testing the sensitivity of geomorphic indices in areas of low rate active folding eastern betic cordillera spain abstract active deformation structures have an incidence in topography that can be quantified by using geomorphic indices most of these indices have been checked in faulted regions with high deformation rates the application of several geomorphic indices hypsometric curve analysis normalized stream length gradient and valley width to valley height ratio to the drainage network of the southern limb of the sierra de las estancias antiform internal zones eastern betic cordillera where low rate active folding has been recognized allows us to investigate the suitability of these indices to identify active structures in such a scenario hypsometric curves clearly identify regions with recent uplift and young topography but they do not provide any constraint on the location of active folds local valley width to valley height index variations have been detected just coinciding whit the position of ene wsw active folds normalized stream length gradient index serves to locate active folds in areas of hard rock substratum but not in those areas with soft sediments neogene quaternary sedimentary basins this is most likely due to the fact that in the basins erosion is much more intense than in the hard rock sectors in view of these results we consider that geomorphic indices constitute a valuable tool for identifying sectors affected by low rate uplift related to active folding with the best results obtained in hard rock areas

plio quaternary uplift of the iberian chain central eastern spain from landscape evolution experiments and river profile modeling abstract the iberian chain central eastern spain is characterized by a dome shaped topography with poorly incised and relatively flat landscape in its interior at an elevation of 1300 m a recent regional tectonic event started during or after the late pliocene inducing deep valley incision on the flanks of the iberian chain the rate and timing of this deformation as well as the magnitude of the uplift induced erosion processes still lack a quantitative validation we used 3d signum and 1 d river profile numerical models to investigate the landscape evolution of the iberian chain from the late pliocene to the present and to study the response of topography and rivers to tectonically induced base level lowering our model results are supported by geological geomorphological and geochronological data the results of the signum experiments show that the iberian chain topography has experienced regional uplift since ca 3 ma with rates between 0 25 and 0 55 mm y 1 in response to this uplift rivers have incised at an average long term incision rate of about 0 22 mm y 1 and have progressively captured drainage areas from the chain interior to further validate the results of landscape evolution modeling we use a 1 d river incision model to explore the incision history of several rivers draining the iberian chain the results constrain the range of values of bedrock erodibility from 5 8 10 5 to 5 0 10 4 m 0 4 y 1 and predict long term incision rates similar to those from the signum experiments

numerical modeling of flow processes over gravelly surfaces using structured grids and a numerical porosity treatment this article describes the development and validation of a method for representing the complex surface topography of gravel bed rivers in high resolution three dimensional computational fluid dynamic models this is based on a regular structured grid and the application of a porosity modification to the mass conservation equation in which fully blocked cells are assigned a porosity of zero fully unblocked cells are assigned a porosity of one and partly blocked cells are assigned a porosity of between 0 and 1 according to the percentage of the cell volume that is blocked the model retains an equilibrium wall function and an rng type two equation turbulence model the model is combined with a 0 002 m resolution digital elevation model of a flume based water worked gravel bed surface acquired using two media digital photogrammetry and with surface elevations that are precise to 0 001 m the model is validated by comparison with velocity data measured using a three component acoustic doppler velocimeter adv model validation demonstrates a significantly improved level of agreement than in previous studies notably in relation to shear at the bed although the resolution of model predictions was significantly higher than the adv measurements making model assessment in the presence of strong shear especially difficult a series of simulations to assess model sensitivity to bed topographic and roughness representation were undertaken these demonstrated inherent limitations in the prediction of 3 d flow fields in gravel bed rivers without high resolution topographic representation they also showed that model predictions of downstream flux were more sensitive to topographic smoothing that to changes in the roughness parameterization reflecting the importance of both mass conservation i e blockage and momentum conservation effects at the grain and bed form scale model predictions allowed visualization of the structure of form flow interactions at high resolution in particular the most protruding bed particles exerted a critical control on the turbulent kinetic energy maxima typically observed at about 20 of the flow depth above the bed

