on the size distribution of solution dolines in carbonate karst lognormal or power model abstract dolines or closed karst depressions are the most characteristic feature of karst landscapes the two main types of doline are those formed by the removal of material by solution and those formed by the geological processes of collapse or suffosion solution dolines are most frequently found in carbonate karst in high relief karst massifs various algorithms can be used to identify and delineate dolines in high resolution digital elevation models dem where the lower size limit is determined by the resolution of the dem i e the size of the cell or the dem pixel in terrain units the work presented here addresses the size distribution of dolines which is a significant component of the geomorphometric analysis of dolines on the basis of experimental results various authors have advocated the lognormal or the power distribution as the best fit to experimental data a power distribution is consistent with a fractal structure implying the fractal nature of the sizes of dolines which in turn may reflect a relationship between size and the structural controls of fracture networks and the fractal fragmentation of the terrain this paper presents case studies of four karst landscapes that are representative of karst massifs in spain two of these are located in the pyrenees in the north of spain and two are located in the betic mountains in the south of spain in all four cases a lognormal distribution provides a bad fit while a power law distribution provides a good fit in three cases and in the fourth case provides a good fit for dolines that have a diameter greater than 50 m

analysis of dolines using multiple methods applied to airborne laser scanning data abstract delineating dolines is not a straightforward process especially in densely vegetated areas this paper deals quantitatively with the surface karst morphology of a miocene limestone occurrence in the styrian basin austria the study area is an isolated karst mountain with a smooth morphology former planation surface of pliocene age densely vegetated mixed forest and with a surface area of 1 3 km 2 the study area is located near the city of wildon and is named wildoner buchkogel the aim of this study was to test three different approaches in order to automatically delineate dolines the data basis for this was a high resolution digital terrain model dtm derived from airborne laser scanning als and with a raster resolution of 1 1 m the three different methods for doline boundary delineation are a the traditional method based on the outermost closed contour line b boundary extraction based on a drainage correction algorithm filling up pits and c boundary extraction based on hydrologic modelling watershed extracted features are integrated in a gis environment and analysed statistically regarding spatial distribution shape geometry elongation direction and volume the three methods lead to different doline boundaries and therefore investigated parameters show significant variations the applied methods have been compared with respect to their application purpose depending on delineation process between 118 and 189 dolines could be defined the high density of surface karst features demonstrates that solutional processes are major factors in the landscape development of the wildoner buchkogel furthermore the correlation to the landscape evolution of the grazer bergland is discussed

fractal dimensions of sinkholes abstract sinkhole perimeters are probably fractals d 1 209 1 558 for sinkholes with areas larger than 10 000 m2 based on area perimeter plots of digitized data from karst surfaces developed on six geologic units in the united states the sites in florida kentucky indiana and missouri were studied using maps with a scale of 1 24 000 size number distributions of sinkhole perimeters and areas may also be fractal although data for small sinkholes is needed for verification studies based on small scale maps are needed to evaluate the number and roughness of small sinkhole populations

a fractal based approach to lake size distributions 1 the abundance and size distribution of lakes is critical to assessing the role of lakes in regional and global biogeochemical processes lakes are fractal but do not always conform to the power law size distribution typically associated with fractal geographical features here we evaluate the fractal geometry of lakes with the goal of explaining apparently inconsistent observations of power law and non power law lake size distributions the power law size distribution is a special case for lakes near the mean elevation lakes in flat regions are power law distributed while lakes in mountainous regions deviate from power law distributions empirical analyses of lake size data sets from the adirondack mountains in new york and the flat island of gotland in sweden support this finding our approach provides a unifying framework for lake size distributions indicates that small lakes cannot dominate total lake surface area and underscores the importance of regional hypsometry in influencing lake size distributions

