regional retrograde metamorphism of a high grade terrain the willyama complex broken hill australia abstract retrograde metamorphism has been a major influence in the development of the presently observed lithologies of the willyama complex broken hill two broad types of retrogression are distinguished pseudomorphous and kinematic retrogression the former type of retrogression involves replacement of prograde phases without complete loss of the high grade fabric hence the prograde assemblage can frequently be inferred kinematic retrogression involves the development of a new schistose fabric and like pseudomorphous retrogression is commonly related to f3 deformation retrogression was initiated during the waning stage of prograde metamorphism and was accompanied by an influx of aqueous fluid at similar pressure but lower temperature conditions than prograde metamorphism the source of the water is believed to be the crystallization of cooling partial melts the regional nature of this willyama style of retrogression is attributed to the metasediment rich nature of the sequence the high geothermal gradient and the considerable amount of in situ partial melting

small scale deformations associated with the 1992 landers california earthquake mapped by synthetic aperture radar interferometry phase gradients the landers earthquake mw 7 3 occurred on june 28 1992 and ruptured nearly 100 km of previously mapped and unmapped faults in the mojave desert we use synthetic aperture radar interferometry insar to examine the cumulative surface deformation between april 24 and august 7 1992 in a 100 100 km region surrounding the northern portion of the earthquake rupture also we introduce a technique for manipulating sar interferograms to extract short wavelength displacement information this technique involves computation and subsequent combination of interferometric phase gradient maps the insar results show significant deformation signatures associated with faults fractures dry lake beds and mountainous regions within 75 100 km of the main rupture using the phase gradient method we are able to extract small scale deformation patterns near the main rupture many of the preexisting mapped faults within 50 km of the main rupture experienced triggered slip these include the old woman lenwood johnson valley west calico and calico faults the insar results also indicate right lateral offsets along secondary fractures trending n ne within the left lateral zone of shear between the main rupture and the johnson valley fault additionally there are interesting interferogram fringe signatures surrounding troy dry lake and coyote dry lake that are related to deformation of dry lake beds

sulfur isotopic variations among minerals and aqueous species in the salton sea geothermal system a shrimp ion microprobe and conventional study of active ore genesis in a sediment hosted environment

uranium and boron distributions related to metamorphic microstructure evidence for metamorphic fluid activity the distribution of uranium and boron in polymetamorphosed granulite facies schists and gneisses has been studied using particle track methods the concentration and distribution of these elements when examined in relation to mineralogy and microstructure provide an insight into 1 the behaviour of u and b in metamorphism 2 the activity of a fluid phase in the metamorphic processes and 3 the nature of chemical processes during schistosity development a low concentration of primary u occurs in micro inclusions of apatite and zircon many are metamict in the granulite facies m1 assemblage this assemblage which lacks b except for zoned sillimanite has undergone a localized retrograde metamorphism rm1 characterised by hydrous alteration products containing abundant u and b the rm1 metamorphism is attributed to fluids generated during granulite facies dehydration reactions a schistosity s2 defined by m2 fibrolite aggregates overprints the m1 events it is associated with 1 intragranular u concentrated in m2 apatite and titanium bearing minerals and 2 abundant intergranular u within the fibrolite aggregates high b contents also occur with the fibrolite the s2 schistosity appears to develop in a metamorphic environment containing a fluid enriched in u and b

the boron isotope geochemistry of the neogene borate deposits of western turkey abstract we have analyzed the boron isotope composition of 80 borate minerals major minerals borax colemanite and ulexite minor minerals veatchite a tunellite kernite terrugite probertite meyer hofferite inderite inyoite hydroboracite howlite and pandermite from the main deposits kirka bigadic and emet and two smaller deposits kestelek and sultancayir in the western turkish borate deposits forty three samples were also analysed for their sr isotope composition the data span a wide range in 11b values from 1 6 o to 25 3 o the 11b values of the main borate minerals are largely controlled by their mineralogy and the ph of the brines from which they precipitated an inverse correlation between the average 11b and 87 sr 86 sr ratios of colemanite in the different deposits suggests there is some variation in the sources of boron and sr to the deposits emet has the highest contribution from aluminosilicates and kirka the highest contribution from eocene carbonates with bigadic occupying an intermediate position the 11b values of the minor borate minerals distinguish between those which are primary precipitates from the original brines or formed from primary borates without boron loss from the system and those which formed from alteration of preexisting borate minerals with substantial loss of boron from the system

structure and mechanical properties of faults in the north anatolian fault system from insar observations of coseismic deformation due to the 1999 izmit turkey earthquake 1 we study the structure and mechanical properties of faults in the north anatolian fault system by observing near fault deformation induced by the 1999 mw 7 4 izmit earthquake turkey we use interferometric synthetic aperture radar insar and global positioning system observations to analyze the coseismic surface deformation in the near field of the izmit rupture the overall observed coseismic deformation is consistent with deformation predicted by a dislocation model assuming a uniform elastic crust previous insar studies revealed small scale changes in the radar range across the nearby faults of the north anatolian fault system in particular the mudurnu valley and iznik faults e g wright et al 2001 we demonstrate that these anomalous range changes are consistent with an elastic response of compliant fault zones to the stress perturbation induced by the izmit earthquake we examine the spatial variations and mechanical properties of fault zones around the mudurnu valley and iznik faults using three dimensional finite element models in these models we include compliant fault zones having various geometries and elastic properties and apply stress changes deduced from a kinematic slip model of the izmit earthquake the best fitting models suggest that the inferred fault zones have a characteristic width of a few kilometers depth in excess of 10 km and reductions in the effective shear modulus of about a factor of 3 compared to the surrounding rocks the characteristic width of the best fitting fault zone models is consistent with field observations along the north anatolian fault system ambraseys 1970 our results are also in agreement with insar observations of small scale deformation on faults in the eastern california shear zone in response to the 1992 landers and 1999 hector mine earthquakes fialko et al 2002 fialko 2004 the inferred compliant fault zones likely represent intense damage and may be quite commonly associated with large crustal faults

a brine interface in the salton sea geothermal system california fluid geochemical and isotopic characteristics data from 71 geothermal production intervals in 48 wells from the salton sea geothermal system ssgs indicate that fluids in that system cluster into two distinct populations in terms of their salinity and their stable isotopic compositions the distinctive hot hypersaline brine typically 20 wt total dissolved solids for which the ssgs is known is overlain by a cooler 260 c fluid with distinctly lower salinity typically 10 wt total dissolved solids hypersaline brines have high and rather consistent 18o shifts produced by water rock interaction and have a very narrow range in d values low tds fluids on the other hand show a wide range in both d and 18o production of both types of fluid from closely spaced geothermal wells in many regions of the ssgs indicates that a relatively sharp salinity interface exists over much of the field the fluid interface typically cross cuts sedimentary bedding but is consistently found where reservoir temperatures are approximately 260 c at these temperatures hypersaline brines have densities of approximately 1 0 gm cm3 while the low tds fluids have densities as low as 0 85 gm cm3 this stable density stratified interface acts as a barrier to convective heat and mass transfer in the ssgs isolating the hypersaline reservoir from overlying dilute fluids a lithologic cap implied by previous ssgs models is unnecessary in such a stratified system since heat and mass transfer across the interface must occur by slow conductive diffusional and interface mixing processes regardless of local permeability

finite fault inversion of dinsar coseismic displacement of the 2009 l aquila earthquake central italy 1 we define the geometric and kinematic characteristics of the fault activated during the mw 6 3 6 april 2009 l aquila earthquake from the modeling of envisat and cosmo skymed the first ever x band interferogram inverted for a coseismic dislocation study dinsar interferograms our best fit solution for the main shock is represented by a normal fault 16 km long and 12 km wide with a small right lateral component dipping 47 sw with a maximum slip of 90 cm although the seismic dislocation probably ended at 1 km depth the updip projection of the fault plane corresponds to the northern segment of the mapped paganica s demetrio fault where alignment of surface breaks was observed in the field the absence of this fault in existing seismic source catalogues suggests that an improved approach involving detailed surface and subsurface geological and geophysical investigations is needed for a better assessment of the seismic hazard at the local scale

