fluid inclusion and vitrinite reflectance geothermometry compared to heat flow models of maximum paleotemperature next to dikes western onshore gippsland basin australia abstract nine basalt dikes ranging from 6 cm to 40 m thick intruding the upper jurassic lower cretaceous strzelecki group western onshore gippsland basin were used to study maximum temperatures t max reached next to dikes t max was estimated from fluid inclusion and vitrinite reflectance geothermometry and compared to temperatures calculated using heat flow models of contact metamorphism thermal history reconstruction suggests that at the time of dike intrusion the host rock was at a temperature of 100 135 c fracture bound fluid inclusions in the host rocks next to thin dikes t max systematically increases towards the dike margin to at least 500 c the estimated t max next to the thickest dike thickness d 40 m suggests an extended zone of elevated r v r to at least a distance from the dike contact x of 60 m or at x d 1 5 using a normalized distance ratio used for comparing measurements between dikes regardless of their thickness in contrast the pattern seen next to the thin dikes is a relatively narrow zone of elevated r v r heat flow modeling along with whole rock elemental and isotopic data suggests that the extended zone of elevated r v r is caused by a convection cell with local recharge of the hydrothermal fluids the narrow zone of elevated r v r found next to thin dikes is attributed to the rise of the less dense heated fluids at the dike contact causing a flow of cooler groundwater towards the dike and thereby limiting its heating effects the lack of extended heating effects suggests that next to thin dikes an incipient convection system may form in which the heated fluid starts to travel upward along the dike but cooling occurs before a complete convection cell can form close to the dike contact at x d r v r often decreases even though fluid inclusion evidence indicates that t max is still increasing further fluid inclusion evidence indicates that the evolution of water vapor or supercritical fluids in the rock pores corresponds to the zone where r v r begins to decrease the generation of the water vapor or supercritical fluids near the dike contact seems to change vitrinite evolution reactions these metamorphic conditions closer to the dike than x d 0 3 make vitrinite reflectance unreliable as a geothermometer the form of the r v r profile as it indicates t max can be interpreted using temperature profiles estimated from various heat flow models to infer whether the dike cooled by conduction incipient convection or a convection cell a contact aureole that consists of decreasing r v r or t max extending out to x d 2 and that has a t contact t magma t host 2 appears to be a signature of simple conductive cooling incipient convection is indicated by a r v r profile that decreases to background levels at x d r v r profile and consistently high r v r that may not decrease to background levels until beyond distances of x d 1 5

chemical weathering indices applied to weathering profiles developed on heterogeneous felsic metamorphic parent rocks abstract chemical weathering indices are commonly used for characterizing weathering profiles by incorporating bulk major element oxide chemistry into a single metric for each sample generally on homogeneous parent rocks weathering indices change systematically with depth however the weathering of heterogeneous metamorphic rocks confounds the relationship between weathering index and depth in this paper we evaluate previously defined chemical weathering indices for their suitability in characterizing weathering profiles developed on felsic heterogeneous metasedimentary bedrock from coweeta hydrologic laboratory north carolina usa among the weathering indices evaluated here the weathering index of parker wip is the most appropriate for application to weathering profiles on heterogeneous and homogeneous parent rock because the wip includes only the highly mobile alkali and alkaline earth elements in its formulation it yields values that differ greatly from those of the parent rock in addition the wip allows for aluminum mobility unlike other weathering indices these characteristics combine to make the weathering index of parker the most applicable index for studying the weathering of heterogeneous metasedimentary rocks however the wip should be applied judiciously as alkali and alkaline earth metals may be readily depleted during weathering in addition to reflecting weathering the chemical index of alteration cia chemical index of weathering ciw plagioclase index of alteration pia and vogt s residual index v may be sensitive to subtle geochemical changes such as hydrothermal alteration along a fault and or alteration at the water table weathering indices that include iron in their calculations were not included in this study because they do not distinguish between ferric and ferrous iron the oxidation state and distribution of iron in a weathering profile is influenced by the proportion of oxidation states in the pre weathered metamorphic rock and interaction with groundwater during weathering

geochemistry and origin of the ore chimney formation a transported paleoregolith in the grenville province of southeastern ontario canada the ore chimney formation is a mid proterozoic metapelitic rock unit that separates mafic to intermediate metavolcanic rocks of the grenville supergroup from an overlying clastic metasedimentary succession the flinton group it has been interpreted alternatively as a paleoregolith or a product of hydrothermal alteration of the volcanic rocks in a major shear zone the formation is thin 10 m massive to poorly layered crops out over 40 km along strike and is typically composed of alternating layers of biotite schist muscovite biotite schist hornblende biotite schist and hornblende schist it typically contains coarse porphyroblasts of garnet and less commonly of staurolite kyanite epidote and or hornblende thirty five samples of the ore chimney formation fifty samples of the underlying metavolcanics and fourteen samples of the overlying clastic metasediments were analysed for major and twenty eight trace elements including ree immobile trace element ratios ti zr zr y nb y la yb indicate that the ore chimney formation is locally derived from the underlying metavolcanics bulk chemistry field relations and petrographic observations strongly suggest that the ore chimney formation is a locally reworked weathering product of the metavolcanic rocks

carbon isotope analysis of whole coal and vitrinite from intruded coals from the illinois basin no isotopic evidence for thermogenic methane generation abstract igneous intrusions into coals and organic rich rocks may have contributed to global warming in the geologic past through the release of greenhouse gases evidence for a large release of thermogenic ch4 from the organics would include significant 13corg enrichment in the residual organic matter om however 13corg values of thermally altered om in coals and shales adjacent to intrusions often show negative trends or in some cases ambiguous or positive trends previous studies have evaluated the 13corg of whole coal samples rather than that of individual organic components or macerals as different macerals have different isotopic compositions maceral specific trends may be masked by variations in maceral composition of the bulk samples this study evaluates the hypothesis that if a large scale release of 13c depleted thermogenic ch4 resulted from intrusion of the coal then it should have produced 13c enriched coal residuum and specifically vitrinite the most abundant component of the coal adjacent to the intrusion this study reports geochemical and petrographic data for whole coal samples and vitrinite macerals separated via density gradient centrifugation dgc from a transect of thermally altered springfield no 5 coal pennsylvanian in the illinois basin approaching the dike contact mean vitrinite reflectance rr increases from background levels of 0 55 up to 4 8 and liptinites become indistinguishable from vitrinite isotropic and fine grained circular mosaic coke is observed in samples within 1 3 m of the coal intrusion contact approaching the intrusion volatile matter vm decreases and fixed carbon fc and c increase whereas h decreases total organic carbon toc for whole coal decreases from 77 to 34 whereas toc for separated vitrinite fractions increases from 66 to 93 toward the coal intrusion contact density of dgc separated vitrinites ranges from 1 27 g ml in the unaltered coal to 1 52 g ml in the sample adjacent to the coal intrusion contact vitrinite density increases with increased rr and c and decreases with increased h and h c despite these marked geochemical and petrographic changes no significant changes in 13corg values of the whole coal 25 3 to 24 9 or the separated vitrinites 25 3 to 25 0 occur proximal to the intrusion changes in the isotopic signatures are not of a magnitude that would be expected if significant quantities of isotopically depleted thermogenic ch4 had been generated by the intrusive event moreover no petrographic evidence supports the occurrence of condensed or immobilized thermal products due to rapid pyrolysis such as 12c rich pyrolytic carbon close to the intrusion that could have moderated any changes in 13corg geochemical and petrographic results suggest that only minimal loss of ch4 was associated with the rapid heating of the springfield no 5 coal by the intrusion these findings have significant implications for models linking past global warming to the intrusion of coals and carbonaceous shales

temporal change in coda q before the tangshan earthquake of 1976 and the haicheng earthquake of 1975 a new earthquake precursor called coda q is demonstrated for the tangshan earthquake of 1976 and for the haicheng earthquake of 1975 the precursor is based on the measurement of coda decay rate for small local earthquakes in the general area that is preparing for a major earthquake during the 3 year period preceding the tangshan earthquake the coda q was about 3 times lower than it was before or after this period a comparable change also occured at the time of the haicheng earthquake the observed change cannot be due to the change in the source parameters such as the focal depth or the source spectrum the coda q precursor appears to detect the same physical process detected by other precursors such as b value quiescence radon water quality vp vs and animal behavior but has advantages over them in its clearer physical mechanism easier sampling and better defined anomalous region

attenuation of coda waves in new england abstract seismic wave attenuation was measured in new england from the time domain decay of coda wave amplitudes on narrow bandpass filtered seismograms of local earthquakes the frequency band of interest was 0 75 to 10 hz q c f was found to increase with frequency across this band but there was also a difference between the q c f values for short t t 100 sec lapse times of coda wave propagation for the short lapse time data corresponding to wave paths primarily in the upper crust q c f increases from 400 at 3 hz to 1300 at 10 hz for the large lapse time data corresponding to wave paths in the lower crust and upper mantle q c f was found to vary from 660 at 1 hz to 1500 at 10 hz if we interpret this dataset in terms of a model incorporating both scattering and anelastic attenuation we find that the mean free path of seismic waves over this frequency band is 80 km for short lapse times and 400 km for long lapse times if we assume that scattering is entirely responsible for the observed attenuation we find that the minimum mean free path for short lapse times is about 75 km over all frequencies whereas for long lapse times the minimum mean free path decreases from 400 km at 0 75 hz to 90 km at 10 hz

combined oxygen isotope compositional studies of some granitoids from the grenville province of ontario canada implications for source regions oxygen isotopic compositions of whole rocks and coexisting quartz feldspar pairs have been determined for nine pre and syn to late kinematic granitoid plutons in the grenville province of ontario these new data demonstrate that granitoid rocks algonquin mulock in migmatite terrain of the ontario gneiss segment possess normal 18o values 9 0 in accord with previous results in the algonquin sodic suite a gross covariance of 18o with compositional indices is present from 6 4 sio2 50 5 wt gabbro to 8 7 sio2 72 wt trondhjemite resulting from combined assimilation fractional crystallization mafic members of the sodic suite are 18o enriched overall 5 8 7 9 relative to fresh tholeiites 5 7 0 3 implicating some 18o contamination of the protolith the dispersion of 18o values in the

