experimental behaviour of compacted marls jurassic marls from abadia portugal were used in the construction of some motorway embankments large fragments of this evolving material remained after the construction process and their degradation was of concern because of the expected change of the engineering properties of the compacted material the material exhibits a very complex behaviour which is difficult to reproduce with existing constitutive models for unsaturated structured materials this paper focuses on understanding and providing data on the interaction between the pure marls rock and the aggregate behaviour it presents the main results of tests performed to characterise the hydro mechanical behaviour of compacted marls in specimens prepared with different grading size distributions and subjected to oedometer tests where both stress and suction changes were applied the experimental data obtained were analysed considering the presence of fragments and their degradation the marl matrix was characterised to complete the existing

hydromechanical behaviour of compacted granular expansive mixtures experimental and constitutive study compacted granular mixtures of high density bentonite pellets have been evaluated as an alternative buffer material to fill the empty space around nuclear waste disposal canisters in horizontal drifts despite the obvious benefits of these compacted mixtures the backfilling operation becomes easier and the gaps between the host rock and the buffer are minimised there are several aspects of concern such as the effective blockage of the large inter pellet pores due to granule swelling this blockage improves the water permeability properties and the tendency to develop initial collapses before reaching an adequate swelling pressure selected test results of a comprehensive laboratory experimental programme are presented to gain insight into the hydromechanical response of this multi porosity compacted material to improve the information on local transient behaviour simulation assisted techniques using a double structure constitutive model are used the paper presents a physically based one dimension

relation between flow through and volumetric changes in natural expansive soils abstract geology and climate govern the evolution and behavior of natural expansive soils in the semi arid canadian prairies the regina clay deposit has a flat topography a homogenous composition and contains hair line fissures this research focuses on understanding the relation between flow through and volumetric changes in the natural expansive soil based on analysis of test data it is concluded that flow occurs through macro pores or fissures 5 10 8 m s during structural volume change and through micro pores or matrix 10 9 m s during normal and residual volume changes the hydraulic conductivity decreases by several orders of magnitude and becomes asymptotic vapor flow 2 10 14 m s during residual volume change a complete assessment of soil behavior requires water retention swell shrink and hydraulic conductivity curves the proposed straight line representation of the functions components is useful for predicting field response of expansive soils

origin of minerals and elements in the late permian coals tonsteins and host rocks of the xinde mine xuanwei eastern yunnan china abstract this paper reports the mineralogical and geochemical compositions of the late permian c2 and c3 coals both medium volatile bituminous coal from the xinde mine near xuanwei in eastern yunnan which is located close to the area with the highest female lung cancer mortality in china the two coals are characterized by high ash yields and low sulfur contents three factors including sediment source region multi stage volcanic ash generation and multi stage hydrothermal fluid injections were responsible for variations in the geochemical and mineralogical compositions of the xinde coals trace elements including v sc co ni cu zn se zr nb hf and ta are enriched in the coals and were mainly derived from the sediment source kangdian upland region major minerals in the samples of coal roof floor and non coal sediment partings include quartz kaolinite and chamosite as well as interstratified illite smectite and anatase chamosite in the coal was derived from reactions between kaolinite and fe mg rich hydrothermal fluids however chamosite in the roof strata was directly precipitated from fe mg rich hydrothermal fluids or was derived from the alteration of precursor minerals e g biotite by hydrothermal fluids quartz in some samples is very high especially in the roof strata of the c2 and c3 coal such high quartz along with minor minerals including pyrite chalcopyrite sphalerite calcite celestite vanadinite barite clausthalite and silicorhabdophane were derived from multi stage hydrothermal fluids the floors of both the c2 and c3 coal seams are fully argillized fine grained tuffaceous claystone and the immediate roof of the c2 coal is argillized coarse grained tuff the original materials of the floors and roofs of these coal seams were high ti alkali basaltic volcanic ashes as indicated by high tio 2 nb and siderophile elements and the distribution patterns of rare earth elements two intra seam tonstein layers in the c3 coal were identified based on their lateral persistence mineralogical mode of occurrence and composition as well as their elemental composition the tonsteins are dominated by kaolinite with minor quartz and possibly mixed layer illite smectite both tonsteins were derived from dacitic magma the ratios of nb ta zr hf and u th are much lower in tonsteins than in the adjacent coal benches which is attributed to the hydrothermal leaching

mineral composition and geochemical characteristics of the li ga rich coals in the buertaohai tianjiashipan mining district jungar coalfield inner mongolia abstract the coals from the jungar coalfield inner mongolia china have been found to be enriched in ga and li these are valuable metals that are potentially recoverable from coals and or coal combustion residues based on fifteen roof floor parting samples collected from one borehole and one hundred and forty one bulk coal samples collected from three boreholes in the buertaohai tianjiashipan coal mining district jungar coalfield this paper reports new data on the mineral compositions and geochemical characteristics of the jungar li ga rich coals and provides new evidence for the origin and mode of occurrence of al ga and li in these coals the main mineral phases occurring in the coals are kaolinite boehmite calcite with small proportions of quartz pyrite ankerite siderite and trace amounts of microcline and rectorite an unusual mineral phase svanbergite sral 3 po 4 so 4 oh 6 also occurs as a main mineral constituent in the studied coals the mineral phases in the roof floor parting samples are dominantly kaolinite with a small proportion of quartz kaolinite is of both terrigenous and authigenic origin which were possibly derived from terrigenous yinshan oldland sediment source region and or from recrystallization during the coal formation process boehmite and svanbergite are primarily of authigenic origin and were dominantly derived from the weathered bauxite sediment source region calcite may have formed by dissolution of limestone layers close to the margin of coal basin and subsequent deposition of the ca or mg rich carbonates in the cells fractures of the coal seams sulfide minerals in fractures may have been precipitated from epithermal fluids rectorite was probably formed by the reaction of kaolinite with epigenetic low temperature hydrothermal fluids during diagenesis compared to common chinese and worldwide coals the studied jungar coals are much more enriched in al 4 4 6 1 li 70 79 mg kg and ga 14 19 mg kg titanium p sr zr nb th ta hf and rare earth elements rees are also enriched in the studied coals to some extent aluminum in the coals mainly occurs in the form of kaolinite and boehmite whereas lithium may be associated with aluminosilicate minerals kaolinite and illite if present as well as svanbergite gallium principally occurs in kaolinite and to a lesser extent svanbergite strontium p and lrees la ce and rr nd and sm mainly present in svanbergite the source of li and ga in jungar coals is most likely from the yinshan oldland region but there is also a possibility of migration from bauxite of the benxi formation

