bathymetric patterns of α and β diversity of harpacticoid copepods at the genus level around the ryukyu trench and turnover diversity between trenches around japan abstract the diversity of harpacticoid copepods was investigated around the ryukyu trench 430 7150 m which lies below an oligotrophic subtropical ocean the diversity which is based on the number of genera and shannon diversity decreased with increasing water depth the community structure of harpacticoids gradually changed as the water depth increased from the bathyal zone to the hadal zone turnover diversity values were equally high between the trench slope trench floor and abyssal plain we compared the harpacticoid assemblage obtained from the ryukyu region with the assemblage from a region around the kuril trench kitahashi et al 2013 turnover diversity values between the two regions diversity were relatively low at shallow depths but they increased with increasing water depth and reached their maximum between the trench floors and abyssal plains these findings indicate that the bathymetric patterns of harpacticoid assemblages differ among regions and that these discrepancies reflect differences in environmental conditions such as primary productivity level

contrasting patterns of α and β diversity in deep sea bivalves of the eastern and western north atlantic abstract we analyzed patterns of and diversity in deep sea bivalves collected by epibenthic sleds from the western north atlantic south of new england and from the eastern north atlantic in the rockall trough porcupine seabight and porcupine abyssal plain in the western north atlantic species diversity measured as the normalized expected number of species shows a unimodal bathymetric trend peaking at mid bathyal depths in the eastern north atlantic diversity increases monotonically with depth reaching a maximum at abyssal depths we used baselga s 2010 metrics to distinguish two separate components of diversity along depth gradients species dissimilarity among sites due to spatial replacement turnover and species loss leading to nestedness we also examined the rank order of nestedness with depth using rodriguez girones and santamaria s 2006 binmatnest the primary difference in diversity between west and east centers on the composition of abyssal communities in the western north atlantic abyssal assemblages are nested subsets of bathyal assemblages in the eastern north atlantic turnover dominates at all depths these very fundamental differences in community structure between the basins may be attributable to differences in food supply which is greater in the eastern north atlantic region sampled poc flux to abyssal depths in the east may not reach levels low enough to depress species diversity as it does in the west in the west the abyssal fauna is largely an impoverished nested subset of the bathyal fauna that shows less endemism and may be maintained partly by source sink dynamics

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

vadose zone flow model parameterisation using cross borehole radar and resistivity imaging cross borehole geoelectrical imaging in particular electrical resistivity tomography ert and transmission radar tomography can provide high resolution images of hydrogeological structures and in some cases detailed assessment of dynamic processes in the subsurface environment through appropriate petrophysical relationships these tools offer data suitable for parameterising and constraining models of groundwater flow this is demonstrated using cross borehole radar and resistivity measurements collected during a controlled vadose zone tracer test performed at a field site in the uk sherwood sandstone both methods show clearly the vertical migration of the tracer over a 200 h monitoring period by comparing first and second spatial moments of changes in moisture content predicted from a numerical simulation of vadose zone flow with equivalent statistics from two and three dimensional ert and cross borehole radar profiles the effective hydraulic conductivity is estimated to be approximately 0 4 m d such a value is comparable to field estimates from borehole hydraulic tests carried out in the saturated zone at the field site and provides valuable information that may be utilised to parameterise pollutant transport models of the site

