hypersaline burial diagenesis delineated by component isotopic analysis late paleozoic limestones west texas abstract pennsylvanian to lower permian cyclic platform carbonates from the southwest andrews area of west texas are now 3 km below the land surface isolated samples of brachiopod shell zones of calcite cement and saddle dolomite from limestone cores of the southwest andrews oilfields have been analyzed isotopically to determine if 1 diagenesis is dominated by early meteoric processes as suggested by bulk rock isotopes 2 whether significant burial diagenesis occurred in hypersaline waters and 3 whether most burial cements are allochthonous or internally derived bulk isotopic analyses of limestones show systematic variation in 13c and 18o according to length of subaerial exposure and stratigraphic position chemically zoned calcite cements show four growth stages stage 1 and 2 cements have average 13c values of 4 6o oo and average 18o of 5 0o oo and most are interpreted to have precipitated during subaerial exposure in meteoric water a few stage 1 cements with average 13c values of 4 7o oo and 18o of 1 4o oo apparently precipitated below the sediment surface from modified seawater in a sulfate reduction zone stage 3 and 4 calcite cements precipitated after compaction and compose up to 25 of the total rock volume they have 13c values 0 2o oo to 4 4o oo that vary according to stratigraphic position and are similar to bulk rock samples of the host limestone the 13c values indicate local derivation by dissolution of adjacent rock the 18o values of stage 3 and 4 cement 5 5o oo to 3 5o oo are indistinguishable from stages 1 and 2 cements precipitated from meteoric water the decrease in 18o expected from elevated temperatures during burial present formation temperature of 55 c is negated by precipitation from a late permian brine with 18o values of 5o oo stages 3 and 4 calcite and saddle dolomite cements have 87sr 86sr values that are lower than 87sr 86sr values for contemporaneous marine carbonate 0 70830 this is probably due to incorporation of sr with low 87sr 86sr values 0 70672 to 0 70682 also from the late permian hypersaline brine the southwest andrews area has several diagenetic features that are probably more common in ancient limestone than previously recognized 1 burial cements have 18o values similar to meteoric cements when precipitated from hypersaline waters with 18o values 5o oo greater than contemporary seawater 2 deep burial cements have 13c values similar to the bulk rock because carbon is derived from pressure dissolution of nearby carbonate 3 bulk rock isotope values are characteristic of marine limestones subjected to meteoric diagenesis even though they have suffered substantial deep burial diagenesis this study clearly illustrates the value of analyzing diagenetic components to accurately understand porosity evolution in limestones

origins of the reversed flow over the windward alpine foothills during map iop3 and iop8 the synoptic scale situations during the two intensive observing periods iops of the mesoscale alpine programme map characterized by persisting precipitation and down valley flow as observed by the doppler on the wheel radar dow over the two alpine valleys toce and ticino were investigated the first period iop3 24 27 september 1999 was characterized by a south westerly flow and convective precipitation whereas the second period iop8 20 21 october 1999 by a down valley flow and stratiform precipitation during iop3 the down valley northerly flow over the north western part of the po valley was confined within a thin layer of 200 300 m depth during iop8 the northerly flow extended from the alps foothills to the ligurian sea in a deep layer of 1 2 km height the meso nh numerical model with a 2 5 km horizontal mesh grid reproduced the characteristics of both cases from the valley scale to the meso scale sensitivity experiments were furthermore performed in order to highlight the relationships between wet or dry drainage flow channelled by the alpine orography mesoscale upstream flow blocked by the alps and a regional cold pool at the foothills inside the po valley during iop8 the diabatic processes were dominant at local scales in confirmation of steiner results based on the dow observations and they were significant at regional scales upstream of the alps by maintaining a cold pool over the po valley the iop3 low level flow reversal occurred as the flow began to cross over the alps instead of turning around a downslope flow is associated with the blocked regime period upstream of the alps copyright 2006 royal meteorological society

is mid late paleozoic ocean water chemistry coupled with epeiric seawater isotope records isotopes of epeiric sea carbonates are used to construct seawater records for modeling global changes in paleozoic ocean chemistry climate and for intercontinental correlation we present for the first time geochemical results of paleozoic brachiopods biogenic low mg calcite blmc from open ocean permian carboniferous seamounts of japan situated in the tropical mid panthalassic ocean strontium isotope values of blmc from the panthalassic and paleotethys oceans are coupled with those of coeval specimens from epeiric seas of north america europe and russia p 0 393 but not with those of epeiric sea whole rocks matrix aragonite calcite mac p 0 029 and conodonts biogenic apatite ba p 0 031 oxygen isotope values of blmc from the panthalassic and paleotethys exhibit mixed results with studies of counterparts from epeiric seas p 0 596 reflecting overprinting of local environmental conditions on global trends carbon isotope values of blmc and mac from the panthalassic and paleotethys oceans are generally dissimilar to those of coeval material from epeiric seas of north america europe and russia p 0 001 and 0 002 respectively factors such as water mass stratification evaporation dilution depth temperature carbon burial and or oxidation variations and syndepositional diagenesis within the local environment probably influenced the chemistry of the fauna and accumulating sediments this decoupling of carbon and oxygen isotope values from the open ocean with those from epeiric seas makes questionable the use of isotope results from epeiric seas for international correlation constructing global seawater records determining fluxes in the global carbon cycle and for modeling climate changes and subsequently atmospheric carbon dioxide levels

characterisation and origin of new zealand nephrite jade using its strontium isotopic signature abstract nephrite jade occurs in three terranes dun mountain maitai caples and torlesse in new zealand where it is associated with ultramafic and ophiolitic rocks in narrow metasomatic reaction zones at the margins of serpentinite having harzburgite gabbro dolerite precursors with silicic metasediments and metavolcanics true nephrite fabrics are developed only locally where marginal shearing is intense and late in the metamorphic history 87 sr 86 sr values of these nephrites do not display the primitive values of their gabbro dolerite precursor component i e 0 7030 0 7035 as expected if formed during serpentinisation rather the nephrites have more evolved 87 sr 86 sr values inherited from the metasediment component at a later stage and which fall within particular terrane groups dun mountain maitai 0 7045 0 7060 caples 0 7058 0 7075 and torlesse 0 7085 0 7110 rb sr ages and initial 87 sr 86 sr ratios of the metasediment component from in situ nephrite localities when compared with their counterparts throughout the host terrane show that nephrite sr isotopic compositions are characteristic of the host terrane

strontium isotope quantification of siderite brine and acid mine drainage contributions to abandoned gas well discharges in the appalachian plateau unplugged abandoned oil and gas wells in the appalachian region can serve as conduits for the movement of waters impacted by fossil fuel extraction strontium isotope and geochemical analysis indicate that artesian discharges of water with high total dissolved solids tds from a series of gas wells in western pennsylvania result from the infiltration of acidic low fe fe 10 mg l coal mine drainage amd into shallow siderite iron carbonate cemented sandstone aquifers the acidity from the amd promotes dissolution of the carbonate and metal and sulfate contaminated waters rise to the surface through compromised abandoned gas well casings strontium isotope mixing models suggest that neither upward migration of oil and gas brines from devonian reservoirs associated with the wells nor dissolution of abundant nodular siderite present in the mine spoil through which recharge water percolates contribute significantly to the artesian gas well discharges natural sr isotope composition can be a sensitive tool in the characterization of complex groundwater interactions and can be used to distinguish between inputs from deep and shallow contamination sources as well as between groundwater and mineralogically similar but stratigraphically distinct rock units this is of particular relevance to regions such as the appalachian basin where a legacy of coal oil and gas exploration is coupled with ongoing and future natural gas drilling into deep reservoirs

parent brine of the castile evaporites upper permian texas and new mexico abstract the upper permian lower ochoan castile formation is a major evaporite sequence 10 000 km3 of calcite anhydrite and halite in west texas and southeastern new mexico traditionally the castile brine has been considered to have been derived from seawater this tradition has recently been challenged by two versions of the closed basin drawdown model they call for deposition from a mixed brine in part marine and in large part nonmarine they propose drawdown of as much as 500 m to form a major sink for ground water issuing from the surrounding capitan reef complex a large fraction of the solute in the brine body is inferred to have been recycled from older permian evaporites on the surrounding shelf strontium isotope analyses show no evidence that meteoric ground water was contributed to the castile brine from a stratigraphic geographic and lithologic array of 65 samples of anhydrite gypsum and calcite 59 have an 87sr 86sr ratio of 0 706923 sw of 225 0 a ratio that is the same as that of strontium in early ochoan ocean water if considerable 15 influx of meteoric water had occurred enough continental strontium would have been introduced to have resulted in higher ratios low bromide values 20 40 ppm in castile halite which have been used to argue for meteoric influx and for recycled salt probably resulted from diagenesis during shallow burial by halite centimeter size bottom grown crystals of gypsum were altered to nodular anhydrite the rising water of dehydration caused the halite to recrystallize during the recrystallization some bromide was expelled despite the large volume of water that evaporated annually from its surface 52 km3 yr assuming an evaporation rate of 2 m yr the castile brine body never completely desiccated the surrounding shelf was flat hot and generally dry it probably could not have supplied a significant volume of meteoric spring water to the basin over tens of thousands of years more likely during the entire history of the evaporite sequence influx was dominantly marine marine ground water flowed through the capitan formation into the evaporite basin along its southern and possibly western margin probably with a rate of flow that was usually fast enough to prevent major drawdown of the brine surface

