coal characteristics elemental composition and modes of occurrence of some elements in the isaalan coal balikesir nw turkey abstract this study uses coal petrography micro ftir mineralogical and geochemical analyses to determine the coal characteristics and controlling factors of elemental enrichments in the isaalan coal nw turkey the obtained data show that this subbituminous coal has a relatively low ash yield avg 19 high hydrogen content avg 5 4 and total s content avg 2 4 on an air dry basis the maceral composition along with micro ftir data on ulminite suggests that lignin and resin rich vegetation was predominant the coal facies data imply the precursor peat was accumulating under mesotrophic anoxic conditions where water level was high and fluctuating the mineralogical composition of the bulk coal samples is composed mainly of quartz pyrite and clay minerals and lesser amounts of feldspars and carbonates the statistical analysis of the bulk compositional data shows the major elements including al fe k na mg p and the vast majority of trace elements have inorganic affinity whereas b presumably has organic affinity the trace element concentrations are variable and especially as and elements including b ba cr cs ni sb and v are enriched compared to most world coals the enrichments and distributions of cr cs ni and v were controlled by clastic inputs into a palaeomire whereas as enrichments were controlled mainly by epigenetic and to a lesser extent syngenetic factors introduced so42 and as rich surface and groundwater from the basin margin area along with anoxic conditions in the palaeomire resulted in syngenetic formation of as bearing pyrite the circulating intra seam solutions later liberated as from syngenetically formed pyrite which resulted in as and ni rich overgrowths around framboidal and massive pyrite crystals these solutions could also easily mobilize b that was absorbed by organic matter therefore b enrichment appears to be related to epigenetic factors tectonic activities during coalification allowed hydrothermal solutions from neighbouring epithermal mineralisation to penetrate and circulate along with underground waters that leached overlying volcanoclastic volcanic strata and supplied a number of elements to the studied coal thus infilling as bearing pyrite and silica were formed mainly during coalification all these results suggest that as enrichment in the study area is more likely a combination of epigenetic factors and syngenetic detrital rather than volcanogenic contributions as suggested earlier for some other turkish coal deposits

a multidisciplinary study of the golbasi harmanli coal seam se turkey abstract this study focuses on the pleistocene golbasi harmanli coal deposit located in the east anatolian fault zone eafz se turkey the principal aim of the study is to determine factors that controlled peat accumulation by means of palaeontological data routine coal analyses proximate ultimate mineralogical composition based on xrd and sem edx and coal petrography the basin infillings consist of alluvial fluvial and lacustrine sediments palaeolake levels along with sedimentation were presumably controlled by the eafz during late pliocene to holocene times the investigated coal bearing zone is composed of a thick coal seam up to 39 m with thin clastic intercalations of fossiliferous claystones palaeontological data from these clastic bands imply that the coal accumulated during middle pleistocene times an uncommon period for the formation of thick coals in turkey we suggest that the movements of the eafz caused rapid subsidence and along with favourable climatic conditions allowed large peat accumulation in a relatively short period of time the results of proximate and ultimate analyses from 29 coal samples obtained from two cores show high ash yields av 32 relatively low sulphur content av 1 8 low net calorific value av 11 6 mj kg and low total carbon content av 35 5 on an air dry basis the mean random reflectances of eu ulminite b indicate a low rank coal maceral compositions and maceral indices indicate that the peat accumulated under limno telmatic mesotrophic conditions with peat forming vegetation being composed of mainly herbaceous plants ostracoda and mollusca fauna from intercalating clastic layers within the coal seam provide important information about the geographic distribution of fossil taxa environmental evaluation of the intercalations and the age of the studied coal seam the ostracoda species gomphocythere geareyi was identified within the coal seam for the first time humphcypris subterranea is the first fossil record of this ostracoda genus in turkey these along with the presence of the gastropoda subspecies bithynia phialensis syriaca imply a transport into the palaeomire via migratory birds from the eastern mediterranean areas discovery of humphcypris subterranea bithynia phialensis syriaca and the african originated genus gomphocythere in the golbasi harmanli coal deposit marks their northernmost worldwide occurrence

the use of one and two dimensional hydraulic modelling to reconstruct a glacial outburst flood in a steep alpine valley the hydrologic characteristics of the 1943 outburst flood from the glacier du mont mine switzerland are herein reconstructed using field evidence palaeostage indicators in conjunction with shallow water modelling techniques these techniques rely on accurately characterising the hydraulic roughness of the channel the water height established as boundary conditions and the main flow path during the former flood but the selection of appropriate parameter values can be problematic and hence there is uncertainty in the estimated discharge in this study minimal flow discharge estimates derived from one dimensional modelling were found to vary between 429 and 557 m3 s 1 as the hydraulic roughness ks and water height at the inlet were varied over a realistic range of values 0 8 1 4 m and 3 31 6 m respectively whereas flow rates derived via two dimensional modelling were confined in a narrower lower range of 358 454 m3 s 1 this degree of sensitivity to bed roughness ks boundary conditions and the spatial dimensions of the modelling approach is for the one dimensional modelling higher than reported in previous studies but the precision of flow discharge values reconstructed using the two dimensional modelling approach appears to be acceptable even for floods in the very steep valley 0 1 m m that is subject of this study

coal characteristics palynology and palaeoenvironmental interpretation of the yenikoy coal of late oligocene age in the thrace basin nw turkey abstract the yenikoy coal field is located in a narrow area between the black sea coast and the istranca standrja mountain in the thrace basin the aims of this study are to characterize coal petrographical mineralogical palynological geochemical and sedimentological properties of the yenikoy coal deposit and to reconstruct palaeoenvironmental conditions during peat accumulation a total of 9 coal samples collected from the coal seam section are almost entirely composed of xylite rich lithotype and are characterized by low ash yield 7 9 21 1 average 13 6 on dry basis and high total s contents 1 0 3 7 average 2 2 on dry basis the macroscopic features maceral composition and coal facies suggest that the peat was accumulated under mesotrophic anoxic conditions and the peat forming vegetation consisted mainly of arboreal species e g cupressaceae ulmus carya zelkova alnus pterocarya and quercus the low hi values of the analysed samples are presumably related to presence of xylite rich lithotype rather than the dominance of herbaceous plant and or low preservation of organic matter in the palaeomire even though relatively b enrichments high total s contents and weak anomalies of some rey e g y ce and gd in the analysed samples could refer possible sea water influence into palaeomire in the study area during late oligocene the sedimentological and palynological freshwater algaes pediastrum spirogyra and mougeotia data that indicate the palaeomire was located within a delta plain environment where small freshwater lakes and or ponds developed the statistical analysis and sem edx data show the vast majority of elements in the analysed coal samples have inorganic affinity the major elements al k and enriched elements like b v cr hg and u seem to be affiliated with aluminosilicate minerals whereas fe ni and as have probably sulphide affinity the detrital presences of apatite crystals as detected by sem edx analysis indicate that rey have mainly phosphate affinity in the analysed samples vertical distributions of the elements and ash yields suggest that the detrital input ratio was changeable and controlled some elemental enrichment during peat accumulation these variations could be related to development of and fluvial conditions in the study area which interrupted peat accumulation several times during late oligocene

