rare earth element characteristics and k ar ages of the band ziarat ophiolite complex southeastern iran the band ziarat complex of southeastern iran is located on the western boundary c f the jaz murian depression rand is bounded by two ma jar fault systems the principal rock units of this complex are a gabbro sequence that includcs low and high level cumulate gabbros a late intrusive sequence that consists of diorite and plagiogranite and a volcanic sequence that includes diabase dikes and a lesser anaount of basaltic lava mantle rocks are virtually absent because of the presence of the two bounding fault systems but we consider the complex to be an ophiolite in nature rare earth cleislcnt ree whole rock data clearly diffcremtiate the classic ophiolitic lithologies for the crustal rocks in this complex bas4 on the ree data there are two distinct types of basalt presenl at band ziarat i those that formed from an initial basaltic melt with a light rare earth element lree enriched signature similar to intraplate hasalts and ii those that have lree depleted patterns similar to normal mid ocean ridge basalts the data also suggest i that the gabbros are adcumulates and were derived from a source slightly enriched in lree with fractic natioam controlled by removal of clinopyroxene or hornblende and plagioclase and ii that the late intrusive rocks as well as a ma jority of the cliabnse dikes are cogenetic and were derived from thc same lree enriched source k ar ages ranging from 134 4 to 146 5 ma for lowlevel gabbros and from 821 4 to 930 4 ma for high level gabbros were measured on five hornblende and two whole rock samples which suggests that these rocks may have formed early in the cretaceous period

geology of the sari gunay epithermal gold deposit northwest iran the sari gunay epithermal gold deposit is located within a mildly alkaline latitic to trachytic volcanic complex in central northwest iran intrusive and volcanic rocks that host the deposit have been dated at between 11 7 and 11 0 ma with one younger sample at 8 0 ma 40ar 39ar dating of igneous biotite and hornblende whereas sericitic alteration associated with an early stage of hydrothermal activity occurred between 10 8 and 10 3 ma the best age estimate is 10 7 ma obtained by 40ar 39ar dating of sericite the main hydrothermal system was structurally localized by a diatreme breccia complex centered on the sari gunay hill earliest hydrothermal activity only encountered at depth 300 m below surface produced weak potassic alteration and quartz sulfide magnetite veining with low grades of cu and au mineralization reminiscent of shallow level 1 5 km depth porphyry gold systems paragenetically later quartz tourmaline breccias and veins followed the south southwest north northeast trend of the diatreme breccias and produced strong sericitic alteration and silicification in igneous clasts and wall rocks fluid inclusions indicate temperatures of 246 to 360 c and salinities of 34 4 to 46 1 wt percent nacl equiv in hypersaline inclusions coexisting with low density co2 bearing vapor phase inclusions these fluids do not appear to have deposited gold but the breccias provided further structural permeability for flow of later mineralizing epithermal fluids invisible gold occurs in solid solution in fine grained arsenical pyrite and minor arsenopyrite deposited in the early stages of quartz adularia pyrite stibnite veins late stage minerals in these veins include realgar orpiment cinnabar and extremely rare wire gold liquid rich fluid inclusions in these veins have an average homogenization temperature trapping temperature of 199 24 c salinities of 3 6 1 1 wt percent nacl equiv and coexist with low density co2 bearing vapor phase inclusions suggesting low pressure conditions phase separation may have been a contributory cause of gold deposition but precipitation of sulfides in response to rapid cooling of the system may have been the main control on deposition of pyrite hosted gold the sari gunay gold deposit and its host volcanic system form part of the takab belt of structurally controlled middle miocene mildly alkaline volcano plutonic complexes the sediment hosted zarshuran gold deposit located 190 km to the north northwest along the belt is also related to middle miocene magmatism the takab belt is marginally younger than and displaced to the southwest of the extensive eocene miocene urumieh dokhtar calk alkaline volcanic arc which hosts several large porphyry cu deposits e g sar cheshmeh meiduk rocks of the takab belt are also distinctly more alkaline than the urumieh dokhtar rocks viewed in the context of plate tectonic models for neogene closure of a neo tethys ocean between the afro arabian and eurasian plates these differences may reflect a normal subduction zone origin for the urumieh dokhtar arc and contained porphyry cu deposits but a collisional origin for the slightly younger takab belt volcanic rocks and epithermal gold deposits the sari gunay deposit may thus be classified as a collision related alkalic type epithermal system although it is less alkaline than classic deposits of this group such as porgera emperor or cripple creek the latter apparently being related to postcollisional or back arc extensional rather than syncollisional processes

geochemistry of central tethyan upper permian and lower triassic strata abadeh region iran nearly 2 km of upper permian to lower triassic limestones are exposed in the hambast mountain abadeh region iran lime mud matrix and most bioclasts of permian age are recrystallized into large calcite crystals and contain 600 4000 ppm sr suggesting a probable aragonite precursor low bulk rock 18 o values 7 to 10 pdb and recrystallized textures are also indicative of diagenetic alteration within the murghabian and abadehian two gradual upward increases in carbonate and organic matter 13 c compositions each roughly 3 pdb in magnitude are documented both are attributed to increased organic productivity and sequestration of organic matter in sediments within the julfian and across the permian triassic p t boundary two sharp upward decreases in carbonate and organic matter 13 c values each 4 pdb in magnitude are observed both are best explained by mixing of a deep water mass having low 13 c values and a shallow water mass having high 13 c compositions early triassic 13 c values initially low 1 pdb increase to 3 pdb within 100 m above the p t boundary variations in 13 c compositions of carbonate and organic matter and changes in 13 c 13 ccar 13 corg indicate that early triassic 13 c values were controlled by productivity cycles

tropical storm induced near inertial internal waves during the cirene experiment energy fluxes and impact on vertical mixing 1 near inertial internal waves niw excited by storms and cyclones play an essential role in driving turbulent mixing in the thermocline and interior ocean storm induced mixing may be climatically relevant in regions like the thermocline ridge in the southwestern indian ocean where a shallow thermocline and strong high frequency wind activity enhance the impact of internal gravity wave induced mixing on sea surface temperature the cirene research cruise in early 2007 collected ship borne and mooring vertical profiles in this region under the effect of a developing tropical cyclone in this paper we characterize the niw field and the impact of these waves on turbulent mixing in the upper ocean niw packets were identified down to 1000 m the maximum depth of the measurements we estimated an niw vertical energy flux of up to 2 5 mw m 2 within the pycnocline which represents about 10 of the maximum local wind power input a non negligible fraction of the wind power input is hence potentially available for subsurface mixing the impact of mixing by internal waves on the upper ocean heat budget was estimated from a fine scale mixing parameterization during the first leg of the cruise characterized by little niw activity the average heating rate due to mixing was 0 06 c month 1 in the thermocline 23 24 kg m 3 isopycnals during the second leg characterized by strong niw energy in the thermocline and below this heating rate increased to 0 42 c month 1 indicative of increased shear instability along near inertial wave energy pathways

enhanced wind driven downwelling flow in warm oceanic eddy features during the intensification of tropical cyclone isaac 2012 observations and theory abstracttropical cyclones tcs typically produce intense oceanic upwelling underneath the storm s center and weaker and broader downwelling outside upwelled regions however several cases of predominantly downwelling responses over warm anticyclonic mesoscale oceanic features were recently reported where the ensuing upper ocean warming prevented significant cooling of the sea surface and tcs rapidly attained and maintained major status elucidating downwelling responses is critical to better understanding tc intensification over warm mesoscale oceanic features airborne ocean profilers deployed over the gulf of mexico s eddy features during the intensification of tropical storm isaac into a hurricane measured isothermal downwelling of up to 60 m over a 12 h interval 5 m h 1 or twice the upwelling strength underneath the storm s center this displacement occurred over a warm core eddy that extended underneath isaac s left side where the ensuing upper ocean warming was 8 kw m 2 sea surface tempera

observed energy exchange between low frequency flows and internal waves in the gulf of mexico abstracta long term mooring array deployed in the northern gulf of mexico is used to analyze energy exchange between internal waves and low frequency flows in the subthermocline 245 450 m there

eastern turkish high plateau as a small turkic type orogen implications for post collisional crust forming processes in turkic type orogens abstract post collisional magmatism may be generated by extensive crustal melting in tibet type collisional environments or by falling out of slabs from under giant subduction accretion complexes in turkic type collisional orogens giving rise to decompression melting of the asthenospheric mantle replacing the removed oceanic lithosphere in turkic type post collisional magmatism the magmatic products are dominantly alkalic to peralkalic and greatly resemble those of extensional regions giving rise to much confusion especially in interpreting old collisional orogenic belts such magmatic regions are also host to a variety of economically valuable ore deposits including gold one place in the world where today active turkic type post collisional magmatism is present is the eastern anatolian high plateau produced after the terminal arabia eurasia collision in the late miocene the plateau is mostly underlain by the late cretaceous to oligocene east anatolian accretionary complex which formed south of the rhodope pontide magmatic arc this subduction accretion complex has been further shortening since the collision but it has also since been domed and became almost entirely covered by at least 15 000 km3 of volcanic rocks the volcanic rocks are calc alkalic in the north transitional in the middle and alkalic in the south of the plateau where the crust is thinnest today less than 38 km the volcanics are derived almost entirely from an enriched mantle the ages of the volcanics also become younger from north to south from about 11 ma to possibly 17th century ad we interpret the origin of the magmatic rocks as the result of decompression melting of the asthenospheric mantle sucked towards the exposed base of the east anatolian accretionary complex as the oceanic lithosphere beneath it fell out the lower density of the hot asthospheric material was the cause of the doming we believe that similar processes dominated the post collisional tectonics of such vast turkic type orogens as the altaids of central asia the late devonian early carboniferous lachlan belt in southeastern australia and the pan african collage of northeast afro arabia it is likely that archaean collisions were dominated by turkic type post collisional events rather than tibetan ones that only became common in the proterozoic

