a ground motion predictive model for iran and turkey for horizontal pga pgv and 5 damped response spectrum investigation of possible regional effects we present a ground motion prediction equation gmpe for turkey and iran to investigate the possible regional effects on ground motion amplitudes in shallow active crustal earthquakes the proposed gmpe is developed from a subset of the recently compiled strong motion database of the earthquake model of the middle east region project see data and resources 1 a total of 670 turkish and 528 iranian accelerograms with depths down to 35 km are used to estimate peak ground acceleration peak ground velocity and 5 damped elastic pseudospectral acceleration ordinates of 0 01 s t 4 s the moment magnitude range of the model is 4 m w 8 and the maximum joyner boore distance is r jb 200 km the functional form considers three major fault mechanisms strike slip normal and reverse the nonlinear soil behavior is a function of v s 30 average shear wave velocity in the upper 30 m of soil profile our observations from empirical and estimated ground motion trends advocate regional differences in the territories covered by iran and turkey that originate from the differences in q factors kappa and near surface velocity profiles these factors eventually affect the magnitude and distance dependent scaling of spectral amplitudes in iran and turkey in essence the ground motion amplitudes of these two neighboring countries would draw patterns different than the ground motion estimates of gmpes developed from the strong motion databases of shallow active crustal earthquakes from multiple countries online material matlab code and regression coefficients for computing the response spectrum and distance scaling 1 sec 7

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

behavior of near source peak horizontal and vertical ground motions over smart 1 array taiwan abstract over 700 accelerograms recorded from 12 earthquakes in northeast taiwan have been analyzed for investigating the behavior of vertical and horizontal peak and spectral ground motion in the near source region peak horizontal and vertical ground acceleration pga velocity pgv and displacement pgd in the range of engineering interest have been subjected to a two step nonlinear regression procedure in terms of magnitude and hypocentral distance in comparison with a number of other studies of global pga observations our predictions show lower far field attenuation lower near source amplitudes higher magnitude saturation for the vertical component lower magnitude saturation for the horizontal component and higher magnitude scaling the 2 3 ratio of vertical to horizontal ground motion commonly used in engineering applications may be unconservative in the very near field for high frequency ground motion it falls below 1 2 at distances greater than 50 km the same ratio for pgv and pgd tends to increase with distance the latter at a faster rate for smart 1 data the major source of uncertainty appears to be inter event rather than intra event randomness the predominance of the inter event uncertainty in ground motions near the source is expected to be a characteristic of all dense arrays

magnetic fabric of the barrington passage pluton meguma terrane nova scotia a two stage fabric history of syntectonic emplacement abstract structural analysis and the anisotropy of magnetic susceptibility ams are used to document the internal magmatic to high temperature subsolidus fabrics of the tonalitic late devonian barrington passage pluton the ams fabric orientations compare favorably with mesoscopic scale fabrics in general the k1 k2 principal plane of the ams is close to the observed mineral foliation defined by biotite and plagioclase and the k1 axis is aligned parallel to a mineral lineation defined by the same minerals and to a locally developed weak extension lineation defined by quartz measurement of the anisotropy of anhysteretic remanence aar and image analysis of biotite preferred orientations confirm that the orientation of the ams is principally controlled by biotite locally anomalous ams orientations are attributed to the influence of fine grained magnetite crystals the presence of which is revealed by measurements of hysteresis and coercivity properties a two stage fabric history is revealed first horizontal fabrics were formed foliation compositional banding during emplacement of a laccolith like pluton the second stage involved synmagmatic folding of the horizontal foliation and banding in response to regional contraction associated with the acadian orogeny with development of a lineation that records stretching parallel to the fold axis the results demonstrate that the barrington passage pluton was emplaced during the main phase of the acadian orogeny a model is proposed that depicts the barrington passage pluton as the folded base of a larger syntectonic pluton that is now largely eroded off

emplacement mechanism of the main granite pluton of the lavras do sul intrusive complex south brazil determined by magnetic anisotropies abstract magnetic fabric and rock magnetism studies were performed on apparently isotropic granite facies from the main intrusion of the lavras do sul intrusive complex pluton lsic rio grande do sul south brazil this intrusion is roughly circular 12 13 5 km composed of alkali calcic and alkaline granitoids with the latter occupying the margin of the pluton magnetic fabrics were determined by applying both anisotropy of low field magnetic susceptibility ams and anisotropy of anhysteretic remanent magnetization aarm the two fabrics are coaxial the parallelism between ams and aarm tensors excludes the presence of a single domain sd effect on the ams fabric of the granites several rock magnetism experiments performed in one specimen from each sampled site show that for all sites the magnetic susceptibility is dominantly carried by ferromagnetic minerals while mainly magnetite carries the magnetic fabrics lineations and foliations in the granite facies were successful determined by applying magnetic methods magnetic lineations are gently plunging and roughly parallel to the boundaries of the pluton facies except at the few sites in the central facies which have a radial orientation pattern in contrast the magnetic foliations tend to follow the contacts between the different granite facies they are gently outerward dipping inside the pluton and become either steeply southwesterly dipping or vertical towards its margin the lack of solid state and subsolidus deformations at outcrop scale and in thin sections precludes deformation after full crystallization of the pluton this evidence allows us to interpret the observed magnetic fabrics as primary in origin magmatic acquired when the rocks were solidified as a result of processes reflecting magma flow the foliation pattern displays a dome shaped form for the main lsic pluton however the alkaline granites which outcrop in the southern part of the studied area have an inward dipping foliation and the steeply plunging magnetic lineation suggests that this area could be part of a feeder zone the magma ascent probably occurred due to ring diking

