constant concentration boundary condition lessons from the hydrocoin variable density groundwater benchmark problem in a solute transport model if a constant concentration boundary condition is applied at a node in an active flow field a solute flux can occur by both advective and dispersive processes the potential for advective release is demonstrated by reexamining the hydrologic code intercomparison hydrocoin project case 5 problem which represents a salt dome overlain by a shallow groundwater system the resulting flow field includes significant salinity and fluid density variations several independent teams simulated this problem using finite difference or finite element numerical models we applied a method of characteristics model mocdense the previous numerical implementations by hydrocoin teams of a constant concentration boundary to represent salt release by lateral dispersion only as stipulated in the original problem definition was flawed because this boundary condition allows the release of salt into the flow field by both dispersion and advection when the constant concentration boundary is modified to allow salt release by dispersion only significantly less salt is released into the flow field the calculated brine distribution for case 5 depends very little on which numerical model is used as long as the selected model is solving the proper equations instead the accuracy of the solution depends strongly on the proper conceptualization of the problem including the detailed design of the constant concentration boundary condition the importance and sensitivity to the manner of specification of this boundary does not appear to have been recognized previously in the analysis of this problem

variable density flow and solute transport simulation of regional aquifers containing a narrow freshwater saltwater transition zone variable density flow and solute transport simulation of aquifer systems containing narrow transition zones between freshwater and saltwater requires particular attention to certain aspects of the numerical method and its application to be successful typically only cases involving wide transition zones have been simulated with variable density transport models possibly because of inaccuracies in the modeling approaches used the major components of a successful approach are threefold first functionally consistent approximation of terms involved in fluid velocity calculations is necessary in the case of galerkin finite element methodology a significant modification is required to the standard approach in order to achieve consistency second the simulator must be verified in a particular series of tests the usual tests using henry s problem for verification of density dependent transport simulators are inadequate to check for consistency of the velocity approximations and for the accuracy of simulating flow driven by bouyancy forces third adequately fine spatial discretization is required when applying the simulator for spatial stability of the numerical transport solution and to allow accurate representation of narrow transition zones and the effects of low transverse dispersivity the effectiveness of this approach is demonstrated through simulation of the flow of fresh and saline groundwater in the layered basalt aquifer of southern oahu hawaii the transition zone in this regional flow system is narrow except near the discharge area where it is broadly dispersed simulation of this common situation with an inconsistent approximation gives grossly incorrect results while simulation with a consistent model provides a robust tool for analysis of system hydrology

long term stability of flow path structure in crystalline rocks distributed in an orogenic belt japan most evaluations of the contaminant retardation processes likely to be important in geological disposal e g for high level radioactive waste hlw consider only the present characteristics of fractures and associated mineral infills relatively little attention has been given to possible long term changes in these features and their influence on groundwater flow the work reported here seeks to provide analogous evidence that such changes are not likely to be important and hence to improve confidence in the presently adopted evaluation methodology and its long term applicability in the orogenic belt that is formed by the japanese islands there are wide areas of crystalline rock the rocks in each area have a distinctive age sequence which is partly reflected in the characteristics of the fracture systems and associated mineral fillings that occur these characteristics generally imply that groundwater and solutes can be conducted through fracture networks except in the cases of fault zones or crushed zones the structural and mineralogical features of these networks readily illustrate how certain contaminants might react and be retarded by the fracture fillings and open pore geometry due to chemical sorption and or physical retardation here we describe the fracture systems developed in crystalline rocks with different ages that are intruded into the japanese orogenic belt the aim is to build a model for the long term fracturing process and hence to evaluate fracture dstabilityt i n particular the comparisons are made between the fracture geometries and the frequencies observed in the 1 9 0 8 ma takidani granodiorite the youngest exposed pluton in the world the ca 67 ma toki granite and the ca 117 ma kurihashi granodiorite located in central to northwest japan the observations show that all these crystalline rocks have similar fracture frequencies with 1 to 2 fractures per meter in the massive part of rock bodies mineralogical studies and dating analyses of fracture fillings also suggest that fractures are relatively physically stable major new fractures tend not to be created in the massive part of rock bodies even when a pluton has been subjected to the regional stresses of plate movements with a duration of about 100 ma the results show the unique characteristics of the fracture forming process and the relatively stable geometries of fracture network systems in crystalline rocks distributed within the orogenic belt this analogue also enables us to provide a model to build confidence in a technical approach applicable for modeling of hydrogeology and geology over long time scales under the

deformation processes adjacent to active faults examples from eastern california 1 major seismogenic faults are embedded within narrow zones of inelastic off fault deformation ofd where both distributed displacement and modification of rock properties occur active distributed displacement may affect slip rate estimates seismic energy radiation and geodynamic models this study addresses the role of ofd in the displacement history and mechanical behavior of seismogenic faults by multisite study of deformed geologic features adjacent to 30 60 km long active strike slip faults of 10 km of dextral displacement in the mojave desert eastern california we find that distributed displacement accommodates 0 to 25 of the total displacement over zones of one to two kilometers width displacement occurs mostly within 100 200 m of faults and decreases nonlinearly away from the main fault we show evidence for distributed displacement through simple shear in the form of parallel secondary faults and progressive deformation of linear markers adjacent to the calico fault we also find evidence for shear via rotation and progressive fragmentation adjacent to the harper lake fault analysis of block dimensions show that blocks tend to decrease in size toward faults and that cumulative length of secondary faults is longer than the main fault by at least a factor of 10 based on crosscutting relationships and the relationship of ofd to geophysically imaged compliant zones around active faults we argue that distributed displacement is an active process and suggest that zones of diminished rigidity near faults may be at least in part driven by secondary faulting during the rupture propagation along the main fault

microfracturing paleostress and the growth of faults abstract we have analyzed the microfractures in samples taken near one thrust fault and five normal faults of known displacement to test the dependence of microfracture density and distribution on fault slip we have also recorded the orientation of microfractures as a function of distance from the associated fault surface in order to control as many parameters as possible shallow faults with similar lithologies were chosen they showed the same kind of deformation namely microfracturing without block rotation recrystallization extensive granulation or crystal plasticity the results of over 8000 microfracture measurements suggest that maximum microfracture density is independent of net slip we interpret this relationship as indicating that the preponderance of microfracturing occurs in proximity to the propagating fault tip the angular relationship between the shear plane and microfractures was commonly found to be between 5 and 20 significantly less than the 30 expected between the far field maximum principal stress and the shear surface this low angle between microfracture orientation and shear plane orientation is predicted for a local stress field associated with a propagating mode ii fault tip other possible explanations for the small angle for tensional microfractures and the shear surface are 1 the effective confining pressure was very low or 2 shear strength at failure was much larger than expected

silica diagenesis ii general mechanisms abstract amorphous silica phases opal a precipitate in nature due to the formation of dense colloids in supersaturated alkaline aqueous solutions with low relative concentrations of other ions opal a dissolves and yields solutions of still relatively high silica content in pore waters containing abundant cations open framework polymers form which flocculate to yield opal ct opal ct becomes increasingly ordered primarily due to preferential growth of cristobalite relative to tridymite and crystal size increase opal ct dissolves to yield pore waters of low silica concentration which allows slow growth of quartz crystals from monomeric solution the quartz crystals then slowly increase in size and crystallinity carbonates appear to enhance opal ct formation possibly due to the activity of positively charged hydroxyl complexes hence polymerization in relatively pure systems is involved in opal a formation and polymerization in impure systems is involved in opal ct formation and slow growth from monomeric low silica concentration solutions is involved in precipitation of quartz in sedimentary realms

