role of the ocean in the decadal climate change in the north pacific 1 i have investigated features of decadal climate variability in the north pacific and clarified the role of the ocean in controlling them by analyzing historical data sets and executing experiments with a low order model detailed investigation of the variability of the wintertime aleutian low and water temperature in the subarctic frontal region implies a new scenario for the mechanism of the decadal variability the decadal variability can be interpreted as the transition process between two stable states cold and warm period in midlatitude atmosphere when the transition to a cold period occurs sea surface temperature in the subarctic frontal region begins to be lowered not only through the surface processes but by westward propagation of cold anomaly from eastern subarctic region as a baroclinic rossby wave as a result the meridional gradient of sea surface heat flux yq0 decreases its magnitude and then the forcing of the aleutian low is weakened when this weakening exceeds a threshold the transition from a cold to a warm period occurs abruptly after the transition to a warm period yq0 in turn increases its magnitude through the opposite processes to cause the reverse transition the timescale of this cycle is mainly determined by the propagation speed of a baroclinic rossby wave the el nino and southern oscillation variability both in the atmosphere and ocean can also affect the timescale by causing the thresholds for transitions to be temporarily exceeded experiments with a four variable low order model support the proposed mechanism of the decadal variability

tertiary tectonics of the border ranges fault system chugach mountains alaska deformation and uplift in a forearc setting the border ranges fault system brfs locally separates supracrustal upper cretaceous tertiary rocks of the cook inlet matanuska valley forearc basin on the peninsular terrane from metamorphosed cretaceous subduction complex rocks of the chugach terrane to the south this 5 to 10 km wide zone of concentrated deformation along the inboard edge of southern alaska s accretionary prism has suffered a protracted history beginning with its inception as a megathrust by early cretaceous time and continuing into early tertiary time when it was transected by a system of steeply arcward dipping normal and dextral slip faults based on detailed geologic mapping structural analysis metamorphic mineral assemblage data and k ar and fission track geochronology the tertiary history of displacements along a central part of this forearc fault system has been divided into several phases of deformation these include a paleocene phase of regional uplift of the forearc basin together with block faulting along the brfs to rapidly uplift and subaerially expose low grade metamorphic rocks of the subduction complex upper cretaceous valdez group within 15 ma of their inferred underplating at deep structural levels of the accretionary prism continued normal separation faulting along the brfs in late paleocene early eocene time to further uplift the subduction complex was recorded by deposition of a syntectonic alluvial fan system chickaloon formation across the brfs and along the southern margin of the forearc basin a third mid eocene increment of normal separation faulting along the brfs juxtaposed greenschist facies fabrics of early eocene age in the subduction complex against the chickaloon formation this latter uplift event predated intrusion of early late eocene 43 48 ma zircon fission track minimum ages felsic dikes into the present terrane bounding fault and was accompanied by no more than a few tens of kilometers of dextral slip faulting along the brfs a conclusion that does not accord with recent suggestions for thousands of kilometers of displacement along that fault system in early middle tertiary time based on paleomagnetic data field observations in the study area indicate that the great oroclinal bend of southern alaska is postearly eocene and possibly prelate oligocene in age a final period of deformation in middle to late tertiary time was marked by periods of minor north south contraction of the forearc basin and by local reverse slip reactivation of earlier faults fission track age data on apatite indicate rapid cooling and probably uplift of both subduction complex and adjacent parts of the forearc basin in miocene time 17 24 ma episodic uplift of the subduction complex either locally by normal separation faulting along its backstop or by a more regional uplift also affecting the adjacent forearc basin overlapped in time or closely followed discrete pulses of large scale sediment underplating along the gulf of alaska subduction margin this coincidence suggests that major pulses of sediment underplating along southern alaska s convergent margin may have led to isostatic uplift of its critical taper accretionary prism an uplift that was in part accommodated by normal separation faulting along its mechanical backstop

late cretaceous through cenozoic strike slip tectonics of southwestern alaska abstract new geologic mapping and geochronology show that margin parallel strike slip faults on the western limb of the southern alaska orocline have experienced multiple episodes of dextral motion since 100 ma these faults are on the upper plate of a subduction zone 350 450 km inboard of the paleotrench in southwestern alaska dextral displacement is 134 km on the denali fault at least 88 94 km on the iditarod nixon fork fault and perhaps tens of kilometers on the dishna river fault the strike slip regime coincided with late cretaceous sedimentation and then folding in the kuskokwim basin and with episodes of magmatism and mineralization at 70 60 and 30 ma no single driving mechanism can explain all of the 95 million year history of strike slip faulting since 40 ma the observed dextral sense of strike slip has run contrary to the sense of subduction obliquity this may be explained by northward motion of the pacific plate driving continental margin slivers into and or around the oroclin

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

geographic and seasonal distributions of brunt vaisala frequency and rossby radii in the north pacific and north atlantic abstract long term mean temperature and salinity profiles computed from an edited set of historical hydrographic data have been used to calculate mean profiles of density and brunt vaisala seasonal variations in internal rossby radii are everywhere surprisingly small

interannual variability of the kuroshio transport in response to the wind stress field over the north pacific its relation to the path variation south of japan we have investigated the interannual variability in the kuroshio transport focusing on the baroclinic response of the upper ocean to the long term variation of the wind stress field over the north pacific from 1961 to 1987 first temporal change of the kuroshio transport at the western boundary from 17 to 31 n has been estimated on the assumptions that the kuroshio is a baroclinic flow confined in the upper layer and that the effect of interior wind stress curl on the volume transport at the western boundary is transferred by nondispersive baroclinic rossby wave peak values in the estimated transport appear in its beginning region 17 21 n when or just before the kuroshio settles into a meandering state south of japan in 1975 1981 and 1986 these peaks are due to negative wind stress curl anomalies which are induced by the intensified trade winds in the central and eastern tropical north pacific on and just after an el nino event and in the western tropical north pacific months to years before the next el nino event such peaks are not found in the barotropic sverdrup transport in downstream regions i e in the east china sea and south of japan north of 23 n on the contrary the estimated transports through baroclinic and barotropic responses do not have such good correlation to the path variation temporal change in thermocline depths estimated from bathythermograph data clearly shows the westward propagations of positive anomalies by nondispersive baroclinic rossby waves at latitudes of the beginning of the kuroshio south of 21 n which is in phase with peaks of the kuroshio baroclinic transport at the western boundary on the other hand there are only the local propagations of the anomalies in the downstream regions as previous studies reported however it is emphasized that temporal change of the geostrophic transport in the east china sea 28 n is coincident with that of the baroclinic transport at the beginning of the kuroshio not with that at the same latitude a numerical experiment with a nonlinear reduced gravity model confirms that temporal changes of the transport in the east china sea and south of japan are due to the advective nonlinear effect of the kuroshio itself while the linear baroclinic response to the wind stress field is dominant in its beginning region

