biomarker and carbon isotope variation in coal and fossil wood of central europe through the cenozoic abstract carbon isotope analyses of terrigenous organic matter are often used to reconstruct changes in the isotopic composition of upper ocean and atmospheric carbon reservoirs carbon isotope values from tree rings fossil wood and coal matrices have been related to climatic change e g temperature humidity via water use efficiency of land plants in this study we report on carbon isotope analyses on low rank coal deposits of the alpine realm and middle german lignite district covering the early eocene to pliocene time interval fossil wood and extracted wood cellulose from gymnosperms and angiosperms respectively are used for paleoenvironmental reconstructions the trend in 13c is parallel to the carbon isotope record obtained from benthic foraminifera because both data sets sample a common reservoir in the atmosphere the evaluation of the magnitudes of 13c variations of coal caused by environmental change requires the correction of the 13c data due to the effects of different contents of lipids in the organic matter differences in biogeochemical carbon cycling varying contributions of gymnosperms versus angiosperms to peat formation and differences in 13c of atmospheric co2 the resulting carbon isotope record of coal generally co varies with the estimated variability in mean annual temperatures during the tertiary based on paleobotanical data changes in humidity and pco2 may be responsible for deviations between the isotopic trend and the paleotemperature curve during the miocene the obtained temperature coefficient for 13c of c3 plants of about 0 3 c is in agreement with the results of previous studies

structure and contents of a new geomorphological gis database linked to a geomorphological map with an example from liden central sweden this paper presents the structure and contents of a standardised geomorphological gis database that stores comprehensive scientific geomorphological data and constitutes the basis for processing and extracting spatial thematic data the geodatabase contains spatial information on morphography morphometry hydrography lithology genesis processes and age a unique characteristic of the gis geodatabase is that it is constructed in parallel with a new comprehensive geomorphological mapping system designed with gis applications in mind this close coupling enables easy digitalisation of the information from the geomorphological map into the gis database for use in both scientific and practical applications the selected platform in which the geomorphological vector raster and tabular data are stored is the esri personal geodatabase additional data such as an image of the original geomorphological map dems or aerial orthographic images are also included in the database the structure of the geomorphological database presented in this paper is exemplified for a study site around liden central sweden

automated recognition of valley heads from digital elevation models applications of landform recognition in map making geographical information systems and in improving the storage and representation of earth surface information are described reasons are given for the use of digital elevation models for landform recognition increasing availability of data easier data integration and automation of landform recognition an automated technique for recognizing valley heads from digital elevation models is presented the technique has been developed for valley head recognition because valley heads are known locations of geomorphological activity and because areal features have been largely ignored in the automated landform recognition literature the problem of valley head recognition is divided into valley head location and valley head delineation and the technique is developed using a dem representing a simple artificial landscape two methods are given for valley head location in the first valley heads are located at valley ends in the second valley heads are located at cells which would have water flowing into them from many directions if water was flowing over the terrain the latter method locates all the valley heads on the artificial landscape the cells locating valley heads are iteratively grown to adjacent cells that are concave in plan and not flat to delineate the valley head at best 82 per cent valley head cells on the artificial landscape are correctly recognized with a 43 per cent commission error the method is tested on real data where it is less successful because of the variability of real landscapes and the inadequacy of the methods chosen for valley network delineation machine learning of thresholds and a method involving inspection of profiles across a dem cell are suggested as methods to improve the automated valley head recognition technique

automated mapping of land components from digital elevation data an algorithm for automating the mapping of land components from digital elevation data is described land components are areas of relatively uniform slope and aspect and often correspond with ridge crests shoulders head slopes back slopes or foot slopes aspect regions which generally span from stream to ridge are first identified by generalizing an aspect map derived from digital elevation data the aspect regions are then split successively into land components by grouping pixels above or below an automatically determined contour of elevation or distance from stream the contour approximates a slope break the land components mapped in this way give a complete polygonization of a hilly landscape and are a reasonable approximation of manually mapped land components

random forest with semantic tie points for classifying landforms and creating rigorous shaded relief representations abstract in this study we tested random forest rf with semantic tie points to classify discrete landforms which would be ultimately useful for increasing the accuracy of shaded relief representations we therefore focused our efforts on the following landforms rock outcrops screes alluvial fans and low relief areas a characteristic of rf which makes it a good algorithm for geomorphological mapping is its ability to generate thousands of classification trees each tree provides a classification and the value classified by the majority of the trees is the final output of the algorithm furthermore having multiple classifications provides a measure of uncertainty this is very important because it gives practitioners an idea of areas where the method is less accurate which would require more effort in terms of sampling or surveying this method was applied in two mountainous areas of switzerland the first where we trained and calibrated it and the second where we used it for classification the results were validated using existing geomorphological maps and they show that this method can obtain good training accuracy with a relatively small starting dataset moreover both calibration and classification present a percentage of agreement with existing geomorphological maps of over 70 some geomorphological classes alluvial fans and screes present a classification accuracy that is lower than the calibration which is in line with previous tests found in the literature however for other classes i e rock outcrops and low relief areas the accuracy increases suggesting that this method can be employed extensively and relatively securely for these landforms

integration of spectral spatial and morphometric data into lithological mapping a comparison of different machine learning algorithms in the kurdistan region ne iraq abstract lithological mapping in mountainous regions is often impeded by limited accessibility due to relief this study aims to evaluate 1 the performance of different supervised classification approaches using remote sensing data and 2 the use of additional information such as geomorphology we exemplify the methodology in the bardi zard area in ne iraq a part of the zagros fold thrust belt known for its chromite deposits we highlighted the improvement of remote sensing geological classification by integrating geomorphic features and spatial information in the classification scheme we performed a maximum likelihood ml classification method besides two machine learning algorithms mla support vector machine svm and random forest rf to allow the joint use of geomorphic features band ratio br principal component analysis pca spatial information spatial coordinates and multispectral data of the advanced space borne thermal emission and reflection radiometer aster satellite the rf algorithm showed reliable results and discriminated serpentinite talus and terrace deposits red argillites with conglomerates and limestone limy conglomerates and limestone conglomerates tuffites interbedded with basic lavas limestone and metamorphosed limestone and reddish green shales the best overall accuracy 80 was achieved by random forest rf algorithms in the majority of the sixteen tested combination datasets

geomorphons a pattern recognition approach to classification and mapping of landforms abstract we introduce a novel method for classification and mapping of landform elements from a dem based on the principle of pattern recognition rather than differential geometry at the core of the method is the concept of geomorphon geomorphologic phonotypes a simple ternary pattern that serves as an archetype of a particular terrain morphology a finite number of 498 geomorphons constitute a comprehensive and exhaustive set of all possible morphological terrain types including standard elements of landscape as well as unfamiliar forms rarely found in natural terrestrial surfaces a single scan of a dem assigns an appropriate geomorphon to every cell in the raster using a procedure that self adapts to identify the most suitable spatial scale at each location as a result the method classifies landform elements at a range of different spatial scales with unprecedented computational efficiency a general purpose geomorphometric map an interpreted map of topography is obtained by generalizing allgeomorphons to a small number of the most common landform elements due to the robustness and high computational efficiency of the method high resolution geomorphometric maps having continental and even global extents can be generated from giga cell dems such maps are a valuable new resource for both manual and automated geomorphometric analyses in order to demonstrate a practical application of this new method a 30 m cell 1 geomorphometric map of the entire country of poland is generated and the features and potential usage of this map are briefly discussed the computer implementation of the method is outlined the code is available in the public domain

