x ray microanalysis of fluid inclusions and its application to the geochemical modeling of evaporite basins direct access to brines trapped in halite is possible by freezing and breaking halite crystals on a cooling stage inside a scanning electron microscope quantitative analyses of major solutes na mg k ca cl and so4 in natural brines were obtained by means of x ray microanalysis of the frozen fluid inclusions using frozen droplets of brines with known composition as standards precision errors were estimated to be lower than 10 and detection limits vary from below 0 02 mol l for ca k and so4 to 0 55 mol l for na analyses of several inclusions of sizes larger than 20 m were performed for each cross section of halite the composition of primary fluid inclusions in halites from a drill core in the messinian basin of lorca se spain were used to constrain the parameters of a geochemical model of the evolution of the basin a computer program to simulate evaporation paths was developed using thermodynamic equilibrium and mass balance as constraints the halite sequence was interpreted as resulting from the evaporation of initial seawater in a hydrologically open basin with seawater replacing the evaporated water and a small fraction of basinal brine leaking out in the middle of the sampled sequence the basin was closed to the sea and only continental water flowed into the basin reworking part of the halite deposited in the margins in contrast with these results only very poor information would have been obtained from the mineralogical record alone consisting mainly of halite and minor gypsum

stable chlorine isotopes in the palo duro basin texas evidence for preservation of permian evaporite brines experimental evaporation of seawater yields brines with 37cl from 0 0 initial to 0 9 in the palo duro basin brines with 37cl values overlapping the 0 1 to 0 4 range of halite evaporite can be generated by a set of processes including dissolution of halite in meteoric water such brines occur above and below an evaporite aquitard brines with 37cl values of 0 4 to 1 0 in the evaporite aquitard and in a deep brine aquifer cannot be generated by dissolution of halite considered with br and cl content d and noble gas content the 37cl data indicate that such brines originated as evapoconcentrated seawater high br evaporite brine formed directly from seawater on the eastern side of the basin whereas low br evaporite brines on the western side formed after an influx of meteoric water at the time of evaporite formation there has not been detectable vertical flow of meteoric water across the evaporite aquitard strata beneath the evaporite contain compartments that have been isolated geochemically since the permian

δ2h of water from fluid inclusions in proterozoic halite evidence for a deuterium depleted hydrosphere abstract 2h were measured in water present in tiny primary fluid inclusions trapped in mesoproterozoic 1 4 ga and neoproterozoic 0 8 ga halite crystals while the hydrogen concentrations range from 300 to 1500 ppm for the whole sample collection 2h values range from 74 to 54 vsmow for the mesoproterozoic halite sampled from the sibley group ontario canada and from 89 to 38 for the neoproterozoic halite from the browne formation officer basin australia the amount of evaporation required to precipitate halite is accompanied by a deuterium enrichment of 30 to 90 it means that the original aqueous solutions had 2h values comprised between 140 and 90 considering the estimated tropical paleolatitudes for both depositional environments surface waters were most likely significantly deuterium depleted relative to modern ones if such interpretation is partly at variance with the geological record it could be reconciliated with some modelling outputs of the long term water cycle indeed several mechanisms produce a progressive deuterium enrichment of the oceans those identified so far are the addition of deuterium rich extraterrestrial water cometary dust the loss of h during water photodissociation by ultraviolet radiation in the upper atmosphere and the isotopic fractionation that takes place during the hydroxylation of nominally anhydrous mantle rock forming minerals we also propose that the major process able to shift through time the 2 of the hydrosphere is the reduction of h2o into h2 during the serpentinization of mantle rocks at mid ocean ridges

chronology and petrogenesis of a 1 8 g lunar granitic clast 14321 1062 abstract a study was undertaken to determine the chronology of a pristine granite clast 1062 from apollo 14 breccia 14321 using rb sr sm nd and 39ar 40ar methods the genesis of the granite as constrained by the isotopic results and trace element characteristics is discussed chronology the rb sr internal isochron is slightly disturbed and yields an age of 4 09 0 11 ae 87 rb 0 0139 ae 1 and an imprecise initial i sr 0 702 008 if two data are excluded the age becomes 4 13 0 03 ae and i sr 0 698 003 the whole rock and mineral separates are extremely radiogenic they yield model ages which are relatively well defined the average model age is 4 12 0 03 ae relative to babi 0 69898 the sm nd internal isochron is also slightly disturbed and gives an age of 4 11 0 20 ae 147 sm 0 00654 ae 1 the 39ar 40ar average age of the non magnetic fraction of the sample yields a slightly younger age of 3 88 0 03 ae k ar constants from steiger and a 1977 the concordancy of rb sr and sm nd internal isochrons with the rb sr model age strongly suggests that the granitic clast formed at 4 1 ae ago in the shallow crust and was later excavated and brecciated about 3 88 ae ago petrogenesis isotopic and trace element data of the lunar granite show large k la and rb sr fractionations small sm nd fractionation and the distinct v shaped ree distribution pattern at the time of crystallization a two stage model involving crystal fractionation followed by silicate liquid immiscibility sli is proposed for lunar granite genesis we propose that the granite can be the immiscible acidic liquid produced by sli from a residual liquid which underwent fractionation of ca 3 of phases with ree distribution coefficients similar to those of phosphate minerals from a highly evolved parental magma with ree contents about twice those of the 15405 85 quartz monzodiorite qmd the extreme scarcity of lunar granitic samples and their young formation ages suggest that they are probably not directly crystallized from the differentiation of the primordial magma ocean our isotopic results and trace elements data from other workers suggest that granites qmd and probably mggabbronorites may be genetically related and may have formed in a plutonic environment similar to gabbro granophyre associations in terrestrial layered intrusions such as the skaergaard intrusions

the record of temperature wind velocity and air humidity in the δd and δ18o of water inclusions in synthetic and messinian halites abstract deuterium and oxygen isotope fractionations between liquid and vapor water were experimentally determined during evaporation of a nacl solution 35 g l 1 as a function of water temperature and wind velocity in the case of a null wind velocity slopes of d 18o trajectories of residual waters hyperbolically decrease with increasing water temperatures in the range 23 47 c for wind velocities ranging from 0 8 to 2 2 m s 1 slopes of the d 18o trajectories linearly increase with increasing wind velocity at a given water temperature these experimental results can be modeled by using rayleigh distillation equations taking into account wind related kinetics effects deuterium and oxygen isotope compositions of water inclusions trapped by the precipitated halite crystals were determined by micro equilibration techniques these isotopic compositions accurately reflect those of the surrounding residual waters during halite growth isotopic compositions of water inclusions in twenty natural halites from the messinian realmonte mine in sicily suggest precipitation temperatures of 34 4 10 c that match the homogenization temperatures obtained by microthermometry median 34 5 c the similarity between the measured and experimental slopes of the d 18o evaporation trajectories suggests that the effect of wind was negligible during the genesis of these halite deposits hydrogen and oxygen isotope compositions of water inclusions from realmonte halite also define a linear trend whose extrapolation until intersection with the mediterranean meteoric water line allows the characterization of the water source with d and 18o values of 70 10 and 11 5 1 5 respectively these results reveal that the huge amounts of salts deposited in sicily result from the evaporation of seawater mixed with a dominant fraction 50 of meteoric waters most likely deriving from alpine fluvial discharge

atmospheric gas in modern and ancient halite fluid inclusions a screening protocol abstract halite possesses great potential for hosting and storing information vital to the reconstruction of earth s ancient climate seawater chemistry and evolving atmosphere here we propose a screening protocol that not only distinguishes between primary and secondary halite but also identifies fluid inclusions that carry original gas trapped during the primary crystallization process an integrated multi analytical protocol is presented for sample preparation petrographic evaluation analytical measurements and distinguishing original gases and contents from contaminants the screening protocol starts with the visual inspection of halite for primary chevron and hopper features and or milky appearance then petrography is used to distinguish between primary and secondary diagenetic crystal fabrics and inclusions the trace element and isotope geochemistry speak directly to the composition of the depositional and or diagenetic fluids and to the formation in marine non marine or diagenetic settings furthermore rare earth elements and redox sensitive elements may address the redox conditions of the salt pan flat brines whereas microthermometry helps characterize the depositional diagenetic environment s temperature finally gas extracted by quadrupole mass spectrometer from gas bubbles in fluid inclusions is screened with concomitant ch4 co2 and ar contents to distinguish and quantify organic matter decomposition contributions and with 40ar 36ar to monitor modern atmospheric gas diffusion leakage issues and thus contamination of the primary gas contents our test case shows that halite collected from cores is well suited in maintaining its original mineralogical texture chemistry and gas content our integrated screening protocol suggests that the 815 myr old halite from the tonian browne formation of the officer basin australia formed under atmospheric conditions of about 10 9 po2 back calculation or 9 6 po2 mean calculation the coeval neoproterozoic gypsum collected in outcrop from minto inlet victoria island canada underwent some mineralogical alteration however experiments suggest that depositional gypsum from outcrop core may have potential of retaining vestiges of original gas in fluid inclusions