a model for vertical to horizontal response spectral ratios for europe and the middle east in the framework of probabilistic seismic hazard analysis the preferred approach for obtaining the response spectrum of the vertical component of motion is to scale the horizontal spectrum by vertical to horizontal v h spectral ratios in order to apply these ratios to scenario or conditional mean spectra the v h ratios need to be defined as a function of variables such as magnitude distance and site classification a new model for the prediction of v h ratios for peak ground acceleration and spectral accelerations from 0 02 to 3 0 s is developed from the database of strong motion accelerograms from europe and the middle east a simple functional form expres sing the v h ratios as a function of magnitude style of faulting distance and site class is found to be appropriate and the associated aleatory variability is found to be at least as low as that obtained in other studies using more complex models the predicted ratios from the new european model are found to be in broad agreement with recent models derived from predominantly western north america data

characterization of the magnetic fabric of rocks abstract an inextensive system of magnetic susceptibility anisotropy factors is suggested which is sufficient in the majority of practical applications for characterizing the magnetic fabric of rocks the system involves three newly devised factors the corrected anisotropy degree the shape factor and the difference shape factor the first of these characterizes the quantity of anisotropy somewhat better than the commonly used anisotropy degree the shape factor characterizes the quality of anisotropy i e the shape of the susceptibility ellipsoid in a convenient way its definition is based on a certain analogy between the anisotropy ellipsoid and the strain ellipsoid the difference shape factor can replace the shape factor when only the differences between the principal susceptibilities are given while the mean susceptibility is unknown

empirical prediction equations for peak ground velocity derived from strong motion records from europe and the middle east peak ground velocity pgv has many applications in earthquake engineering but there are relatively few prediction equations for this parameter in comparison with the large numbers of equations for estimating peak ground accel eration and response spectral ordinates this lack of empirical equations for pgv has led to widespread use of the practice of scaling peak velocity from the 5 damped response spectral ordinate at 1 sec which is a poor substitute for direct prediction of the parameter responding to the need to provide equations for the prediction of pgv this article derives new equations using the strong motion database for the seismically active areas of europe and the middle east following a new processing of all of the records a total of 532 strong motion accelerograms recorded at distances of up to 100 km from 131 earthquakes with moment magnitudes ranging from m 5 to 7 6 are used to derive equations for both the larger and the geometric mean of the horizontal components the predictions are found to be broadly consistent with those from previous european equations and also with preliminary results from the next generation of attenuation nga project suggesting that systematic differences in ground motions from active crustal regions if any are sufficiently small not to prevent the combined use of strong motion data from southern europe western north america and other tectonically active areas of shallow crustal seismicity

empirical stochastic ground motion prediction for eastern north america an alternative approach based on a hybrid empirical model is utilized to predict the ground motion relationship for eastern north america ena in this approach a stochastic model is first used to derive modification factors from the ground motions in western north america wna to the ground motions in ena the ground motion parameters are then estimated to develop an empirical attenuation relationship for ena using empirical ground motion relationships from wna w e develop an empirical stochastic source model for both regions to obtain ground mo tions at different magnitude distance range of interest at short distances r 30 km and large magnitudes mw 6 4 an equivalent point source model is carried out to consider the effect of finite fault modeling on the ground motion parameters source focal depth and brune stress drop are assumed to be magnitude dependent we choose three well defined empirical attenuation relationships for wna to com pare the empirical ground motion processes between the two regions a composite functional attenuation form is defined and in turn a nonlinear regression analysis is performed by using a genetic algorithm ga for a wide range of magnitudes and distances to develop an empirical attenuation relationship from the stochastic ground motion estimates in ena the empirical stochastic attenuation relationship for hor izontal peak ground acceleration and spectral acceleration are applicable to earth quakes of mw 5 0 8 2 at distances of up to 1000 km the resulting attenuation model developed in this study is compared with those used in the 2002 national seismic hazard maps derived in the 2003 electric power research institute studies and re corded in ena the comparison of the results to the other attenuation functions and the available ena data show a reasonable agreement for the ena ground motions

the relation between magnetite and silicate fabric in granitoids of the adamello batholith abstract the link between the macroscopic silicate fabric and the magnetite controlled ams anisotropy of magnetic susceptibility fabric in ferromagnetic rocks was investigated through a comprehensive comparison between different fabric measurement techniques sample lithologies include tonalites and granodiorites from the lago della vacca complex adamello batholith italy the datasets used to assess the link between subfabrics and the coherence between methods include 1 macroscopic silicate fabric measured directly in the field 2 macroscopic silicate fabric derived from image analysis ia of outcrop pictures and sample pictures 3 shape preferred orientations spo of mafic silicates 4 spo of magnetite and 5 calculated distribution of magnetite grains from computer assisted high resolution x ray tomography x ray ct images 6 fabrics derived from the ams macroscopic mineral fabrics measured in the field agree with the ia results and with the spo of mafic silicates obtained from the x ray ct imaging the x ray ct results show that the spo of the magnetite grains are consistent with the ams data whereas the spatial distribution of the magnetite grains is less compatible with the ams fabric this implies that the ams signal is mainly controlled by the shape of the magnetic carrier mineral rather than by the spatial arrangement of the magnetite grains an exception is the presence of magnetite clusters furthermore the spo of mafic silicates and the spo of the magnetite grains are consistent with the ams data another finding of this study is that the magnetic susceptibility correlates linearly with the amount of magnetite in the samples the coherent results obtained from a variety of methods reinforce the application of both ams measurements and ia as robust tools to analyse fabrics in granitic intrusions

interpreting magmatic fabric patterns in plutons abstract most plutons have widespread magmatic fabrics the interpretation of which remains controversial we propose a method to constrain likely causes of fabric patterns the application of which indicates the following 1 preserved fabric patterns often form after chamber construction and only rarely provide information about ascent or emplacement 2 fabrics are poor recorders of total strain and are easily reset preserving only the last increment of strain during crystallization 3 in magmatic systems mechanically decoupled from host rocks patterns may result from strain during internally driven flow filter pressing or porous flow in relatively static chambers or by final increments of strain during emplacement 4 with greater emplacement depths fabric patterns increasingly reflect strain caused by regional deformation and 5 given that magmatic fabrics are easily reset and reflect only the last increment of strain of comparatively weak materials they may provide a relatively direct record of paleostress in orogenic belts