redistribution of energy available for ocean mixing by long range propagation of internal waves ocean mixing which affects pollutant dispersal marine productivity and global climate1 largely results from the breaking of internal gravity waves disturbances propagating along the ocean s internal stratification a global map of internal wave dissipation would be useful in improving climate models but would require knowledge of the sources of internal gravity waves and their propagation towards this goal i present here computations of horizontal internal wave propagation from 60 historical moorings and relate them to the source terms of internal waves as computed previously2 3 analysis of the two most energetic frequency ranges near inertial frequencies and semidiurnal tidal frequencies reveals that the fluxes in both frequency bands are of the order of 1 kw m 1 that is 15 50 of the energy input and are directed away from their respective source regions however the energy flux due to near inertial waves is stronger in winter whereas the tidal fluxes are uniform throughout the year both varieties of internal waves can thus significantly affect the space time distribution of energy available for global mixing

subsurface structure of the eastern edge of the zagros basin as inferred from gravity and satellite data a data set of 10 505 points of land gravity measurements from southeast iran obtained from the bureau gravimetrique international combined with landsat imagery was used to investigate crustal and cenozoic lithospheric structure interpretation of the bouguer anomalies reveals three primary structural features the zagros mountain belt is characterized by a progressive decrease in gravity values from 70 mgal near the persian gulf to 160 mgal over the suture zone between the arabian margin and central iran crustal blocks the second feature is marked by a backward l shaped pair of anomalies that extends from the eastern peripheries of the zagros basin and wraps around southern iranian shores these 15 to 20 km deep source anomalies with amplitudes of as much as 10 mga are interpreted as intrabasement intrusions demarcating an ancient rift axis the shallow 6 8 km east west trending anomalies are perhaps interbasement uplifts bordered by reverse faults the third structure observed on both gravity and landsat displays a north striking eastward facing topographic escarpment has a gravity gradient of 0 85 mgal km and is right laterally offset approximately 100 km by the zagros main recent fault on landsat this escarpment is manifest by a system of north trending faults that seem to diverge into a horsetail pattern toward the east and by a set of north trending dike swarms that cut jurassic volcano sedimentary rocks it separates two distinct structural and sedimentary styles the zagros foreland basin anticlines of shallow marine precambrian to pliocene rocks on the west and the makran deep water eocene flysch belt on the east a comparison of gravity features with surface structures on thematic mapper and landsat multispectral scanner imagery indicates that a northeast trending fault system is the result of post miocene pervasive transpressive stress coupled with clockwise rotation of underlying basement blocks following the collision of arabia and iran accommodation structures such as forced folds and rabbit ear anticlines may develop over and on the flanks of the basement blocks providing remigration and trapping mechanisms for new oil and gas plays

on the spatial and temporal distribution of near inertial energy in the southern ocean 1 we use an eddying realistic primitive equation model of the southern ocean to examine the spatial and temporal distribution of near inertial wind power input wpi and near inertial energy nie in the southern ocean we find that the modeled near inertial wpi is almost proportional to inertial wind stress variance iwsv while the modeled nie is modulated by the inverse of the mixed layer depth we go on to assess recent decadal trends of near inertial wpi from trends of iwsv based on reanalysis wind stress averaged over the southern ocean annual mean iwsv is found to have increased by 16 over the years 1979 2011 part of the increase of iwsv is found to be related to the positive trend of the southern annular mode over the same period finally we show that there are horizontal local maxima of nie at depth that are almost exclusively associated with anticyclonic eddies

advective spreading of storm induced inertial oscillations in a model of the northwest atlantic ocean the spreading of inertial oscillations induced by the passage of hurricane juan 2003 across the gulf stream and the scotian shelf is examined using a regional model of the northwest atlantic ocean it is found that surface intensified inertial oscillations develop at locations remote from the storm track after a period of 5 10 days a diagnostic technique reveals the importance of advection by the background geostrophic flow for explaining this effect the results suggest that advection by mean circulation can play a role in redistributing near inertial energy in the ocean we argue that advective redistribution could have important consequences for understanding diapycnal mixing in the ocean

structures in southwest asia and evolution of the eastern tethys abstract southwest asia comprises the following 1 a two major orogenic belts a northern belt derived from the paleo tethys and a southern belt derived from the neo tethys 2 b minor orogenic belts derived from neo tethyan marginal basins 3 c continental blocks that originated from gondwana by splitting and stripping and subsequently drifted and collided with continental asia in its process of construction and 4 d residual oceanic basins which are assumed as being not yet closed neo tethyan marginal basins the entire region appears as the product of tethyan evolution

kinematics of a sigmoidal fold and vertical axis rotation in the east of the zagros makran syntaxis southern iran paleomagnetic magnetic fabric and microtectonic approaches abstract the zagros simple fold belt is characterized by elongated curved or sigmoidal folds the trend of these structures together with the structural style change suddenly across the zagros makran syntaxis which separates the continental collision domain of zagros from the oceanic subduction one in makran this work focuses on the minab anticline outcropping in the easternmost part of zagros in order to understand the kinematics of a sigmoidal fold and underscore possible vertical axis rotations in the eastern side of the syntaxis we performed a joint study of magnetic fabric microtectonics and paleomagnetism of the northern termination of this fold the two limbs have been sampled 7 sites 134 samples along three cross sections corresponding to three different orientations of the fold axis the rocks are weakly deformed fine grained mio pliocene reddish siltstones the shortening directions deduced from both magnetic fabric analysis and microtectonic observations are consistent with each other they are horizontal and roughly perpendicular to the local fold axis following the torsion of the fold hinge line and indicating a tectonic origin of the magnetic fabric rockmagnetic analyses thermomagnetic curves hysteresis loops point to the presence of magnetite in the psd and md ranges as the main magnetic carriers together with a minor contribution from hematite apart from a post tilting sub actual vrm and or crm component a paleomagnetic analyses yield mainly two pre tilting magnetization components component b is carried by magnetite spanning the intermediate to high unblocking temperature range 300 c t ubs 580 c component c has unblocking temperatures characteristic of hematite 580 c t ubs 680 c both are ante folding based on positive reversal and fold tests inside each of the cross section but also for the three sections together however because component c is biased by some inclination flattening only component b is taken into account afterwards after full tectonic correction the site mean direction of component b calculated for 6 out of the 7 sites is not statistically different from the individual site mean directions the intersection direction determined by small circle analysis in these six sites is d 18 0 i 33 7 k 482 alpha 95 2 6 compared to the mio pliocene direction expected in this area for africa it corresponds to an overall clockwise rotation of the whole structure of some 18 3 5 1 consistent with the regional geodynamic context the absence of differential paleomagnetic rotation from one cross section to the other and the fact that the magnetic lineation together with the shortening direction deduced from microtectonic analysis follows the fold curvature demonstrate that the torsion of this fold is not secondary but rather coeval with the fold amplification the torsion of the fold would stem from underlying inherited mesozoic structures and the rheological response during the deformation of two incompetent decollement layers undergoing differential velocities and a change of thickness in a constant stress field direction

propagation of wind energy into the deep ocean through a fully turbulent mesoscale eddy field abstract the authors analyze the 3d propagation of wind forced near inertial motions in a fully turbulent mesoscale eddy field with a primitive equation numerical model although the wind stress is uniform the near inertial motion field quickly becomes spatially heterogeneous involving horizontal scales much smaller than the eddy scales analysis confirms that refraction by the eddy relative vorticity is the main mechanism responsible for the horizontal distortion of the near inertial motions which subsequently triggers their vertical propagation an important result is the appearance of two maxima of near inertial vertical velocity both with rms values reaching 40 m day 1 one at a depth of 100 m and another unexpected one much below the main thermocline around 1700 m the shallow maximum captured by the highest vertical normal modes involves near inertial motions with a spatial heterogeneity close to the eddy vorticity gradient field these characteristics match analytical results obtained with y

