inductively mapping expert derived soil landscape units within dambo wetland catenae using multispectral and topographic data abstract constructing a cost effective and detailed digital soil map of africa will require the extensive utilization of both legacy soil data and legacy soil landscape knowledge which in africa is primarily available from reconnaissance scale catena or association maps and related studies we evaluated a hybrid approach for disaggregating reconnaissance scale soil maps rapid and inexpensive delineation of representative soil landscape units in the field using expert knowledge followed by the use of inductive empirical and correlative modeling techniques to map these landscape units our 2214 km 2 study area located in central uganda consisted predominantly of catenae that terminate in seasonal valley floor wetlands called dambos a type of landscape that can be found throughout the african continent for model training and validation we identified four landscape classes in the field using published expert knowledge well drained uplands red soils sloping dambo wetland margins gradient 2 frequently inundated dambo bottoms hummocky microtopography and flat dambo floors default using binary decision trees bdt with multispectral and topographic remote sensing covariates we created a 20 m resolution map of these four classes multispectral inputs included reflectance values vegetation indices and spectral mixture modeling fractions from systeme pour l observacion de la terre spot 4 satellite images acquired in december 2006 and february 2007 topographic inputs consisted of a digital elevation model dem from shuttle radar topography mission srtm data slope and 20 relative elevation layers calculated using moving windows of various sizes decision rules were based upon the following input variables the normalized difference vegetation index ndvi the normalized difference infrared index ndii the shortwave infrared swir reflectance northing slope and two relative elevation layers the overall classification accuracy of 75 5 and kappa coefficient of 0 67 suggest that a combination of multispectral topographic and spatial data may be used to reliably classify landscape classes for dambo terminated catenae at 59 of the 2214 km 2 study area the upland class was by far the most abundant with margins at 21 floors at 12 and bottoms at 8 a statistical analysis of soil property data from a small catchment located within the study area showed significant class differences in soil texture color organic carbon soc base saturation ph effective cation exchange capacity ecec and clay mineralogy though detailed soil maps are rare in africa reconnaissance soil maps can be inexpensively disaggregated to provide a valuable starting point for digital soil mapping

flow structure and transport in the yucatan channel 1 the direct ocean current observations across the yucatan channel collected during the canek program allow the best description to date of the exchange between the caribbean sea and the gulf of mexico a net transport of 23 8 1 sv 1 sv 106m3s 1 95 confidence interval flowed through the yucatan channel from the caribbean sea into the gulf of mexico during the period between september 1999 and june 2000 this is about 20 percent less than the 30 sv accepted as the nominal transport of the florida current and less also than the 28 sv assumed for yucatan in closing the transport budgets for caribbean passages the discrepancy may be an imbalance due to fluctuations in the transports through other passages of the system especially the old bahama and northwest providence channels which remain poorly known our data corroborate the principal features of the flow through the yucatan channel the northerly surface yucatan current and its southerly under current off mexico and the southerly surface cuban counter current near cuba but previously unobserved mean currents are found to exist at depth especially on the eastern side of the channel fluctuations seen in the deep flows are related to volume anomalies over the gulf of mexico a transport through the yucatan channel smaller than previously thought has significant implications for the dynamics of the gulf of mexico and its modeling since this transport is the principal forcing of its circulation the circulation budgets in the western subtropical atlantic should be revised considering these new results

understanding the utility of aerial gamma radiometrics for mapping soil properties through proximal gamma surveys abstract historical aerial gamma radiometrics have been proposed to be an important covariate for characterizing soil properties because it provides information about soil parent material pre existing aerial gamma radiometrics within the united states however can exhibit coarse spatial resolutions and therefore may be unhelpful for soil mapping studies therefore the objective of this work was to test the hypothesis that aerial gamma radiometrics can reliably map soil properties the hypothesis was tested using proximal radiometrics and soil sampling proximal or ground surveys were conducted within four different heterogeneous landscapes and 112 soil samples were collected and characterized for texture i e particle size fractions and or calcium carbonate equivalent proximal and soil relationships were assessed in terms of significance using pearson correlation coefficient testing and stepwise backwards linear regression proximal data were then weighted and averaged within the aerial sensor field of view and subsequently tested for significance with historical aerial data using pearson correlation tests proximal and aerial sensors were then compared in their ability to predict nearby measurements of clay and sand content relationships between texture and proximal gamma measurements were significant p

