influence of waves and horseshoe crab spawning on beach morphology and sediment grain size characteristics on a sandy estuarine beach the effects of wave action and horseshoe crab spawning on the topography and grain size characteristics on the foreshore of an estuarine sand beach in delaware bay new jersey usa were evaluated using data collected over six consecutive high tides data were gathered inside and outside a 25 m long exclosure constructed to create a control area free of disturbance by crabs the density of crabs in the swash zone outside the exclosure was 8 1 organisms m 2 the maximum depth of sediment activation on the upper foreshore where spawning occurred was 0 103 m during periods characterized by low significant wave heights 0 08 m this depth is greater than the depth of activation by waves alone during moderate significant wave heights of 0 16 0 18 m but less than the maximum depth 0 127 m recorded when spawning occurred during periods of moderate wave heights spawning combined with moderate wave heights creates a concave upper foreshore that is similar to the type of profile change that occurs during storms thus lowering the wave energy threshold for morphological response spawning during low wave heights increases the mean grain size and sorting of surface sediments caused by the addition of gravel to the swash sedimentological differences are most pronounced on the upper foreshore and data from this location may be most useful when using grain size characteristics to interpret the effect of spawning in the sedimentary record depths of sediment reworking by horseshoe crabs can be greater than those by subsequent storm waves so evidence of spawning can be preserved on non eroding beaches greater depth of activation by horseshoe crab spawning than by waves alone even during moderate energy conditions reveals the importance of crab burrowing in releasing eggs to the water column and making them available for shore birds

multiple dating approaches applied to the recent sediments in the yangtze river changjiang subaqueous delta the accumulation rate of recent deposits in a delta environment is critical to the study of delta dynamics and their sustainable management the most commonly used dating approach for recent 100

retrograde methane dominated fluid inclusions from high temperature granulites of rogaland southwestern norway non aqueous inclusions in the high grade 800 1 000c 4kbar metamorphic rogaland region southwestern norway consist of mixtures of co sub 2 ch sub 4 n sub 2 in particular the fluid inclusions in quartz veins in migmatites are characterized by high ch sub 4 concentrations and they were re equilibrated at temperatures below 500c during isobaric cooling observations by microthermometry demonstrated several complicated sequences of phase transitions including partial and metastable homogenization at lower temperature than melting and s l or s v transitions the phase behavior reflects a wide variation in composition and molar volume fluid compositions were measured by raman microspectrometry by this method also small amounts of graphite have been detected in co sub 2 ch sub 4 inclusions the instantaneous formation of graphite in a co sub 2 ch sub 4 inclusion by induction of the argon laser beam has been observed which points to the metastability of the co sub 2 ch sub 4 mixture the calculated densities of the observed fluid mixtures are relatively low necessitating a revision of the earlier interpretation of these inclusions as containing pure high density fluids inclusions in quartz trapped after the peak of metamorphism record fluid heterogeneity which may present evidence for fluid deficient metamorphism during the retrograde m2 m3 metamorphism

the role of bore collapse and local shear stresses on the spatial distribution of sediment load in the uprush of an intermediate state beach abstract spatial variations in sediment load in the swash uprush and textural properties of sediment in transport were evaluated to investigate the mechanisms responsible for sediment transport during wave uprush four streamer traps were deployed at 2 0 m intervals across the swash zone of a sheltered microtidal sandy beach at port beach western australia over a 4 day period during these trapping experiments offshore significant wave heights were 0 3 0 5 m and wave periods were about 10 s the average width of the uprush zone was 6 9 m and the average uprush duration was 5 9 s cross shore distributions of sediment load for 70 uprush events reveal a maximum in sediment load landward of the base of the swash at about 20 of swash width during single events and a maximum closer to mid swash at about 40 of swash width during multiple events characterized by swash interactions settling velocity distributions of trap samples during individual uprush events are similar to distributions found on the beach surface with the lowest settling velocities finest sediments near the base of the swash zone and maximum settling velocities coarsest sediments around the mid swash position it was found that sediment transport during wave uprush occurs through two distinct mechanisms 1 sediment entrainment during bore collapse seaward of the base of the swash zone and subsequent advection of this bore entrained sediment up the beach by wave uprush and 2 in situ sediment entrainment and transport induced by local shear stresses during wave uprush both mechanisms are considered important but the first mechanism is considered most significant during the early stages of wave uprush when sediment is transported mainly in suspension while the second mechanism is likely to dominate the mid to later stages of wave uprush when sediment is transported mainly by sheet flow the relative importance of the two mechanisms will vary between different beaches with the morphodynamic state of the beach reflective versus dissipative expected to play a major role

recalibration of mutually consistent garnet biotite and garnet cordierite geothermometers abstract garnet biotite and garnet cordierite geothermometers have been consistently calibrated using the results of fe 2 mg cation exchange experiments and utilizing recently evaluated nonideal mixing properties of garnet nonideal mixing parameters of biotite including fe mg al vi and ti and of cordierite involving fe and mg are evaluated in terms of iterative multiple least square regressions of the experimental results assuming the presence of ferric fe in biotite in relation to the coexisting fe oxide phases case a and assuming the absence of ferric fe in biotite case b two formulae of garnet biotite thermometer have been derived the garnet cordierite geothermometer was constructed using margules parameters of garnet adopted in the garnet biotite geothermometers the newly calibrated garnet biotite and garnet cordierite thermometers clearly show improved conformity in the calculated temperatures the thermometers give temperatures that are consistent with each other using natural garnet biotite cordierite assemblages within 50 c the effects of ferric fe in biotite on garnet biotite thermometry have been evaluated comparing the two calibrations of the thermometer the effects are significant it is clarified that taking ferric fe content in biotite into account leads to less dispersion of thermometric results

kumdykolite kokchetavite and cristobalite crystallized in nanogranites from felsic granulites orlica snieznik dome bohemian massif not evidence for ultrahigh pressure conditions a unique assemblage including kumdykolite and kokchetavite polymorphs of albite and k feldspar respectively together with cristobalite micas and calcite has been identified in high pressure granulites of the orlica snieznik dome bohemian massif as the product of partial melt crystallization in preserved nanogranites previous reports of both kumdykolite and kokchetavite in natural rocks are mainly from samples that passed through the diamond stability field however because the maximum pressure recorded in these host rocks is 3 gpa our observations indicate that high pressure is not required for the formation of kumdykolite and kokchetavite and their presence is not therefore an indicator of ultrahigh pressure conditions detailed microstructural and microchemical investigation of these inclusions indicates that such phases should instead be regarded as 1 a direct mineralogical criteria to identify former melt inclusions with preserved original compositions including h2o and co2 contents and 2 indicators of rapid cooling of the host rocks thus the present study provides novel criteria for the interpretation of melt inclusions in natural rocks and allows a more rigorous characterization of partial melts during deep subduction to mantle depth as well as their behavior on exhumation

distribution of surface pebbles with changes in wave energy on a sandy estuarine beach abstract a 29 day field experiment in delaware bay nj identified the dispersion of surface pebbles due to cross shore transport on a mesotidal estuarine beach composed mainly of sand wave heights were 0 04 0 56 m dissipation of wave energy on the low tide terrace increases as water levels become lower creating a spatial gradient in wave energy delivered to the foreshore analysis of surface sediment samples taken daily at 4 m intervals across the foreshore and two experiments using dyed pebbles as tracers document increasing quantities of pebbles with distance downslope on the beach corresponding to the decreasing energy gradient there is a second locus of high pebble concentration near the upper limit of swash at high water numbers of surface pebbles are at a minimum following high energy events wind speed 8 0 m s wave height 0 3 m the most conspicuous pebble accumulations result from low energy conditions wind speed 3 0 m s wave height 0 2 m pebbles move up and down the foreshore within the beach step they accumulate just above the low tide terrace on the falling tide when wave energy diminishes at low water under both storm and nonstorm conditions finer particles are moved onshore from this location by low energy post storm accretional waves and offshore by outflow from the beach water table leaving pebbles as a surface lag a fraction of these pebbles is moved up the beach by the swash of low energy waves or within the beach step in subsequent tidal cycles there is insu ficient sand in the backwash of low energy waves to bury pebbles they project into the flow of the swash and have low pivoting angles increasing the probability of entrainment and movement over the sand particles to the upper limit of swash

peak metamorphic temperatures from cation diffusion zoning in garnet a model that relates the characteristic diffusion length and average cooling rate to peak temperature was developed for chemical diffusion in spherical geometries on the basis of geospeedometry principles and diffusion theory the model is quantitatively evaluated for cation diffusion profiles in garnet important model parameters were calibrated empirically using diffusion zoning of ca in garnet from the pikwitonei granulite domain a terrane for which the thermal history has been well characterized the results are used i to empirically test diffusion parameters for mg and fe ii and ii to develop a tool that uses the diffusion zoning of these cations in garnet to constrain peak temperature conditions for garnet bearing rocks the thermometric approach was externally tested by applying it to garnet crystals from various metamorphic terranes worldwide and comparing the results to published peak temperature estimates the results overlap within uncertainties in all cases but result that are based on fe ii and mg chemical diffusion profiles are up to three times more precise than those acquired by conventional methods the remarkable consistency of the results implies that the model is robust and provides a reliable means of estimating peak temperatures for different types of high grade metamorphic rock the tool could be of particular advantage in rocks where critical assemblages for conventional thermometry do not occur or have been replaced during retrogression

