total additional lee slope loading well however the spatial resolution of 25 m is still insufficient to capture the smaller scale deposition features observed the model suggests that the snow distribution on the ridge scale is primarily caused by preferential deposition and that this result is not sensitive to model parameters such as turbulent diffusivity drift threshold or concentration in the saltation layer

dispersal of fine grained sediments in the southeastern yellow sea a steady state model a large portion of the yellow sea is floored by fine grained clastics derived largely from the hwangho and yangtze rivers in the southeastern yellow sea however coarse grained sediments prevail derived probably from the short and steep korean rivers farther east the coarse grained sediments contain substantial amounts of fine fractions near the keum estuary detrital clays such as kaolinite and chlorite are abundant in the free fractions and this trend extends for about 120 km both toward the northwest and the southwest illite appears to be dominant in the rest of the yellow sea the data suggest that the bulk of fine grained sediments in the southeastern yellow sea originates from the keum river the sediments are subsequently transported by prevailing nearshore currents both northwestward during summer and southwestward in winter the tidal currents may also play a role the close correspondance between the oceanographic data and the mineralogic evidence suggests that the dispersal of fine grained sediments in the southeastern yellow sea occurs largely under the steady state conditions

quantitative reconstruction of holocene sediment source variations in the yellow and northern east china seas and their forcings abstract sediment provenance in the yellow sea and northern east china seas yecss has long been a subject of interest but its quantification is still inconclusive here we present an improved al mg regression analysis by refining its methodological approach to strengthen quantification of sediment source to sink transports in the yecss with focus on its forcing mechanisms during the holocene our quantitative source estimates clearly depict a considerable supply of the chinese river cr sediments 50 to the southwestern korean coastal region and the korean river kr sediments 30 40 to the central yellow sea mud deposit which accounts for a good balance between the sediment supply and budget of the shelf deposit of particular note is an abrupt decline in the cr contributions around 124 e which indicates that the cr sediments do not directly reach the eastern part of the yellow sea blocked by a strong physical boundary further the observed variations in proportions between huanghe changjiang and korean river derived sediments over the last 15 kyr notably an abrupt increase of cr contribution since 7 ka followed by a sudden drop at 3 4 ka exhibit a good correspondence with other mineralogical proxy records these temporal provenance changes witnessed robust palaeoenvironmental signals which fit to major climatic and oceanographic events linked with sea level intensity of the kuroshio current inflow and the east asian monsoon this study improves understanding of what pathways and sinks exist within the yecs basin and how rates of sediment supply from adjacent rivers have changed over time

wavelet analysis of well logging data from oil source rock egret member offshore eastern canada wavelet analysis is a sensitive method for automatically detecting and distinguishing abrupt discontinuities i e faults unconformities cyclicity and gradual changes in sedimentation rate by transforming depth related sedimentary signals i e gamma rays into wavelengths at distinct depth intervals we used wavelet analysis for evaluation of the spatio temporal distribution of oil source rocks and for estimating accumulation rates in a sedimentary basin having high resolution the method was applied to 16 gamma ray logs from the jurassic egret member an oil source rock succession 55 m to 227 m in thickness offshore eastern canada dominant gamma ray cycles having wavelengths varying from 2 8 m western margin of the basin to 24 m eastern part of the basin have been detected by wavelet analysis the coincidence of the ratio of predominant gamma ray cycles with the ratio of milankovitch spectra about 400 100 40 20 k y suggests that climatic cycles are an important factor controlling sedimentary cyclicity in the egret member dominant wavelengths likely represent 100 k y eccentricity giving accumulation times of 1 9 m y for stratigraphically complete sections having 19 successive 2 8 m gamma ray cycles and giving accumulation times of 600 k y for incomplete successions having only 6 cycles up to four discontinuities occur in gamma ray log cyclicity and separate the egret member into subunits we interpret the discontinuities as unconformities or faults and as related to sediments having low petroleum potential the stratigraphic completeness of the egret member is correlated to total mass of organic carbon and decreasing thickness of non source rock intervals having correlation coefficients of r 0 8 and r 0 76 respectively

physical and geotechnical properties of drill core sediments in the heuksan mud belt off sw korea abstract three drill core samples collected from the heuksan mud belt off sw korea have been used to characterize sediment properties in relation to seismic units and to interpret geotechnical properties as a function of burial depth the physical property data were readily classified into seismic units unit i subunit ii a subunit ii b subunit iii a subunit iii b and pre lgm last glacial maximum in descending order thus the variations in physical properties reflect the relative characteristics of the seismic units moreover the relationships between physical properties are well grouped by each seismic unit these results suggest that the physical properties of these sediments are mainly controlled by depositional processes related to sea level change as one of dominant sedimentary processes in the study area interestingly the shear strength and velocity of subunit ii b are characterized by cyclic variation these characteristic patterns are likely related to periodic variation in sedimentary environments e g wave or tide dominated environments in the study area clay fabric investigations with depth using scanning electron microscopy are characterized by different clay particle arrangements e g from edge to edge to face to face contact with depth owing to compaction effect caused by overburden pressure with depth the geotechnical properties of the heuksan mud belt suggest that the shallow regions are apparently over consolidated probably due to the flocculated fabrics at shallow depths and that the regions have moderate compressibilities in spite of the high mud content in the sediments