kinematic model of active deformation in central asia the velocity field of present day deformation in central asia is modelled using a set of four rotating blocks siberia tarim tibet india on a spherical earth a best fit is inverted on the basis of estimated shortening rates across the main thrust zones himalayas tien shan and measured slip rates along the principal strike slip faults altyn tagh and karakorum separating those blocks the fit to the data implies that nearly all the present convergence between india and asia can be accounted for by slip partitioning on these four zones with as much as 50 absorbed by northeastwards extrusion of tibet this suggests that localised deformation governs the present mechanical behaviour of the central asian lithosphere

effects of a pebble cluster on the turbulent structure of a depth limited flow in a gravel bed river pebble clusters are important morphological features of gravel bed rivers and have a significant effect on the spatial and temporal response of the flow this paper presents original results from measurements of velocity taken at a high spatial and temporal resolution in a turbulent flow upstream and downstream from a pebble cluster three electromagnetic current meters 0 013 m in diameter mounted on a wading rod were deployed upstream and downstream of an isolated pebble cluster along 31 vertical profiles that contained between 7 and 13 points in a 5 m long section the high sampling resolutions in a natural environment permitted characterization of the complex dynamics of the turbulent flow in the vicinity of the cluster the description of these dynamics is based on the interpretation of contour maps of several turbulence statistics including moments of velocity distributions reynolds shear stress quadrant analysis and autocorrelation function downstream from the cluster flow is decelerated the intensity of turbulence increases and zones of strong vertical motions are present the superimposition of the maps allowed us to decompose the field of turbulent flow around a pebble cluster into distinct regions in a downstream direction from the cluster we observed zones of flow acceleration recirculation vortex shedding flow reattachment fluid upwelling and flow recovering results indicate the existence of highly dynamic boundaries between zones where strong intermittent events are generated they also highlight the difference between shedding and upwelling motions of the flow

differentiating geology and tectonics using a spatial autocorrelation technique for the hypsometric integral 1 hypsometry is thought to be sensitive to tectonic uplift rates and lithology differences in this study we calculated hypsometric integrals his using as topographic sources two digital elevation models of 10 and 90 m of pixel resolution in the granada basin se of spain the hi spatial distributions do not show clear spatial patterns and do not correlate with basin parameters as mean elevation or relief amplitude however when exploratory spatial data analysis is applied to the data distributions through local indices of spatial autocorrelation clear hot spots are visible that improve the geologic meaning of the hi the distributions are robust and independent of the model resolution but are scale influenced the application of this new method to the granada basin shows a strong correlation between the main distribution of active normal faults in the basin and the clusters of high or low hi values obtained in our analysis clusters with high hi values define the uplifted footwalls of these faults and regions uplifted in relation with rollover anticlines or where epeirogenic uplift has not been counteracted by local extension once the method was adjusted in the granada basin we tested its applicability in an area of known contractive tectonic activity central otago new zealand showing that the meaning of hi values is improved by using the autocorrelation techniques

mathematical modeling of graded river profiles numerical modeling of the longitudinal profiles of rivers at grade is accomplished using the basic equations of open channel flow sediment transport equations and empirical relations for downstream variation in flow discharge sediment discharge sediment caliber and channel width only in some cases are the computed stream profiles fit exactly by any one of the commonly supported mathematical function analogs to graded profile form exponential logarithmic or power function but in most cases any of these functions can provide a fit with a degree of error smaller than would be noted in treating field data profiles dominated by spatial change in fluid and sediment discharge are distinctly power functions while profiles dominated by sediment size reduction are not necessarily exponential in form other important controls on profile shape are the degree of downstream width change in response to increasing discharge and the general range of sediment size a dynamic model of a river s approach to grade

