thermal decay of carbonate dimension stones fabric physical and mechanical changes this paper deals with the effects of thermal stresses on selected carbonate rocks used as dimension stones they are mesozoic calcareous and dolomitic rocks cropping out in apulia southern italy that for their physico mechanical and aesthetic properties have always been finding a large application both as ornamental stones and as simple construction materials their use is attested not only in italy in works of archaeological historical and artistic interest too the cause effect relationships of thermal degradation were studied by means of an artificial accelerated ageing test in order to provide a perspective about the decay of carbonate stones due to diurnal and seasonal temperature fluctuations as well as thermal shocks during events of fire development the stone samples were subjected to thermal cycles in a muffle furnace ranging from 100 to 700 c after each cycle several non destructive and semi destructive tests were carried out mass and volume measurements mercury intrusion porosimetry sclerometer tests ultrasonic tests thin section observations and determination of chromatic alterations through image analysis and munsell charts method in this way the qualitative and quantitative modifications induced in fabric physical and mechanical properties were discussed the results highlight the fundamental role of depositional and diagenetic fabric that together with mineralogical composition represents the most significant discriminating factor in the response of the stone to thermal stresses

miocene gypcretes from the calama basin northern chile gypcretes of miocene age are preserved beneath a 9 53 0 36 ma ignimbrite along the eastern margin of the oligo pleistocene calama basin northern chile they are restricted to a single stratigraphic horizon developed within laterally extensive 35 km coalesced alluvial fan deposits developed along the margin of an endorheic basin two types of gypcrete are recognized type 1 comprises almost completely gypsum cemented sandstones containing alabastrine nodules and columns sub vertical and horizontal veins of fibrous gypsum and v shaped cracks infilled by clastic material and are interpreted as surface weathered gypsic crusts type 2 gypcretes are composed of massive reddened poikilitic and mesocrystalline gypsum up to 80 of the rock with isolated bedding parallel clast rich lenses 200 30 cm and sub vertical veins of fibrous gypsum the massive texture resembles that of well developed b horizons in quaternary alluvial desert soils the crystal forms suggest an origin as a subsurface gypsic crust formed by a combination of hydromorphic poikilitic and illuvial mesocrystalline processes with the fibrous gypsum veins suggestive of periodic surface exposure gypcrete horizons are up to 25 m thick and composed of both gypcrete types they represent superimposed phases of surface and subsurface gypcrete development quaternary gypcretes are developed in arid climatic regimes but are not considered to develop under hyper arid climates an arid climate is considered to have prevailed in the study area up to 9 5 ma after which a change to hyper aridity favoured gypcrete preservation

extensive carbonate algal bioherms in upper pleistocene saline lakes of the central altiplano of bolivia during the upper pleistocene the central altiplano of bolivia was repeatedly flooded by deep and extensive saline lakes in response to climatic fluctuations development of carbonate algal bioherms took place during at least three major periods of lacustrine highstands discontinuously covering the 300 km long and 100 km wide lacustrine slopes and terraces up to an elevation of 100 m above the surface of the modern halite crust of uyuni distribution size and shape of the bioherms are diverse due to various factors e g the nature and morphology of the substrate and the hydrodynamic conditions that prevailed during growth on larger palaeoterraces the build ups coalesced to form platform like carbonate accumulations although the morphologies closely resemble those induced by cyanobacteria they were predominantly constructed by other plant communities probably dominated by filamentous green algae cyanobacterial communities flourished in association with these plants but they did not contribute significantly to the architecture of the bioherms they participated to encrust the plant stems and algal bushes or to form thin laminated layers covering the build ups a prominent feature of some bioherms is their composite structure due to repeated algal growth during successive lacustrine episodes that were separated by subaerial exposures with moderate erosional effects the build ups located between 3660 and 3680 m elevation display up to three major parts 1 a massive inner core formed during an early minchin highstand before 40 ka 2 a large peripheral envelope deposited at about 40 ka late minchin and 3 a thinner outermost crust formed during a late glacial event lake level dropped during interlacustrine stages sometimes leading to desiccation and deposition of salt layers in the deepest parts of the system i e the present day salar of uyuni

broad synchrony of a late glacial glacier advance and the highstand of palaeolake tauca in the bolivian altiplano the morphology and sedimentology of glacially influenced fan deltas on massifs at the margin of the southern altiplano bolivia suggest a broadly synchronous expansion of glaciers and palaeolake tauca during the late glacial interval this is shown by sedimentary successions of glacigenic glacifluvial and glacideltaic facies linking palaeoglaciers with palaeolake tauca on the flanks of cerro azanaques and cerro tunupa at altitudes of 3770 3720 m radiocarbon dates from peat overlain by glacial diamict and glacifluvial outwash indicate that glaciers in this area reached their last glacial maximum extent after ca 13 300 14 c yr bp glacifluvial fan deltas contiguous with the moraines confirm that the advance coincided with a highstand of palaeolake tauca radiocarbon dated to the interval ca 13 500 11 500 yr bp modeling of climatic controls on this glacier advance suggests the primary forcing was increased summer wet season moisture possibly amounting to 600 mm above the modern values of 200 400 mm greater cloud cover probably depressed local temperatures and reduced the evaporation rate the consequent rise in effective annual moisture p e comfortably accommodates a palaeolake 48 50 10 3 km 2 in area and up to 100 m deep in the southern altiplano because the palaeoglacier equilibrium line altitudes rose toward the south and west like the gradient of modern precipitation totals we conclude that the increased late glacial moisture was brought by weather systems similar to those of the present but that atmospheric conditions were cloudier and cooler 1997 john wiley sons ltd

climate and lake level history of the northern altiplano bolivia as recorded in holocene sediments of the rio desaguadero abstract strata exposed in terraces and modern cutbanks along the rio desaguadero contain a variety of lithofacies that were deposited in four distinct facies associations these facies associations document a history of aggradation and downcutting that is linked to holocene climate change on the altiplano braided stream meandering stream deltaic and shoreline and lacustrine sediments preserved in multi level terraces in the northern rio desaguadero valley record two high water intervals one between 4500 and 3900 yr bp and another between 2000 and 2200 yr bp these wet periods were interrupted by three periods of fluvial downcutting centered at approximately 4000 yr bp 3600 yr bp and after 2000 yr bp braided river sediments preserved in a single terrace level in the southern rio desaguadero valley record a history of nearly continuous fluvial sedimentation from at least 7000 yr bp until approximately 3200 yr bp that was followed by a single episode post 3210 yr bp of downcutting and lateral migration the deposition and subsequent fluvial downcutting of the northern strata was controlled by changes in effective moisture that can be correlated to holocene water level fluctuations of lake titicaca the deposition and dissection of braided stream sediments to the south are more likely controlled by a combination of base level change and sediment input from the rio mauri

salt crystallization in pores quantification and estimation of damage the objective of this study is to understand and predict the alteration of porous rock by crystallization of salts samples of different rocks have been tested according to the en 12370 standard test two parameters are proposed to evaluate the alteration of a rock during these tests the alteration index ai represents the cycle in which the first damages occur the alteration velocity av represents the alteration rate at the end of the experiment when the decay has become regular these parameters can be estimated with the help of a microstructural study of the rocks the most relevant intrinsic parameters of the stones for this estimation are capillary coefficient evaporation coefficient tensile strength and p waves velocity an evaluation of the alteration pattern is also proposed depending on the eventual heterogeneities and anisotropies of the rocks the influence of the dimension and shape of the samples is also discussed

granitic dimensional stones in uruguay evaluation and assessment of potential resources in uruguay commercial granite varieties comprise mafic rocks granitoids and syenitoids there is a long tradition in uruguay as well as worldwide of using dimensional stones in architecture and art specially granitic ones some of the present applications of these dimensional stones are as facade cladding countertops and outdoor and indoor floor slabs the color spectrum of the uruguayan granitic dimensional stones varies from black to light gray covering a wide variety of red and pink and minor greenish gray the decor of these granitic dimensional stones is mainly determined by their fabric fundamentally the grain size and the color distribution between the different minerals that compose the rocks in the present research the most important commercial granites were sampled to analyze their petrography and petrophysical properties a detailed structural analysis has been performed in several deposits as well as the application of the software 3d block expert for modeling the possible raw block size distribution other factors controlling the mining viability of the deposits were also studied e g homogeneity heterogeneity of color and decor and the possible reserves were calculated

origins of wind driven intraseasonal sea level variations in the north indian ocean coastal waveguide 1 in this paper we show that a linear continuously stratified ocean model reproduces observed wind driven intraseasonal sea level variability in the coastal waveguide of the northern indian ocean nio sensitivity experiments with intraseasonal wind forcing selectively applied in the equatorial region bay of bengal and arabian sea show that a large part of the basin scale sea level variations are driven by zonal wind fluctuations along the equator within the nio coastal waveguide the contribution of remote equatorial forcing decreases from 80 90 in the andaman sea to 50 northeast of sri lanka and then increases to 60 70 along the west coast of india during the southwest monsoon intraseasonal wind variations become stronger over the nio resulting in a larger contribution of local wind forcing to sea level variability along the west up to 60 and east up to 40 coasts of india

intraseasonal variability in the upper layer currents observed in the eastern equatorial indian ocean 1 direct observations of the upper ocean velocity in the eastern equatorial indian ocean by an acoustic doppler current profiler from november 2000 to october 2001 on the equator at 90 e demonstrate that the dominant periods of variability in the upper layer zonal and meridional currents are in intraseasonal frequency bands with periods of 30 to 50 days and 10 to 20 days respectively the strong intraseasonal variability in the zonal current obscures the semiannual wyrtki jets which can be seen clearly in the monthly averaged field in addition a zone of strong vertical shear of the zonal current and a distinct equatorial undercurrent with semiannual period are observed the results provide us with a new perspective on importance of the energetic intraseasonal variability in the eastern equatorial indian ocean which indicates strong correlation with the wind variability near the mooring location