evolution of the north pacific subtropical gyre during the past 190 kyr through the interaction of the kuroshio current with the surface and intermediate waters the north pacific subtropical gyre npsg has two important functions i e one in ocean heat transfer and another as a driving force for circulation of the surface and intermediate waters on the basin scale in the present study we describe records of the vertical thermal structures and distributions of water masses in the upper ocean of the subtropical northwest nw pacific for the past 190 kyr using two sediment cores collected from the kuroshio current area in the east china sea and the npsg area during the two glacial periods the kuroshio current was weakened owing to changes in ocean atmosphere circulation and eustasy the differences in the mg ca derived temperatures between surface and thermocline waters show the changes of depth and temperature warming of thermocline during glacial periods conversely the planktonic foraminiferal assemblages demonstrate that the indicator of the intermediate water from the central area of the npsg increased synchronously with thermocline warming during marine isotope stage mis 6 these results suggest that warm intermediate water strongly affected the changes in the water column structure of the subtropical nw pacific during mis 6 however during mis 2 cold water had precedence over intermediate water probably owing to the southward shift of the subtropical front associated with the reduced transport of the kuroshio current thus the npsg has evolved differently during the two glacial periods mis 2 and mis 6 through interactions between the kuroshio current surface water and intermediate water

varieties of a single cosmopolitan diatom species associated with surface water masses in the north pacific abstract a time series of 65 sediment trap samples representing 48 month changes in diatom flora and 62 sediment core tops from the western north pacific ocean were analyzed varieties of a single diatom species were found to be characteristic of two surface water masses bounded by the kuroshio current thalassionema nitzschioides var incurvata var inflata and var parva dominate in warm saline waters in the subtropical gyre while t nitzschioides sensu stricto is abundant in less saline waters northwest of this current time series data on percent abundances for the three t nitzschioides varieties in the t nitzschioides complex are compared with path variations of the current south of japan inter annual fluctuations in percent abundance are linked to changes in surface water masses over the sediment traps in association with migration of the kuroshio paths this finding makes the percent abundance a useful tool for deciphering path migrations of the kuroshio current in the geologic past down core analyses of two sediment cores collected beneath the modern kuroshio current were performed a sharp increase in percent abundances from 12 to 9 kyr bp with an abrupt change around 11 kyr bp records the previously reported transition of the kuroshio current from a predominantly offshore path to its modern path path migrations of the kuroshio current may be inferred from percent abundances of these diatoms which comprise a new proxy for delineating the paleoclimate of the northwestern pacific in relation to changes in northward heat transport from the western equatorial pacific ocean by the western boundary current

space time statistics of short term climatic variability in the western north pacific temperature observations routinely taken over a period of years are analyzed for information on the space time statistical structure of the short term climate related variability in the western north pacific observations were taken by the rv ryofu maru making winter hydrographic transects along 137 e from japan to the equator each year from 1967 1974 and by the japanese far seas fisheries agency making 120 quasi meridional bathythermograph sections between 125 e and 180 from japan to the equator during 1968 1972 meridional wave number spectra of subsurface temperature over the depth range 100 300 m are calculated from the sections spectra vary significantly between the tropical region south of 17 5 n and the subtropical region north of 17 5 n in both regions wave number spectra increase in spectral energy density as the inverse square of the wave number from wavelengths of 200 1200 km this indicates that the spectra derive from a first order autoregressive process decorrelation scales associated with the first order process are very different for the two regions evaluation of these parameters is obtained by fitting the observed wave number spectra with a model spectrum that is composed of a first order autoregressive process and a white noise process the best fit decorrelation scale of the first order process is 600 km in the tropics south of 17 5 n and 300 km in the subtropics north of 17 5 n the model permits the partition of temperature variance into climate related signal variance and noise variance that cannot be resolved by routine monitoring the ratio of noise to signal variance is 0 3 in the tropics and 1 0 in the subtropics estimates of the time and zonal space decorrelation scales are determined from autocorrelation analysis of the japanese far seas fisheries agency temperature data both north and south of 17 5 n the decorrelation time scale in the subsurface temperature is approximately 6 months the zonal decorrelation length scale in the subsurface temperature is approximately 10 longitude for the tropical region south of 17 5 n but only about 2 5 longitude for the subtropical region north of 17 5 n for equal time scales it is shown that the spectral shapes and the latitudinal differences in zonal space scale are consistent with the representation of upper ocean thermal variability in terms of nondispersive baroclinic long waves i e rossby waves discussed are implications of this space time statistical information on the design of monitoring networks used to detect shor term climate related variability in thermal structure

interannual fluctuations of the tropical pacific wind field and the southern oscillation abstract linear regression analysis of tropical pacific winds versus a southern oscillation index soi show departures from the seasonal mean wind associated with the phase of soi when the soi is low the largest departures are westerlies on the equator and in the subtropics west of the dateline the intertropical convergence zone itcz and the south pacific convergence zone spcz shift equatorward departures from mean wind are strongest from september through february and weakest from march to may the usual pattern of cyclonic wind stress curl in the tropics and anticyclonic wind stress curl in the subtropics intensifies when the soi is low effects of these changes on ocean circulation are discussed and compared to changes in ocean circulation data