landscape response to tectonic and climatic forcing in the foredeep of the southern apennines italy insights from quaternary stratigraphy quantitative geomorphic analysis and denudation rate proxies we present new data about the morphological and stratigraphic evolution and the rates of fluvial denudation of the tavoliere di puglia plain a low relief landscape representing the northernmost sector of the pliocene pleistocene foredeep of the southern apennines the study area is located between the easternmost part of the southern apennine chain and the gargano promontory and it is characterized by several orders of terraced fluvial deposits disconformably overlying lower pleistocene marine clay and organized in a staircase geometry which recorded the emersion and the long term incision history of this sector since mid pleistocene times we used the spatial and altimetric distribution of several orders of middle to late pleistocene fluvial terraces in order to perform paleotopographic reconstruction and gis aided eroded volumes estimates then we estimated denudation rates on the basis of the terraces chronostratigraphy supported by published osl and aar dating middle to upper pleistocene denudation rates estimated by means of such an approach are slightly lower than 0 1 mm yr 1 in good agreement with short term data from direct and indirect evaluation of suspended sediment yield the analysis of longitudinal river profiles using the stream power erosion model provided additional information on the incision rates of the studied area middle to late quaternary uplift rates about 0 15 mm yr 1 calculated on the basis of the elevation above sea level of marine deposits outcropping in the easternmost sector of the study area are quite similar to the erosion rates average value thus suggesting a steady state fluvial incision the approach adopted in this work has demonstrated that erosion rates traditionally obtained by quantitative geomorphic analysis and ksn estimations can be successfully integrated to quantify rates of tectonic or geomorphological processes of a landscape approaching steady state equilibrium copyright 2014 john wiley sons ltd

geomorphic expression of active tectonics in a rapidly deforming forearc sila massif calabria southern italy we examine the tectonic geomorphology of la sila calabria southern italy a high standing 1500 m plateau surrounded by crustal extension with map dem and field data these data are used to constrain a simple geodynamic model that describes short wavelength deformation of the plateau rim topographic metrics including drainage patterns river longitudinal profiles and swath profiles are consistent with field stratigraphic relationships collectively suggesting that local tectonic deformation is embedded within a broader regional uplift that has increased the mean elevation of the sila plateau during the quaternary the concavity steepness and length gradient index of modeled river longitudinal profiles proved to be the most useful metrics for recording the effects of locally active faults a previously unrecognized horst on the northeastern portion of the plateau was identified with these data nevertheless the core of the sila plateau remains relatively undeformed with respect to its flanks which are characterized by steep fault bounded escarpments active extension has dropped base level for and unloaded the plateau rim causing deep fluvial incision and associated flexural uplift of the footwall this footwall uplift helps maintain a separate external and nearly radial drainage away from the plateau along its flanks and a nearly closed drainage for the plateau interior a drainage divide roughly correlates with the plateau rim inhibiting the process of drainage integration through the sila interior and subsequent landscape dissection as a result geomorphic processes driving erosion of the sila upland are lagging behind the tectonic processes that have driven rock uplift leading to an overall increase in mean surface elevation these results underscore the importance of the lag times a landscape may endure in transforming from one tectonic and base level condition to another we conclude that the calabrian forearc has a similar geomorphic evolution as the more northern apennines consistent with the emerging view that growth of apennine topography has been recent quaternary rapid and possibly decoupled from rock deformation in the orogenic wedge

river profiles along the himalayan arc as indicators of active tectonics abstract longitudinal profiles along sixteen major transverse himalayan rivers add important constraints to models of active continental subduction and its evolution these profiles are characterized by a zone of relatively high gradient that cannot be associated with differential resistence to erosion in all cases the base of the zone of increased gradients correlates with 1 the topographic front between the lesser and high himalayas 2 the narrow belt of intermediate magnitude thrust earthquakes 3 the main central thrust zone mct these features define a small circle in the central portion of the himalayan arc these correlations suggest that the discontinuity in the river profiles and the other features are controlled by a major tectonic boundary between the rising high himalayas and the lesser himalayas no sharp increases in gradient are observed near the main boundary thrust mbt except on a few rivers such as the jhelum or kundar where the mbt lies close to both the mct and the seismic belt thus it is unlikely that the mbt is a major tectonic boundary the diversion of river courses along the mbt and around anticlines in the sub himalayas has probably been caused by aggradation near the rosion deposition boundary upstream of uplifts in the mahabharat range and sub himalayas a parallel is drawn between the himalayas and new guinea based on the hypothesis that continent arc collision of the type occurring in northern australia preceded continent continent collision in the himalayas the present sedimentary tectonic phase in new guinea resembles the subathu paleocene eocene phase in the himalayas incipient counterparts of the major himalayan structures including the mct and the mbt are recognized in new guinea the drainage patterns in the himalayas and in new guinea bear a similar relation to major structures this suggests that 1 the tectonic evolution of the himalayas has been rather uniform since early stages of collision and 2 the himalayan drainage was also formed at these early stages and is therefore antecedent to the rise of the high himalayas

