a method for the determination of nitrogen in clays with application to the burial diagenesis of shales a new operationally defined method for the measurement of fixed inorganic nitrogen n sub fix associated with clays has been tested and applied to a sequence of mixed layer illite smectite i s ranging from 40 to 68 illite in i s in shales from a drill site in terrebonne parish louisiana this new method has distinct advantages over other methods in that it is simple and can accommodate small sample sizes 10 mg n sub fix is measured using a carbon nitrogen analyzer on a sample that has been ashed for 8 hr at 450 c to remove organic and non fixed inorganic nitrogen total nitrogen is measured on an separate untreated sample content of organic carbon and nitrogen can be assessed by the weight percent difference between untreated and ashed samples fourier transform infrared spectroscopy confirmed the presence of nitrogen as ammonium in untreated and heat treated samples n sub fix content of the 0 2 mu m fraction of the shale sequence correlates positively r sup 2 0 91 with the percent of illite in the mixed layer i s corresponding with the increase in percent of illite in i s with depth an increase in n sub fix content is also seen with increasing depth of burial nitrogen from thermal breakdown of organic matter duringmore later diagenesis probably provides the n sub fix found in i s in the range of diagenesis studied here n sub fix concentration appears to depend on the available fixing capacity of illite because nitrogen content varies with organic matter type however caution should be used when assuming this relationship for other diagenetic environments less

recent current observations in the eastern yellow sea observations of current velocity pressure and temperature in the eastern yellow sea from january 10 through april 12 1986 together with geostrophic winds calculated from surface atmospheric pressure distributions are analyzed for a study of the synoptic band response of the yellow sea to the wintertime winds north wind pulses in the winter monsoon are found to give rise to northward flow bursts in the yellow sea trough which appear to peak just as the wind relaxes and to be driven by a synoptic band north to south rise in bottom pressure synchronous with the north wind pulses the existence of a similar rise in coastal sea level indicates that the observed southward pressure rise is but an offshore extension of a setup along the west coast of south korea forced by the north wind pulses the advection by northward flow bursts of warm water from the south apparently causes the measured temperature to be substantially higher in the trough than in coastal waters at the same latitude and the observed rate of cooling in the trough to be less than half of that in coastal waters to the east a winter to spring transition is also found in the bottom pressure records obtained in the trough in which the mean north to south gradient in winter reverses suddenly in early march a similar reversal also appears in sea level records along the west coast of south korea the reversal appears to be triggered by the weakening of the north winds at the arrival of spring

diffusive retention of carbon and nitrogen in a microcrystalline quartz dominated chert implications for reconstructing earth s ancient atmosphere abstract we investigate the retention of volatile species and we analyze the volatile species released on low temperature crushing of a microcrystalline quartz

current observations on the development of the yellow sea warm current historically the climatological mean northward flow in the yellow sea trough has been referred to as the yellow sea warm current yswc since it was thought to originate as a branch of the tsushima current which transports warm kuroshio waters however the tsushima current does not penetrate into the yellow sea interior during winter the onset of what is referred to as the yswc during winter is directly observed using measurements of current profiles pressure and temperature and a wind climatology for the time period july 1995 through january 1996 the yswc is a result of weak southerly winds during summer during fall transition and winter monsoon periods strong northerly wind bursts drive a north to south rise in pressure extending from the trough over to the korean coast and force a northward flow in the yellow sea trough the rise in pressure and corresponding north wind forced yswc begin at the end of october for this measurement period and are observed into january these measurements show that the yswc has different seasonal forcing mechanisms direct current measurements are also presented which suggest a current flow north of cheju sometimes referred to as the cheju warm current

wind driven effects on the yellow sea warm current the yellow sea is a shallow basin writh an average depth of 44 m located between china and the korean peninsula one of the dominant ocean circulation features of the yellow sea is a warm wrater intrusion known as the yellow sea warm current this feature is present throughout the year but reaches its farthest northward extension in winter the circulation of the yellow east china and bohai seas was modeled using the princeton ocean model to better understand the dynamics of the yellow sea warm current the horizontal resolution of the model varies from 8 km in the yellow sea to 25 km in the east china sea twenty four sigma levels are used to define the vertical structure the model uses daily atmospheric forcing from the navy operational global atmospheric prediction system for 1993 open boundary conditions are applied at the taiwan strait the tsushima korea strait an area south of taiwan and the tokara strait with a closed boundary south of the ryukyu islands the model results are examined to determine the effect of the wind on the northward extension of the warm water intrusion using both water mass characteristics and northward velocity components sensitivity tests and spectrum analyses performed to study the influence of the wind on the yellow sea warm current show that winds modify the pathway and extent of the yellow sea warm current the current s origin however appears to be due to external forcing from the current systems developed in the east china sea

an asymmetric upwind flow yellow sea warm current 2 arrested topographic waves in response to the northwesterly wind 1 a warm and salty water mass exists along the yellow sea trough yst in winter this oceanic water mass is distinct from the ambient shelf water and is distributed on the western side of the yst it has long been reasoned that a yellow sea warm current yswc must exist a recent observational study indeed supports the existence of the yswc and shows that its position moved progressively westward as the warm water intrudes further shoreward toward the northwest in this paper we explain mechanisms for sustaining the yswc and for its westward displacement the northwesterly monsoonal wind prevails in the winter and is directed against the yswc the cross trough scale is small compared with the spatial scale of monsoonal variation so one can assume to the first order that the wind stress is uniform across the trough the curl of depth averaged wind stress has opposite signs on the two sides of the trough consequently two oppositely rotating gyres develop initially and they converge along the trough giving rise to a barotropic upwind flow but this upwind flow lasts only for a few days as the two gyres evolve and propagate as topographic waves for a northerly wind both gyres move westward since the positive negative potential vorticity flux on the western eastern side of the trough pushes the water toward shore trough if the bottom friction is negligible the steady response becomes a large anticyclonic gyre over the trough and the upwind current is squeezed toward the shore line in this case no yswc is sustained along or near the trough this runaway warm current can be arrested by a moderate bottom friction we therefore propose that the yswc is actually arrested topographic waves in response to local wind stress forcing

a field study of the chemical weathering of ancient sedimentary organic matter weathering profiles developed on organic carbon rich black shales were studied to examine the loss and degradation of organic matter om during weathering and its role in the geochemical carbon cycle analysis of weathered shales reveals between 60 and nearly 100 total organic carbon toc loss in highly weathered samples relative to initial unweathered toc content pyrite loss coincides with or precedes organic carbon loss elemental analysis and flash pyrolysis gas chromatography py gc of kerogen concentrates indicate that there is little or no selective enrichment or depletion of norg containing sorg containing alkylaromatic branched alkyl or long chain n alkyl moieties in most profiles during weathering kerogen o c ratios consistently increase with toc and pyrite loss infrared spectroscopy ir reveals an increase in the relative abundance of c c and c o bonds relative to alkyl c h bonds in progressively weathered samples these results suggest a two component model for kerogen weathering largely non selective oxidation and hydration followed by cleavage dissolution of oxidized kerogen fragments the extent of weathering in a given outcrop is likely limited by a combination of the rate of physical erosion and exposure of the rock to oxidizing surface waters with om type composition playing a lesser role

occurrence of large temperature inversion in the thermohaline frontal zone at the yellow sea entrance in winter and its relation to advection temperature inversion higher temperature at a deeper depth in winter and its relation to advection were investigated by analyzing both conductivity temperature depth data in the southern yellow sea ys and northwestern east china sea during the winter of 2002 2003 and time series data of temperature salinity and currents at a buoy station at the ys entrance significant temperature inversions occur predominantly along the thermohaline front at the ys entrance where the cheju warm current water cwcw and the cold coastal waters meet in february 2003 on the northern frontal zone along 34 n where isotherms and isohalines declined downward to the north particularly large inversions with temperature differences of larger than 2 0 c were observed to occur more in troughs than in the crests of the wave like frontal meander where the cold korean coastal water kcw advances farther southward the inversion persisted until mid april at the buoy station in the frontal zone and both temperature and salinity showed simultaneous variations in the same manner during episodic occurrences of large inversions temperature and salinity decreased sharply in the upper layer but increased concurrently in the lower layer these episodic inversions were found to be closely related to the westward advection of the kcw in the upper layer and the northward advection of the cwcw in the lower layer it is considered that these advections may play an important role in maintaining baroclinicity in the northern frontal zone which is responsible for driving the westward transversal flow across the ys entrance

