investigation of the vertical uplift capacity of deep water mudmats in clay subsea mudmats are used in deep water oil and gas fields to support seabed structures such as pipelines manifolds and well heads on soft soil removing mudmats during maintenance or decommissio

an ion microprobe study on trace element composition of clinopyroxenes from blueschist and eclogitized feti gabbros ligurian alps northwestern italy some petrologic considerations abstract detailed microtextural investigations coupled with ion microprobe trace element determinations have been performed on clinopyroxenes from blueschist and eclogitized fe ti gabbros from ligurian alps northwestern italy ion microprobe analyses have also been carried out on garnets from eclogitized fe ti gabbros the aim is to understand the relations between metamorphic reactions and trace element compositions of clinopyroxenes in high pressure low temperature terranes trace and major element analyses on relicts of igneous diopsides indicate similar protoliths for both eclogites and blueschists metamorphic clinopyroxenes have variable trace element compositions which reflect the compositions of original mineral phases in particular the clinopyroxenes replacing the igneous diopside commonly retain geochemical signatures of the precursor mineral such as relatively high sc y and hree contents the trace element variations among high pressure clinopyroxenes in different textural domains are greater for blueschists than for eclogites this reflects the more limited major element equilibration of blueschists relative to eclogites in deformed eclogites the clinopyroxenes lack the geochemical signatures of the original igneous minerals most probably due to the enlargement of reaction domains caused by synmetamorphic deformation trace element partitioning between omphacite and garnet suggests that in both undeformed and deformed eclogites chemical equilibrium is locally approached and therefore the trace element composition of clinopyroxenes is controlled by the coexisting minerals for instance clinopyroxenes in eclogites are strongly hree and lree depleted i e with bell shaped pattern due to the equilibration with garnet and allanite respectively the partition coefficients for rees between omphacite and garnet are markedly lower than those reported in the literature on the basis of crystal chemical considerations we suggest that this is probably due to lower temperature conditions during formation

t bar to spudcan design approach in single layer clays and calcareous silts abstractdifficulties in obtaining high quality soil samples from offshore sites and heavy involvement of lab testing and engineering judgment have necessitated increasing reliance on in situ penetrometer tests giving continuous penetration resistance profiles this paper reports a framework for estimating spudcan penetration resistance directly from continuous resistance profile of a full flow penetrometer t bar test in single layer clays and calcareous silts the framework was validated chiefly against centrifuge test data supplemented by some reported field data

reaction enhanced ductility the role of solid solid univariant reactions in deformation of the crust and mantle abstract in collision belts and subduction zones penetrative deformation of thrust sheets may be catalyzed by metamorphic reactions if the reactions have a significant effect on the mechanical properties of rocks reaction enhanced ductility may result if a reaction produces a significant decrease in grain size thus allowing the rock to deform superplastically the product grain size of a reaction is a function of the ratio of nucleation and growth rates this ratio varies along any pressure temperature time ptt path and only attains a significant value at a certain distance from an equilibrium boundary a comparison of rates of change of p and t along typical segments of ptt paths for crustal rocks leads to the conclusion that a high nucleation rate a small grain size and resulting superplastic deformation are more likely to be achieved when reaction boundaries are crossed during underthrusting rather than during the thermal readjustments of a perturbed geotherm following crustal thickening or during uplift an example of reaction enhanced ductility occurs in eclogite facies metagranitoids in the sesia lanzo zone western alps where medium grained plagioclase reacted to fine grained jadeite quartz during early alpine underthrusting microstructural evidence from shear zones shows that the jadeite quartz aggregates were highly ductile and it is inferred that the small grain size allowed superplastic deformation further evidence suggests that this process operated during regional deformation of metagranitoids rubie 1982 the reaction of olivine to spinel or the beta phase by metastable overstepping of the two phase stability fields in a subducting plate ringwood 1975 may result in fine grained products and thus may be analogous to the albite jadeite quartz reaction the consequent decrease in effective viscosity is likely to have important consequences for plate dynamics at and below the depths of major phase transitions