a new distinct mechanism of river bank erosion in a forested catchment abstract it has been thought that the two main processes responsible for river bank retreat are the removal of particles or layers of material by flow erosion or sloughing and collapse by slumping a third process involving the development of a subsurface cavity after washout of gravels which is succeeded by slow subsidence of a segment of the former channel bank has been identified at a site in the new forest southern england the process was monitored over a 9 month period and was observed to be assisted by the hydrological effects of a dam of coarse woody debris across the channel as these dams occur frequently the process is likely to have occurred elsewhere along channels in forested areas

depositional environment of oil shale within the second member of permian lucaogou formation in the santanghu basin northwest china abstract the non marine santanghu basin in northwest china hosts one of the richest and thickest permian lacustrine source rock intervals in the world conventional oil in jurassic sandstone reservoirs and tight oil in the tuffaceous permian tiaohu formation were sourced from mudrocks in the underlying second member of lucaogou formation which also have tight oil potential proved by recent commercial discoveries based on inorganic and organic geochemistry organic petrography and stable isotope geochemistry the depositional environment and the tight oil potential of the second member of permian lucaogou formation were investigated the data imply a gradual evolution of the depositional environment from a stratified saline to a freshwater lake the succession can be subdivided into a lower middle and an upper unit each characterized by decreasing water salinity high bioproductivity has been caused by the bloom of algae and photosynthetic cyanobacteria water column stratification accelerated the activity of methanothrophs as indicated by low 13c values of hopanes biomarker composition provides evidence for decreasing contributions of cyanobacteria to the biomass and increasing abundance of prasinophytae compared to other algae with decreasing salinity enhanced terrigenous organic matter input appeared during periods of high freshwater inflow low total organic carbon toc contents in the lower unit are most likely caused by rapid sedimentation rate high bioproductivity and excellent preservation conditions resulted in high toc contents in the middle unit terrigenous organic matter input increased together with fresh water inflow in the upper unit resulting in high toc values during periods of possibly low sedimentation rates in a deep water column the samples of the second member exhibit a good to very good potential to generate conventional oil high toc and extractable organic matter yields together with the thickness of the fine grained sediments show that the middle and upper units of the second member of lucaogou formation hold significant tight oil potential mineralogical composition of this dolomite rich shale with respect to abundance of brittle minerals including quartz and carbonates and rare clay testifies a good tight oil potential

heat production in an archean crustal profile and implications for heat flow and mobilization of heat producing elements we have measured concentrations of heat producing elements th u and k in 58 samples representative of the main lithologies in a 100 km transect of the superior province of the canadian shield from the michipicoten wawa greenstone belt near wawa ontario through a domal gneiss terrane of amphibolite grade to the granulite belt of the kapuskasing structural zone near foleyet this transect has been interpreted as an oblique cross section through some 25 km of crust uplifted along a major thrust fault and thus provides an opportunity to examine in detail a continuous profile into deep continental crust of archean age mean heat production values for these terranes based on aereal distribution of major rock types and calculated from their th u and k concentrations are michipicoten greenstone belt 0 72 w m 3 wawa domal gneiss terrane amphibolite grade 1 37 w m 3 kapuskasing granulites 0 44 w m 3 among the silicic plutonic rocks tonalites granites and their derivative gneisses the relatively large variation in heat production correlates with modal abundances of accessory minerals including allanite sphene zircon and apatite we interpret these variations as primary pre metamorphic the relatively high weighted mean heat production of the domal gneiss terrane can be accounted for by the larger proportion there of late stage th u and k rich granitoid plutons these may have been derived from the underlying kapuskasing granulite terrane leaving it slightly depleted in heat producing elements transport of th u and k therefore could have taken place in silicate melts rather than in aqueous or carbonic metamorphic fluids this conclusion is supported by the lack of a statistically significant difference in heat production between tonalites tonalite gneisses and mafic rocks of amphibolite versus granulite grade the pre metamorphic radioactivity profile for this crustal section is likely to have been uniformly low with a mean heat production value less than 1 w m 3 this result is distinctly different from measured profiles in more silicic terranes which show decreasing heat production with depth this implies fundamental differences in crustal radioactivity distributions between granitic and more mafic terranes and may be an important factor in selective reactivation of lithologically different terranes possibly resulting in preferential stabilization of basic terranes in the geological record our results indicate that a previously determined apparently linear heat flow heat production relationship for the kapuskasing area does not relate to the distribution of heat production with depth low but significant heat production 0 4 0 5 w m 3 continues to lower crustal depths with no correlation to the depth parameter from the linear relationship this low heat production may be a minimum average granulite heat production and suggests that in general heat flow through the moho is 8 10 mw m 2 lower than the reduced heat flow calculated from the heat flow heat production regression

variation of radiogenic heat production rate in 2 8 1 8 ga old rocks in the central fennoscandian shield abstract we present results of a geochemical survey based on 1150 outcrop samples for heat production studies in a e w oriented band 120 km 500 km located approximately between 62 and 63 n in finland the central fennoscandian shield the results provide representative averages of heat production rate in the studied tectonic units but also demonstrate the heterogeneity and spatial variation in radiogenic heat production rate of the precambrian lithosphere the study area covers formations from the archaean granite greenstone terrain in the east via a palaeoproterozoic mobile belt to a major granitoid complex surrounded by schist belts in central and western finland in this study we review the heat production rates as calculated from the u th and k total analyses and densities of the samples and the relations of heat production rate values with major tectonic setting lithological types major composition and petrophysical properties of rocks the data is further correlated with heat flow values measured in boreholes and applied in a lithospheric heat production model in the central part of the shield generally heat production rate increases from archaean to proterozoic rocks in e w direction but this trend is relatively weak and often overrun by lithological variations the arithmetic means are 1 1 1 3 w m 3 in the archaean domain 1 3 0 6 w m 3 in the hoytiainen autochthonous proterozoic domain 1 2 0 5 w m 3 in the suvasvesi domain characterized by allochthonous proterozoic cover 1 0 0 6 w m 3 in the proterozoic raahe ladoga mobile belt 1 3 1 1 w m 3 in the proterozoic rantasalmi haukivuori domain 1 6 0 8 w m 3 in the central finland granitoid complex and 1 4 0 8 w m 3 in the bothnian schist belt the standard deviations of the mean values are considerable and reflect the heterogeneity of heat production all distributions overlap heat production rate shows spatial variations which range in scale from kilometres to tens of kilometres well defined systematic variations of heat production rate values with either sio2 content density or p wave velocity could not be found although the correlations are statistically significant at 1 risk level the correlations are weak and scattered and sometimes opposite in sign in the major rock groups plutonic metavolcanic and metasedimentary heat flow density measured in boreholes increases with increasing heat production rate but the present data do not support a strict linear dependence between the variables and the regression line parameters vary depending on the applied heat production values drill core analyses versus hole site averages from the present study this indicates that the heat production rate is spatially heterogeneously distributed in the scale of the boreholes and their formations a lithospheric heat production model was constructed using data from the present study for the upper crust literature data for lower crustal xenoliths in the study area and a xenolith derived heat flow density value for the mantle the total crustal contribution to the surface heat flow density 37 mw m 2 from radiogenic heat sources is calculated as 26 mw m 2 and the contributions from the lower middle and upper crust are 4 11 and 11 mw m 2 respectively

