deformation at an archean subprovince boundary northern minnesota structural analysis in the northern margin of the quetico subprovince part of the archean superior province of the canadian shield in minnesota reveals that the main deformation involved polyphase folding f1 recumbent and nappe like and f2 upright east west trending and tight to isoclinal during regional ductile transpression and amphibolite facies metamorphism a younger deformation developed during the latter stages of regional transpression resulted in the generation of localized ultraphyllonites along the steeply dipping rainy lake seine river fault rlsrf the major fault separating the quetico subprovince from the rainy lake wrench zone a wedge shaped block between the quetico and wabigoon subprovinces the transpression involved north south shortening and east west dextral shear the presence of shear zones in amphibolite facies wall rock south of the fault and in lower grade ultraphyllonites within the rlsrf suggests that localization of shear occurred by work and or reaction softe

the upper level circulation anomaly over central asia and its relationship to the asian monsoon and mid latitude wave train in early summer a large intraseasonal variation in geopotential height over the central asia region where the asian subtropical jet is located occurs between may and june and the most dominant variation has a wave like distribution this variation in geopotential height influences precipitation across south and southeast asia in this paper we use composite analysis to determine the causes of this intraseasonal variation over central asia the wave train propagates from the northern atlantic ocean to central asia over a period of a week and generates an anomaly in geopotential height over the region the tropical disturbance which is similar to the madden julian oscillation appears a few days before the maximum of the anticyclonic anomaly over central asia and is accompanied by active convection over the indian ocean and suppressed convection over central america results of numerical experiments using a linear baroclinic model show that the active convection over the northern indian ocean causes the anticyclonic anomaly over central asia the wave train that extends from the northern atlantic ocean to central asia is generated by negative thermal forcing over central america and the phase distribution of this wave train is similar to that observed in the composite analysis central asia is the region where the effects of the tropics and middle latitudes overlap and it is an important connection point between the asian monsoon and middle latitudes

roles of synoptic to quasi biweekly disturbances in generating the summer 2003 heavy rainfall in east china abstractduring the mei yu season of the summer of 2003 the yangtze and huai river basin yhrb encountered anomalously heavy rainfall and the northern yhrb nyhrb suffered a severe flood because of five continuous extreme rainfall events a spectral analysis of daily rainfall data over yhrb reveals two dominant frequency modes one peak on day 14 and the other on day 4 i e the quasi biweekly and synoptic scale mode respectively results indicate that the two scales of disturbances contributed southwesterly and northeasterly anomalies respectively to the mei yu frontal convergence over the southern yhrb syhrb at the peak wet phase an analysis of bandpass filtered circulations shows that the lower and upper regions of the troposphere were fully coupled at the quasi biweekly scale and a lower level cyclonic anomaly over syhrb was phase locked with an anticyclonic anomaly over the philippines at the synoptic scale the strong northeasterly components of an anticyclonic anomaly with a deep cold

orographic effects of the tibetan plateau on the east asian summer monsoon an energetic perspective this paper investigates the dynamical processes through which the tibetan plateau tp influences the east asian summer monsoon easm within the framework of the moist static energy mse budget using both observations and atmospheric general circulation model agcm simulations the focus is on the most prominent feature of the easm the so called meiyu baiu mb which is characterized by a well defined southwest northeast elongated quasi stationary rainfall band spanning from eastern china to japan and into the northwestern pacific ocean between mid june and mid july observational analyses of the mse budget of the mb front indicate that horizontal advection of moist enthalpy and primarily of dry enthalpy sustains the front in a region of otherwise negative net energy input into the atmospheric column a decomposition of the horizontal dry enthalpy advection into mean transient and stationary eddy fluxes identifies the longitudinal thermal gradient due to zonal asymmetries and the meridional stationary eddy velocity as the most influential factors determining the pattern of horizontal moist enthalpy advection numerical simulations in which the tp is either retained or removed show that the tp influences the stationary enthalpy flux and hence the mb front primarily by changing the meridional stationary eddy velocity with reinforced southerly wind over the mb region and northerly wind to its north changes in the longitudinal thermal gradient are mainly confined to the near downstream of the tp with the resulting changes in zonal warm air advection having a lesser impact on the rainfall in the extended mb region

tectonic controls on the endowment of neoarchean cratons in volcanic hosted massive sulfide deposits evidence from lead and neodymium isotopes review and analysis of initial lead isotope ratios from archean volcanic hosted massive sulfide vhms and lode gold deposits and of neodymium isotopes from igneous rocks from the geologic provinces that host these deposits identifies systematic spatial and temporal patterns both within and between the provinces the abitibi wawa subprovince of the superior province is characterized by highly juvenile lead and neodymium most other archean provinces however are characterized by more evolved isotopes although domains within them can be characterized by juvenile isotope ratios the analysis indicates that the endowment measured as the quantity of metal contained in geologic resources per unit surface area of vhms and komatiite associated nickel sulfide deposits is related to the isotopic character and therefore the tectonic history of provinces that host these deposits provinces with extensive juvenile crust have significantly higher endowment of vhms deposits possibly as a consequence of higher heat flow and extension related faults provinces with evolved crust have higher endowment of komatiite associated nickel sulfide deposits possibly because such crust provided either a source of sulfur or a stable substrate for komatiite emplacement in any case initial radiogenic isotope ratios can be useful in predicting the endowment of archean terranes for vhms and komatiite associated nickel sulfide deposits limited data suggest similar relationships may hold in younger terranes lead isotope data may provide constraints on supercraton reconstructions in the archean as lead isotope systematics appear to be highly provincial similar isotope systematics between the superior province and the eastern goldfields superterrane may indicate a linkage during the neoarchean consistent with the similar geologic and metallogenic histories of these provinces

intraseasonal teleconnection between north american and western north pacific monsoons with 20 day time scale abstract based on a recently released high resolution reanalysis dataset for the north american region the intraseasonal variability isv with a time scale of about 20 days of the north american monsoon nam is examined the rainfall signals associated with this phenomenon first emerge near the gulf of mexico and eastern pacific at about 20 n they subsequently migrate to the southwestern united states along the slope of the sierra madre occidental the rainfall quickly dissipates upon arrival at the desert region of arizona and new mexico aznm the enhanced rainfall over aznm is accompanied by strong southeasterly low level flow along the gulf of california this pattern bears strong resemblance to the circulation related to gulf surge events as documented by many studies the southeasterly flow is associated with an anomalous low vortex over the subtropical eastern pacific ocean off california and a midlatitude anticyclone over the central united states in the lower troposphere this flow pat

a hypothesis for the origin of perylene based on its low abundance in sediments of green bay wisconsin abstract perylene a polycyclic aromatic hydrocarbon pah that is common in sediments is believed to originate principally from anaerobic diagenesis of organic matter but its precursor material remains enigmatic we have investigated the formation of perylene in a dated sediment core from green bay wi comparisons of sedimentary profiles of perylene anthropogenic pahs land plant derived hydrocarbons and aquatic contributions of organic matter rule out a specific industrial terrigenous or aquatic precursor for perylene instead perylene seems to be formed from any kind of organic matter as a consequence of a specific type of microbial activity in sub bottom sediments despite an abundance of organic matter the amount of perylene is low in green bay and in other organic carbon rich lake sediments the abundant availability of organic matter that stimulates microbial activity in green bay sediments would seem to favor perylene formation in such sediments we therefore hypothesize that the microorganisms responsible for perylene formation do not compete successfully with those that flourish in sediments rich in organic matter perylene formation consequently does not become significant until deeper in sediments after the more reactive types of organic matter have been consumed

new insights into archean crustal development from geochronology in the rainy lake area superior province canada precise isotopic analyses of zircon titanite and rutile from units in the rainy lake area of northwest ontario are combined with structural investigations to develop new stratigraphic interpretations in which lithotectonic sequences were juxtaposed by thrusting prior to steepening by wrenching ages for the oldest volcanic and plutonic rocks in the area range from 2725 pm 2 ma to 2728 4 3 ma the age of metagray wackes of the coutchiching group is bracketed between 2704 pm 3 ma and 2692 pm 2 ma by detrital zircon and a crosscutting intrusion alluvial conglomerate of the seine group is bracketed between 2696 5 3 ma the age of a clast and 2686 2 1 ma the age of the undeformed ottertail lake pluton the coutchiching group is younger than structurally overlying metavolcanic rocks and is therefore allochthon ous these data suggest that sedimentation and deformation were controlled by collisional plate interactions and subsequent transpression at the subprovince boundary combined with dat

distinct quasi biweekly features of the subtropical east asian monsoon during early and late summers using global precipitation climatology project daily rainfall and era interim reanalysis data we investigate the distinct characteristic of quasi biweekly variation qbv 12 20 days over east asia ea during early june 10 july 20 and late july 21 august 31 summer the qbv maximum variance is found over the core region of ea 30 40 n 110 130 e which includes eastern china lower reaches of the yellow huaihe and yangtze rivers and the korean peninsula at both its peak wet and dry phases qbv over the core region has a baroclinic structure but with different spatial distributions different lower level prevalent wind anomalies and different upper level major circulation anomalies in the two subseasons meanwhile the two subseasons have different propagating tracks prior to reaching the peak phase and different precursors associated with the local genesis of qbv furthermore during the transition from the peak dry to peak wet phase of qbv the major monsoon circulations have different behaviors that tropical monsoon trough extends eastward in early summer but retreats westward in late summer and the south asia high sah and western north pacific wnp subtropical high move toward away from each other in early late summer the abrupt change of mean state in mid to late july which includes the northward migration of westerly jet sah and wnp and the weakening and broken of westerly jet is considered the root cause of the change in behavior of qbv finally we indicate that the tropical monsoon trough and midlatitude westerly jet are possible sources of qbv over subtropical ea in both subseasons and provide useful guidance for 2 3 week predictions over ea

two interannual dominant modes of the south asian high in may and their linkage to the tropical sst anomalies the variations of the intensity and position of the south asian high sah in may are critical for the interannual change in the asian summer monsoon onset process the present work has defined two dominant modes of the sah in may via the principal component analysis of sah s strength zonal extension and ridgeline position indices during 1979 2015 the first mode sah intensity mode features a coherent enhancement of the sah strength and zonal extension while the second mode sah position mode exhibits a meridional swing of the sah ridgeline both diagnosis analysis and numerical experiments validate that the distinct evolution of enso in boreal spring determines its different influences on the two modes when an el nino decays quickly during march may its resultant warm anomalies of sea surface temperature sst in the tropical indian ocean can affect the sah intensity mode by modifying the tropical convection over the southwestern bay of bengal acting as a local sst forcing to the circulation however the sah position mode depends on the persistence of the enso event during boreal spring the remote el nino related sst forcing can enhance the large scale descent over the indo pacific ocean which suppresses the tropical convection to modify the mid upper level thermal structure over south asia inducing the interannual variation of the sah ridgeline in may

impact of the quasi biweekly oscillation over the western north pacific on east asian subtropical monsoon during early summer 1 the impact of quasi biweekly oscillation qbwo over the western north pacific on east asian summer monsoon easm is investigated the life cycle of qbwo is divided into eight phases defined by the two leading principal components pc1 and pc2 of an empirical orthogonal function analysis subtropical rainfall shows significant changes with a northwestward propagation of convection from equatorial regions to the south china sea scs the most significant variations occur in qbwo phases 3 and 4 enhanced convection over scs and phases 7 and 8 reduced convection over scs the east asia mei yu significantly decreases in qbwo phases 3 and 4 but increases in phases 7 and 8 the qbwo influences easm through modulating the subtropical monsoon flow and extratropical circulation the response of lower tropospheric atmosphere to qbwo shows a northwestward propagation and a downstream wave train that extends northward into the western north pacific modulating the scs monsoon trough and the easm flow associated with moisture transportation the mid tropospheric extratropical circulation and the western pacific subtropical high also show obvious changes accompanying qbwo evolution resulting in circulation patterns associated with cold air activity moreover changes with qbwo are found in the upper tropospheric east asian westerly jet stream and the south asian high and these changes contribute to upper level divergence over subtropical east asia

