effect of joint orientation on the hydromechanical behavior of singly jointed sandstone experiencing undrained loading the hydromechanical behavior of singly jointed sandstone under undrained triaxial conditions was studied maximum induced pore water pressure was observed to increase with increasing joint orientation from 0 to 45 for all confining pressures considered for a 60 joint orientation a considerable drop in maximum induced pore water pressure was observed relative to the neighboring 45 and 75 joint orientations under 4 and 10 mpa of confinement at 25 mpa of confinement the drop in maximum induced pore water pressure for the 60 joint orientation was not so pronounced these observations were explained in terms of failure mechanism sliding versus shearing for the different joint orientations for sliding failure pore water pressure at failure did not decrease significantly from the maximum value whereas a marked pore water pressure decrease after maximum was observed in the process of sample loading when failure involved intact material rupture peak differential stress values at different joint orientations showed that the critical joint orientation was 60 and increasing confining pressure can reduce the influence of joints on the compressive strength of rock volumetric strain data showed that dilation related volume increase at or close to failure is significant for joint orientations of 0 30 45 and 90 but not for orientations of 60 and 75 at confining pressures of 4 and 10 mpa at 25 mpa of confinement none of the samples showed a considerable dilation related volume increase the results illustrate the major influence of failure mechanisms as governed by joint orientation confining pressure etc on the hydromechanical response of jointed rock

salt weathering simulation using a single immersion technique samples of concrete were subjected in an environmental cabinet to six different diurnal cycles of temperature and humidity change representative of desert surface conditions in the presence of a range of saturated salt solutions the samples were not subjected to repeated immersion or continuous partial immersion as has been the case in most previous experiments breakdown did occur nonetheless the two most effective cycles were one from egypt with a very high daytime maximum and one from the negev with high nocturnal humidity conditions cycles with relatively modest temperature and humidity cycles were ineffective in causing debris liberation

a boundary layer model for mars comparison with viking lander and entry data abstract a one dimensional boundary layer model for mars is described and its results are compared with viking data the model equations are similar to earth boundary layer models in that they include contributions from coriolis pressure gradient and frictional forces for momentum and radiation sensible heat flux convergence and advection for heat turbulent fluxes are computed from the level 2 second order closure theory of mellor and yamada with similarity relations employed for boundary conditions the pressure gradient force can be specified or computed from a simple slope model radiative heating is due to the absorption of solar and infrared radiation by co2 gas and suspended dust particles ground temperatures are computed by solving a surface heat budget using an accurate treatment of conduction into the martian soil the data used for comparison were obtained by the viking 1 and 2 landers for early northern summer at each site these data include a single profile of wind and temperature be

dust devil speeds directions of motion and general characteristics observed by the mars express high resolution stereo camera abstract a total of 205 dust devils were detected in 23 high resolution stereo camera hrsc images taken between january 2004 and july 2006 with the esa mars express orbiter in which average dust devil heights were 660 m and average diameters were 230 m for the first time dust devil velocities were directly measured from orbit and range from 1 to 59 m s the observed dust devil directions of motion are consistent with data derived from a general circulation model gcm in some respects hrsc dust devil properties agree favorably with data from the nasa mars exploration rover spirit dust devil analyses the spatial distribution of the active dust devils detected by hrsc supports the conjecture that the ascending branch of the hadley circulation is responsible for the increase in dust devil activity especially observed during southern summer between 50 and 60 s latitude combining the dust lifting rate of 19 kg km2 sol derived from the spirit observations with the fewer in number but larger in size dust devils from various other locations observed by hrsc we suggest that dust devils make a significant contribution to the dust entrainment into the atmosphere and to the martian dust cycle

petrography and reservoir physics ii relating thin section porosity to capillary pressure the association between pore types and throat size porosity in reservoir rocks is configured into a few types of pores whose size and shape are controlled by depositional fabric and postdepositional processes the size shape and abundance of each pore type can be objectively determined from thin section using image analysis and pattern recognition procedures each pore type tends to be associated with a limited range of throat sizes the association between pore type and throat size can be determined using regression procedures linking pore type data obtained from thin section with capillary pressure data to do so a set of samples is required wherein the association between pore type and throat size is fixed but where pore type proportions vary between samples this condition is met by a sample suite representing res rvoir facies from a single core or in many cases from a single field the relationship between pore type and throat size is an effective means to relate reservoirs in terms of the efficiency of the porous microstructure to multiphase flow parameters derived from the relationship can be used to construct accurate physical models that subdivide physical response in terms of the contributions of each pore type

laboratory simulation of the wick effect in salt weathering of rock the wick effect is the upward migration of saline solutions into rocks and their subsequent crystallization lower carboniferous sandstone blocks of rectangular shape have been subjected to this process in the laboratory using a range of salt types a range of salt concentrations and various mixtures of salts some treatments produced severe disintegration notably sodium carbonate and a mixture of sodium carbonate with magnesium sulphate whereas other salts including sodium chloride and gypsum were much less effective the debris produced by this experimental salt weathering included appreciable quantities of silt sized material which were analysed with a laser granulometer such material could provide a source for desert loess

recent near surface wind directions inferred from mapping sand ripples on martian dunes abstract the high resolution imaging science experiment hirise provides the capability to obtain orbital images of mars that are of sufficient resolution to record wind ripple patterns on the surfaces of sand dunes ripple patterns provide valuable insights into aeolian erosion and deposition on earth and mars in this study we develop a systematic mapping procedure to examine sand ripple orientations and create surface process maps to evaluate the recent wind flow over the dunes as well as the interplay of wind and dune shape by carefully examining the morphology of the dunes and the location of grainflow and grainfall on dune slipfaces the recent near surface wind direction short term wind can be identified results from the analysis of three dune fields on the floors of craters west of hellas basin show regional n nw se and ese wind directions in the three adjacent dune fields surface process and flow maps suggest a complex wind pattern the comparison of short term wind with dune constructing wind long term wind shows ne and ese winds may be persistent at least for the past thousands of years the results also show that the orientation of inferred wind direction on linear dunes is correlated with the crestlines which suggest that form flow interaction may take place the results of local wind flow documentation should improve martian surface wind modeling and advance our understanding of sand transport as well as the rates of sand mobility on both mars and earth

a new methodological approach to assess the stability of discontinuous rocky cliffs using in situ surveys supported by uav based techniques and 3 d finite element model a case study abstract this paper aims to present a new methodological approach for the stability assessment of coastal cliffs constituted of discontinuous rock masses the method entails in situ specific geostructural and geomechanical surveys three dimensional uav based photogrammetric structural models laboratory geotechnical tests and two and three dimensional finite element analysis fem the application of the method to a case study is then presented and discussed it regards a 600 m long sea rocky cliff located at sant andrea melendugno south of apulia se italy and faced to the southern adriatic sea here the cliff is made up of an about 15 m thick sequence of laminate calcisiltites alternate with bioturbated calcarenites belonging to the uggiano la chiesa fm middle upper pliocene the structural discontinuities detected with photogrammetry techniques were compared and validated with those derived from conventional in situ survey methods later on the paper discusses assumptions and results of two and three dimensional finite element models developed to investigate the potential failure mechanisms of the sea cliff accounting for pre existing weak planes or discontinuities with unfavourable orientation the failure mechanisms obtained by both fem analysis agree well with those typically observed in the study area

observations of an aeolian landscape from surface to orbit in gale crater abstract landscapes derived solely from aeolian processes are rare on earth because of the dominance of subaqueous processes in contrast aeolian derived landscapes should typify mars because of the absence of liquid water the long exposure times of surfaces and the presence of wind as the default geomorphic agent using the full range of available orbital and mars science laboratory rover curiosity images wind formed features in gale crater were cataloged and analyzed in order to characterize the aeolian landscape and to derive the evolution of the crater wind regime over time inferred wind directions show a dominance of regional northerly winds over geologic time scales but a dominance of topography driven katabatic winds in modern times landscapes in gale crater show a preponderance of aeolian features at all spatial scales interpreted processes forming these features include first cycle aeolian abrasion of bedrock pervasive deflation organization of available sand into bedforms abundant cratering and gravity driven wasting all of which occur over a background of slow physical weathering the observed landscapes are proposed to represent a spectrum of progressive surface denudation from fractured bedrock to retreating bedrock capped mesas to remnant hills capped by bedrock rubble to desert pavement plains this model of landscape evolution provides the mechanism by which northerly winds acting over 3 ga excavated tens of thousands of cubic kilometers of material from the once sediment filled crater thus carving the intra crater moat and exhuming mount sharp aeolis mons the current crater surface is relatively sand starved indicating that potential sediment deflation from the crater is greater than sediment production and that most exhumation of mount sharp occurred in the ancient geologic past

orthogonal microscopy image acquisition analysis technique for rock sections in polarizer angle domain abstract the microscopic identification of rock sections is one of the most basic research methods of petromineralogy which is important to the research of mineral composition pore throat characteristics interstitial filling etc the traditional manual identification method was time consuming and also burdened with errors due to the subjective nature of human judgment which can bring some uncertainties to the further results therefore this paper proposes a technique for image acquisition and analysis of rock sections based on sequential images of rock sections in angle domain under polarizing microscope the analysis includes the following three steps firstly based on the multi angles extinction feature of rock section the direction adaptive correlation coefficient method was used to characterize the edge of the rock sections and segment the rock grains a series of parameters including grain size roundness convexity flatness and roughness were also extracted to characterize the morphological features of rock grains quantitatively secondly the variation characteristics of multi channel parameters rgb and gray channel with angle domain were analyzed for different minerals and then the mineral composition was accurately identified on the basis of grain segmentation the pore structures including intergranular pores dissolved pores and throat were extracted and the parameters of pore structure were also obtained finally the distribution of the interstitials was characterized based on the change of the extinction characteristics of the interstitials in the pores image analysis technique based on rock sections with polarizing microscope provides an effective and convenient method for grain segmentation mineral composition classification pore identification and interstitial analysis