automated delineation of karst sinkholes from lidar derived digital elevation models abstract sinkhole mapping is critical for understanding hydrological processes and mitigating geological hazards in karst landscapes current methods for identifying sinkholes are primarily based on visual interpretation of low resolution topographic maps and aerial photographs with subsequent field verification which is labor intensive and time consuming the increasing availability of high resolution lidar derived digital elevation data allows for an entirely new level of detailed delineation and analyses of small scale geomorphologic features and landscape structures at fine scales in this paper we present a localized contour tree method for automated extraction of sinkholes in karst landscapes one significant advantage of our automated approach for sinkhole extraction is that it may reduce inconsistencies and alleviate repeatability concerns associated with visual interpretation methods in addition the proposed method has contributed to improving the sinkhole inventory in several ways 1 detection of non inventoried sinkholes 2 identification of previously inventoried sinkholes that have been filled 3 delineation of sinkhole boundaries and 4 characterization of sinkhole morphometric properties we applied the method to fillmore county in southeastern minnesota usa and identified three times as many sinkholes as the existing database for the same area the results suggest that previous visual interpretation method might significantly underestimate the number of potential sinkholes in the region our method holds great potential for creating and updating sinkhole inventory databases at a regional scale in a timely manner

fractals in karst the analysis of cave survey data is used to establish that cave length exhibits fractal self similar behaviour with dimensions in the range 1 1 5 over a range of measurement resolutions from 1 to 100 m it is suggested that fractal dimensions together with their range of applicability will prove to be useful parameters for the study of caves

tectonothermal chronology of early cadomian arc development in guernsey and sark channel islands the cadomian orogen exposed in nw france and the channel islands comprises a collage of variably displaced terranes which record the late proterozoic evolution of a continental margin within a complex subduction zone on the islands of guernsey and sark calc alkaline quartz diorite stocks were emplaced during early stages of the cadomian orogeny zircons from two stocks of deformed quartz diorite display evidence of inheritance in larger and more magnetic fractions upper intercept ages for these discordant concentrates are c 1300 ma sm nd whole rock model ages t dm suggest older ages of c 2000 ma conversely the smallest and least magnetic zircons exhibit a distinct lead loss pattern suggesting that the 207 pb 206 pb dates of c 700 ma correspond to the time of crystallization of the stocks and provide a lower age constraint for initiation of subduction related magmatism in the cadomian orogen hornblende concentrates from deformed quartz diorite stocks exposed on guernsey and sark display discordant 40 ar 39 ar age spectra five samples record well defined isotope correlation ages ranging between 596 ma and 606 ma a hornblende concentrate from host orthogneiss sark yields a plateau age of 608 ma the hornblende ages are interpreted as dating post metamorphic cooling following late proterozoic deformation and metamorphism within the arc system both magmatic and cooling ages from this early cadomian arc contrast with those of younger initial tectonothermal activity c 570 ma and c 540 ma in other cadomian terrane elements and suggest palinspastic separation until very late stages of the orogeny the polyphase nature of this late proterozoic activity is similar to that of related orogens which probably occupied similar tectonic settings along the margin of gondwana e g sw iberia west africa

c slip in quartz from subsolidus deformed granite abstract the slip behaviour of quartz from a granite and granitic veins during subsolidus high temperature conditions 700 800 c of deformation is studied by lattice preferred orientation lpo and microstructural techniques lpos with a point maximum of c axes parallel to the shear direction which is close to the stretching lineation are presented and interpreted with the aid of light and electron microscopy in terms of c as the dominant slip direction during plastic deformation microscopy of such samples reveals the presence of 0001 tilt boundaries and free 0001 burgers vector dislocations in edge orientations a change in lpo in a decreasing temperature environment from c axes parallel to the shear direction to c axes normal to the shear direction documents a fabric transition from the rare c slip to the more common a slip fabric it is concluded that conditions of high temperature and partial pressure of water are required to initiate dominant c slip during deformation at geological strain rates

