biogenicity of silica precipitation around geysers and hot spring vents north island new zealand abstract before anthropogenic modifications ohaaki pool broadlands ohaaki and dragon s mouth geyser wairakei emitted waters at temperatures of 93 98 c the siliceous sinter that precipitated around their vents has the characteristics of geyserite a dense laminated deposit of presumed abiogenic origin that was precipitated from waters too hot 73 c to support microbes other than thermophilic bacteria petrographic and sem examinations of the sinters that surround the vent of dragon s mouth geyser and form the pool rim dam of ohaaki pool show that they incorporate columnar stromatolites and silicified laminated stromatolitic mats that contain well preserved filamentous microbes at both localities the microbes lack evidence of desiccation or shrinkage which implies that they were silicified rapidly at or shortly after their death microbe preservation is commonly spectacular even the trichome is recognizable in many specimens although replacement by silica preserved the cells of the trichome cell walls and septae were not preserved possibly because they were destroyed by autolysis before silicification the sheath that surrounded the trichome is normally well preserved however late silica precipitation produced thick external encrustations of amorphous silica around many sheaths although boiling and very hot 90 c waters were discharged temperatures at many sites surrounding the vents remained sufficiently low and moist to support a microbial community that included thermophilic bacteria and cyanobacteria in these cooler niches the microbes and their biofilms served as highly favorable templates for the nucleation and growth of amorphous silica and collectively provided a microbial framework for the laminated accretionary sinter silica was supplied from supersaturated spring and geyser fluids that were delivered to sites of sinter precipitation as air cooled spray as proximal runoff or as the result of oscillations in the surface level of the spring or geyser pool waters in the field and in hand specimen the resulting columnar sinter appear to be identical in morphology to that inferred to originate from abiotic silica precipitation in a sterile environment consequently some columnar spicular and stratiform geyserites are probably not abiotic precipitates but are true silica stromatolites

mobility and fractionation of rare earth elements in argillaceous sediments implications for dating diagenesis and low grade metamorphism abstract we report sm nd and rb sr data for the fine fractions of lower paleozoic argillaceous rocks from wales uk and new york usa spanning the range of low grade metamorphic conditions from the diagenetic zone zeolite facies to the epizone greenschist facies in all cases leaching of the fine fractions results in a high 147 sm 144 nd 0 09 0 29 acid soluble component and a complementary low 147 sm 144 nd 0 05 0 14 residual component the observed fractionation is an ancient feature related to diagenesis burial and metamorphism the magnitude of sm nd fractionation between leachates and residues as well as the resulting sm nd ages vary as a function of grain size and metamorphic grade uncleaved welsh mudrocks of the diagenetic zone yield sm nd leachate residue ages of 453 484 ma in agreement with their llanviian to caradocian biostratigraphic ages whereas higher grade rocks of the anchizone and epizone yield sm nd ages as young as 413 ma these ages are transitional between the time of deposition and the time of regional deformation related to the acadian orogeny at 390 ma distinct convex upward rare earth element ree patterns of the leachates suggest that the precipitation of early diagenetic apatite controls the trace element budget of the rock forcing a depletion of middle rees on the subsequently formed diagenetic phyllosilicates the amount of organic matter present and the extent of later prograde reactions are probable modifiers of this fractionation process ordovician and devonian clastic rocks associated with the trenton and onondaga limestones of new york yield single sample and multi sample sm nd isochron ages that agree well with their biostratigraphic ages of 454 ma and 390 ma respectively the ree fractionation observed in shale leachates of the ordovician utica formation is related to ca mg of the bulk rock and hence to the composition of the diagenetic carbonate cement in all cases the sm nd system remained closed subsequent to the peak of diagenesis or metamorphism including the north american rocks that show no evidence of being isotopically reset during widespread remagnetization of the subjacent limestone units in the late paleozoic

propagation and the vertical structure of the madden julian oscillation abstract the madden julian oscillation mjo dominates tropical variability on time scales of 30 70 days during the boreal winter spring it is manifested as an eastward propagating disturbance with a strong convective signature over the eastern hemisphere the space time structure of the mjo is described using the national centers for environmental prediction national center for atmospheric research reanalysis advanced very high resolution radiometer outgoing longwave radiation observed sea surface temperature and the climate prediction center merged analysis of precipitation empirical orthogonal function analysis is used to identify the convective signature of the mjo and regression is used to identify key relationships with the convection compared to analyzing successive years of data the selection of years of strong mjo activity results in a more robust lead lag structure and an increase in explained variance the mjo exhibits a rich vertical structure with low level moisture convergence bein

mineralogy and geochemistry of ammonian illite in intra seam partings in permo carboniferous coal of the qinshui coalfield north china abstract ammonian illite is observed to be presented in the intra seam coal partings of the permo carboniferous coal seams from the qinshui coalfield north china this paper provides new insights into its geochemical and mineralogical characteristics as well as the factors influencing its formation and its nitrogen isotope ratios the interlayer cations of ammonian illite in the samples presented in this study were dominated by nh 4 with a certain amount of k and distributed homogeneously in each illite layer ammonian illite has an nh 4 nh 4 k ratio of 0 87 on average with a basal spacing d 001 10 267 a on average greater than those of potassian illite and muscovite but lower than that of tobelite the average stoichiometric formula of the ammonian illite was inferred as nh 40 67 k 0 11 al 1 90 fe 0 06 mg 0 04 al 0 68 si 3 32 o 10 oh 2 and the average si al iv ratio 4 88 was found to be higher than that of tobelite this indicates that the conversion of ammonian illite to tobelite includes the expulsion of si from the tetrahedral sheets and the incorporation of al into the octahedral and tetrahedral sheets the d 005 is influenced not only by the nh 4 nh 4 k ratio but also to some extent by the entrance of al iv into tetrahedral sites it is inferred that the ammonian illite was formed by the incorporation of si into pre existing kaolinite during diagenesis and that its formation was influenced not only by the diagenetic temperature but also by the depositional environment brackish water favors the formation of ammonian illite during deposition the nh 4 of the ammonian illite was mainly derived from pyrrolic n 5 and pyridinic n 6 nitrogen groups at the margins of the coal s carbon matrix during diagenesis on average it has a 15 n value of 8 0 much higher than that of total coal nitrogen 3 9 on average this is related mainly to the higher 15 n values of n 5 and n 6 than the quaternary nitrogen group n q within the carbon matrix

geochemistry and diagenesis of miocene lacustrine siliceous sedimentary and pyroclastic rocks mytilinii basin samos island greece abstract a late miocene non marine stratigraphic sequence composed of limestone opal ct bearing limestone porcelanite marlstone diatomaceous marlstone dolomite and tuffite crops out on eastern samos island this lacustrine sequence is subdivided into the hora beds and the underlying pythagorion formation the hora beds is overlain by the clastic mytilinii series which contains turolian late miocene mammalian fossils the lacustrine sequence contains volcanic glass and the silica polymorphs opal a opal ct and quartz volcanic glass predominantly occurs in tuffaceous rocks from the lower and upper parts of the lacustrine sequence opal a diatom frustules is confined to layers in the upper part of the hora beds beds rich in opal ct underlie those containing opal a the occurrence of opal ct is extensive encompassing the lower hora beds and the sedimentary rocks and tuffs of the pythagorion formation a transition zone between the opal a and opal ct zones is identified by x ray diffraction patterns that are intermediate between those of opal ct and opal a perhaps due to a mixture of the two polymorphs diagenesis was not advanced enough for opal ct to transform to quartz or for volcanic glass to transform to opal c based on geochemical and mineralogical data we suggest that the rate of diagenetic transformation of opal a to opal ct was mainly controlled by the chemistry of pore fluids pore fluids were characterized by high salinity moderately high alkalinity and high magnesium ion activity these pore fluid characteristics are indicated by the presence of evaporitic salts halite sylvite niter high boron content in biogenic silica and by dolomite in both the opal a and opal ct bearing beds the absence of authigenic k feldspar borosilicates and zeolites also support these pore fluid characteristics additional factors that influenced the rate of silica diagenesis were host rock lithology and the relatively high heat flow in the aegean region from miocene to holocene

