toward process based modeling of geochemical soil formation across diverse landforms a new mathematical framework we present a mathematical model that integrates geochemical and geomorphic processes responsible for soils elemental and mineralogical evolution on diverse landforms eroding to depositional to level grounds this new model combines a hillslope sediment mass balance and a soil geochemical mass balance we model soils as the sum of a physically disturbed zone pdz and the underlying physically undisturbed but chemically altered zone caz the model considers processes including the production of pdz weathering front propagation mineral specific dissolution colloidal translocation and colluvial transport thus this study serves to 1 review preexisting models of pedogenic processes and to 2 offer a framework to integrate the geochemical and geomorphic processes active in soils we further discuss the implications of our model in 1 scaling chemical weathering reactions from mineral grains to pedons to soil catenas 2 understanding the emergence of geochemical soil catenas and 3 coupling physical and chemical weathering processes

ore genesis of pb zn deposits in the nappe zone of northern tunisia constraints from pb s c o isotopic systems abstract the jalta and jebel ghozlane ore deposits are located in the extreme north of tunisia within the nappe zone the mineralization of jalta hosted in triassic dolostones and the overlying mio pliocene conglomerates consists of abundant galena barite and cerussite with accessory sphalerite pyrite and jordanite at jebel ghozlane large pb zn concentrations occur in the triassic dolostones and eocene limestones the mineral association consists of galena sphalerite barite and celestite and their oxidation products cerussite smithsonite and anglesite lead isotope ratios in galena from both districts are relatively homogeneous 206 pb 204 pb 18 702 18 823 207 pb 204 pb 15 665 15 677 208 pb 204 pb 38 725 38 875 the 34 s values for sulfates from both areas 12 2 to 16 2 at jalta and 14 3 to 19 4 at jebel ghozlane are compatible with a derivation of sulfur from marine sulfates possibly sourced from the triassic evaporites the 34 s values of the sulfides have a range between 10 and 12 5 at jalta and between 9 1 and 22 1 at jebel ghozlane the large range of values suggests reduction of the sulfate by bacterial and or thermochemical reduction of sulfate to sulfur the high 34 s values of sulfides require closed system reduction processes the isotopically light carbon in late calcites 6 3 to 2 5 and authigenic dolomite 17 6 suggests an organic source of at least some of the carbon in these samples whereas the similarity of the 18 o values between calcite 24 8 and the authigenic dolomite 24 7 of jalta and their respective host rocks reflects oxygen isotope buffering of the mineralizing fluids by the host rock carbonates the secondary calcite isotope compositions of jalta are compatible with a hydrothermal fluid circulation at approximately 100 to 200 c but temperatures as low as 50 c may be indicated by the late calcite of jebel ghozlane 18 o of 35 9 given the geological events related to the alpine orogeny in the nappe zone nappe emplacement bimodal volcanism and reactivation of major faults such as ghardimaou cap serrat and the neogene age of the host rocks in several localities a late miocene age is proposed for the pb zn ore deposits considered in this study remobilization of deep seated primary deposits in the paleozoic sequence is the most probable source for metals in both localities considered in this study and probably in the nappe zone as a whole

tectonic controls of the right lateral burro negro tear fault on paleogene structure and stratigraphy northeastern maracaibo basin the northeastern maracaibo basin in western venezuela was deformed by paleogene thrusting and an associated tear fault burro negro right lateral strike slip fault zone related to paleogene oblique collision between the caribbean and south american plates two different tectonic models have been previously proposed for the thick paleogene depocenter located along the northeastern margin of the maracaibo basin the first model proposes that the depocenter is a foreland basin controlled by southwestward directed overthrusting during a late paleocene middle eocene oblique collision between the caribbean and south american plates the second model supported by data presented in this study proposes that the asymmetric paleogene maracaibo sedimentary wedge was controlled by strike slip displacement along a right lateral tear fault separating southeast directed thrust sheets to the east lara nappes from a more stable platform area to the west maracaibo basin regional seismic lines recorded to 5 s two way traveltime reveal the structure of the asymmetric paleogene depocenter in the northeastern part of the maracaibo basin the approximately 100 km 62 mi long burro negro fault is a right lateral strike slip fault separating less deformed inner to outer shelf rocks of the western maracaibo basin from highly deformed deep marine rocks of the eastern maracaibo basin seismic lines northeast of the burro negro fault zone show elongate subsurface basins bounded by partially inverted reverse and strike slip faults filled with about 3 km 1 8 mi of oligocene and miocene clastic marine sedimentary rocks structural highs of eocene rocks are characterized at depth on seismic reflection lines by chaotic seismic reflections that underlie the more coherently stratified oligocene and miocene subbasins we interpret these structural highs as steeply dipping fault zones and shale diapirs activated during eocene oligocene oblique plate convergence the geology and overall structural configuration of the northeastern maracaibo basin and the burro negro fault zone support its origin as a right lateral tear fault in our model the burro negro fault zone accommodated southeastward migration of the thrust front in the deep water area east of the fault in the present day falcn region the paleogene clastic wedge of the maracaibo basin exhibits many common features of a classic foreland basin including onlap onto an arch or forebulge located near the center of the present day lake maracaibo this paleogeographic coincidence of the burro negro fault zone and the maracaibo shelf edge suggests that the paleotrend of the south american passive margin prior to collision was serrated in map view west to east migration of the caribbean south america oblique collision formed progressively younger parallel tear faults to the east of the maracaibo basin that may have formed by the same tectonic process as the burro negro fault zone

landform classification and soil distribution in hummocky terrain saskatchewan canada this study presents a classification of distinct three dimensional landform elements and examines the relationship between these landform elements and selected soil morphological properties of udic boroll soils in southern saskatchewan canada the classification is based on defined ranges of three criteria derived from topographic data gradient profile downslope curvature and plan across slope curvature seven landform elements are recognized convergent shoulders divergent shoulders convergent backslopes divergent backslopes convergent footslopes divergent footslopes and level elements all of the elements are easily identified in the field the thicknesses of a horizons and depths to calcium carbonate of the soils were consistently greater in convergent versus divergent elements in the same profile group e g shoulders and showed an overall increase in the sequence shoulders backslopes level footslope elements distinct groups of elements emerge from a statistical analysis of the differences between individual and bivariate means of soil morphological properties associated with each landform element the differences in soil properties among the elements can be largely explained by differences in water movement and distribution in hillslope systems the results of the study highlight the need to consider land surface morphology during the development of research designs for soil related studies

