tube like schlieren structures in the furstenstein intrusive complex bavarian forest germany evidence for melt segregation and magma flow at intraplutonic contacts abstract tube like schlieren structures occur at the boundary between two units of the furstenstein intrusive complex the tittling and the saldenburg granites we have analysed the magnetic fabrics petrographic variation and geochemistry of key examples of these structures in order to test the hypothesis that they originated as granitic microdiapirs the rims of the schlieren structures have high magnetic susceptibility compared to their interiors and surrounding granite due to the enrichment of biotite opaques the low anisotropy that characterizes the ams fabric is probably caused by magmatic flow hypersolidus microfabrics support this interpretation magnetic fabric orientation within the schlieren structures differs significantly from the ne sw trending magnetic foliation generally observed within the hosting tittling granite a steeply plunging magnetic lineation and a nne ssw girdle distribution of the magnetic foliation poles within the schlieren structures are consistent with the conical geometry of the schlieren structures evolved during the rise of the magma based on geochemistry granite in the schlieren structures is interpreted to be differentiated melt expelled from the tittling granite mush that formed after early crystallization of plagioclase we suggest that the schlieren structures are pockets of residual melt of the tittling granite that were mobilized buoyantly due to a thermal input from the neighbouring saldenburg granite the mafic rims of the schlieren structures formed as a result of early crystallization and subsequent accumulation due of the bagnold effect the results of the magnetic and geochemical investigations allow us to interpret the schlieren structures as diapiric in nature and consequently as within chamber diapirs sensu weinberg et al 2001

emplacement and deformation of granites during transpression magnetic fabrics of the archean sparrow pluton slave province canada abstract the sparrow pluton is part of the prosperous suite of two mica granites that crop out within amphibolite grade meta greywackes of the southern yellowknife domain in the slave province of the canadian shield the magnetic susceptibility k and the anisotropy of magnetic susceptibility ams were used to systematically map the structural patterns in the pluton and to establish the relationship between plutonism and late archean tectonics in the region paramagnetic fe phyllosilicates biotite chlorite and very fine grained magnetite contribute to k and to the ams the magnetic foliation and the magnetic lineation are predominantly controlled by the biotite fabrics and their orientations are consistent with the regional d 2 strain field the horizontal magnetic lineations in the sparrow pluton suggest a horizontal stretching component associated with the regional d 2 event the zonation defined by k values is compatible with a fold pattern trending parallel to the regional f 2 folds and s 2 foliation and to the magnetic fabric trends in the pluton the intensities and symmetries of the ams also define map patterns that are consistent with d 2 deformation microstructural study indicates the pluton recorded d 2 strain as it crystallized and cooled from the solidus demonstrating syn d 2 emplacement the results indicate the pervasive structural patterns in the sparrow pluton are an integral part of the regional strain field and that they are kinematically consistent with a transpressive d 2 strain regime mapping the fabric patterns within syntectonic plutons provides a useful approach to the kinematic analysis of synemplacement deformation events in multiply deformed metamorphic terranes

magnetic susceptibility variations in carbonates of the la vid group cantabrian zone nw spain related to burial diagenesis abstract the carbonates of the lower devonian la vid group in the cantabrian zone nw spain reveal distinct variations in low field magnetic susceptibility ms from base to top there is good correlation between ms variations and bulk fe content a predominance of paramagnetic minerals fe carbonate cements pyrite fe chlorite mainly responsible for these ms variations is evidenced by optical methods temperature dependent ms measurements and high field magnetisation behaviour these minerals are members of the diagenetic mineral assemblage formed during migration of a reducing fe bearing fluid we interpret the variation in ms to reflect two stages of fe bearing mineral precipitation with an earlier fe carbonate and a later fe chlorite crystallisation the latter restricted to interbedded carbonates and shales furthermore porosity has an additional influence on the ms signature with high values in coarse grained sandstones and carbonates and lower values in fine grained dolostones and limestones this study highlights the influence of diagenetic mineral formation on ms variations in carbonate bearing successions

first observations of polar mesosphere summer echoes in antarctica a 25 kw peak power 50 mhz radar was installed at the peruvian base on king george island antarctica 62 s in early 1993 a search for polar mesospheric summer echoes pmses was made during late january and early february of the first year of operation with negative results these results have been reported in the literature balsley et al 1993 1995 we report here results obtained during the austral summer of the second year 1994 of operation observations during the second year were begun earlier i e closer to the austral summer solstice pmses were observed during this period albeit the echoes were much weaker than what one would expect based on earlier poker flat radar results at a comparable latitude 65 n in the northern hemisphere a large and measurable asymmetry in pmse strength in the two hemispheres therefore exists we explain this asymmetry by postulating a difference in summer mesopause temperatures between the two hemispheres of 7 5 k this difference has been estimated using an empirical relationship between the variations of the poker flat pmse power as a function of temperature given by the mass spectrometer incoherent scatter extended msise 90 model

magnetic susceptibility of the rock matrix related to magnetic fabric studies non ferromagnetic minerals constitute what is called the rock matrix whose susceptibility k1 is directly accessible using only high magnetic fields measurements on minerals and a wide range of rock types show that k1 is mainly due to paramagnetism and hardly exceeds 10 3 si with an anisotropy degree p less than 1 35 different methods to estimate the role of the matrix component in low field susceptibility k and its anisotropy include petrological and chemical analysis evolution of p vs k low temperature studies and comparison of k with remanent magnetizations

transpressional tectonics during the emplacement of pasupugallu gabbro pluton western margin of eastern ghats mobile belt india evidence from ams fabrics abstract the pasupugallu gabbro anorthosite pluton intruded the transition zone between the mesoproterozoic eastern ghats granulites and the meso to paleoproterozoic amphibolites and migmatitic gneisses of east dharwar craton southern india the pluton is bound by shear zones at its entire eastern northern and southwestern margins the objective of this work is to study the internal fabric of the pluton to understand the tectonic setting during its emplacement essentially by means of anisotropy of magnetic susceptibility ams a total number of 107 samples have been subjected to ams and irm studies the magnetic fabric is principally ferromagnetic in origin as the magnetic susceptibility values are 10 3 si which is further supported by irm studies the magnetic fabrics correspond well with the field measurements and petrographic studies they show two lobes in both the northern and southern parts which display concentric inward dipping helicoidal foliation trajectories with interlayered steep and gently dipping domains the magnetic lineation pattern suggests that the magma might have ascended through the central lobes and extended towards outer margins particularly to the west the constrictional strains occur at the eastern margin while flattening strains mark the western margin ams studies together with our field structural observations suggest that the magma has been emplaced into a chamber dilational jog induced by crustal scale dextral transpressional tectonic regime probably during the onset of grenvilian event

