very short term earthquake precursors from gps signal interference based on the 2013 nantou and rueisuei earthquakes taiwan abstract we set up a gps network with 17 continuous gps cgps stations in southwestern taiwan to monitor real time crustal deformation we found that systematic perturbations in gps signals occurred just a few minutes prior to the 2013 nantou ml 6 5 and rueisuei ml 6 4 earthquakes in taiwan the anomalous pseudorange readings were several millimeters higher or lower than those in the background time period these systematic anomalies were found as a result of interference of gps l band signals by electromagnetic emissions ems prior to the mainshocks the ems may occur in the form of harmonic or ultra wide band radiation and can be generated during the formation of mode i cracks at the final stage of earthquake nucleation we estimated the directivity of the likely em sources by calculating the inner product of the position vector from a gps station to a given satellite and the vector of anomalous ground motions recorded by the gps the results showed that the predominant inner product generally occurred when the satellite was in the direction either toward or away from the epicenter with respect to the gps network our findings suggest that the gps network may serve as a powerful tool to detect very short term earthquake precursors and presumably to locate a large earthquake before it occurs nevertheless a direct measurement of ems at the site of the gps array is required in future studies to confirm this hypothesis

abiogenic hydrocarbon isotopic signatures in granitic rocks identifying pathways of formation abstract the stability and isotopic composition of hydrocarbons formed in the mantle are controversial subjects knowing the range in isotopic compositions of abiogenically derived hydrocarbons is important for recognising biological signatures in ancient and extra terrestrial materials in an effort to enhance this database stable isotope results are reported here for hydrocarbon bearing fluid inclusions hosted in two peralkaline igneous complexes from lovozero russia and strange lake canada based on the distribution of isotopic compositions we propose three pathways for abiogenically generated hydrocarbons type 1 13cch4 13cco2 and 13cc2 represents mantle derived hydrocarbons generated in equilibrium with hyperagpaitic magmas in the upper mantle and suggests that mantle ch4 and c2h6 13c and 2h could have values of 5 3 and 112 and 10 8 and 162 respectively type 2 13cco2 13cch4 13cc2 represents fischer tropsch type hydrocarbon generation in quartz bearing peralkaline rocks with co2 as the initial magmatic gas phase for type 2 13cco2 values are 2 whereas 13cch4 and 2hch4 values range from 32 to 20 and 170 and 160 respectively the 13cc2h6 values are slightly lower than associated 13cch4 values type 3 13cco2 13cch4

palaeoproterozoic evaporites in fennoscandia implications for seawater sulphate the rise of atmospheric oxygen and local amplification of the δ13c excursion this paper addresses global oxygenation and establishment of a marine sulphate reservoir in the palaeoproterozoic we report syn depositional marine anhydrite containing pseudomorphs after ca sulphates as widespread throughout the tulomozero formation in the se fennoscandian shield implying that surface waters were oxidized and a large so42 marine reservoir was developed as early as 2100 ma the ca sulphates and associated magnesite and halite precipitated syn depositionally from oxidized evolved and modified seawater in coastal playa sabkha and intertidal flat settings sr 87 sr 86 and delta 13 c of associated c 13 rich stromatolitic dolostones were environmentally controlled with the highest ratios occurring in playa and sabkha carbonates the results imply that the palaeoproterozoic delta 13 c carb excursion was amplified by 8 by local environmental factors and calls into question many observations of putative delta 13 c global signals reported previously from similar palaeoproterozoic evaporitic dolostones the local environmental amplification can explain a large regional and intercontinental delta 13 c discrepancy observed in synchronous carbonates

anomalous pre seismic transmission of vhf band radio waves resulting from large earthquakes and its statistical relationship to magnitude of impending earthquakes summary to confirm the relationship between anomalous transmission of vhf band radio waves and impending earthquakes we designed a new data collection system and have documented the anomalous vhf band radio wave propagation beyond the line of sight prior to earthquakes since 2002 december in hokkaido northern japan anomalous vhf band radio waves were recorded before two large earthquakes the tokachi oki earthquake mj 8 0 mj magnitude defined by the japan meteorological agency on 2003 september 26 and the southern rumoi sub prefecture earthquake mj 6 1 on 2004 december 14 radio waves transmitted from a given fm radio station are considered to be scattered such that they could be received by an observation station beyond the line of sight a linear relationship was established between the logarithm of the total duration time of anomalous transmissions te and the magnitude m or maximum seismic intensity i of the impending earthquake for m4 m5 class earthquakes that occurred at depths of 48 54 km beneath the hidaka mountains in hokkaido in 2004 june and 2005 august similar linear relationships are also valid for earthquakes that occurred at different depths the relationship was shifted to longer te for shallower earthquakes and to shorter te for deeper ones numerous parameters seem to affect te including hypocenter depths and surface conditions of epicentral area i e sea or land this relationship is important because it means that pre seismic anomalous transmission of vhf band waves may be useful in predicting the size of an impending earthquake