factors controlling sediment yield from small intensively cultivated catchments in a temperate humid climate abstract data on sediment yield from 26 small cultivated catchments 10 10 000 ha in central belgium were collected based on sedimentation rates in small flood retention ponds area specific sediment yield varies from 0 4 to 20 6 t ha 1 year 1 for catchments ranging from 7 to 4873 ha various catchment properties were analysed in order to understand this large variation in sediment yield catchment area alone explains 64 of the observed variance in area specific sediment yield although no other parameter could explain more it is concluded that catchment area is not a valid parameter to link with sediment yield overall catchment geomorphology e g presented by the hypsometric integral is much more important in controlling sediment yield the lack of data however made this not very clear a multiple regression model including three morphological catchment properties is a valuable tool to predict total sediment yield t year 1 from catchments in central belgium this model has an efficiency of 0 81 furthermore it was concluded that the within catchment spatial distribution of parameters for instance slope steepness is very important but difficult to obtain one single representative value the use of spatially distributed erosion and sediment delivery models is therefore necessary accurate sediment yield data like the one presented in this study however are needed to validate these models

cordierite as a sensor of fluid conditions in high grade metamorphism and crustal anatexis cordierite h2o and co2 volatile saturation surfaces derived from recent experimental studies are presented for p t conditions relevant to high grade metamorphism and used to evaluate fluid conditions attending partial melting and granulite formation the volatile saturation surfaces and saturation isopleths for both h2o and co2 in cordierite are strongly pressure dependent in contrast the uptake of h2o by cordierite in equilibrium with melts formed through biotite dehydration melting controlled by the distribution of h2o between granitic melt and cordierite dw dw wt h2o melt wt h2o crd is mainly temperature dependent dw 2 5 6 0 for the h2o contents 0 4 1 6 wt percentage typical of cordierite formed through biotite dehydration melting at 3 7 kbar and 725 900 c this range in dw causes a 15 30 relative decrease in the total wt of melt produced from pelites cordierite in s type granites are h2o rich 1 3 1 9 wt and close to or saturated in total volatiles signifying equilibration with crystallizing melts that achieved saturation in h2o in contrast the lower h2o contents 0 6 1 2 wt percentage preserved in cordierite from many granulite and contact migmatite terranes are consistent with fluid absent conditions during anatexis in several cases including the cooma migmatites and broken hill granulites the cordierite volatile compositions yield ah2o values 0 15 0 4 and melt h2o contents 2 2 4 4 wt compatible with model dehydration melting reactions in contrast h2o leakage is indicated for cordierite from prydz bay antarctica that preserve h2o contents 0 5 0 3 wt which are significantly less than those required 1 0 0 8 wt for equilibrium with melt at conditions of 6 kbar and 860 c the co2 contents of cordierite in migmatites range from negligible 0 1 wt to high 0 5 1 0 wt and bear no simple relationship to preserved cordierite h2o contents and ah2o in most cases the cordierite volatile contents yield total calculated fluid activities ah2o aco2 that are significantly less than those required for fluid saturation at the p t conditions of their formation whether this reflects fluid absence dilution of h2o and co2 by other components or leakage of h2o from cordierite is an issue that must be evaluated on a case by case basis

how large are departures from lithostatic pressure constraints from host inclusion elasticity minerals trapped as inclusions within other host minerals will develop non lithostatic pressures during both prograde and retrograde metamorphism because of the differences between the thermoelastic properties of the host and inclusion phases there is only a single possible path in p t space the entrapment isomeke along which no residual pressure would be developed in a host inclusion system non lithostatic pressures are developed in inclusions as a result of the external pressure and temperature deviating from the isomeke that passes through the entrapment conditions with modern equation of state and elasticity data for minerals now available it is possible to perform precise calculations of the isomekes for mineral pairs these show that isomeke lines are not straight lines in p t space at metamorphic conditions we show that silicate inclusions in silicate hosts tend to have flat isomekes with small values of because of the small range of thermal expansion coefficients of silicate minerals as a consequence the general behaviour under decompression is for soft silicate inclusions in stiffer hosts to develop excess pressures whereas a stiff silicate inclusion in a softer matrix will experience lower pressures than lithostatic pressure the opposite effects occur for compression after entrapment on the prograde path the excess pressures in inclusions including allowance for mutual elastic relaxation of the host and inclusion are most easily calculated by using the isomeke as a basis analysis of the simplest possible model of a host inclusion system indicates that deviations from lithostatic pressure in excess of 1 gpa can be readily produced in quartz inclusions within garnet in metamorphic rocks for softer host minerals such as feldspar the pressure deviations are smaller because of greater elastic relaxation of the host the maximum pressure deviation from lithostatic pressure in the host phase around the inclusion is one third of the pressure deviation in the inclusion routines for performing these calculations have been added to the eosfit7c software package

fluid inclusions in high grade anatectic metamorphites fluid inclusions have been studied by microthermometry in metapelites and metabasites which have undergone partial melting in the transition zone from amphibolite to granulite facies mobilizates contain far more abundant and larger fluid inclusions than non mobilized or restite layers and these inclusions occur as several generations of well defined and chemically contrasted fluids carbonic co 2 ch 4 and hydrocarbon aqueous h 2 o nacl and n 2 a garnet bearing mobilizate in amphibolite contains 4 generations of relatively pure fluids most of them trapped after peak metamorphic conditions in the following p t domains co 2 and n 2 p 2 8 kbar t 550 850 c ch 4 p 1 2 kbar t 400 550 c h 2 o p t 120 400 c

ti diffusion in quartz abstract we have measured ti diffusion in quartz under dry 1 atm conditions experiments were performed using synthetic and natural quartz and a tio2 powder source with ti profiles obtained by rutherford backscattering spectrometry rbs over the temperature range 700 1150 c the following arrhenius relation was obtained for diffusion parallel to 001 d ti 7 10 8 exp 273 12 kj mol 1 r t m 2 sec 1 similar diffusivities were obtained for both synthetic and natural quartz and for a range of ti source materials including natural titanite powder and rutile quartz single crystal diffusion couples although ti diffusion appears slightly slower in the direction normal to c this difference is not great using these diffusion parameters calculations indicate that distances over which diffusional alteration of ti concentrations in quartz could occur in a million years would be on order of 500 m at 800 c and 15 m at 600 c the arrhenius relation above should be broadly applicable and may find application in constraining metamorphic histories under conditions where the ti in quartz geothermometer can be reasonably applied this relation can also be used to constrain peak temperatures and cooling histories from observations of exsolved rutile needles in quartz and the width of the ti depleted zone that develops around the growing needles finally these findings may find utility in evaluating crystal residence times in magmatic systems when coupled with observations of the sharpness of zoning patterns in quartz

oxidation state of the mantle abstract phase equilibrium relations are established in a system mg fe si h o with and without c at high pressures and temperatures high pressure temperature equations of state for the fluids including non ideal mixing are used in the calculations the computed equilibrium data show that an olivine of appropriate mantle composition 10 to 14 mole fayalite is stable over a wide range of temperature and oxygen fugacities in the carbon free system if c is introduced such that the equilibrium assemblage may contain graphite or diamond the fluid phase in the peridotite water system consists mostly of h2o and little co2 and ch4 however the fluid composition is strongly affected by the fe content of the system if fe is increased within 10 by moles of the total fe in the mantle from undersaturation i e no free fe present in equilibrium to that of saturation i e fe stable as a phase the ch4 content of the fluid changes from a low of 1 to a high of 89 the calculated results show a fluid with as much as 75 methane could be in equilibrium with olivine 13 mole fayalite without metallic fe as a coexisting phase the fo2 of the primitive mantle with such a fluid composition would be several log units below that of the quartz fayalite magnetite buffer

fluid inclusions in granulite facies metapelites of the hercynian ancient lower crust of the serre calabria southern italy investigations of fluid inclusions in granulitefacies metapelites of southern calabria enable characterization of the fluid composition of these lower crustal rocks and constrain the petrologically deduced retrograde p t path characterized by isothermal uplift prior to isobaric cooling in middle crustal levels fluid inclusions in cordierite garnet and sillimanite have a co2 rich composition inclusions in cordierite rarely contain minor amounts of n2 and h2o and in garnets some co2 ch4 n2 inclusions have been analyzed by raman microprobe quartz reveals the most complex fluid melusion compositions 1 co2 rich 2 co2 ch4 n2 3 ch4 n2 4 h2o mgcl2 cacl2 nacl 5 h2o nacl and 6 h2o co2 the earliest fluid inclusions after peak metamorphism are rich in co2 with minor amounts of n2 and h2o an early co2 h2o n2 fluid composition has been confirmed by detection of co2 h2o and n2 in the channels of the cordierite structure most of the early co2 rich fluid inclusions were modified during the uplift from the lower to the middle crustal level resulting in a density decrease with co2 still dominant the subsequent isobaric cooling led to further modifications of the fluid inclusions high density inclusions around implosion textures or scattered amongst lower density ones must have formed during this cooling episode aqueous inclusions in quartz are mostly formed late and are consistent with trapping during retrograde rehydration

