quantification of rock mass damage in underground excavations from microseismic event monitoring abstract rock mass damage assessment is required for many applications in rock engineering practice including support design contamination transport control stope design amongst others while various methods such as displacement measurement seismic refraction and direct observation using borehole camera have been used relatively few efforts have been made to use microseismic monitoring to quantify the rock mass damage from laboratory tests it is well known that microseismic events are indicators of fracturing or rock damage as the rock mass is brought to failure at high stress by capturing the microseismic events underground excavation induced rock mass degradation or damage can be located but can the amount of damage in terms of changes to strength or deformation properties be measured in the present study a method of characterizing rock mass damage near excavations based on microseismic event monitoring is developed and a damage driven numerical model is presented that takes the microseismic data as input to determine the damage state described by fracture density the approach is built on the discovery that a realistic crack size corresponding to a seismic event can be established by applying a tensile cracking model instead of the traditional shear model commonly used in earthquake analysis the rock mass is softened by the introduction of cracks and this is simulated by a micro mechanics based constitutive model the material property input for the model are young s modulus poisson s ratio of the intact rock and information obtained from the monitoring of microseismic events such as the location and the source size of each event calculated from source parameters using data from the atomic energy of canada limited mine by experiment this model has been verified by investigating the linkage between microseismicity rock mass damage and ground deformation it is found that when damage related softening based on microseismic data is considered predicted rock mass displacements are in good agreement with extensometer measurements

the behavior of thallium during alteration of the k alkaline rocks from the roccamonfina volcano campania southern italy tl behavior in the alteration of leucite and related k alkaline rocks from the quaternary roccamonfina volcano has been outlined the dominant weathering product is analcite that shows a moderate loss of tl relative to the coexisting leucite r 0 74 0 21 weathering of leucite to halloysite is subordinate and characterized by a very strong depletion in tl r 0 14 0 15 the geochemical coherence between tl and k observed in the roccamonfina igneous rocks breaks down when leucite weathers to analcite as unlike tl k is almost totally lost in contrast in the alteration of leucite to halloysite both elements still behave coherently being almost totally mobilized to groundwater thermodynamic calculations show that tl in the roccamonfina groundwater occurs mostly as tl oh 3 aq thus as tl occurs in the igneous rocks as tl i it is apparent that it oxidizes to tl iii after introduction to the hydrosphere in spite of the significant amount of tl made available by weathering of tl rich country rocks groundwaters from the study area are not tl enriched their contents matching the average for natural waters on the other hand at roccamonfina widespread sedimentary fe rich mn bearing occurrences are richer in tl than any other rock these findings lead one to infer that tl mobility as well as its concentration level in groundwater are strongly attenuated due to the scavenging properties of such fe and mn bearing sediments

interferometric seismic imaging around the active lalor mine in the flin flon greenstone belt canada abstract seismic interferometry which recovers the impulse response of the earth by cross correlation of ambient noise recorded at sets of two receivers has found several applications including the generation of virtual shot gathers for use in seismic reflection processing to evaluate the effectiveness of this passive recording technique in mineral exploration in a hard rock environment 336 receivers recorded 300 h of ambient noise over the volcanogenic massive sulphide deposit of the recently discovered lalor mine in the canadian flin flon greenstone belt a novel time domain beamforming algorithm was developed to search for individual source locations demonstrating that the vast majority of noise originated from the mine and ventilation shafts of the lalor mine the results of the beamforming were utilized in conjunction with frequency wavenumber filtering to remove undesirable mostly monochromatic surface wave noise originating from nearby sources virtual shot gathers were generated along three receiver lines each of which was processed as a separate 2 d reflection line two of the resulting unmigrated reflection profiles are compared against coincident dipmoveout stacked data from a larger coincident 3 d dynamite seismic survey that was also acquired over the lalor mine in 2013 using knowledge of the local geology derived from numerous boreholes coherent events recovered in the passive reflection profiles are inferred to be either spurious arrivals or real reflections some of which can be interpreted in terms of geological contacts indicating the future potential of passive recording surveys in hard rock settings

landstreamer seismics and physical property measurements in the siilinjarvi open pit apatite phosphate mine central finland abstractwe tested the applicability of a newly developed broadband 0 800 hz digital based seismic landstreamer for open pit mine planning in the apatite bearing siilinjarvi mine in central finland four seismic profiles in total approximately 2 5 km long 2 4 m source and landstreamer receiver spacing two inside the pit and two on its margins were acquired in combination with wireless recorders connected to 10 hz geophones and fixed at every 10 m spacing along the seismic profiles while the streamer data were being acquired downhole logging and laboratory physical property measurements on core and rock samples were carried out to not only support the seismic interpretations but also to provide information about the possible geophysical signature of these unique types of deposits in spite of a highly noisy mining environment seismic data of high quality were acquired however reflection processing and interpretations were challenged by the geologic complexities of several generations of basic and

abundance and behavior of thallium in the k alkaline rocks from the roccamonfina volcano campania southern italy abstract the tl content in whole rocks matrix and mineral separates leucite sanidine biotite phlogopite from 58 igneous rocks of the k alkaline suites of the roccamonfina volcano has been measured by polarographic technique the tl content increases with magmatic differentiation indicating that tl is a magmaphile element in these magma suites the tl content does not distinguish mafic rocks of the high k series relative to those of the k series indicating that in this respect tl is not similar to k and other lil elements among minerals leucite x 6417 ppb is enriched in tl relative to sanidine x 2345 ppb and biotite x 2417 ppb average d leuc matrix tl d san matrix tl and d biot matrix tl are 3 67 0 65 and 1 86 respectively the roccamonfina primitive rocks display tl contents x 582 ppb similar to those of basalts of continental settings and close to the value of the average crust x 491 ppb both crustal contamination and mixing between a normal mantle and a lil enriched mantle material can account for such high tl contents in the roccamonfina primitive rocks

