assessment of the contribution of in situ combustion of coal to greenhouse gas emission based on a comparison of chinese mining information to previous remote sensing estimates greenhouse gas ghg emission from geological sources such as volcanic activity seabed gas hydrate release hydrocarbon seepage as well as uncontrolled combustion of fossil fuels is erratic and difficult to quantify in this paper we assess the ghg emission due to spontaneous combustion of in situ coal deposits coal fires this problem is aggravated by human intervention mining activities which on the other hand allows better constrained estimations and improved reduction strategies provided modern mining practices are employed in this study we present three case studies on coal fire related ghg emission quantification on provincial scale in china and we propose an integrated quantification aimed at the joint analyses of local knowledge geophysical data and remote sensing data with the objective to retrieve unbiased numbers as a first estimate we conclude that the emissions of ghgs from coal fires in china account for well less than 0 22 of all global fossil fuel related co2 emissions most likely even less than 0 1 this is much less than the previously estimated 2 3

impact of underground coal fire on coal petrographic properties of high volatile bituminous coals a case study from coal fire zone no 3 2 in the wuda coalfield inner mongolia autonomous region north china abstract the wuda coalfield located in the inner mongolia autonomous region north china is known as one of china s major source of prime coking coals and a site of well researched and well documented underground coal fires the underground coal fire at the coal fire zone no 3 2 is situated in the active coal mine of suhai tu located in the north westerly part of the wuda coalfield the present paper investigates the impact of the underground coal fire on the coal seam no 10 by application of coal petrographic methods including detailed characteristic of macerals and other coal components maceral analysis microstructural analysis and vitrinite reflectances performed on 1 coal grains lacking impurities microfractures dark oxidation rims 2 on dark rimmed vitrinite as well as 3 on low temperature semi coke the investigated coal seam no 10 represents a high volatile a bituminous coal and is dominated by vitrinite followed by inertinite with minor amounts of liptinite and by non isotropic low temperature semi coke the microstructure of the oxidatively and thermally altered coals is represented by 1 extensive non tectonic microfissures and non tectonic microfractures i e shrinkage microfractures leading to defragmentation of coal grains 2 dark oxidation rims observed at grain margins non tectonic microfissures and microfractures and by 3 devolatilisation micropores random vitrinite reflectances measured in 1 coal grains lacking impurities microfractures and dark oxidation rims and in 2 dark rimmed vitrinite at non tectonic microfissures and fractures reveal significant lateral variations the presence of low temperature semi coke and its marked lower reflectance values are indicative of thermal alteration induced by the underground coal fire in the coal fire zone no 3 2 the results obtained from the performed analyses of organic matter point to both low temperature oxidation and low temperature pyrolysis processes the applied coal petrological approach revealed characteristic changes to the coal s microstructure its petrographic composition as well as to optical properties induced by the underground coal fire

measurement of sub surface strata behaviour in bord and pillar mining a case study abstract ranigunj coalfield india has been facing significant problems due to subsidence as a result of underground mining of coal seams the occurrence of the thick seams in close proximity shallow depth great variation in the nature of superincumbent strata from site to site followed by the slow rate of extraction has aggravated subsidence problems in the recent past many such workings have collapsed damaging a large number of surface structures in view of the aforesaid need a comprehensive project financed by the ministry of energy coal was undertaken by the department of mining engineering indian institute of technology kharagpur at a colliery in ranigunj coalfield this investigation revealed that the caving horizon occurred at 4 times the extracted seam height which differs from the findings in the u k u s a and australia also it appears possible to estimate strata displacements from geological and physicomechanical information from the overlying rocks using the bending moment principle further it was observed that the shallow workings could give rise to a sink hole type of subsidence which is dangerous and could adversely affect the environment safety of the public and properties

positive and negative impacts of longwall mine subsidence on a sandstone aquifer subsidence due to longwall underground coal mining changes the hydraulic properties heads yields and in some cases the groundwater chemistry of overlying bedrock aquifers a 7 year study of a sandstone aquifer overlying an active longwall mine in illinois has supported a comprehensive model of these impacts subsidence caused increases in permeability and storativity over the longwall panel these changes initially caused a major decline in water levels in the sandstone but the aquifer recovered slightly within a few months and fully within several years after mining the enhanced hydraulic properties combined with potentiometric recovery resulted in a zone of greater well yield however at sites with very poor transmissivity and inadequate recharge pathways recovery may not occur also at the study site the physical enhancement was accompanied by a deterioration in groundwater quality from slightly brackish sodium bicarbonate water to more brackish water with increased sulfate levels

new mineral occurrences and mineralization processes wuda coal fire gas vents of inner mongolia five unique mineral assemblages that include the sulfates millosevichite alunogen anhydrite tschermigite coquimbite voltaite and godovikovite as well as the halide salammoniac and an unidentified phase according to x ray diffraction and eds data were found as encrustations on quartzofeldspathic sand and sandstone adjacent to coal fire gas vents associated with underground coal fires in the wuda coalfield of inner mongolia the mineral assemblage of alunogen coquimbite voltaite and the unidentified phase collected from the same gas vent is documented for the first time coquimbite also occurs as rosettes secondarily nucleated on a cryptocrystalline mass of alunogen coquimbite voltaite and the unidentified phase during storage in a sealed container at room temperature field observations analyses of vent gases sem images and mineral compositions suggest that the sulfates millosevichite alunogen coquimbite voltaite godovikovite and the unidentified phase crystallized in response to a complex sequence of processes that include condensation hydrothermal alteration crystallization from solution fluctuating vent temperatures boiling and dehydration reactions whereas the halide salammoniac crystallized during the sublimation of coal fire gas tschermigite and anhydrite formed by the reaction of coal fire gas with quartzofeldspathic rock or by hydrothermal alteration of this rock and crystallization from an acid rich aqueous solution variations in the mineral assemblages found at five gas vents are possibly due to differences in coal bed chemistry exchange reactions involving coal fire gas and the composition of sediment rock and aqueous solutions prior to the exhalation of gas at the surface as well as the temperature and cooling rate at a vent few studies have addressed the interaction of coal fire gas with sediment rock and aqueous solutions and the subsequent mineralization processes coal fires present opportunities for discovering rare and new mineral occurrences these minerals have potentially important environmental significance and may be vectors for the transmission of toxins coal fires also provide insight for the recognition in the geologic record of preserved mineral assemblages that are diagnostic of ancient fires

integration of ground subsidence hazard maps of abandoned coal mines in samcheok korea integrated techniques were developed applied and validated for the analysis of ground subsidence hazards by abandoned coal mines in samcheok korea using a geographic information system gis slope depth of drift distance from drift groundwater level permeability geology and land use were extracted or calculated from the digital elevation model topographic drift distribution borehole geologic and land use database by using the constructed spatial database the relations between the ground subsidence location and seven related factors were identified and quantified by frequency ratio fr weights of evidence woe logistic regression lr and artificial neural network ann models the relations were used as factor ratings in the overlay analysis to create ground subsidence hazard indices and maps the four ground subsidence hazard maps were reflected as the new input factors and integrated using fr woe lr and ann models to make a hazard map all of the subsidence hazard maps were validated by comparison with known ground subsidence locations that were not used in the analysis as a result the integrated ground subsidence hazard maps used four new subsidence related input factors that showed a greater accuracy 96 46 for fr 97 22 for woe 97 20 for lr and 96 70 for ann respectively than the individual ground subsidence maps 95 54 for fr 94 22 for woe 96 89 for lr and 94 45 for ann respectively using the first seven factors

aquifer protection during longwall mining of shallow coal seams a case study in the shendong coalfield of china large scale underground mining of shallow coal seams can have significant impacts on ground surface and potentially leads to incidental damage to the overlying aquifer with subsequent environmental hazards in order to deal with the apparent conflict between water protection and high production in underground mining an aquifer protection mining technique was trialed in panel 51201 in the shangwan colliery the shendong coalfield china overburden failure water level of the unconsolidated aquifer surface cracks and ground subsidence were monitored in a series of boreholes using borescope and also by observations in a nearby water well and by surface surveys monitoring results indicate that the aquifer protection mining technique can be successfully applied by modifying a few mining parameters such as mining height or advance rate under some suitable geological conditions the critical zone in the stratigraphy appears to be the weathered bedrock located immediately below the aquifer the weathered bedrock will remain impermeable after mining as long as its thickness is greater than the mining height the development of the mining induced overburden failure is affected by the key strata but ultimately controlled by the soft aquiclude such as the weathered zone it was observed respectively that the height of the caved zone was observed to be 5 to 6 times the mining height whilst the height of the fractured zone is about 10 to 11 times the mining height

field trials of aquifer protection in longwall mining of shallow coal seams in china the large scale mining of shallow coal seams has a significant impact on the overlying aquifers and surface ecological environment to protect the aquifers and maximize the coal resource recovery field trials were undertaken during the operation of the lw32201 in bulianta coal mine shendong china with a severely weathered rock swr layer and two key strata ks in the overlying strata aquifer protection in longwall mining aplm relies mainly on the rapid advance in some localized zones special measures should be taken to achieve the aplm including lowering mining height backfill and slurry injection to further understand the mechanism and applicable conditions of the aplm and validate the effectiveness of the aplm variation of the water table in the aquifer was observed as the longwall face passed through the zone this paper also discusses the mechanism and basic requirements of the aplm and the relationship between the fall of the water table and the surface subsidence the results of the field trials indicated that aplm in shallow coal seams could be successful under suitable conditions

epoch of large scale low temperature mineralizations in southwestern yangtze massif there exists a typical low temperature metallogenic domain in southwestern china which covers sichuan yunnan guizhou guangxi and hunan as a unique region in the world this domain is characterized by its large area about 900 000 km2 many kinds of mineralization au hg sb as p pb zn u ni mo pge barite calcspar and dispersed elements and complicated compositions and associations of ore deposits the southwestern yangtze massif is an important part of the low temperature metallogenic domain in southwestern china in recent years the authors have systematically studied the metallogenic epochs of p au sb low temperature mineralizations in southwestern yangtze massif by using rb sr sm nd and ar ar isotopic geochronolgical dating methods with the combination of previous data this paper has summarized the dating results and pointed out that there exist roughly 3 stages of large scale low temperature mineralization which are equivalent to late proterozoic early palaeozoic late sinian early cambrian late caledonian late silurian early devonian and yanshanian late jurassic middle cretaceous the phosphorite deposits barite deposits and ni mo pge deposits in the area were formed mainly in late proterozoic early palaeozoic with isotopic ages mainly ranging from 585 ma to 540 ma the au sb w deposits hosted in the precambrian low metamorphic clastic rocks were mainly formed in late caledonian with isotopic ages mainly ranging from 435 ma to 380 ma the sb deposits hosted in post cambrian strata were mainly formed in middle yanshanian with isotopic ages mainly ranging from 160 ma to 140 ma the carlin type gold mineralization and the hg mineralization in the area were mainly formed in middle and late yanshanain period with isotopic ages ranging from 170 ma to 80 ma