15 n depleted nitrogen in early archean kerogens clues on ancient marine chemosynthetic based ecosystems a comment to beaumont v robert f 1999 precambrian res 96 62 82

source and possible leaching process of ore metals in the uragen sandstone hosted zn pb deposit xinjiang china constraints from lead isotopes and rare earth elements geochemistry abstract the uragen world class zn pb deposit is located in the ulugqat basin in xinjiang china the deposit is characterized by low grade zn pb 3 wt and large tonnage of 4 84 mt metals in the southern ore zone and potentially 10 mt metals for the whole deposit the deposit is mainly hosted in sandstone and conglomerate of the fifth member of the lower cretaceous kezilesu group to provide better constraints on the source of ore metals systematic analyses of the pb isotopes and ree were conducted on sulfides and possible source terranes the sulfides have homogeneous pb isotopic ratios for 206pb 204pb of 18 528 18 690 for 207pb 204pb of 15 545 15 743 and for 208pb 204pb of 38 429 39 082 these ratios are different from those of the upper silurian upper devonian tangaitaer and paleocene aertashi formations the fourth member of the lower cretaceous kezilesu group and the permian granite despite partly overlapping with the values of sulfides the ratios of the proterozoic aksu metamorphic rocks are different in extent and variability however the clastic rocks of the fifth member of the lower cretaceous kezilesu group have almost the same pb isotopic compositions as the sulfides if the preferential leaching of radiogenic pb is taken into account the sulfides in the disseminated ores show lree enriched patterns with high lree hree ratios 3 50 12 06 variable changes of ce anomalies 0 67 1 22 and eu anomalies 0 52 1 33 that are also similar to those of the clastic rocks of the fifth member of the lower cretaceous kezilesu group but are significantly different from those of the basement rocks of the proterozoic aksu group and the evaporite sequences of the paleocene aertashi formation in the ce and eu anomalies petrographic observations indicate that the clastic rocks of the fifth member of the lower cretaceous kezilesu group have undergone sedimentation diagenetic reddening and bleaching reddening is related to the in situ oxidation of mafic minerals such as biotite to produce ferric iron oxide and hydroxide ioh that accompanied the liberation of ore metals from the silicate phase during subsequent crystallization of ioh to hematite preferential adsorption onto hematite could have been the main mechanism for separating zn pb from cu bleaching resulted from the dissolution of ioh during the oil gas infilling stage and based on mass balance calculations substantial amounts of leachable fe zn pb were extracted from the red clastic rocks by the ore forming fluid therefore we propose that the red clastic rocks of the fifth member of the lower cretaceous kezilesu group may be the predominant source of ore metals in the uragen deposit and that the leaching may be possibly related to the bleaching process

westward shift of the yellow sea warm salty tongue 1 the accumulated in situ hydrographic survey as well as the satellite observed sea surface temperature sst show consistent westward shifting of the yellow sea warm salty tongue yswst in winter a 2 d thermal model is used to show the westward shifting of the yswst due to cooling and advection the mitgcm is applied to simulate the circulation in the yellow and east china seas under the northern monsoon wind in winter the sea surface height ssh is adjusted to have a ridge in the channel and a trough in the 50 70 m iso bath in the yellow sea the barotropic transport of ssh and baroclinic transport of horizontal density gradient play the major role for the shifting of the yswst while the ekman wind drift plays a minor role

nitrogen in rock occurrences and biogeochemical implications 1 there is a growing interest in the role of bedrock in global nitrogen cycling and potential for increased ecosystem sensitivity to human impacts in terrains with elevated background nitrogen concentrations nitrogen bearing rocks are globally distributed and comprise a potentially large pool of nitrogen in nutrient cycling that is frequently neglected because of a lack of routine analytical methods for quantification nitrogen in rock originates as organically bound nitrogen associated with sediment or in thermal waters representing a mixture of sedimentary mantle and meteoric sources of nitrogen rock nitrogen concentrations range from trace levels 200 mg n kg 1 in granites to ecologically significant concentrations exceeding 1000 mg n kg 1 in some sedimentary and metasedimentary rocks nitrate deposits accumulated in arid and semi arid regions are also a large potential pool nitrogen in rock has a potentially significant impact on localized nitrogen cycles elevated nitrogen concentrations in water and soil have been attributed to weathering of bedrock nitrogen in some environments nitrogen released from bedrock may contribute to nitrogen saturation of terrestrial ecosystems more nitrogen available than required by biota nitrogen saturation results in leaching of nitrate to surface and groundwaters and where soils are formed from ammonium rich bedrock the oxidation of ammonium to nitrate may result in soil acidification inhibiting revegetation in certain ecosystems collectively studies presented in this article reveal that geologic nitrogen may be a large and reactive pool with potential for amplification of human impacts on nitrogen cycling in terrestrial and aquatic ecosystems

the pedogenic formation of coal balls by co2 degassing through the rootlets of arborescent lycopsids coal balls are calcium carbonate accumulations that permineralized peat in paleotropical permo carboniferous 320 250 ma mires the formation of coal balls has been debated for over a century yet a widely applicable model is lacking two observations have been particularly challenging to explain 1 the narrow temporal occurrence of coal balls and 2 their typical elemental high mg and isotopic low 18o composition that paradoxically indicate marine and freshwater origins respectively we evaluate a new model in which coal balls formed as co2 escaped from the peat by diffusion through unusual air filled spaces in the rootlets of lycopsid trees critically these trees were very common in paleotropical mires and their evolutionary range matches the temporal range of coal balls the episodic delivery of seawater and marine carbonate sediment to coastal mires is the first step in our model although other pathways for the delivery of divalent cations are permissible subsequent dilution by freshwater and dissolution of these carbonates at the elevated co2 of the mire subsurface is followed by the transport of co2 through the rootlet airspaces and into the overlying water and atmosphere which drives carbonate mineral precipitation in the sediment we show that dilution by freshwater because it minimally affects mg ca ratios can result in relatively low pore water 18o values while allowing high mg calcite formation this model thus explains the restriction of coal balls to the permo carboniferous and resolves the discrepancy between elemental and isotopic compositions of coal ball carbonate minerals furthermore we show with a 3d reactive transport model that co2 could escape rapidly enough through the rootlets to fill 25 percent of the peat pore spaces with calcite before substantial burial top decimeter of peat explaining the exceptional preservation of coal swamp flora therefore we suggest that coal balls are pedogenic in origin and that the disappearance of these pedogenically permineralized histosols represents the first documented decrease in soil diversity on a vegetated planet the rock record may thus provide important context for the modern loss and degradation of soils

