modeling susceptibility to landslides using the weight of evidence approach western colorado usa abstract the paonia mcclure pass area of colorado is well known for active mass movements we examined 735 active shallow movement features including debris flows debris slides rock slides and soil slides in this area identification of the hazardous areas is a fundamental component of disaster management and an important basis for promoting safe human occupation and infrastructure development in landslide prone areas bayes theorem based on the weight of evidence woe was used to create a map of landslides that could be hazardous the modeling was accomplished by employing a geographical information system gis and a statistical package seventeen factors that cause landslides were measured and weighted using the woe method to create a map of areas susceptible to landslides the maps of weighted factors were summed on a pixel by pixel basis after performing chi square tests to determine factors that are conditionally independent of each other by combining factors that represent topography hydrology geology land cover and human influences six models were developed the performance of each model was evaluated by the distribution of the observed landslides the validity of the best map was checked against landslides which were not entered in the analysis the resulting map of areas susceptible to landslides has a prediction accuracy of 78

precambrian basement geology of the permian basin region of west texas and eastern new mexico a geophysical perspective because most of the permian basin region of west texas and southern new mexico is covered by phanerozoic rocks other means must be found to examine the precambrian upper crustal geology of the region we have combined geologic information on the precambrian from outcrops and wells with geophysical information from gravity and magnetic surveys in an integrated analysis of the history and structure of basement rocks in the region geophysical anomalies can be related to six precambrian events formation of the early proterozoic outer tectonic belt igneous activity in the southern granite rhyolite province an episode of pre grenville extension the grenville orogeny rifting to form the delaware aulacogen and eocambrian rifting to form the early paleozoic continental mar in two geophysical features were studied in detail the abilene gravity minimum and the central basin platform gravity high the abilene gravity minimum is shown to extend from the delaware basin across north central texas and is interpreted to be caused by a granitic batholith similar in size to the sierra nevada batholith in california and nevada this batholith appears to be related to formation of the southern granite rhyolite province possibly as a continental margin arc batholith because of this interpretation we have located the grenville tectonic front southward from its commonly quoted position closer to the llano uplift middle proterozoic mafic intrusions are found to core the central basin platform and the roosevelt uplift these intrusions formed at about 1 1 ga and are related in time to both the mid continent rift system and the grenville orogeny in texas because these features are likely to be rift related they suggest that the concept of a delaware aulacogen needs to be revised only to the extent that the rifting is proterozoic in age not eocambrian precambrian basement structures and changes in lithology have influenced the structure and stratigraphy in the overlying permian basin and thus have potential exploration significance interpretation of the gravity and magnetic data with geologic information also leads us to suggest the existence of pre ellenburger basins which may be extensive and of potential exploration interest

modification of continental lithosphere by tectonic processes a tomographic image of central north america the assembly of laurentia by precambrian accretion is also believed to have formed the underlying lithosphere accretionary signatures are detectable by seismic observations but subject to modification by later processes e g orogeny rifting and plumes we examine the archean superior province sp and environs using a set of teleseismic p wave arrivals from canadian and american instruments the resulting tomographic model has high resolution beneath the dakotas and minnesota provides a first look at the lithosphere beneath manitoba and sharpens previously documented features in ontario from the model and previous anisotropy observations we detect i a large high velocity feature beneath the western sp associated with elevated lithospheric anisotropy the high velocity feature does not match crustal boundaries notably its western edge lies approximately 200 km east of the contact with the proterozoic trans hudson orogen tho ii a low velocity channel shaped feature strikes northwest through minnesota and the dakotas associated with weakening anisotropy iii high velocities southwest of ii beneath the minnesota river valley terrane mrvt associated with low anisotropy we interpret i to be accretionary and contemporaneous with superior assembly similar velocity but weaker anisotropy of the mrvt is consistent with vertical tectonic mechanisms the inboard location of the tho contact may indicate modification of the superior root the low velocity channel has no obvious crustal expression but connects to an offset in the proterozoic mid continent rift mcr and may be rift related the mcr is not well imaged but will be examined via the temporary superior province rifting earthscope experiment in progress

paleomagnetism of 1 09 ga lake shore traps keweenaw peninsula michigan new results and implications we report paleomagnetic data from a new section of the 1 09 ga lake shore traps exposed on silver island 10 flows and on the adjacent mainland two flows along the northwestern coastline of the

the mesoproterozoic copperwood sedimentary rock hosted stratiform copper deposit upper peninsula michigan copperwood is located in gogebic county upper peninsula michigan within the porcupine mountains copper district it was discovered in 1956 and in 2008 orvana minerals corp began exploration and development work with production projected in the near future stratiform copper mineralization is hosted by gray to black shales and siltstones of the basal nonesuch formation copper mineralization is overlain by laminated gray siltstones of the nonesuch formation and is underlain by red bed sandstones conglomerates and minor siltstones of the copper harbor formation these rocks are part of a thick section of clastic sedimentary rocks that comprise the upper fill of the mesoproterozoic 1 1 1 0 ga midcontinent rift the copper deposit is a tabular body that averages 2 5 m thick lacks significant basal undulations and dips 8 to 12 northward on the southwest limb of the western syncline an open fold with a shallow plunge to the northwest chalcocite is the only cu bearing mineral in the orebody and occurs as concentrations along stratigraphic laminations and as disseminated grains within the orebody there is no mineral or metal zoning cu ag and s are strongly enriched zn is very slightly enriched and pb and co lack enrichment gangue minerals in the orebody are quartz clinochore muscovite illite plagioclase k feldspar calcite and hematite which are consistent with temperatures of less than 130 c only one significant fault a shallow nw dipping reverse fault with displacement of up to 7 m has disturbed the section the mineralized zone at copperwood is stratigraphically equivalent to that at the white pine mine but copperwood lacks the structural complexity and the hydrothermal overprint manifested by the native cu mineralization at white pine reported canadian national instrument 43 101 compliant measured indicated and inferred resources are 33 million metric tonnes mt of 1 60 cu and 4 1 ppm ag for total contained cu of about 1 165 billion lb and 4 32 moz of ag the characteristics of copperwood are consistent with those of reduced facies or kupferschiefer type sedimentary rock hosted stratiform copper deposits the proposed genetic model is chalcocite replacement of pyrite in unlithified sediments during diagenesis as a result of emanating upward focused compaction driven cu bearing saline basinal waters with cu leached from the underlying red bed paleoquifer the simplicity of the mineralizing event and the undeformed nature of the deposit distinguish copperwood from most other examples of reduced facies or kupferschiefer type sedimentary rock hosted stratiform copper deposits throughout the world

tectonic implications of finite strain variations in baraboo interval quartzites ca 1700 ma mazatzal orogen wisconsin and minnesota usa abstract variably deformed baraboo interval quartzites 1750 1630 ma are now correlated by detrital zircon ages holm d schneider d coath c d 1998 age and deformation of early proterozoic quartzites in the southern lake superior region implications for extent of foreland deformation during final assembly of laurentia geology 26 907 910 and were analyzed using finite strain techniques which document a se nw tectonic shortening orientation from the baraboo syncline south to the flambeau syncline north fabric interpretations using bedding and the principal strain axis orientations indicate there was a mix of layer parallel and layer normal synfolding shortening in the plane of tectonic transport se nw in the thrust belt finite strain magnitudes increase from the foreland barron sioux quartzites south toward the baraboo syncline electron backscatter device ebsd fabric diagrams pole figures of quartz optic axes also demonstrate an increasingly penetrative strain to the south anisotropy of low field ac magnetic susceptibility ams as a strain proxy preserve kmin measurements in the baraboo syncline quartzites that are sub horizontal e w and intersect bedding ams measurements in underlying rhyolite on opposite limbs of the baraboo syncline are clean appear to be primary magmatic as kmax intersects bedding but require a complex folding interpretation that is inconsistent with field kinematic indicators the flat lying foreland barron and sioux quartzites preserve a mix of results quartzites with no strain finite strain and ebsd measurements or small strains that preserve vertical shortening ams measurements in the foreland preserve kmin axes that are sub horizontal and parallel to the regional shortening orientation in the adjacent thrust belt the mazatzal orogen produced a thrust belt that is orders of magnitude wider 500 km and of higher metamorphic grade than most thrust belts where both the thrust belt and foreland are quartzites

evaluation of prediction capability of the artificial neural networks for mapping landslide susceptibility in the turbolo river catchment northern calabria italy abstract landslides are one of the most widespread natural hazards that cause damage to both property and life every year and therefore the spatial distribution of the landslide susceptibility is necessary for planning future developmental activities in this paper the artificial neural network ann technique is tested for developing a landslide susceptibility map in turbolo river catchment north calabria south italy landslides were mapped through air photo interpretation and field surveys by identifying both the landslide depletion zones dzs and accumulation zones azs and relevant geo environmental thematic layers pertaining to landslide predisposing factors were generated using air photo interpretation field surveys and geographic information system gis tools ten predisposing factors were related to the occurrence of landslide lithology faults land use drainage network and a series of topographic factors elevation slope aspect plan curvature topographic wetness index twi and stream power index spi in order to evaluate and validate landslide susceptibility the dzs were divided in two groups using a random partition strategy the first group training set was used to prepare the susceptibility map employing a back propagation learning algorithm in the idrisi taiga software the second group testing set was used to validate the landslide susceptibility model using the confusion matrix and the receiver operating characteristic roc curve the susceptibility map was classified into five susceptibility classes very low low moderate high and very high about 46 of the study area falls in high to very high susceptible classes and most of the dzs mapped 87 3 occur in the same classes the validation results showed satisfactory agreement between the susceptibility map and the dzs locations over 85 of the dzs of the validation set are correctly classified falling in high and very high susceptibility areas also the roc curve had shown an area under curve auc value of 0 90 which demonstrates the robustness and good reliability of the landslide susceptibility model according to these results we conclude that the map produced by the artificial neural network is reliable and the methodology applied in the study produced high performance and satisfactory results which may be useful for land planning policy

predictive mapping of prospectivity and quantitative estimation of undiscovered vms deposits in skellefte district sweden mapping of mineral prospectivity and assessment of undiscovered mineral deposits both aim to delineate prospective ground for mineral exploration but the latter is usually carried out exclusive of the former we propose that the spatial distribution of known mineral deposits of the type sought is the key to link mapping of mineral prospectivity and assessment of undiscovered deposits we demonstrate this proposition in regional scale mapping of prospectivity for volcanogenic massive sulphides vms deposits and estimation of undiscovered vms endowment in the skellefte district sweden the results of analyses of the spatial distribution of known vms deposits and their spatial associations with geological features are consistent with existing knowledge of geological controls on vms mineralization in the district and we used them to define spatial recognition criteria of regional scale vms prospectivity integration of layers of evidence representing spatial recognition criteria of vms prospectivity via application of data driven evidential belief functions results in a regional scale map of prospective areas occupying 15 of the district and having fitting and prediction rates of 100 we used the map of prospective areas and proxy measures for degrees of exploration based on the spatial distribution of known vms deposits in one level prediction of undiscovered mineral endowment we obtained estimates of 709 kt undiscovered cu endowment 3190 kt undiscovered zn endowment 95 mt undiscovered ore tonnage and 48 undiscovered vms deposits these estimates are slightly ca 5 on average lower than and thus corroborated by estimates obtained via radial density fractal analysis of the spatial distribution of known vms deposits therefore mineral prospectivity mapping can be a part of mineral resource assessment if the spatial distribution of discovered deposits of the type sought is considered in both predictive modeling processes