carbonate minerals in bulgarian coals with different degrees of coalification abstract coals of various rank ranging from lignite to anthracite and originating from seven coal basins in bulgaria were investigated for the occurrence and types of carbonate minerals the following carbonates are present in their characteristic forms calcite clastic organogenic cryptograined xenomorphic massive and infiltrational siderite cryptograined xenomorphic both infilling and replacing massive euhedral framboidal and infiltrational both fracture filling and cleat filling dolomite cryptograined xenomorphic massive and infiltrational and magnesite carbonate mineralization depends on the penetration of ready mineral forms and mineralized solutions during peat genesis and the infiltration of mineralized solutions during coalification the mineral composition of the carbonates in the coals studied and the occurrences of the various carbonate minerals depend on the combination of a series of factors such as 1 the presence of carbonate rocks in the province feeding the peat bogs 2 the way and capacity of feeding 3 acidity ph and reducing conditions eh of the environment 4 tectonic situation during the peat genesis and 5 availability of infiltrational mineral solutions during coalifications no infiltrational carbonate mineralization was found in the lignites studied due to the combination of the above five factors bituminous coals from the balkan basin and the anthracite from svoge are characterized by the greatest variety of carbonate minerals and their forms

late quaternary environments of the carpentaria basin australia abstract quaternary variations in the level of the sea have exposed the shallow 29 000 km2 but shallow maximum depth s 4 0 kyr the pollen assemblages closely resemble the black soil plains presently found along the southern gulf thus the biogeographic and climatic barrier across the australia papua new guinea land bridge has remained largely intact in spite of the range of environmental conditions that have occured during the last

distribution of sulfur and pyrite in coal seams from kutai basin east kalimantan indonesia implications for paleoenvironmental conditions abstract thirteen miocene coal samples from three active open pit and underground coal mines in the kutai basin east kalimantan indonesia were collected according to our microscopical and geochemical investigations coal samples from sebulu and centra busang coal mines yield high sulfur and pyrite contents as compared to the embalut coal mine the latter being characterized by very low sulfur

analysis origin and significance of mineral matter in coal an updated review abstract the material classed as mineral matter in coal embraces crystalline mineral materials as well as a range of inorganic elements that occur in non crystalline form this review outlines the methods that may be used to evaluate the percentage of mineral matter for a coal sample as opposed to the ash yield and to identify the minerals their individual percentages and their modes of occurrence within the coal the principal techniques include low temperature oxygen plasma ashing quantitative evaluation of x ray diffraction data observation using optical microscopy and a combination of observation chemical analysis and in some cases mapping based on scanning electron microscopy and related methods a range of other techniques may also be used to provide additional information on particular mineral matter components processes responsible for mineral matter formation include detrital input biogenic activity and authigenic precipitation at different stages of the coal s depositional and post depositional history differential migration of non mineral inorganic elements may also occur in lower rank coals and expulsion of non mineral inorganics may take place with rank advance knowledge of the mineral matter may be of assistance in understanding the modes of trace element occurrence with implications for assessing possible environmental impacts and also the potential for recovery of economic products from coal the behaviour of different mineral matter components at high temperatures is also discussed as well as methods for mineralogical analysis of ashes and other coal utilization products information from mineral matter studies may provide an improved basis for understanding coal formation and for evaluating the response of particular coals to different combustion gasification and coking processes

thermoluminescence dating studies of glacial silts from ontario to develop procedures for the direct dating of glacially related silts by thermoluminescence tl i have applied previously proposed techniques to three polymineralic 4 11 m samples from the toronto area furthermore one of these samples was studied in detail by isolating some mineral fractions the principal conclusion is that the tl of the lodgment halton till from woodbridge was not significantly reset during deposition whereas the tl of the waterlaid upper thorncliffe silt from the scarborough bluffs was reset as was the tl of the third sample wc st a massive silt from woodbridge that has been generally correlated with the glaciolacustrine sunnybrook diamict at the bluffs this conclusion follows from the observation of feldspar tl apparent ages of 140 ka for the 12 ka bp halton till and of 36 and 66 ka for the upper thorncliffe and wc st samples respectively the four laboratory factors that contributed most to inaccuracies in the tl apparent ages were 1 anomalous fading in the felds

petrology mineralogy and geochemistry of the ge rich coal from the wulantuga ge ore deposit inner mongolia china new data and genetic implications abstract the early cretaceous wulantuga high ge coal deposit in inner mongolia is one of the major coal hosted ge deposits in china this paper reports new data on the petrological mineralogical and geochemical compositions of 13 bench samples of the high ge no 6 coal from the wulantuga deposit and provides new insight into the origin and modes of occurrence of the minerals and elements present the no 6 coal has a low rank ro max 0 45 and is a low ash coal 8 77 the total content of inertinite 52 5 vol on average in most coal benches is higher than that of huminite 46 8 vol on average the dominant huminite maceral is textinite averages 43 9 and the dominant inertinite macerals are mainly fusinite averages 33 and semifusinite 12 5 along with trace portions of intertodetrinite secretinite funginite and macrinite fungus seen as the maceral funginite played a role in the development of degraded maceral forms in the wulantuga coals funginite is present in samples examined in this study but is not easily extracted during palynological studies recovered fungal taxa are saprophytes indicating woody decomposition prior to incorporation in the mire palynology revealed a sparse flora that is consistent with the early cretaceous age minerals in the coal include quartz kaolinite illite and or illite smectite gypsum pyrite and traces of rutile and anatase a varying proportion of bassanite was observed in the low temperature ashes ltas bassanite in the ltas was derived both from the dehydration of gypsum in the raw coals and from the interaction between organically associated ca and s during the low temperature ashing in addition to a proportion of detrital quartz fine grained and cell filling quartz of authigenic origin is also present pyrite is of syngenetic origin and derived from sulfate rich hydrothermal fluids compared to common chinese and world low rank coals the no 6 coal is enriched in be 25 7 g g f 336 g g ge 274 g g as 499 g g sb 240 g g cs 5 29 g g w 115 g g hg 3 165 g g and tl 3 15 g g germanium in the coal is organically associated and its enrichment is attributed to hydrothermal fluids from the adjacent granitoids beryllium is probably associated with ca and mn bearing carbonate minerals and to a lesser extent with clay minerals rather than with organic matter fluorine largely occurs in clay minerals kaolinite and illite the elevated concentrations of tl hg as and sb are mainly distributed in pyrite and were derived from the same hydrothermal source the high w in the coal occurs in both the organic matter and the authigenic quartz illite is the major carrier of cs in the coal the accumulation of rare earth elements ree in the coals had a polygenetic and multistage nature including two syngenetic stages early hydrothermal and terrigenous and one diagenetic late hydrothermal stage the ree distribution patterns of the early hydrothermal and terrigenous stages were characterized by the enrichment of medium ree m type ree and light ree l type ree respectively a h type ree distribution pattern hree enrichment occurred in the late diagenetic hydrothermal stage the high ge wulantuga coals are also abnormally enriched in precious metals gold pt and pd in the coals calculated from their concentrations in the ltas are 3 5 25 8

radiogenic heat production in the upper third of continental crust from ktb the heat production rate of continental crystalline rocks was determined from cores and drill cuttings recovered from depths up to 9 1 km in boreholes drilled by the continental deep drilling program of germany ktb the drilled rocks are mainly gneisses and metabasites based on a large amount of data the comparison of laboratory and in situ determinations by logging shows good agreement the loss of radioactive elements in drill cutting samples at the shaker tables was minimized by using a broad range of available fragment sizes the data reveal a clear lithological dependence of the heat production rate of the metamorphic rocks at ktb the lithologically caused variations of the heat production rate have a wavelength in the order of the drilled depth and therefore they cover up any decreasing trend if there is one below 6 km tectonic elements such as fault zones play also an important role in the observed vertical distribution despite the availability of data for the upper third of the crust models to predict temperatures for greater depths still contain uncertainties