bimodal porosity in oolitic reservoir effect on productivity and log response rodessa limestone lower cretaceous east texas basin running duke field houston county texas is on a small domal structure in the east texas basin the field currently consists of five gas wells producing from the lower cretaceous rodessa limestone seven additional gas completions have been plugged the rodessa yields water free gas production from zones with water saturations in excess of 60 porosity ranges from 7 to 14 the depositional model depicted for the rodessa in this field starts with the development of an active organic buildup this was successively overlain by ooid skeletal peloid lime sands lagoonal lime muds and subsequently by anhydrite and shale six lithofacies based on core study were recognized for the rodessa each facies has a uniform diagenetic history in the field making porosity development predictable for each facies the one grainstone facies forms the reservoir in the field and has two distinct diagenetic sequences one consists of a marine isopachous cement followed by a later partial infilling of pore space by sparry calcite the resulting intergranular porosity has a unimodal pore size distribution in the other sequence a discontinuous meteoric phreatic cement is followed by sporadic patches of sparry cement the resulting pore size distribution is bimodal with intergranular macropores and intercrystalline micropores within peloids and micritized ooids water free gas production is limited to the rock with the bimodal pore system macropores hold movable gas and micropores hold bound water within grains where core data are not available cross plotting techniques using geophysical logs are suggested as methods for separating the productive from the nonproductive grainstone

a two stage model of fracture of rocks in this paper we propose a two stage model of rock fracture in the first stage cracks or local regions of failure are uncorrelated and occur randomly throughout the rock in response to loading of pre existing flaws as damage accumulates in the rock there is a gradual increase in the probability that large clusters of closely spaced cracks or local failure sites will develop based on statistical arguments a critical density of damage will occur where clusters of flaws become large enough to lead to larger scale failure of the rock stage two while crack interaction and cooperative failure is expected to occur within clusters of closely spaced cracks the initial development of clusters is predicted based on the random variation in pre existing flaw populations thus the onset of the unstable second stage in the model can be computed from the generation of random uncorrelated damage the proposed model incorporates notions of the kinetic and therefore time dependent nature of the strength of solids as well as the discrete hierarchic structure of rocks and the flaw populations that lead to damage accumulation the advantage offered by this model is that its salient features are valid for fracture processes occurring over a wide range of scales including earthquake processes a notion of the rank of fracture fracture size is introduced and criteria are presented for both fracture nucleation and the transition of the failure process from one scale to another

physico mechanical properties and durability performance of natural building and decorative carbonate stones from cyprus natural stone was the primary building material in cyprus in the past nowadays its use is mostly confined to decorative purposes and restoration projects this study represents the first thorough and systematic investigation of the characteristics of local carbonate stone the variety of the results recorded highlights the complexity of this natural geomaterial and hence the particular attention needed before selecting the appropriate lithotype in construction practice stones coming from the same geological formation exhibit significant variations in their physico mechanical properties the materials durability against salt crystallization is explained with reference to their pore structure and flexural strength revealing that in many cases small differences may have a significant impact on stone performance the study also investigates the use of novel microdestructive techniques in the prediction of the mechanical properties of the stones under study these techniques can be especially useful in the characterization of monumental stone where sampling is limited or when in situ characterization of stone is required natural stone has been extensively used throughout the history of mankind both for building and decorative purposes even though it is considered one of the most durable traditional geomaterials existing stone structures and monuments often show evidence of weathering and decay stress inflicted during use and by local climate are the major contributing factors to the degradation of building stone the precise response of individual stone samples is highly variable this is attributed to the complex nature and physico mechanical behaviour of natural stone understanding the materials performance under loading or different environmental conditions is therefore considered of crucial importance in ensuring the sustainable use of stone in construction practice

mars atmospheric winds indicated by motion of the viking landers during parachute descent winds in the martian atmosphere at altitudes from 1 5 to 3 5 km have been determined from parachute descent trajectories of the two viking landers viking 2 reached equilibrium with nearly steady winds of 8 m s to the southeast below 3 3 km at 1000 lt viking 1 winds at 1615 lt rotated clockwise with decreasing altitude but were generally to the northwest at 20 m s at 1 5 km the viking 1 wind direction was close to that measured by the landed anemometer at the same local time while at the viking 2 site wind direction at 1 5 km was nearly opposite that near the surface this is consistent with the fact that viking 1 descended within a vigorously convective boundary layer while viking 2 at 1 5 km was above the boundary layer turbulent velocities in the viking 1 boundary layer were 3 m s mean upflow velocity was 1 m s the viking 2 atmosphere was relatively quiescent with orderly wind directional variation possibly suggesting the presence of waves comparison of the measured winds with a recent global circulation model showed little or no correspondence probably an indication that the winds were locally controlled the boundary layer slope wind model of haberle et al 1993 with ground slope adjusted to give best fit to these and landed meteorology data gave roughly the wind direction and the observed magnitude within a factor of 2 but with opposite rotation of the wind vector with altitude the ground slopes deduced are consistent with terrain observed in approach to the viking 1 landing and do not conflict with the less definitive terrain data at the viking 2 site the high sensitivity of winds at altitudes up to several kilometers to terrain slopes as small as a few meters per kilometer would suggest that slope winds may be widely found in the lowest few kilometers of mars atmosphere

carbon export and cycling by the yukon tanana and porcupine rivers alaska 2001 2005 1 loads and yields of dissolved and particulate organic and inorganic carbon doc poc dic pic were measured and modeled at three locations on the yukon river yr and on the tanana and porcupine rivers tr pr in alaska during 2001 2005 total yr carbon export averaged 7 8 tg c yr 1 30 as oc and 70 as ic total c yields 0 39 1 03 mol c m 2 yr 1 were proportional to water yields 139 356 mm yr 1 r2 0 84 at all locations summer doc had an aged component fraction modern fm 0 94 0 97 except in the permafrost wetland dominated pr where doc was modern poc had fm 0 63 0 70 doc had high concentration high aromaticity and high hydrophobic content in spring and low concentration low aromaticity and high hydrophilic content in winter about half of annual doc export occurred during spring dic concentration and isotopic composition were strongly affected by dissolution of suspended carbonates in glacial meltwater during summer

salt weathering influence of evaporation rate supersaturation and crystallization pattern micro and macroscale experiments which document the dynamics of salt damage to porous stone have yielded data which expose weaknesses in earlier interpretations previously unexplained differences are found in crystal morphology crystallization patterns kinetics and substrate damage when comparing the growth of mirabilite na2so4 10h2o and thenardite na2so4 versus halite nacl the crystallization pattern of sodium sulphate was strongly affected by relative humidity rh while a lesser rh effect was observed for sodium chloride macroscale experiments confirmed that mirabilite crystallizing at rh 50 per cent and thenardite crystallizing at rh 50 per cent tend to form subflorescence in highly localized areas under conditions of constant rh and temperature this crystallization pattern was more damaging than that of halite since halite tended to grow as efflorescence or by filling the smallest pores of the stone in a homogeneous fashion a result which contradicts wellman and wilson s theoretical model of salt damage low rh promoted rapid evaporation of saline solutions and higher supersaturation levels resulting in the greatest damage to the stone in the case of both sodium sulphate and sodium chloride crystallization at any particular crystallization condition sodium chloride tended to reach lower supersaturation levels resulting in the crystallization of isometric crystals and created negligible damage while sodium sulphate reached higher supersaturation ratios resulting in non equilibrium crystal shapes resulting in significant damage esem showed no damage from sodium sulphate due to hydration instead after water condensation on thenardite crystals rapid dissolution followed by precipitation of mirabilite took place resulting in stone damage by means of crystallization pressure generation it is concluded that salt damage due to crystallization pressure appears to be largely a function of solution supersaturation ratio and location of crystallization these key factors are related to solution properties and evaporation rates which are constrained by solution composition environmental conditions substrate properties and salt crystallization growth patterns when combined with a critical review of salt damage literature these experiments allow the development of a model which explains variations in damage related to combinations of different salts substrates and environmental conditions

the effects of aqueous chemical environments on crack and hydraulic fracture propagation and morphologies the role of surface active aqueous environments in chemomechanical weakening of geologic materials is examined in light of the results of hydraulic fracture tests in sandstone calorimetric studies and crack propagation tests in synthetic quartz in hydraulic fracture tests mploying crab orchard sandstone it was found that the effective hydraulic fracture pressure was reduced over that attained with distilled water when 5 10 4 m aqueous solutions of dodecyl trimethyl ammonium bromide dtab were used as the hydraulic fracture medium the degree of branching of the fractures was also increased in the presence of the dtab solution previously reported crack propagation stress values in quartz exposed to distilled water and various dtab solutions displayed the same trend when examined in this study the cracks propagated in the presence of dtab solutions also displayed a greater degree of branching than those propagated in the presence of distilled water or the ambient atmosphere these results and results from calorimetric measurements of the heats of adsorption and desorption from quartz of distilled water and dtab are synthesized in a model relating the weakening and morphological effects to a reduction in the surface free energy of quartz due to adsorption of species from the chemical environment onto the surfaces of the quartz and sandstone