fluid rock reaction weakening of fault zones the presence of weak phyllosilicates may explain the low shear strengths of fault zones if they define well developed fabrics the growth of phyllosilicates is favored in meteoric water dominated granitic fault systems where mineral aqueous fluid equilibria predict that modal phyllosilicate will increase via feldspar replacement reactions in deeper more alkaline rock dominated regimes the reactions reverse and feldspars tend to replace phyllosilicates in mg rich mafic rocks however phyllosilicates chlorite biotite can replace stronger framework and chain silicates in both shallower approximately 10 km meteoric h sub 2 o dominated and in deeper alkaline rock dominated regimes where these phyllosilicates precipitate in active fault zones they contribute directly to reaction softening because low temperature deformation of phyllosilicates is not governed by frictional processes alone but can occur by pressure independent dislocation glide the strength of phyllosilicate rich fault rocks can be low at all depths low strain rate creep during interseismic periods can align phyllosilicate grains in foliated gouge and phyllonites where preferred orientations are strong and contiguity of phyllosilicates is large strengths of rocks within fault zones may approach minimum strengths defined by single phyllosilicate crystals fault zones containing localized high concentrations of phyllosilicates with strong preferred orientations in well defined folia can exhibit aseismic slip especially where mafic mg rich rocksmore occur along the fault like parts of the san andreas fault 104 refs 6 figs 1 tab less

tropical extratropical geopotential height teleconnections during the northern hemisphere winter abstract simultaneous and lagged correlation statistics have been calculated between time series of seasonal height anomalies at selected stations and extratropical grid point anomalies in both hemispheres the tropical stations in two major tropical precipitation zones the indo china maritime continent and africa are well correlated with each other these stations are also correlated with stations in the north pacific and australia but the coefficients are smaller the correlations between height anomalies at any of these stations and northern hemisphere height anomalies show a well defined global pattern depending upon the location of the stations the pattern is either a pacific north american pna a tropical northern hemisphere tnh pattern or a mixed pattern having both elements all three patterns pna tnh and wpo western pacific oscillation have been linked to tropical variations the correlations between height anomalies at these well correlated stations and the southern hemisphere heig

the block structure and quaternary strike slip block rotation of central japan central japan is situated on the inflection point of the bow shaped japanese islands numerous nw se trending active faults arranged in parallel at intervals of 20 to 80 km are found in this area these active faults are more than 30 km long with shattered zones from 30 to 300 m wide several active faults constitute a given block boundary which serves as the dividing line for one of the four blocks that make up central japan the block boundaries require careful study since numerous historical earth quakes have occurred along these lines offset measurements of basement rocks created during the quaternary period due to left lateral faulting amount to 1 to 7 km gravity lineaments which link points of sudden change and saddles of bouguer anomalies are clearly found along the block boundaries the nw se trending active faults appearing on the ground surface are associated with motions of the block boundaries block rotational movement caused by left lateral faulting plays an important role in the crustal deformation of central japan rotational angles of the blocks calculated from the amount of displacement of basement rocks initiated during the quaternary period are estimated to be 3 to 7 in a clockwise manner

the east atlantic west russia ea wr teleconnection in the north atlantic climate impact and relation to rossby wave propagation large scale winter teleconnection of the east atlantic west russia ea wr over the atlantic and surrounding regions is examined in order to quantify its impacts on temperature and precipitation and identify the physical mechanisms responsible for its existence a rotated empirical orthogonal function analysis of the upper tropospheric monthly height field captures successfully the ea wr pattern and its interannual variation with the north atlantic oscillation nao as the first mode ea wr s climate impact extends from eastern north america to eurasia the positive negative ea wr produces positive negative temperature anomalies over the eastern us western europe and russia east of caspian sea with negative positive anomalies over eastern canada eastern europe including ural mountains northeastern africa and the middle east these anomalies are largely explained by lower tropospheric temperature advections positive negative precipitation anomalies are found over the mid latitude atlantic and central russia around 60 e where lower level cyclonic anticyclonic circulation anomaly is dominant eastern canada and western europe including the mediterranean region are characterized by negative positive precipitation anomalies the ea wr is found to be closely associated with rossby wave propagation wave activity fluxes show that it is strongly tied to large scale stationary waves furthermore a stationary wave model swm forced with vorticity transients in the mid latitude atlantic 40 n or diabatic heat source over the subtropical atlantic near the caribbean sea produces well organized ea wr like wave patterns respectively sensitivity tests with the swm indicate enhancement of ea wr like blocking over west of scandinavia when the mean state is modified to have a positive nao component that enhances upper level westerlies between 40 and 60 n

implications of mylonitic microstructures for the geotectonic evolution of the median tectonic line central japan the median tectonic line mtl the most prominent onshore fault in japan demarcates the cretaceous hiji quartz dioritic gneiss of the ryoke belt on the west from the high p t type sambagawa metamorphic rocks on the east in the takato area toward the mtl the hiji gneiss grades into strongly mylonitized rocks characterized by grain size reduction of quartz in the mylonitic rocks the development of fluxion banding sm is remarkably influenced by the existence of k feldspar forming a myrmekitic intergrowth brittle microstructures indicative of truly cataclastic deformation are observed only in mylonitic rocks close to the mtl early deep level ductile deformation apparently gave way to shallower brittle deformation at a later stage the attitude of stretching lineations lm and asymmetric microstructures observed in the mylonites suggest that sinistral strike slip shearing with a subordinate component of vertical slip took place during mylonitization in mid cretaceous time the mylonitic rocks and their protolith supposed to have constituted the eastern limb of the shear zone were probably eroded out and lost by upheaval of the sambagawa belt relative to the ryoke belt

teleconnections in the geopotential height field during the northern hemisphere winter abstract contemporaneous correlations between geopotential heights on a given pressure surface at widely separated points on earth referred to as teleconnections in this paper are studied in an attempt to identify and document recurrent spatial patterns which might be indicative of standing oscillations in the planetary waves during the northern hemisphere winter with time scales on the order of a month or longer a review of existing literature on the subject reveals the existence of at least four such patterns the north atlantic and north pacific oscillations identified by walker and bliss 1932 a zonally symmetric seesaw between sea level pressures in polar and temperature latitudes first noted by lorenz 1951 and what we will refer to as the pacific north american pattern which has been known to operational long range forecasters in this country since the 1950 s a data set consisting of nmc monthly mean sea level pressure and 500 mb height analyses for a 15 year period is used as a basis fo

