base level buffers and buttresses a model for upstream versus downstream control on fluvial geometry and architecture within sequences abstract the effects of downstream base level control on fluvial architecture and geometry are well explored in several broadly similar sequence stratigraphic models cretaceous dakota group strata u s western interior have characteristics reflecting combined downstream and upstream base level controls that these models cannot address particularly three layers of amalgamated channel belt sandstone within this group thicken and are continuous for distances 300 km along dip that stretch the reasonable lengths for which these models are intended to apply as well architecture in up dip reaches records repeated valley scale cut and fill cycles this contrasts with equivalent strata down dip which record channel scale lateral migration with no such valley scale cycles apparent we here introduce the concept of buffers and buttresses to address these observations we assume that river longitudinal profiles are each anchored down dip to some physical barrier e g the sea strand etc that we refer to as a buttress buttress shift is considered the primary downstream control on base level profiles extrapolated up dip from the buttress over any modeled duration of buttress shift can range widely because of high frequency variability in upstream base level controls e g discharge etc all these potential profiles however are bounded above by the profile of highest possible aggradation and below by the profile of maximum possible incision these upper and lower profiles are buffers and they envelop the available fluvial preservation space thickness of the buffer zone is determined by variability in upstream controls and should increase up dip to the limit of downstream profile dominance dakota valley scale surfaces record repeated cut and fill cycles driven by up dip controls and are confined between thick stable buffers equivalent strata down dip record lateral reworking within a thinner channel scale buffer zone that was positioned by downstream controls regression exposed slopes similar to the buffer zone thus buffers were stable for long distances and durations this prompted dip extensive lateral reworking of strata into upstream valley scale and downstream channel scale sheets buffers and buttresses provide a broadly applicable model for fluvial preservation that captures upstream vs downstream base level controls on geometry and architecture the model lends general insights into dip oriented variations in fluvial architecture production of sheet vs lens geometry total preservation volumes for fluvial systems and variations in these factors related to contrasting climatic conditions and basin physiography the model can be amended to existing sequence stratigraphic approaches in order to capture dip oriented variations in sequence architecture

lower and lower middle pennsylvanian fluvial to estuarine deposition central appalachian basin effects of eustasy tectonics and climate interpretations of pennsylvanian sedimentation and peat accumulation commonly use examples from the appalachian basin because of the excellent outcrops and large reserve of coal 100 billion metric tons in the region particularly controversial is the origin of lower and lower middle pennsylvanian quartzose sandstones beach barrier marine bar tidal strait and fluvial models all have been applied to a series of sand bodies along the western outcrop margin of the basin interpretations of these sandstones and their inferred lateral relationships are critical for understanding the relative degree of eustatic tectonic and climatic controls on early pennsylvanian sedimentation cross sections utilizing 1000 subsurface records and detailed sedimentological analysis of the livingston conglomerate rockcastle sandstone corbin sandstone and pine creek sandstone an informal member of the breathitt group were used to show that each of the principal quartzose sandstones on the margin of the central appalachian basin contains both fluvial and marginal marine facies the four sandstones are fluvially dominated and are inferred to represent successive bed load trunk systems of the appalachian foreland base level rise and an associated decrease in extra basinal sediment at the end of each fluvial episode led to the development of local estuaries and marine reworking of the tops of the sand belts each of the sand belts is capped locally by a coal regardless of whether the upper surfaces of the sand belts are of fluvial or estuarine origin suggesting allocyclic controls on deposition peats were controlled by a tropical ever wet climate which also influenced sandstone composition through weathering of stored sands in slowly aggrading braidplains recurrent stacking of thick coarse grained fluvial deposits with extra basinal quartz pebbles dominance of bed load fluvial lowstand deposits over mixed load estuarine transgressive deposits thinning of sand belts around tectonic highs and along faults cratonward shift and amalgamation of successive sand belts on the margin of the basin and truncation of successive sand belts toward the fault bound margin of the basin are interpreted as regional responses to alleghenian tectonism inferred to have been the dominant control on accommodation space and sediment flux in the early pennsylvanian basin

role of neotectonics and climate in development of the holocene geomorphology and soils of the gangetic plains between the ramganga and rapti rivers abstract fifteen soil geomorphic units have been delineated from the gangetic plains between the ramganga and rapti rivers they were identified by remote sensing and field checks on the basis of degree of profile development their soils are grouped into five members qgh1 to qgh5 qgh5 being the oldest of a soil chrono association tentative ages assigned to qgh1 to qgh5 are 500 2500 8000 and 13 5000 yr b p respectively from the early holocene to about 6500 yr b p a cold arid to semi arid climate prevailed and pedogenic calcrete developed over large areas in the gangetic plains later a warm and humid climate and improved drainage resulted in complete removal of calcrete from soil profiles in some areas or its dissolution and re precipitation in lower horizons in other areas neotectonics seems to have played a significant role in the evolution of the geomorphology and soils of the area it determined areas of active sedimentation pedogenesis and erosion in upland regions it led to tilting and sagging of large blocks resulting in shifting and increase in sinuosity of the rivers tectonic slopes faults determined the courses of large rivers

late quaternary evolution of the la cantera fault system central precordillera argentina a morphotectonic and paleoseismic analysis abstract the la cantera fault system lcfs is the most active quaternary structure in the central precordillera of san juan in central western argentina the system extends for 47 km along the intermountain valley that separates the sierra de la cantera and la invernada north of the san juan river the average fault trend is 20 it dips at angles varying between 15 and 30 w in the northern section to approximately 40 w in the central section and up to 60 w in the southern section the fault affects holocene to recent alluvium deposits in the western piedmont of the sierra de la cantera and is defined by a series of landforms found in compressive tectonic environments including simple and compound counterslope fault scarps staircased alluvial terraces sag ponds flexural scarps aligned springs broom shaped drainage patterns river diversions beheaded channels changes in incision depths sinuosity and a river gradient along channels trench investigations indicated that at least three events occurred in the past 1 1 10 1 ky the topographic profiles of the selected channels and interfluves cutting across the northern and central trace of the fault were analyzed using a stonex vector gps differential system to establish the relationship between the topography and slope of the rivers this morphometric analysis of scarps indicates that active tectonics have played an essential role in controlling the drainage pattern in the piedmont leading the rivers to adjust to these slope variations based on the analyzed geomorphologic stratigraphic and structural characteristics the lcfs is considered to be a relevant seismogenic source in the intraplate portion of southern south america with a recurrence interval of at least 2000 500 years for moderate magnitude earthquakes during the last 11 000 years

channel enlargement by avulsion induced sediment starvation in the saskatchewan river can localized deposition resulting from river avulsion produce downstream sediment starvation effects similar to those in channels downstream from dams we explore this question by examining a 130 km reach of the saskatchewan river canada downstream of an active 500 km 2 avulsion belt initiated in the 1870s progradation history and measurements of bedload and channel bed grain size indicate that little coarse sediment has escaped the avulsion belt since its inception comparisons of 17 channel cross sections surveyed in 1911 1954 1956 and 2011 2012 show that bankfull areas enlarged by deepening and widening in the upper two thirds of the study reach since 1911 between 1911 and 1954 1956 average channel area increased by 35 in the upper 45 km and as much as 44 locally from 1954 1956 to 2011 2012 additional enlargement occurred in the upper 35 km averaging 52 since 1911 these increases occurred despite a 24 decrease in mean annual discharge since 1913 these changes are interpreted as effects of sediment sequestration in the upstream avulsion belt net erosion by sediment deficient outflows from areas of avulsive deposition may be an underappreciated process in evolving floodplains

evidence of quaternary tectonics along rio grande valley southern malargue fold and thrust belt mendoza argentina abstract the malargue fold and thrust belt is developed in the argentinian andes between 34 and 37 s through the tectonic inversion of upper triassic and lower jurassic depocenters of the neuquen basin with an uplift history since the cretaceous evidence of quaternary deformation has been described in the northern part of it 34 34 5 s potentially coeval to neotectonic activity along the eastern edge of san rafael block to the south compressional and extensional structures active during the quaternary were found in the dorso de los chihuidos along the agrio fold and thrust belt front 37 5 38 s contrastingly the southern segment of the malargue fold and thrust belt between these two areas with described neotectonic activity is partially covered by quaternary products of the payun matru volcanic field that may hide evidence of recent deformation in this 300 km gap of neotectonic information the landscape imprint of two individual structures aligned in the mountain front through the rio grande valley was analyzed new evidence of neotectonic deformation were recognized in particular over the western slope of the cara cura range expressed by faulting and folding of quaternary deposits and lava flows an 40ar 39ar age from a deformed lava flow at the flanks of an anticline in the foothills of the cara cura range may suggest at least an upper pleistocene compressional tectonic activity longitudinal river profile analysis revealed anomalies that show some correlation with the neotectonic structures described especially knickpoints and concavity index changes meanwhile normalized steepness index values showed a moderate response to recent deformation a proposed schematic geomorphic evolution for this segment of rio grande river is discussed to put the neotectonic activity into the context of landscape formation all together this evidence supports the idea of an active front through the rio grande valley during the quaternary coetaneous to an active broken foreland to the east in the southern central andes

submerged and buried pleistocene river channels in the gulf of trieste northern adriatic sea geomorphic stratigraphic and tectonic inferences abstract we use multibeam sonar scanning of the seafloor and high resolution sub bottom sonar profiling to investigate pre holocene geomorphic features in the gulf of trieste that are visible in seafloor topography we focus on two channel like features the paleori ana and paleoreka sub bottom profiles and published core log data reveal that these features represent the transgressive surface at the boundary between pleistocene continental and holocene marine sedimentation the geometry of the paleosurface the architecture and the acoustic facies of underlying sediment bodies clearly show that this surface represents an alluvial plain containing a moderate to low energy floodplain the paleori ana feature represents a meander belt with multiple meander scars and oxbow lakes while the paleoreka is a single slightly sinuous channel river with well developed levees geomorphic characteristics of the two rivers are replicated in the seafloor topography in astonishing detail despite being draped by up to 10 m of holocene marine sediments we extract paleoreka thalweg depths from sub bottom profiles to construct a longitudinal channel profile which runs approximately perpendicular to the main tectonic structures of the gulf we find no evidence of long term mm scale localized relative vertical tectonic movements which were previously inferred from repeated geodetic levelling surveys along the sw ne oriented slovenian coastline we speculate that the geodetic data may instead indicate short term interseismic deformation along the slovenian coast which would necessitate further investigation of tectonic activity and seismic hazard in the gulf area