package fluids 1 computer programs for analysis of fluid inclusion data and for modelling bulk fluid properties the computer package fluids contains five sets of computer programs written in c for the calculation of fluid properties both model fluids and data from fluid inclusions can be analysed in the programs bulk density molar volume and composition of fluid inclusions are calculated with the program bulk which uses microthermometric data micro raman spectroscopic data cation ratios and volume fraction estimations as input the program offers a broad variety of equations of state which are selected according to the fluid system or the temperature and pressure conditions of interest the isochores that correspond to the output or test v x properties of fluid inclusions are calculated by the program isoc in calculating the isochores this program takes account of the compressibility and expansion of selected host minerals the program test allows different equations of state to be compared directly with experimental data thereby facilitating selection of the most adequate model in the programs bulk and isoc loner is a group of programs that handle individual equations of state eos for all fluid systems presented in the programs bulk and isoc aqso is a group of programs that allows purely empirical modelling of electrolyte bearing aqueous solutions henry s law for dilute gas bearing aqueous solutions and osmotic coefficients for dilute electrolyte bearing aqueous solutions the programs are available on the university of leoben web site at http www unileoben ac at buero62 minpet ronald

modelling storm impacts on beaches dunes and barrier islands a new nearshore numerical model approach to assess the natural coastal response during time varying storm and hurricane conditions including dune erosion overwash and breaching is validated with a series of analytical laboratory and field test cases innovations include a non stationary wave driver with directional spreading to account for wave group generated surf and swash motions and an avalanching mechanism providing a smooth and robust solution for slumping of sand during dune erosion the model performs well in different situations including dune erosion overwash and breaching with specific emphasis on swash dynamics avalanching and 2dh effects these situations are all modelled using a standard set of parameter settings the results show the importance of infragravity waves in extending the reach of the resolved processes to the dune front the simple approach to account for slumping of the dune face by avalanching makes the model easily applicable in two dimensions and applying the same settings good results are obtained both for dune erosion and breaching

identification of spatio seasonal hydrogeochemical characteristics of the unconfined groundwater in the red river delta vietnam abstract groundwater has been the primary source of daily water supplies for people living in the red river delta the second largest delta in vietnam for this reason identification of hydrogeochemical properties of the groundwater is indispensable for sustainable utilization of groundwater sources in this study the spatio seasonal hydrogeochemical characteristics of groundwater in the unconfined aquifer of the red river delta have been investigated by systematically applying self organizing maps som and gibbs diagrams the groundwater chemistry dataset used in the analysis is composed of eight major dissolved ions i e ca2 mg2 na k hco 3 cl so 4 2 and co 3 2 and total dissolved solids that are collected from 47 groundwater monitoring wells within the study area during the dry and rainy seasons the som application classified the hydrogeochemical data into five clusters which revealed three basic representative water types high salinity one cluster low salinity two clusters and freshwater two clusters the spatial distribution of clusters and water types were identified in particular the low salinity type was found not only in the downstream area but also in the northeastern parts of the upstream and middle stream areas where the groundwater was mainly classified into one specific cluster in which agricultural activities were considered to influence groundwater chemistry cluster changes from the dry to rainy seasons were detected in approximately one fifth of the observations wells dilution by surface water may significantly affect the chemical characteristics of the unconfined aquifer during the rainy season based on gibbs diagrams rock weathering was found to be the main process in the evolution of chemical composition of freshwater type whereas the chemical structure of the low and high salinity types was primarily controlled by saltwater intrusion or anthropogenic activities

regional granulite facies metamorphism in the ivrea zone is the mafic complex the smoking gun or a red herring one widely accepted paradigm for the development of continental lower crust is that regional granulite facies metamorphism is caused by intrusion of mafic magma beneath or into the crust magmatic accretion the amphibolite to granulite facies supracrustal section exposed in the ivrea zone southern alps northern italy is commonly cited as a classic example establishing this postulated genetic relationship our interpretation of the pattern of metamorphic isograds compositional trends in high grade metasedimentary rocks and textural evidence in metapelite however indicates that final emplacement of the mafic plutonic rocks the mafic complex occurred subsequent to the regional thermal maximum field and petrographic relations suggest that a spatially restricted contact melting event in crustal rocks accompanied the emplacement of the mafic complex this inference is consistent with leucosome compositions in migmatites and a low pressure high temperature metamorphic overprint recorded by mineral assemblages in wall rocks proximal to the intrusion therefore evidence of anatexis and metamorphism of crustal rocks associated unequivocally with emplacement of the mafic complex is found only within an 2 km wide contact aureole overlying the intrusion the narrow aureole associated with emplacement of the mafic complex demonstrates that in some cases emplacement of large volumes of mafic magma within the crust does not inexorably lead to regional scale granulite facies metamorphism and large ion lithophile element depletion by melt loss

using detrital garnet compositions to determine provenance a new compositional database and procedure detrital garnet compositions can be used to help determine the provenance of sedimentary rocks in this study a garnet compositional database consisting of more than 2500 wet chemical and electron microprobe analyses was compiled from the literature for the garnets in the database the six principal garnet end member compositions pyrope almandine spessartine uvarovite grossular and andradite were calculated a multi stage methodology was devised to match garnet compositions to source rocks and a series of garnet provenance fields on ternary plots were identified the method was tested using compositional data from detrital garnet studies in several areas where provenance has already been identified with good results the methodology was then used to assess the provenance of detrital garnets from neogene sandstones of northern sabah borneo for which provenance is unknown and in a region where there are few garnet analyses for comparison comparison of garnet compositions from possible sources on palawan philippines and in borneo combined with the ternary plots excludes some known garnet bearing rocks as potential sources and suggests derivation of metamorphic and igneous garnets from palawan during the early miocene

ti diffusion in quartz inclusions implications for metamorphic time scales quartz inclusions in garnet from samples collected from the staurolite zone in central new england are zoned in cathodoluminescence cl the cl intensity is interpreted to be a proxy for ti concentration and the zoning attributed to ti diffusion into the quartz grains driven by ti exchange between quartz and enclosing garnet as a function of changing temperature the cl zoning has been interpreted using a numerical diffusion model to constrain the time scales over which the diffusion has occurred temperature time histories are sensitive to the presumed peak temperature but not to other model parameters the total time of the metamorphic heating and cooling cycle from around 450 c to the peak temperature 550 600 c back to 450 c is surprisingly short and encompasses only 0 2 2 million years for peak temperatures of 600 550 c the metamorphism was accompanied by large scale nappe and dome formation and it is suggested that this occurred as a consequence of in sequence thrusting resulting in a mid crustal ductile duplex structure

stability of andalusite and sillimanite and the al_ 2 sio_ 5 triple point constraints from the ballachulish aureole scotland andalusite and and sillimanite sil occur in well defined zones in the ballachulish aureole in most of the aureole s sillimanite bearing rocks sillimanite grain diameters range from 2 m to 10 m the boundary between prograde andalusite and prograde sillimanite is constrained to a zone of max 30 m width upgrade of the muscovite quartz andalusite k feldspar h 2 o reaction isograd this boundary is interpreted to correspond to the and sil equilibrium the common occurrence of andalusite well upgrade of the first occurrence of sillimanite is ascribed to sluggish kinetics of the polymorphic inversion the p t position of the and sil equilibrium in the aureole is estimated as 645 20 c and 3 0 0 4 kbar based on a combination of 1 location of the ms qtz and kfs h 2 o reaction corrected for non end member fluid and mineral compositions and 2 independent pressure estimates obtained from equilibria in metapelites marbles calcsilcates and granitoids all in exce