circum arctic petroleum systems identified using decision tree chemometrics source and age related biomarker and isotopic data were measured for more than 1000 crude oil samples from wells and seeps collected above approximately 55n latitude a unique multitiered chemometric multivariate statistical decision tree was created that allowed automated classification of 31 genetically distinct circum arctic oil families based on a training set of 622 oil samples the method which we call decision tree chemometrics uses principal components analysis and multiple tiers of k nearest neighbor and simca soft independent modeling of class analogy models to classify and assign confidence limits for newly acquired oil samples and source rock extracts geochemical data for each oil sample were also used to infer the age lithology organic matter input depositional environment and identity of its source rock these results demonstrate the value of large petroleum databases where all samples were analyzed using the same procedures and instrumentation

relation between source rock properties and wireline log parameters an example from lower jurassic posidonia shale nw germany abstract the relationships between source rock quality and wireline log parameters were established for the lower jurassic posidonia shale the most prolific petroleum source rock of central europe wireline logs used are the gamma ray spectrometry density sonic and various resistivity logs the organic geochemical parameters considered include the organic carbon content hydrogen index and the hydrocarbon potential expressed by pyrolysis yield the case history presented is based on a continuous core through the entire posidonia shale interval from a location where this source rock is immature care was taken to detect and to avoid samples and log values influenced by bore hole roughness and fractures fair correlations were observed only between uranium content from gamma ray spectrometry log and organic carbon content no correlation was recognized between uranium content and kerogen type as defined by hydrogen indices for various reasons density sonic and resistivity logs did not provide useful data in this study three rock units with irregular high and low uranium contents could be differentiated possible causes for this tripartition are different environments during deposition and postdepositional redistribution of uranium during early diagenesis and in association with fractures

artificial neural network modelling as an aid to source rock characterization abstract a data based approach is used to establish detailed and accurate geochemical characterization in oil source rock intervals using well logs and noisy information from cuttings the method starts by extracting examples from the intervals of interest using generalized relationships between total organic content toc and well log responses the examples were used to train an artificial neural network ann that extracted more detailed and accurate relationships between toc and well log responses specific to the study area a combination of the quickprop algorithm and dynamic node creation scheme was utilized to facilitate efficient training the trained ann is useful for mapping source rock intervals in the area of interest this method performs satisfactorily when applied to the egret source rock of the jeanne d arc basin offshore eastern canada

predicted and measured petrophysical and geochemical characteristics of the egret member oil source rock jeanne d arc basin offshore eastern canada abstract the log r wireline log technique has been used to predict high vertical resolution geochemical profiles for 17 well penetrations of the upper jurassic egret member source rock of the jeanne d arc basin offshore newfoundland the predictions are compared with rock eval data obtained from the same interval high resolution comparison of the computed total organic carbon toc curves with gamma ray logs implies that the source rock layers in the egret member are mainly shale claystone and the non source rock layers are limestone marl to the south and siltstone sandstone to the north these comparisons also indicate that in the mature area some coarse grained non source rock layers are filled with hydrocarbons implying primary migration of oil gas using the average computed toc value the thickness of the egret member and the average formation density the mass of organic carbon was calculated at 19 well locations and regional variations examined areas with a great mass of organic carbon were identified the present mass of organic carbon is primarily related to the amount of organic matter being deposited and preserved but the expulsion of oil gas may also exert a control using 1 wt as the lower limit for a source rock it was observed that the percentage of non source rock in the egret member is generally higher in immature wells lom 7 than in mature wells probably as a result of hydrocarbon migration expulsion after maturation

determination of the total organic carbon toc based on conventional well logs using artificial neural network abstract total organic carbon toc is the measure of the amount of carbon available in an organic compound and is often used as an essential factor for unconventional shale resources evaluation previous models for toc determination based on density log data considered the presence of organic matter is proportional to the formation bulk density also model those based on resistivity log sonic or density logs as well as the formation level of maturity lom were used to determine the toc these models assumed linear relation between resistivity and porosity logs previous correlations showed very low coefficient of determination of the estimated toc compared to the actual laboratory data the objective of this paper is to develop an empirical correlation to determine the toc for barnett and devonian shale formations based on conventional logs using artificial neural network ann core toc data 442 data points and well logs resistivity gamma ray sonic transit time and bulk density from barnett shale were used to develop the ann model for the first time an empirical correlation for toc was developed based on the weights and biases of the ann model the developed correlation was then applied to estimate toc for devonian shale the developed ann model predicted the toc based on conventional well log data with high accuracy the average absolute deviation aad and coefficient of determination r2 for the predicted toc compared with the measured toc for barnett shale are 0 91 wt and 0 93 respectively the developed model outperformed the previous available models in estimating toc for devonian shale as well with aad of 0 99 wt and r2 of 0 89 compared to aad of 1 16 wt or more and r2 of 0 65 or less for the available correlations the developed empirical correlation was used to estimate the toc with high accuracy for barnett shale and devonian shale formations the developed correlation will help the geological and reservoir engineers predict the toc using well logs without the need to measure toc in the laboratory

