p t d histories from quartz a case study of the application of the titaniq thermobarometer to progressive fabric development in metapelites 1 this study investigates the ability of quartz to record segments of the pressure temperature deformation p t d path in poly deformed metamorphic terranes and the associated application of the ti in quartz thermobarometer titaniq metapelites from the strafford dome eastern vermont were selected for this study because they record progressive fabric development during prograde metamorphism and have well constrained p t d histories from previous work results of this investigation are in agreement with previous studies and demonstrate that quartz in these samples records additional distinct intervals of the p t d path six preserved quartz equilibration events include 1 early prograde growth during burial 2 kyanite in quartz producing reactions 3 prenappe emplacement equilibration during isobaric heating 4 precipitation of quartz in quartz feldspar domains during crenulation cleavage development due to solution transfer 5 quartz producing chlorite out reactions during heating postnappe emplacement and 6 retrograde quartz overgrowths from an influx of siliceous fluids modeling quartz volume allows for the identification of quartz producing reactions in p t space the same may be done for ti phases to better constrain activities during reequilibration events an integration of cathodoluminescence imaging microstructural and petrographic investigation isochemical forward stability modeling and thermobarometry allows identification and interpretation of zoning patterns in quartz to unravel histories that would otherwise not be obtainable

is quartz cathodoluminescence color a reliable provenance tool a quantitative examination abstract we examined cathodoluminescence cl colors of quartz by using red 590 780 nm green 515 590 nm and blue 380 515 nm optical filters interfaced with a cathodoluminescence cl detector attached to a scanning electron microscope sem sem cl images taken through these filters were captured digitally and transferred to a computer luminescence intensities luminosities of the images were measured by using available commercial software measured luminosities of these cl images are directly related to relative intensities of red green and blue cl emissions luminosity data were then used to construct plots that display relative luminosities of the cl images acquired through the red green and blue filters an unfiltered cl image of each quartz grain generated by photons with wavelengths ranging from 200 700 nm was also acquired by subtracting the numerical luminosity values of the images acquired through the red green and blue filters from the luminosity value of the unfiltered image the contribution to total luminosity provided by cl emission in the near ultraviolet uv was calculated the cl colors of quartz from a variety of volcanic plutonic and metamorphic rocks and hydrothermal deposits were examined volcanic quartz phenocrysts have the most restricted cl color range with strongest emission intensity in the blue wavelength band cl colors of plutonic quartz overlap those of volcanic phenocrysts but extend over a broader range to include quartz that displays higher intensity of red emission cl emission in hydrothermal vein quartz is similar to that in plutonic quartz although some hydrothermal quartz exhibits stronger green cl emission than does plutonic quartz the cl colors of metamorphic quartz exhibit the widest variation overlapping the color fields of both volcanic and plutonic quartz and extending further into the red cl emission in the near uv makes a significant contribution 5 85 percent to the total luminosity of sem cl images particularly images of plutonic quartz because of overlap in the cl color ranges of volcanic plutonic metamorphic and hydrothermal quartz unambiguous identification of quartz provenance on the basis of cl color alone is problematic it is difficult to distinguish between volcanic and some plutonic quartz and between some plutonic and hydrothermal quartz or to distinguish magmatic quartz from metamorphic quartz that exhibits blue cl color only metamorphic quartz that exhibits moderately strong red emission appears distinguishable on the basis of color from quartz of other origins our work thus suggests that cl color is not a reliable indicator of quartz provenance

cathodoluminescence of quartz from sandstones interpretation of the uv range by determination of trace element distributions and fluid inclusion p t x properties in authigenic quartz quartz overgrowths from keuper sandstones of the paris basin were examined using cathodoluminescence cl microscopy and spectroscopy coupled with a scanning electron microscope sem with the use of standard cold cl equipment it was observed that the emission of authigenic quartz is much less intense than that of detrital quartz grains but a reversal of intensity was observed with scanned cl in the 200 800 nm range the main cl emission band of diagenetic quartz is at 330 340 nm in the uv range with other bands in the visible range the determination of trace element distributions in authigenic quartz by in situ analyses and by sims imagery reveals the correlation of the 330 340 nm emission band with the highest al and li contents the cathodoluminescence emission of diagenetic quartz in the uv range appears to be influenced by the coupled substitution of al and li into the crystal two explanations are suggested 1 ai li or both serve as activators and 2 the incorporation of al and li causes lattice defects that lead to an enhancement of the intrinsic luminescence trace element analyses and fluid inclusion studies revealed that quartz overgrowths precipitated from a fluid that partially originated from an li enriched primary brine derived from eastern triassic evaporites of the paris basin the specific cl emission band in the uv range can be linked to the diagenetic environment the chemistry of the fluids appears to be the essential parameter whereas precipitation temperatures do not influence the occurrence of such emissions

geochemistry of formation waters from the wolfcamp and cline shales insights into brine origin reservoir connectivity and fluid flow in the permian basin usa abstract despite being one of the most important oil producing provinces in the united states information on basinal hydrogeology and fluid flow in the permian basin of texas and new mexico is lacking the source and geochemistry of brines from the basin were investigated ordovician to guadalupian age reservoirs by combining previously published data from conventional reservoirs with geochemical results for 39 new produced water samples with a focus on those from shales salinity of the ca cl type brines in the basin generally increases with depth reaching a maximum in devonian median 154 g l reservoirs followed by decreases in salinity in the silurian median 77 g l and ordovician median 70 g l reservoirs isotopic data for b o h and sr and ion chemistry indicate three major types of water lower salinity fluids 100 g l isotopically heavy o and h water in leonardian permian to pennsylvanian reservoirs 2 3 2 km depth is evaporated late permian seawater water from the permian wolfcamp and pennsylvanian cline shales which are isotopically similar but lower in salinity and enriched in alkalis appear to have developed their composition due to post illitization diffusion into the shales samples from the cline shale are further enriched with nh 4 br i and isotopically light b sourced from the breakdown of marine kerogen in the unit lower salinity waters 3 km depth which plot near the modern local meteoric water line are distinct from the water in overlying reservoirs we propose that these deep meteoric waters are part of a newly identified hydrogeologic unit the deep basin meteoric aquifer system chemical isotopic and pressure data suggest that despite over pressuring in the wolfcamp shale there is little potential for vertical fluid migration to the surface environment via natural conduits

cathodoluminescence characteristics of archean volcanogenic massive sulfide related quartz noranda ben nevis and matagami districts abitibi subprovince canada 1 the cathodoluminescence cl of quartz from ore stockwork veins and interstitial fillings between lava pillows from the 2 7 ga noranda ben nevis and matagami volcanogenic massive sulfide vms districts abitibi greenstone belt has been investigated using the hot cathode technique hc1 lm system to assess the potential of these various sample types to host primary seafloor vms related fluids trapped as inclusions in minerals with primary depositional morphologies the cl responses indicate that the various quartz types are of hydrothermal origin and are therefore a potential host for primary hydrothermal fluid inclusions most notable is a transient t 120 s blue cl characteristic of hydrothermal quartz observed in most samples cl characteristics are similar over 250 km indicating coherent nonrandom behavior furthermore in ore and stockwork material from the matagami and noranda districts respectively cl reveals primary concentric growth zoned quartz that predates pulses of sulfide deposition clear evidence that the quartz is undeformed and directly related to vms mineralization these growth zones are not apparent in transmitted light in addition ore and stockwork quartz commonly show a very unstable t 30 s yellow cl coincident with microfractures and grain boundaries defining areas affected by secondary hydrothermal activity in ore from matagami local zones of nontransient brown cl may reflect strain zones associated with the deformation and recrystallization of the massive sulfide mound and indicate that such modifications can be recognized and are minor in the investigated cases cl clearly reveals pseudo hexagonal apparently zoned structures in sulfide mineralized breccia pipe quartz from the ben nevis area these structures and their host quartz characterized by a very unstable t 20 s bright yellow cl are interpreted as recrystallized quartz that has undergone rapid growth from a strongly supersaturated solution and noncrystalline precursor the cl also clearly reveals colloform crustiform textures indicative of open space filling these textures are not visible optically

intensity of quartz cathodoluminescence and trace element content in quartz from the porphyry copper deposit at butte montana textures of hydrothermal quartz revealed by cathodoluminescence using a scanning electron microscope sem cl refl ect the physical and chemical environment of quartz formation variations in intensity of sem cl can be used to distinguish among quartz from superimposed mineralization events in a single vein in this study we present a technique to quantify the cathodoluminescent intensity of quartz within individual and among multiple samples to relate luminescence intensity to specific mineralizing events this technique has been applied to plutonic quartz and three generations of hydrothermal veins at the porphyry copper deposit in butte montana analyzed veins include early quartz molybdenite veins with potassic alteration pyrite quartz veins with sericitic alteration and main stage veins with intense sericitic alteration cl intensity of quartz is diagnostic of each mineralizing event and can be used to fingerprint quartz and its fluid inclusions isotopes trace elements etc from specific mineralizing episodes furthermore cl intensity increases proportional to temperature of quartz formation such that plutonic quartz from the butte quartz monzonite bqm that crystallized at temperatures near 750 c luminesces with the highest intensity whereas quartz that precipitated at 250 c in main stage veins luminesces with the least intensity trace element analyses via electron microprobe and laser ablation icp ms indicate that plutonic quartz and each generation of hydrothermal quartz from butte is dominated by characteristic trace amounts of al p ti and fe thus in addition to cl intensity each generation of quartz can be distinguished based on its unique trace element content aluminum is generally the most abundant element in all generations of quartz typically between 50 and 200 ppm but low temperature main stage quartz containing 400 to 3600 ppm al is enriched by an order of magnitude relative to all other quartz generations phosphorous is present in abundances between 25 and 75 ppm and p concentrations in quartz show little variation among quartz generations iron is the least abundant of these elements in most quartz types and is slightly enriched in cl dark quartz in pyrite quartz veins with sericitic alteration titanium is directly correlated with both temperature of quartz precipitation and intensity of quartz luminescence such that bqm quartz contains hundreds of ppm ti whereas main stage quartz contains less than 10 ppm ti our results suggest that ti concentration in quartz is controlled by temperature of quartz precipitation and that increased ti concentrations in quartz may be responsible for increased cl intensities

reequilibration of fluid inclusions in low temperature calcium carbonate cement calcium carbonate cements precipitated in low temperature near surface vadose environments contain fluid inclusions of variable vapor to liquid ratios that yield variable homogenization temperatures cements precipitated in low temperature phreatic environments contain one phase all liquid fluid inclusions neomorphism of unstable calcium carbonate phases may cause reequilibration of fluid inclusions stable calcium carbonate cements of low temperature origin which have been deeply buried contain fluid inclusions of variable homogenization temperature and variable salt composition most inclusion fluids are not representative of the fluids present during cement growth and are more indicative of burial pore fluids therefore low temperature fluid inclusions probably reequilibrate with burial fluids during progressive burial reequilibration is likely caused by high internal pressures in inclusions which result in hydrofracturing the resulting fluid inclusions population could contain a nearly complete record of burial fluids in which a particular rock has been bathed

high integrated fluid rock ratios during metamorphism at naxos evidence from carbon isotopes of calcite in schists and fluid inclusions calcite in schists of the metamorphic complex at naxos is depleted both in 13c and in 18o with respect to massive marbles this effect is attributed to isotope exchange with circulating co2 rich fluids which had an x text co text 2 0 5 according to fluid inclusions the carbon isotopic composition of the calcites is close to equilibrium with fluid inclusion co2 at metamorphic temperatures mass balance calculations assuming initial 13c values of 0 for calcite and 5 for the fluid give integrated fluid rock volume ratios between 0 1 and 2 0 such high fluid rock ratios are supported by observations on the distribution of co2 h2o ratios of fluid inclusions carbon isotopic compositions of fluid inclusion co2 and oxygen isotope systematics of silicates

present day heat flow thermal history and tectonic subsidence of the east china sea basin the east china sea basin is located in the convergence area between the eurasian plate the pacific plate and the philippine sea plate and consists of two depressions the taibei depression in the west and the xihu depression in the east heat flow measurements show that the east china sea basin is characterized by present day heat flow around 70 6 mw m 2 varying between 55 and 88 mw m 2 no significant difference in heat flow is observed between the xihu and the taibei depressions thermal history reconstruction using vitrinite reflectance suggests that the thermal history was however different in the taibei and the xihu depressions paleo heat flow values when the pretertiary formations experienced their maximum temperature at the end of the paleocene reached a mean of 82 mw m 2 in the taibei depression much higher than the present day value the lower tertiary sediments in the xihu depression experienced maximum temperatures at the end of oligocene 35 4 23 3 ma and reached a mean paleo heat flow value of 83 mw m 2 tectonic subsidence analysis shows that the timing of the major rifting episode was different across the east china sea basin the rifting occurred from the late cretaceous w65 ma to the early eocene w55 ma in the taibei depression followed by thermal subsidence from the late eocene to the end of miocene 23 3 5 2 ma in contrast in the xihu depression the initial subsidence lasted until the early miocene and thermal subsidence to the end of miocene from pliocene to the present an accelerated subsidence took place all along the west pacific margin of asia significant thicknesses of strata were removed from the unconformities in the basin the mean amount of erosion was 1147 m from the paleocene and 1208 m above the oligocene in the taibei depression and 1409 m from the oligocene in the xihu depression q 2004 elsevier ltd all rights reserved

ion microprobe analysis of oxygen isotope ratios in quartz from skye granite healed micro cracks fluid flow and hydrothermal exchange quartz grains in hydrothermally altered granites from the isle of skye are highly heterogeneous and not equilibrated in oxygen isotope ratio at the 20 m scale ion microprobe analysis of one grain shows a gradient of 13 over 400 m and a greater range in 18o than all quartz previously analyzed on the isle of skye other crystals from the same outcrop are homogeneous digitized cathodoluminescence images reveal patterns of magmatic zoning and brittle fracturing not otherwise detectable the ion probe analysis correlates low 18o values on a micro scale to one set of healed cracks thus quartz exchanges oxygen isotopes primarily by solution and reprecipitation along fractures in contrast to more reactive feldspar that appears to exchange from the grain boundary inward macroscopic models of isotope exchange are not realistic for these rocks the flow of hydrothermal fluids was heterogeneous anisotropic and crack controlled