groundwater mixing dynamics at a canadian shield mine temporal and spatial variations in geochemistry and isotopes in mine inflows at the con mine yellowknife are studied to access the impact of underground openings on deep groundwater flow in the canadian shield periodic sampling of inflow at 20 sites from 700 to 1615 m depth showed that salinities range from 1 4 to 290 g l with tritium detected at all depths three mixing end members are identified 1 ca na cl shield brine 2 glacial meltwater recharged at the margin of the retreating laurentide ice sheet at 10 ka and 3 modern meteoric water mixing fractions calculated for inflows on five mine levels illustrate the infiltration of modern water along specific fault planes tritium data for the modern component are corrected for mixing with brine and glacial waters and interpreted with an exponential piston flow model results indicate that the mean transit time from surface to 1300 m depth is about 23 years in the early period after drift construction in 1979 but decreases to about 17 years in the past decade the persistence of glacial meltwater in the subsurface to the present time and the rapid circulation of modern meteoric water since the start of mining activities underline the importance of gradient in addition to permeability as a control on deep groundwater flow in the canadian shield q 2000 elsevier science b v all rights reserved

the extreme melt across the greenland ice sheet in 2012 1 the discovery of the 2012 extreme melt event across almost the entire surface of the greenland ice sheet is presented data from three different satellite sensors including the oceansat 2 scatterometer the moderate resolution imaging spectroradiometer and the special sensor microwave imager sounder are combined to obtain composite melt maps representing the most complete melt conditions detectable across the ice sheet satellite observations reveal that melt occurred at or near the surface of the greenland ice sheet across 98 6 of its entire extent on 12 july 2012 including the usually cold polar areas at high altitudes like summit in the dry snow facies of the ice sheet this melt event coincided with an anomalous ridge of warm air that became stagnant over greenland as seen in melt occurrences from multiple ice core records at summit reported in the published literature such a melt event is rare with the last significant one occurring in 1889 and the next previous one around seven centuries earlier in the medieval warm period given its rarity the 2012 extreme melt across greenland provides an exceptional opportunity for new studies in broad interdisciplinary geophysical research

classification seasonality and persistence of low frequency atmospheric circulation patterns abstract orthogonally rotated principle component analysis rpca of northern hemisphere 1 month mean 700 mb heights is used to identify and describe the seasonality and persistence of the major modes of interannual variability the analysis is detailed and comprehensive in that 1 a high resolution approximately equal area 358 point grid is used for the virtually maximum possible 35 year period of record 2 a positive bias in the nmc data base in the early 1950s in the subtropics is largely eliminated for the first time and 3 homogeneous separate analyses of each month of the year are carried out detailing the mouth to month changes in the dominant circulation patterns winter results are similar to those of other recent rpca and teleconnection studies except that some less obvious patterns are identified and further detail of the better known patterns is provided two north south dipole patterns are found over the pacific ocean west pacific oscillation and east pacific pattern and over the atla

analysis of the warmest arctic winter 2015 2016 december through february 2015 2016 defines the warmest winter season over the arctic in the observational record positive 2 m temperature anomalies were focused over regions of reduced sea ice cover in the kara and barents seas and southwestern alaska a third region is found over the ice covered central arctic ocean the period is marked by a strong synoptic pattern which produced melting temperatures in close proximity to the north pole in late december and anomalous high pressure near the taymyr peninsula atmospheric teleconnections from the atlantic contributed to warming over eurasian high latitude land surfaces and el nino related teleconnections explain warming over southwestern alaska and british columbia while warm anomalies over the central arctic are associated with physical processes including the presence of enhanced atmospheric water vapor and an increased downwelling longwave radiative flux preconditioning of sea ice conditions by warm temperatures affected the ensuing spring extent

stress and fluid driven failure during fracture array growth implications for coupled deformation and fluid flow in the crust brittle experimental deformation on dolomite rocks shows for the fi rst time the differ ence in growth of fracture networks by ordinary percolation and invasion percolation processes stress driven fracture growth in the absence of fl uid pressure is an ordinary percolation process characterized by distributed nucleation and growth of microfractures which coalesce with increasing strain to form a connected fracture network fluid pres sure driven fracture growth is more akin to an invasion percolation process characterized by preferential fracture growth occurring initially at the high fl uid pressure part of the rock with progressive deformation the network propagates rapidly through the sample and away from the high fl uid pressure reservoir x ray microtomography analysis suggests that the fracture network in three dimensions 3 d is probably a fully connected network at peak stress conditions whereas conventional 2 d analysis suggests that connectivity only occurs at shear failure the development of 3 d fracture connectivity prior to shear failure has important implications for fl uid fl ow and fl uid pressure changes immediately prior to rupture nucleation in active fault zones for fl uid migration in ore producing hydrothermal systems and for reservoir integrity in hydrocarbon systems

a sem cathodoluminescence study of quartz in mildly deformed granite from the region of the atotsugawa fault central japan abstract cathodoluminescence cl images of quartz in granite distributed around the atotsugawa fault in central japan were observed by scanning electron microscopy and compared to optical microscope observations of the same crystals narrow or wide dark bands or dots were commonly recognized in the cl images almost all dots or narrow bands correlate with isolated bubbles or semi planar bubble arrays along healed cracks respectively some wide bands correspond to cracks filled with other minerals chlorite calcite mica etc or can be distinguished as zones with an extinction differing from that of surrounding areas in quartz crushed zones composed of healed crack arrays other wide bands are healed cracks where quartz is precipitated in optical continuity the quartz cl images displayed overall textures composed of mineral filled cracks bubble arrays along healed cracks and crushed zones more clearly than normal optical images healed cracks containing quartz precipitated in optical continuity with the enclosing grains were distinctly revealed as dark bands in cl images the abundance of these minor deformation structures as revealed in cl images increases with proximity to the fault therefore cl textures of quartz are an important aid in examining brittle deformation textures and understanding the tectonic processes that produce them

a possible link between winter arctic sea ice decline and a collapse of the beaufort high a new study by moore et al 2018 this issue highlights a collapse of the anticyclonic beaufort high atmospheric circulation over the western arctic ocean in the winter of 2017 and an associated reversal of the sea ice drift through the southern beaufort sea eastward instead of the predominantly westward circulation the authors linked this to the loss of sea ice in the barents sea anomalous warming over the region and the intrusion of low pressure cyclones along the eastern arctic in this commentary we discuss the significance of this observation the challenges associated with understanding these possible linkages and some of the alternative hypotheses surrounding the impacts of winter arctic sea ice loss

japan sea opening history and mechanism a synthesis the respective tectonic effects of back arc spreading and continental collision in asia are considered either as two independent processes or as closely interrelated extrusion tectonics assumes that the opening of the south china sea and the left lateral motion along the red river fault are geometrically linked in a pull apart manner this model is not accepted by several workers because the structural link between the two processes is not clearly demonstrated in the case of the japan sea we can show without ambiguity that back arc opening was controlled by large intracontinental strike slip faults which can be easily understood as effects of the india asia collision far from the indenter the japan sea opened in the early miocene in a broad pull apart zone between two major dextral strike slip shear zones the first one extends from north sakhalin to central japan along 2000 km it has accommodated about 400 km of finite displacement deformation along it varies from dextral transpression in the north to dextral transtension in the south the second is between korea and sw japan and has accommodated a smaller displacement of about 200 km the extensional domain in between lies in the back arc region of japan distributed stretching of the arc crust resulted in the formation of most of the japan sea while localized oceanic spreading at the southern termination of the eastern transpressional shear zone shaped the japan basin the first oceanic crust was formed in a small triangle based on the eastern shear zone and spreading propagated westward inside the pull apart region timing of oceanic crust formation of formation of the dextral shear zones and of block rotation in between as well as the internal structure of the basins and the geometry of deformation along the master shear zones are used to reconstruct the opening history this evolution is discussed by comparison to other manifestations of the arc and back arc activity such as the history of sedimentation and volcanism the paper then suggests that the collision of india can have tectonic consequences as far north as japan and sakhalin and describes the geometrical relation of back arc opening there and diffuse extrusion