2d reflection seismic investigations at the kevitsa ni cu pge deposit northern finland in 2007 a 2d reflection seismic survey was conducted at the kevitsa ni cu pge platinum group elements deposit in northern finland the aims of the survey were to delineate the overall extent of

building a 3d model of lithological contacts and near mine structures in the kevitsa mining and exploration site northern finland constraints from 2d and 3d reflection seismic data the kevitsa mafic ultramafic intrusion in northern finland hosts a large disseminated nickel copper sulphide ore body the kevitsa intrusion is an active mining and exploration site for which we

prediction of sonic velocities from other borehole data an example from the kevitsa mine site northern finland p wave and s wave velocities are vital parameters for the processing of seismic data and may be useful for geotechnical studies used in mine planning if such data were collected more often seismic velocity data from boreholes increase the robustness and accuracy of the images obtained by relatively costly seismic surface reflection surveys however sonic logs are rarely acquired in boreholes in and near base metal and precious metal mineral deposits until a seismic survey is planned and only a few new holes are typically logged because the many hundreds of holes previously drilled are no longer accessible if there are any pre existing petrophysical log data then the data are likely to consist of density magnetic susceptibility resistivity and natural gamma logs thus it would be of great benefit to be able to predict the velocities from other data that is more readily available in this work we utilize fuzzy c means clustering to build a fuzzy relationship between sonic velocities and other petrophysical borehole data to predict p wave and s wave velocity if boreholes with sonic data intersect most of the important geological units in the area of interest then the cluster model developed may be applied to other boreholes that do not have sonic data but do have other petrophysical data to be used for predicting the sonic logs these predicted sonic logs may then be used to create a three dimensional volume of velocity with greater detail than would otherwise be created by the interpolation of measured sonic data from sparsely located holes our methodology was tested on a dataset from the kevitsa ni cu pge deposit in northern finland the dataset includes five boreholes with wireline logs of pwave velocity s wave velocity density natural gamma magnetic susceptibility and resistivity that were used for cluster analysis the best combination of input data for the training section was chosen by trial and error but differences in themisfit between the various training datasets were not particularly significant our results show that the fuzzy c means method can predict sonic velocities from other borehole data very well and the fuzzy c meansmethod works better than using multiple linear regression fitting the predicted p wave velocity data are of sufficient quality to robustly add low frequency information for seismic impedance inversion and should provide better velocity models for accurate depth conversion of seismic reflection data

the coal mine roof rating cmrr a decade of experience abstract the coal mine roof rating cmrr was developed 10 years ago to fill the gap between geologic characterization and engineering design it combines many years of geologic studies in underground coal mines with worldwide experience with rock mass classification systems like other classification systems the cmrr begins with the premise that the structural competence of mine roof rock is determined primarily by the discontinuities that weaken the rock fabric however the cmrr is specifically designed for bedded coal measure rock since its introduction the cmrr has been incorporated into many aspects of mine planning including longwall pillar design roof support selection feasibility studies extended cut evaluation and others it has also become truly international with involvement in mine designs and funded research projects in south africa canada and australia this paper discusses the sources used in the development of the cmrr describes the cmrr data collection and calculation procedures and briefly presents a number of practical mining applications in which the cmrr has played a prominent role

geomechanical behaviour of laminated weak coal mine roof strata and the implications for a ground reinforcement strategy this paper describes a component of the results from an arc spirt funded collaborative research project between unsw powercoal pty ltd and springvale coal pty ltd the research project was aimed at identifying strategies for appropriate ground control in particularly weak and soft roof strata in underground coal mining a field investigation was undertaken at angus place colliery in the western coalfield of new south wales the investigation incorporated a range of geotechnical instrumentation and was conducted over a period of time from the development face until the site was lost into the goaf of a retreating longwall panel this paper describes the outcomes from the field investigation together with a selection of supporting laboratory studies the paper also presents a number of alternative presentation modes for extensometry data the results clearly demonstrate the time and face proximity related influences on roof integrity and particularly demonstrated the distribution of deformation bed separation and strata failure into the roof and across the full span of the roadway together with reflection of this behaviour within the fully encapsulated roof bolt reinforcement system installed