the impacts of land plant evolution on earth s climate and oxygenation state an interdisciplinary review abstract the paleozoic emergence of terrestrial plants has been linked to a stepwise increase in earth s o2 levels and a cooling of earth s climate by drawdown of atmospheric co2 vegetation affects the earth s o2 and co2 levels in multiple ways including preferential organic carbon preservation by decay resistant biopolymers e g lignin and changing the continental weathering regime that governs oceanic nutrient supply and marine biological production over shorter time scales 1 myr land plant evolution is hypothesized to have occasionally enhanced p weathering and fertilized the oceans expanding marine anoxia and causing marine extinctions oceanic anoxia would eventually become limited by oceanic o2 uptake as oxygen accumulates in the atmosphere and surface oceans when excess organic carbon is buried in marine sediments here we review hypotheses and evidence for how the evolving terrestrial ecosystems impacted atmospheric and oceanic o2 and co2 from the ordovician and into the carboniferous 485 298 9 ma five major ecological stages in the terrestrial realm occurred during the prolonged time interval when land was colonized by plants animals and fungi marked by the evolution of 1 non vascular plants 2 vascular plants with lignified tissue 3 plants with shallow roots 4 arborescent and perennial vegetation with deep and complex root systems and 5 seed plants the prediction that land vegetation profoundly impacted the earth system is justified although it is still debated how the individual transitions affected the earth s o2 and co2 levels the geological record preserves multiple lines of indirect evidence for environmental transitions that can help us to reconstruct and quantify global controls on earth s oxygenation and climate state

the composition of gases in fluid inclusions of late permian zechstein marine evaporites in northern germany abstract in order to understand the generation of gases in late permian marine evaporites and the migration of gases in salt domes 428 gas bearing fluid inclusions of the gorleben salt dome northern germany were analysed using laser raman spectrometry lrs the investigations were divided in two parts in the first part only gas rich inclusions were analysed involving samples from different stratigraphic layers of the zechstein 2 stasfurt serie and zechstein 3 leine serie and from different locations within the salt dome for the second part only the gaseous components in brines rich inclusions of the zechstein 2 were measured the compositional range of all inclusions investigated can be subdivided into two main groups with rare exceptions the first group of n 2 and n 2 o 2 inclusions reveals a n 2 o 2 ratios close to that of modern atmosphere thus indicating trapped paleoatmosphere the second group is represented by inclusions that contain mixtures of n 2 ch 4 occasionally h 2 and or h 2 s the most abundant subgroups are n 2 ch 4 and n 2 ch 4 h 2 mixtures these gas mixtures can be produced by the decomposition of organic material under anoxic conditions it is noted that n 2 in both main groups can also be generated by degassing of underlying early permian rotliegendes or carboniferous c org rich sedimentary rocks and an entrapment in early stages of the zechstein halokinesis the different origin of both main groups is supported by stratigraphic correlation in the stratigraphic layers which contain mainly mixtures of n 2 and o 2 or pure n 2 inclusions of the n 2 ch 4 h 2 h 2 s group are rare and vice versa layers which are rich in n 2 ch 4 h 2 h 2 s do not contain many n 2 o 2 inclusions the majority of layers investigated frequently contains inclusions of the n 2 o 2 group only two anhydrite rich layers of zechstein 3 main anhydrite and anhydrite intercalated salt contain mainly inclusions of the second group the zechstein 3 potash seam as well as secondary halites contain more or less the same population of inclusions from every main group a comparison of the gas rich inclusions and the gases in the brine rich inclusions of the zechstein 2 layer main rock salt 3 shows distinct differences whereas the gas rich inclusions are of the n 2 o 2 group the gases from the brine rich inclusions are of the n 2 ch 4 group emphasising different origins the latter is a product of anhydrite rich parts or potash seams that have migrated later into the overlying main rock salt 3

impact melting of lunar meteorite dhofar 458 evidence from polycrystalline texture and decomposition of zircon abstract dhofar 458 is a lunar meteorite consisting mainly of olivine plagioclase intergrowths pyroxene plagioclase intergrowths and plagioclase fragments pyroxene plagioclase globules are also common in this study we report the discovery of a polycrystalline zircon in this lunar meteorite the polycrystalline zircon contains small vesicles and rounded baddeleyite grains at its margin the polycrystalline and porous texture of the zircon indicates high pressure shock induced melting and degassing baddeleyite grains are derived from decomposition of zircon under high postshock temperature the shock features in zircon indicates that the shock pressure in dhofar 458 was greater than approximately 60 gpa and the postshock temperature greater than approximately 1700 c the polycrystalline and degassing texture and decomposition zircon also strongly indicates that dhofar 458 is a clast rich impact melt rock during this shock event most components were melted and grains of mafic minerals are interstitial to lath like plagioclase grains large fragments of olivine and chromite also formed polycrystalline texture at margins and chemically reequilibrated with surrounding melts we suggest that pyroxene plagioclase globules could be remains of melted target clasts whereas vesicles may form during shock induced degassing of the rock the u pb isotopic data plot on a well defined discordant line yielding the age of the zircon of 3434 15 ma 2 this age is interpreted as the time of the impact event that melted dhofar 458 and caused decomposition and recrystallization of this zircon in dhofar 458 which reset this zircon s u pb age

sims u pb study of zircon from apollo 14 and 17 breccias implications for the evolution of lunar kreep abstract we report the results of a sims u pb study of 112 zircons from breccia samples from the apollo 14 and 17 landing sites zircon occurs in the breccia matrices as rounded irregular shaped broken and rarely euhedral grains and as constituent minerals in a variety of lithic clasts ranging in composition from ultra mafic and mafic rocks to highly evolved granophyres crystallisation of zircon in magmatic rocks is governed by the zirconium saturation in the melt as a consequence the presence of zircon in mafic rocks on the moon implies enrichment of their parent melts in the kreep component our sims results show that the ages of zircons from mafic to ultramafic clasts range from ca 4 35 ga to ca 4 00 ga demonstrating multiple generations of kreepy mafic and ultramafic magmas over this time period individual zircon clasts in breccia matrices have a similar age range to zircons in igneous clasts and all represent zircons that have been incorporated into the breccia from older parents the age distributions of zircons from breccias from both the apollo 14 and apollo 17 landing sites are essentially identical in the range 4 35 4 20 ga however whereas apollo 14 zircons additionally show ages from 4 20 to 3 90 ga no zircons from apollo 17 samples have primary ages less than ca 4 20 ga also in contrast to previous suggestions that the magmatism in the lunar crust is continuous our results show that the zircon age distribution is uneven with distinct peaks of magmatic activity at ca 4 35 ga ca 4 20 ga in apollo 14 and 17 and a possible third peak in zircons from apollo 14 at ca 4 00 ga to explain the differences in the zircon age distributions between the apollo 14 and 17 landing sites we propose that episodes of kreep magmatism were generated from a primary reservoir and that this reservoir contracted over time towards the centre of procellarum kreep terrane we attribute the peaks in kreep magmatism to impact induced emplacement of kreep magma from a primary mantle source or to a progressive thermal build up in the mantle source until the temperature exceeds the threshold for generation of kreep magma which is transported into the crust by an unspecified possibly plume like process

geochemistry of modern brachiopods applications and implications for oceanography and paleoceanography abstract modern rhynchonellida terebratulida thecideida and a few inarticulated brachiopods were collected live or soon after death at 30 locations from depths of 2 3940 m from the equator to high latitudes covering the atlantic pacific indian caribbean and mediterranean oceans seas well preserved fibers of the secondary layer combined with sr 450 1928 mg kg mn 1 199 mg kg and fe 1 610 mg kg contents confirm with few exceptions the excellent preservation of the modern brachiopod material evaluation of the stable isotope compositions was conducted on 276 specimens and on 374 published samples for a total database of 650 samples from 80 locations it revealed that oxygen isotope incorporation into shell calcite secondary layer of modern articulated brachiopods in most cases occurs in equilibrium with the ambient water and as such reflects surrounding environmental conditions thecideida as a group shallow water and low latitude incorporate oxygen isotopes 3 04 to 0 35 into shell calcite in equilibrium with their ambient water a large majority of genera and species of the terebratulida shallow water and low mid latitude also incorporate oxygen 2 30 to 3 48 into shell calcite in isotopic equilibrium with their surrounding water in contrast equilibrium incorporation of oxygen isotopes into shell calcite by the rhynchonellida is uncertain but a vital effect probably applies to the craniida the question of equilibrium disequilibrium incorporation of carbon isotopes into shell calcite of modern brachiopods remains unresolved at this time isotope compositions range up to 4 5 5 6 and 1 5 for 13 c and up to 5 5 5 9 and 0 3 for 18 o for shallow water low mid and high latitude brachiopods respectively strontium isotopes of modern brachiopods as expected show no significant variation with location latitude water depth temperature salinity and general water conditions once local habitat and ecological influences of fossil brachiopods from similar latitudes are considered their isotopic elemental values should be valuable diagenetic indicators and important oceanographic chemostratigraphic proxies