intraseasonal teleconnection between north american and western north pacific monsoons with 20 day time scale abstract based on a recently released high resolution reanalysis dataset for the north american region the intraseasonal variability isv with a time scale of about 20 days of the north american monsoon nam is examined the rainfall signals associated with this phenomenon first emerge near the gulf of mexico and eastern pacific at about 20 n they subsequently migrate to the southwestern united states along the slope of the sierra madre occidental the rainfall quickly dissipates upon arrival at the desert region of arizona and new mexico aznm the enhanced rainfall over aznm is accompanied by strong southeasterly low level flow along the gulf of california this pattern bears strong resemblance to the circulation related to gulf surge events as documented by many studies the southeasterly flow is associated with an anomalous low vortex over the subtropical eastern pacific ocean off california and a midlatitude anticyclone over the central united states in the lower troposphere this flow pat

subsurface dissolution of heavy minerals frio formation sandstones of the ancestral rio grande province south texas abstract oligocene sandstones frio formation of south texas deposited by the ancestral rio grande contain a heavy mineral assemblage that is markedly altered even in the shallowest sample examined approximately 1 km depth the weight fraction of detrital heavy minerals in the modern rio grande is approximately 1 whereas subsurface frio sandstones contain as little as 0 1 or less heavy minerals modern rio grande sand contains a diverse and unstable heavy mineral assemblage dominated by pyroxenes amphiboles and an assortment of iron titanium oxides minor components include apatite garnet sphene epidote and zircon heavy minerals in subsurface oligocene sandstones include abundant apatite zircon and titanium oxide among detrital components minor iron rich garnet also survives in the subsurface to depths of about 3 km other very stable but also very minor heavy minerals include tourmaline chromite spinel and monazite locally the heavy mineral fraction in the frio is dominated by authigenic components such as siderite pyrite or barite authigenic sphalerite is also observed among the heavy minerals feldspars and rock fragments suggest that sediment deposited by the ancestral rio grande was more strongly dominated by volcanic detritus than is the modern river it is reasonable to infer that the initial heavy mineral assemblage of the frio formation was likewise more unstable than that which appears today in the rio grande thus heavy mineral loss determined by comparing subsurface frio sandstones with the sand in the modern rio grande is conservative comparison of sr and nd concentrations in modern rio grande sands and subsurface frio sandstones suggests that heavy mineral destruction in the subsurface does not cause major perturbations of whole rock isotopic systems involving these elements

the edison magnetite deposits in the context of pre syn and post orogenic metallogenesis in the grenville highlands of new jersey most of the magnetite deposits of the eastern grenville province have been described as precipitates from hydrothermal solutions derived from metamorphic processes from early late or post grenville granites or as metasediments granites host many of these deposits but others including the historic edison iron mines of new jersey are hosted by potassium feldspar gneiss commonly interpreted as meta arkose our new geochemical data indicate however that the protolith of the potassium feldspar gneiss is rhyolite not arkose supporting evidence includes i the absence of an underlying potassic provenance for arkosic sediment ii potassium and sodium contents among host rocks that exceed the range of arkose but are consistent with a type rhyolite and iii a close chemical resemblance of the potassium feldspar gneiss to an a type granite byram granite that is closely associated in time and space as the ore zone through the edison mines is approached the k na ratio of the host rocks undergoes

role of the boundary layer moisture asymmetry in causing the eastward propagation of the madden julian oscillation the moisture budget associated with the eastward propagating madden julian oscillation mjo was diagnosed using 1979 2001 40 yr ecmwf re analysis era 40 data a marked zonal asymmetry of the moisture relative to the mjo convection appears in the planetary boundary layer pbl below 700 hpa creatingapotentiallymoreunstablestratificationtotheeastofthemjoconvectionandfavoringtheeastward propagation of mjo the pbl integrated moisture budget diagnosis indicates that the vertical advection of moisture dominates the low level moistening ahead of the convection a further diagnosis indicates that the leading term in the vertical moisture advection is the advection of the background moisture by the mjo ascending flow associated with pbl convergence the cause of the zonally asymmetric pbl convergence is further examined it is found that heating induced free atmospheric wave dynamics account for 75 90 of the total pbl convergence while the warm sst anomaly induced by air sea interaction contributes 10 25 of the total pbl convergence the horizontal moisture advection also plays a role in contributing to the pbl moistening ahead of the mjo convection the leadingterm in the moistureadvectionis the advectionacross the backgroundmoisture gradient by the mjo flow in the western indian ocean maritime continent and western pacific the meridional moisture advection by the mjo northerly flow dominates while in the eastern indian ocean the zonal moisture advection is greater the contribution of the moisture advection by synoptic eddies is in generalsmall ithas a negativeeffect overthetropicalindianoceanand westernpacificandbecomespositive in the maritime continent region

coherent fluctuations of extratropical geopotential height and tropical convection in intraseasonal time scales abstract coherent fluctuations between extratropical circulation and tropical conviction in the intraseasonal time scale are studied possible relationships between 500 mb height field and outgoing longwave radiation olr are examined using correlation complex eof and composite techniques results show that in the 20 70 day bands data there is a systematic evolution of extratropical wavetrains from eurasia across the pacific to north america and the north atlantic in the time scale of 5 to 10 days over the tropics the dominant mode of intraseasonal variation in convection is an east west dipole like feature which propagates from the western indian ocean eastward to the dateline with a quasi period of 40 50 days the space time evolution of these extratropical wavetrains is found to he coherent with the tropical dipolar convection and with the strongest convection over indonesia central pacific in approximate quadrature with the peak phase of the eurasia and pacific north america wavetrains while the

ammonium enrichment associated with diagenetic alteration in tertiary pyroclastic rocks from greece the ammonium ion has been measured in fresh volcanic rocks in vitric tuffs and in tuffs which have undergone secondary alteration the ammonium content of fresh lavas of a wide range of composition is shown to be negligible in contrast high concentrations of ammonium are found in pyroclastic rocks that have undergone diagenetic alteration data are given for three types of diagenetic alteration namely 1 hydration 2 zeolitization and 3 alteration to secondary k feldspar different levels of ammonium enrichment are associated with each type hydrated vitric tuffs from kozani in northern greece and heraklion in crete contain from 158 to 390 ppm nh 4 zeolitized ash and lapilli tuffs from santorini and from lefkimi ne greece are much lower in their ammonium content ranging from 12 to 56 ppm tuffs containing secondary k feldspar in addition to zeolites from metaxades n e greece have ammonium contents from 51 to 512 ppm measurements of fixed and exchangeable ammonium were used to distinguish between the ammonium held by zeolites and that held by k feldspars in the clinoptilolite and mordenite bearing tuffs from santorini and lefkimi most of the ammonium is in cation exchangeable form and must be held by the zeolites by contrast in the feldspar bearing tuffs from the metaxades area almost all the ammonium is fixed and it is inferred to be held mainly by secondary k feldspar

hydrogeologic control on zeolitic diagenesis of the white river sequence smectite opal ct and clinoptilolite are common alteration products in the white river sequence a mid tertiary unit in the great plains and northern rocky mountains the white river sequence is largely made up of fine grained tuffaceous material that is rich in unaltered rhyolitic glass smectite is ubiquitous and it or a precursor phase was present during white river soil formation but also formed after burial smectite fe from 5 to 7 fe 2 o 3 and ti from 0 4 to 0 8 tio 2 concentrations in mud rocks suggest formation from dacitic to latitic glass rhyotitic glass however was the primary source for opal ct and clinoptilolite opal ct and clinoptilolite have a highly variable distribution over macroscopic to regional scales of observation stable isotopic compositions of smectite 18 o smow 11 8 to 13 3 opal ct 18 o smow 19 9 to 24 3 and late diagenetic calcite 18 o smow 10 3 2 0 suggest that burial diagenetic reactions took place at temperatures ranging from 27 to 55 c clinoptilolite apparently formed in areas with high contact times between paleoground water and vitroclastic material in white river rocks of wyoming clinoptilolite occurs only in localities that are interpreted as lying within paleo ground water discharge zones in the great plains clinoptilolite is rare in eastern colorado and southern nebraska but progressively increases in abundance to the north reflecting a northward decrease in permeability zeolitic alteration near douglas wyoming changed the hydrologic role of tuffs from aquifers to aquitards tuffs were originally aquifers because of their high permeability 30 md relative to interbedded mud rocks 10 4 to 1 md signigicant thicknesses 0 5 to 2 m presentday and lateral continuity tuff alteration however decreased permeability by 4 orders of magnitude relative to glass rich portions similar diagenetic effects on mud rock permeabilities are likely mass flux into altered tuffs at douglas is indicated by an increase in bulk rock density from 1 3 g cm 3 for glass rich tuff to 1 7 and 2 0 g cm 3 respectively for zeolitic and siliceous counterparts local silica redistribution accouts for the bulk of the density increases a systematic increase in ba content of clinoptilolite over a 150 m vertical section from 0 1 to 6 6 mol of the exchangeable cations suggests that it was derived from underlying units