distribution and behavior of lithium in the k alkaline rocks from the roccamonfina volcano campania southern italy abstract the li content in whole rocks matrix and mineral separates biotite sanidine leucite phlogopite from 58 igneous rocks of the k alkaline suites of the roccamonfina volcano has been measured by atomic absorption among the minerals sanidine contains as much li as biotite x 41 8 ppm and x 40 2 ppm respectively while phlogopite and leucite have a much smaller amount x 6 0 ppm and x 2 6 ppm respectively average li distribution coefficients between minerals and groundmass are d biot matrix li 0 50 d san matrix li 0 84 and d leuc matrix li 0 06 respectively the li content increases with magmatic differentiation in the rocks of the k series showing an enrichment factor of 3 6 in the salic relative to the mafic rocks in the high k series the li content increases from primitive to intermediate rocks but shows a levelling off in the more salic rocks li acts incompatibly except in the most salic rocks whose li content was probably mainly controlled by diffusion processes through the magmas the li content in the roccamonfina primitive rocks x 20 ppm does not discriminate between the k and high k series and is higher than that of the average basalt x 10 ppm however it is similar to that of basalts from continental settings this relatively high li content in the roccamonfina primitive rocks can be accounted for by either crustal contamination or the existence of an enriched mantle region beneath the volcano but in both hypotheses there is a suggestion of some involvement of the lower crust in the generation of the roccamonfina parental magmas

seismic imaging of massive sulfide deposits part i rock properties laboratory measurements of the density rho and compressional wave velocity v p of massive sulfides and host rocks at elevated pressures show that ores occupy a v p rho field which is distinct from that of common silicate rocks and governed by simple mixing rules between the properties of host rocks and pure sulfide minerals the velocities of the most common sulfides are extremely variable ranging from 3 7 km s for galena through 4 7 km s for pyrrhotite 5 6 km s for sphalerite and chalcopyrite to 8 0 km s for pyrite but their densities are always high 7 6 4 6 4 1 4 2 and 5 0 g cc respectively causing ores of even intermediate grade to have high acoustic impedances this suggests that large massive sulfide bodies should make strong to spectacular seismic reflectors depending on their grade mineralogy size and setting in principle it should thus be possible to use high resolution seismic reflection techniques for base metal exploration and delineation

data mining of petrophysical and lithogeochemical borehole data to elucidate the origin of seismic reflectivity within the kevitsa ni cu pge bearing intrusion northern finland the kevitsa mafic ultramafic intrusion located within the central lapland greenstone belt in northern finland hosts a large disseminated ni cu pge sulphide deposit a three dimensional seismic r

new method for determining the elastic parameters of rock mass layers in the region of underground mining influence abstract the primary objective of the following paper is to determine the value of strata elastic parameters in a selected polish mining area using a new method based on finite element analysis gsi geotechnical classification and back analysis the individual rock layer strain parameters were estimated by means of comparing the measured subsidence trough with the result of numerical analysis carried out for the same geological and mining conditions as a result of such an analysis the values of the elastic modulus of the anisotropic model of strata were obtained in the region of underground mining influence

distribution and behavior of lead in the k alkaline rocks from the roccamonfina volcano southern italy abstract the pb content in whole rocks matrix and mineral separates sanidine leucite biotite and phlogopite from 53 igneous rocks of the k alkaline suites of the roccamonfina volcano has been measured by means of the polarographic technique an increase of the pb content is observed with magmatic differentiation indicating that pb behaves as a magmatophile element in these magma suites moreover pb is enriched by a factor of 1 7 in the primitive rocks of the high k series compared with the primitive rocks of the k series and in this respect pb is similar to k and other lil elements sanidine x 44 7 16 9 ppm is 10 times enriched in pb relative to both leucite x 3 6 1 9 ppm and biotite x 5 3 3 1 ppm and this is in good agreement with the different coordination numbers of k in the structures of these minerals average d san matrix pb d leuc matrix pb d biot matrix pb are 0 48 0 05 0 14 respectively primitive rocks of both the k series and the leucite basalt series have a much higher pb content alkali olivine basalts and olivine trachybasalts x 16 3 ppm leucite basalts x 9 7 ppm than the average alkali basalt x 4 3 ppm and close to the average crust x 12 ppm primitive rocks of the high k series display a pb content as high x 28 4 ppm as those of several granitic rocks plots of pb vs other incompatible elements ratio vs ratio suggest that the hks and ks parental magmas could be derived by mixing between a normal mantle material and a lil enriched mantle material

seismic reflection profiling of the pyhasalmi vhms deposit a complementary approach to the deep base metal exploration in finland abstractin the pyhasalmi case study the seismic data is used in direct targeting of shallowly dipping mineralized zones in a massive sulfide ore system that was deformed in complex fold interference structures under high grade metamorphic conditions the pyhasalmi volcanic hosted massive sulfide vhms deposit 50 mt is located in a proterozoic volcanic belt in central finland acoustic impedance of pyhasalmi ore 32 106 kg m2 s is distinct from the host rocks 16 19 106 kg m2s enabling its detection with seismic reflection methods drill hole logging further indicates that the seismic imaging of a contact zone between mafic and felsic volcanic rocks possibly hosting additional mineralizations is plausible six seismic profiles showed discontinuous reflectors and complicated reflectivity patterns due to the complex geology the most prominent reflective package at 1 2 km depth was produced by shallowly dipping contacts between interlayered felsic and mafic volcanic rocks the topmost of these b

