strong inland propagation of low frequency long waves in river estuaries tidal waves traveling into estuaries are modified by channel geometry and river flow the damping effect of river flow on incident astronomical tides is well documented whereas its impact on low frequency tides like msf and mm is poorly understood in this contribution we employ a numerical model to explore low frequency tidal behavior under varying river flow msf and mm are locally generated by frictional mechanisms inside an estuary and they are larger in amplitude far upstream in tidal rivers and persist landward of the point of tidal extinction increasing river flow nonlinearly modulates the longitudinal variations of msf and mm amplitudes this is dynamically explained by flow enhanced asymmetry in subtidal friction over the spring neap msf and perigee apogee mm cycles respectively estuaries act as frequency filters where low frequency waves decay at a smaller rate and propagate more inland than high frequency waves strong inland penetration of low frequency tides informs compound flood management

mineralogy and geochemistry of alluvium contaminated by metal mining in the rio tinto area southwest spain the rio tinto in sw spain drains cu and pyrite mines which have been in operation since at least the bronze age extensive metal mining especially from 1873 to 1954 has resulted in contamination of the rio tinto alluvium with as cu pb ag and zn x ray diffraction xrd wavelength dispersive x ray mapping scanning electron microscope petrography and x ray energy dispersive edx analysis has revealed that 4 major groups of contaminant metal and as bearing minerals including sulphides fe as oxides fe oxides hydroxides oxyhydroxides and fe oxyhydroxysulphates occur in the alluvium sulphide minerals including pyrite chalcopyrite arsenopyrite and sphalerite occur in alluvium near the mining areas iron hydroxides and oxyhydroxides such as goethite and possibly ferrihydrite occur in cements in both the mining areas and alluvium downstream and carry minor amounts of as cu and zn iron oxyhydroxysulphates including jarosite plumbojarosite and possibly schwertmannite are the most common minerals in alluvium downstream of the mining areas and are major hosts of cu pb zn and of as next to the fe as minerals this work and other field observations suggest that 1 the extreme acidity and elevated metal concentrations of the river water will probably be maintained for some time due to oxidation of pyrite and other sulphides in the alluvium and mine waste tips and from formation of secondary oxide and oxyhydroxysulphates 2 soluble fe oxyhydroxysulphates such as copiapite which form on the alluvium are a temporary store of contaminant metals but are dissolved during periods of high rainfall or flooding releasing contaminants to the aqueous system 3 relatively insoluble fe oxyhydroxysulphates and hydroxides such as jarosite and goethite may be the major long term store of alluvial contaminant metals and 4 raising river ph will probably cause precipitation of fe oxyhydroxides and oxides hydroxides oxyhydroxides and thus have a positive effect on water quality but this action may destabilise some of these contaminant metal bearing minerals releasing metals back to the aqueous system

long term change in tidal dynamics and its cause in the pearl river delta china abstract this paper focuses on identifying changes in the tidal range and the duration of the flood tide in the pearl river delta region china mann kendall test and regression methods are employed to verify the existence of trends in the annual tidal range and duration series from the 1950s to 2005 at 17 stations in the 3 major tributaries of the delta the research results indicate that generally there is an increasing trend in the tidal range and flood tide duration at most of the stations in the channel network moreover the more upstream the location of the station the more obvious the change in trend is and these increasing trends are all significant at the stations in the upper part of the delta specifically the tidal range at shilong station in the east river has increased abruptly since the middle of the 1980s such that the mean level of post 1990 data is approximately three times that for pre 1985 most stations near the mouth of the estuary show significant downward trends in the tidal range and flood tide duration results of the intersection point of the mann kendall test curves for these pearl river delta stations appear mostly in 1980s 1990s indicating that a noticeable change point occurs during this period human activities in the pearl river delta reached their peak during the 1980s among these large scale and long term sand excavation modified the hydrodynamic regime dramatically in a way that increased the water depth and lowered the level of the riverbed leading to an increased tidal prism and upstream movement of the tidal limit land reclamation is also likely to have had a relatively large effect on the tidal range and flood tide duration at stations near to the estuary mouth changes in other factors such as freshwater flow and sea level rise seem to be of relatively minor importance it is noteworthy that in a dry season the tidal dynamics are greatly enhanced and has resulted in strong saltwater intrusion into the estuary in recent years

spirit mars rover mission to the columbia hills gusev crater mission overview and selected results from the cumberland ridge to home plate this paper summarizes the spirit rover operations in the columbia hills of gusev crater from sols 513 to 1476 and provides an overview of selected findings that focus on synergistic use of the athena payload and comparisons to orbital data results include discovery of outcrops voltaire on husband hill that are interpreted to be altered impact melt deposits that incorporated local materials during emplacement evidence for extensive volcanic activity and aqueous alteration in the inner basin is also detailed including discovery and characterization of accretionary lapilli and formation of sulfate silica and hematite rich deposits use of spirit s data to understand the range of spectral signatures observed over the columbia hills by the mars reconnaissance orbiter s compact reconnaissance imaging spectrometer crism hyperspectral imager 0 4 4 m is summarized we show that crism spectra are controlled by the proportion of ferric rich dust to ferrous bearing igneous minerals exposed in ripples and other wind blown deposits the evidence for aqueous alteration derived from spirit s data is associated with outcrops that are too small to be detected from orbital observations or with materials exposed from the shallow subsurface during rover activities although orbital observations show many other locations on mars with evidence for minerals formed or altered in an aqueous environment spirit s data imply that the older crust of mars has been altered even more extensively than evident from orbital data this result greatly increases the potential that the surface or shallow subsurface was once a habitable regime

morphological evolution of the dee estuary eastern irish sea uk a tidal asymmetry approach abstract asymmetry in the tide unequal ebb and flood duration is a dominant factor in causing residual sediment transport and morphological changes in estuaries the evolution of estuarine morphology is a process of dynamic equilibrium in the short term while these features are ephemeral in the long term in this study we investigate the spatial distribution of tidal distortion and asymmetry in the dee estuary uk by 3 dimensional numerical modelling methods high resolution lidar surveys are used to underpin and explain our numerical modelling results in terms of basin hypsometry and areas of recent erosion and deposition harmonic analysis of the numerical modelling results showed that the shallower intertidal areas sand and mud banks were the most tidally asymmetric showing flood dominance the main navigation channels showed some ebb dominance but the tides here were relatively undistorted this overall flood dominance is likely to induce net sediment import to the dee which explains known historical morphological changes large scale accretion over the last two centuries and also recent morphological changes as seen from the lidar surveys which show predominantly net accretion between 2003 and 2006 hypsometrical analysis suggests the dee may be approaching equilibrium and that the flood dominance and sedimentation rate may therefore decrease in the future in an infilling estuary an increase in the area and elevation of tidal flats can eventually shift an estuary towards ebb dominance as shown by previous research and by idealised estuary modelling results presented in this study the large tidal amplitude to hydraulic depth ratio of the dee however suggests that the tidal flats would have to be very extensive indeed for this to occur

an introduction to wavelet transform tidal analysis methods continuous wavelet transforms cwts provide an approach to understanding the numerous tidal phenomena that deviate markedly from an assumed statistical stationarity or exact periodicity inherent in traditional tidal methods use of wavelets allows determination of the degree of non stationarity present in time series such as estuarine and shelf currents usually treated as stationary wavelets also provide a consistent analysis of tidal and non tidal variance a feature often essential for dynamical analyses of non stationary tides we summarize basic notions of the wavelet transform also known as a perfect reconstruction filter bank or a multire solution analysis contrast them with those of harmonic analysis and fourier transforms construct a continuous wavelet transform basis with a scale selection especially adapted to tidal problems describe possibilities for analysis of scalar and vector quantities define a criterion for knowledge of independence of process between adjoining scales and illustrate use of wavelet tools with several examples in contrast to the nearly periodic barotropic tide typical of coastal stations this paper analyses processes that are in part tidally driven but non stationary e g baroclinic tidal currents river tides continental shelf internal tides and some kinds of biological activity in the coastal ocean in all cases wavelet analysis provides a consistent linear analysis of tidal and non tidal variance and reveals features that harmonic analysis on a fourier transform approach could not elucidate

