characteristic straight chain lipid ratios as a quick method to assess past forest paramo transitions in the ecuadorian andes to assist sustainable reforestation efforts in the andes in northern ecuador the position of the natural upper forest line ufl has to be assessed to this end new vegetation reconstruction techniques to complement traditional reconstruction methods such as pollen analysis are being developed one such technique is the biomarker ratio approach that uses changes in characteristic ratios of extractable lipids such as n alkanes and n alcohols for a quick assessment at high spatial resolution of abrupt past vegetation changes in the present study we assessed the applicability of this approach as indicator of past vegetation shifts from forest to paramo or vice versa in northern ecuador we looked at the n alkane and n alcohol signals of two soil monoliths one taken in a forest patch located 100 m above the current ufl and the other at the same altitude in the surrounding paramo the monoliths were sampled to a depth corresponding to at least 1500 cal yr bc links were sought between biomarker ratio signals in soil organic matter som and those found in plants from the vicinity during previous research based on the outcome an attempt was made at determining whether the forest patch had been part of the continuous forest further down slope during the last 3500 cal years results show that specific ratios of extractable straight chain lipids can be used to get a quick indication of whether an area was forested or not in the past in som the n alkane relationship c29 c31 1 combined with the n alcohol relationship c22 c24 1 was found to be characteristic for dominant forest vegetation while the opposite relationships were indicative for past paramo vegetation the n alkane relationship could be explained very well by the lipid ratios of the current forest and paramo vegetation in the area while agreeing well with the n alkane signal the n alcohol signal was less robust probably partially due to degradation of wax esters in the soil contrary to expectations we conclude that the investigated forest patch was never part of the continuous forest in the vicinity in the past 3500 cal years instead our biomarker ratio approach suggests that the forest patch soil was once covered by paramo vegetation overall this study shows that the biomarker ratio approach in volcanic ash soils can serve as a quick method for an assessment of abrupt vegetation changes such as associated with past ufl shifts at a high spatial resolution and at the location where the shift occurred as such it is highly complementary to traditional proxies such as pollen analysis

short period fluctuations of the diurnal tide observed with low latitude mf and meteor radars during cadre evidence for gravity wave tidal interactions mf and meteor radar data from four equatorial and subtropical sites hawaii christmas island jakarta and adelaide are used to examine diurnal tide amplitude and phase variability at mesosphere and lower thermosphere altitudes all sites exhibit significant seasonal variability with the largest amplitude fluctuations occurring at hawaii and adelaide shorter term variability is found to occur primarily on timescales of 5 to 30 days amplitude and phase fluctuations are well correlated among different sites on occasion but in general the amplitude and phase coherences are low and suggest significant local influences on the tidal structures the temporal behavior of height variations of the diurnal tide amplitude and phase is also examined cross correlations and cross spectra of these tidal parameters especially between the amplitude and phase are examined closely the tendency for phase maxima to lead amplitude maxima is consistent with tidal modulation of gravity wave propagation and momentum fluxes with a corresponding feedback by the gravity wave momentum flux divergences on the observed tidal structures these results substantially extend previous more limited studies of gravity wave tidal interactions and provide a statistical basis for the possible importance of this interaction and its influences on the diurnal tidal structure

empirical model of 90 120 km horizontal winds from wind imaging interferometer green line measurements in 1992 1993 an empirical model of horizontal winds is developed based on wind imaging interferometer windii green line observations between 90 and 120 km in 1992 1993 the model includes mean winds solar diurnal and semidiurnal tides and some planetary wave components as well as annual and semiannual variations in these fields its formulation is similar to that of hwm 90 and hwm 93 of hedin et al 1991 1996 but greatly modified and extended to use the higher resolution global wind measurements now available from windii while the technique will only reach fruition when results can be combined from the wind measurements of several years by the different instruments on the uars satellite this interim but updated model provides improved representation of the temporal and geographic variations of the wind fields compared to the current reference models the model generated climatological mean wind diurnal tides and some samples of the entire wind motion fields are presented and compared with the windii measurements and analysis results obtained from the data sets by different methods to check the consistencies between the model representations and the observations this study also reveals a dual cell structure in the meridional component of the diurnal tides with two amplitude maxima centered around 95 and 102 km near 20 latitude and strongly symmetric about the equator at equinox large interannual variabilities are found to exist in both diurnal wind components with maximum amplitudes of 40 and 55 m s for the zonal and meridional respectively at the vernal equinox of 1992

stationary planetary waves inferred from windii wind data taken within altitudes 90 120 km during 1991 96 abstract a climatology of stationary planetary waves spws in horizontal winds at latitudes 70 s 70 n and altitudes 90 120 km is obtained from wind imaging interferometer windii green line measurements in december january and march april of 1991 96 the observed solstitial spw fields are relatively stronger and dominated by zonal wavenumber 1 variations in contrast the equinoctial spw fields are weaker and characterized by zonal wavenumber 2 variations the zonal amplitude maxima of 10 25 m s 1 are generally centered at the midlatitudes of 35 40 in both hemispheres around 96 km with the eastward perturbation velocity maxima around 90 e for wavenumber 1 and 60 and 240 e for wavenumber 2 the meridional amplitude maxima are about 5 15 m s 1 and show more variabilities in their latitude height distributions the meridional phases indicated that eliassen palm ep fluxes were downward poleward for the winter maxima vertically varying poleward for the summer maxima and more variable during march apr

diagenetic controls on the reservoir properties of gas bearing neogene surma group sandstones in the bengal basin bangladesh abstract the diagenetic history of neogene reservoir sandstones of the surma group is described based on petrological analyses of over fifty core samples from four onshore boreholes in the bengal basin of bangladesh diagenesis in the sandstones principally involves the development of cements in the following order chlorite siderite illite quartz and fe calcite there is also a late dissolution stage creating secondary porosity via the dissolution of feldspars and carbonate cements which was followed by the generation of a kaolinite cementing phase these latter processes require acidic pore waters which are considered to have been produced during the maturation of organic matter in the adjacent miocene source rocks in some of the sandstones an early poikilotopic fe calcite cement formed and effectively halted further diagenesis after the formation of the chlorite and siderite the carbonate and quartz overgrowth cements have caused the most significant decreases in the porosity values with the clays having less effect and may even have helped preserve porosity secondary porosity occurs at depth but its effect is reduced by the generation of the late phase kaolinite cement in the secondary pore spaces

diurnal nonmigrating tides from timed doppler interferometer wind data monthly climatologies and seasonal variations 1 timed doppler interferometer tidi measurements of zonal and meridional winds in the mesosphere lower thermosphere are analyzed for diurnal nonmigrating tides june 2002 to june 2005 climatologies of monthly mean amplitudes and phases for seven tidal components are presented at altitudes between 85 and 105 km and latitudes between 45 s and 45 n westward propagating wave numbers 2 3 and 4 the standing diurnal tide and eastward propagating wave numbers 1 2 and 3 the observed seasonal variations agree well with 1991 1994 uars results at 95 km comparisons between the tidi results and global scale wave model gswm and thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm tidal predictions indicate that the large eastward propagating wave number 3 amplitude is driven by tropical tropospheric latent heat release alone in contrast latent heating and planetary wave migrating tidal interactions are equally important to westward 2 and standing diurnal tidal forcing there is good quantitative agreement between tidi and the model predictions during equinox but the latter tend to underestimate the westward 2 and standing diurnal tide during solstice neither model reproduces the observed seasonal variations of the eastward propagating components

reconstructing the avalonia palaeocontinent in the cambrian a 519 ma caliche in south wales and transcontinental middle terreneuvian sandstones an early cambrian caliche on the st non9s formation emended is the base of the caerfai bay formation unit term changed at caerfai bay south wales subaerial exposure and the caliche mean the two formations were not genetically related units the st non9s is an older sand sheet likely tidalitic not delta related referred to avalonian depositional sequence ads 2 and the caerfai bay is a shallow mud basin unit refered to ads 4a the similar random formation upper ads 2 in north american avalonia has a basal age of c 528 ma and is unconformably overlain by red mudstones or sandstones in fault bounded basins on the avalonian inner platform coeval british sandstones lower hartshill wrekin st non9s brand hills are unconformably overlain by latest terreneuvian ads 3 or epoch 2 ads 4a units dates of 519 ma on caerfai bay ashes give an upper bracket on the late appearance of avalonian trilobites and suggest an ads 2 4a hiatus of several million years post st non9s and post random basin reorganization led to abundant caerfai bay formation volcanic ashes and sparse brigus formation ashes in newfoundland the broad extent of erosional sequence boundaries that bracket lithologically similar to identical units emphasize that east and west avalonia formed one palaeocontinent the inner platform in southern britain was larger than the midlands craton a tectonically defined later palaeozoic area unrelated to terminal ediacaran early palaeozoic depositional belts the cool water successions of early palaeozoic avalonia were distant from coeval west gondwanan carbonate platforms