active tectonics of ne gujarat india by morphometric and morphostructural studies of vatrak river basin abstract landscape owes its shape to the combination of tectonic and climatic forces differential displacement of land by tectonic processes changes the elevation of earth s surface locally and in turn affects the rate of geomorphic processes which are altitude dependent the tectonic and geomorphic processes are very tightly coupled and their results are intertwined to extract the tectonic signal the numerical modelling of the landscape of the vatrak river basin part of which falls in the northern part of the gujarat alluvial plains of western india has been undertaken applying morphometric and morphostructural approach the study helped in understanding the role of tectonic elements in the evolution of the basin demarcation of geomorphic indicators of active tectonics which include the analyses of asymmetry factor valley floor ratio gradient basin elongation ratio long profile and related parameters pseudo hypsometric integral drainage basin asymmetry drainage pattern analysis and azimuthal distribution of stream channels have been performed for each drainage network and associated basin the morphological field evidence of tectonics combined with the results of morphometric analysis has been used to obtain information about the orientation of tectonic elements and the possible reconstruction of their activity in recent times the analyses indicate eastward tilting of the drainage systems strong asymmetry in some reaches pronounced elongation of certain tributaries long profiles indicating base level lowering poor organisation of the hydrographic network and close alignment between lower order streams and active faults all these analyses point towards the active tectonism in the area data obtained through the statistical analysis of preferred stream orientations confirm that the old tectonic directions markedly influenced the drainage network development of the older order streams whereas streams of lower order which preferentially follow the n s and ne sw directions suggest that these tectonic trends were active until very recent times

on application of three dimensional interactive modeling in gravity and magnetics by h j gotze and bernd lahmeyer geophysics 53 1096 1108 august 1988 gotze and lahmeyer present the main principles and results new automatic system for the interactive modeling of three dimensional 3 d gravity and magnetic fields the high efficiency of the system is demonstrated convincingly on a practical example of a geologic study in the northwest german basin the importance and timeliness of this work are beyond doubt nonetheless a few remarks on the analytical results seem to be appropriate

depositional response to pliocene pleistocene foreland partitioning in northwest pakistan pliocene pleistocene synorogenic deposits of the upper siwalik group in the northwest pakistan foreland record changes in dispersal patterns provenance and sedimentary facies in response to himalayan contraction three depocenters in the northern pakistan foreland have been studied the peshawar and campbellpore basins situated north of the ranges associated with the main boundary fault and the soan syncline depocenter situated in the northern potwar plateau south of the main boundary fault in the peshawar basin an early generation of northward prograding alluvial fans and gravelly braided streams deposited at ca 3 0 ma was folded by en echelon pressure ridges bounded by high angle reverse faults between 1 7 and 1 4 ma the alluvial fan and fluvial deposits were entrenched and infilled by a second generation of northward flowing braidplain deposits in the campbellpore basin southwestward directed fluvial and alluvial fan deposition in response to uplift of the kawa ghar hills began at ca 1 8 ma in the soan syncline depocenter deposition occurred at ca 2 0 ma as southeastward flowing braided streams emanating from the khair i murat uplift and a southwestward flowing gravelly meandering river derived from highlands to the northeast previous stratigraphic and structural interpretations of this part of the himalayan foreland have included north dipping imbricated thrust faults and duplex structures to characterize the deformation patterns in the region recently acquired seismic and other geophysical and surficial structural data from the western part of the foreland indicate that the foreland has experienced strike slip as well as contractile deformation the structures that controlled depositional patterns of the upper siwalik group are localized uplifts bounded by high angle reverse faults and not regional thrust faults the pattern of pliocene pleistocene uplift and resultant deposition across the foreland does not indicate a progression of deformation in either the foreland or hinterland directions typical of fold and thrust belts

spatial patterns of late quaternary river incision along the northern tian shan foreland abstract river incision rate is widely used to track changes in tectonics or climate over time and space however the feasibility of utilizing the spatial variations of river incision to reconstruct past tectonic and climatic processes remains unclear here we focus on the spatial patterns of river incision along the northern chinese tian shan foreland three alluvial fans fp feh and flh are determined as the alluvial fan context of river incision and terrace classification providing the geomorphological framework across the foreland region four rivers i e the kuitun jingou manas and urumqi rivers from the western central and eastern part of the foreland are used to reconstruct the paleogeomorphology from the reference which is the best preserved terrace of each river system with ages clustering in different parts of the latest pleistocene early holocene the depth of incision constrained by the reference terrace of each river is obtained by comparing the present day topography and the reconstructed one the resulting profile of channel incision depth and rate of each analyzed river displays an overall decreasing downstream trend from the maximum where the river exits from the mountain range to zero such a trend has been attributed to the progressive lowering of the river gradient that was caused by the adjusted ratio of sediment input versus water discharge induced by climate change superimposing on the decreasing downstream trend an obvious step can also easily be observed onto the profile of channel incision of each river downstream of which channel incision is significantly less the step occurs near the thrust fault controlling growth of the outermost anticline through which each river cuts thereby implying the key role of local rock uplift in forming the river incision step the former observation implies that at the same timescale more river incision at the exit from the mountain range does not necessarily mean stronger climatic forcing of incision there we thus propose that in a foreland setting it should be the temporal pattern of river incision rather than its spatial variation that is helpful for unraveling the change in the forcing factor of downcutting

sedimentation in a tectonically partitioned nonmarine foreland basin the lower cretaceous kootenai formation southwestern montana the lower cretaceous kootenai formation in southwestern montana was deposited in the nonmarine cordilleran foreland basin in the united states during a period of intensified uplift in the westward adjacent but increasingly impingent sevier fold thrust belt concurrently the foreland basin was partitioned by uplift of intra foreland structural elements and incipient plutonism kootenai fluvial and fluviolacustrine depositional systems developed and evolved in response to changing basin architecture the kootenai thus provides a case study of nonmarine sedimentary responses to tectonic partitioning in a foreland basin the following criteria for recognition of tectonic partitioning of a nonmarine foreland basin are demonstrated by the kootenai 1 complex internalized drainage patterns which locally diverge from the over all regional paleoslope direction and a typical longitudinal pattern 2 intraformational and interformational unconformities both proximal to the fold thrust belt and within the foreland basin 3 evidence for cannibalization and redistribution of foreland basin sediments 4 abrupt deflections of paleodrainage axes in response to initiation of intraforeland uplifts and 5 dramatic base level alterations and consequent changes of fluvial geomorphology as a result of tectonic partitioning and segmentation of the foreland basin kootenai sedimentation can be divided into six phases 1 a tectonic pulse in the sevier fold thrust belt produced a thin but widespread sheet of gravel alluvium referred to as the basal conglomerate member which was deposited by a shallow perhaps ephemeral gravel bed braided stream system drainage was predominantly eastward across the axis of the foreland basin 2 subsequently initial activation of intra foreland structures over the present tobacco root madison gravelly and beartooth archean blocks and the boulder batholith caused reworking of the basal conglomerate in all but the westernmost foreland basin although the topographic manifestations of these uplifts were subtle the foreland basin was effectively partitioned into at least four distinct drainage basins the resulting deposit commonly called the pryor member but here referred to as the first sandstone member was deposited by sand and gravel dominant braided stream systems in the west and east respectively paleodrainage directions in the western foreland basin were southward but over all drainage was northward 3 a period of mud dominant sedimentation followed deposition of the first sandstone probably resulting from a combination of decreased tectonism influx of siliceous volcanic ash and change in source lithology 4 renewed tectonic activity in the fold thrust belt generated a second episode of coarse grained alluvial sedimentation producing the kootenai second sandstone member basin partitioning was accentuated but drainage directions remained essentially unchanged initial activation of the blacktail snowcrest uplift dammed the southern portion of the second sandstone fluvial system base level was elevated and a major anastomosed stream system developed upstream from the structural dam downstream from the axis of the uplift a transport efficient probably entrenched meandering system developed 5 the remainder of kootenai siliciclastic deposition was dominated by muddy fluvial and fluviolacustrine systems the foreland basin configuration remained essentially unchanged as drainage became ponded in response to further elevation of base level as basin partitioning continued an extensive carbonate lacustrine interval punctuated this period of sedimentation 6 gradual southward transgression of the cretaceous sea left a transitional fluviolacustrine to marine imprint on the sedimentary record of the uppermost kootenai and overlying blackleaf formation rejuvenation of orogenesis in the fold thrust belt augmented by cratonic and major intraforeland volcanic and sedimentary lithic sources renewed the supply of coarse grained detritus to the foreland basin during deposition of the blackleaf

identifying active structures in the chitwan dun central nepal using longitudinal river profiles and sl index analysis abstract previous studies have identified a seismic gap that has not witnessed any surface rupture earthquakes in the last 200 500 years located in the central sub himalaya i e area around chitwan intermontane valley a higher rate of convergence in these parts poses a great threat of a surface rupturing earthquake in future recent analysis of the 2015 gorkha earthquake to the north of this region suggests that it failed to rupture the surface moreover the stress is suggested to have transferred towards south therefore the chitwan intermontane valley located in the sub himalaya of the central himalayan seismic gap is investigated in this study to identify the active structures the longitudinal profile of a river considered to be one of the important geomorphic markers is used in this study for the identification of the active structures the hack profile and stream length gradient index sl index is used to identify the anomalous segments of the rivers these anomalous reaches are verified in the field for the presence of structures geomorphology of the region also supports the presence of active reverse faults in the valley abrupt break in the continuity of the geomorphic units and its correlation with the knick points and high sl index values indicate presence of around nine active structures in the chitwan intermontane valley six new structures viz jharahi thrust jht belani thrust bt west chitwan thrust wct danda thrust dt central churia thrust 2 cct 2 and shaktikhor thrust st have been identified in this study whereas three previously mapped structures viz main boundary thrust mbt barakot fault bkf and central churia thrust cct are also found to be active during the quaternary holocene most of the newly identified structures appear to be splays of either the mbt or the cct these structures have displaced quaternary landforms within the valley and are potentially active the structures can get re activated during large magnitude earthquake events in future

a chronostratigraphic framework for the upper jurassic morrison formation western u s a the attached document is the authors final accepted submitted version of the journal article you are advised to consult the publisher s version if you wish to cite from it

complex response of a midcontinent north america drainage system to late wisconsinan sedimentation abstract the geomorphic evolution of mud creek basin in eastern iowa u s a serves to illustrate how geomorphic influences such as sediment supply valley gradient climate and vegetation are recorded in the alluvial stratigraphic record sediment supply to the fluvial system increased significantly during the late wisconsinan through a combination of periglacial erosion and loess accumulation subsequent evolution of the holocene alluvial stratigraphic record reflects long term routing of the late wisconsinan sediment through the drainage basin in a series of cut and fill cycles whose timing was influenced by hydrologic response to change in climate and vegetation when viewed in a regional context the alluvial stratigraphic record appears to reflect a long term complex response of the flu ial system to increased sediment supply during the late wisconsinan hydrologic and sediment supply changes accompanying the spread of euroamerican agriculture to the basin in the 1800s dramatically upset trends in sedimentation and channel behavior established during the holocene