active tectonics in the sierra nevada betic cordillera se spain insights from geomorphic indexes and drainage pattern analysis article i nfo the sierra nevada of the central betic cordillera is a 3000 m high mountain range surrounded by neogene quaternary sedimentary basins having been uplifted since late miocene times the southern and western mountain fronts of the sierra nevada are fault bounded while the northern one is an unconformity between the neogene quaternary sediments of the guadix baza basin and the metamorphic rocks of the nevado filabride complex we have carried out a geomorphic study by examining drainage patterns and characteristics of mountain fronts in order to reveal areal variations and styles of rock uplift mountain front sinuosity smf area altitude relations hypsometric curves and valley floor entrenchment differ significantly between the northern western and southern mountain fronts the lack of important faults along the northern sierra nevada mountain front together with the elevated topographic position of the guadix baza basin average altitude is around 1100 m points to similar uplift of both geomorphic units sierra and basin in a single large scale crustal block the asymmetry factors show systematic asymmetries at both sides of the lanjaron river probably due to the presence of an active nne ssw oriented antiform in the western sierra nevada finally river profiles indicate maximal river entrenchment in the western part of the sierra nevada probably related to the uplift of the footwall of the padul niguelas fault system therefore our geomorphic analysis suggests that the western part of the sierra nevada is tectonically active by means of a combination of normal faults along the mountain front and nne ssw oriented active folds which in turn likely have a gravitational origin related to the exhumation of the footwall of the normal fault system

oblique convergence and slip partitioning in the nw himalaya implications from gps measurements we report gps measurements of crustal deformation across the kashmir himalaya we combined these results with the published results of gps measurements from the karakoram fault system and suggest that in the kashmir himalaya the motion between the southern tibet and india plate is oblique with respect to the structural trend we estimated this almost north south oblique motion to be 17 2 mm yr which is partitioned between dextral motion of 5 2 mm yr on the karakoram fault system and oblique motion of 13 6 1 mm yr with an azimuth of n198 e in the northwest southeast trending kashmir himalayan frontal arc thus the partitioning of the india southern tibet oblique motion is partial in the kashmir himalayan frontal arc however in the neighboring nepal himalaya there is no partitioning the entire india southern tibet motion of 19 20 mm yr is arc normal and is accommodated entirely in the himalayan frontal arc the convergence rate in the kashmir frontal himalaya is about 25 less than that in the nepal himalayan region however here the karakoram fault system accommodates about 20 of the southern tibet and indian plate convergence and marks the northern extent of the nw himalayan arc sliver the kaurik chango rift a north south oriented seismically active cross wedge transtensional fault appears to divide the sliver in two parts causing varying translatory motion on the karakoram fault on either side of the kaurik chango rift

has focused denudation sustained active thrusting at the himalayan topographic front the geomorphic character of major river drainages in the himalayan foothills of central nepal suggests the existence of a discrete west northwest trending break in rock uplift rates that does not correspond to previously mapped faults the 40 ar 39 ar thermochronologic data from detrital muscovites with provenance from both sides of the discontinuity indicate that this geomorphic break also corresponds to a major discontinuity in cooling ages samples to the south are proterozoic to paleozoic whereas those to the north are miocene and younger combined these observations virtually require recent pliocene holocene motion on a thrust sense shear zone in the central nepal himalaya 20 30 km south of the main central thrust field observations are consistent with motion on a broad shear zone subparallel to the fabric of the lesser himalayan lithotectonic sequence the results suggest that motion on thrusts in the toe of the himalayan wedge may be synchronous with deeper exhumation on more hinterland structures in central nepal we speculate that this continued exhumation in the hinterland may be related to intense sustained erosion driven by focused orographic precipitation at the foot of the high himalaya

