rare earth elements in the sediments of the north atlantic ocean amazon delta and east china sea reinterpretation of terrigenous input patterns to the oceans

behavior of rare earth elements in a paleoweathering profile on granodiorite in the front range colorado usa abstract a paleoweathering profile on the boulder granodiorite in northern colorado provides an opportunity to trace the behavior of rees from parent rock through a weathering profile into unconformably overlying permian sediments with progressive upward weathering of the granodiorite na2o cao sio2 ta hf co th cr sc cr th zr hf la sc zr y and la th decrease al2o3 and fe2o3t increase and tio2 mgo k2o p2o5 rb zr sc cr co hf nb ta y th u ree ti nb and zr nb increase to maximum values and then either level off or decrease lree enrichment is less in the weathering profile than in the parent granodiorite and although the parent does not have an eu anomaly or only a slight positive anomaly all samples from the weathering profile and overlying sediments have significant negative eu anomalies this observation is especially important in that it shows conclusively that a negative eu anomaly can be produced during chemical weathering of granitoids we suggest these eu anomalies are due to relative enrichment of the other rees and partial loss of eu during the breakdown of plagioclase the boulder weathering profile also has a very minor negative ce anomaly that is within error of a ce anomaly in the parent in the unweathered parent 50 of the ree are contained in sphene and in the case of la also in allanite from 10 20 of the ree are contained in apatite and biotite hornblende and from 7 10 of the hrees are in zircon with exception of eu for which feldspars contribute about 8 negligible amounts of rees occur in the feldspars in weathered samples 75 of the rees are contained in clay minerals the crossover between sphene and clay control of rees occurs over a distance of 1 m near the contact with fresh rock except for their small negative eu anomalies the clay minerals have ree patterns very similar to those of the parent rock isocon plots suggest apparent enrichments of many elements in the boulder weathering profile result from losses of na ca and si during plagioclase weathering in addition variable amounts of sr eu ta nb p and ba were lost during weathering although th u zr y th sc zr hf lu hf and ti zr may have been transferred relatively unchanged from granodiorite parent to the bulk weathering profile most other element ratios and ree distributions were significantly changed during weathering this observation implies that caution needs to be exercised when using ree patterns and element ratios to trace sediment provenance the fact that most element ratios and ree distributions also differ between fountain sediments and the bulk weathering profile may be related to one or a combination of four factors listed in order of probable decreasing importance contribution of other sources to the fountain sediments sorting of minerals during sediment deposition remobilization of elements during diagenesis and leaching of elements by water flow through the upper meter of the weathering profile

geochemistry of sediments of the ganges alluvial plains evidence of large scale sediment recycling the himalaya an amalgamation of different lithotectonic units brought together during and even before the himalayan orogeny has been subjected to various phases of denudation since the palaeogene sediments derived by erosion of these lithotectonic units in different proportions were delivered to the himalayan foreland the nature and proportions of sediments from various lithotectonic units delivered to the foreland varied in response to the prevailing tectonic and climatic conditions during the orogeny the geochemistry of sediments collected from floodplain river channels and reworked aeolian sediments from the delhi and moradabad areas of the ganges plain of the foreland basin indicates that they were derived from moderately weathered sedimentary sources further the results also suggest that the sediments are not subjected to any significant post depositional chemical weathering high tectonic instability in the source area and the geomorphology and cycles of aggradation and degradation in fluvial regimes in the ganges plain do not favor much chemical weathering homogenization of various lithotectonic units of the himalaya through several episodes of sedimentary reworking is shown by the rare earth elements ree geochemistry of the sediments the predominant source for the homogeneous sediments is likely the high himalayan crystalline or the tertiary sub himalayan sediments again the later was derived from high himalayan crystalline if so the ganges alluvial plain is geochemically a quaternary extension of tertiary sub himalaya the average composition of lithologies subjected to erosion in the himalaya appears to be better represented by the alluvial mud present in the plain

the nilgiri enderbites south india nature and age constraints on protolith formation high grade metamorphism and cooling history abstract the trident shaped nilgiri highland massif represents the deepest level exposure 9 10 kbar c 35 km palaeo depth of granulite grade lower crust in southern peninsular india the crustal section is essentially composed of garnetiferous enderbitic granulites with minor kyanite bearing gneisses quartzites and banded magnetite quartzites its deeper northern part is intruded by intermediate and basic magmatic rocks now represented by non garnetiferous enderbites garnetiferous basic granulites gabbroic to anorthositic two pyroxene granulites and pyroxenites the garnetiferous enderbitic granulites are tonalitic in composition displaying a typical calc alkaline trend and exhibit chemical features of both i type as well as s type granitoids they show moderate enrichment of lree la n 35 70 no to weakly negative eu anomalies and fairly constant levels of hree yb n 6 5 13 0 and resemble the ree spectra of tonalitic trondhjemitic granitoids and greywackes of late archaean to palaeoproterozoic age sedimentary protoliths are indicated by negative df values ranging from 1 to 4 al 2 o 3 cao na 2 o k 2 o molar ratios 1 1 high 18 o whole rock values 10 12 which match the values reported for greywackes whole rock isotope data for garnetiferous enderbites define linear arrays in the rb sr and sm nd evolution diagrams rb sr system 2460 81 ma with sr i 0 7030 5 sm nd system 2506 70 ma with nd i 0 509363 60 implying a provenance of the sedimentary precursors that was dominated by felsic volcanic rocks or tonalitic trondhjemitic granitoids of uniform isotopic composition and early proterozoic age the u pb systematics of composite zircon grains with detrital cores and metamorphic overgrowths in accord with the sm nd and rb sr errorchron ages and sm nd garnet whole rock data suggest that formation of the provenance deposition of the sedimentary precursors and subsequent high grade tectono metamorphic processes must have occurred in the short time span between 2600 and 2500 ma based on the regional geological framework the petrological geochemical and isotopic data the nilgiri granulite terrain is interpreted as a metasedimentary allochthonous unit that was thrust onto the dharwar craton during palaeoproterozoic collisional tectonics

an oligocene palynoflora from the middle shoalhaven catchment n s w and the tertiary evolution of flora and climate in the southeast australian highlands abstract well preserved spores and pollen from a number of middle oligocene sedimentary formations in the middle shoalhaven catchment n s w are correlated with the upper nothofagidites asperus lower proteacidites tuberculatus zones of the gippsland basin victoria further confirmation of this correlation comes from three sources a the relative abundances of pollen component groups reveal the nothofagidites proteacidites and myrtaceidites groups within the shoalhaven assemblage to be typical of late eocene to middle oligocene sequences b comparisons with the ratios of phyllocladidites mawsonii to gymnosperms araucariacites to gymnosperms n flemingii to other nothofagidites and myrtaceae to nothofagidites in the murray basin indicate at least an upper n asperus age and c strong geomorphic and stratigraphic evidence reported elsewhere shows that the spore and pollen bearing sediments were deposited in a basalt dammed lake between 29 32 ma the mid oligocene shoalhaven assemblage fills a significant gap in the spore pollen record of the southeast australian highlands and as a consequence there is now a continuous record of development of flora and climate for this region for nearly the entire tertiary average annual temperature and thermal seasonality appear to have been the two most significant climatic parameters to have varied throughout the southeastern highlands from the palaeocene to the miocene after which progressively drier conditions ensued