a constitutive model for soft clayey rocks that includes weathering effects microstructural and mineralogical observations of clay stones reveal the presence of clay aggregates bonded by a skeleton of inert minerals such as calcium carbonate the behaviour of these natural materials evolves from a rock like behaviour when undisturbed to clay like soil when weathered or when subjected to straining a model has been developed to simulate the constitutive behaviour of these transitional materials following the proposal made by vaunat gens the material is conceived as a composite medium made of a clay matrix and a quasi brittle bonding microstructure the basic model has been modified and extended to reproduce the expansive behaviour of the clay matrix a fundamental aspect to simulate weathering effects induced largely by drying wetting cycles the clay matrix reacts to stress and suction changes whereas the bond component is not affected by suction changes an elasto plastic double structure model for expansive clay soils describes the clay matrix the bonding structure fol

compaction behaviour of clay this paper presents an experimental study of the compaction behaviour of non active clay one dimensional static compaction tests were carried out at high and medium water content with matric suction monitoring using trento high capacity tensiometers at lower water contents a transistor psychrometer was used to measure post compaction suction samples were compacted on the dry side of optimum to cover a wide range of compaction water contents and vertical stresses three water content regions were identified in the compaction plane depending on whether post compaction suction increased decreased or remained constant as the degree of saturation was increased at constant water content hydraulic paths of specimens subjected to loading unloading cycles at constant water content have clearly shown that post compaction suction may increase as the degree of saturation increases this non intuitive behaviour was demonstrated to be associated with the coupling between mechanical and water retention behaviour to this end a coupled mechanical water retention model was formulated irreversible one dimensional mechanical paths were modelled by a boundary surface in the space average skeleton vertical stress modified suction and void ratio irreversible hydraulic wetting paths were modelled by a boundary surface in the space suction degree of saturation and void ratio this study was completed by investigating the pore size distribution of compacted samples through mip tests

oxygen isotope analyses of fine silica grains using laser extraction technique comparison with oxygen isotope data obtained from ion microprobe analyses and application to quartzite and silcrete cement investigation the laser fluorination technique reported here for analyzing the oxygen isotope composition d 18 o of fine quartz size fractions 50 20 20 10 10 5 5 2 2 1 and 1 lm has been validated by comparison with the ion microprobe technique it yields accurate d 18 o data with an external precision better than 0 15 this is a significant methodological improvement for isotopic studies dealing with materials such as soil or biogenic oxides and silicates particles are often too small and recovered in insufficient amount to be easily handled for ion microprobe analysis both techniques were used to investigate d 18 o composition of a cretaceous quartzite and silcrete sequence from the southeast of france quartzite cements average 31 04 1 93 they formed from mid cretaceous seawater higher in the series silcretes cements average 26 66 1 36 they formed from upper or post upper cretaceous soil water and groundwater oxygen isotope data show that the silicification steps from one mineralogical phase to another and from one layer to another including from an upper pedogenic silcrete to a lower groundwater silcrete occurred in a closed or weakly evaporating hydrological system

stable isotope composition of bentonites from the swiss and bavarian freshwater molasse as a proxy for paleoprecipitation abstract the hydrogen and oxygen isotope compositions of bentonites and smectite rich tuffs from the north alpine foreland basin were measured for samples dated between 9 and 21 ma assuming clay mineral formation shortly after the deposition of the volcanic ash layers and at surface temperatures estimated from paleoclimatic studies the h and o isotope composition of water in equilibrium with the clay minerals can be calculated a comparison with values derived from other proxies of paleoprecipitation in the molasse basin such as pedogenic carbonates and mammal remains and 18 o values of carbonate in the bentonite beds suggests that the 18 o values of water estimated by this method are typical for foreland precipitation at this time and for this region therefore the 18 o value of smectite in bentonites and altered tuff layers can be a useful tool for studies of paleoclimate and topography there are however indications that the clay minerals did not retain their initial hydrogen isotopic composition but that a postformational exchange of h isotopes has occurred

soil water characteristic curve and consolidation behavior for a compacted silt measurement of the soil water characteristic curve swcc in the laboratory is commonly conducted under zero confining pressure however in the field the soil is under a confining stress therefore it is important to study the effects of the confining stress on swcc in addition the consolidation curve is normally generated under saturated conditions however the soil above the water table is usually unsaturated hence it is also necessary to investigate the effects of matric suction on the characteristics of the consolidation curves this paper presents the swccs under different net confining stresses and the isotropic consolidation curves under different matric suctions that describe the volume change characteristics of unsaturated soils with respect to stress state variables net normal stress and matric suction a series of swccs was determined for statically compacted silt specimens in a triaxial cell apparatus under different net confining stresses isotropic consolidation tests under differe

