seasonal variability of sea surface height in the south china sea observed with topex poseidon altimeter data topex poseidon altimeter measurements along 16 ground tracks in the south china sea from november 1992 to october 1997 were used to observe the seasonal variability of sea surface height ssh in winter november december january and february the ssh images are generally characterized by a sea surface tilting downward toward the east high sea levels on the western side of the sea have a little monthly change and a low minus sea level peak is centered in the northeastern deep basin in spring march and april a single high sea level peak hp centered at 14 n 114 e becomes a dominant feature in summer may june july and august the ssh images show a sea surface tilting downward toward the west the hp moves from 14 n 114 e in may to the northwest of luzon island in july low sea levels are centered in the offshore of the northern and southern vietnamese coast in fall september and october the appearance of an eastward low sea level jet in the western basin between 12 and 14 n constitutes a major feature of the ssh images these results are comparable with previous results and drifter measurements

hydrothermal activity in a peculiar oceanic ridge oxygen and hydrogen isotope evidence in the xigaze ophiolite tibet china the xigaze ophiolite locally displays a 7 km thick continuous sequence which probably represents an oceanic crust formed at a slow spreading ridge it consists from top to bottom of 1 1 pillow lavas with 18o between 9 and 16 and d around 90 vs smow 2 2 rare trondjhemites 9 7 18o 13 4 and d around 75 3 3 dolerite sills and dikes with 18o between 7 0 and 9 5 and d between 77 and 40 4 4 isotropic gabbros occurring as screens of the sills and dikes and rare layered gabbros these gabbros have 18o between 4 8 and 11 0 and d around 65 and bear high 18o albitized plagioclases 18o 10 which coexist with clinopyroxenes of mantle values 18o 5 5 or having values being slightly depleted down to 3 0 5 5 ultramafic rocks are either fresh or serpentinized they have 18o mainly around mantle values and d s are between 250 and 100 for the mafic part of the ophiolite the isotopic compositions correspond to hydrothermal interaction with seawater derived fluids under zeolite to greenschist facies but the trondjhemites were additionally affected by fluids poorer in d in particular the gabbros reacted with seawater derived fluids under amphibolite facies conditions as seen from their secondary mineralogy and their 18o depleted pyroxenes and subsequently were pervasively reacted under greenschist zeolite facies conditions during which the high 18o albitized plagioclase formed this occurrence of amphibolite facies conditions followed by greenschist zeolite facies conditions can be interpreted either to be a result of slow cooling of the oceanic crust at the ridge or to result from a fundamentally lower temperature hydrothermal interaction if compared with other ophiolites in contrast the d s of the serpentine 100 from the ultramafics are attributed to fluids of meteoric origin at high elevation nevertheless the particular location of the serpentinized harzburgites just beneath the gabbros and the high d dolerite sills and dikes 60 d 40 enclosed in these serpentinized harzburgites suggests an oceanic origin and therefore the possibility of hydrogen isotope exchange between serpentine and meteoric fluids after the obduction the xigaze ophiolite sequence displays very little 18o depleted rocks relative to mantle oxygen composition they cannot balance the amount of 18o enriched rocks consequently the result of the hydrothermal interaction between the xigaze ophiolite sequence and the seawater is an 18o depletion of the seawater however the contribution of xigaze type ridges to the buffering of 18o in cretaceous seawater was probably small

constraints on the origin of archean trondhjemites based on phase relationships of nuk gneiss with h2o at 15 kbar we report the t x h2o phase relations for the trondhjemitic nuk gneiss which comprises the principal component of the second phase of archean 3 0 2 8 by igneous activity in the godthab region of southwestern greenland a pressure of 15 kbar was chosen to place constraints on possible protoliths for trondhjemitic melts at lower crustal depths under h2o saturated conditions a melting interval of 135 c separates the solidus at 610 c from the liquidus at 745 c h2o saturation at 15 kbar occurs at approximately 15 5 wt h2o the h2o undersaturated liquidus extends along a curved path from 745 c at 15 5 wt h2o to 1100 c at 2 h2o lower h2o contents were not investigated at low h2o contents 7 mafic residues consisting of some combination of hb ga ep and bi are possible and could correspond to amphibolitic source rocks at lower melt h2o contents 5 possible residues consist of na pl qz ga and could correspond to an earlier generation of tonalitic trondhjemitic rocks however such residues would not impart the highly fractionated ree patterns characteristic of archean trondhjemites if a first generation of tonalitic trondhjemitic melts was generated by higher pressure partial fusion of eclogite and emplaced at 55 km depth it would crystallize to an assemblage consisting almost entirely of na pl qz with highly fractionated ree patterns these rocks in turn could be partially melted to yield a second generation of trondhjemites which would inherit the highly fractionated ree patterns because neigher pl nor qz is capable of significantly fractionating hree from lree

precambrian u pb zircon ages in eclogites and garnet pyroxenites from south brittany france an old oceanic crust in the west european hercynian belt abstract u pb zircon ages have been determined for two eclogites from the vendee and for two garnet pyroxenites from the baie d audierne in an episodic pb loss model the two discordia would give upper intercept ages around 1300 1250 ma and lower intercepts ages of 436 384 ma two interpretations are proposed 1 the 1250 1300 ma ages may reflect an unspecified upper mantle event or process the paleozoic ages correspond to the tectonic emplacement of an eclogitic mantle fragment into the continental crust 2 the protolith may have been extracted from the upper mantle 1250 1300 ma ago and stored in a crustal environment until it was metamorphosed under high pressure conditions around 400 ma ago this latter model is favoured by available geologic and isotopic data consequently we propose that a 1300 ma old oceanic crust was tectonicly incorporated into a sialic basement during the proterozoic this mixture was subsequently subducted during the paleozoic

refining the alkenone pco2 method i lessons from the quaternary glacial cycles abstract the alkenone pco2 method is one of the most widely used approaches to reconstruct atmospheric co2 in the cenozoic the method depends upon fractionation of stable carbon isotopes during algal photosynthesis expressed as ep37 2 and a physiological scaling parameter b that accounts for biological factors such as growth rate cell size and membrane permeability alkenone derived co2 records for the late pleistocene however are poorly correlated with ice core co2 challenging the classic model that considers most of the co2 used for coccolithophore photosynthesis to be acquired through simple diffusion in this study we investigate the nature of the b term and the underlying patterns of the sensitivity of ep37 2 to pco2 changes we generated two new ep37 2 records from the south china sea md01 2392 and tropical atlantic ocean odp 668b and compiled other published ep37 2 records over glacial interglacial cycles using the ep37 2 data ocean temperature estimates and ice core co2 we were able to back calculate the corresponding values of b at all locations b varies over glacial cycles the highest values of b correspond to peak interglacial stages indicating that the phytoplankton growth rate is faster or cell size is smaller during interglacials than during glacial periods we further show that the range of ep37 2 between glacial and interglacial conditions ep37 2 scales with growth conditions consistent with the predictions of the carbon isotope fractionation model based on co2 diffusion in other words the sensitivity of ep37 2 to pco2 changes increases where the modern b values are large contradicting the recommendations that oligotrophic sites are the best for alkenone co2 applications because of the presumed stability of b using the average back calculated b value for each site the composite pco2 estimates from md01 2392 and odp 668b the two sites with adequate ep37 2 sensitivity show broad agreement with the ice core co2 record

seasonal thermal fronts on the northern south china sea shelf satellite measurements and three repeated field surveys seasonal thermal fronts associated with wind driven coastal downwelling upwelling in the northern south china sea are investigated using satellite measurements and three repeated fine resolution mapping surveys in winter spring and summer the results show that vigorous thermal fronts develop over the broad shelf with variable widths and intensities in different seasons which tend to be approximately aligned with the 20 100 m isobaths driven by the prevailing winter summer monsoon the band shaped fronts were observed with a magnitude exceeding 0 1 degrees c km in the subsurface and accompanied by energetic coastal downwelling upwelling due to shoreward offshore ekman transport the downward upward tilting of seasonal thermoclines across the shelf exceeds 20 m significantly contributing to the development of thermal fronts over the shelf in addition the diagnostic analysis of potential vorticity pv suggests that the summer frontal activities induced by the coastal upwelling are more stable to convection and symmetric instabilities in comparison to the winter fronts associated with downwelling favorable monsoon forcing this is primarily due to their essential differences in the upper ocean stratification and horizontal buoyancy gradients arising from wind forcing at the same time the coastal currents are substantially regulated by the seasonal winds an expected lag correlation between the velocity from mooring measurements and alongshore wind stress is detected near the frontal region these results indicate that seasonal wind forcing plays an important role in the frontal activities and coastal water transport over the shelf