an outline of neotectonic structures and morphotectonics of the western and central pannonian basin abstract neotectonic deformation in the western and central part of the pannonian basin was investigated by means of surface and subsurface structural analyses and geomorphologic observations the applied methodology includes the study of outcrops industrial seismic profiles digital elevation models topographic maps and borehole data observations suggest that most of the neotectonic structures in the pannonian basin are related to the inverse reactivation of earlier faults formed mainly during the miocene syn and post rift phases typical structures are folds blind reverse faults and transpressional strike slip faults although normal or oblique normal faults are also present these structures significantly controlled the evolution of landforms and the drainage pattern by inducing surface upwarping and river deflections our analyses do not support the postulated tectonic origin of some landforms particularly that of the radial valley system in the western pannonian basin the most important neotectonic strike slip faults are trending to east northeast and have dextral to sinistral kinematics in the south western and central eastern part of the studied area respectively the suggested along strike change of kinematics within the same shear zones is in agreement with the fan shaped recent stress trajectories and with the present day motion of crustal blocks derived from gps data

insights into the tectonic topography of the present day landscape of the central iberian peninsula spain abstract the landscape of today s central iberian peninsula has been shaped by ongoing tectonic activity since the tertiary this landscape comprises a mountain ridge trending e w to nw se the central system separating two regions of smooth topography the basins of the rivers duero and tajo in this study we explore interrelationships between topography and tectonics in the central iberian peninsula regional landscape features were analysed using a digital elevation model dem slope gradients and slope orientations derived from the dem were combined to describe topographic surface roughness topography trend surfaces inferred from harmonic analysis were used to define regional topographic features low roughness emphasizes the smooth nature of the basins topography where surfaces of homogeneous slope gradient and orientation dominate high roughness was associated with abrupt changes in gradient and slope orientation such as those affecting crests valley bottoms and scarp edges present in the mountain chain and in some deep incised valleys in the basins one of the applications of roughness mapping was its capacity to isolate incised valley segments the area distribution of incised rivers shows their prevalence in the east on a regional scale the topographic surface can be described as a train of ne sw undulations or waves of 20 km wavelength these undulations undergo changes in direction and interruptions limited by n s trending breaks e w and ne sw troughs and ridges clearly mark structural uplifts and depressions within the central system these structures are transverse to the compressive nw se stress field that controlled the deformation of the central iberian peninsula from the neogene to the present they represent the upper crustal folding that accommodates alpine shortening n s breaks coincide with late miocene faults that control the basins sedimentation further associated palaeoseismic structures suggest the recent tectonic activity of n s faults in the eastern part of the tajo basin apatite fission track analysis data for this area suggest the occurrence of a significant uplift episode from 7 to 10 ma which induced the river incisions appearing in the roughness map n s and ne sw faults could be seismogenic sources for the current moderate to low seismic activity of the east tajo basin and southeast central system although n s fault activity has already been established we propose its significant contribution to shaping the landscape

tectonic footprints and landscape evaluation along kulur river valley kumaun lesser himalaya india abstract tectonic reactivation along the major boundary thrusts and subsidiary thrust faults in the himalaya during the quaternary period has resulted in the rejuvenation of the landforms considering the role of neotectonic activity in the hazardous kumaun region we aim to study the neotectonically formed landscape along the kulur river valley a non glacier fed tributary of the saryu river in the zone of the berinag thrust bt the field evidences encompassing a variety of geomorphic indicators e g unpaired fluvial terraces palaeo river channels alluvial fans active and stabilized landslides lineaments waterfalls alignment of springs deeply dissected hills straight meandering course of rivers streams v shaped valleys triangular fault facets and water logged river ponding along with integrated values of eight morphometric parameters and stream steepness index ks indices characterize the modification of landscape in the kulur river valley the computed morphometric parameters in the kulur river drainage and its tributaries show that the basin has been tilted and uplifted forming v shaped valleys along with deformed and disequilibrium longitudinal profile thereof suggesting it to be controlled by lithology and tectonics based on the response of active tectonics in form of geomorphic features and quantitative measurements of river channels the entire basin has been divided into three segments in which the northern and southern segments are active compared to the middle sector a possible nne ssw trending lineament fault running parallel to the kulur river has been observed in the upper catchment and is characterized by fluvial terraces river ponding and deflection and offsetting of drainage with rectangular pattern etc this may have given rise to the widening and straightening of river courses which provide the favorable room for river ponding resulting in deposition of about 2 m thick lacustrine mud deposit

lake patterns as related to neotectonics in subsiding basins the example of the ucamara depression peru abstract two northeast trending elongated lakes from the andean foredeep ucamara depression south maranon basin are analyzed in relation to basement structures neotectonic and scismotectonic data from the surrounding areas lake puinahua 25 60 km lies over pre cretaceous basement faults and lake punga 9 35 km which subsided in a historical times lies over a paleozoic basement uplift p axes from earthquake focal mechanisms located east and west of the ucamara depression are parallel to the lakes the trend of lineaments together will neotectonic data from the craton border suggest that lakes develop along extensional faults the western limit of the lakes are lie over folds from the front of the sub andean zone comparison of elongated lakes from the ucamara depression with other lakes from the andean foredeep suggests close relationships between lake pattern and geodynamics ria lakes are located along the front of the upper foothills and are possibly related to subsidence due to tectonic overloading of the sub andean border elongated lakes from the ucamara depression are situated in front of the wide low foothills of the sub andean thrust and fault belt subsidence is related to block faulting and tectonic overloading is weak these results are compared with previous studies of rectangular lakes from the beni basin which appear to be related to the bending of the craton border analysis of lake pattern is suggested as a complementary approach for the neotectonic study of active subsiding areas

depositional record of an avulsive fluvial system controlled by peat compaction neogene most basin czech republic this paper illustrates the response of a fluvial depositional system to the interplay between peat compaction and clastic sediment supply at a range of spatial and temporal scales as documented by extensive exposures in an open cast mine in the most basin part of the oligo miocene oh e rift eger graben basin system in the czech republic the most basin is characterized by the occurrence of a number of phenomena resulting from syn and post depositional interactions between clastic sedimentary systems and the underlying accumulation of organic material that was the precursor of the main lignite seam of up to 45 m thickness the studied strata are interpreted as deposits of an avulsive mixed load fluvial system the large scale depositional architecture documents an existence of at least five stratal packages up to 1500 m wide and up to several tens of metres thick representing a record of long term evolution of a clastic floodplain bordered by accumulating peat within each of the packages several small scale channel belts were documented individual packages are separated by carbonaceous mudstones indicating a period of reduced clastic input and interpreted as due to avulsion of the fluvial channels out of the floodplain limit two main mutually linked processes controlled the evolution of the studied fluvial system i syndepositional compaction of the underlying peat and ii avulsions of the channels away from the original floodplain resulting in formation of a new floodplain the processes which caused the channels of the hrabak fluvial system to reach the avulsion threshold were i decrease of rate of creation of accommodation leading to increased sinuosity and thus to a decreased channel slope and ii cross floodplain tilting of the channel belt caused by differential compaction of underlying organic rich substratum

late pleistocene evolution of the rhine meuse system in the southern north sea basin imprints of climate change sea level oscillation and glacio isostacy high resolution continuous core material geophysical measurements and hundreds of archived core descriptions enabled to identify 13 late pleistocene rhine meuse sedimentary units in the infill of the southern part of the north sea basin the netherlands northwestern europe this sediment record and a large set of optical stimulated luminescence dates 14c dates and biostratigraphical data allowed to establish detailed relationships between climate change sea level oscillation glaciation history and the sedimentary development of the rhine fluvial system during the last glacial cycle marine isotope stages 5e 2 eemian weichselian a well preserved eemian sediment record was encountered as the infill of a late saalian mis6 subglacial basin part of this record reflects groundwater rise controlled fine grained sedimentation as a result of postglacial early eemian sea level rise it shows strong analogy to developments known from the holocene rhine meuse delta outside of the glacial depressions near coastal deposits are only fragmentarily preserved the early glacial rhine sediment record is dominated by organic debris and peat layers marking landscape stability and low fluvial activity part of this record may have been formed under near coastal conditions significant amounts of reworked marine biomarkers in the lag deposits of early pleniglacial mis4 fluvial systems indicate that this period is characterized by extensive reworking of older mis5 near coastal sediments despite the marked early pleniglacial climatic cooling input of new sediment from the drainage basin was relatively low a feature that is related to the presence of regolith protective relic soil complexes in the basin during the early middle pleniglacial a major rhine avulsion indicates the system was in an aggrading mode and that sediment supply into the lower reaches of the rhine had strongly increased this increase in sediment supply coincided with the timing of major climate cooling that occurred from 50 to 45 ka onwards the increase in sediment supply is related to final breakup of the soil complexes in the drainage basin after 24 ka a strong input of coarse grained gravelly sediments was observed which indicates a strong increase in physical weathering processes and periglacial controlled supply of bedload sediment in the catchment a time delay between climate change 30 ka and channel belt aggradation 24 ka is explained as a result of transport path length between source and sink and or effects of higher continental runoff rates after 22 ka the late middle pleniglacial late pleniglacial and lateglacial rhine meuse record testifies for strong influence of glacio isostatic controlled differential upwarping of the study area glacio isostatic controlled forebulge upwarping and lateral valley tilting is shown to have deflected rhine meuse channel belts after 35 ka glacio isostatic upwarping is seen as the main cause for strong incision during the first phase of the late pleniglacial 30 24 ka at later stage glacio isostatic controlled incision was overruled due to high climate controlled sediment input from the catchment and probably initial glacio isostatic subsidence migration of channel belts towards the direction of the former centre of glacio isostatic uplift indicates that glacio isostacy influenced rhine meuse paleogeography until far into the lateglacial 2007 elsevier ltd all rights reserved