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

structural interpretation of thrust fault related landforms on mercury using earth analogue fault models abstract the yakima fold province has often been referenced as an earth analogue to thrust fault related landforms on many solar system bodies including mars the moon and mercury the asymmetric ridges of deformed flood basalts in this region evoke the morphology and topographic expression of the landforms observed in the smooth plains units of mercury observed similarities have supported the interpretation that thrust faults and folds comprise both sets of landforms however this is an incomplete analogy recent modeling efforts have revealed that the terrestrial landforms developed over millions of years with vertical uplift associated with each landform accumulating on multiple faults and accommodated by large folds these studies highlight the important role that folding plays in accommodating crustal shortening work presented here uses the structural geometries and folding styles from the yakima fold province as a framework for constructing ten three dimensional models of thrust fault related landforms in smooth plains units near suisei planitia on mercury which traditionally would have been classified as wrinkle ridges based on appearance and some aspects of morphology forward modeling of topography revealed that multiple faults and folds are necessary to reproduce complex topographic features folding was found to account for 50 of vertical uplift associated with the landforms and without considering folding shortening accommodated by the landforms was underestimated by 61 to 88 studies which use thrust fault related landforms as proxies for stress and strain must therefore consider the effect of folding on these estimates and their associated effect on tectonic and thermal histories

geometry kinematics and displacement characteristics of tear fault systems an example from the deep water niger delta we use three dimensional seismic reflection data and new map based structural restoration methods to define the displacement history and characteristics of a series of tear faults in the deep water niger delta deformation in the deep water niger delta is focused mostly within two fold and thrust belts that accommodate downdip shortening produced by updip extension on the continental shelf this shortening is accommodated by a series of thrust sheets that are locally cut by strike slip faults through seismic mapping and interpretation we resolve these strike slip faults to be tear faults that share a common detachment level with the thrust faults acting in conjunction these structures have accommodated a north south gradient in westward directed shortening we apply a map based restoration technique implemented in gocad to restore an upper stratigraphic horizon of the late oligocene and use this analysis to calculate slip profiles along the strike slip faults the slip magnitudes and directions change abruptly along the lengths of the tear faults as they interact with numerous thrust sheets the discontinuous nature of these slip profiles reflects the manner in which they have accommodated differential movement between the footwall and hanging wall blocks of the thrust sheets in cases for which the relationship between a strike slip fault and multiple thrust faults is unclear the recognition of this type of slip profile may distinguish thin skinned tear faults from more conventional deep seated throughgoing strike slip faults

geometrical modeling of fault related folds a pseudo three dimensional approach abstract area balanced cross sections of ramp anticlines and tip line folds in thin skinned fold thrust belts can be quantitatively constructed using plane strain fault bend and fault propagation fold models cross sections alone however are somewhat inadequate for interpreting along strike changes in thrust related fold geometry complex interplay between along strike changes in fault slip and fault shape determines a range of geometric configurations which are difficult to visualize without the aid of quantitative three dimensional models we extend conventional two dimensional folding theories into the third dimension by allowing for continuous variations in fault slip and fault shape along strike geometric equations relating map view angles between fold axial surface traces are derived for a case assuming a uniform fault geometry and an along strike displacement gradient the resulting folds possess no unique fold axis but rather are characterized by multiple fold hingelines each corresponding to bends in the fault for typical displacement gradients observed in the field analysis of the models suggests that discernible differences exist between map patterns of fault bend folds and fault propagation folds whereas little difference exists between map patterns of similar and parallel fault bend folds map view angles between axial surface traces for parallel fault bend folds and fault propagation folds are a function of both ramp cutoff angle and fault slip whereas these same angles for similar fault bend folds are solely a manifestation of fault slip examples assuming uniform shortening and continuously varying fault geometry along strike are also presented fault geometry is varied along strike to simulate oblique and lateral ramps depending upon model type and fault shape parameter modified resulting folds exhibit either cylindrical or non cylindrical fold geometries closure is generated by a decrease in fold amplitude where there is a decrease in ramp cutoff angle along strike or where a fault laterally cuts up section in either instance closure develops without varying shortening along strike model map patterns resemble actual thrust related fold geometries and can be compared to maps of real structures to help predict subsurface geology

palinspastic restoration of the anniston transverse zone in the appalachian thrust belt alabama abstract transverse zones are cross strike alignments of cross strike linking structures lateral ramps transverse faults and displacement transfer zones in foreland thrust belts cross strike links constitute one component of a three dimensional system of fault surfaces connecting strike parallel structures frontal ramps and detachment flats both geometrically and kinematically three dimensional palinspastic restoration provides the basis to consider causes of cross strike alignments of cross strike links into transverse zones as well as the role of transverse zones in kinematic history the anniston transverse zone in the appalachian thrust belt in alabama southeastern united states exemplifies the types and distribution of cross strike links within a transverse zone palinspastic reconstruction of the anniston transverse zone relies on matching hanging wall footwall pairs of frontal and lateral ramps for geometric balance in three dimensions in palinspastic map and cross section views cross strike links within the anniston transverse zone are systematically distributed across strike from hinterland to foreland as domains of lateral ramps transverse faults and displacement transfer zones in response to variations in depth to basement beneath the thrust belt and variations in thickness of decollement host weak rocks contrasting structural profiles characterize the thrust belt on opposite sides of the anniston transverse zone as a result of abrupt along strike changes at the cross strike alignment of cross strike links the anniston transverse zone is aligned with a northwest striking basement fault that offsets the boundary faults of the birmingham basement graben suggesting kinematic partitioning within the advancing thrust sheets at a stress concentrator the northwest striking basement fault separates domains of contrasting structural profiles of basement fault systems differing elevations of top of basement and differing thicknesses of the regional decollement host weak layer in the lower part of the sedimentary succession above basement rocks

structural geology of a classic thrust belt earthquake the 1999 chi chi earthquake taiwan mw 7 6 abstract we document the structural context of the 1999 chi chi earthquake m w 7 6 in western taiwan which is one of the best instrumented thrust belt earthquakes the main surface break and large slip 3 10 m is on two segments of the shallow otherwise aseismic bedding parallel chelungpu sanyi thrust system which shows nearly classic ramp flat geometry with shallow detachments 1 6 km in the pliocene chinshui shale and mio pliocene kueichulin tungkeng formations however rupture is complex involving at least six faults including a previously unknown deeper thrust 8 10 km on which the rupture began we compare the coseismic displacements with a new 3d map of the chelungpu sanyi system the displacements are spatially and temporally heterogeneous and well correlated with discrete geometric segments of the 3d shape of the fault system geodetic displacement vectors are statistically parallel to the nearest adjacent fault segment and are parallel to large scale oblique fault corrugations the displacement magnitudes are heterogeneous at several scales which requires in the long term other non chi chi events or significant aseismic deformation the chelungpu thrust has a total displacement of 14 km but the area of largest chi chi slip 10 m is on a newly propagated north chelungpu chinshui detachment 0 3 km total slip which shows abnormally smooth rupture dynamics

