fault generated mountain fronts in southeast spain geomorphologic assessment of tectonic and seismic activity abstract tectonic activity of se spain is evaluated through the application of a general morphometric analysis over 17 different mountain fronts the selected fronts are distributed along the two most prominent crustal scale structures of the mediterranean sector of spain the eastern betic shear zone ebsz and the valencia trough geomorphic indexes used in this study are mountain front sinuosity index smf and valley floor width ratio vf this work is largely based on the smf vf regression analysis of the studied fronts together with previous available data from sw usa the development of mountain fronts in both different lithologies and tectonic contexts enabled characteristic morphometric signatures for different activity scenarios tectonic activity classes to be obtained this study thus indicates that variations of mountain front geomorphology triggered by different styles of faulting can be detected by morphometric analysis it is demonstrated that discrete uplift rates of 0 15 0 08 m ka are sufficient to keep relatively low smf values down to 1 4 in active fronts class 1 taking into account the reported uplift rates and preliminary palaeoseismic data for some of the class 1 studied fronts recurrence periods for surface rupture events can be theoretically bracketed for se spain recurrence periods for class 1 fronts could theoretically range between 10 000 and 12 500 years for maximum slip conditions and 1750 and 2600 years for minimum slip conditions inactive fronts class 3 develop under uplift rates down to 0 03 m ka and tested recurrence intervals for rupture events range between 25 000 and 50 000 years class 2 fronts of intermediate characteristics and activity display uplift rates between 0 07 and 0 03 m ka

evolution of the lowest amazon basin modeled from the integration of geological and srtm topographic data morphologic features obtained from srtm data integrated with geologic information are emphasized in this paper in order to provide the basis for understanding the development of the lowest amazon drainage basin focusing on the history of one of the largest amazonian tributaries the tocantins river and on the origin of the marajo island throughout the quaternary this approach led to the recognition of a fan morphology related to the record of a tectonically controlled n nw s se orientated paleovalley cut down into miocene and older rocks the incised valley was fed by a paleo tocantins river which deposited its sediment load continuously to the north northwest reaching the marajo island and producing a deposit with a fan morphology during the plio pleistocene pleistocene as characterized in the srtm images this channel system became abandoned due to capture by ne sw orientated faults and establishment of the para river by w e strike slip movements this event which probably took place in the mid holocene was responsible for the detachment of the marajo island from the mainland 2006 published by elsevier b v

late pleistocene alluvial plain sedimentation in lower narmada valley western india palaeoenvironmental implications abstract late pleistocene fluvial sediments that were deposited in a slowly sinking basin are now exposed as 30 50 m high incised vertical cliffs all along the lower narmada valley in western india the exposed fluvial deposits have been classified into two sediment packages alluvial fan sediments overlain by alluvial plain sediments the alluvial plain sequence has not been studied previously it consists mainly of sands and silts and is dominated by overbank deposits occurrence of large scale bedforms in the alluvial plain sequence points to the existence of a large sand bed river in an alluvial plain setting the major sedimentary facies in stratigraphic order include large channel fills giant epsilon cross bedded strata overbank fines occurring in horizontal massive and undulatory stratified forms associated with crevasse splay and backswamp deposits and a reddish brown palaeosol overlain by thinly stratified sands and silts at the top of the exposed sediment succession large sized channel fills occur at two stratigraphic levels which are morphologically similar and are indicative of high rates of deposition and avulsion the large channel fill structures and the giant epsilon cross bedded strata indicate a large single channel river that was consistently 10 15 m deep and about 70 80 m wide even during the dry seasons these dimensions are larger than those of the present day narmada river at low discharge levels the overbank sediments indicate rapid deposition through frequent overbank floods and floodplain aggradation by a laterally shifting river available chronologic data suggests that the reddish brown palaeosol correlates with a regional phase of pedogenesis in the alluvial plain of gujarat prior to the last glacial maximum lgm the thinly stratified sands and silts overlying the palaeosol were deposited by a considerably depleted but perennial river during the arid phase of the last glacial maximum overall the alluvial plain sediments of the lower narmada valley particularly those below the palaeosol have been attributed to a hyper avulsive large river with low sinuosity whose high discharge levels were determined primarily by a large catchment area further to the east and not by the semiarid climate prevailing in the gujarat alluvial plain during the upper part of the late pleistocene the study concludes that the narmada river has maintained a large catchment at least since the last 100 ka however the river was characterised by a much bigger channel during much of the late pleistocene with discharge levels higher than the present day

lack of evidence for enhanced preservation of sedimentary organic matter in the oxygen minimum of the gulf of california a test of the hypothesis that hydrogen rich organic matter accumulates preferentially in sediments under oxygen minima has been carried out by examining the composition of laminated and homogeneous diatomaceous sediments of the guaymas basin in the gulf of california the laminated sediments occur where an intense oxygen minimum intersects the slope around the margins of the basin above and below the depth of the oxygen minimum the sediments are homogenized by a burrowing infauna the two sediment types have very similar bulk chemical and mineral compositions and the organic matter is overwhelmingly marine the total organic carbon contents and rock eval parameters hydrogen and oxygen indices of the two sediment types are not significantly different whereas a road organic carbon maximum in the homogeneous sediments is centered at roughly 1200 m depth on the slope of the basin this maximum lies deeper than the core of the oxygen minimum thus both the concentration and the nature of the organic matter in the sediments of this highly productive marginal marine basin are not related to the concentration of dissolved oxygen in the bottom waters

organic carbon and sedimentation rate further evidence for anoxic deep water conditions in the cenomanian turonian atlantic ocean abstract the relationship between organic carbon content and sedimentation rate based on data derived from recent to miocene sediments deposited under oxic and anoxic sea water conditions is used to characterize the different depositional environments these data are compared with data of cenomanian turonian dsdp sediments from the atlantic ocean the results may support deposition in anoxic environments due to extremely reduced deep water circulation as the main cause for the formation of cenomanian turonian black shales in the north atlantic rather than increased supply of organic matter due to higher oceanic productivity