the attenuation of fourier amplitudes for rock sites in eastern north america we develop an empirical model of the decay of fourier amplitudes for earthquakes of m 3 6 recorded on rock sites in eastern north america and discuss its implications for source parameters attenuation at distances from 10 to 500 km may be adequately described using a bilinear model with a geometric spreading of 1 r 1 3 to a transition distance of 50 km with a geometric spreading of 1 r 0 5 at greater distances for low frequencies and distances less than 50 km the effective geometric spreading given by the model is perturbed using a frequency and hypocentral depth dependent factor defined in such a way as to increase amplitudes at lower frequencies near the epicenter but leave the 1 km source amplitudes unchanged the associated anelastic attenuation is determined for each event with an average value being given by a regional quality factor of q 525f 0 45 this model provides a match on aver age between the known seismic moment of events and the inferred low frequency spectral amplitudes at r 1 km obtained by correcting for the attenuation model the inferred brune stress parameters from the high frequency source terms are about 600 bars 60 mpa on average for events of m 4 5

partially nonergodic empirical ground motion models for predicting horizontal and vertical pgv pga and 5 damped linear acceleration response spectra using data from the iranian plateau we present new ground motion prediction equations gmpes to estimate horizontal and vertical strong ground motion intensity measures gmims generated by shallow active crustal earthquakes occurring within the iranian plateau to this end a dataset containing 688 records from 152 earthquakes with moment magnitudes ranging from 4 7 to 7 4 and joyner boore distances up to 250 km has been used the effects of the local site condition are taken into account using the time averaged shear wave velocities in the upper 30 m v s 30 we decided not to include the style of faulting term in the final functional form because the total standard deviation is reduced 10 by removing this term from the functional form we used a nonlinear mixed effects regression to determine the coefficients of the functional form and to separate out the between event and between station standard deviations from the total standard deviation significant standard deviation of site to site variability demonstrates that the ergodic assumption is not able to account for the spatial variability of ground motions we introduced random effects coefficients to capture regional variations between different tectonic regions of the iranian plateau such as alborz and zagros in the regression analysis to investigate the effects of regionalization on gmpes the results showed that although the effects of regional variations for considered regions are negligible at close distances they are significant at longer distances the complexity and performance of the final functional form is justified by comparing akaike and bayesian information criteria values over many trial functional forms moreover the distribution of between event site to site and event station corrected residuals demonstrates that no trends are evident implying satisfactory performance of the proposed gmpes therefore the derived gmpes can be employed to predict gmims and to do seismic hazard assessments within the iranian plateau electronic supplement 1 lists of the events and stations considered in the final dataset and derived coefficients of the functional form 1 http www bssaonline org lookup suppl doi 10 1785 0120160205 dc1

analysis of the 2005 2016 earthquake sequence in northern iran using the visibility graph method we present an analysis of the seismicity of northern iran in the period between 2005 and 2016 using a recently introduced method based on concepts of graph theory the method relies on the inter event visibility defined in terms of a connectivity degree parameter k which is correlated with the earthquake magnitude m previous studies show that the slope m of the line fitting the k m plot by the least squares method also observes a relationship with the b value from the gutenberg richter law thus rendering the graph analysis useful to examine the seismicity of a region these correlations seem to hold for the analysis of relatively small sequences of earthquakes offering the possibility of studying seismicity parameters in time we apply this approach to the case of the seismicity of northern iran using an earthquake catalog for the tectonic seismic regions of azerbaijan alborz and kopeh dagh we use results drawn for this region with the visibility graph approach in combination with results from other similar studies to further improve the universal relationship between m and b and show that the visibility graph approach can be considered as a valid alternative for analyzing regional seismicity properties and earthquake sequences

anisotropy of magnetic remanence a brief review of mineralogical sources physical origins and geological applications and comparison with susceptibility anisotropy the magnetic fabric of rocks and sediments is most commonly characterized in terms of the anisotropy of low field magnetic susceptibility ams however alternative methods based on remanent magnetization measured in the absence of a magnetic field rather than induced magnetization measured in the applied field have distinct advantages for certain geological applications this is particularly true for 1 adjunct studies in paleomagnetism in order to assess the fidelity with which a natural remanence records the paleofield orientation 2 studies of weakly magnetic or weakly deformed rocks for which susceptibility anisotropy is very difficult to measure precisely and 3 quantitative applications such as strain estimation the fundamental differences between susceptibility and remanence and their respective anisotropies are due to several factors 1 susceptibility arises from all of the minerals present in a sample whereas remanence is carried exclusively by a relatively small number of ferromagnetic minerals 2 ferromagnetic minerals are generally more anisotropic than para and diamagnetic minerals 3 for ferromagnetic minerals remanence is inevitably more anisotropic than susceptibility and 4 a number of common minerals including single domain magnetites possess an inverse anisotropy of susceptibility i e they tend to have minimum susceptibility parallel to the long axis of an individual particle remanence is immune to this phenomenon as a consequence of all these factors remanence anisotropy may generally provide a better quantitative estimate of the actual distribution of particle orientations in a rock sample