scandinavian pattern and its climatic impact a lasg institute of atmospheric physics chinese academy of sciences beijing china b department of earth and planetary science university of tokyo tokyo japan maintenance mechanisms of the scandinavian teleconnection pattern and its possible impact on the eurasian climate are investigated on the basis of long term monthly data its upstream portion over the north atlantic is forced and maintained by feedback forcing from transient eddies migrating along the nearby storm track with an additional contribution from incoming rossby wave activity from further upstream the primary anomaly centre over the scandinavian peninsula and the downstream portion of the pattern manifest themselves basically as rossby waves propagating towards central siberia and east asia under the modest feedback forcing from transient eddies the pattern shows apparent seasonality in its dynamical properties including the wave train orientation and wavelength under the seasonally varying transient eddy feedback forcing and waveguide structure for rossby waves in cold seasons the positive phase of the pattern causes cold air accumulation over a vast area extending from western siberia to the regions around lake baikal and lake balkhash while giving rise to decreased precipitation over northeastern europe western siberia and some of the arctic coastal regions the pattern also changes the north atlantic sea surface temperature differently between autumn and winter

a strong phase reversal of the arctic oscillation in midwinter 2015 2016 role of the stratospheric polar vortex and tropospheric blocking in january 2016 asia and north america experienced unusual cold temperatures although the global average of surface air temperature broke the warmest record during a strong el nino event this was closely related to the remarkable phase transition of the arctic oscillation ao which can be explained by stratosphere troposphere interactions first the quasi biennial oscillation changed to its westerly phase in summer 2015 and the stratospheric polar vortex was stronger in early to midwinter 2015 2016 as blocking did not occur in december the associated downward propagation signal resulted in a strongly positive ao in late december 2015 second after late december the positive phase of pacific north america pattern became apparent in el nino event which strengthened the aleutian anticyclone in the stratosphere in addition an equivalent barotropic blocking anticyclone was established in the troposphere over asia the coexistence of blocking over asia and north america characterized the negative ao and a strong zonal wave number 2 pattern due to stronger zonal wave number 2 signals from the troposphere the stronger stratospheric polar vortex was elongated with two cyclonic centers over asia and the north atlantic in january the resultant southward displacement of polar vortices was followed by rare snowfall in the subtropical region of east asia and a heavy snowstorm on the east coast of the united states

brittle tectonothermal evolution in the forsmark area central fennoscandian shield recorded by paragenesis orientation and 40ar 39ar geochronology of fracture minerals in this paper we show how studies of fracture mineral paragenesis their orientation and ar 40 ar 39 geochronology can be applied in order to recognise the brittle tectonothermal evolution in an area samples were selected from nearly 18 km of drill cores from the upper i km of the fennoscandian shield obtained during the site investigation for a repository of spent nuclear fuel in forsmark central sweden four major events of fracturing and or reactivation of fractures associated with fracture mineralisation have been distinguished the first event was characterised by precipitation of epidote quartz and chlorite along preferably sub horizontal and gently dipping fractures or steep wnw ese to nw se fractures precipitation occurred between 1 8 and 1 1 ga possibly during the late stage of the svecokarelian orogeny close to 1 8 1 7 ga the second event is associated with precipitation of hematite stained adularia and albite prehnite laumontite calcite and chlorite preferably along steep ene wsw to nne ssw and nnw sse fractures precipitation occurred around 1107 7 to 1034 3 ma probably due to effects from the sveconorwegian orogeny this event was followed by a period with dissolution of fracture minerals and subsequent precipitation of mainly calcite quartz pyrite and asphaltite during the palaeozoic the formation fluid emanated from an overlying organic rich sedimentary cover precipitation occurred during reactivation of proterozoic fractures but formation of new fractures is also inferred possibly due to far field effects of the caledonian orogeny or elevated hydrostatic pressure due to its foreland basin the latest event is dominated by clay minerals chlorite and calcite along hydraulically conductive fractures these minerals are prominent along sub horizontal and gently dipping fractures but also occur in sets of steeply dipping fractures it is inferred that the hydraulically conductive fractures are proterozoic structures in which mineral precipitation has occurred during a long period however some of the near surface sub horizontal fractures may be quaternary in age c 2009 elsevier b v all rights reserved less

grain boundary microcracking of granitic rocks from the northeastern region of the atotsugawa fault central japan sem backscattered electron images abstract backscattered electron bse images from granitic rocks gathered in and around the northeastern region of the atotsugawa fault in central japan were examined by scanning electron microscopy bse images reveal that grain boundary microcracking strongly depends upon the mineralogy of the two adjacent grains at grain boundaries there are six possible different mineral pairings of the three main constituent minerals quartz plagioclase and k feldspar found in granitic rocks each grain boundary can be separated into one of two types a partially to entirely open grain boundary or a closed grain boundary grain boundaries can be classified by their decreasing sense of openness 1 quartz feldspars plagioclase and k feldspars 2 quartz quartz 3 piagioclase plagioclase 4 k feldspar plagioclase and 5 k feldspar k feldspar boundaries microcracks in grain boundaries are commonly found in a wide zone offset of the shattered zone of the fault the number and types of partially to entirely open grain boundaries increase with proximity to the fault following the above sequence the number and types can be used to detail the special zoning of rock masses around a fault

faults and their associated host rock deformation part i structure of small faults in a quartz syenite body southern israel we analyze pervasive and discontinuous deformation associated with small faults in a quartz syenite body in southern israel the analysis includes detailed mapping measurement of in situ mechanical rock properties and microstructural study of the faults the mapped faults have 1 100 m long horizontal traces consisting of linked curved segments the segmented nature of the faults is also apparent at the 1 10 mm scale the observed deformation features are breccia as well as intra and inter granular fractures these features are accompanied by reduction of the young modulus and uniaxial strength of the host rock the deformation features are zoned from a central fault core through a damage zone to the protolith at distances of 0 05 0 06 the fault length shear strains up to 300 were calculated from measured marker lines displacements and distortion in proximity to the faults we argue here that the fault related deformation during fault propagation is manifested by highly localized deformation in a process zone having a width of 0 001 0 005 of the fault length fault related deformation due to subsequent slip along the existing faults is analyzed in part ii the observed self similarity of the discontinuities over five length orders of magnitude and the outstanding lack of tensile microcracks suggest fault initiation and growth as primary shear fractures q 2003 elsevier science ltd all rights reserved

