fluid inclusion characteristics and geological significance of the xi ao copper tin polymetallic deposit in gejiu yunnan province abstract the newly discovered xi ao cu sn polymetallic deposit is located in the inner alteration zone of the laochang kafang granite edge in gejiu yunnan province the mineralization process of this deposit can be divided into four stages cassiterite and chalcopyrite mainly formed at stages ii and iii respectively fluid inclusions at different stages were studied by petrography microthermometry and laser raman spectrometry five fluid inclusion types are observed microthermometry results revealed that the ore forming fluid evolved from high temperature with low to intermediate salinity to low temperature with low salinity at stage i the fluid was under near critical conditions and then separated into coexisting liquid and vapor phases at stage ii finally the fluid was boiling and immiscible at stage iii a meteoric fluid mixing process was also observed at this stage laser raman spectra identified ch4 at the skarn and mineralization stages combined with other geological features the deposit was concluded to have formed under a relatively reduced environment the co2 component abruptly increased at stage iii and probably originated from the exterior fluorine may play an important role in mineralization cassiterite and chalcopyrite were mainly deposited at 340 440 and 300 400 c under pressures of 18 50 and 12 36 mpa respectively boiling and immiscibility are probably the main reason for mineral deposition the deposit of cassiterite and chalcopyrite showed similar salinities but higher temperatures than other mineralization types of deposits in the gejiu area this finding indicated that the study deposit probably represents the high temperature part of the gejiu mineralization system thereby benefiting mineral explorations in the gejiu area

constraining the distribution of elements and their controlling factors in the zhaojikou pb zn ore deposit se china via fractal and compositional data analysis abstract the distribution of elements in soil is affected by various natural processes and therefore it is essential that exploration geochemists are able to recognize whether an elemental concentration is related to mineralization or other processes this research aimed to recognize the elemental distribution and its controlling factors around the zhaojikou pb zn ore deposit se china via fractal and compositional data analysis firstly histograms over the raw data and log ratio transformations were used to check whether the concentration data followed a normal distribution or not the concentration distribution maps of elements were then generated via spretrum area fractal plot to show the spatial relationships afterward the inter relationships among different elements were studied through robust principal component analysis based on compositional data theory the factors controlling the distribution of elements were discussed and geochemical indices were proposed for future exploration finally a comprehensive anomaly map was generated to show important prospecting areas results showed how the interpretation of distributions of elements was enhanced due to the application of data log ratio transformation in univariate and multivariate analysis compared to the use of raw data the histograms based on isometric log ratio performed best among the three log ratio transformations the concentration distribution maps showed three anomalous areas at the surface it clearly allowed identifying the relationships between the elements and their possible source patterns area i with anomalous assemblage of pb zn ag cu cd corresponded to the current known ore deposits while area ii with anomalous assemblage of pb zn ag cu cd may indicate the occurrence of new potential base metal pb zn ore bodies and area iii with anomalous assemblage of w as sb may indicate the occurrence of new potential au mineralization ore occurences the robust biplot of pca shows that the distributions of elements of interest were generally controlled by three geological processes pb zn ore forming process au mineralization and weathering lead zn ag cu and cd were affected mainly by pb zn ore forming processes w sb and as were affected mainly by au mineralization whereas al2o3 k2o rb ba sr na2o cao mgo and sio2 were affected to a greater extent by weathering processes sulphur a mineralizing agent was controlled by the ore forming processes being affected greatly by weathering finally we proposed pb 160 ppm zn 120 ppm ag 193 ppb cu 50 ppm cd 210 ppb w 5 ppm as 25 ppm sb 3 5 ppm and s 120 ppm as geochemical indices based on concentration area fractal model analysis for future surficial geochemical prospecting in the zhaojikou district

stream sediment geochemical data analysis for district scale mineral exploration targeting measuring the performance of the spatial u statistic and c a fractal modeling abstract recognition of mineralization related geochemical footprints and modeling their multi element dispersion patterns are important aspects to consider when vectoring toward undiscovered ore deposits the collection analysis and interpretation of stream sediment geochemical data together make an exploration method that has proven to be successful at the district scale mineral exploration targeting identifying the possible sources of stream sediment geochemical anomalies and mapping evidence i e footprints of the underlying ore forming processes however are not trivial tasks this is because stream sediment samples represent transported material reflecting the entire geology upstream from the sample locations furthermore indicator element distribution patterns are commonly strongly affected by local factors such as regolith topographic gradient vegetation density and or climate therefore there is a need for finding a better geochemical anomaly separation method regarding the nature of geochemical data obtained from the area sampled the main objectives of this study were 1 evaluating and comparing the spatial u statistic and concentration area fractal modeling methods of anomaly identification both amenable to spatial analysis for recognizing geochemical footprints of porphyry copper mineralization and 2 measuring their performance in the context of district scale exploration targeting in an area located in southeast iran subsequently the methods were first evaluated on a dataset of element contents to decompose anomalous populations finally the geochemical model that proved more efficient with respect to predicting the known mineral deposits was integrated with additional evidence maps to delineate exploration targets our evaluation of the resulting geochemical targeting model demonstrated that the targets derived from this method are robust and worthy of follow up exploration

