classification of huminite iccp system 1994 abstract in the new classification iccp system 1994 the maceral group huminite has been revised from the previous classification iccp 1971 int handbook coal petr suppl to 2nd ed to accommodate the nomenclature to changes in the other maceral groups especially the changes in the vitrinite classification iccp 1998 the new vitrinite classification iccp system 1994 fuel 77 349 358 the vitrinite and huminite systems have been correlated so that down to the level of sub maceral groups the two systems can be used in parallel at the level of macerals and for finer classifications the analyst now has according to the nature of the coal and the purpose of the analysis a choice of using either of the two classification systems for huminite and vitrinite this is in accordance with the new iso coal classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals

crustal attenuation in the southern andean retroarc 38 39 30 s determined from tectonic and gravimetric studies the lonco luan asthenospheric anomaly abstract the western retroarc of the southern andes between 38 and 40 s is formed by a nnw elongated ridge not associated with stacked thrust sheets on the contrary during the last 4 3 ma this ridge was affected by extensional deformation regional uplift and related folding on a very broad scale receiver function analysis shows that the drainage divide area and adjacent retroarc lie over an attenuated crust expected crustal thickness at these latitudes is around 38 km whereas in this part of the retroarc the thickness is less than 32 km the causes for such attenuation have been linked to a moderate steepening of the subducted nazca plate beneath the south american plate which is suggested by a westward shift and narrowing of the magmatic arc during the last 4 to 5 ma gravimetric studies show that the upper plate did not react homogeneously to slab steepening but ancient sutures and lithospheric discontinuities deeply buried under mesozoic to cenozoic sequences in the retroarc were locally reactivated these processes resulted in an asthenospheric anomaly that correlates at the surface with the area of pliocene to quaternary doming widespread extension and three radial troughs two of the troughs have accommodated substantial amounts of extension but the third was probably aborted at an early stage moreover the presence of an anomalous concentration of calderas and large volcanic centers over the proposed asthenospheric anomaly and their age distribution may indicate minor migration of the asthenospheric anomaly between 4 and 2 ma through the western south american plate

mineralogy and petrography of the two lower eocene lacustrine coals sorgun and suluova turkey abstract coal reserves of lower eocene age are limited in turkey and the most important are situated in the sorgun and suluova basins a thick and laterally extensive coal seam occurs at the base of the celtek formation in the two basins the celtek formation was developed in a fluvial lacustrine facies and was unconformably overlain by transgressive units of middle upper eocene age the coal samples were studied mineralogically and petrographically and to define fluorescence emission spectra of sporinite and cutinite a total of 75 coal samples collected from the two basins are characterized on an air dried basis by relatively low moisture contents 0 69 9 31 wt av 3 90 wt a broad range of ash yields 2 4 67 8 wt av 19 9 wt total sulphur contents 0 55 7 60 wt av 2 15 wt and calorific values 1689 7480 kcal kg av 5458 kcal kg minerals of the coals from the two basins determined on an air dried basis by x ray diffraction method are mainly kaolinite quartz and pyrite kaolinite and pyrite contents of the sorgun coals are higher and quartz contents are lower than those of the suluova coals in addition a few samples in the sorgun coals contain epigenetic calcite whereas some samples in the suluova coals contain syngenetic siderite calcite and dolomite the coals in general are characterized by high contents of macerals of the huminite group av 69 0 vol and contain liptinite av 4 9 vol inertinite av 0 8 vol and mineral matter av 25 3 vol on the tpi and gi diagram the coals plot in the limno telmatic and telmatic areas in which the sorgun and suluova peats accumulated between the high and low water tables fluorescence emission spectra of sporinite and cutinite macerals are in general similar in the coals of both basins but the spectral maxima of sporinites and cutinites are between 594 658 nm and 592 671 nm respectively the values for the sporinites indicate a relatively broad range of coal rank however the range of values of the mean random ulminite mainly eu ulminite a reflectances 0 46 0 60 rr av 0 53 rr the proximate and ultimate analyses imply that the rank is a subbituminous a coal transitional to high volatile c bituminous coal according to the astm classification

contractional tectonics and magma paths in volcanoes abstract this study aims to contribute a possible explanation for magma migration within volcanoes located in contractional tectonic settings based on field data and physically scaled experiments the data demonstrate the occurrence of large stratovolcanoes in areas of coeval reverse faulting in spite of the widely accepted idea that volcanism can develop only in extensional transcurrent tectonic settings the experiments simulate the propagation of deformation from substrate reverse faults with different attitudes and locations into volcanoes the substrate fault splits into two main shear zones within the volcano a shallow dipping one with reverse motion propagates towards the lower volcano flank and a steeper dipping one with normal motion propagates upwards in plan view the reverse fault zone is arcuate and convex outwards whereas the normal fault zone is rectilinear structural field surveys at volcanoes located in contractional settings show similar features the plio quaternary trohunco and los cardos centinela volcanic complexes argentina lie above plio quaternary reverse faults the late pleistocene holocene el reventador volcano ecuador is also located in a coeval contractional tectonic belt these volcanoes show curvilinear reverse faults along one flank and rectilinear extensional fracture zones across the crater area consistent with the experiments these data consistently suggest that magma migrates along the substrate reverse fault and is channelled along the normal fault zone across the volcano

climate signals in sediment mineralogy of lake baikal and lake hovsgol during the lgm holocene transition and the 1 ma carbonate record from the hdp 04 drill core abstract modeling the bulk sediment xrd patterns allows insight into the environmental and depositional histories of two neighboring rift lake basins within the baikal watershed parallel 14c dated lgm holocene records in lakes baikal and hovsgol are used to discuss the mineralogical signatures of regional climate change in both basins it is possible to distinguish glacial and interglacial mineral associations clay minerals comprise in excess of 50 of layered silicates in bulk sediment the abundance of smectite expandable layers in mixed layer illite smectites and the total illite abundance are the main paleoclimatic indices in the clay mineral assemblage both indices exhibit coherent responses to the bolling allerod and the younger dryas the smectite layer index is not equivalent to the abundance of illite smectite because illite smectite tends to transform into illite repeated wetting drying cycles in soils and high abundance of expandable layers in illite smectites 42 favor the process of illitization this relationship is clearly shown in both baikal and hovsgol records for the first time the opposite late holocene trends in illite abundance in lake baikal and lake hovsgol records suggest that a sensitive optimal regime may exist for illite formation in the baikal watershed with regard to warmth and effective moisture the lake hovsgol sediments of the last glacial contain carbonates suggesting a positive trend in the lake s water budget a progressive change towards lower mg content in carbonates indicates lowering mineralization of lake waters this trend is consistent with the lithologic evidence for lake level rise in the hovsgol basin the pattern of mineralogical changes during the past 20 ka is used to interpret bulk sediment and carbonate mineralogy of the long 81 m lake hovsgol drill core hdp 04 with a basal age of 1 ma the interglacial type silicate mineral associations are confined to several thin intervals most of the sediment record is calcareous carbonates are represented by six main mineral phases calcite low mg calcite intermediate high mg calcite dolomite excess ca dolomite and metastable monohydrocalcite these mineral phases tend to form stratigraphic successions indicative of progressive changes in lake water chemistry five sediment layers with abundant mg calcites in the hdp 04 section suggest deposition in a low standing lake with high mineralization salinity and high mg ca ratios of lake waters lake hovsgol sediments contain the oldest known monohydrocalcite found tens of meters below lake bottom in sediments as old as 800 ka this unusual find is likely due to the conditions favorable to preservation of this metastable carbonate

rapid changes in magma storage beneath the klyuchevskoy group of volcanoes inferred from time dependent seismic tomography abstract we present the results of time dependent local earthquake tomography for the kluchevskoy group of volcanoes in kamchatka russia we consider the time period from 1999 to 2009 which covers several stages of activity of kluchevskoy and bezymianny volcanoes the results are supported by synthetic tests that recover a common 3d model based on data corresponding to different time windows throughout the period we observe a robust feature below 25 km depth with anomalously high v p v s values up to 2 2 we interpret this feature as a channel bringing deep mantle materials with high fluid and melt content to the bottom of the crust this mantle channel directly or indirectly determines the activity of all volcanoes of the kluchevskoy group in the crust we model complex structure that varies over time during the pre eruptive period we detected two levels of potential magma storage one in the middle crust at 10 12 km depth and one close to the surface just below kluchevskoy volcano in 2005 a year of powerful eruptions of kluchevskoy and besymiyanny volcanoes we observe a general increase in v p v s throughout the crust in the relaxation period following the eruption the v p v s values are generally low and no strong anomalous zones in the crust are observed we propose that very rapid variations in v p v s are most likely due to abrupt changes in the stress and deformation states which cause fracturing and the active transport of fluids these fluids drive more fracturing in a positive feedback system that ultimately leads to eruption we envision the magma reservoirs beneath the kluchevskoy group as sponge structured volumes that may quickly change the content of the molten phases as fluids pulse rapidly through the system

buoyancy driven fracture ascent experiments in layered gelatine laboratory experiments on air filled fracture propagation in solidified homogeneous and layered gelatine have been carried out providing an analogue model for magma filled dikes ascending in the crust the effects of layering on fracture velocity and shape have been analyzed in detail the free surface is found to accelerate approaching fractures layering accelerates or decelerates fractures approaching discontinuities of the elastic parameters depending on the value of the rigidity contrast the shape of fractures are strongly influenced as they pass from one layer to another the observed cross sectional shape when crossing a layer interface and the acceleration with decreasing rigidity can be explained with theoretical models our experiments also reproduce the arrest of fractures in proximity of joints and the formation of sills in the layer below the interface these findings could help in the interpretation of accelerated seismicity and deformation rates observed in volcanic areas

climate and vegetation changes around lake baikal during the last 350 000 years abstract we conducted particle size and pollen analyses on two cores extracted from lake baikal to investigate the response of vegetation to climate change and to assess the differences in vegetation changes between the northern and southern regions of lake baikal over the last 350 kyr vegetation changes in the lake baikal region corresponded well to the fluctuations in median particle size which are indicators of the climate changes in this region forest which was mainly composed of pinus and picea spread widely during the interglacials interstadials of mis 9 7 5 and 1 and open forest or desert covered most areas during the glacial stadial substages however the responses of vegetation to climate changes differed between the northern and southern regions generally vegetation expansion was restricted around the northern region during the interglacial substages equivalent to mis 9 3 7 5 and 5 5 forest spread widely around both the northern and southern regions however sparsely vegetated poor desert open forest covered the northern region during mis 5 3 and 5 1 while forest extended around the southern region in these substages moreover during glacial periods open forest composed mainly of artemisia chenopodiaceae amarantaceae betula and alnus covered the southern region while poor desert open forest covered the northern region these different vegetation responses are considered to have been caused by the geographical characteristics of the regions i e the mountains around the northern region and the plains around the selenga river in the southern region

the relationship between coal petrography and depositional environments from selected coal basins in canada abstract this paper reviews current research in canada relating to the sedimentology of coal bearing sequences and the petrographic character of contained seams from selected intermontane and foreland basin settings the intermontane cumberland and stellarton basins of nova scotia contain westphalian coal bearing strata of different character coal seams that formed in fluvial dominated depositional environments of the springhill coalfield cumberland basin commonly brighten upward and laterally display distinct areal zones a piedmont zone formed by interfingering of mire and distal fan sheetflow deposits an inner mire zone largely devoid of partings and a riverine zone with large scale seam splits about multistorey sandstone bodies maceral based groundwater influence and vegetation indices combined with miospore analyses indicate that the peat precursors of the no 3 seam of the inner mire zone accumulated from a groundwater influenced rheotrophic to mesotrophic forest mire swamp fen both the gelification of lignin derived maceral precursors and the domination of mire vegetation by lycopsid trees reflect this groundwater influence coal that formed from the frequently flooded paleomires of the stellarton basin is generally dull microbanded and mineral rich the location of mires within the basin was largely determined by basin subsidence rates when subsidence rates were high mires developed around the margin of a central basin lake coal seams that formed from these mires e g mcleod seam thicken toward basin margins and grade into sapropelic shale near the basin centre petrographic analyses of the mcleod seam suggest development from limnic to wet forest swamp conditions and a return to a limnic environment at the top of the seam thick coal e g foord seam developed near the basin centre during periods of lower subsidence rates and grades into red beds and paleosols toward the basin margin the foord seam of the basin centre is characterized by low mineral matter contents and a high proportion of degraded vitrinite macerals in the central parts of the seam interpreted to reflect prolonged peat accumulation with very limited clastic input the top and the base of the seam in contrast were subjected to significant clastic input as indicated by microbanding associated with significant amounts of detrital minerals and macerals coal seams of the lower cretaceous gates formation in the western canada basin formed in depositional settings ranging from coastal swamps strandplains to the upper delta plain strandplain coal is characterized by great lateral continuity and substantial thickness whereas coal of the upper delta plain is thin and discontinous the strandplain coal is characterized by variable lithotype sequences oscillatory brightening up dulling up maceral based facies parameters indicate a wide range of mire facies for these lithotype successions open moor forest moor herbaceous and or shrubby marshes and slightly raised mires results from megafossil and phyteral analyses suggest that the coastal plain mires were dominated by taxodiaceous conifers whereas ferns angiosperms and herbaceous lycopods are thought to have occupied the more marshy and or marginal stream lake side environments