quantitative analysis of relative tectonic activity in the sarvestan area central zagros iran neotectonics is a major factor controlling landform development in tectonically active regions and it has significantly affected fluvial systems and mountain front landscapes in the sarvestan area of the central zagros iran the area is located along the simply folded belt of the zagros and is an outcome of the sw ne oriented tectonic conversion that initiated in the late cretaceous and strengthened during the early miocene due to the collision of the arabian and eurasian plates to assess tectonic activities in the area we analyzed geomorphic indices the stream gradient index sl drainage basin asymmetry af hypsometric integral hi valley floor width valley height ratio vf drainage basin shape bs and mountain front sinuosity j these indices were combined to yield the relative active tectonics index iat using geographic information systems gis based on iat values the study area was divided into four parts class 1 very high relative tectonic activity 1 0 in area class 2 high 20 0 class 3 moderate 67 0 and class 4 low 12 0 the results are consistent with field observations on landforms and geology

shortening structural relief and drainage evolution in inverted rifts insights from the atlas mountains the eastern cordillera of colombia and the pyrenees the atlas eastern cordillera and pyrenees are thick skinned thrust fold belts formed by tectonic inversion of rift basins in continental settings a comparison of shortening between them shows a gradation from 20 25 in the central high atlas to 25 30 in the eastern cordillera and c 40 in the pyrenees accordingly there is a structural variation from interior zones with low structural relief and isolated basement massifs in the first two cases to an axial culmination of stacked basement thrust sheets in the pyrenees this results in marked topographic and drainage variation the high atlas and eastern cordillera contain axial plateaus dominated by structure controlled longitudinal rivers and orogen flanks with slope controlled transverse rivers whereas the pyrenees show a two sided wedge profile dominated by transverse rivers in spite of singularities exhibited by each orogen we propose that this spatial variation can be understood as reflecting different degrees of evolution in mountain building rapidly incising transverse rivers are capturing earlier longitudinal streams of the atlas and eastern cordillera thus reducing their axial plateaux which will eventually disappear into a transverse dominated drainage this pattern of landscape evolution may be characteristic of inversion orogens as they develop from initial stages of inversion to full accretion

magmatism and metamorphism in the ladakh himalayas the indus tsangpo suture zone abstract ladakh india provides a complete geological section through the northwestern part of the himalayas from kashmir to tibet within this section the magmatic metamorphic and geotectonic evolution of the northern himalayan orogeny has been studied using petrographic geochemical and isotope analytical techniques the beginning of the himalayan cycle was marked by large basaltic extrusions panjal trap of permian to lower triassic age at the northern margin of the gondwana continent indian shield these continental type tholeiitic basalts were followed by a more alkaline volcanism within the triassic to jurassic lamayuru unit of the gondwana continental margin lower jurassic to cretaceous oceanic crust and sediments ophiolitic melange s s accompany the triassic to cretaceous flysch deposits within the indus tsangpo suture zone the major structural divide between the indian shield high himalaya and the tibetan platform so far no relic of paleozoic oceanic crust has been found subduction of the tethyan oceanic crust during upper jurassic and cretaceous time produced an island arc represented by tholeiitic and calc alkaline volcanic rock series dras volcanics and related intrusives accompanied by volcaniclastic flysch deposits towards the tibetan continental margin subsequent to the subduction of oceanic crust large volumes of calc alkaline plutons trans himalayan or kangdese plutons intruded the tibetan continental margin over a distance of 2000 km and partly the dras island arc in the ladakh region the collision of the indian shield and tibetan platform started during the middle to upper eocene and caused large scale still active intracrustal thrusting as well as the piling up of the himalayan nappes the tectonically highest of these nappes is built up of oceanic crust and huge slices of peridotitic oceanic mantle spongtang klippe in the high himalayas the tectonic activity was accompanied and outlasted by a barrovian type metamorphism that affected triassic sediments of the kashmir nun kun synclinorium up to kyanite staurolite grade and the deeper seated units up to sillimanite grade cooling ages of micas are around 20 m y muscovite and 13 m y biotite towards the indus tsangpo suture zone metamorphism decreases with no obvious discontinuity through greenschist prehnite pumpellyite to zeolite grade remnants of possibly an eo himalayan blueschist metamorphism have been found within thrust zones accompanying ophiolitic melange in the suture zone