diagenetic modification of sm nd model ages in tertiary sandstones and shales texas gulf coast sm nd model ages of sandstones and shales from the oligocene frio formation of south texas and the paleocene eocene wilcox group of south central texas increase with increasing depth of burial depleted mantle model ages tdm of frio shales increase from ca 800 ma at 1 km of burial to ca 1000 ma at 4km in frio sandstones tdm increases from ca 750 ma at 1 km to over 1200 ma at 4 km of burial in wilcox shales tdm increases from ca 1300 ma to ca 1500 ma over a burial depth of 1 5 to 4 5 km tdm of wilcox sandstones increases from ca 1450 ma at 2 5 km of burial to as much as ca 2000 ma at 4 0 km the sampling scheme employed minimizes but does not eliminate the possibility that these trends in tdm are due to detrital variability close correlation of these trends with diagenetic changes in the rock and evidence of rare earth element mobility preserved in the diagenetic products suggests that diagenesis has modified tdm diagenetic modification of tdm in frio sandstone and wilcox shale is due primarily to loss of radiogenic nd whereas increased 147sm 144nd produces elevated tdm in deeper wilcox sandstones the tdm of frio shales does not change appreciably with depth owing to the opposite effects on tdm of decreased 147sm 144nd and decreased nd 0 loss of radiogenic nd is due primarily to reactions involving unstable volcanic detritus which is more abundant in the frio than in the wilcox decreased 147sm 144nd in authigenic illite and consequent increased 147sm 144nd in pore fluids results in elevated tdm in wilcox and frio sandstones containing late diagenetic cement and in decreased 147sm 144nd in deeper frio shale the similar tdm trends observed in both units which have different detrital characteristics suggest that modification of sm nd model ages in siliciclastic rocks may be commonplace during burial diagenesis

burial diagenesis of argillaceous sediment south texas gulf of mexico sedimentary basin a reexamination cuttings from a well through a thick section of miocene oligocene mudrocks from kenedy county texas spanning a depth range of 2130 to 5490 m 7000 to 18 000 ft have been studied petrographically and geochemically on the basis of whole rock chemical analyses the deepest samples have lost 18 wt and approximately vol mostly as caco3 mineral bound h2o and sio2 but including additional ca as well as sr light rare earth elements ree la ce nd sm fe and li k2o and rb have been added to the deeper rocks the large chemical changes are accompanied mineralogically by loss of detrital calcite kaolinite k feldspar ca plagioclase and muscovite gain of chlorite and albite and continued reaction of smectitic illite smectite i s to more illitic and k rich compositions throughout the entire depth interval of the well the large chemical changes in this thick mud rich interval almost certainly require advection of water free convection to accomplish the mass transfer initial variation in sediment composition is ruled out as a cause of the observed compositional changes with increasing depth because 1 a variety of immobile elements al2o3 tio2 zr hf heavy ree er yb th and sc remain constant relative to each other despite their uneven distribution across various particle size fractions in the sediments 2 deep frio shales are unlike quaternary gulf of mexico sediments or average shales and 3 unreasonable primary mineralogic compositions would be necessary to explain the chemical composition of the deep samples these results indicate that burial diagenesis of argillaceous sediment can be a considerably more open chemical process than is conventionally assumed that it can account for the two major chemical cements calcite and quartz in associated sandstones and that it mirrors secular changes in shales throughout geologic time

synoptic analysis of the pacific north american teleconnection pattern in this study we use various diagnostic techniques to investigate the synoptic evolution of the pacific north american teleconnection pattern pna national center for environment prediction national center for atmospheric research reanalysis data are used these data cover the years 1948 2008 for the months of november march it is found that the positive pna is initiated by enhanced convection over the western tropical pacific and weakened convection over the tropical indian ocean the excitation of the negative pna exhibits opposite features for both phases the response to tropical convection excites a small amplitude pna about 8 12 days prior to the pattern attaining its maximum amplitude this is followed by slow steady growth for about 5 days after which driving by synoptic scale waves via their eddy vorticity flux together with stationary eddy advection lead to much more rapid growth and the establishment of the full pna for the positive pna the synoptic scale waves propagate eastward into the midlatitude northeastern pacific where they are observed to undergo cyclonic wave breaking for the negative pna the synoptic scale waves first amplify over the midlatitude northeastern pacific and then propagate equatorward into the subtropics where they undergo anticyclonic wave breaking once established for both phases the pna appears to be maintained through a positive feedback that involves a succession of wave breakings these results suggest that preconditioning may play an important role in the formation of the pna for the positive pna in its early development the strengthening and eastward extension of the subtropical jet result in an increase in the cyclonic shear and a decrease in the meridional potential vorticity gradient features that are known to favour cyclonic wave breaking for the negative pna opposite changes were observed for the background flow which favour equatorward wave propagation and anticyclonic wave breaking the role of optimal growth is also discussed our results also suggest that the pna is potentially predictable 1 2 weeks in advance copyright 2011 royal meteorological society

authigenic silicates and silica polymorphs in the miocene saline alkaline deposits of the karlovassi basin samos greece the lower neogene unit of the karlovassi basin samos island greece was deposited in a continental basin during miocene times and consists of four successions overlying a basal conglomerate the four successions are from the base upward carbonates tuffaceous rocks claystones and porcelanites volcanic glass was originally abundant in the tuffaceous succession but is now represented by its diagenetic products including boron bearing k feldspar the zeolites clinoptilolite analcite and mordenite smectite opal disordered tridymite cristobalite cristobalite and minor amounts of the zeolites erionite phillipsite and chabasite and tridymite evaporite minerals such as gypsum celestite and thenardite are present along with authigenic silicates in tuffaceous intervals into the claystone succession authigenic silica polymorphs represented by opal and chalcedony were identified in the uppermost succession of porcelaneous limestones to chert five irregular concentric zones related to the presence and kind of zeolites and k feldspar are recognized in the lower neogene unit 1 a marginal zone of carbonate and detrital silicate minerals nonauthigenic silicates 2 a clinoptilolite zone 3 a mixed clinoptilolite analcite zone 4 an analcite zone and 5 a central boron bearing k feldspar zone the general pattern of zonation and distribution of authigenic silicates as well as their chemical characteristics indicates the presence of a saline alkaline lake during miocene times this lake is analogous to those of the same age which existed in southern yugoslavia and western turkey where borate sulfate and double carbonate deposits were formed along with authigenic silicates it is possible that a large continental area in the eastern mediterranean underwent large scale dessication which took place during the miocene messinian salinity crisis resulting in the development of highly saline alkaline lacustrine environments

