basin development and syntectonic sedimentation associated with kinematically coupled strike slip and detachment faulting southern nevada a previously unrecognized 12 10 ma clastic sequence is distributed widely south of the las vegas valley shear zone and north of lake mead in southern nevada structural and stratigraphic evidence from these sedimentary and associated volcanic rocks suggests that basin development was kinematically related to movement along the las vegas valley shear zone major movement along the nearby saddle island detachment also occurred within this time interval we suggest that spatially and temporally related basin development sedimentation and stratal tilting reflect kinematically coupled movement along a combined las vegas valley shear zone saddle island detachment fault system

characterization and migration of atmospheric ree in soils and surface waters abstract rainwater and snow collected from three different sites in france vosges mountains french alps and strasbourg show more or less similar shapes of their ree distribution patterns rainwater from strasbourg is the most ree enriched sample whereas precipitations from the two mountainous less polluted catchments are less ree enriched and have concentrations close to seawater they are all strongly lree depleted different water samples from an alpine watershed comprising snow interstitial puddle and streamwater show similar ree distributions with lree enrichment rainwater normalized but mree and hree depletion in this environment where water transfer from the soil to the river is very quick due to the low thickness of the soils it appears that ree in streamwater mainly originate from atmospheric inputs different is the behaviour of the ree in the spring and streamwaters from the vosges mountains these waters of long residence time in the deep soil horizons react with soil and bedrock ree carrying minerals and show especially significant negative eu anomalies compared to atmospheric inputs their sr and nd isotopic data suggest that most of the sr and nd originate from apatite leaching or dissolution soil solutions and soil leachates from the upper soil horizons due to alteration processes strongly depleted in ree carrying minerals have ree distribution patterns close to those of lichens and throughfall throughfall is slightly more enriched especially in light ree than filtered rainwater probably due to leaching of atmospheric particles deposited on the foliage and also to leaf excretion data suggest that sr and nd isotopes of the soil solutions in the upper soil horizons originate from two different sources 1 an atmospheric source with fertilizer dust and seawater components and 2 a source mainly determined by mineral dissolution in the soil these two different sources are also recognizable in the sr and nd isotopic composition of the tree s throughfall solution the atmospheric contributions of sr and nd to throughfall and soil solution are of 20 to 70 and 20 respectively in springwater however the atmospheric sr and ree contribution is not detectable

environmental changes since 8 4 ka reflected in the lacustrine core sediments from nam co central tibetan plateau china the tibetan plateau induces and enhances the asian monsoon that influences the plateau itself east china and even the whole of asia pursuing the changing monsoon history and its impact in this environment sensitive area is a key for understanding the climatic changes here we present the initial results from core sed iments in nam co central tibet to elucidate the holocene environment changes in this area the studied lake nam co is the second largest lake with an elevation of 4718 m water area of 2015 km 2 and catchment area of 10 610 km 2 by using echo seismic profiling and hydro echosounding we investigated the bathymetric dis tribution of the whole lake one 332 cm long piston core was successfully taken in the east part of the lake at 60 m water depth twelve ams 14 c dates from top to bottom of this core established a good time sequence toc tn n alkanes grain size clay minerals fe mn sr ba and caco3 content were analysed with sampling intervals from 1 cm to 10 cm results showed that since 8400 yr bp the environment changes in this region indicate three stages the early stage 8400 6900 yr bp was characterized by slight shifting from warm to cold with a cold dry interval at 8100 7800 yr bp the middle stage was from 6900 to 2900 yr bp during which cli mate changed from warm humid to cold dry however around 2900 yr bp the climate once was slightly cold but strongly dry the late stage from 2900 yr bp to present was characterized by a general tendency toward cold dry the first temperature decline was around 1700 1500 yr bp following which temperature increased once before decreasing again around 600 300 yr bp which might be the result of the little ice age

controls on the geochemistry of rare earth elements along a groundwater flow path in the carrizo sand aquifer texas usa groundwater samples were collected along a groundwater flow path in the carrizo sand aquifer in south texas usa field measurements that included ph specific conductivity temperature dissolved oxygen do oxidation reduction potentials eh in mv alkalinity iron speciation and h2s concentrations were also conducted on site the geochemistry i e concentrations shale normalized patterns and speciation of dissolved rare element elements rees in the carrizo groundwaters are described as a function of distance along a flow path eh and other redox indicators i e do fe speciation h2s u and re indicate that redox conditions change along the flow path in the carrizo sand aquifer within the region of the aquifer proximal to the recharge zone groundwaters exhibit both highly oxidizing and localized mildly reducing conditions however from roughly 10 km to the discharge zone groundwaters are reducing and exhibit a progressive decrease in redox conditions dissolved ree geochemical behavior exhibits regular variations along the groundwater flow path in the carrizo sand aquifer the changes in ree concentrations shale normalized patterns and speciation indicate that rees are not conservative tracers with flow down gradient redox conditions ph and solution composite and adsorption modify groundwater ree concentrations fractionation patterns and speciation

rare earth elements and nd and pb isotopes as source indicators for labrador sea clay size sediments during heinrich event 2 elemental abundances and nd and pb isotope ratios were determined on samples from the carbonate free clay size fractions of sediments from intervals above within and below heinrich event 2 h 2 in core hu87 9 from the northwest labrador sea slope in hu87 9 rare earth element ree distributions and elemental concentrations within the h 2 event are distinct from those outside this event end 0 and 206 pb 204 pbdata also indicate different values for sediments deposited within and outside the h 2 event comparisons of ree patterns from the h 2 interval with those from bedrock units in baffin island northern quebec and labrador indicate that the lake harbour group lhg which crops out on the north side of the hudson strait is the most probable bedrock source of the clay size fraction found within the h 2 interval in hu87 9 the tasiuyak gneiss tg and lac lomier complex llc have ree patterns including a negative eu anomaly similar to those found in h 2 sediments however the la ybratios of these units are smaller than those associated with h 2 sediments the nd and pbisotope data support and complement ree based interpretations of provenance i e the nd pb signatures of sediments deposited at the hu87 9 site during the h 2 event are similar to nd pbsignatures ob tained on diamicts from the western end of hudson strait published by elsevier science ltd