oxygen isotopic composition and chemical correlations in meteorites and the terrestrial planets recent models attempting to explain non mass dependent oxygen isotopic anomalies in meteorites and planets posit that they may have originated within the gas phase of the solar nebula which suggests the potential for correlations of non mass dependent oxygen isotopic anomalies with other chemical fractionations generated during cooling and condensation of the nebula we have examined three specific issues possible correlations of 17o with i oxidation state ii bulk chondrite chemistry and iii bulk planetary properties isolated grains and chondrules from several carbonaceous chondrite groups exhibit good to weak positive correlations between 17o and olivine fayalite content and whole rock ureilite samples show a positive correlation of 17o with olivine fayalite content these are consistent with oxidation of fe metal by 17o 18o enriched oxygen in the precursor materials that formed these objects in contrast oxygen isotopic and major element compositions of ferromagnesian phases in ordinary chondrite chondrules and in bulk chondrites do not show a correlation thus there is no compelling evidence that oxidation of nebular materials was tightly linked to gas species carrying anomalous o using average chondrite group compositions we demonstrate that significant negative correlations of refractory lithophile element mg and refractory siderophile element ni with 17o exist refractory inclusions cais and aoas are modally rare in many chondrite types that exhibit substantial range in 17o thus the refractory component in these chondrites must occur in a crypto component e g material dissolved in chondrule melts during chondrule formation significant positive correlations of moderately volatile elements mg with 17o are not simply explained by incomplete mixing of 16o enriched refractory grains but are broadly consistent with nebula based mechanisms of non mass dependent oxygen isotope fractionation the estimated compositions of the primitive mantles of the earth mars and 4 vesta have some compositional redox and isotopic properties that vary with heliocentric distance however 17o does not vary monotonically in this sequence indicating a decoupling of planetary o isotopic composition from other compositional characteristics

an integrated approach for the prediction of subsidence for coal mining basins abstract in this study land subsidence caused by underground mining activities was investigated by means of a new subsidence prediction approach isp tech which takes into account the most important parameters contributing subsidence development such as coal production methods depth mining sequence and other geomechanical characteristics of underground rock strata etc isp tech can be applied to operating mines to keep land subsidence under control as well as virgin coal sites to predict surface subsidence prior to mining activities in the method geological information gathered from the geographic information system gis and the mining information system mis are utilised to obtain geological cross sections which are used in finite element models for mesh building then a number of two dimensional finite element modelling analyses are carried out to determine land subsidence occurring due to mining operations finally land subsidence predicted from modelling studies is compared to the gps and or differential interferometry synthetic aperture radar din sar measurements if incompatibility of the results is detected finite element meshes should be optimised and then reanalysed to obtain more compatible results in the study two different case studies were given as examples of the application of isp tech results of the case studies showed that isp tech can successfully be applied to complex mine subsidence problems the proposed approach gives more accurate results than those obtained from other classical subsidence prediction methods

cosmic ray exposure ages of four acapulcoites and two differentiated achondrites and evidence for a two layer structure of the acapulcoite lodranite parent asteroid abstract we determined the he ne and ar isotopic abundances in the four acapulcoites dhofar dho 125 dho 290 dho 312 and graves nunataks 98028 the metal rich diogenite northwest africa nwa 1982 and a unique achondrite nwa 1058 that resembles the acapulcoites in its chemical composition the noble gases in these meteorites consist of three components trapped gases cosmic ray produced nuclides and nuclides produced by k th and u decay the four acapulcoites yield cosmic ray exposure cre ages in the range of 5 0 5 7 ma and confirm earlier conclusions concerning break up of all acapulcoites from a common s type parent asteroid possibly in three events 4 9 5 9 and 14 8 ma ago we also discuss the other characteristics mineralogy chemistry formation ages and oxygen and trapped noble gas isotopes of all other acapulcoites and their relatives the lodranites we propose that the acapulcoite lodranite parent asteroid had a shell structure similar to that of the h chondrites the less metamorphosed acapulcoites correspond to the h3 and h4 chondrites and originate from the exterior layers whereas the more severely metamorphosed lodranites similar to the h5 and h6 chondrites represent the inner regions of their parent body ungrouped achondrite nwa 1982 probably a diogenite shows a cre age of 18 9 2 0 ma that falls on the major exposure age cluster of the diogenites the unique achondrite nwa 1058 differs in cosmic ray exposure age 38 9 4 0 ma and in oxygen isotopic composition from the acapulcoites and lodranites and is probably a winonaite

analysis of developmental features and causes of the ground cracks induced by oversized working face mining in an aeolian sand area in order to satisfy the energy demand of china it is an effective way to exploit coal resources efficiently in western china when a coal seam with a shallow burial depth is mined on a large working face with width of 300 m in a semi desert aeolian sand area of western china the induced subsidence and damage of ground surface are remarkably different from those induced by a traditional mining condition by taking working face 12 406 of bulianta coalmine in shendong mining area as an example this paper based on actual measurement data analysed the developmental features and causes of ground surface racks research results showed that the shape of the static crack in the peripheral area on the working face was very similar to that contained in the actual measurement results of other areas specifically such static crack was arc shaped and the actually measured static crack angle was 84 5 however the dynamic crack above the working face took on uniqueness in two developmental cycles expansion to restoration this phenomenon is not available in other research areas starting from the structure of rock strata this paper analysed the two developmental cycles of dynamic cracks according to the periodic fracture theory of key stratum and verified the results of theoretical analysis by employing the similar material model

mining induced strata stress changes fractures and gas flow dynamics in multi seam longwall mining abstract this paper presents key findings from a recent comprehensive study of longwall mining induced strata movement stress changes fractures and gas flow dynamics in a deep underground coal mine in anhui china the study includes field monitoring of overburden displacement stress and water pressure changes at the longwall panel 1115 1 of the guqiao mine in addition 3d modelling of strata behaviour at the longwall panel using a 3d finite element code and goaf gas flow simulations with a cfd code are carried out this research has resulted in many new insights into the complex dynamic interaction between mining induced strata stress changes fractures and gas flow patterns based on the findings from the field monitoring and numerical modelling a three dimensional annular shaped overlying zone along the perimeter of the longwall panel is identified for optimal methane drainage during mining a practical method that helps define the geometry and boundary of this zone is proposed this study provides a new methodology and a set of engineering principles for the design of optimal co extraction of coal and methane

groundwater as an environmental constraint of longwall coal mining groundwater impacts are a common reason for opposition to longwall mining most impacts are due to subsidence related fracturing although upper aquifers are protected from drainage to the mine by a confining zone water levels decline due to fracture dilation and drawdown expands outward a few hundred meters recovery of water levels is common

disequilibrium partial melting experiments on the leedey l6 chondrite textural controls on melting processes a series of experiments were designed to investigate the textural and compositional changes that take place during disequilibrium partial melting of chondritic material chips of the l6 chondrite leedey were heated at 1200 degreesc and log fo 2 iw 1 for durations of 1 h to 21 days we observed a progression of kinetically controlled textural changes in melt and restite minerals and changes in the liquidus mineralogy in response to factors such as volatile loss during the course of the experiments both olivine and orthopyroxene recrystallized at different times rare relic chondrules could still be identified after 21 days the silicate melts that form are very heterogeneous in terms of both major and trace element chemistry reflecting heterogeneity of the localized mineral assemblage particularly with respect to phosphates and clinopyroxene metal sulfide melts formed in short duration runs are also heterogeneous the experimental data are relevant to aspects of the genesis of primitive achondrites such as the acapulcoites the observed textures are consistent with a model for acapulcoite petrogenesis in which silicate melting was limited to only a few volume percent of the chondritic source rock the experiments are also relevant to the behavior of chondritic material that has been partially melted in an impact environment

fe mg fe mn relations of meteorites and primary heterogeneity of primitive achondrite parent bodies abstract we examine fe mg mn relations of meteorites as represented on plots of molar fe mg ratio vs molar fe mn ratio and use them to consider whether it is meaningful to classify achondrites as primitive or evolved first we demonstrate that fe mg fe mn plots can be used to identify some of the major processes that have affected meteorite parent bodies during both the nebular condensation and accretion and the planetary igneous stages of their evolution examination of compositions of chondrites on this diagram reveals distinct patterns that result from three nebular processes 1 volatility controlled mn mg fractionation 2 metal silicate fractionation under highly reducing conditions and 3 subsequent oxidation leading to variations in feo mgo ratio ordinary chondrites ocs show a characteristic pattern that records all three of these processes and suggests that the latter two are coupled examination of the compositions of achondrites on this diagram shows that all of those that have been classified as primitive lodranites acapulcoites winonaites iab silicate inclusions brachinites and ureilites are easily distinguished from those that have been classified as evolved sncs heds and lunar basalts the mn mg ratios of the former are chondritic while those of the latter are superchondritic hence they plot in two graphically distinct regions of the fe mg fe mn diagram a simple melting calculation reveals that this distinction results principally because the former are residues and the latter are melts or cumulate products of melts rather than because the latter are more evolved additionally however some of the groups classified as primitive achondrites show fe mg fe mn patterns similar to that of ocs constant but distinct mno mgo ratios over large ranges of feo mgo ratio we argue that these trends reflect primary heterogeneity resulting from the same nebular processes as those that affected ocs and therefore preserve evidence that more of the materials that accreted to form planetesimals experienced these processes than is apparent from known chondrites this evidence is preserved principally because these meteorites are residues in contrast groups commonly classified as evolved achondrites show fe mg fe mn patterns that reflect only igneous processing and any evidence for primary heterogeneity of their parent bodies has been obliterated again this is principally because these meteorites represent melts rather than beause they are more evolved usage of the terms primitive and evolved to describe achondrites should be clearly defined

development law of air leakage fractures in shallow coal seams a case study in the shendong coalfield of china continuous air leakage from ground mining induced cracks is a significant cause of coal spontaneous combustion low oxygen at the working face and other disasters in shallow coal seams this paper studies mining induced cracks and air leakage caused by the repeated mining of shallow coal seams at the bulianta coal mine shendong coalfield china a similar simulation experiment was carried out in the laboratory and then the ground mining induced cracks were observed and the crack air leakage was detected the results showed that the surface air flowed into the composite goaf before the fractures redeveloped to the surface during the process of lower coal seam mining due to the different development processes of vertical fractures in various regions the width of the vertical fractures in the boundary area of the overlying goaf increases significantly after the repeated mining of coal seams while the vertical fractures in the central area of the overlying goaf experience almost no change the distribution of the surface air leakage cracks is in the shape of graben type cracks and half graben type cracks are surface air leakage cracks which are the focus of surface air leakage problems especially the half graben type cracks the results are important in engineering for reducing air leakage from surface mining induced cracks

prediction of subsidence due to coal mining in raniganj coalfield west bengal india abstract raniganj coalfield is in a major coal producing area and suffers subsidence problems due to underground mining the occurrence of a thick coal seam at shallow depth is the main reason for the subsidence and as a result collapses have occurred in many coal mines in recent years we attempt to predict the subsidence occurring in indian coalfields in general and in particular in the raniganj coalfield using a visco elastic model in this model we have considered the coal seam as a beam resting between visco elastic media which deform due to transverse shear after mining the governing equations have been solved for two cases coal mines with a rigid hard and b flexible soft overburdens the ground subsidence has been computed for two coal mines the computed subsidence profiles of the ratibati and shivadanga coal mines of the raniganj coalfield are compared and the results show a reasonable match between the predicted and observed subsidence in the case of ratibati coal mine in the case of shivadanga coal mine the predicted subsidence profile is found to be larger than the observed profile however the bottom of the observed troughs is found to match the predicted troughs detailed analyses have been carried out to investigate the effect of mine parameters on the subsidence