modeling singular mineralization processes due to fluid pressure fluctuations abstract mineralization in the earth s crust can be regarded as a singular process resulting in large amounts of mass accumulation and element enrichment over short time or space scales the elemental concentrations modeled by fractals and multifractals show self similarity and scale invariant properties we take the view that fluid pressure variations in response to earthquakes or fault rupture are primarily responsible for changes in solubility and trigger transient physical and chemical variations in ore forming fluids that enhance the mineralization process based on this general concept we investigated mineral precipitation processes driven by rapid fluid pressure reductions by coupling mineralization to a cellular automaton model to reveal the nonlinear mechanism of the orogenic gold mineralization process using simulation in the model fluid pressure can increase to the rock failure condition which was set as lithostatic pressure at a depth of 10 km 270 mpa due to either porosity reduction or dehydration reactions rapid drops in pressure resulting from fault rupture or local hydrofracture may induce repeated gold precipitation the geochemical patterns generated by the model evolve from depletion to enrichment patterns and from spatially random to spatially clustered structures quantified by multifractal models and geostatistics results show how metal elements self organize to form high metal concentration patterns displaying self similarity and scale invariance these transitions are attributed to the growth and coalescence of sub networks with different fluid pressures up to the percolation threshold resulting in a wide range of fluid pressure reductions and gold precipitation in the form of clusters the results suggest that cyclic evolution of fluid pressure and its effects on gold precipitation systems can effectively mimic the repeated mineralization superposition process and generate complex geochemical patterns characterized by a multifractal model the nonlinear behavior exhibits scale invariance and self organized critical threshold where mineral phase separations result from fluid pressure reductions associated with fault failure

physicochemical study of skarn formation in pelitic rock costabonne peak area eastern pyrenees france the costabonne skarn complex was emplaced in the lower part of the cambrian canaveilles formation eastern pyrenees in contact with a hercynian granitic stock skarns have developed from calcium poor 0 99 with minor co2 ch4 n2 h2 o2 h2s hcl and hf ca na and k were the most abundant cations temperature and pressure conditions are estimated to be at least 550 c and 1 7 to 2 0 kb respectively the totality of the observed transformations may be described in the system cao k2o sio2 al2o3 mgo h2o with the minerals quartz muscovite phlogopite tremolite diopside grossular k feldspar and anorthite with cao and k2o taken as perfectly mobile components sio2 al2o3 and mgo as determining inert components and h2o as excess component the reactions leading to the skarn formation can be represented in a mu cao mu rm k 2 o diagram the succession of zones is shown to take place with increasing cao from the schist z0 up to the garnet zone z4 the nature of the feldspar plagioclase or k feldspar depends on the value of mu rm k 2 o relative to cao

feldspar influenced rock rheologies progressive fracture subsequent cataclasis and syntectonic alteration of feldspar to phyllosilicates transformed a massive granite into a quartz mica phyllonite during early tertiary deformation in a 20 30 m wide shear zone in southeastern arizona the ductile deformation proceeded at temperatures and pressures approximating middle to upper crustal levels most of the deformation was taken up by the feldspar and its alteration products quartz deformed by both brittle fracture and crystal plastic mechanisms these results show that under certain temperature pressure strain rate conditions feldspars are weaker than quartz the observed deformation mechanisms indicate that the brittle to ductile transition in fault zones is not simply a function of the onset of temperature activated plastic deformation in quartz nor of the frictional behavior of rocks as inferred in the familiar strength vs depth curves it is more likely that the transition is complex and depends on a variety of parameters one such factor delineated in this study is the fracture and fracture facilitated syntectonic alteration of feldspar under hydrated conditions

gis based mineral potential modeling by advanced spatial analytical methods in the southeastern yunnan mineral district china this paper demonstrates a modeling procedure of mineral potential mapping based on singularity theory and further presents an idea to look into metallogeny of sn cu polymetallic deposits in southeastern yunnan mineral district china by applying a localized regression method mineralization is a typical cascade process generally accompanied by irregular geological geochemical and geophysical signatures singularity index as an efficient anomaly analytical tool helps to identify anomalies as well as characterize formation processes of these anomalies in this study the singularity based mineral potential mapping method was utilized to characterize hydrothermal mineralization associated with magmatic tectonic and sedimentary processes in this district based on the results a mineral prospectivity model was constructed to delineate target areas in addition to mineral prospectivity controlling effects of geo processes on mineralization are spatially non stationary geographically weighted regression analysis was thus employed to investigate these spatially varied controlling effects and it has contributed to improve understanding to local metallogeny in the study area results of the spatial analysis presented can be used to guide following stages of mineral exploration in the district

a novel approach for extraction of gaoshanhe group outcrops using landsat operational land imager oli data in the heavily loess covered baoji district western china abstract we studied the applicability of landsat operational land imager oli data for extraction of gaoshanhe group outcrops in a heavily loess covered area in the northern baoji district of china which is always a crucial but challenging issue in geological remote sensing mapping an integrated approach was employed to process the remote sensing data first the interpretation target area of interest was clipped using certain slope and elevation difference thresholds topographical analysis second band ratio b4 b2 and fractal summation algorithms were conducted in succession to extract the bedrock induced anomalies third spatial clumping and hot spot analysis were performed in order to eliminate residual false anomalies and finally we introduced high resolution worldview 2 data for visual interpretation and further spectral analysis the findings show that the rocky outcrops were somewhat spectrally indistinguishable and they were identified mainly due to their generally moderate degree of spatial clustering thirteen anomalous pixels were extracted from nearly 200 000 pixels covering the study area and our field reconnaissance verified the results this research constitutes the first useful case study on the applicability of landsat data derived lithology interpretation in china s loess plateau region

late precambrian crustal extension preserved in fries fault zone mylonites southern appalachians mesoscopic and microscopic kinematic indicators throughout ca 690 ma peralkaline plutonic rocks in the footwall of the fries fault zone blue ridge province southwest virginia record dip slip normal southeast down movement under greenschist facies deformation conditions mylonites cataclasites and associated precursor mineralized fractures and dikes are consistent in geometry and movement history with extensional faulting although over 50 km of northwest directed thrust movement was proposed by earlier workers for parts of the 300 km long rockfish valley fries fault system along major sections of the fries fault the only concrete evidence for thrusting is in the form of late stage shear bands that crosscut the earlier extension related mylonitic fabric we suggest that the entire rockfish valley fries fault zone formed during the late precambrian extension of the now eastern margin of the north american craton to create the iapetus ocean and was locally reactivated as a thrust zone during paleozoic time

