geochemistry of the upper triassic black mudstones in the qiangtang basin tibet implications for paleoenvironment provenance and tectonic setting abstract the qiangtang basin is the largest mesozoic marine basin in the tibetan plateau the upper triassic black mudstones are among the most significant hydrocarbon source rocks in this basin here we present geochemical data for the upper triassic black mudstones to determine their paleoenvironment conditions provenance and tectonic setting to achieve these 30 black mudstones formed in various sedimentary environments were collected from the zangxiahe zana and bagong formations the results show that the total ree concentrations of mudstones from these formations range from 169 to 214 ppm 204 to 220 ppm and 141 to 194 ppm respectively all samples have chondrite normalized ree patterns with enrichment of lree depletion of hree and negative eu and ce anomalies specifically mudstones from the bagong formation exhibit higher negative eu anomalies and lower ree contents than those from the zangxiahe and zana formations mudstones from the zangxiahe and zana formations with low sr ba and sr cu ratios indicate the humid climate whereas the high sr ba and sr cu ratios of rocks from the bagong formation suggest the arid climate the low u th cu mo zn v cr and ni co ratios of rocks from the zangxiahe zana and bagong formations are indicators of oxidized conditions the bivariate diagrams tio2 vs al2o3 tio2 vs zr la th vs hf and co th vs la sc reveal that mudstones from the zangxiahe and zana formations were potentially derived from intermediate igneous rocks whereas mudstones from the bagong formation were probably sourced from felsic igneous rocks their source rocks are mostly deposited in the collisional setting ree of mudstones from the zangxiahe zana and bagong formations were possibly originated from terrigenous detritus with minor non terrigenous contributions into the zana samples the ree contents of these mudstones are controlled mainly by terrigenous detrital minerals rather than by the paleoclimate paleoredox conditions or organic matter however calcite minerals could dilute ree therefore the ree contents of the bagong formation mudstones are significant lower than those of the zangxiahe and zana formations mudstones

rare earth element redistribution and its effects on the neodymium isotope system in the austin glen member of the normanskill formation new york usa abstract three groups of ree patterns are observed for the sandstones and shales of the middle ordovician austin glen member of the normanskill formation one sandstone sample is enriched in middle and light rare earth elements the majority of samples are light rare earth element lree enriched with negative eu anomalies and flat heavy rare earth elements hrees whereas a third group appears to have lost lrees and middle rare earth element mrees homogeneous neodymium isotopic compositions for all samples at about the time of deposition nd 470 ma 8 2 1 1 2sd indicate that the source of the austin glen member was well mixed and that the neodymium had a long term enriched history the differences in the shape and abundances of the ree patterns combined with the neodymium isotope characteristics of the samples lead us to the conclusion that samarium and neodymium were fractionated and that the neodymium isotopic system might have been disturbed at about the time of deposition 470 ma most samples appear to have been affected by this process the two most altered shales lost about half of their neodymium and their sm nd ratios are higher than the sm nd ratios of average shales these two shales give clearly erroneous mantle extraction ages but the average tdm of the provenance can still be deduced 1700 1800 ma from the least disturbed sandstones with normal upper crustal sm nd ratios accordingly this study demonstrates that the rees may be transported and neodymium isotopes may be reequilibrated under certain sedimentary conditions e g diagenesis however in spite of evidence for ree redistribution provenance information tdm original ree patterns may still be inferred

the genesis of coal from the viewpoint of coal petrology abstract the genesis of the microscopic constituents of coal macerals and of maceral associations microlithotypes representing various coal facies is discussed in the light of recent advances that have been made in the study of coals and modern peats peat microscopy especially promoted the understanding of humification and biological gelification both of which are decisive for the genesis of huminites vitrinites in brown coals and hard coals respectively microbial activity during peatification has been documented by chemists microbiologists and petrologists and recently by electron microscopical observations in coals this activity leads to the incorporation of lipid substances into the humic matter and later influences the chemical physical and technological properties of vitrinites geochemical gelification transforms the huminites of brown coals into the vitrinites of bituminous coals and is probably caused by the onset of bitumen generation in coal in this process the hydrogel brown coal is transformed to the bitumogel bituminous coal coal as a source rock for oil has become an important research subject for coal petrologists and oil exploration the formation of more or less liquid bitumen and its later cracking to gaseous hydrocarbons leads to the coalification jumps of the macerals especially liptinites and vitrinites and to the generation of secondary macerals like exsudatinite bitumen and micrinite dead carbon bituminization in coal has been revealed by the use of fluorescence microscopy which also found the presence of new liptinite macerals bituminite fluorinite and exsudatinite and suggests a higher proportion of algal material in coals than was thought earlier the genesis of various types of inertinite macerals will probably become an increasingly important subject of research especially with regard to rank inertinites that seem to attain their high inertinitic reflectance initially during coalification besides the origin of macerals the origin of various coal facies in terms of maceral associations is considered in relation to the palaeogeographic depositional milieu the peat forming vegetation palaeoclimate water and nutrient supply acidity marine and calcareous influence and fire with examples from euramerican carboniferous coals gondwana coals and tertiary brown coals vegetation water and oxygen supply eh conditions are most important for the generation of coal facies vegetation has been reconstructed with the help of palaeobotany including palynology cuticular analysis and wood anatomy in brown coals and with the study of petrified permineralized peats preserved in coal balls the microscopical investigations of botanically recognizable plant remains isolated from coals or accompanying rocks has been especially informative however the results of palynological and cuticular analyses should be evaluated with caution considering the varying resistance of palynomorphs and cuticles and in the case of palynomorphs their possible extrapaludal origin microscopical studies of modern peats that were derived from different types of vegetation growing in different hydrological environments have been very helpful in interpreting coal facies especially in brown coals the much disputed origin of brown coal lithotypes is considered in detail for hard coals there seems to be agreement that coal layers rich in vitrites and liptinite poor clarite were deposited in wet forest swamps that microlayered liptinite rich clarites are sub aquatic humic muds and that inertinite rich durites represent oxidized peats the origin of liptinite rich durites is controversial either subaquatic muds or oxidized peats the latter perhaps from raised bogs a recent trend in the literature is the assumption that many if not all mineable coal seams have been deposited in raised bogs under ombrogenous oligotrophic conditions although raised bogs with a dense arborescent vegetation are known from borneo it seems not probable that most seams which were deposited in foredeeps or steadily sinking graben zones are of ombrogenous origin although a succession from relatively wet and eutrophic to relatively dry and oligotrophic conditions may be true for occasional seams but as in modern peats striking changes of coal facies are commonly caused by hydrological events e g inundations as a consequences of crevasses or of fires that burned the peat the origin of the inertinite rich gondwana coals is discussed in relation to their specific climatic conditions and a comparison with sub arctic peats is recommended coals influenced by marine and calcareous conditions are characterized by high contents of sulfur and pyrite as well as by hydrogen rich vitrinites with a relatively low reflectance and high fluorescence all due to a strong bacterial activity in peats of low acidity proposals for further research are made in the conclusions

