zeolites in burial diagenesis and low grade metamorphic rocks many zeolite assemblages originated during burial and subsequent low grade metamorphism of rocks particularly those of volcaniclastic origin eskola 1939 first suggested this type of zeolitization and applied the term zeolite facies to assemblages formed under such low temperature and low pressure conditions although several definitions of the zeolite facies have been proposed over the years e g fyfe et al 1958 the phrase as used here includes both low grade metamorphic assemblages and zeolite assemblages formed successively during burial the regional occurrence of zeolites in sedimentary rocks was first recognized by coombs 1954 who made detailed petrographic studies of triassic tuffaceous greywackes and tuffs of andesitic to rhyolitic in composition in the taringatura area of new zealand coombs recognized a zonal arrangement of heulandite and analcime near the top of the sequence and heulandite and laumontite near the bottom he also recognized a similar progressive zeolitization with depth in clastic sediments in other orogenic belts the zeolite assemblages described by coombs represent a rather advanced stage of alteration as opposed to an earlier stage of zeolitization that was subsequently described in neogene silicic volcaniclastic rocks from japan in the latter rocks zones from top to bottom of fresh glass clinoptilolite mordenite analcime heulandite laumontite and albite were recognized utada 1965 1970 progressive zeolitization has also been reported as a result of the thermal effects of intrusive masses see seki et al 1969 and around volcanic calderas utada and ito 1989 recently boles 1991 described the low temperature formation of laumontite and stilbite in fractures and faults related to post jurassic folding and uplift of the southland syncline new zealand the physico chemical conditions of zeolite crystallization in burial diagenesis and low grade metamorphic environments can vary widely both borehole data see iijima 1995 and experimental results liou 1970 1971a b c

how are large western hemisphere warm pools formed during the boreal summer the western hemisphere warm pool whwp stretches from the eastern north pacific to the tropical north atlantic and is a key feature of the climate of the americas and africa in the summers following nine el nino events during 1950 2000 there have been five instances of extraordinarily large warm pools averaging about twice the climatological annual size these large warm pools have induced a strengthened divergent circulation aloft and have been associated with rainfall anomalies throughout the western hemisphere tropics and subtropics and with more frequent hurricanes however following four other el nino events large warm pools did not develop such that the mere existence of el nino during the boreal winter does not provide the basis for predicting an anomalously large warm pool the follow ing summer in this paper we find consistency with the hypothesis that large warm pools result from an anomalous divergent cir culation forced by sea surface temperature sst anomalies in the pacific the so called atmospheric bridge we also find significant explanations for why large warm pools do not always develop if the el nino event ends early in the eastern pacific the pacific warm anomaly lacks the persistence needed to force the atmospheric bridge and the atlantic portion of the warm pool remains normal if sst anomalies in the eastern pacific do not last much beyond february of the fol lowing year then the eastern north pacific portion of the warm pool remains normal the overall strength of the pacific el nino does not appear to be a critical factor we also find that when conditions favor a developing atmospheric bridge and the winter atmosphere over the north atlantic conforms to a negative north atlantic oscillation nao pattern as in 1957 58 and 1968 69 the forcing is reinforced and the warm pool is stronger on the other hand if a positive nao pat tern develops the warm pool may remain normal even if other circumstances favor the atmospheric bridge as in 1991 92 finally we could find little evidence that interactions internal to the tropical atlantic are likely to mitigate for or against the formation of the largest warm pools although they may affect smaller warm pool fluctuations or the warm pool persistence

hump shaped 40ar 39ar age spectra in k feldspar and evidence for cretaceous authigenesis in the fountain formation near eldorado springs colorado the fountain formation near eldorado springs co usa shows evidence of alteration by hydrothermal fluids that precipitated authigenic potassium feldspar adularia as rims on detrital feldspars and as interstitial cement deposits detailed 40ar 39ar step heating experiments of samples from the fountain formation reveal age spectra having a characteristic hump at laboratory temperatures between 900 and 1080 c the humps appear to be related to the presence of adularia laser analyses of small grains of adularia indicate that the hump can be physically dissected unlike age gradients found in igneous feldspars such behavior is consistent with the mixing of gas from two or more generations of k feldspar each having unique diffusion properties the feldspars studied here indicate that two pulses of 150 c hydrothermal fluids migrated through the fountain formation at 135 and 94 ma prior to the main phase of laramide tectonic activity in the region the limited occurrence of authigenic cements suggests that reactivation of the underlying precambrian idaho springs ralston creek shear zone was significant enough to heat and mobilize large quantities of meteoric fluids in addition these data also suggest that cretaceous movements along the transcontinental arch correlated with stratigraphic events began approximately 40 million years earlier than previously thought