borehole petrophysical chemostratigraphy of pennsylvanian black shales in the kansas subsurface pennsylvanian black shales in kansas have been studied on outcrop for decades as the core unit of the classic midcontinent cyclothem these shales appear to be highstand condensed sections in the sequence stratigraphic paradigm nuclear log suites provide several petrophysical measurements of rock chemistry that are a useful data source for chemostratigraphic studies of pennsylvanian black shales in the subsurface spectral gamma ray logs partition natural radioactivity between contributions by u th and k sources elevated u contents in black shales can be related to reducing depositional environments whereas the k and th contents are indicators of clay mineral abundance and composition the photoelectric factor log measurement is a direct function of aggregate atomic number and so is affected by clay mineral volume clay mineral iron content and other black shale compositional elements neutron porosity curves are primarily a response to hydrogen content although good quality logs are available for many black shales borehole washout features invalidate readings from the nuclear contact devices whereas black shales thinner than tool resolution will be averaged with adjacent beds statistical analysis of nuclear log data between black shales in successive cyclothems allows systematic patterns of their chemical and petrophysical properties to be discriminated in both space and time

the northern gulf of mexico during oae2 and the relationship between water depth and black shale development despite their name oceanic anoxic events oaes are not periods of uniform anoxia and black shale deposition in ancient oceans shelf environments account for the majority of productivity and organic carbon burial in the modern ocean and this was likely true in the cretaceous as well however it is unlikely that the mechanisms for such an increase were uniform across all shelf environments some like the northwest margin of africa were characterized by strong upwelling but what might drive enhanced productivity on shelves not geographically suited for upwelling to address this we use micropaleontology carbon isotopes and sedimentology to present the first record of oceanic anoxic event 2 oae2 from the northern gulf of mexico shelf here oae2 occurred during the deposition of the well oxygenated inner neritic lower estuarine lower tuscaloosa sandstone the overlying organic rich oxygen poor marine tuscaloosa shale is entirely turonian in age we trace organic matter enrichment from the spinks core into the deepwater gulf of mexico where wireline log calculations and public geochemical data indicate organic enrichment and anoxia throughout the cenomanian turonian boundary interval redox change and organic matter preservation across the gulf of mexico shelf were driven by sea level rise prior to the early turonian highstand which caused the advection of nutrient rich oxygen poor waters onto the shelf this results in organic matter mass accumulation rates 1 2 orders of magnitude lower than upwelling sites like the nw african margin but it likely occurred over a much larger geographic area suggesting that sea level rise was an important component of the overall increase in carbon burial during oae2

evolution of late quaternary mud deposits and recent sediment budget in the southeastern yellow sea abstract analysis of high resolution seismic reflection profiles and sediment samples has revealed the evolution and sediment budget of the southeastern yellow sea mud belt seysm along the southwestern korean peninsula the seysm up to 50 m thick over 250 km long and 20 55 km wide can be divided into three stratigraphic units a1 a2 and b from oldest to youngest unit a1 overlying the acoustic basement comprises the northern part of the seysm unit a2 comprises the southern part of the seysm much of unit a2 is exposed at the seafloor unit b completely covers unit a1 and pinches out southward 14c data suggest that evolution of each unit is closely related to the postglacial sea level changes unit a1 consists of estuarine deltaic or shallow water muds deposited during the early to middle stage of postglacial sea level rise ca 14 000 7000 yr b p unit a2 corresponds to relict muds deposited during the last deceleration stage of sea level rise ca 7000 3 500 yr b p unit b consists of shelf muds deposited during the recent sea level highstand ca very low background activities of 210pb of the surface sediment of unit a2 suggest that the present day sediment accumulation is negligible in the southern seysm on the other hand 210pb excess activity profiles in unit b yield an average sediment accumulation rate of 3 9 mm yr indicating active sediment accumulation in the northern seysm the annual sink 3 0 10 7 tons yr of fine grained sediment in unit b is about an order of magnitude greater than can be explained by the sediment input from the korean rivers alone we propose that reworking of unit a2 has provided large volumes of muds to unit b resulting in excessive sediment accumulation in the northern seysm much of unit a2 in turn is likely to have originated from erosion of unit a1 in the north this rather unique erosional depositional regime of the seysm is probably owing to the tidal and regional currents characteristic in the southeastern yellow sea

statistical forecasting of regional avalanche danger using simulated snow cover data in the past numerical prediction of regional avalanche danger using statistical methods with meteorological input variables has shown insufficiently accurate results possibly due to the lack of snow stratigraphy data detailed snow cover data were rarely used because they were not readily available manual observations with the development and increasing use of snow cover models this deficiency can now be rectified and model output can be used as input for forecasting models we used the output of the physically based snow cover model snowpack combined with meteorological variables to investigate and establish a link to regional avalanche danger snow stratigraphy was simulated for the location of an automatic weather station near davos switzerland over nine winters only dry snow situations were considered a variety of selection algorithms was used to identify the most important simulated snow variables data mining and statistical methods including classification trees artificial neural networks support vector machines hidden markov models and nearest neighbour methods were trained on the forecasted regional avalanche danger european avalanche danger scale the best results were achieved with a nearest neighbour method which used the avalanche danger level of the previous day as additional input a cross validated accuracy hit rate of 73 was obtained this study suggests that modelled snow stratigraphy variables as provided by snowpack are able to improve numerical avalanche forecasting

