a bound on the rheology of continental lithosphere using very long baseline interferometry the velocity of south china with respect to eurasia very long baseline interferometric vlbi measurements using the antenna near shanghai china between 1987 and 1994 show that this site moves at 8 0 5 mm yr 1 in the direction n116 5 e 4 1 with respect to vlbi sites in europe on the eurasia plate independent measurements of the site at shanghai with respect to sites on nearly all major plates eurasia north america pacific australia and africa determine this velocity south china translates east southeast relative to eurasia more slowly than 20 of india s roughly 50 mm yr convergence rate with eurasia and hence accommodates only a small fraction of india s penetration into eurasia apparently crustal thickening absorbs most of india s convergence the relatively low speed of south china supports treatments of continental lithosphere as a thin viscous sheet whose strength is governed primarily by power law creep in the upper mantle and not by friction in the crust

holocene tsunamis in the southwestern bering sea russian far east and their tectonic implications the bering sea coast of kamchatka overlies a boundary between the proposed okhotsk and bering blocks or micro plates of the north american plate in the russian far east a history of tsunamis along this coast for the past 4000 yr indicates that the zone north of the kuril kamchatka subduction zone produces tsunamigenic earthquakes every few centuries such a record is consistent with convergence of the proposed okhotsk and bering blocks along the bering sea coast of kamchatka a tsunami deposit from the 1969 m w 7 7 ozernoi earthquake helps us interpret older tsunami deposits newly studied tephra layers from shiveluch volcano as well as previously established marker tephra layers in northern kamchatka provide age control for historic and prehistoric tsunami deposits based on 50 measured sections along 14 shoreline profiles tsunami deposit frequencies in the southwestern bering sea are about five per thousand years for tsunamis generated north of the kuril kamchatka trench

receiver operating characteristics roc as validation tool for prospectivity models a magmatic ni cu case study from the central lapland greenstone belt northern finland abstract a prospectivity model for magmatic ni cu deposits was created by integrating spatially referenced geophysical and geochemical datasets based on a simple and practical exploration model the study area is the central lapland greenstone belt northern fennoscandian shield finland magmatic nickel deposits are related to rock types that are typically characterized by local magnetic and gravity anomalies these deposit types can also be a source of nickel copper and cobalt anomalies in the overlying glacial till cover this straightforward exploration criterion was translated into a fuzzy logic prospectivity model the model validation is an essential step in justifying the validity of the prospectivity model this was accomplished by using receiver operating characteristics roc technique we used the known ni cu occurrences and deposits as true positive cases and other deposit type locations or random points as true negative cases in the validation process it appears that the roc technique provides a robust model validation and optimization technique providing that suitable validation data exists

kinematic model of active deformation in central asia the velocity field of present day deformation in central asia is modelled using a set of four rotating blocks siberia tarim tibet india on a spherical earth a best fit is inverted on the basis of estimated shortening rates across the main thrust zones himalayas tien shan and measured slip rates along the principal strike slip faults altyn tagh and karakorum separating those blocks the fit to the data implies that nearly all the present convergence between india and asia can be accounted for by slip partitioning on these four zones with as much as 50 absorbed by northeastwards extrusion of tibet this suggests that localised deformation governs the present mechanical behaviour of the central asian lithosphere

low vp vs ratios in the crust and upper mantle beneath the sea of okhotsk inferred from teleseismic pmp smp and sms underside reflections from the moho 1 teleseismic ground motion recordings of deep earthquakes often contain clear seismic wave reflections from the free surface above the source pp sp ss with isolated precursors pmp smp and sms produced by underside reflections from the moho the crust mantle boundary below the free surface reflection points the waveforms of the depth phases and their precursors are readily modeled providing constraints for steep angles of incidence on integrated two way crustal travel times and moho shear and compressional impedance contrasts above deep earthquake source regions we model surface reflection waveforms in stacks of three component long period wwssn and digital broadband seismograms for signals traversing the crust and upper mantle beneath the sea of okhotsk which overlies deep earthquakes in the subducted kurile slab the crust beneath most of the sea of okhotsk is 19 25 km thick indicating a submerged continental margin with minor crustal thinning toward the kuril back arc basin where thin oceanic crust is found modeling pmp and sms phases that sample the same subregion provides tight constraints on the vp vs ratio in the crust and uppermost mantle assuming common density structure and consistent crustal thickness for p and s waves the absolute velocities are not constrained by the data we find unusually low vp vs ratios in the range 1 6 1 7 for the uppermost mantle under the sea of okhotsk and comparably low average vp vs ratios for the crust in several regions the presence of fluids and extensive silica enrichment possibly involving low temperature veining are viable explanations for the anomalous vp vs ratios this may represent an important process of continentalization taking place landward from the volcanic arc in subduction zones

a review of the intracontinental porphyry deposits in the middle lower yangtze river valley metallogenic belt eastern china abstract the middle lower yangtze river valley metallogenic belt mlyb is one of the most important metallogenic belts in eastern china and contains many important porphyry deposits these deposits include the tongshankou cu mo jiguanzui cu au chengmengshan cu mo wushan cu mo fengshandong cu au dingjiashan cu yangjishan au shaxi cu au dongguashan cu au shujiadian cu and anjishan cu deposits etc in this review we summarize the geological characteristics including the stratigraphy structure ore bearing porphyry types vein characteristics and wall rock alteration metallogenic ages and petro geochemistry of representative porphyry deposits in the mlyb we conclude that porphyritic magmatism and metallogeny have occurred in three stages the early ca 149 135 ma and late ca 123 105 ma stages comprise mainly porphyry skarn mineralization whereas the middle ca 133 125 ma stage comprises porphyry mineralization ore bearing porphyries in the mlyb are the high k calc alkaline to calc alkaline series with the majority possess adakitic geochemical signature the ore bearing porphyries with adakitic signature may have originated from magma mixing produced by the delamination of enriched lithospheric mantle and partial melting of the thickened lower crust the enriched mantle derived mafic melts component are very important for generating fertile magma and the 34s and 18o values suggest that ore forming materials were magma derived compared with porphyry deposits in typical magmatic arc settings porphyry deposits in the mlyb do not contain advanced argillic lithocaps or high to intermediate sulfidation systems and the magmatic and ore forming material sources are also very different

weights of evidence and logistic regression modeling of magmatic nickel sulfide prospectivity in the yilgarn craton western australia abstract bayesian weight of evidence and logistic regression models are implemented in a gis environment for regional scale prospectivity modeling of greenstone belts in the yilgarn craton western australia for magmatic nickel sulfide deposits the input variables for the models consisted of derivative gis layers that were used as proxies for mappable exploration criteria for magmatic nickel sulfide deposits in the yilgarn about 70 of the 165 known deposits of the craton were used to train the models the remaining 30 was used to validate the models and therefore had to be treated as if they had not been discovered the weights of evidence and logistic regression models respectively classify 71 4 and 81 6 validation deposits in prospective zones that occupy about 9 of the total area occupied by the greenstone belts in the craton the superior performance of the logistic regression model is attributed to its capability to accommodate conditional dependencies amongst the input predictor maps and provide less biased estimates of prospectivity

mineral deposit model for porphyry skarn polymetallic copper deposits in tongling ore dense district of middle lower yangtze valley metallogenic belt according to field investigations of major ore deposits along the middle lower yangtze valley metallogenic belt and a detailed study of the data available the authors put forward a mineral deposit model based on the tongling ore district the largest ore cluster in the belt the porphyry skarn cu au mo ore bodies developed around the roof pendants of the high potash calc alkaline granitoids have experienced strong fractionation since there are extensively distributed carboniferous permian carbonates both calcic and magnisian skarn deposits have most important economic significance as components of the porphyry skarn system the skarn and vein like gold deposits and veinlike pb zn ag deposits are distributed outward gradually from the intrusion and the porphyry skarn cu au mo ore deposits because the middle lower yangtze valley belt was a foreland basin during the collision between the south china massif and the north china craton and subsequently a depression belt during the post collision with a lot of decollement and detachment faults especially along the discontinuity boundary which occupied a large space the large ore bodies must have been formed along the large space such as the major ore body in the xinqiao s cu au polymetallic mine the strong retrograde alteration consisting of actinolite tremolite chlorite epidote or serpentine mg chlorite talc tremolite with typical wrigglite and laminated structures along either fractures or discordant boundary replaced the skarn at the contact with the granitoid intrusion there are also a lot of manto or stratabound skarn ore bodies replacing some carbonate layers of different ages this paper also indicates the correct utilization of the model together with some types of geochemical and geophysical technologies for further prospecting in similar tectonic settings