chronology of warm core ring 82b a chronology constructed from satellite derived thermal imagery is presented to describe the formation and life history of warm core ring 82b this overview provides insight into a classification of features and discrete events associated with gulf stream warm core rings and allows these events as well as our limited shipboard observations to be placed in a broader spatial and temporal context than would otherwise be possible without the satellite data events influencing the evolution of 82b include environmental factors such as meteorological influences and gulf stream interactions as well as those stimulated by encounters with changes in bottom topography the interactions of the ring with surrounding waters are especially noteworthy and the existence of vortex vortex interactions is shown to be a significant cause of local water advection through streamer activity ring events are documented by following changes in ring size shape translation and surface thermal structure our satellite observations are supported by extensive contemporaneous shipboard observations including xbt ctd bops biooptical profiling system temperature profiles and along track sea surface temperature measurements in addition acoustic velocity profiling and drifter trajectories have been used to corroborate hydrographic features of the ring and environs these ship and satellite data form a coherent space time overview of the ring and its environment and show them to be closely related and continually interacting

a tin mineralized topaz rhyolite dike with coeval topaz granite enclaves at qiguling in the qitianling tin district southern china abstract the qiguling topaz rhyolite is present as a dike within the qitianling biotite granite batholith of the nanling range of southern china here the rhyolitic dike 4 5 m wide and 500 m long contains enclaves of topaz granite these rhyolites contain up to 72 wt sio 2 have alumina saturation index asi 1 1 and have groundmasses with estimated fluorine contents of approximately 1 5 wt textural relationships provide evidence of a quenched silicate melt that contains quartz k feldspar albite and zinnwaldite phenocrysts in a groundmass containing abundant topaz the rhyolites in the study area are also strongly enriched in tin 90 2700 ppm and generally have a close association between cassiterite and zinnwaldite although cassiterite is also present as sponge textured fills between rock forming minerals granite enclaves and their hosted rhyolite have similar major geochemical compositions and mineralogies to each other zircon u pb dating indicates that the topaz rhyolite 147 150 ma and topaz granite enclaves 154 ma were formed contemporaneously with ages that overlap within analytical uncertainty in addition the major and trace element compositions of the rhyolite and their granite enclaves are dissimilar to those of the hosting qitianling biotite granite this discovery of granite enclaves within rhyolite dikes suggests the presence of a topaz bearing granite body at depth that may host tin mineralization the expected hidden tin granite may be of great interest in the further exploration

anticyclonic rings in the gulf of mexico abstract using the historical data set this study describes the anticyclonic rings that separated from the loop current in the eastern gulf of mexico six quasi synoptic data sets are used to describe the evolving circulation of the gulf of mexico from october 1966 to september 1967 showing the separation and movement into the western gulf of three anticyclonic rings the historical data are used to determine that these rings typically translate to the west at a mean speed of 2 1 km day 1 their length scale as defined by their rms radii is 183 km an estimate of ring life span as defined by an e folding time is one year within the context of the gulf s water property distributions these rings appear as warm salty bodies the heat and salt added by one of these rings after separation are estimated to be 7 109 j m 2 and 17 g cm 2 respectively the heat and salt added by one of these features play an important role in the heat and salt budget of the western gulf the latter indicates that about one r

apatite chemical composition determined by electron microprobe and laser ablation inductively coupled plasma mass spectrometry as a probe into granite petrogenesis abstract major minor and trace element abundances in apatites from various i and s type igneous and sedimentary granites of the lachlan fold belt have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometer the results show that apatite can accommodate many minor and trace elements whose concentrations and ratios are relatively sensitive to factors controlling many of the fundamental differences between i and s type granites apatites from s type granites generally have higher f but lower cl contents than those from i type granites which is ascribed mainly to the loss of cl during the weathering processes forming the source rocks of s type granites although fractional crystallisation can cause significant enrichment in f as well high mn and fe contents in apatites from s type granites and high s and as abundances in apatites from mafic i type granites result from different oxygen fugacities and degrees of al saturation or aluminosity between metaluminous mafic i type magmas and peraluminous s type and felsic i type magmas there are systematic and distinctive differences in absolute rare earth element ree abundances ree distribution patterns and element ratios e g la y sm nd etc between apatites from different types of granite the strong eu depletion that characterises apatites from s and felsic i type granites is interpreted here to be a result of the uniqueness of crystal chemistry of apatite and high eu2 eu3 ratios in s type and felsic i type magmas which are more reduced and peraluminous than mafic i type magmas strong ree la to eu and th enrichment in apatites from mafic i type granites and marked nd depletion in apatites from most s type and felsic i type granites are caused by the precipitation and fractionation of monazite in the parental magmas of the latter rocks substitution mechanisms are responsible for high na in apatites from s type and felsic i type granites and for high si in apatites from mafic i type granites and may also have important effects on ree partitioning between apatite and melt thus apatite chemistry can be used as an excellent indicator of granite petrogenesis the results have important implications for identifying different types of granite and are potentially significant for determining the provenance of sedimentary rocks