meiofauna towards the south sandwich trench 750 6300m focus on nematodes abstract meiobenthos excluding foraminifers from the south sandwich trench was studied in sediment samples collected by multiple core muc or multiple grab mg sampling stations were chosen along a depth transect that covered the continental slope and abyssal plain towards the trench water depths from 747 to 6319 m total abundance and biomass of meiobenthos ranged between 354 and 1675 ind 10 cm 2 and between 16 3 and 80 8 g c 10 cm 2 respectively standing stock decreased though not linearly with increasing water depth biomasses and densities were situated above the world ocean s regression line of meiobenthic stocks against water depth and higher on the trench floor 354 930 ind 10 cm 2 18 7 g c 10 cm 2 at 6300 m compared to most other oceans trench regions this observation confirms earlier results from the antarctic continental margins that antarctic meiofauna is characterised by dense populations in which nematodes predominate over the other taxonomic groups 87 98 of total abundance taxonomic investigations at genus level revealed that chromadoridae monhysteridae desmodoridae desmoscolecidae xyalidae and cyatholaimidae were dominant most of the nematode genera in total 94 occurred in all depths with only a slight distinction between the shallow daptonema dichromadora and molgolaimus preferentially at 750 2300 m and deep with tricoma preferentially from 3000 m on the shallow communities were comparable to those from the weddell sea continental margin the sediments at 2300 6300 m harboured in big lines similar compositions as abyssal and trench communities worldwide two main morph clusters were distinguished among the south sandwich trench nematodes plump nematodes with average l w 9 belonging to the taxonomic similar selective deposit feeding genera of the desmoscolecida and comparable slender nematodes l w 26 biomass size class 4 to 2 such as monhystera acantholaimus daptonema dichromadora molgolaimus microlaimus and some species from paracanthonchus mixed among mainly selective and epistratum feeding modes they formed the bulk of the trench community the results did not fit well with the general decrease in standing stock with increasing water depth and distance from the continental shelf similarly nematode size length from 124 to 2991 m biomass from 0 023 to 0 042 g dwt did not show clear bathymetric trends the lack of the usual deep sea trends of structural characteristics of meiofauna in general density total biomass taxon composition and functional attributes of nematodes morphometrics biomass trophic guild structure and maturity index is explained by the particularly complexity of the sedimentary environment of the south sandwich trench which was the result of physical processes turbidites bioturbation activity by invertebrate taxa and food supply along the depth transect

tracking tracer motion in a 4 d electrical resistivity tomography experiment a new framework for automatically tracking subsurface tracers in electrical resistivity tomography ert monitoring images is presented using computer vision and bayesian inference techniques in the form of a kalman filter the trajectory of a subsurface tracer is monitored by predicting and updating a state model representing its movements observations for the kalman filter are gathered using the maximally stable volumes algorithm which is used to dynamically threshold local regions of an ert image sequence to detect the tracer at each time step the application of the framework to the results of 2 d and 3 d tracer monitoring experiments show that the proposed method is effective for detecting and tracking tracer plumes in ert images in the presence of noise without intermediate manual intervention

geophysical monitoring of moisture induced landslides a review author s whiteley js chambers je uhlemann s wilkinson pb kendall jm abstract 2018 the authors geophysical monitoring of landslides can provide insights into spatial and temporal variations of subsurface properties associated with slope failure recent improvements in equipment data analysis and field operations have led to a significant increase in the use of such techniques in monitoring geophysical methods complement intrusive approaches which sample only a very small proportion of the subsurface and walk over or remotely sensed data which principally provide information only at the ground surface in particular recent studies show that advances in geophysical instrumentation data processing modeling and interpretation in the context of landslide monitoring are significantly improving the characterization of hillslope hydrology and soil and rock hydrology and strength and their dynamics over time this review appraises the state of the art of geophysical monitoring as applied to moisture induced landslides here we focus on technical and practical uses of time lapse methods in geophysics applied to monitoring moisture induced landslide the case studies identified in this review show that several geophysical techniques are currently used in the monitoring of subsurface landslide processes these geophysical contributions to monitoring and predicting the evolution of landslide processes are currently underrealized hence the further integration of multiple parametric and geotechnically coupled geophysical monitoring systems has considerable potential the complementary nature of certain methods to map the distribution of subsurface moisture and elastic moduli will greatly increase the predictive and monitoring capacity of early warning systems in moisture induced landslide settings