influence of fracture system on the exploitation of building stones the case of the mondim de basto granite north portugal the most negative aspects in the exploitation of weathered granites as ornamental stones tend to be heterogenic coloration and fracturing therefore an accurate study is needed for a comprehensive evaluation of the granite resources during an exploration campaign this paper presents the results of the fracturing evaluation of a region located in north of portugal where the mondim de basto granite a stone with a high weathering degree is exploited the regional fracturing was evaluated from lineaments in aerial photos and then compared with local jointing in quarries the jointing in each quarry is characterized according to the strike and dip joint spacing and volumetric joint count two indices were proposed to facilitate the jointing comparison among quarries the joint space length ljs and joint set spacing sjs ljs is based on the sum of all the spacing values obtained perpendicularly to the strike direction sjs is computed based on the overall mean median spacing and on the number of joint sets observed in each quarry the most important joint sets in the subdivision of the rock mass were found not to be in accordance with the regional fracturing patterns highlighting the necessity of studying the fracturing at all scales

high ground water levels and dune development in central australia tl dates from gypsum and quartz dunes around lake lewis napperby northern territory abstract an episode of high lake levels prior to the last maximum glaciation has been identified at many localities in wastern australia similar events have been recognized at playa lakes in central australia where gypsum dunes along playa margins formed during one or more episodes of high groundwater discharge with a large influx of calcium sulphate at lake lewis exposures at two islands show similar sediment sequences three pedogenic gypcrete layers interbedded with aeolian quartz and gypsum sand horizons form three units within gypsum dunes up to 7 m high the lowest unit has cliffed edges buried by the upper units indicating a significant time break four tl dates coarse grained quartz show that this lowest unit was deposited at or before 70 80 ka the middle unit of mixed gypsum and quartz sand capped by gypcrete represents the major phase of gypsum dune formation and 6 tl dates range from 33 to 46 ka with overlapping error bars these are slightly younger but statistically similar to tl dates from 39 to 59 ka of the shoreline gypsum dune at lake amadeus in the same region the top unit of the two islands up to 1 m thick has not yet been well dated one date is inconsistent with the well dated middle layer below possibly because of incomplete bleaching and has been rejected the other date 17 5 ka is much younger which possibly indicates a minor and local reactivation of old gypsum sediments at the lake margin there are quartz dunes overlying the gypsum dunes and a buried aeolian quartz sand layer occurs in a lake margin terrace these represent reactivation of the regional quartz dune field after the major gypsum dune formation two consistent tl dates 21 4 ka and 23 6 ka indicate that regional dunes were active at about the time of the last glacial maximum

an analysis of tropical instability waves in a numerical model of the pacific ocean 2 generation and energetics of the waves this work was supported by the department of com merce noaa under grant na56gp0026 one of the au thors sm was partially supported by a nasa global change fellowship ngt 30288 another author ab was supported by a ucar postdoctoral fellowship

bromine geochemistry of salar de uyuni and deeper salt crusts central altiplano bolivia abstract the salar of uyuni in the central bolivian altiplano is probably the largest salt pan in the world 10 000 km 2 a 121 m deep well drilled in the central salar disclosed a complex evaporitic sequence of 12 salt crusts separated by 11 mud layers in the lower half of the profile thick halite beds alternate with thin mud layers the mud layers thicken upwards and show clear lacustrine features the thickness of the salt beds decreases markedly from the base upward the bromine content of the halite ranges from 1 3 to 10 4 mg kg the halite does not originate from the evaporation of the dilute inflow waters of the altiplano which would lead to br content of tens of mg kg the presence of halite of very low br content 2 mg kg in a gypsum diapir strongly suggests that most of the halite deposited at uyuni originated from the leaching of ancient salt formations associated with the numerous gypsum diapirs of the altiplano the deep and thick halite beds were probably deposited in a playa lake as suggested by their very low and fairly constant br content 1 6 2 3 mg kg and by the abundance of detrital minerals thereafter perennial salt lakes of increasing duration flooded the central altiplano increasing amounts of dilute inflow waters of low cl br ratio and the exhaustion of diapiric halite lead to an increase of both the thickness of the lacustrine layers and of the bromine content of the salt crusts 5 10 mg kg deposited as the lakes dried up paleolake levels in the central altiplano rose as those in the northern altiplano the titicaca basin were simultaneously falling the progressive fluvial erosion of the threshold between the northern and the central altiplano lowered the levels of the northern lakes and allowed more dilute waters of low cl br ratio to flood the central altiplano therefore both the thickness of lacustrine sediments and the bromine content of the salt crust increased to the present the three upper crusts show a decrease in bromine content which may reflect a recent modification of the inflow regime to the last lakes the salt crust deposited by the last salt lake 10 000 years ago shows a bromine distribution that unexpectedly increases with depth as the lake dried the salt crust was probably initialy distributed over a wider area than the present flat crust covering the topographic surface up to the level of the lake where halite reached saturation the dissolution of the initial salt of low br content from the margins of the lake to the center is probably responsible for the observed br distribution in the surface salt as in a playa during the holocene a severe drought hit the altiplano and drastically lowered the intracrustal brine table within the salt crust leaving a thin layer of high concentrated residual brine at the bottom of the crust bromine rich halite replaced primary halite by a temperature activated mechanism in the lower crust further increasing the br gradient with depth

the determination of uniaxial compressive strength from point load strength for pyroclastic rocks abstract the point load test has often been reported as an indirect measure of compressive strength it has been used widely in practice due to easy testing the simplicity of specimen preparation and possible field applications many researchers have investigated the relation between uniaxial compressive strength ucs and point load index is for different rock types however there are limited studies in the literature for soft rocks such as pyroclastic rocks in this study the relation between ucs and is was investigated for pyroclastic rocks having ucs values are less than 50 mpa very strong exponential relations were found for dry rocks saturated rocks and both dry and saturated rocks the results were also compared to the studies in the literature

determination of strength parameters and quality assessment of denizli travertines sw turkey abstract travertine carbonate rich sedimentary rocks which are deposited by hot and cold waters as with all natural stones strength properties of travertines have great importance depending on the using conditions and places naturally porous structure of travertines is the most important parameter affecting the overall strength denizli basin is one of the world s major travertine regions in this study strength properties and relations between obtained parameters of denizli travertines were studied uniaxial compressive strength ucs values of travertines are widely ranging between 9 58 and 132 32 mpa noche type travertines are identified to have 59 100 higher strength than other type of travertines flexural strength under concentrated load 3 point flexural strength fls 3 and flexural strength under constant moment 4 point flexural strength fls 4 tests which are required for ce certification were also carried out on travertine samples between these tests linear relationship expressed as fls 4 0 98 fls 3 0 094 was found variations of strength parameters depending on the stone cutting type have been presented for the first time in this study it is found that the strength values under parallel loading to lamination are 1 44 times higher than the perpendicular loading

building stone evaluation a case study of the sub himalayas muzaffarabad region azad kashmir pakistan abstract building stone is one of the oldest material used in construction the present study evaluated the physical and mechanical characteristics of dolomite limestone and sandstone as building stones these rocks were selected from the foothills of himalaya as a case study compressive strength tensile strength specific gravity durability under wetting drying water absorption pulse velocity and petrography of the selected rocks were evaluated relationships were established among these properties of the rocks total reserves of these rocks in the selected area were approximated and the influence of geological structures on the rock properties were also considered kashmir boundary thrust and kawai fault present in the study area have adversely affected the physico mechanical characteristics of the rocks dolomite shows a higher water absorption and lower strength values than expected kamsar dolomite shows high degree of fracturing and weathering which lowers its polishing character and degrades its quality as building and ornamental stone however yadgar dolomite reflects fair degree of polishing and could be used as ornamental stone and as non load bearing masonry units limestone also shows lower strength values but its good degree of polishing and other characteristics are suggestive of its use in internal flooring cladding stone veneer wall stone tabletops risers and treads the most suitable rock proven as building stone is pattika sandstone due to its sound petrographic characters higher tensile and compressive strengths very high durability and lower water absorption values deolian sandstone should be avoid in load bearing masonry units because of its lower strength values pattika sandstone can be used as curbs copings sills facing stone external pavements and as ashlar and rubble stone strength properties were found to be largely dependent on each other ultrasonic pulse velocity in these rocks shows close relation to the density than the strength characteristics durability under wetting drying was found to be more relevant to the water absorption and less relevant to the strength of rocks sandstone has fairly large reserves in the study area followed by dolomite and limestone

a correlation between schmidt hammer rebound numbers with impact strength index slake durability index and p wave velocity the main objective of this study was to establish statistical relationship between schmidt hammer rebound numbers with impact strength index isi slake durability index sdi and p wave velocity these are important properties to characterize a rock mass and are being widely used in geological and geotechnical engineering due to its importance schmidt hammer rebound number is considered as one of the most important property for the determination of other properties like isi sdi and p wave velocity determination of these properties in the laboratory is time consuming and tedious as well as requiring expertise whereas schmidt hammer rebound number can be easily obtained on site which in addition is non destructive so in this study an attempt has been made to determine these index properties in the laboratory and each index property was correlated with schmidt hammer rebound values empirical equations have been developed to predict isi sdi and p wave velocity using rebound values it was found that schmidt hammer rebound number shows linear relation with isi and sdi whereas exponential relation with p wave velocity to check the sensitivity of empirical relations student s t test was done to verify the correlation between rebound values and other rock index properties