late eocene granites in the central sakhalin island russian far east and its implication for evolution of the sakhalin hokkaido orogenic belt abstract the sakhalin hokkaido orogenic belt along the western margin of the okhotsk sea is an important early cenozoic accretionary orogen related to subduction of the paleo pacific oceanic plate in order to study the eocene evolution of this accretionary orogen and related magmatism we carried out zircon u pb dating whole rock elemental and sr nd isotopic analyses on the langeri and val za granitic plutons that intruded the east sakhalin accretionary complex in the central sakhalin island zircon u pb dating results revealed that the langeri and val za plutons were emplaced in the late eocene at 38 36 ma whole rock elemental data indicate that granitoids are mainly peraluminous s type with subordinate i type granites and all granitic samples show arc like geochemical affinity whole rock sr nd isotopic results show consistent low initial 87sr 86sr ratios 0 7042 to 0 7049 positive end t values 1 7 to 3 1 and young nd two stage model ages 611 to 717 ma elemental and isotopic data reveal that granitic rocks of the langeri and val za plutons were generated from remelting of metasediments and amphibolites in the accretionary complex from comprehensive analyses of regional tectonics we concluded that the late eocene granitic rocks were generated in a syn collisional tectonic setting marking the timing for formation of the sakhalin hokkaido orogenic belt the middle late eocene welding of the okhotsk sea plate and the eurasia plate is the most plausible mechanism that caused crustal thickening beneath the sakhalin island and anatexis of metasediments and oceanic crustal materials in the lower crust might be responsible for the formation of late eocene granitic rocks considering the eocene tectonic events in ne asia late paleocene to early eocene subduction of the kula pacific ridge beneath the hokkaido island and eocene initial rift of pull apart basins along strike slip fault system in the hokkaido and sakhalin islands may also contribute to the emplacement of eocene magmatism in the sakhalin hokkaido orogenic belt

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

newly imaged shape of the deep seismic zone within the subducting pacific plate beneath the hokkaido corner japan kurile arc arc junction 1 the geometry of the deep seismic zone associated with the subducting pacific plate beneath the north american plate in the hokkaido corner japan kurile arc arc junction has been investigated based on the hypocenters accurately relocated by a dense local seismographic network with three dimensional p and s wave velocity structures the model suggests that the lateral changes in the dip of the subduction zone are more rapid than previously believed we found that the deep seismic zone in the pacific plate dips at 20 to 30 on the side of the japan arc the dip angle increased in a narrow region around 143 144 e by 10 to 20 and the dip was 40 to 50 on the side of the kurile arc in the transitional zone around 143 144 e an unusual distribution of microearthquakes has been discovered within the pacific plate which was located on a near vertical plane with an area of 50 100 km2 with strike that was perpendicular to the kurile trench axis this feature was named the tokachi oki slab cracking zone we suggest that this is a slab cracking zone torn by the extensional stress due to the rapid lateral changes in the dip of the subduction zone the slab cracking zone may possibly grow into the large disruption or tear of the slab in the future

a new method for imaging seismic quiescence and its application to the m w 8 3 kurile islands earthquake on 15 november 2006 in the present paper a new method referred to as the poisson probability map pmap method is presented for identifying and visualizing seismic quiescence with the pmap the p value is defined as the probability that consecutive earthquakes occur according to a homogeneous poisson process the smaller the p value the less frequently the longer time interval is observed i e the more significant the seismic quiescence the pmap method was applied to the sequence which preceded the kurile islands earthquake that occurred on 15 november 2006 mw 8 3 and the centroid 154 33 e 46 71 n the seismic quiescence is identified by a small p value of 9 0 10 5 that was found to start in 1990 1 which lasted for 15 4 years and ended in 2005 5 within a circular area centered at 153 8 e 47 1 n and with a radius of 26 km this seismic quiescence has not previously been recognized using any other method

translating the mineral systems approach into an effective exploration targeting system abstract holistic mineral systems approaches are being increasingly adopted in the study of ore deposits but application in industry has been suboptimal because of the lack of a conceptual framework to help translate the mineral system understanding to practical application a four step process is proposed for linking the conceptual mineral system with data available to support exploration targeting these steps include translation from 1 critical processes of the mineral system to 2 constituent processes of the mineral system to 3 targeting elements reflected in geology and 4 targeting criteria used to detect the targeting elements directly or by proxy this translation process is illustrated using examples from komatiite hosted ni cu pge and orogenic au mineral systems ranking of targets must be at the critical process level rather than the current practice of mixing processes elements and proxies the significance of targeting elements and their mappable criteria changes as a function of the scale at which the critical processes operate and the availability of relevant geoscience datasets this scale dependence is rarely recognised in current practice sources of uncertainty when translating the mineral system understanding into an effective exploration targeting system include 1 resolution of a mappable criterion in a dataset 2 how well the targeting criterion reflects the targeting element 3 how well the targeting element reflects the critical process and 4 whether the process being mapped is critical for the genesis of a mineral deposit the first three sources of uncertainty collectively are termed the representativeness of the targeting criteria i e how representative is a mappable criterion of the constituent process for which it is a proxy the last source of uncertainty reflects our lack of understanding of the processes that control mineralisation and highlights areas for further research

petrogenesis and mineralization of the fenghuangshan skarn cu au deposit tongling ore cluster field lower yangtze metallogenic belt article the fenghuangshan copper gold deposit located in the tongling ore cluster field along the lower yangtze metallogenicbelt lyrb ineasternchina mainlyconsistofskarnoreshostedingranodiorite u pb dating of mag matic zircons from fenghuangshan granodiorite yields a weighted mean 206 pb 238 u age of 143 1 1 6 ma five molybdenite samples collected in the fenghuangshan deposit yield a re osisochronage of 141 7 0 8 ma dem onstrating that the ore formation event is coeval with the fenghuangshan granodiorite intrusion the magmatic zircon hf t values vary from 12 0 to 28 3 corresponding two stage hf model ages between 1 6 ga to 2 4 ga geochemical and isotopic signatures suggest that the fenghuangshan granodiorite resembles adakite which was derived from partial melting of the subducted oceanic crust towards lyrb during the early cretaceous the occurrence of inherited zircons shows the intrusive granodiorite was assimilated by old crustal materials dur ing its emplacement the biotite thermobarometry zircon ce iv ce iii ratios and eu anomalies coincidently demonstrate that the magma source of granodiorite was under high to moderate oxidized condition conducive to cu au mineralization the sulfide ores in fenghuangshan deposit are enriched in pd and pt which could also be a consequence of the high oxidized magma source the high re abundance in molybdenite and platinum group element pge contents of sulfide ores suggest that the ore forming materials are characterized by mixed sources from the mantle and crust and were slightly affected by hydrothermal alteration

data driven predictive mapping of gold prospectivity baguio district philippines application of random forests algorithm the random forests rf algorithm has recently become a fledgling method for data driven predictive mapping of mineral prospectivity and so it is instructive to further study its efficacy in this particular field this study carried out using baguio gold district philippines examines a the sensitivity of the rf algorithm to different sets of deposit and non deposit locations as training data and b the performance of rf modeling compared to established methods for data driven predictive mapping of mineral prospectivity we found that rf modeling with different training sets of deposit non deposit locations is stable and reproducible and it accurately captures the spatial relationships between the predictor variables and the training deposit non deposit locations for data driven predictive mapping of epithermal au prospectivity in the baguio district we found that a the success rates of rf modeling are superior to those of weights of evidence evidential belief and logistic regression modeling and b the prediction rate of rf modeling is superior to that of weights of evidence modeling but approximately equal to those of evidential belief and logistic regression modeling therefore the rf algorithm is potentially much more useful than existing methods that are currently used for data driven predictive mapping of mineral prospectivity however further testing of the method in other areas is needed to fully explore its usefulness in data driven predictive mapping of mineral prospectivity