spatial variability and the controlling mechanisms of surface sediments from nam co central tibetan plateau china abstract sixty six surface sediments were retrieved from nam co central tibetan plateau to evaluate the spatial variability of their distributions and controls across the entire lake grain size distribution total carbon total nitrogen total sulfur 210 pb and 137 cs activities and carbon and oxygen isotopes of carbonate of the bulk sediments were analyzed and the correlations among these variables as well as water depth were calculated the results showed distinct spatial variability for all variables the grain size distribution provides adequate information to reflect water energy levels within the lake based on these factors the accumulation zone of nam co was distinguished from the erosional and transportation zones the results indicate that the deep area 80 m of the central main basin and the centre of the eastern small basin serve as the accumulation zones in nam co water depth is the most important factor influencing the distribution of the surface sediments because all variables show different distribution patterns in shallow and deep areas additionally river input sediment focusing grain size effects and heterogeneous physicochemical features of the lake water as well as possible currents within the lake also play different roles that affect surface sediment characteristics water depth noticeably affects grain size and the 13 c and 18 o values of carbonate sediment implying that these proxies could be used as indicators of lake level change these findings are of significance for palaeoenvironmental interpretations when using these proxies

rock types and permeability prediction from dipmeter and image logs shuaiba reservoir aptian abu dhabi the shuaiba formation is a complex carbonate reservoir characterized by small scale geological heterogeneity primarily related to rudist macrofauna the textural heterogeneity corresponds to extreme permeability variation that is the controlling factor in reservoir production because of the large vertical resolution contrast between cores actual scale and conventional logs averaged responses over a few feet extrapolation of small scale heterogeneity into uncored wells using a traditional approach is unreliable high resolution log data like dipmeters and image logs are required to characterize small scale heterogeneity that is essential to a good three dimensional 3 d geological model that predicts true reservoir behavior our study illustrates an approach to improve the reservoir characterization of the shuaiba by quantifying small scale heterogeneity using dipmeter and image logs a methodology is proposed to use the existing high resolution high resolution dipmeter tool hdt stratigraphic high resolution dipmeter tool shdt and formation microscanner fms and conventional log data to characterize and extrapolate geological heterogeneity texture and neural network analyses derived from microresistivity variations and a multiregression approach have been used in two wells to demonstrate the methodology both rock types and permeability are estimated for extrapolation into uncored wells although differences between the conductivity of conductive and resistive areas when normalized for background conductivity are an indirect measure of permeability for hdt and shdt the connectivity coefficient of conductive anomalies derived from textural analysis is related to permeability in the case of fms reservoir rock types rrt obtained from the methodology correlate well with rrts derived from the integration of core special core analysis scal and conventional log data in two test wells permeability estimations including small scale extreme variations from less than 1 md in tight mudstones to greater than 1 d in caprinid rudstones are in good agreement with the core plug permeability measurements after a simple calibration in one example permeability trends in rudist rrts which are not discernible using core plugs and minipermeameter data are clearly resolved using shdt data the degree of correlation between estimated and core permeabilities is greater with increased vertical resolution of the tool hdt lowest fms highest distinct rrts resulting from small scale geological heterogeneity can be classified and permeability can be estimated with a high degree of confidence providing a better pathway of extrapolating from core data to conventional logs for 3 d modeling the methodology has potential application to other carbonate and siliciclastic reservoirs with appropriate calibration and scaling underused hdt shdt fms and fullbore formation microimager fmi databases are available in many other areas that could be analyzed an order of magnitude improvement in the ability to characterize small scale heterogeneity has significant implications for future coring logging programs and reservoir characterization efforts duffy russell is a senior carbonate geologist at saudi aramco in the reservoir characterization department southern fields characterization division he received b s and m s degrees in geology from north carolina state university in 1976 and duke university in 1979 and a ph d in geology from the university of aberdeen in 2001 he started his career as a geophysicist with amoco production company in 1979 and has worked nearly 21 years as a geologist for mobil oil corporation and exxonmobil specializing in carbonate reservoir characterization mahmoud akbar is a principal geologist for schlumberger working iran qatar the united arab emirates oman and yemen he started his professional career with schlumberger wireline and testing in 1985 in pakistan he received b sc 1983 and m sc 1985 degrees in applied geology from the university of punjab pakistan he has carried out research in the lower himalayas on factors controlling fractures and their effect on rock strength badarinadh vissapragada is a senior petrophysicist with schlumberger data and consulting services abu dhabi united arab emirates he did his postgraduate study in geophysics at andhra university waltair india he has more than 19 years of petrophysics experience in india and middle east reservoirs from fieldwide petrophysical studies and reservoir characterization his special interests are reservoir rock typing permeability and fracture detection gordon walkden is head of the department of geology and petroleum geology at the university of aberdeen scotland after receiving a degree from quintin school in london he obtained his ph d in carbonate sedimentology from manchester university united kingdom in 1970 gordon was appointed senior lecturer in 1988 and became department head in 1993 he has extensive field experience and supervision of research projects in britain europe north america and the middle east