two layer tidal modeling of the yellow and east china seas with application to seasonal variability of the m2 tide 1 the baroclinic response of tide and tidal currents in the yellow and east china seas is investigated using a two layer numerical model seasonal variability in the m2 tide especially the smaller summer amplitudes prevailing along the korea tsushima strait kang et al 1995 is investigated by a series of numerical experiments with varying degrees of stratification specific to winter and summer model results show that the summer amplitudes of the m2 tide around the southwestern tip of the korean peninsula and korea tsusima strait decrease with a peak decrease of about 14 cm off the southwestern tip of the korean peninsula while the summer amplitudes in other coastal regions tend to increase this seasonal variability generally coincides with the observations these models results indicate that seasonal stratification has several noticeable effects on the tides including varying degrees of current shear varying frictional dissipation and varying barotropic energy flux in particular it drives complicated seasonal variability in the m2 tide with a peak amplitude modulation of nearly 5 off the southwestern tip of the korean peninsula the seasonal variation of barotropic m2 energy flux through the eastern entrance of the yellow sea is thought to induce the corresponding variability in the m2 amplitude in the korea tsusima strait with smaller amplitudes found in the summer

nitrogen in future biosphere studies this article suggests a theme for future nitrogen studies involving the functioning and evolution of the biosphere together with certain aspects of human biology it is hoped that this theme could be developed into a multi authored book at some point in the future although numerous new case studies may be required the biosphere can be considered to be a single interactive system comprised of numerous component parts including the atmosphere rain rivers lakes oceans continental ecosystems marine ecosystems soils and sediments in order to study the internal complexity of each of the components and the relationships that exist between them one can choose a common theme the author believes that nitrogen is a good prospect because of its ubiquitous nature and complex chemistry the burial of sedimentary volatiles in the continental crust has contributed to the long term chemical evolution of the exterior environments of the earth the most marked effects notably the accumulation of atmospheric oxygen have been due to the burial of reduced carbon an understanding of the passage of sedimentary volatiles through the crust will provide important constraints on the evolution of the biosphere and may lead to a more meaningful comparative planetology carbon is difficult to trace through crustal processes because its high temperature form graphite is incompatible with the crystal structures of silicate minerals however the high temperature form of sedimentary nitrogen ammonium readily enters into potassic minerals and it can be easily traced through crustal processes herein the fate of sedimentary nitrogen is traced from wet sediments through metamorphic rocks into granites and other crustal melts without the trapping of nitrogen in the crust and the liberation of oxygen that is a consequence of biological nitrogen fixation the n2 o2 of the atmosphere may have been about 82 9 to 16 3 and the total atmospheric pressure about 1 2 atm most of the changes in the oxygen content is due to dilution by nitrogen with only about 5 of the present atmospheric oxygen being a consequence of nitrogen fixation the ancient continental surfaces would have been volcanic deserts containing little 1 ppm or no nitrogen today nitrogen rich soils support continental ecosystems one can use nitrogen as a window to speculate on the colonisation of the continents by land plants herein nitrogen fixation by legumes is considered in detail and by drawing analogies with the present day the author speculates on the colonisation of the continents by land plants having speculated on the co evolution of the atmosphere soils and continental ecosystems one can place a human being in the centre of a tropical forest and begin to examine how they relate to the modern biosphere the chosen example is the metabolism of plant protein and the roles of glutamate dehydrogenase gdh vitamin b2 and flavin mononucleotide fmn the realisation of this theme would imply numerous new case studies notably those concerning the continental crust where nitrogen studies were linked to mineralogy petrology and other geochemical tracers including sr o al and k and where the short range order of 15n were taken into consideration

clay mineral authigenesis in coal and shale from the anthracite region pennsylvania textural chemical and mineralogical analyses of authigenic clays in anthracite rank coal and associated shale from eastern pennsylvania have allowed a better understanding of the parameters controlling diagenesis and perhaps coalification in this region minerals in anthracite occur in distinct assemblages associated with the following microenvironments coal matrix two orthogonal joint sets termed systematic and nonsystematic cleat and a third joint set mineralogical differences among microenvironments allow inferences about clay mineral origins and the parameters that controlled mineral authigenesis kaolinite occurs in the shale and all microenvironments within the coal seam authigenic minerals that replaced preexisting kaolinite during the latest stage ofcoalification anthracitization at t 200 c include nhu rich illite pyrophyllite and the following minerals which are primarily restricted to the systematic cleat set tosudite rl ordered dioctahedral mixed layer chlorite smectite sudoite di trioctahedral chlorite and rectorite rlordered mixedjayer paragonite smectite alteration of smectite to illite may be responsible for formation of authigenic illite and na bearing illite which are present only in the shale and coal matrix and fe al rich chlorite and quartz in the third joint set the chemical components for authigenesis appear to have multiple sources ai and si from preexisting kaolinite and quartz n from local organic matter mg and na for tosudite sudoite and rectorite largely from metasomatic hydrothermal fluids fe and mg for fe al rich chlorite from smectite illitization minerals in the shale the coal matrix and the nonsystematic cleat set are interpreted to represent authigenesis in a low permeability environment closed system alteration however the assemblage sudoite tosudite rectorite in the systematic cleat set is interpreted to be the result ofone or two stages ofhydrothermal alteration open system alteration we suggest hat differences in minerals between the two nearly perpendicular cleat sets are the result of permeability differences which were maintained by an anisotropic lateral stress field created by plate convergence during the alleghanian orogeny hydrothermal alteration may be related to large scale basinal flow induced by alleghanianage uplift such migrating fluids could also have transported heat from depth and thereby significantly increased the rate and rank ofcoalification in this region

pyritic shales and microbial mats significant factors in the genesis of stratiform pb zn deposits of the proterozoic extensive horizons of pyritic shale occur in mid proterozoic sediments of the eastern belt basin montana u s a these pyritic shales are of striped appearance laminated pyrite beds alternate with nonpyritic shale beds laminated pyrite beds have wavycrinkly internal laminae and are interpreted as mineralized microbial mats pyrite is essentially the only sulfide mineral in these shales pyritic shale horizons occur along the basin margins and it is feasible that colloidal iron was introduced by rivers into basin marginal lagoons and then incorporated into microbial mats and reduced to pyrite the pyritic shales in the newland formation show great similarity to those that host the pb zn deposits of mt isa and mcarthur river it is suggested that pyritic shales of this kind are relatively common in mid proterozoic shales and that the processes that led to the occasional formation of pb zn ore bodies in these shales are not related to those that formed the pyritic shales themselves

the cycling and redox state of nitrogen in the archaean ocean organisms that produce oxygen through photosynthesis existed during the late archaean eon about 2 500 million years ago but controversial evidence suggests that they may have evolved several hundred million years earlier oxygen is expected to react with oceanic nitrogen altering its redox state the reaction leaves a signature in the isotopic composition of the nitrogen bound in organic matter here we present a record of the nitrogen isotopic composition of kerogen extracted from minimally altered shales from the campbellrand malmani platform in south africa between the palaeo archaean and about 2 670 million years ago the 15n values of the kerogen rose by about 2 we interpret this increase as an indication of the onset of coupled nitrification and denitrification or anammox reactions in the surface oceans which require the presence of free oxygen a second increase in nitrogen isotopic composition around 2 520 million years ago implies instability of the n cycle with loss of fixed n this evidence for available oxygen in the oceans occurs at least 200 million years before geochemical indications of the presence of significant levels of atmospheric oxygen we suggest that coupled nitrification and denitrification drove the loss of fixed inorganic nitrogen leading to nitrogen limitation and conclude that the low levels of biologically available nitrogen limited the growth of oxygen producing plankton delaying the accumulation of oxygen in the atmosphere the initial production of oxygen in early earth s oceans altered the redox chemistry and cycling of nitrogen a record of nitrogen isotopes from preserved organic matter indicates nitrogen cycling in the presence of free oxygen 2 67 billion years ago about 200 million years before the first geochemical evidence for atmospheric free oxygen