a large amplitude gravity wave in the lower stratosphere detected by radiosonde temperature profiles in the lower stratosphere commonly show fluctuations typical peak to peak amplitude of a few degrees on a vertical scale of a few kilometres the routine operational radiosonde launched from shanwell 56 43 n 2 87 w at 2318 gmt on 12 december 1986 recorded very large amplitude excursions in temperature 15 9 k change over a vertical distance of 2 km in the lower stratosphere which were identified as being exceptional by the staff at the radiosonde station the temperature fluctuations were accompanied by strong shear in the horizontal wind and large variations in the rate of ascent of the balloon the disturbance is argued to be due to a quasi stationary gravity wave with vertical momentum flux about 3 or 4 n m 2 averaged over a horizontal scale of at least 20km these observations their meteorological context and their interpretation are described in detail

gravity waves above the andes detected from gps radio occultation temperature profiles jet mechanism 1 a significant wave activity wa in the upper troposphere and lower stratosphere mainly during winter was detected at midlatitudes in the southern hemisphere 30 40s above the andes range from an analysis of global positioning system radio occultation gps ro temperature profiles retrieved by champ challenging minisatellite payload and sac c satelite de aplicaciones cientificas c low earth orbit leo satellites between may 2001 and february 2006 the possible main gravity wave sources in this region are i orographic forcing ii geostrophic adjustment and iii deep convection the available vertical resolution of gps ro soundings does not rule out any of these alternatives based on satellite imaginary the wa enhancements cannot be attributed to deep convection events inertia gravity waves igws could be generated after a geostrophic adjustment process following a perturbation of the zonal jet situated above the andes mountains by mountain waves mws the monthly wa intensity follows the zonal wind velocity strength according to its seasonal variability at jet altitudes as the gps leo lines of sight are roughly meridionally aligned and the morphology of the andes at middle latitudes is predominantly north south it was possible to detect mws as well as igws from gps ro temperature profiles this characteristic does not apply for other mountain range alignments from the analysis of a numerical simulation at the time and location of a single ro event with very strong wa two main modes of oscillation with horizontal wavelength around 40 and 200 km were identified the first one is attributed to a mw and the second one to an igw

sequence stratigraphy of continental triassic strata of southernmost brazil a contribution to southwestern gondwana palaeogeography and palaeoclimate abstract the continental triassic succession of southernmost brazil comprises two second order depositional sequences the sanga do cabral early triassic and the santa maria middle to late triassic supersequences the first one includes ephemeral low sinuosity fluvial deposits developed on a low gradient plain based on fossil tetrapods especially procolophonids an upper induan age is estimated for this sequence facies association of the santa maria supersequence indicates low sinuosity fluvial rivers deltas and lakes this supersequence can be further subdivided into three third order sequences age provided by palaeovertebrate biostratigraphic data as follows santa maria 1 ladinian santa maria 2 carnian to early norian and santa maria 3 probably raethian or early jurassic sequences the gondwanides paroxysms i and ii in the sierra de la ventana cape fold belt are directly related to the development of both supersequences the source area of the sanga do cabral supersequence was located to the south it consisted of an uplifted peripheral bulge situated landward of the retro foreland system from where older sedimentary rocks were eroded the source area of the santa maria supersequence was also positioned southwards and related to the uplifted sul rio grandense and uruguayan shields the santa maria supersequence stratigraphic architecture is comparable to the triassic rift basins of western argentina diagenesis facies and palaeontology of the studied succession suggest a dominantly semiarid climate during the triassic