derivation of lowland riparian wetland deposit architecture using geophysical image analysis and interface detection for groundwater surface water interactions to be understood in complex wetland settings the architecture of the underlying deposits requires investigation at a spatial resolution sufficient to characterize significant hydraulic pathways discrete intrusive sampling using conventional approaches provides insufficient sample density and can be difficult to deploy on soft ground here a noninvasive geophysical imaging approach combining three dimensional electrical resistivity tomography ert and the novel application of gradient and isosurface based edge detectors is considered as a means of illuminating wetland deposit architecture the performance of three edge detectors were compared and evaluated against ground truth data using a lowland riparian wetland demonstration site isosurface based methods correlated well with intrusive data and were useful for defining the geometries of key geological interfaces i e peat gravels and gravels chalk the use of gradient detectors approach was unsuccessful indicating that the assumption that the steepest resistivity gradient coincides with the associated geological interface can be incorrect these findings are relevant to the application of this approach in settings with a broadly layered geology with strata of contrasting resistivities in addition ert revealed substantial structures in the gravels related to the depositional environment i e braided fluvial system and a complex distribution of low permeability putty chalk at the bedrock surface with implications for preferential flow and variable exchange between river and groundwater systems these results demonstrate that a combined approach using ert and edge detectors can provide valuable information to support targeted monitoring and inform hydrological modeling of wetlands

spatial monitoring of groundwater drawdown and rebound associated with quarry dewatering using automated time lapse electrical resistivity tomography and distribution guided clustering dewatering systems used for mining and quarrying operations often result in highly artificial and complex groundwater conditions which can be difficult to characterise and monitor using borehole point sampling approaches here automated time lapse electrical resistivity tomography alert is considered as a means of monitoring subsurface groundwater dynamics associated with changes in the dewatering regime in an operational sand and gravel quarry we considered two scenarios the first was unplanned interruption to dewatering due to a pump failure for a period of several days which involved comparing alert monitoring results before and after groundwater rebound the second involved a planned interruption to pumping over a period of 6 h for which near continuous alert monitoring of groundwater rebound and drawdown was undertaken the results of the second test were analysed using distribution guided clustering dgc to provide a more quantitative and objective assessment of changes in the subsurface over time alert successfully identified groundwater level changes during both monitoring scenarios it provided a more useful indication of the rate of water level rise and maximum water levels than piezometer monitoring results this was due to the piezometers rapidly responding to pressure changes at depth whilst alert dgc provided information of slower changes associated with the storage and delayed drainage of water within the sediment by applying dgc we were able to automatically and quantitatively define changes in the resistivity sections which correlated well with the direct observations of groundwater at site for ert monitoring applications that generate numerous time series the use of dgc could significantly enhance the efficiency of data interpretation and provide a means of automating groundwater monitoring through assigning alarm thresholds associated with rapid changes in groundwater conditions

bedrock detection beneath river terrace deposits using three dimensional electrical resistivity tomography abstract we describe the use of a fully volumetric geophysical imaging approach three dimensional electrical resistivity 3d ert for bedrock detection below mixed sand and gravel deposits typical of fluvial valley fill terraces we illustrate the method through an analysis of terrace deposits of the great ouse river uk where up to 4 m of sand and gravel have filled the valley bottom during the latest pleistocene we use an edge detector to identify the steepest gradient in first derivative resistivity profiles which yields an estimate of bedrock depth verified by drilling to a precision better than 0 2 m average and 0 4 m standard deviation comparison of a range of drilling techniques at the site has revealed that borehole derived interface depths suffered from levels of uncertainty similar to those associated with the 3d ert indicating that the reliability of bedrock interface depths determined using these two approaches is comparable in this case the 3d ert method provides a high spatial resolution that enabled a previously unknown erosional bedrock structure associated with the change from deeper first terrace to second terrace deposits to be identified in the great ouse valley the method provides a relatively quick method to quantify terrace fill volume over large sites to a greater degree of precision than currently available