collisional modification of the acapulcoite lodranite parent body revealed by the iodine xenon system in lodranites the i xe system of three lodranites has been investigated samples of gibson yielded no isochrons and late model ages are attributed to late addition of iodine two metal and one silicate separate from the transitional lodranite graves nunataks gra 95209 gave ages that are consistent with each other and with the literature i xe age of acapulco feldspar these yield a mean closure age 4 19 0 53 ma after the shallowater enstatite reference age 4562 3 0 4 ma such identical i xe ages from distinct phases imply that the parent material underwent a period of rapid cooling the absolute age of this event being 4558 1 0 7 ma such rapid cooling indicates an increase in the rate at which heat could be conducted away requiring a significant modification of the parent body we suggest the parent body was modified by an impact at or close to the time recorded by the i xe system an age of 10 4 2 3 ma after shallowater has been determined for one whole rock sample of lewis cliff lew 88280 since the release pattern is similar to that of gra 95209 this hints that the larger grain size of this sample may reflect slower cooling due to deeper post impact burial

void fraction distribution in overburden disturbed by longwall mining of coal voids in overburden disturbed by coal mining provide channels for transfer of heat methane groundwater oxygen exhaust gas and fire fighting materials in the underground environment based on expressions of strata and ground subsidence a group of void fraction distribution models are proposed including porosity in the caved zone the fracture ratio in the bed separation zone and the fissure ratio in the ground subsidence zone combined with a case study of the antaibao coal mine china theoretical calculation and numerical simulation indicate that porosity distribution in the caved zone is u type and the transverse void fractions in the bed separation zone and ground subsidence zone have m type distributions additionally the longitudinal void fraction distribution changes from type to m type along the strike and dip of the coalbed after the complete subsidence of ground the distribution of fractures in the disturbed overburden of the goaf presents a fractured arch and fracture density gradually decreases from arch foot to crown fire prone zones propagating paths of coalbed fires areas prone to water influx and outlets of boreholes used for fire fighting all usually appear around the perimeter of disturbed overburden the transverse void fractions distribution in the bed separation zone changes from type to m type with an increase in the size of the goaf it is suggested that the inlets of gob vent boreholes should be arranged near the center of the bed separation zone in the early stages of longwall mining and around the perimeter in middle to late stages of mining

numerical modeling for analyzing thermal surface anomalies induced by underground coal fires abstract coal seams burning underneath the surface are recognized all over the world and have drawn increasing public attention in the past years frequently such fires are analyzed by detecting anomalies like increased exhaust gas concentrations and soil temperatures at the surface a proper analysis presumes the understanding of involved processes which determine the spatial distribution and dynamic behavior of the anomalies in this paper we explain the relevance of mechanical and energy transport processes with respect to the occurrence of temperature anomalies at the surface two approaches are presented aiming to obtain insight into the underground coal fire situation in situ temperature mapping and numerical simulation in 2000 to 2005 annual temperature mapping in the wuda inner mongolia pr china coal fire area showed that most thermal anomalies on the surface are closely related to fractures where hot exhaust gases from the coal fire are released those fractures develop due to rock mechanical failure after volume reduction in the seams the measured signals at the surface are therefore strongly affected by mechanical processes more insight into causes and effects of involved energy transport processes is obtained by numerical simulation of the dynamic behavior of coal fires simulations show the inter relation between release and transport of thermal energy in and around underground coal fires our simulation results show a time delay between the coal fire propagation and the observed appearance of the surface temperature signal additionally the overall energy flux away from the burning coal seam into the surrounding bedrock is about 30 times higher than the flux through the surface this is of particular importance for an estimation of the energy released based on surface temperature measurements finally the simulation results also prove that a fire propagation rate estimated from the interpretation of surface anomalies can differ from the actual rate in the seam

allan hills 77081 an unusual stony meteorite abstract allan hills alha 77081 is achondritic in texture while the mineral composition and the chemistry are chondritic with the exception of a few elements an assignment to one specific group of ordinary chondrites is therefore difficult in many respects this meteorite is similar to the unusual stone meteorite acapulco the ree pattern of alha 77081 is essentially flat and the distribution ratios of siderophile elements between metal and silicates are high compared to ordinary chondrites gas retention ages are 3 5 0 5 ae for u th he and 4 50 0 15 ae for k ar in spite of the high degree of recrystallisation the meteorite contains trapped noble gases in amounts comparable to type 4 chondrites cosmic ray tracks and spallogenic noble gases indicate a small preatmospheric radius of about 2 3 cm spallogenic nuclides produced by solar cosmic rays or stopped solar flare ions may be present

dating of coal fires in xinjiang north west china coal fires in china consume vast amounts of fuel and cause serious environmental problems most of these coal fires are related to mining activity however naturally produced palaeo coal fires in xinjiang north west china have been recognized via burnt rocks the burnt rocks in the study area are found at different river terraces underlying unburnt alluvial and river terrace deposits several age groups of coal fires have been identified based on the positions of burnt rocks at river terraces and the relationship between the burnt rocks and the terrace

a zoning model for coal mining induced strata movement based on microseismic monitoring a microseismic monitoring technique is adopted to investigate the distribution regularity of microseismic events released by the coal mining induced roof rock mass along the vertical and horizontal directions in combination with mine geological data on the basis of the quantity and energy distributions of the microseismic events recorded using the microseismic monitoring technique a zoning method is first established for the roof strata movement in the vertical and horizontal directions the vertically zoning method is then applied to analyze the microseismic monitoring results obtained in the dongjiahe coal mine which divides rock mass into six zones along the vertical direction i e the caved zone the block zone the vertical fracture through going zone the vertical fracture zone the separation zone and the continuous zone the horizontally zoning model divides the roof strata movement into three zones i e the calm zone the generation zone impacted by working face and the historical generation zone after that based on the horizontally zoning model a method is developed to determine the displacement angle using the microseismic monitoring data which has been verified in the dongjiahe coal mine

analysis of coal fire dynamics in the wuda syncline impacted by fire fighting activities based on in situ observations and landsat 8 remote sensing data abstract coal fires are a global catastrophe for valuable coal resources the environment human health and safety fire fighting activities are the approach to limit these catastrophic influences and to extinguish active coal fires the wuda syncline in inner mongolia is one of the biggest coalfields suffering from coal fires in china and is one of the coalfire areas globally which has been analyzed most comprehensively massive fire fighting activities have been undertaken to quench coal fires in the wuda syncline particularly activities such as blasting and excavation have accelerated since the year 2010 influence of fire fighting activities on coal fire dynamics is a significant topic but has rarely been reported yet although airborne and spaceborne earth observation data holds the potential to monitor extinguishing activities this data is rarely applied for this purpose airborne thermal scanner data is cost intensive to fly and spaceborne landsat 7 scanner system with a thermal band at 60 m spatial resolution in 2003 led to a limited exploitation of this valuable data source just recently landsat 8 satellite data with a thermal infrared band of 100 m spatial resolution is available since early 2013 and is able to fill this gap we conducted in depth in situ surveys on coal fires and fire fighting activities in the wuda syncline in may 2014 after visiting the wuda coalfield in 2012 we integrated our in situ observations and thermal anomalies extracted from both landsat 8 and landsat 7 slc on acquired before the scanner failure satellite data using an automated moving window thermal anomaly extractor regional anomaly extractor rae and analyzed coal fire dynamics impacted by fire fighting activities and the state of coal fires in the wuda syncline results show that after over 4 years of efforts to fight against coal fires in the wuda syncline the nos 1 7 no 9 no 12 and no 13 coal fire zones are extinct however the no 8 no 10 no 11 and no 14 no 18 coal fire zones are still active and furthermore three novel coal fire zones have evolved in the light of in situ surveys in the wuda coalfield these active and newly developed coal fires are mainly attributed to extinguishing related activities such as the blasting and excavation in fire affected areas which lead to the exposure of pure coal seams weathered coal pillars and coal waste piles to the outside air the contact of this coal and coal remnants with oxygen triggers spontaneous combustion of coal and further develops to coal fires additionally time series analyses of extracted thermal anomalies suggest that coal fires propagate eastward according with the dip direction of coal seams in the wuda coalfield the regional thermal anomaly extraction tool rae can delineate thermal anomalies with a high accuracy which is confirmed by our in situ surveys this paper is the first investigation on dozens of landsat satellite images to evaluate the state of coal fires within one year which is more accurate compared to previous approaches analyzing merely one or several satellite images to assess the state of coal fires during one year period

simulating mining induced strata permeability changes abstract mining processes fracture the surrounding strata and may modify the flow of groundwater by inducing new fractures or changing the permeability of existing defects the result of mining induced permeability changes can be disturbance to aquifers or other surface or sub surface water bodies traditional methods for predicting mining induced fracture connectivity and enhanced permeability based on empirical strain based criteria may not satisfy modern regulatory demands nor adequately reflect local geological geotechnical and hydrogeological conditions standard continuum numerical methods may indirectly estimate permeability enhancement from plastic strains however they are not able to track aperture on flow paths or predict fracture connectivity this paper presents a numerical approach that is demonstrated to be capable of representing longwall mining induced fracturing in sedimentary rock masses by initiating and propagating fractures determining connectivity and calculating aperture in a piecewise manner on flow paths we have estimated permeability enhancement from first principles fracture intensity and porosity metrics are calculated and identify the height of the enhanced permeability fractured zone above a longwall goaf permeability within the overburden is estimated from the kozeny carman permeability porosity equation at a mine site studied in detail in this paper a permeability increase from the in situ state is predicted to range from approximately eight orders of magnitude in the caved zone to one to two orders of magnitude in the strata above the fractured zone realistically simulating cracking fracturing and crushing of rock strata remains numerically intensive and challenging at the scale of a longwall panel it is demonstrated in this paper and provides valuable insights into the rockmass response to mining

a new method of analysis of water level response to a moving boundary of a longwall mine longwall coal mining is an economical method for coal extraction that allows most of the coal to be extracted from a wide rectangular panel the roof of the working face area is temporarily held up by supports which advance as the mine face advances a basin like subsidence trough develops at the ground surface over the panel as the panel roof behind the supports collapses a dynamic subsidence front causes a water level drop at wells ahead of the panel we examine the effects of subsidence on water level by introducing a sink that moves with the mining face using the one dimensional flow equation to test the validity of this method we estimated aquifer parameters of trivoli sandstone aquifer over a longwall coal mine in the illinois basin by analyzing water level versus time data measured from three observation wells the presented method predicts a value of transmissivity and storage coefficient that is reasonably close to the average of pumping test results with this method we provide solutions to two significant problems 1 presubs 2 water level drops can be predicted for a planned longwall mine if the aquifer parameters are known