deep flows in the yucatan channel and their relation to changes in the loop current extension 1 the first attempt to establish a relation between the loop current extension and deep flows in yucatan channel was made by maul et al 1985 it was unsuccessful probably because of the low spatial resolution of their observations from september 8 1999 to june 17 2000 eight moorings with acoustic doppler current profilers current meters and thermometers were deployed across the yucatan channel the data from these arrays were used to compute time series of the transports below the level of the deepest isotherm observed in the florida straits as required by a simple box model that restricts deep exchanges with the gulf of mexico to the yucatan channel the surface extension of the loop current was inferred from 3 day advanced very high resolution radiometer imagery from october to may when temperature gradients were sufficient to map the warm water unambiguously the deep transports appear at first unrelated to the rate of change of the loop current extension but filtering the series with a 20 day running mean increases the correlation between the low pass series to 0 62 and up to 0 83 with a lag of 8 5 days with loop current changes leading the deep flows the cumulative deep transport a quantity that favors lower frequencies is very well related correlations 0 9 to the surface extension of the loop current also with a lag of about a week these lags are not statistically significant but suggest a timescale for internal adjustment processes in the gulf of mexico the empirical orthogonal function of the current best related to the area extension of the loop current represents a unidirectional flow across the entire deep section flowing either toward or from the gulf of mexico and includes a strong expression of the yucatan undercurrent

gahnite chrysoberyl and beryl co occurrence as accessory minerals in a highly evolved peraluminous pluton the belvis de monroy leucogranite caceres spain abstract gahnite znal 2 o 4 chrysoberyl beal 2 o 4 and beryl be 3 al 2 si 6 o 18 have been found as accessory minerals in the external highly fractionated leucogranitic unit within the hercynian reversely zoned belvis de monroy pluton westernmost part of the montes de toledo batholith caceres spain the highly felsic sio 2 72 wt and peraluminous acnk 1 2 character of this leucogranite together with the high content of some incompatible elements f li b and p seems to be a primary consequence of fractional crystallization in a magmatic closed system the high be contents and zn fe total ratio 0 01 are relevant factors which have favoured the precipitation of these minerals moreover the si al p b and f activities might be high favouring the magmatic crystallization of such exotic mineral phases together with be rich cordierite f rich micas sillimanite and al rich phosphates in fact the interplay between the silica and alumina activities likely controls the stabilization and the preferential crystallization of gahnite chrysoberyl or beryl chrysoberyl assemblages in mm sized microdomains the p t crystallization conditions are constrained by the muscovite and sillimanite stability fields and the minimum granite al 2 o 3 saturated solidus and have been estimated at temperatures between 670 and 700 c and pressures between 1 and 2 kbar

an exercise in forecasting loop current and eddy frontal positions in the gulf of mexico 1 as part of a model evaluation exercise to forecast loop current and loop current eddy frontal positions in the gulf of mexico the princeton regional ocean forecast system profs is tested to forecast 14 4 week periods aug 25 99 sep 20 00 during which a powerful eddy eddy juggernaut eddy j separated from the loop current and propagated southwestward to initialize each forecast profs assimilates satellite sea surface height ssh anomaly and temperature sst by projecting them into subsurface density using a surface subsurface correlation that is a function of the satellite ssh anomaly the closest distances of the forecast fronts from seven fixed stations in the northern gulf over a 4 week forecast horizon are then compared against frontal observations derived primarily from drifters model forecasts beat persistence and the major source of error is found to be due to the initial hindcast fields

geochronological and geochemical constraints on the petrogenesis of the early paleoproterozoic potassic granite in the lushan area southern margin of the north china craton abstract we conducted a geochronological and geochemical study on the paleoproterozoic potassic granites in the lushan area southern margin of the north china craton ncc to understand the tectonic regime of the ncc at 2 2 2 1 ga this rock suite formed at 2194 29 ma the rocks are rich in sio2 76 10 77 73 wt and k2o 5 94 6 90 wt with high k2o na2o contents from 7 56 wt to 8 48 wt but poor in cao 0 10 0 28 wt p2o5 0 02 0 05 wt and mgo 0 01 0 30 wt mg 1 08 27 3 indicating they experienced fractional crystallization major element compositions suggest the potassic granites share an affinity with high k calc alkaline granite even though the lushan potassic granitic rocks have high a cnk ratios 1 11 1 25 which can reach peraluminous feature the very low p2o5 contents and negative correlation of p2o5 and sio2 ruling out they are s type granites different from peralkaline a type granites the lushan potassic granites have variable zr concentrations 160 344 ppm 226 ppm on average and 10 000 ga al ratios 1 76 3 00 together with high zircon saturation temperatures tzr 826 885 c indicating they are fractionated aluminous a type granites enriched lree la yb n 9 72 81 8 negative eu anomalies and low sr y with no correlations in sr y and sr zr versus cao suggest the possible presence of ca rich plagioclase and absence of garnet in the residual magmatic zircon grains have variable ehf t values 2 4 to 7 3 with zircon two stage hf model ages tdmc varying from 2848 ma to 2306 ma mostly around ca 2 5 ga and are plotted in the evolution line of crustal felsic rock we propose that the rocks mainly formed by partial melting of ca 2 50 ga tonalitic granodioritic crust as a result of upwelling mantle derived magmas which provided thermal flux and source materials in an intra continent rifting the ca 2 2 ga magmatism suggests that intra continental rifting occurred at 2 35 1 97 ga at least in the southern margin of the ncc after its final cratonization in the late neoarchean

