changes in optical properties chemistry and micropore and mesopore characteristics of bituminous coal at the contact with dikes in the illinois basin abstract changes in high volatile bituminous coal pennsylvanian near contacts with two volcanic intrusions in illinois were investigated with respect to optical properties coal chemistry and coal pore structure vitrinite reflectance ro increases from 0 62 to 5 03 within a distance of 5 5 m from the larger dike and from 0 63 to 3 71 within 3 3 m from the small dike elemental chemistry of the coal shows distinct reductions in hydrogen and nitrogen content close to the intrusions no trend was observed for total sulfur content but decreases in sulfate content towards the dikes indicate thermochemical sulfate reduction tsr contact metamorphism has a dramatic effect on coal porosity and microporosity in particular around the large dike the micropore volume after a slight initial increase progressively decreases from 0 0417 cm3 g in coal situated 4 7 m from the intrusive contact to 0 0126 cm3 g at the contact strongly decreasing mesopore and micropore volumes in the altered zone together with frequent cleat and fracture filling by calcite indicate deteriorating conditions for both coalbed gas sorption and gas transmissibility

formation of si al mg ca rich zoned magnetite in an end permian phreatomagmatic pipe in the tunguska basin east siberia magma sediment interactions in the evaporite rich tunguska basin resulted in the formation of numerous phreatomagmatic pipes during emplacement of the siberian traps the pipes contain magnetite apatite deposits with copper and celestine mineralization we have performed a detailed petrographic and geochemical study of magnetite from long cores drilled through three pipe breccia structures near bratsk east siberia the magnetite samples are zoned and rich in si 5 3 wt sio2 ca al and mg they exhibit four textural types 1 massive ore in veins 2 coating on breccia clasts 3 replacement ore and 4 reworked ore at the crater base the textural types have different chemical characteristics breccia coating magnetite has relatively low mg content relative to si as compared to the other groups and appears to have formed at lower oxygen fugacity time series analyses of mgo variations in microprobe transects across si bearing magnetite in massive ore indicate that oscillatory zoning in the massive ore was controlled by an internal self organized process we suggest that hydrothermal fe rich brines were supplied from basalt sediment interaction zones in the evaporite rich sedimentary basin leading to magnetite ore deposition in the pipes hydrothermal fluid composition appears to be controlled by proximity to dolerite fragments temperature and oxygen fugacity magnetite from the pipes has attributes of iron oxide apatite deposits e g textures oscillatory zoning association with apatite and high si content but has higher mg and ca content and different mineral assemblages these features are similar to magnetite found in skarn deposits we conclude that the siberian traps related pipe magnetite deposit gives insight into the metamorphic and hydrothermal effects following magma emplacement in a sedimentary basin

paleoaquifer and deep burial related cements defined by regional cathodoluminescent patterns middle ordovician carbonates virginia middle ordovician ramp carbonates virginia were deposited in a subsiding foreland basin bordered on the southeast by tectonic highlands ramp carbonates were lithified in part by turbid marine cements but major cementation was by nonferroan clear rim and equant cements zoned defined by cathodoluminescence clear cements consist of nonluminescent oldest bright and dull youngest cements the zonation relates to increasingly reducing conditions of pore waters zoned cements in peritidal beds best developed in southeastern belts have complex zonations pendant to pore rimming fabrics and are associated with crystal silt which abuts all cement zones solutional cavities and erosional surfaces which locally truncate dull cement these cements are meteori vadose to shallow phreatic cements in northwestern exposures of peritidal beds are dominated by non zoned dull cement which lacks abundant evidence of early near surface precipitation major cementation of subtidal facies occurred under burial conditions burial cements best developed in southeastern belts have a simple zonation reflecting progressive burial up to 7 5 km 4 5 mi of the carbonate ramp shallow burial nonluminescent cement formed from oxidizing meteoric waters which expelled anoxic connate marine waters these meteoric waters were carried by aquifers from tectonic upland recharge areas on the southeastern basin margin bright cement formed under more reducing conditions following stagnation of the paleoaquifer with burial and possibly was precipitated at depths of 2 to 3 km 1 to 2 mi burial cements in northwestern exposures of subtidal beds are dominated by dull cement initial generations of which precipitated from downdip portions of aquif rs deeper burial dull calcite and ferroan dolomite cements largely formed at burial depths of 2 to 3 km 1 to 2 mi and temperatures of 75 to 135 c 165 to 275 f or more associated with hydrocarbon formation emplacement during the late devonian to mississippian latest clear dull cement fills tectonic fractures and was emplaced during late paleozoic alleghenian deformation probably at temperatures of 200 to 300 c 390 to 575 f and depths of 5 to 7 km 3 to 4 5 mi deeper burial diagenesis appears to be genetically linked to late paleozoic mississippi valley type mineralization in the southern appalachians zoned peritidal and burial cements are confined mainly to southeastern portions of the ramp where cementation was influenced by meteoric waters shed from tectonic uplands on the southeast and carried northwest by paleoaquifers northwestern portions of the ramp were influenced very little by upland sourced meteoric waters and nonzoned dull cements precipitated from relatively reducing waters the distribution of nonluminescent cement in middle ordovician subtidal facies defines the regional distribution of oxidizing portions of the paleoaquifer system such incursion of upland sourced oxidizing meteoric waters into ramp carbonates should be a common feature of foreland basin carbonates deposited adjacent to tectonic uplands furthermore foreland basin carbonates that undergo progressive burial should show a simple nonluminescent to bright to dull sequence of cement zones the close association of zoned cements and regional uplands in the middle ordovician sequence indicates the importance of assessing regional geologic relationships environmental parameters geologic history and tectonics in understanding regional cementation patterns and cementation processes of anci nt carbonate platforms