making it and breaking it in the midwest continental assembly and rifting from modeling of earthscope magnetotelluric data abstract a three dimensional lithospheric scale resistivity model of the north american mid continent has been estimated based upon earthscope magnetotelluric data details of the resistivity model are discussed in relation to lithospheric sutures defined primarily from aeromagnetic and geochronologic data which record the southward growth of the laurentian margin in the proterozoic the resistivity signature of the 1 1 ga mid continent rift system is examined in detail in particular as relates to rift geometry extent and segmentation an unrecognized expanse of concealed proterozoic deltaic deposits in kansas is identified and speculated to result from axial drainage along the southwest rift arm akin to the rio grande delta which drains multiple rift basins a prominent conductor traces out cambrian rifting in arkansas missouri tennessee and kentucky this linear conductor has not been imaged before and suggests that the cambrian rift system may have been more extensive than previously thought the highest conductivity within the mid continent is imaged in minnesota michigan and wisconsin where it is coincident with paleoproterozoic metasedimentary rocks the high conductivity is attributed to metallic sulfides and in some cases graphite the former is a potential source of sulfur for multiple mineral deposits types occurrences of which are found throughout the region finally the imprint left within the mantle following the 1 1 ga rifting event is examined variations in lithospheric mantle conductivity are observed and are interpreted to reflect variations in water content depleted versus metasomatized mantle imprinted upon the mantle by the keweenawan mantle plume

tightening the siberian connection to western laurentia newly available geological and geophysical data tighten the proterozoic connection between the rifted margins of the northern siberian craton and western laurentia and permit a siberia laurentia australia troika with northern australia connected to the southern margin of the siberian craton the continental assembly is linked by a prominent 2 0 1 8 ga collisional belt and the ca 1 3 1 0 ga grenville orogen the reconstruction also aligns a 1 5 1 45 ga dike sill swarm that extends from the wyoming province through the belt purcell basin into the northern siberian craton separation of australia and siberia may have occurred by the early neoproterozoic but separation of siberia and laurentia may not have been completed until the early cambrian continental extension began along the zigzag siberia laurentia rift zone in the early mesoproterozoic rift related igneous and sedimentary assemblages dated at ca 1 5 1 38 and 1 2 to 1 0 ga correlate across the reconstructed siberia laurentia rift zone renewed rifting in the neoproterozoic and vendian culminated with seafloor spreading and thermal subsidence of the conjugate rift shoulders correlative archeocyathan reefs endemic olenellid trilobite fauna and exchange of detritus between the cratons imply that the rift may have remained relatively narrow until the atdabanian stage black sulfidic shales buried the archeocyathan reefs on the rapidly subsiding rift margins during the botomian sinsk event

genesis of native copper lodes in the keweenaw district northern michigan a hybrid evolved meteoric and metamophogenic model the keweenaw peninsula of northern michigan is well known for early diagenetic sulfide dominant sediment hosted stratiform copper mineralization hosted mainly by basal siltstone shale units of the nonesuch formation in the white pine district and later native copper lodes hosted mainly by flow top breccias and amygdaloidal portions of flood basalts and interbedded conglomerates of the stratigraphically lower portage lake volcanics the native copper mineralization is generally attributed to downdip burial metamorphism of the host strata an alternative model is proposed here involving a complementary influx of evolved meteoric water elevated in salinity and progressively equilibrating with its aquifers similar to the fluid which formed the white pine mineralization this model has several advantages over the metamorphogenic model alone it would provide the salinity by dissolution of evaporites and moderately oxidizing conditions as a result of hematitization i e reddening of coarse continental rift sediments necessary for copper transport and the evolved meteoric water would have been an important cupriferous brine owing to the leaching of trace amounts of copper from the voluminous aquifers further reduction of the evolved fluid would also explain the updip deposition of native copper in association with dehematitized pumpellyite and chlorite dominant i e reduced hydrothermal mineral assemblages at the same time this influx of meteoric water from highlands adjacent to the keweenaw rift basin would have provided a mechanism to move the deep seated hot dense ore brine upward along the aquifers of the portage lake volcanics on its ascent from deep portions of the rift basin the gravity driven evolved meteoric brine would have mixed with the fluid generated by burial metamorphism to form a hybrid evolved meteoric metamorphogenic oreforming hydrothermal brine

landslide susceptibility mapping of vicinity of yaka landslide gelendost turkey using conditional probability approach in gis on 19 february 2007 a landslide occurred on the alaardic slope located 1 6 km south of the town of yaka gelendost turkey subsequently the displaced materials transformed into a mud flow in eglence creek and continued 750 m downstream towards the town of yaka the mass poised for motion in the yaka landslide source area and its vicinity which would be triggered to a kinetic state by trigger factors such as heavy or sustained rainfall and or snowmelt poise a danger in the form of loss of life and property to yaka with its population of 3 000 this study was undertaken to construct a susceptibility mapping of the vicinity of the yaka landslide s source area and to relate it to movement of the landslide mass with the goal of prevention or mitigation of loss of life and property the landslide susceptibility map was formulated by designating the relationship of the effecting factors that cause landslides such as lithology gradient slope aspect elevation topographical moisture index and stream power index to the landslide map as determined by analysis of the terrain through the implementation of the conditional probability method it was determined that the surface area of the goksogut formation which has attained lithological characteristics of clayey limestone with a broken and separated base and where area landslides occur possesses an elevation of 1 100 1 300 m a slope gradient of 15 35 and a slope aspect between 0 67 5 and 157 247 loss of life and property may be avoided by the construction of structures to check the debris mass in eglence creek the cleaning of the canal which passes through yaka the broadening of the canal s base area elevating the protective edges along the canal and the establishment of a protective zone at least 10 m wide on each side of the canal to deter against damage from probable landslide occurrence and mud flow

proterozoic reactivation of the southern superior province and its role in the evolution of the midcontinent rift major reverse faults associated with the late compressional phase of the 1 1 ga midcontinent rift in the western lake superior region appear to cut across the rift at the eastern end of the lake and join with reverse faults on the eastern shoreline defined on the basis of geological and potential field data the continuation of the faults across eastern lake superior is inferred on evidence drawn from nearshore shipborne magnetic surveys together with new interpretations of published bathymetric and glimpce aeromagnetic data in the archean superior province about 100 km east of lake superior paleomagnetic and petrographic data from the 2 45 ga matachewan dyke swarm show that the kapuskasing zone a narrow belt of uplifted crust can be extended to within 50 km of the lake superior shoreline and has bounding reverse faults that are almost continuous with two faults of similar dip and sense of displacement that define the inversion of the midcontinent rift in the central and western parts of the lake si

post rift deformation of the midcontinent rift under grenville tectonism abstract using a thin viscous sheet model we investigate the hypothesis that compressive stresses resulting from the grenville orogeny caused uplift along the midcontinent rift the objective of this study is to investigate factors involved in shaping the post rift structure of the midcontinent rift including the size and location of the colliding terranes and the convergence angle between the colliding terranes and the north american craton we find a linear relationship between the size of the terrane and the deformation within the midcontinent rift the calculations predict comparable deformation along both the eastern and western arms of the midcontinent rift our results demonstrate that the geologically indicated ne sw deformation can be produced without a multistage compression event because of the nonlinear interaction of far field compressive stress and the mechanically weak rift therefore it is not possible to determine which compression direction is representative of the compression associated with the grenvillian orogenic event based on the post rift pattern of deformation

gis based logistic regression for landslide susceptibility mapping of the zhongxian segment in the three gorges area china abstract a detailed landslide susceptibility map was produced using a logistic regression method with datasets developed for a geographic information system gis known as one of the most landslide prone areas in china the zhongxian shizhu segment in the three gorges reservoir region of china was selected as a suitable case to evaluate the frequency and distribution of landslides the site covered an area of 260 9 km 2 with a landslide area of 5 3 km 2 four data domains were used in this study remote sensing products thematic maps geological maps and topographical maps all with 25 25 m 2 pixels or cells statistical relationships for landslide susceptibility were developed using landslide and landslide causative factor databases we extended the application of logistic regression approaches to use all continuous variables as they are and the landslide density is used to transform these nominal variables to numeric variable according to the map 2 8 of the study area was identified as an area with very high susceptibility whereas very low low medium and high susceptibility zones covered 18 2 36 2 26 7 and 16 1 of the area respectively the quality of susceptibility mapping was validated and the correct classification percentage and root mean square error rmse values for the validation data were 81 4 and 0 392 respectively

application of data driven evidential belief functions to landslide susceptibility mapping in jinbu korea abstract evidential belief function ebf model was applied and validated for analysis of landslide susceptibility in the pyungchang area of korea using geographic information system areas of landslide occurrence in the study area were determined from the interpretation of aerial photographs and subsequent field surveys landslide locations were randomly allocated for landslide susceptibility map generation 70 and validation 30 purposes maps relevant to landslide occurrence topography geology soil and forest cover were assembled in a spatial database from which 17 landslide related factors were extracted the relationships between the observed landslide locations and these factors were identified and quantified using the ebf model three relationships were calculated disbelief dis uncertainty unc and belief bel the quantified relationships between each factor and landslide locations of each factor with known landslides were then used as factor ratings in an overlay analysis to create landslide susceptibility indices and maps the most representative of the resulting susceptibility maps the bel map was validated using the landslide data reserved for validation the landslide susceptibility map demonstrates 85 96 accuracy thus the ebf model was found to be effective in terms of prediction accuracy

geochemical controls on leaching of lignite fired combustion by products from greece abstract the mobility of inorganic pollutants is of key concern for a range of industrial and engineering applications of fly ash produced during the combustion of lignite in power generation this paper investigates the role that the geochemical features of lignite the ash composition and the partitioning of elements during combustion play in determining leaching properties of lignite fired by products the work is based on surveys on three lignite fired power plants in greece calcium rich ashes show a high abatement potential for so 2 and other gaseous pollutants for most elements the concentrations in the parent lignite and the ashes follow the same trend relative enrichments in cd co cr cu mo ni pb u v w zn fingerprint the regional and local geological settings of the lignite basins the total and leachable concentrations of highly volatile elements are strongly influenced by the interaction with ubiquitous free lime a broad array of elements is highly insoluble in alkaline ash while a few oxyanionic forming elements display substantial mobility their mode of occurrence in the parent lignite plays a primary role in the leaching of combustion ashes the outcomes of this study may assist in addressing the impact of co firing high ash or high ca alternative fuels on the leaching properties of combustion by products

