forearc strike slip displacement as an alternative to subduction erosion with examples from mexico and california sinistral nacimiento fault slip on the nacimiento fault of the central coast ranges of california has been variably interpreted as dextral sinistral or reverse the currently prevailing interpretation is that the nacimient

comparing physiographic maps with different categorisations abstract this paper addresses the need for a robust map comparison method suitable for finding similarities between thematic maps with different forms of categorisations in our case the requirement was to establish the information content of newly derived physiographic maps with regards to set of reference maps for a study area in england and wales physiographic maps were derived from the 90 m resolution srtm dem using a suite of existing and new digital landform mapping methods with the overarching purpose of enhancing the physiographic unit component of the soil and terrain database soter reference maps were seven soil and landscape datasets mapped at scales ranging from 1 200 000 to 1 5 000 000 a review of commonly used statistical methods for categorical comparisons was performed and of these the cramer s v statistic was identified as the most appropriate for comparison of maps with different legends interpretation of multiple cramer s v values resulting from one by one comparisons of the physiographic and baseline maps was facilitated by multi dimensional scaling and calculation of average distances between the maps the method allowed for finding similarities and dissimilarities amongst physiographic maps and baseline maps and informed the recommendation of the most suitable methodology for terrain analysis in the context of soil mapping

nd sr isotopic geochemical and petrographic stratigraphy and paleotectonic analysis mesozoic great valley forearc sedimentary rocks of california measurements of nd sr isotopes major and trace elements and model mineralogy were made on upper jurassic and cretaceous great valley forearc sedimentary rocks to test models for the temporal and spatial evolution of sierra nevada arc sources isotopes and major and trace elements are sensitive provenance indicators because of the large west east isotopic geochemical and age gradients in the plutonic rocks of the sierra nevada batholith and because petrographic models indicate that source areas moved east during the cretaceous isotopic and chemical variations are correlated in the forearc sandstone as nd decreases th u la nb zr hf pb rb sio2 and k2o concentrations increase and feo mgo tio2 ni and cr concentrations decrease this relation is the same as that observed in the plutonic rocks and indicates that the arc was the primary source of sediment and that the sandstone chemistry was not disturbed by sedimentary processes the nd sr relation of san joaquin valley sandstone is the same as the plutonic rocks but sacramento valley sandstone is elevated in sr because of seawater exchange weathering and diagenesis whole rock sandstone decreases in nd from 7 to 5 and increases in 87sr 86sr from 0 7045 to 0 7073 with decreasing stratigraphic age the nd sr isotopic composition is correlative with the plagioclase to feldspar ratio and indicates that source areas moved inland during the cretaceous upper cretaceous san joaquin valley shale is similar in nd to the sandstone indicating that sandstone and shale were derived from the same source and that the nd isotopic composition is independent of grain size the shale is higher in 87sr 86sr than the sandstone possibly due to concentration of biotite in the fine fraction during transport and subsequent rb loss during diagenesis nd sr isotopes were used to construct models to locate source areas parameters include lithology drainage basin geometry and erosion rate the age and isotopic compositions of the calculated igneous component of the sandstone correspond to the age and isotopic compositions of the plutonic rocks of the batholith this correspondence indicates that 1 the isotopic composition of the plutonic rocks and the coeval volcanic cover were similar 2 the volcanic front was denuded within a few million years and 3 the sediment was derived from the head of the drainage basin located at the migrating volcanic front

crustal structure of the java margin from seismic wide angle and multichannel reflection data seismic investigations across the convergent sunda margin off indonesia provide a detailed image of the crustal architecture of the sunda plate boundary the combined analysis and interpretation of wide angle and reflection seismic data along two coincident profiles across the subduction zone are complemented by additional lines within the forearc domain which yield some three dimensional 3 d constraints on the velocity depth structure across the margin a detailed cross section of the subduction zone is presented which is confirmed by supplementary gravity modeling the sunda convergence zone is a prime example of an accretionary margin where sediment accretion has led to the formation of a massive accretionary prism with a total width of 110 km between the trench and the forearc basin it is composed of a frontal wedge which documents ongoing accretion and a fossil part behind the present backstop structure which constitutes the outer high moderate seismic velocities derived from wide angle modeling indicate a sedimentary composition of the outer high the subducting oceanic slab is traced to a depth of almost 30 km underneath the accretionary prism the adjacent forearc domain is characterized by a pronounced morphological basin which is underlain by a layer of increased seismic velocities and a shallow upper plate moho at 16 km depth we speculate that remnant fragments of oceanic crust might be involved in the formation of this oceanic type crust found at the leading edge of the upper plate beneath the forearc basin

detrital zircon evidence for progressive underthrusting in franciscan metagraywackes west central california we present new u pb ages for detrital zircons separated from six quartzose metagraywackes collected from different franciscan complex imbricate nappes around san francisco bay all six rocks contain a broad spread of late jurassic cretaceous grains originating from the klamath sierra nevada volcanic plutonic arc units young structurally downward consistent with models of progressive underplating and offscraping within a subduction complex the youngest specimen is from the structurally lowest san bruno mountain sheet at 52 ma it evidently was deposited during the eocene none of the other metagraywackes yielded zircon ages younger than 83 ma zircons from both el cerrito units are dominated by ca 100 160 ma grains the upper el cerrito also contains several grains in the 1200 1800 ma interval these samples are nearly identical to 97 ma metasedimentary rock from the hunters point shear zone zircon ages from this melange block exhibit a broad distribution ranging from 97 to 200 ma with only a single pre mesozoic age the albany hill specimen has a distribution of pre mesozoic grains from 1300 to 1800 ma generally similar to that of the upper el cerrito sheet however it contains zircons as young as 83 ma suggesting that it is significantly younger than the upper el cerrito unit the skaggs spring schist is the oldest studied unit its youngest analyzed grains were ca 144 ma and it is the only investigated specimen to display a significant paleozoic detrital component sedimentation and subduction accretion of this tract of the trench complex took place along the continental margin during early to early late cretaceous time and perhaps into eocene time franciscan and great valley deposition attests to erosion of an andean arc that was active over the entire span from ca 145 to 80 ma with an associated accretionary prism built by progressive underthrusting we use these new data to demonstrate that the eastern franciscan complex in the northern and central coast ranges is a classic accretionary prism where younger structurally lower allochthons are exposed on the west and older structurally higher allochthons occur to the east in the heavily studied san francisco bay area

birth death and resurrection the life cycle of suprasubduction zone ophiolites 1 suprasubduction zone ssz ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites this sequence includes the following 1 birth which entails the formation of the ophiolite above a nascent or reconfigured subduction zone this stage is typically characterized by the eruption of arc tholeiite lavas and the formation of layered gabbros and sheeted dike complex 2 youth during which is continued melting of refractory asthenosphere depleted during birth occurs in response to fluid flux from the subducting slab with extensional deformation of the older plutonic suite eruption of refractory lavas and the intrusion of wehrlite pyroxenite 3 maturity with the onset of semistable arc volcanism typically calc alkaline as the subduction zone matures and stabilizes and the intrusion of quartz diorite and eruption of silicic lavas and 4 death which is the sudden demise of active spreading and ophiolite related volcanism which in many cases is linked to collision with an active spreading center and the onset of shallow underthrusting of the buoyant spreading axis expressed as dikes and lavas with oceanic basalt compositions that crosscut or overlie rocks of the older suites 5 resurrection with emplacement by obduction onto a passive margin or accretionary uplift with continued subduction the early stages 1 3 may be diachronous and each stage may overlap in both time and space the existence of this consistent progression implies that ophiolite formation is not a stochastic event but is a natural consequence of the ssz tectonic setting

geomorphometry and landform mapping what is a landform abstract starting from a concept of the land surface its definition and subdivision from digital elevation models dems is considered high resolution dems from active remote sensing form a new basis for geomorphological work which is moving on from consideration of whether data are accurate enough to how the surface of interest can be defined from an overabundance of data discussion of the operational definition and delimitation of specific landforms of varying degrees of difficulty from craters to mountains is followed by the applicability of fuzzy boundaries scaling usually allometric is shown to be compatible with the scale specificity of many landforms this is exemplified by glacial cirques and drumlins classification of a whole land surface is more difficult than extraction of specific landforms from it well dissected fluvial landscapes pose great challenges for areal analyses these are tackled by the delimitation of homogeneous elementary forms and or land elements in which slope position is considered the boundaries are mainly breaks in gradient or aspect but may also be in some type of curvature breaks in altitude are rare elementary forms or land elements are grouped together into functional regions landforms such as hill sheds it may often be useful to recognise fuzziness of membership or core and periphery of a surface object plains and etched or scoured surfaces defy most of these approaches and general geomorphometry remains the most widely applicable technique it has been applied mainly within arbitrary areas and to some extent to drainage basins but more experimentation with mountain ranges and other landforms or landform regions is needed geomorphological mapping is becoming more specialised and its legends are being simplified its incorporation into geographical information systems gis has required greater precision with definitions and the separation of thematic layers so that it is converging with specific geomorphometry and becoming more flexible and more applicable with a broader range of visualisation techniques

gas and water geochemistry of geothermal systems in dominica lesser antilles island arc abstract four of the nine potentially active volcanoes on the island of dominica in the lesser antilles volcanic island arc have associated active volcanic hydrothermal systems between 2000 and 2006 the gas and thermal waters from these systems were investigated to geochemically characterise the fluids gain insight into the temperature and equilibrium state of the underlying reservoirs and evaluate the feasibility of monitoring geothermal features as a volcano surveillance tool in dominica the geothermal gases are typical of those found in arc type settings with n2 excess and low amounts of he and ar the dry gas is dominated by co2 ranging from 492 to 993 mmol mol and has a hydrothermal signature with hydrogen sulphide as the main sulphurous gas the waters are predominantly acid sulphate so4 100 4200 mg l ph 4 and likely formed as a result of dilution of acidic gases in near surface oxygenated groundwater enrichment in both 18o and d with respect to the global meteoric water line gmwl confirms that the waters are of primarily meteoric origin but have been affected by evaporation processes quartz geothermometers gave equilibrium temperatures of 83 c 203 c these temperatures contrast with the higher equilibrium temperature ranges 170 c 350 c obtained for the gases using the h2 ar ch4 co2 gas ratios plot suggesting that the quartz geothermometers are affected by non attainment of equilibrium this may be a result of precipitation of the dissolved silica and or dilution by relatively cold shallow aquifers of the thermal fluids generally no significant variations in fluid gas chemistry of the hydrothermal systems were observed during the study period and we propose that there were no changes in the state of volcanic activity in this period one exception to this occurred in a feature known as the boiling lake which underwent a month long period of significant compositional temperature and water level fluctuations ascribed to a drastic decrease of hydrothermal input related to a perturbation in the lake probably seismically induced this geochemical study is part of an ongoing monitoring programme of dominica geothermal systems aimed at establishing long term geochemical observations for the purpose of volcano monitoring