in situ dynamic piezocone penetrometer tests in natural clayey soils a reappraisal of strain rate corrections cone penetration testing with pore pressure measurement cptu is a cost and time efficient way of collecting in situ geotechnical parameters of near surface marine soils for cable and pipeline tr

rate and mechanism in prograde metamorphism for a given rate of heat input into a prograde metamorphic sequence the extent of overstep of reaction temperature disequilibrium depends on the slowest of three sequential steps a surface detachment of reactant minerals b transport of material to the site of mineral growth and c nucleation and growth of the product mineral we have developed analytical expressions which enable determination of the rates of mineral dissolution and growth and of advective and diffusive mass transport during metamorphism the dissolution and growth steps are linear functions of the driving force g of the overall reaction while diffusion may take place either through a grain boundary fluid film or through the disorganized grain boundary itself

geochemical constraints of the eclogite and granulite facies metamorphism as recognized in the raobazhai complex from north dabie shan china a combined study of major and trace elements fluid inclusions and oxygen isotopes has been carried out on garnet pyroxenite from the raobazhai complex in the north dabie terrane ndt well preserved compositional zoning with na decreasing and ca and mg increasing from the core to rim of pyroxene in the garnet pyroxenite indicates eclogite facies metamorphism at the peak metamorphic stage and subsequent granulite facies metamorphism during uplift a p t path with substantial heating from c 750 to 900 c after the maximum pressure reveals a different uplift history compared with most other eclogites in the south dabie terrane sdt fluid inclusion data can be correlated with the metamorphic grade the fluid regime during the peak metamorphism eclogite facies was dominated by n2 bearing nacl rich solutions whereas it changed into co2 dominated fluids during the granulite facies retrograde metamorphism at a late retrograde metamorphic stage probably after amphibolite facies metamorphism some external low salinity fluids were involved in situ uv laser oxygen isotope analysis was undertaken on a 7 mm garnet and impure pyroxene amphibole and plagioclase the nearly homogeneous oxygen isotopic composition 18ovsmow c 6 7 in the garnet porphyroblast indicates closed fluid system conditions during garnet growth however isotopic fractionations between retrograde phases amphibole and plagioclase and garnet show an oxygen isotopic disequilibrium indicating retrograde fluid rock interactions unusual morb like rare earth element ree patterns for whole rock of the garnet pyroxenite contrast with most ultra high pressure uhp eclogites in the dabie sulu area however the age corrected initial end t is 2 9 which indicates that the protolith of the garnet pyroxenite was derived from an enriched mantle rather than from a morb source combined with the present data of oxygen isotopic compositions and the characteristic n2 content in the fluid inclusions we suggest that the protolith of the garnet pyroxenite from raobazhai formed in an enriched mantle fragment which has been exposed to the surface prior to the triassic metamorphism

displacement rate effects during t bar cycling in remoulded gulf of mexico clay the influence of the displacement rate of a t bar on the remoulded shear strength of a soft natural lightly overconsolidated marine clay is investigated a series of t bar cyclic tests was carried out in 12 box cores collected from the gulf of mexico one general equation relating the displacement rate to the remoulded strength is presented which provides insight on rate effects for remoulded clays and which can be used to correct for remoulded penetration resistance data for natural soft clays for a t bar recorded at displacement rates other than the commonly used displacement rate of 0 020 m s