a multiresolution index of valley bottom flatness for mapping depositional areas 1 valley bottoms function as hydrological buffers that significantly affect runoff behavior distinguishing valley bottoms from hillslopes is an important first step in identifying and characterizing sediment deposits for hydrologic and geomorphic purposes valley bottoms occur at a range of scales from a few meters to hundreds of kilometers in extent this paper describes an algorithm for using digital elevation models to identify valley bottoms based on their topographic signature as flat low lying areas the algorithm operates at a range of scales and combines the results at different scales into a single multiresolution index this index classifies degrees of valley bottom flatness which may be related to depth of deposit the index can also be used to identify groundwater constrictions and to delineate hydrologic and geomorphic units

motion and evolution of oceanic rings in a numerical model and in observations observed properties of oceanic rings are compared to rings produced in a two gyre wind driven numerical ocean model and in a model of the south atlantic indian ocean their temporal evolution is discussed in terms of structure and translation rate they exhibit substantial similarity in terms of thermocline depth ring size swirl velocities and translations speeds in both observations and numerical model results the propagation speeds are 2 to 5 times faster than that of an equivalent isolated eddy which is of the order of the long rossby wave speed this is attributed to advection by the mean flows furthermore it is observed that the model rings have a coherent structure all the way to the bottom there is strong evidence that this is also the case in real oceanic rings one major difference between observed and modeled rings is in their decay rate the temporal decay of the rings in the models and observations is therefore discussed in relation to the decay mechanisms at work and the frictional parameterization of the model

impact of a warm ocean eddy s circulation on hurricane induced sea surface cooling with implications for hurricane intensity abstractupper oceanic heat content ohc in advance of a hurricane is generally superior to prestorm sea surface temperature sst for indicating favorable regions for hurricane intensification and maintenance ohc is important because a hurricane s surface winds mix the upper ocean and entrain cooler water into the oceanic mixed layer from below subsequently cooling the sea surface in the region providing heat energy to the storm for a given initial sst increased ohc typically decreases the wind induced sea surface cooling and a warm ocean eddy wcr has a higher ohc than its surroundings so conditions typically become more favorable for a hurricane to intensify when the storm s core encounters a wcr when considering hurricane intensity however one often neglected aspect of a wcr is its anticyclonic circulation this circulation may impact the location and magnitude of the hurricane induced sea surface cooling using an ocean model either prescribed hurricane wind stress or wind stress obtained

estimating abundances of volatile and other mobile components in evolved silicic melts through mineral melt equilibria to variable degrees of accuracy from source partitioning between and earths residual minerals and anatectic melts through melt fractionation partitioning between igneous minerals and residual melts to the end stages of magma solidification where higher concentrations of normally trace elements may promote saturation in their crystalline phases the magmatic abundance of rare alkalis and alkaline earths

h2o diffusion in peralkaline to peraluminous rhyolitic melts the diffusion of water in a peralkaline and a peraluminous rhyolitic melt was investigated at temperatures of 714 1 493 k and pressures of 100 and 500 mpa at temperatures below 923 k dehydration experiments were performed on glasses containing about 2 wt h2ot in cold seal pressure vessels at high temperatures diffusion couples of water poor 0 5 wt h2ot and water rich 2 wt h2ot melts were run in an internally heated gas pressure vessel argon was the pressure medium in both cases concentration profiles of hydrous species oh groups and h2o molecules were measured along the diffusion direction using near infrared nir microspectroscopy the bulk water diffusivity d text h 2 text o t was derived from profiles of total water c text h 2 text o t using a modified boltzmann matano method as well as using fittings assuming a functional relationship between d text h 2 text o t and c text h 2 text o t both methods consistently indicate that d text h 2 text o t is proportional to c text h 2 text o t in this range of water contents for both bulk compositions in agreement with previous work on metaluminous rhyolite the water diffusivity in the peraluminous melts agrees very well with data for metaluminous rhyolites implying that an excess of al2o3 with respect to alkalis does not affect water diffusion on the other hand water diffusion is faster by roughly a factor of two in the peralkaline melt compared to the metaluminous melt the following expression for the water diffusivity in the peralkaline rhyolite as a function of temperature and pressure was obtained by least squares fitting log d text h 2 text o t 1 text wt 7 09 pm 0 15 frac 4 788 pm 166 0 56 pm 0 21 times p t where d text h 2 text o t 1 text wt is the water diffusivity at 1 wt h2ot in m2 s t is the temperature in k and p is the pressure in mpa the above equation reproduces the experimental data 14 runs in total with a standard fit error of 0 15 log units it can be employed to model degassing of peralkaline melts at water contents up to 2 wt