geomorphic constraints on surface uplift exhumation and plateau growth in the red river region yunnan province china field observations digital elevation model dem data and longitudinal profi le analysis reveal a perched low relief upland landscape in the red river region yunnan province china which correlates to an uplifted regional low relief landscape preserved over the eastern margin of the tibetan plateau as with other major rivers of the plateau margin the red river has deeply incised the lowrelief upland landscape which we interpret to be the remnants of a pre uplift or relict landscape we examine longitudinal river profi les for 97 tributaries of the red river most profi les consist of three segments separated by sharp knickpoints an upper lowgradient channel segment a steeper middle channel segment and a very steep lower channel segment upper channel segments correspond to the relict landscape and have not yet experienced river incision steeper middle and lower segments indicate onset of rapid two phase river incision on the basis of which changes in external forcings such as climate or uplift can be inferred in terms of two end member scenarios two phase incision could be the result of pulsed plateau growth in which relatively slow uplift during the fi rst phase is followed by rapid uplift during the second phase or it could refl ect adjustments of the main channel to changing climate conditions against the backdrop of steady plateau growth reconstruction of the paleo red river indicates 1400 m river incision 1400 1500 m surface uplift and a maximum of 750 m vertical displacement across the northern red river fault elevating the northern ailao shan range above the surrounding relict landscape on the basis of stratigraphic constraints incision along the red river likely began in pliocene time

modeling large scale fluvial erosion in geographic information systems variants of the stream power model have become standard for large scale erosion modeling in geographic information systems gis because they can be applied over broad areas without the need for detailed knowledge of stream characteristics gis based implementations of the shear stress stream power per unit length and stream power per unit area models are closely related to one another and related also to empirical sediment yield models derived from continental scale factor analyses based on a detailed examination of the implementation of stream power analyses at the scale of continental mountain ranges we demonstrate that 1 the careful selection of a digital elevation model dem projection can minimize length and area distortion when analyzing large portions of the earth such as the himalaya or andes in the two dimensional plane of a dem 2 the area discharge proxy frequently employed in gis based stream power studies may not be appropriate for rivers that flow through significant rain shadows or climatic zones 3 decreasing the resolution of a dem from 30 to the 900 m typical for studies of large extent decreased the mean slopes of 15 rivers in the olympic mountains by 65 increased the mean drainage basin size by 14 and caused a 17 reduction in median main stem channel length 4 the coefficients k m and n common to different versions of the stream power law are themselves sensitive to grid resolution when determined from an analysis of area slope plots 5 stream power per unit area decreased in the olympics mountains as grid resolution decreased d 2002 elsevier science b v all rights reserved

morphotectonic segmentation and spatial variability of neotectonic activity along the narmada son fault western india remote sensing and gis analysis abstract morphotectonic analysis of landscape using remote sensing and gis is an effective way of deducing the pattern and spatial variation of neotectonic activity along poorly investigated active faults in this paper we evaluate the neotectonic activity along a part of the seismically active but poorly understood narmada son fault nsf a more than 1000 km long ene wsw trending fault transecting through the central part of the indian plate the nsf in the study area is geomorphologically expressed as an ene wsw trending line of north facing scarps that delimit the rugged mountainous topography of the uplands to the south and the alluvial basin to the north which prominently slope away from the scarps the scarps are developed in the south dipping basaltic flows belonging to the deccan trap formation of the late cretaceous eocene and continue westward into tertiary rocks and further as a paleobank of the narmada river field studies have revealed that the nsf in the study area is divisible into four morphotectonic segments i to iv which is attributed to the tilakwada karjan madhumati and rajpardi faults cutting across the nsf we characterize the neotectonic activity of the segments through dem analysis using geomorphic indices which include the mountain front sinuosity hypsometric curves hypsometric integral asymmetry factor stream length gradient index and channel sinuosity interpretations of morphometric data are well supported by field data both the entire length of the nsf and the cross faults are found to be neotectonically active we demonstrate that segment ii has undergone the highest intensity of neotectonic activity followed by segments iii i and iv this is corroborated by the highest elevation of scarps and the alluvial deposits the deepest incision 40 m depth and steep northward slope of the alluvial plain in segment ii we infer that the nsf is characterized by differential uplift in recent past which agrees with the high angle reverse faulting with oblique slip movements along the cross faults

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

late cenozoic geomorphic evolution in response to inversion evidence from field and gpr studies in kim drainage basin western india abstract this study presents field and ground penetrating radar gpr data for understanding geomorphic evolution of the kim drainage basin in response to tectonic inversion of the narmada ankleshwar block of the cambay rift basin located on the western continental margin of india the narmada ankleshwar block underwent continuous sedimentation up to mio pliocene and subsequently was subjected to compressional inversion four geomorphic surfaces are recognised that formed in response to the varying degrees of tectonic activity related to phases of inversion these are the early pleistocene erosional surface epes late pleistocene depositional surface lpds early holocene erosional surface ehes and the late holocene depositional surface lhds the phases of increased tectonic activity relate to two erosional episodes while two depositional periods relate to waning tectonic activity or quiescent periods we show that the narmada ankleshwar block suffered inversion earlier than other parts of the cambay basin to the north of the nsf localisation of early inversion movements occurred in an area characterised by thinner crust and involved the development of new reverse faults and transformation of the nsf from a normal to a reverse fault gpr studies indicate the reverse nature of the various faults in the kim drainage basin and provide evidence of their late reactivation under compression the study demonstrates that the parts of a large sedimentary basin can undergo inversion at different times depending on the orientation of pre existing crustal discontinuities with respect to the controlling stress trajectories

sedimentary rocks and crustal evolution tectonic setting and secular trends a significant change in the composition of turbidites deposited at active tectonic settings is seen at the archean post archean transition in comparison to post archean active margin turbidites archean greenstone turbidites exhibit more uniform th sc ratios but with a similar average greater hree depletion gd n yb n 2 less eu depletion eu eu mostly 0 85 and an absence of low th u ratios th u 3 these data indicate that differing mantle sources and or conditions of mantle melting existed during the archean and that intracrustally differentiated rocks older cratons or young differentiated arcs were relatively unimportant as provenance components for archean turbidites in contrast some sedimentary rocks preserved in archean platformal sequences of high grade terranes display significant negative eu anomalies similar to the majority of post archean shales indicating that the general process of cratonization including intracrustal differentiation has taken place since at least 3

tectonics and plate tectonics model for the variscan belt of europe abstract a plate tectonics model is presented to explain the tectonometamorphic characteristics of the european variscides after the closing of two oceanic domains by two sided subduction 500 420 ma and obduction 420 380 ma collision of the european and african continental plates occurred we propose that the subsequent complex intracontinental deformation 380 290 ma is the result of a double subduction of the continental lithosphere accompanied by crust mantle decollement this mechanism explains the progressive crustal thickening and migration of the deformation through time from the sutures toward the external parts of the variscan belt accounting for this model and for the relationships between the european variscides and the other paleozoic peri atlantic belts caledonides appalachian mauritanides and morocco we infer the relative positions of africa america and europe between the silurian and the permian