evidence of gravity wave saturation and local turbulence production in the summer mesosphere and lower thermosphere during the state experiment this study utilizes the unique data set obtained during the structure and atmospheric turbulence environment state experiment conducted during june 1983 at poker flat alaska to examine the structure and characteristics of the wave field near the summer mesopause it is shown that the rocket and radar data together permit a much more detailed specification of wave parameters than would be possible using either data set alone the results of this analysis suggest that the wave field near the summer mesopause is composed in general of a superposition of wave motions which act collectively to produce regions in which the wave field is convectively or dynamically unstable these regions are found to correlate well with zones of enhanced turbulence and small scale wave activity suggesting the processes and effects of wave field saturation

the triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology abstract the triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology divides triassic time into eight land vertebrate faunachrons lvfs with boundaries defined by the first appearance datums fads of tetrapod genera or in two cases the fads of a tetrapod species definition and characterization of these lvfs is updated here as follows the beginning of the lootsbergian lvf fad of lystrosaurus the beginning of the nonesian fad cynognathus the beginning of the perovkan lvf fad eocyclotosaurus the beginning of the berdyankian lvf fad mastodonsaurus giganteus the beginning of the otischalkian lvf fad parasuchus the beginning of the adamanian lvf fad rutiodon the beginning of the revueltian lvf fad typothorax coccinarum and the beginning of the apachean lvf fad redondasaurus the end of the apachean beginning of the wasonian lvf near the beginning of the jurassic is the fad of the crocodylomorph protosuchus the early triassic tetrapod lvfs lootsbergian and nonesian have characteristic tetrapod assemblages in the karoo basin of south africa the lystrosaurus assemblage zone and the lower two thirds of the cynognathus assemblage zone respectively the middle triassic lvfs perovkan and berdyankian have characteristic assemblages from the russian ural foreland basin the tetrapod assemblages of the donguz and the bukobay svitas respectively the late triassic lvfs otischalkian adamanian revueltian and apachean have characteristic assemblages in the chinle basin of the western usa the tetrapod assemblages of the colorado city formation of texas blue mesa member of the petrified forest formation in arizona and bull canyon and redonda formations in new mexico since the triassic lvfs were introduced several subdivisions have been proposed lootsbergian can be divided into three sub lvfs nonesian into two adamanian into two and revueltian into three however successful inter regional correlation of most of these sub lvfs remains to be demonstrated occasional records of nonmarine triassic tetrapods in marine strata palynostratigraphy conchostracan biostratigraphy magnetostratigraphy and radioisotopic ages provide some basis for correlation of the lvfs to the standard global chronostratigraphic scale these data indicate that lootsbergian uppermost changshingian induan and possibly earliest olenekian nonesian much of the olenekian perovkan most of the anisian berdyankian latest anisian and ladinian otischalkian early to late carnian adamanian most of the late carnian revueltian early middle norian and apachean late norian rhaetian the triassic timescale based on tetrapod biostratigraphy and biochronology remains a robust tool for the correlation of nonmarine triassic tetrapod assemblages independent of the marine timescale

high resolution temperature profiles measured with stratospheric balloons near the andes mountains a spectral analysis of two balloon soundings of temperature performed in the troposphere and lower stratosphere over the andes mountains in argentina with a vertical resolution of 10 m has been performed the first and second soundings launched at the same location were performed during unusually calm and disturbed atmospheric conditions respectively considerable deviations from the 3 value predicted for the spectral slopes in the power law range by current saturation theories are found these departures are reduced if the data resolution at disposal is diminished thereby eliminating the highest wavelength harmonics slopes do not clearly steepen with increasing height as suggested by other authors and topography seems to be responsible for this fact at low altitudes the spectral amplitude increase with height detected from recent lidar data is corroborated only in the sounding with calm atmospheric conditions spectra are found to scale with the buoyancy frequency not as simply as suggested by the saturation models

first record of stereospondyls tetrapoda temnospondyli in the upper triassic of southern brazil abstract stereospondyls survived the permo triassic extinctions in a refuge probably located in the landmass that nowadays comprises australia subsequently they radiated to other parts of pangaea reaching their highest distribution and diversification during the early triassic an incomplete interclavicle from the caturrita formation represents their first record in the upper triassic of brazil previously upper triassic south american stereospondyls were restricted to argentina this new record reinforces a former hypothesis that suggests the presence of a more diverse stereospondyl fauna in south america during the late triassic than previously assumed additionally the presence of a stereospondyl and a phytosaur in the caturrita formation reinforces the hypothesis of a change to more humid climatic conditions in the parana basin during the upper triassic the record of early triassic stereospondyls in south america suggests that they first colonized brazil and or uruguay spreading from south africa during the early triassic subsequently reaching argentina up till now there is no record of middle triassic stereospondyls in either argentina and brazil probably due to either taphonomic bias or insufficient prospecting despite the lack of direct evidence one should not dismiss an earlier stereospondyl colonization of argentina still during the early or middle triassic