gravity wave interactions with the diurnal propagating tide observations of the diurnal propagating solar tide in the mesosphere and lower thermosphere 50 150 km indicate substantial annual variations in tidal amplitudes observations and modeling efforts suggest that interactions with internal gravity waves can result in significant modifications of the diurnal tide herein a two dimensional 2 d linear steady state tidal model is used in conjunction with hybrid lindzen matsuno gravity wave parameterization to examine the role of gravity wave interactions in the seasonal variability of the diurnal tide in the mlt the analysis indicates that annual variations of the background atmosphere result in significant annual variations in the eddy diffusion and the diurnal harmonic of the momentum flux divergence wave stress produced by breaking gravity waves the seasonal variability in these two mechanisms can explain the observed semi annual variability in the diurnal tide amplitude minima at solstice and maxima at equinox the relative roles of wave stress and diffusion are examined and it is shown that both play important roles in tidal modification by damping its amplitude the effects of varying inputs to the gravity wave parameterization are explored

origin and growth mechanism of authigenic chlorite in sandstones of the lower vicksburg formation south texas abstract authigenic chlorite occurring as grain coatings pore fillings and rosettes is common in deltaic sandstones of the lower vicksburg formation in south texas chlorite rosettes are isolated and occur late in the diagenetic history whereas grain coating and pore filling chlorite occur early predating the development of secondary porosity and the precipitation of quartz overgrowths and fe poor calcite grain coating and pore filling chlorite which are interstratified with approximately 15 percent 7 a layers are fe rich with a mean fe fe mg ratio of 0 68 stable isotope data 18o averages 13 5o oo smow indicate that the grain coating and pore filling chlorite began precipitating between 20 c to 40 c within the upper 1 8 km 6000 ft of burial sandstones of the lower vicksburg formation were deposited in a relatively shallow deltaic environment as part of a large fluvial system draining the volcanics of sierra madre occidental mexico and trans pecos texas weathering of these volcanics brought large amounts of particulate fe to the river mouth an increase in salinity in the distributary channel complex caused fe flocculation and deposition during periods of high river discharge or when coastal currents acted to concentrate particulate fe large amounts of particulate fe were deposited in the delta system this resulted in thick layers of fe rich clay odinite around grains during periods of low river discharge or when coastal currents caused wide distribution of particulate fe less particulate fe was deposited it is proposed that the grain coating and pore filling chlorite began forming through the transformation of an fe rich clay precursor in the formation water hydropressure zone following ostwald processes the presence of this synsedimentary fe rich clay and its recrystallization to fe chlorite strongly influenced fluid flow and played a large role in developing the diagenetic heterogeneity seen in lower vicksburg sandstones today

mesospheric momentum flux studies at adelaide australia observations and a gravity wave tidal interaction model abstract we present here the results of an analysis of gravity wave momentum fluxes in the mesosphere and lower thermosphere inferred using a dual beam doppler radar near adelaide australia during june 1984 our analysis reveals that over 70 of the momentum flux and of the inferred zonal drag was due to gravity waves with observed periods less than one hour this suggests that it is the gravity waves with high intrinsic frequencies and small horizontal scales that are most effective at transporting momentum into the middle atmosphere the temporal variations in the momentum flux and flux divergence due to high frequency motions were also examined in detail in addition to daily variability a strong diurnal modulation was observed to occur this was found to be correlated with the phase of large amplitude diurnal tidal motions as a result of these observations a gravity wave tidal interaction model was proposed which accounts for all of the major features of the observed data including a reduction i

geochemistry petrology and origin of the cenozoic volcanic rocks of the northern andes in ecuador abstract the cenozoic volcanic rocks of the northern andes in ecuador for which only little petrological and geochemical information was available until now display a strong geochemical and petrological zoning from west to east the magmas of the volcanoes of the western cordillera wc are unique to the andes they belong to andesite plagidacite series which is characterized by low and fairly constant k 2 o contents 1 0 2 low abundances of large cation elements rb sr ba rare earth elements highly charged cations zr u th and relatively high ni and cr abundances the magmas of the volcanoes of the eastern cordillera ec belong to andesite andesitedacite rhyolite series which is characterized by rb sr ba ree zr u and th contents higher than in the rocks of the wc and varying with the k 2 o content they have ni and cr versus mgo correlations similar to the rocks of the western cordillera even higher contents of k 2 o and the above mentioned elements are encountered in the volcanic rocks of the sub andean area saa all of the rocks have the same 37 sr 36 sr ratio of 0 704 the rocks are chemically more closely related to the mesozoic to tertiary rocks of the basic igneous complex bic of ecuador and colombia than to those of the central andes it is suggested that the cenozoic magmas of the volcanoes of the western and eastern cordillera originated by hydrous partial melting of amphibolites and garnet amphibolites of the bic type in a subduction zone beneath the cordilleras at pressures near 20 kbar which corresponds to a depth of about 70 km

stratification of parent material in european volcanic and related soils studied by laser diffraction grain sizing and chemical analysis abstract sedimentary stratification identified by field descriptions of 12 soils derived wholly or partly from volcanic materials was compared with results obtained by chemical analyses contents and ratios of lithogenic elements contents of heavy metals and detailed grain size data after removal of organic matter and amorphous fractions the finest sedimentary stratification was indicated by cluster analysis of ratios of lithogenic elements and by the grain size analyses sedimentary stratification in the field is difficult to determine or describe when 1 the deposits are strongly weathered 2 soil horizon boundaries coincide with stratification boundaries or 3 stratification is very fine nevertheless field descriptions are a reasonably good way of differentiating parent materials though they often underestimate the number of sedimentary layers

authigenesis of amphibole and its relationship to the diagenetic evolution of lower cretaceous sandstones of the potiguar rift basin northeastern brazil abstract authigenic amphibole occurs in the fan delta front arkoses and lithic sandstones of the neocomian pendencia formation in the potiguar rift basin northeastern brazil as overgrowths fracture healing and replacement of detrital amphibole the amphibole which is closely associated with diagenetic albite chlorite and sphene has precipitated from k na cl brines enriched in ti fe mg at temperatures 100 c these ions were derived from the diagenetic alteration of detrital amphibole and pyroxene chloritization of volcaniclastic sediments at the base of the formation and from brines that ascended along faults from the underlying basement

mountain wave drag in the stratosphere and mesosphere inferred from observed winds and a simple mountain wave parameterization scheme abstract a daily analysis of mountain wave propagation through observed global wind and temperature fields in january and august is presented winds and temperatures are obtained from the daily 18 level nmc climate analysis center mountain wave properties are deduced from a simple gravity wave parameterization scheme in which the effects of topographic anisotropy ridge orientation are explicitly included planetary waves in the northern winter stratosphere are found to play an important role in modulating the magnitude and distribution of inferred mountain wave drag in the middle atmosphere the aleutian anticyclone is found to effectively block mountain waves generated over western north america from reaching the mesosphere by inducing local mountain wave critical levels in the stratosphere stratospheric sudden warmings have a similar effect at all longitudes so that during months with sudden warmings have a similar effect at all longitudes so that during months with sudden warmings the average in

infiltrated clays in fluvial jurassic sandstones of reconcavo basin northeastern brazil abstract fluvial sandstones and conglomerates of the sergi formation a jurassic unit of reconcavo basin northeastern brazil contain significant amounts of interstitial detrital clays which are interpreted as the product of early mechanical infiltration developed in an arid semi arid environment within such an environment the lowered water table allowed muddy waters of episodic runoff to infiltrate through the coarse alluvium concentrating the clays in the upper phreatic zone near the sources of influent seepage petrographic textures considered to be typical of mechanically infiltrated mi clays are herein presented using examples from the sergi formation these textures include 1 ridges and bridges 2 geopetal fabrics 3 loose aggregates 4 anisopachous coatings of tangentially accreted lamellae cutans 5 massive aggregates and 6 shrinkage patterns developed during diagenesis in addition their detrital aspect as revealed by sem observations and the presence of impurities in the interior of the clay aggregates were also used as evidence for the interpreted origin of the clays in most hydrocarbon reservoirs in the sergi formation the clays described in this paper are among the main controls on porosity and permeability distribution commonly zones with maximum clay concentration are the main internal permeability barriers within the sergi formation reservoirs

observational evidence of tidal gravity wave interactions using the uwo 2 mhz radar the degree of interaction between atmospheric gravity waves and tides is an issue which is of great importance in middle atmosphere studies it is especially important with regard to tidal variability which is frequently observed in the mesosphere and lower thermosphere but as yet has not been subject to adequate study in this paper we present some strong observational evidence of such interactions made with the uwo 2 mhz radar near london canada our observations show significant correlation between gravity waves and tides diurnal at certain times of the year and the nature of the correlation is intermittent and varies with time of year it is possible that differences between tidal amplitudes at sites with mesoscale separations may be explained in terms of such phenomena we also propose a simple model which is found to be consistent with the major features of the observed data