geochemistry of alkaline earth elements mg ca sr ba in the surface sediments of the yellow sea abstract the concentrations of alkaline earth elements were measured in the surface sediments of the yellow sea in an attempt to establish their sources from horizontal distributions the maximum concentrations of mg are found in the central yellow sea and its horizontal distribution is mainly controlled by quartz dilution the concentrations of ca and sr increase toward the southeastern yellow sea region the relatively higher enrichment of ca and sr in the southeastern yellow sea with sr ca ratios of 0 0053 suggests the presence of carbonates which are comprised of foraminifera and or coccoliths like deep sea carbonates on the other hand the concentrations of ba increase toward the northeastern yellow sea the higher ba enrichment in the sandy region of the northeastern yellow sea is associated with the presence of feldspar as evidenced by excellent correlations among ba mg al mg and sr ca ratios our results suggest that the transgressive and relict sand occurring in the eastern parts of the yellow sea contains al sr and ba enriched feldspars which originated from arprock river korea and thus can be distinguished from sand occurring in the western parts of the yellow sea which originated from yellow and yangtze rivers

a dual porosity model for evaluating petroleum resource potential in unconventional tight shale plays with application to utica shale quebec canada unconventional tight to shale reservoirs vary from tight sandstone siltstone to organic rich mudstone shale commonly with mixed lithologies in such reservoir systems matrix pores and organic pores with different origins and distinct physical and chemical properties co exist for hydrocarbon storage traditional resource assessment methods designed for conventional reservoirs cannot handle the two pore systems properly this study proposes a dual porosity model to respond to the need for a new method in assessing hydrocarbon resource potential in such reservoir systems the dual porosity model treats the two types of pores separately and derives the resource estimates from different sources of data thus better characterizing unconventional reservoirs with complicated pore systems the new method also has the flexibility of assessing resource potential for the entire spectrum of mixed lithologies ranging from a complete tight to a pure source rock organic rich shale mudstone reservoir the proposed method is illustrated through the assessment of the in place petroleum resource potential in the upper ordovician utica shale of southern quebec canada the results of the application suggest that the proposed approach effectively handles the two pore systems in tight shale reservoirs effectively and provides a useful tool for estimating resource potential in unconventional plays

sediment accumulation in a modern epicontinental shelf setting the yellow sea sediment accumulation in the yellow sea epicontinental shelf environment is investigated on 100 yr and 1000 yr time scales using 210pb and 14c geochronologies the distribution of modern 210pb accumulation rates in the yellow sea reveals that the loci of modern huanghe sediment accumulation are the topset 1 2 mm yr foreset 4 9 mm yr and proximal bottomset deposits 2 4 mm yr of the shandong subaqueous delta which extends south from the shandong peninsula 210pb rates in the distal bottomset deposits of the subaqueous delta in the central and southern yellow sea are generally low 0 3 0 9 mm yr a sediment budget demonstrates that between 9 15 of the annual huanghe discharge is accumulating in the yellow sea about two thirds of this sediment is accumulating in the topset foreset and proximal bottomset deposits of the shandong subaqueous delta with the remaining third accumulating as widespread distal bottomset deposits 14c age dates of subaqueous delta sediments indicate that the thick 40m clinoform structure formed predominantly between 6200 and 4060 yrs b p at rates approaching 20 mm yr observations in the yellow sea as well as on the amazon and ganges brahmaputra shelves demonstrate that subaqueous deltaic stratigraphy is the general rule where major rivers enter energetic shelves whether epicontinental or pericontinental the development of extensive bottomset deposits may be restricted to epicontinental shelf environments and may be diagnostic of sedimentation in this type of setting

geochemical variability induced by entrainment sorting quantified signals for provenance analysis abstract a substantial part of the mineralogical and chemical heterogeneity of clay poor sands at the bed scale results from tractive redistribution of the grains in the bedload since coarse and light particles are more easily entrained than denser and smaller heavy minerals the latter commonly concentrate in grain scale lags that alternate with sand depleted in these minerals when sampled and analysed at the centimetre scale this primary heterogeneity translates into nice geochemical covariations between the minor trace elements that concentrate in some heavy minerals zr ti p cr v y ce among others regressing these variations allow us to derive two chemical fingerprints of the sand one records the proportions between some heavy minerals the other the average composition of framework grains i e a sand composition corrected from the contribution of heavy minerals both relate to provenance and allow different sand beds to be compared in appropriate spider diagrams the construction of these diagrams their potential use and their limitations are discussed using two contrasting examples continental channel sandstones from the ravenscar group middle jurassic yorkshire uk illustrate how these geochemical fingerprints vary from the local to the group scales and how robust they are against diagenetic overprint at ravenscar the zr vs ti v cr covariations record the presence of ti oxides and magnetite together with zircon and of volcanic lithoclasts at the deposition stage despite a high degree of diagenetic alteration overbank sandstones lateral to channels from the deep marine gres d annot formation eocene oligocene alps illustrates how apatite and monazite delivered by a dominantly granitic source generate covariations between zr and p y ce and th contents with characteristically steep slopes

