identifying uncertainty in estimates of bimrocks volumetric proportions from 2d measurements abstract chaotic geological bodies composed of rock inclusions of different lithology and size enclosed in a weaker matrix are often referred to as bimrocks block in matrix rocks when dealing with these challenging and widespread geomaterials a major concern for geopractitioners is the estimation of block content which has been demonstrated to strongly affect the overall mechanical behaviour of bimrocks since the estimation of this parameter is not a simple matter stereological principles are generally applied to infer 3d block contents from 1d or 2d measurements however they are often fraught with a high magnitude of error in this study a statistical approach was developed to determine the uncertainties associated with estimates of the 3d block proportions from 2d measurements a matlab code was implemented to generate heterogeneous models with a size distribution typical of bimrocks an uncertainty factor is provided related to the size of the outcrop area investigated and the 2d block content to adjust the initial 2d estimates it was found that a larger investigation area increases the reliability of the 2d measurements and as actual volumetric block proportion increases the uncertainty decreases the results obtained through this procedure were subsequently compared with previous findings from the literature concerning the uncertainty in estimates of the vbp from 1d measurements the outcome of this comparison highlights the strength of the procedure described in this paper

mesoscale oceanographic processes beneath the ice of fram strait a major component of the fram strait marginal ice zone experiment was the investigation of air sea ice interactions processes and circulation patterns found behind the local ice edge and on scales greater than 10 kilometers mesoscale and large scale neutrally buoyant floats ice tethered cyclesondes and helicopter based measurements were used to obtain uniquely integrated and consistent views of the mesoscale ocean features beneath the ice cover of fram strait within the vicinity of the yermak plateau three distinct regions of mesoscale motion were observed that coincided with the shallow topography of the plateau the northward flowing atlantic water over the western flank of the plateau and the strong current shear zone of the east greenland polar front a subice meander of the front was also observed which was probably occluded subsequently

an inverse modeling study in fram strait part i dynamics and circulation abstract in order to reconstruct the circulation in the northern greenland sea between 77 n and 81 n and the exchanges with the arctic ocean through fram strait a variational inverse model is applied to the density field observed in summer 1984 during the mizex 84 experiment an estimate of the three dimensional large scale pressure field is obtained in which the solution is decomposed into a limited number of vertical modes and the mode amplitudes are described by piece wise polynomials on a finite element grid the solution should be consistent with a frictional depth integrated vorticity balance and with the density data the global model parameters are tuned to ensure agreement between the retrieved geostrophic velocity and independent currentmeter data in a companion paper schlichtholz and houssais 1999b the same method but without dynamical constraint is applied to the same hydrographic dataset to perform a detailed water mass analysis and to estimate individual water mass transports a comprehensive picture of the summer geostrophic circulation in fram strait is obtained in which northward recirculations in the east greenland current egc and various recirculations from the west spitsbergen current wsc to the egc are identified it is suggested that the branch of the wsc following the upper western slope of the yermak plateau turns westward beyond 81 n and recirculates southward along the lower slope then merging with a westward recirculating branch south of 79 n at 79 n a southward net transport of 6 5 sv is found in the egc which combined with a northward net transport of only 1 5 sv in the wsc results in a fairly large outflow of 5 sv from the arctic ocean to the greenland sea the inverse solutions show that in summer the local induction of vorticity by the wind stress curl or by meridional advection of planetary vorticity should be small so that in the egc and in the wsc the vorticity balance is mainly achieved between the bottom pressure torque and dissipation of vorticity through bottom friction a substantial barotropic flow associated with along slope potential energy gradients is indeed identified on both sides of the strait

a simple ice ocean model for the greenland sea abstract a steady coupled model of the upper ocean circulation and ice cover in a meridional channel is presented and applied to the greenland sea the main ocean gyre is driven by wind stress however a nonzero boundary condition on meridional velocity is applied at the western side to produce a southward flowing coastal current representative of the east greenland current egc to match the egc to the interior sverdrup solution a munk type western boundary layer is introduced the upper ocean temperature is governed by an advection diffusion equation which is forced at the boundaries and by heat exchange with the atmosphere the ice model is purely thermodynamic and the ice edge position is determined iteratively since the streamfunction and temperature fields depend on the ice cover and in turn the ice cover is determined by both the ocean and air temperature the range of behavior of the temperature field and ice edge position is studied as a function of the ice ocean drag the wind stress tra

influence of temperature on the permeability of rocks changes in physical properties due to temperature increase have been investigated for three generically different types of rock marble sandstone and granite the hg porosity and permeability of the rocks were analysed the permeability of the specimens was determined during axial loading at a constant triaxial state of stress greater permeability changes were registered for rocks with compact structure and low porosity these types of rock are characterised by line contacts between the grains they are more sensitive to temperature increase pores with a radius greater than 500 nm increase due to the temperature influence with the permeability increasing considerably

meteoric diagenesis of plio pleistocene limestones at enewetak atoll abstract petrographic lithologic mineralogic and minor elemental data from plio pleistocene carbonates at enewetak atoll indicate that these sediments have been calcitized in the near surface meteoric diagenetic environment shallow 100 m mostly pleistocene sediments remain aragonite rich with a few discrete meter scale calcite rich intervals developed either at pleistocene soil zones or in thin 5 m paleophreatic lenses deeper 100 to 180 m mostly pliocene sediments are characterized by pervasive calcitization of aragonite extensive dissolution with well developed moldic porosity and the occurrence of isopachous bladed and pore filling equant calcite cements pervasively calcitized pliocene limestones exhibit a narrow range in 18o value 1 0 53 a wide range in 13c value 1 1 63 and low mean sr 0 02 wt and mg 0 25 wt contents these data are most consistent with diagenetic alteration of plio pleistocene carbonates by meteoric phreatic calcitization although in some intervals calcitization in the mixed meteoric marine environment may have also occurred petrographic data document the superposition of subaerial exposure surfaces a d paleophreatic lenses in the subsurface of enewetak sr isotope data and stratigraphic forward modeling are consistent with the multiphase meteoric phreatic calcitization of pliocene limestones in response to subaerial exposure shortly after sediment deposition and during pleistocene sea level lowstands quantitative water rock interaction modeling of whole rock chemical trends suggests that calcitization occurred in an open diagenetic system at water rock w r volume ratios of 103 to 105 proxy indicators of climate e g retention of aragonite at depth and the development of caliche at subaerial exposure surfaces are consistent with an arid to semi arid plio pleistocene climate moreover a limited supply of meteoric waters in the vadose environment despite vertically and temporally extensive paleovadose environments is consistent with limited calcitization of the pleistocene sequence alternatively previous estimates of the rates of vadose calcitization may be too high to be applicable at enewetak stratigraphic shortening of the plio pleistocene sequence in response to carbonate dissolution during atoll emergence is not consistent with available data

the formation of polar surface water the ice export and the exchanges through the fram strait abstract the polar surface water is formed from two parent water masses inflowing atlantic water and fresh from river run off and net precipitation two possible modes for this formation are considered 1 a entrainment driven by mechanical stirring takes place over the entire polar ocean and brings atlantic water into the surface layer 2 b the interaction between the atlantic water and the fresh water supply occurs only on the s shelves while the mixing in the interior is inhibited by a thick advective layer of intermediate density formed on the shelves the exchanges between the polar ocean and the north atlantic and the resulting stratification are determined for the two cases the derived transports are much smaller than those often encountered in the literature which mode dominates depends upon the fresh water discharge from the analysis it is found that a larger fresh water contribution favours mixing on the shelves while the entrainment in the interior becomes more important as the run off diminishes the present day situation is probably one where the shelf processes dominate however a modest decrease in the river run of the ocean it is found that a complete removal of the river run off may not affect the extent of the ice cover too seriously so that comparatively high ice export can be maintained this is because the higher salinity of the polar surface water gradually increases the fresh water buffer present in the pacific inflow

banktop responses to quaternary fluctuations in sea level recorded in periplatform sediments periplatform sediment from a 12 m core recovered from northwest providence channel bahamas contains a geochemical and paleontological record of sea surface temperatures ice volumes and the response of banktops to highstands of sea level a comparison of these data suggests that fluctuations of carbonate mineralogy in periplatform sediments result from fluctuations of sea level and from patterns of banktop sedimentation highstands of sea level that flood carbonate platforms are recorded in periplatfonn sediments as abrupt increases of exported sr rich aragonite derived from banktop orgiuiisms superposed on a background of sr poor aragonite pteropods and calcite foraminifera and coccoliths derived from planktonic sources the pulses of banktop sediment coincide with increases of water temperature determined from foraminiferal assemblages and with decreases in ratios of oxygen isotopes indicating decreased ice volume and rising sea level following these abrupt changes is a more gradual decline in bank derived sediment although paleotemperatures from foraminiferal assemblages and oxygen isotopic data clearly show that warm conditions and a highstand of sea level persist we suggest that this decrease of offbank transport is part of autocyclic sedimentation patterns of shallow water carbonate environments offbank transport is restricted as reefs sand shoals and islands reach sea level also green algal production may decline because progradation of tidal flats decreases lagoon area and the hydrologic and ecologic conditions change as lagoons are filled

influence of the interval length of hydraulic packer systems on thermally induced pore pressure measurements in rock abstract during the past several decades hydraulic packer systems have generally been used to measure the thermally induced pore pressures in many in situ experiments in nuclear waste management programs the measured value using hydraulic packer system is a combined value of the pore pressures in the rock along the packer interval and not the pore pressure at the middle point the suitability of using the packer system measured value to represent the thermally induced pore pressure at the middle point of the packer interval needs to be assessed the accuracy of using hydraulic packer systems is examined in this paper using a coupled thermal hydraulic mechanical thm model for fully saturated conditions developed using the finite element program comsol the results indicate that there could be large errors in the measured values with the size of the error dependent on the size of the packer interval the variation of pore pressure gradient along that interval and the orientation of the packer measurement borehole to improve the accuracy of the measurement using packer systems the variation in pore pressure gradient along the packer interval should be small or if a substantial gradient variation is expected the length of the packer interval should be made as small as possible a packer interval with a length less than 0 5 m is suggested if a packer system has been installed with a large interval length in a location where a large pore gradient variation may exist calibration of any associated numerical model using this measurement should incorporate the packer measurement system the numerical results of this coupled thm model are in good agreement with the integration of a point heat source theoretical solution throughout the heater line

