impact of halite dissolution subsidence on quaternary fluvial terrace development case study of the huerva river ebro basin ne spain abstract this paper analyses the control of evaporite dissolution subsidence on the evolution of the lower 30 km long reach of the huerva river up to its confluence with the ebro river in the study area the huerva river flows across different interfingered lithofacies of the subhorizontally lying ebro basin fill 1 shales and sandstones upstream of cadrete 2 evaporites dominated by gypsum between cadrete and cuarte 3 gypsum with glauberite and halite units in the subsurface downstream of cuarte the halite shows a marked downvalley increase in thickness twelve terrace levels and seven pediment levels correlative to some of the terraces have been mapped in the studied area upstream of cadrete the terrace deposits with a relatively constant thickness less than 4 m and overlying unsoluble bedrock remain undeformed between cadrete and cuarte the deposits of some terraces show local thickening 60 m thick terrace alluvium that fills a 5 km long trough generated by synsedimentary subsidence phenomena caused primarily by the interstratal dissolution of halite the older terraces t1 to t4 show slight thickening 18 m and locally truncate paleocollapse structures ascribed to the interstratal karstification of halite beds the intermediate terraces t5 to t7 correspond to degradation surfaces that grade downstream of cuarte into aggradation flights underlain by the abruptly thickened deposits that fill this 5 km long dissolution trough subsidence migrated episodically downstream during the generation of these terraces and the subsidence aggradation rate was probably large enough to induce a base level drop and knickpoint migration upstream generating strath terraces with convergent longitudinal profiles the sedimentological changes that show the thickened terrace deposits in the subsidence area high proportion of overbank fines 60 including palustrine facies gravel channels with lower width depth ratio multiple fining upward cycles decrease in the calibre of the channel gravels indicate a change in the channel pattern from braided to meandering due to the lowering of the valley slope in the reach affected by subsidence some of the anomalous features of the lower terraces t8 to t12 attributable to dissolution subsidence include 1 steepening of the t8 terrace profile 2 change of the t10 terrace from degradational to aggradational downstream cuarte and 3 thickening recorded beneath the t11 terrace surface

earthquakes of the holocene geologic studies of earthquakes involve mapping of coseismic surface faulting and secondary deformation from historical events trenching and geomorphic analysis to define the timing and size of past earthquakes and investigations of fault zone structure and geometry in both unconsolidated sediments and bedrock this research is now being referred to as paleoseismology seismic geology and earthquake geology since the mid 1970s it has led to some of the most exciting and important contributions to the understanding of earthquake behavior in space and time hanks 1985 allen 1986 the present report is the first of what is hoped will become a regularly contributed summary of the geologic aspects of the study of earthquakes

long term fluvial archives in hungary response of the danube and tisza rivers to tectonic movements and climatic changes during the quaternary a review and new synthesis abstract the paper discusses the quaternary evolution of the danube and tisza rivers and their main tributaries in the context of evolution of the entire pannonian basin which is europe s largest intramontane basin within the alp carpathian orogen the palaeo drainage reconstruction of the pannonian basin for the pre quaternary period is outlined in connection with the gradual regression of lake pannon since the late miocene deltas of rivers that entered the basin from the northwest and northeast were gradually transformed into extended alluvial plains thus the earliest possible ancestor of the danube coming southeastwards from the alps could be as old as late miocene by the pliocene the whole lake pannon was infilled the former extensional basin formation was replaced by a compresional stress field which resulted in an uplift of the marginal flanks and late stage subsidence anomalies the increasing relief led to the formation of the quaternary drainage pattern the actively subsiding young basins were filled by fluvial sediments transported by the danube and tisza river systems from the uplifting mountains between the subsiding regions of the little and great plains the danube has formed an antecedent valley with terrace staircases between the uplifting sections of the transdanubian range and the north midmountains the formation of the terraces is attributed to periodic climate changes during the pleistocene combined with differences in the uplift rate the paper gives a complex overview of the classical chronology of the six terraces based on various data sources mostly dating of loess paleosol sequences travertines aeolian sand and tephra strata overlying the fluvial sediments complemented by scattered vertebrate faunal data and archaeological evidence directly from the terrace sediments the quaternary drainage pattern evolution of the great plain with a strong tectonic control is discussed in detail rivers originating from the uplifting marginal areas were drawn towards the subsiding depressions which served as local base level changes in subsidence rates in space and time throughout the quaternary resulted in the evolution of a complex drainage pattern a special emphasis is placed on the late pleistocene holocene development of the middle tisza region and the koros basin where the berettyo koros rivers form an eastern tributary system of the tisza river a comparative evaluation of these two areas is especially relevant as they provide insights into large scale late pleistocene avulsion of the tisza river osl dating complemented with inferred transport directions determined from heavy mineral analysis of fluvial sediments in the koros basin has revealed an ancient large meandering river system that can be identified with the palaeo tisza which was flowing along a tectonically controlled depression during the late pleniglacial successions in the middle tisza region have allowed differentiation between the older channels of the palaeo bodrog river and the sajo hernad alluvial fan and the younger meander belts of the new course of the tisza in the tisza system changes in river style braided to various scales of meandering show correspondence to millennial scale climate changes of the last 25 ka while in the koros basin the effects of tectonics are overprinted onto the regional climatic signals

magnitude and duration of surface uplift above the socorro magma body we use interferometric synthetic aperture radar and geomorphic data to constrain the magnitude and duration of uplift driven by the magma body beneath socorro new mexico united states interferometry spanning 1992 2006 confirms uplift of the socorro magma body at a rate of 2 5 mm yr however we find no clear evidence for volcanic uplift after an examination of three rivers rio salado rio puerco rio grande and two terraces llano de manzano llano de albuquerque crossing the socorro magma body our geomorphic measurements permit at most 25 50 m of cumulative surface uplift above the socorro magma body since the middle pleistocene but require no long term uplift given previously articulated thermal arguments for the socorro magma body we therefore suggest either a recent within the last few centuries initiation of uplift at socorro or that long term uplift and subsidence have been essentially equal

active deformation front delineated by drainage pattern analysis and vertical movement rates southwestern coastal plain of taiwan abstract orogenesis in taiwan results from an arc continent collision between the eurasian plate and the philippine sea plate the southwestern part of taiwan absorbs active shortening as evidenced by rapid crustal deformation and frequent earthquakes southwestern taiwan may be subdivided into three tectonic geomorphic domains including the plain pl the tilted tableland tt and the low hills lh based on geomorphology drainage pattern and stratigraphic records the pl domain is the westernmost and is characterized by meandering rivers with relatively low surface slope and river gradient but high river sinuosity the tt domain has slightly tilted terraces with river meanders and many tributaries are developed on its surface anomalous river sinuosity occurs as a result of active tectonics the lh domain has higher elevation and deformed geomorphic surfaces associated with a dissected landscape this domain also has high stream gradients with low sinuosity which may indicate active deformation we define crustal deformation using holocene deposits and radiocarbon dating in addition to geomorphic analysis that suggests a blind thrust may exist between the pl and tt domains this blind thrust may indicate the position of the active deformation front of the orogenic belt of southwest taiwan

late quaternary uplift and valley evolution in the northern apennines lamone catchment abstract the topographic evolution of mountain chains is fundamentally dictated by the balance of erosional and tectonic processes in the northern apennines several questions about the late holocene to present deformation style and uplift rates are still open we consider a typical ne facing drainage basin focusing on all the geomorphic markers capable of supplying direct or indirect information regarding tectonic forcing on the landscape characteristics of altitude and relief drainage pattern river profile and fluvial response expressions were found to be in good agreement indicating that the most recent tectonic activity consists of a general persistent uplift of the chain associated with an extensional regime where different sectors are distinguished through differential uplift such differences have been found to act both along and transverse to the chain causing similar coherent patterns of response in erosional processes the geomorphology of the catchment displays several features which together with the long sustained tectonic forcing indicate the near attainment of a dynamic equilibrium between the rates of tectonic forcing and erosional processes creating steady state topography

fluvial system response to tectonically induced base level change during the late quaternary the rio alias southeast spain abstract the rio alias of southeast spain crosses a major tectonically active structure the carboneras fault zone within the central portion of the drainage basin the fault originated in the mid miocene and has c 40 km of strike slip offset the impact of late quaternary movement along the fault zone on the evolution of the rio alias is addressed geomorphological and sedimentological analysis of the landform assemblage preserved suggests the development of highly sinuous meander loops and laterally incising streams during phases of tectonic activity continued tectonic activity led to the abandonment of the meander loops and a wave of incision that propagated c 2 km upstream the propagation of this incision wave was restricted by the development of a nickpoint itself controlled by an anticlinal structure sub parallel to the fault zone syn sedimentary and post depositional faulting is evident within the late quaternary fluvial sediments and suggests dominantly vertical movement along the fault lines with downthrow to the southeast regional climatic patterns of aggradation and incision resulting in a basinwide terrace sequence were complicated i e an additional terrace was created and meander wavelength was changed through the study reach by tectonic activity this study highlights the importance of tectonically modified sequences when interpreting climatically generated sequences of aggradation and incision