tonsteins of hat creek british columbia a preliminary study abstract the four superimposed coal zones a b c d lie in the hat creek graben in folded and faulted eocene strata the tonsteins of hat creek although numerous distinctive and matchable have yet to be studied in detail a composite log of ddh 106 606 m long was therefore constructed using 76 consecutive samples and earlier drill records to show coal zones a b c d seam and interseam material up to 72 tonsteins each 0 5 to 18 cm thick and layers of petrified wood and siderite zone a contains 28 tonsteins one every 6 4 m zone b 5 one every 16 4 m zone c 9 one every 8 2 m zone d 17 one every 6 4 m local overturning is indicated sedimentologically and possibly by the order petrified wood tonstein siderite and the similar tonstein density of zones a and d tonsteins from 329 m 247 m 229 m 212 m numbered 1 2 3 4 examined microscopically and by xrd xrf aa and infra red spectrophotometry consist of crandallite caa1 phosphate phytoclasts kaolinite ankerite calcite quartz anatase apatite and siderite allophane elemental values are variable tio 2 for nos 1 and 4 indicate a silicic magma for no 2 a mafic magma while no 3 is neither tio 2 al 2 o 3 ratios show no 1 to be silicic whereas nos 2 3 4 are neither sio 2 al 2 o 3 ratios are inconclusive an upward increase in k rb from 1 to 3 indicates either incrasing mafic ness or an increase in contaminant k rb sr values are low while ba sr have more in common with mafic than silicic rock future work on the tonsteins should include optical and sem analysis of the shards quantitative trace element modelling to determine magma sources and elemental analysis of the associated coal to determine whether in addition to the volcanic explosions represented by the tonsteins the original coal swamps were subjected to a continuous drizzle of volcanc dust as it is the tio 2 and tio 2 al 2 o for 64 samples of coal would if these elements were of magmatic and not detrital origin indicate silicic dust

hydro mechanical analysis of volcanic ash slopes during rainfall rainfall induced landslides in volcanic ashes represent a major natural hazard in many regions around the world due to their loose structure volcanic ash slopes are prone to rainfall induced landslides the paper presents a continuum modelling approach for the analysis of wetting induced instability phenomena at the onset of failure in loose volcanic ash slopes a numerical simulation of a landslide prone volcanic slope in costa rica is carried out with a 2d hydro mechanical finite element slope model a constitutive model based on the effective stress concept extended to partially saturated conditions is used to reproduce the volcanic ash hydro mechanical behaviour the model parameters were calibrated through a previous extensive laboratory testing campaign simulation results allow to anticipate the behaviour of the slope during rainfall infiltration and to analyze the development of the failure mechanism results of the coupled numerical model demonstrate the important role of wetting and drying cycles slope geometry and bedrock on the timely evolution of matric suctions and wetting induced deformations moreover it is observed that the pore collapse upon wetting enhances the development of a localised shear failure mechanism in unsaturated conditions

analysis origin and significance of mineral matter in coal an updated review abstract the material classed as mineral matter in coal embraces crystalline mineral materials as well as a range of inorganic elements that occur in non crystalline form this review outlines the methods that may be used to evaluate the percentage of mineral matter for a coal sample as opposed to the ash yield and to identify the minerals their individual percentages and their modes of occurrence within the coal the principal techniques include low temperature oxygen plasma ashing quantitative evaluation of x ray diffraction data observation using optical microscopy and a combination of observation chemical analysis and in some cases mapping based on scanning electron microscopy and related methods a range of other techniques may also be used to provide additional information on particular mineral matter components processes responsible for mineral matter formation include detrital input biogenic activity and authigenic precipitation at different stages of the coal s depositional and post depositional history differential migration of non mineral inorganic elements may also occur in lower rank coals and expulsion of non mineral inorganics may take place with rank advance knowledge of the mineral matter may be of assistance in understanding the modes of trace element occurrence with implications for assessing possible environmental impacts and also the potential for recovery of economic products from coal the behaviour of different mineral matter components at high temperatures is also discussed as well as methods for mineralogical analysis of ashes and other coal utilization products information from mineral matter studies may provide an improved basis for understanding coal formation and for evaluating the response of particular coals to different combustion gasification and coking processes

a laser fluorination method for oxygen isotope analysis of biogenic silica and a new oxygen isotope calibration of modern diatoms in freshwater environments abstract an empirical calibration for the oxygen isotope fractionation between biogenic silica and water was determined for diatom frustules sampled from living diatom communities in the jemez mountains of northern new mexico usa over a temperature range from 5 1 to 37 8 c the silica water fractionation is defined by the equation 1000 ln silica water 2 39 0 13 106t 2 4 23 1 49 this relationship is in close agreement with other published silica water fractionation factors for laboratory cultured diatom samples however it is as much as 8 lower than equilibrium quartz water fractionations and 3 4 lower than observed silica water fractionations in diatomaceous silica collected from sediment traps and sediment cores there are three possible explanations for the disparate silica water fractionation factors observed in diatom silica 1 silica does not precipitate in equilibrium with ambient water 2 silica does precipitate in equilibrium with ambient water but the silica water fractionation factor for diatom silica is considerably less than the equilibrium fractionation factor for quartz water or 3 silica precipitation is influenced by a vital effect where the 18o value of the water inside the diatom cell walls is lower than the 18o values of ambient water post mortem loss of organic material results in an alteration or maturation of diatom silica in which silica reequilibrates with a silica water fractionation closer to the equilibrium quartz water fractionation alteration is likely to occur rapidly after the diatom frustule loses its organic coating either as it settles through the water column or at the sediment water interface 18o values recorded by paleo diatom silica therefore do not record growing conditions but more likely record conditions at the sediment water interface in the case of lacustrine environments where the bottom water remains at a nearly constant 4 c the reequilibration of diatom silica with bottom conditions could reduce or remove the conflating effects of temperature on 18o values recorded by paleo diatom silica and provide direct information on the 18o value of the lake water