petrology and geochemistry of xenoliths from the northern baltic shield evidence for partial melting and metasomatism in the lower crust beneath an archaean terrane lower crustal xenoliths entrained in a paleozoic ultramafic lamprophyre breccia pipe on elovy island kola peninsula russia represent some of the oldest lower crustal material yet investigated from europe the xenoliths vary from feldspar poor garnetrich rocks which resemble eclogites to feldspar rich garnet granulites quartz rich felsic granulites as well as pyroxenites and amphibole rich rocks are also present the mafic granulites eclogites represent a suite of gabbros and norites that is related by olivine fractionation the igneous protoliths may have formed in a manner analogous to lower crustal rocks from most other european xenolith localities i e by basaltic underplating but magmatic cumulates are not in evidence the kola lower crust was subjected to one or more metasomatic events which introduced up to 45 phlogopite and or amphibole into both eclogites granulites and pyroxenites the resulting rocks have strong enrichments in rb ba and k indicating that the lower crust is not uniformly depleted in lil and heat producing elements siliceous 65 sio2 and mafic 50 sio2 lithologies coexist in migmatitic xenoliths which provide evidence for partial melting processes and restite formation in mafic metaigneous lower crust the relationship if any between partial melting and metasomatism is unclear

satellite observation of upwelling along the western coast of the south china sea abstract we observed the evolution of upwelling along the western coast of the south china sea scs the data we used are noaa national oceanic and atmospheric administration satellite avhrr advanced very high resolution radiometer ir infrared images taken in 1996 and 1997 summer at the hrpt high resolution picture transmission receiving station built on tai ping island which is located in the central scs an upwelling intensity defined by the total heat loss in the upwelling cold water region is used to determine the relationship between coastal upwelling and the wind stress derived from the ers 2 european remote sensing satellite data the results show that the upwelling intensity has a good linear relationship with the total alongshore wind stress while it has a low correlation with the cross shore component of wind stress these results imply that the alongshore wind stress is the main factor to pump the cold water up to the sea surface layer meanwhile the satellite infrared images also indicate that the centroid of cold water moved southward from 15 n to 11 n during the observation period the size of upwelling area changed as well and finally evolved into a cold jet stretching offshore along 11 n 12 n in the mid august 1997 satellite infrared and altimeteric data show that the evolution of upwelling region is closely associated with the development of two anticyclonic circulations in the western scs

liδ18osio2 systematics in volcanic rocks and mafic lower crustal granulite xenoliths abstract li 18 o sio 2 relationships have been examined for suites of spilitized basaltic rocks dsdp 504b xigaze ophiolite blanco fracture zone greater caucasus rhenohercynian fold belt and intra plate evolved tholeiites northern hessian depression and vogelsberg w germany mount falla transantarctic mountains relative to unaltered morb and intra plate primary olivine tholeiites both the spilitic rocks and the evolved tholeiites are characterized by li and 18 o enrichment for the spilitic rocks li and 18 o enrichment is accompanied by a loss of sio 2 as a result of seawater hydrothermal alteration whereas the evolved tholeiites have gained sio 2 li and 18 o from fractionation of mafic phases and assimilation of crustal rocks on li vs sio 2 and 18 o vs sio 2 diagrams the two rock groups plot largely in distinct fields suggesting the possibility of so distinguishing between such lithologies in the ancient rock record mafic granulite xenoliths from the northern hessian depression have elevated li and 18 o abundances at low sio 2 contents even after correction for extraction of felsic components their li 18 o sio 2 signatures plot within the field of spilitic protoliths suggesting that the lower crust in this region contains relics of spilitic rocks from a former oceanic crust

indian ocean capacitor effect on indo western pacific climate during the summer following el nino significant climate anomalies persist through the summer june august after el nino dissipates in spring over the equatorial pacific they include the tropical indian ocean tio sea surface temperature sst warming increased tropical tropospheric temperature an anomalous anticyclone over the subtropical northwest pacific and increased mei yu baiu rainfall over east asia the cause of these lingering el nino effects during summer is investigated using observations and an atmospheric general circulation model gcm the results herein indicate that the tio warming acts like a capacitor anchoring atmospheric anomalies over the indo western pacific oceans it causes tropospheric temperature to increase by a moist adiabatic adjustment in deep convection emanating a baroclinic kelvin wave into the pacific in the northwest pacific this equatorial kelvin wave induces northeasterly surface wind anomalies and the resultant divergence in the subtropics triggers suppressed convection and the anomalous anticyclone the gcm results support this kelvin wave induced ekman divergence mechanism in response to a prescribed sst increase over the tio the model simulates the kelvin wave with low pressure on the equator as well as suppressed convection and the anomalous anticyclone over the subtropical northwest pacific an additional experiment further indicates that the north indian ocean warming is most important for the kelvin wave and northwest pacific anticyclone a result corroborated by observations these results have important implications for the predictability of indo western pacific summer climate the spatial distribution and magnitude of the tio warming rather than simply whether there is an el nino in the preceding winter affect summer climate anomalies over the indo western pacific and east asia

origin of the tertiary basaltic volcanism in the northern hessian depression volcanic activity started about 20 ma before present with quartz tholeiites qth had a climax with alkali olivine basalts aob 13 to 14 ma ago and ended 7 ma ago with nepheline basanites nb and olivine nephelinites on aob covers 73 of the volcanic area about 250 basalts and peridotite xenoliths were sampled for investigation an upper mantle layer ranging from about 90 to 60 km depth has been conditioned for a preferential alkali basalt production by advection of h2o co2 fluids containing si al ca k na p as major constituents beside numerous incompatible minor elements at the onset of the geodynamically triggered mantle conditioning locally restricted diapirism into shallow depth has caused formation of olivine tholeiite magmas oth at about 1 300 c by partial melting all of these oth primary melts intruded due to a favourable compressibility into granulites of the lower crust the rare qth basalts are their derivative magmas which have been slightly contaminated in the crust magmas of the subsequent alkali basaltic volcanism aob baob nb on mon formed by in situ partial melting at about 75 to 90 km depth after depression of the peridotite solidi by fluids to temperatures 1 200 c except many aob these magmas are primary melts as characterized by olivine melt distribution coefficients of mg fe2 kd 0 29 to 0 34 by ni concentrations 260 to 330 ppm and the occurrence of peridotite xenoliths rapid rise of gas charged melts due to saturation in co2 prevented separation of olivine etc and of xenoliths the sequence of magmas from oth to on or mon is formed from decreasing proportions of orthopyroxene opx and increasing contributions of clinopyroxene cpx and phlogopite ph at almost equal proportions of spinel sp incongruent melting of opx and cpx for oth aob nb and on is correlated with precipitation of olivine the average xenolith composition 73 ol 18 opx 7 cpx 1 1 sp and 1 3 0 5 ph was used to model the sources of the investigated melts by 9 incompatible elements and to calculate degrees of partial melting the occurrence of garnet cannot be reliably excluded by modelling on the basis of hree distribution coefficients the average xenolith composition was used for modelling because of its resemblance with worldwide sampled depleted mantle inclusions for avoiding to exhaust at least one mineral of the model mantle in the support of the norm composition of oth aob nb and mon magmas the degrees of partial melting cannot exceed 12 5 6 6 and 4 respectively mantle containing about 500 ppm k and the correlated incompatible elements like the average of 36 xenoliths allows to explain the formation of oth magmas aob nb and on melts require peridotite with slightly less than 1 500 ppm k 670 ppm p and proportions of the correlated elements lree sr ba zr rb cs ta th hf u which are higher than their abundance in primitive mantle rocks about 20 of the xenoliths have this composition metasomatism of fluids with these elements must have been an immediate precursor of the alkali basaltic volcanism otherwise the preservation of a local disequilibrium in 87sr 86sr ratios between cpx cores and total rock at upper mantle temperatures cannot be explained

abnormal upwelling and chlorophyll a concentration off south vietnam in summer 2007 the present study investigates a strong upwelling and concurrent phytoplankton bloom off the south vietnam coast in august 2007 analysis of the alongshore wind offshore ekman transport wind stress curl and other parameters indicates the southwesterly summer monsoon plays an important role in this peculiar case the change of monsoonal wind involves variations of atmospheric circulation on multiple time scales on the interannual time scale a positive indian ocean dipole iod in 2007 accompanying with a la nina event acts to enhance the southwesterly monsoon over the south china sea scs the enhanced southwesterly wind is regarded as a major factor in promoting the upwelling and the phytoplankton bloom off the south vietnam coast on the intraseasonal time scale variations of the sea surface temperature sst and sea surface wind at 30 60 day periods reveal that the sst cooling develops with the evolution of the southwesterly wind anomalies with nearly one week delay implying the great significance of the madden julian oscillation mjo moreover a tropical storm formed in the western scs in early august reinforces the westerly wind and sst cooling among multiple factors on different time scales the mjo event is considered as the major cause since it induces the maximum velocity 4 m s of the southwesterly wind anomalies as a result the high chlorophyll a concentration 0 56 mg m 3 and low sst center 27 degrees c develops in the region off the south vietnam coast and advects to the central scs riding on the northern rim of the southern anticyclonic gyre