mineralogy geochemistry and petrogenesis of green nephrite from dahua guangxi southern china abstract a new nephrite deposit with potential for economic exploitation was recently discovered in dahua county hechi city guangxi autonomous region china previous studies have focused primarily on white black and black cyan nephrite from dahua whereas few studies have been carried out on green nephrite in this study the mineralogical petrological and geochemical characteristics of nephrite from this new deposit were systematically studied using polarized light microscopy scanning electron microscopy electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry and the deposit genesis was discussed the results show that dahua green nephrite consists of interwoven microfibers and the main mineral component is tremolite the mg2 mg2 fe2 ratio ranges from 0 951 to 1 00 andthe subordinate minerals include diopside chlorite calcite quartz apatite albite titanite and andradite the contents of trace elements cr ni and co are much lower than in metasomatized serpentinite type nephrite the rare earth element content is generally high 62 011 223 116 ppm with a positive eu anomaly 1 009 2 343 positive and negative ce anomalies 0 913 1 078 enrichment in light rare earth elements and flatness in heavy rare earth elements the distribution curves of the rare earth elements differ between the nephrite and the surrounding rock samples indicating multiple sources and a multiperiod superposition of the ore forming fluids the fe2 mg2 fe2 ratio in dahua green nephrite is lower than 0 06 indicating that the nephrite deposit is surrounded by carbonates by taking c ca2 c mg2 and c fe2 fe3 as endmembers for projection amphibole can be concluded to have originated from contact metasomatism considering the findings of the geological survey the dahua green nephrite likely belongs to the magmatic hydrothermal metasomatic type and its ore deposit is related to basic intrusive rocks such as diabase and hydrothermal fluid carried by magma contact metasomatism and hydrothermal metamorphism occurred with dolomitic limestone and other carbonate rocks under certain temperature and pressure conditions during the variscan indosinian period this systematic study of the newly discovered dahua green nephrite deposit provides a theoretical basis for the prospecting of nephrite deposits in the study area

is global warming affecting cave temperatures experimental and model data from a paradigmatic case study this research focuses on the mechanisms that transfer the variations in surface atmospheric temperature into caves to evaluate whether they record the warming trend of recent decades as a study case we use the data from a hall in postojna cave slovenia which was monitored from 2009 to 2013 the low frequency thermal variability of this cave chamber is dominated by the conduction of heat from the surface through the bedrock we implemented a thermal conduction model that reproduces low frequency thermal gradients similar to those measured in the cave at the 37 m depth of this chamber the model confirms that the bedrock is already recording the local expression of global warming with a delay of 20 25 years and predicts a cave warming during the coming decades with a mean rate of 0 015 0 004 c year 1 however because of the transfer of surface atmosphere thermal variability depends on the duration of the oscillations the thermal anomalies with periods 7 15 years in duration have delay times 10 years at the studied hall the inter annual variability of the surface atmospheric temperature is recorded in this cave hall although due to the different delay and amplitude attenuation that depends on the duration of the anomalies the cave temperature signal differs significantly from that at the surface as the depth of the cave is a major factor in thermal conduction this is a principal control on whether or not a cave has already recorded the onset of global warming

seawater 87sr86sr for the late permian delaware basin evaporites new mexico u s a abstract the delaware basin southeastern new mexico u s a contains a thick section of marine evaporites the three uppermost units all of ochoan age of evaporites are in ascending order castile formation salado formation and rustler formation the castile consists predominantly of bedded and massive anhydrites the salado of massive halite with numerous interbeds of anhydrite sylvite and minor other units and the rustler of impure anhydrites gypsums halites silty and clayey units dolomites and others the previously established seawater 87 sr 86 sr curve for the late latest permian is marked by a dramatic increase from 0 7068 at 250 ma ago to 0 7072 by the permian triassic boundary data are not shown for rocks of approximate ochoan age however the results of our study show the following average 87 sr 86 sr values for the rocks samples castile 0 706880 0 000005 salado 0 70688 0 000004 and rustler 0 706976 0 000008 thus a systematic increase in 87 sr 86 sr is observed from castile to salado and especially to rustler consistent with a previous prediction these data are submitted for the seawater curve for the ochoan group upper evaporites of late permian age

analytical solution and computer program fast to estimate fluid fluxes from subsurface temperature profiles this study details the derivation and application of a new analytical solution to the one dimensional transient conduction advection equation that is applied to trace vertical subsurface fluid fluxes the solution employs a flexible initial condition that allows for nonlinear temperature depth profiles providing a key improvement over most previous solutions the boundary condition is composed of any number of superimposed step changes in surface temperature and thus it accommodates intermittent warming and cooling periods due to long term changes in climate or land cover the solution is verified using an established numerical model of coupled groundwater flow and heat transport a new computer program fast flexible analytical solution using temperature is also presented to facilitate the inversion of this analytical solution to estimate vertical groundwater flow the program requires surface temperature history which can be estimated from historic climate data subsurface thermal properties a present day temperature depth profile and reasonable initial conditions fast is written in the python computing language and can be run using a free graphical user interface herein we demonstrate the utility of the analytical solution and fast using measured subsurface temperature and climate data from the sendia plain japan results from these illustrative examples highlight the influence of the chosen initial and boundary conditions on estimated vertical flow rates

borehole climate reconstructions spatial structure and hemispheric averages 1 ground surface temperature gst reconstructions determined from temperature profiles measured in terrestrial boreholes when averaged over the northern hemisphere estimate a surface warming of 1 k during the interval ad 1500 2000 other traditional proxy based estimates suggest less warming during the same interval mann et al 2003a have raised two issues with regard to borehole based reconstructions the first focuses on the need for spatial gridding and area weighting of the ensemble of borehole based gst reconstructions to yield an average hemispheric reconstruction the second asserts that application of optimal detection techniques show that the gst only weakly displays the spatial structure of the surface air temperature sat we demonstrate the consistency of gst warming estimates by showing that over a wide range of grid element area and occupancy weighting schemes the five century gst change falls in the range of 0 89 1 05 k we examine the subhemispheric spatial correlation of gst and sat trends at various spatial scales in the 5 degree grid employed for optimal detection we find that the majority of grid element means are determined from three or fewer boreholes a number that is insufficient to suppress site specific noise via ensemble averaging significant spatial correlation between sat and gst emerges in a 5 degree grid if low occupancy grid elements are excluded and also in a 30 degree grid in which grid element means are better determined through higher occupancy reconstructions assembled after excluding low occupancy grid elements show a five century gst change in the range of 1 02 1 06 k index terms 1645 global change solid earth 1699 global change general or miscellaneous 3309 meteorology and atmospheric dynamics climatology 1620 3322 meteorology and atmospheric dynamics land atmosphere interactions 3344 meteorology and atmospheric dynamics paleoclimatology keywords boreholes paleoclimate spatial analysis surface temperature

the paleozoic minimum of 87sr 86sr ratio in the capitanian permian mid oceanic carbonates a critical turning point in the late paleozoic abstract the secular change in 87sr 86sr ratio of the paleozoic recorded the lowest value below 0 7070 in late middle permian i e the permian minimum suggesting that a major reform in oceanography occurred before the paleozoic mesozoic transition we have detected the correlative lowest 87sr 86sr value 0 706914 0 000012 from the middle upper permian paleo atoll limestone in japan formed primarily on an ancient seamount in mid panthalassa the stratigraphic horizon of the minimum was constrained to the capitanian interval 265 8 260 4 ma middle permian by fusulines as the mid oceanic data represent the global average the present study confirmed the chemostratigraphical utility of the capitanian minimum of 87sr 86sr ratio in global correlation after the long term nearly 280 million years decrease throughout the paleozoic since the cambrian a remarkable turnover of seawater 87sr 86sr values appeared in the capitanian immediately before the guadalupian lopingian middle late permian boundary a major global change likely appeared in the capitanian to change the sr isotope balance in seawater from a mantle flux dominated to a continental flux dominated regime the initial rifting of pangea probably started in the capitanian and the rifting induced new connection of many intra supercontinental drainage systems to the superocean may have caused the overturn in global sr isotopic trend

sr c and o isotopes in carbonate nodules from the ganga plain evidence for recent abrupt rise in dissolved 87sr 86sr ratios of the ganga abstract the evolution of 87 sr 86 sr ratio of the ganga water during the past 100 ka has been reconstructed in this study the 87 sr 86 sr 13 c and 18 o values have been measured in carbonate nodules from different depths of two sediment cores raised from the indian institute of technology kanpur iitk campus 50 m long and jagdishpur jp 25 m long respectively the 87 sr 86 sr ratios of the carbonate nodules range from 0 7142 to 0 7189 in the iitk and 0 7142 to 0 7367 in the jp cores the nodules in general display significantly lower 87 sr 86 sr ratio compared to contemporary ganga river water at kanpur however values of 87 sr 86 sr ratio are observed in the nodules of the jp core near the surface are consistent with that of the present day ganga water at kanpur as well as groundwater samples from adjacent areas indicate recent abrupt increase in 87 sr 86 sr ratio of the ganga these findings are also consistent with the concomitant increase in 87 sr 86 sr ratio of silicates in contemporary sediments of the ganga at kanpur compared to that of past 100 ka the sudden rise of 87 sr 86 sr ratio of the ganga is probably due to increase in the relative proportion of sr from the lesser himalaya containing silicates and carbonates with higher 87 sr 86 sr ratio the cause for the recent increase in sr contribution from the lesser himalaya is not clear this could be due to enhanced agricultural activities and deforestation and or climatic variability during recent times resulting in more erosion in the lesser himalaya the 13 c and 18 o measured in the nodules from the iitk core vary from 6 8 to 1 6 and 8 3 to 5 4 respectively the co variation of 13 c and 18 o suggest the impact of paleoclimate paleovegetation petrography and chemical composition of carbonate nodules indicate little or no diagenetic alteration

optimal surface temperature reconstructions using terrestrial borehole data 1 we derive an optimal northern hemisphere mean surface temperature reconstruction from terrestrial borehole temperature profiles spanning the past five centuries the pattern of borehole ground surface temperature gst reconstructions displays prominent discrepancies with instrumental surface air temperature sat estimates during the 20th century suggesting the presence of a considerable amount of noise and or bias in any underlying spatial sat signal the vast majority of variance in the borehole dataset is efficiently retained by its two leading eigenvectors a sizable share of the variance in the first eigenvector appears to be associated with non sat related bias in the borehole data a weak but detectable sat signal appears to be described by a combination of the first two eigenvectors exploiting this eigendecomposition application of optimal signal estimation methods yields a hemispheric borehole sat reconstruction that is largely consistent with instrumental data available in past centuries and is indistinguishable in its major features from several published long term temperature estimates based on both climate proxy data and model simulations

