changes in occurrence of cold surges over east asia in association with arctic oscillation 1 it has been newly found that the occurrence of cold surges in east asia is significantly influenced by the arctic oscillation ao in the present study the events of cold surge are objectively determined based on several synoptic criteria and the phase dependency of its occurrences in association with the ao has been revealed during the negative ao phase the frequency of cold surge occurrence is relatively increased than that of neutral and positive ao phases the variation of upper level trough and jet stream over east asia and the siberian high in association of ao are suggested to explain the change of cold surge occurrences

isentropic analysis of polar cold airmass streams in the northern hemispheric winter abstractan analysis method is proposed for polar cold airmass streams from generation to disappearance it designates a threshold potential temperature t at around the turning point of the extratropical direct etd meridional circulation from downward to equatorward in the mass weighted isentropic zonal mean mim and clarifies the geographical distributions of the cold air mass the negative heat content nhc their horizontal fluxes and their diabatic change rates on the basis of conservation relations of the air mass and thermodynamic energy in the northern hemispheric winter the polar cold air mass below t 280 k has two main streams the east asian stream and the north american stream the former grows over the northern part of the eurasian continent flows eastward turns down southeastward toward east asia via siberia and disappears over the western north pacific ocean the latter grows over the arctic ocean flows toward the eastern coast of north america via hudson bay and disappears ov

upper devonian mississippian stratigraphic framework of the arkoma basin and distribution of potential source rock facies in the woodford chattanooga and fayetteville caney shale gas systems wireline logs were used to document the stratigraphic framework of upper devonian mississippian strata in the arkoma basin and maps of high gamma ray hgr log response were used to analyze the spatial distribution of potential source rocks in the woodford chattanooga and fayetteville caney shale gas systems the woodford chattanooga shale is a transgressive deposit that accumulated on an arid continental margin influenced by marine upwelling and minimal sediment influx a broad hgr depocenter along the southwestern margin of the basin includes two areas of higher accommodation containing the thickest hgr concentrations basin wide patterns of hgr likely reflect broad tectonic influence on accommodation the proportion of chert in the formation increases eastward and southward likely reflecting latitudinal and bathymetric influence on the accumulation of siliceous ooze the lower mississippian burlington sequence which lies between the two shale gas systems comprises carbonate ramp and distal shale deposits proximal ramp facies form an apron around the southern flank of the ozark uplift and grade radially basinward into distal facies an upper mississippian succession in the east includes lowstand deposits of the batesville delta which onlap the relict burlington ramp basinwide the succession includes the transgressive fayetteville caney shale overlain by regressive deposits of the proximal pitkin limestone and distal upper fayetteville arkansas and false caney oklahoma shale the hgr shale is concentrated in an area of intermediate accommodation on the western margin of the mississippi embayment and just basinward of the pitkin limestone pinchout in arkansas and in an area of relatively high accommodation in oklahoma

cement stratigraphy of pennsylvanian holder formation sacramento mountains new mexico cyclic strata of the holder formation virgilian new mexico were deposited across a pennsylvanian shelf to basin transition during a time when sea level fluctuated over tens of meters cement stratigraphy studies indicate abundant calcite precipitation from low temperature fresh water within shelf shelf crest and shelf edge marine limestones freshwater cementation occurred during 15 periods of intraformational subaerial exposure these early cements are least abundant in basin and lagoon limestones the distribution of the early cement zones suggests that cementation was controlled by paleotopography stratigraphic position below subaerial exposure surfaces lithology and configuration of the paleoaquifer system distribution of early calcite cements provides new data for interpretation of cycles diagenetic systems and porosity evolution in petroleum reservoirs trace element analyses support a low temperature freshwater origin for the early cements cement stratigraphy studies fluid inclusion analyses and trace element analyses indicate a later cement that occluded remaining limestone porosity precipitated from a sodium and calcium rich brine at a temperature of about 100 c stratigraphic reconstruction dates this cementation as cretaceous or later fluorescent oil filled fluid inclusions were trapped along fractures in the late cement indicating oil migration during or after late stage cementation