structural development and petrofabrics of eclogite facies shear zones bergen arcs western norway implications for deep crustal deformational processes caledonian eclogite facies shear zones developed from grenvillian garnet granulite facies anorthosites and gabbros in the bergen arcs of western norway allow direct investigation of the relations between macroscopic structures and crystallographic preferred orientation cpo in lower continental crust field relations on the island of holsnoy show that the eclogites formed locally from granulite facies rocks by progressive development of 1 eclogite adjacent to fractures 2 eclogite in discrete shear zones 2 m thick 3 eclogite breccia consisting of 80 well foliated eclogite that wraps around rotated granulite blocks and 4 anastomosing subparallel eclogite facies shear zones 30 100 m thick continuous over distances 1 km within the granulite terrane these shear zones deformed under eclogite facies conditions at an estimated temperature of 670 50 c and a minimum pressure of 1460 mpa which corresponds to depths of 55 km in the continental crust detailed investigation of the major shear zones shows the development of a strong foliation defined by the shape preferred orientation of omphacite and by alternating segregations of omphacite garnet rich and kyanite zoisite rich layers a consistent lineation throughout the shear zones is defined by elongate aggregates of garnet and omphacite the cpo of omphacite determined from five axis universal stage measurements shows a strong b axis maximum normal to foliation and a c axis girdle within the foliation plane with weak maxima parallel to the lineation direction these patterns are consistent with deformation of omphacite by slip parallel to 001 and suggest glide along 010 the lineation and cpo data reveal a consistent sense of shear zone movement although the displacement was small localized faulting of high grade rocks accompanied by fluid infiltration can be an important mode of failure in the lower continental crust field relations show that granulite facies rocks can exist in a metastable state under eclogite facies conditions and imply that the lower crust can host differing metamorphic facies at the same depth deformation of granulite and partial conversion to eclogite such as is exposed on holsnoy island may be an orogenic scale process in the lowermost crust of collisional orogens

oxygen isotope equilibrium between eclogite minerals and its constraints on mineral sm nd chronometer abstract sm nd and oxygen isotope analyses were carried out for mineral separates of ultrahigh pressure eclogites from the sulu terrane in eastern china the results show a direct correspondence in equilibrium or disequilibrium state between the oxygen and sm nd isotope systems of eclogite minerals the omphacite garnet pairs of oxygen isotope equilibrium at eclogite facies conditions yield meaningful triassic sm nd isochron ages whereas those of oxygen isotope disequilibrium give non triassic ages of geological meaninglessness this can be reasonably interpreted by the fact that the rates of oxygen diffusion in garnet and pyroxene are lower than or close to those of nd diffusion and thus attainment of isotopic equilibrium in the omphacite garnet o system suggests achievement of nd isotope equilibrium in the same mineral pairs the presence or absence of fluid in the eclogite protoliths is a major rate controlling factor for isotopic equilibration during high grade metamorphism it appears that the state of oxygen isotope equilibrium between cogenetic minerals can provide a critical test for the validity of the sm nd mineral chronometer in addition the exact timing of the ultrahigh pressure metamorphism in the dabie sulu terranes is constrained at early triassic rather than late triassic

pile and penetrometer end bearing resistance in two layered soil profiles the paper examines the influence of soil strength and stiffness on the end resistance mobilised by a cone or displacement pile in a two layered soil profile i e strong soil overlying or underlying weak soil the investigation involved a series of numerical analyses that idealise pile cone penetration assuming the spherical cavity expansion analogue it is shown how the end resistance mobilised by a penetrometer in a dense sand i e strong soil varies with the number of penetrometer diameters d from a weak soil assumed here to be either a loose sand or soft clay and depends on the ratio of the steady state penetration resistances of the strong and weak layers the penetrometer resistance in the weak soil is not affected by an adjacent strong layer at penetrations greater than 2d a design procedure based on a numerical parametric study is proposed and this is subsequently shown to compare well with centrifuge test data and with previous numerical research

mineral fluid melt interactions in high pressure shear zones in the bergen arcs nappe complex caledonides of w norway implications for the fluid regime in caledonian eclogite facies metamorphism abstract felsic extension veins consisting of plagioclase ab 91 phengite quartz clinozoisite and minor accessory calcite occur in the central parts of caledonian eclogite facies shear zones at holsnoy island in the bergen arcs nappe complex the veins have the field and textural characteristics of syntectonic intrusions and have crystallized at pressures and temperatures compatible with the peak of eclogite facies metamorphism ca 700 c 16 19 kbar the quartz contains early primary fluid inclusions of a aqueous brine 31 34 wt nacl and b a co 2 n 2 mixture with x n 2 5 mole percent the two fluids were present simultaneously and are interpreted as immiscible at the pt conditions of vein formation later generations of fluid inclusions comprise nitrogen rich co 2 n 2 mixtures and aqueous fluids with low salt contents the latter were trapped at a late stage of the cooling and uplift history of the nappe complex at the temperature of the peak of eclogite facies metamorphism at holsnoy ca 700 c introduction of a fluid phase with high water activity caused partial melting of the surrounding mafic to intermediate lithologies the muscovite granite extension veins represent the crystallization products of anatectic melts migrating through the shear zones at eclogite facies conditions