analysis of thermally induced changes in fractured rock permeability during eight years of heating and cooling at the yucca mountain drift scale test analysis of thermally induced changes in fractured rock permeability during eight years of heating and cooling at the yucca mountain drift scale test j rutqvist 1 b freifeld 1 k b min 2 d elsworth 2 y tsang 1 earth sciences division lawrence berkeley national laboratory ms 90 1116 berkeley ca 947 20 usa department of energy and geo environmental engineering pennsylvania state university university park pa 16802 usa corresponding author tel 1 510 486 5432 fax 1 510 486 5432 e mail address jrutqvist lbl gov j rutqvist abstract we analyzed a data set of thermally induced changes in fractured rock permeability during a four year heating up to 200 c and subsequent four year cooling of a large volume partially saturated and highly fractured volcanic tuff at the yucca mountain drift scale test in nevada usa permeability estimates were derived from about 700 pneumatic air injection tests taken periodically at 44 packed off borehole intervals during the heating and cooling cycle from november 1997 through november 2005 we analyzed air permeability data by numerical modeling of thermally induced stress and moisture movements and their impact on air permeability within the highly fractured rock our analysis shows that changes in air permeability during the initial four year heating period which were limited to about one order of magnitude were caused by the combined effects of thermal mechanically induced stress on fracture aperture and thermal hydrologically induced changes in fracture moisture content at the end of the subsequent four year cooling period air permeability decreases to as low as 0 2 of initial and increases to as high as 1 8 of initial were observed by comparison to the calculated thermo hydro elastic model results we identified these remaining increases or decreases in air permeability as irreversible changes in intrinsic fracture permeability

predicting the deformation moduli of rock masses abstract predictive empirical models for the mechanical properties of rock masses have been used in rock engineering because direct measurement of the properties is difficult due to the presence of discontinuities such empirical models are open to improvement because they are based on collected data the purposes of the present study are to assess the existing empirical equations and to develop a new empirical approach for this reason in the first stage of the study the prediction performance of the existing models proposed for predicting the deformation modulus of rock masses were evaluated statistically by using a database including 115 data values obtained from in situ plate loading and dilatometer tests a new empirical approach with higher prediction capacity than the existing empirical models was developed in the subsequent stage of the study the new empirical model considers the modulus ratio of intact rock e i ucs rock quality designation rqd and weathering degree wd although data obtained from very weak and weak rock masses were included in the development of the new empirical equation the type of rocks employed in the study were limited therefore a crosscheck between the new empirical equation and previous empirical approaches should be performed in the design stage

studies of the arctic ice cover and upper ocean with a coupled ice ocean model an ice ocean model has been developed by coupling the hibler ice model to a three dimensional ocean model that consists of a turbulent mixed layer model and an inverse geostrophic model the coupled model has a horizontal grid spacing of 127 km and has 17 vertical levels extending to the ocean bottom the model is forced with 12 hourly general circulation model derived atmospheric fluxes for the year 1986 for which good quality ice edge analyses and buoy tracks were available for comparisons the results are presented for the fifth year of a repetitive simulation with the 1986 fluxes at which time the system has reached a statistical equilibrium the seasonal and geographical variations of the ice cover and the upper few hundred meters of the ocean have been examined including the heat and salt budgets the computed heat fluxes and mixed layer depths mlds fall in the observed seasonal ranges with winter heat fluxes ranging from 15 w m 2 in the central arctic to about 500 w m 2 in the barents sea area and summer fluxes from about 5 w m 2 under the ice to about 30 w m 2 in the various marginal ice zone miz edge areas the corresponding winter mlds are found to be about 25 75 m in the central arctic to a deep 800 m in the greenland sea typical summer mlds are between 5 and 30 m in all seasons the miz was found to be the center of flux activity for both heat and salt with the processes of advection diffusion atmospheric forcing and vertical oceanic fluxes having their largest values here and of comparable magnitudes values of the heat flux components in the miz exceed those found under the ice by an order of magnitude or more and those in the open water region by a factor of 2 for salt the situation is similar except in the summer june through september when a lot of salt flux activity takes place under the ice comparisons are made with naval polar oceanography center npoc analyses for ice concentration and ice edge and with observed arctic buoy tracks in the same 1986 time period the computed ice edge positions have comparable accuracy to previous three dimensional coupled ice ocean studies with too much ice growth during the winter in the barents sea and too little ice east of greenland the ice thickness distributions however are much better with a monotonic increase of the ice thickness from the siberian coast east toward the canadian archipelago with maximum winter values of about 5 6 m

limitations on lowstand meteoric diagenesis in the pliocene pleistocene of florida and great bahama bank implications for eustatic sea level models data from three bahamian and south floridan cores with deeper water facies show that contrary to current models there is no phreatic meteoric diagenesis that can be attributed to large scale sea level lowstands models of meteoric diagenesis in carbonate sediments commonly assume major phreatic alteration during glacio eustatic sea level lowstands however the diagenesis previously attributed to large scale 80 m lowstands is found in shallow water facies that have been repetitively exposed in order to document diagenesis from large scale lowstands an interval is needed that was deposited in deeper water and not immediately exposed to meteoric fluids three cores with such deeper water facies indicate that the majority of phreatic meteoric diagenesis in florida and the bahamas happened during glacio eustatic highstands not during lowstands the data also suggest that diagenetically active meteoric lenses in florida and the bahamas are restricted to within 60 m and perhaps less of the land surface the most likely reasons deeper lenses are chemically inactive are 1 the greater percolation distance allows the water to reach saturation prior to entering the lens and 2 the large distance exceeds the reach of soil derived organic matter known to drive diagenesis in meteoric lenses models that currently assume a constant rate for alteration in meteoric fluids need to accommodate this variation with thickness of the vadose zone this study also questions the use of paleophreatic lenses as records of eustatic sea level as the large scale falls may not leave any record

a model for the thickness and salinity of the upper layer in the arctic ocean and the relationship between the ice thickness and some external parameters abstract this paper presents a dynamical model for the salinity and thickness of the upper layer in the arctic the parameters are the river runoff to the arctic the buoyancy supply through the bering strait the export of ice from the arctic and a parameter characterizing the vertical mixing an ice model is formulated having the following two important properties 1 the horizontal surface area of the exported ice is essentially determined by external parameters the wind field over the arctic and 2 there is a relationship between the ice thickness and the fraction of open water in the arctic the model for the upper layer and the ice model are used together with a heat budget for the arctic also including the effect of different albedo for ice and open water a relationship between the freshwater supply and the ice thickness is derived also investigated are the effects on the ice thickness of a changed export of ice area and changed properties of the flow through the bering strait it is found t

no aridity in sunda land during the last glaciation evidence from molecular isotopic stratigraphy of long chain n alkanes molecular distribution and stable carbon isotopic composition n 13 c of n alkanes determined in a sediment core 17962 from the southern south china sea scs show that no obvious change has taken place in vegetation on sunda land from the last glacial period to the beginning of the holocene a shift in the accumulation rate of longchain n alkanes c27 to c33 was recorded at a depth of about 620 cm probably indicative of precipitation enhancement related to winter monsoon the n 13 c values are within the range of 333 7 to 327 1x for c29 n alkanes and 333 9 to 328 4 for c31 n alkanes in the whole core sequence such an isotopic composition is characteristic of n alkanes biosynthesized mainly by plants utilizing the c3 photosynthetic pathway continuous development of c3 plants on sunda land and its surroundings evidences that the climate during the last glacial period in the southern scs was not drier than what it is today 2003 elsevier b v all rights reserved

laboratory and analytical model studies of the faroe bank channel deep water outflow abstract results are described from a combined laboratory and analytical study of the dense deep water flow through the faroe bank channel archival field data have been used to specify the velocity and density field conditions in an idealized distorted laboratory model in which the spatial and temporal development of a turbulent dense source flow has been studied parametrically in terms of the source rossby and froude numbers respectively measurements are presented to show that the flow i maintains geostrophic balance within the topographically varying channel and ii adjusts on the ekman time scale to changing flow conditions the outflow structure is shown to consist of a dominant axial i e along channel core component with a significant transverse i e side slope secondary circulation driven by ekman drainage and topographic divergence processes density field measurements are presented to show the mixing occurring between the turbulent outflow and the overlying water mass buoyancy an

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

what are the spratly islands abstract seismic records combined with dredged samples and a core indicate that the spratly islands of the dangerous ground province are constructed of presently active carbonate build ups known to extend back continuously at least to the pleistocene and presumed to have initiated in the miocene most likely upon the crests of sea floor cuestas that trend north east south west parallel to the sea floor spreading magnetic anomalies of the contiguous abyssal plain of the southern part of the south china sea the cuestas range from spectacular to subdued constructed of triassic and cretaceous strata and no older rocks have been identified from dredges the cuesta axes plunge towards the south west away from the islands suggesting that the reefs began colonising their more elevated parts but the timing is uncertain the highest seismically recorded cuesta crest is in 440 m of water and the islands and reefs are generally closely surrounded by water deeper than 1500 m since the so called mid miocene unconformity mmu the region has been undergoing post rift thermal subsidence however the nearby seismic lines show no evidence of drowned carbonate reefs it is suggested that the coral algal reefs colonised the crests of the most elevated cuestas that have maintained stability as shown by the 165 m core of one reef indicating periodic exposure with caliche horizons deepening water has protected the build ups from extinction by post rift draping strata in contrast to the central luconia province and the build ups have been able to keep up with regional thermal subsidence the dredged mesozoic strata indicate that the dangerous ground is not exotic and should be interpreted as an integral part of the pre rift sundaland continent that included south china vietnam peninsular malaysia western sarawak and possibly part of sabah igneous and metamorphic samples have been dredged although individual spot k ar dates cannot be accepted at face value such rocks can also be interpreted as an integral part of sundaland post mmu dredged samples are predominantly deep water calcareous mudstones typified by the draping strata of the ocean drilling program odp site 1143 cored from recent to late miocene