the role of moist intrusions in winter arctic warming and sea ice decline abstractthis paper examines the trajectories followed by intense intrusions of moist air into the arctic polar region during autumn and winter and their impact on local temperature and sea ice concentration it is found that the vertical structure of the warming associated with moist intrusions is bottom amplified corresponding to a transition of local conditions from a cold clear state with a strong inversion to a warm opaque state with a weaker inversion in the marginal sea ice zone of the barents sea the passage of an intrusion also causes a retreat of the ice margin which persists for many days after the intrusion has passed the authors find that there is a positive trend in the number of intrusion events crossing 70 n during december and january that can explain roughly 45 of the surface air temperature and 30 of the sea ice concentration trends observed in the barents sea during the past two decades

particle size and energetics of gouge from earthquake rupture zones surprisingly considering the forces that we see at the surface not all the energy involved in an earthquake is transformed into ground motion much of it is consumed by frictional heating and rock pulverization an analysis of pulverized rock or gouge collected from the san andreas fault in california and from a rupture zone at 2 km depth in a south african gold mine contradicts the commonly held view that gouge surface energy is a negligible component of earthquake energy balance the analysis reveals unexpected diminutive particles in gouge samples indicating that pulverization not frictional heating is the major consumer of earthquake energy at depth this might explain the heat flow anomaly seen in the san andreas fault system and perhaps some other long standing puzzles in earthquake energetics grain size reduction and gouge formation are found to be ubiquitous in brittle faults at all scales1 2 3 4 and most slip along mature faults is observed to have been localized within gouge zones5 6 this fine grain gouge is thought to control earthquake instability3 6 7 8 and thus understanding its properties is central to an understanding of the earthquake process7 9 here we show that gouge from the san andreas fault california with 160 km slip and the rupture zone of a recent earthquake in a south african mine with only 0 4 m slip display similar characteristics in that ultrafine grains approach the nanometre scale gouge surface areas approach 80 m2 g 1 and grain size distribution is non fractal these observations challenge the common perception that gouge texture is fractal10 11 and that gouge surface energy is a negligible contributor to the earthquake energy budget3 9 12 we propose that the observed fine grain gouge is not related to quasi static cumulative slip but is instead formed by dynamic rock pulverization during the propagation of a single earthquake

strike slip fault terminations at seismogenic depths the structure and kinematics of the glacier lakes fault sierra nevada united states 1 structural complexity is common at the terminations of earthquake surface ruptures similar deformation may therefore be expected at the end zones of earthquake ruptures at depth the 8 2 km long glacier lakes fault glf in the sierra nevada is a left lateral strike slip fault with a maximum observed displacement of 125 m within the fault pseudotachylytes crosscut cataclasites showing that displacement on the glf was accommodated at least partly by seismic slip the western termination of the glf is defined by a gradual decrease in the displacement on the main fault accompanied by a 1 4 km wide zone of secondary faulting in the dilational quadrant of the glf the secondary faults splay counterclockwise from the main fault trace forming average angles of 39 with the main fault slip vectors defined by slickenlines plunge more steeply west for these splay faults than for the glf static stress transfer modeling shows that the orientations of the splays and the plunge of displacement on those splays are consistent with displacement on the main fault the glf termination structure shows that structural complexity is present at the terminations of faults at seismogenic depths and therefore ruptures that propagate beyond fault terminations or through step overs between two faults will likely interact with complex secondary fault structures models of dynamic rupture propagation must account for the effect of preexisting structures on the elastic properties of the host rock additionally aftershock distributions and focal mechanisms may be controlled by the geometry and kinematics of structures present at fault terminations

microfracture analysis of fault growth and wear processes punchbowl fault san andreas system california abstract fabric and timing relations of mode i microfractures are used to test current hypotheses for the origin of damage along large displacement faults by the processes of fault growth and wear oriented samples 0 075 m to 1 km from the punchbowl fault surface i e ultracataclasite layer document an increase in development of preferred orientation and increase in density of microfractures towards the ultracataclasite layer defining a zone of fault related microfracture damage about 100 m thick a distinct microfracture set that is perpendicular to the slip direction of the fault is present throughout the damage zone this implies that the average orientation of the maximum principal compressive stress within the damage zone was nearly normal to the fault surface two additional microfracture sets are present one oriented at low angles to the fault within meters of the ultracataclasite layer and another low angle set that occurs in the outermost damage zone the preferred orientations and timing relations are most consistent with local damage accumulation from stress cycling associated with slip on a geometrically irregular relatively weak fault surface low angle microfractures nearest the ultracataclasite layer also may record wear associated with the passage of earthquake ruptures and those in the outermost damage zone may be consistent with andersonian fault formation and subsequent fault weakening

microscopic features of quartz and clay particles from fault gouges and infilled fractures in granite discriminating between active and inactive faulting abstract to assist in identifying faults that have a significant potential for displacement at or near the ground surface we carried out in depth investigations on fault gouges and a fracture infilled with clay clay vein in the kojaku granite on the tsuruga peninsula central japan we sampled several fault gouges at different stages of evolutions and clay rich infilling of a fracture with no evidence of offset based on our field observations gouge in an active fault is characterized by 1 stacked layers of different colors made up of comminuted fragments and clays and 2 injection of the fragments and clays from the gouge into the surrounding rocks indicating an accumulation of seismic induced shearing our thin section observations and x ray diffraction analyses show that all our samples are similar in the degree of fragmentation and mineral composition and because of this our study became focused mainly on microscopic features using laser diffraction particle size analysis scanning electron microscopy sem and transmission electron microscopy tem we identified the mineralogical and textural characteristics of the samples in order to improve our ability to discriminate between active and inactive faulting particle size distribution analysis showed that the gouge in the active fault contains the greatest abundance of finer particles due to multiple slip events which contrasts with the clay rich infilling of a fracture sem examination of the quartz particles showed that the gouge in the active fault contains more particles that have retained sharp and smooth crystal surfaces formed by fracturing than do either the gouges in minor faults that show no evidence of recent shear or the clay rich infilling of a fracture in contrast tem observations of very fine clay minerals approximately

meteorological conditions in a thinner arctic sea ice regime from winter to summer during the norwegian young sea ice expedition n ice2015 atmospheric measurements were made over arctic sea ice north of svalbard from winter to early summer january june 2015 during the norwegian young sea ice n ice2015 expedition these measurements which are available publicly represent a comprehensive meteorological data set covering the seasonal transition in the arctic basin over the new thinner sea ice regime winter was characterized by a succession of storms that produced short lived less than 48 h temperature increases of 20 to 30 k at the surface these storms were driven by the hemispheric scale circulation pattern with a large meridional component of the polar jet stream steering north atlantic storms into the high arctic nonstorm periods during winter were characterized by strong surface temperature inversions due to strong radiative cooling radiatively clear state the strength and depth of these inversions were similar to those during the surface heat budget of the arctic ocean sheba campaign in contrast atmospheric profiles during the opaquely cloudy state were different to those from sheba due to differences in the synoptic conditions and location within the ice pack storm events observed during spring summer were the result of synoptic systems located in the barents sea and the arctic basin rather than passing directly over n ice2015 these synoptic systems were driven by a large scale circulation pattern typical of recent years with an arctic dipole pattern developing during june surface temperatures became near constant 0 c on 1 june marking the beginning of summer atmospheric profiles during the spring and early summer show persistent lifted temperature and moisture inversions that are indicative of clouds and cloud processes