ore geology and fluid inclusions of the hucunnan deposit tongling eastern china implications for the separation of copper and molybdenum in skarn deposits abstract the hucunnan ore deposit is a representative skarn cu mo deposit in the tongling district an important ore district of the renowned middle lower yangtze river metallogenic belt of china the deposit shows distinct zonation of metals with cu mineralization distributed mainly in the exoskarn zone at shallow depths and mo mineralization occurring chiefly in the endoskarn zone located at deeper depths field evidence and petrographic observations indicate that the ore forming processes can be divided into the skarn quartz molybdenite quartz chalcopyrite and carbonate stages five types of fluid inclusions fis are present in the deposit solid bearing type 1 liquid rich type 2 vapor rich type 3 pure vapor type 4 and co 2 bearing type 5 the skarn stage contains mainly type 1 and 2 but also minor type 3 and 4 fis the fis display homogenization temperatures of 434 570 c and salinities of 2 07 66 0 wt nacl equiv the existence of hematite daughter minerals in the type 1 inclusions together with the presence of magnetite in skarn implies that the skarn stage fluid was oxidizing the skarnization of the granodiorite porphyry is commonly accompanied by potassic alteration suggesting that the fluids were rich in alkali similar to the skarn stage the quartz molybdenite stage contains type 1 and 2 and minor type 3 and 4 fis which yield homogenization temperatures of 280 458 c and salinities of 1 40 54 2 wt nacl equiv the presence of sulfide instead of hematite daughter minerals in the type 1 inclusions in quartz molybdenite veins associated with sericitization indicates that the fluids of the quartz molybdenite stage were more reducing and more acidic than the fluids in the skarn stage the decrease in oxygen fugacity and increase in acidity could have resulted from magnetite crystallization and the consumption of alkali cations and oh respectively during the skarn stage the quartz chalcopyrite stage contains all types of fis which show homogenization temperatures of 203 392 c and salinities of 1 22 46 6 wt nacl equiv observations of hematite bearing type 1 fis in quartz chalcopyrite veins containing anhydrite associated with biotitization suggest that the fluids of the quartz chalcopyrite stage were oxidizing and alkali rich probably on account of the inflow of meteoric water and boiling in an open system in the carbonate stage only type 2 fis are present these fis yield the lowest homogenization temperatures of 156 276 c and the lowest salinities of 1 05 12 3 wt nacl equiv microthermometry and h o isotope data indicate that the ore forming fluids were dominated by magmatic water in the early stages skarn and quartz molybdenite stages and that the magmatic water gradually mixed with circulating meteoric water during the late stages quartz chalcopyrite and carbonate stages the coexistence of saline and vapor rich fis as internal trails or clusters within individual crystals with similar homogenization temperatures but contrasting salinities and homogenization modes to the liquid and vapor respectively in the first three stages strongly suggests that three episodes of fluid boiling occurred in these stages as further supported by the hydrogen isotopic compositions of the fluids which are lower than those of magmatic water based on the above data we conclude that temporal changes in redox conditions acidity and temperature in the mineralizing fluids resulted in the temporal separation of cu and mo by selective sulfide precipitation in the hucunnan skarn deposit the competition among metals e g mo and cu for sulfur in magmatic fluids along with vapor brine immiscibility fluid boiling are major factors that contributed to the spatial separation of cu and mo in the deposit

developing models using gis to assess geological and economic risk an example from vms copper gold mineral exploration in oman abstract it is important to understand the financial risk involved in any business venture and recent economic conditions make this even more critical there are a variety of tools and techniques that when used with modern gis and the mineral system concept allow sophisticated economic risk analysis to be carried out including assessing uncertainty a weights of evidence model for vms copper gold mineralisation was created for the northern part of the semail ophiolite belt in oman and this has been used in conjunction with economic modelling to target prioritise and plan follow up exploration individual predictor themes of geology geochemistry and geophysical data were combined into a single predictive map for vms copper gold mineralisation the immediate benefits of carrying out this type of analysis include effective data compilation quality control of digital data understanding of critical geological factors to be used in follow up exploration ranking of prospects prioritising exploration exploration budgeting and management understanding of risk and cost reduction the prospectivity model identified 79 targets above an upper threshold in the study area nine of the targets are known historic mines or current operations 11 of the targets are known undeveloped prospects and 59 of the targets are new unexplored prospects the prospectivity model was not only used to target but also used to plan new exploration programs to collect missing data that could add the most value to developing the target economic factors were developed for each of the targets identified by the modelling to allow a more complete understanding of the exploration risk this allows targets with differing geology amounts of metal and economic factors to be compared ranked and prioritised an exploration risk value was calculated by combining the geological probability values with the economic parameters so that positive exploration risk values were considered to be potential investment targets whereas targets with negative risk values were considered being more of a gamble there are twenty six targets in the study area with positive exploration risk values which not only confirm the study areas prospectivity but also economic potential the work in oman confirms the potential for new discoveries in the region which even at low copper prices still make attractive exploration targets

does kamchatka belong to north america an extruding okhotsk block suggested by coastal neotectonics of the ozernoi peninsula kamchatka russia this paper addresses one part of an outstanding tectonic problem regarding the nature of the plate boundary between eurasia and north america in northeastern russia in this region the northwestern corner of the pacific plate interacts either simply with the north american plate or more complexly with one or more blocks independent of north america north of this corner evidence of uplift tilting and convergence contradicts the prevailing simpler model on the ozernoi peninsula similar to 150 km north of the subducting pacific plate marine terraces indicate uplift rates of 0 1 to 0 3 mm yr with faster rates to the east historic and paleoseismic records provide evidence for recurring tsunamigenic thrust earthquakes offshore of the ozernoi peninsula the most recent a mw 7 7 earthquake in 1969 a multiplate model where an eastward moving okhotsk block including most of kamchatka is converging with a clockwise rotating bering block better explains these observations than does the unbroken north american plate model

deep electrical structure and geological significance of tongling ore district abstract the tongling ore district is one of the most important cu polymetal producers in the lower yangtze river metallogenic belt of china to understand deep crust structure beneath the tongling ore district more comprehensively and objectively and to explore important scientific issues such as characteristics of lithospheric evolution the relationship between the crustal structure and metallogenesis it is necessary to study the variation of crust electrical structure in the study area for this purpose six magnetotelluric mt sounding profiles have been completed by sinoprobe 03 project based on the imaging results of the six profiles electrical conductivity structure of the crust has been analyzed the result shows that the geology beneath the profiles is characterized by layering in vertical direction and block division in horizontal direction the high resistivity features are related to the transparent zones detected at the upper crust in reflection seismic surveys the absence of reflectivity from the depths indicates a homogeneous zone which could often be related to granitic intrusions combining the regional tectonic evolution mt and other geophysical data we suggest that the high resistivity bodies crossing the tongling uplift reveals the center of magma activity and the layering in vertical direction in the lower crust reveals a normal lower crust model and propose a small scale underplating model which is different with both the partial melting of a thickened or delaminated lower continental crust model and the oceanic ridge subduction the underplating might be related to small scale lithospheric or lower crust delamination controlled by deep fault during the early cretaceous the result of this mt survey is important for constraining lithospheric evolution and metallogenesis in the lower yangtze metallogenic belt such as collision of north china craton and yangtze craton underplating models deep structure mechanisms of ne sw trending rift as well as graben basin and probable metallogenesis

a continent wide study of australia s uranium potential part i gis assisted manual prospectivity analysis abstract this paper describes the approach to and outcomes of a manual analysis i e a cognitive assessment of spatial and non spatial data of the uranium potential of 90 geological regions in australia for this analysis the 14 principal uranium deposit types recognized by the international atomic energy agency were grouped in six uranium systems models i e surficial sedimentary igneous related metamorphic metasomatic unconformity related and vein related uranium systems on the basis of similar genetic processes environments of ore formation and ingredients mappable at the regional to continent scale the newly proposed uranium systems models are structured according to the mineral systems approach and focus on the critical mineralization processes that must occur for a uranium deposit to form in a particular region our manual prospectivity analysis employed this approach to assess the probability of the critical genetic processes having occurred in each geological region in this semi quantitative probabilistic evaluation technical quality and opportunity ranking schemes were used to rank each geological region based on the probability of occurrence of and potential for high quality uranium deposits and opportunity for securing prospective ground based on this assessment the geological regions with the greatest potential for discovery of potentially recoverable uranium resources are the ashburton broken hill litchfield mcarthur money shoal murphy paterson pine creek and northeast tasmania regions i e quality ranking of 10 0 the gawler and polda regions i e 9 0 and the amadeus georgetown stuart tanami regions i e 8 1 most of these regions contain known unconformity related or sandstone hosted uranium deposits although some of them are pure conceptual plays that have received relatively little attention in terms of uranium exploration maps based on the numerical output of the prospectivity analysis helped to inform area selection decisions and detailed follow up studies and focus time and resources the template developed in this study can easily be modified to suit prospectivity analyses for other metals or a similar investigation in another country as illustrated in part ii the best possible approach to a complex continent wide prospectivity analysis is to harness the strengths of both manual and automated i e sophisticated computational techniques applied to spatial data approaches as these methodologies essentially address each other s limitations

present tectonics of the southeast of russia as seen from gps observations summary the present tectonics of northeast asia has been extensively investigated during the last 12 yr by using gps techniques nevertheless crustal velocity field of the southeast of russia near the northeastern boundaries of the hypothesized amurian microplate has not been defined yet the gps data collected between 1997 february and 2009 april at sites of the regional geodynamic network were used to estimate the recent geodynamic activity of this area the calculated gps velocities indicate almost internal between network sites and external with respect to the eurasian tectonic plate stability of the investigated region we have not found clear evidences of any notable present day tectonic activity of the central sikhote alin fault as a whole this fault is the main tectonic unit that determines the geological structure of the investigated region the obtained results speak in favour of the existence of a few separate blocks and a more sophisticated structure of the proposed amurian microplate in comparison with an indivisible plate approach