application of cathodoluminescence to magmatic quartz in a tin granite case study from the schellerhau granite complex eastern erzgebirge germany a model of the cooling history of tin bearing granitic magma forming the schellerhau granites eastern erzgebirge germany is shown on the basis of quartz textures similar grain size similar grain habit and correlatable growth textures of phenocrysts in different granite varieties give proof of a common crystallization history before the melts of the schellerhau granite varieties were intruded four nucleation events occurred during crystallization in different crustal levels between about 20 and 1 km depth the parental melt of the schellerhau granites is interpreted to have contained 2 5 wt h2o originally the water content of the melt during the subvolcanic intrusion stage amounted to more than 5 wt and characterizes highly evolved residual melts that enable the formation of tin deposits this study contributes to a better understanding of the development and behaviour of fractionated tin bearing granitic melts and links quartz cathodoluminescence cl with microanalytical studies

fluid regimes during late stages of a continental collision physical chemical and stable isotope measurements of fluid inclusions in fissure quartz from a geotraverse through the central alps switzerland fluid evolution during neo alpine metamorphism during late stages of the continental collision between europe and africa was studied by analyzing fluid inclusions in alpine fissure quartz collected in forty nine localities along a geotraverse through the central alps switzerland the methods employed include microthermometry micro raman spectroscopy k na thermometry and stable isotope analysis early fluid inclusions provide evidence of close to peak metamorphic temperatures of the late tertiary or neo alpine metamorphic event fluid composition evolved along the geotraverse from north to south as follows higher hydrocarbons were dominant in the low and medium grade diagenetic zones methane was the main volatile in the high grade diagenetic and low grade anchizone water dominated in the highgrade anchizone and low grade epizone with co2 10 mol in the high grade epizone and in the mesozone higher hydrocarbons and ch4 were the products of kerogen maturation and cracking of preexisting petroleum large water supplies originated from the dehydration of cooler metasedimentary rocks that were overthrust by crystalline basements of the lepontines aar and gotthard massifs carbon isotope analyses suggest that the co2 component was derived from oxidation of graphitic matter especially in the vicinity of sulfate bearing metasediments and from decarbonation reactions in the aar and gotthard massifs as well as in the helvetic axen nappe and its underlying north helvetic flysch high fluid pressures prevailed and favored nappe transport by contrast in the southern lepontine area very low early fluid pressures were probably related to dry rocks and scarce metasediments and to high geothermal gradients that resulted from intense uplift and erosion between 26 and 18 ma retrograde fluid evolution was recorded by a succession of fluid inclusion populations in each alpine fissure it was controlled by uplift and cooling and characterized by decreasing contents of volatiles and an increase in 18o of host quartz tectonic activity led to episodic pressure drops of at least 0 5 to 2 kbar and promoted fluid unmixing channelized flow and rapid growth of skeletal quartz channelized rather than pervasive fluid migration at temperatures 450 c and under conditions of brittle deformation is documented by episodic increases in salinity and by fluid flushing through the massifs there is stable isotope evidence for involvement of meteoric water only in late crystallizing quartz formation of alpine fissures and fissure minerals was the result of a unique coincidence of late continental collision 450 c fluid expulsion from overthrust metasediments uplift and erosion

carbon dioxide in clastic rocks and silicate hydrolysis the amount of carbon dioxide in clastic rocks in sedimentary basins increases with depth organic matter dissolved organic species and dissolution of carbonate minerals have been suggested as sources of co sub 2 which increases in abundance with depth and temperature isotopic compositions of aqueous hco sub 3 sup minus gaseous co sub 2 and calcite from conventional hydrocarbon wells and steam assisted recovery of heavy oil suggest that calcite or other carbonate minerals are the source of co sub 2 particularly at higher temperatures detailed examination of the stability of diagenetic minerals such as kaolinite smectite and analcime among others relative to the coexisting waters indicates that silicate hydrolysis is the driving force for dissolution of carbonate minerals and the ultimate source of abundant co sub 2 in clastic rocks in diagenetic environments at temperatures over approximately 100 c

basin scale thermal and fluid flow histories revealed by carbonate clumped isotopes δ47 middle jurassic carbonates of the paris basin depocentre the reconstruction of past diagenetic conditions in sedimentary basins is often under constrained this results from both the analytical challenge of performing the required analyses on the minute sample amounts available from diagenetic mineral phases and the lack of tracers for some of the diagenetic parameters the carbonate clumped isotopes thermometry 47 opens new perspectives for unravelling the temperatures of diagenetic phases together with the source of their parent fluids two parameters that are otherwise impossible to constrain in the absence of exploitable fluid inclusions here is reported the study of a large number of sedimentary and diagenetic carbonate phases from middle jurassic reservoirs of the paris basin depocentre by combining detailed petrographic observations with a large number of 47 data n 45 on a well documented paragenetic sequence including calcite and dolomite burial cements the data reveal carbonate crystallization at temperatures between 29 c and 98 c from fluids with 18owater values between 7 and 2 in response to the progressive burial and uplift of the paris basin throughout 165 myr of basin evolution coupled to the time temperature evolution previously estimated from thermal maturity modelling these temperatures allow determining the timing of four successive cementation episodes the overall dataset indicates a history of complex water mixing with a significant contribution of hypersaline waters from the triassic aquifers migrated upward along faults during the cretaceous subsidence of the basin subsequent large scale infiltrations of meteoric waters induced a dilution of these pre existing brines in response to the paris basin uplift in the tertiary overall the data presented here allow proposing an integrated approach to characterize the cementation events affecting the studied carbonate reservoir units based on temperature oxygen isotope composition and salinity of the parent fluids as well as on petrographic grounds this article is protected by copyright all rights reserved

geochemistry and occurrence of inorganic gas accumulations in chinese sedimentary basins abstract inorganic gases are commonly seen in eastern china and occasionally in southern china from the shallow water columns above hot and cold springs the gases contain 68 to nearly 100 co2 with 13 c co 2 and 13c1 values in the range of 1 18 to 6 00 and 19 48 to 24 94 respectively all of the 34 large inorganic co2 and one inorganic methane accumulations discovered in china are distributed in eastern parts of the country from both onshore and continental shelf basins no commercial inorganic gas accumulation has been found in central and western china this is a review of the occurrence and geochemical characteristics of inorganic gas accumulations in chinese sedimentary basins a detailed study of gas samples collected from four representative inorganic co2 pools and one possible inorganic methane pool indicates that inorganic alkane gases typically show 13c1 values greater than 10 versus pdb mostly 30 with a positive stable carbon isotope sequence of 13c1 13c2 13c3 13c4 inorganic gases also tend to show less negative 13 c co 2 values 10 than biogenic gases

pvtx properties of the co2 h2o and co2 h2o nacl systems below 647 k assessment of experimental data and thermodynamic models evaluation of co2 sequestration in formation brine or in seawater needs highly accurate experimental data or models of pressure volume temperature composition pvtx properties for the co2 h2o and co2 h2o nacl systems this paper presents a comprehensive review of the experimental pvtx properties and the thermodynamic models of these two systems the following conclusions are drawn from the review 1 about two thirds of experimental data are consistent with each other where the uncertainty in liquid volumes is within 0 5 and that in gas volumes within 2 however this accuracy is not sufficient for assessing co2 sequestration among the data sets for liquids only a few are available for accurate modeling of co2 sequestration these data have an error of about 0 1 on average roughly covering from 273 to 642 k and from 1 to 35 mpa 2 there is a shortage of volumetric data of saturated vapor phase 3 there are only a few data sets for the ternary liquids and they are inconsistent with each other where only a couple of data sets can be used to test a predictive density model for co2 sequestration 4 although there are a few models with accuracy close to that of experiments none of them is accurate enough for co2 sequestration modeling which normally needs an accuracy of density better than 0 1 some calculations are made available on

ch4 accumulation characteristics and relationship with deep co2 fluid in lishui sag east china sea basin abstract co accumulation of carbon dioxide and hydrocarbon gas is common and widely existing in oil and gas basins such two natural pools are located in lishui sag east china sea shelf basin as a favorable prospecting area for exploration co2 gas derived from inorganic mantle sources and co2 accumulation times have been investigated in this study petrographic observation shows pure ch4 ch4 rich h2o rich and hybrid ch4 co2 fluid inclusions exist in healed micro fractures and overgrowths of quartz mineral in palaeocene reservoirs of lishui sag the pressure temperature time composition pvt x properties of ch4 bearing inclusions were obtained by raman quantitative analysis and thermodynamic models these results provide important constraints on the p t entrapment conditions and predict relative accumulation time of ch4 fluid combination of carbon isotope analyses inclusion petrography microthermometry pt entrapment conditions of ch4 bearing inclusions hydrocarbon generation and simulation of burial history permit to assign periods of ch4 fluid activity and its sequence with co2 fluid methane charging time occurs during two stages in ls a low density ch4 fluid 0 10 g cm3 or lower were trapped during late oligocene 30 20 ma and high density 0 115 g cm3 during a pliocene 8 1 ma ch4 accumulation event co2 fluid accumulation miocene 21 4 ma displaced the methane gas trapped in the early stage pliocene ch4 fluid partial displaced miocene co2 fluid in well b only high density 0 144 0 153 g cm3 recorded a late oligocene to early miocene 36 19 ma ch4 accumulation event pliocene 5 3 ma co2 fluid displaced early ch4 fluid micro thermometry composition of fluid inclusion features of reservoir thermal maturity reflect hydrothermal fluid vertical migration and the existence of supercritical co2 extraction

porphyry cu mo stockwork formation by dynamic transient hydrothermal pulses mineralogic insights from the deposit at butte montana the systematic distribution of vein and alteration mineral assemblages in porphyry cu deposits largely arises from changes in the temperature and pressure of fluids that traversed fractures throughout the hydrothermal system magmatic and hydrothermal minerals record the complex history of the fluctuating temperature and pressure regime as hydrothermal fluids transfer heat from their magmatic source to cold wall rock in response to lithostatic to hydrostatic pressure variations we examine the thermal profile of the porphyry cu mo deposit in butte montana by determining formation temperatures for magmatic and hydrothermal samples representing different time frames and depths within the deposit in context with sample pressure estimates we use three independent mineral thermobarometers ti in quartz zr in rutile and x mg ti in biotite from which we estimate that final dike injection temperature and hence the initial magmatic hydrothermal fluid temperature was 700 c while the ambient host rock temperature was 450 to 500 c we find a magmatic hydrothermal continuum represented in hydrothermal veins ranging from 710 to

origin and accumulation of carbon dioxide in the huanghua depression bohai bay basin china the co2 content in natural gas in the huanghua depression bohai bay basin china is highly variable ranging from 0 003 to 99 6 understanding the origin and distribution of the co2 is important to assess risk prior to drilling this study uses gas geochemistry to identify the origins of co2 in the sedimentary basin and places these findings within a geologic context chemical compositions 3he 4he and 40ar 36ar were measured for 50 gas samples collected from gas and oil producing wells located in different tectonic regions in the depression from these analyses we determined that the co2 in the huanghua depression originated from three sources thermal decomposition of organic matter thermal decomposition of carbonate minerals and mantle degassing gases with low amounts 3 of co2 tend to be organogenic this organogenic co2 occurs in hydrocarbon accumulations and is characterized by values ranging from 20 to 10 and low 3he 4he r ra 1 herein r and ra represent the 3he 4he ratio of sample and air respectively carbon dioxide originating from thermal carbonate decomposition occurs as a minor component 10 in hydrocarbon gas accumulations and is characterized by a narrow range of 2 to 2 and r ra 1 huanghua depression natural gases with co2 content in excess of 15 resulted from mantle degassing and mainly occur at the intersection of faults these gases have 3he 4he ratios in excess of atmospheric value r ra 1 and ranging from 5 to 3 volatiles from mantle degassing during the postmagmatic stage are the most likely major source for co2 in these high co2 content reservoirs basement faults likely provide pathways for the upward migration of co2 rich mantle fluids consequently co2 rich gas pools are locally concentrated in the gangxi and dazhongwang fault zones within the depression

genetic significance of the trace element content in metamorphic and hydrothermal quartz a reconnaissance study abstract a reconnaissance study on trace elements in metamorphic and hydrothermal quartz was carried out using quartz samples from the tin district erzgebirge germany the gold mineralization at kasperske hory czech republic and the gold quartz vein deposits muruntau and myutenbai uzbekistan a new method of sample preparation has been developed to prepare pure quartz samples by combining conventional hand picking with microscopic and spectroscopic studies as well as acid wash etch procedures preparation of monomineralic samples was followed by sample dissolution and measurement by icp ms the metamorphic quartz has very low concentrations of li 0 4 ppm al 30 ppm k 35 ppm rb 50 ppb sr 0 3 ppm and y 15 ppb moreover it is characterized by light rare earth element enriched lanthanide distribution patterns lacking eu anomalies the low element concentrations in metamorphic quartz are interpreted to result from recrystallization metamorphic quartz from alteration halos enveloping tin and gold deposits has distinctly different trace element signatures these differences are related to the hydrothermal overprint of the pre existing metamorphic quartz by the mineralizing fluids hydrothermally altered metamorphic quartz from tin deposits has elevated concentrations of li 0 9 ppm al 50 ppm k 45 ppm rb 250 ppb and y 40 ppb whereas altered metamorphic quartz from gold deposits is characterized by elevated concentrations of sr 0 5 ppm the rare earth element distribution patterns of altered metamorphic quartz show variable enrichments of the heavy rare earth elements and frequently display positive eu anomalies hydrothermal vein quartz from the gold deposits usually has elevated al 50 ppm and sr 0 6 ppm contents the lanthanide distribution patterns exhibit variable enrichments of the heavy rare earth elements and commonly show positive eu anomalies the elevated sr concentrations in the quartz from gold deposits are best explained by sr release during feldspar alteration in the wall rocks this mechanism may also account for the relative enrichment of eu in the mineralizing fluids although other processes may not be unambiguously ruled out

permian triassic red stained albitized profiles in the granitic basement of ne spain evidence for deep alteration related to the triassic palaeosurface extensive areas of the variscan granitic basement in ne spain display profiles of red stained albitized facies characterized by albitization of ca plagioclase chloritization of biotite and microclinization of orthoclase along with the alteration of igneous quartz to secondary cl dark quartz these profiles have a geopetal structure beneath the triassic unconformity with a very intense and pervasive alteration in the upper part that progressively decreases with depth to 150 200 m where the alteration is restricted to the walls of fractures the red albitized facies contains secondary maghemite and hematite that indicate oxidizing conditions dating of microclinized orthoclase and secondary monazite that have formed in the red stained albitized facies yielded k ar and u th pbtotal ages of 240 and 250 ma respectively suggesting that the alteration developed during the permian triassic period the geopetal disposition of the red albitized profile with respect to the triassic unconformity its large regional extent and the fracture controlled alteration in the lower part of the profile indicate groundwater interaction the 18o values of albitized plagioclase 11 microclinized orthoclase 13 and secondary cl dark quartz 12 suggest that the alteration temperature was about 55 c this low temperature suggests that the alteration occurred during interaction of the granitic rocks with na rich fluids below a surficial weathering mantle on the permian triassic palaeosurface the latter is possibly related to triassic evaporitic environments in long lasting stable landscapes in which na rich solutions infiltrated deep regional groundwaters