the vertical distribution of minerals in coal zones a b c d hat creek british columbia abstract the four superimposed coal zones a b c d lie in the hat creek graben in folded and faulted eocene strata 76 consecutive samples from ddh 75 106 were analysed by xrd and examined in polished section kaolinite and quartz are the major minerals with kaolinite increasing with depth some upper samples grade into halloysite montmorillonite bentonite is virtually absent illite mostly in zone a varies irregularly with depth appears to be antipathetic to dolomite and between 160 and 306 m to be associated with tonstein pyrite occurs throughout the core only above 358 m is it detected by xrd pyrite and siderite occur in polished section but in xrd appear to be unrelated zone c shows a marked deficiency in mineral varieties cristobalite is found throughout zone a and in the lower half of d major gypsum in the upper part of a and in the lower part of d no correlation exists between minerals and palynomorphs

oxygen isotope analyses of fine grained minerals and rocks using the laser extraction technique abstract the 18o values of fine grained materials made with the laser extraction technique are often lower than those obtained conventionally we propose a simple method to overcome this problem that involves the mixing of samples with a lif binder and pressing the powder into pellets prior to evacuation and analysis the presence of the lif allows for rapid fluorination of all minerals or whole rock samples to be made thus eliminating potential problems related to loss of partially reacted ejecta slow laser heating and incidental fluorination accurate isotope determinations of fine grained materials can be made with this method

assessing internal stress evolution in unsaturated soils 1 internal stresses in soils evolve as a result of the various interactions among soil particles and the pore fluids in response to natural or human induced activities whether attributed to suction structure or the various physicochemical forces that may develop assessing the internal stresses in soils has been an active area of research in soil science and engineering this paper presents the restrained ring method as an experimental tool for measuring the stresses that develop in a drying soil when it is restrained from shrinking freely the internal stress that develops can be related to the water content of the soil this method is validated using results for both silty clay loam and clay loam soils tensile stress at failure estimated from the restrained ring method was compared to tensile strength ranges of similar soils and a good correlation was observed moreover internal stresses measured by the restrained ring method were compared with existing empirical relationships using suction and degree of saturation this comparison concluded that suction is not the sole contributor to the soil s internal stress

origin and distribution of tonsteins in late permian coal seams of southwestern china abstract we have surveyed the areal and stratigraphic distribution of tonsteins in late permian coalfields of southwestern china over an area of several hundred thousand square kilometers we studied the relationship between tonstein distribution and sedimentary environment based on mineralogical and petrographic data we have concluded that these tonsteins originated as air fall volcanic ashes following accumulation in the peat swamps in situ alteration of the vitric and lithic components took place under acidic conditions leading to the formation of kaolinite based on petrologic mineralogic and chemical analytical data we have determined that the application of mineralogic and geochemical criteria for tonsteins may be useful in correlating coal beds predicting coal qualities and reconstructing related sedimentary paleoenvironmental conditions

experimental observations of the stress regime in unsaturated compacted clay when laterally confined construction processes often involve reformation of the landscape which will inevitably encompass compaction of artificially placed soils a common application of fill materials is their use as backfill in many engineering applications for example behind a retaining wall the post construction behaviour of clay fills is complex with respect to stresses and deformation when the fills become saturated over time heavily compacted fills swells significantly more than the lightly compacted fills this will produce enhanced lateral stresses if the fill is laterally restrained the work presented in this paper examines how the stress regime in unsaturated clay fills changes with wetting under laterally restrained conditions specimens of compacted kaolin with different initial conditions were wetted to various values of suction under zero lateral strain at constant net overburden pressure which allowed the concept of k0 the ratio between the net horizontal stress and the net vertical stress to be examined

modified state surface approach to the study of unsaturated soil behavior part ii general formulation in the previous companion paper a modified state surface approach was proposed to algebraically represent unsaturated soil behavior under isotropic stress conditions the present paper proposes a

a provenance study of mineral matter in coal from appalachian basin coal mining regions and implications regarding the respirable health of underground coal workers a geochemical and nd isotope investigation abstract this study presents geochemical data produced from the analysis of coal and adjacent rock samples retrieved from coal mining regions in the u s to examine mineral matter provenance study sites included the northern appalachian basin where the units of interest were the lower kittanning coal bed the overlying columbiana shale and the underlying paleosol allegheny formation additional study sites were located in the central appalachian basin where sampling was conducted on strata associated with multiple coal beds of middle and lower pennsylvanian age the central appalachian basin rock and coal samples were much lower in overall mineral matter and contained very little carbonate calcite and siderite or pyrite mineralogy which was common at the northern appalachian basin sites elemental analysis of rock samples indicated a trend of enrichment in ca mg mn na and k cations in the immediate overburden compared to the underlying rock in the central appalachian basin a similar trend was observed in coal related strata from the northern appalachian basin which was attributed to epigenetic marine incursions rare earth element ree concentrations were determined in the samples and showed eu and ce anomalies when normalized by chondritic values the total ree content of the overburden is generally less than that of the underlying rock units neodymium isotopic analysis of the lower kittanning coal overburden and paleosol from the northern basin indicate partial resetting of the sm nd system close to the time of deposition the data indicate a common appalachian source for the clastic mineral matter in the overburden underclay and coal mineral matter the geochemical findings of this study may provide a viable method for distinguishing respirable dust sources in both appalachian basins there are potential applications for this research to aid in the respiratory health of underground coal miners