chemical diagenesis of carbonates in thin sections ion microprobe as a trace element tool abstract ion microprobe is a potential tool for determination of trace element concentrations directly in thin sections such an approach enables direct correlation of chemistry with microtextural features we demonstrate the utility of this instrument for sr mn fe and mg in calcites and dolomites at this stage the sensitivity is 10 ppm and the reproducibility is usually better than 15 relative percent the analyzed spots are 20 we believe that with more homogeneous standards at low concentrtion levels the technique is potentially capable of sensitivity in the ppb ppm ranges fe may prove an exeption from this prediction the technique may also prove suitable for determination of na ion microprobe can serve as a valuable tool for diagenetic and petrological studies of carbonates at this stage its major disadvantage is the poor optical resolution in transmitted light

geochemistry of trace elements in coals from the zhuji mine huainan coalfield anhui china the abundances of nine major elements and thirty eight trace elements in 520 samples of low sulfur coals from the zhuji mine huainan coalfield anhui china were determined samples were mainly collected from 10 minable coal seams of 29 boreholes during exploration the b content in coals shows that the influence of brackish water decreased toward the top of coal seams marine transgression and regression occurred frequently in the lower shihezi formation a wide range of elemental abundances is found weighted means of na k fe p be b co ni cr se sb ba and bi abundances in zhuji coals are higher and the remainder elements are either lower or equal to the average values of elements in coals of northern china compared to the chinese coals the zhuji coals are higher in na k be b cr co se sn sb and bi but lower in ti p li v and zn the zhuji coals are lower only in s p v and zn than average u s and world coals potassium mg ca mn sr as se sb and light rare earth elements lree had a tendency to be enriched in thicker coal seams whereas fe ti p v co ni y mo pb and heavy rare earth elements hree were inclined to concentrate in thinner coal seams the enrichment of some elements in the shanxi or upper shihezi formations is related to their depositional environments the elements are classified into three groups based on their stratigraphic distributions from coal seams 3 to 11 2 and the characteristics of each group are discussed lateral distributions of selected elements are also investigated the correlation coefficients of elemental abundances with ash content show that the elements may be classified into four groups related to modes of occurrence of these elements

high resolution scanning proton microprobe studies of micron scale trace element zoning in a secondary dolomite implications for studies of redox behaviour in dolomites abstract secondary rhomb shaped dolomites from the limestones of the gargano peninsula italy show fine well developed zones when viewed under cathodoluminescence in order to investigate the chemical origin of these zones this material was analyzed using the high resolution scanning proton microprobe the analyses show prominent concentric micrometre scale zones enriched in fe mn and zn at the ppm level the chemical zonations observed are however very much more complex than is shown by the cathodoluminescence image the cathodoluminescent zones correlate with variations in mn concentration but there is little negative quenching effect of fe which can be observed and there is no correlation among the zones of the different elements in contrast to the pronounced and sharp zoning of mn fe and zn observed sr is distributed homogeneously in the dolomite since the activities of fe ii mn ii and zn in solution are all controlled directly or indirectly by redox reactions whereas the behaviour of sr is uninfluenced by changes in oxidation potential these observations strongly suggest that the most important variable controlling the production of zones in these dolomites was eh we believe that the sharp zoning of mn fe and zn and the clear separation of one element from another indicate repeated influxes of pore water of differing eh and possibly ph carrying different amounts of fe ii mn ii and zn in solution

applications of the high resolution scanning proton microprobe in the earth sciences an overview abstract the proton microprobe uses a focused beam of high energy protons to generate x rays in a sample that is to be analyzed the major advantage of the proton microprobe as compared with the electron microprobe lies in its much lower x ray background this makes possible analyses at the 5 10 ppm concentration level with a resolution of 1 m the principles of operation of the proton microprobe are reviewed and the instrument compared with the ion probe and synchrotron x ray microprobe examples of its use in analyzing finely zoned dolomite and in investigating the late stage concentration of elements on grain boundaries in garnet lherzolite xenoliths are reviewed the proton and x ray microprobes are likely to contribute increasing amounts of high quality trace element data in the near future