approach and application of industry software to structural investigations in the subsurface of mercury s thrust fault related landforms abstract historical efforts to model structures underlying planetary tectonic landforms have prioritized characterizing the dips depths and orientations of faults vertical displacement of rock along faults has been assumed to produce observed positive topography model derived fault parameters and values for fault displacement and strain have been estimated and these estimates have then been used to describe strain accumulated within regions of a planet or within entire planetary lithospheres previous modeling efforts have used finite element methods to reproduce topography associated with structure related landforms with acceptable models being determined through statistical best fit testing the approach presented in this work describes how software originally designed for industrial applications can be used in combination with the interpretation of topography and imagery to inform our understanding of the subsurface complexity of structures including faults and folds through a case study of ten structures in a smooth plains unit on mercury a detailed approach is provided for three dimensional modeling of subsurface faults and folds working with qualitative and semi quantitative criteria for acceptable or successful models and using those models to determine the relative importance of faulting and folding on topographic development through these details this work seeks to break through the black box often associated with modeling with the potential to support genuinely reproducible research

morphometric analysis of debris flows and their source areas using gis important factors for the initiation of debris flows include available loose sediment torrential rainfall and topographic conditions the objective of this study is to identify topographic features of debris flows and conditions favorable for debris flow initiation based on geomorphological analyses of 11 river basins in northern and central taiwan morphometric indices were derived from 10 m grid digital terrain models before and after debris flow events using gis the indices include the stream power index spi topographic wetness index twi sediment transport capacity index elevation relief ratio form factor effective basin area and slope gradient the results show that debris flows tend to initiate from steep slopes or landslides with higher twi values debris flows are expected in basins with higher spi and twi basins with lower slope gradients and spi but higher twi may also have a high potential for debris flow spi changes most significantly due to a debris flow event particularly in steep basins

three dimensional geometry and interference of fault bend folds examples from the ponga unit variscan belt nw spain abstract examples of the three dimensional geometry and interference patterns between fault bend folds occur in the ponga unit of the variscan cantabrian foreland thrust and fold belt of nw spain the ponga unit consists of several e directed thrust sheets with a cumulative displacement of 93 km which were emplaced during upper westphalian stephanian time two major lateral ramps developed in the basal thrust of the ponga unit reaching 15 and 20 km in length respectively and some 3 km in height lateral structures are also common within the hangingwall thrust sheets the three dimensional staircase trajectories of thrust faults together with the tectonic superposition of thrust sheets has produced a complex interference pattern of fault related folds most map scale folds formed as fault bend folds related to interference between frontal and lateral ramps fold geometry and size varies depending on the geometry and size of the associated thrust ramp and flat the axial traces are grouped into lateral and frontal sets which are sub parallel or sub perpendicular to the tectonic transport direction respectively corner folds form with plunging axes at the intersections of frontal and lateral ramps and generally link pairs of frontal lateral folds they have relatively short axial traces that are oblique to the tectonic transport direction fold plunge varies due to the superposition of lateral and frontal structures of a thrust fault and also depends on the geometry of subsequent thrusts in the footwall the final geometry of frontal folds in the ponga unit are not only the result of the bending mechanism but have been modified by simple shear parallel to the emplacement direction major lateral structures have been reactivated as reverse faults and are locally overturned due to post emplacement north south compression

spatial arrangement of decollements as a control on the development of thrust faults abstract we used two dimensional finite element models to explore different configurations of weak layers in undeformed sedimentary sequences to investigate the occurrence of three characteristic types of thrust configurations ramp flat imbricate and duplex in our models we embedded two low friction weak layers with a finite spatial extent in a sequence of stronger rock these two weak layers were initially horizontal were separated vertically by 1 km and were arranged in three different relative positions to each other when the models were deformed and these weak layers developed into decollements they interacted to produce one of the three types of thrust faults as a function of their initial configurations when the tips of weak layers were separated by a large gap 10 km only the lower level decollement became active producing imbricate thrusts when the two weak layers overlapped for a large distance 10 km they simultaneously became active decollements producing duplexes in the overlapped zone when the gap or overlap was small

tectonic style and structural analysis of the puebla de guzman antiform iberian pyrite belt south portuguese zone sw spain

differential transport and continuity of thrust sheets abstract structural geologists long have strived to establish basic tenets describing the interaction between thrust displacement and lateral extent of thrust sheets individual non metamorphic thrust sheets can be partitioned into segments that exhibit linear variations in displacement along strike the differential transport between endpoints of each segment define an along strike bulk shear angle which describes the spatial rate of change in displacement along the length of the fault empirical measurements of differential transport angles for continuous thrust sheets from different north american fold thrust belts yield bulk shear angles that do not exceed 35 40 without formation of tear faults these values might thus be considered a limit for coherent behavior of continuous non metamorphic thrust sheets thereby providing constraints on three dimensional interpretations of fold thrust belts

revisiting the hubbert rubey pore pressure model for overthrust faulting inferences from bedding parallel detachment surfaces within middle devonian gas shale the appalachian basin usa abstract both bedding parallel slickensides and cleavage duplexes are forms of mesoscopic scale detachment faulting populating black marcellus and geneseo burket and intervening gray mahantango shales of the middle devonian a section known for abnormal pore pressure below the appalachian plateau the abundance and the orientation of slickensides and cleavage duplexes in the more organic rich black shale relative to gray shale suggests that maturation related abnormal pore pressure facilitates detachment a mesoscopic manifestation of the hubbert rubey pore pressure model for overthrust faulting the former are discrete slip surfaces whereas the latter consists of nested anastomosing slip surfaces either cutting through bedding or on disrupted bedding surfaces stacked as mesoscopic versions of thrust duplexes cleavage duplexes are between a few cm and over 1 m thick with their hanging walls commonly transported toward the appalachian foreland regardless of local limb dip cleavage duplexes are most common near the stratigraphic maximum flooding surface the organic rich section most prone to develop maturation related pore pressure in the middle devonian gas shales bedding parallel slickensides are somewhat more evenly distributed in the black shale but also found in overlying gray shale in both black and gray shales slickensides are more abundant on the limbs of folds an indication of pore pressure related flexural slip folding on the macroscopic scale the pine mountain block of the southern appalachian mountains was enabled by a basal detachment cutting along the upper devonian chattanooga black shale which has a thermal maturity sufficient for the generation of abnormal pore pressure the pine mountain block is a large scale overthrust showing little evidence of collapse of the hinterland side a credible example of a pore pressure aided overthrust fault block of the type envisioned by the hubbert rubey model

