decadal variability in the kuroshio oyashio extension simulated in an eddy resolving ogcm abstract through analysis of a hindcast integration of an eddy resolving quasi global ocean general circulation model decadal variability in the kuroshio oyashio extension region is investigated with particular emphasis on that of the subarctic oyashio and the kuroshio extension ke fronts the ke front is deep and is accompanied by a sharp sea surface height ssh gradient with modest sea surface temperature sst gradient in contrast the subarctic front is shallow and is recognized as a zone of tight gradient in sst but not ssh as a decadal scale change from a warm period around 1970 to a cool period in the mid 1980s those fronts in the model migrate southward as observed and the associated pronounced cooling is confined mainly to those frontal zones reflecting the distinctive vertical structure of the fronts the mixed layer cooling is the strongest along the subarctic front whereas the subsurface cooling and the associated salinity changes are most pronounced along the ke front concomitan

experiments simulating surface deformation induced by pluton emplacement abstract we present centrifuge experiments to study the surface deformation induced by shallow pluton emplacement in a rheologically stratified crust sand simulates the topmost brittle crust plastilina and denser silicone represent more and less competent crustal portions respectively lighter silicone simulates a buoyant intrusion in the models density differences affect the rate of intrusion but not their evolution or shape whereas viscosity and strength stratifications control both the shape and rate of the intrusions with a higher viscosity contrast 10 2 4 between the intrusion and the embedding media the rise of the lighter silicone induces a laccolith like intrusion responsible for doming and thinning of the overburden an apical depression may form inducing silicone extrusion conversely with a lower 10 1 viscosity contrast the overburden and the intrusion exhibit a lens shaped form with a broad central depression bordered by an upward flexure towards the periphery a sag in the floor of the intrusion is commonly observed no silicone extrusion occurred the intrusion is a hybrid between a laccolith and a lopolith the comparison with nature 1 confirms roof uplift as an important means of accommodating space during pluton emplacement and 2 suggests that where roof uplift plays a major role pluton emplacement can induce a well correlated sequence of events at surface doming the development of a depression and extrusion

anatomy of north pacific decadal variability abstract a systematic analysis of north pacific decadal variability in a full physics coupled ocean atmosphere model is executed the model is an updated and improved version of the coupled model studied by latif and barnett evidence is sought for determining the details of the mechanism responsible for the enhanced variance of some variables at 20 30 yr timescales the possible mechanisms include a midlatitude gyre ocean atmosphere feedback loop stochastic forcing remote forcing or sampling error decadal variability in the model is expressed most prominently in anomalies of upper ocean streamfunction sea surface temperature sst and latent surface heat flux in the kuroshio oyashio extension koe region off japan the decadal signal off japan is initiated by changes in strength and position of the aleutian low the atmospheric perturbations excite sst anomalies in the central and eastern north pacific with opposing signs and canonical structure the atmospheric perturbations also change the ekm

multi taxa isotopic investigation of paleohydrology in the lower cretaceous cedar mountain formation eastern utah u s a deciphering effects of the nevadaplano plateau on regional climate we investigate the regional climatic effects of the formation of the nevadaplano plateau during the sevier orogeny in an overall warming world paleohydrology was reconstructed from 590 individual measurements of phosphate o isotopes in continental faunas of the lower cretaceous cedar mountain formation utah u s a semi aquatic turtles crocodiles and terrestrial dinosaurs taxa are compared to coeval pedogenic carbonates to interpret changing water sources over time samples were grouped into four stratigraphic faunas lower yellow cat upper yellow cat ruby ranch and mussentuchit members resulting isotopic values were converted to d18 ow values using established d 18 op d 18 ow and d 18 oc d 18 ow relationships at a formation scale turtles d 18 op 14 1 to 15 7 v smow and crocodiles d 18 op 15 0 to 19 2 document water compositions of 28 1 to 26 1 and 27 7 to 24 2 respectively within the zonal range for formation scale meteoric water at 34u n paleolatitude 27 1 to 24 8 established by pedogenic carbonates d18 oc 22 0 to 23 5 v smow these data suggest that like soil carbonates turtle and crocodile phosphate isotopes can be used as proxies for meteoric water isotopic composition dinosaurd18 op sauropods 19 7 to 21 9 ornithischians 16 6to 21 7 small theropods 16 9to 18 2 andlarge allosauroids 19 1 to 20 3 values generally exceed those of semi aquatic taxa using mass balance equations for modern terrestrial animals adjusted for size and inferred dinosaur physiology ingested water is calculated for the above dinosaur groups on a member scale when meteoric water values are compared with calculated dinosaur drinking water values are equal to or lighter than meteoric water for most herbivorous groups as low as 215 5 for ornithischians and equal to or heavier than meteoric water for most carnivorous groups as high as 22 0 for allosauroids changes in d18 ometeoric water d 18 odinosaur ingested water faunal assemblages and sedimentology from member to member correlate to thrusting events of the sevier orogeny high elevations in the orogeny attenuated the influences of pacific moisture causing rainshadow induced aridity on the leeward foreland basin during upper yellow cat time and hosted seasonal snow accumulation by the end of ruby ranch time as suggested by 18 o enriched water e g up to an average of 22 0 from an allosauroid tooth and extremely 18 o depleted water e g 215 5 for ornithischians in the ruby ranch member by mussentuchit time delivery of the western interior seaway dominated moisture to the region despite continued rise of the sevier mountains

centrifuge modelling of laccolith intrusion abstract laccolith intrusion has been investigated by centrifuge modelling silicone putty representing magma with bingham rheology is intruded by overburden pressure through a circular conduit into a stack of paraffin wax layers which represent sedimentary strata the model intrusions evolve through a sequence of geometric forms similar to those exhibited by natural laccoliths the results are also in accord with published mathematical analyses of laccolith formation the model magma first flows laterally between overburden layers to form a sill as the sill increases in area the cover strata are arched upwards into a sinusoidal bending form subsequently the overburden fails abruptly by kinking above the periphery of the intrusion and the form changes to a cupola separated from surrounding horizontal strata by a sharp inflection in the layering finally strata on the flanks of the cupola undergo a second episode of localized failure the top of the dome becomes flat and the dipping flanks become a monoclinal flexure surrounding this kink form a number of variables influence this evolution increased overburden strength thickness of overburden strata and total thickness of overburden all prolong the bending form to larger intrusion size delay the localized failure which marks the cupola and kink stages and reduce the aspect ratio of the intrusion at all stages effectively bonded overburden interfaces have a similar effect but interfaces with sharply defined yield strengths enhance development of the monoclinal flexure magmatic driving pressure affects the rate of intrusion but not the evolution of its form intrusion rate is also influenced by magma flow properties and probably by the form of the feeder conduit the range of final forms preserved by natural laccoliths probably results from competition between rate of intrusion controlled by driving pressure and conduit geometry and rate of chilling of magma in the laccoliths the model laccoliths form in times that scale to between one and a few tens of years in agreement with available estimates for natural laccoliths