crustal structure along mehmadabad billimora profile in the cambay basin india from deep seismic soundings abstract deep seismic sounding dss investigations were carried out along a 220 km long n s profile from mehmadabad 22 50 n 72 46 e to billimora 20 46 n 72 58 e in the cambay basin india for studying the detailed crustal structure in the region seismic refraction as well as narrow and wide angle reflection travel time data were obtained for various crustal boundaries starting from the sedimentary section down to the moho by continuous profiling analysis of reversed reflection and refraction travel time data has yielded crustal velocity depth functions for the mehmadabad broach and broach navsari sections along the profile which are significantly different from each other the average velocities at depths in the magmadabad broach section have been found to be considerably lower than those in the broach navsari section by about 25 at 5 km 17 at 10 km 7 at 20 km and 2 at the moho depth and even deeper down in the upper mantle the presence of a relatively thicker sedimentary section especially in the jambusar broach area as revealed by the reversed refraction data analysis is responsible for this gross difference in the average velocity functions for the two parts of the profile and the same have therefore been used for obtaining the detailed crustal depth along the profile the cambay basin which is well known to be bounded by step faults on the eastern and western margins is also dissected into seven major crustal blocks in the n s direction from mehmadabad to billimora the various crustal blocks identified are from the north 1 i mehmadabad block 2 ii tarapur block 3 iii petlad katana block 4 iv jambusar broach block 5 v kosamba block 6 vi surat block and 7 vii navsari billimora block these blocks are displaced up or down relative to the adjacent blocks due to movements along the faults bounding them most of the faults have been found to extend quite deep and to affect the moho boundary considerably as is quite evident from the relief of the moho found along the profile further the seismic activity observed in the region during historical as well as modern times suggests that these deep faults may even be currently active the jambusar broach block which is well known as a broad regional syncline with the maximum thickness of cenozoic sediments has been found to be a major graben revealing a maximum crustal thickness of 38 40 km the granitic basement in this graben is also the deepest at 6 0 6 5 km depth towards the north and south of this major graben the moho as well as the granitic basement are found to be at relatively shallower depths in various crustal blocks the boundary velocity at the moho has been found to be 8 1 8 2 km sec whereas at the granitic basement level there seems to be a lateral velocity variation from 5 7 to 6 3 km sec the crustal depth section obtained in the present study reveals a close relationship between the deep and shallow structural features in this region the deccan traps which form the basement of the overlying tertiary sediments over most part of the profile vary in thickness from 1 0 to 1 8 km however the trap surface rises to very shallow depths on the southern part of the profile the boundary velocity in the deccan traps has been found to vary between 4 8 and 5 2 km sec in the anklesvar kosamba area there is also evidence for the presence of a 1 2 km thick layer of mesozoic sediments with a velocity of about 4 0 km sec underlying the 1 1 km thick deccan traps layer

a tectono geomorphological perspective of micro earthquake swarm activity prone areas around bhavnagar and jamnagar in saurashtra western india abstract areas around bhavnagar and jamnagar in eastern and northern parts of saurashtra respectively are identified previously as prone to recurrent earthquake swarm activity sparse seismotectonic studies so far have not revealed any linkage with known faults in bhavnagar area while no structures are known to occur in the area around jamnagar we carried out detailed tectono geomorphic studies with contrasting geomorphic settings with a view to provide an insight into the swarm activity from a geomorphological perspective the study is based on extensive field studies and quantitative geomorphic analysis of landscape and drainage the area around bhavnagar is divisible into two tectono geomorphic domains the e w trending sihor fault zone located to the west of bhavnagar domain i and the terrain to its south which shows undulating landscape controlled by n s trending structural trends domain ii the quadrant in the sw between these two domains consists of southward titled trappean hills which form source area for drainages flowing northward through sihor fault zone and those flowing eastward through domain ii late quaternary possibly holocene tectonic activity along the sihor fault is indicated by the northward tilt of alluvial plain surface knickpoint in rivers and small scale minor faults along the fault zone prominent decrease in depth of fluvial incision away from the fault zone and youthful landscape indicated by drainage basin analysis domain ii comprises the largely erosional pediplain developed over trappean and tertiary rocks to the south of bhavnagar the drainages show an early stage of landscape development due to ongoing tectonic activity the area around jamnagar is dominantly a peneplain formed over subhorizontal trappean lava flows the peneplain is a manifestation of the prolonged period of non erosion and deposition during the cenozoic the rivers show youthful landscape in the central part of the peneplain which includes large knickpoints rapids anomalous river bends steepening of channel gradient and large potholes this ene wsw trending zone of anomalous fluvial geomorphic anomalies points to the existence of a fault or fold in the subsurface the structure appears to be active as indicated by the denser cluster of earthquake swarm along this zone we infer that the generation of earthquake swarm activity comprising low to moderate magnitude shocks is caused by the sheared rocks along the sihor fault near bhavnagar and the ene wsw trending subsurface structure near lalpur which provide avenues for downward percolation of rainwater to deeper levels causing loss the frictional resistance along the weak planes

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

regional variations in tectonic geomorphology along a segmented convergent plate boundary pacific coast of costa rica abstract pacific coastal mountain piedmont landforms of costa rica extend across the tectonic boundary between the forearc and magnetic arc region of an active convergent margin this plate boundary became segmented circa 1 million years ago when the aseismic cocos ridge impinged upon the middle america trench offshore from the southernmost coastal area of costa rica morphometric analyses of 100 mountain fronts and numerous river long profiles radiometric dating and field studies were conducted in two study areas located arcward from the plate boundary where oceanic lithosphere of the cocos plate is being subducted beneath the caribbean plate region i and the partially subducted aseismic ridge is uplifting the plate margin by isostatic and collisional processes region ii values of tectonic geomorphic parameters mountain front sinuosity s percent dissected facets ffd river concavity k are not only different statistically in regions i and ii but are also different in the areas experiencing isostatic and collisional responses to the subducting aseismic ridge in the area experiencing collisional responses mountain fronts developed along ne dipping imbricate thrust and high angle reverse faults step upward and inland from the coast morphometric data along with the divergence of river terrace profiles from the coast piedmont inland toward the mountains indicates higher uplift rates along interior range mountain fronts isostatic uplift in the outer forearc area in region ii produces a distinctly different morphologic and neotectonic style characterized by regional uplift distributed across a number of blocks bounded by normal faults geomorphic analyses indicate a general southward trend of increasing tectonic uplift from region i into region ii where the highest frequency of mountain fronts with low values of s and ffd as well as rivers with the highest values of k occur over the crest of the subducted ridge field and historical seismic data for these regional trends include 1 fault scarps displacing late quaternary fluvial terraces and colluvial soils in areas of collisional responses 2 holocene latest pleistocene marine sediments uplifted tens of meters along normal faults in areas of isostatic response of region ii and 3 more frequent shallow high magnitude earthquakes in region ii this study indicates that spatial variations in the plate tectonic framework can be detected by regional morphometric analyses using techniques applied in extensional and compressional terranes of arid and semiarid regions but not previously applied to forearc systems along convergent plate boundaries in tropical areas