spatiotemporal structure of the east india coastal current from satellite altimetry we use a newly processed altimeter data set to present a hitherto unprecedented description of the spatiotemporal structure of the east india coastal current eicc the data set resolves timescales ranging from a few months to a few years and the high along track resolution yields the first description of the cross shore structure of the current the seasonal cycle dominates the variability but the nonannual timescales have similar energy levels all along the eicc path there are short lived intense intraseasonal bursts in contrast to the seasonal cycle the interannual and intraseasonal components are decorrelated along the coast and possible mechanisms for the decorrelation discontinuity in the flow are discussed in the cross shore direction the current is highly correlated at all timescales the eicc is trapped against the shelf with the current offshore flowing in the opposite direction at most locations the eicc appears as an inherently discontinuous flow taking the form of a few recirculating loops along the eicc path with a typical cross shore spatial scale of 150 200 km the loops are highly variable in direction at all timescales from intraseasonal to interannual this discontinuity of the eicc in space and time implies that the basic pathways and advective timescales for the interbasin exchange of water masses between the bay of bengal and the arabian sea are not robust when the full spatiotemporal variability of the eicc is considered

black dimensional stones geology technical properties and deposit characterization of the dolerites from uruguay dimensional stones with a black color occupy a prominent place on the international market uruguayan dolerite dikes of andesitic and andesitic basaltic compo sition are mined for commercial blocks of black dimen sional stones a total of 16 dikes of both compositions were studied and samples collected for geochemical and petro graphical analysis color measurements were performed on different black dimensional stones in order to compare them with the uruguayan dolerites samples of the two commercial varieties absolute black and moderate black were obtained for petrophysical analysis e g density porosity uniaxial compressive strength tensile strength etc detailed structural analyses were performed in sev eral quarries geochemistry and petrography determines the intensity of the black color the uruguayan dolerite absolute black is the darkest black dimensional stone analyzed in this study the petrophysical properties of uruguayan dolerites make them one of the highest quality black dimensional stones structural analyses show that five joint sets have been recognized two sub vertical joints one horizontal and two diagonal these joint sets are one of the most important factors that control the deposits since they control the block size distribution and the amount of waste material

aeolian landscapes in central australia gypsiferous and quartz dune environments from lake amadeus there are two different dune systems in central australia regional quartz dunefields and transverse gypsiferous dunes associated with playa lakes these two systems especially gypsiferous dunes at lake amadeus the largest playa in central australia provide a sedimentary geomorphological and environmental history of the region during the late quaternary the gypsifierous dunes consist of a surficial gypcrete overlying an aeolian sediment sequence below a mixture of gypsum sand and quartz sand no clay pellets have been found in the dune sequence in significant contrast to the gypsiferous clay dunes in other parts of australia three possible models of the environmental controls of gypsiferous dune formation are discussed the most plausible one suggests simultaneous gypsum precipitation and deflation sandsized gypsum was precipitated in a groundwater seepage zone around the playa margin during seasonally high water tables and these crystals were deflated onto land during dry intervals forming the marginal gypsiferous dunes these processes require conditions of high regional water table strong climatic seasonality and probably a windier and overall wetter climate at least two separate gypsiferous duneforming episodes can be recognized the age of formation of the younger one has been dated by thermoluminescence at 44 54 ka the gypcrete crust capping the dunes is characterized by intergrown microcrystalline gypsum crystals showing evidence of leaching dissolution and recrystallization it is interpreted as a pedogenic product formed during a stable period after accumulation of the gypsiferous dune after the construction of the younger gypsiferous dune there was a major episode of activation of regional quartz dunefields which formed thick quartz sand mantles overlying gypsiferous dunes on both playa margins and the dune islands within the playa an equivalent aeolian sand layer was deposited within the playa soil structures in this unit indicate that the sand sheet over the playa was later colonized by vegetation activation of the regional dunefields suggests a major period of dry climate which although not dated may correlate with the last glacial maximum identified as a period of maximum aridity from 25 to 18 ka at other sites in australia

quaternary geochemical evolution of the salars of uyuni and coipasa central altiplano bolivia risacher f and fritz b i99 i quaternary geochemical evolution ofthe salars of uyuni and coipasa central altiplano bolivia chem geol 90 21 1 231 the central trough of the bolivian altiplano is occupied by two wide salt crusts the salar of uyuni which is probably the largest salt pan in the world 10 000 km and the salar of coipasa 2 500 km both crusts are essentially made of porous halite filled with an interstitial brine very rich in li k mg b up to 4 7 g l li 4 3 g l b 30 g l k and 75 g l mg lithium reserves are the highest known in the world around 9x io6 tons potassium magnesium and boron reserves in brines are also important around 194x io6 tons k 8x 10 tons b and 21 1 x io6 tons mg the cnists are the remnant of saline lake tauca 13 000 10 000 yr bp its salinity was estimated approximately at 80 g l its paleochemistry was derived in two ways 1 by dissolving the present amounts of all chemical components in the former lake volume and 2 by simulating the evaporation of the major inflows to the basin the resulting chemical compositions are quite different the dissolution derived one is 5 to 50 times less concentrated in li k mg b than the evaporation simulated ones however all compositions present the same na and ci contents this suggests either a removal of bittern salts or an enrichment of the former lake water in na and ci the most probable interpretation is that lake tauca redissolved a salt crust akin to that existing today several older lakes have been detected on the altiplano nevertheless such an explanation only pushes the problem back it is likely that the anomaly was transferred from one lake to an other three hypotheses may be put forward 1 bittern seepage through bottom sediments 2 uptake of the missing components by minerals and 3 leaching of ancient evaporites from the catchment area at the beginning of the lacustrine history of the basin the excess halite could have been recycled from lake to lake this latter process seems to be the most effective to explain the large excess of na and ci over the bittern solutes li k mg and b the occurrence of almost pure na ci saline springs flowing out from a gypsum diapir in the northern altiplano gives substantial support to this hypothesis

characterization and quality assessment of granitic building stone deposits a case study of two different portuguese granites abstract several factors determine building stone exploration in order to maximize the extraction processing and application of these natural materials some factors are intrinsic to stones such as their physical mechanical properties while others are related to their exploitability such as quarry reserves or fracturing density during an exploration campaign these factors are not always considered or properly weighed in terms of the negative consequences on quarry activities or rock behaviour under particular conditions in this study two well known portuguese granites are assessed to highlight the main factors these granites have different characteristics weathered and sound and are exploited in quarries with different joint densities the most relevant physical mechanical properties were evaluated and related to the specific petrophysical features of each granite the fracture patterns were identified in the quarries and then modelled in order to compute the quarry yield the weathered granite shows an important microcrack network and a general alteration of the rock forming minerals which has an important impact on its physical mechanical properties and on the resistance to environmental factors moreover the extreme differences in the degree of weathering require careful choices for the possible applications in both quarries the joint sets are similar to the regional faulting but some random joints can be found and consequently diminish the quarry yield the development of horizontal sheet joints during the exploitation process could have a great influence on the quarry productivity if they are not used do delimitate the extracted blocks the modelling of the natural fracture pattern allows us to determine the potential volume of blocks that could be exploited however the quality of the information gathered could lead to an over estimation of the quarry production this example shows the importance of the exhaustive researches during a building stone assessment campaign

salt and ice crystallisation in porous sandstones salt and ice crystallisation in the pore spaces causes major physical damage to natural building stones the damaging effect of these processes can be traced back to physically induced stress inside of the rock while crystallizing the increasing scientific research done during the past century has shown that there are numerous parameters that have an influence on the weathering resulting from these processes however the working mechanisms of the stress development within the rock and its material dependency are still subject to discussion this article gives an overview of salt and ice weathering additionally laboratory results of various sandstones examined are presented salt crystallisation tests and freeze thaw tests were done to obtain information about how crystallisation weathering depends on material characteristics such as pore space water transportation and mechanical features simultaneous measuring of the length alternating during the salt and ice crystallisation has revealed detailed information on the development of crystal in the pore spaces as well as the development of stress these findings can help to understand the damaging mechanisms

mathematical models of vegetation pattern formation in ecohydrology 1 highly organized vegetation patterns can be found in a number of landscapes around the world in recent years several authors have investigated the processes underlying vegetation pattern formation patterns that are induced neither by heterogeneity in soil properties nor by the local topography are generally explained as the result of spatial self organization resulting from symmetry breaking instability in nonlinear systems in this case the spatial dynamics are able to destabilize the homogeneous state of the system leading to the emergence of stable heterogeneous configurations both deterministic and stochastic mechanisms may explain the self organized vegetation patterns observed in nature after an extensive analysis of deterministic theories we review noise induced mechanisms of pattern formation and provide some examples of applications relevant to the environmental sciences

physical weathering of building stones induced by freeze thaw action a laboratory long term study damages to natural building stones induced by the action of frost are considered to be of great importance commonly the frost resistance of building stones is checked by standardised freeze thaw tests before using corresponding tests normally involve 30 50 freeze thaw action cycles in order to verify the significance of such measurements we performed long term tests on four selected rocks over 1 400 freeze thaw action cycles additionally numerous petrophysical parameters were analysed to compare the behaviour of rocks in the weathering tests according to the current explanatory models of stress formation by growing ice crystals in the pore space the long term tests yield more information about the real frost sensibility of the rocks a clear deterioration cannot be determined in most cases until 50 weathering cycles have been completed in the freeze thaw tests the samples are also stressed by changing temperature and moisture indicating that different decay mechanisms can interfere with each other thus thermohygric and moisture expansion are important damage processes