variations in coal maceral chemistry with rank advance in the german creek and moranbah coal measures of the bowen basin australia using electron microprobe techniques abstract variations in the elemental composition of individual macerals in seams from the permian german creek and moranbah coal measures in the bowen basin of queensland have been studied over a wide range of coal ranks using light element electron microprobe techniques to establish the coalification tracks of key macerals in a single coal bearing interval from subbituminous through bituminous coal to anthracite vitrinite reflectance rv max in the seams studied increases from 0 39 in the western part of the basin to over 3 5 in the east apparently due to increases in burial depth the study extends significantly the rank range covered by previous work on elemental analysis of individual macerals in the gunnedah basin and provides a more useful basis than whole coal analysis to evaluate the performance of coals in different utilisation processes the microprobe results show that the carbon content of the telocollinite increases dramatically from 66 to 90 as the vitrinite reflectance of the coals rv max increases from 0 39 to around 1 75 but increases only slightly from 90 to 91 as rv max increases from 1 75 to 3 52 oxygen decreases from around 26 to approximately 5 as rv max increases from 0 39 to around 1 75 and then decreases only very slightly into the anthracite range the nitrogen content of the telocollinite in these coals also appears to decrease slightly with rank advance and appears moreover to display a relatively abrupt drop at around 2 rv max this may be associated with the development of ammonium illite in the mineral matter organic sulphur in the telocollinite on the other hand seems to remain essentially constant with rank advance at least in this particular succession in contrast to vitrinite fusinite and inertodetrinite have significantly higher but somewhat more constant carbon contents varying only from around 81 to 93 c over the rank range studied oxygen in these macerals decreases from around 12 to a little over 2 with the same degree of rank advance sulphur and possibly nitrogen also appear to be significantly lower in fusinite and inertodetrinite than in the vitrinite of the same coal samples semifusinite is somewhat more variable in composition with characteristics intermediate between those of the fusinite inertodetrinite and those of the vitrinite in the same coal over the rank range studied

palaeoenvironmental implications of aluminium phosphate sulphate minerals in early middle triassic continental sediments se iberian range spain abstract the presence of sr rich aluminium phosphate sulphate aps minerals in continental sedimentary rocks from the canizar and eslida formations along the eastern part of the iberian range spain is considered as evidence of acidic and oxidising conditions during early middle triassic times the formation of aps minerals occurred shortly after sedimentation in early diagenetic stages prior to the compaction of the sediments and most probably was related to the circulation of acidic meteoric waters such conditions might result from a sustained damaged environment or from multiple environmental crises but would have delayed the recovery of life after the end palaeozoic mass extinction aps minerals occur as small disseminated and idiomorphic pseudo cubic crystals 0 5 to 6 m long or as massive and polycrystalline aggregates replacing fragments of fine grained metamorphic rocks mainly metapelites textural data indicate that the formation of the aps minerals predated the quartz and illite cements and that they resulted from the destabilisation of pre existing minerals as evidenced by the replacement of slate fragments by aps minerals and hematite and by the close association of the disseminated aps crystals and kaolinite with altered detrital mica plates electron microprobe analyses and x ray diffraction study of the aps minerals indicate a rather homogeneous composition in different parts of the basin corresponding to solid solutions among woodhouseite svanbergite crandallite and goyazite the sources of strontium in the aps minerals remain unclear phosphorous was primarily supplied by dissolution of detrital phosphates under acidic conditions and sulphur derives from the weathering of pyrite

petrology and geochemistry of diagenetically altered tuffaceous rocks from the middle triassic of central spain abstract petrographical and geochemical analysis of altered tuffaceous rocks of the middle triassic from the iberian range in central spain shows that pedogenic processes and subsequent diagenesis have strongly modified the original mineralogy and textures these rocks are related to a magmatic episode that occurred at the buntsandstein muschelkalk unconformity in this region during the evolution of the iberian trough the tuffaceous rocks accumulated in saline ponds in an open and terminal flood plain setting their alteration is typified by neoformation of k feldspar and illite precipitation of chert and carbonate cements and replacements were also important processes resulting in intercalated chert beds and nodules much of the silica appears to be derived from extensive devitrification and weathering of glassy volcanic ash x ray diffraction analysis microscopic observations and edx microanalysis reveal that the chert consists of various types of chalcedony tridymite micro and megaquartz illite k feldspar and small amounts of albite in some of the nodules dolomite ankerite is also common enclosing anhydrite and barite relicts which are partially silicified different levels of ammonium enrichment have been found in each petrofacies type tuffs and tuffaceous rocks contain from 27 to 326 ppm mean 139 of nh4 underlying arkosic sandstones with authigenic k feldspar contain nh4 ranging from 48 ppm to 191 ppm mean 124 the nh4 was probably derived from decay of organic matter in the evaporitic environment of deposition and its incorporation into feldspar and illite as they formed from unstable volcanic glass sanidine plagioclase and vitric volcanic fragments this transformation could have occurred via the intermediate phases of smectite and zeolites the tuffaceous rocks also have a high content of b ranging from 61 ppm to 170 ppm mean 101 however high levels of b are not positively correlated with high levels of nh4 in the samples both b and nh4 can be contained in either k feldspar or illite but it is not possible to know how much is present in each mineral without separating the minerals comparison of spidergrams of the tuffaceous rocks with those in the underlying arkosic sandstones indicates similar patterns with positive anomalies in la sm and y and negative in nb p ti and yb although the tuffaceous rocks are slightly richer in total ree these data suggest that the distribution of ree must also be controlled by weathering and diagenetic reactions and cannot be used for discrimination between volcanic and nonvolcanic sandstones

detection of shallow hydrocarbons with high frequency seismic reflection data abstract high frequency 200 to 15 000 hz high resolution seismic reflection profiles can be a valuable tool in the exploration for offshore hydrocarbon accumulations the occurrence of hydrocarbons particularly natural gas either in the water column or shallow subbottom can result in strong acoustic impedance density velocity contrasts which may produce a number of anomalous seismic responses including 1 water column anomalies which are strong reflections that rise from the ocean bottom into the overlying water column as a result of natural gas seepage 2 subbottom amplitude anomalies bright spots that when found along geologic structures may indicate shallow hydrocarbon accumulations 3 seismic smears which are turbid chaotic high amplitude events that may indicate shallow gas charged sediments and 4 seismic wipeouts transparent zones commonly found below seismic smears or water column anomalies indicating total reflection and or absorption of seismic energy in an overlying zone of gas a high frequency high resolution seismic reflection profile survey of the continental margin off northern santa cruz county california using both a 300 joule uniboom and a 1 kilojoule sparker has resulted in the detection of all four of these seismic anomalies the shelf here is cut diagonally by the san gregorio fault zone which marks the southeast boundary of the outer santa cruz basin northeast of the san gregorio fault the shelf is dissected by the monterey bay fault zone more than 100 water column anomalies gas seeps have been detected some of which rise over 50 m 160 ft into the overlying water column most water column anomalies correlate with subbottom geologic structures such as anticlines faults and truncated tilted strata several subbottom amplitude anomali s seismic smears and seismic wipeouts have also been detected and correlated with structures all these anomalies have been found in association with the middle miocene monterey formation the late miocene santa cruz mudstone and the pliocene purisima formation samples of natural gas have also been collected from a shallow end page 521 coastal water well geochemical analyses indicate the presence of 74 to 91 methane 7 to 23 nitrogen 2 carbon to dioxide and 1 ethane the gas appears to be thermogenic in origin as it has dgr13c values of 29 51 to 32 5 pmil pdb oil saturated sandstones have also been dredged from a depth of 700 m 2 300 ft in ascension submarine canyon further indicating the natural seepage of hydrocarbons in this area we interpret these natural hydrocarbon seeps to be the result of migration from depth along active faults within the san gregorio and monterey bay fault zones high frequency high resolution seismic reflection surveys in unexplored offshore areas may yield evidence for hydrocarbons that are not detectable with conventional deep penetrating low frequency 100 hz seismic reflection systems and thus may be very valuable in the search for oil and gas accumulations end of article last page 522

the origin and dispersion characteristics of the observed tropical summertime synoptic scale waves over the western pacific abstract the origin initiation and dispersion behavior of the observed summertime synoptic scale disturbances in the tropical western pacific are studied these westward propagating disturbances have the strongest growth rate over the region of 130 160 e off the equator the three dimensional wave activity flux associated with a wave packet in the vicinity of this region is computed in general wave activity is directed westward there is accumulation of activity flux which gives rise to the amplification of waves in the low levels such accumulation can be attributed to the convergence of both the mean flow and the intrinsic group velocity diabatic forcing also contributes to the growth of disturbances and is most important in the 500 600 hpa layer along the east west oriented storm tracks of the synoptic scale disturbances there are two different dynamical regimes west of 150 e enhanced convection is associated with increased specific humidity at the top of the planetary boundary layer an