meiofauna abundance and community patterns along a transatlantic transect in the vema fracture zone and in the hadal zone of the puerto rico trench abstract despite the increasing sampling effort that occurred in the deep sea environment during the last decades knowledge about meiofauna ecology in trenches and fracture zones is still scarce based on the lack of this information a longitudinal transect across the vema fracture zone in the north atlantic was sampled to test whether meiofauna abundances differ between northeast and northwest atlantic basins separated by the mid atlantic ridge also for examination of meiofauna depth pattern the puerto rico trench floor its upper trench slope and the western north atlantic abyssal were investigated in this study meiofauna communities were dominated by nematoda 93 and copepoda 4 the highest total abundance of meiofauna was found in the puerto rico trench and the lowest in the western basin we found significant differences between the eastern and western atlantic basins which were potentially caused by differences in current regimes stronger currents observed in the western basin possibly led to the coarser sediment grain size observed in this region and consequently to the lower abundances of the major groups found there besides grain size the total abundance of meiofauna was significantly correlated with total nitrogen total organic carbon and water depth moreover our study reveals a trend of increasing abundance of total meiofauna with increasing water depth in the puerto rico trench also significant differences between the western abyssal and the puerto rico trench were discovered generally the meiofauna abundance in the investigated area decreased from east to west but increased with increasing water depth in the puerto rico trench due to funnelling of organic sediments increased food availability towards deeper regions in trenches could occur and promote higher abundance

groundwater control for construction purposes a case study from kuwait one of the major rehabilitation projects in kuwait during the 1990s was improvement of the wastewater treatment plant at jahra a town 30 km north of kuwait city the project incorporates construction of a pumping station to collect the sewage via a network of sewer lines throughout the city groundwater occurs 4 m below the ground surface and construction specifications required lowering the groundwater table by 16 m to the foundation grade 20 m below the ground surface open excavation with four stage well point system of dewatering was selected to ensure dry foundation conditions but the system failed to lower the groundwater table down to the desired depth review of site investigation records and recalculation of field hydraulic conductivity resulted in design changes augmenting the well point system with a number of deep wells and sumps to lower the water table down to the foundation grade the paper discusses subsurface conditions and presents an analysis of the cause of failure of the well point system the actual hydraulic conductivity proved to be several folds higher than the calculated one that was determined using hazen s formula it was found that use of hazen s formula led to serious underestimation of field hydraulic conductivity it is advised not to use such formulas without thorough investigation and proper interpretation of borehole data

high resilience of harpacticoid copepods in the landward slope of the japan trench against disturbance of the 2011 tohoku earthquake

a proposed biogeography of the deep ocean floor abstract while there are many generalized schemes representing the biogeographic distribution of life in the deep sea reviewed here a comprehensive analysis has not been undertaken since vinogradova 1979 vinogradova 1997 for the abyssal and belyaev 1989 for the hadal the purpose of this paper is to propose global biogeographic provinces for the lower bathyal and abyssal benthos 800 m depths in order to aid high seas management efforts biological samples from these depths are sparse so delineation of biogeographic provinces was initially hypothesized using oceanographic proxies and examined with documented locations of select benthic marine species these biogeographic provinces were first developed in 2009 via an expert consultation workshop to delineate biogeographic provinces in offshore regions the global open ocean and deep sea goods classification we have refined the goods deep sea classification by incorporating additional high resolution hydrographic and organic matter flux data for the seafloor water mass characteristics temperature and salinity and particulate organic flux to the seafloor were the strongest determinants in the final delineation of provincial boundaries this process resulted in the delineation of 14 lower bathyal and 14 abyssal provinces the bathyal and abyssal classifications presented here should be used with other management tools and analyses e g predictive habitat modeling seamount classifications etc to help determine where marine protected areas should be placed and to minimize the negative impacts of commercial activities in the high seas

