ree composition of an aqueous magmatic fluid a fluid inclusion study from the capitan pluton new mexico u s a abstract the ree content of aqueous magmatic derived fluids trapped in fluid inclusions has been determined by icp ms after crush leach extraction of the fluids in 4 samples the total ree concentration varies between 200 and 1300 ppm and is dominated by the lree especially la ce and nd fluids were released at different times from a melt which changed composition as it underwent fractional crystallisation and this is reflected in the concentration of ree in solution early formed quartz fluorite veins hosted by granophyre contain the highest concentration of ree and appear to be in equilibrium with aplite melt from which the fluid was inferred to have been derived since calculated fluid melt distribution coefficients are in broad agreement with experimentally derived values variation in the ree content of the fluids is independent of salinity which remains constant at 80 wt total salts later veins hosted by aplite contain fluid derived from a porphyritic melt and have lower ree concentrations reflecting the greater incorporation of ree into mineral phases crystallising from the melt titanite and allanite occur in these later veins ree mineral fluid distribution coefficients have been calculated for these minerals and show there is a strong preference for ree to partition into the minerals

an oscillating trend in phanerozoic non skeletal carbonate mineralogy textural and compositional data on ancient ooids and cements suggest the existence of an oscillating phanerozoic temporal trend in non skeletal carbonate mineralogy the trend shows good correlation with eustatic climatic oscillations proposed by others the most likely mechanism appears to be plate tectonically influenced oscillations in pco2 the vapour pressure of co2 rather than change in oceanic mg ca ratio

secular variation in seawater chemistry during the phanerozoic as indicated by brine inclusions in halite analysis of data on the chemical composition of primary fluid inclusions brine inclusions in primary bedded halite from many evaporite formations of northern pangea shows that during the phanerozoic the chemical composition of marine brines was oscillating significantly between the na k mg ca cl type and the na k mg cl so4 type we regard those changes as corresponding to the chemical evolution of the phanerozoic ocean the changes correlate in time with earlier suggested secular changes in the mineralogies of marine nonskeletal limestones and potash evaporites in addition to those secular changes of seawater chemistry the concentrations of k mg ca and so4 ions in marine brines underwent important changes under the influence of local factors including rock water interaction these secondary changes did not influence the principal chemical type of the brine characteristic for a given time interval in the past concentration of the ca ion did not exceed the present concentration in marine water by a

the determination of sulphate in fluid inclusions using the m o l e raman microprobe application to a keuper halite and geochemical consequences sulphate concentrations have been determined in fluid inclusions by raman spectroscopy using the m o l e microprobe after verifying that the sulphate determination is proportional to the total sulphate in the aqueous phase comparison of miso4 values in primary fluid inclusions with associated mother brine from actual solar salt works demonstrates their chemical equivalence keuper halite of marine origin has also been studied the inclusions contain solid phases anhydrite and possibly gypsum and glauberite as well the moiality of the total dissolved sulphate in the aqueous phase is lower than that obtained during present sea water evaporation at the halite stage of precipitation some geochemical hypotheses are proposed to account for this anomaly

extraordinary biomass burning episode and impact winter triggered by the younger dryas cosmic impact 12 800 years ago 2 lake marine and terrestrial sediments abstractpart 1 of this study investigated evidence of biomass burning in global ice records and here we continue to test the hypothesis that an impact event at the younger dryas boundary ydb caused an anomalously intense episode of biomass burning at 12 8 ka on a multicontinental scale north and south america europe and asia quantitative analyses of charcoal and soot records from 152 lakes marine cores and terrestrial sequences reveal a major peak in biomass burning at the younger dryas yd onset that appears to be the highest during the latest quaternary for the cretaceous tertiary boundary k pg impact event concentrations of soot were previously utilized to estimate the global amount of biomass burned and similar measurements suggest that wildfires at the yd onset rapidly consumed 10 million km2 of earth s surface or 9 of earth s biomass considerably more than for the k pg impact bayesian analyses and age regressions demonstrate that ages for ydb peaks in charcoal and soot across

was the younger dryas triggered by a flood draining of a huge lake into the northern atlantic may have triggered a cold period 12 900 years ago the route taken by the flood waters remains unknown

