kornerupine sensu stricto associated with mafic and ultramafic rocks in the lutzow holm complex at akarui point east antarctica what is the source of boron

comprehensive chemical analyses of natural cordierites implications for exchange mechanisms abstract cordierite samples from pegmatites and metamorphic rocks have been analysed for major electron microprobe analysis empa and trace elements inductively coupled plasma mass spectrometry icp ms secondary ion mass spectrometry analyses sims as well as for h 2 o and co 2 coulometric titration and the results evaluated in conjunction with published data in order to determine which exchange mechanisms are significant apart from the homovalent substitutions femg 1 and mnmg 1 on the octahedral site some minor kna 1 on the ch0 channel site and fe 3 al 1 on the t 1 1 tetrahedral site the three most important substitution mechanisms are those for the incorporation of li on the octahedral sites nali 1 mg 1 and of be and other divalent cations on the tetrahedral t 1 1 site nabe 1 al 1 and na mg fe 2 1 al 1 the dominant role of the last vector is clearly demonstrated we propose a new generalized formula for cordierite ch na k 0 1 vi mg fe 2 mn li 2 iv si 5 iv al 3 iv al be mg fe 2 fe 3 o 18 x ch h 2 o co 2 our results show that the population of mg fe 2 on the t 1 1 site is limited to about 0 08 a p f u other exchange mechanisms that were encountered in experiments operate only under p t conditions or in bulk compositions that are rarely realized in nature routine analyses by electron microprobe in which li and be are not determined can be plotted as mg fe mn versus si al to assess whether significant amounts of li and be could be present these amounts can be calculated as li a p f u al na 4 and be a p f u 10 2al m 2 na

a statistical investigation of preearthquake ionospheric anomaly 1 empirical evidence of the preearthquake ionospheric anomalies peias is reported by statistically investigating the relationship between variations of the plasma frequency at the ionospheric f2 peak fof2 and 184 earthquakes with magnitude m 5 0 during 1994 1999 in the taiwan area the peia defined as the abnormal decrease more than about 25 in the ionospheric fof2 during the afternoon period 1200 1800 lt significantly occurs within 5 days before the earthquakes moreover the odds of earthquakes with peia increase with the earthquake magnitude but decrease with the distance from the epicenter to the ionosonde station these results indicate that the peia is energy related

statistical analysis of an ionospheric parameter as a base for earthquake prediction 1 this paper is related to the use of ionospheric density variations to tentatively predict earthquakes the results of this statistical analysis are presented as a function of various parameters the ion density was recorded by the low altitude satellite demeter during more than 6 years and a search for anomalies was automatically conducted with the complete data set in a second time a software checked if each anomaly could correspond to an earthquake the search was conducted at less than 1500 km from the anomaly positions and until 15 days after the anomaly time the earthquakes have been classified depending on their magnitude depth and position below the sea or inland this attempt to predict earthquakes of course generates a lot of false alarms and wrong detections nevertheless it is shown that the number of good detections increases with the magnitude of the earthquakes in average the number of perturbations is higher the day of the earthquake and then smoothly decreases for the days before earthquakes below the sea are better detected there are seismic areas close to the south atlantic magnetic anomaly and at high latitudes where the number of natural perturbations is too important to expect a high number of good detections finally when there are several perturbations corresponding to a single earthquake it is possible to combine their positions to have a better estimation of the location of the future epicenter however uncertainties about the time and the magnitude are large

oxygen isotope and total beta radioactivity measurements on 10 m ice cores from the antarctic peninsula as part of the glaciology of the antarctic peninsula gap programme the snow cover at 25 stations was sampled to 10 m depth for oxygen isotope and total radioactivity analysis the mean annual oxygen isotope ratio correlates satisfactorily with 10 m temperature despite the complex topography of the area and suggests on average that climatic trends in the region are fairly systematic the relationship with temperature is similar to that derived from a simple model in which an air mass initially of maritime subtropical characteristics is progressively cooled as it moves towards the region the detailed isotope profiles show that for future deep drilling the most easily interpretable climatic information will be found in the more continental areas on the cast coast and on the plateau in the south of the region the degree of continentality of particular sites is reflected in the amplitude of the annual wave in the upper portion of the isotope ratio profile as well as in the accumulation rate

stable isotope air temperature relationships in ice cores from dolleman island and the palmer land plateau antarctic peninsula whilst stable isotope analysis of ice cores yields the best quantitative evidence for past climate there remains considerable uncertainty about the detailed relationship between the isotopic composition and air temperature analysis of two ice cores from the antarctic peninsula a 47 2 m core from the palmer land plateau 74 oi s 70 38 w and a 32 m core from dolleman island 70035 2 s 60055 5 w has shown that an oxygen isotope temperature relationship exists at a resolution of inter annual variations during the period 1938 86 all the major regional temperature anomalies known from climatic records at several stations are visible in the isotope profiles including the overall temperature increase between 1960 and 1980 an isotope temperature gradient of 0 5 o 6 c is indicated for the climatic interpretation of isotopic fluctu