inducing mode analysis of rock burst in fault affected zone with a hard thick stratum occurrence study of movement characteristics of a hard thick stratum hts affected by a fault in a coalmine is significant to predict the dynamic hazards i e rock bursts and shock bumps because of the particular structural and mechanical properties of the hts and the fault hence using udec numerical simulation the movement characteristic of hts and fault slipping law with different mining directions towards the fault were studied then two different inducing modes and corresponding mechanisms of rock burst were obtained the results show that the structure of overlying strata on two fault walls is different because of fault cutting and fault dip it results in the hts of two fault walls presenting different movement stage characteristics from analysis of fault plane stress and fault slipping we obtain that footwall mining has higher risk of rock burst than hanging wall mining finally summarizing two different inducing modes of rock burst affected by the hts and the fault one that mainly resulted from the strain energy release caused by the hts obvious bending and failure i e hanging wall mining and one that notably affected by fault slipping and hts failure subsidence i e footwall mining a field case regarding microseismic monitoring is used to verify the numerical simulation results study results can serve as a reference for predicting of rock bursts and their classification into hazardous areas under similar conditions

origin of ultra nickeliferous olivine in the kevitsa ni cu pge mineralized intrusion northern finland the 2 058 4 ma mafic ultramafic kevitsa intrusion is located in the central lapland greenstone belt northern finland it is hosted by a paleoproterozoic volcano sedimentary sequence that contains komatiitic volcanic rocks and sulfide and graphite rich black schists economic ni cu pge sulfide mineralization occurs in the middle part of the ultramafic lower unit of the intrusion two main types of ore are distinguished normal and ni pge ores the normal ore is characterized by 2 to 6 vol disseminated sulfides and average ni and cu grades of 0 3 and 0 42 wt respectively ni cu 1 the ni pge ore has broadly similar sulfide contents but a higher ni grade and lower cu grade as a result the ni cu ratio reaches 15 much higher than in the normal ore the ni pge ores occur as irregular discontinuous lense like bodies in the ultramafic rocks notably the olivines in the ni pge ore contain extremely high ni contents of up to 14 000 ppm which is significantly higher than the ni content of olivine in other mafic ultramafic igneous rocks globally up to 5 000 ppm and in harmony with the associated ni rich sulfide assemblage containing pentlandite millerite and pyrite microprobe mapping of olivine from the ni pge ore suggests relatively low and homogeneous s contents and homogeneous distribution of ni mg fe which is inconsistent with the presence of sulfide inclusions in the olivine grains or diffusion of ni from interstitial sulfides into the olivine grains we therefore conclude that ni substitutes for mg in the olivine lattice the clinopyroxenes from the ni pge ore also have unusually high ni concentrations reaching 1 500 ppm and show a positive correlation with the nickel content of the associated olivine the nicpx niolivine is 0 1 to 0 2 corresponding to high t partitioning of ni between clinopyroxene and olivine k d of 20 can account for the partitioning of nickel between olivine and the sulfide phase consistent with magmatic equilibration these data suggest that the olivine clinopyroxene and sulfides all crystallized from a basaltic magma with an unexceptionally high ni content ranging from 300 to 1 100 ppm the ni pge ores are spatially associated with ultramafic xenoliths olivine in these ultramafic xenoliths have relatively high fo contents up to 90 mol and high ni contents up to 5 200 ppm suggesting that the xenoliths formed from a komatiitic parental magma it is proposed that assimilation by the kevitsa magma of massive or semi massive sulfides associated with komatiitic rocks elevated the ni content of the magma and resulted in the formation of ni pge ores and related extremely ni rich olivines

seismic methods for deep mineral exploration mature technologies adapted to new targets nonseismic methods such as electromagnetic induced polarization and potential field surveying techniques have been the geophysical backbone of mineral exploration for decades these methods exploit anomalous physical properties of ore deposits e g enhanced conductivity chargeability or magnetization to locate potential targets for drilling although well suited to many shallow 500 m exploration problems the underlying physical principles of these methods impose inescapable limitations on their sensitivity and resolving power at depth recent declines in base metal reserves caused by the depletion of known shallow deposits and declining rates of discovery for new deposits underscore the need for geophysical exploration methods that can locate economically viable deposits at depths of up to several km seismic methods offer one possible solution the need to develop efficient and robust seismic imaging techniques for mineral exploration has long been recognized in the 1980s two key case histories established the potential of seismics as a mapping tool in the hardrock environment green and mair 1983 presented seismic images of complex fracture systems at a radioactive waste disposal site in the canadian shield subsequently pretorius et al 1989 demonstrated the usefulness of an integrated seismic and petrophysical approach to image key geologic structures for mineral exploration in witwatersrand basin south africa these initial studies served as catalysts for a number of largely independent research efforts over the following decade in north america southern africa scandinavia and australia aimed at developing useful and cost effective seismic technology for deep mineral exploration and mine planning a number of fundamental aspects of seismic exploration for minerals including the acoustic properties of ores and the scattering characteristics of orebodies were poorly known until recently moreover significant advances have been made in seismic imaging technology for mineral exploration from downhole seismic techniques to large scale 3d surveys over known deposits this article reviews some advances in applying seismic