empirical attenuation of ground motion spectral amplitudes in southeastern canada and the northeastern united states a database of 1700 digital seismograms from 186 earthquakes of mag nitude mn 2 5 5 6 that occurred in southeastern canada and the northeastern united states from 1990 to 2003 was compiled maximum likelihood regression analysis of the database was performed to determine a model for the attenuation of fourier spectral amplitudes for the shear window for the vertical and horizontal component of motion for frequencies from 0 2 to 20 hz fourier amplitudes follow a hinged trilinear attenuation model fourier spectral amplitudes decay as r 1 3 where r is hypocentral distance within 70 km of the source there is a transition zone from 70 to 140 km as the direct waves are joined by strong postcritical reflections where the attenuation is described as r 0 2 spectral amplitudes actually increase with distance in this range for low frequencies beyond 140 km the attenuation is well described by r 0 5 corresponding to geometric spreading in two dimensions the associated model for the regional quality factor for frequencies greater than 1 hz can be ex pressed as q 893f 032 q can be better modeled over a wider frequency range 0 2 20 hz by a polynomial expression log q 3 052 0 393 log f 0 945 log f 2 0 327 log f 3 the polynomial expression accommodates the observation that q values are at a minimum about 1000 near 1 hz and rise at both lower and higher frequencies correction factors for the spectral amplitude model that describe the effects of focal depth on the amplitudes and their attenuation are developed using the subset of events with known focal depth the attenuation model is similar to that determined from an earlier study with more limited data atkinson and mereu 1992 but the enlarged database indicates more rapid near source amplitude decay and higher q the attenuation model is used to play back attenuation effects to determine the apparent source spectrum for each earthquake in the database and hence determine moment magnitude m and brune stress drop the events have moment magnitude in the range from 2 5 to 5 stress drop increases with moment magnitude for events of m 4 3 then appears to attain a relatively constant level in the range from 100 to 200 bars for the larger events as previously noted in atkinson 1993b the results of this study provide a useful framework for improving regional ground motion relations in eastern north america they further our understanding of attenuation in the region through analysis of an enlarged ground motion database in particular the inclusion of the three component broadband data gathered over the last decade allows extension of attenuation models to both horizontal and vertical components over a broad frequency range 0 2 20 hz

attenuation of lg waves in the new madrid seismic zone of the central united states using the coda normalization method abstract unique properties of coda waves are employed to evaluate the frequency dependent quality factor of lg waves using the coda normalization method in the new madrid seismic zone of the central united states instrument and site responses are eliminated and source functions are isolated to construct the inversion problem for this purpose we used 121 seismograms from 37 events with moment magnitudes m ranging from 2 5 to 5 2 and hypocentral distances from 120 to 440 km recorded by 11 broadband stations a singular value decomposition svd algorithm is used to extract q values from the data while the geometric spreading exponent is assumed to be a constant inversion results are then fitted with a power law equation from 3 to 12 hz to derive the frequency dependent quality factor function the final results of the analysis are q v lg f 410 38 f 0 49 0 05 for the vertical component and q h lg f 390 26 f 0 56 0 04 for the horizontal component where the term after sign represents one standard error for stations within the mississippi embayment with an average sediment depth of 1 km around the memphis metropolitan area estimation of quality factor using the coda normalization method is not well constrained at low frequencies f

patterns of historical earthquake rupture in the iranian plateau the iranian plateau accommodates the 35 mrn yr convergence rate be tween the eurasian and arabian plates by strike slip and reverse faults with relatively low slip rates in a zone 1000 km across although these faults have only locally been the subject of paleoseismological studies a rich historical and archeological record spans several thousand years long enough to establish recurrence intervals of 1000 to 5000 yr on individual fault segments several clusters of earthquakes provide evidence of interaction among reverse and strike slip faults probably due to adjacent faults being loaded by individual earthquakes the dasht e bayaz sequence of 1936 to 1997 includes earthquakes on left lateral right lateral and reverse faults the neyshabur sequence of four earthquakes between 1209 and 1405 respected the seg ment boundary between the neyshabur and binalud reverse fault systems the two pairs of earthquakes may have ruptured different faults in each segment similar to the 1971 and 1994 san fernando california earthquakes the 1978 tabas reverse fault earthquake was preceded by the 1968 ferdows earthquake part of the dasht e bayaz sequence the north tabriz fault system ruptured from southeast to north west in three earthquakes from 1721 to 1786 a previous cluster may have struck this region in 855 to 958 the mosha fault north of tehran ruptured in three earthquakes in 958 1665 and 1830 five large earthquakes struck the tehran region from 743 to 1177 but only two that large have struck the area since 1177 other earthquakes occurred in pairs in the talesh mountains near the caspian sea 1863 1896 the iran turkey border 1840 1843 and the nayband gowk fault system both 1981 other historical events did not occur as parts of sequences the historic seismic moment release in iran accounts for only a small part of the plate convergence rate which may be due to aseismic slip or to the iranian historical record long as it is being too short to sample long term deformation across the plateau no historic earthquakes of m 8 have struck iran however several long straight strike slip faults doruneh west neh east neh and nayband have not sustained large historical earthquakes raising the possibility that these long faults could produce earthquakes of m 8 thereby removing at least part of the apparent slip deficit an increased understanding of iran s seismic hazard could be obtained by an extensive paleoseismology program and space geodetic arrays supplementing the abundant historical and archaeological record

thermal history of alberta deep basin comparative study of fluid inclusion and vitrinite reflectance data the thermal history of the alberta deep basin the gas saturated westernmost part of the western canadian sedimentary basin has been studied by analyzing aqueous and hydrocarbon fluid inclusions in diagenetic cements and comparing the results with coal maturity data results indicate that most of the diagenetic quartz druse precipitated from low salinity fluids 2 3 wt at a temperature of 170 195 c calcite cement precipitated after quartz druse during uplift and cooling at temperatures of 108 169 c inclusions rich in larger hydrocarbon molecules occur in cements that precipitated at 150 c whereas methane rich inclusions occur in cements that precipitated at 165 c or at lower temperatures after significant uplift and cooling of the b sin maximum burial temperatures tmb calculated from vitrinite reflectance data using the lopatin waples tti ro calibration are significantly lower 150 c than the temperature at which quartz druse precipitated in the same area 190 c an equation directly relating tmb and ro proposed by barker and pawlewicz in 1986 yields maximum burial temperatures 200 210 c only slightly higher than the fluid temperatures the results from this study suggest that hot fluids migrated updip along permeable conglomerates and bedding plane fractures to produce unexpectedly high geothermal gradients 38 c km in the western part of the study area the apparent restriction of hot fluids to the western part of the study area sugge ts that convective heat transfer by fluids may have operated on a scale of only tens of kilometers in lower cretaceous rocks of the alberta deep basin