petrogenesis and magmatic hydrothermal evolution time limitation of kelumute no 112 pegmatite in altay northwestern china evidence from zircon upb and hf isotopes abstract granitic pegmatites and associated rare metal deposits unique features in the altay orogen are located in a key tectonic position of the southern central asian orogenic belt caob and document the tectonic evolution of the paleo asian ocean the kelumute no 112 pegmatite which intruded into the jideke two mica granites hosts abundant rare metal e g li be nb ta ore deposits and ranks only second to the koktokay no 3 pegmatite in both size and reserves to explore the evolution time limitation of magmatic magmatic hydrothermal and hydrothermal stages in the pegmatite magma system the tectonic setting and the genetic relationship between pegmatites and granites this study presents zircon u pb and hf isotopic compositions of the kelumute no 112 pegmatite and the wall rocks two mica granite and biotite granite as determined by la icpms and la mc icpms the weighted mean 206 pb 238 u ages of the internal textural zones of the pegmatite including zones i ii iii v and vi are 238 3 2 0 ma 233 5 3 7 ma 188 3 1 7 ma 218 8 1 9 ma and 210 7 1 6 ma respectively wall rocks of two mica granite and biotite granite are dated at 445 6 4 3 ma and 455 6 5 4 ma respectively zircons from the kelumute no 112 pegmatite have lower positive e hf t values 0 03 to 2 35 with t dm model ages of 1112 1225 ma wall rocks show similar zircon e hf t values 1 41 to 4 13 and t dm model ages 1172 to 1515 ma however three xenocrystic zircons from the granites are characterized by larger negative ehf t values 5 85 to 9 83 and older t dm model ages 1839 to 2090 ma thus the following conclusions can be drawn 1 the kelumute no 112 pegmatite and its wall rocks jideke two mica granite and biotite granite have no genetic relationship as indicated by the large gaps between their formation ages however they did originate from a common source composed of ancient crust and mantle derived materials under two different tectonic settings 2 the magmatic magmatic hydrothermal transition and hydrothermal stages of the no 112 pegmatite magma lasted for 5 ma 23 ma and 22 ma respectively and 3 the no 112 pegmatite magma was most likely formed in a post collision tectonic setting indicating that block amalgamation and collisional orogeny of the caob continued into the triassic

fault scarps and deformation rates in lazio abruzzo central italy comparison between geological fault slip rate and gps data abstract we compare new and literature data concerning the integrated deformation rate since 18 ka for the central apennines with deformation rate data derived from a 6 year gps campaign we constructed topographic profiles across the majority of the active faults in the area we derived deformation rate data from displaced post glacial sediments and slopes associated with the last major glacial retreat that occurred in the region about 18 kyr ago paleoseismic investigations in this region clearly show that offset of these features is the cumulative effect of repeated surface faulting earthquakes with magnitudes in the range 5 5 ms 7 0 a cumulative throw rate diagram incorporating both our values and the values extracted from the literature i e previously published trenching studies scarp profiles and offset terraces is presented providing a regional picture of the spatial deformation rate distribution in the central apennines during the latest pleistocene and holocene by converting cumulative throw rates into heave rates we calculate maximum extension rates of ca 2 mm year at the location of the same transect where 6 2 mm year has been measured with gps over 6 years this discrepancy between geodetic and geological fault slip rate data implies that we have to be cautious whenever we use gps data for seismic hazard assessment purposes or when attempting to reconstruct the tectonic processes in an area because geodetic data may be unrepresentative of the longer term deformation rates on the other hand this discrepancy may provide insights into the mechanics of the seismic cycle we discuss various scenarios that may explain the mis match between long term and short term measurements

tourmalines from appalachian caledonian massive sulfide deposits textural chemical and isotopic relationships tourmaline is a common gangue mineral in several strata bound massive sulfide deposits of the appalachian caledonian orogen most of the tourmaline rich deposits occur in dominantly metasedimentary terranes such as bleikvassli norway black hawk maine ore knob north carolina and elizabeth vermont minor amounts of tourmaline are also known in association with volcanic hosted deposits in the appalachians and in the trondheim district of norway the tourmaline forms isolated euhedral crystals or crystal aggregates in massive sulfide and adjacent wall rocks in a few areas it is found in conformable tourmaline rich layers tourmalinites associated minerals may include quartz plagioclase phlogopite and dolomite with pyrrhotite chalcopyrite galena and sphalerite many of the tourmaline crystals are optically zoned in which brown zones concentrically alternate with pale yellow or green zones a few specimens of tourmaline intergrown with massive sulfide e g ore knob display fine delicate growth lamellae similar to those commonly observed in hydrothermal vein sphalerites skarn garnets and sphalerites from the massive sulfide deposits of the kuroko district japan detailed geochemical studies indicate that the tourmalines have characteristic major and trace element compositions electron microprobe analyses show that with rare exception the tourmalines are mg rich dravites avg feo feo mgo 0 21 abrupt transitions between color zones within some tourmaline are accompanied by relative variations in feo feo mgo of as much as 30 percent yellow brown zones are more mg rich than blue or green zones in contrast the fine growth lamellae are not characterized by such variations in chemistry spectrographic analyses of pure mineral separates indicate that the tourmalines also contain high average contents of cr 78 ppm cu 77 ppm pb 114 ppm sr 98 ppm and v 195 ppm while uniformly low in li 7 ppm and mn 382 ppm in all analyzed samples fluorine is much more abundant than chlorine the average f cl ratio is 33 tourmalines from tourmalinites and massive sulfide deposits are typically characterized by heavier delta 18 o values 9 5 15 5ppm and less variable heavier delta d values generally 45 to 60ppm than tourmalines from unmetamorphosed igneous pegmatites the latter typically have delta 18 o 9 5 per mil and delta d or 60 per mil oxygen isotope fractionations between quartz and tourmaline delta 1 27 4 01 do not correlate directly with inferred grade of subsequent metamorphism although in areas of high metamorphic grade the delta values approach those of igneous quartz tourmaline pairs the delta 18 o values of quartz and tourmaline are believed to reflect variation in the oxygen isotope compositions of the host lithologies the similar narrow range in hydrogen isotope composition for tourmaline in all studied deposits is compatible with a modified seawater origin for the tourmaline and sulfide forming fluids the distinctive textural and chemical characteristics of the tourmalines reported here have both exploration and genetic significance though it may have undergone recrystallization and some accompanying chemical and isotopic exchange during regional metamorphism tourmaline in the massive sulfide deposits is an early formed perhaps diagenetic mineral in which fine lameliar zoning may be a preserved premetamorphic feature in any case the tourmalines from the massive sulfide deposits are mg rich dravites with trace element and stable isotope compositions substantially different from those of the fe rich schorls typical of most granitic rocks these geochemical and isotopic signatures are attributed to the original environment of formation of the associated sulfide deposits and suggest that mg rich tourmaline may be a valuable prospecting guide in the search for massive sulfide deposits

rare earth element geochemistry of clastic and chemical metasedimentary rocks associated with hydrothermal sulphide mineralisation in the olary block south australia abstract analysis of a variety of rock types from the south australian portion of the lower to middle proterozoic willyama inliers by icp ms demonstrate that primary rare earth element ree distributions remained essentially unchanged despite multiphase deformation and amphibolite grade metamorphism variable trends of preferential ree mobilisation are observed only where large amounts of fluid caused the rock to undergo strong retrogression and or hydrothermal alteration except for these conditions ree can be considered immobile and their distribution is generally independent of mineralogy thus providing a powerful tool for the characterisation of provenance of protoliths in a high grade metamorphic terrain ree signatures and other geochemical constraints of some volcanogenic sediments for example point to an andesitic parentage suggesting bimodal and gradually changing volcanism occurring in a developing intracontinental rift zone ree distributions in metasediments associated with sulphide mineralisation reflect both physico chemical characteristics of the ore bearing fluids and rock compositions comparison of their ree profiles allows discrimination between a strata bound redox controlled deposits b exhalative mineralisation and c epigenetic vein type mineralisation ree distributions in the analysed rocks are in agreement with other lines of textural and geochemical evidence for that limited syn tectonic remobilisation low fluid rock ratios unchanged primary ree signatures but widespread late stage mobilisation of sulphides high fluid rock ratios selective mobilisation of ree occurred in the olary block ree signatures of exhalative precipitates associated with sulphide mineralisation do not show a systematic stratigraphic variation but are indicative of fluctuating f o 2 conditions over short distances and display only moderately positive eu anomalies this contrasts with findings for the adjacent broken hill block and highlights the dissimilarities of ore formation processes that were active in the olary and the broken hill block as well as the depositional differences between the two blocks

the primary role of the paganica san demetrio fault system in the seismic landscape of the middle aterno valley basin central apennines abstract the paganica normal fault that caused the april 9 2009 l aquila earthquake central apennines is part of the paganica san demetrio fault system psdfs all available data useful to constrain the quaternary activity of the psdfs were reviewed with the aim to point out its role in the landscape evolution of the l aquila region and particularly of the middle aterno valley basin uplifted remnants of a low relief landscape summit paleosurface sp constrain to about 800 m the total offset of the psdfs since the late lower pleistocene also a sedimentary cycle ended at the beginning of middle pleistocene is now displaced about 550 m along the psdfs whereas alluvial deposits containing tephra layers 560 360 ka have been displaced more than 150 m by the paganica fault segment the long term slip rate values based on this evidence ranging between 0 4 and 0 9 mm y together with the short term slip rate values based on displacements along late pleistocene geomorphic features and deposits have shown that the psdfs i has played a primary role in the landscape evolution of the area despite its minor geomorphic appearance ii is linked at depth with other important listric faults located in the psdfs footwall assergi and campo imperatore faults that in this paper are interpreted as secondary faults this result has relevant seismotectonic implications for the middle aterno valley basin the psdfs is the main seismic source of the basin and controls also the seismic potential of other linked structures including the assergi and campo imperatore faults