in situ characterization of dolomite crystals evaluation of dolomitization process and its effect on zoning dolomitization is a dissolution re precipitation process which proceeds via micrometre scale interface reaction horizons however the effect of this fundamental local medium of replacement process on precipitated dolomite crystals is rarely investigated for this purpose dolomite samples of ordovician boat harbour formation carbonates newfoundland canada from main brook and daniel s harbour about 150 km apart were studied the investigation used high resolution approaches to carry out imaging and elemental analyses of individual dolomite crystals including scanning electron microscopy scanning electron microscopy based cathodoluminescence secondary ion mass spectrometry and electron microprobe analysis the purpose was to better understand geochemical variations across the crystal traverses and their association with dolomite replacement processes and conditions the scanning electron microscopy based cathodoluminescence zoning character reveals three major crystal facies distinctly planar boundaries zoned core and indistinctly zoned core are zoned dolomite crystal facies in burial dolomite from main brook relatively unzoned crystal facies was identified in that of daniel s harbour compositionally zoned dolomite crystals are characterized by decreasing sr na y and ree but increasing mn and fe from core to rim sections core to rim zoning was not found for major mg and ca elements the zoning exhibited by the replacive dolomite crystals is interpreted to be principally a result of limited exchange between solutes of the bulk pore fluid and those of dissolving precursor marine carbonate in tandem with petrographic features the systematic compositional zoning character demonstrates that the effectiveness of the dolomitization process grades from indistinctly zoned core to relatively unzoned crystal facies via interface reaction horizons homogenization of major elements of core and rim sections seen in distinctly zoned core crystal facies and to a much greater extent in relatively unzoned crystal facies via a secondary reaction interface is the first recognized stage of the maturation process followed by homogenization of the trace elements seen largely in relatively unzoned crystal facies

characterization of intrusive rocks and ree geochemistry of coals from the zhuji coal mine huainan coalfield anhui china abstract rare earth element ree concentrations in coals are a source of information relevant to the evolution of source rocks depositional environment and epigenetic tectonic activity as well as the effects of igneous intrusions in this study 186 coal samples 11 intrusion affected coal samples 4 samples representative of the intrusive rocks one coal roof and one parting samples were collected from 29 boreholes at the zhuji coal mine huainan coalfield anhui province china the main objective is to characterize the intrusive rocks in the coal bearing sequence and to investigate the correlation of ree parameters in the coals with the source rocks depositional environment localized faults igneous intrusions and thickness of the coal beds a sequence from base to top of acidic to basic intrusive rocks through the coal bearing strata was identified which possibly corresponds to different intrusive episodes of granite diorite monzonite and gabbro both the ree contents and degree of fractionation of light rare earth elements lree and heavy rare earth elements hree increase from acidic to basic rocks most rocks are slightly depleted in ce but highly depleted in eu the ree concentrations in coals from the zhuiji mine average of 118 g g are nearly identical to recently updated average chinese values but significantly higher than global values the ree content of the intrusion affected coals is not distinctively different from that of the other coals p 0 2 and ree concentrations of the igneous rocks appear to have no clear relationship to those of the intrusion affected coals the depositional environment and source rocks are presumably the main ree contributors to the coal accumulation basin the ree content in coals from fault affected boreholes is higher than that in other boreholes and this trend is stronger in the coal seams of the upper strata the hree tend to be incorporated into thinner coal seams and the degree of fractionation between lree and hree of the coal forming materials increases with coal thickness

biogeochemical controls on mercury stable isotope compositions of world coal deposits a review abstract coal deposits were important natural hg sinks in the late paleozoic and middle late mesozoic coal combustion since the industrial revolution has emitted more than 35 000 t of hg into the atmosphere environmental geochemistry research on hg in coal is essential to understand the natural hg cycle throughout earth history and the present day hg cycle under human perturbation in this review we summarize the methods of hg isotope measurement in coals and compile recently published hg isotope data of 200 world coal samples according to their locations formation periods carboniferous permian jurassic cretaceous early middle cenozoic and ranks anthracite bituminous coal subbituminous coal lignite and illustrate the controls of sources and biogeochemical processes on hg isotope compositions in coal deposits up to 4 7 variation 3 90 to 0 77 in mass dependent fractionation mdf represented by 202 hg and 1 0 variation 0 63 to 0 34 in mass independent fractionation mif represented by 199 hg are observed in world coal deposit with an average value of 1 16 0 79 1sd and 0 11 0 18 1sd for 202 hg and 199 hg respectively we find that coal 202 hg and 199 hg are broadly controlled by two source materials terrestrial plants biogenic hg and crustal rocks geogenic hg accounting for 37 46 and 54 63 of hg in coals no clear trends are seen in neither 202 hg vs coal forming periods nor 202 hg vs coal ranks which we attribute to important overlapping of 202 hg in the source materials of different coal forming periods and the multidirectional hg mdf during coalification interestingly a step wise increase in total hg and a disappearance of 199 hg are observed along with increasing coal rank suggesting the addition of hydrothermal hg into high rank coals the hydrothermal fluids not only upgraded the coal ranks but also increased the hg concentrations and 199 hg of coals in addition the addition of hydrothermal hg into coal deposits was also partly responsible for the comparatively higher total hg and 199 hg in the late paleozoic coals relative to the mesozoic and cenozoic coals the co variation of atmospheric oxygen levels and 199 hg of coals at different coal forming time widows suggests that the removal of biogenic hg in response to widespread swamp fires may have increased the 199 hg in late paleozoic coals as well our study indicates that coal hg isotopes provide new insights into the biogeochemical cycle of hg in coal deposits and that 199 hg is a robust indicator to trace hg addition removal in coal deposits and biogeochemical processes magmatic intrusion hydrothermal fluids penetration burning of coal swamp occurring during coal deposition

