impact of cyclic freezing on precipitation of silica in me sio2 h2o systems and geochemical implications for cryosoils and sediments abstract cyclic freezing of aqueous solutions may cause a significant precipitation of amorphous silica where about 90 mol of the primary dissolved silicic acid can be fixed in analogy to evaporation h 2 o molecules are separated from aqueous solutions by freezing and supersaturation with respect to amorphous silica can be reached the results show that higher proportions of silica precipitated at lower input si oh 4 concentration and at increasing numbers of freeze thaw cycles additionally dissolved metal ions me favour the formation of amorphous silica in the sequence of na 2 2 2 2 this may be mostly related to a decrease of amorphous silica solubility in the high concentrated aqueous solutions which remained after ice formation co precipitation yields me si ratios of the depositions between 1 and 4 re dissolution of the primary amorphous precipitates is incomplete accordingly such solids are suitable precursor materials for neoformation of silicates as secondary authigenic silicates like zeolites may be formed from such precursors it is suggested that their occurrence and exposure in cryosoils and sediments might be used as a proxy indicator of past climate cyclic freezing can significantly reduce the geochemical and ecological availability of silica on the other side the decrease of dissolved silica induced by freezing provokes an increase of undersaturation with respect to silicates in the re thawed soil or interstitial solutions which stimulates the dissolution of siliceous minerals and rocks

contact diagenesis the effect of an intrusion on reservoir quality in the triassic sherwood sandstone group northern ireland abstract intrusion of a dolerite sill into clay bearing arkosic triassic sherwood group sandstones with moderate porosity 22 and high but anisotropic permeability mode 500 md led to the progressive transformation of precursor diagenetic minerals in the host rock locally pore filling mg rich smectite saponite quartz and dolomite existing in the rock following earlier burial diagenesis reacted to produce grain coating flakes of talc at the lowest contact temperatures 130 180 c based on equilibrium reaction path and thermal history calculations at higher temperatures 200 230 c talc reacted with calcite to produce an actinolitic amphibole close to the intrusion at temperatures of 250 c bundles of acicular needles of actinolite protruding into open pores were produced by a second reaction involving saponite hematite and calcite framework feldspar minerals mainly k feldspars played little or no part in the reactions because there were no k al rich minerals produced by contact diagenesis and because the detrital feldspar grains are essentially unaltered thus while equilibrium may have been approached on the intrapore scale 10 m it was not achieved between grains e g detrital feldspars pore water and clays in the pores total porosity has been unaffected by the intrusion and consequent mineral reactions because reactions involved recrystallization of original pore filling minerals despite the contact diagenetic changes in the rock the permeability of the sandstone remained largely unaffected by intrusion

eof analysis and modeling of gps tec climatology over north america an empirical ionospheric model of the total electron content tec over north america 20 60 n 40 140 w is constructed using the gps tec data collected by massachusetts institute of technology mit haystack observatory during the years 2001 2012 this model is based on an analysis of quiet time monthly averages using the empirical orthogonal function eof decomposition technique allowing for separation of spatial and temporal variations the importance of different types of spatial temporal variations to the overall tec variability can be well represented by the characteristics of eof basis functions and associated principal components coefficients with various modes the mode one eof decomposition constitutes 97 5 of the total variance and therefore represents the essential feature of north america spatial and diurnal variation of the tec the mode two eof as reported in an earlier study reveals a large and significant symmetric longitudinal variation of the ionosphere organized with respect to magnetic declination the mode three eof decomposition shows midlatitude latitudinal structure that varies with season in a manner very similar to the so called winter anomaly because of the quick convergence of eof decomposition modes the first four eof modes are utilized for constructing a tec empirical model for each of the eof modes the temporal variations are expressed analytically in terms of local time season and solar activity and the spatial variations by cubic spline functions an analysis of accuracy and quality indicates that this regional empirical tec model can reflect the majority of the quiet time monthly means and represent characteristic temporal spatial variations in the north america

the geomagnetic storm time response of gps total electron content in the north american sector over the last two decades maps of gps total electron content tec have improved our understanding of the large perturbations in ionospheric electron density which occur during geomagnetic storms however previous regional and global studies of ionospheric storms have performed only a limited separation of storm time local time longitudinal and seasonal effects using 13 years of gps tec data we present a complete statistical characterization of the ionospheric response to geomagnetic storms for midlatitudes in the north american sector where dense ground receiver coverage is available the rapid onset of a positive phase is observed across much of the dayside and evening ionosphere followed by a longer lasting negative phase across all latitudes and local times our results show clear seasonal variations in the storm time tec such that summer events tend to be dominated by the negative storm response while winter events exhibit a stronger initial positive phase with minimal negative storm effects we find no discernable difference between spring and fall equinox events with both being equivalent to the average storm time response across all seasons we also identify a prominent magnetic declination effect such that stronger dayside positive storm effects are observed in regions of negative declination i e eastern north america on the nightside asymmetries in the tec response are observed near the auroral oval and midlatitude trough which may be attributed to thermospheric zonal winds pushing plasma upward downward along field lines of opposite declination

distinguishing magmatic and metamorphic processes in peralkaline rocks of the norra karr complex southern sweden using textural and compositional variations of clinopyroxene and eudialyte group minerals

east west differences in f region electron density at midlatitude evidence from the far east region the global configuration of the geomagnetic field shows that the maximum east west difference in geomagnetic declination of northern middle latitude lies in the us region similar to 32 degrees which produces the significant ionospheric east west coast difference in terms of total electron content first revealed by zhang et al 2011 for verification it is valuable to investigate this feature over the far east area which also shows significant geomagnetic declination east west gradient but smaller similar to 15 degrees than that of the us the current study provides evidence of the longitudinal change supporting the thermospheric zonal wind mechanism by examining the climatology of peak electron density nmf2 electron density ne of different altitudes in the far east regions with a longitude separation of up to 40 60 degrees based on ground ionosonde and space based measurements although the east west difference r ew over the far east area displays a clear diurnal variation similar to the us feature that is negative r ew west ne east ne in the noon and positive at evening night the observational results reveal more differences including 1 the noontime negative r ew is most pronounced in april june while in the us during february march thus for the late spring and summer period negative r ew over the far east region is more significant than that of the us 2 the positive r ew at night is much less evident than in the us especially without winter enhancement 3 the magnitude of negative r ew tends to enhance toward solar maximum while in the us showing anticorrelation with the solar activity the altitude distribution of pronounced negative difference 300 400 km moves upward as the solar flux increases and hence produces the different solar activity dependence at different altitude the result in the paper is not simply a comparison corresponding to the us results but raises some new features that are worth further studying and improve our current understanding of ionospheric longitude difference at midlatitude citation zhao b m wang y wang z ren x yue j zhu w wan b ning j liu and b xiong 2013 east west differences in f region electron density at midlatitude evidence from the far east region j geophys res space physics 118 542 553 doi 10 1029 2012ja018235

tertiary andean volcanism in a caldera graben setting the miocene farellones formation in central chile 32 35 s is one of several up to 3000 mthick tertiary volcanic sequences in the central andes with ash flows and intercalations of lacustrine sediments in their lower part and intermediate to basic lavas and rhyolitic domes in their upper part the farellones rocks were probably deposited in a volcano tectonic graben formed through a series of caldera collapses this is suggested by a the fact that the formation frequently is delimited by normal faults towards which the subhorizontal strata pinch out and become upraised indicating deposition during subsidence b the huge volume of erupted acid magma and c a high paleothermal gradient of geothermal field type similar tertiary volcanic sequences in northern chile and central peru probably also formed by eruptions in a caldera graben setting this setting and the geothermal field type of alteration make these sequences good prospecting targets for epithermal preciousmetal deposits

multi stage zeolite facies mineralization in the hvalfjordur area iceland the hvalfjordur area 30 km north of iceland s capital reykjavik belongs to the sequence of late tertiary to early quaternary flood basalts with minor intercalations of hyaloclastites and rhyolites the basalts are affected by progressive low temperature metamorphism caused by the burial of the lava succession and higher heat flow from nearby central volcanoes low grade zeolite facies metamorphism of basaltic lavas in the hvalfjordur area results in two distinct mineral parageneses that can be correlated to events in the burial and hydrothermal history of the lava pile stage ia represents syn eruptive near surface alteration in which celadonite and silica were precipitated along primary pores during regional burial metamorphism stage ib hydrolysis of olivine and glass led to the formation of mixed layer chlorite smectite clays the chlorite content of stage ib phyllosilicate vesicle rims increases with increasing burial depth and temperature stage ii occurred after the burial and is marked by zeolite mineralization caused by higher heat flow from the laxarvogur and hvalfjordur central volcanoes altogether 11 different zeolites were found in the hvalfjordur area analcime chabazite epistilbite heulandite laumontite levyne mesolite stilbite stellerite thomsonite and yugawaralite in total three separate depth and temperature controlled zeolite zones occur in the hvalfjordur area

a case study of the ionospheric storm dusk effect the initial ionospheric storm positive phase often appears as a large enhancement in f region electron density at middle latitudes in the evening hours following a storm sudden commencement the cause of this dusk effect is still not well understood though several mechanisms have been proposed this phenomenon is studied using incoherent scatter radar data collected at millstone hill and total electron content data from a north south chain of stations during the may 26 27 1990 storm nine position millstone hill radar data allows estimation of gradients in electron density and in velocity components above the station from these the motion term in the continuity equation is calculated and used along with wind electric field data and modeling to assess the relative importance of the proposed mechanisms during this storm it is shown that a combination of mechanisms appear to have been involved including a traveling atmospheric disturbance advection of high density plasma from lower latitudes and neutral composition changes