off equatorial influence upon pacific equatorial dynamic height variability during the 1982 1983 el nino southern oscillation event anomalous sea level anomalous observed dynamic height 0 400 dbar and anomalous model dynamic height are compared at the locations of 13 island sea level stations in the tropical pacific for each 2 month interval of the 4 year period 1979 to 1982 sea level compares well with both observed dynamic height 0 400 dbar based on temperature depth observations made by volunteer observing ships and model dynamic height derived from a linear two layer wind driven model the cross correlation between sea level and either of the dynamic heights is generally greater than 0 75 the ratio of root mean square rms differences about the mean annual cycle of the sea level to rms differences of either of the dynamic heights is approximately unity starting in 1981 off equatorial rossby wave activity propagated toward the western boundary of the pacific basin this also occurred in model dynamic height both north and south of the equator yet neither sea level observations nor observed dynamic height has the spatial and temporal resolution to establish a connection between the off equatorial rossby wave activity and the equatorial kelvin wave activity in the western boundary region on the other hand the model dynamic height does have this capability therefore at the western boundary the model rossby wave activity is found to have excited coastally trapped kelvin munk wave activity which transmitted the anomalous sea level equatorward at the equator this model coastally trapped wave activity excited eastward propagating equatorial kelvin waves yielding a pair of anomalous peaks in dynamic height variability in the eastern equatorial pacific associated with the 1982 1983 el nino southern oscillation enso event the evolution of these two peaks in anomalous dynamic height associated with the 1982 1983 enso event is examined at eight locations in the tropical and equatorial pacific the major peak originated in the off equatorial south pacific and coincided with the wintertime 1982 1983 el nino event in the eastern equatorial pacific the secondary peak originated in the off equatorial north pacific and coincided with the anomalous peak which occurred in the eastern equatorial pacific the summer before the 1982 1983 enso event

stable paths of the kuroshio south of japan determined by the wind stress field 1 to investigate the role of the wind stress field in determining stable paths of the kuroshio south of japan we have executed numerical experiments with a two layer wind driven ocean model changing zonal and meridional wind stress distributions four types of path two straight and two meandering paths have been found and their appearance has been classified into three categories in category i straight and meandering paths coexist multiple equilibrium only a meandering straight path appears in category ii iii a meandering path tends to appear when the sverdrup transport along the southern coast of japan decreases downstream strongly and the wind stress curl is anomalously negative in the western region near japan whereas a straight path is apt to occur with the positive anomaly detailed examination of the results has revealed the following mechanism determining stable paths of the kuroshio the wind stress field first determines the pressure difference p between the two ends of the southern coast of japan when p is smaller than a certain threshold only a meandering path can exist since the along coast pressure decrease in a straight path state is much larger than p category ii conversely when p is larger than another threshold only a straight path is consistent with the larger p category iii both paths can appear when p is between the two thresholds category i the climatological wind stress field in the north pacific subtropical region has been suggested to be in category i

effects of large scale wind on the kuroshio path south of japan in a 60 year historical ogcm simulation the effects of large scale wind forcing on the bimodality of the kuroshio path south of japan the large meander lm and non large meander nlm were studied by using a historical simulation 1948 2007 with a high resolution ocean general circulation models ogcm the kuroshio in this simulation spent much time in the nlm state and reproduced several aspects of its long term path variability for the first time in historical ogcm simulation presumably because the eddy kinetic energy was kept at a moderate level by using the simulated fields the relationships between wind forcing or kuroshio transport and path variation proposed by past studies were tested and specific roles of eddies in those variations were investigated the long term variation of the simulated net kuroshio transport south of japan was largely explained by the linear baroclinic rossby wave adjustment to wind forcing in the simulated lm events a triggering meander originated from the interaction of a wind induced positive sea surface height ssh anomaly with the upstream kuroshio and was enlarged by cyclonic eddies from the recirculation gyre the cyclonic eddy of the trigger meander was followed by a sizable anticyclonic eddy on the upstream side subsequently a weak strong kuroshio favored the lm nlm the lm tended to be maintained when the kuroshio transport off southern japan was small and increasing kuroshio transport promoted decay of an existing lm the supply of disturbances from upstream which is related to the wind induced ssh variability at low latitudes contributed to the maintenance of an existing lm

cenozoic non marine sedimentary rocks of the farewell fault zone mcgrath quadrangle alaska abstract cenozoic non marine clastic rocks crop out discontinuously along the denali fault system of south central alaska the western limit of these rocks is along the farewell fault in the windy fork cheeneetnuk river area regionally the farewell fault zone is near the boundary between paleozoic carbonate rocks of western alaska and the polymetamorphic rocks of east central alaska the lower to middle tertiary clastic units were deposited by south flowing fluvial systems draining a low grade metamorphic provenance measured sections of these clastic rocks show a general fining upward from massive amalgamated conglomerate to thinly laminated shale the depositional environment is interpreted to have been braided stream channels and interchannel overbank systems succeeded by a lacustrine and marsh environment the source of upper tertiary conglomerate was probably the rising alaska range to the south the position of the cenozoic rocks and inferred motion of the farewell segment is similar to other portions of the denali fault and suggests that similar tectonics and sedimentation have existed throughout central alaska since early tertiary time

a mesozoic time scale we present an integrated geomagnetic polarity and stratigraphic time scale for the triassic jurassic and cretaceous periods of the mesozoic era with age estimates and uncertainty limits for stage boundaries the time scale uses a suite of 324 radiomenc dates including high resolution 40 ar 39 ar age estimates this framework involves the observed ties between 1 radiometric dates biozones and stage boundaries and 2 between biozones and magnetic reversals on the seafloor and in sediments interpolation techniques include maximum likelihood estimation smoothing cubic spline fitting and magnetochronology

the intrusion of water masses into the sea southwest of taiwan characteristics of water masses were analyzed to study the kuroshio intrusion into the sea southwest of taiwan hydrographic data were obtained from ctd conductivity temperature and depth casts during two cruises in may and august 1986 in may remnants of water intruding from the kuroshio were found on the continental slope south of the penghu channel by august these were replaced by water from the south china sea during this period water from the kuroshio also appeared near the southern tip of taiwan the intrusion current reached a depth of at least 500 m and was probably part of a cyclonic circulation in the northern south china sea the results support the hypothesis of a seasonal pattern of the intrusion process intrusion of water from the kuroshio begins in late summer intensifies in winter and ceases by late spring when south china sea waters again enter this region