application of self organizing map and srtm data to characterize yardangs in the lut desert iran abstract yardangs an exclusive landform due to intensive wind erosion cover a large area in the hyper arid lut desert of iran this paper presents a new approach using self organizing map som as unsupervised algorithm of artificial neural networks for analysis and characterization of yardangs nowadays the shuttle radar topography mission srtm with 3 arc sec data approximately 90 m resolution and nearly world wide coverage provides uniform good quality data the srtm 3 arc sec data were re projected to a 90 m utm grid bivariate quadratic surfaces with moving window size of 5 5 were fitted to this dem the first derivative slope steepness and the second derivatives minimum maximum curvature and cross sectional curvatures were calculated as geomorphometric parameters used as input to the soms 42 soms with different learning parameter settings e g initial and final radius number of iterations and the effect of random initial weights on average quantization error were investigated a som with a low average quantization error 0 1040 was used for further analysis feature space analysis morphometric signatures three dimensional inspection auxiliary data like landsat etm and high resolution satellite imagery from quickbird facilitated the assignment of semantic meaning to the output classes in terms of geomorphometric features results are provided in a geographic information system as thematic maps of landform entities based on form and slope e g yardangs ridge corridors valley or planar areas the results showed that all yardangs and corridors were clearly recognized and classified by this method when their width was larger than the dem resolution but became unrecognizable if their width is much smaller than the grid resolution the identified yardangs and corridors are aligned nnw sse parallel to the prevailing direction of the strong local 120 days wind and cover about 31 and 42 of the study area respectively the results demonstrate that som is a very efficient tool for analyzing aeolian landforms in hyper arid environments that provides very useful information for terrain feature analysis in remote regions

digital terrain modelling a review of hydrological geomorphological and biological applications the topography of a catchment has a major impact on the hydrological geomorphological and biological processes active in the landscape the spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques many geographic information systems are being developed that store topographic information as the primary data for analysing water resource and biological problems furthermore topography can be used to develop more physically realistic structures for hydrologic and water quality models that directly account for the impact of topography on the hydrology digital elevation models are the primary data used in the analysis of catchment topography we describe elevation data sources digital elevation model structures and the analysis of digital elevation data for hydrological geomorphological and biological applications some hydrologic models that make use of digital representations of topography are also considered

machine learning based mapping of micro topographic earthquake induced paleo pulju moraines and liquefaction spreads from a digital elevation model acquired through laser scanning abstract the advent of public open source airborne laser scanning produced digital elevation models als dem has provided new perspectives on glacial geomorphology in the nordic countries seismically induced micro topographic paleo landforms can now be identified and mapped throughout the former fennoscandian ice sheet allowing spatial safety assessment for nuclear waste disposal automated machine learning techniques enable recognition of these fine scale geomorphological features efficiently and in a consistent way nationwide the current study focuses on automated recognition of paleo liquefaction spreads and pulju moraines in northern finland geomorphometric variables in different cell sizes were first derived from the 2 m als dem by gabor and principal curvature filtering to emphasize the elevational multi scale texture of these paleo seismic landforms the gabor textural variables were considered as a baseline method and the principal curvature features including maximum and minimum curvature were used because they have previously been proven critical in recognition of concave and convex elongated features both sets of raster variables were then turned into histogram based features and input into a non linear supervised multilayer perceptron early stop committee which is a neural network classifier the leave one out cross validation performance results indicated principal curvature features to be highly successful with 94 accuracy principal curvatures provided a clear improvement to gabor based features which provided significantly lower accuracies between 83 and 85 the study demonstrates the high success of supervised neural network based classification of als dem data and derived textural features capturing the multi scale nature of the micro topographic liquefaction spreads and pulju moraines the approach could be utilized for time efficient mapping of these paleo seismic geomorphologies to complete paleo seismic databases in formerly glaciated regions

towards a definition of topographic divisions for italy abstract the study has divided italy into eight major topographic divisions provinces and 30 minor divisions sections that are similar to n fenneman s units of the united states provinces and sections are generally consistent with observed morphology the new units were defined step wise in a semi quantitative approach that combined an unsupervised three class cluster analysis of four derivatives of altitude visual interpretation of morphometric maps including shaded relief and comparative inspection of small scale geological and structural maps the four variables are altitude slope curvature frequency of slope reversal and elevation relief ratio highland upland and lowland topographic types were identified the variables were computed from a 230 m resolution digital terrain model regridded from the original 230 m dem obtained by mosaicking the entire italian mean elevation archive

mesoarchaean aluminous rocks at storo southern west greenland new age data and evidence of premetamorphic seafloor weathering of basalts abstract metamorphosed meso to neoarchaean supracrustal rocks in the central part of the island of storo nuuk region southern west greenland show field and geochemical evidence of premetamorphic chemical alteration this alteration changed basaltic precursors into aluminous lithologies and following amphibolite grade metamorphism and penetrative ductile deformation these garnet biotite schists now resemble adjacent metapelitic schists of sedimentary origin mass balance calculations isocon method suggests that most major elements si fe mg ca na and p were leached during alteration the calculated overall net mass changes are between 18 and 45 consistent with breakdown of olivine pyroxenes plagioclase and apatite in the basaltic precursor rocks major and trace elements such as k cs rb ba pb zn la and ce were added during this alteration process whereas high field strength elements ti al zr hf and nb remained essentially immobile and were thus residually enriched interestingly th which is generally assumed to be immobile in fluids was also added during this process these chemical changes reflect interaction between a basaltic protolith and hydrous fluids that established a new equilibrium and thus a different mineral assemblage it is proposed that the premetamorphic alteration at storo was due to low temperature interaction between seawater and oceanic crust and thus essentially represents in situ submarine seafloor weathering this interpretation is consistent with the mass balances reported from well documented examples in younger settings new u pb zircon geochronology from the arc related mafic sequences at storo shows that they comprise at least two distinct age groups an older anorthosite complex dated at 3051 3 2 6 ma and a younger supracrustal sequence with age brackets between 2840 and 2710 ma the allochthonous nature of these two mafic igneous to sedimentary stacks is consistent with accretionary processes in island arc complexes and a compressional archaean tectonic setting

fossil wood carbon isotope stratigraphy of the non marine wealden group lower cretaceous southern england fossil wood carbon isotope data are presented for the wessex formation a non marine unit within the lower cretaceous valanginian barremian wealden group of the isle of wight and dorset southern england the carbon isotope values have a range 13 c c 26 6 to 19 8 that is consistent with that expected for mesozoic c 3 plants consideration of the isle of wight fossil wood carbon isotope data together with data from dorset allows construction of a composite fossil wood carbon isotope curve for almost the entire wealden group the new carbon isotope curve is in smooth continuity with data previously published from the overlying lagoonal vectis formation and marine lower greensand group of aptian age a tentative correlation with a tethyan reference carbon isotope curve allows the provisional application of stage level chronostratigraphy to the wealden group correlations suggest that the wealden group sediments are dominantly of hauterivian and barremian age and that the valanginian is either condensed or partially missing the carbon isotope data presented indicate that even during times of relative carbon cycle quiescence atmosphere co 2 faithfully tracks the carbon isotopic composition of the oceanic reservoir