flow and fabric development during the diapiric rise of magma scaled isothermal experiments of the internal circulation induced by viscous drag at a diapir country rock interface are compared with published theoretical studies of flow induced finite deformation inside a rising sphere and new numerical results are presented for the incremental strain pattern developed in spherical diapirs the results predict a time dependent deformation history within rising diapirs that produces finite strains characterized by strong oblate flattening strains at the margin and strong vertical prolate strains in the center with an intervening zone of low plane strain finite strains are discussed in terms of the different sub fabrics expected to form in granitoids after considering the history of rheology and temperature distribution in rising magma strong rheological and temperature gradients are predicted for the margins of internally circulating diapirs that can lead to the formation of strong penetrative foliations at the margin and magmatic or even isotropic fabrics in the i

temperature dependent rheology of bouncing putties used as rock analogs abstract experimental investigations have been carried out at the hans ramberg tectonic laboratory to determine the temperature dependent rheology of two bouncing or silicone putties commonly used for tectonic modelling namely rhodorsil gomme silbion and dow corning dilatant compound no 3179 using a capillary viscometer rheologic data are summarized in plots of stress pa versus shear strain rate s 1 rhodorsil gomme is generally newtonian and hence shows constant viscosity irrespective of strain rate and temperature its viscosity decreases by three orders of magnitude from 105 pa s to 102 pa s over the investigated temperature range 23 90 c by contrast dow corning dc3179 exhibits different flow regimes at different stress temperature combinations and the flow stress shows strong strain rate dependence within the same temperature range below 60 c dc3179 deforms above its yield strength with variable stress exponent of n 1 in the strain rate range 10 2 to 10 4 s 1 above 10 2 s 1 the power law exponent n of this material exhibits newtonian flow n 1 previous work has shown this behaviour of dc3179 at room temperature to be similar to that of a bingham plastic above 60 c this material deforms as a newtonian fluid and softens with increasing strain rate the viscosity of dc3179 spans three orders of magnitude from 106 pa s to 103 pa s for the same temperature range both materials show large variations of viscosity suggesting that they are thermally unstable i e they have large activation energies we applied the steady state creep equation a exp q rt n to characterize the flow behaviour of the silicone putties where the universal gas constant r 8 31 j k 1 mole 1 q is an activation energy for creep and a and n are constants the stress exponent n and the activation energy q for rhodorsil gomme remains nearly constant q 42 2 kj mole but for dc3179 the activation energy varies with temperature and stress at the investigated temperature range 23 90 c whereas the steady state creep equation can be used to characterize the flow behaviour of rhodorsil gomme it does not provide a good fit to the experimental data for dc3179 the activation energy for dc3179 varies with temperature and stress however for a restricted temperature range 60 90 c its activation energy q 82 3 kj mole also remains nearly constant as was also mentioned by previous investigators rhodorsil gomme is a suitable newtonian analogue for rock flow in nature dc3179 seems to be appropriate both as a newtonian and non newtonian rock analogue depending on temperature strain rate and power law exponent the implications of the test results to salt flow in nature are assessed

the control of overburden thickness on resurgent domes insights from analogue models abstract resurgent doming consists of the uplift usually accompanied by volcanic activity of part of a collapse caldera analogue models were used to investigate the architecture of resurgent domes dry sand simulates the brittle crust uprising silicone located at the base of the sand pack simulates magma the deformation pattern depends mainly upon 1 the ratio aspect ratio between the thickness of the sand overburden and the width of the silicone intrusion 2 the duration of experiment for aspect ratios 1 two concentric domes develop the first formed outer dome is bordered by inward dipping reverse ring faults while the inner dome by outward dipping normal ring faults the layers inside the dome are uniformly dipping for aspect ratios 0 4 the dome shows a crestal depression surrounded by radial fractures followed by an apical extrusion of silicone the internal structure of the dome is made up of domed layers independently from the aspect ratio the duration of the experiment enhances silicone extrusion a consistent structure is observed in most resurgent domes in nature the comparison between experiments and nature suggests that two distinct resurgence modes occur mainly depending on the aspect ratio thickness width of the crust overlying the magma chamber aspect ratios 1 develop a resurgent block with uniformly dipping layers and peripheral volcanic activity ischia and pantelleria type aspect ratios 0 4 develop a resurgent dome with a crestal depression domed layers within and peripheral and internal volcanic activity valles and long valley type

large scale variabilities of wintertime wind stress curl field in the north pacific and their relation to atmospheric teleconnection patterns 1 wintertime wind stress curl wsc field in the north pacific is investigated to reveal large scale variabilities and their relation to atmospheric teleconnection patterns it is found that the leading empirical orthogonal function eof and the next three rotated eof modes of wintertime wsc anomalies well correspond to those of atmospheric teleconnection patterns i e pacific north american pna western pacific wp tropical northern hemisphere tnh and eastern pacific ep teleconnection patterns respectively time coefficient of the first eof mode well correlates with the north pacific index and does with the pacific decadal oscillation index to some degree it is also found that sverdrup transports in the two zonal bands of 25 n 30 n and 42 5 n 47 5 n have highly negative correlation and these variations can be represented by the forcing field of the first eof mode the pna forcing makes both subtropical and subpolar gyres spin up spin down simultaneously

analogue models of laccolith formation abstract this paper describes dynamically scaled analogue models of laccolithic intrusions experiments consisted of the injection of a newtonian fluid low viscosity silicone putty into a sandpack with or without an interbedded ductile layer of silicone putty acting as a potential decollement level boundary conditions were chosen to analyze the influence of the thickness of the brittle cover and of the decollement layer on the pattern of intrusion further experiments were made to examine the effects of an extensional regime during intrusion experiments showed that 1 laccolith formation requires the occurrence of a decollement layer between two competent units 2 the critical thickness of the decollement layer necessary for laccolith formation decreases with increasing depth 3 laccoliths change from lenses to bell shaped with decreasing overburden 4 for a constant thickness of the decollement layer the largest diameter of laccoliths is proportional to the thickness of the overburden and 5 a syn injection gravitational sliding regime results in an asymmetric laccolith with amplification of the bell shape