tectonic geomorphology of active folding over buried reverse faults san emigdio mountain front southern san joaquin valley california investigation of the tectonic geomorphology of active folding over buried reverse faults at the san emigdio mountain front southern san joaquin valley california provides insight concerning the tectonic and geomorphic development of mountain fronts produced by active folding and faulting monoclinally flexed gravels with dips as great as 50 and a minimum age of about 65 ka provide evidence of late pleistocene deformation at the active range front studies of the surface folding of alluvial fans and fluvial terraces indicate a holocene vertical deformation rate of 1 9 3 0 m k y at the active range front and 0 8 1 3 m k y 2 km basinward geomorphic evidence also indicates that the locus of active folding and vertical deformation along the northern flank of the san emigdio mountains has migrated and continues to migrate basinward this evidence includes a relict mountain front now within the uplifted block 5 km from the present active mountain front and the existence of recently initiated folds in the active alluvial fan 2 km basinward from the mountain front northward migration of tectonic activity results in the progressive widening of the uplifted block as the location of active folding moves basinward this migration of tectonic activity appears to occur through the onset and subsequent increase of vertical deformation along more northerly folds and faults accompanied by reduction and eventual cessation of activity along the older more southerly structures

dem based morphometry of range front escarpments in attica central greece and its relation to fault slip rates in this paper we apply current geological knowledge on faulting processes to digital processing of digital elevation models dem in order to pinpoint locations of active faults the analysis is based on semiautomatic interpretation of 20 and 60 m dem and their products slope shaded relief in northern eastern attica five normal fault segments were recognized on the 20 m dem all faults strike wnw ese the faults are from west to east thriassion thfs fili fifs afidnai affs avlon avfs and pendeli pefs and range in length from 10 to 20 km all of them show geomorphic evidence for recent activity such as prominent range front escarpments v shaped valleys triangular facets and tilted footwall areas however escarpment morphometry and footwall geometry reveal systematic differences between the bexternalq segments pefs thfs and avfs and the binternalq segments affs and fifs which may be due to mechanical interaction among segments and or preexisting topography in addition transects across all five escarpments show mean scarp slope angles of 22 18f0 78 for both carbonate and metamorphic bedrock the slope angle equation for the external segments shows asymptotic behaviour with increasing height we make an empirical suggestion that slope angle is a function of the long term fault slip rate which ranges between 0 13 and 0 3 mm yr the identified faults may rupture up to magnitude 6 4 6 6 earthquakes the analysis of the 60 m dem shows a difference in fault patterns between western and northern attica which is related to crustal rheology variations d 2004 elsevier b v all rights reserved

how steep are the himalaya characteristics and implications of along strike topographic variations differences in the topography of central nepal and bhutan are characterized by map and profile patterns of elevation slope relief and stream gradients nepal exhibits a narrow hinterland zone of extreme relief steep slopes and channels and deep fluvial dissection and a wide foreland zone of lower relief active shortening on the main frontal thrust occurs far outboard of the steep topography in contrast bhutan has two high relief zones separated by a narrow low relief step in the topographic and river profiles the southern zone has the higher relief rising abruptly from the main frontal thrust to a series of 4000 m peaks whereas the northern zone consists of low relief high elevation plateau like terrain cut by widely spaced steep walled valleys spatial relationships between these geomorphic features and geologic contrasts are used to examine scenarios of tectonic and surface process interactions the observations favor a model of along strike segmentation in which timing differences in the varying balance of uplift and erosion produce spatial differences of topographic and geologic patterns although other interpretations are possible

alpine glacial topography and the rate of rock column uplift a global perspective abstract the present study investigates the influence of alpine glacial erosion on the morphology and relief distribution of mountain regions associated with varying rock column uplift rates we take a global approach and analyse the surface area distribution of all mountain regions affected by glacial erosion between latitudes 60 s and 60 n most surface area in glaciated mountain ranges is concentrated below the modern snowline as predicted by the glacial buzzsaw hypothesis above the modern snowline the analysed mountain regions all exhibit an exponential decay of surface area with height on the basis of this decay the analysed mountain regions fall within three distinct groups primarily reflecting variations in average values of rock column uplift rates mountain ranges affected by rapid rock column uplift display high above snowline relief and large decay lengths whereas inactive orogens have little relief above the modern snowline we find a surprisingly simple relation between hypsometry above the local snowline and regional tectonic activity

the plate tectonic approximation plate nonrigidity diffuse plate boundaries and global plate reconstructions the central assumption of plate tectonics that plate interiors are rigid remains a useful but uncertain approximation strain rates of stable plate interiors are bounded between 10 i12 10 i11 year i1 and 4 10 i10 year i1 the narrowness of all plate boundaries the other main assumption of plate tectonics as originally conceived is contradicted by many observations both in the continents and in the oceans some diffuse plate boundaries in both continents and oceans exceed dimensions of 1000 km on a side diffuse plate boundaries cover 15 of earth s surface the maximum speed of relative plate motion across any one diffuse plate boundary ranges from 2t o 15 mm year which is faster than some upper bounds on intraplate motion across stable plate interiors 2m m year i1 strain rates in diffuse plate boundaries can be as high as 10 i8 year i1 25 times higher than the upper bound on strain rates of stable plate interiors but 600 times lower than the lowest strain rates across typical narrow plate boundaries the poles of rotation of the plates flanking a diffuse oceanic plate boundary tend to be located in the diffuse boundary which is a consequence of the strong coupling across the boundary

age and depositional environment of the draa sfar massive sulfide deposit morocco the draa sfar mineralization consists of two main stratabound orebodies sidi m barek and tazacourt located north and south of the tensift river oued tessift respectively each orebody is comprised by at least two massive sulfide lenses the hosting rocks are predominantly black shales although minor rhyolitic rocks are also present in the footwall to the southern orebody shales rhyolitic volcanic rocks and massive sulfides are all included into the sarhlef series which is recognized as one of the main stratigraphic units of the moroccan variscan meseta hydrothermal activity related with an anomalous thermal gradient together with a high sedimentation rate in a tectonically driven pull apart marine basin favored the accumulation of organic rich mud in the deepest parts of the basin and the sedimentary environment suitable for massive sulfide deposition and preservation this took place by replacement of the hosting unlithified wet mud below the sediment water interface geochemical data suggest a sedimentary environment characterized by oxic water column and anoxic sediment pile with the redox boundary below the sediment water interface the low oxygen availability within the sediment pile inhibited oxidation and pyritization of pyrrhotite biostratigraphic analysis based on the palynological content of the hosting black shales restricts the age of the sulfides to the asbian substage mid mississippian this age is consistent with earlier geochronological constraints