deterioration mechanisms of tuffs in midas monument slightly weathered white and pink tuffs of the midas monument have deterioration problems in this study depths and characteristics of the weathering zones developed within the tuffs are investigated through optical microscopy x ray diffractometry xrd chemical analyses scanning electron microscopy sem and some index parameters accelerated weathering tests including wetting drying freezing thawing and salt crystallization are performed and durability assessment methods are used to predict the durabilities of the tuffs the findings are compared with field observations by examining quantitative weathering indices and comparing them with thin section studies it is found that thin section analyses of the crystals loi and wpi are good indicators to quantify the depth of weathering for the tuffs however thin section studies have limited value for fine grained tuffaceous matrix the chemical weathering of the tuffs produces weathered zones that are 4 5 cm thick within the white tuff and 2 5 cm thick within the pink tuff physical weathering causes scaling of outer layers of the tuffs and fracturing of feldspars along their cleavage planes however variations of the index properties of the tuffs due to weathering are not so significant to quantify the weathering depths in the tuffs among the accelerated weathering tests salt crystallization is found to be the most destructive environmental condition pigeon droppings rich in no3 are found to be the main source of soluble salt at the midas monument the salt transported up by capillary rise due to surface water causes spalling of the tuffs in the capillary zone surface water and salt of any kind in the close vicinity of the monument should be totally eliminated for the purpose of conservation field observations and the durability equations reveal that the white tuff is less durable than the pink tuff wet to dry strength ratio yields a better stone durability assessment among various durability methods used in this study d 2002 elsevier science b v all rights reserved

re assessment of chemical weathering indices case study on pyroclastic rocks of hong kong abstract quantitative and objective characterization of weathered states of rock by means of chemical weathering indices has significant potential in ground investigation practice this paper reviews more than thirty different chemical indices and re assesses their variations along a weathered profile developed over pyroclastic rocks under subtropical conditions chemical weathering indices are principally based on the basic assumption that distributions of chemical elements as well as loss on ignition loi content along the profile are mainly regulated by the degree of weathering however this study clearly demonstrates that the behavior of chemical elements and loi during weathering depend not only on the degree of weathering but also on microenvironmental conditions that control the type and abundance of clay minerals and sesquioxides and thus determine the level of heterogeneity of the profile it is suggested that signatures of chemical weathering should be used to establish a framework for the interpretation of the heterogeneity level and the prediction of variability in engineering properties rather than for quick classifications using chemical weathering indices

comparison of 226ra 238u and 228th 228ra disequilibrium with weathering indices in beach sand sediments from greece weathering indices can be used to quantify weathering of rocks at various stages of weathering processes and provide a better understanding of element mobility during weathering various weathering indices have been proposed in the literature worldwide in the present work radioactive secular disequilibrium has been used to determine weathering extent thirty seven samples from kavala and thirty from sithonia beach sands all of them being the weathering products of the local granitic plutons are studied for their secular disequilibrium in both 238u and 232th series 226ra 238u and 228ra 228th respectively the results are compared to weathering indices already in use worldwide and suggest a consistent correlation with wip alkaline and alkaline earth element leaching and pwi silica leaching for the well and very well sorted sands and for the heavy minerals of kavala this study suggests that with an appropriate choice of the weathering index and samples both u series and weathering index can recover the extent of chemical weathering

mobilities of alkalis alkaline earths and halogens during weathering abstract concentrations of alkali metals alkaline earths and halogens were monitored in an australian weathering profile and in brazilian soils and bauxite the materials analysed are considered to represent a range of chemical weathering histories which are distinguished with respect to their degree of leaching by the dominant aluminosilicate assemblages during initial weathering concentrations of alkalis and alkaline earths are similar or enriched relative to average crustal abundances as weathering proceeds depletion is attenuated by the capacity of a particular element to participate in adsorption and ion exchange processes strong depletion of alkalis and alkaline earths is common as weathering advances and clay minerals are replaced by al oxide phases e g gibbsite with much lower capacities for exchanging and incorporating ions halogen concentration trends are more variable f retention during weathering is likely due to substitution in mineral phases for hydroxyl groups cl and i are commonly observed to accumulate as weathering advances and some of these accumulations may be due to atmospheric additions

post depositional migration of elements during diagenesis in brown clay and turbidite sequences in the north east atlantic abstract two cores from a ne atlantic pelagic clay area of low accumulation rate each contain a single turbidite with different age thickness and composition diagenesis following introduction of exotic turbidite material into the pelagic clay sequence has resulted in distinctive colour changes the diagenetic process is thought to be driven by bacterially mediated organic oxidation and compositional differences in the turbidites and clays allow examination of the effects on metal concentrations of this process in one core a long turbidite section emplaced 330 000 years ago is overlain by clay organic oxidation has apparently proceeded from the turbidite top downwards and has maintained a u concentration peak below the oxidation front marked by a colour change the u source is believed to be u initially associated with the organic matter in the oxidised section of the turbidite vanadium and cu behave similarly but upward migration of the redox sensitive metals mn and ni is also seen in the second core an 8 cm turbidite section was emplaced about 170 000 years ago in a clay column in this case organic consumption now appears complete but evidence for diagenetic effects is found in a 16 cm compositional alteration halo of the underlying pelagic clay fe ii has been enriched and the hydrogenous component of mn co ni and cu removed from the pelagic clay to form the halo

estimates of q in central asia as a function of frequency and depth using the coda of locally recorded earthquakes digital recordings of microearthquake codas from shallow and intermediate depth earthquakes in the hindu kush region of afghanistan were used to determine the attenuation factors of the s wave coda qc and primary s waves q an anomalously rapid decay of the coda shortly after the s wave arrival observed also in a study of coda in central asia by rautian and khalturin 1978 seems to be due primarily to depth dependent variations in qc in particular we deduce the average qc in the crust and uppermost mantle 100 km depth is approximately four times lower than the deeper mantle 400 km depth over a wide frequency range 0 4 to 24 hz further while qc generally increases with frequency at any depth the degree of frequency dependence of qc depends on depth except at the highest frequency studied here 48 hz the magnitude of qc at a particular frequency increases with depth while its frequency dependence decreases for similar depths determinations of q and qc agree suggesting a common wave composition and attenuation mechanism for s waves and codas comparison of these determinations of qc in afghanistan with those in other parts of the world shows that the degree of frequency dependence of qc correlates with the expected regional heterogeneity such a correlation supports the prejudice that qc is primarily influenced by scattering and suggests that tectonic processes such as folding and faulting are instrumental in creating scattering environments

relationships between chemical weathering indices and physical and mechanical properties of decomposed granite abstract chemical weathering is one of the dominant mechanisms for weathering of granite in subtropical and tropical regions resulting in modifications of its chemical physical and mechanical properties thus the changes in chemical properties may provide insight about the changes in physical and mechanical properties of weathered granite in this paper three quantitative chemical weathering indices are correlated to the dry density of decomposed granite a linear relationship is found between each chemical weathering index and dry density for granitic saprolites mobiles index i mob gives the highest coefficient of correlation among the three chemical weathering indices further investigations were conducted to establish the relationships between i mob and other physical and mechanical properties of granitic saprolites the test results showed that fines content increases with increasing i mob but peak strength increases with decreasing i mob the peak states of granitic saprolites are consistent with rowe s stress dilatancy relationship dilatancy increases with decreasing i mob that contributes to a higher peak strength based on some test results presented in this study it seems that i mob could be a good indicator to quantify the effects of chemical weathering on physical and mechanical properties of granitic saprolites

40ar 39ar geochronology of ferrar dolerite sills from the transantarctic mountains antarctica implications for the age and origin of the ferrar magmatic province the ferrar dolerite constitutes the hypabyssal phase of the tholeiitic ferrar group of antarctica sills with compositions representing most of the range of geochemical variation of the ferrar dolerite and separated by distances of as much as 1400 km have been analyzed by the 40 ar 39 ar method on feldspar and biotite separates the 40 ar 39 ar ages for five individual sills range from 176 2 to 177 2 ma and show no significant difference these ages reflect crystallization at 176 7 1 8 ma where the uncertainty includes provision for systematic uncertainty in the age of the neutron fluence monitor calibrated relative to mmhb 1 at 513 5 ma combining data from these sills with previous determinations on coeval lavas and underlying pyroclastic units indicates an age of 176 6 1 8 ma for the ferrar tholeiitic rocks as a whole the duration of magmatic activity was less than approximately 1 m y by extension other rocks in the ferrar magmatic province which occur from southeastern australia along the transantarctic mountains to the theron mountains are inferred to have this age the short duration of magmatic activity as well as the consistent pattern of geochemical variation and distinctiveness of the ferrar rocks suggest that magmas were transported laterally by an extensive dike swarm which is inferred to have originated in the weddell sea sector of the province