late quaternary environments of the carpentaria basin australia abstract quaternary variations in the level of the sea have exposed the shallow 29 000 km2 but shallow maximum depth s 4 0 kyr the pollen assemblages closely resemble the black soil plains presently found along the southern gulf thus the biogeographic and climatic barrier across the australia papua new guinea land bridge has remained largely intact in spite of the range of environmental conditions that have occured during the last

laboratory model studies of mediterranean outflow adjustment in the gulf of cadiz results are presented from a series of laboratory modelling studies carried out as part of the international multidisciplinary project canigo the focus of interest has been the phenomenon of flow adjustment within the gulf of cadiz of the mediterranean outflow plume modelled by a turbulent negatively buoyant jet discharging into a rotating stratified reservoir scaled to the idealised topography of the gulf the results show that the fully developed flow pattern that forms close to the entrance to the gulf consists of a relatively intense jet that divides when it encounters the southern iberian coastal boundary part of the jet is deflected westwards to form a boundary current at intermediate depth along the coastline and part is deflected eastwards and back towards the strait to form a closed weak circulation near the diverging right wall of the gulf within this closed circulation the typical horizontal dimensions of which scale with the source froude number when normalised with the inertial radius small scale eddy features are embedded the degree of entrainment into the descending turbulent jet is seen to be determined primarily by the receiving water froude number and is relatively insensitive to the burger and rossby numbers of the flow resulting in the formation of a boundary current of intermediate density that follows the iberian coastal boundary with a typical velocity determined primarily by the effective driving head at the source and weakly by the burger number of the flow

response of western pacific marginal seas to glacial cycles paleoceanographic and sedimentological features abstract this paper reviews the recent progress in late quaternary studies in five northwestern pacific marginal seas especially the south china sea as an example a series of marginal seas separate asia from the pacific ocean and significantly modify the material and energy flux linkage between land and sea during glacial cycles the sea level induced environmental signal was amplified in the marginal seas giving rise to drastic changes in areas and configurations of these seas and to reorganization of sea water circulation in basins since most of the western pacific marginal seas are influenced by monsoon circulation and some of these are located within the western pacific warm pool the glacial geographic changes have produced a profound impact on regional and global climate for example the decrease of sea area and sea surface temperature sst in the marginal seas was one of the factors responsible for the enhanced aridity of inland china during the glaciation glacial intensification of the winter monsoon and increased seasonality of sst in marginal seas might explain at least partly the apparent discrepancy between the tropical paleotemperature estimations based on terrestrial and open ocean records in this region as the western pacific marginal seas trap terrigenous material supplied by east asia the deep water sedimentation rates there can be one to two orders of magnitude higher than in the open ocean down slope sediment transport is more active when the sea level changes particularly during the deglaciation at least four types of carbonate cycles have been recognized in the western pacific marginal seas and each of those contains environmental signals from the surface and deep sea water as well as from the drainage basin

seasonal variations of sea ice motion in the canada basin and their implications ice velocities and sea level pressure data from arctic drifting buoys for 1979 85 are used to examine the seasonal variation of sea ice drift in the canada basin a recurring reversal of the mean anticyclonic gyre is demonstrated in late summer in response to changes in atmospheric forcing the identification of this reversal of ice motion is significant for numerical modeling of arctic atmosphere ocean ice interactions

the east greenland polar front in autumn closely spaced salinity and temperature measurements in the region of the east greenland polar front from 75 n to 79 n in october november 1981 are presented the return atlantic current rac having a core of relatively warm and saline atlantic intermediate water aiw t 0 5 to 3 0 c s 34 9 to 35 0 was found everywhere along a steep front separating it from the colder fresher polar water a narrow frontal jet was found to have velocities greater than 0 80 m s where the station density was great enough to resolve its concentrated character notable fine structure was present especially in the warm aiw just east of the front a cold saline water forming a knee in the temperature salinity correlation was present in the upper margins of the rac the knee is formed primarily by warm aiw or atlantic water flowing under the upper layers of water flowing from the arctic ocean calculations are presented to show that an initially isothermal underflow could be modified to a thick thermocline by double diffusion calculations of the rate of cooling of fine structure elements by double diffusion indicate that the fine structure would have a limited lifetime about 12 days if its waters were not continually replenished

an example of estimating rock mass deformation around an underground opening using numerical modeling abstract in rock engineering rock strength is regarded as an important rock mass parameter and it is widely estimated using the uniaxial compressive strength ucs test a ucs test in laboratory requires sampling and preparation of core samples which necessitates time consuming and expensive studies furthermore preparation of cores is almost impossible for a weak rock material taken from foliated laminated or thinly bedded rock masses of low rock quality designation rqd values 0 20 in this case determination of ucs by laboratory test may be impossible in compliance with isrm or astm standards to overcome this difficulty indirect tests such as point load index pli schmidt hammer sh rebound number tests are often employed to predict the ucs however indirect tests are likely to yield ucs values with large standard deviations depending on the geological origin of the rock mass the block punch index bpi has recently been developed to overcome the drawbacks of ucs and indirect tests and to minimize the errors arisen from the structural deficiencies and large standard deviations in this study determination of rock mass behavior in laminated foliated bornova melange yellowish brown flysch and grayish black flysch and well jointed yamanlar volcanics altindag formation where the second phase of the izmir metro tunnels was excavated is aimed the bpi ratings were directly used in rmr calculations and indirectly used to estimate the ucs values of rock materials then the obtained results were input into numerical models along with the rock mass strength ucs rm and deformation modulus of rock mass e rm the results obtained from the numerical models agreed with that obtained results from inner tunnel convergence and ground settlement measurements

thermal strain in a water saturated limestone under hydrostatic and deviatoric stress states abstract the present study is aimed at investigating the evolution of thermally induced bulk strain in a water saturated limestone blaubeuren at three different stress states three cylindrical rock samples are respectively loaded to a constant stress state 1 3 15 mpa 1 45 mpa 3 15 mpa 1 75 mpa 3 15 mpa at drained conditions in a conventional triaxial rock deformation apparatus before the sample temperature is cycled between 30 c and defined levels up to 120 c strain measurements are performed by one circumferential and two axial extensometers irreversible strain in both the lateral and axial sample directions are measured after each temperature cycle indicating permanent increases in diameter and in length the measured bulk strain is separated into different strain components related to 1 initial stress loading 2 reversible thermal expansion and contraction of rock matrix and 3 some residual strain the magnitudes of the residual strain increase with increasing deviatoric stress 1 3 in the lateral direction but decrease with increasing deviatoric stress in the axial direction the derived matrix thermal expansion coefficients range from 6 10 6 c 1 to 1 8 10 5 c 1 and from 9 10 6 c 1 to 1 5 10 5 c 1 respectively in the axial and lateral directions and present lower values at higher deviatoric stresses microstructural analyses evidence tensile cracks which are interpreted to have been induced during the temperature cycles these cracks have the potential to offset matrix thermal expansion yielding lower matrix thermal expansion coefficients at higher deviatoric stresses

mesoscale eddies in the fram strait marginal ice zone during the 1983 and 1984 marginal ice zone experiments during the summer marginal ice zone experiment in fram strait in 1983 and 1984 fourteen mesoscale eddies in both deep and shallow water were studied between 78 o and 81on sampling combined satellite and aircraft remote sensing observations conductivity temperature depth observations drift of surface and subsurface floats and current meter measurements typical scales of these eddies were 20 40 km rotation was mainly cyclonic with a maximum speed in several cases subsurface of up to 40 cm s observations further suggest that the eddy lifetime was at least 20 to 30 days five generation sources are suggested for these eddies several of the eddies were topographically trapped while others primarily formed by combined baroclinic and barotropic instability moved as much as 10 15 km d with the mean current the vorticity balance in the nontrapped eddies is dominated by the stretching of isopycnals accompanied by a change in the radial shear in the most completely observed eddy south of 79on the available potential energy exceeded the kinetic energy by a factor of 2 quantitative estimates suggest that the abundance of these eddies enhances the ice edge melt up to 1 2 km d

equatorial carbonates an earth systems approach the hypothesis here is that an earth systems processes to products approach can be used to better develop predictive models for the recognition and assessment of under evaluated equatorial carbonate systems warm temperatures together with common clastic fresh water and nutrient influx as well as basinal settings in the equatorial tropics all have a major impact on carbonate deposition and diagenesis specific features of equatorial carbonate systems resulting from the combination of processes acting in the region include common occurrence of photoautotrophs and heterotrophs aragonitic and or calcitic dominant mineralogies lack of coated grains or aggregates common associations with clastics lack of associations with evaporites and diversity of platform types including oligophotic ones additional diagenetic characteristics include common micritization and bioerosion paucity of marine cements extensive vadose dissolution and concomitant phreatic cementation there is also significant replacement of aragonite by calcite in regions of meteoric groundwater flow common burial compaction and leaching as well as localized massive dolomitization via sea water or continental derived groundwater flow although equatorial carbonates fall into the warm water photozoan association many of the features described above are at odds with models derived from their warm water arid zone counterparts instead a range of the equatorial carbonate features show some similarities with those formed in cool waters and there have been difficulties separating carbonates from these two very different climatic regimes recommendations for the recognition of phanerozoic regional equatorial carbonate development are i a diversity of calcitic and or aragonitic photoautotrophs plus ii common elements of the heterozoan association plus iii independent for example isotopic evidence for warm temperatures 22 c additional indicators towards a humid equatorial setting are iv situation in appropriate palaeolatitudes v lack of association with sedimentary evaporites coated grain or aggregates and vi geochemical evidence for reduced marine salinity and or nutrient upwelling the aim is that this work will lead to greater awareness and understanding of equatorial carbonate systems and contribute to the development of globally predictive models to better understand past and likely future environmental change

near surface circulation in the northern north atlantic as inferred from lagrangian drifters variability from the mesoscale to interannual 1 the near surface circulation of the nordic seas is basically cyclonic and consists of jets and recirculation cells which are tightly linked to the bottom topography variable forcing by the large scale rotation of the wind leads to a modulation in the strength of the gyres and their interconnecting jets this is seen in drifter and altimeter data currents are stronger during winter and during phases of high north atlantic oscillation index the exchanges between the north atlantic and the nordic seas do not seem to be directly affected by this variable forcing the narrow boundary currents and the intergyre jets are subject to instability causing mesoscale current fluctuations which contribute to the stirring and mixing of polar and atlantic water masses

on a modified arrested topographic wave in fram strait 1 the bottom geostrophic flow in fram strait is explained in terms of a modified arrested topographic wave model the model is based on a combination of the vorticity balance between the topographic vortex stretching and the bottom ekman pumping due to liner friction with a relation between the bottom flow and the bottom pressure gradient over a sloping bottom such a combination emphasizes a dynamical relevance of along isobath density variations at the bottom using an inverse solution based on the hydrographic data from the mizex 84 experiment it is shown that the along isobath bottom density variations should be dynamically important for example in the east greenland current a relatively high correlation between an along isobath distribution of the bottom geostrophic flow and the bottom density is reported for that current the density variations identified in the data should be able to drive a bottom geostrophic flow with a magnitude consistent with the inverse solution and observations