gulf stream transport and mixing processes via coherent structure dynamics the gulf stream has been characterized as either a barrier or blender to fluid transfer a duality relevant to gyre scale climate adjustment however previous characterization depended on relatively sparse lagrangian in situ observations the finite time lyapunov exponent ftle is calculated from satellite altimetry to identify lagrangian coherent structures lcs in the gulf stream region these lcs provide dense sampling of flow and capture distinct regions associated with mixing independent observations of ocean color contain similar flow dependent structures providing verification of the method and highlighting transport and mixing processes that influence sea surface temperature and chlorophyll among other water properties diagnosed lcs support the existing bower kinematic model of the gulf stream but also highlight novel behavior of comparable importance these include vortex pinch off and formation of spiral eddies clearly identified by lcs and which may be explained by considering changes to flow topology and the dynamics of shear flow instability at both small and large rossby number such processes seen though lcs may further enable validation of climate models the spatial distribution of these intermittent processes is characterized in terms of the criticality of jet dynamics with respect to rossby wave propagation and whether the jet is in an unstable or wave maker regime the generation and connectivity of hyperbolic trajectories in the flow appears to play an important role in governing large scale transport and mixing across the gulf stream

hydrography of the gulf of mexico using autonomous floats abstractfourteen autonomous profiling floats equipped with ctds were deployed in the deep eastern and western basins of the gulf of mexico over a four year interval july 2011 august 2015 produ

disaggregating and harmonising soil map units through resampled classification trees abstract legacy soil maps typically consist of a tessellation of polygon soil map unit delineations where the map units consist of a defined assemblage of soil classes assumed to exist in more or less fixed proportions there are several limitations in this kind of mapping approach that relate to the original intent of the soil survey the effect of mapping scale and the nature of soil polygon boundaries yet perhaps a more fundamental limitation is the fact that most of the time the soil classes that comprise the soil map units are not mapped individually in effect their spatial distributions are unknown beyond the qualitative indications given in the accompanying soil map unit report spatial disaggregation of soil map units attempts to map the spatial distribution of the individual soil classes that comprise a legacy soil map we developed an approach called disaggregation and harmonisation of soil map units through resampled classification trees dsmart dsmart samples the polygons of a legacy soil map and uses classification trees to generate a number of realisations of the potential soil class distribution the realisations are then used to estimate the probability of occurrence of the individual soil classes these estimates are mapped as raster grids which can overcome some of the limitations of mapping scale and polygon boundaries inherent in the original legacy soil map we demonstrate the dsmart approach on a legacy soil map from the former dalrymple shire in central queensland australia we mapped the estimated probability of occurrence of the 71 soil classes in the legacy soil map as well as the most probable soil class second most probable soil class and the degree of confusion between them as determined by a confusion index validation on 285 observed soil profiles indicated that for 48 4 of the validation profiles the observed soil class was identified in the top three most probable soil classes

spatial structure of anticyclonic eddies in the algerian basin mediterranean sea analyzed using the okubo weiss parameter abstract three algerian eddies open sea big anticyclonic eddies in the algerian basin western mediterranean sea are studied in detail using altimetric and in situ data to characterize their spatial structure we make use of the okubo weiss parameter which allows to separate the flow into vorticity dominated and deformation dominated regions the application of this parameter to geostrophic velocity fields obtained from sea level anomaly maps show that the observed eddies have a spatial structure in close resemblance to that found in coherent vortices of two dimensional turbulence these eddies appear to have a rather coherent vorticity dominated core region surrounded by an outer region dominated by deformation with a very complicated and variable in time structure this analysis is also applied to ctd data collected across three eddies sampled between 1997 and 1998 from these data eddy cores are equivalently defined as the interior region enclosed by the maximum of azimuthal velocity and are consistent with the horizontal structures seen in sla maps the distinction between the core and the outer region circulation cell is particularly important to understand the role of transport and stirring of properties associated to eddies as illustrated by the observed salinity structure some selected sst images and drifter trajectories the core is characterized by very small isopycnal salinity gradients while the surrounding cell is characterized by a strong slope of isohalines with respect to isopycnals persistent stagnation points are observed around the eddy and correspond to regions of high values of deformation with respect to vorticity these regions allow analyzing characteristic patterns seen in the corresponding sst images in addition drifters trajectories exhibit very different behavior when crossing such regions