a sediment and organic carbon budget for the canadian beaufort shelf abstract the arctic ocean accounts for 20 of the world s continental shelves because the arctic is sensitive to global change budgets of organic carbon for its shelves are of immediate interest the mackenzie shelf of the canadian beaufort sea is the best north american proxy for the enormous eurasian shelves large area large river input and the only site for which a complete organic carbon budget can be attempted due to an extensive data base a mass balance for the mackenzie shelf has been constructed for sediments terrestrial organic carbon and primary produced carbon we have considered allochthonous inputs from the mackenzie river from coastal erosion from smaller rivers from groundwater from the atmosphere and import by ice the mackenzie river dominates the supply to the beaufort shelf of inorganic sediment 127 mt a 1 and paniculate and dissolved terrestrial carbon 2 1 mt a 1 poc 1 3 mt a 1 doc the combined input from all other sources contributes only about 5 of the mackenzie load using sediment accumulation data we estimate that about half of the sediment supply is trapped in the delta about 40 on the shelf and the remainder escapes the shelf edge by various processes autochthonous primary production in the delta and on the shelf adds a further 3 3 mt a 1 of particulate organic carbon a box model has been constructed to account for sediment terrestrial organic carbon and primary produced carbon whereas about 60 of the terrestrial poc is preserved in delta and shelf sediments it appears that most 97 of the primary produced carbon is recycled and not preserved in sediments confidence in the budget should be improved by focusing future research on the determination of modern sedimentation rates on the delta and shelf measurement of organic carbon content of deltaic sediments determination of primary production on the shelf and determination of the relative proportions of terrestrial and marine organic carbon preserved in sediments

salt as an agent in the development of cavernous weathering a well recognized spatial association exists between cavernous weathering and the presence of soluble salts disaggregation of rock in caverns is attributed to mechanical pressures exerted by crystallization and or hydration of salts however scanning electron micrographic analysis demonstrates that solutional etching is the major weathering process in caverns in near coastal locations in western australia and new south wales australia it is suggested here that the breakdown of the caverned sandstone is caused by sodium chloride which increases the rate of quartz dissolution

empirical prediction of porosity and permeability in sandstones current efforts to predict porosity and permeability in sandstones prior to drilling are focused on empirical and process oriented models empirical predictions are based on the correlation between porosity and permeability and a limited number of parameters obtained from calibration data sets or estimated from appropriate geologic models of these parameters the most important are detrital composition grain size sorting and temperature history or pressure history or both despite its limitations the empirical approach provides accurate predrill predictions of reservoir quality in many sandstones containing not only primary but also secondary porosity and permeability predictions of the average porosity and permeability of target sandstones are arbitrarily defined h re as accurate if they fall within 2 porosity of the mean measured porosity and within the same order of magnitude as the mean measured permeability in a sample population representing the interval of interest the effectiveness of the empirical predictive approach is illustrated by case studies from the taranaki basin new zealand and yacheng field people s republic of china these studies indicate that empirical predictions are basin specific or even play specific and require at least some understanding of fundamental processes affecting reservoir quality of a given sandstone target process oriented approaches attempting to model the effect of diagenesis on reservoir quality are hampered by inadequate quantitative understanding of the processes responsible for preserving primary porosity and generating secondary porosity and permeability until adequate quantification of the sandstone diagenesis processes is achieved empirical models have a distinct advantage over process oriented models in providing reliable predictions of reservoir quality in many sandstone intervals

the origin of honeycomb weathering honeycomb weathering occurs throughout the world but the origin remains a matter of controversy wind erosion exfoliation frost shattering and salt weathering have been proposed as explanations although few attempts have been made to substantiate these hypotheses with chemical or mineralogical studies chemical analyses and field observations indicate that honeycomb weathering in coastal exposures of arkosic sandstone near bellingham washington results from evaporation of salt water deposited by wave splash microscopic examination of weathered surfaces show that erosion results from disaggregation of mineral grains rather than from chemical decomposition thin walls separating adjacent cavities seem to be due to protective effects of organic coatings produced by microscopic algae inhabiting the rock surface cavity walls are not reinforced by precipitation of elements released by weathering as has often been suggested at other locations honeycomb weathering develops rapidly and can be observed on surfaces that were planar less than a century ago

water absorption and p wave velocity changes during freeze thaw weathering process of crosscut travertine rocks the turkish travertine is widely used in the domestic and foreign construction industry as slabs and tiles in this study the travertine samples were obtained from four different quarries located in the part of southwestern turkey mineralogical and petrographic properties of the travertine rocks were studied using a polarizing optical microscope and sem the laboratory tests mechanical and physical properties capillary water absorption freeze thaw f t process p wave velocity were performed according to technical specification european standard ts en standards the pore size distribution was determined by means of high pressure mercury porosimetry mip the most of the pores 80 of tested travertine have a pore access diameter of 0 1 m some engineering properties of the rock are severely affected by f t cycles such as ultrasonic p wave velocities water absorption weight and strength the porosity of the travertine presents significantly higher values after the cycles of freeze thaw which also leads to the increase in the absorption by immersion the water absorption method showed that water absorption weight of the specimens varied from 0 32 to 0 88 after the 25 period the freeze and thaw effects of the samples which were tested after exposing to water were measured at a certain time the obtained dry saturated and frozen p wave velocities were examined by the changes of four travertine samples p wave velocity increase is in the range of 4 99 5 97 for tested travertine rocks these studies explain that the p wave velocity changes in freezing travertine exclusively due to changing velocities of pore infill i e water air and ice

a three dimensional back analysis of the collapse of an underground cavity in soft rocks abstract the assessment of stability of man made underground caves excavated in the past and later on abandoned represents a serious challenge for land and urban planning operations especially for the areas of possible interaction of the caves with overlying structures and infrastructures several areas of southern italy are characterized by the presence of abandoned underground quarries for the extraction of soft calcarenite rocks which now threatens the overlying environment due to the risk of collapse and the consequent generation of sinkholes this work presents a back analysis of a sinkhole occurred in 2011 in the town of marsala caused by the collapse of an underground quarry as a representative case study of these phenomena based on the available geometrical and geological dataset as well as the field observations of the phenomenon in this article the assumptions and the results about the genesis of the 2011 sinkhole as derived from a three dimensional finite element back analysis aimed at reconstructing the stress strain evolution that brought to the ground failure collapse is discussed in particular the 3 d numerical analyses have been performed in order to identify the factors responsible of the genetic mechanism of the sinkhole the finite element analysis has been carried out by accounting for the geotechnical characterization of the marsala calcarenites derived from both specific laboratory tests performed on samples taken from the site and literature data available on the same rock material the numerical results have been then validated by means of the comparison with field observations and also compared with those achieved through a 2 d model of the same case study

diagenetic processes influencing porosity in sandstones from the triassic buntsandstein of the iberian range spain abstract sandstones of the triassic buntsandstein of spain were studied in an attempt to quantify effects of diagenetic processes such as compaction cementation and leaching on reservoir properties samples were taken from shell well siguenza 44 3 some 110 km northeast of madrid drilled on the siguenza high in the iberian range the sandstones are arkoses to sublitharenites of a typical triassic redbed facies characteristic of the whole region the present day depth of the base buntsandstein is 538 m whilst a maximum burial depth of ca 2600 m was estimated from vitrinite reflectance 0 94 to 1 14 kaolinite temperature 76 c and illite crystallinity kuebler index 4 9 from an estimated average initial porosity of 38 porosity was reduced to the present value of 13 the strongest process to reduce porosity was found to be mechanical compaction causing a loss of 15 followed by chemical compaction pressure solution with a loss of about 6 the cement 11 4 r v apparently reduced the initial porosity by about only 5 early carbonate and sulphate cements are interpreted to have stabili sed the rock framework working against mechanical compaction and pressure solution this is supported by an increase in sutured grain contacts where early cements are absent or rare the later quartz cement interpreted to be largely the product from pressure solution has reduced porosity in a ratio of 0 5 1 this suggests that compaction continued after the formation of the late quartz cement although leaching was observed especially in feldspar grains clay and k feldspar neomorphosis is interpreted to have counteracted the formation of substantial secondary porosity permeability in the buntsandstein is generally low average 17 4 md and has been strongly affected by the alteration of feldspars to clay causing a wide range of permeability from 0 11 to 73 0 md

diagenetic replacement controlled by force of crystallization many diagenetic replacements in sedimentary rocks occur along thin solution films between the authigenic and host phases rather than conventionally invoking bulk pore water undersaturation for host phase dissolution we propose that many diagenetic replacements occur by a force of crystallization controlled replacement mechanism whereby nonhydrostatic stresses resulting from authigenic crystal growth are principally responsible for host phase dissolution this model explains diagenetic features such as the restriction of host phase dissolution to authigenic host crystal contacts and euhedral authigenic crystal faces in planar contact with unreplaced host phases as well as the relative replacement tendencies of some common authigenic minerals

characterizing large river history with shallow geophysics middle yukon river yukon territory and alaska abstract changes in longitudinal valley fill thickness can provide inferences about fluvial behaviour over millennia increased thickness of channel deposits may reveal climate induced accelerated sediment supply basin subsidence tectonic displacements or rising downstream base level decreases in thickness expressed as terraces may suggest active uplift decreased sediment flux or falling base level within a reach to date methods to characterize valley fills have depended largely on borehole data however recent developments in shallow geophysics make such investigations possible and provide a practical methodology to investigate alluvial rivers we carried out a longitudinal geophysical survey coupled with floodplain chronologies to characterize a 1000 km reach of the middle yukon river between western yukon territory and central alaska ground penetrating radar gpr and electrical resistivity ground imaging ergi profiles along the middle yukon river between central yukon and alaska coupled with channel bottom echo profiles demonstrates that there is little variation in thickness of gravel fill and depth of active scour holes gpr surveys near the white river the largest sediment source in the upper yukon show no significant longitudinal variation in gravel thickness 8 16 m up to near circle alaska 530 km of wandering channels geophysical profiles across the yukon flats sedimentary basin 430 km of braided and wandering channels show an increase in gravel thickness 25 30 m but this is consistent with compaction of underlying lacustrine sediment and maximum depths of contemporary scour holes from the western margin of the yukon flats to the dalton highway bridge 30 km confined valley with no floodplain or braid bars borehole data at the bridge indicates 6 10 m of gravel on bedrock beneath 3 6 m of water floodplain stratigraphy indicates there is little evidence of fluvial aggradation of the middle yukon during the holocene radiocarbon ages from the gravel overbank silt contact near present river level demonstrate a general vertical stability of the river with a period of rapid eolian accumulation during the late pleistocene and early holocene the consistency of gravel fill and scour hole depth and lack of holocene terraces along the 1000 km reach of the yukon indicate that the river has been in a state of mass balance equilibrium of sediment transport input output over the holocene despite massive sediment influxes from the glacial fed white river and crossing major faults variation in valley fill depth is not significant and further the yukon flats reach shows no evidence of bed aggradation during the pleistocene and has probably existed in equilibrium since the late pliocene