origin of granulite terranes and the formation of the lowermost continental crust differences in composition and pressures of equilibration between exposed regional granulite terranes and suites of granulite xenoliths of crustal origin indicate that granulite terranes do not represent exhumed lowermost crust as had been thought but rather middle and lower middle crustal levels application of well calibrated barometers indicate that exposed granulites record equilibration pressures of 0 6 to 0 8 gigapascal 20 to 30 kilometers depth of burial whereas granulite xenoliths which also tend to be more mafic record pressures of at least 1 0 to 1 5 gigapascals 35 to 50 kilometers depth of burial thickening of the crust by the crystallization of mafic magmas at the crust mantle boundary may account for both the formation of regional granulite terranes at shallower depths and the formation of deep seated mafic crust represented by many xenolith suites

regional model simulations of marine boundary layer clouds over the southeast pacific off south america part ii sensitivity experiments abstract the sensitivity of a regional climate model to physical parameterizations and model resolution is investigated in terms of its simulation of boundary layer stratocumulus scu clouds over the southeast pacific specifically the physical schemes being tested include shallow cumulus convection subgrid vertical mixing cloud droplet number concentration cdnc and drizzle as described in part i the model with standard settings captures the major features of the boundary layer in the region including a well mixed marine boundary layer a capping temperature inversion scu clouds and the boundary layer regime transition from the well mixed layer near the coast of south america to a decoupled cloud layer over warmer water to the west turning off the shallow cumulus parameterization results in a dramatic increase in the simulated scu clouds while the boundary layer structure becomes unrealistic losing the decoupled regime over warm water with reduced penetrative mixing at the top of shallow cu

far reaching effects of the hawaiian islands on the pacific ocean atmosphere system using satellite data we detected a wind wake trailing westward behind the hawaiian islands for 3000 kilometers a length many times greater than observed anywhere else on earth this wind wake drives an eastward ocean current that draws warm water from the asian coast 8000 kilometers away leaving marked changes in surface and subsurface ocean temperature standing in the path of the steady trade winds hawaii triggers an air sea interaction that provides the feedback to sustain the influence of these small islands over a long stretch of the pacific ocean

evolution of the petrological and seismic moho implications for the continental crust mantle boundary the chemical and petrological composition of mafic rocks from the lower continental crust are discussed by comparing mafic granulites and meta gabbroic rocks from the ivrea zone and the northern hessian depression nhd xenolith suite both regions contain contrasting types of meta mafic lithologies i former basaltic rocks with trace element patterns ranging from morb iike to subduction related or intra plate tholeutes and u ca and al enriched plagiodase dominated gabbroic rocks showing positive eu anomalies generated by complex deep crustal magmatic processes such as fractionation accumulation of plagiodase and pyroxene and crustal contamination the absence of typical garnet omphadte parageneses in these rocks indicates that the eclogite stability field was not reached during palaeozoic orogenic processes a compilation of experimentally determined p wave velocities and densities for mafic granulites gabbroic rocks eclogites and peridotites is used to evaluate key physical properties of lower crustal mafic rocks during crystal thickening caused by continent continent collision in a step by step scenario it is demonstrated that the position of the seismic moho defined as a first order velocity discontinuity and the petrological moho defined as the boundary between non peridotitic crustal rocks and olivine dominated rocks is not identical for the case that mafic rocks are transformed into edogites at the base of orogenically thickened crust p wave velocities of eclogites largely overlap with those of peridotites although their densities are significantly higher than common upper mantle rocks as a consequence refraction seismic field studies may not detect edogites as crustal rocks this means that the seismic moho detected by refraction seismic field studies appears at the upper boundary between edogites and overlying crustal units since edogites generally have higher densities than peridotites they might be recycled into the deeper lithosphere thereby transferring excess eu into the upper mantle this process could be a due for understanding the negative euanomaly in the upper continental crust which is apparently not balanced quantitatively by the abundance of common mafic crustal rocks

coupled ocean atmospheric waves on the equatorial front striking 20 30 day sea surface temperature waves observed along the equatorial front in the later half of the year are generally believed to be of an oceanic origin here we report the detection of atmospheric waves that are unambiguously tied to these oceanic waves using new satellite measurements of surface winds a general circulation model simulation reveals that these atmospheric waves have a shallow vertical structure trapped in the planetary boundary layer pbl unlike el nino southern oscillation where changes in deep convection are the cause of anomalous winds vertical wave motion penetrates well above the pbl and is likely to impact the distribution and transport of climatically important gas species such as ozone and dimethyl sulfide

crustal temperatures along the central segment of the european geotraverse abstract by including the data on crustal structure the temperature distribution was calculated for a sizeable part of the central segment of the european geotraverse a two dimensional steady state equation of heat conduction in an inhomogeneous medium was solved by means of the finite difference method and several slightly different approaches are compared and discussed the data compiled on the surface heat flow together with the data from the vertical distribution of thermal conductivity and from the heat production along the egt served to test the computation techniques and assess the resultant temperature field it is shown that quite flat isotherms could be expected along the central segment with values of 800 900 c which are typical at 40 km deep

local and remote atmospheric response to tropical instability waves a global view from space a la nina took place in the equatorial pacific in 1999 and strong tropical instability waves tiws developed causing large meanders of a sea surface temperature sst front between the equator and 3 n high resolution satellite measurements are used to describe the variability of sst surface wind velocity column integrated water vapor cloud liquid water and precipitation associated with these strong tiws in 1999 coherent ocean atmosphere patterns emerge in both the pacific and atlantic revealing rich regional characteristics in the far eastern pacific southeasterly trades strengthen weaken over positive negative sst anomalies apparently due to enhanced reduced mixing with high speed winds aloft in the central pacific we find evidence that sst induced sea level pressure changes also contribute substantially to wind fluctuations similar sst wind covariability also exists in the southern hemisphere along 2 s but the wind variability induced by unit sst anomaly is much larger than that north of the equator in the central pacific where the equatorial front is broad the northern sst pattern has a large meridional scale and reaches as far north as 6 n further to the north in the intertropical convergence zone itcz where local sst anomalies are small significant variability is found in clouds and precipitation which is further correlated with surface wind convergence in the atlantic tiw signals in sst are strongly trapped near the equator but they induce significant remote response in the itcz which takes a more southern position than its pacific counterpart and thus more susceptible to tiw influence

arrested kinetic li isotope fractionation at the margin of the ilimaussaq complex south greenland evidence for open system processes during final cooling of peralkaline igneous rocks li contents li and isotopic composition 7 li of mafic minerals mainly amphibole and clinopyroxene from the alkaline to peralkaline ilimaussaq plutonic complex south greenland track the behavior of li and its isotopes during magmatic differentiation and final cooling of an alkaline igneous system li in amphibole increase from b10 ppm in caamphiboles of the least differentiated unit to n3000 ppm in na amphiboles of the highly evolved units in contrast li in clinopyroxene are comparatively low b85 ppm and do not vary systematically with differentiation the distribution of li between amphibole and pyroxene is controlled by the major element composition of the minerals ca rich and na rich respectively and changes in oxygen fugacity due to li incorporation via coupled substitution with ferric iron during magmatic differentiation 7 li values of all minerals span a wide range from 17 to 8 with the different intrusive units of the complex having distinct li isotopic systematics amphiboles which dominate the li budget of whole rocks from the inner part of the complex have constant 7 li of 1 8 2 2 2 n 15 this value reflects a homogeneous melt reservoir and is consistent with their mantle derivation in agreement with published o and nd isotopic data clinopyroxenes of these samples are consistently lighter with 7 liamph cpx as large as 8 and are thus not in li isotope equilibrium these low values probably reflect late stage diffusion of li into clinopyroxene during final cooling of the rocks thus enriching the clinopyroxene in 6 li at the margin of the complex 7 li in the syenites increases systematically from 2 to high values of 14 this coupled with the observed li isotope systematics of the granitic country rocks reflects post magmatic open system processes occurring during final cooling of the intrusion although the shape and magnitude of the li isotope and elemental profiles through syenite and country rock are suggestive of diffusion driven isotope fractionation they cannot be modeled by one dimensional diffusive transport and point to circulation of a fluid having a high 7 li value possibly seawater along the chilled contact in all this study