spatial and temporal evolution of an avulsion on the taquari river distributive fluvial system from satellite image analysis avulsion processes have been observed and analyzed using field based studies however they have rarely been analyzed through use of satellite imagery even though such an approach allows documentation of spatial and temporal variations of the resulting deposits in order to document changes that are occurring at the caronal avulsion on the taquari river brazil a time series of landsat imagery from 1985 to present 2010 was compiled as of july 2010 the imagery shows that the avulsion is not yet complete with discharge being routed to both the parent channel and the avulsion channel in the floodbasin the avulsion was initiated as flow was diverted from the parent channel to the floodbasin through two small crevasses allowing the development and evolution of splays with a single splay stabilizing only since 1999 the avulsion area is marked by the growth of new splays the formation of an avulsion belt and progradation of avulsion deposits into the floodbasin the parent channel downstream of the avulsion site has experienced decreasing width through time associated with the higher volumes of water and sediment being captured by the avulsion channel because this avulsion is not yet complete we expect more morphological changes to occur as the avulsion belt evolves into the primary channel rapid sedimentation caused by this avulsion and the 24 year time series of imagery that captured this change allowed us to construct a 3d block representing the evolution of depositional environments associated with avulsion using time in the vertical dimension thus we could represent the evolution of geomorphological patterns including floodbasin proximal levee distal levee and channel deposits and project their distributions through time this block of evolving sedimentary settings can be used as a guide for future sedimentologic studies by offering visual clues regarding the way which depositional systems track avulsion initiated changes

miocene depositional environment and climate in western europe the lignite deposits of the lower rhine basin germany abstract miocene lignites representing a depositional history of about 7 million years 18 11 ma before present have been studied by organic petrological and organic geochemical methods including analysis of stable carbon and oxygen isotopes the three lignite seams investigated morken frimmersdorf garzweiler developed from peats which grew in a nutrient depleted paralic environment situated close to the sea all seams have low ash mineral matter contents but seam frimmersdorf is richer in sulfur as compared to seams morken and garzweiler sulfur richness and distribution in seam frimmersdorf might be due to the diagenetic effect of sulfate reduction and pyrite precipitation following flooding by the sea and deposition of the marine neurath sands on top of seam frimmersdorf geochemical palaeotemperature analysis gdgt revealed a warm climate during deposition of the peats representing lignite seams morken and frimmersdorf which shifted towards lower temperatures 2 3 c during deposition of the uppermost seam garzweiler i e at about 13 11 ma before present this trend is basically supported by cellulose oxygen isotope values which show a significant scatter however carbon isotope values are less variable indicating predominance of angiosperms in the peat vegetation and rather stable environmental conditions as well as floral assemblage organic petrological studies reveal predominance of small plants and a nutrient depleted environment a modified groundwater index gwiac was applied suggesting deposition above the general groundwater level

a method for combining srtm dem and aster gdem2 to improve topography estimation in regions without reference data abstract digital elevation models dems such as advanced spaceborne thermal emission and reflection radiometer global digital elevation models aster gdem or shuttle radar topography mission dem srtm are widely used in remote areas and non industrial countries because of their availability rather than their accuracy although a global dem can be considerably enhanced using additional reference information such as higher resolution dems or ground truth points improving accuracy in areas without reference data remains a challenge this paper develops an approach to improve the accuracy of the estimated topography by combining two complementary dems aster gdem 1 arc second and srtm dem 1 arc second in regions missing reference data the combination approach is based on formulating relationships between slopes and weights in sites with reference data then the developed relationships are applied to sites with similar geomorphology to determine the combination weight for each dem without using reference data the results indicate that combined dems offer significant improvements of 47 and 20 in mean bias over a mountainous site and 16 and 58 at a low relief site when compared with the srtm and aster gdem products respectively dem derived drainages were also found to be more accurate for the combined dems than the near global dems in areas where reference data is not available

gold prospectivity maps of the red lake greenstone belt application of gis technology recent advances in the use of geographic information systems gis software and analysis can be used in conjunction with traditional geoscience data sets to determine effective predictors for gold mineralization from which mineral prospectivity maps can be generated that highlight potential exploration targets on a regional scale in this paper key components of the archean lode gold deposit model for the red lake belt are selected and modeled using weights of evidence wofe analysis and logistic regression leading to the creation of gold prospectivity maps the best predictors for past and present gold producers in the red lake camp according to wofe analysis include 1 elevated trace elements au as and sb 2 a number of alteration indices calculated from oxide geochemical data 3 alteration characterized by pervasive and vein style ferroan carbonate and elevated au as sb and s anomalies 4 proximity to the mackenzie island stock and diorite phases of the dome stock and 5 tholeiitic

drumlins and the dynamics of the subglacial environment abstract this volume contains a selection of papers presented at the vii international drumlin symposium westport ireland in may 2009 this introduction to the volume first outlines the significance of drumlins as a key subglacial bedform gives a brief history of drumlin research and identifies the major themes of subglacial research namely mapping and morphometry sedimentary and ice bed processes and glacier dynamics it then summarises in turn the major findings of the papers in this volume linking them to each other and to the wider literature finally this introductory paper considers future developments in studies of drumlins and the subglacial environment

relationship between co2 dominated fluids hydrothermal alterations and gold mineralization in the red lake greenstone belt canada abstract the red lake greenstone belt is one of the foremost au mining camps in canada and hosts the world class campbell red lake au deposit belt scale hydrothermal alteration is characterized by proximal ferroan dolomite zones associated with au mineralization surrounded by distal calcite zones both being accompanied by potassic alterations sericite muscovite and biotite at the campbell red lake and cochenour deposits au mineralization in particular high grade ore is associated with silica and sulfides especially arsenopyrite that replace carbonate quartz veins and the host rocks the prevalence of carbonic fluid inclusions and rare occurrence of aqueous bearing inclusions in carbonate quartz au veins in the campbell red lake deposit and the consistency of homogenization temperatures of carbonic inclusions within individual fluid inclusion assemblages fia have been interpreted to indicate that h2o poor co2 dominated fluids were responsible for the carbonate veining and au mineralization further studies of fluid inclusions in carbonate quartz veins within and outside the deformation zone hosting the campbell red lake deposit the red lake mine trend including the cochenour au deposit the redcon au prospect and outcrops in the distal calcite zone also reveal the dominance of carbonic fluid inclusions in vein minerals these studies indicate that co2 dominated fluids were flowing through fractures during carbonate vein formation and au mineralization both within and outside major structures the carbonic fluid may have been initially undersaturated with water or it may have resulted from phase separation of an h2o co2 nacl fluid in the latter case phase separation modeling indicates that the initial fluid likely had x co 2 values larger than 0 8 calculations based on hydrothermal mineral assemblages indicate x co 2 values in the host rocks from 0 025 to 0 85 reflecting a change from co2 dominated fluids in the fractures veins to h2o dominated fluids in the host rocks away from the fractures the co2 dominated fluids were likely advected from granulite facies in the deeper crust whereas the h2o dominated fluids were derived from the ambient host rocks of amphibole to greenschist facies calculations based on co2 requirements and source constraints indicate that the mineralizing fluids were likely two orders of magnitude more enriched in au than the commonly assumed values of a few g l which may explain why the campbell red lake deposit has a very high grade of au average 21 g t for the whole deposit and 81 g t for the goldcorp high grade zone fluid inclusion data suggest that the carbonate veining and au mineralization likely took place at depths from 7 to 14 km the development of crustiform colloform structures in the carbonate quartz veins which was previously interpreted to indicate relatively shallow environments may alternatively have been related to extremely high fluid pressures and the co2 dominated nature of the fluids which could have enhanced the brittle properties of the rocks due to their high wetting angles