convective vortices and dust devils at the phoenix mars mission landing site 1 the phoenix mars lander detected a larger number of short 20 s pressure drops that probably indicate the passage of convective vortices or dust devils near continuous pressure measurements have allowed for monitoring the frequency of these events and data from other instruments and orbiting spacecraft give information on how these pressure events relate to the seasons and weather phenomena at the phoenix landing site here 502 vortices were identified with a pressure drop larger than 0 3 pa occurring in the 151 sol mission ls 76 to 148 the diurnal distributions show a peak in convective vortices around noon agreeing with current theory and previous observations the few events detected at night might have been mechanically forced by turbulent eddies caused by the nearby heimdal crater a general increase with major peaks in the convective vortex activity occurs during the mission around ls 111 this correlates with changes in midsol surface heat flux increasing wind speeds at the landing site and increases in vortex density comparisons with orbiter imaging show that in contrast to the lower latitudes on mars the dust devil activity at the phoenix landing site is influenced more by active weather events passing by the area than by local forcing

petrographic quantification of brecciated rocks by image analysis application to the interpretation of elastic wave velocities abstract this paper presents a new procedure to quantify the petrology of materials with complex and heterogenic rock fabric features the classical methodologies for petrographic quantification by image analysis are not appropriate for this kind of rock due to both the high chromatic complexity of these materials and the scale with which the samples are studied the proposed process is particularly interesting for materials with complex chromatic characteristics such as highly fractured rocks concrete etc two commercial varieties of highly fractured brecciated dolostones were selected for this study in order to test the designed methodology this new procedure is based on the analysis process of colour images obtained from mesoscopic sample scanning six petrographic parameters and diagrams have been designed in order to quantify the most influential aspects in compressional v p and shear v s ultrasonic wave propagation these petrographic parameters and diagrams are brecciation density brecciation density map clast size distribution fine grained matrix content shape preferred orientation and rose diagrams the results demonstrate that the proposed methodology is suitable for quantifying the petrography of these kinds of materials furthermore the variations measured in v p and v s are fully explained by the values measured for the following parameters brecciation density fine grained matrix content clast size distribution and preferred orientation of clasts

fracture geometry of pseudotachylyte generation zones a study of shear fractures formed during seismic events abstract the orientation and movement sense of shear fractures in pseudotachylyte generation zones developed in the ikertoq shear belt west greenland are described and the fracturing sequence is inferred the generation zones occur in strongly foliated gneisses and consist of concordant usually paired principal displacement shear fractures paired shears on which most melt was generated and a system of minor shear fractures minor shear fracturing was most intense between principal displacement shear fractures and most melt intruded from these paired shears inwards with respect to the zone intrusion of injection veins of pseudotachylyte off the principal displacement shear fractures is believed to be contemporaneous with minor shear fracturing in the generation zones generation zones affect intact rocks and individual principal displacement shear fractures have a maximum displacement of 4 6 m paired principal displacement shear fractures are up to 3 m apart and have a maximum observed length of 1 km in all the zones described the fracturing appears to be the result of a single episode of slip both dextral and sinistral generation zones occur within the study area and have different geometries in each case the displacement is strike slip

rocky coast geomorphology and erosional processes a case study along the murgia coastline south of bari apulia se italy many sites along the apulian coast se italy are composed of weathered and fractured carbonate rocks affected by intense erosion and the development of slope instabilities here coastal morphology was mostly produced by quaternary tectonics the severe and selective action of modern erosion by sea waves and locally was strongly conditioned by human influences in addition due to the carbonate nature of rock masses the role exerted by karst processes has to be considered this paper provides a critical review of the common eroding processes and factors affecting coastal morphology in a typical mediterranean coastal carbonate environment a stretch of the murgia coastline south of bari between san vito and polignano a mare made up of cliffs and shore platforms interrupted by small pocket beaches was considered for qualitative and quantitative assessment of shoreline recession the coastal stretch was monitored by means of field surveys between 1997 and 2003 furthermore a comparison of vertical aerial photographs covering the period 1966 1997 scales 1 33 000 1 10 000 and 1 5000 topographic maps scales 1 5000 year 1987 1 2000 year 1982 and archival terrestrial photographs taken since the 1930s was also employed in some zones characterised by a gently sloping shore platform a significant shoreline retreat was calculated at about 20 m in the last 100 years 0 2 myr 1 which was caused above all by human activity here in fact the presence of small ancient coastal quarries

atmospheric entry profiles from the mars exploration rovers spirit and opportunity abstract accelerometer measurements made by spirit and opportunity during their entries through the martian atmosphere are reported vertical profiles of atmospheric density pressure and temperature with sub km vertical resolution were obtained using these data between 10 and 100 km spirit s temperature profile is 10 k warmer than opportunity s between 20 and 80 km unlike all other martian entry profiles spirit s temperature profile does not contain any large amplitude long wavelength oscillations and is nearly isothermal below 30 km opportunity s temperature profile contains a strong inversion between 8 and 12 km a moderate dust storm which occurred on mars shortly before these two atmospheric entries may account for some of the differences between the two profiles the poorly known angle of attack and unknown wind velocity may cause the temperature profiles to contain errors of tens of kelvin at 10 km but these errors would be an order of magnitude smaller above 30 km on broad scales the two profiles are consistent with mars global surveyor thermal emission spectrometer tes pressure temperature profiles differences exist on smaller scales particularly associated with the near isothermal portion of spirit s profile and the temperature inversion in opportunity s profile

measurement of martian boundary layer winds by the displacement of jettisoned lander hardware abstract martian boundary layer wind speed and direction measurements from a variety of locations seasons and times are provided for each lander sent to mars over the last four decades a unique record of the winds blowing during their descent is preserved at each landing site by comparing images acquired from orbiting spacecraft of the impact points of jettisoned hardware such as heat shields and parachutes to a trajectory model the winds can be measured we start our investigations with the viking lander 1 mission and end with schiaparelli in between we extract wind measurements based on observations of the beagle 2 spirit opportunity phoenix and curiosity landing sites with one exception the wind at each site during the lander s descent were found to be 1 high speed winds were required to explain the displacement of jettisoned hardware at the phoenix landing site we found a tail wind 20 m s 1 blowing from the north west was required at a high altitude 2 km together with a gust close to the surface our findings are consistent with a turbulent pbl in the afternoon and calm pbl in the morning when comparing our results to a gcm we found a good match in wind direction but not for wind speed the information provided here makes available wind measurements previously unavailable to mars atmosphere modellers and investigators

dune formation under bimodal winds the study of dune morphology represents a valuable tool in the investigation of planetary wind systems the primary factor controlling the dune shape is the wind directionality however our understanding of dune formation is still limited to the simplest situation of unidirectional winds there is no model that solves the equations of sand transport under the most common situation of seasonally varying wind directions here we present the calculation of sand transport under bimodal winds using a dune model that is extended to account for more than one wind direction our calculations show that dunes align longitudinally to the resultant wind trend if the angle w between the wind directions is larger than 90 under high sand availability linear seif dunes are obtained the intriguing meandering shape of which is found to be controlled by the dune height and by the time the wind lasts at each one of the two wind directions unusual dune shapes including the wedge dunes observed on mars appear within a wide spectrum of bimodal dune morphologies under low sand availability

the mars limited area model and simulations of atmospheric circulations for the phoenix landing area and season of operation 1 the mars limited area model mlam has been used to simulate martian northern polar atmospheric circulation phenomena during the planned season of the phoenix lander touching down on the surface ls 76 initial and boundary conditions are from thermal emission spectrometer observations assimilated via the united kingdom mars general circulation model the higher resolution north pole centric nestings grid lengths about 17 30 km and 8 5 15 km respectively resolve phenomena such as shallow mesoscale katabatic drainage flows spiraling out of the cold polar dome strong valley winds out of chasma borealis and diurnal slope winds embedded on the easterly basic flow e g at phoenix landing area d there conditions appear to be mild for mars and baroclinic activity is low low level jets with wind speeds exceeding 20 m s are however possible but they are most likely nocturnal and would hence not endanger the early afternoon landing of phoenix dust lifting is predicted for strong wind areas near the landing area b where baroclinic activity appears to be high and in the general area of the landing area d primarily east of it

tafoni on coastal slopes south devon u k cavernous weathering tafoni development occurs on coastal slopes in greenschist bedrock at elevations up to 40 m above sea level the freshly weathered surfaces of the cavern interiors are irregular in morphology discordant to major rock structure formed by substantially weakened rock and associated with granular weathering debris the weathering debris contains soluble elements in proportions similar to those present in seawater and the penetration of elements associated with sea salts into the weathering surface to estimated depths of at least 0 1 0 2 m is indicated by the presence of chlorine scanning electron microscopy and microprobe analyses suggest that rock breakdown occurs principally through limited chemical weathering at grain boundaries the mechanism for the emplacement of marine salts within sheltered rock surfaces in the tafoni is postulated to be a combination of dry deposition under turbulent atmospheric conditions and wetting by coastal fog

rheology of the lithosphere selected topics we review recent results concerning the rheology of the lithosphere with special attention to the following topics 1 the flexure of the oceanic lithosphere 2 deformation of the continental lithosphere resulting from vertical surface loads and forces applied at plate margins 3 the rheological stratification of the continents 4 strain localization and shear zone development and 5 strain induced crystallographic preferred orientations and anisotropies in body wave velocities we conclude with a section citing the 1983 1986 rock mechanics literature by category