analysis of the mahuika comet impact tsunami hypothesis abstract a comet impact on february 13 1491 ad 250 km sw of new zealand named mahuika has been proposed as the tsunamigenic source for an alleged large 15th century tsunami along the new zealand and east australian coastlines this hypothesis has been based on astronomic and atmospheric evidence and data from near the putative impact site but the underpinning documentation has never been fully presented we outline the current mahuika comet impact tsunami hypothesis and analyse the original data sources geophysical evidence for a crater has never been documented tektites are widespread in south pacific sediments and provide no indication of the event age and far field evidence for any comet impact in the 15th century is unconvincing all the evidence reviewed indicates that no comet mahuika or otherwise struck the earth on february 13 1491 ad based upon our reassessment the origin of apparent tsunami deposits along the coasts of new zealand and east australia needs to be reassessed they are not tsunami deposits the mahuika comet impact tsunami hypothesis should be treated with extreme caution until stronger evidence is presented

a release to rest model for dynamically installed anchors abstractdynamically installed anchors are torpedo shaped anchors that are installed by dropping them through the ocean such that they self bury in the soft seabeds typically encountered in deep wat

calibration chamber tests of a cone penetrometer in sand the results of a series of tests using a cone penetrometer in sand in a large calibration chamber are reported sand at three different densities and a range of stress states was studied the principal finding from the tests is that cone resistance in sand depends primarily on the horizontal stress and the angle of friction but is relatively unaffected by the vertical stress a relationship between qc h and tc is proposed and compared with previous work in calibration chambers l article presente les resultats d une serie d essais effectues avec un penetrometre a cone dans du sable dans une chambre d etalonnage le sable a ete etudie avec trois densites differentes dans un intervalle d etats de contrainte les essais ont demontre surtout que la resistance au cone dans le sable depend d abord de la contrainte horizontale et de l angle de friction mais reste relativement peu influencee par la contrainte verticale on propose une relation entre qc h et tc et on la compare avec des recherches anteri

bearing capacity and stiffness of embedded circular footings on stiff over soft clay abstractthis technical note presents results from a series of undrained load tests performed at model scale on circular embedded footings founded in a two layered stratigraphy comprising uniform s

effects of pile shape and pile end condition on the lateral response of displacement piles in soft clay a series of lateral tests conducted in a centrifuge on displacement piles in kaolin is used to examine the effects of pile shape pile end condition and clay overconsolidation on the lateral load t

rate effects on the vertical uplift capacity of footings founded in clay this paper describes results from a series of uplift tests performed in a drum centrifuge on shallow square footings founded on clay and sand with an overlying sand backfill the test series investigated footings of various widths loaded at displacement rates extending over five orders of magnitude additional tests were performed to examine the influence on uplift capacity of the direction of load inclination the uplift tests performed on footings founded on sand enabled estimations to be made of the suction that developed at the base of the footings founded on clay it is shown that the suction mobilised at very fast rates may be assessed using existing undrained bearing capacity approaches and a rate corrected operational undrained strength similar to that measured in triaxial extension the uplift rates required to reach fully undrained conditions are almost two orders of magnitude higher than those for footings loaded in compression and the upward footing displacements required to generate maxim

strength of fine grained soils at the solid fluid transition deepwater offshore oil and gas developments require an assessment to be made of the risk of infrastructure damage from submarine slides the likelihood and magnitude of submarine slides and the co