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

along strike variations of morphotectonic features in the western foothills of taiwan tectonic implications based on stream gradient and hypsometric analysis abstract the taiwan mountain belt provides a key example for analyzing the relation between morphology and tectonics in an active compressional environment there is a striking geometrical relationship between the location of salients and reentrants of the mountain belt and the presence of major crustal inhomogeneities such as structural highs in the foreland basin major along strike variations of structural styles occur in range front rock units of the fold thrust belt stream gradient and hypsometric analysis has been carried out to highlight the along strike variations of morphotectonic features and to illustrate the relative activities in different tectonic regimes of the western foothills the normalized stream length gradient index sl index and the hack profile are two of the stream gradient indices that effectively reflect the tectonic uplift in a region de trending and residual analysis of the hypsometric integral hi eliminates the spatial dependency of small drainage basins and the residual hypsometric integral corresponds to differential uplift activity integration of stream gradient indices and hypsometry provides more robust tectonic interpretation five morphotectonic provinces have been identified in the western foothills based on stream gradient indices and hypsometry each province is bounded by a series of n140 e trending transfer fault zones either inherited from the eurasian passive margin and or newly formed in the sedimentary cover in response to the presence of basement highs within the foreland basin the peikang and kuanyin highs the morphotectonic features as well as deformation styles vary within each province a high uplift but low shortening rate typifies the crustal deformation style in the transpressional regime north of the peikang basement high on the contrary a low uplift but high shortening rate characterizes the crustal deformation style in the transtensional regime south of the peikang basement high the higher geomorphic indices suggest that greater tectonic activity occurs in central than in southwestern taiwan this inference is also supported by the coseismic deformation of the 1999 chi chi earthquake

late quaternary geomorphic evolution of the lower narmada valley western india implications for neotectonic activity along the narmada son fault geomorphic data combined with stratigraphic studies provide significant information to constrain timing and amount of fault movement the lower narmada valley lies astride the narmada son fault nsf an important ene wsw trending tectonic element responsible for the current intraplate seismicity being experienced in the central part of the indian plate varying nature and degree of tectonic movements along the nsf during late pleistocene and holocene have produced four geomorphic surfaces in the lower narmada valley the alluvial plain s1 ravine surface s2 a gravelly fan surface s3 and the valley fill terrace surface s4 two major phases of tectonic movements in a compressive stress regime are recorded along the nsf slow synsedimentary subsidence of the basin during late pleistocene due to differential movement followed by inversion of the basin during the holocene marked by differential uplift along the nsf the study suggests that the inversion of the basin is in response to the significant increase in the intensity of compressive stresses in the indian plate mainly during the early holocene the present incisive drainage and recent seismic activity indicate that the compressive stresses continue to accumulate along the nsf due to continued northward movement of the indian plate

tectonic geomorphology of the red rock fault insights into segmentation and landscape evolution of a developing range front normal fault the red rock fault an active normal fault in southwest montana is reevaluated for fault segmentation using a multiproxy approach field characterization of soils coupled with radiocarbon ages in offset hanging wall fans and terraces constrain the rupture history at a number of locations along strike these data are coupled with morphometric analysis of dated alluvial fan deposits and adjacent 2nd and 3rd order footwall drainage basins to further constrain fault kinematics and segmentation morphometric analysis of the big sheep creek catchment which drains a large area of the footwall range provides a control on the spatial extent offault influence on footwall topography three fault segments are recognized by this study compared with the two segments recognized previously data from offset alluvial surfaces were synthesized with hanging wall fan and footwall drainage basin data to demonstrate a southward increase in displacement along the red rock fault since at least the latest pleistocene at a maximum rate of 1 5 mm yr red rock ruptures were mainly confined to segments suggesting a fault behaving as several discrete slip surfaces however simultaneous rupture of adjacent segments during one event indicates some fault zone coalescence a youthful red rock fault is supported by the absence of tectonic influences on footwall topography and is consistent with an eastward progression of normal fault development along the northern arm of the yellowstone hot spot q 2005 elsevier ltd all rights reserved

dissipative intraplate faulting during the 2016 mw 6 2 tottori japan earthquake the 2016 m w 6 2 tottori earthquake occurred on 21 october 2016 and produced thousands of aftershocks here we analyze high resolution relocated seismicity together with source properties of the mainshock to better understand the rupture process and energy budget we use a matched filter algorithm to detect and precisely locate 10 000 previously unidentified aftershocks which delineate a network of sharp subparallel lineations exhibiting significant branching and segmentation seismicity below 8 km depth forms highly localized fault structures subparallel to the mainshock strike shallow seismicity near the main rupture plane forms more diffuse clusters and lineations that often are at a high angle in map view to the mainshock strike an empirical green s function technique is used to derive apparent source time functions for the mainshock which show a large amplitude pulse 2 4 s long we invert the apparent source time functions for a slip distribution and observe a 16 km 2 patch with average slip 3 2 m 93 of the seismic moment is below 8 km depth which is approximately the depth below which the seismicity becomes very localized these observations suggest that the mainshock rupture area was entirely within the lower half of the seismogenic zone the radiated seismic energy is estimated to be 5 7 10 13 j while the static stress drop is estimated to be 18 27 mpa these values yield a radiation efficiency of 5 7 which indicates that the tottori mainshock was extremely dissipative we conclude that this inefficiency in energy radiation is likely a product of the immature intraplate environment and the underlying geometric complexity