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

can the okhotsk plate be discriminated from the north american plate the plate geometry in northeast asia has been a long standing question with a major issue being whether the sea of okhotsk and northern japanese islands are better regarded as part of the north american plate or as a separate okhotsk plate this question has been difficult to resolve because earthquake slip vectors along the kuril and japan trenches are consistent with either pacific north america or pacific okhotsk plate motion to circumvent this difficulty we also use slip vectors of earthquakes along sakhalin island and the eastern margin of the japan sea and compare them to the predicted eurasia okhotsk and eurasia north america motions for a model with a separate okhotsk plate we invert 10 eurasia okhotsk and 255 pacific okhotsk slip vectors with pacific north america and eurasia north america nuvel 1 data alternatively for a model without an okhotsk plate those eurasia okhotsk and pacific okhotsk data are regarded as eurasia north america and pacific north america data respectively the model with an okhotsk plate fits the data better than one in which this region is treated as part of the north american plate because the improved fit exceeds that expected purely from the additional plate the data indicate that the okhotsk plate can be resolved from the north american plate the motions on the okhotsk plate s boundaries predicted by the best fitting euler vectors are generally consistent with the recent tectonics the eurasia okhotsk pole is located at northernmost sakhalin island and predicts right lateral strike slip motion on the nne striking fault plane of the may 27 1995 neftegorsk earthquake consistent with the centroid moment tensor focal mechanism and the surface faulting along the northern boundary of the okhotsk plate the north america okhotsk euler vector predicts left lateral strike slip consistent with the observed focal mechanisms on the nw boundary of the okhotsk plate the eurasia okhotsk euler vector predicts e w extension discordant with the limited focal mechanisms and geological data this misfit may imply that another plate is necessary west of the magadan region in southeast siberia but this possibility is hard to confirm without further data such as might be obtained from space based geodesy

shear wave splitting beneath south kamchatka during the 3 year period associated with the 1997 kronotsky earthquake abstract shear wave splitting measurements in south kamchatka during the 3 year period 1996 1998 in which the kronotsky earthquake m 7 7 december 5 1997 occurred are used to determine anisotropic parameters of the subduction zone and shear wave splitting variations with time the local small seismic events recorded at the petropavlovskaya iris station pet were analyzed the dominant azimuths of the fast shear wave polarizations for the 3 year period are defined within n95 15 e which are consistent with the general pacific plate motion direction modeling of fast shear wave polarizations shows that hti model with the symmetry axis oriented along n15 e 10 fit well the observed data for events the focal depths of which are less than 80 km for the greater depths the orthorhombic symmetry of medium is not excluded the anisotropy coefficient increases generally with depth from 1 2 in the crust to 4 7 5 in the subducting plate variations in time delays show a general increase up to 10 15 ms km during 1996 1997 before the large crustal earthquake series m 5 5 7 in the avacha bay and before the kronotsky earthquake analysis of fast s wave azimuths of mantle events reveals a temporal cyclic variation the most regular variations are observed for fast azimuths of deep events with a period of about 172 days over the 3 year period the fast polarizations of crustal events behave comparatively stable it is assumed that the major instabilities in stress state are localized in the descending slab and influenced the upper mantle and comparatively stable crust

petrology and geochemistry of silurian triassic sedimentary rocks in the tongling region of eastern china their roles in the genesis of large stratabound skarn ore deposits abstract this paper describes the petrology and geochemistry of the silurian triassic sedimentary rocks in the tongling area in eastern china aiming to establish a genetic link between different stratabound skarn deposits and sedimentary lithologies the results from this study show that some devonian triassic transitional lithological units with compositions varying between siliceous rock and carbonate especially thinly layered impure carbonate control the distribution of some large stratabound skarn ore deposits in the tongling region interlayer detachment faults in the transitional lithology rocks are particularly important controlling the final locations of the deposits the transitional lithological zones may have also served as source rocks likely providing some ore forming metals to the deposits gypsum evaporites in rocks from carboniferous sources may have supplied some sulphur to the hydrothermal systems five of such transitional lithological units enriched in organic matter are spatially and closely associated with some large stratabound skarn ore deposits in the tongling region suggesting that organic matter may have served as an absorbent or reducing agent during ore formation

independent active microplate tectonics of northeast asia from gps velocities and block modeling 1 independent okhotsk and amurian microplate motions are tested using velocities from 123 gps sites 80 from within the proposed okh and amu plate boundaries used to constrain the plate kinematics of northeast asia a block modeling approach is used to incorporate both rigid block rotation and near boundary elastic strain accumulation effects in a formal inversion of the gps velocities models include scenarios with and without independent okh and amu plate motion our modeling favors scenarios with independent okh and amu motion based on the application of f test statistics the independent okh plate rotates 0 231 deg myr clockwise with respect to north america about a pole located north of sakhalin the modeled amu plate rotates 0 298 deg myr counterclockwise with respect to nam about a pole located west of the magadan region the plate motion parameters of the independent plates are consistent with the kinematics inferred from earthquake focal mechanism solutions along their boundaries

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

from 2d to 3d prospectivity modelling in the taupo volcanic zone new zealand abstract a 2d prospectivity model of epithermal gold mineralisation has been completed over the taupo volcanic zone tvz using the weights of evidence modelling technique this study was used to restrict a 3d geological interpretation and prospectivity model for the ohakuri region the tvz is commonly thought of as a present day analogue of the environment in which many epithermal ore deposits such as in the hauraki goldfield coromandel volcanic zone are formed the models utilise compiled digital data including historical exploration data geological data from the institute of geological and nuclear sciences ltd quarter million mapping programme recent glass earth geophysics data and historic exploration geochemical data including rock chip and stream sediment information spatial correlations between known deposits and predictive maps are determined from the available data which represent each component of the currently accepted mineral system model for epithermal gold the 2d prospectivity model confirms that the tvz has potential for gold mineralisation however one of the weaknesses of this weights of evidence model is that the studies are carried out in 2d with an approximation of 3d provided by geophysical and drilling data projected to a 2d plane consequently a 3d prospectivity model was completed over the ohakuri area constrained by the results of the 2d model and predictive maps the 3d model improved the results allowing more effective exploration targeting however the study also highlighted the main issues that need to be resolved before 3d prospectivity modelling becomes standard practise in the mineral exploration industry the study also helped develop a work flow that incorporates preliminary 2d spatial data analysis from the weights of evidence technique to more effectively restrict and develop 3d predictive map interpretation and development

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

initial results from wing the continuous gps network in the western pacific area to investigate tectonic deformation in the western pacific a continuous gps tracking network has been established and named the western pacific integrated network of gps wing between 1995 and march 1997 we establised ten new sites data for the period july 1995 to october 1996 were analyzed together with data from international gps service for geodynamics igs global sites to estimate daily coordinates a fiducial free approach was used to obtain the most accurate baseline estimates to fix the estimated coordinates to the terrestrial reference frame the tsukuba igs site is assumed to be moving westward relative to the stable eurasian continent at 2 cm yr according to heki s 1996 estimate we find that 1 velocities of sites well within oceanic plates are in good agreement with rigid plate motion models 2 sites close to plate boundaries are all affected by the deformation at those boundaries among which back arc rifting spreading is clearly visible at the mariana and okinawa troughs 3 sites in eastern asia are moving east to east southeast relative to the stable eurasian continent suggesting long distance effects of the northward collision of india with asia

layered anisotropy within the crust and lithospheric mantle beneath the sea of japan abstract continental rifting during the oligocene to mid miocene caused the opening of the sea of japan and the separation between the japanese islands and the eurasian plate the tectonic evolution in the sea of japan is important for understanding the evolution of back arc regions in active convergent margins here we use data from the seismic stations surrounding the sea of japan to map the rayleigh wave azimuthal anisotropy in the crust and lithospheric mantle beneath the sea of japan we explore the variations of rayleigh wave phase velocity beneath the sea of japan in a broad period range 30 80 s rayleigh wave dispersion curves are measured by the two station technique for a total of 231 interstation paths using vertical component broad band waveforms at 22 seismic stations around the sea of japan from 1411 global earthquakes the resulting maps of rayleigh wave phase velocity and azimuthal anisotropy allow the examination of azimuthal anisotropy at specific periods they exhibit several regions with different isotropic and anisotropic patterns the japan basin displays fast velocities at shorter periods 30 and 40 s with nne ssw anisotropy whereas at 60 s and longer the velocities become slow even if the anisotropy remains ne sw the east china sea shows fast velocities at all periods 30 80 s with constant nw se anisotropy trench normal anisotropy beneath the japanese islands is found at short periods 30 40 s and become trench parallel at periods of 60 s and longer overall our model resolves two layers of anisotropy the shallowest and deepest layers being potentially related to frozen deformation due to recent geodynamic events and asthenospheric flow respectively