an integrated framework to identify and analyze karst sinkholes abstract sinkholes are the most typical surface feature of karst landscapes their correct mapping is of great importance for a proper assessment of the possible occurrence of new events and the likely effects they could have on the anthropogenic environment in this work we compare and discuss different ways to map sinkholes including heuristic approach automatic mapping through different resolution dtms and digital aerial photo interpretation aimed at highlighting advantages and drawbacks of the multiple approaches for our purpose we use a study area in the murge of apulia se italy where many sinkholes of several typologies are present to characterize the landscape to evaluate the reliability of the sinkhole mapping we set up a conceptual methodology that integrates a semi automatic method with the heuristic approach with a special focus on the importance of incorporating digital stereoscopic interpretation in detail we used as input two dtms at different resolution aimed to test the robustness of the automatic method in different circumstances comparison of the data produced by the different approaches illustrated how the number density and boundaries of the sinkholes may vary as a function of the input data the automated mapping provides reliable results in terms of number dimensions and morphometric attributes of sinkholes and appears to be particularly useful when large areas must be analyzed within the whole process we stress the role of the expert geomorphologist who must determine the accuracy of the product obtained with the automated mapping by correcting eliminating features not attributable to karst processes the presented approach highlights the potential of digital stereoscopy in substantially decreasing the errors encountered with traditional analog mapping simultaneously reducing the working time significantly

the transition from magmatic to high temperature solid state deformation implications from the mount stuart batholith washington criteria for syntectonic emplacement of plutons are commonly ambiguous the strongest single criterion is probably the preservation of a continuous transition from submagmatic to high temperature solidstate deformation this transition is not commonly documented an exception is the mount stuart batholith which displays a variety of syntectonic structures within its sheared northeastern margin including the following 1 s c fabrics that range from submagmatic to high temperature solid state 2 solid state foliation and lineation defined by amphibolite facies assemblages that overprint and are parallel to magmatic foliation and lineation 3 folds of magmatic and solid state foliation that have hinge lines parallel to magmatic and solid state lineation and to equivalent structures in wall rocks 4 dikes that were folded and boudinaged over a wide range of rheological states with boudin necks locally filled by tonalite 5 pegmatite dikes and mineralized joints that are sub perpendicular to magmatic and solid state lineation and 6 submagmatic and high temperature solidstate ductile shear zones we suggest that many plutons emplaced during regional deformation do not preserve evidence for syntectonic deformation because of the transitory nature of the submagmatic state and the obscuring effects of postemplacement deformation syntectonic features are most likely preserved in plutons cooled at slow to moderate rates or in plutons deformed at high strain rates during emplacement the optimum conditions for preservation may occur in plutons emplaced along fault zones in the mid crust such as the mount stuart batholith and in intrusions at deeper levels that were rapidly exhumed and or intruded during the waning stages of regional deformation

scale free distribution of dead sea sinkholes observations and modeling there are currently more than 5500 sinkholes along the dead sea in israel these were formed due to the dissolution of subsurface salt layers as a result of the replacement of hypersaline groundwater by fresh brackish groundwater this process has been associated with a sharp decline in the dead sea water level currently more than one meter per year resulting in a lower water table that has allowed the intrusion of fresher brackish water we studied the distribution of the sinkhole sizes and found that it is scale free with a power law exponent close to 2 we constructed a stochastic cellular automata model to understand the observed scale free behavior and the growth of the sinkhole area in time the model consists of a lower salt layer and an upper soil layer in which cavities that develop in the lower layer lead to collapses in the upper layer the model reproduces the observed power law distribution without involving the threshold behavior commonly associated with criticality