metallogeny of structural zones grenville province northeastern north america abstract recent subdivision of the grenville province into northwestern central and southeastern tectonic zones provides a convenient basis for describing the tectonic affiliation of the contained mineral deposits the northwestern zone consists of reworked foreland lithologies southeast of the grenville front major deposits of metamorphosed superior type iron formations are present in metamorphosed kaniapiscau supergroup equivalents exposed at lower metamorphic grades in the labrador trough occurrences of volcanogenic massive sulphides abitibi group equivalents ni cu quartzite hosted u au and alkaline intrusion hosted ree s are of only mineralogical importance the central zone contains polydeformed gneisses that have been intruded by three ages of anorogenic anorthosite massifs circa 1 64 1 36 and 1 14 ga and associated charnockite magnerite complexes major magmatic ti fe lac allard and large low grade ni cu mcnickel deposits are associated with the younger anorthosite suite magmatic ni cu also occurs in differentiated metapyroxenite metaperidotite of uncertain age pegmatites are widespread but not commercially important the southeastern zone consists of the rocks of the central metasedimentary belt cmb and central granulite terrane cgt as well as rocks of the relatively unmetamorphosed wakeham supergroup initial deposition of volcanic and carbonate rocks occurred in the cmb between 1 28 and 1 24 ga and was followed by deposition of the flinton group 1 15 ga the rocks are overprinted by the elzeviran and ottawan orogenies 1 25 and 1 08 ga respectively volcanogenic zn pb ag au deposits and sedex marble hosted zn deposits occur widely in the layered rocks of the central metasedimentary belt deposition 1 28 ga small massive sulphide and shale hosted base metal occurrences and both oxide and sulphide iron formations are widespread near volcanic lithologies but are generally small or very low grade syngenetic magmatic deposits include subeconomic fe ti and ni cu deposits that are syntectonic with respect to the ottawan orogeny but others may be as old as elzeviran small magnetite rich skarn deposits are widespread with 2 major past producing deposits and are related to magmatic events accompanying the elzeviran orogeny gold and gold sulphosalt occurrences in grenville volcanic and carbonate lithologies and flinton group rocks of various types are not well constrained in age some are spatially associated with older elzeviran intrusions and have been genetically related to them others exhibit metamorphic textures but cut younger flinton group rocks while others appear to be completely post metamorphic extensive pegmatitic and related skarn and carbonate vein u mo ree occurrences may relate either to metamorphic or intrusive processes related to the ottawan orogeny in the cgt fe ti and ni cu occurrences associated with the younger anorogenic anorthosite massifs are similar to occurrences in the central zone large fluorite bearing magnetite iron deposits associated with alaskitic gneisses are interpreted as similar to the swedish kiruna type deposits following stabilization of the grenville craton rifting associated with the opening of iapetus in the latest proterozoic cambrian and again in the cretaceous resulted in the regional intrusion of alkaline complexes which included large nb and ree rich carbonatite intrusions in the cretaceous rift related faults became the sites of small fluorite barite galenastrontianite deposits over a wide area in the elzevir and frontenac terranes and in the charlevoix saguenay area of the central zone

petrogenesis of the elzevir batholith and related trondhjemitic intrusions in the grenville province of eastern ontario canada the elzevir batholith belongs to a suite of trondhjemitic intrusions emplaced at ca 1 240 ma in the grenville province of eastern ontario new major and trace element data including ree combined with isotopic and petrographic data indicate that 1 the batholith has calc alkalic affinities 2 the elzevir parental magma is very similar to that of dacites in the nearby coeval metavolcanic rocks the magma formed by partial melting of crustal material at granulite grade 3 chemical differences between the plutonic and volcanic rocks can be best explained by accumulation of plagioclase in the plutonic environment 4 fractionation was dominated by plagioclase and quartz with lesser biotite and epidote and minor zircon and apatite

quantification of weathering depths in slightly weathered tuffs slightly weathered white and pink tuffs of midas monument have deterioration problems in this study depths of the weathering zones developed in the tuffs are investigated through optical microscopy xrd chemical analyses sem and some index parameters by examining quantitative weathering indices and comparing them with thin section studies it is found that thin section analyses of the phenocrysts loi and wpi are good indicators to quantify the depth of weathering for the tuffs however thin section studies have limited value for fine grained tuffaceous matrix the chemical weathering of the tuffs produces weathered zones that are 4 5 cm thick within the white tuff and 2 5 cm thick within the pink tuff physical weathering causes fracturing of feldspars along their cleavage planes variations of the index properties of the tuffs caused by weathering are not significant enough to quantify the weathering depths in the tuffs

detailed attenuation study of shear waves in the kumaon himalaya india using the inversion of strong motion data abstract the frequency dependent shear wave quality factor q f of the seismically active kumaon himalaya was calculated using strong motion data recorded between 2006 and 2012 the inversion algorithm of strong motion data developed here simultaneously gives the shear wave quality factor and the site effect for each earthquake the site effects obtained from the present inversion are within the standard limit of error and agree with those obtained through the h v technique h v being the ratio of the fourier spectra of the horizontal and vertical components of the record the q f values in which q is shear wave quality factor and f is frequency at different stations were computed using both the north south and east west components of acceleration records the q f values obtained from both components at 16 stations in the kumaon himalaya were used to compute a regional q f relationship having the form q f 28 2 0 f 1 2 0 07 this q f relationship suggests a low q 0 value n value 0 8 for tectonically and seismically active regions

effect of weathering on the geomechanical properties of andesite ankara turkey andesite exposed in different parts of ankara has different weathering categories varying from fresh to residual soil the geomechanical properties of the andesite are significantly affected by weathering buildings constructed especially in completely weathered and residual soil levels of the andesite have some geotechnical problems in this study the variation of the geomechanical properties of the andesite due to weathering is investigated in three selected sites of ankara through optical microscope x ray diffraction analyses major element analyses pressuremeter tests physicomechanical tests and seismic refraction method the data gathered from the field and laboratory studies were used to assess the characteristics of the weathering zones based on the data obtained from this study an idealized weathering profile is assessed no bearing capacity and consolidation settlement problems exist in the area however care should be taken for immediate settlement of the buildings slopes with heights less than 8 m are not expected to cause any significant problems for buildings there exists a ground amplification problem in the study area the natural period of the building should not match that of the weathered rock the ground response analyses reveal that the buildings with four to seven stories may be adversely affected from earthquakes due to resonance phenomenon therefore this has to be taken into account when designing new buildings

co2 storage potential of south african coals and gas entrapment enhancement due to igneous intrusions abstract methane outburst events have occurred in some underground coal mines of south africa such as those in twistdraai mine in the highveld coalfield in the early 1990s occurrences of methane outbursts suggest that high gas content in adsorbed and free phase might be present in some sections of the coal seams coal seams might also be friable in those sections allowing pulverisation during outburst the survey of gas outburst events indicates that the locations of high gas emissions were mainly in the vicinity of the igneous intrusions mainly dolerite intrusions these intrusions are a result of post depositional volcanism into coal seams in some major coalfields of south africa such as the highveld coalfield this study was undertaken firstly to investigate potential locations for the occurrence of coal seam gas in south african coal seams with respect to the igneous intrusions and their enhancement effect on gas release and storage of these coals secondly it was thought that as the metamorphosed coals with high ash content were not economically viable for mining they might be potentially suitable for co 2 disposal measurements on 14 coal samples taken in an underground coal mine at various distances from a dolerite dyke show that the adsorption and porosity properties of metamorphosed coals have been enhanced thus increasing their gas storage capacity diffusivity results show that dolerite intrusions would act as enclosures and gas traps for storage of gas gas diffusivity was greater in coals near the dyke by a factor of two in general it is expected that the co 2 storage and gas flow properties of such coals be enhanced due to the heating effect of intrusions making the coals more appealing for possible future sequestration of co 2 from anthropogenic sources

the attenuation mechanism of s waves in the source zone of the 1999 chamoli earthquake a partial support has been given by italy ingv dpc istituto nazionale di geofisica e vulcanologia and dipartimento di protezione civile projects unrest and speed and by italy s ministry of education prin project seismic hazard in central apennines ur del pezzo

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

anatomy of an intruded coal i effect of contact metamorphism on whole coal geochemistry springfield no 5 pennsylvanian coal illinois basin abstract if time and heating rate are important agents in coal maturation one might expect to see differences in chemical changes in response to maturation depending on the means of increased rank using a suite of samples obtained from an intruded pennsylvanian age coal in southern illinois we present whole coal chemical data comparing these data to extant geochemical data for coals that have undergone normal burial maturation we evaluated the hypothesis that if coal alteration occurs rapidly due to intrusion rather than gradually burial maturation then different relationships are seen in chemical composition proximate and ultimate analyses and vitrinite reflectance the pennsylvanian age asturian westphalian d springfield no 5 coal is mined at the big ridge mine near eldorado southern illinois this high volatile b bituminous coal was intruded by an ultramafic igneous intrusion during the early permian alteration occurs out to 1 2 dike thickness and includes an increase in random vitrinite reflectance rm from levels 0 7 to over 5 3 loss of liptinites and formation of devolatilization vacuoles and fine mosaic texture decreases in volatile matter vm and increases in fixed carbon fc appear to be less than would be expected for the level of reflectance seen within the alteration halo carbonate minerals have a major influence on proximate analyses but even following the removal of carbonates the decrease in vm is still less than would be seen in coals of similar vitrinite reflectance that were altered by normal burial maturation carbonate mineralization also contributes to variability in ultimate analysis values approaching the intrusion particularly for c and o after carbonate removal data for these coals do not appear to follow the normal burial coalification tracks when plotted on a van krevelen diagram and on a seyler chart these differences suggest that a slightly different maturation pathway may have been followed by these coals and by others that were altered rapidly by intrusion

the behaviour of so called immobile elements in hydrothermally altered rocks associated with volcanogenic submarine exhalative ore deposits evidence is available that some elements notably zr tio2 y sc ce and nb are largely immobile during the alteration of volcanic rocks owing to metamorphism hydrothermal events and weathering e g floyd and winchester 1978 however it is shown by reference to analyses of rocks from the environment of five volcanogenic massive sulphide bodies that while zr tio2 and ce are mostly immobile even during intense hydrothermal alteration y and particularly sc and nb may be extremely mobile when elements are removed by solution in a hydrothermal fluid it seems that reaction rates are such that these elements are almost totally removed from the rock therefore of the so called immobile trace elements only zr and tio2 may be used with any reliability to identify the degree of magmatic differentiation in an hydrothermally altered rock however if an element has been mobile it is usually readily identified as having moved