emplacement and deformation of the fomopea pluton implication for the pan african history of western cameroon abstract the fomopea pluton 622 613 ma is located in the western part of the pan african belt in cameroon it comprises of 3 units biotite hornblende granitoids bhg biotite monzogranites bmg and edenite syenogranites esg the bhg unit displays magnetic fabrics characterized by foliations gently dipping towards the ese and ene trending lineations d1 event microstructures are magmatic to submagmatic in discrete n s deformation bands d2 lineations are rotated towards the north and microstructures indicate solid state deformation at mid to low t conditions with kinematic indicators pointing to a sinistral motion the second unit bmg displays lineation trajectories suggesting emplacement during the d2 event the esg unit displays fabrics consistent with a later emplacement with no superposed deformation the last event d3 corresponds to a dextral shear zone that runs along the southeastern border of the fomopea pluton it was responsible for protomylonitic deformation of the granitic rocks in greenschist facies conditions whereas the core of the shear zone registered higher temperatures and strain this shear zone induced a rejuvenation of the rb sr isotopic system in the pluton at ca 572 ma it belongs to the central cameroon shear zone system regarded as the prolongation of the dextral patos shear zone system in brazil

magnetic anisotropy of some phyllosilicates magnetic susceptibility anisotropy of susceptibility and hysteresis of single microcrystals of chlorite biotite phlogopite muscovite zinnwaldite and fuchsite were measured in low and high magnetic fields with an alternating gradient force magnetometer micromag their properties are sufficient to account for the low field susceptibility ams of most micaceous rocks nearly all samples show some ferromagnetic contribution at low fields due to inclusions of pseudosingle domain and multidomain magnetite the paramagnetic contribution isolated at high fields usually exceeds the ferromagnetic contribution the paramagnetic susceptibility is intrinsic to the silicate lattice and agrees with values predicted from chemical composition within the limits of error the minimum susceptibility is nearly parallel to c another axis is parallel to b and the third susceptibility usually the maximum is close to a the paramagnetic susceptibility has a disk shaped magnitude ellipsoid with strong anisotropy p 2 the ferromagnetic contributions at low fields have more variably shaped ellipsoids with greater eccentricity p 5 the silicate lattice does not constrain their orientation our technique cannot determine the principal axes of the ferromagnetic component however its principal values usually correspond with the paramagnetic principal susceptibilities in order of magnitude thus the combined paramagnetic ferromagnetic anisotropy recognised in routine studies of ams should faithfully represent the petrofabric of most micaceous rocks nevertheless nearly 10 of our samples have incompatible anisotropy ellipsoids for the silicate host and magnetite inclusions these yield a net inverse ams that does not correctly represent the orientation of the silicate lattice therefore some caution is necessary in petrofabric ams studies of micaceous rocks

anisotropies of partial anhysteretic remanence and susceptibility in compacted black shales grainsize and composition dependent magnetic fabric we have quantified the magnetic fabric of the highly compacted heebner shale pennsylvanian of kansas in terms of the anisotropies of partial anhysteretic remanent magnetization parm and low field susceptibility hysteresis loops exhibit almost purely paramagnetic behavior and the ratio of high field linear susceptibility to low field susceptibility is very close to one the susceptibility anisotropy therefore reflects the fabric of the paramagnetic matrix while the remanent anisotropies are due to the preferred orientations of ferrimagnetic grains both the paramagnetic and ferrimagnetic fabrics are dominated by a horizontal foliation with a weak northeasterly lineation but the parm anisotropies are generally much larger than the susceptibility anisotropy the degree of foliation measured with parm s decreases markedly with increasing coercivities indicating stronger foliation in the coarser grainsize fraction in contrast the parm mean lineations are grainsize independent suggesting a post compactional origin related to tectonic compression the susceptibility lineation appears to have a slightly different azimuth and may therefore be due to paleocurrents

model validations and comparisons of the next generation attenuation of ground motions nga west project abstract the earthquake ground motion prediction equations developed for the next generation attenuation of ground motions nga west project in 2008 have established a new baseline for the estimation of ground motion parameters such as peak ground acceleration peak ground velocity and spectral acceleration for shallow crustal earthquakes in active tectonic regions we perform statistical goodness of fit analyses to quantitatively compare the predictive capabilities of the nga models and their predecessors using several testing subsets of the master database used in model development in addition we perform a blind comparison test using 1060 ground motion records from seven recent earthquakes recorded in california the 2003 m 6 5 san simeon event 2004 m 6 0 parkfield event 2005 m 5 2 anza event 2007 m 5 4 alum rock event 2008 m 5 4 chino hills event 2010 m 7 2 baja event and 2010 m 5 7 ocotillo event we assess how modeling decisions regarding the regression dataset functional forms input parameters and model complexity influence the models predictive capabilities by comparing the performance of each model we discuss various ground motion modeling strategies and offer recommendations for model development we find that increased model complexity does not necessarily lead to increased prediction accuracy that the inclusion of aftershocks in regression datasets may result in decreased predictive capabilities for mainshocks and that the use of measured site characteristics leads to greatly improved ground motion predictions a model validation framework is introduced to assess the prediction accuracy of ground motion prediction equations and to aid in their future development

distribution anisotropy the cause of ams in igneous rocks understanding of ams in pristine basic igneous rocks in terms of flow orientation of ellipsoidal magnetite grains is thwarted by the fact that these grains 1 typically are irregularly equant or skeletal rather than distinctly ellipsoidal and 2 usually crystallize interstitially and late after magma flow has ceased however the distribution of such grains will be relatively anisotropic if they grew in residual liquid volumes within a preferredly oriented by flow silicate template this constraint may impose a slight preferred shape orientation to the irregular magnetite grains during their growth but in addition we suggest it is the anisotropic magnetic interaction between the grains which is the basic cause of ams experiments involving the casting of magnetite epoxy mixtures in various foliated or lineated glass templates have yielded samples with the expected ams symmetry i e k3 perpendicular to glass plates or k1 parallel to glass rods slicing of near isotropic synthetic blank and natural rock cores and interleaving with glass slides showed a progressive increase in anisotropy of the blank from 0 4 to 2 and the natural rock from 0 9 to 2 9 in both the k3 axis migrates to be perpendicular to the glass slides