a tem study of disequilibrium plagioclase breakdown at high pressure the role of infiltrating fluid high pressure metamorphism 600 c 20 kbar of the allalin gabbro western alps resulted in the breakdown of plagioclase an63 to fine grained zoisite jadeite kyanite and quartz in rare cases this reaction failed to reach completion the resulting textures of partial reaction have been studied by transmission and analytical electron microscopy in localised regions of a plagioclase crystal where the extent of reaction is 10 only zoisite developed and the orientation relationship left 100 right text zo left 101 right text p1 1 and left 012 right text zo left 010 right text p1 1 is frequently present in regions where 10 50 of plagioclase has transformed the reaction plagioclase h2o zoisite kyanite quartz nasica 1al 1 pl has occurred the systematic orientation relationship between plagioclase and zoisite is absent at 50 transformation complete breakdown of plagioclase occurred in localized micron scale domains by the reaction plagioclase h2o zoisite jadeite kyanite quartz and the reaction products are variably orientated with respect to each other incomplete reaction together with the concentration of reaction products around cracks in original plagioclase grains suggests that extent of reaction was controlled primarily by the availability of h2o the textural observations are interpreted in terms of two possible disequilibrium reaction models 1 plagioclase persists metastably with its original igneous composition to a pressure 17 kbar at 600 c reaction to the equilibrium assemblage then develops adjacent to cracks in response to the presence of aqueous fluid at intracrystalline sites only partial reaction occurs because jadeite and sometimes kyanite and quartz fail to nucleate for kinetic reasons 2 localized regions of a plagioclase crystal partially equilibrate at several stages during the increase of pressure 9 17 kbar at 600 c possibly due to discrete episodes of fluid infiltration in both these models the extent of reaction may be limited by nasi caal interdiffusion in plagioclase

effects of reconsolidation time on holding capacity of deepwater dynamically installed anchors a dynamically installed anchor dia is a practical and promising type of anchor for deepwater offshore engineering currently very few research studies have reported the effects of reconsolidatio

interpretation of cone penetration testing in silty soils conducted under partially drained conditions abstractthe standard penetration rate used in cone penetration tests cpts is 20 mm s regardless of soil type which yields fully drained penetration in sand and fully undrained penetration in clay however for silty soils that represent an intermediate grain size composition and unique characteristics compared with sand and clay the standard rate of penetration results in partially drained penetration often leading to misinterpretation of this soil type in this study 15 cpts with penetration rates varying from 0 5 to 60 mm s were performed at a test site in northern denmark where the subsoil consisted primarily of sandy silt with clay bands the results illustrated that when the penetration rate is reduced the cone resistance increases but the pore pressure decreases the transition between undrained and fully drained penetration was determined by converting the results into a normalized penetration rate also evaluated and presented in this paper is how cone resistance obtained under parti

early tertiary eclogite facies metamorphism in the monviso ophiolite although crucial for the construction of tectonic models of the alps the timing of high pressure metamorphism is still poorly determined and controversial it is likely to vary from one tectonic unit to another depending on when each became involved in subduction this in turn relates to palaeogeographic position with respect to the active ocean basin well defined reliable geochronological data are too few to test this hypothesis this paper extends the database by determining sm nd mineral isochrons on two samples from the monviso ophiolite in the piemonte zone carefully selected to minimize the problems of sm nd dating of eclogites encountered elsewhere in the alps the dated samples have eclogite facies mineral assemblages typical of the lago superiore unit of the ophiolite mineral compositions are similar to previously reported samples and indicate pressures of around 2 gpa and temperatures of 400 500 c sm nd isochron ages of 60 12 and 62 9 ma are defined by garnet and clinopyroxene while the rb sr age on phengite which is part of the high p assemblage is 40 1 ma the new data fit an emerging pattern of ages in which high p metamorphism in the oceanic realm is early tertiary with slightly older ages in the overlying sesia zone and younger oligocene ages in the underlying internal basement massifs which only became involved in subduction when closure of the piemont ocean was complete