a practical model for organic richness from porosity and resistivity logs a practical method the delta log r technique for identifying and calculating total organic carbon in organic rich rocks has been developed using well logs the method employs the overlaying of a properly scaled porosity log generally the sonic transit time curve on a resistivity curve preferably from a deep reading tool in water saturated organic lean rocks the two curves parallel each other and can be overlain since both curves respond to variations in formation porosity however in either hydrocarbon reservoir rocks or organic rich non reservoir rocks a separation between the curves occurs using the gamma ray curve reservoir intervals can be identified and eliminated from the analysis the separation in organic rich intervals results from two effects the orosity curve responds to the presence of low density low velocity kerogen and the resistivity curve responds to the formation fluid in an immature organic rich rock where no hydrocarbons have been generated the observed curve separation is due solely to the porosity curve response in mature source rocks in addition to the porosity curve response the resistivity increases because of the presence of generated hydrocarbons the magnitude of the curve separation in non reservoirs is calibrated to total organic carbon and maturity and allows for depth profiling of organic richness in the absence of sample data this method allows organic richness to be accurately assessed in a wide variety of lithologies and maturities using common well logs

development of depositional systems in the southeastern yellow sea during the postglacial transgression this study focuses on the development of depositional systems in the southeastern yellow sea during the postglacial transgression based on the analysis of closely spaced high resolution seismic profiles chirp and piston cores transgressive deposits comprise the paralic component of estuarine channel fills seaward prograding wedge and along shore prograding mound and the marine component of sand veneer mud blanket and offshore ridge these transgressive deposits were developed through three distinctive stages in terms of possible sea level position during the early stage tidal sand ridges and sand veneer formed south of jeju island resulting from shoreface erosion associated with a relatively slow transgression the following transgression in the middle stage inundated subaerially formed interfluves along the central part of the sea and affected development of estuarine environments with increasing tidal regime in the eastern part of the sea combined with the strong tidal reworking insufficient sand supply enhanced the formation of erosional ridges short period increase in fluvial discharge affected the deposition of coastal wedge in the western part fine grained sediments from either fluvial discharge or tidal reworking were dispersed seaward to form mud blanket the late stage was characterized by the deposition of veneered sands off the jiangsu coast which was due to relatively slow rise in sea level further offshore along shore prograding mound was constructed by huanghe derived sediment influx and subsequently eroded and redeposited by wave and tide activities thus detached from the proximal source the depositional processes and variability of the transgressive deposits in the southeastern yellow sea were largely controlled by changes in rate of sea level rise during the transgression most likely related to the global flooding events triggered by melt water pulses the changes in shoreline configuration and oceanographic regime have also influenced the distribution and morphology of the transgressive deposits a short period increase in riverine discharge caused the temporal sediment progradation off the jiangsu coast

ree partitioning in riverine sediments around the yellow sea and its importance in shelf sediment provenance abstract we sought to identify the characteristics and their controlling factors of rare earth element ree fractionation patterns in two chemically partitioned labile and residual fractions of korean kr and chinese riverine cr sediments we also investigated their sediment origins in the yellow sea based on ree signatures the results showed that the upper continental crust ucc normalized ree fractionation patterns were remarkably different for labile and residual fractions even between kr and cr sediments notably kr sediments in both residual and labile fractions exhibited a striking enrichment of light rees lrees unlike cr sediments with no obvious fractionation such lree enrichment is relatively much stronger in the coarse grained sandy sediments the peculiar lree enrichment in both fractions of kr sediments was preferentially linked to grater felsic granitic compositions compared with cr sediments that were close to those of the ucc granodiorite with relatively more mafic minerals consisting of a mixture of various rock types application of these ree signatures to the provenance of yellow sea sediments provides an important clue to the cause underlying the lack of correlation between the mud budget and the river discharge in korean coastal regions as well as the ultimate fate of cr sediments the ree fractionation signals especially in residual fractions may shed light on the major existing phases affecting ree fractionation as well as the origin of sediments in the yellow sea