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

holocene sedimentary records from lake borsog eastern shore of lake khuvsgul mongolia and their paleoenvironmental implications abstract this paper presents new sedimentological geochronological and diatom data from a 13 m core of sediment from lake borsog a former bay of lake khuvsgul also known as hovsgol and khubsugul in northwestern mongolia lake borsog was separated from khuvsgul during the early stages of a post glacial transgression and possesses a high resolution record of the holocene the data show three short events of higher rate sedimentation at 7 4 7 1 4 8 4 5 and 1 0 0 9 ka cal bp which are possibly related to lake level drops reduction of lake area progradation of the delta of the borsog river and higher erosion of the exposed lake shores the drops in lake level match the previously documented drops of the level of lake khuvsgul at ca 7 2 7 0 4 5 4 1 and 2 1 0 5 ka cal bp suggesting continued mutually related and climatically controlled evolution of both lakes after their separation

transient shallow reservoirs beneath small eruptive centres constraints from mg fe interdiffusion in olivine abstract small eruptive centres commonly have more primitive lavas than those associated with stratovolcanoes an observation that has been taken to indicate a short magma residence in the crust relative to those reservoirs below stratovolcanoes the caburgua cones of the andean southern volcanic zone from a basaltic small eruptive centre where this can be tested here we use melts simulations and the available thermobarometry data to determine the conditions of olivine crystal rim formation and the mg fe diffusion modelling to determine the magma residence times of those rims in the crust results yield timescales varying from a few days to dozens of days and if freezing is to be avoided can only be explained by some form of storage or slow transport through at least one shallow magma body the longest durations of magma residence seen in the olivine rim zones are up to 471 days these timescales are shorter than those estimated decadal from the nearby more differentiated and well established stratovolcano villarrica which has a dominantly basaltic andesite composition for caburgua cones we propose the existence of a transient reservoir in contrast to a long lived reservoir such as that inferred beneath the adjacent villarrica stratovolcano

magma ascent rates from amphibole breakdown an experimental study applied to the 1980 1986 mount st helens eruptions recent 1980 1986 mount st helens dacites contain the phenocryst assemblage plagioclase amphibole low ca pyroxene magnetite ilmenite and rare high ca pyroxene which indicates that they all originated from an 8 km deep reservoir at 900 20 c with xh2o 0 67 in fluid according to experimental data iron titanium oxide phenocryst compositions indicate that all post may 18 dacitic magmas erupted at 900 20 c except for the final lava extrusion in october 1986 the magma reservoir may have cooled to 866 c by october 1986 amphiboles in the post may 18 1980 magma contain one or more amphibole populations characterized by reaction rims of different thicknesses the development of the amphibole reaction rims in these rocks is a response to water loss from the coexisting melt during an approximately adiabatic ascent from a deep reservoir constant p and t and isothermal decompression experiments show that during a 900 c constant rate decompression from 8 km to the surface no reaction rim develops on amphibole in 4 days a 10 m rim develops in 10 days and a 35 m rim develops in 20 days these experimental data and histograms of rim widths in 1980 1986 mount st helens dacites show that post may 18 eruptions are composed in large part of magma represented by a population of thin rimmed amphiboles magma which ascended from the deep 8 km reservoir in 6 to 10 days the remainder of each sample consists of magma containing amphiboles with reaction rims ranging from 14 to 60 m magma which apparently spent from 8 to 25 days along the conduit margins before being mixed thoroughly millimeter scale into the erupting magma the mixing in a viscous slowly ascending dacite may be enhanced by its flow through partially crystallized magma emplaced earlier and by the evolution and loss of a large vesicle population the experimental calibration of amphibole reaction rim width versus decompression time yields average ascent velocities for post may 18 dacites of about 15 30 m h for magma represented by the thick rimmed amphiboles and from 35 to 50 m hr for magma represented by the thin rimmed crystals an ascent rate of 66 m h is indicated for the may 18 1980 eruption which contains amphiboles with no reaction rims the volume of endogenous dome growth which preceded extrusion of magma newly derived from the deep source region suggests that the effective conduit volume beneath mount st helens in 1981 1982 was equivalent to a cylinder 8 km long and 8 9 m in radius

contrasting nature of deformation along an intra arc shear zone the liquine ofqui fault zone southern chilean andes abstract the liquine ofquifault zone lofz cuts the patagonian batholith and the modern volcanic arc of southern chile for ca 1000 km the rock fabric along three transects of the lofz combined with new and published geochronological data suggest marked differences in the nature and timing of deformation along strike in the liquine transect 39 s a 1 km wide northeast striking subvertical mylonitic zone shows north plunging stretching lineations this mylonitic zone has been juxtaposed by high angle reverse faulting against a nearly undeformed miocene granitoid metamorphic assemblages and microstructures in the mylonites indicate greenschist facies conditions and sinistral reverse displacement deformation pre dates a 100 2 ma undeformed porphyritic dike hornblende 40ar 39ar mean age in the reloncavi transect 41 42 s deformation in cretaceous and miocene plutons is predominantly brittle kinematic analysis of two fault populations yields compressional and dextral strike slip stress regimes interpreted as late miocene in age in the hornopiren transect 42 43 s a 4 km wide mylonitic zone developed in plutons and wallrocks shows subhorizontal stretching lineations and dextral displacement a single fault population overprinting the mylonites supports a dextral strike slip stress regime available u pb k ar and 40ar 39ar dates on deformed cenozoic plutons and wallrock range from 9 to 13 ma on hornblende and from 6 to 3 ma on biotite microstructures and mineral assemblages indicate that the youngest ductile fabrics in the plutons formed at greenschist facies similar to the biotite ar closure temperature subparallel magmatic and solid state fabrics combined with geochronology suggest that dextral displacement was continuous during emplacement and cooling of the plutons dextral oblique subduction of the nazca plate beneath western south america has driven long term intra arc deformation at the southern andes plate boundary zone ridge collision in turn has favored dextral displacement at the leading edge of the continent since the pliocene

tectonic stress controls on ascent and emplacement of magmas abstract the tectonic stresses can significantly affect the propagation of a magma filled crack it has been pointed out that the rheological boundaries control the emplacement of magmas through the effect of stress however it has not been clarified how the role of rheological boundaries depends on the regional tectonic and thermal states we have evaluated the role of rheological boundaries under various tectonic and thermal conditions and found that the level of magma emplacement may jump according to the changes in the tectonic force or the surface heat flow the stress profiles were estimated by a simple model of lithospheric deformation we employed a three layer model of the lithosphere the upper crust the lower crust and the upper mantle have different rheological properties a constant horizontal force is applied to the lithosphere and the horizontal strain is assumed to be independent of depth when realistic tectonic forces 10 11 n m are applied the rheological boundaries mainly control the emplacement of magma the emplacement is expected at the moho the upper lower crust boundary and the brittle ductile boundary for lower tectonic forces 11 n m the tectonic stress no longer plays an important role in the emplacement of magmas when the tectonic stress controls the emplacement the roles of rheological boundaries strongly depend on the surface heat flow when the surface heat flow is relatively high 80 mw m 2 the stress in the mantle is quite low and the moho cannot trap ascending magmas for relatively low heat flow 2 on the other hand the moho acts as a magma trap and the upper lower crust boundary acts as a magma trap only when the magma supply rate is sufficiently high our results suggest that the emplacement depth can change responding to the change in the tectonic force and or that in the surface heat flow this may provide us a key to understand the relation between the evolution of a volcanic region and its tectonic and or thermal history

mineral matter major and trace element content of the afsin elbistan coals kahramanmaras turkey abstract the afsin elbistan coal basin is one of the most important coal deposits of turkey the mineral matter major and trace element concentrations of the afsin elbistan coals and their modes of occurrence are discussed in this study the coal seam is located within the upper miocene pliocene aged ahmetcik formation which is represented by fluvial lacustrine facies thickness of the coal zone is 80 m but it reaches 105 m in the kislakoy sector a total of 86 samples were taken from the kislakoy open pit mine and from the 14 boreholes drilled by the general directorate of mineral research and exploration mta for coal exploration the proximate xrd sem eds major and trace element analyses were conducted on the samples the studied coals are characterized by relatively high moisture ash total sulfur volatile matter contents and low gross calorific values the mineral matters of the afsin elbistan coal are represented by calcite quartz pyrite feldspar aragonite opal ct gypsum jarosite and clay minerals strontium rb sm zr hf nb mo u zn pb as mn co cr and ni concentrations detected by edp xrf are higher than the world brown coal values many of the trace elements showing positive correlations with ash content imply inorganic affinity the element concentrations of the coals are mainly related to the carbonate silicate sulfide phosphate ore minerals and fossil shells however some elements have also organic affinities

glacial meltwater in lake huron during early postglacial time as inferred from single valve analysis of oxygen isotopes in ostracodes abstract 18o measurements of benthic ostracodes are used to reconstruct the 18o history of lake huron and georgian bay water between 10 600 and 7600 14c yr b p this 18o record was calibrated using a comparison of the 18o values of modern ostracodes and lake huron water where a fractionation of 1 0358 was measured between the oxygen isotope ratios of the most isotopically positive ostracode candona subtriangulata and lake water the most positive shell 18o value was used because it is precipitated in the cold 0 to 2 c water common to both deep and shallow environments the 18o of lake huron water reflects a large glacial meltwater component for much of its history before 7600 14c yr b p times of low lake level correlate with the highest ratio of glacial meltwater to local precipitation in the basin most negative 18o values georgian bay water was more negative in 18o than lake huron water of the same age this reflects a higher proportion of glacial meltwater in georgian bay and its separation from lake huron during times of low lake level

the link between volcanism and tectonics in the southern volcanic zone of the chilean andes a review abstract the nature of the interplay between tectonics and volcanism is a major question in continental margin tectonics the southern andes volcanic zone svz located at the obliquely convergent nazca south america plate margin between 33 s and 46 s offers a unique opportunity to address this question because of along strike changes in crustal thickness tectonic style and well constrained long term and short term kinematic history the complex interaction between tectonic and magmatic processes is evidenced by both the architecture and geochemical signature of volcanic systems main first order factors accounting for the along strike variations in the nature and composition of volcanism are crustal thickness and the existence of a major intra arc fault system the liquine ofqui fault zone lofz second order factors include the local nature of the volcanic arc basement two main categories of volcano tectonic associations have been identified according to the spatial distribution and internal organization of individual volcanoes and clusters of volcanoes with respect to both the overall strike of the volcanic arc and the first and second order active inactive basement faults kinematically coupled associations those that are directly related to the current dextral transpressional tectonic regime include ne trending volcanic alignments of stratovolcanoes and or monogenetic cones kinematically uncoupled associations in which coupling with the current regime is not required include stratovolcanoes built on top of ancient reverse and strike slip faults of the volcanic arc basement and monogenetic cones lying along master faults of the lofz whereas mostly primitive magmas are found in the first category more evolved terms can occur genetically associated with the second category we propose a simplified three dimensional model for the magma plumbing system along and across the svz that integrates kinematically coupled and kinematically uncoupled volcano tectonic associations within the framework of first and second order geological and structural constraints