veneers rinds and fracture fills relatively late alteration of sedimentary rocks at meridiani planum mars veneers and thicker rinds that coat outcrop surfaces and partially cemented fracture fills formed perpendicular to bedding document relatively late stage alteration of ancient sedimentary rocks at meridiani planum mars the chemistry of submillimeter thick buff colored veneers reflects multiple processes at work since the establishment of the current plains surface veneer composition is dominated by the mixing of silicate rich dust and sulfate rich outcrop surface but it has also been influenced by mineral precipitation including nacl and possibly by limited physical or chemical weathering of sulfate minerals competing processes of chemical alteration perhaps mediated by thin films of water or water vapor beneath blanketing soils and sandblasting of exposed outcrop surfaces determine the current distribution of veneers dark toned rinds several millimeters thick reflect more extensive surface alteration but also indicate combined dust admixture halite precipitation and possible minor sulfate removal cemented fracture fills that are differentially resistant to erosion occur along the margins of linear fracture systems possibly related to impact these appear to reflect limited groundwater activity along the margins of fractures cementing mechanically introduced fill derived principally from outcrop rocks the limited thickness and spatial distribution of these three features suggest that aqueous activity has been rare and transient or has operated at exceedingly low rates during the protracted interval since outcropping meridiani strata were exposed on the plains surface

discovery of jarosite within the mawrth vallis region of mars implications for the geologic history of the region abstract analysis of visible to near infrared reflectance data from the mro crism hyperspectral imager has revealed the presence of an ovoid shaped landform approximately 3 by 5 km in size within the layered terrains surrounding the mawrth vallis outflow channel this feature has spectral absorption features consistent with the presence of the ferric sulfate mineral jarosite specifically a k bearing jarosite kfe3 so4 2 oh 6 terrestrial jarosite is formed through the oxidation of iron sulfides in acidic environments or from basaltic precursor minerals with the addition of sulfur previously identified phyllosilicates in the mawrth vallis layered terrains include a basal sequence of layers containing fe mg smectites and an upper set of layers of hydrated silica and aluminous phyllosilicates in terms of its fine scale morphology revealed by mro hirise imagery the jarosite bearing unit has fracture patterns very similar to that observed in fe mg smectite bearing layers but unlike that observed in the al bearing phyllosilicate unit the ovoid shaped landform is situated in an east west bowl shaped depression superposed on a north sloping surface spectra of the ovoid shaped jarosite bearing landform also display an anomalously high 600 nm shoulder which may be consistent with the presence of goethite and a 1 92 m absorption which could indicate the presence of ferrihydrite goethite jarosite and ferrihydrite can be co precipitated and or form through transformation of schwertmannite both processes generally occurring under low ph conditions ph 2 4 to date this location appears to be unique in the mawrth vallis region and could represent precipitation of jarosite in acidic sulfur rich ponded water during the waning stages of drying

hydrated silicate minerals on mars observed by the mars reconnaissance orbiter crism instrument phyllosilicates a class of hydrous mineral first definitively identified on mars by the omega observatoire pour la mineralogie l eau les glaces et l activitie instrument preserve a record of the interaction of water with rocks on mars global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy fe mg and al smectite clays this was interpreted to indicate that phyllosilicate formation occurred during the noachian the earliest geological era of mars and that the conditions necessary for phyllosilicate formation moderate to high ph and high water activity were specific to surface environments during the earliest era of mars s history here we report results from the compact reconnaissance imaging spectrometer for mars crism of phyllosilicate rich regions we expand the diversity of phyllosilicate mineralogy with the identification of kaolinite chlorite and illite or muscovite and a new class of hydrated silicate hydrated silica we observe diverse fe mg oh phyllosilicates and find that smectites such as nontronite and saponite are the most common but chlorites are also present in some locations stratigraphic relationships in the nili fossae region show olivine rich materials overlying phyllosilicate bearing units indicating the cessation of aqueous alteration before emplacement of the olivine bearing unit hundreds of detections of fe mg phyllosilicate in rims ejecta and central peaks of craters in the southern highland noachian cratered terrain indicate excavation of altered crust from depth we also find phyllosilicate in sedimentary deposits clearly laid by water these results point to a rich diversity of noachian environments conducive to habitability

geochemistry of shales from the archean 3 0 ga buhwa greenstone belt zimbabwe implications for provenance and source area weathering abstract phyllites from the archean 3 0 ga buhwa greenstone belt zimbabwe were deposited on a stable cratonic platform analyses of the phyllites generally define a single geochemical group based on major and trace element abundances the phyllites are strongly depleted in cao na2o and sr with respect to average archean upper crust by contrast k2o ba and rb are enriched several times relative to average archean upper crust reflecting basin scale k metasomatism transition metals are somewhat depleted whereas high field strength elements are typically enriched relative to average archean upper crust samples generally have fractionated lree patterns average cen smn 2 4 with small negative eu anomalies average eu eu 0 78 and generally flat hrees average gdn ybn 1 3 such geochemical characteristics suggest that the source dominantly consisted of tonalite with less common occurrences mafic volcanic rocks and granite mixing calculations which massbalance the rees and th sc suggest 70 tonalite 15 mafic volcanic rocks and 15 granite as possible proportions for the source of the phyllites a nearby early archean 3 5 ga continental nucleus preserves similar lithologies and is the probable source intense chemical weathering of the source terrane is indicated by premetasomatized chemical index of alteration values of 95 100 nearly complete depletion of cao and na2o and high al2o3 na2o ratios fine grained sediments of comparable age and presumed tectonic setting elsewhere in southern africa show similar geochemical characteristics implying that source area compositions and weathering intensities were similar these mature platformal deposits suggest a tectonically stable environment where intense chemical weathering took place at 3 0 ga across southern africa

flood ebb tidal asymmetry in a shallow sandy estuary and the impact on net sand transport flood ebb tidal dominance plays a pivotal role in estuarine sediment transport the dyfi estuary mid wales uk is used as a case study together with an idealized trumpet shaped estuary morphology to illustrate key processes giving rise to flood ebb dominance observations made in the main entrance channel to the dyfi indicate that the system is presently ebb dominant with regard to both the relatively long duration of the ebb tide and also the faster ebb velocities predictions made across the mouth of the estuary using the telemac modelling system suggest further that the net sand transport presently occurs out of the estuary in contrast due to the varying distribution of channels and flats within the estuary the tidal flow in the upper estuary is flood asymmetric and here the net transport is up estuary flood versus ebb dominance is shown to be attributable to the relative extent of the channels and sandflats in relation to the mean water level an attempt is made to develop a simple metric to determine present day transport pathways within an estuary in response to its cross channel flow asymmetries

temporal and spatial variability of tidal fluvial dynamics in the st lawrence fluvial estuary an application of nonstationary tidal harmonic analysis predicting tides in upstream reaches of rivers is a challenge because tides are highly nonlinear and nonstationary and accurate short time predictions of river flow are hard to obtain in the st lawrence fluvial estuary tide forecasts are produced using a one dimensional model one d forced downstream with harmonic constituents and upstream with daily discharges using 30 day flow forecasts from lake ontario and the ottawa river although this operational forecast system serves its purpose of predicting water levels information about nonstationary tidal fluvial processes that can be gained from it is limited particularly the temporal changes in mean water level and tidal properties i e constituent amplitudes and phases which are function of river flow and ocean tidal range in this paper a harmonic model adapted to nonstationary tides ns tide was applied to the st lawrence fluvial estuary where the time varying external forcing is directly built into the tidal basis functions model coefficients from 13 analysis stations were spatially interpolated to allow tide predictions at arbitrary locations as well as to provide insights into the spatiotemporal evolution of tides model hindcasts showed substantial improvements compared to classical harmonic analyses at upstream stations the model was further validated by comparison with one d predictions at a total of 32 stations the slightly lower accuracy obtained with ns tide is compensated by model simplicity efficiency and capacity to represent stage and tidal variations in a very compact way and thus represents a new means for understanding tidal rivers