quantitative description and analysis of earthquake induced deformation zones along strike slip and dip slip faults 1 deformation zones are belts of high strains that can occur at the ground surface centered or asymmetrical relative to the trace of an earthquake fault and can range in width from a meter or two up to hundreds of meters in order to minimize damage to engineering structures within deformation zones one needs to be able to determine the characteristics of the deformation zones we develop an elastic plastic model of fault slip propagation to explain formation of deformation zones and estimate certain parameters to characterize deformation zones our theory suggests the ratio of widths of deformation zones in hanging wall and footwall of dipping faults should be controlled by fault dip angle and the kind of fault the relations are different for strike slip and dip slip faults also the total width of the deformation zone normalized with fault slip during the earthquake should be determined by the dip angle the exponent of the yield condition and the kind of fault the theoretical parameters measured for deformation zones along the strike slip duzce bolu fault at kaynasli turkey and two deformation zones along the chi chi thrust fault taiwan agree well with parameters determined from geophysical and geological sources the theoretical model also indicates that the winnetka strain belts related to the 1994 northridge earthquake could have formed above a previously unknown blind fault at winnetka the analysis suggests that the winnetka fault is a normal dip slip fault dipping 54 s with a fault tip depth of 360 m

origin and mechanical significance of foliated cataclastic rocks in the cores of crustal scale faults examples from the median tectonic line japan 1 the median tectonic line mtl is japan s largest onshore fault and has been active since the mid cretaceous foliated cataclastic fault rocks are exceptionally well exposed in the fault core at anko nagano prefecture following an early phase of mylonitization and exhumation during left lateral shearing brittle fracture and cataclasis occurred leading to the development of centimeter to submillimeter spaced fault zone parallel fracture systems these fracture systems established an initial architectural hierarchy that influenced the subsequent development of foliated cataclasites and gouge initially fracture systems coalesced to form interconnected zones of fine grained ultracataclasite fluid influx at the onset of grain scale brittle deformation led to precipitation of fibrous chlorite within the ultracataclasites ultimately leading to the development of an interconnected network of foliated phyllosilicate rich cataclasites and gouges in the core of the mtl the brittle reduction of grain size and ingress of a chemically active fluid phase simultaneously promoted reaction softening and diffusive mass transfer in the foliated ultracataclasites leading to rate dependent frictional viscous flow at sub byerlee friction values associated weakening is indicated by the preferential localization of deformation within the ultracataclasites a protracted sequence of carbonate mineralization and cementation events is also recognized during the fault rock evolution and suggests episodic periods of fluid overpressuring a crustal scale fault zone model is proposed suggesting that the foliated cataclasites gouges are weak in the long term and represent shallower crustal equivalents of phyllonitic fault rocks exposed in more deeply exhumed fault zones including other parts of the mtl

recent extreme arctic temperatures are due to a split polar vortex abstractthere were extensive regions of arctic temperature extremes in january and february 2016 that continued into april for january the arctic wide averaged temperature anomaly was 2 0 c above the previous record of 3 0 c based on four reanalysis products midlatitude atmospheric circulation played a major role in producing such extreme temperatures extensive low geopotential heights at 700 hpa extended over the southeastern united states across the atlantic and well into the arctic low geopotential heights along the aleutian islands and a ridge along northwestern north america contributed southerly wind flow these two regions of low geopotential height were seen as a major split in the tropospheric polar vortex over the arctic warm air advection north of central eurasia reinforced the ridge that split the flow near the north pole winter 2015 and 2016 geopotential height fields represented an eastward shift in the longwave atmospheric circulation pattern compared to earlier in the decade 2010

opening mode of the japan sea inferred from the palaeomagnetism of the japan arc the western edge of the pacific plate is marked by a chain of back arc basins stretching from the aleutians through japan and the philippines to new zealand most of the basins lie behind volcanic island arcs far from continents and are the result of extension of the oceanic lithosphere1 but the japan sea is bounded on one side by continental crust the sikhote alin and korean peninsula of the asian continent and on the other by an active arc with continental fragments it can thus be said to be associated more with continental rifting1 4 than with oceanic processes we report here palaeomagnetic data from the japan arc which indicate that since the early miocene north east japan has rotated counter clockwise through 47 around a vertical axis while south west japan has rotated clockwise through 56 refs 5 8 we attribute this differential rotation which took place concurrently between 21 and 11 myr ago to the back arc opening of the japan sea8 with a double door mode that is there are two fan shaped spreading basins facing each other such a fan shaped opening is probably peculiar to the geological phenomenon of rifting of a continental fragment from thick continental lithosphere

textural evidence for recent co seismic circulation of fluids in the nojima fault zone awaji island japan abstract the hirabayashi borehole awaji island japan was drilled by the geological survey of japan gsj 1 year after the hyogo ken nanbu kobe earthquake 1995 mjma 7 2 this has enabled scientists to study the complete sequence of deformation across the active nojima fault from undeformed granodiorite to the fault core in the fault core different types of gouge and fractures have been observed and can be interpreted in terms of a complex history of faulting and fluid circulation above the fault core and within the hanging wall compacted cataclasites and gouge are cut by fractures which show high apparent porosity and are filled by 5 50 m euhedral and zoned siderite and ankerite crystals these carbonate filled fractures have been observed within a 5 5 m wide zone above the fault but are especially abundant in the vicinity 1 m of the fault the log normal crystal size distributions of the siderite and ankerite suggest that they originated by decaying rate nucleation accompanied by surface controlled growth in a fluid saturated with respect to these carbonates these carbonate filled fractures are interpreted as the result of co seismic hydraulic fracturing and upward circulation of fluids in the hanging wall of the fault with the fast nucleation of carbonates attributed to a sudden fluid or co2 partial pressure drop due to fracturing the fractures cut almost all visible structures at a thin section scale although in some places the original idiomorphic shape of carbonates is modified by a pressure solution mechanism or the carbonate filled fractures are cut and brecciated by very thin gouge zones these features are attributed to low and high strain rate mechanisms respectively the composition of the present day groundwater is at near equilibrium or slightly oversaturated with respect to the siderite calcite dolomite and rhodochrosite taken together this suggests that these fractures formed very late in the evolution of the fault zone and may be induced by co seismic hydraulic fracturing and circulation of a fluid with a similar composition to the present day groundwater they are therefore potentially related to recent earthquake activity

kinematic analysis of sinistral cataclastic shear zones along the northern margin of the mino belt central japan abstract in this paper cataclastic shear zones along the northern margin of the mino belt central japan are described and the significance of the shearing in the tectonic evolution of sw japan is examined the mino belt in sw japan is composed of accretionary complexes of jurassic to early cretaceous age field investigation revealed that remarkable cataclastic shear zones trending east to northeast run along the northern margin of the mino belt closely spaced cleavage is developed in these shear zones lineation on the cleavage plunges at shallow to moderate angles deformation structures e g composite planar fabric and asymmetric structure of clasts in the sheared rocks clearly indicate a sinistral sense of shear the shearing ceased by latest cretaceous time because the sheared rocks are overlain by unsheared upper cretaceous volcanic rocks the sinistral shearing may be closely related to cretaceous sinistral movement along the eastern margin of asia sinistral shearing along the northern margin of the mino belt can be considered as a key for re examining the tectonic development of sw japan