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

biogenic β fabric features in the hard laminated crusts of the mersin and adana regions southern turkey and the role of soil organisms in the formation of the calcrete profiles abstract this paper describes fabric features and their distribution in the calcretes and emphasizes the role of soil organisms in the formation of the calcrete profiles quaternary calcretes are common in the mersin and adana provinces occurring as powdery nodular tubular fracture infill and various forms of crusts the stable isotope values indicate calcrete development under semi arid climatic conditions and a pedogenic origin biogenic or fabric constituents are abundant in the hard laminated crust these are the rhizoliths alveolar septal structures needle fiber calcites calcified filaments spherical calcite bodies microcodium and vadose calcrete pisoliths rhizoliths have mainly formed by the petrification of roots and often contain cellular cortex structures the alveolar septal structure comprises root voids separated by a micritic wall or a bundle of tangentially oriented calcite needles needle fiber calcite is common in the hard laminated crust as monocrystalline rods and polycrystalline needles monocrystalline rods are smooth and small

a diagnostic ice ocean model abstract a coupled ice ocean model suitable for simulating ice ocean circulation over a seasonal cycle is developed by coupling the dynamic thermodynamic sea ice model of hibler with a multilevel baroclinic ocean model bryan this model is used to investigate the effect of ocean circulation on seasonal sea ice simulations by carrying out a simulation of the arctic greenland and norwegian seas the ocean model contains a linear term that damps the ocean s temperature and salinity towards climatology the damping term was chosen to have a three year relaxation time equivalent to the adjustment time of the pack ice no damping however was applied to the uppermost layer of the ocean model which is in direct contact with the moving pack ice this damping procedure allows seasonal and shorter time scale variability to be simulated in the ocean but does not allow the model to drift away from ocean climatology on longer time scales for the standard experiment an initial integration of five years was per

toward establishing a maritime proxy record of the east asian summer monsoons for the late quaternary abstract an astronomically tuned late quaternary planktic foraminiferal 18o record of site md972142 12 41 33 n 119 27 90 e 1557 m water depth in the southeastern south china sea was established the difference in 18o between md972142 and odp792 of the sulu sea is regarded as a maritime proxy of the summer monsoon intensity over the south china sea and southeast asia the profile of this maritime proxy matches well with the summer monsoon index obtained from the terrestrial record of louchuan central chinese loess plateau the amplified planktic 18o signals of the south china sea relative to the sulu sea record are partly caused by the changing intensities of the east asian monsoons at the glacial interglacial time scale throughout the late quaternary

surface freshening in the arctic ocean s eurasian basin an apparent consequence of recent change in the wind driven circulation 1 data collected by an autonomous ice based observatory that drifted into the eurasian basin between april and november 2010 indicate that the upper ocean was appreciably fresher than in 2007 and 2008 sea ice and snowmelt over the course of the 2010 drift amounted to an input of less than 0 5 m of liquid freshwater to the ocean comparable to the freshening by melting estimated for those previous years while the observed change in upper ocean salinity over the melt period implies a freshwater gain of about 0 7 m results of a wind driven ocean model corroborate the observations of freshening and suggest that unusually fresh surface waters observed in parts of the eurasian basin in 2010 may have been due to the spreading of anomalously fresh water previously residing in the beaufort gyre this flux is likely associated with a 2009 shift in the large scale atmospheric circulation to a significant reduction in strength of the anticyclonic beaufort gyre and the transpolar drift stream

a proposal of structural models for colluvial and lateritic soil profile from southwestern brazil on the basis of their collapsible behavior abstract this paper aims to propose structural models for understanding the collapsibility of a colluvial and lateritic soil by conducting oedometric tests with controlled suction executed in laboratory the undisturbed soil samples submitted to experiments were collected by opening a trial pit in experimental field for soil mechanics and foundations situated at the state university of campinas sao paulo brazil the soil samples were characterized by means of standard geotechnical tests chemical and mineralogical tests and mercury intrusion porosimetry oedometric tests with controlled suction showed the influence of matric suction on the compressibility of the soil samples it was also observed that the higher the values of matric suction the higher the laboratory collapse potential cp the mineralogical chemical tests indicated the presence of oxides and hydroxides of iron in the samples compounds usually associated with cementation the presence of mineral such as kaolinite gibbsite hematite and goethite was also observed the impregnated thin layer plates of the soil samples as well as the grain size distribution curves and mercury intrusion porosimetry indicated the presence of a structure formed by microaggregates structural models for soil collapse were proposed basing on the results obtained there were behavioral differences in each soil sample collected at different depths the behavior of the sample collected at a 1 5 m depth was basically influenced by matric suction as for the samples collected at 4 5 m and 6 5 m besides being both influenced by matric suction they were also influenced by the presence of cementing agents samples collected at 4 5 m and by the presence of more angular grains of quartz samples collected at 6 5 m

an estimate of the mean field of arctic sea ice motion the observational basis for our understanding of sea ice motion comes from the trajectories of particular ice floes these ice floes may have been marked by a manned research station or more recently by an automatic data buoy since 1893 almost 100 station years of drift data have been recorded using the principles of optimal linear estimation these data are used to obtain a quantitative estimate of the field of mean motion

eddy near the molloy deep revisited a warm 60 km diameter cyclonic eddy was observed in late summer 1984 in the vicinity of the molloy deep at the eastern edge of the east greenland current depression of isotherms to at least 900 m indicates a deep reaching baroclinicity maximum baroclinic speeds of 0 1 to 0 17 m s are estimated as is a swirl transport of 1 sv

laboratory simulation of exchange through fram strait laboratory experiments and theory were conducted to observe the flow patterns and transport in both buoyancy driven and wind driven rotating fluids in lock exchange experiments water with one density flows into a second basin after a sliding gate is removed water of a second density flows back into the first basin the size and location of the currents for various values of density difference rotation rate and assorted sidewall geometries was recorded volume flux of the fluid was also measured and compared with a theory for lock exchange flow of a rotating fluid in a separate group of experiments with a passive upper layer easterly winds like those in the arctic ocean drive the upper level water into the arctic ocean and therefore oppose the buoyant exchange westerly winds would drive the water out of the arctic ocean this indicates that the exchange between the arctic ocean and the greenland norwegian sea is likely to be driven by buoyancy rather than by driven by wind crude estimates of the volumetric and fresh water exchange rate from the lock exchange formulas are compared with observed ocean fluxes and approximate agreement is found

geomechanical characterization of the miocene cuitzeo ignimbrites michoacan central mexico abstract volcanic rocks especially ignimbrites exhibit complex mechanical behaviours due to their large variation in welding porosity textural and granulometrical characteristics moreover there is a lack of knowledge of how alteration processes affect their intrinsic properties main objective of this research is to characterize the physical mechanical and hydraulic behaviour of different lithofacies of the cuitzeo ignimbrites mexico these volcaniclastic mixtures of lithics and pumice supported by a fine rich matrix are characterized by different textural and granulometric features a general lithostratigraphic section and geological mapping of the study area were accomplished to attain the temporal and spatial distribution of the ignimbrites strength deformation and the failure mode of selected lithofacies were directly related to micro textural and granulometric characteristics by a series of uniaxial and pre and post failure non destructive analyses e g ultrasonic pulse velocity and x ray image tomographies results for four different lithofacies were compared allowing us to explore the variation in the mechanical properties associated with characteristics derived from diagenesis petrophysical properties show that there is a large dependence on the textural characteristics and particularly on the pumice fragments content results derived from laboratory observations and x ray image reconstruction analysis show that the main differences in the average values of porosity are associated to the geometry and morphology of the grains and pore network these are closely related to the stress strength relationship and the mode of failure of each specimen in general the strength for all lithofacies tends to increase linearly with several of the physical properties e g ultrasonic pulse velocity bulk density slake durability tests demonstrate that a large part of the mechanical degradation could be attributed to swelling during wetting drying cycles this decay is significant in lithofacies with groundmass rich in expansible clays

radon and thoron emission from lithophysae rich tuff under increasing deformation an experimental study 1 radon and thoron emissions from lithophysae rich tuff under increasing deformation are measured to determine how mechanical damage affects gas emission levels in tuffs mechanical properties of rocks under stresses should be carefully considered to properly interpret data from geochemical field monitoring two samples are uniaxially loaded up to failure while two others are unloaded at the end of the elastic phase in order to achieve the highest compaction of existing pores changes in the porosity of deformed samples are evidenced by helium pycnometer and microscopy analyses radon and thoron exhalation rates are measured on groups of two samples by alpha spectrometer technique results show that tuff samples are characterised by a dual porosity consisting of a macroporosity given by isolated large pores with sizes from mm up to cm scale and a microporosity ranging between microns to hundreds of microns at the end of the elastic phase pervasive pore collapse is observed due to the closure of the cm scale macropores this is mirrored by a significant decrease of radon and thoron release after failure a further reduction of porosity in the rock adjacent to the fault planes is observed due to extensive closure of both macropores and micropores at this stage radon and thoron emissions increase the formation of new exhaling surfaces is the main carrier of the bulk increase of radon and thoron exhalations strongly prevailing over the densification carried out from the compaction mechanisms in terms of volcanic hazard negative anomalies in radon emissions should be considered as indicators of forthcoming ruptures key words radon and thoron exhalation tuff deformation seismic precursor