a petrologic chemical and isotopic study of monument draw and comparison with other acapulcoites evidence for formation by incipient partial melting abstract we have conducted petrologic chemical and isotopic studies of acapulcoites acapulco monument draw yamato 74063 alh a77081 alh a81261 alh a81315 alh 78230 alh a81187 and alh 84190 in an attempt to constrain their genesis acapulcoites have distinctly different oxygen isotopic compositions than silicate inclusions in iab and iiicd irons winonaites and ureilites and thus formed on a different parent body oxygen isotopic compositions which are slightly heterogeneous within the group overlap with lodranites indicating a likely origin on a common parent body these groups can be distinguished on the basis of mafic silicate grain size all acapulcoites have mafic silicate compositions intermediate between e and h chondrites roughly chondritic mineralogies achondritic equigranular textures micrometer to centimeter sized veins of fe ni fes which cross cut silicate phases rapid metallographic cooling rates at 600 400 c 103 105 c myr and trapped noble gas abundances comparable to type 3 4 ordinary chondrites they exhibit variable mafic silicate zoning abundance of fe ni fes veins ree abundances and patterns and possibly cosmic ray exposure ages 5 7 ma momument draw and yamato 74063 retain rare relict chondrules phosphates are associated with fe ni fes veins or form separate veins in monument draw and acapulco heating and cooling of acapulcoites occurred very early in the history of the solar system as evidenced by the 39ar 40ar ages of 4 51 ga these ages appear distinctly younger than the likely formation time for acapulco of 4 557 ga but are older than analogous 39ar 40ar ages for most chondrites acapulcoites formed from a precursor chondrite which differs from known chondrites in mineral and oxygen isotopic compositions heating to 950 1000 c resulted in melting at the fe ni fes cotectic but silicates did not melt silicate textures resulted from extensive solid state recrystallization heating was by noncollisional sources e g 26al electromagnetic induction despite uncertainties owing to a lack of data acapulcoites may have experienced a three stage thermal history of slow cooling at high temperature rapid cooling at intermediate temperatures and slow cooling at low temperatures possibly resulting from breakup and gravitational reassembly of the parent body the complex thermal history is also reflected in disequilibrium ree abundances one or at most two impact events 7 ma and possibly 5 ma ago are consistent with the cosmic ray exposure ages of all four acapulcoites for which cosmogenic noble gas data exist

the cooling history of the acapulco meteorite as recorded by the 244pu and 40ar 39ar chronometers 244pu fission track densities recorded in phosphates merrillite and apatite and in orthopyroxenes adjacent to phosphates along with 40ar 39ar dating were used to retrace the cooling evolution in the low temperature regime of the acapulco meteorite over a time interval of 110 ma high resolution 40ar 39ar dating yielded a plateau age of 4514 16 ma and a precise 40ar closure temperature of 560 20 k in plagioclase this ar closure temperature is essentially indistinguishable from the 50 retention temperature of fission tracks registered in orthopyroxene 550 25 k this allows us to anchor the floating relative 244pu timescale to the absolute timescale defined by the 40ar 39ar chronometer plutonium contents of bulk phosphates inferred from fission xenon are 2x higher than those inferred from tracks in the same phosphates reflecting the low track retention temperatures of phosphates however the pu contents from tracks in orthopyroxenes adjacent to phosphates agree with those from fission xenon suggesting similar retention temperatures and times our results together with an estimated peak metamorphic temperature 1300 k and the u pbpb datum of acapulco phosphates gopel et al 1992 outline an early thermochronological history of acapulco that is more detailed than obtained by earlier attempts and spans a time of 160 ma fast cooling in the high temperature regime 1300 720 k of 100 40 k ma was followed by a drastic change of the cooling rate between 720 and 560 k 3 7 k ma down to a very slow cooling 1 7 0 5 k ma from 550 to 360 k the fast cooling at high temperatures shared also by other acapulcoite lodranites a l suggests that the parent body of acapulco was distinctly smaller than the h chondrite asteroid in contrast the very slow cooling in the low temperature regime should imply that acapulco like material became effectively insulated during a later stage of its history 6 ma after the asteroid formation if a formation time of 4565 ma is assumed for the a l body extrapolations back in time of the pu contents of phosphates give initial 244pu 238u ratios of 0 4 10 2 and 11 10 2 for apatite and merrillite respectively for the bulk phosphates an initial pu u value of 0 8 0 16 10 2 is obtained for acapulco which is in full agreement with the preferred chondritic ratio of 0 7 10 2 proposed by hagee et al 1990 trapped ar contents are surprisingly high both primordial 36ar at levels of type 4 ordinary chondrites and excess radiogenic 40ar were detected in our sample as in some acapulcoites by other authors this partial closed system behaviour could be the result of the partial melt and sintering effects that the high peak metamorphic temperatures have induced in a l meteorites in addition the spread in the early peak temperatures 1300 1450 k as reflected by the diverse degrees of partial melting observed in a l meteorites suggests heterogeneously distributed short lived heating sources 26al60fe and disfavours the homogeneous heating expected from an electromagnetic induction arising from an active pre main sequence sun the possibility that some specific collisional event s with or without disruption of the a l planetesimal could satisfactorily explain the thermal histories and diverse characteristics of these meteorites appears difficult to envision in the absence of evident shock effects in most if not all a l meteorites

brachina a new type of meteorite not a chassignite the brachina meteorite previously classified as a chassignite is found to be a nearly primitive and unique meteorite it is a fine grained unshocked equigranular igneous rock containing small melt inclusions it contains 80 olivine fo70 5 5 clinopyroxene wo38en49fs13 10 plagioclase an22 0 5 chromite 0 5 chlorapatite 3 fe sulfide 0 3 pentlandite and a trace of ni rich metal orthopyroxene en70 and anorthoclase rich glass are found only in melt inclusions siderophiles are high in the sulfides and the oxidation state is similar to that of ll chondrites major element and mineralogic data of brachina are similar to chassigny but trace element data are dramatically different the major differences are higher feo mno ga al and k la ratios w depletion high siderophile content near horizontal ree pattern at about 1 chondrite level high refractory nonrefractory metal ratios e g ir au and chalcophile element depletion compositionally brachina is close to c2 chemistry but has undergone some segregation of fe ni s melt these data in addition to its near 4 5 b y age and oxygen isotopic signature within the eucritic field suggest that brachina is not related to chassigny or snc meteorites it may be related to primitive meteorites such as silicate inclusions in iab irons and winonaites but is more oxidized reduction would make it very similar to winonaites the assemblage may have experienced the beginning of melting in its parent body since it has characteristics that differ from any other meteorite we suggest it be called a brachinite

investigation of fill distribution in post injected longwall overburden with implications for grout take estimation abstract in civil and mining engineering grout injection technology which involves the injection of grout into the bedding separation zone or other voids through surface boreholes is used to stabilize the ground above underground excavations the injected fill at the targeted void space mitigates the deformation of overlying strata thus reducing surface subsidence when applying this technology it is important to determine the distribution of the injected fill in the overburden as it affects grout take estimation evaluation of subsidence control effectiveness etc in this paper we present theoretical and physical models of the distribution of the injected fill according to previous borehole data the location of the injected fill is assumed to be a single horizon based on the characteristic of the main injection horizon and geological features of the surrounding strata an easy to use theoretical model of injected fill distribution is proposed which quantifies the fill thickness at different locations along the main injection horizon the proposed model is verified using a physical model of overburden grout injection in addition to the injection parameters such as the horizon depth and ratio of injection a site specific geological parameter namely the angle of full subsidence as well as the underground opening width play a vital role in governing the fill distribution using the proposed model we develop a method for estimation of grout take which may facilitate the injection design thus improving the effectiveness of ground stabilization

low temperature thermochronology of the carlin type gold deposits in southwestern guizhou china implications for mineralization age and geological thermal events abstract the dian qian gui area in southwestern china is the second largest concentration of the carlin type gold deposits in the world and the southwestern guizhou is the most important gold producing district of the dian qian gui area dating of the carlin type gold deposits is always a challenge due to the lack of ore stage minerals which are suitable for conventional radiometric dating low temperature thermochronometers including fission track and u th he are temperature sensitive radiometric dating techniques and have been successfully applied to elucidate many aspects of ore deposits including the timing and duration of mineralization processes in this study zircon fission track zircon u th he and apatite fission track dating techniques were applied to the carlin type gold deposits in southwestern guizhou samples for zircon and apatite analyses were collected from mineralized or altered sedimentary rocks in shuiyindong taipingdong bojitian yata and getang gold deposits four groups of thermochronological ages were obtained i e 192 216 ma 132 160 ma 88 ma and 19 40 ma which are considered to be the records of four geological thermal events of them most zircon fission track ages and all zircon u th he ages concentrate in 132 160 ma thermochronological constraints combined with field relationships suggest that the mineralization of the carlin type gold deposits in southwestern guizhou most likely occurred in this period partial zircon fission track ages are in 192 216 ma they may record the cooling timing of a pre ore thermal event caused by the indosinian orogeny which is supported by the paleogeotemperature restoration a few zircon grains with high u content yield fission track age of 88 ma which may record a post ore thermal event associated with the intrusion of local mafic dykes all apatite fission track ages range in 19 40 ma which may record a lower temperature but extensive hydrothermal superimposition in the cenozoic additionally a corresponding relationship between zircon fission track ages and stratigraphic sequences was identified in the huijiabao anticline which is considered to reflect the decrease of temperature and duration of ore forming hydrothermal activity from lower to upper stratigraphic sequences

soil and water conservation in mining area based on ground surface subsidence control development of a high water swelling material and its application in backfilling mining it has always been a crucial issue in the mining industry that the surface subsidence induced by underground coal mining can lead to the severe deterioration or loss of soil and water resources in mining area backfilling has become one of the most frequently used mining method to solve this puzzle as it can effectively control the movement of overlying strata and therefore soil and water resources will not be destroyed by mining activities a new type of high water swelling material hwsm was developed to address the key issues of current backfilling materials used in collieries such as the high cost inadequate strength and low expansion rate based on the principle that the strength of backfilling body satisfies the requirement a critical ratio of water to solid material a mixture of fly ash which was used as an aggregate lime anhydrite cement and additive ingredients was determined which varied from 0 8 1 to 0 9 1 meanwhile the mass ratio of fly ash anhydrite lime cement and additives was determined to be 24 6 0 8 5 1 1 8 1 laboratory tests showed that strength of samples that met the required setting time for practical use could reach 5 39 5 52 mpa after 63 days the expansion rate after 3 h varied between 9 9 and 10 8 and the bleeding rate ranged from 0 3 to 0 33 industrial application has been conducted in wangtaipu colliery and results showed that the proposed hwsm had an outstanding mechanical performance with good expansion rates and fluidity these properties indicate that the developed material is suitable for use as a good backfilling material in mining so as to effectively reduce the ground surface subsidence and to conserve the soil and water

premine study of shallow coal seams using high resolution seismic reflection methods geological investigations in the illinois basin coalfields have shown that significant differences in safe and economical exploitation of coal depends directly on accurate mapping of the roof rock overlying the seam as well as on geological structures in the coal measures in roof rock transition zones above the herrin no 6 coal where the nonmarine energy shale changes to the anna shale a change often occurs from low to high sulfur coal and from low to high stability roof rocks in many instances use of borehole data alone is inadequate to locate these features in advance of mining high resolution seismic reflection data collected near harco illinois were used as part of premine planning to help predict roof instability areas of low sulfur coal and geologic disturbances several faults channels and facies changes affecting the herrin no 6 and the springfield no 5 coal seams at depths of 137 m and 167 m respectively were interpreted and modeled one and two dimensional synthetic seismo