constitutive mass balance relations between chemical composition volume density porosity and strain in metasomatic hydrochemical systems results on weathering and pedogenesis relations characterizing the chemical physical and mechanical changes resulting from metasomatic hydrochemical processes are developed using mass balance models which formally link chemical composition to bulk density mineral density volumetric properties porosity and amount of deformation strain rigorous analysis of aqueous solute transport effects is then made possible in a variety of porous media flow environments including chemical weathering pedogenesis soil formation diagenesis ore deposition and enrichment and metamorphism application of these linear constitutive relations to chemical weathering profiles shows that immobile and locally mobile chemical elements with masses conserved on the scale of soil profiles can be accurately identified from analysis of appropriate data arrays and then used as natural geochemical tracers to infer the nature and extent of hydrochemical weathering processes and volume changes during pedogenesis assumptions commonly made in the past about the supposed immobility of certain elements e g ti and zr become unnecessary quantitative differentiation between the effects of residual and supergene fractionation is then easily made these methods are applied to ni rich laterites developed by weathering of ultramafic rocks showing that during ordinary residual enrichment ni is concentrated by as much as 4 protolith peridotite concentrations this occurs simply by silicate mineral dissolution and removal of chemical elements other than ni e g mg with a corresponding reduction in saprolite density and increase in bulk porosity without significant deformation in contrast laterites with mineable concentrations of ni which are similarly undeformed such as the nickel mountain mine in riddle oregon have experienced in addition to residual enrichment strong supergene enrichment by fractionation of ore elements between a leached zone from which ni is extracted and a complementary enriched zone positioned farther along the direction of ground water flow soil forming processes in podzol chronosequences developed on sandy beach terraces of the mendocino coast of california involved soil column collapse of 60 percent by dissolution of silicate minerals in the albic horizon of al and fe leaching and 70 percent dilation expansion in the overlying organic rich layer by root growth the amount of erosion based upon paleosurface reconstructions using the excess mass of fe al pb ga and cu in the zone of supergene enrichment spodic horizon below the ground water table indicates that subsurface erosion by dissolutional collapse is three times that of surficial erosion finally using published chemical data for ti zr and cr on major bauxite deposits in australia where erosion rates are thought to be low we infer that there may have been major amounts of dissolutional collapse to explain the upwards increase of detrital zircon and rutile in weathering profiles

direct observations of nonmigrating diurnal tides in the equatorial thermosphere 1 we present direct observations of nonmigrating diurnal tides in the 90 270 km range inferred from the upper atmosphere research satellite uars wind imaging interferometer windii a prominent zonal wavenumber 4 appears in daytime zonal winds extending to 180 km we interpret this signature as an eastward propagating diurnal wavenumber 3 de3 viewed from the satellite perspective this evidence of the extended upward propagation of de3 demonstrates that it acts as a direct coupling agent between the troposphere and the thermosphere and f region in addition to its role in the e region dynamo

oxygen isotope studies of diagenesis in the basal belly river sandstone pembina i pool alberta abstract the oxygen isotope compositions of authigenic clay and carbonate minerals from the pembina i pool basal belly river sandstone provide useful constraints on the diagenesis of this unit early diagenetic chlorite has 18o values 4 2 to 6 3 smow compatible with low temperature crystallization from brackish water the 18o values of diagenetic calcite 11 8 to 14 7 smow and kaolinite 10 4 to 12 8 smow are best explained by crystallization at temperatures of at least 45 to 70 c from pore fluids similar in 18o to the existing formation water 9 smow the implicatio of such temperatures is that the sandstone was much more deeply buried in the past than it is at present at least 1 300 1 400 m of overlying material may have been eroded since maximum burial

global temperature stationary planetary waves extending from 20 to 120 km observed by timed saber version 1 07 temperature measurements from saber instrument on board of timed satellite during 2006 2007 are used to study the temperature stationary planetary waves spws from 20 to 120 km to cover the high latitudes in both hemispheres 80 degrees s 80 degrees n and most local times 120 day data are combined together into one data set the most pronounced spw features are the large amplitudes in the upper mesosphere and lower thermosphere umlt while the spws below 90 95 km share common features with previous observations in both hemispheric umlt spws amplitudes are large at middle and high latitudes throughout the year while their amplitudes in tropics are small wave 1 activity is generally stronger than the corresponding wave 2 activity with maximum amplitudes larger than 15 k occurring at about 60 degrees 70 degrees north or south at the altitudes between 112 km and 119 km wave 1 amplitudes are larger in the southern hemisphere sh than in the northern hemisphere nh their phases are normally tilt westward with increasing height below similar to 110 km above this altitude the wave 1 and wave 2 phases remain nearly unchanged with height indicating the in situ generations and no propagations comparisons between the observed spw structures and those from the nrlmsise 00 model have been done result shows their consistent features below similar to 80 km and that nrlmsise 00 model gives no spw information from 95 to 125 km but does have longitudinal variations above similar to 125 km that are similar to the observed spw features above similar to 110 km

evidence of gravity wave tidal interaction observed near the summer mesopause at poker flat alaska abstract an analysis of gravity wave tidal interaction observed near the mesopause by the mst radar at poker flat in july of 1986 is presented our observations revealed daily mean wind maxima of 60 m s 1 westward and 20 m s 1 southward with daily mean momentum fluxes contributed by gravity waves with periods less than 1 hour of 4 5 m2 s 2 eastward and 1 2 m2 s 2 northward considerable hourly height variability was found to exist for both winds and momentum fluxes a significant modulation of the fluxes by tidal winds was observed characterized by out of phase correlations over a number of heights diurnal and semidiurnal winds and momentum fluxes exhibited very similar height variations with amplitudes of 5 30 m s 1 and 1 5 m2 s 2 meridional winds leading zonal winds by 90 and maximum fluctuating winds and momentum fluxes at lower levels the observed variations in the amplitude and phase of winds and momentum fluxes provide some support to the gravity wave tidal interaction model proposed

diagenesis of terry sandstone upper cretaceous spindle field colorado abstract this study discusses the influence that sedimentology diagenesis and basin subsidence history have on porosity and permeability of the upper cretaceous terry sandstone of spindle field in the denver basin the terry sandstone consists of lithic subarkoses and feldspathic litharenites deposited in a marine bar complex the reservoir facies which was deposited in a marine bar crestal position is a cross bedded sandstone with a mixture of primary and secondary macropores approximately half of the pore volume is microporosity associated with clay minerals and lithic fragments the nonreservoir facies was deposited on the bar flank margin as lower energy alternating layers of mud and sand which were extensively bioturbated to produce muddy sands ductile deformation of lithic fragments is a major factor in porosity loss for the reservoir facies chlorite and calcite are the most important mineral cements authigenic quartz dolomite ferroan calcite kaolinite feldspar pyrite and tourmaline are present in minor to trace amounts precipitation of these minerals is believed to be related to the evolution of marine water secondary porosity formed by dissolution of pore filling and replacement calcite and framework feldspars sandstones with pervasive calcite cement have no secondary porosity developed which suggests some permeability may be needed to develop secondary porosity plagioclase feldspars become more albitized with increasing depth a temperature depth subsidence profile predicts a maximum temperature of only 85 c at least 15 lower than in tertiary rocks which suggests that kinetic considerations may also be important to albitization vitrinite reflectance 0 65 and interbedded shales with ordered mixed layered illite smectite with up to 50 expandability also support the lower temperature regime calculations suggest that seawater can supply sufficient sodium to account for albitization albitization proceeded more rapidly in permeable sandstone where the plagioclase was in direct contact with the pore fluids plagioclase in relatively impervious sandstones eventually became albitized probably through diffusion

solar tides as revealed by measurements of mesosphere temperature by the mls experiment on uars abstract temperatures between 25 and 86 km measured by the microwave limb sounder mls experiment on the upper atmosphere research satellite uars are analyzed to delineate diurnal semidiurnal and terdiurnal tidal structures and stationary planetary waves these fourier components are determined from temperatures averaged in bins covering 5 latitude 30 longitude and 1 h in local time this study confirms the presence of diurnal nonmigrating tides with zonal wavenumbers s 0 2 3 s 0 s 0 implying westward eastward propagation and semidiurnal tides with s 1 and 3 and some components of lesser importance that were previously determined from uars wind measurements near 95 km the seasonal latitudinal and height structures of these components are now revealed and utilized to aid in interpreting their behaviors and ascertaining their origins new discoveries include the terdiurnal s 2 and s 4 components and trapped nonmigrating diurnal tides with s 0 and s 2 the former are like