interannual variability in the mid and low latitude western north pacific abstract twenty two years 1967 88 of hydrographic data collected by the japan meteorological agency along the 137 e meridian and surface wind data compiled by florida state university fsu were analyzed to study the interannual variability in the western north pacific in the midlatitude region north of 22 n the dominant signal in the dynamic height field was the interannual path variations of the kuroshio whereas the eastward transport of the kuroshio itself had no significant changes between the straight path and meander path years the net transport of the kuroshio system including recirculations showed a 30 increase during the meander path years in the straight path years when the net transport was small the kuroshio tended to take a straight path with a strong recirculation developed to the south the interannual path variations of the kuroshio strongly influenced the water mass movement in the midlatitudes during the kuroshio meander years we found that a significant portion of the north p

traveling wave like mesoscale perturbations in the north pacific current abstract individual seasonal mean maps of temperature at 300 m in the north pacific current cast of 180 from 1976 to 1980 were constructed from transpac xbt data the long term annual mean map is relatively smooth with some weak quasi stationary meander activity most of the total variance was due to large scale interannual variability i e 60 loss to the mesoscale perturbations i e 30 and least to the annual cycle i e 10 however individual mesoscale perturbations were significant clearly wave like with a wavelength scale of 500 1000 km and a period scale of 1 2 years and generally coherent in phase over 10 of latitude these wave like mesoscale perturbations emanated from the eastern boundary and propagated westward as coherent features at the phase speed of linear non dispersive baroclinic long waves the latitudinal reduction in phase speed from 2 7 cm s 1 at 35 n to 1 4 cm s 1 at 45 n was consistent with baroclinic long wave theory an increase in time scale of these wave l

interannual variability of the kuroshio onshore intrusion along the east china sea shelf break effect of the kuroshio volume transport the interannual variability of the kuroshio onshore intrusion koi across the east china sea ecs shelf break and its response to the ecs kuroshio volume transport kvt during 1993 approximate to 2010 are studied based on a high resolution real time and global ocean general circulation model since variability of kvt is mainly determined in the interior pacific it is rather a remote than a local factor for the local ecs koi on interannual time scales kvt affects koi not only in the net volume transport across the entire shelf break but also in the spatial pattern along the shelf break when kvt increases the intrusion decreases increases upstream downstream of the major intrusion region northeast of taiwan the retreating increases decreases upstream downstream of the main veering region southwest of kyushu these patterns are caused by cyclonic eddies induced by the seaward deflection of the kuroshio axis from the shelf break which ultimately results from the kvt increase a diagnostic mechanism of koi approximate to msin delta h 1 is proposed where h is the bottom depth is the angle between isobaths and the vertically averaged current and m is the absolute volume transport at the shelf break is large in the major intrusion retreating regions and stable on interannual time scales while m changes with opposite signs between upstream and downstream of the major intrusion retreating regions the mechanism explains well the relation of local kvt and the spatial pattern of koi along the shelf break in both the mean state and the interannual variations

new perspectives on the generation and maintenance of the kuroshio large meander abstractthe internal dynamical processes underlying the kuroshio large meander are investigated using a recently developed analysis tool multiscale window transform mwt and the mwt based canoni

seismic characteristics and identification of negative flower structures positive flower structures and positive structural inversion negative and positive flower structures and positive inverted structures imply specific modes of formation and their distinctive characteristics make them important criteria for the identification of certain structural styles a negative flower structure from the andaman sea consists of a shallow synform bounded by upward spreading strands of a wrench fault that have mostly normal separations paralleling monoclines and oblique en echelon normal faults flank the divergent wrench fault a positive flower structure from the ardmore basin oklahoma consists of a shallow antiform displaced by the upward diverging strands of a wrench fault that have mostly reverse separations en echelon folds are present on either side of this convergent wrench fault flower structures may resemble extensional or contractional fault blocks on individual seismic profiles flower structures are identified by their unique internal fault and fold architecture by their association with a straight and throughgoing zone of deformation and by their lack of a consistent sense of separation or regional upthrown side positive structural inversion at the rambutan oil field south sumatra basin has formed a shallow anticlinorium and has partly uplifted the underlying graben deeper fault segments bounding the graben have retained their normal fault profiles but at shallow levels some of these faults have reverse separations similar changes of separation with depth may be produced by strike slip but sets of faults with listric profiles and nearby blocklike trend patterns identify the inversion as a dip slip event where correlation of reflections is uncertain or deep control is unobtainable positive inverted structures may also resemble contrational fault blocks detached normal fault assemblages and certain negative inverted structures

kinematics of basin development during the transition from terrane accretion to strike slip tectonics late cretaceous early tertiary cantwell formation south central alaska the cantwell basin was formed during late cretaceous time in the suture zone between the wrangellia composite terrane and the former continental margin of southern alaska the late cretaceous 80 70 ma lower cantwell formation represents the initial fill of this basin and includes 4000 m of sedimentary rock between maastrichtian and late paleocene time 70 60 ma rocks of the lower cantwell formation were deformed by nearly eastwest trending folds and north vergent thrust faults this deformation can be linked to the northward accretion and suturing of the wrangellia composite terrane to southern alaska during late paleocene to early eocene time 60 55 5 ma at least 2750 m of volcanic rocks of the upper cantwell formation were deposited above the folded lower cantwell formation new 40ar 39ar ages for the upper cantwell formation range from 59 8 0 2 to 55 5 0 2 ma and reveal that the unconformity between the lower and upper cantwell formations represents a 10 20 million year hiatus following volcanism the cantwell formation was crosscut by northeast trending folds northwest trending normal faults north trending left lateral slip faults northeast trending reverse faults and east trending right lateral slip faults these structures are consistent with northwest southeast compression in a zone of right lateral simple shear along a fault with the same trend east northeast as that of the present mckinley strand of the denali fault system cantwell basin kinematics are compatible with an escape tectonics model for south central alaska whereby the cantwell basin was formed folded and partially uplifted during northward terrane accretion and suturing and was deformed again during the westward transfer of terranes along right lateral strike slip fault systems