plate tectonics and orogenic research after 25 years a tethyan perspective abstract orogeny the process by which the earth s prominent mountain ranges are constructed has been a central topic of interest in the earth sciences since at least the end of the 18th century the recognition that strains and displacements of very considerable magnitude occur along all of the three dimensions within an orogenic belt during its evolution has grown gradually during the last two centuries emphasis on primary vertical movements dominated the ideas on the nature of orogeny during the first half of the 19th century whereas compression and consequent uplift across mountain belts were believed to be the main cause for their origin during the subsequent one hundred years or so that were spent under the dominance of the fixist contraction theory mobilist tectonicians realised that continental drift in places also required motion along the trend of orogenic belts but this view did not gain general acceptance recognition of significant strike slip motion parallel or subparallel with mountain ranges evolved independently and mostly within the fixist camp by the 1960 s presence of important motions both along and across mountain belts had become common knowledge but no theoretical basis existed to account for them all

improved global maps and 54 year history of wind work on ocean inertial motions 1 the global distribution and 54 year time dependence of the energy flux from the wind to near inertial motions is computed by driving a slab mixed layer model with ncep ncar reanalysis winds improving upon previous estimates alford 2001 watanabe and hibiya 2002 the slab model is solved spectrally with frequency dependent damping the resulting solutions are more physically sensible than the previous and more skillful at high latitudes where the inertial frequency approaches the 4 daily sampling of the reanalysis winds this enables alford s calculation whose domain was limited to 50 to be extended to the poles the high latitude reliability is demonstrated by direct comparison with a high resolution regional model remo in the ne atlantic the total power input 0 47 tw has increased by 25 since 1948 paralleling observed increases in extratropical cyclone frequency and intensity if believable the trend may have important consequences for modulation of the meridional overturning circulation

effect of typhoon kalmaegi 2014 on northern south china sea explored using muti platform satellite and buoy observations data abstract based on observational data from a buoy mooring array and satellite remote sensing data for sea surface winds temperature and height during the passage of typhoon kalmaegi 2014 a systematic analysis is performed on the atmospheric and oceanic variables of winds sea level air pressure surface air temperature sensible and latent heat fluxes rainfall water temperature salinity and ocean currents kalmaegi passed through the south china sea scs with a mean non dimensional speed of 2 87 typical of a fast moving storm with a predominantly baroclinic oceanic response in addition to some well documented response features such as rightward biased intensifications in sea surface cooling and currents a much deeper mixed layer to the right side of the storm and a strong near inertial oscillation in the thermocline we here identify several new features as follows 1 the current velocity to the right side of the track decays faster than that to the left side 2 on the right side of the track the typhoon induced water temperature anomaly exhibits a three layered cooling warming cooling structure in the vertical with salinity and density anomaly profiles sharing a similar pattern 3 on the left side of the track the whole upper ocean is cooled whereas salinity shows no variation in the uppermost 20 m layer with a negative anomaly for water at depths from 20 to 50 m and a positive anomaly below 50 m the associated mechanisms are discussed in the text 4 the storm induced maximum cooling is not unique to kalmaegi 2014 in fact storms with tracks similar to that of kalmaegi 2014 may induce similar maximum cooling in the northern scs which may be useful in predictions of where such storms would induce the maximum cooling

controls on terrigenous sediment supply to the arabian sea during the late quaternary the makran continental slope the input of terrigenous sediment along the tectonically active makran continental margin off south western pakistan gulf of oman northern arabian sea is studied on the basis of sediment cores distributed along a transect from the upper slope to the abyssal plain spatial and temporal variations in sediment composition sedimentation rate and turbidite frequency in late pleistocene holocene time last 20 14c ka will be discussed and related to changes in sea level and climate and tectonic activity end member modelling of the grain size distributions of the hemipelagic and turbiditic sediments indicate that the sediments are adequately described as mixtures of three end members which represent turbidite sand turbidite silt or eolian dust and fluvial mud the geochemical and mineralogical compositions of the hemipelagic sediments indicate that the eolian dust was dominantly supplied from the northern arabian peninsula and the persian gulf region and that the fluvial input is from the makran margin the ratio of contributions of eolian and fluvial sediment in the hemipelagic intervals is used as an indicator of continental aridity i e summer monsoon intensity highest holocene turbidite frequencies and sedimentation rates are recorded at the deepest coring sites they are related to the proximity of the deformation front of the accretionary prism turbidite sedimentation on the upper continental slope was most frequent during the last glacial period of sea level lowstand and continued during the entire deglaciation and sea level rise infrequent turbidite sedimentation occurred during the holocene highstand of sea level turbidite sedimentation during the period of late sea level rise and the holocene sea level highstand is inferred to be due to the strong impact of episodic events i e flash floods and earthquakes and because of the narrow shelf of the active makran continental margin

geochemical characteristics 40ar 39ar ages and original tectonic setting of the band e zeyarat dar anar ophiolite makran accretionary prism s e iran abstract the makran accretionary prism in southeastern iran contains extensive mesozoic zones of melange and large intact ophiolites representing remnants of the tethys oceanic crust that was subducted beneath eurasia to the north of the makran accretionary prism lies the jaz murian depression which is a subduction related back arc basin the band e zeyarat dar anar ophiolite is one of the ophiolite complexes it is located on the west side of the makran accretionary prism and jaz murian depression and is bounded by two major fault systems the principal rock units of this complex are a gabbro sequence which includes low and high level gabbros an extensive sheeted diabase dike sequence late intrusive rocks which consist largely of trondhjemites and diorites and volcanic rocks which are largely pillow basalts interbedded with pelagic sedimentary rocks including radiolarian chert chondrite and primitive mantle normalized incompatible trace element data and age corrected nd pb and sr isotopic data indicate that the band e zeyarat dar anar ophiolite was derived from a midocean ridge basalt like mantle source the isotopic data also reveal that the source for basalts was indian ocean type mantle based on the rare earth element ree data and small isotopic range all the rocks from the band e zeyarat dar anar ophiolite are cogenetic and were derived by fractionation from melts with a composition similar to average e morb fractionation was controlled by the removal of clinopyroxene hornblende and plagioclase three 40ar 39ar plateau ages of 140 7 2 2 142 9 3 5 and 141 7 1 0 ma and five previously published k ar ages ranging from 121 4 to 146 5 ma for the hornblende gabbros suggest that rocks from this ophiolite were formed during the late jurassic early cretaceous plate reconstructions suggest that the rocks of this complex appear to be approximately contemporaneous with the masirah ophiolite which has crystallization age of 150 ma like masirah the rocks from the band e zeyarat dar anar ophiolite complex represent southern tethyan ocean crust that was formed distinctly earlier than crust preserved in the 90 100 ma bitlis zagros ophiolites including the samail ophiolite

wind ringing of the ocean in presence of mesoscale eddies 1 recent findings have highlighted the impact of high frequency hf winds on the inertial motions and the consequences on the large scale oceanic circulation wunsch and ferrari 2004 within this context the present study focuses on the role of intermediate scales related to oceanic mesoscale eddies results show that a turbulent eddy field does not affect the impact of hf winds on the inertial motions however the eddies efficiently and permanently concentrate the wind forced inertial motions in small scale anticyclonic structures this leads to a spatially heterogeneous vertical mixing strongly related to the eddy field properties

biostratigraphic zonation and 40ar 39ar ages for the neotethyan khoy ophiolite of nw iran abstract the khoy ophiolite in northwestern iran represents a piece of oceanic lithosphere formed in the mesozoic neotethys this ophiolite consists from bottom to top of well defined basal metamorphic rocks peridotites gabbros and a variety of upper to lower cretaceous deep marine rocks these include pelagic fossiliferous carbonates and basalts as interlayers or exotic blocks four hornblende separates from gabbros and amphibolites give values from 108 to 111 ma the results from microfossil studies show the presence of late cretaceous e g marginotruncana globotruncana and middle to late eocene e g globorotalia orbulonoides planktonic foraminifera the data suggest that although the initial rifting and crystallization of the oceanic crust of the khoy ophiolite began in the late albian the volcanic activities continued through to the late eocene time another possibility for such variation of lithofacies and biofacies and disturbances in the fossil record may be the result of bioturbation and transportation and rapid changes of depositional conditions during eruption of the basaltic lava flows pelagic sediments alone have been listed and of the foraminiferas the first three are planktonic as would be expected only orbulonoides is a benthic form and aberrant the third possibility is that the khoy ophiolite may represent a classic supra subduction type ophiolite where volcanic members of the different parts of oceanic environment e g morb volcanic arc ocean island are now juxtaposed

interactions between near inertial mixed layer currents and the mesoscale the importance of spatial variabilities in the vorticity field abstract satellite tracked mixed layer drifter data from the 1987 ocean storms experiment in the northeast pacific are used to study the temporal and spatial variability in the near inertial currents of the surface mixed layer the data suggest that the near inertial currents interact with the mesoscale vorticity to explore the exact nature of this relationship an asymptotic analysis is extended to include the mesoscale and it is shown that not only gradients in the planetary vorticity but also the gradients in the mesoscale vorticity affect the generation and evolution of near inertial mixed layer currents while the effect is relevant for the large scale evolution of the near inertial currents the vorticity gradients of the mesoscale field determine the local behavior of near inertial currents using a three dimensional model it is shown that areas of large gradients in the mesoscale vorticity coincide with areas of low near inertial energy the smaller spatial scales in the near inertial energ