the abnormal condition analysis used to characterize weathered discard coals coal by its nature is unstable and weathers when exposed to moisture and oxygen weathering can result in a general decline on the commercial value and technological properties of coal coals of similar chemical properties have been shown to combust differently and the differences can be attributed to petrographic composition variations poor combustion environments and weathered particles stockpiled and dumped discard coals have been targeted for use by a lower power utility and a novel technique was developed to quantify and qualify the degree of weathering in these coals the petrographic based abnormal condition analysis previously referred to as the weathering index analysis considers features not typically characterized during routine petrographic analyses but which may have an impact on the technological properties of coals discard coals ranging in age from 5 to 40 years where characterized to determine the extent of secondary weathering eight secondary weathering features clearly different from inherent weathering were qualified and quantified margin effect appears to be an early microscopic indicator of weathering followed by discoloration alteration minerals have only been observed in stockpiled and dumped coals and hence could be a useful feature to benchmark when considering whether or not a coal has been stored long term stored coals have microcrack and fissure patterns clearly different from fresh coals the length of exposure to weathering processes was determined to be proportional to the extent of weathering as determined petrographically the abnormal condition analysis should be used as a supplement to routine coal petrography as it can assist with the determination of anomalous behavior of coals

inorganic chemistry petrography and palaeobotany of permian coals in the prince charles mountains east antarctica sampled outcrops of permian coal seams of the bainmedart coal measures in the lambert graben eastern antarctica have been analysed for their proximates ultimates ash constituents and trace elements a similar series of samples has been analysed for their principle maceral and microlithotype components and vitrinite reflectance the coals are sub bituminous to high volatile bituminous in rank maturity increases markedly in southern exposures around radok lake where the oldest part of the succession is exposed and some strata have been intruded by mafic dykes and ultramafic sills the coal ash is mostly silica and aluminium oxides indicating that the mineral ash component is mostly quartz and various clay minerals the ratio of silica to aluminium oxides appears to increase in an upward stratigraphic direction the coal macerals include a relatively high liptinite content mainly sporinite that is significantly higher than for typical gondwana coals greater degrees of weathering within the floodbasin peat mire environments associated with climatic drying towards the end of the permian might account for both preferential sporopollenin preservation and increased silica aluminium oxide ratios up section correlation of the coal maceral components to adjacent peninsula india coals indicates the closest comparative coals of similar age and rank occur within the godavari basin rather then the mahanadi basin which is traditionally interpreted to have been contiguous with the lambert graben before gondwanan breakup the petrological characteristics suggest that either previous interpretations of palaeozoic basin alignments between antarctica and india are incorrect or that environmental settings and post permian burial histories of these basins were strongly independent of their tectonic juxtaposition a permineralized peat bed within the succession reveals that the coals predominantly comprise wood and leaf rich debris derived from low diversity forest mire communities dominated by glossopterid and noeggerathiopsid gymnosperms

heat flow and structure of the lithosphere in the eastern canadian shield twenty two new determinations of heat flow and radiogenic heat production in the superior and grenville provinces of the canadian shield are presented the new data and previously published measurements strongly constrain the thermal structure of the eastern canadian shield in the abitibi greenstone belt heat flow gradually increases from 29 mw m 2 near the grenville front to 44 mw m 2 east of the kapuskasing uplift this heat flow variation is interpreted in terms of crustal thickening and increased thickness of a tonalitic layer with average heat production of about 1 1 w m 3 this interpretation based on estimated heat production of major rock types in the region is consistent with crustal models derived from recent seismic reflection and refraction studies it also leads to an estimate of about 12 mw m 2 for the mantle heat flow beneath the area the average heat flow in the grenville province 41 10 mw m 2 is the same as that of the superior province this similarity and the lack of significant variation of heat flow across the grenville front indicate that the crust on both sides of the front has similar heat production and thus composition in the western part of the grenville province heat flow reaches high values in the vicinity of the boundary between the allochtonous polycyclic and monocyclic belts where enriched granitic plutons are found in the crystalline terranes in the central part of the grenville province heat flow and heat production are related to each other the parameters of the linear heat flow heat production relationship qr 30 2 in mw m 2 and d 7 1 1 7 km are close to those of the much younger appalachian province implying that the higher appalachian heat flow is due solely to higher heat production in the upper crust the data provide no evidence for variation of mantle heat flow between the superior grenville and appalachian provinces whose tectonic ages range between 2700 and 400 ma the small value of the mantle heat flow about 12 mw m 2 implies that the depth to the 450 c isotherm which controls the effective elastic thickness of the lithosphere is very sensitive to crustal heat production

evidence of rapid cenozoic uplift of the shoulder escarpment of the cenozoic west antarctic rift system and a speculation on possible climate forcing the cenzoic west antarctic rift system characterized by cenozoic bimodal alkalic volcanic rocks extends over a largely ice covered area from the ross sea nearly to the bellingshausen sea it is bounded on one side by a spectacular 4 to 5 km high rift shoulder scarp maximum bedrock relief 5 to 7 km from northern victoria land queen maud mountains to the ellsworth whitmore horlick mountains jurassic tholeiites crop out with the late cenozoic volcanic rocks along the section of the transantarctic mountains from northern victoria land to the horlick mountains the cenozoic rift shoulder diverges here from the jurassic tholeiite trend and the tholeiites are exposed discontinuously along the lower elevation 1 2 km section of the transantarctic mountains to the weddell sea various lines of evidence no one of which is independently conclusive lead the authors as others have also suggested to interpret the following the transantarctic mountains part of the rift shoulder and probably the entire shoulder has been rising since about 60 ma at episodic rates of approximately 1 km m y most recently since mid pliocene time rather than continuously at the mean rate of 100m m y uplift rates vary along the scarp which is cut by transverse faults the authors speculate that this uplift may have climatically forcedmore the advance of the antarctic ice sheet since the most recent warm period they suggest a possible synergistic relation between episodic tectonism mountain uplift and volcanism in the cenozoic west antarctic rift system and waxing and waning of the antarctic ice sheet beginning about earliest oligocene time less

body wave crustal attenuation characteristics in the garhwal himalaya india we estimate frequency dependent attenuation of p and s waves in garhwal himalaya using the extended coda normalization method for the central frequencies 1 5 2 3 4 6 8 10 12 and 16 hz with earthquake hypocentral distance ranging from 27 to 200 km forty well located local earthquake waveforms were used to study the seismic attenuation characteristics of the garhwal himalaya india as recorded by eight stations operated by wadia institute of himalayan geology dehradun india from 2007 to 2012 we find frequency dependent p and s wave quality factors as defined by the relations q p 56 8f 0 91 0 002 and q s 151 8f 0 84 0 002 by fitting a power law frequency dependence model for the estimated values over the whole region both the q p and q s values indicate strong attenuation in the crust of garhwal himalaya the ratio of q s q p 1 obtained for the entire analyzed frequency range suggests that the scattering loss is due to a random and high degree of heterogeneities in the earth medium playing an important role in seismic wave attenuation in the himalayan crust

relating the spatial variability of chemical weathering and erosion to geological and topographical zones abstract the relationship between the spatial variability of soil elements weathering and erosion rates can be very complex topography abruptly changing elevation gradients and slopes of varying geological composition exert an important influence on weathering trajectories and erosion this complex interconnectivity is only rarely addressed in weathering studies the main objectives of this investigation are therefore to relate weathering and erosion to various and geomorphic units in a dry alpine and threshold landscape having steep slopes kan catchment tehran province iran a number of common weathering indices were tested using a genetic algorithm the best indices are the k na ti ratio the wip weathering index according to parker and the pi product index according to ruxton however the recently suggested 4si m r2 and m f wmin systems discriminate weathering trends more accurately our results show that these soils have a low to moderate weathering stage weathering trajectories point to the active formation of kaolinite and oxyhydroxides river sediments are slightly more weathered and contain the most weathered topsoils and suggest erosion in the catchment is predominantly due to topsoil removal chemical weathering is influenced by the dominant geomorphic units unconsolidated deposits of the quaternary and solid bedrock and landform features combination of altitude and slope aspect does not appear to have a significant impact on weathering denudation erosion rates were determined using meteoric 10be since the fluvial sediments did not contain enough quartz for in situ 10be analyses this procedure has higher uncertainties due to difficulties in estimating the depositional flux of meteoric 10be due to tectonic uplift the erosion rates are very high to maintain a soil layer soil production rates must be also high although annual precipitation is relatively low slope and soil dynamics seem particularly high which leads to a fast turnover of the soil material and maintains the weathering intensity at a rather low to intermediate level

assessment of weathering processes effect on engineering properties of alvand granitic rocks west of iran based on weathering indices the alvand batholith is one of the largest plutonic bodies in the west of iran in this research several physico mechanical tests have been performed on granodiorite and porphiroid monzogranite consisting of five degrees of weathering in hamedan area west of iran furthermore weathering process of alvand granitoid is studied by chemical analysis and petrographical studies the results indicated that engineering properties of weathered granodiorite and monzogranite vary over the wide range depending on the degree of weathering on the other hand this research is focused on the assessment of relationship between weathering indices and uniaxial compressive strength for this reason some of the most important weathering indices are reviewed it should be noted that application of these chemical engineering and petrographical indices are good quantitative indicators for describing the degree of weathering using these indices for the assessment of uniaxial compressive strength of granodiorite and monzogranite rocks yields suitable and meaningful results

lapse time and frequency dependent attenuation characteristics of kumaun himalaya abstract we have analyzed local earthquake data set consists of 84 well located events recorded by a digital seismic network in the kumaun himalaya region during 2004 2007 to study seismic attenuation characteristics of the region single back scattering assumption is used to estimate coda q q c values of the region at frequency range of 1 5 3 6 8 12 and 18 hz for different lapse time window length the values of q c show a ubiquitous observation of frequency dependence and follow a substantially similar trend as observed in other tectonically active parts of the himalaya the lapse time dependencies of coda waves are investigated which reveal that by increasing lapse time window from 20 to 50 s q 0 q c at 1 hz increases from 64 2 to 230 19 while frequency dependent parameter n decreases from 1 08 to 0 81 increase in q c with lapse time indicates decrease in heterogeneity with depth the observed values of q 0 and n infer that the medium beneath the study area is highly heterogeneous and tectonically very active the variation of q c with lapse time at 1 5 hz follow a similar pattern with the theoretically predicted values of gusev 1995 although the frequency parameter n does not match with the model it may suggest that the turbidity decays rapidly with depth for the kumaun himalaya our results are comparable with those obtained from tectonically active regions in the world