complex deformation at shallow depth during the 30 october 2016 m w 6 5 norcia earthquake interference between tectonic and gravity processes the relation between slip at the near surface and at depth during earthquakes is still not fully resolved at the moment this deficiency leads to large uncertainties in the evaluation of the magnitude of past earthquakes based on surface observations which is the only accessible evidence for such events a better knowledge of the way slip distributes over distinct rupture strands within the first few kilometers from the surface would contribute greatly to reduce these uncertainties the 30 october 2016 mw6 5 norcia earthquake has been captured by a variety of geodetic techniques which provide access to the slip distribution both at depth and at the ground surface with an unprecedented level of detail for a normal faulting earthquake we first present coseismic surface offset measurements from correlation of optical satellite images of submetric resolution which are compared to field observations made shortly after the earthquake based on a joint inversion of optical data together with insar and gps data we then propose a rupture model that explains the observations both at far field and near field scales finally we explore different rupture geometries at shallow depth in an attempt to better explain the near field deformation i e within the first hundreds of meters around the fault observed at the surface despite the fact that the solution is not unique several lines of evidence suggest that gravity processes could be locally involved which interfere with the dominant tectonic processes

probing the mechanical properties of seismically active crust with space geodesy study of the coseismic deformation due to the 1992 mw7 3 landers southern california earthquake 1 the coseismic deformation due to the 1992 m w 7 3 landers earthquake southern california is investigated using synthetic aperture radar sar and global positioning system gps measurements the ers 1 satellite data from the ascending and descending orbits are used to generate contiguous maps of three orthogonal components east north up of the coseismic surface displacement field the coseismic displacement field exhibits symmetries with respect to the rupture plane that are suggestive of a linear relationship between stress and strain in the crust interferometric synthetic aperture radar insar data show small scale deformation on nearby faults of the eastern california shear zone some of these faults in particular the calico rodman and pinto mountain faults were also subsequently strained by the 1999 m w 7 1 hector mine earthquake i test the hypothesis that the anomalous fault strain represents essentially an elastic response of kilometer scale compliant fault zones to stressing by nearby earthquakes fialko et al 2002 the coseismic stress perturbations due to the landers earthquake are computed using a slip model derived from inversions of the insar and gps data calculations are performed for both homogeneous and transversely isotropic half space models the compliant zone model that best explains the deformation on the calico and pinto mountain faults due to the hector mine earthquake successfully predicts the coseismic displacements on these faults induced by the landers earthquake deformation on the calico and pinto mountain faults implies about a factor of 2 reduction in the effective shear modulus within the similar to 2 km wide fault zones the depth extent of the low rigidity zones is poorly constrained but is likely in excess of a few kilometers the same type of structure is able to explain high gradients in the radar line of sight displacements observed on other faults adjacent to the landers rupture in particular the lenwood fault north of the soggy lake has likely experienced a few centimeters of left lateral motion across 1 km wide compliant fault zone having the rigidity reduction of more than a factor of 2 the inferred compliant fault zones are interpreted to be a result of extensive damage due to past earthquakes

the willyama supergroup in the broken hill and euriowie blocks new south wales abstract the willyama supergroup consists of highly deformed metasedimentary schists and gneisses with abundant quartzofeldspathic gneisses lesser basic gneisses and minor lode rocks prograde metamorphism ranged from andalusite through sillimanite to granulite grade radiometric dating in the broken hill block indicates separation of the source of the quartzo feldspathic gneisses from the mantle at 2300 2100 ma a rb sr model source age of 1820 60 ma has been interpreted as the maximum age of deposition deformation d 1 and or d 2 was coincident with high grade metamorphism at 1660 10 ma minor mundi mundi type granitoids and some pegmatites were intruded at 1490 20 ma minor pyroxenites at 561 7 ma dolerite dykes soon after and zoned pegmatites at 500 ma in association with the delamerian orogeny which reactivated retrograde schist zones at 520 40 ma subsequent history mostly comprises faulting weathering uplift and erosion the willyama supergroup has an estimated total thickness of 7 9 km with neither top nor basement exposed no unconformities have been recognized in the sequence the supergroup was deposited in a deepening environment passing upward from sandy facies to more shaly and fine sandy facies and from interpreted bimodal acid basic volcanics to non volcanic facies the metasediments have been interpreted as shelf sediments overlain by deeper water turbidites and minor contourites recently they have been reinterpreted as shallow marine with the quartzo feldspathic gneisses interpreted as fluvio deltaic arkoses in this paper the sequence to the top of thackaringa group is interpreted as mainly fluvio deltaic and lacustrine the broken hill group and sundown group are interpreted as shallow marine the paragon group may have comprised shelf muds overlain by delta front and lacustrine sediments in turn overlain by deeper water fine grained turbidites the broken hill orebody near the top of broken hill group consists of a series of stacked lenses much recent work has concluded that the deposit is volcanic exhalative in origin probably formed from seawater convected through the sequence and driven by heat from high level magma chambers however some features of the deposit are more appropriate to a sedimentary exhalative origin and models have been proposed involving seismic pumping of connate water with ore deposition on or below the seafloor devolatilization of the mantle has been proposed as a source of ore constituents deposition may have occurred in a narrow ne sw trending seafloor depression the willyama supergroup was probably deposited in a rift zone with thin crust the basic gneisses are interpreted as fe rich tholeiites similar to basalts from some oceanic spreading ridges the intense folding post folding leucogranitic intrusions and extensive granulite amphibolite facies metamorphism could have resulted from a collision following subduction however there is no direct evidence of oceanic crust or subduction and the low pressure metamorphic path does not suit a collision model the rocks were probably deposited in a continental rift with some similarities to those interpreted for proterozoic fold belts in northern australia

insar data as a field guide for mapping minor earthquake surface ruptures ground displacements along the paganica fault during the 6 april 2009 l aquila earthquake 1 on 6 april 2009 a moderate earthquake mw 6 3 ml 5 8 struck the abruzzo region in central italy causing more than 300 fatalities and heavy damage to l aquila and surrounding villages coseismic surface effects have been thoroughly documented by timely field surveys as well as by remote sensing analyses of satellite images the outstanding quality of geological seismological geodetic and interferometric synthetic aperture radar insar information arguably represents the best ever data set made available immediately after a moderate seismic event based on this data set we aim at testing the capability of coupled geological and insar data to map surface faulting patterns associated with moderate earthquakes coseismic ground ruptures have been mapped at a scale of 1 500 in the whole epicentral area traces of surface ruptures have been inferred from linear phase discontinuities identified in the interferogram a very good agreement between the two methods resulted in the characterization of the main surface rupture along the paganica fault the same approach applied to ground ruptures hypothesized along other capable fault segments provided more questionable results thus the combined field and insar approach appeared useful for detecting continuous surface ruptures exceeding 1 km in length and showing displacements greater than a few centimeters these are the typical faulting parameters for moderate earthquakes 6 0 mw 6 5 in central apennines for continuous ground cracks shorter than a few hundred meters and or that show displacements smaller than 1 2 cm the described approach may be less helpful most probably due to the limited resolution of the data

fast characterization of sources of recent italian earthquakes from macroseismic intensities abstract we analysed the intensity data collected immediately after three strong earthquakes mw 6 that occurred in italy in the last decade to infer location orientation and size of the relevant seismogenic faults using the boxer method we show that starting from a few hours after the earthquake such macroseismic method could have provided a characterization of the seismogenic source comparable to instrumental methods some of which would have required much more time to provide stable results particularly for the 6 april 2009 earthquake the analysis of macroseismic survey data could have been able to accurately constrain starting already from the early afternoon of the day of the main shock location orientation and size of the area of maximum coseismic displacement related to the activation of the paganica s demetrio fault system for the 20 may 2012 emilia and the 24 august 2016 amatrice earthquakes preliminary macroseismic surveys were carried out within a few days from the main shocks but their data were made available publicly a month later for the 20 may 2012 emilia earthquake the orientation of the fault could have been correctly determined even if the size would have been underestimated for the 24 august 2016 amatrice earthquake both the orientation and the size could have been correctly assessed we also compared such macroseismic determinations with those obtained for some historical earthquakes in the same areas the analysis of the cumulate intensities observed after the shocks of 24 august 26 and 30 october 2016 indicates an overall mw 6 8 comparable to that mw 6 9 of the largest earthquake occurred in the same section of the apennines 14 january 1703 even if the inferred orientations of the 2016 and 1703 boxes are very similar the epicentres differ of about 20 km indicating a probable distinct fault system for the two earthquakes

origin and significance of tourmalinites and tourmaline bearing rocks of menderes massif western anatolia turkey abstract in the western central portion of anatolia lies the menderes massif a large metamorphic crystalline complex made of neoproterozoic to precambrian basement rocks overlain by palaeozoic to early tertiary metasedimentary rocks and with a multistage metamorphic evolution developed from the late neo proterozoic to eocene we have undertaken a study of the petrology geochemistry and boron isotope composition of these tourmaline occurrences aiming to constrain the processes responsible for the enrichment of boron and other fluid mobile elements in the menderes massif the dispersed tourmaline has chemical and boron isotope compositions typical of a continental crust setting but while some of the tourmalinites display similar signatures others have heavier boron isotope compositions up to 7 5 we suggest that the tourmalinites with continental characteristics formed part of the original pan african basement rocks whereas those with heavier 11b signatures formed by later metamorphism during the alpine orogeny possibly through interaction with subduction like fluids this proposed process may also have been coincident with metasomatism of the lithospheric mantle beneath the massif which is known to have experienced multistage metasomatism and enrichment history up to neogene time