intraseasonal variation of the summer rainfall over the southeastern united states this study characterizes the intraseasonal variability isv in the southeastern united states se us rainfall in boreal summer and delineates the associated dynamical processes featuring three way interactions among the se us rainfall the central us low level jet llj and the north atlantic subtropical high nash the analysis reveals that the isv of the se summer rainfall peaks at the 10 20 day timescales the physical mechanisms for the three way interactions on the 10 20 day timescales are proposed when the nash attains a minimum strength the reduced size of the nash is accompanied with an eastward retreat of the western ridge of the nash leading to a decrease in the zonal pressure gradient and consequently a weakening of the llj 1 day after the weakened llj and the eastward shifted nash western ridge induces anomalous cyclonic circulation over the se us moves preferred regions of moisture convergence from central us to the se us and 3 days later the se us rainfall attains its maximum strength the excessive latent heating associated with the enhanced se us rainfall excites an anomalous anticyclone northeast of the rainfall region resulting in an increase in the nash intensity that peaks 2 days after the maximum se us rainfall the nash subsequently expands with its western ridge moving westward zonal pressure gradient restored and llj strength recovered an anomalous anticyclone then emerges over the se us and suppresses rainfall marking the shift from an intraseasonal wet phase to dry phase in this region a more rigorous proof of these causalities demand carefully designed numerical experiments and further statistical analysis in future our results suggest that improved prediction of se us summer rainfall across intraseasonal scales depends critically on the model representation of the three way coupling among the nash the central us llj and the se us rainfall

origin of the intraseasonal variability over the north pacific in boreal summer abstractthe spatial structure and temporal evolution of the intraseasonal oscillation iso in boreal summer over the midlatitude north pacific ocean are investigated through the diagnosis of ncep reanalysis data it is found that the midlatitude iso has an equivalent barotropic structure with maximum amplitude at 250 hpa initiated near 120 w the iso perturbation propagates westward at a phase speed of about 2 4 m s 1 and reaches a maximum amplitude at 150 w a diagnosis of barotropic energy conversion shows that the iso gains energy from the summer mean flow in the iso activity region a center followed column averaged vorticity budget analysis shows that the nonlinear eddy meridional vorticity transport plays a major role in the growth of the iso perturbation there is a two way interaction between iso flows and synoptic eddies while a cyclonic anticyclonic iso flow causes synoptic scale eddies to tilt toward the northwest southeast northeast southwest direction the tilted synoptic eddies then

diagenetic processes influencing porosity in sandstones from the triassic buntsandstein of the iberian range spain abstract sandstones of the triassic buntsandstein of spain were studied in an attempt to quantify effects of diagenetic processes such as compaction cementation and leaching on reservoir properties samples were taken from shell well siguenza 44 3 some 110 km northeast of madrid drilled on the siguenza high in the iberian range the sandstones are arkoses to sublitharenites of a typical triassic redbed facies characteristic of the whole region the present day depth of the base buntsandstein is 538 m whilst a maximum burial depth of ca 2600 m was estimated from vitrinite reflectance 0 94 to 1 14 kaolinite temperature 76 c and illite crystallinity kuebler index 4 9 from an estimated average initial porosity of 38 porosity was reduced to the present value of 13 the strongest process to reduce porosity was found to be mechanical compaction causing a loss of 15 followed by chemical compaction pressure solution with a loss of about 6 the cement 11 4 r v apparently reduced the initial porosity by about only 5 early carbonate and sulphate cements are interpreted to have stabili sed the rock framework working against mechanical compaction and pressure solution this is supported by an increase in sutured grain contacts where early cements are absent or rare the later quartz cement interpreted to be largely the product from pressure solution has reduced porosity in a ratio of 0 5 1 this suggests that compaction continued after the formation of the late quartz cement although leaching was observed especially in feldspar grains clay and k feldspar neomorphosis is interpreted to have counteracted the formation of substantial secondary porosity permeability in the buntsandstein is generally low average 17 4 md and has been strongly affected by the alteration of feldspars to clay causing a wide range of permeability from 0 11 to 73 0 md

unusual sedimentary geodes filled by gold bearing hematite laths unusual mineralized and silicified carbonate rich geodes were found hosted in lower triassic red mudstones in central spain from their borders to their centres the geodes display a a millimetric carbonate crust b a quartz rim c massive dolomite d gold bearing iron rich infills hematite laths and goethite with up to 7000 ppm of gold and e calcite cements that sometimes seal the central hollow textural evidence indicates that the geodes were originally anhydrite which was subsequently replaced by quartz and dolomite the resultant porosity from this replacement or by later dissolution has been filled by epithermal gold bearing iron oxide hydroxides romanechite and calcite 13c values indicate the participation of meteoric waters in an environment which was characterized by both a sub desert climate and a temperate tropical climate oxygen signatures reflect very variable temperatures for all minerals with the exception of calcite which appears to have precipitated at 38 c iron oxide temperature values can reach up to 85 c epithermal stage the mineralogical assemblages of these unusual geodes denote early diagenetic replacement followed by the epithermal activity this mineralization is linked to the late hercynian calc alkaline volcanism of central spain the hiendelaencina mining district

redistribution of rare earth elements during diagenesis of turbidite hemipelagite mudrock sequences of llandovery age from central wales

application of the indophenol blue method to the determination of ammonium in silicate rocks and minerals abstract a colorimetric method is given for determining ammonium in silicate rocks and minerals at concentrations down to 1 ppm the sample is digested in cold hf and ammonia is then separated by distillation and measured colorimetrically as the indophenol blue complex using the reagents and procedures described here the problems of colour instability and poor reproducibility encountered by previous workers have been overcome

the fluvial architecture of the upper buntsandstein in the iberian basin central spain the cercadillo sandstone and siltstone css formation forms the upper part of the buntsandstein fluvial facies in the western margin of the iberian basin sedimentation was controlled by two major pre triassic tectonic systems the iberian ranges system nw se and the central system ne sw fluvial sedimentation during this period took place in coexisting braided and meandering channels together with associated ephemeral episodes this unusual association was due to a combination of structural control by the main normal faults coupled with large discharge fluctuations the css formation consists of two major fluvial sequences with very similar vertical patterns comprising low sinuosity stream deposits that pass upwards into high sinuosity deposits associated with extensive floodplain sediments a widespread calcrete horizon is developed at the top of the lower sequence and a surface with pedogenic features is present at the top of the upper sequence these horizons are interpreted to be the result of subaerial exposure during a period of no subsidence and equilibrium in the erosion sedimentation processes in the area probably due to quiescent periods on the master faults that delineate the basin minor changes within the sequences are probably due to discharge fluctuations of a climatic origin whereas the general vertical trend of the sequences is suggested to be tectonically controlled palaeocurrent data show a general flux of sediments to the south east parallel to the axis of the iberian basin but the final part of the upper sequence palaeocurrents to the north east are interpreted to indicate a local reactivation of secondary transverse faults in the south east part of the study area

causes of intraseasonal diabatic heating variability over and near the tibetan plateau in boreal summer the structure and evolution features of the first two leading modes of the intraseasonal diabatic heating variability over the tibetan plateau tp during northern summer are investigated using reanalysis and observational data both of the leading modes present a dominant 10 30 day intraseasonal oscillation iso the first mode is characterized by a perturbation center over the southern tp stp which remains quasi stationary and is closely related to the low latitude iso the associated low latitude iso is originated from the tropical western pacific wp and propagates westward northwestward toward northwestern india along the mean monsoon trough the westward propagation near the south china sea is mainly attributed to anomalous meridional vorticity advection and the advection of the planetary vorticity by iso flow the stationary feature of the perturbation over the stp is ascribed to the topographical features around the stp the intraseasonal heating variability over the stp is attributed to the alternation of anticyclonic and cyclonic flow associated with the westward propagating iso perturbation originated from the tropical wp the second leading mode is characterized by an east west asymmetric structure over the tp the intraseasonal diabatic heating anomaly propagates clockwise from the northwestern to eastern tp while a heating anomaly with an opposite sign propagates from the southeastern to western tp the mid latitude rossby wave trains play an essential role in forming the dipole structure the wave trains propagate southeastward before reaching the tp and then eastward as they cross the tp the source of anomalous water vapor over the tp is originated from lower latitudes the upper and lower level wave trains are well coupled over the tp exhibiting a baroclinic structure