improving sinkhole hazard models incorporating magnitude frequency relationships and nearest neighbor analysis abstract this work presents a methodology for elaborating sinkhole hazard models that incorporate the magnitude and frequency relationships of the subsidence process the proposed approach has been tested in a sector of the ebro valley mantled evaporite karst where sinkholes largely induced by irrigation practices have a very high occurrence rate 50 sinkholes km 2 yr in this area covering 10 km 2 a total of 943 new cover collapse sinkholes were inventoried in 2005 and 2006 multiple susceptibility models have been generated analyzing the statistical relationships between the 2005 sinkholes and different sets of variables including the nearest sinkhole distance the quantitative evaluation of the prediction capability of these models using the 2006 sinkhole population has allowed the identification of the method and variables that produce the most reliable predictions the incorporation of the indirect variable nearest sinkhole distance has contributed significantly to increase the quality of the models despite simplifying the modeling process by using categorical rather than continuous variables the best susceptibility model generated with the total sinkhole population and the selected method and variables has been transformed into a hazard model that provides minimum estimates of the spatial temporal probability of each pixel to be affected by sinkholes of different diameter ranges this transformation has been carried out combining two equations derived from the more complete 2006 sinkhole population one of them expressing the expected spatial temporal probability of sinkhole occurrence and the other the empirical magnitude and frequency relationships generated for two different types of land surfaces which control the strength of the surface layer and the size of the sinkholes the presented method could be applied to predict the spatial temporal probability of events with different magnitudes related to other geomorphic processes e g landslides

spatial analysis of a karst depression population clues to genesis a detailed analysis of depression spatial distribution on the parts of the western highland rim and pennyroyal plain underlain by the st louis and ste genevieve limestones indicates the presence of a depression infrastructure the major geomorphic elements of the infrastructure include depression density no km 2 doline swallet order and interdoline spacing a multigenerational diffusion and competition process model best explained 1 the presence of two lognormally distibuted depression density subpopulations 2 discrete clustered depression sets containing second order swallet dolines surrounded by first order swallet depressions 3 geomorphic competition between adjacent second order swallet dolines for runoff and catchment area and 4 a positive correlation between interdoline rim spacings of the small swallet order and the sum of their respective major axial lengths

deformation of granitoids at low metamorphic grade i reactions and grain size reduction abstract deformation and chemical reaction in granitoids at greenschist facies conditions were investigated in samples from three shear zones two from the alps corvatsch granodiorite and aiguilles rouges granite switzerland and one from eastern australia wyangala granite when examined by light and electron microscopy all show similar features of deformation that progressed from coarse parent rock through to fine grained mylonite quartz deformed plastically while both k feldspar and plagioclase fractured and recrystallized in conjunction with chemical change which had as its end point an assemblage albite quartz white mica caal silicates k feldspar and calcic plagioclase depending on fluid chemistry from the parent rock were unstable at low metamorphic grades in the presence of aqueous fluid since ca bearing plagioclase was not stable in these environments myrmekite did not replace k feldspar in any of the rocks examined recrystallization of feldspar which should perhaps be termed neocrystallization was initiated predominantly at clast margins or along microfractures that are marked by fluid inclusions and twin offsets in old feldspar grains particularly in plagioclases dislocations exist in wall like structures that are commonly associated with voids suggesting origins in microfractures these dislocations had severely limited mobility and subgrain rotation does not appear to have contributed to recrystallization we conclude that recrystallization mainly occurred via a classical nucleation mechanism with minor contributions from twin boundary migration we argue that the 450 550 c lower limit for recrystallization of feldspar referenced throughout the literature is not applicable to the rock systems under investigation and should be discarded as a universal limit microfracturing microboudinage and reaction are seen as the prerequisites for mylonite formation from coarse grained granitic rocks at low metamorphic grades see part ii of this paper neocrystallization fluid access and nucleation appear to have accompanied or immediately followed the first deformation increments and were primarily responsible for continued grain size reduction transgranular fracture was comparatively important only at the onset of deformation since the formation of shear zones in granitoids commonly takes place under conditions of low metamorphic grade in the presence of aqueous fluids in the earth s crust breakdown reactions and nucleation recrystallization in feldspars may be important influences upon localization of deformation in granitoids