genesis of zeolites in the neapolitan yellow tuff geological volcanological and mineralogical evidence the study proposes a model by which a thick succession of volcanic tuffs can be zeolitized by alteration of pyroclastic material in the presence of sufficient eruptive water and at temperatures close to water vapour condensation in the case of phreatomagmatic products the model simplifies interpretation of problematic deposits that exhibit pronounced vertical and lateral variation in lithification grade a major feature of the model is that thick zeolitized tuffs can be formed during emplacement of pyroclastic products in marked contrast to later alteration in an open hydrologic system geological volcanological and mineralogical data for the neapolitan yellow tuff a widespread trachytic pyroclastic deposit outcropping around campi flegrei southern italy have been used to infer the physico chemical conditions that determined mineral genesis this tuff shows a reduction in lithification grade towards the base top and with distance from the vent and very variable zeolitization within the lithified portion we suggest that during initial emplacement the erupted products chilled against the ground inhibiting zeolite crystallization during rapid deposition of the thick wet succession thermal insulation allowed the persistence of elevated temperatures for a time sufficient for enhancement of hydration dissolution processes in the volcanic glass the highly reactive alkali trachytic glass quickly buffered the acid ph of the system favouring phillipsite crystallization followed by chabazite nucleation the variable zeolite content reflects fluctuating emplacement conditions e g changes in water content and temperature cooling of the upper and relatively thin distal deposits inhibited the zeolitization process thereby preserving the primary unlithified deposit

superdarn observations during geomagnetic storms geomagnetically active times and enhanced solar wind driving the super dual auroral radar network superdarn was built to study ionospheric convection at earth and has in recent years been expanded to lower latitudes to observe ionospheric flows over a larger latitude range this enables us to study extreme space weather events such as geomagnetic storms which are a global phenomenon on a large scale from the pole to magnetic latitudes of 40 we study the backscatter observations from the superdarn radars during all geomagnetic storm phases from the most recent solar cycle and compare them to other active times to understand radar backscatter and ionospheric convection characteristics during extreme conditions and to discern differences specific to geomagnetic storms and other geomagnetically active times we show that there are clear differences in the number of measurements the radars make the maximum flow speeds observed and the locations where they are observed during the initial main and recovery phase we show that these differences are linked to different levels of solar wind driving we also show that when studying ionospheric convection during geomagnetically active times it is crucial to consider data at midlatitudes as we find that during 19 of storm time the equatorward boundary of the convection is located below 50 of magnetic latitude

momentum balances on the north carolina inner shelf four months of moored current pressure temperature conductivity wave and wind observations on the north carolina shelf indicate three dynamically distinct regions the surf zone the inner shelf between the surf zone and the 13 m isobath and the midshelf in the surf zone the along shelf momentum balance is between the cross shelf gradient of the wave radiation stress and the bottom stress the linear drag coefficient in the surf zone is about 10 times larger than seaward of the surf zone on the inner shelf the along shelf momentum balance is also frictional the along shelf wind stress and pressure gradient are balanced by bottom stress in the cross shelf momentum balance the pressure gradient is the superposition of roughly equal contributions from the coriolis force geostrophy and wave setdown from shoaling unbroken surface gravity waves at midshelf the along shelf momentum balance is less frictional and hence flow accelerations are important the cross shelf momentum balance is predominantly geostrophic because the greater depth and smaller bottom slope at midshelf reduce the importance of wave setdown the cross shelf density gradient is in thermal wind balance with the vertical shear in the along shelf flow in depths as shallow as 10 m the dominant along shelf momentum balances provide a simple estimate of the depth averaged along shelf current in terms of the measured forcing i e wind stress wave radiation stress divergence and along shelf pressure gradient that reproduces accurately the observed cross shelf variation of the depth averaged along shelf current between the surf zone and midshelf

formation of zeolites in open hydrologic systems in contrast to those deposits formed by the alteration of volcanic ash in saline alkaline lakes discussed in the chapter by hay and sheppard this volume large volumes of tuffaceous sediments around the world have been transformed to zeolites and other authigenic silicate minerals by the action of percolating water in open hydrologic systems these include systems that have experienced significant chemical and hydrologic exchanges with the surrounding environment tephra sequences exposed to open system alteration commonly show a vertical zonation of zeolites and other authigenic minerals that reflects the chemical changes in meteoric water moving through the system flow in an open hydrologic system can either be downward or have a downward component where meteoric water enters the system resulting in a vertical or nearly vertical zonation of water composition and authigenic minerals the original pyroclastic materials of tuffaceous sediments may have been laid down in the sea close to the volcanic sources air laid onto the land surface or reworked into fluviatile and freshwater lacustrine environments open system zeolite deposits are most common in nonmarine rocks although many are known in sediments that were deposited in shallow marine environments zeolite deposits of the open system type are commonly several hundred meters thick and can be traced laterally for several tens of kilometers many examples of zeolite deposits that formed from land laid tephra have been recognized in the western united states but most of the large marine deposits are in japan and in southern and southeastern europe because of their relatively large and commonly discontinuous areal extent open system deposits have not been studied in as much detail as some other types of zeolite deposits in sedimentary rocks however studies of several key areas have provided a sound basis for the current understanding of this type of zeolite body zeolitic alteration can take place

metamorphic gradients in burial metamorphosed vesicular lavas comparison of basalt and spilite in cretaceous basic flows from central chile partial spilitization of a 9 km thick pile of flood basalts with highly vesicular flow tops gave rise to patterns of secondary mineralogy at different scales a a local pattern of mineralogical variation from the almost unaltered bottom towards the altered top of each flow and b an overall pattern comparing flow tops throughout the pile with changes in mineralogical composition within a sequence of metamorphic zones and facies the local patterns mimic the trend of the overall pattern but are of opposite direction and telescoped thus a gradual ordering and andepletion of the secondary albite and increases in the fe al ratio of epidote and pumpellyite upwards within individual flows are comparable in range to corresponding overall changes downwards throughout several kilometres the mineralogical changes within the flows diminish in range towards the more altered deeper part of the pile

hydrogeologic control on zeolitic diagenesis of the white river sequence smectite opal ct and clinoptilolite are common alteration products in the white river sequence a mid tertiary unit in the great plains and northern rocky mountains the white river sequence is largely made up of fine grained tuffaceous material that is rich in unaltered rhyolitic glass smectite is ubiquitous and it or a precursor phase was present during white river soil formation but also formed after burial smectite fe from 5 to 7 fe 2 o 3 and ti from 0 4 to 0 8 tio 2 concentrations in mud rocks suggest formation from dacitic to latitic glass rhyotitic glass however was the primary source for opal ct and clinoptilolite opal ct and clinoptilolite have a highly variable distribution over macroscopic to regional scales of observation stable isotopic compositions of smectite 18 o smow 11 8 to 13 3 opal ct 18 o smow 19 9 to 24 3 and late diagenetic calcite 18 o smow 10 3 2 0 suggest that burial diagenetic reactions took place at temperatures ranging from 27 to 55 c clinoptilolite apparently formed in areas with high contact times between paleoground water and vitroclastic material in white river rocks of wyoming clinoptilolite occurs only in localities that are interpreted as lying within paleo ground water discharge zones in the great plains clinoptilolite is rare in eastern colorado and southern nebraska but progressively increases in abundance to the north reflecting a northward decrease in permeability zeolitic alteration near douglas wyoming changed the hydrologic role of tuffs from aquifers to aquitards tuffs were originally aquifers because of their high permeability 30 md relative to interbedded mud rocks 10 4 to 1 md signigicant thicknesses 0 5 to 2 m presentday and lateral continuity tuff alteration however decreased permeability by 4 orders of magnitude relative to glass rich portions similar diagenetic effects on mud rock permeabilities are likely mass flux into altered tuffs at douglas is indicated by an increase in bulk rock density from 1 3 g cm 3 for glass rich tuff to 1 7 and 2 0 g cm 3 respectively for zeolitic and siliceous counterparts local silica redistribution accouts for the bulk of the density increases a systematic increase in ba content of clinoptilolite over a 150 m vertical section from 0 1 to 6 6 mol of the exchangeable cations suggests that it was derived from underlying units

geothermal type alteration in a burial metamorphosed volcanic pile central chile the upper cretaceous and tertiary volcanic sequences in the chilean andes are affected by burial metamorphism for example in central chile between 32 30 and 35 s the abanico formation a folded upper cretaceous to palaeogene unit composed of basic lavas tuffs and ash flows of intermediate composition and volcaniclastic sandstones is characterized by heulandite to laumontite bearing zeolite facies assemblages in its upper part passing with depth to prehnite pumpellyite facies assemblages however at c 33 30 s in the abanico hill area located just east of a graben at santiago the longitudinal central valley the alteration pattern is unrelated to stratigraphic depth it is characterized by a lateral increase in grade defined by assemblages with yugawaralite reported for the first time in the andes laumontite then wairakite epidote and finally with abundant epidote successively closer to the graben boundary this pattern was formed in a palaeogeothermal system with a high t and a very low p gradient geothermal alteration has also been inferred from the border zone of a neogene caldera in the abanico hill area and from the western fault boundary of the graben these expressions of geothermal alteration together with the occurrence of caldera structures the huge volume of ignimbrites and numerous epithermal precious metal deposits of late cretaceous and tertiary age in central and northern chile suggest that fossil geothermal systems of this age are probably common features in the chilean andes

magnetic declination and zonal wind effects on longitudinal differences of ionospheric electron density at midlatitudes 1 a prominent ionospheric longitudinal variation at midlatitudes in particular over the continental us was found recently this variation is characterized as a higher east side electron density in the evening and a higher west side electron density in the morning and with clear seasonal and solar activity dependencies a combined effect of geomagnetic declination and changing zonal winds was proposed to explain it this paper represents a comprehensive investigation of this effect by examining climatology for both electron density longitudinal differences and the nighttime zonal winds in the eastern us electron density is from incoherent scatter radar extra wide coverage experiments during 1978 2011 over millstone hill for which the spatial separation of the data can be up to 50 in longitude the thermospheric zonal wind is from the on site fabry perot interferometer measurements during 1989 2001 the observed zonal wind climatology is found to be perfectly consistent with the expectation based on the east west electron density differences in terms of local time seasonal and solar cycle dependencies the correlation between the zonal wind and the east west differential ratio is extremely high with an overall correlation coefficient of 0 93 the observed time delay of 3 hours in the response of electron density differences to zonal winds is a marked feature thus these results confirm positively the declination zonal wind mechanism and provide new insight into longitudinal variations at midlatitudes for other geographic sectors