assessing effects of sulfate minerals on petroleum generation in sedimentary basins using hydrous pyrolysis i light alkanes abstract a series of hydrous pyrolysis experiments were conducted to assess the role of sulfate minerals on the chemical and isotopic compositions of light hydrocarbons generated during thermal degradation of kerogen the shale source rock with low maturity tmax 425 c from eagle ford formation in southeast texas was used in the experiments at 330 c for the duration of 72 h while the abundance of gypsum in each experiment varies from 0 0 5 to 1 wt under experimental conditions the positive effect of gypsum on the yields of gaseous alkanes c1 c4 and co2 has been explicitly observed with an exponential relationship between the yield of each gas and the amount of gypsum while the relative abundance of c2 c4 alkanes has shown an increasing trend with gypsum the gas dryness c1 c1 4 however decreased from 73 1 with no gypsum to 49 6 with gypsum of 1 wt it was attributed to lower overall yields and corresponding higher increased generation rates of c2 c4 alkanes than methane through thermal cracking of kerogen and other organic compounds the carbon isotope value of each alkane reached the highest in the experiment with 1 wt gypsum compared to the experiment without gypsum there was an increase of 11 5 for the 13c value of methane with 1 wt gypsum the extent of this 13c enrichment between experiments with different amount of gypsum became less for c2 to c4 the 13c value of co2 was the highest among generated gases ranging from 4 7 to 2 1 combined with chemical compositions of gases it suggested that enhanced thermal cracking reactions were predominant in generation of light alkanes with the presence of gypsum whereas dissolution of carbonates was the main source of co2 the reactions involving thermochemical sulfate reduction tsr were minor if present under experimental conditions most likely due to the small quantity of gypsum up to 1 wt and neutralization of acidity by carbonates nonetheless the changes in chemical and isotopic compositions of light alkanes which were ultimately caused by the presence of gypsum need to be incorporated into geochemical proxies for assessing source rocks maturation in particular and their generation potential

multisatellite observations of an intensified equatorial ionization anomaly in relation to the northern sumatra earthquake of march 2005 here we report multisatellite observations of ionospheric disturbances in relation to the occurrence of the m8 7 northern sumatra earthquake of 28 march 2005 the demeter detection of electro magnetic emissions transmitted from earthquake regions and champ challenging minisatellite payload satellite data were investigated to find possible precursory and postevent phenomena it was found that eia equatorial ionization anomaly strength expressed in the apex height derived from the champ plasma density profile was intensified along the orbits whose longitudes were close to the epicenter within about a week before and after occurrence of the earthquake increases in electron and o density along the orbits close to the epicenter were also observed in the demeter measurements the normalized equatorial plasma density derived from the demeter measurements showed intensification about a week before and after the earthquake reaching maximum the day after the shock and afterward disappearing in addition similar behavior of the eia enhancements related to the m8 0 pisco earthquake of 15 august 2007 was observed surveys of space weather and geomagnetic activities excluded the possibility that these fluctuations were caused by changes in space weather or by a geomagnetic storm statistical analyses of the longitudinal variation revealed that the eia was enhanced in the west of the epicenter and reduced in the east of the epicenter and this fits the increased conductivity model based on these observations we proposed a revised view of seismo ionospheric coupling in the region of the geomagnetic equator to explain the eia features observed in this study

lower triassic sulphur isotope curve of marine sulphates from the dolomites n italy abstract 6 evaporite samples from the latest permian to the late lower triassic have been sampled at marine carbonate sections in the southern alps the sulphur isotope ratio of the sulphate has been determined to learn about the changes of the marine 34s ratio during the investigated period as it is known from the literature that a profound change from depleted to heavily enriched 34s values occurred within the lower triassic the carbonates from the same sections have been analysed for their carbon isotope pattern as the carbon isotope curve of the lower triassic has a very distinct pattern it enables the stratigraphic location of the evaporite layers in the section thus it can be shown that the change in 34s already occurred at the dienerian smithian boundary or within the dienerian stratification and re mixing of ocean water are the most plausible interpretations for the observed isotope patterns

free hydrogen hydrocarbon gases from the lovozero loparite deposit kola peninsula nw russia abstract the lovozero nepheline syenite massif in the north eastern fennoscandian shield well known to mineralogists and petrologists is also interesting with its high contents of hydrogen hydrocarbon gases in different forms of presence which is untypical of magmatic rocks the article systematizes and generalizes little known and unpublished data on the composition location character and scale intensity of the free gases fg emission within a major loparite deposit confined to the massif 4 and 2 are dominant in the fg composition the molecular weight distribution of hydrocarbon gas components corresponds to the classic anderson schulz flory distribution with a steep gradient carbon and hydrogen of the gases are characterized by rather heavy isotope compositions becoming lighter from the transition of methane to ethane the fg volume has been estimated as 0 2 1 6 m 3 of gas per 1 m 3 of undisturbed rock the gas recovery of walls in underground workings has been up to 0 2 ml min m 2 for 4 and 0 5 ml min m 2 for 2 in several years after their heading the discharge of some shot holes that characterizes the gas emission intensity 1 8 2 m deep and 40 mm in diameter is up to 300 ml min but its 1 2 orders lesser values dominate the discharge time in some sections varies from several days to 20 years the overpressure of gases towards the air mainly does not increase 100 hpa sometimes reaching 120 kpa it has been defined that fg distribute irregularly at the distance of centimeters to hundreds of meters and their composition and particularly emission intensity perform different temporal fluctuations the abiogenic origin of fg has been proposed with fg appearing as a mixture of gases in various proportions a gases remaining in microfissures at the massif s consolidation after the capture by fluid inclusions and those lost during degassing and b gases occurred in mechanic chemical reactions partial emission and concentration of occluded and diffusely scattered gases under the unstable stress strain mode of the rock mass combustible and explosive hydrogen hydrocarbon fg can accumulate in the air of underground workings and cause accidents disrupting the workflow the background for using characteristics of spatial temporal variations of the fg emission as precursors of dangerous geodynamic phenomena has been indicated