volcanic source for fixed nitrogen in the early earth s atmosphere hot volcanic vents promote the thermal fixation of atmospheric n2 into biologically available forms the importance of this process for the global nitrogen cycle is poorly understood at masaya volcano nicaragua no and no2 are intimately associated with volcanic aerosol such that nox levels reach as much as an order of magnitude above local background in plume hno3 concentrations are elevated above background to an even greater extent 50 mmol m 23 we estimate the production efficiency of fixed nitrogen at hot vents to be 3 3 10 28 mol j 21 implying present day global production of 10 9 mol of fixed n per year although conversion efficiency would have been lower in a preoxygenated atmosphere we suggest that subaerial volcanoes potentially constituted an important source of fixed nitrogen in the early earth producing as much as 10 11 mol yr 21 of fixed n during major episodes of volcanism these fluxes are comparable to estimated nitrogen fixation rates in the prebiotic earth from other major sources such as bolide impacts and thunderstorm and volcanic lightning

hydrothermal jarosite and hematite in a pyroxene hosted melt inclusion in martian meteorite miller range mil 03346 implications for magmatic hydrothermal fluids on mars low temperature aqueous processes have been implicated in the generation of jarosite and hematite on the martian surface but little is known regarding the role that high temperature magmatic fluids may have played in producing similar assemblages on mars we have identified jarosite and hematite in a clinopyroxene hosted melt inclusion in martian meteorite mil 03346 that shows evidence of having been hydrothermally precipitated in addition to jarosite and hematite the melt inclusion contains titanomagnetite pyrrhotite potassic chlorohastingsite an iron rich silicate glass and possibly goethite these phases were identified and characterized using scanning electron microscopy sem con focal raman spectroscopy and electron probe microanalysis epma based on observed textural relationships and the compositions of the hosted phases we report that the jarosite bearing melt inclusion in mil 03346 has recorded a fluid rich history that began in the magmatic stage and continued to low temperatures this history begins at entrapment of a volatile rich silicate melt that likely reached fluid saturation after only minor crystallization within the melt inclusion this fluid rich in chlorine reacted with surrounding silicate material to produce the potassicchlorohastingsite as cooling proceeded the liquid phase eventually became more oxidized and reacted with the pyrrhotite sulfide oxidation resulted in so4 2 formation and concomitant acid production setting the stage for jarosite formation once the fluid cooled beyond the upper thermal stability of jarosite 200 c as the fluid cooled below 200 c jarosite continued to precipitate with hematite and or goethite until equilibrium was established or reactions became kinetically unfavorable this work suggests an additional jarosite hematite formation pathway on mars one that may be important wherever magmatic hydrothermal fluids come into contact with primary sulfide grains at the martian surface or subsurface moreover hydrothermal fluids rich in chlorine sulfur and iron are important for ore forming processes on earth and their indirect identification on mars may have important implications for ore formation on mars

tidal asymmetry in estuaries with mixed semidiurnal diurnal tides 1 tidal asymmetry in estuaries with mixed mainly semidiurnal tides arises from both the interaction of principal tides and the higher harmonics generated by distortions within the estuary the duration asymmetry in rise and fall of water level caused by principal tides on the west coast of the continental united states is ebb dominant and so the tide entering estuaries is also ebb dominant prior to any internal distortions within the estuary the interaction of higher harmonics with principal constituents either augments or cancels the duration asymmetry in the principal tides in estuaries where tidal elevation and velocity phase are near quadrature 90 out of phase the duration asymmetry in tidal elevation leads to asymmetries in tidal current magnitude asymmetry can be conveniently quantified in terms of the sample skewness 1 the normalized third sample moment about the mean an analytic approximation to the skewness shows that traditional metrics of asymmetry namely the ratio of constituent amplitudes and the relative constituent phase difference arise from calculating the third sample moment observations from three california estuaries of different morphologies are presented as an illustration of how skewness can be used to quantify asymmetry in real systems as in semidiurnal systems morphology is a good predictor of whether higher harmonics engender ebb dominance or flood dominance however asymmetry imposed by principal tides at the mouth must first be overcome and so there is a spatial evolution in the total asymmetry quantifying observations via skewness should be considered in addition to traditional metrics in estuaries with mixed tides

rio tinto sedimentary mineral assemblages a terrestrial perspective that suggests some formation pathways of phyllosilicates on mars abstract the presence of extensive phyllosilicate deposits from the early noachian of mars are often interpreted as having formed from neutral to subalkaline solutions in this paper we examine the rio tinto fluvial basin an early mars analog that hosts clay production and sedimentation along the entire course of the river at rio tinto phyllosilicate minerals including clays and micas are sourced by volcanosedimentary bedrock of rhyolitic and andesitic composition affected by carboniferous hydrothermal alteration pleistocene to modern acidic weathering of those materials chemically altered the volcanic and sedimentary materials to k na clay montmorillonite smectites kaolinite assemblages in paleosoils and fractures while physical weathering degrades phyllosilicates more resistant to acidic attack during the wet season phyllosilicates are eroded transported and deposited from both acidic headwaters and neutral tributaries during the dry season sulfates and nanophase oxyhydroxides co precipitate late summer storms that cause fast flooding events mix illite quartz feldspars iron oxides and other minerals in fluvial deposits where these minerals are stabilized and aggrade until the following wet season as a result chemical precipitates primary phyllosilicates and secondary clays form mineral admixtures that explain the compositional diversity of the fluvial deposits these deposits reveal the persistence of smectites whose occurrence is explained given that the reaction kinetics under acidic conditions of degradation is lowered by seasonal discharges of the river the longevity of phyllosilicate minerals within fluvial deposits depends on climatic and geochemical conditions and processes which are in turn are correlated to temperature persistence of water hydrological cycling hydrogeochemistry and composition of the source materials in the basement these parameters are universal and have to be characterized in order to understand the distribution of mineral composition on any planetary surface including mars

nodal variations and long term changes in the main tides on the coasts of china the long term changes in the main tidal constituents o1 k1 m2 n2 and s2 along the coasts of china and in adjacent seas are investigated based on 17 tide gauge records covering the period 1954 2012 the observed 18 61 year nodal modulations of the diurnal constituents o1 and k1 are in agreement with the equilibrium tidal theory except in the south china sea the observed modulations of the m2 and n2 amplitudes are smaller than theoretically predicted at the northern stations and larger at the southern stations the discrepancies between the theoretically predicted nodal variations and the observations are discussed the 8 85 year perigean cycle is identifiable in the n2 parameters at most stations except those in the south china sea the radiational component of s2 contributes on average 16 of the observed s2 except in the gulf of tonkin on the south coast where it accounts for up to 65 we confirmed the existence of nodal modulation in s2 which is stronger on the north coast the semidiurnal tidal parameters show significant secular trends in the bohai and yellow seas on the north coast and in the taiwan strait the largest increase is found for m2 for which the amplitude increases by 4 7 mm yr in the yellow sea the potential causes for the linear trends in tidal constants are discussed

unravelling the causes of tidal asymmetry in deltas abstract tidal asymmetry in deltas is caused by both the intrinsic asymmetry resulting from the combination of astronomical tides and by nonlinear tidal interactions that occur in shallow water the relative importance of these sources of tidal asymmetry in delta channel networks have remained poorly studied partly due to the limitations of classical harmonic analysis ha in hindcasting nonstationary tides the pearl river delta prd is a multichannel system with rapidly changing bathymetry subject to severe human interventions this work applies a nonstationary harmonic model ns tide to hydrological data from 15 stations in the prd spanning the period 1961 2012 the spatiotemporal variation of multiple sources of tidal asymmetry is quantified by a skewness metric revealing how similar or dissimilar the development of alternative sources of tidal asymmetry develop in the delta subject to study a relative sensitivity coefficient rsc is introduced to decompose the contribution of tidal amplitude variations to multiple tidal asymmetries analytical results show the development of tides becoming gradually more asymmetric as they propagate into delta channel networks and how this depends on the river flow variation in the orientation of tidal asymmetries induced by different combinations of tidal constituents leads to a complex pattern of the overall tidal asymmetry in the prd our results show that tidal asymmetry in deltas can be significantly dependent on the river flow