isotope geochemistry of fluid inclusions in permian halite with implications for the isotopic history of ocean water and the origin of saline formation waters abstract d and 18o values have been determined for fluid inclusions in 45 samples of permian halite the inclusions are enriched in 18o relative to the meteoric water line but are depleted in d relative to ocean water inclusions with the more positive values coincide with the isotopic composition expected for evaporating sea water which follows a hooked trajectory on a d 18o diagram inclusions with more negative values may represent more highly evaporated sea water but probably reflect synsedimentary or diagenetic mixing of meteoric water with evaporite brines the isotope systematics in these inclusions are sufficiently similar to those of a modern evaporite pan to indicate that permian sea water was isotopically similar to modern sea water connate evaporite brines can have negative values because of the probable hooked isotope trajectory of evaporating sea water and or synsedimentary mixing of evaporite brines with meteoric waters subsurface formation waters composed of mixtures of remnant primary evaporite brines and later meteoric waters may be more common than previous isotopic evidence has suggested

hydrogeology and geochemistry of the ogallala aquifer southern high plains the ogallala aquifer which underlies the southern high plains consists of saturated sediments of the ogallala formation neogene that are deposited mainly as a set of humid type alluvial fans derived from the rocky mountains the ogallala aquifer the main source of water for the high plains of texas and new mexico has been severely depleted by extensive pumpage the hydrology and geochemistry of the aquifer are controlled by the surface topography of the underlying formations and by the thickness and permeability of the alluvial fan deposits axes of three major alluvial fans trend from northwest to southeast the fans have increased thickness and permeability compared with interfan areas flow lines follow the orientation of the alluvial fans along these major axes the saturated section is thick and the chemical composition is relatively constant ca hco3 to mixed cation hco3 water depleted in 18o d and tritium external effects on the chemical composition are less pronounced the aquifer is thinner and less permeable in areas between major fan axes and along the caprock escarpment in these areas groundwater can discharge from aquifers in the cretaceous triassic and permian formations into the ogallala formation cross formational movement of water and low permeabilities in the ogallala formation result in varying hydrochemical facies and in isotopic compositions that differ from those of the major depositional areas areas where upward cross formational flow occurs are evident by the presence of permeable contacts between the ogallala and the underlying formations water level head differences and chemical and isotopic similarities secondary factors that locally affect the chemical composition of ogallala formation groundwater include contamination from evaporating saline lakes agricultural chemicals and fertilizers and oil field brines impact of chemicals and brines may increase in the future because much of these contaminants may still be moving through the unsaturated zone toward the water table

the fate of mantle derived carbon in a continental sedimentary basin integration of c he relationships and stable isotope signatures abstract the isotopic composition and abundances of the rare gases he ne and ar and active gases co2 ch4 have been determined in a series of commercial gas reservoirs in the pannonian and vienna basins of hungary and austria respectively in these zones of continental extension significant components of mantle derived 4he up to 39 8 and 21ne up to 58 are identified the results of this study indicate a major component of mantle derived carbon in these systems as well ranging in composition from close to 100 co2 to ch4 dominated reservoirs with trace concentrations ppm of co2 these gas reservoirs provide a unique opportunity to examine the relationship of the conservative rare gases to the active gas components and to examine the sources and sinks for mantle and crustal derived carbon phases with the exception of kismarja gas field which shows evidence of addition of 3he depleted crustal co2 all gas fields exhibit a trend whereby the most co2 rich samples approach co 2 3 he mntl values similar to morb 2 109 to 7 109 while co2 depleted samples extend to co 2 3 he mntl values as low as 105 the lack of any correlation of co 2 3 he mntl ratios with r ra values indicates the observed trends are not a function of mixing between crustal and mantle derived endmembers but instead reflect progressive loss of the mantle derived co2 carrier phase during volatile transport and emplacement in the continental crust based on stable isotopic signatures from the kismarja field a crustal co2 endmember with an isotopic composition of 6 8 and a mantle co2 endmember with an isotopic composition no more depleted in 13c than 5 0 can be identified one of the few instances where the isotopic signatures of mantle and crustal derived co2 can be reliably distinguished in a continental setting covariation in 13cco2 and 13cch4 values in the gas fields is used to place constraints on two alternative models whereby the trends in percent co2 and co 2 3 he mntl ratios can be accounted for by 1 loss of the mantle derived co2 carrier phase 2 addition of crustal derived co2 3 addition of crustal derived thermogenic ch4 and potentially 4 conversion of the co2mntl carrier phase to mantle derived ch4 based on an estimated total mantle 4he flux for the pannonian basin of 4 2 108 atoms m 2 s 1 mantle carbon flux estimates for this basin alone range from 3 108 g c yr to 1 109 g c yr which over the lifetime of the basin is only 4 5 orders of magnitude less than flux estimates based on the total area of the spreading ridges clearly the addition of mantle derived carbon to the crust in areas of continental extension is significant and may have been previously underestimated we demonstrate here that integration of 13c data with rare gas isotopic tracers provides an important tool in constraining models of mantle carbon sources and sinks in continental settings

cathodoluminescence imaging and titanium thermometry in metamorphic quartz cathodoluminescence cl of quartz from metamorphic rocks representing a range of conditions from the garnet grade to the migmatite grade reveals a variety of textures that is a function of metamorphic grade and deformation history ti concentrations determined by electron microprobe and ion microprobe generally correlate with cl intensity blue wavelengths and application of the ti in quartz thermometer titaniq reflects the temperature of quartz growth or recrystallization and in some settings modification by diffusion quartz from garnet grade samples is not visibly zoned records temperatures of 425 475 c and is interpreted to have recrystallized during fabric formation quartz grains from staurolite grade samples are zoned in cl with markedly darker cores and brighter rims some of which are interpreted to have been produced by the dominant staurolite producing reaction whereas others are interpreted as having formed by diffusion of ti into quartz rims quartz from the matrix of kyanite and sillimanite grade samples are generally unzoned although locally displays slightly brighter rims higher ti quartz inclusions within garnet and staurolite have distinctly brighter rims which are interpreted as having been produced by diffusive exchange with the host mineral quartz from migmatite grade samples displays highly variable cl intensity which is dependent on the location of the grain matrix grains in melanosomes are largely unzoned or rarely zoned with darker cores leucosome quartz is strongly zoned with bright cores and dark rims and is interpreted as having formed during crystallization of the melt locally within the leucosome is observed oscillatory zoned quartz which is interpreted as a subsolidus recrystallization to achieve strain relaxation quartz inclusions within garnet or plagioclase crystals often show bright domains separated by zones of dark cl these enigmatic textures possibly reflect local melting fluxed by fluid inclusions temperatures calculated from the ti in quartz thermometer are a function of the metamorphic grade of the sample the textural setting of the quartz the reaction history and the deformation history of the rock the titaniq temperatures can be used to constrain the conditions at which various metamorphic processes have occurred

melt and fluid inclusions in hydrothermal veins the magmatic to hydrothermal evolution of the elatsite porphyry cu au deposit bulgaria the magmatic to hydrothermal transition in the late cretaceous elatsite porphyry cu au mo platinum group element deposit has been studied in a suite of samples with clear timing relations between porphyry dikes magmatic hydrothermal veins silicate melt inclusions in quartz veins fluid inclusion generations and ore minerals ore mineralization occurs late at temperatures 200 to 300 c below those of the early multistage interplay between magmatic and hydrothermal processes at near magmatic temperature pressure conditions crosscutting relations and petrography indicate that shortly after the intrusion of the earliest monzodioritic dikes fluids precipitated a first generation of granular quartz veins accompanied by potassic alteration the second vein generation with crystalline quartz textures and k feldspar alteration halos formed at the same time as the second granodioritic pulse of porphyry intrusions cathodoluminescence imaging of quartz growth textures reveals that the earliest fluid inclusions in the crystalline quartz veins are of intermediate density and 8 wt nacl equiv salinity probably trapped at near lithostatic pressures of 1 200 to 1 300 bars at near magmatic temperatures 730 c and implies a depth of 4 to 5 km depressurization led to phase separation indicated by a first generation of coexisting brine and vapor inclusions trapped at temperatures of 640 c and suprahydrostatic pressures of 920 bars a second quartz generation in crystalline quartz veins precipitated during progressive depressurization and hosts assemblages of coexisting brine vapor and silicate melt inclusions trapped at temperatures in excess of 600 c and suprahydrostatic pressures of 630 to 880 bars some open spaced quartz veins were filled with aplite during this stage field relations and geochemical evidence suggest that the aplites as well as the silicate melt inclusions in hydrothermal quartz veins represent volumetrically minor residual melts that evolved directly from granodiorite porphyries at the level of deposit formation and do not represent aliquots of metal supplying magma at depth fluid inclusions coexisting with the silicate melt inclusions are metal rich but these fluids predate sulfide precipitation and are therefore not the dominant fluids responsible for the cu au mineralization at elatsite melt fluid metal separation processes recorded in these co trapped silicate melt and fluid inclusions in vein quartz are small scale local phenomena and do not appear to be suited for understanding and quantifying metal segregation in the deeper source microthermometry data of fluid inclusions trapped during the later stages of the formation of the second quartz generation show further depressurization to 260 to 325 bars and cooling to 460 c representing a hot hydrostatic regime bornite chalcopyrite and magnetite seem to be slightly later precipitated at temperatures 460 c in separate veins or opened spaces of preexisting veins dissolution textures of the second quartz generation indicate a subsequent local redissolution of vein quartz most likely as a result of passing through a window of retrograde quartz solubility upon further cooling below 460 c the next economically most important chalcopyrite pyrite stage is largely devoid of quartz precipitation and is mostly expressed as paint veins due to the lack of fluid inclusions the temperature pressure conditions of formation of these veins could not be constrained the waning phase of hydrothermal activity is represented by a quartz carbonate zeolite stage formed at low temperature 145 c as indicated by microthermometry of fluid inclusions trapped in quartz from this stage laser ablation inductively coupled plasma mass spectrometry analyses of fluid inclusions show very high cu contents in early intermediate density fluid inclusions and in the first vapor inclusion generation followed by a drastic decrease in the second generation of vapor inclusions the decrease correlates with the appearance of anhydrite inclusions in the second quartz generation and may indicate that a lack of sulfur in these later vapor inclusions led to cu partitioning into the brine alternatively it is also possible that unlike early vapor inclusions the later vapor inclusions were not susceptible to postentrapment copper enrichment in accordance with recent experiments a progressive cu enrichment in the brine phase correlates well with depressurization prior to mineralization mass balance considerations based on analyzed fluid components and fluid phase relations indicate that brine was volumetrically minor and therefore likely stagnant but this may have prepared ore precipitation by accumulating cu stripped from ascending vapor

time scales of porphyry cu deposit formation insights from titanium diffusion in quartz porphyry dikes and hydrothermal veins from the porphyry cu mo deposit at butte montana contain multiple generations of quartz that are distinct in scanning electron microscope cathodoluminescence sem cl images and in ti concentrations a comparison of microprobe trace element profiles and maps to sem cl images shows that the concentration of ti in quartz correlates positively with cl brightness but al k and fe do not after calibrating cl brightness in relation to ti concentration we use the brightness gradient between different quartz generations as a proxy for ti gradients that we model to determine time scales of quartz formation and cooling model results indicate that time scales of porphyry magma residence are 1 000s of years and time scales from porphyry quartz phenocryst rim formation to porphyry dike injection and cooling are 10s of years time scales for the formation and cooling of various generations of hydrothermal vein quartz range from 10s to 10 000s of years these time scales are considerably shorter than the 0 6 m y overall time frame for each porphyry style mineralization pulse determined from isotopic studies at butte montana simple heat conduction models provide a temporal reference point to compare chemical diffusion time scales and we find that they support short dike and vein formation time scales we interpret these relatively short time scales to indicate that the butte porphyry deposit formed by short lived episodes of hydrofracturing dike injection and vein formation each with discrete thermal pulses which repeated over the 3 m y generation of the deposit

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

a numerical model to estimate trapping conditions of fluid inclusions that homogenize by halite disappearance abstract fluid inclusions fi that homogenize by halite disappearance are common in some geological environments and interpretation of microthermometric data from these inclusions has been limited by the lack of a model describing the pvtx relationships over the complete range of ptx conditions found in nature in this study a system of equations has been developed that can be used to estimate salinity pressure and density of fi that homogenize by halite disappearance the salinity pressure density and d p d t slope of the fi isochore are calculated as functions of liquid vapor homogenization temperature th and halite dissolution temperature tm the equations are based on a numerical model describing the isochoric pressure temperature trajectory followed by halite saturated fluids during heating the model is valid for th and tm from 100 to 600 c and for pressures along the liquid vapor halite curve to 300 mpa

assessing the geochemical and tectonic impacts of fluid rock interaction in mid crustal shear zones a case study from the intracontinental alice springs orogen central australia the reynolds anmatjira ranges central australia form part of a high grade basement terrane dissected by intensely metasomatized transpressional shear zones active during the ordovician carboniferous alice springs orogeny unlike typical retrograde structures associated with discrete fluid flow the mid crustal setting and intracontinental nature of these shear systems present significant problems for the source and ingress mechanism of the fluid involved in their rehydration to address these issues we describe two detailed traverses across deformed and metasomatized basement rocks in this region and interrogate their record of fluid rock interaction from various perspectives both traverses combine structural and petrological observations with zr in rutile and ti in quartz thermobarometry oxygen and hydrogen stable isotope analysis and major trace and rare earth element mobility trends each technique is critically evaluated for its utility in this study and its more widespread applicability to alternative field areas providing a strategic framework for the general investigation of fluid affected shear zones ultimately the integrated data sets specify pressure temperature conditions of 530 c and 4 5 kbar implying average apparent thermal gradients of 29 36 c km 1 and depths of 14 18 km other characteristic features to emerge include strongly variable element mobilities and pronounced isotopic depletion fronts consistent with the alteration effects of an externally derived non equilibrium fluid this is confirmed by calculated fluid compositions indicative of contributions from a fluid of meteoric origin with estimated 18o and d values as low as 2 3 and 59 8 respectively we propose that these surficial fluid signatures are imposed on the mid crust by the prograde burial and dehydration of hydrothermally altered fault panels produced during pre orogenic basin formation progressive fluid release with continued subsidence then leads to the accumulation of increasing fluid volumes in the vicinity of the brittle ductile transition promoting extensive hydration metasomatism and reaction softening at the locus of stress transmission from plate boundary sources the sustained injection of externally derived fluids into refractory crustal material may thus stimulate a critical reduction in the long term strength of the lithosphere providing strong impetus for the initiation and advancement of intracontinental orogenesis