evolution of a dune from crescentic to parabolic form in response to short term climatic changes rabjerg mile skagen odde denmark abstract rabjerg mile a complex parabolic dune reaches a height of 20 m above the deflation plain the width of the dune is 900 m and the length of the whole dune is 1500 m the dune is covered by 0 5 1 5 m high transverse dune ridges the dune has migrated approximately 1 km since 1887 a d accompanied by a change in the migration direction from ese 100 to ene 68 the morphology of rabjerg mile through the last 100 years is illustrated by a geographical information system arc info applied to a series of high quality topographical maps based on the digitized contour lines the evolution of rabjerg mile can be followed from an initial crescentic form in 1887 a d to a complex parabolic dune in this century dune dynamics and sites of erosion and deposition are evaluated from the digital terrain models changes in vegetation cover documented from the maps and air photos indicate that vegetation in the study area steadily increased with time calculations of resultant drift directions and gross bedform normal transport are based on climatic data from the skagen changed from an almost perfect transverse bedform 1887 1924 to an oblique imperfectly transverse bedform 1966 to present the bedform alignment followed the gross bedform normal transport rule in most years the evolution of a parabolic dune after 1924 is related to a period of reduced wind energy and increased vegetation cover this parabolic dune was maintained after 1960 when wind energy increased and the wind regime was more complex at the same time the dune became markedly asymmetric because of the frequent occurrence of strong southerly and easterly winds

granite fracture index to check suitability of granite outcrops for quarrying a correct knowledge of fracture patterns previous to quarrying is important for economical exploitation this work comprises the general characterization of the discontinuities of 10 granite rock masses in ne portugal during the study some discontinuity characteristics such as orientation persistence aperture trace length and spacing were evaluated the differences in the characteristics of the selected granites were described and the most important exploration factors were identified in the granites studied most of the joints are oriented from n10 e to n50 e which is compatible with the regional fracture pattern concerning joint termination the xx type is common while the rr type is rare the persistence index ranges from 3 5 to 25 4 closed joints are predominant in the granites studied n 72 4 and openings of the others are about 1 2 mm as a result of superficial displacement of the granite blocks the percentage of filled joints usually by quartz and pegmatite is different from one granite to another but most are b 20 the average joint length ranges from 11 1 m in post tectonics granites to 4 6 m in syntectonic granites joint spacing varies from 0 98 to 2 8 m with higher values in post tectonic granites joint space distributions of the granites studied are close to log normal and exponential distributions volumetric joint count jv ranges from 0 8 to 2 1 joints m 3 and is used for categorizing the places of each granite the relationships between jv and other joint characteristics such as length spacing and number of joint sets were investigated a granite fracturing index gfi is introduced computed on the basis of volumetric joint count number of joint sets and true joint spacing the gfi classification of studied places allows us evaluate the suitability for profitable exploitation 2007 elsevier b v all rights reserved

parabolic halite dunes on the salar de uyuni bolivia abstract palaeoenvironmental interpretation in desert and evaporitic sediments is often ambiguous consequently the recognition of primary sedimentary structures that indicate subaerial exposure or shallow marine conditions are therefore of crucial importance when interpreting marginal sedimentary evaporite facies parabolic halite dunes described here for the first time are observed on the salt crust of the largest salt flat in the world the salar de uyuni in bolivia the halite dunes are relatively small 0 7 1 3 m in width and length well defined lobate to hemicyclic parabolic dunes and are formed directly on the salt crust a model describing the formation and migration of the dunes in relation to brine level and climatic conditions is presented

late pleistocene climate and water budget of the south american altiplano abstract geomorphic evidence from the peruvian bolivian altiplano indicates that during episodes prior to 28 000 and around 12 500 11 000 yr b p lakes covered an area about six and four times as large as at present respectively within the constraints of the heat and water budget model calculations are used to estimate the precipitation rate that would allow hydrologic equilibrium on this basis it is suggested that rainfall on the altiplano during the episodes of enlarged lakes was respectively some 300 and 200 mm annum 1 larger than at present representing increases of about 75 and 50 respectively field evidence suggests that the episodes of enlarged lakes on the altiplano may have preceded or coincided with periods of maximum glaciation in the neigh boring andes in this region with high elevation of the ice equilibrium line increased precipitation is particularly conducive to glaciation

optimized extraction of dimension stone blocks the profitable production of dimension stone mainly depends on the extractable block size the regularity and volume of the blocks are of critical importance and are controlled by the three dimensional pattern of the discontinuity system therefore optimization of block size has to be the aim when quarrying for natural stone this is mainly connected to the quantification of joints and fractures i e their spacing and orientation the problem of finding unfractured blocks within arbitrarily oriented and distributed planes can be solved effectively by a numerical algorithm the main effects of joint orientations on block sizes and shapes will be presented in this article quantification of unfractured blocks with the aim of optimization is illustrated by detailed studies on several quarries the algorithm used in this study can be applied as a powerful tool in the planning of a quarry and the future exploitation of dimension stone application of the described approach is demonstrated on practical examples of quarrying natural stones namely sandstone granite rhyolite etc block quarrying can be optimized by using the new 3d blockexpert approach the quantification of unfractured rock masses is also shown to contribute to a more ecological protection and the sustainable use of natural resources

rock mass block quality designation for marble production abstract discontinuity spacing measurements are generally carried out along scan lines and or along the rock mass exposures quarry benches and or bore cores for assessing the rock mass quality rock mass block quality designation ratio bqd has been defined for assessment of the block production capacity of rock mass as bqd s 1m l where s 1m cumulative of the discontinuity spacing equal and or greater 1 0 m l scan line length m assessment of the discontinuity spacing measurements made along 2198 m long the scan lines in 6 working and five abandoned limestone quarries in karaburun area in western turkey have shown that while the working quarries had bqd ratios 50 and the abandoned quarries had bqd ratios

lake level chronology on the southern bolivian altiplano 18 23 s during late glacial time and the early holocene stratigraphic analyses of outcrops shorelines and diatoms from the southern bolivian altiplano uyuni coipasa basin reveal two major lacustrine phases during the late glacial period and the early holocene based on a chronology established by radiocarbon and u th control a comparison of14c and230th 234u ages shows that during times of high lake level radiocarbon ages are valid however during low water periods 14c ages must be corrected for a reservoir effect the lacustrine tauca phase started a little before 16 00014c yr b p and the lake level reached its maximum between 13 000 and 12 00014c yr b p a dry event ticana occurred after ca 12 000 and before 950014c yr b p a moderate lacustrine oscillation coipasa event occurred between ca 9500 and 850014c yr b p using a reservoir corrected conventional14c chronology comparisons between the lake level chronology in the uyuni coipasa basin and data from other southern tropical areas of south america suggest that the lacustrine evolution may reflect large scale climatic changes

eddy dynamics in a primitive equation model sensitivity to horizontal resolution and friction a primitive equation model of an idealized ocean basin driven by simple study wind and buoyancy forcing at the surface is used to study the dynamics of mesoscale eddies model statistics of a six year integration using a fine grid 1 6 0 2 with reduced coefficients of horizontal friction are compared to those using a coarser grid 1 3 0 4 but otherwise identical configuration eddy generation in both model cases is primarily due to the release of mean potential energy by baroclinic instability horizontal reynolds stresses become significant near the midlatitude jet of the fine grid case with a tendency for preferred energy transfers from the eddies to the mean flow using the finer resolution eddy kinetic energy nearly doubles at the surface of the subtropical gyre and increases by factors of 3 4 over the jet region and in higher latitudes the spatial characteristics of the mesoscale fluctuations are examined by calculating zonal wavenumber spectra and velocity autocorrelation functions with the higher resolution the dominant eddy scale remains approximately the same in the subtropical gyre but decreases by a factor of 2 in the subpolar areas the wavenumber spectra indicate a strong influence of the model friction in the coarse grid case especially in higher latitudes using the coarse grid there is almost no separation between the energetic eddy scale and the scale where friction begins to dominate leading to steep spectra beyond the cutoff wavenumber using the finer resolution an inertial subrange with a k 3 power law begins to emerge in all model regions outside the equatorial belt despite the large increase of eddy intensity in the fine grid model effects on the mean northward transport of heat are negligible strong eddy fluxes of heat across the midlatitude jet are almost exactly compensated by changes of the heat transport due to the mean flow

indian ocean response to anomalous conditions in 2006 1 the equatorial indian ocean eio exhibited anomalous conditions characteristic of an indian ocean dipole iod during 2006 the eastern eio had cold sea surface temperature anomalies ssta lower sea level shallow thermocline and higher chlorophyll than normal the anomalies in the east restricted to the south of the equator were highest off sumatra the western pole of the iod was marked by warm ssta and deeper thermocline with maxima on either side of the equator an ocean general circulation model of the indian ocean forced by quikscat winds reproduces the iod of 2006 remarkably well the switch over to cooling in the east and warming in the west happened during may and july respectively in the east airsea heat flux initiated cold ssta in the model which were sustained later by oceanic processes in the west surface heat fluxes and horizontal advection caused warm ssta and contribution by the latter decreased after august citation vinayachandran p n j kurian and c p neema 2007 indian ocean response to anomalous conditions in 2006 geophys res lett 34 l15602 doi 10 1029 2007gl030194

spatial variability and hydrologic evolution of australian lake basins analogue for pleistocene hydrologic change and evaporite formation abstract processes evident in basins across hydrologic gradients from humid to arid regions today provide analogues for systems that may have operated in some individual basins during periods of past hydrologic change thus lakes in humid regions today with low salinity sedimentary facies and with morphology controlled largely by wave action may closely resemble past lacustral pluvial phases experienced in zones which today are relatively arid and saline conversely playas controlled today by groundwater and in some cases subject to defletion may resemble those arid and dune building stages experienced by basins in sub humid regions today as they underwent glacial age desiccation in any such sequence of spatial or temporal gradients from humid to more arid conditions the frequency of basin filling and drying modulates the rate of evaporitive loss of interstitial waters from the exposed basin surface this in turn controls the salinity evolution of the interstitial and local groundwaters the notion of closed systems for terminal lakes while satisfactory for analysis of surface water budgets is quite inapplicable to the evolution of brines where surfacewater groundwater exchange during the high salinity drying stages becomes a controlling factor affecting all salt budgets in these systems evaporites may only be preserved when the sub surface waters have evolved to salinites near saturation for the salts concerned if sub surface waters are frequently diluted by surfacewater groundwater exchange evaporites will not be preserved in the record even though the surface system appears hydrologically closed the process of interstitial water evolution which controls efflorescence deflation and salt weathering exerts a dominating influence on basin geomorphic expression as well as on hydrochemical fractionation