partial melting and melt migration in the acapulcoite lodranite parent body we review petrologic evidence that the acapulcoites and lodranites formed by 1 vol to probably 20 vol whole rock partial melting of a chondritic precursor material at low degrees of partial melting only fe ni fes cotectic melting occurred migration distances for partial melts were short resulting in the formation of acapulcoites with essentially chondritic troilite and plagioclase contents but achondritic textures at high degrees of partial melting both fe ni fes and basaltic plagioclase pyroxene partial melts formed and the melts may have migrated out of the source rock the partial melt residues which are more or less depleted in fe ni fes and plagioclase are the lodranites melt migration was complex most acapulcoites which experienced relatively low degrees of partial melting lost little if any of the partial melt one acapulcoite lew 86220 represents a unique case in which fe ni fes and basaltic partial melts appear to have migrated from a lodranite source region into a cooler acapulcoite region where they were trapped in cases of the relatively high degrees of partial melting experienced by lodranites melts may have been partly selectively or totally removed from the rocks and fe ni fes and or basaltic partial melts may have been removed to different degrees and may in fact have been trapped on occasion in greater than chondritic proportions we model vein and dike formation and melt migration by calculating the excess pressures and vein and dike sizes for varying degrees of partial melting our calculations are broadly consistent with observations indicating that melt migration is inefficient at low degrees of partial melting and extremely efficient at high degrees of partial melting although the size of the acapulcoite lodranite parent body and the volatile contents of the chondritic precursor rocks are poorly constrained the lack of basaltic rocks in the world s meteorite collections complementary to the lodranites suggests that basaltic partial melts may have been accelerated off the body by explosive volcanism of the type envisioned by wilson and keil 1991 and ejected into space the diversity of rocks from the acapulcoite lodranite parent body may provide a basis for better understanding the diverse range of spectral subtypes recognized among the s type asteroids

carlisle lakes and allan hills 85151 members of a new chondrite grouplet carlisle lakes and allan hills 85151 alh85151 are members of a new grouplet of chondrites characterized by feo rich silicates olivine fa 38 41 mol unusual oxygen isotopic composition and abundant 35 vol recrystallized matrix material yamato 75302 is not as well characterized but is probably also a member of this grouplet siderophile elements in carlisle lakes and alh85151 are fractionated relative to ci chondrites refractory and common siderophiles are at 1 ci ga and as are lower 0 6 0 9 ci and au is very low 0 17 ci and 0 36 ci in carlisle lakes and alh85151 respectively the low au abundance may indicate that au resided mainly in fine grained metal particles that were suspended in the nebular gas during the time these chondrites agglomerated the oxidation state of chondrites may be controlled by the presence of oxidizing agents e g magnetite in agglomerated matrix material the high matrix abundance that characterizes this new grouplet may thus be responsible for the high oxidation state of these meteorites

investigation of movement and damage of integral overburden during shallow coal seam mining abstract most prediction methods used to calculate mining induced subsidence are empirical which cannot explain the mechanism of fundamental rock strata movement in this paper based on key stratum theory and the mechanical analysis of overburden a new analytical solution the analogous hyperbola subsidence model ahsm was proposed to describe the movement and damage of inner burden mining induced rock strata movement was verified using the distinct element method udec to assess the performance of the theoretical model three subsidence parameters smax t sgoaf smax d h generally used to describe surface subsidence trough agree with statistical field measurements of the south coalfield in australia the surface subsidence and the movement boundary in the overburden are very close to the theoretical predictions additionally the primary key stratum damages the least in the overlying strata its broken length is the smallest the width of subsidence trough and maximum surface subsidence increase as the primary key stratum drops

spectral reflectance 400 2500 nm properties of coals adjacent sediments metamorphic and pyrometamorphic rocks in coal fire areas a case study of wuda coalfield and its surrounding areas northern china abstract although remote sensing is an effective tool extensively employed to detect and monitor coal fires continuous spectral reflectance properties of typical land surfaces such as coals adjacent sediments metamorphic rocks and pyrometamorphic rocks in coal fire regions have not been reported yet field and laboratory spectral reflectance of coals bituminous anthracite and coal waste sediments rocks sandstones siltstone desert sands limestones and shale metamorphic and pyrometamorphic rocks located in wuda coalfield and its surrounding areas are investigated for the reflective domain ranging from 400 nm to 2500 nm the results indicate that coal depicts the lowest reflectance 2 10 and strong absorption bands between 2200 and 2500 nm resulting from organic matter pyrometamorphic rocks are characterized by weak absorption features at 1400 and 1900 nm due to partial dehydration and strong ferric absorption features between 850 and 1100 nm attributed to thermal alteration and oxidation of the rocks sediments exhibit common absorptions features at 2200 and 2300 nm probably related to al oh vibrations and carbonate degenerate c o vibrations respectively spectral reflectance increases with a decrease of the coal rank and particle size the investigations on spectral reflectance properties of typical land surfaces in coal fire regions provide the basic understanding for applications of hyperspectral or multispectral remote sensing to classify land covers and to demarcate coal fire risk areas in similar geological settings

surface collapse control under thick unconsolidated layers by backfilling strip mining in coal mines abstract surface subsidence induced by mineral extraction from underground mines can significantly affect the ecological environment and human life surface collapse is extremely hazardous and typically occurs without warning in china numerous surface collapses have occurred during mining operations in coal mines located under thick unconsolidated layers via analysis of the stability of the bearing structure arch structure in unconsolidated layers and key strata in rock strata based on their effects on strata movement our study reveals the formation mechanism of surface collapses and the roles played by two critical parameters mining length and mining height it is speculated that the bearing structure cannot be self stable and will collapse during longwall mining with increasing mining length and mining height as a result the ground surface will collapse on the longwall face gob accompanied by the failure of the bearing structure with these risks in mind this study proposes a backfilling strip mining method via determination of the appropriate longwall face length and mining height to guard against bearing structure failure and thus avoid surface collapse a field trial of the technique was conducted at a suitable chinese coal mine located under thick unconsolidated layers the maximum surface subsidence observed was only 0 369 m which is 92 less than the subsidence in longwall face lw 3a04 no surface collapse occurred during the mining process thus our results indicate that the proposed technique can successfully prevent surface collapse during longwall mining under thick unconsolidated layers

surface stepped subsidence related to top coal caving longwall mining of extremely thick coal seam under shallow cover the surface stepped subsidence had badly affected the public infrastructure safety the formation mechanism of the surface stepped subsidence case was explained the surface subsidence profile after the sequent mining activity was predicted the possible controls of the stepped subsidence were lastly proposed

the monitoring and prediction of mining subsidence in the amaga angelopolis venecia and bolombolo regions antioquia colombia abstract amaga angelopolis venecia and bolombolo are small towns located in antioquia in the central cordillera of the colombian andes mining has been practised in this region for a period of at least 100 years this mining has mainly been small scale poorly mechanised and restricted to shallow room and pillar workings recently the semi mechanisation of some mines has enabled coal to be extracted using longwall mining methods however this has resulted in subsidence that has caused severe damage to structures residential property and agricultural land and also induced landslides in the british isles there are several reliable methods that can be used to predict the likelihood and magnitude of mining subsidence the british coal corporation and the university of nottingham have developed one such method the subsidence with influence function technique swift based on mining subsidence observations undertaken in the coalfields of britain over a period of approximately 50 years the swift program was used to predict the magnitude of subsidence above a longwall panel at the industrial hullera mine in colombia the results were then compared with subsidence profiles obtained from precise levelling and field monitoring in each case the swift program overestimated the magnitude of mining subsidence by 0 17 0 20 m however the morphology of the subsidence profile area of influence and location of maximum subsidence were similar this overestimation of the predicted subsidence was attributed to the occurrence of strong igneous rocks such as rhyolite sills in the colombian coal measures these strong competent horizons act as cantilever beams during subsidence causing bed separation and therefore reducing the magnitude of subsidence in spite of these differences mining subsidence can be predicted with a reasonable degree of accuracy and precision using the swift technique provided the software is calibrated and used in conjunction with local expertise

oxidatively and thermally altered high volatile bituminous coals in high temperature coal fire zone no 8 of the wuda coalfield north china abstract coal fires have received increasing attention due to their environmental economic and social impacts their significant influence on coal properties is widely documented by geophysical and geochemical methods the present paper demonstrates by means of coal petrological methods significant changes of microstructure optical appearance and optical properties of medium rank bituminous coals affected by an underground coal fire the studied changes are suggested to result from distinct oxidative and thermal alterations induced by a high temperature regime temperatures over 800 c encountered in the coal fire zone no 8 wuda coalfield the investigated coal seam no 9 represents a high volatile a bituminous coal and is dominated by vitrinite followed by inertinite with minor amounts of liptinite the microstructure of the coal fire affected coals facilitate a broad spectrum of characteristic features the microscopic analyses revealed development of 1 non tectonic fissures and non tectonic fractures 2 distinct micropores 3 dark oxidations rims and 4 bright spots interpreted as incipient mesophases optical properties were characterised for megasporinite and vitrinite in the examined megasporinite a noticeable anisotropy and distinct granular appearance was observed in the investigated coals both a dominant increase as well as a minor decrease in both random and maximum vitrinite reflectances were documented for 1 coal grains and 2 dark rimmed vitrinite at non tectonic fissures and non tectonic fractures in addition also a characteristic bimodal vitrinite population was measured the increase in bireflectance was clearly documented for two sub zones within the coal fire zone no 8 the applied kilby s cross plots suggested a large overlapping of the data sets of r max and r min indicating marked changes in vitrinite structure the applied coal petrological approach revealed distinct changes to the coal s microstructure appearance as well as to optical properties induced by the underground coal fire the presented coal petrographic approach may help determine the extent of coal fires in coal mines and the direction of propagation of coal fire front

coal fires revisited the wuda coal field in the aftermath of extensive coal fire research and accelerating extinguishing activities abstract the wuda coal mining area in inner mongolia autonomous region china is one of the largest coal fire areas world wide at the same time it is also one of the most extensively researched ones the sub surface coal fires raging in the underground coal seams of the syncline are located directly west of the town of wuda the fires have been mapped in situ based on remote sensing data as well as based on geo physical survey all throughout the years 2001 to 2005 numerous publications depict the situation during that time in the present study we assess the current situation in wuda coal field five years after the last field campaigns under nowadays on going and accelerating extinguishing activities we present the results of coal fire dynamics assessment based on in situ mappings between 2004 and 2010 the analyses of changes in mining infrastructure between 2005 and 2012 as well as land cover change in the area from 2005 to 2012 newest high resolution multispectral and panchromatic quickbird data as well as time series of quickbird data supported this endeavor we furthermore present the result of semi structured interviews undertaken with members of the local mine directorate of the wuda syncline all jointly analyzed data indicate that the wuda coal fires tend to move eastwards within the syncline meaning that they move along the dip of the coal seams to greater depths furthermore mining related infrastructure is clearly moving from the west to the east as well despite large funds spent on fire extinguishing only few fires remain permanently extinct while other fire areas increase in size the former land cover structure in the arid syncline does not exist anymore extinguishing activities have led to a complete turn over of all material in the region the coal fire problem in wuda area remains a pressing one