nappes tectonics of oblique plate convergence and metamorphic evolution related to 140 million years of continuous subduction franciscan complex california this paper presents a new synthesis of franciscan complex tectonics with the emphasis on the pre san andreas fault history of these rocks field relations suggest that the franciscan is characterized by nappe structures that formed during sequential accretion at the trench the presence of these structures along with other field relations including the lack of evidence for large offset of conglomerate suites indicates that strike slip fault systems of large displacement 500 km did not cut the franciscan complex during subduction regional geology and comparisons to modern arc trench systems suggest that strike slip faulting associated with oblique subduction took place inboard east of the franciscan in the vicinity of the magmatic arc the franciscan varies along strike because individual accreted elements packets of trench sediment seamounts etc did not extend the full length of the trench different depths of underplating distribution of post metamorphic faulting and level of erosion pro

geodynamic mechanism and classification of basins in the earth system abstract the sedimentary basin is a basic geological unit in the earth system its formation and evolution are controlled mainly by plate tectonics and geodynamics which have produced a variety of basin types the development and evolution of various basins depend not only on the tectonic effect of lithospheric plate but also on sublithospheric and earth surface actions basin classification schemes based on the theories of platform geosyncline or plate tectonics could neither include all basin types nor reflect the complex processes of basin formation and evolution from the viewpoint of earth system we proposed a new basin classification scheme based on geodynamic mechanism that is lithospheric plate sublithospheric and earth surface actions in our geodynamic classification we employed a series of geodynamic settings of basin formation and evolution including the lithospheric plate sublithospheric and earth surface environments the dynamic regimes of basin formation and evolution such as tectonic setting extension compression and shearing the thermal processes and gravity effects the various natures of basin basement and crustal types continental oceanic or transitional crust and the history of basin sedimentary filling and tectonic paleogeography successively as the controlling factors for basin classification this new geodynamic classification scheme highlights both the role of the lithosphere and the effects of the sublithospheric and the earth surface actions on controlling the basin formation and evolution the basic dynamic types of basin classification include the prototype basin forming under a single tectonic thermal or gravity regime and the superimposed basin as well as residual basin forming under multistage thermal and or tectonic regimes thus this classification scheme could provide an evolving understanding of lithosphere crust mantle interaction and geodynamic processes as well as of hydrocarbon accumulation and metallogenic mechanisms in sedimentary basins and would help in the synthetic exploration of various resources

water geochemistry and soil gas survey at ungaran geothermal field central java indonesia abstract a soil gas survey for radon rn thoron tn co 2 and mercury hg and the chemical analysis of hot spring waters were undertaken in the ungaran geothermal field central java indonesia the results of soil gas surveys indicate fault systems trending nne ssw and wnw ese particularly high co 2 concentrations 20 and high hg concentrations were detected in vicinity of the fumaroles emanometries of rn tn and co 2 also conclusively identified the presence of a fracture zone for the migration of geothermal fluid the hg results infer that the up flow zone of high temperature geothermal fluids maybe located in the north of fumaroles in the gedongsongo area near the collapse wall chemistry of thermal springs in the up flow zone are acid ph 4 and show a ca mg so 4 composition the thermal waters are mainly ca mg hco 3 and ca na so 4 hco 3 types near the fumarolic area and are mixed na ca cl hco 3 waters in the south east of gedongsongo the 18 o between 5 3 and 8 2 and between 39 and 52 indicate that the waters are essentially meteoric in origin a conceptual hydro geochemical model of the gedongsongo thermal waters based on the soil gas isotope and chemical analytical results was constructed

forearc basins types geometries and relationships to subduction zone dynamics forearc basins are one of the fundamental sedimentary basins and they preserve various geological phenomena arising from dynamic interactions between subducting and overriding plates along convergent plate boundaries previous studies have proposed descriptive classification schemes for such basins and performed analog experiments and numerical simulations examining basin formation and evolution however the great variability of forearc basins means that a comprehensive understanding of these features remains elusive this paper proposes a new classification scheme for forearc basins from the viewpoints of material transfer between the two plates accretionary or nonaccretionary and the long term strain field in the basin compressional or extensional by using characteristics of 41 modern forearc basins geometric characteristics were also analyzed in order to reveal the relationship to subduction zone dynamics including material transfer at the plate boundary accretion erosion plate convergence configurations and kinematics and the mechanics of strain and its partitioning compressional accretionary type basins which are characterized by landward tilting strata and the landward migration of depocenters show a constant width thickness ratio indicating self similar growth of the basin as the outer wedge builds up extensional accretionary type basins develop normal faults in the basin probably due to a gravitational instability of the outer wedge an increase of sediment flux at the trench may grow the accretionary prism and thicken the subduction channel faster leading to a reduction of basal and internal shear strengths of the outer wedge subsidence caused by crustal thinning characterizes the nonaccretionary type basins which have thin trench fill sediments large forearc slopes steady widths of the outer wedge and variable width thickness ratios of the basins from these results the sediment flux at the trench and the plate boundary can be considered as a dominant factor that determines accretion or erosion of the outer wedge and uplift or subsidence of the outer arc high and that is also responsible for the style of deposition in the forearc basin an increase or decrease of the sediment flux may change the type geometry and deformation manner of the forearc basin the results of this study provide important clues to further our understanding of dynamic interactions between forearc basins and subduction zone processes

soil gas method for tracing neotectonic faults in clay basins the pisticci field southern italy abstract two soil gas surveys were performed in 1991 and 1993 over an area of 95 km 2 at pisticci southern italy the research was aimed at assessing the relationship between soil gas distribution and fracture systems in a plio pleistocene clay basin located in the bradanic trough more than 400 samples were collected to measure the he co 2 and 222 rn concentration in soil atmosphere very large helium anomalies he up to 21 000 ppb above atmospheric reference were detected in 1991 in correspondence with the youngest fractures reported in the literature in order to verify the persistence of such soil gas anomalies a survey was conducted again in 1993 in subareas where major helium anomalies were previously detected the values of co 2 and 222 rn have shown about the same average as that in the 1991 survey while he values have revealed a sharp decrease with maximum values not exceeding 3000 ppb this considerable difference is tentatively related to the seismic activity that occurred just before the 1991 survey whereas no appreciable seismic activity was reported in 1993 the results of the soil gas surveys show that the shape and spatial distribution of the gas anomalies are related to the structural pattern of the area whereas the magnitude of gas leakage is controlled by the occurrence of deep gas bearing traps hydrocarbon reservoirs and possibly triggered by seismic activity

automated object based classification of topography from srtm data we introduce an object based method to automatically classify topography from srtm data the new method relies on the concept of decomposing land surface complexity into more homogeneous domains an elevation layer is automatically segmented and classified at three scale levels that represent domains of complexity by using self adaptive data driven techniques for each domain scales in the data are detected with the help of local variance and segmentation is performed at these appropriate scales objects resulting from segmentation are partitioned into sub domains based on thresholds given by the mean values of elevation and standard deviation of elevation respectively results resemble reasonably patterns of existing global and regional classifications displaying a level of detail close to manually drawn maps statistical evaluation indicates that most of classes satisfy the regionalization requirements of maximizing internal homogeneity while minimizing external homogeneity most objects have boundaries matching natural discontinuities at regional level the method is simple and fully automated the input data consist of only one layer which does not need any pre processing both segmentation and classification rely on only two parameters elevation and standard deviation of elevation the methodology is implemented as a customized process for the ecognition software available as online download the results are embedded in a web application with functionalities of visualization and download

climate physiographically differentiated pan european landslide susceptibility assessment using spatial multi criteria evaluation and transnational landslide information abstract with the adoption of the eu thematic strategy for soil protection in 2006 small scale 1 1 m assessments of threats affecting soils over europe received increasing attention as landslides have been recognized as one of eight threats requiring a pan european evaluation we present an approach for landslide susceptibility evaluation at the continental scale over europe unlike previous continental and global scale landslide susceptibility studies not utilizing spatial information on the events we collected more than 102 000 landslide locations in 22 european countries these landslides are heterogeneously distributed over europe but are indispensable for the evaluation and classification of pan european datasets used as spatial predictors and the validation of the resulting assessments for the analysis we subdivided the european territory into seven different climate physiographical zones by combining morphometric and climatic data for terrain differentiation and adding a coastal zone defined as a 1 km strip inland from the coastline landslide susceptibility modeling was performed for each zone using heuristic spatial multicriteria evaluations supported by analytical hierarchy processes and validated with the inventory data using the receiver operating characteristics in contrast to purely data driven statistical modeling techniques our semi quantitative approach is capable to introduce expert knowledge into the analysis which is indispensable considering quality and resolution of the input data and incompleteness and bias in the inventory information the reliability of the resulting susceptibility map elsus 1000 version 1 1 km resolution was examined on an administrative terrain unit level in areas with landslide information and through the comparison with available national susceptibility zonations these evaluations suggest that although the elsus 1000 is capable for a correct synoptic prediction of landslide susceptibility in the majority of the area it needs further improvement in terms of data used