structure and kinematics of oblique continental convergence in northern fiordland new zealand abstract southeast of the alpine fault in fiordland new zealand late tertiary faults envelope exposures of early cretaceous high p 12 16 kbar granulite facies orthogneisses these exposures allowed us to examine how pre cenozoic structures influenced variations in the degree and style of kinematic partitioning within a zone of oblique continental convergence fault slip data and kinematic modelling show that oblique slip and reverse displacements preferentially were partitioned east of the alpine fault onto curved ne striking surfaces and moderately dipping 30 52 n and nw striking surfaces respectively approximately 3 0 5 5 km of exhumation and 6 5 7 0 km of oblique dextral displacement occurred on faults that display palm tree style geometries and subhorizontal detachments in profile this heterogeneous style contrasts with the near horizontal slip on subvertical surfaces that define the alpine fault north of milford sound the principal axes of instantaneous strain we determined using faults are compatible with principal stress axes derived from earthquakes our data indicate that mechanical anisotropies created by inherited structures controlled the locations and highly variable geometries of faulting since 7 9 ma the effects of these pre existing structures and a focusing of contractional deformation along the northeast margin of fiordland resulted in an unusually high degree of strike slip partitioning across the southernmost onshore segment of the alpine fault

uranium lead ages from the dun mountain ophiolite belt and brook street terrane south island new zealand the dun mountain ophiolite and overlying maitai group is discontinuously exposed for 480 km in south island new zealand zircon u pb dates from plagiogranite are presented for relatively intact ophiolite ophiolitic melanges and for more silicic volcanic plutonic assemblages in the southern part of the belt where a typical ophiolite association is lacking step wise dissolution experiments on slightly discordant plagiogranite zircon produce more concordant residues that indicate the zircons have lost from 1 to more than 5 of their radiogenic pb relatively recently high precision 207 pb 206 pb dates establish the age of ophiolite formation for at least 350 km along strike to a narrow interval between about 275 and 285 ma the zircon u pb data confirm correlation of petrologically distinct segments of the dun mountain ophiolite and show that mafic ultramafic ophiolite assemblages and moderately potassic high level granitoids developed within a short time interval probably during the extension of a volcanic arc marginal basin thick lenses of polymictic breccia and bio clastic limestone of the maitai group locally rest in depositional contact on relatively intact ophiolite within the dun mountain ophiolite comparison of inferred biostratigraphic ages from the limestone with the 280 ma ages from the plagiogranites indicate a gap of 20 m y following ophiolite formation a granite clast from conglomerate higher in the maitai group yielded a near concordant u pb date of 265 ma and provides a maximum age for this part of the sequence attenuation of the dun mountain ophiolite by extensional faulting and erosion may have occurred during the interval between ophiolite formation and maitai group sedimentation the dun mountain ophiolite and overlying maitai group are bounded to the west by triassic and jurassic volcanogenic sedimentary rocks of the murihiku terrane and in turn by the brook street terrane which is interpreted as remnants of an early permian oceanic arc a hornblende gabbronorite associated with a layered mafic ultramafic intrusion in the brook street terrane yielded a date of 265 ma significantly younger than dun mountain ophiolite such intrusions may represent the plutonic roots for ankaramitic volcanic rocks that comprise a conspicuous component of the brook street terrane but which are not represented by detritus in the maitai group biotite granite occurs locally in the brook street terrane and is dated at 260 ma the absence of any clear stratigraphic correlation or provenance linkage between the brook street terrane and dun mountain maitai terrane suggests strike slip displacements on intervening terrane boundary faults

heat as a groundwater tracer in shallow and deep heterogeneous media analytical solution spreadsheet tool and field applications groundwater flow advects heat and thus the deviation of subsurface temperatures from an expected conduction dominated regime can be analysed to estimate vertical water fluxes a number of analytical approaches have been proposed for using heat as a groundwater tracer and these have typically assumed a homogeneous medium however heterogeneous thermal properties are ubiquitous in subsurface environments both at the scale of geologic strata and at finer scales in streambeds herein we apply the analytical solution of shan and bodvarsson 2004 developed for estimating vertical water fluxes in layered systems in 2 new environments distinct from previous vadose zone applications the utility of the solution for studying groundwater surface water exchange is demonstrated using temperature data collected from an upwelling streambed with sediment layers and a simple sensitivity analysis using these data indicates the solution is relatively robust also a deeper temperature profile recorded in a borehole in south australia is analysed to estimate deeper water fluxes the analytical solution is able to match observed thermal gradients including the change in slope at sediment interfaces results indicate that not accounting for layering can yield errors in the magnitude and even direction of the inferred darcy fluxes a simple automated spreadsheet tool flux lm is presented to allow users to input temperature and layer data and solve the inverse problem to estimate groundwater flux rates from shallow e g 1 m or deep e g up to 100 m profiles the solution is not transient and thus it should be cautiously applied where diel signals propagate or in deeper zones where multi decadal surface signals have disturbed subsurface thermal regimes

north american climate of the last millennium underground temperatures and model comparison general circulation models gcms are currently able to provide physically consistent simulations of millennial climate variability in which estimations of external forcing factors are incorporated as boundary conditions climate reconstruction attempts to recover as faithfully as possible past climate variability using a variety of independent and climate sensitive sources of information by deriving strategies of comparison between gcm simulations and proxy data or directly recorded data such as subsurface thermal profiles the agreement between model and observations can be assessed thermal profiles obtained from the boreholes of north america were grouped into eight geographically discrete ensembles and averaged to form robust representative profiles the gridded output from the three distinct integrations of the gcm echo g were similarly averaged by region these simulated millennial paleoclimatic histories were then forward modeled to arrive at the subsurface thermal profiles that would result from the temperature trends at the surface these forward modeled profiles were then compared with the borehole average thermal anomaly profile in each region in most of the regions studied the externally forced runs from echo g are in better agreement with underground temperature anomalies than with the control run suggesting that boreholes are sensitive to external forcing not only do echo g simulations demonstrate better agreement with borehole data when considering variable external forcing factors but echo g also appears to broadly describe qualitative aspects of long term climatic trends at a regional scale

a sulfur and strontium isotopic investigation of lower permian anhydrite palo duro basin texas u s a abstract lower permian wolfcamp and wichita carbonates and anhydrites palo duro basin texas panhandle record a change from a normal marine to marine evaporite depositional environment isotopic compositions of s and sr in anhydrite were determined to investigate the age of wolfcamp and wichita strata and the paragenesis of eight anhydrite forms bedded nodular mosaic wichita and replacive nodular wolfcamp anhydrites have s and sr isotopic compositions that record precipitation from early permian wolfcampian to leonardian seawater silicified nodular coarsely crystalline nodular fossil filling and vein filling anhydrites have enriched s isotopic compositions relative to permian seawater whereas euhedral and anhedral replacive anhydrites have depleted s the sr isotopic composition of most anhydrite forms indicates an early permian marine origin however sr in anhydrite veins is slightly radiogenic compared to permian seawater the sr isotopic compoition of bedded nodular mosaic anhydrite indicates as leonardian seawater source of material the 34 s values are slightly enriched relative to values predicted from the s age curve suggesting an excursion of the s isotopic evolution trend of early permian seawater replacive nodular anhydrite 87 sr 86 sr ratios are slightly higher than those of bedded nodular mosaic anhydrite reflecting incorporation of sr from older marine pore waters or replaced sediments or from dissolution of detrital siliciclastic minerals anhydrite paragenesis is interpreted from stratigraphic mineralogic petrographic and isotopic data bedded nodular mosaic and replacive nodular anhydrite precipitated as marine evaporite strata prograded across underlying normal marine carbonate sediments siliified and coarsely crystalline nodules and anhydrite fossil filling precipitated at essentially the same time as bedded and replacive nodular anhydrite but in environments where sulfate reduction was more extensive euhedral anhedral replacive anhydrite formed in shallower environments where s redox cycling occurred prior to caso 4 precipitation anhydrite vein fills formed last and incorporated radiogenic sr released during alteration of detrital siliciclastic grains

mineralogy geochemistry and petrogenesis of nephrite from tieli china abstract concurrent with the increase in nephrite mining in recent years many new nephrite deposits have been discovered worldwide however studies of these new deposits remain limited to address this knowledge gap the objective of this study was to systematically investigate the nephrite deposit in tieli heilongjiang province china electron probe micro analysis and laser ablation inductively coupled plasma mass spectrometry were used to measure the mineralogical petrological and geochemical characteristics of samples from this deposit the nephrite exhibits a fine and smooth texture with felted blastic and fibroblastic structures indicating high quality compared with nephrites from other deposits the main mineral composition is tremolite with a mg fe2 mg ratio of 0 982 0 992 which is purer than nephrite samples from most other deposits furthermore all tremolite examined in the tieli nephrite has low amounts of cr2o3 0 000 0 060 wt and nio 0 000 0 061 wt relative to dolomite related nephrites the nephrite samples all have very low total rare earth element ree contents ranging from 2 8633 to 10 8375 ppm and are characterized by positive and negative eu anomalies 0 3286 1 4570 light ree enrichment and flat heavy ree the varied ree patterns of the samples highlight the multiple sources of ore forming fluids multistage superimposed mineralization and oxidized mineralization environment the mineral composition of the wall rocks indicates that during formation two typical processes results in nephrite genesis contact and hydrothermal metasomatism generally this nephrite is of a dolomite related origin the discovery of the tieli deposit and this first time systematic study provide a theoretical basis for prospecting nephrite deposits in the study area where intermediate to felsic igneous rocks or si enriched hydrothermal fluids intruded limestone or dolomite marble formed during the variscan indosinian epoch