coal fires in indonesia abstract indonesia s fire and haze problem is increasingly being ascribed to large scale forest conversion and land clearing activities making way for pulpwood rubber and oil palm plantations fire is the cheapest tool available to small holders and plantation owners to reduce vegetation cover and prepare and fertilize extremely poor soils fires that escaped from agricultural burns have ravaged east kalimantan forests on the island of borneo during extreme drought periods in 1982 1983 1987 1991 1994 and 1997 1998 estimates based on satellite data and ground observations are that more than five million hectares were burned in east kalimantan during the 1997 1998 dry season not only were the economic losses and ecological damage from these surface fires enormous they ignited coal seams exposed at the ground surface along their outcrops coal fires now threaten indonesia s shrinking ecological resources in kutai national park and sungai wain nature reserve sungai wain has one of the last areas of unburned primary rainforest in the balikpapan samarinda area with an extremely rich biodiversity although fires in 1997 1998 damaged nearly 50 of this reserve and ignited 76 coal fires it remains the most valuable water catchment area in the region and it has been used as a reintroduction site for the endangered orangutan the office of surface mining provided indonesia with the capability to take quick action on coal fires that presented threats to public health and safety infrastructure or the environment the us department of state s southeast asia environmental protection initiative through the us agency for international development funded the project technical assistance and training transferred skills in coal fire management through the ministry of energy and mineral resource s training agency to the regional offices giving the regions the long term capability to manage coal fires funding was also included to extinguish coal fires as demonstrations to the indonesian government successful demonstrations obtained visible benefits for a large number of local interests and received overwhelmingly favorable public response this built the public and political support needed to continue this work these successes encouraged the ministry to officially assume the responsibility for coal fire management by decree 1539 20 mpe 1999 the ministry reallocated internal funds to support portions of the immediate suppression projects and committed a portion of the coal royalty fund to provide long term support for coal fire suppression activities coal fires continue to present a serious risk to indonesia s ecosystems population and forest resources the ministry and local governments in east kalimantan are still working on the coal fire inventory it presently contains 164 coal fires but it is far from complete unless these coal fires are managed or extinguished they will add to the already catastrophic cycle of anthropogenic forest fires that further reduce indonesia s forest resources and endangered species while contributing unnecessarily to global carbon emissions

petrogenesis of acapulcoites and lodranites a shock melting model abstract acapulcoites are modeled as having formed by shock melting cr like carbonaceous chondrite precursors the degree of melting of some acapulcoites was low enough to allow the preservation of 3 6 vol relict chondrules shock effects in acapulcoites include veins of metallic fe ni and troilite polycrystalline kamacite fine grained metal troilite assemblages metallic cu and irregularly shaped troilite grains within metallic fe ni while at elevated temperatures acapulcoites experienced appreciable reduction because graphite is present in some acapulcoites and lodranites it seems likely that carbon was the principal reducing agent reduction is responsible for the low contents of olivine fa 4 14 mol and low ca pyroxene fs 3 13 mol in the acapulcoites the observation that in more than two thirds of the acapulcoites the fa value is lower than the fs value in contrast to the case for equilibrated ordinary chondrites the low feo mno ratios in acapulcoite olivine 16 18 compared to 32 38 in equilibrated h chondrites the relatively high modal orthopyroxene olivine ratios e g 1 7 in monument draw compared to 0 74 in h chondrites and reverse zoning in some mafic silicate grains lodranites formed in a similar manner to acapulcoites but suffered more extensive heating loss of plagioclase and loss of an fe ni s melt acapulcoites and lodranites experienced moderate post shock annealing presumably resulting from burial beneath material of low thermal diffusivity the annealing process repaired damaged olivine crystal lattices lending acapulcoites and lodranites the appearance of unshocked i e shock stage s1 rocks any high pressure phases that may have formed during initial shock reverted to their low pressure polymorphs during annealing some samples were subsequently shocked again several acapulcoites reached shock stage s2 levels alh 84190 reached s3 and the lodranite mac 88177 reached s5

application and effects of singularity analysis in evaluating the denudation degree of carlin type gold deposits in southwest guizhou china abstract denudation is a critical factor controlling the post ore change and preservation of deposits and the study of the degree of post ore denudation is a common practice in mineral exploration this paper introduces the use of singularity analysis and its efficacy in evaluating the degree of denudation of carlin type gold deposits in southwest guizhou the paper specifically focuses on investigating the geological effects before and after the introduction of the singularity analysis compared to the results obtained by means of the element concentration contrast the results of the singularity analysis effectively estimate the relative degrees of denudation of the deposits and ore fields in addition the results also accord well with findings from studies of the geology of ore deposits the geochemical primary halo and the apatite fission track these outcomes suggest that using singularity analysis to determine the degree of denudation can yield significant geological information and support accurate interpretation of the data thus the evaluation results based on such analysis have a higher reference value for expanding the understanding of post ore deformation of deposits and exploring unexposed orebodies in southwest guizhou

impact melt products of chondritic material a large variety of objects in chondritic meteorites formed as a result of impact melting shock veins metal troilite mixtures metal and sulfide nodules melt pockets vugs agglutinates glassy and crystalline spherules and numerous types of melt rock clasts the type of object produced in an impact event is related to the interaction of the shock waves with the particular target rock impact melting has also affected large portions of several chondrite breccias many of these contain vugs and patches of silicate glass some workers have suggested that various iron meteorites including groups iab iiicd and iie as well as several ungrouped irons were formed from individual impact melt pools in chondritic regoliths the eagle station trio pallasites and several ungrouped meteorites bencubbin weatherford enon acapulco and allan hills a77081 may have formed from impact melted chondritic material it is also possible that the parent magmas of ureilites were derived from impact melted metal rich carbonaceous chondrite material

cumberland falls chondritic inclusions ii trace element contents of forsterite chondrites and meteorites of similar redox state abstract mineralogic study of black inclusions in the cumberland falls enstatite achondrite revealed that they constitute a highly unequilibrated chondritic suite distinct from other chondrite groups this highly shocked suite the forsterite f chondrites exhibits mineralogic trends apparently produced during primary nebular condensation and accretion over a broad redox range we analyzed these samples and possibly related meteorites for ag as au bi cd co cs ga in rb sb se te tl u and zn trace elements known to yield important genetic information the results demonstrate the compositional coherence and distinctiveness of the f chondrite suite relative to other chondrites the antarctic aubrite alh a78113 may include more f chondrite material trace element contents do not vary with mineral compositions hence do not reflect redox variations during formation of f chondrite parental matter trace element mobilization during secondary heating episodes in the f chondrite parent or during its disruptive collision with the enstatite meteorite parent body is not detectable chemical trends in f chondrites apparently reflect primary nebular processes cosmochemical fractionation of lithophiles from siderophiles and chalcophiles occurred at moderately high temperatures certainly higher than those existing during formation of primitive carbonaceous enstatite and ordinary chondrites of petrologic type 3

ground movements over longwall workings in the kamptee coalfield india abstract subsidence investigations were conducted over three superimposed longwall panels in the kamptee coalfield of central india the extracted contiguous seams were lying below a water bearing unconfined aquifer filling of voids with sand hydraulically was practised to avoid a sudden inrush of water into the under ground workings through ground movement induced cracks the non effective width of extraction varied between 0 55 and 0 61 times the thickness of intact rockmass in the overburden the maximum subsidence slope compressive and tensile strains were 9 of extraction thickness 6 1 6 6 and 5 3 mm m 1 respectively the angle of draw was influenced by the presence of a fault and composition of superincumbent strata the ground movements lowered water table by 6 5 m in the unconfined aquifer due to the mining

separation and fracturing in overlying strata disturbed by longwall mining in a mineral deposit seam abstract mining induced fractures influence the stability of overburden and may provide pathways for transferring heat and mass in underground environment a novel approach was proposed to quantify the separation and fracture evolution in the undermined overburden consisting of 1 theoretical distribution models of the void ratios of fractures vrfs based on analytical evaluation of key strata subsidence and 2 numerical modeling using the universal distinct element code and a sequence of image post processing procedures for a longwall mining panel both theoretical calculations and numerical simulations indicated that vrf first increased rapidly then gradually decreased and finally stabilized to a minimum from the surrounding edges of disturbed strata to their centers and gradually decreased from deep to shallow strata the fractures exhibited a fracture rich arch distribution type along a vertical section numerous fractures occurred around the arch feet near the perimeters of mined out area and or arch crown near the center of disturbed strata the distributions of vrfs show the heights shapes and damage intensities of fractured zones and can also be used as porosity parameters to determine the permeabilities of mining disturbed overburdens therefore the vrf models can be used as a quantitative parameter to assess the extent of possible risk zones e g for water inflow into the mine or escape of hazardous fluids to the surface

evolution and classification of acapulcoites and lodranites from a chemical point of view we examined 15 bulk samples of the acapulcoite lodranite clan for their major minor and trace element concentrations using inaa techniques among the analyzed meteorites are 2 new acapulcoites dhofar dho 290 thiel mountains til 99002 as well as an additional acapulcoite that has been described previously only in very brief form graves nunataks gra 98028 the petrographic attributes of these 3 samples are addressed thoroughly we also include petrographic information on 2 acapulcoites from africa northwest africa nwa 725 and nwa 1058 in general our study strongly supports the widely accepted idea that acapulcoites and lodranites evolved through partial melting and melt migration of metal sulfide phases and plagioclase furthermore we concur with previous researchers that the original bimodal classification scheme for acapulcoites and lodranites proves to be too simple based on our data set we introduce an alternative extended scheme with respect to their elemental distribution patterns we distinguish 5 subtypes comprising primitive typical transitional and enriched acapulcoites on one hand and lodranites on the other the chemical distinction between the primitive typical and transitional acapulcoites is rather subtle and gradual it stands in contrast to the clear modifications observed for the signatures of the enriched acapulcoites and the lodranites the definition of subcategories basically reflects the concentrations of 2 key elements k and se we note however that the assignment of subgroups may not be exclusively inferred from elemental abundances but should also consider additional petrographic information

impact of karst water on coal mining in north china coalfields in north china encompass more than ten provinces they contain six to seven coal seams in the permo carboniferous strata the lower three seams account for 37 of the total reserves and are threatened with intrusion of karst water from the underlying ordovician limestone hundreds of water inrush incidences have occurred in which a large amount of water suddenly flows into tunnels or working faces under high potentiometric pressure over 50 mines have been flooded over the last 30 years large scale dewatering or depressurizing of the karst aquifer was considered essential to avoid water inrushes and keep the mines safely operational this practice however has caused sinkholes dry springs water supply shortage and groundwater contamination in the surrounding areas one alternative water control measure is to make full use of the rock layer between the coal seam and the karst aquifer as a protective barrier to prevent or constrain water flow from the underlying aquifer into the mines grouting is effective when the hydrogeological conditions are favorable to this technique proper design of the grouting program and experience of the contractor are also important for a successful application

evolution mechanism of water flowing zones and control technology for longwall mining in shallow coal seams beneath gully topography the height and evolution mechanism of fractured water flowing zones are of great importance for prevention of water inrush disasters and protection of immediate environments particularly in ecological vulnerable areas in this paper comparative approaches including empirical formula calculation physical simulation numerical simulation and protem transient electromagnetic analysis are employed to identify the development of the fracture zones caused by water flowing so as to ensure mining safety and protection of groundwater in shallow coal seams beneath gully topography an empirical formula was used to calculate the height of the water flowing fracture zone and an experimental study utilizing a model based on a similar material was adopted to analyze the movement and fracture development of the overlying strata results provide a reasonable basis from which a rational mining height may be determined the protem transient electromagnetic apparatus was employed to detect the water flowing structure conductivity of the overlying strata induced by mining beneath gully topography in the field the water flowing fracture of the overlying strata can be estimated according to comprehensive analysis of the apparent resistivity changes of the field gully surface crack development and aquifer water level accordingly the control technologies in the field were implemented and discussed regarding preventing gully water from rushing into underground mining spaces through water flowing fracture zones results indicate that safe and efficient mining of shallow seams beneath gully topography can be achieved by prevention of gully accidents and protecting the surface water resources of the ecological environment