q determined from local earthquakes in the south carolina coastal plain abstract coda q or qc is determined from the rate of coda decay in the coastal plain near charleston south carolina the mean of qc calculated from individual estmates is near 190 at 1 hz and increases to over 1650 at 10 hz a possible temporal change in qc is identified high values being associated with increased seismic activity during late 1977 temporal changes have been observed elsewhere and laboratory measurements of q under different stress states correlate high q with high stress a spatial variation in qc is identified increasing from west qc at 10 hz equal to 850 to east qc at 10 hz greater than 2100 across the coastal plain the demarcation of high to highest zones of qc is coincident with the western boundary of the innermost isoseismal of the charleston 1886 earthquake it is hypothesized that the 1886 earthquake was mislocated originally because of this spatial variation in energy attenuation that was unrecognized at that time

revisiting the thermally metamorphosed coals of the transantarctic mountains antarctica abstract petrographic and geochemical data for late permian coals and carbonaceous shales from the transantarctic mountains antarctica source polar rock repository prr were used to evaluate maturation levels and assess the effects of contact metamorphism coals were evaluated for locations in the southern transantarctic mountains the central transantarctic mountains and south victoria land including samples from the buckley mt glossopteris and queen maud formations and the weller coal measures these formations have been intruded by sills and dikes of the jurassic ferrar group 177 183 ma associated with the breakup of gondwanaland proximate 129 samples total sulfur 69 analyses vitrinite reflectance analysis 92 and petrographic composition 34 were determined one third of the samples have 50 ash yields dry basis a subset of samples 87 with 7 thus vm does not reveal true rank of the antarctic coals vitrinite reflectance rr typically surpasses that of inertinite the vm rr relationship for these coals does not follow that of coals matured by normal burial maturation but more closely follows that of intruded coals coke textures including isotropic coke and anisotropic mosaics vacuoles pyrolytic carbon and coked bitumen are observed indicating alteration by contact metamorphism and providing insights to the rank of the coal at the time of intrusion coarse grained circular and fine grained lenticular mosaic textures suggest coal rank at the time of intrusion was medium volatile bituminous coal maximum vitrinite reflectance 1 2 this would imply a burial depth by time of intrusion of 5 5 5 km assuming 25 c km or 4 km assuming 34 c km modern day background reflectance levels of 2 5 rr indicate continued post intrusion maturation possibly due to exposure to higher regional heat flow coals and carbonaceous shales from the polar rock repository prr can provide reliable petrographic and maturation data using reflectance to help decipher the burial history for various parts of the transantarctic mountains however geochemical data must be used with caution due to the high original inorganic content and possible formation of gypsum and changes in vm during long term storage hcl treatment removes some of the neoformed minerals but samples should be treated extensively with hcl hf to remove all silicate minerals prior to proximate and ultimate analysis to ensure more reliable data

investigation of physical deterioration of malayer granitic rocks using a new weathering coefficient kr4 the main aim of this research is to find the most appropriate weathering indices among geomechanical chemical and petrographical indices to characterize malayer granitic rocks in the study area physical weathering and hydrothermal alteration are predominant degradation phenomena therefore it is necessary to distinguish between the effect of these two phenomena and chemical weathering on mineralogy as well as on geomechanical rock properties the most important evidences of hydrothermal alteration are the selective sericitization of plagioclase and the occurrence of prehnite also statistical analyses including simple and multiple linear regressions were applied to identify those indices that are most influenced on the progression of weathering based on the simple regression analysis petrographical and chemical indices do not show any good trend by increasing weathering degrees r2 0 72 finally a new quantitative weathering index kr4 has been developed regarding quick absorption index p wave velocity vp point load index is and total porosity n all the mentioned parameters can be quickly and inexpensively determined by portable laboratory instruments this new index kr4 has strongly correlated with weathering degrees r2 0 96 based on some results it seems that kr4 could be more suitable and credible to numerically evaluate the physical weathering accompanied by hydrothermal alteration processes of the studied rocks

on the geochemical evolution of sedimentary rocks the average major element compositions of clastic sedimentary rock assemblages i e carbonates evaporites and iron formations not considered for various times in earth history archean early proterozoic late proterozoic phanerozoic are reported based largely on the compilations of f l schwab uncertainties in the averages are considerable there is little evidence of secular change in the average composition of sedimentary rocks during post archean times such data do not support the idea of a gradual change in composition of the upper continental crust from mafic to felsic composition trace element patterns in sedimentary rocks particularly ree and th distributions support the idea of constancy of upper crustal composition during the post archean the average composition of archean clastic sedimentary rocks differs significantly from the post archean average being enriched in na mg and ca and depleted in si and k such differences are consistent with the archean upper crust having a more mafic composition than post archean upper crust the trace element data further support this idea it is noted that the average composition of post archean clastic sedimentary rocks predicts to within a factor of 1 2 the composition of the exposed continental crust for the elements si al fe k mg and ti the abundances of ca and na are depleted in the sedimentary rocks due to the fact that the compositions of carbonates evaporites and seawater were not considered the average composition of archean clastic sedimentary rocks does not compare favourably with an independent estimate of archean upper crust composition being enriched in si k and depleted in ca fe mg and ti such a comparison indicates that the archean upper crust may have had a more felsic major element composition than previously thought

effects of rapid thermal alteration on coal geochemical and petrographic signatures in the springfield no 5 coal illinois basin abstract igneous intrusion into a coal bed can change the geochemical and petrographic properties of the coal including vitrinite reflectance maceral petrographic composition optical texture mineralogy stable isotope composition trace element composition and bulk geochemistry the intent of this study was to evaluate petrographic and geochemical changes in an intruded coal and compare them to trends seen in coals altered by normal burial maturation thereby evaluating whether or not the intruded coals followed a different maturation pathway the current study reports petrographic bulk geochemical proximate ultimate leco total organic carbon toc and rock eval pyrolysis data for a suite of samples from the springfield no 5 coal pennsylvanian desmoinesian in the southern part of the illinois basin where the coal had been intruded by a permian age peridotite dike petrographic analysis shows an increase in vitrinite reflectance rm from background levels of 0 55 0 63 up to 4 80 a loss in ability to differentiate liptinite macerals formation of isotropic coke and at the dike coal contact development of fine grained mosaic anisotropic coke texture volatile matter vm content decreases and fixed carbon fc content ash and mineral matter parr formula increase approaching the intrusion contact carbon increases whereas nitrogen hydrogen and oxygen decrease approaching the intrusion the presence of carbonate minerals confirmed by x ray diffraction and petrographic analysis has a significant impact on proximate and ultimate data however even after removal of carbonates trends for vm vs rm c vs rm and h vs c do not follow typical trends associated with normal burial coalification approaching the contact leco toc rock eval free oil content s1 remaining hydrocarbon potential s2 co2 from pyrolysis of the organic matter s3 and hydrogen hi and oxygen oi indices decrease whereas thermal maturity tmax c increases s2 vs rm and tmax vs rm diverge from the pathways seen in previous studies of coals that have undergone normal burial maturation geochemical data from this study suggest that the intruded springfield no 5 coal may have followed a maturation track that differed from that seen under normal burial maturation perhaps due to the geologically rapid high heating event associated with the emplacement of the intrusion it is also suggested here that the natural coke textures produced by this rapid geological heating may differ from those observed for metallurgical cokes produced under standard industrial coking conditions typically in an industrial coke oven a coal of this initial rank ro 0 6 would produce an isotropic coke rather than the fine grained circular anisotropic coke seen here however as variations in heating rate duration of heating maximum temperatures attained hydrothermal conditions and pressure are mostly unknown for the intrusive event it is not unreasonable to suggest that differences in these variables contributed to the higher anisotropy of the coke alternatively the development of this texture may reflect pre heating of the coal during the intrusion event

spatiotemporal variations in the b value of earthquake magnitude frequency distributions classification and causes abstract interpretation of the b value of earthquake frequency magnitude distributions has received considerable attention in recent decades this paper provides a comprehensive review of previous investigations of spatial and temporal variations in b value including their classification and possible causes based on least squares regression of seismicity data compiled from the neic iris and isc catalogs we find an average value of 1 02 0 03 for the whole earth and its two hemispheres consistent with the general view that in seismically active regions the long term average value is close to unity nevertheless wide ranging b variations 0 3 b 2 5 have been reported in the literature this variability has been interpreted to arise from one or more of the following factors prevailing stress state crustal heterogeneity focal depth pore pressure geothermal gradient tectonic setting petrological environmental geophysical characteristics clustering of events incomplete catalog data and or method of calculation excluding the latter all of these factors appear to be linked directly or indirectly with the effective state of stress although time dependent changes in b value are well documented conflicting observations reveal either a precursory increase or decrease in b value before major earthquakes our compilation of published analyses suggests that statistically significant b variations occur globally on various timescales including annual monthly and perhaps diurnal taken together our review suggests that b variations are most plausibly linked with changes in effective stress