gis based weights of evidence modelling of rainfall induced landslides in small catchments for landslide susceptibility mapping landslide susceptibility mapping is a vital tool for disaster management and planning development activ ities in mountainous terrains of tropical and subtropical environments in this paper the weights of evidence modelling was applied within a geographical information system gis to derive landslide susceptibility map of two small catchments of shikoku japan the objective of this paper is to evaluate the importance of weights of evidence modelling in the generation of landslide susceptibility maps in relatively small catchments having an area less than 4 sq km for the study area in moriyuki and monnyu catchments northeast shikoku island in west japan a data set was generated at scale 1 5 000 relevant thematic maps representing various factors e g slope aspect relief flow accumulation soil depth soil type land use and distance to road that are related to landslide activity were generated using field data and gis techniques both catchments have homogeneous geology and only consist of cretaceous granitic rock thus bedrock geology was not considered in data layering during gis analysis success rates were also estimated to evaluate the accuracy of landslide suscepti bility maps and the weights of evidence modelling was found useful in landslide susceptibility mapping of small catchments

geochemistry of north shore hypabyssal dikes and sills in the midcontinent rift of minnesota an example the 47th avenue sill this study presents geochemical data for several of the numerous small to large dikes and sills including the 47th avenue sill exposed along the shore of lake superior in and north of duluth minnesota these intrusions are late magmatic features of the proterozoic midcontinent rift system and together form the north shore hypabyssal group the dikes are geochemically distinct from the sills and when the two are exposed together the younger dike intrudes the older sill dikes are primitive with mg up to 68 have positive end values and are oriented approximately north south with steep westerly or near vertical dips the older sills are more evolved usually have end values near or below 0 and have the same gentle easterly dip as the thick sequence of north shore volcanic group flows they intrude dike compositions correlate best with a mixture of widespread basalt compositions types 4 and 5 with primitive geochemistry and positive end values whereas sill compositions are similar to widespread ba

gis based landslide susceptibility mapping using analytical hierarchy process and bivariate statistics in ardesen turkey comparisons of results and confirmations abstract the ardesen area is prone to landslides because of the climate conditions geologic and geomorphologic characteristics of the region as in previous years in 2001 due to heavy rainfall there were many landslides resulting in damage and human casualties there is still a great danger of further landslides in the region therefore it is vitally important to prepare a landslide susceptibility map of the region in this study the analytical hierarchy process ahp the statistical index wi and weighting factor wf methods were used to produce and later compare three susceptibility maps for this purpose thematic layers including landslide inventory lithology weathering slope aspect land cover distance to stream drainage density and distance to road were used in this study area 98 of landslides occurred in highly or completely weathered units lithology weathering land cover and slope data layers were found to be important factors in the study area to confirm the practicality of the three susceptibility maps were compared with a landslide activity map containing 16 active landslide zones the outcome was that the active landslide zones do not completely fit into the high and very high susceptibility classes but 81 3 of these landslide zones fall into the high and very high susceptibility zones of the ahp method while this is 62 5 in the case of wi method and 68 8 with the wf method in spite of the results obtained in this study the development of a susceptibility map is usually determined by the needs and available resources the results showed that the ahp method gave a more realistic picture of the actual distribution of landslide susceptibility than the wi and wf methods

a gis based landslide susceptibility evaluation using bivariate and multivariate statistical analyses bivariate and multivariate statistical analyses were used to predict the spatial distribution of landslides in the cuyahoga river watershed northeastern ohio u s a the relationship between landslides and various instability factors contributing to their occurrence was evaluated using a geographic information system gis based investigation a landslide inventory map was prepared using landslide locations identified from aerial photographs field checks and existing literature instability factors such as slope angle soil type soil erodibility soil liquidity index landcover pattern precipitation and proximity to stream responsible for the occurrence of landslides were imported as raster data layers in arcgis and ranked using a numerical scale corresponding to the physical conditions of the region in order to investigate the role of each instability factor in controlling the spatial distribution of landslides both bivariate and multivariate models were used to analyze the digital dataset the logistic regression approach was used in the multivariate model analysis both models helped produce landslide susceptibility maps and the suitability of each model was evaluated by the area under the curve method and by comparing the maps with the known landslide locations the multivariate logistic regression model was found to be the better model in predicting landslide susceptibility of this area the logistic regression model produced a landslide susceptibility map at a scale of 1 24 000 that classified susceptibility into four categories low moderate high and very high the results also indicated that slope angle proximity to stream soil erodibility and soil type were statistically significant in controlling the slope movement

landslide susceptibility maps comparing frequency ratio and artificial neural networks a case study from the nepal himalaya this study considers landslide susceptibility mapping by means of frequency ratio and artificial neural network approaches using geographic information system gis techniques as a basic analysis tool the selected study area was that of the panchthar district nepal gis was used for the management and manipulation of spatial data landslide locations were identified from field survey and aerial photographic interpretation was used for location of lineaments ten factors in total are related to the occurrence of landslides based on the same set of factors landslide susceptibility maps were produced from frequency ratio and neural network models and were then compared and evaluated the weights of each factor were determined using the back propagation training method landslide susceptibility maps were produced from frequency ratio and neural network models and they were then compared by means of their checking the landslide location data were used for checking the results with the landslide susceptibility maps the accuracy of the landslide susceptibility maps produced by the frequency ratio and neural networks is 82 21 and 78 25 respectively

the mesoproterozoic midcontinent rift system lake superior region usa abstract exposures in the lake superior region and associated geophysical evidence show that a 2000 km long rift system developed within the north american craton 1109 1087 ma the age span of most of the volcanic rocks this system is characterized by immense volumes of mafic igneous rocks mostly subaerial plateau basalts generated in two major pulses largely by a hot mantle plume a new ocean basin was nearly formed before rifting ceased perhaps due to the remote effect of the grenville continental collision to the east broad sagging subsidence combined with a system of axial half grabens separated along the length of the rift by accommodation zones provided conditions for the accumulation of as much as 20 km of volcanic rocks and as much as 10 km of post rift clastic sediments both along the rift axis and in basins flanking a central post volcanic horst pre rift mature quartzose sandstones imply little or no uplift prior to the onset of rift volcanism early post rift red bed sediments consist almost entirely of intrabasinally derived volcanic sediment deposited in alluvial fan to fluvial settings the exception is one gray to black carbon bearing lacustrine unit this early sedimentation phase was followed by broad crustal sagging and deposition of progressively more mature red bed fluvial sediments with an extra basinal provenance

predictive mapping of prospectivity for orogenic gold giyani greenstone belt south africa we present a mineral systems approach to predictive mapping of orogenic gold prospectivity in the giyani greenstone belt ggb by using layers of spatial evidence representing district scale processes that are critical to orogenic gold mineralization namely a source of metals fluids b active pathways c drivers of fluid flow and d metal deposition to demonstrate that the quality of a predictive map of mineral prospectivity is a function of the quality of the maps used as sources of spatial evidence we created two sets of prospectivity maps one using an old lithologic map and another using an updated lithological map as two separate sources of spatial evidence for source of metals fluids drivers of fluid flow and metal deposition we also demonstrate the importance of using spatially coherent or geologically consistent deposit occurrences in data driven predictive mapping of mineral prospectivity the best predictive orogenic gold prospectivity map obtained in this study is the one that made use of spatial evidence from the updated lithological map and spatially coherent orogenic gold occurrences this map predicts 20 of the ggb to be prospective for orogenic gold with 89 goodness of fit between spatially coherent inactive orogenic gold mines and individual layers of spatial evidence and 89 prediction rate against spatially coherent orogenic gold prospects in comparison the predictive gold prospectivity map obtained by using spatial evidence from the old lithological map and all gold occurrences has 80 goodness of fit but only 63 prediction rate these results mean that the prospectivity map based on spatially coherent gold occurrences and spatial evidence from the updated lithological map predicts exploration targets better i e 28 smaller prospective areas with 9 stronger fit to training gold mines and 26 higher prediction rate with respect to validation gold prospects than the prospectivity map based on all known gold occurrences and spatial evidence from the old lithological map

paleomagnetism of the native copper mineralization keweenaw peninsula michigan the age and genesis of michigan s world class native copper deposits are poorly constrained the copper is hosted by basaltic flow tops and conglomeratic interbeds of the 1095 2 ma keweenawan por

landslide susceptibility assessment in lianhua county china a comparison between a random forest data mining technique and bivariate and multivariate statistical models abstract landslides are an important natural hazard that causes a great amount of damage around the world every year especially during the rainy season the lianhua area is located in the middle of china s southern mountainous area west of jiangxi province and is known to be an area prone to landslides the aim of this study was to evaluate and compare landslide susceptibility maps produced using the random forest rf data mining technique with those produced by bivariate evidential belief function and frequency ratio and multivariate logistic regression statistical models for lianhua county china first a landslide inventory map was prepared using aerial photograph interpretation satellite images and extensive field surveys in total 163 landslide events were recognized in the study area with 114 landslides 70 used for training and 49 landslides 30 used for validation next the landslide conditioning factors including the slope angle altitude slope aspect topographic wetness index twi slope length ls plan curvature profile curvature distance to rivers distance to faults distance to roads annual precipitation land use normalized difference vegetation index ndvi and lithology were derived from the spatial database finally the landslide susceptibility maps of lianhua county were generated in arcgis 10 1 based on the random forest rf evidential belief function ebf frequency ratio fr and logistic regression lr approaches and were validated using a receiver operating characteristic roc curve the roc plot assessment results showed that for landslide susceptibility maps produced using the ebf fr lr and rf models the area under the curve auc values were 0 8122 0 8134 0 7751 and 0 7172 respectively therefore we can conclude that all four models have an auc of more than 0 70 and can be used in landslide susceptibility mapping in the study area meanwhile the ebf and fr models had the best performance for lianhua county china thus the resultant susceptibility maps will be useful for land use planning and hazard mitigation aims

segregation of magmatic fluids and their potential in the mobilization of platinum group elements in the south kawishiwi intrusion duluth complex minnesota evidence from petrography apatite geochemistry and coexisting fluid and melt inclusions abstract pegmatitic and other felsic rock pockets and dike like intrusions are abundant in the south kawishiwi intrusion of the duluth complex including the basal cu ni pge mineralized units these occurrences are found as pockets pods or as veins and contain abundant accessory apatite and quartz quartz hosts primary fluid inclusions as well as silicate melt inclusions combined microthermometry and raman spectroscopy helped to determine the bulk composition of primary fluid inclusions that are co 2 rich 95 mol and contain small amounts of h 2 o 4 5 mol ch 4 0 4 mol and trace n 2 respectively this combined technique also made it possible to measure total homogenization temperatures of the inclusions th tot 225 10 c otherwise not detectable during microthermometry silicate melt inclusions have been quenched to produce homogeneous glasses corresponding to the original melt composition of the entrapped melt is granitoid peraluminous and is very poor in mafic components we interpret the melt as a product of partial melting of the footwall rocks due to the contact effect of the south kawishiwi intrusion the presence of co 2 in the vapor bubbles of the quenched melt inclusions and petrographic evidence suggest that the fluid and melt inclusion assemblages are coeval the composition of the fluid and melt phase implies that the fluid originates from the mafic magma of the south kawishiwi intrusion and the fluid and melt phases coexisted as a heterogeneous melt fluid system until entrapment of the inclusions coexistence of primary fluid and melt inclusions makes it possible to calculate a minimum entrapment pressure 1 7 kbar and thus estimate formation depth 5 8 km for the inclusions chlorine is suggested to behave compatibly in the silicate melt phase in the fluid melt system represented by the inclusions indicated by the high up to 0 3 cl concentrations of the silicate melt and co 2 rich nature of the fluid apatite halogen contents provide further details on the behavior of cl apatite in pegmatitic pockets often has elevated cl concentrations compared to troctolitic rocks suggesting enrichment of cl with progressive crystallization systematic trends of cl loss at some differentiated melt pockets suggest that in some places cl exsolved into a fluid phase and migrated away from its source the segregation of cl from the melt is probably inhibited by the presence of co 2 rich fluids until the last stages of crystallization increasing the potential for the development of late stage saline brines platinum group minerals are often present in microcracks in silicate minerals in late stage differentiated sulfide veinlets and in association with chlorapatite indicating the potential role of cl bearing fluids in the final distribution of pges