vertebrate dinoturbation from the caturrita formation late triassic parana basin rio grande do sul state brazil abstract the caturrita formation is a lithostratigraphic unit that comprises the ladinian eonorian sequence of the parana basin it has been interpreted as deposits of alluvial plains and meandering rivers purported fossil tracks found in this formation at faxinal do soturno county rio grande do sul state brazil are concave circular shaped structures with a laminar deformation some show digitiform projections and at least three are aligned they are interpreted as a disruption of the substrate homogeneity caused by bioturbation of tetrapods in some of these there is a distinct color pattern more reddish than the surrounding substrate this is interpreted as a result of differential diagenesis the features remain enigmatic tracks but were probably made by prosauropod dinosaurs the dominant terrestrial herbivore group from the end of the triassic in gondwana strata

temnospondyls from the beaufort group karoo basin of south africa and their biostratigraphy abstract the permo triassic beaufort group karoo basin of south africa is biostratigraphically subdivided into eight temporally successive assemblage zones based on therapsids mammal like reptiles the temnospondyli fossil tetrapods usually regarded as extinct amphibians are second only to therapsids in terms of diversity and abundance in these strata with nine higher level taxa families known temnospondyls are also playing an increasingly important role in biostratigraphy and correlation of the beaufort strata the lower beaufort group late permian contains six of the eight biozones but only one temnospondyl family the rhinesuchidae whose record in the karoo is the richest in the world however rhinesuchid taxonomy remains in flux and the group is thus of limited biostratigraphic utility the early triassic lystrosaurus assemblage zone middle beaufort group contains the rhinesuchidae amphibamidae lydekkerinidae tupilakosauridae rhytidosteidae mastodonsauridae and trematosauridae although the biostratigraphy of temnospondyls within this biozone is poorly constrained the uppermost reaches of the lystrosaurus biozone contain a paucity of fossils but includes kestrosaurus mastodonsauridae and trematosuchus trematosauridae taxa previously thought to pertain to the lower part of the overlying cynognathus biozone the late early to middle triassic cynognathus assemblage zone upper beaufort group hosts the mastodonsauridae trematosauridae brachyopidae laidleriidae and possibly the rhytidosteidae based largely on the spatial and temporal distribution of mastodonsaurids this biozone has been biostratigraphically subdivided into a lower a middle b and upper c subzones characterised by differing ages and faunas

saturated gravity wave spectra measured with balloons in mendoza argentina spectral results from a sounding of temperature and wind velocity between 11 9 and 23 1 km performed with an open type stratospheric balloon near the andes mountains are reported the use of this kind of balloons and high performance instruments allowed to attain better spatial resolution around 2 5 meters during the descent than previous results and other sounding techniques this high resolution permitted to study the complete interval of altitude data in three consecutive subintervals below around and above the tropopause each of these subintervals shows different saturation characteristics some differences have been found with the general pattern of power spectral densities reported by different theories a large amplitude wave of around 1 8 km and possibly originated in the mountain relief is clearly observed in the temperature vertical and shear wind velocity components