correlation between petrographic characteristics and failure duration in clastic rocks being the inherent attributes of rock the petrographic characteristics such as mineral composition and microstructure are the constructive parameters which influence its bursting potential in the laboratory rock specimens with different petrographic characteristics are tested to study their rock strength and failure duration and correspondingly composition and microstructure of each rock specimen are analyzed in thin sections to determine the mineral composition content grain size cement and contact modes between grains the results show that the petrographic characteristics of clastic rock have an intrinsic influence on its strength and failure duration with the increase of the rock detritus content or quartz the uniaxial compressive strength increases according to a logarithmic expression and the failure duration decreases according to a negative logarithmic expression with increasing average size of detritus grains in rock the stiffness and brittleness of rock strengthens the uniaxial compressive strength of rock has a logarithmic variation with its average size of detritus grains and the failure duration decreases with its increasing average size of detritus grains according to a negative logarithmic expression

a review of reflection seismic investigations in three major metallogenic regions the kevitsa ni cu pge district finland witwatersrand goldfields south africa and the bathurst mining camp canada abstract effective exploration for mineral deposits depends on a sound understanding of the processes and geological structures that contributed to their formation the reflection seismic method has proven to be a powerful tool that provides a high resolution image of the subsurface and information about structural and lithological relationships that control mineral deposits the method has also become an attractive geophysical tool for deep exploration and mine planning in this paper we review the use of reflection seismic methods to obtain a better understanding of the architecture and ore forming processes of three diverse mineral regions the kevitsa ni cu pge district in finland the goldfields of the witwatersrand basin south africa and the bathurst mining camp canada seismic data both 2d and 3d from the kevitsa deposit clearly image the 3d geometry of the ore bearing intrusion and provide information about its relationship to the host rock units and nearby intrusions within a larger tectonic framework 3d seismic data from the witwatersrand basin not only provide clear images of major structures including a distinct reflection that acts as a marker horizon for the gold bearing reef but also provide information that may be useful in resolving a long standing controversy regarding the origin of the gold in the basin for example it might be possible to show that dykes formed impermeable barriers thereby falsifying the epigenetic hydrothermal models 2d and 3d seismic data from the brunswick no 6 area in the bathurst mining camp suggest that the brunswick horizon which contains the bulk of the massive sulfide and associated iron deposits occurs within a reflective package that extends down to at least 6 7 km depth

cross profile seismic data acquisition imaging and modeling of iron oxide deposits a case study from blotberget south central sweden cross profile seismic data acquisition imaging and modeling of iron oxide deposits a case study from blotberget south central sweden

heterogeneity and seismic scattering in exploration environments abstract seismic scattering and the corresponding reduction in signal to noise ratio is a severe limitation to seismic exploration in crystalline environments in this paper we summarize recent elastic numerical modeling of scattering regimes and discuss the implications for seismic exploration in shallow hardrock environments the resulting synthetic seismograms range from relatively transparent to highly reflective depending on the ratio of seismic wavelength to heterogeneity scale length we note that the archean canadian shield is characterized by large scale lengths typical for crystalline environments which translates to moderately reflective seismic sections exhibiting scattering features that are coherent over large distances in contrast the highly fractured footwall of the sudbury impact structure in the canadian shield translates to a medium with small to moderate scale lengths resulting in seismic sections that can in places be highly reflective or relatively transparent from the perspective of mineral exploration in sudbury we find that the possible detection of massive sulfide targets is dependent not only on the shape and size of the deposit but on the scattering nature of the background as well with information about the petrophysical properties and the distribution of heterogeneity within an exploration area acquisition parameters such as source frequencies and minimum receiver spacing can be adjusted in order to survey within the scattering regime that will produce the least amount of noise

in situ strontium and sulfur isotope investigation of the ni cu pge sulfide ore bearing kevitsa intrusion northern finland the 2 06 ga kevitsa mafic ultramafic intrusion in northern finland hosts a large disseminated ni cu pge deposit the deposit occurs in the ultramafic olivine pyroxene cumulates and shows a range in ni tenors varying from 4 7 wt regular ore to 10 wt ni pge ore there are also a metal poor sulfide mineralization false ore and contact mineralization that are uneconomic ni tenor 0 7045 in comparison to the estimated depleted mantle sr isotope ratio of 0 702 at 2 06 ga the sulfur 34s values are generally higher than 2 which together with the sr isotope data imply involvement of crustal material in the genesis of the kevitsa intrusion and its ores the 87sr 86sr i values obtained from the ore bearing domain of the intrusion show stratigraphic variation and exceed 0 7050 with the maximum value reaching up to 0 7109 in contrast in rocks around the ore domain the initial sr isotope compositions remain more or less constant 0 7047 0 7060 throughout the intrusive stratigraphy the isotope data suggest that the ore bearing domain of the intrusion represents a dynamic site with multiple injections of variably contaminated magma whereas the surrounding part of the intrusion experienced a less vigorous emplacement history no correlation is observed between the strontium and sulfur isotope compositions this is explained by bulk assimilation of the silicate magma in a deeper staging magma chamber and variable assimilation of sulfur during magma transport into the kevitsa magma chamber the low level of metals in false ore and the ni depleted nature of its olivine suggest that some sulfides may have precipitated and deposited in the feeder conduit during the initial stage of magma emplacement cannibalization of early formed sulfides by later magma injections may have been important in the formation of the economic ore deposit