stratigraphic and geochemical investigation of kukersites petroleum source beds within the ordovician red river formation williston basin abstract the upper ordovician red river formation has been a prolific producer of oil and gas in the williston basin where it has cumulatively produced more than 750 million bbl of oil equivalent over the past half century previous studies have recognized petroleum source beds referred to as kukersites in the red river formation but have not determined their complete extent or hydrocarbon generation significance examination and analysis of 28 cores and greater than 300 wireline logs have revealed 10 distinct kukersites in the red river d zone that can be correlated individually for tens to hundreds of miles tens to hundreds of kilometers across the western quarter of north dakota although each red river kukersite is typically thin 1 2 ft 0 3 0 7 m thick they combine to reach net thicknesses of greater than 12 ft 3 7 m with average present day total organic carbon toc values of typically 3 6 wt hydrogen index hi values from kukersite samples range from primarily greater than 800 mg hydrocarbons hc g toc within the northern flank of the basin to systematically decreasing to less than 100 mg hc g toc within the basin center this systematic decrease in hi is interpreted to be a function of increased thermal maturity where hydrocarbon generation has depleted kukersite organic richness preliminary calculations of hydrocarbon volumes generated from red river kukersites based on a previously developed method that calculates the volumetric decrease in original to present day kerogen content total approximately 66 billion bbl 1 05 10 10 m 3 of oil equivalent this approximate generation total is more than enough to account for cumulative red river production and supports the idea that the red river is a self sourced petroleum system with potentially significant remaining exploration potential

organic carbon in bakken formation united states portion of williston basin the upper and lower members of the mississippian and devonian bakken formation in the united states portion of the williston basin are black shales that are extremely rich in organic matter and are the source of much of the oil found in the basin organic carbon values are calculated from formation density logs using the equation toc 154 497 rgr 57 261 where toc is organic carbon content wt and rgr is formation density g cm3 test calculations comparing this equation to laboratory organic carbon analyses from 39 wells in north dakota show an average absolute difference of 1 1 in organic carbon content organic carbon content calculated at 159 locations in north dakota and 107 in montana averages 12 1 for the upper member of the bakken formation and 11 5 for the lower member there is a regional depletion of organic carbon paralleling present day isotherms that reflects the conversion of organic matter to oil and subsequent expulsion of the oil from the formation the mass of organic carbon in the bakken formation is approximately evenly divided between the upper and lower members and it totals about 126 1012 kg in the study area of which 102 1012 kg are in the thermally mature region the assumption that 167 mg hc g toc have migrated out of the mature bakken shales leads to a tentative estimate that hydrocarbons equivalent to 132 billion bbl of 43 api gravity oil have been expelled from the united states portion of the upper and lower members of the bakken formation

customized interpretation workflow for simultaneous assessment of unconventional shale gas reservoirs and conventional reservoirs using seismic and log data the same geophysical and geologic data have been interpreted for both unconventional shale gas and conventional sandstone reservoirs simultaneously by framing and using a customized workflow customization was needed because of property differences between the two types of resources unconventional shale reservoirs differ significantly from conventional reservoirs in depositional environment diagenesis physical properties and production techniques magnitudes and patterns of reservoir properties e g velocity resistivity radioactivity porosity permeability etc of shales differ significantly from those of sandstone carbonate reservoirs in a conventional play we generally search for intervals with relatively low gamma high resistivity and low neutron porosity whereas in shale gas we search for intervals with very high gamma relatively higher resistivity than lean shales low velocity and very high neutron porosity production from shales is largely due to horizontal drilling hydrofractur

identification of source rocks on wireline logs by density resistivity and sonic transit time resistivity crossplots source rock formations generally show a lower density a lower sonic transit time and a higher resistivity than other sediments of equal compaction and comparable mineralogy this phenomenon can be used to identify source rocks on wireline logs provided the source rocks have a minimum thickness within the resolution of the sondes used and are sufficiently rich in organic matter classification rules have been established to assist in the recognition of source rocks on a combination of logs because of the low density contrast between water and organic matter the method becomes inaccurate at high water saturations i e low compaction within limits the amount of organic matter contained in a sediment can be estimated from log anomalies when source rocks become mature free oil is present in addition to kerogen and the resistivity increases by a factor of 10 or more

geochemistry of surface sediments off the southern and western coasts of korea abstract the continental shelf off the southern and western side of the korean peninsula is part of a modern epicontinental sea and is an effective sediment trap for clastic material derived from china and korea we have analyzed 179 surface sediment samples from this shelf for al fe na k mg ca ti p mn sr ba v cr co ni cu zn organic carbon and calcium carbonate in order to determine the geochemical characteristics of these sediments results showed a wide range of element contents which are mainly related to the textural variability of sediments exceptions to this were found in the contents of ca k sr and ba the ca and sr contents were largely determined by the amounts of carbonate present the k content on the other hand appeared to be influenced by both the contents of illite and feldspar and ba of potassium feldspar for muds i e sediments deposited under present day conditions it is possible to distinguish those in the central yellow sea from those in the keum estuary the former are characterized by high contents of fe na k mg ca and v and the latter by high contents of mn ba and co these differences become more apparent when these elements are normalized relative to al in order to minimize grain size effects the distribution of v al ratios is different from that of other elements the highest v al values occur in muds from the central yellow sea derived from the huanghe the yellow river in china whereas the highest values of mn al are found in the nearshore area adjacent to the korean peninsula based on these results it is suggested that the sources of fine sediments in the yellow and south seas can be distinguished from the geochemical characteristics of the surface sediments in the yellow sea two different sources of fine grained sediments can be seen the huanghe and the keum river the former is characterized by higher v contents and the latter by higher mn contents using the v al ratio as an end member component of the two source materials the dispersal patterns of the fine sediments 6o were also derived