zeolites in petroleum and natural gas reservoirs zeolites have been reported in petroleum and natural gas reservoirs of a wide range of geological ages from many parts of the world such zeolite bearing oil and gas reservoirs are not comparatively large in number and scale however where present in petroleum and natural gas reservoirs zeolites can have profound effects on the quality of the reservoirs affecting rock porosity and permeability zeolite containing reservoir rocks vary widely lithologically including not only porous pelitic sedimentary rocks but also volcanogenic rocks and even fractured intrusive and plutonic rocks several different genetic types of zeolite occurrences have been distinguished and classified e g hay 1966 1986 1995 iijima 1980 1986 as hay and sheppard discussed and summarized in an earlier chapter this volume in addition the organic origin theory for the formation of economic oil and gas resources seems to have been universally accepted including the prominent kerogen decomposition theory summarized by tissot and welte 1978 sedimentary basins filled by very thick sequences of sedimentary strata containing organic rich source rocks and porous reservoir rocks are considered necessary for producing hydrocarbon resources such sedimentary basins develop primarily through rifting or in relation to arc formation at active plate boundaries and they are often accompanied by heating and extensive volcanic activity most types of zeolite occurrence are consequently constrained to burial diagenesis uplift related late stage diagenesis surdam and boles 1979 boles 1993 and hydrothermal alteration as will be discussed in this chapter zeolites in hydrocarbon reservoir rocks occur commonly as cements and grain replacements in the form of disseminated microcrystalline aggregates and occasionally as macroscopic crystals in vugs and veins it was in 1950s that coombs and co workers pioneered the petrologic study of rock forming zeolites through their classic research on burial metamorphism of the triassic geosynclinal deposits in south syncline new

clay mineral assemblages and analcime formation in a palaeogene fluvial lacustrine sequence maiz gordo formation palaeogen from northwestern argentina abstract the palaeogene maiz gordo formation is one of the main lacustrine events recorded in northwestern argentina it consists of sandstone mudstone and limestone beds 200 m thick deposited in a brackish alkaline lake and braided alluvial systems the maiz gordo lake evolved mainly as a closed system with brief periods as an open one x ray diffraction xrd and scanning electron microscopy sem were used to study samples from seven sites corresponding respectively to proximal intermediate and transitional positions of the fluvial environment and marginal and inner lake environment focusing on the clay mineralogy and analcime formation the basinward zonation of diagenetic minerals identified in the maiz gordo lake was mordenite analcime k feldspar although not a typical zonation of saline alkaline lakes it does indicate an increase in salinity and alkalinity towards the centre in proximal fluvial settings smectite predominates at the base of the sequence with scarce kaolinite towards the top a striking increase in kaolinite content suggests a change from a relatively arid climate with alternating humid and dry seasons towards a warm and humid climate kaolinite content clearly decreases in a basinward direction such a variation is attributable to changes in hydro geochemistry denoting the progressive influence of the brackish and alkaline lake water on interstitial pores sem images of intermediate fluvial samples reveal authigenesis of illite at the expense of kaolinite booklets in littoral and inner lake settings the clay fraction is composed of muscovite sometimes with subordinate smectite analcime occurs in variable amounts in all sedimentary facies in rock pores or filling veins it forms subhedral square to hexagonal or anhedral rounded crystals denoting that they coarsened at low to moderate degrees of supersaturation although the mordenite identified in a fluvial level would have been the precursor of analcime in the maiz gordo basin no textural evidence of analcime formation through replacement of mordenite or other precursor zeolite was found hence it is more probable that analcime formation took place by direct authigenic precipitation or through the reaction between interstitial brines and clay minerals or plagioclase

thermogenetic degradation of early zeolite cement an important process for generating anomalously high porosity and permeability in deeply buried sandstone reservoirs abstract diagenetic explanations to anomalously high porosities and permeabilities in deeply buried sandstones have been presented for many reservoirs for example grain coatings of microquartz or chlorite can preserve porosity by preventing succeeding quartz overgrowths and dissolution of grains or cement can generate secondary porosity anomalously high porosity and permeability up to 25 and 500 md respectively characterize the deeply buried 5 km upper jurassic shoreface sandstones of the gert member heno formation in the hejre field in the danish central graben optical cathodoluminescence and scanning electron microscopy were used to characterize the petrography and diagenetic changes that resulted in this high pressure and high temperature hpht reservoir this was supplemented by chemical analyses icp oes and icp ms mineralogical composition xrd and oxygen isotope composition of quartz and calcite cement sims the petrographic investigation shows that none of the known explanations for anomalously high porosity and permeability can be applied hence a new hypothesis for deeply buried sandstones in contact with lavas and volcaniclastic lithologies is proposed the new hypothesis includes reducing mechanical compaction due to early patchy zeolite cement which was sourced from adjacent lavas and volcaniclastic rocks locally stylolites developed where zeolite cement was less effective hence the present overpressure formed at a later stage increased temperatures during burial resulted in thermal instability of the zeolite cement which was dissolved and authigenic k feldspar and quartz precipitated instead this resulted in a reduction of the cement volume of up to 70 if the zeolite was k heulandite and a corresponding relative porosity increase thus a reduction in cement volume was generated by replacing zeolite of an open crystal structure with mineral phases k feldspar and quartz of denser crystal structures the thermogenetic breakdown of zeolite was forced by increased temperatures during burial this process may explain previously enigmatic highly porous and permeable deeply buried sandstone reservoirs