hillslope chemical weathering across parana brazil a data mining gis hybrid approach article i nfo self organizing map som and geographic information system gis models were used to investigate the nonlinear relationships associated with geochemical weathering processes at local 100 km 2 and regional 50 000 km 2 scales the data set consisted of 1 22 b horizon soil variables p c ph al total acidity ca mg k total cation exchange capacity sum of exchangeable bases base saturation cu zn fe b s mn gammaspectrometry total count potassium thorium and uranium and magnetic susceptibility measures and 2 six topographic variables elevation slope aspect hydrological accumulated flux horizontal curvature and vertical curvature it is characterized at 304 locations from a quasi regular grid spaced about 24 km across the state of parana this data base was split into two subsets one for analysis and modeling 274 samples and the other for validation 30 samples purposes the self organizing map and clustering methods were used to identify and classify the relations among solid phase chemical element concentrations and gis derived topographic models the correlation between elevation and k means clusters related the relative position inside hydrologic macro basins which was interpreted as an expression of the weathering process reaching a steady state condition at the regional scale locally the chemical element concentrations were related to the vertical curvature representing concave convex hillslope features where concave hillslopes with convergent flux tends to be a reducing environment and convex hillslopes with divergent flux oxidizing environments stochastic cross validation demonstrated that the som produced unbiased classifications and quantified the relative amount of uncertainty in predictions this work strengthens the hypothesis that at b horizon steady state conditions the terrain morphometry were linked with the soil geochemical weathering in a two way dependent process the topographic relief was a factor on environmental geochemistry while chemical weathering was for terrain feature delineation

metamorphic evolution of the coesite bearing ultrahigh pressure terrane in the north qaidam northern tibet nw china widespread evidence for ultrahigh pressure uhp metamorphism is reported in the dulan eclogite bearing terrane the north qaidam altun hp uhp belt northern tibet this includes 1 coesite and associated uhp mineral inclusions in zircon separates from paragneiss and eclogite identified by laser raman spectroscopy 2 inclusions of quartz pseudomorphs after coesite and polycrystalline k feldspar quartz in eclogitic garnet and omphacite and 3 densely oriented sio2 lamellae in omphacitic clinopyroxene these lines of evidence demonstrate that the dulan region is a uhp metamorphic terrane in the north dulan belt ndb eclogites are characterized by the peak assemblage grt omp rt phn coe pseudomorph and retrograde symplectites of cpx ab and hbl pl the peak conditions of the ndb eclogites are p 2 9 3 2 gpa and t 631 687 c the eclogite shows a near isothermal decompression p t path suggesting a fast exhumation in the south dulan belt sdb three metamorphic stages are recognized in eclogites 1 a peak eclogite facies stage with the assemblage grt omp ky rt phn at p 2 9 3 3 gpa and t 729 746 c 2 a high pressure granulite facies stage with grt cpx jd 30 pl an24 29 scp at p 1 9 2 0 gpa t 873 948 c and 3 an amphibolite facies stage with the assemblage hbl pl ep czo at p 0 7 0 9 gpa and t 660 695 c the clockwise p t path of the sdb eclogites is different from the near isothermal decompression p t path from the ndb eclogites which suggests that the sdb was exhumed to a stable crustal depth at a slower rate in essence these two sub belts formed in different tectonic settings they both subducted to mantle depths of around 100 km but were exhumed to the earth s surface separately along different paths this uhp terrane plays an important role in understanding continental collision in north western china

c o h n salt fluids associated with contact metamorphism mcgerrigle mountains quebec a raman spectroscopic study abstract contact metamorphism and metasomatism of a sequence of cambro ordovician pelitic calcareous and psammitic metasediments in the thermal aureole of the devonian mcgerrigle pluton has resulted in the generation of a wide variety of fluid compositions which can be described by the system c o h n salt microthermometric and raman spectroscopic data on fluid inclusions trapped in quartzsulfide veins adjacent to the intrusive contact indicate that three fluid types existed in the aureole 1 h 2 o 2 h 2 o co 2 and 3 ch 2 n 2 co 2 the aqueous fluids have salinities which range from 0 to 50 eq wt nacl cacl 2 this range in fluid compositions resulted from the progressive devolatilization of a variety of lithologies and the release of waters from the intrusion the range in salinity of the aqueous fluids is attributed to variable contributions of high salinity waters from the intrusions and lower salinity dehydration and formation waters some of the co 2 may be orthomagmatic however most of it probably came from decarbonation of calcareous and possibly carbonaceous lithologies ch 4 and n 2 were generated in pelitic units during thermal metamorphism ch 4 from reactions involving bitumen and graphite and n 2 from nh 2 in silicate minerals and possibly from bitumen the restriction of high mole fractions of ch 4 and n 2 to water free fluid inclusions can be explained by fluid immiscibility within the fracture system the partitioning of co 2 between water poor and water rich fluids was less extreme and in some cases co 2 and h 2 o may have been completely miscible

fluid inclusions as microchemical systems evidence and modelling of fluid host interactions in plagioclase dense co2 rich fluid inclusions hosted by plagioclases an45 to an54 of the o v gruber anorthosite body central dronning maud land east antarctica contain varying amounts of small calcite paragonite and pyrophyllite crystals detected by raman microspectroscopy these crystals are reaction products that have formed during cooling of the host and the original co2 rich h2o bearing enclosed fluid variable amounts of these reaction products illustrates that the reaction did not take place uniformly in all fluid inclusions possibly due to differences in kinetics as caused by differences in shape and size or due to compositional variation in the originally trapped fluid the reaction albite 2anorthite 2h2o 2co2 pyrophyllite paragonite 2calcite was thermodynamically modelled with consideration of different original fluid compositions although free h2o is not detectable in most fluid inclusions the occurrence of oh bearing sheet silicates indicates that the original fluid was not pure co2 but contained significant amounts of h2o compared to an actual fluid inclusion it is obvious that volume estimations of solid phases can be used as a starting point to reverse the retrograde reaction and recalculate the compositional and volumetrical properties of the original fluid isochores for an unmodified inclusion can thus be reconstructed leading to a more realistic estimation of p t conditions during earlier metamorphic stages or fluid capturing

metamorphism and anatexis in the mafic complex contact aureole ivrea zone northern italy emplacement of mantle derived magma magmatic accretion is the total thermal budget of the continental lower crust often presumed or inferred to be an important cause of regional produce regional granulite facies metamorphism and granulite facies metamorphism and crustal anatexis the juxgenerate yand heavy rare earth element hree taposition of mafic cumulates and regionally distributed granulite depleted granitoids ellis 1987 accretion of mafic facies rocks has led some to consider the ivrea zone northern italy magma and migration of partial melt will internally southern alps as an important exposure that demonstrates this stratify chemically differentiate and deplete the concausal relationship however regional ptt paths indicated by tinental lower crust in large ion lithophile elements metamorphic reaction textures and pt conditions inferred from lile magmatic accretion has been invoked to provide geothermobarometry indicate that the emplacement of mafic plutonic the heat and mass necessary for sustained magmatism in rocks mafic complex at the ivrea zone occurred during detectonic settings such as phanerozoic extensional terranes compression from ambient pressures at the regional thermal maximum lister et al 1986 gans 1987 fountain 1989 mareschal field and petrographic observations supported by pt estimates bergantz 1990 jarchow et al 1993 and magmatic indicate that regional retrograde decompression and emplacement of arcs hamilton 1981 kay kay 1981 bohlen the upper parts of the mafic complex probably accompanied lindsley 1987 hildreth moorbath 1988 extension during the late carboniferous early permian a spatially however as few exposed sections of lower continental restricted decompression melting event accompanied final emcrust show contiguous mafic intrusions and regionally placement depleting supracrustal rocks enclosed by an 2 3 km distributed granulite facies rocks estimates of the extent aureole overlying the upper mafic complex by 20 30 granite of anatexis and metamorphism accompanying magmatic component the upper mafic complex provided the thermal energy accretion have relied on numerical and analog simto reset mineral assemblages and locally overprint the regional ulations these models yield disparate results depending prograde metamorphic zonation the limited extent of the contact on whether heat transfer within the mafic intrusion aureole suggests that magmatic accretion may not inexorably cause and surrounding country rocks is primarily convective regional metamorphism and crustal anatexis campbell turner 1987 huppert sparks 1988 or conductive marsh 1989 bergantz dawes 1994 barboza bergantz 1996 a comparison with field evidence is required to discriminate between the model

fe mg mixing in cordierite constraints from natural data and implications for cordierite garnet geothermometry in granulites from chemicaldata on 108 pairs of naturally occurring garnet and cordierite the interchange energy of fe mg mixing in cordierite wo and the free energy change of the exchange equilibrium feralrsiro t t zmgraiosiro y mgralrsiro yzferalosiro in the temperature range of 700 850 c have been extracted using standard methods of linear regression analysis the input thermochemical parameters for multicomponent camg fe mn garnet solid solutions are based on the updated and revised values after ganguly and saxena 1984 e g wr 2500 cal w w 3000 cal calculated on the basis of one third formula unit on the basis of the derived values at 710 760 800 and 850 c fe mg mixing in cordierite has been approximated to a symmetric regular solution the fe mg substitution shows positive deviation from ideality in cordierite with tzi 1 9 34 4 54kj mol of divalent cation the values derived for the free energy of mixing at xi d xi ds 0 5 are 3 26 kj at 700 c and 4 39 kl at 900 c the ag value in joules for the above equilibrium can be expressed as 15079 8 552 incorporating these parameters the geothermometric expression for the exchange equilibrium is