shear deformation and eclogite formation within granulite facies anorthosites of the bergen arcs western norway the anorthosites of the bergen arcs contain two distinct metamorphic mineral assemblages which are stable under different p t conditions a granulite facies assemblage which equilibrated at t 800 900 c p 10 kbar is defined by the minerals plagioclase al rich diopside cpx i garnet gnt i scapolite orthopyroxene dark brown hornblende this assemblage is linked by corona structures to a primary magmatic mineralogy where coexistence of olivine and plagioclase limits the maximum crystallization pressure of the anorthosites to 8 kbar at 1200 c the anorthosites are transected by a series of fine grained shear zones in which the granulite facies assemblage is replaced by an eclogite mineralogy defined by omphacite cpx ii jd40 50 garnet kyanite epidote clinozoisite phengite quartz amphibole with plagioclase sometimes remaining in the marginal parts mineral compositions indicate equilibration conditions for the eclogite paragenesis of t 700 800 c p 16 19 kbar a series of textural and mineralogical changes which can be observed as the strain increases into the shear zones demonstrates that the eclogite mineralogy is formed at the expense of the granulite facies minerals during the early stages of shear zone development the eclogite mineralogy defines a strong mylonitic fabric which again is truncated by centimetres thick secondary shear zones containing clasts of both granulite and eclogite minerals these latter fine grained ultramylonites may be connected to uplift of this deep seated complex the eclogite shear zones are highly oblique to the granulite structures indicating that the eclogite shear zones formed under a new stress regime rb sr dating shows that the granulite facies assemblage formed in sveconorwegian time or earlier while minerals from shear zones define ages around 400 ma indicating a caledonian formation of the eclogites this work demonstrates the critical role of deformation in triggering metamorphic reactions whether the shear stress also was important in stabilizing the eclogite assemblages is not clear from the available data

constraints on element mobility associated with the conversion of granulite to eclogite along fractures in an anorthositic complex on holsnoy norway on holsnoy an island off the coast of western norway an anorthositic complex metamorphosed to granulite facies was partially overprinted by a later eclogite facies metamorphism eclogite facies rocks containing omphacite garnet kyanite and hydrous phases such as mica and zoisite occur in shear zones of various scales and adjacent to veins previous studies of shear zones on holsnoy reported evidence for substantial element mobility jamtveit et al 1990 mattey et al 1994 in this work we compare chemical compositions of granulite and its undeformed eclogitized equivalent adjacent to veins in locations where a single band of granulite can be traced and sampled as it approaches the vein this tracing is crucial because the pre granulite rocks cover a substantial compositional range indicative of a petrologically variable protolith consisting of anorthosite gabbro and jotunite we analysed multiple core samples collected across nine separate granulite eclogite transition zones located at veins in anorthositic jotunitic and gabbroic protoliths for major and trace elements for each transition no compositional difference between the average granulite and average eclogite composition was found at the 90 confidence level except for loi loss on ignition which was consistently significantly higher in the eclogite samples although not significant at the 90 confidence level for any single traverse the average eclogite concentrations of sio2 na2o cs as and br exceed the average granulite concentrations for eight or all nine of the traverses for most traverses statistical analysis of the data limits any gain of sio2 in the eclogites to no more than a few relative per cent other than the introduction of volatile substances presumably an h2o rich fluid eclogitization associated with vein formation was essentially isochemical

metastability of granulites and processes of eclogitisation in the uhp region of western norway the flatraket complex a granulite facies low strain enclave within the western gneiss region provides an excellent example of metastability of plagioclase bearing assemblages under eclogite facies conditions coesite eclogites are found 28 kbar unprecedented metastability of plagioclase and quartz is implied alternatively a tectonic break exists between the flatraket complex and uhp eclogites supporting the concept of a tectonic boundary to the uhp zone of the western gneiss region the distribution of eclogite and amphibolite facies metamorphic overprints demonstrates that the reactivity of the crust during deep burial and exhumation is strongly controlled by fluid availability and is a function of the protolith

discrete element model dem simulations of cone penetration test cpt measurements and soil classification this paper presents a study on the simulation of cone penetration tests cpts using the discrete element model dem method this study s main objective is to investigate the effect of different m

shallow penetrometer tests theoretical and experimental modelling of the rotation stage shallow penetrometers are a new type of device that measures the properties of surficial offshore sediments via multi phase tests involving penetration dissipation and rotation stages in fine gr