boron isotope geochemistry of the oceanic crust from dsdp odp hole 504b boron contents and boron isotopic compositions were determined for the uppermost 1 3 km section of typical 6 2 ma oceanic crust from dsdp odp hole 504b costa rica rift galapagos spreading center both the boron content and the 11b value in the oceanic crust are controlled by two types of alteration 1 1 low temperature alteration 0 to 60 c zones i and ii and 2 2 high temperature hydrothermal alteration 200 to 400 c zones iii and iv basalts subjected to the low temperature alteration are characterized by their relatively high boron contents 0 69 to 19 3 ppm and high 11b values 2 2 to 10 6 indicating uptake of boron into secondary phases in equilibrium with seawater or evolved seawater hydrothermally altered basalts contain less abundant boron 0 17 to 0 52 ppm and relatively constant 11b values 0 1 to 1 0 although basalts from the upper part of these hydrothermal zones 1300 mbsf original boron content and 11b value of the hole 504b morb were 0 35 ppm and 0 2 respectively the present data provide fundamental information in understanding of the distribution of boron and boron isotopes in the oceanic crust

the 2009 l aquila central italy mw6 3 earthquake main shock and aftershocks 1 a m w 6 3 earthquake struck on april 6 2009 the abruzzi region central italy producing vast damage in the l aquila town and surroundings in this paper we present the location and geometry of the fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks the distribution of aftershocks 712 selected events with m l 2 3 and 20 with m l 4 0 defines a complex 40 km long nw trending extensional structure the main shock fault segment extends for 15 18 km and dips at 45 to the sw between 10 and 2 km depth the extent of aftershocks coincides with the surface trace of the paganica fault a poorly known normal fault that after the event has been quoted to accommodate the extension of the area we observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes

chemical and boron isotope compositions of non marine brines from the qaidam basin qinghai china the general chemistry and boron isotope composition were investigated in fresh waters and hypersaline brines from the qaidam basin northern qinghai xizang tibet plateau china this basin is a large tectonically active system isolated from the ocean and composed of thick clastic and evaporite sediments the modern playas are subject to intense evaporation and are characterized by hypersaline brines as well as potash and borate evaporites the chemical composition of the dissolved solutes in the modern brines and waters reveals three main sources 1 inflow of hot springs enriched in sodium sulphate and boron evaporation of these waters leads to a high na cl ratio 1 a na cl so4 brine and an evaporite mineral assemblage of halite mirabilite borate lakes daqaidam and xiaoqaidam 2 inflow surface river waters which are modified by preferential dissolution of halite and potassium and magnesium salts characterized by a na mg cl solute type with low na cl 1 brcl licl and bcl ratios and 3 ca chloridic subsurface brines which are controlled by both salt dissolution and dolomitization processes evaporation and salt crystallization of mixtures of the latter two types leads to a marine like brine e g na mg cl type nacl ratio 1 and mineral assemblages similar to that predicted for progressive evaporation of seawater e g qarhan playa halite sylvite carnallite bischofite the 11 b values of the input waters to the qaidam basin range of 0 7 to 10 9 vs nbs 951 and brines from salt lakes 0 5 to 15 0 are similar to those of associated granitic rocks 11b 2 3 to 3 7 n 3 and hence indicate the non marine origin of these fluids the highest 11b values are associated with fluids with low bli ratios indicating selective removal of elemental boron and 10b by adsorption onto clay minerals the magnitude of 11b enrichment due to adsorption is 15 20 and thus non marine brines are well distinguished from marine derived brines 11b of 39 to 59 preserving the large isotopic difference 40 of their source waters it is proposed to use this distinctive isotopic signature for tracing the origin of ancient evaporite environments

boron isotope evidence for the involvement of non marine evaporites in the origin of the broken hill ore deposits identifying the palaeogeographic setting and mode of origin of stratabound ore deposits can be difficult in high grade metamorphic terranes where the effects of metamorphism may obscure the nature of the protoliths here we report boron isotope data for tourmalines from the early proterozoic broken hill block in australia which hosts giant lead zinc silver sulphide deposits with one exception the 11b 10b ratios are lower than those for all other tourmalines from massive sulphide deposits and tour malinites elsewhere in the world we propose that these low ratios reflect leaching of boron from non marine evaporitic borates by convecting hydrothermal fluids associated with early proterozoic continental rifting a possible modern analogue is the salton sea geothermal field in california

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

lithostratigraphy of the state 2 14 borehole salton sea scientific drilling project sedimentary rocks from the california state 2 14 research borehole of the salton sea scientific drilling project located in the imperial valley of southern california were deposited in the continental basin of the salton trough lacustrine shale and siltstone are the dominant lithologies sandstones were deposited in lake margin meander channel fill and lacustrine delta environments framework modal clast compositions of the sandstones indicate a dominant colorado river provenance rare pebbly mudstones were deposited as storm induced debris flows primary depositional structures in the sediments are commonly disrupted by seismic disturbances nonmarine gastropods and ostrocods are relatively uncommon and occurrences of stratabound sulfides suggest periods of brackish water conditions bedded anhydrite and centimeter scale mudcracks record intervals of dessication the state 2 14 sedimentary rocks are interpreted as the basinward facies of the borrego and brawley formations which range from pliocene to pleistocene in age

sedimentary model for the giant broken hill pb zn deposit australia during the past 15 years there has been increasing acceptance of a volcanic exhalative origin for the giant 300 mt broken hill pb zn orebody supposedly silicic pyroclastic rock types have been identified in the host rock succession and because of an association with basic volcanics amphibolites comparison is made with phanerozoic continental rifts the orebody has also been described as distal and deep water we report that the so called silicic volcanic rocks are all normal clastic sediments the metasedimentary succession more than 5 km thick is interpreted as a series of major continental fluvio deltaic progradational wedges interfingering with marine transgressive cycles deposited in a gradually deepening basin pb zn mineralization is hosted by shallow marine sands that later became reservoirs for the metal bearing brines basin formation stratigraphic architecture and pb zn mineralization can all be interpreted in terms of concepts understood from studies of the development of younger sedimentary basins the inference is that pb zn mineralization was generated by compactive expulsion of metal bearing brines during accumulation of the sedimentary pile

coseismic ground deformation of the 6 april 2009 l aquila earthquake central italy mw6 3 1 we provide field data of coseismic ground deformation related to the 6 april mw 6 3 l aquila normal faulting earthquake three narrow fracture zones were mapped paganica colle enzano p e mt castellano mt stabiata c s and san gregorio sg these zones define 13 km of surface ruptures that strike at 130 140 we mapped four main types of ground deformation free faces on bedrock fault scarps faulting along synthetic splays and fissures with or without slip that are probably due to the near surface lithology of the fault walls and the amount of slip that approached the surface coseismically the p e and c s zones are characterized by downthrow to the sw up to 10 cm and opening up to 12 cm while the sg zone is characterized only by opening afterslip throw rates of 0 5 0 6 mm day were measured along the paganica fault where paleoseismic evidence reveals recurring paleo earthquakes and post 24 8 kyr slip rate 0 24 mm yr

active ore formation at a brine interface in metamorphosed deltaic lacustrine sediments the salton sea geothermal system california the salton sea geothermal system is an area of active hydrothermal metamorphism of pliocene to pleistocene deltaic lacustrine and evaporitic sediments deposited in a modern continental rift zone temperatures up to 365 degrees c hypersaline metalliferous brines with up to 26 wt percent total dissolved solids and active base metal ore formation accompany low pressure greenschist and amphibolite facies metamorphism at depths less than 3 2 km drill cores recovered by the salton sea scientific drilling project shed new light on the nature and origin of ore formation in the eastern portion of the salton sea geothermal system base metal ore mineralization occurs in vertical fractures that comprise the major form of fluid permeability at 1 to 3 km in the modern geothermal system type 1 veins are dominated by carbonate contain pyrrhotite and other sulfides are completely sealed and occur in wall rock showing minimal alteration fluid inclusion data indicate that they were deposited under a thermal gradient much higher than that now found in the eastern part of the system type 2 veins are dominated by silicates and hematite are permeable and occur in wall rocks showing pervasive chloritization and epidotization fluid inclusion data indicate that they are forming now from the geothermal brines under the modern thermal gradient fluid inclusions record an apparent steep progressive salinity increase in the vein systems in the upper 2 km of the system however fluid production data from salton sea geothermal wells indicate that reduced metalliferous hypersaline brine averaging 23 wt percent total dissolved solids is overlain by more oxidized metal poor fluid averaging 5 wt percent total dissolved solids a sharp interface exists between the fluids at 1 to 2 km paralleling the 250 degrees c isothermal surface a model is developed for type 2 vein ore formation involving mixing at the interface between the two fluids magmatic intrusion induces fracturing heating and the expulsion of reduced connate fluids to cause early type 1 vein mineralization following the rising thermal front deep hypersaline brine rises diapirically and mixes with overlying fluids in vertical fractures transecting the ascending interface forming type 2 veins the hypersaline brine rises to a level of density temperature stabilization causing pervasive greenschist metamorphism of the host sediments the diapir then begins to cool and descend shallow oxidized brine is drawn in as the hypersaline brine descends promoting late stage hematite in type 2 veins the eastern salton sea geothermal system presently appears to be in this latter mode of cooling and retrograde brine descent ore formation in the system is caused by the coincidence of transaxial entry of a major river into an active rift zone deposition of metal bearing deltaic sediments to form a closed basin sedimentary environment episodic lacustrine evaporite formation and injection of heat and elements by rift related magmatic intrusions at depth the presence of an upwelling brine diapir in the system may be analogous to conditions immediately prior to the exhalation of metalliferous fluids that formed stratiform fe zn pb cu sulfide and oxide deposits in paleorift zone environments