elastic wave velocities in rocks from a lower crustal section in southern calabria italy compressional and shear wave velocities vp and vs have been measured on 14 rock samples recovered from a high grade metamorphic terrane in the southern part of the calabrian massif which is considered to represent a continuous section of a former deep continental crust the experiments have been carried out in a cubic anvil apparatus at constant confining pressures up to 600 mpa and temperatures ranging from 20 to 700 c using the ultrasonic transmission technique at 600 mpa the compressional and shear wave velocities range from 6 33 km s 1 to 7 74 km s 1 and from 3 54 km s 1 to 4 30 km s 1 respectively variations in velocity are strongly related to variations in mineralogy both vp and vs increase with increasing amphibole pyroxene garnet and sillimanite content the range of velocities measured in the granulite facies rocks under conditions of lower crustal depth is similar to the range of seismic velocities for the crust beneath calabria importantly the metapelite rocks with intermediate silica and high alumina contents have in situ compressional and shear wave velocities which are equivalent to the mafic rocks or even significantly higher the detected high velocity layer at a depth between 15 and 20 km can be explained by a sequence of garnet cordierite sillimanite gneisses for which actual velocities between 6 6 and 7 6 km s 1 have been determined experimentally

upper layer circulation in the south china sea abstract upper layer circulation is investigated by using all available historical temperature profiles combined with climatological temperature salinity relationships in the south china sea two cyclonic eddies are revealed one is located east of vietnam called the east vietnam eddy and the other is off northwest luzon called the west luzon eddy both local ekman pumping and remotely forced basin scale circulation are important mechanisms controlling these two eddies the luzon strait transport relative to 400 db is estimated to be of the order 3 0 sv 1 sv 1 106 m3 s 1 in the mean and has a seasonal cycle dominated by the annual signal with a maximum 5 3 sv in january february and a minimum 0 2 sv in june july pressure gradients are also examined to explore the dynamics of the intrusion of waters from the pacific into the south china sea through the luzon strait

phase relationships of gabbro tonalite granite water at 15 kbar with applications to differentiation and anatexis phase relationships have been determined at 15 kbar with variable h 2o contents for three rocks a gabbro a tonalite and a muscovite granite representing the compositional trend of the calc alkaline rock series experiments were conducted in 0 5 in piston cylinder apparatus using ag pd or pt capsules the results obtained are acceptable representations of the phase relationships for elucidation of petrological processes selected runs with 5 h 2o were completed using au capsules to overcome the problem of iron loss up to the temperature limit of au for reliable electron microprobe analyses of glass garnet clinopyroxene amphibole and plagioclase no glasses could be analyzed in the gabbro the data provide k d values as a function of temperature for pairs of coexisting minerals and liquid the chemical variations are used to evaluate 1 the fractionation trends in hydrous magmas at 55 km in thickened continental crust or uppermost mantle and 2 the products of anatexis of the thickened crust at this depth fractionation of hydrous basalt or anatexis of gabbro and tonalite or their metamorphosed equivalents appears to produce liquids diverging from the calc alkaline trend anatexis of granite produces a liquid less siliceous than itself with some chemical characteristics of syenite

lead in the western south china sea evidence of atmospheric deposition and upwelling in recent decades rapid industrial developments have increased lead pb inputs to the south china sea to quantify the increasing variability we investigated 170 years of skeletal pb and pb isotopes from an offshore central vietnamese coral the pb ca in the coral was 10 16 nmol mol before the mid 1950s and increased to more than 30 nmol mol by 2000 while the regional phaseout of leaded petrol commenced in 2000 coral pb ca continued increasing until 2004 possibly due to regional upwelling and the transport of previously emitted pb from tropical pacific waters the 206pb 207pb ratio in the coral was 1 191 1 195 before mid 1950s suggesting natural sources since then the ratio decreased reaching 1 165 in 2004 lead isotopes show high linearity between natural and chinese emitted pb with the latter contributing 40 60 of the skeletal pb after 2000

continental crust formation seen through the sr and nd isotope systematics of s type granites in the hercynian belt of western france the isotopic compositions of sr nd and pb in leucogranites which are intercorrelated bernard griffiths et al 1985 1 may be explained by the mixing of ancient basement 1800 ma with juvenile crust late precambrian or early palaeozoic this hypothesis does not involve the existence of mid proterozoic crust as apparently indicated by thetdm model ages of the leucogranites ranging between 1600 and 1100 ma the nd isotopes reveal the crustal reworking while sr isotopes mainly record juvenile crust formation this paradox is explained by the geochemical heterogeneity of the sources involved

geochemistry nd and sr isotopes and u pb zircon ages of granitoid and metasedimentary xenoliths from the navajo volcanic field four corners area southwestern united states abstract proterozoic granitoid xenoliths from the navajo volcanic field nvf in the southwestern united states range in composition from tonalite diorite to granite with the latter greatly dominating there is no apparent relationship between chemical or isotopic composition and age geographic location or degree of alteration or deformation of the xenoliths two of the major ages of proterozoic plutonism recognized in the southwest 1 75 1 70 yavapai and 1 45 1 41 ga anorogenic are represented by the nvf xenoliths in some instances within a single diatreme we did not find any xenoliths in the 1 65 1 62 ma mazatzal range the xenoliths are dominantly i types and both nd and sr isotopes and trace element distributions indicate juvenile arc sources approximately 1 8 ga the granite magmas may have been produced by either vapor absent partial melting or fractional crystallization of a tonalite parent juvenile sources must have been available for melting in each of the three periods of magma production and hence some juvenile 1 8 ga crust in this region must have escaped melting in the first two episodes of magmatism and deformation metasedimentary xenoliths are chiefly biotite sillimanite schists garnet biotite schists and garnet paragneisses these three groups are strikingly similar in chemical and isotopic composition suggesting similar graywacke pelite protoliths the schists appear to be limited to the far northern part of the volcanic field consistent with a possible crustal boundary in the basement compositional and thermobarometric results suggest that the biotite schist xenoliths are not restites but that the paragneisses may be mixtures of melt and restite sedimentary protoliths may have been deposited in a forearc basin and later tectonically transported to the deep crust during one or more arc continent collisions in the late paleoproterozoic

seasonal structures of upper layer circulation in the southern south china sea from in situ observations 1 conductivity temperature depth and acoustic doppler current profiler data from six cruises spanning 1989 to 1999 are used to investigate the seasonal structure of the upper layer circulation in the southern south china sea scs the surveys were made during winter late spring summer and late fall more detailed structures not presented in previous studies are found in summer the upper layer circulation of the southern scs is dominated by an anticyclonic gyre with a strong eastward flow on its northern border which originates off the southeast coast of vietnam the summer southeast vietnam offshore current in winter a stronger cyclonic gyre exists in the western portion of the southern scs and a weaker anticyclonic circulation in the eastern portion at the juncture of these two gyres there is a strong northward upwind flow called the winter natuna off shelf current in late spring the anticyclonic gyre begins to form in the northwest and a trace of the natuna off shelf current can still be observed especially subsurface in the southern part of the study area mesoscale eddies are active in this period in late fall the winter type pattern begins to appear the natuna off shelf current and the cyclonic gyre in the northwest part of the southern scs emerge and the summer anticyclonic gyre vanishes in the southeast the currents are basically toward the northeast with an anticyclonic trend revealing a multi eddy feature these upper ocean currents appear consistent with the wind forcing

dynamically active areas in the south china sea detected from topex poseidon satellite altimeter data abstract topex poseidon t p altimeter measurements from december 1992 to april 1998 were processed to study the sea surface height ssh variation in the south china sea scs patterns of variance of the ssh deviations from the four year 1993 1996 mean show that there are three high variation areas in the deep basin the first is at the northern basin west of luzon island 16 18 n 117 119 e the second is at the center of the scs 14 16 n 113 5 114 5 e and the third is off the central vietnam coast 12 13 n 110 112 e from empirical orthogonal function eof analysis we found that the variations of these three active areas are dominated by annual cycles but out of phase the first two areas have the highest ssh in june and the lowest ssh in december the third one off the vietnam coast has the highest ssh in february and the lowest ssh in august the eof analysis also reveals that the variation of ssh in the scs has a response to el nino events

current separation and upwelling over the southeast shelf of vietnam in the south china sea 1 the high resolution unstructured grid finite volume community ocean model fvcom was used to examine the physical mechanisms that cause current separation and upwelling over the southeast shelf of vietnam in the south china sea scs process oriented experiments suggest that the southwesterly monsoon wind is a key physical mechanism for upwelling in that area but not a prerequisite to cause current separation with no wind forcing current separation in summer can occur as a result of the encounter of a southward along shelf coastal current from the north and northeastward buoyancy driven and stratified tidal rectified currents from the southwest the southward current can be traced upstream to the hong river in the gulf of tonkin this current is dominated by semigeostrophic dynamics and is mostly confined to the narrow shelf along the northern vietnamese coast the northeastward currents are generated by tidal rectification and are intensified by the mekong river discharge and southwesterly monsoon wind forcing the dynamics controlling this current are fully nonlinear with significant contributions from advection and vertical turbulent mixing upwelling in the current separation zone can be produced by a spatially uniform constant wind field and can be explained using simple wind induced ekman transport theory this finding differs from previous theory in which the regional dipole wind stress curl is claimed as a key mechanism for current separation and upwelling in this coastal region our scs fvcom driven by the wind stress river discharge and tides is capable of reproducing the location and tongue like offshore distribution of temperature as those seen in satellite derived sea surface temperature imagery