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

stream networks and long term surface uplift in the new madrid seismic zone stream networks are sensitive to low rates of surface uplift and can be used to decipher the history of large earthquakes even where faults do not rupture the surface as in intraplate seismic zones statistical analysis of alluvial network data from topographic maps in the new madrid seismic zone in the central united states shows that stream segment gradients deviate the most from an estimated natural stream profile where surface uplift is greatest evidence of cumulative deformation distilled from stream network patterns represents at least several meters of differential surface uplift during holocene time which suggests that more than one cycle of surface deformation occurred

drainage network geometry versus tectonics in the argentera massif french italian alps abstract the argentera massif french italian alps with its uniform lithology was selected to evaluate how known plio pleistocene tectonics have conditioned the drainage network geometry the drainage network was automatically derived and ordered from a 10 m resolution dem on hillshade images alignments of morphological features were identified the massif was subdivided into 22 domains of 50 km 2 within which the directions of every river channel segment and the direction of the aligned morphological features were compared and contrasted with the strike of tectonic structures measured in the field results suggest that the argentera drainage system is variously controlled by recent tectonics depending on the massif sector taken into account in the nw sector the vertical uplift is less because the strain has been accommodated in an oblique direction along a lateral thrust in the se sector strain in a predominantly vertical direction along a frontal thrust has resulted in a major vertical displacement accordingly the nw sector is characterized by i a strong geometric relationship between the main tectonic structures and the directions of river channels ii longitudinal main rivers bordering the massif and iii a general trellis pattern within the domains in the se sector the prolonged uplift has forced an original longitudinal drainage system to develop as a transverse system this change has occurred by means of fluvial captures that have been identified by the presence of windgaps fluvial elbows and knickpoints at the domain scale intense uplift of the se sector has prompted the drainage pattern to evolve as a dendritic type with no clear influence of structure in the channel orientations

physical and chemical signatures of a developing anticyclonic eddy in the leeuwin current eastern indian ocean a multidisciplinary cruise aboard the r v southern surveyor was conducted in may 2006 to sample a developing anticyclonic eddy of the leeuwin current off western australia the eddy formed from a meander of the leeuwin current in mid april 2006 and remained attached to the current until mid august in this study a combination of satellite data altimeter sea surface temperature and chlorophyll a and shipboard measurements acoustic doppler current profiler and conductivity temperature depth were used to characterize the physical and chemical signatures of the eddy the temperature salinity properties of the mixed layer waters within the anticyclonic eddy and on the shelf were both connected to that of the leeuwin current indicating the water mass in the eddy is mainly derived from the leeuwin current and the modified leeuwin current water on the shelf above the salinity maximum near the eddy center there was a regionally significant concentration of nitrate 0 9 mol l 1 and the maximum 2 mol l 1 was at 150 in depth below the photic zone nitrification within the eddy and or local upwelling due to the forming eddy could be responsible for this high concentration of nitrate near the eddy center which potentially makes the eddy a relatively productive feature in the leeuwin current

emergence of subaqueous depositional environments in advance of a major ignimbrite eruption capel curig volcanic formation ordovician north wales an example of regional volcanotectonic uplift abstract the garth tuff of the ordovician capel curig volcanic formation comprises a laterally extensive sheet of largely welded rhyolitic ash flow tuff that can be traced from a proximal subaerial to a distal marine environment six facies associations are recognized within subjacent sedimentary successions facies are interpreted as deposits of stream dominated alluvial fans ephemeral streams braidplain lower delta plain delta front and shallow marine environments the development of a large scale coarsening and or shallowing upward sequence reflects the amount of differential tectonic uplift between fault bound highlands and depositional basin there is no evidence for volcanicity associated with sedimentation uplift resulted in aggradation and progradation of fan and braidplain deltas a basinward shift in the loci of dominant sedimentation and a 15 km advance in the position of the pre eruption coastline associated tilting of fault blocks influenced the position of fluvial systems on braidplain with channel belts localizing along one margin in the area of greatest subsidence the spatial correlation between pre emplacement geography and location of probable vent for garth tuff implicates upward and or lateral migration of the magma as the most likely mechanism driving these tectonic changes

late holocene tectonic influence on hydrology and vegetation patterns in a northern amazonian megafan abstract the factors that control the heterogeneous canopy of the amazonian rainforest have long been a topic of interest for research among all hypotheses changes in landscape due to geological processes have been increasingly defended large areas of open vegetation in the northern amazonian lowlands are confined to paleolandforms created by the abandoning of megafan depositional systems previous investigations related the megafan sedimentation in this region to late pleistocene holocene tectonic reactivations however the influence of neotectonics on both the amazonian megafans and associated vegetation cover remains to be further investigated we studied a depression preliminarily noticed in the south central sector of one amazonian megafan i e virua megafan aiming to determine if its genesis was due to recent tectonic subsidence after the megafan abandoning the investigation combined morphostructural hydrological and remote sensing reflectance analyses as well as characterization of floristic communities in the modern and ancient environments based respectively on field inventories and palynological data the results indicated a nearly 10 km long and rectangular shaped area having straight margins paralleling nne ssw trending regional structural lineaments hydrological analysis suggests that this area experiences the largest floods during wet seasons a condition compatible with the topographic data that revealed a smoother gradient of 3 m comparing this area with others from the megafan plain in the studied depression numerous forest patches are arranged as sets of parallel straight lines trending consistently in the ne sw direction the patches have spectral values that differ significantly from other forest patches over the megafan surface being compared to those of seazonally flooded forests such as igapos and varzeas that surround the megafan paleolandform in addition a forest patch within the depression revealed trees physiologically adapted to tolerate submersion 6 to 7 months per year which is also a characteristic of the inundated forests external to the megafan these data altogether led us to conclude that the studied depression consists of a shallow subsiding basin formed by tectonic reactivations in the mid late holocene tectonic instability at around 2 cal kyr bp further disturbed this system by creating ne sw trending lakes and leading to the replacement of seazonally flooded forests by grasslands thus tectonic activity in a relatively recent geological time must be accounted when analyzing plant distribution in the amazonian wetlands

climatic and tectonic controls on fluvial incision and aggradation in the spanish pyrenees the influences of tectonic and climatic changes on upland river systems are investigated using data from plio pleistocene terraces of the rio cinca river in the southern pyrenees this river runs transverse to the main thrust fault structures and is a major conduit for sediment delivery to the ebro basin detailed field mapping combined with long profile and palaeohydraulic reconstructions yields a comprehensive picture of changes in palaeoriver character during the plio pleistocene as the area is over 150 km from the basin outlet in the mediterranean sea changes in base level are unlikely to have influenced terrace development although tectonic activity has exerted a strong control on the position of the river the main period of thrust propagation pre dates the terraces and activity has waned from the pliocene through to the present it is concluded that the main control on incision in this area is climate through its influence on sediment supply rivers which are starved of sediment by climate change will have the power to incise whereas aggradational phases are linked to periods of increased sediment flux