illite and hydrocarbon exploration illite is a general term for the dioctahedral mica like clay mineral common in sedimentary rocks especially shales illite is of interest to the petroleum industry because it can provide a k ar isotope date that constrains the timing of basin heating events it is critical to establish that hydrocarbon formation and migration occurred after the formation of the trap anticline etc that is to hold the oil illite also may precipitate in the pores of sandstone reservoirs impeding fluid flow illite in shales is a mixture of detrital mica and its weathering products with diagenetic illite formed by reaction with pore fluids during burial k ar ages are apparent ages of mixtures of detrital and diagenetic end members and what we need are the ages of the end members themselves this paper describes a methodology based on mineralogy and crystallography for interpreting the k ar ages from illites in sedimentary rocks and for estimating the ages of the end members

tides and long term modulations in the caribbean sea the tidal signal and its long term variation in the caribbean sea is analyzed on the basis of hourly records from thirteen tide gauges five of which span more than 20 years the seven larger tidal constituents are studied namely the fortnightly term mf diurnal k1 o1 and p1 and semidiurnal m2 s2 and n2 the 18 61 year nodal modulation is clearly identifiable in almost all the examined constituents of lunar origin however its signal in m2 is less clear while it is almost imperceptible in n2 where the 8 85 year cycle caused by the eccentricity of the moon s orbit and the orientation of its major axis variation dominates the long term variability the effect of the nodal variation in the amplitude and phase lag of the various tidal constituents is in agreement within the 95 error limits with the theoretical gravitational estimate with the exception of the 8 85 year cycle in n2 where larger values are found overall in the caribbean the net effect of the low frequency cycles can change the maximum tidal range from 16 5 to 23 5 in a nodal cycle although the caribbean is a micro tidal environment this still results in changes of the range of up to 8 4 cm significant spatially coherent trends are found for the amplitude of s2 2 3 to 8 8 mm cy

double peak flood current asymmetry in a shallow water constituent dominated embayment with a macro tidal flat 1 tide and tidal current distortions were examined in hampyung embayment a shallow semidiurnal tide dominated bay with large tidal flats via in situ monitoring harmonic analyses reveal that the shallow water constituents of the tides and tidal currents are strong in this restricted setting relative to on the open coast in particular the amplitudes of the shallow water currents constituents m4 ms4 m6 2ms6 are three times greater than those of the diurnal constituents k1 o1 the quarter diurnal m4 ms4 and sexta diurnal m6 2ms6 current amplitudes account for 35 and 17 of the semi diurnal current m2 s2 amplitudes which account for 42 of total amplitude the ms4 current amplitude is as important as that of the m4 amplitude in the middle of the bay such strong generation of shallow water velocity constituents induced by non linear processes leads to an ebb dominated tidal regime with double flood current velocity peaks

formation of jarosite bearing deposits through aqueous oxidation of pyrite at meridiani planum mars 1 the discovery of sulfate rich layered deposits with hematite spherules at the landing site of the opportunity rover is consistent with mineral deposition in an aqueous environment we evaluate conditions responsible for the formation of a jarosite goethite gypsum assemblage with speciation calculations the results show that the assemblage could have precipitated from acidic solutions formed through near surface aqueous oxidation of pyrite our hypothesis is that regional heating in the meridiani planum caused a release of sulfide rich hydrothermal waters leading to formation of pyrite rich regional deposits in a depression aqueous oxidation of these deposits by atmospheric o2 created an acidic environment that allowed formation of sulfates and goethite partial neutralization of the solution caused further goethite precipitation and conversion of jarosite to goethite leading to formation of goethite concretions subsequent dehydration of goethite to coarse grained hematite would also have been facilitated by regional heating

dating incipient metamorphism using 40 ar 39 ar geochronology and xrd modeling a case study from the swiss alps six samples of a single carbonate rich unit of the swiss prealpes progressively metamorphosed from diagenesis to deep anchizone yield 40ar 39ar spectra with variably developed staircase patterns consistent with mixtures of detrital mica and neocrystallized mixed layer illite smectite the lowest temperature heating steps for different size fractions 2 6 m and 6 20 m converge to 40 ma providing an imprecise maximum age of regional metamorphism a method is described for distinguishing and quantifying the amount of pre existing detrital mica versus neoformed illite layer in the illite smectite formed during tertiary alpine metamorphism by comparison of x ray diffraction patterns with newmod simulations in the least metamorphosed samples the illite smectite contains 65 neoformed illite and this illite accounts for approximately 17 of all dioctahedral phyllosilicate minerals in the rock e g detrital mica and illite smectite in contrast the illite smectite from the more strongly metamorphosed samples contains 97 neoformed illite which accounts for 70 to 90 of all dioctahedral phyllosilicate minerals phyllosilicate morphologies viewed by scanning electron microscopy are consistent with these estimates a process of dissolution reprecipitation is inferred as a mechanism for the growth of the neoformed phyllosilicates a plot of neoformed illite content versus 40ar 39ar total fusion age yields a near linear curve with an extrapolated age of 27 ma for 100 neoformed dioctahedral phyllosilicates this age is interpreted as the time of incipient metamorphism and is consistent with independent biostratigraphic constraints model 40ar 39ar age spectra constructed with the xrd simulation results correspond well to the experimental data and illustrate the changes in degassing properties of progressively metamorphosed mixtures of detrital mica and neoformed illite

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

opaline silica in young deposits on mars high spatial and spectral resolution reflectance data acquired by the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism instrument reveal the presence of h 2o and sioh bearing phases on the martian surface the spectra are most consistent with opaline silica and glass altered to various degrees confirming predictions based on geochernicall experiments and models that amorphous silica should be a common weathering product of the basaltic martian crust these materials are associated with hydrated fe sulfates including h 3o bearing jarosite and are found in finely stratified deposits exposed on the floor of and on the plains surrounding the valles marineris canyon system stratigraphic relationships place the formation age of these deposits in the late hesperian or possibly the amazonian implying that aqueous alteration continued to be an important and regionally extensive process on mars during that time

study of current dynamics of soils from a podzol oxisol sequence in tahiti french polynesia using the test mineral technique abstract the current soil dynamics of a podzol oxisol climosequence located in tahiti on basaltic and pyroclastic parent rocks has been investigated using the test mineral technique the test mineral a vermiculite with a high exchange capacity 161 meq 100 g was placed in recoverable bags in the a and b horizons of three members of the sequence for periods of 1 to 3 5 years changes in the chemistry and mineralogy enabling complexing acid environments to be distinguished from non complexing were determined following the in situ reaction with natural soil leachates a set of leachates from the same horizons were collected and chemically analysed at the end of 3 5 years the results indicate that the current acid environment is only weakly complexing this suggests that the podzolisation processes which led to the development of a unique a2 horizon containing gibbsite anatase and rutile and a placic horizon in the upper podzol member of the sequence is no longer operating

a mineralogical archive of the biogeochemical sulfur cycle preserved in the subsurface of the rio tinto system the search for extinct and extant life on mars is based on the study of biosignatures that could be preserved under mars like extreme conditions that are replicated in different terrestrial analog

orbital evidence for clay and acidic sulfate assemblages on mars based on mineralogical analogs from rio tinto spain outcrops of hydrated minerals are widespread across the surface of mars with clay minerals and sulfates being commonly identified phases orbitally based reflectance spectra are often used to classify these hydrated components in terms of a single mineralogy although most surfaces likely contain multiple minerals that have the potential to record local geochemical conditions and processes reflectance spectra for previously identified deposits in ius and melas chasma within the valles marineris mars exhibit an enigmatic feature with two distinct absorptions between 2 2 and 2 3 m this spectral doublet feature is proposed to result from a mixture of hydrated minerals although the identity of the minerals has remained ambiguous here we demonstrate that similar spectral doublet features are observed in airborne field and laboratory reflectance spectra of rock and sediment samples from rio tinto spain combined visible near infrared reflectance spectra and x ray diffraction measurements of these samples reveal that the doublet feature arises from a mixture of al phyllosilicate illite or muscovite and jarosite analyses of orbital data from the compact reconnaissance imaging spectrometer for mars crism shows that the martian spectral equivalents are also consistent with mixtures of al phyllosilicates and jarosite where the al phyllosilicate may also include kaolinite and or halloysite a case study for a region within ius chasma demonstrates that the relative proportions of the al phyllosilicate s and jarosite vary within one stratigraphic unit as well as between stratigraphic units the former observation suggests that the jarosite may be a diagenetic authigenic product and thus indicative of local ph and redox conditions whereas the latter observation may be consistent with variations in sediment flux and or fluid chemistry during sediment deposition