early cambrian ocean anoxia in south china the cause of the most marked changes in the evolution of life which define the first order stratigraphic boundary between the precambrian and the phanerozoic eon remains enigmatic and a highly topical subject of debate a global ocean anoxic event triggered by large scale hydrogen sulphide h 2 s release to surface waters has been suggested by wille et al on the basis of two data sets from south china and oman to explain the fundamental biological changes across the precambrian cambrian pc c boundary here we report a new precise shrimp u pb zircon age of 532 3 0 7 million years myr ago fig 1 for a volcanic ash bed in the critical unit that reflects the ocean anoxic event the lowermost black shale sequence of the niutitang formation in the guizhou province south china this age is significantly younger than the precise pc c boundary age of 542 0 0 3 myr ago approximately 10 myr younger than the extinction of the ediacaran fauna and thus challenging the view of a major ocean anoxic event having been responsible for the major changes in the direction of evolution at the pc c boundary

wille et al reply replying to s y jiang et al 10 1038 nature08048 2009 jiang et al 1 present a new shrimp u pb zircon age of 532 3 0 7 million years myr ago for an ash bed in the lowermost black shale sequence of the niutitang formation china and claim that the data presented in our recent paper2 do not firmly support the idea that the biological and environmental changes at the precambrian cambrian transition can be explained by a single global hydrogen sulphide h2s release event their new age seems to be supported by another recent shrimp investigation3 which indeed suggests that the chinese metal enriched sulphide layer does not represent the precambrian cambrian boundary and shows that the redox history of both basins oman and south china was much more complex

energetics and dynamics associated with two typical mobile trough pathways over east asia in boreal winter two dominant types of east asian mobile trough eamt are identified by a novel mobile trough detection algorithm the two major eamts likely pass through to the north and the south of lake baikal in this study both of synoptic and planetary time scales influences on east asia are studied for synoptic scale southern path of mobile trough shows a higher rate of intensification that of northern path southern path has stronger impact on southeast asia temperature fluctuation because of more southern pathway and stronger magnitude of wave train but duration of fluctuation is shorter in southern due to the downstream development for planetary scale the northern path shows a large warm anomaly over southeast asia and a cold anomaly over northeast asia which is associated with the northward shift of the jet stream the southern path shows a cold anomaly over east asia due to a northwesterly anomaly the forcing of high frequency eddy on low frequency eddy is estimated in terms of momentum and energy the reinforcement of high frequency eddy flux on low frequency variation can be observed in northern path but not in southern path the energy difference for two paths is also caused by the variations of barotropic and baroclinic conversion the energy tendency of interaction between two frequency eddies is only responsible for sustention of energy anomaly over southwestern japan

asymmetry and basin migration in the dead sea rift the dead sea depression sensu stricto forms the deepest continental part of the dead sea rift a transfer which separates the levanthine and arabian plates it is occupied by three distinct sedimentary bodies deposited in basins whose depocenters are displaced northward with time they are the continental red beds of the hazeva formation miocene the bira lido gesher marls and the exceptionally thick rocksalt of the sedom formation pliocene early pleistocene and the successive amora lisan and dead sea evaporites and clastics early pleistocene recent lengthwise and crosswise asymmetries of these sedimentary basins and their respective depocenters are due to leftlateral shear combined with anticlockwise rotation of the arabian eastern plate steeper faulting of the crustal eastern margin than of the western sedimentary margin and modification of depositional pattern by twice filling up of basins by hazeva red beds during late miocene pause of shear and by sedom rocksalt during pliocene marine ingression