major dextral transcurrent displacements along the northern rocky mountain trench and related lineaments in north central british columbia the northern rocky mountain trench and a number of other prominent lineaments along and east of the eastern margin of the intermontane belt mark faults along which dextral transcurrent movements have been dominant offsets of shelf to off shelf facies boundaries in lower paleozoic rocks indicate a cumulative displacement of at least 750 km and probably 900 km within the system of faults related to those in the northern rocky mountain and the tintina trenches farther west another system of faults appears to offset plutons and stratigraphic assemblages along the eastern margin of the intermontane belt by as much as 300 km these faults including the kutcho and the pinchi connect in part with the teslin suture zone in yukon territory and probably with the fraser river straight creek fault zone in southern british columbia although dextral transcurrent faulting may have taken place between the middle jurassic and early cenozoic the most convincing evidence points to middle cretaceous and particularly to early cenozoic eocene displacements the eocene movements were temporally related to plutonism volcanism lamprophyre dike emplacement high heat flow sedimentation in grabens and rapid uplift of northwesterly trending elongate ranges climactic episodes of granite emplacement particularly in and near the northern omineca crystalline belt at 100 m y 70 m y and 50 m y ago may have been facilitated by changes from dominantly compressional to dominantly transcurrent and related tensional strain

bimodality of the kuroshio abstract a barotropic ocean model is used to study the bimodal behavior of the kuroshio to the south of japan by considering the combined effects of the beta plane the kyushu coastal perturbation the izu ridge and the sw ne tilted coastline the two frequently observed meander patterns have been numerically verified as the two quasi steady solutions contained n the model the small meander state is identified as an upstream disturbance largely forced by the izu ridge its width decreases as the strength of the current increases the large meander state is forced by the presence of both the kyushu wedge and the izu ridge topography for small volume transports the large meander state behaves like the small meander state in that the meander width decreases as the current speed increases for large volume transports it behaves like a lee rossby wave in that the width of the meander increases as the current speed increases the birth of the large meander state occurs as a consequence of the ocean spin do

climatically induced floristic changes across the eocene oligocene transition in the northern high latitudes yukon territory canada global temperature decline associated with the eocene oligocene transition resulted in extinctions of plants and animals in both marine and nonmarine environments the extensive stratigraphic exposures well preserved palynological assemblages and interbedded coal seams of the nonmarine amphitheatre formation burwash basin yukon territory provide a comprehensive record of this transition the formation spans a paleoclimatically significant interval otherwise poorly represented in high latitude deposits of the northwestern cordillera palynological data constrained by the chronologic and stratigraphic framework established for the amphitheatre formation indicate that the global temperature decline resulted in a shift from warm temperate angiosperm dominated to cooler temperate gymnosperm dominated mainly coniferous forest types this turnover is seen in the increase in the percentage of gymnosperm compared to angiosperm pollen upsection the effect of climate change is also recorded in the systematic composition of the angiosperm pollen spectra the highly diverse palynoflora of the lower amphitheatre formation is dominated by angiosperm pollen characteristic of plants favoring warm temperate climates and consistently includes pollen of broad leaved evergreen taxa in contrast the angiosperms most conspicuous in the low diversity palynoflora of the upper amphitheatre formation are characteristic of plants favoring a cooler temperate climatic setting petrographic compositional changes in the coals document the same plant community changes the floristic data also indicate that at high latitudes there may have been a change to a wetter and less seasonal climate during the overall global cooling trend

kuroshio path variation south of japan 1 barotropic inflow outflow model we examined the dynamics of the variation in the path of the kuroshio current along the south coast of japan by use of a barotropic inflow outflow ocean model the model basin has an inclined coastline and includes a part of the east china sea so that we could investigate the effect of kyushu on the kuroshio we obtained three regimes of the kuroshio s path variation according to the magnitude of its inlet velocity vmax similar to the previous study the kuroshio takes a straight path along the south coast of japan in regime i with a low vmax a meandering path in regime ii with a high vmax and both of these paths multiple equilibrium state in regime iii with an intermediate vmax the transition from the straight state to the meandering state occurs with an increase in vmax from regime i iii to ii preceded by an eastward progression of a small meander which is produced as a separated vortex by the nonlinear effect of the flow and the effect of kyushu it takes 120 days consistent with observations the nonlinearity of the flow has two effects in the transition one causes a downstream shift of the small meander and the other enlarges it by pulling out positive vorticity from the no slip coast with an increase in the meander scale due to the latter effect the former effect becomes small to be balanced with the beta effect causing an upstream shift of the meander thus a large meander path is formed a small meander does not progress eastward to develop into a large meander until vmax exceeds a critical value this behavior causes a multiple equilibrium state in regime iii and only the meandering path in regime ii

thrust top basin formation along a suture zone cantwell basin alaska range implications for development of the denali fault system the cantwell formation consists of a lower sedimentary sequence as much as 4000 m thick and an upper volcanic sequence with a maximum thickness of 3750 m that was deposited in the cantwell basin south central alaska previous to this study the cantwell basin was interpreted as a paleogene nonmarine mainly fluvial pull apart basin that formed in response to dextral strike slip displacement on the denali fault system this study proposes that the cantwell basin formed as part of the mesozoic accretionary phase of deformation prior to the development of the cenozoic postaccretionary denali fault system our reinterpretation is based on several new lines of data 1 age new data based on palynologic analyses of 135 fine grained samples indicate that the lower cantwell formation was deposited during the late campanian and early maastrichtian on the basis of previous regional tectonic studies and this new age constraint the formation of the cantwell basin was coeval with regional late cretaceous shortening associated with accretionary tectonics in southern alaska 2 depositional systems our analysis of the cantwell formation demonstrates that sedimentation occurred mainly in stream dominated alluvial fan axial braided stream and lacustrine settings these depositional systems were strongly influenced by a southward dipping asymmetric basin floor the presence of abundant terrestrially derived organic material together with palynological assemblages that include marine dinoflagellates and the associated presence of oncolites may be suggestive of a time of marginal marine influence during the deposition of the upper part of the lower cantwell formation the late campanian to early maastrichtian timing of this possible marine influence is within the range of the bearpaw transgressive event of the cordilleran foreland basin and allows for regional stratigraphic correlation of the cantwell basin with other sedimentary basins in northwestern north america 3 structural controls on basin formation mapping of intraformational angular unconformities and progressively tilted strata along the southern margin of the cantwell basin provides direct evidence that thrust fault deformation and lower cantwell formation sedimentation were synchronous distinctive cantwell formation conglomerate clasts derived from the uplifted hanging walls of nearby thrust sheets adjacent to the southern basin margin also support a syndepositional thrusting interpretation provenance data and the concentration of proximal alluvial fan deposits along the northwestern basin margin adjacent to the hines creek fault indicate that it too was active during deposition of the cantwell formation on the basis of the new data the cantwell basin is interpreted to have formed as a thrust top basin i e piggyback basin along the late cretaceous suture zone between the accreting wrangellia composite terrane and the north american continental margin in contrast to previous studies this reinterpretation of the formation of the cantwell basin implies that the lower cantwell formation is not a synorogenic deposit directly associated with strike slip displacement along the denali fault system therefore the cantwell basin cannot be used to constrain the timing for the early development of the denali fault system