the origin of decoupled carbonate and organic carbon isotope signatures in the early cambrian ca 542 520 ma yangtze platform abstract the early cambrian ca 542 520 ma strata in south china record two prominent negative carbonate carbon isotope 13ccarb excursions of early nemakit daldynian n d and early tommotian ages across each of these excursions carbonate and organic carbon isotopes 13ccarb and 13corg are strongly decoupled regional correlation across a shelf to basin transect shows lateral heterogeneity of 13corg during the early middle n d but more homogenized 13corg values across the basin during the late n d and tommotian the temporal and lateral variations in 13corg suggest that decoupled 13ccarb and 13corg across the n d 13ccarb excursion were possibly caused by diagenetic alteration of organic matter and or amplification of detrital organic carbon isotope signature in low toc carbonates in contrast decoupled 13ccarb and 13corg of the upper n d and tommotian were likely resulted from chemoautotrophic methanotrophic biomass contribution to toc in organic rich black shale and carbonates the decoupled 13ccarb 13corg pattern from the lower n d strata ca 542 ma shows striking similarities with those from the basal ca 635 ma and upper ca 551 ma doushantuo formation in all three cases decoupled 13ccarb 13corg are seen in organic poor carbonates toc 0 1 and coupled 13ccarb 13corg occur in organic rich black shale and carbonates at the end of the negative 13ccarb excursion these similarities suggest that the shift from decoupled to coupled 13ccarb 13corg has no causal link with the terminal oxidation of a large oceanic doc reservoir given the pervasive anoxia euxinia in ediacaran early cambrian oceans local doc rich environments may have been common but a large oceanic doc reservoir capable of buffering the 13c of marine organic matter requires independent evidence

isotopic composition of disseminated sulfur in precambrian sedimentary rocks abstract isotopic analyses of trace sulfur in precambrian carbonates and clastic sedimentary rocks support the results of previous studies which have shown that 34s measurements of archean sedimentary sulfur cluster mostly around mantle like values and that a significant overall dispersion of 34 s 32 s ratios commenced at about 2 7 ga ago the outstanding feature of the proterozoic record is the predominance of heavy 34ssulfide values mostly in excess of 0 cdm consideration of these data in combination with the sparse 534s record for proterozoic sulfates suggests that 34ssulfide sulfide may have been smaller than was the case during the phanerozoic a possible scenario that is compatible with the above data is based on a proposition that the terrestrial exogenic sulfur cycle evolved in a tripartite manner in the archean it was coupled to and controlled by the magmatic endogenic cycle the proterozoic for the most part represents a transitional stage into a phanerozoic like exogenic cycle the latter essentially decoupled from its endogenic counterpart and its redox balance maintained and mediated by the biosphere the indication that the mean combined 34s of proterozoic sulfate and sulfide may have significantly exceeded the phanerozoic mean value of 2 cdm is enigmatic and poses problems for balance considerations

geochemistry of low molecular weight hydrocarbons in hydrothermal fluids from middle valley northern juan de fuca ridge abstract hydrothermal vent fluids from middle valley a sediment covered vent field located on the northern juan de fuca ridge were sampled in july 2000 eight different vents with exit temperatures of 186 281 c were sampled from two areas of venting the dead dog and odp mound fields fluids from the dead dog field are characterized by higher concentrations of nh3 and organic compounds c1 c4 alkanes ethene propene benzene and toluene compared with fluids from the odp mound field the odp mound fluids however are characterized by higher c1 c2 c3 and benzene toluene ratios than those from the dead dog field the aqueous organic compounds in these fluids have been derived from both bacterial processes methanogenesis in low temperature regions during recharge as well as from thermogenic processes in higher temperature portions of the subsurface reaction zone as the sediments undergo hydrothermal alteration carbon dioxide and hydrocarbons are released to solution as organic matter degrades via a stepwise oxidation process compositional and isotopic differences in the aqueous hydrocarbons indicate that maximum subsurface temperatures at the odp mound are greater than those at the dead dog field maximum subsurface temperatures were calculated assuming that thermodynamic equilibrium is attained between alkenes and alkanes benzene and toluene and carbon dioxide and methane the calculated temperatures for alkene alkane equilibrium are consistent with differences in the dissolved cl concentrations in fluids from the two fields and confirm that subsurface temperatures at the odp mound are hotter than those at the dead dog field temperatures calculated assuming benzene toluene equilibrium and carbon dioxide methane equilibrium are similar to observed exit temperatures and do not record the hottest subsurface conditions the difference in subsurface temperatures estimated using organic geochemical thermometers reflects subsurface cooling processes via mixing of a hot low salinity vapor with a cooler seawater salinity fluid because of the disparate temperature dependence of alkene alkane and benzene toluene equilibria the mixed fluid records both the high and low temperature equilibrium conditions these calculations indicate that vapor rich fluids are presently being formed in the crust beneath the odp mound yet do not reach the surface due to mixing with the lower temperature fluids

carbon isotope fractionation during methane dominated tsr in east sichuan basin gasfields china a review thermochemical sulfate reduction is considered to result in h2s 10 and high dryness coefficient values in the lower triassic and upper permian carbonate reservoirs in the ne sichuan basin the gases pro duced from gasewater transition and water intervals were measured to have h2s higher than 30 and are calculated to have significantly higher h2s and co2 contents than a gas produced from a gas interval and thus are not used to reflect tsr extents methane and ethane were shown to shift positively in carbon isotopes as a result of tsr however the fractionation has not quantitatively described a loga rithmic relationship is found to give the best fit for methane d 13 c 1 and 1 h2s