quantifying tooth variation within a single population of albertosaurus sarcophagus theropoda tyrannosauridae and implications for identifying isolated teeth of tyrannosauridsthis article is one of a series of papers published in this special issue on the theme albertosaurus documenting variation in theropod dinosaurs is usually hindered by the lack of a large sample size and specimens representing several ontogenetic stages here variation within 140 disassociated and seven in situ tyrannosaur teeth from the upper cretaceous lower maastrichtian monodominant albertosaurus sarcophagus theropoda tyrannosauridae bonebed is documented this sample represents the largest data set of teeth from one population of a sarcophagus containing both adult and juvenile specimens tooth variation was assessed using multivariate analyses principal component discriminant and canonical variate analyses heterodonty in the teeth of a sarcophagus contributes to the large amount of variation in the data set premaxillary teeth are significantly different from maxillary and dentary teeth but there is no quantifiable difference between a priori identified maxillary and dentary teeth juvenile and adult teeth of a sarcophagus show apparent quantitative differences that are size dependen

gis based 3d prospectivity mapping a case study of jiama copper polymetallic deposit in tibet china abstract this paper reports a deposit scale gis based 3d mineral potential assessment of the jiama copper polymetallic deposit in tibet china the assessment was achieved through a sequential implementation of metallogenic modelling and 3d modelling of geology geochemistry and prospectivity a metallogenic model for the jiama deposit and 3d modelling workflow were used to construct multiple 3d layers of volumetric and triangular mesh models to represent geology geochemistry and ore controlling features in the study area a gis based 3d weights of evidence analysis was then used to estimate the subsurface prospectivity for cu mo orebodies in the area which led to the identification of three prospective deep seated exploration targets additionally the geochemical modelling indicates three potential fluid flow pathways based on the 3d zonation of major geochemical elements and their ratios particularly the zn pb ratios which support the results of the weights of evidence model

modeling of cu au prospectivity in the carajas mineral province brazil through machine learning dealing with imbalanced training data abstract machine learning ml is becoming an appealing tool in various fields of earth sciences especially in mineral prospectivity mapping mpm to support mineral exploration ml algorithms are designed to assume a relatively balanced amount of training data for the estimation of the decision boundaries between the classes of interest i e in mpm mineralized and non mineralized locations however in mpm the numbers of mineralized and non mineralized locations are naturally imbalanced as the number of known mineral deposit occurrences as a proxy of mineralized or positive class are naturally much smaller than the number of non mineralized locations the negative class the use of imbalanced data leads to difficulties in the training of ml models for mpm due to the learning bias towards the features of the predominant i e negative class in the present study using support vector machine for cu au prospectivity modeling in the carajas mineral province brazil we evaluated the effects of synthetic minority over sampling technique smote which addresses the issue of imbalanced training data on the performance of mpm the original training data for the positive i e minority class was modified by over sampling the mineralized locations using smote and by randomly under sampling the non mineralized locations at different proportions producing 400 training datasets with proportions of mineralized to non mineralized samples ranging from 600 30 to 30 600 each of these individual training datasets was used to evaluate the performance of mpm under different proportions of mineralized to non mineralized samples the performance of each prospectivity model was objectively evaluated using the f1 score and the success rate curve the results show that smote can significantly increase the performance and the spatial efficiency of mpm the main differences between the performances of the derived prospectivity models illustrate the sensitivity of mpm to the number of samples and distribution of classes in the training data according to the results better performance is achieved using smote when the prospectivity models are trained with an equal number of mineralized and non mineralized samples the best prospectivity model trained with a modified dataset with 600 600 proportion of mineralized to non mineralized samples resulted in 100 classification of the training mineralized locations and almost 80 of the testing mineralized locations and outlined only 7 of the study area as prospective

mineral systems approach applied to gis based 2d prospectivity modelling of geological regions insights from western australia abstract gis based 2d prospectivity modelling of three greenfield geological regions of western australia namely the west arunta orogen west musgrave orogen and gascoyne province was implemented for a range of deposit types including orogenic and intrusion related gold volcanic sediment hosted base metal sulfides magmatic nickel copper and magmatic platinum group element sulfides iron oxide copper gold tin tungsten igneous and metamorphic related rare earth elements surficial uranium and unconformity related uranium conceptual mineral systems models were generated to identify the targeting criteria the inputs to the models were the spatial proxies derived from 1 100 000 to 1 500 000 scale public domain data the results showed similar prospectivity patterns for all of the targeted deposit types except sediment hosted uranium and surficial uranium deposit types once a favourable geodynamic architecture is established it can sustain different mineral systems and produce diverse deposit types depending on the nature of ligands in the source regions and physical chemical environment in the trap regions through repeated reactivation in the subsequent geological history a model is proposed to explain the formation of different deposit types at different stages of tectonic evolution of a province the implication for gis based 2d prospectivity modelling at the scale of geological region is that the prospectivity model may not be deposit type specific further prospectivity modelling should be carried out sequentially at progressively finer scales regional to district to camp scale using only the targeting criteria that are relevant at the specific scale to delineate targets for specific deposit types

electromagnetic methods for mineral exploration in china a review abstract electromagnetic methods play an important role in mineral exploration and are widely used in the search for metallic resources such as copper molybdenum lead zinc bauxite uranium etc in this paper we focus on reviewing the application and development of electromagnetic methods such as magnetotelluric mt audio magnetotelluric amt controlled source audio magnetotelluric csamt and transient electromagnetic tem respectively this paper also presents examples of electromagnetic methods applied to the exploration of metal deposits on land airborne and in the marine environment furthermore we discuss the future development of electromagnetic prospecting tools the data processing modeling and inversion interpretation and their application in complex geological environments the future of successful mineral exploration using em methods will be focused on concealed and deep target exploration and possibly one day on resources on the seafloor