in situ raman spectroscopic quantification of aqueous sulfate experimental calibration and application to natural fluid inclusions abstract sulfate is an important component of geological fluids which is often encapsulated in fluid inclusions fis analyses of the composition of such fis can provide important information on the origin and properties of the fluids inside however conventional microthermometric analyses are often hampered due to the complex composition of such fluids alternatively in situ raman spectroscopy is a powerful method to determine the aqueous sulfate concentration of fis unfortunately the effect of a common component chloride on the analytical results has not been well addressed yet in addition disagreements also exist in the current spectrum processing method which also prevents the application of this method in various geological cases in this study a series of fused silica capillary capsules fsccs containing aqueous na2so4 0 01 1 5 mol kg and na2so4 nacl mna2so4 0 05 and 0 5 mol kg mnacl 0 1 4 0 mol kg solutions were prepared as standards in situ raman spectra for the stretching vibration of so42 v1 so42 the bending vibration v2 h2o and the stretching vibration vs h2o of water were collected at room temperature results show that for sulfate solutions both v2 h2o and vs h2o bands can be used as internal standards for the determination of aqueous sulfate concentration mso42 the peak area a ratios between v1 so42 and v2 h2o or vs h2o bands increased nearly linearly with mso42 in na2so4 solutions consequently the relationships between mso42 and the spectral parameters i e a v1 so42 a v2 h2o and a v1 so42 a vs h2o were established however the calculated mso42 will be underestimated when applying the above calibration curve to nacl na2so4 solutions using a v2 h2o as an internal reference in this case the influence of chloride on the calculated mso42 will be largely eliminated when using a vs h2o as an internal reference or fitting the vs h2o band with two gaussian components at 3230 cm 1 and 3450 cm 1 and then using the total peak area as internal reference it should be noted that our calibration results allow comparisons across different laboratories because the spectral intensity was corrected to reduce the response function of the spectrometer and the temperature and wavenumber dependence then the a v1 so42 a vs h2o mso42 relationship was applied to natural fis in fluorite from the dalucao hydrothermal ree deposit southwestern china and in halite from the paleogene evaporite in the jianghan basin south china the mso42 in pre ree stage fluorite hosted fis can reach 0 37 mol kg indicating that sulfate are responsible for the hydrothermal transport of ree the mso42 in the halite hosted fis were found to be in close association with the mineral assemblage serving as an indicator for the degree of evaporation or sedimentary facies

radiocarbon simulation fails to support the temporal synchroneity requirement of the younger dryas impact hypothesis fine scale temporal processes such as the synchronous deposition of organic materials can be challenging to identify using 14 c datasets while some events such as volcanic eruptions leave clear evidence for synchronous deposition synchroneity is more difficult to establish for other types of events this has been a source of controversy regarding 14 c dates associated with a hypothesized extraterrestrial impact at the younger dryas boundary ydb to address this controversy we first aggregate 14 c measurements from northern hemisphere ydb sites we also aggregate 14 c measurements associated with a known synchronous event the laacher see volcanic eruption we then use a monte carlo simulation to evaluate the magnitude of variability expected in a 14 c dataset associated with a synchronous event the simulation accounts for measurement error calibration uncertainty old wood effects and laboratory measurement biases the laacher see 14 c dataset is consistent with expectations of synchroneity generated by the simulation however the ydb 14 c dataset is inconsistent with the simulated expectations for synchroneity these results suggest that a central requirement of the younger dryas impact hypothesis synchronous global deposition of a ydb layer is extremely unlikely calling into question the younger dryas impact hypothesis more generally

hydrothermal transport and deposition of the rare earth elements by fluorine bearing aqueous liquids new technologies particularly those designed to address environmental concerns have created a great demand for the rare earth elements ree and focused considerable attention on the processes by which they are concentrated to economically exploitable levels in the earth s crust there is widespread agreement that hydrothermal fluids played an important role in the formation of the world s largest economic ree deposit i e bayan obo china until recently many researchers have assumed that hydrothermal transport of the ree in fluorine bearing ore forming systems occurs mainly due to the formation of ree fluoride complexes consequently hydrothermal models for ree concentration have commonly involved depositional mechanisms based on saturation of the fluid with ree minerals due to destabilization of ree fluoride complexes here we demonstrate that these complexes are insignificant in ree transport and that the above models are therefore flawed the strong association of h and f as hf and low solubility of ree f solids greatly limit transport of the ree as fluoride complexes however this limitation does not apply to ree chloride complexes because of this the high concentration of cl in the ore fluids and the relatively high stability of ree chloride complexes the latter can transport appreciable concentrations of ree at low ph the limitation also does not apply to sulphate complexes and in some fluids the concentration of sulphate may be sufficient to transport significant concentrations of ree as sulphate complexes particularly at weakly acidic ph this article proposes new models for hydrothermal ree deposition based on the transport of the ree as chloride and sulphate complexes