from sumatra 2004 to tohoku oki 2011 the systematic gps detection of the ionospheric signature induced by tsunamigenic earthquakes the recent tsunamigenic earthquake in tohoku 11 march 2011 strongly affirms one more time after the sumatra event 26 december 2004 the necessity to open new paradigms in oceanic monitoring detection of ionospheric anomalies following the sumatra tsunami demonstrated that ionosphere is sensitive to the tsunami propagation observations supported by modeling proved that tsunamigenic ionospheric anomalies are deterministic and reproducible by numerical modeling via the ocean neutral atmosphere ionosphere coupling mechanism in essence tsunami induces internal gravity waves propagating within the neutral atmosphere and detectable in the ionosphere most of the ionospheric anomalies produced by tsunamis were observed in the far field where the tsunami signature in the ionosphere is clearly identifiable in this work we highlight the early signature in the ionosphere produced by tsunamigenic earthquakes and observed by gps measuring the total electron content close to the epicenter we focus on the first hour after the seismic rupture we demonstrate that acoustic gravity waves generated at the epicenter by the direct vertical displacement of the source rupture and the gravity wave coupled with the tsunami can be discriminated with theoretical support we illustrate the systematic nature of those perturbations showing several observations nominally the ionospheric perturbation following the tsunamigenic earthquakes in sumatra on 26 december 2004 and 12 september 2007 in chile on 14 november 2007 in samoa on 29 september 2009 and the recent catastrophic tohoku oki event on 11 march 2011 based on the analytical description we provide tracks for further modeling efforts and clues for the interpretation of complex and thus often misleading observations the routine detection of the early ionospheric anomalies following the rupture highlights the role of ionospheric sounding in the future ocean monitoring and tsunami detection

gravity increase before the 2015 mw 7 8 nepal earthquake the 25 april 2015 nepal earthquake mw 7 8 ruptured a segment of the himalayan front fault zone four absolute gravimetric stations in southern tibet surveyed from 2010 2011 to 2013 and corrected for secular variations recorded up to 22 40 1 11 gal yr of gravity increase during this period the gravity increase is distinct from the long wavelength secular trends of gravity decrease over the tibetan plateau and may be related to interseismic mass change around the locked plate interface under the himalayan tibetan plateau we modeled the source region as a disk of 580 km in diameter which is consistent with the notion that much of the southern tibetan crust is involved in storing strain energy that drives the himalayan earthquakes if validated in other regions high precision ground measurements of absolute gravity may provide a useful method for monitoring mass changes in the source regions of potential large earthquakes

pre earthquake chain processes detected from ground to satellite altitude in preparation of the 2016 2017 seismic sequence in central italy abstract this work is based on the retrospective analysis of several geophysical observations to search for possible lithosphere atmosphere ionosphere coupling effects in the preparatory phase of the central italy seismic sequence 2016 2017 the major seismic events occurred on 24 august 2016 mw 6 0 amatrice earthquake 30 october 2016 norcia mainshock mw 6 5 and on 18 january 2017 four m5 events close to campotosto montereale the work consists of a multi parametric approach over different observables from ground and space the geomagnetic field from satellites and observatories atmospheric chemical physical composition with the comparison with other already published results from chemistry of groundwater and seismicity in particular we investigated the vector magnetic data from ingv ground l aquila and duronia magnetic observatories and esa swarm three satellite constellation in addition we searched for anomalies in physical chemical composition of the atmosphere using merra 2 climatological dataset over central italy before the start of the seismic sequence two anomalous conditions anticipating the seismic sequence by about 275 and 85 days from geomagnetic observatories and by about 240 days from satellite have been found furthermore two highly perturbed periods in atmosphere chemical physical composition that precede by 200 and 150 days the start of seismic sequence have been discovered a comparison with also other published papers results to validate and integrate our findings is finally presented we find a chain of some quasi synchronous anomalies and propose a global point of view demonstrating that the earthquake preparation phase affects the equilibrium of the earth system producing anomalies from around a year in lithosphere atmosphere and ionosphere

seismotectonics of the april may 2015 nepal earthquakes an assessment based on the aftershock patterns surface effects and deformational characteristics occurrence of the april 25 2015 mw 7 8 earthquake near gorkha central nepal and another one that followed on may 12 mw 7 3 located similar to 140 km to its east provides an exceptional opportunity to understand some new facets of himalayan earthquakes here we attempt to assess the seismotectonics of these earthquakes based on the deformational field generated by these events along with the spatial and temporal characteristics of their aftershocks when integrated with some of the post earthquake field observations including the localization of damage and surface deformation it became obvious that although the mainshock slip was mostly limited to the main himalayan thrust mht the rupture did not propagate to the main frontal thrust mft field evidence supported by the available insar imagery of the deformation field suggests that a component of slip could have emerged through a previously identified out of sequence thrust active thrust in the region that parallels the main central thrust mct known in the literature as a co linear physiographic transitional zone called pt2 termination of the first rupture triggering of the second large earthquake and distribution of aftershocks are also spatially constrained by the eastern extremity of pt2 mechanism of the 2015 sequence demonstrates that the out of sequence thrusts may accommodate part of the slip an aspect that needs to be considered in the current understanding of the mechanism of earthquakes originating on the mht c 2015 elsevier ltd all rights reserved

spacecraft observations of electromagnetic perturbations connected with seismic activity 1 results of a statistical study of intensity of vlf electromagnetic waves observed in the vicinity of earthquakes are presented a unique set of data obtained by the micro satellite demeter altitude of about 700 km nearly sun synchronous orbit and a robust two step data processing has been used in the first step all the measured data are used to construct a map of electromagnetic emissions containing a statistical description of wave intensity at a given point of the satellite orbit under given conditions in the second step the intensity measured close to earthquakes is analyzed using the statistical distribution of background intensity obtained in the first step the changes of wave intensity caused by seismic activity are investigated and their statistical significance is evaluated altogether more than 2 5 years of satellite data have been analyzed and about 9000 earthquakes with magnitudes larger than or equal to 4 8 that occurred all over the world during the analyzed period have been included in the study it is shown that during the night there is a statistically significant decrease by 4 6 db of the measured wave intensity shortly 0 4 hours before an intense surface depth less than or equal to 40 km earthquake