electrical resistivity tomography determines the spatial distribution of clay layer thickness and aquifer vulnerability kandal province cambodia despite being rich in water resources many areas of south east asia face difficulties in securing clean water supply this is particularly problematic in regions with a rapidly growing population in this study the spatial variability of the thickness of a clay layer controlling surface groundwater interactions that affect aquifer vulnerability was investigated using electrical resistivity tomography ert data were acquired along two transects showing significant differences in the imaged resistivities borehole samples were analyzed regarding particle density and composition and linked to their resistivity the obtained relationships were used to translate the field electrical resistivities into lithologies those revealed considerable variations in the thickness of the clay layer ranging from 0 m up to 25 m geochemical data highlighting zones of increased ingress of surface water into the groundwater confirmed areas of discontinuities in the clay layer which act as preferential flow paths the results may guide urban planning of the phnom penh city expansion in order to supply the growing population with safe water the presented approach of using geophysics to estimate groundwater availability accessibility and vulnerability is not only applicable to kandal province cambodia but also to many other areas of fast urbanization in south east asia and beyond

bedrock detection using 2d electrical resistivity imaging along the peikang river central taiwan article i nfo we use the two dimensional 2d electrical resistivity imaging eri method to detect the contact between sediment and bedrock in a modern fluvial system we performed eight 2d electrical resistivity surveys along the peikang river in kuohsing area central taiwan with a pole pole array of 1 m electrode spacing to produce a spatial resolution of about 1 m the resistivity data were inverted into subsurface electrical structures using the least squares inversion techniques then the contact between the bedrock and sediment was found by using an image processing technique called laplacian edge detection led which represents an objective approach in interpreting various geophysical images numerical modeling demonstrates that isoresistivity lines are not in good agreement with the hypothetical interfaces between the bedrock and sediment but the zero lines of the laplacian operation are strikingly accurate our results indicate a well defined boundary in the resistivity structure that can be used to estimate the quantity of sediments covering bedrock thus highlighting the utility of this technique in studies of landscape evolution sediment transport and sediment budgets

identification of potential for methane ignition by rock friction in australian coal mines abstract the relative propensity for the different rock types in australian underground coal mines to ignite methane bearing atmospheres by frictional contact either with mining equipment or with other rock materials has been evaluated by laboratory testing using an instrumented rotating wheel apparatus a five point incendivity categorisation has been developed for the rocks tested and the results compared to petrographic composition mineralogy and related chemical properties recent experience with ignitions in new south wales collieries has also been taken into account with the progressive decline in ignitions from other sources frictional effects are now the most common source of methane ignition in modern underground coal mines conglomerates lithic or quartzose sandstones with low clay and carbonate contents and siliceous cherty tuffs appear to represent the most potentially incendive materials in roof and floor strata along with siliceous or pyritic impregnations that may occur in the coal seam itself temperatures in excess of 1500 c may be developed within less than 1 s during rock on rock contacts with ignitions emanating from the contact point or related heat trail rather than from incandescent particles sparks ejected during the friction process the average temperature and the coefficient of dynamic friction developed during rock on rock testing also appear to be related to frictional incendivity characteristics

assessment of methane ignition potential by frictional processes from australian coal mine rocks a method for categorising the potential of different rocks to ignite methane gas in mine atmospheres has been developed for a suite of sedimentary and igneous samples from australian coal mine areas based on rock on rock friction behaviour in a rotating wheel test rig the five point ignition potential categorization igcat value is derived from the occurrence of ignitions or non ignitions in a gas chamber with a 7 methane atmosphere when a sample of the rock is pressed with a constant load against a rotating wheel of the same material at contact speeds of 2 2 3 7 and 5 1 m s

quantitative mineralogy of sandstones by x ray diffractometry and normative analysis abstract quantitative x ray diffraction normative calculation and whole rock chemical analysis have been compared for permo triassic quartz lithic to litho feldspathic sandstones from eastern australia the quantitative xrd technique provides mineralogical percentages that correlate well with the chemical composition of the sandstones and also with most of the mineral percentages derived from normative calculation the need for assumptions on potassium distribution between minerals provides a limitation on estimates of k feldspar and illite using the normative technique although these can be improved on a sample specific basis if necessary using complementary thin section observations or qualitative x ray diffractograms quantitative xrd analysis possibly indicates a small proportion of amorphous material in some of the sandstones especially materials with abundant lithic fragments or clay minerals but the proportion of any amorphous material overall is probably negligible both quantitative xrd and normative calculation avoid problems associated with sample heterogeneity or operator inconsistency that may affect point counting of thin sections they can also be used to provide quantitative information on sediments with abundant rock fragments or matrix components the actual mineralogy of which is not resolvable in conventional microscope investigations