incongruent dissolution of ree and sr rich apatite in peraluminous granitic liquids differential apatite monazite and xenotime solubilities during anatexis the relative solubilities of monazite mnz xenotime xno and apatite ap ree and sr rich and ree and sr poor have been studied in peraluminous granitic liquids in month long experiments at 750 c and 200 mpa ph20 in contrast with the high solubility of the apatite 0 7 wtojop205 in strongly peraluminous liquids monazite and xenotime have much lower solubilities 0 05 wt jop205 in mildly to strongly peraluminous compositions p205 in the liquid is 0 03 0 04 wt joat xenotime saturation and 0 02 0 05 wt jo at monazite saturation in keeping with the low p in the glasses re203 contents are below emp detection thresholds 50 08 wt jo for all conditions of experiments saturation of liquid at equilibrium and local saturation around apatite apatite dissolves incongruently crystallizing ree rich monazite on its surface 1 4 m iong grains resulting in similar low ree contents in liquids monazite precipitation occurs along the margins of dissolving apatite crystals even though the bulk liquid is not monazite saturated the abundance of monazite microcrystals increases with the ree content of the apatite and the degree of apatite dissolution the reaction relationship ap liqi mnz liq2 stemming from differences in relative solubilities greater than an order of magnitude between apatite and monazite results in the dissolution of much smaller amounts of ree into peraluminous liquids than expected by simple evaluation of apatite ree contents the amount of ree contributed from apatite directly to peraluminous granitic liquid is related to the amount of apatite dissolved by simple mass balance only if the total ree content of the apatite is sufficiently low that monazite saturation in liquid 50 100 ppm re203 at 750 c is avoided during dissolution of sr rich apatite the sr partitions into the liquid and at 750 c and 200 mpa ph20 the diffusion coefficient of sr in liquid is 2 x 10 10 cm2js r2 0 659 the reaction relationships described above may have application to some textural features observed in natural igneous rocks for example clusters of monazite microcrystals might be indicators of dissolved apatite monazite morphology can be used to distinguish the source of its ree and the general petrological process rock anatexis or magma crystallization under which the monazite formed in addition monazite microcrystals could serve as nucleation sites for other minerals which might explain their common inclusion in biotite and amphibole within granitoids

mixing of a tracer in the pycnocline a patch of sulfur hexafluoride was released in may 1992 in the eastern north atlantic on an isopycnal surface near 300 m depth and was surveyed over a period of 30 months as it dispersed across and along isopycnal surfaces the diapycnal eddy diffusivity k estimated for the first 6 months was 0 12 0 02 cm2 s while for the subsequent 24 months it was 0 17 0 02 cm2 s the vertical tracer distribution remained very close to gaussian for the full 30 months as the root mean square rms dispersion grew from 5 to 50 m lateral dispersion was measured on several scales the growth of the rms width of the tracer streaks from less than 100 m to approximately 300 m within 2 weeks implies an isopycnal diffusivity of 0 07 m2 s at scales of 0 1 to 1 km larger than expected from the interaction between vertical shear of the internal waves and diapycnal mixing teasing of the overall patch initially about 25 km across into streaks with an overall length of 1800 km within 6 months supports predictions of exponential growth by the mesoscale strain field at a rate of 3 0 5 10 7 s 1 the rms width of these streaks estimated as 3 km and maintained in the face of the streak growth indicates an isopycnal diffusivity of 2 m2 s at scales of 1 to 10 km much greater than expected from internal wave shear dispersion the patch was painted in albeit streakily by 12 months confirming expectations from analytical and numerical models homogenization of the patch continued during the subsequent 18 months while the patch continued to spread with an effective isopycnal eddy diffusivity on the order of 1000 m2 s acting at scales of 30 to 300 km

rare earth elements as reactive tracers of biogeochemical weathering in forested rhyolitic terrain article rareearthelements rees were evaluatedaspotentialtracers of biogeochemicalweathering atpedon hillslope and catchment scales in the jemez river basin critical zone observatory jrb czo valles caldera national pre serve nm usa we investigated time series of ree patterns in precipitation soil pore water groundwater and stream water and related these data to ree composition of soil rock and atmospheric dust ree signatures in stream waters are dynamic reflecting processes that occur along hydrologic flowpaths during transport to the stream including organic matter complexation primary and secondary mineral weathering water soil bedrock interaction and atmospheric deposition strong compositional similarities for the ree between soil waters and stream waters during the initial snowmelt are consistent with shallow subsurface flows to streams most bio