two event lode ore deposition at butte usa 40ar 39ar and u pb documentation of ag au polymetallic lodes overprinted by younger stockwork cu mo ores and penecontemporaneous cu lodes abstract the ore genesis model for world class deposits of the butte mining district montana usa is deep pre main stage porphyry cu mo and overlying main stage ag zn cu zoned lode deposits both of which formed from hydrothermal fluids driven by minor volumes of rhyolitic magma the lode specific model is that hydrothermal processes diminished in intensity outward from district center along lode veins synchronously forming metal zones the accepted models are controverted by new geologic and multi method geochronologic studies the new data reveal the following sequence of events 1 thermal study of country rock indicates that the 76 9 ma butte granite cooled to 350 400 c by 4 m y after emplacement 2 five quartz porphyry rhyolite dikes were emplaced at 67 65 ma and another at 60 ma shrimp u pb into the cooled butte granite without resetting 40ar 39ar ages in country rock 3 fifty eight white mica and k feldspar samples from alteration envelopes adjacent to ag au polymetallic lodes in outer parts of the district zn rich lodes in intermediate parts and cu rich lodes in the district center yield 40ar 39ar ages of 73 70 ma for ag rich lodes 65 64 ma for cu rich lodes and complex age spectra of 69 65 ma for zn rich lodes the data show that ag au polymetallic lodes occupied cross district fractures by about 73 ma forming the greater butte mining district at 67 65 ma minor quartz porphyry dikes were emplaced into central and eastern parts of the rejuvenated fracture system but without evidence of related cupola or volcanic rocks or of thermal disturbance in the country rock at 64 5 ma overlapping hydrothermal cells formed two stockwork cu mo domes in deep parts of the fracture system at 65 64 ma and closely related to late stage stockwork cu mo activity a penecontemporaneous hydrothermal pulse formed a high sulfidation hydrothermal plume that 1 utilized the large re opened fractures to cannibalize and remobilize cu from autologous stockwork and older ag au polymetallic lodes 2 deposited the rich high sulfidation cu lodes and 3 mobilized metals from early ag au polymetallic veins in middle parts of the district transported the metals outward and redeposited them enriching early veins especially in the intermediate zn plus cu areas metals zones in lodes of the butte district are the result of an intensely focused cu rich hydrothermal plume that variably reworked the center of significantly larger 10 m y older ag au polymetallic lodes

organic geochemistry distribution and hydrocarbon potential of source rocks in the paleocene lishui sag east china sea shelf basin abstract the lishui sag one of the most promising hydrocarbon exploration areas in the east china sea shelf basin has had no major breakthroughs after its exploration and development therefore it is crucial to carry out a comprehensive assessment of this basin to illustrate the potential and distribution of source rocks in the lishui sag based on organic petrographic examinations rock eval pyrolysis gas chromatography gc and gas chromatography mass spectrometry gc ms analysis the organic geochemical characteristics and paleoenvironment of the source rocks were investigated the results imply that the kerogen type of the source rocks in the lishui sag is dominated by type iii with a small amount of type ii kerogen biomarkers show that the source rocks are characterized by a mixed origin of organic matter in a transitional environment the lower mingyuefeng e1ml lower lingfeng e1ll and yueguifeng e1y formations show higher inputs of aquatic organic matter the base limits of the total organic carbon toc values of effective source rocks were determined to be 0 9 wt in the e1m formation 1 0 wt in the e1l formation and 0 7 wt in the e1y formation based on an artificial neural network ann model and the log r method the distribution of effective source rocks in the lishui sag was illustrated source rocks in the e1ml and lingfeng e1l formations can be expected to generate mixed liquid hydrocarbons while samples from e1y formation are oil prone source rocks with normal oil and light oil potentials additionally the post mature source rocks of the e1y formation may be the origin of natural gas upon full consideration of the potential and distribution of source rocks the north part of the lingfeng uplift is the most favorable exploration zone

raman spectroscopic densimeter for pure co2 and co2 h2o nacl fluid systems over a wide p t range up to 360 c and 50 mpa abstract density of fluid inclusions is one of the most important parameters to reconstruct the p t conditions of entrapment of geo fluids co existing with microthermometry methods raman spectroscopy also became a useful tool to determine the density of co2 bearing inclusions via fermi diad splitting in this study a new co2 densimeter which takes into account the effects of temperature pressure and h2o nacl on fermi diad splitting was built from experiments using a high pressure optical cell raman spectra of co2 were collected in the range 20 to 360 c and 0 51 to 50 mpa i e a density range from 0 0057 to 1 1600 g cm 3 our results show that temperature and pressure have significant impact on density relationship with lower by up to about 0 5 cm 1 with increasing pressure and temperature at a given density on the contrary dissolved h2o nacl had no effect on the density relationship so the function defined for pure co2 system can also be applied to calculate the density of co2 h2o nacl system up to 360 c 50 mpa and 20 35 wt nacl the new densimeters presented in this study provide a useful tool to determine the pressure of co2 rich fluid inclusions all along the isochoric path for any water concentration

calibration data for simultaneous determination of p v x properties of binary and ternary co2 ch4 n2 gas mixtures by raman spectroscopy over 5 600 bar application to natural fluid inclusions abstract the p v x properties of two component fluid inclusions fis are generally determined from microthermometry data using appropriate thermodynamic models i e vx diagrams and or equations of state eos however some limitations can hamper the applicability of this technique such as the small size low density or complex composition of the analyzed fi raman spectroscopy is known as the best suited alternative method to microthermometry for the investigation of natural fis because it can provide simultaneously non destructive qualitative and possible quantitative analyses after specific calibrations the present work aims to provide calibration data to directly determine the p v x properties of binary or ternary mixtures of ch4 co2 and n2 the variation of spectral features as a function of composition and pressure or density was investigated by using raman spectroscopy coupled with an improved high pressure optical cell hpoc system and a customized heating cooling stage from our experimental data the relative raman scattering cross section rrscs of ch4 ch4 was demonstrated to be constant at 7 73 0 16 over the investigated range of pressure 5 600 bars and for any composition this parameter can thus be used for the determination of composition with an uncertainty of 0 5 mol several calibration equations were calculated for different px domains linking the fermi diad splitting of co2 or the relative variation of the ch4 peak position ch4 to the pressure or density and composition of co2 ch4 ch4 n2 and co2 n2 ch4 mixtures at 22 and 32 c the pressure and density of the fluids can henceforth be directly measured from raman spectra with an uncertainty of 20 bars and 0 01 g cm 3 respectively our calibration equations were then validated on natural fis by comparing the results obtained from raman and microthermometry we also interpreted the variation of the peak position of ch4 based on the change of intermolecular interaction finally we discussed the applicability of the obtained calibration data into another laboratory by comparing it with the data of pure co2 and ch4 published in literature a small shift between calibration curves implies a systematic error which is perhaps due to the difference in the configuration or the day to day deviation of the instruments therefore standards of well known p v x properties should be regularly measured to prevent and to correct any variation or shifting of the instrumental responses

morphological ripening of fluid inclusions and coupled zone refining in quartz crystals revealed by cathodoluminescence imaging implications for cl petrography fluid inclusion analysis and trace element geothermometry cathodoluminescence cl studies have previously shown that some secondary fluid inclusions in luminescent quartz are surrounded by dark non luminescent patches resulting from fracture sealing by late trace element poor quartz this finding has led to the tacit generalization that all dark cl patches indicate influx of low temperature late stage fluids in this study we have examined natural and synthetic hydrothermal quartz crystals using cl imaging supplemented by in situ elemental analysis the results lead us to propose that all natural liquid water bearing inclusions in quartz whether trapped on former crystal growth surfaces i e of primary origin or in healed fractures i e of pseudosecondary or secondary origin are surrounded by three dimensional non luminescent patches cross cutting relations show that the patches form after entrapment of the fluid inclusions and therefore they are not diagnostic of the timing of fluid entrapment instead the dark patches reveal the mechanism by which fluid inclusions spontaneously approach morphological equilibrium and purify their host quartz over geological time fluid inclusions that contain solvent water perpetually dissolve and reprecipitate their walls gradually adopting low energy euhedral and equant shapes defects in the host quartz constitute solubility gradients that drive physical migration of the inclusions over distances of tens of m commonly up to several mm rarely inclusions thus sequester from their walls any trace elements e g li al na ti present in excess of equilibrium concentrations thereby chemically purifying their host crystals in a process analogous to industrial zone refining non luminescent patches of quartz are left in their wake fluid inclusions that contain no liquid water as solvent e g inclusions of low density h2o vapor or other non aqueous volatiles do not undergo this process and therefore do not migrate do not modify their shapes with time and are not associated with dark cl zone refined patches this new understanding has implications for the interpretation of solids within fluid inclusions e g ti and al minerals and for the elemental analysis of hydrothermal and metamorphic quartz and its fluid inclusions by microbeam methods such as la icpms and sims as ti is a common trace element in quartz its sequestration by fluid inclusions and its depletion in zone refined patches impacts on applications of the ti in quartz geothermometer

a model for the evolution of brines in salt from the lower salado formation southeastern new mexico fluid inclusions were collected from a bedded salt horizon in the lower permian salado formation in the delaware basin southeastern new mexico the sampling horizon at a depth of approximately 645 meters consists primarily of recrystallized halite with thin layers of anhydrite other trace minerals dispersed throughout the salt include quartz polyhalite gypsum k feldspar magnesite and clays large fluid inclusions up to several mm on an edge are common in the halite in addition bands of microscopic 10 m fluid inclusions are present as primary chevron structures in fragments of unrecrystallized salt we sampled 109 large inclusions by individual extraction of the fluids which were analyzed for ca mg k na cl br and so4 the chemistry of the inclusion fluids and the associated mineralogy suggest that these brines represent permian seawater that has undergone evaporation and subsequent modification by diagenetic reactions dominated by the alteration of calcium sulfate to polyhalite and magnesite formation the range of fluid inclusion compositions suggests a significant departure from a simple seawater evaporation model other brines from the same horizon in the salado formation were sampled and analyzed for the same elements as the fluid inclusions and differed significantly from them primarily by the depletion of mg relative to k the association of these brines with argillaceous and or anhydritic halite containing a suite of authigenic minerals quartz magnesite and mg rich clays suggests that these are intergranular brines with compositions determined over a much longer time scale than that required by the fluid inclusions the principal reactions affecting intergranular brine chemistry are dehydration of gypsum dewatering of detrital clays and uptake of mg during clay diagenesis overall the observed variation in brine compositions implies that if large scale hydrologie circulation is occurring in the salado halite the time scale is limited by the rate required for low temperature silicate diagenesis

hydrothermal alteration of oxygen isotope ratios in quartz phenocrysts kidd creek mine ontario magmatic values are preserved in zircon zircons from rhyolites hosting the kidd creek volcanogenic massive sulfide deposit preserve magmatic oxygen isotope ratios 18 o 5 4 0 3 n 11 that are indistinguishable from average values of other plutonic and volcanic rocks of the superior province oxygen isotope ratios of petrographically pristine primary quartz phenocrysts however are greatly elevated in 18 o and heterogeneous 18 o 14 2 to 16 1 such phenocrysts are not a good monitor of magmatic processes the presence of healed microcracks in quartz phenocrysts as seen in cathodoluminescence images and the variability of quartz oxygen isotope ratios suggest that recrystallization is the process of 18 o elevation in contrast to the variability of quartz the 18 o zircon values do not vary regardless of the degree of magnetic susceptibility the 18 o values of zircon are interpreted to reflect the primitive magmatic oxygen consistent with the rhyolite geochemistry for magmas derived by partial melting of a tholeiitic source our data show that the 18 o values of quartz and whole rock at kidd creek are a good monitor of hydrothermal exchange and are 5 higher than the magmatic value that is preserved in zircon due to its refractory nature

magmatic hydrothermal activity in the shuteen area south mongolia the shuteen area is located in the gurvansaikhan island arc terrane of south mongolia it contains a large domain of intensely developed silicic and advanced argillic alteration that has strongly affected the adakitic volcanoplutonic shuteen complex the local occurrence of low grade copper mineralization within porphyritic intrusive rocks is indicative of porphyry style mineralization hydrothermal quartz veins host gold mineralization locally the results of scanning electron microscope cathodoluminescence imaging and fluid inclusion microthermometry indicate that the veins and altered rocks at shuteen were produced by multiple hydrothermal events the occurrence of co2 inclusions in quartz from granitoids and the 34s values obtained for sulfide and sulfate within the hydrothermal breccias provide evidence of the involvement of magmatically derived fluids in the early stages of the shuteen magmatic hydrothermal system inferred to be sourced from a porphyry style intrusive center late stage fluids produced abundant barren quartz veins and clay alteration assemblages the weak mineralization and widespread alteration in the shuteen complex are typical of lithocaps found in high level porphyry copper gold molybdenum and high sulfidation epithermal districts the presentday erosion level at shuteen is relatively shallow implying that economic porphyry style mineralization may exist at depth within or beneath the shuteen lithocap

some observations on the origins of large volumes of carbon dioxide accumulations in sedimentary basins large volumes of carbon dioxide i e up to 90 v v have been encountered in sedimentary basins from various geological settings but their origins remain enigmatic evidence from carbon and noble gas isotope analyses indicate a variety of interpretations for the origins of the co2 including mantle degassing metamorphic reactions or magmatic processes the formation of large accumulations of large volumes of co2 in sedimentary basins is discussed with specific reference to published data from the pannonian basin hungary the cooper eromanga basin australia and the south viking graben north sea these basins have occurrences of large volumes i e over 15 v v of isotopically heavy carbon dioxide thought to be of inorganic origin and although they differ somewhat in terms of sedimentary fill all have major structural features close to the gas accumulations the available geochemical data are currently neither sufficient to confirm the specific origin s of the co2 e g mantle derived carbonate metamorphism nor unscramble co2 mixed from two or more sources ongoing studies especially those involving noble gas analyses should provide fuller answers