horizontal and vertical zoning in the peruvian coastal batholith plutons of the coastal batholith of peru show both horizontal and vertical zoning in mineralogy and chemistry the horizontal variation is well seen in the areally extensive early tonalite superunits in which the sequence marginal quartz diorite tonalite adamellite granite is often seen this is the result of inward crystallization from the periphery of a relatively slowly cooling magma boundary layer convection combined with internal cell convection was effective in producing a markedly differentiated rest liquid the mineral assemblages are the result of incomplete separation of the evolved liquidus precipitate and the rest liquid in the smaller ring complex intrusions vertical variation is common and precipitation on the floor of the magma chamber resulted in the final crystallization of water rich aplites at the top in these later intrusions magma mixing and hybridization may also be important in both types of magma chamber stratification by boundary layer convection and diffusion seems likely to have complemented the conventional fractionation model of liquid evolution

emplacement and temporal constraints of the gondwanan intrusive complexes of northern patagonia la esperanza plutono volcanic case abstract two main lines of evidence disagree whether or not the patagonian blocks collided with gondwana all models invoke the voluminous magmatism of the la esperanza complex as evidence for active subduction magmatic arc or to a postcollisional setting the evolution of this bimodal igneous suite is reassessed with field geochronological shrimp u pb zircon and k ar mica and petrophysical data emplacement of high k calk alkaline granitic magmas occurred at shallow crustal levels 2 8 2 km depth related to the development and collapse of a caldera associated with a regional nw se structural trend magmatism involved intermediate hybrid pulses at 273 2 ma and 255 2 ma prieto granodiorite that shifted like a yo yo to acidic magmas at 260 2 ma and 250 2 ma donosa and calvo granites absence of solid state deformation features and the low anisotropy degrees in the granites indicate that its fabric is magmatic in origin magnetic fabric in granodiorites displays a concentrical pattern with subhorizontal foliations and lineations parallel to the volcanic axis magnetic foliations and moderately plunging lineations indicate a common feeder system for plutonics and volcanics donosa granite shows a discordant pattern with wnw ese ene wsw trending low plunging lineations and foliations the plutono volcanic system construction 273 255 ma followed nw se and ne sw diamond shape faults trends and supracrustal discontinuities magmatic climax is bracketed at 260 ma the collapse of the edifice is evidenced by the intrusion of acid magma plugs and dike swarms between 250 and 246 ma a similar age range was identified in other areas of patagonia related to syn and postcollisional tectonic events no evidence of tectonic activity such as major uplift metamorphism or thrusting was found excepting regional strike slip faulting and extension therefore la esperanza complex is a high crustal level episode and as such may not have structurally recorded an active collision during its crystallization and cooling

microstructure and magnetic susceptibility applied to emplacement kinematics of granites the example of the foix pluton french pyrenees abstract the variscan foix granite 40 km 2 central pyrenees was subjected to detailed microstructural magnetic susceptibility and anisotropy studies magnetic susceptibility is shown to be of dominant paramagnetic origin its magnitudes clearly define a zoning which compares with the petrographic zoning and reveals that the pluton is the southern remnant of a normally zoned pluton truncated during alpine tectonics magnetic susceptibility anisotropy characterizes the planar and linear preferred orientations of the main iron bearing silicates namely biotite and accessory amphibole it is argued that these fabrics also reflect the flow pattern of the granite microstructural observations aid in distinguishing the magmatic and late magmatic fabric signatures main body from the post magmatic solid state signature leucogranite in order to account for the consistently subhorizontal and ne sw directed magmatic lineations in the northern sector of the foix granite an oblique intrusion is proposed it may be coeval with the early variscan regional sw trending shearing event steepening of the structures in at least part of the southern sector may be coeval with the late development of upright folds and vertical cleavage in the country rocks the utility of combined microstructural and magnetic susceptibility studies is demonstrated as an aid in the structural interpretation of granite intrusions which act as kinematic markers of their host terranes

the maladeta granite polydiapir spanish pyrenees a detailed magnetostructural study abstract the maladeta granitic complex spanish central pyrenees has been subjected to a detailed magnetostructural study through the systematic measurement of magnetic susceptibility and anisotropy of magnetic susceptibility at 253 regularly spaced sampling sites due to the dominant paramagnetic property of the granites a first order correlation can be derived between the susceptibility magnitude and the bulk rock iron content hence the petrographic nature of the rock the maladeta complex is shown to be composed of four principal juxtaposed plutons each one being normally zoned i e becoming more basic towards the periphery the largest pluton namely the colomers unit is itself made of a number of sub plutons due to distinct but more or less coeval batches of magmas the various magnetic data complemented by field and microstructural observations allow us to propose that the maladeta polydiapir probably exploited ne and se trending openings of the brittle crust for its emplacement that accompanied or just preceded a sw verging compressive event a later n s compression marked by inverse dextral and e w trending shears is preferably attributed to late variscan rather than to alpine tectonics

intrusion level of granitic massifs along the hercynian belt balancing the eroded crust abstract hercynian granitoid intrusions form a long 3200 km belt comparable in size to other batholiths in the world six massifs have been selected which encompass cabeza de araya extremadura spain guitiriz galicia spain pontivy and mortagne brittany france la marche massif central france and fichtelgebirge bavaria germany detailed gravity surveys over these massifs and subsequent inversion provide their shape at depth correlation of the deeper zones with internal structures determine the place of the root zones the shape of the massifs is examined along the strike of the chain the emplacement of individual massifs is controlled by local tectonics most granites are not deeply rooted but one massif cabeza de araya spain shows a root zone presently as deep as 14 km most have about half of their volume in the first 3 km below the present surface estimates of the magma volume transferred result in 1500 km 3 issued from one specific feeder yielding a total of 70 000 km 3 of magma intruded all along the chain the depth of emplacement of the granitic massifs does not show any significant trend along the strike of the chain the shallower massifs in the french massif central correspond to more deeply eroded areas in the center of the chain their root zone as well as the change in the dip of the walls are presently observed at depths ranging between 4 and 6 km in hercynian granites both variations are interpreted as being related to the brittle ductile transition at the time of emplacement gross thermal considerations place the transition at its former place during magma emplacement indicating that the upper crust has not been eroded by more than 6 8 km this estimate severely contrasts with models involving a doubled crust