geochemistry of daihai lake sediments inner mongolia north china implications for provenance sedimentary sorting and catchment weathering abstract to advance the understanding of sediment distribution catchment weathering hydraulic sorting and sediment provenance in a tectonically stable basin the geochemistry of surface sediment samples from daihai lake in north china is presented mud bulk sediments were analyzed for 10 major and 30 trace elements organic carbon and nitrogen and for 87sr 86sr ratios in silicate fraction acid insoluble ai and carbonates acid soluble as enrichment in fe2o3 cao mno mgo k2o and p2o5 and their positive correlation with al2o3 rb sr ratios and bivariate discrimination diagrams of k vs rb and th u vs th suggest low chemical weathering intensity under semiarid conditions in the daihai catchment accumulation of clays in deeper water sites by sedimentary sorting results in an evident distribution of sediment composition with the lake water depth although similar chondrite normalized ree rare earth element patterns of lake sediment samples with lree light rare earth element enrichment negative eu anomalies and an almost flat hree heavy rare earth element pattern may suggest similar sedimentary source rocks original sediment provenance can be recognized on the basis of their distinctive 87sr 86sr ai ratios and immobile th zr ti and nb trace element signature separating from weathering and sedimentary processes as well as from grain size effect

rare earth elements ree and yttrium in stream waters stream sediments and fe mn oxyhydroxides fractionation speciation and controls over ree y patterns in the surface environment we have collected 500 stream waters and associated bed load sediments over an 400 km 2 region of eastern canada and analyzed these samples for fe mn and the rare earth elements ree y in addition to analyzing the stream sediments by total digestion multi acid dissolution with metaborate fusion we also leached the sediments with 0 25 m hydroxylamine hydrochloride in 0 05 m hcl to determine the ree y associated with amorphous fe and mn oxyhydroxide phases we are thus able to partition the ree into dissolved 0 45 lm labile hydroxylamine and detrital sediment fractions to investigate ree fractionation and in particular with respect to the development of ce and eu anomalies in oxygenated surface environments surface waters are typically lree depleted la sm nasc ranges from 0 16 to 5 84 average 0 604 n 410 where the ree are normalized to the north america shale composite have strongly negative ce anomalies ce ce nasc ranges from 0 02 to 1 25 average 0 277 n 354 and commonly have positive eu anomalies eu eu nasc ranges from 0 295 to 1 77 average 0 764 n 84 in contrast the total sediment have flatter ree y patterns relative to nasc la sm nasc ranges from 0 352 to 1 12 average 0 778 n 451 and are slightly middle ree enriched gd yb nasc ranges from 0 55 to 3 75 average 1 42 most total sediments have negative ce and eu anomalies ce ce nasc ranges from 0 097 to 2 12 average 0 799 and eu eu nasc ranges from 0 39 to 1 43 average 0 802 the partial extraction sediments are commonly less lree depleted than the total sediments la sm nasc ranges from 0 24 to 3 31 average 0 901 n 4537 more mree enriched gd yb nasc ranges from 0 765 to 6 28 average 1 97 and ce and eu anomalies negative and positive are more pronounced the partial extraction recovered on average 20 of the fe in the total sediment 80 of the mn and 21 29 of the rees ce 19 and y 32 comparison between rees in water partial extraction and total sediment analyses indicates that rees y in the stream sediments have two primary sources the host lithologies i e mechanical dispersion and hydromorphically transported the labile fraction furthermore eu appears to be more mobile than the other ree whereas ce is preferentially removed from solution and accumulates in the stream sediments in a less labile form than the other rees y despite poor statistical correlations between the rees y and mn in either the total sediment or partial extractions based on apparent distribution coefficients and the ph of the stream waters we suggest that either sediment organic matter and or possibly d mno2 feooh are likely the predominant sinks for ce and to a lesser extent the other ree in the stream sediments

rare earth element behavior in soils and salt pan sediments of a semi arid granitic terrain in the western cape south africa the rare earth element ree contents of soils and pan sediments of the darling hills granitic terrain of southwestern south africa were determined to study the behavior of ree during weathering in a semi arid mediterranean climate the p rich stype bedrock granite has a middle ree mree enrichment relative to post archean australian sedimentary rocks paas that primarily reflects the ree content of feldspar and accessory apatite initial chemical weathering of the granite results in the loss of ree particularly ce eu and the heavy ree hree the enrichment of ree in soils relative to bedrock granite corresponds to clay mineral and amorphous fe oxide content in the case of the light ree lree and precipitation of pedogenic calcite in the case of the hree quartz sand dilutes the ree content and concentration of k feldspar produces positive eu anomalies cerium is rapidly precipitated during weathering and retained in clayey upper soil horizons as insoluble ceo2 most pan sediments have a bowl shaped ree pattern that is derived from the accumulation of eroded catchment soils modified by precipitation of evaporative carbonates ree enrichment particularly lree and the large negative ce anomaly of oxidized basal pan sediment relative to the bedrock granite suggest that ree entering the pan by groundwater flow are sorbed onto amorphous fe oxides in contrast goethite rich nodules from the pan have a low ree content and show hree enrichment relative to the granite precipitation of pedogenic calcite and evaporative pan carbonates greatly increases the retention of the hree in these semi arid soils diagenetic pan dolomite has a ree pattern similar to pedogenic and evaporative calcite but with a significantly lower ree content the ree patterns indicate that although most abundant in the bedrock granite the mree are least retained by soils during weathering the lree are generally retained by clayey and amorphous fe oxide rich soils and sediments whereas hree are retained by precipitation of soil and pan carbonates d 2003 elsevier b v all rights reserved