dynamics of the kuroshio large meander two layer model abstract a simple two layered in outflow model is studied to explain the peculiarity of the kuroshio path the geometry south of japan with a length scale l and the characteristic velocity u of the kuroshio give an important parameter 2 u l the kuroshio can take two kinds of paths for a given value of multiple equilibria one is straight path and the other a meandering path the selection of a path the selection of a path in a multiple equilibrium state depends upon the history of the parameter the hysteresis phenomenon the combined effect of horizontal viscosity along the coast and the inclination of the coastline are essential factors which control the kuroshio path as well as an increase in the coastline inclination increases the effect of horizontal viscosity along the coast where a western boundary layer is formed due to the effect of an increase in the viscous effect along the coast makes a straight path possible when the inlet velocity is small the effect of stratification i

terrane motion by strike slip faulting of forearc slivers forearc slivers bounded by a trench and an active strike slip fault occur in about 50 of modern subduction zones analysis of earthquake slip vectors indicates that modern sliver terranes typically migrate at rates of 1 2 cm yr tertiary transport of some forearc slivers by 1000 km or more is therefore expected as a consequence of normal subduction active arc parallel strike slip faulting occurs whenever interplate coupling is strong and convergence is somewhat oblique strike slip rate increases with greater convergence obliquity

millennial scale variability of holocene hydrography in the southwestern okhotsk sea diatom evidence diatom analysis of two submarine cores off eastern hokkaido island northern japan provides insights into the holocene palaeoenvironmental history of the southwestern okhotsk sea diatom flora was

processes of short term climatic variability in the baroclinic structure of the interior western tropical north pacific abstract a realistic simulation of short term climatic variability in the relative dynamic height of the interior western tropical north pacific 4 22 n 127 e 180 for 9 years 1966 74 was conducted using a two layer wind driven baroclinic long wave model results of this model were compared with bimonthly maps of observed dynamic height 0 400 db for the region constructed by white and hasunuma from all available temperature depth observations for the same period the interannual rms differences about the mean annual cycle of the model dynamic height had a spatial pattern over the region of interest that was nearly identical to that observed with maximum values i e 3 5 and 4 5 dyn cm respectively in the vicinity of the north equatorial ridge at 15 n and minimum values i e 2 0 and 3 5 dyn cm respectively in the vicinity of the north equatorial ridge at 15 n and minimum values i e 2 0 and 3 5 dyn cm respectively in the countercurrent trough at 7 n model frequency spectra were ident

the mckinley sequence of granitic rocks a key element in the accretionary history of southern alaska the mckinley sequence of granitic rocks consists of several discrete plutons in the central alaska range most of these plutons crop out south of the denali fault system dfs in the talkeetna quadrangle plutons of the mckinley sequence largely intrude deformed upper meszoic flysch between the dfs and the northern edges of wrangellia and the peninsular terrane which jointly make up the talkeetna superterrane the average k ar age of biotite from nine granites of the mckinley sequence is 57 3 ma rb sr data for whole rock samples indicate that the mckinley sequence cannot be older than 60 ma a selected suite of 20 samples of granite and granodiorite range in sio2 from 65 9 to 77 6 all 20 samples are corundum normative and 18 are moderately peraluminous initial 87sr 86sr ratios range from 0 7054 to 0 7085 the 18o values range from 11 2 to 14 6 these high and variable sr isotopic ratios peraluminous nature rare earth element patterns and high 18o values suggest that granitic rocks of the mckinley sequence crystallized from hybrid magmas produced by assimilation of sedimentary rocks by a mantle derived melt mesozoic flysch is the likely source of the crustal component of the hybrid magmas geologic evidence suggests that the talkeetna superterrane collided with stable alaska after early cretaceous time the flysch basin lying south of stable alaska was closed by northward movement of the talkeetna superterrane maximum age for basin closure and terrane accretion is middle cretaceous cenomanian paleomagnetic evidence indicates that all terranes north of the dfs have been part of stable alaska since the paleocene and that northward movement of wrangellia was completed by 50 ma granitic rocks of the mckinley sequence may be products of terrane accretion the granitic rocks crystallized from hybrid magmas produced during terrane collision and deformation of the flysch basin isotopic ages of the mckinley sequence establish the time of final accretion of the talkeetna superterrane as paleocene

relationships between plate motions and late cretaceous to paleogene magmatism in southwestern alaska four major late cretaceous to paleogene magmatic belts have been recognized in southwestern alaska and tentative boundaries have been drawn for each the belts indicate minimum ages by which the tectonostratigraphic terranes they overprint must have been linked together though there has been significant postmagmatic tectonism the kuskokwim mountains belt 73 60 m y b p the alaska range belt 74 55 m y b p and the gulf of alaska belt 62 57 m y b p all may have been related to a period of rapid north northeastward motion of the kuia plate from about 74 to 56 m y b p the angle of convergence was low with respect to the present orientation of the belts suggesting the possibility of postmagmatic rotation of the belts a higher angle of convergence may have existed with respect to the alaska range belt a probable arc if postmagmatic rotation resulted from 300 400 km of right lateral displacement on the denali fault the gulf of alaska belt is in an anomalous forearc position with respect to the alaska range belt but probably formed by a convergence related mechanism the kuskokwim mountains belt is in an apparent back arc position but the mechanism of its origin is uncertain it may have been part of an unusually broad alaska range arc or less likely it may have been a separate arc magmatic quiescence occurred throughout south western alaska during a period of plate reorganization from about 56 to 43 m y b p a period which began with extremely rapid northward motion of the kuia plate magmatism resumed when the present period of rather slow northwestward pacific plate motion began at about 43 m y b p the aleutian arc probably formed at this time and has been episodically active in about the same location ever since