pleistocene macrotidal tide dominated estuary delta succession along the dong nai river southern vietnam abstract this paper focuses on the facies and sequence stratigraphic interpretation of a tide dominated incised valley system that is rare among geological records of the world for its completeness the subject is the middle upper pleistocene ba mieu and thu duc formations exposed along the dong nai river southern vietnam both the ba mieu and the thu duc formations are interpreted as a transgressive tide dominated estuary succession overlain by a highstand tide dominated delta succession the tide dominated estuary succession is generalized as follows in ascending order fluvial facies in landward portions tidal flat upward coarsening and thickening succession of marine sands with a tidal ravinement surface trs created by tidal scouring during transgression at the base and subtidal lag in seaward portions this tide dominated estuary is distinguished from wave dominated and wave and tide dominated estuaries by 1 the lack of a central basin lagoon tidal delta or bayhead delta facies 2 the widespread presence of marine sands 3 the presence of a subtidal lag and 4 the presence of an upper flow regime sand flat facies the tide dominated delta succession is generalized as follows in ascending order upward convex unit of marine sand and onlapping tidal flat deposits a thick upward fining succession of tidal flat salt marsh deposits and coarse fluvial deposits this delta is distinguished from an estuary as follows 1 it shows thick regional upward fining successions indicating shallowing whereas upward coarsening successions indicating deepening are recognized in an estuary a maximum flooding surface mxfs is recognized in the coarsest part of the succession in marine sand and tidal flat deposits 2 fluvial processes dominate the sediment supply in contrast to an estuary in which a thick marine sand body fed from marine sources is dominant 3 ebb tidal currents are dominant whereas flood tidal currents are dominant in an estuary key features of the incised valley system are 1 amplification of the incised valley geometry by tidal ravinement erosion 2 development of tidal channels filled with mud clasts in the estuary 3 a thick marine sand body in the estuary and 4 upward convex unit of marine sand and a thick tidal flat fluvial succession in the delta the ba mieu formation is recognized as depositional sequence sq 1 between sequence boundary sb 1 below and sb2 above sq1 consists of transgressive systems tract tst 1 and highstand systems tract hst 1 sq1 was formed by a transgression regression cycle during marine isotope stage mis 7 sb2 was formed by fluvial incision during the mis 6 lowstand and is amalgamated with the trs of mis 5 the thu duc formation is recognized as sq2 between sb2 below and sb3 above and it consists of tst2 and hst2 sq2 was formed by a major transgression regression cycle on which a lower rank cyclicity was superposed during mis 5 tst2 thins seaward as a result of tidal ravinement erosion the landward extent of marine environment in mis 5 is inferred to have been of greater scale than that in mis 7 from the distribution of the facies and the trs

paragenesis and reservoir quality within a shallow combination trap central west virginia sandstone character and reservoir quality of the lower mississippian pocono big injun sandstone were examined in granny creek stockly field clay county west virginia sixty three samples from 6 wells were analyzed using transmitted light x ray diffraction and scanning electron microscopy techniques the pocono big injun formation is divided into four sands injun 1 through 4 based on composition and hydrocarbon productivity the injun 1 sand is a fine grained carbonate cemented litharenite below the oil producing zone the oil productive injun 2 and 3 sands are well sorted fine grained litharenites which contain more authigenic and allogenic clay minerals than adjacent sands these sands have produced more than 3 4 million bbl of oil from the granny creek part of the field since 1925 the injun 4 sand is generally a coarse grained sublitharenite with marginal gas production limited to the uppermost section of the sand the paragenetic sequence consists of 1 minor quartz overgrowths 2 illite and chlorite grain coatings 3 quartz overgrowths 4 early carbonate 5 kaolinite 6 calcite 7 dolomite and 8 pyrite porosity and permeability were not preserved once paragenesis progressed past the kaolinite stage porosity and permeability are variably preserved when steps in the paragenetic sequence are absent within the pocono group where any porosity is identified within the pocono sandstones primary porosity is dominant however secondary porosity and microporosity in clay rich intervals are also important secondary porosity was c eated by the dissolution of cements and detrital grains authigenic chlorite grain coatings may not be responsible for preserving primary porosity in the big injun sands

dish structures in some paleocene deep sea sandstones norwegian sector north sea origin of the dish forming clays and their effect on reservoir quality abstract the clay mineralogy of dish structured sandstones supports the intrastratal rather than the interstratal redistribution of clays during the formation of dish structures authigenic fe chlorite is the predominant constituent clay mineral in the dish structures interbedded mudstones comprise illite smectite with minor illite and chlorite dish structured horizons cause a marked reduction in average vertical permeability

southern argentina agile meteor radar system design and initial measurements of large scale winds and tides 1 the southern argentina agile meteor radar saamer was installed at rio grande on tierra del fuego 53 8 s 67 8 w in may 2008 and has been operational for 24 months this paper describes the motivations for the radar design and its placement at the southern tip of south america its operating modes and capabilities and observations of the mean winds planetary waves and tides during its first 20 months of operation saamer was specifically designed to provide very high resolution of large scale motions and hopefully enable direct measurements of the vertical momentum flux by gravity waves which have only been possible previously with dual or multiple beam radars and lidars or in situ measurements saamer was placed on tierra del fuego because it was a region devoid of similar measurements the latitude was anticipated to provide high sensitivity to an expected large semidiurnal tide and the region is now recognized to be a hot spot of small scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere perhaps the most dynamically active location on earth saamer was also intended to permit simultaneous enhanced meteor studies including head echo and nonspecular measurements which were previously possible only with high power large aperture radars initial measurements have defined the mean circulation and structure exhibited planetary waves at various periods and revealed large semidiurnal tide amplitudes and variability with maximum amplitudes at higher altitudes often exceeding 60 m s 1 and amplitude modulations at periods from a few to 30 days

troposphere thermosphere tidal coupling as measured by the saber instrument on timed during july september 2002 1 coupling between the troposphere and lower thermosphere due to upward propagating tides is investigated using temperatures measured from the saber instrument on the timed satellite the data analyzed here are confined to 20 120 km altitude and 40 latitude during 20 july to 20 september 2002 apart from the migrating sun synchronous tidal components the predominant feature seen from the satellite frame during this period is a wave 4 structure in longitude with extrema of up to 40 50 k at 110 km amplitudes and longitudes of maxima of this structure evolve as the satellite precesses in local time and as the wave s responsible for this structure vary with time the primary wave responsible for the wave 4 pattern is the eastward propagating diurnal tide with zonal wave number s 3 de3 its average amplitude distribution over the interval is quasi symmetric about the equator similar to that of a kelvin wave with maximum of about 20 k at 5 s and 110 km de3 is primarily excited by latent heating due to deep tropical convection in the troposphere it is demonstrated that existence of de3 is intimately connected with the predominant wave 4 longitude distribution of topography and land sea difference at low latitudes and an analogy is drawn with the strong presence of de1 in mars atmosphere the predominant wave 2 topography on mars and the wave 2 patterns that dominate density measurements from the mars global surveyor mgs spacecraft near 130 km additional diurnal semidiurnal and terdiurnal nonmigrating tides are also revealed in the present study these tidal components are most likely excited by nonlinear interactions between their migrating counterparts and the stationary planetary wave with s 1 known to exist in the southern hemisphere during this period just prior to the austral midwinter stratospheric warming of 2002

diagenesis and reservoir quality of the sherwood sandstone triassic corrib field slyne basin west of ireland abstract the triassic sherwood sandstone in the corrib field slyne basin west of ireland on the european continental margin is a dry gas reservoir with a mercia mudstone top seal petrographic analysis combined with x ray diffraction stable isotope fluid inclusion and core analysis have been used to assess timing of growth and origin of mineral cements whether sandstone diagenesis involved mass flux the controls on reservoir quality and how reservoir quality is likely to vary in more deeply buried sections depositional and early diagenetic characteristics of the sherwood in corrib are typical of a semi arid fluvial environment containing groundwater of meteoric origin early diagenesis included the development of copious dolomite cement in the form of dolocrete as well as the formation of abundant clay while less volumetrically important grain coating haematite and k feldspar cement also grew burial diagenesis witnessed the initial growth of minor chlorite and albite quartz overgrowths and ankerite followed and are the most important burial cements growing over a temperature interval between 100 and 1165 c albite commenced growth at about 90 c quartz cement at 100 c and ankerite at 110 c these cements reached the zenith of their development at 105 110 c for albite 125 130 c for quartz and 135 145 c for ankerite siderite and anhydrite are relatively minor late stage cements the formation water has been consistently highly saline during burial and in terms of mineral cement derived oxygen stable isotope values is likely to be a diagenetically evolved version of the initial depositional water suggesting long term stagnation of the pore fluids the diagenetic reactions that formed burial cements all seem to be essentially isochemical including the ankerite that has carbon isotope characteristics of the cannibalisation of dolocrete reservoir quality is mainly controlled by early diagenetic dolomite and clay although grain size is also important because only sandstones with 200 m grain size have 50 md permeability both shallower and deeper sections than corrib may have similar porosity and permeability since temperature dependent diagenetic controls on reservoir quality e g quartz and illite cement are peripheral