a gis based comparative study of frequency ratio analytical hierarchy process bivariate statistics and logistics regression methods for landslide susceptibility mapping in trabzon ne turkey abstract over the last few decades many researchers have produced landslide susceptibility maps using different techniques including the probability method frequency ratio the analytical hierarchy process ahp bivariate multivariate logistics regression fuzzy logic and artificial neural network in addition a number of parameters such as lithology slope aspect land cover elevation distance to stream drainage density distance to lineament seismicity and distance to road are recommended to analyze the mechanism of landslides the data quality is a very important issue in landslide studies and more accurate results will be achieved if the data is adequate appropriate and drawn from a wide range of parameters the aim of this study was to evaluate the susceptibility of the occurrence of landslides in trabzon province situated in north east turkey this was achieved using the following five methods the frequency ratio model ahp the statistical index wi weighting factor wf methods and the logistics regression model incorporating a geographical information system gis and remote sensing techniques in trabzon province there has been an increasing occurrence of landslides triggered by rainfall these landslides have resulted in death significant injury damage to property and local infrastructure and threat of further landslides continues in order to reduce the effects of this phenomenon it is necessary to scientifically assess the area susceptible to landslide to achieve this landslide susceptible areas were mapped the landslide occurrence parameters were analyzed using five different methods the results of the five analyses were confirmed using the landslide activity map containing 50 active landslide zones then the methods giving more accurate results were determined the validation process showed that the wf method is better in prediction than the frequency ratio model ahp the statistical index wi and logistics regression model

predictive landslide susceptibility mapping using spatial information in the pechabun area of thailand for predictive landslide susceptibility mapping this study applied and verified probability model the frequency ratio and statistical model logistic regression at pechabun thailand using a geographic information system gis and remote sensing landslide locations were identified in the study area from interpretation of aerial photographs and field surveys and maps of the topography geology and land cover were constructed to spatial database the factors that influence landslide occurrence such as slope gradient slope aspect and curvature of topography and distance from drainage were calculated from the topographic database lithology and distance from fault were extracted and calculated from the geology database land cover was classified from landsat tm satellite image the frequency ratio and logistic regression coefficient were overlaid for landslide susceptibility mapping as each factor s ratings then the landslide susceptibility map was verified and compared using the existing landslide location as the verification results the frequency ratio model showed 76 39 and logistic regression model showed 70 42 in prediction accuracy the method can be used to reduce hazards associated with landslides and to plan land cover

assessment of landslide susceptibility using gis based evidential belief function in patu khola watershed dang nepal patu khola watershed lies in dang valley of west nepal the rocks belonging to the precambrian lesser himalaya and the miocene siwalik cover the northern portion of the watershed while the southern flat area is covered by the quaternary river terraces the basin is disrupted by two regional scale thrusts bhotechaur thrust and kapurkot thrust and several imbricate faults making it prone to instabilities the river valley is heavily populated as the growing population has forced the people to dwell in such risky zone thus it is very essential to develop a landslide hazard map of this basin in this respect we have used an evidential belief function ebf model in the gis environment to know different landslide susceptible zones in the watershed for this a landslide inventory map consisting of 279 different types of landslides was generated from the published topographic maps aerial photograph and google earth image interpretations and from the detailed filed survey from the mapped landslides 80 were randomly selected for developing the model and the remaining 20 were used for validating the model twelve different landslide causative factors were considered for this study thus from the analysis of the landslide data and factor maps a susceptibility map of the region was obtained by using the ebf model the map was evaluated using area under the curve auc of success and prediction rate the verification result showed that the model performed very well with the success rate of 85 13 and predictive accuracy is 86 42 the produced susceptibility map can be useful for general land use planning as well as it can provide information to the planners for the adaptation of appropriate mitigating measures for landside hazards in the patu khola watershed

comment on paleozoic reactivation structures in the appalachian ouachita marathon foreland far field deformation across pangea by j craddock d malone r porter j compton j luczaj a konstantinou j day and s johnston earth science reviews 169 2017 1 34

closing of the midcontinent rift a far field effect of grenvillian compression the midcontinent rift formed in the laurentian supercontinent between 1109 and 1094 ma soon after rifting stresses changed from extensional to compressional and the central graben of the rift was partly inverted by thrusting on original extensional faults thrusting culminated at about 1060 ma but may have begun as early as 1080 ma on the southwest trending arm of the rift the crust was shortened about 30 km on the southeast trending arm strike slip motion was dominant the rift developed adjacent to the tectonically active grenville province and its rapid evolution from an extensional to a compressional feature at ca 1080 ma was coincident with renewal of northwest directed thrusting in the grenvllle probably caused by continent continent collision a zone of weak lithosphere created by rifting became the locus for deformation within the otherwise strong continental lithosphere stresses transmitted from the grenville province utilized this weak zone to close and invert the rift

transect across the northwestern grenville orogen georgian bay ontario polystage convergence and extension in the lower orogenic crust the grenville orogenic cycle between 1190 and 980 ma involved accretion of magmatic arcs and or continental terranes to the laurentian craton a transect across the western central gneiss belt georgian bay ontario which crosses the boundary between parautochthonous and allochthonous units at an inferred orogenic depth of 20 30 km offers some insights on the thermal and mechanical behavior of the lower crust during the development of the grenville orogen prior to grenvillian metamorphism this part of laurentia consisted largely of meso proterozoic 1450 ma granitoid orthogneisses granulites and subordinate mafic and supracrustal rocks grenvillian convergence along the transect began with transport of the previously deformed and metamorphosed 1160 ma parry sound domain over the craton sometime between 1120 ma and 1080 ma this stage of transport was followed by out of sequence thrusting and further convergence along successively deeper foreland propagating ductile thrust zones a major episode of extension at 1020 ma resulted in southeast directed transport of allochthonous rocks along the midcrustal shawanaga shear zone the final stage of convergence involved deformation and metamorphism in the grenville front tectonic zone at 1000 980 ma peak metamorphism along most of the transect at 1065 1045 ma followed initial transport of allochthonous rocks over the craton by 15 35 m y regional cooling which postdated peak metamorphism by 70 m y was probably delayed by the combined effects of late stage extension and convergence transport of allochthons at least 100 km over the craton was accomplished along a weak migmatitic decollement further propagation of the orogen into the craton followed partial melting and weakening of parautochthonous rocks below this decollement extensional deformation was associated with distributed ductile flow the formation of regional transverse folds with axes parallel to the stretching direction and reactivation of the allochthon parautochthon thrust boundary as an extensional decollement the extensional lower crustal flow was likely the primary cause of the subhorizontal attitude of many structures and seismic reflectors in this part of the central gneiss belt

the susceptibility of oklahoma s basement to seismic reactivation recent widespread seismicity in oklahoma is attributed to the reactivation of pre existing critically stressed and seismically unstable faults due to decades of wastewater injection however the structure and properties of the reactivated faults remain concealed by the sedimentary cover here we explore the major ingredients needed to induce earthquakes in oklahoma by characterizing basement faults in the field in seismic surveys and via rock mechanics experiments outcrop and satellite mapping reveal widespread fault and fracture systems with trends that display a marked similarity to the trends of recent earthquake lineaments our three dimensional seismic analyses show steeply dipping basement rooted faults that penetrate the overlying sedimentary sequences representing pathways for wastewater migration experimental stability analysis indicates that oklahoma s basement rocks become seismically unstable at conditions relevant to the dominant hypocentral depths of the recent earthquakes these analyses demonstrate that the geometry structure and mechanical stability of oklahoma s basement make it critically susceptible to seismic reactivation seismicity induced by wastewater injections is widespread in oklahoma probably because its basement is susceptible to the reactivation of basement rooted faults according to three dimensional seismic analyses rock mechanics experiments and field surveys

using maximum entropy modeling for landslide susceptibility mapping with multiple geoenvironmental data sets the potential of using maximum entropy modeling for landslide susceptibility mapping is investigated in this paper although the maximum entropy model has been applied widely to species distribution modeling in ecology its applicability to other kinds of predictive modeling such as landslide susceptibility mapping has not yet been investigated fully in the present case study of boeun in korea multiple environmental factors including continuous and categorical data were used as inputs for maximum entropy modeling from the optimal setting test based on cross validation the effective feature type for continuous data representation was found to be a hinge feature and its combination with categorical data showed the best predictive performance factor contribution analysis indicated that distances from lineaments and slope layers were the most influential factors from interpretations on a response curve steeply sloping and weathered areas that consisted of excessively drained granite residuum soils were very susceptible to landslides predictive performance of maximum entropy modeling was slightly better than that of a logistic regression model which has been used widely to assess landslide susceptibility therefore maximum entropy modeling is shown to be an effective prediction model for landslide susceptibility mapping

gis based landslide susceptibility for arsin yomra trabzon north turkey region the purpose of this study is to assess the susceptibility of landslides around yomra and arsin towns near trabzon in northeast of turkey using a geographical information system gis landslide inventory of the area was made by detailed field surveys and the analyses of the topographical map the landslide triggering factors are considered to be slope angle slope aspect distance from drainage distance from roads and the weathered lithological units which were called as geotechnical units in the study idrisi and arcgis packages manipulated all the collected data logistic regression lr and weighted linear combination wlc statistical methods were used to create a landslide susceptibility map for the study area the results were assessed within the scope of two different points a effectiveness of the methods used and b effectiveness of the environmental casual parameters influencing the landslides the results showed that the wlc model is more suitable than the lr model regarding the casual parameters geotechnical units and slopes were found to be the most important variables for estimating the landslide susceptibility in the study area

delineation of landslide hazard areas on penang island malaysia by using frequency ratio logistic regression and artificial neural network models this paper summarizes findings of landslide hazard analysis on penang island malaysia using frequency ratio logistic regression and artificial neural network models with the aid of gis tools and remote sensing data landslide locations were identified and an inventory map was constructed by trained geomorphologists using photo interpretation from archived aerial photographs supported by field surveys a spot 5 satellite pan sharpened image acquired in january 2005 was used for land cover classification supported by a topographic map the above digitally processed images were subsequently combined in a gis with ancillary data for example topographical slope aspect curvature drainage geological litho types and lineaments soil types and normalized difference vegetation index ndvi data and used to construct a spatial database using gis and image processing three landslide hazard maps were constructed on the basis of landslide inventories and thematic layers using frequency ratio logistic regression and artificial neural network models further each thematic layer s weight was determined by the back propagation training method and landslide hazard indices were calculated using the trained back propagation weights the results of the analysis were verified and compared using the landslide location data and the accuracy observed was 86 41 89 59 and 83 55 for frequency ratio logistic regression and artificial neural network models respectively on the basis of the higher percentages of landslide bodies predicted in very highly hazardous and highly hazardous zones the results obtained by use of the logistic regression model were slightly more accurate than those from the other models used for landslide hazard analysis the results from the neural network model suggest the effect of topographic slope is the highest and most important factor with weightage value 1 0 which is more than twice that of the other factors followed by the ndvi 0 52 and then precipitation 0 42 further the results revealed that distance from lineament has the lowest weightage with a value of 0 this shows that in the study area fault lines and structural features do not contribute much to landslide triggering