giant polygons in the triassic salt of cheshire england a thermal contraction model for their origin abstract the triassic salt in cheshire england has large polygonal patterns on bedding surfaces the polygons are bounded by deep v shaped fissures the fissures have a banded internal structure made up of individual units of pure secondary salt and clastic rich halite the salt was deposited from shallow brines in an arid environment a thermal contraction model is proposed here for the formation of the polygons calculations of the depth of penetration of thermal waves and the net contraction of salt beds indicate that annual temperature fluctuations would produce fissures of the observed depth and width it is suggested that thermal contraction is the most important factor in the initiation of all polygonal patterns on salt surfaces and that the polygon form that eventually develops is de endent on the thickness of the salt bed and the availability of brines to the salt surface

the bowing potential of granitic rocks rock fabrics thermal properties and residual strain the bowing of natural stone panels is especially known for marble slabs the bowing of granite is mainly known from tombstones in subtropical humid climate field inspections in combination with laboratory investigations with respect to the thermal expansion and the bowing potential was performed on two different granitoids cezlak granodiorite and flossenburg granite which differ in the composition and rock fabrics in addition to describe and explain the effect of bowing of granitoid facade panels neutron time of flight diffraction was applied to determine residual macro and microstrain the measurements were combined with investigations of the crystallographic preferred orientation of quartz and biotite both samples show a significant bowing as a function of panel thickness and destination temperature in comparison to marbles the effect of bowing is more pronounced in granitoids at temperatures of 120 c the bowing as well as the thermal expansion of the cezlak sample is also anisotropic with respect to the rock fabrics a quantitative estimate was performed based on the observed textures the effect of the locked in stresses may also have a control on the bowing together with the thermal stresses related to the different volume expansion of the rock forming minerals

the mediterranean messinian salinity crisis an apennine foredeep perspective abstract owing to its expanded stratigraphic sections the apennine thrust belt offers the opportunity to better understand the evaporitic and post evaporitic messinian events a physical stratigraphic framework of messinian deposits based on facies analysis and basin wide correlation of key surfaces and sedimentary cycles is presented it is shown that the messinian apennine foredeep had marginal basins with shallow water primary evaporites and deeper basins where resedimented evaporites accumulated under relatively deep water conditions like many other mediterranean examples primary shallow water evaporites of apenninic marginal basins show evidence for subaerial exposure and erosion however the development of such an erosional surface does not correspond to the deposition of primary evaporites in the deepest part of the basin s here the unconformity can be traced towards the base of resedimented evaporites or to a level within them implying that the deeper basins of the apennine foredeep never underwent desiccation during the messinian salinity crisis but rather received the eroded marginal evaporites this fact usually overlooked raises important questions about the deep desiccation model of the mediterranean

the development and application of the alteration strength index equation abstract we have developed an alteration strength index asi equation to address the effect of hydrothermal alteration on mechanical rock properties this equation can be used to estimate a range of rock strengths comparable to uniaxial compressive strength ucs based on rapid analysis of mineralogy and microstructure we used rock samples from three geothermal fields in the taupo volcanic zone tvz to represent a range of alteration types these are sedimentary intrusive and extrusive rocks typical of geothermal systems from shallow and deep boreholes 72 measured depth md to 3280 md the parameters used in asi were selected based on literature relating these aspects of mineralogy and microstructure to rock strength the parameters in asi define the geological characteristics of the rock such as proportions of primary and secondary mineralogy individual mineral hardness porosity and fracture number we calibrated the asi against measured ucs for our samples from the tvz to produce a strong correlation r2 of 0 86 and from this correlation we were able to derive an equation to convert asi to ucs because the asi ucs relationship is based on an empirical fit the ucs value that is obtained from conversion of the asi includes an error of 7 mpa for the 50th percentile and 25 mpa for the 90th percentile with a mean error of 11 mpa a sensitivity analysis showed that the mineralogy parameter is the dominant characteristic in this equation and the asi equation using only mineralogy can be used to provide an estimated ucs range although the error or uncertainty becomes greater this provides the ability to estimate strength even when either fracture or porosity information are not available for example in the case of logging drill cuttings this research has also allowed us to provide ranges of rock strengths based solely on the alteration zones mineralogy and depth of lithologies found in a typical geothermal field that can be used to update conceptual models of geothermal fields

a model to estimate the depositional brine depths of ancient halite rocks implications for ancient subaqueous evaporite depositional environments a model is derived which allows a more general approach to the interpretation of bromine profiles in halite rocks than is possible with the models of kuhn or holser allowing for an open system with influx and reflux reduces the depth of brine necessary to generate a given salt deposit even very small and regular bromine gradients which historically have been interpreted as the result of deposition from deep brine bodies can be generated in an open system from brine no more than a few tens of metres deep the bromine gradient produced from a given depth of brine is strongly dependent on the composition and amount of influx but less so on the composition of brine already in the basin a zechstein profile is analysed which in a closed basin would require brine 2665 m deep it can equally be modelled by influx of normal seawater which fully replenishes a basin no more than 140 m deep a somewhat irregular profile from the paradox basin instead of requiring a basin 100 400 m deep can be modelled as being produced by deposition from brines only 10 m deep reflux in both cases can only be a few per cent of influx at a maximum

late quaternary spatio temporal limnological variations in the altiplano of bolivia and peru abstract between the western and eastern andean cordilleras in peru and bolivia there are three main lacustrine basins lake titicaca lake poopo and the group of coipasa uyuni for the past few millennia highly variable environmental conditions have been recorded in their sediments today a latitudinal meteorological gradient influences the lakes status leading to specific deposits and ostracod communities lake titicaca in the north is oligohaline whereas lake poopo further south is polyhaline in the south the coipasa uyuni depression is characterized by a 12 000 km2 surficial salt crust during the late pleistocene ca 40 000 to 25 000 yr b p the water depth and salinity in paleolake poopo fluctuated widely and paleolake titicaca was slightly larger than at present sedimentation was mostly biocarbonate in the shallower areas and it was detrital organic in the deepest zones during the holocene a dry period transformed lake poopo into a salar with evaporite precipitation lake titicaca registered a large decline in water level 8100 3600 yr b p initially inducing gypsum precipitation followed by short influxes of water with an ostracod faunal composition similar to that of the modern brines of lake poopo lake titicacas present condition only appeared between 2200 and 1500 yr b p

does strong tropospheric forcing cause large amplitude mesospheric gravity waves a deepwave case study the deepwave deep propagating wave experiment campaign was designed for an airborne and ground based exploration of gravity waves from their tropospheric sources up to their dissipation at high altitudes it was performed in and around new zealand from 24 may till 27 july 2014 being the first comprehensive field campaign of this kind a variety of airborne instruments was deployed onboard the research aircraft nsf ncar gulfstream v gv and the dlr falcon additionally ground based measurements were conducted at different sites across the southern island of new zealand including the dlr rayleigh lidar located at lauder 45 04 s 169 68 e we focus on the intensive observing period iop 10 on the 4 july 2014 when strong wsw winds of about 40 m s at 700 hpa provided intense forcing conditions for mountain waves at tropopause level the horizontal wind exceeded 50 m s and favored the vertical propagation of gravity waves into the stratosphere the dlr rayleigh lidar measured temperature fluctuations with peak to peak amplitudes of about 20 k in the mesosphere 60 km to 80 km msl over a period of more than 10 hours two research flights were conducted by the dlr falcon falcon flight 04 and 05 during this period with straight transects mt aspiring 2a over new zealand s alps at three different flight levels around the tropopause approx 11 km msl these research flights were coordinated with the gv research flight 16 where the largest mountain wave amplitudes at flight level approx 13 km msl were measured during deepwave additionally a first analysis of falcon s in situ flight level data revealed amplitudes in the vertical wind larger than 4 m s at all altitudes in the vicinity of the highest peaks of the southern alps here we present a comprehensive picture of the gravity wave characteristics and propagation properties during this interesting gravity wave event we use the airborne observations combined with a comprehensive set of ground based measurements consisting of 13 radiosoundings 1 5 hourly interval together with the dlr rayleigh lidar to cover the altitude range from the troposphere to the mesosphere high resolution 1 hourly ecmwf analyses and forecasts are used to estimate the propagation conditions of the excited mountain waves the goal of our investigation is to find out whether the large amplitude mesospheric gravity waves are caused by the strong tropospheric forcing

salt bursting tests on volcanic tuff rocks from mexico during the pre colonial period all the architectural constructions of the maya and the later aztec culture were made from different types of rocks available in the nearby surroundings of the settlements later the architecture characterizing the spanish colonization utilized volcanic tuff rocks for ashlars and masonry facades volcanic tuffs were used in large quantities and are still the main natural building rock used in most of the country tuffs are mostly soft and porous rocks that can be easily cut and reworked they are however very susceptible to the effects of weathering especially the deterioration caused by salt crystallization seventeen volcanic tuff samples from mexico used as natural building stones were studied these tuffs show highly variable compositions and different porosities and textural properties as well as very different behaviors in regard to salt crystallization the petrographic petrophysical mineralogical and geochemical properties of the 17 samples were analyzed before and after a large number of salt bursting tests in order to try and determine the main factors leading to the weathering caused by salt crystallization some factors appear to have a real importance in regard to the resistance against salt crystallization two of the most important are the water vapor diffusion value and the pore radii distribution however microporosity also becomes a relevant factor for rapid salt destruction if it reaches more than 50 of the pore volume all these effects related to the salt crystallization are dependent on the presence of water in any form so the climatic conditions must also play a principal role