multivariate analysis of isolated tyrannosaurid teeth from the danek bonebed horseshoe canyon formation alberta canada1 a significant number of fossil remains of the hadrosaurid edmontosaurus have been recovered from the danek bonebed horseshoe canyon formation upper cretaceous alberta bones from theropod dinos

granite related ore deposits an introduction a symposium on mineralization associated with granitic magmatism was held within the framework of the 33rd igc in oslo norway in august 2008 while our initial idea was to bring together field experimental and theoretical studies in order to review and summarize the current ideas and recent progress on granite related mineralization systems we were caught by surprise realizing that participants were inclined to focus more on ore deposits related to granitic magmatism this spontaneous shift from granites the major intended focus of the symposium to mineralization associated with them spawned the idea for a special issue on this theme and ultimately to the nine papers assembled here chosen from about 60 scientific contributions at the symposium around twenty oral presentations were given and forty posters were presented at the meeting the 60 papers were grouped according to the current main granite related ore systems as follows granite pegmatite skarn and greisen veins porphyry orogenic gold intrusion related epithermal and porphyry related gold and base metal iron oxide copper gold iocg and special case studies importance of granite related mineralization systems diversity of mineralization styles and related

introduction to the special issue gis based mineral potential modelling and geological data analyses for mineral exploration this introduction provides an overview of the procedures involved in mineral potential modelling the papers included in this special issue are also summarized

correlation between mineralization intensity and fluid rock reaction in the xinli gold deposit jiaodong peninsula china constraints from petrographic and statistical approaches abstract the jiaodong peninsula the most productive gold province in china is dominated by jiaojia type gold deposits that formed at ca 120 ma the deposits are characterized by widespread alteration and mineralization resulted from fluid rock reactions in the footwall of regional faults it is known that the interrupted appearance of continuous mineralization zones and barren zones along regional faults is controlled by changes in the dip direction and dip angle of these faults which can cause local dilational sense in the continuous mineralization zone intensive fluid rock reactions occurred yet whether and how the fluid rock reaction impacted on the mineralization intensity are not well constrained in this study we selected the xinli jiaojia type gold deposit associated sanshandao cangshang fault located on the northwest margin of the jiaodong peninsula to examine in detail the distribution of orebody parameters and to observe the mineralization occurrences we applied the number size fractal model and the lacunarity method to quantify the distribution of gold concentration along drifts with the goal of clarifying the ambiguities noted above the drifts in continuous mineralization zones can be divided into stable and unstable types according to lateral changes in the dip direction and dip angle of the sanshandao cangshang fault stable and unstable drifts share several common features 1 statistical results show that changes in the dip direction and dip angle of this fault bear almost no relationship to the thickness or grade thickness of the orebody 2 mineralization along drifts is most intense at some distance from the fault plane rather than at locations immediately adjacent to the fault plane where fracturing is most extensive and according to fluid infiltration theory would be the most likely regions of intense mineralization 3 gold bearing sulfide pods and veinlets in the alteration zone commonly possess irregular and corroded boundaries that are considered to be an indicator of fluid rock reactions 4 the threshold the gold concentration that divides a segment with a lower fractal dimension in a lower concentration range from one with a higher fractal dimension in a higher concentration range and the lacunarity the parameter that evaluates the evenness of high gold concentration distribution show positive and negative relationships respectively to the thickness and grade thickness of a drift we thereby argue on the basis of these features that fluid rock reactions were an important factor responsible for the mineralization upgrade in continuous mineralization zones an increase in the threshold and a decrease in the lacunarity indicate that fluid rock reactions causing gold precipitation are more intensive and more evenly distributed throughout the footwall for better mineralization these phenomena suggest that fluid rock reactions responsible for the gold precipitation possibly own the characteristics of spatial self organization mechanism which is widely developed in various geological fluid rock reaction processes

mapping singularities with stream sediment geochemical data for prediction of undiscovered mineral deposits in gejiu yunnan province china abstract this paper proposes the concept of singularity for characterizing hydrothermal mineralization processes a singular physical process may result in anomalous amounts of energy release or material accumulation within a narrow spatial temporal interval mineralization can be considered as a type of singular process due to large amounts of material accumulation and element enrichment a spatial singularity mapping technique is developed based on the local singularity involved in the context of multifractal theory it assembles geochemical map at different scales and calculates an index indicating the scaling characteristics of enrichment and depletion of geochemical concentration at multiple scales this index was used for quantifying spatial singularity of mineralization associated geochemical anomalies a case study for the gejiu tin polymetallic mineral district yunnan province china demonstrates that the concepts of singularity and the singularity mapping technique are applicable and useful for delineating anomalies caused by mineralization and for predicting the locations of undiscovered mineral deposits

delineation of gold mineralized zones using concentration volume fractal model in qolqoleh gold deposit nw iran article i nfo the aim of this study is to delineate and recognize the different gold mineralized zones based on surface and subsurface lithogeochemical au data utilizing concentration volume c v model in the qoloqoleh gold vein deposit nw iran c v modeling outlined six geochemical populations and four mineralized zones for au element based on log log plot which was correlated with the mineralized veins from geological data ex tremely mineralized veins are higher than 14 12 ppm in au grade which are correlated with surface weath ered zone by oxidized pyrites the main phase of gold mineralization where au grade typically ranges between 3 98 and 14 12 ppm is associated with thick quartz veins moderately and weakly mineralized zones ranging from 0 354 to 3 98 ppm au derived by c v model were correlated with narrow quartz veins that contain minor sulfides in the deposit barren host rocks obtained by c v modeling were correlated with barren quartz veins in the deposit the results were compared with a geological model showing a strong positive correlation between mineralized zones and quartz sulfide veins hosted by meta volcanic rocks and sericite schist results examined via the c v fractal model illustrate that the interpreted zones based on the fractal model mineralogical sem and epma analyses have strong correlation with highly and moderately silicic mineralized veins consisting of sulfides and au to certify this a logratio matrix was employed to validate the c v fractal model for au and two lithological units namely meta volcanic rocks and sericite schists indicating the overall accuracy of 0 56 and 0 58 respectively