petrofacies and provenance of late mesozoic forearc basin northern and central california data from the great valley group sequence represent the most complete information regarding sandstone petrology of sediment derived from a magmatic arc this information is useful in documenting tectonic and magmatic events within the arc and related terranes and forms the basis for the establishment of petrostratigraphic units for mapping and correlation sandstone and conglomerate compositions are controlled by changes in provenance many of which were basinwide and synchronous clay mineral composition is controlled primarily by burial metamorphism careful attention to sample collection sample preparation and petrographic techniques is essential for uniform results seven petrographic parameters p f lv l m qp q q f and l listed in decreasing importance to petrofacies discrimination define eight petrofacies stony creek platina lodoga grabast boxer cortina los gatos and rumsey listed in approximate order of decreasing age the upper jurassic lower cretaceous petrofacies stony creek platina and lodoga contain higher lithic contents supracrustal sources whereas the upper cretaceous petrofacies especially the rumsey contain higher proportions of plutoniclastic components quartz feldspar and micas the proportion of potassium feldspar increases from near zero in the upper jurassic to nearly 50 of all feldspars in the uppermost cretaceous the lower part of the great valley group upper jurassic and lower cretaceous contains significant quantities of sedimentaclastic and metamorphiclastic material eroded from accreted and deformed terranes tectonic highlands formed by the arc arc collision nevadan orogeny that occurred prior to initiation of the franciscan great valley sierra nevada arc trench system the klamath mountains area provided a major proportion of this detritus ophiolite and serpentinite detritus was deposited locally near the base of the great valley group as a result of deformation along the east side of the growing franciscan subduction complex volcaniclastic detritus was fed into the entire forearc basin as magmatism increased in the sierra nevada area during the cretaceous as the volcanic cover was stripped off plutoniclastic and metamorphiclastic detritus from the underlying batholithic terranes was provided in abundance to the forearc basin crustal components were more continental in the southern sierra nevada and more oceanic in the northern sierra nevada as demonstrated by the higher proportions of metamorphiclastic detritus and by the more felsic nature of volcaniclastic detritus to the south by the middle of the late cretaceous extensive batholithic terranes provided potassium feldspar rich arkosic detritus to the entire forearc basin by the paleogene arc magmatism had migrated eastward sufficiently that deeper levels of the california part of the arc were exposed by erosion tectonic activity decreased in the forearc basin and the basin was filled to sea leve in most parts

andean forearc dynamics as recorded by detrital zircon from the eocene talara basin northwest peru abstract eocene strata of the talara forearc basin of northwest peru contain detrital zircon dz populations that when integrated with other provenance indicators record paleogeographic shifts in the andean forearc that can be linked to larger scale tectonic drivers such as subduction erosion plate convergence rate and regional accretion events because forearc basins along the western margin of south america are particularly difficult to preserve the new dz results provide rare insight into the trench arc dynamics associated with the andean orogenic cycle the talara basin tapped into both the andean volcanic arc and older basement and the dz populations subsequently reflect long lived plate interactions and progressive crustal growth along the northwestern edge of amazonia gondwana and south america dominant u pb zircon age populations include 36 110 ma andes convergence 215 285 ma western gondwana extension 460 625 ma rodinia extension and western gondwana convergence 950 1250 ma grenville orogeny and 1250 ma amazonia assembly the data corroborate previous geochronology on pre andean basement and support the existence of a famatinian arc 480 ma and carboniferous triassic magmatism along northwestern gondwana pre andean and amazonian dz likely was recycled from paleozoic metasedimentary rocks of the andean cordillera and amotape terrane although the data do not preclude delivery of amazonian detritus directly into the forearc via a large scale westward drainage the andean dz population constrains the timing of arc activity and quiescence with two peaks at 75 ma and 50 ma and a gap at 70 ma linked to accretion of the caribbean oceanic plateau against northwest south america arc volcanism was concurrent with eocene forearc deposition and syndepositional dz is used to revise maximum depositional age for the upper eocene helico member and verdun formation progressive subsidence and arc shut down in the late eocene coincide with arc collision to the north uplift of the amotape block subduction erosion and slab shallowing

chemical and isotopic changes in the hydrology of the tauhara geothermal field due to exploitation at wairakei abstract depressurisation of the tauhara field due to massive withdrawal of deep chloride water from the adjacent wairakei field for geothermal power has caused considerably hydrological and chemical changes at tauhara in the undisturbed state 1962 deep chloride water discharged as hot and boiling dilute chloride springs on the east and west flanks of the field the terrace and spa areas respectively while steam from the two phase zone of the deep system produced by absorption into near surface groundwater steam heated sulphatebicarbonate waters and by mixing with chloride water chloride sulphate waters by 1978 1981 the chloride waters had stopped discharging on the western flank the steam flow towards the surface had greatly increased by 5 10 fold increasing the volume and temperature of the steam heated waters but the dilute chloride waters of the terrace area had changed very little silica concentrations in the near surface waters appear to be controlled by the solubility of amorphous silica which is present in the surface zone rocks e g taupo pumice breccias the increased steam flow led to enrichment in the 13 o and d contents of the steam heated waters by loss of secondary steam and enlargement of the area and intensity of steaming ground the latter accompanied by hydrothermal eruptions in 1974 and 1981 generation of the steam heated waters has been modelled using mass heat and isotope balances the model is consistent with observed heat and cold groundwater flows and requires that a large proportion of the heat from adsorbed primary steam is released as secondary steam tritium contents show that the steam heated waters have a mean residence time of 50 100 years in the future invasion of the deep system by cooler surface waters may reduce steam flow and lower surface aquifer temperatures

compositions and flux of soil gas in liu huang ku hydrothermal area northern taiwan abstract soil co 2 flux has been considered a useful proxy to remotely monitor volcanic activity in a hydrothermal area within a safe distance the liu huang ku lhk area which is close to the taipei basin and many existing active fumaroles and hot springs was chosen for the first systematic soil gas study in a hydrothermal area of taiwan in 2004 and 2006 the soil co 2 flux was measured by the closed chamber method with a non dispersive infrared detector soil co 2 emission rate was estimated 19 8 0 2 t day 1 and 582 t km 2 day 1 in 2004 and 22 4 0 2 t day 1 and 659 t km 2 day 1 in 2006 respectively these values are close to those reported for other active high co 2 flux hydrothermal areas of the world it implies that magmatic gases are actively degassing from subsurface in northern taiwan helium and carbon isotopic data reveal that soil gas in lhk is mainly derived from the mantle and is mixed with a small amount of crustal and air components the abundance of soil co 2 shows a positive correlation with the 3 he 4 he ratios and total sulfur contents which are considered as magmatic sensitive indicators for the fumarolic samples therefore soil co 2 could be used as a good proxy for future monitoring of magmatic activity in this area

object oriented identification of forested landslides with derivatives of single pulse lidar data in contrast to the many studies that use expert based analysis of lidar derivatives for landslide mapping in forested terrain only few studies have attempted to develop semi automatic methods for extracting landslides from lidar derivatives while all these studies are pixel based it has not yet been tested whether object oriented analysis ooa could be an alternative this study investigates the potential of ooa using only single pulse lidar derivatives such as slope gradient roughness and curvature to map landslides more specifically the focus is on both lidar data segmentation and classification of slow moving landslides in densely vegetated areas where spectral data do not allow accurate landslide identification a multistage procedure has been developed and tested in the flemish ardennes belgium the procedure consists of 1 image binarization and multiresolution segmentation 2 classification of landslide parts main scarps and landslide body segments and non landslide features i e earth banks and cropland fields with supervised support vector machines at the appropriate scale 3 delineation of landslide flanks 4 growing of a landslide body starting from its main scarp and 5 final cleaning of the inventory map the results obtained show that ooa using lidar derivatives allows recognition and characterization of profound morphologic properties of forested deep seated landslides on soil covered hillslopes because more than 90 of the main scarps and 70 of the landslide bodies of an expert based inventory were accurately identified with ooa for mountainous areas with bedrock on the other hand creation of a transferable model is expected to be more difficult

morphological characterisation of reef types in torres strait and an assessment of their carbonate production coral reefs represent major accumulations of calcium carbonate caco3 the particularly labyrinthine network of reefs in torres strait north of the great barrier reef gbr has been examined in order to estimate their gross caco3 productivity the approach involved a two step procedure first characterising and classifying the morphology of reefs based on a classification scheme widely employed on the gbr and then estimating gross caco3 productivity rates across the region using a regional census based approach this was undertaken by independently verifying published rates of coral reef community gross production for use in torres strait based on site specific ecological and morphological data a total of 606 reef platforms were mapped and classified using classification trees despite the complexity of the maze of reefs in torres strait there are broad morphological similarities with reefs in the gbr the spatial distribution and dimensions of reef types across both regions are underpinned by similar geological processes sea level history in the holocene and exposure to the same wind wave energetic regime resulting in comparable geomorphic zonation however the presence of strong tidal currents flowing through torres strait and the relatively shallow and narrow dimensions of the shelf exert a control on local morphology and spatial distribution of the reef platforms a total amount of 8 7million tonnes of caco3 per year at an average rate of 3 7kg caco3m 2yr 1 g were estimated for the studied area extrapolated production rates based on detailed and regional census based approaches for geomorphic zones across torres strait were comparable to those reported elsewhere particularly values for the gbr based on alkalinity reduction methods however differences in mapping methodologies and the impact of reduced calcification due to global trends in coral reef ecological decline and changing oceanic physical conditions warrant further research the novel method proposed in this study to characterise the geomorphology of reef types based on classification trees provides an objective and repeatable data driven approach that combined with regional census based approaches has the potential to be adapted and transferred to different coral reef regions depicting a more accurate picture of interactions between reef ecology and geomorphology