temperature dependency of long chain alkenone distributions in recent to fossil limnic sediments and in lake waters distribution patterns of c37 and c38 polyunsaturated long chain alkenones lcas serve as proxies for the determination of paleotemperatures for marine surface waters we studied recent subrecent and late glacial holocene sediments from germany austria russia and the u s to test for a correspondence between lca distribution and surface water temperature in limnic systems previously reports of lca occurrence were restricted to sediments of 6 wide distributed freshwater and alkaline lakes in this study 13 of 27 investigated lakes contained lcas in surface sediments with concentrations varying between 12 to 205 g g toc late glacial to holocene sediment sequences from lake steisslingen and lake wummsee germany lake pichozero russia and brush lake u s a contained abundant lcas with averaged concentrations of 33 to 7536 g g toc for the first time we observed the occurrence of lcas within in the water column of oligotrophic lake stechlin ne germany alkenones were restricted to the zone of maximum chlorophyll concentration within the water column indicating that lcas have a biosynthetic origin and can be attributed to phototrophic micro algae attempts to identify the producing organism however were not successful culture experiments allow various phytoplankton to be excluded as producers alkenone producing algae are evidently of small size hindering microscopical identification lcas commonly occur in high concentrations in late glacial sediments mainly during the cold period of the younger dryas whereas the holocene usually is devoid of polyunsaturated alkenones the episodic occurrence of lcas restricts their utility as proxies for continuous geological records furthermore lack of microscopical verification and the episodic distribution allow for different producers of unsaturated alkenones in recent and late glacial sediments an empirical relationship between lca distribution and temperature was observed in fossil sediments from lake steisslingen there is a good correspondence between uk37 and the temperature controlled 18o isotope ratio of lake chalk comparison of lca patterns obtained from the uppermost centimetres of lake sediments with averaged summer surface water temperatures of the lakes studied demonstrates a trend of covariance r2 uk 37 0 90 uk37 0 67 n 9 hence the same mechanism that causes temperature dependence of lca patterns in marine systems might be effective in limnic settings identification of alkenone producers and their culture under controlled temperature are still mandatory before lcas can be routinely applied as paleotemperature proxy in limnic systems

evidence for a traveling two day wave in the middle atmosphere evidence is presented for the existence of a wave number 3 westward traveling 2 day oscillation in the temperature measurements made by the nimbus 5 scr and nimbus 6 pmr instruments the wave has largest amplitude in the mesosphere at low latitudes of the summer hemisphere and has a markedly asymmetrical meridional structure it is suggested that the wave may be a free wave similar to the 5 day wave identified in nimbus 5 scr data by rodgers 1976 the vertical structure shows little phase tilt and a slight indication of an increase in amplitude with height

the deglaciation of the americas during the last glacial termination this paper reviews current understanding of deglaciation in north central and south america from the last glacial maximum to the beginning of the holocene together with paleoclimatic and paleoceanographic data we compare and contrast the pace of deglaciation and the response of glaciers to major climate events during the global last glacial maximum glgm 26 5 19 ka average temperatures decreased 4 to 8 c in the americas but precipitation varied strongly throughout this large region many glaciers in north and central america achieved their maximum extent during the glgm whereas others advanced even farther during the subsequent heinrich stadial 1 hs 1 glaciers in the andes also expanded during the glgm but that advance was not the largest except on tierra del fuego hs 1 17 5 14 6 ka was a time of general glacier thickening and advance throughout most of north and central america and in the tropical andes however glaciers in the temperate and subpolar andes thinned and retreated during this period during the bolling allerod interstadial b a 14 6 12 9 ka glaciers retreated throughout north and central america and in some cases completely disappeared many glaciers advanced during the antarctic cold reversal acr 14 6 12 9 ka in the tropical andes and patagonia there were small advances of glaciers in north america central america and in northern

abrupt climate oscillations during the last deglaciation in central north america evidence from stable isotopes and a variety of proxies from two ontario lakes demonstrate that many of the late glacial to early holocene events that are well known from the north atlantic seaboard such as the gerzensee killarney oscillation also known as the intra allerod cold period younger dryas and preboreal oscillation also occurred in central north america these results thus imply that climatic forcing acted in the same manner in both regions and that atmospheric circulation played an important role in the propagation of these events