strontium isotopic signatures of oil field waters applications for reservoir characterization the 87sr 86sr compositions of formation waters that were collected from 71 wells producing from a pennsylvanian carbonate reservoir in new mexico display a well defined distribution with radiogenic waters up to 0 710129 at the updip western part of the reservoir grading downdip to less radiogenic waters as low as 0 708903 to the east salinity 2800 50 000 mg l displays a parallel trend saline waters to the west pass downdip to brackish waters elemental and isotopic data indicate that the waters originated as meteoric precipitation and acquired their salinity and radiogenic 87sr through dissolution of upper permian evaporites these meteoric derived waters descended perhaps along deeply penetrating faults driven by gravity and density to depths of more than 7000 ft 2100 m the 87sr 86sr and salinity trends record influx of these waters along the western field margin and downdip flow across the field consistent with the strong water drive potentiometric gradient and tilted gas oil water contacts the formation water 87sr 86sr composition can be useful to evaluate subsurface flow and reservoir behavior especially in immature fields with scarce pressure and production data in mature reservoirs sr isotopes can be used to differentiate original formation water from injected water for waterflood surveillance strontium isotopes thus provide a valuable tool for both static and dynamic reservoir characterization in conjunction with conventional studies using seismic log core engineering and production data roger barnaby has conducted stratigraphic studies of carbonates and siliciclastics in outcrop and subsurface for 15 years he holds a ph d from virginia polytechnic institute and a b s degree from east carolina university barnaby has worked on sedimentary successions of the gulf coast permian basin alaska north slope middle east and caspian region he maintains interests in carbonate diagenesis and geochemistry gregg oetting received an m a degree in geology in 1995 from the university of texas at austin he is the author of six publications concerning geochemical and strontium isotopic variations in edwards aquifer groundwaters for the past seven years oetting has traded energy futures for leading merchant energy concerns he works for an independent consulting business in houston texas guoqiu gao received his b s and m s degrees in geology from central south university hunan china and his ph d in geology from the university of texas at austin he works for a major oil company in houston texas his current interests lie in the field of geoscience computing

dating penecontemporaneous dolomitization in carbonate reservoirs paleomagnetic petrographic and geochemical constraints the predominant dolomitization in the mississippian debolt formation western canada sedimentary basin was hypothesized to be early in three gas fields based on stable oxygen and carbon isotopic values and on strontium isotope ratios that are similar to postulated mississippian dolomite values and seawater ratios respectively as the absolute age could not be determined by this method paleomagnetism was used to place constraints on the age of the dolomitization the magnetic analyses on debolt specimens from the same wells revealed three magnetization components that could be tied to geologic diagenetic events 1 a low temperature 350 degreesc and coercivity 80 mt c component of primary or early diagenetic origin that is found mostly in the fine grained limestone and dolomitic muds the preservation of a primary or early diagenetic magnetization combined with the preservation of primary isotopic values indicates that little or no extrabasinal fluid flow is likely to have occurred thus in this particular area orogenically induced fluid flow cannot explain the presence of the cretaceous b magnetization consideration of the potential methods for forming this b component suggests that it is likely an in situ chemical remanence resulting from either hydrocarbon migration or dissolution and reprecipitation of fe rich minerals in the original pore fluids

transient lateral heat flow due to land use changes subsurface temperatures have been shown to be useful for obtaining robust reconstructions of climatic changes for the last five centuries recently interest has focused on determining the effects of land use changes on ground surface temperatures gst which could potentially create a bias on these records and should thus be considered in the interpretation of gst reconstructions to date studies have focused on the one dimensional effect of land use changes on heat flow in this study temperature anomalies resulting from lateral heat flow were assessed for different scales of land use change numerical simulations indicate that land use changes over large areas may cause significant changes in subsurface temperatures reaching beyond the extent of the affected area at the surface we provide guidelines for future surveys and for correcting existing data d 2005 elsevier b v all rights reserved

87sr 86sr ratios in permo carboniferous sea water from the analyses of well preserved brachiopod shells abstract sr isotopic analyses of well preserved portions of permo carboniferous brachiopods distributed globally confirm the general shape of the sr isotope age curve established by previous workers for this time interval there is little variation between the sr isotopic composition of unaltered portions of brachiopods and that of portions of the same shell interpreted to be diagenetically altered based on cathodoluminescence elemental and stable isotopic data however the sr isotopic composition in diagenetically altered micritic matrix adjacent to the shell is more radiogenic the sr isotopic composition in the unaltered portions of calcitic megafossils has potential as a stratigraphie tool

tracing deep fluids in the bozhong sag evidence from integrated petrography and geochemistry data abstract the bozhong sag is a mature exploration area for petroleum in the bohai bay basin china which is a typical oil bearing basin and hosts the penglai pl 19 3 and qinhuangdao qhd 32 6 giant oil fields xue 2018 despite 60 years of hydrocarbon exploration in the basin only few large gas fields have been discovered the discovery of the bozhong bz 19 6 gas field not only indicated that the bozhong sag has great potential for natural gas exploration but also raised questions regarding the formation of large scale natural gas fields in typical oil prone basins and in sapropelic source rocks the present study therefore performs a detailed investigation of the sources and migration pathways of the deep fluids in the bozhong sag area as a means of shedding light into this scientific challenge the bozhong sag is located in the thinnest crust and tectonic transition zone of the bohai bay basin intense extension and thinning of lithosphere led to the upward ejection of deep crust and mantle materials under diapirism improvements in this tectonic setting and the fluid migration path occurred as a result of early faults that were formed by compressive thrust in the indosinian yanshan orogenies in addition to a process of extensional development and reactivation of himalayan faults we obtained cores from 13 wells in the bozhong sag and subsequently observed their petrography and analyzed samples for fluid inclusions also volcanic rock samples were analyzed for major and trace elements and carbonate rock samples were analyzed for 13c 18o and 87sr 86sr previously reported 13cco2 and he isotopic data were are also discussed our results showed that petrography was characterized by thermal fading and hydrothermal breccia around fractures filled with quartz and calcite deep fluid activity was mainly reflected by petrographic assemblages of quartz ankerite pyrite plus calcite and volcanic eruptive rocks that were i enriched with large ion lithophile elements lile ii enriched with light rare earth elements lree iii relatively deficient in high field strength elements hfse and iv relatively deficient heavy rare earth elements hree thermal anomaly events were reflected by the homogenization temperature of fluid inclusions and characteristics of magmatic hydrothermal fluids were exhibited by 13c 18o and 87sr 86sr our findings indicated that deep fluids were mainly derived from the deep parts of the upper mantle and that they were slightly contaminated by crustal materials combining our results with those of previous studies on deep xenoliths and xenolithic fluid compositions in eruptive rocks of eastern china zhang et al 1999 han et al 2008 we interpreted that deep fluid properties in the study region were characterized by high h2 and low total volatile gases we conclude that the deep fluids in the bozhong sag was mainly derived from deep material in the upper mantle and that the fluid activity pattern was aided by the deep fracture fault systems in addition to central and fissure type wide area eruption activities

slab derived origin of tremolite antigorite veins in a supra subduction ophiolite the peridotite nappe new caledonia as a case study hydration of mantle peridotites provides information on the exhumation history and on the fluid regime accompanying exhumation of these rocks reservoirs involved fluid rock ratios temperature of interaction highly depleted harzburgites and dunites of the peridotite nappe of new caledonia are crosscut by fractures which have been pervasively serpentinized producing lizardite brucite magnetite and minor chrysotile in a near static environment probably by sea water circulating in cooling joints this event is generally referred to as primary serpentinization in a next step already serpentinized joints were re opened to produce tension and shear cracks sealed by higher temperature synkinematic fibrous minerals locally tremolite bearing veins and pockets which do not display evidence for void infill were generated by metasomatic replacement of the wall rock peridotite most veins only contain fibrous antigorite but some display tremolite antigorite intergrowths or even pure tremolite the latter rocks yield high contents of ca and incompatible elements which contrast with the overall depletion of the peridotite host rock and suggest contribution of an external source whole rock geochemical and isotopic features 87sr 86sr 18o and h suggest that antigorite veins which bear highly radiogenic sr isotope signatures were strongly influenced by fluids emitted by the subducted slab and associated sediments in contrast the geochemical and isotopic signatures of tremolite bearing rocks suggest a genetic link with early eocene supra subduction dykes and fluids that leached them calcium strontium and ree bearing oxidized fluids reacted with already serpentinized fracture wall rock as shown by fibre nucleation chromite alteration and high cr contents in tremolite the bulk of syn tectonic fluid rock interaction associated with shear and tensile fracture development probably occurred at the onset of eocene intra oceanic subduction when the buoyant lower plate the south loyalty basin obliquely forced its way beneath the nascent loyalty fore arc mobile elements extracted from supra subduction dykes temporarily enriched the circulating fluids and generated tremolite antigorite mg chlorite and magnetite instead of antigorite and magnetite solely tremolite crystallization probably ceased due to the exhaustion of ca rich fluids in a globally cooling fore arc environment

87sr86sr isotopic evolution of lower carboniferous seawater dinantian of western europe abstract the chemical and isotopic evolution of ocean water mirrors the dynamics of the earth system the original seawater signature can be measured only indirectly for the palaeozoic samples with the greatest utility for such an approach are the secondary layers of articulate brachiopods for a correct interpretation of isotope data samples that have suffered alteration by diagenetic processes must be avoided trace element analysis is frequently utilized as an analytical tool the present study deals with the delineation of a detailed 87 sr 86 sr curve for the dinantian this in turn enables us to search for causative factors of the observed isotopic oscillations a total of 175 lower carboniferous dinantian brachiopod shells from a variety of western european locations have been analysed for their 87 sr 86 sr ratios for 152 of these shells quantitative geochemical tests on diagenetic alteration based on trace element repartitioning during recrystallisation have been performed the concentrations of ca mg sr mn and fe were routinely measured by inductively coupled plasma atomic emission spectroscopy icp aes analysing the diluted phosphoric acid that remained after carbonate dissolution for stable isotope gas preparation in addition 71 samples have been analysed by proton induced x ray emission spectroscopy micro pixe despite large differences in the analysed masses 3 6 mg for icp aes as low as 10 ng for pixe both methods yield comparable data for the sr and mn contents any discrepancies can be related to inhomogeneities of the shells e g punctae of these shells 73 have sr and mn contents of 600 ppm and the sr isotope record of the dinantian seawater is characterised by a decline in 87 sr 86 sr ratio from 0 7082 at the devonian carboniferous transition to 0 7076 in the mid visean superimposed on this trend are higher order fluctuations with a periodicity in the ma range the dinantian seawater curve may potentially serve as a geochronological and correlation tool particularly for the hastarian to lower chadian interval where the attainable resolution is 1 ma this is better than the resolution available by biostratigraphy the higher order wiggles for the most part can be generated by changing the riverine flux of sr or its isotopic ratio within reasonable geological scenarios some spikes however are too large and too short to be explained by the above phenomena these apparent spikes may reflect instead the fact that their duration has been underestimated due to unreliable geochronology and or the presence of unrecognised hiatuses