tidal gravity wave interactions and their influence on the large scale dynamics of the middle atmosphere model results results from a modified version of the quasi geostrophic model of mclandress and mcfarlane 1993 in combination with the tidal model of forbes 1982a b are used to delineate the role of tides in modulating gravity wave momentum fluxes and the ensuing effects on the large scale circulation of the middle atmosphere for solstice conditions the influence of the tidal wind fields on the location and strength of the gravity wave drag is strongest in the mesosphere and lower thermosphere where the tidal winds are of the same order as the zonal mean component due to the nonlinear dependence on the local wind speed the daily mean gravity wave drag in the model can differ significantly depending on whether or not tidal variations are included at middle and low latitudes these differences are largest and occur as a result of the filtering effects of the shorter vertical wavelength diurnal tide at more polar latitudes where the longer wavelength semidiurnal tide dominates a slight increase in drag occurs the interaction between the tidal wind fields and the localized orographic gravity wave momentum flux has important consequences for the in situ generation of planetary scale disturbances in particular the amplification of stationary planetary wavenumber 1 is enhanced by the presence of tides in addition forcing of nonmigrating tidal modes is predicted to occur as a result of the localized drag

predictive permeability variations in a hermod sand reservoir stine segments siri field danish north sea abstract the hermod sand of the stine segments siri field danish north sea displays large permeability variations 1 600 md these permeability variations represent horizontal layering in the reservoir largely formed by diagenetic processes they have a significant impact on reservoir performance because horizontal producers in fairly thin reservoirs 30 m are protected against bottom water influx and can produce water free for long periods of time this paper presents the results of a detailed multidisciplinary study where the observed variation in permeability can be explained by two main diagenetic phases silica as opal cement and microquartz and berthierine a serpentine mineral that is closely related to chlorite opal microquartz and berthierine cements dominate in separate parts of the reservoir bodies opal microquartz cemented sands have high permeability typically 500 600 md berthierine cement has a different growth pattern in the oil and water zones resulting in intermediate permeability in the oil zone typically 50 100 md and very low permeability in the water zone typically 1 10 md

monthly tidal temperatures 20 120 km from timed saber 1 the saber instrument on the timed satellite provides unprecedented geographical coverage for the determination and study of atmospheric tides however the slow local time precession rate of timed can cause longer term temperature variations to alias into the tidal signals a new method of analyzing satellite data for tides has been developed to circumvent this difficulty but at the expense of temporal resolution of the tidal fields i e 120 day mean tidal structures are obtained in this work we apply this method to saber temperature data to derive a series of 120 day mean tidal structures extending between 20 and 120 km altitude 50 s 50 n latitude and centered on each month from september 2003 to september 2004 in addition to the migrating sun synchronous diurnal and semidiurnal tides a number of nonmigrating tides are revealed in the saber measurements some of these waves are thought to originate via nonlinear coupling between the migrating tides and the stationary planetary wave with zonal wave number s 1 other nonmigrating tidal components appear to be forced by latent heating due to deep tropical convection of the latter the eastward propagating diurnal tide with s 3 is dominant and is as large as the migrating diurnal tide during some months of particular interest is the wave 4 structure with respect to longitude that characterizes both the diurnal and semidiurnal total tidal fields this feature is a result of the predominant wave 4 topography land sea longitude dependence at the surface which is reflected in the diurnal and semidiurnal components of the latent heating rates due to deep tropical convection the ability of the global scale wave model gswm to approximate the observed tidal fields including the wave 4 total tidal structures is also assessed

diagenesis and reservoir quality evolution of palaeocene deep water marine sandstones the shetland faroes basin british continental shelf abstract the palaeocene deep water marine sandstones recovered from six wells in the shetland faroes basin represent lowstand transgressive and highstand systems tract turbiditic sediments mineralogic petrographic and geochemical analyses of these siliciclastics are used to decipher and discuss the diagenetic alterations and subsequent reservoir quality evolution the middle upper palaeocene sandstones subarkoses to arkoses from the shetland faroes basin british continental shelf are submarine turbiditic deposits that are cemented predominantly by carbonates quartz and clay minerals carbonate cements intergranular and grain replacive calcite siderite ferroan dolomite and ankerite are of eogenetic and mesogenetic origins the eogenetic alterations have been mediated by marine meteoric and mixed marine meteoric porewaters and resulted mainly in the precipitation of calcite 18 o v pdb 10 9 and 3 8 trace amounts of non ferroan dolomite siderite 18 o v pdb 14 4 to 0 6 as well as smectite and kaolinite in the lowstand systems tract lst and highstand systems tract hst turbiditic sandstone below the sequence boundary minor eogenetic siderite has precipitated between expanded and kaolinitized micas primarily biotite the mesogenetic alterations are interpreted to have been mediated by evolved marine porewaters and resulted in the precipitation of calcite 18 o v pdb 12 9 to 7 8 and fe dolomite ankerite 18 o v pdb 12 1 to 6 3 at temperatures of 50 140 and 60 140 c respectively quartz overgrowths and outgrowth which post and pre date the mesogenetic carbonate cements is more common in the lst and tst of distal turbiditic sandstone discrete quartz cement which is closely associated with illite and chlorite is the final diagenetic phase the clay minerals include intergranular and grain replacive eogenetic kaolinite smectite and mesogenetic illite and chlorite kaolinite has been subjected to mesogenetic replacement by dickite the k feldspar and plagioclase grains have been albitized dissolution of calcite cement and of framework grain feldspar volcanic fragments and mud intraclasts has resulted in a considerable enhancement of reservoir quality

origin of chlorite enrichment and neodymium isotopic anomalies in haltenbanken sandstones thisis really two papers rolled into one we have chosen to present them together because both topics derive from the same series of nd isotopic analyses of some chlorite coated jurassic age sandstone reservoirs from the norwegian continental shelf the first topic is a comparison of the nd isotopic composition of chlorite rich vs chlorite poor sandstones to determine whether systematic differences in sediment provenance have controlled the occurrence of grain coating fe chlorite cement the results show that both chlorite rich and chlorite poor sandstones have a wide range of 143nd 144nd consistent with mixing of at least two main provenance terranes of differing mean crustal age in both groups this does not support the model of chlorite enrichment due to localized influx of an unique fe rich provenance component such as mafic igneous material but is consistent with an alternative model of chlorite enrichment by fe clay authigenesis on the sea floor localized by fluvial discharge into a nearshore marine setting the implication is that studies of depositional setting rather than sand provenance should be the key to predicting occurrence and geometry of high porosity zones in deeply buried sandstones with chlorite related porosity preservation the second topic deriving from this set of nd isotopic data concerns the discovery of an association between anomalously high smnd model ages and elevated contents of bulk rock phosphorous this sub set of the samples is anomalous in that the smnd model ages are too high to be interpreted as detrital provenance ages and also because smnd model age correlates with sm nd ratio furthermore the anomalous smnd signature can be removed by acid leaching leaving a residue with apparently non anomalous smnd characteristics analysis of an apatite mineral separate from one sample confirms that the anomalous smnd signature resides within diagenetic apatite the anomalies are suggested to result from ree fractionation due to the crystal chemistry of apatite which favors preferential incorporation of the intermediate weight ree thus increasing sm nd and smnd model age the apatite probably formed by recrystallization of phosphate that was present at the time of sand deposition either as organic detritus or as the product of precipitation on the sea floor the isotopic composition of the apatite indicates that sm nd fractionation occurred within the past 100 million years and thus was not syndepositional formation of the nd isotopic anomalies is therefore interpreted to be a burial diagenetic process involving local ree enrichment of apatite and complementary ree depletion of the surrounding rock mass experimental apatite melt partition coe cients determined at magmatic temperatures predict much lower sm nd fractionation than is observed in the present samples but we speculate that the degree of fractionation may increase greatly toward the lower diagenetic temperatures relevant for the present samples the discovery of these anomalies does not invalidate the use of smnd model age profiling as a stratigraphic correlation tool and provenance indicator but indicates that precautions should be taken when dealing with marine sandstones specifically data sets should be examined for correlation between smnd model age and sm nd ratio which may indicate the presence of anomalous fractionation effects even in such cases the isotopic ratio 143nd 144nd can provide a reliable provenance signature 1998 elsevier science ltd all rights reserved