changes in tensile strength and microstructure of loess due to vibration abstract loess soils typically have an open and metastable structure humidification and vibration can modify their microstructure and thus influence their mechanical behavior in the present study to investigate the influence of train vibration on the tensile strength behavior of loess the tensile tests were performed on loess specimens that had been vibrated at a low amplitude for a long period using a modified horizontal extensograph in addition the microstructures of vibrated and non vibrated loess specimens before and after the tensile tests were characterized changes in the loess microstructure due to vibration and that in the tensile test were analyzed the results show that the relationship between uniaxial tensile strength and water content in soil specimen could be represented using a power function the axial displacement at failure varies at the same manner as tensile strength with respect to water content in comparison to intact loess occurrence of less clay bridges and clay buttresses between aggregates or coarse particles is identified in the disturbed specimens while aggregates are seen to be a very little more loose in vibrated specimens after the tensile tests than that before the tensile tests this indicates that vibration reduces the tension resistance and ductility of loess soil structure which could be attributed to loss of bonding strength as a result of breakage of clay cementations and disintegration of aggregates in the tensile test the soil structure goes through two distinct phases of change i e stretching phase and cracking phase in the stretching phase the tensile deformations take place throughout the specimen without altering the contacts between soil particles significantly in the cracking phase weak cementations fail to resist tensile deformation and suffer from breakage once a through crack is developed the specimen breaks in two leading to a catastrophic drop of tensile stress

organic petrology of hat creek coal deposit no 1 british columbia abstract the upper eocene hat creek coal deposits of british columbia canada are one of the thickest lignite to subbituminous coal deposits of the world and comprise 350 550 m of coal samples of sedimentary organic material were taken from a 560 m interval of interbedded shale siltstone and carbonate that was penetrated by corehole 75 106 in the centre of the coal basin and the reflectances of huminite eu ulminite from coal and kerogen from the organic material were determined and petrographical analyses were made the coal deposit contains many leaf and resinite rich horizons and the reflectance of huminite in these horizons in lower than in corresponding horizons containing less liptinite when compared with huminite in adjacent coal beds the reflectance of huminite in shale is lower that in siltstone is similar and huminite associated with carbonate rocks has slightly higher reflectance values the petrological variation in the coal is mainly within the huminite group of macerals the coal at the top of the deposits is lignite r o 0 38 and becomes subbituminous c r o 0 50 at the base the inertinite content is very low indicating a low level of peat fire or oxidation the early stages of transformation of gelinite to macrinite are described the paleoenvironment appeared to be lacustrine as determined by organic petrological analysis of coals and interbedded sediments four major zones each containing many subzones were found paleoenvironments were similar for the a and c zones and also for the b and d zones

volcanogenic tonsteins from tertiary coal measures east kalimantan indonesia abstract laterally persistent tonsteins up to 30 cm thick occur in coal seams and associated sediments in the tertiary kutei basin of east kalimantan indonesia where neogene strata which form a generally eastward prograding marginal marine to fluvio deltaic sequence are disposed in a north northeast to south southwest striking fold belt centred on samarinda eight tonsteins have so far been recorded in the middle to upper miocene of the badak syncline some 40 km south southwest of samarinda and range from tonsteins in the strict sense kaolinite mudstones of wide stratigraphical extent including graupen and kristall varieties to smectite mudstones they may pass laterally into each other most contain pyroclasts in varying stages of alteration and are regarded as volcanogenic primary textures include microscopic vitroclastic aggregates completely argillised to smectite graded crystal tuffs with abundant sanidine glass shards and secondary vermiform kaolinite crystals and argillised lithic tuffs texturally and compositionally these tertiary tonsteins are closely similar to european carboniferous tonsteins and this strengthens the conclusion of a volcanogenic origin even where pyroclastic textures have been removed through alteration the east kalimantan tonsteins are of economic and stratigraphic significance in providing distinctive horizons which have proved useful in aiding correlation of boreholes drilled in a coal resource project in this area

vertical distribution of elements in deposit no 1 hat creek british columbia a preliminary study abstract four superimposed coal zones a b c d lie in the hat creek graben in folded and faulted eocene strata 65 samples from one central and representative drillhole are examined aa analyses show cu and zn as having an inorganic affinity and increasing upward reflecting either a change in environment of deposition or a more selective sorption srf analyses show six elements increasing in abundance with depth most pronounced first na ba si sr y mn with 12 decreasing rb cr k ni mg s ti fe ca zn p zr al does not vary the pronounced upward increase in rb might indicate the incorporation of increasingly silicic volcanic dust or sediment k rb ratios however show an upward zig zag variation while ba shows negative correlation with k sr ba ratios for zones a b d are similar to those for granite ti al na k ba sr rb sr and even the k rb ratios show that zones a and d appear to be structurally distinct of the 15 20 major stratigraphic coinciding highs and lows revealed in the element depth variograms 12 14 are in clean coal 5 6 in carbominerite the peaks may represent a the incorporation of volcanic ash or detrital sediment from different geological sources or b the concentration or removal of elements by groundwater aided by previously high geothermal gradients missing core may represent the position of former watertables drowned by repeated downward shifting of the graben more detailed collecting should permit cycles of deposition to be distinguished the coal zones can elementally be distinguished one from another but individually could be difficult to identify