paleosols below the ames marine unit upper pennsylvanian conemaugh group in the appalachian basin u s a variability on an ancient depositional landscape abstract a vertisol like paleosol complex ranging from 3 to 10 m thick is developed below the ames marine interval conemaugh group upper pennsylvanian in the appalachian basin eastern ohio western pennsylvania west virginia and adjacent parts of maryland and kentucky sub ames mudstones contain the following pedogenic features very large slickensides microsparitic calcite nodules nodules or coatings of radial calcite spar preserved soil microstructure soil compatible birefringence fabrics and prominent mottling commonly restricted to the lower part of the paleosolum soil formation comprised 1 long term pedogenesis in alluvial and probably lacustrine sediments and 2 rapid development of histosols harlem coal as much as 8 m thick encouraged by the approaching am s transgression pedogenic carbonates in the sub ames interval at three localities yielded 18o values ranging from 6 18 to 1 21 pdb average 4 02 pdb s d 1 42 and 13c values ranging 9 17 to 6 72 pdb average 8 12 pdb s d 0 59 a inary plot of these values suggests mixing probably seasonal of evaporative and meteoric effects on isotope partitioning the stratigraphy of the ames harlem coal interval the regional distribution and thickness of the harlem coal and features of the sub ames paleosol show that the pre ames landscape had significant local relief in the form of shallow paleovalleys with broad interfluves along the western to northern margin of the appalachian basin ohio southwestern pennsylvania the stratigraphic relationships of sub ames paleosols the harlem coal ames marine unit interval and the ames marine unit itself are compatible with a significant effect of eustatic sea level rise in this area greater regional tectonic subsidence was probably the strongest control on sub ames sedimenta ion and pedogenesis along the eastern to southern margin south central pennsylvania west virginia northeasternmost kentucky where there appears to have been very little relief the morphology and stable isotope geochemistry of sub ames paleosols are compatible with seasonally wet dry climates probably with moderate 500 1000 mm annual rainfall

rare earth element distribution in lake tyrrell groundwaters victoria australia abstract the rare earth element ree geochemistry of the saline to hypersaline acidic brines of lake tyrrell victoria australia were analyzed in order to determine the relative importance of concentration and modification processes in the lake system several types of brines were identified on the basis of different ree patterns and concentrations regional groundwater flowing into lake tyrrell yields the highest concentrations of ree while a transitional water group is identified on the basis of lower ree concentrations a third water group the reflux brine is characterized by extremely low ree concentrations the ree patterns suggest that ree are introduced to the lake tyrrell system by the regional groundwater which has concentrated ree from the aquifer material in its acidic waters eventually ree are removed from the evolving water mass as higher levels of ph are reached the data of the study strongly suggest that ree are scavenged from solution by fe oxyhydroxide phases which precipitate as the ph of the system rises water rock interactions probably control ph in the lake system and therefore ultimately control the concentration of ree in solution in this system our results are directly correlated with studies of hydrothermal vents and geothermal solutions which have shown the concentration of ree in solution to be dominantly controlled by ph

rb sr sm nd and pb isotope systematics of pyrite implications for the age and genesis of lode gold deposits lode gold deposits commonly consist of pyrite and lesser amounts of lead and zinc sulfides accompanied by quartz and calcite their exact origin remains controversial mainly because of the scarcity of reliable geochronological data here we present direct rb sr dating of pyrite from a lode gold deposit and propose the method as a useful geochronological technique for gold mineralization for which age data are poor a positive correlation between present day 87 sr 86 sr and 87 rb 86 sr ratios of pyrite fes 2 subsamples from the linglong gold mine of china corresponds to an age of 122 123 ma which dates the age of gold mineralization the sr nd and pb isotopic compositions of pyrites and the associated rocks suggest that the hydrothermal fluids responsible for the pyrite and gold mineralization were probably derived from a mixed source i e degassing of mafic magmas and meteoric water that had leached the country rocks

depositional environments and cyclicity of the early ordovician carbonate ramp in the western tarim basin nw china abstract during the early ordovician the tarim basin nw china was mainly occupied by an extensive shallow water carbonate platform on which a carbonate ramp system was developed in the bachu keping area of the western part of the basin three well exposed typical outcrop sections of the lower ordovician penglaiba formation were investigated in order to identify the depositional facies and to clarify origins of meter scale cycles and depositional sequences thereby the platform evolution thirteen lithofacies are identified and further grouped into three depositional facies associations peritidal restricted and open marine subtidal facies these lithofacies are vertically stacked into meter scale shallowing upward peritidal and subtidal cycles the peritidal cycles are mainly distributed in the lower and uppermost parts of the penglaiba formation deposited in the inner middle ramp and commonly start with shallow subtidal to intertidal facies followed by inter to supratidal facies in contrast the subtidal cycles occur throughout the formation mostly in the middle outer ramp and are dominated by shallow to relatively deep i e intermediate subtidal facies the dominance of asymmetrical and incomplete cycles suggests a dominant control of earth s orbital forcing on the cyclic deposition on the platform on the basis of vertical facies and cycle stacking patterns and accommodation changes illustrated by the fischer plots from all studied sections five third order depositional sequences are recognized in the penglaiba formation individual sequences comprise a lower transgressive part and an upper regressive one in shallow water depositional environments the transgressive packages are dominated by thicker than average subtidal cycles indicating an increase in accommodation space whereas regressive parts are mainly represented by thinner than average peritidal and subtidal cycles denoting a decrease in accommodation space in contrast in intermediate to deep subtidal environments transgressive and regressive packages display an opposite trend in accommodation space changes sequence boundaries except the basal and top boundaries of the penglaiba formation are usually represented by laterally traceable transitional boundary zones without apparent subaerial exposure features good correlation of the long term changes in accommodation space or sea level inferred from vertical stacking patterns of facies and cycles suggests an overriding eustatic control on the formation of meter scale cycles and third order depositional sequences as well as platform evolution superimposed with local and or regional tectonic influence during the early ordovician this study would help understand the controls on the tempo spatial facies distribution stratal cyclicity and carbonate platform evolution in the western tarim basin during the early ordovician facilitating prediction for favorable subsurface carbonate reservoirs and future hydrocarbon exploration and production in the penglaiba formation

depositional history of the fire clay coal bed late duckmantian eastern kentucky usa more than 3800 coal thickness measurements proximate analyses from 97 localities and stratigraphic and sedimentological analyses from more than 300 outcrops and cores were used in conjunction with previously reported palynological and petrographic studies to map individual benches of the coal and document bench scale variability in the fire clay hazard no 4 coal bed across a 1860 km 2 area of the eastern kentucky coal field the bench architecture of the fire clay coal bed consists of uncommon leader benches a persistent but variable lower bench a widespread and generally thick upper bench and local variable rider benches rheotrophic conditions are inferred for the leader benches and lower bench based on sedimentological associations mixed palynomorph assemblages locally common cannel coal layers and generally high ash yields the lower bench consistently exhibits vertical variability in petrography and palynology that reflects changing trophic conditions as topographic depressions infilled infilling also led to unconfined flooding and ultimately the drowning of the lower bench mire the drowned mire was covered by an air fall volcanic ash deposit which produced the characteristic flint clay parting the extent and uniform thickness of the parting suggests that the ash layer was deposited in water on a relatively flat surface without a thick canopy or extensive standing vegetation across most of the study area ash deposits led to regional ponding and establishment of a second planar mire because the topography had become a broadly uniform nutrient rich surface upper bench peats became widespread with large areas of the mire distant to clastic sources vertical sections of thick 70 cm low ash yield upper coal bench show a common palynomorph change from arborescent lycopod dominance upward to fern and densospore produc ing small lycopod dominance inferred as a shift from planar to ombrotrophic mire phases domed mires appear to have been surrounded by wide areas of planar mires where the coal was thinner 70 cm higher in ash yield and dominated by arborescent lycopods rectangular