tilting neotectonics of the guadiamar drainage basin sw spain the guadiamar river ows from the southern iberian massif to the guadalquivir foreland basin sw spain its drainage basin displays asymmetries in the stream network the arrangement of alluvial terraces and the con guration of the trunk river valley the stream network asymmetry was studied using morphometric measures of transverse topographic sym metry asymmetry factor and drainage basin shape the alluvial terraces were studied through the lithologic logs of more than a hundred boreholes and eld mapping the morphometric methods demonstrate a regional tectonic tilting toward the sse causing both the migration of the guadiamar river toward the east and the migration of the guadiamar tributaries toward the southwest as a consequence of the guadiamar river migration an asymmetric valley developed with a steep eastern margin caused by river dissection and a gentle western margin where the main alluvial deposits are found the ages obtained using the 14c analysis of samples from several alluvial deposits show that the river migration and thus tilting has occurred during the holocene as well as earlier in the quaternary this interpretation revises the guadiamar longitudinal fault assumed by previous studies copyright 2003 john wiley sons ltd

compositions growth mechanisms and temporal relations of hydrothermal sulfide sulfate silica chimneys at the northern cleft segment juan de fuca ridge three active hydrothermal vents forming sulfide mounds and chimneys monolith fountain and pipe organ and more widely distributed inactive chimneys are spatially related to a system of discontinuous fissures and young sheet flow lavas at the northern cleft segment juan de fuca ridge the formation of zoned tubular curich chimneys type i on the monolith sulfide mound is related to focused flow of high temperature to 328 c fluid bulbous chimneys type ii or beehives at the monolith and fountain vents are products of diffuse high temperature to 315 c discharge a broader zone of vigorous mixing between the hydrothermal fluid and seawater results in quench crystallization of anhydrite rich shells columnar zn sulfide rich chimneys with narrow channelways type iii are constructed where focused and relatively low temperature 261 c fluid vents directly from the basalt substrate the bulk chemistry low cu high pb ag and sio2 contents mineralogy pyrite marcasite wurtzite amorphous silica anglesite colloform and filamentous textures and oxygen isotope characteristics of inactive type iv chimneys indicate a low temperature 250 c origin involving diffuse and sluggish flow patterns and conductive cooling seafloor observations and 210pb data indicate that 1 type iv chimneys are products of an earlier period of hydrothermal activity that ended no more than 60 years ago but prior to the sheet flow eruption 2 the high temperature monolith and fountain vents are manifestations of the same heating event shallow emplacement of magma that led to the sheet flow eruption and recent megaplumes and 3 the pipe organ vent is in a very youthful stage of development and chimney deposition postdates the sheet flow eruption

the use of the stream length gradient index in morphotectonic analysis of small catchments a case study from central italy abstract the aim of this work is to test an integrated quantitative geomorphic approach based on stream length gradient index sl index analysis within the small catchment of the tarugo river in the northern marchean apennines central italy the tarugo river basin 92 km 2 wide strikes sw ne across the marchean ridge and the western sector of marchean piedmont the area is characterized by a series of nw se trending ne verging thrust folds affecting the meso cenozoic bedrock that pass upward from dominantly carbonate to dominantly terrigenous rocks the area investigated has been affected since the pliocene by extensional tectonics accompanying a regional uplift decreasing in rate north eastwards in this work the sl index analysis has been integrated with the spatial analysis of the amplitude of relief a r and compared to geological and geomorphological field data results of this work indicate that the sl index is a valid tool to detect the long wavelength structural effect on topography as well as the incipient local response to regional processes i e regional uplift that is often undetectable by other morphotectonic parameters in contrast the sl index analysis seems not be a valid tool for discriminating the local lithological influence from the tectonic one

spatial analysis of stream power using gis slk anomaly maps the stream length gradient index sl shows the variation in stream power along river reaches this index is very sensitive to changes in channel slope thus allowing the evaluation of recent tectonic activity and or rock resistance nevertheless the comparison of sl values from rivers of different length is biased due to the manner in which the index is formulated thus making correlations of sl anomalies along different rivers difficult therefore when undertaking a comparison of sl values of rivers of different lengths a normalization factor must be used the graded river gradient k has already been used in some studies to normalize the sl index in this work we explore the relationships between the graded river gradient k the sl index and the stream power proposing the use of a re named slk index which enables the comparison of variable length rivers as well as the drawing of slk anomaly maps we present here a gis based procedure to generate slk maps and to identify slk anomalies in order to verify the advantages of this methodology we compared an slk map of the ne border of the granada basin with both simple river profile knickpoint identification and with an sl map the results show that the slk map supplies good results with defined anomalies and suitably reflects the main tectonic and lithological features of the study area copyright 2008 john wiley sons ltd

the cr th ratio in precambrian pelites from the kaapvaal craton as an index of craton evolution the cr th ratio in precambrian pelites from the kaapvaal craton in southern africa correlates with pelite th sc and co th ratios and appears to monitor changes in source composition it is a more sensitive indicator of provenance than other commonly used ratios including eu eu la yb and th u pelite cr th ratios are controlled most strongly by the effects of local provenance and local tectonics secular decreases in this ratio the most prominent of which occurred at 2 4 2 3 ga in pelites of the kaapvaal craton record rapid uplift exposing granite decreases in the ratio reflect increases in the abundance of komatiite basalt in sediment sources in response to arc collisions rift hotspot volcanism or intracratonic uplift of older greenstones relatively constant cr th ratios appear to require widespread uplift or and efficient sediment mixing during tectonic stability changes in cr th ratio of kaapvaal pelites reflect a complex tectonic history of the craton from about 3 3 ga to 1 8 ga and do not favor single stage cratonization in the late archean

plio pleistocene transpressional reactivation of paleozoic and paleogene structures in the rhine bresse transform zone northern switzerland and eastern france pliocene to recent uplift and shortening in the southern rhinegraben is documented by deformation of pliocene fluvial gravels deposited on a nearly planar surface as well as by progressive deflection and capture of rivers this deformation is suggested to result from thick skinned tectonic movements as evidenced by ob servations on seismic records which demonstrate a spatial coincidence between en chelon anticlines at the surface and faults located in the crystalline basement these findings contradict the often invoked thin skinned tectonism in the recent tectonic history of the rhine graben in particular the transfer zone between the rhinegraben and the bressegraben is very suitable for reactivation under the present day stress field thick skinned reactivation of faults in the basement is also expressed by focal plane mechanisms of recent earth quakes showing strike slip rather than reverse faulting characteristics this is of importance for the densely populated and industrialised southern rhinegraben pre viously affected by large earthquakes in historical times e g basel 1356