geochemistry of sediments of the peninsular rivers of the ganga basin and its implication to weathering sedimentary processes and provenance abstract geochemistry of the himalayan rivers has been a major point of contention in sedimentary geochemistry because of its global impact on ocean chemistry and climate among the himalayan rivers the ganga and its himalayan catchment have been studied extensively however the peninsular rivers constituting a significant part of the ganga basin have not received much attention heretofore in the present geochemical study of the peninsular river s sediments we have found that the initial chemical weathering of rocks in the catchment produces texturally mineralogically and geochemically diverse sediments and fluvial processes further segregate them into the geochemically contrasting coarse channel and fine grained suspended sediments the overbank sediments possess an intermediate texture and geochemistry but more towards the suspended sediments the sediment geochemistry data indicates that the peninsular river s sediments show an increase in the weathering intensity from the west banas river to the east son river along the climate gradient i e from the arid semiarid to the sub tropical condition the higher chemical index of alteration cia values of the peninsular river s sediments than the yamuna and ganga river sediments reflect the control of weatherable lithology in the tectonically stable low relief and subtropical climate condition the yamuna and ganga river sediments with lower cia values show more physical weathering in the tectonically active himalaya the suspended and overbank sediments of the yamuna and ganga rivers show an increase in their cia values after the confluence of the peninsular rivers indicating the contribution of more weathered materials by the peninsular rivers it has been found that there is a geochemical split between the channel and suspended sediments of the peninsular rivers for sharing different sources i e the dominant contribution of felsic sources to the channel and mafic sources to the suspended sediments the weathering geochemistry trace element systematics and ree patterns suggest that the dominant sources of the channel sediments of the peninsular rivers are the felsic crystallines and sedimentary lithologies of the aravalli range bundelkhand and chhotanagpur granite and gneisses and vindhyan sandstones whereas the mafic lithologies such as the deccan traps and mafic components of the felsic lithologies appear to be the major sources of the suspended sediments within the range of intermediate composition the overbank sediment chemistry reflects more contribution of the mafic sources except for the ken which shows a higher contribution of the felsic sources the geochemical split between the channel and suspended sediments of the peninsular river s sediments for the different provenances indicates differential weathering of the deccan basalts bundelkhand crystalline and vindhyan sedimentary rocks and also the hydrodynamic control of the peninsular rivers during erosion transport and deposition however the himalayan rivers do not show such contrast between the channel and suspended sediments because of the higher physical weathering and sediment mixing in the high gradient topography of the himalayan catchment

energy transport by nonlinear internal waves wintertime stratification on oregon s continental shelf often produces a near bottom layer of densefluid that acts as an internal waveguide on which nonlinear internal waves propagate shipboard profiling and bottom lander observations capture disturbances that exhibit properties of internal solitary waves bores and gravity currents wave like pulses are highly turbulent instantaneous bed stresses are 1 n m 2 resuspending bottom sediments into the water column and raising them 30 m above the seafloor the waves cross shelf transport of fluid counters the time averaged ekman transport in the bottom boundary layer in the nonlinear internal waves we have observed the kinetic energy is roughly equal to the available potential energy and is o 0 1 mj per m of coastline the energy transported by these waves includes a nonlinear advection term huei that is negligible in linear internal waves unlike linear internal waves the pressure velocity energy flux hupi includes important contributions from nonhydrostatic effects and surface displacement it is found that statistically huei 2hupi vertical profiles indicate that up z is more important in transporting energy near the seafloor while ue z dominates farther from the bottom with the wave speed c estimated from weakly nonlinear wave theory it is verified experimentally that the total energy transported by the waves hupi huei chei the high but intermittent energyflux by the waves is in an averaged sense o 100 w per m of coastline this is similar to independent estimates of the shoreward energy flux in the semidiurnal internal tide at the shelfbreak

a comparison between the generalized digital environmental model and levitus climatologies two ocean climatologies of temperature and salinity the generalized digital environmental model gdem and the climatological atlas of the world ocean are compared dynamic height fields are computed by season from each climatology for the north atlantic north pacific and indian oceans and are compared on a 1 latitude longitude grid large scale oceanographic features are generally found to be similarly represented in both climatologies gdem appears to render better representations of seasonal variability and regions of high current shear such as the gulf stream because of a different smoothing method and a finer grid spacing maps of dynamic heights from both climatologies are presented and their similarities and differences are discussed the methodology for the construction of gdem is also described in detail

early tertiary palaeogeography landform evolution and palaeoclimates of the southern monaro n s w australia the age of the southern highlands of australia has long been controversial recent field investigations around bombala in southern new south wales have shed some light on this as well as on the early tertiary palaeoclimates in southern australia late palaeocene basalts were extruded on a landscape with a relief of at least 400 m and possibly as much as 800 m showing that the region had a substantial relief by the beginning of the tertiary fluvial and lacustrine sediments deposited on the earlier or prebasaltic landscape have been preserved by the basalt and contain palynofloras and fossil wood as do sediments deposited between basalt flows in the lower parts of the basalt pile the palynomorphs are representative of the lygistepollenites balmei zone in the upper late paleocene ca 58 60 ma the pollen and fossil wood indicate the region was covered by cool temperate rainforest podocarps and araucarian conifers were significant components of these forests in addition to nothofagus ferns were prominent in some localities the fossil wood is dominated by gymnosperms comparison of the palynofloras with bioclimatic data of a number of descendant extant species has shown that most belong to the mesotherm response category with mean annual temperatures in the range 14 20 c there is little evidence that frosts were significant data from tree rings support this and show that climates were markedly seasonal the annual rings are very thin suggesting cool climates their uniformity shows that conditions varied little from year to year

influence of soil pedological properties on termite mound stability this study investigated the influence of soil properties on the density and shape of epigeous fungus growing termite nests in a dry deciduous forest in karnataka india in this environment odontotermes obesus produces cathedral shaped mounds their density shape height and volume and soil physicochemical properties were analyzed in ferralsol and vertisol environments no significant difference was observed in o obesus mound density n 2 7 mound ha 1 on average in the vertisol and ferralsol areas this study also showed that o obesus has a limited effect on soil physical properties no differences in soil particle size ph or the c n ratio and base saturation were measured whereas the c and n contents were reduced and cec was higher in termite nest soils in both environments clay mineralogical composition was also measured and showed the presence of higher amounts of smectite clays in termite nest soils which thus explained the increasing cec despite the reduced c and n content however the main difference was the shape of the termite mounds the degradation of the nests created a hillock of eroded soil at the base of termite mounds in the vertisol while only a thin layer of eroded soil was observed in the ferralsol the increased degradation of termite mounds in the vertisol is explained by the presence of smectites 2 1 swelling clays which confer macroscopic swelling and shrinking characteristics to the soil soil shrinkage during the dry season leads to the formation of deep cracks in the termite mounds that allow rain to rapidly penetrate inside the mound wall and then breakdown unstable aggregates in conclusion it appears that despite a similar abundance termite mound properties depend to a large extent on the soil properties of their environments

geochemistry and origin of ferruginous nodules in weathered granodioritic gneisses mysore plateau southern india fe nodules occur within saprolites formed from weathering of granodioritic gneisses in the rain shadow region of the mysore plateau adjacent to the sahyadri mountains in southern india these nodules and their host saprolites were studied for their geochemistry including chemical speciation to understand nodule formation and chemical redistribution processes during rock weathering from their mode of occurrence and mineralogical and geochemical data we infer that the nodules originated by a two stage process in which the initial extensive weathering of gneisses likely facilitated subsequent ferrolysis weathering and nodule formation nodules originated by precipitation of goethite hematite and gibbsite along with several amorphous phases within the matrix of weathered gneisses this is possible only under hydromorphic conditions suggesting that parts of the plateau must have gone through a humid phase prior to the present aridity in the saprolites al fe and ti become enriched because of the removal of si ca na and k however within the nodule fe ti cr and ni are deposited after their chemical transport from the saprolite titanium known for its immobile nature was also mobilized and concentrated under the conditions of nodule formation the most important elements in the nodule constitution are fe al ti and mn each having both crystalline and amorphous phases fe ti and mn oxyhydroxides grain coatings in the saprolites and discrete amorphous mn and ti phases in the nodules seem to have scavenged trace elements from the weathering profile ree were mobilized during weathering and nodule genesis in which ce and ti show a strong geochemical coherence the enrichment of only hree in saprolite and both hree and lree with significant ce in the nodule indicate the control of evolving secondary minerals in the ree redistribution during rock weathering strong enrichment of ce in the weathering profile and in nodules has important implications to the ree chemistry of river waters

internal solitary wave reflection near dongsha atoll the south china sea internal solitary wave isw reflection is rarely observed in satellite images even in the south china sea scs where the strongest and most energetic isws in the world have been observed compared to the large number of satellite images showing shoaling isw in the scs fewer than ten satellite images have been reported showing isw reflection in this study we collect recent satellite images and implement a numerical model to analyze isw reflection near dongsha atoll in the scs satellite observations show that the reflection appears to be associated with the large amplitude isws generated by strong tidal currents in luzon strait numerical simulations show that isws break when reaching the sloping bottom part of isw energy is reflected by mode 1 waves and their trailing mode 2 waves the mode 1 waves have two types long inertial gravity waves and breaking isw induced short waves they propagate quickly but induce weak vertical velocity and surface imprints mode 2 waves induce strong vertical velocity showing visible signature in satellites horizontal distribution of the energy indicates that a maximum energy of about 2 of the incident energy is contained in a single reflected wave this could explain why the reflected waves are rarely observed because reflected waves must be sufficiently large to be detected in satellite images although individual wave s energy is small in total up to 20 of the incident wave is reflected by the groups of mode 1 and mode 2 waves this suggests that isw reflection has a significant impact on energy distribution over the continental slopes