timescales of mixing and mobilisation in the bishop tuff magma body perspectives from diffusion chronometry we present two feldspar thermometry and diffusion chronometry from sanidine orthopyroxene and quartz from multiple samples of the bishop tuff california to constrain the temperature stratification within the pre eruptive magma body and the timescales of magma mixing prior to its evacuation two feldspar thermometry yields estimates that agree well with previous fe ti oxide thermometry and gives a 80 c temperature difference between the earlier and later erupted regions of the magma chamber using the thermometry results we model diffusion of ti in quartz and ba and sr in sanidine as well as fe mg interdiffusion in orthopyroxene to yield timescales for the formation of overgrowth rims on these crystal phases diffusion profiles of ti in quartz and fe mg in orthopyroxene both yield timescales of 150 years for the formation of overgrowth rims in contrast both ba and sr diffusion in sanidine yield nominal timescales 1 2 orders of magnitude longer than these two methods the main cause for this discrepancy is inferred to be an incorrect assumption for the initial profile shape for ba and sr diffusion modelling i e growth zoning exists utilising the divergent diffusion behaviour of ba and sr we place constraints on the initial width of the interface and can refine our initial conditions considerably bringing ba and sr data into alignment and yielding timescales closer to 500 years the majority of which are then within uncertainty of timescales modelled from ti diffusion in quartz care must be thus taken when using ba in sanidine geospeedometry in evolved magmatic systems where no other phases or elements are available for comparative diffusion profiling our diffusion modelling reveals piecemeal rejuvenation of the lower parts of the bishop tuff magma chamber at least 500 years prior to eruption timescales from our mineral profiling imply either that diffusion coefficients currently used are uncertain by 1 2 orders of magnitude or that the minerals concerned did not experience a common history despite being extracted from the same single pumice clasts introduction of the magma initiating crystallisation of the contrasting rims on sanidine quartz orthopyroxene and zircon was prolonged and may be a marker of other processes that initiated the bishop tuff eruption rather than the trigger itself

palaeoenvironment of seam i in the marathousa lignite mine megalopolis basin southern greece the present study aims to elucidate the depositional environment of seam i in the megalopolis basin southern greece using existing geological data supported by maceral and mineralogical analyses as well as by natural radioactivity determinations very high pyrite and uranium contents and a very low tissue preservation index usually suggest a marine influence during deposition in seam i however these features are most probably the result of a karstic aquifer supplying the palaeomire with sulphate rich neutral to weakly alkaline water the pyrite formation and the u precipitation are attributed to the anaerobic conditions which prevailed during peat accumulation the petrographic mineralogical and geochemical data of the studied profile point to several changes in the surface runoff and the supply of clastic material during deposition

the liquine ofqui fault zone a long lived intra arc fault system in southern chile abstract plate reconstructions for the cenozoic document relatively steady right oblique subduction of the farallon nazca plate beneath the chilean continental margin the kinematic signature recorded along the intra arc liquine ofqui fault zone lofz a major feature of the southern andes may help to understand the way in which the nazca south america slip vector has been partitioned into strain and displacement along and across the continental margin the lofz consists of two nne trending right stepping straight lineaments a strike slip duplex at the right step and curved features which splay off the straight lineaments toward the northwest the lofz runs mostly through heterogeneously deformed cenozoic plutonic rock of the north patagonian batholith and patchy metamorphic wall rock early cenozoic volcano sedimentary rocks and dyke swarms found in close spatial association with the strike slip duplex are believed to have developed in strike slip related basins quaternary volcanoes are aligned parallel to the lofz both ductile and brittle kinematic indicators within centimeter to meter wide high strain zones document late cenozoic dextral shear deformation contrasting left lateral deformation recorded on older and wider mylonitic zones suggests that the lofz may be a long lived shear zone that accommodated continental scale deformation arising from the farallon nazca south america plate convergence a block rotation pattern as indicated by paleomagnetic data is consistent with the geometry and cenozoic kinematics of the lofz

sedimentological and petrographical characteristics of cretaceous strandplain coals a model for coal accumulation from the north american western interior seaway abstract coal seams formed on many cretaceous wave dominated strandplain sediments in north america are characterized by great lateral continuity tens to hundreds of kilometres substantial thicknesses up to 12 m relatively low ash and sulphur contents the coals formed behind an active shoreline in areas undergoing subsidence due to shale compaction and dewatering the zone of peat accumulation was remote from the shoreline and storm tidal inundations and generally protected from fluvial flooding if the rate of subsidence was too great lakes formed and peat did not accumulate statistical evaluation of petrographic properties by correspondence analysis of the lower cretaceous coals show that the strandplain coals form distinctive petrographic groups that are characterized by relatively low vitrinite contents and high inertinite contents semifusinite and inertodetrinite dominate in the inertinite maceral group liptinite contents are negligible tissue preservation indices and gelification indices indicate for the strandplain coals a forest type paleodepositional environment in which a relatively low water table allowed the accumulation of oxidized and partly oxidized components fusinite and semifusinite significant amounts of detrital components such as inertodetrinite and vitrinite b are diagnostic that some transportation of the organic material took place prior to deposition comparison of coal facies and depositional environments from permian coals of australian show that the lower cretaceous strandplain coals have petrographic similarities to coals that were formed under regressive back barrier conditions in the permian due to differences in nomenclature previously interpreted regressive back barrier environments may be similar to the strandplain environments discussed here

basin wide sedimentation changes and deglacial lake level rise in the hovsgol basin nw mongolia abstract a study of 15 gravity cores reveals consistent patterns of lithologic change throughout the lake hovsgol basin sediments of the last glacial are composed of calcareous clayey silt with an admixture of coarse material from sand to gravel during the last deglaciation a basin wide deposition of finely laminated carbonate mud took place and was ultimately succeeded by the deposition of diatomaceous clayey ooze during the entire holocene interval diatom productivity in lake hovsgol during the early holocene was higher than today but declined by ca 6 6 cal ka bp sedimentation rate estimates for post glacial section range from 1 5 to over 6 7 cm ka for different parts of lake hovsgol rates appear to have decreased in the late holocene the last glacial maximum lgm corresponded to a dramatic low stand of lake hovsgol on the order of 100 m below today s level as reflected by littoral facies retrieved in cores from intermediate depths age dating of plant fragments in these sediments suggests that lake level started rising no later than 15 4 cal ka bp by the beginning of the holocene lake hovsgol evolved from a low level closed basin lake to an overflowing freshwater lake the observed dramatic lithologic change and evidence for lake level change suggest that lake hovsgol may in fact serve as a sensitive water gauge in continental interior asia and that the hovsgol sedimentary record preserves reliable proxies for past changes in effective moisture balance in the lake baikal catchment area

δ13c δ18c covariance as a paleohydrological indicator for closed basin lakes the relationship between 18o and 13c in a closed basin lake is a function of hydrological change vapor exchange lake productivity and total co2 or carbonate alkalinity concentration covariance of 18o and 13c usually occurs in lake sediments under the condition of hydrological closure for time periods of the order of 5000 yr or longer on shorter time scales however certain subtleties in the use of the 13c 18o covariance as a hydrology history indicator must be recognized the covariant trend may not be found in hyper alkaline lakes because of the insensitivity of 13c to lake volume changes for less alkaline closed basin lakes covariance of 13c 18o will result from relatively rapid increase or decrease of lake volume with the rapid decrease condition giving rise to heavy and narrow ranged isotopic values for both 13c and 18o due to the coupled evaporation productivity effect when the lake volume remains stable as is the case for an over flowing open lake poor 13c 18o covariance will ensue due to the effect of vapor exchange with the atmosphere we have used the measured 13c 18o covariance in carbonate sediments of mono lake california to deduce paleo hydrological and lake water alkalinity and salinity variations and found the results in consonance with holocene lake level history derived from the 18o and other information

fe mg interdiffusion rates in clinopyroxene experimental data and implications for fe mg exchange geothermometers chemical interdiffusion of fe mg along the c axis 001 in natural diopside crystals x di 0 93 was experimentally studied at ambient pressure at temperatures ranging from 800 to 1 200 c and oxygen fugacities from 10 11 to 10 17 bar diffusion couples were prepared by ablating an olivine x fo 0 3 target to deposit a thin film 20 100 nm onto a polished surface of a natural oriented diopside crystal using the pulsed laser deposition technique after diffusion anneals compositional depth profiles at the near surface region 400 nm were measured using rutherford backscattering spectroscopy in the experimental temperature and compositional range no strong dependence of d fe mg on composition of clinopyroxene fe mg ratio between di93 di65 or oxygen fugacity could be detected within the resolution of the study the lack of fo2 dependence may be related to the relatively high al content of the crystals used in this study diffusion coefficients d fe mg can be described by a single arrhenius relation with d text fe text mg 2 7 7 pm 4 2 7 times 10 7 text exp 3 20 7 pm 1 6 0 text kj text mol text rt m 2 text s d fe mg in clinopyroxene appears to be faster than diffusion involving ca species e g d ca mg while it is slower than d fe mg in other common mafic minerals spinel olivine garnet and orthopyroxene as a consequence diffusion in clinopyroxene may be the rate limiting process for the freezing of many geothermometers and compositional zoning in clinopyroxene may preserve records of a higher compared to that preserved in other coexisting mafic minerals temperature segment of the thermal history of a rock in the absence of pervasive recrystallization clinopyroxene grains will retain compositions from peak temperatures at their cores in most geological and planetary settings where peak temperatures did not exceed 1 100 c e g resetting may be expected in slowly cooled mantle rocks many plutonic mafic rocks or ultra high temperature metamorphic rocks

diatom record from lake hovsgol mongolia during the last 1 ma the results from the hdp 04 drill core abstract quantitative diatom abundance and species composition was studied in the longest 81 m lake hovsgol drill core hdp 04 lake hovsgol diatom biostratigraphy of the past 1 ma includes 14 local diatom assemblage zones ldaz planktonic diatom flora of lake hovsgol is dominated by members of stephanodiscus and cyclotella a large scale shift from stephanodiscus dominated to cyclotella dominated flora occurred in the mid brunhes chron significant morphological variability of cyclotella ocellata complex and cyclotella cf minuta as well as the presence of new extinct endemic taxa of genus stephanodiscus suggest long speciation and or adaptation history of diatom flora the recognition of taxa morphologically similar to the extinct endemic species of lake baikal suggests potential correlation ties between lake hovsgol and lake baikal diatom biostratigraphies around the mis 17 mis 25 and possibly mis 15 interglacial intervals narrow peaks of diatom abundance in the lake hovsgol sedimentary record are episodic and short lived these peaks may represent humid optima of past interglacials and or interstadials characterized by elevated surface runoff in the hovsgol basin and relative highstands of the lake

volcanism in a compressional andean setting a structural and geochronological study of tromen volcano neuquen province argentina we document evidence for growth of an active volcano in a compressional andean setting our data are surface structures and 39ar 40ar ages of volcanic products on tromen volcano tromen is an active back arc volcano in the andean foothills of neuquen province argentina its volcanic products are unconformable upon mesozoic strata of the neuquen basin the volcano straddles a n s trending pop up which formed during e w shortening the main underlying structures are eastward verging thrusts their traces curve around the eastern foot of the volcano minor folds and faults also occur in the volcanic cover of tromen as a result of e w shortening new 39ar 40ar ages for these volcanic rocks are younger than 2 27 0 10 ma and show that tromen has been active almost continuously from the late pliocene to the holocene we conclude that volcanism and thrusting have been coeval and that magma must have reached the surface in a tectonic setting of horizontal compression our results have wider implications for magmatic processes in such settings

orbital forcing of continental climate during the pleistocene a complete astronomically tuned climatic record from lake baikal se siberia abstract a new composite bdp 96 biogenic silica record over the entire pleistocene was generated by splicing bdp 96 1 and bdp 96 2 drill cores from lake baikal crosschecked against a similar record from a nearby bdp 98 drill core a new astronomically tuned age model is proposed based on correlating peak biogenic silica responses with the timing of september perihelia this target is derived from analysis of regional climate proxy responses during the holocene the last interglacial and around paleomagnetic reversals by resolving virtually every precessional cycle during the pleistocene the new age model represents a major improvement compared with previously reported lake baikal timescales the astronomically tuned ages of the pleistocene paleomagnetic reversals are consistent with published dates the minimal tuning approach we used precession only has also aligned high signal power in a narrow obliquity band confirming the strong presence of orbital forcing there are also strong ca 100 ka scale cycles but these are not aligned with the orbital eccentricity despite the location of lake baikal in a continental interior that is highly sensitive to insolation forcing the tuned biogenic silica record reveals a consistent phase difference of 32 ca 4 ka relative to insolation in the obliquity band an inherent lag embedded in a continental proxy record not driven by global ice volume is an intriguing finding another new observation is that long term changes in sedimentation rates in lake baikal appear to be related to the amplitude of orbital forcing both amplitudes and sedimentation rates undergo significant changes during mis 24 mis 19 interval corresponding to the middle pleistocene transition with potential for linking continental and marine climato stratigraphies the new baikal record serves a new benchmark correlation target in continental eurasia as an alternative to june 65 n insolation and odp correlated timescales