transpressional shearing and strike slip partitioning in the late cretaceous sierra nevada magmatic arc california the rosy finch shear zone rfsz represents an example of synmagmatic strike slip tectonics in the east central sierra nevada and provides information on transpressional tectonics within magmatic arcs the rfsz 1 4 km wide and 80 km long is contained in late cretaceous granitoids 92 83 ma of the mono pass intrusive suite dextral strike slip deformation is indicated by a continuous band of orthogneiss mylonitic and cataclastic deformation characterized by subvertical foliations with subhorizontal lineations the style of dextral shearing in the rosy finch shear varies along strike from wide zones of ductile deformation in the youngest plutons to narrow zones of cataclastic deformation in the older plutons deformation of the youngest granitoids is synmagmatic as constrained by both field observations and isotopic studies dextral shearing occurs concurrently in contemporaneous intrusive suites to the north and south tuolumne and mount whitney suggesting strike slip movement along the axis of active plutonism field studies also suggest that contraction across the arc acted concurrently with strike slip movement consistent with a transpressional setting for the late cretaceous sierra nevada magmatic arc comparison of the field data with strain models of oblique plate convergence suggests that the rfsz is a preserved ductile signature of transcurrent motion of strike slip partitioning within a transpressional orogenic system recent plate reconstructions indicate a switch from sinistral to dextral oblique convergence at 95 ma which is consistent with the timing constraints on the dextral movement on the rfsz

climatology and decadal variations in multicore structure of the north pacific subtropical mode water the pycnostad of the north pacific subtropical mode water stmw often displays multiple vertical minima in the potential vorticity profile argo profile data from 2004 to 2015 are used to investigate inter annual to decadal variations of the multicore structure climatologically about 24 pycostads of stmw have multicore structure and most of them distribute in the region west of 150 e stmw cores are classified into three sub modes the cold middle and warm ones with potential temperatures of 16 0 17 c 17 18 c and 18 19 5 c respectively the kuroshio extension ke varies between stable and unstable states the unstable ke with large meanders increases the subsurface stratification and shoals the winter mixed layer east of 150 e with warmer temperatures there the dominant stmw type varies from the cold single type in stable ke years making up 72 of the profiles with stmw to the middle single one 53 in unstable years the variation of the dominant stmw type in the region east of 150 e subsequently affects the multicore structure of stmw west of 150 e in a broad region between 130 e and 180 e profiles with stmw are fewer in unstable years but the proportion of multicore profiles increases among stmw profiles this might be due to the split recirculation gyre with a chaotic ke

kuroshio extension variability and forcing of the pacific decadal oscillations responses and potential feedback abstract a forcing mechanism is sought for the large scale circulation changes in the kuroshio extension region of the western north pacific ocean as inferred by topex poseidon sea surface height ssh data the low frequency signal of the kuroshio extension over the last decade was characterized by a modulation in its zonal mean flow intensity the mean kuroshio extension jet weakened progressively from 1993 to 1996 and this trend reversed after 1997 the ability to simulate the major trends in the observed ssh signals with linear vorticity dynamics leads the authors to conclude that the modulation in the zonal mean jet was remotely forced by wind stress curl anomalies in the eastern north pacific ocean related to the pacific decadal oscillations pdos to be specific the weakening strengthening trend in 1993 96 1997 2001 was caused by westward expansions of negative positive ssh anomalies south of the kuroshio extension and positive negative ssh anomalies north of the kuroshio extension emerg

the emplacement of the granitic las tazas complex northern chile the relationship between local and regional strain abstract the coastal batholith of northern chile grew under transtensional extensional conditions that prevailed along the andean margin during the mesozoic the batholith hosts the atacama fault zone a major arc parallel fault system which was characterised by sinistral transtensional shearing during the early cretaceous the las tazas complex is a composite granitoid intrusion that was emplaced syntectonically along the atacama fault zone at 130 ma syntectonic emplacement is indicated by a consistent kinematic history between the complex and its wall rocks together with synchronous crystallisation and shearing ages in contrast to regional patterns the las tazas complex was emplaced during a local change from vertical east side down to dextral transcurrent displacement along the fault zone during intrusion strain was partitioned between non coaxial simple shearing within country rock mylonites and a flattening strain across the crystallising complex this combination indicates that the pluton was emplaced under temporary transpressive conditions that were localised around the pluton probably induced by magma emplacement such a difference between local and regional strain suggests that emplacement related structures should only be related to regional strain states with great care

long term variations of the kuroshio extension path in winter meridional movement and path state change abstractas an indicator of the kuroshio extension ke path the ke northern boundary kenb was detected based on the position of the strong winter sea surface temperature sst gradient between 142 and 155 e using high spatial resolution satellite derived sst for the 30 winters january to march from 1982 to 2011 the ke path showed meridional movement with a period of 10 15 yr and an amplitude of about 2 latitude the changes in latitudinal position of the ke path were initiated by a north south shift of the aleutian low al negative wind stress curl anomalies around 35 n in the eastern north pacific associated with a northward shift of the al induced a deepening of the main thermocline depth and then this deepening signal propagated westward reaching the ke region after about 3 yr where it caused the ke path to move northward the path state of the ke straight path convoluted path modulated on a time scale of 8 12 yr but this was not significantly correlated with the meridional movement of

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

variations of current path velocity and volume transport of the kuroshio in relation with the large meander abstract the variations of the kuroshio current path and their relations with current velocity volume transport and upstream position of the kuroshio are examined using sea level data after the long time non large meander nlm path during 1963 75 the kuroshio takes a large meander lm path during most of 1975 91 1975 80 1981 84 1986 88 and 1989 91 the study of these meanders confirms the description of the path of the kuroshio based on the three typical paths and the transitions between them with an exception being the 1981 84 lm path the formation and decay of the large meander are associated with velocity and position of the kuroshio in the tokara strait south of kyushu a small meander precursor of the large meander seems to be formed southeast of kyushu in relation with a temporary increase of kuroshio velocity and a northward shift of the kuroshio in the tokara strait an eastward propagation of the small meander leading to the lm formation is associated with remaining in the northe

dynamic models of continental rift valley systems abstract in experimental scale models simulating the major continental rift valley systems rifting is caused by diapiric uprise of viscous material induced by a centrifugal body force this force plays the same role as gravity in nature the scale models show that bending alone as a mechanism of rifting is unrealistic rather the rift structures form as a result of the combined effect of gentle bending and lateral stretching of the crust the models also show that graben structures could form at any stage of development of an ascending and laterally spreading diapiric body depending upon the density and viscosity contrast of the body and its surroundings and the strength of the model crust the close resemblance in structure of the models with natural rift systems suggests a close similarity of dynamics and driving forces