variations of connected porosity and inferred permeability in a thermally cracked granite connected porosity volume and throat diameter were measured in granitic samples with different porosity structures heated from 20 to 700 c three types of microstructures are recognized from scanning electron microscopy sem analysis 1 a crack network of transgranular cracks with few intersections 2 a pipe network of intragranular and intergranular tubes with high connectivity 3 a mixed structure of transgranular cracks connected by intragranular tube structures calculations predict a decrease of permeability through crack and mixed networks between 50 and 400 c followed by a sharp increase at higher temperatures the decrease in permeability is associated predominantly with the decrease in throat diameter whereas the increase in both throat diameter and the porosity volume account for the temperature rise only small variations of the permeability are predicted for the pipe network

topographic control of oceanic flows in deep passages and straits saddle points between neighboring deep ocean basins are the sites of unidirectional flow from one basin to the next depending on the source of bottom water flow in these sites appears to be topographically controlled so the interface between the bottom water and the water above adjusts itself to permit bottom water flow from the basin that contains a source of bottom water into the next examples in the atlantic include flow in the romanche fracture zone the vema channel the ceara abyssal plain the anegada jungfern passage and the discovery gap but there are many more theoretical predictions of volume flux using a method that requires only conductivity temperature depth data archives and detailed knowledge of bathymetry near the saddle point are compared with volume flux estimates using current meters and or geostrophic estimates for seven cases the ratio of prediction to volume flux estimate ranges from 1 0 to 2 7 some ocean straits that separate adjacent seas are also found to critically control bidirectional flows between basins theory of the influence of rotation on such critical flows is reviewed predictions of volume flux in eight cases are compared with ocean estimates of volume flux from traditional methods

mineralogical geochemical and isotopic characteristics of quaternary calcretes in the adana region southern turkey implications on their origin abstract calcretes are widespread and form as nodular columnar tubular fracture infill laminated hardpan and conglomeratic crust in the adana region x ray powder diffractometry xrd scanning electron microscopy and energy dispersive analyses sem edx and differential thermal analysis thermal gravimetry dta tg reveal that calcretes and their host rock mudstones are composed predominantly of calcite and smectite respectively the other minerals determined in the samples are palygorskite quartz and feldspar palygorskite is a minor component of the calcretes the inductively coupled plasma atomic emission spectroscopy icp aes analyses reveal that the calcrete samples are characterized by high cao and loi values whereas the host rock mudstones contain relatively high values of sio 2 al 2 o 3 fe 2 o 3 and mgo the cross plots of sio 2 al 2 o 3 cao sio 2 cao mgo and cao fe 2 o 3 show positive and negative correlations their gradual change is due to the degree of the progressive calcretization causing mudstone replacement the 18 o and 13 c values range from 3 8 to 5 7 mean 4 4 and from 7 7 to 10 0 mean 8 6 pdb respectively which are consistent with values of pedogenic calcretes reported in the literature from worldwide sites the 18 o values indicate formation from meteoric water either by replacement or precipitation at estimated temperatures from 21 to 23 c the 13 c values are typical for pedogenic calcretes reflecting development under the c3 dominated vegetation cover and semiarid or seasonally arid climatic conditions

two layer rotating exchange flow between two deep basins theory and application to the strait of gibraltar rotating two layer exchange flow over a sill in a strait separating two relatively deep and wide basins is analyzed upstream of the sill in the deep upstream basin the infinitely deep dense lower layer is assumed to be inactive while the relatively thin upper layer flowing away from the sill forms a detached boundary current in the upstream basin this analysis emphasizes the importance of this upstream boundary current incorporating its width as a key parameter in a formalism for deducing the volume exchange rate and discriminating between maximal and submaximal states hence even for narrow straits in which rotation does not dominate the dynamics within the strait the importance of rotation in the wide upstream basin can be exploited it is shown that the maximal allowable exchange transport through straits wider than 11 2 rossby deformation radii increases as rotation increases unlike for smaller rotations where the exchange decreases as rotation increases the theory is applied to the exchange flow through the strait of gibraltar this application illustrates how images of the oceans taken from space showing the width of the upstream flow in this case a space shuttle photograph might be used to determine the exchange transport through a strait maximal exchange conditions in the strait of gibraltar are predicted to apply at the time the space shuttle photograph was taken

an inverse modeling study in fram strait part ii water mass distribution and transports abstract a water mass analysis is carried out in fram strait between 77 15 and 81 15 n based on three dimensional large scale potential temperature and salinity distributions reconstructed from the mizex 84 hydrographic data collected in summer 1984 combining these distributions with the geostrophic flow field derived from the same data in a companion paper schlichtholz and houssais 1999 the heat fresh water and volume transports are estimated for each of the water masses identified in the strait twelve water masses are selected based on their different origins among them the polar water pw enters fram strait from the arctic ocean both over the greenland slope and over the western slope of the yermak plateau in the atlantic water aw range four modes with distinct geographical distributions are indentified in the deep water range the eurasian basin deep water ebdw is confined to the lena trough and to the molloy deep area where it is involved in a cyclonic circulation the warm and shallower mode of the norwegian sea deep water nsdw concentrated to the west is mainly seen as an outflow from the arctic ocean while the cold and deeper mode essentially observed to the east enters the strait from the greenland sea apart from the ebdw there is a tendency for all water masses of polar origin to flow along the greenland slope the two most abundant water masses the aw and the nsdw occupy as much as 67 of the total water volume the southward net transport of pw through fram strait is about 1 sv at 78 9 n at the same latitude the net transport of aw is southward and equal to about 1 7 sv only the transport of the warm mode aww is northward amounting to 0 2 sv the overall net outflow of the deep waters to the greenland sea is about 2 6 sv two upper water masses the fresh aw f and the cold awc mode of the aw and one deep water mass the nsdw appear to be produced in the strait with production rates between 77 6 and 79 9 n of about 0 2 1 0 and 1 7 sv respectively a southward net fresh water transport through the strait of about 2000 km 3 yr 1 relative to a salinity of 34 93 is mainly due to the pw the net heat transport relative to 0 1 c is northward but undergoes a rapid northward decrease suggesting an area averaged surface heat loss of 50 100 w m 2 in the strait

genesis of palygorskite and calcretes in pliocene eskisehir basin west central anatolia turkey abstract calcretes are common in the eskisehir province and occur as powder nodules tubes fracture infills and hard laminated crusts they are white in color and developed in the near surface setting of the pliocene reddish brown mudstones calcrete profiles consist mainly of isolated calcrete occurrences within mudstone palygorskite occurs generally as a beige colored layer in the mudstone and also as a minor component in the calcretes the calcrete nodules are roughly spherical to ellipsoidal in shape with diameters of 3 to 20 cm and are composed mainly of micrite locally recrystallized to microsparite and sparite detrital quartz and feldspar float in the micritic groundmass circumgranular cracks crumbly fractures and rhizoliths are also present xrd analyses indicate that calcrete samples are comprised mainly of calcite accompanied by small amounts of palygorskite quartz feldspar smectite chlorite and locally accessory illite and amphibole the sem tem images indicate that palygorskite fibers formed singly as bundles knitted and or matted aggregates either covering calcite crystals or smectite aggregates or as a meniscus cement between smectite flakes the latter are precipitated from meteoric water flushed through the open pore system of the sediments close to the surface based on the sem images palygorskite is presumed to have formed authigenically by direct precipitation in the vadose zone of a lacustrine environment following precipitation of calcite the 13c and 18o values of calcite indicate calcretization from meteoric soil water in an arid environment enrichment of ba sr ni and lree relative to mree hree and a negative eu anomaly reflect the fractionation of feldspar and amphibole in the parent mudstone the palygorskite associated with calcretes and mudstone was precipitated from alkaline water rich in si al fe and mg having mg rich character with a structural formula of si7 94al0 06o20mg2 96al0 99fe0 31 oh 2 oh2 4ca0 12k0 01 nh2o the required elements were derived from ophiolitic melange and volcanic units

estimating unconfined compressive strength and elastic modulus of a fault breccia mixture of weak blocks and strong matrix determination of the compressive strength and elastic modulus of rocks from direct methods requires a large number of regularly shaped specimens weak rocks are usually not suitable for preparing smooth specimens and at best the preparation of such specimens is tedious time consuming and expensive fault breccias have very poor engineering properties and fall within the category of weak rocks these rocks usually cause problems not only in construction works but also in slopes or in underground works for this reason knowing the physical and mechanical properties of fault breccia is very important in rock engineering however little published material on the geomechanical properties of fault breccias is available geomechanical characterization of complex geological mixtures of competent blocks and weak matrix geomaterials such as melanges sheared serpentinites fault rocks and coarse pyroclastics is relatively new the term block in matrix rocks for complex geo materials was firstly described by raymond 1 as blocks of one lithology enclosed in materials of another lithology medley 2 introduced the term bimrocks a contraction of the term block in matrix rocks and defined a bimrock as a mixture of rocks composed of geotechnically significant blocks within a bonded matrix of finer the expression geotechnically significant means that there is mechanical contrast between blocks and matrix such as the ratio tan block tan matrixx2 the range in block sizes is between 5 and 75 of the characteristic