three dimensional mineral prospectivity modeling for targeting of concealed mineralization within the zhonggu iron orefield ningwu basin china abstract the zhonggu iron orefield is one of the most important iron orefields in china and is located in the south of the ningwu volcanic basin within the middle and lower yangtze metallogenic belt of eastern china here we present the results of new 3d prospectivity modeling that enabled the delineation of areas prospective for exploration of concealed and deep seated baixiangshan type mineralization and yangzhuang type mineralization within the zhonggu orefield both of these deposits are kiruna type fe apatite deposits but are hosted by different formations within the ningwu basin the modeling approach used during this study involves 3 steps 1 combining available geological and geophysical data to construct 3d geological models 2 generation of 3d predictive maps from these 3d geological models using 3d spatial analysis and 3d geophysical methods 3 combining all of the 3d predictive maps using logistic regression to create a prospectivity map this approach integrates a large amount of available geoscientific data using 3d methods including 3d geological modeling 3d 2d geophysical methods and 3d spatial analysis and data integration methods the resulting prospectivity model clearly identifies highly prospective areas that not only include areas of known mineralization but also a number of favorable targets for future mineral exploration the 3d prospectivity modeling approach showcased within this study provides an efficient way to identify camp scale concealed and deep seated exploration targets and can easily be adapted for regional and deposit scale targeting

machine learning predictive models for mineral prospectivity an evaluation of neural networks random forest regression trees and support vector machines abstract machine learning algorithms mlas such us artificial neural networks anns regression trees rts random forest rf and support vector machines svms are powerful data driven methods that are relatively less widely used in the mapping of mineral prospectivity and thus have not been comparatively evaluated together thoroughly in this field the performances of a series of mlas namely artificial neural networks anns regression trees rts random forest rf and support vector machines svms in mineral prospectivity modelling are compared based on the following criteria i the accuracy in the delineation of prospective areas ii the sensitivity to the estimation of hyper parameters iii the sensitivity to the size of training data and iv the interpretability of model parameters the results of applying the above algorithms to epithermal au prospectivity mapping of the rodalquilar district spain indicate that the rf outperformed the other mla algorithms anns rts and svms the rf algorithm showed higher stability and robustness with varying training parameters and better success rates and roc analysis results on the other hand all mla algorithms can be used when ore deposit evidences are scarce moreover the model parameters of rf and rt can be interpreted to gain insights into the geological controls of mineralization

exploration targeting for orogenic gold deposits in the granites tanami orogen mineral system analysis targeting model and prospectivity analysis abstract a major challenge for mineral exploration geologists is the development of a transparent and reproducible approach to targeting exploration efforts particularly at the regional to camp scales in terranes under difficult cover where exploration and opportunity costs are high in this study a three pronged approach is used for identifying the most prospective ground for orogenic gold deposits in the paleoproterozoic granite tanami orogen gto in western australia a key input to the analyses is the recent development of a 4d model of the gto architectural evolution that provides new insights on the spatio temporal controls over orogenic gold occurrences in the area in particular on the role of pre mineralization pre 1795 ma d gtoe d gto1 d gto2 architecture in localization of gold deposits and the spatial distribution of rock types in 3d this information is used to build up a model of orogenic gold minerals system in the area which is then integrated into the three mutually independent but complementary mineral prospectivity maps namely a concept driven manual and fuzzy analysis and a data driven automated analysis the manual analysis involved 1 generation of a process based gold mineral systems template to aid target selection 2 manual delineation of targets 3 manual estimation of the probability of occurrence of each critical mineralization process based on the available information and 4 combining the above probabilities to derive the relative probability of occurrence of orogenic gold deposits in each of the targets the knowledge based geological information system gis analysis attempts to replicate the expert knowledge used in the manual approach but queried in a more systematic format to eliminate human heuristic bias this involves representing the critical mineralization processes in the form of spatial predictor maps and systematically querying them through the use of a fuzzy logic model to integrate the predictor maps and to derive the western gto orogenic gold prospectivity map the data driven empirical gis analysis uses no expert knowledge instead it employs statistical measures to evaluate the spatial associations between known deposits and predictor maps to establish weights for each predictor layer then combines these layers into a predictive map using a weights of evidence wofe approach application of a mineral systems approach in the manual analysis and the fuzzy analysis is critical potential high value targets identified by these approaches in the western gto lie largely under cover whereas traditional manual targeting is biased to areas of outcrop or sub crop amenable to direct detection technology such as exploration geochemistry and therefore towards areas that are data rich the results show the power of combining the three approaches to prioritize areas for exploration while the manual analysis identifies and employs human intuition and can see through incomplete datasets it is difficult to filter out human bias and to systematically apply to a large region the fuzzy method is more systematic and highlights areas that the manual analysis has undervalued but lacks the intuitive power of the human mind that refines the target by seeing through incomplete datasets the empirical woe method highlights correlations with favorable host stratigraphy and highlights the control of an early set of structures potentially undervalued in the knowledge driven approaches yet is biased due to the incomplete nature of exploration datasets and lack of abundant gold deposits due to the extensive cover the results indicate that the most prospective areas for orogenic gold in western gto are located in the central part of the study area largely in areas blind to previous exploration efforts according to our study the procedure to follow should be to undertake the analyses in the following order manual prospectivity analysis followed by the conceptual fuzzy approach followed by the empirical gis based method undertaking the manual analysis first is important to prevent explorationists from being biased by the automated gis based outputs it is however emphasized that all of the prospectivity outputs from these three methods are possible and they should not be treated as treasure maps but instead as decision support aids therefore a final manual prospectivity analysis redefined by the mutual consideration of output from all of the methods is required the strategy employed in this study constitutes a new template for best practice in terrane to camp scale exploration targeting that can be applied to different terranes and deposit types particularly in terranes under cover and provides a step forward in managing uncertainty in the exploration targeting process

preliminary analysis of deformation at the eurasia pacific north america plate junction from gps data summary since 1996 a network of nine permanent gps receivers has been recording in continuous mode the deformation on kamchatka peninsula the velocity and direction of the relative displacement of observation points are estimated from the entire data set for 1996 2000 the deformation related to the large kronotskoe earthquake mw 7 8 1997 december 5 was identified at distances up to a few hundred kilometres half a month before this major event large amplitude pre seismic deformation appeared at stations closest to its epicentral area the deformation corresponds approximately to a double couple slow event with mw 7 7 located in the foreshock area with an orientation that differs significantly from that of the main shock clear coseismic displacements were also observed they match well those predicted by the published harvard cmt solution large scale post seismic deformation was also recorded again with a duration of about half a month and a cumulative moment comparable to that of the main shock in addition to the transient effects of a large earthquake data show a secular trend that reflects both the continuous plate motion and the elastic response to interplate coupling preliminary estimates of relative plate velocities for the north america okhotsk and beringia plates are given based on the data from stations distant from the most active plate boundaries other stations seem to show mainly the elastic response of the okhotsk and beringia plates to their coupling with the subducting pacific plate at one station at least the velocity of continuous motion underwent a significant change at the time of the kronotskoe earthquake probably indicating a related change in interplate coupling or the effects of mantle rheology

cooling cycles heinrich event 1 and the desiccation of lake victoria abstract east africa s enormous lake victoria dried out at the close of the last glacial but the precise timing and origin of that drying event have not been clarified largely because of uncertainty regarding core stratigraphy and ancient carbon effects on 14 c dates from the lake new dates and re examination of evidence from widely distributed cores shows that desiccation occurred some time between 15 900 and 14 200 calendar years bp and perhaps also ca 18 17 kyr bp these lake level minima were briefer than has been previously suggested and were synchronous with pronounced global climate disruptions including north atlantic ice rafting heinrich event 1 less severe declines occurred during the older and younger dryas intervals dansgaard oeschger type cooling cycles registered in the gisp2 ice core record tracked major lake level regressions in east africa and weakenings of afro asian monsoons during the late quaternary possibly linking the desiccation of lake victoria to century scale reductions in solar radiation output

application of a hybrid method combining multilevel fuzzy comprehensive evaluation with asymmetric fuzzy relation analysis to mapping prospectivity abstract a case application of a hybrid method combining multilevel fuzzy comprehensive evaluation with asymmetric fuzzy relation analysis is demonstrated to map porphyry copper prospectivity in the gangdese district tibet western china two level binary geoscience variables including favorable rocks intrusive rocks faults and geochemical anomalies are identified based on porphyry copper mineral deposit model and ranked using asymmetric fuzzy relation analysis the prospective target areas are identified by fuzzy membership values greater than 0 82 and corresponding uncertainty less than 0 36 the target areas occupy only 7 0 of the study area but contain 52 4 of the total number of known deposits the prospectivity map illustrates that the targets are not only directly associated with the known deposits in the central part of the study area but also with e w and n e oriented faults in the northern part of the study area the targets can be used to guide further exploration for undiscovered porphyry copper in gangdese district