experimental studies of collapse calderas we present experiments to investigate the formation of calderas using inflatable balloons in a medium of fused alumina powder this system provides a model of a magma chamber in an homogeneous elastic media which scales to volcanic systems in terms of geometry and strength of the media three kinds of experiment were performed i the balloon was inflated and then deflated simulating pre emption tumescence and caldera collapse ii the balloon was deflated without prior inflation simulating caldera formation without pre eruption tumescence iii three balloons were inflated and deflated in a line simulating multiple magma chambers the influence of magma chamber shape was investigated using different shaped balloons balloon inflation formed a dome with a surface pattern of shallow polygonal fractures centrally and radial fractures peripherally uplift occurs along deep inward dipping concentric reverse faults deflation generated depressions with an outer set of concentric ring fractures surrounding a central funnel formed by sagging along numerous minor faults some of which formed during doming during collapse the concentric reverse faults were converted to normal faults and the radial normally faulted fractures were converted to reverse faults without prior tumescence an outer set of near vertical ring faults surround a flat central depression due to collapse of a coherent block an inner set of outward dipping reverse ring faults also develop the experimental caldera area increased with balloon size and increased as the balloon depth decreased for a given balloon volume and depth collapse area is significantly smaller if doming had occurred prior to collapse arcuate fractures can provide the pathways for magma ascent during pre emption tumescence smith bailey 1968 but the shallow radial and polygonal fracture systems may also influence vent location changes in fault geometry and sense of movement extension to compression and vice versa occur when subsidence initiates and can account for changes in vent location that occur in many eruptions multiple overlapping collapse calderas are associated with magma chamber migration whereas nested calderas can result from the activity of a single magma chamber

role of the gulf stream and kuroshio oyashio systems in large scale atmosphere ocean interaction a review abstract ocean atmosphere interaction over the northern hemisphere western boundary current wbc regions i e the gulf stream kuroshio oyashio and their extensions is reviewed with an emphasis on their role in basin scale climate variability sst anomalies exhibit considerable variance on interannual to decadal time scales in these regions low frequency sst variability is primarily driven by basin scale wind stress curl variability via the oceanic rossby wave adjustment of the gyre scale circulation that modulates the latitude and strength of the wbc related oceanic fronts rectification of the variability by mesoscale eddies reemergence of the anomalies from the preceding winter and tropical remote forcing also play important roles in driving and maintaining the low frequency variability in these regions in the gulf stream region interaction with the deep western boundary current also likely influences the low frequency variability surface heat fluxes damp the low frequency sst anomalies ove

experiments on cauldron formation a polygonal cauldron and ring fractures abstract the sequence of formation of the motojuku type cauldron fujita et al 1970 is summarized as follows 1 doming due to ascent of a magma body 2 development of normal faults which produce a polygonal cauldron and 3 eruption of acidic to intermediate pyroclastic material model experiments on a scale of 1 200 000 reveal that ascent of the magma body which was imitated by a ball of hardened putty produced a polygonal cauldron composed of radial and concentrically arranged short fractures on the roof of a dome no ring fractures were formed this type of cauldron develops near the surface on the other hand emission of magma which was imitated by evaporation of a ball of dry ice in brittle powdered material caused ring faults dipping outward and a circular cauldron without up or downwarping this type of cauldron develops upward from the magma body the former model is equated to the motojuku type cauldron and the latter model to the other types of cauldrons with ring fractures

crustal models of the geothermal areas of southern tuscany italy abstract geological and geophysical data gathered in the geothermal areas of southern tuscany located in the inner part of the northern apennines indicate the presence of granite intrusions the most relevant data are 1 regional asthenospheric ascent to a depth of 40 50 km 2 granitic dykes as old as 3 8 2 9 ma and a widespread contact aureole found in several deep geothermal wells 3 very high heat flow values interpreted as the result of convective circulation of hot fluids above shallow magmatic bodies 4 the presence of low density bodies inferred from low gravity values often correlated with positive heat flow anomalies 5 the occurrence of a highly reflective horizon named k in a depth range of 3 12 km in the geothermal areas as shown by seismic reflection data 6 a 30 40 km wide low velocity body below the k horizon whose existence is supported by local earthquake tomography and teleseismic studies 7 the presence of a conductive body which correlates well with the anomalous tomographic and teleseismic body as revealed by magnetotelluric surveys the goal of the paper is to test different alternative crustal models by using these data the models are 1 granite intrusion 2 geopressurized fluids below impervious layers 3 contact metamorphic aureole 4 mylonite layers at the upper lower crust transition and 5 some combination of the four the occurrence of shallow intrusive bodies still partially molten and associated with saline brines is considered the most tenable model

wind driven shifts in the latitude of the kuroshio oyashio extension and generation of sst anomalies on decadal timescales abstract the causes of decadal variations of north pacific sea surface temperatures ssts are examined using a hindcast performed with an ocean general circulation model thermodynamically coupled to an atmospheric mixed layer model ogcm aml model and forced by the time history of observed surface winds the shift in north pacific ocean climate that occurred around 1976 77 is focused on since this is the best observed example available after the 1976 77 shift the aleutian low deepened and moved to the southeast of its previous position this placed anomalous cyclonic flow over the north pacific the sst response as simulated by the ocean model consisted of two components a fast and local part and a delayed and remote part in the central pacific stronger westerlies cool the ocean by increased equatorward ekman drift here the dynamical cooling is sufficiently large that the surface fluxes damp the sst anomaly this ekman response is fast and local and cools the ssts beginning in 1977 and persistin

interannual modulations of oceanic imprints on the wintertime atmospheric boundary layer under the changing dynamical regimes of the kuroshio extension abstractthe kuroshio extension ke fluctuates between its different dynamic regimes on quasi decadal time scales in its stable unstable regime the ke jet is strengthened weakened and less more meandering the present study investigates wintertime mesoscale atmospheric structures modulated under the changing ke regimes as revealed in high resolution satellite data and data from a particular atmospheric reanalysis era interim in the unstable ke regime a positive anomaly in sea surface temperature sst to the north of the climatological ke jet accompanies positive anomalies in upward heat fluxes from the ocean surface wind convergence and cloudiness as revealed in the atmospheric reanalysis these positive anomalies coincide with local lowering of sea level pressure weaker vertical wind shear warming and thickening of the marine atmospheric boundary layer mabl anomalous ascent and convective precipitation in the stable ke regime by contrast the corresponding imprints of sharp sst