aberrations in the coalification patterns of the offshore coalfields of northumberland and durham united kingdom abstract the offshore extensions of the northumberland and durham westphalian coalfields are formed of continuous and linked sequences of sediments which lie in contrasting structural regimes respectively basin and block the coalfields have suffered different geothermal histories offshore northumberland basin sediments endured low heating rates and low maximum temperatures to give seams which even at the base of the succession hardly reached vitrinite reflectances of roil 0 60 apart from raised values due to igneous activity the offshore durham block succession was exposed to higher temperatures and heating rates due to the proximity of the lower devonian weardale granite underlying the block which was re activated during carboniferous times these geothermal conditions not only led to higher levels of reflectance and steeper maturation gradients offshore in the block succession than offshore in coals of the basin but also produced contrasting relationships between correlations of vitrinite oil reflectance and volatile matter yield of coals for the two structural zones and probably also for other property relationships as well reflectance profiles have been modified due to three circumstances first considerable variation locally in the raising of reflectance levels caused by igneous activity second lowering of vitrinite reflectance values due to arenaceous sediments being deposited immediately on top of vitrinite precursors within the coal forming organic matter and third possible interference from liptinite rich accumulations within coal seams or near to them in the succession which exuded aliphatic materials relatively early in coalification which were then absorbed by vitrinites or more likely deposition of the vitrinite precursors in a marine near marine and calcium rich environment so reducing reflectance values on coalification similar contrasting property relationships to those described here may have been produced by lower devonian granitoid bodies which have been identified on the north sea high if they also were re activated during the carboniferous

the ciw index a new chemical index of weathering abstract a new chemical index of weathering that can be applied to modern soils and precambrian paleosis is proposed ciw al2o3 the value of this index increases as the degree of weathering increases and the difference between ciw index values of the silicate parent rock and soil or sediment reflects the amount of weathering experienced by the weathered material

coda q estimates in the andaman islands using local earthquakes the attenuation property of andaman island has been investigated analyzing coda waves from 57 local earthquakes in the magnitude range of 2 0 4 9 using the single backscattering model these earthquakes waveforms recorded on five broadband seismographs sited over the island from north to south during nov 2003 to march 2004 have been used to calculate the frequency dependent coda q q c applying the time domain coda decay method the coda q computed at central frequencies from 0 5 12 hz and five lapse time windows from 40 to 80 s progressively increases from 105 f 0 88 in the north andaman to 135 f 0 79 in the south andaman with an average of 119 f 0 80 the average q c values vary from 75 42 at 0 5 hz to 697 54 at 12 hz central frequency for 40 s lapse time window while for 80 s lapse time window its variation is from 117 38 at 0 5 hz to 1256 115 at 12 hz the q c estimated at different lapse times manifests a significant variation from 122f 0 75 to 174f 0 73 corresponding to lapse time window lengths of 40 and 80 s respectively the variation of q c with frequency lapse time and also with the location of seismograph reflects the marked structural and compositional inhomogeneity with depth along the andaman islands these observations are well correlated with the seismicity pattern and distinct high angle subduction beneath the island

the mesozoic victoria basin vanished link between antarctica and australia the transantarctic mountains tam are the largest non compressional mountain belt in the world their origin is traditionally related to crustal thickening during the jurassic ferrar magmatic event that was followed by episodic uplift in the early and late cretaceous and since the paleocene this concept of a long lived morphological high constitutes a base of virtually all gondwana reconstructions and global climate models here we demonstrate that crossover age relationships between thermochronological apatite fission track data and stratigraphic information contradict this established interpretation instead these data together with a wealth of independent thermal indicators and geological evidence require the existence of a vast intra gondwana basin between at least late triassic and late cretaceous times including during the ferrar magmatic event referred to here as the mesozoic victoria basin mvb this basin formed during crustal extension across the paleo pacific margin of antarctica and australia uplift of the tam with associated basin inversion commenced only with the development of the west antarctic rift system in paleogene times the recognition of the long lived mvb has primary consequences for the general understanding of the landscape of gondwana and the breakup between antarctica and australia west antarctic rifting and uplift of the tam and global long term climate evolution and faunal radiation

attenuation characteristics of coda waves in mainland gujarat india abstract the attenuation characteristics based on coda waves of mainland gujarat india have been investigated in the present study the broadband waveforms of 53 local earthquakes mw 1 1 3 3 having focal depths in the 6 0 33 6 km range recorded at five stations of mainland gujarat region has been used for the analysis the frequency dependent relationships q q0fn for coda q qc and dependency of coda q on lapse time windows have been determined for the said region the average lapse time dependent coda q relations estimated for the region are qc 87 13 f 1 01 0 06 lapse time 30 s qc 112 20 f 0 94 0 08 lapse time 40 s and qc 120 22 f 0 76 0 07 lapse time 50 s the increase in qc values with lapse time shows the depth dependence of qc as longer lapse time windows will sample larger area the observed quality factor is strongly dependent on frequency and lapse time which indicates that the upper lithosphere is more heterogeneous and seismotectonically active while the lower lithosphere is homogeneous and relatively less active a comparison of the coda q estimated for mainland gujarat region with those of nearby kachchh and saurashtra regions shows that mainland gujarat region is more heterogeneous the rate of decay of attenuation q 1 with frequency for the relations obtained here is found to be comparable with those of other regions of the world though the absolute values differ the obtained relations are expected to be useful for the estimation of source parameters of the earthquakes in the mainland gujarat region where no such relations were available earlier these relations are also important for the simulation of earthquake strong ground motions in the region

the influence of heating rates on organic matter in laboratory and natural environments abstract this contribution to the festschrift relates to one of marie theresa mackowsky s industrial interests heating rate but it is not solely focussed within the field of industrial coking one intention is to stress the importance of heating rate in the natural environment to illustrate its broad pervasiveness first discussed however are the effects of heating rate on the appearance optical properties and molecular structures of organic matter in laboratory experiments before considering instances of the influence of heating rate variation on sedimentary organic matter within the natural environment notable illustrations within igneous provinces in the midland valley of scotland and north east england are described heating rate is obviously only one of a number of factors involved in the ultimate development of coal rank or level of organic metamorphism but the instances cited here emphasize that heating rate is not only an important factor in industrial carbonisation but is also a widely effective contributor to the variable maturation of crustal organic matter

effect of anigneous intrusion on oil shale at rundle australia abstract elemental analyses x ray diffraction thermal and isotopic analyses gas chromatography mass spectrometry electron spin resonance nuclear magnetic resonance spectroscopy and demineralizing techniques have been used to evaluate the effect of a small igneous intrusion on rundle oil shale each set of results contributes to an overall appreciation of how in situ pyrolysis of a highly aliphatic kerogen occurs as in previous studies application of a range of methods gives a better understanding than any of the techniques on its own significant conclusions are as follows 1 the shale samples closest to the intrusion contain the least organic matter 2 a micro reservoir for expelled volatiles was identified 1 m below the intrusion 3 the hydrogen deficient carbonaceous residue remaining close to the intrusion produces no oil on further heating and 4 the major effect of the intrusive event was the in situ pyrolysis of the oil shale the severity of alteration decreasing with distance from the contact

methane release from igneous intrusion of coal during late permian extinction events abstract unusually large and locally variable carbon isotope excursions coincident with mass extinctions at the end of the permian period 253 ma and guadalupian epoch 260 ma can be attributed to methane outbursts to the atmosphere methane has isotopic values 13c low enough to reduce to feasible amounts the carbon required for isotopic mass balance the duration of the carbon isotopic excursions and inferred methane releases are here constrained to 10 000 yr by counting annual varves in lake deposits and by estimating peat accumulation rates on paleogeographic maps the most marked carbon isotope excursions form linear arrays back to plausible methane sources end permian siberian traps and longwood bluff intrusions of new zealand and end guadalupian emeishan traps of china intrusion of coal seams by feeder dikes to flood basalts could create successive thermogenic methane outbursts of the observed timing and magnitude but these are unreasonably short times for replenishment of marine or permaf

hydrothermal venting of greenhouse gases triggering early jurassic global warming abstract the climate change in the toarcian early jurassic was characterized by a major perturbation of the global carbon cycle the event lasted for approximately 200 000 years and was manifested by a global warming of 6 c anoxic conditions in the oceans and extinction of marine species the triggering mechanisms for the perturbation and environmental change are however strongly debated here we present evidence for a rapid formation and transport of greenhouse gases from the deep sedimentary reservoirs in the karoo basin south africa magmatic sills were emplaced during the initial stages of formation of the early jurassic karoo large igneous province and had a profound influence on the fate of light elements in the organic rich sedimentary host rocks total organic carbon contents and vitrinite reflectivity data from contact aureoles around the sills show that organic carbon was lost from the country rocks during heating we present data from a new type of geological structures termed breccia pipes rooted in the aureoles within the shale of the western karoo basin the breccia pipes are cylindrical structures up to 150 meters in diameter and are mainly comprised of brecciated and baked black shale thousands of breccia pipes were formed due to gas pressure build up during metamorphism of the shales resulting in venting of greenhouse gases to the toarcian atmosphere mass balance calculations constrained by new aureole data show that up to 1800 gt of co2 was formed from organic material in the western karoo basin about 15 times this amount of co2 27 400 gt may have formed in the entire basin during the intrusive event u pb dating of zircons from a sill related to many of the pipes demonstrates that the magma was emplaced 182 5 0 4 million years ago this supports a causal relationship between the intrusive volcanism the gas venting and the toarcian global warming