channel sediment variability along a river a case study of the siret river romania the siret river has the largest drainage basin 42 274 km2 in romania it gathers all the rivers from the eastern part of the eastern carpathians a fact that causes marked asymmetry of the basin this study is principally concerned with changes in the form of the longitudinal profile and the grain size variability introduced by the carpathian tributaries channel sediment analyses considered the petrography granulometry and morphometry of the pebbles relating these to the river bed and floodplain geometry and to some properties of the drainage basin the following conclusions arise the siret river undergoes an intense regrading of its longitudinal profile with marked aggradation between transects 24 and 26 see figures 1 and 2 this reflects selective accumulation of coarse material due to the massive contribution of the carpathian tributaries this phenomenon has been continuous throughout the holocene resulting in the gravel sheet formation of the pericarpathian piedmont

impact of tectonics on drainage network evolution of suru basin kargil n w himalaya jammu and kashmir india the main objective of this paper is to work out quantitative measurement of various geomorphic parameters as well as analysis of geomorphic landforms to study the tectonic character of suru basin morphometric analysis being widely used to assess the drainage characteristics of the river basins has also been found to be a useful tool to delineate tectonically active zones a number of parameters including the mountain front sinuosity asymmetry factor transverse topography symmetry hypsometry longitudinal profile and the shape parameters have been used the low mountain front sinuosity values 1 4 indicate that the tectonic forces dominate over erosive activity also the asymmetry factor 66 98 suggests that the right side of the basin has experienced uplift with the development of unpaired river terraces hypsometric integral 0 96 convex up hypsometric curve and the gps data of year 2011 2013 indicate that the relief of the basin is high relative to mean is in youthful stage and actively uplifting at the rate of 2 18 0 99 mm year the shape parameters further suggest that the suru river basin having lower elongation ratio is indicative of elongate shape of basin with tectonic forces outpacing the erosion power area altitude analysis of the suru river basin indicates that about 72 of the area of the basin is steeply to very steeply sloping and 28 area is moderately to gently sloping the area altitude indicates 72 area of basin could slide when there is slight shift in terms of tectonic disturbance in addition to the geomorphic indices the field investigations reveal tectonically unstable character exhibit a complex topography and varied quaternary sedimentation the major geomorphic landforms viz alluvial terraces alluvial fans debris cone scree and talus cone at the foothills are present throughout the valley with tectonic structures like micro folds back tilted beds deeply incised valleys faults and tectonic deposits ophiolites indicating that the tectonic activity has affected the basin the synergized results of geomorphometry field investigations and gps data indicate that the suru basin is tectonically active and uplifting

expression of active tectonics in erosional landscapes understanding the manner and degree to which topography in active mountain ranges reflects deformation of the earth s surface remains a first order goal of tectonic geomorphology a substantial body of research in the past decade demonstrates that incising channel systems play a central role in setting relationships among topographic relief differential rock uplift rate and climatically modulated erosional efficiency this review provides an introduction to the analysis and interpretation of channel profiles in erosional mountain ranges we show that existing data support theoretical expectations of positive monotonic relationships between channel steepness index a measure of channel gradient normalized for downstream increases in drainage area and erosion rate at equilibrium and that the transient response to perturbations away from equilibrium engenders specific spatial patterns in channel profiles that can be used to infer aspects of the forcing these aspects of channel behavior lay the foundation for a series of case studies that we use to illustrate how focused quantitative analysis of channel morphology can provide insight into the spatial and temporal dynamics of active deformation although the complexities of river response to climate lithology and uplift patterns mean that multiple interpretations of topographic data alone will always possible we show that application of stream profile analysis can be a powerful reconnaissance tool with which to interrogate the rates and patterns of deformation in active mountain belts

formation of melanges in the indus suture zone ladakh himalaya by successive subduction related collisional and post collisional processes during late mesozoic late tertiary time

effect of drainage area on hypsometry from an analysis of small scale drainage basins in the siwalik hills central nepal hypsometry of drainage basins area elevation analysis has generally been used to infer the stage of geomorphic development and to study the influence of varying forcing factors i e tectonics climate lithology on topography however the scale dependence of hypsometry has generally been neglected in order to assess the scale dependence of hypsometry this study focuses on the sensitivity of hypsometry to different digital elevation model dem resolutions and on the influence of drainage area hypsometry inferred from different dems is shown to be robust against variations of their resolution however hypsometry appears to be dependent on drainage area we propose that this scale dependence may reflect the varying importance of river and hillslope processes with basin area copyright 1999 john wiley sons ltd