active crustal extension in the central apennines italy inferred from gps measurements in the interval 1994 1999 we present the first gps estimate of crustal extension in the central apennines italy through the analysis of the deformation of a sub network of the national gps geodetic network igm95 in the interval 1994 1999 the selected sub network spans the entire active deformation belt perpendicularly to its axis and allows the evaluation of 1 the total extension rate absorbed in this sector of the apennines and 2 the seismogenic potential of the normal faults active in the late pleistocene holocene interval within the network results of this reoccupation are consistent with an extensional strain rate of 0 18 10 6 yr 1 concentrated in an area of about 35 km width giving an average extension rate of 6 2 mm yr across the central apennines the pattern of active deformation suggests active elastic strain accumulation on the westernmost of the two fault systems active in the late pleistocene holocene interval and may also suggest the presence of another active fault system not recognized so far

partitioned postseismic deformation associated with the 2009 mw 6 3 l aquila earthquake surface rupture measured using a terrestrial laser scanner using 3d terrestrial laser scan tls technology we have recorded postseismic deformation on and adjacent to the surface rupture formed during the 6th april 2009 l aquila normal faulting earthquake mw 6 3 using surface modeling techniques and repeated surveys 8 124 days after the earthquake we have produced a 4d dataset of postseismic deformation across a 3 65 m area at high horizontal spatial resolution we detected millimetre scale movements partitioned between discrete surface rupture slip and development of a hangingwall syncline over 10 s of meters we interpret the results as the signal of shallow afterslip in the fault zone we find 52 of the total postseismic hangingwall vertical motion occurs as deformation within 30 m of the surface rupture the total postseismic vertical motions are approximately 50 that of the coseismic we highlight the importance of quantifying partitioned postseismic contributions when applying empirical slip magnitude datasets to infer palaeoearthquake magnitudes

origin of hydrothermal cuznpb mineralisation in the olary block south australia evidence from fluid inclusions and sulphur isotopes abstract styles of sulphidic mineralisation recognised in the olary block south australia include disseminated to massive stratiform and stratabound occurrences as well as post peak metamorphic vein type mineralisation corresponding to the range of deposit types in the adjacent broken hill block however it is still unclear as to whether the epigenetic veins are genetically related to stratabound mineralisation in either of these two portions of the meso to palaeoproterozoic willyama inliers a fluid inclusion and sulphur isotope study was undertaken to examine the nature of fluids associated with epigenetic mineralisation in the olary block to determine possible genetic relationships between sulphides in epigenetic veins and stratabound mineralisation and to evaluate possible sources of sulphur in each of these occurrences fluid inclusions in epigenetic assemblages can be classified in general terms of co 2 rich ch 4 rich nacl rich and h 2 o rich types dense and moderately saline co 2 and ch 4 rich fluids prevailed during or shortly after peak metamorphism possibly as a result of metamorphic decarbonatisation and dehydration reactions at deeper levels as well as oxidation of graphite during retrograde metamorphism in shallower levels due to rehydration reactions and infiltration of metamorphic fluids from deep seated hydrothermal reservoirs during retrogression and uplift these fluids became increasingly saline and thus suitable to transport significant amounts of metals in solution near surface derived fluids entered fluid conduits during further uplift and cooling resulting in compositional dilution of the brines and decreasing fluid temperatures sulphur isotopic signatures in stratabound and epigenetic mineralisation in the olary block suggest a continuous supply of hydrothermal sulphur bearing fluids from a deep seated reservoir large scale leaching of volcaniclastics and other sedimentary rocks or convective homogenisation of a mixed source e g evaporitic or seawater sulphate and igneous sulphides resulted in relatively uniform 34 s values of 5 to 10 in the hydrothermal fluids mixing with sedimentary sulphur in stratabound occurrences is indicated by lighter sulphur isotopic compositions 34 s 15 6 in sulphides associated with carbonaceous pelites the distinct sulphur isotopic signature of epigenetic vein mineralisation in the olary block 34 s inpyrrhotite between 5 8 and 7 6 precludes simple derivation from pre existing deposits by remobilisation processes it rather implies extraction from the same source region at a later stage possibly induced by tectonic pumping and hydrothermal venting of a deep seated crustal reservoir

fault slip distribution of the 1999 mw 7 1 hector mine california earthquake estimated from satellite radar and gps measurements we use a combination of satellite radar and gps data to estimate the slip distribution of the 1999 m w 7 1 hector mine earthquake a right lateral strikeslip earthquake that occurred on a northwest southeast striking fault in the southern california mojave desert the data include synthetic aperture radar interferograms insar from both ascending and descending orbits radar amplitude image offset fields sario for both ascending and descending azimuth directions and campaign gps observations from 55 stations provided by agnew et al 2002 we model the fault with nine segments derived from the field mapped fault rupture the sario data and aftershock locations we first estimate the dip of each fault segment as well as a single constant strike slip component across each segment resulting in an average dip of 83 to the northeast and slip of up to 5 6 m then we fix the optimal fault segment dip discretize the fault segments into 1 5 km 1 5 km patches and solve for the variable slip distribution using a nonnegative least squares method that includes an appropriate degree of smoothing our preferred solution has both right lateral strike slip and reverse faulting the estimated geodetic moment is 5 93 10 19 n m m w 7 1 similar to seismological estimates indicating that there are insignificant interseismic and postseismic deformation signals in the data we find strike slip displacements of up to 6 0 m and reverse faulting of up to 1 6 m with the maximum slip located just northwest of the epicenter most of the slip is concentrated northwest and south of the epicenter little slip is found on the northeastern branch of the fault the sario data and our modeling indicate that the amount and extent of surface fault rupture were underestimated in the field

boron isotopic composition of marine and nonmarine evaporite borates abstract here we present the results of the boron isotopic analysis of borates from some well known marine and nonmarine evaporite deposits combining new analyses with analyses from the literature yields a mean 11 b value for nine marine evaporite borate analyses of 25 4 permil 11 b 10 b 4 15 0 02 and a mean for twenty five nonmarine evaporite borates of 7 10 permil 11 b 10 b 4 02 0 04 previous studies have shown that the boron isotopic composition of seawater 11 b 40 permil 11 b 10 b 4 20 is about four percent heavier than the boron isotopic composition of most crustal rocks and minerals we suggest that our results for marine and nonmarine evaporite borates reflect this difference thus it should be possible to use boron isotopic composition as a tracer for boron of marine evaporitic origin applications include borate bearing evaporite deposits and perhaps borate and or borosilicate bearing metamorphic rocks

boron isotope systematics of marine sediments abstract boron contents and boron isotopic compositions were determined for modern and ancient permian to miocene marine sediments including pelagic clay calcareous ooze siliceous ooze and neritic clay sediments 11b values of modern marine sediments range from 6 6 to 4 8 isotopic variation is controlled by the simple mixing of four major constituents detritus of continental origin marine smectite biogenic carbonates and biogenic silica detritus of continental origin with an average 11b value of 13 to 8 is the low 11b end member constituent of marine sediments and its boron is largely controlled by the concentration of illite which originates from wind or fluvial transport marine smectite biogenic carbonate and biogenic silica on the other hand represent the high 11b end members with 11b values of 2 3 to 9 2 8 0 to 26 2 and 2 1 to 4 5 respectively these high 11b values are the result of the equilibrium uptake of boron from seawater spatial variations in boron isotopes in the pacific sediments are essentially due to the distribution of the above four constituents although ancient argillaceous sediments shale and slate have boron contents that are identical with those of modern equivalents boron contents of limestone and chert are distinctly lower than those of modern calcareous and siliceous oozes ancient marine sediments have systematically lower 11b values 17 0 to 5 6 than those of the modern sediments the lower 11b values can be caused by diagenesis which induces 1 preferential removal of high 11b boron in calcium carbonate and silica during recrystallization and 2 boron isotopic exchange in the course of the smectite illite transition the observed boron isotopic compositions of ancient argillaceous sediments are distinctly different from those of fresh and altered morb therefore boron isotope systematics will be useful in identifying components from the descending oceanic slab involved in the formation of island arc magma and in investigating mantle crust recycling through subduction processes

water activity changes across an amphibolite granulite facies transition broken hill australia phase compositions in pelitic and mafic gneisses place tight constraints on pressure ranging from 3 up to 6 kb and to a lesser extent on temperature 500 up to 800 c during prograde regional metamorphism of the willyama complex broken hill se australia these limits allow an evaluation of water activity across the terrain using various equilibria in pelitic and mafic gneisses the stability of cummingtonite and biotite over much of the terrain places upper limits on temperature and the presence of syn metamorphic partial melts in the metasediments places lower limits on a h2o garnet biotitesillimanite k feldspar quartz relations combined with the partial melting data suggest a decrease in water activity from near 1 0 in the lower grade zones to 0 5 0 2 in the broken hill little broken hill part of the two pyroxene zone this result is compatible with less precise hornblende orthopyroxene clinopyroxene quartz relations