pre earthquake signals underlying physical processes abstract prior to large earthquakes the earth sends out transient signals sometimes strong more often subtle and fleeting these signals may consist of local magnetic field variations electromagnetic emissions over a wide range of frequencies a variety of atmospheric and ionospheric phenomena great uncertainty exists as to the nature of the processes that could produce such signals both inside the earth s crust and at the surface the absence of a comprehensive physical mechanism has led to a patchwork of explanations which are not internally consistent the recognition that most crustal rocks contain dormant electronic charge carriers in the form of peroxy defects o 3 si oo sio 3 holds the key to a deeper understanding of these pre earthquake signals from a solid state physics perspective when rocks are stressed peroxy links break releasing electronic charge carriers h known as positive holes the positive holes are highly mobile and can flow out of the stressed subvolume the situation is similar to that in a battery the h outflow is possible when the battery circuit closes the h outflow constitutes an electric current which generates magnetic field variations and low frequency em emissions when the positive holes arrive at the earth s surface they lead to ionization of air at the ground air interface under certain conditions corona discharges occur which cause rf emission the upward expansion of ionized air may be the reason for perturbations in the ionosphere recombination of h charge carriers at the surface leads to a spectroscopically distinct non thermal ir emission

mineral chemistry of ti rich biotite from pegmatite and metapelitic granulites of the kerala khondalite belt southeast india petrology and further insight into titanium substitutions precise chemical composition including fe 3 and h of biotite from a pegmatite dike and its host granulite from the kerala khondalite belt of se india has been determined using a multi technique approach involving emp sims mossbauer and c h n elemental analysis biotite in these rocks formed at t 800 850 c and p 5 1 kbar the full analyses were normalized on the basis of o 12 x y z oh x cl y f z biotite in the pegmatite is ti f and cl rich 0 33 0 46 and 0 16 apfu respectively h 2 o poor oh 0 86 pfu has x mg 0 49 and fe 3 fe tot 3 the low octahedral vacancies 0 06 pfu and the high oxygen content in the hydroxyl site oh f cl 1 49 pfu confirm the role of the ti oxy substitution as a major exchange vector in these high t biotites in the host granulite fine grained biotite is fe 3 free has low cl 0 03 apfu and more variable composition with ti f and x mg in the ranges 0 26 0 36 0 52 0 67 and 0 67 0 77 respectively the number of octahedral vacancies is relatively large 0 10 0 18 pfu and the sum of volatiles oh f cl varies from 1 71 to 2 06 pfu systematic variations of x mg are a function of the microstructural position and are in agreement with retrograde exchange reactions biotite included in or in contact with garnet has the maximum values whereas crystals in the matrix have the minima titanium has systematic negative correlations with f x mg and oh f cl whereas al and octahedral vacancies are virtually constant these trends indicate that the ti vacancy along with substitutions involving al cannot explain the observed short scale variations conversely the ti oxy exchange appears to be active resulting from combination of two vectors the more conventional hydroxylation ti 4 2o 2 fe mg 2 2oh and the fluorination ti 4 2o 2 fe mg 2 2f the systematic retrograde redistribution involves not only fe and mg as commonly observed but also ti f and h in a way such to eliminate the primary ti oxy component of biotite

decadal timescale links between antarctic peninsula ice core oxygen 18 deuterium and temperature the antarctic peninsula region has exprienced a long term warming trend over the twentieth century with the 1971 90 mean at faraday being 1 9 c warmer than the mean over 1903 41 based on expedition reports for the period prior to 1900 there is conflicting evidence from different data sources an initial interpretation of isotopic data from ice cores suggests that the nineteenth century was warmer than the twentieth century in contrast snow accumulation rate data for the nineteenth century from the same ice cores suggest lower temperatures here we investigate these facts by studying the links between atmospheric temperature over the antarctic peninsula circulation parameters and isotopic data over the period of instrumental records we show that the relationships between these variables are complex and highly spatially variable in particular the correlations between temperature and 18o and d are generally of the order r 0 5 or less on timescales of one to five years conflicts between evidenc

additional attenuation of natural vlf electromagnetic waves observed by the demeter spacecraft resulting from preseismic activity 1 we use vlf electromagnetic wave data measured by the demeter detection of electro magnetic emissions transmitted from earthquake regions satellite at an altitude of about 700 km to check for the presence of statistically significant changes of natural wave intensity due to signals from lightning related to preseismic activity all the relevant data acquired by demeter during almost 6 5 years of the mission have been analyzed using a robust two step data processing schema this enables us to compare data from the vicinity of about 8400 earthquakes with an unperturbed background distribution based on data collected during the whole demeter mission and to evaluate the statistical significance of the observed effects we confirm previously reported results of a small but statistically significant decrease of the wave intensity by 2 db at frequencies of about 1 7 khz the effect is observed for a few hours before the times of the main shocks it occurs during the night the effect is stronger between march and august at higher latitudes and for the positions of hypocenters below the sea we suggest an explanation based on changed properties of the lower boundary of the ionosphere which leads to a decrease of the intensity of lightning generated whistlers observed at the spacecraft altitude this effect might result from a lowering of the ionosphere associated with an increase in the electrical conductivity of the lower troposphere due to an additional ionization of air molecules at the earth s surface prior to earthquakes

contact metamorphism in pelitic rocks on the island of kos greece eastern aegean sea a test for the na in cordierite thermometer into cordierite by a coupled substitution involving tetrahedral and most of the applicable thermometers involving cordierite require octahedral sites whereas na may not be charge balanced by additional fe mg phases and knowledge of pressure and fluid phase lattice oxygen the results obtained suggest that the experimentally composition these conditions are not necessarily met with natural established relationship between na contents of cordierite and cordierite bearing metamorphic rocks a potential pressure intemperature is a useful thermometer for cordieriteand plagioclasedependent geothermometer for cordieriteand plagioclase bearing bearing metapelitic rocks the nature of na incorporation in cordierite rocks is the experimentally determined inverse linear relationship and its relation to fluid composition however must be constrained between temperature and na contents of mg cordierite coexisting by further experiments with naoh or albite and naoh in this paper the na incordierite thermometer is empirically tested on cordierite bearing metapelites from the island of kos contact metamorphosed by a quartz monzonite intrusion the variety of phase assemblages in the metapelites allows for tight constraints to be placed on temperatures