sinkhole susceptibility mapping using the analytical hierarchy process ahp and magnitude frequency relationships a case study in hamadan province iran abstract since 1989 an increasing number of sinkhole occurrences have been reported in the kabudar ahang and razan qahavand subcatchments krq of hamadan province western iran the sinkhole related subsidence phenomenon poses a significant threat for people and human structures including sensitive facilities like the hamadan power plant groundwater over exploitation from the thick alluvial cover and the underlying cavernous limestone has been identified as the main factor involved in sinkhole development a sinkhole susceptibility model was produced in a gis environment applying the analytical hierarchy process ahp approach and considering a selection of eight factors each categorized into five classes distance to faults df water level decline wld groundwater exploitation ge penetration of deep wells into karst bedrock pka distance to deep wells ddw groundwater alkalinity ga bedrock lithology bl and alluvium thickness at relative weights were preliminarily assigned to each factor and to their different classes through systematic pairwise comparisons based on expert judgment the resulting sinkhole susceptibility index ssi values were then classified into four susceptibility classes low moderate high and very high susceptibility subsequently the model was refined through a trial and error process involving changes in the relative weights and iterative evaluation of the prediction capability independent evaluation of the final model indicates that 55 and 45 of the subsidence events fall within the very high and high susceptibility zones respectively the results of this study show that ahp can be a useful approach for susceptibility assessment if data on the main controlling factors have sufficient accuracy and spatial coverage the limitations of the model are partly related to the difficulty of gathering data on some important geological factors due to their hidden nature the magnitude and frequency relationship constructed with the 41 sinkholes with chronological and morphometric data indicates maximum recurrence intervals of 1 17 2 14 and 4 18 years for sinkholes with major axial lengths equal to or higher than 10 m 20 m and 30 m respectively

identification of karst sinkholes in a forested karst landscape using airborne laser scanning data and water flow analysis abstract karst sinkholes dolines play an important role in a karst landscape by controlling infiltration of surficial water air flow or spatial distribution of solar energy these landforms also present a limiting factor for human activities in agriculture or construction therefore mapping such geomorphological forms is vital for appropriate landscape management and planning there are several mapping techniques available however their applicability can be reduced in densely forested areas with poor accessibility and visibility of the landforms in such conditions airborne laser scanning als provides means for efficient and accurate mapping of both land and landscape canopy surfaces taking the benefits of als into account we present an innovative method for identification and evaluation of karst sinkholes based on numerical water flow modelling the suggested method was compared to traditional techniques for sinkhole mapping which use topographic maps and digital terrain modelling the approach based on simulation of a rainfall event very closely matched the reference datasets derived by manual inspection of the als digital elevation model and field surveys however our process based approach provides advantage of assessing the magnitude how sinkholes influence concentration of overland water flow during extreme rainfall events this was performed by calculating the volume of water accumulated in sinkholes during the simulated rainfall in this way the influence of particular sinkholes on underground geomorphological systems can be assessed the method was demonstrated in a case study of slovak karst in the west carpathians where extreme rainfalls or snow thaw events occur annually we identified three spatially contiguous groups of sinkholes with a different effect on overland flow concentration these results are discussed in relation to the known underground hydrological systems

automatic detection and imaging of diffraction points using pattern recognition hydrocarbon reservoirs are generally located beneath complex geological structures frequently such areas contain seismic diffractors that carry detailed structure information in the order of the seismic wavelength therefore the development of computational facilities capable of detecting diffractor points with a good resolution is desirable but has been a challenge in the area of seismic processing in this work we present a method for the detection of diffraction points in the common offset gather domain the method applies a two class k nearest neighbours knn pattern recognition technique to amplitudes along diffraction traveltime curves to distinguish between diffractions and reflections or noise while the method in principle requires knowledge of the migration velocity field it is very robust with respect to an erroneous model numerical examples using synthetic seismic and field ground penetrating radar gpr data demonstrate the feasibility of the technique and show its usefulness for automatically mapping diffraction points in a seismic section in our applications the method was able to detect all diffractions present in the data and did not produce any false positives