magnetic fabric and 3d geometry of the hombreiro sta eulaliapluton implications for the variscan structures of eastern galicia nw spain abstract in this paper the internal structure and 3d geometry of the hombreiro sta eulalia granitic pluton hercynian belt nwspain are described characterization of the internal structure was performed from surface data based on microstructural analysis and anisotropy of magnetic susceptibility studies the geometrical features of the pluton morphology at depth were derived from gravity data the pluton is made up of paramagnetic granites and leucogranites k values ranging between 1 1 and 13 3 10 5 si with well developed magnetic fabrics anisotropy degree p 1 05 for 78 of the sampling localities the results obtained enable us to depict a flat lying magnetic structure with associated n120 e trending magnetic lineations the gravity survey corroborates the subhorizontal laminar geometry of the pluton which has an estimated thickness of 2 km and an almost planar floor the 3d morphology is elongate at depth parallel to the linear internal fabric this would imply that magma emplacement took place along this preferential direction whereas the deepest zones of the pluton trend wnw ese elongate parallel to regional 1 it is almost rootless we present data showing that the hombreiro sta eulalia pluton emplacement was closely related spatially and chronologically along with other granitoid plutons from the lugo dome with two major structures of eastern galicia the basal shear zone of the mondonedo nappe and the extensional vivero fault

reply to comment on magnetic fabrics crystallographic preferred orientation and strain of progressively deformed metamorphosed pelites in the helvetic zone of the central alps quartenschiefer formation by carl richter lothar ratschbacher and wolfgang frisch

two day wave observations of uars microwave limb sounder mesospheric water vapor and temperature 1 a two day wave disturbance is observed in the mesospheric temperature and water vapor on the basis of new version data from the upper atmosphere research satellite microwave limb sounder using two data segments during the austral summers january february of 1992 and 1993 and the asynoptic mapping method a strong wave signal is identified as having zonal wave number 3 and a westward period of about 2 1 days the wave amplitudes are located near the core of the summer easterly jet with strongest wave amplitudes as large as 11 k and 0 35 part per million by volume near the mesopause the temperature and water vapor wave strengths are highly correlated in time but their peaks are almost longitudinally out of phase poleward heat flux associated with upward wave energy propagation in the southern hemisphere points to baroclinic instability as the cause for the wave appearance a growing wave signature in water vapor is observed in regions of strong meridional gradient of water vapor near the mesopause wave breaking is suggested as moist polar air is displaced into the much drier subtropics and wave amplitude decays

structure and u pb dating of the saint arnac pluton and the ansignan charnockite agly massif a cross section from the upper to the middle crust of the variscan eastern pyrenees in the agly massif pyrenees two variscan plutons the saint arnac pluton and the ansignan charnockite intrude different levels of a c 10 km thick crustal section the saint arnac pluton intrudes through upper crustal rocks and the ansignan charnockite cuts mid crustal country rocks a structural study of these plutons based on the anisotropy of magnetic susceptibility technique combined with a kinematic study of the country rocks shows that the structures and emplacement modes of the plutons are compatible with those of the other plutons of the pyrenees emplaced during the d 2 transpressive phase u pb dating on zircons from the saint arnac pluton yields a 308 3 1 2 ma age for a diorite and a 303 6 4 7 ma age for a granodiorite the charnockite was previously dated at 315 ma the emplacement ages of these two intrusions are thus separated by at least 5 ma first numerous sills and laccoliths such as the ansignan laccolith were injected in the middle crust and this induced heating and thickening subsequently the large saint arnac pluton was injected in the upper crust at the beginning of formation of a gneissic dome

the magnetic susceptibility of granitic rocks as a proxy for geochemical composition example from the saruhan granitoids ne turkey the magnetic susceptibility of rocks is determined by their bulk chemistry and magnetic mineralogy in this case study of the saruhan pluton in turkey a detailed survey based on 925 field measurements and 37 whole rock analyses reveals a strong correlation between magnetic susceptibility and feot r 2 0 8 petrographic observations and calculations based on whole rock major element analyses indicate the presence of magnetite grains further calculations show that magnetite accounts for 88 of the magnetic susceptibility the spatial correlation between feototal and the magnetic susceptibility is particularly spectacular which suggests that km is a proxy for geochemical differentiation the zoning pattern of magnetic susceptibility across the pluton is concentric and reverse with the highest values of magnetic susceptibility in the center this type of zoning is consistent with a previously proposed petrogenetic model the comparison of the saruhan granites with a classic example of paramagnetic granites reveals two contrasted feot km trends this suggests that these variations can be a useful tool to distinguish between leucocratic paramagnetic and leucocratic ferrimagnetic granites 2007 elsevier b v all rights reserved

southern hemisphere pmse where are they we report a surprising absence of pmse polar mesospheric summer echoes in vhf radar observations of the southern summer high latitude mesosphere our observations cover about twenty days during january february 1993 from king george island antarctica

changes in vegetation type on the chinese loess plateau since 75 ka related to east asian summer monsoon variation abstract floral communities in terrestrial habitats such as steppes are highly sensitive to regional climate changes here we generated carbon and nitrogen isotope profiles for soil organic matter som in the weinan loess paleosol section in order to investigate changes in floral communities on the chinese loess plateau clp and their relationship to climate variation since 75 ka 13csom at weinan ranges from 23 6 to 18 0 and 15nsom ranges from 3 4 to 5 5 modeling based on the 13csom record suggests that the proportion of c4 plants c4 has varied from lower during cold intervals with minima of 24 32 at 73 1 ka 20 9 ka lgm and 0 6 ka to higher during warm intervals with maxima of 62 64 at 53 0 ka and 8 2 ka the 13csom and 15nsom profiles are strongly correlated r 0 82 p