architectural evolution of the nojima fault and identification of the activated slip layer by kobe earthquake 1 evolutionary history of nojima fault zone is clarified by comprehensive examinations of petrological geophysical and geochemical characterizations on a fault zone in deep drilled core penetrating the nojima fault on the basis of the results we reconstruct a whole depth profile of the architecture of the nojima fault and identify the primal slip layer activated by 1995 kobe earthquake the deepest part 8 to 12 km depth of the fault zone is composed of thin slip layers of pseudotachylite 5 to 10 mm thick each 10 cm in total middle depth 4 to 8 km depth of the fault zone is composed of fault core 6 to 10 m thick surrounded by thick 100 m thick damage zone characterized by zeolite precipitation the shallow part of the fault zone 1 to 4 km depth is composed of distributed narrow shear zones which are characterized by combination of thin 0 5 cm thick each 10 cm in total ultracataclasite layers at the core of shear zones surrounded by thicker 1 to 3 m thick damage zones associated with carbonate precipitation an extremely thin ultracataclasite layer 7 mm thick activated by the 1995 kobe earthquake is clearly identified from numerous past slip layers overprinting one of the shear zones as evidenced by conspicuous geological and geophysical anomalies the nojima fault zone was 10 to 100 times thicker at middle depth than that of shallower and deeper depths the thickening would be explained as a combination of physical and chemical effects as follows 1 thickening of fault core at middle depth would be attributed to normal stress dependence on thickness of the shear zone and 2 an extreme thickening of damage zone in middle depth of the crust would result from the weakening of the fault zone due to super hydrostatic fluid pressure at middle depths the high fluid pressure would result from faster sealing with low temperature carbonate at the shallower fault zone

spatial distribution and characteristics of fracture zones near a long lived active fault a field based study for understanding changes in underground environment caused by long term fault activities abstract fracture zone development has a substantial impact on long term changes in the underground environment because fracture zones are potential major groundwater flowpaths as well as a locus for mechanical disturbance by fracturing to understand fracture zone development we surveyed the spatial distribution and characteristics of fracture zones in areas around the atotsugawa fault a long lived active fault in central japan within 500 m of the atotsugawa fault trace the number of exposed fracture zones increases sharply and most fracture zones greater than 2 m width are concentrated the width of the clay rich fault gouge in the majority of fracture zones is less than 1 m fracture zones greater than 2 m width along the atotsugawa fault are composed mainly of a zone with numerous fractures and breccia and are considered to act as a major conduit controlling regional groundwater flow based on rock features and deformation fabrics at meso and microscopic scales once fracture zones had formed epigenetic deformation was concentrated in the older fracture zones fracture zones formed by fracturing along hydrothermal veins or fracturing and weathering that accompanied displacement along joints schistosities or lithological boundaries are sparsely but widely distributed in the study area though most of their width are less than 2 m the existence of unfavorable hydraulic characteristics needs to be studied by engineered methods for the purpose of site selection and design of underground facilities

does enso force the pna abstract the primary effect of el nino southern oscillation enso sea surface temperature sst anomalies is to force distinct midlatitude patterns and not only to modify the probability of the internal variability patterns such as the pacific north american pna pattern of wallace and gutzler both the spatial structure and probability distribution of the external enso pattern are distinct from the pna pattern ensemble general circulation model gcm integrations for 30 winters have been analyzed in the pacific north america region these winters span the recent period of 1981 82 through 1998 99 plus 12 earlier winters the entire dataset includes six el nino warm and seven la nina cold events the ensemble size is nine simulations empirical orthogonal function eof analysis is carried out for all gcms and observed seasonal means for the gcm ensemble means and for the gcm deviations about the ensemble means eof 1 of the gcm 200 hpa height z ensemble mean agrees well with eof 1 of all gc

arctic lower tropospheric warm and cold extremes horizontal and vertical transport diabatic processes and linkage to synoptic circulation features abstractthe thermodynamic processes and synoptic circulation features driving lower tropospheric temperature extremes in the high arctic 80 n are investigated based on 10 day kinematic backward

thickness of the seismic slip zone this article reviews geologic and other evidence constraining the thickness of the principal slip zone psz that accommodates the bulk of coseismic shear displacement during an individual rupture event surface deformation from rupturing may occupy swaths tens of meters or more in width but trenches across active faults generally reveal that incremental slip is accommodated by a psz that is tens of centimeters or less in thickness geomorphic evidence coupled with the observations from trenching suggest a psz may stay well localized for distances of several kilometers through many rupture episodes mine exposures and exhumed fault zones demonstrate that pszs separating different lithologies within the fault core although contained within damage zones of variably fractured rock ranging up to hundreds of meters in thickness often comprise just a few centimeters of gouge ultracataclasite that have accommodated large finite displacements 1 km microstructural studies demonstrate incremental slip localized still further down to 1 10 mm as do other fault rock assemblages slickensides and slickenfibers fault veins of pseudotachylyte friction melt intravein septa in hydrothermal fault infills the accumulated evidence indicates that localization of coseismic shearing to less than 10 cm on planar faults is widespread throughout the crustal seismogenic zone with extreme localization to less than 1 cm not uncommon however some distributed coseismic shear may also develop especially at rupture irregularities coseismic reduction of shear resistance from friction melting t 1000 c or from transient thermal pressurization of aqueous fluids t 100 c requires slip during moderate to large earthquakes u 1 m to be restricted to narrow zones respectively a few centimeters or tens of centimeters in thickness given the evidence for slip localization the apparent scarcity of pseudotachylyte suggests either that seismic friction melting is a rare phenomenon or that pseudotachylyte is only rarely preserved in recognizable form within mature hydrated fault zones

3d thermobaric modelling of the gas hydrate stability zone onshore central spitsbergen arctic norway abstract dissociation of onshore natural gas hydrates nghs could lead to the release of methane directly to the atmosphere especially in arctic regions such as svalbard where enhanced climate warming has the capacity to promote rapid methane evasion to the atmosphere following the decay of permafrost and glacier ice here we present the first assessment of the ngh stability zone ghsz in central spitsbergen a climate sensitive part of svalbard where thermobaric conditions appear favourable for onshore ngh formation we developed an approach incorporating regionally constrained 3 dimensional parameterisation of temperature pressure and phase boundary 93 methane 7 ethane 35 ppt salinity to define the ghsz this resulted in an up to 650 m thick mean 308 m ghsz covering 74 8 of the study area thickening significantly in the east where the climate is colder perturbation of the base case parameters was undertaken to quantify the sensitivity of the ghsz to the variation in environmental conditions across the study area we present 26 examples of these deterministic scenarios and show that the largest changes in the ghsz were observed when either the ethane content to 20 or the regional pore water pressure to 125 hydrostatic were increased the ghsz also increased markedly when the geothermal gradient was reduced from 33 to 26 c km 1 but was almost completely inhibited by a dry gas 100 methane greater salinity 50 ppt or exposure to an increase in surface temperatures relative to the mean annual air temperature e g by 2 c most parameters affected both the upper and the lower stability boundary of the ghsz with the exception of the geothermal gradient which impacted primarily upon the latter given that svalbard is host to a proven petroleum system we conclude that nghs almost certainly exist onshore svalbard