226ra 238u and 228th 228ra disequilibrium as weathering indices in beach sand sediments associated with granitoids from cyclades greece abstract radioactive secular disequilibrium measured as the absolute difference from 1 of the 226ra 238u and 228ra 228th ratios have been used to determine weathering extent twenty eight samples from beach sands of cyclades islands all of them being the weathering products of the local granitic plutons are studied for their secular disequilibrium in both 238u and 232th series 226ra 238u and 228th 228ra respectively the results are compared to weathering indices already in use worldwide and suggest a significant linear correlation of u series disequilibrium with wip alkaline and alkaline earth element leaching and pwi silica leaching for the beach sands studied and significant non linear correlations with cia chemical index of alteration and pia plagioclase index of alteration considering only the heavy mineral enriched samples significant correlations exist between u series disequilibrium and cia ciw chemical index of weathering and pia therefore with an appropriate choice of the weathering index and samples both u series and weathering index can recover the extent of chemical weathering on the other hand the use of th series disequilibrium as a weathering index is limited due to 228th and 228ra geochemistry and especially due to their short radionuclide half lives u series disequilibrium can therefore be used as a relatively sensitive weathering index in sediments consistent with cia ciw and pia indices however the mineralogical composition must be considered more specifically the mineral content of the sediments should involve considerable amounts of sensitive to weathering minerals e g fe mg minerals as well as feldspars

the detection of weathering in coal by petrographic rheologic and chemical methods abstract this study examines petrographic rheologic proximate and ultimate analyses techniques to investigate the effects of natural weathering on coal the applicability of such tests to both the detection of weathering and to the prediction of the properties of a fresh coal based upon analyses of a weathered sample is discussed rheologic parameters and a petrographic staining technique showed the most sensitive response to weathering the latter test is considered the most suitable of these for the detection of weathering as it is independent of prior knowledge of the properties of the fresh coal and of the petrographic composition a petrographic approach is also considered most suitable for estimation of fresh coal characteristics from weathered samples rank may be closely approximated and petrographic type determined microscopically even on highly weathered samples and these two parameters may be used to estimate properties such as volatile matter calorific value and dilatation minor modification should be made to vitrinite reflectance measurements according to the degree of weathering as revealed by selective staining

a short interval of jurassic continental flood basalt volcanism in antarctica as demonstrated by 40ar39ar geochronology a continental flood basalt province the ferrar group kirkpatrick basalt and ferrar dolerite crops out along 3000 km of the transantarctic mountains in antarctica and is temporally related to the break up of gondwanaland although a wide range of dates between 90 and 193 ma have been published for the kirkpatrick basalt it is now recognized that the young dates reflect non ideal behavior of ar in the matrix in order to refine the geochronology feldspar separates have been analyzed by the 40ar39ar incremental heating method the main objectives are to constrain the duration of extrusive activity and the timing of volcanism along the outcrop belt basalt samples have been studied from the three principal outcrop areas yielding the following apparent ages central transantarctic mountains 176 8 0 5 ma south victoria land 176 4 0 4 ma north victoria land 176 6 0 7 ma ages from different stratigraphic levels within each area and from the three different areas are not analytically distinct the data imply that the eruptive activity which produced the kirkpatrick basalt occurred within a short interval of less than about 1 m y at 176 6 1 8 ma over an area which included more than 1200 km of the transantarctic mountains the jurassic volcanism in antarctica represents a short episode of magmatism comparable in duration with other well dated continental flood basalt provinces the linearly extensive outcrop of the ferrar province and the rapid eruption of the lavas suggests that lithospheric stretching exerted a major control on magmatism the poorly constrained age of the bajocian bathonian boundary makes the previously suggested connection between ferrar volcanism and an extinction event at that boundary uncertain

attenuation of coda waves in the garhwal himalaya india abstract q c estimates have been obtained by analysing coda waves of seven local earthquakes recorded in the garhwal himalaya the earthquakes have their epicentral distances within 100 km focal depths up to 20 km with 2 4 m l 4 9 q c values have been computed at central frequencies of 1 5 3 0 6 0 12 0 and 18 0 hz for different earthquake stations falling in the lapse time window of 30 60 s using a single backscattering model the mean value of q c shows a dependence on frequency varying from 206 at 1 5 hz to 2090 at 18 hz the frequency dependence average q c relationship q c q 0 f n has been obtained for the region as q c 126 f 0 95 which indicates that attenuation at higher frequencies is less pronounced q c values estimated for the region represent the average attenuation properties for a surface area of about 20 000 km 2 in a circular shape with a radius of about 80 km assuming single backscattering

the impact of rapid heating by intrusion on the geochemistry and petrography of coals and organic rich shales in the illinois basin abstract igneous intrusion into organic rich sedimentary rocks and coals has been suggested as a factor in the large scale release of 13c depleted thermogenic ch4 which may have led to global warming and mass extinction events in the geologic past if a significant release of 13c depleted thermogenic ch4 results from the intrusion of coal or organic rich rocks then it should produce 13c enriched residual coal and dispersed organics in rocks adjacent to the intrusion due to the release of isotopically lighter ch4 gas a review of the literature suggests only minor changes in the 13corg of coals adjacent to intrusions however a few studies have shown that changes in 13corg in intruded shales may be slightly more pronounced the current study further evaluates the geochemical isotopic and petrographic changes that result from contact metamorphism and specifically compares the intrusion of coal to that of an organic rich shale collected from the same general vicinity data for two different transects of intruded pennsylvanian coal danville no 7 coal and an intruded organic rich shale in the southern part of the illinois basin are presented both transects show similar increases in mean vitrinite reflectance rr reflectance increases from background levels of 0 66 to 4 40 in the danville no 7 coal and 0 71 to 4 78 in the organic rich shale in addition both transects show the formation of isotropic coke and even development of fine circular mosaic anisotropic coke structure at and near the contact with the intrusion along with the visual loss of liptinites at higher reflectances in the danville coal transect volatile matter n h s and o decrease whereas fixed carbon c and ash increase approaching the intrusion the coal shows a marked decrease in remaining hydrocarbon potential s2 and hydrogen index hi and an increase in tmax c trends in most of the rock eval parameters for the organic rich shale are less clear due to variations in the amount of organic matter present but a significant increase in thermal maturity tmax 0c is observed no systematic changes in 13c occur in the no 7 coal transect as the intrusion is approached with 13c varying between 25 4 and 24 8 the organic rich shale transect shows a minor 1 2 enrichment in 13c from 25 2 to 24 0 within 2 m of the intrusion these isotopic shifts are not of a magnitude that would be expected if associated with a large scale release of thermogenic ch4 in addition no evidence exists in either transect for 13c depleted condensed gas or pyrolytic carbon at the intrusion contact that could have moderated the isotopic signature these data agree with those reported previously that indicate no clear isotopic evidence for large scale ch4 generation due to rapid heating by igneous intrusion into coals or sedimentary rocks

properties of a lacustrine subbituminous k1 seam with special reference to the contact metamorphism soma turkey abstract the subbituminous k1 seam in the middle miocene soma formation of western turkey reaches a thickness of 24 m typical samples on an air dried basis have 9 5 14 2 moisture 4 3 13 8 ash and 0 57 2 54 total sulphur the coal rank parameters and non agglomerating behaviour show that the coals are of subbituminous a rank the k1 seam is huminite rich coal with a mean random ulminite reflectance rr between 0 46 and 0 49 fluorescence emission measurements show that the sporinite cutinite resinite and alginite present have typical fluorescence spectra between 460 and 700 nm the soma formation was intruded by an olivine basalt during the pliocene pleistocene which caused local contact metamorphism at the top of the k1 seam on the basis of proximate ultimate and petrographic analyses the intruded seam can be divided into normal coal transition zone and natural coke intervals each differing in their degree of metamorphism moisture volatile matter hydrogen and oxygen contents very rapidly decrease close to the contact point with the intrusion whilst calorific value carbon content and mean random reflectance value increase a diagram ofo c versus h c also shows a distinct increase in rank caused by the intrusion minor illite siderite and plagioclase feldspar are present in the natural coke samples butpyrrhotite is not observed mineralogical geochemical and reflectance studies indicate that the general temperature during formation of natural coke was probably relatively low

coal weathering and laboratory artificial coal oxidation abstract coal weathering and laboratory artificial oxidation have been topics of much discussion and extensive research since over a century ago as they cause a profound effect on the chemistry of coal and its technological properties and as they induce distinct and irreversible changes to coal macromolecular structure this article focuses on the effect of coal weathering and laboratory artificial oxidation on the microscopic appearance of coal its microstructure as well as coal optical properties the coal petrographic effects of in situ weathering and laboratory oxidation have been a topic of research within the international committee for coal and organic petrology iccp for years and involve discoloration of macerals formation of oxidation rims and changes in polishing relief with formation of micropores microcracks and microfissures regarding oxidation rims their presence as a result of in situ weathering and laboratory oxidation is petrographically well documented vitrinite reflectance measured on weathered or artificially oxidised coals of different ranks exhibits a differential trend depending on conditions such as temperature and duration of exposure also the decline of fluorescence intensity has been reported for these coals in addition to the overview of coal petrographic oxidation features of weathered and laboratory oxidised coals at ambient to low temperature conditions the influence of these processes on coal chemical physical and technological properties has been discussed previous investigations have shown that coal weathering and laboratory artificial oxidation affect the suitability of coal for technological uses and provide self heating or spontaneous combustion risk to fossil resources in coal deposits in open air storage facilities and discard dumps silos and bunkers oxidation also affects coal transport facilities preparation and processing techniques as well as the prediction of coal combustion and carbonisation behaviour changing cokemaking requirements it has been similarly shown in numerous research programs and investigations that it poses a detrimental effect on coal liquefaction gasification and manufacturing of coal based carbon materials in addition low temperature oxidation is considered a primary source of heat leading to self heating and uncontrolled spontaneous combustion further the review provides a broad overview of practical importance of coal weathering and coal oxidation research to coal conversion technologies and final coal utilization products supported by numerous laboratory investigations the article presents also a short summary of optical microscopy and non optical microscopy methods applied to identify coal weathering and laboratory artificial oxidation it is hoped that issues raised in the review article will enhance further debates and novel ideas in coal and coal related research

the coalification of south african coal abstract it has been generally accepted that the variation in rank of south african coal is essentially due to the metamorphic effect of dolerite dykes and sills however no satisfactory explanation could be given for the fact that true anthracite has not been formed adjacent to dykes and transgressive sills in those south african coal fields where the rank of the coal is normally low in these areas the coal close to the intrusives is often referred to as burnt a detailed examination of the contact metamorphism of south african coal by dolerite intrusives shows that a dyke or sill affects the coal to variable distances generally from 0 6 to 2 times the thickness of the intrusive and that this distance is independent of the rank of the coal outside the contact aureole this is explained by an initial episode of contact metamorphism while the coal was still in the lignite stage of coalification followed by burial metamorphism during which the paleogeothermal gradient increased in an easterly direction this regional increase in paleogeothermal gradient is probably related to the large scale magmatic activity that culminated in the extrusion of the drakensberg basalts and the break up of gondwanaland