alteration history of mount epomeo green tuff and a related polymictic breccia ischia island italy evidence for debris avalanche this paper presents mineralogical chemical and textural data for the mount epomeo green tuff and an associated polymictic breccia on ischia island italy with the purpose of defining the alteration history of the two units and the emplacement origin of the polymictic breccia our results indicate that the green tuff trachytic ignimbrite experienced three alteration events that produced the following mineral assemblages 1 phillipsite randomly interstratified r0 illite smectite i s fe illite and smectite in situ green tuff 2 chabazite phillipsite r0 i s and fe illite proximal facies green tuff at scarrupata di barano and 3 analcime authigenic k feldspar fe illite r0 i s and smectite clasts of green tuff in polymictic breccia phillipsite chabazite and r0 i s within the in situ and proximal facies green tuff indicate low temperature alteration t 70 c alteration within a mostly closed chemical system these data suggest that the polymictic breccia represents a debris avalanche deposit created by a catastrophic volcanic collapse which was associated with low temperature hydrothermal alteration and thus structural weakening of the volcano the debris avalanche that produced the polymictic breccia on ischia may be related to nearby massive debris avalanche deposits recently discovered offshore of southern ischia the young age of the polymictic breccia 5 7 8 6 ka and the possibility of its catastrophic emplacement indicate an additional volcanic hazard for ischia island

alteration and burial dolomitization of fine grained intermediate volcaniclastic rocks under saline alkaline conditions bayindulan sag in the er lian basin china abstract a novel type of burial dolomitization related to alteration of intermediate volcaniclastic rocks is discussed based on mineralogical petrological and geochemical analyses lacustrine fine grained

direct measurements of wind stress over the surf zone field data of the wind stress over surf zone waves are presented from an open ocean beach on the east australian coast two ultrasonic anemometers were deployed at nominal heights of 5 and 10 m above the water surface in the intertidal and inner surf zones with concurrent measurements of water levels and offshore wave parameters following a rigorous quality control procedure the wind stress was determined by the eddy correlation technique a constant stress layer was observed between 5 and 10 m elevation considering near neutral conditions only the wind drag coefficients were found to systematically change with the wind angle of approach relative to the shoreline and are much smaller for longshore wind than during onshore wind the concept of an apparent wave steepness changing with wind direction is suggested to explain this behavior the drag coefficients over the surf zone during onshore wind and near neutral conditions were determined to be almost twice the values expected at the same wind speed and open ocean conditions the observed charnock coefficient was similarly an order of magnitude larger than open ocean values a wave celerity of the order of that expected in the inner surf zone is required to explain the observed large roughness and drag coefficients using existing wave age dependent parameterizations this suggests that the slower wave celerity in the surf zone is an important contributor to the increased wind stress in addition to the sawtooth wave shape key points a new field data set of the wind stress over surf zone waves is presented concept of an apparent wave steepness is proposed to explain drag observations surf zone drag coefficients were almost twice the values outside the surf

hydrothermal alteration and zeolitization of the fohberg phonolite kaiserstuhl volcanic complex germany the subvolcanic fohberg phonolite kaiserstuhl volcanic complex germany is an economic zeolite deposit formed by hydrothermal alteration of primary magmatic minerals it is mined due to the high 40 wt zeolite content which accounts for the remarkable zeolitic physicochemical properties of the ground rock new mineralogical and geochemical studies are carried out a to evaluate the manifestation of hydrothermal alteration and b to constrain the physical and chemical properties of the fluids which promoted hydrothermal replacement the alkaline intrusion is characterized by the primary mineralogy feldspathoid minerals k feldspar aegirine augite wollastonite and andradite the rare earth elements phase gotzenite is formed during the late stage magmatic crystallization fluid induced re equilibration of feldspathoid minerals and wollastonite caused breakdown to a set of secondary phases feldspathoid minerals are totally replaced by various zeolite species calcite and barite wollastonite breakdown results in the formation of various zeolites calcite pectolite sepiolite and quartz zeolites are formed during subsolidus hydrothermal alteration 150 c under alkaline conditions a sequence of ca na dominated zeolite species gonnardite thomsonite mesolite is followed by natrolite the sequence reflects an increase in log a text na a text h and decrease in log a text ca 2 a text h 2 of the precipitating fluid low radiogenic 87sr 86sr values indicate a local origin of the elements necessary for secondary mineral formation from primary igneous phases in addition fractures cut the intrusive body which contain zeolites followed by calcite and a variety of other silicates carbonates and sulfates as younger generations stable isotope analysis of late fracture calcite indicates very late circulation of meteoric fluids and mobilization of organic matter from surrounding sedimentary units

multiradar observations of the polar tongue of ionization 1 we present a global view of large scale ionospheric disturbances during the main phase of a major geomagnetic storm we find that the low latitude auroral and polar latitude regions are coupled by processes that redistribute thermal plasma throughout the system for the large geomagnetic storm on 20 november 2003 we examine data from the high latitude incoherent scatter radars at millstone hill sondrestrom and eiscat tromso with superdarn hf radar observations of the high latitude convection pattern and dmsp observations of in situ plasma parameters in the topside ionosphere we combine these with north polar maps of stormtime plumes of enhanced total electron content tec derived from a network of gps receivers the polar tongue of ionization toi is seen to be a continuous stream of dense cold plasma entrained in the global convection pattern the dayside source of the toi is the plume of storm enhanced density sed transported from low latitudes in the postnoon sector by the subauroral disturbance electric field convection carries this material through the dayside cusp and across the polar cap to the nightside where the auroral f region is significantly enhanced by the sed material the three incoherent scatter radars provided full altitude profiles of plasma density temperatures and vertical velocity as the toi plume crossed their different positions under the cusp in the center of the polar cap and at the midnight oval polar cap boundary greatly elevated f peak density 1 5e12 m 3 and low electron and ion temperatures 2500 k at the f peak altitude characterize the sed toi plasma observed at all points along its high latitude trajectory for this event sed toi f region tec 150 1000 km was 50 tecu both in the cusp and in the center of the polar cap large upward directed fluxes of o 1 e14 m 2 s 1 were observed in the topside ionosphere

occurrence composition and origin of analcime in sedimentary rocks of non marine petroliferous basins in china abstract natural analcime a highly brittle aluminosilicate mineral that dissolves easily during diagenesis occurs in the sedimentary rocks of eight main non marine petroliferous basins in china this mineral has been well documented for the past 30 years and has proved to be significant for the formation of high quality hydrocarbon reservoirs the present study fully reviews analcime occurrences chemical compositions si al ratios origin and controlling factors and influence on the hydrocarbon reservoir quality in permian to paleogene sedimentary rocks previous research has shown that analcime is commonly distributed within argillaceous laminae l type occurs as intergranular cement c type replacement r type and crack filling f type forms or is closely intergrown with other authigenic exhalative minerals a type analcime in lacustrine basins is slightly al rich and na poor and its si al ratios range from 1 95 to 2 80 the geochemical compositions of the analcime and ankerite bearing exhalites are characterised by enrichment in light rare earth elements and 13c and depletion in heavy rare earth elements and 18o with negative eu and positive ce anomalies diagenetic analcime forms by the alteration of volcanic glass clays or zeolite precursors in saline alkaline lakes or during buried diagenetic stages in sedimentary rocks in addition it coexists with other authigenic zeolite carbonate and clay minerals as well as albite hydrothermal analcime presumably precipitates from hydrothermal fluids and is not dependent on a local precursor mineral or volcanic glass this type is commonly related to exhalative mineralisation of hydrothermal springs the formation of natural analcime is controlled by various factors such as the composition of the parent material temperature prevalent during crystallisation chemistry of the fluid phase and thermodynamic characteristics of the geological environment as zeolites are formed in alkaline fluid phases they become unstable in acidic pore water secondary pores created by analcime mineral dissolution and intercrystalline micropores among analcime minerals are highly significant in hydrocarbon reservoirs analcime bearing mudstone siltstone dolostone and exhalite are favourable lithofacies for unconventional hydrocarbon accumulation owing to its high brittleness and selective dissolution of analcime and other associated minerals

miocene fossil hydrothermal system associated with a volcanic complex in the andes of central chile abstract cenozoic deposits in the andes of central chile have been affected by very low grade burial metamorphism at about 33 s in the cuesta de chacabuco area approximately 53 km north of santiago two oligocene and miocene volcanic units form a ca 1300 m thick rock pile the miocene unit corresponds to a volcanic complex composed of two eroded stratovolcanoes secondary mineral assemblages in both units were studied petrographically and using x ray diffraction and electron microprobe analyses most of the igneous minerals are wholly or partially preserved and the ubiquitous secondary minerals are zeolites and mafic phyllosilicates the alteration pattern observed is characterized by a lateral zonation in secondary mineralogy related to a lateral increase in temperature but not to stratigraphic depth the following three zones were established mainly based on the distribution of zeolites zone i comprises heulandite thomsonite mesolite stilbite and tri smectite zone ii contains laumontite yugawaralite prehnite epidote and chlorite and zone iii comprises wairakite epidote chlorite diopside biotite and titanite for each zone the following temperature ranges were estimated zone i 100 180 c zone ii 180 270 c and zone iii 245 310 c the alteration episode was characterized by a high p fluid p total ratio ca 1 0 although slightly variable a high geothermal gradient of ca 160 c km 1 and fluid pressures below 500 bars although temperature was the main control on the mineral zonation several interrelated parameters mainly fluid composition porosity and permeability were also important hot near neutral to slightly alkaline ph alkali chloride hydrothermal fluids with very low dissolved co 2 contents deposited the secondary minerals the alteration pattern is the result of depositing fluids in outflow regions from a hydrothermal system developed inside a volcanic complex during the miocene the hydrothermal system has been eroded to a maximum depth of 1 7 km