alkali feldspars as a main phosphorus reservoirs in rare metal granites three examples from the bohemian massif czech republic phosphorus rich alkali feldspars were found in three peraluminous highly differentiated albite topaz li mica granites in the w and s parts of the bohemian massif the average contents of p2o5 in k feldspars k i ovy kamen 0 57 wt homolka 0 77 wt and podlesi 0 83 wt are higher than the average contents of p2o5 in albites k i ovy kamen 0 23 wt homolka 0 23 wt and podlesi 0 39 wt the analyses of feldspars indicate that partition coefficient of phosphorus between k feldspar and albite range from 1 5 to 2 5 measured data in k feldspars suggest a statistically significant difference from the al3 p5 2 si4 substitution mechanism for higher phosphorus concentration the p content in k feldspars from the podlesi granite represent the highest p content in natural feldspar known to date up to 2 5 wt of p2o5 it is suggested that all studied granites retained nearly all phosphorus of granitic melts and that their alkali feldspars represent major reservoirs of phosphorus

wintertime convection in a gulf stream warm core ring abstract wintertime convection creates deep mixed layers which determine the water mass characteristics and potential vorticity for waters in the main pycnocline of the world ocean diabatic cooling is most intense in the northern hemisphere near the northwestern boundary of subtropical gyres where outbreaks of cold dry continental air over warm surfaces waters produce large sensible and latent heat losses from the ocean gulf stream warm core rings containing warm salty sargasso sea water are cast off to the north of the gulf stream in close proximity to the northeastern coast of north america we have observed the convective cooling of one these rings 821 during january 1982 from the usns bartlett during one cold air outbreak we calculate a net surface hear loss from the ring to the atmosphere of 800 w m 2 and a deepening of the surface mixed layer form 50 to 190 m the heat budget for the ring required a lateral heat exchange with the surrounding slope water in order to achieve a balanced heat bu

mesoscale eddies off peru in altimeter records identification algorithms and eddy spatio temporal patterns relatively little is known about coherent vortices in the eastern south pacific along the peruvian coast even with regard to basic facts about their frequency of occurrence longevity and structure this study addresses these issues with nearly 15 years of relatively high resolution satellite altimetry measurements we first compare two distinct automated methods for eddy identification the objective validation protocol shows that the rarely used geometrical or winding angle method based on the curvature of the streamline functions is more accurate than the commonly used okubo weiss algorithm which defines a vortex as a simple connected region with values of okubo weiss parameter weaker than a given threshold we then investigate vortices off peru using more than 20 000 mesoscale eddies identified by the winding angle method coherent eddies characterized by a high ratio of vorticity to deformation rate are typically formed along the coast and propagate westward at 3 6 cm s 1 the vortices have a mean radius of 80 km increasing northward and are most frequently observed off of chimbote 9s and south of san juan 15s the mean eddy lifetime is about 1 month but if eddies survive at least 2 months the probability for surviving an additional week or month is constant at 90 or 67 anticyclonic eddies tend to propagate northwestward whereas cyclonic vortices migrate southwestward in general cyclones and anticyclones are similar except for eddies surviving at least 6 months in this case after a similar 3 4 months of radius and amplitude growth amplitudes or sizes decay particularly rapidly for anticyclonic or cyclonic eddies in terms of intensity cyclonic eddies show a rapid decay during the first 3 months before arriving at a quasi constant value whereas anticyclones exhibit steady decline finally eddy temporal variations were examined at seasonal and interannual scales in the coastal region favorable to the formation of energetic mesoscale structures on seasonal scales eddy activity is maximal in fall and minimum in spring at interannual scales the eddy activity index was maximal during the strong el nino of 1997 1998 but another strong maximum of eddy activity also occurred late in 2004 these temporal variations are probably associated with the intensification of the upwelling thermal front and with the passage of coastal trapped waves which generate baroclinic instabilities further investigation of the mechanisms involved on the eddy genesis is needed

phosphorus in s type magmas the p2o5 content of feldspars from peraluminous granites pegmatites and rhyolites

effect of mesoscale eddies on subtropical mode water variability from the kuroshio extension system study kess abstract forty eight profiling floats have been deployed in the kuroshio extension ke region since may 2004 as part of the kuroshio extension system study kess project by combining the float temperature salinity measurements with satellite altimetry data this study investigates the role played by mesoscale eddies in controlling the property changes in north pacific subtropical mode water stmw following a 3 yr period of low eddy activity in 2002 04 the ke showed a transition to a high eddy kinetic energy state in 2005 this transition is the result of delayed oceanic response to the 2002 shift in the basin scale surface wind forcing in connection with the pacific decadal oscillation the high eddy kinetic energy state of the ke is characterized by successive shedding of strong cold core rings into the recirculation gyre resulting from the interaction of the ke jet with the shatsky rise or the preexisting cutoff rings by transporting northern origin high potential vorticity pv ke water into t