hydropedology of a mildly arid loess covered area southern israel extensive loess covered areas characterize the mildly arid areas of western israel where average annual rainfall is 280 mm hydrological data point to a peculiar hydrological behavior of the ephemeral streams the frequency of sporadic flash floods is very high however even in extreme rain events peak discharges are extremely low hydrographs are usually characterized by very steep rising and falling limbs representative of saturated areas extending over a limited part of the watershed following this observation we advanced the hypothesis that storm channel runoff originated in the channel itself with negligible contribution from the adjoining hillslopes the study was based on two complementary approaches the hydrological approach was based on the detailed analysis of rainfall runoff relationships in a small watershed 11 km2 and on the analysis of the hydrological characteristics of the drainage network the second approach was based on the toposequence concept several boreholes were dug along a hillslope 400 m long chemical data obtained show no significant difference in the downslope direction similar results were also obtained for the particle size distribution and soil moisture content data obtained perfectly fit the concept of partial area contribution as it presents an extreme case of hydrological discontinuity at the hillslope channel interface the lack of pedological trends in the downslope direction is an additional indication of the limited connectivity between the hillslopes and the adjoining channel the limited connectivity is attributed to the prevalence of low rain intensities in the study area the present study is also relevant to our understanding of pedological processes in dry land areas the high frequency of intermittent low intensity rainstorms limits runoff generation and flow distances and casts doubt on the general application of the toposequence approach this article is protected by copyright all rights reserved

quantitative analysis of land surface topography land surface topography significantly affects the processes of runoff and erosion a system which determines slope aspect and curvature in both the down slope and across slope directions is developed for an altitude matrix also the upslope drainage area and maximum drainage distance are determined for every point within the altitude matrix a fortran 66 program performs the analysis

an empirical geomorphology based approach to the spatial prediction of soil thickness at catchment scale 1 catchment modeling in areas dominated by active geomorphologic processes such as soil erosion and landsliding is often hampered by the lack of reliable methods for the spatial estimation of soil depth in a catchment soil thickness h can vary as a function of many different and interplaying factors such as underlying lithology climate gradient hillslope curvature upslope contributing area and vegetation cover making the distributed estimation of h challenging and often unreliable in this work we present an alternative methodology which links soil thickness to gradient horizontal and vertical slope curvature and relative position within the hillslope profile while the relationship with gradient and curvature should reflect the kinematic stability of the regolith cover allowing greater soil thicknesses over planar and concave areas the distance from the hill crest or from the valley bottom accounts for the position within the soil toposequence this last parameter is fundamental points having equal gradient and curvature can have significantly different soil thickness due to their dissimilar position along the hillslope profile the proposed model has been implemented in a geographic information system environment and tested in the terzona creek basin in central italy results are in good agreement with field data mean absolute error is 11 cm with 8 5 cm standard deviation and average errors are lower than those obtained with other topography based methods where mean absolute error ranges from 47 cm for a model based on curvature position and slope gradient to 94 cm for a model based solely on slope gradient as a further test the predicted soil thickness was used to determine derived quantities such as the factor of safety for landsliding potential our model when compared to other empirical methods returns the best results and therefore can improve the prediction of soil losses and sediment production when utilized in conjunction with hydrological and landsliding models

mineralogy bulk and rare earth element geochemistry of massive sulphide associated hydrothermal sediments of the brunswick horizon bathurst mining camp new brunswick massive sulphides are spatially and temporally associated with iron formation if and other hydrothermal sedimentary rocks in the vicinity of the brunswick no 12 brunswick no 6 and austin brook deposits bathurst mining camp sulphide carbonate oxide and silicate predominant if is present carbonate predominant if is best developed in and around the brunswick no 12 deposit whereas hematite bearing if is absent here but prominent in the austin brook brunswick no 6 area the if is composed dominantly of si co2 fe mn and ca minor constituents include mg p ti al and s statistically significant interelement correlations between eu fe mn pb zn cd au ca sr ba p co2 and s indicate that these elements were precipitated from hydrothermal fluids vented onto the seafloor positive interelement correlations between si ti al mg k zr rare earth elements ree s except eu se v y yb co ni and cr reflect the presence of detrital clastic mafic and aluminosilicate minerals and

three dimensional geometry and kinematic evolution of the pine mountain thrust system southern appalachians the pine mountain thrust system is the westernmost major structure in the southern appalachian valley and ridge in virginia tennessee and kentucky surface subsurface and seismic reflection data have been integrated to construct a series of balanced cross sections and interpret the three dimensional geometry and kinematic evolution of the structure the structure is subdivided into three main areas on the basis of structural style in the southwestern and northeastern areas the structure consists of a simple ramp related anticline the powell valley anticline related to a ramp in the pine mountain thrust from the cambrian rome to the devonian chattanooga formation in the central oil producing area the pine mountain thrust is exposed in several erosional fensters as a result of folding by one or more subthrust imbricates here the pine mountain thrust develops a double ramp geometry with an intermediate flat in the cambrian maynardville formation the structure varies from a system of overlapping anticlines in the brooks and martin creek fenster sections to two anticlines separated by an intermediate syncline in the bethel and sulphur springs fenster sections to a partially overlapping duplex imbricate system in the big stone gap section the total shortening associated with the pine mountain thrust system decreases from about 70 000 ft 21 3 km at the southwest end to less than 10 000 ft 3 0 km at the northeast end in the central fenster area the total shortening is distributed between the pine mountain thrust and its subthrust imbricates the structural elevations in both the pine mountain and bales i sheets are greatest in the central fenster area the greatest structural elevations in the bales i sheet are in the rose hill and ben hur oil fields palinspastic restorations of the thrust system and the construction of detailed fault maps indicate that variations in structural geometry and shortening along strike are accommodated by interactions between thrust faults and oblique ramps or tear faults the variations in three dimensional geometry can be explained in terms of combinations of three main mechanisms unequal hanging wall displacements over a single footwall ramp equal displacements over a footwall ramp displaced along an oblique ramp and displacement of part of a footwall ramp due to movement on one or more frontal thrusts