significance of a hiatus in down temperature fabric development within syn tectonic quartz diorite complexes channel islands uk detailed fabric development histories have been deduced for neoproterozoic foliated quartz diorite complexes of the channel islands uk the plutons were emplaced during regional d2 deformation magmatic fabrics formed at low crystal contents pre rheologically critical melt percent are only locally preserved due to overprinting by solid state deformation which occurred at moderate temperatures 400 550 c this is demonstrated by brittle microcracking of plagioclase and amphibole with only local ductile bending and dynamic recrystallization marginal recrystallization and myrmekite development on alkali feldspar ductile deformation of quartz to form types 2 3 ribbons quartz recrystallization by sub grain rotation associated with a slip but not c slip biotite recrystallization within micro shears and variable amphibole recrystallization the deformation histories display a distinct division between magmatic state and moderate temperature solid state deformation features with little evidence for intervening high temperature solid state fabrics this contrasts with criteria widely considered diagnostic of syn tectonic plutons which envisage development of a continuum of magmatic through high temperature solid state deformation fabrics however we consider the plutons syn tectonic and attribute the hiatus to contrasting strain and pluton cooling rates length and nature of deformation events and host rock ambient temperatures intermediate magmas emplaced at moderate to shallow levels in the crust may be more prone to develop such apparently punctuated deformation histories than sio 2 richer granitoids

identification delineation and morphometric analysis of closed terrain depressions on mars abstract the purpose of this paper is to introduce an easy to use but powerful methodology that allows closed terrain depressions on the mars landscape to be correctly identified and delineated from digital elevation models closed terrain depressions have important implications for the geology and geomorphology of mars where they have been formed by the processes of impact subsidence collapse trickle down of unconsolidated material tensional tectonic forces dissolution and erosion the application of the procedure to six test sites covering a representative range of mars landscapes shows that closed depressions are ubiquitous on mars from the southern highlands where they cover 37 of the surface to the northern lowlands where they cover 26 of the surface the minimum coverage of 9 occurs on the tharsis dome around the three giant tharsis volcanoes a power law distribution which is directly related to the fractal dimension is shown to provide a very good fit to the size distribution of mars depressions in addition to the fractal dimension several other morphometric parameters are calculated to demonstrate the use of the methodology in planetary geology the work presented here uses digital elevation models provided by the mars orbiter laser altimeter mola the resolution of which limits the identification of terrain depressions to those that have diameters greater than around 460 m the methodology is however general and can be applied to smaller scale depressions that are available in detailed digital elevation models obtained from high resolution images such as the high resolution imaging science experiment hirise mounted on the mars reconnaissance orbiter this opens up a wide range of applications using the simple but powerful methodology described in this paper

role of melt during deformation in the deep crust deformation in the deep crust is strongly influenced by the presence of melt injected melt or magma weakens the crust because strain will tend to localize where melt is present the amount of strain a pluton may accommodate is dependent on the length of time it takes for a pluton to crystallize and the strain rate for plutons that intrude into rocks which are near the solidus temperature of the melt crystallization times can be quite long 1myr partial melting of deep crustal rocks can lead to melt enhanced embrittlement this occurs because the volume change for most melting reactions is positive therefore when the rate of melt production outpaces the rate at which melt can leave the system the melt pressure increases eventually the melt pressure may become sufficiently high that the melting rocks behave in a brittle fashion and fracture conjugate sets of dilatant shear fractures filled with melt occur in migmatite from the central gneiss belt canada this suggests that melt enhanced embrittlement occurred in these rocks an expression which relates the magnitude of differential stress to the angle between conjugate dilatant shear fractures is derived assuming that migmatite has a small tensile strength differential stresses are 20 mpa in migmatitic rocks at the time melt enhanced embrittlement occurs the occurrence of melt enhanced embrittlement shows that a switch in deformation mechanism from plastic flow to cataclasis is possible in the deep crust during melting furthermore repeated episodes of melt enhanced embrittlement in migmatitic rocks may be an efficient mechanism for extracting melt from partially melted terrains