analyses of fluid inclusions in neoproterozoic marine halite provide oldest measurement of seawater chemistry we analyzed primary fluid inclusions in halite from marine evaporites in the ca 830 ma browne formation of the officer basin in western australia using the cryogenic scanning electron microscopy energy dispersive x ray spectrometry analysis technique the concentrations of the major ions except k and possibly so 4 2 fall within the range of phanerozoic seawater this is the first direct measurement of the composition of mid neoproterozoic seawater and extends present day knowledge of seawater chemistry by 300 m y our estimates suggest that mid neoproterozoic marine sulfate concentrations were lower 90 than modern values by the terminal neoproterozoic fluid inclusions in halite and evaporite mineralogy indicate seawater sulfate levels rose significantly to 50 80 of modern concentrations which parallels increases in atmospheric and oceanic oxygen

gas bubbles in fossil amber as possible indicators of the major gas composition of ancient air gases trapped in miocene to upper cretaceous amber were released by gently crushing the amber under vacuum and were analyzed by quadrupole mass spectrometry after discounting the possibility that the major gases n2 o2 and co2 underwent appreciable diffusion and diagenetic exchange with their surroundings or reaction with the amber it has been concluded that in primary bubbles gas released during initial breakage these gases represent mainly original ancient air modified by the aerobic respiration of microorganisms values of n2 co2 o2 for each time period give consistent results despite varying o2 co2 ratios that presumably were due to varying degrees of respiration this allows calculation of original oxygen concentrations which on the basis of these preliminary results appear to have changed from greater than 30 percent o2 during one part of the late cretaceous between 75 and 95 million years ago to 21 percent during the eocene oligocene and for present day samples with possibly lower values during the oligocene early miocene variable o2 levels over time in general confirm theoretical isotope mass balance calculations and suggest that the atmosphere has evolved over phanerozoic time

fluid inclusion gas compositions from an active magmatic hydrothermal system a case study of the geysers geothermal field usa abstract hydrothermal alteration and the active vapor dominated geothermal system at the geysers ca are related to a composite hypabyssal granitic pluton emplaced beneath the field 1 1 to 1 2 million years ago deep drill holes provide a complete transect across the thermal system and samples of the modern day steam the hydrothermal system was liquid dominated prior to formation of the modern vapor dominated regime at 0 25 to 0 28 ma maximum temperatures and salinities ranged from 440 c and 44 wt nacl equivalent in the biotite hornfels adjacent to the pluton to 305 c and 5 wt nacl equivalent at distances of 1730 m from the intrusive contact the major minor and noble gas compositions of fluid inclusions in the hydrothermally altered rocks were integrated with microthermometric and mineralogic data to determine their sources and the effects of mixing and boiling major and minor gaseous species were released from the inclusions by crushing or thermal decrepitation noble gases were released by crushing the samples were analyzed by mass spectrometry the analyses document the presence of magmatic crustal and meteoric components in the trapped fluids hydrothermal fluids present during the liquid dominated phase of the system contained gaseous species derived mainly from crustal and magmatic sources at the geysers n 2 ar ratios greater than 525 and 3 he 4 he ratios of 6 10 7 ra are diagnostic of a magmatic component crustal gas has co 2 ch 4 ratios less than 4 n 2 ar ratios between 45 and 525 and low 3 he 4 he ratios 0 5 ra meteoric fluids have co 2 ch 4 ratios greater than 4 and n 2 ar ratios between 38 air saturated water and 84 air however n 2 ar ratios between 15 and 110 can result from boiling ratios less than 15 reflect the incorporation of n 2 into nh 3 bearing clay minerals in the central geysers the incursion of meteoric fluids occurred during the transition from the liquid to vapor dominated regime variations in the relative ch 4 co 2 and h 2 contents of the gas analyses demonstrate that boiling took place under open system conditions the gas data indicate that the inclusions have remained closed to the diffusion of he and h 2 since their formation

observations on the incorporation of trace elements in halite of oligocene salt beds bourg en bresse basin france abstract it is common practice to employ trace elements found in chloride salts as indicators of the conditions of deposition because some halite contains abundant fluid inclusions it is necessary to separate the salt from the inclusions before analysis this study presents the data derived from the use of a simple preparative technique which permits analysis of the trace elements in solid halite and provides a guide to test the success in elimination of the contaminants contained in the fluid inclusions the differentiation is accomplished simply by crushing the salt in alcohol followed by separate analysis of the fluid and solid components thus yielding accurate trace element concentrations in the solids crystal lattice dislocations and grain boundaries and the fluids br and k are present both in the solid and liquid phases of the halite but mg is exclusively in the fluid inclusions the elimination of the mg from the analysis of the solid phase may thus be employed as a monitor to indicate the degree of purification of the samples being analysed

criteria for the recognition of salt pan evaporites layered evaporites can accumulate in 1 ephemeral saline pans 2 shallow perennial lagoons or lakes and 3 deep perennial basins criteria for recognizing evaporites deposited in these settings have yet to be explicitly formulated the characteristics of the ephemeral saline pan setting have been determined by examining eight holocene halite dominated pans salt pans and their deposits marine and non marine from the u s mexico egypt and bolivia these salt pans are typified by alternating periods of flooding resulting in a temporary brackish lake evaporative concentration when the lake becomes saline and desiccation which produces a dry pan fed only by groundwater the resulting deposits consist of alternating layers millimetres to decimetres of halite and mud the layers of halite are characterized by 1 vertical and horizontal cavities rounded crystal edges and horizontal truncation surfaces due to dissolution during flooding 2 vertical chevrons and cornets grown syntaxially on the bottom during the saline lake stage 3 halite cements overgrowths and euhedral cavity linings and disruption of layering into metre scale polygons produced during the desiccation stage the muddy interbeds are characterized by displacive growth of halite during the desiccation stage immediately below the surface of the pan the halite layers are matured by repeated episodes of dissolution and diagenetic crystal growth this results in porous crusts with patches of chevron and cornet crystals truncated by dissolution clear diagenetic halite cement and internal sediment these layers of mature halite closely resemble the patchy cloudy and clear textures of ancient halite deposits holocene salt pans are known to cover thousands of square kilometres and cap halite deposits hundreds of metres thick so they are realistic models for ancient evaporites in scale e g permian salado formation of new mexico texas which preserves many primary salt pan features

drought reconstruction in eastern hulun buir steppe china and its linkages to the sea surface temperatures in the pacific ocean abstract a tree ring width chronology covering the period 1780 2013 ad was developed from pinus sylvestris var mongolica for the eastern hulun buir steppe a region located on the edge of the eastern mongolian plateau china climate growth response analysis revealed drought stress to be the primary limiting factor for tree growth therefore the mean february july standardized precipitation evapotranspiration index spei was reconstructed over the period 1819 2013 where the reconstruction could account for 32 8 of the variance in the instrumental record over the calibration period 1953 2011 comparison with other tree ring based moisture sequences from nearby areas confirmed a high degree of confidence in our reconstruction severe drought intervals since the late 1970s in our study area consisted with the weakening east asian summer monsoon which modulating regional moisture conditions in semi arid zone over northern china drought variations in the study area significantly correlated with sea surface temperatures ssts in north pacific ocean suggesting a possible connection of regional hydroclimatic variations to the pacific decadal oscillation pdo the potential influence associated with el nino southern oscillation enso was primarily analyzed

ediacaran seawater temperature evidence from inclusions of sinian halite abstract seawater temperatures throughout earth s history have been suggested to illustrate a long term cooling trend from nearly 70 c at 3500 ma to around 20 c at 800 ma the terminal neoproterozoic prior to the cambrian explosion is a key interval in evolutionary history as complex multicellularity appeared with the advent of the ediacara fauna these organisms were likely the first that required higher levels of atmospheric and dissolved marine oxygen for their sustainability it is known that most modern macroinvertebrates are intolerant of temperatures in excess of 45 c perhaps more importantly these high seawater temperatures limit the potential of dissolved oxygen and therefore become an integral part of this evolutionary story previously our understanding of seawater temperature during the terminal neoproterozoic comes only from 18 o 16 o and 30 si 28 si ratios ascertained from a limited number of cherts isotopic ratio methods for assessing seawater temperatures are inherently indirect and have a wide range of oscillation however maximum homogenization temperatures th max of primary fluid inclusions in halite provide a direct means of assessing brine temperature and have been shown to correlate well with average maximum air temperatures the oldest halites date to the neoproterozoic lower paleozoic 700 500 ma and ediacaran representatives can be found in sichuan province china which do preserve primary fluid inclusions for analysis via cooling nucleation methods we utilized halite samples from the changning 2 well correlative to the dengying formation 551 542 ma to provide a direct assessment of terminal neoproterozoic seawater temperature our measurements indicate that seawater temperatures where these halites formed are highly similar to tropical phanerozoic seawater temperature estimates from compiled paleotemperature data the decline in seawater temperatures over the course of the proterozoic accompanied by the reduction of seawater salinity with the sequestration of salt in massive halite deposits in the neoproterozoic allowed the ocean system to accumulate more dissolved oxygen and potentially paved the way for the evolutionary innovation of complex multicellularity