sources of interannual baroclinic waves in the eastern subtropical north pacific abstract subsurface temperature and surface salinity observations along the great circle transect between san francisco and honolulu are used to investigate the source of annual baroclinic long waves in the eastern subtropical north pacific ocean long term mean 15 day values 1966 74 of depth of the 9 c isotherm indicative of thermocline depth and of surface salinity are each fit by least squares method with a time varying cosine yielding phase and amplitude of the mean annual cycle at standard locations every 92 6 km 50 mi along the transect local wind stress curl is expected to influence the observed depth of the 9 c isotherm through the mechanism of ekman pumping therefore its annual cycle is computed in a manner like that of the depth of the 9 c isotherm and its effect removed from the latter the residual annual cycle has phase and amplitude profiles along the transect that closely resemble that of model annual baroclinic long waves emanating from a line source of large amplitude wind st

interannual variability of the kuroshio frontal structure along its western boundary in the north pacific ocean associated with the 1982 enso event abstract the vertically averaged temperature tav over the upper 200 m of ocean in the western boundary of the north pacific is used to detect changes in the strength and path of the kuroshio front along the western boundary from luzon 18 n to honshu 34 n during the period 1979 82 during this time the kuroshio front experienced significant interannual changes associated both with the disappearance of the kuroshio meander in late 1980 and with the development of the 1982 enso event in early 1982 when the kuroshio meander south of honshu disappeared from the fall of 1980 until the summer of 1981 the intensity of the kuroshio front increased associated with warmer than normal temperatures all along the western boundary of the north pacific from luzon to honshu the amplitude of the kuroshio meander was also correlated with fluctuations in the path of the kuroshio front at the tokara strait 30 n and the bashi strait 20 n and with the amplitude of the east china sea meander the east china sea me

seasonal to interannual variations in the intensity and central position of the surface kuroshio east of taiwan 1 seasonal and interannual changes of surface kuroshio intensity and central position east of taiwan during 1993 2012 are investigated by quantitatively analyzing the satellite altimetry product the kuroshio moves inshore offshore off northeast of taiwan in winter summer whereas it has an offshore inshore path off southeast of taiwan in winter summer the seasonal change of heat flux over the east china sea shelf is found to cause the seasonality of the kuroshio central position off northeast of taiwan whereas the seasonal kuroshio movement off southeast of taiwan is found to be induced by the combined effect of the kuroshio changes through the luzon strait and the eastern luzon island in contrast to this y dependent path changes the kuroshio becomes weaker stronger as a whole east of taiwan in winter summer on the interannual time scales the kuroshio throughout the eastern coast of taiwan intensifies and has a concurrent offshore path during the periods of 1995 1997 and 2004 2007 the relative intensity of cyclonic eddies to anticyclonic eddies off eastern taiwan are found to contribute to these interannual kuroshio changes

off equatorial westward propagating rossby waves in the tropical pacific during the 1982 83 and 1986 87 enso events abstract analysis of anomalous vertically averaged temperatures tav in the tropical pacific ocean for the eight year period 1979 86 finds the development during the onset phase one to two years before the mature phase of the two enso events of the period having dynamically significant similarities both north and south of the equator during the onset phase of both enso events each beginning in the off equatorial western tropical pacific about 10 latitude positive anomalies of tav occurred during northern autumn winter one year prior to the mature phase of each enso event in both northern and southern hemispheres this corroborates model results of pazan et al and supports the hindcasting forecasting capability of enso events obtained by white et al though the latter considered only the northern hemisphere it is also demonstrated that the development of positive tav anomalies in northern autumn winter along the tropical maritime western boundary of both hemispheres was associated with wind

denali fault system of southern alaska an interior strike slip structure responding to dextral and sinistral shear coupling the denali fault system dfs extends for 1200 km from southeast to south central alaska the dfs has been generally regarded as a right lateral strike slip fault along which post late mesozoic offsets of up to 400 km have been suggested the offset history of the dfs is relatively unconstrained particularly at its western end for this study we calculated relative motion vectors at discrete points along the length of the dfs based on the well understood kinematic interaction between the north american pacific and kula plates and the following assumptions 1 the arcuate geometry of the dfs has existed essentially unchanged since the late cretaceous 2 the yukon tanana terrane and other terranes north of the dfs were fixed in situ prior to the accretion of the southern alaskan terranes and 3 tangential and normal relative motion vector components calculated for points along the dfs using the plate model of kelley 1993 describe the plate kinematics of the dfs since the late cretaceous the consequent kinematic model for the dfs predicts that left lateral stresses have acted upon the western end of the dfs for much of its history and conflicting senses of shear exist between the eastern and western ends of the system the offset history of the western end of the denali fault system should be significantly different than the history of the central and eastern sections consequently individual crustal blocks in southeast and southwest alaska may have undergone respectively clockwise and counterclockwise rotations the sense of rotation predicted by our model is in agreement with rotations determined by paleomagnetic studies and provides an alternative model to the alaskan orocline hypotheses

effects of stratification and bottom topography on the kuroshio path variation south of japan part ii path transitions in a multiple equilibrium regime abstract the effects of stratification and bottom topography on the kuroshio path transitions in a multiple equilibrium regime due to a short term velocity increase are examined using a two layer inflow outflow model with simplified coastal geometry and bottom topography for an imposed velocity increase on a straight path state the typical transition from a straight to a meandering path occurs with or without bottom topography through the same process as in a barotropic case with flat bottom thus the geometrical effect of kyushu is essential to this transition or to the formation of a small meander triggering the transition stratification and bottom topography are somewhat secondary nevertheless under the influence of stratification a small meander significantly develops south of kyushu during a decreasing phase of velocity through shoaling of the interface depth and triggers the transition with the amplification rate of velocity amp of 1 5 the continental slope south of japan prevents a small me