modelling the phanerozoic carbon cycle and climate constraints from the 87sr 86sr isotopic ratio of seawater a numerical model describing the coupled evolution of the biogeochemical cycles of carbon sulfur calcium magnesium phosphorus and strontium has been developed to describe the long term changes of atmospheric carbon dioxide and climate during the phanerozoic the emphasis is on the effects of coupling the cycles of carbon and strontium various interpretations of the observed phanerozoic history of the seawater 87sr 86sr ratio are investigated with the model more specifically the abilities of continental weathering volcanism and surface lithology in generating that signal are tested and compared it is suggested that the observed fluctuations are mostly due to a changing weatherability over time it is shown that such a conclusion is very important for the modelling of the carbon cycle indeed it implies that the conventional belief that the evolution of atmospheric carbon dioxide and climate on a long time scale is governed by the balance between the volcanic input of co2 and the rate of silicate weathering is not true rather carbon exchanges between the mantle and the exogenic system are likely to have played a key role too further the increase of the global weathering rates with increasing surface temperature and or atmospheric co2 pressure usually postulated in long term carbon cycle and climate modelling is also inconsistent with the new model other factors appear to have modulated the weatherability of the continents through time such as mountain building and the existence of glaciers and ice sheets based on these observations a history of atmospheric carbon dioxide and climate during phanerozoic time consistent with the strontium isotopic data is reconstructed with the model and is shown to be compatible with paleoclimatic indicators such as the timing of glaciation and the estimates of cretaceous paleotemperatures

airflow within major alpine river valleys under heavy rainfall summary this study documents the aire ow within major alpine river valleys in the presence of precipitation the analysis seeks a conceptual understanding of the effect of rain on the valley e ow ground based and airborne doppler radar and surface data from the mesoscale alpine programme show that during persistent rainy periods the subsidence caused by melting and evaporation of precipitation particles contributes to the formation of a down valley e ow this down valley eow opposes moist southerly e ow aloft which is lifted over the topographic barrier and in which precipitation particles are formed

himalayan tectonics weathering processes and the strontium isotope record in marine limestones the time evolution of the isotopic composition of seawater strontium the ratio of strontium 87 to strontium 86 over the last 500 million years has the form of an asymmetric trough the values are highest in the cambrian and recent 0 7091 and lowest in the jurassic 0 7067 superimposed on this trend are a number of smaller oscillations consideration of the geochemical cycle of strontium and the dynamics of weathering shows that only himalayan style continental collisions can influence the isotope ratio on the scale observed the contemporary himalayan orogeny is by far the largest since the late precambrian pan african event that produced the high in the cambrian

cloud water in windward and leeward mountain forests the stable isotope signature of orographic cloud water 1 cloud water can be a significant hydrologic input to mountain forests because it is a precipitation source that is vulnerable to climate change it is important to quantify amounts of cloud water input at watershed and regional scales during this study cloud water and rain samples were collected monthly for 2 years at sites on windward and leeward east maui the difference in isotopic composition between volume weighted average cloud water and rain samples was 1 4 18o and 12 2h for the windward site and 2 8 18o and 25 2h for the leeward site with the cloud water samples enriched in 18o and 2h relative to the rain samples a summary of previous literature shows that fog and or cloud water is enriched in 18o and 2h compared to rain at many locations around the world this study documents cloud water and rain isotopic composition resulting from weather patterns common to montane environments in the trade wind latitudes an end member isotopic composition for cloud water was identified for each site and was used in an isotopic mixing model to estimate the proportion of precipitation input from orographic clouds orographic cloud water input was 37 of the total precipitation at the windward site and 46 at the leeward site this represents an estimate of water input to the forest that could be altered by changes in cloud base altitude resulting from global climate change or deforestation

the isotopic composition of strontium and sulfur in seawater of late permian zechstein age abstract the paleozoic minima of 87 sr 86 sr ratios and 34 s values in seawater are observed in anhydrite layers of the stassfurt a 2 and aller a 4 cycles of evaporation of late permian age in germany these minima were probably caused by extremely low rates of continental runoff and bacterial sulfate reduction thereafter conditions changed suddenly with a steeply increasing supply of radiogenic sr and of nutrients into seawater the latter induced a large growth in the production of organic material in bacterial activity in sediments and in the flow of isotopically heavy sulfur back into the oceans this large change in the cycles of s and sr as well as of c and o within the relatively short zechstein period 2 5 ma reflects a considerable modification of the plate tectonic and environmental conditions shortly before the beginning of the mesozoic era the ochoan deposition in the usa is probably of the same age as the stassfurt leine evaporation in w europe

cloud top entrainment instability mixing processes at cloud boundaries are thought to play a critical role in determining cloud lifetime spatial extent and cloud microphysical structure high fidelity direct numerical simulations by mellado j fluid mech 2010 this issue vol 660 pp 5 36 show for the first time the character and potency of a curious instability that may arise as a result of molecular mixing processes at cloud boundaries an instability which until now has been thought by many to control the distribution of climatologically important cloud regimes

seawater sr isotope variation over the past 300 kyr and influence of global climate cycles the past 300 000 years have been characterized by glacial inter glacial fluctuations accompanied by glacio eustatic changes in sea level and changes in continental erosion arising from varying low latitude rainfall and river drainage here we use measurements of strontium isotopes in foraminifera and corals to place limits on variations in the sr isotope composition of sea water in response to these changing inputs we find small variations of about 20 p p m in the 87sr 86sr ratio which for the foraminiferal record seem to follow a cycle close to the 100 kyr periodicity seen for a number of other climate related phenomena these are superimposed on a general increase in87sr 86sr through the cenozoic to the present on short timescales these changes are likely to be controlled by variations in the global riverine sr flux and thus by weathering rates rather than in the hydrothermal sr flux at mid ocean ridges we show that transient variations over a 50 kyr timescale can be explained on the basis of the present day global drainage system in conjunction with the perturbations expected to accompany climate changes over the past 300 kyr

radiogenic isotopes systematics and applications to earth surface processes and chemical stratigraphy radiogenic isotopes have wide application to chemical stratigraphy geochronology provenance studies and studies of temporal changes in earth surface processes this paper briefly reviews the principles of radiogenic isotope geochemistry and the distribution of a number of elements of interest in the environment and then uses this information to explore the range of applications to chemical stratigraphy and other fundamental subjects of sedimentary geology many of these applications center on the reconstruction of secular variations in paleoseawater isotope signals these seawater isotope curves can be used for stratigraphic correlation and to assess changes through earth history in processes such as tectonic uplift climate change biogeochemical cycling ocean circulation crustal growth and surface water evolution understanding the modern biogeochemical cycle of the element isotope system of interest is essential for gaining the maximum information regarding the operation of ancient cycles the main sources of uncertainty for reconstructing seawater isotope curves involve diagenetic alteration sample impurities and errors in age assignments rigorous sample selection criteria and pretreatment methods are keys to reconstructing the most accurate seawater isotope curves applications are discussed for the rb sr sm nd la ce lu hf re os u th pb k ar and cosmogenic isotope systems d 2003 elsevier b v all rights reserved

transient thermal effects below complex topographies abstract the topographical perturbation of steady state subsurface temperature fields has been an important issue in geothermal interpretations throughout the past century this paper reports a numerical study which considers the possible influence of terrain topography on transient temperature signals typical morphological situations over wide areas in central europe affect most likely that same depth range which also contains the temperature signals resulting from the most interesting ground surface temperature changes i e during the last 200 years the evaluation of the interaction is performed on a synthetic sinusoidal topography with varying wavelength and amplitude vertical profiles i e temperature logs were extracted from these numerical forward 2 d calculations thereby the error could be estimated by comparing ground surface temperature time histories inverted from temperature logs both with and without topographic correction the results show that a topographic correction of temperature data is absolutely necessary to achieve a consistent inversion result even rather flat topographies with 20 km wavelengths and 100 m amplitudes may introduce topographical effects which confuse the inversion process on the other hand the palaeoclimatically induced temperature signal persists even in rough topographies and will show correct inversion results when data are adequately treated only extreme situations cause a lateral interference of these transient signals with depth the results from such 2 d synthetic models have been confirmed by an analysis of a real situation the example chosen is the area surrounding the german continental deep drilling ktb project the area is situated in a moderately undulating surface topography with maximum altitude variations of the order of 250 m the additional 3 d simulation demonstrates that a strong topography dependent variation of the transient temperature signal can occur even at greater depths the introduction of corrections for topography influence reduces apparent differences in profiles from different locations in the surroundings of the ktb site to a maximum of 0 2 k

on the dynamics of hawaiian cloud bands island forcing abstract this study focuses on basic island scale forcing mechanisms for the formation and evolution of a band cloud typically present upwind of the island of hawaii by means of numerical experiments and verification of our results against observations and laboratory experiments reported in the literature we show that the band cloud is a complex three dimensional phenomenon which is inseparable from the airflow around the island in particular we demonstrate that the event needs to be analyzed in terms of the basic fluid dynamics of strongly stratified flow past a three dimensional obstacle the band cloud is found to arise primarily from the dynamic interaction of the trade winds with the island the upwind surface flow forms a separation line with an associated stagnation point a low level convergence zone forms along this line resulting in an updraft line if the updrafts are strong enough a band cloud forms formation and characteristics of such a system are mostly controlled by the environmenta