paradigm shift in determining neoproterozoic atmospheric oxygen acknowledgments we thank the geological survey of australia for permission to sample the empress 1a and lancer 1 cores the natural sciences and engineering research council of canada for financial support grant 7961 15 of u brand and the national natural science foundation of china for support of f meng and p ni grants 41473039 and 4151101015 we thank m lozon brock university for drafting and constructing the figures we thank the editor brendan murphy as well as three reviewers steve kesler erik sperling and an anonymous reviewer for improving the manuscript into its final form

the isotopic record of lunar volcanism abstract the timing and extent of lunar volcanism was determined primarily by the internal thermal evolution of the moon a late heavy bombardment produced most of the observable lunar basins easily recognized stratigraphic markers and also may have influenced lunar volcanism most of the nearside basins seem to have been produced 3 8 4 0 ga ago during a period often referred to as the lunar cataclysm the pre cataclysm period was characterized by formation of the lunar crust plutonic rocks within the crust and pre mare volcanism isotopic analysis of breccia clasts pre dating the cataclysm has yielded an outline of this period the isotopic record of post cataclysm mare volcanism is clear but incomplete because samples from the youngest mare areas are lacking specifically the isotopic data show that some lunar anorthosites formed 4 45 ga ago consistent with early formation of an anorthositic lunar crust some mg suite norites troctolites and dunites also formed approximately contemporaneously with the oldest anorthosites but others are up to 200 300 ma younger more evolved rocks granites and quartz monzodiorites also formed between 4 4 and 4 0 ga ago the earliest known pre mare volcanism at 4 25 ga ago included aluminous mare like basalts and an olivine gabbronorite similar to apollo 12 basalts kreep basalt volcanism began at least 4 1 ga ago approximately contemporaneously with that of the ancient mare like basalts and continued during the cataclysm recorded instances of high ti mare basalt volcanism began during or immediately after the cataclysm low ti mare basalt volcanism is the most recent for which samples are available the isotopic data record an early primary lunar differentiation during which mare basalt sources formed probably by crystallization of cumulus minerals from a lunar magma ocean the isotopic record of post cataclysm basalts indicates a heterogeneous lunar mantle and can be explained by partial melting of cumulate sources but more complex petrogenesis also has been suggested more complex petrogenetic processes including assimilation and assimilation fractional crystallization afc seem to be required for pre mare volcanics the isotopic data contain a hint that petrogenesis of the oldest pre mare volcanics may be linked to formation of the so called procellarum basin possibly the oldest and largest lunar basin such a basin would provide a geologic context for the pre mare volcanics and its formation may have been a defining moment in lunar history

precise determination of phanerozoic zircon pb pb age by multicollector sims without external standardization 1 zircon has long been recognized as the best geochronometer and the most important timekeeper in geosciences modern microbeam techniques such as sims and la icpms have been successfully applied to in situ u pb zircon age determinations at spatial resolutions of 20 30 m or less matrix matched calibration by external standardization of well characterized natural zircon references is a principal requirement for precise microbeam u pb zircon age determination due to fractionation effects between pb and u which usually result in an external age error exceeding 1 alternatively zircons with a closed u pb system can be directly dated by measurement of 207pb 206pb isotopic ratio without external standardization which has been a common practice for zircons older than 1 0 ga but not for relatively young 1 0 ga and particularly phanerozoic ones because of limitations of analytical precision we describe in this paper a method of 207pb 206pb measurement on phanerozoic zircons using a new generation of large radius magnetic sector multicollector cameca ims 1280 sims in combination with multicollector mode a nuclear magnetic resonance nmr magnet controller and oxygen flooding techniques we achieve precisions of 207pb 206pb ratio of 0 1 and 0 1 0 2 propagating to pb pb age errors 0 4 and 1 3 excluding u decay constant uncertainties for zircons of latest neoproterozoic and late paleozoic to mesozoic age respectively therefore the multicollector sims is capable of direct determination of zircon pb pb ages as young as mesozoic age with uncertainties of geological significance this technique is useful for direct dating of zircons in thin sections moreover it has significance for dating of some other u rich minerals i e baddeleyite and zirconolite that are not suitable for sims u pb dating by external standardization

carbon oxygen and strontium isotopes in paleozoic carbonate components an evaluation of original seawater chemistry proxies abstract brachiopods trilobites cements and whole rock matrix material were evaluated for their reliability as proxies of original seawater carbon oxygen and strontium isotope chemistry in this process coeval material was evaluated from individual horizons of formations spanning the permian to cambrian unaltered shells of low mg calcite articulated brachiopods retain original seawater oxygen carbon and strontium isotope compositions as old as late ordovician assessments of older specimens are hampered by a lack of suitable material coeval brachiopod whole rock sets a definitive assessment of cement marine chemistry is difficult due to the paucity of material but despite this caveat cements hold some promise for retaining original carbon and possibly strontium isotope seawater values in contrast the potential of whole rock material as a proxy of original seawater chemistry is quite complex in some but not all instances the carbon isotopic composition of whole rock after detailed scrutiny and evaluation appears to represent an original seawater chemistry signal in a few instances their oxygen isotope compositions reflect original seawater values unlike the stable isotope compositions the strontium isotopes of all studied whole rock material permian to upper cambrian appear not to reflect original seawater chemistry values thus the potential for retaining original seawater isotope chemistry and serving as specific proxies in order of decreasing reliability are 1 unaltered low mg calcite brachiopods c o and sr isotopes 2 pristine marine cements c and sr isotopes and 3 whole rock material c isotopes carbon oxygen and strontium isotope compositions of ordovician trilobites mirror those of coeval unaltered brachiopods cambrian trilobites hold significant promise as an important proxy of original seawater isotope chemistry but further studies are needed to ascertain their full potential the survey of isotopes in some ordovician and cambrian intermediate low mg calcite trilobites demonstrates their potential as an important proxy of original seawater chemistry

pb u and th diffusion in natural zircon zircon zrsio4 is one of the most widely used minerals for determining the age origin and thermal history of rocks by u th pb geochronology but the parameters describing the solid state volume diffusion rates of these elements in natural zircon which are themselves important for establishing the limits on the applicability of zircon for geochronological studies have remained poorly quantified1 this is because of the measurement difficulties associated with the low p p m concentrations and low diffusion rates of these elements in natural zircon and the chemical and physical heterogeneity present in most crystals here we present direct measurements of the uranium thorium and lead loss from a thermally treated gem quality natural zircon and show that lead diffuses much faster than uranium or thorium we find that the u th pb isotopic system in natural zircon will typically have a closure temperature greater than 900 c which explains why zircon is apparently such a robust geochrometer and is capable of remaining isotopically closed through extended periods of high grade metamorphism and partial melting of the host rock

composition of fluid inclusions in permian salt beds palo duro basin texas u s a abstract several methods have been developed and used to extract and chemically analyze the two major types of fluid inclusions in bedded salt from the palo duro basin texas data on the ratio k ca mg were obtained on a few of the clouds of tiny inclusions in chevron salt representing the brines from which the salt originally crystallized much more complete quantitative data na k ca mg sr cl so 4 and br were obtained on 120 individual large mostly 500 m on an edge i e 1 6 10 4 g inclusions in recrystallized salt these latter fluids have a wide range of compositions even in a given piece of core indicating that fluids of grossly different composition were present in these salt beds during the several stages of recrystallization the analytical results indicating very large inter and intra sample chemical variation verify the conclusion reached earlier from petrography and microthermometry that the inclusion fluids in salt and their solutes are generally polygenetic the diversity in composition stems from the combination of a variety of sources for the fluids permian sea meteoric and groundwater as well as later migrating ground formation or meteoric waters of unknown age and a variety of subsequent geochemical processes of dissolution precipitation and rock water interaction the compositional data are frequently ambiguous but do provide constraints and may eventually yield a coherent history of the events that produced these beds such an understanding of the past history of the evaporite sequence of the palo duro basin should help in predicting the future role of the fluids in the salt if a nuclear waste repository is sited there