four dimensional imaging of moisture dynamics during landslide reactivation landslides pose significant risks to communities and infrastructure and mitigating these risks relies on understanding landslide causes and triggering processes it has been shown that geophysical surveys can significantly contribute to the characterization of unstable slopes however hydrological processes can be temporally and spatially heterogeneous requiring their related properties to be monitored over time geoelectrical monitoring can provide temporal and volumetric distributions of electrical resistivity which are directly related to moisture content to date studies demonstrating this capability have been restricted to 2d sections which are insufficient to capture the full degree of spatial heterogeneity this study is the first to employ 4d i e 3d time lapse resistivity imaging on an active landslide providing long term data three years highlighting the evolution of moisture content prior to landslide reactivation and showing its decline post reactivation crucially the time lapse inversion methodology employed here incorporates movements of the electrodes on the unstable surface although seasonal characteristics dominate the shallow moisture dynamics during the first two years with surficial drying in summer and wetting in winter in the months preceding reactivation moisture content increased by more than 45 throughout the slope this is in agreement with independent data showing a significant rise in piezometric heads and shallow soil moisture contents as a result of prolonged and intense rainfall based on these results remediation measures could be designed and early warning systems implemented thus resistivity monitoring that can allow for moving electrodes provides a new means for the effective mitigation of landslide risk

deposit feeding by the pliocene deep sea macrobenthos synchronized with phytodetritus input micropaleontological and geochemical evidence recorded in the trace fossil phymatoderma abstract the present study consists of the microscopic and geochemical analyses of specimens of the trace fossil phymatoderma from the pliocene deep marine strata shiramazu formation japan the aim of this paper is to assess whether benthic pelagic coupling functioned in the ancient ocean as it does in the modern ocean various types of microfossils e g coccoliths diatoms planktonic foraminifera and radiolaria were detected by sem observation of fecal pellets of phymatoderma among these plankton coccolithophores are considered to have been the most important dietary source for the phymatoderma producing echiuran worm because excreted tuffaceous fecal pellets are occasionally found to be composed exclusively of coccoliths elemental analysis using the sem eds system revealed that cao which is probably derived from the microfossils of calcareous plankton i e coccoliths and planktonic foraminifera was abundant in the tuffaceous fecal pellets considering the obtained microscopic and geochemical evidence it is most likely that the echiurans deposit feeding activity was synchronized with an episodic probably seasonal coccolithophore bloom deposition on the deep sea floor such a mode of feeding may have facilitated the effective uptake of freshly deposited phytodetritus the present study provides geologic evidence for benthic pelagic coupling in the pliocene epoch in addition based on the integration of the obtained results and reinterpretations of the existing data the present study further supports the possibility that the modern type benthic pelagic coupling had established during the cretaceous period

effect of the 2011 tohoku earthquake on deep sea meiofaunal assemblages inhabiting the landward slope of the japan trench abstract meiofaunal assemblages inhabiting the landward slope of the japan trench water depth 120 5600 m were examined 4 5 months and 1 5 years after the 2011 tohoku earthquake off sanriku miyagi prefecture northeast japan two key parameters were compared before 24 30 years and after 4 5 months in 2011 and 1 5 years in 2012 the earthquake a the bathymetric pattern and b the vertical distribution of meiofauna in the sediments differences in meiofaunal densities and associated bathymetric patterns were not detected before and after the earthquake however the vertical profiles of meiofauna in the sediments differed at some stations the highest meiofaunal densities occurred in the subsurface layers in 2011 at some stations with these subsurface peaks being no longer present in 2012 at these stations the assemblage structure at the higher taxon level differed between 2011 and 2012 with copepod density increasing in 2012 therefore copepod abundance appeared to decrease because of the effect of earthquake related events e g rapid sedimentation induced by the turbidity current these changes in meiofaunal vertical profiles and assemblage structures detected after the earthquake were probably caused by an increase in organic matter content in the topmost layers these results indicate that major disturbances to deep sea sediments mainly influenced the vertical distribution and assemblage structure of meiofauna after the 2011 tohoku earthquake whereas meiofaunal densities remained similar or quickly recovered within 4 5 months of the event