can humans force a return to a cretaceous climate abstract the modern pole to equator sea level temperature difference is about 50 c that of the mid cretaceous ranged from 30 c to as little as 24 c implying a much more equable climate this may have been caused by 1 reduction of the ice forced albedo of the polar regions 2 more efficient meridional energy transport by the atmosphere and ocean and 3 increased atmospheric greenhouse gas concentrations earth s icy polar regions stabilize its present inequable climate through the ice albedo feedback effect the polar ice results in permanent atmospheric highs that stabilize earth s wind systems in turn the stable winds drive the ocean currents and determine the location of the frontal systems that separate the low and high latitude oceanic gyre systems and bound the region where water sinks into the ocean interior as thermocline and intermediate water masses increased ocean heat transport can assist in making a more equable climate but unrealistic volume transports would be required to warm the polar regions to cretaceous levels the major factor forcing the equable climate of the cretaceous is now thought to be increased greenhouse gas concentrations dominated by co2 the modern rate of change in atmospheric concentration is greater than 200 ppmv per century and increasing this compares with 1 ppmv per century during the last deglaciation at current rates of fossil fuel burning atmospheric co2 levels will reach cretaceous levels of 2 times the pre industrial level about 2070 and 8 times the pre industrial level shortly after 2300 it is likely that cretaceous atmospheric co2 concentrations will last for many thousands to tens of thousands of years in addition to increased atmospheric greenhouse gas concentrations a return to climatic conditions resembling those of the cretaceous would require ice free poles and large changes in atmospheric and oceanic circulation arctic sea ice is melting much more rapidly than had been expected and the arctic ocean will soon be free of sea ice in summer the greenland ice sheet is melting more rapidly than expected because of greenhouse warming surface meltwater forms lakes and then flows down through crevasses and holes in the ice to lubricate the base allowing ice steams to flow much more rapidly the lifetime of the greenland ice sheet may be only a few hundred years the west antarctic ice sheet is inherently unstable being grounded on rock well below sea level the ice shelves blocking ice streams off west antarctica have begun to melt from beneath and break up as the southern ocean warms the east antarctic ice sheet has been regarded as highly stable but discovery of lakes beneath the ice and fast flowing ice streams raises questions about whether the ice sheet will ultimately succumb to global warming and disintegrate i conclude that a return to climatic conditions resembling those of the mid cretaceous is not only possible but also likely unless humanity can organize an effective campaign to stop co2 emissions to the atmosphere and remove some of the excess co2 already introduced

coastal circulations driven by river outflow in a variable density 1 layer model a variable density 1 layer model is used to investigate the dynamics of the fresher water plumes generated by river outflow solutions are found in a north south channel and the transport mr and salinity sr of the outflow are specified as boundary conditions along a 25 km wide segment of the western boundary in most cases the river water discharges into a preexisting oceanic mixed layer with thickness h1 when mr is sufficiently low plumes remain coastally trapped immediately after the outflow is switched on a coastal kelvin wave is excited at the river mouth that establishes a southward current of oceanic water along the right hand coast in contrast all the river water first bends to the left as it exits the river mouth and the resulting plume advances northward along the left hand coast at the plume nose some of the fresher water reverses direction and this water together with some oceanic water flows southward on either side of the offshore density front between the fresher and salty waters two processes cause this upstream movement geostrophic adjustment generates the southward frontal current and kelvin wave propagation from the nose thins the layer within the plume thereby establishing the northward geostrophic coastal jet when mr is sufficiently high coastally trapped plumes no longer exist if the rossby number of the outflow is also large enough the river water flows directly offshore and only a portion of it recirculates to form a northward propagating coastal plume the angle at which the outflow leaves the river mouth becomes more southward as mr and sr increase and as h1 decreases the strength of the northward propagating plume is weakened as h1 decreases and sr increases when h1 0 so that there is no ambient oceanic layer there is no northward plume at all likewise the plume is weakened when the model includes entrainment a process that acts to prevent the layer thickness from thinning appreciably

three dimensional wind driven flow in an elongated rotating basin abstract the wind driven circulation in lakes lagoons estuaries or coastal embayments is described with a linear steady three dimensional barotropic model in an elongated basin of arbitrary depth distribution on an f plane with rotation the vertically averaged velocity scales with the ekman depth rather than the maximum depth h0 as in the case without rotation near the closed ends of the basin the flow turns in viscous boundary layers because the length of the turning areas depends on the sign of the bottom slope and on the ratio of the ekman depth to h0 there is a striking contrast between the turning areas on either side of an observer looking toward the end of the basin in the northern hemisphere the turning area on the left is broad of order 1b where b is the basin half width the turning area on the right is narrow of order b and dynamically equivalent to the western boundary current in models of the wind driven ocean circulation ekman solutions are used to describe the ve

organic geochemistry of the san vicente zinc lead district eastern pucara basin peru abstract isotopic and chemical studies of organic matter of the san vicente mississippi valley type zn pb district hosted in the dolomitic units of the eastern pucara basin peru provide insight into the source of organic matter and of the organic matter ore relationship a large scatter exists in the 13c and 15n values of the highly mature kerogens these bulk data were combined with 13c covariations of the saturated and aromatic fractions of the rock extracts to indicate a contribution of continental higher plant lipids to the marine algal source of the organic matter disseminated in the host carbonate rocks an enrichment in 15n of the kerogens of mineralized samples compared to barren samples suggests that isotopically heavy nitrogen compounds were introduced to the ore fluid the fluid likely leached these compounds from the underlying clastic rocks and other detrital units of the pucara the extracts from mineralized samples are enriched in 13c compared to the associated kerogens this suggests that the rocks in the mineralized areas were stained by a mixture of extrinsic and indigenous bitumens by the use of novel instrumentation such as a gas chromatograph gc coupled to a stable isotope ratio mass spectrometer irms through a combustion c interface gc c irms stable carbon isotope analyses of individual hydrocarbons were also obtained both the molecular and isotopic signatures of the individual hydrocarbons are related to mineralization the variability in the organic molecular parameters and the 13c values of the individual n alkanes and isoprenoids indicate mixing of indigenous hydrocarbons with extrinsic 13c depleted microbially derived hydrocarbons the extrinsic source hydrocarbons were introduced to the mineralization site by the ore fluid or later fluids using the same porosity network oxidative alteration of the migrating hydrocarbons was involved in the thermochemical reduction of sulfate to h2s and precipitation of pyrobitumen large differences 12 in the carbon isotope compositions of long chain c20 n alkanes can be utilized in distinguishing sources of organics in the barren and mineralized samples

the origin and economic potential of sandstone hosted disseminated pb zn mineralization in pyritic shale horizons of the mid proterozoic newland formation montana usa pyritic shale horizons of the newland formation belt series mid proterozoic show striking similarities to proterozoic pyritic shales elsewhere that are host to major lead zinc deposits such as mt isa and mcarthur river however in contrast to these deposits the pyritic shales of the newland formation contain only minute quantities of lead and zinc elevated concentrations of lead and zinc are only found in pore spaces of intercalated sandstone beds petrographic and geochemical data indicate that pyritic shale deposition and elevated lead zinc concentrations in sandstone beds are unrelated that base metal mineralization is controlled by initial porosity and that iron and base metals were derived from different sources

eolianite grain size distributions as a proxy for large changes in planetary atmospheric density a digitized version of the ahlbrandt 1979 global dune dataset and data for distributions in figure are available at https github com erikgoosmann aeoliandata

numerical investigation of the generation of continental shelf waves and their role in the westward shift of the yellow sea warm current abstract the yellow sea warm current yswc which carries warm saline water into the yellow sea ys exhibits a typical northward upwind flow during winter observations have shown that the path of the yswc has shifted to the west from the deep trough and it has been suggested that continental shelf waves csws may play an important role in this westward shift however the source of southward propagating csws that drive the westward shift of the yswc remains unclear the objective of this study is to reveal the generative mechanism of csws and their role in driving the westward shift of the yswc numerical models with an idealised topography show that the westward shift of the northward flow propagates southward along the western slope offshore of china with a typical speed of 2 99 m s 1 comparable to the theoretical phase speed of a first mode csw csws driving the westward shift are generated on the northern slope primarily by the scattering of kelvin waves that develop due to northerly winds and propagate northward into the ys along the eastern boundary of the korean peninsula model experiments with a realistic topography consistently support the idea that kelvin wave scattering is a primary source of the southward propagation of the csws that drive the westward shift of the yswc