high tio 2 metadiabase dikes of the hudson highlands new york and new jersey possible late proterozoic rift rocks in the new york recess

wind induced motion in the vicinity of a bottom density front response to forcing frequency 1 a numerical model is used to examine the influence of nonlinear processes in the vicinity of a shallow sea bottom density front upon the depth of penetration of the wind s momentum at both superinertial and subinertial frequencies calculations show that nonlinear effects associated with differences in vorticity across the frontal jet significantly influence the depth of penetration of the wind s momentum and internal wave propagation differences in wind induced current amplitude and phase at depth due to nonlinear effects give rise to substantial vertical velocity in the frontal region which drives near bed currents and forces internal waves at superinertial frequencies internal waves propagate away from the positive vorticity side of the front however at depth internal waves are generated and current amplitude increases in the region of sloping density surfaces associated with the front on the negative vorticity side due to an effective inertial frequency below inertial the wind s energy can propagate deeper into the water column wind forcing at subinertial frequencies does not lead to internal wave propagation on the positive vorticity side of the front the wind s momentum cannot diffuse to depth due to turbulence suppression by stable stratification the ability of the wind s momentum to penetrate to a greater depth in a frontal region through nonlinear effects suggests that these may be important processes influencing wind mixing in frontal regions

latitudinal dependence of wind induced near inertial energy midlatitudestorms accountingforthemajorityof windenergyinputtonear inertialmotionsintheocean are known to shift their track significantly from one year to another the consequence of such storm track shifts on wind inducednear inertialenergy nie isyetunknown here thelatitudinaldependenceofwind inducednie isfirstanalyzedintheframeworkoftheslabmodelandthentestedusingtwonumericaloceanmodels itisfound that the nie input by pure inertial wind stress forcing which dominates the wind energy input to near inertial motions is independent of latitude as a consequence the nie generated by white noise wind stress forcing is also latitudinally independent in contrast the nie generated by red noise wind stress forcing shows strong dependence on latitude owing to longer inertial periods at lower latitudes capable of sampling greater inertial wind stress forcing given that the observed surface wind stress spectra are red results from this study suggest that an equatorward shift of the storm track is likely to result in an increase in wind induced nie in the ocean while the opposite is true for a poleward shift

role of near inertial internal waves in subthermocline diapycnal mixing in the northern gulf of mexico abstractmoored adcp data collected in the northern gulf of mexico are analyzed to examine near inertial internal waves and their contribution to subthermocline diapycnal mixing based on a finescale parameterization of deep ocean mixing the focus of the study is on the impact of near inertial internal waves generated by an extreme weather event that is hurricane katrina and by month to month variation in weather patterns on the diapycnal mixing the inferred subthermocline diapycnal mixing exhibits pronounced elevation in the wake of katrina both the increased near inertial 0 8 1 8f where f is the coriolis frequency and superinertial 1 8f shear variances contribute to the elevated diapycnal mixing but the former plays a more dominant role the intense wind work on near inertial motions by the hurricane is largely responsible for the energetic near inertial shear variance energy transfer from near inertial to superinertial internal waves however appears to play an important role in elevating th

wind induced mixing in the north pacific abstracttemporal variability of the winter input of wind energy flux wind power and its relationship to internal wave fields were examined in the north pacific the dominant long term variability of the wind power input estimated from a mixed layer slab model was inferred from an empirical orthogonal function analysis and it was found that variability partly corresponded to the strength and movement of the aleutian low responses of the internal wave field to the input of wind power were examined for two winters with a meridional float array along 170 w at a sampling interval of 2 dbar time series of the vertical diffusivities inferred from density profiles were enhanced during autumn and winter after comparing diffusivities inferred from densities sampled at 2 and 20 dbar intervals argo floats with a vertical resolution of 20 dbar were used to detect spatial and temporal variability of storm related mixing between 700 and 1000 dbar in the north pacific over a period of 10 years horizontal maps

permian triassic boundary interval in the abadeh section of iran with implications for mass extinction part 1 sedimentology the uppermost permian strata of the abadeh section in iran consist of 56 m of skeletal limestone abadehian that grades upward into 18 m of grey bioturbated lime mudstone djulfian which in turn grades upward to 18 m of red nodular wackestone dorashamian containing an abundant pelagic fauna the overlying lowermost triassic includes two enigmatic layers at its base immediately above the boundary is a 1 m thick layer of inorganically precipitated synsedimentary carbonate cement the cement is composed of 10 20 cm long crystals oriented either perpendicular to the bedding or as dome shaped features resembling botryoids about 0 5 m of wackestone overlies the cement layer the second layer is a 1 5 m thick grainstone overlying the cement horizon and consists of recrystallised spherical grains ooids or peloids the remainder of unit a is composed of 100 m of grey bioturbated to nodular lime mudstone the lithofacies succession of the uppermost permian is interpreted to represent deposition under increasing water depth related to rising of relative sea level which led to drowning of the carbonate platform to below storm wave base sedimentologic characteristics lithology wide distribution and slow sedimentation rates indicate that strata immediately below the permian triassic p t boundary dorashamian interval were deposited in deep oxygenated waters the enigmatic lowermost triassic synsedimentary carbonate cement and grainstone layers are interpreted to have been deposited in shallow waters indicating a rapid and major drop in relative sea level at the end of permian time in this area followed by a relative sea level rise during the earliest triassic precipitation of synsedimentary cement immediately above the p t boundary in iran and elsewhere south china suggests a global change in ocean chemistry one possible explanation is that dissolved calcium and bicarbonate concentrations in seawater increased sufficiently to promote spontaneous carbonate precipitation a rare event in the phanerozoic but common during precambrian time alternatively a massive heating event could have resulted in co2 degassing and decreases in oceanic carbonate solubility both leading to inorganic synsedimentary carbonate precipitation inorganic precipitation of synsedimentary carbonate cement may indicate that biochemical production of carbonate was halted due to the p t boundary events our study indicates that shallow and moderately deep waters during the latest permian were well oxygenated in the open ocean setting of the central tethys sea in iran therefore p t mass extinction scenarios that invoke upon widespread marine anoxia should be viewed with caution

penetration of wind generated near inertial waves into a turbulent ocean abstractan idealized storm scenario is examined in which a wind generated inertial wave interacts with a turbulent baroclinic quasigeostrophic flow the flow is initialized by spinning up an eady m

near inertial ocean response to tropical cyclone forcing on the australian north west shelf the regional ocean modeling system roms was applied to the australian north west shelf nws to hindcast the ocean response to four intense historical tropical cyclones tcs while the four cyclones had very different trajectories across the nws all passed within 150 km of a long term vertical mooring located on the continental shelf in 125 m depth the observed ocean response at this relatively shallow southern hemisphere shelf site was characterized by the development of a peak in the counter clockwise ccw near inertial kinetic energy mixed layer deepening and subsequent restratification strong near inertial isotherm oscillations were also observed following two of the cyclones roms reproduced these features and also showed that the peak in the near inertial ccw kinetic energy was observed on the left side of each cyclone trajectory the time rate of change of near inertial kinetic energy depended strongly on the storm rossby number i e defined based on the storm speed the storm length scale and the coriolis frequency the shallow water depth on the nws resulted in first a more rapid decay of near inertial oscillations than in the deep ocean and second a generation efficiency the ratio of near inertial power to the rate of wind work of up to 10 smaller than found for cyclones propagating across deeper water the total energy put into near inertial motions is nevertheless large compared to the background tidal energy the rapid decay of near inertial motions emphasizes the importance of frictional effects in characterizing the response to cyclone forcing in shallow seas

seasonal variation of turbulent diapycnal mixing in the northwestern pacific stirred by wind stress 1 profiles of potential density obtained from ctd measurements along the northwestern pacific section at 137 e are used to estimate both mean and seasonal variations of turbulent diapycnal mixing based on both a thorpe scale method and a finescale parameterization method in general away from the bottom the estimated mean value along this section is about o 10 4 m2 s indicating much stronger mixing in the northwestern pacific than in the stratified mid latitude interior ocean it is further found that the diffusivity can even exceed 10 4 m2 s around the rough topography the turbulent diapycnal mixing in the upper ocean also displays a distinct seasonal variation with the amplitude decreasing with depth bearing a statistically significant correlation with surface wind stress forcing our study here provides evidence for the important role of energy input from wind stress in sustaining the deep ocean mixing