characteristics and origin of archean premetamorphic hydrothermal alteration at the campbell gold mine northwestern ontario canada the campbell mine located in northwestern ontario canada is developed within a metamorphosed and deformed fault controlled archean gold deposit hosted predominantly within basalt and ultramafic rocks with lesser quantities of rhyolite and diorite the sequence of hydrothermal alteration has been subdivided into three partially overlapping phases consisting of an early alteration phase followed by the main stage vein phase and culminating in the mineralization phase early alteration consists of two substages represented by carbonatization and pervasive biotite potassic alteration and early silicification and aluminosilicate bearing alteration carbonate alteration is relatively wide spread whereas biotitic alteration occurs proximal to alteration controlling structures in highly carbonatized and or silicified rocks carbonate biotite alteration grades into carbonate chlorite alteration laterally outward

lithological mapping of the troodos ophiolite cyprus using airborne lidar topographic data traditional field based lithological mapping can be a time consuming costly and challenging endeavour when large areas need to be investigated where terrain is remote and difficult to access and where the geology is highly variable over short distances consequently rock units are often mapped at coarse scales resulting in lithological maps that have generalised contacts which in many cases are inaccurately located remote sensing data such as aerial photographs and satellite imagery are commonly incorporated into geological mapping programmes to obtain geological information that is best revealed by overhead perspectives however spatial and spectral limitations of the imagery and dense vegetation cover can limit the utility of traditional remote sensing products the advent of airborne light detection and ranging lidar as a remote sensing tool offers the potential to provide a novel solution to these problems because accurate and high resolution topographic data can be acquired in either forested or non forested terrain allowing discrimination of individual rock types that typically have distinct topographic characteristics this study assesses the efficacy of airborne lidar as a tool for detailed lithological mapping in the upper section of the troodos ophiolite cyprus morphometric variables including slope curvature and surface roughness were derived from a 4 m digital terrain model in order to quantify the topographic characteristics of four principal lithologies found in the area an artificial neural network the kohonen self organizing map was then employed to classify the lithological units based upon these variables the algorithm presented here was used to generate a detailed lithological map which defines lithological contacts much more accurately than the best existing geological map in addition a separate map of classification uncertainty highlights potential follow up targets for ground based verification the results of this study demonstrate the significant potential of airborne lidar for lithological discrimination and rapid generation of detailed lithological maps as a contribution to conventional geological mapping programmes

temperatures and oxygen isotopic composition of phanerozoic oceans abstract the temperature of ancient oceans is an important constraint for understanding the climate history of our planet the classical oxygen isotope paleothermometry on fossil shells while very proficient when applied to the younger cenozoic portion of the geologic record is believed to yield only unreliable results for the phanerozoic deep time either because the empirically well documented secular trend to more negative 18 o values with increasing age was generated by post depositional recrystallization processes or if primary implies ecologically unpalatable hot early oceans here we present a compilation of 18 o measurements for 58 532 low mg calcite marine shells that cover almost the entire phanerozoic eon argue that the secular decline of about 6 is primary propose that it reflects the changing oxygen isotopic composition of sea water and define a new baseline trend for 18 o of paleo sea water the latter providing a new template for calculation of ambient habitat temperatures of fossil specimens the resulting pattern for fossil taxa foraminifera brachiopods belemnites and bivalves mimics their modern counterparts in temperature ranges and modes this conceptual framework enables application of actualistic concepts to ambient habitat temperatures of fossils and provides us with a long overdue tool for interpretation of deep time geologic history

automatic relief classification versus expert and field based landform classification for the medium altitude mountain range the sudetes sw poland abstract the main purpose of the study is to compare the results of automatic classification of landforms performed as unsupervised classification and manual expert morphographic landform classification derived from field mapping and recognition of long term trends in landform evolution two test areas in the sudetes mountains sw poland were selected each representing a different type of relief the jelenia gora basin is an example of denudational hilly granite topography with inselbergs other residual hills and basins whereas the northern part of the bystrzyckie mountains is a faulted plateau underlain by sedimentary and metamorphic rocks the setup of the classification involved a dem derived from digitalization of 1 25 000 maps a filter mask of 20 20 pixels 500 500 m k median cluster analysis and consideration of four dimensions relative height slope combined curvature and aspect we used a statistical criterion to decide the level of classification i e the number of homogeneous groups returned output maps show the results of classification into five jelenia gora basin or six groups bystrzyckie mountains later confronted with nine group classification in both areas automatic classification for k 5 6 performed well and the principal features of relief are well captured despite very different landform patterns and long term geomorphic histories slope and curvature are the main variables to differentiate individual terrain units landforms with an additional role of aspect in the faulted and tilted plateau for k 6 aspect becomes the main variable in the hilly relief and the pattern of terrain units becomes more fragmented adversely impacting on the clarity of interpretation while surfaces in the faulted plateau setting are further subdivided according to slope and curvature the match between expert maps and the results of automatic classification varies depending on the landforms considered while certain landforms are clearly associated with one particular group yielded by automatic classification others fall into a number of groups and do not have distinctive signatures despite different origins

upper cretaceous stable carbon isotope stratigraphy of terrestrial organic matter from sakhalin russian far east a proxy for the isotopic composition of paleoatmospheric co2 abstract time stratigraphic patterns of stable carbon isotopic ratios recorded in terrestrial organic matter from cenomanian maastrichtian successions for the russian far east can be correlated to those of carbonate carbon from well studied successions for other parts of the world age indicative biostratigraphy based on regional ammonoids and inoceramid bivalves are well established in japan and can be applied to the whole cretaceous succession except for the upper cenomanian lower turonian and the upper part of the maastrichtian zones lacking macrofossils globally correlative carbon isotopic events previously documented with carbonate carbon from europe and with carbonate carbon and marine organic matter from the u s western interior are recognized with similar magnitude through uppermost cenomanian lower campanian in ascending order these events are positive spike across the cenomanian turonian boundary step like leveled segment followed by negative shift lower middle turonian trough like negative excursion middle upper turonian positive rebound coupled with following broad peak coniacian and positive peak basal campanian followed by modest negative excursion the parallel fluctuation of the 13 c value between the terrestrial organic matter and carbonate suggests carbon isotopic equilibrium between surface seawater and atmospheric co 2 and demonstrates that the isotopic curve of terrestrial organic carbon can be used to monitor carbon isotopic fluctuations of co 2 in the ocean atmosphere system in the upper campanian and maastrichtian a negative 13 c excursion within chron 33r and a following rapid rebound can be correlated with the same distinctive carbon isotopic feature of carbonate observed in the deep sea cores from south and north atlantic the indian and the pacific oceans within this interval the 13 c value of terrestrial organic matter also reflects carbon isotopic fluctuation of the global co 2 reservoir with relatively minor regional local noise