shield effect on continental weathering implication for climatic evolution of the earth at the geological timescale abstract a model sensitivity study is performed in order to explore the impact of the development of thick weathering profiles in the equatorial area on the geological evolution of climate long term climatic evolution is driven by the balance existing between solid earth degassing and continental silicate weathering the co 2 consumption through continental silicate weathering is here calculated as a function of climate based on the correlation existing with mean annual continental runoff for large drainage basins these correlations appear to be dependent on the climatic regime under mid latitude temperate climate the silicate weathering is 5 times more sensitive to continental runoff than in the warm humid equatorial belt these correlations emphasize the role of the thick weathering profiles existing in equatorial area shielding the bedrock from further weathering we use this set of relationships between runoff and silicate weathering as a function of the geoclimatic zone to explore the impact of this shield effect on the mesozoic evolution of climate using the geoclim model compared to previous work we suggest that atmospheric co 2 was generally underestimated in the past evidencing a complex interplay between the paleogeographic setting and the shield effect particularly calculated atmospheric co 2 during the early middle jurassic rises up to 1600 ppmv while it was limited to 700 ppmv when shield effect was neglected corresponding to a global warming of more than 4 c this study emphasizes the need for the building up of numerical models describing the growth of the weathering profiles that can be coupled to vegetation and climate models to investigate biogeochemical cycle and climate evolution even at the geological timescale

ree geochemistry of recent clastic sediments from the kaveri floodplains southern india implication to source area weathering and sedimentary processes abstract the kaveri river drains through archean gneissic and charnockitic terranes in south india the rare earth element ree chemistry of the floodplain sediments along with their major and trace element composition in different size fractions are discussed we observe a strong coherence between ree and tio2 contents in the sediments which is suggestive of strong control by titanite or its weathered products on the ree chemistry ree concentrations also show a general increase with decreasing size of bulk sediments different size fractions and of light and heavy mineral fractions this suggests the presence of ree in the fe oxy hydroxide surface coatings on clastic grains formed by the weathering of hornblende and titanite in the granodioritic to dioritic protoliths we also interpret the data as showing that ree patterns of clastic sediments notably eu anomaly are affected by the degree of source rock weathering as well as by the fluvial processes of sorting and mineral differentiation therefore for provenance study sediments having all granulometric grades such as the floodplain sediments are preferable because they most closely represent the source particularly when the source region suffered little chemical weathering in the present case the sediments were derived from the high standing hills of archean charnockites because of their recent uplift and physical denudation

impacts of a mesoscale eddy pair on internal solitary waves in the northern south china sea revealed by mooring array observations abstractboth internal solitary waves isws and mesoscale eddies are ubiquitous in the northern south china sea scs in this study the authors examine the impacts of mesoscale eddies on the isws transiting the northern scs deep basin that evolve from the steepening internal tide generated in the luzon strait using in situ data collected from a specifically designed mooring array from november 2013 to january 2014 an energetic mesoscale eddy pair consisting of one anticyclonic eddy ae and one cyclonic eddy ce propagated across the mooring array observations revealed that the amplitude propagation direction and speed of the transbasin isws were significantly modulated by the eddy pair when the moorings were covered by the southern portion of the ae the isw amplitudes decreased by as much as 67 because of the thermocline deepening along the wave direction and the energy divergence along the wave front when the moorings were covered by the northern portions of both eddies the amplitude of is

stream response to quaternary climate change evidence from the shoalhaven river catchment southeastern highlands temperate australia abstract luminescence ages from a flight of four paired alluvial terraces in the upper catchment of the shoalhaven river southeast highlands australia provide a record of stream behaviour throughout the late quaternary ages ranging from 7 ka in the modern floodplain to nearly 500 ka for the uppermost dated terrace allow comparisons to be made of the response of streams throughout southeastern australian to late quaternary climatic perturbations the alluvial record of the shoalhaven river highlights the broad regional synchronicity of episodes of heightened fluvial activity during oxygen isotope stage ois 5 terminating 75 ka 60 40 30 25 and 20 15 ka the shoalhaven record also shows an absence of fluvial activity during the last glacial maximum suggesting that southeastern australia was most likely dry at this time as compared to northern australia which was probably wet fluvial activity while still significant decreased substantially after approximately 60 ka suggesting a general drying of climate towards the present

weathering and global denudation a negative correlation between sediment yield and weathering history as measured by the chemical alteration cia of the suspended sediment is observed for many of the world s major rivers and other regions of denudation the weathering history is a first order control on the sediment yield of such areas termed equilibrium denudation regions for other areas data scatter with either apparent increases or decreases of sediment yield for given cia values these areas are termed nonequilibrium denudation regions low sediment yields can be attributed to moderated erosion either natural or human induced and or the incorporation of unweathered glacial debris accelerated erosion resulting in high sediment yield is primarily human induced and results from cultivation and other land use each of these effects has a profound influence on global sediment discharge from the continents pre human suspended sediment discharge from the continents is estimated to be 12 6 times 10 15 g yr or about 0 6 the

controls on intense silicate weathering in a tropical river southwestern india the silicate weathering rate swr and associated carbon dioxide consumption rate ccr in tropical silicate terrain is assessed through a study of the major ion chemistry in a small west flowing river of peninsular india the nethravati river the specific features of the river basin are high mean annual rainfall and temperature high runoff and a precambrian basement composed of granitic gneiss charnockite and minor metasediments the water samples n 56 were collected from three locations along the nethravati river and from two of its tributaries over a period of twelve months chemical weathering rate cwr for the entire watershed is calculated by applying rainwater correction using river chloride as a tracer chemical weathering rate in the nethravati watershed is estimated to 44 t km 2 y 1 encompassing a swr of 42 t km 2 y 1 and a maximum carbonate contribution of 2 t km 2 y 1 this swr is among the highest reported for granito gneissic terrains the assessed ccr is 2 9 10 5 mol km 2 y 1 the weathering index re calculated from molecular ratios of dissolved cations and silica in the river suggests an intense silicate weathering leading to kaolinite gibbsite precipitation in the weathering covers the intense swr and ccr could be due to the combination of high runoff and temperature along with the thickness and nature of the weathering cover the comparison of silicate weathering fluxes with other watersheds reveals that under similar morpho climatic settings basalt weathering would be 2 5 times higher than the granite gneissic rocks c 2012 elsevier b v all rights reserved

remote sensing evidence for baroclinic tide origin of internal solitary waves in the northeastern south china sea 1 evidence for baroclinic tide origin of internal solitary waves isws in the northeastern south china sea is presented based on 116 internal wave packets observed in satellite images from 1995 to 2001 these wave packets can be divided into two types a single wave isw packet containing only one isw with without an oscillating tail and a multiple wave isw packet composed of a group of rank ordered isws all of the 22 single wave isw packets occur in the deep water zone it is suggested that the isws instead of being generated by the lee wave mechanism are developed by nonlinear steepening of the baroclinic tides which are produced by the strong tidal currents flowing over a ridge in luzon strait this suggestion is verified by an ers 2 sar image which records such an evolution process from a baroclinic tide to a single isw in its spatial domain

controls on post mid cretaceous landscape evolution in the southeastern highlands of australia insights from numerical surface process models the tectonic and geomorphic evolution of the southeastern australian highlands has been a subject of controversy among geophysicists geologists and geomorphologists for several decades we employ a numerical surface process model that includes long range fluvial transport hillslope diffusion and landsliding in order to quantitatively assess the tectonic lithological and structural controls on the landscape evolution and denudation history of se australia we constrain fluvial erosion parameters for our model by fitting river profiles rockfall and landsliding are the most important processes controlling the concentration of erosion in river valleys we therefore model hillslope evolution using a very low diffusion coefficient and a threshold slope for landsliding the initial prebreakup topography of the highlands provides a fundamental control on their subsequent evolution together with the style and rate of fluvial incision secondary controls are exerted by lateral variations in lithology and local tectonic uplift along faults our modeling results indicate that 1 the observed highlands morphology requires that the drainage divide was established at its present location prior to opening of the tasman sea whether the divide is inherited from paleozoic orogeny or resulted from mesozoic syn rift uplift cannot be established however 2 in contrast to traditional interpretations escarpment retreat does not appear to be the fundamental process eroding the highlands and 3 the observed barbed river drainage may be imprinted as a result of lithological variation it does not necessarily evolve through capture the driving mechanism that is most consistent with the inferred uplift pattern of the southeastern highlands appears to be magmatic underplating