carbon isotope effect during abiogenic oxidation of methane abstract the oxidation of methane during flow over cuo and fe2o3 has been examined in the temperature range of 400 650 c the reaction rate and carbon isotope fractionation are dependent upon the choice of oxide and temperature the activation energy is lower for hematite 8 0 kcal mole 1 than for cupric oxide 16 6 kcal mole 1 the measured ratios of the isotopic rate constants k12 k13 were found to have temperature dependences given by 103 1 2 93 106 t2 8 11 cupric oxide 103 1 7 44 106 t2 6 56 hematite abiogenic oxidation of methane is probably a significant mechanism for fractionating carbon isotopes in nature

stratification and mixing of a post glacial neoproterozoic ocean evidence from carbon and sulfur isotopes in a cap dolostone from northwest china abstract to improve our knowledge about the geochemical and environmental aftermath of neoproterozoic global glaciations we analyzed stable isotopes 13 c 18 o 34 s and elemental concentrations ca mg s sr fe and mn of the 10 m thick zhamoketi cap dolostone atop the tereeken diamictite in the quruqtagh area eastern chinese tianshan available chemostratigraphic data suggest that the tereeken diamictite is probably equivalent to the marinoan glaciation our new data indicate that organic and carbonate carbon isotopes of the zhamoketi cap dolostone show little stratigraphic variations averaging 28 2 and 4 6 respectively in contrast sulfur isotopes show significant stratigraphic variations carbonate associated sulfate cas abundance decreases rapidly in the basal cap dolostone and 34 s cas composition varies between 9 and 15 in the lower 2 5 m in the overlying interval cas abundance remains low while 34 s cas rises 5 and varies more widely between 10 and 21 the range of 34 s py of the cap dolostone overlaps with that of 34 s cas but direct comparison shows that 34 s py is typically greater than 34 s cas measured from the same samples hypotheses to explain the observations must account for both the remarkable sulfur isotope enrichment of pyrites and the inverse fractionation we propose that cas and pyrite were derived from two isotopically distinct reservoirs in a chemically stratified basin or a basin with a sulfate minimum zone in this model cas was derived from shallow oxic surface waters with moderate sulfate concentration and depleted in 34 s due to the post glacial influx of sulfur from continental weathering in contrast pyrite was derived from anoxic bottom waters or a sulfate minimum zone with low sulfate concentration and 34 s enrichment due to long term syn glacial sulfate reduction the rapid shift in cas abundance and sulfur isotope composition within the cap dolostone is interpreted to reflect the mixing of the two reservoirs after initial deglaciation comparison with other post marinoan cap carbonates shows significant spatial heterogeneity in 34 s cas which together with strong temporal variation in 34 s cas points to generally low sulfate concentrations in post marinoan oceans

atmospheric anomalies observed during earthquake occurrences 1 appearance of anomalies in the atmosphere before earthquakes eqs has been verified through observation of anomalous transmission of vhf electromagnetic em waves beyond line of sight anomalous increase of the received intensity for a few minutes several hours on a day was identified by the previous 15 day running median and its inter quartile range the cross correlation between the eq occurrences and the anomalies shows that the appearance of anomalies was significantly enhanced within 5 days before m 4 8 eqs the one day average number of the anomaly appearance within 5 days was found 2 4 times larger than that of other days through the polarization measurement of the received em waves the anomalies were found to occur in the atmosphere index terms 6904 radio science atmospheric propagation 6964 radio science radio wave propagation 7223 seismology seismic hazard assessment and prediction citation fujiwara h m kamogawa m ikeda j y liu h sakata y i chen h ofuruton s muramatsu y j chuo and y h ohtsuki 2004 atmospheric anomalies observed during earthquake occurrences geophys res lett 31 l17110

chemical and carbon isotopic fractionations of gaseous hydrocarbons during abiogenic oxidation abstract the variations of chemical and carbon isotopic compositions in gaseous hydrocarbons upon abiogenic oxidation by sulfates hematite and both in laboratory studies were clearly demonstrated through a unique two step experimental approach in the first step a large number of small gold capsules containing gaseous hydrocarbons were prepared by kerogen pyrolysis experiments which were conducted under the same condition 450 c and 50 mpa for 72 h using the same kerogen the analytical results demonstrated that the chemical and carbon isotopic compositions of gases were almost identical among the capsules in the second step each of these gaseous hydrocarbon bearing capsules along with mineral oxidant hematite or magnesium sulfate heptahydrate or both and deionized water 15 of the amount of the oxidant was placed into a large gold capsule after welding sealing the small gaseous hydrocarbon bearing capsule was forced to leak while the large capsule remained undamaged by compressing the large capsule from the outside at the position where this small capsule was located then these large capsules containing gas and mineral reactants were heated isothermally at 350 c and 50 mpa for 72 144 216 and 288 h respectively the results of the oxidation experiments with increasing heating time can be outlined as follows 1 the amount of methane remained almost unchanged in the experiments using hematite and the mixed oxidants hematite mgso4 while it increased substantially in the experiment using mgso4 after 72 h indicating methane was one of the final products of c2 oxidation 2 the amounts of c2 c5 hydrocarbons decreased consistently and more rapidly in the experiment using mgso4 than that using hematite and the mixed oxidants 3 the oxidation rates of gas hydrocarbons increased with increasing carbon number of hydrocarbons 4 the oxidation rates of i butane and i pentane were substantially higher than those of the corresponding n butane and n pentane 5 the amount of h2s increased substantially in the experiment using mgso4 whereas it was below the detection level in the experiments using hematite and the mixed oxidants 6 the 13c values of c1 c5 hydrocarbons became less negative and the isotopic fractionation extent increased with increasing carbon number of hydrocarbons and oxidation extent 7 carbon isotopic fractionation factor k12 k13 decreased with increasing oxidation rate of gas hydrocarbons and 8 the rate of thermochemical sulfate reduction tsr was strongly dependent upon the presence and concentrations of h2s