a 1400 year oxygen isotope history from the ross sea area antarctica four ice cores from the ross sea drainage antarctica show patterns of 5180 variations on a time scale of decades to centuries over the last 1400 years without change in the long term average 5180 century scale 5180 fluctuations in the two cores drilled in the ross ice shelf at station j 9 82 23 s 168 38 w elevation 60 m are highly correlated p 30 000 a of the 1978 1 9 core thus represents local conditions over at least 102 m and on time scales of 100 years and longer regional correlations between the 1 9 5180 records and those from ridge bc 82 54 s 136 40 w elevation 509m and the dominion range 85 15 s 166 10 e elevation 2700 m are barely significant p 0 05 for j 9 76 and dominion range 580 to 1400 years ago or absent the failure to find clear regional isotope trends related to climate fluctuations may reflect the finding that between 1957 and 1982 the area was in the transition zone between areas with opposite temperature trends and showed little or no temperature change the fact that the records nevertheless show significant 5180 fluctuations highlights the need to base regional climate reconstructions on a regional suite of ice core records

a rare garnet tourmaline sillimanite biotite ilmenite quartz assemblage from the granulite facies region of south central massachusetts a rare lithology consisting of garnet tourmaline sillimanite biotite ilmenite quartz has been found within the granulite facies region of south central massachusetts the homogeneous ti rich oxy dravitic tourmaline x mg mg mg fe 0 72 0 77 falls into the alkali group and is similar in composition to lower grade tourmaline found in corresponding metapelitic rocks in maine charge balancing calculations and binary diagrams suggest that like biotite in the region tourmaline has undergone deprotonation by means of the exchange vectors alor 1 oh 1 and tio 2 r 1 oh 2 where r represents fe mg the restriction of a concordant tourmaline rich horizon in otherwise tourmaline free rocks of this granulite facies region suggests that either 1 b released during prograde fluid absent dehydration reactions of muscovite and biotite was locally available in a fluid phase or melt for later crystallization near the peak of granulite facies metamorphism along pathways that provided a conduit for fluid migration or 2 that this is simply a b rich compositional horizon tourmalinite that survived anatexis and granulite facies metamorphism and that records the incipient conditions of tourmaline breakdown and subsequent recrystallization near or post peak metamorphism

potential earthquake precursory pattern from space the 2015 nepal event as seen by magnetic swarm satellites abstract a large earthquake of 7 8 magnitude occurred on 25 april 2015 06 26 utc with the epicenter in nepal here taking advantage of measurements provided by the swarm magnetic satellites we investigate the possibility to detect some series of pre earthquake magnetic anomalous signals likely due to a lithosphere atmosphere ionosphere coupling that can be a potential earthquake precursory pattern different techniques have been applied to swarm data available during two months around earthquake occurrence from the detected magnetic anomalies series during night and magnetically quiet times or with an automatic detection algorithm we show that the cumulative number of anomalies follows the same typical power law behavior of a critical system approaching its critical time and hence recovers as the typical recovery phase after a large event the similarity of this behavior with the one obtained from seismic data analysis and the application of the analyses also to another period without significant seismicity do support a lithospheric linked origin of the observed magnetic anomalies we suggest that they might be connected to the preparation phase of the nepal earthquake

mobile element analysis by secondary ion mass spectrometry sims of impactite matrix samples from the yaxcopoil 1 drill core in the chicxulub impact structure the concentrations of the fluid mobile trace elements lithium beryllium boron and barium were measured in samples of the altered matrix of several impactite breccias of the yaxcopoil 1 drill core using secondary ion mass spectrometry sims to determine the extent of transport due to aqueous or hydrothermal processes three of the elements li be and b have higher concentrations in the upper suevite impact breccias than in the lower impact melt deposits by factors of 3 5 2 2 and 1 5 respectively lithium and b are the most enriched elements up section and appear to have had the greatest mobility the similar fractionation of li and b is consistent with fluid transport and alteration under low temperature conditions of less than 150 c based on published experimental studies in contrast to li be and b the concentration of ba in the altered matrix materials decreases upward in the section and the concentration of ba in the matrix is an order of magnitude less than the bulk concentrations likely due to the presence of barite the origin of the elemental variations with depth may be related to different protolith compositions in the upper versus the lower impactite units a different protolith in the altered matrix is suggested by the mg rich composition of the lower units versus the al rich composition of the upper units which largely correlates with the mobile element variations the possibility that vertical transport of mobile elements is due to a postimpact hydrothermal system is supported by published data showing that the sediments immediately overlying the impactites are enriched in mobile elements derived from a hydrothermal system however the mobile elements in the sediments do not have to originate from the underlying impactites in conclusion our data suggests that the impactites at this location did not experience extensive high temperature hydrothermal processing and that only limited transport of some elements including li be and b occurred

f rich phlogopite stability in ultra high temperature metapelites from the napier complex east antarctica fluorine rich phlogopite f content up to 8 wt f f oh 0 9 in ultra high temperature metapelitic granulites from the napier complex east antarctica is associated with aluminous orthopyroxene osumilite sapphirine garnet and quartz textural relationships imply that some of the phlogopite is of primary origin and stable under ultra high temperature conditions this is in accord with recent experimental evidence on the stability of f rich phlogopite because the f rich phlogopite also occurs as rounded inclusions in aluminous orthopyroxene al 2 o 3 up to 12 8 wt sapphirine osumilite and garnet it is inferred that the ultra high temperature mineral assemblages which includes these minerals formed during prograde partial melting reactions at the expense of phlogopite at a depth of less than 30 km thus the coarse grained peak metamorphic assemblages formed below 9 kbar and there is no evidence the rocks underwent any significant degree of decompression during or soon after peak metamorphic conditions the phlogopite breakdown reactions we suggest on the basis of textural arguments differ from those postulated from experiments on f free systems