geochemistry of the rare earth elements in hypersaline and dilute acidic natural terrestrial waters complexation behavior and middle rare earth element enrichments rare earth element ree speciation was modelled in acid 2 9 ph 3 5 hypersaline groundwaters from australia and from the palo duro basin in texas usa using a combined specific ion interaction pitzer model and ion pairing model the free metal ion species i e ln3 is the dominant form of dissolved rees in these systems accounting for 40 70 of the dissolved metal in groundwater from lake tyrrell victoria australia 50 90 of the rees in groundwater from lake gilmore western australia and always 90 of each ree in the texas groundwaters lakes tyrrell and gilmore are actually dry lakes that act as groundwater discharge zones the abundance of the free metal ion species increases in these waters with increasing ionic strength and with decreasing ph the free metal ion species is followed in abundance by ree sulfate and ree chloride complexes that account for 20 50 and 10 15 respectively of the dissolved rees in the groundwaters from lake tyrrell 15 30 and 5 20 respectively in the groundwaters from lake gilmore and 3 and 7 respectively in the palo duro basin groundwaters the groundwaters of the lake tyrrell system and the palo duro basin are enriched in the middle rees mrees compared to both the light rees lrees and the heavy rees hrees only nd sm and dy were determined in the lake gilmore groundwaters and consequently it is unclear whether these acid groundwaters are also enriched in the mrees previous investigators suggested that fe rich organic flocs ree phosphate complexation and solid liquid exchange reactions between terrestrial waters and mree enriched surface fe mn coatings suspended particulates or secondary mineral phases within aquifer materials may promote the development of mree enrichments in natural waters we propose that organic colloids and ree phosphate complexes are insignificant in acidic natural waters in regards to mree enrichments instead solid liquid exchange reactions or dissolution of surface coatings suspended particulates and or secondary phases as well as sulfate complexation more likely controls the development of mree enrichments in acidic natural terrestrial waters

holocene environmental changes in bangong co basin western tibet part 4 discussion and conclusions abstract a 12 4 m core taken in lake bangong provides a continuous holocene climatic record we summarize information on changes in stable isotope and radiocarbon balances in the lake hydrobiology and vegetal cover in the catchment deduced from detailed analytical results given in the three preceding papers the bangong record is then compared with the environmental history of the neighbouring lake sumxi also constructed from multidisciplinary analyses the two records show a major environmental change at 10 9 5 ka b p attributed to a rapid strengthening of the summer monsoonal circulation which led to wet warm conditions this event was followed by a long term trend toward aridity which culminated around 4 3 ka b p in western tibet maximum monsoon rainfall seems to have occurred from 9 5 to 8 7 ka b p and from 7 2 to 6 3 ka b p as two wet pulses separated by a reversal event centered on 8 0 7 7 ka b p our results broadly agree with the records from lake seling in central tibet and lake qinghai at the plateau s northeastern margin and with palaeoclimatic studies in western china which document conditions wetter and warmer than those of today during the early middle holocene the environmental fluctuations recorded in western tibet appear in phase with climatic changes recognized in tropical north africa suggesting that the 8 0 7 7 ka b p and the 4 0 3 0 ka b p dry events were caused by abrupt disequilibrium in the climatic system

nyainqentanglha shan a window into the tectonic thermal and geochemical evolution of the lhasa block southern tibet 1 in the nyainqentanglha nqtl massif southern tibet a late cenozoic se dipping normal fault exhumed an oblique section of crust in its footwall u th pb dating of zircon and monazite from footwall exposures reveals a collage of felsic intrusions including cretaceous early tertiary and miocene granitoids ages of the latter span 10 m y suggesting semicontinuous or episodic miocene magmatism geochemical and isotopic analyses show a gangdese arc affinity indicating significant mantle heat and mass transfer in their formation and semicontinuous calc alkaline magmatism throughout the cenozoic indo asian collision the undeformed nature of the footwall cretaceous and miocene granitoids suggests that mesozoic cenozoic lhasa block deformation was thin skinned being concentrated in supracrustal assemblages this coupled with the lack of migmatites exposed in the nqtl implies the exposed crust was not a partial melt zone nor involved in large scale channel flow some 40ar 39ar thermochronologic studies of footwall k feldspars reveal that samples collected within several kilometers below the normal fault cooled prior to emplacement of young leucogranites indicating little perturbation of the background thermal structure since 15 ma this plus high melting temperatures and the lack of penetrative granitoid deformation requires that the melts formed at lower crustal levels and were emplaced rapidly to the midcrust seismic reflection results showing high bright spot anomalies in the midcrust along the nqtl rift may have imaged the youngest magmatic episode or its associated hydrothermal system

trace element variability in single ostracod valves as a proxy for hydrochemical change in nam co central tibet during the holocene ostracod shells belonging to three taxa leucocytherella sinensis huang 1982 leucocythere dorsotuberosa huang 1982 and l dorsotuberosa f postilirata sensu pang 1985 were collected from two sediment cores from lake nam co on the central tibetan plateau two variants of la icp ms laser ablation inductively coupled plasma mass spectrometry spot and line scan analyses were used to investigate trace element concentrations mg sr ba u and rare earth elements rees in single ostracod shells the results suggest that the line scan method can provide better precision than the spot analysis and is therefore preferred no significant difference in trace element composition between taxa was detected in our study fluctuations of mg ca and sr ca in the shells show good agreement with the reported lake level changes during the holocene indicating that ostracod mg and sr can be related to palaeohydrochemical processes in this area a high correlation between ba ca and sr ca was detected in our study perhaps implying that both metals were controlled by the same mechanisms a possible relationship between ostracod u ca and the past redox conditions on the lake bottom is discussed relatively low and constant la ca was observed which could be due to the ree characteristics in the lake water or ostracod biological processes or even the associated fe mn and or organic contaminants future studies on more specimens from this area especially shells from living ostracods are essential to investigate the potential of ostracod ba u and rees for use as palaeoenvironmental indicators