role of mesoscale eddies in modulating the semidiurnal internal tide observation results in the northern south china sea abstractthe role of mesoscale eddies in modulating the semidiurnal internal tide sit in the northern south china sea scs is examined using the data from a cross shaped mooring array from novem

temporal variability of internal tides in the northeast south china sea 1 the northeast south china sea is perhaps the largest internal tide energy source in the world the temporal variability of internal tides was investigated on the basis of 8 month moored acoustic doppler current profiler observations on the continental slope at the dongsha plateau the daily amplitude and phase of diurnal and semidiurnal internal tides were determined from complex demodulation and the dominant spatial and temporal patterns were extracted with empirical orthogonal function eof analysis the eof modal structures showed good agreement with the normal mode solution although vertical phase propagations were apparent the first semidiurnal eof mode corresponded to the first normal mode and the first two diurnal eof modes corresponded to the second and third normal modes respectively the modal structure and energy flux also were consistent with previous observations near the shelf break from the asian seas international acoustic experiment on the other hand the amplitudes of diurnal and semidiurnal eof modes both indicated large irregular fortnightly variations that were not phase locked incoherent with astronomical forcing the study highlighted the importance of incoherent internal tidal motion which accounted for about three fourths of the observed tidal energy

baroclinic tidal sea level from exact repeat mission altimetry abstracta near global model for the sea surface expression of the baroclinic tide has been developed using exact repeat mission altimetry the methodology used differs in detail from other altimetr

three dimensional numerical simulation of m2 internal tides in the east china sea the east china sea and adjacent seas are one of the most significant generation regions of the m 2 internal tide in the world s oceans in the present study we investigate the distribution and energetics of the m 2 internal tide around the continental shelf edge in the east china sea using a three dimensional numerical model the numerical experiment shows that m 2 internal tides are effectively generated over prominent topographic features such as the subsurface ridges in the bashi luzon and tokara straits the ridges along the ryukyu island chain and the continental shelf slope in the east china sea the former particularly so all of these topographic features are characterized by steep slopes at the depth of the thermocline onto which the m 2 barotropic tide is almost normally incident the m 2 internal tides propagating away from these multiple source regions interfere with each other to create a complicated wave pattern it is found that the calculated pattern of the m 2 internal tide agrees well with topex poseidon altimeter observations the conversion rate from m 2 barotropic to baroclinic energy over the whole analyzed model domain is estimated to be 35 gw roughly 10 of the energy in the m 2 surface tide incident on the prominent topographic features is converted to the m 2 internal tide although about half of the m 2 internal tidal energy is subject to local dissipation in close proximity to the generation sites

numerical modelling of tidally generated internal wave radiation from the andaman sea into the bay of bengal abstract semi diurnal internal waves generated by tides in a high resolution numerical model that includes the andaman sea archipelago are found to propagate into the central bay of bengal and reach the coasts of india and sri lanka the waves are also present in subsurface temperature records from rama moorings and their propagation speed across the bay of bengal agrees well with satellite remote sensing from modis imagery in spite of the hydrostatic nature of the model the internal waves are simulated by a fully coupled ocean atmosphere prediction system exchanging surface fluxes between the air and sea at high frequency and at high resolution for the ocean a hydrostatic model including diurnal and semi diurnal tides provides a 2 km resolution representation of the entire bay of bengal in the ocean model simulations the semi diurnal internal waves interact with the mesoscale circulation and surface waves and modify the flow and the stratification by comparing coupled ocean wave model runs with tides and without tides but forced by identical surface fluxes from the atmosphere it is demonstrated that the inclusion of diurnal and semi diurnal tides act to cool the core of the thermocline while increasing the temperature above and below it along the pathway of the internal waves a result that likely is due to vertical mixing by the waves

soil production on a retreating escarpment in southeastern australia the functional dependence of bedrock conversion to soil on the overlying soil depth the soil production function has been widely recognized as essential to understanding landscape evolution but was quantified only recently here we report soil production rates for the first time at the base of a retreating escarpment on the soil mantled hilly slopes in the upper bega valley southeastern australia concentrations of 10 be and 26 al in bedrock from the base of the soil column show that soil production rates decline exponentially with increasing soil depth these data define a soil production function with a maximum soil production rate of 53 m m y under no soil mantle and a minimum of 7 m m y under 100 cm of soil thus constraining landscape evolution rates subsequent to escarpment retreat the form of this function is supported by an inverse linear relationship between topographic curvature and soil depth that also suggests that simple creep does not adequately characterize the hillslope processes spatial variation of soil production shows a landscape out of dynamic equilibrium possibly in response to the propagation of the escarpment through the field area within the past few million years in addition we present a method that tests the assumption of locally constant soil depth and lowering rates using concentrations of 10 be and 26 al on the surfaces of emergent tors

double ridge internal tide interference and its effect on dissipation in luzon strait abstractluzon strait between taiwan and the philippines features two parallel north south oriented ridges the barotropic tides that propagate over these ridges cause strong internal waves and dissipation the energy dissipation mechanisms and the role of the baroclinic wave fields in this dissipation are investigated using numerical simulations with the massachusetts institute of technology general circulation model mitgcm the model is integrated over two dimensional configurations along a zonal transect at 20 6 n for a maximum duration of a spring neap cycle nearly all dissipation occurs at the steep ridge crests due to high mode turbulent lee waves with horizontal scales of several kilometers and vertical scales of hundreds of meters the spatial structure and timing of the predicted velocities and dissipation agree with observations and confirm the existence of these lee waves the lee wave strength is greatly affected by the internal waves generated at the other ridge when semidiurnal barotropic

phosphorus distribution and fractionation during weathering of amphibolites and gneisses in different climatic setups of the kaveri river catchment india abstract phosphorus distribution and fractionation during weathering of rocks are seminal to its availability to the life system here the p fractionation pattern is reported in weathering profiles of two different rock types i e amphibolites and granitic gneisses subjected to semi arid and humid climatic conditions in the catchment of the kaveri river southern india known for its fertile flood plain and delta weathering profiles developed on the two rock types were analysed for evaluating the intensity of chemical weathering using major ion geochemistry and for accompanying p fractionation the chemical index of alteration cia and the mineralogy of different zones of the weathering profiles show that profiles under humid climatic conditions are more weathered than those under semi arid conditions it was also found that p present dominantly as the apatite inorganic p aip fraction in the bedrocks was converted into non apatite inorganic p naip and organic p op both of which increase with progressive weathering the two major rock types show a very similar pattern of p fractionation during weathering which is similar to those observed in soil chronosequences however the transfer of p from aip to op and naip is near total in both rock types under humid conditions of weathering under semi arid conditions a part of aip was also available in the most weathered zone thus the lithology of the bedrock has little and climate a dominant control on p fractionation during rock weathering it was also observed that there is a net loss of total p during the weathering associated fractionation that could be attributed to the incorporation into biologically available forms and their subsequent removal to the fertile floodplains and delta in an undisturbed riverscape

fluvial archives a valuable record of vertical crustal deformation abstract the study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms but also for identifying the nature of crustal deformation and its history in recent decades geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens here we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions the effects of horizontal deformation are not addressed channel long profiles have received considerable attention in the literature and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady state characteristics then we review the literature dealing with the transient response of rivers to tectonic perturbation through the production of knickpoints propagating through the drainage network inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories finally we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes as well as the erosional imprint of tectonic forcing sedimentary deposits such as fluvial terrace staircases are also considered as a classical component of tectonic geomorphology we show that these studies have recently benefited from rapid advances in dating techniques allowing more reliable reconstruction of incision histories and estimation of incision rates the combination of progress in the understanding of transient river profiles and larger more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace profile correlation i e extrapolation of local data to entire profiles finally planform changes in fluvial systems are considered at the channel scale in alluvial rivers and regional level in terms of drainage reorganisation examples are given of how numerical modelling can efficiently combine with topographic data to shed new light on the dis equilibrium state of drainage systems across regional drainage divides

turbulent dissipation on the margins of the south china sea 1 measurements of turbulence along the continental slope shelfbreak and shelf of the northern south china sea are presented from a 10 day measurement program during april 2005 the shelfbreak region was characterized by a deep stratification that appears to be typical of the late winter monsoon this appears to shift the wave field at the shelfbreak from the soliton like depression anomalies observed in previous years to a more complex wave field supporting high frequency waves in both upper and lower depth intervals of the water column on average 30 of the depth integrated turbulent dissipation occurs within 10 m of the bottom where baroclinic energy is preferentially dissipated dissipation levels reaching 50 mw m2 are an order of magnitude larger than those attainable through frictional dissipation of the local barotropic tide and an order of magnitude larger than levels typical in the open ocean