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

a comparative study on structural differences of xylite and matrix lignite lithotypes by means of ft ir xrd sem and tga analyses an example from the neogene greek lignite deposits abstract the ft ir spectra for both neogene xylite and matrix lignite samples from six different greek lignite deposits nw greece show significant differences in particular in the aliphatic stretching region 3000 2800 cm 1 the intensities of the vibrations are more prominent in the xylite lithotype as in the matrix lignite lithotype the intense bands in the region 3402 3416 cm 1 are attributed to oh stretching of h2o and phenol groups for both xylite and matrix lignite lithotypes the bands at 3697 cm 1 and 3623 cm 1 as well as at 538 cm 1 and 470 cm 1 which are more evident in the ft ir spectra of the matrix lignite are attributed to a higher clay content in the samples of this lithotype data resulting from x ray diffraction analysis xrd scanning electron microscopy sem and thermoanalytical methods tg dtg and dta indicate main differences of the xylite and matrix lignite lithotype as well typical peaks in x ray diagrams confirm the high content of clay minerals in matrix lithotype and their minor contribution in the xylite lithotype scanning electron microscopy sem combined with the ft ir and xrd results reveals prevalence of gypsum pyrite marcasite quartz and clays in the matrix lignite lithotype as compared with the xylite lithotype and also textural differences such as the heterogeneity in the mass of matrix lignite and the homogeneity of the xylite compositional differences of the examined lignite materials as identified by ft ir were also confirmed by tg dtg dta while cellulose decomposition was observed by an endothermic peak of dta curves at around 360 c in the xylite samples lignin degradation became a prominent process observed in the temperature range from 200 c to 400 c in the matrix lignite samples this was also observed by an exothermic peak on dta curves each of the heat effects was accompanied with a partial mass loss registered on tg curves as a whole the data resulting from the combined research by means of ft ir xrd sem and tg dtg dta of both xylite and matrix lignite lithotypes confirm the significant differences between these two lignite lithotypes reflecting their different structure texture and maturity stage

occurrence and morphology of pyrite in bulgarian coals abstract coals with different degrees of coalification ranging from lignite to anthracite from seven bulgarian coal basins have been investigated the forms of pyrite and their distribution have been established the types found are massive pyrite represented by the homogeneous cluster like and microconcretionary varieties framboidal pyrite appearing in inorganic and bacterial forms euhedral pyrite which is either isolated or clustered anhedral pyrite in its infilling and replacement varieties and infiltrational pyrite as a replacement or infilling mineral most of the forms of the euhedral framboidal and massive pyrite developed during peat deposition the anhedral replacement pyrite formed in the peat bed during early diagenesis infiltrational pyrite filled fractures and cleats formed during the diagenesis catagenesis and metagenesis both similarities and differences with respect to the distribution of the pyrite types have been determined between coals of different ranks from bulgarian coal basins these differences are due to the presence of fe and s in the rocks adjacent to ancient peat bogs the activities of ground and surface waters which brought fe and s into the peat bogs the geochemical character ph and eh of the peat bogs and the sulphur bacteria development and the tectonic situation during diagenesis catagenesis and metagenesis

determination of thermal conductivity for deep boreholes two methods for thermal conductivity determinations on rock cores and fragments were tested on a suite of samples from the kontinentales tiefbohrprogramm der bundesrepublik deutschland ktb superdeep drill hole in germany they were also compared with estimates of thermal conductivity using the mineral composition of the rock and physical well logs and with in situ thermal conductivity measurements laboratory methods provide reasonably precise determinations of the thermal conductivities of both solid core 5 and drill cuttings 10 at room temperature and pressure the most common methods presently used for crystalline rocks are the steady state divided bar db technique and the transient half space line source ls sample preparation and measurement times are comparable for the db and ls with sample preparation being more time consuming on average for isotropic rocks there is little to choose from between the two methods which both give reliable values of conductivity in the vertical direction the ls is easier to set up and use in field laboratory situations which renders it the preferred method for field reconnaissance the gneissic crystalline rocks penetrated by the ktb boreholes typically have anisotropy of the order of 10 20 the db provides unambiguous values of conductivity in a given direction so its use is preferable for obtaining both principal conductivities and the vertical component anisotropy can be estimated using ls measurements in many different directions but the potential for large random errors is much greater than with the more straightforward db approach for deep research wells the difficulties of extrapolating laboratory results to in situ conditions particularly temperature present additional obstacles to determining heat flow laboratory measurements of water saturated samples under in situ conditions combined with in situ measurements and judicious use of calculations based on mineralogy and well log derived physical properties can aid in the accurate characterization of thermal conductivity in deep wells the application of different methods helped to link variations of heat flow with depth in the ktb hole to the anisotropy of thermal conductivity or thermal refraction and thus allowed the calculation of background heat flux in this geologically complex area

modelling floodplain flows using a two dimensional finite element model a prototype two dimensional finite element flow model for depth averaged free surface flows was developed for floodplain environments limited refinement of the model s physical representation was undertaken and the enhanced scheme applied to an 11 km river channel floodplain reach in the u k preliminary model results indicate that this modelling approach can be used to identify dynamic variations in the flow field parameters over length scales of the order of 10 100 m potentially such data have the ability to permit detailed analysis of short term floodplain sedimentary dynamics

a heat generation model for continental crust based on deep drilling in the baltic shield abstract this paper presents a heat generation model for the old continental crust on the basis of a new petrological model on the origin evolution and deep structure of the crust in which petrological geochemical and geophysical data obtained from the kola superdeep borehole and other deep boreholes drilled into the crystalline basement of the east european platform are taken into account the petrological section obtained from the borehole observations was extrapolated down to the moho boundary taking into consideration the evolution and generalized seismic model of the continental crust in our model the continental crust is subdivided into three layers a granite gneiss layer 0 17 km a charnokite enderbite layer 17 30 km and a basic layer including autochthonous restites of the protocrust 30 40 km the boundaries between the layers correspond to seismic surfaces k1 and k2 the crustal contribution to heat flow is estimated to be about 25 mw m2 52 of the total heat flow for the baltic shield and the mantle heat flow is 22 24 mw m2 a comparison is made between the heat generation model obtained in this study and the ones estimated from seismic velocity structure the difference in the heat generation value between these models may originate from the differing geological and tectonic history of the sampling localities

vertical distribution of heat production in the continental crust abstract using an experimentally established formula seismic velocity vp was converted to heat production a to investigate the vertical distribution of heat sources the conversion performed for a number of characteristic 1 d seismic crustal sections from various tectonic units in central europe yields a general decrease of a with depth z the pattern of decrease depends on geological age young tectonic units with high heat flow exhibit a more rapid decrease the depth dependence of a does not exactly follow the simple exponential law a z a 0 exp z d in general the logarithmic decrement d decreases with depth from 20 30 km at a depth of 10 km to about 10 km at the base of the crust in the uppermost 10 km layer of the crust a certain redistribution of u and th can occur by deep groundwater migration through microcrack networks at depths greater than 10 km geochemical constraints fairly constant th u and k u ratios suggest that the rate of decrease of the heat producing radioelements u th and k is similar