mineralogical control of rare earth elements in acid sulfate soils abstract major trace and rare earth element concentrations were measured in porewater surface water and sediments at an acid sulfate soil site the concentrations of la and ce in porewater are up to 1 3 ppm there is a strong correlation between ree concentration and acidity except that the maximum concentrations were consistently found below the horizon of maximum acidity associated with an increase in ph to ca 4 and change in mineralogy from jarosite dominated to goethite dominated mottles jarosite replacement by goethite is as expected with the rise in ph which in turn is due to the occurrence of a fossil shell bed just below the rare earth element patterns in the porewaters are enriched in the mree with respect to post archaean australian shale paas measurements and calculations show that this is in accord with experiments on low degree partial dissolution of jarosite even when the jarosite itself is highly enriched in lree there is a clear fractionation in the patterns between the clay rich soil matrix which is slightly depleted in the lree when normalized to paas la ybpaas 0 5 and the secondary mineral phase jarosite which is enriched in the lree la ybpaas 15 50 the ree pattern in the porewater changes with the transition from jarosite to goethite rich mottles becoming relatively more enriched in the lree compared to the hree which is consistent with the incongruent dissolution of jarosite to form goethite and the release of greater amounts of jarosite ree to solution including proportionately more of the jarosite compatible lree maximum surface water ree concentrations in acidic water were 100 200 ppb la and ce ree patterns in surface water were very similar to the porewater transition zone enriched in the mree but asymmetric relatively enriched in the lree compared to the hree

multiple implications of rare earth elements for holocene environmental changes in nam co tibet abstract rare earth elements rees from a 332 cm long core surface sediments and soils of the lake shores were examined with the aim of evaluating their suitability as a paleo environmental proxy rees were transported into the nam co lake not only by runoff but also by wind concentrations of ree in the core range from 97 57 to 162 98 ppm with an average of 126 5 ppm from 171 3 to 475 7 ppm in the soils of shores and from 65 03 to 354 03 ppm in the surface sediments with an average of 130 64 ppm the ree average of soils is 158 9 ppm for the northern shore 214 72 ppm for the southern shore 244 ppm for the eastern shore and 289 69 ppm for the western shore the ree average of surface sediments is 114 45 ppm for the northern lake 115 73 ppm for the eastern lake 129 69 ppm for the western lake 144 38 ppm for the southern lake and 150 95 ppm in the center of the lake suggesting an accumulation of rees in the center of the lake the ratios of lree hree range from 8 to 11 85 for the core from 7 8 to 11 8 for the surface sediments and from 6 5 to 14 5 for the soils which suggesting that lree are richer than hree the ree distribution patterns of all samples are characterized by v shape curves with slightly negative ce anomalies from 0 83 to 0 99 and obviously negative eu anomalies from 0 28 to 0 72 mn played an active role on the ce anomaly the values of ce showed almost no variance suggesting a stable post depositional environment in the core the rees peaks of 140 ppm occurred at 6 9 ka 307 cm 5 9 5 5 ka 292 287 cm 2 2 2 0 ka 262 252 cm and 1 78 ka 212 cm corresponding to the beginning of environmental shifts and or events while the rees peak at 0 91 0 87 ka 107 102 cm and the rees valley of

a review on the applications of image logs in structural analysis and sedimentary characterization abstract image logs provide important information on lithology sedimentary textures paleoflow directions fractures and in situ stress analysis lacking of criteria used for establishing the image log facies limits the applications of image logs in sedimentary reservoir interpretation this paper provides a thoroughgoing review focusing on the recent applications of borehole image logs for sedimentological and structural description and interpretation and aims to establish image log facies which can provide guidelines in sedimentary reservoir interpretation this paper firstly summarizes the principles and basic characteristics of various imaging logging tools and then briefly introduces the pre processing workflow of the image log data then the generated images are used for depth and orientation shifts of cores by calibrating individual sedimentary and structural features descriptive and concise image log facies are established based on combinations of image textures including dip type dip pattern and color scheme and the characteristics as well as physical criteria for each individual image facies are summarized the established image log facies are then interpreted in terms of structural and sedimentological features such as lithology sedimentary structures vugs fractures and faults the image log facies and its stacking patterns are then used to interpret the lithofacies associations by calibrating with cores and conventional logs natural fractures and induced fractures are recognized by image logs and the principles of breakouts and drilling induced fractures for in situ stress analysis are reviewed then the applications of image logs in investigation of fracture attitudes and states as well as in computation of fracture parameters are summarized the procedures to evaluate fracture effectiveness through image logs are discussed at last the application of image logs for structural dip analysis is reviewed and image logs are used for recognizing faults fracture sets and attitudes of stratum through the dip patterns the basic procedures for paleocurrent reconstruction which includes dip picking of cross beddings structural dip determination and structural dip removal are reviewed then the paleocurrent directions of the lower cretaceous bashijiqike formation in the kuqa depression were reconstructed which could help further understanding of the depositional systems this review will help extend the utility of image logs in interpreting small to large scale sedimentary and structural features and bridges the gaps between well log analysis and sedimentary and structural interpretation

characterization of braided river delta facies in the tarim basin lower cretaceous application of borehole image logs with comparative outcrops and cores abstract borehole electrical image log with core like presentation is an efficient way to conduct sedimentary description in the subsurface the key is to set up a series of geological diagnostic criteria the subsurface lower cretaceous bashijiqike formation in the kelasu belt kuqa depression described as a sedimentary facies of braided river delta front has measured a mass of borehole image logs and open hole logs at depths more than 6000 m combined with comparative outcrops limited cores and thin sections high quality borehole images were fine calibrated to reveal their sedimentary details with the aim of subtle sedimentary interpretation in the uncored intervals the image elements all have corresponding geological indications the lithologies are interpreted including mudstones siltstones fine and medium sandstones and conglomerates and the sedimentary structures are interpreted in terms of various bedding types scoured surface and stacking modes thus interdistributary bay sandy or conglomerate subaqueous distributary channel and channel mouth bar are interpreted based on the lithologies sedimentary structures and textures basal and top contacts and succession variations furthermore determination of paleo current direction using borehole image logs is proposed for some time but is far from mature and need to consider tectonic deformation settings of studied stratigraphy based on this the paleo current in the kelasu belt is interpreted to flow southward from the southern tianshan to the depression during the early cretaceous which is consistent with the results derived from the heavy mineral analysis however the subaqueous distributary channels could frequently migrate locally and the paleo current direction changed at localities with an offset angle varied between 30 and 150 regionally the scale of single sand body decreases lakeward and the sand body may stretch at a maximum distance of 685 1 m along the flow direction the diagnostic criteria and the workflow for borehole image interpretation in this study will have potential application to subsurface sedimentary description and guide sedimentary architecture where cores are not available