weathering of lower crustal rocks in the kaveri river catchment southern india implications to sediment geochemistry in the upper catchment of the kaveri river in the sahyadri mountains of southern india middle to lower crustal archean granulite grade mafic and felsic rocks with similar structures and textures are exposed under the conditions of active tectonics high rainfall and thick tropical vegetation occurrence of the two major rock types in close association under identical geological geographical and biological conditions provides an uncommon situation for the study of weathering elemental mobilization and sediment generation processes field observations mineralogical and geochemical data including major trace and rare earth elements ree of fresh rocks and variably weathered saprolite samples suggest that close association of mafic and felsic rocks accelerates the denudational processes by early weathering of mafic minerals in felsic rocks and mafic rocks in the terrain due to differential weathering of rocks unweathered to less weathered felsic grains are likely transferred to the coarser fraction of fluvial sediments deposited on the floodplains of the river imposing an upper continental crust ucc geochemical signature it is found that during chemical weathering in addition to other factors weatherability of host minerals of ree control the mobility of ree in the weathering profile it is suggested from the observations on the weathering process and on the geochemistry of derivative sediments that in a tectonically active system with a climate maximum as in sahyadris an equilibrium could be dynamically maintained between weathering and erosional regimes also we infer from our study that there exist certain commonalities between surface denudational and mantle magmatic geochemical differentiation processes similarity of these processes therefore may have implication to common ucc like geochemistry of post archean sediments

late quaternary erosion in southeastern australia a field example using cosmogenic nuclides late quaternary rates of apparent soil production bedrock incision and average erosion are determined for the southeastern highlands of australia using in situ produced cosmogenic nuclide concentrations of 10 be and 26 al apparent soil production rates define a steep inverse exponential function of soil depth with a maximum of 143 m ma 1 under zero soil depth there were no observed soil depths between about 25 cm and zero however such that the maximum observed rate is about 50 m ma 1 the bredbo river catchment average erosion rate is 157 1mm a 1 and is similar to the average hillslope erosion rate of 167 1mm a 1 bedrock incision rates average 9 mma 1 and suggest that the higher rates of hillslope erosion may be in response to a pulse of incision perhaps generated by knickpoint propagation bedrock erosion rates inferred froma tor profile average 3 8 mma 1 with higher rates on other more weathered tor tops an aboveground tor profile of nuclide concentrations is consistent with a simple model of rapid stripping of the surrounding saprolite supporting the view that at least one episodic period of increased denudation has affected the landscape evolution of the highlands we test this hypothesis by using a simple landscape evolution model to reasonably predict the spatial variation of soil depth as well as the emergence of tors r 2001 elsevier science ltd and inqua all rights reserved

energy of nonlinear internal waves in the south china sea 1 four sets of adcp measurements were taken in the south china sea scs these results were combined with previous satellite observations and internal tide numerical model results analysis suggests that strong internal tides are generated in luzon strait propagate as a narrow tidal beam into the scs are amplified by the shoaling continental slope near tungsha island become nonlinear and evolve into high frequency nonlinear internal waves niw internal waves in the scs have geographically distinct characteristics 1 west of luzon strait the total internal wave energy eiw is 10 that predicted by garrett munk spectra egm levine 2002 there is no sign of niw 2 near tungsha island eiw 13 egm strong nonlinear and high harmonic tides are present repetitive trains of large amplitude niw appear primarily at a semidiurnal periodicity with their amplitudes modulated at a fortnightly tidal cycle the rms vertical velocity of niw shows a clear spring neap tidal cycle and is linearly proportional to the barotropic tidal height in luzon strait with a 1 85 day time lag consistent with the travel time of internal tides from luzon strait to tungsha island 3 at the northern scs shelfbreak eiw 4 egm single depression waves are found but no multiple waves packets are evident 4 on the continental shelf eiw 2 egm both depression and elevation niw exist

on the generation and evolution of nonlinear internal waves in the south china sea the nonhydrostatic regional ocean modeling system is applied to the nonlinear internal waves or solitons that are generated at the luzon ridge in the south china sea the luzon ridge near the batan islands is represented by an idealized ridge with a height of 2 6 km on a flat bottom model runs are performed for various ridge shapes and a symmetric tidal forcings the model is in the mixed tidal lee wave regime the barotropic tide over the ridge generates first mode waves through the internal tide release mechanism westward traveling solitons emerge from these first mode waves through nonlinear steepening in the internal tide release mechanism asymmetric tides with strong eastward currents can generate strong westward solitons the eastward current creates an elevation wave with a higher energy density west of the ridge and as soon as the current slackens the wave is released westward on its backslope strong solitons develop the energy density is further enhanced by nonlinearities such as differences in phase speeds and energy fluxes related to lee waves a modal and harmonic decomposition shows the generation of vertical modes and higher temporal harmonics and indicates significant wave wave interaction e g triads in the mixed tidal lee wave regime more energy is contained in the first mode compared to the higher modes hence linear internal tide beams are less well defined and strong solitons develop

formation and diagenesis of a sub huronian saprolith comparison with a modern weathering profile an early proterozoic paleosol that preserves archean granite protolith textures occurs beneath the lorrain formation in the early proterozoic huronian supergroup near ville marie quebec textural mineralogical and geochemical comparisons between this saprolith and a modern weathering profile developed on the devonian toorongo granodiorite in eastern australia indicate similarities that can be attributed to the effects of primary weathering reactions the comparison also reveals anomalous features at ville marie that are caused by diagenetic reactions between the weathered granite and meteoric waters k metasomatism in the form of sericite replacement of kandites is ubiquitous in the ville marie saprolith zone and is ascribed to reaction of low na k meteoric waters with the weathered profile as they moved along a relatively permeable unconformity surface earlier diagenetic reactions may have produced calcite alteration occurring in a thin zone at the base of the profile thought to represent the po

structure propagation and mixing of energetic baroclinic tides in mamala bay oahu hawaii abstract large semidiurnal vertical displacements 100 m and strong baroclinic currents 0 5 m s 1 several times as large as barotropic currents dominate motions in mamala bay outside the mouth of pearl harbor hawaii during september 2002 the authors sought to characterize them with a 2 month mclane moored profiler deployment and a 4 day intensive survey with a towed ctd adcp and the research vessel r v revelle hydrographic sonar spatial maps and time series of turbulent dissipation rate diapycnal diffusivity k isopycnal displacement velocity u energy e and energy flux f are presented dissipation rate peaks in the lower 150 m during rising isopycnals and high strain and shows a factor of 50 spring neap modulation the largest k values in the western bay near a submarine ridge exceed 10 3 m2 s 1 the m2 phases of and u increase toward the west implying a westward phase velocity cp 1 m s 1 and horizontal wavelength 60 km consistent with theoretical mode 1 values these phase

energy flux and dissipation in luzon strait two tales of two ridges abstractinternal tide generation propagation and dissipation are investigated in luzon strait a system of two quasi parallel ridges situated between taiwan and the philippines two profiling moorings deployed for about 20 days and a set of nineteen 36 h lowered adcp ctd time series stations allowed separate measurement of diurnal and semidiurnal internal tide signals measurements were concentrated on a northern line where the ridge spacing was approximately equal to the mode 1 wavelength for semidiurnal motions and a southern line where the spacing was approximately two thirds that the authors contrast the two sites to emphasize the potential importance of resonance between generation sites throughout luzon strait baroclinic energy energy fluxes and turbulent dissipation were some of the strongest ever measured peak to peak baroclinic velocity and vertical displacements often exceeded 2 m s 1 and 300 m respectively energy fluxes exceeding 60 kw m 1 were measured at spring tide at the wester

long term drainage evolution in the shoalhaven catchment southeast highlands australia the long term evolution of streams in the shoalhaven catchment of southeast new south wales has been a contentious issue for decades several authors have suggested that the shoalhaven river was captured at the sharp eastward bend near tallong this has been used as evidence for the westward migration of the east australian divide in this area other workers however have argued that capture did not occur and that the location of the divide has been stable throughout the tertiary a vast sheet of sediments which spread across and infill a palaeovalley network cut into a broad undulating plain in the middle shoalhaven catchment provides a record of stream behaviour since at least the start of the tertiary this record shows that the shoalhaven river and many of its tributaries have maintained almost the same courses since at least the very early tertiary this provides strong evidence against the capture hypothesis the record further suggests that during the paleogene these streams were graded to a level within the southeast australian highlands their depths of incision thus cannot be used as evidence for the extent of uplift of the southeast australian highlands during this time