petrogenesis of late cretaceous lava flows from a ceno tethyan island arc the raskoh arc balochistan pakistan abstract the raskoh arc is about 250 km long 40 km wide and trends in an ene direction the oldest rock unit in the raskoh arc is an accretionary complex early to late jurassic which is followed in age by kuchakki volcanic group the most wide spread unit of the raskoh arc the volcanic group is mainly composed of basaltic to andesitic lava flows and volcaniclastics including agglomerate volcanic conglomerate breccia and tuff with subordinate shale sandstone limestone and chert the flows generally form 3 15 m thick lenticular bodies but rarely reach up to 300 m they are mainly basaltic andesites with minor basalts and andesites the main textures exhibited by these rocks are hypocrystalline porphyritic subcumulophyric and intergranular the phenocrysts comprise mainly plagioclase an 30 54 in nok chah and an 56 64 in bunap they are embedded in a micro cryptocrystalline groundmass having the same minerals apatite magnetite titanomagnetite and hematite occur as accessory minerals major trace and rare earth elements suggest that the volcanics are oceanic island arc tholeiites their low mg 42 56 and higher feo total mgo 1 24 2 67 ratios indicate that the parent magma of these rocks was not directly derived from a mantle source but fractionated in an upper level magma chamber the trace element patterns show enrichment in lile and depletion in hfse relative to n morb their primordial mantle normalized trace element patterns show marked negative nb anomalies with positive spikes on k ba and sr which confirm their island arc signatures slightly depleted lree to flat chondrite normalized ree patterns further support this interpretation the zr versus zr y and cr versus y studies show that their parent magma was generated by 20 30 melting of a depleted mantle source the trace elements ratios including zr y 1 73 3 10 ti zr 81 59 101 83 ti v 12 39 30 34 la yb n 0 74 2 69 ta yb 0 02 0 05 and th yb 0 11 0 75 of the volcanics are more consistent with oceanic island arcs rather than continental margin arcs it is suggested that the raskoh arc is an oceanic island arc which formed due to the intra oceanic convergence in the ceno tethys during the late cretaceous rather than constructed on the southern continental margin of the afghan block as claimed by previous workers it is further suggested that the semail zagros chagai raskoh muslim bagh and waziristan island arcs were developed in a single but segmented cretaceous ceno tethyan convergence zone

enhanced vertical propagation of storm induced near inertial energy in an eddying ocean channel model the interaction between inertial oscillations generated by a storm and a mesoscale eddy field is studied using a southern ocean channel model it is shown that the leakage of near inertial energy out of the surface layer is strongly enhanced by the presence of the eddies with the anticyclonic eddies acting as a conduit to the deep ocean given the ubiquity of the atmospheric storm tracks a source of near inertial energy for the ocean and regions of strong ocean mesoscale variability we argue that this effect could be important for understanding pathways by which near inertial energy enters the ocean and is ultimately available for mixing

modulation of near inertial oscillations by low frequency current variations on the inner scotian shelf abstractnear inertial oscillations nios on the inner scotian shelf are studied using observations a simple slab model and two operational shelf circulation models high frequency radar and adcp

observed upper ocean response to typhoon megi 2010 in the northern south china sea typhoon megi passed between two subsurface moorings in the northern south china sea in october 2010 and the upper ocean thermal and dynamical response with strong internal tides present was examined in detail the entire observed water column 60 360 m was cooled due to strong ekman pumped upwelling up to 50 m in the thermocline by megi with maximum cooling of 4 2 c occurring in thermocline a relatively weak maximum amplitude of 0 4 m s 1 and quickly damped e folding time scale of 2 inertial periods near inertial oscillation nio was observed in the mixed layer power spectrum and wavelet analyses both indicated an energy peak appearing at exactly the sum frequency fd1 with maximum amplitude up to 0 2 m s 1 of nio f and diurnal tide d1 indicating enhanced nonlinear wave wave interaction between f and d1 during and after typhoon numerical experiments suggested that energy transfer from nio to fd1 via nonlinear interaction between f and d1 may have limited the growth and accelerated the damping of mixed layer nio generated by megi the occurrence of fd1 had a high correlation with nio the vertical nonlinear momentum term associated with the vertical shear of nio and vertical velocity of d1 or vertical shear of d1 and vertical velocity of nio was more than 10 times larger than the horizontal terms and was responsible for forcing fd1 after megi surface layer diurnal energy was enhanced by up to 100 attributed to the combined effect of the increased surface layer stratification and additional megi forced diurnal current

a giant catastrophic mud and debris flow in the miocene makran we challenge the former interpretation of the sedimentary me lange of the makran accretionary complex as a tectonic me lange diapirically emplaced from below and provide evidence for its sedimentary gravitational emplacement from the north during tortonianmessinian times between 11 8 and 5 8 ma it is an olistostrome that includes blocks of ophiolites and oceanic sediments derived from the coloured me lange to the north and reworked chunks of the turbidites on which it rests with an erosional truncation the chaotic scattering of blocks of any size and lithology and the weak soft sediment deformation of the matrix argue against a tectonic emplacement of the chaotic formation its size and internal structure together with the size of the individual blocks make the olistostrome a fossil equivalent of the large gravitationally emplaced debris flows observed along present day continental margins and unstable volcanic edifices

the chagai porphyry copper belt baluchistan province pakistan although porphyry copper gold mineralization in the region has been known for approximately 40 years the chagai belt has only recently revealed its true potential with the discovery of a world class deposit at h14 h15 at reko diq the 300 km long east west trending chagai belt comprises several superimposed magmatic arcs and corresponding porphyry copper gold molybdenum mineralization generated in consecutive events at 43 to 37 ma middle late eocene 24 to 22 ma early miocene 18 to 16 ma early miocene 13 to 10 ma middle miocene and 6 to 4 ma late miocene early pliocene the tectonomagmatic evolution of the region was marked by major continental scale events associated with 1 the northward drift of india and its interaction and final collision with the southern margin of eurasia and 2 the collision of arabia with central iran resulting in final closure of the neo tethyan ocean initial precollisional stages of arc evolution between the middle jurassic and paleocene formed kilometer thick submarine volcanic sequences with important flyschlike packages and intercalations of biohermal limestone the subalkaline basalt and basaltic andesite of this stage possess a tholeiitic lineage of oceanic island arc affiliation small scale submarine volcanogenic copper mineralization of manto and kuroko type formed during the late mature stages of this arc just prior to collision early contact of the leading edge of india and the island arcs in the late paleocene 55 ma resulted in a reorganization of the arc in the chagai belt with the consequent extrusion of subaerial andesite followed by emplacement of magnetite series calc alkaline composition batholiths during the late eocene this plutonism accompanied the first manifestations of porphyry type alteration and mineralization at 43 ma in a rapidly emerging arc of andean type the belt is defined by 48 porphyry systems with copper gold molybdenum mineralization associated with calc alkaline biotite and amphibole bearing porphyry stocks of predominantly quartz diorite to granodiorite composition hydrothermal alteration includes potassic propylitic sericite clay chlorite sericitic and advanced argillic assemblages the last in transitional epithermal environments calcic potassic assemblages are developed locally at the expense of more mafic commonly dioritic rocks widespread porphyry copper and copper gold mineralization during the miocene at 24 to 22 and 18 to 16 ma formed in a subaerial subvolcanic environment during moderate tectonic uplift most notably during the early miocene at saindak and tanjeel faster rates of regional uplift and exhumation in conjunction with a period of conspicuous volcanic quiescence characterized large scale porphyry copper gold mineralization at h14 h15 at reko diq during the middle miocene between 13 and 10 ma regional tectonically triggered uplift and consequent exhumation may have been the result of collision of arabia with central iran in general mature cumulative supergene enrichment and oxidation zones seem to be absent in the porphyry copper deposits of the chagai belt primarily due to the high neutralization potentials and low pyrite contents of the ore related potassic alteration nevertheless a supergene chalcocite blanket formed at tanjeel during the pliocene at 4 ma in sericitic alteration that accompanied the hypogene mineralization the tectonomagmatic characteristics of the chagai porphyry copper belt including the multimillion year history of subduction along an andean type margin together with conspicuous short lived contraction events and concomitant volcanic quiescence during arc construction and evolution are similar to those in contractional belts at convergent margins containing large scale porphyry copper deposits elsewhere superposition of the chagai magmatic arcs and corresponding porphyry copper events occurred during the last 55 m y a situation that implies that the focus of magma generation above the subducting slab remained essentially stationary possible mechanisms responsible for this include seaward migration of the trench axis during much of the tertiary especially since the oligocene and consequent flattening of the subducted slab

spreading of near inertial energy in a 1 12 model of the north atlantic ocean near inertial energy in the ocean is thought to be redistributed by s dispersion whereby near inertial waves generated at the surface by wind forcing propagate downward and equatorward in this letter we examine the spreading of near inertial energy in a realistic 1 12 model of the north atlantic driven by synoptically varying wind forcing we find that 1 near inertial energy is strongly influenced by the mesoscale eddy field and appears to be locally drained to the deep ocean largely by the chimney effect associated with anticyclonic eddies and 2 the interior of the subtropical gyre shows very low levels of near inertial energy contrary to expectations based on the s dispersion effect