a possible terrigenous origin for perylene based on a sedimentary record of a pond lorraine france abstract the origin of perylene a five ring polycyclic aromatic hydrocarbon pah in sediments has been a matter of constant debate and its formation mechanisms remain unclear a perylene record in sediment was described and could support a clear link between perylene and terrigenous organic matter om input the distributions of pahs the variations of organic proxies such as the ratio of terrigenous to aquatic n alkanes tar hc and 5 h stanols 5 sterols ratio in sediments have been investigated sediments were sampled from a pond artificially created during the middle ages from a swampy area in the period prior to the pond creation for which high contributions of terrigenous om were evidenced perylene was found to be the predominant pah furthermore perylene content was shown to increase in response to the establishment of more reducing conditions this result supports the common idea that the main source of perylene is natural and derives from biogenic precursors under reducing conditions the creation of the pond in this wetland is marked by the deposition of a wood rich level characterized both by more oxygenated conditions and higher concentrations of perylene these high concentrations could result from the introduction of high concentrations of biogenic precursors of perylene under oxidative conditions subsequently the progressive burial of the woody level could have allowed the establishment of oxygen depleted conditions and the formation of perylene these results validate the use of perylene as a paleoenvironmental marker of terrigenous sources but it must be carefully used as a marker for syn or post depositional oxygen depleted conditions in lacustrine environments

three dimensional distribution of igneous rocks near the pebble porphyry cu au mo deposit in southwestern alaska constraints from regional scale aeromagnetic data abstractaeromagnetic data helped us to understand the 3d distribution of plutonic rocks near the pebble porphyry copper deposit in southwestern alaska usa magnetic susceptibility measurements showed that rocks in the pebble district are more magnetic than rocks of comparable compositions in the pike creek stuyahok hills volcano plutonic complex the reduced to pole transformation of the aeromagnetic data demonstrated that the older rocks in the pebble district produce strong magnetic anomaly highs the tilt derivative transformation highlighted northeast trending lineaments attributed to tertiary volcanic rocks multiscale edge detection delineated near surface magnetic sources that are mostly outward dipping and coalesce at depth in the pebble district the total horizontal gradient of the 10 km upward continued magnetic data showed an oval deep magnetic contact along which porphyry deposits occur forward and inverse magnetic modeling showed that the magnetic rocks in the pebble district extend to de

crustal lineament control on magmatism and mineralization in northwestern argentina geological geophysical and remote sensing evidence abstract the relationship between long lived deep crustal lineaments and the locations of magmatic centers and associated mineral deposits has been investigated in the puna region of northwestern argentina through the analysis of regional aeromagnetic surveys landsat images and geological information the good exposure and excellent preservation of basement and supracrustal geology in this region makes it particularly suitable for such a study at a regional scale several contrasting magnetic domains are recognized which correlate with crustal geology two basement domains are separated by a nne trending boundary which is believed to correlate with a paleozoic suture zone between the pampia to the southeast and arequipa antofalla terranes to the northwest locally overlying these basement terranes is the cenozoic magmatic domain which is best developed in the n s trending volcanic arc at the western edge of the puna the cordillera occidental in addition four southeast trending volcanic zones extend for several hundred kilometers across the puna many important mineral deposits and areas of hydrothermal alteration are associated with these volcanic breakouts and we have selected three such areas for more detailed study bajo de la alumbrera argentina s largest porphyry copper deposit cerro galan the largest ignimbrite caldera in argentina with associated hydrothermal alteration zones and el queva a historic polymetallic district located within a major volcanic range a comparison of lineament maps generated from aeromagnetic and landsat tm images reveals broad correlation between these different remote sensing techniques which respectively highlight subsurface magnetic and surface geological features in addition the locations of magmatic and hydrothermal centers can be related to the interpreted structural framework and are seen to occur near the intersections of major lineament zones it is suggested that in three dimensions such intersection zones form trans lithospheric columns of low strength and high permeability during transpressional or transtensional tectonic strain and may thereby serve as conduits for magma ascent to the shallow crust pooling of large volumes of deeply derived magma in shallow crustal magma chambers may then result in voluminous devolatilization and the formation of hydrothermal mineral deposits it is important to note that in this model structural intersections serve as facilitators for magma ascent and volatile exsolution but do not in themselves cause this process other factors such as magma supply rate and tectonic stress are essential primary ingredients and local magmatic and volcanic processes affect the ultimate potential for ore formation nevertheless we suggest that lineament analysis provides a valuable framework for guiding the early stages of mineral exploration other regional and local geological considerations must then be applied to identify priority targets within this framework

assessment of the relationship between emplacement of the algoman plutons and regional deformation in the rainy lake region ontario the algoman suite of granites and granodiorites located within the rainy lake region of the superior province intruded the wabigoon quetico subprovince boundary about 2686 ma deformation occurred during the late archean collision between the wabigoon and wawa volcanic arcs the algoman plutons are the youngest rocks in the region their apparent lack of macroscopic deformation fabrics has led previous researchers to use their age as a constraint for the cessation of regional deformation however contrasting competence between the relatively rigid granites and surrounding volcanic and metasedimentary rocks suggests that obvious deformation fabrics may not be observed in the plutons even if they were present during deformation a field anisotropy of magnetic susceptibility ams gravity inversion model and microstructural study were undertaken on two neighboring algoman plutons to determine their emplacement history relative to the regional deformation there is a steep macroscopic foliation in the adjacent rocks and in parts of the plutons the magnetic foliation is very strong and roughly coincident with the field foliations the gravity inversion models indicate that the plutons are relatively shallow 1 km and 4 5 km at their deepest points and their shapes are consistent with emplacement during dextral transpression quartz microstructures such as undulose extinction and subgrain formation indicate that there was some solid state deformation accommodated by dislocation creep mechanisms the field ams gravity and microstructural evidence indicate that the plutons were most likely emplaced syntectonically thus the pluton age does not provide a conclusive constraint to the cessation of regional deformation

blocking highs over asia and monsoon droughts over india severe summer droughts of the indian subcontinent have been found to accompany prolonged breaks in the south west monsoon data from the years of severe drought suggest that the associated breaks were due to upper tropospheric blocking ridges over east asia we present here a model for the evolution of two such blocking ridges the east asia eabr and the west asia wabr apparently an intense wabr the initiator of the monsoon break precedes the formation of the eabr this cycle could be a way of predicting years of intense drought or monsoon activity

composite synvolcanic intrusions associated with precambrian vms related hydrothermal systems large subvolcanic intrusions are recognized within most precambrian vms camps of these 80 are quartz diorite tonalite trondhjemite composite intrusions the vms camps spatially associated with composite intrusions account for 90 of the aggregate sulfide tonnage of all the precambrian intrusion related vms camps these low alumina low k and high na composite intrusions contain early phases of quartz diorite and tonalite followed by more voluminous trondhjemite they have a high proportion of high silica 74 sio2 trondhjemite which is compositionally similar to the vms hosting rhyolites within the volcanic host rock successions the quartz diorite and possibly tonalite phases follow tholeiitic fractionation trends whereas the trondhjemites fall within the composition field for primitive crustal melts these transitional m i type primitive intrusive suites are associated with extensional regimes within oceanic arc environments subvolcanic composite intrusions related to the archean sturgeon lake and noranda and paleoproterozoic snow lake vms camps range in volume from 300 to 1 000 km3 three have a sill morphology with strike lengths between 15 and 22 km and an average thickness between 1 500 and 2 000 m the fourth has a gross stock like shape the vms deposits are principally restricted to the volcanic strata above the strike length of the intrusions as are areally extensive thin exhalite units the composite intrusions contain numerous internal phases which are commonly clustered within certain parts of the composite intrusion these clusters underlie eruptive centers surrounded by areas of hydrothermal alteration and which contain most of the vms deposits early quartz diorite and tonalite phases appear to have intruded in rapid succession evidence includes gradational contacts magma mixing and disequilibrium textures they appear to have been emplaced as sill dike swarms these early phases are present as pendants and xenoliths within later trondhjemite phases the trondhjemite phases contain numerous internal contacts indicating emplacement as composite sills common structural features of the composite intrusions include early xenolith phases abundant small comagmatic dikes fractures and veins and in places columnar jointing internal phases may differ greatly in texture from fine to coarse grained aphyric and granophyric through seriate to porphyritic mineralogical and isotopic evidence indicates that early phases of each composite intrusion are affected by pervasive to fracture controlled high temperature 350 450 c alteration reflecting seawater rock interaction trondhjemite phases contain hydrothermal magmatic alteration assemblages within miarolitic cavities hydrothermal breccias and veins this hydrothermal magmatic alteration may in part be inherited from previously altered wall rocks two of the four intrusions are host to cu mo rich intrusive breccias and porphyry type mineralization which formed as much as 14 ma after the main subvolcanic magmatic activity the recognition of these precambrian subvolcanic composite intrusions is important for greenfields vms exploration as they define the location of thermal corridors within extensional oceanic arc regimes which have the greatest potential for significant vms mineralization the vms mineralization may occur for 2 000 m above the intrusions in some cases vms mineralization has been truncated or enveloped by late trondhjemite phases of the composite intrusions evidence that much of the trondhjemitic magmatism postdates the principal vms activity is a critical factor when developing heat and fluid flow models for these subseafloor magmatic hydrothermal systems

teleconnections associated with northern hemisphere summer monsoon intraseasonal oscillation the boreal summer intraseasonal oscillation bsiso has strong convective activity centers in indian i western north pacific wnp and north american na summer monsoon sm regions the present study attempts to reveal bsiso teleconnection patterns associated with these dominant intraseasonal variability centers during the active phase of ism a zonally elongated band of enhanced convection extends from india via the bay of bengal and philippine sea to tropical central pacific with suppressed convection over the eastern pacific near mexico the corresponding extratropical circulation anomalies occur along the waveguides generated by the north african asian jet and north atlantic north european jet when the tropical convection strengthens over the wnpsm sector a distinct great circle like rossby wave train emanates from the wnp to the western coast of united states us with an eastward shift of enhanced meridional circulation in the active phase of nasm large anticyclonic anomalies anchor over the western coast of us and eastern canada and the global teleconnection pattern is similar to that during a break phase of the ism examination of the evolution of the bsiso teleconnection reveals quasi stationary patterns with preferred centers of teleconnection located at europe russia central asia east asia western us and eastern us and canada respectively most centers are embedded in the waveguide along the westerly jet stream but the centers at europe and russia occur to the north of the jet induced waveguide eastward propagation of the iso teleconnection is evident over the pacific north america sector the rainfall anomalies over the elongated band near the monsoon domain over the indo western pacific sector have an opposite tendency with that over the central and southern china mexico and southern us providing a source of intraseasonal predictability to extratropical regions the bsiso teleconnection along and to the north of the subtropical jet provides a good indication of the surface sir temperature anomalies in the nh extratropics

quasi biweekly impact of the atmospheric heat source over the tibetan plateau on summer rainfall in eastern china we investigated the intraseasonal relationship between the atmospheric heat source over tibetan plateau tp and summer rainfall in eastern china a quasi biweekly oscillation qbwo is the common dominant periodicity over both the tp and eastern china crucially the tp heat source qbwo leads rainfall qbwo over its downstream region by 2 8 days the qbwo over the tp shows a significant eastward propagation phase composite further identified the specific propagation pathway tp qbwo first propagates eastward to central china southward to southern china and then northeastward to the lower reaches of the yangtze river with a zigzag propagating pathway mechanistically the eastward propagation of the upper level divergence caused by the movement of the 200 hpa jet core and south asian high contributes to the eastward propagation of the rainfall qbwo simultaneously the eastward westward shift in the western north pacific subtropical high causes deepening flattening of the monsoon trough and the occurrence of an anomalous cyclone anticyclone over the western north pacific an anomalous anticyclonic cyclonic circulation around the tp appears with the wet to dry dry to wet phase transition of the tp qbwo together they play a crucial part in the southward northeastward movement of the qbwo further dynamic analysis indicates that the horizontal moisture advection acts on the whole eastward propagating process of the qbwo whereas the horizontal vorticity advection is only significant when qbwo is over the tp this study shows that the fluctuations in tp heat source are important indicators in extended forecasts of summer rainfall in eastern china