paleoenvironmental proxy records from lake hovsgol mongolia and a synthesis of holocene climate change in the lake baikal watershed abstract here we discuss paleoenvironmental evolution in the baikal region during the holocene using new records of aquatic diatom and terrestrial vegetation changes from hovsgol mongolia s largest and deepest lake we reconcile previous contradictory baikal timescales by constraining reservoir corrections of ams dates on bulk sedimentary organic carbon synthesis of the holocene records in the baikal watershed reveals a northward progression in landscape vegetation changes and an anti phase behavior of diatom and biogenic silica proxies in neighboring rift lakes in lake baikal these proxies appear to be responsive to annual temperature increases after 6 ka whereas in lake hovsgol they respond to higher precipitation runoff from 11 to 7 ka unlike around lake baikal warmer summers between 6 and 3 5 ka resulted in the decline not expansion of forest vegetation around lake hovsgol apparently as a result of higher soil temperatures and lower moisture availability the regional climatic proxy data are consistent with a series of 500 yr time slice holocene gcm simulations for continental eurasia our results allow reevaluation of the concepts of the holocene optimum and a maximum of the asian summer monsoon as applied to paleoclimate records from continental asia

petrographic characteristics and depositional environment of miocene can coals canakkale turkey abstract in this study petrographic examinations along with proximate calorific value ultimate sulphur form and xrd analyses were performed in order to determine the coal characteristics and the depositional environment of the miocene can coals seventy coal samples were taken from cores and open pit mines the investigated can coals are humic coals and classified as lignite to sub bituminous coal based on the random huminite reflectance 0 38 0 54 rr volatile matter 45 50 62 25 wt daf and calorific value 3419 6479 kcal kg maf the sulphur content of the can coals changes from 0 30 up to 12 23 wt and a broad range of ash contents was observed varying between 2 46 wt and 41 19 wt huminite is the most abundant maceral group 74 95 vol mmf consisting of mostly humocollinite gelinite which is followed by relatively low liptinite 2 18 vol mmf and inertinite content 2 13 vol mmf in general major mineral contents of coal samples are clay minerals quartz mica pyrite and feldspar the can etili lignite basin consists of mainly volcano clastics fluviatile and lacustrine clastic sediments and contains only one lignite seam with 17 m average thickness in order to assess the development of paleo mires coal facies diagrams were obtained from maceral composition according to the vegetation index vi and ground water index gwi the can coal accumulated in inundated marsh limnic and swamp environments under a rheotrophic hydrological regime in general the facies interpretations are in accordance with the observed sedimentalogical data

insolation regime in siberia as a major factor controlling diatom production in lake baikal during the past 800 000 years abstract a unique diatom biostratigraphy of the brunhes chron in lake baikal revealed by detailed studies of pelagic diatom paleo assemblages indicates that dramatic changes in insolation during the past 800 ka bp produced surprisingly rapid diatom speciation and extinctions the orbitally tuned age model allows the diatom assemblages to be compared with individual marine isotopic stages and substages during the brunhes most of the interglacial periods are characterized by explosive speciation and appearances of new pelagic planktonic diatom species in contrast most of the glacial periods are characterized by spectacular extinctions three broad periods characterized by different degrees of stability in the pelagic diatom assemblages are distinguished during the brunhes chron in the lake baikal sedimentary record mis 19 15e mis 15a 11 and mis 9 5 these periods are apparently associated with the long term changes in the amplitude of precessional insolation variations examination of individual interglacial periods further reveals the sensitivity of the baikal ecosystem to the regional energy balance virtually every precessional insolation peak during the early brunhes is characterized by a unique and peculiar paleo assemblage for the first time the siliceous microfossil record has demonstrated such a high degree of sensitivity to insolation forcing of regional climate despite the dramatic changes in the pelagic plankton driven by extreme climatic changes diatoms never went fully extinct during any glacial period although greatly or completely renewed during each subsequent interglacial the pelagic diatom assemblage still managed to return dominated by the new baikal endemic species the diatom assemblage observed in modern lake baikal despite being mostly endemic has formed during the past 50 100 ka and is therefore rather young these results demonstrate the remarkable capacity of this large freshwater system to sustain the dynamic stability on the large time scales

petrographical chemical and ft ir properties of a suberinitic coal from aydin germencik area western turkey abstract a suberinitic coal was discovered by coincidence during drilling for geothermal research in the germencik area drilling activity showed that the coal was 6 m in thickness on the upper part of the miocene aged basal conglomerate unit which is one of the important geothermal reservoir rocks in the germencik area petrographic ft ir xrd chemical and sem analyses were conducted to reveal the detailed properties of the suberinitic coal the coal is composed entirely of suberinite and phlobaphinites which are part of cork tissue these tissues also include features such as lamination and micro folding well preserved cork tissues and bark textures were observed abundantly in the coal samples jarosites gelified cork tissues are the most common alteration products observed in the coal samples ft ir analysis showed that suberinitic coal contains distinct peaks in the aliphatic c h stretching bands sem analysis reveals suberinitic textures and framboidal pyrite inclusions indicating metallic sulfur mineral sources hydrothermal fluids have important controls on the composition of the germencik area coals geothermal reservoir conditions affected coal rank and caused an increase in reflectance values as well as calorific values framboidal pyrites probably formed by means of geothermal water and associated mineralization in the region

uranium series chronology for sediments of lake hovsgol mongolia and the 1 ma records of uranium and thorium isotopes from the hdp 04 drill core abstract uranium and thorium isotopes in an 81 m long sediment core hdp 04 of lake hovsgol mongolia were measured to investigate their downcore distributions and to explore potential linkage to paleoenvironmental changes three dimensional isochron techniques using isotope ratio diagrams in 238u 234u 230th 232th system presented by ludwig and titterington were applied to age date the lake sediments at the depths of 11 42 14 71 and 14 83 m in the hdp 04 section the estimated ages of these horizons are 66 8 122 11 and 128 22 ka respectively the 238u concentration throughout the entire section fluctuated by a factor of 12 ranging from 19 9 to 232 1 mbq g with anomalously high 238u peak at 23 8 m in depth while the 232th concentration varied only by a factor of about two between 24 3 and 54 0 mbq g the discrimination of the bulk 238u into authigenic and terrigenous 238u fractions was attempted based on the measured 232th as a correction index for terrigenous materials in the upper 24 m corresponding to the last 250 ka the authigenic 238u was higher in interglacials and lower in glacials this depth profile of authigenic 238u contents was almost identical pattern with that found in a sediment core ver98 1 6 from the academician ridge lake baikal further this profile can be correlated well with that of photosynthetic pigment contents one of proxies of paleoproductivity suggesting that the variation of authigenic 238u contents were associated with the environmental change around lake hovsgol

reconstruction of deglaciation of northern mongolia for the last 330 ka bp inferred from ostracod stable isotope records from lake khubsugul we have compared 18o and 13c compositions of ostracod valves with elemental and grain size records of bottom sediments from the drill core kdp 01 northern mongolia nm formed for the last 330 ka bp the increase in the 18o values a high content of br and a low percentage of clay particles were found to positively correspond with high lake bio productivity and warm marine isotope stages mis 3 5 7 and 9 and visa versa during cold mis stages positive 13c values have been linked with high inflowing dissolved inorganic carbonates and forest steppe vegetation seems to be evidenced during cold mis stages mis 2 4 6 and 8 sharp depletions in the 18o values on 1 5 2 5 occurring during the ends of mis 6 and mis 4 could be induced by glacier meltwater discharge into lake khubsugul however shifts in the 18o values were not significant in mis 2 and mis 8 based on our assumption that the inflow rates of glacier meltwater were low due to the relatively small sizes of glaciers in the nm during these stages during mis 2 northern mongolian glaciers were the smallest in sizes due to high regional aridity the climate condition in mis 3 was not typically favorable for a warm mis stage while glaciers or snow patches formed in mis 4 most likely were still in the nm as a result isotopically depleted 18o meltwater was supplied into lake khubsugul at the period

an abrupt ecosystem change in lake beloye southern western siberia palaeoclimate versus local environment abstract sediment structure rock magnetic and bio geochemical records obtained from sapropel core samples in lake beloye southern western siberia indicate an abrupt ecosystem change at 3 4 calibrated ka bp the lake changed from eutrophic to oligotrophic its vegetation from carbon fixing macrophytic angiosperms to calcium fixing macrophytic algae and angiosperms and as a result the type of sedimentation shifted from peaty sapropel to carbonate rich sapropel those changes could be induced by climate which was warmer and wetter before 3 4 ka bp and cooler and drier after this nevertheless our data show that those ecosystem changes occurred when the lake became shallower to get about 1 m depth and started to freeze to the bottom in winter time the full freezing of the lake led to the deposition of carbonates which resulted in i death of carbon utilizing macrophytic angiosperms and ii winter precipitation of calcium carbonate in summer additional portions of ca 2 and hco 3 ions come into the lake from the surrounding caco 3 rich loess sediments with ground water the beloye lake thus represents an example of interrelated regional climatic and local ecological factors which combination resulted in the 3 4 cal ka bp dramatic change of its ecosystem

controls on conduit magma flow dynamics during lava dome building eruptions 1 lava dome eruptions commonly display fairly regular alternations between periods of high and low or no activity with timescales typically of weeks to years and sudden transitions between effusive and explosive activity we develop a transient model of the magma flow in a volcanic conduit from an open system magma chamber with continuous replenishment the model incorporates gas exsolution bubble growth gas escape through the magma and decompression induced crystallization and considers variations in magma temperature water content conduit diameter phenocryst size chamber volume and magma rheology calculations show the presence of periodic variations in discharge rate due to the transition from a stable regime when discharge rate is low and crystals grow efficiently leading to high magma viscosity to another stable state when discharge rate is high and crystallization is negligible the difference in discharge rates between these regimes can be several orders of magnitude periods are similar to the observed timescales and mainly depend on the chamber volume the system shows strongly nonlinear responses to the variation of governing parameters if magma has a bingham rheology pauses in discharge rate occur between peaks of discharge and the peaks are much higher than for the case of newtonian rheology large changes in discharge rate and eruptive behavior can occur as the consequence of small changes in magma temperature water content phenocryst size distribution or conduit diameter the system can fluctuate between low and high discharge rates with transitions to explosive activity

lake hovsgol basin as a new study site for long continental paleoclimate records in continental interior asia general context and current status abstract lacustrine sedimentary strata in the lake hovsgol rift basin nw mongolia preserved an important regional archive with new powerful proxies for climate change in continental interior asia two scientific drilling campaigns of the hovsgol drilling project hdp recovered the most complete and best resolved mid late pleistocene paleoclimate archive in mongolia with the basal age of ca 1 ma lake hovsgol drill core section complements those obtained previously in the neighboring lake baikal and contains regional paleoclimate proxy records on a timescale comparable to that of marine sedimentary records and the longest antarctic ice core record works in this volume discuss changes in lake chemistry biota and environment closely linked with drill core lithology and depositional trends apparent from sediment facies the current collection of works illustrates the potential of proxy signals in the hovsgol record and highlights new important constraints on their interpretation because of a nearly continuous record of endogenic carbonate accumulation in lake hovsgol a wealth of paleoclimate proxy data is preserved in carbonate mineralogy elemental geochemistry and stable isotope composition such a unique long record was not previously available in this part of the world the repetitive pattern of changes in the lake s water budget in response to the climatic cycles of the pleistocene is established and constrained by absolute dating and the robust paleomagnetic event reversal timescale the new proxy records from the hdp sediment sections are both relevant and timely contributions to the discussion of the nature of paleoclimate changes in continental interior asia during prior glacial and interglacial intervals of the pleistocene these records help establish the early timing of the post glacial changes in atmospheric circulation and effective moisture budget in the region and resolve the previously proposed scenarios of extreme precipitation gradients during glacial periods the key primary data presented in this volume make a compelling case for further in depth studies of the available records and for future deeper drilling into the early pleistocene and the pliocene strata in this basin