magma traps and driving pressure consequences for pluton shape and emplacement in an extensional regime abstract the level of emplacement and final form of felsic and mafic igneous rocks of the wichita mountains igneous province southwestern oklahoma u s a are discussed in light of magma driving pressure lithostatic load and crustal magma traps deposition of voluminous a type rhyolites upon an eroded gabbroic substrate formed a subhorizontal strength anisotropy that acted as a crustal magma trap for subsequent rising felsic and mafic magma intruded along this crustal magma trap are the a type sheet granites length thickness 100 1 of the wichita granite group of which the mount scott granite sheet is typical and smaller plutons of biotite bearing roosevelt gabbro in marked contrast to the subhorizontal granite sheets the gabbro plutons form more equant stocks with flat roofs and steep side walls late diabase dikes cross cut all other units but accompanying basaltic flows are extremely rare in the volcanic pile based on magmastatic calculations we draw the following conclusions concerning the level of emplacement and the shape of these intrusions 1 magma can rise to a depth at which the magma driving pressure becomes negligible magma that maintains a positive driving pressure at the surface has the potential to erupt 2 magma ascent may be arrested at a deeper level in the crust by a subhorizontal strength anisotropy i e crustal magma trap if the magma driving pressure is greater than or equal to the lithostatic load at the depth of the subhorizontal strength anisotropy 3 subhorizontal sheet intrusions form along crustal magma traps when the magma driving pressure greatly exceeds the lithostatic load under such conditions the magma driving pressure is sufficent to lift the overburden to create the necessary space for the intrusion 4 thicker steep sided stocks or batholiths with flat roofs form at crustal magma traps when the magma driving pressure approximates that of the lithostatic load under these conditions the necessary space for the intrusion must be created by other mechanisms e g stoping 5 subvertical sheets i e dikes form when the magma driving pressure is less than the lithostatic load at the level of emplacement

crustal scale en echelon p shear tensional bridges a possible solution to the batholithic room problem the apparent paradox of voluminous granitoid emplacement in an overall compressional magmatic are has been somewhat alleviated by the idea of pluton emplacement in tension cracks and dilational jogs within arc parallel strike slip fault systems as an alternative hypothesis we propose that an en echelon p shear array provides a continuous batholith scale zone of dilation along the trend of active magmatism and that it is favored by transpressional tectonics in the sierra nevada california the late cretaceous granitoids of the cathedral range intrusive epoch are consistent with emplacement into bridges between p shears because 1 they are elongated oblique to the magmatic trend consistent with p shear orientation within a dextral system 2 they were all emplaced within 5 10 m y along a 300 km trend resulting in a displacement rate of 1 cm yr across the arc and 3 syn to late magmatic dextral shear zones bound and crosscut the plutons as in a p shear tensional bridge

mechanics of active salt diapirism abstract an active diapir forcefully intrudes its overburden driven by diapir pressure that overcomes the resistance of the overburden strength possible causes for the driving pressure are differential loading of the source layer and a density contrast with the overburden possible resisting forces derive from the mass of the roof block and resistance to the faulting and folding that accommodate the intrusion for a typical density contrast between salt and a sedimentary overburden a simple force balance demonstrates that the diapir height must be more than two thirds to three quarters the thickness of the surrounding overburden to initiate substantial active diapirism narrow diapirs must be even taller physical and numerical modeling show that typical structures of active diapirism are a central crestal graben flanked by relatively unstrained flaps that rotate upward and outward curved reverse faults can separate the flaps from the regional overburden normal faults in the crestal graben propagate downward with new faults created farther outward as the roof arches over the rising diapir thin wide roofs develop multiple grabens separating a relatively flat roof from the rotating flaps in cases leading to emergence the piercing diapir evolves from a pointed crest to a progressively rounded and widening crest as the flaps rotate outward the numerical models show that overburden flexure contributes to early formation of active diapir structures but piercement does not continue to emergence unless the diapir is very wide or tall relative to the overburden thickness active diapirism becomes progressively more difficult for diapir crests ranging from a rectangle a round cornered rectangle a semicircle to a triangle with a pointed crest

internal strain within lava flows from analogue modelling internal strain within lava flows can be measured in the field from deformed bubbles or vesicle foliations preferred crystal orientation or ams studies these measurements have important implications for the determination of vertical velocity profiles and flow directions recent field studies show very contrasting strain patterns especially in vertical profiles an experimental study was conducted to relate variations in internal strain to different boundary conditions during flow results show that viscous flow in a straight channel along a basal slope produces three successive stretch trajectories in vertical flow planes these trajectories are related to the distribution with time of a simple shear component and a pure shear component viscous flow in a straight channel along a horizontal base reveals convex stretch trajectories in the vertical flow plane radial spreading at the mouth of a straight channel reveals concentric stretching perpendicular to the radial direction of displacement in the upper part of the flow strain components deduced from experiments may also explain fold formation during motion these experimental results provide a few end member strain patterns which may facilitate the interpretation of strain measurements in natural lava flows in terms of emplacement mechanisms

decadal variability of the kuroshio extension observations and an eddy resolving model hindcast abstract low frequency variability of the kuroshio extension ke is studied using observations and a multidecadal 1950 2003 hindcast by a high resolution 0 1 eddy resolving global ocean general circulation model for the earth simulator ofes in both the ofes hindcast and satellite altimeter observations low frequency sea surface height ssh variability in the north pacific is high near the ke front an empirical orthogonal function eof analysis indicates that much of the ssh variability in the western north pacific east of japan is explained by two modes with meridional structures tightly trapped along the ke front the first mode represents a southward shift and to a lesser degree an acceleration of the ke jet associated with the 1976 77 shift in basin scale winds the second mode reflects quasi decadal variations in the intensity of the ke jet both the spatial structure and time series of these modes derived from the hindcast are in close agreement with observations a linear rossby wave

influence of the meridional shifts of the kuroshio and the oyashio extensions on the atmospheric circulation abstract the meridional shifts of the oyashio extension oe and of the kuroshio extension ke as derived from high resolution monthly sea surface temperature sst anomalies in 1982 2008 and historical temperature profiles in 1979 2007 respectively are shown based on lagged regression analysis to significantly influence the large scale atmospheric circulation the signals are independent from the enso teleconnections which were removed by seasonally varying asymmetric regression onto the first three principal components of the tropical pacific sst anomalies the response to the meridional shifts of the oe front is equivalent barotropic and broadly resembles the north pacific oscillation western pacific pattern in a positive phase for a northward frontal displacement the response may reach 35 m at 250 hpa for a typical oe shift a strong sensitivity since the associated sst anomaly is 0 5 k however the amplitude but not the pattern or statistical significance strongly depends on the lag and an