a molecular and isotopic geochemical study of meso to neoproterozoic 1 73 0 85 ga sediments from the jixian section yanshan basin north china abstract this paper systematically describes the molecular and isotopic characteristics of meso to neoproterozoic 1 73 0 85 ga sediments from the jixian section yanshan basin north china a correlation is made between molecular fingerprints and paleoenvironmental and paleontologic data acquired from these strata the agreement between these parameters suggest that the biomarkers preserved in these proterozoic sediments are good indicators of the evolution of the paleoenvironment and early life in the yanshan basin the fact that extended regular isoprenoids c20 were detected in most of the studied samples suggest a sustained lipid input to sedimentary organic matter from halophiles and other possible archaebacteria through meso to neoproterozoic two dehydroabietin isomers i e 18 and 19 norabieta 8 11 13 trienes were unexpectedly present in these samples which provides evidence suggesting that the compounds with abieta structure could be derived from primitive organisms such as algae the stable carbon isotope characteristics of kerogen and coexisting carbonate show a rapid decline in atmospheric co2 concentration from 1 73 to1 58 ga and a stable concentration afterwards the difference c in isotopic composition between carbonate and associated kerogen lies in zonal variations along the stratigraphic sequence which can be attributed to the alternations of marine transgressions and regressions that occurred in the yanshan basin during the proterozoic the carbon isotope relationships between kerogen and alkanes from these strata are consistent with the hypothesis that before 1 4 ga both n alkanes and isoprenoids had been derived mainly from heterotrophic halophiles and other archaebacteria but after that only isoprenoids originated from archaebacteria whereas n alkanes were possibly derived from photosynthetic organisms changes in the source of n alkanes around 1 4 ga may suggest a decline of heterotrophic reworking to primary lipids which can be related to the formation of a quiet shallow water environment of an epicontinental sea at this stage in the yanshan basin

a statistical study on the correlation between lower ionospheric perturbations as seen by subionospheric vlf lf propagation and earthquakes 1 the subionospheric vlf lf propagation is extensively used to investigate the lower ionospheric perturbation in possible association with earthquakes an extensive period of data over 7 yr from january 2001 to december 2007 and a combination of different propagation paths in and around japan are used to examine the statistical correlation between the vlf lf propagation anomaly average nighttime amplitude dispersion and nighttime fluctuation and earthquakes with magnitude 6 0 it is then found that the propagation anomaly exceeding the 2 standard deviation criterion indicating the presence of ionospheric perturbation is significantly correlated with earthquakes with shallow depth 40 km finally the mechanism of seismoionospheric perturbations is discussed

carbon isotope chemostratigraphy of the middle riphean type section avzyan formation southern urals russia signal recovery in a fold and thrust belt abstract the avzyan formation of the southern ural mountains russia forms part of the middle riphean 1300 1000 ma type section its age is constrained to be younger than 1348 ma and older than 1080 ma and thus may preserve all or part of the mid mesoproterozoic isotopic shift this shift represents a significant reorganization of the carbon cycle and separates pre 1300 ma carbonates with 13c near 0 from post 1200 ma mesoproterozoic successions having average 13c values greater than 3 5 because the avzyan formation is a significant reference section for the mesoproterozoic and because it has the potential to record this mid mesoproterozoic shift a chemostratigraphic profile was constructed for this strongly folded and thrust faulted succession best preserved 13c values from carbonates of the avzyan formation lie mainly between 0 and 2 but the unit contains a single excursion represented by several data points to values greater than 4 the chemostratigraphy of the avzyan formation does not provide a definitive match to a better dated succession however the character of the carbon isotopic curve is most similar to that of the dismal lakes group arctic canada suggesting that the avzyan formation was deposited during the mid mesoproterozoic isotopic shift and may have an age near 1270 ma best preserved sr isotopic values of 0 70587 are also consistent with a later mesoproterozoic age

subionospheric vlf signal perturbations possibly related to earthquakes a likely vlf subionospheric signal effect related to seismic activity was first reported by hayakawa et al 1996a b in association with the great kobe earthquake we have analyzed similar data during periods around 10 other great earthquakes magnitude m 6 in order to understand the main features of such an effect the following characteristics emerged from our analysis the effect appears as a transient oscillation with a 5 to 10 day period which is initiated a few days before a large earthquake and decays over a few days to weeks after it it is mainly related to crustal earthquakes it appears when resonant atmospheric oscillations with periods in a range of 5 11 days exist before the earthquake the seismic influence on the vlf signal is probably explained by the generation of long period gravity waves during the earthquake process and their intensification at heights of 70 90 km

a systematic compilation of earthquake precursors article a survey of published scientific literature was undertaken to identify and catalog observed earthquake pre cursors the earthquake precursors selected for analysis included electric and magnetic fields gas emissions groundwater level changes temperature changes surface deformations and seismicity for each of these precursors the published scientific literature was searched to document the statistics of each reported earth quake precursor spatial extent time duration amplitude signal noise ratio to analyze dependence of the observable for each precursor on earthquake magnitude and to explore proposed physical models to explain eachearthquakeprecursor somegeneralcharacteristics wereobservedfortheseprecursoryphenomena first the largest amplitude precursory anomalies tend to occur before the largest magnitude earthquakes also the number of precursory anomalies tends to increase the closer in time to the occurrence of the earthquake finally theprecursoryanomaliestendtooccurclosetotheeventualepicenterof theearthquake ingeneral the physical models indicate that all of the precursory phenomena are related to deformation that occurs near the fault prior to the main earthquake while the models provide plausible physical explanations for the pre cursors there are many free parameters in the models that are poorly resolved