diagenetic quartz and amorphous silica in new zealand coals new zealand coal seams late cretaceous miocene lignite semi anthracite contain numerous and varied occurrences of diagenetic quartz and amorphous silica early diagenetic silicifications include sub horizontal and laterally extensive quartz mineralized bands micro and megascopic euhedral quartz crystals dispersed or concentrated in layers and silicified in situ tree stumps late diagenetic forms include sub horizontal quartz mineralized bands mostly 1 m in length and fracture infillings the origins of the silica remain uncertain but leached basement rocks and coal measure sediments and siliceous phytoliths within the coal forming plants are possible sources the silicification of coal seams may have significant implications for exploration mining and geological studies

use of mineralogical analysis in geotechnical assessment of rock strata for coal mining abstract the fundamental geotechnical properties of sedimentary rocks from the coal bearing sydney basin of new south wales australia including density porosity water absorption and moisture content as well as compressive strength have been related to the mineralogy of the materials as determined by quantitative x ray diffraction of powdered rock samples and processing by the rietveld based siroquant technique the results show for example that the overall proportions of clay minerals in the rocks as well as the types of clay minerals present affect properties such as water absorption and moisture content the presence of clay minerals also adds to the dry strength of silica cemented quartz sandstones however the strength of finer grained mudrocks is inversely related to the total percentage of clay minerals correlations have been established between the deterioration or slaking behaviour of mudrocks in water and their clay mineral content based on either simple immersion tests or on more sophisticated slake durability index determinations these relationships may be of significance in understanding the longer term behaviour of rock strata when exposed in different types of mining operations the propensity of different rocks to ignite methane in underground mines by frictional effects has also been shown to depend on the mineralogy of the rock materials whether determined by point counting of thin sections or by rietveld based xrd analysis abundant quartz feldspar and rock fragments in sandstones for example increase the likelihood of frictional ignitions whereas clay minerals and especially carbonates in the rock reduce the frictional ignition potential pyrite in the rocks if present also increases the ignition risk pyrite undergoes exothermic oxidation at high temperatures whereas other minerals respond by simple heating due to rock on rock or pick on rock friction processes

an engineering site investigation using non invasive geophysical approach subsurface geological formation is essential to validate design assumptions for the construction of deep engineering structures especially in the weathered terrains the geological formation can be delineated using resistivity values through an electrical survey however the subsurface resistivity alone is ambiguous to interpret the subsurface geological units as part of an ongoing investigation to select the key methods towards this end an integrated geophysical survey through a combination of electrical resistivity tomography ert induced polarization ip magnetic method and joint profile method jpm was carried out in a weathered terrain of south huizhou china resistivity ip and magnetic data were obtained using a variety of survey parameters subsurface resistivity was calibrated with upfront boreholes lithology to constrain geological formation into four discrete layers such as topsoil cover with resistivity 2 3257 m highly weathered layer having resistivity 2 636 m partly weathered layer with resistivity range 448 1204 m and unweathered bedrock having resistivity 791 116 497 m the integration of ert with ip magnetic and jpm delineated four faults namely f1 f2 f3 and f4 and several localized fractures the weathered layer fractures and faults were marked as the weakest zones for engineering projects whereas the unweathered fresh bedrocks were identified as the most appropriate locations for the construction of deep structures in the study area the weakest zones unsuitable for engineering structures were delineated as the most appropriate places of groundwater occurrence in the studied area revealed by low resistivity ranging from 2 to 1204 m and overlapped by low chargeability less than 14 8 ms this non invasive geophysical approach suggests the most suitable locations highly significant not only for the future construction of engineering structures but also the exploitation of groundwater resources in the investigated area