the signature of river and wind borne materials exported from patagonia to the southern latitudes a view from rees and implications for paleoclimatic interpretations abstract riverine and wind borne materials transferred from patagonia to the sw atlantic exhibit a homogeneous rare earth element ree signature they match well with the ree composition of recent tephra from the hudson volcano and hence this implies a dominance of material supplied by this source and other similar andean volcanoes due to the trapping effect of proglacial and reservoir lakes the larger patagonian rivers deliver to the ocean a suspended load with a slightly modified andean signature that shows a ree composition depleted in heavy rees in this paper we redefine patagonia as a source of sediments which is in contrast with other sources located in southern south america quaternary sediments deposited in the northern and to a lesser extent in the southern scotia sea and most of the dust in ice cores of east antarctica have ree compositions very similar to the loess from buenos aires province and to patagonian eolian dust however we rule out buenos aires province as a holocene major source of sediments similarly to buenos aires loess a proximal facies it is likely that the ree compositions of most sediment cores of the scotia sea and antarctica reflect a distal transport of dust with an admixed composition from two main sources a major contribution from patagonia and a minor proportion from source areas containing sediments with a clear upper crustal signature e g western argentina or from bolivia s altiplano evidence indicates that only during the last glacial maximum patagonian materials were the predominant sediment source to the southern latitudes

use of the geochemical and biological sedimentary record in establishing palaeo environments and climate change in the lake ngami basin nw botswana sediment samples from a continuous 4 6 m profile in the dry bed of lake ngami in nw botswana were analysed for geochemistry and dated using both 14c and tl methods certain units in the profile were found to be diatom rich and these with the geochemical results were used as indicators of high and low lake levels within the basin the lake ngami sediments contain a high proportion of sio2 51 92 5 wt avg 72 4 wt and variable levels of al2o3 2 04 17 2 wt avg 8 88 wt based on elevated al2o3 and organic matter loiorgc results lacustrine conditions occurred at ca 42 ka until 40 ka and diatom results suggest that relatively deep but brackish conditions prevailed at 40 ka the lacustrine sedimentary record was terminated abruptly possibly by tectonic activity at ca 19 ka shallow aerobic turbulent conditions were prevalent but lake levels were at this time increasing to deeper water conditions up until ca 17 ka this period coincides with the late glacial maximum a period of increased aridity in the central southern africa region generally increasing sr ca ratios and decreasing loiorgc and al2o3 from ca 16 to 5 ka suggest decreasing inflow into the basin and declining lake levels based on the enrichment of lree results slightly alkaline conditions prevailed at ca 12 ka diatom results also support shallow alkaline conditions around this time these lake conditions were maintained primarily by local rainfall input as the region experienced a warmer wetter phase between 16 and 11 ka lake levels rose rapidly by 4 ka probably in response to enhanced rainfall in the angolan catchment these results indicate that lake levels in the lake ngami basin are responding to rainfall changes in the angolan catchment area and local rainfall the results confirm that the present day anti phase rainfall relationship between southern africa and regions of equatorial africa was extant during the late quaternary over the angolan highlands and nw botswana

rare earth elements in pore waters of marine sediments abstract the rare earth elements rees were measured in pore waters of the upper 25 cm of sediment from one site off peru and three sites on the california margin the pore water ree concentrations are higher than sea water and show systematic down core variations in both concentration and normalized pattern from these analyses and from comparison to other chemical species measured dissolved fe mn ba oxygen nitrate phosphate it is suggested that pore water rees can be grouped into three categories those that are from an fe source those that are from a poc source and cerium oxide rees from the fe source appear where anoxia is reached they have a distinctive middle ree mree enriched pattern the concentrations in this source are so elevated that they dominate ree trends in the fe oxide reduction zone the net result of flux from the poc source is relative enrichment of heavy rees hrees over light rees lrees reflecting remineralizing poc and complexation with doc a common linear ree pattern seen in both oxic and anoxic sediments is associated with this poc source as well as a hree enriched pattern that is seen in surficial sediments at the peru site overall the pore water results indicate that mn oxides are not an important carrier of rees in the oceans a ree biogeochemical model is presented which attempts to reconcile ree behavior in the water and sediment columns of the oceans the model proposes that poc fe oxide and ce oxide sources can explain the ree concentration profiles and relative abundance patterns in environments ranging from oxic sea water to anoxic pore water the model is also consistent with our observation that the ce anomaly of pore water does not exceed unity under any redox condition