a modified approach to estimating coal and coal gas resources example from the sand wash basin colorado the significant increase in united states gas production from coal beds over the past 5 yr has encouraged exploration and development of coal gas resources worldwide accurate assessment of coal and coal gas resources and delineating areas within basins containing the largest resources are important aspects of resource development previous resource studies may have overestimated or underestimated coal gas resources because the ash and density terms of resource equations were inconsistently or inappropriately considered in basins where coal analysis data are sparse coal gas resources are best calculated on an ash free basis the density contrast between ash forming minerals and organic matter is large enough that the weight percent ash is much larger than the corresponding volume percent therefore a correction factor relating weight percent ash free coal and ash yield determined from proximate analysis to ash free coal volume is required to accurately calculate coal gas resources rather than using one density value as has been done in previous studies our calculations require that bulk coal density including mineral matter be distinguished from ash free coal density coal and coal gas resources of the williams fork and fort union formations in the sand wash basin determined from modified resource equations are 291 billion tons short tons 264 billion t metric ton and 79 tcf footnote 2 2 tm3 these resources are significantly higher than previous estimates of basin resources of 34 5 billion tons 31 3 billion t of coal and 14 tcf 0 4 tm3 of coal gas the williams fork formation contains 79 of the coal and 95 of the coal gas resources reflecting greater maximum burial depth and higher gas contents the fort union formation contains 21 of the coal but only 5 of the coal gas resources coal gas resources are greatest in the central part of the basin where williams fork resources approach 70 gcf footnote mi sup 2 0 8 gm3 km2 in comparison the san juan basin the nation s most prolific coal gas producing basin has maximum coal gas resources approaching 35 gcf mi2 0 4 gm3 km2 the high resource density in the sand wash basin is due to greater net coal thickness rather than high gas content

reply to comment oman chronostratigraphy reply to comment by erwan le guerroue ruben rieu and andrea cozzi on geochronologic constraints on the chronostratigraphic framework of the neoproterozoic huqf supergroup sultanate of oman american journal of science v 307 p 1097 1145 le guerroue and others this issue highlight several questions regarding the neoproterozoic stratigraphy of oman in response to the publication of bowring and others 2007 1 we take this opportunity to respond to each of their points to reiterate some of the conclusions made in our original

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

influence of the madden julian oscillation on wintertime surface air temperature and cold surges in east asia 1 the variations of wintertime surface air temperature sat and the occurrences of cold surges over east asia in association with the madden and julian oscillation mjo are examined the mjo is defined as a combination of the two leading empirical orthogonal function modes of 850 and 200 hpa zonal winds and outgoing longwave radiation in the tropics the spatial pattern and magnitude of sat anomalies over east asia significantly change with respect to mjo phases composite analysis reveals that the mjo sat relationship is mainly affected by strong temperature advection in the lower troposphere in addition occurrences of cold surges are identified using objectively determined synoptic criteria and their relation to the mjo is analyzed most extreme cold surges occur when the mjo convection center is located over the indian ocean and it is suggested that mjo induced circulation anomalies may reinforce the amplification of normal cold surges to extreme cold surges

relationship between the arctic oscillation and cold surges over east asia abstract the present study reveals the changes in the characteristics of cold surges over east asia associated with the arctic oscillation ao based on circulation features cold surges are grouped into two general types wave train and blocking types the blocking type of cold surge tends to occur during negative ao periods that is the ao related polarity of the blocking type however the wave train type is observed during both positive and negative ao periods although the wave train features associated with negative ao are relatively weaker the cold surges during negative ao are stronger than those during positive ao in terms of both amplitude and duration the cold surges during positive ao in which the extent of effect is confined to inland china passes through east asia quickly because of weaker siberian high and aleutian low leading to short duration of these cold surges in contrast the cold surge during negative ao characterized by a well organized anticyclone cyclone couplet with high p