extending the antarctic meteorological record using ice sheet temperature profiles abstract two vertical ice temperature profiles from locations in the antarctic peninsula unaffected by meltwater are presented a simple time dependent heat diffusion advection model is used to infer broad surface temperature variations in the antarctic peninsula over the century prior to the start of local meteorological records air temperature records from two representative meteorological stations faraday and halley are used to determine the ice surface boundary conditions in the later stages of the model runs earlier temperature histories are then devised to provide best fits between the modeled and observed ice temperature profiles results of the modeling suggest that the surface temperature in the antarctic peninsula dropped by 1 6 0 2 c between the beginning of the nineteenth century and the start of the faraday record in 1944 on time scales of several decades the faraday air temperature record began during a period colder than the average and temperatures in the early 1800s were probably

an infrared spectroscopic ir and light element li be na study of cordierites from the bamble sector south norway abstract infrared absorption spectra and light element contents of several natural cordierites across the arendal amphibolite granulite facies transition bamble sector south norway are presented the infrared spectra record h2o both type i and type ii and co2 as fluid constituents in the channels co and hydrocarbons were not detected type ii water and ca na k are correlated and show a 2 1 molar ratio the infrared and light element data indicate a decrease of na type ii h2o co2 and li with metamorphic grade while type i h2o and be are variable the decrease of these volatiles and alkalies and the low total volatile contents of the granulite facies cordierites are best explained by progressive dehydration and decarbonation processes possibly related to partial melting a progressive change of the x h 2 o h 2 o h 2 o co 2 ratio in the cordierites across the transition as suggested by previous studies is not observed greenschist to low amphibolite facies re equilibrated cordierites show a significant increase in either co2 or h2o co2 na is introduced at some localities the retrograde fluid phase is calculated to be co2 rich

b and li in proterozoic metapelites from the black hills u s a implications for the origin of leucogranitic magmas the abundance and distribution of b and li in metasedimentary rocks and in the harney peak granite hpg in the black hills south dakota u s a elucidate the behavior of these two elements during 1 regional metamorphism that began at 1760 ma 2 subsequent contact metamorphism associated with emplacement of the hpg and associated pegmatites at 1715 ma and 3 anatexis leading to production of the granite there is no clear evidence for changes in b and li concentrations with progressive regional metamorphism of the metapelites from chlorite biotite grade up to staurolite grade rocks outside the pegmatite aureole that surround the hpg have average b contents of 80 ppm there is no correlation of b with other elements in the pelitic schists which indicates that none of the major phases is the dominant host for b boron content is mainly controlled by small amounts of randomly distributed tourmaline that was identified in alpha track maps of thin sections in the aureole of the granite b concentrations are depleted in many samples the depletion is attributed to consumption of tourmaline during interaction of the rocks with alkalic fluids the average li contents in metapelites far away from the hpg are also 80 ppm near the hpg li concentrations reach roughly 190 ppm indicating significant metasomatism by fluids that emanated from the granite and pegmatites the concentrations of b and li in the low grade metapelites are sufficient to explain their abundances in the hpg if the granite formed by partial melting of the metapelites and if there was total breakdown of tourmaline stabilization of tourmaline in leucogranites is not necessarily related to sources enriched in b but may be related to its competition for fe and mg with biotite

synthesis of beryllian sapphirine in the system mgo beo al2o3 sio2 h2o and comparison with naturally occurring beryllian sapphirine and khmaralite part 1 experiments tem and xrd beryllian sapphirine mg 4 x al 4 x a1 4 x 2 y be y si 2 x y o 1 8 o 2 has been synthesized from starting compositions with y 1 at x 0 and y 0 5 at x 0 5 p 0 1 1 3 gpa t 700 1350 c electron diffraction shows the sapphirines are dominantly the 1a polytype but lamellae of a 2m phase are consistently present this is the first 2m sapphirine synthesized in the laboratory and the first known to be devoid of fe 2 no superstructure reflections corresponding to the doubled tetrahedral chain repeat of khmaralite were observed probably due to insufficient annealing time cell parameters of the synthetic sapphirine decreased strongly and linearly with be content 2 7 vol decrease from y 0 to y 1 in agreement with crystal chemical considerations experiments with starting compositions of y 1 0 resulted in additional crystalline phases either coexisting with the limiting sapphirine y 1 or without it at 900 c 1 3 2 0 gpa the saturating assemblage is surinamite chrysoberyl forsterite which is chemically equivalent to sapphirine with y 1 5 the current lack of natural khmaralite with be 0 78 cations per formula unit pfu is likely due to the bulk composition of the host rocks being too rich in sio 2 and al 2 o 3 for forsterite to be stable addition of beo to the mgo al 2 o 3 sio 2 system evidently enlarges the stability field of sapphirine forsterite relative to its restricted range in the beo free system

a 400 years isotope record of the antarctic peninsula climate a 400 year deuterium record has been obtained from a 154 3 m ice core drilled on dalinger dome james ross island antarctic peninsula based on a comparison between the isotope profile and the temperature data over the recent period aristarain et al 1986 an interpretation is proposed in terms of temperature changes the warmest part of this proxy record occurs around 1850 with as a salient feature a temperature decline of 2 c from that time up until present conditions this feature at odds with the long timescale warming trend recorded for both hemispheres over the same period likely reflects a regional characteristic related to the lack of a high latitude low latitude link in southern hemisphere circulation patterns