holocene paleoearthquakes of the daqingshan fault detected from knickpoint identification and alluvial soil profile abstract are there any effective methods to reveal paleoearthquakes on normal faults except traditional trenching technique in this paper we study holocene paleoearthquakes of the daqingshan fault which is a normal fault along the daqingshan piedmont of inner mongolia in china we identify knickpoints from stream profiles and study alluvial soil profiles to reconstruct the holocene paleoearthquakes of the fault from the fault s footwall we extract 25 gullies from irs p5 dem data and identify knickpoints in the profile that result from fault motion disturbing each channel we combine the retreat distances and the knickpoint retreat rates to determine each knickpoint s forming time we study alluvial fan outcrops that contain various paleosol sequences as three distinct holocene paleosols developed in the daqingshan piedmont alluvial fans we assume that the soil profile development was interrupted by fault activity preserved by interbedded gravel between the paleosols the gravel layer between two adjacent paleosol layers represents material transported there after a paleoseismic event thus we date paleosol layers which are above and below the gravel layer to constrain paleoseismic events since trenches had been made by our predecessors along the fault to reveal the holocene paleoearthquakes we identify the holocene paleoearthquake records from both sides of the fault and then compare the results with the results from the trenches the final result demonstrates that the knickpoints sequence in the footwall and the paleosols ages in the hanging wall correspond very closely with the holocene paleoearthquakes along the daqingshan piedmont fault methods in this paper have future application value to study paleoearthquakes on other normal faults with similar structure to the daqingshan fault

fluvial dynamics of an anabranching river system in himalayan foreland basin baghmati river north bihar plains india abstract anabranching river systems are now regarded as a separate class in river classifications owing to their distinctive morphological hydrological characteristics and fluvial processes a better understanding of anabranching rivers still needs detailed data from different environmental and geographical settings this paper presents a detailed account of an anabranching river system from the himalayan foreland basin the baghmati river system from north bihar plains eastern india provides a typical example of an anabranching river system located in the interfan area between the kosi and the gandak megafans the river system is braided in upstream reaches and meandering in downstream reaches but the midstream anabranching reach is characterized by low width depth ratio 11 16 gentle gradient 0 00018 0 00015 variable peak discharge frequent flooding and high sediment load the anabranching in the midstream reaches is a response to its inability to transport high sediment load due to gentle channel slope and dominance of aggradation process the development of anabranches is related to rapid and frequent avulsions of the river channels with eight major avulsions observed in the 30 km wide floodplain in the last 230 years the decadal scale avulsion history of the baghmati river system makes it hyperavulsive and the major causative factors for such channel instability are sedimentological readjustments and active tectonics in the basin area

geothermometry geobarometry and the al2sio5 triple point at mt moosilauke new hampshire the distribution of aluminum silicate minerals in pelitic schists constrains pressure and temperature conditions during the acadian orogeny to have been approximately those of the al 2 sio 5 invariant point thus providing an excellent opportunity to evaluate the internal consistency of a variety of published geothermometers and geobarometers with the al 2 sio 5 invariant point of holdaway 1971 four fluid independent equilibria yield p t estimates consistent with holdaway 1971 two fluid dependent equilibria yield internally consistent but unrealistically high temperatures our data are consistent with the conclusions that 1 only pyrope grossular mixing in the quaternary garnet system is significantly non ideal and 2 the activity coefficient for the anorthite component in plagioclase is approximately 2 at triple point p t conditions modified journal abstract

a discussion of alluvial sandstone body characteristics related to variations in marine influence middle jurassic of the cleveland basin uk and the implications for analogous brent group strata in the north sea basin

neotectonics and channel evolution of the lower ivinhema river a right bank tributary of the upper parana river brazil abstract the ivinhema river an important right bank tributary of the upper parana river cuts a series of terraces geomorphic surfaces floodplains and associate features through terrace mapping sediment composition absolute 14 c tl dating and morphostructural analysis this paper presents the composed longitudinal profile and the structural analysis of the lower course of the ivinhema river the tectonic model of the study area constitutes a sequence of nw tilting fault blocks formed from antithetic faults that control channel sinuosity longitudinal profile floodplain distribution and valley asymmetry the area began to be structured during the paleocene with formation of the oligomict conglomerate probably under an arid climate another tectonic reactivation in the mio pliocene boundary defined the divides of the upper parana and paraguay river basins with formation of the polymict conglomerate an active depositional phase taken place at the tertiary quaternary limit produced the massive reddish clayey sand sediments very common in the area during the late pelistocene 42 5 1 7 and 31 1 1 7 ka bp the parana and ivinhema rivers constructed a sedimentary sequence of gravelly sand deposits in a braided channel environment at the beginning of the holocene a new tectonic pulse lifted up a group of blocks parallel to the parana river valley developed a series of antithetic faults tectonic intensity associated with the pluvial stage hypsithermal phase between 8 and 6 ka changed the channel pattern of the river from braided to meandering channel evolution during the late pleistocene and holocene was also influenced by climatic changes

a 12 000 year record of vertical deformation across the yellowstone caldera margin the shorelines of yellowstone lake the 600 ka yellowstone caldera exhibits several signs of unrest the most evident of which is historic ground deformation including both uplift and subsidence we document deformation in the area of the southeastern caldera across 12 000 years using the postglacial shoreline terraces of yellowstone lake raised shoreline elevations were interpreted from 230 leveling profiles surveyed across flights of terraces with an accuracy of 0 5 m of about 11 recognizable terraces the five most continuous raised shorelines were correlated around the lake basin to reveal deformation patterns shoreline ages are based on minimum and maximum limiting radiocarbon and obsidian hydration dates each terrace is interpreted as representing an episode of uplift 1 kyr 1 of the caldera interior and subsequent subsidence with little net volume change this cyclic behavior may result from magma emplacement and subsequent withdrawal or cooling and crystallization and or episodic trapping and release of magmatic fluids evolved during cooling and crystallization in a self sealing reservoir as hypothesized by dzurisin et al 1990 early postglacial shoreline deformation reveals substantial intracaldera subsidence possibly reflecting cooling and loss of trapped hydrothermal fluids extension along north south trending normal faults and related structures is also apparent in early to middle postglacial deformation both inside and outside of the caldera margin including downwarping and local faulting of hot weak intracaldera crust net deformation over the past 3 kyr has been dominantly up within the caldera interior and slightly down along the caldera rim relative to the extracaldera region this uplift is roughly similar to the historic pattern and may largely represent the effects of the most recent inflation episode subtraction of the total estimated magnitude of inflation in this episode suggests that the overall trend of postglacial deformation has been subsidence the cause of this trend is undetermined but is most likely related to the effects of regional extension and long term cooling within the yellowstone caldera

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 owens river as a tiltmeter for long valley caldera california in the lower 11 km of its course around the resurgent dome of long valley caldera the owens river displays two parallel meander belts comparable in meander wavelength and amplitude but unequal in age elevation and discharge it appears the two belts take turns carrying the river s flow depending on whether the dome is inflating or subsiding the inboard belt some 200 300 m closer to the dome and now 30 60 cm higher in elevation contains an underfit stream and is now being abandoned the outboard channel formed in a series of avulsions apparently induced by recent uplift of the dome in the upper 4 km of the two channel reach avulsion occurred between 1856 and 1878 as inferred from the original u s coast and geodetic survey mapping in the caldera avulsion had already occurred by 1856 in the lower 4 km of the river suggesting a possible migration of the center of uplift through time muted remains of older oxbows in the outboard meander belt indicate an earlier occupancy by the river and thus an