the control of mineral constituents and textural characteristics on the petrophysical mechanical pm properties of different rocks of the himalaya abstract petrophysical and mechanical pm properties of a rock are primarily controlled by its mineral constituents and various textural parameters similar rock types in different tectonic setups may be characterized by different mineralogical compositions and textural properties because they might have suffered different deformational processes this paper presents a study on the mineralogical and textural control on various pm properties in quartzites granitoids gneisses metabasics and dolomite collected from different tectonic set ups the inter relationships among mineral constituents various textural parameters unconfined compressive strength ucs schmidt hammer rebound r value seismic wave both p and s waves velocity and their attenuation characteristics were obtained using regression analyses it has been concluded that there exists no relation between ucs and seismic wave velocity in quartzite granitoids and gneisses moderate positive relationship in metabasics and strong negative relationship in dolomite it has further been noted that in quartzite and dolomite monominerelic rocks grain size dominantly control the seismic wave velocity as the relatively coarser grained samples have higher seismic wave velocity whereas ucs is strongly controlled by grain size as well as the quantity and the orientation of the weak minerals like muscovite biotite calcite etc in gneisses and granitic gneisses preferred orientation of minerals especially the mica minerals although in present small quantity is the main factor controlling ucs and seismic velocity both these properties increase with the increase in intensity of preferred alignment of minerals whereas in metabasics it is the presence of amphibole pyroxene minerals feldspar that dominantly controls the seismic wave velocity

dynamic response of a rocky cliff under the sea wave pulse a study along the adriatic coast of polignano apulia italy the dynamic behavior of a rocky cliff under severe sea waves has been analyzed in the location of polignano facing on the adriatic coast of apulia southern italy in this area the classical and at the same time complex problem of the stability of a cliff in calcareous rocks is burdened by the presence on the top of the cliff of the ancient town to analyze the behavior of the cliff under the impulsive transfer of energy generated by the sea waves two types of measures were carried out on the rocky mass 1 ambient noise and 2 strong motion records the first type of measures which may be executed in a short time with a high spatial density has provided a recognition of the intrinsic and anisotropic dynamic behavior of the coastal cliff the accelerometric records carried out during heavy storms in december 2009 and january 2010 allowed to evaluate the energy transfer from waves to cliff in terms of maximum values and temporal and directional distribution to facilitate a correct interpretation of the measures also a geomechanical characterization of the rocky mass has been carried out through the rock mass rating system bieniawski the geomechanics classification in rock engineering applications proceedings of the 4th isrm cong montreux pp 51 58 1979 bieniawski engineering rock mass classifications wiley new york p 251 1989 and the markland s test a useful technique for estimating the stability of rock slopes when the rigid wedge sliding type of failure is expected pp 10 1972 the first allowed to classify the rocky masses in terms of quality the second one to individuate the potential failure mechanisms of the cliff

petrographic features influencing basic geotechnical parameters of carbonate soft rocks from apulia southern italy abstract a multidisciplinary petrographic and geotechnical approach aimed at understanding the conditioning by rock fabric on the mechanical properties of carbonate soft rocks is shown in this paper the analysed rocks extensively crop out in the apulia region and can be referred to three geological units pietra leccese late burdigalian early messinian calcarenite di gravina middle pliocene early pleistocene and salentino supersynthem midde late pleistocene 69 specimens of carbonate soft rocks belonging to all these units were selected from different sectors of apulia region and characterized according to petrographic physical and mechanical properties petrographic data allowed us to group all specimens in the following six classes i wackestone ii mud dominated packstone iii packstone iv grainstone v floatstone vi rudstone differently uniaxial compression strength ucs values classify the most part of specimens in very low and low strength revealing a dominant weak resistance and high deformability particular attention has been given to the relationships between petrographic features and physical and mechanical parameters of the apulian soft rocks by means of statistical tests based on the univariate analysis of variance one way anova and on the principal component analysis pca at first statistical analysis revealed that the rock geotechnical values are strictly dependent from the geological units particularly the samples of pietra leccese show significantly higher means of ucs young s modulus et and dry unit weight than samples of the calcarenite di gravina fm conversely samples of this latter unit have significantly higher means of porosity imbibition coefficient and permeability coefficient than those ones of the pietra leccese fm moreover statistical analysis was applied to estimate if geotechnical values differ according to the petrographic classes of the calcarenite di gravina fm and to verify the covariance between the geotechnical parameters of this unit the following results have been remarked i floatstone and rudstone have significantly higher means of ucs and dry unit weight and lower means of porosity than finer grained classes ii mud dominated packstone has significantly lower means of ucs dry unit weight et and permeability coefficient and higher means of porosity and imbibition coefficient than other petrographic classes iii grain dominated matrix free rudstone and grainstone have significantly higher values of permeability coefficient than mud dominated classes iv the occurrence of carbonate lithoclasts and of different dominant couples of sparry cement in pore spaces are two of the most important controlling factors of the rock strength and can also explains much of the intraformational variability observed in geotechnical data total porosity has not a clear correlation with permeability this means that the contribution of isolated pore spaces to the total porosity is relevant in apulian soft rocks as also suggested by the relatively low values of permeability compared to the relatively high percentages of total porosity a multidisciplinary characterization of carbonate soft rocks based on petrographic analysis and geotechnical determination of physical and mechanical properties is here recommended for future studies since this approach can give useful information to understand the peculiar behaviour of carbonate soft rocks and to drive the subsequent geotechnical investigations

a preliminary analysis of failure mechanisms in karst and man made underground caves in southern italy abstract natural and anthropogenic caves may represent a potential hazard for the built environment due to the occurrence of instability within caves that may propagate upward and eventually reach the ground surface inducing the occurrence of sinkholes in particular when caves are at shallow depth the effects at the ground surface may be extremely severe apulia region southern italy hosts many sites where hazard associated with sinkholes is very serious due to presence of both natural karst caves and anthropogenic cavities the latter being mostly represented by underground quarries the pliocene pleistocene calcarenite a typical soft rock was extensively quarried underground by digging long and complex networks of tunnels with time these underground activities have progressively been abandoned and their memory lost so that many apulian towns are nowadays located just above the caves due to urban expansion in the last decades therefore a remarkable risk exists for society which should not be left uninvestigated the present contribution deals with the analysis of the most representative failure mechanisms observed in the field for such underground instability processes and the factors that seem to influence the processes as for example those causing weathering of the rock and the consequent degradation of its physical and mechanical properties aimed at exploring the progression of instability of the cavities numerical analyses have been developed by using both the finite element method for geological settings represented by continuous soft rock mass and the distinct element method for jointed rock mass conditions both the effects of local instability processes occurring underground and the effects of the progressive enlargement of the caves on the overall stability of the rock mass have been investigated along with the consequent failure mechanisms in particular degradation processes of the rock mass as a consequence of wetting and weathering phenomena in the areas surrounding the caves have been simulated the results obtained from the numerical simulations have then been compared with what has been observed during field surveys and a satisfactory agreement between the numerical simulations and the instability processes as detected in situ has been noticed

mass balance of glaciers and ice caps consensus estimates for 1961 2004 1 working with comprehensive collections of directly measured data on the annual mass balance of glaciers other than the two ice sheets we combine independent analyses to show that there is broad agreement on the evolution of global mass balance since 1960 mass balance was slightly below zero around 1970 and has been growing more negative since then excluding peripheral ice bodies in greenland and antarctica global average specific balance for 1961 1990 was 219 112 kg m 2 a 1 representing 0 33 0 17 mm sle sea level equivalent a 1 for 2001 2004 the figures are 510 101 kg m 2 a 1 and 0 77 0 15 mm sle a 1 including the smaller greenland and antarctic glaciers global total balance becomes 0 38 0 19 mm sle a 1 for 1961 1990 and 0 98 0 19 mm sle a 1 for 2001 2004 for 1991 2004 the glacier contribution 0 77 0 26 mm sle a 1 is 20 30 of a recent estimate of 3 2 0 4 mm a 1 of total sea level rise for 1993 2005 while our error estimates are not rigorous we believe them to be liberal as far as they go but we also discuss several unquantified biases of which any may prove to be significant

geology geography and humans battle for dominance over the delivery of fluvial sediment to the coastal ocean abstract sediment flux to the coastal zone is conditioned by geomorphic and tectonic influences basin area and relief geography temperature runoff geology lithology ice cover and human activities reservoir trapping soil erosion a new model termed bqart in recognition of those factors accounts for these varied influences when applied to a database of 488 rivers the bqart model showed no ensemble over or underprediction had a bias of just 3 across six orders of magnitude in observational values and accounted for 96 of the between river variation in the long term 30 years sediment load or yield of these rivers the geographical range of the 488 rivers covers 63 of the global land surface and is highly representative of global geology climate and socioeconomic conditions based strictly on geological parameters basin area relief lithology ice erosion 65 of the between river sediment load is explained climatic factors precipitation and temperature account for an additi

suspended sediment and carbonate transport in the yukon river basin alaska fluxes and potential future responses to climate change 1 loads and yields of suspended sediment and carbonate were measured and modeled at three locations on the yukon tanana and porcupine rivers in alaska during water years 2001 2005 1 october 2000 to 30 september 2005 annual export of suspended sediment and carbonate upstream from the yukon delta averaged 68 mt a 1 and 387 gg a 1 respectively with 50 of the suspended sediment load originating in the tanana river basin and 88 of the carbonate load originating in the white river basin about half the annual suspended sediment export occurred during spring and half occurred during summer autumn with very little export in winter on average a minimum of 11 mt a 1 of suspended sediment is deposited in floodplains between eagle alaska and pilot station alaska on an annual basis mostly in the yukon flats there is about a 27 loss in the carbonate load between eagle and yukon river near stevens village with an additional loss of about 29 between stevens village and pilot station owing to a combination of deposition and dissolution comparison of current and historical suspended sediment loads for tanana river suggests a possible link between suspended sediment yield and the pacific decadal oscillation