volcaniclastic rocks of the reydarfjordur drill hole eastern iceland 2 alteration volcaniclastic rocks of basaltic to rhyolitic composition interlayered with basaltic to icelanditic lava flows in a 1918 m drill hole in eastern iceland are altered to zeolite and pumpellyite prehnite facies assemblages major alteration minerals are chlorites illite chlorite mixed minerals illites k feldspar laumontite quartz and sphene others include julgoldite and secondary allanite smectites as well as mordenite and heulandite are restricted to the upper 900 m epidote and minor pumpellyite prehnite wairakite and anhydrite are restricted to the core below 900 m the boundary between zeolite and prehnite pumpellyite facies is marked by the appearance of chlorite epidote quartz assemblages at around 900 m the typical paragenesis prehnite pumpellyite epidote chlorite occurs near the base of the drill hole at 1855 m textures indicate generally prograde metamorphic conditions the broad compositional spectrum ranging from basalt to rhyolite abundance of vitric fragments and high initial porosity and permeability of the volcaniclastic rocks were major factors governing alteration the site of growth crystal shard vesicle pore and vein of a secondary phase strongly influences composition habit amount paragenesis and time of crystallization for example sphene and to a lesser degree epidote are less rich in fe and better crystallized in plagioclase than in the adjacent matrix the different mineral assemblages developed within plagioclase crystals through the section most clearly reflect the metamorphic changes the abundance of vitric rhyolitic clasts shards and pumice favored k al si enriched fluids from which phases like illite and adularia crystallized these phases were not found in interlayered basalt flows mehegan et al this issue low ca activity is also indicated by the occurrence of wairakite and pumpellyite rather than prehnite which is common in the basalts secular changes during metamorphism in pore fluid composition are shown by zonations in mineral compositions for example the depletion of epidote and juldoldite pumpellyite in fe with time appears to reflect decreasing o2 bulk rock chemical changes are more intense in the volcaniclastic rocks compared to the basalt lavas h2o fe3 fe2 and in part co2 values are higher in the upper part of the hole reflecting the higher porosity and glass content of the clastic rocks they decrease markedly downhole approaching values of the lava flows due to more pervasive metamorphic alteration and thus similar mineral assemblages and physical properties

low grade metamorphism and geotectonic setting of the macuchi formation western cordillera of ecuador the cretaceous eocene basic to intermediate marine volcanic rocks of the mucuchi formation constitute the western cordillera in northern ecuador their chemical features mostly correspond to those of tholeiitic basalts with some calc alkaline affinities and suggest an oceanic island arc setting the macuchi rocks are affected by low grade non deformative metamorphism characterized by zeolite prehnite pumpellyite and lower greenschist facies assemblages depth zonation is suggested by the downward mineral sequence i laumontite pistacitic epidote pumpellyite prehnite ii pumpellyite prehnite pistacitic epidote iii actinolite biotite pistacitic epidote chlorite this broad zonation and the chemistry of individual minerals point to an interaction between the volcanic rocks and sea water under a moderate to high thermal gradient 75 c km alteration appears to have been dependent primarily on fluid control volume pressure composition temperature and reaction kinetics which together partly overshadow the role of load pressure compositional variations of a mineral species at the scale of a contiguous flow or even at the scale of a thin section show that intensity of alteration was spatially uneven depending on rock permeability and consequently metastable equilibrium commonly exists however a progressive approximation to equilibrium as a result of p t control is shown by the mineralogy a high fo2 of the fluid phase is evident from the mineral chemistry the metamorphism of the macuchi volcanics is similar to the hydrothermal burial type produced during the development of a volcanic arc where lavas and volcanoclastics accumulated in a shallow marine environment however some of its characteristics point to a transition toward systems defined by a higher t p ratio such as those found in ocean floor metamorphism a model is proposed in which the macuchi volcanics are assigned to an oceanic island arc generated contemporaneously with a marginal basin which has opened as the outcome of progressive north south attenuation of the continental crust due to mantle diapirism

mineral processing characteristics of natural zeolites from the aritayn formation of northeast jordan the inferior grade of natural zeolite ores in comparison to their synthetic counterparts has been identified as a possible factor responsible for the relatively small market share of the former this paper describes the results of laboratory scale mineral processing trials carried out on relatively low grade natural zeolite ores from the aritayn formation of northeast jordan to improve their purity through removal of unwanted gangue constituents appropriate sample preparation and mineral processing methods were selected which utilised contrasts in texture particle size hardness specific gravity and magnetic susceptibility between gangue and target constituents to achieve beneficiation sample preparation by autogenous comminution was able to selectively liberate zeolite minerals from the surface of pyroclasts and therefore was an effective method of pre concentration subsequently using widely available magnetic and gravity separation equipment a high grade concentrate containing 89 zeolite was produced at a recovery of 37 from a lapilli tuff of 47 head grade

use of zeolitic tuff in the building industry zeolite rich volcanic tuffs are widely distributed in almost every country of the world where they are present in low medium or high grade million ton deposits even though the formation of the zeolite minerals may have followed different genetic paths the zeolitic rocks have in common a matrix of finely crystalline zeolite that cements the other nonzeolitic particles and is responsible for the overall mechanical properties of the material zeolitic tuffs have been employed since pre historic times in construction mostly as dimension stone this use is still the most common of natural zeolites in the building industry although other applications have recently come to the forefront such as lightweight aggregate or as additives for manufacturing blended cements given the fact that much of this material is excavated and used locally and that the market demand is strongly affected by the trends of the building industry estimates of the worldwide zeolitic tuff production for construction purposes are difficult to make in italy where the use of zeolitic tuff as dimension stone is commonplace about 75 quarries were reported in operation in 1992 with total production of about 3 x 106 tons per year aiello 1995 more recently this production has decreased due to the crisis of the building industry and in 1998 it amounted to about 1 5 106 tons per year in japan the production of tuff as dimension stone is currently about 4 105 tons per year n kuchitsu national research institute of cultural properties tokyo japan pers comm 1996 considering that zeolitic tuff is used as dimension stone in many other countries as well e g bulgaria cuba germany greece hungary mexico romania and turkey the current worldwide zeolitic tuff consumption as dimension stone is about 3 106 tons per year information is even more

revised crism spectral parameters and summary products based on the currently detected mineral diversity on mars the investigation of hyperspectral data from the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism and the observatoire pour la mineralogie l eau les glaces et l activitie omega on mars express has revealed an increasingly diverse suite of minerals present on the martian surface a revised set of 60 spectral parameters derived from corrected spectral reflectance at key wavelengths in crism targeted observations and designed to capture the known diversity of surface mineralogy on mars is presented here as summary products some of the summary products have strong heritage to omega spectral parameter calculations this paper also presents newly derived parameters that highlight locations with more recently discovered spectral signatures type locations for the diversity of currently identified mineral spectral signatures have been compiled into a library presented in this work our analysis indicates that the revised set of summary products captures the known spectral diversity of the surface and successfully highlights and differentiates between locations with differing spectral signatures the revised spectral parameter calculations and related products provide a useful tool for scientific interpretation and for future mission landing site selection and operations

direct observations of the role of convection electric field in the formation of a polar tongue of ionization from storm enhanced density 1 we examine the relationship of convection electric fields to the formation of a polar cap tongue of ionization toi from midlatitude plumes of storm enhanced density sed observations from the geomagnetic storm on 26 27 september 2011 are presented for two distinct sed events during an hour long period of geomagnetic activity driven by a coronal mass ejection a channel of high density f region plasma was transported from the dayside subauroral ionosphere and into the polar cap by enhanced convection electric fields extending to middle latitudes this toi feature was associated with enhanced hf backscatter indicating that it was the seat of active formation of small scale irregularities after the solar wind interplanetary magnetic field conditions quieted and the dayside convection electric fields retreated to higher latitudes an sed plume was observed extending to but not entering the dayside cusp region this prominent feature in the distribution of total electron content tec persisted for several hours and elongated in magnetic local time with the rotation of the earth no ionospheric scatter from superdarn radars was observed within this sed region the source mechanism enhanced electric fields previously drawing the plasma from midlatitudes and into the polar cap as a toi was no longer active resulting in a fossil feature we thus demonstrate the controlling role exercised by the convection electric field in generating a toi from midlatitude sed

the dependence of sea surface roughness on the height and steepness of the waves it is proposed that the sea surface roughness zo can be predicted from the height and steepness of the waves zo hs a hs lp b where hs and lp are the significant wave height and peak wavelength for the combined sea and swell spectrum best estimates for the coefficients are a 1200 b 4 5 the proposed formula is shown to predict well the magnitude and behavior of the drag coefficient as observed in wave tanks lakes and the open ocean thus reconciling observations that previously had appeared disparate indeed the formula suggests that changes in roughness due to limited duration or fetch are of order 10 or less thus all deep water pure windseas regardless of fetch or duration extract momentum from the air at a rate similar to that predicted for a fully developed sea this is confirmed using published field data for a wide range of conditions over lakes and coastal seas only for field data corresponding to extremely young waves u10 cp 3 were there appreciable differences between the predicted and observed roughness values the latter being larger on average significant changes in roughness may be caused by shoaling or by swell a large increase in roughness is predicted for shoaling waves if the depth is less than about 0 2lp the presence of swell in the open ocean acts on average to significantly decrease the effective wave steepness and hence the mean roughness compared to that for a pure windsea thus the predicted open ocean roughness is at most wind speeds significantly less than is observed for pure wind waves on lakes only at high wind speeds such that the windsea dominates the swell do the mean open ocean values reach those for a fully developed sea