rare earth element sources and modification in the lower kittanning coal bed pennsylvania implications for the origin of coal mineral matter and rare earth element exposure in underground mines abstract in this study we examine the variations in rare earth elements ree from the lower kittanning coal bed of eastern ohio and western pennsylvania usa in an attempt to understand the factors that control mineral matter deposition and modification in coal and to evaluate possible ree mixed exposure hazards facing underground mine workers the results of this study suggest that the lower kittanning coal mineral matter is derived primarily from a clastic source similar to that of the shale overburden while highly charged cations like silicon aluminum and titanium remained relatively immobile within the coal mineral matter iron primarily as pyrite was added from nonclastic sources either during deposition of the coal mire vegetation or subsequent to burial other mobile cations e g alkali and alkaline earth elements appear to have been added to and or leached from the originally deposited clastic mineral matter most of the sulfur in the lower kittanning coal bed is bound as fes2 in the mineral matter but a majority of samples contain a small excess of s that is most likely organically bound in general the total rare earth element content tree in coal ash is greater than that in the shale overburden if the primary source of mineral matter is the same as that for the overlying shale then ree must have been enriched in the coal mineral matter subsequent to deposition the total rare earth element content of lower kittanning coals correlates strongly with si concentration tree 0 0024 si which provides a threshold for evaluating possible mixed exposure health effects chondrite normalized ree patterns reveal a shale like light rare earth element lree enrichment for the coal similar to that of the shale overburden again suggesting a primarily clastic ree source however when normalized to the shale overburden most of the coal ash samples display a small but distinct heavy rare earth element hree enrichment we surmise that the hree were added and or preferentially retained during epigenesis possibly associated with groundwater flow through the coal unit but not necessarily in close association with the addition of iron at least some of the excess hree could be organically bound within the lower kittanning coal

facies development in the lower freeport coal bed west central pennsylvania u s a abstract the lower freeport coal bed in west central pennsylvania is interpreted to have formed within a lacustrine mire environment conditions of peat formation caused by the changing chemical and physical environments produced five coal facies and two mineral rich parting facies within the coal bed the coal bed facies are compositionally unique having developed under varying conditions and are manifested by megascopic petrographic palynologic and quality characteristics the initial environment of the lower freeport peat resulted in a coal facies that is relatively high in ash yield and contains large amounts of lycopod miospores and moderate abundances of cryptotelinite crypto gelocollinite inertinite and tree fern miospores this initial lower freeport peat is interpreted to have been a topogenous body that was low lying relatively nutrient rich mesotrophic to eutrophic and susceptible to ground water and to sediment influx from surface water the next facies to form was a ubiquitous clay rich durain parting which is attributed to a general rise in the water table accompanied by widespread flooding following formation of the parting peat accumulation resumed within an environment that inhibited clastic input development of doming in this facies restricted deposition of the upper shale parting to the margins of the mire and allowed low ash peat to form in the interior of the mire because this environment was conducive to preservation of cellular tissue this coal facies also contains large amounts of crypto telinite this facies development is interpreted to have been a transitional phase from topogenous planar peat formation to slightly domed oligotrophic nutrient poor peat formation as domed peat formation continued fluctuations in the water table enabled oxidation of the peat surface and produced high inertinite concentrations toward the top of the coal bed tree ferns became an increasingly important peat contributor in the e upper facies based on the palynoflora this floral change is interpreted to have resulted from the peat surface becoming less wet or better drained a condition that inhibited proliferation of lycopod trees accumulation of the peat continued until rising water levels formed a freshwater lake within which clays and silts were deposited the development of the lower freeport peat from a planar mire through transitional phases toward domed peat formation may be an example of the type of peat formation of other upper middle and upper pennsylvanian coal beds

paleoclimate controls on late paleozoic sedimentation and peat formation in the central appalachian basin u s a abstract in the central appalachian basin at least two major climate changes affected sedimentation during the late paleozoic stratigraphically these two changes are indicated by the distribution of coal beds the variation in coal quality and the variation in rock lithologies in latest mississippian or earliest pennsylvanian time the climate changed from dry seasonal tropical to ever wet equable tropical the equable climate prevailed into the middle pennsylvanian influencing the morphology and geochemistry in peat forming environments many of the peat deposits which formed under the equable climate were probably domed raised bogs low concentrations of dissolved solids in peat formation water resulted in low buffering capacity organic acids caused acidic ph another climate change occurred in late middle pennsylvanian time when evapopation periodically exceeded rainfall resulting in an increase of both dissolved solids and ph 4 to 7 in surface and near surface water throughout the remainder of the pennsylvanian the surfaces of peat deposits were probably planar not domed water in peat forming and other depositional environments became more nearly neutral the coal beds derived from these peats are highly variable in both ash and sulfur contents drier or more seasonal climates are also indicated by sequences of 1 calcareous sandstone and shale 2 nonmarine limestone that shows shallow water and subaerial exposure features and 3 calcareous paleosols that have caliche characteristics our data and observations indicate that physical depositional environment models for the origin of coal do not adequately explain variations in mineral matter content and composition in commercial quality coal beds in the central appalachian basin stratigraphic variation in mineral matter in coal beds and in syngenetic and early diagenetic minerals in rocks associated with the coal beds appears to be better explained by changes in geochemical conditions of nonmarine sedimentation paleoclimate was a principle control on these geochemical conditions

geochemistry of major and trace elements in permian coal with an emphasis on no 8 coal seam of zhuji coal mine huainan coalfield china a better understanding on geochemistry of elements in coal has both environmental and geological implications in this study 53 coal samples were collected from no 8 coal seam of the zhuji coal mine huainan coalfield the concentrations of 49 elements ash yield and total organic compound toc as well as mineralogical phases in coal were determined as compared with chinese the usa and world coals si k se cd sn sb and w in studied coal seam are higher whereas zn as and lu are lower the enrichment factor and concentration coefficient show that se cd sn sb and w are preferably enriched in studied coals the enrichment of se and cd is probably attributed to their higher proportions of organic forms most major and trace elements tend to concentrate in either the upper or lower sections of coal seams which suggest that depositional micro environment was important in controlling elements migration and enrichment the correlation analysis of elements with ash yield shows that the behavior of elements in coal follows the periodic change of metallic activity the modes of occurrence of major and trace elements are elaborated by statistical methods silicon is mainly in form of montmorillonite or presents as free quartz iron is associated with chlorite siderite lepidocrocite and other iron bearing minerals ti shows obviously organic association three groups of elements are divided in accordance with the cluster dendrogram group 1 sc hree be y v co cu p sr b sn se bi toc s ba as group 2 lree zn al mn li na th cr fe mg and group 3 ca mo si w ad ti pb k many trace elements including li sc v cr zn sr la ce nd sm eu gd tb lu pb bi and th correlate positively with al suggesting their occurrence mainly in clay such as kaolinite and chlorite ree in the studied coalfield was primarily supplied by terrestrial clastics coming from north china coal basin the differentiation of lree and hree is probably attributable to their different physicochemical characterisitcs and specific paleo sedimentary environment various indexes e g b content ash index c value and the existence of certain minerals suggest a reducing and anoxic sedimentary environment of coal swamp with a stable supply of terrigenous detrital materials in a moist environment the origins of enriched elements are primarily derived from the source rock sedimentary environment and thermally contact metamorphism or possibly magmatic hydrothermal fluids