mineralogical and geochemical characterization of the saray and pinarhisar coals northwest thrace basin turkey abstract this study investigates the mineralogical and geochemical characteristics of coals from the saray and pinarhisar coalfields in the northwest thrace basin using optical microscopy scanning electron microscopy x ray diffraction and inductively coupled plasma mass spectrometry the saray and pinarhisar coals were deposited in a limnic environment the sulfur content of the coals ranges from 0 3 to 15 3 and high sulfur contents may originate from both seawater and volcanism pyritic and organic sulfur are the dominant sulfur forms 1 2 and 2 7 on average respectively the mineral matter of the coals consists mainly of pyrite barite gypsum muscovite and kaolinite with minor amounts of quartz butlerite tamarugite and rozenite the coals are enriched in trace elements including v 61 ppm on average co 5 85 ppm on average ni 79 ppm on average as 39 2 ppm on average th 3 6 ppm on average and u 6 7 ppm on average based on pearson correlation coefficients ti v cr fe co ni cu se rb au hg pb and th have mainly inorganic affinities r ash elements 0 5 in the pinarhisar coals fe as and au also have inorganic affinities r ash elements 0 5 in the saray coals the element contents and correlation coefficients indicate that the strandja massif the tethyan ophiolite belt and the oldest basement sediments were included in the sediment source region for both coalfields while the strandja massif was the prevailing sediment source region for pinarhisar coalfield

a short term establishment of forest fen habitat during pliocene lignite formation in the ptolemais basin nw macedonia greece the intermontane basin of ptolemais is part of a major tectonic trench located in nw greece and includes around 65 of greek coal reserves the upper xylite layer uxl is a distinct lignite layer being 3 6 m thick and outcropping in the upper part of the pliocene lignite bearing sequence at the notio field and tomeas eksi mines of ptolemais compared with the xylite rich lithotypes the matrix lithotypes within uxl contain more ash micropetrographic studies suggest that the upper xylite layer is rich in huminite 90 textinite dominates in the xylite rich lithotypes while attrinite dominates in the matrix lithotypes the liptinite content is 10 while inertinite rarely occurs palaeobotanical determination revealed that the xylite rich coal originated from coniferous vegetation specifically from glyptostrobus europaeus the occurrence of g europaeus as a coal forming element is significant because though this kind of vegetation was common in many greek coals of miocene age this is the first time it has been recorded from the pliocene this study suggests that the upper xylite layer is autochthonous according to coal facies diagrammes peat accumulated under pure telmatic conditions in a relatively wet forest fen both herbaceous and arboreal vegetation contributed to peat formation

pre eruptive reheating during magma mixing at quizapu volcano and the implications for the explosiveness of silicic arc volcanoes effusive explosive transitions are observed in volcanoes erupting water rich magmas that lack mineralogical evidence of degassing suggesting that gas loss occurred rapidly and ascent was fast despite the high viscosity of rhyodacitic to rhyolitic melts here we show that pre eruptive heating of water rich silicic magma by mixing with hot recharge in subvolcanic chambers controls the effusive explosive transition volcan quizapu chile emitted a 5 km3 mingled dacite andesite lava flow in a d 1846 1847 that was 130 c hotter than the 5 km3 of the same dacite that lead to a plinian eruption in a d 1932 we explain the suppression of explosive fragmentation in the 1846 1847 lavas by enhanced syneruptive magma degassing as a consequence of late reheating following mixing with andesite recharge higher magma temperatures led to the transitioning into effusive eruptive behavior by significantly accelerating volatile diffusion and lowering melt viscosity which facilitated bubble nucleation growth and coalescence while also inhibiting brittle fragmentation thus recharge by mafic magmas in subvolcanic magma chambers may reduce the risk of explosive eruptions in cases where heat can be efficiently transferred to cold volatile rich silicic magmas

coal geology and coal quality of the miocene mugla basin southwestern anatolia turkey abstract this work focuses on the relationship between the coal geology and coal quality of the miocene mugla basin southwestern anatolia turkey to this end detailed petrographical mineralogical and geochemical studies were performed on composite profile samples from the nine coal fields in the mugla basin alatepe bagyaka bayir cakiralan ekizkoy eskihisar husamlar sekkoy and tinaz coal fields the mugla lignite is a high ash from 16 to 56 and sulphur from 2 1 to 5 7 lignite which is petrographically characterised by a high huminite content mainly gelinite macerals the mineral matter of the studied lignite samples is made up mainly of clay minerals and quartz with the exception of the sekkoy and ekizkoy lignites in which calcite is the dominant mineral phase with minor amounts of quartz clay minerals pyrite and gypsum and traces of aragonite syngenetic opal is also frequently identified in these samples the differentiation of these two types of lignite with specific mineralogical patterns is attributed to the contemporaneous development of peatlands with a high detrital input dominated by the quartz and clay mineral setting and peatlands with low detrital supply and a dominant carbonate rich lacustrine environment the higher water table of the latter allowed the precipitation of micritic carbonates and the development of lakes with abundant mollusc fauna this differentiation is also evidenced by the geochemical data thus the sekkoy ekizkoy husamlar bayir and alatepe lignites are characterised by relatively low al and fe contents

volcanism in compressional tectonic settings is it possible 1 this study presents the first field evidence of emplacement of a huge stratovolcano within contractional tectonics in spite of the widely accepted idea that volcanism can develop only in extensional or transcurrent tectonic settings el reventador volcano ecuador started to grow 0 32 ma bp and is still active during pre el reventador times its substratum has been affected by n s to nne striking reverse faults during late pleistocene holocene some reverse faults with the same orientations were still active locally with a component of right lateral strike slip motions seismicity shows widespread events with intensity up to 6 9 mw and compression some of these faults cut the volcano creating differential uplift along n s to nne trending tectonic blocks hypocenter swarms and field data indicate east vergent basal thrusting under the volcano and n s trending fault propagation folds to the east a model for magma migration in this setting is proposed suggesting that similar cases of volcanism within a dominantly contractional tectonic regime may be more frequent than previously thought

response of phytoplankton productivity to climate change recorded by sedimentary photosynthetic pigments in lake hovsgol mongolia for the last 23 000 years abstract we analyzed photosynthetic pigments total organic carbon toc and total nitrogen tn in two radiocarbon dated sediment cores of lake hovsgol nw mongolia covering the period of the last glacial post glacial transition since 23 14c ka the sedimentary profiles of total chlorophyll a derivatives tchl a toc and tn reflect productivity increase during the last glacial post glacial transition between 15 and 10 14c ka in response to regional climate warming and enhanced precipitation correlation between tchl a and toc was high r 2 0 934 n 74 with a zero intercept of a regression line suggests that total organic carbon in lake hovsgol sediments is of autochthonous origin the depth profiles of toc tn ratio showed increases toward the core top in parallel with other paleoproductivity proxies serving as an indicator of climatic transition quite similar to lake baikal sedimentary record the primary reason for the shifts of this parameter is still not clear however chlorophyll b derivatives and some algal carotenoids such as lutein zeaxanthin diatoxanthin and canthxanthin were detected although in concentrations lower than that of tchl a these biomarkers indicate that green algae cyanobacteria and diatoms were present in phytoplankton during the post glacial period significantly pre dating the beginning of the holocene abrupt drops of biomarker profiles at ca 1 2 and 10 14c ka due to decreased productivity in the lake or enhanced degradation of the biomarkers likely record short term climatic events

plagioclase residence times at two island arc volcanoes kameni islands santorini and soufriere st vincent determined by sr diffusion systematics the diffusive relaxation of trace element profiles in plagioclase phenocrysts may provide important constraints on magma residence times in crustal magma chambers initial trace element profiles in plagioclase phenocrysts are governed by variations in the concentration of a trace element in the melt and by the plagioclase melt partition coefficient trace element diffusion will subsequently act to modify this initial profile and given enough time produce a profile that is in equilibrium with the anorthite variations within the crystal we argue that the trace element partition coefficient da b between two parts a and b of a plagioclase crystal of variable anorthite content is equal to the ratio of their crystal liquid partition coefficients and that the equilibrium profile of the crystal can be calculated the time required to establish diffusive equilibrium is dependent on the wavelength and amplitude of the initial trace element concentration range and on the diffusivity of the trace element in plagioclase strontium plagioclase melt partition coefficients and diffusivities are calculated for a range of magmatic temperatures and plagioclase compositions a one dimensional diffusion model is developed that describes the diffusive destruction of oscillatory trace element zoning with time and allows the calculation of upper limits for plagioclase crystal residence times in a magma reservoir the model is tested using major and trace element concentrations measured along crystal traverses of plagioclase phenocrysts from the kameni island dacites santorini and from the 1979 soufriere andesite st vincent three out of eight plagioclase phenocrysts have sr concentration profiles that are not in diffusive equilibrium for these the diffusion model is employed to calculate maximum crystal residence times from incomplete diffusive equilibration of trace element zoning in plagioclase maximum crystal residence times range from 100 to 450 years this is in good agreement with estimates from crystal size distribution and from ra th disequilibrium studies for the kameni islands for soufriere however such short residence times are incompatible with u th mineral errorchron data that suggest residence times of 40 ka in a thermally buffered magma reservoir to reconcile these apparently different ages we invoke a more complicated magmatic history for soufriere where an initially buffered magma reservoir is disturbed by magma mixing and suffers limited additional crystal fractionation prior to eruption

climate control of sulfate influx to lake hovsgol northwest mongolia during the last glacial postglacial transition constraints from sulfur geochemistry abstract changes in sulfur cycles in lake hovsgol northwest mongolia are discussed on the basis of total organic carbon toc total sulfur ts concentrations and stable sulfur isotope ratios 34 s in two sediment cores x104 and x106 covering the last glacial to the present correlation plots of toc and ts c s plots of the sediment cores indicate dissolved sulfate enrichment in sediment pore water and high sulfate reducing bacteria srb activity during the climate transition from the last glacial to postglacial period lg pg transition from ca 21 to 11 6 cal ka bp in addition positive shifts of 34 s values from 3 7 to 32 6 were observed during the lg pg transition these results suggest a large influx of 34 s rich dissolved sulfate into the lake during this period the 34 s rich dissolved sulfate may have accumulated on the shore wetlands and marshes of lake hovsgol during the last glacial period owing to the increase in atmospheric precipitation and lake level rise during the lg pg transition the 34 s rich dissolved sulfate may have been supplied from the shore to the lake increased sulfate influx during the lg pg transition has also been observed in a lake baikal sediment core our new sulfur geochemical data shows past environmental changes particularly moisture changes within continental asia during the climate transition

petrology palynology coal facies and depositional environments of an upper carboniferous coal seam minto coalfield new brunswick canada coal petrology and palynology of the minto coal seam enable depositional environments of the precursor mire to be established in terms of facies critical maceral ratios maceral assemblages and spore and pollen assemblages the overall petrographic composition indicates a vitrinite rich coal mean 67 followed by inertinite mean 27 and liptinite mean 7 pyrite is common to abundant maximum 15 lithotype logs demonstrate a dominance of dull lithotypes dull and banded dull petrographic composition at the lithotype and seam subsection level is highly variable vitrinite maceral assemblages are enriched in brighter lithotypes banded bright and bright whereas liptinite and inertinite maceral assemblages are enriched in dull and banded dull lithotypes the duller lithotypes are enriched by mineral matter based on spores the seam is assigned to the vestispora zone of atlantic canada with the basal torispora securis torispora laevigata sl zone of western europe and the lower torispora secur

characterization of turkish coals a nationwide perspective abstract the u s geological survey usgs and the turkish general directorate of mineral research and exploration maden tetkik ve arama genel mudurlugu mta are working together to provide a better understanding of the chemical properties of turkish coals from major turkish lignite producing areas the coals in turkey are generally low rank lignite or subbituminous formed in several different depositional environments at different geologic times and have differing chemical properties eocene coals are limited to northern turkey oligocene coals found in the thrace basins of northwestern turkey are intercalated with marine sediments miocene coals are generally located in western turkey the coal deposits which have limnic characteristics have relatively abundant reserves pliocene pleistocene coals are found in the eastern part of turkey most of these coals have low calorific values high moisture and high ash contents analysis of 143 coal channel samples most are lignite and subbituminous in rank but a few are bituminous and one is anthracitic in rank has been completed for up to 54 elements and other coal properties using a variety of analytical techniques including inductively coupled plasma emission and mass spectrometry instrumental neutron activation analysis and various single element techniques and astm standard procedures many of these coals have elemental concentrations similar to u s lignites found in the gulf coast and fort union regions however maximum or mean concentrations of b cr cs ni as br sb cs and u in turkey are higher than the corresponding maximum or mean values found in either the fort union or gulf coast regions