geomorphological analysis of the drainage system on the growing makran accretionary wedge abstract the morphology of six adjacent major catchments draining the onshore makran accretionary wedge in southeast iran and southwest pakistan was studied to examine how the channel pattern and the length profiles may reflect the recent and active growth of the wedge qualitative field surveys were combined with the quantitative analysis of channel steepness and concavity measured from digital elevation models these profiles were compared with modelled profiles using a stream power approach assuming homogeneously uplifting uniform rock substratum results show a distinct difference between the studied western and eastern catchments the three western rivers are in morphological equilibrium whereas the two eastern rivers exhibit profiles with prominent convexities and knickpoints thus notably diverging from equilibrium concave up shapes all the studied catchments share the same base level flow on similar lithologies and developed under uniform climate conditions therefore we interpret the morphometric differences in terms of differential rock uplift rate as a response to local tectonic activity this interpretation is consistent with both uplift rates of marine terraces along the coast of makran and the recorded seismicity the geomorphological analysis presented here extends coastal information to wide inland areas and documents longer term tectonic behaviour than the seismotectonic record hence the steeper surface slope and faster surface uplift rates recorded by the eastern catchments compared to equilibrium of the western catchments are regional long term signals relevant for a wide part of the makran accretionary wedge we attribute the regional geomorphic difference to quaternary variations in tectonic regimes that forced differential uplift rates of the wedge surface we hypothesize that the different tectonic regimes are related to different subduction rates

crustal and upper mantle structures of makran subduction zone se iran by combined surface wave velocity analysis and gravity modeling abstract the inversion of rayleigh wave group velocity dispersion curves is challenging because it is non linear and multimodal in this study we develop and test a new rayleigh wave dispersion curve inversion scheme using the shuffled complex evolution sce algorithm incorporating this optimization algorithm into the inverse procedure not only can effectively locate the promising areas in the solution space for a global minimum but also avoids its wandering near the global minimum in the final stage of search in addition our approach differs from others in the model parameterization instead of subdividing the model into a large number of thin layers we invert for thickness velocities and densities and their vertical gradients of four layers sediments upper crust lower crust and upper mantle the proposed inverse procedure is applied to non linear inversion of fundamental mode rayleigh wave group dispersion curves for shear and compressional wave velocities at first to determine the efficiency and stability of the sce method two noise free and two noisy synthetic data sets are inverted then real data for makran region in se iran are inverted to examine the usage and robustness of the proposed approach on real surface wave data in a second step we applied 3d gravity modeling based on surface wave analysis results to obtain the density structure and thickness of each layer the reason for using both types of data sets is that gravity anomaly has a bad vertical resolution and surface wave group velocities are good for placing layer limits at depth but they are not very sensitive to densities therefore using gravity data increases the overall resolution of density distribution in a final step we used again the sce method to invert the fundamental mode rayleigh wave group dispersion curves based on the gravity results gravity results like thicknesses and sediment densities have been used to constrain the limit of search space in the sce method results show a high shear and compressional velocity under the gulf of oman which reduce to the north of the makran region the moho depth of the oman gulf is about 18 28 km and it increases to 46 48 km under the taftan bazman volcanic arc the density image shows an average crustal density with maximum values under the gulf of oman decreasing northward to the makran

seasonal and spatial variations of southern ocean diapycnal mixing from argo profiling floats in the large scale ocean circulation and climate 4 6 here we use high resolution hydrographic profiles from argo floats in combination with the iridium communications system to investigate diapycnal mixing in the southern ocean we find that the spatial distribution of turbulent diapycnal mixing in the southern ocean at depths between 300 and 1 800 m is controlled by the topography by means of its interaction with the antarctic circumpolar current the seasonal variation of this mixing can largely be attributed to the seasonal cycle of surface wind stress and is more pronounced in the upper ocean over flat topography we suggest that additional highresolution profiles from argo floats will serve to advance our understanding of mixing processes in the global ocean interior the southern ocean is an important source of bottom water in the world s oceans and is a key upwelling site of deep water pointing to diapycnal mixing that is mixing across surfaces of equal density in the region as an important controlling factor of the global meridional overturning circulation moc refs 7 8 modelling studies have demonstrated that the global strength of the moc depends critically on the details of the representation of mixing processes in the southern ocean interior 9 a few existing observations 1014 in this region have revealed dramatic spatial heterogeneity in diapycnal mixing with values of diffusivity over smooth topography comparable to those in the mid latitude ocean interior of the order of 10 5 m 2 s 1 and enhanced mixing of the order of 10 4 m 2 s 1 or larger extending far from rough topography however discerning the nature of diapycnal mixing over the entire southern ocean is still a formidable challenge because of the very limited sampling of the necessary parameters in the region furthermore in general the temporal variability of diapycnal mixing remains poorly assessed and understood throughout most of the world s oceans but in some cases the causes of such variability might be reasonably straightforward to document asanexample recentanalysisofhistoricalhydrographic data reveals that the subsurface turbulent diapycnal mixing in the northwestern pacific displays a pronounced seasonal variability stirred by surface wind stress 15 the international argo program has created the first global array for observing the subsurface ocean a subset of argo floats deployed are designed to use the iridium communications system henceforth referred to as argo iridium floats and are able to provide high resolution 2m profiles that are able to resolve fine scale tens to hundreds of meters strain these floats

on the behavior of internal waves in the wakes of storms abstract the rossby adjustment process in the wake of a storm is studied with a view to finding within the context of linear theory how wave dispersion in both the vertical and meridional directions spreads energy which is initially confined entirely to the mixed layer comparisons are made between three cases 1 a periodic storm on the f plane where dispersion is purely vertical 2 a bounded storm on the f plane and 3 a bounded storm centered 2700 km from the equator on an equatorial beta plane particular attention is paid to the initial rate of loss of energy from the mixed layer and some simple formulas which work very well in the cases studied are derived these show that the rate of loss goes up when the mixed layer depth is increased and also that the rate scales as the square of the wavenumber values of the rates are sufficient to provide a major source of energy for internal waves below the mixed layer the often observed tendency for phase lines to propagate upward is found in all case

response of the deep ocean internal wave field to traveling midlatitude storms as observed in long term current measurements it has been demonstrated in a recent numerical experiment that double inertial frequency internal waves may play a crucial role in diapycnal mixing processes in the deep ocean with the energy effectively transferred across the internal wave spectrum down to small dissipation scales by nonlinear wave wave interactions hibiya et al 1998 to examine whether or not such double inertial frequency waves are actually generated in the real deep ocean current meter data from long term moorings in the northwest pacific basin are analyzed together with global sea surface wind data by incorporating the wind data into a simple damped slab model predominant inertial currents are shown to be excited in the mixed layer in the northwest pacific basin by traveling midlatitude storms during fall and winter the multiple filter analysis demonstrates that double inertial frequency waves as well as near inertial frequency waves are significantly amplified in the deep ocean internal wave field during the periods strong inertial currents are excited in the mixed layer this suggests that in addition to near inertial frequency waves double inertial frequency waves are actually excited by strong atmospheric disturbances through nonlinear effects as demonstrated in the numerical experiment by niwa and hibiya 1997 double inertial frequency waves thus excited seem to propagate over horizontal distances of the order of 1000 km from their source region while feeding their energy to the local internal wave field consistent with the theoretical prediction based on the magnitudes of group velocity and nonlinear interaction time olbers 1983

far field strain transmission and contractional step overs abstract in contractional subduction collisional settings convergence is accommodated by the formation of thin and thick skinned thrust and fold belts the transmission of such deformation over larger distances into orogenic foreland areas is influenced by the inherited rheological characteristics of continental lithosphere lateral rheological variations parallel to the strike of continental foreland areas creates contrasting geometries and sequences of deformation that interact during orogenic build up we investigate the far field transmission of strain within a continental lithosphere characterized by a laterally variable rheology through physical analogue modelling rheological weak crustal zones were introduced at distance from an advancing backstop to study the progressive along strike linkage and interference of structures during contraction the results reveal that rheologically weak crustal zones localise far field contractional deformation when the size of weak zones by means of their horizontal extend to depth ratio is large deformation localises at the boundaries of the weak zone where they lead to the formation of large offset faults subsequently the faults migrate along strike into areas that are rheologically stronger when the size of the weak zone is reduced a large scale contractional step over forms in orogenic forelands where rheologically contrasting domains transmit out of sequence deformation by a gradual migration of thrust offsets and fold amplitudes along their strike these results show that crustal scale orogenic step overs do not always reflect variations in the geometry of the plate boundary indenter or along strike gradients in shortening rates such features may also form in response to variations in rheology as the ones created by inherited extensional basins situated at large distances from plate boundaries in the orogenic foreland

the neotethyan sanandaj sirjan zone of iran as an archetype for passive margin arc transitions the sanandaj sirjan zone of iran is a northwest trending orogenic belt immediately north of the zagros suture which represents the former position of the neotethys ocean the zone contains the most extensive best preserved record of key events in the formation and evolution of the neotethys from its birth in late paleozoic time through its demise during the mid tertiary collision of arabia with eurasia the record includes rifting of continental fragments off of the northern margin of gondwanaland formation of facing passive continental margins initiation of subduction along the northern margin and progressive development of a continental magmatic arc the latter two of these events are critical phases of the wilson cycle that elsewhere in the world are poorly preserved in the geologic record because of superimposed events our new synthesis reaffirms the similarity between this zone and various terranes to the north in central iran late paleozoic rifting preserved as a type granites and accelerated subsidence was followed by a phase of pronounced subsidence and shallow marine sedimentation in permian through triassic time marking the formation and evolution of passive margins on both sides of the suture subduction and arc magmatism began in latest triassic early jurassic time culminating at 170 ma the extinction of arc magmatism in this zone and its shift northeastward to form the subparallel urumieh dokhtar arc occurred diachronously along strike in late cretaceous or paleogene time post cretaceous uplift transformed the zone from a primarily marine borderland into a marine archipelago that persisted until mid tertiary time