the occurrence of ionospheric signatures of plasmaspheric plumes over different longitudinal sectors 1 plasmaspheric plumes have ionospheric signatures and are observed as storm enhanced density sed in global positioning system gps total electron content tec these ionospheric signatures have been primarily observed over the american sector and in a few limited examples over the european sector this study examines the longitudinal occurrence frequency of plasmaspheric plumes we analyzed all images from the imager for magnetopause to aurora global exploration image extreme ultraviolet imager euv databases for the first half of 2001 and identified a total of 31 distinct plume intervals observed during different storm events out of the total image euv plumes that we identified 12 were projected over north america 10 over asia and the remaining 9 were over europe and the atlantic ocean using ground based gps tec from mit s madrigal database we searched for corresponding sed tec plumes at different longitudinal sector and found 12 ionospheric sed plume signatures over north america 4 over europe and 2 over asia this indicates that the observation probability of an ionospheric sed plume when a plasmaspheric plume is seen is 100 in the american sector 50 in the european sector and 20 in the asian sector this could be due to the fact that the plumes may be either positioned beyond the limit of the ground based gps field of view which happens mainly when there is less plasmaspheric erosion or are too weak to be detected by the sparse number of gps receivers over asia the in situ plasma densities from the available coincident defense metrological satellite program dmsp satellites were also used to study the characteristics of sed tec plume at dmsp orbiting altitude i e 870 km the topographic explorer topex altimeter tec also is used to identify the conjugate sed plume signature over the southern hemisphere

stepwise climate change recorded in eocene oligocene paleosol sequences from central oregon successions of paleosols bounded by erosional surfaces in fluvial sediments of the eocene oligocene strata of central oregon can be interpreted as terrestrial equivalents of the unconformity bound units of sequence stratigraphy in the upper part of the upper eocene clarno formation and in the lower part of the lower eocene lower miocene john day formation truncation surfaces separate otherwise conformable alluvial deposits and allow for stratigraphic subdivision into informal members lower and upper red hill claystones in the clarno formation and lower middle and upper big basin members and lower turtle cove member in the john day formation paleosols in each member show a stepwise change in the degree of weathering of the most strongly developed paleosols kaolinite rich ultisollike paleosols in lower red hill claystones late eocene 42 43 ma smectite rich alfisol like paleosols in the upper red hill claystones late eocene 41 42 ma alfisols and ultisol like paleosols in the lower big

a dayside ionospheric positive storm phase driven by neutral winds 1 this paper presents observations and numerical simulations of ionospheric and thermospheric disturbances associated with a moderate geomagnetic storm on 10 september 2005 during the event the incoherent radars located in millstone hill and arecibo observed a dayside positive storm phase as manifested by the enhanced electron density in the f region the universal time ut altitude profile of electron density measured by both radars displayed a structure that closely resembles the greek letter a similar structure is also reproduced by the thermosphere ionosphere electrodynamics general circulation model tiegcm this peculiar electron density distribution is found to be associated with vertical ion drift which initially was upward and then became downward using realistic time dependent ionospheric convection and auroral precipitation as inputs the tiegcm reveals that the primary cause of the positive storm response was the enhanced meridional neutral wind rather than the penetration magnetospheric electric field this study reiterates the importance of neutral wind effects on ionospheric disturbance

dimensionally consistent similarity relation of ocean surface friction coefficient in mixed seas abstractapplying wavelength scaling dimensionally consistent expressions of the ocean surface friction coefficient can be developed for both wind sea and mixed sea in the ocean for a wind sea with a monopeak wave spectrum the natural choice of the scaling wavelength is that of the spectral peak component for a mixed sea with a multipeak spectrum the peak component in the wind sea portion of the wave spectrum is not a good reference wavelength a much better scaling wavelength is the weighted average of swell and wind sea following the consideration of equivalent momentum in the wave field the resulting friction coefficient c 2 is referenced to the wind speed at one half of the scaling wavelength u 2 instead of c10 referenced to the neutral wind speed at 10 m elevation u10 although referencing the wind speed at a fixed elevation such as u10 is of practical necessity u 2 is physically significant as the free stream velocity in wave modulated boundary layer flows a simple procedure to apply the s

effects of disturbed electric fields in the low latitude and equatorial ionosphere during the 2015 st patrick s day storm the 2015 st patrick s day geomagnetic storm with sym h value of 233 nt is an extreme space weather event in the current 24th solar cycle in this work we investigated the main mechanisms of the profound ionospheric disturbances over equatorial and low latitudes in the asian australian sector and the american sector during this super storm event the results reveal that the disturbed electric fields which comprise penetration electric fields pefs and disturbance dynamo electric fields ddefs play a decisive role in the ionospheric storm effects in low latitude and equatorial regions pefs occur on march 17 in both the american sector and the asian australian sector the effects of ddefs are also remarkable in the two longitudinal sectors both the ddefs and pefs show the notable local time dependence which causes the sector differences in the characteristics of the disturbed electric fields this differences would further lead to the sector differences in the low latitude ionospheric response during this storm the negative storm effects caused by the long duration ddefs are intense over the asian australian sector while the repeated elevations of hmf2 and the eia intensifications caused by the multiple strong pefs are more distinctive over the american sector especially the storm time f3 layer features are caught on march 17 in the american equatorial region proving the effects of the multiple strong eastward pefs

altitude adjusted corrected geomagnetic coordinates definition and functional approximations analysis of the functional approximations used to transform between geo graphic and altitude adjusted corrected geomagnetic aacgm coordinates reveals that errors of 50 km can occur in the auroral and polar regions these errors are the result of efforts to better approximate aacgm coordinates near the magnetic equator and the south atlantic anomaly in these regions aacgm coordinates are not defined and alternate coordinates have been used this augmentation and emphasis on the so lution in regions near the equator result in spherical harmonic approximating functions that are less accurate than need be in the auroral and polar regions in response a new set of spherical harmonic coefficients have been derived that better represent aacgm coordinates in these regions these new aacgm coefficients are limited to below 2000 km in altitude in order to ensure accuracy for altitudes above 2000 km a magnetic field line tracing solution is recommended a software package developed to take advantage of the new aacgm coefficients provides the capability of tracing magnetic field lines at any altitude for improved accuracy in addition linear interpolation between 5 year epochs is used to produce coordinates that vary smoothly over the entire period from 1965 present the intent of this work is to provide a more accurate procedure for de termining aacgm coordinates in the auroral and polar regions for the study of mag netospheric and ionospheric processes

transition from the zeolite to prehnite pumpellyite facies in the karmutsen metabasites vancouver island british columbia

vertical flow structure during sandy duck observations and modeling abstract observations of the vertical distribution of time averaged cross shore and alongshore flows during the sandy duck field experiment are compared with model predictions to assess the parameters governing the flow behaviour the measurements were obtained with a vertical stack of eight two component current meters with the lowest and highest sensor at respectively o 0 1 and o 2 7 m above the bed observations under breaking wave conditions within the surfzone show that the maximum return flow velocities occur in the lower part of the water column consistent with laboratory observations under non breaking conditions outside the surfzone the maximum return flow velocities are observed closer to the water surface again in line with laboratory results analogous to previous observations the measured longshore current velocity profiles are logarithmic under non breaking conditions and become more depth uniform under breaking conditions the model description of the vertical structure of the flow includes the presence of wind stresses wave stresses pressure gradients turbulent eddy viscosity and a wave boundary layer the model utilizes parabolic shape functions to describe the vertical distribution of the turbulent eddy viscosity in the middle layer and within the bottom boundary layer eddy viscosity is enhanced in regions where turbulence is produced i e near the surface in the case of breaking waves and within the bottom boundary layer estimates of the wave breaking induced turbulent eddy viscosity and bottom friction are obtained by minimizing the model measurement discrepancies predictions utilizing calibrated expressions for both the turbulent eddy viscosity and bottom friction are in general agreement with the observations provided the wave transformation and associated mass flux are modeled correctly and a parabolic eddy viscosity distribution is used using a piecewise constant eddy viscosity distribution generally results in a degrading of the agreement between measurements and model results

the authigenic zeolites of the aritayn volcaniclastic formation north east jordan in the aritayn volcaniclastic formation the formation of zeolites is associated with the transformation of sideromelane into palagonite by reaction with percolating water in an open hydrological system three vertical zones are described characterised by fresh sideromelane at the top zone 1 palagonite smectite in the middle zone 2 and zeolites at the bottom zone 3 within zone 3 a phillipsite chabazite sub zone overlies a faujasite phillipsite sub zone the paragenetic sequence fresh sideromelane palagonite smectites saponite montmorillonite faujasite phillipsite chabazite natrolite calcite resembles those described in the literature except for the early formation of smectites in the jordanian occurrences faujasite is more abundant in these zeolitic tuffs than at any other locality in the world that has yet been described and the tuffs are considered to have excellent potential for beneficiation

alteration processes of the roque nublo ignimbrites gran canaria canary islands abstract the non welded lithic rich ignimbrites of roque nublo are the most characteristic deposits of the second magmatic cycle pliocene in age on gran canaria they are very heterogeneous with 35 55 by volume of lithic clasts 15 30 of moderately vesiculated pumice 5 7 of crystals and 20 30 of ash matrix the juvenile components pumice fragments and ash matrix are largely altered the mineral assemblage that originated by the alteration of vitric components consists mainly of zeolites chabazite phillipsite and analcime and subordinate smectites the alteration does not show any lateral or vertical gradation in the deposits and does not change in intensity with respect to the distance from the emission center these alteration processes affect only the roque nublo ignimbrites their associated fall and surge deposits remain unaltered a geo autoclave mechanism is proposed to explain the alteration processes which devitrified the juvenile components of the roque nublo ignimbrites and gave the rocks their characteristic strong induration this implies that the eruptions which led to the formation of the roque nublo ignimbrites had an important phreatomagmatic component and that the resulting pyroclastic flows were too dense and too poorly expanded to permit the water vapour to be separated from the vitric fragments during transport the alteration took place in situ and immediately after the deposition of the deposits when they were still hot by the reaction between the vitric components and the condensed vapour and cannot be attributed to late diagenesis or weathering