waulsortian like mounds of the mississippian pekisko formation northwestern alberta petrographic and chemical attributes abstract the tournasian age pekisko carbonates in the normandville field northwestern alberta form waulsortian like bryozoan crinoid mounds that developed in fairly deep low energy cool water systems close to the ramp margin three main depositional environments occur 1 crinoidal apron with wackestone grainstone and floatstone facies 2 mound flank with grainstone wackestone packstone and floatstone facies dipping 35 and 3 bryozoan mound core composed of rudstone and floatstone facies with fenestrate bryozoa minor crinoids and carbonate mud local highs due to fault bounded blocks created from the collapse of the devonian peace river high may have controlled the location of mound nucleation diagenesis of the bryozoan crinoid mounds included calcite cementation compaction dolomitization silicification and hydrocarbon emplacement events the mound core facies contains submarine fascicular optic calcite and bladed prismatic calcite cements and later ferroan brightly luminescent pore filling blocky spar cement the crinoid apron facies contains syntaxial cement associated with crinoids and the ferroan blocky spar cement the mounds are dominantly limestone however in one well dolomite dominates the lower section four types of dolomite have been identified partial replacive chemical compaction related pervasive dolomite and saddle dolomite cement all dolomites are non stoichiometric caco3 mole 56 6 62 6 the partial zoned replacive dolomite replaces micrite and syntaxial rim calcite in mound flank and crinoid apron facies the chemical compaction related dolomite is found along dissolution seams and stylolites and has similar cl characteristics to the replacive dolomite the pervasive dolomite is fabric destructive and has dull cores and bright rims in cl saddle dolomite 0 15 mm has brightly luminescent concentric zoning and occurs in vugs and fossil pore spaces chemical and isotopic analysis of the bryozoan crinoid mounds indicate that the original marine signatures in micrite early cements some crinoids and brachiopods have been preserved however carbon isotopic values for some crinoids matrix and dolomite show more positive values compared to known mississippian carbonate values recrystallization during shallow burial has reset the oxygen isotopic composition of some crinoids and micrite oxygen and carbon isotopic compositions of most dolomites overlap with altered crinoids and early calcite cements however saddle dolomites have lighter 18o values similar to saddle dolomites from the devonian wabamun group in this area the isotopic variations in later ferroan calcite cements show an inverted j trend possibly due to variable amounts of water rock interaction while the sr isotopic ratio of submarine calcite cement coincides with that of mississippian seawater the later ferroan calcite cement is more radiogenic indicating a different source of fluids

sulfur geochemistry across a terrestrial permian triassic boundary section in the karoo basin south africa concentrations of sulfur and carbon and isotopic compositions of sulfur were determined in sedimentary rocks from a section across the terrestrial permian triassic p tr boundary in the northern karoo basin south africa high concentrations of sulfide produced by sulfate reducing bacteria were found in the sedimentary rocks at and just below the perceived p tr boundary the ratios of organic carbon to sulfide of the sedimentary rocks with high concentrations of sulfide are relatively constant and similar to those of marine environments this means that the enhanced accumulation of sulfide is a result of the enrichment of sulfate in the water as the sulfide concentrations do not correlate with concentrations of any major elements indicative of weathering intensity the supply of sulfate was independent of environmental factors such as temperature and co2 concentrations in the atmosphere which control weathering intensity therefore it is reasonable to consider that the sulfate might have been supplied to the freshwater directly as acid rain by an event such as a bolide impact or a volcanic eruption the absence of evidence for an impact event in the geological record though favors volcanic input as the cause of the acid rain

on the dynamics of hawaiian cloud bands comparison of model results with observations and island climatology abstract this paper presents a detailed comparison study of three dimensional model results with an aircraft wind field mapping for the island of hawaii model runs were initialized using an aircraft sounding from 1 august 1985 and detailed predictions from the model are compared with observations from that day the strength and location of the upwind convergence zone were well simulated as well as the strong deflection and deceleration of the flow around the island and the geometry and location of the upstream cloud bands the good agreement between the model results and observations supports the results of our previous study in which we show that the flow pattern and associated cloud processes around the island of hawaii can be understood by considering the flow of a stably stratified fluid around a large three dimensional obstacle model runs with different wind directions showed that increasing northerly tradewind flow resulted in the band clouds moving closer to the shore line and the large scale

construction of the mississippian pennsylvanian and permian seawater 87sr86sr curve abstract the estimated path of seawater 87 sr 86 sr during the mississippian pennsylvanian and permian is based on 228 analyses the samples are largely from the southern interior of the u s a where rocks of this age are widely exposed multiple analyses from single rock units are used to define the seawater ratio for different time periods the seawater 87 sr 86 sr declines from 0 70812 sw 95 mississippian to an estimated low in the early meramecian of near 0 70755 sw 152 the value rises to near 0 70812 sw 95 in latest mississippian the ratio rises to 0 70830 sw 77 in mid pennsylvanian and decreases to near 0 70809 sw 98 during virgilian time the earliest permian value is near 0 70793 sw 114 after rising to 0 70804 sw 103 in the early leonardian the seawater 87 sr 86 sr falls sharply to reach a low of 0 70672 sw 235 in ochoan time the end of the paleozoic is estimated to be near 0 70707 sw 200 based on samples from china analysis of the paleozoic curve shape shows an alternating dominance of oceanic and continental sr contributions the extended and precipitous decline in the 87 sr 86 sr during mid permian is unmatched during the phanerozoic the contrast of the paleozoic seawater sr curve shape to that in the mesozoic and cenozoic indicates a potentially fundamental change in the balance of oceanic and continental sr contributions at the end of the permian

mid mountain clouds at whistler during the vancouver 2010 winter olympics and paralympics a comprehensive study of mid mountain clouds and their impacts on the vancouver 2010 winter olympics and paralympics is presented mid mountain clouds were frequently present on the whistler alpine venue as identified in an extensive archive of webcam images over a 45 day period from february 5 to march 21 2010 these clouds posed serious forecast challenges and had significant impacts on some olympic and paralympic alpine skiing competitions under fair weather conditions a diurnal upslope anabatic flow can work in concert with a diurnal temperature inversion aloft to produce a localized phenomenon known as harvey s cloud at whistler two detailed case studies in this paper suggest that mid mountain clouds can also develop in the area as a result of a moist valley flow interacting with a downslope flow descending from the mountaintop a southerly inflow through the sea to sky corridor can be channeled by the local topography into a westerly upslope flow toward whistler mountain resulting in orographic clouds on the alpine venue under favorable circumstances these clouds are trapped to the mid mountain zone by the leeward subsidence of an elevated southerly flow the presence of the downslope subsidence was manifested by a distinguished dry layer observed on the top of the mid mountain clouds in both cases it is the subsidence induced adiabatic warming that imposes a strong buoyant suppression to trap the mid mountain cloud on the other hand the subsidence induced dry layer has the potential to trigger evaporative instability to periodically breakup the mid mountain cloud

surface heat flux histories from inversion of geothermal data energy balance at the earth s surface past changes in the earth s surface energy balance propagate into the subsurface and appear as perturbations of the subsurface thermal regime this paper presents a singular value decomposition inversion method used to reconstruct surface heat flux histories shfh from the heat flux anomalies detected in the shallow subsurface synthetic tests were used to assess the robustness of the inversion procedure it was found that data noise can have a significant effect on the stability of the shfh inferred from inversion this translates in shfhs having lower temporal resolution than ground surface temperature histories gsths obtained from the same data but the long term trends are robust results are encouraging for temperature data noise levels typically encountered in field measurements synthetic data tests yield results in agreement with analytical expressions derived from gsths for the same parameterization temperature depth profiles from canada s geothermal database were used to illustrate the inversion procedure individual temperature profile inversions are shown as examples all 112 temperature logs in the database were used to obtain a mean heat flux history for the region results indicate that the ground heat flux has increased an average of 24 mw m 2 over the last 200 years in canada application of this method to the existing global geothermal data base should allow for a quantification of the global energy balance at the earth s surface for the past few centuries and may be useful for land surface models

strontium isotope diagenesis of biogenic aragonite and low mg calcite abstract using petrographie and geochemical criteria it is possible to identify marine sr isotopic compositions and diagenetic overprints in carbonate samples the 87 sr 86 sr ratio of originally low mg calcite brachiopods and aragonite molluscs from the boggy magoffin and brush creek formation members increases with progressive post depositional alteration in the presence of diagenetic meteoric waters in contrast brachiopods from the codroy formation exhibit an increase in non radiogenic sr with diagenetic alteration based on the seawater 87 sr 86 sr curve this alteration probably occurred in the presence of marine water during the mid permian triassic or late cretaceous early tertiary the degree of change in radiogenic sr probably reflects the physicochemical nature of the diagenetic microsystem diffusion controlled altered material shows the smallest degree of change in sr isotopic ratios as well as microstructural and other geochemical modifications in contrast fluid controlled altered material shows the greatest shift in isotopic ratios with concomitant microstructural and geochemical changes data of diagenetically well defined biogenic carbonates show that mississippian seawater 87 sr 86 sr was constant with a mean of about 0 70773 and a range of 0 7076 0 7078 the revised high resolution curve shows significantly higher variations for pennsylvanian seawater 87 sr 86 sr 0 7076 0 7093 a low perturbation marks the midvirgilian 0 7076 0 7078 and high perturbations are observed for the early missourian 0 70846 and latest morrowan 0 70913 the mean value determined for the latest morrowan is similar to 87 sr 86 sr ratios measured for modern carbonates and seawater it is further suggested that seawater 87 sr 86 sr varies by as much as 0 000154 at any given time

the influences of inversion height on precipitation and airflow over the island of hawaii abstract both the daily rainfall on the windward side of the island of hawaii and the early morning 0200 hst hawaiian standard time trade wind inversion height at hilo varied substantially during the hawaiian rainband project harp in general the inversion was higher during the passage of a cold front to the north or during the approach of tropical disturbances from the east to the south the daily rainfall on the windward side is highly correlated with the 0200 hst inversion height at hilo with a maximum correlation greater than 0 7 in the hilo area the daily daytime 1100 1900 hst rainfall on the windward slopes nocturnal 1900 0300 rst showers an the windward lowland and coastal precipitation in the predawn and early morning hours 0300 1100 hst are also highly correlated with the inversion height with a maximum correlation greater than 0 7 0 7 and 0 5 respectively for the low high inversion days the median daily rainfall on the windward side is about one half more than twice of t

the strontium isotopic composition of brigantian late dinantian seawater abstract strontium isotopic determinations of different fossiliferous biominerals from brigantian late dinantian carbonates in northern england reveal that many are affected by diagenetic overprinting of their original 87 sr 86 sr ratios only pristine non luminescent articulate brachiopod shell material can be used to gain reliable estimates of carboniferous and by deduction palaeozoic ocean chemistries conodonts are found to be the only type of phosphatic biomineral capable of preserving original palaeoseawater chemistries however this only applies to specimens subjected to minimal burial temperatures other phosphatic biominerals are conclusively shown to be readily susceptible to diagenetic overprinting of original sr isotopic ratios a brigantian strontium curve compiled from pristine brachiopod calcite shows a relatively complex evolution with time but it can be resolved into two separate components operating on different time scales a cyclic sinusoidally shaped component with a frequency of 1 ma appears to fluctuate about a longer term more gradual linear increase in the brigantian seawater isotopic composition