variability of the kuroshio extension jet recirculation gyre and mesoscale eddies on decadal time scales abstract twelve years of sea surface height ssh data from multiple satellite altimeters are used to investigate the low frequency changes and the interconnections of the kuroshio extension ke jet its southern recirculation gyre and their mesoscale eddy field the dominant signal is characterized by the steady weakening of the ke jet recirculation gyre from 1993 to 1996 followed by a gradual strengthening after 1997 during the weakening period of 1993 96 the ke path migrated southward in general and this path migration reversed in direction during the strengthening period of the ke jet and recirculation gyre after 1997 by hindcasting the ssh signals using linear vorticity dynamics it was found that weakening strengthening in the ke jet and recirculation gyre is consistent with westward propagation of negative positive ssh anomalies generating in the eastern north pacific and strengthening during their westward propagation when the ke jet and recirculation gyre were in a weak mode during 19

separation of climatological imprints of the kuroshio extension and oyashio fronts on the wintertime atmospheric boundary layer their sensitivity to sst resolution prescribed for atmospheric reanalysis abstractmesoscale structures of the wintertime marine atmospheric boundary layer mabl as climatological imprints of oceanic fronts within the kuroshio oyashio extension koe region east of japan are investigated by taking advantage of high horizontal resolution of the era interim global atmospheric reanalysis data for which the resolution of sea surface temperature sst data has been improved these imprints including locally enhanced sensible and latent heat fluxes and local maxima in cloudiness and precipitation in association with locally strengthened surface wind convergence in the vicinities of sst fronts along the warm kuroshio extension and cool oyashio to its north are also identified in high resolution satellite data in addition to these mesoscale mabl features meridionally confined near surface baroclinic zones and zonally oriented sea level pressure slp minima associated with the dual sst fronts are represented in era interim only in the period of high resolution sst but those impri

response of rapidly developing extratropical cyclones to sea surface temperature variations over the western kuroshio oyashio confluence region the dynamical response of rapidly developing extratropical cyclones to sea surface temperature sst variations over the western kuroshio oyashio confluence wkoc region was examined by using regional cloud resolving simulations this study specifically highlights an explosive cyclone that occurred in early february 2014 and includes a real sst experiment cntl run and two sensitivity experiments with warm and cool sst anomalies over the wkoc region warm and cool runs the results derived from the cntl run indicated that moisture supply from the ocean was enhanced when the dry air associated with the cold conveyor belt ccb overlapped with warm currents further the evaporated moisture contributed substantially to latent heat release over the bent back front with the aid of the ccb leading to cyclone intensification and strengthening of the asymmetric structure around the cyclone s center such successive processes were more active in the warm run than in the cool run the dominance of the zonally asymmetric structure resulted in a difference in sea level pressure around the bent back front between the two runs the wkoc sst variations have the potential to affect strong wind distributions along the ccb through modification of the cyclone s inner system additional experiments with two other cyclones showed that the cyclone response to the wkoc sst variations became evident when the ccb north of the cyclone s center overlapped with that region confirming that the dry nature of the ccb plays an important role in latent heat release by allowing for larger moisture supply from the ocean

emplacement kinematics of a granite diapir the chindamora batholith zimbabwe the geometric features of a large 50 40 km granitic batholith and its surrounding greenstone belt envelope are described the batholith is made up of several intrusive components and an intrusion sequence based on contact relations and xenoliths has been established the igneous rocks show a local foliation s fabric and preferred orientation of minerals the intensity of this fabric accords with the finite strain determined from xenolith shape analysis when the strain variations are analysed in detail it appears that the batholith was built up by a succession of magmatic pulses each of which led to a stretching of the previously consolidated igneous material so called balloon tectonics evidence is presented that xenolith deformation commences only when the surrounding igneous material has crystallized and a method is suggested whereby the position of the surface separating crystal supported phase plastic behaviour from melt supported phase liquid behaviour at different stages in the plutonic history can be determined ductile shear zones are present and their geometry accords well with the shape changes necessary to allow the outer parts of the pluton to stretch

granite magma generation ascent and emplacement within a transpressional orogen crustal thickening during transpressive orogenesis may produce anatectic granites which may then localize deformation leading to transcurrent movement granites may be transported from sites of generation through the mid crust in dyke like channelways within relatively narrow strike slip shear zones which link to major fault zones in the upper crust extensional jogs within fault systems provide developing sites for the assembly of plutons from magma arriving from below the model is based upon observations from the cadomian belt of nw france which exposes sections through middle and upper levels of the late precambrian crust within different elements of the orogen the mechanism provides a favourable alternative to diapirism and explains the common collocation of granites and shear zone fault systems within orogenic belts

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

plutonism oblique subduction and continental growth an example from the mesozoic of california major episodes of mesozoic plutonism in california correlate with periods of oblique subduction and trench parallel transport of western california along intrabatholithic faults major episodes of plutonism occurred in the late jurassic during left oblique convergence and in the mid cretaceous during right oblique convergence in contrast a conspicuous lull in plutonism but continuation of volcanism in the earliest cretaceous coincides with a time when the north america farallon convergence vector although large in magnitude was oriented perpendicular to the trench this correlation suggests that plutonism is facilitated by strike slip faulting within the batholithic belt one explanation which helps to solve the plutonic room problem is that plutons are passively emplaced at releasing bends in the strike slip faults and volume is conserved by thrusting at the trench if this correlation is generally applicable then it implies that mid crustal plutonism is limited beneath areas in which the convergence vector is subperpendicular to the trench continental growth in such areas may occur dominantly by volcanism

eddy mean flow interaction in the decadally modulating kuroshio extension system abstract satellite altimeter sea surface height ssh data of the past 16 years are used to investigate the decadal changes of the kuroshio extension ke system that oscillated between a stable and an unstable dynamic state during the stable state of 10 1992 06 1995 and 01 2002 12 2004 the ke jet was intense and had a northerly zonal mean path and a well defined southern recirculation gyre during the unstable state of 07 1995 12 2001 and 01 2005 present the ke jet had a reduced eastward transport and a more southerly flow path transitions between the two dynamic states are caused by the basin scale wind stress curl forcing in the eastern north pacific related to the pacific decadal oscillations pdos or the north pacific gyre oscillations npgos during the positive pdo or negative npgo phase the intensified aleutian low generates negative ssh anomalies in the eastern north pacific through ekman divergence as these wind induced negative ssh anomalies propagate to the west as baroclinic rossby waves they weaken the zonal ke jet and shift its path southward as its path is pushed southward 32 n the deep reaching ke jet has to ride over the shallow shatsky rise generating localized disturbances that lead to their subsequent development along the ke jet west of the shatsky rise the sequence opposite to that listed above occurs when the pdo npgo changes to its negative positive phase after the ke system transitions from a stable to unstable state the enhanced eddy interaction is found to strengthen both the southern recirculation gyre and quasi stationary meanders along the ke s upstream path this nonlinear eddy interaction is important in determining the amplitude of the observed decadal ke variability