analysis of the interaction between neotectonic and surface processes in a low land intracratonic setting of south america abstract the quaternary sedimentary record in the continental interiors has generally been studied taking into consideration the climatic forcing however episodes of uplift controlling the development of landforms have often been dismissed the interiors of continents are typically considered to have low deformation rates lower than the rates of exogenous processes deformation in the middle of the pampean plains an intracratonic setting of south america has been observed to have generated an elevated area surrounded by lowland plains this elevated area is susceptible to fluvial erosion from this fact we developed a geomorphologic modelling constrained from geomorphic markers in order to estimate the relative incidence of the different factors that control erosion in lowland landscapes an adapted erosion code was employed which combines fluvial incision equation the stream power law an uplift function spatially distributed and the hillslope diffusion equation a low dem was achieved for restoring an initial non deformed topography affected by low fluvial incision it represents a palaeosurface chrono stratigraphically constrained the estimation of the model parameters was achieved by applying the inversion method the best fit between the numerical solution calculated topography and the measured topography simulated by means a dem was approached by comparison of the stream longitudinal profiles the yield numerical approach suggests that a geomorphological modelling based on the stream power law is possible to be applied in low land landscapes for this a large scale change of the magnitude of the processes modelling the landscape should be expected in comparison with mountain erosional environments remarkably low k empirical values k 5 10 6 6 10 6 yr 1 suggest that the extremely low slopes exert a larger influence on the stream power in low land landscapes also the diffusion coefficient d values resulted largely lower 3 10 4 1 9 10 3 cm 2 yr than presented in tectonically active landscapes 0 03 cm 2 yr regional uplift rates can be higher 0 35 mm yr than it is generally expected in low uplift rate settings 0 1 0 25 mm yr these estimations evidence highly dynamic surface and tectonic processes controlling the landscape evolution over intermediate time scales in an intracratonic setting

palaeoenvironments of the late miocene pruedo basin implications for the uplift of the central pyrenees the nature structure and extent of a palaeo basin sedimentary infill exposed in the aran valley central pyrenees was studied by combining stratigraphical and biostratigraphical analyses and an audio magnetotelluric survey the basin developed on top of a pre existing peneplain and was formed by the north maladeta fault activity the fluvio palustrine sequence filling the basin was at least 100 m thick specimens of the taxon hippuris cf parvicarpa nikitin were identified for the first time in a european palaeoflora the palynological and carpological analyses allowed us to 1 constrain the age of the basin infill as vallesian 11 1 8 7 ma 2 characterize the vegetation of the belt surrounding the basin as a mainly temperate to warm temperate assemblage and 3 estimate the palaeoaltitude of the site at between 700 and 1000 m which leads to an altitude change of 900 1200 m for the north maladeta fault downthrown block and 1640 1640 m for the upthrown block these data allowed us to estimate the regional uplift of the area at between 0 08 and 0 19 mm a 1 the different exhumation values obtained by other researchers for sites located at both sides of the north maladeta fault are in agreement with its activity as a normal fault since the late miocene supplementary materials details of the data acquisition processing and modelling for the porera profile are available at www geolsoc org uk sup18551

garnet orthopyroxene plagioclase quartz barometry refinement and application to the english river subprovince and the minnesota river valley recent experimental theoretical and thermodynamic studies permit better calibration of two reactions for geobarometry grossular pyrope quartz anorthite enstatite grossular almandine quartz anorthite ferrosilite if both reactions are applied using the same thermodynamic data and activity models they should yield the same pressure for a given garnet pyroxene plagioclase quartz assemblage application to a variety of high grade terrains generally yielded excellent results however poor results have been obtained for high fe rocks which can be traced to errors in activity models for garnet and or pyroxene either a two site ideal mixing model for orthopyroxene cf wood and banno 1973 underestimates enstatite activity for high fe orthopyroxenes or the ganguly and saxena 1984 model overestimates pyrope activity in low mg garnets

response of plio pleistocene alluvial systems to tectonically induced base level changes vera basin se spain tectonics are perceived to be a major control on the positioning and long term evolution of alluvial systems by increasing slope gradients through uplift and tilting or by changing local base level incision can be stimulated leading to a switch in the active area of sedimentation an example of such a sedimentary response to tectonic activity is provided by well exposed late pliocene early pleistocene alluvial sediments of the salmeron formation from the western margins of the vera basin se spain early stage palaeogeographic reconstructions demonstrate the occurrence of two alluvial fan bodies with distinct palaeocurrent and provenance signatures that suggest sediment source areas from the north sierra lisbona and south sierra de bedar of the study area late stage reconstructions suggest fan abandonment and indicate the occurrence of a braided river system sourced from the sierra de bedar in the south proximal parts of this braided river are incised by up to 100 m into underlying fan sediments sourced from the sierra de bedar in distal areas incision is negligible and the braided system forms a conformable sedimentary succession with underlying fan sediments sourced from the sierra lisbona the switch from alluvial fan to braided river sedimentation and the spatially variable patterns of incision into the alluvial fan bodies can be accounted for by a phase of deformation which affected the vera basin during the early pleistocene extensional faulting resulted in uplift and subsidence leading to localized tilting of depositional surfaces in distal areas of the southern fan increased stream power resulted in headward incision through mid and proximal fan areas once the system became fully trenched distal base level controls became effective in generating an enlarged catchment area and continuing incision the resultant changes dramatically increased both sediment and water discharge to the alluvial system and a switch to braided river sedimentation

sedimentology and alluvial architecture of the bajo barreal formation upper cretaceous in the golfo san jorge basin outcrop analogues of the richest oil bearing fluvial succession in argentina abstract this study addresses the sedimentology architecture and dimensions of fluvial deposits in the bajo barreal formation upper cretaceous in the codo del senguerr anticline golfo san jorge basin argentina the stratigraphic framework of the 450 650 m thick alluvial succession was carried out through description and interpretation using 18 detailed sedimentary logs along a 4 5 km wide exposure where 314 fluvial channels were analysed the bajo barreal formation is a high accommodation fluvial succession dominated by fine grained floodplain deposits with isolated to vertically stacked sheet like low sinuosity or braided fluvial channels of limited lateral mobility clustered in several coeval channel belts in which fluvial channels were relocated by avulsion the lower member consists of reworked ash fall materials preserved in floodplain areas 78 floodplain sandstones 4 and fluvial channels 18 the mean thickness of sandbodies is 2 96 m n 118 and mean true width is 112 m mean w t 43 with thicker and wider sandbodies in upper levels of the member the upper member consists of grey siltstones and mudstones preserved in extensive lowland areas 78 and fluvial channels 19 with scarce preservation of sandstones in the proximal floodplain 3 fluvial channels are narrow low sinuosity sheets with comparable thickness mean 3 21 m n 196 but greater width than those of the lower member mean width 147 m mean w t 50 paleoflow data from 298 fluvial sandbodies indicates a paleoflow direction toward the se az 112 rivers flowed parallel to inherited early cretaceous normal faults and are oriented to high angle 70 to the current axis of the codo del senguerr anticline suggesting that the uplift of the anticline occurred after the deposition of the formation the variation in geometry of fluvial channels in both members of the bajo barreal formation could help in planning and developing primary and or enhanced oil recovery projects in nearby oilfields and provide data necessary for modelling the subsurface connectivity of hydrocarbon reservoirs

geomorphic observations of rivers in the oregon coast range from a regional reconnaissance perspective abstract changes in long profile gradient gradient index pseudo hypsometric integral valley incision and sinuosity fractal dimension for rivers in western oregon were studied to determine their usefulness in assessing an hypothesis of differential uplift within the coast range all data were gathered from topographic quadrangles and geologic maps and so the results of this paper are limited to the description of river forms with only limited interpretations rivers were naturally divided into three groups those in the western coast range the eastern coast range and the klamath and cascade ranges and differences in river morphometry were generalized rivers in the western coast range had more divergent characteristics whereas those in the other groups were more similar within each group for example long profiles of western coast range rivers had diverse forms but in the other groups long profiles were similar within the group pseudo hypsometric integrals had a wide scatter in the western coast range but in the other ranges the pseudo hypsometric integral was more narrowly defined valley entrenchment and high sinuosity were common in the western coast range and were less visible in the eastern coast range these regional generalizations do not hold for the central coast range near 44 5 n where the yaquina and marys rivers are located in the eastern coast range the marys river is unique in that it has a convex bulge in its long profile does not have an increasing valley floor width to valley height ratio downstream and has a high sinuosity fractal dimension in the western coast range the yaquina river is unique in that it has a smoothly decreasing long profile has a very low pseudo hypsometric integral and does not have a decreasing valley floor width to valley height ratio downstream there may be many explanations for these observations but these observations are also consistent with tectonic interpretations that the central western coast range is the locus of synclinal tilting and that the entire oregon coast is experiencing landward tilting and uplift