soil landscape modeling across a physiographic region topographic patterns and model transportability abstract soil landscape modeling techniques have been developed as a quantitative method to predict patterns of soil properties from observed patterns in soil forming factors however transportability of these models to unsampled landscapes is unknown our objective was to develop quantitative soil landscape models for multiple study sites and examine the similarity of these quantitative models and therefore the similarity of soil landscape relationships among areas with similar soils we collected high resolution digital elevation models dem for six study sites across the pennyroyal physiographic region of kentucky and for each study site used terrain attributes derived from the dem to collect discrete soil samples using a stratified random sampling design for morphological physical and chemical characterization for three of these sites we examined the inherent differences in terrain attributes among sites and developed quantitative soil landscape models that predict the spatial patterns in a horizon depth surface soil organic carbon content and surface sand and silt content the other three sites were used to test the transportability of these models terrain attribute distributions differ significantly among study sites with regional terrain attributes upslope contributing area topographic wetness index being more similar among fields than local terrain attributes slope gradient slope curvature predictive models explained from 28 to 67 of the variation in soil properties the terrain attributes that best predicted soil variability were similar across all three fields used for model development with slope gradient elevation slope curvature and upslope contributing area appearing in most of the models however applying models from one field to other fields within the same physiographic region produced inconsistent results in general prediction quality decreased with distance from the site of model development further sampling modeling and validation at additional field sites are required to properly establish model transportability

surface microtopography and soil penetration resistance associated with shrub patches in a semiarid rangeland the surfaces of hillsides in semiarid regions are characterized by vegetative patchiness and an associated pattern of soil characteristics in a semiarid patchy rangeland in the northern negev region of israel the pattern of ground surface microtopography and soil penetration resistance were investigated along transects centred on randomly selected shrubs of sarcopoterium spinosum each transect comprised five segments on the hillslope axis upslope us and downslope ds of the central stem cluster of the shrub patch immediately upslope of the shrub tr an upper intershrub ui segment above tr and a lower intershrub li segment below ds significant differences were found among the different segments with regard to both slope and soil penetration resistance segment us had a relatively shallow slope 9 0 in average and the deepest penetration depth 20 5 mm segment ds had the steepest slope 21 0 and a relatively deep penetration depth 16 4 mm segments ui and li had intermediate values for both slope 15 1 and 13 4 respectively and penetration depth 10 5 and 9 8 mm a spatial relationship between the shrub patches and grazing was found segment tr immediately above the shrub tended to be a flock trampling route and had the lowest values of both slope 5 1 and penetration depth 6 1 mm a conceptual model was proposed to explain these results it suggests that under the prevailing conditions of the study site these relationships regulate the redistribution of soil resources on the hillside

fault bend folding as an end member solution of double edge fault propagation folding fault bend folding is the most commonly used kinematic mechanism to interpret the architecture and evolution of thrust related anticlines in thrust wedges however its basic requirement of an instantaneous propagation of the entire fault before hangingwall deformation limits its kinematic effectiveness to overcome this limitation we used the interdependence between fold shape and fault slip vs propagation rate s p ratio implemented in double edge faultpropagation folding we show that very small s p values produce fault propagation anticlines that when transported

optimisation of relief classification for different levels of generalisation abstract relief plays an important role in the spatial and temporal distribution of soil water and matter transport processes each landscape can be segmented into different landform elements based on a digital elevation model these landforms contain characteristic properties in terms of energy and material balance several algorithms are available to classify landscapes at different scales however lack of knowledge exists concerning the applicability of relief parameters for landscape stratification for different generalisation levels of underlying data the objective of this study was to develop a method for agricultural landscapes to classify landform elements across a series of elevation datasets with different spatial resolutions a non linear parameter optimisation algorithm was coupled with a relief classification scheme to optimize four classification parameters with regard to environmentally sensitive landforms shoulder and footslope input datasets were based on a lidar scan and topographic maps the magnitude of the optimized relief parameters decreased with decreasing map scale from 1 10 000 to 1 100 000 or increasing contour line interval the main conclusion is that if one set of classification rules for a specific landscape was determined for a high resolution dataset at a small subset it could be applied for larger areas even if only coarser digital elevation model information were available

spatial delineation of organic carbon rich colluvial soils in chernozem regions by terrain analysis and fuzzy classification abstract colluvial soils are considered to be the direct result of accelerated soil erosion resulting in accumulation of humus rich soil material in terrain depressions and base parts of slopes the organic carbon concentration in these soils and their depth make them an important organic carbon storage mapping the colluvial soils therefore represents an important contribution in total carbon stock estimation a method of delineating colluvial soils is proposed by applying a combination of high resolution digital elevation model analysis and detailed field survey two models based on fuzzy classification of soil units were created using different topographic derivatives as the only input parameters to predict the colluvial soil area on a morphologically diverse study site in the southern moravia czech republic the model that considers only the derivatives with a strong relationship to colluvial soil occurrence reached 71 accuracy in colluvial area delineation while the model combining six commonly used derivatives showed less favorable results the main advantage of the method lies in a low demand of input soil data and its relatively high accuracy

a duplex model for the eastern cape fold belt evidence from the palaeozoic witteberg and bokkeveld groups cape supergroup near steytlerville south africa abstract the eastern part of the cape fold belt near steytlerville south africa reveals a typical pattern of numerous north verging thrust faults and associated folds interpreted as part of a large duplex structure that formed along the southern margin of gondwana during the late palaeozoic steeply dipping fore and backthrusts occur in the bokkeveld group middle cape supergroup where strata are composed of predominantly argillaceous rocks whereas in the more arenaceous witteberg group upper cape supergroup there are fewer recognizable and less closely spaced thrusts open style folds characterize areas in which the bokkeveld group crops out but in areas of witteberg outcrop folds especially those adjacent to thrusts are often overturned in spite of a general absence of marker horizons a displacement of at least 500 metres can be inferred for one prominent thrust the jackalsbos thrust this fault the northernmost in the area investigated is probably the sole thrust in the duplex structure linked through southward dipping imbricates to a projected roof thrust the baviaanskloof thrust cropping out immediately south of the study area displacements on imbricates within the duplex are difficult if not impossible to measure but the net effect is certainly accumulative and incremental truncation by a roof thrust and subsequent erosional processes may explain why so few of the many thrusts so far identified in the eastern part of the fold belt can be successfully mapped and their displacements measured normal and strike slip faults less common than thrust faults formed during extensional tectonism related to the breakup of gondwana during the mesozoic