paleoecological interpretation of a middle pennsylvanian coal bed in the central appalachian basin u s a abstract at least 180 small spore species assignable to 62 miospore genera have been identified from the middle pennsylvanian hernshaw coal bed in southern west virginia and its stratigraphic equivalent the fire clay coal bed in eastern kentucky the established natural affinities of a majority of these miospore taxa indicate that the hernshaw fire clay peat swamp supported a diverse flora consisting of arborescent and herbaceous lycopods ferns tree like and small varities calamities and cordaites four floral groupings are recognized in the hernshaw fire clay coal bed the inferred paleoecology and vertical stratification of each of these four floral groupings is similar in structure to the phasic floral communities found in modern domed peat systems suggesting that the ancient hernshaw fire clay peat swamp was a domed deposit compositional characteristics petrographic make up ash yield and sulfur content associated with the four groupings are consistent with and support this interpretation where uninterrupted by inorganic partings the hernshaw fire clay coal bed commonly contains basal coal layers dominated by lycospora bearing arborescent lycopods with successive increments showing a progression to a more fern and herbaceous lycopod dominant flora in younger layers these observations are corroborated by petrographic analyses which show the bed to be compositionally stratified increments dominated by lycospora have high vitrinite contents in contrast to increments containing increased percentages of fern and herbaceous lycopod affiliated taxa that are enriched in inertinite macerals the volcanic ash fall preserved as the flint clay parting in the hernshaw fire clay coal bed had a considerable effect on the development of the ancient hernshaw fire clay peat swamp besides interrupting peat formation the presence of an inorganic substrate represent a major change in edaphic conditions within the swamp this disruption is demonstrated by a change in palynflora and by the establishment and proliferation of some plant groups notably cordaites and calamites that may have been better adapted to growth on mineral soils these palynologic and petrographic relationships thought to be indicative of a domed peat swamp origin are not confined to the hernshaw fire clay coal bed but appear to be characteristic of many coal beds in the appalachian basin and also of coal beds in other basins

neodymium isotopes in planktonic foraminifera a record of the response of continental weathering and ocean circulation rates to climate change the neodymium nd isotope composition of ancient seawater is a potentially useful tracer of changes in continental inputs and ocean circulation on timescales of a few ka here we present the first nd isotope record for seawater using sedimentary foraminifera cleaned using standard oxidative reductive techniques the data along with mn ca ratios suggest that cleaned foraminifera provide a reliable record of nd in seawater and hold out the prospect of using nd in foraminifera to examine changes in seawater that accompany glacial interglacial climatic cycles the principal potential problem to be overcome with the use of forams as records of trace elements in ancient seawater is their diagenetic fe mn coatings these contain large amounts of nd and other trace elements but can be cleaned off using highly reducing reagents mn ca ratios for the majority of the cleaned sedimentary foraminifera analysed here lie within the range 10 100 mol mol that has yielded success in studies of transition elements in forams mass balance modelling suggests that for residual mn ca ratios 100 mol mol nd added to the foram in the coating will never shift the measured nd isotope composition significantly away from the seawater value acquired by the foram test in the water column additionally nd concentrations measured in cleaned sedimentary foraminifera are comparable with those for a modern sample that has never encountered diagenetic fluids finally core top planktonic foraminifera for two sites have nd isotope compositions that are identical to local surface seawater the data we present here for labrador sea forams over the past 2 5 m y are interpreted in terms of changes in the seawater isotopic composition the data show a pronounced shift from end values of 12 to 19 in the period 2 5 1 5 ma this change is interpreted to result from the initiation of northern hemisphere glaciation and the increased derivation of labrador sea nd via ice rafting from archaean terranes in central canada in combination with stable isotope and foraminiferal relative species abundance data the new nd data are consistent with the surface hydrography of the labrador sea being dominated by a fluctuating balance between cold polar waters containing unradiogenic nd and warm subtropical waters containing more radiogenic nd the major change in labrador sea nd that is observed in the past 2 5 ma can on its own account for the change in the nd isotope composition of north atlantic deep water over the same time period

rare earth element resources in coal mine drainage and treatment precipitates in the appalachian basin usa abstract drainages from abandoned coal mines in the appalachian basin represent a potential source of rare earth elements and yttrium rey many of which are considered to be critical resources due to their use in electronics and batteries we report rey data from coal mine drainage cmd sites and precipitates from cmd treatment systems throughout pennsylvania most cmd discharges are enriched in total rare earth elements relative to concentrations expected in unaffected surface or ground waters generally by 1 4 orders of magnitude relative to the north american shale composite nasc which approximates the rock with which mine waters interact cmd waters generally show a pattern of enrichment in the middle ree including several identified as critical resources nd eu dy tb low ph discharges tend to have higher rey concentrations than circumneutral discharges and a precipitous drop in concentration around ph 6 6 suggests adsorption of rey in the mine water flow path at near neutral ph values treatment precipitates including fe oxy hydroxides ca mg lime slurries and si and al rich precipitates are enriched in rey relative to the average cmd discharge value by factors of 103 104 while the discharges and precipitates analyzed in this study did not overlap in space and time the overall rey pattern of the precipitates approximate those of the cmd but with a slight depletion in light rare earth elements the higher rey concentrations in precipitates from systems treating low ph discharges most likely reflects the generally higher rey concentrations in these discharges but this needs to be established through direct comparisons over multiple seasonal cycles we estimate that coal mine drainage outflows in the appalachian basin generate a total of about 538 metric tons of rey per year in a dissolved state with 83 of that from low ph

geochemical systematics and precious metal content of the sedimentary horizons of lower gondwanas from the sattupalli coal field godavari valley india abstract major trace rare earth ree and platinum group elements pge have been analysed from the carbonaceous horizons of permian barakar formation of sattupalli coal field of godavari valley to understand the provenance and depositional environment barakar formation of coal field consists of sandstone siltstone carbonaceous shale and coal seams coal is enriched in trace elements compared with the clarke s background values ferromagnesian trace elements ni cr and co are similar in range in both coal and carbonaceous shales along with large ion lithophile elements lile rb sr cs and ba high field strength elements hfse nb ta zr and ti light ree lree la sm and ag archean upper crust auc normalized ree and multielement variation patterns of the coal show a flat ree with a slight depletion in ce and eu contents in most of the samples their multielement patterns exhibit enrichment of th and u negative ta zr hf and positive ti anomalies pronounced positive anomaly occurs at zr hf and ti that are combined with both positive and negative nb and ta anomalies in carbonaceous shales and clay sandstones have a high sio 2 50 80 wt low fe 2 o 3 al 2 o 3 and moderately high k 2 o contents auc normalized ree patterns are almost flat with slight negative to no eu anomalies followed by small negative ce anomalies ce ce 0 87 0 95 with one exception their multielement patterns exhibit positive u small negative nb ta a pronounced positive zr hf anomaly followed by negative ti and v anomalies enrichment of both zr and tio 2 in some samples reflects on the mafic and felsic sources at the source region the fractionated ree patterns hree enrichment and negative eu anomalies are consistent with contribution of zircon through felsic source nb ta troughs endorse their inheritance from schistose rocks of eastern ghats complex the high al 2 o 3 yb and th yb ratios along with negative eu anomalies reflect on the ttg felsic rocks of provenance based on the geochemical available petrological and paleocurrent analysis indicate the source rocks of the barakar formation were granite granitic gneiss high grade metamorphic rocks from eastern ghats and basic rocks the provenance is located west and south east i e partly peninsular gneiss and partly eastern ghat complex the au pge contents of sattupalli coalfield have been deposited through ne sw trending post depositional transverse faults that have affected all the gondwana formations during the early cretaceous the mafic rocks present within the basement could have been the source of these elements