river braiding caused by rapid floodplain deformation insights from holocene dynamics of the jarama river in central spain abstract in this paper we will use an illustrative example to show the significance of rapid vertical movements inside floodplains as well as varying discharge values for the alteration of channel and sedimentation patterns during the holocene concerning such relationships well documented and well dated references from sedimentary records are rather rare the developments within the lower jarama valley have been significantly supported by an interaction of tectonic activity evaporite dissolution and halokinetics that initiated rapid vertical movements over short distances and caused the formation of knick points and gradient changes along the longitudinal floodplain profile furthermore the specific mediterranean climate caused highly variable discharges including extreme runoff peaks the juxtaposition of different floodplain gradients gave rise to spatial and temporal changes of discharge patterns and channel geometry which is reflected by varying sedimentation as well as erosion patterns we have been able to confirm that alluvial thickening due to intense dissolution and subsidence has been a characteristic and frequently recurring feature during the pleistocene moreover we want to emphasize that also during the holocene gradient adjustments exercised controlling influence on fluvial dynamics in particular with regard to channel response in fact we found consistency between low and moderate gradients and meandering single channel patterns associated with overbank deposition in distal floodplain positions only a section with stronger inclination revealed evidences for multiple channel discharge patterns in form of gravelly braided river deposits in comparison with recent discharge patterns and information from historical sources it appears that braided river deposition took place just within a short time frame between 5 and 3 ka cal bp this matches exactly a period of strong climatic aridity including highly variable precipitation and discharge patterns from that we conclude that in the first instance gradient changes promoted the change of channel and discharge patterns but however specific overlap of the parameters gradient and runoff is considered to have been necessary to generate braided discharge pattern a subsequent formation of braided patterns during the late holocene was presumably prevented by river entrenchment as well as a strong increase of sediment availability during the time of roman colonization on the basis of this study we can establish a number of general relationships between floodplain gradient runoff pattern and channel response during the holocene period that may help us to better understand fluvial behavior in various different areas

geomorphic evidence of unrecognized balapur fault segment in the southwest kashmir basin of northwest himalayas abstract the balapur fault bf is a high angle thrust fault reverse dipping 60 ne with an established length of 40 km striking nw se of the kashmir basin however geomorphic traces suggest that the strike of the bf propagates beyond what has been documented previously the present investigation aims to identify the unrecognized segment of the bf in the sw of the kashmir basin using hypsometric variability in longitudinal profiles knickpoints zones followed by validation through stream gradient index sl calculations of the rivers draining the area the longitudinal profiles of all the streams indicate prominent and consistent anomalies in the upper and mid reaches even on the coarse resolution data survey of india topographic maps 1 50 000 40 m dem srtm 90 m the profile anomalies in the upper reaches hard rock zone of the streams may be attributed to lithological contacts i e panjal trap agglomeratic slate shale limestone however the river profile convex segments and course deflection specifically in the mid reaches soft rock zone are most likely associated with recent tectonic activity geomorphic signatures suggest that these anomalies coincide with the strike of the recognized segment of the bf moreover the sl values of each stream express a clear agreement with the anomalies shown by the long profiles of the rivers hence we infer that the strike of the bf extends for a significant distance 95 km over the northeastern flank of the pir panjal range in the nw se direction

the origin and tectonic significance of asymmetrical meander belts in the hebgen lake area of sw montana the madison and south fork rivers occupy the northeast sides of their respective meander belts the form of the abandoned meander loops within these asymmetric meander belts indicates that they were produced by gradual northeast migration of the active channels this progressive migration can be related to tectonic tilting produced by regional extensional faulting at a high angle to the original channel belt axis which ran down a gently sloping outwash cone asymmetric channel sandstone bodies in the rock record can be recognized by the preferred dip of successive lateral accretion units in meander loops together with soft sediment deformation facies and thickness variations they may indicate tectonic deformation of the sedimentary surface

holocene environmental changes as recorded in sediments of a paleodelta southwest coast of india abstract sedimentary record of a 40 m deep borehole drilled in a paleodelta region of southwest coast of india has been studied for sedimentary proxies texture clay minerals geotechnical parameters and pollens the sedimentary record spanning from 12 ka to recent in age exhibits two different sedimentary environments of deposition sediments record high values of moisture content organic carbon and plasticity index sediment texture and geotechnical properties indicate a distinct change in depositional environment from marine to fluvial during the sea level fall i e after 7 ka it also suggests that major rise of sea level from 11 to 7 ka and regression from 7 ka to 5 ka contributed to the changes in the environment of deposition the downcore increase of illite and decrease of kaolinite at 12 m depth 6 ka and an upward increase of smectite and kaolinite and decrease of illite concentration support the major fall in sea level in the region that accounted for the change of depositional environment the pollen records reveal the abundant occurrence of semi evergreen type of mangroves during early to mid holocene thus the multi proxy record provides an evidence of change in the environment of deposition from marine to fluvial which might have been influenced by neotectonics sea level variations and monsoonal intensity in the region

changes in braided river morphology resulting from aggradation and degradation forty three experiments were completed in a large flume 1 8 x 18 3 m to examine the effects of sediment load sediment size and channel gradient on braided river morphology the laboratory results were supported by field research and analogs from the published literature subaerially exposed braid bars were formed by the dissection and further accretion of stalled linguoid dunes which are actively migrating bedforms bar forming processes and channel dynamics were the same in both sand and gravel bed channels however linguoid dunes stalled and were transformed into braid bars more frequently in gravel bed channels and therefore gravel bed channels were more intensely braided aggradation resulted in the development of more bars rather than in an increase in the size of preexisting braid bars the number of actively migrating linguoid dunes also increased with sediment load in the highly mobile sand bed channels conversely in degrading channels the number of braid bars decreased and average bar

sedimentology geochemistry and osl dating of the alluvial succession in the northern gujarat alluvial plain western india a record to evaluate the sensitivity of a semiarid fluvial system to the climatic and tectonic forcing since the late marine isotopic stage 3 abstract the alluvial successions in the northern gujarat alluvial plain western india have been investigated for reconstructing the climatic fluctuations during the last 40 ka alluvial architecture and geochemical proxies indicate prevalence of a strengthened indian summer monsoon ism with fluctuations between the late marine isotopic stage 3 mis 3 37 ka to the early mis 2 27 ka a gradual onset of aridity declining ism after 27 ka with peak aridity at 22 ka is observed a gradual strengthening of ism at around 18 and 12 ka followed by a short reversal in ism intensity between 12 and 11 ka is attributed to the younger dryas yd cooling event the aeolian sand sheet dated to 6 and 3 5 ka represents the onset of regional aridity following this a short lived humid phase was observed after 2 ka which includes the medieval warm period mwp the study suggests that the variability in the ism to the latitudinal migration of the inter tropical convergence zone was caused by insolation driven cooling and warming events in the north atlantic the incision of the valley fill alluvium occurred in two distinct phases the older incision phase occurred after 11 ka and before 6 ka whereas the younger incision phase that led to the development of present day topography is bracketed between 3 5 ka and before 1 ka the older incision phase is ascribed to the early to mid holocene enhanced ism climatically driven whereas the younger incision seems to be modulated by the activation of basement faults tectonically driven

upper mississippian lower carboniferous carbonate stratigraphy and syndepositional faulting reveal likely ouachita flexural forebulge effects eastern kentucky u s a abstract stratigraphic analysis of late middle to early late mississippian early carboniferous late meramecian early chesterian carbonates in east central and northeastern kentucky u s a shows six unconformity bound sequences the earliest late meramecian st louis sequence shows a relatively uniform distribution and a typical eastward appalachian gradient along the ene trending outcrop belt on the western margin of the appalachian basin however abrupt uplift and exposure of deeper water st louis deposits indicated by erosional thinning and well developed exposure features at the meramecian chesterian transition signal inception of regional early chesterian uplift that intensively altered the nature and distribution of the five overlying early chesterian carbonate sequences uplift was related to the syndepositional reactivation of wnw trending basement faults that broke up the st louis platform and generated a mosaic like distribution of the overlying five sequences due to structurally related erosional incision and paleoslope change to the southwest these early chesterian events coincide with a major phase of northeast directed ouachita orogeny on the southern margin of laurussia and concomitant forebulge migration to the ene modeling of regional stress distribution as well as timing and location during bulge migration strongly indicate that a migrating ouachita bulge reactivated basement structures and generated the noted stratigraphic anomalies in eastern kentucky and nearby areas the likelihood of low amplitude flexural waves like the ouachita bulge migrating across areas where they were not previously considered has major implications for understanding structural stratigraphic and eustatic anomalies in supposedly stable cratonic areas far removed from active tectonism

impact of the magnitude and frequency of debris flow events on the evolution of an alpine alluvial fan during the last two centuries responses to natural and anthropogenic controls the dynamics and the surface evolution of a post lgm debris flow dominated alluvial fan tartano alluvial fan which lies on the floor of an alpine valley valtellina northern italy have been investigated by means of an integrated study comprising geomorphological field work a sedimentological study photointerpretation quantitative geomorphology analysis of ancient to modern cartography and consultation of historical documents and records the fan catchment meteoclimatic geological and geomorphological characteristics result in fast rates of geomorphic reorganization of the fan surface 2 km2 the dynamics of the fan are determined by the alternation of low return period catastrophic alluvial events dominated by non cohesive debris flows triggered by extreme rainstorms which caused aggradation and steepening of the fan and avulsion of its main channel with periods of low to moderate streamflow discharge punctuated by low to intermediate magnitude flood events causing slower but steady topographic reworking the most ancient parts of the fan surface date back at least to the first half of the 19th century but most of the fan surface has been restructured after 1911 mainly during the debris flow dominated events of 1911 and 1987 phases of rapid fan toe incision and fan degradation have been recognized since the 1930s or 1940s the tartano fan has been subjected to a state of deep entrenchment and narrowing of the main trunk channel and distributary area post little ice age climate change and present day surface uplift rates have been considered as possible explanations for the observed geomorphic evolution but tectonic or climatic controls cannot account for the order of magnitude of the erosional pace anthropogenic controls plausibly override the natural ones in particular the building of a dam in the late 1920s about 2 km upstream of the fan seems to have triggered fan dissection having altered the sediment discharge through sediment retention copyright 2011 john wiley sons ltd

fluvial archives a valuable record of vertical crustal deformation abstract the study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms but also for identifying the nature of crustal deformation and its history in recent decades geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens here we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions the effects of horizontal deformation are not addressed channel long profiles have received considerable attention in the literature and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady state characteristics then we review the literature dealing with the transient response of rivers to tectonic perturbation through the production of knickpoints propagating through the drainage network inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories finally we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes as well as the erosional imprint of tectonic forcing sedimentary deposits such as fluvial terrace staircases are also considered as a classical component of tectonic geomorphology we show that these studies have recently benefited from rapid advances in dating techniques allowing more reliable reconstruction of incision histories and estimation of incision rates the combination of progress in the understanding of transient river profiles and larger more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace profile correlation i e extrapolation of local data to entire profiles finally planform changes in fluvial systems are considered at the channel scale in alluvial rivers and regional level in terms of drainage reorganisation examples are given of how numerical modelling can efficiently combine with topographic data to shed new light on the dis equilibrium state of drainage systems across regional drainage divides