detecting decadal changes in enso using neural networks the present manuscript analyzes monthly equatorial pacific indices by using a specific neural algorithm the so called self organizing maps soms the main result is a change found in the nature of the transitions between cold to warm and warm to cold extreme events from 1950 to present around the late 1970s som is an unsupervised clustering technique which allows one to reduce high dimensional data space in this case three indices over 636 months in terms of a smaller set of three dimensional reference vectors 100 characterizing pertinent situations these reference vectors which are displayed on a two dimension map are closely related by a topological relationship leading us to discriminate la nina conditions from the opposite el nino conditions in a second step a hierarchical agglomerative clustering hac method is used to further group the reference vectors into a small number of clusters 12 whose spatial and temporal characteristics can be analyzed and interpreted in terms of physical parameters schematically these 12 clusters can be divided into two warm clusters six neutral or transition clusters and four cold clusters in each particular group warm neutral cold the clusters mainly differ from each other by the amplitude of the anomalies their spatial patterns and their temporal variability some clusters are found to be strongly linked to the boreal spring period while others have barely any records during that season other clusters are associated with records mainly observed either prior to or after 1980 this suggests that the method is able to identify changes in the variability of the tropical pacific basin observed on decadal time scales 1976 climate shift in our case each monthly record can be summarized by the cluster to which it belongs the temporal evolution of this value during extreme enso events shows similar patterns persistence in specific clusters and transition between groups of clusters associated with comparable el nino or la nina events the methodology described in the present study som plus hac is suggested to be useful both for seasonal enso predictability and for the detection of decadal changes in enso behavior

the origins of granulites a metamorphic perspective although many recent reviews emphasize a uniformity in granulite pressure temperature p t conditions and paths granulites in reality preserve a spectrum of important petrogenetic features which indicate diversity in their modes of formation a thorough survey of over 90 granulite terranes or occurrences reveals that over 50 of them record p t conditions outside the 7 5 1 kbar and 800 50 c average granulite regime preferred by many authors in particular an increasing number of very high temperature 900 1000 c terranes are being recognized both on the basis of distinctive mineral assemblages and geothermobarometry petrogenetic grid and geothermobarometric approaches to the determination and interpretation of p t histories are both evaluated within the context of reaction textures to demonstrate that the large range in p t conditions is indeed real and that both near isothermal decompression itd and near isobaric cooling ibc p t paths are important amphibolite granulite transitions promoted by the passage of co 2 rich fluids as observed in southern india and sri lanka are exceptional and not representative of fluid related processes in the majority of terranes it is considered on the contrary that fluid absent conditions are typical of most granulites at or near the time of their recorded thermal maxima itd granulites are interpreted to have formed in crust thickened by collision with magmatic additions being an important extra heat source erosion alone is not however considered to be the dominant post collisional thinning process instead the itd paths are generated during more rapid thinning 1 2 mm yr exposure related to tectonic exhumation during moderate rate or waning extension ibc granulites may have formed in a variety of settings those which show anticlockwise p t histories are interpreted to have formed in and beneath areas of voluminous magmatic accretion with or without additional crustal extension ibc granulites at shallow levels very rapid 5 mm yr extensional thinning subsequent to collision it is suggested that the preservation of ibc paths rather than itd paths in many granulites is primarily related to the rate and timescale of extensional thinning of thickened crust and that hybrid itd to ibc paths should also be observed most ibc granulites and probably many itd granulites have not been exposed at the earth s surface as a result of the tectonic episodes which produced them but have resided in the middle and lower crust for long periods of time 100 2000 ma following these events the eventual exhumation of most granulite terranes only occur through their incorporation in later tectonic and magmatic events unrelated to their formation

sediment yield variability in spain a quantitative and semiqualitative analysis using reservoir sedimentation rates an existing dataset of area specific sediment yield ssy for 60 catchments in spain that was retrieved from sediment deposition rates in reservoirs avendano salas c sanz montero e rayan c gomez montana 1997 sediment yield at spanish reservoirs and its relationship with the drainage basin area in proceedings of the 19th symposium of large dams florence 1997 icold international committee on large dams pp 863 874 reveals that catchment area alone explains only 17 of the variability in ssy in this study an attempt to explain the remaining variability in ssy was made using a quantitative and a semiqualitative approach for 22 catchments during a field survey the 22 selected catchments were characterised by topography vegetation cover lithology shape and the presence of gullies in the broad vicinity of the reservoir this information was used to develop a factorial scoring index model that provides a fairly accurate and reliable prediction of ssy a classical multiple regression model using climatic topographic and land use properties derived from regional datasets could not explain as much variance as the qualitative index model nor did it appear to be as reliable the same conclusion could be drawn when using the corine soil erosion risk map of southern europe the low prediction capability of the multiple regression models and the corine soil erosion risk map could be attributed mainly to the fact that these methods do not incorporate gully erosion and that the land cover data are not a good representation of soil cover both variables have been shown to be of great importance during the field surveys future assessments of ssy could be quickly and efficiently made using the proposed factorial scoring index model in comparison with other models which demand more data the index model offers an alternative prediction tool d 2002 elsevier science b v all rights reserved

analysis of earthquake induced groundwater level change using self organizing maps for a better understanding of possible physical links between geophysical observables and earthquake characteristics it is important to analyze statistical spatiotemporal patterns in nature related to such events for this purpose characteristic changes in groundwater level gwl were observed before and after the 2016 kumamoto earthquake in japan previous research has shown that self organizing maps som can be used to classify complex patterns of gwl change during different parts of the earthquake sequence in this study we used before and after earthquake gwl data as input vectors to som in total 64 observed gwls were classified into 12 different clusters most shallow wells displayed gwl difference that was small during the foreshock first earthquake and large during the main shock second earthquake upstream deep wells showed relatively large difference in water level from 1 to 2 days after the earthquakes the gwl rapidly increased just after the earthquake then tended to gradually decrease from september most of the shallow wells in the unconfined aquifer rapidly recovered to initial gwls within several hours to several days because of hydrostatic pressure however most of the deep wells in the confined aquifer needed longer time to recover in some cases several weeks to several months these findings are important for the physical understanding of earthquake effects on the groundwater environment disaster prevention and possibility for development of earthquake precursors

coesite inclusions and prograde compositional zonation of garnet in whiteschist of the hp uhpm kokchetav massif kazakhstan a record of progressive uhp metamorphism coarse grained whiteschist containing the assemblage garnet kyanite phengite talc quartz coesite is an abundant constituent of the ultrahigh pressure metamorphic uhpm belt in the kulet region of the kokchetav massif of kazakhstan garnet displays prograde compositional zonation with decreasing spessartine and increasing pyrope components from core to rim cores were recrystallized at t 380 c inner to 580 c outer at p 10 kbar garnet ilmenite geothermometry margarite quartz stability and mantles at t 720 760 c and ph20 34 36 kbar coesite graphite stability phengite geobarometer kfmash system reaction equilibria textural evidence indicates that rims grew during decompression and cooling within the qtz stability field silica inclusions quartz and or coesite of various textural types within garnets display a systematic zonal distribution cores contain abundant inclusions of euhedral quartz type 1 inclusions inner mantle regions contain inclusions of polycrystalline quartz pseudomorphs after coesite type 2 with minute dusty micro inclusions of chlorite and more rarely talc and kyanite in their cores intense radial and concentric fractures are well developed in the garnet intermediate mantle regions contain bimineralic inclusions with coesite cores and palisade quartz rims type 3 which are also surrounded by radial fractures subhedral inclusions of pure coesite without quartz overgrowths or radial fractures type 4 occur in the outer part of the mantle garnet rims are silica inclusion free type 1 inclusions in garnet cores represent the low p low t precursor stage to uhpm recrystallization and attest to the persistence of low p assemblages in the coesite stability field coesites in inclusion types 2 3 and 4 are interpreted to have sequentially crystallized by net transfer reaction kyanite talc garnet coesite h2o and were sequestered within the garnet with progressively decreasing amounts of intragranular aqueous fluid during the retrograde evolution of the rock all three inclusion types diverged from the host garnet p t path at the coesite quartz equilibrium and followed a trajectory parallel to the equilibrium boundary resulting in inclusion overpressure coesite in type 2 inclusions suffered rapid intragranular h2o catalysed transformation to quartz and ruptured the host garnet at about 600 c when inclusion p 27 kbar garnet host p 9 kbar instantaneous decompression to the host garnet p t path passed through the kyanite talc chlorite quartz reaction equilibrium resulting in the dusty micro assemblage in inclusion cores type 3 inclusions suffered a lower volumetric proportion transformation to quartz at the coesite quartz equilibrium and finally underwent rupture and decompression when t 400 c facilitating coesite preservation type 4 coesite inclusions are interpreted to have suffered minimal transformation to quartz and proceeded to surface temperature conditions along or near the coesite quartz equilibrium boundary