experimental behaviour and modelling of an unsaturated compacted soil this paper reports the experimental study and modelling of the mechanical response of a silty sand used in the core of the metramo dam italy specimens were prepared by compacting the soil at optimum water content conditions using the modified proctor technique tests were performed under suction controlled conditions by a stress path triaxial cell and an oedometer the experimental program consists of 23 tests carried out in the suction range of 0 400 kpa the findings indicate the strong influence of suction on compressibility stiffness and shear strength the mechanical properties of the soil improve with suction following an exponential law with decreasing gradient furthermore the soil exhibited collapsible behaviour upon wetting even at low stress levels interesting results were also achieved in elastoplastic modelling as well the results led to characterization of soil behaviour with reference to widely accepted modelling criteria for unsaturated soils providing noteworthy suggestions about

unified hardening uh model for overconsolidated unsaturated soils naturally deposited clays are often unsaturated and overconsolidated within the frameworks of the barcelona basic model bbm for normally consolidated unsaturated clays and the unified hardening

oxygen isotope composition of annually banded modern and mid holocene travertine and evidence of paleomonsoon floods grand canyon arizona usa abstract holocene and modern travertine formed in spring fed havasu creek of the grand canyon arizona was studied to determine the factors governing its oxygen isotope composition analysis of substrate grown travertine indicates that calculated calcite formation temperatures compare favorably with measured water temperatures and include silt rich laminae deposited by monsoon driven floods ancient spring pool travertine is dated by u series at 7380 110 yr and consists of 14 travertine silt couplets of probable annual deposition one hundred eighty high resolution 18o analyses of this mid holocene sample average 11 0 pdb the average value for modern travertine is 0 5 lower perhaps because mid holocene temperature was higher or there was proportionally greater summer recharge 18o cyclicity in the mid holocene travertine has average amplitude of 1 9 0 5 pdb slightly less than the inferred modern day annual temperature range of havasu creek the annual temperature range might have been reduced during the 14 yr interval compared to present although other non temperature factors could account for the muted annual variation silt rich laminae within isotopically lower calcite in the modern and mid holocene travertine verifies the seasonal resolution of both samples and suggests that similar temperature precipitation conditions as well as monsoon generated summer floods prevailed in the mid holocene as they do throughout the grand canyon region today

the rapid heating defocused beam technique a co2 laser based method for highly precise and accurate determination of δ18o values of quartz abstract we describe a laser fluorination technique specifically for quartz that allows both high accuracy and high precision determination of oxygen isotope ratios regardless of grain size the rapid heating defocused beam technique rhd utilizes a defocused 32 w co 2 laser at full power which delivers 17 w 20 w mm 2 to the sample to quickly react quartz in contrast other recent laser fluorination studies use a tightly focused laser beam and slow heating i e sharp and kirschner 1995 fouillac and girard 1996 kirschner and sharp 1997 and find laser analysis of fine grained quartz to be inaccurate three quartz standards nbs 28 qz bra and qz cwru were analyzed using the rhd technique at the university of wisconsin to test for grain size effects rhd analyses show no correlation between grain size and 18 o values and are in excellent agreement with 18 o values obtained using conventional fluorination techniques additional analyses of the same quartz standards performed at university of wisconsin using slow heating and a focused beam yield 18 o values that are both less precise and significantly up to 0 8 lower than the accepted values attempts to use the rhd technique with a 20 w co 2 laser which delivers 8 w 10 w mm 2 to the sample at brgm were unsuccessful probably due to insufficient power density of the defocused beam we conclude that the rhd technique yields excellent accuracy and precision but that power densities of 15 20 w mm 2 may be necessary across a large part of the sample surface we recommend the use of lasers with at least 30 w of power

coupling hydraulic with mechanical models for unsaturated soils this paper presents an alternative method to couple the hydraulic component with the mechanical component in a constitutive model for unsaturated soils some pioneering work on hydromechanical coup

yielding and plastic behaviour of boom clay an underground research laboratory url has been excavated in a deposit of boom clay at a depth of 223 m by the sck cen belgian organisation near the city of mol this url is devoted to research into nuclear waste disposal this paper presents the results of an investigation carried out in the triaxial apparatus on specimens that were trimmed from blocks extracted during excavation sequences in the url in order to characterise the mechanical behaviour of the natural boom clay and to examine the effect of initial and induced anisotropy on its constitutive behaviour two series of triaxial tests were carried out special attention was devoted to the yield behaviour and the effects of stress history experimental results showed a clear relation between the shape of yield curves and stress history the yield curve of the clay in its initial state was oriented along the k0 line illustrating the anisotropy of fabric that was generated during the soil deposition subsequent isotropic compression up to 9 mpa

swelling phenomena and effective stress in compacted expansive clays the central aim of this paper is to discuss the applicability of the effective stress principle as defined by terzaghi total stress minus pore water pressure to predict the behaviour of expansive

a framework for the behaviour of unsaturated expansive clays the paper presents a framework for describing the mechanical behaviour of unsaturated expansive clays it is an extension of an existing formulation developed for unsaturated soils of low activity the extended framework is based on the distinction within the material of a microstructural level where the basic swelling of the active minerals takes place and a macrostructural level responsible for major structural rearrangements by adopting simple assumptions concerning the coupling between the two levels it is possible to reproduce major features of the behaviour of unsaturated expansive clays some selected qualitative comparisons between model predictions and experimental results reported in the literature are presented despite the simplified hypotheses made a very encouraging agreement is obtained key words capillarity clay model unsaturation suction expansive soils