pdsi variations at kongtong mountain china inferred from a 283 year pinus tabulaeformis ring width chronology 1 pinus tabulaeformis ring widths were used to reconstruct mean palmer drought severity indices pdsis from may to july for each of the past 283 years for kongtong mountain china a calibration model for the period from 1940 to 2005 explains 66 4 or 65 9 after adjusting for the loss of the degrees of freedom of the actual pdsi variance the reconstructed kongtong mountain pdsis could be representative of the moisture conditions of the entire loess plateau the reconstruction captures a severe 1927 1930 drought event that was widespread across all of northern china after 11 year moving average the reconstructed kongtong pdsi was found to compare well with other tree ring based temperature reconstructions from both huanglong in the eastern part of the chinese loess plateau and hokkaido japan this result indicates that high temperatures may be a major contributor to the severity of dryness at low frequencies significant 93 33 year and approximate 2 year cycles were observed in the kongtong tree ring chronology

a paleoweathering profile from griqualand west south africa evidence for a dramatic rise in atmospheric oxygen between 2 2 and 1 9 bybp a core drilled near wolhaarkop in griqualand west south africa intersected highly oxidized kuruman iron formation below red beds of the gamagara formation the lateral equivalents of the kuruman iron formation in this drill hole consist largely of siderite ankerite magnetite greenalite and quartz the oxidation of the kuruman iron formation in wol 2 occurred almost certainly during weathering prior to the deposition of the gamagara formation the date of this weathering episode is bracketed between about 2 2 and 1 9 bybp by the age of the ongeluk lavas in the transvaal sequence below the unconformity and by the age of the hartley lavas in the olifantshoek group above the unconformity the ratio of iron to sio2 in the several facies of the weathered kuruman iron formation in wol 2 is nearly the same as that in their unweathered equivalents since sio2 loss during weathering was almost certainly minor the similarity of the fe sio2 ratio in the weathered and unweathered bif indicates that nearly all the feo in the kuruman iron formation was oxidized and retained as feo3 during weathering such a high degree of iron retention is best explained by an o2 content of the atmosphere or 0 03 atm at the time of weathering such an o2 pressure is very much greater than that suggested by the composition of paleosols developed on basalt or 2 2 bybp but is consistent with the highly oxidized nature of the 1 85 by flin flon paleosol the new data suggest that po2 rose dramatically from about 1 percent pal present atmospheric level to or 15 percent pal between 2 2 and 1 9 bybp

geochemistry petrology and ages of the lunar meteorites kalahari 008 and 009 new constraints on early lunar evolution abstract kalahari 008 and 009 are two lunar meteorites that were found close to each other in botswana kalahari 008 is a typical lunar anorthositic breccia kalahari 009 a monomict breccia with basaltic composition and mineralogy based on minor and trace elements kalahari 009 is classified as vlt very low ti mare basalt with extremely low contents of incompatible elements including the ree the lu hf data define an age of 4286 95 ma indicating that kalahari 009 is one of the oldest known basalt samples from the moon it provides evidence for lunar basalt volcanism prior to 4 1 ga pre nectarian and may represent the first sample from a cryptomare the very radiogenic initial 176hf 177hf ehf 12 9 4 6 the low ree th and ti concentrations indicate that kalahari 009 formed from re melting of mantle material that had undergone strong incompatible trace element depletion early in lunar history this unusually depleted composition points toward a hitherto unsampled basalt source region for the lunar interior that may represent a new depleted endmember source for low ti mare basalt volcanism apparently the moon became chemically very heterogeneous at an early stage in its history and different cumulate sources are responsible for the diverse mare basalt types evidence that kalahari 008 and 009 may be paired includes the similar fayalite content of their olivine the identical initial hf isotope composition the exceptionally low exposure ages of both rocks and the fact that they were found close to each other since cryptomaria are covered by highland ejecta it is possible that these rocks are from the boundary area where basalt deposits are covered by highland ejecta the concentrations of cosmogenic radionuclides and trapped noble gases are unusually low in both rocks although kalahari 008 contains slightly higher concentrations a likely reason for this difference is that kalahari 008 is a polymict breccia containing a briefly exposed regolith while kalahari 009 is a monomict brecciated rock that may never have been at the surface of the moon altogether the compositions of kalahari 008 and 009 permit new insight into early lunar evolution as both meteorites sample lunar reservoirs hitherto unsampled by spacecraft missions the very low th and ree content of kalahari 009 as well as the depletion in sm and the lack of a kreep like signature in kalahari 008 point to a possible source far from the influence of the procellarum kreep terrane possibly the lunar farside

39ar 40ar dating of two lunar granites the age of copernicus previous investigations have suggested that kreep glass found in 12033 and other apollo 12 soils was ejected from the crater copernicus and deposited in a ray across this site soil fragment 12033 507 has been described as having a core of felsite granitic composition with a kreep glass shell 39ar 40ar dating of a sample of this granite material shows almost complete resetting 800 15 ma ago we interpret this age as giving the most precise determination to date for the formation time of copernicus cosmic ray exposure ages of the granite and associated kreep glass in soil 12033 about 250 ma are much less than the k ar age and suggest a complex postejection burial history the 39ar 40ar age of another granite fragment 14303 204 is determined to be in the range 3 80 3 85 ga this age is in agreement with 39ar 40ar ages determined for a few other lunar granites and is interpreted to represent resetting by a large basin forming impact probably imbrium

highly silicic compositions on the moon using data from the diviner lunar radiometer experiment we show that four regions of the moon previously described as red spots exhibit mid infrared spectra best explained by quartz silica rich glass or alkali feldspar these lithologies are consistent with evolved rocks similar to lunar granites in the apollo samples the spectral character of these spots is distinct from surrounding mare and highlands material and from regions composed of pure plagioclase feldspar the variety of landforms associated with the silicic spectral character suggests that both extrusive and intrusive silicic magmatism occurred on the moon basaltic underplating is the preferred mechanism for silicic magma generation leading to the formation of extrusive landforms this mechanism or silicate liquid immiscibility could lead to the formation of intrusive bodies

pb diffusion in zircon abstract chemical diffusion of ti under anhydrous conditions at 1 atm and under fluid present elevated pressure 1 1 1 2 gpa conditions has been measured in natural zircon the source of diffusant for 1 atm experiments was a zro2 tio2 zircon mixture with experiments run in crimped pt capsules diffusion experiments done in the presence of h2o co2 fluid were run in a piston cylinder apparatus using a source of ground tio2 zrsio4 and sio2 with oxalic acid added to produce h2o co2 vapor and partially melt the solid source material yielding an assemblage of rutile zircon melt vapor nuclear reaction analysis nra with the resonant nuclear reaction 48ti p 49v was used to measure diffusion profiles for both sets of experiments the following arrhenius parameters were obtained for ti diffusion normal to cover the temperature range 1350 1550 c at 1 atm d ti 3 33 10 2 exp 754 56 kj mol 1 r t m 2 s 1 ti diffusivities were found to be similar for experiments run under fluid present conditions a fit to all of the data yields the arrhenius relation d 1 34 102 exp 741 46 kj mol 1 rt m2 s 1 these data suggest that zircon should be extremely retentive of ti chemical signatures indicating that the recently developed ti in zircon crystallization geothermometer watson e b harrison t m 2005 zircon thermometer reveals minimum melting conditions on earliest earth science 308 841 844 will be quite robust in preserving temperatures of zircon crystallization titanium diffuses somewhat faster in zircon than larger tetravalent cations u th and hf but considerably more slowly than pb the ree and oxygen hence ti crystallization temperatures may be retained under circumstances when radiometric ages or other types of geochemical information are lost

chemostratigraphy of the shaler supergroup victoria island nw canada a record of ocean composition prior to the cryogenian glaciations a b s t r a c t a new 13 ccarb curve combined with 13 corg values is presented for the upper shaler supergroup 900 to 720 ma amundsen basin northwestern canada the dataset fills gaps in the existing stratigraphic record and makes correlations with adjacent basins more robust there is a pronounced negative 13 c excursion in the wynniatt formation that can be correlated with a putative worldwide negative car bon isotope excursion namely the bitter springs stage however in the amundsen basin the 13 ccarb excursion drops to anomalously negative values 14 which we attribute to local overprints wherein isotopically light carbon in pore waters released by oxidation of methane and organic matter during sulphate and iron reduction was incorporated into authigenic carbonate cement we document basin euxinia and anoxia during the same time interval using a multi proxy approach specifically fe speciation and redox sensitive trace metal data patterns of pronounced enrichment in mo v and u concentrations in euxinic black shales suggest that the bitter springs stage was a transitional period in earth s redox evo lution from the more reduced global oceans during the mid proterozoic to the more oxygenated oceans during the phanerozoic 2015 elsevier b v all rights reserved

tree ring derived temperature records in the central loess plateau china using tree ring widths of pinus tabulaeformis carr trees mean temperatures from february to september were reconstructed for the kongtong mountain during the past 283 years the reconstruction could explain 43 7 of temperature variance during the calibration period from 1951 to 2004 it displays similar patterns to several temperature reconstructions in the loess plateau it corresponds well with the temperature regimes in hokkaido japan indicating that both regions have similar warm and cold intervals the high correlation between the reconstruction and the cru climatic research unit of university of east anglia uk ts3 temperature datasets showed that the temperature reconstruction could be representative of large scale climate change over northern china in addition the pacific decadal oscillation pdo affected temperature variations of northern china and even hokkaido to a certain extent