analysis of drainage basin symmetry as a rapid technique to identify areas of possible quaternary tilt block tectonics an example from the mississippi embayment there is a coincidence of seismicity and major river valleys in the southwestern mississippi embayment that suggests control of the drainage pattern by northwest trending faults pleistocene river terraces reveal a strong southwestward preferred river migration in this region that may be a result of fault block tilting a rapid new technique of drainage basin analysis is herein presented that quantifies transverse topographic basin symmetry these data permit discrimination of random stream migrations and regionally preferred stream migrations and identify the direction of maximum migration if bedrock dip can be shown to be a negligible influence on stream migration then the direction of regionally preferred migration implies a period of ground tilting in that direction drainage basin asymmetry vectors bearing and degree of asymmetry calculated from transverse topographic profiles of 271 4 km basin segments in the study area suggest preferred stream migration in response to west southwest ward ground tilting bearing 259 the eastward regional dip of bed rock horizons only locally influences migration river terrace distributions reveal a chronology of stream migration episodes southwestward migration in the ouachita saline and arkansas river basins occurred during early to middle pleistocene time in the southwestern mississippi embayment a wisconsin early holocene southwestward migration episode is evidenced along southeast flowing reaches of the ouachita and arkansas rivers but not along the southeast flowing reach of the intervening saline river suggesting that these rivers overlie separate northwest trending tilt blocks although this technique does not provide direct evidence of ground tilting it provides a quick look method of identifying possible tilting elements in neotectonic regions using only topographic maps this technique is of greatest utility where active faults are concealed or poorly exposed such as in the mississippi embayment

seismic slip deficit in the kashmir himalaya from gps observations 1 gps measurements in kashmir himalaya reveal range normal convergence of 11 1 mm yr with dextral shear of 5 1 mm yr the transition from a fully locked 170 km wide decollement to the unrestrained descending indian plate occurs at 25 km depth over an 23 km wide transition zone the convergence rate is consistent with the lower bounds of geological estimates for the main frontal thrust riasi and balapora fault systems on which no surface slip has been reported in the past millennium of the 14 damaging kashmir earthquakes since 1123 none may have exceeded mw 7 6 therefore either a seismic moment deficit equivalent to a mw 8 7 earthquake exists or the historical earthquake magnitudes have been underestimated alternatively these earthquakes have occurred on reverse faults in the kashmir valley and the decollement has been recently inactive although this can reconcile the inferred and theoretical moment release it is quantitatively inconsistent with observed fault slip in kashmir

flow heterogeneity over 3d cluster microform laboratory and numerical investigation the present study examines the flow around a self occurring cluster bed form and the use of general computation fluid dynamics methods for hydraulic and geophysical flow applications this is accomplished through a comprehensive experimental numerical investigation in the laboratory cluster bed forms are first formed from movable sediment and laser doppler velocimeter measurements of two dimensional fluid velocity are then taken around a formed cluster a three dimensional 3d reynolds averaged navier stokes simulation of the physical cluster and flow conditions is then conducted using near wall shear stress transport sst turbulence modeling with the inclusion of hydraulic roughness ks r 31 150 ks h 0 1 ks 274 i e in the fully rough regime sst near wall modeling is advantageous compared to the more widely used wall functions approach for flows with significant roughness and flow separation because the model equations can be integrated down to the wall therefore sst near wall model

did the ebro basin connect to the mediterranean before the messinian salinity crisis the connection of the ebro basin via the ebro river to the mediterranean sea is supposed to have played a major role in the rejuvenation of relief of northern spain and especially of the south pyrenees from the neogene by lowering the initial base level of the ebro internal drainage area down to sea level however the timing and causes of this connection are still debated a fundamental issue is whether the ebro basin became connected to the mediterranean before or after the messinian salinity crisis morphological analysis and numerical modeling of landscape evolution show that this connection did not exist before the messinian salinity crisis but is effective from the pliocene because of progressive regressive erosion