origins of stratiform and stratabound fe cu zn horizons in the lower proterozoic moran lake group labrador central mineral belt zn cu and fe are concentrated as stratiform and stratabound sulphide rich beds in the lower proterozoic warren creek formation moran lake group central labrador upper member sedimentary rocks have a hydrothermal like fe enrichment but a dominantly hydrogenous signature as indicated by high al2o3 relative to sio2 and high al and fe relative to mn the upper member shales and sulphide rich beds were deposited as fe rich pelagic sediments the paucity of mn and abundance of fe in typical shale samples and lack of cu pb and zn fractionation in stratiform massive sulphide beds that contain up to 4702 ppm zn 533 ppm cu and 15 ppm pb suggest that deposition occurred in restricted brine pools i e cu and zn were precipitated rapidly and were not fractionated stratabound sphalerite mineralization containing 3 7 zn and 121 ppm cu but no pb was deposited in a porous lithology at the top of the warren creek formation and represents a unique style of metal concentration the stratiform deposits proba

the effect of long term atmospheric changes on the macroevolution of birds abstract atmospheric conditions are critical for a range of biological functions locomotion among others and long term changes in these conditions have been identified as causal for different macroevolutionary patterns here we examine the influence of variations in atmospheric o2 concentration aoc temperature tair and air density air on the power efficiency as it relates to locomotion during the evolutionary history of birds specifically our study centers on four key evolutionary events 1 the body mass reduction of non avian theropods prior to the rise of birds 2 the emergence of flapping flight in the earliest birds 3 the divergence of basal pygostylians and 4 the diversification of modern birds our results suggest that a marked increase in aoc and air during the middle jurassic coeval with a trend in miniaturization improved the power efficiency of the dinosaurian predecessors of birds likewise an increase in these conditions is hypothesized as having played a major role in the diversification of early pygostylians during the early cretaceous however our analyses do not identify any significant paleoatmospheric effects on either the emergence of flapping flight or the early cladogenesis of modern birds extinct birds flew within the range of atmospheric conditions in which modern birds fly but varying past conditions influenced their flight performance our study thus highlights the importance of considering paleoatmospheric conditions when reconstructing the flight efficiency of the forerunners of modern birds

geological nitrogen cycle and atmospheric n2 over phanerozoic time using the average nitrogen carbon ratio n c of sedimentary organic matter coal and volcanic metamorphic gases existing models of the carbon cycle have been used to calculate the fluxes of nitrogen to and from the atmosphere via the weathering burial and metamorphic volcanic decomposition of organic matter results indicate no appreciable change less than one percent of that present in the mass of atmospheric n 2 over phanerozoic time this is in sharp contrast to atmospheric o 2 which shows notable variations variation of the mass of o 2 but not that of n 2 must have led to variation in total atmospheric pressure with time results are not altered by considering n c ratios ten times higher than the average for sedimentary rocks nor by considering nitrogen release from silicate weathering the residence time of n 2 in the atmosphere relative to exchange with and storage in crustal rocks is estimated to be about one billion years

polymetallic mineralization at the browns deposit rum jungle mineral field northern territory australia the rum jungle mineral field northern territory australia forms part of the paleoproterozoic pine creek orogen the geology of the area comprises two archean granitic basement domes overlain by a paleoproterozoic sequence of metasedimentary and subordinate metavolcanic rocks the rocks have been deformed and metamorphosed to greenschist facies during the 1880 ma barramundi orogeny but the original stratigraphic succession has been preserved the browns deposit browns and its extension browns east hosted within black carbonaceous pelites of the paleoproterozoic whites formation is the largest base metal deposit found to date in the pine creek orogen present resource estimates are 39 million metric tons mt at 0 44 percent cu 3 61 percent pb 0 11 percent co and 0 09 percent ni browns and 31 mt at 1 29 percent cu 1 28 percent pb 0 13 percent co and 0 13 percent ni browns east major sulfide minerals in the ore zone are galena sphalerite chalcopyrite pyrite and the main carrier of ni and co siegenite ni co 3 s 4 digenite group minerals and bornite ca bearing plumbogummite pbal 3 po 4 2 oh 5 h 2 o arsenopyrite and gersdorffite are present in minor quantities ore minerals occur as fine grained wisps parallel to the main bedding parallel foliation and as coarse grained mono and polyminerallic aggregates that crosscut the foliation total noncarbonate carbon contents of unaltered rocks range from 1 07 to 7 51 wt percent total sulfur contents range from 2 13 to 6 14 wt percent petrographic studies and raman spectroscopy identify three varieties of carbonaceous matter primary syngenetic premetamorphic epigenetic grain coating and postmetamorphic epigenetic uraniferous migrated altered rocks are rarely encountered values of 34 s for sulfides range from 5 to 15 per mil and are interpreted to reflect a combination of inorganic thermochemical reduction of seawater and bacterial activity no specific sulfur isotope patterns for individual minerals can be established indicating nonequilibrium conditions homogeneous lead isotope signatures of galena 206 pb 204 pb 16 20 16 22 207 pb 206 pb 15 48 15 51 208 pb 207 pb 35 86 35 92 suggest that all pb was derived from a single crustal source and paragenetically late crosscutting galena appears to have been remobilized from bedding parallel galena despite the occurrence of uranium in similar rocks nearby uranium is quantitatively insignificant in the browns deposit and is not genetically related to base metal mineralization instead it is linked to brittle deformation in the waning stages of orogenesis the browns deposit differs from other well known sediment hosted stratiform ore deposits both the zambian copperbelt and the polish kupferschiefer deposits are copper dominant and hosted in sedimentary sequences with significant psammitic components the pb zn ag deposits of the proterozoic australian zinc province also have significant carbonate in their host rocks e g carbonaceous dolomitic and siltstone at mcarthur river and lack economically interesting cu co and ni the nearby woodcutters pb zn ag deposit in rocks of similar age also differs in structural setting veins dominant metals and pb isotopes from the browns deposit

seasonal circulation patterns of the yellow and east china seas derived from satellite tracked drifter trajectories and hydrographic observations abstract we investigated seasonal circulation patterns of the yellow and east china seas yecs by reviewing previous works on the circulation and its dominant currents and taking into account newly compiled trajectories of satellite tracked drifters collected between the 1980s and 2000s the circulation patterns suggested before the 1990s can be categorized into two groups depending on the identified origin of the tsushima warm current in the korea tsushima straits i branching from the kuroshio southwest of kyushu or ii northeastward continuation of the taiwan strait throughflow the branching of the kuroshio southwest of kyushu and northeast of taiwan was clearly evidenced by current measurements and concurrent hydrographic surveys however there is still no clear evidence for the northeastward pathway of taiwan strait throughflow across the mid shelf area of the east china sea target oriented surveys in the 1990s and 2000s employing advanced instruments such as drifter tracking and acoustic doppler current profiler measurements now provide decisive proof of the clockwise rounding of the cheju warm current around jeju do throughout the year of the northeastward extension of changjiang discharge in summer and of the presence of the yellow sea warm current only in winter thus both coastal currents in shallow water and secondary branch currents of the kuroshio such as the yellow sea warm current are found to significantly change from winter to summer to better present the basic pattern of yecs circulation and its seasonality we have constructed seasonal circulations patterns based on review results on the newly compiled drifter trajectories and on hydrographic observations further investigations should be carried out in future with support of comprehensive current measurements on shelf areas and through elaborate numerical modeling