the chemistry of quartz in granitic pegmatites of southern norway petrogenetic and economic implications trace element concentrations in quartz from 188 granitic pegmatites in the froland and evje iveland pegmatite fields southern norway have been determined to establish exploration targets for high purity quartz and to gain a better understanding of the genesis of pegmatites hosting these deposits both pegmatite fields were formed during the sveconorwegian grenvillian orogeny 1145 900 ma at the western margin of the fennoscandian shield in situ raster analyses within single quartz crystals were undertaken by laser ablation inductively coupled plasma mass spectrometry la icp ms spot size 75 m to assess levels of lattice bound impurities rather than mineral and fluid inclusions that are relatively easily removed during high purity quartz processing quartz in the froland pegmatites has relatively pure and homogeneous compositions containing 46 24 gg 1 al 8 3 gg 1 ti 1 4 0 8 gg 1 ge and 11 7 gg 1 li the ti in quartz geothermobarometer gives an average pegmatite crystallization temperature of 537 39 c temperature estimates are highest along the northwestern margin of the pegmatite field 550 c whereas the most differentiated pegmatites occur toward the northeast the area of greatest economic potential for high purity quartz lies just north of the central part of the field where individual pegmatites contain 1 million metric tons mt quartz with low average trace element contents of 67 11 gg 1 from mineral chemical criteria and a range of other geologic factors we propose that pegmatite melts in the froland field were generated by fluid present crustal melting at about 1060 ma in zones of localized high strain deformation during progressive thrusting along the porsgrunn kristiansand fault zone quartz in the evje iveland pegmatites has more variable compositions with 69 57 gg 1 al 19 11 gg 1 ti 2 3 1 8 gg 1 ge and 7 5 gg 1 li from its ti content it crystallized at temperatures of 613 70 c the regional spatial distribution of ti in quartz temperatures appears irregular mainly due to the scattered distributions of chemical evolved pegmatites with amazonite cleavelandite replacement zones which show crystallization temperatures down to 442 c quartz from the evje iveland pegmatites is unlikely to be of current economic interest due to its moderate to high trace element contents heterogeneous chemistry and low volume the evje iveland pegmatites show no apparent genetic link to a granite intrusion instead they probably formed as a result of partial melting at the depth of their amphibolite country rocks at around 910 ma this is related to a regional low pressure high temperature metamorphic event at about 930 to 920 ma

dissolution of salt on the east flank of the permian basin in the southwestern u s a abstract hydrogeologic studies prove that natural dissolution of bedded salt occurs at shallow depths in many parts of the permian basin of the southwestern u s a this is especially well documented on the east side of the basin in study areas on the cimarron river and elm fork in western oklahoma and on the red river in the southeastern part of the texas panhandle four requirements for salt dissolution are 1 a deposit of salt 2 a supply of water unsaturated with respect to nacl 3 an outlet for removal of brine and 4 energy to cause water to flow through the system the supply of fresh groundwater in the region is recharged through permeable rocks alluvium terrace deposits karstic features and fractures groundwater dissolves salt at depths of 10 250 m and the resulting brine moves laterally and upward under hydrostatic pressure through caverns fractures in disrupted rock and clastic or carbonate aquifers until it reaches the land surface where it forms salt plains and salt springs in many areas salt dissolution produces a self perpetuating cycle dissolution causes cavern development followed by collapse and subsidence of overlying rock then the resulting disrupted rock has a greater vertical permeability that allows increased water percolation and additional salt dissolution

porphyry to epithermal transition in the altar cu au mo deposit argentina studied by cathodoluminescence la icp ms and fluid inclusion analysis the middle to late miocene altar porphyry cu au mo deposit located in the andean main cordillera of san juan province argentina is characterized by the superposition of multiple vein generations consisting of both porphyry type and high sulfidation epithermal style alteration and mineralization we constrain the physical and chemical evolution of the hydrothermal fluids that formed this deposit based on description and distribution of vein types scanning electron microscopy cathodoluminescence cl imaging trace elements in quartz veins and fluid inclusion microthermometry quartz cl textures and trace elements chiefly li al ti and ge differentiate among quartz generations precipitated during different mineralization and alteration events early quartz chalcopyrite pyrite veins and quartz molybdenite veins a and b veins show considerable complexity and were commonly reopened and some underwent quartz dissolution early quartz chalcopyrite pyrite veins a veins are dominated by equigranular bright cl quartz with homogeneous texture most of these veins contain higher ti concentrations than any other vein type average 100 ppm and have low to intermediate al concentrations 65 448 ppm quartz molybdenite b veins and chlorite rutile hematite c veins veins contain quartz of intermediate cl intensity that commonly shows growth zones with oscillatory cl intensity quartz from these veins has intermediate ti concentrations 20 ppm and al concentrations similar to those of a veins quartz from later quartz pyrite veins with quartz muscovite tourmaline halos d veins has significantly lower cl intensity low ti 15 ppm and elevated al concentrations up to 1 000 ppm and typically contains euhedral growth zones late veins rich in sulfides and sulfosalts show cl textures typical of epithermal deposits dark cl quartz crustiform banding and euhedral growth zones quartz from these veins typically contains less than 5 ppm ti and al li and ge concentrations are elevated relative to other vein types based on experimentally established relationships between ti concentration in quartz and temperature the decrease in ti content in successively later quartz generations indicates that the temperature of the hydrothermal fluids decreased through time during the evolution of the system vein formation at altar occurred at progressively lower pressure shallower paleodepth and lower temperature under lithostatic pressures the magma supplied low salinity aqueous fluids at depths of 6 to 6 8 km pressures of 1 6 1 8 kbar and temperatures of 670 to 730 c first quartz generation of early quartz chalcopyrite pyrite veins this parental fluid episodically depressurized and cooled at temperatures and pressures below the brine vapor solvus quartz molybdenite veins precipitated from fluids at temperatures of 510 to 540 c and pressures of 800 to 1 000 bars corresponding to depths of 3 to 3 7 km under lithostatic pressures further cooling of hydrothermal fluids to temperatures between 425 and 370 c under hydrostatic pressures of 200 to 350 bars produced pyrite quartz veins and pervasive quartz muscovite tourmaline and illite alteration that overprinted the early hydrothermal assemblages late veins rich in sulfides and sulfosalts that overlapped the deep and intermediate high temperature veins formed from fluids at temperatures of 250 to 280 c and pressures of 20 to 150 bars the epithermal siliceous ledges formed from low temperature fluids 230 c at hydrostatic pressures of 100 bars corresponding to depths of 1 km

genesis of the xiaolonghe quartz vein type sn deposit sw china insights from cathodoluminescence textures and trace elements of quartz fluid inclusions and oxygen isotopes abstract quartz textures revealed by scanning electron microscope cathodoluminescence sem cl images suggest that quartz in the xiaolonghe sn deposit formed in at least three fluid episodes quartz q1 in the pre ore silicification zone has homogeneous texture high cl intensity and high ti content 19 53 ppm fluid inclusions hosted in q1 are vapor rich v1 type and homogenized as supercritical fluid at 570 c quartz q2 in the syn ore topaz cassiterite quartz veins has lower cl intensity and is characterized by euhedral growth zones with lower ti content 1 3 12 ppm fluid inclusions hosted in q2 topaz and cassiterite are liquid rich fluid inclusions of moderate salinity 15 wt nacl equiv l1 type which homogenized at 423 c the post ore quartz q3 closely associated with sericitization of topaz generally crosscuts q2 and has dark cl intensity and much lower ti concentration the upper limits of t p conditions of pre ore and syn ore stage are constrained by the intersection of nacl h2o fluid inclusion isochores and ti in quartz isopleths and the lower limits are based on microthermometry results of fluid inclusions combined with the 18ofluid value 8 3 of q1 it indicates that the pre ore supercritical fluid was directly exsolved from a granitic magma at t 570 600 c and p 0 70 0 77 kbars corresponding to a maximum depth of 2 8 km under lithostatic pressure the syn ore subcritical fluid 8 0 18ofluid 6 3 mixed with some meteoric water was under 423 450 c 0 32 0 45 kbars the transition from the pre ore supercritical fluid to the syn ore subcritical fluid indicates boiling condition probably at 512 c 0 62 kbars which was likely caused by hydraulic fracturing under high pressure both the fluid boiling and fluid mixing contribute to the cassiterite precipitation in xiaolonghe sn deposit in the post ore stage the coexisting s type and v2 type fluid inclusions in q3 indicates a second fluid boiling at 269 c 0 05 kbars which was probably caused by decompression due to rapid denudation of the overlain strata the low salinity 5 5 wt nacl equiv l2 type fluid inclusions hosted in fluorite homogenized at 199 c and

tracking meteoric infiltration into a magmatic hydrothermal system a cathodoluminescence oxygen isotope and trace element study of quartz from mt leyshon australia the oxygen isotope and trace element composition of hydrothermal quartz has been integrated with scanning electron microscope cathodoluminescence sem cl images and fluid inclusion properties to track fluid sources and hydrothermal processes in the mt leyshon an deposit australia oxygen isotope and trace element data were collected on parallel traverses across the same quartz sections using secondary isotope mass spectrometry sims and laser ablation inductively coupled plasma mass spectrometry la icp ms respectively with sem cl images obtained before analysis for petrographic context over the 280 to 650 degrees c quartz precipitation range suggested by fluid inclusion microthermometry delta o 18 quartz varies from 0 0 to 14 4 o corresponding to a wide range of equilibrium delta o 18 fluid values from 6 1 to 10 2 o vs v smow the delta o 18 quartz signature varies systematically among distinct sem cl quartz generations both within and between samples and can be correlated with variations in temperature and fluid composition but is independent of intra generational oscillatory zoning in contrast al and li concentrations correlate broadly with cl intensity in oscillatory quartz whereas their concentration is unpredictable in sealed fractures and overgrowths concentrations of b mg na p cl k ti mn fe ge and sn are independent of al li and oscillatory cl features but ti correlates with quartz precipitation temperature although no systematic correlation between delta o 18 quartz and trace element concentrations was found complementary patterns exist in narrow overgrowths of low delta o 18 quartz similar to 0 o and high al g 10 000 ppma these quartz zones likely formed during the incursion of o 18 depleted meteoric water into the magmatically dominated mt leyshon hydrothermal system we interpret the highest al concentrations as the result of high quartz precipitation rates triggered by depressurisation of the hydrothermal cell the decoupling of oxygen isotope and trace element patterns in quartz leads to the suggestion that 1 under most circumstances temperature and fluid chemistry dominate delta o 18 quartz and 2 the trace element record and in particular al and li is influenced by the superimposed effects of quartz precipitation rate c 2007 elsevier b v all rights reserved

scanning electron microscope cathodoluminescence analysis of quartz reveals complex growth histories in veins from the butte porphyry copper deposit montana scanning electron microscope cathodoluminescence sem cl analysis of quartz reveals textures that cannot be observed using optical microscopy or backscattered electrons these cryptic textures yield insight into timing and physical conditions of quartz growth especially in environments with multiple quartz precipitation events hydrothermal quartz from quartz sulfide veins in the porphyry copper deposit in butte montana was analyzed by sem cl revealing the following textures euhedral growth zones wide nonluminescing bands that cut across multiple quartz grains rounded luminescent quartz grain cores with euhedral overgrowths nonluminescing splatters of quartz connected by networks of cobweb like nonluminescing quartz in otherwise luminescent quartz concentric growth zones and wide nonluminescent grain boundaries these textures indicate that many veins have undergone fracturing dilation growth of quartz into fluid filled space quartz dissolution and recrystallization of quartz precipitation and dissolution textures indicate that early quartz molybdenite veins formed as a result of pressure fluctuations between lithostatic and hydrostatic at high temperatures and later pyrite quartz veins formed near hydrostatic pressure in response to temperature decrease through and beyond the field of retrograde quartz solubility

silica diagenesis in the lower paleozoic wufeng and longmaxi formations in the sichuan basin south china implications for reservoir properties and paleoproductivity abstract silica diagenesis is one of the most important aspects of black shale diagenesis and critically controls the reservoirs properties of black shales three stratigraphic sections of the wufeng and longmaxi formations in the sichuan basin along a proximal to distal transect were investigated to study quartz types and their silica sources as well as their influences on reservoirs properties including rock mechanical properties and porosity preservation six types of quartz including detrital quartz recrystallized radiolaria siliceous fossil fragments microcrystalline quartz quartz overgrowth and hydrothermal quartz veins were identified based on their occurrences and morphologies under the petrographic microscope and scanning electron microscope and cathodoluminescence color and intensity original biogenic silica now exists as recrystallized radiolaria and microcrystalline silica in the mudstone matrix and follows systematic distribution patterns both laterally and stratigraphically the biological origin of this silica component is supported by the presence of recrystallized radiolaria with preserved spines preservation of ghosts of the central capsule serrated edges reflecting the spherical lattices of the outer shell and in addition preserved sponge spicules a further source of silica for microcrystalline quartz formation was silica released in the course of clay mineral smectite to illite transformation the different types of quartz make different contributions to the reservoir properties of shales with microcrystalline quartz having the most important impact microcrystalline quartz enhances the rock mechanical properties of shales and protects initial porosity from mechanical compaction through a rigid framework of interconnected diagenetic silica grains pores between microcrystalline quartz grains are shielded from complete mechanical compaction and provide space for accumulation of bitumen and oil later in burial history subsequently these pore filling organic matter develop secondary organic nanopores at higher thermal maturity although biogenic silica content has been used as a paleoproductivity proxy the method used to calculate it is based on questionable assumptions and model parameters need to be fine tuned for a given shale succession on the basis of petrographic observations in addition the commonly observed positive correlation between total organic carbon toc and biogenic silica is invalid for very low sedimentation rates and extremely high concentrations of biogenic silica from low to extremely high biogenic silica content in organic rich sediments a parabolic relationship between toc and biogenic silica should be common

magmatic hydrothermal evolution of the yuanzhuding porphyry cu mo deposit south china insights from mica and quartz geochemistry abstract the yuanzhuding porphyry cu mo deposit located in the southern section of the qinzhou hangzhou belt is characterized by successive generations of quartz bearing veins with complicated crosscutting relationships multiple analytical methods have been applied to different mica types and quartz bearing veins to reveal the evolution history of the yuanzhuding porphyry system four types of micas have been identified in the yuanzhuding porphyry cu mo deposit including magmatic biotite bt i metamorphic biotite bt ii hydrothermal biotite bt iii and hydrothermal sericite ser based on detailed petrological observations all three types of biotite belong to the mg biotite group but can be compositionally distinguished whereas ser lies in the transition zone between li phengite and li muscovite generally decreasing crystallization temperatures with increasing distances from the center of the porphyry have been revealed in bt ii and bt iii based on their compositional variations documenting the outward cooling trends of the yuanzhuding porphyry system early quartz bearing veins with potassic alteration are characterized by granular quartz with homogeneous cl textures in combination with their wavy vein walls which indicate the host rock was ductile during vein formation we infer that they were formed under dominantly lithostatic pressure late quartz bearing veins with sericitic alteration are typically euhedral quartz with growth zones of oscillating cl intensity and they are inferred to be formed under dominantly hydrostatic pressure intersection of fluid inclusion isochores with ti in quartz isopleths revealed that early quartz veins with potassic alteration located close to the ore forming porphyry were formed at up to 575 c late quartz veins with sericitic alteration were formed at 310 c formation depth of the yuanzhuding porphyry deposit is inferred to be 5 3 km hydrogen and oxygen isotopes of bt iii and quartz indicate that the ore forming fluid was mainly magmatic fluid the fluid pressure was high enough to remain stable in single phase through the entire fluid evolution history all fluid inclusions are vapor liquid inclusions the fluid salinity and the cl fugacity remained constantly low which may have limited the efficiency of cu extraction and transportation the hornfels host significant amounts of bt ii and may have served as a reservoir of ferrous iron to reduce the oxidized ore forming fluid and generate reduced sulfur effective metal precipitation occurred in the yuanzhuding porphyry system owing to the coexistence of the generation of reduced s2 and the drop of metal solubility caused by the decrease of fluid temperature