differences in the quality of polishing between sound and weathered granites aesthetic characteristics are important when rocks are used as construction materials among all the surface finishes available the polished finish is the one which best enhances the rock attractiveness colour c roughness r and gloss g are surface properties usually used to assess the rock polishing in this research the crg properties were assessed in polished samples of three ornamental granites with different textures and physical mechanical properties one weathered and two sound c was evaluated in cie l a b and cie l c abhab systems r with ra and rz parameters and g using the 20 60 and 85 geometries the weathered granite presents a noticeable colour variation especially in the b parameter while the sound ones have a more homogeneous colour sound and more textural homogeneous granites have a low surface roughness and high gloss which are uniformly distributed the weathered granite shows a higher surface roughness and lower gloss with scattered distribution the mineral contacts are the main cause of the surface irregularities the results show the interdependence between the crg properties and stress the importance of the polishing process for enhancing the aesthetic characteristics of the granites crg properties could be used for quality control in granite processing plants thus avoiding noticeable differences in the facades of buildings particularly when weathered granites are used

discontinuity modelling and rock block geometry identification to optimize production in dimension stone quarries abstract evaluating the reserves of commercial blocks in dimension stone quarries requires determining in situ block geometry furthermore to extract blocks the planes need to be cut and the intersection between the fracture network and the cutting patterns forms smaller blocks the optimization of the cutting patterns can increase quarrying efficiency resulting in less environmental damage in this paper a numerical algorithm was selected from various algorithms and was developed for in situ block identification the optimization approach was adopted to increase quarry productivity and to investigate quarrying direction on a large scale however on a small scale this approach was employed for checking the distance between the cutting planes according to the algorithms developed 3d quarryoptimizer was programmed in the matlab environment to determine the geometry of the blocks and to optimize extraction based on the quality classification of the blocks formed the algorithms developed have such advantages as the optimization approach and taking the geometry of the blocks into consideration this methodology was applied in a marble quarry and a granite quarry research conducted in the granite quarry showed that the program is a practical tool to determine the geometry of in situ blocks and their quality classification the marble quarry was studied for the optimization phase the large scale optimization indicated a maximum difference of 17 in the yield among several quarrying directions on a small scale however a 120 increase in quarry yield was achieved with the optimal interval between the cutting planes

estimation of uniaxial compressive strength of rock materials by index tests using regression analysis and fuzzy inference system abstract this paper presents a comparative evaluation of efficacies of different index tests and analysis techniques i e regression analyses and fuzzy inference system in predicting uniaxial compressive strength ucs of granite schist and sandstone ucs and indices such as block punch index point load strength schmidt rebound hardness ultrasonic p wave velocity and physical properties effective porosity and density were determined for the concerned rocks from simple regression analyses it was apparent that for granite and sandstone performances of all six indices are reasonably good in predicting ucs in case of granite block punch index and point load strength are the best indices whereas effective porosity point load strength and schmidt rebound hardness are the most efficient indices for sandstone in case of schist however ultrasonic p wave velocity does not seem to be a competent index unlike other indices where point load strength proves to be the best one from the critical analysis of the tests results it was demonstrated and subsequently concluded that index test results of different rock types with different geology should not be clubbed together for statistical correlation with any rock mechanical parameter like ucs both multiple regression analyses and the fuzzy inference system exhibited better predictive performances for ucs than simple regression analyses in addition to the coefficient of correlation the variance account for vaf and the root mean square error rmse were also calculated to check the predictive performances of these two models and it was found that the predictive performances of both models are comparable however one should be cautious while employing multiple regression analysis in predicting ucs as there is always a chance of cumulating plausible errors that might have remained within individual index test results on the other hand fuzzy inference system seems to be an efficient tool in predicting ucs of rock materials from indices because of its efficacy in handling uncertainties in the test results with transparency

dynamics of wind forced intraseasonal zonal current variations in the equatorial indian ocean 1 this study examines the structure and dynamics of wind forced intraseasonal zonal current variability in the equatorial indian ocean we take advantage of a variety of satellite and in situ data sets including unprecedented 4 8 year long velocity time series records from the research moored array for african asian australian monsoon analysis and prediction rama program spectral analysis reveals prominent intraseasonal zonal currents variations along the equator with periods of 30 70 days these oscillations are vertically in phase above the thermocline and propagate eastward with the local zonal winds in the thermocline intraseasonal zonal velocity variations also propagate eastward across a broad range of phase speeds expected for low baroclinic equatorial kelvin waves amplitudes decrease with depth with deeper levels leading those near surface collectively these results suggest that the near surface layer responds directly to intraseasonal zonal wind stress forcing and that subsequently energy radiates downward and eastward in the thermocline in the form of wind forced equatorial kelvin waves in addition intraseasonal zonal current variability on the equator is coherent with off equatorial sea surface height fluctuations in the eastern and central of the basin this coherence is primarily due to the fact that equatorial zonal wind variations are associated with off equatorial wind stress curls that can generate local ekman pumping and westward propagating rossby waves

intraseasonal variability of sea surface height in the bay of bengal intraseasonal variability isv of sea surface height ssh over the bay of bengal bob is studied using altimetry data and an eddy resolving ocean model in both the model hindcast and satellite observations large ssh isv is found along the eastern and northern coasts of the bob in the western bob and in a zonal band across the bay centered near 5 degrees n the isv displays a clear seasonality in the western bob it reaches its annual maximum in spring whereas it does so in summer and autumn southeast of sri lanka driven by equatorial intraseasonal winds equatorial kelvin waves propagate eastward reach the western coast of sumatra and reflect there to propagate around the perimeter of the bob as coastally trapped waves two distinct bands of high eddy activity are detected in the western and central bob respectively in both bands isolated eddies propagate southwestward eddy formation in the eddy train in the central bay is linked to the coastal wave as it bends around the corner of the irrawaddy delta off myanmar eddy activity contributes to the high isv in the central bay to some extent an energetics analysis indicates that high total eddy energy in the western bob is due to barotropic baroclinic instability of the mean current citation cheng x s p xie j p mccreary y qi and y du 2013 intraseasonal variability of sea surface height in the bay of bengal j geophys res oceans 118 816 830 doi 10 1002 jgrc 20075

salinities and sediment transport in the bolivian highlands guyot j l roche m a noriega l calle h and quintanilla j 1990 salinities and sediment transport in the bolivian highlands j hydrol 113 147 162 salinities and sediment loads of the rivers of the entire interior drainage basin of the lake titicaca rio desaguadero lake poopo and salars as well as their evolution from upstream to downstream have been characterized on the basis of the results of four samplings during runoff periods on the other hand the regimes of dissolved and suspended matter transport are characterized with perioclic measurements and samplings at hydrometrical stations over several years the junction of lake poopo and the salar of coipasa since 1985 is noted which recalls that an unique terminal lake of large area existed during some parts of the quaternary mechanical and chemical erosion rates have been calculated for the basins that drain the western rio mauri and eastern rio suches cordilleras of the bolivian andes most of the sediment comes from the western cordillera with a mechanical erosion rate of 640 t kmz yr i for the basin of the rio mauri on the other hand lake titicaca is the main source of dissolvea matter to lake poopo via the rio desaguadero

elastic anisotropy and pore space geometry of schlieren granite direct 3 d measurements at high confining pressure combined with microfabric analysis pore space geometry of granitic rocks and its evolution with depth are key factors in large scale seismics or in projects of enhanced geothermal systems or of deep hazardous waste repositories in this study we studied macroscopically anisotropic schlieren bearing granite by experimental p wave velocity v p measurements on spherical sample in 132 directions at seven different confining pressures in the range 0 1 400 mpa in order to discriminate the phenomena affecting the rock elastic properties we analysed the orientation of microcracks and of grain boundaries and we measured the anisotropy of magnetic susceptibility of the rock three sets of microcracks were defined with two of them linked to the massif exfoliation process and one to cooling contraction of the massif during pressurization the measured mean v p and v p anisotropy degree at ambient pressure and at highest confinement 400 mpa yielded 3 3 km s 1 and 24 per cent and 6 2 km s 1 and 3 per cent respectively the associated v p anisotropy pattern was transversely isotropic and governed by the schlieren with a minimum v p direction perpendicular to them and a girdle of high v p directions parallel to them the highest change in v p was observed between 0 1 and 10 mpa suggesting a significant closure of porosity below depths of 500 m change of the v p anisotropy pattern to orthorhombic together with increase of mean v p and v p anisotropy degree during depressurization was attributed to inelastic response of one of the sets of microcracks to the loading unloading cycle

dynamics of andaman sea circulation and its role in connecting the equatorial indian ocean to the bay of bengal circulation in the bay of bengal bob is driven not only by local winds but are also strongly forced by the reflection of equatorial kelvin waves ekws from the eastern boundary of the indian ocean the equatorial influence attains its peak during the monsoon transition period when strong eastward currents force the strong ekws along the equator the andaman sea lying between the andaman and nicobar island chains to its west and indonesia thailand and myanmar to the south east and north is connected to the equatorial ocean and the bob by three primary passages the southern 6 n middle 10 n and northern 15 n channels we use ocean circulation models together with satellite altimeter data to study the pathways by which equatorial signals pass through the andaman sea to the bob and associated dynamical interactions in the process the mean coastal circulation within the andaman sea and around the islands is primarily driven by equatorial forcing with the local winds forcing a weak sea level signal on the other hand the current forced by local winds is comparable to that forced remotely from the equator our results suggest that the andaman and nicobar islands not only influence the circulation within the andaman sea but also significantly alter the circulation in the interior bay and along the east coast of india implying that they need to be represented accurately in numerical models of the indian ocean