active faults in eurasia general remarks abstract the database and map of active faults of eurasia 1 5 000 000 have been compiled according to the ilp project ii 2 world map of major active faults the map shows the complicated distribution of active faulting the major faults group in broad mobile belts between relatively weakly faulted parts of the main plates the faults form the plates microplates and crustal blocks boundaries there and are accompanied by deformation of the boundary areas using active fault data for the seismic hazard assessment estimation of maximum possible magnitudes of earthquakes in fault zones it is necessary to take into account the total neotectonic activity of the territory and average rate and sense of motion on the fault because trenching gives a possibility to determine only vertical earthquake offset on a fault it is necessary to make corrections for strike slip faults to estimate the earthquake magnitude by using this parameter

mapping mineral prospectivity for cu polymetallic mineralization in southwest fujian province china abstract in this study both the fuzzy weights of evidence fwofe and random forest rf methods were applied to map the mineral prospectivity for cu polymetallic mineralization in southwestern fujian province which is an important cu polymetallic belt in china recent studies have revealed that the zijinshan porphyry epithermal cu deposit is associated with jurassic to cretaceous yanshanian intermediate to felsic intrusions and faulting tectonics evidence layers which are key indicators of the formation of zijinshan porphyry epithermal cu mineralization include 1 jurassic to cretaceous intermediate felsic intrusions 2 mineralization related geochemical anomalies 3 faults and 4 jurassic to cretaceous volcanic rocks these layers were determined using spatial analyses in support by geodas and arcgis based on geological geochemical and geophysical data the results demonstrated that most of the known cu occurrences are in areas linked to high probability values the target areas delineated by the fwofe occupy 10 of the study region and contain 60 of the total number of known cu occurrences in comparison with fwofe the resulting rf areas occupy 15 of the study area but contain 90 of the total number of known cu occurrences the normalized density value of 1 66 for rf is higher than the 1 15 value for fwofe indicating that rf performs better than fwofe receiver operating characteristics roc were used to validate the prospectivity model and check the effects of overfitting the area under the roc curve auc was greater than 0 5 indicating that both prospectivity maps are useful in cu polymetallic prospectivity mapping in southwestern fujian province

gis based mineral prospectivity mapping using machine learning methods a case study from tongling ore district eastern china abstract predictive modelling of mineral prospectivity using gis is a valid and progressively more accepted tool for delineating reproducible mineral exploration targets in this study machine learning methods including support vector machine svm artificial neural networks ann and random forest rf were employed to conduct gis based mineral prospectivity mapping of the tongling ore district eastern china the mineral systems approach was used to translate our understanding of the skarn cu mineral system into mappable exploration criteria resulting in 12 predictor maps that represent source transport physical trap and chemical deposition processes critical for ore formation predictive svm ann and rf models were trained by way of predictor maps and corroborated using a 10 fold cross validation the overall performance of the resulting predictive models was assessed in both training and test datasets using a confusion matrix set of statistical measurements receiver operating characteristic curve and success rate curve the assessment results indicate that the three machine learning models presented in this study achieved satisfactory performance levels characterized by high predictive accuracy in addition all models exhibited well interpretability that provided consistent ranking information about the relative importance of the evidential features contributing to the final predictions in comparison the rf model outperformed the svm and ann models having achieved greater consistency with respect to variations in the model parameters and better predictive accuracy importantly the rf model exhibited the highest predictive efficiency capturing most of the known deposits within the smallest prospective tracts the above results suggest that the rf model is the most appropriate model for cu potential mapping in the tongling ore district and therefore was used to generate a prospectivity map containing very high high moderate and low potential areas in support of follow up exploration the prospective areas delineated in this map occupy 13 97 of the study area and capture 80 95 of the known deposits the fact that two newly discovered deposits occur within the prospective areas predicted by the prospectivity model indicates that the model is robust and effective regarding exploration target generation

involvement of old crustal materials during formation of the sakhalin island russian far east and its paleogeographic implication constraints from detrital zircon ages of modern river sand and miocene sandstone abstract in order to decipher crustal nature of the sakhalin island in russian far east we carried out detrital zircon u pb age analyses on miocene sandstone and river sand from the longest river poronay river of the sakhalin island the detrital zircon data from two river sand samples display similar age distribution patterns with a dominant mesozoic age group subordinate age peaks at 1 8 ga and 2 5 ga and a few paleozoic and neoproterozoic grains the miocene sandstone shows age peaks at 22 84 260 and 497 ma respectively and a few paleo proterozoic grains these age groups indicate that abundant old crustal materials have been involved in the crustal formation of the sakhalin island detrital zircon result reveals two episodes of post accretion magmatism from the sakhalin island in ages of 37 ma and 22 21 ma they can be correlated with coeval post accretion magmatic events in the hokkaido island supporting the geological correlation between the sakhalin island and the hokkaido island comparison of detrital zircon dating result from the sakhalin island with those from surrounding blocks and cratons in eastern asia allows us to propose two possible sources in eastern asia the bureya jiamusi khanka block with the sikhote alin orogenic belt to its west and the south china craton the detrital zircon result indicates that the formation of the sakhalin island should be close to the east asia continent rather than as an independent intro oceanic island arc within the pacific ocean similar to formation of the japanese islands the south china craton may have played an important role during formation of the sakhalin island

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

present day kinematics of asia derived from geologic fault rates active fault geometry available quaternary rates on major faults and the far field plate motion are used to determine crustal kinematics in the collision zone between india and asia using a finite element formalism to construct a spherical shell model of the asian continent with embedded faults we seek a velocity solution approaching the motion of rigid blocks by minimizing the elastic strain energy in the fault bounded blocks by doing so we test the assumption that long term deformation within continents is mostly localized into major faults in the solution fault motion accounts for more than 80 of the deformation allowing us to describe our velocity model in terms of quasi rigid block rotations on the sphere south china is rotating clockwise about a pole located southwest of borneo implying an e ese velocity vector of 11 mm yr for a point at shanghai in agreement with the velocity vector determined by very long baseline interferometry heki et al 1995 the eastward movement of south china is accommodated by oblique extension along the red river fault at a rate of 10 5 mm yr in the south and by the combination of left lateral strike slip motion on the qinling dabie shan fault and the counterclockwise rotation of the ordos and adjacent blocks in the north the tarim rotates clockwise with respect to dzungaria about a pole located at 44 n 92 e consistent with increasing crustal shortening toward the west throughout the tien shan assuming incompressibility a crustal volume budget over a domain encompassing the tertiary mountain ranges in asia shows that over the last 10 000 years 73 4 of the north south shortening between india and asia has been absorbed by thickening of the lithosphere and 27 has been accommodated by lateral extrusion of continental blocks the present day predominance of thickening in asia results from the relatively slow eastward motion of south china controlled by strike slip faulting in the qinling shan and oblique extension in northeastern china

new discoveries in dynamics of an m8 earthquake phenomena and their implications from the 2003 tokachi oki earthquake using a long term monitoring cabled observatory at the 2003 tokachi oki earthquake of m8 seafloor phenomena such as a generation process of tsunami seafloor uplifts turbidity current etc were observed using a cabled observatory installed on the seafloor the turbidity current was observed as a benthic storm caused presumably by the mainshock the seafloor uplifts were observed at the mainshock and continuously after the mainshock the uplifts were 0 35 0 37 and 0 12 m for epicentral distances of 25 5 31 4 and 81 7 km respectively after the mainshock a continuous uplift of the seafloor is observed at all three pressure gauge locations indicating that there was a change in the state of friction on the plate boundary interface by the mainshock in this paper we first show what was observed using the cabled observatory installed right above the focal area of the earthquake and then we discuss to summarize these phenomena associated with the earthquake its possible causes and future directions in long term monitoring of seismogenic processes