dem and gis analysis of the stream gradient index to evaluate effects of tectonics the normandy intraplate area nw france computer based geomorphometry using a dem digital elevation model allows the analysis of the three dimensional properties of landscape this methodology is particularly useful in an intraplate region like western europe where the simple visual inspection of the topography cannot resolve the evolutionary trends of landforms in these domains the morphologies of the topographic surface may be controlled mainly by climate under a low rate of tectonic deformation among the geomorphometric parameters the stream length index sl has been used to characterize fluvial systems in relation to tectonics movements this work develops an algorithm to derive and map the sl index using a dem and gis to investigate its spatial variations in a broad area the algorithm is applied to a zone of weak intraplate deformation the coastal lowlands of normandy france the obtained spatial distributions of sl point to anomalous zones with high sl values these zones are adjacent to mapped fault scarps and characterized by changes in flow direction a kruskal wallis test shows that the bedrock lithology has no impact on the sl value therefore the sl variations can be related mainly to a differential uplift due to quaternary tectonic forcing quaternary sea level fluctuations may also be responsible for high sl values in a part of the coastal lowland

comparative assessment of three approaches for deriving stream power plots along long profiles in the upper hunter river catchment new south wales australia abstract the downstream distribution of stream power is derived and analysed for 11 different streams in the upper hunter river catchment australia stream long profiles were produced in a gis environment using dem data and catchment area discharge analysis these profiles were analysed using three approaches namely long profile smoothing curve fitting and a theoretical model the methodology for deriving stream power profiles using these three approaches is discussed the long profile smoothing method provides a good approximation of the subcatchment variability in stream power trends the curve fitting method shows that higher order exponential curves provide a better fit for long profile data for the streams of the upper hunter river catchment second order exponential curves fit well with significantly less error the curve fitting method predicts a bimodal upstream and midstream distribution of stream power which is a deviation from our earlier understanding of a single midstream peak the theoretical approach provides a mathematical expression of the observed bimodal stream power distribution the bimodal distribution emphasises the erosion potential of headwater reaches the resultant stream power distribution provides a catchment scale characterisation of the distribution of available energy in any given system using these approaches the variability of stream power in headwater reaches is explained by discharge variability while variability in midstream and downstream reaches is related to high variability in channel gradient

fluvial dissection isostatic uplift and geomorphological evolution of volcanic islands gran canaria canary islands spain abstract digital analysis of torrential gullies barrancos deeply incised into the volcanic island of gran canaria canary islands allows us to extract the longitudinal profiles and pre incision surfaces for individual basins from which morphometric parameters length elevation area slope have been calculated other derived parameters such as ridgeline profiles maximum incision values volume removed by fluvial erosion geophysical relief and isostatic uplift have also been computed based on k ar ages for the island well constrained incision uplift rates have been calculated by means of the combination of different methodological approaches commonly used in orogens and large mountain ranges the geomorphological and morphometric analyses reveal that the island is clearly divided into four environmental quadrants determined by the combination of a couple of key factors the age of the volcanic surfaces and the climatic conditions these factors determine a young sector covered with plio quaternary platform forming lavas finished at 1 9 1 5 ma evolving under contrasting wet ne to dry se climates and an older sector conserving the residual surfaces of the miocene shield building 14 5 8 7 ma at the ridgelines also subjected to wet nw and dry sw climates incision is related to the age zonation of the island maximum incisions

geomorphic analysis of the central range fault the second major active structure of the longitudinal valley suture eastern taiwan numerous landforms along the longitudinal valley suture of eastern taiwan indicate that two opposing reverse faults currently dominate the suturing process between the luzon volcanic arc and the central range of taiwan the east dipping longitudinal valley fault on the eastern flank of the valley is well known the west dipping central range reverse fault on the western flank of the valley is more obscure nonetheless it has produced many uplifted lateritic fluvial terraces along the eastern flank of the central range in the central reach of the valley from just north of the wuhe tableland to near chihshang the fault appears to be active but blind south of chihshang and inactive along the northern part of the longitudinal valley the late quaternary slip rate of the fault is less than 12 8 mm yr this constraint means that the fault is absorbing far less than half of the horizontal shortening across the longitudinal valley suture however the late quaternary slip rate along the fault may be comparable to the uplift and exhumation rate of the central range this suggests that localized brittle slip along the central range fault is an important component of crustal thickening and uplift of the range even though additional shortening and crustal thickening may be occurring because of pervasive deformation beneath the range

subsea floor replacement in volcanic hosted massive sulfide deposits abstract recent research on volcanic hosted massive sulfide vms deposits indicates that syngenetic subsea floor replacement ores form an important component of many deposits in the context of vms deposits subsea floor replacement can be defined as the syn volcanic formation of sulfide minerals within pre existing volcanic or sedimentary deposits by infiltration and precipitation in open spaces fractures inter and intra granular porosity as well as replacement of solid materials there are five criteria for distinguishing subsea floor replacement in massive sulfide deposits 1 mineralized intervals are enclosed within rapidly emplaced volcanic or sedimentary facies lavas intrusions subaqueous mass flow deposits pyroclastic fallout 2 relics of the host facies occur within the mineral deposit 3 replacement fronts occur between the mineral deposit and the host lithofacies 4 the mineral deposit is discordant to bedding and 5 strong hydrothermal alteration continues into the hanging wall without an abrupt break in intensity criteria 1 3 are diagnostic of replacement whereas criteria 4 and 5 may suggest replacement but are not alone diagnostic because clastic sulfide ores contain accessory rock fragments collected by the parent sediment gravity flow s during transport criteria 2 can only be applied to massive semi massive disseminated or vein style deposits and not clastic ores the spectrum of vms deposit types includes deposits that have accumulated largely subsea floor and others in which sedimentation and volcanism were synchronous with hydrothermal activity and precipitation of sulfides occurred at and below the sea floor over the life of the hydrothermal system deposits that formed largely subsea floor are mainly hosted by syn eruptive or post eruptive volcaniclastic facies gravity flow deposits water settled fall autoclastic breccia however some subsea floor replacement vms deposits are hosted by lavas and syn volcanic intrusions sills domes cryptodomes burial of sea floor massive sulfide by lavas or sediment gravity flow deposits can interrupt sea floor mineralization and promote subsea floor replacement and zone refining the distance below the sea floor at which infiltration and replacement took place is rarely well constrained with published estimates ranging from less than 1 to more than 500 m but mainly in the range 10 200 m the upper few tens to hundreds of metres in the volcano sedimentary pile are the favoured position for replacement as clastic facies are wet porous and poorly consolidated in this zone and at greater depths become progressively more compacted dewatered altered and less amenable to large scale infiltration and replacement by hydrothermal fluids furthermore sustained mixing between the upwelling hydrothermal fluid and cold seawater is regarded as a major cause of sulfide precipitation in vms systems and this mixing process generally becomes less effective with increasing depth in the volcanic pile the relative importance of subsea floor replacement in vms systems is related principally to four factors the permeability and porosity patterns of host lithofacies sedimentation rate the relative ease of replacement of host lithofacies especially glassy materials and early formed alteration minerals during hydrothermal attack and physiochemical characteristics of the hydrothermal fluid