the effects of dem resolution and neighborhood size on digital soil survey terrain characteristics such as slope gradient slope aspect profile curvature contour curvature computed from digital elevation model dem are among the key inputs to digital soil surveys based on geographic information systems gis these terrain attributes are computed over a neighborhood spatial extent the objective of this research was to investigate the combined effect of dem resolution and neighborhood size on digital soil surveys using the soil landscape inference model solim approach the effect of neighborhood size and dem resolution on digital soil survey was examined through computing the required terrain attributes using different neighborhood sizes from 3 to 54 m for 3 6 9 12 18 and 27 m resolution dem these attributes were then compiled and used to digitally map soils using the solim approach field work completed on a hillslope in dane county wi in the summer of 2003 was used to validate each of the solim derived soil surveys for accuracy the results of the soil survey validations suggest that there is a range of neighborhood sizes that produces the most accurate results for a given resolution dem this range of neighborhood sizes however varies from landscape to landscape when the soils on a gently rolling landscape were mapped the neighborhood sizes that produced the most accurate results ranged from about 33 48 m when soils on short steep backslope positions were mapped the neighborhood size values that produced the most accurate results range from about 24 36 m this paper also shows that it is not always the highest resolution dem that produces the highest accuracy knowing which dem resolution and neighborhood size combinations produce the most accurate digital soil surveys for a particular landscape will be extremely useful to users of gis based soil mapping applications

identification of the spatial distribution of soils using a process based terrain characterization abstract a simple process based terrain characterization model was developed to identify the occurrence of soils over a complex landscape its basic proposition is that soil distribution can be most efficiently identified by the separation of pedogeomorphological units where similar hydrological geomorphological and pedological processes occur the proposed model is a three dimensional extension of the nine unit soil landscape model the two dimensional conceptual and qualitative model is reinterpreted in terms of continuity equations describing the distribution of soil materials over hillslopes and is implemented in a geographical information system gis through the analysis of a raster digital elevation model dem the application of this model at the empire prairie in southern wisconsin usa shows a good agreement with the results of a soil investigation the difficulty in modeling the diverse geomorphological and pedological processes at low lying slope positions and the influence of relict pedological features on contemporary soil formation however remain unsolved this model can consider the spatial variability of soils both at the continuous and discrete scales and is easily transferable to other slopes in a predictive manner it is further expected to provide a quantitative tool to characterize surface topography in terms of process identification and resource survey and also a priori information for spatially distributed ecological and environmental models

measuring the relative topographic position of archaeological sites in the landscape a case study on the bronze age barrows in northwest belgium abstract local topography is an important parameter determining the erection of a certain type of site on a certain location in the landscape despite the importance of topography in archaeological landscape research the role of local topography has remained rather unexplored compared to other specific topographic parameters such as slope aspect curvature or visibility therefore three methods to assess the relative topographic position of sites are applied and discussed here the bronze age barrow dataset of northwest belgium acts as the subject for this methodological case study first elevation percentile calculates the area that is lower than the central point within a predetermined neighborhood secondly difference from mean elevation measures the relative topographic position of the central point as the difference between the elevation of this central point and the mean elevation within a predetermined neighborhood and finally deviation from mean elevation calculates the relative topographic position of the central point as the difference from mean elevation divided by the standard deviation of elevation within a predetermined neighborhood these three methods each with their advantages and disadvantages prove to be an added value for archaeological landscape research

first balanced cross section across the taurides fold thrust belt geological constraints on the subduction history of the antalya slab in southern anatolia eastern mediterranean subduction accommodated africa eurasia convergence since mesozoic time and produced multiple subducted slab fragments in the mantle below anatolia these included the north dipping cyprus and ene dipping antalya slabs which are currently separated by an upper mantle slab gap segmentation of these slabs and associated mantle flow may have contributed to 400 km of post to middle eocene plate convergence was accommodated between the taurides and its beydaglari platform foreland and instead must have been accommodated south of beydaglari the associated southward plate boundary jump separated the antalya slab from the african plate and the cyprus slab the isolated antalya slab was left in an intraplate setting and is probably still attached to beydaglari today we suggest the continental composition of the antalya slab may have prevented its detachment finally the gap between the antalya and cyprus slabs existed since at least eocene time their decoupling likely did not contribute to late neogene central anatolian plateau uplift

interpretation of the last chance thrust death valley region california as an early permian decollement in a previously undeformed shale basin abstract the last chance thrust discontinuously exposed over an area of at least 2500 km2 near the south end of the cordilleran foreland thrust belt in the death valley region of east central california is controversial because of its poorly constrained age and its uncertain original geometry and extent we interpret this thrust to be early permian in age to extend throughout a sedimentary basin in which deep water mississippian shale overlain by pennsylvanian and earliest permian limestone turbidites accumulated to represent about 30 km of eastward displacement and to be related to convergence on a northeast trending segment of the early permian continental margin last chance deformation occurred between the times of the antler and sonoma orogenies of late devonian early mississippian and late permian ages respectively and followed early to middle pennsylvanian truncation of the continental margin by transform faulting in the western part of the mississippian shale basin in east central california the originally recognized exposures of the last chance thrust show neoproterozoic and early paleozoic strata above lower plate mississippian shale farther east faults subparallel to bedding above below and within the mississippian shale are interpreted to mark the thrust zone and to represent a regional decollement at the eastern margin of the basin upper plate thrust slices of deep water late paleozoic strata are interpreted to have piled up against the margin of the mississippian carbonate shelf to form a large antiformal stack above the lee flat thrust which we regard as the easternmost exposure of the last chance thrust thrust loading depressed the western part of the shelf creating a new sedimentary basin in which about 3 5 km of younger early permian deep water strata were deposited against the antiformal stack later probably in the late permian other thrusts including the inyo crest thrust which was subsequently overlapped by early to middle triassic marine strata cut across the last chance thrust we interpret the last chance thrust as similar in many ways to appalachian type decollements in which the zone of thrusting is localized along a shale interval the last chance thrust however has been dismembered during later geologic events so that its original geometry has been obscured our model may have unrecognized analogs in other structurally complex shale basins in which the initial deformation was along a major shale unit