jurassic dextral and cretaceous sinistral movements along the hida marginal belt abstract the hida marginal belt hmb which consists of various kinds of fault bound blocks is located between the continental massif of the hida belt and the mesozoic accretionary complex of the mino belt in central japan detailed field investigation reveals that the hmb had grown through the two different movements i e jurassic dextral and cretaceous sinistral movements the jurassic dextral ductile shear zones run in the southern marginal part of the hida belt and the northern part of the hmb whereas the cretaceous sinistral cataclastic shear zones occur in the southern part of the hmb and the northern marginal part of the mino belt geologic map and field evidence seem to suggest that the jurassic dextral movement form the fault bound blocks of the hmb to form the basic structure of the hida marginal belt i e formation of the proto hmb following the dextral movement the sinistral one restructured the proto hmb to complete the present feature of the hida marginal belt the cretaceous sinistral movement might result in the sinistral collision between the proto hmb and the mino belt

the atmospheric response to realistic arctic sea ice anomalies in an agcm during winter abstract the influence of realistic arctic sea ice anomalies on the atmosphere during winter is investigated with version 3 6 of the community climate model ccm3 6 model experiments are performed for the winters with the most 1982 83 and least 1995 96 arctic ice coverage during 1979 99 when ice concentration estimates were available from satellites the experiments consist of 50 member ensembles using large ensembles proved critical to distinguish the signal from noise the local response to ice anomalies over the subpolar seas of both the atlantic and pacific is robust and generally shallow with large upward surface heat fluxes 100 w m 2 near surface warming enhanced precipitation and below normal sea level pressure where sea ice receded and the reverse where the ice expanded the large scale response to reduced enhanced ice extent to the east west of greenland during 1982 83 resembles the negative phase of the arctic oscillation north atlantic oscillation ao nao with a ridge over t

structural and isotopic constraints on fluid flow regimes and fluid pathways during upper crustal deformation an example from the taemas area of the lachlan orogen se australia 1 structural and stable isotope studies of calcite veins and host rocks in a 1000 m thick devonian limestone sequence in the taemas area of the lachlan orogen in se australia indicate that externally derived fluids migrated through the sequence over a protracted interval during folding and associated reverse faulting at temperatures of 200 c the evolution of fluid pathways was governed by growth of fold related and fault related fracture networks at transiently supralithostatic fluid pressures the internal structures of veins indicate growth during repeated cycles of permeability enhancement and sealing systematic increase in 18o of vein calcite upward through the limestone sequence and the presence of an o isotope alteration front in the vein system is related to buffering of fluid compositions by fluid rock reaction during upward migration of overpressured low 18o fluids repeated switching of fractures between high permeability and low permeability states promoted episodic flow and changes in flow paths during progressive deformation a lack of significant migration of the isotopic front during the flow history is consistent with fluid rock interaction being associated with numerous separate pulses of fluid ascending through the percolation network irregular variations in fluid 18o with time during vein growth are interpreted to be driven by repeated changes in reactive path lengths reaction rates and flow rates in a discontinuous flow regime systematic upward changes in vein 18o over an area of 20 km2 requires that on a time averaged basis most of the vein system was hydraulically well connected to the external fluid reservoir and that growth of the fracture network occurred by fluid driven invasion percolation processes repeated failure and sealing events in the fracture system are interpreted to have been driven by episodic migration of fluid pressure waves up through the fracture network possibly in response to deeper level fault rupture events repeatedly breaching an overpressured fluid reservoir

the southern oscillation part i global associations with pressure and temperature in northern winter abstract we describe the global correlations between a measure of the southern oscillation and sea level pressure and surface air temperature in the northern winter the stability of these correlations were tested on the northern hemisphere for an 80 year period and it turned out that most stable correlation coefficients were found over india the north pacific ocean the rocky mountains and the central and western north atlantic ocean on the southern hemisphere most records are too short for a similar test but the following may tentatively be said about the southern oscillation in middle and high southern latitudes when pressure is low in lower latitudes over the south pacific ocean it tends to be high at higher latitudes of that ocean high over east antarctica and low in the belt of westerlies in the indian and south atlantic oceans in the zonal average on both hemispheres the pressure gradients in this extreme of the oscillation tend to be steeper at lower latitudes and flatter at higher latitud

identification of pathways for hydrogen gas migration in fault zones with a discontinuous heterogeneous permeability structure and the relationship to particle size distribution of fault materials previous studies have reported that high concentrations of h2 gas are released from active fault zones experimental studies suggest that the h2 gas is derived from the reaction of water with free radicals formed when silicate minerals are fractured at hypocenter depths during fault activities however the pathways for migration of deep seated fluids to surface are still unknown in this study we performed quick multipoint h2 gas measurements across a fault zone using a portable gas monitor and a hand drill the fault zone studied includes a smectite rich fault core dividing two clearly distinguishable damage zones granite cataclasite and welded tuff fault breccia the measurements show that h2 gas emissions collected in 2 3 h sampling periods from start of measurement range from 320 3 to 446 2 ppm min in the granite cataclasite and 60 5 to 137 8 ppm min in the welded tuff fault breccias negligible quantities of h2 gas could be collected from the fault core particle size distribution analyses of fault rocks indicate that the granite cataclasite tends to be rich in particles that are finer i e less cohesive and easy to disaggregate which leads to the inference that the granite cataclasite has high permeability based on the h2 gas measurements and the particle size distribution analyses the h2 gas is considered to have migrated in permeable damage zones mostly by advection with groundwater multipoint h2 gas measurement will be effective in qualitative delineation of variations in permeability of regional structures

numerical modelling of chloride propagation in the quaternary aquifer of the southern upper rhine graben the deep groundwater in the quaternary gravel sequence of the southern upper rhine graben locally contains high chloride concentrations near the river rhine between fessenheim france in the south and breisach germany in the north this historical pollution is mainly due to past infiltration from the former brine storage basins of the french potash mines on the fessenheim island and to a lesser extent from the leaching of the salt dumps of the german potash mines in buggingen and heitersheim the spreading of the salt plume was investigated by means of a groundwater model the aim of the model was to understand the brine movement the present distribution of chloride as defined by recent hydrochemical investigations and to select locations for new reconnaissance boreholes the geological structure was reproduced by a three layer model which was calibrated for steady state flow conditions the hydraulic conductivity of the first layer was determined by comparing measured and calculated heads in the model area the vertical resolution was refined to simulate the density dependent salt transport processes the transport of the salt plumes was simulated over a 40 year period starting at the beginning of brine storage in the 1950s the relevant transport parameters have been estimated in a sensitivity analysis where the simulated breakthrough curves of chloride concentration have been compared with the measured data the results of the groundwater model indicate that brines containing approximately 1 million tons of chloride are still present at the bottom of the aquifer these highly concentrated salt brines mix with fresh water from the upper part of the aquifer this dispersive process leads to the formation of a plume of chloride rich water extending downstream where pumping wells for several local water supplies are located