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

mantle temperature and lithospheric thinning beneath the midcontinent rift system evidence from magmatism and subsidence the tectono magmatic history of the midcontinent rift system can be explained by the presence of a mantle plume bringing elevated temperature mantle beneath the rift system at about 1110 ma huge volumes of extrusive and intrusive igneous rocks were generated as abnormally hot mantle decompressed beneath the lithospheric rift geochemical and isotopic data from the keweenawan volcanics show that the earliest melts were derived from small degree melting of primitive plume mantle coupled with enriched metasomatic melts derived from the continental lithosphere as rifting progressed the main bulk of the volcanics was generated primarily from the plume mantle with the melting starting at depths of about 120 km and extending to as shallow as the base of the stretched lithosphere at 45 km depth elevated mantle temperatures of 1500 1560 c approximately 150 200 c above normal are inferred from the rare earth element concentrations in the volcanic rocks further constraints on the mantle temperature come f

geologic transect across the grenville orogen of ontario and new york revised cross sections of the western grenville province incorporate new geologic results and reprocessed seismic reflection data the geology is presented in terms of three tectonic elements 1 pre grenvillian laurentia and its margin with ca 1740 and 1450 ma continental arc plutons and associated supracrustal rocks 2 composite arc belt of allochthonous 1300 1250 ma volcanic arcs and sedimentary rocks and 3 frontenac adirondack belt characterized by supracrustal and granitoid rocks and anorthosites of uncertain affinity that may represent a distinctive part of the composite arc belt or an offshore micro continent rocks of the composite arc and frontenac adirondack belts were amalgamated with each other by ca 1160 ma were then thrust over laurentia during ca 1080 1035 ma and ca 1010 980 ma phases of convergence and were dissected and exhumed by 1040 ma normal faults penetrative deformation was restricted to that part of the pre grenvillian laurentian margin that lies to the southeast of the grenville front and parts of the accreted composite arc and frontenac adirondack belts the laurentian rocks in the grenville province are bounded to the northwest and southeast by southeast dipping ductile thrust and or normal shear zones the composite arc and frontenac adirondack belts to the southeast are bounded by ductile and brittle ductile thrust and or normal faults that separate domains with contrasting cooling histories despite a long pre grenvillian tectonic and plutonic history the present crustal architecture and much of the seismic reflectivity were acquired during 1080 980 ma phases of compression and extension

three dimensional electrical resistivity of the north central usa from earthscope long period magnetotelluric data abstract we present initial results from three dimensional inversion of long period earthscope magnetotelluric mt transportable array data from 232 sites covering the north central us the study area covers the 1 1 ga mid continent rift mcr system which cuts across a series of archean and paleoproterozoic lithospheric blocks the western arm of the mcr is clearly evident in shallow depth sections with a narrow resistive core flanked by elongate conductive basins other prominent upper crustal features mapped include the moderately conductive michigan and illinois basins and extremely high conductivities in foreland basin rocks at the southern margin of the superior craton the most prominent conductive anomalies in an otherwise relatively resistive mid lower crust are two elongate east west oriented structures which are closely aligned with previously inferred continental sutures the first underlies the southern margin of the superior craton just north of the niagara fault nf and can be associated with the 1 85 ga penokean orogeny a second further south beneath iowa and western wisconsin lies just south of the spirit lake tectonic zone sltz and can be identified with yavapai accretion at 1 75 ga both of these conductive sutures are cleanly cut by the mcr which is otherwise not clearly evident in the deeper parts of the resistivity model the break in the anomalies is narrow comparable to the surface expression of the mcr indicating that rifting impacts on the entire crustal section were highly localized both suture related anomalies are imaged as extending into and perhaps through the lithosphere as dipping diffuse zones of reduced mantle resistivity sense of dip of these structures southward for the nf anomaly northward for sltz agrees with previously inferred models for subduction and accretion suggesting that a conductive phase most likely carbon has been thrust deep into the lower crust and uppermost mantle providing a marker of the three dimensional boundary between lithospheric blocks resistivities drop below 100 m below 200 km depth in rough agreement with the seismically determined lithosphere asthenosphere boundary lab there are modest lateral variations in this deep low resistivity layer but the reliability and significance of these are not yet clear

the eagle and east eagle sulfide ore bearing mafic ultramafic intrusions in the midcontinent rift system upper michigan geochronology and petrologic evolution 1 the eagle and east eagle intrusions are small subvertical dike like mafic ultramafic bodies that cut proterozoic sedimentary strata in the baraga basin in northern michigan the eagle intrusion hosts a newly discovered magmatic ni cu pge deposit the nearby east eagle intrusion also contains sulfide mineralization but the extent of this mineralization has yet to be determined by further drilling both intrusions contain olivine bearing rocks such as feldspathic peridotite melatroctolite and olivine melagabbro sulfide accumulations range from disseminated at both eagle and east eagle to semimassive and massive at eagle u pb baddeleyite dating gives a crystallization age of 1107 2 5 7 ma for the eagle intrusion coeval with eruption of picritic basalts at the base of the volcanic succession in the midcontinent rift system mrs the fo contents of olivine cores in the eagle and east eagle intrusions vary between 75 and 85 mol higher than those of olivine in larger layered intrusions in the mrs such as the duluth complex the feo mgo ratios and al2o3 contents of the parental magmas for the eagle and east eagle intrusions inferred from olivine and spinel compositions are similar to those of picritic basalts in the base of the mrs volcanic succession these petrochemical data suggest that the eagle and east eagle intrusions are the intrusive equivalents of high mgo basalts that erupted in the early stages of continental magmatism associated with the development of the rift variations in mineral compositions and incompatible trace element ratios suggest that at least three major pulses of magmas were involved in the formation of low sulfide rocks in the eagle intrusion lower fo contents of olivine associated with semimassive sulfides as compared to that of olivine in low sulfide rocks suggest that the magma associated with the semimassive sulfide was more fractionated than the parental magmas of the low sulfide rocks in the eagle intrusion accumulation of suspended olivine crystals and sulfide droplets from ascending magmas as they passed through wide parts of the conduits at eagle and east eagle played a critical role in the genesis of olivine rich rocks and sulfide ores in the intrusions the eagle ni cu pge deposit typifies the conduit style of magmatic sulfide deposition that is associated with continental basaltic magmatism

sevier laramide deformation of the continental interior from calcite twinning analysis west central north america abstract paleozoic mesozoic carbonates that cover cratonic western north america contain a regional layer parallel shortening lps fabric that is preserved by mechanically twinned calcite shortening directions are generally parallel to the sevier thrust transport direction e w in carbonates of the idaho wyoming portion of the thrust belt and within carbonates as far as 2000 km into the plate interior the inferred calcite twinning differential stress magnitudes generally decrease across the thrust belt and decrease exponentially away from the orogenic front into the craton synorogenic calcite cements and veins preserve a distinct twinning deformation history in the thrust belt twinning strains commonly record local out of transport piggyback strain events with high differential stresses

a comparative study of dempster shafer and fuzzy models for landslide susceptibility mapping using a gis an experience from zagros mountains sw iran abstract a catchment area at the zagros mountains nw shiraz iran is selected as a test site to comparing the output results of the dempster shafer d s and fuzzy models in landslide hazard mapping lithology slope angle slope aspect land cover and soil depth were considered as landslide causal factors the factor maps were input into a gis and a modified landslide hazard evaluation factor mlhef rating and fuzzy membership functions as well as belief function values were assessed for each class of the factor maps the fuzzy sum product and gamma combination approaches were examined and output maps were assessed based on the known landslides the outputs of fuzzy sum and product combination rules were not reasonable because these approaches classified the area into very high or very low susceptibility zones respectively which were not compatible to the field and factor maps criteria a value of 0 94 yielded the most reliable susceptibility for landslides overlay of the known landslides with the output favorability map showed that the identified landslides were located in the high and very high susceptible zones the output results of the dempster shafer model plausibility belief and uncertainty images were also evaluated based on the known landslides the results of this approach revealed that although it was expected that most of the known landslides correspond the plausibility or the belief map only a few of them supported the case and some landslides were coincided into the disbelief or uncertainty maps it is concluded that in comparison to the fuzzy model the d s model obtains less reliable results for landslide hazard mapping since the belief functions were assigned based on the fuzzy membership functions this might be due to the integration equations used by the model or the number of evidence maps used as input layers

validation of an artificial neural network model for landslide susceptibility mapping the aim of this study was to validate an artificial neural network model at youngin janghung and boeun korea using the geographic information system gis the factors that influence landslide occurrence such as the slope aspect curvature and geomorphology of topography the type material drainage and effective thickness of soil the type diameter age and density of forest distance from lineament and land cover were either calculated or extracted from the spatial database and landsat tm satellite images landslide susceptibility was analyzed using the landslide occurrence factors provided by the artificial neural network model the landslide susceptibility analysis results were validated and cross validated using the landslide locations as study areas for this purpose weights for each study area were calculated by the artificial neural network model among the nine cases the best accuracy 81 36 was obtained in the case of the boeun based janghung weight whereas the janghung based youngin weight showed the worst accuracy 71 72

determination and application of the weights for landslide susceptibility mapping using an artificial neural network the purpose of this study is the development application and assessment of probability and artificial neural network methods for assessing landslide susceptibility in a chosen study area as the basic analysis tool a geographic information system gis was used for spatial data management and manipulation landslide locations and landslide related factors such as slope curvature soil texture soil drainage effective thickness wood type and wood diameter were used for analyzing landslide susceptibility a probability method was used for calculating the rating of the relative importance of each factor class to landslide occurrence for calculating the weight of the relative importance of each factor to landslide occurrence an artificial neural network method was developed using these methods the landslide susceptibility index lsi was calculated using the rating and weight and a landslide susceptibility map was produced using the index the results of the landslide susceptibility analysis with and without weights were confirmed from comparison with the landslide location data the comparison result with weighting was better than the results without weighting the calculated weight and rating can be used to landslide susceptibility mapping

landslide susceptibility mapping by neuro fuzzy approach in a landslide prone area cameron highlands malaysia this paper presents the results of the neuro fuzzy model using remote sensing data and geographic information system for landslide susceptibility analysis in a part of the cameron highlands areas in malaysia landslide locations in the study area were identified by interpreting aerial photographs and satellite images supported by extensive field surveys landsat tm satellite imagery was used to map the vegetation index maps of the topography lineaments normalized difference vegetation index ndvi and land cover were constructed from the spatial data sets eight landslide conditioning factors such as altitude slope gradient curvature distance from the drainage distance from the road lithology distance from the faults and ndvi were extracted from the spatial database these factors were analyzed using a neuro fuzzy model adaptive neuro fuzzy inference system to produce the landslide susceptibility maps during the model development works a total of five landslide susceptibility models were constructed for verification the results of the analyses were then compared with the field verified landslide locations additionally the receiver operating characteristic curves for all landslide susceptibility models were drawn and the area under curve values were calculated landslide locations were used to validate the results of the landslide susceptibility map and the verification results showed a 97 accuracy for model 5 employing all parameters produced in the present study as the landslide conditioning factors the validation results showed a sufficient agreement between the obtained susceptibility map and the existing data on the landslide areas qualitatively the model yields reasonable results which can be used for preliminary land use planning purposes