an asymmetric upwind flow yellow sea warm current 1 new observations in the western yellow sea 1 the winter water mass along the yellow sea trough yst especially on the western side of the trough is considerably warmer and saltier than the ambient shelf water mass this observed tongue shape hydrographic feature implies the existence of a winter along trough and onshore current often referred to as the yellow sea warm current yswc however the yswc has not been confirmed by direct current measurements and therefore skepticism remains regarding its existence some studies suggest that the presence of the warm water could be due to frontal instability eddies or synoptic scale wind bursts it is noted that in situ observations used in most previous studies were from the central and eastern sides of the yst even though it is known that the warm water core is more pronounced along the western side data from the western side have been scarce here we present a set of newly available chinese observations including some from a coordinated effort involving three chinese vessels in the western yst during the 2006 2007 winter the data show unambiguously the existence of the warm current on the western side of yst both the current and hydrography observations indicate a dominant barotropic structure of yswc the westward deviation of yswc axis is particularly obvious to the south of 35 n and is clearly associated with an onshore movement of warm water to the north of 35 n the yswc flows along the bathymetry with slightly downslope movement we conclude that the barotropic current is mainly responsible for the warm water intrusion while the ekman and baroclinic currents play an important but secondary role these observations help fill an observational gap and establish a more complete view of the yswc

nitrogen isotope evidence for redox variations at the ediacaran cambrian transition in south china abstractnitrogen isotope 15n analyses of the early cambrian ca 542 520 ma strata in the yangtze gorges area south china reveal a prominent positive 15n excursion 8 concurrent with a negative shift in organic carbon isotopes 13corg at the early nemakit daldynian or early fortunian stage this positive 15n excursion in combination with the previously reported paired 13ccarb 13corg at this interval can be interpreted as resulting from denitrification with large isotopic fractionation subsequent 15n from early nemakit daldynian to early tommotian stage 2 are dominated by stable values fluctuating between 2 and 2 close to that of atmosphere n2 0 accompanied by the low and stable 13corg 33 and decoupled 13ccarb 13corg we argue that the relatively low and invariant 15n values from this interval likely resulted from enhanced n fixation with limited isotopic fractionation enhanced n fixation is generally associated with significant nutrient n loss mainly through denit

comparison of wind and tidal contributions to seasonal circulation of the yellow sea 1 seasonal circulation of the yellow sea ys in response to wind and tidal forces is examined using a three dimensional numerical model wind forcing affects the wintertime circulation of the ys on the other hand the summer southerly monsoon is weak and therefore has little impact on the circulation on the basis of comparative experiments with and without wind conditions results indicate that the yellow sea warm current yswc along the ys trough exists regardless of wind forcing however strong winter northerly winds intensify the southward coastal flows along both coasts of the ys and therefore the northward intrusion of the yswc becomes stronger these flows in the ys are substantially weakened when wind forcing is not applied to the model in addition to wind driven circulation tide induced circulation is also dominant in the ys particularly in summer in winter the tidal effect weakens the upwind and downwind flows in response to the strong northerly winds while in summer tidal forcing induces a strong southward residual flow along the western slope and a cyclonic gyre with a bottom cold water dome at the central region of the ys the southward residual current possibly explains the southward movement of the yellow sea bottom cold water as observed in summer comparison to the effects of parameterized tidal mixing suggests that residual flow driven by explicit tidal forcing plays an important role in the summertime circulation of the ys

structure and eastward extension of the changjiang river plume in the east china sea 1 the hydrographic structure and offshore extension of freshwater plume discharged from the changjiang also known as the yangtze river in the northern east china sea were investigated by analyzing conductivity temperature depth ctd data and drifter trajectories collected during the summers of 1997 and 1998 from june to early september when southerly winds prevail the plume tends to move northeast in the chinese coastal area and then separates from the coastal zone to travel eastward over 400 km offshore across the western shelf of the northern east china sea during other seasons when northerly winds prevail the plume is confined to the chinese coast in the summer the plume in the midshelf confined to a thin surface layer 10 to 15 m thick extends eastward in the form of patches of low salinity water rather than spreading as a tongue shaped pattern from the changjiang mouth the eastward movement of patches in the western shelf is primarily due to upwelling favorable southerly winds upon reaching the vicinity of cheju do an island in the middle of northern east china sea the patches are advected to the korea tsushima strait by either the cheju warm current or a northward flowing mean current of the kuroshio branch current and then finally flow into the east japan sea

frontal circulation and westward transversal current at the yellow sea entrance in winter 1 during the wintertime monsoon a tongue shaped thermohaline front is established at the yellow sea ys entrance where the cheju warm current cwc water originating in the kuroshio and the ys cold water meet the frontal circulation as well as the frontal structure has been investigated by analyzing comprehensive conductivity temperature density data float tracks current data and wind data the front develops by the westward advance of the cwc water but it is bounded by the shallow changjiang banks cb that acts like a stopper in the deep part of the ys entrance the northern part of the tongue shaped front displays a wave like motion of 20 km in amplitude and 80 km in wavelength and isotherms isohalines and isopycnals are declined downward toward the north the geostrophic current field indicates formation of a cyclonic circulation along the front which consists of a westward transversal current tc along 34 n and a southeastward outflow along the 50 m isobath of the cb the westward trajectories of floats along the northern front support existence of the tc and a superposition of float tracks evidences cyclonic frontal circulation the new observational findings of the tc and the cyclonic circulation do not match the classical paradigm of a northerly wind driven circulation which consists of the northward inflow through the central trough and the southward outflow on the coastal sides the cyclonic turning of the cold water around the warm tongue stands in contrast with the anticyclonic rounding of the warm cwc water around jeju do

episodic surface intrusions in the yellow sea during relaxation of northerly winds the surface currents over the yellow and east china seas are mapped from the geostationary ocean color imager goci based on a composite of six intrusion events in january april the strong northward surface current in the yellow sea is shown to be concentrated along the deep trough accompanied by a broad northward surface current over the east china sea from the corresponding surface winds the episodic northward surface flow bursts appear to be associated with abrupt changes from the strong northerly winds to weak southerly winds during cold front passages a three dimensional model driven with observed surface winds is used to simulate the observed shelf wide response to northerly winds there is an outstanding agreement between the simulated and observed surface currents the surface intrusion in the yellow sea is shown to be driven primarily by a barotropic longitudinal surface slope while the strong northward current in the east china sea is associated with a coastal trapped wave moreover the surface intrusion is associated with a large volume transport suggesting that the transient intrusions could be important in the northward heat transport the unprecedented capability of goci satellite in providing a regional circulation pattern in conjunction with complementary model simulations could contribute greatly to understanding of the dynamics of the yellow and east china seas