zonal wave numbers of the summertime 2 day planetary wave observed in the mesosphere by eos aura microwave limb sounder 1 recent observations and theoretical work suggest that the 2 day planetary wave in the summertime mesosphere is composed of multiple superposed zonal wave numbers here we use eos aura microwave limb sounder mls temperature data to determine the component zonal wave numbers of the 2 day wave in the mesosphere at latitudes of 70 s to 70 n from 2004 to 2009 we consider the effect of aliasing between different wave numbers and note that significant aliasing can occur and result in spurious signals particularly at high latitudes in winter the seasonal evolution of the different wave numbers is investigated and found to be very different between the northern and southern hemispheres in both hemispheres the wave is dominated by westward traveling waves of zonal wave number 3 and 4 w3 and w4 however in the southern hemisphere the wave is dominated by the w3 component but in the northern hemisphere the w3 component is smaller and the w4 component is often of similar or larger amplitude a small amplitude westward traveling zonal wave number 2 w2 wave is also evident in both hemispheres in the northern hemisphere the w2 amplitudes never exceed 3 k the w3 amplitudes can reach 3 5 k and the w4 can be the largest component reaching amplitudes of 4 k in the southern hemisphere the w2 amplitudes can reach up to 3 5 k the w3 amplitudes can be much larger reaching 12 k and the w4 amplitudes are smaller than in the northern hemisphere in 4 out of 5 years not exceeding 3 k the northern hemisphere w4 can reach large amplitudes in august when the w3 is small which means that the late summer northern hemisphere quasi 2 day wave is usually a w4 oscillation rather than the familiar w3 in contrast in the southern hemisphere the w3 is often larger than the w4 around the summer solstice and there are no episodes observed where the wave becomes dominated by the w4 for an extended period of time a high degree of interannual variability is evident particularly in the southern hemisphere where the w3 peak amplitudes vary from 12 k in january 2006 to 3 k in january 2009 the height latitude structure of the w4 suggests that this wave is a 4 0 rossby gravity wave

geochemical and isotopic constraints on petrogenesis the serra da freita pluton a typical granite body from the portuguese hercynian collision belt the hercynian serra da freita pluton in north central portugal is emplaced within a sillimanite bearing flychoid sequence of graywackes and pelitic schists here tested as a possible protolith for the granite there is a marked overlap in most major element values between the schists and the granite however high k values preclude anatexis of pelite and the 3 fold na enrichment shown by the granites could be achieved by 25 30 partial melting of immature graywacke depletions of ba nb ce zr ti and y in the granite reflect retention of these elements in the source restite separation may have occurred to some limited extent however enrichment in rb may be due to late stage fractional crystallization overlapping 18 o values for both schists and granites at 10 to 14 combined with an initial 87 sr 86 sr of 0 7136 for the pluton strongly support the local graywacke rich beira schists as the most likely protolith for this strongly peraluminous granite magma

magnetic mineralogy of some granites from the french massif central origin of their low field susceptibility abstract with a view to a better understanding of the origin of the low field susceptibility in the variscan granitoids of the french massif central for which extensive structural mapping using the anisotropy of magnetic susceptibility ams technique is currently applied a detailed study of magnetic carriers has been undertaken origin of the susceptibility has been studied using high field and low temperature measurements in a cryogenic magnetometer together with standard rock magnetic techniques additional determinations of the opaque phases have been performed with the metallographic microscope x ray microdiffraction and electron microprobe techniques in almost all the granite types the magnetic susceptibility is essentially carried by the paramagnetic biotite crystals minor amounts of ubiquitous oxides ilmenite rutile titano haematite do not contribute significantly to the susceptibility this is also the case for rare occurrences of magnetite in some granitoids mainly the cordierite bearing anatexites sulphides are found to give a large contribution magnetic mineralogy identifies a mixture of ferromagnetic pyrrhotite and antiferromagnetic fe9s10 hexagonal pyrrhotite hpo the latter species is identified as forming the larger unaltered pyrrhotite grains the ferromagnetic pyrrhotite is identified to be mainly smythite fe9s11 a species formed by supergenic alteration of monoclinic pyrrhotite located along the basal cleavage planes the microfractures and the grain boundaries of the hpo this study which constitutes the first report of the magnetic properties of smythite in rocks indicates that magnetic carriers derived from low temperature alteration have to be taken into account for purposes of structural studies using ams

magnetic susceptibility of the mont louis andorra ilmenite type granite pyrenees a new tool for the petrographic characterization and regional mapping of zoned granite plutons we have observed remarkably consistent patterns of concentric zonation in the values of low field magnetic susceptibility measurements over the variscan age mont louis andorra granite pluton of the eastern pyrenees of andorra spain and france this zonation is a function of the rock petrology since a close correlation is shown between the petrographic nature as defined by chemical analysis and the magnetic susceptibility magnitude of the rocks it reflects the dominantly paramagnetic nature of the granite carried by fe bearing silicates and this is demonstrated by the fact that low field susceptibilities of representative specimens are almost equal to 1 their high field susceptibilities and 2 their calculated susceptibilities using fe contents assuming a null ferromagnetic contribution we conclude that this technique accurately reflects the modal abundances of ferromagnesian phases in rocks of the ilmenite series and that it represents a powerful and efficient tool for the reconnaissance surveying of petrological variations in granitoid plutons

main results of the ecors pyrenees profile abstract the 250 km long deep seismic reflection survey across the pyrenees from one foreland ebro basin to the other aquitaine basin was designed to study the structure of the deformed mesozoic boundary between the iberian and european plates the results are 1 1 the entire crust shows well defined reflectors with a general fan shape geometry 2 2 a deep layered domain is evident above the moho discontinuity 3 3 near the surface in the external domains reflectors accurately define the geometry of major thrusts and structures affecting the mesozoic and cenozoic cover of the pyrenees 4 4 the middle crust shows two major sets of seismic events interpreted as hercynian structures using these results a balanced structural section of the pyrenean belt is proposed the mode of thickening of the crust during the alpine orogeny is briefly discussed only the iberian crust was significantly thickened by a southward stacking of slabs