microfossil populations in the context of synsedimentary micrite deposition and acicular carbonate precipitation mesoproterozoic gaoyuzhuang formation china abstract silicified stratiform stromatolites of the mesoproterozoic gaoyuzhuang formation 1 4 1 5 ga china contain well preserved microfossils the cherts also harbor varied synsedimentary precipitates and void filling cements replaced by early diagenetic silica minerals these precipitates disclose microenvironments characterized by supersaturated solutions in protected shallow depressions within an intertidal setting the precipitates provided surfaces for selective microbial settlement and rigid sediment matrix for microbial growth together with early silicification the frequent precipitation events contributed to preservation of microfossils by reducing sediment compaction and shearing fossiliferous cherts display fine flat and wavy lamination characterized by an alternation of highly silicified thin organic rich layers with thick sediment rich layers organic rich layers are dominated either by coccoid or by filamentous microfossils whereas sediment rich layers contain abundant synsedimentary precipitates within which the microfossils are preserved in their growth position four dominant microfossils coccostratus dispergens n gen et sp eoentophysalis belcherensis eoschizothrix composita and siphonophycus inornatum occur contiguously through several tens of laminae and are identified as main frame building biological components of gaoyuzhuang stromatolites community composition microbial density distribution orientation and developmental patterns of the frame building microfossils are closely correlated with the changing depositional events of gaoyuzhuang cherts contrasting conditions of sedimentary kinetics with those of sedimentary stasis each assemblage of frame building microfossils responded to sedimentation with different mechanisms to escape burial high sedimentation rates correlate with scattered colonies of coccoids and with loose webs of predominantly upright filaments low sedimentation rates correlate with dense laterally connected colonies of coccoids and with a change in filament orientation from vertical to horizontal in multi trichomous microfossil eoschizothrix composita low sedimentation rates are also accompanied with an increase in number of trichomes per filament the observed morphological variability of the frame building microfossils is explained by microbial development reproduction and behavior by interactions between sedimentological and biological controls

seismo ionospheric signatures prior to m 6 0 taiwan earthquakes this paper examines variations of the greatest plasma frequency in the ionosphere fof2 recorded by the chung li ionosonde 25 0 n 121 1 e before m 6 0 earthquakes during 1994 1999 the 15 day running median and the associated inter quartile range are utilized as the reference and the upper or lower bounds to monitor the ionospheric fof2 variations for finding seismo ionospheric signatures precursors of the earthquakes it is found that precursors in the form of the recorded fof2 falling below its associated lower bound around 1200 1700 lt appear 1 6 days prior to these earthquakes on september 20 1999 ut september 21 taiwan local time a large mw 7 7 earthquake struck central taiwan near the small town of chi chi we analyzed the fof2 and found three clear precursors 1 3 and 4 days prior to the chi chi earthquake

sulfur isotope composition of carbonate associated sulfate from the mesoproterozoic jixian group north china implications for the marine sulfur cycle abstract the mesoproterozoic has been traditionally viewed as a period of prolonged stability in terms of environmental and biological evolution yet growing body of evidence suggests subtle yet dynamic changes in marine biogeochemical cycles in this study we present a high resolution analysis of carbonate associated sulfate cas from the mesoproterozoic jixian group 1 6 1 4 ga north china combined with previously reported carbon isotopes from the same sections sulfur isotope data provide insight into both oceanic chemistry and biospheric evolution during this period the sulfur isotopic composition of cas in the jixian group displays high amplitude variations with a total range from 3 7 to 51 9 stratigraphic variation in 34scas is most noted in the wumishan formation and records shifts of 10 over stratigraphic thickness of 100 200 m indicating a short residence time resulting from a limited oceanic sulfate reservoir differences in the pattern of isotopic variability between the gaoyuzhuang and wumishan formations suggest complex behavior of the marine sulfur cycle based on proximity of depositional environments to a local or regional chemocline and the degree of mixing between adjacent environments deposition under predominantly oxic conditions favored a stable sulfate reservoir whose isotopic composition was controlled primarily by pyrite burial by contrast depositional environments proximal to euxinic waters were subject to rapid changes in both sulfate reservoir size and isotopic composition resulting from growth and subsequent oxidation of a reactive hydrogen sulfide reservoir together these units demonstrate the difficulty of interpreting marine sulfur cycling in a low oxygen low sulfate world subject to a range of environmental controls data also reveal a long term positive trend in average 34scas and 13ccarb from approximately 10 to 20 and 0 5 to 0 5 respectively which is interpreted as reflecting prolonged organic carbon and pyrite burial burial of reduced carbon and sulfur may have resulted in a slow but steady release of oxygen to the biosphere ultimately driving a gradual increase in oceanic sulfate levels our study combined with previous contributions from the late mesoproterozoic supports hypotheses of protracted biospheric oxygenation marked by a modest increase in oceanic sulfate concentrations through the mesoproterozoic