concentrated perchlorate at the mars phoenix landing site evidence for thin film liquid water on mars 1 nasa s phoenix mission which landed on the northern plains of mars in 2008 returned evidence of the perchlorate anion distributed evenly throughout the soil column at the landing site here we use spectral data from phoenix s surface stereo imager to map the distribution of perchlorate salts at the phoenix landing site and find that perchlorate salt has been locally concentrated into subsurface patches similar to salt patches that result from aqueous dissolution and redistribution on earth we propose that thin films of liquid water are responsible for translocating perchlorate from the surface to the subsurface and for concentrating it in patches the thin films are interpreted to result from melting of minor ice covers related to seasonal and long term obliquity cycles

phillipsite and al tobermorite mineral cements produced through low temperature water rock reactions in roman marine concrete author s jackson md mulcahy sr chen h li y li q cappelletti p wenk hr abstract 2017 by walter de gruyter berlin boston pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabric and durability of 2000 year old roman harbor concrete pliny the elder however in first century ce emphasized rock like cementitious processes involving volcanic ash pulvis that as soon as it comes into contact with the waves of the sea and is submerged becomes a single stone mass fierem unum lapidem impregnable to the waves and every day stronger naturalis historia 35 166 pozzolanic crystallization of al tobermorite a rare hydrothermal calcium silicate hydrate mineral with cation exchange capabilities has been previously recognized in relict lime clasts of the concrete synchrotron based x ray microdiffraction maps of cementitious microstructures in baianus sinus and portus neronis submarine breakwaters and a portus cosanus subaerial pier now reveal that al tobermorite also occurs in the leached perimeters of feldspar fragments zeolitized pumice vesicles and in situ phillipsite fabrics in relict pores production of alkaline pore fluids through dissolution precipitation cation exchange and or carbonation reactions with campi flegrei ash components similar to processes in altered trachytic and basaltic tuffs created multiple pathways to post pozzolanic phillipsite and al tobermorite crystallization at ambient seawater and surface temperatures long term chemical resilience of the concrete evidently relied on water rock interactions as pliny the elder inferred raman spectroscopic analyses of baianus sinus al tobermorite in diverse microstructural environments indicate a cross linked structure with al3 substitution for si4 in q3 tetrahedral sites and suggest coupled al3 na substitution and potential for cation exchange the mineral fabrics provide a geoarchaeological prototype for developing cementitious processes through low temperature rock fluid interactions subsequent to an initial phase of reaction with lime that defines the activity of natural pozzolans these processes have relevance to carbonation reactions in storage reservoirs for co2 in pyroclastic rocks production of alkali activated mineral cements in maritime concretes and regenerative cementitious resilience in waste encapsulations using natural volcanic pozzolans

low grade regional metamorphism in the mesozoic cenozoic volcanic sequences of the central andes all the mesozoic and cenozoic volcanic rocks of the central andes from southern ecuador to central chile except recent ones have been affected by episodes of regional metamorphism without change in texture and structure the metamorphism which ranges from low zeolite to greenschist facies can be classified as burial metamorphism because there is an overall increase in metamorphic grade with stratigraphic depth in the individual volcanic sequences separated by regional unconformities some sequences display metamorphic patterns transitional to ocean floor and to geothermal field types reflecting variations along and across the andes in tectonic setting and thermal gradients volcanism was closely followed by metamorphism during each cycle characterizing the geological history of the central andes the episodic nature of the metamorphism has led to breaks in metamorphic grade at regional unconformities and repetition of facies series where strata of higher grade may even overlie those of lower grade the existence of permeability controlled distribution patterns of secondary minerals within individual flows shows that gradients of chemical activity rate of reaction and pfluid were acting in addition to temperature and p tot overall gradients during the regional metamorphism the alteration is accompanied by chemical changes and disturbances of the k ar and rb sr isotope systems similarities between mesozoic facies series in the western and eastern flanks of the andes are consistent with a mechanism of ensialic spreading subsidence

occurrence of zeolites in sedimentary rocks an overview zeolites have been known since the mid 1750s but prior to the early 1950s most reported occurrences of zeolites were in fracture fillings and amygdules in igneous rocks particularly basaltic lava flows indeed most of the large attractive zeolite specimens in museum collections were obtained from lavas in recent years zeolites have been recognized as important rock forming constituents in low grade metamorphic rocks and in a variety of sedimentary rocks most zeolites in sedimentary rocks are finely crystalline that is they occur as microscopic or submicroscopic crystals and they are therefore of little appeal to mineral collectors however deposits of this type are voluminous and have great geologic significance and economic potential zeolites are among the most common authigenic silicate minerals that occur in sedimentary rocks and they form in sedimentary rocks of diverse lithology age and depositional environment about twenty species of zeolites have been reported from sedimentary rocks but only eight zeolites commonly make up the major part of zeolitic rocks these are analcime chabazite clinoptilolite erionite heulandite laumontite mordenite and phillipsite this chapter will consider chiefly the zeolites in sedimentary rocks with emphasis on volcaniclastic deposits which contain the largest concentrations of zeolites the occurrence of zeolites in lava flows is mentioned only briefly journal articles on the occurrence and origin of natural zeolites have multiplied at a rapid rate since the mineralogy and geology of natural zeolites was first published in 1977 as volume 4 of the mineralogical society of america s reviews in mineralogy the present review will highlight areas of more recent research on the occurrence and origin of zeolites and some of the coexisting minerals a wide variety of zeolites has been identified in sedimentary deposits with the most common being clinoptilolite analcime heulandite laumontite and phillipsite less abundant zeolites include chabazite erionite mordenite natrolite

characterisation and potential economic interest of authigenic zeolites in continental sediments from nw mexico in nw mexico zeolite deposits of potential economic interest occur in continental sediments related to mid tertiary basin and range tectonism in central sonora where the stratigraphic column is thicker e g in the moctezuma basin two superposed sequences of sediments are distinguished on the basis of their lithology and stratigraphy they are known as the baucarit formation the lower sequence miocene in age and 300 to 400 m thick is indurated and consists mainly of sandstones and conglomerates the upper one of variable thickness consists of clays zeolites occur in both sequences as alteration products of volcanic glass in beds of white intercalated rhyolitic tuff previously known outcrops of zeolitites from rio batepito erionite tetuachi and san pedro ures heulandite group divisaderos chabazite and several other newly discovered occurrences are described in this work in terms of mineral association physical properties porosity thermal behaviour and chemical characteristics major and trace elements for individual crystals and bulk rock heulandite group minerals are also present as cement 30 by volume of the sandstones from the lower sequence amygdales and veins from basaltic flows intercalated within the lowest sediments contain a large variety of zeolite species chabazite stilbite phillipsite mesolite erionite thomsonite heulandite and analcime zeolites in the pyroclastic beds intercalated in the upper sequence represent the highest economic potential because they are essentially monomineralic and constitute up to 80 in volume of the whole rock because of the inhomogeneous distribution of amygdales zeolites in the basaltic flows have a low economic interest

metamorphic grade and porosity and permeability controls on mafic phyllosilicate distributions in a regional zeolite to greenschist facies transition of the north shore volcanic group minnesota the 8 km thick keweenawan metabasaltic north shore volcanic group in minnesota shows a continuous zeolite to greenschist facies progression through five zonal divisions mafic phyllosilicates are ubiquitous and a well developed smectite corrensite chlorite transition is observed this sequence provides an excellent framework in which the influence of regional thermal as opposed to local scale lithology porosity and permeability factors on this transition factors that are actively debated can be comprehensively documented on a regional scale at lowest grades zones 1 and 2 thomsonite scolecite and heulandite stilbite assemblages respectively tri smectitic phyllosilicates dominate and with increase in grade to zone 3 laumontite albite there is a marked step and compositional gap to corrensite with further increase in grade to zones 4 laumontite albite prehnite pumpellyite and 5 epidote albite actinolite chlorite becomes dominant although a spread in the x ray diffraction and microprobe data suggests that the corrensite to chlorite transition is continuous rather than stepwise analytically distinct corrensite and chlorite in one flow suggest a clear compositional gap between these two phases overall the data offer some support for a discontinuous smectite corrensite chlorite transition above the lowest grade zones 1 and 2 approximately 150 c the phyllosilicates vary on a local within flow scale related to morphological contrasts in flow lithology smectite is dominant in the massive flow units low porosity and permeability whereas corrensite or chlorite is dominant in the amygdaloidal flow tops high porosity and permeability these changes provide clear indication that once above a threshold of approximately 150 c fluid rock ratios have a strong control on the metamorphic process at low grade similarities in xmgo between smectite corrensite chlorite and xmgo of the whole rock show that even though smectite is a relict phase remaining in massive zones it continues to undergo crystal chemical change with increasing grade however contrasts between aliv in the same minerals are provisional indicators that other factors perhaps related to kinetic features linked to advective and diffusive modes of fluid transport may be involved

compositions and parageneses of secondary minerals in the onikobe geothermal system japan abstract parageneses and chemical compositions of secondary minerals in many core samples of the onikobe geothermal system japan were investigated in detail in order to evaluate the controls of geothermal waters on alterations of andesitic dacitic rocks depth zonations of secondary minerals were delineated for cazeolites as mordenite laumontite yugawaralite wairakite and clay minerals as smectite alkaline smectite chlorite smectite chlorite compositional variations with depth hence temperature are apparent for smectite chlorite and illite chlorite interstratified clay minerals but not for wairakite both prehnite and epidote at depth have fe rich compositions and become more aluminous with increasing depth the ubiquitous occurrence of pyrite and rare magnetite and the absence of hematite suggest that the onikobe system had fs2 fo2 conditions within the pyrite stability field the occurrence of abundant calcite and ca zeolites indicates that thermal waters at depth are neutral to slightly alkaline and xco2 is very low to stabilize ca al silicates this conclusion is consistent with the production of a remarkable amount of alkaline high temperature steam and thermal waters in a newly drilled production well