submarine hydrothermal processes mirroring the geotectonic evolution of the ne hungarian jurassic szarvaskő unit the jurassic pillow basalt of the ne hungarian szarvask unit is part of an incomplete ophiolitic sequence formed in a back arc or marginal basin of neotethyan origin different often superimposing hydrothermal processes were studied aiming to characterise them and to discover their relationship with the geotectonic evolution of the region closely packed pillow pillow fragmented hyaloclastite breccia and transition to peperitic facies of a submarine lava flow were observed the rocks underwent primary and cooling related local submarine hydrothermal processes immediately after eruption at ridge setting physico chemical data of this process and volcanic facies analyses revealed distal formation in the submarine lava flow a superimposing more extensive fluid circulation system resulted in intense alteration of basalt and in the formation of mostly sulphide filled cavities this lower temperature but larger scale process was similar to vms systems and was related to ridge setting as a peculiarity of the szarvask unit locally basalt may be completely altered to a grossular bearing mineral assemblage formed by rodingitisation s l this unique process observed in basalt happened in ridge setting during spreading in the absence of known large ultramafic blocks epigenetic veins formed also during alpine regional metamorphism related to subduction obduction the observed hydrothermal minerals represent different steps of the geotectonic evolution of the szarvask unit from the ridge setting and spreading till the subduction obduction hence studying the superimposing alteration mineral assemblages can be a useful tool for reconstructing the tectonic history of an ophiolitic complex though the found mineral parageneses are often similar careful study can help in distinguishing the processes and characterising their p t and x conditions

properties of the quasi 16 day wave derived from eos mls observations 1 this paper describes the use of eos microwave limb sounder mls data to observe the field of traveling planetary waves with quasi 16 day periods this study utilizes mls v2 2 temperature and geopotential data between 1 january 2005 and 31 december 2008 in the range 316 hpa to 0 001 hpa approximately 8 to 97 km to examine these waves analysis demonstrates that the quasi 16 day wavefield is made up of a number of components with westward and eastward propagating s 1 and s 2 waves generally dominant in the northern hemisphere the westward and eastward propagating s 1 waves have similar magnitudes and are larger than the other modes while in the southern hemisphere the eastward propagating s 1 and s 2 waves are larger than the westward propagating wave modes all of the modes examined display strong seasonal patterns in the temperature amplitude significant variability in the wave activity from year to year and the presence of strong pulse like patterns in the activity all of the modes also display large median temperature amplitudes poleward of 40 degrees in both hemispheres our analysis also demonstrates that the variability in winter from year to year is larger in the northern hemisphere than the southern hemisphere detailed study also suggests that the exclusion of waves from regions of negative refractive index squared likely forms much of the seasonal pattern observed thus regions of strong westward wind speeds effectively exclude vertically propagating waves as expected from theory the reflection and absorption of waves associated with critical lines is also likely to explain the frequent occurrence of standing wave patterns in the eos mls temperature observations this study highlights the potential of mls observations for observing waves from the upper troposphere to the lower mesosphere

the pan african toro complex northern nigeria magmatic interactions and structures in a bimodal intrusion the toro complex is one of the pan african older granites of nigeria first described as a reversely zoned pluton made of a central dioritic mass surrounded by a broad granitic rim it has been thoroughly reinvestigated both from the petrographic and structural points of view with the help of systematic anisotropy of magnetic susceptibility ams measurements the granite main body is a hornblende biotite porphyritic monzogranite characterized by an early submagmatic fabric displaying a concentric pattern of foliations and west plunging lineations stage 1 this fabric is overprinted by a later one due to solid state strain along north south subvertical dextral shear zones stage 2 in the vicinity of the diorite an evengrained granite displays magmatic structures that are contemporaneous with this strike slip event the diorite granite contact is a complex zone where field petrographic and geochemical data enable recognition of the effects of mixing and mingling between a mafic and a felsic magma tonalites cropping out within this contact zone are interpreted as hybrid rocks the reverse zonation of the diorite itself is also the result of some hybridization process magmatic interactions mainly resulted from in situ infiltration of granitic liquid into the dioritic mass the detailed history of this bimodal intrusion began with the emplacement of the granitic magma acquiring a first stage fabric before full crystallization of the granitic core intrusion of the dioritic magma permitted reheating of the granitic magma that then crystallized with specific structural characters the second stage structures whether characterized by magmatic fabric near the diorite or by solid state strain features in north south shear zones elsewhere in the granite are related to late pan african dextral strike slip tectonics in the basement of northern nigeria the bimodal toro complex is therefore considered as a late pan african syntectonic pluton

inversion tectonics and magnetic fabrics in mesozoic basins of the western tethys a review abstract positive tectonic inversion of sedimentary basins has been recognized as one of the primary mechanisms of mountain building and intraplate deformation reconstructing the tectonic history of basins is relatively easy for the inversion stage but becomes more difficult for the basinal stage especially when strong deformation involving cleavage development is associated with the subsequent compressional tectonics since tectonic markers for the extensional episodes are not commonly well developed anisotropy of magnetic susceptibility ams has provided recently a tool for analyzing early stages in the evolution of sedimentary basins even in the absence of other outcrop scale mesostructures here we expose and discuss the applicability of magnetic fabrics by means of ams to different types of intra plate sedimentary basins in the western tethys region formed under extensional or transtensional regimes and which underwent different inversion styles total or partial inversion with or without cleavage development forming part of compressional thrust sheets etc owing to specific particular p t conditions and structural controls factors such as lithology magnetic mineralogy position within the sedimentary pile and deformation intensity are key to interpret the obtained magnetic fabrics in terms of tectonic evolution a basin classification is proposed according to inversion styles and magnetic fabrics where inversion did not involve cleavage development magnetic lineation is parallel to the stretching direction corresponding to the extensional stage the transition between non cleaved to inversion related cleaved units is marked by the switch of magnetic lineations from parallel to extension to parallel to the intersection lineation between cleavage and bedding these relationships are enhanced when extension and compression are roughly coaxial then favoring the clustering of axes of the magnetic ellipsoid even when extreme inversion occurs and the early extensional fabric is obliterated magnetic fabrics provide information about the interaction between preferred deformation directions associated with the main stages in basin evolution