making use of the world reference base diagnostic horizons for the systematic description of the soil continuum application to the tropical mountain soil landscape of southern ecuador abstract the world reference base for soil resources wrb fao iuss working group wrb 2007 at present does not acknowledge the spatial soil continuum but provides a sound basis to do so using methods from statistical learning theory to develop digital soil maps is much more efficient and precise while regionalising soil diagnostic properties instead of complex entities such as the soil units assigned by the wrb particularly in providing spatial soil information displayed in digital soil maps any aggregation of this spatial soil information to soil units means a loss of information the soil landscape can be systematically described in its spatial continuum simply by the vertical order and extent of the wrb diagnostic horizons the diagnostic horizons are related in their thickness to a standard depth and listed from top to bottom in order of appearance typical diagnostic horizon thickness and occurrence probability were predicted from terrain parameters by classification and regression trees cart throughout the research area in southern ecuador the two disadvantages of cart abrupt prediction class boundaries and dependence on the dataset were addressed by hundredfold model runs on different data subsets leading to a range of possible predictions prediction uncertainty was included in the digital soil maps by calculating these predictions means and standard deviations as well as by horizon occurrence probability prediction model performance was evaluated by means of hundredfold external cross validation terrain parameters were found to have a strong influence on diagnostic topsoil properties however no influence on the vertical profile differentiation was observed hence predicting horizon thickness and subsoil diagnostic properties was difficult the systematic description of the soil continuum of this particular soil landscape resulted in histic and stagnic soil parts dominating the first 100 cm of the soil column for most of the area

predicting regolith properties using environmental correlation a comparison of spatially global and spatially local approaches abstract in this paper we assess the utility of mapping regolith properties as continuously varying fields using environmental correlation over large spatial areas the assessment is based on a comparison of results from spatially global and local analysis methods the two methods used are a feed forward back propagation neural network applied globally and moving window regression applied locally these methods are applied to five regolith properties from a field site at weipa queensland australia the properties considered are the proportions of oxides of aluminum iron silica and titanium present in samples as well as depth to the base of the bauxite layer these are inferred using a set of surface measurable features consisting of landsat data geomorphometric indices and distances from streams and swamps the moving window regression results show a much stronger relationship than do those from the spatially global neural networks the implication is that the scale of the analysis required for environmental correlation is of the order of hundreds of metres and that spatially global analyses may incur an automatic reduction in accuracy by not modelling geographically local relationships in this case this effect is up to 45 error at a tolerance near half of a standard deviation

development of an initiation criterion for debris flows based on local topographic properties and applicability assessment at a regional scale abstract damages caused by landslides have been increasing because of the greater frequency of localized heavy rain to prevent landslide disasters more efficiently more studies in relation to predicting the initiation areas of debris flows that cause large scale damage are necessary the main purpose of this study is to develop a criterion for detecting debris flow initiation areas by using an empirical method that was chosen from several types of approaches to debris flow initiation detection in this study ten gis based geomorphological datasets were obtained from slide and debris flow initiation areas located in seoul gyeonggi province and gangwon province the geomorphological characteristics of slide and debris flow occurrence areas were analyzed through a comparative analysis to identify relationships between debris flow initiation and each topographic index an initiation criterion for debris flows based on the geomorphological characteristics was suggested using an artificial neural network ann model combined with a modified threshold for the relationship between slope and upslope contributing area to validate the suitability of the initiation criterion for debris flow sequential applications of slope failure analysis and debris flow initiation analysis were conducted on a case study site to simulate the actual debris flow events as a result of the debris flow initiation analysis the prediction capture rate of the debris flow initiation criterion was determined to be 88 9 debris flow initiation areas totaling 143 300 m2 were identified among 1 935 400 m2 of slope failure areas predicted in the slope failure analysis it is efficient to apply the debris flow initiation criterion in the debris flow simulation because slope failure areas are only partly transformed into debris flows

patterns of basement structure and reactivation along the ne atlantic margin a lineament pattern on the ne atlantic margin is discussed illustrated by gravity and magnetic images in the norwegian sea and reviewed in the context of onshore field evidence while most possible fault trends exist three major sets predominate a ne sw left stepping lineament set defines the gross geometry of the margin while interposing northerly trends impose a rhomboidal geometry at a variety of scales the margin is segmented by nw se transfer zones sometimes involving significant offsets the principal trends are primarily a function of mesozoic cenozoic plate wide extensional stress fields certain proterozoic and caledonian lineaments were however opportunistically reactivated according to the extension direction caledonian ne sw orogen oblique shears typified by the more trondelag fault zone were reactivated via jurassic strike slip or oblique slip and were further exploited during cretaceous early cenozoic extensional episodes leading to continental break up jurassic e w extension may also have reactivated n s faults existing in the basement or generated in duplex systems between the ne sw shears precambrian and caledonian basement lineaments striking at a low angle to the extension direction probably predisposed the formation of major transfer zones

soil landscape modelling using fuzzy c means clustering of attribute data derived from a digital elevation model dem this study explores the use of fuzzy c means clustering of attribute data derived from a digital elevation model to represent transition zones in the soil landscape the conventional geographic model used for soil landscape description is not able to properly deal with these fuzzy c means clustering was applied to a hillslope within a small drainage basin in southern spain cluster validity evaluation was based on the coefficient of determination of regressing topsoil clay data on membership grades the resulting clusters occupied spatially contiguous areas we found a high degree of association with measured topsoil clay data r a 2 0 68 for three clusters and a weighting exponent of 2 1 location of the clusters coincided with observable terrain characteristics therefore we concluded that the coefficient of determination of regressing soil sample data on membership grades efficiently supports deciding upon the optimum fuzzy c partition the study confirms that fuzzy c means clustering of terrain attribute data enhances conventional soil landscape modelling as it allows representation of fuzziness inherent to soil landscape units