short term earthquake prediction current status of seismo electromagnetics abstract loss of human lives as a result of earthquakes is caused overwhelmingly by the collapse of buildings within less than a few minutes of main shocks the most urgent countermeasure consists of two key elements one is strengthening of weak structures and the other is short term earthquake prediction short term prediction needs precursors although some promising precursors are reported the prevailing views in japan and elsewhere are overly pessimistic the pessimism largely roots in the fact that short term precursors are generally non seismic and tools developed for seismology are not designed to detect them nonetheless nationally funded large scale earthquake prediction programs always emphasize the need to reinforce seismometer networks they do not take into account the views of those in the science community who point to the importance of non seismic precursors while there are well founded causes to be skeptical the situation needs to be improved one reason for skepticism is that the observations of precursors have not yet been perfect enough and another is that some important fundamental aspects of non seismic precursors are still unresolved we review some of these problems

configuration of the late paleoproterozoic supercontinent columbia insights from radiating mafic dyke swarms abstract remnants of 2 1 1 8 ga orogens can be recognized in nearly every craton assembled within reconstructions of the rodinia supercontinent although no particular pattern of laterally extensive orogenic belts emerges these cratons may be the fragments of an older supercontinent formed in response to the collision and accretion of even older cratons during the early earth history paleomagnetic constraints have played a limited role in many previous reconstructions of the early precambrian supercontinent mainly because of the poor age control and a large scatter of the paleomagnetic poles the geometry of giant radiating dyke swarms and orogenic belts provide important constraints for the reconstruction of the pre rodinian supercontinent some early unmetamorphosed and undeformed mafic dyke swarms in north china southern peninsular india and north america share coeval age of 1 85 ga if these continents are assembled the overall pattern exhibited by the mafic dyke swarms appears to constitute a giant radiating swarm with a piercing point between the cuddapah rift in south india and the xiong er aulacogen in north china this suggests that the north china craton indian craton and canadian shield may be fragmented from the same landmass the reconstruction of 1 85 ga giant radiating dyke swarm attempted in this paper suggests that the north china craton india craton and canadian shield were united together to form a landmass within the columbia supercontinent before its extension and break up the 1 90 1 85 ga andean style north orogenic belt suggests that a subduction zone existed on the northern margin of the north china craton wopmay orogenic belt developed in a 1 88 1 84 ga continental volcano plutonic arc which is interpreted as the product of eastward subduction of oceanic lithosphere the transantarctica orogenic belt in east antarctica may be another candidate to be linked with the subduction zone the north orogenic wopmay orogenic and transantarctica orogenic belts could be connected to form a continuous subduction zone the orogenic comparison strengthens the configuration of the columbia supercontinent proposed by the reconstruction of the giant radiating dyke swarm the laurentia west australia and east antarctica were relatively stable from 1 85 ga to 1 20 ga as inferred from the data on dyke swarms magmatism and the paleomagnetism these continents constituted the core of the columbia supercontinent in the late paleoproterozoic time the north china craton and indian craton were however separated from the columbia supercontinent during the mesoproterozoic time

study of thermochemical sulfate reduction of different organic matter insight from systematic tsr simulation experiments abstract a series of thermochemical sulfate reduction tsr simulation experiments were carried out involving different organic matter crude oil solid bitumen type ii kerogen type iii kerogen and different sulfate species anhydrite and mgso4 to address the chemical and carbon isotopic variations of the hydrocarbon h2s and co2 the increase of main peak carbons of residual saturated hydrocarbon and the decrease of gaseous hydrocarbons from control treatment to corresponding sulfate treatments suggest that tsr promote the consumption of both liquid and gaseous hydrocarbons the 13c1 3 values generally shift positively from control treatment to sulfate treatments and the 13cethane 13cmethane values in sulfate treatments are higher than that in control treatments the variation of 13c1 3 in tsr is controlled by the isotope fractionation during the generation and consumption of c1 3 in tsr mgso4 is more reactive than anhydrite in tsr a certain amount of h2s is incorporated into solid bitumen as the result of secondary alteration we believe that the reactivity order of different organic matter in tsr is crude oil solid bitumen type ii kerogen type iii kerogen the reactivity of organic matter in tsr depends on the hydrocarbon generation kinetics of each organic matter the dissolution decomposition and precipitation of carbonate control the yield of co2 in sour reservoirs the negative shift of 13co2 with increasing tsr extent is mainly due to the inheritance effect of carbon isotope from hydrocarbons inorganic co2 sourced from the thermal decomposition or acid dissolution of carbonate mineral impose significant influence on 13co2 the h2s yields decrease with ch4 yields and increase with 13ch4 value the 13ch4 values increase with residual amount of gaseous alkane 1 h2s residual alkane h2s suggesting that methane acted as reactant in tsr the 13co2 13ch4 values decrease significantly with increasing temperature and the 13co2 is even more negative than 13ch4 in 450 c mgso4 treatments involving type ii and type kerogen accordingly methane acted as a predominant reactant in 450 c sulfate treatments in our experiment it is possible for natural gas with high gas dryness to experience methane dominated tsr in geological reservoirs