an eastward propagating two day wave evidence for nonlinear planetary wave and tidal coupling in the mesosphere and lower thermosphere 1 temperature observations from the saber instrument on the timed spacecraft are used to investigate the structure and evolution of an eastward propagating zonal wavenumber 2 disturbance with a period near two days this oscillation obtains a maximum amplitude of nearly 10 k in the southern hemisphere mid latitudes during late january the timing and location of this planetary wave is coincident with the regular quasi two day wave intensification that occurs annually in late january the period wavenumber and spatial structure of the eastward propagating two day wave are consistent with a wave that results from a nonlinear interaction between the quasi two day wave and the migrating diurnal tide the existence of an eastward propagating wave with a period near two days coincident with the westward propagating two day wave will have an impact on the interpretation of ground based observations analysis of the saber temperature observations are utilized to determine the structure and evolution of both this eastward propagating two day wave and the classic westward propagating zonal wavenumber 3 quasi two day wave during january 2005

low latitude 2 day planetary wave impact on austral polar mesopause temperatures revealed by a january diminution in pmse above davis antarctica 1 a new characteristic of the austral summer polar mesopause as revealed by ground based radar and satellite temperature measurements is reported that is linked to inter annual variability of the low latitude easterly wind jet four consecutive seasons of polar mesosphere summer echoes pmse and mesosphere temperature observations above davis antarctica 68 6 s show a mid january diminution in pmse occurrence rate that coincides with a minor mesopause warming of several degrees spectral analyses of pmse aura microwave limb sounder mls temperatures and radar meridional winds show the presence of 4 5 day planetary waves pws throughout the austral summer in the polar upper mesosphere together with enhanced 2 day pw activity from mid january to mid february analysis of mls temperatures show that the 2 day pws have zonal wavenumbers s with both westward s 2 3 and eastward s 2 3 components although displaying some inter annual variation in the peak onset time the mid january mesopause warming coincides with a weakening of the equatorward meridional wind above davis and enhancement of low latitude 2 day pw activity

emplacement of the aya variscan granitic pluton basque pyrenees in a dextral transcurrent regime inferred from a combined magneto structural and gravimetric study magmatic structure three dimensional shape and emplacement mode of the aya pluton variscan pyrenees have been studied by combining magneto structural and gravimetric studies the aya pluton displays a fabric acquired using the anisotropy of magnetic susceptibility technique comparable to that of several other plutons in the pyrenees with shallow plunging lineations and steep foliations trending e w and ne sw forming an s pattern in map view gravity modelling was used to determine the probable root of the pluton directly below the most basic gabbro dioritic facies this has a funnel shape with an e w trending elliptical horizontal section and a maximum depth of 3 5 km these different data demonstrate that this pluton was synorogenically emplaced during the main d2 variscan tectonic phase in a dextral transcurrent regime

the gangotri granite garhwal himalaya laccolithic emplacement in an extending collisional belt the gangotri miocene leucogranite is composed of several laccoliths 6 7 km long 1 5 2 km thick which can be divided into two sets of lenses the southern lenses intruded in the lower part of the high himalaya sedimentary cover and the northern lenses intruded in an older porphyritic biotite bearing granite in both cases the magmatic fabric is commonly weak with no dominant stretching direction although a rough e w trend is present in the northern lenses the magnetic fabric is characterized by the fact that drastic changes in the direction in the magnitude of the magnetic parameters or in the fabric type planar or linear may take place over very short distances measurements of preferred orientations in thin sections indicate that the strain regime was largely dominated by a coaxial component for both sets of lenses in agreement with the large dispersion observed in both the field and magnetic lineations the comparison of the granite and host rock structures shows that the leucogranite emplacement dates the onset of the extensional tectonism in the high himalaya range and is not related to a southward directed thrust event associated with the main central thrust this is exemplified by the vertical attitude of the feeder dikes that intrude the metasedimentary rocks beneath die southern lenses the presence of these dikes indicates in turn that magma ascent occurred by fracture propagation the spatial disposition of the southern lenses could have resulted either from the disruption of a single laccolithic intrusion by crustal scale boudinage due to a northern gravity backslide of the top of the tibetan slab or from the intrusion of independent laccoliths the use of the elastic bending theory of pollard and johnson 1973 shows that in both hypotheses the current laccolith sizes are compatible with a laccolithic mode of magma emplacement however neither the density contrast between the magma and its enclosing rocks nor the lithological boundary between the tibetan slab and the overlying tibetan metasedimentary series controlled the level of magma emplacement rather flat lying collapse structures which intersected the upward propagating magma dikes are the most likely causes of magma arrest such a mechanism was favored by the schist rich lithology of the metasedimentary host rocks in addition field relationships indicate that the melt supply through the dike system was a continuous rather than pulsed process existing numerical treatments on the rates of magma transport through fractures show that in such a case the laccoliths could have been built in less than 100 years this short time of emplacement the small size of the laccoliths and their peripheral disposition relative to the badrinath granite suggest that the gangotri lenses may represent the initial stage of pluton accretion in the high himalaya which ultimately gave rise to a much larger massif such as the manaslu granite

internal fabric and strike slip emplacement of the pan african granite of solli hills northern nigeria the solli hills pluton 250 km2 in northern nigeria is an example of a pan african granite emplaced circa 580 ma ago in the jos adamawa block its micro structures and internal fabrics have been studied in order to help constrain the kinematics of the pan african orogeny in this block we used field observations and measurements petrographic examinations and measurements of the magnetic susceptibility and anisotropy of magnetic susceptibility of 124 regularly spaced stations most samples are ferromagnetic i e belong to the magnetite series granites and present predominantly magmatic microstructures particularly remarkable are the asymmetrical zoning of the petrographic types the susceptibility magnitudes and the planar linear magnetic fabrics the magnetic foliations and lineations are very consistent in the pluton around n 20 e 60 w and n 205 e 10 respectively field and microscopic observations reveal that deformation occurred everywhere in the pluton and immediate country rock envelope during a dextral strike slip synplutonic episode it is suggested that the solli hills pluton was emplaced in a late pan african dextral tear fault system the striking fabric asymmetry of the pluton strongly suggests a shear zone termination emplacement model