soil structure of a highly weathered old alluvium the old alluvium in san juan puerto rico is an early pleistocene deposit that has undergone substantial post depositional weathering in a tropical climate preliminary geotechnical laboratory testing found that the soil exhibits some unusual index and consolidation properties compared with stereotypical sedimentary soils for instance both the swelling index and the coefficient of consolidation are greatly affected by the maximum past stress applied to the soil in order to understand its unusual behaviour a variety of experiments were performed to characterise its composition and microstructure direct observations of the microstructure used environmental scanning electron microscopy and indirect examinations included slaking cation exchange capacity selective chemical dissolution particle size analyses and atterberg limits the results clearly indicate that the weathered deposit possesses a complex microstructure the intact material consists of a stiff network of aggregates interconnected by fe

mechanical behaviour of unsaturated marine sediments experimental and theoretical approaches abstract the costa target areas exhibit different slope failure events which reflect different triggering mechanisms including gas hydrates dissociation gas hydrates stability law depends on temperature pore pressure gas chemistry and pore water salinity any change in the equilibrium parameters may convert the hydrate to gas plus water causing significant weakening of the sediment and generating a rise of pore pressure a significant consequence of the hydrate melting is the gas production which alters significantly the behaviour and mechanical properties of the marine sediments and could be very hazardous when the sediment is unloaded in undrained conditions the behaviour of the unsaturated marine sediment has to be accurately identified in order to quantify the geological risks associated to the hydrate dissociation see for instance sultan n cochonat p foucher j p mienert j this volume effect of gas hydrates melting on seafloor slope instability thus in this work five tests were carried out on synthetic marine sediments in order to identify the gas effect on the hydro mechanical behaviour of unsaturated marine sediments based on the experimental results obtained from this study on previous constitutive models alonso e e gens a josa a 1990 a constitutive model for partially saturated soils geotechnique 40 3 405 430 gens a alonso e e 1992 a framework for the behaviour of unsaturated expansive clays can geotech j 29 1013 1032 and on the relationship of van genuchten van genuchten m th 1980 a closed form equation for predicting the hydraulic conductivity of unsaturated soils soil sci soc am j 44 892 898 a new mathematical formulation was proposed to simulate the behaviour of the unsaturated soil qualitative comparison between experimental results and model predictions shows the capacity of the proposed model to reasonably reproduce the essential features of the hydro mechanical behaviour of marine unsaturated sediment experimental and simulation results show that unloading tidal cycles erosion natural slope instabilities excavation a submarine unsaturated sediment slope in shallow water is much more hazardous than unloading the same submarine slope in deep water

elements and phosphorus minerals in the middle jurassic inertinite rich coals of the muli coalfield on the tibetan plateau abstract the content modes of occurrence and origin of elements and phosphorus minerals in the jurassic coals of the muli coalfield on the tibetan plateau were investigated using optical microscopy field emission scanning electron microscopy in conjunction with energy dispersive x ray spectrometry x ray powder diffraction x ray fluorescence spectrometry and inductively coupled plasma mass spectrometry the muli coals l1 and l2 coals are of high volatile a bituminous to medium volatile bituminous rank characterized by low sulfur contents and are generally dominated by the inertinite group macerals predominantly semifusinite and fusinite the l1 coal contains abundant apatite 7 9 on average on an organic matter free basis and alumino phosphate minerals of goyazite gorceixite crandallite group 4 9 on average and accordingly the concentrations of elements f 253 g g on average p 2349 g g sr 526 g g and ba 790 g g are elevated as compared with common world hard coals the deposition of phosphorous bearing minerals in the muli coals was not derived from volcanic input penetration of ca and al rich solutions release of phosphorus from organic matter during plant decay and an appropriate sedimentary environment such as low ph low water table for peat and oxidizing conditions were critical factors in deposition of the phosphorus minerals

a microstructure based elastoplastic model to describe the behaviour of a compacted clayey silt in isotropic and triaxial compression the paper focuses on the hydromechanical behaviour of an unsaturated compacted clayey silt accounting for fabric changes induced by drying wetting cycles occurring at low stress levels the respon