quantitative mineralogy of the yukon river system changes with reach and season and determining sediment provenance the mineralogy of yukon river basin sediment has been studied by quantitative x ray diffraction bed beach bar and suspended sediments were analyzed using the rockjock computer program the bed sediments were collected from the main stem and from selected tributaries during a single trip down river from whitehorse to the yukon river delta during the summer of 2001 beach and bar sediments were collected from the confluence region of the tanana and yukon rivers during the summer of 2003 suspended sediments were collected at three stations on the yukon river and from a single station on the tanana river at various times during the summers of 2001 through 2003 with the most complete set of samples collected during the summer of 2002 changes in mineralogy of yukon river bed sediments are related to sediment dilution or concentration effects from tributary sediment and to chemical weathering during transport carbonate minerals compose about 2 wt of the bed sediments near whitehorse but increase to 14 wt with the entry of the white river tributary above dawson thereafter the proportion of carbonate minerals decreases downstream to values of about 1 to 7 wt near the mouth of the yukon river quartz and feldspar contents of bed sediments vary greatly with the introduction of pelly river and white river sediments but thereafter either increase irregularly quartz from 20 to about 50 wt or remain relatively constant feldspar at about 35 wt with distance downstream clay mineral content increases irregularly downstream from about 15 to about 30 wt the chief clay mineral is chlorite followed by illite smectite there is little to no kaolinite the total organic carbon content of the bed sediments remains relatively constant with distance for the main stem generally 1 to 2 wt with one exception but fluctuates for the tributaries 1 to 6 wt the mineralogies of the suspended sediments and sediment flow data were used to calculate the amount of mineral dissolution during transport between eagle and pilot station a distance of over 2000 km we estimate that approximately 3 wt of the quartz 15 wt of the feldspar 1 wt of the alkali and 25 wt of the plagioclase and 26 wt of the carbonates 31 wt of the calcite and 15 wt of the dolomite carried by the river dissolve in this reach the mineralogies of the suspended sediments change with the season for example during the summer of 2002 the quartz content varied by 20 wt with a minimum in mid summer the calcite content varied by a similar amount and had a maximum corresponding to the quartz minimum these modes are related to the relative amount of sediment flowing from the white river system which is relatively poor in quartz but rich in carbonate minerals suspended total clay minerals varied by as much as 25 wt with maxima in mid july and suspended feldspar varied up to 10 wt suspended sediment data from the summers of 2001 and 2003 support the 2002 trends a calculation technique was developed to determine the proportion of various sediment sources in a mixed sediment by unmixing its quantitative mineralogy results from this method indicate that at least three sediment sources can be identified quantitatively with good accuracy with this technique sediment mineralogies can be used to calculate the relative flux of sediment from different tributaries thereby identifying sediment provenance

controls on the geotechnical response of sedimentary rocks to weathering weathering reduces the strength of rocks and so is a key control on the stability of rock slopes recent research suggests that the geotechnical response of rocks to weathering varies with ambient stress conditions resulting from overburden loading and or stress concentrations driven by near surface topography in addition the stress history experienced by the rock can influence the degree to which current weathering processes cause rock breakdown to address the combined effect of these potential controls we conducted a set of weathering experiments on two sedimentary lithologies in laboratory and field conditions we firstly defined the baseline geotechnical behaviour of each lithology characterising surface hardness and stress strain behaviour in unconfined compression weathering significantly reduced intact rock strength but this was not evident in measurements of surface hardness the ambient compressive stress applied to samples throughout the experiments did not cause any observable differences in the geotechnical behaviour of the samples we created a stress history effect in sub sets of samples by generating a population of microcracks that could be exploited by weathering processes we also geometrically modified groups of samples to cause near surface stress concentrations that may allow greater weathering efficacy however even these pronounced sample modifications resulted in insignificant changes in geotechnical behaviour when compared to unmodified samples the observed reduction in rock strength changed the nature of failure of the samples which developed post peak strength and underwent multiple stages of brittle failure although weakened these samples could sustain greater stress and strain following exceedance of peak strength on this basis the multi stage failure style exhibited by weaker weathered rock may permit smaller magnitude higher frequency events to trigger fracture through intact rock bridges as well as influencing the characteristics of pre failure deformation these findings are consistent with patterns of behaviour observed in field monitoring results

fluvial sediment flux to the arctic ocean the paper presents an overview of recent publications on the fluvial suspended sediment flux to the arctic ocean the total suspended matter exported from the russian territory is 102 10 6 t year and from the canadian arctic is 125 10 6 t year the total suspended matter tsm flux to the arctic 227 10 6 t year is very low only about 1 of the global flux mean concentrations of suspended matter and specific sediment discharge are approximately one order of magnitude lower than the global concentration an analysis of the trends in the sediment loads based on records of up to 62 years in length shows decreases yenisey increases kolyma and stability ob among the reasons for the very low concentrations and fluxes of suspended sediment in the arctic rivers are thin weathering crusts on the arctic watersheds low precipitation extensive permafrost low temperatures for most of the year large areas of swamps and lakes and a low level of human activity a stochastic sediment transport model by morehead et al morehead m d syvitski j p hutton e w peckham s d 2003 modeling the temporal variability in the flux of sediment from ungauged river basins glob planet change 39 95 110 is applied to the arctic rivers to estimate the sediment load increase should the surface temperature of the drainage basin increase for every 2 c of warming a 30 increase in the sediment flux could result and for each 20 increase in water discharge a 10 increase in sediment load could follow based on this model an increase of the sediment flux of six largest arctic rivers yenisey lena ob pechora kolyma and severnaya dvina is predicted to range from 30 to 122 by 2100

rock fabric heterogeneity and its influence on the petrophysical properties of a building limestone lede stone belgium as an example lede stone is an important historical stone in belgium with many ceased and disappeared historical quarries owing to its geological nature this stone exhibits considerable variation in petrophysical properties three macroscopical different facies from the solely remaining quarry area in balegem belgium were profoundly characterized for their pore network properties and petrophysical properties the pore network was exhaustively studied combining water imbibition under vacuum mercury intrusion porosimetry and x ray computed microtomography the three facies not only have a strong difference in total porosity but also differ in terms of pore connectivity and pore size distribution linked to the variability in microfacies this has profound implications on the water transfer properties such as atmospheric water absorption capillary water absorption om nidirectional drying and water vapor resistance the petrophysical behavior is illustrated with a salt ageing test the results can be used for restoration and conservation of lede stone in the built cultural heritage

interpretation of subsurface hydrocarbon shows hydrocarbons occur in the subsurface in four modes 1 continuous phase oil or gas 2 isolated droplets of oil or gas 3 dissolved hydrocarbons and 4 associated with kerogenous rocks all of these modes of occurrence can result in what is described as a subsurface hydrocarbon show each show type has markedly different implications to exploration and must be differentiated as the first step in show interpretation only continuous phase occurrences of oil and gas indicate that a trapped and potentially producible accumulation of hydrocarbons has been discovered free oil or gas recovery from the formation or subsurface hydrocarbon saturations of greater than 55 indicates a continuous phase occurrence continuous phase shows can be interpreted quantitatively the static hydrocarbon column downdip from a continuous phase occurrence can be calculated from one well bore if the subsurface oil or gas saturation capillary properties hydrocarbon water interfacial tension oil density and water density of the reservoir are known producing wells are by definition continuous phase oil or gas and estimates of oil water or gas water contacts from normally available exploration data are practical and reasonably accurate based on a documented field study continuous phase oil or gas can extend either updip or downdip from a commercial reservoir these continuous phase shows can also be interpreted quantitatively to determine how large an oil or gas column is required downdip to explain the show by this method it can be determined whether an exploratory well penetrated the updip waste zone or downdip transition zone of an oil or gas field field studies illustrate that quantitative show interpretation of noncommercial shows can provide reliable estimates of the downdip hydrocarbon column this type of data can be used in a systematic manner to explore for subtle stratigraphic and combination traps

a preliminary scanning electron microscope study of honeycomb weathering of sandstone in a coastal environment honeycomb weathering has been observed in a carboniferous sandstone at a coastal location near ballycastle on the north coast of northern ireland specimens of this sandstone have been analysed by x ray diffraction scanning electron microscopy and energy dispersive spectrometry results reveal that calcium sulphate gypsum is the only salt present and is found only at and immediately below the rock surface sem observations suggest that crystallization of salts in pores could easily dislodge quartz grains to promote granular disintegration whilst etching of quartz grain surfaces attests to chemical weathering activity within the rock however the reason for the development of the honeycomb pattern is not known

increased groundwater to stream discharge from permafrost thawing in the yukon river basin potential impacts on lateral export of carbon and nitrogen 1 arctic and subarctic watersheds are undergoing climate warming permafrost thawing and thermokarst formation resulting in quantitative shifts in surface water groundwater interaction at the basin scale groundwater currently comprises almost one fourth of yukon river water discharged to the bering sea and contributes 5 10 of the dissolved organic carbon doc and nitrogen don and 35 45 of the dissolved inorganic carbon dic and nitrogen din loads long term streamflow records 30 yrs of the yukon river basin indicate a general upward trend in groundwater contribution to streamflow of 0 7 0 9 yr and no pervasive change in annual flow we propose that the increases in groundwater contributions were caused predominately by climate warming and permafrost thawing that enhances infiltration and supports deeper flowpaths the increased groundwater fraction may result in decreased doc and don and increased dic and din export when annual flow remains unchanged