velocity and hydrographic structure of two gulf of mexico warm core rings results from an extensive survey of two gulf of mexico warm core rings are presented the data were taken during a 1 week period in december 1983 using a shipboard acoustic doppler current profiler adcp expendable current probes xcp expendable bathythermographs xbt and a ctd two rings were observed an older one in the western gulf adjacent to the west texas shelf and one just separated from the loop current the western ring was of order 200 km in diameter with peak currents of 1 m s 1 at the 100 m level water properties were uniform and characteristic of the high salinity caribbean subtropical underwater the eastern ring was of order 300 km in diameter with peak currents of near 2 m s 1 at the 100 m level water below 200 m is of caribbean origin while the surface waters show more variability suggesting some inflow of gulf of mexico common water the evolution of the rings is also described based on the cruise measurements satellite avhrr and other observations of opportunity

source controlled 87sr 86sr isotope variability in granitic magmas the inevitable consequence of mineral scale isotopic disequilibrium in the protolith abstract the broad sr isotopic variability exhibited by granitoid rocks is commonly interpreted to reflect the mixing of magmas from different sources however evidence from granites and migmatites indicates that melting and magma extraction from crustal sources can occur sufficiently rapidly that trace element and isotopic equilibration between liquid and residual phases is commonly not achieved additionally evidence from unmelted high grade metamorphic rocks indicates that major reactant minerals in the fluid absent melting process principally biotite and plagioclase do not always attain equilibrium during regional metamorphism when these two circumstances occur in combination the melt does not inherit its radiogenic isotopic signature from the bulk source in a simple way in such situations the isotopic composition of the melt will be dependent on the isotopic compositions of the reactant phases and the stoichiometry of the melting reaction this study has used information from experimental studies of fluid absent partial melting in metapelites and metagreywackes to investigate the consequences of sr isotopic disequilibrium between the reactant minerals for magma composition the study demonstrates that a range of isotopically distinct magmas can arise from progressive melting of a single source that is able to undergo melting through different reactions as temperature increases when translated to the typically layered sources constituted by sedimentary and volcano sedimentary rocks this process will produce magmas characterized by sr isotope variability that reflects the differences in melting reaction stoichiometry within the different layers even with no bulk rock isotopic variability between layers this study demonstrates that the sr isotope variability commonly observed within granitic suites as well as at the grain and sub grain scale within individual magmatic bodies can be primary reflecting differences in composition between magma batches produced from the progressive melting of a single source

the vertical structure of a loop current eddy the vertical structure of a recently detached loop current eddy lce is studied using in situ data collected with an underwater glider from august to november 2016 altimetry and argo data are analysed to discuss the context of the eddy shedding and evolution as well as the origin and transformation of its thermohaline properties the lce appeared as a large body of nearly homogeneous water between 50 and 250 m confined between the seasonal and main thermoclines a temperature anomaly relative to surrounding gulf s water of up to 9 7 c was observed within the eddy core the salinity structure had a double core pattern the subsurface fresh core had a negative anomaly of 0 27 psu while the deeper saline core s positive anomaly reached 1 22 psu both temperature and salinity maxima were stronger than previously reported the saline core of caribbean origin was well conserved during its journey from the yucatan basin to the loop current and at least 7 months after eddy detachment the fresher homogeneous core resulted from surface diabatic transformations including surface heat fluxes and mixing within the top 200 m during the winter preceding eddy detachment heat and salt excess carried by the lce were large and require important negative heat fluxes and positive fresh water input to be balanced the geostrophic velocity structure had the form of a subsurface intensified vortex ring

dispersion of a tracer in the deep gulf of mexico a 25 km streak of cf3sf5 was released on an isopycnal surface approximately 1100 m deep and 150 m above the bottom along the continental slope of the northern gulf of mexico to study stirring and mixing of a passive tracer the location and depth of the release were near those of the deep hydrocarbon plume resulting from the 2010 deepwater horizon oil well rupture the tracer was sampled between 5 and 12 days after release and again 4 and 12 months after release the tracer moved along the slope at first but gradually moved into the interior of the gulf diapycnal spreading of the patch during the first 4 months was much faster than it was between 4 and 12 months indicating that mixing was greatly enhanced over the slope the rate of lateral homogenization of the tracer was much greater than observed in similar experiments in the open ocean again possibly enhanced near the slope maximum concentrations found in the surveys had fallen by factors of 104 107 and 108 at 1 week 4 months and 12 months respectively compared with those estimated for the initial tracer streak a regional ocean model was used to simulate the tracer field and help interpret its dispersion and temporal evolution model data comparisons show that the model simulation was able to replicate statistics of the observed tracer distribution that would be important in assessing the impact of oil releases in the middepth gulf