analysis of srtm data as an aid to hydrocarbon exploration in a frontier area of the amazonas sedimentary basin northern brazil abstract the shuttle radar topography mission srtm provided an unprecedented source of space borne topographic information that has shown to be of particular interest for studies in densely vegetated tropical areas such as central amazonia the digital elevation models produced in that region show subtle details of the terrain that usually appear blurred in conventional remote sensing images interpretation of an srtm derived drainage network and geomorphometric features revealed several drainage anomalies which are possibly the surface expression of buried morphostructural features integration with geological and geophysical ancillary data strongly suggested that interpreted features constitute potential structural sites for hydrocarbon exploration however due to their inferred nature the structures herein identified are not by themselves a justification for drilling however they do provide information for planning seismic surveys thus reducing costs of the exploration campaigns as well as minimizing potential environmental impacts of such an enterprise in areas of tropical rain forests despite the relatively small size of the study area it is expected that procedures presented in this paper can be successfully applied throughout the approximately 1 000 000 km2 of sedimentary basins in the brazilian amazonian region

geomorphological analysis of the drainage system on the growing makran accretionary wedge abstract the morphology of six adjacent major catchments draining the onshore makran accretionary wedge in southeast iran and southwest pakistan was studied to examine how the channel pattern and the length profiles may reflect the recent and active growth of the wedge qualitative field surveys were combined with the quantitative analysis of channel steepness and concavity measured from digital elevation models these profiles were compared with modelled profiles using a stream power approach assuming homogeneously uplifting uniform rock substratum results show a distinct difference between the studied western and eastern catchments the three western rivers are in morphological equilibrium whereas the two eastern rivers exhibit profiles with prominent convexities and knickpoints thus notably diverging from equilibrium concave up shapes all the studied catchments share the same base level flow on similar lithologies and developed under uniform climate conditions therefore we interpret the morphometric differences in terms of differential rock uplift rate as a response to local tectonic activity this interpretation is consistent with both uplift rates of marine terraces along the coast of makran and the recorded seismicity the geomorphological analysis presented here extends coastal information to wide inland areas and documents longer term tectonic behaviour than the seismotectonic record hence the steeper surface slope and faster surface uplift rates recorded by the eastern catchments compared to equilibrium of the western catchments are regional long term signals relevant for a wide part of the makran accretionary wedge we attribute the regional geomorphic difference to quaternary variations in tectonic regimes that forced differential uplift rates of the wedge surface we hypothesize that the different tectonic regimes are related to different subduction rates

shifting of the kosi river northern india the kosi river shifts laterally over the himalaya foreland plain by continual minor cutoffs and bank cutting and by episodic major shifts across watersheds by moving into and then out of preexisting adjacent less actively aggrading streams migration is unidirectional because after a channel is filled to instability floodwater will drain preferentially into a new adjacent low rather than across it to the next watershed or back to the last abandoned channel major shifts seem stochastic and autocyclic they do not correlate with the many severe quakes and floods that undoubtedly helped prime the system for shifts

characteristics of direct human impacts on the rivers karun and dez in lowland south west iran and their interactions with earth surface movements abstract two of the primary external factors influencing the variability of major river systems over river reach scales are human activities and tectonics based on the rivers karun and dez in south west iran this paper presents an analysis of the geomorphological responses of these major rivers to ancient human modifications and tectonics direct human modifications can be distinguished by both modern constructions and ancient remnants of former constructions that can leave a subtle legacy in a suite of river characteristics for example the ruins of major dams are characterised by a legacy of channel widening to 100 s up to c 1000 m within upstream zones that can stretch to channel distances of many kilometres upstream of former dam sites whilst the legacy of major ancient anthropogenic river channel straightening can also be distinguished by very low channel sinuosities over long lengths of the river course tectonic movements in the region are mainly associated with young and emerging folds with nw se and n s trends and with a long structural lineament oriented e w these earth surface movements can be shown to interact with both modern and ancient human impacts over similar timescales with the types of modification and earth surface motion being distinguishable this paper examines the geomorphological evidence and outlines the processes involved in the evolution of these interactions through time the analysis shows how interactions between earth surface movements and major dams are slight especially after ancient dam collapse by contrast interactions between earth surface movements and major anthropogenic river channel straightening are shown to be a key factor in the persistence of long near straight river courses additionally it is suggested that artificial river development with very limited river channel lateral migration may promote incision across an active fold at unusually long distances from the fold core and may promote markedly increased sinuosity across a structural lineament

evidence of possible tectonic upwarping along the south carolina coastal plain from an examination of river morphology and elevation data although the fault s responsible for the 1886 charleston south carolina earthquake have not yet been identified primarily because of the lack of surface rupture evaluation of landsat imagery aerial photography and topographic maps have revealed an 200 km long 15 km wide north northeast trending zone composed of subtle topographic highs and morphologic changes in rivers that may be associated with tectonic activity river anomalies observed within this zone include river bends that are convex toward the north northeast incised channels changes in river patterns and convex upward longitudinal profiles analyses of geologic and geophysical data further indicate that these surface features may be the result of ongoing tectonic uplift along a north northeast trending fault zone possibly associated with recent seismicity near charleston

avulsion the relative roles of autogenic and allogenic processes abstract avulsion the abandonment of all or part of a channel belt in favor of a new course is controlled by both autogenic intrabasinal and allogenic extrabasinal processes however their relative roles are not known well the rhine meuse delta is without doubt the best studied delta regarding holocene avulsion processes based on studies of this delta an overview is given of 1 allogenic and autogenic processes influencing different aspects of avulsion 2 the relative importance of these processes in time and space and 3 observations that can be used to differentiate autogenic and allogenic causes of avulsion the following avulsion parameters are quantified and their allogenic and or autogenic nature are discussed period of activity of channel belts period between beginning and end of overbank sedimentation by the river channel interavulsion period time period between successive avulsions of a channel belt avulsion frequency number of avulsions per time interval in a given area and avulsion location in the rhine meuse delta the period of activity of the holocene channel belts varies considerably but shows no significant trend over time whereas extrabasinal factors climate base level and tectonics changed this suggests that this parameter is mainly autogenic controlled the average interavulsion period increased from 8000 cal yr bp to 2800 cal yr bp and decreased since then significant fluctuations occurred on a shorter time scale a maximum variability in the interavulsion period occurred between 3200 and 1800 cal yr bp this was a time when large channel belts gradually came into existence during this period the avulsion frequency also reached a maximum the long term increasing trend in interavulsion period is related to the decreasing rate of sea level rise the decreasing interavulsion period since 2800 cal yr bp can be explained by increased discharge and sedimentation resulting in an increase in the number of avulsions seven avulsion sequences as predicted by the mackey and bridge mackey s d bridge j s 1995 three dimensional model of alluvial stratigraphy theory and application journal of sedimentary research b65 1 pp 7 31 model may be recorded in the holocene dataset of the rhine meuse suggesting a periodicity of 500 600 yr each avulsion sequence coincides with a peak in the avulsion frequency the periodicity of 500 yr in the avulsion frequency is proposed to be autogenic however there is also a long term trend in the avulsion frequency that can be related to sea level rise and after 3000 14c yr bp to climate change and human influence avulsion locations are not randomly distributed over the delta and are related to the allogenic factors relative sea level rise local tectonics and changes in discharge and sediment load

tectono geomorphic indices of the erin basin ne kashmir valley india abstract the present study aims to assess the tectonic activity in the erin basin ne kashmir on the basis of several relevant geomorphic indices and field observations we use digital elevation model srtm and survey of india soi topographic maps in gis environment to compute the geomorphic indices the indices i e convex hypsometric curve high hypsometric integral value h i 0 5 low basin elongation ratio eb 0 17 low mountain front sinuosity values s mf 1 08 average low valley floor width ratios vf 4 suggest that the area is tectonically active moreover prominent irregularities knickpoints knickzones along longitudinal profile of the erin river even in homogenous resistant lithology panjal trap and anomalous stream gradient index sl values reflect that the erin basin is dissected by two faults ef 1 and ef 2 with nnw sse and ssw nne trends respectively the results of this preliminary study further substantiate the recent gps studies which argue that the maximum strain is accumulating in the ne part of the kashmir himalaya

braidplain sedimentation in a proterozoic rift basin the sao joao da chapada formation southeastern brazil abstract the sao joao da chapada formation 100 200 m thick is the basal unit of the middle proterozoic espinhaco supergroup this up to 3000 m thick and slightly metamorphosed sedimentary succession is exposed in the central part of the southern serra do espinhaco southeastern brazil detailed lithofacies studies were carried out to characterize the sedimentation and paleogeography of the sao joao da chapada formation six lithofacies are present horizontal to low angle cross stratified sandstones lithofacies sh sl trough cross stratified sandstones lithofacies st planar cross stratified sandstones lithofacies sp ripple cross laminated sandstones lithofacies sr massive to horizontally stratified conglomerates lithofacies gm and fine grained rocks lithofacies f these are usually arranged in fining and thinning upward successions characterizing waning flood cycles which are always bounded by erosional surfaces no complete cycles have been found however and the cycles are normally composed only of lithofacies sh sl and st the other lithofacies are rare the observed sedimentary structures and their arrangement the geometry of the bodies mainly sheet like to slightly lenticular the low relief morphology of the erosion surfaces bounding the waning flood cycles the coarse and poorly sorted texture of the sediments and the measured paleocurrent pattern unidirectional with little dispersion throughout the study area point to deposition on a wide ephemeral braidplain characterized throughout by relative uniformity of facies and paleocurrent directions water depths on this subsiding braidplain were maintained by high discharge streams debouching onto it from the upland catchment areas as these rivers spread onto the depositional plain the changes in gradient and substratum transformed them into channels of remarkable width and very large width depth ratios these rivers ran in braided tracts and floods were temporarily confined within banks in these tracts channel switching events associated with tilting and subsidence of the basin floor resulted in the accumulation of extensive sandstone sheets interfingering laterally with one another and succeeding one another vertically which built up a braidplain succession extending up to 35 km transverse to the paleoslope the sao joao da chapada braidplain flanked the west margin of a n s elongated rift basin

response of alluvial rivers to slow active tectonic movement alluvial rivers respond to valley slope deformation caused by active tectonics in various ways depending on the rate and amount of surficial deformation and on the type of river on the basis of experimental results and field examples hypothetical models of river response to anticlinal uplift and synclinal subsidence were developed for different types of alluvial rivers an experimental braided channel responded to anticlinal uplift across the channel with degradation and terrace formation in the central part of the uplift with subsidence aggradation in the central reach was the main response transverse bars developed downstream of the subsidence axis an experimental meandering channel responded to slope steepening with a sinuosity increase bank erosion and point bar growth occurred downstream of the anticlinal axis and upstream of the synclinal axis upstream of the uplift axis and downstream of the subsidence axis where the slope was flattened water flooded over bars local convexity in longitudinal profiles of the middle rio grande new mexico is considered to be formed by a domal uplift local aggradation and degradation could be explained by the effect of uplift the san joaquin river california which is now highly controlled does not show clear adjustment to the rapid subsidence due to ground water withdrawal it shows however a channel pattern adjustment to active tectonic subsidence that has been occurring for a long time the san antonio and guadalupe rivers in texas both increase their sinuosity significantly where monoclinal movements steepen valley slopes