an observational study of tropical midlatitude interaction on intraseasonal time scales during winter abstract eight northern hemisphere winters of five and ten day average midlatitude 500 mb heights and tropical outgoing ir are used in a correlative study of tropical midlatitude interaction the seasonal cycle and interannual variability are removed so that only intraseasonal variability remains results indicate that energy predominantly propagates from midlatitudes to the tropics for both five and ten day averaged data although the propagation is more apparent in five day averaged data this is evidenced by the fact that the largest tropical ir patterns are southeastward of the 500 mb point with which the ir field is correlated the result is interpreted in terms of a quasi stationary rossby wave which has an eastward component of group velocity the southwest northeast tilt of the 500 mb height correlation patterns indicating poleward momentum transport or equatorward wave propagation also supports the hypothesis that midlatitude flow drives the tropics lead and lag correlations show that when 5

interactions between the tropical iso and midlatitude low frequency flow in this study we investigate the interaction between the tropical intraseasonal oscillation iso and midlatitude atmospheric low frequency variability using observational data and numerical models with a special emphasis on the role of the synoptic eddy feedback a statistical closure for the synoptic eddy to low frequency flow feedback is constructed based on a singular value decomposition svd method with observational data applying this statistical closure to a barotropic model and a baroclinic 2 layer model we study the role of the synoptic eddy feedback in the midlatitude response to the tropical iso forcing both observational and modeling studies show that the strongest synoptic eddy forcing appears at the pacific and atlantic storm track regions and the synoptic eddy exerts a positive feedback to the midlatitude low frequency flow induced by tropical iso forcing our numerical experiments demonstrate the possible role of midlatitude disturbance forcing in the iso initiation at the equator the signal of the midlatitude perturbations propagates southeastward in the form of a rossby wave package it may reach the equator within several days under either easterly or westerly basic flow regimes the response at the equator has observed iso like structure and eastward propagation characteristics

elemental mobility in sandstones during burial whole rock chemical and isotopic data frio formation south texas abstract the deepest 3 5 km and most altered oligocene frio sandstones from south texas typically contain authigenic minerals that exceed 30 volume percent of the rock elemental and isotopic analyses of whole rocks confirm conclusions based on petrography that authigenesis is accompanied by substantial material transfer involving both import to and export from the sandstone from petrographic observations zr is apparently less mobile than other immobile elements such as al ti and ree but nonuniform initial distribution of zr due to sorting limits its usefulness for normalizing elemental variations if zr is assumed to be strictly immobile and zr was once uniformly distributed then volume loss of approximately 38 from the silicate fraction of the deepest sandstones is suggested over the range of burial depths for samples used in this study 0 9 4 3 km elemental trends controlled by feldspar reactions are the most readily documented dissolution and replacement of detrital k feldspar is accompanied by loss of 2 3 weight percent of k2o from the whole rock loss of more than half of the initial rb sr and pb also correlate with alteration of detrital feldspars 87sr 86sr ratios for whole rock and silicate fractions increase with depth as loss of nonradiogenic strontium characteristic of the volcanic rich detrital fraction is overwhelmed by more radiogenic strontium derived from deeper in the basin relatively constant na is compatible with feldspar alteration in which dissolution exceeds albitization changes in nd concentrat ons and nd also closely track the progress of alteration of detrital feldspar magnesium gain accompanies precipitation of authigenic chlorite and very minor ferroan dolomite whole rock calcium values are dominated by calcite that includes both detrital and authigenic components significant dissolution of detrital carbonate grains does not occur and calcium in authigenic carbonate cement exceeds by about 5 times the calcium released by dissolution of detrital silicates thus requiring considerable import of calcium and co2 material transfer on the scale observed demonstrates that burial diagenesis is an open system process for several major elements and introduces a major obstacle to use of elemental data for provenance interpretation defining the sources of materials transported into sandstones and the fate of materials exported is key to documenting the scale of system closure in sedimentary basins and requires a better understanding of diagenetic processes in mudrocks

diagenetic k feldspar pseudomorphs in the triassic buntsandstein sandstones of the iberian range spain early diagenetic k feldspar in the triassic buntsandstein of the iberian range spain occurs as pseudomorphs after detrital k feldspar or 99 untwinned commonly heavily clouded by vacuoles and tiny inclusions dark luminescing and are composed of numerous fine euhedral crystals of k feldspar the latter property suggests that the pseudomorphs form via dissolution of detrital k feldspar and plagioclase and precipitation of authigenic k feldspar x ray diffraction analysis shows that the authigenic k feldspar is intermediate microcline

geochemistry of mississippian tuffs from the ouachita mountains and implications for the tectonics of the ouachita orogen oklahoma and arkansas the ouachita orogeny was the result of plate convergence at the southern margin of the north american continent although the nature of the converging southern plate and the direction of subduction remain uncertain the presence of areally extensive tuff layers interbedded with shale in the mississippian stanley group of the ouachita mountains oklahoma and arkansas provides the potential to define the tectonic environment of volcanism from the geochemistry of the tuffs and thereby delimit the subduction configuration the tuffs contain relic primary magmatic quartz plagioclase and alkali feldspar and range from crystal to vitric rich mineralogical sorting and diagenetic effects have caused chemical variability within individual tuff units but overall the tuffs have retained their primary igneous geochemical characteristics the beavers bend and hatton tuffs are geochemically very similar and are more evolved higher sio2 rb th ree lower sr ba than the mud creek tuff the stratigraphically equivalent sabine rhyolite is geochemically distinct from the tuffs having less fractionated rare earth element ree patterns and different trace element ratios both the ouachita tuffs and sabine rhyolite have the geochemical characteristics of subduction related magmas for example strong depletion of nb and ta relative to other incompatible trace elements consideration of trace element systematics in the tuffs compared to those of modern high silica volcanic rocks from different subduction related tectonic settings suggests a continental arc origin and implies southward subduction beneath a southern continent during carboniferous ocean basin closure

from platform top to adjacent deep sea new source to sink insights into carbonate sediment production and transfer in the sw indian ocean glorieuses archipelago abstract over the past ten years a huge amount of source to sink studies have aimed to unravel the tectonic climatic and other processes that shape the landscape from mountains to the deep ocean interestingly these studies have been mainly dedicated to siliciclastic or mixed systems for which the connection between drainage basins continental shelves slope and basin environments are often well constrained here we present a study focusing on a source to sink study dedicated to a pure carbonate system located in the sw indian ocean glorieuses archipelago extensive field sampling and geophysical acquisition across the carbonate platform have allowed us to estimate the composition the lateral variability and volumes of neritic sands deposited on the platform top additional seismic and bathymetric surveys across the platform interior illustrate the presence of plurimetric sandy bodies deposited along the leeward platform edge corresponding to the export of carbonate sediments from the platform top toward the platform edge under the influence of dominant currents and wind driven processes high resolution seismic bathymetric data and sediment cores acquired along the leeward slope and basin adjacent to the carbonate platform highlight the presence of channel levee complexes and turbiditic lobes which have accumulated on the seafloor on top of a 250 m thick sedimentary basin at 2000 3400 m water depth our study points out that carbonate sands and aragonitic mud produced on the platform top during the holocene have been shed to the adjacent basin we also demonstrate that this routing system was active at least throughout the last three glacial interglacial cycles this study has important consequences for our understanding of carbonate sedimentation processes occurring in the vicinity of isolated carbonate platforms 1 it highlights the role of oceanographic conditions in the distribution of sediment on a platform top and its export along the platform edge and the adjacent basin 2 it contributes to quantify the productivity of a carbonate platform as well as its sediment storage capacity 3 a first estimate of a carbonate source to sink system is proposed demonstrating that 0 57 km3 of sediments have been produced during the holocene 0 3 km3 being presently stored on the platform and the remaining having been exported to the deep basin