the danek edmontosaurus bonebed new insights on the systematics biogeography and palaeoecology of late cretaceous dinosaur communities1 vertebrate bonebeds are rich sources of palaeontological information throughout the world rogers et al 2007 and they have long been sources of information on dinosaur anatomy behaviour ecology growth and variability although dinosaur dominated bonebeds have been known in alberta for a long time brown 1919 sternberg 1970 they received relatively little attention during the first seven decades that dinosaurs were collected in the province this was primarily because collectors came to alberta for the relatively common well preserved articulated dinosaur skeletons that produced both new species and spectacular museum displays currie 1981 1987 since the beginning of the 1980s the dinosaur bonebeds of dinosaur provincial park have received considerable attention currie and dodson 1984 visser 1986 ryan 1992 andersen 2000 ryan et al 2001 ryan 2003 ryan and russell 2005 eberth and getty 2005 however younger bonebeds from farther north in the province have enjoyed less attention ryan et al 1995 1998 2011 eberth et al 2013 two notable exceptions are the albertosaurus bonebed near dry island buffalo jump provincial park currie and koppelhus 2010 and the pachyrhinosaurus lakustai bonebed along pipestone creek near grande prairie currie et al 2008 in and around edmonton in particular dinosaur remains have been largely ignored in the published literature bell and campione 2014 despite easy access to outcrops along the north saskatchewan river and its associated streams and creeks this special issue of the canadian journal of earth sciences increases our knowledge of edmonton s urban dinosaurs especially the iconic and serendipitously named hadrosaurid

stratigraphy and tectonics of the virginia north carolina blue ridge evolution of a late proterozoic early paleozoic hinge zone late proterozoic 690 570 ma through ordovician rocks of the virginia north carolina blue ridge and valley and ridge record the evolution of an eastward facing passive margin and its subsequent deformation during continent arc collision taconic orogeny comparison of blue ridge stratigraphy with modern rifts and passive margins suggests that late proterozoic rifting involved substantial crustal attenuation in the eastern blue ridge the axial zone of the blue ridge from central virginia southward is occupied by a major fault system hayesville fries rock fish valley fault contrasts between rocks deposited east and west of this fault suggest that it is a reactivated hinge zone separating highly attenuated continental crust to the east from continental crust of more normal thickness to the west during rifting normal faulting and rapid subsidence of attenuating crust in the eastern blue ridge produced rift basins in which deep water clastic and volcanic rocks accumulated lynchburg group ashe formation landward of the hinge zone in the western blue ridge mainly terrestrial to shallow water clastic and volcanic rocks were deposited in a series of subaerial rift basins swift run catoctin grandfather mountain mount rogers formations the hinge zone not only controlled depositional patterns throughout the rift and passive margin history but it was also reactivated during the taconic collision when attenuated crust and its cover were thrust westward over the shelf edge turbidite dominated rift sequences of the eastern blue ridge are unlike typical rift deposits which are characterized by predominantly subaerial and shallow water sedimentation deep water rifts may be common on attenuated crust as in the bay of biscay however they are poorly known from the stratigraphic record because of their susceptibility to destruction during orogeny

mapping mineral prospectivity through big data analytics and a deep learning algorithm abstract identification of anomalies related to mineralization and integration of multi source geoscience data are essential for mapping mineral prospectivity in this study we applied big data analytics and a deep learning algorithm to process geoscience data to identify and integrate anomalies related to skarn type iron mineralization in the southwestern fujian metallogenic zone of china based on the geological setting and environment for the formation of skarn type iron mineralization 42 relevant variables including two geological one geophysical and 39 geochemical variables were analyzed and integrated for detecting anomalies related to mineralization using a deep autoencoder network the results indicate that the mapped prospectivity areas have a strong spatial relationship with the locations of known mineralization and demonstrate that big data analytics supported by deep learning methods is a potential technique to be considered for use in mineral prospectivity mapping

singularity analysis of global zircon u pb age series and implication of continental crust evolution abstract recently compiled global databases of igneous and detrital zircon u pb ages have been integrated with other types of isotope data e g neodymium hafnium and oxygen to characterize the episodic growth of the continental crust and the development of supercontinents however to what extent do the age peaks reflect the rate of continent crust growth or the differential preservation due to supercontinent settings is a long standing question instead of analyzing amplitudes and periodicity of the age series here the analysis focuses on shapes of the individual age peaks described by a power law model for measuring the scale invariant fractality and singularity of time series records the results indicate that zircon age distributions around peaks follow power law distribution regardless of the bin size used to measure the age distribution based on the commonly accepted mechanisms phase transition self organized criticality and multiplicative cascade processes for generation of power law distributions one can relate the nonlinearity of the age peaks to short spurts of accelerated magmatic activities due to avalanches superplumes slab breakoff etc occurred during episodic convection of the mantle the exponents of the power law age distributions estimated from the age peaks can be used as an index to quantify the intensity of a singularity the values of exponents calculated at all major age peaks from five global databases exhibit an episodic nature with a mean duration of approximately 600 800 myr both intensity of the zircon episodes and their duration for the interval from 3 ga to 0 5 ga depict a descending trend which may signify mantle cooling