a tectono genetic model for porphyry skarn stratabound cu au mo fe and magnetite apatite deposits along the middle lower yangtze river valley eastern china abstract the middle lower yangtze river valley metallogenic belt yrb situated along the northern margin of the yangtze craton is characterized by porphyry skarn stratabound cu au mo fe deposits in the areas of uplift and magnetite apatite deposits in cretaceous fault basins following detailed field investigations and a review of published data we recognize two episodes of magmatism and mineralization in the yrb 1 156 137 ma high k calc alkaline granitoids associated with 148 135 ma porphyry skarn stratabound cu au mo fe deposits and 2 135 123 ma shoshonitic series associated with 134 9 122 9 ma magnetite apatite deposits a type granitoids and associated alkaline volcanic have a small age range from 126 5 to 124 8 ma and are temporally spatially and genetically associated with the second episode the geodynamic history of the yrb did not experience the paleozoic to mesozoic lithospheric thickening that took place in the north china craton this process is inferred to be linked to partial melting of the delaminated lower crust at high pressures resulting in the development of c type adakitic rocks the petrochemical and sr nd isotopic data show that both the shoshonitic series and a type granitoids are quite different from adakites with only some of the k calc alkaline granitoids having adakitic signatures previous ore genesis models were established based on an assumed relationship with adakites and a continuous tectono thermal evolution from 150 to 100 ma all data obtained for the middle lower yangtze river region consistently show that the tan lu regional strike slip fault zone initiated at 233 6 to 225 6 ma from the collision between the north china and yangtze cratons and was reactivated at ca 160 ma the tan lu fault was caused by the oblique subduction of the izanagi plate which along the yrb the low angle subducted slab and the overlying crust was disrupted or broken due to the disharmonious movement of the two blocks the high k calc alkaline granitoids magmas were derived from melting of the subducted slab with some input of crustal material these magmas were emplaced at the intersections between ne and ew trending faults and formed porphyry skarn stratabound cu au mo fe deposits between 156 and 137 ma after 135 ma the subducted plate changed its direction of motion to northeast now running parallel to the eurasian continental margin and leading to large scale continental extension the shoshonitic series and subsequent a type granitoids magmatism and the development of magnetite apatite ores in the yrb took place in both fault basins and ne trending rifts between 135 and 124 ma

are post seismic effects of the m 8 4 bolnay earthquake 1905 july 23 still influencing gps velocities in the mongolia baikal area summary gps measurement campaigns in the mongolia baikal area show that 1 the baikal rift zone is currently opening at 4 5 mm yr 1 in a nw se direction and 2 the western part of the amurian north china block is moving eastward relative to eurasia at 5 7 mm yr 1 these results are consistent with recent geodetic studies in asia and indicate that crustal motions in mongolia and north china derived from geodetic measurements are significantly faster than those proposed by most deformation models of asia using a numerical model we test whether post seismic deformation caused by viscoelastic relaxation in the lower crust following the tsetserleg bolnay earthquake sequence mw 7 9 and 8 4 1905 july can explain this discrepancy we find that surface velocities at the gps sites presented here for the 1997 2000 time period can reach 4 mm yr 1 depending on the earthquake source parameters and the rheology used in the models using a model based on our best current knowledge of lithospheric structure and rheology in the mongolia baikal area we find that the contribution of post seismic effects to the gps velocities presented here is less than 2 mm yr 1 for the mongolian sites and less than 1 mm yr 1 for the baikal sites we therefore conclude that the post seismic effects of the mw 8 4 1905 bolnay earthquake cannot explain why the gps derived crustal motions in mongolia and the baikal rift zone are significantly larger than those proposed by deformation models of asia this discrepancy must therefore be sought in processes not accounted for in most of these deformation models such as the farfield contribution of the pacific subduction zones and or the effect of gravitational forces on intracontinental deformation

linking mineral deposit models to quantitative risk analysis and decision making in exploration this paper describes a methodology of translating mineral deposit models into flexible probabilistic structures based on 1 extraction of ore components fluids metals and ligands from crustal or mantle sources or both 2 fluid or melt assisted transport of ore components from source to trap zones 3 formation of trap zones i e effective melt or fluid channels that can focus melt or fluid migration and accommodate large amounts of metal and 4 operation of the physicochemical processes that promote and sustain the deposition of metal from fluids or melts passing through a particular trap site our approach integrates these critical mineralization processes and conditions with concepts of probability theory decision analysis and financial modeling the principal objective is to make mineral deposit models amenable to financial risk and value analysis and suitable for communication of value creating geologic concepts to financial stakeholders in economic terms a case study based on an actual porphyry copper project illustrates how the resulting probabilistic mineral systems model can generate a measure of the probability of ore occurrence as an input for exploration decision trees and simulations to calculate the expected value of an exploration project and the probability distribution of all possible surrounding net present values npvs within a minimum and maximum range formulation of the probabilistic model closely follows and combines principles of the well established petroleum and mineral systems approaches and makes use of excel based model templates with decision tree and simulation add in software packages

horizontal and vertical crustal movements from three dimensional very long baseline interferometry kinematic reference frame implication for the reversal timescale revision three dimensional kinematic reference frame of geodetic very long baseline interferometry vlbi stations tied to a geologic plate motion model was established using the glb907 solution by first selecting globally distributed stable plate interior stations and then applying a small translation and a rotation for the entire network in a three dimensional space so that the differences in the horizontal velocities between the vlbi observations and the model predictions are minimized since the vlbi network is global we only assume that the horizontal movements of technically stable stations obey a plate motion model we need not introduce any unwarranted constraints to the vertical velocities of specific stations to realize the frame a suggestive correlation was found between the estimated vertical velocities of north american stations and those predicted by a postglacial rebound model the revision of the magnetic polarity timescale mpts causes a uniform increase or decrease of the predicted velocities which could be detected as the small difference between the measured and the predicted relative plate velocities direct estimation of the correction suggests that the vlbi data fit best to the model when the nuvel1 model is corrected by 3 4 1 2 which differs significantly from the 4 5 deduced from the astronomical mpts calibration this was further confirmed by estimating the rotation rates for individual plate pairs

tertiary geodynamics of sakhalin nw pacific from anisotropy of magnetic susceptibility fabrics and paleomagnetic data abstract sakhalin has been affected by several phases of cretaceous and tertiary deformation due to the complex interaction of plates in the northwest pacific region a detailed understanding of the strain is important because it will provide constraints on plate scale processes that control the formation and deformation of marginal sedimentary basins anisotropy of magnetic susceptibility ams data were obtained from fine grained mudstones and siltstones from 22 localities in sakhalin in order to provide information concerning tectonic strain ams data reliably record ancient strain tensor orientations before significant deformation of the sediments occurred paleomagnetically determined vertical axis rotations of crustal rocks allow rotation of the fabrics back to their original orientation results from southwest sakhalin indicate a n035 e directed net tectonic transport from the mid paleocene to the early miocene which is consistent with the present day relative motion between the okhotsk sea and eurasian plates reconstruction of early late miocene ams fabrics in east sakhalin indicates a tectonic transport direction of n040 e in west sakhalin the transport direction appears to have remained relatively consistent from the oligocene to the late miocene but it has a different attitude of n080 e this suggests local deflection of the stress and strain fields which was probably associated with opening of the northern tatar strait a northward directed tectonic transport is observed in miocene sediments in southeast sakhalin mid eocene sediments in east sakhalin and in late cretaceous rocks of west and northern sakhalin which may be associated with northwestward motion and subduction of the pacific plate in the tertiary period the boundaries of the separate regions defined by the ams data are consistent with present day plate models and therefore provide meaningful constraints on the tectonic evolution of sakhalin

arc continent collision and subduction reversal in the cenozoic evolution of the northwest pacific an example from kamchatka ne russia abstract the principal new feature in the cenozoic evolution of the northwest pacific is based on the fact that two arc terranes of upper cretaceous paleogene age were incorporated in the kamchatka orogen during the early tertiary and at the end of the miocene respectively these two arc terranes so called achaivayam valaginskaya campanian lower paleocene and kronotskaya coniacian eocene arcs are separated by a suture zone that contains deformed slices of young paleocene lower eocene oceanic crust paleomagnetic data on the original paleolatitudes of the arc positions as well as geochemical data characterized the arcs as intraoceanic originated in the northwest pacific the arcs were separated by the vetlovka oceanic plate suggested to be a trapped fragment of the kula plate in which a new spreading zone developed in the early tertiary the principal event in the reconstructed evolution is the eocene collision of the extended achaivayam valaginskaya arc terrane with the continental margin of asia the margin is interpreted as the southeastern facing the pacific cretaceous accretionary boundary of the okhotsk microplate docked against the asian continent at 55 65 ma the arc continent collision developed progressively northward from the end of the paleocene early eocene in southern kamchatka to the middle eocene in the olutorka region the different stages of the collision occurred simultaneously along strike of the achaivayam valaginskaya arc according to the geodynamic model based on geological data for southern kamchatka collision included 1 the entrance of the continental margin in the subduction zone deformation of the overriding plate and subduction of fore arc block 2 arc obduction on the continental margin blocking of continental margin subduction and 3 subduction reversal with onset of oceanic subduction at the eastern side of the deformed arc this subduction reversal produced deformation and reverse faulting along the eastern side of the arc thus allowing accretion of tectonic slices of young oceanic crust of the vetlovka plate which began to subduct during the subduction reversal the subducted plate dipping to the southeast was broken off and detached at depth under the arc area the subduction polarity reversal the most characteristic feature of the collision model is strongly supported by structural and geologic data of southern kamchatka and explains the main tectonic metamorphic and magmatic events related to and postdating the collision