mercury and trace element contents of donbas coals and associated mine water in the vicinity of donetsk ukraine abstract mercury rich coals in the donets basin donbas region of ukraine were sampled in active underground mines to assess the levels of potentially harmful elements and the potential for dispersion of metals through use of this coal for 29 samples representing c 11 to m 3 carboniferous coals mercury contents range from 0 02 to 3 5 ppm whole coal dry basis mercury is well correlated with pyritic sulfur 0 01 to 3 2 wt with an r 2 of 0 614 one outlier excluded sulfides in these samples show enrichment of minor constituents in late stage pyrite formed as a result of interaction of coal with hydrothermal fluids mine water sampled at depth and at surface collection points does not show enrichment of trace metals at harmful levels indicating pyrite stability at subsurface conditions four samples of coal exposed in the defunct open cast nikitovka mercury mines in gorlovka have extreme mercury contents of 12 8 to 25 5 ppm this coal was formerly produced as a byproduct of extracting sandstone hosted cinnabar ore access to these workings is unrestricted and small amounts of extreme mercury rich coal are collected for domestic use posing a limited human health hazard more widespread hazards are posed by the abandoned nikitovka mercury processing plant the extensive mercury mine tailings and mercury enrichment of soils extending into residential areas of gorlovka

nakhlak carbonate hosted pb ag deposit isfahan province iran a geological mineralogical geochemical fluid inclusion and sulfur isotope study abstract the upper cretaceous nakhlak epigenetic vein type pb ag deposit is located 55 km northeast of the town of anarak in isfahan province iran the deposit contains 7 mt of galena barite ore with an average grade of 8 33 pb 0 38 zn and 72 ppm ag the ore mineralization occurs as stratabound epigenetic steeply dipping east west trending veins in faulted or fracture controlled upper cretaceous sadar carbonates galena and barite are the primary minerals minor sphalerite tennantite tetrahedrite pyrite and chalcopyrite occur as inclusions in galena cerussite with minor amounts of anglesite and plattnerite formed in the oxidized supergene zone the ore and ore related minerals were deposited in the hydrothermally dolomitized carbonate host rock containing saddle shaped dolomite geochemically the dolomitized carbonate host rocks are enriched in mgo fe 2 o 3 mno pb zn and ba but depleted in cao the galena concentrate contains high values of ag 932 ppm sb 342 ppm cu 422 ppm as 91 ppm and zn 296 ppm the presence of these trace elements indicates a low temperature type of galena mineralization this interpretation is corroborated by fluid inclusions containing 12 98 wt nacl equivalent salinity the inclusions homogenize at the low temperature of about 152 1 c the similarity between 34 s v cdt values in nakhlak barite and permian triassic 34 s marine sulfate values indicates that the nakhlak sulfur was probably provided from evaporates of permian triassic age the 34 s v cdt values of galena and barite samples occupy the ranges of 1 04 to 8 62 and 10 95 to 13 71 respectively and are similar to mississippi valley type mvt deposits the low temperature basinal fluids evaporate originated sulfur and fault or fracture controlled galena rich veins in the nakhlak deposit resemble the type of geological features documented in pb rich mvt deposits

mercury stable isotope compositions in magmatic affected coal deposits new insights to mercury sources migration and enrichment abstract mercury hg is commonly present at trace levels in coal deposits geological processes particularly magmatic intrusion and hydrothermal cycling in coal bearing strata can significantly increase hg levels in coals however the effects of thermal stress magmatic components magmatic hydrothermal fluids low temperature hydrothermal fluids on hg enrichment are confounded in a magmatic affected coal basin here we demonstrate the use of stable hg isotopes to understand the controlling factors on hg enrichment in two well known chinese coal deposits affected by magmatic activities wulantuga low temperature hydrothermal altered coal deposit and wolonghu magmatic intruded coal deposit the wulantuga no 6 coal seam is extremely enriched in hg varying from 0 37 g g in middle coal benches to 40 90 g g in the upper most and lowest coal benches approximately 2 5 variation in mass dependent fractionation mdf 3 07 to 0 58 in 202hg is observed 202hg vs 1 hg diagram suggests a mixture of three hg end members original hydrothermal fluids fractionated hydrothermal fluids and native coal forming materials in addition wulantuga coals all show positive mass independent fractionation mif of odd isotopes up to 0 87 in 199hg and 0 66 in 201hg the 199hg 201hg ratios range from 1 3 to 3 3 suggesting that a large fraction of photodegraded methylmercury was likely incorporated into the coal deposit the magmatic intruded wolonghu no 8 coal seam is only slightly to intermediately enriched in hg varying from 0 10 g g to 0 40 g g the coals near the contact sill 5 cm 1 81 to 1 52 have similar 202hg as the magmatic sill rocks 2 05 to 1 80 both with insignificant mif values coals far from the contact sill 15 cm have 202hg values varying from 3 40 to 1 61 and 199hg varying from 0 26 to 0 58 which are significantly enriched in light and odd hg isotopes compared to coals near the contact sill 199hg and 201hg in wolonghu coals far from the contact sill resemble those of meteoritic waters and seawater in both magnitude and 199hg 201hg ratio our two case studies show significant mdf and mif of hg isotopes which inform on hg migration and sequestration in the magmatic rocks and coal deposits and on the roles of meteoric water and hydrothermal fluid circulation