sediment pathway of the east china sea inferred from an r mode factor analysis of surface sediments in the okinawa trough major and trace elements loss on ignition loi and grain size distributions were determined on 190 surface sediment samples collected from the continental shelf slope and the north okinawa trough in the east china sea at water depths of 100 200 200 600 and more than 600 m respectively the sediments are composed mainly of sand and silt generally low clay contents average 10 5 increasing over the range of 0 12 53 6 from the shelf and slope to the trough sediments were sandier on the continental shelf particularly in the northern shelf sector spatial distributions in chemical compositions show that the contents of sio 2 cao sr and loi values were relatively high on the sandy continental shelf by contrast the contents of al 2 o 3 mgo na 2 o mno feo tio 2 cu zn co ni and cr were relatively high in the trough and along the central western shelf margin where the sediments were composed mainly of silt fe 2 o 3 p 2 o 5 and zr enrichment was highest in the slope sediments three factors were extracted by means of an r mode factor analysis of chemical composition factor 1 has two inversely correlated elemental assemblages 1 sio 2 k 2 o tio 2 al 2 o 3 and zr which can be associated with terrigenous debris input and show high positive factor scores in the southern sector of the shelf and 2 cao sr and loi which can be related with biogenic debris enrichment and show high negative factor scores in the northern shelf sector as well as in a more restricted area along the slope cao sio 2 k 2 o and sr represent the element assemblage of the shelf factor 2 comprises na 2 o feo al 2 o 3 tio 2 cu zn and ni and shows high scores in the trough sediments na 2 o cu zn and ni represent the elemental assemblage of the okinawa trough and can be associated with volcanic matter factor 3 comprises fe 2 o 3 mgo cr and co with high factor scores on the slope and along the central western shelf margin of the study area due to upwelling induced enrichments in nutrients and biogenic shells fe 2 o 3 and mgo are the slope elements based on the results of the distribution of the chemical compositions and the elemental assemblage of the surface sediment in the source to sink system the influence of the yellow river on the continental shelf is stronger than that of the yangtze river from the continental shelf and slope to the trough the influence of the yellow river decreased from north to south in the okinawa trough the sediment from the yellow river decreases and from the yangtze river increases and the chemical compositions changed c 2009 elsevier ltd and inqua all rights reserved

origin and dispersal of recent clay minerals in the yellow sea abstract the clay minerals in the by considering the clay minerals supplied by rivers in china the old and present day huanghe river and korea the keum and yeongsan to the yellow sea continental shelf and the spatial variation in the distribution of clay minerals in the yellow sea this study indicates that the provenance of the cysm may be closely related to the old and present day huanghe river system whereas the clay minerals in the seysm seem to be largely associated with the keum and yeongsan rivers in addition smectite may be suggested as an important clay mineral in differentiating between cysm and seysm and understanding the sources of these two mud categories

the rare earth element compositions of the changjiang yangtze and huanghe yellow river sediments thirty four samples from the changjiang and huanghe were analyzed to characterize their rare earth element ree compositions although ree concentrations in the changjiang sediments are higher than those of the huanghe sediments the former are less variable bulk samples and acid leachable fractions have convex ree patterns and middle ree enrichments relative to upper continental crust whereas flat patterns are present in the residual fractions source rock composition is the primary control on ree composition and weathering processes play a minor role grain size exerts some influence on ree composition as demonstrated by the higher ree contents of clay minerals in sediments from both rivers heavy minerals contribute about 10 20 of the total ree in the sediments apatite is rare in the river sediments and contributes less than 2 of the ree content but other heavy minerals such as sphene allanite and zircon are important reservoirs of residual ree fractions the fe mn oxides phase accounts for about 14 of bulk ree content in the changjiang sediments which could be one of the more important factors controlling ree fractionation in the leachable fraction 6 2002 elsevier science b v all rights reserved

origin of inner shelf mud deposit in the southeastern yellow sea huksan mud belt abstract a variety of previous sedimentological results together with newly obtained hydrodynamic data are summarized and reinterpreted with respect to the most likely origin of the huksan mud belt hmb in the southeastern yellow sea the hmb consists of two mud units that have similar grain texture and clay mineralogy but can be differentiated on seismic profiles because the lower unit is generally harder than the watery upper unit the hydrographic measurements together with satellite imagery clearly indicate that the suspended plume covering the hmb originates from the west coast of korea the suspended plume becomes enhanced by winter monsoon winds beginning in late fall most of the studies of clay mineralogy geochemistry and isotherm distribution also suggest that the hmb has been derived from the west coast of korea particularly from the keum river an approximate evaluation of the depositional time for the hmb based on its dimensions and the discharge rate of the keum river suggests a time duration of the order of 14 000 years hydrodynamic measurements across two transects over the northernmost hmb reveal that suspended matter travels southwest toward the main body of the hmb in a well constrained corridor ultimately connected with the keum river time series 12 5 h hydrodynamic measurements at a site over the hmb suggest that the winter season suspended plume carries concentrations of suspended matter one to two orders of magnitude higher than those of the summer silt grains of 5 6 well sorted through numerous resuspension events settle out onto the hmb forming distinctive silt laminae alternating with clay rich laminae