15n 14n variations in cretaceous atlantic sedimentary sequences implication for past changes in marine nitrogen biogeochemistry at two locations in the atlantic ocean dsdp sites 367 and 530 early to middle cretaceous organic carbon rich beds black shales were found to have significantly lower 15n values lower15n 14n ratios than adjacent organic carbon poor beds white limestones or green claystones while these lithologies are of marine origin the black strata in particular have 15n values that are significantly lower than those previously found in the marine sediment record and most contemporary marine nitrogen pools in contrast black organic carbon rich beds at a third site dsdp site 603 contain predominantly terrestrial organic matter and have c and n isotopic compositions similar to organic matter of modern terrestrial origin the recurring15n depletion in the marine derived cretaceous sequences prove that the nitrogen they contain is the end result of an episodic and atypical biogeochemistry existing isotopic and other data indicate that the low15n relative abundance is the consequence of pelagic rather than post depositional processes reduced ocean circulation increased denitrification and hence reduced euphotic zone nitrate availability may have led to cretaceous phytoplankton assemblages that were periodically dominated by n2 fixing blue green algae a possible source of this sediment15n depletion lack of parallel isotopic shifts in cretaceous terrestrially derived nitrogen site 603 argues that the above change in nitrogen cycling during this period did not extend beyond the marine environment

denitrification in marine shales in northeastern colorado parts of the south platte river alluvial aquifer in northeastern colorado are underlain by the pierre shale a marine deposit of late cretaceous age that is 1000 m thick ground water in the aquifer is contaminated with no3 and the shale contains abundant potential electron donors for denitrification in the forms of organic carbon and sulfide minerals nested piezometers were sampled pore water was squeezed from cores of shale and an injection test was conducted to determine if denitrification in the shale was a sink for alluvial no3 and to measure denitrification rates in the shale measured values of no3 n2 nh4 15n no3 15n n2 and 15n nh4 in the alluvial and shale pore water indicated that denitrification in the shale was a sink for alluvial no3 chemical gradients reaction rate constants and hydraulic head data indicated that denitrification in the shale was limited by the slow rate of no3 transport possibly by diffusion into the shale the apparent in situ first order rate constant for denitrification in the shale based on diffusion calculations was of the order of 0 04 0 4 yr 1 whereas the potential rate constant in the shale based on injection tests was of the order of 60 yr 1 chemical data and mass balance calculations indicate that organic carbon was the primary electron donor for denitrification in the shale during the injection test and ferrous iron was a minor electron donor in the process flux calculations for the conditions encountered at the site indicate that denitrification in the shale could remove only a small fraction of the annual agricultural no3 input to the alluvial aquifer however the relatively large potential first order rate constant for denitrification in the shale indicated that the percentage of no3 uptake by the shale could be considerably larger in areas where no3 advection

age source and stratigraphic implications of pb isotope data for conformable sediment hosted base metal deposits in the proterozoic aravalli delhi orogenic belt northwestern india abstract stratiform sediment hosted base metal deposits in the aravalli delhi orogenic belt of northwestern india are hosted by the sediment dominated bhilwara aravalli and delhi sequences of proterozoic age pb isotope data for 36 samples from five ore districts provide useful stratigraphic and approximate age information model pb ages using a newly developed proterozoic model are 1800 ma for the rampura agucha rajpura dariba and saladipura deposits 1700 ma for the zawar deposits and 1100 ma for the ambaji and deri deposits mineralization in this orogenic belt thus occurred at three stages in middle to upper proterozoic times the oldest of these reflected by deposits in the bhilwara sequence was of broad regional extent the rampura agucha deposit is thus hosted by highly metamorphosed rocks that belong to the bhilwara belt and not to an older supracrustal component of the archean banded gneissic complex the host rocks to the saladipura deposit are bhilwara equivalent and are not part of the delhi supergroup as previously mapped and therefore stratigraphic assignments in the area must be re examined model ages of 1100 ma for the ambaji deri deposits are the only evidence obtained in this study regarding the age of the delhi supergroup and are in apparent conflict with much older ages indicated by previous studies rocks of such late upper proterozoic age may be restricted to the southwestern segment of the orogenic belt or alternatively thrust stacking and or interfolding of lithologically similar sequences of a wide range of ages throughout the belt may not yet be evident because of the limited age and isotopic data presently available all the data can be readily explained by the extraction of pb from sediments derived from an upper crustal basement the isotopic compositions of the zawar deposits provide the clearest evidence for an ancient u enriched upper crustal source the ambaji deri pb data suggest a mature status of the delhi are when these deposits were formed

chemostratigraphy and magnetic susceptibility of the late devonian frasnian famennian transition in western canada and southern china implications for carbon and nutrient cycling and mass extinction we investigate the late devonian frasnian famennian extinction interval in western alberta and south china to shed light on the palaeoecological and palaeoceanographic conditions that characterize this biotic crisis both the lower and upper kellwasser events are documented in western canada only the upper kellwasser event has been evaluated in south china our multi proxy geochemical approach reveals that these events are characterized by positive d 13 c and d 15 n excursions and increasing magnetic susceptibility canada china and increases in detrital al si ti zr productivity cu ni zn and redox mo u v elemental proxies canada we interpret these trends as part of a systemic palaeoecological shift associated with the development of wide spread terrestrial forests and their alteration of chemical mechanical weathering patterns increase in detrital proxies is thus interpreted as resulting from pedogenically driven weathering on the con tinents that nutrified epeiric and continental margin seas high biological productivity led to eutro phication and development of suboxic to anoxic conditions during both events and probably euxinic conditions during the upper kellwasser event in western canada positived 13 c excursions are the telltale signature of excessive carbon burial while redox proxies and d 15 n records indicate

yellow and east china seas response to winds and currents the influences of the kuroshio current kuc taiwan warm current twc and surface wind stress on the yellow and east china seas yes are examined using tracers in a princeton ocean model two experiments are performed one with wind stress and one without seasonal variations in the inflow and outflow of the twc and tsushima current are specified to examine the effects of the current transports two separate tracers are inserted into each model experiment to track the pattern of kuc and twc waters into the yes the two main areas of kuc and twc water movement into the yellow sea are the southern entrance to the yellow sea trough and the yangtze relict river valley results indicate that kuc and twc waters advect into the yellow sea regardless of wind stress however in the yellow sea during winter the wind stress increases kuc and twc concentration at 20 m the wind stress also produces short time period events that horizontally advect water masses and spatially smooth seasonally averaged water mass concentrations the bottom ekman layer appears to be one of the mechanisms driving the northward bottom flow across the east china sea shelf the bottom friction layer is stronger in summer when the twc velocity is high the bottom friction layer draws kuc water across the bottom of the continental shelf into the yangtze relict river valley and generates upwelling along the chinese coast

does the yellow sea warm current really exist as a persistent mean flow does saline water of kuroshio origin intrude into the yellow sea interior by a persistent mean current through the yellow sea warm current or by an intermittently generated wind driven current this very fundamental question is discussed by analyzing comprehensive conductivity temperature depth data collected over the entire southern yellow sea basin and by analyzing satellite tracked drifter trajectories collected in 1996 and 1997 in the southwestern yellow sea relatively saline water 33 0 34 0 psu persists year round implying a northwestward intrusion of cheju warm current water cwcw this water is a mixture of saline cwcw with salinity higher than 34 0 psu and fresh yellow sea waters with salinity 33 0 psu during the winter monsoon the mixed water distribution is tongue shaped apparently intruding from the cwcw area at the same time a strong thermohaline front with a horizontal form similar to the greek letter forms across the southern entrance of the central yellow sea trough and separates the mixed water area from the cwcw during the summer monsoon the cwcw intrusion is weak and the mixed water that intruded in the previous winter monsoon remains inside the trough as its salinity decreases in winter occasional collapses of part of the front on the western side of the trough are observed presumably in response to an imbalance between northwest currents generated by strong northerly wind bursts and southeast tide induced residual currents saline water in the frontal zone may then flush into the southwestern yellow sea through the collapsed area of the front we conclude that the yswc is not a persistent mean current we also conclude that cwcw may be transported to the southwestern yellow sea in winter by the intermittently generated northwest currents on the western slope of the trough which override the tide induced residual currents that flow to the southeast in this part of the basin