thrust loads and foreland basin evolution cretaceous western united states two dimensional modeling of loading during the formation of the idaho wyoming thrust belt shows that regional isostatic compensation by flexure of an elastic lithosphere is sufficient to control the formation of a foreland basin the flexural rigidity of the lithosphere is inferred to have been approximately 1023 nm 1030 dyne cm on the basis of palinspastic comparison of predicted downwarping due to the thrust plate loads to the shape of the sedimentary wedge on the west side of the cretaceous western interior seaway erosion of part of the uplifted thrust plates redistributed the load depositing it farther to the east thereby causing subsidence over a much wider area than could have been accomplished only by the loading by thrust plates paleotopography after major cretaceous thrust events was calculated the resulting mountainous terrain gentle alluvial plain and flat sea floor correspond well with the topography of the modern foreland thrust belt and basin system in the andes of south america and to paleogeographic reconstructions in the western united states thrust belt topography is controlled by the subsurface geometry of the thrust faults particularly the positions of ramp zones and by isostatic subsidence

depositional history of lower cretaceous strata in northeastern new mexico implications for regional tectonics and depositional sequences lower cretaceous strata in northeastern new mexico reflect deposition during marine transgression and regression associated with the kiowa skull creek cycle development of regionally significant unconformities can be directly related to shoreline shifts during this cycle topography related to early cretaceous tectonic activity on crystalline basement structures including the dalhart basin tucumcari basin and the intervening bravo dome also had a direct effect on early cretaceous deposition and is reflected by thickness trends in marine strata the kiowa skull creek transgression was preceded by infilling of paleovalleys represented by the long canyon and campana sandstone beds of the glencairn formation and tucumcari shale respectively the long canyon and campana sandstone beds are equivalent to the plainview formation of central colorado and together they represent an extensive drainage network developed over a correlative unconformity that is preserved throughout most of the southern western interior glencairn and tucumcari marine shales represent clastic deposition during kiowa skull creek transgression and early regression base level drop associated with kiowa skull creek regression resulted in dramatic shoreline regression and deposition of fluvial channel sandstone in the dalhart basin which maintained a low offshore gradient this produced an erosional unconformity at the base of mesa rica channel sandstone that correlates with the well documented erosional surface at the base of the muddy sandstone in central colorado the tucumcari basin which maintained a steeper offshore gradient accumulated marine deltaic mesa rica sandstone at this time marine strata in both the tucumcari and dalhart basins thin toward the bravo dome mesa rica and upper tucumcari strata represent the only extensive marginal marine lowstand deposits found on the high plains to date associated with the southern arm of the kiowa skull creek sea major mesa rica deposition was followed by transgression that infilled only those mesa rica fluvial channels that were active at that time and also that deposited marine influenced strata of the basal pajarito formation this event most likely represents onset of the greenhorn cycle in northeastern new mexico other crystalline basement structures in the northern part of the united states western interior basin were active during early cretaceous time tectonism in these areas may be related to structures in northeastern new mexico and thus may be expressions of broad scale crustal strain in the early cretaceous western interior that is undocumented by present tectonic models

alluvial river response to neotectonic deformation in louisiana and mississippi repeat geodetic surveys show uplift of the monroe and wiggins anticlines in louisiana and mississippi there are deformed quaternary terraces which indicate long term deformation in the valleys of the alluvial rivers that cross these structures and there are floodplain and channel convexities that provide evidence of modern deformation in addition the channels show significant variations of morphology sinuosity gradient and depth and behavior appropriate to reaches of increased and decreased valley slope these alluvial rivers are adjusting to modern deformation and their adjustment confirms two geodetic leveling anomalies

fluvial perturbance in the western amazon basin regulation by long term sub andean tectonics haffer s refuge theory proposes that during the arid climatic phases of the late pleistocene tropical lowland forests of amazonia were reduced to isolated patches contributing to the high species richness of the present day forest the theory was developed because no obvious historic or modern geomorphic isolation barriers were recorded in amazonia analyses of radar images combined with stratigraphical data show that in the basinal forelands of the tectonically active andes the geological setting causes long term fluvial perturbance this leads to a temporally structured highly complex mosaic of fossil and present floodplains these dynamics have been present with varying activity and geographic range during the tertiary and quaternary providing site turnover that has not been recognized by the biogeographic tradition of the amazon basin

late quaternary sedimentation lower colorado river gulf coastal plain of texas investigations in the lower colorado river valley gulf coastal plain of texas have resulted in the development of a spatially and temporally controlled history of changes in channel and flood plain erosional and depositional processes when combined with paleoclimatic and stratigraphic data from the upper colorado river drainage and the record of glacio eustasy in the gulf of mexico this study permits evaluation of the relative influence of different external controls on channel and flood plain behavior the development of alluvial landforms and the development of alluvial stratigraphic sequences late pleistocene and holocene alluvial deposits of the lower colorado river have been subdivided into allostratigraphic units with chronological control afforded by radiocarbon ages in the bedrock confined valley up to 10 m of late pleistocene 20 000 14 000 yr b p sediments referred to as the eagle lake alloformation ela underlie a terrace at 17 20 m above the present day channel deposition of the ela was followed by bedrock valley incision then deposition of a complex holocene valley fill referred to as the columbus bend alloformation cba columbus bend allomembers 1 and 2 cba 1 and cba 2 underlie a terrace at 12 14 m above the present day channel cba 1 was deposited 12 000 5 000 yr b p whereas cba 2 was deposited 5 000 1 000 yr b p columbus bend allomember 3 cba 3 consists of channel and flood plain deposits that represent the past 600 yr of activity allostratigraphic units within the lower colorado valley correlate with allostratigraphic units in major valley axes of the upper colorado drainage and with records of climatic and environmental change suggesting that alluvial deposits record basinwide responses to climatically controlled changes in discharge regimes and sediment supply basal unconformities for holocene valley fills however appear to be 1 000 2 000 yr younger in the upper colorado drainage than they are in the lower colorado valley this time transgressioe episode of bedrock valley cutting was initiated by climatically controlled reductions in sediment supply but conditioned by limits on rates of up stream propagation of incision through a large drainage basin by contrast unconformities within holocene valley fills document time parallel episodes of flood plain abandonment and soil formation but little additional bedrock valley cutting and indicate decreased flood magnitudes following shifts to drier climatic conditions flood plain morphology and sedimentary facies changed through time in response to changes in climate coupled with a protracted degradation of upland soil mantles which altered the rate at which precipitation was transferred to stream channels as runoff during the late pleistocene through middle holocene runoff was filtered through deep upland soils floods were for the most part less flashy and contained within channel perimeters and flood plains were constructed by lateral migration without significant vertical accretion hence the ela and cba 1 contain few vertical accretion facies exposure of bedrock surfaces during the late holocene resulted in increased flood stages deep overbank flooding and construction of flood plains by vertical accretion hence cba 2 and cba 3 contain thick vertical accretion facies allostratigraphic units and bounding unconformities persist through the bedrock confined valley to the quaternary alluvial plain but stratigraphic architecture changes substantially in the downstream direction as a result of the last glacio eustatic cycle on the alluvial plain late holocene cba 2 and modern cba 3 deposited contemporaneously with the present interglacial highstand onlap and bury the ela and cba 1 which were emplaced during the last full glacial lowstand and the transgression that followed

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

submarine channel response to intrabasinal tectonics the influence of lateral tilt lateral tilting is a common deformation style in extensional basins its influence on subaerial channels is to a degree understood and may be significant controlling the style of channel development and the resultant sand body architecture growth faulting and lateral tilting in turbidite channel systems have been demonstrated from three dimensional seismic data but the resultant architecture of channels within these settings has not yet been documented in the carboniferous of northern england a sand rich slope channel developed within a basin undergoing late stage extension underwent progressive and unidirectional migration toward a topographic low on a laterally tilting block the resultant sandstone body is wedge shaped in cross section and composed dominantly of sigmoidal lateral accretion deposits the channel returned to an axial course before undergoing lateral migration in the same direction creating a multistory multilateral channel sandstone body the repeated unidirectional migration combined with evidence of syndepositional deformation suggests that active tectonism strongly influenced channel evolution and deposition a model of submarine channel evolution in extensional basins is presented in systems where large displacements occur the channel system may avulse creating isolated sand ribbons which are connected updip where the lateral dip is always more influential than the regional dip the system may pond in the hanging wall syncline the model is compared to a subsurface channel within the pliocene of the nile delta slope which was influenced by syndepositional fault movement application of the outcrop derived model allows some simple architectural interpretations to be made

use of radar data to unveil the paleolakes and the ancestral course of wadi el arish sinai peninsula egypt abstract aspects of the geomorphic evolution of wadi el arish the largest ephemeral drainage system in the sinai peninsula are still ambiguous and its paleochannels remain undefined one of the obstacles that impede recognition of these paleodrainage features is the variation in topography from past to present some of this variation is attributable to the post miocene tectonic activity in the region this activity might have continued to the present and led to developing an alternative course for the paleoriver the folded syrian arc belt in north sinai had a significant influence on the shape and direction of wadi el arish anticlinal ridges appear to have formed natural barriers that blocked the water flow across the main drainage course during humid periods and forced wadi el arish to deviate from its original course in this research we attempt to reconstruct the structural deformation and simulate the paleotopography to understand the evolution of the paleodrainage systems of the region the unique perspective offered by space borne radar data was used to define the structurally controlled paleolakes along wadi el arish and to trace its former course with a length of 109 km the former main channel course of wadi el arish was depicted west of gebel halal three major paleolakes were defined within structurally controlled depressions the largest lake occupied an area of at least 337 km 2 and contained approximately 10 7 km 3 of water when filled during pluvial phases the simulation of the paleotopography was confirmed by field observations and led to a concept for improved management of the renewable water resources in the study area thus a 2 km long canal with a depth of 6 m is recommended to be established within the structural uplift this canal would redirect the occasional runoff to a vast flat area west of gebel halal to provide water for approximately 1400 km 2 of fertile land for agricultural development the flow redirection would also help to mitigate the negative effects of flash floods in el arish city and maximize the harvesting of rain water that would otherwise be lost to the sea