mesospheric planetary wave signatures in the equatorial electrojet 1 using five years 1994 1998 of simultaneous and collocated measurements of horizontal winds associated with mesosphere and lower thermosphere mlt region and geomagnetic field measurements in the indian geomagnetic dip equatorial region an extensive experimental study has been made on the influences of mesospheric planetary waves on the equatorial electrojet eej the winds are measured using medium frequency mf radar 1 98 mhz located at tirunelveli the eej strength is determined by measuring the geomagnetic field strength at both the geomagnetic dip and off dip equatorial stations trivandrum and alibag india by noting the simultaneous time evolution of spectral signal morlet wavelet analysis in both the eej strength and mesospheric winds at 88 km it is found that mesospheric planetary waves with periodicities of 2 25 days often do propagate up to the ionospheric dynamo region and have their influences on eej strength sometimes only one of the parameters shows strong spectral signal in this periodicity range it is also observed that often the diurnal oscillation in eej strength and mesospheric winds exhibits coherent variations in amplitude when the signature of mesospheric planetary scale oscillations is found in the eej strength also it is found that variations in high energy solar radiations f10 7 is used as a proxy can influence the eej strength at planetary timescales this leads to an interesting question what actually causes the vertical coupling between ionosphere and atmosphere through upward propagating planetary waves to be operative only during some and not all of the episodes

application of laser raman micro analyses to earth and planetary materials abstract raman spectroscopy contributed greatly in the past 30 years or so for the advances of our understanding of earth and planetary materials and their associated geological processes after a brief introduction of the history and basic theory of raman spectroscopy the advantages and disadvantages of this spectroscopic analysis method were listed and examples were given when appropriate for its applications to the analyses of earth materials which include minerals and organic materials silicate glasses and melts aqueous solutions and gases and h2o gas systems previous works were discussed and cited this was followed by a review on applications of raman spectroscopic studies of minerals and fluids to petrogenesis and crustal evolution in which several p t diagrams were given to show metamorphic evolution of ultra high pressure units as well as a schematic cross section of the earth s outer shells showing recycling of crustal materials in different tectonic regimes for its applications to the analyses of planetary materials which include lunar samples martian meteorites and other extraterrestrial materials a brief history on the starting and development of raman spectroscopy technique was given we then discussed raman point counting and quantitative chemical analysis methods developed for obtaining quantitative information on mineral proportions and mineral chemistry in planetary surface explorations respectively finally new developments and future works which include quantitative analyses raman mapping portable raman systems and raman effects resonance raman spectroscopy cars sers and their associated applications were discussed

the major composition of a middle late eocene salt lake in the yunying depression of jianghan basin of middle china based on analyses of fluid inclusions in halite abstract during the cretaceous tertiary transition in eastern china abundant halites formed in non marine areas many continental salt deposits from inland salt lakes were formed in eastern china in faulted basins as a result of the northward movement and collision of the indo china plate with the eurasian plate including the bohai gulf basin however a marine transgression versus a non marine origin of these evaporites remains to be determined primary fluid inclusions trapped in halite deposits can directly record the composition of evaporated seawater or salt lake water such as those in the cretaceous halite in the khorat plateau laos and thailand area can resolve the origins of the evaporate deposits recent fluid inclusions data in the khorat plateau coincide with the predicted secular variation of seawater and are comparable to other fluid inclusions in cretaceous marine halite indicating these fluid inclusions are directly related to a marine transgression our analyses in this study shows that the average k mg2 and so 4 2 contents are 8 8 5 0 and 6 8 g l respectively in the primary fluid inclusions in halite of middle late eocene from the yunying depression of china these numbers are much less than those in the contemporary spanish primary fluid inclusions in halite precipitated from seawater 16 4 36 3 and 12 5 g l for k mg2 and so 4 2 respectively furthermore br contents of all fluid inclusion samples in halite from the yunying depression are lower than 2 ppm vs 55 58 ppm at the base of spanish contemporary marine halite and their 37cl values range from 0 11 to 2 94 vs 0 09 to 0 24 in sylvite of spanish deposit indicating that the compositions of the middle late eocene brines trapped in halite in the yunying depression of china are very different from those derived from the contemporary seawater and are considered to be resulted from evaporation of an inland saline lake water with little influence of seawater