evidence for a battle mountain eureka crustal fault zone north central nevada and its relation to neoproterozoic early paleozoic continental breakup 1 combined evidence from gravity radiogenic isotope and magnetotelluric mt data indicates a crustal fault zone that coincides with the northwest trending battle mountain eureka bme mineral trend in north central nevada usa the bme crustal fault zone likely originated during neoproterozoic early paleozoic rifting of the continent and had a large influence on subsequent tectonic events such as emplacement of allochthons and episodic deformation magmatism and mineralization throughout the phanerozoic mt models show the fault zone is about 10 km wide 130 km long and extends from 1 to 5 km below the surface to deep crustal levels isotope data and gravity models imply the fault zone separates crust of fundamentally different character geophysical evidence for such a long lived structure likely inherited from continental breakup defies conventional wisdom that structures this old have been destroyed by cenozoic extensional processes moreover the coincidence with the alignment of mineral deposits supports the assertion by many economic geologists that these alignments are indicators of buried regional structures

the origin and dispersion characteristics of the observed tropical summertime synoptic scale waves over the western pacific abstract the origin initiation and dispersion behavior of the observed summertime synoptic scale disturbances in the tropical western pacific are studied these westward propagating disturbances have the strongest growth rate over the region of 130 160 e off the equator the three dimensional wave activity flux associated with a wave packet in the vicinity of this region is computed in general wave activity is directed westward there is accumulation of activity flux which gives rise to the amplification of waves in the low levels such accumulation can be attributed to the convergence of both the mean flow and the intrinsic group velocity diabatic forcing also contributes to the growth of disturbances and is most important in the 500 600 hpa layer along the east west oriented storm tracks of the synoptic scale disturbances there are two different dynamical regimes west of 150 e enhanced convection is associated with increased specific humidity at the top of the planetary boundary layer an

geochronology of wabigoon belt granitoids northwestern ontario rb sr isochrons for seven late tectonic plutons whole rock rb sr isochrons are presented for seven late tectonic granitoid plutons intruded into supracrustal rocks of the wabigoon volcanic plutonic belt age estimates range from 2461 78 ma ottertail lake stock to 2645 158 ma bears passage stock a mean age estimate by weighted pooling of the isochrons gives 2555 41 ma while pooling 39 samples into one regression gives 2568 35 ma these ages concur with estimates for the duration of the kenoran orogeny error limits on our isochrons incorporate the duration of polydiapirism aplitic dyking and deuteric metasomatism available ages indicate that syntectonic and late tectonic granitoid plutonism spanned a geologically short time interval centered at 2565 62 ma that cannot be differentiated by the rb sr technique consistently low initial sr ratios of 0 7008 0 0006 indicate a mantle or low rb sr source

a simple and convenient determination of perylene preserved in the late neogene wood from northeastern tennessee using fluorescence spectroscopy abstract a new and convenient fluorescence spectroscopic method has been developed for the separation and determination of perylene in fossil wood recovered from a late miocene to early pliocene gray fossil site in tennessee usa this is the first report where perylene was separated from fossil samples from this newly discovered fossil site the chemical structure of perylene was elucidated and confirmed by uv visible and 1h nmr spectroscopies and esi tof high accuracy mass spectrometry the fluorescence of perylene was used to measure the contents of perylene in the fossil conifer and oak wood which were found to be 5 34 and 0 78 g g respectively the results suggested that the amount of perylene in the fossil conifer wood was 7 fold higher than that in the oak wood the method which uses highly sensitive fluorescence spectroscopy should provide a new approach for the analysis of other fossil and geochemical samples containing perylene

an observational study of the south china sea monsoon during the 1979 summer onset and life cycle abstract the onset and life cycle of the 1979 south china sea summer monsoon were examined in the context of the 30 60 and 12 24 day monsoon modes the former intraseasonal mode formed the northward migrating monsoon trough ridge while the latter intraseasonal mode propagated westward in the south china sea the monsoon in this region exhibited three cycles over the summer may august with the onset taking place about one cycle ahead of the onset of the indian and japanese monsoons climatologically a summer trough line radiated out from the indian monsoon trough region across indochina to the northern south china sea the monsoon onset occurred when the 30 60 day monsoon trough and the 12 24 day low center arrived simultaneously at the northern south china sea close to the climatological summer trough line in the middle of may the breaks occurred when the 30 60 day monsoon ridge lines and the 12 24 day high center met near 15 20 n in the northern south china sea the south china sea monsoon wa

characteristics and mechanisms of the subseasonal eastward extension of the south asian high abstractthis study investigates the features of eastward extension of the south asian high sah and its connection with diabatic heating and rainfall over eastern asia on subseasonal time scales the causes of sah s eastward extension are examined by potential vorticity pv diagnosis with emphasis on the joint role of diabatic heating feedback and midlatitude wave train the sah s eastward extension features eastward propagation of a wave train across eurasia among the wave train the migration of weak high from the western flank of the tibetan plateau tp to the east of tp contributes to the sah s eastward extension at the early stage when the sah approaches its easternmost position a strong negative pv positive geopotential height center prevails to the east of the tp at 200 hpa the associated anomalies in diabatic heating and rainfall include the anomalous heating and above normal rainfall over the south china sea scs and subtropical western pacific occurring 12 days before the sah s eastern

geochemistry nd pb and sr isotope systematics and u pb zircon ages of the neoarchean bad vermilion lake greenstone belt and spatially associated granitic rocks western superior province canada abstract the ca 2720 ma neoarchean bad vermilion lake bvl greenstone belt in the western superior province canada is composed of a suite of tholeiitic to calc alkaline basalts to rhyolites volcaniclastic rocks gabbros and timiskaming type siliciclastic sedimentary rocks the greenstone belt was intruded by neoarchean granitic rocks and underwent greenschist facies metamorphism and intense deformation resulting in mobilization of many elements e g rb ba sr k u pb the high field strength element and rare earth element systematics of the volcanic and volcaniclastic rocks and gabbros are consistent with subduction zone geochemical signatures suggesting that the bvl greenstone belt formed in a magmatic arc setting on the basis of lithological associations and trace element systematics the bvl greenstone belt is defined as a fragment of a neoarchean subduction related ophiolite three rhyolite samples from the belt have yielded 2722 18 ma 2706 13 ma and 2710 28 ma u pb zircon ages representing the approximate age of the arc volcanism in the study area and development of a subduction zone between the western wabigoon terrane to the north and the wawa abitibi terrane to the south the intrusion of the ca 2664 15 ma late to post tectonic potassic ottertail lake granite marks the end of tectonic accretion in the study area both the volcanic rocks and gabbros display large ranges of nd 143 nd 144 nd 0 511600 0 512849 e nd 2720 ma 0 8 to 4 0 pb 206 pb 204 pb 13 80 60 67 and sr 87 sr 86 sr 0 701481 1 01154 isotopic compositions suggesting that these isotope systems were variably affected by post magmatic element mobility neither the sm nd 2921 200 ma nor rb sr 2130 610 ma system has yielded reliable regression isochron ages reflecting the open system behavior of these systems during metamorphism despite large uncertainties pb pb regression ages yielded by all rock types 2661 60 ma and basalts and gabbros 2725 83 ma agree with the zircon u pb ages of the rhyolites suggesting that the u pb system was the most robust among all three systems

the formation mechanism of the bonin high in august the bonin high is a subtropical anticyclone that is predominant near japan in the summer this anticyclone is associated with an equivalent barotropic structure often extending throughout the entire troposphere although the equivalent barotropic structure of the bonin high has been known for years among synopticians because of its importance to the summer climate in east asia there are few dynamical explanations for such a structure the present paper attempts to provide a formation mechanism for the deep ridge near japan we propose a new hypothesis that this equivalent barotropic ridge near japan is formed as a result of the propagation of stationary rossby waves along the asian jet in the upper troposphere the silk road pattern first the monthly mean climatology is examined in order to demonstrate this hypothesis it is shown that the enhanced asian jet in august is favourable for the propagation of stationary rossby waves and that the regions of descent over the eastern mediterranean sea and the aral sea act as two major wave sources second a primitive equation model is used to simulate the climatology of august the model successfully simulates the bonin high with an equivalent barotropic structure the upper tropospheric ridge is found to be enhanced by a height anomaly of more than 80 m at 200 hpa when a wave packet arrives sensitivity experiments are conducted to show that the removal of the diabatic cooling over the asian jet suppresses the silk road pattern and formation of an equivalent barotropic ridge near japan while the removal of the diabatic heating in the western pacific does not copyright 2003 royal meteorological society

connection between anomalous zonal activities of the south asian high and eurasian summer climate anomalies abstractusing the daily mean anomalies of atmospheric variables from the ncep reanalysis 1 ncep r1 this study reveals the connection between anomalous zonal activities of the south asian high sah and eurasian climate anomalies in boreal summer an analysis of variance identifies two major domains with larger geopotential height variability located in the eastern and western flanks of the sah at around 100 and 150 hpa respectively for both eastern and western domains extreme events are selected during 1981 2014 when normalized height anomalies are greater than 1 0 less than 1 0 standard deviation for at least 10 consecutive days based on these events four sah modes that include strong and weak tibetan modes stm and wtm respectively and strong and weak iranian modes sim and wim respectively are defined to depict the zonal sah features the positive composite in the eastern western domain indicates the stm sim manifests a robust wavelike pattern with an anomalous low at 150 hpa and su

distribution of orogenic gold deposits in relation to fault zones and gravity gradients targeting tools applied to the eastern goldfields yilgarn craton western australia a quantitative spatial analysis of mineral deposit distributions in relation to their proximity to a variety of structural elements is used to define parameters that can influence metal endowment deposit location and the resource potential of a region using orogenic gold deposits as an example geostatistical techniques are applied in a geographic information systems based regional scale analysis in the high data density yilgarn craton of western australia metal endowment gold production and gold rank per square kilometer is measured in incremental buffer regions created in relation to vector lines such as faults the greatest metal tonnages are related to intersections of major faults with regional anticlines and to fault jogs particularly those of dilatant geometry using fault length in parameter search there is a strong association between crustal scale shear zones faults and deposits nonetheless it is the small scale faults that are marginal or peripheral to the larger scale features that are more prospective gravity gradients depicted as multiscale edges or gravity worms show a clear association to faults that host gold deposits long wavelength long strikelength edges interpreted as dominantly fault related have greater metal endowment and provide a first order area selection filter for exploration particularly in areas of poor exposure statistical analysis of fault fold and gravity gradient patterns mainly affirms empirical exploration criteria for orogenic gold deposits such as associations with crustal scale faults anticlinal hinge zones dilational jogs elevated fault roughness strong rheological contrasts and medium metamorphic grade rocks the presence and concurrence of these parameters determine the metallogenic endowment of a given fault system and segments within the system by quantifying such parameters the search area for exploration can be significantly reduced by an order of magnitude while increasing the chance of discovery

quasi biweekly oscillation over the tibetan plateau and its link with the asian summer monsoon abstract intraseasonal variation isv is especially prominent and unique in the asian summer monsoon region in this work the dominant isv mode over the tibetan plateau tp in the summer monsoon season june august together with its structure and evolution is identified using station observations global precipitation climatology project precipitation data and era interim during 1979 2011 results indicate that quasi biweekly oscillation qbwo is the dominant mode of isv over the tp and is significant in terms of the circulation precipitation and diabatic heating fields in particular the qbwo is closely related to the onset and active break phases of the tp summer monsoon in most cases the qbwo originates from the equatorial western pacific and first propagates northwestward to the bay of bengal and northern india then northward to the southeastern tp and finally eastward to the east asian area showing a clockwise propagation pathway two main mechanisms are responsible for the northward

perylene an indicator of alteration processes or precursor materials abstract perylene is a polycyclic aromatic hydrocarbon pah that is found pervasively in both marine and freshwater sediments yet its origin remains obscure we have explored relationships between perylene and possible precursor materials in two 210 pb dated sediment cores from lake ontario in which contributions of aquatic and land plant organic matter and concentrations of anthropogenic pahs have been measured no significant correlations were identified between perylene occurrence and indicators of terrigenous or aquatic sources of organic matter distinct differences between perylene and anthropogenic pah sedimentary profiles rule out an industrial source for perylene at these locations the general pattern of low to absent perylene concentrations in upper oxic sediments and increasing concentrations with depth indicates that in situ diagenesis under anoxic conditions produces perylene and that its formation is kinetically controlled the results of our study suggest that perylene is formed from non specific precursor materials by biotic or abiotic transformation processes if this scenario accurately describes its formation then perylene is an indicator of depositional conditions rather than the source of organic matter