a numerical model for the formation of saline waters due to diffusion of dissolved nacl in subsiding sedimentary basins with evaporites abstract numerical modeling by a finite difference method incorporating the effects of vertical variations in pressure temperature salinity and porosity shows that mass transport by diffusion may be a major brine forming process in sedimentary basins containing halite beds vertical fluxes of dissolved nacl are greatest when the subsidence rate is slow at subsidence rates of 20 m m y 1 more than 250 m of salt can be dissolved over 150 m y at rapid subsidence rates such as 500 m m y 1 pore waters are advected downward so rapidly that although a diffusion front develops above the evaporite this front moves downward as the evaporite subsides and diffusive fluxes at shallow depths are thus low however under such conditions the pore water column becomes gravitationally unstable as a result of thermally induced density inversions and the potential for convective overturn is enhanced with accompanying advective salt flux upward although dissolution and diffusion of nacl are important processes in the burial history of evaporites they are not adequate by themselves to produce the regional salinity versus depth profiles that are actually observed in some sedimentary basins diffusion induced gradients progressively increase with depth whereas gradients actually observed in sedimentary basins tend to decrease with depth the difference is presumably due to the activity of other mass transport mechanisms such as advection convection and dispersion

hartshorne coal rank applied to arkoma basin coalbed methane activity oklahoma usa abstract coal rank generalized for all coal beds at or near the surface in the eastern oklahoma coalfield has been known since 1915 near the surface depths 305 m 1000 ft coals in arkoma basin coalbed methane cbm prospects was previously unknown a new hartshorne coal middle pennsylvanian rank map is based on mean maximum vitrinite reflectance values of 0 76 to 2 41 rmax from 70 coal samples from vertical depths of 0 surface to 1327 m 4355 ft hartshorne coal rank in the subsurface increases from high volatile bituminous to semianthracite from west to east in the arkoma basin in oklahoma bituminous rank boundaries changed considerably from earlier surface rank maps primarily by increasing the area of medium volatile bituminous rank coal in the subsurface and revealed a previously unknown semianthracite rank area this discrepancy is significant because the rank of deep 305 m 1000 ft coal resource assessments and cbm exploration projects have been based on shallow coal rank assignments a total of 2635 hartshorne hartshorne lower hartshorne and upper hartshorne cbm wells have been completed in oklahoma since 1988 most 1610 wells are horizontal with lateral lengths ranging from 4 to 1498 m 14 to 4914 ft an average of 669 m 2195 ft coal in most hartshorne cbm wells is medium volatile bituminous rank hartshorne coal is semianthracite rank in about 160 cbm wells in le flore county the four hartshorne cbm wells with the highest initial potential ip gas rates 48 to 65 thousand cubic meters per day mcmd 1 7 to 2 3 million cubic feet per day mmcfd are medium volatile bituminous rank from horizontal wells in haskell and pittsburg counties ip gas rates

hydrogen sulphide release to surface waters at the precambrian cambrian boundary changes in environmental conditions at the precambrian cambrian transition around 542 million years ago have been suggested as a possible explanation for the apparent rapid increase in abundance of multicellular organisms known as the cambrian explosion the nature of the environmental changes is still a matter of debate however wille et al now report molybdenum isotope signatures of black shales from two stratigraphically correlated sample sets with a depositional age of about 542 million years with the help of a box model of the oceanic molybdenum cycle they find that intense upwelling of hydrogen sulphide rich deep ocean water best explains the observed early cambrian molybdenum isotope signal this suggests that the early cambrian animal radiation may have been triggered by a major change in ocean circulation following a long period during which the ocean was stratified with sulphidic deep water this paper reports molybdenum isotope signatures of black shales from two stratigraphically correlated sample sets with a depositional age of around 542 million years the findings suggest that the early cambrian animal radiation may have been triggered by a major change in ocean circulation terminating a long period during which the proterozoic ocean was stratified with sulphidic deep water animal like multicellular fossils appeared towards the end of the precambrian followed by a rapid increase in the abundance and diversity of fossils during the early cambrian period an event also known as the cambrian explosion 1 2 3 changes in the environmental conditions at the precambrian cambrian transition about 542 myr ago have been suggested as a possible explanation for this event but are still a matter of debate1 2 3 here we report molybdenum isotope signatures of black shales from two stratigraphically correlated sample sets with a depositional age of around 542 myr we find a transient molybdenum isotope signal immediately after the precambrian cambrian transition using a box model of the oceanic molybdenum cycle we find that intense upwelling of hydrogen sulphide rich deep ocean water best explains the observed early cambrian molybdenum isotope signal our findings suggest that the early cambrian animal radiation may have been triggered by a major change in ocean circulation terminating a long period during which the proterozoic ocean was stratified with sulphidic deep water