thermal history of apollo 12 granite and kreep rich rock clues from pb pb ages of zircon in lunar breccia 12013 abstract with the mafic to ultramafic petrology of the moon the presence of granite appears anomalous however fragments of rocks with a definite granitic textures and mineralogy have been recovered from the maria where their ages point to an ultimate origin in the highlands apollo 12 mare breccia 12013 is one of these unique lunar rocks containing abundant granitic components it consists of a black portion composed mainly of fragments of plagioclase and noritic rock with minor fragments of granitic rock and a gray portion that is dominated by an overall granitic component zircon grains from this breccia were studied by combining cathodoluminescence cl imaging and micron scale ion microprobe dating techniques zircon grains from the black portion have a large age variation 4 0 4 3 ga a few of them exhibit complex age zoning within individual grains corresponding to cl zoning zircon grains from the gray portion show no cl zoning features but also have a large age variation between different grains 4 2 4 3 ga in this study we suggest that the large age variations of zircon in 12013 among different grains and within individual grains were caused by post crystallization impact events and most of them are not original crystallization ages the 4 3 ga zircon age probably represents the minimum crystallization age of the granitic component in 12013 similar to lunar granites from the apollo 14 and 17 landing sites this old crystallization age also implies that various ree patterns of lunar granites might not be entirely related to their crystallization ages based on comparison with the 207pb 206pb ages for zircon from the apollo 12 14 and 17 landing sites we suggest that there was at least one pre 3 9 ga major impact event on the moon at 4 2 ga

zircon saturation in lunar basalts and granites the saturation surface for zircon in late stage lunar basalts and granites has been determined over the temperature range1400 1070 c the saturation surface in the basalt shows a strong temperature dependence from 1400 to 1200 c below 1200 the saturation surface turns down sharply and becomes nearly temperature independent the saturation surface in the granitic composition is similar to the basaltic composition although less zr is required for saturation at 1100 c 9000 ppm zr and 5000 ppm zr are required for zircon saturation in the basalt and granite respectively if a magma with chondritic zr content is assumed then zircon saturation would not be reached until 99 96 99 92 crystallization this precludes zircon crystallization playing a major role in the trace element evolution of lunar magmas

tree ring based drought reconstruction at the northwestern margin of monsoon region of china since 1862 a tree ring width chronology developed from three sites of pinus tabulaeformis at the northwestern margin of the monsoon region of china was employed to study regional drought variability the drought reconstruction spanning 1862 2007 was developed by calibrating tree ring data with the palmer drought severity index pdsi an index indicating regional moisture conditions the reconstruction accounted for 43 3 of actual pdsi variance during their common period 1948 2005 droughts lasting over four years were found in 1877 1885 1889 1893 1925 1932 and 2004 2007 among which the droughts epochs in 1877 1885 and 1925 1932 were the two most severe and long lasting in the study area since 1862 there was an aridity aggravation trend since the mid 1970s in the reconstructed series which was consistent with the global temperature rise in records since 1975 this study indicated the feasibility of combining tree rings and the pdsi to reconstruct large scale drought patterns over this area and the pdsi reconstructed by tree ring may be a good proxy for the adjacent desert evolution

tree ring based drought reconstruction for the central tien shan area in northwest china 1 a robust ring width chronology developed from two sites of picea schrenkiana in the central tien shan area of northwest china was employed to study regional drought variability our analyses demonstrate both temperature and precipitation have significant effects on tree growth thus both should be considered for climate reconstruction regional drought history 1675 2002 a d was therefore reconstructed by calibrating with the palmer drought severity index pdsi our reconstruction not only captured well those extreme drought events recorded in local historical archives but also revealed the long term pattern of drought variability especially the trend of increasing moisture during the 20th century multi taper method spectral analysis indicates the existence of some low and high frequency cycles 146 171 11 5 10 6 9 7 6 1 3 9 3 4 3 2 2 4 and 2 1 yr overall our study indicates the feasibility of combining tree rings and the pdsi to reconstruct large scale drought patterns over this area

biogenic and abiogenic low mg calcite blmc and almc evaluation of seawater ree composition water masses and carbonate diagenesis the ree and shale normalized paas reesn values of modern brachiopods biogenic low mg calcite blmc represented by several species from high to low latitudes from shallow to deep waters and from warm and cold water environments define three distinct average seawater trends the warm and cold water brachiopods define two indistinguishable p 0 050 groups that mimic open ocean seawater ree chemistry exhibiting the typical lree enrichment with a slightly positive to negative ce anomaly followed by an otherwise invariant series other recent brachiopods from an essentially siliciclastic seabed environment are distinct in both ree and reesn trends from the previous two populations showing a slight enrichment in the mrees and an increasing trend in the hrees other groups of modern brachiopods are characterized by elevated reesn trends relative to the normal groups as well as by complexity of the series trends the most characteristic feature is the decrease in the hrees in these brachiopods from areas of unusual productivity i e such as upwelling currents fluvial input and aerosol dust deposition preserved brachiopods from the eocene and silurian exhibit reesn trends and ce anomalies similar to that of the open ocean modern brachiopods although their enriched ree concentrations suggest precipitation of blmc influenced by extrinsic environmental conditions preservation of the blmc was tested by comparing the ree and reesn trends of preserved eocene brachiopods to those of oligocene brachiopods that were altered in an open diagenetic system in the presence of phreatic meteoric water the altered blmc is enriched by approximately one order of magnitude in both ree and reesn trends relative to that in blmc of their preserved counterparts similarly the ree and reesn of preserved silurian brachiopod blmc were compared to those of their enclosing altered lime mudstone which exhibits features of partly closed system phreatic meteoric water diagenesis despite these differences in the diagenetic alteration systems and processes the rees and reesn trends of the blmc of altered brachiopods and of originally mixed mineralogy lime mudstones now diagenetic low mg calcite are enriched by about one order of magnitude relative to those observed in the coeval and preserved blmc in contrast to the changes in ree and reesn of carbonates exposed to phreatic meteoric water diagenesis are the ree compositions of late burial calcite cements precipitated in diagenetically open systems from burial fluids the ree and reesn trends of the burial cements mimic those of their host lime mudstone with all showing slight lree enrichment and slight hree depletion exhibiting a chevron pattern of the reesn trends the overall enrichment or depletion of the cement reesn trends relative to that of their respective host rock material reflects not only the openness of the diagenetic system but also strong differences in the elemental and ree compositions of the burial fluids evaluation of the ce ce sn and la pr pr sn anomalies suggests precipitation of the burial calcite cements essentially in equilibrium with their source fluids

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

marine to nonmarine facies transition in permian evaporites of the palo duro basin texas geochemical response the late paleozoic palo duro basin evolved from a marine to nonmarine environment as it was infilled the evaporitic part of the sequence leonardian through ochoan is composed of regressive carbonate anhydrite halite cycles that displaced open marine environments toward the south during basin filling systematic vertical changes in evaporite geochemistry through the evaporite section include increasing 87sr 86sr ratios and decreasing altered from marine 34s in anhydrite decreasing recycled bromide content of the halite and increasing meteoric influence on the stable isotopic composition of fluid inclusions in halite geochemical changes correspond to changes in evaporite sedimentology and document the evolution from marine dominated to partly nonmarine evaporites geochemical tracers when used with sedimentological and facies analysis provide reliable indicators of the sources of water and solutes in an anhydrite halite facies tract perennial intermittently stratified and ephemeral brine pool conditions affect the amount of synsedimentary recycling variable rates of reflux and marine recharge control residence times of brines in the depositional environment these are two key processes in relating evaporite geochemistry to depositional environment