ionospheric signatures of a plasmaspheric plume over europe 1 previously ionospheric signatures of plasmaspheric plumes were reported only at the north american longitude sector this led to the hypothesis that the geomagnetic field configuration at those longitudes played a vital role in the observation of plasmaspheric plume signatures only over the american continent combining ground based gps total electron content tec eiscat incoherent scattering radar isr and dmsp f15 ion drift meter observations we have observed greatly elevated density over the european continent during storm recovery phase on 12 september 2005 the tec seen over europe has a tongue of enhanced ionization extending to higher latitudes which is identical to the plasmaspheric plume signatures that have been often observed over north america therefore our observations clearly demonstrate that ionospheric signatures of plasmaspheric plumes are not limited to the north american sector and suggest that they may be observed at any longitude as long as a dense array of instruments are available to identify these signatures citation yizengaw e m b moldwin and d a galvan 2006 ionospheric signatures of a plasmaspheric plume over europe geophys res lett 33 l17103 doi 10 1029 2006gl026597

episodic burial metamorphism in the andes a viable model burial metamorphism of regional extent throughout mesozoic to cenozoic sequences in the andean mountain belt has been attributed previously to a unique model of metamorphic development involving episodic 40 m y cycles of extensional basin formation burial metamorphism and then exhumation a main premise of this model is that breaks in metamorphic grade occur at major stratigraphic unconformities so marking successive metamorphic cycles this model is tested in a mesozoic cenozoic sequence east of santiago where three metamorphic episodes have been reported on the basis of sharp breaks in metamorphic grade at two main unconformities in metabasites from this area reaction progress in mafic phyllosilicates shows a continuum across the sequence without breaks at the unconformities there are differences in mineral assemblages between the various stratigraphic units from which contrasting subgreenschist facies can be recognized however consideration of the controls on mineral paragenesis at subgreenschist facies conditions demonstrates that these different facies cannot be used as evidence of sharp breaks in metamorphic grade at unconformities as has been reported in many previous publications thus metamorphic breaks within this andean section cannot be confirmed accordingly models of andean burial metamorphism linked to episodic tectonic cycles throughout the mesozoic and cenozoic appear unfounded

petrology of philippine geothermal systems and the application of alteration mineralogy to their assessment abstract philippine geothermal systems occur in the vicinity of large holocene calc alkaline volcanic complexes wells drilled in these areas encountered multiple intrusions the latest dikes are the subsurface manifestations of the youngest heat source commonly at least two hydrothermal regimes are juxtaposed in a single area with the latest being in equilibrium with the present temperature and chemical regime alteration by neutral ph water is pervasive and abundant a contact metamorphic aureole also occurs near intrusives alteration due to acid sulfate fluids is generally confined to permeable structures neutral ph alteration is divided into four zones on the basis of key clay minerals and two subzones are defined by calc silicates these are the smectite ambient to 180 c transition 180 230 c illite 230 320 c and biotite 270 340 c zones subzones are defined by epidote 250 340 c and amphibole 280 340 c the four main zones of acid alteration are kaolinite ambient to 120 c dickite kaolinite 120 200 c dickite pyrophyllite 200 250 c and pyrophyllite illite 230 320 c where relict high temperature alteration reaches the surface the area being drilled is usually the outflow zone of the present system these hydrothermal mineral assemblages are used 1 as geothermometers 2 to assist in determining the depth at which the production casing will be set during drilling 3 to estimate fluid ph and other chemical parameters 4 to predict possible corrosion and scaling tendencies of the fluids 5 as a measure of permeability and possible cold water influx into wells 6 as a guide to field hydrology and 7 to estimate roughly the thickness of the eroded overburden

a study on the nighttime midlatitude ionospheric trough constellation observing system for meteorology ionosphere and climate cosmic electron density profiles are used to investigate the nighttime midlatitudeionospheric trough mit we find that at midnight the longitudinally deepest mit occursto the west of the geomagnetic pole in both the northern and southern hemispheres duringthe equinox seasons and local summer the deepest mit could be ascribable to theenhanced depletion caused by horizontal neutral wind in the early evening the eastwardneutral wind prevails in the midlatitude f region which blows the plasma downwardwhere the declination is eastward in the northern hemisphere but westward in thesouthern hemisphere both lying to the west of the geomagnetic pole the downward driftwould enhance the plasma depletion for more molecular composition at lower altitude in addition we find for the first time that the location of nighttime mit minimumoscillated with a periodicity of 9 days and an amplitude of about 1 1 5 geomagneticlatitude during 2007 2008 associated with the recurrent high speed solar wind ourresults shed new light on the empirical description and numerical simulation of mit

possible ionosphere and atmosphere precursory analysis related to mw 6 0 earthquakes in japan abstract the attention towards possible link of earthquakes eqs and ionosphere in the form of seismo ionosphere anomalies sias has increased exponentially by utilizing new data and more accurate observations the integrated atmosphere and ionosphere monitoring satellites has played a decisive role in this development and provided detection and analysis of anomalies attributed to seismic processes in this paper we study eq anomalies in ionosphere from igs permanent global navigation satellite systems gnss based total electron content tec and fof2 parameter highest frequency reflected from the main ionospheric f2 layer on a vertical propagation path retrieved from stations operating within the seismogenic zone in japan for eqs of magnitude mw 6 0 furthermore spatial composite maps of geopotential height air temperature and outgoing long wave radiation olr from national oceanic and atmospheric administration national center for environmental prediction noaa ncep are analyzed to support the hypothesis of diffusion of sias through the atmosphere over the epicenter during the seismic preparation zone we find evidences of tec and fof2 anomalies in the analysis of nearby igs permanent stations within seismogenic zone on main shock day when geomagnetic activities remain quiet in addition atmospheric composite indices manifest anomalies attributed to the eq on the same day as tec and fof2 perturbations similarly differential ionosphere and atmosphere values indicate that eq abnormalities are significant on main shock day during ut 10 12 our results show that atmospheric and ionospheric measurements may play a role for the analysis and prediction of eqs

storm time plasma transport at middle and high latitudes associated with the large scale enhancement of the ionospheric convection electric field during disturbed geomagnetic conditions solar produced f region plasma is transported to and through the noontime cleft from a source region at middle and low latitudes in the afternoon sector as a result of the offset between the geomagnetic and geographic poles the afternoon sector region of strong sunward convection is shifted to increasingly lower geographic latitude throughout the interval between 12 ut and 24 ut a snowplow effect occurs in which the convection cell continually encounters fresh corotating ionospheric plasma along its equatorward edge producing a latitudinally narrow region of storm enhanced plasma density sed and increased total electron content which is advected toward higher latitudes in the noon sector the millstone hill incoherent scatter radar regularly observes sed as a spatially continuous large scale feature spanning local times between noon and midnight and at latitudes between the polar cap and its mid or low latitude source region for local times away from noon the latitude of most probable sed occurrence moves equatorward by 6 for an increase of 2 in the kp index during strong disturbances the topside sed is observed to be convecting sunward at 750 m s 1 with a flux of 1014 m 2 s 1 this feature accounts for the pronounced enhancement of ionospheric density near dusk at middle latitudes observed during the early stages of magnetic storms called the dusk effect and constitutes a source for the enhanced f region plasma observed in the polar cap during disturbed conditions

industrial mineral occurrences associated with cenozoic volcanic rocks of sardinia italy geological mineralogical geochemical features and genetic implications the most important industrial mineral im deposits associated with the cenozoic volcanics of sardinia include kaolin bentonite and zeolites though of less significance perlite and potassium feldspar are also important in local and national markets bentonite and to a lesser extent kaolin and perlite form economically viable deposits and zeolites appear as very important industrial mineral commodities for future economic development the market situation for potassium feldspar is still under evaluation for use in ceramics all these deposit types occur as alteration products of cenozoic volcanic rocks which were emplaced during three main volcanic cycles in the eocene ec 55 to 51 ma oligocene miocene omc 32 to 13 ma and pliocene pleistocene ppc 5 to 0 1 ma kaolin bentonite zeolites and potassium feldspar occur as alteration products of the omc volcanites perlite occurs as an alteration product of the ppc volcanites all deposits have generally derived from the alteration of the most acidic members of the cenozoic volcanic rocks rhyolites to rhyodacites but differences among the associated ore forming phenomena are recognized hydrothermal sensu stricto deuteric alteration and weathering are the most important processes involved in ore formation weathering although of minor importance can also contribute to enhance the alteration of the deposits formed by hydrothermal and deuteric processes the extent and type of occurrences are mainly controlled by the local geological and structural features and the environmental geochemical conditions kaolin occurs in three main districts at romana and tresnuraghes it is hosted within ignimbritic sequences while at serrenti furtei it is found in pyroclastic flows and ash flow tuffs kaolin formed by hydrothermal processes occurs in high sulfidation romana and serrenti furtei and low sulfidation tresnuraghes type epithermal systems the alteration is proximal to the feeder conduits and structural setting controls kaolin formation bentonite is widespread throughout sardinia deposits occur as stratiform mineral bodies in situ altered within poor welded pumice rich and ash rich layers and also as distal fall out deposits as lenticular bodies interlayered within the miocene sedimentary sequences the former originated by deuteric alteration and formation is mainly controlled by lithology whereas the second type originated by weathering which altered the volcanic ash lenses deposited in lacustrine and or fluvial deltaic environments