the lower changjiang yangzi yangtze river metallogenic belt east central china intrusion and wall rock hosted cu fe au mo zn pb ag deposits abstract the lower valley of changjiang from wuhan of the hubei province in the west to zhenjiang of the jiangsu province in the east contains more than 200 polymetallic cu fe au mo zn pb ag deposits and is one of the most important metallogenic belts in china this metallogenic belt situated at the northern margin of the yangzi craton and bordered by the dabieshan ultrahigh pressure metamorphic belt to the north consists mainly of cambrian triassic marine clastic sedimentary rocks and carbonate and evaporite rocks which overlay a precambrian basement and are intruded by yanshanian 205 to 64 ma granitoid intrusions and subvolcanic complexes repeated tectonism from late proterozoic to triassic resulted in extensively developed networks of faults and folds involving the cambrian triassic sedimentary strata and the precambrian basement the yanshanian granitoid intrusions and subvolcanic complexes in the lower changjiang metallogenic belt are characterized by whole rock 18 o of 8 to 10 initial 87 sr 86 sr of 0 704 to 0 708 and ndt from 10 to 17 and have been interpreted to have originated from mixing between juvenile mantle and old crustal materials also the yanshanian granitoids exhibit eastward younging and increase in alkalinity i e from older calc alkaline in the west to younger subalkaline alkaline in the east which are related to oblique collision between the yangzi and sino korean cratons and tectonic evolution from early compressional to late extensional or rifting regimes most polymetallic deposits in the lower changjiang metallogenic belt are clustered in seven districts where the yanshanian magmatism is particularly extensive from west to east edong jiurui anqing guichi luzhong tongling ningwu and ningzhen mineralization is characterized by the occurrence of three distinct types of orebodies in individual deposits orebodies in yanshanian granitoid intrusions skarn orebodies at the contact zones between the yanshanian intrusions and late paleozoic early mesozoic sedimentary rocks and stratabound massive sulfide orebodies in the late paleozoic early mesozoic sedimentary strata the most important host sedimentary strata are the middle carboniferous huanglong formation lower permian and lower middle triassic carbonate and evaporite rocks the intrusion hosted and skarn orebodies exhibit well developed zonation in alteration assemblages metal contents and isotopic compositions within individual deposits and apparently formed from hydrothermal activities related to the yanshanian magmatism the stratabound massive sulfide orebodies in the late paleozoic early mesozoic sedimentary strata have long been suggested to have formed from sedimentary or volcano sedimentary exhalative processes in shallow marine environments however extensive research over the last 40 years failed to produce unequivocal evidence for syngenetic mineralization on the basis of geological relationships and isotope geochemical characteristics we propose a carbonate hosted replacement deposit model for the genesis of these stratabound massive sulfide orebodies and associated skarn orebodies this model suggests that epigenetic mineralization resulted from interactions between magmatic fluids evolved from the yanshanian intrusions with carbonate and evaporite wall rocks mineralization was an integral but distal part of the larger hydrothermal systems that formed the proximal skarn orebodies at the contact zones and the intrusion hosted orebodies the stratabound massive sulfide deposits of the lower changjiang metallogenic belt share many features with the well studied high temperature carbonate hosted replacement deposits of northern mexico and western united states particularly with respect to association with small shallow granitoid complexes structural and stratigraphic controls on mineralization alteration assemblages geometry of orebodies metal association metal zonation and isotopic systematics

mineral zoning and gold occurrence in the fortuna skarn mine nambija district ecuador the fortuna oxidized gold skarn deposit is located in the northern part of the nambija gold district southern ecuador it has been subdivided into four mineralized sites covering a distance of 1 km which are named from north to south cuerpo 3 mine 1 mine 2 and southern sector massive skarn bodies occur in k na metasomatized volcanic and volcaniclastic rocks of the triassic piuntza unit they appear to result from selective replacement of volcaniclastic rocks very minor presence of bioclast relicts suggests the presence of subordinate limestone endoskarn type alteration with development of na rich plagioclase k feldspar epidote actinolite anhedral pyroxene and titanite affects a quartz diorite porphyritic intrusion which crops out below the skarn bodies in mine 2 and the southern sector endoskarn alteration in the intrusion grades into a k feldspar biotite magnetite assemblage k alteration suggesting that skarn formation is directly related to the quartz diorite porphyritic intrusion the latter being probably emplaced between 141 and 146 ma the massive skarn bodies were subdivided into a dominant brown garnet skarn a distal green pyroxene epidote skarn and two quartz rich varieties a blue green garnet skarn and light green pyroxene garnet skarn which occur as patches and small bodies within the former skarn types the proximal massive brown garnet skarn zone is centered on two 060 trending faults in mine 2 where the highest gold grades 5 10 g t were observed it grades into a distal green pyroxene epidote skarn zone to the north cuerpo 3 granditic garnet shows iron enrichment from the proximal to the distal zone diopsidic pyroxene exhibits iron and manganese enrichment from proximal to distal zones the retrograde stage is weakly developed and consists mainly of mineral phases filling centimeter wide veins vugs and interstices between garnet and pyroxene grains the main filling mineral is quartz followed by k feldspar epidote calcite and chlorite with minor sericite apatite titanite hematite pyrite chalcopyrite and gold metal and sulfur contents are low at fortuna and the highest gold grades coincide with high hematite abundance which suggests that retrograde stage and gold deposition took place under oxidizing conditions fluid inclusions from pyroxene indicate precipitation from high temperature high to moderate salinity fluids 400 to 460 c and 54 to 13 wt eq nacl which result probably from boiling of a moderately saline 8 wt eq nacl magmatic fluid later cooler 180 to 475 c and moderate to low saline fluids 1 to 20 wt eq nacl were trapped in garnet epidote and quartz and are interpreted to be responsible for gold deposition chlorite analysis indicates temperature of formation between 300 and 340 c in accordance with fluid inclusion data it appears thus that gold was transported as chloride complexes under oxidizing conditions and was deposited at temperatures around 300 c when transport of chloride complexes as gold carriers is not efficient

p t conditions during skarn formation in the ocna de fier ore district romania p t conditions during skarn formation in the 75 5 ma old ocna de fier dognecea sw romania ore district are assessed in this work using a combination of petrogenetic grids berman s tweequ programme and several independent geothermobarometers these were applied both to hornfelses surrounding the skarn and to the granodiorite which caused the skarn and contact metamorphism the results are consistent and point to a peak metamorphic temperature of 700 50 c decreasing away from the contact and to a pressure of 2 8 1 kbar equivalent to 10 km depth in the region these results quantify the qualitative idea that skarn mineralisation normally forms in a high t low p contact metamorphic environment