sandstone degradation an experimental study of accelerated weathering the investigated rock material belongs to the group of upper cretaceous quader sandstones which are very important construction stones in poland and germany the mineral composition of the rocks is relatively uniform they are quartzose sandstones the most important feature is their good workability and comparatively high weathering resistance still regardless of the apparent resemblance the observations carried on buildings and monuments show differences in weathering processes the undertaken test was an attempt to verify the proposed before rock classification performed on the basis of parameterization of porosimetric cumulative intrusion volume curves the aim of the experiment was the evaluation of the sandstone petrography including the structure texture and porosity of the rock influence on the weathering process the modelling of accelerated weathering was conducted in chamber for ageing acceleration where some weather circumstances were simulated insolation rain and frost as the result of the weathering experiment it could be stated that the dominant mechanism of the sandstones deterioration was granular disintegration and weight loss as a consequence of sample destruction the most important factor influencing rock deterioration is rock texture especially the character of grain contacts the effective porosity is a requisite of potential for the stone to take in and hold water and hence of resistance to weathering in case of silica cemented sandstones the deciding criterion influencing weathering resistance is pore structure in case of sandstones with clay cement the most important is mineral composition of the rock

experimental investigation on the performance of schmidt hammer test in durability assessment of carbonate building stones against freeze thaw weathering although schmidt hammer test has been widely used for assessment of weathering state of rocks its application for evaluation of rock durability remains rare this study aims at investigating the performance of the schmidt hammer test in the durability assessment of carbonate building stones against frost weathering for this purpose nine types of carbonate rocks were collected from various quarries of iran and subjected to a series of tests including determination of petrographical physical mechanical ultrasonic and rebound hardness properties moreover long term weathering test of freeze thaw up to 100 cycles were carried out and ultrasonic detection was used to detect the weathering induced damages of rocks in ultrasonic detections ultrasonic parameters of maximum amplitude amax spatial attenuation s and compressional wave velocity vp were determined before and after freeze thaw tests and then their change rates were determined the change rates of amax s and vp including ka k and kp respectively were considered as the functions of the degree of the frost induced damages of rocks and consequently as indications of the rock durability results showed that there are close correlations between the schmidt hammer rebound value rn and ka k and kp however the correlation between rn and kp was weaker than those between rn and ka and k because of the disproportionate response of vp to the rock deterioration it was concluded that the schmidt hammer test is capable to evaluate the durability of carbonate building stones and can be used for a rapid and onsite evaluation of rock durability at different quarry faces hence it allows selecting more durable rocks for different applications in new constructions and also in replacement works in historical sites

susceptibility mapping of instability related to shallow mining cavities in a built up environment anthropogenic activities and urbanization frequently spread over areas underlain by unstable karst ground or man made cavities leading to potential risk situations for buildings infrastructure and population the roof of the cavities may rapidly propagate upwards eventually resulting in progressive ground settlement and or sudden collapse these processes are frequently accelerated or triggered by various human activities e g overloading water recharge water table decline in this paper the susceptibility to instability of artificial cavity networks under an urban area in apulia region southern italy was assessed and evaluated here there is dense network of underground quarries excavated for the extraction of massive calcarenite for building and ornamental stone that are currently affected by severe instability problems identifying the zones of the cavities most prone to instability is of great practical importance susceptibility models have been developed analyzing the statistical relationships between the cavity sections with evidence of instability and a number of predisposing factors mainly related to the 3d geometry of the voids roof thickness and the presence of overloads the models produced by the discriminant analysis and the logistic regression approaches were independently and quantitatively evaluated through the construction of roc curves although the two models are characterized by different input data treatment as the logistic regression allows using continuous and discrete variables or any combination of both types even if they do not have a normal distribution the roc curves highlighted for both methods a satisfactory congruence between the model results and the observed data consequently from the model performance analysis the two models were evaluated comparable in terms of result reliability the methodology should be considered as a general first level analysis for near surface underground cavities aimed at identifying critical cave sectors that can be the focus of more detailed analyses especially those associated with sensitive zone related to the presence of buildings roads and frequent presence of human activity

an image analysis technique to measure grain size variation in thin sections of soft clastic sediments this paper presents a simple and fast image analysis technique to measure grain size variation in thin sections of soft elastic sediments optical and backscattered electron microscope photographs are digitised from thin sections cut by freeze drying to avoid disturbing the sediments processing of the 256 grey scale images produces binary black and white images where white pixels represent the clay rich sedimentary matrix and black pixels represent elastic grains data measured include grain surface grain perimeter and centre of gravity two indices are defined to quantify grain size d 0 equivalent disk diameter and p phase percentages the technique is applied to silt and clay laminations attributed to the d division of a distal turbidite from lake baikal the data obtained using image analysis are similar to the conventional descriptions of such deposits indices calculated on very small samples e g on a single lamina allow for greater precision in interpretation of sedimentary processes compared to photomicrographs backscattered electron microscope images have better qualities and allow to quantify variations in the grain size along a sediment core the technique produces objective and quantified grain size observations in less time than conventional petrographic methods c 1998 elsevier science b v all rights reserved

the brittle deformation regime of water saturated siliceous sandstones summary we present here new experimental data on the mechanical behaviour of water saturated bentheim and fontainebleau sandstones deformed in the brittle failure regime bentheim sandstone samples were stressed at room temperature and subjected to confining pressures pc ranging from 12 to 120 mpa and pore pressures pp ranging from 1 to 70 mpa for all samples the evolution of the volumetric strain first shows compaction eventually reversing to dilation of the pore volume when approaching the peak stress all samples failed localized on a single shear zone critical stresses that is onset of dilatancy and peak stress can be uniquely defined as a function of the effective pressure peff pc pp the failure curve parameters when fitted with the hoek brown criterion or a parabolic envelope are consistent with previous values obtained on similar material when compared to data obtained on dry samples of the same rock the present data show no notable effect of the presence of water on the critical stress levels the same conclusion holds for the stress strain curves when dry and water saturated experiments under equivalent effective confining pressures are compared when compared to previously published data obtained on various quartzose rocks which show a quite variable water weakening effect our results lead to the conclusion that the quasi exclusive presence of quartz grains bonded together by a quartzose cement combined with the absence of clayey minerals may explain the absence of this effect in bentheim sandstone moreover this conclusion is supported by complementary results obtained by fontainebleau sandstone with similar microstructural and compositional characteristics a previously developed micromechanical model based on the interaction of pore cracks has been used and modified to take into account the presence of water when compared to the experimental data the results of the model show good agreement for low to intermediate effective confining pressures critical stresses as well as deformation curves are well reproduced as was the case for the dry rock provided that effective pressure is introduced at higher effective pressures a mix of mechanisms including shear enhanced compaction may explain the progressive discrepancy between the modelled and the experimental curves when approaching the apex of the failure envelope

on the technical properties of the carovigno stone from apulia italy physical characterization and decay effects by means of experimental ageing tests apulia southern italy is typified by widespread outcrops of rocks exploited in the last centuries in historical architectures and religious constructions as building and decorative stone today as in the past these stones represent an important source for region economy and prestige due to their uses for modern works restoration of local medieval churches and also exporting abroad among these a noteworthy and still poorly known material is the carovigno stone in this paper firstly an overall view on the mineralogical and petrophysical features of the stone was reached through a multianalytical approach based on several investigation procedures and techniques including ultrasonic test x ray diffractometry scanning electron microscopy optical microscopy mercury intrusion porosimetry in order to simulate decay phenomena the carovigno stone samples were processed to three different ageing tests cycles of thermal treatments at different high temperatures cycles of heating cooling and cycles of exposure to decahydrate sodium sulphate and sodium chloride saline solutions during and after each ageing processes mineralogical transformations and petrophysical changes were evaluated results suggested that the carovigno stone is a fine grained calcarenite pure or nearly pure characterized by high porosity and consequently very notable thermal stress resistance conversely the type and amount of porosity causes stone predisposition to salt crystallization decay

rapid wastage of alaska glaciers and their contribution to rising sea level we have used airborne laser altimetry to estimate volume changes of 67 glaciers in alaska from the mid 1950s to the mid 1990s the average rate of thickness change of these glaciers was 0 52 m year extrapolation to all glaciers in alaska yields an estimated total annual volume change of 52 15 km 3 year water equivalent equivalent to a rise in sea level sle of 0 14 0 04 mm year repeat measurements of 28 glaciers from the mid 1990s to 2000 2001 suggest an increased average rate of thinning 1 8 m year this leads to an extrapolated annual volume loss from alaska glaciers equal to 96 35 km 3 year or 0 27 0 10 mm year sle during the past decade these recent losses are nearly double the estimated annual loss from the entire greenland ice sheet during the same time period and are much higher than previously published loss estimates for alaska glaciers they form the largest glaciological contribution to rising sea level yet measured

the effects of spatial resolution and dimensionality on modeling regional scale hydraulics in a multichannel river as modeling capabilities at regional and global scales improve questions remain regarding the appropriate process representation required to accurately simulate multichannel river hydraulics this study uses the hydrodynamic model lisflood fp to simulate patterns of water surface elevation wse depth and inundation extent across a 90 km anabranching reach of the tanana river alaska to provide boundary conditions we collected field observations of bathymetry and wse during a 2 week field campaign in summer 2013 for the first time at this scale we test a simple raster based model s capabilities to simulate 2 d in channel patterns of wse and inundation extent additionally we compare finer resolution 25 m 2 d models to four other models of lower dimensionality and coarser resolution 100 500 m to determine the effects of simplifying process representation results indicate that simple raster based models can accurately simulate 2 d in channel hydraulics in the tanana also the fine resolution 2 d models produce lower errors in spatiotemporal outputs of wse and inundation extent compared to coarse resolution 1 d models 22 6 cm versus 56 4 cm rmse for wse and 90 versus 41 critical success index values for simulating inundation extent incorporating the anabranching channel network using subgrid representations for smaller channels is important for simulating accurate hydraulics and lowers rmse in spatially distributed wse by at least 16 as a result better representation of the converging and diverging multichannel network by using subgrid solvers or downscaling techniques in multichannel rivers is needed to improve errors in regional to global scale models