timing of gold mineralization at red lake northwestern ontario canada new constraints from u pb geochronology at the goldcorp high grade zone red lake mine and the madsen mine the goldcorp high grade zone at the red lake mine has reserves proven and probable established at 1 775 million tons mt at an average grade of 80 6 g t au new u pb geochronologic data combined with detailed mapping and crosscutting relationships provide timing constraints and new insights into the formation of the exceptionally rich goldcorp high grade zone the results show that the main stage of the high grade mineralization in the high grade zone formed before 2712 ma and that a second stage of gold mineralization much smaller in terms of total gold content but spectacular in terms of grade formed after 2702 ma this second stage is attributed to gold remobilization caused by the enhanced thermal gradient and deformation associated with the emplacement of the cat island pluton 2699 ma approximately 7 km east of the deposit or by the ca 2 63 to 2 66 ga postorogenic regional thermal event indicated by hornblende muscovite and biotite ar ar cooling ages from the uchi subprovince it is proposed that the main stage of high grade mineralization formed between ca 2723 to 2712 ma possibly synchronous with emplacement of the dome and mckenzie island stocks the abino granodiorite and hammell lake batholith as well as with penetrative d2 main stage regional deformation lamprophyre dikes spatially associated with the deposit postdate main stage mineralization by at least 10 m y a postore granodiorite dike from the madsen mine the second largest deposit in the district was dated at 2698 1 ma this age is similar to a postalteration and late deformation diorite dike at the creek zone showing near the former starratt olsen mine which was dated at 2696 2 ma the crosscutting relationships confirm that the main stage of mineralization at the madsen mine is pre 2698 ma a folded and metamorphosed polymictic conglomerate located stratigraphically above the campbell red lake deposit and deposited after ca 2747 but before 2712 ma is correlated with the newly recognized huston assemblage crosscutting and overprinting relationships between the conglomerate and the alteration indicate protracted multistage aluminous and iron carbonate quartz veining and or alteration event s before and after deposition of the conglomerate the age of the conglomerate confirms that the campbell red lake deposit is proximal to a folded regional unconformity consistent with the empirical relationship between large gold deposits and unconformities elsewhere in archean greenstone belts this paleosurface represents a key first order exploration target and it is proposed that areas of high potential for gold exploration in red lake occur in the balmer assemblage rocks within 500 m to 1 km of the unconformity

stable carbon isotope record of terrestrial organic materials for the last 450 ma yr abstract the timing and magnitude of carbon isotope excursions is essential for understanding the global transfer of carbon among the oceansland and atmosphere numerous studies have focused on data collection of stable carbon isotopes 13c from marine sediments and by extension to the atmosphere but many fewer systematic studies have been conducted on land plants over long time intervals we pursued three approaches to determining stable carbon isotope trends for the past 450 ma yr from c3 plants 13cp in 5 ma yr time steps first a compilation of 6888 13cp values from ten carbon sources from the literature average 24 6 1 7 isoorg data base the second approach assumes the 13cp is controlled primarily by the 13c of atmospheric co2 13ca and subsequent isotopic fractionation from diffusion and carboxylation during photosynthesis mod1 the third approach assumes changes in atmospheric co2 concentration pco2 causes physiological driven isotopic fractionation during photosynthesis when pco2 is greater than average holocene conditions mod2 compared to isoorg and mod1 mod2 reveals lower 13cp by up to 6 during periods when pco2 is elevated as secular governors of 13cp the 13ca and pco2 are most influential when they are directional and amplify the isotopic signal despite potential influences from local and regional environmental conditions and averaging the 13cp of multiple plant sources in many of the 5 ma yr age bins ten positive carbon isotopic excursions pcies are identified in isoorg of this study most of the excursions occurred during cool to glacial conditions or ocean anoxic events one prominent negative isotopic excursion ensued from 260 to 240 ma yr which may have been a response to oxidation of light c methane outbursts volcanic eruptions or bolide impact

formation of the campbell red lake gold deposit by h 2 o poor co 2 dominated fluids the campbell red lake gold deposit in the red lake greenstone belt with a total of approximately 840 t of gold past production reserves and an average grade of 21 g t au is one of the largest and richest archean gold deposits in canada gold mineralization is mainly associated with silicification and arsenopyrite that replace carbonate veins breccias and wallrock selvages the carbonate veins and breccias which are composed of ankerite quartz and characterized by crustiform cockade textures were formed before and or in the early stage of penetrative ductile deformation whereas silicification arsenopyrite replacement and gold mineralization were coeval with deformation microthermometry and laser raman spectroscopy indicate that fluid inclusions in ankerite and associated quartz q1 and main ore stage quartz q2 are predominantly carbonic composed mainly of co2 with minor ch4 and n2 aqueous and aqueous carbonic inclusions are extremely rare in both ankerite and quartz h2o was not detected by laser raman spectroscopic analyses of individual carbonic inclusions and by gas chromatographic analyses of bulk samples of ankerite and main ore stage quartz q2 fluid inclusions in post mineralization quartz q3 are also mainly carbonic but proportions of aqueous and aqueous carbonic inclusions are present trace amounts of h2s were detected by laser raman spectroscopy in some carbonic inclusions in q2 and q3 and by gas chromatographic analyses of bulk samples of ankerite and q2 3he 4he ratios of bulk fluid inclusions range from 0 008 to 0 016 ra in samples of arsenopyrite and gold homogenization temperatures th co2 of carbonic inclusions are highly variable from 4 1 to 30 4 c mostly to liquid some to vapor but the spreads within individual fluid inclusion assemblages fias are relatively small within 0 5 to 10 3 c carbonic inclusions occur both in fias with narrow th co2 ranges and in those with relatively large th co2 variations the predominance of carbonic fluid inclusions has been previously reported in a few other gold deposits and its significance for gold metallogeny has been debated some authors have proposed that formation of the carbonic fluid inclusions and their predominance is due to post trapping leakage of water from aqueous carbonic inclusions h2o leakage model whereas others have proposed that they reflect preferential trapping of the co2 dominated vapor in an immiscible aqueous carbonic mixture fluid unmixing model or represent an unusually h2o poor co2 dominated fluid single carbonic fluid model based on the fia analysis reported in this study we argue that although post trapping modifications and host mineral deformation may have altered the fluid inclusions in varying degrees these processes were not solely responsible for the formation of the carbonic inclusions the single carbonic fluid model best explains the extreme rarity of aqueous inclusions but lacks the support of experimental data that might indicate the viability of significant transport of silica and gold in a carbonic fluid in contrast the weakness of the unmixing model is that it lacks unequivocal petrographic evidence of phase separation if the unmixing model were to be applied the fluid prior to unmixing would have to be much more enriched in carbonic species and poorer in water than in most orogenic gold deposits in order to explain the predominance of carbonic inclusions the h2o poor co2 dominated fluid may have been the product of high grade metamorphism or early degassing of magmatic intrusions or could have resulted from the accumulation of vapor produced by phase separation external to the site of mineralization