evidence from apatite fission track analysis for regional cretaceous cooling in the ouachita mountain fold belt and arkoma basin of arkansas geologic note 1 a reconnaissance study involving apatite fission track analysis of surface paleozoic sedimentary and cretaceous intrusive rocks was undertaken to evaluate the low temperature thermal history of the ouachita mountain fold belt and arkoma basin of arkansas paleozoic rocks have apparent apatite fission track ages ranging from 184 or 12 ma to 95 or 11 ma with mean track lengths in the range of 12 95 or 0 17 micrometers to 13 51 or 0 13 micrometers indicating that these samples have undergone significant postdepositional annealing cretaceous samples have apatite fission track ages between 104 or 4 and 88 or 6 ma that are concordant with rb sr and k ar ages and mean track lengths in the range 14 69 or 0 16 micrometers to 15 36 or 0 10 microme ers indicating that these rocks cooled rapidly to paleotemperatures below 50 60 degrees c following their emplacement and have subsequently remained cool paleozoic strata of the ouachita mountain fold belt and arkoma basin in arkansas are inferred to have undergone regional cooling from paleotemperatures greater than 110 degrees c beginning in the early cretaceous to paleotemperatures generally less than 80 90 degrees c prior to the intrusion of alkaline plutons along the western margin of the mississippi embayment during the middle cretaceous whether regional cooling during the cretaceous was caused by uplift and erosion or whether a dramatic reduction in the paleogeothermal gradient was involved remains uncertain although a significant component of uplift and erosion is inferred from independent geological observations the results of this study indicate that paleozoic rocks of the ouachita mountain fold belt and arkoma basin of ar ansas were exposed to maximum paleotemperatures during late paleozoic burial prior to the emplacement of cretaceous plutons in the region

isotopic geochemistry of burial metamorphosed volcanogenic sediments great valley sequence northern california isotopic and mineralogic data from an 8500 m thick section of the great valley sequence northern california indicate that changes in the 18o values of authigenic minerals resulted from the conversion of smectite to a 10 a clay mineral as temperature increased with burial in the jurassic cretaceous outer arc basin the clay mineral assemblage in mudstone is characterized by a proportional increase of the 10 a clay mineral with increasing stratigraphic depth and by a depletion in the 18o value of the mixed layer smectite 10 a clay mineral with descending stratigraphic position from 21 9 to 15 5 smow modeling of the oxygen isotopic data from authigenic phases based on equilibrium fractionation during clay mineral diagenesis indicates that 18o values of calcite in mudstones and of calcite cements in sandstone precipitated along a temperature gradient of about 25 c km during maximum burial to about 6 7 km d values of the mixed layer smectite 10 a clay mineral range between 69 to 44 smow using temperatures calculated from the oxygen isotopic data the deuterium and oxygen isotopic data indicate that the smectite underwent late stage dehydration and probably buffered the composition of formation waters from sea water values to isotopic compositions of 18o 8 smow and d 25 smow the 13c values of calcite from mudstone and sandstone imply that crystallization of authigenic calcite was linked to organic diagenesis during which dissolved hcot 3 was continuously enriched in 13c as temperature increased with burial at the base of the sequence and immediately overlying the ophiolitic basement rocks several hundred meters of strata were altered by more oxygen depleted 18o 4 to 5 hydrothermal fluids emanating from the ophiolitic rocks probably at maximum burial depth