chemical diagenetic constraints on the timing of cataclasis in deformed sandstone along the pine mountain overthrust eastern kentucky abstract cathodoluminescence imaging reveals that sandstones of the middle pennsylvanian lee formation and breathitt group along the pine mountain overthrust pmo contain inter and intra granular authigenic quartz in proportions that differ markedly between samples of contrasting deformational state fracture surfaces generated during fault movement provided nucleation substrates favorable for the emplacement of substantial amounts of intragranular quartz up to 11 volume percent in the lee formation relatively undeformed sandstones contain cement that is dominantly intergranular whereas sandstones from highly deformed cataclasites along the trace of the pmo contain cement that is dominantly localized within intragranular fractures therefore the chemical diagenetic histories of different samples of breathitt and lee sandstones diverged markedly as a consequence of differing deformational histories and the cementation history thus constitutes a record that is relevant to deciphering the timing of deformation the small quantities of early formed intergranular cement within the cataclasites average 3 7 volume percent show evidence of breakage and accordingly must have largely pre dated the deformation quartz cementation modeling touchstone suggests that emplacement of this pre deformational intergranular cement within these deformed rocks can be bracketed within a period from approximately 280 to 260 ma an interpretation of fault movement that shortly post dates this initial period of quartz cementation is consistent with other estimates for the timing of the alleghanian orogeny because of their protracted period of burial rocks in the vicinity of the pmo remained at temperatures amenable to continued quartz cementation until the middle cenozoic and thus most of the quartz cementation in the cataclasites and also in the surrounding undeformed sandstones post dates movement on the fault

thrust related dome structures in the karibib district and the origin of orthogonal fabric domains in the south central zone of the pan african damara belt namibia abstract the high grade metamorphic south central zone scz exposes an oblique crustal section through the internal parts of the pan african damara belt in namibia the structural pattern of the south central zone is characterized by kilometer scale northeast trending dome structures for which a number of different origins have been proposed detailed structural mapping of the karibib and usakos domes in the karibib district indicates an origin of the two domes as large tip line folds located above blind thrusts the two domes are overridden from the southeast by a crystalline thrust sheet along the mon repos thrust zone and the thrusts and associated folds form part of a deeply eroded foreland northwest vergent fold and thrust belt intrusive relationships of syn and post tectonic granitoids constrain the timing of thrusting to between 550 and 540 ma corresponding to the main phase of collisional tectonics in the damara belt on a regional scale the south central zone is underlain by two orthogonal fabric domains northwest vergent tectonic transport documented in this study dominates the lower amphibolite facies northeastern parts of the south central zone in contrast a southwest directed orogen parallel extrusion is widely documented for the lower structural levels of the upper amphibolite to granulite facies southwestern parts of the south central zone that contain voluminous synkinematic granites and widespread migmatization fabric development in the two orthogonal domains can be shown to be contemporaneous and related to the main collision between the congo and kalahari cratons at ca 540 550 ma we suggest that the formation of the two orthogonal fabric domains represents the different crustal response of the rheologically layered crust to the late proterozoic crustal shortening at shallower crustal levels shortening of sufficiently strong crust in the karibib district resulted in vertical thickening and orogen normal folding and thrust transport shortening of the deeper levels of the scz resulted in pure shear deformation of the rheologically weakened and partially molten crust and the lateral orogen parallel displacement of rocks

an automated approach to the classification of the slope units using digital data abstract digital elevation and remote sensing data sets contain different yet complementary information related to geomorphological features digital elevation models dems represent the topography or land form whereas remote sensing data record the reflectance emittance or spectral characteristics of surfaces computer analysis of integrated digital data sets can be exploited for geomorphological classification using automated methods developed in the remote sensing community in the present study geomorphological classification in a moderate to high relief area dominated by slope processes in southwest yukon territory canada is performed with a combined set of geomorphometric and spectral variables in a linear discriminant analysis an automated method was developed to find the boundaries of geomorphological objects and to extract the objects as groups of aggregated pixels the geomorphological objects selected are slope units with the boundaries being breaks of slope on two dimensional downslope profiles each slope unit is described by variables summarizing the shape topographic and spectral characteristics of the aggregated group of pixels overall discrimination accuracy of 90 is achieved for the aggregated slope units in ten classes

the prediction of hillslope flow paths for distributed hydrological modelling using digital terrain models the accuracy of the predictions of distributed hydrological models must depend in part on the proper specification of flow pathways this paper examines some of the problems of deriving flow pathways from raster digital terrain data in the context of hydrological predictions using topmodel distributed moisture status is predicted in topmodel on the basis of spatial indices that depend on flow path definition the sensitivity of this index to flow path algorithm and grid size is examined for the case where the surface topography is a good indicator of local hydraulic gradients a strategy for the case where downslope subsurface flow pathways may deviate from those indicated by the surface topography is described with an example application

early depositional history of metalliferous sediments in the atlantis ii deep of the red sea evidence from rare earth element geochemistry the atlantis ii deep is a brine filled depression on the slowly spreading red sea rift axis it is by far the largest deposit of hydrothermally precipitated metals on the present ocean floor and the only known modern deposit that is analogous to laminated fe rich chemical sediments such as banded iron formation bif the brine pool at the bottom of the atlantis ii deep creates an environment where most of the hydrothermally sourced elements can be dispersed and deposited over an area of 60 km2 we analyzed the rare earth element concentrations in 100 small volume samples from 9 cores in different parts of the atlantis ii deep to better understand the origins of different types of metalliferous sediments detrital proximal hydrothermal and distal hydrothermal our results agree with earlier studies based on larger bulk samples that show the composition of the major depositional units is related to major changes in the location and intensity of hydrothermal activity and the amount of hydrothermal versus background sedimentation in this paper we address the origins of chemically distinct laminae down to sub millimeter that correspond to annual deposition ree patterns clearly reflect 3 different sources e g detrital scavenging direct hydrothermal input detrital ree that are delivered to the deep from outside account for most of the ree in the sediments of the atlantis ii deep similar to bif and are unaffected by fractionation due to hydrothermal processes during deposition and diagenesis fe and mn oxy hydroxides that form at the anoxic oxic boundary scavenge ree from the brine pool as they settle the fe oxy hydroxides contain a larger proportion of ree from seawater than any other sediment type and also scavenge ree from pore waters after deposition in contrast the mn oxy hydroxides dissolve before deposition and thus function as transporting agents between seawater and the brine however there is little evidence for direct seawater influence in the ree geochemistry of the sediments e g y ho ratio non ferrous sulfides form proximal to the hydrothermal vent source and inherit an hydrothermal ree pattern the total ree content of the presently forming fe oxy hydroxides is very low due to limited input of ree into the brine the largest proportion of non detrital ree appears to have been deposited early in the history of the basin from an initial brine pool that was relatively enriched in ree followed by a change in ree chemistry in later sediments similar abrupt changes in the ree chemistry of ancient chemical sediments may record similar processes including changes in local basin evolution and input of ree from different sources