supervised classification of types of glaciated landscapes using digital elevation data abstract automated approaches for identifying different types of glaciated landscapes using digitally processed elevation data were evaluated we tested the ability of geomorphic measures e g elevation relative relief roughness and slope gradient derived from digital elevation models dems to differentiate glaciated landscapes using maximum likelihood classification and artificial neural networks ann the automated methods were trained and validated using an existing quaternary geology map and a manual interpretation of the contour data portrayed on topographic quadrangles the need for such methods arises from efforts to classify types of landscapes e g ecoregions in michigan one fundamental control of the landscape structure in michigan including soil type and vegetation is the underlying sedimentary and landform assemblages produced by an array of glacial processes during the waning phase of the pleistocene traditional methods for identifying different landscapes e g ice contact landscapes stagnation landscapes have relied on printed topographic maps and have been very effective but time consuming the maps resulting from the four supervised classification trials had between 51 and 61 agreement with the original quaternary geology map the output from the maximum likelihood classification had slightly higher agreements than the output from the neural net which is attributed to the generalization inherent in the quaternary geology map compared with the nature of the classifier for the neural net the neural net however identifies significant detail and non linear relationships between classification inputs and output classes future work should incorporate a map of soils into the classification

evaluation of current statistical approaches for predictive geomorphological mapping abstract predictive models are increasingly used in geomorphology but systematic evaluations of novel statistical techniques are still limited the aim of this study was to compare the accuracy of generalized linear models glm generalized additive models gam classification tree analysis cta neural networks ann and multiple adaptive regression splines mars in predictive geomorphological modelling five different distribution models both for non sorted and sorted patterned ground were constructed on the basis of four terrain parameters and four soil variables to evaluate the models the original data set of 9997 squares of 1 ha in size was randomly divided into model training 70 n 6998 and model evaluation sets 30 n 2999 in general active sorted patterned ground is clearly defined in upper fell areas with high slope angle and till soils active non sorted patterned ground is more common in valleys with higher soil moisture and fine scale concave topography the predictive performance of each model was evaluated using the area under the receiver operating characteristic curve auc and the kappa value the relatively high discrimination capacity of all models auc 0 85 0 88 and kappa 0 49 0 56 implies that the model s predictions provide an acceptable index of sorted and non sorted patterned ground occurrence the best performance for model calibration data for both data sets was achieved by the cta however when the predictive mapping ability was explored through the evaluation data set the model accuracies of cta decreased clearly compared to the other modelling techniques for model evaluation data mars performed marginally best our results show that the digital elevation model and soil data can be used to predict relatively robustly the activity of patterned ground in fine scale in a subarctic landscape this indicates that predictive geomorphological modelling has the advantage of providing relevant and useful information on earth surface processes over extensive areas such data being unavailable through more conventional survey methods

paleogene plants fractionated carbon isotopes similar to modern plants the carbon isotope composition 13c 13c of terrestrial plant biomarkers such as leaf waxes and terpenoids provides insights into past carbon cycling the 13c 13c values of modern plant biomarkers are known to be sensitive to climate and vegetation type both of which influence fractionation during lipid biosynthesis by altering plant carbon supply and its biochemical allocation it is not known if fractionation observed in living plants can be used to interpret fossil lipids because plant biochemical characteristics may have evolved during the cenozoic in response to changes in global climate and atmospheric co2 the goal of this study was to determine if fractionation during photosynthesis leaf leaf in the paleogene was consistent with expectations based on living plants to study plant fractionation during the paleogene we collected samples from eight stratigraphic beds in the bighorn basin wyoming usa that ranged in age from 63 to 53 ma for each sample we measured the 13c 13c of angiosperm biomarkers triterpenoids and n alkanes and abundance permitting conifer biomarkers diterpenoids leaf 13c 13c values estimated from different angiosperms biomarkers were consistently 2 lower than leaf 13c 13c values for conifers calculated from diterpenoids this difference is consistent with observations of living conifers and angiosperms and the consistency among different biomarkers suggests ancient elipidelipid values were similar to those in living plants from these biomarker based 13cleaf 13cleaf values and independent records of atmospheric 13c 13c values we calculated leaf leaf these calculated leaf leaf values were then compared to leaf leaf values modeled by applying the effects that precipitation and major taxonomic group in living plants have on leaf leaf values calculated and modeled leaf leaf values were offset by less than a permil this similarity suggests that carbon fractionation in paleogene plants changed with water availability and major taxonomic group to about the same degree it does today further paleoproxy data suggest at least two of the stratigraphic beds were deposited at times when pco2pco2 levels were higher than today biomarker data from these beds are not consistent with elevated leaf leaf values possibly because plants adapted carbon uptake and assimilation characteristics to pco2pco2 changes over long timescales

influence of provenance and preservation on the carbon isotope variations of dispersed organic matter in ancient floodplain sediments 1 carbon isotope ratios of bulk organic matter in sedimentary rocks 13cdom are a potential source of paleoenvironmental information in terrestrial stratigraphic sequences however insufficient understanding of the range of depositional and post depositional controls on 13cdom values makes interpretations of these data difficult here we evaluate the effects of organic matter om provenance and preservation on 13cdom using records spanning the paleocene eocene thermal maximum petm in the bighorn basin wyoming usa as a case study we sampled sedimentary rocks spanning the petm in two well studied locations polecat bench pb and highway 16 hw16 in the bighorn basin independent carbon isotope records from biomarkers and pedogenic carbonates at these sites suggest that local shifts in plant and soil 13c values associated with the petm cie were broadly similar and were characterized by an abrupt 5 decrease followed by a plateau and a eventual return to pre petm 13c values the 13cdom records from both sites differ significantly from these reference curves in both amplitude of change and in preserving high frequency isotopic fluctuations and large isotopic anomalies superimposed on the general pattern of isotopic change through the cie for each location we separated organo mineral fractions mom concentrated macerals from 20 stratigraphic levels and analyzed the carbon isotope ratio 13c of each fraction at both sites the 13c of the fine and coarse mom differ significantly from each other and from 13cdom concentration weighted mixing of these isotopically distinct om fractions explains high resolution 13cdom fluctuations but does not explain the large isotopic anomalies observed at both sites at hw16 we identified two thermally and isotopically distinct populations of macerals interpreted as being indigenous and recycled om at this site one over total organic carbon 1 toc values correlate with 13cdom for pre petm and petm strata and both relationships converge toward the 13c of recycled om for low toc at pb macerals display homogeneous thermal maturity but the proportion of isotopically distinct vitrinite and liptinite varies between facies relationships between 1 toc and 13cdom are also present within specific stratigraphic intervals at pb but values do not converge on a single isotopic value across the sampled interval these observations are consistent with variable mixing of om fractions having different provenance mixing of exotic recycled om at hw16 and locally reworked om at pb with indigenous fresh om at both sites and explain the large anomalies observed in the 13cdom records at both sites our findings raise questions about the assumption that om in ancient sediments is indigenous and dominantly records 13c variations of local plants