propagation of tidal waves up in yangtze estuary during the dry season tide is one of the most important hydrodynamic driving forces and has unique features in the yangtze estuary ye due to the complex geometry of third order bifurcations and four outlets this paper characterizes the tidal oscillations tidal dampening tidal asymmetry and tidal wave propagation which provides insights into the response of the estuary to tides during the dry season the structural components of tidal oscillations are initially attained by tidal analysis the increasingly richer spectrum inside the estuary shows an energy transfer corresponding to the generation and development of nonlinear overtides and compound tides a 2 d numerical model is further set up to reproduce tidal dynamics in the estuary the results show that the estuary is a strongly dissipative estuary with a strong nonlinear phenomenon three amplifications are presented in the evolution process of tidal ranges due to the channel convergence tidal asymmetry is spatiotemporally characterized by the m4 m2 amplitude ratio the 2m2 m4 phase difference and the flood ebb duration asymmetry parameter and the estuary tends to be flood dominant there exists mimic standing waves with the phase difference of the horizontal and vertical tide close to 90 when tidal wave propagates into the estuary especially during the neap tide in addition the differences in tidal distortion tidal ranges and tidal waves along the two routes in the south branch s b suggest the branched system behaves differently from a single system

fossilization potential of iron bearing minerals in acidic environments of rio tinto spain implications for mars exploration abstract acidic waters of the rio tinto southwestern spain evaporate seasonally precipitating a variety of iron sulfide and oxide minerals schwertmannite and nanophase goethite form thin laminae on biological and detrital grain surfaces replicating among other things the morphologies of insect cuticle plant tissues fungi algae and bacteria intergrain cements also incorporate bacterial cells and filaments other sulfate minerals precipitated in rio tinto environments are transient and contribute little to short term preservation because the rio tinto has been cutting its current valley for several million years terrace deposits provide a window on longer term fossil preservation early and later diagenesis are recorded in terrace deposits formed about one thousand and two million years ago respectively the sedimentary structures and mineralogies of these deposits suggest that they formed under physical and chemical conditions comparable to those of modern rio tinto sediments the terrace deposits show quantitative loss of sulfate minerals increasing crystallinity of goethite and in the older terrace replacement of goethite by hematite fossils formed originally by schwertmannite and nanophase goethite replication persist through diagenesis preserving a long term record of local biological diversity fossil preservation by iron oxides in the acidic environment of rio tinto suggests that if life was present when sedimentary rocks formed at meridiani planum mars precipitated minerals could record their presence

the triassic and jurassic paleogeography and evolution of the qinghai xizang tibet plateau the kunlun qilian and qinling mountains already existed in embryonic form as coastal ranges in triassic times marine conditions predominated to the south the southern coastline is demarcated by the northern margin of the tertiary siwalik sediments the paleo landmass of longmenshan sichuan yunnan separated this sea from that of southwest china by jurassic times the coastline of the eurasian continent within what is now china had already moved southwards to a line along the kunlun and hengduan mountains mainly on the basis of differences between continental and oceanic crust several different seas can be distinguished the himalayan lhasa qiangtang hengduan and triangle seas together with the qaidam peninsula and xining bay triassic and jurassic transgressions and regressions of these seas are discussed in detail during carboniferous and permian times the lhasa and himalayan seas were joined together with the main gondwana plate to the south in triassic times when the india pakistan subconti

exploring the impacts of multiple tidal constituents and varying river flow on long term large scale estuarine morphodynamics by means of a 1 d model tidal asymmetry is an important mechanism generating tidal residual sediment transport trst in tidal environments so far it is known that a number of tidal interactions e g m2 m4 and m2 o1 k1 can induce tidal asymmetry and associated trst however their variability and morphodynamic impacts are insufficiently explored inspired by the river and tidal forcing conditions in the yangtze river estuary we explore the morphodynamic development of a 560 km long estuary under the boundary forcing conditions of varyingly combined tidal constituents and river discharges using a schematized 1 d morphodynamic model for long term millennial simulations we then employ an analytical scheme which integrates sediment transport as a function of flow velocities to decompose the contribution of different tidal interactions on trst and to explain how the river and tidal interactions control trst and associated morphodynamics model results display varying equilibrium bed profiles analytical results suggest that 1 a series of tidal interactions creates multiple tidal asymmetries and associated trst 2 river flow modulates tidal asymmetry nonlinearly in space and 3 more tidal constituents at the sea boundary persistently enhance the seaward trst through river tide interactions it is the combined effects of multiple tidal asymmetries and river tide interactions that determine the net trst and consequent morphodynamic development it thus suggests that tidal harmonics of significant amplitudes need to be considered properly as boundary conditions for long term large scale morphodynamic modeling

geological record of an acidic environment driven by iron hydrochemistry the tinto river system 1 the existence of possible hematitic strata on the surface of mars demands a search for terrestrial analogues formed in unusual environments this will help us to recognize and interpret environmental and perhaps biological signatures preserved in mars hematites such an analogue would allow us to establish valid reference systems based on geomicrobial and biogeochemical signatures two different aspects place the tinto river inside the boundaries of a natural extreme system its high level of biological diversity and the presence of fluvial rocks formed in the same acidic conditions as in the modern system which could predate the tertiary study of both the modern system and the ancient system is necessary to understand the formation of biosignatures a chemolithotrophic community that biooxidizes the iberian pyritic belt acidifying water ph between 0 9 and 3 0 and favoring high concentrations of ferric iron in solution up to 20 g l 1 maintains this iron driven system in spite of these extreme conditions high microbial diversity was found its acidic bacteria archaea and eukarya constitute a complex community supported by algal biomass in highly stable hydrochemical conditions which are achieved through iron buffering the ph is maintained at constant low levels even at very high water dilution in these conditions iron minerals as oxyhydroxides hydroxides and sulfates are formed the modern and recent parageneses contrast with the ancient tinto river terrace mineral associations which show dehydrated and desulfated iron oxides if this dehydration process is considered these tinto river ironstones may be a key for knowing some aquatic habitats which may have hosted a part of the early mars biosphere

meta gabbro weathering in the georgia piedmont usa implications for global silicate weathering rates abstract the mineral assemblages in a vertical weathering profile developed over a meta gabbro terrain were studied for their stoichiometry and relative abundances the site is located in the piedmont province in the southeast portion of the appalachians orogenic belt in a forested residual landscape and a temperate climate the soil is classified as a fine mixed thermic ultic hapludalf and defined by distinct a b and c horizons with thicknesses of 17 62 and 250 cm respectively the primary mineral assemblage consists of 44 wt andesine 40 hornblende 6 quartz 4 biotite 3 ilmenite titanomagntite rutile sphene grains and 3 epidote quantitative xrd detailed xrd clay mineralogy and thin section petrography revealed the incipient breakdown of the primary minerals to vermiculite after biotite oxidation randomly ordered mixed layer mica vermiculite smectite as grain coatings kaolin group minerals after mafic silicate dissolution goethite and hematite vermiculite after biotite expandable clay coatings and all the primary minerals with exception to quartz are dissolved away from the a horizon hydroxy interlayered vermiculite and minor amounts of gibbsite occur as tertiary phases in the a horizon using mineral stoichiometries and average abundances for the parent rock and c b and a horizon estimates of primary mineral mass loss were determined the bicarbonate to silica ratio expected from the mineral loss reactions is 6 times higher than the ratio observed in average groundwater of the georgia piedmont this suggests that although weathering of mafic terrains is important to the long term process of transferring co 2 to the oceans the present day contribution of silicate weathering in temperate climates may be more largely influenced by the weathering of felsic terrain