controls on channel sinuosity changes a case study of the tisza river the great hungarian plain abstract the planform geometry of the tisza the trunk river of the subsiding great hungarian plain is studied by reconstruction of the last pre regulation river course the thalweg sinuosity has been computed for the main alluvial section of the river remarkable sinuosity changes have been found to correlate with discharge and sediment load changes at the inflow of tributaries as well as with active deformation areas like differential subsidence and wrench fault zones analysing the change of the river pattern a new discrimination line has been derived which separates the meandering zone on the classic slope vs discharge diagram into two subzones the first subzone lower slope values corresponds to a range of true self organized meandering the second subzone higher slope values corresponds to a range of unorganized meandering this is a range where river sinuosity decreases although the channel slope increases in the case of the tisza river this subzone equals to the wandering river pattern

active tectonics and geomorphology in the sone ganga alluvial tract in mid ganga basin india active tectonics plays a major role in landscape evolution by bringing changes in topography and channel slopes the alluvial plains in ganga basin are divided into a number of tectonic blocks by several active subsurface faults the associated disturbances along these faults have given rise to a distinctive fluvial regime and geomorphology in the region in sone ganga alluvial plain in parts of south ganga plains in middle ganga basin the sone and ganga rivers have responded to the ongoing tectonic deformation in the area the study reports a classical example of tilt induced avulsion and channel migration during holocene from the parts of south ganga plains within the extensional half graben between east patna fault epf and west patna fault wpf the rate of lateral tilt appears to control the style of channel movement with gradual migration occurring at low tilt rates and avulsion at higher rates the river sone lying laterally close to the line of uplift has undergone avulsions at different times of tilting whereas the ganga river located at the lower parts of the tilting block away from the line of uplift has migrated in the down tilt direction various fluvial anomalies such as gradient reversals in the longitudinal profile of channels sinuosity variations channel incision frequency in the braid bar distribution and variation in the cross sectional parameters of the channels most probably created by tectonics have been studied satellite images and maps coupled with relative bank height measurements and other geomorphologic studies in field have helped in identifying such fluvial signatures and their relevance to tectonics the subsurface faults in the sone ganga plains cut across and also run parallel the river channels showing the effects of transverse and lateral tilting manifested in channel avulsions and migrations

evolving fluvial style in the kekiktuk formation mississippian endicott field area alaska base level response to contemporaneous tectonism the hydrocarbon reservoir at endicott field offshore from the sagavanirktok delta in northeastern alaska is found in the upper mississippian visean kekiktuk formation the trap is bounded by the northwest southeast trending tigvariak and mikkelson bay faults and the younger east west trending niakuk fault the kekiktuk comprises sandstones siltstones and mudstones with locally significant coals and conglomerates and is subdivided into three major reservoir zones based on the relative dominance of these lithologies zone 1 the lowest comprises mudstones siltstones and coals with subordinate isolated sandstones and represents deposition within a low lying swamp plain with very low net to gross ratio this zone is considered to be effectively nonreservoir major movement on the mikkelson bay and tigvariak faults created a half graben with uplift to the north and east and a very significant drop in base level this change resulted in fairly widespread deposition of zone 2 medium to coarse grained sandstones from sandy bed load braided streams however those sandstones thin significantly to the west away from the faults continuing tectonism at this time created local shifts in base level manifest as diversion of streams widespread abandonment and subsidence leading to the creation of a arge lake the lacustrine deposits are widespread and effectively divide zone 2 into two subzones those subzones are mappable sheet sandstones and constitute the best reservoir at endicott field in terms of net to gross ratio porosity permeability and sandstone connectivity base level shows evidence of rising dramatically at the end of zone 2 this rise is attributed to continuing tectonism within the basin and is particularly associated with the east west trending mid field fault system at endicott field as well as ongoing activity on the tigvariak mikkelson bay fault system thus at the base of zone 3 subzone 3a in the southern and eastern parts of the field the rocks are mudstones and widespread coals and contain at least one unequivocally marine mudstone these rocks are lower delta plain interdistributary bay fill deposits with rare distributary channel sandstones north and west of the mid field fault system the marine mudstone is absent and the facies changes significantly with the loss of dominant coal and a concomitant increase of dist ibutary channel sandstones reservoir properties of subzone 3a including connectivity are significantly different in this area subzone 3b is a thick accumulation of fine grained alluvial overbank deposits within which occur rare isolated anastomosed channel sandstones of limited connectivity this subzone makes minimal contribution to endicott field reserves subzone 3c is characterized particularly in its upper part by well developed fining upward cycles indicating mature meandering streams the relationships between these two highest subzones of the kekiktuk at endicott field indicate they represent an aggradational episode initiated by tectonically induced avulsion and set against a background of rising base level to the west at some distance from the tigvariak mikkelson bay f ult system zone 3 is much thinner than at endicott field and is dominated by mudstones and coals this evidence emphasizes the control that contemporaneous tectonism related to those faults had on sediment especially sandstone distribution within the kekiktuk formation base level changes can be identified within the end page 1723 kekiktuk formation in the north slope subsurface by careful lithofacies analysis and an awareness of key constraining indicators such as are revealed by palynology paleontology and structural geology by analogy with shallow marine rocks sequence stratigraphic concepts may be extended to continental successions however one must approach such problems with a full awareness of the impact of tectonism on base level and basin development

a detection method of subrecent to recent tectonic activity in the anticlinal system of the northern negev israel geomorphological and geophysical methods combined with borehole information were employed to search for possible subrecent small scale vertical movement along the anticlinal fold belt of the central negev israel such tectonic deformation might indicate displacement on the buried reverse faults underneath the anticlines

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

active tectonics of eastern segment of the south wagad fault zone kachchh western india abstract the present study describes the active tectonic features of the eastern segment of the south wagad fault zone swfz of the kachchh rift basin krb the swfz defines the southern margin of the wagad uplift with a series of small domes and anticlines forming a low hill range geomorphologically the swfz is expressed by the presence of the south wagad hill range to the north and the south sloping samkhiyali and lakadia plains to the south the easternmost part of the swfz consists of domes and anticlines having a rugged topography which comprises of mesozoic to neogene rocks and is practically unexplored as far as their active tectonic characterizations are concerned the geomorphic expression of the swfz in the eastern segment consists of the gagodar kanmer guan and mardak domes and anticlines they are exposed as a series of linear mounts projected amidst the little rann of kachchh and surrounded by the alluvial sediments of easterly flowing rivers as well as the rann sediments the active nature of the eastern swfz is portrayed by warping flexuring alluvial fans tilted quaternary deposits scarps gullied surfaces slickensides and knickpoints presence of wave cut cliff and notches at mardak bet suggests that the eastern segment of swfz is marginally uplifted during middle to late holocene period we provided a detailed morphotectonic map of the eastern segment of swfz which can be used for future infrastructural development town planning and seismic hazard assessment in the region further the study suggests that the seismically silent eastern segment of the active swfz is capable of generating a large magnitude earthquake similar to the 2001 bhuj earthquake or the 1819 allah bund earthquake in the future owing to long term stress accumulation

drainage area and incised valley fills in texas rivers a potential explanation abstract the largest rivers draining to the gulf of mexico in texas are at more advanced stages of valley filling than rivers with smaller drainage areas with corresponding differences in alluvial morphology and architecture and avulsion style this seems to imply that the larger fluvial systems either produce more sediment relative to the accommodation space in the alluvial valleys or that they have undergone longer periods of valley aggradation however it is not clear that either of these is the case this paper presents a theoretical analysis showing that fluvial systems with larger drainage areas can produce more advanced stages of infilling than those with smaller drainage areas but with identical histories and sediment production per unit area due to the nature of the scaling relationships between drainage basin area and incised valley size and between basin area and sediment yield data for rivers in the region shows a strong linear relationship between valley width and drainage area the nonlinear relationship between drainage area and proportion of the incised valley filled is somewhat weaker but still significant and major deviations are readily explained in terms of local inherited morphology or tectonic features results show that major differences in the degree or stage of valley filling could occur due to differences in drainage basin size alone this indicates caution in interpreting incised valley fills of drainage basins of different sizes in terms of sediment supply