a new digital bathymetric model of the south china sea based on the subregional fusion of seven global seafloor topography products abstract an understanding of ocean bathymetry is important in marine planning navigation military activities and environmental monitoring the fusion of spatial data such as those from multi source digital bathymetric models dbms can effectively improve the efficiency of large scale seafloor topographical research and the accuracy of the results obtained therein on the one hand with the release of 15arc seconds resolution dbms it is now necessary to verify the quality of these new products on the other hand in order to generate a new high quality seamless dbm in the south china sea scs and adjacent areas an adaptive subregional spatial domain weighted fusion framework is proposed first seven of the most widely used global dbms are selected and multi source subregional measured depth sounding data undergo data cleaning and other preprocessing next based on the homogeneity of the terrain features an adaptive subregional topographical analysis is performed and the subregional data are weight fused finally the fusion dataset is post processed via model smoothing and other procedures in addition the advantages and limitations of the dbms of the scs are compared the results show that srtm15 plus v2 is the most reliable of the original dbms the updated seamless scs dbm is void free and more similar to srtm15 plus v2 with a resolution of 15arc seconds the root mean square error rmse of the new model is 99 60 m its accuracy is 13 40 15 and 1 higher than those achieved by the gebco 2019 gebco 2014 srtm30 plus and srtm15 plus models respectively and its expression of the topography is more detailed and realistic the feasibility and limitations of the proposed fusion framework are demonstrated the present findings provide a useful reference for the timely reconstruction and updating of large scale seafloor topography from multiple datasets

local variance for multi scale analysis in geomorphometry increasing availability of high resolution digital elevation models dems is leading to a paradigm shift regarding scale issues in geomorphometry prompting new solutions to cope with multi scale analysis and detection of characteristic scales we tested the suitability of the local variance lv method originally developed for image analysis for multi scale analysis in geomorphometry the method consists of 1 up scaling land surface parameters derived from a dem 2 calculating lv as the average standard deviation sd within a 3 3 moving window for each scale level 3 calculating the rate of change of lv roc lv from one level to another and 4 plotting values so obtained against scale levels we interpreted peaks in the roc lv graphs as markers of scale levels where cells or segments match types of pattern elements characterized by relatively equal degrees of homogeneity the proposed method has been applied to lidar dems in two test areas different in terms of roughness low relief and mountainous respectively for each test area scale levels for slope gradient plan and profile curvatures were produced at constant increments with either resampling cell based or image segmentation object based visual assessment revealed homogeneous areas that convincingly associate into patterns of land surface parameters well differentiated across scales we found that the lv method performed better on scale levels generated through segmentation as compared to up scaling through resampling the results indicate that coupling multi scale pattern analysis with delineation of morphometric primitives is possible this approach could be further used for developing hierarchical classifications of landform elements

automated classifications of topography from dems by an unsupervised nested means algorithm and a three part geometric signature abstract an iterative procedure that implements the classification of continuous topography as a problem in digital image processing automatically divides an area into categories of surface form three taxonomic criteria slope gradient local convexity and surface texture are calculated from a square grid digital elevation model dem the sequence of programmed operations combines twofold partitioned maps of the three variables converted to greyscale images using the mean of each variable as the dividing threshold to subdivide increasingly subtle topography grid cells sloping at less than mean gradient of the input dem are classified by designating mean values of successively lower sloping subsets of the study area nested means as taxonomic thresholds thereby increasing the number of output categories from the minimum 8 to 12 or 16 program output is exemplified by 16 topographic types for the world at 1 km spatial resolution srtm30 data the japanese islands at 270 m and part of hokkaido at 55 m because the procedure is unsupervised and reflects frequency distributions of the input variables rather than pre set criteria the resulting classes are undefined and must be calibrated empirically by subsequent analysis maps of the example classifications reflect physiographic regions geological structure and landform as well as slope materials and processes fine textured terrain categories tend to correlate with erosional topography or older surfaces coarse textured classes with areas of little dissection in japan the resulting classes approximate landform types mapped from airphoto analysis while in the americas they create map patterns resembling hammond s terrain types or surface form classes srtm30 output for the united states compares favorably with fenneman s physical divisions experiments are suggested for further developing the method the arc info aml and the map of terrain classes for the world are available as online downloads

evaluation of tandem x elevation data for geomorphological mapping and interpretation in high mountain environments a case study from se tibet china abstract digital elevation models dems are a prerequisite for many different applications in the field of geomorphology in this context the two near global medium resolution dems originating from the srtm and aster missions are widely used for detailed geomorphological studies particularly in high mountain environments these datasets are however known to have substantial disadvantages beyond their posting i e data gaps and miscellaneous artifacts the upcoming tandem x dem is a promising candidate to improve this situation by application of state of the art radar technology exhibiting a posting of 12 m and less proneness to errors in this study we present a dem processed from a single tandem x cossc scene covering a study area in the extreme relief of the eastern nyainqentanglha range southeastern tibet the potential of the resulting experimental tandem x dem for geomorphological applications was evaluated by geomorphometric analyses and an assessment of landform cognoscibility and artifacts in comparison to the aster gdem and the recently released srtm 1 dem detailed geomorphological mapping was conducted for four selected core study areas in a manual approach based exclusively on the tandem x dem and its basic derivates the results show that the self processed tandem x dem yields a detailed and widely consistent landscape representation it thus fosters geomorphological analysis by visual and quantitative means allowing delineation of landforms down to footprints of 30 m even in this premature state the tandem x elevation data are widely superior to the aster and srtm datasets primarily owing to its significantly higher resolution and its lower susceptibility to artifacts that hamper landform interpretation conversely challenges toward interferometric dem generation were identified including i triangulation facets and missing topographic information resulting from radar layover on steep slopes facing toward the radar sensor ii low coherence values on leeward slopes iii decorrelation effects over water bodies and iv challenges for phase unwrapping in settings of strong topographic contrasts there is however a high probability that these drawbacks can be overcome by applying multiple interferograms exhibiting different perpendicular baselines as planned for the generation of the final tandem x dem product

evaluation of groundwater hydrochemical characteristics and mixing behavior in the daying and qicun geothermal systems xinzhou basin this paper examines groundwater hydrochemical characteristics during mixing between thermal and non thermal groundwater in low to medium temperature geothermal fields a case study is made of daying and qicun geothermal fields in the xinzhou basin of shanxi province china the two geothermal fields have similar flow patterns with recharge sourced from precipitation in mountain areas heated through a deep cycle before flowing into overlying quaternary porous aquifers via fractures hydrochemical features of 60 ground and surface water samples were examined in the context of hydrogeologic information the average temperatures of the deep geothermal reservoirs are estimated to be 125 degrees c in daying field and 159 degrees c in qicun field based on na k mg geothermometry while slightly lower estimates are obtained using silica geothermometers hydrochemical features of thermal water are distinct from cold water thermal groundwater is mainly cl center dot so 4 na type with high tds while non thermal groundwater is mostly hcl 3 ca center dot mg and hco 3 ca type in the daying and qicun regions respectively hydrogeochemical processes are characterized by analyzing ion ratios in various waters higher contents of some minor elements in thermal waters such as f si b and sr are probably derived from extended water rock interaction and these elements can be regarded as indicators of flow paths and residence times mixing ratios between cold and thermal waters were estimated with cl na and b concentrations using a mass balance approach mixing between ascending thermal waters and overlying cold waters is extensive the proportion of water in the quaternary aquifer derived from a deep thermal source is lower in daying geothermal field than in qicun field 5 3 7 3 vs 6 3 49 3 mixing between thermal and non thermal groundwater has been accelerated by groundwater exploitation practices and is enhanced near faults shallow groundwater composition has also been affected by irrigation with low temperature thermal water c 2009 elsevier b v all rights reserved

hydrogeochemistry of the simav geothermal field western anatolia turkey thermal waters hosted by menderes metamorphic rocks emerge along fault lineaments in the simav geothermal area thermal springs and drilled wells are located in the eynal citgol and nasa locations which are part of the simav geothermal field studies were carried out to obtain the main chemical and physical characteristics of thermal waters these waters are used for heating of residences and greenhouses and for balneological purposes bottom temperatures of the drilled wells reach 163 c with total dissolved solids around 2225 mg kg surface temperatures of thermal springs vary between 51 c and 90 c all the thermal waters belong to na hco3 so4 facies the cold groundwaters are ca mg hco3 type dissolution of host rock and ion exchange reactions in the reservoir of the geothermal system shift the ca mg hco3 type cold groundwaters to the na hco3 so4 type thermal waters thermal waters are oversaturated at discharge temperatures for aragonite calcite quartz chalcedony magnesite and dolomite minerals giving rise to a carbonate rich scale gypsum and anhydrite minerals are undersaturated with all of the thermal waters boiling during ascent of the thermal fluids produces steam and liquid waters resulting in an increase of the concentrations of the constituents in discharge waters steam fraction y of the thermal waters of which temperatures are above 100 c is between 0 075 and 0 119 reservoir ph is much lower than ph measured in the liquid phase separated at atmospheric conditions since the latter experienced heavy loss of acid gases mainly co2 assessment of the various empirical chemical geothermometers and geochemical modelling suggest that reservoir temperatures vary between 175 c and 200 c

tectonic evolution of the jurassic cretaceous great valley forearc california implications for the franciscan thrust wedge hypothesis interpretation of seismic reflection data and restoration of depositional geometries of cretaceous forearc basin strata in the northwest great valley of california provide important controls on structural reconstructions of the western margin of the sacramento valley and northern coast ranges monoclinal eastward dips of great valley group strata and fault systems striking northwest southeast which are features proposed as evidence for a west dipping blind great valley franciscan sole thrust and related backthrusts instead are expressions of bedding geometry that resulted from folding of the paskenta and related synsedimentary normal faults depositional onlap and a major structural stratigraphic discontinuity the discontinuity separates east dipping aptian and younger great valley group strata from beds of lower great valley group and coast range ophiolite that were deformed and erosionally or structurally truncated by mid cretaceous time dip divergence imaged between the supracrop and subcrop of the discontinuity is not unique to the ancient great valley forearc but is also observed in modern forearc basins advocates of the franciscan thrust wedge model have also proposed that west dipping shingled patterns of seismic events imaged beneath the sacramento valley are imbricate thrust slices of the great valley group this hypothesis however is incompatible with borehole potential field and seismic refraction data that characterize the sacramento valley basement as ophiolitic seaward dipping reflections in the ophiolitic basement of the sacramento valley are analogous to layering developed in the oceanic crust of volcanic rifted margins or generated along midocean ridges thus late stage tectonic mechanisms are not required to interpret a forearc that owes much of its present day bedding architecture to processes coeval with deposition thickening of the great valley group stratigraphic section valanginian turonian in the hanging walls of the paskenta elder creek and cold fork fault zones combined with attenuation or complete omission of preextensional units including the coast range ophiolite and geometric evidence based on seismic reconstructions suggest that these faults are jurassic cretaceous normal faults that developed in a submarine setting down structure views of the great valley outcrop belt simplify otherwise complex map relations and portray the paskenta and related faults as half graben bounding faults that accommodated significant northwestward tectonic transport of hanging wall rocks it is significant that these faults sole into the coast range fault an enigmatic forearc structure that juxtaposes rocks of the franciscan complex blueschists with rocks of the coast range ophiolite and great valley group that have sustained only zeolite grade metamorphism discovery of jurassic cretaceous crustal scale extension in the great valley forearc suggests that a significant part of coast range fault related attenuation developed early in the history of the subduction complex