dynamic analysis of a smooth penetrometer free falling into uniform clay the finite element analysis of free falling objects penetrating soil deposits is one of the most sophisticated and challenging problems in geomechanics a robust numerical method will be described here for dealing with such complex and difficult problems the approach is based on the arbitrary lagrangian eulerian ale method of analysis the main features and challenges of which are described briefly in the paper the ale method is then employed to perform a parametric study of a perfectly smooth penetrometer free falling into a uniform layer of clay which deforms under undrained conditions the effect of the mechanical properties of the clay soil on the penetration characteristics is presented and an approximate closed form expression is derived for the dynamic penetration factor ndp comparisons are made between the deduced values of ndp and published values of the conventional cone factor nc and comparisons are made with experimental data to validate the approach

estimation of soil strength in fine grained soils by instrumented free fall sphere tests the dynamic response of a sphere in soft clay is considered through field tests in which a 0 25 m dia steel sphere was allowed to free fall in water and dynamically penetrate the underlying soft soil the test data collected in a lake and a sea environment relate to sphere velocities of up to 8 m s reaching sphere invert embedments close to ten diameters an inertial measurement unit located within the sphere measured the motion response of the sphere during free fall and penetration in soil the resulting acceleration data were used within a simple framework that accounts for both geotechnical shearing resistance and fluid mechanics drag resistance but cast in terms of a single capacity factor that can be expressed in terms of the non newtonian reynolds number the merit of the framework is demonstrated by using it as a forward model in a series of inverse analyses that calculate the undrained shear strength profile from acceleration data measured in free fall sphere tests the good match between th

fine scale isotopic heterogeneities and fluids in the deep crust a40ar 39ar laser ablation and tem study of muscovites from a granulite eclogite transition zone spectacular exposures on holsnoy island western norway reveal that eclogites formed in situ from adjacent anhydrous granulites as a result of the localized infiltration of fluids stepwise and laser40ar 39ar experiments on muscovite from the eclogites have been used in conjunction with electron microprobe and transmission electron microscopy tem analysis to examine the behavior of argon under high pressure metamorphism and subsequent cooling muscovites with 0 10 0 17na na k yield40ar 39ar plateau and integrated ages in the range 450 465 ma 20 35 myr older than40ar 39ar muscovite plateau ages from adjacent eclogite samples laser40ar 39ar analyses on 75 m spots across two single muscovite grains from these samples are approximately uniform at 444 2 1 9 21 spots and 443 3 1 7 ma 26 spots however incremental heating of high sodic 0 18 0 32 na na k muscovite failed to yield a plateau laser40ar 39ar analyses of 100 areas from two single grains from this sample reveal complex two dimensional patterns with variable apparent ages in the range of 445 625 ma electron microprobe measurements obtained from one of the grains reveal that the paragonite content is also highly variable both parallel and perpendicular to 001 all the tem bright field images obtained from this mica yield information consistent with a single homogeneous phyllosilicate phase yet several of the selected area electron diffraction saed analyses document locally intergrown muscovite and sodic muscovite possibly in an exsolution relationship on a unit cell scale analytical electron microscopy aem analyses obtained over a 5 100 nm scale on the same sample reveal great range and heterogeneity inna k including pure muscovite although no separate paragonite domains were found in contrast muscovite grains with consistent laser spot fusion and plateau ages show little heterogeneity inna k at the microprobe level these data provide evidence of variable fluid mediated incorporation of excess40ar under high pressure eclogite facies conditions at the time of the development of the sodic muscovite compositions the data indicate that fine scale heterogeneities in argon isotopic compositions were generated during eclogite facies equilibration and were preserved as the rocks were cycled back to the surface despite the influx of free fluids in the rocks at high pressure the heterogeneities are best reconciled with local buffering and limited mobility of the fluids at least during the final stages of equilibration

effect of perforations on uplift capacity of skirted foundations on clay the retrieval of deep water subsea installations resting on soft soil such as mudmat shallow foundations can be a difficult and costly operation if significant resistance to uplift is experienc

relating shaft friction of buried piles and cpt resistance in clayey sands this paper examines factors controlling the ultimate shaft friction developed on buried piles in normally consolidated clay sand mixtures and explores the relationship between this friction and the