iron sulfide precipitation sequence in albian coals from the maestrazgo basin southeastern iberian range northeastern spain abstract deposition of important coal accumulations in the proximal areas of a delta estuary occurred in the maestrazgo basin during the middle albian late lower cretaceous these coals are characterized by high sulfur contents 4 18 in coal from the castellote subbasin and 7 16 in coal from the calanda subbasin dry basis a petrographic study of iron sulfide was carried out on the subject coals to deduce an iron sulfide precipitation sequence for five principal stages a early syngenetic stage b late syngenetic stage c syngenetic diagenetic stage d early epigenetic stage and e late epigenetic stage a sulfide precipitation control during the syngenetic stage carried out by different compounds liberated from organic matter during its coalification stages is deduced from the confrontation with other studies on coal differing in rank depositional environment and geographical location

the formation of caliche in soils of the mojave desert california abstract radiocarbon and 230th 234u dates of calcic horizons from calciorthid soil profiles in the mojave desert were used to calculate the rate of deposition of pedogenic caco3 a major period of caco3 deposition appears to have occurred about 20000 ybp forming calcic horizons below 100 cm depth during a climatic regime with greater effective rainfall than in the present the overall rate of deposition has been 1 0 to 3 5 g caco3 m2 yr during soil formation this rate is consistent with present day rates assuming that the atmospheric deposition of ca limits the process stable isotope ratios in calcic horizons indicate that caco3 precipitated from a soil environment with co2 of 15 5 13 c 12 c vs pdb and h2o of 2 0 18 o 16 o vs smow these values suggest that caco3 precipitates when seasonal drought simultaneously lowers soil pore pco2 and enriches soil water 18o by evaporation the role of soil calcic horizons in the global geochemical cycle of carbon is discussed

sulfur variability and petrology of the lower block coal member pennsylvanian in southwest indiana abstract the lower block coal member pennsylvanian atokan westphalian c is an economic low to medium sulfur low ash coal resource in the illinois basin sulfur content is generally low averaging 1 0 in the study area but varies over short distances higher sulfur areas occur as isolated pods and epigenetic pyrite increases significantly in the upper third of the selected columns in higher sulfur areas sulfur variations cannot be predicted by typical geologic characteristics such as roof lithology seam thickness or seam elevation petrographic analysis shows that pyrite is generally associated with brighter microlithotypes except in higher sulfur areas where infilling pyrite forms are associated with inertite higher sulfur areas reflect the water chemistry of the paleomire during and shortly after peat accumulation locally abundant pyrofusinite provided additional pore space for pyrite precipitation

relative sea level changes recorded by paralic liptinite enriched coal facies cycles middle jurassic muslingebjerg formation hochstetter forland northeast greenland abstract the middle jurassic muslingebjerg formation of hochstetter forland northeast greenland consists of a succession of shallow marine sandstones encasing four coal seams formed in low lying coastal mires the seams are up to 3 45 m thick and contain coal facies cycles with high liptinite contents up to 70 vol the cycles generally start with huminite rich bright or banded coal and end with dull coal or clayey coal coaly claystone the dull coals are characterized by a high proportion of liptinite commonly resinite and often mineral matter liptodetrinite resinite and cutinite dominate the liptinite maceral group similarity in the relative proportions of the liptinite macerals in the bright and dull coals and the general association of bright coal and dull coal with a high resinite concentration suggest that the dull coals represent a residue after selective removal of ligno cellulosic tissues in the precursor peat of primarily the bright lithotype the clayey coal coaly claystone lithotypes have high contents of mineral matter and commonly contain alginite and pyrite occurrence of pyrite in levels with high diasterane c 27 c 29 ratios and sometimes also alginite in the clayey coal coaly claystone lithotypes indicates a marine influence during flooding of the mires this suggests a causal link between base level rise in the coastal mires and relative sea level rise accommodation space available for thick peat accumulations was governed by overall relative sea level rise and the dulling upward cycles record outpacing of peat accumulation due to accelerated rise in base level relative sea level the muslingebjerg formation consists of four depositional sequences beginning with a thick coal seam resting on a sequence boundary peat accumulation reflects onset of base level rise in the coastal area and the coals represent the lower part of the transgressive systems tract the overlying shoreface sandstones form the upper part of the transgressive systems tract and a progradational highstand systems tract alternatively the two lower seams in the succession may form a transgressive regressive couplet separated by a lagoonal sandstone split in this case a sequence boundary occurs at the top of the upper regressive seam the dulling upward cycles within the coal seams represent parasequences or possibly higher order sequences minimum age estimates suggest that they accumulated over 4000 11000 yr

velocity reversal hypothesis a model approach hydraulic modelling of a riffle pool riffle sequence in a straight reach of dry creek near winters california indicates that while at low flow the mean section average velocity at riffles exceeds that of an adjacent pool during high flow the mean velocity of the pool exceeds that of adjacent riffles this supports the velocity reversal hypothesis which is based on limited field measurements of near bed flow velocity a velocity reversal does not occur at the same discharge in both riffle pool sequences modelled and a more detailed explanation is necessary to account for complex aspects of channel form and process in riffle pool sequences nevertheless the velocity reversal hypothesis helps to explain many of the observations and processes that operate in the riffle pool environment

paleoflood evidence for a natural upper bound to flood magnitudes in the colorado river basin the existence of an upper limit to the magnitude of floods in a region is a long standing and controversial hypothesis in flood hydrology regional envelope curves encompassing maximum flood magnitudes stabilize with progressive increases in the areal coverage and period of observation wolman and costa 1984 however the short lengths of conventional gaging records limit substantial advances in testing whether this stabilization is evidence of an upper limit in the colorado river basin there are 32 120 station years of gage data but the average period at a gaging station is only 20 years with most stations having less than 70 years of observation paleoflood magnitudes derived from sediments of large prehistoric floods from 25 sites on rivers in arizona and utah provide additional data to extend the records of the largest floods the paleoflood data identify the maximum flood discharges that have occurred on individual rivers over the last several hundred to several thousand years even with this increase in the observational period the largest paleoflood discharges do not exceed the upper bound of maximum peak discharges delineated by the envelope curve derived from the available gaged and historical records this result accords with the hypothesis of an upper physical limit for flood magnitudes and suggests that for the colorado river basin the upper limit can be approximated by existing systematic and historical data for large floods similar relationships also hold when paleofloods and gaged records are presented for the subregion of southern arizona

palaeohydrology and future climate change since the mid 1980s there has been growing concern that increasing concentrations of so called greenhouse gases will lead to global warming changes to regional climates and hence impacts on the environment society and economy the united nations environment program and the world meteorological organization in 1987 set up the intergovernmental panel on climate change ipcc which has reported on climate change predictions ipcc 1990a 1992a the possible impacts of climate change ipcc 1990b 1992b and strategies for mitigating the effects of climate change ipcc 1991 the ipcc second assessment is scheduled for publication in 1996 climate change science is essentially predictive it is trying to predict conditions during the twenty first century by far the most common approach is based around the use of global climate models gcms these numerical simulation models are used to predict the global and regional climatic effects of changing greenhouse gas concentrations and many climate change impact studies use scenarios based in some way on gcm simulations these scenarios are then used to perturb current climatic time series and fed through a catchment hydrological model to simulate river flows and other hydrological properties e g bultot et al 1988 lettenmaier gan 1990 arnell reynard 1993 and many others the two major problems with this approach lie in the definition of credible catchment scale scenarios from gcm simulations and the development of realistic hydrological simulation models the latter problem is fundamental to hydrological simulation whilst the former is peculiar to climate change impact assessments and arises for two reasons first gcms do not at present represent all the climatic processes in a realistic manner particularly those relating to the development of clouds and the interactions between the atmosphere and the land surface and second gcms operate at a very coarse spatial resolution some important atmospheric processes such as the development of meso scale circulation patterns and convective storms are therefore not simulated particularly well and whilst gcms can simulate large scale atmospheric features well regional and local climates are often not well reproduced the coarse spatial resolution also means that gcm output has to be interpolated down to the catchment scale a variety of techniques of varying degrees of sophistication have been used or proposed ranging from simple statistical interpolation through empirical relationships between large scale and local climate to the use of nested regional climate simulation models but all rely ultimately on the reliability of the gcm simulations of large scale climatic features arnell 1995a the other popular approach to climate impact assessment uses the past as an analogue for the future one variant uses the instrumental period in practice the last century another uses historical data and a third uses palaeoclimatic reconstructions