comparing prospectivity modelling results and past exploration data a case study of porphyry cu au mineral systems in the macquarie arc lachlan fold belt new south wales mineral exploration is undertaken in stages with each stage designed to get to the next decision point of whether or not to keep exploring a particular area based on the results at hand as a general rule each consecutive exploration stage is more expensive due to the progressively more drill and study intensive nature of the work required in particular after discovery of a potentially economic mineral deposit as such the distribution of exploration activities and related expenditures essentially serve as a spatial measure of prospectivity as perceived by mineral exploration companies in this study we compare historic 1980 to 2002 porphyry cu au exploration activities and expenditures in part of the ordovician to early silurian macquarie arc australia s most significant porphyry province with total resources greater than 80 moz of au and 13 mt of cu to prospectivity modelling results from a weights of evidence wofe model the outcomes of this spatial and statistical comparison indicate that at 2002 the macquarie arc was by no means a mature exploration destination and that past exploration investment outside the main mining areas was not necessarily effective moreover no spatial correlation was apparent between areas of higher exploration expenditure and greater geological potential for example of the 692 km2 of highly prospective ground covered by the exploration licences examined in this study only 89 km2 c 13 have been explored effectively in that they received some form of drilling interestingly the remaining area 603 km2 or c 87 had not yet been effectively tested as such our analysis confirmed that despite a greater 100 year exploration and mining history much of the prospective ground within the study area remained untested taken as a whole the results of our spatial and statistical comparison are important inputs for assessing the effectiveness of exploration investment and explanation maturity and therefore future exploration decision making the outcomes also have implications for strategic planning of future government legislation helping to manage and maximise the benefits from exploration investment

velocity field of around the sea of okhotsk and sea of japan regions determined from a new continuous gps network data to investigate the current crustal movements in and around the sea of okhotsk and sea of japan regions we have established a continuous gps network by the end of 1997 the network had been expanded to include 12 new stations data for the period from july 1995 to november 1997 were analyzed together with data from international gps service for geodynamics igs global stations to fix the estimated coordinates to the terrestrial reference frame the tsukuba igs station was assumed to be moving westward relative to the stable eurasian continent at 2cm yr according to heki s l996 estimate we find that 1 stations in the western margin of the sea of japan have eastward velocity vectors 2 the pole position of the okhotsk plate is located near okha which reconfirms the okhotsk micro plate 3 a plate boundary of the okhotsk and amurian plates between southen sakhalin and hokkaido is suggested

tectonic stress state in ne japan as part of the okhotsk plate abstract an existing geodetic flow velocity model obtained by using an internal free network adjustment technique is used to derive estimates for various strain rates parameters in ne japan the greatest shortening rates of the principal strains trending e w are located in regions where much steady internal frame invariant plastic flow deformation is observed to be taking place the internal geodetic adjustment technique yielded the internal deformation in the tohoku arc most of the intraplate deformations including the much folding deformations observed in the inner zone are produced from within an interseismic transient elastic loading at a strongly coupled locked japan trench would not be needed the observed ongoing extensive ductile folding deformation in the inner zone of tohoku may mean that the geodetic strain rates causing shortening at 2 3 cm yr probably reflect the more correct level of the deformation which is steady permanent in ne japan as compared with seismic faulting data which indicate 0 5 cm yr shortening the calculated principal strain rates are used to make an interpretation for the origin of the deviatoric principal stresses within the greater regional plate tectonic framework the tectonic stress state in ne japan as part of the okhotsk plate could mostly be influenced by the okhotsk plate which is extruding southward to lessen the significant accumulated contractional deformation in ne asia in the verkhoyansk cherskii mountains the principal strain rates are n s extensional essentially everywhere in ne japan as a result of the southerly extrusion except in its southernmost leading edge in the uetsu fossa magna province where the japan alps rampart rises in front of the extrusion here an e w compressional stress state prevails a second e w contractional zone is found in north central tohoku extending from the sanriku province in the outer zone to the inner zone in the japan sea side being more prevalent in the latter zone the calculated rotation rates from the geodetic flow model are clockwise cw in both of the e w contractional regions ne japan extruding southward faces buttresses in 1 the oga ojika line ool and or a crustal weakness zone between the northern and the southern halves of tohoku approx at 38 5 n latitude and especially 2 the japanese alps rampart these obstacles cause the northern and southernmost tohoku to veer to its right and rotate cw thereby setting up the e w trending compressional deformation in their respective inner zones between the ool or the 38 5 n boundary and the kanto tectonic line ktl the sense of the differential rotations is counterclockwise ccw towards the ocean to the se the northern tohoku north of the ool and the southernmost tohoku south of the ktl cannot rotate ccw towards the ocean because of the izu block s collision in the south and the relatively strong coupling along the subduction interface beneath the japan trench in the north off sanriku the relatively stronger long term coupling between the northern tohoku and the pacific plate at the sanriku coast with respect to that in off fukushima is due to a flatter subduction of the pacific slab there increasing the plates interface contact area the flattening of the subduction dip angle was caused by ccw rotation and shifting of the northern tohoku along the dextral honjo matsushima line roughly corresponding to the ool towards the pacific and overriding of the subduction zone during the formation of the japan sea

seismicity of the bering strait region evidence for a bering block newly compiled russian and u s seismological data support an independent bering block in motion relative to the north american plate this motion is likely to be driven by the westward extrusion of southwestern alaska resulting from compression in southern alaska due to subduction of the pacific plate and terrane accretion seismicity extends from central alaska through the bering strait and into chukotka in eastern chukotka several southwest trends are evident some of which continue through the koryak highlands to kamchatka the seismicity outlines the bering block which includes most of the bering sea chukchi peninsula seward peninsula and parts of western alaska focal mechanisms young basaltic volcanism and normal faults in western alaska and chukotka indicate that the bering strait is under northeast southwest extension this in conjunction with thrust faulting in the koryak highlands indicates that the bering block is rotating clockwise relative to the north american plate

aeromagnetic 3d inversion imaging for intermediate acid intrusive bodies and its indication significance of deep ore prospecting in tongling ore concentration district in the tongling ore concentration district the intrusions are closely related to metallogenic activities and almost all endogenic metallic ore deposits it is hence of great significance to find and delineate concealed and semi concealed intermediate acid intrusive bodies in the new round of mineral exploration the 3d inversion imaging technique was applied in tongling based on 1 50 000 aeromagnetic data in order to detect intermediate acid intrusive bodies based on the inversion result the authors selected a suitable magnetic susceptibility boundary in combination with physical properties of the rocks as well as geological information identified 34 intermediate acid intrusive bodies and studied their 3d spatial shapes most of the intermediate acid intrusive bodies are consistent with geological mapping results at surface the inversion results not only reflect the distribution of the intermediate acid intrusive bodies at surface but also indicate their 3d spatial shapes at depth according to the horizon intrusive body prospecting model in combination with other metallogenic information 6 principles were established in search for ore prospect areas at depth based on rock bodies inferred by the aeromagnetic 3d inversion 6 deep prospecting areas were delineated and the data obtained provide important information for deep prospecting in the tongling ore concentration district

selection of coherent deposit type locations and their application in data driven mineral prospectivity mapping data driven prospectivity mapping can be undermined by dissimilarity in multivariate spatial data signatures of deposit type locations most cases of data driven prospectivity mapping however make use of training sets of randomly selected deposit type locations with the implicit assumption that they are coherent i e with similar multivariate spatial data signatures this study shows that the quality of data driven prospectivity mapping can be improved by using a training set of coherent deposit type locations analysis and selection of coherent deposit type locations was performed via logistic regression by using multiple sets of deposit occurrence favourability scores of univariate geoscience spatial data as independent variables and binary deposit occurrence scores as dependent variable the set of coherent deposit type locations and three sets of randomly selected deposit type locations were each used in data driven prospectivity mapping via application of evidential belief functions the prospectivity map based on the training set of coherent deposit type locations resulted in lower uncertainty better goodness of fit to the training set and better predictive capacity against a cross validation set of economic deposits of the type sought this study shows that explicit selection of training set of coherent deposit type locations should be applied in data driven prospectivity mapping

new constraints on current deformation in asia from continuous gps measurements at ulan baatar mongolia on the basis of 3 years of continuous gps measurements 1995 1998 show a velocity of 6 4 1 6 mm yr in a n125 30 azimuth with respect to eurasia at a permanent site in ulan baatar mongolia together with recent gps results in asia this result indicates motion of the amurian north china block at 6 10 mm yr to the east to southeast relative to eurasia 0 to 5mm yr slower than south china 10 11 mm yr eastward the small differential motion between these two blocks is in agreement with deformation models of asia where crustal thickening dominates lateral extrusion the fact that the velocity of the amurian north china block is significantly faster than the predictions of models based on the hypothesis that deformation in asia is enterely driven by the india eurasia collision suggests that other mechanisms such as far field effects of subduction processes and gravitational forces could significantly contribute to intracontinental deformation