gas geochemistry and seismotectonics a review abstract publications on soil and spring gases have been examined regarding their relationships with both tectonic and seismic activities the main sources behaviours and uses of species detected in soils and springs are displayed and their mode of sampling and analysing briefly described the main patterns of degassing in soils are described and we outline the wide range of geochemical signatures as the result of both permeability and mineralogical contrasts because thermomineral waters have been in contact with great volumes of crustal rocks at various depths spring gases might be more representative of the local environment than soil gases moreover gas signature comparisons show that spring gases are much more enriched with deep gases and slightly contaminated by atmospheric gases therefore they can be considered as better samples for identifying precursors of earthquakes environmental perturbations are examined and it is shown from divergent cases that pressure temperature soil moisture or earth tides may generate very high perturbations of the degassing process such effects demonstrate that no systematic correction law can be proposed and that removing external contributions from gas concentrations must be performed case by case this demonstrates therefore the need for the simultaneous measurement of external parameters during gas monitoring a qualitative examination of about 150 claimed precursors proposed in the literature has been reviewed as noted by previous authors anomalies appear at distances sometimes much greater than typical source dimensions and occur in the field of strain higher than 10 9 most of them being in the field of strain higher than 10 8 taking into account the very high heterogeneity of such a set of data we can suggest that amplitudes of gas anomalies are independent of both magnitudes and epicentral distances of related earthquakes suggesting local conditions to control amplitudes on the contrary precursory time and duration of anomalies seem to increase both with magnitudes and epicentral distances abundant evidence demonstrates the major role of crustal fluids in the earthquake cycle many works have outlined the fact that crustal instabilities can appear as the result of low stress strain perturbations during loading it has been suggested that motion of fluids may occur at various scales from microcrack fluid transfer up to changes of hydraulic levels of water tables the study of subsequent anomalies is expected to supply a tool for earthquake prediction following previous authors we outline the need for further methodological improvements including the setting up of multiparameter station networks and the simultaneous recording of the main external parameters atmospheric pressure water and air temperature soil moisture for signal processing

spatial structure and landscape associations of srtm error abstract this paper evaluates the spatial structure of shuttle radar topography mission srtm error and its associations with globally available topographic and land cover variables across a wide range of landscapes two continental scale srtm elevation data samples were extracted along with collocated national elevation dataset ned elevations modis composite forest cover percentage and global ecoregion major habitat type codes the larger punctual sample contained nearly 247 000 sites on a regular grid across the conterminous united states while the smaller areal sample consisted of 37 500 45 45 rectangular regions on a regular grid sub pixel positional mismatch was accounted for by finding and using the best local fit between the 1 arc sec horizontal resolution ned product and the 3 arc sec 3 horizontal resolution srtm product slope and aspect were calculated for all samples using the larger point sample we identified associations between srtm error defined as ned srtm 3 differences with these land cover and terrain derivative variables using the areal sample we developed semivariograms of elevation error for tens of thousands of small regions across the united states as well as for sets of these regions with common slope and landcover properties this facilitated a more comprehensive evaluation of the spatial structure of srtm error than has previously been done the punctual sample rmse was 8 6 m conforming to previous estimates of srtm error but many errors in excess of 50 m were identified nearly 90 of these large errors were positive and correlated with high forest cover percentage overall srtm elevations consistently overestimated the surface forest cover and slope were positively correlated with positive bias a strong association of aspect with srtm error was noted with positive error magnitudes peaking for aspects oriented to the northwest and negative error magnitudes peaking for slopes facing southeast error bias standard deviation and semivariograms differed substantially across ecoregion types these variables were incorporated in a regression model to predict srtm error this model explained nearly 60 of the total error variation and has the potential to substantially improve the srtm data product worldwide using globally available datasets

object based classification of global undersea topography and geomorphological features from the srtm30_plus data the analysis of undersea topography and geomorphological features provides necessary information to related disciplines and many applications the development of an automated knowledge based classification approach of undersea topography and geomorphological features is challenging due to their multi scale nature the aim of the study is to develop and evaluate an automated knowledge based obia approach to i decompose the global undersea topography to multi scale regions of distinct morphometric properties and ii assign the derived regions to characteristic geomorphological features first the global undersea topography was decomposed through the srtm30 plus bathymetry data to the so called morphometric objects of discrete morphometric properties and spatial scales defined by data driven methods local variance graphs and nested means and multi scale analysis the derived morphometric objects were combined with additional relative topographic position information computed with a self adaptive pattern recognition method geomorphons and auxiliary data and were assigned to characteristic undersea geomorphological feature classes through a knowledge base developed from standard definitions the decomposition of the srtm30 plus data to morphometric objects was considered successful for the requirements of maximizing intra object and inter object heterogeneity based on the near zero values of the moran s i and the low values of the weighted variance index the knowledge based classification approach was tested for its transferability in six case studies of various tectonic settings and achieved the efficient extraction of 11 undersea geomorphological feature classes the classification results for the six case studies were compared with the digital global seafloor geomorphic features map gsfm the 11 undersea feature classes and their producer s accuracies in respect to the gsfm relevant areas were basin 95 continental shelf 94 9 trough 88 4 plateau 78 9 continental slope 76 4 trench 71 2 abyssal hill 62 9 abyssal plain 62 4 ridge 49 8 seamount 48 8 and continental rise 25 4 the knowledge based obia classification approach was considered transferable since the percentages of spatial and thematic agreement between the most of the classified undersea feature classes and the gsfm exhibited low deviations across the six case studies

anomalous soil co2 degassing in relation to faults and eruptive fissures on mount etna sicily italy the relationships between soil gas emissions and both tectonic and volcano tectonic structures on mt etna have been studied the investigation consisted of soil co2 flux measurements along traverses orthogonal to the main faults and eruptive fissures of the volcano anomalous levels of soil degassing were found mainly in coincidence with faults whereas only 49 of the eruptive fissures were found to produce elevated co2 soil fluxes this result suggests that only zones of strain are able to channel deep gases to the surface according to this hypothesis several previously unknown structures are suggested based on our geochemical data new structural maps of different areas of etna are proposed the soil co2 fluxes observed in this study are higher than those measured in a 1987 study and they are consistent with the higher level of volcanic unrest during the current study

evaluating fuzzy operators of an object based image analysis for detecting landslides and their changes abstract this article presents a method of object based image analysis obia for landslide delineation and landslide related change detection from multi temporal satellite images it uses both spatial and spectral information on landslides through spectral analysis shape analysis textural measurements using a gray level co occurrence matrix glcm and fuzzy logic membership functionality following an initial segmentation step particular combinations of various information layers were investigated to generate objects this was achieved by applying multi resolution segmentation to irs 1d spot 5 and alos satellite imagery in sequential steps of feature selection and object classification and using slope and flow direction derivatives from a digital elevation model together with topographically oriented gray level co occurrence matrices fuzzy membership values were calculated for 11 different membership functions using 20 landslide objects from a landslide training data six fuzzy operators were used for the final classification and the accuracies of the resulting landslide maps were compared a fuzzy synthetic evaluation fse approach was adapted for validation of the results and for an accuracy assessment using the landslide inventory database the fse approach revealed that the and operator performed best with an accuracy of 93 87 for 2005 and 94 74 for 2011 closely followed by the mean arithmetic operator while the or and and operators yielded relatively low accuracies an object based change detection was then applied to monitor landslide related changes that occurred in northern iran between 2005 and 2011 knowledge rules to detect possible landslide related changes were developed by evaluating all possible landslide related objects for both time steps

semi automatic classification of glaciovolcanic landforms an object based mapping approach based on geomorphometry abstract a new object oriented approach is developed to classify glaciovolcanic landforms procedure a and their landform elements boundaries procedure b it utilizes the principle that glaciovolcanic edifices are geomorphometrically distinct from lava shields and plains pedersen and grosse 2014 and the approach is tested on data from reykjanes peninsula iceland the outlined procedures utilize slope and profile curvature attribute maps 20 m pixel and the classified results are evaluated quantitatively through error matrix maps procedure a and visual inspection procedure b in procedure a the highest obtained accuracy is 94 1 but even simple mapping procedures provide good results 90 accuracy successful classification of glaciovolcanic landform element boundaries procedure b is also achieved and this technique has the potential to delineate the transition from intraglacial to subaerial volcanic activity in orthographic view this object oriented approach based on geomorphometry overcomes issues with vegetation cover which has been typically problematic for classification schemes utilizing spectral data furthermore it handles complex edifice outlines well and is easily incorporated into a gis environment where results can be edited or fused with other mapping results the approach outlined here is designed to map glaciovolcanic edifices within the icelandic neovolcanic zone but may also be applied to similar subaerial or submarine volcanic settings where steep volcanic edifices are surrounded by flat plains