methane and the origin of five element veins mineralogy age fluid inclusion chemistry and ore forming processes in the odenwald sw germany abstract five element veins ag bi co ni as have been valuable mineral deposits since medieval times the characteristic occurrence of large aggregates of native metals up to several dm surrounded by a succession of arsenides makes this vein type attractive for mining industry natural history museums and private mineral collectors nevertheless the exact formation process of these specific vein types has not been fully understood this is the first case study applying a new model which includes methane as a reducing agent to two typical examples of such mineralisations from the odenwald sw germany we analysed all mineralogical varieties ag as and bi dominated of the five element veins in the odenwald sw germany in terms of ore textures mineral chemistry fluid inclusion compositions microthermometry and raman spectroscopy stable isotopes c o and s and in situ u pb age dating of calcite and prehnite a variety of ag bi and as dominated native metal arsenide calcite veins sulphide calcite veins and arsenide free ag hg barite veins occurs in the odenwald and has been examined in this study all arsenide veins have in common that up to dm sized often dendritic native metals are overgrown by a succession of arsenides followed by carbonate and finally sulphides the succession of arsenides shows a distinct spatial and temporal chemical trend in their composition this trend evolves from ni to co and finally fe dominated compositions from the core to the rim in contrast spatially closely related ag hg barite veins consist of almost mono mineralic amalgam inter grown with barite in situ u pb age dating of low u calcite and prehnite was applied to constrain the age of hydrothermal mineralisation the results imply that the five element veins formed at 170 180 ma from na ca cl fluids at 290 c salinities of 27 wt and ca ca na of 0 30 to 0 35 in the presence of methane the age data clearly relate the relevant fluid migration to extension and crustal thinning caused by the opening of the north atlantic ternary mixing of a deep seated metal rich basement brine fluid a a sulphide bearing h2s and hs basinal sedimentary brine fluid b and methane dominated fluid gas fluid c induce ore formation mixing of such chemically contrasting fluids results in a strong chemical disequilibrium of the mixed fluid which potentially leads to rapid precipitation of native metals and arsenides with these specific ore textures in contrast sulphide bearing calcite veins formed under similar p t conditions due to mixing of fluid a and b while fluid c was absent additionally u pb analyses of post ore calcite yields ages of 60 ma which indicates that a second calcite formation event is associated with the onset of the upper rhine graben rifting veins with amalgam and barite form as a consequence of post ore oxidation of ag2s at 135 c conspicuously this secondary silver ii has hg contents of up to 30 wt in contrast to hg contents below 1 wt of primary silver i and ag2s the formation of amalgam was most likely related to decrease of the s2 so42 ratio due to cooling of the late hydrothermal fluid resulting in the destabilisation of hg bisulphide complexes in this fluid

raman microspectrometry of fluid inclusions abstract for many kinds of fluid inclusions the coupling of microthermometry and raman microspectrometry is still the only viable option to obtain compositions of single fluid inclusions a review is given on the basis of 16 years of experience and helped with about 120 references of the instrumentation analytical conditions and methodology of the application of raman microspectrometry to gaseous aqueous and hydrocarbon inclusions and their daughter minerals

the quasi two day wave observed in the equatorial middle atmosphere an oscillation with a period near 2 days is found in radar wind measurements made in the upper mesosphere and lower thermosphere at christmas island 2 n 157 w in the central pacific the oscillation is particularly strong in the meridional wind component and seems to be present almost continuously ir the 80 100 km height region although some intermittency is evident wave amplitudes are especially large about one month after the solstices in july august and in january february at times coincident with large 2 day wave events in the summer mesosphere at extratropical latitudes power spectral and complex demodulation techniques are used to study the amplitude and frequency variations of the oscillation as a function of height and time downward phase propagation is found consistent with upward energy propagation and with a vertical wavelength of about 70 km an unusual feature is a shift in wave period from near 50 hours in july august to 48 hours in january february when the largest amplitudes up to 45 m s 1 are observed a 16 hour oscillation is also found at times when the 2 day wave amplitudes are largest the observations are consistent with the 2 day wave being a manifestation of the 3 0 rossby gravity normal mode another weaker oscillation is also found in the meridional wind field at a period near 44 hours this oscillation may be due to the 2 0 normal mode

hydrothermal transport deposition and fractionation of the ree experimental data and thermodynamic calculations abstract for many years our understanding of the behavior of the ree in hydrothermal systems was based on semi empirical estimates involving extrapolation of thermodynamic data obtained at 25 c haas et al 1995 wood 1990a since then a substantial body of experimental data has accumulated on the stability of aqueous complexes of the ree these data have shown that some of the predictions of haas et al 1995 are accurate but others may be in error by several orders of magnitude however application of the data in modeling hydrothermal transport and deposition of the ree has been severely hampered by the lack of data on the thermodynamic properties of even the most common ree minerals the discrepancies between the predictions of haas et al 1995 and experimental determinations of the thermodynamic properties of aqueous ree species together with the paucity of data on the stability of ree minerals raise serious questions about the reliability of some models that have been proposed for the hydrothermal mobility of these critical metals in this contribution we review a body of high temperature experimental data collected over the past 15 years on the stability of ree aqueous species and minerals using this new thermodynamic dataset we re evaluate the mechanisms responsible for hydrothermal transport and deposition of the ree we also discuss the mechanisms that can result in ree fractionation during their hydrothermal transport and deposition our calculations suggest that in hydrothermal solutions the main ree transporting ligands are chloride and sulfate whereas fluoride carbonate and phosphate likely play an important role as depositional ligands in addition to crystallographic fractionation which is based on the differing affinity of mineral structures for the ree our models suggest that the ree can be fractionated hydrothermally due to the differences in the stability of the lree and hree as aqueous chloride complexes