interannual variation of the east asian cold surge activity abstract the occurrence frequency of the east asian cold surge exhibits an interannual variation in concert with the el nino southern oscillation enso cycle that is the cold surge occurs more less frequently during warm cold enso winters because the cold surge high low dipoles are coupled with the upper level synoptic short waves any mechanism modulating the activity of these waves would affect the cold surge activity the streamfunction budget analysis in the short wave regime indicates that the development of the cold surge short wave train over east asia and the northwest pacific is modulated by the north pacific enso short wave train due to the coupling between the upper level cold surge short wave train and the surface cold surge dipole it is inferred from this streamfunction budget analysis that the interannual variation of the cold surge occurrence frequency is a result of this modulation

fluid inclusion evidence for solution mixing sweetwater mississippi valley type district tennessee fluid inclusions in fluorite from the appalachian mississippi valley type fluorite barite deposits of the sweetwater district in east tennessee indicate that the mineralizing solutions were sodium potassium chloride brines with an average temperature of 107 degrees c and an average salinity of about 16 equiv wt percent nacl a strong negative correlation of homogenization and freezing temperatures which was observed for inclusions from the southeast part of the district was interpreted to indicate that two solutions were present during fluorite deposition in this area a warm 160 degrees c less saline 12 solution and a cool 80 degrees c more saline 30 solution a connate source is considered likely for both solutions and the warm less saline solution appears to have come from at or beyond the east edge of the district mixing of these solutions could have caused ore deposition in the southeast belt although cooling probably caused deposition elsewhere in the district published data suggest that two similarly distinct solutions were present in the nearby east tennessee zinc district

fluid inclusion evidence for fluid mixing mascot jefferson city zinc district tennessee inverse correlation between homogenization temperature and salinity temperature of formation changes at near constant salinity and low salinity low to moderate temperature inclusion fluids are found in sphalerite formed in limestone an evolved basinal brine component was recognized by its characteristic temperature 100 degrees to 120 degrees c freezing point depression 1 fundamental chemical requirements for formation of pb zn ba f deposits from metal bearing basinal brines modified journal abstract

history of diagenetic fluids in a distant foreland area middle and upper pennsylvanian cherokee basin kansas usa fluid inclusion evidence abstract analysis of fluid inclusion data in diagenetic cements from pennsylvanian limestones and sandstones of the cherokee basin in southeastern kansas reveals the succession of diagenetic fluids in a distant foreland of the arkoma ouachita system this succession includes early low salinity 0 0 2 4 wt nacl eq fluids of meteoric affinity fluid i followed by low temperature na ca cl brines fluid ii with salinities between 8 4 and 24 1 wt nacl eq fluids i and ii were present in the system during precipitation of early stage calcite cements at temperatures less than about 50 c another na ca cl brine fluid iii with salinity up to 25 wt nacl eq was present in the system later at temperatures of maximum burial at least 80 85 c and higher fluid iii is followed by a na cl brine fluid iv with salinities about 19 21 wt nacl eq characterized by temperatures distinctly higher than maximum burial up to 150 c fluid iii and fluid iv were entrapped during precipitation of late stage baroque dolomite and fe dolomite in pennsylvanian limestones and late stage fe dolomite and ankerite in pennsylvanian sandstones the record of progression from fluid iii to fluid iv may have been partially obscured by thermal re equilibriation of some inclusions during migration of fluid iv fluids with na ca cl chemistry fluid ii and iii were either indigenous subsurface fluids of the cherokee and arkoma basins or might have originated as reflux fluids in a permian evaporitic basin of central kansas later na cl brine fluid iv originated in deeper parts of the arkoma ouachita system and might have acquired their salinity by dissolution of hypothetical salts buried beneath the ouachitas temperatures recorded by fluid inclusions in late diagenetic carbonates are 20 60 c higher than those calculated for the maximum burial of the studied section this thermal anomaly suggests an advective heat transfer from the arkoma ouachita system onto the shelf of the cherokee basin related to the invasion of late diagenetic fluids