dynamic plumbing system beneath volcanoes revealed by kinetic modeling and the connection to monitoring data an example from mt etna abstract our ability to monitor volcanoes using seismic signals ground deformation gas fluxes or other ground and satellite based observations as well as our understanding of melt reservoirs that feed eruptions have evolved tremendously in recent years the complex plumbing systems that are thought to feed eruptions are however difficult to relate to the monitoring signals here we show that the record preserved in compositional zoning of erupted minerals may be used to reconstruct sections of the plumbing system kinetic modeling of such zoning can yield information on the residence time of magma in different segments of the plumbing systems this allows a more nuanced evaluation of the link between observed monitoring signals or eruption styles and the magmatic processes and movement of batches of melts at depth the approach is illustrated through a study of the compositional zoning recorded in olivine crystals from the 1991 1993 se flank eruption products of mt etna sicily the zoning patterns in crystals reveal that the plumbing system of the volcano consisted of at least three different magmatic environments between which magma was transported and mixed in the year or two preceding the start of eruption quantification of this history indicates that two main pathways of melt migration and three timescales dominated the dynamics of the system combination of this information with the timing of observation of various monitoring signals allows a reconstruction of the dynamic evolution of this section of the plumbing system during the early stages of the 1991 1993 eruption it is seen for example how the migration of melt through the same sections of the plumbing system can cause pre eruptive triggering enhance strombolian activity and through the ensuing eruption cleanse and flush the plumbing system different kinds of mixing occur simultaneously at different sections of the plumbing system on different timescales a few days up to two years

petrographic properties of major coal seams in turkey and their formation abstract most types of coal in turkey are generally low in rank lignite and subbituminous most of the coal was formed during the miocene eocene and pliocene ages there are only a few thin jurassic age coal occurrences in turkey pennsylvanian age bituminous coal is found on the black sea coast general implications of the petrographic properties of turkey s coal seams and coal deposits have not yet been taken into consideration comparatively or as a whole for this study about 190 channel samples were collected from different locales the composite profile samples of the seams were taken into considerations the content and depositional properties as well as some chemical and physical properties of the main coal seams are compared all coal samples tend to have similar coal petrographic properties and were deposited in intermontane lacustrine basins later they were affected by faulting and post depositional volcanic activity as a result there are variations in the properties and rank of the coal samples the most abundant coal maceral group is huminite and the most abundant maceral is gelinite the liptinite and inertinite contents of the coal are low and the maceral contents of the coals show great similarity the depositional environments of the all coals are lacustrine dominated

lake qinghai china closed basin like levels and the oxygen isotope record for ostracoda since the latest pleistocene abstract in 1985 a sino swiss limnogeological expedition to china s largest inland lake recovered seismic profiles and piston cores to help calibrate palaeoclimatic models of monsoon and insolation fluctuations over the northern tibet qinghai plateau since the last glacial maximum lake qinghai a perennial lake with an area of 4278 km2 1985 at 3194 m above sea level receives drainage from 30 000 km2 of catchment near the northwest corner of the plateau the 26 5 m deep terminal lake 1985 with brackish alkaline magnesium sulphate rich waters 14 g 1 1 tds has not overflowed since the last glacial but its levels have responded to climatic and hydrologic changes seismic reflection profiles for the sub bottom sediment structures revealed a complex topography with channels relict terraces tectonic tilting and deformation in deposits buried under a 4 6 m packet of mainly flat bedded sediments from which core samples were recovered the lowermost cored material 14 500 yr b p comprises mainly water lain loess deposited in a smaller flood plain lake of up a few metres depth under cold arid climatic conditions ams radiocarbon dating indicates average sedimentation rates for latest pleistocene and holocene deposits in central basin regions of 0 3 0 5 mm yr 1 the 18o values of fossil ostracod valves provide a record of changes in the isotopic chemistry of the lake waters that can be related to the precipitation evaporation budgets which have controlled the palaeo levels for lake qinghai the precipitation evaporation budget for the lake qinghai region is largely determined by the asian monsoon system the lake qinghai sediment record shows that there was no large influx of glacoer melt waters into the lake basin during the post glacial the regional climate remained arid until at least 12 500 yr b p when an incipient monsoon was possibly initiated river transported silts first reached the basin centre at 11 800 yr b p when the lake depth may have increased to 5 m possibly a monsoonal weakening for several centuries after 10 800 yr b p europe younger dryas caused a further period of aridity at 10 200 yr b p the basin began filling towards modern lake dimensions in response to a permanent strengthening of the asian monsoon substantial lake level rises probably characterised the periods 10 200 9800 9500 8500 8300 7200 yr b p and through perhaps a century at about 6800 yr b p decreasing levels probably characterised the intervening intervals short term lake level fluctuations through the mid holocene climatic optimum were minimal indicating a very stable climatic hydrologic regime an isotopic steady state for the lake waters since 3000 500 yr b p obscures the climatic hydrologic regime dependent 18o gradient but there is little stratigraphic evidence to suggest that the lake level has been significantly below its present level since that time three negative 18o excursions for the lake waters may correspond to known glacier advances on the plateau at 3000 2000 and 1500 yr b p during china s neoglacial

minerals in bituminous coals of the sydney basin australia and the illinois basin u s a although other forms of inorganic components may be significant in lower rank coals the mineral matter in most bituminous coals is dominated by silicates carbonates sulphides phosphates and other crystalline mineral groups these may be present in various forms including thin bands and laminae intimately associated with the organic matter as well as lenticles nodules crystal aggregates and cell infillings all of which indicate approximately contemporaneous formation with the peat bed other minerals however occur as veins or cleat and fracture fillings indicating precipitation after most of the compaction and presumably after most of the rank advance ome of the penecontemporaneous mineral matter is of detrital origin representing epiclastic or pyroclastic particles washed or blown into the peat swamp other mineral matter however including much of the pyrite quartz and siderite as well as abundant well crystallized kaolinite appears to have been formed by precipitation processes either within the swamp waters or in the pores of the peat deposit pyrite largely formed by bacterial reduction of dissolved sulphate ions seems to be related in abundance to marine transgressions which allowed permeation of sea water into the swamp and through the peat bed beneath siderite appears to form in the absence of sulphate rich sea water probably from co2 released by organic decay the clay fraction of the noncoal rocks in many coal bearing sequences is typically dominated by illite or interstratified clay minerals with kaolinite chlorite and possibly montmorillonite also present to a variable though typically minor extent although perhaps modified by chemical reactions or ion exchange mechanisms in the peat swamp these clay minerals may also be present in the coal as well especially near the base of top of the seam the kaolinite in the noncoal rocks is usually poorly crystallized and typically a minor constituent but well crystallized kaolinite is characteristically present and often the dominant component in the mineral fraction of bituminous coal beds as well as in some of the lutites including underclays intimately associated with the seams a progressive upward gradation to a particularly kaolinite dominated mineral assemblage occurs in some seams of the sydney basin australia this gradation is thought to be due to either increased blockage of detrital contaminants as the swamp developed or to in situ chemical or biological leaching of the mineral fraction and reconstitution of the residues in the upper parts of the peat bed superimposition of such cycles is also noted within the seam in some instances suggesting repetition of several phases of this type during major peat accumulations

structural controls of volcanism in transversal chains resheared faults and neotectonics in the cordon caulle puyehue area 40 5 s southern andes abstract the nature of the relationship between tectonics and volcanism in a specific area is the result of the interaction between the crustal structures of the basement and ongoing regional stress field in the southern andes different kinematic environments represented by two nearly orthogonal active fissure systems show apparently incompatible arrays of volcanic chains moreover a local quaternary compressive regime is inferred from basement faults however these mutually orthogonal chains which are also oblique to the volcanic front have contrasting magma evolution and eruptive styles that can be related with their tectonic setting whereas northeast trending monogenetic cones carran los venados can be interpreted as resulting from magma upwelling along regional tension cracks in a quaternary dextral transpressive compressive domain northwest striking fissure system cordon caulle volcanic complex can be the result of extensional fault reactivation and long magma residence in the upper crust different kinematic environments cause contrasting magma evolution and eruptive styles a two way coupling mechanism is suggested for to explain local depart of the regional stress field geometric array of extensional features and final magmatic evolution in these volcanic domains of the southern andes

interaction between forearc and oceanic plate at the south central chilean margin as seen in local seismic data we installed a dense amphibious temporary seismological network to study the seismicity and structure of the seismogenic zone in southern chile between 37 and 39 s the nucleation area of the great 1960 chile earthquake 213 local earthquakes with 14 754 onset times were used for a simultaneous inversion for the 1 d velocity model and precise earthquake locations relocated artificial shots suggest an accuracy of the earthquake hypocenter of about 1 km horizontally and 500 m vertically crustal events along trench parallel and transverse deep reaching faults reflect the interseismic transpressional deformation of the forearc crust due to the subduction of the nazca plate the transverse faults seems to accomplish differential lateral stresses between subduction zone segments many events situated in an internally structured planar seismicity patch at 20 to 40 km depth near the coast indicate a stress concentration at the plate s interface at 38 s which might in part be induced by the fragmented forearc structure

geological controls on the mineralogy and geochemistry of the beypazari lignite central anatolia turkey abstract the raw coal from the cayirhan mine beypazari basin turkey contains an average of 28 5 mineral matter consisting up to 80 zeolites the coal seam is split by a 1 m thick tuffaceous siltstone into the upper first tv and lower second tb seams which contain essentially different zeolites the first seam contains ca rich zeolites clinoptilolite heulandite whilst the second seam contains na rich zeolites analcime experimental work has shown that a na rich activation solution will produce na rich zeolites when the original volcanic glass is na rich but will produce ca rich zeolites when the volcanic material is ca rich it is thought that a na rich activation solution derived from contemporaneous volcanics in the beypazari basin reacted with volcanic tuffs of different chemical composition to produce the vertical variability in the mineral matter of the two seams trace element analyses of the raw coal showed that they are enriched in as b cr ni and zr when compared to world wide averages of coal they are also enriched in the major elements na and k these elements are probably also derived from a volcanic source barium and sr show a clear affinity for analcime whilst li cr ni cu zn co and ga show a clear affinity for clinoptilolite heulandite trace elements showing a positive correlation with the organic matter are mn b be ge y zr nb hf w and u manganese u th sc ge and hree heavy rare earth elements show correlations with phosphate trace elements showing correlation with both fe and s contents are co mo ta pb and iree intermediate rare earth elements arsenic and v seem to have mixed affinities with sulphides and zeolites and organic matter and zeolites respectively although a proportion of the as b and s are retained in the ash during coal combustion due to the sorption mechanism of cao derived from the clinoptilolite heulandite decomposition significant emissions of these elements may arise from the cayirhan thermal power station due to the anomalously high concentrations of these elements in the beypazari coal the high total alkali metal content of these coals exceeds the recommended maximum for steam coal but it is believed that sodium occurring in a mineralogical form such as analcime is not as likely to contribute to boiler fouling as organically associated sodium

paleoenvironmental changes in northern mongolia during the last deglaciation revealed by trace element records in ostracods from lake hovsgol ostracods possess bivalve carapaces composed of low mg calcite which can be preserved in a variety of sedimentary environments they are a useful paleoenvironmental indicator in particular for non marine environments although previous studies of lake baikal and lake hovsgol have provided some evidence of large scale paleoenvironmental changes in central asia during the late pleistocene trace element records in ostracods from these two lakes which may reveal the detailed limnological processes have not yet been reported in this study we analyzed stable isotopes and trace elements in ostracods in three gravity core sediments recovered from lake hovsgol northern mongolia to reconstruct the long term limnological histories of the lake radiocarbon dating results indicated that ostracod bearing core sediments were deposited from 14 5 to 21 5 ka which corresponds to the early stage of the last deglaciation including the last glacial maximum lgm the mg ca and sr ca ratios from two species of ostracods c lacustris and l inopinata ranged from 4 to 25 and 3 5 mmol mol respectively with distinct and consistent decreasing trends the changes in the mg ca and sr ca ratios indicate that the salinity of the lake water decreased substantially at the initial transition from the last glacial to the current interglacial period which was mainly due to the ice melting and introducing fresh water into the lake changes in the fe ca and u ca ratios were interpreted as water circulation changes in the bottom of the lake after the lgm the fe ca and u ca ratios gradually increased indicating that inflowing cold water induced stronger water circulation and subsequently a higher dissolved oxygen content in the bottom water of the lake the mn ca ratio had the opposite trend to the u ca and fe ca ratios which suggests that it was affected by the weathering intensity in the area around lake hovsgol the stable isotopic results for c lacustris support our paleoenvironmental interpretations in the region on the basis of trace elements as a result ostracod geochemical records from lake hovsgol northern mongolia provide new insights into paleoenvironmental changes in central asia during the onset of the last deglaciation