atmospheric carbon dioxide linked with mesozoic and early cenozoic climate change carbon isotopes of fossil plants and model simulations suggest that atmospheric carbon dioxide levels were variable during the period 200 to 60 million years ago the large decreases in the partial pressure of co2 coincide with glaciations providing evidence against climate co2 decoupling during the mesozoic

carbon cycle perturbation in the middle jurassic and accompanying changes in the terrestrial paleoenvironment abstract carbon isotope analyses of fossil wood from the middle jurassic ravenscar group yorkshire ne england reveal a significant excursion toward light isotopic values 13c change of 3 to 4 at about the aalenian bajocian boundary 174 ma a positive carbon isotopic excursion is also shown for the middle bajocian 170 ma but is less clearly defined these isotopic patterns are very similar to the few published marine carbonate records available for this time in particular one based on belemnites from the hebrides basin nw scotland and others from pelagic limestones in italy the similarity of the terrestrial and marine isotope curves is an indication that the observed isotopic signal is a global phenomenon through parts of the ravenscar group the scarborough formation supplementary data from bulk organic carbon and palynofacies analysis confirm that isotopic curves based on bulk analyses may be strongly influenced by the balance of terrestrial versus marine organic matter present in th

resources of gold in phanerozoic epithermal deposits we have estimated earth s endowment of gold in phanerozoic epithermal deposits using a tectonic diffusion model which simulates the emplacement of deposits at a shallow crustal depth and their subsequent vertical tectonic migration in the crust the calculation was calibrated by least squares comparison of a calculated age frequency distribution to the age frequency distribution for 448 epithermal deposits of phanerozoic age results indicate that 17 percent of the epithermal deposits that formed through phanerozoic time remain in the crust today whereas 83 percent have been removed by erosion assuming a similar age distribution for all 1 181 epithermal deposits in our compilation indicates that 307 000 deposits formed throughout phanerozoic time that 63 000 of these remain in the crust and that 244 000 have been eroded grade and tonnage data of gold in 757 epithermal deposits in the compilation have an arithmetic average of 34 7 t and yield an estimate of 2 2 106 t of gold for epithermal deposits remaining in the crust using the model based vertical distribution of deposits remaining in the crust we estimate that epithermal deposits in the upper kilometer of the united states contain 2 9 104 t of gold adjusting for areas of outcropping volcanic rocks in each continent increases our estimate to 4 0 104 t these estimates are similar to the 1 7 104 t gold resource estimated by the u s geological survey using completely different methods several comparisons based on these results provide insights into the efficiency of processes that form epithermal deposits and the outlook for sustainability for instance all of the epithermal deposits that formed through phanerozoic time represent only about 0 03 percent of the gold in the crust only about 0 007 percent of crustal gold remains in epithermal deposits the rest has been eroded and recycled this is consistent with comparisons based on the flux of gold in the taupo volcanic zone which indicate that epithermal deposits trap only 0 1 to 0 2 percent of the gold that moves through convergent margin hydrothermal systems epithermal gold deposits that remain in the crust can supply current production from them for 1 400 to 5 000 years depending on success of exploration and depth of mining finally we are consuming gold from epithermal deposits about 17 000 times faster than earth is replenishing the supply

late pleistocene glaciation of the kleiner arbersee area in the bavarian forest south germany abstract during pleistocene mountain glaciation of the bavarian forest south germany the wurmian kleiner arbersee glacier left behind glacial landforms and sediments which are described classified and interpreted using a combination of geomorphological sedimentological pedological surveying and absolute dating methods the latest kleiner arbersee glacier with a maximum length of 2600 m a minimum width of 800 m and a thickness of 115 m formed an elongated cirque four lateral moraines one divided end moraine one recessional moraine a proglacial lake and a basin in which lake kleiner arbersee was established after deglaciation beyond the glacial limit the landscape is denuded by periglacial slope deposits which are differentiated from the glacigenic sediments based upon clast fabrics clast shapes and sediment consolidation within the glacial limit sandy gravelly to silty gravelly tills are widely distributed whereas glaciolacustrine sediments are restricted to a small area north of the lake small variations in the sand and silt fraction of the tills are explained by melt out processes quartz mica and chlorite derived from gneiss bedrock are dominant in the clay mineral spectrum of tills but also gibbsite as a product of pre pleistocene weathering is present giving evidence of glacially entrained saprolites an irsl date of glaciolacustrine sediments 32 4 9 4 ka bp confirms the wurmian age for the glaciation and radiocarbon ages of the basal sediments 12 3 0 4 and 12 5 0 2 ka bp uncalibrated in the lake kleiner arbersee prove that the basin was ice free before the younger dryas

geomorphometric feature analysis using morphometric parameterization and artificial neural networks this paper presents a semi automatic method using an unsupervised neural network to analyze geomorphometric features as landform elements the shuttle radar topography mission srtm provided detai

integrating airborne multispectral imagery and airborne lidar data for enhanced lithological mapping in vegetated terrain practical and financial constraints associated with traditional field based lithological mapping are often responsible for the generation of maps with insufficient detail and inaccurately located contacts in arid areas with well exposed rocks and soils high resolution multi and hyperspectral imagery is a valuable mapping aid as lithological units can be readily discriminated and mapped by automatically matching image pixel spectra to a set of reference spectra however the use of spectral imagery in all but the most barren terrain is problematic because just small amounts of vegetation cover can obscure or mask the spectra of underlying geological substrates the use of ancillary information may help to improve lithological discrimination especially where geobotanical relationships are absent or where distinct lithologies exhibit inherent spectral similarity this study assesses the efficacy of airborne multispectral imagery for detailed lithological mapping in a vegetated section of the troodos ophiolite cyprus and investigates whether the mapping performance can be enhanced through the integration of lidar derived topographic data in each case a number of algorithms involving different combinations of input variables and classification routine were employed to maximise the mapping performance despite the potential problems posed by vegetation cover geobotanical associations aided the generation of a lithological map with a satisfactory overall accuracy of 65 5 and kappa of 0 54 using only spectral information moreover owing to the correlation between topography and lithology in the study area the integration of lidar derived topographic variables led to significant improvements of up to 22 5 in the overall mapping accuracy compared to spectral only approaches the improvements were found to be considerably greater for algorithms involving classification with an artificial neural network the kohonen self organizing map than the parametric maximum likelihood classifier the results of this study demonstrate the enhanced capability of data integration for detailed lithological mapping in areas where spectral discrimination is complicated by the presence of vegetation or inherent spectral similarities

supervised landform classification of northeast honshu from dem derived thematic maps this paper proposes a quantitative method to classify landforms using four morphometric parameters from dem derived thematic raster maps of slope and topographic openness because the different surficial processes and stages in the evolution of slopes create landscapes with different shapes these parameters may lead to a genetic interpretation of topography the raster maps of slope and topographic openness were constructed for northeast honshu japan from 50 m dems the mean and standard deviation of morphometric parameters within a 3050m by 3050m moving window on the raster maps were calculated the results for some training areas show that constructional depositional and erosional landforms with different relief have different morphometric characteristics a supervised landform classification for northeast honshu using the knowledge from the training areas revealed a ladder geomorphological structure composed of high mountains ranges and volcanoes the close relationship between the ladder geomorphological structure and volcano distribution indicates that the structure reflects the magmatic plumbing system from the upper mantle to the crust of the northeast honshu arc