the effect of magmatic intrusions on coalbed methane reservoir characteristics a case study from the hoskissons coalbed gunnedah basin australia magmatic intrusions can deteriorate coalbed methane reservoir quality by precipitating minerals in natural fracture and cleat system to date the effect of magmatic intrusions on coal rank and maturity has been studied extensively however their impact on fluid flow capacity and gas content is poorly investigated this study evaluates the impact of magmatic intrusions on reservoir characteristics of the hoskissons coal interval in the gunnedah basin eastern australia where numerous coal intrusion associations exist drill stem test dst borehole image logs and core data are used to determine fluid flow characteristics gas content and quality in 14 wells across the gunnedah basin the integration of borehole image logs and dst data analysis enables us to determine the existence openness and hydraulic conductivity of natural fracture and cleat systems in the hoskissons coal interval in addition available desorption canister data gas composition data and conventional well logs are interpreted to investigate probable thermal effect on gas content our analyses of different datasets reveal that the thickness of intrusions and their positions with respect to the hoskissons coal interval are variable in the studied wells permeability varies from 1091 md down to zero owing to heterogeneous fracture and cleat systems interpreted natural fracture cleat systems are well correlated with measured permeability from dst data analysis this highlights the role of open natural fractures cleats in fluid flow characteristics of the hoskissons coal interval results indicate that the mineralizing effect of hydro thermal fluids derived either from magmatic intrusions or coal itself is not a controlling factor in fluid flow capacity of the hoskissons coal interval in the studied wells this is described by either the distance between coal section and major intrusions in some wells or perhaps emplacement of intrusive bodies prior to development of cleat and natural fracture networks the destructive impact of intrusions on permeability is observed in one of the studied wells in which in situ stress perturbation is large due to presence of magmatic intrusions in sedimentary rocks variable in situ stress orientation can decrease fracture connectivity and consequently fluid flow properties are affected gas content largely varies in heat affected coal intervals this signature is the result of thermal effect fading with distance and is more pronounced when intrusions are in close proximity to coal intervals gas composition is variable in the studied wells gas composition data indicate that high quality desorbed gas with methane concentration higher than 90 could be found even in coal intervals which are heavily intruded c 2016 elsevier b v all rights reserved

rare earth element geochemistry of lake baikal sediment its implication for geochemical response to climate change during the last glacial interglacial transition sediments deposited on the bottom of lake baikal have contributed to the understanding of a long term environmental history of continents rare earth elements rees along with major elements and loss on ignition loi of baikal sediments were determined with the aim of evaluating their suitability for a new paleoenvironmental proxy our interest is concentrated on paleoenvironmental change during the last glacial interglacial transition lgit chondrite normalized ree patterns for baikal sediments show a similar variation to those for typical upper continental crustal materials three parameters of la yb n n chondrite normalized value ratio sree tio2 and eu anomaly were used to express detailed characteristics of baikal sediments depth profile of la yb n ratio shows abrupt change whose timing corresponds to the beginning of climatic warming inferred from the profiles of sio2 tio2 and loi in addition la yb n ratio sree tio2 and the degree of eu anomaly correlate with each other this suggests that inflow process of particulate materials into the lake may have changed during the lgit the analytical results of this study lead to the conclusion that ree is a useful paleoenvironmental proxy in the baikal region r 2007 elsevier ltd all rights reserved

mineralogy and geochemistry of the holocene lacustrine sediments in nam co tibet abstract the carbonates clays and major chemical compositions of lacustrine sediments in nam co lake were examined by x ray diffraction scanning electron microscopy and chemical analysis carbonates include monohydrocalcite mhc first report from china and in a high altitude lake low mg calcite and traces of dolomite mhc in nam co is developed in water 1 8 g l with high mg ca molar ratios 10 03 15 03 high ph 8 04 9 72 and the presence of bacteria algae diatom and ostracoda illite and mg chlorite provide a strong evidence for physical weathering in the holocene most ca and sr in sediments originate from carbonates as the molar ratios of ca and co32 are all less than 1 and the curve of sr is very similar to that of ca however most of the mg fe and rb are from clays the lake water shifted from a fresh water environment to an evaporative alkaline environment by 2 06 cal ka bp there was a depositional event that the depositional rate changed from 0 134 to 1 639 mm a at about 2 cal ka bp

paleoenvironmental interpretations of rare earth element signatures in mosasaurs reptilia from the upper cretaceous pierre shale central south dakota usa abstract rare earth elements were analyzed from fossil marine reptile mosasauridae bones collected from five superposed members sharon springs gregory crow creek degrey and verendrye of the upper cretaceous pierre shale at localities along the missouri river in brule buffalo hughes and hyde counties in central south dakota fossil bones from each member of the pierre shale have different rare earth element ree signatures that may be distinctive over wide geographic areas fossils from the sharon springs member have distinctive ree signatures that may be further subdivided into three superposed groups that correspond with the upper middle and lower sharon springs member ree signatures are distinctive from each stratigraphic unit therefore fossils eroded from their stratigraphic context may be assigned to their proper depositional unit based on ree signature comparisons differences in ree compositions of bones among members appear to result from differential mixing of oxygenated and anoxic seawaters if differences in mixing are interpreted as depth differences the lower sharon springs member was deposited in deep anoxic water water depths decrease in the middle and upper sharon springs and the overlying gregory and crow creek members were deposited in even more shallow water finally according to this interpretation the overlying degrey and verendrye members were deposited in progressively deeper marine waters but not as deep as the lower sharon springs these interpretations are generally consistent with those based on faunal diversity and eustatic sea level curves

development of a papua new guinean onshore carbonate reservoir a comparative borehole image fmi and petrographic evaluation abstract the depositional and diagenetic controls on carbonate platform evolution are notoriously heterogeneous and difficult to determine from standard subsurface wireline logging techniques here a combined borehole image fmi fullbore formation microimager and petrographic study allowed evaluation of depositional and diagenetic trends across an australasian subsurface buildup that is a major recent gas discovery the elk and antelope gas fields are hosted in tertiary reefal platformal and associated deep water carbonates in the present day foothills region of the fold and thrust belt in the gulf province of papua new guinea a full suite of fmi logs 2800 m and 292 thin sections mainly from sidewall cores and cuttings from both platform flank and shallow water deposits were evaluated during this study despite the obvious scale differences between the datasets there was some correlation between the independent petrography and fmi studies for a picking major facies boundaries and b interpretation of depositional environments the latter particularly for slope and deep water deposits however thin section petrography proved critical in understanding primary depositional textures and secondary alteration features through the shallow water carbonates where complex diagenetic overprinting had strongly impacted original fabric and or in regions affected by gas smearing the petrographic study allowed more detailed examination of diagenesis and its impact on rock fabric which links to the fmi textures component analysis and depositional textures identified in thin section are good indicators of original depositional environment full fmi coverage allowed textural definition on a dm m scale identification and characterisation of vertical changes and likely large scale variations in depositional environments and sequences it was clear from combining the results of the two studies that diagenesis as well as depositional fabric had a strong impact on resultant fmi facies the diagenetic overprinting would have been difficult to extract from the fmi data without the benefit of the petrographic work this study shows the merits of selective petrographic analysis to calibrate the quality of facies interpretation from fmi images and proved critical for enhancing and in places revising initial fmi interpretations