the impact of key strata movement on ground pressure behaviour in the datong coalfield abstract in situ investigations are the most direct and authentic approach for determining the law of strata movement in this study in situ investigation was carried out to determine the law of fracture and movement of a key stratum four point surface extensometer fpse inside overlying strata and borehole camera observation were used in the overlying strata of a fully mechanized caving face of a super thick coal seam in the datong coalfield the time space correspondence between the fracture and movement of the key stratum and ground pressure in stopes was established in combination with observations of the ground pressure of the working face results show that the primary key stratum of the overlying strata is the main controlling stratum and its fracture and movement are the underlying cause of strong ground pressure behaviours such as rib spalling roof fall and support crushing the findings suggest that the primary key stratum can be weakened and the energy release can be decreased by hydraulic fracturing deep hole blasting and other measures thus relieving ground pressure behaviour the research method of establishing the time space correspondence between fracture and movement of the key stratum and ground pressure behaviours based on in situ investigation can provide guidance for mining engineering schemes such as exploring master control strata with strong ground pressure behaviour under similar conditions and determining a reasonable capacity for the support

the evolution of partially differentiated planetesimals evidence from iron meteorite groups iab and iiicd group iab irons probably come from a parent body that partially differentiated into a sulfur rich molten core and a primitive silicate outer layer in which only minor or localized melting occurred although the complexity of meteorites from this parent body or bodies irons with and without massive silicate inclusions stony meteorites like winona sulfide rich meteorites like mundrabilla etc implies a complicated history the partial differentiation model is consistent with most properties of these meteorites the behavior of five model parent bodies of different composition during heating to 1400 k the temperature recorded in many i ab silicates shows that meteorites like iab irons can form by this process sulfide rich parent bodies differentiate into a liquid s rich core and a primitive metal bearing mantle around 1230 k but in parent bodies lower in sulfide abundance this process may be delayed until minor melting of silicates occurs 1370 30 k in most cases any silicate melt that may have formed resolidified in situ the sulfide melt fractionally crystallized along the fe ni fes cotectic some melt was injected into silicates to form copiapo type breccias considerations of graphite metal silicate equilibrium and the retention of noble gases suggest that brecciated iabs formed at depth inside a moderately large a few tens to a hundred kilometers parent body the correlation of i xe ages with ni content is interpreted as the result of an excess 129xe component associated with the s rich melt which increases with melt evolution

geomorphology of coal seam fires abstract coal fires occur in underground natural coal seams in exposed surface seams and in coal storage or waste piles the fires ignite through spontaneous combustion or natural or anthropogenic causes they are reported from china india usa south africa australia and russia as well as many other countries coal fires lead to loss of a valuable resource coal the emission of greenhouse relevant and toxic gases and vegetation deterioration a dangerous aspect of the fires is the threat to local mines industries and settlements through the volume loss underground surface collapse in coal fire areas is common thus coal fires are significantly affecting the evolution of the landscape based on more than a decade of experience with in situ mapping of coal fire areas worldwide a general classification system for coal fires is presented furthermore coal seam fire geomorphology is explained in detail the major landforms associated with and induced by these fires are presented the landforms include manifestations resulting from bedrock surface fracturing such as fissures cracks funnels vents and sponges further manifestations resulting from surface bedrock subsidence include sinkholes trenches depressions partial surface subsidence large surface subsidence and slides additional geomorphologic coal fire manifestations include exposed ash layers pyrometamorphic rocks and fumarolic minerals the origin evolution and possible future development of these features are explained and examples from in situ surveys as well as from high resolution satellite data analyses are presented the geomorphology of coal fires has not been presented in a systematic manner knowledge of coal fire geomorphology enables the detection of underground coal fires based on distinct surface manifestations furthermore it allows judgments about the safety of coal fire affected terrain additionally geomorphologic features are indicators of the burning stage of fires finally coal fire geomorphology helps to explain landscape features whose occurrence would otherwise not be understood although coal fire induced thermal anomalies and gas release are also indications of coal fire activity as addressed by many investigators no assessment is complete without sound geomorphologic mapping of the fire induced geomorphologic features

ground subsidence observations and a modified influence function method for complete subsidence prediction abstract the results of surface subsidence investigations carried out in different coal fields in india are presented in this paper important differences are seen to exist between the subsidence norms given in the subsidence engineers handbook uk and those obtained in indian conditions differences also exist for extraction below unfractured or uncaved rock and below pre existing caved goaf s the subsidence is higher in the latter case and also in the slopes and strains consequently separate equations and guidelines have been given for these two conditions of mining since indian coal mining is mostly under shallow to moderate cover several cases of discontinuous subsidence have been observed a demarcation limit for discontinuous subsidence is given seeing that discontinuous subsidence causes severe surface damage since room and pillar mining is the principal underground method of extraction panels of irregular shapes often occur making complete subsidence prediction difficult the influence function method with a new function and additional functions for modelling subsidence asymmetry and the effect of extraction edges are given in this paper the method for extraction below goaf s is also examined four cases are given for the comparison of observed and predicted subsidence contours and two cases for comparison of the slopes and strains

dynamic loading induced by the instability of voussoir beam structure during mining below the slope abstract dynamic loading events in the longwall faces under slopes in the shendong coalfield china seriously limit the safety and efficiency of mining the slope characteristics such as direction height and angle determine the load type and the stability of the voussoir beam structure vbs formed by fractured blocks of the primary key stratum pks whether or not dynamic loading events will occur can be directly determined based on the presence or absence of a stable vbs in the pks based on this relationship six structural mechanical vbs models for different load distributions were established and then the effects of the slope direction height and angle on the stability of vbs was analysed changes of load type intensified the compression force between the hinged blocks when the compression force between blocks exceeded the strength of the rock vbs instability and dynamic loading events occurred the compression force in the vbs increased with increasing slope angle and height when the slope directions were similar becoming more pronounced for mining under the uphill sections of the slopes therefore a method of determining the critical slope parameter values indicating a risk of dynamic loading was proposed enabling such slopes to be recognised in advance measures such as slope top cutting or backfilling can then be applied to prevent potential dynamic loading accidents this study can provide guidelines for safe mining under geological conditions involving widespread slopes and gullies

relict chondrules in primitive achondrites remnants from their precursor parent bodies abstract we studied the petrography analyzed the chemical compositions constrained the closure temperatures via geothermometry and determined the oxidation states of relict chondrules in campo del cielo iab iron meteorite graves nunataks gra 98028 acapulcoite and netschaevo iie iron meteorite to constrain their formation conditions and investigate links to known meteorite groups despite having been thermally metamorphosed mineral phases within relict chondrules retain information about their precursor compositions the sizes and textures of relict chondrules and silicate and chromite compositions indicate that campo del cielo gra 98028 and netschaevo had distinct parent bodies that were similar to but different from known chondrite groups to determine the utility of relict chondrule sizes in thermally metamorphosed meteorites we determined the chondrule size distributions in the ll chondrites semarkona ll3 00 soko banja ll4 siena ll5 and saint severin ll6 and the h chondrites clovis no 1 h3 6 kesen h4 arbol solo h5 and estacado h6 as expected mean chondrule diameters increase with degree of thermal metamorphism we find that campo del cielo and gra 98028 were reduced during thermal metamorphism consistent with previous studies indicating that their precursors were initially more feo rich than their current compositions in contrast to previous studies we find no evidence for reduction of silicates in netschaevo normal zoning of olivine in netschaevo is consistent with crystallization and suggests its silicates are near their primary feo contents the presence of elongated chromite grains along olivine grain boundaries in netschaevo indicates formation during thermal metamorphism under oxidizing conditions due to the absence of reduction and the composition of chromite being distinct from that of metamorphosed h chondrites we conclude that netschaevo and by extension the iie iron meteorites are not from the h chondrite parent body

acapulco and lodran like achondrites petrology geochemistry chronology and origin we have performed petrologic and geochemical studies of five primitive achondrites alha81187 and alha81261 acapulco like eet 84302 transitional but acapulco like and lew 88280 and mac 88177 lodran like we have also performed 39ar 40ar chronology on alha81187 alha81261 and eet 84302 lew 88280 and mac 88177 contain more ferroan olivines orthopyroxenes clinopyroxenes and chromites than do the acapulco like achondrites plagioclase is present in only alha81187 alha81261 and eet 84302 its composition does not track that of the mafic silicates eet 84302 with the most calcic plagioclase contains olivine and pyroxene with an mg intermediate between alha81187 and alha81261 similarly spinels in eet 84302 have the same mg as those in alha81187 while pyroxenes in the former are more ferroan than in the latter acapulco like achondrites have sm sc ratios between 0 8 1 5 times h chondrites and na sc ratios are between 0 81 0 times h chondrites indicating that silicate partial melts have not been lost from these rocks siderophile and chalcophile elements are fractionated and show a trend of increasing ir ni ratios with decreasing se co ratios this variation is consistent with fractionation by partial melting in the fe ni s system eet 84302 is very depleted in se and troilite is a accessory phase indicating essentially total loss of the low temperature fe ni s melt in contrast the lodran like achondrites are depleted in the highly incompatible lithophile elements relative to more compatible elements sm sc ratios are 0 2 0 7 times and na sc ratios are 0 04 0 18 times h chondrites these data are consistent with a model for formation of the lodran like achondrites as partial melting residues however the low ir ni and high se co ratios in two lodran like achondrites suggest the metal troilite in these rocks is dominated by the low melting fraction in the fe ni s system this metal troilite was added to the silicates after partial melting depleted them in a basaltic fraction the ar ar release spectra yield good plateau ages of 4 507 0 024 ga alha81187 4 511 0 007 ga alha81261 and 4 519 0 017 ga eet 84302 in good agreement with previously determined ar ar ages for other acapulco like achondrites together the ar ar ages demonstrate that metamorphism on the acapulco lodran parent body occurred 4 51 0 02 ga ago roughly 50 ma after its formation the geochemical and petrologic evidence on the acapulco and lodran like achondrites suggest that heating on the parent body was localized and heterogeneous in space and time the parent body was probably not subjected to parent body wide magmatism in contrast to the case for 4 vesta and the hed meteorites

integrating satellite remote sensing techniques for detection and analysis of uncontrolled coal seam fires in north china abstract china is the biggest producer of coal in the world and mines about 1000 mt of raw coal per year approximately 70 of china s energy consumption is covered by coal at the same time it is estimated that about 20 mt of coal are being burnt in uncontrolled coal fires in china each year because these coal fires are spread out over the whole northern part of the country stretching from xinjiang province in the west to the pacific coast in the east it is extremely difficult to keep an overview of the development of known fires as well as of newly developing ones satellite remote sensing offers a powerful tool to observe and monitor such large regions however special methods and techniques have to be derived to accurately detect and monitor near surface coal seam fires in this paper an integrated satellite remote sensing approach is described allowing detection and monitoring of near surface coal seam fires by observing subtle land surface changes induced by the fires these changes include thermal surface anomalies changes in spectral surface characteristics as well as land subsidence caused by the fires the methods comprise the radar interferometric generation of digital elevation models dems for geometric referencing and orthorectification of satellite imagery dedicated analysis of thermal satellite data daytime and nighttime and multispectral analysis of land surface properties as well as the mapping of small scale land subsidence by means of differential radar interferometry it is shown how different satellite remote sensing methods can be synergistically combined to detect analyze and monitor near surface coal seam fires in arid or semiarid areas of north china first results show the successful application of the methods and furthermore a comparison with ground measurements is given while thermal and optical analysis of the fires can be considered robust methods the assessment of coal seam fires using differential radar interferometry still has to be further developed in order to serve as a reliable analysis and monitoring tool within this work a special focus is given to aspects of automation of the coal fire detection and analysis by means of satellite remote sensing in order to allow fire mapping in large areas with only minimal operator interaction