east west coast differences in total electron content over the continental us 1 total electron content tec measurements made by a network of dense gps receivers over the continental us are used to investigate ionospheric longitudinal differences we find that the evening tec is substantially higher on the us east coast than on the west and vice versa for the morning tec the longitudinal difference displays a clear diurnal variation through an analysis of morning evening variability in the east west tec difference minimum variability is found to coincide with the longitudes of zero magnetic declination over the continental us we suggest that these new findings of longitudinal differences in ionospheric tec at midlatitudes are caused by the longitudinal difference in magnetic declination combined with the effects of thermospheric zonal winds which are subject to directional reversal over the course of a day this study indicates that longitudinal variations in tec measurements contain critical information on thermospheric zonal winds the proposed declination zonal wind mechanism may also provide a new insight into longitude ut changes at midlatitudes on a global scale as well as into some geospace disturbances

ionospheric redistribution during geomagnetic storms 1 the abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms recent reports suggest that the magnitude of the plasma density enhancement depends on the ut of storm onset this possibility is investigated over a 7year period using global maps of ionospheric total electron content tec produced at the jet propulsion laboratory the analysis confirms that the american sector exhibits on average larger storm time enhancement in ionospheric plasma content up to 50 in the afternoon middle latitude region and 30 in the vicinity of the high latitude auroral cusp with largest effect in the southern hemisphere we investigate whether this effect is related to the magnitude of the causative magnetic storms using the same advanced dst index employed to sort the tec maps into quiet and active dst 100 nt sets we find variation in storm strength that corresponds closely to the tec variation but follows it by 3 6h for this and other reasons detailed in this report we conclude that the ut dependent peak in storm time tec is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the south american region the large dst variation suggests a possible system level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current possibly connected through ut dependent modulation of ion outflow

a new petrogenetic grid for low grade metabasites abstract we have used internally consistent thermodynamic data to present calculated phase equilibria for the system na2o cao mgo al2o3 sio2 h2o ncmash in the range 0 500 c and 0 1 10 kbar involving the phases anorthite glaucophane grossular heulandite jadeite laumontite lawsonite paragonite prehnite pumpellyite stilbite tremolite wairakite zoisite with excess albite clinochlore quartz and pure water average activity terms derived from published mineral chemical data were included for clinochlore glaucophane prehnite pumpellyite tremolite and zoisite the new petrogenetic grid delineates stability fields and parageneses of common index minerals in zeolite prehniteactinolite prehnite pumpellyite pumpellyite actinolite blueschist and greenschist facies metabasites the stability fields of mineral assemblages containing prehnite pumpellyite epidote actinolite albite chlorite quartz were analysed in some detail using activity data calculated from five specific samples for example the prehnite actinolite facies covers a p t field ranging from about 220 to 320 c at pressures below 4 5 kbar the transition from the prehnite actinolite and pumpellyite actinolite to greenschist facies occurs at about 250 300 c at 1 3 kbar and at about 250 350 c at 3 8 kbar p t fields of individual facies overlap considerably due to variations in chemical composition

a numerical study of the storm surge generated by tropical cyclone jane abstract in 1983 tropical cyclone jane crossed the north west coast of australia generating a storm surge currents associated with this storm surge were recorded at two offshore moorings south of the cyclone track the data from these moorings are suggestive of the propagation of a continental shelf wave between the two stations this hypothesis is tested by carrying out a numerical simulation of this storm surge based on the depth integrated shallow water equations with wind wave enhanced bottom friction analysis of the numerical results shows that the storm surge can be interpreted as due to continental shelf waves

effects of wind trend and gustiness on the sea drag lake george study 1 the air sea coupling is usually parameterized in terms of the drag coefficient cd but the scatter of experimental data around such dependences is very significant and has not improved noticeably over some 30 years in the paper which is meant to be the first in a series a complex approach to the problem is suggested multiple mechanisms contributing into the sea drag are to be singled out studied separately evaluated and then reunited in a joint parameterization for cd dependences of the drag coefficient on the wind speed and sea state and effects of wind trends and gustiness are investigated in detail gustiness is found to be responsible for the most distant outliers our approach also combines an experimental lake george study with theoretical investigations conducted by means of the wowc wind over waves coupling model overall agreement of the model with measured wind stresses is quite good within 20 for the bulk of the data lower envelopes of the drag dependences are an important result of the paper they provide some lake george ideal relationships for the sea drag almost any deviation from such conditions causes the drag to increase it is suggested that decrease of the drag with respect to the ideal conditions which exhibits itself in a number of known open ocean data sets would be caused by a momentum flux back from the waves to the wind due to long waves outrunning the wind behavior of the charnock parameter in terms of wave age is also considered

compositional variations in mafic phyllosilicates from regional low grade metabasites and application of the chlorite geothermometer mafic phyllosilicates in metabasites affected by low grade regional metamorphism from wales and eastern north greenland show variations in their structure and chemistry these variations are related to four mineral zones in these metabasites which are recognized on the presence absence of various key calc silicate minerals and also actinolite zones 1 and 2 equate with the zeolite facies zone 3 with the prehnite pumpellyite facies or prehnite actinolite facies in rocks with appropriate bulk rock composition and zone 4 with the greenschist facies whilst variations in fe fe mg in chlorite correlate closely with fe fe mg ratios in the whole rock other chemical variations are clearly unrelated to whole rock compositions contents of aliv are seen to increase systematically in samples from zone 1 through to zone 4 which relate to an increase in temperature calibration of alteration temperatures calculated using the chlorite geothermometer based on aliv contents developed for meta andesites in the los azufres geothermal system mexico against x values an estimate of the proportion of chlorite to swelling component in the mafic phyllosilicates shows a decrease in the swelling component in passing from zone 1 to zone 4 i e with an increase in temperature calculated temperatures compare favourably with published stability estimates for the various key calc silicates and actinolite these data indicate that the chlorite geothermometer although developed for meta andesites from a hydrothermal system does show a correlation with temperatures estimated from calc silicate assemblages in metabasites affected by low grade metamorphism developed on a regional scale

supplementary cementitious materials the current widespread use of calcium silicate or aluminate hydrate binder systems in the construction industry finds its roots in the antique world where mixtures of calcined lime and finely ground reactive alumino silicate materials were pioneered and developed as competent inorganic binders architectural remains of the minoan civilization 2000 1500 bc on crete have shown evidence of the combined use of slaked lime and additions of finely ground potsherds to produce stronger and more durable lime mortars suitable for water proof renderings in baths cisterns and aqueducts spence and cook 1983 it is not clear when and where mortar technology evolved to incorporate volcanic pumice and ashes as a functional supplement a plausible site would be the akrotiri settlement at santorin greece where archeological indications of strong ties with the minoan culture were found and large quantities of suitable highly siliceous volcanic ash were present this so called santorin earth has been used as a pozzolan in the eastern mediterranean until recently kitsopoulos and dunham 1996 evidence of the deliberate use of this and other volcanic materials by the ancient greeks dates back to at least 500 400 bc as uncovered at the ancient city of kamiros rhodes efstathiadis 1978 idorn 1997 in the subsequent centuries the technological knowledge was spread to the mainland papayianni and stefanidou 2007 and was eventually adopted and improved by the romans mehta 1987 the roman alternatives for santorin earth were volcanic pumices or tuff found in neighboring territories the most famous ones found in pozzuoli naples hence the name pozzolan and in segni latium preference was given to natural pozzolan sources but crushed ceramic waste was frequently used when natural deposits were not locally available the exceptional lifetime and preservation condition of some of the most famous roman buildings such as the pantheon or the pont du

ionospheric symmetry caused by geomagnetic declination over north america 1 we describe variations in total electron content tec in the north american sector exhibiting pronounced longitudinal progression and symmetry with respect to zero magnetic declination patterns were uncovered by applying an empirical orthogonal function eof decomposition procedure to a 12 year ground based american longitude sector gps tec data set the first eof mode describes overall average tec while the strong influence of geomagnetic declination on the midlatitude ionosphere is found in the second eof mode or the second most significant component we find a high degree of correlation between spatial variations in the second eof mode and vertical drifts driven by thermospheric zonal winds along with well organized temporal variation results strongly suggest a causative mechanism involving varying declination with longitude along with varying zonal wind climatology with local time season and solar cycle this study highlights the efficiency and key role played by the geomagnetic field effect in influencing mesoscale ionospheric structures over a broad midlatitude range

variation of the drag coefficient and its dependence on sea state using a gill propeller vane anemometer and resistance wave wires over a water column depth of 15 m simultaneous measurements of the momentum flux and sea surface wave spectra were acquired from the pisa mast 28 km offshore in the german bight during autumn and winter 1979 these data were analyzed to identify the relationship between wind stress and surface waves it was found that wind stresses for wind speeds above 15 m s were regularly higher than open ocean wind stresses as reported by smith 1980 and by large and pond 1981 for the same mean wind speed these results when described in terms of the drag coefficient compared closely with the results of sheppard et al 1972 who collected surface layer statistics over lough neagh northern ireland after modeling the surface waves of the north sea as a function of wave saturation or wave age it became evident that variations in the magnitude of the drag coefficient could be explained by coincident variations in the surface wave energy spectrum by applying the wave dependent roughness length model described by kitaigorodskii 1973 the north sea drag coefficient was predicted to be larger than drag coefficients reported from the open sea

international geomagnetic reference field the eleventh generation the eleventh generation of the international geomagnetic reference field igrf was adopted in december 2009 by the international association of geomagnetism and aeronomy working group v mod it updates the previous igrf generation with a definitive main field model for epoch 2005 0 a main field model for epoch 2010 0 and a linear predictive secular variation model for 2010 0 2015 0 in this note the equations defining the igrf model are provided along with the spherical harmonic coefficients for the eleventh generation maps of the magnetic declination inclination and total intensity for epoch 2010 0 and their predicted rates of change for 2010 0 2015 0 are presented the recent evolution of the south atlantic anomaly and magnetic pole positions are also examined