depositional environment of the late miocene hausruck lignite alpine foreland basin insights from petrography organic geochemistry and stable carbon isotopes abstract lignites and fossil wood from two boreholes in the late miocene hausruck district alpine foreland basin austria were investigated with respect to organic carbon and total sulfur contents ash yields maceral composition organic geochemistry and stable carbon isotope ratios the lignites from the two sampled profiles differ in sulfur contents and petrography based facies indicators gelification index gi tissue preservation index tpi the results point to drier and more acidic conditions in the part of the mire sampled at drill site lukasberg whereas the lignites from kalletsberg formed under near neutral conditions due to a raised ground water table the different depositional environments are supported by the paleogeographic positions of the boreholes borehole lukasberg is located within a paleo valley whereas borehole kalletsberg is located at the deeper part of a basin situated south and southwest of the hausruck area environmental changes with time within the mire are confirmed by the molecular composition of the soluble organic matter som differences in pristane phytane ratio isomerisation of hopanes at position 17 concentrations of hopanes and in the ratio of hopanes to hop 17 21 enes are related to the extent of gelification of plant tissue sulfur content and ph values caused by differences in ground water table the variable contents of individual terpenoid hydrocarbons derived from land plants indicate that angiosperms and conifers contribute to peat formation in the hausruck district in variable proportions overall angiosperm biomarkers slightly predominate the tissue preservation index tpi within the kalletsberg profile is probably governed by the proportion of decay resistant conifers as indicated by the correlation between tpi and biomarker composition of the coals correlations between 13 c values of the lignites between 24 9 and 27 4 and their non hopanoid terpenoid composition indicate the major influence of changes in peat forming vegetation on the carbon isotopic composition of the coals in the hausruck district carbon isotope data of macrofossils are consistent with their taxonomical classification as conifers 13 c between 22 7 and 25 1 and angiosperms 13 c between 25 5 and 26 6 respectively the 13 c data of the extracted cellulose reveal clear differences between fossil wood from gymnosperms average 13 c 21 0 and angiosperms mean 13 c 23 4

geochemical variations in andean basaltic and silicic lavas from the villarrica lanin volcanic chain 39 5 s an evaluation of source heterogeneity fractional crystallization and crustal assimilation at 39 5 s in the southern volcanic zone of the andes three pleistocene recent stratovolcanoes villarrica quetrupillan and lanin form a trend perpendicular to the strike of the andes 275 to 325 km from the peru chile trench basalts from villarrica and lanin are geochemically distinct the latter have higher incompatible element abundances and la sm but lower ba la and alkali metal la ratios these differences are consistent with our previously proposed models involving a a west to east decrease in an alkali metal rich high ba la slab derived component which causes an across strike decrease in degree of melting or b a west to east increase in the contamination of subduction related magma by enriched subcontinental lithospheric mantle silicic and mafic lavas from the stratovolcanoes have overlapping sr nd and o isotopic ratios silicic lavas also have geochemical differences that parallel those of their associated basalts e g rhyolite from villarrica has lower la sm and incompatible element contents than high sio2 andesite from lanin at each volcano the most silicic lavas can be modelled by closed system fractional crystallization while andesites are best explained by magma mixing apparently crustal contamination was not an important process in deriving the evolved lavas basaltic flows from small scoria cones 20 35 km from villarrica volcano have high incompatible element contents and low ba la like lanin basalts but trend to higher k rb 356 855 and lower 87sr 86sr 0 70361 0 70400 than basalts from either stratovolcano however all basalts have similar nd pb and o isotope ratios the best explanation for the unique features of the cones is that the sources of svz magmas e g slab derived fluids or melts of the subcontinental lithospheric mantle have varying alkali metal and radiogenic sr contents these heterogeneities are not manifested in stratovolcano basalts because of extensive subcrustal pooling and mixing this model is preferable to one involving crustal contamination because it can account for variable sr isotope ratios and uniform nd and pb isotope ratios among the basalts and the divergence of the cones from across strike geochemical trends defined by the stratovolcanoes

petrography of the neogene lignite from the sofia basin bulgaria abstract the lignite seam from the sofia neogene basin has been sampled and the petrographical composition was determined the coals contain high contents of macerals from the huminite group the prevailing macerals from that group were textinite ulminite and attrinite phlobaphinite densinite and gelinite were observed rarely dominant macerals from the liptinite group were mainly suberinite resinite sporinite and cutinite the amounts of the alginate liptodetrinite and fluorinate were insignificant the coal was very poor of macerals from the inertinite group fusinite semifusinite macrinite sclerotinite and inertodetrinite were represented them the main minerals were illite kaolinite halloyzite pyrite quartz calcite and dolomite anorthite amphibole augite chalcopyrite marcasite siderite witherite gypsum melanterite and jarosite were also determined the huminite maceral amount was highest in low part of the seam and lower in the middle part the higher amount of the liptinite macerals was located in the middle and upper parts of the seam inertinite macerals were distributed uniformly on the seam profile and their amount was very low in the middle part of the seam the middle part of the seam was contained highest amount of all minerals illite was prevailing clay mineral in the middle part and kaolinite predominates in the low and upper parts of the seam the type of the mire was determined as mesotrophic bog forest by calder et al bull soc geol fr 162 1991 283 according to the ground water index gwi and vegetation index vi calculated on the base of the maceral content according to the petrography content the gelification index gi and the tissue preservation index tpi the peat bog probably originated as a fresh water raised forest swamp

a re evaluation of the eskisehir fault zone as a recent extensional structure in nw turkey abstract the eskisehir fault zone efz one of the major active structures within the anatolian platelet is investigated in a 100 km long sector between bozuyuk and alpu in vicinity of eskisehir the morphotectonic observations indicate that throughout the studied area the efz extends wnwwards as a ca 15 km wide belt and is composed of some 21 fault segments 5 25 km long these segments form a north dipping southern set and two south dipping northern sets all together working both sides of the eskisehir graben the faults are dominantly normal in character with a slight right lateral component in the westernmost areas the estimated total vertical displacement on certain northern and southern fault segments exceeds 450 m in order to estimate the initiation age of the efz a brief stratigraphic review is given the generally horizontal pliocene terrestrial deposits are separated from the miocene succession by a low angular unconformity and are cut in turn by the efz sedimentological data show that neither the distribution of the pliocene depositional environments and their paleocurrent directions nor the preserved pliocene basal unconformity surface have a genetic relation to the efz these data strongly suggest that the efz is a younger post pliocene active normal fault zone with low rates of deformation

petrographic geochemical and mycological aspects of miocene coals from the novaky and handlova mining districts slovakia abstract fungi have once again become a topic of interest to coal scientists in their roles as agents of maceral formation recent works have demonstrated that fungi occur in association with woody remains resins and cuticles in coalified materials of a variety of ages in addition to coal balls and compression impression fossils where they are already well known these forms however have only been viewed as cross sections along a polished plane assigning the fungi to family much less determining which fungi they represent is very difficult in this orientation fungal identifications are necessary to the continuance of this research into the origin of coal macerals because of the need to know if macrinite begins to form prior to incorporation into the peat which could be demonstrated by its association with symbiotic and parasitic rather than saprophytic fungi this study examines the fungal remains recovered from eight coal samples from miocene age coals in the novaky and handlova mining districts of slovakia with the aim of making this distinction these samples were collected in slovakia as part of the us geological survey s world coal quality inventory program and provided to the authors the samples were processed using the o keefe technique for subbituminous coals and mounted for observation in transmitted light forms were identified using published works and consultation with a modern mycologist forms recovered through palynologic processing were compared to and correlated with forms seen in cross section under reflected light

a fault controlled newly discovered eskisehir alpu coal basin in turkey its petrographical properties and depositional environment abstract recent findings suggest that turkey contains about 15 billion tons of coal within its borders a small proportion of it nw part is bituminous but the rest is sub bituminous and lignite coal about 80 of the coals are utilized in power generation the newly found coal field alpu basin contains about 1 3 billion tons of coal the coal basin is a fault controlled and deeply buried basin which is close to the industrial areas in turkey in the studied area there are two coal horizons in the middle miocene aged m2 unit the average mineable coal seam thickness is approximately 13 14 m in order to determine the coalification degree petrographic composition and depositional environment of the coals petrographic and xrd analyses were conducted on coal samples taken from three boreholes which were drilled by mta in the eskisehir alpu basin according to the astm classification the rank of the coals is sub bituminous alpu coals contain two prominent types of maceral assemblages either containing high amounts of funginites macrinites ulminite and gelinites or high amounts of liptinites associated with detrital huminites attrinite and densinites the first type exhibits rather more homogeneous features but the second has a more complex mixed appearance with detrital macerals intensive lineation laminations and considerably higher pyrite contents the alpu coals contain montmorillonite heulandite quartz pyrite gypsum kaolinite illite illite montmorillonite orthoclase and clay minerals which indicate variation in the ph conditions the tissue preservation index tpi and gelification index gi indicate a limnic environment the sample points are located between open marsh and clastic marsh areas on the tpi gi diagram this case indicates that the water table was variable during the coal formation

changes in the volume and salinity of lake khubsugul mongolia in response to global climate changes in the upper pleistocene and the holocene two gravity cores 1 1 and 2 2 m long of deep water bottom sediments from lake khubsugul mongolia were studied the holocene biogenic silica and organic matter rich part of the first core was subjected to ams radiocarbon dating which placed the date of dramatic increase of pelagic diatoms 40 cm below sediment surface at a calendar age of 11 5 cal ky bp icp ms analysis of weak nitric acid extracts revealed that the upper pleistocene compared to the holocene samples were enriched in ca cinorg sr mg and depleted of u w sb v and some other elements transition to the holocene resulted in an increase of total diatoms from 0 to 108 g 1 of bisi from 1 to 20 of organic matter from 6 the bolling allerod younger dryas holocene abrupt climate oscillations manifested themselves in oscillations of geochemical proxies a remarkable oscillation also occurred at 22 cm ca 5 5 ky bp the pleistocene section of the second longer core was enriched in carbonate co2 up to 10 and water extractable so42 up to 300 times greater than that in holocene pore waters all this evidence is in an accord with the earlier finding of drowned paleo deltas at ca 170 m below the modern lake surface of the lake dokl akad nauk 382 2002 261 and suggests that due to low ca 110 mm regional precipitation at the end of the pleistocene lake khubsugul was only 100 m deep and that its volume was ca 10 times less than today

late glacial to middle holocene climate and environmental changes as recorded in lake dood sediments darhad basin northern mongolia abstract the paper presents new data on climatic lake level and environmental changes in the darhad basin northern mongolia during the late glacial and early to middle holocene two cores dn1 and dn2 from lake dood were investigated using the following proxies grain size total carbon tc total inorganic carbon tic total organic carbon toc total nitrogen tn total sulfur ts 13c 18o and diatom our reconstructions indicate that dramatic climatic and environmental changes occurred several times since ca 14 ka cal bp a cold and dry climate of the late glacial changed to a relatively cold and wet climate starting around 9 5 ka cal bp in response to an early holocene humidization a generally warm and humid climate prevailed in the region at ca 7 8 5 8 ka cal bp later on after 5 8 ka cal bp the climate became cooler and drier the darhad paleolake the predecessor of lake dood disappeared during the late glacial to early holocene times and started to reappear since ca 9 5 ka cal bp lake dood fluctuated considerably in response to changes in precipitation or and in ground ice melting between 9 5 and 5 8 ka cal bp and started to decrease at 5 8 ka cal bp