evaluating seawater chemistry from fluid inclusions in halite examples from modern marine and nonmarine environments fluid inclusions from marine halites have long been studied to determine the chemical composition of ancient seawater chemical analyses of the major ions in fluid inclusions in halites from the solar saltwork of great inagua island bahamas and from the supratidal sabkha baja california mexico show that modern marine halites faithfully record the chemical signature of seawater the major ions in great inagua and baja california fluid inclusions display distinctive linear trends when plotted against one another ie na k and so42 vs mg2 and cl which track the evaporation path of seawater as it evolved during the crystallization of halite these evaporation paths defined for the major ions by fluid inclusions in halite overlap findings of computer simulations of the evaporation of modern seawater by the harvie moller and weare hmw computer program the close match between the hmw seawater evaporation paths and the great inagua fluid inclusion data is not surprising considering the carefully controlled inflow evaporation and discharge of seawater at the great inagua saltwork the major ion chemistry of fluid inclusions from the baja california halites matches the hmw seawater evaporation paths in most respects but one baja fluid inclusion has lower concentrations of mg2 than evaporated seawater nonmarine inflows and syndepositional recycling of preexisting salts in the baja california supratidal setting were not large enough to override the chemical signature of evaporating seawater as the primary control on the baja fluid inclusion compositions fluid inclusions in halites from the nonmarine qaidam basin qinghai province western china have a distinctly different major ion chemical signature than does global seawater the fluid inclusion chemistries from the qaidam basin halites do not lie on the evaporation pathways defined by modern seawater and can clearly be differentiated from fluid inclusions containing evaporated seawater if fluid inclusions in halites from modern natural settings contain unmistakable samples of evaporated seawater then evaluation of the chemistry of ancient seawater by chemical analysis of fluid inclusions in ancient marine halites by means of the same approach should be valid

delayed hydrological response to greenland cooling at the onset of the younger dryas in western europe during the younger dryas cold event about 12 800 years ago environmental change in western europe seems to occur 170 years after cooling over greenland lake sediment analyses confirm this delay and suggest european hydrological and vegetation change occurred only after the build up of sea ice in the north atlantic pushed the westerly wind system south

late and post glacial evolution of lake steisslingen i abstract piston cores from lake steisslingen a small hard water lake situated 20 km west of lake constance and mainly supplied by submerged springs reveal a record of the environmental history going back to 15 600 cal yr bp from the bolling to ca 9800 cal yr bp the sediments are partly seasonally laminated from then on up to the middle ages the lamination is mostly undisturbed providing a high resolution time scale by varve counting a detailed pollen profile and 13 ams 14c analyses all investigated sediment sections show evidence of exceptionally high sulphate concentrations in the lake water which lead to the fixation of all reactive iron as pyrite the high sulphur content can only be attributed to s rich water supplied by the submerged springs thus indicating the miocene obere meeres molasse as the dominant aquifer since soil erosion is strongly reduced due to increased forest density in the preboreal boreal the submerged springs are the main nutrient source for the lake mixing or stable stratification of the waterbody mostly depends on nutrient availability and bioproductivity in the epilimnion the controlling external factors are wind and changes in water level and or temperature at the end of the younger dryas and during the preboreal low water levels and precipitation rates are assumed the water column mixing was regular bioproductivity high and high degradation activity of organic matter led to a redissolution of calcite the hydrological separation of a northern shallow lake seeried probably fell into the period of this low lake level around 10 450 10 300 cal yr bp the lake level rose but never again reached the former level between 10 000 and 7200 cal yr bp non glacial varves are even found in shallower parts of the lake indicating a stable anoxic monimolimnion with a rising chemocline bioproductivity was low wind protection provided by the now dense forestation and favourable climatic conditions e g high summer temperatures and low winter temperatures seem to be the responsible factors fluctuating human impact is identified from about 7400 cal yr bp until permanent settlement by the alemanni about 1500 cal yr bp strong human influence is observed from 2000 cal yr bp onwards when agricultural activity and clearing of the shoreline vegetation by man caused high soil erosion rates and thus eutrophication at about 800 cal yr bp the recent hydrological conditions were established by implementing an artificial drain thus lowering the lake level