identifying gravity anomalies caused by granitic intrusions in nanling mineral district china a multifractal perspective several power law relationships of geophysical potential fields have been discussed recently with renewed interests including field value distance f r and power spectrum wavenumber p models the singularity mapping technique based on the density concentration area c a power law model is applied to act as a highpass filter for extracting gravity and magnetic anomalies regardless of the background value and to detect the edges of gravity or magnetic sources with the advantage of scale invariance this is demonstrated on a synthetic example and a case study from the nanling mineral district southern china compared with the analytic signal amplitude and total horizontal gradient methods the singularity mapping technique provides more distinct and less noisy boundaries of granites than traditional methods additionally it is efficient for enhancing and outlining weak anomalies caused by concealed granitic intrusions indicating that the singularity method based on multifractal analysis is a potential tool to process gravity and magnetic data

exploration information systems a proposal for the future use of gis in mineral exploration targeting abstract the advent of modern data collection and storage technologies has brought about a huge increase in data volumes with both traditional and machine learning tools struggling to effectively handle manage and analyse the very large data quantities that are now available the mineral exploration industry is by no means immune to this big data issue exploration decision making has become much more complex in the wake of big data in particular with respect to questions about how to best manage and use the data to obtain information generate knowledge and gain insight one of the ways in which the mineral exploration industry works with big data is by using a geographic information system gis for example gis platforms are often used for integration interrogation and interpretation of diverse geoscience and mineral exploration data with the goal of refining and prioritising known and identifying new targets here we i briefly discuss the importance of carefully translating conceptual ore deposit models into effective exploration targeting maps ii propose and describe what we term exploration information systems eis a new idea for an information system designed to better integrate the conceptual mineral deposit model i e the critical and constituent processes of the targeted mineral system with data available to support exploration targeting and iii discuss how best to categorise mineral systems in an eis as scale dependent subsystems to form mineral deposits our vision for the future use of eis in exploration targeting is one whereby the mappable ingredients of a targeted mineral system are translated and combined into a set of weighted evidence or proxy maps automatically resulting in an auto generated mineral prospectivity map and a series of ranked exploration targets we do not envisage the eis replacing human input and ingenuity rather we envisage the eis as an additional tool in the exploration toolbox and as an intelligence amplifying system in which humans are making use of machines to achieve the best possible results

late proterozoic extensional deformation of blue ridge basement in virginia supporting evidence from simple field relations field relations in northern virginia support the interpretation that a significant portion of the finite strain in the basement terrane of the blue ridge anticlinorium is a result of continental rifting in the late proterozoic widespread greenschist facies disjunctive foliation overprints high temperature grenvillian textures in basement orthogneisses an identical foliation occurs in randomly oriented basement derived boulders within late proterozoic rift facies conglomerates of the cover sequence the disjunctive foliation in the basement is also truncated at the exposed contact with cover rocks and a greenschist facies phyllonite zone in the basement is truncated at a late proterozoic syn rift fault these greenschist facies tectonic fabrics which are clearly pre paleozoic in age are similar to fabrics in extensional shear zones in basement rocks that have been shown by others to predate paleozoic compressional structures

fractals in petrology abstract a fractal power law distribution is the only statistical distribution applicable to a scale invariant process one of the major problems in petrology is the distribution of trace elements in the earth s crust extreme values of this distribution result in ore deposits there is accumulating observational evidence that tonnage grade statistics of ore deposits are often fractal power law rayleigh distillation and chromatographic models can explain power law fractal distributions for the extreme values of trace element concentrations an alternative fractal approach to problems in petrology is to use self affine fractals the standard approach is to take a fourier transform of a continuous signal an example would be the concentration of a mineral along a linear track if the fourier coefficients scale as a power law of the wavelength the distribution is a self affine fractal many well logs give this result multifractal analyses can also be applied to problems in petrology

entropy theory integrated information model for the assessment of geothermal potential a case study of tengchong county southwest china geothermal energy remains a largely undeveloped natural resource because of the high risk associated with its development an accurate prediction model for easy identification of potential regions can help to lower the risk and cost associated with development in this study geothermal potential regions were identified through the relationship between geothermal emergencies and their controlling factors in tengchong county china publicly available databases for this analysis including epicenters active faults bouguer gravity landsat7 enhanced thematic mapper plus images the magnetic data and digital elevation model data were extracted as the b value map distance to faults map distance to main grabens map land surface temperature map magnetic anomaly map and distance to rivers map respectively based on the platforms within geographic information system an entropy theory integrated information model was established to evaluate the geothermal potential sites within the region moreover factor analysis method was applied to test the conditional independence between the map pairs before modeling application the results of the weighted information model show that the model shows perfect performance in discovering potential geothermal regions in the final maps undeveloped or unexploited geothermal regions can be observed along the mingguang river and nu river undeniably these models will help to find undiscovered geothermal regions with limited geological information publically available

a comparison study of the c a and s a models with singularity analysis to identify geochemical anomalies in covered areas abstract fractal multifractal modeling of geochemical data is an interesting topic in the field of applied geochemistry identification of weak anomalies for mineral exploration in covered areas is one of the most challenging tasks for utilization of geochemical data in this study three fractal models consisting of the concentration area c a spectrum area s a and singularity index models were applied to identify geochemical anomalies in the covered area located in the chaobuleng fe polymetallic district inner mongolia china the results show that 1 the grassland cover weakens the concentrations of geochemical elements 2 the c a model has a limitation to identify weak anomalies in covered areas 3 the s a model is a powerful tool to decompose mixed geochemical patterns into a geochemical anomaly map and a varied geochemical background map but suffers edge effects in an irregular shaped study area and 4 the singularity index is a useful tool to identify weak geochemical anomalies