the grootegeluk formation in the waterberg coalfield south africa facies palaeoenvironment and thermal history evidence from organic and clastic matter the grootegeluk formation of the waterberg coalfield is about 70 m thick and consists of relatively thin coal beds interbedded with numerous mudstone and carbonaceous mudstone layers maceral analyses of the coal seams and the interbedded carbonaceous mudstones show that vitrinite is the dominant maceral up to 90 vol whereas inertinite liptinite and reactive semifusinite generally occur in minor proportions the vitrinite content increases upward in the formation with a concomitant decrease in inertinite including reactive semifusinite from around 60 inertinite at the base of the formation the upward increase in the vitrinite concentration is associated with an increase in the energy of the depositional environment which is also considered to have been instrumental in the enhanced preservation of the vitrinite the repetitive nature of the coal mudstone succession the lateral persistence of cycles and the maceral and ash proportions indicate that the formation may have resulted from a combination of allogenic controls tectonism and climate and authigenic controls environments of deposition the vitrinite reflectance rmax of the grootegeluk formation mean 0 72 and palynological evidence indicate that the grootegeluk formation was subjected to maximum post depositional temperatures of about 100 c the lower portion of the grootegeluk formation is dominated by kaolinite quartz and minor amounts of apatite and the upper parts by quartz kaolinite and minor amounts of montmorillonite illite and microcline the base of the grootegeluk formation is considered to have been relatively more distal and the upper portions more proximal to the source of the sediments at the base of the grootegeluk formation a 2 m thick tonstein zone occurs which is dominated by well crystallised kaolinite organic matter 40 wt siderite calcite and minor proportions of apatite the tonstein zone has mineralogical maceral and chemical characteristics distinctive from the other mudstones calcite lenses which occur predominantly in the upper half of the grootegeluk formation are interpreted as syndepositional early diagenetic globular pyrite and spherulitic siderite occur in the coals and organic rich mudstones of the grootegeluk formation fine grained granular siderite is present predominantly in the organic poor mudstones of the grootegeluk formation and the overlying beaufort group systematic changes in the mineralogy and major element chemistry make major element whole rock chemistry an ideal stratigraphic indicator tool for the grootegeluk formation the tonstein has anomalously high concentrations of the trace elements sc v cr mn ni cu ge se br rb sr y zr nb mo ba la ce nd pb th and u and low concentrations of s co as and zn which in addition to its mineralogical character and correlation throughout the basin make the tonstein an important chronostratigraphic marker for local and intrabasinal correlation the overlying beaufort group mudstones contain no organic matter however interpretation of the mineralogical and chemical data indicates that they were deposited with organic matter which was later degraded the mineralogy of the mudstones and the concentration of trace elements suggest that the sediments were deposited in fresh rather than in marine waters

an 40 ar 39 ar rb sr and stable isotope study of micas in low grade fold and thrust belt an example from the swiss helvetic alps white micas in carbonate rich tectonites and a few other rock types of large thrusts in the swiss helvetic fold and thrust belt have been analyzed by 40ar 39ar and rb sr techniques to better constrain the timing of alpine deformation for this region incremental 40ar 39ar heating experiments of 25 weakly metamorphosed anchizone to low greenschist samples yield plateau and staircase spectra we interpret most of the staircase release spectra result from variable mixtures of syntectonic neoformed and detrital micas the range in dates obtained within individual spectra depends primarily on the duration of mica nucleation and growth and relative proportions of neoformed and detrital mica rb sr analyses of 12 samples yield dates of ca 10 39 ma excluding one anomalously young sample these dates are slightly younger than the 40ar 39ar total gas dates obtained for the same samples the rb sr dates were calculated using initial 87sr 86sr ratios obtained from the carbonate dominated host rocks which are higher than normal mesozoic carbonate values due to exchange with fluids of higher 87sr 86sr ratios and lower 18o 16o ratios model dates calculated using 87sr 86sr values typical of mesozoic marine carbonates more closely approximate the 40ar 39ar total gas dates for most of the samples the similarities of rb sr and 40ar 39ar total gas dates are consistent with limited amounts of detrital mica in the samples the 18o values range from 24 15 vsmow for 2 6 m micas and 27 16 for the carbonate host rocks the carbonate values are significantly lower than their protolith values due to localized fluid rock interaction and fluid flow along most thrust surfaces although most calcite mica pairs are not in oxygen isotope equilibrium at temperatures of ca 200 400 c their isotopic fractionations are indicative of either 1 partial exchange between the minerals and a common external fluid or 2 growth or isotopic exchange of the mica with the carbonate after the carbonate had isotopically exchanged with an external fluid the geological significance of these results is not easily or uniquely determined and exemplifies the difficulties inherent in dating very fine grained micas of highly deformed tectonites in low grade metamorphic terranes two generalizations can be made regarding the dates obtained from the helvetic thrusts 1 samples from the two highest thrusts mt gond and sublage have all of their 40ar 39ar steps above 20 ma and 2 most samples from the deepest helvetic thrusts have steps often accounting for more than 80 of 39ar release between 15 and 25 ma these dates are consistent with the order of thrusting in the foreland imbricating system and increase proportions of neoformed to detrital mica in the more metamorphosed hinterland and deeply buried portions of the nappe pile individual thrusts accommodated the majority of their displacement during their initial incorporation into the foreland imbricating system and some thrusts remained active or were reactivated down to 15 ma

mineralogy of the volcanic influenced great northern coal seam in the sydney basin australia abstract the mineralogy of the individual coal plies and intra seam claystone bands in the great northern seam of the sydney basin has been evaluated using optical and scanning electron microscopy and quantitative x ray diffraction techniques the uppermost two claystone bands are tonsteins consisting mainly of well ordered kaolinite with graupen to vermicular textures idiomorphic crystals of k feldspar within these tonsteins may represent members of the anorthoclase sanidine series or a sodic sanidine and indicate an acid to intermediate volcanic ash input in contrast the lowermost parting was largely derived from epiclastic sediment admixed with minor volcanic material such as high temperature quartz and a different type of k feldspar component the mineral fraction of the coals especially in the middle and upper parts of the seam is dominated by authigenic kaolinite with a very low abundance of quartz apart from the tonsteins authigenic processes therefore appear to be the dominant mechanism of mineral matter formation authigenic k feldspar also occurs in the lower few metres of the seam with a variety of modes of occurrence including cell and cleat infillings cross cutting veins and thin laminae parallel to the organic matter and detrital clay bands a late syngenetic low temperature hydrothermal fluid injection process is suggested for formation of the feldspar veins the origin of the fluid is uncertain but is most likely associated with contemporaneous volcanic activity