provenance determined by ree th and sc analyses of metasedimentary rocks boyden cave roof pendant central sierra nevada california abstract ree th and sc analyses of metasedimentary rocks collected from the western sequence of the boyden cave roof pendant when compared with similar analyses of uppermost precambrian to cambrian miogeoclinal mudstones from the nopah range support the idea that rocks from the former area are a part of a large tectonically displaced fragment of the cordilleran miogeocline as proposed by r a schweickert and m m lahren for example ree distribution diagrams for samples from the western sequence of the boyden cave pendant show parallel light ree enrichment trends and negative eu anomalies that range from 0 61 to 0 86 and average 0 69 likewise ree distribution patterns for samples from the uppermost precambrian to cambrian cordilleran miogeoclinal section in the nopah range also show p rallel light ree enrichment trends and eu anomalies that range from 0 65 to 0 75 and average 0 68 on a la th se diagram samples from the boyden cave pendant cluster with specimens from the nopah range finally sediments from both areas have broadly similar th sc and th u ratios these results suggest that samples from the western sequence of the boyden cave pendant are composed of detritus like that shed from differentiated western north american upper continental crust during the early development of the cordilleran miogeocline such an interpretation is consistent with 1 the quartz rich to slightly feldspathic character of sandstones in the boyden cave pendant which implies a continental to transitional continental block provenance 2 a precambrian u pb age for detrital zirco extracted from a single sandstone bed and 3 the complete absence of volcanic material in the western sequence of the boyden cave pendant our results support the regional correlations and tectonic model proposed by r a schweickert and m m lahren and further suggest that although underutilized ree th and sc analyses are useful in evaluating stratigraphic sedimentologic and tectonic problems in complexly metamorphosed and deformed metaclastic terranes

structures and mechanisms of the northward propagating boreal summer intraseasonal oscillation abstract the spatial and temporal structures of the northward propagating boreal summer intraseasonal oscillation bsiso are revealed based on the analysis of both the echam4 model simulation and the ncep ncar reanalysis the bsiso structure and evolution characteristics simulated by the model bear many similarities to those derived from the ncep ncar reanalysis the most notable features are the remarkable meridional asymmetries relative to the bsiso convection in the vorticity and specific humidity fields a positive vorticity perturbation with an equivalent barotropic structure appears a few latitude degrees north of the convection center the maximum specific humidity also shows a clear northward shift in the lower troposphere two internal atmospheric dynamics mechanisms are proposed to understand the cause of the northward propagation of the bsiso the first is the vertical shear mechanism the key process associated with this mechanism is the generation of barotropic vorticity due to the couplin

the modulation of the subtropical and extratropical atmosphere in the pacific basin in response to the madden julian oscillation abstract the 40 yr ecmwf re analysis era 40 data are combined with a number of novel climatologies to conduct a comprehensive examination of the response of the subtropical and extratropical atmosphere over the pacific basin to an evolving madden julian oscillation mjo event the adopted approach constitutes a symbiosis of a climatological analysis during the northern hemisphere winter from 1979 to 2002 and a case study analysis of a distinct mjo event that occurred in january february 1993 the former is designed to obtain the general characteristics observed during a composite mjo life cycle while the latter is used to provide insight into the instantaneous mechanisms responsible for the observed composite evolution a primary component of the study involves the diagnosis of anomalous wave breaking activity in response to mjo forcing in the form of tropical convection and or upper level divergence wave breaking events are separated by their characteristic life cycles lc1 anticyclonic and lc2 c

fluctuations in northern hemisphere 700 mb height field associated with the southern oscillation abstract variations in the mid troposphere circulation associated with the southern oscillation so are investigated and documented using mean monthly 700 mb height data for the period 1951 79 the so was defined by a southern oscillation index soi consisting of the difference in normalized mean monthly sea level pressures at tahiti and darwin results for all four seasons are presented in the form of lagged as well as contemporaneous correlations and composites of height anomalies obtained separately for high and low soi values different so teleconnection patterns are observed for each season strongest so signals appear in the winter with soi leading the height field by one to two seasons the time lead may he useful in prognostic applications the correlation in the summer is negligible the winter teleconnection pattern over the north pacific north america north atlantic sector is similar to that shown by bjerknes and others patterns for other seasons are also presented the statistical signifi

early permian deep water allochthonous limestone facies and reservoir west texas conventional cores from six wells in southwest reagan and northern crockett counties texas recovered interbedded limestone conglomerate intraclast and bioclast limestone calcarenite and shale twenty one lithologies are grouped into six lithofacies based on study of slabbed core surfaces lithoclast rudstone floatstone porous bioclast lithoclast rudstone floatstone bioclast wackestone intraclast floatstone rudstone thin bedded grainstone packstone calcarenite and dark gray shale the limestone facies are interpreted on the basis of petrologic characteristics biota regional stratigraphic setting and facies stratigraphy as deep water and allochthonous biotic constituents within the lithoclasts and matrix indicate an early permian wolfcamp age the porous bioclast lithoclast rudstone floatstone facies contains a modest but geologically significant oil reservoir at gunnx field southwest reagan county production is from 10 ft 3 m of perforations in about 42 ft 13 m of pale yellow brown porous limestone with intercrystalline reduced and solution enlarged biomoldic intraskeletal fracture and possible intergranular porosity moldic porosity appears to be mainly within lithoclasts baroque dolomite is rare to common and partly to completely fills former void space in addition to calcite spar and micrite porosity generally ranges 7 18 the producing depth is about 9 450 ft 2 880 m and the trap is stratigraphic the cored sequence at gunnx is interpreted as a basin floor complex of debris flow sheets which contain the reservoir overlain by interbedded thin carbonate turbidites thin debris flow sheets and shale the lowermost debris flow at gunnx was deposited on a thin generally undated shale the lower part of which is late pennsylvanian at west world field the shale is interpreted as representing starved basin floor deposition and abruptly overlies shallow water strawn limestone in core at west world field carbonate detrital components in the limestone at gunnx were probably derived from a wolfcamp platform at least 10 mi 16 km west and were emplaced by various submarine gravity flow processes age and facies determinations from cores in the gunnx area significantly alter earlier stratigraphic interpretations made with wireline logs alone late paleozoic allochthonous carbonate facies may provide significant new reserves in the permian basin

intraseasonal oscillations in the global atmosphere i northern hemisphere and tropics abstract we have examined systematically oscillatory modes in the northern hemisphere and in the tropics the 700 mb heights were used to analyze extratropical oscillations and the outgoing longwave radiation to study tropical oscillations in convection all datasets were band pass filtered to focus on the intraseasonal is band of 10 120 days leading spatial patterns of variability were obtained by applying eof analysis to these is data the leading principal components pcs were subjected to singular spectrum analysis ssa ssa is a statistical technique related to eof analysis but in the time domain rather than the spatial domain it helps identify nonlinear oscillations in short and noisy time series in the northern hemisphere there are two important modes of oscillation with periods near 48 and 23 days respectively the 48 day mode is the most important of the two it has both traveling and standing components and is dominated by a zonal wavenumber two the 23 day mode has the spatial stru

authigenic k nh4 feldspar in sandstones a fingerprint of the diagenesis of organic matter abstract in arkosic sandstones of the san joaquin and los angeles basins presently at temperatures between 35 c and 174 c trace amounts of authigenic k nh4 feldspar are present as microfracture fillings and overgrowths on detrital k feldspar microchemical analyses of this authigenic phase reveal up to 80 mole buddingtonite the largest ammonium concentrations are observed in a sandy interval of the antelope shale 80 mole and in the stevens sands 50 mole of the san joaquin basin this latter unit was deposited as a turbidite in the organic rich fruitvale shale an equivalent of the antelope shale the lowest ammonium contents 0 16 mole are present in the shallow marine vedder sands and the marginal marin san joaquin formation in the same basin petrographic 18o 13c and 87sr 86sr analyses of a dolomite cement that postdates authigenic k nh4 feldspar indicate that the feldspar precipitated below 28 c in the zone of methanogenesis from pore waters with the same sr signature as sea water at the time of sedimentation authigenic k nh4 feldspar is thus an early diagenetic phase that crystallized prior to oil migration under anoxic conditions when organic matter releases ammonium the source of ammonium is bacterial decay of organic matter in the sandstones themselves and or in contemporaneous shales