gravimetric and magnetic fabric study of the sintra igneous complex laccolith plug emplacement in the western iberian passive margin the geometry and emplacement of the 96 km2 late cretaceous sintra igneous complex sic ca 80 ma into the west iberian passive margin is presented based on structural data gravimetric modeling and magnetic fabrics a granite laccolith 76 km2 1 km thick according to gravimetric modeling surrounds a suite of gabbro diorite syenite plugs 20 km2 4 km deep and is encircled by cone sheets and radial dykes anisotropy of magnetic susceptibility was interpreted from 54 sites showing fabrics of para and ferro magnetic origin most fabrics can be interpreted to have a magmatic origin according to the scarcity of solid state deformation in most part of the massif magnetic foliations are shallowly dipping in the granite laccolith and contain a sub horizontal ene wsw lineation the gabbro syenite body displays concentric magnetic foliations having variable dips and steeply plunging lineations the sic can be interpreted to be intruded along an nnw sse 200 km long fault perpendicular to the magnetic lineation within the laccolith and was preceded by the intrusion of basic sills and plugs the sic intruded the mesozoic series of the lusitanian basin during the post rift passive margin stage and its geometry was only slightly modified during the paleogene inversion that resulted in thrusting of the northern border of the intrusion over the country rocks

the tourmaline bearing granite pluton of bodmin cornwall uk magnetic fabric study and regional inference the magnetic fabrics and microstructures of the variscan granite pluton of bodmin cornwall have been studied its low susceptibility magnitude consistent with its lack of magnetite comes from biotite and tourmaline as the magneto crystalline behaviour of tourmaline is inverse compared with that of the phyllosilicates the magnetic fabric was remeasured after heating the specimens to enhance the biotite magnetic signal by the growth of mimetic magnetite the roughly similar magnetic fabrics before and after heating demonstrate that the effect of tourmaline is not important as long as the tourmaline content does not exceed that of the phyllosilicates regionally this study reveals a well defined nnw trend of the magnetic lineations with opposite plunges on each side of a separation line crossing the pluton centre this pattern very similar to that documented in the nearby carnmenellis pluton is ascribed to unroofing during emplacement it agrees with the late to post magmatic nw stretch that characterizes the devonian to carboniferous formations located to the north of this region the thrust and fold structure of which is attributed to southward compression we conclude that syntectonic emplacement may have characterized the whole cornubian batholith at the very end of the variscan orogeny in cornwall

a dynamic model of the structural evolution of the hercynian pyrenees abstract the structural history of the hercynian pyrenees is considered with respect to the relationships between the metamorphism and the successive deformations the characteristics and mode of emplacement of the gneissic and anatectic cores of the metamorphic domes the migmatization and the intrusions of plutonic and basic and ultrabasic rocks the metamorphism can be shown to have progressed upwards with time attaining the presently exposed levels just before during and a short time after the major penetrative regional deformation the intrusion of major plutonic anatectic and gneissic massifs which has determined the metamorphic domes in country rocks was roughly synchronous with the progression of the metamorphism but seems to have continued later in the uppermost levels the basic and ultrabasic rocks uplifted by the intrusion of the anatectic cores of the metamorphic domes have been deformed and foliated by the major regional penetrative deformation thus showing that their intrusion predated this deformation in the lowermost levels these results together with the presently available sedimentological data lead us to propose a dynamic model of the tectonic evolution of the hercynian pyrenees the first step was a crustal extension and thinning attaining its maximum during frasnian time marked in the upper levels by a horst and graben controlled sedimentation and in the lower crust by intrusions of basic magmas and the onset of the very low pressure metamorphism and anatexis characteristic of the hercynian pyrenees the second step was a crustal shortening marked by large scale crustal thrusting followed by widespread regional penetrative deformation the flysch troughs formed in front of the progressing and emerging thrusts in lower levels the thrusts are believed to have controlled the progressive ascent of the plutonic and anatectic magmas which continued their uplift and emplacement during major penetrative regional deformation in the actual mesozone and probably after it in the uppermost levels

magnetic fabrics in the cabanas granite ne brazil interplay between emplacement and regional fabrics in a dextral transpressive regime the late neoproterozoic cabanas granite northeastern brazil is a tabular body that was emplaced south of the dextral east pernambuco shear zone system anisotropy of magnetic susceptibility ams measurements reveal that the cabanas granite has fabric patterns more complex than usually reported in plutons intruded in similar settings most structures have ew to ene trending magnetic lineations consistent with the overall regional structural direction in the north these structures parallel the mylonitic fabric encountered in shear zones that bound or cross cut the pluton in the central and southern portions of the pluton magnetic foliation trajectories the overall banded disposition of the iso susceptibility lines and shape parameters of the ams ellipsoids suggest that the cabanas granite was subjected to ene trending folding along with its underlying and enclosing country rocks it is concluded that emplacement took place during regional dextral transpression a secondary but well developed family of structures consists of n to nw plunging lineations which is interpreted to represent the trace of the vertical conduits that fed the pluton this study emphasizes the utility of the ams to unravel both the internal structure of low anisotropy plutons and the interplay between emplacement and regional straining during magma crystallization

lidar observations of persistent gravity waves with periods of 3 10 h in the antarctic middle and upper atmosphere at mcmurdo 77 83 s 166 67 e persistent dominant and large amplitude gravity waves with 3 10 h periods and vertical wavelengths 20 30 km are observed in temperatures from the stratosphere to lower thermosphere with an fe boltzmann lidar at mcmurdo antarctica these waves exhibit characteristics of inertia gravity waves in case studies yet they are extremely persistent and have been present during every lidar observation we characterize these 3 10 h waves in the mesosphere and lower thermosphere using lidar temperature data in june from 2011 to 2015 a new method is applied to identify the major wave events from every lidar run longer than 12 h a continuous 65 h lidar run on 28 30 june 2014 exhibits a 7 5 h wave spanning 60 h and 6 5 h and 3 4 h waves spanning 40 and 45 h respectively over the course of 5 years 323 h of data in june reveal that the major wave periods occur in several groups centered from 3 5 to 7 5 h with vertical phase speeds of 0 8 2 m s these 3 10 h waves possess more than half of the spectral energy for 93 of the time a rigorous prewhitening postcoloring technique is introduced for frequency power spectra investigation the resulting spectral slopes are unusually steep 2 7 below 100 km but gradually become shallower with increasing altitude reaching about 1 6 at 110 km two dimensional fast fourier transform spectra confirm that these waves have a uniform dominant vertical wavelength of 20 30 km across periods of 3 5 10 h these statistical features shed light on the wave source and pave the way for future research