unmetamorphosed sedimentary melange with high pressure metamorphic blocks in a nascent forearc basin setting abstract melanges crop out within unmetamorphosed basal great valley group gvg forearc basin strata and between gvg and the underlying coast range ophiolite cro in the san francisco bay region of coastal california these melanges include high pressure hp metamorphic blocks of the franciscan subduction complex that structurally underlies the unmetamorphosed cro as well as blocks of gvg and cro the matrix consists of foliated shale and serpentinite locally interleaved at centimeter scale the melanges strike and dip parallel to bounding gvg sandstones and conglomerates the matrix locally consists of sedimentary breccia and conglomerate made up of clasts of serpentinite and shale gvg sandstones within and bounding the melanges have detrital serpentinite clasts the field relationships indicate a sedimentary origin of the melanges as olistostromal deposits within latest jurassic to earliest cretaceous basal gvg the melanges correlate to units along the eastern margin of the northern coast ranges about 250 km to the north with restoration of post subduction dextral faulting and differ from the latter in the higher proportion of shale stronger matrix foliation and common occurrence of hp blocks similar units may have mistakenly been assigned to the franciscan owing to the foliated nature of the matrix and occurrence of hp blocks this and the broad distribution of localities indicate that these deposits are more widespread than previously believed exhumation rates of coarse grained hp melange blocks may have been 2 to 10 mm yr or higher based on the ages of similar blocks in the coast ranges burial depth of the blocks and depositional age of the enclosing strata exhumation and deposition of franciscan blocks in these gvg melanges predates preserved accretion of similar materials in the adjacent franciscan by at least 30 m y suggesting subduction erosion of previously accreted material or exhumation of the blocks in forearc serpentinite shale diapirs

parameter free delineation of slope units and terrain subdivision of italy abstract quantitative geomorphological and environmental analysis requires the adoption of well defined spatial domains as basic mapping units they provide local boundaries to aggregate environmental and morphometric variables and to perform calculations thus they identify the spatial scale of the analysis grid cells typically aligned with a digital elevation model are the standard mapping unit choice a wiser choice is represented by slope units irregular terrain partitions delimited by drainage and divide lines that maximise geomorphological homogeneity within each unit and geomorphological heterogeneity between neighbouring units adoption of slope units has the advantage of enforcing a strong relation with the underlying topography absent in grid cell based analyses but their objective delineation is still a challenge a given study area admits different slope unit maps differing in number and size of units here we devise an objective optimisation procedure for slope units suitable for study areas of arbitrarily large size and with varying terrain heterogeneity we applied the new approach to the whole of italy resulting in a map containing about 330 000 slope unit polygons of different sizes and shapes the method is parameter free due to objective optimisation using a morphometric segmentation function and the map is readily available for general purpose studies a cluster analysis of slope units properties compared with terrain elevation slope drainage density and lithology confirmed that the terrain partition is geomorphologically sound we suggest the use of the slope unit map for different terrain zonations including landslide susceptibility modelling hydrological and erosion modelling geo environmental ecological forestry agriculture and land use land cover studies requiring the identification of homogeneous terrain domains facing distinct directions

a model for ischia hydrothermal system evidences from the chemistry of thermal groundwaters abstract ischia volcano in central italy has long been known for its copious surface hydrothermal manifestations signs of a pervasive circulation of hot fluids in the subsurface because of the significant chemical heterogeneity of fumarolic gas discharges and hot spring discharges evidences of a complex hydrothermal setting a definite model of fluid circulation at depth is currently unavailable in spite of the several previous efforts here we report on the chemical and isotopic composition of 120 groundwater samples collected during several sampling surveys from 2002 to 2007 the acquired data suggest that the composition of surface manifestations reflect contributions from meteoric water sea water and thermal fluids rising from two distinct hydrothermal reservoir with equilibrium temperatures of respectively 150 c and 270 c and depths of 150 300 m and 300 m but possibly 1000 m we also make use of an isotopic characterization of the dissolved gas phase in thermal waters to demonstrate that the ischia hydrothermal system is currently supplied by a deep rising gas component dgc characterized by co2 97 7 1 2 vol on a water free basis 13cco2 3 51 0 9 and helium isotopic ratio of about 3 5 ra 3he 4he ratio normalized to the air ratio ra likely magmatic in origin an assessment of the thermal budget for ischia hydrothermal system is also presented in the attempt to derive a first estimate of the size and rate of degassing of the magmatic reservoir feeding the gas emissions we calculate that a heat flow of about 153 222 mw presently drives hydrothermal circulation on the island which we suggest is supplied in convective form e g by the ascent of a high t magmatic vapour phase by complete degassing of 2 2 3 3 107 m3 yr 1 of trachytic magma with 2 1 wt dissolved h2o content if extrapolated to entire period of quiescence lasting since the arso eruption in 1302 a d this volume corresponds to 1 6 2 3 1010 m3 of magma degassed in about 700 years of quiescent activity

isotopic and chemical composition of water and steam discharges from volcanic magmatic hydrothermal systems of the guanacaste geothermal province costa rica the guanacaste geothermal province encompasses three major geothermal systems each centered on its respective volcanic structure rincon de la vieja to the nw miravalles in the center and tenorioto the se each shows corresponding sets of surface manifestations vapor discharges from fumaroles and steam heated pools at altitudes 500 m lower temperature so4cl springs on the lower slopes of the respective volcano and cooler neutral cl springs to the s of the volcanic chain at altitudes 500 m the production of hco3 rich waters is limited to a narrow belt stretching to the s of miravalles volcano chemical and isotopic evidence suggests that the neutral cl waters also discharged from deep wells are derived from a more primitive clso4 water formed by transfer of readily mobilised originally magmatic constituents to deeply circulating groundwater isotopic evidence suggests that this groundwater is derived largely from areas to the north of the volcanic chain the presence of immature waters within drillable depth is indicated by the incursion of an acid so4 water into a well at miravalles after deepening to 2000 m as the cl waters rise they start to boil the separated vapors feed the fumaroles and steam heated features at the surface the residual water travels underground to be discharged some 5 25 km to the s the uniformity in chemical and isotopic compositions of the neutral cl waters is compatible with the assumption that the individual thermal systems are linked at depth to form large contiguous geothermal reservoirs beneath the guanacaste geothermal province

global mercury flux from volcanic and geothermal sources abstract the global hg flux from natural sources is poorly known we present data on hg levels in volcanic fumaroles that in combination with sulfur analyses and published so 2 flux data lead to new global hg flux estimates the volcanogenic hg flux from passively degassing volcanoes is small 30 mg hg yr the flux from erupting volcanoes is much larger but less well constrained we estimate it at about 800 mg yr these data are interpreted as evidence for early hg degassing from magmas geothermal sources contribute roughly 60 mg yr hg to the atmosphere an estimate based on average hg contents of hot springs and global convective heat transport total natural hg emissions from land amount to 1290 mg yr including a revised soil vapor flux of 400 mg yr estimates of anthropogenic contributions to the atmospheric hg budget vary between 3000 and 11 500 mg yr and are substantial compared to our natural hg flux estimate

assessment of multiresolution segmentation for delimiting drumlins in digital elevation models mapping or delimiting landforms is one of geomorphology s primary tools computer based techniques such as land surface segmentation allow the emulation of the process of manual landform delineation land surface segmentation exhaustively subdivides a digital elevation model dem into morphometrically homogeneous irregularly shaped regions called terrain segments terrain segments can be created from various land surface parameters lsp at multiple scales and may therefore potentially correspond to the spatial extents of landforms such as drumlins however this depends on the segmentation algorithm the parameterization and the lsps in the present study we assess the widely used multiresolution segmentation mrs algorithm for its potential in providing terrain segments which delimit drumlins supervised testing was based on five 5 m dems that represented a set of 173 synthetic drumlins at random but representative positions in the same landscape five lsps were tested and four variants were computed for each lsp to assess the impact of median filtering of dems and logarithmic transformation of lsps the testing scheme 1 employs mrs to partition each lsp exhaustively into 200 coarser scales of terrain segments by increasing the scale parameter sp 2 identifies the spatially best matching terrain segment for each reference drumlin and 3 computes four segmentation accuracy metrics for quantifying the overall spatial match between drumlin segments and reference drumlins results of 100 tests showed that mrs tends to perform best on lsps that are regionally derived from filtered dems and then log transformed mrs delineated 97 of the detected drumlins at sp values between 1 and 50 drumlin delimitation rates with values up to 50 are in line with the success of manual interpretations synthetic dems are well suited for assessing landform quantification methods such as mrs since subjectivity in the reference data is avoided which increases the reliability validity and applicability of results

object representations at multiple scales from digital elevation models in the last decade landform classification and mapping has developed as one of the most active areas of geomorphometry however translation from continuous models of elevation and its derivatives slope aspect and curvatures to landform divisions landforms and landform elements is filtered by two important concepts scale and object ontology although acknowledged as being important these two issues have received surprisingly little attention this contribution provides an overview and prospects of object representation from dems as a function of scale relationships between object delineation and classification or regionalization are explored in the context of differences between general and specific geomorphometry a review of scales issues in geomorphometry ranging from scale effects to scale optimization techniques is followed by an analysis of pros and cons of using cells and objects in dem analysis prospects for coupling multi scale analysis and object delineation are then discussed within this context we propose discrete geomorphometry as a possible approach between general and specific geomorphometry discrete geomorphometry would apply to and describe land surface divisions defined solely by the criteria of homogeneity in respect to a given land surface parameter or a combination of several parameters homogeneity in its turn should always be relative to scale

expert driven semi automated geomorphological mapping for a mountainous area using a laser dtm in this paper a semi automated method is presented to recognize and spatially delineate geomorphological units in mountainous forested ecosystems using statistical information extracted from a 1 m resolution laser digital elevation dataset the method was applied to a mountainous area in austria first slope angle and elevation characteristics were determined for each key geomorphological unit occurring in the study area second a map of slope classes derived from the laser dtm was used in an expert driven multilevel object oriented approach the resulting classes represent units corresponding to landforms and processes commonly recognized in mountain areas fluvial terrace alluvial fan slope with mass movement talus slope rock cliff glacial landform shallow incised channel and deep incised channel the classification result was compared with a validation dataset of geomorphological units derived from an analogue geomorphological map for the above mentioned classes the percentages of correctly classified grid cells are 69 79 50 64 32 61 23 and 70 respectively the lower values of 32 and 23 are mainly related to inaccurate mapping of rock cliffs and shallow incised channels in the analogue geomorphological map the accuracy increased to 76 and 54 respectively if a buffer is applied to these specific units it is concluded that high resolution topographical data derived from laser dtms are useful for the extraction of geomorphological units in mountain areas