the geochemistry of rare earth elements in the amazon river estuary abstract the estuarine geochemistry of rare earth elements rees was studied using samples collected in the amazon river estuary from the amasseds amazon shelf sediment study cruise of august 1989 extensive removal of dissolved 0 22 m filtered trivalent rees from river water occurs in the low 0 6 salinity region removal by the salt induced coagulation of river colloids leads to fractionation among the ree iii series the order of removal is light rees middle rees heavy rees there also is the enhanced removal of ce relative to trivalent la and nd in the low salinity 0 6 zone and in the zone of high biological activity this is the first field observation of strong ce removal associated with coagulation of river colloids and biological productivity the argument is made that the decrease in the ce anomaly across a biological front is caused by biologically mediated oxidation of ce iii to ce iv coagulation of river colloids and biologically mediated oxidation of ce iii lead to fractionation of ree iii and redox modification of ce these processes result in the ree composition becoming fractionated relative to the amazon river water and crust and more evolved toward the ree composition of the oceans this study implies that reactions in estuaries play significant yet poorly understood roles in controlling the ree composition and ce anomaly of the oceans

distributions and associations of selected trace elements in the lower kittanning seam western pennsylvania u s a abstract trace elements within the lower kittanning seam western pennsylvania show significant basinal variations many of these variations can be related to differences in the depositional environments of the peat as inferred by the nature of the overlying shales in that the distribution of minerals in this seam particularly that of clay minerals is controlled by depositional environment chromium cu v and zr show significant increases towards the northwestern and southeastern margins of the basin these trends can be explained by an association with clay minerals cr v and in part cu or with minor amounts of other detrital minerals zr clay composition of the lower kittanning seam reflects proximity to the sediment source and stability of the various clay minerals in the swamp environment kaolinite which increases in concentration towards the basin margins is primarily authigenic and shows a distribution that reflects the stability of this mineral in the relatively low ph freshwater areas of the peat swamp in this seam illite mica is predominantly detrital as inferred by polytype studies and increases along isolated sections of the basin margins where a greater detrital influx was experienced within the beryllium and ni also increase towards the basin margins these elements may have been trapped at the margins of the basin by the organic fraction of the peat or coal similarly cu may owe its distribution at least in part to organic trapping a decrease in be content along the southeastern margin of the basin may be due to the increase in coal rank observed in that area no basin wide trends were seen for ba mn and zn and their concentrations are controlled by local mineral occurences manganese variations for example can be related to local occurrences of siderite

paleobotanical and paleoecological constraints on models of peat formation in the late carboniferous of euramerica abstract the dominant plants of the late carboniferous lowland tropics were taxonomically and structurally distinct from those of any later time periods dominance was distributed among lycopsids ferns sphenopsids pteridosperms and cordaites and each of these groups had distinctive and different ecological preferences and amplitudes peat forming habitats were dominated by lycopsids throughout the westphalian with a significant cordaitean element in the middle westphalian during the stephanian tree ferns were dominant following major extinctions near the westphalian stephanian transition each of the major plant groups had distinctive architectures and tissue composition trees contributed up to 95 of the peat biomass and tree forms of lycopsids psaronius and medullosa lack good modern analogues the cordaites were the only woody plant group to contribute significantly to peat and then only during the mid westphalian structurally wood like lycopsid bark is the major woody tissue encountered in most westphalian coals tree ferns and pteridosperms were largely parenchymatous in construction the stigmarian root systems of lycopsids also were largely parenchymatous the tissue structure of these dominant plant suggests the need for extreme caution in the inference of mire ecological conditions or vegetational structure from coal petrographic data peat formed under arborescent ferns or pteridosperms or peat repeatedly exposed to decay and rerooting by stigmarian root systems of lycopsids would have a distinctly non woody signature and yet would have formed in a forested environment a summary is presented of the autecology and synecology of mire plants emphazing the structural framework provided by lycopsids during the westphalian certain constraints in the links between peat biomass and miospore palynology are discussed in terms of over representation under representation and non representation the formulation of smith s four phase hydroseral model is discussed and compared with more recent data available from plant paleoecology the current debate over an ombrotrophic vs rheotrophic origin of late carboniferous peats relies in large part on paleobotanical data almost entirely palynological in combination with petrographic analyses ecological studies of miospores and of coal ball and compression macrofossils and the linkage of miospores to source plants permit the re evaluation of mire successional models evidence for tree lycopsids sphenopsids pteridosperms and cordaites suggests growth mainly in rheotrophic mires tree ferns are likely candidates for growth in domed mires although evidence is ambiguous and some tree ferns clearly grew under rheotrophic conditions densospores produced by at least sporangiostrobus lycopsid subtrees have been considered diagnostic of ombrotrophic conditions abundant evidence refutes this simplistic interpretation and suggests broad ecological amplitudes for densospore producers including growth under rheotrophic conditions although plant fossils alone can not resolve most of the major debates in modern coal geology paleobotany does contribute significantly to our understanding of ancient mires an approach combining paleobotanical data with petrography sedimentology and geochemistry on a case by case basis is most likely to produce a clear picture

reverse drag revisited why footwall deformation may be the key to inferring listric fault geometry abstract although reverse drag the down warping of hanging wall strata toward a normal fault is widely accepted as an indicator of listric fault geometry previous studies have shown that similar folding may form in response to slip on faults of finite vertical extent with listric or planar geometry in this study we therefore seek more general criteria for inferring subsurface fault geometry from observations of near surface deformation by directly comparing patterns of displacement stress and strain around planar and listric faults as predicted by elastic boundary element models in agreement with previous work we find that models with finite planar planar detached and listric detached faults all develop hanging wall reverse drag folds all of these model geometries also predict a region of tension and elevated maximum coulomb stress in the hanging wall suggesting that the distribution and orientation of near surface joints and secondary faults may also be of limited utility in predicting subsurface fault geometry the most notable difference between the three models however is the magnitude of footwall uplift footwall uplift decreases slightly with introduction of a detachment and more significantly with the addition of a listric fault shape a parametric investigation of faults with constant slip ranging from nearly planar to strongly listric over depths from 1 to 15 km reveals that footwall fold width is sensitive to fault geometry while hanging wall fold width largely reflects fault depth application of a graphical approach based on these results as well as more complete inverse modeling illustrates how patterns of combined hanging wall and footwall deformation may be used to constrain subsurface fault geometry

the incorporation of rare earth elements in modern coral we report measurements of rare earth elements rees which show that these trace elements are being incorporated in modern coral in proportion to their seawater concentrations four bermuda north rock coral species diploria strigosa diploria labyrinthiformis montastrea annularis and porites astreoides and two tarawa atoll samples of the species hydnophora microconos were analyzed by ti idms following cleaning techniques to isolate the lattice bound rees based on the replicate analyses of the same piece of diploria strigosa excellent reproducibility was achieved the ree ca ratios 0 1 3 nmol mol of the bermuda and tarawa corals are similar to those of cd ca the trace metal with the lowest seawater concentration used in coral studies with the exception of ce the distribution coefficients e g dnd nd coral nd seawater ca seawater ca coral between bermuda coral lattice and sargasso seawater have fairly flat patterns across the ree series the values of d range from 1 to 3 like those reported for other trace elements in corals this suggests but does not prove that rees are incorporated in the aragonite lattice of these corals the shale normalized ree patterns of the tarawa corals also have seawater like distributions however no local seawater data are available to calculate values of d two bermuda species d labyrinthiformis and p astreoides have values of d for ce that are high with respect to the d values of la and nd implying that there is preferential uptake of ce into the lattice this may be related to the fact that ce is the only ree with an active redox chemistry in seawater there is considerable interest in using the chemical and isotopic composition of coral as indicators of climatic variations the combination of ree ca ratios and neodymium isotopic composition of coral has the potential to help understand important natural processes a primary application could be directed toward a tracer for river water discharge in tropical regions and by inference a proxy for rainfall climate variation and weathering history this application would exploit the fractionated composition of rees in river water as a terrigenous signature in coastal corals