numerical methods in rock mechanics the purpose of this civilzone review paper is to present the techniques advances problems and likely future development directions in numerical modelling for rock mechanics and rock engineering

why 3d seismic data are an asset for exploration and mine planning velocity tomography of weakness zones in the kevitsa ni cu pge mine northern finland kevitsa is a disseminated ni cu pge platinum group elements ore body in northern finland hosted by an extremely high velocity 6 5 8 5 km s ultramafic intrusion it is currently being mined at

li pb and tl abundances in the k alkaline rocks from the middle latina valley volcanoes southern latium italy and their petrological significance li pb and tl contents of 15 primitive lava samples from the middle latina valley volcanoes southern latium italy are higher in the high k than in the k series rocks the enrichment factors roughly following the increase of the ionic size of the elements

geomechanical simulation of low order fracture of tight sandstone abstract the core factors in the study of fractures within tight sandstone reservoirs are tectonics geomechanics and fluid mobility which are not independent but are coupled to each other in this paper taking the upper paleozoic gas reservoir within the low amplitude tectonic zone in the sulige gas field of the ordos basin as an example the developmental characteristics and geomechanical model of fractures and their relationships with the productivity of tight gas sandstone reservoirs were systematically studied the results show that this low amplitude structural zone develops mainly low order ruptures the paleotectonic stress field of the target layer in the yanshanian period was restored using a 3d finite element method the horizontal principal stresses exhibited stress diffusion and were affected by local low amplitude structures there was a positive correlation between h and h and h h was distributed primarily between 1 35 and 1 95 with an average of 1 62 the strain energy density u was calculated to quantitatively characterize the microfracture distribution of the target layer based on the principle of energy conservation there are certain positive correlations between u and the horizontal principal stresses the geostresses of high u regions underwent a certain degree of stress torsion which manifested as a stress deflection reaching up to 30 during stress propagation finally we proposed the concept of u value geomechanical sweet spots in a tight gas sandstone based on this criterion commercial gas wells can be effectively identified

seismic methods in mineral exploration and mine planning introduction across the globe the mineral industry is seeking technology to improve exploration efficiency at depth and to help design safer and more productive mines seismic methods are increasingly used by this industry for a wide range of commodities including base metals uranium diamonds and precious metals seismic methods provide high resolution images of geologic structures hosting mineral deposits and in a few cases can be used for direct targeting of mineral deposits applications are not limited to only surface seismic surveys but also include borehole seismic methods such as vsp and crosshole imaging to date tens of 2d and 3d surface seismic surveys have been acquired in canada europe australia and south africa see malehmir et al 2012 to help in targeting mineral deposits at depth or for designing deep mines the steadily increasing usage of reflection seismic methods demonstrates that they are finally becoming recognized and established within the mining sector this brings new opportunities for geophysicists but also new challenges some of these challenges and opportunities are presented and discussed in the special section this special issue contains a wide range of topics from petrophysical studies to data acquisition processing and imaging as well as 2d and 3d seismic modeling of mineral deposits and their host rock structures papers from both industry and academia are presented which illustrate the importance of seismic methods not only in the hydrocarbon industry but also in the mineral industry malehmir et al review important contributions that have been made in developing seismic techniques for the mining industry with focus on four main regions australia europe canada and south

improved target illumination at ludvika mines of sweden through seismic interferometric surface wave suppression in mineral exploration new methods to improve the delineation of ore deposits at depth are in demand for this purpose increasing the signal to noise ratio through suitable data processing is an

effects of hydrous alteration on the distribution of base metals and platinum group elements within the kevitsa magmatic nickel sulphide deposit abstract platinum and nickel are commonly assumed to be immobile in most conditions especially during low temperature hydrothermal alteration however only a small number of studies have rigorously tested this assumption the ni cu pge sulphide ore body hosted by the kevitsa intrusion northern finland provides a natural laboratory to study the behaviour of base metals and platinum group elements pge during low temperature alteration this ca 2060 ma mafic ultramafic intrusion located in the central lapland greenstone belt hosts disseminated ni cu pge sulphide mineralisation in the middle part of the main ultramafic body the mineralisation which contains a range of ni cu and pge grades is affected by three main alterations serpentinisation amphibolitisation and epidotisation and is cross cut by various types of veins the effect of the circulation of hydrothermal fluids on the distribution of base metals and pge was studied at two different scales interrogation of an extensive deposit wide assay database provided information on the deposit scale kilometre scale effect of these different alteration styles and a detailed study involving laboratory x ray fluorescence xrf portable xrf and micro xrf mapping of drill core samples containing cm scale cross cutting veins provided information on the small scale centimetre to decimetre scale remobilisation of base metals and pges results show that the hydration and carbonation of the kevitsa mineralised mafic ultramafic intrusion did not significantly affect the distribution of ni and pge at scales larger than a few mm and that cu and au are the only metals that are affected by small to large scale remobilisation from centimetre to kilometre scale