interannual variability of the surface summertime eastward jet in the south china sea the summertime eastward jet sej located around 12 n 110 e 113 e as the offshore extension of the vietnam coastal current is an important feature of the south china sea scs surface circulation in boreal summer analysis of satellite derived sea level and sea surface wind data during 1992 2012 reveals pronounced interannual variations in its surface strength ssej and latitudinal position ysej in most of these years the jas july august and september mean ssej fluctuates between 0 17 and 0 55 m s 1 while ysej shifts between 10 7 n and 14 3 n these variations of the sej are predominantly contributed from the geostrophic current component that is linked to a meridional dipole pattern of sea level variations this sea level dipole pattern is primarily induced by local wind changes within the scs associated with the el nino southern oscillation enso enhanced weakened southwest monsoon at the developing decaying stage of an el nino event causes a stronger weaker sej located south north of its mean position remote wind forcing from the tropical pacific can also affect the sea level in the scs via energy transmission through the philippine archipelago but its effect on the sej is small the impact of the oceanic internal variability such as eddy current interaction is assessed using an ocean general circulation model ogcm such impact can lead to considerable year to year changes of sea level and the sej equivalent to 20 of the observed variation this implies the complexity and prediction difficulty of the upper ocean circulation in this region

upwelling in the continental shelf of northern south china sea associated with 1997 1998 el nino 1 a strong upwelling off the continental shelf of the northern south china sea scs in 1998 summer is reinvestigated using a suite of new satellite measurements and numerical modeling previous studies indicate that the upwelling in the western scs especially off the vietnam coast almost disappears during 1998 summer following the el nino because of the weakened southwest monsoon this study identifies that the coastal upwelling in the adjacent northern scs nscs is significantly strengthened during 1998 summer and the alongshore wind stress is dramatically enhanced over the region as a result the offshore ekman transport in 1998 summer is the strongest almost twice the average of the other 17 years during 1997 2007 the chl a concentrations in the representative upwelling regions are much higher than any in other years further analysis suggests that two adjacent basin scale upwellings in the scs have different responses and maintaining mechanisms because of the anticyclonic atmospheric circulation anomaly over the scs and northwest pacific the northern flank of the atmospheric circulation anomaly intensifies the monsoonal winds off the nscs coast while the southern flank suppresses the southwesterly winds along the vietnam coast

mean three dimensional circulation in the northeast tropical pacific abstract historical xbt data are used to construct a mean climatology of the three dimensional geostrophic circulation in the northeast tropical pacific southwest of mexico and central america and are diagnosed based on linear dynamics forced with satellite scatterometer winds unlike the familiar central tropical pacific where the zonal scales are very large and the wind forcing nearly a function of latitude alone the north pacific east of about 120 w is strongly influenced by wind jets blowing through gaps in the central american cordillera the curl imposed by these wind jets imprints on the ocean producing a distinctive pattern of thermocline topography and geostrophic currents that are consistent with the sverdrup balance notably the weakening of the north equatorial countercurrent near 110 w is due to the wind forcing given the observed stratification and wind stress curl planetary vorticity conservation also determines the distribution of vertical velocity in the region with about 3 5 sv

fe mg mixing in cordierite constraints from natural data and implications for cordierite garnet geothermometry in granulites from chemicaldata on 108 pairs of naturally occurring garnet and cordierite the interchange energy of fe mg mixing in cordierite wo and the free energy change of the exchange equilibrium feralrsiro t t zmgraiosiro y mgralrsiro yzferalosiro in the temperature range of 700 850 c have been extracted using standard methods of linear regression analysis the input thermochemical parameters for multicomponent camg fe mn garnet solid solutions are based on the updated and revised values after ganguly and saxena 1984 e g wr 2500 cal w w 3000 cal calculated on the basis of one third formula unit on the basis of the derived values at 710 760 800 and 850 c fe mg mixing in cordierite has been approximated to a symmetric regular solution the fe mg substitution shows positive deviation from ideality in cordierite with tzi 1 9 34 4 54kj mol of divalent cation the values derived for the free energy of mixing at xi d xi ds 0 5 are 3 26 kj at 700 c and 4 39 kl at 900 c the ag value in joules for the above equilibrium can be expressed as 15079 8 552 incorporating these parameters the geothermometric expression for the exchange equilibrium is

pacific east asian teleconnection how does enso affect east asian climate observational evidence is presented to show a teleconnection between the central pacific and east asia during the extreme phases of enso cycles this pacific east asian teleconnection is confined to the lower troposphere the key system that bridges the warm cold events in the eastern pacific and the weak strong east asian winter monsoons is an anomalous lower tropospheric anticyclone cyclone located in the western north pacific the western north pacific wind anomalies develop rapidly in late fall of the year when a strong warm or cold event matures the anomalies persist until the following spring or early summer causing anomalously wet dry conditions along the east asian polar front stretching from southern china northeastward to the east of japan kuroshio extension using atmospheric general circulation and intermediate models the authors show that the anomalous philippine sea anticyclone results from a rossby wave response to suppressed convective heating which is induced by both the in situ ocean surface cooling and the subsidence forced remotely by the central pacific warming the development of the anticyclone is nearly concurrent with the enhancement of the local sea surface cooling both the anticyclone and the cooling region propagate slowly eastward the development and persistence of the teleconnection is primarily attributed to a positive thermodynamic feedback between the anticyclone and the sea surface cooling in the presence of mean northeasterly trades the rapid establishment of the philippine sea wind and sst anomalies implies the occurrence of extratropical tropical interactions through cold surge induced exchanges of surface buoyancy flux the central pacific warming plays an essential role in the development of the western pacific cooling and the wind anomalies by setting up a favorable environment for the anticyclone sst interaction and midlatitude tropical interaction in the western north pacific

mooring observations and numerical modeling of thermal structures in the south china sea 1 three sets of autonomous temperature line acquisition systems were deployed in the south china sea gaps aside the data covered nearly 3 years at the northern station and about 2 years farther south fluctuations ranged from episodic to interannual internal tides more diurnal than semidiurnal were active basinwide twelve typhoons passed during measurement periods the most severe one typhoon babs in 1998 caused a temperature drop of over 7 c at 50 m despite strong monsoons only near surface temperature showed clear seasonal variations intraseasonal variations induced by mesoscale eddy stood out much better at subsurface depths propagating eddies aside some eddies were seasonal and nearly stationary from daily archives of an eddy resolving data assimilating ocean model east asian seas nowcast forecast system we identified two paradigms leading to the generation of a persistent spring summer warm eddy in the central western basin in normal years a complete cyclonic gyre was driven by a strong winter northeast monsoon water piled up along the periphery of the south china sea afterward a warm eddy could be generated from west of luzon island and propagated westward while intensifying under a weak northeast monsoon such as in el nino years piled up water tended to stay in the southern basin when the wind relaxed in spring warm water returned northward to form a warm eddy in the central western basin transition from sw to ne monsoon also often led to a warm eddy generation in southern latitudes when the summer eastward jet departing from central vietnam broke up

imaging short period variations in lava flux short period e g 1 h variations in lava effusion rate have been detected previously on mount etna sicily but the causes and effects of such changes are poorly understood because of difficulties in obtaining suitably high frequency measurements over long periods here we report short period flux variations in active lava flows recorded in dense time series imagery over a 7 night period using modified remote trail cameras the sequences of night time images show significant pulses of enhanced incandescence interpreted as short period increases in lava flux travelling down channel at velocities of 10 20 m min 1 pulse generation decreased from an average of one pulse per hour on the first night to approximately one per night within a few nights effusion rate changes on these timescales are considered to reflect instabilities in magma ascent and consequently could provide insight into subsurface flow processes

origin of high magnesian andesites in the setouchi volcanic belt southwest japan i petrographical and chemical characteristics high magnesian andesites of middle miocene age occur in southwest japan forming an obvious volcanic belt these andesites have low feo mgo ratios 0 546 0 931 and are rich in ni 101 312 ppm co 30 0 45 1 ppm and cr 208 756 ppm they are relatively aphyric phenocrysts 10 vol and the phenocrysts of magnesian olivine fo88 are in equilibrium with the host high magnesian andesite magmas on the basis of the fe mg exchange partitioning these features suggest that the high magnesian andesites are not differentiated or accumulative they appear to represent primary andesites generated in the upper mantle these southwest japanese high magnesian andesites are rich in incompatible elements and show light rare earth enrichment relative to boninites suggesting that the former is derived from a less depleted mantle source than the latter