determination of geomechanical properties and collapse potential of a caliche by in situ and laboratory tests working in complex grounds have always been difficult for engineering geologists because of the heterogenous nature of such geo materials which results in different behaviors under stresses the caliches outcropping in the adana basin and its close vicinity are selected as the study material because of their highly complex nature and also understanding their mechanical behaviour and collapse potential is too difficult although their aerial extent is large in the region for this reason investigation of the collapse potential and mechanical behaviour of the caliches by applying new approaches besides the conventional in situ and laboratory tests is the purpose of the study the study includes five main stages such as measurements of caliche profiles in situ tests plate loading sampling shooting photographs for photoanalyses and laboratory studies four different levels such as hard pan silty sandy layer gravelly blocky layer and clayey level are described for the caliches employed the hard pan level is a weak rock with an average uniaxial compressive strength of 11 89 mpa while the others have typical soil characteristics a series of plate loading tests are applied on the blocky gravelly level of the caliche to determine the modulus of elasticity the modulus of elasticity and the allowable bearing capacity are determined between 28 6 65 3 and 1 5 2 0 mpa respectively to determine the grain size distribution curve in addition to sieve analyses a photoanalysis technique is also applied and a combination procedure between the results from both sieve analyses and photoanalyses is introduced and the grain size curves for the blocky gravelly level of the caliche are obtained according to the results of collapse potential index tests performed on the samples collected from 20 locations of the study area the soft pan level of the caliche has slight to moderate degree of collapse indices in the final stage various simple and statistically meaningful empirical equations are proposed for the indirect determination of the collapse index by employing simple paramateres

thermohaline circulation in the arctic mediterranean seas the renewal of the deep north atlantic by the various overflows of the greenland scotland ridges is only one manifestation of the convective and mixing processes which occur in the various basins and shelf areas to the north the arctic ocean and the greenland iceland and norwegian seas collectively called the arctic mediterranean the traditional site of deep ventilation for these basins is the greenland sea but a growing body of evidence also points to the arctic ocean as a major source of deep water this deep water is relatively warm and saline and it appears to be a mixture of dense brine enriched shelf water with intermediate strata in the arctic ocean the deep water exits the arctic ocean along the greenland slope to mix with the greenland sea deep water conversely very cold low salinity deep water from the greenland sea enters the arctic ocean west of spitsbergen within the arctic ocean the lomonosov ridge excludes the greenland sea deep water from the canadian basin leaving the latter warm saline and rich in silica in general the entire deep water sphere of the arctic mediterranean is constrained by the greenland scotland ridges to circulate internally therefore it is certain of the intermediate waters formed in the greenland and iceland seas which ventilate the north atlantic these waters have a very short residence time in their formation areas and are therefore able to rapidly transmit surface induced signals into the deep north atlantic

improved chronostratigraphic reference curve of late neogene seawater 87sr 86sr we present a reference curve of seawater 87 sr 86 sr variation through the past 7 m y based on 455 samples of planktonic foraminifera from ocean drilling program odp site 758 in the indian ocean this single site curve is superior to extant curves because of several features 1 a continuous sedimentary section free of disturbances 2 a well determined and precise chronostratigraphy that is calibrated to numeric age on the basis of continuous magnetostratigraphy and a refined astronomical time scale 3 a high temporal resolution sample interval averages 15 ka 4 an improved analytical reproducibility and 5 a uniformly high sample quality the gross structure of the site 758 curve is generally similar to that observed in previous work but the increased temporal resolution and decreased analytical scatter of the curve provide improved chronostratigraphic resolution at the 95 confidence level uncertainties on age estimates range from 0 60 m y in the lower pleistocene and upper miocene to 2 03 m y in the middle pliocene moreover this detailed record identifies two periods of steplike increases in seawater 87 sr 86 sr 6 10 to 5 80 ma and 1 46 to 1 13 ma that are characterized by rates of change of 150 10 6 m y these features if verified at other sites indicate abrupt changes in the sr mass balance of the ocean and may be used as precise event markers in late neogene marine sections

the role of sea ice and other fresh water in the arctic circulation salinity stratification is critical to the vertical circulation of the high latitude ocean we here examine the control of the vertical circulation in the northern seas and the potential for altering it by considering the budgets and storage of fresh water in the arctic ocean and in the convective regions to the south we find that the present day greenland and iceland seas and probably also the labrador sea are rather delicately poised with respect to their ability to sustain convection small variations in the fresh water supplied to the convective gyres from the arctic ocean via the east greenland current can alter or stop the convection in what may be a modern analog to the halocline catastrophes proposed for the distant past the north atlantic salinity anomaly of the 1960s and 1970s is a recent example it must have had its origin in an increased fresh water discharge from the arctic ocean similarly the freshening and cooling of the deep north atlantic in recent years is a likely manifestation of the increased transfer of fresh water from the arctic ocean into the convective gyres finally we note that because of the temperature dependence of compressibility a slight salinity stratification in the convective gyres is required to efficiently ventilate the deep ocean

evaluating the geomechanical properties of misis fault breccia turkey abstract this study investigated the correlations between the uniaxial compressive strength ucs elastic modulus e or the differential stress and density p and s wave velocity volumetric block proportion vbp average block diameter d block average block diameter factor abdf aspect ratio and roundness the results were evaluated by both simple and multiple regression analysis simple regression analysis results show no correlation between ucs e or and the other examined parameters except s wave velocity a correlation was however found between ucs and s wave velocity for 25 and 75 vbp other significant models including density p and s wave velocity and textural properties for the prediction of ucs and were found by multiple regression analysis from these results it is concluded that the strength of the misis fault breccia cannot be defined by a single parameter such as vbp as is the case for some bimrocks it is also concluded that the models developed by multiple regression analysis can be used to predict the ucs and of the misis fault breccia the multiple regression models including two or three independent variables are the most practical equations using these equations to predict the ucs and of the fault breccia is easier faster and cheaper than conducting triaxial or uniaxial compressive strength tests

an ice water vortex at the edge of the east greenland current during the y mer 80 cruise in august 1980 we observed an ice feature of 60 km diameter having the shape of a breaking wave it lay at the edge of the east greenland drift ice in fram strait with its center at 79 15 n 00 38 e and the wave was breaking upstream relative to the east greenland current two conductivity temperature and depth sections across the feature in n s and e w directions revealed warm up to 4 3 c water some 60 km inside the polar front in lenses centered at 40 m depth but with an effect to beyond 600 m the temperature anomalies were accompanied by salinity anomalies so that there was little net effect on the density profile the form of the sections together with the ice distribution observed by vertical photography from a helicopter and surface motion observed by tracking four radar transponders all suggest that the feature is a vortex produced by an instability in the polar front it has similar characteristics to vortices investigated experimentally and theoretically by griffiths and linden 1981a b 1982 and observationally by wadhams et al 1979

current regimes across the east greenland polar front at 78 40 north latitude during summer 1984 four weeks of concurrent temperature and current observations from three moorings across the east greenland polar front at approximately 78 40 n showed pronounced differences between the current regimes on either side of the front east of the front vertical shear was minimal mean flow was not statistically significant and fluctuations showed evidence of wind influence west of the front vertical shear and southward mean flow were significant however observed fluctuations were not strongly influenced by local winds the mean current and density structure of the front was similar to that of a two layer boundary current model with constant potential vorticity current fluctuations west of the front were in part related to mesoscale features generated farther north and subsequently advected downstream by the east greenland current or to eddylike features apparently generated through potential vorticity conservation local instabilities of the front most likely account for the remainder of the mesoscale variability seen in the records

late quaternary palaeoecology palynology and palaeolimnology of a tropical lowland swamp rawa danau west java indonesia abstract sedimentological limnological and palynological analyses of a sediment core from a lowland site in west java indonesia provide a detailed palaeoenvironmental record for the late glacial and the holocene the record suggests open vegetation under inferred drier climatic conditions for the late glacial however there is no unequivocal evidence for cooler conditions at this time the onset of the holocene coincides with a change to more humid climatic conditions with the development of a fern rich closed forest vegetation type dramatic changes in diatom community composition provide a striking record of habitat change associated with lake shallowing but this process appears to be a result of basin in filling rather than variations in precipitation evaporation balance associated with climatic fluctuations evidence for human impact on the vegetation development is restricted to the last few hundred years

the contribution of geostatistics to the characterisation of some bimrock properties abstract this paper introduces a geostatistical approach for characterising the morphological and spatial variability of rock inclusions in bimrocks and for attempting their direct mechanical characterization through an indirect description deduced by image analysis of outcrop images the study was carried out on the shale limestone chaotic complex slcc bimrock which is affected by several slope stability problems in the disused santa barbara open pit mine tuscany italy due to its complex heterogeneity the mechanical characterization of slcc was based on a limited number of non conventional shear tests bimtests due to the relevant influence of rock inclusions on bimrock strength the study focused on identifying the possible image parameters characterising content and variability of rock inclusions in each sampled picture a two step analysis was carried out for a identification of an image parameter centimetric scale that is able to grasp some property of rock fragment shape and size spatial distribution b verification of the correlation at the outcrop scale multimetric scale between the bimrock strength parameters and the new regionalised variables rev describing image properties related to rock fragment distribution a geostatistical approach was adopted for both steps but applied to two different problems at two different scales with different variables an extensive sampling of outcrop pictures was carried out and a variogram analysis was performed on the rock fragment indicator variable i b x y defined at the image scale and obtained through the digital segmentation of the collected pictures a very good link was observed between the geostatistical model parameters and the content size and spatial variability of rock fragments shown in every picture the values of the total sill of the block indicator variograms were then assumed as a new rev c tot x y defined all over the sllc outcrop a cross covariance was computed between the variogram total sill and the friction angle x y and cohesion c x y at the scale of the whole outcrop area and a preliminary analysis showed a likely correlation

evolution and dynamics of the flow through herald canyon in the western chukchi sea abstract the flow of summer and winter pacific water masses through herald canyon is investigated using data from a high resolution hydrographic velocity survey conducted in summer 2004 the survey was part of the russian american long term census of the arctic rusalca program and consisted of four cross canyon transects occupied over a 2 day period at the time of the survey dense winter water was entering the western side of the canyon from the chukchi sea flowing alongside a poleward jet of summer water on the canyon s eastern flank as the dense water progressed northward it switched sides of the canyon and underwent a sudden increase in layer thickness this coincided with vertical mixing near the interface of the winter and summer water producing a new water mass mode exiting the canyon all of these features are consistent with the notion of hydraulic activity occurring in the canyon a three layer hydraulic theory is applied to the flow which suggests that it is supercritical and that hydraulic control is likely a lock exchange formulation accurately predicts the northward transport of the winter water the origin of the winter water and the manner in which it drains into the canyon is investigated using satellite ice concentration data atmospheric re analysis fields historical in situ data and a simple circulation model finally the fate of the pacific water exiting the canyon and its connection to the chukchi shelfbreak current is discussed