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

initiation and evolution of gullies along the shoreline of lake huron over one hundred gullies are deeply incised into algonquin bluff along the eastern shoreline of lake huron aerial photographs between 1930 and 1992 were used to measure temporal changes in area and length of a sample of forty four gullies regression analysis shows that gully area and length have increased in a linear fashion and that gully initiation occurred in the nineteenth century gully initiation coincides with deforestation and settlement of the area surface drainage was redirected into drainage ditches concentrating the flow and enhancing gully erosion natural processes associated with climatic fluctuations are probably insufficient to cause gully initiation but may contribute to ongoing gully expansion

interpreting the stratigraphic architecture of fluvial systems in internally drained basins models for fluvial architecture tend to focus on the effects of sea level oscillation and syndepositional tectonics in creating and removing accommodation space and determining the relative distribution of channel and overbank deposits in the stratigraphic record however in basins of internal drainage sea level change does not exert any influence and in settings where basin centre lakes are very shallow fluctuations in lake level have little impact on the fluvial system if there is variation in tectonic subsidence across the area this will affect depositional patterns but otherwise subsidence does not play a role in affecting sediment distribution in an endorheic setting the luna and huesca systems were deposited in the endorheic ebro basin at a time when deformation in the adjacent pyrenees had largely ceased hundreds of metres of fluvial and lacustrine sediment accumulated raising the level of the basin centre by stratigraphic aggradation and back filling of hinterland valleys during aggradation the systems appear to have maintained a constant slope across the fluvial profile the resulting stratigraphic architecture is well displayed in the ebro basin and provides a case study of architectural patterns in endorheic settings which is in marked contrast to those described from fluvial successions formed in externally draining systems

geothermometry and geobarometry in pelitic rocks of north central wopmay orogen early proterozoic northwest territories canada pressure and temperature estimates for the pelitic schists and gneisses along the east flank of the hepburn batholith early proterozoic have been determined by means of an electron microprobe study of coexisting garnet biotite plagioclase and cordierite garnet biotite geothermometry using recent calibrations yields results between 560 and 765 c consistent in spatial distribution with andalusite sillimanite and sillimanite k feldspar metamorphic zones calibrations of the garnet cordierite equilibrium give temperature estimates on average 23 c lower both sets of temperature estimates for the garnet cordierite bearing assemblages are consistent with the theoretical stability field of these rocks geobarometry based on the 3 caal 2 si 2 o 8 ca 3 al 2 si 3 o 12 2 al 2 sio 5 sio 2 equilibrium outlines a broad pressure culmination with variation from 2 6 to 5 2 kbar the p culmination coincides with a structural plunge culmination as outlined by the change in plunge azimuth of folds of bedding by a re entrant in the trace half window of a major premetamorphic thrust fault and by a narrowing of the synmetamorphic funnel shaped hepburn batholith garnet cordierite geobarometric calibrations generally give pressure determinations in the same range as the grossular anorthite results the spread in the garnet cordierite pressure estimates from various calibrations however points to the need for considering the role of water when using the garnet cordierite geobarometer

geological controls on the formation of alluvial meanders and floodplain wetlands the example of the klip river eastern free state south africa tooth s mccarthy t s brandt t hancox p j morris r 2002 geological controls on the formation of alluvial meanders and floodplain wetlands the example of the klip river eastern free state south africa earth surface processes and landforms 27 8 797 815

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

middle late holocene river terraces in the erhjen river basin southwestern taiwan implications of river response to climate change and active tectonic uplift abstract we reconstruct the holocene river history of the erhjen river area 140 km 2 by correlating river terraces aided by 28 radiocarbon dates multiple terraces developed in the lower erhjen river since the middle holocene they converge downstream to the coastal plain the rates of channel incision into bedrock calculated from these terraces at yuehshihchieh are 7 8 mm year during ca 5 7 2 5 ka 5 cm year during 1 5 1 3 ka and 1 cm year since 1 ka the last is close to the average incision rate since middle holocene meanwhile only a single but wide middle late holocene paleo floodplain was developed in the upper erhjen river it was completely abandoned only after 0 8 ka likely following an episode of base level fall starting from the coastal plain based on the apparent downstream and upstream convergence of these dated terraces we identify a doming structure or anticline within the basin which results in a tilt rate of 10 6 to 10 7 per year in the lower erhjen river valley the major terraces here had different initial long profiles which implies that a critical graded long profile may not be a prerequisite for formation of a wide erosional terrace surface instead we propose that these terraces were initiated by a series of catastrophic rainfall events probably climatic related which brought a large amount of bedload from hillslopes to prevent the channel from incising when valley widening was facilitated by high discharge runoff we find that not only terrace surface formation but also channel incision can be strongly controlled by climatic driven discharge and bedload conditions as suggested by the contrast of bedrock incision rates we observe at yuehshihchieh apparently the climate and its effects on the landscape cannot be regarded as constant during the holocene even in a humid tropical area like taiwan however such a fluctuation of climate could only be recorded in a setting where rivers have a high tendency to incise so that multiple terraces can be created the lower erhjen river that is characterized by active tectonic tilting is an example of this setting

analogue modeling of transverse drainage mechanisms fifteen physical experiments on a stream table replicated four general mechanisms proposed to explain transverse drainage development namely antecedence superimposition overflow and piracy the experimental design encompassed multiple strategies to effectively replicate the different mechanisms these experiments roughly emulate natural fluvial processes including aggradation lateral erosion degradation knickpoint retreat ponding and overflow the experiments address landscape morphology and depositional field criteria associated with antecedence overflow and piracy antecedence experiments showed that defeat of streams by a tectonically growing structure could result from a combination of upstream ponding and diversion into a trunk drainage insufficiently fast retreating knickpoints and downstream deposition of eroded sediments piracy can result from stream aggradation until it overtops a low divide by headward erosion of a stream through a divide and by sapping processes for piracy driven by headward erosion asymmetrically sloped ridges allow the drainage divide across the ridge to retreat from headward erosion but a symmetric divide hinders the ability of a stream to retreat across the ridge apex aggradationally driven piracy is potentially hindered because the slope across the divide needs to be sufficiently steep compared to the uncaptured stream otherwise deposition occurs across the divide and a levee is formed which prevents capture for transverse drainages produced by overflow knickpoints retreat across the overflow outlet producing a high probability of downstream flooding a positive feedback develops where added discharge to the drainage from lake water increases erosion and knickpoint retreat further eroding and undermining the basin outlet and releasing even more lake water the result is rapid incision and dramatic flooding downstream of the bedrock high during lake outlet erosion two superimposition experiments were unsuccessful most of the field criteria for antecedence overflow and piracy were either directly replicated or implied based on observations during each experimental run

stream channel convexity induced by continuous base level lowering the dead sea israel abstract the dead sea level has dropped from 388 4 m in 1896 to 417 2 m in 2004 and continues to fall rapidly reaching a record of 1 m y drop such a dramatic base level fall on time scales of several tens of years makes the dead sea area a unique field laboratory the aim of this study is to examine the effect of the lowering dead sea as a base level on the longitudinal profiles of channels on the formation of knick points and on the sinuosity field studies were made along the lower courses of creeks which drain lakeward precise longitudinal profile measurements and their fitting to linear and logarithmic curves show they are planar to slightly convex the short convexity the absence of hydrological or lithological control and former experimental results of profile response to base level fall suggest that the convexity results from the recent continuous rapid drop of the dead sea the convexity is also an inheritance of the paleo morphology i e the original convex front of the fan deltas and coastal scarps following channel incision slope displacement and diffusion the erodible substrate and the high stream power prevented preservation of nickpoints along the main channels sinuosity of the meandering thalwegs remained low 1 1 1 2 indicating no response to the base level lowering along the steep slopes although the stream channels are incised in soft sediments the base level induced entrenchment dies out within 1000 m or less from the receding shoreline the channel profiles demonstrate different phases of adjustment to the lowering base level the uniqueness of the dead sea case is that contrary to former field and experimental studies the system is in a continuous relaxation period without reaching a final adjustment the channels are trapped in their convex form following a rapid on going base level fall upon exposed paleo fan deltas