diagenesis of carbonate cements in permo triassic sandstones from the iberian range spain evidence from chemical composition and stable isotopes petrographic chemical and stable isotope investigations have been made on calcite dolomite and fe dolomite ankerite from permian triassic clastic sequences from the iberian range spain calcite and dolomite cements have precipitated before the fe dolomite ankerite calcite however has also formed by calcitization of dolomite due to uplift the negative 13cpdb values 9 51 to 2 13 in these carbonates suggest derivation of carbon from oxidation of organic matter in the early carbonates and from decarboxylation of organic matter in the late fe dolomite ankerite early diagenetic dolomitic cements have heavier 13c 3 54 higher mn mn fe and mn mn mg and lower fe fe mg ratios than later diagenetic dolomitic cements the latters are also characterized by lighter 18opdb 10 64 than the early cements due to increase in temperature and to pore water mineral reactions

chemical controls of cathodoluminescence of natural dolomites and calcites new data and review calcites and dolomites from the late precambrian bonahaven formation of scotland exhibit luminescence when mnco3 0 03 wt dolomite or 0 06 wt calcite and feco3 2 2 5 wt dolomite comparison with other published data shows close similarity in the position of fe quenching in dolomite but more variability in the position of mn activation in calcites and dolomites and the onset of fe quenching in calcites these anomalies are thought to relate to chemical controls subsidiary to the dominant factors of fe and mn concentration it is not practical to make a useful comparison between operating conditions of different luminescence instruments because of differences in design and an inability to measure routinely the current actually on the specimen surface

ion microprobe analysis of trace elements in calcite with an application to the cathodoluminescence zonation of limestone cements from the lower carboniferous of south wales u k ion microprobe analysis offers high spatial resolution 10 m and low detection limits for many elements in calcite detection limits are likely to be instrument dependent the values given here are specific to the instrument used a modified aei im 20 and more recent instrument designs should give lower detection limits li na and k signals have been observed and detection limits are estimated to be 10 ppm the detection limit for pb is in the range 10 50 ppm zn and ba suffer from significant molecular interferences which impose higher detection limits mg fe mn and sr were standardised against three chemically analysed calcites detection limits in the range 1 5 ppm were obtained for mg mn and sr but fe is subject to interference by a hydride species so that the detection limit is determined by vacuum conditions calcite cements in sections cut from a lower carboniferous limestone from south wales can be divided texturally into four zones analyses were made for mg fe mn and sr only sr differs among the zones mn is the main activator of cathodoluminescence cl in these cements when the fe content is up to 1600 ppm there is a positive relationship between cl intensity and mn content fe acts as a suppressor of cl intensity for a given mn concentration the cl intensity decreases as the fe content increases for fe contents 1600 ppm the cl intensity may be negatively related to the mn concentration when the mn content is below 125 150 ppm the fe content has little discernible effect on the cl intensity in these cements non luminescence can only be predicted with confidence if the mn concentration is below 25 ppm there is no critical concentration of fe up to 7000 ppm or critical fe mn ratio in the range 0 26 which always causes mn bearing locations to become extinct with respect to cl the present data are compared with those from the literature and a diagram is constructed which represents the region of fe mn composition space where luminescence can occur conflicting evidence regarding the relative importance of fe mn ratio and absolute fe and mn concentrations can be reconciled both concentrations and fe mn ratio are involved in controlling luminescence

the control of cathodoluminescence in dolomite by iron and manganese variations in the cathodoluminescent properties of carbonates are usually attributed to differing proportions of manganese mn2 as the most important activator and iron fe2 as the main inhibitor of luminescence interactions between manganese and iron concentrations and the luminescent properties of dolomite are demonstrated by petrographic and chemical analyses of 86 samples of dolomite representing a range of depositional environments and ages cambrian to cretaceous and a wide geographical distribution north america and europe iron and manganese are positively correlated in the dolomites with the former showing a greater range of variation very small amounts of manganese are sufficient to activate the luminescence and as little as 100 ppm mn2 is present in highly luminescing samples the intensity of luminescence is not proportional to the manganese concentration iron begins to quench luminescence as its concentration reaches 10 000 ppm above that level luminescence is rapidly lost and total extinction occurs among samples containing more than 15 000 ppm fe2 regardless of the manganese concentration

trace element and isotopic zonation in vein calcite from the mendip hills uk with spatial process correlation analysis abstract high resolution scanning proton microprobe spm analyses of fissure filling calcite from the mendip hills uk show fine scale chemical zonation patterns in fe and mn concentrations from fissure centre to wall these fluctuations are sharp and steep peaks of 0 01 0 1 mm width with concentrations changing by as much as 8000 ppm zonation in pb and zn is similar to that obtained for mn and fe and maxima in the concentrations of these two elements are correlated with maxima in mn concentration longer wavelength fluctuations 1 0 3 0 mm are evident in data obtained for sr for which changes in concentration are gradual and fluctuate by at most 500 ppm auto correlation calculations show that oscillations in the mn and fe data have a wavelength of 0 9 1 3 mm in contrast to auto correlations and cross correlations with zn and pb which indicate wavelengths of 0 4 mm strontium correlations indicate a peak to trough distance of 4 2 mm which implies a much longer wavelength fluctuation in the sr data cross correlations also clearly show that pb and zn concentrations co vary strongly cross correlation function value of 0 7 at lag 0 but all other cross correlations are weak these computations demonstrate that intrinsic controls on trace element partitioning cannot alone account for the observed patterns long period fluctuations are interpreted to result from a sustained change in the starting composition of the aqueous phase while the high frequency oscillations are interpreted to be caused by mixing reactions among fluids that have reacted with different portions of country rock prior to calcite precipitation analyses of the carbon oxygen and strontium isotopes from these vein calcites have also been completed 18o plotted as a function of 13c results in an inverted triangular array we interpret this along with the trace element data as resulting from three distinct fluids participating in the formation of these fissure fills a low mn fe high sr marine fluid apex at 18o 0 13c 4 both relative to pdb a high mn fe low sr hydrothermal fluid 2 9 5 and a low mn fe low sr meteoric fluid 12 5 the trace element and isotopic compositions of this zoned calcite thus document the following processes in detail 1 the formation of a meteoric fissure system triassic 2 reactions with hotter and more reduced circulating fluids and 3 the subsequent flooding of the system with seawater during transgression of the area rhaetian early jurassic strontium isotopic data from a belemnite located within one of the fissures gives an early jurassic age of approximately 198 ma hot reduced fluids with high metal concentrations were probably forced up into these fissures by seismic pumping during movement on associated regional faults