interaction between intraseasonal oscillations of the midlatitude flow and tropical convection during 1979 northern summer the pacific ocean abstract it has been inferred and illustrated by many studies in terms of outgoing longwave radiation olr and velocity potential that energy is input into the intraseasonal oscillation through tropical cumulus convection especially over the monsoon region the existence of this low frequency oscillation of regional extratropical oscillation has been observed by other studies previous findings lead us to speculate upon a hemispheric interaction between tropical cumulus convection and extratropical circulation in terms of an intraseasonal time scale this study demonstrates that during the 1979 summer a coherent intraseasonal oscillation existed between cumulus convection and divergent circulation over the equatorial western pacific and mid pacific troughs moreover the intraseasonal oscillations of streamfunction associated with these troughs the tropical olr and the tropical field exhibit coherent eastward propagations based upon these two coherent relations it is hypothesized that a tro

petrography and diagenesis of silcrete from the kalahari basin and cape coastal zone southern africa abstract silcrete is widely distributed in southern africa and occurs both in genetic association with deeply weathered bedrock weathering profile type and as a significant component of the cenozoic kalahari beds where it has formed through silicification of a variety of continental deposits nonweathering profile type silcrete fabrics are classified into four major types gs grain supported skeletal quartz grains in contact f floating skeletal grains floating in matrix m matrix skeletal grains 5 of volume and c conglomeratic detrital component containing pebbles f and m fabric types are subdivided on the presence absence of glaebules replacement by silica of a precursor matrix can account for the development of all four fabric types but at least some gs and c fabr c silcretes have formed by passive silica precipitation in packing voids glaebules and colloform features predominantly composed of concentrations of anatase and iron oxide are common in weathering profile silcretes but their precise origin is uncertain authigenic silica is present as megaquartz microquartz length slow and length fast chalcedony predominantly in void fills cryptocrystalline silica and opal ct depending on the silica and ionic concentrations of pore waters ph and host sediment characteristics diagnostic petrographic features including glaebules colloform structures and chalcedonic vugh fills may be used in conjunction with geochemical data and sedimentary associations to interpret silcretes in the stratigraphic record with respect to weathering profile types formed in humid low ph environments or nonweathering profile types formed in high ph semiarid to arid environments

a lower palaeozoic shallow water sequence in the eastern european variscides sw poland provenance and depositional history the gackowa formation of inferred cambrian ordovician age is part of the metamorphosed pre variscan basement of the southern kaczawa mountains of the sudetes region south west poland previously variously interpreted as lavas tuffs and sandstones it is shown to consist of about 200 m of originally well sorted siliclastic sedimentary rocks within a sequence of predominantly mafic volcanic rocks four facies have been distinguished based on relict sedimentary structures and textures and these suggest that deposition took place on a storm dominated shelf mostly above the wave base the petrography detrital zircon morphologies and geochemistry suggest affinity with and derivation in large part from acid volcanic rocks at a comparable stratigraphic position in a separate tectonostratigraphic unit to the south the gackowa formation and its acid volcanic source rocks have a clear continental geochemical signature in contrast with the mantle derived basic bimodal volcanic rocks below and above it is suggested that the parent acid magma originated by crustal melting during the ascent of these mantle derived magmas a continental crust setting is inferred for the deposition of the gackowa formation sandstones thus suggesting a continental setting for the associated within plate basalts the entire volcanic sedimentary succession resembles elements of the lower palaeozoic of germany and all may have formed in an initial rift setting during late precambrian to ordovician times

fixed ammonium in clays associated with crude oils abstract the association of ammonium nh 4 silicates with organic rich sedimentary environments has stimulated interest in the chemical cycle of n and its possible application as an indicator of in situ organic maturation reactions or crude oil migration fixed nh 4 in clay minerals was determined from three hydrocarbon occurrences of similar depositional environment but different ages depth and thermal maturity to determine whether anomalously high nh 4 substitution occurs near mature hydrocarbons results show higher fixed nh 4 concentrations in marginally mature mudstones than in immature sediments the highest fixed nh 4 concentrations were found in clays from sandstone reservoirs containing migrated crude oil fixed nh 4 in clays from holocene oil seep sediments in the gulf of mexico continental slope offshore louisiana averages 0 08 wt and increases with depth in shallow cores 420 cm reflecting an early diagenetic trend that is apparently not influenced by migrating crude oil programmed pyrolysis shows that the sediments are thermally immature av t max 419 c high hydrogen index values av 359mg g are the result of biodegraded crude oil and a high oxygen index av 182mg g reflects the presence of authigenic carbonate fixed nh 4 averages 0 16 wt in wilcox group eocene mudstones enclosing two sandstone reservoirs at fordoche field onshore louisiana in comparison to these mudstones anomalously high nh 4 fixation appears to occur in reservoir clay minerals pyrolysis shows that the sediments are marginally mature for crude oil generation av t max 432 c average hydrogen index 187 mg g and oxygen index values 75 mg g are consistent with oil prone type ii and type iii kerogen increased pyrolysis production index values and solvent extraction shows the presence of migrated crude oil this suggests that a reaction which releases nh 3 during crude oil generation or migration is recorded bynh 4 substitution in clays fixed nh 4 and total organic carbon toc at fordoche field show no statistically significant correlation suggesting that nh 4 substitution in clay minerals is not simply related to the amount of organic matter in the section but is also influenced by the presence of crude oil once nh 4 has been fixed in clays it is a more stable hydrocarbon proximity indicator than pore fluid tracers because it is less influenced by later chemical or geological changes

the shape propagation and mean flow interaction of large scale weather systems abstract for a zonal average operator the eliassen palm flux provides a diagnostic of both eddy behavior and the feedback of the eddies onto the mean flow this paper addresses the diagnosis problem for other averaging operators and in particular for time averaging which has proved in recent years such a powerful means of viewing the three dimensional tropospheric flow the horizontal velocity correlation tensor gives a measure of the characteristic horizontal eddy shape at a point it also implies the direction of the group velocity relative to the mean flow in cases where such a concept is valid however the major emphasis here is on the mean flow feedback of eddies in this respect the eddy vorticity flux is determined by derivatives of the components of the anisotropic part of the tensor making a reasonable approximation allows the eddy vorticity flux convergence to be written in terms of e v 2 u 2 u v a simple interpretation of the mean flow feedback of eddies is then possible a sligh

biweekly and 21 30 day variations of the subtropical summer monsoon rainfall over the lower reach of the yangtze river basin abstract the lower reach of the yangtze river basin lyrb is located at the central region of the mei yu and baiu front which represents the subtropical east asian ea summer monsoon based on the newly released daily rainfall data two dominant intraseasonal variation isv modes are identified over the lyrb during boreal summer may august with spectral peaks occurring on day 15 the biweekly mode and day 24 the 21 30 day mode these two modes have comparable intensities and together they account for above about 57 of the total intraseasonal variance both isv modes exhibit baroclinic structures over the lyrb at their extreme phases however the genesis and evolutions associated with the two modes are different considering the genesis of their extreme wet phases over the lyrb the biweekly mode is initiated by a midlatitude jet stream vorticity anomaly moving southeastward while the 21 30 day mode is primarily associated with a low level westward propagation of an anticyclonic anomaly from

modulation of the madden julian oscillation on the energetics of wintertime synoptic scale disturbances numerous studies have devoted to energetic balance diagnosis of the synoptic scale disturbance ssd in the northern summer monsoon region but few work has concentrated on that during boreal winter this study investigated the energetics of the ssd associated with the eastward propagating madden julian oscillation mjo convection south of the equator during boreal winter the eddy kinetic energy is enhanced within and to the west of the mjo convection and is weakened to the east of it this is related to the barotropic energy conversion ck in lower and middle troposphere and conversion of eddy available potential energy ca in upper troposphere ck arises from interactions between ssd and mjo lower frequency flows the ssd in the vicinity of the mjo is characterized by a wavelike pattern with northwest to southeast tilt of elongated extrema of vorticity anomalies the mjo flow in lower troposphere is characterized by zonal convergence at the convection center and cyclonic anticyclonic circulation to the east west the lower frequency background flow is cyclonically sheared in the southern indian ocean more less ca to the west east is due to more less generated eddy available potential energy from diabatic effects the ssd contribute to the mjo eastward propagation through inducing a zonal asymmetry in nonlinear moisture advective tendency this accounts for 30 of the observed asymmetric intraseasonal moisture tendency