correlation of carboniferous strata using a hierarchy of transgressive regressive units carboniferous strata can be described interpreted and correlated using six scales of allocyclic transgressive regressive t r units these t r units are inferred to be the net result of deposition during cycles of sea level change all pennsylvanian and lower permian strata constitute one second order t r unit or synthem the pennsylvanian system contains third fourth fifth and sixth order t r units that can be correlated across both marine and nonmarine facies in the appalachian basin this permits differentiation of allocyclic t r units from autocyclic t r units or fluvial autocyclic units the hierarchical approach is also useful for predicting the location of marine horizons coals claystones and various types of stratigraphic breaks a hierarchical scheme of allocyclic t r units could be combined with biostratigraphic radiometric and magnetostratigraphic data to form a practical chronostratigraphic framework for the carboniferous

rare earth element systematics of the chemically precipitated component in early precambrian iron formations and the evolution of the terrestrial atmosphere hydrosphere lithosphere system irrespective of provenance age and metamorphic grade the chemically precipitated component in early precambrian 2 3 ga iron formations ifs displays smyb cn 1 which reflects the corresponding ratios of contemporaneous seawater in conjunction with end if end shale jacobsen and pimentel klose 1988a b this rare earth element ree signature reveals that the ree distribution in early precambrian ifs must be explained by mixing between a marine bottom and a surface water component and that the rees and by analogy the fe cannot be derived from weathering of a continental source eusm n ratios of detritus free ifs are controlled by the marine bottom water component where eusm cn 1 results from ree input from high temperature high t hydrothermal fluids which received their ree signature during high t alteration of oceanic crust at spreading centres decreasing eusm cn of ifs with decreasing depositional age reflect the vaning importance of high t compared to low t 200 c hydrothermal fluids hence oceanic crust alteration for the ree budget of marine bottom waters and are related to decreasing upper mantle temperatures smyb n ratios of detritus free ifs are controlled by the marine surface water component whose ree distribution is affected by the same processes which operate today in the entire ocean mixing calculations reveal that smyb cn in early precambrian marine surface waters was significantly lower than it is today to explain this difference two mechanisms are discussed on the basis of higher pco2 and lower po2 levels of the precambrian atmosphere 1 1 higher co32 in precambrian river and coastal waters and 2 2 redox cycling of the rees at an oceanwide chemocline which separated anoxic and oxic water masses however these processes are synergetic and could have operated in unison the ree distribution in precambrian ifs is described as a result of mixing in a multicomponent system where high t and low t hydrothermal fluids contributed to the marine bottom water and ree input from the dissolved ree pool in river waters after some modification in estuaries dominated the ree distribution in marine surface waters after mixing of bottom and surface waters their combined ree load was quantitatively scavenged onto precipitating iron oxihydroxides or iron carbonates and deposited with the chemically precipitated component after addition of variable amounts of clastic detritus this eventually resulted in the ree distribution observed in precambrian ifs

isotopic evidence for the source of sulfur in the upper freeport coal bed west central pennsylvania u s a abstract sulfur isotopic variations were used to determine the sources of sulfur in a medium sulfur coal 2 wt s that lacked marine influence which is often cited as a major source of sulfur in coal variations in the amount and isotopic composition of the organic and pyritic sulfur among the coal bed facies of the upper freeport coal bed middle pennsylvanian are attributed to differential incorporation of syngenetic and epigenetic sulfur these variations reflect varying environmental conditions during paleopeat formation porosity and permeability and the availability of sulfate and iron a large increase in the abundance and sulfur isotopic value of pyritic sulfur in the upper facies of the coal bed in proximity to the overlying lacustrine shale corresponds to an increase in massive and irregular forms of pyrite this relationship is attributed to at least two stages of epigenetic pyrite incorporation an early stage of epigenetic pyrite moderately enriched in 34s apparently formed during the fluvial lacustrine period immediately following peat accumulation a late stage of epigenetic pyrite highly enriched in 34s formed after compaction of the original peat as cleat and fracture filling pyrite this sulfur was probably derived from bacterial reduction of dissolved sulfate in groundwater isotopic mass balance calculations indicate that this late stage epigenetic pyrite may account for up to 50 of the pyritic sulfur in some upper facies of the coal bed these results suggest that most of the pyritic sulfur in the upper freeport coal bed may be epigenetic incorporated either soon after peat accumulation or later during coalification

water rock interaction in an acidic mine discharge as indicated by rare earth element patterns abstract the rare earth element ree composition of an acidic spring discharging at ph 2 7 was studied in relation to the ree composition of selected extracts of the coal bearing strata hydrologically above the discharge the low ph of the discharge and the access to the strata through which it flows provides an excellent opportunity to study the use of rees as tracers of water rock interaction extraction techniques were used to mimic the process of acidic groundwater generation in coal bearing strata samples were treated to remove exchangeable ions and then treated sequentially with solutions buffered at ph 5 5 3 6 and 1 6 in order to mimic the natural buffering systems of groundwaters finally samples were oxidised with hydrogen peroxide in an attempt to remove the pyrite the results show that the composition of the spring is controlled by pyrite oxidation and buffering by fe oxy hydroxides the latter with compositions inherited from carbonates from within the sequence the similarity of ree patterns of the carbonate and the silicate extracts tends to obscure information concerning the relative roles of carbonate or silicate phases the source strata of the spring has evolved over time and shows that different coal seams have a unique contribution this distinct contribution appears more related to the mixture of sedimentary components i e carbonates silicates etc in the coal seam and the combination of shale and sandstone layers surrounding coal seams than the composition of the components themselves the similarity between ree compositions of the sequential extracts suggests that relationships discovered for this spring will be applicable elsewhere in the basin however this very property will hamper the use of such lithophilic elements in cases where characterisation of the source area is not possible

aspects of the geochemistry of rare earth elements in coal an experimental approach abstract many coals worldwide are slightly enriched in heavy rare earth elements hree relative to light rare earth elements lree as compared with chondrites and shales a factor contributing to this fractionation could be the ability of the hree to form complexes with organic compounds which are more stable than those of the lree in order to test this hypothesis experiments on the sorption of several light and heavy rare earth elements la ce sm eu gd ho er lu on xylain and humic acids were performed the sorption on xylain was found to be ph and time dependent maximum quantity was sorbed in the range of ph 3 to 5 sorption equilibrium was reached in 5 to 7 days the shape of the sorption isotherms for all ree studied were similar the maximum content sorbed for each ree was about 0 2 meq 0 5 g xylain when all ree were present in equal concentration in the initial solution the quantity sorbed was also 0 2 meqv 0 5 g xylain nearly the same quantity of na k ca and mg were displaced from the sorbent these results suggest a cation exchange mechanism in which na k ca and mg bound to cooh and oh groups were replaced by the ree cations the capacity of humic acids leached from xylain was found to be about 0 05 meq ree on 0 250 mg humic acids ha the individual ree were sorbed in nearly equal quantities