the influence of valley aggradation and listric normal faulting on styles of river avulsion a case study of the brazos river texas usa abstract the holocene avulsion history of the lower brazos alluvial valley of east texas usa was studied using 10 drill cores 26 radiocarbon dates aerial photos and a digital elevation model this study shows that two long term processes aggradation and localized valley tilting along a normal listric fault are responsible for generating two styles of avulsion the first process precedes avulsion by progradation while the second process precedes avulsion by annexation as valley aggradation migrated updip over the last 7 5 ka three regional backstepping avulsions occurred along the lower 140 km of the valley and each generated sizable deposits a pattern emerges of landward stepping progradational avulsions tracking the locus of valley aggradation and of valley aggradation migrating inland even after the rate of sea level rise diminishes at the same time several local nodal avulsions occurred between 50 and 55 km updip of the current highstand shoreline but generated no observable deposits geomorphic evidence indicates that since the late pleistocene active movement along a previously undocumented normal listric fault has occurred at the location of the nodal avulsion these two long term processes do not operate mutually exclusive of each other to promote avulsions rather they operate concurrently only aggradation promotes avulsions that affect floodplain alluviation although the total volume of these deposits comprises a small portion of the valley fill

contemporaneous subsidence and fluvial channel sedimentation upper mannville c pool berry field lower cretaceous of alberta upper mannville c pool is a small oil pool which produces from lower cretaceous fluvial sandstones in berry field southeastern alberta ultimate oil reserves of the pool are 5 8 million m3 of oil contained within a sandstone body about 7 5 km long and 2 km wide the pool is unusual for its occurrence on the flank of a local structural high within a large regional structural depression sandstone distribution rather than present day structure dictates the occurrence of hydrocarbons yet the distribution of sandstones was controlled by structure a fluvial channel was diverted into an area of synsedimentary faulting or downwarping which then controlled the depositional form of an asymmetric wedge of channel levee and crevasse splay sands the most likely cause of subsidence was differential salt solution regionally the berry area lies along the margin of several devonian salt formations which are known to have undergone partial solution lateral migration of the locus of salt solution and hence subsidence through time produced both the facies and structural configurations observed in this oil pool

fluvial geomorphology and neotectonic activity based on field and gpr data katrol hill range kachchh western india abstract the largely rocky and rugged landscape of the katrol hill range composed of mesozoic rocks and structurally controlled occurrences of quaternary sediments is delimited to the north by north facing range front scarps of the seismically active e w trending katrol hill fault khf the landscape and drainage characteristics of the katrol hill range are documented together with ground penetrating radar gpr investigations along the khf to delineate its nature for understanding neotectonic activity in the contemporary tectonic setting the overall geomorphology is controlled by the south oriented tilt block structure of the range indicated by its pronounced influence on the morphology and drainage network the drainage comprises north flowing and south flowing rivers with the drainage divide located close to the northern edge of the range which also marks the highest topographic elevations the narrow zone between the crest line and the drainage divide has been identified as the zone of gorges where gorges and deeply incised fluvial valleys have been formed within quaternary sediments by the various north flowing streams the quaternary sediments consist of bouldery colluvial deposits in front of the range front scarps valley fill miliolites and alluvial deposits of late pleistocene age within the back valleys and scarp derived colluvium forming the youngest deposit based on the geomorphic and stratigraphic evidence three major phases of quaternary tectonic uplift in the katrol hill range are inferred the oldest pre miliolite phase middle pleistocene was followed by a prominent phase of fluvial incision with formation of gorges during early holocene and then by the last one during late holocene continuing at present uplift of the range occurred in well marked phases during the quaternary in response to differential uplift along the khf under an overall compressive stress regime gpr investigations at selected sites show that the khf is a steep south dipping reverse fault near the surface which becomes vertical at depth this suggests neotectonic reactivation of the khf under a compressive stress regime responsible for active southward tilting of the katrol hill range

late quaternary activity of the scorciabuoi fault southern italy as inferred from morphotectonic investigations and numerical modeling 1 following a detailed morphotectonic analysis of the fluvial terraces of the sauro river basilicata southern italy the present research documents for the first time the late quaternary tectonic activity of the scorciabuoi fault and discusses its inferred seismogenic potential on the basis of both remote sensing techniques and detailed field investigations four fill terraces have been recognized and mapped along the sauro valley showing differential cumulative displacements across the fault these terraces are genetically correlated with four highstand sea level periods following stratigraphic and geological age constraints and on the basis of the correlation with a sequence of marine and fluvial terraces characterizing the lower agri valley the sauro terraces likely formed between 80 or 100 ka and present the inferred long term slip rate of the scorciabuoi fault ranges between 0 5 and 1 0 mm a numerical simulations based on a crustal elastic deformation model also contribute to separate and tentatively quantify the regional uplift rate 1 0 1 4 mm a and to improve the overall reconstruction of the late quaternary evolution of the area the synergic but distinct roles played by eustatism regional uplift and faulting are eventually appreciated

the role of late pleistocene holocene tectono sedimentary history on the origin of patches of savanna vegetation in the middle madeira river southwest of the amazonian lowlands abstract savanna patches are features of the amazonian landscape that have been long under intense debate but there are still questions about the main factors that have determined their establishment and evolution within the rainforest matrix in particular their geological substrates were poorly documented the aim of this work is to reconstruct the tectono sedimentary history of four savanna patches in the middle madeira river southwest amazonia and discuss its potential control over the development of the savanna communities the approach consisted in the integration of geomorphological sedimentological chronological and floristic data the results revealed that the savanna substrates are sandy deposits aged between 118 9 and 35 6 ky overlain by late pleistocene to holocene muddier successions

late miocene quaternary volcanism tectonics and drainage system evolution in the east carpathians romania abstract middle miocene sarmatian convergence created the fold and thrust belt of the eastern carpathians of romania which subsequently experienced post collisional crustal deformation combined with calc alkaline and alkalic basaltic volcanism in late miocene quaternary time this deformation led to the rise of the c limani gurghiu harghita volcanic mountains and to the subsidence of the n s oriented intramontane borsec bilbor gheorgheni ciuc and brasov pull apart basins and the e oriented monocline related f g ras basin the regional drainage network is the composite of 1 older e se and s flowing rivers which cross the carpathians radiate towards the foreland and were probably established during the middle miocene sarmatian collision event 2 a more recent drainage system related to the contemporaneous development of the volcanoes and intramontaneous basins which generally drains westward into the transylvanian basin since late miocene time and has been capturing the older river system the older river drainage system has also been modified by late pliocene quaternary folding thrusting and monoclinal tilting along the pericarpathian orogenic front and by reactivated transverse high angle basement faults which cross the eastern carpathian foreland

heat capacities and entropies of andalusite and sillimanite the influence of fibrolitization on the phase diagram of the al 2 sio 5 polymorphs