emplacement and deformation features of syntectonic leucocratic veins from rainy lake zone western superior province canada abstract networks of leucocratic veins are widespread in the rice bay redgut bay domain of the rainy lake zone at the wabigoon quetico subprovince boundary archean superior province canada vein geometries and their cross cutting relationships with host rocks are indicative of syntectonic emplacement within a regional late archean transpressional deformation event kenoran orogeny the relative folding and boudinage of the veins compared to their host rocks indicate that they were emplaced syntectonically with the d2 deformation semi quantitative strain and vorticity analyses confirm the syn d2 timing of the veins the observed structural features are interpreted as being formed during magma emplacement along dilatant fractures and subsequent solid state deformation under overall ductile deformation conditions the structures related to emplacement are better preserved in domains of low post emplacement strain and veins intruded into competent host rocks whereas the folds and boudins related to post emplacement deformation are well developed in veins intruded into relatively incompetent host rocks in domains of high strain the primary intrusive structures are modified or even locally obliterated due to increasing deformation it is envisaged that regional kinematics and the rheological state of host rocks are the main controls on the style of vein emplacement and deformation the variety of observed structures is considered the result of deformation and lithological heterogeneity rather than several distinct magmatic events

time transgressive archean unconformities underlying molasse basin fill successions of dissected oceanic arcs superior province canada abstract late archean diachronous unconformities underlying tectonically controlled coarse clastic successions are located throughout the superior province of canada examples studied in detail include hiatuses at the base of the timmins and kirkland basins in the abitibi greenstone belt and the crowduck and stormy basins in the wabigoon subprovince the timmins molasse basin fill succession overlies a high angle subaerial unconformity separating deepwater turbiditic deposits from fluvial conglomerates a subaerial erosional unconformity defines the contact between mafic flows and overlying felsic volcaniclastic deposits and fluvial conglomerates of the kirkland basin the crowduck and stormy successions are characterized by shallow water and subaerial unconformities between quartz feldspar porphyry stocks and clastic deposits the pronounced characteristics of the molasse basins which include 1 basal unconformities with older sedimentary volcanic or plutonic rocks 2 bounding fault systems 3 ba

latest miocene to earliest pliocene sedimentation and climate record derived from paleosinkhole fill deposits gray fossil site northeastern tennessee u s a abstract lacustrine sediments deposited within a paleosinkhole at the gray fossil site gfs in northeastern tennessee usa provide a latest miocene and earliest pliocene 4 5 7 ma record of sedimentation and paleoclimate the basal graded facies consists of mm to cm thick normally graded layers of primarily locally derived terrigenous silts and fine sands with low organic content which record storm flow influxes into a 40 m deep paleosinkhole lake the graded facies is overlain by the laminated facies which is characterized by mm thick non graded a b couplets of abundant macerated terrestrial organic matter and fine to coarse quartz sand a alternating with quartz and carbonate silt b isotopic evidence for establishment of either c4 dominated or mixed c3 c4 terrestrial ecosystems is not evident at this site 13 c values of bulk organic matter from the basal graded facies range from 24 to 26 pdb and decrease upsection to 28 to 30 in the organic rich laminated facies isotope values covary with changes in both total organic content toc 0 25 1 wt in graded facies 2 12 wt in laminated facies and in carbon nitrogen ratio c n 1 2 in graded facies 20 50 in laminated facies these upsection changes in sedimentary facies and organic geochemistry within the gfs are attributed to either 1 a climate shift characterized by increased precipitation and concomitant increased vegetation within the paleosinkhole watershed over time or 2 progressive shallowing and eutrophication of the paleosinkhole lake coupled with organic diagenesis within either the watershed or the paleosinkhole sediments in which there was isotopic discrimination associated with organic matter decomposition subaerial exposure of the paleosinkhole lake is recorded by paleosol development

role of the tibetan plateau thermal forcing in the summer climate patterns over subtropical asia the mechanism of the tibetan plateau tp thermal forcing in influencing the summer climate patterns over subtropical asia is investigated by means of ncep ncar reanalysis diagnosis results show that since the tp is a huge elevated heating source with the strongest heating in the surface layers in summer the thermal adaptation results in a shallow cyclonic circulation near the surface and a deep anticyclonic circulation above it according to the steady barotropic vorticity equation for large scales airflow must converge in the lower layers and diverge in the higher layers over the eastern side of the tp however the western side of the tp is characterized by a reversed structure i e divergence in lower layers but convergence in higher layers hence pumping and sucking processes bring in upward and downward movement over the east and west sides of the tp respectively such a circulation is embedded in the large scale circulation that is forced by the eurasian continental heating because the tp together with iran plateau are located at the central and eastern parts of the continent and because the orography induced circulation is in phase with the continental scale circulation the role of the tp thermal forcing is to intensify the east asian monsoon to its east and the dry and hot desert climate in mid asia to its west the summertime thermal forcing of the rockies and andes can generate similar circulations along the two subtopics as the tp does since they are located near the western coasts but the lower troposphere poleward flow that is induced by orographic thermal forcing does not coincide with the poleward flows over the eastern coastal region that is induced by continental heating and the monsoon rainfall in north and south america is not as strong as in east asia however the equatorward flow and the associated subsidence induced by the two mountain ranges along the western coasts of both north and south america are in phase with those induced by continental heating these contribute to the formation of the stable low stratus clouds and strong long wave radiative cooling over the eastern subtropical pacific regions just off the western coast of the continent

biomarker and stable carbon isotope systematics of fossil wood from the second lusatian lignite seam of the lubstow deposit poland abstract decay of fossil wood gelification collected from the middle miocene 2nd lusatian lignite seam at the lubstow open cast mine poland is characterised by its maceral variety fluorescence intensity and cellulose content cellulose decomposition leads to lower molar h c ratio values of the organic matter as indicated by higher total organic carbon toc content of samples characterised by low cellulose content biochemical formation of hydrocarbons in the wood due to enhanced microbial activity is evidenced by higher hydrocarbon content in the extracts higher relative proportions of n alkanes and hopanoids are observed in the hydrocarbon fractions of wood remains characterised by low cellulose yield the results provide evidence for the formation of these compounds during biogeochemical transformation of organic matter hopanoid contents are considered to reflect the activity of aerobic bacteria and or fungi because of enhanced perylene content in the hydrocarbon fractions from gelified wood samples fungi are considered as the major precursor carriers of this polycyclic aromatic hydrocarbon the results provide evidence that biomarker composition of fossil wood can be used to trace biochemical transformation processes chemotaxonomical classification of fossil wood fragments as gymnosperms most probably species of the coniferales families taxodiaceae cupressaceae are based on the molecular composition of terpenoid hydrocarbons and a mean 13 c value of 24 5 depletion of gelified samples in 13 c as compared to ungelified wood is caused by the effect of progressive decomposition of cellulose the data indicate that cellulose 13 c data mean 13 c 20 8 are also affected by wood decomposition and so only samples with comparable cellulose content should be used for the reconstruction of environmental changes inter species as well as intra plant variation in carbon isotope differences and of decay resistance between cellulose and lignin have to be taken into account

active break cycles diagnosis of the intraseasonal variability of the asian summer monsoon in this study various diagnostics have been applied to daily observed outgoing longwave radiation olr and ecmwf reanalysis era products to provide a comprehensive description of the active break cycles associated with the asian summer monsoon and to address the differing behaviour of the two dominant time scales of intraseasonal variability 10 20 days and 30 60 days composite analysis of olr based on filtered daily all india rainfall air for the 40 day 30 60 days intraseasonal mode indicates that during active phases convection is significantly enhanced over the indian continent extending over the bay of bengal maritime continent and equatorial west pacific while convection is suppressed over the equatorial indian ocean and northwest tropical pacific resulting in a quadrapole structure over the asian monsoon domain in response to this heating pattern the large scale hadley lateral and the two east west transverse tropical circulations are enhanced there is also a significant impact on the extra tropical circulation through excitation and propagation of rossby waves in contrast the 15 day mode is more regional to the monsoon domain and has a prominent east west orientation in convection only the local hadley circulation over the monsoon region is modulated by this mode the evolution of these two modes as revealed by pop principal oscillation pattern analysis shows that the 40 day mode originates over the equatorial indian ocean once formed it has poleward propagation on either side of the equator and eastward propagation into the equatorial west pacific from the equatorial west pacific northward propagation over the west pacific and westward propagation into the indian longitudes are prominent the propagative features are complex and interactive and are responsible for the quadrapole structure in convection seen from the composites the interannual variability assessed from the pop coefficient time series indicates that the 40 day mode is strong during the onset phase of the monsoon in all the years but systematic propagation over the entire season depends crucially on the activity of the oceanic tcz tropical convergence zone the pop analysis of the 15 day mode indicates that this event originates over the equatorial west pacific associated with westward propagating rossby waves amplifies over the northwest tropical pacific and modulates both the continental and oceanic tczs over indian longitudes simultaneously this mode is pronounced during the established phase of the monsoon due to the complexity in the propagational features of both the intraseasonal modes it is concluded that understanding the subseasonal variability of one regional component of the asian summer monsoon asm requires understanding the entire asm system

impact of indian summer monsoon on the south asian high and its influence on summer rainfall over china by using the monthly era 40 reanalysis data and observed rainfall data we investigated the effect of the indian summer monsoon ism on the south asian high sah at 200 hpa and the role played by the sah in summer rainfall variation over china it is found that in the interannual timescale the east west shift is a prominent feature of the sah with its center either over the iranian plateau or over the tibetan plateau when the ism is stronger weaker than normal the sah shifts westward eastward to the iranian plateau tibetan plateau the east west position of sah has close relation to the summer rainfall over china a westward eastward location of sah corresponds to less more rainfall in the yangtze huai river valley and more less rainfall in north china and south china a possible physical process that the ism affects the summer rainfall over china via the sah is proposed a stronger weaker ism associated with more less rainfall over india corresponds to more less condensation heat release and anomalous heating cooling in the upper troposphere over the northern indian peninsula the anomalous heating cooling stimulates positive negative height anomalies to its northwest and negative positive height anomalies to its northeast in the upper troposphere causing a westward eastward shift of the sah with its center over the iranian plateau tibetan plateau as a result an anomalous cyclone anticyclone is formed over the eastern tibetan plateau and eastern china in the upper troposphere the anomalous vertical motions in association with the circulation anomalies are responsible for the rainfall anomalies over china our present study reveals that the sah may play an important role in the effect of ism on the east asian summer monsoon

zonal oscillation of western pacific subtropical high and subseasonal sst variations during yangtze persistent heavy rainfall events abstractthis study examines the relationship between the zonal oscillation of the western pacific subtropical high wpsh and underneath sea surface temperature sst variation on a subseasonal time scale associated with the persistent heavy rainfall phr events over the middle and lower reaches of the yangtze river valley mlyrv in china a total of 76 phr events and 45 break events in the summers of 1979 2011 are first identified over the mlyrv and divided into early and late summer groups during the phr events over the mlyrv for both groups the wpsh stretches more westward accompanied by the positive anomalies of the 500 hpa geopotential height field over east asia and its coastal region south of 30 n and the subseasonal warmer ssts beneath the wpsh western edge the time lagged composites suggest that the wpsh western edge exhibits westward then eastward migration on a subseasonal time scale for the phr events the zonal changes of the wpsh and anomalous circulation and sst anomaly ssta signal