quality variations in the high sulphur lignite of the neogene beypazari basin central anatolia turkey abstract during the miocene a number of fault bounded basins developed in central anatolia turkey one such basin at cayirhan near beypazan contains thick laterally extensive lignite seams this basin was filled initially with coarse clastic material upward fining of the clastics during basin fill with an increase in the amount of clay and carbon content led to the development of relatively shallow linmic basins in which extensive peat deposits accumulated in low lying mires these lignites are characterized by their high sulphur and ash contents up to 8 2 s and 68 3 ash on an air dried basis studies of the sulphur and ash contents reveal three types of distribution namely vertical variation within individual seams variation between the seams and lateral variation across the basin in the case of the sulphur content vertical variation within and between the seams is related to variations in the amount and source of the sulphate in the mire water and the lateral variation is probably related to structural topographic control of the mire at the time of formation variation in the ash content within the seams is probably the result of depositional processes at the time of mire development variation between seams is recognized due to the presence of ubiquitous zeolites in the mineral matter namely heulandite in the first seam and analcime in the second seam this is probably the result of variations in the chemistry of the original volcanoclastic or clastic material associated with the lignite or of variations in the chemistry of the circulating fluid there is a broad east west lateral variation across the basin in the ash content of the seams probably resulting from variations in the amount and rate of clastic or volcanoclastic influx into the mire at the time of formation related to structural topographic controls

seismicity near the slip maximum of the 1960 mw 9 5 valdivia earthquake chile plate interface lock and reactivation of the subducted valdivia fracture zone understanding the processes behind subduction related hazards is an important responsibility and major challenge for the earth sciences few areas demonstrate this as clearly as south central chile where some of the largest earthquakes in human history have occurred we present the first observation of local seismicity in the villarrica region 39 40 s based on a temporary local network of 55 stations installed from the chilean coast into the argentinian back arc for one year while consistent with the chilean national catalog ssn our results allow us to observe smaller magnitudes with a completeness of about 2 0 and image the geometry of the wadati benioff zone from the chile trench down to 200 km offshore a gap in interplate seismicity is observed in the region of the 1960 valdivia earthquake slip above the interface two offshore seismicity clusters possibly indicate ongoing stress relaxation in the subducting nazca plate we find a prominent seismicity cluster along the extrapolated trace of the oceanic valdivia fracture zone vfz the seismicity cluster is observed between 70 and 130 km depth and comprises mainly strike slip events it indicates weakening and reactivation of the major vfz by dehydration of oceanic crust and mantle interpreting the subducted vfz section as a localized reservoir of potential fluid release offers an explanation for the villarrica volcanic complex that is located above the reactivated vfz and shows the highest volcanic activity in south america crustal seismicity is observed near puyehue volcano which recently started to erupt june 2011 key points we observe local seismicity near the 1960 valdivia maximum slip region the subducted valdivia fracture zone is reactivated by fluid release the seismogenic zone is free of seismicity events occur at faults and volcanoes

composition and mode of occurrence of mineral matter in some colombian coals abstract the minerals in a range of colombian coal samples selected to represent the principal coal mining regions have been investigated using low temperature ashing and quantitative x ray diffraction techniques and the results compared to information from chemical analysis and mossbauer spectroscopy studies kaolinite illite interstratified illite smectite and quartz are the dominant mineral matter components in almost all of the coal samples with small but significant proportions of pyrite up to around 15 of the mineral matter being present in around half of the samples studied other minerals present in particular samples include chlorite muscovite paragonite ankerite dolomite calcite and siderite along with phosphate minerals apatite and goyazite jarosite and coquimbite are also noted in some of the pyrite bearing coals probably representing oxidation products of the pyrite developed with exposure or storage bassanite is present in the low temperature ash of some coals and in one sample occurs along with significant concentrations of hexahydrite alunogen tschermigite and paraluminite all of which were probably derived from interaction of inorganic elements in the organic matter with organic sulphur during maceral oxidation quantitative analysis of the minerals in the low temperature ash of the coal samples using rietveld based x ray diffraction techniques provides results that are consistent at least for the most abundant elements with the chemical composition of the coal ash as determined by standard analysis procedures the evaluation of mineral rich concentrates by mossbauer spectroscopy also provides results consistent with the xrd data especially as regards pyrite and some of the sulphate components optical microscopy indicates that much of the pyrite and in some cases also the carbonates occurs as anhedral crystals finely disseminated in the maceral components as aggregates of crystals including pyrite framboids as fine grained crystals replacing liptinite and as fracture fillings some sub angular to rounded quartz grains are also present possibly of detrital origin but most other minerals including the clay minerals occur mainly as aggregates of intimately admixed mineral and maceral constituents

the new bdp 98 600 m drill core from lake baikal a key late cenozoic sedimentary section in continental asia abstract the new 600 m drill core bdp 98 from the academician ridge of lake baikal recovered a continuous sedimentary record of the past 10 ma the entire section is represented by lacustrine sediments which gradually change from distal deltaic facies at the bottom of the section to fine undisturbed hemipelagic sediments of the upper 300 m interval the entire 10 ma lacustrine section contains abundant diatoms thus allowing extension of plio pleistocene diatom and biogenic silica records into the miocene above the matuyama gauss paleomagnetic reversal boundary the bdp 98 record contains clearly delineated glacial interglacial lithologic cycles below this boundary the diatom signal is quite different average diatom contents are higher and variations are of lower amplitude although most likely paleoclimatic in origin these variation presumably reflect past changes in the moisture regime of southeast siberia under conditions of warm subtropical climate during the miocene and early middle pliocene the continuous bdp 98 drill core which covers the hiati present in the composite continental sections of the baikal region is a key section for reconstructing the neogene quaternary climatic evolution of continental asia the bdp 98 section also places several important time constraints on the rifting history of lake baikal by providing reliable correlation of lithological and physical properties of the drill core sediments with calculated positions of the acoustic reflection boundaries interpreted from multichannel seismic studies the lithologic composition indicates that on the stable block of academician ridge where the bdp 96 and bdp 98 drill sites are located acoustic reflection boundaries are not associated with major erosional events but instead result from changes in sediment density and composition several lithologic indices further suggest that significant changes have occurred in the physics and chemistry of lake baikal waters affecting the carbonate equilibrium and oxygen regime of baikal

carbonate stable isotope signals in the 1 ma sedimentary record of the hdp 04 drill core from lake hovsgol nw mongolia abstract oxygen and carbon stable isotope ratios in carbonates from the hdp 04 drill core from lake hovsgol nw mongolia show an overall covariant relationship suggesting that for the most of the past 1 ma hovsgol remained a closed basin lake carbonate 18 o ratio is responsive to regional climate change a ca 1 5 basinwide 18 o shift has occurred with the onset of bolling allerod warming sensu lato followed by a ca 0 8 depletion during the younger dryas the post glacial 18 o shift of the same magnitude is recorded in bulk carbonates shells of two ostracod species and in wet sieved fine fraction 18 o shift is nevertheless positive this argues against changes in local temperature and hydrology as key driving mechanisms most likely lake hovsgol 18 o reflects a climate driven shift in the composition of regional precipitation tied into a distinct lithologic succession the radiocarbon dated late glacial 18 o shift apparently represents a template of the lake s response to glacial interglacial transitions a similar pattern of parallel changes in lithology and carbonate stable isotope composition is observed in at least 10 more intervals in the 1 ma record including the mis 20 mis19 transition at the brunhes matuyama paleomagnetic reversal boundary the comparison of carbon stable isotope ratios of untreated and in vacuo roasted bulk sediment with those of detrital carbonates suggests that clastic input of carbonates by lake tributaries does not affect the geochemistry of bulk carbonates in the hdp 04 section the profiles of bulk carbonate 18 o and 13 c in the pleistocene section of the hdp 04 drill core suggest at ca 15 4 ka at ca 100 m below today s level lake hovsgol still stood relatively high as compared with prior extended periods of time during late matuyama and early brunhes isotopically heavy 18 o and 13 c ratios during the mid late brunhes particularly in carbonate crusts and oolites are suggestive of past episodes of dramatic evaporative 18 o enrichment of lake waters despite the expectation of muted amplitudes of temperature and precipitation related isotope signals the sedimentary record from the sensitive water gauge basin of lake hovsgol has high potential for providing important constraints on past hydrologic evolution of continental interior asia during the pleistocene

magma ascent rates volcanoes can erupt explosively generating high columns of ash and occasional pyroclastic flows or they can erupt slowly forming lava flows and domes this variation reflects significant differences in mass eruption rate e g wilson et al 1980 mass eruption rates in turn are controlled by the rates of magma ascent through the volcanic conduit and the conduit size the magma ascent rate itself is a function of the pressure in the magma storage region the physical properties of the magma such as its density viscosity and crystallinity and the resistance to flow in the conduit that connects the magma storage zone to the surface papale and dobran 1994 mastin and ghiorso 2001 pinkerton et al 2002 sparks et al 2006 a number of important characteristics of volcanic eruptions are affected or controlled by the rate at which magma ascends from depth for example the bubble content i e vesicularity and the degree of crystallization that develop in the melt phase can be significantly different in rapidly vs slowly ascended magma in fact the inability of rapidly ascending magma to effectively lose exsolved gas may be one factor causing an eruption to change from effusive to explosive behavior as recently documented for the soufriere hills eruption on montserrat in the west indies sparks et al 1998 therefore in order to better understand the processes involved and the changes that occur in volcanic eruptions it is important to quantify the rates at which different magmas rise to the surface the fact that the rate of magma ascent controls a number of reactions that occur in volatile rich magmas suggests several ways to study magma ascent rates using reaction data and theoretical flow models one reaction that is a direct result of magma ascent is the exsolution of volatiles from the melt

diffusion coupling between trace and major elements and a model for calculation of magma residence times using plagioclase residence times of plagioclase crystals in magma reservoirs can be determined by modeling the compositional zoning of trace elements in these crystals we present a formulation to model diffusion of trace elements in plagioclase paying special attention to certain thermodynamic and kinetic aspects in particular we account for the compositional dependence on anorthite content of the chemical potential and diffusion coefficients of trace elements e g mg the choice of suitable boundary conditions and potential effects of diffusion in more than one dimension we show that contrary to intuition diffusive fluxes of trace elements may be coupled to major element concentration gradients and ignoring such coupling can lead to incorrect estimates of timescales we illustrate application of the model using plagioclase crystals from a suite of gabbroic xenoliths from a holocene dacitic lava flow of volcan san pedro chilean andes 36 s the inferred timescale for metasomatism of the xenoliths by evolved liquids is on the order of 100 30 to 148 yr and serves to illustrate how trace element zoning in plagioclase provides a window into timescales of magmatic processes inaccessible by isotopic or other methods

evolution of pennsylvanian late carboniferous peat swamps of the ruhr basin germany comparison of palynological coal petrographical and organic geochemical data abstract this study focuses on the reconstruction of the environment during peat swamp development eight coal and sedimentary organic rock bearing seam successions were examined all belonging to the duckmantian pennsylvanian late carboniferous 410 samples were analysed with coal petrographical methods 155 of these also by palynological methods in addition on 55 samples organic geochemical investigations were carried out with respect to n alkanes and iso alkanes the established coal petrographical parameters gelification index gi tissue preservation index tpi groundwater index gwi and vegetation index vi were used to characterize different periods of peat swamp development furthermore the new index wci water cover index was introduced to reflect water level conditions by using the ratio between hydrophilous hygrophilous and mesophilous plants in this study the index is based on palynological data but can be equally applied when quantitative macrofloral counts are available gi versus tpi values show two general trends of peat swamp evolution low gi and tpi values as indicator for drier swamp conditions like ombrogenous mires and high gi and tpi values which show a trend to water covered environments like topogenous mires in addition ash yields and gwi versus vi data also emphasize a general trend from topogenous to ombrogenous mires a decrease in water level towards the top of the seams and thus resulting in the development of domed mires is reflected by the newly introduced wci hence these parameters show recurrent peat swamp successions characterized by mineral and vitrinite rich coals typical for topogenous swamps and an evolution towards inertinite liptinite rich coals with low ash yield typical for ombrogenous swamps n alkane ratios like the carbon preference index cpi pristane n c17 phytane n c18 pristane phytane and the n c17 n c27 relationship indicate a strong correlation of these parameters with thermal maturity e g cpi values correlate with vitrinite reflectance sulphur organic carbon s toc ratios are quite uniform in clastic rocks with low to moderate toc contents but highly variable in coals probably reflecting variable sulphate availability during deposition of peats sphenophyll rich floral assemblages are restricted to low sulphur environments