results of ultra low frequency magnetic field measurements during the guam earthquake of 8 august 1993 we report the results of measurements of ultra low frequency magnetic noise during a large earthquake ms 7 1 at guam of 8 august 1993 depth 60 km the ulf observing system is located in the guam island about 65 km from the epicenter several distinct features of this analysis are summarized 1 we have proposed rather sophisticated statistical analyses monthly mean standard deviation in order to estimate the wave intensity and polarization i e ratio z h 2 a comparison between the ulf wave activity and kp is useful in distinguishing between the space geomagnetic pulsations and non space emissions 3 then the use of the ratio z h is found to be of essential importance in discrimating the emissions presumably of seismic origin from space plasma waves 4 the statistical analysis of the temporal evolution of this ratio has yielded that it shows a broad maximum only about one month before the earthquake and this suggests that the emissions during this period are very likely to be magnetic precursors 5 the temporal variation of z component is similar to that for the loma prieta earthquake such that it shows a broad maximum ten days two weeks before the earthquake and another increase a few days before the earthquake 6 the emissions presumably associated with the earthquake are of noise like nature and their main frequency is 0 02 0 05 hz with maximum intensity 0 1 nt

low frequency magnetic field measurements near the epicenter of the ms 7 1 loma prieta earthquake the authors report the results of measurements of low frequency magnetic noise by two independent monitoring systems prior to the occurrence of the m sub s 7 1 loma prieta earthquake of 17 october 1989 their measurements cover 25 narrow frequency bands in the more than six decade frequency range 0 01 hz 32 khz with a time resolution varying from a half hour in the ulf range 0 01 10 hz to one second in the elf vlf range 10 hz 32 khz the ulf system is located near corralitos about 7 km from the epicenter the elf vlf system is located on the stanford campus about 52 km from the epicenter analysis of the elf vlf system is located on the stanford campus about 52 km from the epicenter analysis of the elf vlf data has revealed no precursor activity that they can identify at this time however the ulf data have some distinctive and anomalous features first a narrow band signal appeared in the range 0 05 0 2 hz around september 12 and persisted until the appearance of the second anomalous feature which consisted of a substantial increase in the noise background starting on 5 october and covering almost the entire frequency range of the ulf system third there was an anomalousmore dip in the noise background in the range 0 2 5 hz starting one day ahead of the earthquake finally and perhaps most compelling there was an increase to an exceptionally high level of activity in the range 0 01 0 5 hz starting approximately three hours before the earthquake there do not appear to have been any magnetic field fluctuations originating in the upper atmosphere that can account for this increase further while the systems are sensitive to motion seismic measurements indicate that there were no significant shocks preceding the quake thus the various anomalous features in the data and in particular the large amplitude increase in activity starting three hours before the quake may have been magnetic precursors less

coseismic deformations of the 2015 mw 7 8 gorkha earthquake and interseismic strain accumulation in the himalayan tectonic belt and tibetan plateau abstract the principal strain rate derived from gps velocities from the tibetan plateau and the india plate shows that the himalayan tectonic belt exhibits compression deformation in a ne ns ne direction from the west to the east the gps velocity profiles reflect that the distribution of strain accumulation is uneven there is a 17 1 mm yr compressive deformation distributed over 400 km along 85 e longitude a 20 9 22 2 mm yr compressive deformation dispersed across 400 500 km along 79 e longitude and a 15 3 16 9 mm yr compressive deformation spread across 500 600 km along 91 e longitude the mw 7 8 gorkha earthquake occurred at the edge of an intense compression deformation zone of about 6 0 10 8 yr in a north south direction and an about 90 compressive strain is absorbed in the 300 km region near the main frontal thrust mft coseismic displacements larger than three standard deviations 3sd are mainly concentrated within 360 km from the epicenter the nodal plane of the main shock divides the areas where tensile strain release in an exponential attenuation pattern is dominant to the north and where compressive strain with upward movement is dominant to the south the results inversed by the sdm program reveal that the maximal slip of the gorkha earthquake is 5 33 m and its moment magnitude is mw 7 85 and the largest stress drop is 4 21 mpa slips larger than 0 5 m are mainly distributed in a region approximately 135 km 105 km which show that the rupture of the gorkha earthquake does not reach the surface finally we estimate that the recurrence period of this earthquake is about 166 20 years according to the strain accumulation before the earthquake and the coseismic release feature

can electromagnetic disturbances related to the recent great earthquakes be detected by satellite magnetometers abstract on december 26 2004 the world s fourth largest earthquake since 1900 and the largest since the 1964 prince william sound alaska earthquake occurred off the west coast of northern sumatra with a magnitude of 9 3 on march 28 2005 another event of magnitude 8 7 took place in the same region the december 26 2004 earthquake has prompted scientists to investigate possible electromagnetic signatures of this event using ground magnetic observations iyemori et al iyemori t et al 2005 geomagnetic pulsations caused by the sumatra earthquake on december 26 2004 geophys res lett 32 l20807 doi 10 1029 2005gl024083 have suggested that a 3 6 min long geomagnetic pulsation observed shortly after this event was generated by the earthquake they have speculated that a 30 s magnetic pulsation was also caused by the earthquake here for the first time champ satellite magnetic and electron density data are examined to find out if electromagnetic signatures which are possibly related to these recent megathrust earthquakes are observed in satellite magnetic data we have shown that some specific features are observed after the two earthquakes with periods of about 16 and 30 s our results favor an external source origin for the 30 s pulsation moreover after more than 1 h champ magnetic data indicate the existence of a feature characterized by the same parameters duration amplitude and frequency content which could be associated with each earthquake respectively further investigations are required in order to answer the question of whether these signals can be associated with earthquakes and to assign their possible usefulness with respect to earthquake development