intraseasonal variability of the south china sea summer monsoon the objective of this study is to explore based on the national centers for environmental prediction national center for atmospheric research ncep ncar reanalysis data the intraseasonal variability of the south china sea scs summer monsoon sm in terms of its structure and propagation as well as interannual variations a possible mechanism that is responsible for the origin of the 10 20 day oscillation of the scs sm is also proposed the 30 60 day hereafter the 3 6 mode and 10 20 day hereafter the 1 2 mode oscillations are found to be the two intraseasonal modes that control the behavior of the scssm activities for most of the years both the 3 6 and 1 2 modes are distinct but may not always exist simultaneously in a particular year and their contributions to the overall variations differ among different years thus the interannual variability in the intraseasonal oscillation activity of the scs sm may be categorized as follows the 3 6 category in which the 3 6 mode is more significant in terms of the percentage of variance explained than the 1 2 mode the 1 2 category in which the 1 2 mode is dominant and the dual category in which both the 3 6 and 1 2 modes are pronounced composite analyses of the 3 6 category cases indicate that the 30 60 day oscillation of the scs sm exhibits a trough ridge seesaw in which the monsoon trough and subtropical ridge exist alternatively over the scs with anomalous cyclones anticyclones along with enhanced suppressed convection migrating northward from the equator to the midlatitudes the northward migrating 3 6 mode monsoon trough ridge in the lower troposphere is coupled with the eastward propagating 3 6 mode divergence convergence in the upper troposphere it is also found that for the years in the dual category the scs sm activities are basically controlled by the 3 6 mode but modified by the 1 2 mode composite results of the 1 2 mode category cases show that the 10 20 day oscillation is manifest as an anticyclone cyclone system over the western tropical pacific propagating northwestward into the scs a close coupling also exists between the upper level convergence divergence and the low level anticyclone cyclone it is found that the 1 2 mode of the scs sm mainly originates from the equatorial central pacific although a disturbance from the northeast of the scs also contributes to this mode the flow patterns from an inactive to an active period resemble those associated with a mixed rossby gravity wave observed in previous studies

constraints on water depth of massive sulfide formation evidence from modern seafloor hydrothermal systems in arc related settings the results of three decades of seafloor research provide the most reliable information on the importance of water depth in massive sulfide formation available data from over 130 occurrences show that water depths of seafloor vent sites vary with plate tectonic setting and the regional magmatic and volcanic environment the shallowest hydrothermal systems in subduction related settings are hosted by arc volcanoes these shallow vent sites have a number of features in common with subaerial epithermal systems massive sulfide occurrences in arc related rifts the most likely setting for many ancient analogs are generally restricted to water depths from 700 to 2 000 m with rifts developing within old arc crust at the deeper end of this range back arc spreading centers proximal to arcs host massive sulfide deposits at depths of 1 500 to 2 000 m the deepest hydrothermal systems occur along mature back arc spreading centers distal to volcanic arcs where water depths range from 2 000 to 3 700 m these deeper vent sites probably represent the best modern analogues of ophiolite hosted massive sulfide deposits boiling of the hydrothermal fluids is common at volcanic arcs and in arc related rifts in these environments elevated magmatic gas contents of the hydrothermal fluids can contribute to the widespread occurrence of phase separation and associated gas loss by contrast the high ambient pressures in deep marine hydrothermal systems along mature back arc spreading centers prevent fluids from boiling during their ascent to the seafloor boiling controls the maximum temperature at which hydrothermal fluids discharge at the seafloor and therefore influences the metal content of seafloor sulfide deposits copper rich massive sulfides typically occur at water depths exceeding 1 000 m whereas zn and pb rich occurrences may form at any water depth boiling can be an important control on ag and au grades but is not the only factor controlling precious metal enrichment in massive sulfides shallow marine hot spring deposits can be highly enriched in trace metals such as as hg and sb submarine volcanic arc and back arc settings are geologically complex and significant variations in water depth can occur over short distances paleoenvironmental reconstruction of these environments in ancient volcanic terranes is hampered by the lack of unequivocal volcanological or sedimentological criteria that indicate water depth the relationships established here using modern seafloor observations provide important constraints on the paleoenvironmental setting of ancient volcanic hosted massive sulfide deposits

conifer and angiosperm biomarkers in clay sediments and fossil plants from the miocene clarkia formation idaho usa the aliphatic lipids and terpenoids of conifer and angiosperm macrofossils and the clay sediment from a new site p 37 of the miocene clarkia formation idaho usa were analyzed to evaluate the preservation of characteristic conifer and angiosperm biomarkers in the sediment series of aliphatic lipids terpenoids and steroids similar to the biomarkers found in type locality clarkia p 33 were the predominant compounds in the sediment and in the fossils long chain aliphatic lipids were major compounds in the fossil plants and the sediment but a differentiation of angiosperm and conifer sources is not possible due to their common distribution among all vascular plants in addition to previously reported terpenoids diterpenoids of a conifer origin and several angiosperm derived polar triterpenoids of the oleanane lupane ursane and friedelane classes are reported here for the first time from the clarkia sediments the conifer shoots taxodium glyptostrobus calocedrus contained characteristic conifer biomarkers such as abietane type diterpenoids while characteristic angiosperm triterpenoids were predominant in the angiosperm leaves betula quercus lithocarpus the biomarker compositions of the taxodium and glyptostrobus shoots match the terpenoid patterns previously reported from fossil seed cones of the same genera although conifer macrofossils contribute about 45 to the flora of site p 37 characteristic conifer biomarkers occurred in the sediment in only low amounts while the angiosperm derived triterpenoids were present in comparatively higher abundances the results indicate that the conifers are under represented compared to the angiosperms according to the terpenoid composition of the sediment extract this may be due to the presence of small angiosperm derived particles leaf detritus wax in the sediment and or migration of leaf waxes from the angiosperm leaves into the sediment in contrast the diterpenoids are trapped in the resinous woody tissue of the conifers and are thus disseminated less into the sediment

global extratropical response to diabatic heating variability of the asian summer monsoon abstract global teleconnections associated with the asian summer monsoon convective activities are investigated based on monthly data of 29 northern hemisphere summers defined as june september jjas two distinct teleconnection patterns are identified that are associated respectively with variabilities of the indian summer monsoon and the western north pacific summer monsoon the indian summer monsoon convective activity is associated with a global pattern that has a far reaching connection in both hemispheres whereas the western north pacific summer monsoon convective activity is connected to a southern hemisphere wave train that influences the high latitude south pacific and south america a global primitive equation model is utilized to assess the cause of the global circulation anomalies the model responses to anomalous heatings of both monsoon systems match the general features of the observed circulation anomalies well and they are mainly controlled by linear processes the response patterns ar

the effects of midlatitude waves over and around the tibetan plateau on submonthly variability of the east asian summer monsoon abstract convective variability at submonthly time scales 7 25 days over the yangtze and huaihe river basins yhrbs and associated large scale atmospheric circulation during the mei yu season were examined using interpolated outgoing longwave radiation olr and ncep ncar reanalysis data for 12 yr having active submonthly convective fluctuation over the yhrbs within the period 1979 2004 correlations between convection anomalies over the yhrbs and upper level streamfunction anomalies at every grid point show two contrasting patterns one pattern exhibits high correlations along the northern to eastern peripheries of the tibetan plateau defined as the net pattern whereas the other has high correlations across the tibetan plateau defined as the at pattern composite analysis of the net pattern shows slow southward migration of convection anomalies from the northeastern periphery of the tibetan plateau to southern china in relation to southward migration of the mei yu front caused by simultaneous am

structures and mechanisms of the northward propagating boreal summer intraseasonal oscillation abstract the spatial and temporal structures of the northward propagating boreal summer intraseasonal oscillation bsiso are revealed based on the analysis of both the echam4 model simulation and the ncep ncar reanalysis the bsiso structure and evolution characteristics simulated by the model bear many similarities to those derived from the ncep ncar reanalysis the most notable features are the remarkable meridional asymmetries relative to the bsiso convection in the vorticity and specific humidity fields a positive vorticity perturbation with an equivalent barotropic structure appears a few latitude degrees north of the convection center the maximum specific humidity also shows a clear northward shift in the lower troposphere two internal atmospheric dynamics mechanisms are proposed to understand the cause of the northward propagation of the bsiso the first is the vertical shear mechanism the key process associated with this mechanism is the generation of barotropic vorticity due to the couplin

perylene as an indicator of conifer fossil wood degradation by wood degrading fungi the occurrence of perylene in middle jurassic fossil wood and miocene xylites from poland is described along with its correlation with unsubstituted polycyclic aromatic hydrocarbons pahs as well as cellulose content both middle jurassic and miocene wood remnants were of relatively low maturity ca 0 2 0 3 vitrinite reflectance rr had excellent preservation of biomarkers and biomolecules and in the case of the middle jurassic fossil wood samples generally good preservation of anatomical structures due to early diagenetic mineralisation the results from 42 middle jurassic and 8 miocene most taxonomically defined fossil wood fragments demonstrated a negative correlation between the concentration of perylene and those of generally typical conifer biomarkers e g cadalene dehydroabietane simonellite and retene in addition good correlation r2 0 81 was observed between the ratio of perylene to the above conifer biomarkers and the ratio of pahs phenanthrene and fluoranthene and pyrene to the conifer biomarkers this implies that the high concentration of perylene in fossil wood indicate its extensive degradation during decay transport and early diagenesis we defined a conifer wood degradation index as cwdi perylene perylene cadalene retene simonellite dehydroabietane cwdi perylene perylene cadalene retene simonellite dehydroabietane and observed a wide range of values 0 001 for less degraded wood to 0 95 for highly degraded samples anatomical wood preservation was associated with cwdi values in most of the samples characterised by poorly preserved anatomy high cwdi values were observed while anatomically well preserved samples generally had lower cwdi values we determined similar 13c values for perylene from the fossil wood samples 26 4 to 27 8 whereas the values for the conifer biomarkers were slightly higher and varied from 25 6 to 26 6 in contrast pyrene was depleted in 13c 27 5 to 28 2 the carbon isotope values of perylene are consistent with an origin from wood degrading fungi

mineral deposits of canada a synthesis of major deposit types district metallogeny the evolution of geological provinces and exploration methods wayne d goodfellow editor 1 068 pp geological association of canada mineral deposits division special publication no 5 2007 hardcover isbn 13 978 1 897095 24 9 price members cdn 60 00 non members cdn 80 00 following in the footsteps of other landmark reviews of major ore producing countries such as australia hughes 1990 solomon and groves 1994 and south africa anhaeusser and maske 1986 this substantial 1 000 pages monograph is a great achievement that should be in every geologic research library in the world in many ways it sets a new standard most notably in that all figures and photographs are in color and that the entire volume is available in electronic form both as an included dvd and mostly on the gac website it is common in such compendia to have a spectacular cover photo or frontispiece to catch the reader s attention and this book does not disappoint the frontispiece photo is of a 61 8 kg sample from the dome mine timmins ontario and is stated to contain 20 wt percent gold at today s prices the gold alone would be worth 1 5 million dollars

influence of the anticyclonic anomaly in the subtropical jet over the western tibetan plateau on the intraseasonal variability of the summer asian monsoon in early summer abstractthe upper level troposphere over the western tibetan plateau where the subtropical jet is located in summer is a region of marked intraseasonal variability in geopotential height gph this study investigates the influence of an anomaly in this region on the summer asian monsoon to this end the gph index is defined as the daily geopotential height anomaly at 200 hpa over the region based on 40 yr european centre for medium range weather forecasts re analysis era 40 data composites with respect to strongly positive values of the gph index are analyzed the results indicate that the temporary anomaly in the subtropical jet influences the monsoon over south asia southeast asia and probably also over east asia because of two main processes the eastward propagation of quasi stationary rossby wave anomalies at upper and lower levels along the subtropical jet and a belt of strong westerlies at 15 n arabian sea bay of bengal the philippines the two mechanisms that underlie the lower level ro

structural analysis of aeromagnetic data from the rainy river block wabigoon subprovince minnesota usa and ontario canada strain partitioning along a neoarchean terrane boundary and implications for mineral exploration abstract high resolution aeromagnetic data are used to constrain the structural architecture and mineral potential of the neoarchean rainy river block rrb a sigma shaped wedge of till covered volcano plutonic rocks that form the southern margin the wabigoon subprovince and span the international border between northern minnesota usa and western ontario canada reduced to pole transformed upward continued and derivative enhanced aeromagnetic data show that the rrb can be divided into three structural domains the rainy lake wrench zone rlwz border zone bz and oaks belt ob strain intensity decreased from east strongly deformed rlwz to west moderately deformed ob the rlwz experienced superimposed folding that resulted in complex rock geometries and sigmoidal patterns in the aeromagnetic data a large northeast trending syncline partially represented by an aeromagnetic low that is cut by similarly oriented shear zones and faults comprises the bz the ob is interpreted to occupy a regional scale strain shadow and is composed of a relatively well preserved and magnetically heterogeneous volcanic pile and subvolcanic intrusion that have been overturned and are steeply north dipping as the rrb is fault bounded terrane boundary and hosts numerous mafic intrusions it was a regional zone of synvolcanic and syntectonic paleo permeability and therefore has potential for hosting orogenic gold and volcanogenic massive sulfide vms deposits however linear fault geometries throughout most of the rrb were not conducive to formation of large orogenic gold deposits and pervasive deformation in the rlwz may have compromised preservation of hypogene vms mineralized zones thus the structurally preserved ob is the most prospective area for hosting vms deposits in the rrb whereas the bz and surrounding rocks are prospective for hosting orogenic gold deposits near a 30 km long restraining bend in the quetico fault