boron isotopic composition of tourmaline prismatine and grandidierite from granulite facies paragneisses in the larsemann hills prydz bay east antarctica evidence for a non marine evaporite source a unique assemblage of b rich rocks 2 wt b containing the borosilicate minerals tourmaline tur prismatine prs and grandidierite gdd is exposed in the ca 1000 ma brattstrand paragneiss in the larsemann hills east antarctica the b isotope composition of these three minerals in 21 paragneisses and 6 anatectic pegmatites were measured in situ using secondary ion mass spectrometry 11b ranges from 2 8 to 14 4 in tourmaline from 9 6 to 17 8 in prismatine and from 2 8 to 8 7 in grandidierite weighted uncertainties mostly 1 2 per sample in most cases average 11b increases in a given sample prs tur gdd whether the observed b isotope distribution has attained equilibrium were assessed using two criteria microstructural equilibrium and regular distribution of mg and fe in samples for which the two criteria are met we assume the measured distribution of isotopes 11ba b 11ba 11bb represents equilibrium 11btur prs 5 0 1 4 5 of 12 pairs 11btur gdd 3 3 0 8 3 of 5 pairs and 11bgdd prs 7 2 1 3 2 of 2 pairs consistent with the preference of 10b for tetrahedral sites prismatine and 11b for trigonal sites tourmaline grandidierite ab initio computations of b isotope fractionation factors 11btur prs 6 4 1 3 11btur gdd 1 8 1 1 and 11bgdd prs 8 2 1 1 provide confirmation of the measured fractionations the computed relaxed ionic structure of grandidierite gave a shorter 1 368 a b o bond length than in case of dravite 1 385 a which explains the measured enrichment of grandidierite in 11b relative to tourmaline the precursor of the b rich rock least changed by metamorphism tourmaline metaquartzite 11b tur 8 6 to 5 9 is interpreted to be a product of pre metamorphic hydrothermal b metasomatism boron sources consistent with this 11b range include oceanic crust clastic sediments volcanic rocks and non marine evaporite borate but not marine evaporite however dominance of metasediments in the brattstrand paragneiss major and trace element compositions of the b rich rocks and presence of abundant b are consistent with non marine evaporite being the most important source of b for the b rich lithologies of the larsemann hills a possible scenario for precursors of these rocks is a succession of clastic sediments in part tuffaceous intercalated with b rich evaporite deposits in a continental rift basin in which circulating hydrothermal fluids leached b from the evaporite and precipitated it as tourmaline in the associated clastic rocks to form the precursors to the tourmaline metaquartzites

space time distribution of afterslip following the 2009 l aquila earthquake 1 the inversion of multitemporal dinsar and gps measurements unravels the coseismic and postseismic afterslip slip distributions associated with the 2009 mw 6 3 l aquila earthquake and provides insights into the rheological properties and long term behavior of the responsible structure the paganica fault well resolved patches of high postseismic slip 10 20 cm appear to surround the main coseismic patch maximum slip 1 m through the entire seismogenic layer above the hypocenter without any obvious depth dependent control time series of postseismic displacement are well reproduced by an exponential function with best fit decay constants in the range of 20 40 days a sudden discontinuity in the evolution of released postseismic moment at 130 days after the main shock does not correlate with independent seismological and geodetic data and is attributed to residual noise in the insar time series the data are unable to resolve migration of afterslip along the fault probably because of the time interval six days between the main shock and the first radar acquisition surface fractures observed along the paganica fault follow the steepest gradients of postseismic line of sight satellite displacements and are consistent with a sudden and delayed failure of the shallow layer in response to upward tapering of slip the occurrence of afterslip at various levels through the entire seismogenic layer argues against exclusive depth dependent variations of frictional properties on the fault supporting the hypothesis of significant horizontal frictional heterogeneities and or geometrical complexities we support the hypothesis that such heterogeneities and complexities may be at the origin of the long term variable behavior suggested by the paleoseismological studies rupture of fault patches with dimensions similar to that activated in 2009 appears to have a 500 year recurrence time interval documented by paleoseismic and historical studies in addition to that paleoseismological evidence of large 0 5 m coseismic offsets seems to require seismic events recurring every 1000 2000 years characterized by 1 multisegment linkage 2 surface ruptures larger than in 2009 and 3 complete failure of the 2009 coseismic and postseismic patches

earthquake ground effects and intensity of the 16 april 2016 mw 7 8 pedernales ecuador earthquake implications for the source characterization of large subduction earthquakes

sulphide mineralisation in the olary block south australia the south australian portion of the willyama inliers hosts a diversity of small sulphide and uranium deposits and numerous outcropping gossans this fact together with geological similarities to the adjacent broken hill block has led to extensive exploration a broad classification distinguishes two main types of sulphide mineralisation 1 stratiform iron sulphide dominated cu zn co deposits which occur widespread within specific stratigraphic intervals and stratabound occurrences of syn depositional to diagenetic origin which show some structural control 2 syn tectonic to post peak metamorphic replacement and vein type deposits fe cu au and cu zn pb which are hosted by fractures and within faults and shear zones these occurrences show no stratigraphic control and are not spatially related to type 1 mineralisation late stage deposits also differ from stratiform stratabound mineralisation in their texture mineral assemblage and geochemical composition much of the sulphide mineralisation in the olary block has been interpreted as resulting from rift associated syn to diagenetic processes such as hot spring exhalations and base metal precipitation along reduction oxidation interfaces subsequent granitic intrusive high grade metamorphic and multiphase deformation events would have induced remobilisation and redeposition of sulphides in a variety of epigenetic modes however a detailed petrographic and geochemical study of sulphide mineralisation in the olary block demonstrates that due to the lack of abundant pervasive fluids translocation and modification of preexisting sulphides were restricted to less than a few centimetres instead widespread syn tectonic to epigenetic i e post peak metamorphic mobilisation of ore constituents occurred to form retrograde sulphide mineralisation as well as multiple generations of late stage vein deposits these epigenetic deposits are genetically unrelated to synsedimentary and diagenetic occurrences an aspect of significance for exploration in the olary block temporal separation of peak metamorphism in deeper crustal levels from its occurrence in shallow levels periodic tectonic disturbances and repeated seismic pumping are processes believed to have resulted in intermittent mobilisation of ore constituents from a deep seated metasedimentary reservoir

locating distributed faulting contributions from insar imaging to probabilistic fault displacement hazard analysis pfdha abstract prediction of location and amount of slip for distributed faulting associated to strong earthquakes is a recently explored issue with major implications in terms of hazard assessment currently the best practice involves the applications of probabilistic fault displacement hazard analysis pfdha whose results fit sufficiently well real data in the near range of the primary fault but show considerable inaccuracies in the far range we believe that this inaccuracy descends from the biased earthquake databases used for regression analysis whose data relative to old earthquakes were largely collected only by field surveys focused close to the primary fault i e near range remotely sensed data i e interferometric radar imaging insar offer the opportunity to precisely measure the surface deformation induced by strong earthquakes and thus to explore its possible relation with distributed faulting we analyze the l aquila earthquake case study 29th april 2009 mw 6 3 and explore the correlation between location and slip on distributed faulting and insar derived deformation field we find a significant correlation between occurrence of distributed faulting and profile curvature of the dislocation field in spite of the distance from the primary fault moreover distributed faults tend to occur within the area deformed by the earthquake as imaged by insar data and whose extent is directly proportional to the earthquake magnitude mw according to a dataset of 30 recent earthquakes we then propose that these observations have to be incorporated into the present pfdha practice as limit boundaries to possible scenarios of probabilistic analysis and that an integrated use of field based and remotely data collection have to be implemented following strong earthquakes

chemical and boron isotopic compositions of tourmaline from the archean big bell and mount gibson gold deposits murchison province yilgarn craton western australia abstract tourmaline is a commonly found gangue mineral in archean greenstone belt lode gold deposits worldwide in this paper we report major trace and rare earth element ree and boron isotopic compositions of tourmaline from two major amphibolite grade archean gold deposits big bell and mount gibson murchison province yilgarn craton western australia in an attempt to better understand the hydrothermal gold formation processes that were also responsible for tourmalinization tourmalines in these two major deposits all belong to the dravite schorl series and tend to be mg rich where closely associated with gold and sulfide ores the ore related tourmalines also contain high concentrations of ore metals such as au ag pb and cu in the big bell deposit tourmalines occur along the foliation in lode schists and show low fe fe mg ratios of 0 11 0 30 tio 2 contents of 0 15 0 73 wt and negligible mno 11 b values of 17 7 to 15 0 in the mount gibson deposit the tourmalines closely associated with the sulfide ores are the most mg rich with low fe fe mg ratios of 0 19 0 22 while tourmalines from garnet bearing biotite muscovite schists that overly the lode gold orebody are more fe rich fe fe mg 0 30 0 63 tourmalines from an amphibolite schist are mg rich with fe fe mg ratios 0 27 0 34 that lie between the above two groups of tourmalines the compositional trend from fe rich tourmalines in the sulfide poor schists to mg rich in the sulfide ores at mount gibson is similar to that observed in massive sulfide ore deposits worldwide alternatively the mg rich nature of the sulfide related tourmalines may be due to metamorphic reactions that are accompanied by fe incorporation into sulfides leaving coexisting silicates more mg rich the ree geochemistry of the tourmalines from the mount gibson ore zone schists displays strong hree enrichments and positive eu anomalies with eu eu ratios up to 2 4 which are similar to tourmalines associated with massive sulfide deposits the ore related tourmalines disseminated in the host schists show 11 b values of 18 6 to 17 0 whereas one coarse grained tourmaline vein has a lower 11 b value of 21 9 to 21 4 these data support hypotheses which suggest that the schists that host the gold mineralization are the metamorphosed equivalents of a base metal rich hydrothermally altered seafloor horizon that is typical of vms style mineralization with the boron possibly derived from leaching of footwall sedimentary and volcanic rocks during hydrothermal circulation