alluvium of antiquity polycyclic terraces in a confined bedrock valley confined river valleys are not the localities where long term preservation of alluvium would be expected the 25 km long low gradient 0 0014 m m 1 confined valley setting of the shoalhaven river has archived alluvium of middle pleistocene age to maintain a relatively uniform channel as an efficient conduit for a wide range of flows in a confined bedrock valley of variable morphology single grain optically stimulated luminescence osl dating has identified polycyclic terraces up to 193 ka in age marine isotope stage mis 7 with lower terrace remnants dating from 173 140 ka mis 6 and 106 ka mis 5 holocene alluvium 2 3 5 ka in age caps these old pleistocene units and a well constrained combination of one dimensional and two dimensional hydraulic modelling demonstrates that these polycyclic terraces are clearly within reach of the modern hydrological regime the 106 ka terrace at 17 m above low flow is inundated by floods recurring on average every 20 years and the 140 193 ka terraces at 20 22 m are overtopped every 50 100 years these ancient diachronous landforms exhibit complex depositional histories and are on lapped by longitudinal benches of modern sand and gravel their polycyclic nature appears to be a response to flow reduction using alluvium to adjust the boundary of the otherwise inflexible morphology of a bedrock gorge

evolution from estuary to delta alluvial plain morphology and sedimentary characteristics of the shoalhaven river mouth southeastern australia abstract the shoalhaven river in southern new south wales nsw drains a catchment of 7000 km2 forming a barrier estuary at its mouth with a prograded strandplain to its north previous coring and dating across the floodplain and adjacent strandplain indicate progressive infill of the estuarine basin over the past 7000 years over this time the system transitioned from a wave dominated estuary to a wave dominated delta the shoalhaven river appears to have initially discharged to the sea at crookhaven heads until it adopted a more direct route through an intermittently open mouth at shoalhaven heads construction of berrys canal in 1822 now permanently links the shoalhaven river to the adjacent smaller crookhaven river airborne lidar reveals details of topography of prominent levees and meander scroll bars that flank the lower reaches of the river and beach foredune ridges to the north sedimentological and mineralogical characteristics of modern sediment samples collected from the river channel the beach and the barrier reveal that the shoalhaven river is dominated by quartz sand along its predominantly straight course through the infilled estuarine plains this is in contrast to the tripartite classification of sedimentary depositional environments comprising sandy fluvial delta central mud basin and sandy marine barrier that characterised the initial wave dominated estuary 7000 years ago and is typical of most barrier estuaries in nsw grain size decreases downstream and sands have a higher feldspar content and angularity than is typical of marine sand that has been reworked in the nearshore this fluvially derived component is delivered to the coast intermittently by floods that re open shoalhaven heads as shown by retrospective analysis of aerial photography and satellite imagery grain size decreases with distance alongshore from the river mouth indicating that these sands are transported north by longshore drift to augment a gradual onshore delivery of sand within this coastal compartment scanning electron microscopy of selected grains implies that this fluvial sand has been contributing to incremental formation of beach ridges for much of the past 3000 years since the estuarine basin has been largely infilled with a slight detectable acceleration in the rate of progradation

mobilization and re distribution of major and trace elements during extreme weathering of basalt in hainan island south china major trace and organic elements of a laterite profile developed on neogene basalts in northern hainan island south china were reported in this paper the aim of which was to investigate element mobilization and re distribution during extreme weathering the results indicate that most of the elements have been mobilized and transferred downwards along the profile by aqueous solution organic matter om can significantly improve the transport of insoluble elements among all the elements th is the least mobile as for the general conservative elements during incipient chemical weathering such as fe ti zr hf nb and ta the removals are up to 20 40 in the upper profile however these elements behave as conservatively as th in the lower profile in the middle profile oxic environment occurs accompanied with significant om decomposition the mn and ce transferred downward are readily oxidized into insoluble mn iv and ce iv and precipitate in the oxic front important om decomposition decreases the capacity of transfer of insoluble elements in aqueous solution consequently al significantly precipitates in the oxic front and rees with the exception of ce precipitate largely in the omdepleted layers co and u are also concentrated in the oxic front in association with mn and ce respectively however cr shows a negative correlation with mn because its response to redox condition changes is reversed from that of mn mn oxides hydroxides fe oxides hydroxides and secondary phosphate minerals other than clay minerals are potential hosts for rees except for ce in the profile rees with high concentrations in the profile seem closely associated with mn oxides hydroxides remarkable highly correlated ce and gd anomalies are observed in the profile ce anomalies are caused by ce precipitation in the oxic environment and successive decomposition of organic matter gd anomalies are likely to have resulted from lower stability constants of gd om complexes compared to those of neighboring rees the overall elemental behaviors in this profile suggest that organic matter plays a very important role in the mobilization and re distribution of the elements during extreme weathering

effects of kuroshio intrusions on nonlinear internal waves in the south china sea during winter 1 during winter the kuroshio tends to cross luzon strait penetrating the northeastern south china sea where it forms energetic mesoscale structures luzon strait is also a site where westward propagating large amplitude internal waves are generated we describe observations of these waves acquired in the deep basin of the south china sea during the winter of 2010 2011 with the goal of assessing the influence of mesoscale variability on their properties combining tidal current simulations with an internal wave generation and evolution model we obtain time series of deviations between our observations and the model simulations these deviations are analyzed in terms of mesoscale variability based on the data assimilated hybrid coordinate ocean model hycom simulations we find that simplified models of nonlinear internal wave response to changes in horizontal stratification gradients and vertical shear provide at best weak simulations of amplitude modulation in contrast to these results deviations of internal wave arrival time occurring up to 2 h early during kuroshio inflows are quite well simulated when derived from integration of the first internal mode phase speed along two dimensional ray traced paths using hycom simulations of velocity and density fields together with bathymetry refraction of the internal waves by kuroshio intrusions can lead to substantial distortion of the paths sufficient to provide a potential explanation for the apparent suppression of waves during previous winter measurements our results suggest that the internal wave field can be a sensitive indicator of mesoscale variability in luzon strait and the northeastern south china sea

prototypical solitons in the south china sea 1 surface signatures associated with non linear internal waves are often seen in satellite images of the western south china sea scs slope and shelf observation in the deep sea to the east are rare here we report on the evolution of an energetic packet as it propagated through the deep central basin of the scs toward the western slope and shelf the waves have amplitudes estimated at 170 m half widths of 3 km and phase speeds of 2 9 0 1 m s faster than the mode 1 linear phase speed of 2 6 m s the shape and observed phase speed were consistent with the korteweg devries kdv model over the 65 km path that they were tracked the intrinsic velocity shear of the waves is small compared to pre existing shears and the waves exhibit weak turbulence the kdv fit and a satellite derived estimate of horizontal wave extent imply a westward energy flux of 4 5 gw for each crest

rare earth element distributions among minerals in a granodiorite and their petrogenetic implications a study of the distribution of lanthanide rare earths in a granodiorite from the eastern peninsular ranges batholith southern california reveals that a large fraction of the ree in this rock resides in the accessory phases sphene and allanite the minerals plagioclase alkali feldspar biotite epidote and apatite each contribute approximately 1 or less of each ree to the whole rock with the exception of eu for which plagioclase contributes 7 sphene and allanite together contain 80 to 95 of each ree each of these phases is zoned in ree concentration with substantial decreases from core to margin textural observations argue for relatively early saturation and precipitation of sphene and allanite in the magma ree zoning trends in sphene and allanite and unexpectedly low ree concentrations in largely later crystallizing minerals such as feldspar indicate that the precipitation of sphene and allanite significantly reduced ree concentrations in residual melts these results illustrate the potential that sphene and allanite have for controlling the behavior of ree in granitic magmas available information collectively suggest that the sampled granodiorite existed as a complete melt that the ree contained in the assemblage of phases were derived by direct crystallization from the melt and that the melt behaved essentially as a closed system once crystallization of the phases now present began close correspondences between the major and trace element chemistries of the granodiorite and phenocryst poor lavas from similar tectonic settings support these conclusions the ree pattern of the granodiorite melt appears to have originated at depth and is characteristic of its source regions and derivation mechanism the high liquidus temperature of a granodiorite melt 1000 c indicates the importance of mantle derived components within the sources of batholithic magmas in the peninsular ranges