soil gas co 2 ch 4 and h 2 distribution in and around las canadas caldera tenerife canary islands spain abstract diffuse degassing of co 2 ch 4 and h 2 was investigated at the surface environment of canadas caldera canary islands during the gas survey carried out in the summer of 1995 soil co 2 concentration varied significantly from atmospheric levels to 30 while soil ch 4 and h 2 contents ranged from 5 to 851 ppm and from 0 5 to 620 ppm respectively soil co 2 ch 4 and h 2 distribution suggests that high diffuse degassing at canadas caldera is volcanic structurally controlled anomalous soil h 2 concentrations were identified at the summit of teide and outside caldera boundaries where the most recent eruption of tenerife island occurred 13 c co 2 data showed a magmatic mixed magmatic biogenic and biogenic origin while a biogenic origin is suggested for soil ch 4 at canadas caldera and its surroundings by coupling the co 2 3 he ratio with the 3 he 4 he ratio of fumarolic gas samples from the summit of teide we propose three possible sources for carbon morb type organic carbon and carbonate

automated classification of landform elements using object based image analysis this paper presents an automated classification system of landform elements based on object oriented image analysis first several data layers are produced from digital terrain models dtm elevation profile curvature plan curvature and slope gradient second relatively homogenous objects are delineated at several levels through image segmentation these object primatives are classified as landform elements using a relative classification model built both on the surface shape and on the altitudinal position of objects so far slope aspect was not used in classification the classification has nine classes peaks and toe slopes defined by the altitudinal position or the degree of dominance steep slopes and flat gentle slopes defined by slope gradients shoulders and negative contacts defined by profile curvatures head slopes side slopes and nose slopes defined by plan curvatures classes are defined using flexible fuzzy membership functions results are visually analyzed by draping them over dtms specific fuzzy classification options were used to obtain an assessment of output accuracy two implementations of the methodology are compared using 1 romanian datasets and 2 berchtesgaden national park germany the methodology has proven to be reproducible readily adaptable for diverse landscapes and datasets and useful in respect to providing additional information for geomorphological and landscape studies a major advantage of this new methodology is its transferability given that it uses only relative values and relative positions to neighboring objects the methodology introduced in this paper can be used for almost any application where relationships between topographic features and other components of landscapes are to be assessed

high resolution broad scale mapping of soil parent material using object based image analysis obia of lidar elevation data abstract precise mapping of subsurface properties especially soil parent material spm is critical to understanding most geomorphic and hydrologic processes because spatial variability of the subsurface properties is highly correlated to the morphology of the earth s surface dems and aerial satellite imagery have been used successfully for lithological mapping however most of the studies using this approach have used either coarse resolution dems or covered limited areas lidar derived topographic attributes may provide an opportunity for finer resolution mapping of subsurface properties at much larger spatial scales here we present an approach that uses object based image analysis obia the process of clustering pixels into homogeneous objects paired with a classification tree ct algorithm to map spm at 1 m resolution and at a regional spatial scale using lidar derived topographic attributes combining obia of topographic attributes with the ct method proved to be an efficient approach for mapping of spm at fine resolution and broad scales using field acquired spm samples we found that this approach was able to explain 73 5 of the variance of three spm classes i e bedrock glacial till sands using only four common topographic metrics i e slope topographic wetness index terrain ruggedness index multi resolution topographic positioning index when comparing our approach to other classification methods and to other studies that have mapped spm we obtain the highest overall accuracy with a value of 85 this approach allowed us to produce a fine resolution 185 km2 spm map in a heterogeneous post glaciation precambrian shield setting

regional and local topography subdivision and landform mapping using srtm derived data a case study in southeastern brazil topographic subdivisions and landforms are important relief characteristics that serve as a basis for several types of regional and local planning this paper presents an assessment of the application of a global landform classification method on a regional scale using sao paulo state as the study area and on a local scale using the city of sao paulo as the study area in addition a new approach that includes elevation derivatives for local analysis is presented the study hypothesizes that the automated object based classification of topography from shuttle radar topography mission srtm data method could also be used for local mapping when supported by elevation derivative data srtm data were used in the regional approach and post processed elevation data derived from srtm were used for the local analysis the results were compared with the best available geomorphological maps and topographic surface descriptions of the region the new method resulted in a regional scale product in which the boundaries and features of the topography matched those in the geomorphological maps and in the literature the method did not perform well when classifying the local topographic subdivisions of sao paulo even when using the interpolated elevation data however the surface edges and shapes identified in the topographic maps were represented in the resulting map to refine the results a new approach was proposed using data derived from a digital elevation model such as drainage densities horizontal and vertical curvatures and slope gradients the use of these products in the image segmentation process and classification criteria was fundamental for obtaining the results theoretical thresholds were used to define the relief classes and landform characteristics were taken into account in developing the landform map the success of this new approach is attributed to the comprehensive database that supported the topographic subdivision analysis in summary this study indicates that a method developed for use on a global scale can be replicated for use on a regional scale but not on a local scale the new approach produced reasonable results and can be used in other regions greater detail can be obtained using various thresholds of horizontal and vertical curvatures for example when delineating hazard areas the products have potential applications in urban planning ecological economic zoning urban drainage hazard mitigation environmental issues erosional dynamics and transportation planning

early cretaceous transition from nonaccretionary behavior to strongly accretionary behavior within the franciscan subduction complex 1 during subduction at the franciscan trench beginning at 170 160 ma and continuing to the present marine sedimentary and lesser volcanic rocks have been underthrust accreted and metamorphosed to form the franciscan accretionary wedge the south fork mountain schist sfms forms the eastern margin and structural top of the wedge and so was apparently the first unit of substantial size to accrete into the franciscan new u pb ages of detrital zircons and 40ar 39ar ages of metamorphic white micas indicate that the sfms accreted surprisingly late in the time span of franciscan subduction probably at ca 123 ma at least parts of the valentine spring formation and yolla bolly terrane accreted soon thereafter therefore accretion of the sfms apparently marks a fundamental transition from virtually nonaccretionary behavior to strongly accretionary behavior in the franciscan forearc about 75 of modern forearcs are nonaccretionary so recognition of an early nonaccretionary period is consistent with modern examples the franciscan mafic high grade exotic blocks and related very small slabs which yield ca 132 to 169 ma metamorphic ages are the only well documented rock record of the early 40 m y long nonaccretionary period and represent very sparse accretion during that interval the transition into an accretionary regime at ca 123 ma was essentially synchronous with the end of the late jurassic early cretaceous magmatic lull in the sierra nevada magmatic arc with the waning of early cretaceous faulting and warping within the great valley forearc basin and possibly with changes in motion vectors of the pacific and farallon plates

alteration of the oceanic crust implications for geochemical cycles of lithium and boron abstract fresh tholeiitic basalt glass has been reacted with seawater at 150 c water rock mass ratio of 10 and fresh diabase has been reacted with a na k ca cl fluid at 375 c water rock mass ratios of 1 2 and 5 to understand better the role of temperature basalt composition and water rock mass ratio on the direction and magnitude of b and li exchange during basalt alteration at 150 c slight but nevertheless significant amounts of b and li were removed from seawater and incorporated into a dominantly smectite alteration phase at 375 c however b and li were leached from basalt b behaved as a soluble element and attained concentrations in solution limited only by the b concentration in basalt and the water rock mass ratio li however was less mobile for example at water rock mass ratios of 1 2 and 5 the percent of li leached from basalt was 58 70 and 92 respectively this suggests some mineralogic control on li mobility during hydrothermal alteration of basalt especially at low water rock mass ratios in general these results as well as those for b are consistent with the temperature dependent chemistry of altered seafloor basalt and the chemistry of ridge crest hydrothermal fluids based on the distribution and chemistry of products of seafloor weathering low 150 c and high temperature hydrothermal alteration of basalt and the chemistry of ridge crest hydrothermal fluids it was estimated that alteration of the oceanic crust is a li source for seawater this is not true for b however since the hot spring flux estimated for b is balanced by low temperature basalt alteration these data coupled with b and li flux estimates for other processes e g continental weathering clay mineral adsorption authigenic silicate formation and formation of siliceous skeletal material yield new insight into the b and li geochemical cycles calculations performed here indicate relatively good agreement between the magnitude of b and li sources and sinks the geochemical cycle of b however may be affected by serpentinization of mantle derived peridotite in oceanic fracture zones serpentinites are conspicuously enriched in b and if the b source for these rocks is seawater then an additional b sink exists which must be integrated into the b geochemical cycle however until more data are available in terms of areal extent of serpentinization serpentite chemistry and isotopic composition the importance of b in these rocks with respect to the b geochemical cycle remains speculative at best

using textural analysis for regional landform and landscape mapping eastern guiana shield availability of digital elevation models dem of increased spatial resolution has triggered interest in texture based methods for automated geomorphometry this prospect is all the more appealing concerning tropical countries for which mapping of geomorphic entities has remained limited despite its relevance for natural resource assessment and land planning in this paper we applied to the shuttle radar topography mission srtm dem a multiscale texture analysis based on fourier 2d periodogram foto method to reach a spatially coherent mapping that would agree with current knowledge over the conterminous territories of french guiana and amapa brazil through a principal component analysis foto extracted textural features were found complementary and combined with six common physiographic criteria convexity wetness index dissection elevation and percent of steep and low slopes calculated from the dem this provided a primary semiautomated mapping of 16 classes of landform types to increase legibility we aggregated into eight landscape unit classes that were the most similar in terms of texture and relief criteria while being frequently contiguous the resulting map was compared with existing maps that were however more local or of lesser resolution and informative content over the region of interest multiscale fourier spectra proved useful to depict land surface texture and in synergy with relief variables allowed identifying a large variety of landforms for broad scale geomorphic mapping in the humid tropics