magmatic underplating extension and crustal reequilibration insights from a cross section through the ivrea zone and strona ceneri zone northern italy the thermal impact of magmatic underplating at various crustal levels is studied along a traverse through the ivrea verbano zone and strona ceneri zone in northern italy geochronological and petrologic data are compared to a two dimensional thermal kinematic model field data and numerical simulation show the strong disturbance of the temperature field in the lower and intermediate crust in relation to magmatic underplating leading to granulite to amphibolite facies metamorphism as well as reequilibration of mineral chemical and isotopic systems magmatic underplating leaves a crust with an apparently heterogeneous tectonometamorphic evolution as information on the earlier history is preserved only at upper crustal levels

proterozoic magmatic and tectonometamorphic evolution of the taratash complex central urals russia the taratash complex tc in the northernmost bashkirian anticlinorium middle urals is unique among the pre uralian polymetamorphic complexes along the eastern margin of the east european craton because it experienced granulite facies peak metamorphic conditions 850 900 c 10 kbar herein we constrain the post granulite facies polystage evolution of the complex which records various increments of the geodynamic history of the east european continental margin formation of granite and migmatite associated with amphibolite facies events are dated at 2 344 29 and 2 044 8 ma u pb zircon in different structural units at 1 810 41 ma the tc was affected by a greenschist facies retrogressive metamorphism which was probably related to a stage of granite formation in the eastern part of the east european craton this is confirmed by a u pb zircon age of 1 848 8 ma obtained from a sheared granite in the adjacent alexandrovskiy complex ac greenschist facies shear zones which separate different structural units of the tc formed before 1 350 ma partial re equilibration of rb sr and k ar isotope systems between 1 350 ma and 1 200 ma is attributed to fluid flow probably induced by anorogenic magmatism in the bashkirian anticlinorium meso to neoproterozoic basaltic dykes indicate that the tc had been exhumed to upper crustal levels at that time evidence for a grenvillian event or for the timanian orogeny which affected other pre uralian complexes in the urals is lacking uralian orogenic shortening and thrusting on devonian limestones is recorded by shear zones in the ac to the east of the tc and has been dated at 300 ma rb sr 40ar 39ar

evaluation of sedimentation vulnerability at small hillside reservoirs in the semi arid region of tunisia using the self organizing map small hillside reservoirs are fundamental for the sustainability of the water resources in the semi arid region of tunisia where the government has constructed small dams since 1990 however flash floods and severe erosion are jeopardizing the life of those small hydraulic structures prompting an assessment of the vulnerability of semi arid catchments to erosion in this study we investigated the degree of erosion in 23 catchments by considering six variables related to erosion the specific sediment yield the hypsometric integral the topographic index the rainfall related attribute as well as lithological and vegetation cover more importance was assigned to the hypsometric integral and how it controls erosion vulnerability the self organizing map of kohonen a robust clustering method was implemented to analyze the patterns of the six variables the results revealed four groups of catchments with different vulnerabilities to erosion in addition there is a global trend of increasing erosion risk from the southwest to the northeast of the semi arid region of tunisia

passive buoyant tracers in the ocean surface boundary layer 2 observations and simulations of microplastic marine debris this paper is the second of a two part series that investigates passive buoyant tracers in the ocean surface boundary layer osbl the first part examines the influence of equilibrium wind waves on vertical tracer distributions based on large eddy simulations less of the wave averaged navier stokes equation motivated by observations of buoyant microplastic marine debris mpmd this study applies the les model and the parametric one dimensional column model from part one to examine the vertical distributions of mpmd mpmd is widely distributed in vast regions of the subtropical gyres and has emerged as a major open ocean pollutant whose distribution is subject to upper ocean turbulence the models capture shear driven turbulence langmuir turbulence lt and enhanced turbulent kinetic energy input due to breaking waves bws model results are only consistent with observations of mpmd profiles and the relationship between surface concentrations and wind speed if lt effects are included neither bw nor shear driven turbulence is capable of deeply submerging mpmd suggesting that the observed vertical mpmd distributions are a characteristic signature of wave driven lt thus this study demonstrates that lt substantially increases turbulent transport in the osbl resulting in deep submergence of buoyant tracers the parametric model is applied to 11 years of observations in the north atlantic and north pacific subtropical gyres to show that surface measurements substantially underestimate mpmd concentrations by a factor of 3 13

clustering spatio seasonal hydrogeochemical data using self organizing maps for groundwater quality assessment in the red river delta vietnam summary the red river delta rrd is the second largest delta in vietnam and its local communities depend on groundwater sources for water supply a clear understanding of the groundwater hydrogeochemical properties particularly their changes from the dry to rainy seasons and spatial characteristics is invaluable and indispensable for the management and protection of this important water resource in this study self organizing maps was systematically applied for the first time to investigate the seasonal and spatial hydrogeochemical characteristics of groundwater in the pleistocene confined aquifer of the rrd the hydrogeochemical characteristics clustered by som were further examined using the gibbs diagrams the groundwater chemistry dataset used in the analysis comprised eight major dissolved ions i e ca 2 mg 2 na k hco 3 cl so 4 2 and co 3 2 and total dissolved solids that were collected from 52 groundwater monitoring wells within the study area during the dry and rainy seasons based on the results the hydrogeochemical groundwater data of the confined aquifer monitoring wells for the delta were classified into 8 clusters which revealed three basic representative water types high salinity 2 clusters low salinity 3 clusters and freshwater 3 clusters the high salinity types were located in the middle stream and coastal areas of the rrd while the low salinity types were observed near the western and northeastern boundaries of the delta cluster changes from the dry to rainy seasons were detected in approximately one third of the observation wells the increase in groundwater recharge during the rainy season is the main reason for these changes based on gibbs diagrams the source of soluble ions in the groundwater of the freshwater types was found to be the weathering of rock forming minerals while evaporation and marine activities leaching from salty paleowater and salt water intrusion were found to be the main factors affecting the chemistry of the groundwater characterized by the low and high salinity types respectively

fluids in metamorphic rocks abstract basic principles for the study of fluid inclusions in metamorphic rocks are reviewed and illustrated a major problem relates to the number of inclusions possibly formed on a wide range of p t conditions having also suffered in most cases extensive changes after initial trapping the interpretation of fluid inclusion data can only be done by comparison with independent p t estimates derived from coexisting minerals but this requires a precise knowledge of the chronology of inclusion formation in respect to their mineral host the three essential steps in any fluid inclusion investigation are described observation measurements and interpretation observation with a conventional petrographic microscope leads to the identification and relative chronology of a limited number of fluid types same overall composition eventually changes in fluid density for the chronology the notion of gis group of synchronous inclusions is introduced it should serve as a systematic basis for the rest of the study microthermometry measurements completed by nondestructive analyses mostly micro raman specify the composition and density of the different fluid types the major problem of density variability can be significantly reduced by simple considerations of the shape of density histograms allowing elimination of a great number of inclusions having suffered late perturbations finally the interpretation is based on the comparison between few isochores representative of the whole inclusion population and p t mineral data essential is a clear perception of the relative chronology between the different isochores when this is possible as illustrated by the complicated case of the granulites from central kola peninsula a good interpretation of the fluid inclusion data can be done if not fluid inclusions will not tell much about the metamorphic evolution of the rocks in which they occur

palaeozoic tectonic evolution of the middle urals in the light of the esru seismic experiments abstract a new compilation of deep seismic reflection data in combination with the results of recent geological and isotopic investigations provides the basis for significantly refined structural and evolutionary models of the middle urals many of the major structural boundaries observed at the surface e g main uralian thrust main uralian normal fault serov mauk fault prianitchnikova shear zone can be followed on the seismic reflection data to depths of 8 15 km only a few features can be traced through the horizontal to shallow dipping zones of middle crustal reflectivity that extend beneath much of the middle urals exceptions might be the deevo thrust and a newly discovered deep band of moderately dipping reflections beneath the west siberian basin that may represent the remnants of an ancient subduction zone the reflectivity of the lower crust and moho are similar beneath the hinterland of the urals and below the western part of the west siberian basin suggesting that in both places they have the same extensional origin accretion of various exotic terranes to the eastern margin of baltica during late palaeozoic time involved considerable shortening of the continental margin the accreted terranes e g tagil petrokamensk and alapaevsk arc complexes consist mostly of island arc material formed during mid and late palaeozoic time closely associated with the island arcs are several high grade metamorphic complexes e g salda and murzinka adui complexes that were exhumed during and after late palaeozoic convergence towards the end of the orogeny several north south trending strike slip faults e g sisert fault were active after the orogeny major periods of tectonism and magmatism in the middle urals resulted in the extrusion of the siberian trap basalts crustal stretching and or underplating and the formation of the west siberian basin the planet s largest intracontinental sedimentary basin finally a period of renewed thrust faulting often reactivating older faults led to the inversion of the mesozoic basins