a review of internal solitary wave dynamics in the northern south china sea abstract the current research into internal solitary waves isws and the related dynamic processes in the northern south china sea scs are reviewed in this paper this unique wave phenomenon did not draw much interest until about one decade ago and is now one of the hot topics in the field of wave dynamics three methods of investigation are summarized in the paper namely remote sensing images in situ measurements and numerical simulations previous works have primarily been based on one or two of these methods and have provided great insights into such wave phenomena the lifetime of an isw in the northern scs from its origin in the luzon strait ls through to its formation and evolution in the deep basin and its transformation near the shelf break up until its dissipation on the continental shelf is summarized with the illustration of different investigation approaches various factors that can affect the wave generation processes are summed up as well such factors as are barotropic tides in the ls kuroshio intrusion temporal and spatial variation of stratification and the modulation of the western ridge in the ls can significantly alter the wave fields and are extensively discussed

environmental geochemistry and quality assessment of surface and subsurface water of mahi river basin western india the hydrogeochemical study of surface and subsurface water of mahi river basin was undertaken to assess the major ion chemistry solute acquisition processes and water quality in relation to domestic and irrigation uses the analytical results show the mildly acidic to alkaline nature of water and dominance of na and ca2 in cationic and hco3 and cl in anionic composition in general alkaline earth elements ca2 mg2 exceed alkalis na k and weak acids hco3 dominate over strong acids so42 cl in majority of the surface and groundwater samples ca2 mg2 hco3 is the dominant hydrochemical facies both in surface and groundwater of the area the weathering of rock forming minerals mainly controlled the solute acquisition process with secondary contribution from marine and anthropogenic sources the higher concentration of sodium and dissolved silica high equivalent ratios of na k tz na k cl and low ratio of ca2 mg2 na k suggest that the chemical composition of the water is largely controlled by silicate weathering with limited contribution from carbonate weathering and marine and anthropogenic sources kaolinite is the possible mineral that is in equilibrium with the water implying that the chemistry of river water favors kaolinite formation assessment of water samples for drinking purposes suggests that the majority of the water samples are suitable for drinking at some sites concentrations of tds th f no3 and fe are exceeding the desirable limit of drinking however these parameters are well within the maximum permissible limit except for some cases to assess the suitability for irrigation parameters like sar rsc and na were calculated in general both surface and groundwater is of good to suitable category for irrigation uses except at some sites where high values of salinity na and rsc restrict its uses

speed and evolution of nonlinear internal waves transiting the south china sea abstract in the south china sea scs 14 nonlinear internal waves are detected as they transit a synchronous array of 10 moorings spanning the waves generation site at luzon strait through the deep basin and onto the upper continental slope 560 km to the west their arrival time speed width energy amplitude and number of trailing waves are monitored waves occur twice daily in a particular pattern where larger narrower a waves alternate with wider smaller b waves waves begin as broad internal tides close to luzon strait s two ridges steepening to o 3 10 km wide in the deep basin and o 200 300 m on the upper slope nearly all waves eventually develop wave trains with larger steeper waves developing them earlier and in greater numbers the b waves in the deep basin begin at a mean speed of 5 greater than the linear mode 1 phase speed for semidiurnal internal waves computed using climatological and in situ stratification the a waves travel 5 10 faster than b waves until they reach

behavior of major and trace elements during weathering of sericite quartz schist abstract two regolith profiles developed on the sericite quartz schist in subtropical humid environment were selected to investigate behaviors of major and trace elements during weathering in mengman gold deposit of yunnan province china one profile located in the mining district sheared by a fault and the other was outside the mining area which represented the normal weathering profile on the schist regolith samples were collected in both profiles sequentially thirteen major oxides and 23 trace elements including ree were analyzed and their behaviors were compared in these two profiles based on the idea that immobile element is just a relative notion we presented a method of immobile plateau to determine immobile elements during each stage in a progressive geochemical process and used mass ratio mr to calculate the percentage of gain or loss x gp of each element during the whole process in both profiles only tio 2 was immobile during the whole weathering the regolith profile formed on the mineralized schist recorded the weathering process more sensitively than the regolith profile on the normal schist ree was mobile and fractionated during the schist weathering lree was loss in mass during the soil development stage which resulted from the chemical leaching but was gain in mass during the pedogenesis stage because of the preferential absorption of soil to lree the lree depletion near the fault during weathering was the collective effects of chemical leaching and physical accumulation hfse were all mobile in the mineralized regolith profile especially near the fault but nb ta and zr hf were covariant in both profiles during the schist weathering

generation and propagation of baroclinic tides modified by the kuroshio in the luzon strait 1 using a three dimensional model with idealized settings this study evaluated the effect of the kuroshio on the generation and propagation of semidiurnal m2 and diurnal k1 baroclinic tides bcts in the luzon strait ls the influences of the varied kuroshio transport the location of the kuroshio and the separation distance of the two meridional ridges were investigated the absence of the kuroshio in the model leads to 30 decreases in the westward baroclinic energy flux fbcx emanating from the west slope of the east ridge compared to the fbcx with the presence of the kuroshio compared to the fbcx without the kuroshio s influence the westward fbcx is increased by 20 40 when the kuroshio is located in either the middle or the west portions of the ls whereas both the westward and eastward fbcx are 25 40 decreased as the kuroshio is moved to the east of the east ridge the wavelength of the mode 1 m2 bct is similar to the separation distance of the two ridges favoring a resonance generation for m2 rather than k1 bcts the increase of the kuroshio transport from 20 to 30 sv 1 sv 106 m3 s 1 enhances the density front but weakens the westward fbcx owing to the effects of energy advection and lateral friction from the kuroshio the influence of the kuroshio on the westward fbcx of k1 is opposite of that on m2 the characteristic slope of k1 is closer to the isopycnal slope across the kuroshio than m2 thereby causing the discrepancy

the generation and evolution of nonlinear internal waves in the deep basin of the south china sea abstracttime series observations of nonlinear internal waves in the deep basin of the south china sea are used to evaluate mechanisms for their generation and evolution internal tides are generated by tidal currents over ridges in luzon strait and steepen as they travel west subsequently generating high frequency nonlinear waves although nonlinear internal waves appear repeatedly on the western slopes of the south china sea their appearance in the deep basin is intermittent and more closely related to the amplitude of the semidiurnal than the predominant diurnal tidal current in luzon strait as the internal tide propagates westward it evolves under the influence of nonlinearity rotation and nonhydrostatic dispersion the interaction between nonlinearity and rotation transforms the internal tide into a parabolic or corner shape a fully nonlinear two layer internal wave model explains the observed characteristics of internal tide evolution in the deep basin for different representative forcing cond

diurnal and semidiurnal internal tide energy flux at a continental slope in the south china sea 1 barotropic surface and baroclinic internal tides were measured at four mooring sites during a field investigation of acoustic propagation characteristics and physical oceanography in the northern south china sea the mooring positions were in a line moving up the shallow portion of a continental slope at water depths between 350 and 85 m using time series of temperature and velocity at several depths 1 month series of semidiurnal and diurnal species internal tidal energy flux vectors were computed for three sites with a 14 day series computed for the fourth shallow site the internal tides had a temporal signature that was not in complete accord with the barotropic tides showing an enhancement of diurnal internal tides with respect to semidiurnal bathymetric slope barotropic tidal fluid particle trajectories and scale of generation site versus internal tide wavelength are investigated as possible causes of the differing response of the species

simulations of internal solitary wave interactions with mesoscale eddies in the northeastern south china sea abstractwith the combined analysis of synthetic aperture radar image and satellite altimeter data collected in the northeastern south china sea scs this study found one type of distorted phenomenon of internal solitary wave isw with the long front caused by the oceanic mesoscale eddy motivated by these satellite observations the authors carried out numerical experiments using the fully nonhydrostatic and nonlinear mitgcm to investigate the perturbation of isws by an isolated cyclonic or anticyclonic eddy the results show that the isw front is distorted by these oceanic eddies due to the retardation and acceleration effects at their two sides the isw energy along the front is focused onto scattered from the wave fragment where a concave convex pattern is formed and the previously accumulated energy in the focusing region is gradually released after the isw propagates away from the eddies the isw amplitude is modulated greatly by the eddies due to the energy redistribution along the front se