circulations and eddies over the south china sea derived from topex poseidon altimetry topex poseidon t p altimeter data were used to derive time varying circulation and eddies over the south china sea scs for 1993 1999 large variabilities of sea surface heights and dense distribution of eddies were found to occur along a band across the scs basin a cross over method is introduced to compute pointwise velocity components the t p derived circula tions and eddies are consistent with the drifter results from the world ocean circulation experi ment data center 1 because of monsoons the scs circulation is largely cyclonic in winter is largely anticyclonic in summer and is modulated interannually by el nifio southern oscillation 2 both cold and warm core eddies were found in the waters east of vietnam west of luzon and west of the luzon strait but their times of occurrence and the way they evolved vary interannually 3 the reversal of the alongshore currents east of vietnam was in complete accordance with wind stress the locations and kinematic properties of eddies over scs were estimated by the least squares method the averaged vorticities of the cold and warm core eddies are 1 684x 10 6 and 1 738x l0 6 tad s respectively and the shearing and stretching deformations are one thousandth of the vorticities the angular velocity of eddy decreases with increasing radius coherence analy sis suggests that the interannual and seasonal variations of circulation are largely due to wind stress and the semi annual variation is largely due to wind stress curl the angular velocities of eddies over the central scs basin are coherent with the magnitudes and signs of wind stress curl the seasonal steric anomaly was also computed and its spatial pattern and scale are quite different from those of circulation and eddy

evolution of the lower continental crust granulite facies xenoliths from the eifel west germany the lower continental crust is a key region to understanding processes of crust mantle differentiation and subsequent evolution of the crust the region is metamorphosed into granulite or amphibolite facies1 2 whereas felsic to mafic granulites with an average intermediate major element composition are typically observed in old exposed lower crustal terranes mafic compositions are preponderant among granulite facies xenoliths transported by young alkalic basaltic volcanics and kimberlites1 radiometrie ages for granulite bulk rocks using the rb sr or u pb methods are usually interpreted as metamorphic ages in contrast sm nd ages obtained on such metamorphics are interpreted to reflect pre metamorphic events3 7 although a case of severe disturbance of the sm nd isotope system during granulite facies metamorphism has also been reported8 we present here sm nd and rb sr isotope data for a suite of mafic lower crustal xenoliths from the hercynian belt our data suggest that the igneous precursors of these granulites differentiated from depleted mantle 1 5 gyr ago in most of these granulites this evidence for a mid proterozoic age has been obliterated by a young 172 myr metasomatic overprint by mantle derived fluids or melts

origin of spilitic rocks from the southern slope of the greater caucasus a suite of 39 spilitic basalts and andesites of bajocian age was analyzed for the major elements and li rb sr ba sc v cr co ni and seven ree hf ta and th were analyzed in 20 samples sr and o isotope ratios have been determined for selected whole rock samples the occurrence of biotite and actinolite indicates maximum temperatures of hydrothermal reactions slightly above 400 c prehnite pumpellyite and epidote formed at lower temperatures chlorite and sodic plagioclase are abundant products of hydrothermal seawater alteration a comparison between weakly and intensively altered basalts demonstrates that the largest proportion of al v cr co ni and the ree was immobile during spilitization enrichment in 18o is correlated with the gain of h2o co2 na2o and li which exceeds pre spilitic levels initial 87sr86sr ratios for 10 whole rock samples range from 0 7040 to 0 7049 relics of fresh clinopyroxene phenocrysts from the spilitic basalts and andesites have initial 87sr86sr ratios between 0 7037 and 0 7044 and 18o values between 4 5 and 5 6 smow whole rock samples have higher 87sr86srinit ratios and higher 18o values when compared to their clinopyroxene phenocrysts which is explained as a result of alteration by seawater average 18o values of 11 smow along with the enrichment of li suggest that the major alteration occurred at temperatures below 200 c the spilitic basalts have higher average sc v cr co and ni concentrations relative to the spilitic andesites the abundances of these elements in the spilitic andesites are quite similar to those in typical orogenic andesites the correlation of cr and ni in both the spilitic basalts and the spilitic andesites is explained by various degrees of fractionation of olivine and clinopyroxene although ta and th may have been mobilized to minor extents the majority of the analyzed samples has hf ta th relations which are typical of subduction related volcanic rocks assuming an olivine tholeiite as the parental melt from which the basaltic and andesitic magmas were derived the average la and ce concentrations in these rocks require a metasomatically enriched peridotite source with 5 times chondritic la and ce abundances the coexistence of andesites and basalts at the southern slope of the greater caucasus along with the occurrence of ophiolites in the lesser caucasus suggests that both could be related to a middle jurassic subduction zone in this region

crustal xenoliths from tertiary volcanics of the northern hessian depression a suite of crustal xenoliths from tertiary basaltic tuffs of the northern hessian depression nhd volcanic field comprises abundant meta igneous pyroxene granulites of mafic noritic to anorthositic iat and tonalitic composition less abundant are granitic tonalitic and leucogranitic gneisses and metasedimentary xenoliths a total of 49 samples were analyzed for modal compositions for major and trace elements including li rb sr ba cs v sc cr co ni y zr nb ta hf th and ree and oxygen isotopes two pyroxene thermometry yields temperatures between 700 and 900 c for mafic and noritic granulites feldspar thermometry indicates temperatures of 660 710 c for tonalitic granulites and 470 520 c for granitic and tonalitic gneisses one highly depleted sillimanite rich metasediment contains cordierite and garnet which have equilibrated at temperatures of 780 c the general lack of garnet in the mafic and noritic granulites and the presence of sillimanite in felsic xenoliths indicates that metamorphic pressures have not exceeded 10 kb major and trace element data and oxygen isotope compositions of the mafic granulites are compatible with an origin from spilitized enriched type morb rocks enrichment in 18o to 11 and in li to 34 ppm at average sio2 contents of 44 1 wt these low t spilites were transformed into amphibolites and then pyroxene granulites during subsequent high temperature metamorphic events low si al k and rb concentrations along with an contents in plagioclase ranging from near 50 to 98 mole percent suggest that amphibolite facies protoliths have generated tonalitic melts during partial melting at temperatures above 700 c the mafic granulite xenoliths are interpreted as restites whereas the tonalitic samples probably represent the extracted partial melts derived by 20 to 30 percent degree of melting metasedimentary xenoliths strongly depleted in granitic component could represent restites from which granitic s type partial melts have been extracted tonalitic and leucogranitic gneisses including one trondhjemite xenolith have many chemical characteristics e g ree distribution in common with tonalite trondhjemite granodiorite suites of the north atlantic region but cannot be accounted for a more specific origin estimated elastic properties of the main types of nhd xenoliths yield p wave velocities of 6 0 6 4 km 1 for granitic tonalitic and trondhjemite gneisses including tonalitic granulites and 6 5 7 0 for the more mafic xenoliths when compared with two seismic depths vp profiles these data are in accordance with a model where the mafic andesitic noritic and tonalitic granulites comprise abundant rock types at depths between 29 km moho and 20 km which mainly consists of old oceanic crust including subduction related volcanic products the more felsic xenoliths probably represent material from depths between 12 and 20 km

beginning of melting in the granite system qz or ab an h2o the beginning of melting in the system qz or ab an h2 o was experimentally reversed in the pressure range p text h text 2 text o 2 15 kbar using starting materials made up of mixtures of quartz and synthetic feldspars with increasing pressure the melting temperature decreases from 690 c at 2 kbar to 630 c at 17 kbar in the an free alkalifeldspar granite system qz or ab h2o in the granite system qz or ab an h2o the increase of the solidus temperature with increasing an content is only very small in comparison to the alkalifeldspar granite system the solidus temperature increases by 3 c 7 c if albite is replaced by plagioclase an 20 an 40 the difference between the solidus temperatures of the alkalifeldspar granite system and of quartz anorthite sanidine assemblages system qz or an h2o is approximately 50 c