landslides in eastern honshu induced by the 2011 tohoku earthquake in this article we discuss the character and spatial pattern of coseismic landslides from the eastern honshu region of japan which was strongly shaken in the 2011 tohoku earthquake we developed a detailed geospatial database of 3477 landslides based on postearthquake field surveys and examination of high resolution satellite imagery across a 28 380 km2 landslide study area analysis of the database shows that a substantial majority 80 of landslides occurred in quaternary soil and neogene rock units despite their abundance in the study area relatively few landslides occurred in pre neogene rocks i e older than 23 ma further examination of the data showed that the most common types of landslides were 1 disrupted landslides in neogene sedimentary rocks and 2 lateral spreading in quaternary sediments however we found that coseismic landslide erosion i e debris mobilization was almost fully dominated by lateral spreading within quaternary sediments when comparing the landslide inventory with ground motions recorded by dense regional seismic arrays we found no statistically significant correlation between landslide intensity and ground motion within the study area online material derivation of empirical parameters used in the area to volume transformations for lateral spreads

combining geomorphometry feature extraction techniques and earth surface processes research the way forward abstract in recent years the wealth of technological development revolutionised our ability to collect data in geosciences due to the unprecedented level of detail of these datasets geomorphologists are facing new challenges giving more in depth answers to a broad er range of fundamental questions across the full spectrum of the earth s and planetary processes this contribution builds on the existing literature of geomorphometry the science of quantitative land surface analysis and feature extraction translate land surface parameters into extents of geomorphological elements it provides evidence of critical themes as well as emerging fields of future research in the digital realm supporting the likely effectiveness of geomorphometry and feature extractions as they are advancing the theoretical empirical and applied dimension of geomorphology the review further discusses the role of geomorphometric legacies and scientific reproducibility and how they can be implemented in the hope that this will facilitate action towards improving the transparency and efficiency of scientific research and accelerate discoveries in geomorphology in the current landscape substantial changes in landforms ecosystems land use hydrological routing and direct anthropogenic modifications impact systems across the full spectrum of geomorphological processes although uncertainties in the precise nature and likelihood of changes exist geomorphometry and feature extraction can aid exploring process regimes and landscape responses taken together they can revolutionise geomorphology by opening the doors to improved investigations crossing space and time scales blurring the boundaries between traditional approaches and computer modelling and facilitating cross disciplinary research ultimately the exploitation of the available wealth of digital information can help to translate our understanding of geomorphic processes which is often based on observations of past or current conditions into the rapidly changing future

evaluating metrics of local topographic position for multiscale geomorphometric analysis abstract the field of geomorphometry has increasingly moved towards the use of multiscale analytical techniques due to the availability of fine resolution digital elevation models dems and the inherent scale dependency of many dem derived attributes such as local topographic position ltp ltp is useful for landform and soils mapping and numerous other environmental applications multiple ltp metrics have been proposed and applied in the literature however elevation percentile ep is notable for its robustness to elevation error and applicability to non gaussian local elevation distributions both of which are common characteristics of dem data sets multiscale ltp analysis involves the estimation of spatial patterns using a range of neighborhood sizes traditionally achieved by applying spatial filtering techniques with varying kernel sizes while ep can be demonstrated to provide accurate estimates of ltp the computationally intensive method of its calculation makes it unsuited to multiscale ltp analysis particularly at large neighborhood sizes or with fine resolution dems this research assessed the suitability of three ltp metrics for multiscale terrain characterization by quantifying their computational efficiency and by comparing their ability to approximate ep spatial patterns under varying topographic conditions the tested ltp metrics included deviation from mean elevation dev percent elevation range per and the novel relative topographic position rtp index the results demonstrated that dev calculated using the integral image technique offers fast and scale invariant computation dev spatial patterns were strongly correlated with ep r2 range of 0 699 to 0 967 under all tested topographic conditions rtp was also a strong predictor of ep r2 range of 0 594 to 0 917 per was the weakest predictor of ep r2 range of 0 031 to 0 801 without offering a substantial improvement in computational efficiency over rtp per was therefore determined to be unsuitable for most multiscale applications it was concluded that the scale invariant property offered by the integral image used by the dev method counters the minor losses in robustness compared to ep making dev the optimal ltp metric for multiscale applications

landscape similarity retrieval and machine mapping of physiographic units abstract we introduce landscape similarity a numerical measure that assesses affinity between two landscapes on the basis of similarity between the patterns of their constituent landform elements such a similarity function provides core technology for a landscape search engine an algorithm that parses the topography of a study area and finds all places with landscapes broadly similar to a landscape template a landscape search can yield answers to a query in real time enabling a highly effective means to explore large topographic datasets in turn a landscape search facilitates auto mapping of physiographic units within a study area the country of poland serves as a test bed for these novel concepts the topography of poland is given by a 30 m resolution dem the geomorphons method is applied to this dem to classify the topography into ten common types of landform elements a local landscape is represented by a square tile cut out of a map of landform elements a histogram of cell pair features is used to succinctly encode the composition and texture of a pattern within a local landscape the affinity between two local landscapes is assessed using the wave hedges similarity function applied to the two corresponding histograms for a landscape search the study area is organized into a lattice of local landscapes during the search the algorithm calculates the similarity between each local landscape and a given query our landscape search for poland is implemented as a geoweb application called terraex pl and is available at http sil uc edu given a sample or a number of samples from a target physiographic unit the landscape search delineates this unit using the principles of supervised machine learning repeating this procedure for all units yields a complete physiographic map the application of this methodology to topographic data of poland results in the delineation of nine physiographic units the resultant map bears a close resemblance to a conventional physiographic map of poland differences can be attributed to geological and paleogeographical input used in drawing the conventional map but not utilized by the mapping algorithm

deep learning based approach for landform classification from integrated data sources of digital elevation model and imagery abstract landform classification is one of the most important aspects in geomorphological research dividing the earth s surface into diverse geomorphological types thus an accurate classification of landforms is a key procedure in describing the topographic characteristics of a given area and understanding their inner geomorphological formation processes however landform types are not always independent of one another due to the complexity and dynamics of interior and external forces furthermore transitional landforms with gradually changing surface morphologies are widely distributed on the earth s surface with this situation classifying these complex and transitional landforms with traditional landform classification methods is hard in this study a deep learning dl algorithm was introduced aiming at automatically classifying complex and transitional landforms this algorithm was trained to learn and extract landform features from integrated data sources these integrated data sources contain different combinations of imagery digital elevation models dems and terrain derivatives the loess plateau in china which contains complex and transitional loess landforms was selected as the study area for data training in addition two sample areas in the loess plateau with complex and transitional loess hill and ridge landforms were used to validate the classified landform types by using the proposed dl method meanwhile a comparative analysis between the proposed dl and random forest rf methods was also conducted to investigate their capabilities in landform classification the proposed dl approach can achieve the highest landform classification accuracy of 87 in the transitional area with data combination of dems and images in addition the proposed dl method can achieve a higher accuracy of landform classification with better defined landform boundaries compared to the rf method the classified loess landforms indicate the different landform development stages in this area finally the proposed dl method can be extended to other landform areas for classifying their complex and transitional landforms

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

fluid geochemistry of hydrothermal systems in the arica parinacota tarapaca and antofagasta regions northern chile we investigate the chemical and isotopic composition of water and gas thermal discharges from six hydrothermal systems in the tarapaca and antofagasta regions northern chile surire puchuldiza tuja pampa lirima pampa apacheta el tatio and torta de tocorpuri to determine the chemical physical conditions at the fluid source the chemical facies of the thermal discharges vary from na cl el tatio puchuldiza tuja and part of surire where so42 rich waters also occur to na ca2 cl so42 pampa lirima ca2 so42 hco3 torta de tocorpuri and ca2 so42 pampa apacheta the gas seeps are characterized by the dominance of co2 h2s and ch4 with n2 ar ratios that occasionally are up to 450 significant amounts of so2 and hcl are present at pampa apacheta water and gas geothermometry suggests that el tatio and puchuldiza tuja fluid reservoirs have relatively high reservoir equilibrium temperature up to 270 c gases from pampa apacheta apparently equilibrated at unusually high temperature for hydrothermal fluids up to 350 c being likely related to an active magmatic system as testified by the presence of highly acidic gas compounds such as so2 and hcl on the contrary low equilibrium temperatures were calculated for the surire fluids 200 c suggesting interactions of deep originated fluids with meteoric water at shallow depth shallow low temperature aquifers mask any signal of deep fluids in the pampa lirima and torta de tocorcupi thermal discharges despite the variations in temperatures he isotopic compositions and redox conditions of the fluid reservoirs consistently indicate a significant contribution from magmatic degassing although geophysical studies are necessary to better constrain the geothermal potential of northern chile the geothermometric estimations carried out in the present study indicate that el tatio pampa apacheta surire and puchuldiza tuja can be regarded as the most promising areas and deserve more detailed geological investigations

geothermal exploration using surface mercury geochemistry abstract shallow soil mercury surveys can be used effectively in exploration for geothermal resources soil mercury data from six areas in nevada california and new mexico are analyzed using contour maps histogram and probability graphs plotting on probability graphs allows background and anomalous populations to be resolved even when considerable overlap between populations is present as is shown in several examples separate soil mercury populations can be plausibly interpreted mercury data can significantly enhance the structural understanding of a prospect and can yield important information about the geothermal resource

an automated approach for extracting barrier island morphology from digital elevation models abstract the response and recovery of a barrier island to extreme storms depends on the elevation of the dune base and crest both of which can vary considerably alongshore and through time quantifying the response to and recovery from storms requires that we can first identify and differentiate the dune s from the beach and back barrier which in turn depends on accurate identification and delineation of the dune toe crest and heel the purpose of this paper is to introduce a multi scale automated approach for extracting beach dune dune toe dune crest and dune heel and barrier island morphology the automated approach introduced here extracts the shoreline and back barrier shoreline based on elevation thresholds and extracts the dune toe dune crest and dune heel based on the average relative relief rr across multiple spatial scales of analysis the multi scale automated rr approach to extracting dune toe dune crest and dune heel based upon relative relief is more objective than traditional approaches because every pixel is analyzed across multiple computational scales and the identification of features is based on the calculated rr values the rr approach out performed contemporary approaches and represents a fast objective means to define important beach and dune features for predicting barrier island response to storms the rr method also does not require that the dune toe crest or heel are spatially continuous which is important because dune morphology is likely naturally variable alongshore