sources of nonmigrating tides in the tropical middle atmosphere 1 temperature measurements from the cryogenic infrared spectrometers and telescopes for the atmosphere crista experiment taken during the u s space shuttle mission sts 66 in november 1994 provide a variety of zonally symmetric and asymmetric tidal signatures in the altitude range from 40 90 km the most prominent zonally asymmetric tidal pattern is identified to be the westward propagating nonmigrating diurnal tide of zonal wavenumber 2 s 2 this mode has an amplitude of approximately half the amplitude of the migrating s 1 component of the diurnal tide the observational findings are compared to model results from the global scale wave model gswm and from the thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm gswm and time gcm account for different tidal sources and therefore allow an analysis of the tidal forcing responsible for the observed signatures the gswm tidal forcing in the model version used is based upon latent heat release associated with tropical deep convection while nonmigrating tides in the time gcm are predominantly forced by nonlinear interactions between the migrating diurnal tide and stationary planetary waves it is shown that the latter mechanism forces a large part of the s 2 mode while the stationary zonally uniform s 0 diurnal nonmigrating tide is mainly driven by latent heat release this result suggests that dynamical models for the mesosphere lower thermosphere mlt region need to account for the tropospheric latent heat source and stationary planetary wave activity in order to predict realistic longitudinal diurnal tidal variability

lithologic characteristics and diagenesis of the devonian jauf sandstone at ghawar field eastern saudi arabia abstract the lower devonian jauf formation in saudi arabia is an important hydrocarbon reservoir however in spite of its importance as a reservoir published studies on the jauf formation more specifically on the reservoir quality including diagenesis are very few this study which is based on core samples from two wells in the ghawar field northeastern saudi arabia reports the lithologic and diagenetic characteristics of this reservoir the jauf reservoir is a fine to medium grained moderate to well sorted quartz arenite the diagenetic processes recognized include compaction cementation calcite clay minerals quartz overgrowths and a minor amount of pyrite and dissolution of the calcite cements and of feldspar grains the widespread occurrences of early calcite cement suggest that the jauf reservoir lost a significant amount of primary porosity at a very early stage of its diagenetic history early calcite cement however prevented the later compaction of the sandstone thus preserving an unfilled part of the primary porosity based on the framework grain cement relationships precipitation of the early calcite cement was either accompanied or followed by the development of part of the pore lining and pore bridging clay cement secondary porosity development occurred due to partial to complete dissolution of early calcite cements and feldspar late calcite cement occurs as isolated patches and has little impact on reservoir quality of the sandstones in addition to calcite several different clay minerals including illite and chlorite occur as pore filling and pore lining cements while the pore filling illite and chlorite resulted in a considerable loss of porosity the pore lining chlorite may have helped in retaining the porosity by preventing the precipitation of syntaxial quartz overgrowths illite which largely occurs as hair like rims around the grains and bridges on the pore throats caused a substantial deterioration to permeability of the reservoir diagenetic history of the jauf formation as established here is expected to help better understanding and exploitation of this reservoir

tephra stratification of volcanic ash soils in northern ecuador we combined proxies traditionally used in stratigraphic research mineral assemblages grain size distribution and element ratios with soil organic carbon contents and radiocarbon dating both at a high vertical resolution to unravel the tephra stratigraphy in volcanic ash soils our results show that soil profiles along an altitudinal transect intersecting the upper forest line in northern ecuador were formed in three distinct tephra deposits although the deposits contained a similar assemblage of minerals we were able to differentiate these deposits because of their characteristic organic carbon distribution grain size distribution and typical sro to na2o cao and crystalline al2o3 ratios unravelling the tephra stratigraphy improved understanding of the vertical distribution of soil organic carbon including paleoecological proxies in the studied soils we demonstrated that bioturbation likely plays an important role in current pedogenesis resulting in overprinting merging mixing of the paleosol surprisingly in spite of bioturbation a linear age depth relationship exists leading to the hypothesis that the active zone of bioturbation shifted upwards during soil formation therefore we conclude that paleoecological proxies are stratified in our soils albeit probably somewhat more crudely than in undisturbed peat bogs or lake sediments

phanerozoic oolitic ironstones geologic record and facies model oolitic ironstonesl composed predominantly of ooidsl of ferric oxide and chamosite accumulated throughout much of phanerozoic time figure 1 and some of them have been important ore deposits they are built of two very common products of weathering iron oxide and clay but they constitute a distinctive and subordinate sedimentary facies for which there is no simple modem analogue as a result considerable disagreement has attended more than 125 years of discussion about their origin early analyses of these rocks for example the minette are of france focused mainly on their chemical and mineral composition and on processes of diagenesis more recent work has described their sedimentary textures and structures as well as their general facies and depositional environments ad eleye 1973 brookfield 1973 corbin 1980 hallam 1975 karpov et a11967

diagenesis and reservoir quality of bhuban sandstones neogene titas gas field bengal basin bangladesh abstract this study deals with the diagenesis and reservoir quality of sandstones of the bhuban formation located at the titas gas field of bengal basin petrographic study including xrd cl sem and bse image analysis and quantitative determination of reservoir properties were carried out for this study the sandstones are fine to medium grained moderately well to well sorted subfeldspathic arenites with subordinate feldspathic and lithic arenites the diagenetic processes include clay infiltration compaction and cementation quartz overgrowth chlorite kaolinite calcite and minor amount of pyrite dolomite and k feldspar overgrowth quartz is the dominant pore occluding cement and generally occurred as small euhedral crystals locally as large pyramidal crystals in the primary pores pressure solution derived from grain contact is the main contributor of quartz overgrowths chlorite occurs as pore lining and pore filling cement in some cases chlorite helps to retain porosity by preventing quartz overgrowth in some restricted depth interval pore occlusion by calcite cement is very much intense kaolinite locally developed as vermiform and accelerated the minor porosity loss due to pore occlusion kaolinite chlorite enhances ineffective microporosity kaolinite is a by product of feldspar leaching in the presence of acidic fluid produced during the maturation of organic matter in the adjacent miocene or deeper oligocene source rocks the relation between diagenesis and reservoir quality is as follows the initial porosity was decreased by compaction and cementation and then increased by leaching of the metastable grains and dissolution of cement good quality reservoir rocks were deposited in fluvial environment and hence quality of reservoir rocks is also environment selective porosity and permeability data exhibit good inverse correlation with cement however some data points indicate multiple controls on permeability reservoir quality is thus controlled by pore occluding cement textural parameters grain size pore size and sorting and depositional environment the reservoir finally resumed partly its pre cementation quality after development of secondary porosity

early palaeozoic brachiopods and associated shelly faunas from western gondwana their bearing on the geodynamic history of the pre andean margin

pre requisites processes and prediction of chlorite grain coatings in petroleum reservoirs a review of subsurface examples abstract deeply buried reservoirs containing chlorite coated quartz sand grains commonly have higher than expected porosity and permeability although prediction of such positive anomalies still remains elusive a total of 54 published examples based on information and data from 62 scientific papers was collated quantification of some of the most common parameters including depositional environment age and latitude of sand deposition effect on reservoir quality and chemical composition of chlorite is presented the dataset indicates that chlorite coats are found in sandstones deposited in a range of depositional environments but most commonly occur in delta related environments 44 with fluvial environments the second most common 19 age relationships indicate that there is an overall exploration bias in published examples with chlorite coats becoming increasingly common through time the latitude at the time of deposition of sands with chlorite coats is wide 60 n 60 s and indicates that temperate and tropical climates are important for the generation of this clay mineral chlorite can have a variable effect on reservoir quality but is typically positive iron rich chlorites occur overwhelmingly in coastal environments while mixed iron and magnesium rich chlorites are principally found in marine and terrestrial sandstones analysis of these factors suggests that hinterland geology basinal soil development and geochemical weathering and proximity to river systems are essential to the formation of chlorite precursor phases these characteristics have been combined to define situations where chlorite coats were more likely or more unlikely to form these parameters will provide insights into the formation of chlorite and to further refine predictive models for the presence or absence of chlorite coated sandstones

all age depth models are wrong but how badly the uncertainty and error associated with fitted age depth models were investigated by fitting a range of models to sets of simulated radiocarbon dates based on varved sediments and comparing the modelled relationship with the varve timescale with large numbers of dates cubic smooth splines out perform other models with few dates no model reliably provides a good fit to reality and calculated confidence intervals are over optimistic c 2003 elsevier ltd all rights reserved

holocene palaeofires in neotropics high mountains the contribution of soil charcoal analysis abstract the holocene palaeofires in southern america has been generally attributed to climate until the middle holocene and to human activities for later periods soil charcoal analysis and extensive ams dating were carried out on six soil profiles between 3400 and 3900 m a s l in the guandera biological reserve western cordillera real north ecuador ams results showed an ordered stratification of charcoals allowing a fire history reconstruction over the last 11 700 cal bp the reported fire occurrences fit well with holocene global scale arid periods the association between fires and climate signals suggested a marginal role of humans in the environmental history of the studied area here the human inference started at ca 2500 cal bp but became considerable only in the last millennium