a geomorphological approach to determining the neogene to recent tectonic deformation in the coastal cordillera of northern chile atacama the large 10000 km2 and local scale 300 m sedimentary succession was deposited east of the afs the succession fills previously deep paleovalleys and it consists of gravel so called atacama gravels which passes laterally into fine grained playa related deposits near the afs we interpret the deposition of this succession as a result of a blocking closure of the valley flowing from the precordillera due to the activity on afs a pedimentation episode followed sediment deposition and is locally strongly re incised by the main modern day river valleys draining the precordillera incision may result from either regional uplift of the forearc and or from more localized activity on the afs furthermore recent quaternary tectonic activity on the afs has been observed which is consistent with a localized relative uplift of the crustal block west of the afs

morphotectonic evidence from lateral propagation of an active frontal fold pakuashan anticline foothills of taiwan abstract the pakuashan anticline is uniquely suited for study of the forward and lateral growth of fault related folds the pakuashan ridge development arises from the late quaternary uplift of the most external thrust zone of the western foothills of taiwan from kaoshiung to taichung recent and active westward thrusting occurs at the front of the foothills the pakuashan anticline trending n 150 e in the northern part to n 000 in the southern part has been active throughout the quaternary period this activity is marked by geological structures tectonic geomorphology and seismicity a multisource and multiscale approach to study of the continental collision setting has been undertaken to combine tectonics sedimentology and geomorphology studies of fracture patterns allow identification of two main features of stress orientations a wnw ese compression direction and e w and n s extension directions quantitative geomorphic parameters have been used to define the morphotectonic evolution and to infer tectonic style along the mountain front geomorphic evidence provides significant information on the processes that govern lateral propagation of an active anticline quaternary terraces are uplifted tilted and folded over the pakuashan ridge drainage systems in areas of active compression give information on the thrust zone structures and their development steep drainage and high local relief indicate that the pakuashan anticline forms a well defined zone of high uplift especially in the southern part the two main controls on drainage in that area are rock strength in the hanging wall and propagation of the deformation towards the south

assessment of relative active tectonics southwest border of the sierra nevada southern spain abstract we present a new method for evaluating relative active tectonics based on geomorphic indices useful in evaluating morphology and topography indices used include stream length gradient index sl drainage basin asymmetry af hypsometric integral hi ratio of valley floor width to valley height vf index of drainage basin shape bs and index of mountain front sinuosity smf results from the analysis are accumulated and expressed as an index of relative active tectonics iat which we divide into four classes from relatively low to highest tectonic activity the study area along the southwest border of the sierra nevada in southern spain is an ideal location to test the concept of an index to predict relative tectonic activity on a basis of area rather than a single valley or mountain front the study area has variable rates of active tectonics resulting from the collision of africa with europe that has produced linear east west anticlinal forms as well as extension with variable vertical rates of normal faulting to about 0 5 m ky we test the hypothesis that areas of known relatively high rates of active tectonics are associated with indicatives values of iat

distribution of active rock uplift along the eastern margin of the tibetan plateau inferences from bedrock channel longitudinal profiles 1 current models of long term river incision into bedrock suggest that the local rate of differential rock uplift should exert a primary control on the gradient of channel longitudinal profiles however discrimination of this effect from the influence of variations in substrate erodibility sediment flux precipitation and transient changes in profile shape has proved difficult in practice here we investigate the controls on the spatial distribution of bedrock channel gradients adjacent to the sichuan basin in an effort to assess the degree and nature of active deformation along this margin of the tibetan plateau analysis of river longitudinal profiles utilizing a channel steepness index a measure of profile gradient normalized for drainage area reveals a zone of anomalously steep channels adjacent to the topographic front of the plateau margin channel profiles are systematically less steep in their headwater reaches on the plateau and in their lower reaches east of the plateau margin comparison of steepness indices to mapped lithologic variations reveals that lithology has only a limited influence on channel gradient in this field area we observe no systematic relationship between steepness indices and upstream drainage area channels of all size are steeper near the plateau margin we argue that these systematic changes are not readily explained as a consequence of increased sediment flux or of orographic precipitation we are led to conclude that steep channel profiles along the topographic front of the plateau reflect active differential rock uplift between this region and the foreland