a role of eddies in formation and transport of north pacific subtropical mode water 1 hydrographic data acquired during 2001 by argo profiling floats deployed in the kuroshio recirculation region are used to verify the inference that mesoscale eddies prevailing in the recirculation region play an important role in the formation and transport of north pacific subtropical mode water npstmw that is the deeper winter mixed layer is formed preferentially where the thermocline is deeper in association with anticyclonic eddies in the succeeding seasons mesoscale eddies retain npstmw during their southwestward movement from the npstmw formation region so that anticylonic eddies contribute substantially to the npstmw transportation the spatial distributions of the mixed layer depth in winter and the npstmw thickness in the succeeding seasons based on the float data suggest that they are affected by mesoscale eddies the float data also provide the statistical relations of these quantities against the thermocline depth which are consistent with our inference

evidence for a wind driven intensification of the kuroshio current extension from the 1970s to the 1980s the spatial and temporal characteristics of oceanic thermal variations in the mixed layer and main thermocline of the midlatitude north pacific are distinctive suggesting different physical origins within the main thermocline 400 m depth the variability is dominated by a westward intensified pattern of decadal scale indicative of enhanced eastward geostrophic flow along the southern flank of the kuroshio current extension during the 1980s relative to the 1970s the authors argue that the decadal scale change in the strength of the kuroshio extension was a result of the dynamical adjustment of the oceanic circulation to a decadal variation in wind stress curl according to sverdrup theory four times daily wind stress fields from the national center for atmospheric research national centers for environmental prediction reanalysis project are used to compute the decadal change in sverdrup transport associated with the 1976 77 climate transition it is shown that the decadal changes in sverdrup transport inferred from the wind stress curl field and in observed geostrophic flow inferred from the upper ocean thermal field are consistent both in terms of spatial pattern and magnitude the decadal change in depth averaged geostrophic transport along the kuroshio extension referenced to 1 km is 11 6 sv similar to the sverdrup transport change 11 5 13 9 sv the decadal scale thermocline variation along the western boundary between 308 and 408n exhibits a lag of approximately 4 5 yr relative to the decadal variation in the basin wide wind stress curl pattern this delay may be indicative of the transient adjustment of the gyre scale circulation to a change in wind stress curl via long baroclinic rossby waves

measurements of friction coefficients and cohesion for faulting and fault reactivation in laboratory models using sand and sand mixtures abstract simple laboratory tests have been made on dry quartz sand and on mixtures of sand and clay and sand and cement tests were made on both low and high density specimens of each mixture as determined by physical handling techniques the tests included measurements of density estimates of the coefficient of internal friction based on fault orientation and estimates of the friction coefficients and cohesion values for fault initiation and reactivation in a shear frame apparatus which was also used to test artificial fault zones made from pure clay glass microspheres and wheat flour the results suggest that density is determined more by handling technique than by composition and that friction coefficients and perhaps cohesion both increase with increasing density the shear testing revealed a consistent drop in cohesion for fault reactivation in all densely packed mixtures tested although small this drop may be significant for some types of laboratory models

characteristics of mesoscale eddies in the kuroshio oyashio extension region detected from the distribution of the sea surface height anomaly abstract this study investigates the distribution of the sea surface height anomaly ssha with the aim of quantifying the characteristics of mesoscale eddies in the kuroshio oyashio extension region koer where intense mesoscale eddies are commonly observed during hydrographic surveys dense distributions of both anticyclonic eddies aes and cyclonic eddies ces are detected for the first time in koer with sufficient temporal and spatial coverage using the okubo weiss parameter without smoothing their contribution to the total ssha variance is estimated to be about 50 the zones of highest amplitudes are located north and south of the axis of the kuroshio extension ke for aes and ces which represent warm core and cold core rings respectively the areas extend poleward along the japan and kuril kamchatka trenches especially for aes eddies of both polarities and with moderate amplitudes are also recognized along the subarctic front saf eddies in areas north and south of the ke generally pro

north pacific gyre oscillation synchronizes climate fluctuations in the eastern and western boundary systems abstract recent studies have identified the north pacific gyre oscillation npgo as a mode of climate variability that is linked to previously unexplained fluctuations of salinity nutrient and chlorophyll in the northeast pacific the npgo reflects changes in strength of the central and eastern branches of the subtropical gyre and is driven by the atmosphere through the north pacific oscillation npo the second dominant mode of sea level pressure variability in the north pacific it is shown that rossby wave dynamics excited by the npo propagate the npgo signature in the sea surface height ssh field from the central north pacific into the kuroshio oyashio extension koe and trigger changes in the strength of the koe with a lag of 2 3 yr this suggests that the npgo index can be used to track changes in the entire northern branch of the north pacific subtropical gyre these results also provide a physical mechanism to explain coherent decadal climate variations and ecosystem changes between the no

quasi decadal variation in intensity of the western part of the winter subarctic sst front in the western north pacific the influence of kuroshio extension path state abstractvariations of the subarctic front saf which is extracted as a strong sea surface temperature sst gradient in the longitudinal band of 146 152 e were investigated over 30 winters january march from 1982 to 2011 using high spatial resolution satellite derived sst dataset and hydrographic observations the saf had little meridional movement in this longitudinal band lying between 40 and 41 n throughout the analysis period the saf intensity had a dominant quasi decadal time scale about 8 yr its intensity in the strong phase was up to about 50 higher than in the weak phase the saf intensity strongly reflected upper ocean conditions in the kuroshio oyashio confluence koc region just south of the saf in the strong saf phase large positive anomalies in both temperature and salinity were found in the koc region not only at the sea surface but also below 300 m and the water properties in the koc region were those of the kuroshio water the warm salty water in the koc region was supp