evidence for montmorillonite or its compositional equivalent in columbia hills mars 1 during its exploration of the columbia hills the mars exploration rover spirit encountered several similar samples that are distinctly different from martian meteorites and known gusev crater soils rocks and sediments occurring in a variety of contexts and locations these independence class samples are rough textured iron poor equivalent feo 4 wt have high al si ratios and often contain unexpectedly high concentrations of one or more minor or trace elements including cr ni cu sr and y apart from accessory minerals the major component common to these samples has a compositional profile of major and minor elements which is similar to the smectite montmorillonite implicating this mineral or its compositional equivalent infrared thermal emission spectra do not indicate the presence of crystalline smectite one of these samples was found spatially associated with a ferric sulfate enriched soil horizon possibly indicating a genetic relationship between these disparate types of materials compared to the nearby wishstone and watchtower class rocks major aqueous alteration involving mineral dissolution and mobilization with consequent depletions of certain elements is implied for this setting and may be undetectable by remote sensing from orbit because of the small scale of the occurrences and obscuration by mantling with soil and dust

tidal velocity asymmetries and bedload transport in shallow embayments abstract tidal circulation can cause a net transport of sediment when the tidal velocity is asymmetric about a zero mean flood or ebb dominant and the sediment transport rate is related nonlinearly to velocity the relationship between tidal elevation and velocity is elucidated here to permit determination from tide gauge data and sediment transport relations whether tidal asymmetry needs to be considered as a mechanism for net sediment transport in the embayment of interest a relationship between elevation and velocity in a shallow water nonlinear system is derived through the continuity equation and shown to be significantly different than the linear relation finite difference numerical solutions of the one dimensional shallow water nonlinear equations are compared to the continuity relation and are in agreement especially toward the landward end of the channel tide gauge data collected at the landward end of the embayment are most useful for predicting velocity asymmetries throughout a major portion of the embayment channel the ratio of flood to ebb bedload transport and its relation to an asymmetric tidal elevation has been determined for both the linear relation between elevation and velocity and the nonlinear relation results show that the ratio of flood to ebb bedload transport as calculated from the nonlinear relation between elevation and velocity is similar to the flood to ebb ratio calculated from the linear relation because of offsetting effects

flow asymmetry associated with astronomical tides implications for the residual transport of sediment 1 tidal current asymmetry is usually associated to nonlinear tidal interactions in shallow water generating compound tides and overtides the present paper demonstrates that tidal asymmetry is not only caused by nonlinear tidal interaction but is also generated by astronomical tides in absence of shallow water effects in particular the k1 o1 and m2 constituents give an asymmetrical periodic flow pattern with the largest peak velocities persistently in the same direction a theoretical explanation for this phenomenon is presented and an inventory is made of other subordinate constituents that may contribute to repetitive asymmetric flow patterns tidal current asymmetry may induce residual transport of sediment analytical expressions are derived which quantify the residual transport of sediment due to the k1 o1 and m2 tides as a function of the phases and amplitudes of these constituents and the time lag between variation in suspended sediment transport and flow velocity the residual transport induced by the k1 o1 and m2 tides is compared to the residual transport due to the asymmetry associated with the m2 and m4 tides the former mechanism is particularly relevant in diurnal or mixed mainly diurnal tidal regimes where the k1 and o1 tides are dominant

the rio tinto basin spain mineralogy sedimentary geobiology and implications for interpretation of outcrop rocks at meridiani planum mars abstract exploration by the nasa rover opportunity has revealed sulfate and hematite rich sedimentary rocks exposed in craters and other surface features of meridiani planum mars modern holocene and plio pleistocene deposits of the rio tinto southwestern spain provide at least a partial environmental analog to meridiani planum rocks facilitating our understanding of meridiani mineral precipitation and diagenesis while informing considerations of martian astrobiology oxidation thought to be biologically mediated of pyritic ore bodies by groundwaters in the source area of the rio tinto generates headwaters enriched in sulfuric acid and ferric iron seasonal evaporation of river water drives precipitation of hydronium jarosite and schwertmannite while mg al fe3 copiapite coquimbite gypsum and other sulfate minerals precipitate nearby as efflorescences where locally variable source waters are brought to the surface by capillary action during the wet season hydrolysis of sulfate salts results in the precipitation of nanophase goethite holocene and plio pleistocene terraces show increasing goethite crystallinity and then replacement of goethite with hematite through time hematite in meridiani spherules also formed during diagenesis although whether these replaced precursor goethite or precipitated directly from groundwaters is not known the retention of jarosite and other soluble sulfate salts suggests that water limited the diagenesis of meridiani rocks diverse prokaryotic and eukaryotic microorganisms inhabit acidic and seasonally dry rio tinto environments organic matter does not persist in rio tinto sediments but biosignatures imparted to sedimentary rocks as macroscopic textures of coated microbial streamers surface blisters formed by biogenic gas and microfossils preserved as casts and molds in iron oxides help to shape strategies for astrobiological investigation of meridiani outcrops

comment on on the role of diurnal tides in contributing to asymmetries in tidal probability distribution functions in areas of predominantly semi diurnal tide by p l woodworth d l blackman d t pugh and j m vassie estuarine coastal and shelf science 64 2005 235 240 abstract the present paper comments on a recent publication by woodworth et al woodworth p l blackman d l pugh d t vassie j m 2005 on the role of diurnal tides in contributing to asymmetries in tidal probability distribution functions in areas of predominantly semi diurnal tide estuarine coastal and shelf science 64 2 3 235 240 it is shown how tidal asymmetries associated with astronomical tides can be accounted for in an extreme sea level analysis despite the difficulty of deriving probability distribution functions if a large number of tidal constituents are considered the use of the term spring neap cycle in a diurnal tidal regime is discussed

carbonate precipitation under bulk acidic conditions as a potential biosignature for searching life on mars recent observations of carbonate minerals in ancient martian rocks have been interpreted as evidence for the former presence of circumneutral solutions optimal for carbonate precipitation sampling from surface and subsurface regions of the low ph system of rio tinto has shown unexpectedly that carbonates can form under diverse macroscopic physicochemical conditions ranging from very low to neutral ph 1 5 7 0 a multi technique approach demonstrates that carbonate minerals are closely associated with microbial activity carbonates occur in the form of micron size carbonate precipitates under bacterial biofilms mineralization of subsurface colonies and possible biogenic microstructures including globules platelets and dumbbell morphologies we propose that carbonate precipitation in the low ph environment of rio tinto is a process enabled by microbially mediated neutralization driven by the reduction of ferric iron coupled to the oxidation of biomolecules in microbially maintained circumneutral oases where the local ph at the scale of cells or cell colonies can be much different than in the macroscopic environment acidic conditions were likely predominant in vast regions of mars over the last four billion years of planetary evolution ancient martian microbial life inhabiting low ph environments could have precipitated carbonates similar to those observed at rio tinto preservation of carbonates at rio tinto over geologically significant timescales suggests that similarly formed carbonate minerals could also be preserved on mars such carbonates could soon be observed by the mars science laboratory and by future missions to the red planet

evidence of phyllosilicates in wooly patch an altered rock encountered at west spur columbia hills by the spirit rover in gusev crater mars 1 on its traverse to columbia hills the mars exploration rover spirit investigated an outcrop designated wooly patch that exhibited morphological mineralogical and geochemical characteristics at the extreme ends of ranges observed among rocks studied at west spur a westward projecting salient near the foot of the columbia hills gusev crater the major element composition and fe mineralogy as determined by the alpha particle x ray spectrometer and mossbauer spectrometer are inconsistent with any reasonable assemblage of basaltic minerals in that there is an excess of si and al the combined data are best explained by the presence of 14 17 phyllosilicate minerals phyllosilicates that account for the composition and cation ratios include members of the kaolinite serpentine chlorite and septechlorite groups the potential existence of kaolinite type al rich phyllosilicates within the wooly patch outcrop suggests a mildly acidic environment ph 4 6 in the past and an open hydrologic system with good drainage conditions in the environment where these rocks were altered