crustal xenoliths from cenozoic volcanic fields of west germany implications for structure and composition of the continental crust crustal xenoliths in three cenozoic volcanic fields of west germany the northern hessian depression nhd the eifel and the urach hegau include medium to high grade meta sedimentary and felsic to mafic meta igneous rocks also present in all three suites are pyroxenites and hornblendites for each volcanic field a model crustal profile is proposed based on calculated or measured p wave velocities of xenoliths and depth vp relationships egt central segment and rhenish massif traverses the xenolith lithologies from the nhd and the eifel show some similarities the middle crust between the depths of about 10 and 25 km consists mainly of meta sediments felsic gneisses and granulites meta sedimentary rock types are particularly abundant in the eifel at depths of between about 5 and 15 km but are less common within the nhd xenolith collection the felsic gneisses range from meta granites to meta tonalites i and s type eifel meta sediments range from meta pelites to meta greywackes and meta quartzites the nhd xenolith suite contains a few highly depleted granulite facies meta sedimentary fragments at depths between 24 and 26 km the increase in vp from about 6 8 to 8 km s 1 28 34 km is correlated with the presence of mafic granulites intercalated with eclogites pyroxenites and hornblendites beneath north hessia the granulite layer problably grades into a composite eclogite peridotite layer at the lower part of this transition zone the crust beneath the urach hegau consists largely of meta sediments with subordinate felsic meta igneous rocks most of the meta sedimentary samples seem to be depleted in felsic components suggesting intra crustal differentiation by partial melting the urach crust contains lithologies which are similar to the outcropping moldanubian type para gneisses of the black forest mafic and ultramafic xenoliths from the urach hegau differ in their mineralogy and chemical composition from the eifel and nhd mafic granulites they represent meta cumulates derived from alkaline magmas which intruded the base of the crust and underwent deformation and recrystallization petrographic and chemical differences between urach hegau and eifel nhd are believed to reflect the contrasting styles of crustal evolution in the rhenohercynian and the moldanubian belts of the variscan orogen

selective response of the south china sea circulation to summer monsoon abstractthe response of the south china sea scs circulation to intraseasonal variability of the summer monsoon is studied with both observations and a 1 5 layer reduced gravity model intraseasonal variability of the scs summer monsoon is characterized by evolution of the wind jet intensity in the midbasin with typical amplitude of 6 m s 1 and several peaks on its power spectrum between 10 and 60 days however this study finds that intraseasonal variability of the sea surface height ssh in the scs presents significant variability to the southeast of vietnam with amplitude of 6 cm and a period only between 40 and 60 days this implicates the frequency selectivity of oceanic response to wind forcing numerical experiments suggest that the intrinsic variability of the scs circulation accounts for this phenomenon based on the rossby basin mode theory this is explained by the interaction between the long westward propagating rossby waves and the short eastward propagating rossby waves

garnet breakdown in some deep seated garnetiferous xenoliths from the central sierra nevada petrologic and tectonic implications abstract garnets in garnetiferous xenoliths from big creek pick and shovel and chinese peak volcanic pipes occurring along the axial region of the sierra nevada batholith have broken down to variable degrees to optically opaque and extremely fine grained kelyphitic rims and seams in some cases only opaque pseudomorphs of garnet remain in others garnet occurs only as a tiny relict within an opaque mass in still others the kelyphite forms a rim and pervades the garnet grain in a complex reticulate fashion backscattered electron imaging and electron microprobe analyses reveal that the unaltered portions of garnets exhibit negligible compositional variations the unaltered portion is often surrounded by a resorbed rim whose composition is slightly different from that of the bulk garnet however no systematic difference occurs between the compositions of resorbed rims and those of the unaltered garnets around the resorbed rim lies a zone composed of symplectic intergrowths of aluminous spinel aluminous orthopyroxene and calcic plagioclase an91 compositions of the symplectite spinels and orthopyroxenes are different from the compositions of those occurring as major discrete phases in the rocks the possibility that the kelyphites results from oxidation is ruled out two alternatives for the origin of these kelyphites seem viable in the first they are the result of isochemical decomposition of garnet due to transport by the host lavas from depth to the surface in the second they are produced by breakdown and retrogression of garnet due to tectonic transport of the precursor rocks from high p t conditions to lower p t conditions before their incorporation into the host volcanics the second alternative is favored and is supported by the following arguments 1 decompression due to transport of the xenoliths by the volcanics should essentially take place along an adiabat and would most likely cause partial melting no melt phase was found in the symplectites 2 such rapid adiabatic decompression would arrest the original high p t condition of equilibration of the primary xenolith mineralogy the p t conditions of equilibration of the primary xenolith mineral assemblages are found to range from the 11 24 kbar and 600 900 c these low p t conditions indeed indicate a re equilibration of the primary mineral assemblages at a shallower depth 3 the garnet breakdown reaction also involved clinopyroxene and produced an overgrowth of fe and al rich and na poor clinopyroxene around the primary clinopyroxene 4 using the known phase compositions a balanced reaction which involves primary phases and the symplectite phases can be written 5 thermodynamic modelling of the garnet breakdown phenomenon according to the reaction camgsi2o6 2mg3al2si3o12 3mg2si2o6 caal2si2o8 mgal2o4 yields the p t condition for garnet breakdown at 841 c 15 kbar for the sample ps 10 for example the original subsolidus re equilibration p t condition of the primary mineral assemblages for this sample is calculated as 892 c 23 kbar this calculation signifies uplift of the subsolidus garnet clinopyroxenite assemblage along a superadiabatic p t path the hypothesis set forth in turn suggests movement of the solid crust mantle segments along a superadiabatic path from a high p t regime to lower p t conditions thus the crust mantle segments underlying the sierra nevada batholith represented by the xenoliths originated at a greater depth and were tectonically uplifted prior to becoming entrained within the volcanic hosts this dynamic model is compatible with the geological scenario of the western united states

fast assimilation of xenoliths in magmas analytical and numerical modeling indicates that melting of xenoliths in magmas may be controlled by viscous flow the xenolith melt will be removed immediately by the host magma if flow is present and new xenolith melt can be produced this melting mechanism is referred to as ablation ablation dominates the melting process in earlier experiments in the system diopside we propose that complex phases solid solutions undergo ablation when the heat flow into a xenolith is high ablation is found to be controlled by a nearly linear rate law after a short heating up period the average computed ablation rates coincide with earlier experiments of diopside we predict steady state ablation rates at 20 k superheating for cristobalite 3 8 10 4 m s high sanidine 1 6 10 4 m s calcite 4 9 10 5 m s clinoenstatite 4 0 10 5 m s and forsterite 3 2 10 5 m s a cold xenolith might cool down the host liquid next to it below the glass transition temperature and to accrete a glassy crust such chilled selvage accretion will modify the total assimilation rates of granulites by less than 10 for xenolith radii 20 cm ablation appears to be more effective as compared to diffusion controlled assimilation this could explain the worldwide predominance of mafic and ultramafic mantle and lower crust compared to felsic lower crustal xenoliths

summer monsoon induced upwelling dominated coastal sea surface temperature variations in the northern south china sea over the last two millennia the south china sea scs situated to the north of the indo pacific warm pool ipwp is under the strong influence of the asian monsoon system however coastal sea surface temperature sst reco

interannual variability of the south china sea in a data assimilation model 1 sea surface height ssh variations in the south china sea are examined using results from a data assimilation model after the ssh data have had the annual cycle removed principal component analysis illustrates two distinct anomaly patterns the first mode strongest off vietnam would affect the basin wide gyre intensity the second mode consists of a meridional dipole feature with a nodal line around 12 n and is related to the development of the eastward jet and upwelling off vietnam both eof modes have significant interannual variations and are highly correlated to the enso events the leading phase of mode 2 coefficient provides preliminary evidence for the air sea interaction and the pacific east asian teleconnection an innovative mechanism is proposed to describe a weakened upwelling off luzon in winter 1998 an extra strong basin wide warming in summer 1998 persists into fall and winter preventing the formation of winter upwelling off luzon in that year

the influence of enso on an oceanic eddy pair in the south china sea an eddy pair off the vietnam coast is one of the most important features of the summertime south china sea circulation its variability is of interest due to its profound impact on regional climate ecosystems biological processes and fisheries this study examines the influence of the el nino southern oscillation enso a basin scale climatic mode on the interannual variability of this regional eddy pair using satellite observational data and historical hydrographic measurements over the last three decades the eddy pair strengthened in 1994 and 2002 and weakened in 2006 2007 and 2008 it was absent in 1988 1995 1998 and 2010 coinciding with strong el nino to la nina transitions composite analyses showed that the strong transition events of enso led to radical changes in the summer monsoon through the forcing of a unique sea surface temperature anomaly structure over the tropical indo pacific basin with weaker zonal wind a more northward wind direction and the disappearance of a pair of positive and negative wind stress curls the eastward current jet turns northward along the vietnam coast and the eddy pair disappears this article is protected by copyright all rights reserved

boninite petrogenesis and alteration history constraints from stable isotope compositions of boninites from cape vogel new caledonia and cyprus 18o values of unaltered olivine and pyroxene phenocrysts in boninites from several areas range from 5 8 to 7 4 and indicate that the source for most boninites is more 18o rich than morbs and other oceanic basalts the source for oxygen and other major elements is most likely a refractory portion of the mantle having a 18o value of up to 7 0 to which must be added a small amount of h2o rich fluid to induce partial melting this fluid which is derived from subducted crust is the vehicle for lrees including nd the variable normally low nd values typical of boninites do not correlate with the 18o values post eruptive exchange of oxygen in the glass of boninites with that of sea water at low temperatures 150 c produces 18o values of 10 in optically fresh glass hydration of the glass has increased the water contents of most boninites from estimated magmatic values of 1 2 wt to 2 4 wt and produced d values of 80 which may be lower than the original magmatic d values in contrast to most submarine pillow basalts the magmatic volatile composition of boninite lavas has been extensively modified as a result of post eruptive interaction with seawater