seismic imaging of massive sulfide deposits part ii reflection seismic profiling seismic reflection profiling the dominant geophysical method for hydrocarbon exploration has the potential to provide images of regional structure for mineral exploration in the crystalline crust and direct detection of large massive sulfide orebodies previous tests of traditional seismic methods in hard rock environments have had mixed success based on these earlier results we have tailored acquisition and processing strategies to conditions in the canadian shield we illustrate these methods using an example from the sudbury basin a rich mineral producing region because of structural complexity that complicates interpretation of the seismic images the seismic data are integrated with detailed three dimensional forward modeling based on physical properties studies mine geology and well logging through this integrated approach we show that massive sulfides can produce a characteristic seismic reflection response and that surface seismic reflection profiling may be used to detect and delineate deep large massive sulfide deposits accurately in a complex geologic setting characterized by moderate dips

influence of fracture induced weakening on coal mine gateroad stability abstract the ground stability of gateroads is a major concern in underground coal mines especially when the surrounding strata are weak and fractured this paper presents a novel numerical modelling technique for gateroad stability analysis based on a case study conducted at zhaogu no 2 mine china considering the occurrence of fracturing and its weakening effect on the stiffness of the rock mass a tension weakening model is implemented into flac3d whereby the stiffness of the rock mass is progressively decreased with the failure state a relationship between the intensity of fractures and the residual strength of the rockmass is built in the numerical model a parametric study of the tension weakening model is carried out and the results are compared to elastic perfectly plastic and strain softening models it is shown that the tension weakening model exhibits noticeable effects on ground deformation and rock support loading which are observed from field measurements thus the tension weakening model offers a more realistic simulation of the gateroad behavior than elastic plastic and strain softening models the proposed model can be utilized for other applications involving rock reinforcement of mine openings under similar geotechnical conditions

surface wave analysis for static corrections in mineral exploration a case study from central sweden in mineral exploration increased interest towards deeper mineralizations makes seismic methods attractive one of the critical steps in seismic processing workflows is the static correction which

a matlab toolbox and excel workbook for calculating the densities seismic wave speeds and major element composition of minerals and rocks at pressure and temperature to interpret seismic images rock seismic velocities need to be calculated at elevated pressure and temperature for arbitrary compositions this technical report describes an algorithm software and data to make such calculations from the physical properties of minerals it updates a previous compilation and excel spreadsheet and includes new matlab tools for the calculations the database of 60 mineral end members includes all parameters needed to estimate density and elastic moduli for many crustal and mantle rocks at conditions relevant to the upper few hundreds of kilometers of earth the behavior of and quartz is treated as a special case owing to its unusual poisson s ratio and thermal expansion that vary rapidly near the transition the matlab tools allow integration of these calculations into a variety of modeling and data analysis projects

seismic methods in mineral exploration and mine planning a general overview of past and present case histories and a look into the future abstractdue to high metal prices and increased difficulties in finding shallower deposits the exploration for and exploitation of mineral resources is expected to move to greater depths consequently seismic methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration these methods also can be used with varying degrees of success to directly target mineral deposits at depth we review important contributions that have been made in developing these techniques for the mining industry with focus on four main regions australia europe canada and south africa a wide range of case studies are covered including some that are published in the special issue accompanying this article from surface to borehole seismic methods as well as petrophysical data and seismic modeling of mineral deposits at present high resolution 2d surveys mostly are performed in mining areas but there is a general increasing trend in the use of 3

modeling mechanical layering effects on stability of underground openings in jointed sedimentary rocks abstract this paper examines the significance of mechanical layering for blocky rock mass deformation around underground openings excavated through sedimentary rocks the analysis is based on an integration of geologically based discrete fracture models geodfn which incorporate mechanical layering with the numerical discrete element method the discontinuous deformation analysis dda we begin with addressing limitations of classical solutions for mine roof stability in layered and jointed rock masses via the analysis of the free standing unsupported 2000 year old underground quarry known as zedekiah s cave below the old city of jerusalem israel we show that both the clamped beam model and the voussoir beam analogue fail to predict the observed roof stability only application of discrete element modeling which allows for interactions between multiple blocks in the rock mass can capture correctly the arching mechanism which takes place in the roof and which properly explains the long term stability of this underground opening we continue with examining the effect of joint trace geometries on blocky rock mass deformation using the hybrid geodfn dda approach we show that with increasing joint length and decreasing bridge length vertical deformations in the rock mass are enhanced we explain this by the greater number of distinct blocks in the rock mass due to the greater joint intersection probability in such geometries we find that rock bridge length is particularly important when considering the stability of the immediate roof with increasing rock bridge length the number of blocks in immediate roof decreases and consequently individual block width is increased increased block width in immediate roof layers enhances stable arching development thus improving their load carrying capacity and overall stability of the underground structure

evaluation of the 2d reflection seismic method toward the exploration of thrust controlled mineral deposits in southwestern fujian province china southwest of fujian is one of main ore districts of china thrust controlling mineral deposits model over there means that there may be deep concealed deposits in the overlapping areas of the thrust and refection seismic which has great depth penetration and higher resolution has great potential to delineate these complex structure and give some clues to mineralization in 2015 an experimental 13 8 km 2d reflection seismic survey named fujian 2d was conducted in this region for the data acquisition the designed shot and receiver intervals were 60 m and 20 m respectively and all 691 receivers recorded seismic signals for each shot due to the properties of the tested environment some shot points were re designed but the average fold reached 64 in the middle at more than 10 km distance during the data processing procedure conventional technologies involving statics noise elimination deconvolution and iterative velocity analyses were applied after the pre stack time migration failed to obtain a