self indentation of a heterogeneous continental lithosphere the neoproterozoic ribeira aracuai belt stretches along the southeastern edge of the sao francisco craton of southeastern brazil and extends south of the cratonic domain for 1000 km the termination of the craton is spatially correlated with a significant modification of the deformation pattern in the belt 1 the structural trend bends from due north to northeast 2 the dominant tectonic flow shifts from orogen transverse to orogen normal and 3 the metamorphic conditions of deformation decrease southwestward from high to medium grade finite element modeling suggests that the presence of a craton within a continent favors strain localization initiation of continental scale shear zones and differential vertical deformations the southward termination of the sao francisco craton may have triggered the development of the complex deformation pattern that characterizes the ribeira aracuai belt

effects of magnetic interactions in anisotropy of magnetic susceptibility models experiments and implications for igneous rock fabrics quantification besides granites of the ilmenite series in which the anisotropy of magnetic susceptibility ams is mainly controlled by paramagnetic minerals the ams of igneous rocks is commonly interpreted as the result of the shape preferred orientation of unequant ferromagnetic grains in a few instances the anisotropy due to the distribution of ferromagnetic grains irrespective of their shape has also been proposed as an important ams source former analytical models that consider infinite geometry of identical and uniformly magnetized and coaxial particles confirm that shape fabric may be overcome by dipolar contributions if neighboring grains are close enough to each other to magnetically interact on these bases we present and experimentally validate a two grain macroscopic numerical model in which each grain carries its own magnetic anisotropy volume orientation and location in space compared with analytical predictions and available experiments our results allow to list and quantify the factors that affect the effects of magnetic interactions in particular we discuss the effects of i the infinite geometry used in the analytical models ii the intrinsic shape anisotropy of the grains iii the relative orientation in space of the grains and iv the spatial distribution of grains with a particular focus on the inter grain distance distribution using documented case studies these findings are summarized and discussed in the framework of the generalized total ams tensor recently introduced by canon tapia canon tapia e 2001 factors affecting the relative importance of shape and distribution anisotropy in rocks theory and experiments tectonophysics 340 117 131 the most important result of our work is that analytical models far overestimate the role of magnetic interaction in rock fabric quantification considering natural rocks as an assemblage of interacting and non interacting grains and that the effects of interaction are reduced by i the finite geometry of the interacting clusters ii the relative orientation between interacting grains iii their heterogeneity in orientation shape and bulk susceptibility and iv their inter distance distribution we reconcile analytical models and experiments with real case studies that minimize the role of magnetic interaction onto the measured ams limitations of our results are discussed and guidelines are provided for the use of ams in geological interpretation of igneous rock fabrics where magnetic interactions are likely to occur

magnetic fabrics and their relationship with the emplacement of the piracaia pluton se brazil magnetic fabric and rock magnetism studies were performed on the four units of the 578 3 ma old piracaia pluton nw of sao paulo state southern brazil this intrusion is roughly elliptical 32 km2 composed of i coarse grained monzodiorite mzd c ii fine grained monzodiorite mzd f which is predominant in the pluton iii monzonite heterogeneous mzn het and iv quartz syenite qz sy magnetic fabrics were determined by applying both anisotropy of low field magnetic susceptibility ams and anisotropy of anhysteretic remanent magnetization aarm the two fabrics are coaxial the parallelism between ams and aarm tensors excludes the presence of a single domain sd effect on the ams fabric of the units several rock magnetism experiments performed in one specimen from each sampled units show that for all of them the magnetic susceptibility and magnetic fabrics are carried by magnetite grains which was also observed in the thin sections foliations and lineations in the units were successfully determined by applying magnetic methods most of the magnetic foliations are steeply dipping or vertical in all units and are roughly parallel to the foliation measured in the field and in the country rocks in contrast the magnetic lineations present mostly low plunges for the whole pluton however for eight sites they are steep up to vertical thin section analyses show that rocks from the piracaia pluton were affected by the regional strain during and after emplacement since magmatic foliation evolves to solid state fabric in the north of the pluton indicating that magnetic fabrics in this area of the pluton are related to this strain otherwise the lack of solid state deformation at outcrop scale and in thin sections precludes deformation in the sw of the pluton this evidence allows us to interpret the observed magnetic fabrics as primary in origin magmatic acquired when the rocks were solidified as a result of magma flow in which steeply plunging magnetic lineation suggests that a feeder zone could underlie this area

magnetic fabrics and microstructures of the jurassic shah kuh granite pluton lut block eastern iran and geodynamic inference abstract the jurassic shah kuh granite pluton was emplaced in the northeastern part of the lut block eastern iran while this block was a part of the active margin under which the tethys ocean that separated arabia from central iran was subducting since this time the lut block has rotated and migrated northward up to its present position this structural study of the shah kuh aims at strengthening the evidence of its original geodynamical location thanks to a systematic collection of oriented samples in the field well defined fabric and microstructural patterns were deduced from magnetic fabric measurements and optical microscopy observations the overall magnetic fabric of the pluton yields vertical north south striking foliations and shallow lineations plunging to the north the corresponding microstructures attest to their formation in the magmatic stage i e during emplacement subsequent deformation characterized by sub mylonitic microstructures has modified the original fabric into a northwest and locally a west northwest trend inside a two kilometre wide corridor this corridor reflects the trace of a sinistral shear zone that offsets the previous north south magmatic pattern of the pluton the latter magmatic pattern is proposed to result from the shear component of strain that was parallel to the ancient active margin during pluton emplacement as a result of strain partitioning a situation frequently documented at convergent margins sinistral shear along an e w directed south facing active margin assuming a northeastward slip vector for the tethys ocean during the jurassic and accepting a 150 counterclockwise rotation of the lut block after emplacement of the shah kuh pluton best explains both the magmatic and the solid state lineation patterns