a comparative study of sequential minimal optimization based support vector machines vote feature intervals and logistic regression in landslide susceptibility assessment using gis landslide susceptibility assessment using gis has been done for part of uttarakhand region of himalaya india with the objective of comparing the predictive capability of three different machine learning methods namely sequential minimal optimization based support vector machines smosvm vote feature intervals vfi and logistic regression lr for spatial prediction of landslide occurrence out of these three methods the smosvm and vfi are state of the art methods for binary classification problems but have not been applied for landslide prediction whereas the lr is known as a popular method for landslide susceptibility assessment in the study a total of 430 historical landslide polygons and 11 landslide affecting factors such as slope angle slope aspect elevation curvature lithology soil land cover distance to roads distance to rivers distance to lineaments and rainfall were selected for landslide analysis for validation and comparison statistical index based methods and the receiver operating characteristic curve have been used analysis results show that all these models have good performance for landslide spatial prediction but the smosvm model has the highest predictive capability followed by the vfi model and the lr model respectively thus smosvm is a better model for landslide prediction and can be used for landslide susceptibility mapping of landslide prone areas

mapping of prospectivity and estimation of number of undiscovered prospects for lode gold southwestern ashanti belt ghana in the southwestern part of the ashanti belt the results of fractal and fry analyses of the spatial pattern of 51 known mines prospects of mostly lode gold deposits and the results of analysis of their spatial associations with faults and fault intersections suggest different predominant structural controls on lode gold mineralisation at local and district scales intersections of nne and nw trending faults were likely predominantly involved in local scale structural controls on lode gold mineralisation whilst nne trending faults were likely predominantly involved in district scale structural controls on lode gold mineralisation the results of the spatial analyses facilitate the conceptualisation and selection of spatial evidence layers for lode gold prospectivity mapping in the study area the applications of the derived map of lode gold prospectivity and a map of radial density of spatially coherent lode gold mines prospects results in a one level prediction of 37 undiscovered lode gold prospects the applications of quantified radial density fractal dimensions of the spatial pattern of spatially coherent lode gold mines prospects result in an estimate of 40 undiscovered lode gold prospects the study concludes finally that analysis of the spatial pattern of discovered mineral deposits is the key to a strong link between mineral prospectivity mapping and assessment of undiscovered mineral deposits

landslide susceptibility assessment using logistic regression and its comparison with a rock mass classification system along a road section in the northern himalayas india landslide studies are commonly guided by ground knowledge and field measurements of rock strength and slope failure criteria with increasing sophistication of gis based statistical methods however landslide susceptibility studies benefit from the integration of data collected from various sources and methods at different scales this study presents a logistic regression method for landslide susceptibility mapping and verifies the result by comparing it with the geotechnical based slope stability probability classification sspc methodology the study was carried out in a landslide prone national highway road section in the northern himalayas india logistic regression model performance was assessed by the receiver operator characteristics roc curve showing an area under the curve equal to 0 83 field validation of the sspc results showed a correspondence of 72 between the high and very high susceptibility classes with present landslide occurrences a spatial comparison of the two susceptibility maps revealed the significance of the geotechnical based sspc method as 90 of the area classified as high and very high susceptible zones by the logistic regression method corresponds to the high and very high class in the sspc method on the other hand only 34 of the area classified as high and very high by the sspc method falls in the high and very high classes of the logistic regression method the underestimation by the logistic regression method can be attributed to the generalisation made by the statistical methods so that a number of slopes existing in critical equilibrium condition might not be classified as high or very high susceptible zones

evidential belief functions for data driven geologically constrained mapping of gold potential baguio district philippines abstract a data driven application of the theory of evidential belief to map mineral potential is demonstrated with a redefinition of procedures to estimate evidential belief functions the redefined estimates of evidential belief functions take into account not only the spatial relationship of an evidence with the target mineral deposit but also consider the relationships among the subsets of spatial evidences within a set of evidential data layer proximity of geological features to mineral deposits is translated into spatial evidence and evidential belief functions are estimated for the proposition that mineral deposits exist in a test area the integrated maps of degrees of belief for the proposition that mineral deposits exist in a test area is classified into a binary mineral potential map for the baguio district philippines the binary gold potential map delineates a about 74 of the training data i e locations of large scale gold deposits and b about 64 of the validation data i e locations of small scale gold deposits the results demonstrate the usefulness of a geologically constrained mineral potential mapping using data driven evidential belief functions to guide further surficial exploration work in the search for yet undiscovered gold deposits in the baguio district the results also indicate the usefulness of evidential belief functions for mapping uncertainties in the geologically constrained integrated predictive model of gold potential

controls on mineral deposit occurrence inferred from analysis of their spatial pattern and spatial association with geological features in this paper point pattern analysis fractal analysis and fry analysis were employed to study the spatial pattern of known occurrences of mineral deposits of the type sought whereas distance distribution method was applied to study the spatial associations between various geological features and known occurrences of mineral deposits of the type sought in the aroroy district philippines the results of the applications of these spatial analytical techniques support a conceptual model of district scale mechanism of geologic controls on low sulphidation epithermal au mineralization which involves a more or less regular mesh of interlinked zones of extension faults fractures at and or around intersections of nnw and nw trending strike slip faults fractures integration of spatial evidential data layers representing these structural controls and surficial geochemical anomalies via knowledge guided application of data driven evidential belief functions results in delineation of prospective areas occupying about 25 of the district in which there is about 70 likelihood of undiscovered occurrences of low sulphidation epithermal au deposits

latent thermal effects from porcupine volcanics calderas underlying the white pine presque isle stratiform copper mineralization northern michigan economic stratiform copper mineralization in the fine grained carbonaceous basal nonesuch formation of the 50 km wide white pine presque isle mining district northern michigan has long been explained by the essentially vertical infiltration of cupriferous brine across the full width of basal nonesuch strata from the underlying copper harbor conglomerate aquifer followed by copper precipitation mainly by reactions with in situ iron sulfide based on that model why do lesser amounts of total copper measured in vertical sections occur in coarser grained presumably more permeable basal nonesuch strata situated laterally to the east and west of the mining district the answer may lie in increased infiltration rates for copper harbor hosted ore forming brine warmed locally by latent volcanic heat from a resurgent caldera or calderas located within the large porcupine volcanics dome underlying the mine district not only would caldera heat have warmed the brine and lowered its density but more importantly it would have produced a remarkable decrease in the brine viscosity an increase in temperature from 15 to 100 c could have increased the brine infiltration rate by more than four times in very early diagenetic time when the sediments were poorly compacted and highly porous because progressive compaction would have opposed the temperature effect a very early diagenetic timing is suggested for main stage copper mineralization over the porcupine volcanics caldera textural evidence has also long supported an early mineralization event at the rift basin scale the exceptionally rapid upward flux of warmed brine into fine grained nonesuch over the caldera would have required equivalent volumes of replacement brine which would in turn have required a lateral convergence of brine within the footwall copper harbor conglomerate aquifer toward the white pine presque isle district this lateral focus of brine toward the warm caldera area would have created a more efficient basin scale ore forming system than that resulting from a linear hydrogeologic flow most concepts described here deserve further evaluation through quantitative hydrogeologic modeling thermal effects on ore brine viscosities and densities developed here for the sediment hosted stratiform copper mineralization of the white pine presque isle district could be considered in genetic models for other deposits and deposit types the effects are especially strong for solutions warmed from low temperatures e g 20 c or lower to 100 c and could also be important to ore fluid flow for ores involving much higher hydrothermal temperatures if solutions with initially low temperatures played a role in their genesis

effects of strong ground motion on the susceptibility of gully type debris flows abstract typhoon herb in 1996 caused widespread debris flows in central taiwan the 7 3 chi chi earthquake on september 21 1999 which also took place in central taiwan induced many landslides in the region these landslides turned into debris flows when typhoon toraji struck taiwan in 2001 this research selects three regions which suffered a ground motion class of 5 6 and 7 on the richter scale during the chi chi earthquake as study areas air photos from 1997 and 2001 of these regions are used to map the gully type debris flows that took place after typhoons herb and toraji respectively the gullies adjacent to the debris flow but without a trace of debris flows are also mapped as the non debris flow data the topography hydrogeology and rainfall factors where debris flow occurred and in which there was no occurrence of debris flows in these gullies were retrieved from dtm geological maps and iso countour maps and of rainfall through gis processing these characteristic are introduced into a probabilistic neural network to build a predicting model for the probability of the occurrence of debris flows three series of cross analyses are conducted to compare the probability of the occurrence of debris flows of the same dataset predicted by different prediction models the results reveal that the susceptibility of debris flows was elevated after the chi chi earthquake struck the upsurge of susceptibility was more obvious for the regions that received a higher class of ground motion

evaluation of camel comprehensive areal model of earthquake induced landslides abstract a new comprehensive areal model of earthquake induced landslides camel has been developed to assist in planning decisions related to disaster risk reduction camel provides an integrated framework for modeling all types of earthquake induced landslides using fuzzy logic systems and geographic information systems camel is designed to facilitate quantitative and qualitative representation of terrain conditions and knowledge about these conditions on the likely areal concentration of each landslide type camel has been empirically evaluated with respect to disrupted landslides category i using a case study of the 1989 m 6 9 loma prieta ca earthquake in this case camel performs best in comparison to disrupted slides and falls in soil for disrupted rock fall and slides camel s performance was slightly poorer the model predicted a low occurrence of rock avalanches when none in fact occurred a similar comparison with the loma prieta case study was also conducted using a simplified newmark displacement model the area under the curve method of evaluation was used in order to draw comparisons between both models revealing improved performance with camel camel should not however be viewed as a strict alternative to newmark displacement models camel can be used to integrate newmark displacements with other previously incompatible types of knowledge

evidence for grenville age seismicity and thick skinned deformation in northern wisconsin u s a abstract one of the great continental rifts in all of earth s history the ca 1 1 ga midcontinent rift of the lake superior region was closed and inverted less than 100 m yr after its initiation when rift bounding normal faults were reactivated as reverse faults this was a major crustal event involving thick skinned deformation but its tectonic importance has not been fully appreciated owing in part to the lack of good outcrop along the traces of the rift closing faults a rare exposure of one of these faults occurs near the falls of the marengo river in southeastern bayfield county wisconsin the atkins lake marenisco fault is a crustal scale structure that juxtaposes archean granitic gneisses with paleoproterozoic and neoproterozoic metasedimentary and metavolcanic rocks pseudotachylytes cataclasites and microbreccias in the fault zone record large documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont

early history of the midcontinent rift inferred from geochemistry and sedimentology of the mesoproterozoic osler group northwestern ontario the mesoproterozoic 1108 1105 ma osler group a3k m thick succession of basaltic flows and sedimentary units on the north shore of lake superior is among the oldest expressions of the midcontinent rift basal sediments of the simpson island formation new name deposited by braided fluvial systems record westward transport of debris eroded from local archean and proterozoic rock units strata deposited by this fluvial system are intercalated with and overlain by ocean island basalt oib like basalts which become increasingly contaminated up section end 1100ma 0 3 to 5 3 the light rare earth element lree enriched la smn 1 5 3 9 and heavy ree hree fractionated gd ybn 1 5 3 7 subaerial flows are divisible into two units that correlate with other sections of the osler group to the east but simple correlations with more distant sequences are difficult the volcanic rock dominated portion of the succession is overlain by a thin 25 m thick conglomerate sandstone assemblage representing southeast progradation of an alluvial fan in a semi arid climatic setting clast lithologies and geochemistry indicate no extra rift detritus was delivered from the hinterland of the fan various lines of evidence in both volcanic and sedimentary rocks support a scenario where early pre 1108 ma subsidence along a north south axis from the western arm of the rift to the nipigon embayment was replaced by subsidence along the east west rift axis between 1108 and 1105 ma resume le groupe d osler mesoproterozoique 1108 1105 ma une succession de coulees basaltiques et d unites sedimentaires d une epaisseur de 3 km sur la rive nord du lac superieur est l une des plus anciennes expressions du rift mi continental les sediments a la base de la formation simpson island nouveau nom deposes par un systeme fluvial anastomose enregistrent le transport vers l ouest de debris erodes des unites rocheuses locales archeennes et proterozoiques des basaltes de points chauds recouvrent et sont intercales avec les strates deposees par ce systeme fluvial ces basaltes sont de plus en plus contamines en remontant la section end 1100ma 0 3 to 5 3 les ecoule ments sub aeriens de terres rares legeres enrichies la smn 1 5 3 9 et de terres rares lourdes enrichies fractionnees gd ybn 1 5 3 7 peuvent etre divises en deux unites qui correspondent a d autres sections du groupe d osler vers lst mais de simples correlations avec des sequences plus eloignees sont difficiles la portion de la succession dominee par des roches volcaniques est recouverte d un mince 25 m assemblage conglomerat gres qui represente la prograda tion vers le sud est d un delta alluvionnaire dans un environnement climatique semi aride la lithologie des clastes et la geochimie indiquent qu aucun detritus hors du rift ne provient de l arriere pays du delta diverses preuves a la fois dans les roches sedimentaires et les roches volcaniques soutiennent un scenario selon lequel une subsidence precoce avant 1108 ma le long d un axe nord sud a partir du bras ouest du rift vers la baie nipigon a ete remplacee par de la subsidence le long de l axe est ouest du rift entre 1108 et 1105 ma

a back propagation network for the assessment of susceptibility to rock slope failure in the eastern portion of the southern cross island highway in taiwan an assessment of the susceptibility to rock slope failure by means of a back propagation network is proposed for the eastern portion of the southern cross island highway in taiwan the model was developed on the basis of six influence parameters of rock slope instability which include the rock type slope aspect slope angle joint set number joint spacing and bedding slope relationship the values of these influence parameters were used as inputs for the network and were classified as nominal scales in terms of binary numbers while the state of failure non failure of a given slope was assumed to be the output variable data on a total of 170 slopes along the highway was fed into the network for learning according to the outputs of the network the susceptibility to rock slope failure is categorized into four levels namely low medium low medium and high which are mapped along the highway three highly susceptible regions are found which can be viewed as hazardous sections requiring cautionary measures moreover the proposed model can be used as a tool for determining the possible state of an unfamiliar rock slope in the context of devising management strategies to be applied to the investigated portion of the highway

artificial neural networks and cluster analysis in landslide susceptibility zonation a landslide susceptibility analysis is performed by means of artificial neural network ann and cluster analysis ca this kind of analysis is aimed at using anns to model the complex non linear relationships between mass movements and conditioning factors for susceptibility zonation in order to identify unstable areas the proposed method adopts ca to improve the selection of training validation and test records from data managed within a geographic information system gis in particular we introduce a domain specific distance measure in cluster formation clustering is used in data pre processing to select non landslide records and is performed on the whole dataset excluding the test set landslides susceptibility analysis is carried out by means of anns on the so generated data and compared with the common strategy to select random non landslide samples from pixels without landslides the proposed method has been applied in the brembilla municipality a landslide prone area in the southern alps italy the results show significant differences between the two sampling methods the classification of the test set previously separated and excluded from the training data is always better when the non landslide patterns are obtained using the proposed cluster sampling the case study validates that by means of a domain specific distance measure in cluster formation it is possible to introduce expert knowledge into the black box modelling method implemented by anns to improve the predictive capability and the robustness of the models obtained

modelling shallow landslide susceptibility a new approach in logistic regression by using favourability assessment a new method for estimating shallow landslide susceptibility by combining geographical information system gis nonparametric kernel density estimation and logistic regression is described specifically a logistic regression is applied to predict the spatial distribution by estimating the probability of occurrence of a landslide in a 16 km2 area for this purpose a gis is employed to gather the relevant sample information connected with the landslides the advantages of pre processing the explanatory variables by nonparametric density estimation for continuous variables and a reclassification for categorical discrete ones are discussed the pre processing leads to new explanatory variables namely some functions which measure the favourability of occurrence of a landslide the resulting model correctly classifies 98 55 of the inventaried landslides and 89 80 of the landscape surface without instabilities new data about recent shallow landslides were collected in order to validate the model and 92 20 of them are also correctly classified the results support the methodology and the extrapolation of the model to the whole study area 278 km2 in order to obtain susceptibility maps

landslide susceptibility mapping at central zab basin iran a comparison between analytical hierarchy process frequency ratio and logistic regression models abstract the purpose of this study is to compare the landslide susceptibility mapping models of logistic regression lr analytical hierarchy process ahp and frequency ratio fr applied in the central zab basin west azerbaijan iran eight factors were used for landslide susceptibility mapping including slope aspect land cover precipitation lithology and the distance to roads drainage and faults that affect the occurrence of landslides to get more precision speed and facility in our analysis all descriptive and spatial information was entered into gis system satellite images landsat etm and spot 5 are also used to prepare for land use and landslide inventory mapping respectively landslide events as used as dependant variable and data layers as independent variable making use of the correlation between these two variables in landslide susceptibility the three models are validated using the relative landslide density index r index and the receiver operating characteristic roc curves the predictive capability of each model was determined from the area under the relative operating characteristic curve and the areas under the curves obtained using the lr ahp and fr methods are 0 8941 0 8115 and 0 8634 respectively these results indicate that the lr and fr models are relatively good estimators of landslide susceptibility in the study area the interpretations of the susceptibility map reveal that precipitation lithology and slope played major roles in landslide occurrence and distribution in the central zab basin in general all three models were reasonably accurate the resultant maps would be useful for regional spatial planning as well as for land cover planning

magnetization age from paleomagnetism of the copper harbor red beds northern michigan usa and its keweenawan geologic consequences the copper harbor formation on lake superior s keweenaw peninsula records the transition from volcanic to sedimentary infilling of north america s 1 1 ga keweenawan rift radiometric dating shows t

the geochemistry geochronology and paleomagnetism of dikes and sills associated with the mesoproterozoic midcontinent rift near thunder bay ontario canada abstract the midcontinent rift mcr of north america comprises a series of basaltic sheets flows and intrusive rocks emplaced in the lake superior region during the mesoproterozoic the mafic rocks preserved on the northern flank of lake superior represent the older portions of the rift sequence and offer insights into the early development of the rift new geochronological geochemical and paleomagnetic data are presented for the dikes and sills located in and south of thunder bay ontario three sill suites are recognized within the study area an earlier spatially restricted ultramafic unit termed the riverdale sill the predominant logan sills and nipigon sills in the north of the study area in addition three dike sets are recognized the north east trending pigeon river swarm the north west trending cloud river dikes and the mt mollie dike the geochemical data demonstrate that the majority of sills south of thunder bay are of logan affinity and distinct from those of broadly similar age in the nipigon embayment to the north the pigeon river dikes that intrude the sills are geochemically coherent but distinct from the logan sills and could not be feeders to the sills the new age of 1109 2 4 2 ma for the cloud river dike and its r polarity are consistent with published magnetostratigraphy the mt mollie dike age 1109 3 6 3 ma indicates that it is not coeval with the spatially associated crystal lake gabbro as previously thought the complexity of the dike and sill suites on the northern flank of suggests that the early phases of rifting occurred in distinct and changing stress fields prior to the main extensional rifting preserved in younger rocks to the south the geochemistry and geochronology of the intrusions suggest a long lived and complex magmatic history for the midcontinent rift

landslide susceptibility mapping using geological data a dem from aster images and an artificial neural network ann an efficient and accurate method of generating landslide susceptibility maps is very important to mitigate the loss of properties and lives caused by this type of geological hazard this study focuses on the development of an accurate and efficient method of data integration processing and generation of a landslide susceptibility map using an ann and data from aster images the method contains two major phases the first phase is the data integration and analysis and the second is the artificial neural network training and mapping the data integration and analysis phase involve gis based statistical analysis relating landslide occurrence to geological and dem digital elevation model derived geomorphological parameters the parameters include slope aspect elevation geology density of geological boundaries and distance to the boundaries this phase determines the geological and geomorphological factors that are significantly correlated with landslide occurrence the second phase further relates the landslide susceptibility index to the important geological and geomorphological parameters identified in the first phase through ann training the trained ann is then used to generate a landslide susceptibility map landslide data from the 2004 niigata earthquake and a dem derived from aster images were used the area provided enough landslide data to check the efficiency and accuracy of the developed method based on the initial results of the experiment the developed method is more than 90 accurate in determining the probability of landslide occurrence in a particular area

crustal structure beneath the florida to edmonton broadband seismometer array 1 ps receiver functions were stacked to determine crustal thickness and vp vs ratios for the 28 stations of the florida to edmonton broadband seismometer array and 6 adjacent permanent stations roots of thickened crust exist beneath the paleozoic appalachian orogen and the proterozoic trans hudson orogen the ratios of surface elevation to root thickness are lower than observed in young active orogens as are average crustal root buoyancies determined from gravity data these results are consistent with global trends and may be explained by increased crustal root density due to metamorphism crustal thickening is also observed beneath the mid continent rift in iowa consistent with compressional inversion of the rift during the grenville orogeny

forecasting and validation of landslide susceptibility using an integration of frequency ratio and neuro fuzzy models a case study of seorak mountain area in korea landslides susceptibility maps were constructed in seorak mountain area korea using an integration of frequency ratio and adaptive neuro fuzzy inference system anfis in geographical information system gis environment landslide occurrence areas were detected in the study by interpreting aerial photographs and field survey data landslide locations were randomly selected in a 50 50 ratio for training and validation of the models respectively topography geology soil and forest databases were also constructed maps relevant to landslide occurrence were assembled in a spatial database using the constructed spatial database 17 landslide related factors were extracted the adaptive anfis model with different types of membership functions mfs was then applied for landslide susceptibility mapping in the study area two landslide susceptibility maps were prepared using the different mfs the frequency ratio model was also applied to the landslide susceptibility mapping for comparing with the probabilistic anfis model finally the resulting landslide susceptibility maps were validated using the landslide locations which were not used for training the anfis the validation results showed 75 57 accuracy using the generalized bell shaped mf model 74 94 accuracy using the sigmoidal 2 mf model and 73 07 accuracy using frequency ratio model these accuracy results show that an anfis can be an effective tool in landslide susceptibility mapping