estimation of rock mass deformation modulus and strength of jointed hard rock masses using the gsi system abstract rock mass characterization is required for many applications in rock engineering practice including excavation design support design stope design amongst others for these purposes it is necessary to obtain design input parameters such as deformation moduli and strength parameters for numerical modeling although such parameters can ultimately be determined from in situ tests at the preliminary design stage where access to underground is limited the practical way to obtain these parameters is to apply a rock mass classification system to characterize the rock mass and estimate the rock mass properties over the years many classification systems such as rqd rock mass rating q and geological strength index gsi systems have been developed amongst them the q system is widely used for rock support system design and the gsi system is used for estimating design parameters the gsi system is the only rock mass classification system that is directly linked to engineering parameters such as mohr coulomb hoek brown strength parameters or rock mass modulus however the application of the existing gsi system is hindered by the facts that the use of the system is to some extent subjective and requires long term experience in the present study a quantitative approach to assist in the use of the gsi system is presented it employs the block volume and a joint condition factor as quantitative characterization factors the approach is built on the linkage between descriptive geological terms and measurable field parameters such as joint spacing and joint roughness the newly developed approach adds quantitative means to facilitate use of the system especially by inexperienced engineers the gsi system is applied to characterize the jointed rock masses at two underground powerhouse cavern sites in japan gsi values are obtained from block volume and joint condition factor which in turn are determined from site construction documents and field mapping data based on gsi values and intact rock strength properties equivalent mohr coulomb strength parameters and elastic modulus of the jointed rock mass are calculated and compared to in situ test results the point estimate method is implemented to approximate the mean and variance of the mechanical properties of the jointed rock masses it is seen that both the means and variances of strength and deformation parameters predicted from the gsi system are in good agreement with field test data

introduction to special issue on hard rock seismic imaging the exploration of non hydrocarbon resources is receiving increased attention worldwide particularly in terms of renewables e g geothermal energy or minerals both resources are often bound to hard rock environments which normally exhibit a strong degree of heterogeneity including faults and fractures on all scales land seismic surveys for characterizing geothermal reservoirs and mineral deposits are therefore facing the challenge of adapting the methods and tools developed for stratified sedimentary environments to strongly scattering crystalline rocks this comprises not only the pre processing of seismic data but also the imaging steps and furthermore the description and quantification of the resulting images this special issue of geophysical prospecting contains 16 papers resulting from a workshop titled hard rock seismic imaging during the 76th eage conference exhibition 2014 in amsterdam the objective of the workshop was to address all parts of the workflow from modelling and data acquisition design over data processing and imaging to interpretation general concepts and case studies were presented and the workshop attracted a large number of participants from both industry and academia from all over the world a brief introduction to the papers included in this special issue follows divided into the two main categories of the workshop mineral exploration and geothermal prospecting interested readers are also encouraged to check the two earlier special volumes on similar topics by eaton et al 2003 and the references therein and malehmir et al 2012 and the references therein

3d reflection seismic imaging for open pit mine planning and deep exploration in the kevitsa ni cu pge deposit northern finland a 3d reflection seismic survey was conducted over an area of about 9 km 2 at the kevitsa ni cu pge platinum group elements orebody northern finland where open pit mining started in mid 2012 t

cumulate inclusions from k rich magmas roccamonfina volcano italy over 200 plutonic xenoliths have been collected from the pyroclastic deposits of roccamonfina volcano twenty nine representative specimens have been analyzed for major and trace elements and the main mineral phases probed in 20 of these the nodules belong to two cumulate fractionation series a pyroxenite gabbro anorthosite monzonite syenite foidal syenite series and an olivine pyroxenite phlogopite pyroxenite series the various nodule types are not simply related to the stratigraphic position of their host pyroclastics olivine clinopyroxene plagioclase mica biotite and phlogopite k feldspar magnetite apatite and sphene occurring in various proportions and textures represent the cumulus minerals amphibole appears as a secondary product pseudomorphing pyroxene and biotite intercumulus nepheline sodalite hauyne garnet and cancrinite appear in foidal syenites modal and chemical relations suggest that pyroxenites gabbros monzonites syenites and foidal syenites correspond to accumulative material from stage i high k series lavas with respective phenocryst associations cpx trace ol cpx pl trace ol cpx pl trace k spar k spar cpx pl and k spar cpx pl sod the olivine pyroxenites and a single phlogopite pyroxenite specimen appear to be related to stage ii k series ol cpx pl bearing quartz normative trachybasahs the inferred genetic connections however are only partially supported by comparison of phenocryst and cumulus mineral compositions the discrepancies may reflect 1 disequilibrium of nodule and individual lava mineral assemblages due to the contrary motion of different crystal species during fractionation 2 mixing in minor fractionation chambers of crystalline material nodule and magmatic fluids during the eruption of the main magmatic system 3 lower equilibration temperature and higher equilibration pressures of the nodules relative to cogenetic lavas and 4 nodule fractionation from separate episodes of magmas evolved independently from the parental magmas