comparison of thermoluminescence and radiocarbon age determinations from late pleistocene alluvial deposits near sydney australia abstract radiocarbon and thermoluminescence tl age determinations have been obtained for a large pleistocene alluvial terrace on the nepean river near sydney new south wales australia the deposit was laid down by a braided river system prior to the last glacial maximum six thoroughly pretreated samples of charcoal and degraded wood buried within gravels at the base of the terrace yielded apparent 14 c ages of 37 000 42 000 yr b p these compare favorably with four tl determinations that gave apparent ages of 41 000 47 000 yr b p for the same deposit adjustment of the 14 c ages to take geomagnetic effects into account further improves the correlation between these two independent dating techniques in addition 14 c and tl correctly identified a reworked portion of the fine grained alluvial overburden as being substantially younger than the main body of the terrace these results augur well for the usefulness of tl age determinations of certain alluvial deposits

palaeoenvironmental reconstruction of the eastern part of the karapinar ayranci coal deposit central turkey abstract regional tectonic movements during the neogene period resulted in the development of several fault controlled basins in central anatolia many of these basins host economic coal deposits the recently discovered karapinar ayranci coal deposit is the most important one due to its large reserves c 1 8 gt and location in the vicinity of important urban areas the paper aims to reconstruct the palaeoenvironmental conditions before during and after coal formation in the eastern part of karapinar ayranci deposit by means of coal petrography and mineralogical data combined with sedimentological and palaeontological data the basinal infilling consists of mainly lacustrine fluvial and alluvial sediments the coal seams comprise several beds intercalating with claystone mudstone and marl the coal being lignite in rank displays high ash yield 36 4 wt on dry basis and high total sulphur content avg 7 7 wt on dry ash free basis facies diagrams and lithological features of the coal seams suggest that peat was accumulating under pure telmatic to limnotelmatic conditions however peat accumulation ceased several times due to a rise in water level therefore clastic e g quartz clay minerals and authigenic e g pyrite mineral contents are variable along the seam profile gastropod and ostracod fauna points to freshwater conditions in the palaeomire high total sulphur and evaporite mineral e g halite contents usually point to brackish saline conditions during peat accumulation however in case of the karapinar ayranci deposit high sulphur contents can be related to sulphate rich karstic aquifer which contributed to the palaeomire water supply

variation in pyrite size form and microlithotype association in the springfield no 9 and herrin no 11 coals western kentucky abstract channel samples of the springfield no 9 and herrin no 11 pennsylvanian desmoinesian westphalian d coals were acquired in three mines each in the western kentucky coal field pyrite was characterized petrographically in terms of its size form and microlithotype association within each coal seam significant variations in the amount of pyrite of certain forms occurred between the sites pyritic sulfur as determined chemically did not exhibit significant variation between the seams or between the sites the variation in dendritic pyrite in vitrite plus clarite between seams and between sites was highly significant and the variation in framboidal pyrite in vitrite plus clarite between sites was also highly significant

fluvial processes in a forested anastomosing river flood partitioning and changing flow patterns in an effort to further our understanding of multiple channel systems this paper presents data on the flood response of channels in one of the last wooded semi natural anastomosing systems in europe the gearagh ireland is characterized by hundreds of small islands separated by interconnected channels of low slope these include channels that cross islands at right angles to the main flow and blind anabranching channels islands are relatively stable and wooded with evidence of division by channel erosion and growth by in channel sedimentation four active zone cross profiles were surveyed each containing between seven and 13 channels velocities were measured in several channels before and during two separate floods from these observations channels have been categorised into three types fast shallow and trapezoidal slow deep and more irregular and flood channels during the floods interchannel flows were caused by variations in water surface elevations due to backing up behind debris dams and it is suggested that this is the origin of the anomalous cross island channels and one cause of island division another potential cause of island division blind anabranching channels is the result of concentrated bank scour between root masses biotic components such as debris dams tree root masses and tree throw pits play a key role in the partitioning of flow and cause variations in channel velocities and the overbank velocity distribution the implications of these observations for channel pattern maintenance are briefly discussed

thorium uranium disequilibrium dating of late quaternary ferruginous concretions and rinds radioactive ferruginous nodules from the alligator rivers uranium province northern territory australia were systematically examined by optical microscopy xrd alpha and fission track autoradiography and analysed for u th ra and major stable elements correlation of autoradiographs with microscopic structure and analyses of selective extractions confirmed that u and th were strongly associated with fe oxides fission track autoradiography showed no concentration gradient evidence for postdepositional leaching of uranium strong acid leaching studies showed that irreversibly adsorbed u and authigenic 234u and 230th but not 226ra are quantitatively retained by accumulated oxide oxyhydroxide correlation of the groundwater activity ratio with oxidic 234u 238u activity ratios indicated the latter was radiogenically consistent with oxidic 230th 234u activity ratios 1 dense accumulated fe mn oxide matrices are apparently capable of forming radiogenic closed systems in respect of the 230u 234u 230th decay set 234u 238u and 230th 234u activity ratios were used to derive similar mean ages of rinds for four nodules in the same horizon th u ages were also determined using a th index detrital correction method previously used for impure carbonates of pedogenic fe mn accumulations having background concentrations of u and th from other locations in australia these ages were compared with tl and 14c ages of the host sediments the comparisions suggest that th u dating could be used to age indurated layers of fe mn oxides in soil horizons 350 ka old

early diagenesis of organic matter rich sediments in a ria environment organic matter sources pyrites morphology and limitation of pyritization at depth abstract the subtidal sediments of the inner ria de vigo nw spain are fine grained rich in organic matter and accumulate at rates of around 3 mm yr redoxomorphic pyrites formation was studied in four sediment cores four operationally defined iron fractions were determined hcl extracted silicate bound organic and pyritic and the dimensions and morphology of pyrites which mainly occurred as isolated framboids 3 5 m in diameter were studied by sem sediment appearance and degree of pyritization dop identified an oxic zone limited to the top few millimetres a suboxic zone that in most cores was just a few decimetres thick the exception was a core obtained in an area of strong turbulent currents and an underlying anoxic zone with dop values of around 60 pyritic iron increased at the expense of the hcl extracted fraction in approximately the top metre but no further pyrite formation occurred at greater depths pyrite formation in these lower levels was not limited by lack of either hcl extracted iron or metabolizable organic matter but apparently by lack of sulphate ion the diffusion of which to these depths was probably prevented by the fine texture of the sediments our findings highlight the interest of studying transitional sedimentary environments in order to explore in detail the geochemical parameters controlling pyrite formation