seasonal variations of sea ice motion in the transpolar drift stream drifting buoy data for 1979 85 and meteorological fields for 1960 85 are used to assess sea ice motion in the transpolar drift stream although the long term mean ice drift in this stream is toward the fram strait three years 1979 81 with adequate drifting buoy data coverage show reversed ice motion over 30 day periods in summer this phenomenon is a response to seasonally changing wind forcing

a 135 000 year record of vegetational and climatic change from the bandung area west java indonesia sedimentological and palynological analyses of sediment cores from the intramontane bandung basin west java indonesia provide a first palaeoclimatic record for the indonesian region covering continuously the last 135 000 years our data on palaeosol development indicate anomalously dry conditions for the final part of the penultimate glacial period around 135 000 yr b p and very warm and humid interglacial conditions from 126 000 to 81 000 yr b p during the transition to the last glacial period around 81 000 yr b p freshwater swamp forest of the bandung plain was replaced by an open swamp vegetation dominated by grasses and sedges indicating a change to considerably drier conditions possibly related to reduced moisture uptake by the nw monsoon as a consequence of lower sea levels at the onset of glacial conditions a strong reduction in asplenium ferns from 81 000 to 74 000 yr b p suggests that drier conditions may also have occurred in the mountains of the bandung area while increased numbers indicate that from 74 000 to 47 000 yr b p it was slightly wetter again inferred depression of montane vegetation zones and reduced fern percentages suggests distinctly cooler and possibly drier climatic conditions prevailed in the bandung area from 47 000 to approximately 20 000 yr b p for the last glacial maximum 4 7 c lower temperatures are recorded

canadian basin freshwater sources and changes results from the 2005 arctic ocean section 1 we present measurements of oxygen isotope ratios and nutrient concentrations along the 2005 arctic ocean section aboard the icebreaker oden the data are used to estimate freshwater contributions from meteoric water mainly river runoff sea ice meltwater and chukchi sea shelf water itself a combination of pacific and indigenous arctic water types nutrients ratios are combined to form quasi conservative water mass tracers phosphate star n star and the empirical arctic n p relationship and used along with salinity and 18o which are conservative in the ocean interior disagreements between two different freshwater analyses in the western arctic are largely resolved using a salinity dependent redfield ratio a new estimate of the pacific end member and an analysis of the bering strait inflow contribution to detraining shelf waters freshwater components from 2005 are placed into the context of the overlapping 1994 arctic ocean section aboard the louis st laurent and a time series of hydrographic tracer casts between 1987 and 1992 in the canada basin compared to 1987 1994 the 2005 transect exhibits increased meteoric water concentrations in the northern part of the canadian basin and a decrease in the southern part this pattern is related to changes in the distribution of wind stress curl during the several years prior to each sampling campaign in addition a previously observed correlation between sea ice formation and river runoff disappears over the central arctic in 2005 a change that we attribute to a northward shift of sea ice formation resampling approximately every 3 years should resolve the dynamics driving changes in freshwater and nutrient distributions

laboratory studies of thermally and or salinity driven flows with partial mixing 1 stommel transitions and multiple flow states 1 laboratory studies with flows driven by both temperature and salinity differences illustrate the role of partial mixing in such flows the results are compared to fundamental box model results in the classic stommel experiment an experimental chamber is heated from below and exposed to a steady flux of salt water from above the chamber is laterally connected to a reservoir of fresh isothermal water this duplicates in part the well known box models of deep ocean and estuarine circulation where both temperature and salinity determine the density in the chamber that drives a steady exchange flow between chamber and reservoir two locally stable modes of circulation are found within a well known range of the temperature and salinity forcing one mode is primarily temperature driven the t mode and one mode is primarily salinity driven the s mode with hysteresis and stommel transitions between the two modes new experiments with limited turbulent mixing and a narrow vertical slot in the sidewall between a laboratory test chamber and the reservoir produce a three layer structure for the s mode and a two layer structure for the t mode hysteresis and the stommel transitions are considerably smaller than in the fully mixed box models results are consistent with the notion that the arctic ocean is presently in the layered s mode

study on uniaxial compressive strength point load strength index dynamic and physical properties of serpentinites from central greece test results and empirical relations although many studies have been carried out to determine physical dynamic and mechanical properties and to establish relationships among them for several rocks only few have been focused on serpentinites determination of the mechanical properties such as uniaxial compressive strength the most fundamental property in any geotechnical work is usually difficult for these types of rocks because preparation of the standard size cores from serpentinites is quite difficult this paper presents the physical dynamic and mechanical properties investigates the relationships among them and attempts to derive reliable empirical approaches for the determination of uniaxial compressive strength formed from the above mentioned properties for serpentinites for this purpose a variety of serpentinite samples taken from the othrys and kallidromo mts central greece were tested in accordance with astm and isrm standards the same samples were subjected to petrographic studies the results were statistically described and analyzed using the method of least squares regression

on evaluating the stability of the baiyian ancient landslide in the three gorges reservoir area yangtze river a geological history analysis numerous landslides have occurred during the construction of the three gorges reservoir of the yangtze river although the underlying causal factor of these landslides was heavy rainfall the construction process was the trigger of some of them we report here a systematic study aimed at reconstructing the geological history of an ancient landslide and based on our results an evaluation of the role of the history on current landslide stability data from detailed field surveys and the studies on geological dating revealed that the baiyian landslide was composed of five structural parts of different geological ages such as a sliding belt disturbed rocks ancient colluvium alluvium of the yangtze river and slope wash the succession of ancient climates terraces and tectonic processes in the study area were examined from 300 ka ago the evolutionary history of the baiyian ancient landslide can be divided into five distinct stages development occurrence deposition collapse and disintegration some parts of the ancient landslide are currently prone to instability due to the combination effects of heavy rainfall and construction of the reservoir

seismic sequence stratigraphic analysis of the carbonate platform north offshore taiping island dangerous grounds south china sea abstract taiping island also known as itu aba is the largest natural terrestrial landmass in the south china sea and is centrally located using bathymetry and marine multi channel seismic data we explored the seismic stratigraphic features of the offshore and isolated carbonate platform north of taiping island the western flank of the carbonate platform is characterized by an intercalation between high amplitude and low amplitude reflections showing the landward and seaward migration of the platform foreslope deposits in addition there are two offshore carbonate build ups that are underlain by normal faults six sequence boundaries and five depositional sequences caused by eustatic sea level cycles are identified and correlated with the eustatic sea level change chart although the evolution of the seismic sequences is partly controlled by local tectonics the overall stacking pattern of the sedimentary strata in our study area reveals five third order cycles and one second order cycle which is in accordance with the eustatic sea level chart additionally the formations of the western taiping seamount group and the zhenghe daoming trough are preliminarily analyzed based on seismic data

prediction of the wetting induced collapse behaviour using the soil water characteristic curve abstract collapsible soils go through three distinct phases in response to matric suction decrease during wetting pre collapse phase collapse phase and post collapse phase it is reasonable and conservative to consider a strain path that includes a pre collapse phase in which constant volume is maintained and a collapse phase that extends to the final matric suction to be experienced by collapsible soils during wetting upon this assumption a method is proposed for predicting the collapse behaviour due to wetting to use the proposed method two parameters critical suction and collapse rate are required the former is the suction value below which significant collapse deformations take place in response to matric suction decease and the later is the rate at which void ratio reduces with matric suction in the collapse phase the value of critical suction can be estimated from the water entry value taking account of both the microstructure characteristics and collapse mechanism of fine grained collapsible soils the wetting soil water characteristic curve thus can be used as a tool five sets of data of wetting tests on both compacted and natural collapsible soils reported in the literature were used to validate the proposed method the critical suction values were estimated from the water entry value with parameter a that is suggested to vary between 0 10 and 0 25 for compacted soils and to be lower for natural collapsible soils the results of a field permeation test in collapsible loess soils were also used to validate the proposed method the relatively good agreement between the measured and estimated collapse deformations suggests that the proposed method can provide reasonable prediction of the collapse behaviour due to wetting

an investigation of the dynamics of the east greenland current in fram strait based on a simple analytical model abstract the east greenland current egc in fram strait is examined in summer based on the hydrographic data from the mizex 84 experiment and its dynamics is further analyzed using a simple analytical model from the observed density field the southward geostrophic transport relative to the bottom in the egc is estimated to be about 4 sv sv 106 m3 s 1 at 78 4 n which assuming a ratio 1 1 between the bottom and the relative transports as suggested in the literature allows one to postulate a 4 sv bottom transport the hydrographic data also reveal a northward gradient of potential energy along the east greenland slope between 77 5 n and 80 5 n such a gradient is the prerequisite for the existence of the joint effect of baroclinicity and relief jebar which is here proposed as a driving mechanism for the bottom transport in the egc a model with idealized topography and a density distribution prescribed from the above data is constructed based on a steady state vorticity equation in which the

an approach to predicting the overall strengths of unwelded bimrocks and bimsoils the strength of geological materials is a fundamental property used in the design of civil engineering works including projects constructed in complex geological mixtures or fragmented rocks such as melanges fault rocks coarse pyroclastic rocks breccias and sheared serpentines these and other often chaotic mechanically and or spatially heterogeneous rock masses are composed of relatively strong rock blocks surrounded by weaker matrix rocks these common rock mixtures known as bimrocks block in matrix rocks or bimsoils when the matrix material is soil like are very difficult to evaluate it is almost impossible to recover high quality undisturbed drill core samples or to prepare laboratory specimens perform laboratory studies and evaluate geomechanical parameters such as cohesion internal friction angle and uniaxial compressive strength from these complex mixtures there is sparse literature describing empirical and laboratory studies on strength of bimrocks hence this study was devised to develop a preliminary bim strength criterion a generalized conceptual empirical approach for predicting the overall strength of unwelded bimrocks and bimsoils the approach considered fundamental rules of rock and soil mechanics and the reported mechanical behavior of bimrocks as a function of volumetric block proportion vbp as reported in literature in addition cores of artificial bimrock were prepared in the laboratory for uniaxial and triaxial compression testing empirical equations useful for predicting the strength of bimrocks were devised which depend on practical charts and input parameters such as parameter a defined to relate the contact strength between matrix and blocks the predictive equations were calibrated by using the literature database the predictive performance of the preliminary bim strength criterion for bimrocks and bimsoils was checked by using the established database and was found to have high predictability although erring slightly on the conservative side