methods for source rock identification on seismic data an example from the tanezzuft formation tunisia abstract source rocks occurrence extension and quality in the subsurface are usually characterized directly from well data seismic characterization is however becoming an emerging technique for extending source rock properties beyond well locations and an effective tool for mapping their lateral and vertical heterogeneities the tanezzuft formation in tunisia an extremely organic rich source rock was used as a test for applying and comparing different seismic methods aimed at organic rich sequences characterization the data used consist of a 2d seismic line shot in the northern flank of the ghadames basin tunisia pre stack gathers extracted from an inline of a 3d survey and four wells with a complete set of wireline and petrophysical logs impedance inversion avo and seismic attributes were computed on the seismic lines and compared to well data impedance inversion together with a rock physics model of the formation generated a quantitative estimate of total organic carbon toc content in the studied 2d seismic line avo analysis showed a class iv and a base class iv response for the upper and lower reflectors delimiting the organic rich interval respectively seismic attributes analyzed the formation by exploiting its high impedance contrast and intrinsic anelastic attenuation the three methods here discussed showed coherent results both when compared each other and when compared with the well data and the regional geological model in particular avo and seismic attribute analysis are methods that can be applied without the need of well information and are then feasible methods for the investigation of source rock properties in undrilled basins

discrimination of sediment provenance in the yellow sea secondary grain size effect and ree proxy this study analyzed grain size and elemental concentrations al mg fe and rare earth elements rees in 91 surface sediments to elucidate sediment provenance in the yellow sea elemental concentrations were normalized by al concentration c element c al to minimize the sediment grain size effect gse however noticeable linear relationships between ai concentration or mean grain size and the ratio e g mg al or fe al appeared unexpectedly in pair diagrams the spatial distribution patterns of fe al and mg al ratios were also similar to the pattern of mean grain size this implies that the gse was not removed completely even after the normalization process thus great care must be taken when applying the ratios of c element c al as a proxy of sediment provenance to improve provenance discrimination of the sediments in the yellow sea the difference between the ree distribution patterns of chinese and korean river sediments expressed as delta delta ree la ree lu was calculated and the spatial distribution patterns of the delta values were mapped the delta values gradually increased from the western to the eastern part of the yellow sea except for low delta values in the southeastern part of the yellow sea this result indicates that the majority of chinese and korean river sediments are accumulating near to their respective coasts except for a deposit along the southwestern coast of korea in which a considerable amount of sediment from chinese rivers has been accumulating c 2016 elsevier ltd all rights reserved

radiosity approach for the shortwave surface radiation balance in complex terrain the influence of topography on the radiation balance in complex terrain has so far been investigated either with very simple or very sophisticated approaches that are limited respectively by an uncontrolled spatial representation of radiative fluxes or heavy computational efforts to bridge this gap in complexity this paper proposes the radiosity approach well known in computer graphics to study anisotropic reflections of radiation in complex terrain to this end the radiosity equation is rederived in the context of three dimensional radiative transfer the discretized equation is solved by means of an adapted version of progressive refinement iteration to systematically study terrain effects the geometrical disorder provided by the topography is considered in its simplest approximation by gaussian random fields these model topographies capture the most important length scales of complex terrain namely a typical elevation and a typical valley width via the variance and the correlation length of the field respectively the mean reflected radiation is computed as a function of these length scales and sun elevation thereby explicitly addressing finite system sizes and grid resolutions a comparison with an isotropic parameterization of terrain reflections reveals that mean values are similar whereas spatial distributions vary remarkably it is also shown that the mean reflected radiation in real topography is reasonably well characterized by the gaussian approximation as a final application of the method the effective albedo of a topography is shown to vary with sun elevation and domain averaged albedo leading to albedo differences up to 0 025

multielement geochemistry of offshore sediments in the southeastern yellow sea and implications for sediment origin and dispersal abstract in total 116 surface sediments were collected from an offshore area of the southeastern yellow sea including a large mud belt southeastern yellow sea mud seysm and analyzed for grain size and geochemical composition organic carbon and 42 elements principal component analysis revealed that elemental compositions of the offshore sediments were mostly controlled by common aluminosilicate clay minerals and quartz most elements heavy minerals hf zr u th rare earth elements rees biogenic calcium carbonates ca sr feldspar and mica k ba pb and mn oxides mn oxide coatings on sand grains notably total ree concentrations may be associated with heavy minerals possibly zircon and monazite especially in silty grains even though heavy ree hrees concentrations are more strongly controlled by clay minerals in muddy sediments the diagnostic discrimination plots of geochemical compositions e g fe vs al mg vs al light ree vs hree and la lu ucc vs la y ucc suggested that the offshore sediments especially in seysm deposits were composed of a mixture of korean river derived silts and chinese river derived clays this demonstrated that chinese river sediments especially clay particles largely contributed to the formation of the giant mud belt in the korean coastal area furthermore the observed geochemical end members provide new markers of sediment provenance which can be used to track dispersal patterns and sediment limits from chinese and or korean rivers