empirical ratio of dynamic to static stiffness for propped artificial fractures under variable normal stress abstract the stiffness coefficient is a key parameter of rock fractures that controls the properties and behavior of a rock mass according to the displacement discontinuity theory the dynamic stiffness of rock fractures can be back analyzed using stress wave propagation this study aims to measure the dynamic stiffness of rock fractures then develop an empirical ratio to describe the relationship between dynamic and static stiffness propped artificially fractured shale and granitic rock samples are employed mechanical and ultrasonic tests are conducted on two artificial rock fractures during uniaxial loading and unloading as normal stress changes from 1 mpa to 50 mpa the average dynamic normal stiffness of shale and granitic rock fractures changes from 330 gpa m to 1960 gpa m and from 90 gpa m to 2320 gpa m respectively for both artificial fractures the dynamic stiffness is higher than the static stiffness but approaches the static stiffness with increasing normal stress the ratio of dynamic to static normal stiffness is approximately 2 0 at a normal stress of 15 mpa this ratio approaches 1 0 with increasing normal stress and varies widely under low normal stress this study provides a method for evaluating the static or dynamic stiffness of rock fractures which has important applications for seismic surveys or acoustic logs in the field of geological engineering

a numerical model of the circulation in knight inlet british columbia canada abstract during spring 1988 a period of low freshwater runoff and summer 1989 a period of high freshwater runoff month long observations of velocity temperature and salinity were made throughout the water column in knight inlet both up inlet and down inlet of the sill measurements were made at depths of 2 4 6 9 and 12 m using s4 current meters at depths down to about 200 m using profiling current meters and at depths deeper than 200 m using aanderaa current meters anemometers were deployed at two locations along the inlet a laterally integrated two dimensional numerical model of the inlet that uses the mellor and yamada level 2 5 turbulence closure scheme and that accounts for the combined influence of the winds tides and freshwater runoff has been used to produce 30 day simulations of the velocity and density field in the inlet the vertical coordinate is transformed in the model so that very fine vertical resolution can be attained near the surface even though the tidal range is larg

thermal stress induced microcracking in building granite abstract microcracking induced by wide fluctuations in temperature affects granite quality and durability making the stone more vulnerable to decay determining the extent of that effect is not always straightforward however given the excellent durability of these materials four types of construction granite quarried in the region of madrid spain and frequently used in both the built heritage and in de novo construction alpedrete cadalso de los vidrios colmenar viejo and zarzalejo were exposed to 42 thermal cycles 105 20 c une en 14066 2003 petrographic and petrophysical properties were analysed using both destructive and non destructive techniques microcracking generated in the granite stones by 42 thermal cycles had barely any impact on their petrophysical properties which are the parameters normally assessed to establish material quality and durability their petrographic properties which are not generally assessed in this type of studies were affected however this study contends that petrographic analysis is needed to objectively quantify the actual quality and durability of the most highly resistant materials when petrophysical studies are inconclusive petrographic and fluorescence microscopy along with fractography are among the most prominent techniques for petrographic exploration thanks to the deployment of these techniques mineral microcracking could be monitored throughout the present tests conducted the microscopic findings revealed substantial micro textural and microstructural change in and around the granite minerals which play a prominent role in decay the findings showed that pre existing microcracks coalesced and generated further microcracking as decay progressed microcracking was most intense in zarzalejo granite due to its textural characteristics determined by its high feldspar content microscopic observation revealed that the microstructure of feldspar minerals with their crystallographic anisotropies and secondary mineral phases favoured microcrack development zarzalejo granite exhibited lower quality and durability than colmenar viejo and cadalso de los vidrios granites which were more resistant to heat treatment

bedforms in salt deposits of the dead sea brines abstract study of salt deposits emphasizes the mineralogical and geochemical aspects of origin with but little attention to processes and features of physical sedimentation deposition from saturated brines along one of the main conveyance canals of the dead sea works near sedom southern israel indicates however that in open channel flow the halite sediment develops bedforms identical to those reported in alluvial channel deposits the conveyance canal is trapezoidal with side slopes of 1 2 bottom width of 17 m bankfull depth of 1 5 m and a gradient of 0 00022 design manning s n is 0 0223 decreasing to about 0 020 after deposition of the fine halite lining under normal operating conditions flow velocity is about 30 cm s and depth is about 1 m the conveyed brine with a densi y of 1 29 and viscosity of 5 cp is supersaturated with respect to halite and deposition of halite occurs aided by temperature fluctuations mixing and natural and pump induced turbulence the sediment consists of halite with minor amounts of carnallite and it is very poorly sorted a conventional interpretation of the grain size distribution is not applicable however since the finer fractions up to about 100 microns consist of single cube block or prism shaped crystals whereas the coarser material includes mainly porous and irregular clusters of crystals and larger ball like aggregates up to about 3 mm in diameter bedforms encountered along the canal include current crescents and shadows due to deformation of flow around obstacles such as bottom irregularities and salt l mps transverse linguoidal and catenary ripples and megaripples some of which may easily be mistaken for karrenlike products of solution mass transfer and for features of syneresis and longitudinal ridge patterns due to three dimensional systems of streamwise vortices the comparison of results of stokesian settling hindered settling and pipe flow of brines and of suspensions with different concentrations of solids indicates similar hydraulic behavior of salt brine and quartz water systems after adjustment for particle and fluid properties the observed bedforms fall into the same hydraulic factor fields as determined for bedforms in alluvial channels salt deposits therefore clearly belong to the wide group of chemical precipitates ranging from igneous rocks to industri l slurry deposits which record the process of mechanical transport and deposition

yanai waves in the western equatorial indian ocean 1 observations and models have shown the presence of intraseasonal fluctuations in 20 30 day and 10 20 day bands in the equatorial indian ocean west of 60 e weio their spatial and temporal structures characterize them as yanai waves which we label low frequency lfyw and high frequency hfyw yanai waves respectively we explore the dynamics of these intraseasonal signals using an ocean general circulation model modular ocean model and a linear continuously stratified model yanai waves are forced by the meridional wind y everywhere in the weio most strongly during the monsoon seasons they are forced both directly in the interior ocean and by reflection of the interior response from the western boundary interference between the interior and boundary responses results in a complex surface pattern that propagates eastward and has nodes yanai waves are also forced by instabilities primarily during june july in a region offshore from the western boundary 52 55 e at that time eddies generated by barotropic instability of the southern gyre are advected southward to the equator there they generate a westward propagating cross equatorial flow field veq with a wave number frequency spectrum that fits the dispersion relation of a number of yanai waves and these waves are efficiently excited typically yanai waves associated with several baroclinic modes are excited by both wind and eddy forcing and typically they superpose to create beams that carry energy vertically and eastward along ray paths the same processes generate lfyws and hfyws and hence their responses are similar differences are traceable to the property that hfyws have longer wavelengths than lfyws for each baroclinic mode

alternate interpretation of the messinian salinity crisis controversy resolved a high resolution chronology of the mediterranean messinian salinity crisis is proposed two types of evaporite deposition may be distinguished those in marginal areas vs those in basinal ones their diachroneity is deduced from the stratigraphic relationships linking these evaporites to a major messinian erosional surface a two step model is proposed for the evolution of the salinity crisis through time during the first phase from 5 75 to 5 60 ma the deposition of marginal evaporites took place in response to a modest sea level fall in the second interval from 5 60 to 5 32 ma the mediterranean basin became isolated during this later period the deposition of basinal evaporites and the cutting of the mediterranean canyons took place

observational evidence of lower frequency yanai waves in the central equatorial indian ocean the analysis of long time series current meter data from a mooring at 77 0 e and equator during 20032007 along with mean sea level anomaly msla data throws light on the occurrence of the lower frequency yanai wave 24 40 day in the upper water column of the central equatorial indian ocean eio during the positive indian ocean dipole iod years of 2003 2004 2006 and 2007 and its absence during the negative iod year of 2005 this result is in contrast with the earlier studies that observed only the higher frequency biweekly period yanai wave in this region we propose a new notion for the generation of the lower frequency yanai wave in the upper central eio due to the positive iod phenomenon the strong meridional current shear created by the northward shifting and strengthening of the westward flowing south equatorial current sec associated with positive iod and the eastward flowing southwest monsoon current provides energy for the generation of lower frequency yanai waves the vertical stratification of the water column appears to be responsible for the trapping of different frequency of yanai wave with only the higher frequency yanai wave in the region of lower pycnocline during positive iod the strongly stratified upper water column responds to the lower frequency yanai wave while the deeper ocean 4000m exhibited longer period 47 day oscillation the expected surface signature of madden julian oscillation mjo seems to be suppressed by strong easterlies during the positive iod years

numerical simulation of the observed near surface east india coastal current on the continental slope we simulate the east india coastal current eicc using two numerical models resolution 0 1 circ times 0 1 circ an oceanic general circulation model ogcm called modular ocean model and a simpler linear continuously stratified lcs model and compare the simulated current with observations from moorings equipped with acoustic doppler current profilers deployed on the continental slope in the western bay of bengal bob we also carry out numerical experiments to analyse the processes both models simulate well the annual cycle of the eicc but the performance degrades for the intra annual and intraseasonal components in a model resolution experiment both models run at a coarser resolution of 0 25 circ times 0 25 circ simulate well the currents in the equatorial indian ocean eio but the performance of the high resolution lcs model as well as the coarse resolution ogcm which is good in the eicc regime degrades in the eastern and northern bob an experiment on forcing mechanisms shows that the annual eicc is largely forced by the local alongshore winds in the western bob and remote forcing due to ekman pumping over the bob but forcing from the eio has a strong impact on the intra annual eicc at intraseasonal periods local equatorial forcing dominates in the south north because the kelvin wave propagates equatorward in the western bob a stratification experiment with the lcs model shows that changing the background stratification from eio to bob leads to a stronger surface eicc owing to strong coupling of higher order vertical modes with wind forcing for the bob profiles these high order modes which lead to energy propagating down into the ocean in the form of beams are important only for the current and do not contribute significantly to the sea level