formation of methane related authigenic carbonates within the bioturbated zone an example from the upwelling area off vietnam abstract in the biologically high productive area off vietnam authigenic carbonates formed in the bioturbated zone while methane was oxidized microbially under anaerobic conditions open crustacean burrows spongeliomorpha connected to the seafloor acted as conduits for methane as suggested by intense cementation of burrow walls having a light c isotope signature although seawater circulated within these open inhabited tubes conditions favorable for anaerobic oxidation of methane aom occurred trypanites cementation started at several spots that coalesced later to form the nodule carbon isotopes indicate a biogenic methane source 13 c carb reaching 49 to 40 v pdb while higher 13 c values imply mixing with carbon from other sources that is very likely within the bioturbated zone the cement is generally fine grained 18 o values of 5 1 reflect the general 18 o enriched isotope signature of the bottom water in south china sea especially during glacial times but influence of water released from decaying gas hydrate cannot be excluded the studied nodule was found on top of a slump that displaced it

summer upwelling in the south china sea and its role in regional climate variations seasonal and interannual variations of summer upwelling off the south vietnam coast and the offshore spread of cold water are investigated using a suite of new satellite measurements in summer as the southwesterly winds impinge on annam cordillera a north south running mountain range on the east coast of indochina a strong wind jet occurs at its southern tip offshore east of saigon resulting in strong wind curls that are important for ocean upwelling off the coast in july and august an anticyclonic ocean eddy develops to the southeast advecting the cold coastal water offshore into the open south china sea scs the center of this cold filament is located consistently north of the wind speed maximum indicating that open ocean upwelling helps to cool the ocean surface corroborating evidence for the cold filament is found in ocean color observations that reveal a collocated tongue of high chlorophyll concentration the development of this cold filament disrupts the summer warming of the scs and causes a pronounced semiannual cycle in sst moreover the cold filament is an important player in interannual variability in the summer scs in 1998 the cold filament and mid summer cooling never took place giving rise to a strong basin wide surface warming interannual sst variance has a local maximum over the climatological cold filament and is much greater than the variance over the adjacent indian and western pacific oceans a cold filament index is constructed which displays significant lagged correlation with sst in the eastern equatorial pacific and indian oceans indicative of a teleconnection from el nino

covariations of sea surface temperature and wind over the kuroshio and its extension evidence for ocean to atmosphere feedback abstract satellite microwave measurements are analyzed revealing robust covariability in sea surface temperature sst and wind speed over the kuroshio extension ke east of japan ocean hydrodynamic instabilities cause the ke to meander and result in large sst variations increased reduced wind speeds are found to be associated with warm cold sst anomalies this positive sst wind correlation in ke is confirmed by in situ buoy measurements and is consistent with a vertical shear adjustment mechanism namely an increase in sst reduces the static stability of the near surface atmosphere intensifying the vertical turbulence mixing and bringing fast moving air from aloft to the sea surface south of japan the kuroshio is known to vary between nearshore and offshore paths these paths are very persistent and can last for months to years as the kuroshio shifts its path coherent wind changes are detected from satellite data in particular winds are high south of tokyo when the kuroshio takes the near

eddy effects on sea surface temperature and sea surface wind in the continental slope region of the northern south china sea 1 warm and cold sea surface temperature sst tongues on weather timescales are detected in the continental slope region of the northern south china sea nscs and their effects on sea surface wind are studied using satellite observations crossing the basin scale sst front geostrophic currents between cyclonic and anticyclonic eddies induce the warm and cold sst tongues during the northeast monsoon corresponding to the warm and cold sst tongues the sea surface wind is highly uneven in spatial distribution its speed is faster slower over the warm cold sst tongues than the surrounding areas the sst and sea surface wind non uniformity in space shifts southwestward with eddy motion along the continental slope these new findings from satellite observations give us an opportunity to study oceanic eddy s roles in ocean atmosphere interaction on weather timescales

atmospheric manifestation of tropical instability wave observed by quikscat and tropical rain measuring mission observations from two new spaceborne microwave instruments in 1999 clearly reveal the atmospheric manifestation of tropical instability waves north of the pacific equatorial cold tongue a unique zonal temporal band pass filter enables the isolation of the propagating signals and the determination of their phase differences the phase differences between the propagation of wind and sea surface temperature sst signals observed from space and the vertical wind profiles measured from a research ship are consistent with the hypothesis that the coupling between wind and sst is caused by buoyancy instability and mixing which reduces the wind shear in the atmospheric boundary layer the coupling causes higher evaporative cooling over the warm phase and infers a negative thermal feedback

observed cold filaments associated with mesoscale eddies in the south china sea unusual cold filaments are uncovered during the spring intermonsoon season in the south china sea scs using a suite of satellite observations they have a width of about 100 km on average and extend several hundreds of kilometers offshore on the sea surface providing significant cross shelf transport of heat and nutrients the eastward current associated with mesoscale eddies in spring in the western scs is found to play an important role in the filament formation by advecting coastal cold waters far offshore the meridional location of the cold filament displays considerable interannual variability ranging between 9on and 18on which can be attributed to the interannual south north shift of the eastward current associated with eddies it is also found that in the spring cold filaments have profound effects on the chlorophyll a concentration in the upper ocean and the overlying atmosphere these findings provide new insights into the role of eddies in cross shelf exchange and mesoscale air sea interaction in the marginal seas

influence of mechanical mixing on a low summertime sst in the western north pacific itcz region 1 a region with a low sea surface temperature sst was identified in the western north pacific wnp intertropical convergence zone itcz or warm water pool region in boreal summer the sst decreases by up to 0 5 c from may to the june july august jja season just east of mindanao island analyses of the observed data indicated that a northeastward surface current constantly exists throughout the year supplying cold subsurface water through the molucca strait as a result the subsurface water is colder by several degrees compared with that in the surrounding regions the sea surface wind is strong over this region in the jja season examination of argo float data demonstrated that the mixed layer becomes deeper from may to the jja season it is suggested that the strong wind causes vertical mixing between the surface and subsurface layers resulting in the low summertime sst

petrogenesis of archaean trondhjemites tonalites and granodiorites from eastern finland major and trace element geochemistry

an airborne expendable bathythermograph survey of the south china sea may 1995 an extensive airborne expendable bathythermograph survey of the south china sea scs conducted in may 1995 and historical data are used to analyze and infer the upper layer 300 m synoptic structure and general circulation the primary thermal feature observed was a central scs warm pool surrounded by several cool pools the size of the warm pool decreased with depth from approximately 200 000 km2 at 50 m depth to about 70 000 km2 at 300 m depth the maximum temperature of the warm pool was 30 c appearing near the surface at the depth of 50 m the temperature of the central scs warm pool was 29 c and the temperature of the five surrounding cool pools ranged from 26 c to 22 c a three dimensional estimate of the absolute velocity field was obtained from the observed temperature field and a climatological salinity field using the spiral method striking circulation features were the existence of dual anticyclonic eddies in the central scs warm pool and the existence of cyclonic eddies associated with the cool pools in the upper layer the tangential velocity of the dual central scs anticyclonic warm core eddies is around 30 40 cm s and that of the five cyclonic cool core eddies varies from 10 cm s to 40 cm s the tangential velocity of all the eddies decreased with depth at 300 m depth it became less than 5 cm s for all the eddies

observations of coupling between surface wind stress and sea surface temperature in the eastern tropical pacific satellite measurements of surface wind stress from the quikscat scatterometer and sea surface temperature sst from the tropical rainfall measuring mission microwave imager are analyzed for the three month period 21 july 20 october 1999 to investigate ocean atmosphere coupling in the eastern tropical pacific oceanic tropical instability waves tiws with periods of 20 40 days and wavelengths of 1000 2000 km perturb the sst fronts that bracket both sides of the equatorial cold tongue which is centered near 1 8s to the east of 1308w these perturbations are characterized by cusp shaped features that propagate systematically westward on both sides of the equator the space time structures of these sst perturbations are reproduced with remarkable detail in the surface wind stress field the wind stress divergence is shown to be linearly related to the downwind component of the sst gradient with a response on the south side of the cold tongue that is about twice that on the north side the wind stress curl is linearly related to the crosswind component of the sst gradient with a response that is approximately half that of the wind stress divergence response to the downwind sst gradient the perturbed sst and wind stress fields propagate synchronously westward with the tiws this close coupling between sst and wind stress supports the wallace et al hypothesis that surface winds vary in response to sst modification of atmospheric boundary layer stability