ti resetting in quartz during dynamic recrystallization mechanisms and significance the ubiquity of quartz in continental crust and the involvement of sio 2 in multiple metamorphic processes such as reactions fluid flux and solution transfer processes makes quartz an obvious choice for reconstructing prograde metamorphic conditions in various rock types recent studies have shown the usefulness of analyzing ti distribution in quartz to constrain pressure temperature relative time deformation p t t d in metamorphosed tectonites new high precision single crystal x ray diffraction volume constraints on ti doped and chemically pure quartz provide further evidence for substitution of ti 4 for si 4 in the tetrahedral site in quartz with resultant lattice strain on the structure recent applications of the ti in quartz thermobarometer to dynamically recrystallized quartz have identified recrystallized subgrains that contain lower ti concentrations ti than their host porphyroclasts in addition ti are lower than expected for the temperatures of recrystallization atomistic simulations that estimate energetic perturbations resulting from ti incorporation into the quartz lattice indicate that significant increases in strain energy occur only at very high ti the strain energy increase is negligible for ti typical of quartz grown under mid crustal conditions this suggests that lattice strain rarely provides an appreciable driving force for ti loss from quartz instead it appears that subgrain boundaries and dislocation arrays migrating through recrystallizing quartz crystals can promote localized re equilibration thermodynamically regulated by the composition of the intergranular medium typically undersaturated in ti it therefore appears that analyses from dynamically recrystallized quartz cannot be meaningfully interpreted until methods are developed that can account quantitatively for the reduction of ti resulting from crystal plastic flow

multiphase natural gas migration and accumulation and its relationship to diapir structures in the df1 1 gas field south china sea abstract the dongfang1 1 df1 1 gas field is the largest commercial gas field yet discovered in the yinggehai basin south china sea the gas reservoirs in the field are normally pressured pliocene shallow marine facies fine grained sandstones and the main source rocks are highly over pressured miocene mudstones and shales the natural gases in the reservoirs consist mainly of hydrocarbon gas co 2 and n 2 geochemical data for the natural gases show that the hydrocarbon rich gases except for a small amount of biogas were derived from these source rocks distributed within over pressured zones but gases rich in co 2 mainly originate from the thermal decomposition of miocene calcareous shales and pre tertiary carbonates at higher temperature fluid inclusion data for the reservoirs were used together with the regional geology distribution of different types of reservoirs and the evolution of diapir structures to determine the episodes of gas migration and accumulation in the df1 1 gas field we believe that the field was formed by four episodes of gas migration and accumulation fluid paleopressure simulation software designed and developed by cnooc china limited was used to simulate the paleopressure history of the strata at the top of the present day high pressure zone a depth of 2800 m in the df1 1 gas field it predicts that the first episode occurred before about 2 ma the second and the third episodes between 2 and 0 5 ma and that the co 2 rich gases migrated into the reservoirs after 0 5 ma the formation and evolution of diapir structures in the yinggehai basin had an important influence on the migration and accumulation of natural gases in the df1 1 gas field rapid deposition gas generation in the source rocks and thermal expansion of pore fluids caused over pressuring in the miocene shales in the center of the depression this over pressuring together with active faulting formed diapir structures during 5 0 5 ma the faults and fractures related to the diapir structures provided a pathway for gas vertical migration from the deep source rocks into the df1 1 reservoirs and controlled the geological distribution of different types of natural gases on this basis a model for gas migration and accumulation is suggested for the df1 1 gas field

new evidence for 250 ma age of halotolerant bacterium from a permian salt crystal the purported oldest living organism the spore forming bacterium virgibacillus sp perm ian strain 2 9 3 was recently cultured from a brine inclusion in halite of the 250 ma permian salado formation however the antiquity of virgibacillus sp 2 9 3 has been chal lenged it has been argued that the halite crystal and the fluid inclusion from which the bacterial spores were extracted may be younger than the permian salado salts here we report that brine inclusions from the same layer of salt that housed virgibacillus sp 2 9 3 are composed of evaporated late permian seawater that was trapped in halite cement crys tals precipitated syndepositionally from shallow groundwater brines at temperatures of 17 37 8c these results support the 250 ma age of the fluid inclusions and by inference the long term survivability of microorganisms such as virgibacillus sp 2 9 3

pressure fluctuations phase separation and gold precipitation during seismic fracture propagation gold mineralization at croagh patrick western ireland occurs in quartz veins associated with three synchronous oblique tensile shear systems the veins evolved by progressive thickening of isolated en echelon lensoid tensile fractures that show a power law relation between their length and thickness a change in power law exponent marks the linking of the en echelon arrays by large oblique tensile veins fluid inclusion data show that gold was deposited due to unmixing of an h 2 o co 2 nacl fluid at 320 240 c and 160 30 mpa primarily due to decreases in fluid pressure evidence for phase separation is only observed in the large linking veins and is abundant close to intersections of the vein arrays these sites are where high gold grades occur the distribution of gold is believed to reflect both spatial and temporal variations in fluid pressure fluctuation during seismic fracture propagation controlled by the vein growth mechanism and zones of maximum dilation

fluid inclusion petrography abstract a procedure of fluid inclusion studies is proposed with emphasis on the criteria of selecting fluid inclusions for detailed microthermometry and spectroscopic analysis an overview of descriptive and genetic classifications of fluid inclusions in single crystals and in massive rocks is given with the intention of further differentiating the commonly used terms primary and secondary fluid inclusions some principles of fluid inclusion modification are explained cathodoluminescence cl studies of quartz with the optical high power cl microscope and the electron microprobe provided with a cl detector are an important help in fluid petrography cl textures are subdivided in primary growth textures and a wide variety of secondary microtextures which are in part induced by fluid inclusions the latter is grouped in textures indicative of local lower crystal order increasing defect structures and microtextures indicative of local quartz healing reduction of the defect structures microtextures showing the genetic relationship between fluid inclusions and the host mineral provide information about the possible post entrapment changes of fluid inclusions and therewith testify their geological relevance

charge history of co2 in lishui sag east china sea basin evidence from quantitative raman analysis of co2 bearing fluid inclusions abstract the accumulation of carbon dioxide in natural gas reservoirs is common and co2 gas fields have been widely discovered in the world in the last decades three co2 pools were discovered in lishui sag east china sea basin geochemical proxies indicate that co2 in these gas reservoirs is dominated by mantle source volcano degassing although three volcanic events occurred in the formation of these reservoirs the co2 charging period is not clear in this study pure co2 co2 rich and h2o rich fluid inclusions were found in healed micro fractures and overgrowth zones of quartz in the reservoir of lishui sag the composition and density of two h2o rich inclusions two co2 rich inclusions and twenty three pure co2 inclusions were determined by raman quantitative analysis the burial depth of co2 fluid inclusion assemblages fia can be determined by the trapping pressure constrained from raman quantitative analysis and thermodynamic models the combination of c he isotope analyses pt entrapment conditions of co2 bearing inclusions feature of fault activity and simulation of burial history permits to assign periods of co2 fluid activity the low density 0 15 g cm 3 co2 gas inclusions recorded an early period of co2 activity eruption to be related with the late paleocene volcanic event the mid density 0 45 g cm 3 and high density 0 75 g cm 3 co2 inclusions were assigned to the miocene volcanic event and to a later co2 charging event during pliocene

geochemistry and origins of natural gases in the yinggehai and qiongdongnan basins offshore south china sea abstract four gas fields and a number of gas bearing structures have been discovered in the yinggehai and qiongdongnan basins offshore south china sea chemical and isotopic data indicate the presence of at least three genetic groups of gases in these basins biogenic gas thermogenic gas and gases with mixed origin thermogenic gases produced from the yacheng field are characterized by relatively high contents of benzene and toluene relatively low 13c values of toluene and high abundance of bicadinanes and oleanane in the associated condensates showing good correlation with the coal bearing sequence of the yacheng formation in the qiongdongnan basin in contrast the gases from the df1 1 and ld gas fields contain high amounts of n2 and co2 low to moderate amounts of benzene and toluene with relatively high 13c values of toluene these characteristics correlate well with the miocene neritic shales in the yinggehai basin analyses on potential source rock samples indicate excellent gas source potential for both the coal bearing sequence in the yacheng formation and the miocene neritic shales containing type iii ii2 kerogens as the result of recent rapid subsidence and sedimentation high temperature and overpressure systems are well developed in the yinggehai and qiongdongnan basins the rapid heating resulted in advanced maturation of organic matter deposited in normally pressured and overpressured strata whereas the strongly overpressured systems led to retarded organic matter maturation postponing the time when the source rocks reached peak gas generation results of 1 d modeling indicate that the coal bearing yacheng formation in the yacheng sag reached peak gas generation during mid miocene pliocene time after the deposition of upper oligocene to lower miocene reservoir rocks the lower mid miocene marine shales reached their peak gas generation stage during the pliocene quaternary in the central yinggehai basin supplying abundant gases to charge the pliocene reservoirs more importantly focused episodic gas migration significantly increased the hydrocarbon expulsion efficiencies of source rocks and thus provided favorable conditions for the accumulation of large amounts of gases in the diapiric structures in a very short geological time the gas source relationship for the yacheng field suggests dominantly short distance gas migration and thus strong source facies controls on the geographic distribution of gas fields within the qiongdongnan basin

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

trace elements and cathodoluminescence of quartz in stockwork veins of mongolian porphyry style deposits the combination of scanning electron microscope cathodoluminescence cl fluid inclusion analysis and high resolution electron probe microanalysis of al ti k and fe in vein quartz has yielded results permitting a greater understanding of the complex mineralisation of the central oyu tolgoi and zesen uul porphyry style deposits southern mongolia these data demonstrate the relationship between quartz precipitation dissolution and ore deposition as the mineralising fluid chemistry changed through time four major quartz generations are identified in the a type veins from the stockworks of both the central oyu tolgoi oti to otiv and zesen uul deposits zui to zuiv despite differences in the associated alteration and mineralisation style the observed cl textures and trace element signatures of the quartz generations are comparable between deposits the oti and zui stage formed both the primary network of a type veins and pervasive silicification of the host rock using the ti in quartz geothermometer crystallisation temperatures for oti and zui of between 598 c and 880 c are indicated the main stage of sulphide mineralisation was accompanied by the dissolution of pre existing quartz oti and zui and precipitation of a weakly luminescent generation of quartz otii and zuii with a low ti content reflected in a calculated temperature drop from approximately 700 c to 340 c in central oyu tolgoi and 445 c in zesen uul otii and zuii stage quartzes show high and variable al concentrations the next stage of quartz in both deposits otiii and zuiii forms a fine network of veins in cracks formed in pre existing quartz otiii and zuiii quartz contain measurable fluid inclusions of moderate salinity 3 17 1 wt nacl eq entrapped in the temperature range 256 c to 385 c otiii and zuiii are not related to any sulphide mineralisation the final otiv and zuiv stages are characterised by quartz calcite micro breccias that penetrate the a type veins based on the calculated entrapment temperatures the otiv zuiv stage crystallised between 212 c and 335 c and the quartz is characterised by elevated but variable al and fe contents the cl and trace element signatures of the oti to otiii and zui to zuiii stages of the two mongolian porphyries show similar features to those observed in porphyry style deposits from other regions this suggests that a common sequence of quartz crystallisation occurs during the formation of early veins in many porphyry copper systems

synthetic fluid inclusions xvii pvtx properties of high salinity h2o nacl solutions 30 wt nacl application to fluid inclusions that homogenize by halite disappearance from porphyry copper and other hydrothermal ore deposits fluid inclusions that homogenize by disappearance of the halite crystal after the vapor bubble has disappeared have been reported from a wide range of ore forming systems while this inclusion type is most commonly observed in porphyry copper and similar magmatichydrothermal ore deposits they have also been reported from iron oxide copper gold iocg mississippi valley type orogenic lode greenstone gold massive sulfide unconformity u and mantotype deposits as well as from non ore associated granitoids and oceanic crust the lack of experimental data to interpret microthermometric data from these inclusions combined with poor petrographic characterization of inclusion origin has led to a wide range of inferred pt trapping conditions for the inclusions the relationship between liquid vapor homogenization temperature thl v halite dissolution temperature tmhalite and pressure has been determined using synthetic h2o nacl fluid inclusions that homogenize by halite disappearance the experimental data cover the range thl v 150 to 500 c and tmhalite 275 to 550 c an empirical equation describing the relationship between pressure thl v and tmhalite has been developed to estimate formation pressures from microthermometric data and is valid from pressures along the liquid vapor halite curve to 300 mpa a detailed literature review reveals that the results of this study cannot be applied retroactively to estimate pressures of previously reported inclusions that homogenize by halite dissolution for several reasons first most workers have not collected and reported the data in a manner that allows one to determine if the inclusions have trapped a single homogeneous phase and have not leaked or changed volume following trapping thus it is not possible to determine if the inclusions show consistent microthermometric behavior within a group of coeval inclusions additionally many published studies provide only summaries of results from numerous samples or present the data graphically precluding application of our results to individual inclusions however based on our review it appears that much of the published data for inclusions that homogenize by halite dissolution represent inclusions that have either trapped a halite crystal along with the liquid or have reequilibrated by necking and or stretching results from this study have been used to estimate minimum formation pressures for inclusions from the ditrau alkaline massif transylvania romania the musoshi stratiform copper deposit zaire the bismark skarn deposit northern mexico the naica chimneymanto deposit mexico the questa porphyry molybdenum deposit new mexico and the bingham canyon porphyry cu mo deposit utah in each case pressures estimated using results from the present study are in good agreement with previous pressure estimates however in some cases estimated pressures both our estimates as well as those of other authors appear to be unreasonably high based on the geologic setting at the time of formation these results highlight the currently limited understanding concerning pressures depths of ore formation