ground motion attenuation relationship for east central iran predictive attenuation relationships have been developed for peak ground acceleration and spectral coordinates based on observed and simulated records for east central iran first the predictive relationships are derived based on observed records the observed data set which was considered includes a total of 258 records from 109 earthquakes with a magnitude range of 5 0 7 4 on rock site then a suite of ground motions has been simulated for a range of magnitude and distances based on the stochastic finite fault ground motion model the theoretical empirical attenuation relationship which has been developed for the horizontal component of peak ground acceleration and spectral acceleration is applicable to earthquakes of m w 5 0 7 4 at a distance up to 100 km online material earthquake catalog

site effect evaluation using spectral ratios with only one station the spectral ratio technique is a common useful way to estimate empirical transfer function to evaluate site effects in regions of moderate to high seismicity the purpose of this paper is to show that it is possible to estimate empirical transfer function using spectral ratios between horizontal and vertical components of motion without a reference station the technique originally proposed by nakamura to analyze rayleigh waves in the microtremor records is presented briefly and it is discussed why it may be applicable to study the intense s wave part in earthquake records results are presented for three different cities in mexico oaxaca oax acapulco gro and mexico city these cities are very different by their geological and tectonic contexts and also by the very different epicentral distances to the main seismogenic zones affecting each city each time we compare the results of nakamura s technique with standard spectral ratios in all three cases the results are very encouraging we conclude that if site effects are caused by simple geology a first estimate of dominant period and local amplification level can be obtained using records of only one station

tectonic rotations and internal structure of eocene plutons in chuquicamata northern chile abstract a paleomagnetic and ams study on eocene plutonic complexes in the calama area northern chile reveals high temperature high coercivity magnetizations of dominantly thermoremanent origin and magnetic fabrics controlled by magnetite the paleomagnetic results indicate that 43 ma plutons underwent clockwise tectonic rotation whereas adjacent 39 ma plutons did not undergo discernible rotation this points to a middle eocene age for the younger tectonic rotations associated with the central andean rotation pattern in the chuquicamata calama area the petrofabric in these rocks formed under conditions ranging from purely magmatic i e before full crystallization to low temperature solid state deformation ams and paleomagnetism suggest that the plutonic bodies were formed by progressive amalgamation of subvertical magma sheets spanning multiple magnetic polarity chrons the parallelism between magmatic and tectonic foliations suggests that regional tectonic stress controlled ascent emplacement and rock deformation during cooling in this context we suggest that magma ascent and emplacement in the upper crust likely exploited mesozoic structures which were locally reactivated in the eocene

a theoretical and experimental comparison of the anisotropies of magnetic susceptibility and remanence in rocks and minerals summary susceptibility thermo remanent magnetization trm and isothermal remanent magnetization irm anisotropy ellipsoids have been determined for several rock samples the results indicate that the ellipsoid of initial susceptibility is less anisotropic than the trm and low field irm ellipsoids which are found experimentally to be of identical shape this suggests that palaeomagnetic data for anisotropic rocks may be corrected by using the anisotropy ellipsoid determined from magnetically non destructive low field irm measurements such irm measurements can also be used to obtain anisotropy axes of samples which are inherently anisotropic but which have a susceptibility which is too weak to be accurately measured the results for a series of artificial anisotropic samples containing magnetite particles of different sizes in the range 0 2 90 m were very similar to those for the rocks in contrast a comparison of the susceptibility and irm ellipsoids for anisotropic samples containing particles from a magnetic tape gave very different results in accordance with theory such results imply that susceptibility and irm ellipsoids could be used to determine whether anisotropic rocks contain uniaxial single domain particles magnetization confined to the easy axis or whether the particles are essentially multidomain

magnetic fabric of the řicany granite bohemian massif a record of helical magma flow abstract a highly unusual fabric pattern and inferred flow mechanism was discovered in the shallow level icany granite pluton bohemian massif using an integrated structural and anisotropy of magnetic susceptibility ams study the pluton consists of an outer strongly porphyritic and an inner weakly porphyritic biotite granite separated by a wide gradational contact both varieties share a steep margin parallel magmatic foliation defined by k feldspar phenocrysts and biotite and magnetic ams foliation carried by biotite the steep foliation bears a shallowly plunging magnetic lineation arranged parallel to the circumference of the pluton margin and a steep magnetic lineation in the weakly porphyritic pluton center we propose a new mechanism of magma flow in which the bulk ascent along a steep sided cylindrical conduit was partitioned into a high viscosity phenocryst rich outer margin flowing helically and a low viscosity phenocryst poor center flowing vertically this interpretation is supported quantitatively by a simple model of magma flow within a cylindrical pipe in which the linear decrease in phenocryst content from the pluton margin inwards causes a power law decrease in the effective viscosity of the magma according to the poiseuille equation such a power law viscosity distribution across the conduit produces a central zone of high magma ascent velocity the magnetic ams fabric pattern in the icany pluton may thus preserve a record of helical magma ascent driven by viscosity partitioning in a steep sided conduit which presumably linked an underlying magma chamber with a volcanic feeder at the surface except for one deep seated granite migmatite complex no such helical fabric pattern has been documented in a granite pluton as of yet we propose that the viscosity partitioned helical flow may be a more common magma ascent mechanism in shallow level volcano plutonic systems than previously envisaged

a review of criteria for the identification of magmatic and tectonic foliations in granitoids abstract foliations in granitoids can form by magmatic flow submagmatic flow high temperature solid state deformation and moderate to low temperature solid state deformation a review of previous work suggests that no single criterion can consistently distinguish foliations in granitoids formed by flow during ascent diapiric emplacement and expansion emplacement during regional deformation or regional deformation post dating emplacement however a magmatic origin is favoured for foliations defined by the alignment of igneous commonly euhedral minerals particularly where the foliation is parallel to internal or external pluton contacts foliations formed during expansion or ballooning of diapirs may be strictly magmatic in origin although some studies suggest that solid state deformation also may occur if so we would hope to find evidence of deformation of crystal melt systems and that the solid state deformation occurred at high temperatures the inference of syntectonic foliations is most convincing where magmatic and high temperature solid state foliations are subparallel these foliations are continuous with regionally developed foliations in the wall rocks synkinematic porphyroblasts are present in the wallrocks and igneous minerals have the same age as metamorphic minerals associated with the regional cleavage a strictly tectonic origin for foliations in granitoids is favoured when the foliation is defined by metamorphic minerals no alignment of igneous minerals occurs the foliation is locally at high angles to pluton wallrock contacts and the foliation is continuous with a regionally developed cleavage