geological analysis of aeromagnetic data from southwestern alaska implications for exploration in the area of the pebble porphyry cu au mo deposit aeromagnetic data are used to better understand the geology and mineral resources near the late cretaceous pebble porphyry cu au mo deposit in southwestern alaska the reduced to pole rtp transformation of regional scale aeromagnetic data shows that the pebble deposit is within a cluster of magnetic anomaly highs similar to pebble the iliamna kijik and neacola porphyry copper occurrences are in magnetic highs that trend northeast along the crustal scale lake clark fault a high amplitude short to moderate wavelength anomaly is centered over the kemuk occurrence an alaska type ultramafic complex similar anomalies are found west and north of kemuk a moderate amplitude moderate wavelength magnetic low surrounded by a moderate amplitude short wavelength magnetic high is associated with the gold bearing shotgun intrusive complex the rtp transformation of the district scale aeromagnetic data acquired over pebble permits differentiation of a variety of jurassic to tertiary magmatic rock suites jurassic cretaceous basalt and gabbro units and late cretaceous biotite pyroxenite and granodiorite rocks produce magnetic highs tertiary basalt units also produce magnetic highs but appear to be volumetrically minor eocene monzonite units have associated magnetic lows the rtp data do not suggest a magnetite rich hydrothermal system at the pebble deposit the 10 km upward continuation transformation of the regional scale data shows a linear northeast trend of magnetic anomaly highs these anomalies are spatially correlated with late cretaceous igneous rocks and in the pebble district are centered over the granodiorite rocks genetically related to porphyry copper systems the spacing of these anomalies is similar to patterns shown by the numerous porphyry copper deposits in northern chile these anomalies are interpreted to reflect a late cretaceous magmatic arc that is favorable for additional discoveries of late cretaceous porphyry copper systems in southwestern alaska

eddy shedding from the upper tropospheric asian monsoon anticyclone abstract the authors investigate the transient behavior of the asian monsoon anticyclone in the summertime upper troposphere for the four northern summers 1987 90 the evolution of potential vorticity near the tropopause shows the development of westward migrating anticyclones breaking off from the main anticyclone a few times each summer these disturbances are relatively shallow being confined to the upper troposphere

crustal scale structures in the proterozoic mount isa inlier of north australia their seismic response and influence on mineralisation abstract the proterozoic mount isa inlier in northern australia is prospective for base metals and gold it contains a western fold belt including the leichhardt river fault trough and an eastern fold belt separated by older basement rocks of the kalkadoon leichhardt belt sediments and volcanics in both fold belts were deposited in rifts which were subsequently shortened by up to 50 mineralisation appears to be partitioned large tonnage lead and zinc deposits are more prevalent in the leichhardt river fault trough and most gold and copper occurrences are in the eastern fold belt cross sections of the inlier derived from coincident seismic reflection and refraction profiling are dominated by the youngest tectonic events the refraction data imply a west dipping lens of high velocity intermediate to mafic rock in the middle to upper crust in the east of the inlier it is collinear with another lens in the lower crust in the west of the inlier the lenses form a belt of high velocity rock cutting the crust from top to bottom and from east to west the reflection data reveal different styles of compression related structures in the east and west of the inlier thin skinned tectonics dominate in the eastern fold belt the sediments and volcanics are thrust to the west along a number of shallowly east dipping upper crustal detachments the detachments in turn are cut by steeply east dipping reverse faults which link into the zone of high velocity rocks defined by the refraction data in contrast faults in the western fold belt are steep and penetrate to mid crustal levels and probably also link into the belt of high velocity material deeper in the crust the partitioning into different tectonic styles occurs across the kalkadoon leichhardt belt which appears to have acted as a buttress during the crustal shortening published mineralisation models attribute the lead zinc mineralisation to circulating fluids at shallow crustal levels within the leichhardt river fault trough high reflectivity of faults with a close spatial association with mineralisation is attributed to alteration along the fault caused by migrating fluids copper gold mineralisation in the eastern fold belt is scattered but known major deposits lie along trend from a thrust fault shown in the seismic data to be highly reflective this fault links via the upper crustal detachments and the high velocity lenses into the middle to lower crust and is seen as a likely control on fluid migration pathways from lower crustal levels into the supracrustal eastern fold belt the partitioning of the tectonic styles seen in the seismic data and the mode of linking of faults into the middle to lower crust are seen as primary factors in the partitioning of mineralisation in the region

the bousquet 2 dumagami world class archean au rich volcanogenic massive sulfide deposit abitibi quebec metamorphosed submarine advanced argillic alteration footprint and genesis the archean bousquet 2 dumagami deposit is an au rich volcanogenic massive sulfide deposit vms with a total production of 3 87 moz au 2 77 moz ag 80 000 metric tons t cu and 5 000 t zn the deposit is located within the doyon bousquet laronde mining camp in northwestern quebec and hosted by the 2704 to 2695 ma blake river group the world s most productive volcanic assemblage for au rich vms deposits the bousquet 2 dumagami deposit consists of stacked deformed and transposed semimassive to massive pyrite rich lenses breccia zones and associated sulfide veins and stringer zones hosted by the upper member of the bousquet formation 50 to 100 m stratigraphically below the 2687 ma cadillac group sedimentary rocks the main ore zone is known as the massive hangingwall zone at the bousquet 2 mine and zone 5 at the dumagami mine another semimassive to disseminated pyrite rich auriferous zone with coarsely recrystallized massive pyrite is present in the footwall massive footwall zone the massive hangingwall zone is an au ag cu zn sheet like semimassive to massive pyrite rich sulfide lens intermixed with vein and breccia zones the dominant ore type consists of au cu mineralization but its upper and eastern parts are enriched in zn the ore consists of a complex assemblage of sulfides sulfosalts and native gold including abundant pyrite sphalerite a few percent of chalcopyrite bornite and galena with some visible gold the massive hangingwall zone was formed by subsea floor replacement of footwall calc alkaline dacitic volcaniclastic rocks and hanging wall blue quartz phyric rhyolite despite significant north south shortening and metamorphism which was responsible for transposition flattening folding and recrystallization mineralogical gradients related to alteration induced compositional variations can still be identified a number of different metamorphic mineral assemblages can be mapped over several tens of meters from distal to proximal to the ore 1 quartz muscovite mn garnet biotite chlorite 2 quartz muscovite pyrite 3 quartz muscovite andalusite pyrophyllite pyrite with topaz and diaspore and 4 massive quartz pyrite a quartz carbonate biotite assemblage occurs in the hanging wall of the zn rich massive hangingwall zone and is hosted by andesitic sills the thickness of each of these assemblages varies from a few meters to tens of meters all metamorphosed alteration assemblages are characterized by strong progressive na2o depletion gains in mno fe2o3 total mgo and cao are recorded in the quartz muscovite mngarnet biotite chlorite assemblage whereas gains in k2o and losses in cao occur in the quartz muscovite pyrite assemblage in the quartz muscovite andalusite pyrophyllite pyrite and the proximal massive quartzpyrite assemblages all oxides except sio2 fe2o3 total and tio2 were strongly to almost entirely leached the andalusite kyanite pyrophyllite bearing aluminous assemblages are interpreted to represent metamorphosed equivalents of synvolcanic alteration produced by acidic and oxidizing hydrothermal fluids i e metamorphosed advanced argillic style alteration whereas the massive quartz pyrite assemblage is similar to the massive silicic alteration commonly associated with advanced argillic alteration the timing of au mineralization is considered to be close to the age of the host rhyolite 2697 8 1 ma and the age of the overlying felsic volcanic rocks 2697 5 1 1 ma the major au endowment of the doyon bousquet laronde mining camp may be related to favorable source rock or au reservoirs specific to the lower crust or upper mantle beneath the eastern archean blake river group exploration for additional au rich vms in this environment should focus on distal quartz and mn rich garnet biotite and proximal aluminous assemblages with anomalously high au and or cu and zn in intermediate to felsic transitional to calc alkaline volcanic or volcaniclastic rocks located underneath a younger sedimentary cover

anticorrelated intensity change of the quasi biweekly and 30 50 day oscillations over the south china sea 1 over the south china sea the year to year variations in the intensity of the quasi biweekly qbw and 30 50 day oscillations during june july are anti correlated an explanation is offered for the out of phase relationship we found during strong qbw years the june july mean convection and easterly vertical shear are enhanced over the equatorial western central pacific with corresponding low level cyclonic meridional shear to the northwest these conditions concurring with the equatorial eastern pacific warming are favorable for emanation of moist rossby waves from the equatorial western pacific on the other hand the 30 50 day becomes active when the mean convection is enhanced over the eastern indian ocean and maritime continent where this mode stems from and develops which often corresponds to cold western io one of these two large scale settings often occurs in the absence of the other so that when one mode is strong during june july the other mode tends to be weak

evolution and dynamics of summertime blocking over the far east and the associated surface okhotsk high time evolution and dynamics of an upper level blocking ridge over the far east and the associated surface high over the sea of okhotsk that give rise to abnormal summertime coolness over eastern japan are investigated through a composite analysis applied to distinct surface high events the formation mechanism and vertical structure of the blocking differ fundamentally between may and july attributable to seasonal changes in the jet structure storm track activity over the far east and the land sea thermal contrast within the okhotsk region in may forcing from migratory eddies is strong enough for precursory anticyclonic anomalies retrograding slowly over the north pacific to develop into a blocking ridge the ridge remains equivalent barotropic under the weak land sea thermal contrast in the okhotsk region in contrast the eddy forcing is no longer the primary factor for the blocking formation in july in the presence of the weakened and split westerlies rather the propagation of a stationary rossby wave packet that has emanated from precursory anticyclonic anomalies over northern europe stagnates over the far east and the subsequent local breaking of the packet leads to the blocking formation in a particular case in july 1993 a wave packet involved in blocking formation could be traced back as far upstream as the east coast of north america over the two previous weeks acting on the strong thermal contrast in july between the cool sea surface and a warm land mass to the west the anomalous surface easterlies induced by the blocking ridge can build up a cold surface anticyclone through cold advection rendering the blocking anomalies distinctly baroclinic copyright 2004 royal meteorological society