atmospheric tide 2 the solar and lunar semidiurnal components solar and lunar semidiurnal wind and temperature oscillations from the surface to 400 km are simulated for average solar activity conditions utilizing the numerical tidal model described in part 1 hough mode decomposition of the solstitial solar semidiurnal tide excited by h2o and o3 insolation absorption below 80 km indicates that it is characterized by a predominance of 2 2 below 60 km about equal contributions of 2 2 2 3 and 2 4 between 70 and 90 km mostly 2 4 with some 2 5 and 2 2 between 90 and 120 km and a predominance of 2 2 above 140 km with secondary contributions from 2 3 and 2 5 the solstitial lunar semidiurnal tide is characterized by a predominance of 2 2 below 70 km 2 4 with secondary contributions from 2 2 2 3 and 2 5 between 80 and 110 km and by 2 2 with a fairly strong secondary contribution from 2 3 above 120 km similar descriptions for both the solar and lunar oscillations apply at equinox except that the asymmetric 2 3 and 2 5 modes are absent relative to the solar component lunar temperature and wind amplitudes are sufficiently large 20 in the lower and upper thermosphere to account for some of the observed variability previously attributed to the solar tide amplitudes of the 2 4 and 2 5 modes above 100 km are significantly affected by mesospheric eddy diffusion coefficients in excess of 2 106 cm s 1 the total solar semidiurnal exospheric temperature oscillation for average solar conditions ranges from 10 20 k poleward of 40 n to 40 60 k equatorward of 30 n and has its origin in three sources of excitation all of comparable importance 1 euv solar radiation absorption in the lower thermosphere 100 200 km 2 in situ momentum coupling due to the interaction of diurnal winds and diurnally varying ion drag and 3 tides propagating upwards from below 100 km in addition the calculations are compared with rocket meteor radar partial reflection thomson scatter and satellite data to evaluate the consistency of the model with observations

an isochemical model for formation of authigenic kaolinite k feldspar and illite in sediments abstract although thermodynamic calculations indicate a narrow range of conditions for coprecipitation of kaolinite and k feldspar coexistence of authigenic kaolinite and k feldspar is common in jurassic sandstones of the north sea this paper shows that the coexistence of authigenic k feldspar and kaolinite may indicate that this narrow range of conditions did prevail and that the system behaved as a closed system these conditions are presence of muscovite in the sediment pore waters supersaturated with respect to quartz and temperatures lower than 50 c at higher temperatures the authigenic kaolinite and authigenic k feldspar may react and form authigenic illite muscovite and quartz cement the direction of the isochemical reaction is thermodynamically determined by the degree of supersaturation with respect to quartz in the formation water published data on the degree of supersaturation with respect to quartz in formation waters suggest that the illitization of kaolinite may take place at temperatures as low as 50 c much lower than previously believed

satellite observations of thermospheric tides results from the wind imaging interferometer on uars thermospheric winds measured by the wind imaging interferometer windii on the upper atmosphere research satellite are analyzed for migrating solar tides the data cover a 2 year period commencing february 1992 and are obtained from the atomic oxygen o 1s 557 7 nm emission which provides observations of the 90 to 200 km altitude range during daytime and the 90 to 110 km range at night the subtropical lower thermosphere is dominated by the diurnal propagating tide which exhibits a vertical wavelength of approximately 22 km grows in amplitude up to 95 km and decays rapidly above where molecular diffusion greatly reduces the vertical shears although the phase remains fairly uniform throughout the year a pronounced semiannual oscillation is observed in the diurnal tide amplitude at both 20 n and 20 s the meridional and zonal wind components attain their maximum values at equinox of approximately 70 and 40 m s respectively while the solstitial minima are nearly a factor of 2 smaller at 35 n the diurnal tide semiannual amplitude oscillation is still present in the lower thermosphere but above 100 km it is replaced by an annual cycle with a maximum in july and august this contrasts with 35 s where the july august peak is absent and the semiannual oscillation extends to 110 km at midlatitudes the zonal and meridional winds are of similar magnitude and no significant hemispheric asymmetries in amplitudes are observed in the lower thermosphere the semidiurnal tide amplitude exhibits an annual oscillation with maximum values of 30 to 40 m s occurring in june july near 100 km at 35 n 35 s and the equator a bimodal structure in the seasonal variation of the semidiurnal phase is observed this feature is characterized by rapid equinoctial transitions and is particularly well defined at the equator examination of the equatorial middle thermosphere indicates that the semidiurnal tide attains its maximum amplitude at 140 km and exhibits a vertical wavelength of approximately 60 km these findings indicate the predominance of the antisymmetric 2 3 hough mode in the tropics

selective alteration of arkose framework in oligo miocene turbidites of the northern apennines foreland impact on sedimentary provenance analysis

from a black to a gray box a mass balance interpretation of pedogenesis we utilize chemical elements as tracers in a mass balance analysis that provides functional relationships among soil chemical composition bulk density and volume change in relation to parent material these analytical functions are based on the principle of conservation of mass and include a term quantifying mass flux into out of the soil and between horizons we apply the technique to the oldest member of a chronosequence developed on marine terraces in northern california it is an alfisol that evolved from beach sand to its present state nearly one third of its weight is composed of secondary clay minerals in about 240 ky aside from large increases in organic carbon desilication is the dominant factor in soil evolution 29 50 83 g cm 2 si was leached from the beach sand during pedogenesis the rate of desilication is roughly 2 1 t km 2 yr 1 0 21 g cm 2 ky 1 an order of magnitude slower than that implied by the si denudation rate calculated for the mattole river watershed weathering of primary minerals and synthesis of secondary minerals is relatively well advanced suggesting that the rate of desilication may be declining the local beach is composed of quartz and sodic plagioclase with smaller amounts of chlorite mica and kaolinite the soil has substantially different mineralogy sand is dominated by quartz and clay is dominated by kaolinite halloysite chloritic intergrades and gibbsite bases are also leached though the total mass was much less 57 2 55 g cm 2 of na in the beach sand was lost as plagioclase weathered by focusing on elemental and mineralogical gains and losses we emphasize the essential connection between the pedologic environment and the external hydrochemical environment

the cultural nature of tephra problematic ecofacts and artifacts and the baru volcano panama abstract this paper presents data from archaeological stratigraphy and lacustrine core samples containing tephra from the baru volcano in western panama the discussion seeks to refine the understanding of medial tephra deposits near baru in relation to the eruption history indicated by geological palaeoecological and archaeological data a primary goal of this fieldwork is the identification and correlation of tephra from major baru eruptions encountered in archaeological contexts by their lithology stratigraphic position and mineralogy without resorting to geochemical fingerprinting the intention is to develop a cost efficient and reproducible means of utilizing tephra as a chronostratigraphic marker in archaeological contexts and examine the intersection of human life with volcanic events and dynamic environments tephra in archaeological contexts can have ambiguous placement between ecofact and artifact as is the case with a small number of crude tephra sculptures in my excavated material and that of a seminal prior study while the research project utilizes visible tephra layers not cryptotephra by all means the tephra data prove to be cryptic engagement with the imperfection entailed in meshing multidisciplinary data sets and different scientific communities with interests in tephra particularly in lesser studied regions is posited as a total view of tephra

original sediment composition of the lower cretaceous lacustrine tight oil mudstone and influences on diagenesis and organic matter content the erennaoer sag in erlian basin ne china abstract the original sediment composition is of great value to providing an understanding of depositional environment and hydrocarbon generation potential but it is easily altered by diagenesis and difficult to recognize in this study we examine carbonate rich tight oil mudstones of the lower cretaceous arshan formation in the erennaoer sag of the erlian basin as an example based on analyses of mineralogy stable carbon and oxygen isotopes and trace rare earth elements the original composition of the arshan mudstones has been reconstructed results show that the original arshan mudstone composition was mainly siliciclastic detritus tuffaceous and clay matrix which has a major impact on diagenesis and organic matter content the erupted volcanic ashes were beneficial to the introduction of nutrients an increase in biomass and an associated increase in to the preservation of organic matter which has been suggested by an improvement of toc of arshan tuffaceous mudstones with average contents of 2 82 the volcanic ashes in the studied mudstones had also enhanced methanogensis during the shallow burial additionally the early alteration products of authigenic minerals include analcime or zeolite most of which is entirely altered to analcime and chlorite the formation of major eogenetic carbonate cements include early dolomite and calcite which were related to volcanic materials and methanogenesis at shallow depths