mercury distribution in coals influenced by magmatic intrusions and surface waters from the huaibei coal mining district anhui china the hg concentrations in 108 samples comprising 81 coal samples 1 igneous rock 2 parting rock samples and 24 water samples from the huaibei coal mining district china were determined by cold vapor atomic fluorescence spectrometry the abundance and distribution of hg in different coal mines and coal seams were studied the weighted average hg concentration for all coal samples in the huaibei coalfield is 0 42 mg kg which is about twice that of average chinese coals from southwestern to northeastern coalfield hg concentration shows a decreasing trend which is presumably related to magmatic activity and fault structures the relatively high hg levels are observed in coal seams nos 6 7 and 10 in the southwestern coal mines correlation analysis indicates that hg in the southwestern and southernmost coals with high hg concentrations is associated with pyrite the hg concentrations in surface waters in the huaibei coal mining district range from 10 to 60 ng l and display a decreasing trend with distance from a coal waste pile but are lower than the regulated levels for hg in drinking water

geochemistry of trace elements in chinese coals a review of abundances genetic types impacts on human health and industrial utilization abstract china will continue to be one of the largest coal producers and users in the world the high volume of coal use in china has focused attention on the amounts of toxic trace elements released from coal combustions and also the valuable trace elements extracted or potentially utilized from coal ash compared to world coals chinese coals have normal background values for most trace elements with the exception of higher li 31 8 g g zr 89 5 g g nb 9 44 g g ta 0 62 g g hf 3 71 g g th 5 84 g g and rare earth elements la lu y 136 g g this is not only due to the higher ash yields of chinese coals but also to alkali volcanic ashes found in some southwestern coals the background values of toxic elements of hg 0 163 g g as 3 79 g g and f 130 g g in chinese coals are comparable to coals from most other countries the genetic types for trace element enrichment of chinese coals include source rock controlled marine environment controlled hydrothermal fluid controlled including magmatic low temperature hydrothermal fluid and submarine exhalation controlled subtypes groundwater controlled and volcanic ash controlled the background values of trace elements were dominated by sediment source regions low temperature hydrothermal fluid was one of the major factors for the local enrichment of trace elements in southwestern china serious human health problems caused by indoor combustion of coal in china include endemic fluorosis arsenosis selenosis and lung cancer endemic fluorosis mainly occurring in western guizhou was mostly attributed to the high fluorine in clay that was used as a briquette binder for fine coals in addition to a small quantity of fluorine from coal fluorine in the coal from endemic fluorosis areas of western guizhou is within the usual range found in china and the world endemic arsenosis in southwestern guizhou is attributed to indoor combustion of high as coal endemic selenosis in enshi of hubei was due to high se in carbonaceous siliceous rocks and carbonaceous shales fine particles of quartz released into air during coal combustion are hypothesized as a possible cause for the lung cancer epidemic in xuanwei yunnan china valuable elements including ge ga u ree rare earth element nb zr and re are concentrated to levels comparable to conventional economic deposits in several coals or coal bearing strata in china the ge deposits at lincang yunnan province and wulantuga inner mongolia have been exploited and industrially utilized the enrichment of ge in the two deposits was caused by hydrothermal fluids associated with adjacent granitoids the ga al ore deposit in the jungar coalfield inner mongolia was derived from the neighboring weathered and oxidized bauxite of the benxi formation pennsylvanian the nb ta zr hf ree ga deposits in the late permian coal bearing strata of eastern yunnan and chongqing of southwestern china were attributed to ashes of the alkali volcanic eruptions

reworking of amino acid in marine sediments stable carbon isotopic composition of amino acids in sediments along the washington coast the stable carbon isotopic composition of nine individual amino acids were investigated in phytoplankton and zooplankton estuarine plankton terrigenous material marine fecal material and clay mineral isolates collected along the washington coast the clay fraction was isolated from suspended sediments of the columbia river the mineral source and three shelf and slope stations mineral deposition sites in the sediments terrigenous amino acids were replaced by those of marine origin and microbial reworking of the amino acids further influenced their d 13 c compositions based on changes in isotopic composition individual amino acids could be roughly divided into three groups 1 leucine and proline had isotopic shifts similar to bulk organic matter on average 80 of these river delivered amino acids were replaced by marine derived material 2 alanine isoleucine glutamic acid aspartic acid and phenylalanine had intermediate isotopic shifts these isotopic compositions are consistent with both the expected isotopic fractionation associated with microbial resynthesis of amino acids using marine substrates and or preservation of 50 of the terrigenous component in the marine environment 3 glycine and valine exhibited isotopic values outside the range of our sampled end members their unusual isotopic compositions are attributed to reworking of their isotopic signal during diagenesis microbial resynthesis of amino acids during growth on mixed substrates may account for nearly all the observed variation in amino acid isotopic composition similarity between the amino acid isotopic composition of the fecal material and that of the clay isolates suggests that alterations of the isotopic composition of the amino acids might occur while the amino acids are in distinct organicrich debris prior to long term association with the sediment