orebody vertical structure and implications for ore forming processes in the xinxu bauxite deposit western guangxi china abstract the xinxu bauxite orebodies which are contained in quaternary depressions overlying strata of permian to devonian age were formed through the break up oxidation and re sedimentation of a pre existing permian bauxite horizon with progressive karsitification the underlying strata of the quaternary orebodies were eroded out downwards in sequence gradually transiting from permian to devonian thus an older underlying stratum generally infers a higher degree of weathering a total of 47 exploration wells sampled each meter were chosen from several orebodies to evaluate the vertical distribution of four major components al 2 o 3 fe 2 o 3 sio 2 and loss on ignition in the ores the vertical evenness is quantified via a box gliding multifractal model the small width of the multifractal spectrum suggests that the vertical ore quality is even overall indicating an intertwining break up and mixing up processes during evolution of the quaternary orebody although the four components show complex spatial distributions topographic elevation displays a positive relationship with the mean fe 2 o 3 content and a negative correlation with the vertical unevenness of al 2 o 3 and fe 2 o 3 in the wells this is taken to reflect the more uniform oxidizing environment in the higher depressions which facilitates a homogeneous and greater increase of fe 2 o 3 content throughout the orebody in contrast the redox conditions in lower depressions are less oxidizing and varied in space inducing great variation in degree of fe 2 o 3 increase in the ores this study also demonstrates that in the xinxu deposit the ore forming redox environment has more impact on the ore quality than the degree of weathering as the contents show irregular vertical changes in the lower depressions it follows that it is the ancient redox environment rather than the modern conditions which affect the orebody vertical structure this clarifies the fact that the vertical structure of the orebody is jointly constrained by the physical melange accumulation of ores and the differences between the ancient redox environments in the higher and lower locations these factors should be the primary factors affecting the vertical structure of karst bauxite deposits

prospectivity analysis of orogenic gold deposits in saqez sardasht goldfield zagros orogen iran abstract diverse deposit types or mineral systems form by diverse geological processes so translation of knowledge about the controls of mineralization acquired from the 4d geological modeling into 2d spatial predictor maps is a major challenge for prospectivity analysis in this regard mathematical functions have been used to model the conceptual or perceived spatial relationships between geological variables and targeted type or system of mineralization in this paper due to the different models of spatial relationships between predictors and mineral deposits we investigated the performance of different fuzzification functions to quantify the relationships we demonstrated that various types of relationships between exploration features and a mineralization type sought could be quantified using different fuzzification functions for prospectivity analysis we illustrated the process of the prospectivity analysis by using a data set of orogenic gold deposits in saqez sardasht goldfield iran prospectivity modeling of orogenic gold mineralization in the study area showed that the ne sw trending targets have priority for further prospecting of the deposits

a multifractal analysis of mineralization characteristics of the dayingezhuang disseminated veinlet gold deposit in the jiaodong gold province of china abstract the gold concentration distributions along drifts in the dayingezhuang fault controlled disseminated veinlet gold deposit in the jiaodong gold province eastern china has been analyzed using a multifractal technique with the aim of better understanding the ore forming processes some intensely mineralized areas show small gold singularities representing compact concentration distributions which is resulted from intense stress release and development of abundant microfractures with various sizes several intensely and moderately mineralized areas are characterized by isolated distributions of lower concentrations suggesting that only relatively large microfractures locally develop resulted from less intense stress release some barely and moderately mineralized areas show isolated distributions of higher concentrations due to occurrences of only a few fractures or large microfracture most barely mineralized areas are characterized by dense concentrations distributions because the widespread development of relatively small microfractures caused by weak stress release thus making the areas unsuitable for gold deposition these characteristics reflect that variable development of the structures is responsible for different gold mineralization within the deposit the ratios between the singularity a q and its fractal dimension f a q for the different drifts vary similarly as q 0 8 or q 0 8 thus from the multifractal viewpoint it is suggested that gold enrichment processes are consistent in both mineralized and barely mineralized areas despite their differing mineral intensities

effective use and interpretation of lithogeochemical data in regional mineral exploration programs application of geographic information systems gis technology abstract a geographic information system gis in concert with statistical and geostatistical software has been used to compile manipulate analyze and visualize a large lithogeochemical dataset collected from the archean age swayze greenstone belt sgb located in northern ontario canada altered samples from this database have been identified using a variety of univariate and multivariate statistical and visualization techniques alteration maps are produced for each method and compared to known gold mineralization using the weights of evidence wofe technique major oxide data are interpolated using different sample groups all altered unaltered normalized samples and anomalous concentrations are separated from background using breakpoints on probability plots of the data as well as statistics generated from wofe analysis these maps are also evaluated using wofe analysis with respect to locations of known gold prospects the atypical normative mineral method is more sensitive for identifying alteration in felsic rocks felsic volcanic rocks granitoids whereas the volatile method is more sensitive for detecting alteration in mafic volcanic rocks and sedimentary rocks altered samples are characterized by higher sio2 k2o and mno concentrations and lower mgo and tio2 concentrations areas within the greenstone belt characterized by high concentrations of cao fe k2o and al2o3 were found to the best predictors of the known gold prospects anomalously high concentrations of these oxides reflect carbonatization fe carbonate alteration and potassic alteration trends and indicate that these alteration styles are spatially related to gold mineralization the wofe method is a useful technique with which to evaluate the geochemical maps produced in this paper the wofe technique is useful not only for comparing geochemical anomalies to the location of known gold prospects but also for providing a quantitative measure of association between anomalies and gold prospects furthermore the gold potential maps generated using wofe not only highlight or predict known areas of gold mineralization but also identify high potential areas where no known mineralization occurs a number of areas within the sgb have been identified as having high gold potential on many of the geochemical maps produced in this paper many of these areas coincide with areas of known gold mineralization however others are enigmatic and await follow up exploration