pot hole subsidence in son mahanadi master coal basin pot hole subsidence is an abrupt depression of local ground surface which occurs due to sudden collapse of the overburden into an underground void pot hole subsidence is a common form of subsidence in jamuna and kotma hasdeo and bisrampur areas of son mahanadi master coal basin data of 34 cases of pot hole subsidence were collected from the above areas and analysed from stand point of their causative factors prediction mechanism and suggested mitigative measures analysis of these cases revealed that shallow depth geological discontinuities weak and saturated overburden are the main causative factors for the pot holing phenomenon movement of eroded materials from saturated and weathered overburden with water along a fault plane into the underground bord and pillar development led to the formation of a pot hole risk of pot hole subsidence is high when the pot hole potential ratings of causative factors are between 80 and 100 suggested mitigative measures of pot hole subsidence in bord and pillar development as well as unapproachable depillared workings include maintaining a minimum of 15 m un weathered hard cover controlled width and height of drivages installation of suitable support system back filling grouting of underground voids etc

182hf 182w chronometry and the early evolution history in the acapulcoite lodranite parent body an acapulcoite northwest africa nwa 725 a transitional acapulcoite graves nunataks gra 95209 and a lodranite nwa 2235 have been studied with the short lived chronometer 182hf 182w system in order to better constrain the early evolution history in the acapulcoite lodranite parent body unlike the more evolved achondrites originating from differentiated asteroids e g eucrites and angritesbulk rock acapulcoites and lodranite are characterized by distinct 182w deficits relative to the terrestrial w as well as to the undifferentiated chondrites ew varies from 2 7 to 2 4 this suggests that live 182hf was present during the formation of acapulcoites and lodranites and their parent body probably had never experienced a global melting event due to the large uncertainties associated with the isochron for each sample the bulk isochron that regressed through the mineral separates from all 3 samples has provided the best estimate to date for the timing of metamorphism in the acapulcoite lodranite parent body 5 6 5 myr after the onset of the solar system it is thus inconclusive whether acapulcoites and lodranites have shared the same petrogenetic origin based on the hf w data of this study nevertheless the formation of acapulcoite lodranite clan appears to have post dated the metal silicate segregation in differentiated asteroids this can be explained by a slower accretion rate for the acapulcoite lodranite parent body or that it had never accreted to a critical mass that could allow the metal silicate segregation to occur naturally

the effects of the rotational speed of voussoir beam structures formed by key strata on the ground pressure of stopes abstract underground coal mining leads to fracture and movement in the overburden and the occurrence of weighting events in stopes there are certain key strata that play an important role in controlling overburden movements after the key stratum breaking the fractured blocks would form the voussoir beam structure the rotational speed of the voussoir beam structures directly affects the intensity of the ground pressures in a stope in this study a mechanical model was constructed to describe the rotational motions of the voussoir beam structures formed by the key strata based on elastomechanical theories the angular velocity equations for the rotational motions of the voussoir beam structures in the key strata were obtained moreover the manner in which loads and block lengths affect the angular velocity was investigated the rotational angular velocity of the fractured blocks was found to increase with greater overlying loads on the key strata and shorter block lengths the main roof has a major influence on strata behavior in stopes and increases in the angular velocity of its voussoir beam structures increase roof subsidence rates the yield of powered supports within each coal mining cycle and the intensity of weighting events in stopes if one or more of the voussoir beam structures formed by key strata above the main roof have greater rotational speeds than those of their underlying key strata additional loads are applied to the latter causing their rotational speeds to increase if this application of loads is transmitted to the main roof there is a strong possibility that highly intense weighting events will occur as a result of increases in the rotational speed of the main roof s voussoir beam structures the research result provided a rational explanation for the significant differences in the weighting events of the no 52304 working face in the daliuta coal mine which was covered by thick versus thin aeolian sands the results may be greatly significant in evaluating the intensity of weighting events predicting the scope in which the strata movement affects the weighting events in stopes and determining a reasonable powered support capacity

a petrologic and isotopic study of winonaites evidence for early partial melting brecciation and metamorphism we have conducted detailed petrologic chemical and isotopic studies of winonaites to ascertain the genesis of this group of meteorites winonaites have reduced mineral compositions and mineralogy and oxygen isotopic compositions distinct from primitive achondrite groups other than silicate inclusions in iab and iiicd irons however winonaites differ from iab and iiicd irons in that they lack the metallic matrices of the latter and consist mostly of silicates on the basis of these criteria winona mount morris wisconsin tierra blanca pontlyfni y 74025 y 75300 y 8005 and que 94535 are winonaites and y 75305 and y 75261 may be winonaites winonaites are fine to medium grained mostly equigranular rocks pontlyfni and mount morris wisconsin contain what appear to be relict chondrules several winonaites contain mm sized areas that differ substantially in grain size and or silicate mineralogy from the surrounding matrix fe ni fes veins are common in many winonaites mineral compositions are intermediate between e and h chondrites and reduced sulfides are observed in low feo winonaites bulk major element compositions are roughly chondritic although ree elements are fractionated the 39ar 40ar ages of three winonaites range from 4 40 ga mount morris wisconsin to 4 54 ga pontlyfni cosmic ray exposure ages are 20 80 ma trapped noble gases in these winonaites resemble those in enstatite chondrites we suggest that the winonaites formed from a chondritic precursor material unlike that of known chondrites in mineral and oxygen isotopic compositions and this material may have been heterogeneous in composition extensive heating caused metamorphism and partial melting of both fe ni fes and silicate material impact brecciation during cooling mixed lithologies with different thermal histories and subsequent metamorphism produced recrystallization grain growth and reduction of mafic silicates the 39ar 40ar ages indicate that cooling may have been more rapid than observed in iab irons although later resetting may have occurred

multiple mesozoic mineralization events in south china an introduction to the thematic issue mesozoic mineral deposits in south china include world class deposits of w sn and sb and those that provide the major sources of ta cu hg as tl pb zn au and ag for the entire country these deposits can be classified into polymetallic hydrothermal systems closely related to felsic intrusive rocks sn w mo granites cu porphyries polymetallic and fe skarns and polymetallic vein deposits and low temperature hydrothermal systems with no direct connection to igneous activities mvt deposits epithermal au and sb deposits recent studies have shown that they formed in the triassic indosinian jurassic cretaceous early yanshanian and cretaceous late yanshanian stages indosinian deposits include major mvt pb zn ag deposits and granite related w sn deposits early yanshanian deposits are low temperature sb au and high temperature w sn and cu porphyry types many late yanshanian deposits are low temperature au as sb hg and u deposits and also include high temperature w sn polymetallic deposits the formation of these deposits is linked with a specific tectonothermal evolution and igneous activities this special issue brings together some of the latest information in eight papers that deal with the origins and tectonic environments of mineral deposits formed in these stages we anticipate that this issue will stimulate more interests in these ore deposits in south china

re os isochron ages for arsenopyrite from carlin like gold deposits in the yunnan guizhou guangxi golden triangle southwestern china abstract the yunnan guizhou guangxi golden triangle is considered to be one of the regions hosting carlin like gold deposits in china gold deposits in this region can be grouped into lode type that are controlled by faults and layer like type controlled by stratigraphy arsenopyrite is one of the major gold bearing minerals in these deposits rhenium os isotopic dating of arsenopyrite from the lode type lannigou and jinya and the layer like type shuiyindong gold deposits yields isochron ages of 204 19 ma 206 22 ma and 235 33 ma respectively the data suggest that the carlin like gold deposits formed in late triassic to early jurassic which is clearly earlier than the ca 100 80 ma acid to ultra basic magmatism in this part of southwestern china the ages are consistent with ore formation during a period of post collisional lateral transpression which is similar to that of the carlin like gold deposits in western qinling of china but quite different from carlin type gold deposits in nevada u s a

in situ sims u pb dating of hydrothermal rutile reliable age for the zhesang carlin type gold deposit in the golden triangle region sw china the contiguous region between guangxi guizhou and yunnan commonly referred to as the golden triangle region in sw china hosts many carlin type gold deposits previously the ages of the gold mineralization in this region have not been well constrained due to the lack of suitable minerals for radiometric dating this paper reports the first sims u pb age of hydrothermal rutile crystals for the zhesang carlin type gold deposit in the region the hydrothermal u bearing rutile associated with gold bearing sulfides in the deposit yields an u pb age of 213 6 5 4 ma which is within the range of the previously reported arsenopyrite re os isochron ages 204 19 to 235 33 ma for three other carlin type gold deposits in the region our new and more precise rutile u pb age confirms that the gold mineralization was contemporaneous with the triassic w sn mineralization and associated granitic magmatism in the surrounding regions based on the temporal correlation we postulate that coeval granitic plutons may be present at greater depths in the golden triangle region and that the formation of the carlin type gold deposits is probably linked to the coeval granitic magmatism in the region this study clearly demonstrates that in situ rutile u pb dating is a robust tool for the geochronogical study of hydrothermal deposits that contain hydrothermal rutile

type curve analysis of water level changes induced by a longwall mine subsidence due to longwall mining creates long term environmental effects such as alteration of surface drainage patterns changes in aquifer characteristics and water level drops in wells near the mine panel evaluating the impact of longwall mining on groundwater resources requires a knowledge of aquifer properties both in front of and behind the mining face in this study we develop a method based on the one dimensional flow equation and utilize type curves to estimate an aquifer hydraulic diffusivity value from water level versus time measurements at a single well we tested the method by calculating the hydraulic diffusivity value of the trivoli sandstone aquifer over a longwall coal mine in the illinois basin and our results are reasonably close to reported values the presented method significantly reduces the computational effort involved in 1 predicting mine induced water level drops and 2 determining the hydraulic conductivity and storage coefficient value representative of a larger aquifer volume as compared to conventional aquifer test methods

temporal monitoring of coal fires in jharia coalfield india jharia coalfield jcf in india has one of the densest congregations of surface subsurface coal fires in the world evaluation of spatial dynamics and trend of coal fires propagation through aster thermal data has indicated that the magnitude of coal fires in jcf has been fluctuated with time from 2000 to 2009 the area located around western eastern and southeastern parts of the jcf covering shatabdi opencast barora sijua opencast godhar colliery kusunda bokapahari kujama and lodna is under intense coal fire from 2000 to 2004 spatial extent of coal fire has shown a minor decrease of 6 74 and then shows a substantial increase of 11 93 between 2004 and 2009 systematic analysis of the results has revealed that the movement of coal fire in jcf is structurally controlled propagation of the coal fires has been observed in kustor bastacolla and lodna collieries and fire appears to be spreading along the strike of coal seams toward jharia township