boron isotopic composition of tourmaline from massive sulfide deposits and tourmalinites boron isotope ratios 11b 10b have been measured on 60 tourmaline separates from over 40 massive sulfide deposits and tourmalinites from a variety of geologic and tectonic settings the coverage of these localities is global 5 continents and includes the giant ore bodies at kidd creek and sullivan canada broken hill australia and ducktown usa overall the tourmalines display a wide range in 11b values from 22 8 to 18 3 possible controls over the boron isotopic composition of the tourmalines include 1 composition of the boron source 2 regional metamorphism 3 water rock ratios 4 seawater entrainment 5 temperature of formation and 6 secular variations in seawater 11b the most significant control appears to be the composition of the boron source particularly the nature of footwall lithologies variations in water rock ratios and seawater entrainment are of secondary importance the boron isotope values seem especially sensitive to the presence of evaporites marine and non marine and carbonates in source rocks to the massive sulfide deposits and tourmalinites

meta evaporite sequence exhalative chemical sediments and associated rocks in the proterozoic willyama supergroup south australia implications for metallogenesis abstract the willyama supergroup comprises proterozoic meta sedimentary and meta igneous rocks in western new south wales and eastern south australia and contains the giant broken hill pb zn ag deposit in addition to numerous small stratiform stratabound and vein mineral deposits new lithological geochemical and fluid inclusion data from the olary block west of broken hill suggest the presence of former evaporite rocks now metamorphosed to a variety of chemically and mineralogically unusual lithologies these evaporite rocks overlie relatively oxidised strata and are in turn overlain by reduced graphite bearing pelites rocks of sodic composition abound represented by albite quartz rich rocks calcite actinolite epidote garnet clinopyroxene inferred to represent metamorphosed analcime rich strata of felsic volcaniclastic provenance with variable proportions of carbonates for example calcite dolomite trona and shortite these rocks are interspersed with potassic rocks possibly also with an evaporitic origin in addition to normal clastic meta sediments the presence of halogen rich minerals in a distinctive mineral assemblage hypersaline fluid inclusions pseudomorphic voids and minerals after gypsum and carbonate in addition to tourmalines with isotopically light boron isotopes is interpreted as evidence for a non marine evaporite parent rock for portions of the olary block types of mineral occurrences in the olary block form a continuum between chemical sediments formed by the exhalations of hydrothermal fluids to intrasediment deposits inferred to have been formed due to the chemical changes imposed on these and or diagenetic fluids during their passage through the sedimentary pile disseminated stratabound pyrite including cobaltian types and chalcopyrite extend along strike for many kilometres and are interpreted to have formed by a diagenetic mechanism the presence of massive sulphide bearing strata iron formations barite tourmalinite and manganiferous rocks are typical of chemical sediments derived from hot spring sources the olary block meta evaporites have similar whole rock compositions to tertiary analcime rich rocks of the green river formation wyoming these new data imply that portions of the adjacent broken hill block may also comprise meta evaporites for example the quartz albite rich strata of the thackaringa group and the calcsilicates of the lower broken hill group and that the disseminated cobaltian pyrite mineralisation in the thackaringa group may not be of exhalative origin

fault identification for buried strike slip earthquakes using insar the 1994 and 2004 al hoceima morocco earthquakes summary the 1994 m w 6 0 and 2004 m w 6 5 al hoceima earthquakes are the largest to have occurred in morocco for 100 yr and give valuable insight into the poorly understood tectonics of the area bodywave modelling indicates the earthquakes occurred on near vertical strike slip faults with the nodal planes oriented nw se and ne sw distinguishing between the primary fault plane and auxiliary planes using either geodetic or seismic data is difficult due to the spatial symmetry in deformation fields and radiation pattern of moderately sized buried strikeslip earthquakes preliminary studies using aftershock locations and surface observations have been unable to identify the orientation of the primary fault plane for either earthquake conclusively we use radar interferometry and aftershock relocation of the earthquake sequence to resolve the ambiguity for the 2004 earthquake inverting the interferograms for a uniform slip model based either of the two potential nodal planes results in similar misfits to the data however the ne sw best fit fault plane has an unrealistically high fault slip to length ratio and we conclude the nw se striking nodal plane is the primary fault plane and slip was right lateral we carry out tests on synthetic data for a buried strike slip earthquake in which the orientation of the fault plane is known a priori independent of geometry missing data and correlated noise models produced assuming the auxiliary plane to be the fault plane have very high fault slip to length ratios the 1994 earthquake had a smaller magnitude and comparisons of model misfits and slip to length ratios do not conclusively indicate which of the nodal planes is the primary fault plane nonetheless the insar data provides valuable information by improving the accuracy of the earthquake location by an order of magnitude we carry out a multiple event relocation of the entire earthquake sequence including aftershocks making use of the absolute locations for the 1994 and 2004 main shocks from our insar study the aftershock locations are consistent with a nw se orientated fault plane in 2004 and suggests that the 1994 earthquake occurred on a ne sw fault perpendicular to the fault which ruptured in 2004 previous tectonic models of the area proposed a bookshelf model of block rotation with nne ssw left lateral faults this model requires modification to accommodate the observation of right lateral slip on a nw se fault plane for the 2004 earthquake and we prefer to interpret the fault orientations as due to a zone of distributed shear with a right lateral fault striking at 115 and conjugate clockwise rotating left lateral faults striking at 25

a reconnaissance of the boron isotopic composition of tourmaline abstract a preliminary investigation of the boron isotopic composition of tourmaline from some boron rich associations has been made the results for tourmaline from metasedimentary parageneses n 12 range from 11b 22 to 22 per mil these data mainly fall between the boron isotopic compositions of normal marine sediments with 11b 2 to 5 per mil and seawater with 11b 39 5 per mil tourmaline samples from granitic pegmatites n 6 on the other hand range from 11b 12 to 5 per mil the data provide a rudimentary indication of the range of boron isotopic variation in tourmaline some of the processes leading to this range and some possible geochemical tracer applications

trench investigations of the 1915 fucino earthquake fault scarps abruzzo central italy geological evidence of large historical events earthquake hazard analyses in italy are mainly based on historical seismic catalogs however the completeness of the italian catalog which spans more than 2000 years progressivcly decreases going back in time in the fucino basin historical research has not produced evidence of large earthquakes before the january 13 1915 event m s 7 0 33 000 people killed this event generated surface faulting along at least two parallel quaternary normal faults bounding the eastern side of the basin the celano gioia and parasano cerchio faults over an end to end length of about 23 km with a downthrow of 30 90 cm toward southwest to improve geological aspects of the seismic history of this area we trenched onc of the coseismic scarps along the celano gioia fault at a trench site near the village of san benedetto de marsi the fault traverses the area formerly covered by the fucino lake drained for farming in 1875 a d the evidence collected in the trenchcs suggests at least two large events in historical times before 1915 radiocarbon dates constrain the age of event b between the 6th and the 9th centuries a d possibly coinciding with the cvent felt in rome in 801 a d molin arid guidoboni 1989 event a probably occurred after the 10th ccntury a d and almost certainly before the 1349 a d earthquake because historical studies show 1 that event a was not produced during the earthquake sequence that occurred in central italy in 1349 a d molin and guidoboni 1989 and 2 that the post 1349 seismic catalog can be regarded as complete for surface faulting earthquakes surface displacements determined for events a and b compared to the 1915 surface faulting indicate that m 6 5 earthquakes were associated with each rupturc these obscrvations suggest that the return period for large earthquakes in the fucino basin is shorter than that indicated by the historical record alone the fucino example clearly shows that thc cxceptionally long historical record in italy is still inadequate for a comprehcnsive seismic hazard characterization