chemostratigraphy of the mid carboniferous boundary global stratotype section and point gssp bird spring formation arrow canyon nevada usa abstract the iugs in 1998 decided that the mid carboniferous mississippian pennsylvanian global boundary stratotype section and point gssp be assigned to a sequence of sedimentary units within the lower bird spring formation in arrow canyon nevada usa with the boundary defined by the first appearance of declinognathodus noduliferus this study represents the geochemical work on brachiopods matrix and cement covering a 35 m interval of the gssp about the mid carboniferous boundary samples were collected wherever brachiopods were noted in the sequence interval and their stratigraphic position was carefully measured using the a markers left by amoco geologists from their detailed biostratigraphic work the mean chemostratigraphic 1000 sr ca value of unaltered brachiopods from the mississippian side of the boundary 1 928 0 575 are similar to their pennsylvanian counterparts 2 141 0 427 and both are within the range of values obtained for recent low latitude brachiopods 1 50 to 5 50 manganese concentrations are similar with mean values of 33 mg kg and 27 mg kg for mississippian and pennsylvanian boundary brachiopods respectively and fall well within the manganese range of recent low latitude representatives 4 to 58 mg kg in contrast mississippian unaltered boundary brachiopods 244 125 mg kg contain significantly more fe p 0 001 than pennsylvanian ones 141 97 mg kg although both of these averages are above there is some overlap in their ranges with that recorded for fe in recent counterparts 10 to 127 mg kg oxygen isotope values of unaltered brachiopods from the mississippian side of the boundary 2 38 0 82 pdb are similar to the pennsylvanian ones 2 19 0 72 pdb and well within the range recorded in recent low latitude specimens 3 04 to 0 40 pdb carbon isotope values for the mississippian boundary brachiopods 2 01 0 81 pdb are dissimilar to those from the pennsylvanian 2 42 0 83 pdb but both are within the range observed in recent low latitude brachiopods 0 94 to 3 11 pdb the 1000 sr ca mn fe 13c and 18o values contents of the unaltered brachiopods reflect oceanographic conditions of the arrow canyon sea and as such are valuable proxies for local and possibly regional basin correlation at this time the 87sr 86sr values of unaltered brachiopods provide the most useful geochemical tool in recognizing and correlating the mid carboniferous boundary on a global scale the frequency and variations of the mississippian 87sr 86sr trend 0 708 082 0 000 040 are pronounced and significantly different p 0 045 from the essentially invariant trend for the post boundary pennsylvanian 0 708 123 0 000 031 brachiopods from the gssp the mid carboniferous boundary 87sr 86sr value based on unaltered brachiopod samples from within 1 m of the boundary is 0 708 056 0 000 021

a multitaxic bonebed near the carboniferous permian boundary halgaito formation cutler group in valley of the gods utah usa vertebrate paleontology and taphonomy abstract the carboniferous permian c p transition records a shift in the composition and environmental setting of tropical flora and vertebrate assemblages across western and central pangea here we report the discovery of a rare multitaxic bonebed in the lower halgaito formation cutler group in valley of the gods and its vicinity san juan county southeast utah usa the assemblage which comprises carcasses and disarticulated bones and teeth preserves aquatic and semi terrestrial elements including xenacanth chondrichthyans actinopterygians sagenodontid lungfish and the temnospondyl amphibian eryops together with terrestrial taxa including the synapsids ophiacodon navajovicus edaphosaurus and sphenacodon and a hitherto undescribed araeoscelidan reptile sedimentological paleontological and strontium isotopic evidence indicates the bonebed formed as a slackwater deposit at the confluence of a major freshwater stream channel and its tributary the deposit probably formed through late stage flooding of a likely bottlenecked fluvial system consistent with increasingly episodic or seasonal precipitation concentrating carcasses of immature and mature shore dwelling animals comparisons with vertebrate assemblages in the cutler group of new mexico usa suggest that the assemblage is correlative with the lower or middle assemblage of the el cobre canyon formation cobrean and coyotean land vertebrate faunachrons lvfs and as such is of latest carboniferous age our findings strengthen the hypothesis that dryland adapted vertebrate communities proliferated earlier in westernmost pangea well before earliest permian time compared to other tropical regions

reconstruction of cave air temperature based on surface atmosphere temperature and vegetation changes implications for speleothem palaeoclimate records abstract cave temperature is a parameter of major importance for palaeoclimate studies based on speleothems since most proxies used are temperature dependent the general assumption that cave temperature reflects the mean annual surface atmosphere temperature sat over the cave is based on a limited number of specific studies and detailed mechanisms supporting this link are not properly described eagle cave in spain was used to understand the detailed mechanisms connecting sat and cave temperature a monitoring programme conducted from 2009 to 2011 allows the characterization of the thermal dynamics in the cave air in the studied karstic environment thermal conduction is the main mechanism responsible for transferring the ground temperature signal to the cave the calculated thermal diffusion coefficient is 0 756 10 6 0 013 m 2 s 1 the sat signal is recorded at the cave with a delay ranging from 3 to 11 yr depending on the thickness of the bedrock over the ceiling 5 18 m a cave cooling of 2 c has been recorded since mid 1970s when cave temperature measurements were made the application of a model exclusively based on thermal conduction of sat does not reproduce the observed thermal changes however vegetation cover over the cave was modified dramatically during recent decades this impacts ground temperature due to the changes in exposure to insolation and the modification of soil properties which is eventually recorded in the cave the incorporation of changes in vegetation cover in the model provides a realistic thermal reconstruction the impact of vegetation cover was much more significant than sat in order to explain the large thermal change in the cave over past decades thus the cooling in eagle cave during past decades is mainly controlled by a variable decoupling from mean annual sat as a result of the afforestation over the cave the effect of this thermal decoupling on speleothem 18 o records is potentially significant and should be considered when performing accurate palaeoclimate reconstructions

orographic effects on precipitating clouds 1 precipitation over and near mountains is not caused by topography but rather occurs when storms of a type that can occur anywhere deep convection fronts tropical cyclones form near or move over complex terrain deep convective systems occurring near mountains are affected by channeling of airflow near mountains capping of moist boundary layers by flow subsiding from higher terrain and triggering to break the cap when low level flow encounters hills near the bases of major mountain ranges mesoscale convective systems are triggered by nocturnal downslope flows and by diurnally triggered disturbances propagating away from mountain ranges the stratiform regions of mesoscale convective systems are enhanced by upslope flow when they move over mountains in frontal cloud systems the poleward flow of warm sector air ahead of the system may rise easily over terrain and a maximum of precipitating cloud occurs over the first rise of terrain and rainfall is maximum on ridges and minimum in valleys if the low level air ahead of the system is stable blocking or damming occurs shear between a blocked layer and unblocked moist air above favors turbulent overturning which can accelerate precipitation fallout in tropical cyclones the tangential winds encountering a mountain range produce a gravity wave response and greatly enhanced upslope flow depending on the height of the mountain the maximum rain may occur on either the windward or leeward side when the capped boundary layer of the eye of a tropical cyclone passes over a mountain the cap may be broken with intense convection resulting

mineralogy geochemistry and petrogenesis of nephrite from panshi jilin northeast china abstract nephrite is an important variety of jade that is of great significance in prospecting management little research has been carried out on the newly discovered nephrite deposit in panshi jilin province northeast china this paper presents the first systematic study of this new deposit the mineralogical petrological and geochemical characteristics along with the petrogenesis of samples from this deposit were evaluated by microscopic observation scanning electron microscopy electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry the main mineral component of the panshi nephrite was determined to be tremolite and diopside chlorite apatite calcite and dolomite were observed as secondary minerals the tremolite presented two microstructures feltlike and fibroblastic all the examined tremolite samples contained low amounts of feo 0 006 0 249 wt cr2o3 0 000 0 047 wt and nio 0 000 0 053 wt along with high values 0 99 of mg2 mg2 fe2 relative to dolomite related nephrites the nephrite samples all exhibited very low total rare earth element contents ranging from 1 831 to 5 121 ppm and were characterized by positive and negative eu anomalies 0 267 4 446 negative ce anomalies 0 283 0 650 positive u anomalies and negative ba nb ti and ce anomalies these characteristics indicate a multistage superimposed mineralization formation mechanism for the panshi nephrite the test results and regional geological survey results indicate that the panshi nephrite deposit was likely formed by intermediate felsic magmas that intruded into dolomitic marble in many stages during the variscan indosinian epoch generally the genesis of the panshi nephrite can be ascribed to two typical processes contact metasomatism and late metamorphism and the panshi nephrite is of dolomite related origin the results of this study provide theoretical guidance for the search for nephrite deposits of dolomite related origin

paleoenvironmental changes across the carnian norian boundary in the black bear ridge section british columbia canada abstract the black bear ridge section in northeastern british columbia canada consists of a continuously exposed sequence of upper carnian through lower norian upper triassic continental margin strata the section has been proposed as a candidate global stratotype section and point gssp for the carnian norian boundary cnb in order to assess late carnian to early norian environmental changes recorded in the section we examined stratigraphic variations in 87sr 86sr 13c and 18o values and also values of redox sensitive elements v ni and cr in the cnb interval the study section is located along the north shore of williston lake northeastern british columbia the black bear ridge section was deposited in a distal ramp environment on the passive western margin of the north american craton the strata across the cnb display a positive shift in 13c values and a corresponding increase in the redox indices v v ni and v cr the synchronous increase in 13c values and redox indices suggests that burial rates of marine organic carbon increased in response to the development of anoxic conditions in the water column an increase in 13c values in carbonate rocks across the cnb has also been reported from upper triassic sections in the western tethys e g in the pizzo mondello section sicily which suggests that the development of anoxic conditions within the cnb interval was widespread affecting both the panthalassan ocean and tethyan sea the geochemical data from this study as well as from research into conodont biostratigraphy in the black bear ridge section show that the onset of oceanic anoxic conditions may have been responsible for the faunal turnover event at the cnb the cause of this anoxic event is unknown but the 87sr 86sr and 13c isotope data largely exclude the possibility that the event was triggered by dissociation of methane hydrates and degassing related to large scale volcanic activity