gis based landslide susceptibility assessment in seoul south korea applying the radius of influence to frequency ratio analysis the objective of this paper is to map landslide susceptibility using a statistical analysis model and the radius of influence within a geographic information systems environment the statistical analysis included triggering factors e g topography land cover forest and soil properties of adjacent areas in addition to the landslide sites themselves to estimate the probability of landslide occurrence using the radius of influence and to produce a landslide susceptibility index lsi we performed frequency radio fr analysis by applying the radius of influence to the domain of specific training sites landslide susceptibility maps were generated for each radius of influence ranging from 0 to 300 m in 30 m increments we observed enhanced fr index values corresponding to reduced exaggeration of statistical anomalies within the proper radius of influence it is referred that by adopting the radius of influence the classes that not only affect the landslide occurrence from the adjacent areas but also make anomaly errors can be taken into account in fr analysis moreover comparing the fr values between adopting the optimum radius of influence or not we inferred that the greater the gap the bigger influence of adjacent areas the classes have in the validation stage we identified the optimum radius of influence by measuring the area beneath the relative operating characteristics curve we found that the optimum radius of influence in the study area is 240 m for which the lsi map is 5 95 points more accurate than when not considering the radius of influence

gis based landslide susceptibility analysis using frequency ratio and evidential belief function models this study aimed to produce landslide susceptibility maps using frequency ratio fr and evidential belief function ebf models based on gis for gongliu county china for this purpose a detailed landslide inventory map was prepared and 12 landslide conditioning factors were considered these factors were as follows slope angle slope aspect curvature plan curvature profile curvature altitude the normalized difference vegetation index rainfall the topographic wetness index sti distance from roads distance from rivers and lithology the landslide inventory map was prepared from published sources and aerial photographs supported by field work a total of 233 landslides were identified and mapped in the study area out of which 70 landslides were applied for establishing the model and 30 landslides were used to validate the model gis software was used to analyze landslide conditioning factors and to map landslide susceptibility landslide susceptibility maps were prepared using fr and ebf models based on arcgis 10 0 and classified into five susceptibility zones very low low moderate high and very high finally in order to validate the accuracy of the landslide susceptibility maps produced from two models the area under curve approach was applied the validation results showed that the maps using fr and ebf models have a success rate of 82 41 and 79 69 respectively similarly the maps using fr and ebf models have a predictive rate of 77 26 and 68 79 respectively based on the results both landslide susceptibility maps produced by the two models have a high accuracy and will be helpful for land use planning in the study area

statistical analysis of landslide susceptibility at yongin korea the aim of this study is to evaluate the susceptibility of landslides at yongin korea using a geographic information system gis landslide locations were identified in the yongin area from interpretation of aerial photographs field surveys and maps of the topography soil type timber cover and geology these data were collected and constructed into a spatial database using gis the factors that influence landslide occurrence such as slope aspect and curvature of topography were calculated from the topographic database texture material drainage and effective soil thickness were extracted from the soil database and type age diameter and density of timber were extracted from the forest database lithology was extracted from the geological database and land use was classified from the landsat tm satellite image landslide susceptibility was analyzed using the landslide occurrence factors by probability and logistic regression methods the results of the analysis were verified using the landslide location data the validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide location the gis was used to analyze the vast amount of data efficiently and statistical programs were used to maintain specificity and accuracy the results can be used to reduce associated hazards and to plan land use and construction

landslide susceptibility mapping for ayvalik western turkey and its vicinity by multicriteria decision analysis this paper presents the results of geographical information system gis based landslide susceptibility mapping in ayvalik western turkey using multi criteria decision analysis the methodology followed in the study includes data production standardization and analysis stages a landslide inventory of the study area was compiled from aerial photographs satellite image interpretations and detailed field surveys in total 45 landslides were recorded and mapped the areal extent of the landslides is 1 75 km2 the identified landslides are mostly shallow seated and generally exhibit progressive character they are mainly classified as rotational planar and toppling failures in all 51 45 and 4 of the landslides mapped are rotational planar and toppling types respectively morphological geological and land use data were produced using existing topographical and relevant thematic maps in a gis framework the considered landslide conditioning parameters were slope gradient slope aspect lithology weathering state of the rocks stream power index topographical wetness index distance from drainage lineament density and land cover and vegetation density these landslide parameters were standardized in a common data scale by fuzzy membership functions then the degree to which each parameter contributed to landslides was determined using the analytical hierarchy process method and the weight values of these parameters were calculated the weight values obtained were assigned to the corresponding parameters and then the weighted parameters were combined to produce a landslide susceptibility map the results obtained from the susceptibility map were evaluated with the landslide location data to assess the reliability of the map based on the findings obtained in this study it was found that 5 19 of the total area was prone to landsliding due to the existence of highly and completely weathered lithologic units and due to the adverse effects of topography and improper land use

the 1 1 ga midcontinent rift system central north america sedimentology of two deep boreholes lake superior region abstract the midcontinent rift system mrs of central north america is a 1 1 ga 2500 km long structural feature that has been interpreted as a triple junction rift developed over a mantle plume as much as 20 km of subaerial lava flows mainly flood basalts are overlain by as much as 10 km of sedimentary rocks that are mostly continental fluvial red beds this rock sequence known as the keweenawan supergroup has been penetrated by a few deep boreholes in the search for petroleum in this paper two deep boreholes in the upper peninsula of michigan are described in detail for the first time both the amoco production 1 29r test herein referred to as the st amour well and the nearby hickey creek well drilled by cleveland cliffs mining services were 100 cored the former is 7238 ft 2410 m deep and the latter is 5345 ft 1780 m deep the entirety of the stratigraphic succession of the hickey creek core correlates very well with the upper portion of the st amour core as determined by core description and point counting of 43 thin sections selected out of 100 studied thin sections two lower paleozoic units and two keweenawan red bed units the jacobsville sandstone and the underlying freda sandstone are described the jacobsville is largely a feldspatholithic sandstone and the freda is largely a lithofeldspathic sandstone below the freda the remaining footage of the st amour core consists of a thick quartzose sandstone unit that overlies a heterogenous unit of intercalated red bed units of conglomerate sandstone siltstone and shale black shale individual basalt flows and a basal ignimbritic rhyolite this lower portion of the st amour core presents an enigma as it correlates very poorly with other key boreholes located to the west and southwest while a black shale sequence is similar to the petroleum bearing nonesuch formation farther west there is no conglomerate unit to correlate with the copper harbor conglomerate other key boreholes are distributed over a 1300 km distance along the better known southwest arm of the triple junction mrs and can be correlated rather well with the units that are exposed in the lake superior region however a definitive explanation of the anomalous deeper st amour stratigraphy is elusive and any explanation is tenuous a possible explanation for this anomalous stratigraphy may be the geographic proximity of the st amour borehole to the keweenawan hot spot mantle plume the suggested thermal force behind the development of the mrs similarly a drastic change in structural architecture may be explained by this geographic relationship thus within the locale of this rifting center complexities of expansion tectonics may well be responsible for igneous and sedimentary sequences that differ considerably from those found farther west along the rift arm

selecting and weighting spatial predictors for empirical modeling of landslide susceptibility in the darjeeling himalayas india in this paper we created predictive models for assessing the susceptibility to shallow translational rocksliding and debris sliding in the darjeeling himalayas india by empirically selecting and weighting spatial predictors of landslides we demonstrate a two stage methodology 1 quantifying associations of individual spatial factors with landslides of different types using bivariate analysis to select predictors and 2 pairwise comparisons of the quantified associations using an analytical hierarchy process to assign predictor weights we integrate the weighted spatial predictors through multi class index overlay to derive predictive models of landslide susceptibility the resultant model for shallow translational landsliding based on selected and weighted predictors outperforms those based on all weighted predictors or selected and unweighted predictors therefore spatial factors with negative associations with landslides and unweighted predictors are ineffective in predictive modeling of landslide susceptibility we also applied logistic regression to model landslide susceptibility but some of the selected predictors are less realistic than those from our methodology and our methodology gives better prediction rates although previous predictive models of landslide susceptibility indicate that multivariate analyses are superior to bivariate analyses we demonstrate the benefit of the proposed methodology including bivariate analyses

p wave teleseismic traveltime tomography of the north american midcontinent the remains of the 1 1 ga midcontinent rift mcr lie in the middle of the tectonically stable portion of north america previous and ongoing studies have imaged strong heterogeneity associated with the mcr in the crust but have not imaged such within the mantle it is unclear whether this is due to the absence of rift related mantle structures or these studies had insufficient resolution to image them to address this issue we measured 46 374 teleseismic p wave delay times from seismograms recorded by the usarray transportable array superior province rifting earthscope experiment and surrounding permanent stations we included these and 54 866 delay times from prior studies in our tomographic inversion we find that high velocity anomalies are widespread in our study area but there are also prominent low velocity anomalies two of these are coincident with high bouguer gravity anomalies associated with the mcr in iowa and the minnesota wisconsin border at 50 to 150 km depth extensive resolution testing shows that these anomalies could be the result of downward vertical smearing of relatively low velocities from rift related material that underplated the crust although we cannot exclude that the subcrustal mantle lithosphere beneath the mcr is anomalously enriched hydrated or warm other anomalies occur at syntaxes of the penokean orogen one with the superior province and marshfield terrane in southern minnesota and another with the yavapai and mazatzal terranes both at 100 to 250 km depth in the midmantle we image two linear high velocity anomalies interpreted as subducted fragments of the farallon and kula plates

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

spatial analysis of mutual fault fracture and slope controls on rocksliding in darjeeling himalaya india in this paper the fry analysis was applied to study the spatial patterns in terms of trends of rockslides proportion analysis was applied to study the spatial associations between rockslides and slope aspects and distance distribution analysis was applied to study the spatial associations of rockslides with different sets of faults fractures based on trends in a study area in the darjeeling district india the results of applications of these spatial analytical techniques support a proposition of mutual fault fracture and slope controls on rocksliding in different parts of the study area deep seated rockslides are associated with a ne trending faults fractures and sse facing slopes b nw trending faults fractures and ene facing slopes and c nne trending faults fractures and se or ene facing slopes whereas shallow translational rockslides are associated with a nne trending faults fractures and se nw wnw or wsw facing slopes b wnw trending faults fractures and sw facing slopes c nnw trending faults fractures and ese or sw facing slopes and d nw trending faults fractures with sw facing slopes creating and integrating spatial evidence layers representing mutual fault fracture and slope controls on rocksliding can be achieved satisfactorily via application of evidential belief functions a predictive map of rockslide susceptibility derived by using slope aspects slope inclinations and proximity to the faults fractures that are spatially associated with rockslides is superior to that derives by using slope aspects slope inclinations and proximity to all faults fractures the proposed analytical methods are suitable for first pass regional scale assessment of rockslide susceptibility