decadal mean impact of including ocean surface currents in bulk formulas on surface air sea fluxes and ocean general circulation abstractthe decadal mean impact of including ocean surface currents in the bulk formulas on surface air sea fluxes and the ocean general circulation is investigated for the first time using a global eddy permitting coupled ocean sea ice model although including ocean surface currents in air sea flux calculations only weakens the surface wind stress by a few percent it significantly reduces wind power input to both geostrophic and ageostrophic motions and damps the eddy and mean kinetic energy throughout the water column furthermore the strength of the horizontal gyre circulations and the atlantic meridional overturning circulation are found to decrease considerably by 10 15 and 13 respectively as a result of the weakened ocean general circulation the maximum northward global ocean heat transport decreases by about 0 2 pw resulting in a lower sea surface temperature and reduced surface heat loss in the northern north atlantic additional sensitivity model experiments further demonstrate that

sandstone detrital modes in the makran accretionary wedge southwest pakistan implications for tectonic setting and long distance turbidite transportation detrital modes of early miocene to early pliocene sandstones from the makran accretionary wedge in southwest pakistan show a mainly quartzolithic composition with an evolution from the transitional recycled to quartzose recycled the lithic types however indicate two distinct petrofacies accreted abyssal plain turbidites have qp11lvm27lsm62 and lm39lv27ls34 showing a predominant supply from sedimentary and metasedimentary source terranes whereas slope and shelf facies sediments deposited on the accretionary wedge have qp7lvm47lsm47 and lm22lv48ls30 due to an increase of volcanic detritus the detrital modes of the abyssal plain sediments suggest a recycled orogenic source probably the himalayan collision zone the facies and longitudinal dispersal pattern suggest deposition in an oligo miocene analogue of the present indus fan the sediment must have been transported across strike parallel to the transform structure linking the makran wedge to the himalayas chaman ornach nal fault system and fed into the fan at the western end of the subduction zone the detrital modes also show an increase in volcanic detritus with time lv l 0 27 for the early miocene abyssal plain sediments to 0 47 for the slope sequences this may have been derived from late mesozoic volcanic terrains in northern baluchistan or the ladakh himalayas or more probably from the early to middle miocene andesitic volcanic centre in the northern makran

surface wave effects on the wind power input to mixed layer near inertial motions abstractocean surface waves play an essential role in a number of processes that modulate the momentum fluxes through the air sea interface in this study the effects of evolving surface waves on the wind power input wpi to near inertial motions nims are examined by using momentum fluxes from a spectral wave model and a simple slab ocean mixed layer model single point numerical experiments show that without waves the wpi and the near inertial kinetic energy ni ke are overestimated by about 20 and 40 respectively globally the overestimate in wpi is about 10 during 2005 08 the largest surface wave effects occur in the winter storm track regions in the midlatitude northwestern atlantic pacific and in the southern ocean corresponding to large inverse wave age and rapidly varying strong winds a relatively low frequency of occurrence of wind sea is found in the midlatitudes which implies that the influence of evolving surface waves on wpi is intermittent occurring less than 10 of the tot

new insights into the structural model of the makran subduction zone by fusion of 3d inverted geophysical models abstract geological modeling by geophysical data in the makran subduction zone is a challenging task which comes from its extreme structural and geological complexity different geological models were presented for this zone in previous studies by the use of various sources of information among these studies numerous geophysical models were introduced to illustrate depth geometry and location of the subduction zone and definition boundaries with adjacent zones however structural complexity of the media and high degree of variation in geological units reduce accuracy of geophysical model derivation in this study an integrated strategy via model fusion for geological model building of the makran subduction zone was presented using gravity and magnetic data in the presented strategy gravity and magnetic models were integrated through fusing procedure herewith airborne magnetic and gravity data were inverted by fine gridding and solving large scale problems for each set of potential field data while magnetic model inherently was able to reveal near surface structures gravity data modeled large depth anomalies afterwards a discrete wavelet transform rule was used for fusion magnetic and gravity models to derive a unique model containing advantage of both sets of data the fused model revealed more detail of the makran zone structure location of the subduction zone and steep dip faults the final models proposed depth of 40 km for the top of the oceanic crust with variation in thickness from 5 to 8 km basin ward the subduction zone located 200 km in the onshore and it shows a very low dip

on the loss of wind induced near inertial energy to turbulent mixing in the upper ocean wind induced near inertial energy has been believed to be an important source for generating the ocean mixing required to maintain the global meridional overturning circulation in the present study the near inertial energy budget in a realistic 1 12 degrees model of the north atlantic ocean driven by synoptically varying wind forcing is examined the authors find that nearly 70 of the wind induced near inertial energy at the sea surface is lost to turbulent mixing within the top 200 m and hence is not available to generate diapycnal mixing at greater depth assuming this result can be extended to the global ocean it is estimated that the wind induced near inertial energy available for ocean mixing at depth is at most 0 1 tw this confirms a recent suggestion that the role of wind induced near inertial energy in sustaining the global overturning circulation might have been overemphasized

sandstone petrology and geochemistry of the oligocene early miocene panjgur formation makran accretionary wedge southwest pakistan implications for provenance weathering and tectonic setting abstract the oligocene early miocene panjgur formation is comprised of submarine fan and abyssal plain turbidites deposited within the makran subduction complex sandstones of the formation are litharenite to feldspathic litharenite petrographic data indicates a quartzose recycled provenance dominated by plutonic and metamorphic fragments major elements concentrations reveal a moderate level of mineralogical maturity and high values of chemical proxy of alteration cpa 88 29 coupled with a high th u ratio 9 37 which reveals intense weathering in the source area the zr nb y and th concentrations are comparable to upper continental crust ucc values and trends in th cr th co and cr zr ratios support contribution from a felsic source however enrichment in ni and cr reinforced by trends in ni co cr v v ni and y ni ratios reveals mixing of the felsic source with mafic ultramafic source terrains tectonic discrimination plots suggest continental arc to active continental margin setting this study supports the katawaz delta panjgur submarine fan model and upholds the initial southward transport of predominantly felsic detritus from the himalayan orogenic belt controlled by the chaman ornach nal transform fault system this study further adds that the bela muslimbagh ophiolites associated melanges and the west pakistan fold thrust belt from the east and the chagai raskoh volcanic arc from the west were also concurrently shedding mafic ultramafic detritus to the basin and that the depositional system in the makran region turned westward roughly parallel to the present active margin of the makran accretionary wedge

the response of quasigeostrophic oceanic vortices to tropical cyclone forcing abstractthe response of quasigeostrophic qg oceanic vortices to tropical cyclone tc forcing is investigated using an isopycnic ocean model idealized oceanic currents and wind fields derived from observational data acquired during hurricane katrina are used to initialize this model it is found that the upwelling response is a function of the curl of wind driven acceleration of oceanic mixed layer oml currents rather than a function of the wind stress curl upwelling downwelling regimes prevail under the tc s eye as it translates over cyclonic anticyclonic qg vortices oml cooling of 1 c occurs over anticyclones because of the combined effects of downwelling instantaneous turbulent entrainment over the deep warm water column weak stratification and vertical dispersion of near inertial energy by contrast oml cooling of 4 c occurs over cyclones due to the combined effects of upwelling instantaneous turbulent entrainment over regions of tight vertical thermal gradients strong stratificati

accommodation of arabia eurasia convergence in the zagros makran transfer zone se iran a transition between collision and subduction through a young deforming system 1 at iranian longitude the arabian plate is moving northward relative to eurasia 20 mm yr 1 according to gps to the east this relative motion is accommodated by northward subduction under the e w makran emerged accretionary prism to the west it is accommodated partly by the zagros fold and thrust belt and partly by the alborz kopet dagh deforming zones further north this work investigates the nnw striking transition zone that connects zagros and makran the minab zendan fault system satellite images and structural and geomorphic field observations show a distributed deformation pattern covering a wide domain five north to nw trending major faults were identified they exhibit evidence for late quaternary reverse right lateral slip and correspond to two distinct fault systems the western one transferring the zagros deformation to the makran prism and the eastern one northward transferring the deformation to the alborz kopet dagh tectonic study and fault slip vector analyses indicate that two distinct tectonic regimes have occurred successively since the miocene within a consistent regional ne trending compression 1 an upper miocene to pliocene tectonic regime characterized by partitioned deformation between reverse faulting and en echelon folding 2 a ne trending 1 axis transpressional regime homogeneously affecting the region since upper pliocene the change is contemporaneous with major tectonic reorganization regionally recorded therefore this study provides evidence for active deformation that is not localized but distributed across a wide zone it accommodates the convergence and transfers it from collision to subduction by transpressional tectonics without any partitioning process in the present day period