20 50 day oscillation of summer yangtze rainfall in response to intraseasonal variations in the subtropical high over the western north pacific and south china sea the spatio temporal variability in summer rainfall within eastern china is identified based on empirical orthogonal function eof analysis of daily rain gauge precipitation data for the period 1979 2003 spatial coherence of rainfall is found in the yangtze basin and a wavelet transform is applied to the corresponding principal component to capture the intraseasonal oscillation iso of yangtze rainfall the ensemble mean wavelet spectrum representing statistically significant intraseasonal variability shows a predominant oscillation in summer yangtze rainfall with a period of 20 50 days a 10 20 day oscillation is pronounced during june and july this finding suggests that the 20 50 day oscillation is a major agent in regulating summer yangtze rainfall composite analyses reveal that the 20 50 day oscillation of summer yangtze rainfall arises in response to intraseasonal variations in the western north pacific subtropical high wnpsh which in turn is modulated by a rossby wave like coupled circulation convection system that propagates northward and northwestward from the equatorial western pacific when an anomalous cyclone associated with this rossby wave like system reaches the south china sea scs and philippine sea the wnpsh retreats northeastward due to a reduction in local pressure under these conditions strong monsoonal southwesterlies blow mainly toward the scs philippine sea while dry conditions form in the yangtze basin with a pronounced divergent flow pattern in contrast the movement of an anomalous anticyclone over the scs philippine sea results in the southwestward extension of the wnpsh consequently the tropical monsoonal southwesterlies veer to the northeast over the scs and then converge toward the yangtze basin producing wet conditions therefore the 20 50 day oscillation of yangtze rainfall is also manifest as a seesaw pattern in convective anomalies between the yangtze basin and the scs philippine sea a considerable zonal shift in the wnpsh is associated with extreme dry wet episodes in the yangtze basin with an abrupt eastward westward shift in the wnpsh generally leading the extreme negative positive yangtze rainfall anomaly by a 3 8 period of the 20 50 day oscillation this finding may have implications for improving extended range weather forecasting in the yangtze basin

lithospheric controls on the formation of provinces hosting giant orogenic gold deposits ages of giant gold systems 500 t gold cluster within well defined periods of lithospheric growth at continental margins and it is the orogen scale processes during these mainly late archaean palaeoproterozoic and phanerozoic times that ultimately determine gold endowment of a province in an orogen a critical factor for giant orogenic gold provinces appears to be thickness of the subcontinental lithospheric mantle sclm beneath a province at the time of gold mineralisation as giant gold deposits are much more likely to develop in orogens with subducted oceanic or thin continental lithosphere a proxy for the latter is a short pre mineralisation crustal history such that thick sclm was not developed before gold deposition in constrast orogens with protracted pre mineralisation crustal histories are more likely to be characterised by a thick sclm that is difficult to delaminate and hence such provinces will normally be poorly endowed the nature of the lithosphere also influences the intrinsic gold concentrations of potential source rocks with back arc basalts transitional basalts and basanites enriched in gold relative to other rock sequences thus segments of orogens with thin lithosphere may enjoy the conjunction of giant scale fluid flux through gold enriched sequences although the nature of the lithosphere plays the crucial role in dictating which orogenic gold provinces will contain one or more giant deposits the precise siting of those giants depends on the critical conjunction of a number of province scale factors such features control plumbing systems traps and seals in tectonically and lithospherically suitable terranes within orogens

subseasonal intensity variation of the south asian high in relationship to diabatic heating observation and cmip5 models this study investigates the subseasonal intensity variation of south asian high sah and the dynamic linkage with precipitation induced diabatic heating during the summer of 1979 2005 based on the observation and 18 models from the coupled model intercomparison project cmip5 the sah s intensity variation with a period of approximately 10 36 days is identified both in the observation and 18 models by performing an empirical orthogonal function eof analysis on the standardized subseasonal anomalies in geopotential height at 100 hpa over the sah s main body region with the observed strengthening of the sah an enhanced rainfall belt between 70 120 e migrates northward from the equatorial region the northward propagating rainfall belt occupies almost the whole indian subcontinent indochina peninsula and subtropical east asian regions between 20 40 n when the sah reaches the strongest the relative vorticity diagnosis reveals the dynamical linkage between the subseasonal sah s intensity variation and the precipitation anomalies over the asian monsoon region 1 the observed northward propagating rainfall band forms a horizontal gradient of diabatic heating favoring an enhancement of the sah over its southern part 2 when the rainfall band approaches the regions of south and east asia between 20 40 n the increased vertical gradient of diabatic heating in the upper level contributes significantly to the intensification of the sah 3 the horizontal advection process favors the westward expansion of the sah the observation to model comparisons indicate that the model s capacity to reproduce the sah s intensity variation is highly associated with simulations of the anomalous rainfall band and its northward propagation a realistic reproduction of precipitation anomalies is fundamental to simulating the dynamical processes related to diabatic heating and thus the simulation of the sah s subseasonal intensity variation

low temperature alteration at the world class laronde penna archean au rich volcanogenic massive sulfide deposit abitibi subprovince quebec canada evidence from whole rock oxygen isotopes the oxygen isotope composition of 169 whole rock samples from the world class laronde penna au rich volcanogenic massive sulfide deposit range from 6 5 to 22 0 fractional crystallization from basalt to rhyolite accounts for a variation of approximately 2 in primary whole rock 18o values the remaining variance in whole rock 18o values found at laronde penna must therefore be ascribed to water rock exchange with hydrothermal fluids the metamorphosed hydrothermally altered host rocks have been subdivided according to mineralogical assemblages which display weak covariance with 18o values and whole rock geochemical alteration indices water rock equilibrium exchange models indicate that the high 18o values that characterize the laronde penna deposit are compatible with low temperature 150oc hydrothermal alteration at high water rock oxygen atomic ratios 1 50 zones of lower 18o values stratigraphically beneath the principal ore lens 20 north indicate local zones of higher temperature hydrothermal alteration the oxygen isotope composition of the hydrothermal fluid is estimated to have been 5 as a consequence of mixing between seawater 18o 0 and a component of magmatic water degassed from the volcanic and intrusive rocks associated with the laronde penna deposit

offset and evolution of the gowk fault s e iran a major intra continental strike slip system abstract we use drainage reconstructions to estimate long term offsets on the gowk fault an oblique right lateral strike slip fault in eastern iran on which there have been a number of recent large earthquakes a 3 km horizontal offset is inferred from well preserved geomorphology we further identify a total cumulative offset of 12 km which produces a simple reconstruction of geomorphology across the fault filling in pull apart basins restoring rivers to linear courses across the fault trace and aligning structural and bed rock features the probable age of the gowk fault and k ar dating of offset basalts north of the study region suggest an overall slip rate of 1 5 2 4 mm year this is small compared with the overall 10 20 mm year of shear expected between central iran and afghanistan and the deficit is likely to have been accommodated on other faults east of the gowk fault drainage displaced by dextral movement leads to the development of a series of basins along the fault and a longitudinal topographic profile that resembles an asymmetric saw tooth the geomorphic evolution of the fault zone at the surface includes both normal and reverse faulting components reflecting a probable ramp and flat structure in cross section this interpretation is consistent with evidence from the analysis of seismological radar and surface rupture data in recent earthquakes

genesis of the south asian high and its impact on the asian summer monsoon onset abstractthe formation of the south asian high sah in spring and its impacts on the asian summer monsoon onset are studied using daily 40 yr ecmwf re analysis era 40 data together with a climate mean composite technique and potential vorticity diabatic heating pv q analysis results demonstrate that about 2 weeks before the asian summer monsoon onset a burst of convection over the southern philippines produces a negative vorticity source to its north the sah in the upper troposphere over the south china sea is then generated as an atmospheric response to this negative vorticity forcing with the streamline field manifesting a gill type pattern afterward the persistent rainfall over the northern indochinese peninsula causes the sah to move westward toward the peninsula consequently a trumpet shaped flow field is formed to its southwest resulting in divergence pumping and atmospheric ascent just over the southeastern bay of bengal bob near the surface as a surface anticyclone is formed over t

event based extreme precipitation in central eastern china large scale anomalies and teleconnections event based extreme precipitation eep defined as an extreme precipitation event no less than 1 mm for continuous days having at least one daily precipitation exceeding the 90th percentile are categorized into three types according to the time distribution pattern tdp of extreme precipitation daily intense precipitation appearing only at the first half of event tdp1 at both the first and second halves tdp2 and only at the second half of event tdp3 this study focuses on the tdp1 and tdp2 types which occur much more frequently in the central eastern china and investigates associated distinguishing large scale teleconnection patterns the tdp1 events dominantly occur in mid to late spring which are associated with the silk road pattern srp wave train manifested from western europe to northwest pacific along the subtropical westerly jet the tripolar sea surface temperature sst anomalous pattern over the north atlantic ocean i e low sst anomalies in the azores islands two high sst anomalies over the greenland and subtropical north atlantic are mainly attributed to force the srp wave meanwhile the enhanced northwestward moisture transport from the south china converges with the southeastward moisture transport related to the srp from the north china resulting in the tdp1 extreme precipitation events over the central eastern china the tdp2 events are closely conjunction with the meiyu precipitation in the yangtze huai river basin in summer during the tdp2 events the east asia pacific eap teleconnection is exhibited along the east asia coasts which is triggered by the anomalous convection in the western north pacific an anomalous anticyclone related to the eap teleconnection contributes to the westward stretch of the western pacific subtropical high providing significant enhanced moisture transportation toward the yangtze huai river basin correspondingly the meridional gradient of the equivalent potential temperature theta e is intensified and favored of forming meiyu front precipitation this study highlights the definition of eep event emphasizing the tdp of extreme precipitation and distinguished features of occurring seasons and large scale circulations associated with the two dominant types of eep events

how are heat waves over yangtze river valley associated with atmospheric quasi biweekly oscillation over yangtze river valley yrv where heat wave hw events most frequently occur in china during 1979 2014 30 out of 57 hw events nearly 55 in july and august is found to be related with the dry phases of atmospheric quasi biweekly oscillation qbwo when a significant low level anticyclonic anomaly laa associated with qbwo appears over yrv temperature rises sharply according to the adiabatic heating caused by subsidence and the enhanced downward solar radiation due to decreased clouds the laa with subsidence over yrv is primarily generated by quasi biweekly atmospheric waves which are classified to three types through case by case categorization named as mid latitude wavetrain wnp western north pacific wavetrain and double wavetrains respectively the mid latitude wavetrain qbwo causes the laa through subsidence induced by upper level cyclonic vorticity which is associated with an eastward southeastward migrating wave train from eastern europe to wnp in the upper troposphere the wnp wavetrain qbwo forms laa through a northwestward migrating lower tropospheric wave train emanating from tropical wnp to southeastern china the double wavetrains qbwo triggers laa through both the low level shear anticyclonic vorticity provided by a low level northwestward westward propagating wave train from tropical wnp to south china sea and the upper level positive vorticity associated with an eastward southeastward migrating wave train from eastern europe to southeastern china in the upper troposphere in all cases south asian high extends eastward and wnp subtropical high extends westward during hw events tracing these distinct precursory circulation anomalies may facilitate better understanding and short medium range forecast of hw

geologic interpretation of aeromagnetic and chemical data from the oaks belt wabigoon subprovince minnesota implications for au rich vms deposit exploration the oaks belt ob is a neoarchean volcanic complex located in northwestern minnesota usa it is part of the wabigoon granite greenstone terrane that hosts the world class rainy river gold deposit

northern hemisphere summer monsoon singularities and climatological intraseasonal oscillation abstract using climatological pentad mean outgoing longwave radiation olr and european centre for medium range weather forecasts analysis winds the authors show that the northern hemisphere summer monsoon displays statistically significant climatological intraseasonal oscillations cisos the extreme phases of ciso characterize monsoon singularities monsoon events that occur on a fixed pentad with usual regularity whereas the transitional phases of ciso represent the largest year to year monsoon variations the ciso results from a phase locking of transient intraseasonal oscillation to annual cycle it exhibits a dynamically coherent structure between enhanced convection and low level convergent upper level divergent cyclonic anticyclonic circulation its phase propagates primarily northward from the equator to the northern philippines during early summer may july and westward along 15 n from 170 e to the bay of bengal during august and september the propagation of ciso links monsoon singular

formation of the neoarchean bad vermilion lake anorthosite complex and spatially associated granitic rocks at a convergent plate margin superior province western ontario canada abstract the bad vermilion lake anorthosite complex henceforth the bvla complex in western ontario is one of the well exposed anorthosite bearing archean layered intrusions in the superior province canada this study presents new whole rock major and trace element data for the various units of the complex oxygen isotope data for the anorthosite and major and trace element data for the spatially associated granitic rocks intruding the bvla complex to constrain their petrogenetic and geodynamic origin zircons from granitic rocks have yielded a 207pb 206pb age of 2716 18 ma constraining the minimum intrusion age of the complex despite deformation and greenschist facies metamorphism primary igneous textures are locally well preserved in the bvla complex its whole rock major and trace elemental compositions and the oxygen isotopic systematics appear not to have been substantially modified by deformation and metamorphism mantle like oxygen isotope signatures and major and trace element compositions are inconsistent with significant crustal contamination of the bvla complex during its emplacement the existence of primary calcic igneous plagioclase coherent negative nb anomalies nb nb 0 08 0 88 and geochemical similarities between gabbros from the bvla complex and gabbros from cenozoic arcs collectively suggest an intra oceanic subduction zone geodynamic setting for the complex near flat ree patterns in the various units of the bvla complex suggest that they were derived from melting of a shallow source beneath a subarc mantle wedge trends in immobile major e g mgo and trace e g zr element data indicate that the mineralogical composition of the complex can be explained by fractional crystallization and accumulation of olivine orthopyroxene clinopyroxene plagioclase and possibly amphibole compositionally the bordering granitic rocks are a2 type and strongly enriched in th and ree 100 times chondrite and depleted of ba sr eu and ti we suggest that they formed in a post collisional extensional tectonic regime following emplacement of the bvla complex in an oceanic arc