distribution of fe2 and mg between coexisting garnet and hornblende in synthetic and natural systems an empirical calibration of the garnet hornblende fe mg geothermometer abstract multiple regression analysis of a compilation of the fe2 mg distribution between garnet and hornblende from experimental runs on basaltic to intermediate compositions n 22 and coexisting garnet clinopyroxene hornblende from natural intermediate to basaltic rocks n 43 has been performed to define ln kd fe2 mg grt hbl as a function of temperature and garnet composition the regression of data covering a large span in pressure 5 16 kbar temperature 515 1025 c and composition yields the ln kd fe2 mg grt hbl p t compositional relationship r2 0 93 t c 1504 1784 x ca grt x mn grt ln k d fe 2 mg grt hbl 0 720 273 where k d fe 2 mg grt hbl fe 2 mg grt fe 2 mg m 1 m 3 hbl x ca grt ca ca mn fe 2 mg in garnet x mn grt mn ca mn fe 2 mg in garnet application of this expression to natural garnet hornblende pairs in intermediate to basaltic and semipelitic rock types from various settings gives temperatures that are consistent with other methods

calculated fluid evolution path versus fluid inclusion data in the cohn system as exemplified by metamorphic rocks from rogaland south west norway fluid evolution paths in the cohn system can be calculated for metamorphic rocks if there are relevant data regarding the mineral assemblages present and regarding the oxidation and nitrodation states throughout the entire p t loop the compositions of fluid inclusions observed in granulitic rocks from rogaland south west norway are compared with theoretical fluid compositions and molar volumes the fluid parameters are calculated using a p t path based on mineral assemblages which are represented by rocks within the pigeonite in isograd and by rocks near the orthopyroxene in isograd surrounding an intrusive anorthosite massif the oxygen and nitrogen fugacities are assumed to be buffered by the coexisting fe ti oxides and cr carlsbergite respectively many features of the natural fluid inclusions including 1 the occurrence of co2 n2 rich graphite absent fluid inclusions near peak m2 metamorphic conditions 927 c and 400 mpa 2 the non existence of intermediate ternary co2 ch4 n2 compositions and 3 the low molar volume co2 rich fluid inclusions 36 42 cm3 mol 1 are reproduced in the calculated fluid system the observed co2 ch4 rich inclusions with minor n2 5 mol should also include a large proportion of h2o according to the calculations the absence of h2o from these natural high molar volume co2 ch4 rich inclusions and the occurrence of natural ch4 n2 rich inclusions are both assumed to result from preferential leakage of h2o this has been previously experimentally demonstrated for h2o co2 rich fluid inclusions and has also been theoretically predicted fluid deficient conditions may explain the relatively high molar volumes but cannot be used to explain the occurrence of ch4 n2 rich inclusions and the absence of h2o

the effect of wind mixing on the vertical distribution of buoyant plastic debris 1 micro plastic marine debris is widely distributed in vast regions of the subtropical gyres and has emerged as a major open ocean pollutant the fate and transport of plastic marine debris is governed by poorly understood geophysical processes such as ocean mixing within the surface boundary layer based on profile observations and a one dimensional column model we demonstrate that plastic debris is vertically distributed within the upper water column due to wind driven mixing these results suggest that total oceanic plastics concentrations are significantly underestimated by traditional surface measurements requiring a reinterpretation of existing plastic marine debris data sets a geophysical approach must be taken in order to properly quantify and manage this form of marine pollution

influence of configuration of bulkheads on use of estuarine beaches by horseshoe crabs and foraging shorebirds construction of bulkheads is a common response to erosion of estuarine shorelines bulkheads are usually built incrementally resulting in wider sandy beaches remaining as enclaves between bulkhead segments this paper measures the characteristics of bulkheads and enclaves and evaluates 1 whether horseshoe crabs limulus polyphemus utilize enclaves for spawning when they provide partial sheltering during periods of high wave energies and 2 whether eggs become trapped in the enclaves and are available to shorebirds when the beaches in front of bulkheads are inundated the characteristics of bulkheads and beach enclaves were identified in five developed reaches in delaware bay usa counts of horseshoe crabs were made in enclaves in two of these reaches during times of high wave energies and compared to counts in nearby unarmored segments egg tracer and trapping experiments were conducted at one of the enclaves to assess egg movement results indicate that the percent of bulkheads intersecting the beach below mid foreshore varies from 10 to 50 spawning densities were greater in enclaves than on longer unarmored segments on some days enclaves serve as a sink for eggs moving along the base of the bulkheads most birds feeding on horseshoe crab eggs preferred sites outside the enclaves and bulkhead segments any advantage of bulkheads creating enclaves and sinks for eggs moving alongshore is likely overridden by their disruption to natural process and habitats but having unarmored enclaves between bulkhead segments may be preferable to one continuous bulkhead based on environmental benefits

lost at sea where is all the plastic millions of metric tons of plastic are produced annually countless large items of plastic debris are accumulating in marine habitats worldwide and may persist for centuries 1 1 4 2 here we show that microscopic plastic fragments and fibers fig 1a 3 are also widespread in the

plastic pollution of the kuril kamchatka trench area nw pacific abstract during the german russian expedition kurambio kuril kamchatka biodiversity studies to the northwest pacific kuril kamchatka trench and its adjacent abyssal plain we found several kinds and sizes of plastic debris ranging from fishing nets and packaging to microplastic in the sediment of the deep sea floor microplastics were ubiquitous in the smaller fractions of the box corer samples from every station from depths between 4869 and 5766 m they were found on the abyssal plain and in the sediments of the trench slope on both sides the amount of microplastics differed between the stations with lowest concentration of 60 pieces per m2 and highest concentrations of more than 2000 pieces per m2 around 75 of the microplastics defined here as particles zenkevich 1963 yet we can only guess how these microplastics accumulated in the deep sea of the kuril kamchatka trench area and what consequences the microplastic itself and its adsorbed chemicals will have on this very special and rich deep sea fauna but we herewith present an evaluation of the different kinds of plastic debris we found as a documentation of human impact into the deep sea of this region of the northwest pacific

delivery and movement of horseshoe crab eggs limulus polyphemus in the breaking waves and swash uprush of an estuarine foreshore abstract knowledge of conditions for entrainment of eggs and larvae from beach spawning sites is critical in determining the likelihood that these food sources will be delivered to shorebirds the exhumation of horseshoe crab eggs buried within the beach foreshore is a function of changes in wave and current velocities over a tidal cycle this field study was conducted to evaluate the temporal constraints to egg release at two different locations across the foreshore of a sandy estuarine beach in delaware bay new jersey wind wave current characteristics beach change and eggs in transport were sampled over two tidal cycles egg counts were determined using four colors of dyed egg tracers placed as point sources 5 and 10 m bayward of the expected upper limit of swash tracer recovery varied from 1 to 18 of the tracer eggs buried wave heights were relatively low instrumented hs 0 09 0 17 m but with long periods 5 6 8 8 s results reveal that egg release is discontinuous and occurs in pulses when the swash and breakers migrate across the injection points on the rising tide and when the breakers migrate past the injection points during the falling tide a lack of tracer at the upper 5 m injection point after early stages of high tide is likely due to the maximum disturbance depth being achieved early leaving no eggs within the swash boundary layer peaks in recovery of tracer initially buried at the lower 10 m location after the breakers migrated up the foreshore well past the injection location are likely from eggs deposited in the wrack on the upper beach or reburied in the sediment near the upper limit of swash and remobilized by high swash uprushes these results using point sources of tracer eggs suggest that the contribution of eggs from within the beach matrix is temporally variable across the foreshore most eggs are released during rising tide but additional eggs can be released during falling tide if the depth of activation of the bed is greater than on the rise due to net erosion or change to higher wave energy conditions successful shorebird foraging at other times in the falling tide appears due to transport of eggs released earlier in the tidal cycle and delivered alongshore and not due to eggs exhumed in situ at that time

flow velocity and sediment transport in the swash zone of a steep beach detailed measurements of flow velocity and total sediment load were obtained in the swash zone on a steep beach swash motion was measured using ducted impeller flow meters and capacitance water level probes during wave uprush the onshore flow increased almost instantaneously from zero to its maximum velocity after the arrival of the leading edge of the swash lens and subsequently decreased gradually to zero for the remainder of the uprush during backwash the offshore flow increased steadily from zero to its maximum towards the end of the backwash and dropped rapidly to zero as the beach fell dry the duration of backwash was typically longer than that of uprush and maximum water depth on the beach was attained just prior to the end of the uprush the total sediment load was measured for 35 individual wave uprush events using a sediment trap the amount of sediment transported by a single uprush was typically two to three orders of magnitude greater than the net transport per swash cycle difference between uprush and backwash inferred from surveys of beach profile change the measured immersed weight total load transport rate displayed a strong relationship with the time averaged velocity cubed which is consistent with equations for both bedload transport and total load transport under sheet flow conditions the bagnold 1963 1966 bedload transport model was tested against our field data and yielded ib ku3tu tan tan where ib is the immersed weight of bedload transported during the entire uprush kg m 1 k is a coefficient kg m 4 s2 u is the time averaged flow velocity for the uprush m s 1 tu is the uprush duration s is the friction angle of the sediment and is the beach slope the empirically determined value for the coefficient k was 1 37 0 17