tectonic origin and evolution of a transverse drainage the rio almanzora betic cordillera southeast spain abstract the rio almanzora forms one of the larger drainage systems within the betic cordillera southeast spain in its distal reaches prior to joining the mediterranean sea the rio almanzora cuts across a major topographic barrier the sierra almagro forming drainage that is transverse to the regional geological structure the long term drainage evolution of the rio almanzora and its creation as a transverse drainage across the sierra almagro has been examined by reconstruction of an evolving basin scale drainage network using a combination of the geological and geomorphological record the early stages of drainage evolution late miocene pliocene and plio pleistocene reveals the emergence of marine basins to the north and south of the sierra almagro and the development of unconnected drainage systems this emergence records the development of the proto rio almanzora on the south side of the sierra almagro as a prograding fan delta and alluvial fan system expansion of this drainage network via incision and headward erosion across the sierra almagro took place during the pleistocene during the early mid pleistocene the proto rio almanzora became fully transverse across the sierra almagro and linked the endorheic almanzora huercal overa basin with the vera basin a tectonically induced lowering of regional base level is proposed for the incision headward erosion and drainage network expansion that has resulted in the creation of the rio almanzora as a transverse drainage differential uplift between the huercal overa almanzora and vera basins has resulted in southwards tilting and the creation of a regional gradient the fluvial response to tilting was for incision into the steepened regional surface gradient via an increase in stream power the incision headward erosion and drainage network expansion by the proto rio almanzora and its creation as a transverse drainage appears to be part of a regional response by fluvial systems to differential uplift recorded throughout the betic cordillera of southeast spain during the plio pleistocene

tectonic and hydrologic controls on cyclic alluvial fan fluvial and lacustrine rift basin sedimentation jurassic lowermost cretaceous todos santos formation chiapas mexico abstract the nonmarine upper jurassic lowermost cretaceous todos santos formation of central chiapas mexico was deposited in half graben basins formed during the early rifting stage of the southern gulf of mexico basin this formation consists of alluvial fan fluvial and lacustrine sequences that were deposited under arid climatic conditions alluvial fans were built outwardly from the elongate basin margins by runoff that flowed transverse to the basin axis whereas fluvial units were deposited by rivers that flowed parallel to the basin axis lacustrine deposition took place in a topographic depression adjacent to the basin margin the presence of alluvial fan and fluvial or lacustrine deposits in vertically stacked cyclic megasequences hundreds of meters thick indicates that the basin opography changed through time this cyclicity denotes that periodically fluvial or lacustrine environments occupied the basin margin position and at other times alluvial fan sedimentation occurred there cyclicity was caused by periodic changes from high to low rates of basin subsidene the response of these three depositional environments to basin subsidence differed due to the unique hydrologic controls on sediment transport and deposition in each environment lakes were maintained by springs that emanated from the fractured fault margin and by fluvial discharge fluvial discharge and deposition resulted from precipitation or annual snowmelt anywhere in the river s expansive drainage basin whereas alluvial fan sedimentation occurred only when there was infrequent significant precipi ation in the small drainage basin from which fan sediment was derived as a result of these hydrologic controls the lacustrine or fluvial environments responded more quickly to periods of active tectonic subsidence and migrated over the fans to occupy the basin margin depression aided by a decrease in basin subsidence alluvial fans eventually prograded and displaced the fluvial or lacustrine environments away from the basin margin

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

fluvial sediments of the algeti river in southeastern georgia an archive of late quaternary landscape activity and stability in the transcaucasian region abstract in order to obtain information about landscape activity and stability during the late quaternary in the transcaucasian region fluvial sediments of the lower algeti river in se georgia were studied by means of geomorphologic sedimentologic and geochronologic methods these investigations show that sediments aggraded by the late pleistocene braided algeti river were strongly incised around the pleistocene holocene transition and subsequently a small scale pattern of diachronous fluvial terraces deposited by the now meandering river developed in the new valley during the holocene prior to ca 3 cal ka bp active phases of river channel aggradation and overbank sedimentation about 6 cal ka bp and 3 4 3 2 cal ka bp can be linked with climate driven vegetation changes i e stronger fluvial dynamics with sedimentation occurred during more arid and colder periods whereas the caucasian holocene climate optimum between 6 and 3 4 cal ka bp was characterized by stable geomorphologic conditions after 3 cal ka bp strongly increased human impact documented by former pollen studies is reflected by the fluvial dynamics as well i e an activity phase of strong overbank sedimentation 2 7 2 1 cal ka bp occurred during a period when forests in the lesser caucasus were burnt down two subsequent activity phases with fluvial sedimentation can be linked with historic events that probably both influenced vegetation distribution of the region i e a period of flourishing of georgia during the middle age and a time of large scale destruction of the country due to a persian invasion at the end of the 18th century ad respectively thus whereas no influence of tectonic events or fluctuations of the caspian sea level on the fluvial dynamics could be detected se georgia shows its fragile character with respect to climate and human driven vegetation changes similar to other semi arid landscapes of the mediterranean region

geomorphological markers of faulting and neotectonic activity along the western andean margin northern chile in the atacama desert northern chile some ephemeral channels are developed in the plio quaternary alluvial sequence that caps the neogene atacama gravels formation geomorpho logical studies and high resolution digital elevation data gps along a structural transect in the cen tral depression are used to document modern growth history of subtle folding and faulting in the fore arc region outcrop data of the most recent deposits are combined with observations of warped and faulted late quaternary pediments alluvial fans and terrace surfaces to propose unsuspected neotec tonic processes on the western flank of the domeyko cordillera neotectonic process recognition is here based largely upon the interpretation of alluvial landforms drainage organisation and evolution as the intermittent river network shows systematic patterns of course deflections successive incisions or deposition processes as it encounters the fault scarps or folds in the superficial deposits this area presents both n s trending active vertical faults in the topographically higher pampas and n s trending active folding in the lower pampas these faults seem to accommodate e w extension and compression that could be related to uplift of the western andean margin within a compressive context uplift may have taken place unevenly over the past few million years after the deposition of the superficial alluvial surfaces that cap the neogene atacama gravels copyright 2003 john wiley sons ltd

geomorphic characteristics of landscape development and formation of lakes in the zone of munsiari thrust garhwal himalaya uttarakhand india abstract the present investigation is focused on imprint of tectonic perturbation along a major tributary known as the lastar gad gad river in southeast catchment of the mandakini river in garhwal himalaya based on morphotectonic studies across the watershed we recognized evidences of neotectonics along the jutogh munsiari thrust mt mct ii various geomorphic features e g ponding of streams and formation of lakes fluvio lacustrine deposits waterfalls stabilized and active landslide fans dissected hills paired and unpaired terraces fault scarps and offsetting of drainage pattern etc point to the active tectonics the field investigations are supported by computation of morphometric indices such as low values of valley floor width to valley height vf asymmetry factor af elongated and tilted river basin with narrow valley floor as well as higher bifurcation ratio rb and sinuosity parameters immature topography and landscape elongation and tilting of drainage basin and accelerated erosion all show that the basin is structurally controlled the uplift along the valley is further manifested by two significant indexes e g stream length sl and steepness index ks also the mud deposits lacustrine flats and swampy and soggy land within the valley suggest the existence of an ancient lake basin named as gethina palaeolake downstream of present day badanital lake the 14c ams radiocarbon chronology of the badanital lake core as well as gethina jagtoli palaeolake profiles indicate the formation of these lakes around 5 6 ka bp due to tectonic upheaval along the mt we assume that a huge landslide activity blocked the course of a small stream badani gad forming an ancient lake at gethina locality followed by deposition of a landslide fan on which was created the badanital subsequently the palaeolake basin was filled with sediments due to accelerated erosion from almost vertical hills in the catchment owing to this the gethina ancient lake was disappeared and the modern badanital lake shrank to its present state

morphometry of drainage basins and stream networks as an indicator of active fold growth gorm anticline fars province iran abstract the zagros folded belt as one of the most tectonically active areas in the world contains nw se trending whaleback anticlines that are growing vertically and laterally morphometric indices are widely used in tectonic geomorphological research because of their low cost and relative ease of application drainage basins and their networks adapt to tectonically induced changes in surface slope and hence their qualitative and quantitative analysis can reveal aspects of active anticlinal growth this study evaluates the morphometric properties of drainage basins and their networks developed on the fold limbs using this quantitative data to detect lateral propagation of the gorm anticline in the zagros simply folded belt zsfb the gorm anticline was considered to be suitable for this approach because of the variability of drainage basins and their networks along the axis of the anticline and also transversely across its forelimb and backlimb the morphometric properties of stream networks including drainage density dd drainage frequency df ratio of 1st order streams to the total number of streams of all orders n1 n length of 1st order streams l1 spacing ratio r of main streams on flanks and drainage patterns were analyzed in three zones of the anticline southeastern se central and northwestern nw also the morphometric indices of drainage basins such as basin area ba shape bs asymmetry factor af hypsometric integral hi a new proposed crescentness index ci and sinuosity of anticline divide sad were evaluated results show that an increase in n1 n ratio and l1 from the center towards both the southeastern and northwestern fold noses suggests lateral growth of the anticline towards the southeast and northwest the se and nw zones are characterized by the smaller elongated and crescent shaped basins lower elevations lower dip slopes higher hypsometric integral and lower sinuosity of anticline ridge these results collectively suggest that the southeastern and northwestern fold noses are younger less eroded and laterally growing the formation of crescent shaped basins with asymmetric forked drainages developed in the se and nw zones are considered to be useful indicators of lateral growth of the gorm anticline although higher values of ba sad df and s indexes in the central part of the fold can be attributed to the older relative age of this area the activity of the nezamabad fault and the exposure of some weak rocks also play some roles in explaining the increase the values of parameters overall the n1 n l1 ci sad indexes as well as the fan shaped and asymmetric forked drainage pattern are the most useful tectonic geomorphological criteria to detect lateral propagation of anticlines

geomorphic and sedimentary response of rivers to tectonic deformation a brief review and critique of a tool for recognizing subtle epeirogenic deformation in modern and ancient settings abstract rivers are extremely sensitive to subtle changes in their grade caused by tectonic tilting as such recognition of tectonic tilting effects on rivers and their resultant sediments can be a useful tool for identifying the often cryptic warping associated with incipient and smaller scale epeirogenic deformation in both modern and ancient settings tectonic warping may result in either longitudinal parallel to floodplain orientation or lateral normal to floodplain orientation tilting of alluvial river profiles alluvial rivers may respond to deformation of longitudinal profile by 1 deflection around zones of uplift and into zones of subsidence 2 aggradation in backtilted and degradation in foretilted reaches 3 compensation of slope alteration by shifts in channel pattern 4 increase in frequency of overbank flooding for foretilted and decrease for backtilted reaches and 5 increased bedload grain size in foretilted reaches and decreased bedload grain size in backtilted reaches lateral tilting causes down tilt avulsion of streams where tilt rates are high and steady down tilt migration combing where tilt rates are lower each of the above effects may have profound impacts on lithofacies geometry and distribution that may potentially be preserved in the rock record fluvial sedimentary evidence for past tilting is traditionally based on the assumption that depositional features reminiscent of modern fluvial tectonic effects are evidence for past tectonic effects where it is closely associated with historically active structures or where non tectonic causes cannot be invoked however caution must be exercised when using these effects as criteria for past or current tectonic warping as these effects may be caused by non tectonic factors these non tectonic causes must be eliminated before tectonic interpretations are made