structural controls on distribution of dolines on mount anamas taurus mountains turkey abstract solution dolines are characteristic landforms on the high plateaus of the taurus mountains in this study the effects of tectonic structures drainage and slope conditions on the distribution and morphometric properties of dolines in the western part of the central taurus are explained to delimit the dolines 1 25000 scale topographic maps were used the uppermost closed contour lines were digitized as polygons and the elevation long and short axes elongation ratios orientation angles of the polygons were calculated the doline density is compared with drainage density and mean slope values a total of 111 rose diagrams were created in order to illustrate the superficial distribution of orientation as a result a total of 10 652 dolines were detected in a 711 km2 doline area and maximum density reaches 123 dolines km2 however according to the doline density two distinct regions were detected high density r1 and low density r2 correlations between drainage density slope angle and doline density are negative in the two regions according to negative correlations the drainage density is not a determinant factor in r1 while it is a determinant factor in r2 a 30 slope angle in km2 limits doline distribution on the plateau surface the orientation of all doline long axes is nw se which is parallel to the general orographic extent of mount anamas however different orientations were detected and these orientations were showed in farther sub regions according to the 111 gridded rose diagrams the overall result of this study is that the fault and joint systems that developed on the thick bedded limestone between thrust faults affected the doline density while lateral strike slip normal faults and joint systems in front of the thrust belt were more effective on the geometric shapes of dolines

solution doline development on glaciokarst in alpine and dinaric areas abstract in this study the evolution the development and the development environment of solution dolines of glaciokarst the alps and the dinarides are studied based on morphological observations partly with the help of literary data the dolines of sample sites were put into doline types giant solution doline small sized solution doline and schachtdoline the various features of the dolines belonging to different doline types were analysed and compared their size shape elongated nature and the slope angle of their side slope giant solution dolines are much more similar to the dolines of the temperate belt rather than to small sized solution dolines or schachtdolines at temperate climate giant solution dolines developed under the tree line similarly to dolines of the temperate belt and not above the tree line below the tree line the dolines grew horizontally to the effect of horizontal dissolution later in the glacials they developed laterally mainly along their longer axis by glacial erosion they got into their periglacial environment during the uplifting of the bearing area in mountains where they are absent the circumstances of their environment were not present either because the uplifting of the mountain was fast or it was covered by non karstic rock the shapes of small sized solution dolines and schachtdolines prove that their increase happened by deepening their deepening was caused by the meltwater of the snow patches of snow drifts which water does not move laterally because of the rock debris of the floor and thus solution works downwards in the features deepening and snow accumulation strengthen each other these karstic depressions are connected to the periglacial zone because treeless environment favours snow drifts if the depression is completely filled with snow in most part of the year the snow patch is wide thus dissolution affects the total width of the doline a doline schachtdoline with vertical sides and plain floor develops if snow fill is only partial in most part of the year the snow patch and thus dissolution will have a smaller area and a small sized solution doline with funnel shape develops