internal tide radiation from the luzon strait the m2 k1 and o1 internal tides originating in the luzon strait are investigated using the sea surface height measurements by multiple satellites ers 2 envisat topex poseidon jason 1 2 and geosat follow on a plane wave fit method is used to resolve multiple internal tides in arbitrary horizontal directions the luzon strait is an energetic internal tide generation site and radiates internal tides both westward into the south china sea scs and eastward into the western pacific wp in the scs the k1 and o1 internal tides propagate over 1600 km reaching the vietnam coast in the wp they propagate over 2500 km and arrive to the mariana ridge and guam the k1 and o1 internal tides refract toward the equator during propagation the m2 internal tides in the scs bifurcate into two beams the northwestward beam is coincident with the frequent occurrence of internal solitary waves in this region implying their causative relation the phase speeds inferred from the altimetric along beam propagation agree with the theoretical values due to the influence of the earth s rotation the k1 and o1 phase speeds decrease remarkably from high to low latitudes for the diurnal internal tides the eastward radiation is about 50 greater than the westward radiation for m2 the westward radiation is about two times the eastward radiation the altimetric energy fluxes are about 50 of those in numerical model simulations

climatically controlled river terrace staircases a worldwide quaternary phenomenon a comparison of fluvial terrace sequences from around the world based on data collected as part of international geoscience programme igcp project no 449 has revealed significant patterns river terraces provide important records of uplift which is essential for their formation and of landscape evolution their cyclic formation however almost invariably seems to have been a response to climatic fluctuation sequences in the european core area of igcp 449 which has the longest and most extensive research history have been used as templates for worldwide comparison there is evidence for a global acceleration of uplift at the time of and perhaps in response to the mid pleistocene revolution when climatic fluctuation switched to 100 kyr milankovitch cycles terraces formed prior to this generally consist of wide aggradational sheets that probably each represent formation over several 41 kyr cycles subsequently river valleys became more steeply entrenched and terraces formed in response to the stronger 100 kyr climatic forcing in many cases at approximately one per cycle this paper uses the new data resource to explore differences between records in different climate zones between sequences with variable numbers of middle late pleistocene terraces and between systems in which the all important incision event has occurred in different parts of climatic cycles key records discussed include european examples from the rhine thames somme dniester dnieper don volga and aguas from asia the gediz turkey and orontes syria from north america the south platte and colorado from south africa the vaal and sundays from australia the shoalhaven and from south america the amazon paraguay and tributaries of the colorado and negro

estimation of weathering rates and co2 drawdown based on solute load significance of granulites and gneisses dominated weathering in the kaveri river basin southern india abstract the solute load of the kaveri river south india and its tributaries draining diverse precambrian terrains during pre monsoon and monsoon periods was determined using average annual flow total drainage area and atmospheric input corrected major ion concentrations of these rivers chemical weathering rates annual fluxes of different ionic species to the ocean and co2 consumption rates were estimated bicarbonate is the most dominant ion 27 79 of anion budget in all the river samples collected during monsoon period followed by ca2 whereas in case of pre monsoon water samples na is the most dominant ion in meq l two approaches were adopted to estimate silicate and carbonate weathering rates in the drainage basin at musuri silicate weathering rate swr is 9 44 0 29 tons km2 a and carbonate weathering rate cwr is 1 46 0 16 tons km2 a more than 90 of the total ionic budget is derived from weathering of silicates in the kaveri basin co2 consumption rate in the basin for silicate weathering f co 2 sil is 3 83 0 12 105 mol km2 a upper limit which is comparable with the himalayan rivers at upper reaches for carbonate weathering f co 2 carb co2 consumption rate is 0 15 0 03 105 mol km2 a in the kaveri basin the lower limit of co2 consumption rate corrected for h2so4 during silicate and carbonate weathering is f co 2 sil is 3 24 1005 mol km2 a and f co 2 carb 0 13 105 mol km2 a respectively co2 sequestered due to silicate weathering in the kaveri basin is 25 41 0 82 109 mol a which represents 0 21 0 01 of global co2 drawdown this may be due to tropical climatic condition high rainfall during both sw and ne monsoon and predominance of silicate rocks in the kaveri basin

holocene evolution of the palar river southern india tracking history of migration provenance weathering and tectonics abstract this study examines the catchment and source morphodynamics of the palar river southern peninsular india here we applied a multidisciplinary approach remote sensing techniques lineament analysis geochemistry and ground penetration radar for a better understanding of its evolution during holocene times the major lineaments present in the palar river basin are showing the ne sw trend there are five major faults identified in the palar river basin with a transition zone where frequent smaller magnitude earthquakes have occurred the major fault f1 a strike slip fault occurs in the upper part of the palar river following the ne sw trend other major faults present are f2 and f3 with a transition zone where frequent minor and major tremors are documented fault f4 traverses in parallel to the cheyyar river a rapid change in the river course has resulted due to the movement along these strike slip faults f 5 nearer to the east coast indicates a passive tectonic activity regime the after effects of tectonic activity in the basin is further implicit from the gpr profile the sediments of active palar river are dominantly litharenite arkose wacke while the paleochannels are shale in composition weathering proxies such as cia pia elemental ratios along with a cn k plot indicate that a post depositional intense weathering due to climatic variability for all paleochannel sediments due to ongoing tectonic activity in the sources region along with subsequent aggradation and degradation in fluvial regimes the sediments of active palar river shows low to moderate weathering moreover the geochemical data also reveals that the sediments from the palar river and paleochannels are predominately from active continental and passive continental margins respectively moreover the major oxide trace elements and ree elements data indicate that palar river sediments are from a felsic source while paleochannels are from mafic source hence our study suggests that the catchment area of the palar river has been shifted to the south during the holocene period due to tectonic uplift subsequently the sediments of the paleochannels have undergone post depositional weathering due to ongoing tectonic activity and monsoonal changes in the region enhances rapid erosion in the catchment area results in the deposition of the huge thickness of sediments from the middle to lower reaches of active palar river

the sulu sea internal soliton experiment abstract we present the results of a comprehensive study of large amplitude internal solitons generated in the sulu sea in the philippines by intense tidal flow over a sharp bathymetric feature surface signatures of these waves have been observed in images from the dmsp landsat and nimbus 7 satellites and the space shuttle sir a synthetic aperture radar a two week experiment was conducted in the sulu sea in may 1980 from r v oceanograher during which a three mooring phased array of current meters and thermistors was implanted near the wave source and at 82 km and 200 km from the source seventeen soliton packets were observed whose properties underwent significant change as they propagated across the sea vertical profiles of density temperature and acoustic backscatter as well as radar and photographic surface signatures were obtained from the ship data from satellites moorings and the ship give unprecedented information on the spatial and temporal characteristics of solitary waves which ha

source and propagation of internal solitary waves in the northeastern south china sea 1 large amplitude internal solitary waves isws observed near dongsha island in the south china sea originate in tide topography interactions at luzon strait their arrival times at two moorings s7 at 117 17 e 21 37 n and y at 117 13 2 e 21 2 8 n are investigated with respect to model predicted barotropic tidal currents over lan yu ridge at luzon strait each isw packet can be associated with a westward tidal current peak the time lags between the isws and the barotropic tidal currents are 57 6 0 9 hours at s7 and 55 1 1 0 hours at y consistent with the mode one internal waves propagating nondispersively through the region s bathymetry and climatological stratification larger isws usually arrive earlier than smaller ones consistent with the theoretical relation between nonlinear wave speed and wave amplitude the observation that the isws are associated with westward tidal currents with without the presence of earlier eastward tidal currents suggests that they are generated by nonlinear steepening of internal tides rather than by the lee wave mechanism an idealized nonlinearization distance over which the isws are generated in internal tide troughs is estimated to be 260 40 km from luzon strait

large amplitude internal solitary waves observed in the northern south china sea properties and energetics abstractfive large amplitude internal solitary waves isws propagating westward on the upper continental slope in the northern south china sea were observed in may june 2011 with nearly full depth measurements of velocity temperature salinity and density as they shoaled at least three waves reached the convective breaking limit along wave current velocity exceeded the wave propagation speed c vertical overturns of 100 m were observed within the wave cores estimated turbulent kinetic energy was up to 1 5 10 4 w kg 1 in the cores and at the pycnocline the gradient richardson number was mostly 0 25 the maximum isw vertical displacement was 173 m 38 of the water depth the normalized maximum vertical displacement was 0 4 for three convective breaking isws in agreement with laboratory results for shoaling isws observed isws had greater available potential energy ape than kinetic energy ke for one of the largest observed isws the total wave energy per unit meter along the wave crest e