anisotropy of magnetic susceptibility as a strain gauge in the flamanville granite nw france the relationship between strain and anisotropy of magnetic susceptibility ams has been investigated in the carboniferous flamanville granite in the armorican massif nw france we measured the axial ratios of elliptical inclusions and the orientation of cleavage planes at eight sites around the granite margin measurements of ams were made on 73 specimens using a schonstedt spinner magnetometer ams measurements are shown to provide accurate predictions of cleavage and lineation direction even where these structures are difficult to measure in the field the strain and ams ellipsoids show similar regional variations in shape and intensity and a good correlation between the lengths of the principal axes finally our data are consistent with the hypothesis that the flamanville granite was syntectonically emplaced during the late stages of the hercynian orogeny

magmatic structures and kinematics emplacement of the variscan granites from central portugal serra da estrela and castro daire areas abstract the late d3 variscan granites which represent the most important volume of granites of central portugal are studied here for their magmatic and solid state fabrics by means of the anisotropy of magnetic susceptibility ams technique in a 5000 km 2 area located between guarda and castro daire including the serra da estrela region two main directions n150e and n20e of stretching lineations are found indicating that the emplacement of these late kinematic granitoids was tectonically controlled a three stage model is proposed in which a openings along n150 striking dextral strike slip faults allow the first granitic magmas to be emplaced in the upper crust of palaeozoic metasediments and syn d3 granitoids b openings along n20 striking possibly sinistral strike slip faults conjugates to the prior strike slip faults and allow the enlargement of the granitic plutons and c the final emplacement of this huge volume of granitic rocks was mainly controlled by the magma pressure which explains the rarity of structures related to this stage of granites emplacement in the country rocks this structural study of granitic rocks yields new constraints on the tectonic evolution of this part of the variscan orogenic belt at c 300 ma

study on finite strain and its relationship with magnetic fabric along ailao shan red river shear zone 1 the finite strain along ailao shan red river shear zone has been studied the axial ratios of strain markers and shear strains vary greatly arising principally from deformation intensity and from contrasting competencies ellipticity of chloritic amygdales in basalt ranges from 6 79 to 10 47 corresponding shear strain gamma xz 2 22 2 93 and ellipticity of garnets from 1 56 to 2 95 gamma xz 0 45 1 14 in core gneiss the s c angle of the sheared rocks varies from 2degrees to 28degrees gamma sc 1 35 28 60 mostly in a range 2degrees to 7degrees optical observation thermal demagnetization and hysteresis curves were conducted to determine the nature of minerals and the contribution of paramagnetic and ferromagnetic minerals to magnetic susceptibility the result shows that ferromagnetic minerals and hornblende dominate the magnetic fabric of samples with high to very high susceptibility and play an important role in the magnetic fabric of samples with low to intermediate susceptibility the ferromagnetic minerals are mainly pseudo single domain and multidomain ti poor magnetite most samples have their magnetic lineation lying between the c and s surfaces in the remaining samples deviations from this common alignment principally resulted from the magnetic minerals being deflected by porphyroclasts mineral cleavage and cracks the axial ratio correlation is very poor between the magnetic and actual or imaginary strain ellipsoid calculated from the s c fabric this poor correlation suggests that the shape of the finite strain ellipsoid cannot be evaluated using the magnetic fabric when the latter is a combined result from multiple minerals and especially when the shape effect of multidomain titanomagnetite is important

first southern hemisphere common volume measurements of pmc and pmse 1 using rayleigh lidar and mesosphere stratosphere troposphere radar at davis antarctica 68 6 s during the 2005 2006 austral summer we obtained the first southern hemisphere common volume measurements of polar mesospheric clouds pmc and polar mesosphere summer echoes pmse pmc were observed with 6 probability during 349 hours of lidar observations pmse were simultaneously observed during 70 of the pmc events the mean centroid altitudes of simultaneous pmc and pmse were 83 97 0 10 km and 85 31 0 14 km respectively the altitude difference 1 3 km is comparable to earlier boreal common volume measurements both phenomena show clear diurnal variations in altitude and occurrence pmc had a unimodal local time occurrence distribution which peaked 4 6 hours after solar midnight pmse were most prevalent at this time but had a secondary occurrence peak 6 hours after solar noon when pmc were absent we explain the altitude time distributions of pmc and pmse in terms of the thermal structure of the mesopause region determined using measurements from the aura satellite

magnetic susceptibility and partial anhysteretic remanence anisotropies in the magnetite bearing granite pluton of tourao ne brazil abstract rock magnetism and magnetic fabric studies were performed in the tourao granite western part of serido belt ne brazil this pluton 350 km2 is composed of k rich calc alkalic monzogranites and was emplaced between a set of ne and e trending dextral strike slip shear zones electronic and optical microscopy thermomagnetic curves hysteresis data and coercivity spectra revealed that magnetite fine and coarse grained is the unique ferromagnetic mineral in these rocks anisotropy of low field magnetic susceptibility ams was measured in 83 sites and for many sites from central and southern parts of the intrusive body a large scatter was noticed anisotropy of partial anhysteretic remanence paar was determined for 29 sites in the 0 50 mt paar0 50 and 19 sites in the 50 90 mt paar50 90 windows to isolate the fabric contribution of the remanence bearing grains magnetite in most sites ams is dominantly carried by magnetite whereas in some sites the paramagnetic contribution exceeds 60 of the bulk susceptibility the paar0 50 is assumed to be related to coarse grained early crystallized magnetites while the paar50 90 is interpreted as due to fine needle shaped magnetites hosted in biotites the combined analysis of these magnetic techniques permits interpretation in terms of fabric formation in the tourao granite and the inference that at least two successive kinematic events were recorded in this intrusive body devoid of any solid state deformation overprint the ams and paar0 50 fabrics for most of the sites correlate with the early nne trending magmatic fabric whereas paar50 90 reveals a different fabric probably related to late partitioning of magmatic straining along the e trending shear zones in the southern part of the body a completely different paar0 50 fabric is correlated with the late intrusion of charnockite stocks

the shir kuh pluton central iran magnetic fabric evidences for the coalescence of magma batches during emplacement abstract the 136 ma nw se elongate shir kuh pluton is one of the most poorly understood geological feature of central iran it is composed of peraluminous rocks corresponding to ilmenite bearing s type granites compositionally ranging from granodiorites to leucogranites these rocks show a continuum in their chemistry attributed to progressive differentiation this allows using the anisotropy of magnetic susceptibility technique to tempt establishing the relative chronology between emplacements of magma batches in the pluton the rather low susceptibility magnitudes km