estimating the deformation modulus of rock masses a comparative study although the modulus of deformation of rock masses has crucial importance for geotechnical projects such as tunnels and dams the determination of this parameter by in situ tests requires considerable costs and involves difficult operational processes for this reason empirical equations for the indirect estimation of the modulus of deformation are an interesting issue for rock engineers and engineering geologists this study includes assessment of the prediction performances of some existing empirical equations using in situ plate loading test data and rock mass properties producing an empirical equation depending on the new data construction of a fuzzy inference system for the estimation of modulus of deformation and making a comparison between results obtained from the empirical equations and fuzzy inference system a series of calculations and statistical analyses were undertaken it is concluded that the performance of the empirical equations and fuzzy inference system obtained in this study is satisfactory however the prediction models developed in this study are limited by the number of the data used and the rock types employed for these reasons a cross check should be performed before using these prediction models for design purposes

dry climate near the western pacific warm pool pleistocene caliches of the nansha islands south china sea abstract the nansha spratly islands are located in the middle of the south china sea at about 10 n near the northwestern margin of the western pacific warm pool wpwp a borehole was drilled at an atoll at nansha and cores were taken the upper 165 4 m of the borehole consists entirely of limestone of reef facies and lagoon facies which had been influenced by extensive meteoric diagenesis petrographic and geochemical studies have identified at least four subaerial exposure surfaces ses in the pleistocene carbonate sequence these ses are thought to have resulted from global sea level changes and characterized by caliche formation when developed in limestone caliches typically form in areas where annual precipitation ranges from 500 mm up to about 1200 mm compared with 1800 2200 mm of annual rainfall of the present day nansha islands the nansha caliche therefore indicates the existence of several dry climate episodes during pleistocene sea level lowstands lower rainfall and higher evaporation during such dry conditions may explain the higher sea surface salinities reported elsewhere in the south china sea the nansha caliche may also indicate reduced extent of the wpwp and southerly shift of the intertropical convergence zone during major sea level lowstands

freshwater distribution in the arctic ocean simulation with a high resolution model and model data comparison 1 a high resolution numerical simulation of the arctic ocean is analyzed in order to study the fate of river runoff and freshwater fluxes in the arctic ocean the model is driven by realistic winds and thermodynamic forcing from the european centre for medium range weather forecasting ecmwf reanalysis data set dye tracers have been added to visualize the pathways followed by low salinity water from the major arctic rivers and bering strait inflow the model is spun up using repeated forcing with the 1979 annual cycle for 20 years then the 1979 through 1998 atmospheric forcing is applied under the influence of the 1979 through early 1980s winds a large plume of river runoff exits the broad eurasian shelf seas along the lomonosov ridge starting in about 1985 the locus of shelf to basin transport shifts eastward to the alpha mendeleyev ridge complex this shift in the model output is related to changes in the sea surface height ssh fields which we attribute primarily to shifts in surface wind stresses model resolution runoff inputs and relaxation terms in the lena river delta region are analyzed in detail to expose issues with model performance at boundaries with freshwater inflow suggestions are made for improving future simulations of river runoff in basin scale models

estimating the uniaxial compressive strength of a volcanic bimrock abstract preparation of the standard sized cores from geological mixtures or fragmented rocks such as melanges fault rocks coarse pyroclastic rocks breccias and sheared serpentinites is often extremely difficult therefore determination of the mechanical parameters such as cohesion friction angle and ucs is extraordinarily difficult for these types of rocks this paper presents the results of studies using ankara agglomerate to develop an empirical approach for the determination of the ucs for a volcaniclastic mixture of strong andesite blocks within weak tuff matrix formed from the aggregation of volcanically exploded rock debris mixed with ash fall tuff i e a bock in matrix rock or bimrock the uniaxial compressive strength of a volcanic bimrock can be predicted using the conceptual approach within as yet poorly understood error limits therefore the approach introduced is open to improvement depending on the number of data and cases including different type of bimrocks

the impact of open oceanic processes on the antarctic bottom water outflows abstractthe impact of open oceanic processes on the antarctic bottom water aabw outflows is investigated using a numerical model with a focus on outflows that occur through deep channels a major branch of the aabw outflow is known to occur as an overflow from the filchner depression to the weddell sea through a deep channel a few hundred kilometers wide and a sill roughly 500 m deep when this overflow enters the weddell sea it encounters the antarctic slope front asf at the shelf break a density front commonly found along the antarctic continental shelf break the presence of an aabw outflow and the asf create a v shaped isopycnal structure across the shelf break indicating an interaction between the overflow and oceanic processes model experiments show the overflow transport to increase significantly when an oceanic wind stress increases the depth of the asf this enhancement of overflow transport occurs because the channel walls allow a pressure gradient in the along slope direction to exist a

tectono stratigraphic terranes and detachment faulting of the south china sea and sulu sea abstract geoscientific data acquired from the south china sea and sulu sea areas by bgr since 1977 are compiled and interpreted as comprehensive data sets together with available information of commercial wells and drillsites of the ocean drilling program odp generalized stratigraphy and lithology are discussed and correlated with the interpreted seismic profiles on the basis of the stratigraphic and structural analysis 5 main tectono stratigraphic terranes are defined for the south china sea and 4 main terranes for the sulu sea respectively the dangerous grounds reed bank palawan nw borneo trough and palawan island represent terranes of continental origin which developed on the proto china margin by uniform sense low angle simple shearing within the crust in late cretaceous to early paleocene this rift was abandoned and a new westward propagating rift system developed north of the dangerous grounds reed bank area from the middle eocene to the oligocene early miocene together with seafloor spreading in the south china sea basin the leading edge of the southward drifting continental terranes collided with the late cretaceous to early eocene subduction complex of the northernmost terrane of the proto sulu sea continuous convergence of these terranes back arc spreading creating the se sulu sea terrane and the assumed anti clockwise rotation of borneo are responsible for the complex collision compression structures of the sulu sea terranes including the formation of splinters of oceanic crust major right lateral wrench systems are nnw sse running up to 500 km long and cut across most of the identified terranes wrenching presumably ceased 12 to 16 myr ago

progressive development of block in matrix fabric in a shale dominated shear zone insights from the bobbio tectonic window northern apennines italy 1 block in matrix is a common fabric characterizing highly deformed to apparently chaotic rocks originated by sedimentary tectonic and mud diapiric processes in many exposed orogenic belts a true melange originates when this fabric is associated with mixing of rocks of different ages and provenance as that characterizing the main decollement shear zone developed between the highly allochthonous ligurian nappe and its substratum of foredeep deposits at the margins of the bobbio tectonic window trebbia valley northern apennines mixing of rocks by both mass transport processes and synsedimentary thrusting occurs at the front and tectonic erosion at the base of the nappe during its emplacement evidence of polyphased deformations spanning from liquefaction related and hydroplastic structures to pseudo hydrofracturing features and mineralized veining have been recognized within the marginal portions and along the sheared contacts of blocks encased within a scaly matrix crosscutting relationships testify a progressive deformation involving a transition from mesoscopic ductile to brittle conditions with the significant contribution of fluid overpressure a novel evolutionary scheme for block in matrix fabric development is here proposed involving the progressive dismembering of already highly deformed units originally developed in non to poorly lithified conditions through a generalized simple shearing achieved during the evolution of the shear zone coupled with strain hardening due to tectonic compaction synkinematic diagenesis and fluid expulsion

a simple model of the arctic ocean response to annular atmospheric modes 1 a dynamical mechanism is described that modulates the tilt of the sea surface height and pycnocline depth between the central arctic and the continental shelves a simple analytical model is presented forced with idealized zonal winds over an idealized 2 layer cylinder representing the arctic ocean ekman transports are linked to sea surface and pycnocline tilt anomalies and basin scale circulation in response to an annular wind anomaly we compare the results to tide gauge data as well as results from a more realistic numerical simulation and find that the model explains a major fraction of the interannual to decade scale sea surface height anomalies at arctic coastal tide gauges the analytical model indicates for example that on the order of 10 cm of the observed rise of about 18 cm in coastal arctic sea surface height between about 1985 and 1993 was probably a response to increased westerly winds associated with a strong positive phase of the northern annular mode of atmospheric variability the pycnocline depth anomaly time series from the model is used to calculate implied changes in the outflow of relatively fresh polar water to the north atlantic the comparisons indicate that the ekman transport mechanism is important to changes in the export of buoyancy from the arctic ocean on seasonal interannual and decadal timescales

beaufort gyre freshwater reservoir state and variability from observations 1 we investigate basin scale mechanisms regulating anomalies in freshwater content fwc in the beaufort gyre bg of the arctic ocean using historical observations and data collected in 2003 2007 specifically the mean annual cycle and interannual and decadal fwc variability are explored the major cause of the large fwc in the bg is the process of ekman pumping ep due to the arctic high anticyclonic circulation centered in the bg the mean seasonal cycle of liquid fwc is a result of interplay between the mechanical ep and thermal ice transformations factors and has two peaks one peak occurs around june july when the sea ice thickness reaches its minimum maximum ice melt the second maximum is observed in november january when wind curl is strongest maximum ep and the salt input from the growing ice has not yet reached its maximum interannual changes in fwc during 2003 2007 are characterized by a strong positive trend in the region varying by location with a maximum of approximately 170 cm a 1 in the center of ep influenced region decadal fwc variability in the period 1950 2000 is dominated by a significant change in the 1990s forced by an atmospheric circulation regime change the center of maximum fwc shifted to the southeast and appeared to contract in area relative to the pre 1990s climatology in spite of the areal reduction the spatially integrated fwc increased by over 1000 km 3 relative to climatology