multistage gold mineralization at the lapa mine abitibi subprovince insights into auriferous hydrothermal and metasomatic processes in the cadillac larder lake fault zone the lapa gold deposit contains reserves of 2 4 mt at 6 5 g t au and is one of the few deposits located directly within the cadillac larder lake fault zone cllfz a first order crustal scale fault that separates the archean abitibi subprovince from the pontiac subprovince to the south gold mineralization is predominantly hosted in highly strained and altered upper greenschist lower amphibolite facies mafic to ultramafic rocks of the piche group auriferous ore zones consist of finely disseminated auriferous arsenopyrite pyrrhotite pyrite and native gold disseminated in biotite and carbonate altered wall rocks native gold which is also present in quartz dolomite calcite veinlets is locally associated with sb bearing minerals especially at depth 1 km from surface where the deposit is characterized by a au sb as association at vertical depth greater than 1 km gold is associated with arsenopyrite and pyrrhotite au as association the mineralogy and paragenesis of the lapa deposit metamorphosed ore and alteration assemblages record the superposition of three metamorphic episodes m1 m2 and m3 and three gold mineralizing events spatial association between biotitized wall rocks and auriferous arsenopyrite indicates that arsenopyrite precipitation is concomitant with potassic alteration the predominant au as association recognized across the deposit is related to gold in solid solution in arsenopyrite as part of a pre m2 low grade auriferous hydrothermal event however the occurrence of hornblende oligoclase porphyroblasts overprinting the biotite alteration and the presence of porous clusters and porphyroblasts of arsenopyrite with native gold and pyrrhotite indicate an auriferous metasomatic event associated with peak m2 prograde metamorphism late retrograde metamorphism m3 overprints the hornblende oligoclase m2 assemblage within the host rocks proximal to ore by an actinolite albite assemblage by precipitation of free gold and sb sulfosalts at lower p t the complex relationships between ore structural features and metamorphic assemblages at lapa are related to the tectonometamorphic evolution of the cadillac larder lake fault zone at different times and crustal levels and varying heat and fluid flow regimes the lapa deposit demonstrates that early low grade gold mineralization within the cadillac larder lake fault zone has benefited from late gold enrichment s during prograde and retrograde metamorphism suggesting that multi stage processes may be important to form gold rich orogenic deposits in first order crustal scale structures

remote sensing and gis investigation of glacial features in the region of devil s lake state park south central wisconsin usa abstract this study utilizes landsat tm aster and synthetic aperture radar sar derived dems in conjunction with geographic information systems gis in order to reevaluate previously published interpretations of glacial landforms in and around devil s lake state park south central wisconsin usa devil s lake sits in a gorge carved into the southern flank of a doubly plunging syncline known as the baraboo hills through which the wisconsin or some other river flowed prior to the last ice age during the last glacial maximum about 18 000 b p an outlet glacier of the laurentide ice sheet called the green bay lobe extended southward into south central wisconsin and left behind extensive glacial landforms such as moraines drumlins and eskers during advance of the green bay lobe into the region devil s lake gorge was plugged at both ends by glacial deposits and resulted in formation of devil s lake the wisconsin river if it originally flowed through devil s lake gorge found a new course to the east of the baraboo hills syncline this study utilizes the aforementioned remote sensing data to spatially image the following features 1 original extent of the green bay lobe 2 moraines and streamlined glacial landforms as indicators of ice flow directions and 3 former path of the old wisconsin or some other river prior to being rerouted by the green bay lobe gis analysis is also performed in order to test published interpretations of the regional glacial history this study confirms that glacial features observed today are consistent with the former advance of the green bay lobe into the area formation of glacial lake wisconsin plugging of devil s lake gorge by a moraine to form devil s lake and subsequent glacial retreat leading to the breaching of an ice dam and catastrophic flooding by 14 000 years ago the large aerial coverage of satellite imagery with resolutions up to 15 m are valuable for reevaluating regional interpretations previously based on local field mapping and aerial photography of limited extent

numerical modeling of valley glacier stagnation as a paleoclimatic indicator stagnation of the terminal region of a glacier occurs in response to sufficiently large and rapid climatic warming so the presence of stagnation deposits provides quantitative information on the climate change that forced retreat here we use a simple flow line glacier model to investigate the relationship between stagnation climate forcing and aspects of the glacier bed for climatic warming greater than the threshold to cause stagnation larger or faster warming events cause longer regions of a glacier to stagnate smaller or slower warming episodes below the threshold for stagnation cause retreat while active flow persists along the entire glacier length the threshold for stagnation depends not only on the climatic forcing but also on many other aspects of the glacier with stagnation favored by factors including a lower mean bed slope with greater roughness quantitative determination of the climatic forcing consistent with the occurrence or absence of stagnation deposits requires that these site specific characteristics be incorporated in modeling

elementary forms for land surface segmentation the theoretical basis of terrain analysis and geomorphological mapping abstract land surface morphology is fundamental to geomorphological mapping and many gis applications review and comparison of various approaches to segmentation of the land surface reveals common features and permits development of a broad theoretical basis for segmentation and for characterization of segments and their boundaries within the context of defining landform units that maximise internal homogeneity and external differences this paper introduces the concept of elementary forms segments units defined by constant values of fundamental morphometric properties and limited by discontinuities of the properties the basic system of form defining properties represents altitude and its derivatives constant values of which provide elementary forms with various types of homogeneity every geometric type of elementary form can be characterized by a defining function which is a specific case of the general polynomial fitted function various types of boundary discontinuity and their connections and transformations into other types of morphological unit boundaries are analysed the wealth of types of elementary forms and their boundaries is potentially unbounded and thus is sufficient to cover the real variety of landforms elementary forms in the basic set proposed here have clear potential for genetic and dynamic interpretation a brief worked example documents the possibility of analytical computation of various models of ideal elementary forms for particular segments of landform ideal elementary forms can be considered as attractors to which the affinity of surface segments can be measured by multivariate statistical methods the use of the concept of elementary forms in landscape segmentation is promising and it could be adapted for elementary segmentation of various other spatial fields

influence of method selection on clustering analyses of point like features examples from three zones of distributed volcanism abstract most regions that have experienced spatially distributed volcanism also present a clustered structure of eruptive vents attempts to identify patterns from the spatial distribution of vents have resorted to various methods the influence that specific methods might have on the identified patterns however has remained largely unexplored in this work i assess the ability of common out of the box algorithms to yield consistent results the geological significance of those groupings is also tested the results of those tests indicate that method selection exerts a strong influence and therefore introduces undesired biases on the identification of groups on zones of distributed volcanism the results reported below indicate that it is almost impossible to capture the fine structure of volcanic clusters by focusing on a single value that best describes spatial distribution nevertheless an alternative approach that could reduce the negative influence of such method dependence is outlined this method searches for core groups as the membership identified on each group by more than one algorithm despite the limited ability of this method to reproduce pre existing geologic or tectonic partitions it provides grounds for a more robust interpretation of results than the use of only one out of the box method in isolation