estimations of clarkes for carbonaceous biolithes world averages for trace element contents in black shales and coals abstract black shale and coal clarke values are the average trace element contents in the world black shales and coals these calculations are made in russian geochemistry but up to now are poorly known in the west modern tables of black shale and coal clarkes are presented based on comprehensive calculations using very large amount of information thousands analyses of black shales coals and coal ashes for trace elements in black shale geochemistry three figures were calculated for each main lithologies terrigenous tuff chert and carbonate two clarke estimations are presented named lithological k1 and lithostratigraphical k2 in coal geochemistry seven figures were calculated for each trace element average content in hard coals and their ashes average content in brown coals and their ashes average content in all coals and their ashes and coal affinity index or coalphile index average content in all ashes clarke values of sedimentary rocks the black shale and coal clarkes presented here provide an important scientific base for many geochemical comparisons and issues

the occurrence and origin of selenium minerals in se rich stone coals spoils and their adjacent soils in yutangba china abstract several se bearing minerals have been identified in se rich stone coal spoils and their adjacent organic rich soils in yutangba of enshi china where human se toxicity occurred in the 1960s these minerals mainly include native se se 0 krutaite cuse 2 klockmannite cuse mandarinoite fe 2 seo 3 3 6h 2 o se bearing chalcopyrite cufe se s 2 and pyrite fe se s 2 the assemblage of native se krutaite klockmannite and se bearing pyrite and chalcopyrite is primarily present in the stone coal near a fault plane while the assemblage of native se and krutaite is found in the se rich carbonaceous mudstone and organic rich soils which are 60 m away from the stone coal exposure the assemblage of mandarinoite and native se is present in abandoned stone coal spoils where natural combustion occurred native se is quite extensive in the stone coal spoils and nearby soils derived from them the co occurrence of cu se minerals and native se indicates that these minerals could have formed under a relatively acidic and reducing environment below 220 c and suggests that cu could play a significant role in fixing reduced se ions in the acidic organic rich surface environment furthermore the occurrence of mandarinoite suggests that iron oxides constrain the geochemical behavior of se in oxidizing environments our observations provide new insights into the mechanisms of se fixation and accumulation during weathering of se rich rocks

trace element zoning in dolomite proton microprobe data and thermodynamic constraints on fluid compositions abstract lower cretaceous euhedral dolomite crystals from the gargano peninsula italy have been analyzed by scanning proton microprobe spm for the trace elements sr zn fe mn cu ni y and rb intricate decoupled zoning patterns for fe mn and zn are a ubiquitous feature of the outer 55 microns of the dolomite crystals differences between peak and baseline concentrations are on the order of several hundred parts per million in contrast sr concentrations are nearly constant at 110 ppm the concentrations of the other cations are all low cu 20 ppm y 10 ppm and ni and rb 5 ppm in order to investigate the origin of the gargano dolomite we have used the method of tardy and garrels to estimate equilibrium partition coefficients for divalent cations between aqueous fluids and the dolomite structure 18o measurements on gargano dolomites show that they formed at a maximum temperature of 75 c 7 c estimated equilibrium constants for substitution of the cation m into dolomite calculated baseline molar cation ratios for fluids in equilibrium with gargano dolomite and measured cation ratios for seawater and marine sediment pore fluids at 75 c are as follows m n k eq log10 calculated ratio log10m n measured ratio in seawater log10m n measured ratio marine pore fluids mn mg 1 27 4 62 7 17 2 75 fe mg 12 66 4 77 6 57 3 81 zn mg 6 85 5 27 6 72 4 84 sr ca 0 17 2 94 1 92 1 83 cation ratios of fluids in equilibrium with the baseline concentrations of mn fe and zn in the gargano dolomite samples are bracketed by the cation ratios measured in seawater and in marine sediment pore fluids the factor often discrepancy for sr in the predicted fluid compared with seawater is probably due to nonideal mixing of sr on the ca site the decoupled fluctuations of the mn and fe concentrations in these samples can be explained by eh fluctuations in the reactant fluid zn fluctuations may be a product of ph dependent oxide surface reactions to test this hypothesis of origin unzoned tertiary dolomites from enewetak atoll and from the bahama bank have also been analyzed the homogeneous sr concentration in the gargano dolomite is similar to the sr concentrations measured in the enewetak atoll 175 ppm and bahama bank 150 ppm dolomites samples which in both cases almost certainly grew in equilibrium with seawater gargano baseline mn 20 ppm and fe 80 ppm concentrations are also much the same as the bahama bank dolomite mn 15 ppm and fe 140 ppm concentrations the lack of sr zoning in the gargano samples and the similarity of their sr mn and fe content to dolomite that formed in equilibrium with seawater indicates that the dolomitizing fluid was most likely seawater or a seawater type brine low sr concentrations 12 ppm in pore filling calcite from the gargano suggests that in contrast to the dolomite the calcite precipitated from meteoric fluids