thermal conductivity of water saturated rocks from the ktb pilot hole at temperatures of 25 to 300 c the conductivitites of selected gneiss two and amphibolite one core samples have been measured under conditions of elevated temperature and pressure with a needle probe water saturated thermal conductivity measurements spanning temperatures from 25 to 300 c and hydrostatic pressures of 0 1 and 34 mpa confirm the general decrease in conductivity with increasing temperature but deviate significantly from results reported from measurements on dry samples over the same temperature range the thermal conductivity of water saturated amphibolite decreases with temperature at a rate approximately 40 less than the rate for dry amphibolite and the conductivity of water saturated gneiss decreases at a rate approximately 20 less than the rate for dry gneiss the available evidence points to thermal cracking as the primary cause of the more rapid decrease in dry thermal conductivity with temperature the effects of thermal cracking were also observed in the water saturated samples but resulted in a net decrease in room temperature conductivity of less than 3 these results highlight the importance of duplicating in situ conditions when determining thermal conductivity for the deep crust

palaeoenvironmental reconstruction of the cardak coal seam sw turkey abstract the study focuses on the firstly documented cardak coal seam cored in the neogene acigol basin denizli province being formed in a late stage of alpine orogeny in sw turkey the aim is to contribute reconstructing the palaeoenvironmental conditions before during and after coal formation on the basis of coal petrology mineralogical and palaeontological data combined with the results of previous studies the basin infilling consists of alluvial fluvial and lacustrine sediments their deposition depended on the water level in the basin which in turn was controlled by the interplay between tectonics and climate coal seam was probably formed in latest miocene early pliocene under the influence of basin s fluvial regime in oxbow and terminal lakes the coal seam comprises alternating inorganic and coal layers logged between depths of 599 00 to 627 00 m beneath surface the coal being lignite to subbituminous in rank displays moderate to high ash yield 21 31 46 11 wt on dry basis and high total sulphur content up to 13 30 wt on dry ash free basis the maceral composition points to an origin from mainly herbaceous helophytes along with woody species in the upper part of the core the presence of salinity tolerant ostracod species along with gypsum and halite are documented the palaeontological and mineralogical data obtained imply changes of climate water level and lake chemistry in the basin

the origin of terrestrial heat flow summary a theory of the origin of the earth s heat which agrees with all observations is presented the radiogenic heat production from the decay of u and th was computed from their abundances in ordinary chondrites from which the earth accreted and from the abundance of potassium in the mantle plus crust the total radiogenic heat production is 1 14 1013 w because u and th are incompatible in the silicates they have migrated upward into the continental rocks the sediments eroded from the continents are returned to the continents on subducting oceanic slabs therefore about 90 per cent of u and th are concentrated in the continents this is confirmed by a worldwide survey of helium in the oceans which found only 5 per cent of the helium that should have been there had the heat come from radioactive decay subtracting the radiogenic heat production of 1 14 1013 w from the total heat loss of 4 2x1013 w yields 3 06 1013 w to be supplied by the non radioactive sources in the mantle it is proposed that non radiogenic heat originates from secular cooling and from the release of gravitational potential energy by the absorption of feo from the mantle into the core this reaction has been produced in the laser heated diamond anvil cell at temperatures and pressures of the core mantle boundary layer as the molten iron extracts most of the feo out of the perovskite of the mantle a light residue consisting of an iron depleted perovskite and stishovite a form of silica rises in the form of plumes and megaliths generating heat by viscous friction if the oxygen now present in the core got there by this process 1027 g of feo have descended into the core generating energy at an average rate of twice the present rate of loss of non radiogenic heat adding the contribution of secular cooling an average rate of non radiogenic heat production of 1014 w could have been sustained for the last 4 6 billion yr

selective crystallization and precipitation of authigenic pyrite during diagenesis in uranium reservoir sandbodies in ordos basin abstract the occurrence characteristics of authigenic pyrite during diagenesis in uranium reservoir sandbodies of zhiluo formation in ordos basin are investigated based on outcrop area investigations and drilled cores observations the pyrite is closely related to carbonaceous debris microscopically the host components for pyrite consist of carbonaceous debris clay minerals biotite the earlier pyrite and ilmenite by emphasizing on 34s values via la icp ms as well as observing through optical microscope and scanning electron microscope equipped with energy dispersive spectroscope three kinds of distribution pattern of pyrite are classified as i periphery ii infilling iii the combined form of the above two in situ micrometer scale sulfur isotope analyses of pyrite demonstrated that broad scale isotopes are heterogeneous from 52 5 to 35 4 of 34s and sulfur is derived from more than a single source significant differences of host components effects on authigenic pyrite formation are discussed the carbonaceous debris can supply the energy for the bacterial sulfate reduction process and the biotite can provide the source of iron for pyrite precipitation the ferrous ion can be adsorbed on the surface of the clay minerals meanwhile the authigenic pyrite is distributed in or around the earlier pyrite and ilmenite by the indirect adsorption of ferrous ion and the ilmenite may also provide the source of iron futhermore the uranium minerals are mainly associated with the authigenic pyrite relevant to carbonaceous debris and clay minerals which indicates there exists constraints of authigenic pyrite during diagenesis on the uranium mineralization

thermoluminescence dating study of quartz in aeolian sediments from southeastern australia abstract using 90 125 m grains of quartz extracted from sediments the equivalent dose absorbed since burial was derived by exposing aliquots of quartz to a sunlamp regenerating the tl growth curve by artificial irradiation and comparing the natural tl of the sample being dated as well as that of an adjacent surface sample to this curve the age can then be calculated once the dose rate is known the method is tested successfully on known age aeolian sediments retaining their original bedding but reveals some difficulties in trying to use tl to date aeolian sediments for which the original bedding has been destroyed anomalous fading of tl in quartz is reported this latter difficulty was circumvented by using a delay of several weeks between the irradiation and heating of the quartz

comparative uranium thorium and thermoluminescence dating of weathered quaternary alluvium in the tropics of northern australia abstract thermoluminescence tl age determinations of alluvial sediments in the tropics are evaluated by comparison with u th age determinations of pedogenic accumulations in the alluvium of the lower gilbert river a large fan delta in the wet dry tropics of northern queensland australia this study extends u th dating by applying it not only to calcretes but also to fe mn oxyhydroxide oxide accumulations while a direct correlation cannot be made between u th dates from secondary minerals and tl dates from the host sediments both sets of data show broad consistency in addition to providing a minima for acceptable tl ages u th dates are useful for determining the chronology of pedogenesis diagenesis they show that calcretes and ferricretes have formed under similar climatic conditions in the wet dry tropics of northern australia during the late pleistocene beneath about 5 12 m the gilbert fan delta consists of an extensive sand body older than 85 000 yr and probably about 120 000 yr in age representative of a period of major fluvial activity not repeated since this time above are muds and fine sandy muds that extend uninterrupted to the present surface except in the downstream fan where they are bisected by a thin unit of medium sand that tl dates at 40 000 50 000 yr b p a system of sandy distributary channels over the fan surface represents an early holocene fluvial phase probably more active than at present