thermochemical sulphate reduction in the upper devonian cairn formation of the fairholme carbonate complex south west alberta canadian rockies evidence from fluid inclusions and isotopic data the fairholme carbonate complex is part of the extensively dolomitized upper devonian carbonate reefs in west central alberta the studied formations contain moulds up to 10 cm in diameter which are filled partially with saddle dolomite quartz and calcite cements these cements precipitated from a mixture of brines that acquired high salinity by dissolution of halite and brines derived from evaporated sea water the fluids were warm homogenization temperature of primary fluid inclusions of 76 to 200 c and saline 20 to 25 wt nacl equivalent and testify to thermochemical sulphate reduction processes the latter is deduced from s in solid inclusions co2 and h2s in volatile rich aqueous inclusions and depleted d 13 c values down to 26 vienna pee dee belemnite high 87 sr 86 sr values 0ae7094 to 0ae7110 of the cements also indicate interaction of the fluids with siliciclastic sequences the thermochemical sulphate reduction related cements probably formed during early laramide burial another younger calcite phase characterized by depleted d 18 o values 23ae9 to 13ae9 vienna pee dee belemnite low na 27 to 37 p p m and sr 39 to 150 p p m concentrations and non saline 0 wt nacl equivalent fluid inclusions is attributed to post laramide meteoric water

some seasonal hemispheric similarities in ƒ o f2 quasi 2 day oscillations the annual variations of the amplitude period and probability of existence of of2 quasi 2 day oscillations at middle latitudes in both northern and southern hemispheres are investigated the of2 hourly data for the period 1977 1982 for stations kiev 50 5 n 30 5 e and wakkanai 45 39 n 141 69 e for the northern hemisphere and kerguelen 49 35 s 70 24 e and campbell island 52 6 s 169 1 e for the southern hemisphere are used for analysis it is found that there is a strong tendency for hemispheric similarities in the seasonal variations of oscillation amplitude period and probability of existence the annual variations of the oscillation amplitude are modulated by the 12 month hemispheric and semiannual geomagnetic waves the dominant period of oscillation is maximum in summer 50 51 hours and minimum in winter 47 49 hours and the probability of existence has a maximum in the summer half year and minimum in the winter half year the seasonal similarities in the annual variations of the oscillation period and the probability of existence show the possible influence of the planetary 2 day wave in the middle neutral atmosphere on the electron density variations in the f region

a multiphasic younger dryas cold period recorded in sediments of lake steisslingen sw germany a biomarker perspective abstract the younger dryas 12 680 11 590 yr bp was the last millennial scale cold event of the quaternary when a mean annual temperature decline of 3 5 c impacted severely on the environment whereas pollen distributions document changes in land vegetation details of limnic ecosystem responses to the cooling event and to its recovery are still not well known here we studied the laminated sediments of lake steisslingen sw germany deposited between 13 500 and 11 100 yr bp in order to investigate the evolution of an aquatic ecosystem bulk sediment and organic matter composition mark onset and termination of the younger dryas but remain monotonous through this interval requiring application of organic and isotope geochemical techniques to follow past ecosystem dynamics the younger dryas is characterized by both an abrupt appearance and demise of long chain alkenones indicative for haptophyte algae based on algal and bacterial biomarker distribution the younger dryas can be divided into three stages each characterized by the dominance of a microorganism group the first phase was dominated by nc17 alkanes and hopanoids indicative of cyanophytes and heterotrophic bacteria the second phase shows a proliferation of cold adapted haptophyte algae while in the latest phase highly branched isoprenoids hbi reveal an aquatic community shift towards diatoms heterocyte glycolipids document a moderate change in n2 fixing cyanobacterial community structure over the allerod younger dryas transition but show a marked collapse of the cyanobacteria association at the younger dryas preboreal climate recovery terrigenic wax lipids indicate significant changes in vegetation between the allerod younger dryas and preboreal chronozones but remain homogeneous within the younger dryas