contrasting long term global and short term local redox proxies during the great ordovician biodiversification event a case study from fossil mountain utah usa abstract the great ordovician biodiversification event gobe was a time of pronounced radiation within the paleozoic and modern evolutionary faunas despite increases in metazoan diversity during both the cambrian and the ordovician recent geochemical evidence suggests that the early paleozoic may have experienced recurring deep ocean euxinia the dynamic connections between deep ocean redox and fossil rich shelf environments remain unclear but one way to elucidate these relationships is to study rocks formed during the gobe using both long term global and short term local redox proxies here we report geochemical results from the middle ordovician juab formation and kanosh formation at fossil mountain utah the kanosh formation has been interpreted by different workers either as an anoxic restricted basin or as a well oxygenated normal marine basin based on sedimentological and paleontological characteristics here we employ the sulfur isotopic composition of carbonate associated sulfate cas as a proxy for long term whole ocean redox changes during the middle ordovician we use the abundances of organic carbon and total sulfur as proxies for short term localized changes in redox during the deposition of the fossil mountain sediments organic carbon abundances are low overall average 0 7 wt maximum 1 2 wt using the most conservative estimate although some units may have had considerably higher organic content before burial total sulfur is uniformly low with an average value of 0 02 wt and a maximum value of 0 07 wt the total sulfur and organic carbon abundance results suggest that anoxia was not prevalent in the depositional environment of the juab and kanosh formations similarly the sulfur isotopic results correlate well with those reported from time equivalent strata in newfoundland suggesting that the fossil mountain sediments were not deposited in a restricted basin even though the total sulfur and organic carbon data suggest that the local environment was not anoxic our sulfur isotopic results support the hypothesis that the global ocean was likely euxinic during the middle ordovician

interpreting carbon isotope excursions carbonates and organic matter abstract variations in the carbon isotopic compositions of marine carbonate and organic carbon provide a record of changes in the fraction of organic carbon buried through time and may provide clues to changes in rates of weathering and sources of organic carbon paired carbonate and organic carbon isotope determinations provide a possibility of interpreting not only changes in the global carbon cycle through time but changes in atmospheric pco2 as well interpretations of these types of data are typically rather qualitative a quantitative basis is required to develop a better understanding of changes in the carbon cycle for this purpose we employ a simple model of the global carbon cycle which is subjected to a number of different perturbations each lasting 500 ky i e much longer than the residence times of carbon and phosphorus in the ocean atmosphere system in addition to standard considerations of carbon mass and isotopic fluxes to the ocean atmosphere system from weathering and volcanism and fluxes of organic carbon and carbonate carbon to sediments the model incorporates sensitivity of the photosynthetic carbon isotope effect to changes in pco2 the inclusion of this parameter leads to unexpected carbon isotope responses to forcing that causes increased rates of organic carbon burial a series of simple to more complex simulations illustrates the significant effects of varying differences between the carbon isotopic composition of sedimented carbonate and organic carbon b with constant b a 50 increase in organic carbon burial produces a parallel increase in carbonate and organic carbon isotopic compositions however the same simulation with b responsive to pco2 changes produces an initial parallel 13 c increase but this is followed by an even greater 13 c enrichment in organic carbon because pco2 falls in response to increased organic carbon burial the counterintuitive overall result of the enhanced organic carbon burial event is that the carbonate carbon isotopic composition actually decreases because of the more substantial increase in 13 c org in addition we illustrate the effects on carbon isotopic compositions of the oceanic inorganic carbon reservoir and buried organic matter of a 50 increase in volcanic co2 outgassing a 50 increase in weathering rate with coupled phosphate and riverine carbon flux responses a 50 decrease in shale associated organic carbon weathering a 50 decrease in silicate weathering rate and the possible effects of the rise in abundance of c4 plants in the late miocene to recent we compare the model simulated carbon isotopic responses for some of these experiments to paired carbonate and organic carbon records to illustrate how these records might be interpreted in light of the model response

investigation of ionospheric electron content variations before earthquakes in southern california 2003 2004 1 it has been proposed that earthquakes are preceded by electromagnetic signals detectable from ground and space based measurements ionospheric anomalies such as variations in the electron density a few days before earthquakes are one of the precursory signals proposed since global positioning system gps data can be used to measure the ionospheric total electron content tec the technique has received attention as a potential tool to detect ionospheric perturbations related to earthquakes here we analyze 2 years 2003 2004 of data from the southern california integrated gps network scign a dense network of 265 continuous gps stations centered on the los angeles basin for possible precursors this time period encompasses the december 2003 m6 6 san simeon and september 2004 m6 0 parkfield earthquakes we produce tec time series at all scign sites and apply three different statistical tests to detect anomalous tec signals preceding earthquakes we find anomalous tec signals but no statistically significant correlation in time or in space between these tec anomalies and the occurrence of earthquakes in southern california for the 2003 2004 period this result does not disprove the possibility of precursory phenomena but show the signal to noise ratio of a hypothetical tec precursor signature is too low to be detected by the analysis techniques employed here precursors may still be revealed for future large earthquakes in well instrumented areas such as california and japan if the tests can be developed into techniques that can better separate external influences from the actual tec signal

suspected seismo ionospheric coupling observed by satellite measurements and gps tec related to the m7 9 wenchuan earthquake of 12 may 2008 anomalous changes in the ionospheric conditions related to the wenchuan earthquake of 12 may 2008 are investigated using electron density ne from detection of electro magnetic emissions transmitted from earthquake regions demeter and champ satellites electric field from demeter and gps total electron content tec maps the normalized ne from the demeter satellite reveal that the previously reported tec increments before the earthquake can be considered as fragments of the gradual equatorial ionization anomaly eia enhancements near the epicenter longitude that began approximately 1 month before the earthquake and reached its maximum with an exceptionally large strength index 8 days prior to the main shock this feature is indirectly confirmed through the champ ne and gps tec data following the eia intensity peak disturbances in the ne and o density were observed in the nightside based on the concurrent electric field and ne changes it is suggested that eia intensification could be triggered by the e field disturbances over the epicenter