tropical climate changes at millennial and orbital timescales on the bolivian altiplano tropical south america is one of the three main centres of the global zonal overturning circulation of the equatorial atmosphere generally termed the walker circulation1 although this area plays a key role in global climate cycles little is known about south american climate history here we describe sediment cores and down hole logging results of deep drilling in the salar de uyuni on the bolivian altiplano located in the tropical andes we demonstrate that during the past 50 000 years the altiplano underwent important changes in effective moisture at both orbital 20 000 year and millennial timescales long duration wet periods such as the last glacial maximum marked in the drill core by continuous deposition of lacustrine sediments appear to have occurred in phase with summer insolation maxima produced by the earth s precessional cycle short duration millennial events correlate well with north atlantic cold events including heinrich events 1 and 2 as well as the younger dryas episode at both millennial and orbital timescales cold sea surface temperatures in the high latitude north atlantic were coeval with wet conditions in tropical south america suggesting a common forcing

characterisation of monzogranitic batholiths as a supply source for heritage construction in the northwest of madrid abstract the church of the assumption of our lady in valdemorillo madrid spain is almost entirely built with granitoids the studies and analyses were focused on the oldest part of the building ghosts corner which will be restored and rehabilitated in the near future homogeneous monzogranite is the predominant granitoid used in the ghosts corner followed by granitic porphyry porphyrytic monzogranite gneiss and leucogranite the original quarries that supplied homogeneous monzogranites for the first construction stages correspond to blocks present in the monument s surroundings quarries that supplied the granitic porphyries correspond to the dykes located to east southeast of valdemorillo which are oriented n s in relation to their intrusion direction the combined use of ultrasonic velocity and schmidt hammer techniques allowed first selection of the most representative blocks and ashlars for sampling this reduced sampling to a minimum but yielded representative results for the whole building second the combined values were used to compare results for the building stones of the church to rocks from the surrounding quarries stones from the building showed lower ultrasonic and schmidt hammer values and higher porosity and water saturation values compared to the original quarry rocks the anisotropy indices are directly related to the decay processes in the stone spalling of homogeneous monzogranite and grain disintegration in granitic porphyries finally the methods applied are inexpensive easy to use and non destructive techniques very advisable properties when working with built heritage

bowing of dimensional granitic stones bowing is a well known phenomenon seen in marbles used as building veneers this form of rock weathering occurs as a result of external factors such as temperature humidity the system for anchoring the marble slabs or the panel dimensions under the same external conditions many factors will determine the degree of deformation including petrography thermal properties and residual locked stresses the usual way to solve the problem of bowed marble slabs is to replace them with other materials such as granites in which the deformation still exists but is less common in this study eight ornamental granites with different mineralogy grain size grain shape porosity and fabric were tested in a laboratory to assess their susceptibility to bowing three slabs of granite each cut with a different orientation were studied under different conditions of temperature 90 and 120 c and water saturation dry and wet to investigate the influence of these factors together with that of anisotropy at 90 c only the granite with the coarsest grain size and low porosity exhibited deformation under wet conditions at 120 c and wet conditions three of the granites showed evident signs of bowing again the granite with the coarsest grain size was the most deformed it was concluded that the wide grain size distribution influences microcracking more than other expected factors such as the quartz content of the rock also mineral shape preferred orientation and porosity play an important role in the bowing of the studied granites

origin of intraseasonal variability of circulation in the tropical central indian ocean observed upper ocean currents south of sri lanka exhibit large irregular fluctuations with periods of days to weeks an ocean model driven by daily surface winds is able to reproduce the observed fluctuations we find from model experiments that low frequency 30 50 day intraseasonal variability isv arises when rossby waves radiated from the eastern boundary are amplified by hydrodynamic instability in the eastern and central indian ocean high frequency 10 15 day isv is forced directly by isv of the wind field in the eastern indian ocean in spite of the contribution from instability the ocean circulation south of sri lanka is a deterministic response to wind forcing

halite depositional facies in a solar salt pond a key to interpreting physical energy and water depth in ancient deposits subaqueous deposits of aragonite gypsum and halite are accumulating in shallow solar salt ponds constructed in the pekelmeer a sea level salina on bonaire netherlands antilles several halite facies are deposited in the crystallizer ponds in response to difference in water depth and wave energy cumulate halite which originates as floating rafts is present only along the protected upwind margins of ponds where low energy conditions foster their formation and preservation cornet crystals with peculiar mushroom and mortarboard shaped caps precipitate in centimetre deep brine sheets within a couple of metres of the upwind or low energy margins downwind from these margins cornet and chevron halite precipitate on the pond floors in water depths ranging from a few centimetres to approximately 60 cm halite pisoids with radial concentric structure are precipitated in the swash zone along downwind high energy shorelines where they form pebbly beaches this study suggests that primary halite facies are energy and or depth dependent and that some primary features if preserved in ancient halite deposits can be used to infer physical energy conditions subenvironments such as low to high energy shorelines and extremely shallow water depths in ancient evaporite basins

a geological numerical model for paleozoic global evaporite deposition a geologically driven model for evaporative deposition of marine sulfate and other sulfur fluxes roughly reproduces the observed stratigraphic record of paleozoic global evaporite depositional rates and the observed delta 34 s age curve erosional and depositional fluxes in this model are controlled by areas available for erosion and deposition which are in turn controlled by sea level global hypsography and plate tectonic movement of the continents through low latitude evaporite belts sea level also provides the record of seafloor spreading rates needed to determine fluxes at mid ocean ridges the success of this geologically driven model as opposed to geochemical models dependent on isotopic compositions or reservoir contents to determine fluxes suggests the possibility of modeling fluxes of elements that have no useful isotopic record it also suggests that variability of the stratigraphic record of evaporite deposition is not entirely the result of accidents of erosion and preservation bu

signature of la nina in interannual variations of the east india coastal current during spring we have investigated interannual variations of the spring february april average east india coastal current eicc magnitude between 2000 and 2018 using oscar ocean surface current analysis real time current and a linear continuously stratified lcs model interannual variability of the eicc shows significant decrease in magnitude during spring of 2000 2008 and 2011 the years when high negative oni oceanic nino index for sea surface temperature value has been observed due to dominance of strong la nina events our lcs model also successfully simulates these interannual variability of the spring average eicc between 2000 and 2018 we carried out numerical experiments using lcs model related to local and remote forcing response on eicc dynamics of the eicc during spring are dominated by four different forcing processes local wind along east coast of india remote forcing response from the eastern and northern boundary of the bob including islands interior bob and the equatorial indian ocean eio during el nino and normal spring years strong poleward interannual eicc are due to very weak negligible order of 0 5 cm s 1 eicc from eio remote response and in phase poleward eicc formation using other three forcings however during la nina spring years weak order of 0 10 cm s 1 poleward interannual eicc are formed due to destructive interference between equatorward current order of 10 25 cm s 1 from eio forcing and in phase poleward current from other three forcings we have also found propagation of interannual upwelling downwelling favorable kelvin wave from eio via eastern and western boundary of the bob during spring in the el nino la nina years the interannual variations in the propagation of eio kelvin wave are associated with the changes in the eio zonal wind direction by climate mode like enso el nino southern oscillation

implications of pore space characteristics on diffusive transport in basalts and granites a detailed characterization of the pore space is crucial for understanding of transport and element transfer in rocks here the effect of differences in texture and content of secondary minerals on transport in pore systems was determined for two rocks of widespread occurrence mid ocean ridge basalts morb and granites pore space characteristics were analyzed by hg porosimetry intrusion of a molten alloy and synchrotron based x ray tomographic microscopy for evaluating the role of pore space characteristics for the prediction of diffusive transport data on porosity and the effective diffusion coefficient deff were compared extended connective pore systems due to cracks and mineral dissolution are present in samples of both rocks indicating high internal specific surface area uneven pore size distributions in altered morb samples can be assigned to secondary minerals pore spaces determined by x ray tomography used to determine main direction of pores in the 3 d orthogonal system suggest a slight anisotropy in log log plots both rocks show roughly a linear dependence of deff for h2o and compounds with comparable diffusivities d2o monovalent cations and anions on porosity but at same porosity deff is clearly higher in granitic than in basaltic samples this difference is increasing with decreasing porosity indicating that at low porosities the efficiency of element transport in basaltic samples is diminished mainly inherited by the presence of small pores slowing down diffusion the fact that diffusive transport in basaltic rocks is stronger dependent on porosity than in granitic rocks shows that also other rock characteristics such as pore size distribution and tortuosity of the pore network highly affected by the alteration degree can markedly affect transport and reactivity of pore solution

assessment of rock geomechanical quality by quantitative rock fabric coefficients limitations and possible source of misinterpretations abstract rock microfabrics were quantified by image measurement system petrographic image analysis of thin sections along with common measured parameters grain area and size length of major and minor axes and their orientation some quantitative parameters aspect ratio grain boundary smoothness and fabric coefficients micropetrographic quality index k texture coefficient tc indexes of interlocking t and grain size homogeneity g were determined the reliability of these parameters for the evaluation of geomechanical properties was tested on the set of granitic rocks showing pronounced variability in rock mechanical properties none of the tested rock fabric coefficients or parameters proved a close correlation to rock mechanical properties except grain size based on experimental findings the grain size is along with porosity the controlling factor of rock mechanical properties of genetically and mineralogically similar rocks obliteration of the real effects of rock fabric parameters on the mechanical properties of rocks by application of complex fabric coefficients disables their practical use in petrography applied to geomechanics

sedimentology and development of parabolic dunes grande prairie dune field alberta the grande prairie dune field in northwest central alberta is composed of parabolic and dome dunes presently inactive but which had developed under westerly winds two parabolic dune types are rec