hindcast forecast of enso events based upon the redistribution of observed and model heat content in the western tropical pacific 1964 86 anomalous sea level anomalous observed dynamic height 0 400 db and anomalous model dynamic height are examined at the locations of 13 island sea level stations in the tropical pacific for each bimonth of the four year period 1979 to 1982 starting in 1981 the anomalous dynamic height data show off equatorial rossby waves propagated toward the w boundary of the pacific basin at the w boundary the model rossby wave activity was found to have excited coastally trapped kelvin munk waves which transmitted the anomalous dynamic height equatorward at the equator coastally trapped wave activity excited eastward propagating equatorial kelvin waves yielding a pair of anomalous peaks in dynamic height variability in the e equatorial pacific associated with the 1982 1983 enso event the evolution of the peaks in dynamic height associated with the rossby and kelvin wave activity reflects the redistribution of observed upper ocean heat content in the w tropical pacific providing a qualitative hindcast for the 1982 1983 enso event

coupling of long oceanic waves in the pacific ocean and the rotating elastic earth during the 1986 1987 el nino we investigate interannual coupling between the rotating elastic earth and the ocean during the 1986 1987 el nino we find the e w component of the ground tilt at the esashi earth tides station up toward the east about 50 milliarc seconds mas a rise of sea level about 5 cm at chichijima and oshima in the northwestern pacific ocean and an increase of 1 cm in the very long baseline interferometry vlbi baseline distance between kashima japan and kauai hawaiian islands as well as the residual length of day lod changes of 50 s during the 1986 1987 el nino the residual lod is derived from elimination of changes in atmospheric angular momentum our discussions are based on the coupling between torsional motions of the elastic earth and reflection of the eastward traveling equatorial kelvin waves at the eastern boundary of the pacific ocean these equatorial waves exchange the momentum and the axial and zonal component of vorticity with the elastic earth during the 1986 1987 el nino reflection of the kelvin wave is expected to excite torsional motions and to couple with differential zonal rotation in the elastic earth and to generate anomalies of 1 6 s in lod the differential zonal rotation due to the torsional motion can produce the same order of the magnitude of changes in the vlbi baseline distance between kashima and kauai variations of the e w component of the tilt cannot be explained by torsional motion we infer that the midlatitude rossby waves are generated in the central pacific ocean this conclusion is consistent with sea level changes at chichijima and oshima and changes of the tilt at esashi

zircon shrimp u pb age of monuogechin monzodiorite of inner mongolia and its geological significance located in the south gobi dong ujimqin banner metallogenic belt of the china mongolia border and its neighboring areas the monuogechin lead zinc pre investigation area is a newly discovered lead zinc polymetallic deposit the exposed monzodiorite has an intimate relationship with the monuogechin lead zinc pre investigation area in order to determine the accurate age of the monuogechin monzodiorite the authors employed the zircon shrimp u pb isotope dating technology and obtained the age of 312 6 4 1 ma mswd 0 76 indica ting hercynian this age is essentially in agreement with the event of magmatism in the east of the erenhot dong ujimqin banner volcanic magmatic belt from 300 ma to 315 ma and the age of granites in the south gobi dong ujimqin banner copper polymetallic ore forming belt combined with regional data it is suggested that the erenhot dong ujimqin banner late carboniferous monzodiorite resulted from the crustal thickening melting of the intraarc rift tensional system this age provides important evidence for late carboniferous magmatism and helps guide the work related to lead zinc molybdenum copper polymetallic ore exploration in china mongolia border and its neighboring areas

spatial and temporal variability of surface water in the kuroshio source region pacific ocean over the past 21 000 years evidence from planktonic foraminifera abstract the kuroshio current is the major western boundary current of the north pacific ocean and has had a large impact on surface water character and climate change in the northwestern pacific region the kuroshio current becomes a distinctive surface flow in the ryukyu arc region after diverging from the north equatorial current and passing through the okinawa trough therefore the ryukyu arc area can be called the kuroshio source region we reconstructed post 21 ka time space changes in surface water masses in the ryukyu arc region using 15 piston cores which were dated by planktonic 18 o stratigraphy and ams 14 c ages our analysis utilized spatial and temporal changes in planktonic foraminiferal assemblages which were classified into the kuroshio subtropical coastal and cold water groups on the basis of modern faunal distributions in the study region these results indicate that the kuroshio current and adjacent surface water masses experienced major changes during 1 the last glacial maximum lgm and 2 the so called pulleniatina minimum event pme from 4 500 to 3 000 yr bp the kuroshio lgm event corresponds to severe global cooling and is marked by decreases in planktonic 18 o values and estimated sea surface temperature sst with the dominance of the cold water group of planktonic foraminifera cooling within the kuroshio source region was enhanced during the lgm event because the kuroshio current was forced eastward due to the formation of a land bridge between taiwan and the southern ryukyu arc which prohibited its flow into the okinawa trough except for the severe reduction and disappearance of the pulleniatina group no clear cooling signal was identified during the pme based on 18 o values estimated sst values and variations in the composition of planktonic foraminiferal faunas the pme assemblages are marked by high abundances of neogloboquadrina dutertrei a distinctive kuroshio type species along with other species assigned to the coastal and central water groups subtle ecological differences exist between pulleniatina obliquiloculata and n dutertrei i e p obliquiloculata exhibits lower rates of reproduction under conditions of lower primary productivity in the central equatorial pacific ocean el nino like conditions in the equatorial pacific ocean result in lower rates of surface transport in the kuroshio current in turn this response triggers lower rates of primary productivity in central equatorial surface waters as well as in the upstream kuroshio source region ultimately resulting in a lower abundance of p obliquiloculata thus we interpret the pme as a possible proxy signal of el nino like conditions and enhancement of the el nino southern oscillation climate system after the pme in the tropical and sub tropical pacific ocean

effects of stratification and bottom topography on the kuroshio path variation south of japan part i dependence of the path selection on velocity abstract numerical experiments are executed using a two layer inflow outflow ocean model with simplified geometry to investigate the effects of stratification and bottom topography on the path variation of the kuroshio south of japan in a flat bottom ocean the dependence of the kuroshio path selection on its inflow velocity vmax is basically the same as in a barotropic ocean that is the kuroshio takes a straight path at low vmax regime i a meandering path at high vmax regime ii and both paths at intermediate vmax regime iii multiple equilibrium state however the range of regime iii shifts to higher vmax by 0 10 0 30 m s 1 stratification causes and maintains the offshore shift of the current path south of kyushu through the conservation of potential vorticity as a result a small meander stagnates southeast of kyushu not developing into a large meander even for higher vmax since the vorticity supply from the coast is reduced for the same reason higher vmax is needed to maintain a meande