geologic provinces of oklahoma the geologic provinces of oklahoma are mainly the product of tectonics and attendant sedimentation of pennsylvanian age most boundaries are structural thus the provinces map is a generalized tectonic map permian and post paleozoic strata tend to mask those structures but most of those strata have been removed by erosion except in the anadarko basin and the wichita uplift provinces the location of most of oklahoma s oil and gas resources are either influenced by or are the direct result of pennsylvanian tectonics and sedimentation patterns therefore the present study also defines provinces in the subsurface on the basis of geological criteria the authors have attempted to use the originally published names for the recognized provinces however we also have used the most geologically correct names i e we recommend abandonment of the term nemaha ridge because it is not a geologic term nor does it describe the feature accurately

diagenetic history of eocene wilcox sandstones south central texas abstract sandstones and shales of the lower eocene wilcox group extend from outcrop to depths greater than 5 km where temperatures exceed 200 c eight authigenic minerals have been identified quartz kaolinite calcite ankerite and albitized plagioclase are volumetrically significant whereas chlorite illite albite overgrowths and dolomite are present only in trace amounts quartz kaolinite and ankerite cements are present over the entire depth range sampled 1528 to 4446 m calcite cement occurs only in sandstones shallower than 3300 m albitized plagioclase is the predominant feldspar in samples deeper than 2600 m whereas detrital potassium feldspar has been completely dissolved out of sandstones deeper than about 3200 m no systematic variations in the chemical composition of calcite with depth no zoning within calcite or ankerite and no compositional differences between pore filling and grain replacing calcite or ankerite were found calcite cements have 87 sr 86 sr ratios generally less than 0 708 whereas ankerite cements are significantly enriched in 87sr the oxygen isotopic composition of carbonate cement ranges between 9 and 14 pdb for calcite and between 8 and 12 for ankerite with no systematic variation with depth calculated 18o values for authigenic quartz and kaolinite range from 22 to 31 smow and from 14 to 17 respectively volumetrically important amounts of authigenic quartz and kaolinite precipitated during early burial before calcite cementation secondary porosity generation or smectite to illite transformation in encasing shales the isotopic composition of strontium in calcite cement shows most of it to be of eocene or older marine carbonate origin ankerite cementation followed the generation of secondary porosity and occurred after the products of organic maturation and shale diagenesis plagioclase albitization or potassium feldspar dissolution significantly affected the sandstone pore water system

comparison of the synoptic conditions in midlatitudes accompanying cold surges over eastern asia for the months of december 1974 and 1978 part i monthly mean fields and individual events abstract east asian cold surges during two periods of contrasting intensity december 1974 strong and december 1978 weak are studied it is shown that the midlatitude mechanisms initiating cold surges during both months are quite similar in nature synoptic scale short waves passing through the long wave trough position near the east asian coast act to release the cold air southward from the main reservoir over eastern siberia dynamic descent is initiated by these synoptic scale waves entering the northwesterly flow on the western side of the long wave trough anchored on the coast this is the descent center in the local direct circulation in the entrance region of the east asian jet maximum at 200 mb the frequency and intensity of the cold air surges for a given month depend on the large scale circulation pattern the average flow over asia for december 1974 and 1978 presents a contrast with respect to ridging over the midcontinent in december 1978 the flow was characterized by a low zonal inde