modes of occurrence of mercury and other trace elements in coals from the warrior field black warrior basin northwestern alabama abstract the mineralogic residence and abundance of trace metals is an important environmental issue data from the usgs coal quality database show that potentially toxic elements including hg as mo se cu and tl are enriched in a subset of coal samples in the black warrior basin of alabama usa although the coal as mined typically is low in these elements localized enrichments occur in high pyrite coals and near faults microscopic analyses demonstrate that the residence of these elements is dominantly in a late stage pyrite associated with structurally disrupted coal further our data suggest addition of hg to the coal matrix as well the source of these trace elements was hydrothermal fluids driven into the black warrior basin by alleghanian age tectonism

cathodoluminescence in calcite cements new insights on pb and zn sensitizing mn activation and fe quenching at low trace element concentrations abstract the role of pb and zn as sensitizers of cathodolumines cl in sedimentary carbonates is still speculative as is the relationship between mn fe and cl intensity at low concentrations of mn and fe we address these questions using calcite cements from the lower oligocene suwannee formation of florida which have mean mn pb zn and fe concentrations less than 45 ppm only a small fraction of these cements exhibit visible cl but when present the luminescence is orange to reddish orange trace element contents were measured using a synchrotron x ray fluorescence microprobe and cl intensity was approximated by spot metered photomicrograph exposure times based on mn and fe contents four cement populations can be defined group i is luminescent calcite with mn 25 ppm and molar mn fe 1 8 group ii contains both luminescent and nonluminescent cements all with mn 25 ppm molar mn fe 25 ppm molar mn fe 100 ppm group iv is nonluminescent calcite with mn 25 ppm and variable fe these groupings and statistical analyses of the data mann whitney tests and factor analyses confirm that 25 ppm mn is necessary to initiate visible cl and that mn is the sole control on cl intensity when mn and fe contents are very low 100 ppm the data also establish 100 ppm fe as a new minimum for the quenching of cl when mn is below 200 ppm there is no evidence in our data that pb or zn concentrations in tens of parts per million either activate or sensitize cl the mann whitney test shows that there is no statistical evidence at the 95 confidence level to indicate that luminescent and nonluminescent cements reflect different populations of pb and zn except for group ii cements that have more pb in nonluminescent cements than in otherwise chemically equivalent luminescent cements factor analysis shows that cl intensity in all luminescent cements is unrelated to pb or zn concentrations given that pb or zn sensitizing is lacking in low mn calcites like the suwannee cements it is hard to imagine how these elements could play a significant role in calcites containing even more mn as is typical of most sedimentary carbonates

geological and geochemical characteristics of high arsenic coals from endemic arsenosis areas in southwestern guizhou province china southwest guizhou province is one of the most important areas of disseminated sediment hosted type au deposits in china and is an important area of coal production the chemistry of most of the coals in sw guizhou is similar to those in other parts of china their as content is near the chinese coal average but some local small coal mines contain high as coals the highest as content is up to 3 5 wt in the coal the use of high as coals has caused in excess of 3000 cases of as poisoning in several villages the high as coals are in the longtan formation which is an alternating marine facies and terrestrial facies the coals are distributed on both sides of faults that parallel the regional anticlinal axis the as content of coal is higher closer to the fault plane the as content of coal changes greatly in different coal beds and different locations of the same bed geological structures such as anticlines faults and sedimentary strata control the distribution of high as coals small au deposits as well as sb hg and th mineralization are found near the high as coals although some as bearing minerals such as pyrite arsenopyrite realgar as bearing sulfate as bearing clays and phosphate are found in the high as coals their contents cannot account for the abundance of as in some coals analysis of the coal indicates that as mainly exists in the form of as5 and as3 perhaps combined with organic compounds the occurrence of such exceptionally high as contents in coal and the fact that the as is dominantly organically associated are unique observations

direct determination of strontium enrichment on grain boundaries in a garnet lherzolite xenolith by proton microprobe analysis the mechanisms by which trace and radiogenic elements are held and transported in the earth s mantle are of prime importance in studies of basalt petrogenesis and the chemical processing of the mantle while such mechanics include the migration of melts and the convective physical admixture of differentiated material1 the role of fluids as transport agents has attracted much interest especially in regions affected by kimberlitic activity2 4 continental basaltic volcanism5 6 and in areas of subduction related magmatic activity7 8 the observation that many incompatible elements are readily leached from garnet lherzolites by dilute acid treatment3 has led to the assumption that a proportion of these elements is located on grain boundaries rather than in solution in the various minerals present this indirect evidence is reinforced by comparison of the compositions of mineral separates with their bulk parental material4 8 11 although careful electron microprobe analyses have made it possible to detect minor and trace elements within grains12 the low concentrations involved together with the high x ray background of the electron microprobe have made it impossible to investigate the supposed distribution of incompatible trace elements on grain boundaries we have measured directly using a high resolution proton microprobe9 10 the distribution of sr and other elements in a garnet lherzolite xenolith the analyses demonstrate that in this sample sr is preferentially concentrated along grain boundaries