use of hyperspectral images in the identification and mapping of expansive clay soils and the role of spatial resolution hyperspectral images were acquired along the front range urban corridor in colorado to determine the feasibility of identification and mapping of expansive clay soils with two high snr imaging spectrometers swelling soils are a major geologic hazard and cause extensive damage world wide every year the cost of postconstruction mitigation and standard engineering soil tests for creation of regional maps are immense smectite is the clay mineral group that has the greatest swelling potential and is responsible for most of the severe swelling soil damage observed in colorado data sets were acquired from 1997 to 1999 with the airborne visible infrared imaging spectrometer aviris and the hyperspectral mapper hymap using a matched filtering algorithm maps of exposed clay material were produced despite a strong vegetation cover among those exposures spectral discrimination and identification of variable clay mineralogy such as smectite smectite illite and kaolinite in decreasing order of swelling potential hazard was possible the comparison of the results from the two sensors showed that higher spatial resolution provided purer image endmembers in more heterogeneous sites but did not exhibit more endmembers and did not identify new natural outcrops that a lower spatial resolution data set would miss in a homogeneous terrain however an increase in the signal to noise ratio snr of the instrument by pixel summation made possible the identification of low reflectance exposures this work demonstrates that using recent instruments and well established methodologies imaging spectrometry can be of practical help for the detection and mapping of expansive clays

open fissure mineralization at 2600 m depth in long valley exploratory well california insight into the history of the hydrothermal system abstract long valley exploratory well drilled into the resurgent dome at long valley caldera california to explore the potential of geothermal power in an active magmatic system achieved temperatures of only ca 100 c at 2500 3000 m depth well below the range expected atop an active magma chamber open fissures encountered at 2600 m depth are coated by mm sized idiomorphic quartz crystals with first and second order growth discontinuities specific growth defects indicating rapid crystallization reflect sudden changes in sio 2 supersaturation fluid inclusions contain low salinity 0 5 wt nacl and low co 2

copper deposition during quartz dissolution by cooling magmatic hydrothermal fluids the bingham porphyry abstract scanning electron microscope cathodoluminescence imaging is used to map successive generations of fluid inclusions in texturally complex quartz veinlets representing the main stage of ore metal introduction into the porphyry cu au mo deposit at bingham utah following conventional fluid inclusion microthermometry laser ablation inductively coupled plasma mass spectrometry la icpms is applied to quantify copper and other major and trace element concentrations in the evolving fluid with the aim of identifying the ore forming processes textures visible in cathodoluminescence consistently show that the bulk of vein quartz q1 characterized by bright luminescence crystallized early in the vein history cu fe sulfides are precipitated later in these veins in a microfracture network finally filled with a second generation of dull luminescing q2 quartz mapping of brine and vapor inclusion assemblages in these successive quartz generations in combination with la icpms microanalysis shows that the fluids trapped before and after cu fe sulfide precipitation are very similar with respect to their major and minor element composition except for copper copper concentrations in inclusions associated with ore formation drop by two orders of magnitude in a tight pressure temperature interval between 21 and 14 mpa and 425 350 c several hundred degrees below the temperature of fluid exsolution from the magma copper deposition occurs within a limited p t region in which sulfide solubility shows strong normal temperature dependence while quartz solubility is retrograde this permits copper sulfide deposition while secondary vein permeability is generated by quartz dissolution the brittle to ductile transition of the quartz feldspar rich host rocks occurs in the same temperature range which further enhances vein reactivation and promotes cooling and expansion of fluids ascending across the transition from lithostatic to hydrostatic conditions

new insights into the hydrothermal evolution of skarn deposits a case study of the dongzhongla pb zn deposit in tibet sw china abstract revealing hydrothermal evolution from the early quartz sulfide to the late fluorite carbonate sulfide stages of skarn sulfide deposits is significant for understanding their ore formation processes but the detailed studies are rare in this study we choose the dongzhongla skarn pb zn deposit 0 38 mt pb zn located in central lhasa tibet as a case study and present detailed ore deposit geology and dataset of in situ chemical compositions of quartz in situ pb isotopic ratios of galena sulfur isotopic compositions of sulfides and c o isotopic compositions of hydrothermal calcite and wall rocks to address this issue there are two types of hydrothermal quartz in the early stage 1 the early phase euhedral quartz qz1 crosscut by quartz sulfide veins and 2 the late phase subhedral quartz qz2 coexisting with sulfides titaniq thermometer of qz1 and qz2 limits the two phases with a temperature range of 336 427 c mean 373 c and 357 461 c mean 386 c respectively the decreasing al concentrations of qz1 from core to rim suggest that magmatic fluids mixed with acidic meteoric water prevented the precipitation of sulfides during the early phase the increasing al and decreasing sulfur concentrations of qz2 indicate that the increasing ph values of hydrothermal fluids made principal sulfides precipitate during the late phase in addition fluid inclusions and c o isotopic studies reveal that the late stage minerals were deposited from low salinity

fluid and metal sources of the wenquan porphyry molybdenum deposit western qinling nw china the wenquan porphyry moybdenium deposit western qinling nw china with a resource of 247 million tonnes at 0 048 mo formed during triassic collision between south china and north china blocks ore fluids at wenquan vary widely in composition from single phase low salinity aqueous to low salinity vapor and hypersaline inclusions fluid inclusion assemblages in a quartz molybdenite vein contain 60 vol vapor are equant to negative crystal shaped and form clusters or distinct inclusion trails they yield homogenization temperatures of 285 295 c with an estimated trapping temperature of 425 c suggesting a paleodepth of about 5 km calculated at a pressure correction of 100 150 mpa hydrothermal k feldspar from early stockwork veins related to potassic alteration have calculated 18ofluid values of 1 9 to 1 9 hydrothermal sericite from an overprinting phyllic alteration associated with late quartz pyrite veins has calculated dfluid values between 68 and 60 and 18ofluid values from 3 7 to 1 4 these isotopic data suggest that both early and late stage fluids are dominated by magmatic fluids with influx of meteoric water during the late stage exsolution of volatiles from magma in a late stage open system results in more variable d values than an earlier closed system molybdenite and pyrite have 34s values ranging from 1 1 to 6 6 indicating that sulfur at wenquan had a magmatic source a linear relationship between 34s values of sulfides separated from early potassic alteration and late phyllic alteration could reflect incorporation of isotopically heavy evaporate sulfate into source magmas from underlying devonian sedimentary rocks during late alteration the 56fe whole rock values of altered porphyries range from 0 08 to 0 26 similar to 56fe values of 0 15 0 32 for pyrite from quartz veins related to both the potassic and phyllic alteration assemblages the 56fe values of pyrite are positively correlated to but in general slightly lighter than those of altered porphyries indicating similar metal sources moreover both altered porphyries and the pyrite are progressively enriched in heavy fe isotopes from biotite through potassic to late phyllic alteration consistent with isotopic evolution from an early lithostatic load to a late hydrostatic load the triassic intrusive rocks and fluids responsible for mineralization were derived from a deeply sourced hybrid mantle crustal magma crystallizing at a paleodepth of 5 km under lithostatic load external late triassic meteoric or devonian formational fluids became a part of the hydrothermal system during the post fracturing final stage of ore formation under a hydrostatic regime the formation of the wenquan magmatic hydrothermal systems spans the ductile brittle transition based on a normal thermal gradient as constrained by the temperature range of 550 300 c the early high temperature potassic alteration developed under a ductile regime whereas the later low temperature phyllic alteration correlates to a brittle environment where hydraulic rock fracturing enhances permeability and fluid circulation most sulfur and metals were precipitated from vapor rich fluids resulting from cooling and expansion of a single phase fluid exsolved from a hybrid magma

geochemistry of the waste isolation pilot plant wipp site southestern new mexico u s a abstract an extensive geochemical data base including analyses of major and minor solutes mineralogical studies of core samples and isotopic studies of waters carbonates and sulfates has been assembled for evaporites and related rocks in the northern delaware basin of southeastern new mexico these data were compiled for the geological and hydrological characterization of the waste isolation pilot plant wipp which is excavated in the evaporites of the salado formation these data were evaluated in order 1 to determine the stability of the evaporite mineralogy over geological time 2 to compare the aqueous geochemistry with host rock mineralogy 3 to delineate the nature and timing of water rock interactions such as dissolution and recrystallization 4 to determine the geological and climatic conditions that have governed groundwater recharge the resulting synthesis of data and current hypotheses concerning the origin composition and history of waters in the evaporite rocks and related units of the delaware basin provides a tentative conceptual model for the behavior of the water rock system since the deposition of the evaporites in the permian essential components of this model include 1 widespread late triassic early jurassic evaporite recrystallization 2 accumulation of deep basin brines isolated from meteoric recharge 3 evaporite dissolution by meteoric waters flowing in carbonates and sulfates interbedded in the uppermost permian section and at the basin margin 4 lateral rather than vertical infiltration of pre holocene meteoric waters in the uppermost permian section and 5 climatic conditions presently less conducive to recharge than in the late pleistocene

occurrence and origin of carbon dioxide in the fushan depression beibuwan basin south china sea abstract natural gases produced from the fushan depression beibuwan basin south china sea are generally rich in carbon dioxide the 13 c values of methane in these gases are within the range of 41 18 to 47 00 this together with the linearity of the 13 c values of methane to butane in the natural gas plots indicates that the hydrocarbon gases are of organic origin the 13 c co 2 values of these gases are in the range of 5 1 to 7 5 suggesting an inorganic origin a dominant mantle source for the co 2 in these gases was determined on the basis of a simple binary mixing model using the 13 c co 2 values and 3 he 4 he ratios of associated helium in these gases the primary geological controls on the occurrence of co 2 rich gas accumulations in the fushan depression are discussed following a comparison with other sedimentary basins in the region

u pb and ar ar geochronology of the fujiawu porphyry cu mo deposit dexing district southeast china implications for magmatism hydrothermal alteration and mineralization abstract the fujiawu porphyry cu mo deposit is one of several porphyry cu mo deposits in the dexing district jiangxi province southeast china new zircon shrimp u pb data yield a weighted mean 206 pb 238 u age of 172 0 2 1 and 168 5 1 4 ma from weakly altered granodiorite porphyry and quartz diorite porphyry respectively two hydrothermal biotites from granodiorite porphyry give an ar ar step heating plateau age of 169 9 1 8 and 168 7 1 8 ma hydrothermal apatite exsolved from altered biotite yields an isotope dilution thermal ionization mass spectrometry isochron age of 164 4 0 9 ma the apatite age is similar to the ages obtained from hydrothermal rutile 165 0 1 1 and 164 8 1 6 ma and indicates that the magmatism and hydrothermal activity in the fujiawu deposit occurred in the middle jurassic hydrothermal fluid circulation related to multiple stages of magma emplacement resulted in cu mo mineralization in the fujiawu porphyry deposit the zircon shrimp u pb ages and the published molybdenite re os age 170 9 1 5 ma represent the timing of magma crystallization and mo mineralization whereas the rutile and apatite u pb ages reflect the timing of cu mineralization following quartz diorite emplacement the data suggest slow cooling after emplacement of the quartz diorite porphyry

evidence for resetting of fluid inclusion temperatures from quartz cements in oilfields abstract quartz is a major pore occluding cement in north sea oilfield reservoir sandstones fluid inclusions yield homogenization temperatures t h which have been thought to represent growth temperatures for the host quartz however early diagenetic inclusions from the detrital grain overgrowth boundary yield excessively high palaeotemperatures which do not match the growth temperatures calculated from the depth of cementation the temperatures of these inclusions increase with present day depth of burial and approach present day reservoir temperatures this suggests that the inclusions have begun to reset towards present day pressure temperature conditions the t h of the inclusions hence represent burial temperatures rather than growth temperatures for the quartz experimental studies indicate that the amount of resetting undergone by an inclusion varies depending on its size shape and fluid composition a relationship between inclusion t h and these variables has been observed in inclusions from deeply buried quartz cements in the north sea

rutile inclusions in quartz crystals record decreasing temperature and pressure during the exhumation of the su lu uhp metamorphic belt in donghai east china donghai county in the jiangsu province of east china is known for its large scale production of high quality quartz crystals the quartz crystals are hosted within the su lu ultrahigh pressure uhp metamorphic belt they form in quartz veins hosted by eclogite and gneiss or along contacts between eclogite and gneiss and are mined as placer deposits in the quaternary sediments backscattered electron imaging of the rutile in rutile bearing euhedral quartz crystals from this region reveal three compositionally and texturally distinct generations of rutile encapsulated within the host quartz crystal the earliest generation of rutile r1 is brightest in bse reflecting enrichment in fe2o3 0 75 2 08 wt nb2o5 0 37 0 93 wt wo3 0 48 2 99 wt and zro2 0 005 0 105 wt relative to r2 and r3 r2 rutile overgrows r1 rutile and contains 0 66 1 11 wt fe2o3 0 45 0 74 wt nb2o5 0 09 0 20 wt wo3 and 0 001 0 013 wt zro2 r3 rutile which is the only rutile generation in contact with the host quartz crystals is darkest in bse and always overgrows r1 and rounded aggregates of r2 r3 rutile contains 0 40 0 68 wt fe2o3 0 13 0 37 wt nb2o5 0 03 0 12 wt wo3 and 0 001 wt zro2 oxygen isotopes decrease progressively from 0 6 to 1 5 in r1 rutile to 0 1 in r2 rutile to 5 1 to 0 3 in r3 rutile consistent with decreasing temperature of rutile crystallization combined application of the zr in rutile and ti in quartz thermobarometers indicate that these rutile generations precipitated at progressively lower pressures and temperatures consistent with previously determined retrograde metamorphic conditions of the su lu uhp belt r1 grew after peak metamorphism during retrograde eclogite facies metamorphism at temperatures between 720 and 800 c and pressures between 21 7 and 26 6 kbar during subsequent retrograde metamorphism r1 was fractured and partially brecciated and overgrown by r2 during epidote amphibolite facies retrograde metamorphism in the range of 400 to 500 c and 5 kbar zirconium concentrations of 14 ppm in r3 rutile and ti concentrations of 1 ppm in the co precipitated host quartz suggest that they both grew at low temperatures of 300 and pressures 2 kbars oscillatory growth zones in quartz revealed by cathodoluminescence suggest that no subsequent metamorphism or hydrothermal activity occurred after the formation of the host euhedral quartz crystals and is consistent with a low temperature of quartz crystallization the random distribution of rutile crystals in the quartz and the lack of evidence for rutile transport by hydrothermal fluids indicate that the host quartz formed by a dissolution replacement process whereby the original host mineral likely omphacite or garnet was replaced by quartz but the rutile was not significantly replaced or dissolved due to the low solubility of ti in low temperature hydrothermal fluids