hydrodynamic forcing and sand permeability influence the distribution of anthropogenic microparticles in beach sediment abstract the distribution of anthropogenic microparticles mps such as plastic and natural fibres used in textiles in beach sediments was studied in a human influenced pocket beach in liguria nw mediterranean sea information on environmental parameters such as rainfall hydrodynamic characteristics and sediment texture was collected at the same time as the sediment samples the mps 416 202 mps kg 1 on average were mainly fibres 57 100 while fragments and spheres showed irregular abundances linked to the draining action of waves on the beach uni and multivariate statistical analyses highlighted that the different spatial and seasonal distribution of fibres primarily depended on the action of the waves that force seawater into the sand rather than on sedimentation following depositional processes wave height and direction had a role in fibre distribution in the sand as well as sediment permeability and sorting the occurrence of short term and spatially localised hydrodynamic events such as rip currents were observed to influence the abundance of fibres overlapping the seasonal sequences of beach accretion and erosion that is typical of the area and increasing fibre abundance by transporting those accumulated in the sediments of the submerged beach during winter

geomorphometric feature analysis using morphometric parameterization and artificial neural networks this paper presents a semi automatic method using an unsupervised neural network to analyze geomorphometric features as landform elements the shuttle radar topography mission srtm provided detai

uralian magmatism an overview abstract this paper is an attempt to summarize current knowledge of uralian magmatism focusing on those aspects relevant for understanding its geodynamic evolution the urals consist of three tectonomagmatic domains a suture sector in the west and two n s imbricated island arc continental sectors in the east the suture sector comprises lower palaeozoic mafic ultramafic complexes which show eastward impoverishment in lile thus reflecting the transition of the subcontinental lithospheric mantle of the russian plate to the suboceanic lithospheric mantle of the subducted uralian palaeo ocean the two island arc continental sectors represent the transition from oceanic to continental environments in the middle and south urals collisional magmatism started in the silurian and persisted till the permian migrating progressively eastward and increasing in abundance of lile and 87 sr 86 sr initial magmatic polarity is very similar to that of modern subduction zones and indicates that the subducted slab was dipping eastward during that period the northern and southern island arc continental sectors show many similarities regarding the nature and spatial temporal distribution of magmatism but there are also some important differences which probably indicate somewhat different geodynamic regimes in the northern sector carboniferous tonalite granodiorite batholiths have features compatible with an origin by melting of the oceanic crust in the subducted slab in the southern sector however carboniferous tonalite granodiorite batholiths have features more consistent with a melting event within the lower continental crust above the subduction zone than with melting within the subducted slab upper carboniferous permian granites have high 87 sr 86 sr initial in the north e g 0 7120 in the murzinka batholith but very low 87 sr 86 sr initial in the south e g 0 7045 in the dzhabyk batholith in spite of rocks from both batholiths being equally peraluminous and showing evidence of derivation by anatexis of metasediments the low 87 sr 86 sr initial at dzhabyk might indicate that in the southern sector the accretionary prism grew very rapidly thus allowing involvement in upper palaeozoic melting events

intelligent estimation of spatially distributed soil physical properties abstract spatial analysis of soil samples is often times not possible when measurements are limited in number or clustered to obviate potential problems we propose a new approach based on the self organizing map som technique this approach exploits underlying nonlinear relation of the steady state geomorphic concave convex nature of hillslopes from hilltop to bottom of the valley to spatially limited soil textural data the topographic features are extracted from shuttle radar topographic mission elevation data whereas soil textural clay silt and sand and hydraulic data were collected in 29 spatially random locations 50 to 75 cm depth in contrast to traditional principal component analysis the som identifies relations among relief features such as slope horizontal curvature and vertical curvature stochastic cross validation indicates that the som is unbiased and provides a way to measure the magnitude of prediction uncertainty for all variables the som cross component plots of the soil texture reveals higher clay proportions at concave areas with convergent hydrological flux and lower proportions for convex areas with divergent flux the sand ratio has an opposite pattern with higher values near the ridge and lower values near the valley silt has a trend similar to sand although less pronounced the relation between soil texture and concave convex hillslope features reveals that subsurface weathering and transport is an important process that changed from loss to gain at the rectilinear hillslope point these results illustrate that the som can be used to capture and predict nonlinear hillslope relations among relief soil texture and hydraulic conductivity data

evaluating raman spectra of carbonaceous matter by automated iterative curve fitting abstract raman spectroscopy of carbonaceous material rscm estimates the maximum metamorphic temperature of coal graphite and cm enclosed in metapelites however the evaluation of cm raman spectra is often biased by subjectivity which reduces the overall comparability of rscm results to decrease subjectivity an automated evaluation software is presented it is based on the iterative and simultaneous modeling of signal and baseline functions two new rscm parameters are introduced termed raman area ratio rar and scaled total area sta these parameters are tested on a sample suite of organic rich shales and slates of the teuschnitz syncline thuringia germany of well constrained very low to low metamorphic grade defined by illite crystallinty and vitrinite reflectance a correlation of both rscm parameters with vitrinite reflectance verifies that the rscm parameters reflect the metamorphic conditions this correlation prevails at different excitation wavelengths 488 nm 633 nm 785 nm used for the raman measurements

on the formation of granulites the tectonic settings for the formation and evolution of regional granulite terranes and the lowermost continental crust can be deduced from pressure temperature time p t time paths and constrained by petrological and geophysical considerations p t conditions deduced for regional granulites require transient average geothermal gradients of greater than 35 c km 1 implying minimum heat flow in excess of 100 mwm 2 such high heat flow is probably caused by magmatic heating tectonic settings wherein such conditions are found include convergent plate margins continental rifts hot spots and at the margins of large deep seated batholiths however particular p t time paths do not allow specific tectonic settings to be distinguished at this time under different conditions both clockwise cw pmax attained before tmax and anticlockwise acw pmax attained slightly after tmax paths are possible in the same tectonic setting both cw and acw end member paths can yield nearly isobaric cooling ibc paths such cooling paths are clearly not an artefact of thermobarometry but can be constrained by solid solid and devolatilization equilibria and geophysical modelling in terms of understanding the evolution of the deep crust a potentially significant group of regional granulite terranes are those that show evidence for acw ibc paths such paths are the likely result of i episodic igneous activity resulting in intrusions within all levels of the crust ii thickening of the crust by magmatic underplating iii slow uplift as a result of the formation of a deep garnet rich crustal root and iv excavation resulting from a later tectonic event unrelated to that resulting in the formation of the granulites the later event might be triggered by the delamination of the garnet rich lowermost crust

swash zone sediment suspension and transport and the importance of bore generated turbulence a study of swash zone sediment transport was conducted at gleneden beach oregon during february 25 28 1994 the data collected included suspended sediment concentration ssc sea surface elevation and velocity initially 4 and 8 cm above the bed at three cross shore locations within the swash zone spanning high tides ensemble averages of 6 9 and 12 s duration swash events showed that the uprush suspension was high concentrated in the leading edge and nearly vertically uniform above the lower 1 2 cm of the water column shortly after the sensors were inundated by run up the sediment rapidly settled out of the water during flow reversal the ssc was small but increased again in the backwash backwash vertical profiles were markedly different from uprush profiles with much of the suspension being confined to very near the bed where strong vertical gradients in ssc existed these marked differences show that the backwash is not simply the reverse of the uprush implying significant differences in the underlying fluid dynamics and sediment transport mechanisms backwash sediment suspension increased with flow duration however ensemble averaged ssc profiles of varying duration showed that the backwash concentrations were not consistent at the same temporal phases which suggests that water depth in addition to flow duration may be a controlling factor strong cross shore gradients in ssc suggest that bore derived turbulence may affect local sediment transport specifically our data show this bore generated turbulence turbulent kinetic energy directly influences local sediment suspension hence standard bed shear bagnold type sediment transport models may no longer be valid in the vicinity of the bore in the vicinity of the bore a higher correlation between bore generated turbulence and suspended sediment transport was found than between a bagnold type formulation and suspended sediment transport

rates of fe mg mn and ca diffusion in garnet extraction of the thermal and chemical histories preserved by modified compositional zoning in garnet is compromised by large uncertainties in experimentally determined diffusion coefficients for principal divalent cations some of this uncertainty derives from long down temperature extrapolations but much of it arises from an inability to account accurately for large variations in diffusivity as a function of garnet composition numerical simulation of stranded diffusion profiles in partially resorbed natural garnets constrains diffusivities at low temperature and reveals a systematic dependence of diffusion rates on host garnet composition a comprehensive model incorporating a simple compositional dependence allows accurate prediction of diffusion rates for fe mg mn and ca for nearly all garnet compositions across the full range of geologically relevant temperatures pressures and oxygen fugacities

high temperature reduced granulite facies nature of garnetites in the khabarny mafic ultramafic massif southern urals evidence from fluid and mineral analyses