geochemistry of rare earth elements in a marine influenced coal and its organic solvent extracts from the antaibao mining district shanxi china twenty six samples including roof bottom and coal plies of a marine influenced coal bed were collected from the antaibao mining district shanxi china the rare earth elements rees were determined in solids and organic solvent extracts the distribution pattern showed three distinct patterns shale like lree rich and hree rich this is attributed to the variable microenvironment of peat forming swamp the degree of marine influences and different ree sources rees in the coal are mainly controlled by detrital minerals but also affected by seawater the chondrite normalized ree patterns of the organic solvent extracts are distinctly different from those of corresponding original coal samples which show a negative eu anomaly a depletion of middle rees and an enrichment of hrees the lrees in coal extracts are likely adsorbed by hydrogen containing functional groups and hrees are likely bonded to carbon atoms

trace and rare earth elemental variation in arabian sea sediments through a transect across the oxygen minimum zone we have determined the calcium carbonate caco3 organic carbon coorg trace element and rare earth element ree composition of surface sediments collected from a transect on the central western continental shelf and slope of india in the eastern arabian sea the transect samples across the oxygen minimum zone omz allows us to compare the relative abundances of trace elements and rees in the sediments beneath and beyond the omz shale normalized ree patterns lan ybn ratios and eu eu anamolies indicate that the sediments in the study area are either derived from the adjoining archaean land masses or from distal indus source sediment deposited in the omz have high u values from 3 6 to 8 1 ppm with their uexcess of that can be supplied by continental particles values ranging between 82 91 of the total u indicating that the u may be precipitated as u 4 in the reducing conditions of omz sediments deposited beneath the intense omz 0 2 ml l and away from the omz 1 2 ml l show slight negative ce anomalies with no significant differences between these two sets of sediments the ce ceshale values are poorly related to u and corg which are indicators of suboxic bottom waters normative calculations suggest that two sources namely terrestrial and seawater terrestrial seawater contribute to the total cc anomaly of the sediments the cc anomaly values of the calculated seawater derived component are similar to the anomalies reported for other coastal waters and the oxygenated surface waters of the arabian sea and do not show any correspondence to the lowered redox state of the overlying water probably due to the redirection of dissolved ce into the oxic deeper water this data on recently deposited sediments from a known oxygen poor environment suggest that the ce cesh in high sedimentation areas of continental margin environments may not be a good paleoredox proxy u th ratios above 1 25 noticed in omz are in accordance with the earlier usage of this ratio for identifying reducing environment of ancient sediments

rare earth element fractionation and concentration variations along a groundwater flow path within a shallow basin fill aquifer southern nevada usa abstract rare earth element ree concentrations were measured in 5 well water samples and 3 springs located along a groundwater flow path in a shallow tuffaceous alluvial aquifer from southern nevada usa the ree concentrations in these groundwaters decrease in the direction of groundwater flow a previous investigation demonstrated that ree solid liquid phase partitioning coefficients i e kd s for groundwaters from tuffaceous alluvial aquifers in southern nevada are relatively high mean kd 102 6 our groundwater ree data in conjunction with these kd s support strong sorption of aqueous rees to aquifer surface sites as the primary removal mechanism of rees from these groundwaters in addition relatively high aqueous ree concentrations occur at distinct locations along the groundwater flow path the elevated ree concentrations are explained by addition of deeper groundwaters influx of geothermal waters from a hot spring system differences in solution complexation and or mixtures of regional and local recharge sources solution complexation modelling of rees in the groundwaters indicate that carbonate complexes account for more than 99 of each rees in solution moreover groundwater yb nd ratios a measure of ree fractionation are associated with alkalinity hco3 co32 r 0 71 the data and speciation model results indicate that ree fractionation i e the observed heavy ree hree enrichments compared to rock sources is controlled by formation of progressively stronger carbonate complexes in solution with increasing atomic number which inhibits hree sorption compared to light rees lree and a greater affinity for the lrees to sorb to surface sites in the local tuffaceous alluvial aquifers compared to the hrees

trace element geochemistry of altered volcanic ash layers tonsteins in late permian coal bearing formations of eastern yunnan and western guizhou provinces china trace element compositions were determined by instrumental neutron activation analysis inaa in 30 samples of synsedimentary volcanic ash derived tonsteins and detrital claystones from coal seams within the late permian coal bearing formation of eastern yunnan and western guizhou provinces china the characteristics of trace element geochemistry in the tonsteins can be distinguished from those of detrital claystones because of the former s unique volcanic ash origin the detrital claystones are characterized by their relatively high content of v ti sc cr co and ni relatively low content of th and u th u ratio and small negative eu anomaly eu eu 0 63 0 93 overall these trace element characteristics are consistent with a mafic source similar to the composition of basalt rocks in the erosional region on the western edge of the study area in contrast the tonsteins are low in v ti sc cr co and ni contents and have a high th u ratio with a distinct negative eu anomaly eu eu normally in the range of 0 2 0 4 consistent with a silicic magmatic source within the group of tonsteins those from the lower section p2 1 of the coal bearing formation are relatively high in ti zr hf nb ta and rare earth elements ree as compared to those from the middle and upper sections p2 2 3 in trace element discrimination diagrams scatter plots of hf ta ti ta ti v hf sc lu hf and lu th tonsteins from the p2 1 horizon always fall in isolated distribution areas separate from the tonsteins of the p2 2 3 horizon these results suggest that the source materials of tonsteins from the two separate horizons were probably derived from volcanic ash falls of two distinctly different natures based on a comparison of the concentrations and assemblages of trace elements between various magmatic rocks the source materials of tonsteins from p2 1 horizon were mostly composed of calc alkalic silica poor volcanic ash similar to rhyodacitic magma whereas those from p2 2 3 were apparently more siliceous and k rich rhyolitic magma thus tonsteins from the two different horizons are characterized by unique geochemical properties which remain constant over a wide lateral extent integration of trace elemental compositions with mineralogical and textural observations makes possible the establishment of tonstein stratigraphy thus facilitating more precise and reliable coal seam correlations

trace element abundances in major minerals of late permian coals from southwestern guizhou province china abstract fourteen samples of minerals were separated by handpicking from late permian coals in southwestern guizhou province china these 14 minerals were nodular pyrite massive recrystallized pyrite pyrite deposited from low temperature hydrothermal fluid and from ground water clay minerals and calcite deposited from low temperature hydrothermal fluid and from ground water the mineralogy elemental composition and distribution of 33 elements in these samples were studied by optical microscopy scanning electron microscope equipped with energy dispersive x ray spectrometer sem edx x ray diffraction xrd cold vapor atomic absorption spectrometry cv aas atomic fluorescence spectrometry afs inductively coupled plasma mass spectrometry icp ms and ion selective electrode ise the results show that various minerals in coal contain variable amounts of trace elements clay minerals have high concentrations of ba be cs f ga nb rb th u and zr quartz has little contribution to the concentration of trace elements in bulk coal arsenic mn and sr are in high concentrations in calcite pyrite has high concentrations of as cd hg mo sb se tl and zn different genetic types of calcite in coal can accumulate different trace elements for example ba co cr hg ni rb sn sr and zn are in higher concentrations in calcite deposited from low temperature hydrothermal fluid than in that deposited from ground water furthermore the concentrations of some trace elements are quite variable in pyrite different genetic types of pyrites py a b c d have different concentrations of trace elements and the concentrations of trace elements are also different in pyrite of low temperature hydrothermal origin collected from different locations the study shows that elemental concentration is rather uniform in a pyrite vein there are many micron and submicron mosaic pyrites in a pyrite vein which is enriched in some trace elements such as as and mo the content of trace element in pyrite vein depends upon the content of mosaic pyrite and of trace elements in it many environmentally sensitive trace elements are mainly contained in the minerals in coal and hence the physical coal cleaning techniques can remove minerals from coal and decrease the emissions of potentially hazardous trace elements