the sedimentary cycle of the boron isotopes abstract marine sediments contain two isotopically distinct components a non desorbable fraction with 11b between 4 3 and 2 8 per mil n 10 and a desorbable component with 11b between 13 9 and 15 8 per mil n 6 the adsorption coefficient k for the uptake of b from seawater by fluvial suspended material mississippi has an experimentally determined value of 1 54 0 05 the associated isotope fractionation factor is 0 974 0 003 empirical values for k determined from the analysis of marine sediments n 6 were between 3 and 4 the amount of b adsorbed onto fluvial suspended material during estuarine mixing is about 9 109 moles yr based on pore water data adsorption experiments and comparative size fraction analyses suspended sediments from the mississippi river vs bottom deposits from the delta there is no evidence for the incorporation of b into detrital sediments at low temperature however the high b content of bauer deep metalliferous sediments must be due to incorporation of seawater b during formation of authigenic silicates the 11b of these minerals is 2 3 per mil hydrothermally altered sediments from dsdp hole 477 guaymas basin gulf of california have variable b contents from 33 ppm similar to the unaltered detritus to 1 2 ppm in the recrystallized material the latter has 11b as low as 9 0 per mil substantially lower than the unaltered material hydrothermal solutions collected from vents adjacent to the hole have boron contents elevated by about a factor of 4 relative to seawater and 11b between 16 5 and 23 2 per mil the b mobilized from the sediments is isotopically fractionated with the fluids being preferentially enriched in the heavy isotope analysis of an oxisol profile developed over granite in the guyana shield showed that boron is partially mobilized during weathering with an isotopic offset of 2 5 per mil between bedrock and soil the observed enrichment of b in shales relative to igneous rocks does not occur during weathering or during exposure to seawater at low temperature incorporation occurs only during burial diagenesis at temperatures greater than about 60 c however the enrichments cannot be attained during a single cycle of primary weathering and burial but must be cumulative over many cycles

active tectonics of the adriatic region from gps and earthquake slip vectors 1 to investigate the kinematics of the adriatic region we integrate continuous and episodic gps measurements with mw 4 5 earthquake slip vectors selected from the regional centroid moment tensor catalogue coherent motion of gps sites in the po valley in apulia and in the hyblean plateau allows us to estimate geodetically constrained angular velocities for these regions the predictions of the gps inferred angular velocities are compared with the earthquake slip vectors showing that the seismically expressed deformation at the microplate boundaries is consistent with the observed geodetic motion the remarkable consistency between geodetic seismological and geological evidence of active tectonics suggests that active deformation in the central adriatic is controlled by the relative motion between the adria and apulia microplates the microplates angular rotation rates are then compared with the rotation rates calculated with a simple block model supporting the hypotheses 1 that apulia forms a single microplate with the ionian sea and possibly with the hyblean region and 2 that adria and apulia rotate in such a way as to accommodate the eurasia nubia relative motion we suggest that the present day microplate configuration follows a recent fragmentation of the adriatic promontory that during the neogene rigidly transferred the africa motion to the orogenic belts that now surround the adriatic region

stratiform tourmalinites in metamorphic terranes and their geologic significance stratiform tourmalinites are significant minor rock types in many regional metamorphic terranes of the world tourmalinites are more widespread than previously recognized and are especially common in proterozoic and early paleozoic sequences dominated by clastic metasedimentary rocks they consist of conformable layers made up primarily of quartz and abundant tourmaline the latter typically exceeding 15 to 20 of rock volumes a few tourmalinites display striking sedimentary structures such as graded bedding cross laminations slump and flame structures and rip up clasts these and other geologic features provide important constraints for assessing the origin of these rocks and they suggest that tourmalinites form by the early diagenetic modification of a primary boron rich chemical precipitate tourmalinites are significant in preserving a valuable record of unusual chemical and paleogeographic conditions in clastic sedimentary basins and in their close association with a variety of stratabound mineral deposits

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

surface faulting of the 6 april 2009 mw 6 3 l aquila earthquake in central italy this paper documents evidence of surface faulting associated with the 6 april 2009 moderate sized earthquake ml 5 8 mw 6 3 in the central apennines of italy which caused major damage to the town of l aquila and its surroundings coseismic surface ruptures were mapped for a minimum distance of 2 6 km along the paganica fault a fault still poorly investigated relative to the other active faults nearby which bound much wider range fronts surface rupture length srl and maximum displacement parameters 2 6 km minimum and 10 15 cm respectively are in agreement with what is expected for an mw 6 3 event in the italian apennines tectonic environment different viewpoints exist on the amount of srl and the number of activated faults we propose a pattern of sympathetic and secondary slip on an array of faults around the master seismogenic structure past seismicity and evidence for larger holocene offsets on this and other capable faults nearby prove that the 2009 event is not a good reference event for assessing the seismic hazard of the region nevertheless the 2009 l aquila earthquake once more confirmed the importance of detailed geological studies for a proper seismic hazard assessment and it clearly illustrates the need to pay attention to moderate events and supposedly minor active faults indeed this type of earthquake is rather frequent in the whole mediterranean region and is potentially much more destructive than in the past due to the expanding urban centers and infrastructures inside their epicentral regions and even right above the traces of capable faults

seismic and aseismic slip evolution and deformation associated with the 2009 2010 northern malawi earthquake swarm east african rift summary interferometric synthetic aperture radar insar measurements field observations and elastic modelling of the 2009 2010 karonga northern malawi earthquake swarm reveal widespread coseismic and localized post seismic deformation in a period of about 1 5 months starting on november 5 29 m 4 earthquakes struck the region culminating in an mw 6 peak event on december 19 the next few months were characterized by significant localized deformation with a very low seismic moment release we find a very good agreement between insar and field observations of surface ruptures our best fitted coseismic models indicate dip slip displacements on a fault dipping 40 to the southwest with maximum slip of about 120 cm at 3 5 km depth fault activity continued until 2010 august as shallow aseismic afterslip mostly above the maximum coseismic slip patches although the swarm occurred within a coastal plain covered by porous quaternary sediments and a high water table the effect of poroelastic relaxation on the post seismic deformation was found to be negligibly small in contrast with other recent earthquake swarms along the east african rift the karonga swarm shows no evidence for dike intrusion

marine evaporites from an oceanic island in the neoproterozoic adamastor ocean abstract we report a hitherto unknown occurrence of ancient neoproterozoic evaporite deposits from an allochthonous terrane in the pan african gariep belt in namibia low contents of rb cs ba zr hf th and u flat chondrite normalised rare earth element ree patterns 87 sr 86 sr ratios as low as 0 7075 na cl br systematics of fluid inclusion leachates and high 11 b values for stratiform tourmalinites together with geologic evidence such as association with oceanic basalt gabbro and stromatolitic dolomite point to a marine evaporitic origin an atoll environment on an oceanic island is envisaged as a likely depositional setting in the associated mafic sequence we found a diamictite with metre sized ice rafted detritus suggesting the presence of sea ice cover at relatively low latitude around the time of evaporite deposition based on chemostratigraphic 87 sr 86 sr 13 c comparison with passive continental margin sediments in the para autochthonous external part of the gariep belt a correlation of the mafic diamicitite with the global varangian 590 560 ma glaciation is proposed

tourmaline as a recorder of contrasting boron source and potential tin mineralization in the mopanshan pluton from inner mongolia northeastern china abstract abundant tourmaline occurs in the mopanshan pluton in inner mongolia of ne china and can be classified by its occurrence into four types nodular tourmalines nd type pegmatite pocket tourmalines pp type stockwork tourmalines sw type and vein tourmalines vt type all these tourmalines belong to the alkali group and are dravite schorl petrography and major elements data suggest that the nd and pp type tourmalines crystallized during the transition from late magmatic to early hydrothermal evolution of granite with all the components derived from the magma petrography and trace elements especially sr v cr ni ti data suggest that the sw and vt type tourmalines may form by the mixing of magmatic and country rocks components in the post magmatic hydrothermal environment due to the similar 11b of the sw type with the nd and pp type tourmalines variation

the 2009 l aquila earthquake central italy a source mechanism and implications for seismic hazard an edited version of this paper was published by agu copyright 2009 american geophysical union

shallow subsurface structure of the 2009 april 6 mw 6 3 l aquila earthquake surface rupture at paganica investigated with ground penetrating radar p the shallow subsurface structure of the 2009 april 6 m w 6 3 l aquila earthquake surface rupture at paganica has been investigated with ground penetrating radar to study how the surface rupture relates spatially to previous surface displacements during the holocene and pleistocene the discontinuous surface rupture stepped between en echelon parallel faults within the overall fault zone that show clear holocene pleistocene offsets in the top 10 m of the subsurface some portions of the fault zone that show clear holocene offsets were not ruptured in 2009 having been bypassed as the rupture stepped across a relay zone onto a fault across strike the slip vectors defined by opening directions across surface cracks indicate dip slip normal movement whose azimuth remained constant between 210 degrees and 228 degrees across the zone where the rupture stepped between faults we interpret maximum vertical offsets of the base of the holocene summed across strike to be 4 5 m which if averaged over 15 kyr gives a maximum throw rate of 0 23 0 30 mm yr 1 consistent with throw rates implied by vertical offsets of a layer whose age we assume to be similar to 33 ka this compares with published values of 0 4 mm yr 1 for a minimum slip rate implied by offsets of middle pleistocene tephras and 0 24 mm yr 1 since 24 8 kyr from palaeoseismology the paganica fault although clearly an important active structure is not slipping fast enough to accommodate all of the 3 5 mm yr 1 of extension across this sector of the apennines other neighbouring range bounding active normal faults also have a role to play in the seismic hazard