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

mineralogy and geochemistry of the palaeogene low rank coal from the baise coalfield guangxi province china abstract some previous studies have investigated the enrichment origin of sb and cs in coal but strong supportive evidence for the sources of the two elements in coal is still absent the main aims of this study were to provide a better understanding of the geochemical and mineralogical characteristics of the palaeogene no 5 coal from the zhoujing coal mine baise coalfield guangxi province southwestern china the no 5 coal has a low rank 0 44 ro max 46 96 volatile matter content an average ash yield 19 37 and a medium sulfur content 1 23 on average the main minerals in the no 5 coal are kaolinite illite quartz and pyrite bassanite 2caso4 h2o was identified in the low temperature ashes in varying proportions 2 7 37 6 the mineralogy of the non coal samples partings roof and floor strata is similar to that of the coals but chlorite is additionally present and pyrite is largely absent in these non coal samples the modes of calcite occurrence in the partings indicates a terrigenous origin for this phase compared with average values for world low rank coals the no 5 coal is distinctively enriched in sb 29 12 g g cs 9 71 g g and u 15 61 g g compared with the average values for world clays the parting and host rock samples have normal concentrations for most trace elements with an exception of higher sb 9 93 g g the elevated sb and cs in the coal were derived from the detrital material shedding from the exposed middle triassic strata which host notable au and sb deposits in the surrounding region the rey rare earth elements and y distribution patterns for the coal benches partings roof and floor strata are generally characterized by enrichment in medium rey and positive gd anomalies both of which were due to acidic waters circulating within the coal basin the mineral compositions and their association indicate that the depositional environment was weakly acidic at the early stage of peat accumulation and then changed to neutral or weakly alkaline in the later stage

radiogenic heat production in the lithosphere of sulu ultrahigh pressure metamorphic belt abstract the chinese continental scientific drilling ccsd project is located at the sulu ultrahigh pressure metamorphic uhpm belt it offers a unique opportunity for studying the radiogenic heat production of both shallower and deeper rocks based on the concentrations of radiogenic elements u th and k on 349 samples from main hole of ccsd ccsd mh pilot holes and exposures we determined radiogenic heat productions of all major rock types in the sulu uhpm belt results show the mean values of orthogneiss and paragneiss are respectively 1 65 0 81 and 1 24 0 61 w m 3 due to different composition and grade of retrogressive metamorphism the eclogites display significant scatter in radiogenic heat production ranging from 0 01 to 2 85 w m 3 with a mean of 0 44 0 55 w m 3 the radiogenic heat production in ultramafic rocks also varies within a large range of 0 02 to 1 76 w m 3 and the average turns out to be 0 18 0 31 w m 3 based on the measurements and crustal petrologic model the vertical distribution model of heat production in sulu crust is established the resulting mean heat production 0 76 w m 3 contributes 24 mw m 2 to the surface heat flow 1 d thermal model indicates that the temperature at the moho reaches above 750 c and the thermal thickness of the lithosphere is 75 km in good agreement with the geophysical results the high teat flow 75 mw m 2 together with thin lithosphere presents strong support for the extension events during the late cretaceous and cenozoic

volcanism sedimentation and massive sulfide mineralization in a late cretaceous arc related basin eastern taurides turkey abstract late cretaceous arc volcanism and associated massive sulfide mineralizations occur in the eastern taurus mountains the mineralizations are related to felsic dacitic rhyolitic volcanic rocks which together with basement rocks form the lowermost levels of a 5000 m thick volcano sedimentary sequence and are restricted to a few levels within the sequence basaltic rocks which are intruded by tonalite and dacite form the base of the volcano sedimentary sequence the dacitic rhyolitic rocks are overlain by a volcano sedimentary succession with andesitic dacitic flows the flows do not contain any mineralization this succession starts with volcanic breccia and tuffs at the base passing into crystal rich sandstone and pelagic mudstone with tuffite intercalations and ends with marls intercalated with sandstones basalt and peridotite olistoliths the felsic rocks bear stockwork and disseminated types of mineralization the massive sulfide mineralization has a simple mineral assemblage of pyrite chalcopyrite bornite and sphalerite optical microscopic examination of pyrites from derince massive sulfide deposits reveals that the pyrites are commonly seen in framboidal and cubic forms the geochemistry of the magmatic rocks and sedimentary facies associations indicate that the mineralizations in the derince were developed in an intra arc environment

optical dating of sediments a new method for dating sediments is proposed which determines the time since the sediment was last exposed to sunlight an argon ion laser is used to excite electrons from thermally stable light sensitive traps and the subsequent luminescence used as a measure of the past radiation dose two sample sequences spanning the periods 0 700 kyr and 0 6 kyr show steadily increasing luminescence with age an age of 62 8 kyr is obtained for a silt radiocarbon dated at 58 8 0 3 kyr problems were found with two much younger samples

three dimensional interpretation of the ktb gravity and magnetic anomalies a combination of a closely spaced surface gravity survey with a high resolution helicopter aeromagnetic survey as well as borehole gravity and magnetometer measurements allowed a detailed three dimensional 3 d modeling of the anomalies at the ktb drill site the models could be constrained by new evidence from a 3 d seismic survey and by structural geology and petrophysical data from drill cores and cuttings the source body for the positive gravity anomaly consist of high density metabasite the vertical derivative of the bouguer anomaly does not resemble the aeromagnetic anomaly in all areas indicating that parts of the metabasites are more or less nonmagnetic surprisingly and confirming the observation in other deep drill holes into continental crystalline basement rocks pyrrhotite is the dominant magnetic mineral below a depth of about 300 m magnetite mainly occurs in the depth intervals 360 520 m and 7300 7900 m the lower interval causes the anomalous vertical gradient of 60 nt km for the geomagnetic field the occurrence of strongly magnetic minerals in the borehole down to about 3000 m correlates with the lithology while in the deeper parts it is more related to fissures and fault zones where chemical processes reduction oxidation are active

organic matter provenance and depositional environment of marine to continental mudstones and coals in eastern ordos basin china evidence from molecular geochemistry and petrology abstract cyclothems composed of interbedded mudstone coal and sandstone layers make up the taiyuan and shanxi formations in the late carboniferous to early permian in north china under a marine to continental depositional environment the cyclothems act as important fossil energy hosts such as coalbeds hydrocarbon source rocks and unconventional natural gas reservoirs organic geochemistry and petrology of mudstones and coals in the taiyuan and shanxi formations in the eastern ordos basin were studied to reveal the organic matter sources and paleoenvironments total organic carbon toc contents vary from 1 1 wt mudstone to 72 6 wt coal the samples are mainly within the oil window with the tmax values ranging from 433 to 469 c organic petrology and source biomarkers indicate that the mudstones were sourced from a mixed organic matter input and terrigenous organic matter predominates over aquatic organic matter the coals are mostly sourced by terrigenous organic matter inputs high concentrations of hopanes argue for a strong bacterial input some m z 217 mass chromatograms have peaks at the hopanes retention times as a result of high hopane to sterane ratios these hopane derived peaks do not interfere the identification of the steranes because the hopanes and the steranes have different retention times maturity dependent biomarkers demonstrate that the samples have been thermally mature which agree with the tmax values anomalously low c29 20s 20s 20r and c29 sterane ratios are present in all the samples and are interpreted as due to the terrigenous organic matter input or the coal related depositional environment in addition biomarkers and iron sulfide morphology indicate that the organic matter of the mudstones deposited in a proximal setting with shallow brackish fresh water bodies with consideration of preservation of organic matter the redox conditions are dysoxic redox oscillations resulted in the records of oxic conditions in some samples finally the coals and the mudstones mainly generate gas and have poor oil generative potential