archean chemical weathering at three localities on the canadian shield abstract sapropelite developed on a granodiorite basement below the archean steeprock group in the western superior structural province of canada weathered materials from a 3 15 ga granitic basement to the archean yellowknife supergroup in the slave structural province and weathered detritus from contemporaneous komatiites and gneissic basement of the archean prince albert group in northern churchill structural province have been analysed the deviation of the weakly metamorphosed weathered material from the chemical composition of their precursors is comparable to that seen in more recent weathered profiles from similar source materials this includes the enhancement of ferric to ferrous iron ratios and potash to soda lime and magnesia ratios there is also an increase in lighter ree and a depletion of heavier ree quartz rich sediments immediately above the unconformity derived from the basement granitoids may be enriched in aluminum and iron and yield chloritoid under proper metamorphic conditions sediments formed from mixed sources such as weathered gneissic basement and contemporaneous komatiitic volcanics yield anomalous resistate sedimentary mixtures such as chromiferous quartzites based on the data given here there is no need to postulate that different weathering and or ground water systems were operative during the archean compared to more recent times on the other hand the complicated weathering and diagenetic history that altered material undergoes below a subsiding unconformity relies as much or more on the buffering capacity of the enclosed rock mass as on the atmospheric conditions prevalent at the time of weathering hence weathering profiles old and new are more a response to local environmental conditions within the rock than the composition of the atmosphere

effects of igneous intrusions on coalbed methane potential gunnedah basin australia abstract the gunnedah basin nsw australia contains more than 500 gt of coal and has been the subject of recent coalbed methane exploration large areas of the basin contain igneous intrusions and large areas of coal have been heat affected as a consequence a detailed study has been undertaken of coal seams intersected in a cored coalbed methane exploration drillhole in which two sill form igneous intrusions are present comparisons are made between coals that are unaltered and coals that have been heat affected using petrographic and chemical data coal seam gas desorption data and gas chemical analysis data results demonstrate that the two igneous intrusions have had a very positive effect on coalbed methane development the gas content in a number of heat affected coal seams within thermal aureoles above and below the sills is substantially higher than in adjacent unaffected coal seams in addition the intrusions have had little effect on gas quality the coals in the heat affected zone were found to contain gas with approximately 95 methane the coals in the thermal aureoles were found under the microscope to contain characteristic micropores and slits which collectively may serve to enhance gas adsorption capacity permeability and gas desorption gas contents below each of the sills is substantially higher than above the sill confirming earlier results that the sills appear to have acted as a reservoir seal during and for some time after intrusion the background coal rank in acm yannergee ddh 1 is in the high volatile bituminous range the igneous intrusions have resulted in an increase in rank such that large areas of coal have moved into the optimal thermogenic gas generation window this rank increase has affected a major part of the coal bearing sequence

depth dependent seismic attenuation in the granada zone southern spain abstract coda q estimates for the granada basin southern spain are obtained by analyzing earthquakes occurring within or close to the borders of this area the data set is composed of 54 earthquakes with local magnitudes ranging between 2 2 and 4 0 and with epicentral distances to the nearest station smaller than 10 km a single scattering process is assumed coda q values obtained show a clear dependence on frequency according to the relationship q q o f n where n ranges from 0 81 to 0 89 after removing the main site effects and discussing the possible multiple scattering influence the lapse time dependence is interpreted as due to attenuation variations with depth this result agrees with the variation of coda q obtained by using different sets of events with increasing hypocentral depth ranges

permian triassic boundary in the central transantarctic mountains antarctica the permian triassic boundary occurs within a relatively complete terrestrial sequence in the shackleton glacier area of the central transantarctic mountains the boundary is within a 7 to 10 m thick interval between the permian glossopteris flora and the lower triassic lystrosaurus fauna this interval representing on the order of 200 k y records some of the events that occurred in the transition from the permian to triassic in the best documented section at graphite peak in the beardmore glacier region protohaploxypinus microcorpus zone palynomorphs which we assign to the latest permian record the declining glossopteris flora and occur near the top of the buckley coal measures just below a previously reported major negative 13c excursion in the shackleton glacier area the permian glossopteris flora including fossil wood roots and leaves occurs within the lower part of the fremouw formation the antarctic lystrosaurus assemblage of early triassic age has several species in common with the south african fauna that lived 20 to 35 closer to the equator the migration of vertebrates from southern africa into antarctica in the early triassic supports hypotheses of runaway greenhouse warming possibly related to co2 emissions from siberian flood basalts and large methane gas releases changes in flora bracketing the first of the major negative 13c anomalies near the boundary in antarctica and in east greenland support the hypothesis that a global event perhaps through mutations caused by enhanced ultraviolet radiation may have played a role in the destruction of floras

geochemical and petrographic alteration of rapidly heated coals from the herrin no 6 coal seam illinois basin abstract coals altered by rapid heating events i e those intruded by dikes and sills are thought to follow a different geochemical maturation pathway than coals altered through diagenesis if an igneous intrusion alters the petrographic and geochemical properties of a coal the effect should also be observable in the coal s molecular structure in this study we evaluate whether coals altered by rapid heating follow distinct maturation trends from coals that were altered by slower heating burial maturation petrographic geochemical and micro ftir analyses were performed on a series of pennsylvanian illinois basin coal samples collected at various distances from a permian igneous dike standard coal characterization techniques including vitrinite reflectance and proximate and ultimate analyses provide valuable insights on the maturation pathways experienced by rapidly heated coals these techniques were coupled with reflectance micro ftir to provide a better understanding of the molecular changes that occur in the coal structure during relatively short lived intensive heating events with decreasing distance to the intrusion coals have higher mean random vitrinite reflectance values rr within the dike alteration zone coking textures similar to those observed in industrial cokes are observed within 2 m of the intrusion geochemical data for hcl treated coals indicate an overall loss of h o and n and an increase in c approaching the dike intruded coals have higher volatile matter vm yields at high rank than coals of similar rank that result from normal burial maturation when plotted on a van krevelen diagram or seyler chart intruded coals follow different coalification trends than coals matured through normal burial diagenesis reflectance micro ftir analysis of collotelinite shows increased aromaticity with rank both the ratio of the aromatic ch stretching band at 3100 3000 cm 1 versus the aliphatic chx stretching bands between 3000 and 2800 cm 1 ar1 and the ratio of the aromatic out of plane deformation bands between 900 700 cm 1 versus the aliphatic chx band ar2 increase with increasing rr within the 3000 2800 cm 1 region there is an increase in the area under the asymmetric ch3 peak at 2960 cm 1 relative to the asymmetric ch2 peak at 2920 cm 1 with increased rank within the 900 700 cm 1 region the overall intensity of the 750 cm 1 peak aromatic rings with four adjacent h atoms relative to the 870 cm 1 peak aromatic rings with one isolated h atom increases up to 2 5 rr likely reflecting a lower degree of substitution dos of alkyl groups on aromatic ring sites the prevalence of the 750 cm 1 peak at high rank may represent a lower degree of condensation of aromatic rings in the structure of intruded coals compared to normally matured coals

coda q estimates in the koyna region india the coda q q c have been estimated for the koyna region of india the coda waves of 76 seismograms from thirteen local earthquakes recorded digitally in the region during july august 1996 have been analyzed for this purpose at nine central frequencies viz 1 5 2 0 3 0 4 0 6 0 8 0 12 0 16 0 and 24 0 hz using a single backscattering model all events with magnitude less than 3 fall in the epicentral distances less than 60 km and have focal depths which range from 0 86 to 9 43 km for the 30 sec coda window length the estimated q c values vary from 81 to 261 at 1 5 hz and 2088 to 3234 at 24 hz whereas the mean values of q c with the standard error vary from 148 13 5 at 1 5 hz to 2703 38 8 at 24 hz both the estimated q c values and their mean values exhibit the clear dependence on frequency in the region and a frequency dependence average attenuation relationship q c 96f 1 09 has been obtained for the region covering an approximate area of 11 500 km2 with the surfacial extent of about 120 km and depth of 60 km

contrasting secondary mobility of ti p zr nb and y in two metabasaltic suites in the appalachians substantial mobility of high field strength hfs elements ti y p zr and nb during greenschist facies metamorphism of two metabasaltic suites from the appalachians the ascot formation of southeastern quebec and the arbuckle brook formation of nova scotia is attributed to the presence of co2 in the fluid phase during metamorphism the style of the mobility exhibited by these two suites is different in the ascot formation metasomatism affected rocks rich and poor in carbonates it led to enrichment in some hfs elements and depletion in others in contrast in the arbuckle brook formation there was depletion in co2 rich rocks of all hfs elements and consequently much less fractionation between hfs elements these differences may be explained by the relative effectiveness of buffering in the two suites in the ascot formation buffering was ineffective and several different mineral assemblages were developed reflecting a range in mobility of hfs elements was controlled by chemical potential diffe

release of methane from a volcanic basin as a mechanism for initial eocene global warming a 200 000 yr interval of extreme global warming marked the start of the eocene epoch about 55 million years ago negative carbon and oxygen isotope excursions in marine and terrestrial sediments show that this event was linked to a massive and rapid approximately 10 000 yr input of isotopically depleted carbon it has been suggested previously that extensive melting of gas hydrates buried in marine sediments may represent the carbon source and has caused the global climate change large scale hydrate melting however requires a hitherto unknown triggering mechanism here we present evidence for the presence of thousands of hydrothermal vent complexes identified on seismic reflection profiles from the voring and more basins in the norwegian sea we propose that intrusion of voluminous mantle derived melts in carbon rich sedimentary strata in the northeast atlantic may have caused an explosive release of methane transported to the ocean or atmosphere through the vent complexes close to the palaeocene eocene boundary similar volcanic and metamorphic processes may explain climate events associated with other large igneous provinces such as the siberian traps approximately 250 million years ago and the karoo igneous province approximately 183 million years ago