sm nd disequilibrium in high pressure low temperature himalayan and alpine rocks in order to decipher the causes of sm nd isotopic disequilibrium in high pressure low temperature rocks sm nd isotopic analyses were carried out on minerals from four himalayan tso morari unit and four alpine dora maira monte viso sesia lanzo eclogitic rocks of different lithologies and different intensities of post eclogitic metamorphism in most of these

some measurements of the permeability of kaolin this paper reports an experimental investigation of the vertical and horizontal permeabilities of speswhite kaolin clay the permeabilities were measured using falling head permeability tests a mo

rate effects on penetrometer resistance in kaolin this paper describes the results from a centrifuge investigation into the rate dependence of t bar and ball penetrometer resistance in kaolin four t bar diameters and two ball diameters were installed in kaolin with overconsolidation ratios of 1 2 and 5 at penetration velocities varying over five orders of magnitude the penetration resistances are compared with the properties of kaolin as measured in element tests to assist in the development of a framework that describes this resistance over the full velocity range consistent trends emerge when the soil viscosity is assumed to affect the penetration resistance in both the partially drained and undrained conditions enabling the dependence of the t bar and ball resistances on diameter velocity and soil characteristics to be quantified

micro scale element migration during eclogitisation in the bergen arcs norway a case study on the role of fluids and deformation abstract understanding chemical element mobility during high pressure metamorphism is paramount to the knowledge of the transformations occurring during the course of eclogite facies metamorphism in particular the role of deformation and fluid circulation appear essential in order to better decipher this role we investigated two eclogite facies samples from the lindas nappe in the bergen arcs norwegian caledonides which are related to a fluid deformation metamorphic event this study based on detailed microtextural investigations coupled with major and trace element analyses either in situ empa and la icp ms or by conventional icp ms nebulisation on mineral fractions illustrates the complexity of chemical reactions accompanying the eclogite and amphibolite facies metamorphism a single eclogite facies mineral species two eclogite facies i e phengite and epidote depicts various chemical features depending on its textural location at thin section scale the correlation with the mineralogical reaction occurring in each textural site demonstrates that the compositional variations are inherited from the precursor minerals thus the composition of eclogite facies minerals is locally controlled by the composition of few hundred micron domains on the contrary alteration phases of the amphibolite facies symplectite and calcic amphibole display clear enrichment in lile pb sr and lree compared to their precursor minerals omphacite and garnet this supports that the transport of elements at hand sample scale was enhanced during the retrogression and elements were efficiently delocalised from one textural site to another the contrasting behaviour of element mobility between peak eclogite facies metamorphism and retrogression can be explained in terms of rate processes and fluid deformation activity during eclogitisation deformation allows the formation of textural and mineralogical microdomains contemporaneously the fluid circulation favours the development of heterogeneities by transport of elements in excess towards areas protected from deformation where phengite bearing quartz lenses crystallise this together with the very fast recrystallisation of eclogite facies minerals results in a heterogeneous redistribution of elements at sample scale and in a chemical disequilibrium between different microdomains of hundred micron size during retrogression in the amphibolite facies coeval with long term ductile deformation the fluids act as an efficient vector to redistribute the elements from a given textural site to another and thus allow to reach at hand sample scale a new chemical equilibrium between the different crystallising phases

analysis of piezocone penetration under different drainage conditions with the two phase material point method abstractthe piezocone penetration test cptu is commonly used to identify a soil s profile and estimate its material properties depending on the soil type ranging from clay to sand undrained partially drained or drained conditions may occur during cone penetration in silt and sand clay mixtures the cptu penetration is characterized by partially drained conditions which are often neglected in data interpretation the effect of drainage on cptu measurements has been mainly studied experimentally numerical analyses are rare because taking into account large soil deformations soil water and soil structure interactions and nonlinear soil behavior is still a challenging task this paper presents and discusses numerical simulations of cptu in saturated soils with the two phase material point method soil behavior is described with the modified cam clay model this study investigates the effects of pore pressure dissipation during penetration cone roughness and horizontal stress state comparing the