drake antarctic agile meteor radar first results configuration and comparison of mean and tidal wind and gravity wave momentum flux measurements with southern argentina agile meteor radar 1 a new generation meteor radar was installed at the brazilian antarctic comandante ferraz base 62 1 s in march 2010 this paper describes the motivations for the radar location its measurement capabilities and comparisons of measured mean winds tides and gravity wave momentum fluxes from april to june of 2010 and 2011 with those by a similar radar on tierra del fuego 53 8 s motivations for the radars include the hotspot of small scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere mlt centered over the drake passage the maximum of the semidiurnal tide at these latitudes and the lack of other mlt wind measurements in this latitude band mean winds are seen to be strongly modulated at planetary wave and longer periods and to exhibit strong coherence over the two radars at shorter time scales as well as systematic seasonal variations the semidiurnal tide contributes most to the large scale winds over both radars with maximum tidal amplitudes during may and maxima at the highest altitudes varying from 20 to 70 ms 1 in contrast the diurnal tide and various planetary waves achieve maximum winds of 10 to 20 ms 1 monthly mean gravity wave momentum fluxes appear to reflect the occurrence of significant sources at lower altitudes with relatively small zonal fluxes over both radars but with significant and opposite meridional momentum fluxes below 85 km these suggest gravity waves propagating away from the drake passage at both sites and may indicate an important source region accounting in part for this hotspot

reconstruction of late holocene forest dynamics in northern ecuador from biomarkers and pollen in soil cores centuries of human interference have led to large scale reduction of montane forests in the northern ecuadorian andes as a result the natural position of the upper forest line ufl in the area is now subject of scientific debate which is hindering sustainable reforestation efforts uncertainty is fuelled by insufficient precision of fossil pollen spectra to reconstruct the natural ufl position here we tried to resolve this issue by using biomarkers i e plant species specific patterns of n alkanes and n alcohols preserved in soils in the northern ecuadorian andes as additional proxy to reconstruct the natural ufl position to unravel preserved biomarker patterns we used the recently developed verhib model and for the first time assessed its applicability in soil archives changes in holocene biomarker based vegetation composition were directly compared to changes in pollen based vegetation composition from the same soil profiles both proxies proved to be complementary and a combined application allowed for a more accurate reconstruction of past vegetation than with pollen analysis alone we found that the present day ufl in the study area has not been significantly depressed by human interference and was at 3650 m maximally during late holocene times for the moment of post glacial forest development we found a migration lag between pollen earlier and biomarkers later this reflects the difference between the non transported biomarker signal showing spot dating thus in paleoecological studies functionally equalling the information from plant macro remains in peat bogs and the upslope wind blown pollen signal showing an upslope forest expansion up to over a millennium ahead the combined pollen biomarker approach in soil cores shows great potential for vegetation reconstruction however more research of biomarker consistency and preservation is needed before application in other environments

highly localized cooling in daytime mesopause temperature over the dip equator during counter electrojet events first results the first observations of lowering of mesopause temperature during counter electrojet cej events over a narrow region of 150 km centered at around magnetic equator are presented the daytime mesopause temperature is measured over trivandrum 8 5 n 77 e dip lat 0 5 n india using the ground based multiwavelength dayglow photometer the unique meridional scanning capability of the instrument is extensively used in this study a lowering of temperature by as much as 25 k has been observed during certain cej events which includes a few partial cejs the gravity wave tidal interaction through vertically upward wind is proposed to be manifesting as lowering in the mesopause temperature and also as cej these observations are new and address to the issues concerning the vertical coupling processes prevailing in the equatorial mesosphere lower thermosphere ionosphere mlti region citation vineeth c t k pant c v devasia and r sridharan 2007 highly localized cooling in daytime mesopause temperature over the dip equator during counter electrojet events

controls on diagenesis of lower cretaceous reservoir sandstones in the western sable subbasin offshore nova scotia abstract lower cretaceous deltaic sandstones of the scotian basin offshore eastern canada are important gas reservoirs the influence of several factors on diagenesis has been investigated depositional lithofacies sea level changes chemistry of basinal sediments and basinal fluid flux during burial the distribution and chemistry of diagenetic minerals was determined from nine wells located along a dip section of the sable subbasin mineral type and paragenesis were characterized using a combination of optical petrography back scattered electron images and electron microprobe analyses siderite is unusually abundant in marine sediments of the scotian basin and has thus been studied in detail siderite occurs in several generations early and late siderites are similar in chemical composition suggesting buffering by pre existing siderite but rare low mg siderite is related to a greater contribution of meteoric water siderite has locally dissolved to create microporosity and has suppressed quartz overgrowths siderite is most common in those muddy prodeltaic lithofacies where there is the highest availability of detrital ilmenite reactive fe released by breakdown of this ilmenite is responsible for the unusual presence of early siderite in marine sediments with the ca and mg content of the siderite indicating fully marine waters lithofacies have a strong influence on early diagenetic mineral assemblages lithofacies deposited in the transgressive system tract have abundant early fe calcite and siderite early kaolinite occurs principally in proximal fluvial and river mouth lithofacies where meteoric water was most likely available during the deposition contrary to other studies we find little impact of sequence stratigraphy on diagenetic minerals except in the transgressive system tract mesogenetic minerals are related to flux of formation water and maturing hydrocarbon products resulting first in pyrite and siderite and later in ankerite and ferroan calcite the principal controls are interpreted to be high fe 2 and low ca 2 of formation waters and vertical movement of the waters along faults overall the bulk chemical composition of terrigenous sediments and the depositional lithofacies are the most important factors controlling diagenetic minerals in the lower cretaceous of the scotian basin

geochemical evolution of pore waters in the rotliegend early permian of northern germany abstract the distribution of early cements within permian rotliegend sandstones closely resembles cementation patterns within modern playa lake basins the isotopic compositions of eogenetic cements in the thick rotliegend sequence of germany show continental signatures typical of minerals precipitated in such an environment carbon sulphur and strontium isotopic ratios of many rotliegend cements which formed during burial suggest formation from a mixture of rotliegend fluids and waters from the overlying zechstein evaporites a two component mixing model for the evolution of rotliegend pore waters indicates that the isotopic signatures in these cements may result from the introduction of only minor amounts of zechstein fluid

experimental simulation of clay precipitation within reservoir sandstones 2 mechanism of illite formation and controls on morphology illite and illite smectite with various morphologies have been formed on quartz grains by precipitation from solution following dissolution of amorphous al si gels at 150 350 degrees c and 0 75 1 0 kbar 75 100 mpa initial solutions include deionized water chloride and oxalate the experimental results have application to the formation of authigenic illite in sandstones from pore waters containing carboxylic acid anions a series of experiments monitored the effects of reaction temperature and time on the composition and morphology of illitic minerals precipitated following the dissolution of an amorphous gel of illite composition in deionized water a progressive increase of 70 to 100 in the illite content of illite smectite occurs between 150 and 350 degrees c but there is no change in illite smectite composition for reaction times of 24 hours to 37 days these results indicate that illite and illite rich illite smectite form by direct precipitation from solution and do not require a smectitic precursor the compositional variation in illite smectite and illite has little or no effect on clay morphology all experiments produced a platy boxwork morphology experiments performed at 250 degrees c and initially containing oxalate in both acidic and alkaline k bearing solutions strongly promote illite precipitation following the dissolution of an amorphous al si oxide starting material the very rapid precipitation that occurs under these conditions is associated with the formation of fibrous lath type illites rather than platy types which are characteristic of slower precipitation in the absence of oxalate precipitation of fibrous illite is related to the breakdown of oxalate which lowers illite solubility by either ph variation or by breakdown of an al oxalate complex oxalate is not a direct requirement for fibrous illite formation although it controls fluid composition which favors fibrous illite formation the association of illite precipitation with carboxylate anion breakdown suggests that the formation of fibrous illite cements in petroleum reservoirs is related to fluids released from source rocks which contain both aqueous organic acids and inorganic solutes

the holocene treeline in the northern andes ecuador first evidence from soil charcoal abstract indications for the speed and timing of past altitudinal treeline shifts are often contradictory partly this may be due to interpretation difficulties of pollen records which are generally regional rather than local proxies we used pedoanthracology the identification and dating of macroscopic soil charcoal to study vegetation history around the treeline in the northern ecuadorian andes pedoanthracology offers a complementary method to pollen based vegetation reconstructions by providing records with high spatial detail on a local scale the modern vegetation is tussock grass paramo tropical alpine vegetation and upper montane cloud forest and the treeline is located at ca 3600 m charcoal was collected from soils in the paramo at 3890 and 3810 m and in the forest at 3540 m and represents a sequence for the entire holocene the presence of paramo taxa throughout all three soil profiles especially in combination with the absence of forest taxa shows that the treeline in the study area has moved up to its present position only late in the holocene after ca 5850 cal years bp the treeline may have been situated between 3600 m and 3800 m at some time after ca 4900 cal years bp or it may never have been higher than it is today the presence of charcoal throughout the profiles also shows that fires have occurred in this area at least since the beginning of the holocene these results contradict interpretations of palaeological data from colombia which suggest a rapid treeline rise at the pleistocene holocene transition they also contradict the hypothesis that man made fires have destroyed large extents of forest above the modern treeline instead paramo fires have probably contributed to the slowness of treeline rise during the holocene