experimental test of tectonic controls on three dimensional alluvial facies architecture abstract in an extended series of papers by m leeder j r l allen j s bridge j alexander and others the depositional stacking patterns of channel belt deposits were related to tectonic and other external controls we refer to these models collectively as lab models these models established a basic connection between subsidence channel avulsion and the mesoscale channel belt architecture of an alluvial deposit two fundamental predictions resulted from this work 1 channel belt stacking density and hence connectedness is inversely correlated to temporal vertical changes in sedimentation rate and 2 channel belt stacking density and hence connectedness is directly correlated to lateral changes in sedimentation rate in this paper we make use of the experimental earthscape xes facility at the st anthony falls laboratory to examine the effects of temporally and laterally variable subsidence rates on mesoscale alluvial architecture we then compare the experimental results with the main predictions of the early lab models regarding the predictions of the lab models under conditions of high sediment supply and a highly active alluvial system lateral and downstream variation in subsidence geometry and rate have little effect on the details of alluvial architecture we found that the principal architectural signature of changes in subsidence geometry i e laterally variable subsidence rate is stratal tilting and that channel belts are not attracted to the subsidence maximum we hypothesize that the effect of variable subsidence geometry is felt by the fluvial system only if subsidence proceeds faster than the river can adjust to the formation of a topographic low via the deposition of overbank material in the form of splays and sheet sands our results lend impetus to the development of more complete three dimensional numerical models of mesoscale alluvial architecture that couple architecture to broader allogenic forcing mechanisms

depositional models for fluvial sediments in an intra arc basin an example from the upper cenozoic tokai group in japan abstract the upper cenozoic tokai group is an example of fluvial sedimentation in the japanese intra arc region the sedimentary basin in which the group was deposited consiss of several small basement blocks the depositional models and their controlling factors of the tokai group around the east coast of ise bay are clarified on the basis of facies analysis five sedimentary facies associations are recognized in the group they represent deposits from gravelly low sinuosity trunk streams gravelly to sandy low sinuosity streams sandy low to middle sinuosity streams sandy high sinuosity streams with a muddy flood plain and sandy tributary high sinuosity streams with an extensive flood plain spatial and termporal facies distributions within the stratigraphic framework of the group show depositioal processes with a resolution of 0 5 to 1 m y synthesizing tectonic movements and volcanism depositional models were mainly controlled by syndepositional movement of small basement blocks involving collapse subsidence and tilting in particular the change in tilt direction of a block resulted in high sinuosity streams instead of low to middle sinuosity streams fluvial sedimentation controlled by volcanism is also recognized in the group thus fluvial depositional models in this intra arc basin are controlled by the interaction of tectonism and volcanism

paleovalley related uranium deposits in australia and china a review of geological and exploration models and methods abstract the features and similarities in the geology of paleovalley related uranium mineralizing systems in australia and china can be used to refine strategies for exploration paleovalley related uranium resources include sandstone lignite and calcrete style deposits that are developed within the host sediments deposited in paleovalleys the paleovalleys incise either crystalline bedrock or older sedimentary rocks and uranium was deposited and concentrated by the influx of oxidized reduced groundwaters flowing in aquifers within the paleovalley fill the critical features of paleovalley related uranium deposits include sediment and uranium sources geological setting depositional environment age and relative timing of mineralization aquifer characteristics availability and distribution of reductants and preservation potential of the uranium mineral system this set of information provides a basis to establish the uranium mineralization model which can then be used to assist with generating targets for uranium exploration and prospectivity analysis of a region with respect to sino australian examples paleovalley related uranium deposits form mostly around the margins of sedimentary basins and the mineralization is commonly hosted within channel fills contained within paleovalleys developed upon or proximal to precambrian crystalline rocks that contain primary uranium sources the deposits that have been well studied show remarkably similar factors that controlled the formation of paleovalley related uranium deposits basement bedrocks with above background 2 8 ppm u levels of uranium 10 100 ppm that are linked to and or incised by paleovalleys are associated with these deposits and are the inferred source of the uranium in these regions extensive fluvial systems developed particularly during mesozoic and cenozoic times uranium from the bedrock was first dispersed into the sediments and then concentrated to form deposits through successive chemical remobilization precipitation and concentration the deposits formed in continental or marginal marine environments and commonly are associated with reduced lithologies containing pyrite and dispersed organic matter and or seams of lignite or show evidence of infiltrated hydrocarbons the mineralization is developed where oxidizing fluids carrying dissolved u reacted with reductants in the sediments geological geophysical and geochemical features of the paleovalleys and related uranium deposits are used to construct models to understand host sediment distribution fluid flow and ore genesis that can assist exploration for paleovalley hosted uranium deposits precise geometric definition of the basin margin and paleovalley architecture is important in identifying exploration targets and improving the effectiveness of drilling refinements in remote sensing geophysical and data processing techniques in combination with sedimentological and depositional interpretations provide an efficient approach for outlining the principal drainage patterns and channel dimensions to help reduce risk an exploration strategy should combine these technologies with a detailed understanding of the physicochemical parameters controlling uranium mobilization precipitation and preservation

late quaternary geomorphic scenario due to changing depositional regimes in the tangtse valley trans himalaya nw india abstract records from the tangtse valley in the trans himalaya reveal depositional history since 48 ka with fluvial aggradation followed by incision lacustrine sediment fill and later incision varied sedimentary architecture with fluvial episodes intervened by lacustrine pulses flood events colluvial and glacial activity are preserved the valley is located west of the pangong tso bangong co one of the largest lakes in tibet which has served as a spillway flooding and damming the entire tangtse valley resulting in the formation of a lake today pangong tso consists of five basins separated by shallow sills and is fed by snow melt documentation based on 14 c and osl chronologies of the sediment sections throughout the valley reveals evidence of a sixth basin of pangong tso toward west occupying the present day tangtse valley between 9 6 5 1 ka this event coincides with periods of high lake levels in tibet china as well as intensified monsoon periods over the indian subcontinent a fluvial regime around 48 ka and 30 21 ka with comparatively arid conditions and dry phases interspersed by flooding is documented the valley has been incised to depths of 40 50 m in the upper part and to 130 m in the lower part the incision rate ranges from 0 3 to 1 2 mm yr 1 in the upper part and reaches as high as 10 8 mm yr 1 in the lower valley much of the incision took place between 22 and 9 6 ka although repeated sediment fill incision cycles in the valley from 30 22 ka 22 9 6 ka 9 6 5 1 ka 5 1 ka and even to present time were observed

analysis of the evolution of ground movements in a low densely urban area by means of dinsar technique abstract this paper presents an application example of the use of the differential interferometry synthetic aperture radar technique dinsar for monitoring ground movements in a geologically complex area around the village of suria ebro basin catalonia ne spain associated to underground mining activities and to the presence of a salt dome the analysis has been mostly performed in a rural environment affected by ground movements with different patterns magnitudes and causes a total of fifty sar images recorded between 1995 and 2007 were processed to generate the interferograms in order to study the non linear trends or changes of the ground surface behavior the dinsar technique was applied in two sets of images the interferometric results in the form of vertical displacement rate maps were checked against conventional surveying and gps measurements the results present a significant discrepancy in some location due to the wrapping of the phase when both fast and significant deformations occur in order to avoid the latter effect and improve the accuracy of the results all sar images were reprocessed using topographic leveling and gps data of different monitored points to support the dinsar interpretation a detailed geological reconnaissance of the study area was carried out as well as an inventory of ground movement indicators four different patterns of ground movement have been identified active shifting subsidence associated to the progression of the mining exploitation fronts residual subsidence on abandoned galleries with a decreasing rate of closure uplifting due to the intrusion of the salt dome and sudden ground collapses sinkholes caused by the dissolution of soluble materials laying close to the ground surface

reconciling short recurrence intervals with minor deformation in the new madrid seismic zone at least three great earthquakes occurred in the new madrid seismic zone in 1811 and 1812 estimates of present day strain rates suggest that such events may have a repeat time of 1000 years or less paleoseismological data also indicate that earthquakes large enough to cause soil liquefaction have occurred several times in the past 5000 years however pervasive crustal deformation expected from such a high frequency of large earthquakes is not observed this suggests that the seismic zone is a young feature possibly as young as several tens of thousands of years old and no more than a few million years old

structural variation along the zagros and the nature of the dezful embayment structure varies along strike in the zagros fold and thrust belt of iran which is a principal element in the arabia eurasia continental collision pre collision late cretaceous ophiolite nappes kermanshah neyriz and related nappes of deep marine sediments radiolarite series were emplaced next to two regions pusht e kuh arc fars which later developed a consistent structural style across the range from the high zagros fault to the foreland limit of deformation the intervening area has a zone of highly imbricated arabian plate strata the bakhtyari culmination thrust southwest towards and over a low relief low elevation region the dezful embayment there are no ophiolite nappes northeast of the bakhtyari culmination isopachs reflect these different structural patterns from late cretaceous time but not earlier in late cretaceous time the dezful embayment recorded less deposition than adjacent areas to the northwest and southeast in the palaeogene there was little net difference between the dezful embayment and its margins the dezful embayment has been a depocentre since roughly 35 ma which is the likely time of initial collision between arabia and eurasia we propose that the syn collision structure and stratigraphy of the zagros is therefore strongly influenced by the variation in late cretaceous ophiolite emplacement but the original cause of this variation is not clear

high altitude plio quaternary fluvial deposits and their implication on the tilt of a horst western anatolia turkey abstract this study investigates the origin and regional tectonic implications of high altitude plio quaternary fluvial deposits developed over the bozdag horst which is an important structural element within the horst graben system of western anatolia turkey a total of 23 deposits occur near the modern drainage divide comprising fluvial to occasionally lacustrine deposits the deposits are all elongated in n s direction with a width length ratio of 1 10 the largest of them is of 13 km in length with a maximum observable thickness of about 100 110 m morphological lithological deformational characteristics of these deposits and the drainage system of the area all suggest that the deposits were formed due to uplift and southward tilting of the bozdag horst this tilting which is estimated as 1 2 to 2 2 caused accumulation of the stream load along channels flowing from south to north all the deposits were later dissected by the same streams with the exception of one deposit which still preserves its original lake form these deposits are of quaternary age which corresponds to the latest n s directed extensional tectonic phase in the region