ecology of extant nummulitids and other larger benthic foraminifera applications in palaeoenvironmental analysis abstract larger benthic foraminifera lbf are important contributors to modern and ancient tropical shallow marine sediments over the past 30 years a substantial body of literature has built up on the ecology of modern lbf especially in terms of their environmentally sensitive depth distribution reproductive strategy and morphology and the symbiotic relationship between many larger foraminifera and photosynthetic algae over the same period the extinct genus nummulites which is abundant in eocene sediments of southern europe north africa and the arabian peninsula has increasingly been studied principally because significant volumes of hydrocarbons have been discovered reservoired within nummulitic limestones offshore tunisia and libya the modern ecological studies of lbf provide a powerful tool with which to develop palaeoecological models for fossil nummulites and other symbiont bearing larger foraminifera in the rock record

tectonic controls on carbonate platform evolution in southern papua new guinea passive margin to foreland basin the middle oligocene collision of the northern margin of the australian craton with a complex subduction system resulted in emplacement of a thrust mass and formation of a foreland basin that extended from the coral sea to the indian ocean the distribution of carbonate platform facies in southwestern papua new guinea reflects the transition from an eocene passive margin setting to the early stages of foreland basin evolution the initial basin configuration with terrigenous sedimentation confined to the proximal foredeep allowed carbonate deposition in the shallow environment adjacent to the peripheral forebulge subsequent southward migration of the basin resulted in a rapid increase in the area and thickness of carbonate platform deposition when the proximal foredeep became filled by detritus shed from the emerging orogen clastic sediments buried the platform and terminated carbonate deposition the history of the southern papua new guinea carbonate platform illustrates the paradox of carbonate deposition within the foreland basin whereby basin configuration initially encourages thick and extensive carbonate deposition but inevitably leads to terrigenous inundation and the demise of the carbonate platform

integrated 3 d reservoir modeling based on 3 d seismic the tertiary malampaya and camago buildups offshore palawan philippines three dimensional 3 d seismic interpretation and drilling results indicate complex sedimentary geometries of the malampaya and camago build ups offshore palawan philippines with localized progradation due to unidirectional offbank transport alternating with vertical aggradation successive reduction of size during buildup growth and backstepping of the protected landward margin in response to transgression ultimately appear to have triggered the demise of carbonate production and platform drowning the shallow water platform top sediments repeatedly show signs of subaerial exposure before reflooding a modeling functionality was developed to allow development of multiple scenario 3 d reservoir models in an exploration or appraisal stage the model enables merging of seismic scale observations based on 3 d volume and horizon analyses with subseismic scale information from well data however inherent noise within the seismic data introduced by the complex buildup morphology has resulted in inconsistent attribute distribution and fault dimming these difficulties are compounded by erratic velocity distribution within the limestone nonhyperbolic move out and a narrow relatively low frequency spectrum all of which prevent the use of the 3 d seismic volume as hard data but rather allow its use as a soft constraint for guiding the geological interpretation and ultimately the modeling process seismic data quality in such complex morphologic settings and scarcity of well data hamper greatly the use of geostatistically driven modeling approaches therefore a new functionality was developed within shell s proprietary integrated 3 d modeling suite geocap which allows deterministic model reservoirs using seismic horizon and volume interpretation sequence and cyclo stratigraphic architecture and the concept of reservoir rock type seismic velocity in clean carbonate formations is predominantly a function of porosity distribution to assess time to depth conversion uncertainty the reservoir rock type based models were first produced in the time domain only after differential 3 d depth conversion of these models could the scenarios be reconstructed in the depth domain the depth models subsequently were used to derive permeability and saturation 3 d distortions and thus hydrocarbon volumes for each deterministic scenario the models were then used for simulation purposes

geochemical characteristics of lake clay drilled in well qz 4 its implication for geochemical response to climate change in the central tibetan plateau in the middle late pleistocene a colour sequence which is composed of a yellow subsequence in the lower unit and a grey subsequence in the upper unit is an important climate archive for the central tibetan plateau in the middle late pleistocene however little study has been done on it in well qz 4 this colour sequence is thicker than 116 m which is an important climate archive for the central tibetan plateau in the middle late pleistocene in this work the esr dating and geochemistry analysis have been carried out to provide a preliminary insight into the paleo climate change in the central tibetan plateau it can be concluded that the 23 56 ka 125 96 149 52 ka bp time interval which is marked by the angular unconformity surface at 272 48 m in depth proves that the deposition of this colour sequence is dominated by gonghe movement after this movement chemical weathering is reduced however the sedimentation rate is increased from 0 18 to 3 5 m ka in the central tibetan plateau the climate became colder and drier in the middle late pleistocene which is roughly consistent with global paleo climate change at that time all these changes are correlated with the change of elevation and atmospheric circulation in the tibetan plateau and its surrounding area which are driven by the tectonic uplift of gonghe movement the gonghe movement is likely a driving force for the short lived spike at about 120 ka