geocarbsulf a combined model for phanerozoic atmospheric o2 and co2 abstract a model for the combined long term cycles of carbon and sulfur has been constructed which combines all the factors modifying weathering and degassing of the geocarb iii model berner r a kothavala z 2001 geocarb iii a revised model of atmospheric co2 over phanerozoic time am j sci 301 182 204 for co2 with rapid recycling and oxygen dependent carbon and sulfur isotope fractionation of an isotope mass balance model for o2 berner r a 2001 modeling atmospheric o2 over phanerozoic time geochim cosmochim acta 65 685 694 new isotopic data for both carbon and sulfur are used and new feedbacks are created by combining the models sensitivity analysis is done by determining 1 the effect on weathering rates of using rapid recycling rapid recycling treats carbon and sulfur weathering in terms of young rapidly weathering rocks and older more slowly weathering rocks 2 the effect on o2 of using different initial starting conditions 3 the effect on o2 of using different data for carbon isotope fractionation during photosynthesis and alternative values of oceanic 13c for the past 200 million years 4 the effect on sulfur isotope fractionation and on o2 of varying the size of o2 feedback during sedimentary pyrite formation 5 the effect on o2 of varying the dependence of organic matter and pyrite weathering on tectonic uplift plus erosion and the degree of exposure of coastal lands by sea level change 6 the effect on co2 of adding the variability of volcanic rock weathering over time berner r a 2006 inclusion of the weathering of volcanic rocks in the geocarbsulf model am j sci 306 in press results show a similar trend of atmospheric co2 over the phanerozoic to the results of geocarb iii but with some differences during the early paleozoic and for variable volcanic rock weathering lower co2 values during the mesozoic atmospheric oxygen shows a major broad late paleozoic peak with a maximum value of about 30 o2 in the permian a secondary less broad peak centered near the silurian devonian boundary variation between 15 and 20 o2 during the cambrian and ordovician a very sharp drop from 30 to 15 o2 at the permo triassic boundary and a more or less continuous rise in o2 from the late triassic to the present

nitrogen isotope record of fluid rock interactions in the skiddaw aureole and granite english lake district the skiddaw granite and its contact metamorphic aureole in the english lake district provide an excellent opportunity to test the capability of the n isotope system to trace devolatilization and large scale transfer of crustal fluids in the aureole skiddaw group metasedimentary rocks with relatively uniform lithology and major element compositions show a dramatic decrease in n content toward the granite contact from or 800 ppm at distances 2 5 km from the contact to 1 5 km these rocks have extremely uniform delta 15 n air near 3 7 per mil whereas closer to the contact or 1 km delta 15 n is shifted to higher values up to 8 7 per mil the coupled decreases in n content and increases in delta 15 n are compatible with the removal of n having low delta 15 n in fluids during continuous prograde devolatilization reactions involving the break down of white mica and the stabilization of biotite cordierite and andalusite bearing assemblages in the same metasedimentary rocks the lack of obvious trends in major element concentrations including sio 2 tio 2 sio 2 al 2 o 3 and the ratios of other major oxides to tio 2 and al 2 o 3 with distance from the granitic contact is consistent with minimal change in major element composition during the contact metamorphism ratios of whole rock n b rb and ba concentrations to whole rock k 2 o content are believed to reflect the differing fluid mica partitioning and involving varying relative proportions of white mica and biotite of these trace elements during devolatilization reactions greisenized skiddaw granite from a borehole is enriched in n range of 17 225 ppm for whole rocks and white mica separates relative to the unaltered granite whole rock 30 ppm and has delta 15 n of 1 0 to 4 8 per mil the n concentrations and delta 15 n of the wall rocks and greisenized granites combined with c isotopic data carbonate and carbonaceous matter for the same rocks are consistent with the mobilization of fluids having low delta 15 n and delta 13 c pdb values from the devolatilized aureole into the cooling intrusive body such transport is consistent with the predictions of recent theoretical models of late stage hydrothermal evolution in cooling intrusive systems

geochemical and tectonic uplift controls on rock nitrogen inputs across terrestrial ecosystems rock contains 99 of earth s reactive nitrogen n but questions remain over the direct importance of rock n weathering inputs to terrestrial biogeochemical cycling here we investigate the factors that regulate rock n abundance and develop a new model for quantifying rock n mobilization fluxes across desert to temperate rainforest ecosystems in california usa we analyzed the n content of 968 rock samples from 531 locations and compiled 178 cosmogenically derived denudation estimates from across the region to identify landscapes and ecosystems where rocks account for a significant fraction of terrestrial n inputs strong coherence between rock n content and geophysical factors such as protolith i e parent rock grain size and thermal history are observed a spatial model that combines rock geochemistry with lithology and topography demonstrates that average rock n reservoirs range from 0 18 to 1 2 kg n m 3 80 to 534 mg n kg 1 across the nine geomorphic provinces of california and estimates a rock n denudation flux of 20 92 gg yr 1 across the entire study area natural atmospheric inputs 140 gg yr 1 the model highlights regional differences in rock n mobilization and points to the coast ranges transverse ranges and the klamath mountains as regions where rock n could contribute meaningfully to ecosystem n cycling contrasting these data to global compilations suggests that our findings are broadly applicable beyond california and that the n abundance and variability in rock are well constrained across most of the earth system

tongue shaped frontal structure and warm water intrusion in the southern yellow sea in winter 1 in winter a thermohaline front forms at the yellow sea ys entrance where the warm and saline cheju warm current cwc water meets cold coastal water the frontal structure as well as the northwestward intrusion of the warm water was investigated by analyzing conductivity temperature depth ctd data tracks of drifting floats moored current data and satellite images the cwc water advances westward as a tongue with its tip heading westward across the ys entrance not intruding northward along the deepest part of the ys trough whereas a secondary warm water band is developed northwestward along the western flank of the trough floats in the warm tongue moved northwestward across the western frontal zone where the frontal structure was weak reflecting the northwestward intrusion along the 50 70 m isobaths through the frontal zone currents in the trough do not always meet the upwind flow theory that in an elongated basin the wind driven flow is upwind in the deep channel but rather show the predominance of the southward downwind flow model experiments show that on the western flank of the trough both the southeastward tide induced residual flow and the southeastward flow due to the nonlinear effect between tide and wind are generated at the same time thus the intermittent intrusion of the cwc across the western frontal zone may be closely associated with the predominance of the upwind flow over the southeastward nonlinear interacted flow

effects of the yellow sea warm current on the winter temperature distribution in a numerical model 1 the temperature distribution and circulation patterns in the yellow sea ys are examined by using a wave tide circulation coupled numerical model this model sufficiently reproduces the variation of the warm tongue structure of the yellow sea warm current yswc from the double branches flowing along the ys trough and the western 60 m isobath in january to the single stream along the western temperature front in march this is observed in both the long term monthly climatology and the satellite based sea surface temperature images in recent years examining the local heat balance in the numerical model during the entire cooling period it is found that the yswc has a very important influence on the ys warm tongue structure compared with the surface cooling the influence of the advection is small in the coastal shallow area but large in the deep warm tongue area up to 50 of the magnitude of heat flux although bathymetry is the essential factor which causes the temperature front the yswc is the key factor which positions shapes and maintains the warm tongue structure this helps to affirm the existence of the yswc at least as a monthly mean flow however more high resolution current observations in deeper layers west of cheju island and the western fork of the ys trough are needed to confirm the existence of the yswc and its characteristic timescale in the real ys

modeling atmospheric o2 over phanerozoic time a carbon and sulfur isotope mass balance model has been constructed for calculating the variation of atmospheric o2 over phanerozoic time in order to obtain realistic o2 levels rapid sediment recycling and o2 dependent isotope fractionation have been employed by the modelling the dependence of isotope fractionation on o2 is based for carbon on the results of laboratory photosynthesis experiments and for sulfur on the observed relation between oxidation reduction recycling and s isotope fractionation during early diagenetic pyrite formation the range of fractionations used in the modeling agree with measurements of phanerozoic sediments by others results derived from extensive sensitivity analysis suggest that there was a positive excursion of o2 to levels as high as 35 during the permo carboniferous high o2 at this time agrees with independent modeling based on the abundances of organic matter and pyrite in sediments and with the occurrence of giant insects during this period the cause of the excursion is believed to be the rise of vascular land plants and the consequent increased production of o2 by the burial in sediments of lignin rich organic matter that was resistant to biological decomposition