north pacific decadal variability in the community climate system model version 2 abstract north pacific decadal oceanic and atmospheric variability is examined from a 650 yr control integration of the community climate system model version 2 the dominant pattern of winter sea surface temperature sst variability is similar to the observed pacific decadal oscillation with maximum amplitude along the kuroshio extension sst anomalies in this region exhibit significant spectral peaks at approximately 16 and 40 yr lateral geostrophic heat flux divergence caused by a meridional shift of the kuroshio extension forced by basin scale wind stress curl anomalies 3 5 yr earlier is responsible for the decadal sst variability local surface heat flux and ekman heat flux divergence act as a damping and positive feedback respectively a simple linear rossby wave model is invoked to explicitly demonstrate the link between the wind stress curl forcing and decadal variability in the kuroshio extension the rossby wave model not only successfully reproduces the two decadal spectral peaks but a

re examining pluton emplacement processes abstract previous pluton emplacement studies have attempted to explain how space is made during pluton emplacement in fact the only means of making space during emplacement of mantle derived magmas in the crust are 1 lowering the moho or 2 outward displacement of the earth s surface other pluton emplacement mechanisms are material transfer processes mtps that do not increase the volume of the crust one frequently cited mtp for emplacement of concentrically zoned and ballooning plutons is ductile flow of wall rocks around the plutons the expected structures and total strains near such plutons are dependent on the three dimensional pluton shape the width of the deforming aureole whether the pluton is a piercing or non piercing diapir and in the latter case the number of body radii the pluton travels we have re examined a few such plutons and calculated the amount of material transfer caused by ductile flow in no case is more than 40 and in most cases only 15 35 of the required material transfer accommodated by wall rock flow the contact aureoles around these plutons are too narrow and or strains too low indicating that the plutons are predominantly discordant bodies with narrow 0 1 0 4 pluton radii concordant aureoles a comparison of strains in natural contact aureoles and those made in mechanical models of diapirs indicates that natural strains are at least an order of magnitude less than model strains we suggest that the similarities between models of diapiric ascent of spherical bodies and concentrically zoned plutons are superficial because the models are too simplistic instead we argue that the ascent and emplacement of magmas require multiple near field and far field mtps these mtps will show gradients with depth distance from the magma and with time rates of near field mtps must be rapid whereas far field rates are probably nearer to long term average rates of orogenic processes

decadal variation in winter mixed layer depth south of the kuroshio extension and its influence on winter mixed layer temperature abstractthe long term behavior of the wintertime mixed layer depth mld and mixed layer temperature mlt are investigated in a region south of the kuroshio extension ke 30 37 n 141 155 e an area of the north pacific subtropical gyre where the deepest mld occurs using historical temperature profiles of 1968 2014 both the mld and mlt in march have low frequency variations which show significant decadal 10 yr variations after the late 1980s observational data and simulation outputs from a one dimensional turbulent closure model reveal that surface cooling is the main control on winter mld in the late 1970s and 1980s whereas there is a change in the strength of subsurface stratification is the main control after 1990 in the latter period a weak strong subsurface stratification is caused by a straight path convoluted path of the ke and by a deepening shallowing of the main thermocline depth due to oceanic rossby waves formed as a result of positive negative anomalies of wind stress

physical modelling of overburden deformation around salt diapirs abstract salt diapirs produce highly complex deformation patterns in the surrounding overburden which are difficult to image seismically or model numerically to further the understanding of deformation around salt structures we have used physical models with brittle granular overburdens and simulated sedimentation accompanying diapiric rise rigid linear indentors produce a crestal horst above the indentor with two flanking graben large amounts of indentation produce predominantly reverse faults along the margins of the diapir and extensional faults over the crest in contrast hemispherical indentors produced inward dipping concentric reverse faults forefully intruded polymer diapirs produce a narrow crestal graben above the diapir crest downbuilt polymer diapirs produce extensional faults on the flanks of the diapirs which offset the diapir walls no clear secondary rim synclines were developed as polymer is withdrawn evenly from the whole of the polymer layer across the model strong and anisotropic layered overburden were simulated using cohesive clay and mica respectively detachments were formed along mica layers which suppressed faults with large throws cohesive layer deformation began with tensile fractures permitting rotation of fractured rafts around the sides of the diapir these progressively slip off the crest and create large gaps in the stratigraphy

interference between pluton expansion and non coaxial tectonic deformation three dimensional computer model and field implications abstract structures in orogenic belts are greatly controlled by interactions between pluton related and tectonic related strain fields however many aspects of the geometry and evolution of these structures are poorly known for example 1 what is the geometry of these structures if regional deformation is coaxial 2 how does this geometry change with progressive deformation this paper describes a three dimensional simulation of strain shape and magnitude as well as foliation and lineation patterns formed by interactions between pluton expansion and homogeneous coaxial deformation this simulation suggests that interactions between pluton expansion and regional uniaxial shortening generate patterns that are distinct from the patterns produced by regional uniaxial extension or regional non coaxial deformation for example shortening produces doughnut shaped constrictional rings about the pluton whereas extension produces apple shaped flattening regions around the pluton in addition shortening produces one continuous doughnut shaped low strain region around the pluton on the other hand extension creates two separate ellipsoidal low strain regions at the ends of the pluton furthermore shortening forms foliation rings that have triangular two dimensional sections and lineation is concentric around the axis of maximum shortening in contrast extension produces two separate foliation and lineation cones at the ends of the pluton all these structural and strain elements migrate away from the pluton with increasing expansion rates and towards the pluton with increasing tectonic deformation rates although structural studies around plutons should always integrate microstructural radiometric and field measurements simulation generated patterns can be used to evaluate 1 origin geometry and evolution of structures around plutons 2 mechanisms that explain inclusion trails within porphyroblasts 3 contribution of pluton related strains to strains measured in the country rock and 4 type and three dimensional orientation of regional kinematic schemes

fracture controlled magma conduits in an obliquely convergent continental magmatic arc magnetic fabric patterns of two mid cretaceous nested plutons 102 1 and 96 3 ma in the central sierra nevada batholith provide evidence that felsic magma emplacement and ascent occurred via north trending steeply dipping planar fracture conduits oriented obliquely to the arc u pb geochronology data indicate that emplacement of the plutons was separated by 2 to 10 m y and that they were emplaced in part via the same conduit magnetic fabrics in the younger pluton are related to its final emplacement which was strongly influenced by a system of host rock joints formation of the north trending conduits at 100 ma can be related to a small arc parallel dextral shear component that produced tension fractures and that was associated with high angle oblique convergence by 90 ma convergence had become sufficiently oblique for the development of nearly arc parallel structures which were then favored as magma conduits