impact of borehole depths on reconstructed estimates of ground surface temperature histories and energy storage estimates of ground surface temperature changes and continental energy storage from geothermal data have become well accepted indicators of climatic changes these estimates are independent contributions to the ensemble of paleoclimatic reconstructions and have been used for the validation of general circulation models and as a component of the energy budget accounting of the global climate system recent global and hemispheric analyses of geothermal data were based on data available in the borehole paleoclimatology database which contains subsurface temperature profiles from a minimum depth of 200 m to about 600 m because of the nature of heat conduction different depth ranges contain the record of past and persistent changes in the energy balance between the lower atmosphere and the ground for different time periods here we examine the dependency of estimated ground surface temperature histories and the magnitude of the subsurface heat content on the depth of borehole temperature profiles our results show that uncertainties in the estimates of the long term surface temperature are in the range of 0 5k we conclude that previous estimates of ground surface temperature change remain valid for the period since industrialization but longer term estimates are subject to considerable uncertainties the subsurface heat content shows a larger range of variability arising from differences in depth of the borehole temperature profiles as well as from differences in the time of data acquisition spanning four decades these results indicate that estimates of subsurface heat should be carried out with caution to decrease cumulative errors in any spatial analysis

strontium isotope 87sr 86sr stratigraphy of ordovician bulk carbonate implications for preservation of primary seawater values the present study on bulk carbonate 87 sr 86 sr stratigraphy represents a companion work to earlier research that presented a conodont apatite based ordovician seawater 87 sr 86 sr curve for the tremadocian katian stages 485 445 ma here we directly compare the curve based on conodont apatite including some new data not published in earlier work with a new curve based on 87 sr 86 sr results from bulk carbonate from the tremadocian sandbian stages we sampled eight lower to upper ordovician carbonate successions in north america to assess the reliability of bulk carbonate to preserve seawater 87 sr 86 sr and its utility for 87 sr 86 sr chemostratigraphy a high resolution 87 sr 86 sr curve based on 137 measurements of bulk conodont apatite is used as a proxy for seawater 87 sr 86 sr 87 sr 86 sr seawater in total 230 bulk carbonate samples that are paired to conodont samples were measured for 87 sr 86 sr in order to determine the conditions under which 87 sr 86 sr seawater is preserved in bulk carbonate results indicate that well preserved bulk carbonate can faithfully record the 87 sr 86 sr seawater trend but that its 87 sr 86 sr values are commonly more variable than those of conodont apatite on average bulk carbonate samples of the same age vary by 10 20 10 5 compared to 5 10 10 5 for conodont apatite the amount of isotopic alteration of bulk carbonate from seawater 87 sr 86 sr 87 sr 86 sr was determined by taking the difference between 87 sr 86 sr values of bulk carbonate and the approximated seawater trend based on the least radiogenic conodont 87 sr 86 sr values cross plots comparing 87 sr 86 sr values to bulk carbonate sr concentration sr and conodont color alteration indices cai an estimate of the thermal history of a rock body indicate that bulk carbonate is most likely to preserve 87 sr 86 sr seawater minimally altered when either 1 bulk carbonate sr is greater than 300 ppm or 2 carbonate rocks experienced minimal thermal alteration with burial temperatures less than 150 c carbonates with intermediate sr e g between 130 and 300 ppm can also yield 87 sr 86 sr seawater values but results are less predictable and local diagenetic conditions may play a greater role modeling results support the argument that seawater 87 sr 86 sr can be preserved in bulk carbonates with low sr if pore water rock ratios are low 87 sr 86 sr is similar to the seawater 87 sr 86 sr value preserved in limestone bulk carbonate samples that meet these criteria can be useful for high resolution measurements of 87 sr 86 sr seawater with a sample variation on par with fossil materials 5 particularly for successions where well preserved fossil material i e conodonts or brachiopods is not available such as precambrian strata sequences recording mass extinction events or otherwise fossil barren facies these criteria and model predictions based on bulk carbonate sr must be considered in the context of whether a limestone accumulated under calcite seas e g ordovician with relatively high seawater sr ca or aragonite seas in which case the diagenetic transformation of aragonite to calcite may result in incorporation of non seawater sr

ground warming patterns in the northern hemisphere during the last five centuries abstract changes in the earth s surface energy balance recorded underground were used to reconstruct the temperature of the ground surface for the last 500 years in the northern hemisphere we reconstructed ground surface temperature histories gsths from temperature versus depth profiles measured at 558 sites distributed between 30 and 60 n in the northern hemisphere we show that the ground has warmed about 0 5 k in the last 100 years spatial analysis reveals that spatial variability is important and that the weighted average northern hemisphere gsth shows some consistency with multiproxy and meteorological records reconstructions for the last two centuries

comparative fe and sr isotope study of nephrite deposits hosted in dolomitic marbles and serpentinites from the sudetes sw poland implications for fe as au bearing skarn formation and post obduction evolution of the oceanic lithosphere abstract nephrites belonging to both the dolomite related and serpentinite related genetic types from the zloty stok deposit and jordanow l ski and naslawice prospects in the leza ophiolite respectively were analyzed for fe and sr isotope compositions these deposits in the central sudetes sw poland are unusually situated relatively close to each other this study is a first attempt to perform combined fe and sr isotope study of nephrites our results show that fe in the fe as au bearing skarn samples from zloty stok 2 77 7 00 wt fe 56fe 0 07 to 0 14 and 57fe 0 12 to 0 21 to which the dolomite related nephrite belongs is not inherited from the host dolomitic marbles ca 0 4 wt fe 56fe 0 08 to 0 07 and 57fe 0 12 to 0 09 but derived from the nearby ca 340 ma granite intrusion 2 64 5 64 wt fe in contrast iron in the serpentinite related nephrites 2 06 3 88 wt fe 56fe 0 41 to 0 45 and 57fe 0 59 to 0 66 was likely inherited from host serpentinites 5 27 4 81 wt fe rather than metasomatically derived from adjacent granite intrusions 0 13 0 45 wt fe moreover both the marble transformation into a dolomite related nephrite and fe as au bearing skarn and the abyssal serpentinite through ophiolite towards serpentinite related nephrite transformation are accompanied by a progressive increase of 56fe and 57fe this increase is regardless of changes in the bulk fe content increasing during the dolomite related nephrite formation and decreasing during serpentinite related nephrite formation this phenomena may be caused by one of the below listed factors or combinations a preferential incorporation of heavy iron by tremolite and diopside b preferential incorporation of the heavy iron in the fe3 bearing phases crystallizing during nephrite formation c preferential incorporation of the heavy fe from migrating granite derived fluids positive fractionation between aqueous fe bearing fluid and tremolite diopside d positive isotope fractionation between dolomite antigorite precursor and newly formed amphibole clinopyroxene e change of the fe oxidation state furthermore fe in the rock forming tremolite from the serpentinite related nephrites is isotopically heavier than fe in tremolite from the dolomite related ones in contrast to the iron the isotopic composition of strontium combined with its content and structural evidence suggest multiple sources for this element in the case of the dolomite related nephrite ca 3 4 ppm sr initial 87sr 86sr 0 7085 sr inheritance from the host dolomitic marble ca 90 ppm sr initial 87sr 86sr 0 7081 as well as its derivation from intrusions of both the syn to late tectonic ca 340 ma granites ca 400 440 ppm sr and post tectonic 305 ma granites 86 4 ppm sr is suggested in the case of the serpentinite related nephrite 6 3 61 7 ppm sr initial 87sr 86sr 0 7037 to 0 7081 the situation is similar i e sr in the most primitive samples tends to be sourced from ophiolitic rocks up to 2 4 ppm sr in serpentinite whereas in the more evolved types it was likely delivered from the adjacent ca 340 ma 8 8 102 6 ppm sr partially rodingitized granites as well as 305 ma granites ca 80 ppm sr moreover these granites caused the fluid flow responsible for sr bearing clinozoisite vein formation these veins are likely related with nephrite formation and with a metallic mineralization

age determination of nephrite by in situ sims u pb dating syngenetic titanite a case study of the nephrite deposit from luanchuan henan china abstract nephrite is a kind of valuable jade which forms during metamorphism under greenschist facies conditions most investigations focus on the genesis of nephrite however the formation age of nephrite remains poorly constrained due to the lack of suitable dating methods in this paper the petrological chemical characteristics and mineral inclusions of nephrite collected from luanchuan henan china have been studied by optical and electron microscopy and wavelength dispersive electron microprobe emp the petrological observations show that nephrite consists mainly of tremolite minor calcite and titanite occasionally with rutile quartz serpentine chlorite pyrite and apatite the titanite and tremolite which are intergrown with each other share low energy grain boundaries it indicates that the two phases are equilibrated and can be considered as cogenetic the chemical composition of tremolite is high in si mg ca but low in fe cr and ni which indicates that the nephrite from luanchuan belongs to the dolomite type rather than the serpentinite type the petrography of different nephrite structures suggests that the grain size of tremolite was determined by the stress intensity undergone during the nephrite formation progress in situ secondary ion mass spectrometer sims u pb dating of titanite from nephrite yielded an age of 361 4 ma which is the first estimate for the time of formation of the luanchuan nephrite deposit this investigation provides a powerful in situ dating method to unravel the age of nephrite which could be served as a tool for future research on other nephrite deposits

u pb calcite age of the late permian castile formation delaware basin a constraint on the age of the permian triassic boundary reply to a comment by ian metcalfe

oxygen and strontium isotopes from fossil shark teeth environmental and ecological implications for late palaeozoic european basins article i nfo fossil shark remains occur in both marine and nonmarine late palaeozoic deposits therefore their palaeo ecology is controversial the oxygen and strontium isotopic composition of biogenic fluorapatite in 179 teeth scales and spines predominantly of hybodontid lissodus and xenacanthiform orthacanthus xenacanthus bohemiacanthus triodus sharks from various late carboniferous moscovian to early permian artinskian basins of europe are used as ecological tracers to decipher diadromous or obligate freshwater lifestyle of the investigated taxa the 18 op values of the different shark teeth range from 11 7 to 20 2 within the different basins with mean values of 16 9 0 5 for the bohemian massif 16 2 0 8 for eastern germany 18 2 1 0 for southwestern germany 18 5 0 7 for southern central spain 17 6 0 4 for