fluid inclusions in sedimentary and diagenetic systems abstract some of the major problems in sedimentary geology can be solved by using fluid inclusions in sedimentary and diagenetic minerals important fluids in the sedimentary realm include atmospheric gases fresh water of meteoric origin lake water seawater mixed water evaporated water formation waters deep in basins oil and natural gas preserving a record of the distribution and composition of these fluids from the past should contribute significantly to studies of paleoclimate and global change research is essential for improving understanding of diagenetic systems and provides useful information in petroleum geology applications of fluid inclusions to sedimentary systems are not without their complexities some fluid inclusions exposed to natural conditions of increasing temperature may be altered by thermal reequilibration which results in stretching or leakage and refilling of some fluid inclusions similarly overheating in the laboratory can also cause reequilibration of fluid inclusions so fluid inclusions from the sedimentary realm must be handled carefully and protected from overheating natural overheating of fluid inclusions must be evaluated through analysis of the most finely discriminated events of fluid inclusion entrapment fluid inclusion assemblages fia consistency in homogenization temperatures within a fluid inclusion assemblage consisting of variably sized and shaped inclusions is the hallmark of a data set that has not been altered through thermal reequilibration in contrast fluid inclusion assemblages yielding variable data may have been altered through thermal reequilibration if a fluid inclusion assemblage has not been altered by thermal reequilibration its fluid inclusions may be useful as geothermometers for low and high temperature systems or useful as geobarometers applicable throughout the sedimentary realm if a fluid inclusion assemblage has been altered partially by thermal reequilibration techniques for distinguishing between altered and unaltered fluid inclusions may be applied in studies of global change fluid inclusions can be used as sensitive indicators of paleotemperature of surface environments fluid inclusions also preserve microsamples of ancient seawater and atmosphere the analysis of which could figure prominently into discussions of past changes in chemistry of the atmosphere and oceans in petroleum geology fluid inclusions have proven to be useful indicators of migration pathways of hydrocarbons they can delineate the evolution of the chemistry of hydrocarbons and they remain important in understanding the thermal history of basins and relating fluid migration events to evolution of reservoir systems in studies of diagenesis fluid inclusions can be the most definitive record most diagenetic systems are closely linked to temperature and salinity of the fluid thus fluid inclusions are sensitive indicators of diagenetic environments

tree ring width based precipitation reconstruction in zhaogaoguan china since 1805 ad abstract in order to further understand the past climate variation especially the history of drought and flood events in the east asian summer monsoon easm marginal area precipitation from previous august to current july for the period of 1805 2014 ad was reconstructed from a ring width chronology of pinus tabulaeformis in zhaogaoguan zgg a site located in the easm marginal area in northern china the transfer function can explain 46 4 adjusted to 45 4 for the loss of degrees of freedom of the variance of the observed precipitation during the calibration period 1958 2014 ad the reconstructed precipitation series revealed that the inter annual variability was very prominent 1843 and 1844 ad were the two wettest years while 1931 and 1999 ad were the two driest years we noticed that the droughts in 1900 1906 1931 1955 and 1999 ad in the reconstruction series corresponded to the severe floods in the yangtze river watershed in southern china during those same years this phenomenon confirmed the typical climate pattern of northern droughts and southern floods in china moreover the reconstructed precipitation series in zgg showed synchronous variation patterns with the other tree ring based hydrological reconstructions in the marginal area of easm on both inter annual and inter decadal scales indicating the common precipitation variation characteristics of the easm marginal area

complex magmatic and impact history prior to 4 1 ga recorded in zircon from apollo 17 south massif aphanitic breccia 73235 abstract sample 73235 is one of several aphanitic impact melt breccias collected by the apollo 17 mission at stations 2 and 3 on the slopes of the south massif this study presents a detailed investigation of internal structures and u pb ages of large zircon grains from this breccia sample new data combined with the results of previous studies of zircon grains from the same location indicate that most zircon clasts in breccias from stations 2 and 3 formed during multiple magmatic events between 4 37 and 4 31 ga although the oldest zircon crystallized at about 4 42 ga and the youngest at 4 21 ga in addition zircons from the aphanitic breccias record several impact events prior to the 3 9 ga late heavy bombardment the results indicate that the zircons probably crystallized at different locations within the procellarum kreeep terrane and were later excavated and modified by several impacts and delivered to the same locality within separate ejecta blankets this locality became a source of material that formed the aphanitic impact melt breccias of the south massif during a 3 9 ga impact however the zircons showing old impact features are not modified by this 3 9 ga impact event suggesting that i this common source area was located at the periphery of excavation cavity and ii the 3 9 ga ages recorded by the zircon grains could date large basin forming events as significant as major later 3 9 ga collisions such as imbrium and serenitatis

uranium lead ages for lunar zircons evidence for a prolonged period of granophyre formation from 4 32 to 3 88 ga the ages of a number of small fragments of lunar granophyre have been determined by the in situ u th pb isotopic analysis of zircon using a sensitive high mass resolution ion microprobe shrimp i the zircon from lunar granophyre is characterized by consistently high u and th contents most 200 500 ppm and 100 300 ppm respectively compared to zircon from mafic lunar rocks some fragments of lunar granophyre are found to be as old as 4 32 ga supporting other evidence that the original lunar magma ocean crystallized completely within 200 ma of the formation of the moon itself other fragments are as young as 3 88 ga which is much later than the time of formation of most of the lunar crust the older lunar granophyres have rare earth element ree patterns that are similar to lunar kreep whilst the younger granophyres have bow shaped ree patterns that feature a greater relative enrichment in the heavy ree the wide range of ages of numerous lunar zircons lunar granophyres and other rocks indicates that zircon forming magmatism in the lunar highlands was most active prior to 4 3 ga but continuous until at least 3 88 ga the u pb isotopic composition of much lunar zircon is near concordant but the effects of isotopic disturbance as late as 1 0 ga are observed in some zircon both within granophyre fragments recrystallized by reheating and within fragments in which the original delicate silica k feldspar granophyric intergrowth is well preserved it is therefore essential to make multiple analyses of individual zircon grains and preferably analyses of suites of zircons from lunar igneous rocks if they are to be dated reliably by the u pb method it is possible that some of the younger lunar granophyres are the product of large scale silicate liquid immiscibility within late stage differentiates but this remains unproven until remnants of demonstrably cogenetic fe rich immiscible liquid are positively identified

the evaporation path of seawater and the coprecipitation of br and k with halite brines and salt were sampled at the morton bahamas solar salt production facility on great inagua island in the bahamas the brines were analyzed by ion chromatography to define more precisely than heretofore the evaporation path of seawater to the end of the halite facies at inagua calcium carbonate begins to precipitate at a brine concentration factor of 1 8 times that of seawater gypsum begins to precipitate at a brine concentration of 3 8 times seawater and halite at a concentration factor of 10 6 three of the most concentrated brines from inagua 40 times seawater were evaporated further in the laboratory magnesium sulfate first precipitated at brine concentrations about 70 times those of seawater and potassium bearing phases began to precipitate for these brines at concentrations greater than 90 times those of seawater the distribution of coefficients of br and k between brines and halite were determined by combining analytical data for the inagua brines with measurements of the br and k content of halites from inagua and of halite which had precipitated from inagua brines during storage the observed average value of dbr is 0 032 in good agreement with some of the previous measurements the measured values of dk are highly variable 0 001 to 0 021 dk for halite precipitated early in the halite facies is in the vicinity of 0 015

the comparative behavior of apatite zircon u pb systems in apollo 14 breccias implications for the thermal history of the fra mauro formation we report secondary ion mass spectrometry sims u pb analyses of zircon and apatite from four breccia samples from the apollo 14 landing site the zircon and apatite grains occur as cogenetic minerals in lithic clasts in two of the breccias and as unrelated mineral clasts in the matrices of the other two sims u pb analyses show that the ages of zircon grains range from 4023 24 ma to 4342 5 ma whereas all apatite grains define an isochron corresponding to an age of 3926 3 ma the disparity in the ages of cogenetic apatite and zircon demonstrates that the apatite u pb systems have been completely reset at 3926 3 ma whereas the u pb system of zircon has not been noticeably disturbed at this time the apatite u pb age is slightly older than the ages determined by other methods on apollo 14 materials highlighting need to reconcile decay constants used for the u pb ar ar and rb sr systems we interpret the apatite age as a time of formation of the fra mauro formation if the interpretation of this formation as an imbrium ejecta is correct apatite also determines the timing of imbrium impact the contrast in the pb loss behavior of apatite and zircon places constraints on the temperature history of the apollo 14 breccias and we estimate from the experimentally determined pb diffusion constants and an approximation of the original depth of the excavated samples in the fra mauro formation that the breccias experienced an initial temperature of about 1300 1100 c but cooled within the first five to ten years

chemical composition of seawater in neoproterozoic results of fluid inclusion study of halite from salt range pakistan and amadeus basin australia abstract data on chemical composition of brines in primary inclusions of marine halites and on mineralogy of marine evaporites and carbonates lead to the conclusion that during the phanerozoic two long term cycles of chemical composition of seawater existed during each of those cycles seawater dominantly a na k mg ca cl ca rich type changed to a na k mg cl so 4 so 4 rich type recrystallised halite from the uppermost neoproterozoic salt range formation ca 545 ma in pakistan contains solitary inclusions indicating so 4 rich brines this supports the concept derived from the study on primary fluid inclusions from the neoproterozoic ara formation of oman so 4 rich seawater existed during latest neoproterozoic time ca 545 ma in contrast samples of recrystallised halite from the bitter springs formation 840 830 ma in australia contain inclusion brines that are entirely ca rich indicating that basin brines and seawater were ca rich during deposition of central australian evaporites these combined data supported by the timing of aragonite and calcite seas suggest that during the proterozoic significant oscillations of the chemical composition of marine brines and seawater occurred which are similar to those known to exist during the phanerozoic it is suggested that ca rich seawater dominated for a substantial period of time more than 200 ma at 650 ma this was replaced by so 4 rich seawater finally returning to ca rich seawater at 530 ma