a mechanism for african monsoon breaks mediterranean cold air surges 1 surges of cold air from the mediterranean into northern africa during the boreal summer are documented and their influence on monsoon breaks is analyzed using tropical rainfall measuring mission rainfall estimates and reanalysis products between 1998 and 2006 6 10 cold air surges occurred each summer with low level temperature anomalies ranging from less than 1 k to over 6 k composite analysis indicates that cold air surges over northern africa persist for 2 10 days and travel equatorward at approximately 5 5 m s 1 which is 0 5 1 5 m s 1 faster than the observed climatological low level meridional flow northern african cold surges have characteristics similar to surges observed elsewhere in the world including a hydrostatically induced ridge of surface pressure and an amplified upper tropospheric ridge trough pattern the african cold surge is preceded by the passage of a shortwave trough and an intensification of the upper tropospheric subtropical westerly jet streak over the mediterranean sea these events are associated with increased confluence in the jet entrance region over the central mediterranean an enhanced direct secondary circulation subsidence and low level ageostrophic northerly flow over northeastern africa composite analysis shows that the passage of a cold surge is associated with an enhancement in convective activity over southern algeria western niger northern mali and mauritania 2 to 5 days before the surge reaches the eastern sahel 17 5 n when northeasterly flow channeled between the atlas and ahaggar mountains strengthens and transports relatively moist air from the western mediterranean and eastern north atlantic over the region and increases moisture convergence over western africa north of 20 n over the eastern sahel of sudan and eastern chad the composite results reveal a break in convective activity and decrease in low level convergence when the surge arrives that persists for about 6 days these results offer great promise for improving the short range prediction of rainfall over northern africa

goethite bearing brine inclusions petroleum inclusions and the geochemical conditions of ore deposition at the jumbo mine kansas abstract petroleum bearing fluid inclusions occur in sphalerite calcite dolomite and barite at the jumbo mine a mississippi valley type deposit in eastern kansas in addition to petroleum na ca mg fe chloride brines were present during deposition of calcite and sphalerite in which primary inclusions contain 23 equivalent wt nacl dolomite and barite hosted inclusions are more dilute possibly because of mixing between hydrothermal fluids and groundwater during mineralization primary oil inclusions in sphalerite have homogenization temperatures t h between 85 and 95 c aqueous inclusions have t h values ranging from 90 to 130 c for sphalerite to below 50 c for barite primary brine inclusions in calcite at the jumbo mine contain goethite apparently as a daughter mineral although it is possible that the goethite formed as a result of diffusion of h 2 from the inclusions like the hematite daughter described by roedder and skinner 1968 from bingham utah goethite has also been tentatively identified in inclusions from the fletcher mine of missouri if goethite is a true daughter phase it implies the presence of oxidized fluids during mineralization this suggests that ore deposition resulted from interactions between hydrothermal fluids and dilute groundwater e g by dilution or cooling of ore fluids or oxidation of organometallic complexes that may have transported metal constituents

thermal maturity of carboniferous strata ouachita mountains the ouachita mountains a relatively untested potential hydrocarbon province contain a thick paleozoic section of apparently favorable source beds reservoir beds and trap configurations to estimate the thermal maturity of these strata vitrinite reflectance was measured on 89 samples collected mostly from carboniferous rocks from throughout the ouachita outcrop area thermal maturity contours generally parallel structural grain in the western two thirds of the ouachitas reflectance values in oil range from 3 0 in the core area in oklahoma and from about 1 0 to 3 0 in analogous positions in arkansas older strata on upthrown sides of thrust faults are more thermally mature than younger strata on downthrown sides in the eastern one third of the outcrop belt thermal maturities are significantly higher 2 0 5 0 ro and thermal maturity contours cut obliquely across structural grain strata on either side of thrust faults display identical levels of maturity in the western two thirds of the ouachitas sedimentary and tectonic burial have been the major influences of thermal maturation although a mesozoic thermal overprint has increased levels of maturity in arkansas throughout this area strata are within the oil and wet gas windows the anomalous levels and patterns of thermal maturity in the eastern third of the ouachitas are probably the result of a thermal overprint related to mesozoic rifting and intrusive activity in the mississippi embayment this thermal overprint has elevated the maturity of strata in most of this area above the level of hydrocarbon preservation although maturities within the dry gas window are retained locally