support for two subglacial impact craters in northwest greenland from earth gravity model eigen 6c4 and other data abstract we support the very recent discovery of two impact craters under the ice of northwest greenland hiawatha glacier and paterson these discoveries are based mainly on geology and bedrock topography we added an analysis of gravity field aspects descriptors in addition to the traditional gravity and magnetic anomalies the gravity aspects the marussi tensor of the second derivatives the gravity invariants and their special ratio strike angles and virtual deformations provide more complex and comprehensive information about the underground density variations due to a causative body than ordinary gravity anomalies they show signals typical for the individual geological features like a mountain volcano fault river valley paleo lake ground water hydrocarbon mineral deposits etc as well as for the targets known as impact craters our method has been tested on various geological features on the earth and the moon the gravity aspects are in our case derived from the recent global static combined earth gravity field model eigen 6c4 with a ground resolution 9 km and a precision 10 mgal a further data come from the digital magnetic field database emag 2 with resolution 5 km our method is novel and independent of anything which led to discoveries of these craters in greenland

a multiproxy study of younger dryas and early holocene climatic conditions from the grabia river paleo oxbow lake central poland abstract a multi proxy reconstruction of water depth temperature and precipitation inferred from cladocera chironomidae and pollen assemblages has been obtained from wierczyna paleo oxbow central poland during the younger dryas yd and early holocene results suggest that the yd was relatively cold and comprised two main phases the first ca 12 500 12 000 cal yrs bp is characterized by a continental climatic regime and a decrease in winter temperatures and precipitation but an increase in spring summer precipitation the second phase ca 12 000 11 500 cal yrs bp was more mild with a variable continental climate an increase in summer and winter temperature a lengthening of the growing season and increased annual precipitation the reconstructed water level generally follows changes in spring and summer precipitation and length of growing season the frequency and timing of hydroclimatic oscillations at wierczyna show strong similarities to records from other sites in europe this confirms that oxbows and valley mire ecosystems respond to rapid climate change during the yd and early holocene this study therefore brings new insights into the effects of climate changes on river environments especially during the yd we also discuss the limitations of water depth temperature and precipitation reconstructions inferred from the studied biotic assemblages

upper crustal fluid migration an example from the variscides of sw ireland the density and composition of single generation fluids in quartz veins from two similar host lithologies located either side of the irish variscan front were investigated using fluid inclusion microthermometry and crush leach analysis the front marks the northern boundary of a distinctive cleavage developed under sub greenschist facies conditions and coincides with the margin of a fault controlled inverted half graben the late devonian munster basin trapped fluids in variscan veins north of this basin have medium salinities 4 14 wt nacl eq and densities generally compatible with the expected p t conditions of deformation in the area fluids in veins south of the half graben margin can be grouped into those in a syn compressional veins with moderate salinities 8 16 wt and b late stage veins associated with post orogenic extension which have trapped high salinity fluids 22 27 wt fluid densities for both vein types are broadly compatible with estimated p t conditions of both trapping events crush leach analyses reveal that all the fluids analysed have br cl ratios close to smow variations in i cl ratios and cation chemistry indicate significant water rock interaction for medium salinity fluids on either side of the front the marked internal consistency in br cl ratios from northern and southern fluids coupled with the broad ranges of cation to chloride ratios suggests that an early homogenous marine brine was subsequently modified by differing migration histories during the late palaeozoic tectono sedimentary evolution of the area it is contended that on a megascopic scale gravity driven fluid flow controlled by megascopic fold geometries was the dominant mechanism of fluid migration associated with the buckling phase of the orogen while expulsion of supra hydrostatically pressurised fluids is associated with late stage orogenic extension

sulfate brines in fluid inclusions of hydrothermal veins compositional determinations in the system h2o na ca cl so4 sulfate is among the most abundant ions in seawater and sulfate bearing brines are common in sedimentary basins among other environments however the properties of sulfate bearing fluid inclusions during microthermometry are as yet poorly constrained restricting the interpretation of fluid inclusion compositions where sulfate is a major ion the schwarzwald mining district on the eastern shoulder of the upper rhinegraben rift is an example of a geologic system characterized by sulfate bearing brines and constraints on the anion abundances chloride versus sulfate would be desirable as a potential means to differentiate fluid sources in hydrothermal veins in these regions here we use the pitzer type formalism to calculate equilibrium conditions along the vapor saturated liquidus of the system h2o na ca cl so4 and construct phase diagrams displaying the predicted phase equilibria we combine these predicted phase relations with microthermometric and crush leach analyses of fluid inclusions from veins in the schwarzwald and upper rhinegraben to estimate the compositions of these brines in terms of bulk salinity as well as cation and anion loads sodium versus calcium and chloride versus sulfate these data indicate systematic differences in fluid compositions recorded by fluid inclusions and demonstrate the application of detailed low temperature microthermometry to determine compositions of sulfate bearing brines thus these data provide new constraints on fluid sources and paleo hydrology of these classic basin hosted ore forming systems moreover the phase diagrams presented herein can be applied directly to compositional determinations in other systems