atmospheric dynamics at the phoenix landing site as seen by the surface stereo imager 1 the surface stereo imager has made observations of dust blowing aloft and clouds near the horizon at the phoenix landing site these subtle features are apparent because of the high signal to noise ratio of the camera which allows for the removal of a mean frame from multiple images captured in rapid succession and the ability to conduct simultaneous capture through different filters in each camera eye by examining the ratios between two filters it was possible to determine in a relative sense how the water ice content of the atmosphere changed over the mission and on a diurnal time scale the direction of travel and speed of features aloft near the zenith has been inferred and agree well with the diurnal pattern of near surface wind direction from the telltale direct observation of cumulus like cloud near the surface suggests convection of water vapor rich air but only until midday requiring a mechanism to inhibit cloud formation in the early afternoon the spectral ratios agree well with the observation of cloud and indicate a general increase in water ice toward the end of the mission as well as a strong diurnal pattern however even in periods of high water ice content there is still a great deal of variability and days when dense clouds are absent also different cloud layers are occasionally observed moving in different directions indicating occasional wind shear aloft features observed had estimated minimum optical depths up to 0 11

physical properties and textural parameters of calcarenitic rocks qualitative and quantitative evaluations abstract petrophysical and mechanical properties of sedimentary rocks are influenced by size shape and packing of grains porosity cement and matrix content all controlled strongly by depositional fabric and postdepositional processes this paper presents a study on the textural characteristics of soft and porous calcarenites and the main methods to determine petrophysical data the examined calcarenites sampled from three quarry districts located in apulia southeastern italy are fine grained and coarse grained grainstones a and d and medium grained packstones b belonging to a plio pleistocenic formation calcarenite di gravina outcropping in the whole region the study involved particularly textural analysis on thin sections using optical petrographic microscopy and evaluation of total and effective porosity by means of standard geotechnical laboratory tests mercury intrusion porosimetry and image analysis grain size frequency distribution was also carried out by traditional sieve and sedimentation analysis on disaggregated materials and image analysis computer analysis of digital images was performed on photomicrographs applying the methods of quantitative stereology to pore size and grain size distributions a comparison between results showed that each technique used has its limitations linked to the textural characteristics primarily geometry and topology of the pore network granulometry grain shape and packing of calcarenites

the pore system of sedimentary rocks as a key factor in the durability of building materials abstract we studied the pore system of six different types of sedimentary stone two limestones two sandstones one dolostone and one travertine techniques based on the direct observation of the pore system optical and scanning electron microscopes digital image analysis were combined with others used for indirect characterization mercury intrusion porosimetry n 2 adsorption hydric tests and vapour permeability in addition we performed accelerated decay tests to determine the durability of the stones and to check the consistency of the results obtained in the pore system study digital image analysis allowed us to calculate the pore size distribution and the total porosity digital image analysis always gave higher values for total porosity than those determined by porosimetry and hydric tests which only measure open porosity the density values were congruent with the mineralogy of the stones the stone that obtained the best results in the various tests in terms of its petrophysical parameters was dolostone while the worst performance was by one of the two limestones these results were confirmed by the decay tests the combined use of these different techniques gave us an accurate interpretation of the pore systems of the six different stones and also enabled us to correct misleading interpretations caused by the limitations of using one single technique our findings also provide useful information to help prevent the decay of these stones

role of clay minerals in the physicomechanical deterioration of sandstone 1 extensive weathering suffered by sandstone in natural outcrops as well as in historical buildings could be attributed among other mechanisms to the action of wetting and drying cycles we have recently shown how to quantify the stresses generated during such cycles to determine whether damage can take place this procedure is further developed in this paper and applied to the tarifa sandstone a sandstone with a 7 wt content of clay minerals and used in the main facade of the church of san mateo in tarifa cadiz spain for which the relevant material properties are measured it is shown that tensile stresses during drying can cause cracking of thin elements and that shear forces can cause buckling of wetted surfaces more generally eventually resulting in scaling and or contour scaling these predictions are supported by visual observations on the monument showing degradation patterns characteristic of those types of damage similar weathering forms have been observed in natural sandstone landscapes application of swelling inhibitors e g cationic surfactants that selectively adsorb on the clay basal planes results in a substantial swelling reduction this confirms that the swelling clays typically present in sandstone are pivotal for its weathering and indicates that swelling inhibitors are a potentially valuable treatment to prevent or minimize damage to stone the circumstances that would lead to weathering are discussed in relation to sandstone material properties in the wet and dry state clay bearing stones are shown to exhibit softening during wetting as well as viscoelastic stress relaxation which is expected to limit the extent of damage these results may aid in the better understanding of sandstone weathering both in nature and in urban environment and may help develop conservation methods to mitigate wetting drying damage in ornamental sandstone or to prevent pore plugging in reservoir sandstones

sea level changes since the middle ages along the coast of the adriatic sea the case of st nicholas basilica bari southern italy abstract during the last decade several papers have been published to estimate the relative sea level change from coastal archaeological indicators of the last 3 4 ka bp in many locations of the italian coasts and the mediterranean sea the use of the archaeological information has been poorly focused for the middle ages due to the few available coastal installations for this period thus not allowing precise sea level estimation for the last 1000 years to complement the instrumental data available for the last 100 120 years this study discusses an archaeological marker of the middle ages used to reconstruct the story of the sea level changes in the last 1000 years at the st nicholas basilica built in 1087 ad along the coast of bari apulia southern italy the elevations of the ancient floor levels of the crypt underwent repeated flooding due to a continuous rising of the groundwater table which required restoration and uplifting of pavements between 1087 and 1956 to keep them dry the palaeo sea levels have been obtained by measuring the position of the groundwater table the elevation of which is mainly driven by sea level since the time of the construction of the basilica the elevation of the archaeological markers and the water table were compared against the latest predicted sea level curve for the holocene along the coast of bari as this coastal area is unaffected by significant vertical tectonic motion over the last 125 ky the data detail the timing of the relative sea level rise since the middle ages and can be used to improve the predicted sea level curve for this region for the last 1000 years

petrography and reservoir physics i objective classification of reservoir porosity porosity observed in thin section can be objectively classified using a combination of digital acquisition procedures and pattern recognition algorithms pore types are derived from the frequency distributions of sizes and shapes of patches of porosity exposed in thin section each pore type is represented by a characteristic distribution of sizes and shapes found in thin section most sandstone reservoirs contain fewer than six pore types much of the intersample variability in reservoir physics is associated with changes in pore type abundance the advantages of this approach to porosity classification are 1 the criteria for classification are objectively defined 2 classification procedure is rapid accurate and precise 3 pore types are understood easily in ter s of conventional genetic classification schemes and 4 pore type data are related strongly to petrophysical properties

a visual determination method for uniaxial compressive strength estimation based on croatian carbonate rock materials abstract to identify visually detectable elements that influence carbonate rock strength a detailed inspection of 231 samples mainly from the adriatic carbonate platform in croatia was conducted prior to laboratory testing anova was used to detect statistically significant carbonate rock material parameters that influence ucs lithology fabric defects and porosity lfdp and their optimal classes anova was also used to find a statistically significant model that contains four major effects on the strength of carbonate rock lfdp with three two way interactions lithology fabric fabric defects and defects porosity according to four basic influential parameters the new procedure is coined lfdp determination and is described in detail the presented results indicate that the lfdp determination method is reliable enough for use in engineering geological practice on croatian carbonate rocks but also for use in other regions while the presented method may be applied to other regions worldwide its suitability to local conditions should be tested the lfdp determination method is simple efficient inexpensive and versatile it can be applied to outcrops cuts quarries tunnels borehole cores and similar however it is important to note that this method cannot replace laboratory testing and should be only used to collect preliminary information on carbonate rock material properties and possible ranges in ucs values

the influence of rock fabric in the durability of two sandstones used in the andalusian architectural heritage montoro and ronda spain abstract natural stone has been a popular and reliable building material throughout history appearing in many historic monuments and in more recent buildings research into the intrinsic properties of specific stones is important because it gives us a greater understanding of the factors that limit and act on them this can help prevent serious problems from occurring in our buildings bringing both esthetic benefits and financial savings to this end the main objective of this research has been to study the influence of the fabric and the mineral composition of two types of sandstone on their durability the first is a red continental sandstone from the buntsandstein age called molinaza roja which is quarried in montoro cordoba the second is quarried in ronda malaga and is sold under the trade name of arenisca ronda it is a light pink whitish calcarenite deposited during the late tortonian to late messinian we characterized their petrological and petrophysical properties by studying their rock fabrics porous systems and mechanical properties in order to obtain a complete vision of the behavior of their rock fabrics we also carried out two decay tests the salt crystallization and the freeze thaw tests we then measured the effects on the textures of the altered samples during and after the decay tests and we evaluated the changes in the porous system by comparing the results between intact and altered samples we found that arenisca ronda is less durable because it has a high quantity of expandable clays smectites and a high percentage of pores in the 0 1 1 m range in which the pressure produced by salt crystallization is strongest in molinaza roja the decay agents caused significant sanding due to loss of cohesion between the clasts especially during the salt crystallization test in both stones the anisotropies oriented textures have an important role in their hydric and dynamic behavior and also affect their mechanical properties especially in the compression resistance no changes in color were detected

the influence of the characteristics of quartz and mineral deterioration on the strength of granitic dimensional stones it is important to have a thorough knowledge of the petrographic characteristics of rocks to evaluate and understand their mechanical behavior this paper deals with the influence of the texture and the mineral characteristics of nine portuguese granites employed as dimensional stones this study evaluates different mineral characteristics such as mineral deterioration grain size quartz fissuration and the contacts between quartz and others mineral groups the main differences in the studied granites were identified clarifying the relationship between the petrographic characteristics the consequences on their respective mechanical behavior were subsequently evaluated the physical and textural characteristics of quartz in the studied granites have proven to be very important for understanding the behavior of granitic rocks under compressive stress uniaxial compressive strength values are not proportional to the quartz feldspar ratio or quartz content and there is a tendency for strength to decrease with the increase in quartz this could be related to the increase in quartz quartz contacts and the decrease in the rock capacity for accommodating the deformation