contemporaneous deposition of phyllosilicates and sulfates using australian acidic saline lake deposits to describe geochemical variability on mars 1 studies of the origin of the martian sulfate and phyllosilicate deposits have led to the hypothesis that there was a marked global scale change in the mars environment from circum neutral ph aqueous alteration in the noachian to an acidic evaporitic system in the late noachian to hesperian however terrestrial studies suggest that two different geochemical systems need not be invoked to explain such geochemical variation western australian acidic playa lakes have large ph differences separated vertically and laterally by only a few tens of meters demonstrating how highly variable chemistries can coexist over short distances in natural environments we suggest diverse and variable martian aqueous environments where the coetaneous formation of phyllosilicates and sulfates at the australian sites are analogs for regions where phyllosilicates and sulfates coexist on mars in these systems fe and alkali earth phyllosilicates represent deep facies associated with upwelling neutral to alkaline groundwater whereas aluminous phyllosilicates and sulfates represent near surface evaporitic facies formed from more acidic brines

the late jurassic oblique collisional orogen of sw japan new structural data and synthesis the structural configuration of sw japan mainly reflects a late jurassic early cretaceous orogeny the region is divided into an inner belt and an outer belt on the japan sea and pacific ocean sides respectively by a strike slip fault the median tectonic line mtl both consist of a series of stacked nappes the inner belt is divided into a jurassic olistostrome known as the tanba zone and a hinterland area comprising continental triassic jurassic sediments the tanba zone is sliced into two units a lower one with late jurassic matrix and triassic early jurassic radiolarite olistoliths tectonically overthrust by an upper unit comprising an olistostrome with middle jurassic matrix and blocks which include late paleozoic limestone basic lava and radiolarite the tanba zone is overthrust by a paleozoic nappe complex derived from the hinterland the basal sole of the nappe corresponds to a peculiar unit called the ultra tanba zone in the chugoku area the hinterland is divided into an upper nappe the oga nappe formed by permo carboniferous limestone and permian clastic rocks and a lower one the sangun maizuru nappe formed by paleozoic high pressure hp metamorphics the sangun schists the permian maizuru olistostrome and the dismembered paleozoic yakuno ophiolites in the northern part of sw japan the tanba zone is in faulted contact with the circum hida and the hida zones the former is interpreted as the equivalent of the oga and sangun maizuru nappes of the chugoku domain crushed by post cretaceous tectonics the latter consists of paleozoic high temperature ht metamorphic rocks and late triassic early jurassic granite locally mylonitized and covered by early jurassic sandstone the outer belt is formed by a superficial nappe similar to the tanba zone thrust upon a deep domain characterized by a synmetamorphic ductile deformation the deep domain is divided into a lower unit the oboke unit formed by continental derived arenites and a green schist nappe consisting of oceanic sediments and resedimented ophiolites the green schist nappe overthrusts the oboke unit under synmetamorphic conditions with an eastward displacement the two belts are separated by the ryoke zone which corresponds to the southern part of the tanba zone affected by a cretaceous ht metamorphism and sharply cut by the mtl a geodynamic model is proposed for the jurassic orogeny of sw japan assuming that the evolution of the inner and outer belts are linked in the late triassic early jurassic sw japan is an active plate margin the upper plate or south china block consisted of the hinterland and the tanba belt a forearc basin the lower plate consisted of an oceanic area and the south japan continent the basic mechanism of the orogeny is ascribed to the oblique subduction and collision of the south japan continent

orbital identification of carbonate bearing rocks on mars geochemical models for mars predict carbonate formation during aqueous alteration carbonate bearing rocks had not previously been detected on mars surface but mars reconnaissance orbiter mapping reveals a regional rock layer with near infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the nili fossae region the carbonate is closely associated with both phyllosilicate bearing and olivine rich rock units and probably formed during the noachian or early hesperian era from the alteration of olivine by either hydrothermal fluids or near surface water the presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering proposed to be characteristic of hesperian mars did not destroy these carbonates and thus did not dominate all aqueous environments

the miller volcanic spark discharge experiment miller9s 1950s experiments used besides the apparatus known in textbooks one that generated a hot water mist in the spark flask simulating a water vapor rich volcanic eruption we found the original extracts of this experiment in miller9s material and reanalyzed them the volcanic apparatus produced a wider variety of amino acids than the classic one release of reduced gases in volcanic eruptions accompanied by lightning could have been common on the early earth prebotic compounds synthesized in these environments could have locally accumulated where they could have undergone further processing

a survey of the jurassic system of china terrestrial jurassic rocks are widespread in china whereas marine jurassic rocks are confined to xizang tibet south qinghai south xinjiang and in limited parts of the sequence to west yunnan guangdong south hunan and east heilongjiang geographically occurrences of jurassic deposits may be divided into three regions and 13 districts i the xizang qinghai region with the south tethyan himalayan north tethyan himalayan lhasa xanza shiquanhe bangon dengqen karakorum tanggula and qamdo districts ii the coastal volcanic region of east china with the guangdong hunan fujian zhejiang heilongjiang and northeast china districts and iii the stable giant basin region of west china with the sichuan yunnan and northwest china districts these regions and districts are described briefly and preliminary biostratigraphic sequences and palaeogeography are presented the upper and lower boundaries of the jurassic system in china are briefly discussed the jurassic seas of china evidently were

a 3 5 ga record of water limited acidic weathering conditions on mars abstract the secondary mineral budget on earth is dominated by clay minerals al hydroxides and fe oxides which are formed under the moderate ph high water to rock ratio conditions typical of earth s near surface environment in contrast geochemical analyses of rocks and soils from landed missions to mars indicate that secondary mineralogy is dominated by mg fe ca sulfates and fe oxides this discrepancy can be explained as resulting from differences in the chemical weathering environment of earth and mars we suggest that chemical weathering processes on mars are dominated by 1 a low ph sulfuric acid rich environment in which the stoichiometric dissolution of labile mineral phases such as olivine and apatite fe ti oxides is promoted and 2 relatively low water to rock ratio such that other silicate phases with slower dissolution rates e g plagioclase pyroxene do not contribute substantially to the secondary mineral budget at the martian surface under these conditions al mobilization is limited and the formation of significant al bearing secondary phases e g clays al hydroxides al sulfates is inhibited the antiquity of rock samples analyzed in situ on mars suggest that water limited acidic weathering conditions have more than likely been the defining characteristic of the martian aqueous environment for billions of years

organic burial site on mars the nili fossae region on mars is one of the places earmarked for the search of evidence for life a combination of geomorphological and mineralogical data from the area suggest ideal conditions for the burial of organic matter

interaction of fluctuating river flow with a barotropic tide a demonstration of wavelet tidal analysis methods wavelet transforms provide a valuable new tool for analysis of tidal processes that deviate markedly from an assumption of exact periodicity inherent in traditional harmonic analysis a wavelet basis adapted to nonstationary tidal problems is constructed and employed to analyze the modulation of the external tide in a river by variations in streamflow interaction of a surface tide with river flow is the best available demonstration of the continuous wavelet transform cwt methods developed it is the simplest and perhaps the only nonstationary tidal process for which both sufficient data and dynamical understanding exist to allow detailed comparisons between cwt analyses and analytical predictions of the response of tides to nontidal forcing variations at upriver locations of low frequency elevation river stage zr and three tidal species are deduced from cross sectionally integrated equations for landward propagation in a channel of constant cross section with quadratic friction the log of the amplitude of the diurnal d1 semidiurnal d2 and quarterdiurnal d4 elevations should vary at far upriver locations with the square root of the river flow qr and river stage zr should depend on the square of river flow convergent geometry and species species frictional interactions modify these predictions somewhat cwt analyses show that the predicted amplitude behavior for the tidal species is approximately correct best results are obtained for the dominant dynamically simplest processes zr and d2 in the past further progress in understanding river tides has been limited by a lack of data analysis tools data analysis tools are now clearly better than the available analytical solutions

reconstruction of spatially continuous water levels in the columbia river estuary the method of empirical orthogonal function revisited abstract accurate water level measurements in tidal rivers are vital and essential for water resources management coastal engineering and hydrodynamic research however the number of tide gauging stations in tidal rivers is far from adequate in this paper we revisit the method of empirical orthogonal function eof which is widely used in geophysics for spatial temporal data different from previous studies which used eof as a data analysis method here eof is used as a data interpolation method to reconstruct spatially continuous water levels in the fluvial estuary the eof interpolation eofi decomposes spatial temporal water levels into spatial patterns and temporal patterns and then eofi spatially integrates tidal heights using the interpolated spatial patterns between the stations eofi is simple to understand and easy to implement while its results are highly accurate moreover different from numerical modeling which needs the bathymetry river shorelines and river flow data eofi only needs the water level data in summary although eofi has some limitations it has the potential to be widely used in reconstructing water levels and other spatial temporal parameters