limb sounders tracking topographic gravity wave activity from the stratosphere to the ionosphere around midlatitude andes several studies have shown that the surroundings of the highest andes mountains at mid latitudes in the southern hemisphere exhibit gravity waves gw generated by diverse sources which may traverse the troposphere and then penetrate the upper layers if conditions are favorable there is a specific latitude band where that mountain range is nearly perfectly aligned with the north south direction which favors the generation of wavefronts parallel to this orientation this fact may allow an optimization of procedures to identify topographic gw in some of the observations we analyze data per season to the east and west of these andes latitudes to find possible significant differences in gw activity between both sectors gw effects generated by topography and convection are expected essentially on the eastern side we use satellite data from two different limb sounding methods the global positioning system gps radio occultation ro technique and the sounding of the atmosphere using broadband emission radiometry saber instrument which are complementary with respect to the height intervals in order to study the effects of gw from the stratosphere to the ionosphere activity becomes quantified by the gw average potential energy in the stratosphere and mesosphere and by the electron density variance content in the ionosphere consistent larger gw activity on the eastern sector is observed from the stratosphere to the ionosphere night values however this fact remains statistically significant at the 90 significance level only during winter when gw generated by topography dominate the eastern sector on the contrary it is usually assumed that orographic gw have nearly zero horizontal phase speed and will therefore probably be filtered at some height in the neutral atmosphere however this scheme relies on the assumption that the wind is uniform and constant our results also suggest that it is advisable to separate night and day cases to study gw in the ionosphere as it is more difficult to find significant statistical differences during daytime this may happen because perturbations induced by gw during daytime are more likely to occur in a disturbed environment that may hinder the identification of the waves

diagenetic transformation of clinoptilolite to analcime in silicic tuffs of hokkaido japan diagenetic clinoptilolite and analcime are present in the diagenesis of tertiary marine silicic tuffs in the miti toyokoro borehole hokkaido japan chemical analysis sem and petrographic observations show the mechanism of clinoptilolite to analcime transformation na k clinoptilolite na k 6 4 an alteration product of volcanic glass is detected at depths of 1230 to 2710m a more na rich clinoptilolite na k 9 1 discovered at depths between 2590 and 2710 m is a result of a cation exchange mechanism the formation of analcime at greater depths is due to a microdissolution precipitation mechanism that is na rich clinoptilolite dissolved and analcime precipitated as a result of increasing burial at 2710 m analcime occurs next to the na rich clinoptilolite and it is assumed that the na rich clinoptilolite is an intermediate phase

11 years of rayleigh lidar observations of gravity wave activity above the southern tip of south america gravity wave gw activity is analyzed using temperature t data retrieved from a rayleigh lidar at rio gallegos argentina 51 6 s 69 3 w gw characteristics are derived from 302 nights of observations providing more than 1018 h of high resolution lidar data between 20 km and 56 km height from august 2005 to december 2015 t measurements are performed by a differential absorption lidar dial instrument this lidar was the southernmost outside antarctica until the end of 2017 rio gallegos is an exceptional place to observe large amplitude gw every lidar measurement is classified according to its relative position to the polar vortex the lidar measurements are compared with collocated sounding of the atmosphere using broadband emission radiometry saber and global positioning system radio occultation gps ro data the different instruments show different windows of the gw spectrum providing complementary observations in general the geometric mean of the specific gw potential energy pe is larger during winter and spring than during summer and autumn the largest geometric mean of pe is found inside the vortex and decreases monotonically at its edge outside it and when there is no vortex the same behavior is observed with satellite data on average it can be seen that lidar observations provide larger pe values than limb sounding measurements from a morlet continuous wavelet transform analysis 3 distinct modes are captured from saber and from gps ro data at the upper and lower stratosphere respectively in particular a systematic 3 5 4 years oscillation possibly related to el nino southern oscillation is observed