lithosphere atmosphere ionosphere coupling laic model an unified concept for earthquake precursors validation abstract the paper presents a conception of complex multidisciplinary approach to the problem of clarification the nature of short term earthquake precursors observed in atmosphere atmospheric electricity and in ionosphere and magnetosphere our approach is based on the most fundamental principles of tectonics giving understanding that earthquake is an ultimate result of relative movement of tectonic plates and blocks of different sizes different kind of gases methane helium hydrogen and carbon dioxide leaking from the crust can serve as carrier gases for radon including underwater seismically active faults radon action on atmospheric gases is similar to the cosmic rays effects in upper layers of atmosphere it is the air ionization and formation by ions the nucleus of water condensation condensation of water vapor is accompanied by the latent heat exhalation is the main cause for observing atmospheric thermal anomalies formation of large ion clusters changes the conductivity of boundary layer of atmosphere and parameters of the global electric circuit over the active tectonic faults variations of atmospheric electricity are the main source of ionospheric anomalies over seismically active areas lithosphere atmosphere ionosphere coupling laic model can explain most of these events as a synergy between different ground surface atmosphere and ionosphere processes and anomalous variations which are usually named as short term earthquake precursors a newly developed approach of interdisciplinary space terrestrial framework istf can provide also a verification of these precursory processes in seismically active regions the main outcome of this paper is the unified concept for systematic validation of different types of earthquake precursors united by physical basis in one common theory

fifth generation lithospheric magnetic field model from champ satellite measurements 1 six years of low orbit champ satellite magnetic measurements have provided an exceptionally high quality data resource for lithospheric magnetic field modeling and interpretation here we describe the fifth generation satellite only magnetic field model mf5 the model extends to spherical harmonic degree 100 as a result of careful data selection extensive corrections filtering and line leveling the model has low noise levels even if evaluated at the earth s surface the model is particularly suited for inferring large scale structure and composition of the lithosphere it is also meant to serve as the long wavelength part of continental and global scale marine and aeromagnetic anomaly maps

magnetic field and electron density anomalies from swarm satellites preceding the major earthquakes of the 2016 2017 amatrice norcia central italy seismic sequence a systematic inspection of the magnetic field and electron density recorded by swarm three satellite constellation over the seismic region hit by the 2016 2017 amatrice norcia central italy seismic sequence has allowed us to identify some possible precursory anomalies when disturbed periods of the geomagnetic conditions are properly taken into account and or avoided this paper aims at studying and interpreting the electromagnetic phenomena occurred before and during the 2016 2017 amatrice norcia central italy seismic sequence in order to look for any possible evidence of precursory anomalies results show magnetic field and electron density anomalies of four tracks that precede the major earthquakes of the seismic sequence after an inspection of the geomagnetic conditions a swarm charlie track acquired on 20 08 2016 that precedes by 3 2 days the beginning of the whole seismic sequence remains unexplainable with the normal geomagnetic disturbance phenomena of the earth s magnetic field furthermore we carry out a blind study of possible relationship between abnormal magnetic field signals detected by swarm satellites during geomagnetic quiet conditions and major seismic events from about 4 months before the start of the seismic sequence until about the first 8 months from the seismic sequence i e a total of one year of analysed data we find a very interesting increase of such anomalies starting about 40 days before the beginning of the seismic sequence it coincides and follows surface and atmospheric alterations resulting in a temporal sequence of anomalies from earth s surface up to ionosphere supporting the possibility of lithosphere atmosphere ionosphere coupling models

lower edge of locked main himalayan thrust unzipped by the 2015 gorkha earthquake faults are unlocked by earthquakes analysis of seismic data from the 2015 nepal earthquake shows that only part of the main himalayan thrust fault was unzipped by the quake leaving much of the fault locked and ready to slip in a future event

possible lithosphere atmosphere ionosphere coupling effects prior to the 2018 mw 7 5 indonesia earthquake from seismic atmospheric and ionospheric data abstract in this study we analyse lithosphere atmosphere ionosphere coupling laic effects to identify some phenomena that could possibly be linked to the preparation phase of the mw 7 5 earthquake occurred in indonesia on september 28th 2018 by investigating the eight months preceding the seismic event first we find a seismic acceleration that started two months before the mainshock then studying some physical properties of the atmosphere skin temperature total column water vapor and aerosol optical thickness we find two increases of atmospheric anomalies about 6 and 3 7 months before the mainshock and the latter one is very promising as a candidate for seismic related phenomena furthermore we investigate ionospheric disturbances by analysing the swarm and for the first time china seismo electromagnetic satellite cses magnetic and electron density data during quiet geomagnetic time from different techniques we find interesting anomalies concentrated around 2 7 months before the mainshock on august 19th 2018 swarm and cses showed an enhancement of the electron density during night time we critically discuss the possibility that such phenomenon can be a possible pre seismic induced ionospheric effect finally we performed a cumulative analysis using all detected anomalies as a test case for a possible chain of physical phenomena that could happen before the earthquake occurrence with this study we support the usefulness to collect and store large earth ground and satellite observational dataset that in the future could be useful to monitor in real time the seismic zones to anticipate earthquakes although nowadays there is no evidence about useful prediction capabilities

little ice age neoglacial paleoenvironmental conditions at siple station antarctica the 550 year records of 18 o and dust concentrations from siple station antarctica suggest warmer and less dusty atmospheric conditions from 1600 to 1830 a d which encompasses much of the northern hemisphere little ice age lia dust and 18 o data from south pole station indicate that the opposite conditions e g cooler and more dusty were prevalent there during the lia meteorological data from 1945 85 show that the lia temperature opposition between amundsen scott and siple inferred from 18 o is consistent with the present spatial distribution of surface temperature there is some observational evidence suggesting that under present conditions stronger zonal westerlies produce a temperature pattern similar to that of the lia these regional differences demonstrate that a suite of spatially distributed high resolution ice core records will be necessary to characterize the lia in antarctica