detrital zircon and provenance analysis of late cretaceous miocene onshore iranian makran strata implications for the tectonic setting a multidisciplinary provenance study including sandstone framework heavy mineral analysis in situ u pb dating of detrital zircon and hf isotopic ratio analysis of dated zircons was undertaken on late cretaceous miocene deep marine turbiditic and deltaic sandstones of makran accretionary wedge se iran to determine their sedimentary provenance and tectonic setting sandstone framework modes reveal both magmatic arc rocks as a source of late cretaceous oligocene detritus and recycling of miocene sandstones heavy mineral assemblages cr spinel and blue amphibole indicate ophiolite and high pressure low temperature metamorphic rocks blueschists as a supplementary provenance in total 2931 laser ablation inductively coupled plasma mass spectrometry icp ms u pb detrital zircon ages on 21 sandstone samples yielded three major age peaks at ca 167 ma 88 7 ma and 48 9 ma also 241 in situ hf isotope analyses of dated zircons provide evidence for dominantly igneous source rocks two main detrital zircon ages are identified 1 abundant middle jurassic grains with hf isotopic compositions of continental crust suggesting a rifting related magmatic provenance and 2 late cretaceous eocene grains with hf isotopic compositions of continental crust and nondepleted mantle suggesting a continental magmatic arc provenance this change in provenance is attributed to the late cretaceous convergence between arabia and eurasia

low frequency modulation of turbulent diapycnal mixing by anticyclonic eddies inferred from the hot time series profiles of potential density obtained from ctd measurements during the hawaii ocean time series hot programin thevicinityoftheislandofoahu hawaii areusedtoevaluatelow frequencyvariabilityof turbulent kinetic dissipation rates based on a finescale parameterization method a distinct seasonal cycle as well asan increasingtrendofdissipationrates is foundin the upper300 600 m thetrendis mainlydueto the much weaker diapycnal mixing in the first four years of the record that is 1988 92 in the upper 300 600 m enhanced diapycnal mixing is found under anticyclonic eddies with the mean dissipation rate about 53 larger than that under eddy free conditions the modulation of dissipation rates by anticyclonic eddies becomes more evident with increasing eddy strength the role of cyclonic eddies in modulating diapycnal mixing is almost negligible compared with that of anticyclonic eddies the mean dissipation rate under cyclonic eddies is comparable to that under eddy free conditions with a difference of less than 10 seasonality of the dissipation rates is partly modulated by the seasonal variation of anticyclonic eddies

variations in apparent mixing efficiency in the north atlantic central water abstract microstructure data from the north atlantic tracer release experiment natre are presented providing detailed profiles of the thermal variance in the upper 360 m of the canary basin for the fall and spring seasons the osborn cox model is used to compute the diffusivity kt the diffusivity for the depth range 240 340 m is found to be 1 0 0 04 10 5 m2 s 1 in the fall and 2 2 0 1 10 5 m2 s 1 in the spring in good agreement with dye inferred diffusivities at similar depths measured turbulent kinetic energy tke dissipation rates were found to be contaminated by hydrodynamic noise so the osborn dissipation method was not used to compute k however data segments for which the tke dissipation rate e was large enough to be unaffected by noise were used to compute the apparent mixing efficiency d the computed d values are used to investigate variations in apparent mixing efficiency with respect to density ratio r and turbulence reynolds number e n2 in an attempt to eluci

impact of synoptic atmospheric forcing on the mean ocean circulation abstractthe impact of synoptic atmospheric forcing on the mean ocean circulation is investigated by comparing simulations of a global eddy permitting ocean sea ice model forced with and without synoptic atmospheric phenomena consistent with previous studies transient atmospheric motions such as weather systems are found to contribute significantly to the time mean wind stress and surface heat loss at mid and high latitudes owing to the nonlinear nature of air sea turbulent fluxes including synoptic atmospheric forcing in the model has led to a number of significant changes for example wind power input to the ocean increases by about 50 which subsequently leads to a similar percentage increase in global eddy kinetic energy the wind driven subtropical gyre circulations are strengthened by about 10 15 whereas even greater increases in gyre strength are found in the subpolar oceans deep convection in the northern north atlantic becomes significantly more vigorous which in turn leads to an increa

geology of the onshore makran accretionary wedge synthesis and tectonic interpretation abstract this contribution is a synthesis of studies carried out since 2004 in the makran accretionary wedge exposed in se iran these studies were intended to improve our understanding of the behaviour of accretionary wedges and of the significance of the makran wedge in the frame of tethys tectonics reassessing the stratigraphy and structure of the iranian makran has allowed distinguishing four main litho tectonic units the lithological content of these four units is briefly described to discuss the sedimentary environments which record the general filling of an oceanic basin with clastic sediments derived from the north the petrology of ophiolites exposed in the backstop region to the north of the accretionary wedge itself demonstrates the existence of an oceanic basin formed in the jurassic late cretaceous to the north of continental slivers which had separated from central iran there is petrological evidence for a subduction related magmatic arc during the late cretaceous which sourced much of the clastic material in the cretaceous lower miocene turbidites present throughout the wedge the literature survey shows that the late cretaceous to present evolution of the pakistan part of the makran fold and trust belt is in its major attributes similar to that of the iranian makran these observations and results are discussed in a tectonic model that integrates knowledge on the oman mountains on the other side of the current oman subduction

growth faults above shale seismic scale outcrop analogues from the makran foreland sw pakistan abstract the southern makran fold thrust belt pakistan displays unique outcrop examples of well exposed kilometre scale listric growth faults that displace miocene age deltaic growth strata by several hundreds of metres to kilometers the largest growth faults are counter regional landward dipping bounding major clastic depocentres exposed over areas 1000 km 2 stratal offset along these faults can exceed 1 5 km fault zone thicknesses range between ca 100 and 400 m and average fault thickness displacement ratios are around 1 10 high resolution satellite data show in unprecedented detail the faults and the stratigraphic architecture of associated growth sequences which comprise kilometre scale progradational clinoforms thick mudstone units and basinwards wedging sandstone shale deposits the true vertical thickness of the syn kinematic record is in places up to 8 km making the outcrop examples equivalent to major growth faulted successions known from seismic data of large deltas and at least an order of magnitude larger than other outcrop examples a comparison of the makran outcrops with seismic reflection examples offshore nw borneo reveals distinct similarities in the gross depocentre geometries and internal architecture the key control for growth faulting is interpreted to result from sedimentary loading with rapid sedimentary progradation causing the development of rollover synclines by differential compaction and fluid expulsion and counter regional growth faults preferentially forming on the basinward side of these synclines the data and interpretations presented can be used to assess the key parameters that contribute to the development of growth faults and growth successions above shale reinforcing structural and stratigraphic observations from seismic interpretation and modelling studies in demonstrating their occurrence in exposure

the inertial chimney the near inertial energy drainage from the ocean surface to the deep layer a three dimensional primitive equation numerical model is used to study the behavior of near inertial waves generated by surface wind stress on an plane the model is fixed depth with a rigid lid on the surface and is horizontally periodic this study shows the behaviors of the wind generated near inertial waves for four different eddies 1 a subtropical cold core eddy 2 a subtropical warm core eddy 3 a california subsurface warm core eddy and 4 the gulf stream warm core ring the mean secondary circulation generated by the wind eddy interaction has magnitude to comparable to that of the ekman current and its characteristics are determined by the relative angle between wind and current the propagation characteristics of near inertial waves are quite different depending upon the sign of the relative vorticity in a cyclonic eddy near inertial wave propagation is outward from the core of the eddy the propagation direction in an anticyclonic eddy is downward and toward the core vertically propagating waves inside the eddy are trapped above a critical layer and slowly dissipated by parameterized viscous effects the model shows that anticyclones efficiently drain near inertial energy from the surface to the deep layer below the thermocline

turbulent diapycnal mixing in the subtropical northwestern pacific spatial seasonal variations and role of eddies both spatial and seasonal variation of turbulent diapycnal mixing in the subtropical northwestern pacific are evaluated by employing a fine scale parameterization method based on profiles of potential density which are obtained from ctd measurements during our recent hydrographic surveys implemented by the china national key basic research project from 2008 to 2010 and the world ocean circulation experiment over smooth seafloor the value of diffusivity away from the boundary is comparable with the values observed in the stratified midlatitude ocean interior i e o 10 5 m 2 s 1 on the other hand enhanced diapycnal mixing i e o 10 4 m 2 s 1 or larger has been found over rough topography such as the central basin trough okidaito ridge the origin of the kuroshio current and especially luzon strait which might result from dissipation of baroclinic energy generated when barotropic tides rub over rough topography over flat bathymetry mixing is probably stirred by the wind work on near inertial motions in the upper 600 m and enhanced downward propagating energy has been found in the presence of anticyclonic eddies which points to the important role of anticyclonic eddies in enhancing the diapycnal mixing at greater depth the diffusivity also displays a distinct seasonal variation with strong weak mixing corresponding to strong weak wind input energy in winter summer which however is only confined to upper 600 m this is different from the midlatitude northwestern pacific where seasonality of diffusivity can be found at 1500 m depth