gypsum scarps and asymmetric fluvial valleys in evaporitic terrains the role of river migration landslides karstification and lithology ebro river ne spain abstract most of the spanish fluvial systems excavated in tertiary evaporitic gypsum formations show asymmetric valleys characterized by a stepped sequence of fluvial terraces on one valley flank and kilometric long and 100 m high prominent river scarp on the opposite side of the valley scarp undermining by the continuous preferential lateral migration of the river channel toward the valley margin leads to vertical to overhanging unstable slopes affected by a large number of slope failures that become the main geological hazard for villages located at the toe of the scarps detailed mapping of the gypsum scarps along the ebro and huerva rivers gypsum scarps demonstrates that landslides and lateral spreading processes are predominant when claystones crop out at the base of the scarp while rockfalls and topples become the dominant movement in those reaches where the rock mass is mainly constituted by evaporites the dissolution of gypsum nodules seasonal swelling and shrinking and dispersion processes contribute to a decrease in the mechanical strength of claystones the existence of dissolution enlarged joints sinkholes and severely damaged buildings at the toe of the scarp from karstic subsidence demonstrates that the interstratal karstification of evaporites becomes a triggering factor in the instability of the rock mass the genesis of asymmetric valleys and river gypsum scarps in the study area seem to be caused by the random migration of the river channel in the absence of lateral tilting related to tectonics or dissolution induced subsidence once the scarp is developed its preservation depends on the physicochemical properties of the substratum the ratio between bedrock erosion and river incision rates and climatic conditions that favour runoff erosion versus dissolution

principles of drainage basin analysis from multisource data application to the structural analysis of the zaire basin abstract classifications which attempt to combine descriptive and genetic aspects of types of drainage basins must take into account the application of new techniques satellite imagery high precision topographic maps and digital terrain models in addition the use of new concepts such as neotectonics and drainage basin history will lead to a reassessment of classification schemes after a review of current classifications we propose a genetic scheme that is based on the development of drainage networks and which includes integration of local and regional scale perturbations state of the art methods of drainage basin analysis are applied to the zaire basin to provide new information on deep structures the influence of basin and block tectonics is revealed in the context of major late proterozoic shear faults which have been rejuvenated up to the present day this is demonstrated from an analysis of the drainage network in the light of geological and geophysical observations

evidence for post early eocene tectonic activity in southeastern ireland the role played by cenozoic deformation in denudation and landscape development in ireland has historically been difficult to assess because of the lack of widespread pre glacial cenozoic deposits onshore here we combine analysis of apatite fission track data and geomorphic observations to place constraints on the timing kinematics and magnitude of onshore deformation in southeastern ireland relationships between apatite fission track central age and elevation for samples from the wicklow and blackstairs mountains and tullow lowland suggest that these rocks record an exhumed apatite partial annealing zone which after cooling was dismembered by differential vertical displacements of up to several hundred metres we use inverted models of sample thermal history to show that samples across the region experienced very similar thermal histories up to and including a cooling event in late paleocene or early eocene time this effectively rules out strongly spatially heterogeneous denudation and implies that differential rock uplift occurred in post early eocene time the central age elevation relationships define at least three spatial domains with internally consistent apatite fission track data separated by known faults or topographic escarpments geomorphic analysis of these structures shows that patterns of catchment incision and sinuosity as well as the presence of antecedent drainage are best explained by differential vertical displacements at or near the domain boundaries the kinematics and magnitudes of these displacements are consistent with those implied by the apatite fission track results and are compatible with other examples of known cenozoic deformation from ireland and the adjacent continental margin

active crustal faults in the forearc region guerrero sector of the mexican subduction zone this work explores the characteristics and the seismogenic potential of crustal faults on the overriding plate in an area of high seismic hazard associated with the occurrence of subduction earthquakes and shallow earthquakes of the overriding plate we present the results of geomorphic structural and fault kinematic analyses conducted on the convergent margin between the cocos plate and the forearc region of the overriding north american plate within the guerrero sector of the mexican subduction zone we aim to determine the active tectonic processes in the forearc region of the subduction zone using the river network pattern topography and structural data we suggest that in the studied forearc region both strike slip and normal crustal faults sub parallel to the subduction zone show evidence of activity the left lateral offsets of the main stream courses of the largest river basins gps measurements and obliquity of plate convergence along the cocos subduction zone in the guerrero sector suggest the activity of sub latitudinal left lateral strike slip faults notably the regional left lateral strike slip fault that offsets the papagayo river near the town of la venta named la venta fault shows evidence of recent activity corroborated also by gps measurements 4 5 mm year of sinistral motion assuming that during a probable earthquake the whole mapped length of this fault would rupture it would produce an event of maximum moment magnitude mw 7 7 even though only a few focal mechanism solutions indicate a stress regime relevant for reactivation of these strike slip structures we hypothesize that these faults are active and suggest two probable explanations 1 these faults are characterized by long recurrence period i e beyond the instrumental record or 2 they experience slow slip events and or associated fault creep the analysis of focal mechanism solutions of small magnitude earthquakes in the upper plate for the period between 1995 and 2008 revealed that frequent normal faults sub parallel to the trench could be reactivated in the current stress field related to the cocos subduction moreover these features could also be reactivated by subduction megathrust earthquakes

neotectonic effects on sinuosity and channel migration belle fourche river western south dakota short term instability in the behaviour of a small meandering alluvial channel is identified from the relation between sinuosity and either floodplain slope or channel slope within 17 reaches along an 81 kilometre section of the belle fourche river in western south dakota in reaches 1 to 4 and 11 to 17 the channel is relatively stable and sinuosity varies inversely with channel slope in reaches 5 to 10 sinuosity is positively related to floodplain slope sinuosity increases markedly in reaches 5 6 and 7 which are immediately downstream from a discontinuity in the long profile of the floodplain in association with an increase in floodplain slope immediately upstream from the discontinuity bankfull channel depth and sinuosity decrease and the area of the floodplain reworked by meander migration between 1939 and 1981 increases in association with a decrease in floodplain slope channel behaviour in reaches 5 to 10 is best explained as a consequence of neotectonic activity as indicated by changes in elevation recorded along geodetic survey lines that cross lineaments that may delimit the eastern boundary of the black hills uplift sinuosity acts as a barometer of the effects of neotectonic activity on alluvial channels initial indications of channel and floodplain instability due to neotectonic activity may be derived from evidence of anomalously active channel migration as documented from photographic or topographic sources

imaging underwater neotectonic structures in the amazonian lowland previous documentation has proposed tectonic activity from the neogene to holocene as one important control on drainage development in the amazonian lowland however recording tectonic structures in this region has been challenging due to environmental difficulties including the low topography and dense vegetation cover that do not favor natural exposures for this reason the role of tectonics in determining river dynamics morphology and sediment deposition in amazonia has been suggested with caution despite limitations morphostructural lineaments have provided useful information to support fault reactivation in several areas of the amazonian lowland however further documentation is required to map the faults and describe their geometry this approach is essential to better understand the geotectonic model of this region in this work analyses of high resolution optical imagery of three amazonian shallow water lakes provided exceptional views of an abundance of linear features on the beds of the

quaternary evolution of the cordillera frontal piedmont between c 33 and 34 s mendoza argentina fil zarate marcelo aristides consejo nacional de investigaciones cientificas y tecnicas instituto de ciencias de la tierra y ambientales de la pampa universidad nacional de la pampa facultad de ciencias exactas y naturales instituto de ciencias de la tierra y ambientales de la pampa argentina

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

gypsum karstification induced subsidence effects on alluvial systems and derived geohazards calatayud graben iberian range spain abstract the karstification of the tertiary gypsum formations in the calatayud graben has given rise to synsedimentary and postsedimentary subsidence phenomena in both the neogene sediments of the endorheic graben fill and in the quaternary alluvial sediments deposited under exorheic conditions in the so called maluenda and perejiles areas covering 4 4 and 12 km 2 respectively the neogene sedimentary units stratigraphically above the gypsum have subsided due to the karstification of the underlying evaporites the maximum subsidence in both areas has reached at least 200 m the jalon jiloca perejiles alluvial system has been affected by karstic subsidence during its quaternary evolution ten stepped alluvial levels pediment terrace have been identified as a consequence of synsedimentary karstic subsidence the deposit of an alluvial level can be locally thickened changing in a short distance from less than 10 m to more than 100 m in thickness thus the deposit of an individual terrace can be locally superimposed on the deposits of older terraces the palaeokarst recorded in the sediments of the different alluvial levels shows how the karstic subsidence has controlled the dynamics of the sedimentary system the alluvial karstic subsidence is currently active in the flood plains affecting fluvial channels buildings communication ways irrigation ditches and the calatayud gypsum scarp