kornerupine parageneses in whiteschists and other magnesian rocks is kornerupine talc a high pressure assemblage equivalent to tourmaline orthoamphibole kornerupine fe mg mg fe al 9 si al b 5 o oh f 22 has been reported with talc in rocks from six localities worldwide but only at chilapila hill in the lufilian arc zambia do textural relationships imply that kornerupine krn equilibrated with talc tlc during a prograde metamorphic event at t 640 c p 13 kbar a prograde krn tlc assemblage has also been reported from mautia hill tanzania p 13 kbar in order to estimate possible constraints on the stability range for the kornerupine talc paragenesis in nature we constructed a p t diagram in the model system mgo al2o3 sio2 h2o mash for seven phases quartz qtz b free kornerupine sensu stricto anthophyllite ath chlorite chl cordierite crd kyanite ky and talc the minimum pressure for krn tlc ky stability in mash is close to that for ky tlc stability i e 6 8 kbar at t 780 c however in the natural system b2o3 and na2o are major constituents in krn and orthoamphibole oam respectively and dravitic tourmaline tur is widespread the critical assemblage alternative to krn tlc in nature is tur oam the upper pressure limit of tur ath is determined by the upper pressure for anthophyllite 7 7 10 5 kbar at 682 794 c in the mgo sio2 h2o system chernosky et al 1985 am mineral 70 223 236 and is undoubtedly higher in the presence of na2o cao and al2o3 at three of the six localities talc is a retrograde phase nonetheless it possibly equilibrated with kornerupine on the retrograde path or during a later metamorphic event at p t conditions appropriate for ky tlc at the sixth locality mulvoj southwestern pamir mountains tajikistan krn is found in the same thin section as talc and kyanite and all three minerals formed during a prograde metamorphic event at t 650 c p near 7 kbar however krn is restricted to a lens 4 to 6 mm thick of phlogopite anthophyllite tur and it does not touch either talc or kyanite a reaction relating the mulvoj and chilapila hill krn tlc ky qtz tur parageneses is calculated from compositions in the mulvoj rock to be 0 40tur 2 55ath 1 33h2o 0 27f krn 2 16tlc 0 36b2o3 0 02rutile 0 19na2o 0 17cao given the difference in metamorphic pressures estimated for mulvoj and chilapila hill krn tlc is inferred to be favored by increasing pressure as well as by low na2o and cao contents some feo f fe2o3 and beo are present in measurable amounts in at least one of the phases in the mulvoj and chilapila hill whiteschists e g krn contains 0 24 0 67 wt beo but the effect of these constituents is subordinate to that of na2o cao and b2o3 the krn tlc could be a more important assemblage in b bearing whiteschists than has been reported to date particularly at pressures where orthoamphibole is no longer stable

ionospheric anomalies possibly associated with m 6 0 earthquakes in the japan area during 1998 2010 case studies and statistical study abstract in this paper we examine pre earthquake ionospheric anomalies in time series and perform a statistical test by using total electron content tec derived from global ionosphere maps gim around the japan area for the first time the normalized gim tec gim tec which is computed based on 15 days backward running mean of gim tec have been investigated for minimizing possible confounding effects of consecutive earthquakes and identify the abnormal signals meanwhile to reduce the effect of strong geomagnetic activities such as geomagnetic storms the criterion for removing the gim tec data have been adapted that is when dst index exceeds 60 nt temporal variations of gim tec for large and destructive earthquakes in japan have been studied which are the 2004 mid niigata prefecture earthquake m6 8 its aftershock m6 1 the 2007 offshore mid niigata earthquake m6 8 and the 2008 iwate miyagi nairiku earthquake m7 2 although there are some positive and negative tec anomalies before and after the four earthquakes there is a tendency that positive tec anomalies appear 1 5 days before all the above earthquakes even during the quiet geomagnetic condition superposed epoch analyses have been performed for the statistical analysis of tec anomalies associated with m 6 0 earthquakes during the 12 year period of may 1998 may 2010 the statistical result indicates the significance of the positive tec anomalies 1 5 days before earthquakes within 1000 km from the epicenter around japan

boron geochemistry of the lower crust evidence from granulite terranes and deep crustal xenoliths abstract boron contents are uniformly low in more than 100 granulites from exposed terranes in india norway and scotland and from xenolith suites in the western usa averages for the terranes 2 5 ppm and for xenoliths 1 2 ppm suggest maximum b contents of about 2 1 ppm for the lower crust abundance distributions from exposed terranes are skewed to higher values as b has been added to some samples via retrograde fluids during decompression the samples studied include mafic to felsic lithologies of both igneous and sedimentary origin there is no correlation of b content with bulk composition or with protolith type in any of the suites studied boron is apparently depleted in all granulite protoliths during prograde metamorphism and dehydration similar depletions of b and other fluid mobile elements e g u cs with respect to rare earth elements ree zr ba rb and k 2 o are seemingly inconsistent with origin of granulites primarily via extraction of silicate melts these distinctive geochemical features are attributed to selective element transport in fluids released by devolatilization reactions anatexis is not necessarily precluded but dehydration of the subsolidus protolith normally would precede melting and lead to depletion of the fluid mobile elements compositions of any melts and restites eventually formed would reflect the effects of this antecedent process the systematic depletion of b and cs in granulites contrasts with the highly variable contents of most other incompatible elements determined for this reason the estimated lower crust abundance for b is relatively well constrained whereas abundance estimates for many other elements are model dependent have large uncertainties and are unlikely to be globally representative