lanthanide yttrium and zirconium anomalies in the fire clay coal bed eastern kentucky abstract the fire clay coal bed in the central appalachian basin region contains a laterally persistent tonstein that is found in the coal throughout most of its areal extent the tonstein contains an array of minerals including sanidine quartz anatase and euhedral zircon that constitutes strong evidence for a volcanic origin of the parting for this study five samples of the tonstein and four sets of coal samples underlying the tonstein were collected from five sites in eastern kentucky inductively coupled plasma mass spectroscopy icp ms analysis of the tonstein and underlying coal collected from four sites in eastern kentucky show that although zr concentrations are high in the tonstein 570 1820 ppm on a coal ash basis cab they are highest in the coal directly underlying the tonstein 2870 4540 ppm cab a similar enrichment pattern is observed in the concentration of y plus the sum of the rare earth elements y ree total y ree concentrations in the five tonstein samples range from 511 to 565 ppm cab however y ree contents are highest in the coals directly underlying the tonsteins values range from 1965 to 4198 ppm cab scanning electron microscopy of samples from coal which directly underlies two of the tonstein samples show that ree rich phosphate tentatively identified as monazite commonly infills cracks in clays and cells in clarain and vitrain zircon is rare and commonly subhedral on the basis of coal chemistry and grain morphology we suggest that volcanic components in the tonstein were leached by ground water the leachate rich in y and ree precipitated as authigenic mineral phases in the underlying coal

rare earth elements and yttrium in lithotypes of bulgarian coals abstract rare earth element and yttrium abundances in vitrain xylain liptain fusain and whole coal samples from bulgarian coal deposits have been studied vitrain xylain and liptain are depleted while fusain is enriched in ree and y as compared to the whole coal samples from which they were selected chondrite normalized patterns show relative enrichment of light lree against heavy hree rare earth elements negative eu anomaly and positive lu anomaly the shale normalized patterns of the lithotypes reveal an increase from lree to hree while those of the whole coal samples and mineral interlayers are less fractionated the petrographic composition of the coals is of secondary importance for the concentration of the ree and y the main factors are the source area and the input of dissolved ree and y into the coal depositional sites

the influence of depositional environments on coal petrographic composition of the lower kittaning seam western pennsylvania abstract lateral variations in maceral composition of the lower kittanning seam can be explained in terms of differential preservation of plant materials which is influenced by the ph eh of water within the peat swamp and by the rate of subsidence within the central part of the basin high telocollinite contents are observed this type of vitrinite represents large well preserved pieces of woody tissue whose preservation was favored by rapid burial towards the margins of the basin high desmocollinite contents are seen slower burial combined with the influx of neutral oxygenated fresh water permitted decomposition of the precursor materials producing this highly degraded type of vitrinite vertical variations in telocollinite and desmocollinite content can also be related to burial rates and ph eh conditions within the swamp throughout the basin high telocollinate contents observed in the lower part of the seam resulted from rapid burial under relatively low ph conditions continued high rates of subsidence led to an influx of neutral ph oxidizing waters associated with the encroaching marine environment under these new conditions more degradation of plant tissues occurred producing the high desmocollinite contents observed in the upper part of the seam this effect was most pronounced in the center of the basin an alternative explanation would be a change in vegetation type in response to the changing conditions the high desmocollinite content would then reflect a shift to a community dominated by smaller possibly herbaceous plants in addition to a change in vitrinite type towards the top of the seam a decrease in total vitrinite content and increases in total liptinite and inertinite contents are observed the increase in liptinite content is due to either 1 the higher resistance to decomposition of liptinite precursor materials when compared to vitrinite precursors in the more neutral conditions or 2 a change from a dominantly arborescent vegetation to a more herbaceous one the increase in inertinite results from an increase in transported material inertodetrinite and or an increase in the formation of inertinite macerals such as degrado fusinite possibly in response to the encroaching marine conditions an additional control on maceral composition is the level of metamorphism of the coal total liptinite content decreases towards the southeast in this area the coal has attained a sufficiently high rank that the reflectance of liptinite macerals approaches that of vitrinite thus making their identification difficult

paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks climate is a primary control on sediment flux from continental sources into sedimentary systems in warm climates siliciclastic input is greatest under highly seasonal rainfall nonseasonal conditions favor formation of end member chemical rocks perennially wet climates are conducive to coal formation whereas dry climates produce carbonates and or evaporites stratigraphic repetition of siliciclastic and chemical rocks therefore appears to be related to paleoclimate cycles as well as to transgressive regressive events and tectonics

palynologic petrographic and geochemical characteristics of the manchester coal bed in eastern kentucky the manchester coal bed in eastern kentucky is the stratigraphically lowest coal in kentucky that is both laterally continuous and of consistent mineable thickness the manchester coal bed occurs in the lower part of the breathitt formation in an interval between the underlying corbin sandstone and the overlying betsie shale both of which are also aerially widespread units the manchester is early middle pennsylvanian in age and is equivalent with the middle morrowan of the eastern interior basin and the late westphalian a of western europe increment samples were collected from the western and eastern outcrop and mining areas of the eastern kentucky coal field and were analyzed palynologically petrographically and geochemically to compare and contrast the two areas in the western part of the eastern kentucky coal field the manchester coal bed is uniform in occurrence and composition the bed is consistently 0 61 0 92 m 2 3 ft thick and generally is devoid of inorganic partings palynologically the coal in this area is largely dominated by lycospora the dispersed spore of many of the large lycopsid trees e g lepidodendron and lepidophloios and to a lesser extent granasporites medius representing diaphorodendron and synchysidendron petrographically the coal contains high percentages of vitrinite macerals and correspondingly low percentages of liptinite and inertinite macerals most of the increments from this area studied are generally low in ash yield 5 and sulfur content 10 and occasionally sulfur 1 in the eastern part of the coal field the manchester coal bed is typically thicker 3 ft 1 m but usually occurs as a coal zone with intercalated coal beds and clastic units palynologically the coal in this area contains increased percentages of small lycopsid small seed ferns calamites and cordaites petrographically the coal is higher overall in liptinite and inertinite macerals ash yields in the eastern sample area are generally low 10 an exception being some high ash durain bands overall sulfur contents also are low typically 1 the western samples are interpreted as having formed in a well protected generally flooded mire a consistent water cover would provide a favorable environment for arboreous lycopsid growth and proliferation and also inhibit oxidation of the peat surface thus promoting the formation of a high vitrinite content coal the eastern samples are also interpreted as having formed in a mire that was well protected most of the time giving rise to thick sequences of low ash low sulfur coal intermittent inundation by extra swamp waters carrying sediment in this area resulted in the development of a multiple coal zone i e several peat forming events with intervening clastic deposition in contrast to a single peat forming event in the western area surficial peat exposure was more frequent in the eastern area which allowed for increased microbial degradation of the peat and subsequent formation of inertinite macerals upon conversion to bituminous coal this condition might also accelerate charring of the peat surface by wildfire