applications of remote sensing for geohazard mapping in coastal and riverine environments this paper reviews various types of remote sensing that can be applied to mapping and monitoring riverine and coastal geohazards it focuses on flooding ground instability erosion and sedimentation mainly drawing on examples from the uk both airborne and space borne systems are examined with assessments of the merits limitations and relative costs of each system remote sensing offers a wide range of useful techniques for mapping coastal and riverine features particularly where there are access problems associated with sites prone to flooding or slope instability

evolution of formation waters in the permian basin united states late permian evaporated seawater to neogene meteoric water understanding subsurface waters is important for hydrocarbon exploration and development waters from the permian basin were collected and analyzed for stable isotopes ionic concentrations and strontium isotopes to determine their origin three main geochemical groups of waters are present group 1 has high 18o and d values with high total dissolved solids tds 100 240 g l including high concentrations of na cl and br group 1 waters contain distinctly less sodium na than chlorine cl on a molar basis similar to modern seawater group 2 and 3 waters have low 18o and d values group 2 waters have relatively low tds 4 75 g l group 3 waters have high tds 170 225 g l na and cl in approximately equal molar amounts and low br concentrations group 1 waters are interpreted as forming from highly evaporated seawater during precipitation of uppermost permian salts because of their high density those waters displaced preexisting formation waters throughout the permian basin during the latest permian waters in groups 2 and 3 came mainly from precipitation in the mountains of southeast new mexico those mountains formed during neogene tectonic uplifts group 3 waters acquired their na and cl by dissolution of upper permian salt many group 2 and 3 waters acquired their ca2 and so42 by dissolution of permian anhydrite or gypsum some waters contain a mixture of these groups understanding the origin of subsurface waters helps predict subsurface salinity aquifer drive sulfate reduction chemical reactions during water injection and chemistry of diagenetic waters

cathodoluminescence and trace element zoning in quartz phenocrysts and xenocrysts quartz phenocrysts and xenocrysts are a common component of volcanic rocks but rarely contribute to our understanding of magmatic or eruptive processes due to an apparent internal chemical and structural homogeneity scanning electron microscopy cathodoluminescence imaging sem cl and secondary ion mass spectroscopy ion microprobe analysis sims are used here to demonstrate that quartz crystals in volcanic rocks show hitherto unrecognised internal structural and chemical zoning two contrasting crystal morphologies have been studied porphyritic euhedral bipyramidal quartz crystals in dacite from bonne nuit bay jersey uk show fine scale growth zoning in sem cl zones are narrow 1 40 m wide planar parallel to crystal faces and overgrow more broadly zoned rounded cores these crystals are interpreted to have formed at small degrees of undercooling by diffusion controlled growth quiescent magma conditions are indicated by the preservation of an al rich diffusive boundary layer which has not been removed by melt shearing during convection in contrast rounded and embayed porphyritic quartz grains in a quartz dacite from the esperanza mine e1 salvador northern chile show broad internal sem cl zones with irregular boundaries some of which are truncated by grain margins indicating dissolution crystal rounding may occur by dissolution or melting due to thermal or thermal chemical disequilibrium with surrounding melt and embayments by gas bubble enhanced convective dissolution are consistent with the development of incipient ocelli textures strings of amphibole inclusions adjacent to quartz rims several episodes of rounding can be recognised in some xenocrysts ion microprobe sims analysis of quartz from both samples shows that a1 contents are higher in areas of bright cl emission previous studies of cl in quartz have suggested that several factors control luminescence although a1 substitution for si in sio4 tetrahedra may be partly responsible for sem cl zoning recorded in volcanic quartz additional mechanisms including the effect of growth rate on defect density probably also play a major role

geochemistry and accumulation of carbon dioxide gases in china we propose the following identification indicators for co2 of different origins based on data obtained from analyzing the molecular composition of 1198 gas samples the co2 carbon isotope values of 390 samples and the helium isotope composition of 256 samples collected from wells of 16 oil and gas bearing basins and gas seepages in china and reviewing literature on organic and inorganic co2 throughout the world co2 is of organic origin if co2 content 13cco22 is of inorganic origin if dgr13cco2 8 pmil or co2 60 and co2 is of either organic or inorganic origin or a mixtur of organic and inorganic origins if 10 pmil 13cco213cco2 values of organic co2 mainly range from 10 to 22 pmil in tectonically stable oil and gas bearing basins where deep faults and magmatism are undeveloped organic co2 occurs almost exclusively in tectonically active oil and gas bearing basins where active faults and magmatism are present or in areas of modern volcanic activity the dgr13cco2 values of inorganic co2 range from 2 to 8 pmil and are distributed along faults the inorganic co2 with a dgr13cco2 value of 0 3 pmil is of metamorphic origin and that with dgr13cco2 values of 6 2 pmil is mantle derived and of magmatic origin in china the dgr13cco2 values of inorganic co2 gas pools range from 3 41 to 8 44 pmil and the helium ratio r ra is 1 which indicates that these gases are typically derived from the mantle

identification of fluid inclusions in relation to their host microstructural domains in quartz by cathodoluminescence abstract the geometry of fluid trapping in relation to microfracture healing or filling was investigated using massive quartz vein samples characterized by multistage deformation and fluid trapping the multidisciplinary approach used in this study includes 1 mapping of oriented thin sections of quartz using the cathodoluminescence cl mode of a scanning electron microscope sem sem cl images display areas of different intensities from dark to white which correspond to the intensity of the cl and are caused by trace elements present in the quartz microfracture healing by newly formed quartz crystallization may occur under physical chemical conditions different from those which characterized the early quartz matrix formation thus evidences of linear cathodoluminescent markers have been searched and identified by paralleling sem cl images and transmitted light microphotographs data show that cathodoluminescence makes clearly visible the healed crack networks which are only detected in part by transmitted light microscopy the technique is essential to establish the microcrack chronology and to estimate the width affected by healing along a fluid inclusion trail such data are useful for the estimation of the microfracture permeability changes throughout the history of fluid migration 2 systematic and statistical analysis of the microstructural markers in horizontal and oriented planes using an interactive videographic analyzer which gives the geometry of the paleofluid pathways orientation dip and width of the veinlets fluid inclusion trails and cathodoluminescent microdomains 3 microthermometric and raman analyses of fluid inclusions in selected fluid inclusions for the determination of the p v t x conditions of fluid migration in a specific microcrack network studied quartz samples come from au mineralized quartz veins from the french massif central and some quartz samples from the cassiar mountains in british columbia have been observed for comparison in all samples the quartz matrix exhibits intense microfracturing suggesting strong brittle deformation which postdates the main stage of quartz lens formation the quartz veins are characterized by multistage quartz crystallization healed microfractures clear quartz bands as well as quartz comb veinlets were studied as functions of the physicochemical conditions in relation to stages of deformation and ore deposition this study shows that systematic measurements of microstructural marker orientations together with detailed fluid inclusion and mineral petrography and microthermometry may lead to a precise determination of ore fluid pathways and chronology

trace elements in hydrothermal quartz relationships to cathodoluminescent textures and insights into vein formation high resolution electron microprobe maps show the distribution of ti al ca k and fe among quartz growth zones revealed by scanning electron microscope cathodoluminescence sem cl from 12 hydrothermal ore deposits formed between 100 and 750 c the maps clearly show the relationships between trace elements and cl intensity in quartz among all samples no single trace element consistently correlates with variations in cl intensity however in vein quartz from five porphyry cu mo au deposits cl intensity always correlates positively with ti concentrations suggesting that ti is a cl activator in quartz formed at 400 c ti concentrations in most rutile bearing vein quartz from porphyry copper deposits indicate reasonable formation temperatures of 750 c using the titaniq geothermometer titanium concentrations of 10 ppm in all veins that formed at temperatures 350 c suggest a broad correlation between ti concentrations and temperature of quartz precipitation in quartz from most deposits formed at 2000 ppm but in high temperature quartz al concentrations are consistently in the range of several hundred ppm aluminum concentrations in quartz reflect the al solubility in hydrothermal fluids which is strongly dependent on ph aluminum concentrations in quartz therefore reflect fluctuations in ph that may drive metal sulfide precipitation in hydrothermal systems

relationships between sem cathodoluminescence response and trace element composition of hydrothermal vein quartz laser ablation icp ms data of hydrothermal vein quartz with zonation in scanning electron microscope cathodoluminescence reveal two groups of trace elements one that co varies in concentration with luminosity and another that remains uniform throughout bright luminosity correlates with a high total abundance of trace elements in early quartz including al up to 410 g g ti up to 240 g g k up to 330 g g li up to 8 g g na up to 36 g g and fe up to 20 g g up to 20 times lower concentrations of these elements are associated with dark luminosity in late quartz concentrations of p 21 g g ga 0 3 g g ge 1 3 g g sn 1 5 g g cu 0 3 g g and ag 0 1 g g demonstrate no relationship with luminosity charge balance cannot be achieved for bright luminescent quartz unless the presence of up to 6 g g h not analyzed by la icpms or interstitial al3 is invoked interestingly the inferred 6 g g h remains constant for quartz containing more than 10 mol total trace elements and might represent the solubility of h in hydrothermal quartz at temperatures between 450 and 700 c la icpms results indicate that the fluid chemistry determines the quartz trace element pattern which may serve as a monitor for the chemical environment from which quartz crystallized ratios of na al and ti al are uniform whereas k al evolves toward lower values with decreasing luminosity combined evidence including quartz vein textures silica solubility data and estimates of the temperature of quartz growth suggest that early quartz crystallized fast but late quartz grew more slowly at 350 to 425 c it is speculated that the higher the quartz growth rate is the more trace elements are incorporated into quartz besides the temperature dependence known from the literature clearly growth rate temperature and fluid chemistry are important parameters affecting luminosity however their relative importance may vary from case to case

chemical osmosis reverse chemical osmosis and the origin of subsurface brines abstract calculations using recently tabulated values of density and osmotic coefficient for nacl h2o indicate that overpressuring is more than adequate to overcome chemical osmosis and drive reverse chemical osmosis in sedimentary sequences the best demonstrated overpressuring mechanism is the rapid deposition of fine grained sediments the dehydration of gypsum contributes to overpressuring for brief time intervals at shallow depths whereas water evolved during the protracted conversion of smectite to illite is probably a subordinate but continuing contributor to overpressuring at greater depth occurrences of overpressuring in sedimentary sections older than cretaceous indicate that post depositional mechanisms such as tectonic compression and aquathermal pressuring must also operate the latter may be of major importance in geothermal areas with adequate low permeability seals and a nontrivial contributor in areas of normal geothermal gradient because of shales that sharply decrease normal fluid flow the strongest arguments for the importance to present day brine compositions of membrane concentration of sea water solutes are 1 1 the correlation of d values of water molecules of pore fluid with those of local meteoric water 2 2 the need for major sources of mg2 and cl in apparently evaporite free basins even where dissolution of halite is a major contributor of solute reverse chemical osmosis still operates to leak relatively dilute water of the associated diagenetic chemical reactions that of mg2 with limestone to form dolomite is particularly effective in generating concentrated cl brines rich in ca2 it decreases the concentration of mg2 increases that of ca2 and decreases those of both so42 and co32 by precipitating caco3 and caso4 because of the ca2 common ion effect

the noble gas geochemistry of natural co2 gas reservoirs from the colorado plateau and rocky mountain provinces usa identification of the source of co2 in natural reservoirs and development of physical models to account for the migration and interaction of this co2 with the groundwater is essential for developing a quantitative understanding of the long term storage potential of co2 in the subsurface we present the results of 57 noble gas determinations in co2 rich fields 82 from three natural reservoirs to the east of the colorado plateau uplift province usa bravo dome nm sheep mountain co and mccallum dome co and from two reservoirs from within the uplift area st john s dome az and mcelmo dome co we demonstrate that all fields have co2 3he ratios consistent with a dominantly magmatic source the most recent volcanics in the province date from 8 to 10 ka and are associated with the bravo dome field the oldest magmatic activity dates from 42 to 70 ma and is associated with the mcelmo dome field located in the tectonically stable centre of the colorado plateau co2 can be stored within the subsurface on a millennia timescale the manner and extent of contact of the co2 phase with the groundwater system is a critical parameter in using these systems as natural analogues for geological storage of anthropogenic co2 we show that coherent fractionation of groundwater 20ne 36ar with crustal radiogenic noble gases 4he 21ne 40ar is explained by a two stage re dissolution model stage 1 magmatic co2 injection into the groundwater system strips dissolved air derived noble gases asw and accumulated crustal radiogenic noble gas by co2 water phase partitioning the co2 containing the groundwater stripped gases provides the first reservoir fluid charge subsequent charges of co2 provide no more asw or crustal noble gases and serve only to dilute the original asw and crustal noble gas rich co2 reservoir scale preservation of concentration gradients in asw derived noble gases thus provide co2 filling direction this is seen in the bravo dome and st john s dome fields stage 2 the noble gases re dissolve into any available gas stripped groundwater this is modeled as a rayleigh distillation process and enables us to quantify for each sample 1 the volume of groundwater originally stripped on reservoir filling and 2 the volume of groundwater involved in subsequent interaction the original water volume that is gas stripped varies from as low as 0 0005 cm3 groundwater cm3 gas stp in one bravo dome sample to 2 56 cm3 groundwater cm3 gas stp in a st john s dome sample subsequent gas groundwater equilibration varies within all fields each showing a similar range from zero to 100 cm3 water cm3 gas at reservoir pressure and temperature

illumination of vein quartz textures in a porphyry copper ore deposit using scanned cathodoluminescence grasberg igneous complex irian jaya indonesia vein quartz from the grasberg igneous complex in irian jaya indonesia displays a wide range of features when observed using scanned cathodoluminescence imaging on the electron microscope examination of seventeen samples revealed concentric growth zoning quartz filled microfractures dark luminescence near sulfides changes in crystal size and orientation from vein edges to vein centers turbid growth zoning and the truncation of concentric growth zoning individual features observed along two large photomosaic traverses from vein margins to vein centers coupled with trace element analyses from the electron microprobe allow determination of a detailed history of fracture infilling the two traverses indicate a simple two stage history of crystal growth into an open fracture followed by mechanical closing of the fracture with resulting microfractures electron microprobe trace element analyses show that the fe content of quartz reaches values of up to 4900 ppm in dark luminescent regions near sulfide crystals and decreases smoothly to 200 ppm along traverses away from the sulfides the solution to the diffusion equation coupled with existing experimental data about fe diffusion in sio2 indicate the duration of the diffusion was perhaps on the order of thousands of years