assessment of environmental controls on acid sulfate alteration at active volcanoes in nicaragua applications to relic hydrothermal systems on mars 1 a variety of secondary mineralogies has been detected on mars from both orbiters and landers indicating widespread aqueous alteration of the crust many of these locales exhibit sulfates which in some cases imply acidic fluids at present there are few constraints on the paleoenvironmental conditions that existed during formation of the widespread and diverse classes of secondary minerals on mars we investigated hydrothermal systems at three active acidic volcanic systems in nicaragua including cerro negro momotombo and telica the recently erupted materials are similar in composition to the martian crust and are undergoing extensive acid sulfate alteration predominately in gas dominated settings fumaroles we characterized the secondary mineralogy and local variables including temperature ph rock and gas composition and fluid rock ratio we find that these environmental parameters exhibit strong controls on the alteration mineralogy the environments studied include ph that ranged from 1 to 6 temperatures from ambient to hundreds of degrees celsius and fumaroles to hot springs the hottest and most acidic systems contained sulfur silica and minor gypsum while moderately acidic and cooler fumaroles included abundant silica gypsum and other hydrated sulfates and phyllosilicates a setting with a higher fluid rock ratio but similar temperature and acidity was dominated by phyllosilicates and to a lesser degree sulfates the characterization of aqueous alteration of basalts under a variety of environmental conditions provides a conceptual framework for interpretation of similar relic environments on mars finally while identification of phyllosilicates on mars is generally thought to require neutral to alkaline fluids we documented significant formation of these minerals in the acidic volcanic systems

relation between tidal damping and wave celerity in estuaries observations in estuaries indicate that an amplified tidal wave moves considerably faster than is indicated by the classical equation for wave propagation similarly the celerity of propagation is lower if the tidal wave is damped this phenomenon is clearly observed in the schelde estuary located in the netherlands and belgium and in the incomati estuary in mozambique in the incomati the tidal wave is damped throughout whereas in the schelde the tidal range increases from the mouth until the city of antwerp after which it decreases until gent this paper derives a new analytical expression for the celerity of the tidal wave that takes into account the effect of tidal damping as an expansion of the classical equation for tidal wave propagation in the new equation the phase lag between high water and high water slack plays a crucial role it is one of the main parameters determining tidal wave propagation in alluvial estuaries the equation is successfully applied to observations in the schelde and the incomati

impacts of columbia river discharge on salmonid habitat 1 a nonstationary fluvial tide model 1 this is the first part of a two part investigation that applies nonstationary time series analysis methods and the st venant equations to the problem of understanding juvenile salmonid access to favorable shallow water habitat in a tidal river habitat access is a function of river stage tidal range and the distribution of bed elevation part 1 models nonstationary tidal properties species amplitudes and phases and tidal range part 2 models low frequency river stage in the lower columbia river and reconstructs historical water levels using the tidal model from part 1 to incorporate the nonstationary frictional effects of variable river discharge into the tidal model we decompose the tidal wave into tidal species and calculate daily tidal range our one dimensional tidal model is based on analytic wave solutions to the linearized st venant equation and uses six coefficients per tidal species to represent the upstream evolution of the frictionally damped tidal wave the form of the coefficients is derived from the st venant equations but their values are determined objectively from the data about 50 station years of surface elevation data collected 1981 2000 below bonneville dam 235 km from the ocean were processed with a wavelet filter bank to retrieve time series of tidal species properties a min max filter was used to estimate daily tidal range tidal range diurnal and semidiurnal amplitudes were predicted with mean root mean square errors 30 mm which is significantly more accurate than predictions obtained from harmonic analysis thus despite the compact form of our solution we model nonstationary fluvial tidal properties with a high level of accuracy

discharge estimation from h adcp measurements in a tidal river subject to sidewall effects and a mobile bed horizontal acoustic doppler current profilers h adcps can be employed to estimate river discharge based on water level measurements and flow velocity array data across a river transect a new method is presented that accounts for the dip in velocity near the water surface which is caused by sidewall effects that decrease with the width to depth ratio of a channel a boundary layer model is introduced to convert single depth velocity data from the h adcp to specific discharge the parameters of the model include the local roughness length and a dip correction factor which accounts for the sidewall effects a regression model is employed to translate specific discharge to total discharge the method was tested in the river mahakam representing a large river of complex bathymetry where part of the flow is intrinsically three dimensional and discharge rates exceed 8000 m3 s 1 results from five moving boat adcp campaigns covering separate semidiurnal tidal cycles are presented three of which are used for calibration purposes whereas the remaining two served for validation of the method the dip correction factor showed a significant correlation with distance to the wall and bears a strong relation to secondary currents the sidewall effects appeared to remain relatively constant throughout the tidal cycles under study bed roughness length is estimated at periods of maximum velocity showing more variation at subtidal than at intratidal time scales intratidal variations were particularly obvious during bidirectional flow conditions which occurred only during conditions of low river discharge the new method was shown to outperform the widely used index velocity method by systematically reducing the relative error in the discharge estimates

seasonal changes in river tide dynamics in a highly human modified estuary modaomen estuary case study abstract many estuaries worldwide are subject to significant human interventions such as dam construction channel deepening and land reclamation however the impact of these interventions on the spatiotemporal river tide dynamics is insufficiently understood in this study we explored the seasonal changes in river tide dynamics in the modaomen estuary of the pearl river where a significant increase in tidal range by approximately 0 14 m on average was observed after substantive channel deepening mainly due to human induced sand excavations using the double mass curve approach with regard to the river discharge and the absolute value of tidal damping rate or residual water level slope we identified three stepwise phases i e 1960 1990 representing the pre human intervention period 1991 2000 representing the transitional period and 2001 2016 representing the post human intervention period corresponding to high to low residual water level slopes and qualitatively matched the river tide dynamics shift observed in the modaomen estuary it was shown that the increase in tidal range was primarily due to the reduction in residual water level slope and thus the weakening of the tidal damping effect caused by the channel deepening along the modaomen estuary with length of 124 km where the residual water level slope was decreased by 46 from the pre human period 1960 1990 to the post human period 2001 2016 while the absolute value of the tidal damping rate was decreased by 32 due to the overall impacts from human interventions based on the regression coefficients obtained from the double mass curve approach we showed that the river tide dynamics in terms of tidal damping rate and residual water level slope were more sensitive to human interventions during the dry season than during the wet season owing to the combined impacts of riverbed deepening and freshwater regulation by dam s operation the underlying mechanism could be primarily attributed to the considerable seasonal variation in the lateral storage area such as tidal flats or salt marshes the results also showed that larger freshwater discharge is required to alter the critical value of maximum tidal damping indicating the strongest damping effect along the channel owing to the increase in tidal range due to substantial riverbed deepening and hence significant increase in channel storage the method proposed in this study to quantify the overall impacts of human interventions on seasonal changes in river tide dynamics is particularly useful for setting scientific guidelines for sustainable water management and conservation planning for engineering works in the modaomen estuary and other estuaries with significant human interventions

prediction of surface currents and drifter trajectories on the inner scotian shelf 1 the predictive skill of a simple model of surface flow on the scotian shelf is assessed using oceanographic data collected in february 1996 the model is forced by wind stress water density and sea level along the open boundaries of the model domain the skill of the model with respect to subtidal variations of alongshore current and bottom pressure is quantified by the ratio 2 var o p var o where var o p and var o are the variance of the prediction errors and observations respectively skill is highest for bottom pressure 2 0 2 followed in order by cross shelf gradients in bottom pressure 2 0 5 horizontally averaged currents 0 4 2 0 7 and currents at individual current meters 0 6 2 1 4 the skill of the model with respect to drifter position is quantified by the search radius centered on the predicted drifter position that ensures a 50 chance of locating the drifter skill varies significantly with time but is generally highest when the drifter motion is strongest we conclude with a comparison of the performance of the model against predictions based on the release point of the drifters and the operational scheme presently used to guide marine search and rescue in this region