estimation of the coda wave attenuation and geometrical spreading in the new madrid seismic zone using the single backscattering method coda quality factor functions through coda window lengths of 20 30 40 50 and 60 s have been estimated for the new madrid seismic zone nmsz furthermore geometrical spreading functions for distances less than 60 km have been determined in this region at different center frequencies exploiting the coda normalization method a total of 284 triaxial seismograms with good signal to noise ratios snr 5 from broadband stations located in the nmsz were used the database consisted of records from 57 local earthquakes with moment magnitudes of 2 6 4 1 and hypocentral distances less than 200 km q factor values were evaluated at five frequency bands with central frequencies of 1 5 3 6 12 and 24 hz vertical components were utilized to estimate vertical coda q factor values horizontal coda q factor values were determined using the average amount of the q factor values estimated from two orthogonal horizontal components the coda q factor increases with increasing of the coda window length implying that with increasing the depth the coda q factor increases the intermediate values of the q factor and intermediate values of the frequency dependency indicate that the earth s crust and upper mantle beneath the entire nmsz is tectonically a moderate region with a moderate to relatively high degree of heterogeneities the geometrical spreading factors of s wave amplitudes are frequency dependent and determined to be 0 761 0 991 1 271 1 182 and 1 066 for center frequencies of 1 5 3 6 12 and 24 hz respectively at hypocentral distances of 10 60 km the geometrical spreading factors for lower frequencies are not recommended to be used due to the greater impact of the radiation pattern and directivity effect on low frequencies as well as the greater sensitivity of band pass filtered seismograms of small earthquakes to the noise in low frequencies

emplacement modes of the ladinian plutonic rocks of the dolomites insights from anisotropy of magnetic susceptibility abstract in the dolomites eastern southern alps italy a diffuse middle triassic igneous activity is now present mostly as lava flow and pyroclastic successions with rare shallow depth intrusive bodies cropping out at predazzo monzoni and cima pape areas in this work the emplacement modes of the predazzo and monzoni bodies were investigated by means of petrographic and anisotropy of magnetic susceptibility ams data coupled with a field geological study the presence of intrusive rocks in between these two bodies and the continuity of the metamorphic aureola from west of the predazzo to east of the monzoni body suggest that they are parts of a 20 km wide sw ne oriented continuous pluton sub parallel to ladinian strike slip faults ams and petrographic data from the predazzo body are consistent with a multistage ring dyke emplacement mode with areas of upward flow of the magma located in the nw and ese part of the intrusion whereas in the southern sector of the pluton our data suggest prevalently horizontal flows in general the predazzo sheets indicate either upward magma flow or along strike lateral magma transport and the round shape suggests no influence of ladinian tectonic structures on the contrary the ene wsw elongated shape of the monzoni body was controlled by the occurrence of strike slip faults associated with ladinian tectonics the feeder being likely located at the ne edge of the body however the absence of deformation at the field and micro scale is consistent with a post ladinian tectonics timing of emplacement as for the predazzo pluton

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

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

a study of horizontal to vertical component spectral ratio in the new madrid seismic zone the horizontal to vertical component h v spectral ratio of the small and moderate earthquake ground motions for the shear wave window was used as an estimation of the site response in the new madrid seismic zone nmsz the database used in this study consisted of 500 broadband seismograms from 63 events of magnitude mw 2 5 to 5 2 recorded on 11 stations operated by the university of memphis center for earthquake research and information ceri at the university of memphis all the broadband stations were located within the mississippi embayment soil deposits overlying the rock basement of the embayment strongly affected the amplitudes of the ground motions the horizontal to vertical component ratios were evaluated for the frequency range of 0 2 to 20 hz the observed average h v ratios suggested site amplification between 2 and 4 in the low frequency range f 5 hz for stations located on the lower shear wave velocity deposits lowlands the higher shear wave velocity deposits uplands indicated low frequency amplification be tween 1 5 and 3 hz the observed average h v ratios were also compared with the soil amplifications in the upper mississippi embayment developed by romero and rix 2005 from the 1d equivalent linear method for generic regional profiles the h v ratios were also compared with the theoretical quarter wavelength approx imation these comparisons suggested that the h v ratios could be a first estimate of the site amplifications finally the variability of the h v ratios with distance was examined and no discernible trends were found therefore the path effect model developed by zandieh and pezeshk 2010 for thevertical ground motions in nmsz using the database of this study was also applicable for the horizontal ground motions

deciphering relative timing of fabric development in granitoids with similar absolute ages based on ams study dharwar craton south india abstract anisotropy of magnetic susceptibility ams data are presented from the koppal granitoid dharwar craton south india that has u pb zircon age of 2528 9 ma the magnetic fabric is oriented in nne ssw direction this is parallel to the planar structures that developed during regional d 3 deformation but oblique to the nnw sse oriented magnetic foliation as well as field foliation d 1 d 2 deformation recorded in the country rock peninsular gneiss variation in the intensity of fabric within the granitoid is mapped it is inferred that the emplacement of koppal granitoid took place by ballooning and fabric development within the pluton was syntectonic with regional d 3 these results are compared with the time relationship between emplacement fabric development and regional deformation reported from the mulgund granite 2555 6 ma u pb zircon which is also located in the dharwar craton and is equivalent to the koppal granitoid in age this granite is known to have emplaced syntectonically with regional d 1 d 2 deformation and is thus not related to the same deformation event as the koppal granitoid despite their similar absolute ages it is argued that in the study area d 3 is 2537 ma while d 1 d 2 is 2549 ma in age thus this study highlights the use of ams in a deciphering the relative timing of regional deformation and emplacement of granitoids of equivalent age and b constraining the timing of regional superposed deformation events