strain analysis and rheology contrasts in polymictic conglomerates an example from the seine metaconglomerates superior province canada deformed conglomerates typically display contrasting strains between different lithological clast populations and matrix which can be exploited to provide information about effective viscosity contrasts we analyzed three different clast populations granitoid mafic volcanic and felsic volcanic across a strain gradient in the seine metaconglomerates of ontario canada we calculated finite strain using the rf 4 method and bootstrap statistics granitoid clasts exhibited the least amount of strain while the mafic and felsic clasts had similar greater strains we assumed that the bulk finite strain was recorded by the mafic clasts given their large proportion of the rock and their similar composition to the matrix we calculated effective viscosity contrasts using the finite strain information assuming newtonian viscous rheology the two volcanic clast populations have similar effective viscosities regardless of strain magnitude with ratios of felsic mafic ranging from 0 27 to 2 12 and average ratio of 1 19 the granitoid clasts are significantly more competent than the mafic clasts with effective viscosity ratios ranging from 2 35 to 12 39 and average ratio of 5 61 the results are consistent with a qualitative

characterizing two types of transient intraseasonal oscillations in the eastern tibetan plateau summer rainfall during summer the intraseasonal disturbances over the eastern tibetan plateau etp can initiate development of severe weather system downstream previous studies yielded inconsistent results on the intraseasonal variability isv of summer rainfall in terms of periodicity genesis process and propagation pathway over the ept based on small samples in this study we detected two dominant peaks of transient isv centered on quasi biweekly 12 24 days qbw and quasi 9 8 11 days using daily rainfall data over the etp during the period of 1992 2012 composite analysis revealed that the two isvs were predominantly associated with the non stationary wave trains which traveled along different pathways for the qbw its mid latitude wave train featured a upper level southeastward migration originating in northern europe and traveling via the east european plain the ural mountains lake balkhash lake baikal the mongolian plateau and then continued southward to the etp and south asia and its tropical wave train was characterized with a northwestward northward migration in low level starting from the philippine sea ps south china sea scs region moving over northern bay of bengal scs region and arriving over the southern fridge of tp and southern china in contrast for quasi 9 day the most significant mid latitudes variability featured an eastward propagating upper level wave train originating from western europe passing across the mediterranean the black and caspian seas arriving over the tp and moving towards east asia and the most evident tropical variability exhibited a clear northwestward westward migration of a low level wave train originating from ps passing over taiwan and subsequently moving towards southeastern china their different spatiotemporal features of associated wave trains caused their distinct linkages with eastern china rainfall anomalies a meridional pattern with a giant ural mountain ridge was the most remarkable precursory signals in upstream region before the qbw wet phase occurrence which was different from the quasi 9 day the major processes generating the local wet spells for the two modes were commonly linked to the preceding boundary warming the upper level negative vorticity and low level prevalent winds which triggered the ascending anomaly and lower tropospheric pre moistening we also discussed the co variation of the wave trains between mid latitudes and low latitudes the distinct evolution related with the two isvs over the etp described here may provide a useful guidance for 2 3 weeks extended range forecasts over the etp and its downstream regions

testing models for obliquely plunging lineations in transpression a natural example and theoretical discussion theory predicts that stretching lineations in an ideal vertical transpressional zone should be either vertical or horizontal many field descriptions of transpressional zones however indicate a range of lineation orientations between these extremes several theoretical models have been developed to explain such departures from expected lineation orientation and we discuss these in the context of a field example from the archean superior province in the north american craton existing models are insufficient to explain obliquely plunging lineations in this example because 1 obliquely plunging lineations cannot be accounted for by shear zone boundary effects imposed by a no slip condition 2 foliations and lineations vary independently 3 the vorticity normal section is subhorizontal limiting possibilities for inclined simple shear 4 high vorticity is needed for finite strains and lineations to match previously proposed triclinic models but vorticity is relatively low and 5 juxtaposed east and west plunging lineations are unlikely in the previously proposed triclinic models because existing theoretical models are not applicable to our field example we contemplate a new model to explain obliquely plunging lineations within quasi homogeneous transpression

petrology of the rainy lake area minnesota usa implications for petrotectonic setting of the archean southern wabigoon subprovince of the canadian shield the rainy lake area in northern minnesota and southwestern ontario is a late archean 2 7 ga granite greenstone belt within the wabigoon subprovince of the canadian shield in minnesota the rocks include mafic and felsic volcanic rocks volcaniclastic chemical sedimentary rocks and graywacke that are intrucded by coeval gabbro tonalite and granodiorite new data presented here focus on the geochemistry and petrology of the minnesota part of the rainy lake area igneous rocks in the area are bimodal the mafic rocks are made up of three distinct suites 1 low tio2 tholeiite and gabbro that have slightly evolved mg numbers 63 49 and relatively flat rare earth element ree patterns that range from 20 8 x chondrites ce ybn 0 8 1 5 2 high tio2 tholeiite with evolved mg numbers 46 29 and high total ree abundances that range from 70 40 x chondrites ce ybn 1 8 3 3 and 3 calc alkaline basaltic andesite and geochemically similar monzodiorite and lamprophyre with primitive mg numbers 79 63 enriched light rare earth elements lree and depleted heavy rare earth elements hree these three suites are not related by partial melting of a similar source or by fractional crystallization of a common parental magma they resulted from melting of heterogeneous archean mantle the felsic rocks are made up of two distinct suites 1 low al2o3 tholeiitic rhyolite and 2 high al2o3 calc alkaline dacite and rhyolite and consanguineous tonalite the tholeiitic felsic rocks are high in y zr nb and total ree that are unfractionated and have pronounced negative eu anomalies the calcalkaline felsic rocks are depleted in y zr and nb and the ree that are highly fractionated with high lree and depleted hree and display moderate negative eu anomalies both suites of felsic rocks were generated by partial melting of crustal material the most reasonable modern analog for the paleotectonic setting is an immature island arc the bimodal volcanic rocks are intercalated with sedimentary rocks and have been intruded by pre and syntectonic granitoid rocks however the geochemistry of the mafic rocks does not correlate fully with that of mafic rocks in modern are evvironments the low tio2 tholeiite is similar to both n type mid ocean ridge basalt morb and low k tholeiite from immature marginal basins the calc alkaline basaltic andesite is like that of low k calc alkaline mafic volcanic rocks from oceanic volcanic arcs however the high tio2 tholeiite is most similar to modern e type morb which occurs in oceanic rifts the conundrum may be explained by 1 rifting of a pre existing immature arc system to produce the bimodal volcanic rocks and high tio2 tholeiite 2 variable enrichment of a previously depleted archean mantle to produce both the low and high tio2 tholeiite and the calc alkaline basaltic andesite and or 3 enrichment of the parental rocks of the high tio2 tholeiite by crustal contamination

mechanism of the northward propagating intraseasonal oscillation insights from a zonally symmetric model abstract the propagation and initiation mechanisms of the boreal summer intraseasonal oscillation bsiso in the south asian summer monsoon are examined with a zonally symmetric atmospheric model in the axially symmetric model the effects of zonally propagating atmospheric waves are intentionally excluded the model specifies mean flows and depicts the lowest baroclinic mode and a barotropic mode in the free troposphere the two vertical modes are coupled by the time mean vertical wind shear the model atmosphere produces a 15 20 day oscillation which is characterized by northward propagation of convection from south of the equator to the indian monsoon trough region and a reinitiation of convection in the region between 10 s and the equator the northward propagation in the model is produced by the free troposphere barotropic divergence which leads convection by about a quarter of a cycle the vertical advection of summer mean easterly vertical wind shear by perturbation vertical motion inside the con

seasonal evolution of the upper tropospheric westerly jet core over east asia the location change of the westerly jet core at upper troposphere in june and july is investigated by using the ncep ncar reanalysis data the results show that the location of the westerly jet core changes rapidly from 140 e to 90 e during 35th 39th pentads which corresponds to the plum rain period over east asia the location change of the jet core is actually the relative intensity change of the different westerly jet centers the meridional temperature contrast in the troposphere is associated with the rapid location change of the jet core the diabatic heating changes are the primary factor determining the seasonal evolution of the westerly jet core over east asia

intraseasonal teleconnection between the summer eurasian wave train and the indian monsoon this study investigated the most recurrent coupled pattern of intraseasonal variability between midlatitude circulation and the indian summer monsoon ism the leading singular vector decomposition svd pattern reveals a significant coupled intraseasonal variation between a rossby wave train across the eurasian continent and the summer monsoon convection in northwestern india and pakistan hereafter referred to as nism the wave train associated with an active phase of nism rainfall displays two high pressure anomalies one located over central asia and the other over northeastern asia they are accompanied by increased rainfall over the western siberia plain and northern china and decreased rainfall over the eastern mediterranean sea and southern japan the circulation of the wave train shows a barotropic structure everywhere except the anomalous central asian high located to the northwest of india where a heat induced baroclinic circulation structure dominates the time lagged svd analysis shows that the midlatitude wave train originates from the northeastern atlantic and traverses europe to central asia the wave train enhances the upper level high pressure and reinforces the convection over the nism region meanwhile it propagates farther toward east asia along the waveguide provided by the westerly jet after an outbreak of nism convection the anomalous central asian high retreats westward composite analysis suggests a coupling between the central asian high and the convective fluctuation in the nism the significance of the midlatitude ism interaction is also revealed by the close resemblance between the individual empirical orthogonal functions and the coupled svd modes of the midlatitude circulation and the ism it is hypothesized that the eastward and southward propagation of the wave train originating from the northeastern atlantic contributes to the intraseasonal variability in the nism by changing the intensity of the monsoonal easterly vertical shear and its associated moist dynamic instability on the other hand the rainfall variations over the nism reinforce the variations of the central asian high through the monsoon desert mechanism thus reenergizing the downstream propagation of the wave train the coupling between the eurasian wave train and nism may be instrumental for understanding their interaction and can provide a way to predict the intraseasonal variations of the indian summer monsoon and east asian summer monsoon

biweekly and 21 30 day variations of the subtropical summer monsoon rainfall over the lower reach of the yangtze river basin abstract the lower reach of the yangtze river basin lyrb is located at the central region of the mei yu and baiu front which represents the subtropical east asian ea summer monsoon based on the newly released daily rainfall data two dominant intraseasonal variation isv modes are identified over the lyrb during boreal summer may august with spectral peaks occurring on day 15 the biweekly mode and day 24 the 21 30 day mode these two modes have comparable intensities and together they account for above about 57 of the total intraseasonal variance both isv modes exhibit baroclinic structures over the lyrb at their extreme phases however the genesis and evolutions associated with the two modes are different considering the genesis of their extreme wet phases over the lyrb the biweekly mode is initiated by a midlatitude jet stream vorticity anomaly moving southeastward while the 21 30 day mode is primarily associated with a low level westward propagation of an anticyclonic anomaly from

regional and local controls on archean rock hosted cobalt mineralization at the mcara deposit southern superior province ontario canada the mcara deposit is in eastern ontario canada and is hosted in an archean inlier to the paleoproterozoic huronian basin it is currently estimated to contain 2 4 million pounds of cobalt at an

impact of the indian ocean sst basin mode on the asian summer monsoon 1 following an el nino event a basin wide warming takes place over the tropical indian ocean peaks in late boreal winter and early spring and persists through boreal summer our observational analysis suggests that this indian ocean warming induces robust climatic anomalies in the summer indo west pacific region prolonging the el nino s influence after tropical east pacific sea surface temperature has returned to normal in response to the indian ocean warming precipitation increases over most of the basin forcing a matsuno gill pattern in the upper troposphere with a strengthened south asian high near the ground the southwest monsoon intensifies over the arabian sea and weakens over the south china and philippine seas an anomalous anticyclonic circulation forms over the subtropical northwest pacific collocated with negative precipitation anomalies all these anomaly patterns are reproduced in a coupled model simulation initialized with a warming in the tropical indian ocean mixed layer indicating that the indian ocean warming is not just a passive response to el nino but important for summer climate variability in the indo west pacific region the implications for seasonal prediction are discussed