paleotemperatures preserved in fluid inclusions in halite a variety of paleoclimate proxy records allow determination of relative warming or cooling however if we are to understand climate change quantification of past temperature fluctuations is essential our research indicates that fluid inclusions in halite can yield homogenization temperatures that record surface brine temperatures at the time of halite precipitation to avoid problems with stretching leaking and initial trapping of air samples with primary single phase liquid fluid inclusions are chilled in a freezer to nucleate vapor bubbles we tested the reliability of this method of obtaining fluid inclusion homogenization temperatures using modern salts precipitated at badwater basin death valley california homogenization temperatures correlate well with measured brine temperatures the same method is applied to fluid inclusions in pleistocene halite from a core taken at the same location in death valley results are at several scales recording diurnal temperature variations seasonal temperature fluctuations and longer term warming and cooling events that correlate with major changes in the sedimentary environment related to climate this technique is uniquely instrumental for paleoclimate studies because it offers actual not just proxy paleotemperature data 27 refs 17 figs

the analysis of fluid inclusions in halite abstract a technique has been developed to drill into fluid inclusions in halite to extract the inclusion fluids and to determine the concentration of all of the major and some of the minor constituents in these fluids the minimum diameter of usable fluid inclusions is ca 250 m after dilution the fluids are analyzed by ion chromatography and coulometry uncertainties in the concentration of the major cations and anions is on the order of 4 the analytical scheme provides much more precise analyses of inclusion fluids than have been available to date the analyses are a useful starting point for reconstructing the composition of the seawater from which the evaporite brines evolved

halite cementation and carbonate diagenesis of intra salt reservoirs from the late neoproterozoic to early cambrian ara group south oman salt basin late neoproterozoic to early cambrian carbonates of the ara group form important intra salt stringer reservoirs in the south oman salt basin differential loading of thick continental clastics above the six carbonate to evaporite cycles of the ara group led to the formation of salt diapirs encasing a predominantly self charging hydrocarbon system within partly highly overpressured carbonate bodies stringers these carbonates underwent a complex diagenetic evolution with one stage of halite cementation in a shallow early and another in a deep late burial environment early and late halite cements are defined by their microstructural relationship with solid bitumen the early phase of halite cementation is post dated by solid reservoir bitumen this phase is most pervasive towards the top of carbonate stringers where it plugs nearly all available porosity in facies with initially favourable poroperm characteristics bromine geochemistry revealed significantly higher bromine contents up to 280 p p m in the early halite compared with the late halite 173 p p m the distribution patterns and the high bromine contents of early halite are consistent with precipitation caused by seepage reflux of highly saturated brines during deposition of the overlying rock salt interval later in burial history relatively small quantities of early halite were dissolved locally and re precipitated as indicated by inclusions of streaky solid bitumen within the late halite cements late halite cement also seals fractures which show evidence for repeated reopening initially these fractures formed during a period of hydrothermal activity and were later reopened by a crack seal mechanism caused by high fluid overpressures porosity plugging by early halite cements affects the poroperm characteristics of the ara carbonates much more than the volumetrically less important late halite cement the formation mechanisms and distribution patterns of halite cementation processes in the south oman salt basin can be generalized to other petroliferous evaporite basins

shallow water evaporitic environments and their source rock potential in the major evaporitic environments on the world s surface today most organic matter accumulates in shallow subaqueous to seasonally subaerially exposed algal mat sediments given the present depositional setting and the most likely flushing by oxidizing water it is unlikely this organic matter could be preserved to form source rocks however if we place such evaporite deposition into a geologic context then there are times in the past when source rocks could have formed in shallow water settings such settings were characterized by hydrological conditions which allowed the retention of hypersaline anoxic pore waters to depths where the organic material was buried deeply enough to generate hydrocarbons when deep basin shallow water evaporite successions were laid down in basins such as the mediterranean in the late miocene the michigan basin in the silurian and other large saline giants then conditions were right for the formation of source rocks within shallow water and salt flat evaporitic environments the evaporites in these saline giants were deposited under conditions of relatively shallow water 50 m the basin never appears to have dried out but water levels changed quickly nearly equal 10 000 years from shallow to deep continual water saturation coupled with saline pore fluids prevented the inflow of fresh oxidizing groundwater into the basin center of shallow water organic rich evaporites immature hydrocarbons derived from such rocks today drip from the 5 5 m y evaporites of sicily in active salt and sulfur mines organic rich sediments could also be preserved to generate hydrocarbons in rapidly subsiding rift basins in such basins rapid burial has prevented the entrance of fresher oxygenated waters and the associated degradation and destruction of the organic matter the early continental riff stage generates the source rocks the ephemeral streams wadis and dune fields generate the reservoirs and the subsequent evaporite stage seals the reservoir

tree ring precipitation reconstruction in the chifeng weichang region china and east asian summer monsoon variation since a d 1777 1 the total precipitation of previous august to current july was reconstructed on the basis of the pinus tabulaeformis ring widths from three sites in chifeng and weichang regions china for the past 236 years the explained variance of reconstruction is 47 4 the intervals with below average precipitation 1768 2003 comprise 1779 1806 1853 1883 1926 1972 and 1980 1989 the intervals with above average precipitation consist of 1807 1852 1884 1925 1973 1979 and 1990 1999 precipitation in the study area is dependent on the east asian summer monsoon strength the reconstructed series is significantly correlated with the average dryness wetness index series of datong and beijing as well as with previous results from baiyinaobao helan mountains and even the state of mongolia a significant negative correlation r 0 63 p 0 0001 is also found between the reconstruction and our previously reconstructed temperatures of weichang for the period 1884 2002 our result suggests that the variations of the east asian summer monsoon on a decadal scale are coincident with the other regions within the environmentally sensitive zone of northern china as well as mongolia for the past 236 years and our reconstruction is representative of regional climate patterns

on the origin of fluids included in phanerozoic marine halite basic interpretation strategies abstract in addition to the use of janecke units in the nacl kcl mgcl 2 na 2 so 4 h 2 o nacl kcl mgcl 2 cacl 2 h 2 o system to classify brine origins a fast and efficient method is described to identify inclusions of evaporated seawater in ancient marine halite the method is based on the calculation of degrees of evaporation for various elements de element of brines created by different salt forming processes the de element patterns of the fluid inclusions serve as fingerprints and are characteristic of different brine types of known origin

deposition and early alteration of evaporites summary the depositional settings for primary and early diagenetic evaporite deposits generally fall into three categories marginal mixed shallow subaqueous and subaerial shallow and deep subaqueous these three environmental groupings hold for both marine and nonmarine settings although the details of continental evaporites may be far more complex than in most marine fed water bodies the primary evaporite morphologies from many continental playa hypersaline marine and marine marginal depositional settings are reasonably well understood because of the numerous detailed studies of recent holocene and cenozoic deposits that serve as models for sedimentary interpretation the sedimentological features that develop in deeper water settings are inferred based on examination of unaltered cenozoic deposits each environmental setting develops characteristic depositional features and patterns and one facies grades into the next because there may be significant physiochemical changes in water composition during deposition as well as sudden change s in both water depth and basinal circulation description and interpretation of evaporative rocks should not be based on mineralogy alone but on the distinct sedimentary characteristics of each part of a deposit in cases where sediments still reflect their primary mineralogy and morphology most of the environments can now be recognized however geochemical studies are commonly required to determine the source s of the original water the determinative geochemical techniques that presently serve as a support to sedimentologic study include studies of fluid inclusions bromine content of chloride salts and the stable isotopes of strontium sulphur carbon and oxygen only after these and perhaps other chemical analyses are considered can the full depositional history of a region be reasonably unravelled

large scale carbon isotope fractionation in evaporites and the generation of extremely 13c enriched methane petrographic fluid inclusion geochemical and gas stable isotope data are reported here for a permian zechstein evaporite sequence this deposit is a geochemically unaltered sequence bromine concentrations show a continuous evaporation profile with little postdepositional alteration in halite chemistry bacterial fermentation gases identified in primary inclusions change from an n 2 h 2 s composition in the lower middle halite series to a ch 4 h 2 composition in the upper halite and potash series carbon isotope results for ch 4 show a 1 3 c enrichment up sequence from typical biogenic values of 45 to 50 to extremely unusual 1 3 c enriched values as high as 21 the d values for these 1 3 c enriched ch 4 gases range from 240 to 377 a model is proposed for the formation of the ch 4 gases whereby the dominant isotopic fractionation process controlling the system was evaporation of the brines this generated a progressive 1 3 c enrichment in the carbon in the residual brines due to preferential loss of 1 2 co 2 to the atmosphere the resulting ch 4 generated in the sediments as evaporation and precipitation advanced recorded this 1 3 c enrichment in the carbon reservoir therefore the isotopic profile observed in this sequence today represents a primary feature with little evidence for postdepositional migration