morphology and distribution of dolines on ultramafic rocks from airborne lidar data the case of southern grande terre in new caledonia sw pacific dolines are closed geomorphological depressions which are surface manifestations of karstic systems usually developed on limestones they also typify the morphology of the new caledonian landscape particularly on the southern massif of the main island known as massif du sud the specificity of dolines here lies in their development on ultramafic rocks they are evidences of subsidence suffosion and collapse phenomena resulting from dissolution weathering of peridotites however extensive underground drainage systems are still not yet recognized copyright 2016 john wiley sons ltd semi automatic mapping of dolines is carried out on a 148 km2 area of the massif du sud from a high accuracy lidar digital elevation model in this area 8601 dolines ranging from 1 m2 to 2 km2 are identified and morphologically characterized with precision most are small shallow and round shaped yet more complex shapes are locally observed size distribution analysis allows the setting of a threshold of 20 000 m2 above which surface processes rather than chemical weathering control doline evolution doline density analysis reveals high concentrations on flat areas where ferricrete overlies the complete weathering profile especially in the case of elevated rainy watersheds dolines are aligned and elongated along a north 135 5 major fracture direction which is inherited from the obduction of the pacific plate upper mantle in the late eocene copyright 2016 john wiley sons ltd finally we propose a pioneering morphometric typology of dolines that provides important clues as to pseudokarstic activity we define collapse bowl shaped and flat bottom dolines collapse and bowl shaped dolines are assumed to denote active pseudokarst they may widen and deepen or eventually be filled by sediments they are distinguished from flat bottom dolines that are partially to completely filled which suggests that they are associated with paleo pseudokarsts however the groundwater flow paths associated with the genesis and evolution of dolines must be clarified thus collapse and bowl shaped dolines should be hydrologically monitored copyright 2016 john wiley sons ltd

rates of processes in magmatic arcs implications for the timing and nature of pluton emplacement and wall rock deformation abstract the construction of arcs and in many cases the emplacement of plutons occur in tectonically active regions it is critical therefore to evaluate the rates of structural and magmatic processes when trying to understand the evolution of arcs and the associated pluton wall rock systems our best estimates of average rates or durations of processes in shallow to moderate level arc environments are the following 1 crystal growth rates in magma of 10 4 cm year 1 2 growth rates of metamorphic porphyroblasts between 10 5 and 10 2 cm year 1 3 long term magma supply rates of 10 1 km 3 year 1 and short term rates of up to 350 km 3 year 1 4 diapiric ascent rates for mafic plutons of 1 3 m year 1 5 cooling of plutons to ambient wall rock temperatures in 10 5 10 6 years 6 final crystallization of plutons in a small fraction of the time needed for complete cooling 7 fault displacements of 3 cm year 1 8 development of cleavages in fault zones in less than 10 6 years at strain rates of 10 13 s 1 or higher and 9 the development of regional cleavages in 10 6 years at strain rates of 10 14 s 1 these rates indicate that processes operating in magmatic arcs are relatively rapid pluton emplacement cleavage development etc occur over time spans of tens of thousands to no more than a few million years however the rate of ascent and crystallization of plutons at shallow levels is generally shorter than that needed to get large displacements on faults or widespread cleavages developed at deeper levels or in zones undergoing faster strain rates the time spans of the various processes approach one another thus plutons with otherwise similar characteristics emplaced in regions undergoing fast strain rates or at deeper crustal levels may appear quite different structurally from those emplaced at shallow levels or in regions undergoing slower strain rates comparison of these data also suggests that the rate at which wall rock deforms is the limiting factor controlling the rates of other structural processes during emplacement of plutons unless fast strain rates or multiple deformation mechanisms are considered thus emplacement mechanisms that rely on the transport of magma over 10 5 to 10 6 years are favored and need further consideration finally we argue that the structural and other characteristics of pluton wall rock systems will depend on rates of various processes involved and that these rates at the very least influence and sometimes invalidate the timing criteria previously published by us and others

fractal analysis of fracture patterns using the standard box counting technique valid and invalid methodologies abstract on the basis of results of simple box counting analysis it has been suggested in several recent publications that natural fracture patterns are fractal fractal patterns are characterized by self similarity of structure on a range of scales and provide straight line distributions on box counting plots new analysis of a fracture pattern that provided the most convincing straight line box counting curve previously published shows that the curve is non linear and therefore that the fracture pattern is not fractal non linear box counting curves are also characteristic of other natural fracture patterns analysed but spurious linear curves can be obtained if the area analysed extends beyond the mapped area