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

quaternary evolution of the marrakech high atlas and morphotectonic evidence of activity along the tizi n test fault morocco here we consider the ourika and rheraia drainage basins on the tizi ntest fault zone in the mountains of the marrakech high atlas western morocco with regard to late pleistocene tectonic activity new insights into geomorphological changes in drainage patterns and related landforms are based on geological fieldwork in conjunction with dem analysis lithological and structural data combined with certain geomorphometric indices provide clues to the ongoing uplift of quarternary surfaces in this region five geomorphological indices are utilized 1 drainage network 2 shape of stream long profiles 3 hypsometric integral and curves 4 valley floor width valley height ratio vf index and 5 stream gradient index sl index we also considered the temporal evolution of alluvial deposit complexes with diverse lithofacies such as debris flows channel gravels rockslide debris avalanche stratified slope deposits terrace gravels and fan deposits in the ourika and rheraia valleys pleistocene talus deposits and fluvial sediments are offset by the tizi n test fault in the upper ourika and upper rheraia valleys such deformation of thick continental deposits strongly points to thrust reactivation along the tizi n test fault we define the chronology and overall aggradation phases or lateral incision phases showing how they are the consequences of variations in tectonic uplift and climate as a result we are better able to access recent morphotectonic evolution in part of the marrakech high atlas

geomorphic indicators of active fold growth south mountain oak ridge anticline ventura basin southern california south mountain oak ridge near ventura california is an asymmetric anticlinal uplift forming at the present time above the active buried oak ridge reverse fault shortening along the oak ridge fault accumulated largely in quaternary time and is responsible for the growth and present topography of the westernmost 15 km of the ridge during the past 0 5 m y tectonic geomorphic analysis using several indices of active tectonics provides information concerning fold growth stream gradient indices are relatively high in the northern eroded fold scarp of the ridge a pattern consistent with the existence of active rapid slip on the oak ridge fault mountain front sinuosity along the northern slope of the anticlinal ridge roughly decreases from 2 to 1 toward the westernmost 10 km of observed surface folding valley floor width to valley height ratios along the northern flank of the ridge generally decrease westward from 1 5 to 0 5 values of the hypsometric integral along the northern flank increase significantly from 0 35 to 0 4 maximum 0 55 from east to west drainage density varies from 4 to 6 km km2 along both flanks of the south mountain oak ridge anticline entrenchment of streams into the southern backlimb of the fold along the westernmost 9 km of the structure decreases from 20 m to 1 m from east to west apparent backlimb rotation as measured by dip of strata along the westernmost 7 km of the fold decreases from east to west from 35 to 20 fold growth of the south mountain oak ridge anticline occurred during the past 0 5 ma following deposition of the saugus formation lateral and vertical fold growth were likely produced by westward decrease in fault slip along the buried oak ridge fault

the massive sulphide event in the iberian pyrite belt confirmatory evidence from the sotiel coronada mine well preserved miospore and organic walled microphytoplankton assemblages have been recovered from the black shaly series hosting the massive sulphide deposits of sotiel coronada mine iberian pyrite belt the productive samples yielded miospore assemblages representing the uppermost famennian retispora lepidophyta verrucosisporites nitidus ln miospore biozone of western europe this palynological evidence has important implications for the local geology constraining the commencement of the volcanic activity and corroborating the previously defined local tectonic style moreover at regional scale the new data permit correlation of the black shaly series which hosts the mineralization in all the sulphide deposits hitherto dated in the region reinforcing the hypothesis of an anoxic event occurring in the iberian pyrite belt in the latest devonian times

global time scale and regional stratigraphic reference scales of central and west europe east europe tethys south china and north america as used in the devonian carboniferous permian correlation chart 2003 dcp 2003 the boundaries of the devonian carboniferous and permian stages of the global stratigraphic reference scale abbreviated to global stratigraphic scale gss are described in relation to the biostratigraphic and or lithostratigraphic units of the regional stratigraphic reference scales abbreviated to regional stratigraphic scales rss of central and west europe east europe tethys south china eastern tethys and north america in their type regions the boundaries of gss units rarely coincide with those of homonymous rss units moreover the definitions of some rss units have changed several times over the last decades and subsequent misunderstanding of the stratigraphical significance of these changes has often introduced errors into proposed global correlation charts the stratigraphic framework proposed in our global devonian carboniferous permian correlation chart 2003 dcp 2003 devonian carboniferous permian correlation chart 2003 menning m schneider j w alekseev a s amon e o becker g von bitter p h boardman d r bogoslovskaya m braun a brocke r chernykh v chuvashov b i clayton g dusar m davydov v i dybova jachowicz s forke h c gibling m gilmour e h goretzki j grunt t a hance l heckel p h izokh n g jansen u jin y g jones p kading k ch kerp h kiersnowski h klets a klug ch korn d kossovaya o kotlyar g v kozur h w laveine j p martens th nemyrovska t l nigmadganov a l paech h j peryt t m rohn r roscher m rubidge b schiappa t a schindler e skompski s ueno k utting j vdovenko m v villa e voigt s wahlman g p wardlaw b r warrington g weddige k werneburg r weyer d wilde v winkler prins c f work d m 2004 abschlusskolloquium dfg schwerpunktprogramm 1054 evolution des systems erde wahrend des jungeren palaozoikums im spiegel der sedimentgeochemie abstracts univ erlangen germany 2004 p 43 herein abbreviated to dcp 2003 and cited as dcp 2003 in references is an attempt to reduce these errors the dcp 2003 is the stratigraphic base for project 1054 of the deutsche forschungsgemeinschaft dfg the evolution of the late palaeozoic in the light of sedimentary geochemistry this composite time scale has been carefully balanced as far as data allows to remove unnecessary artificial compression and expansion of time intervals biozonations and depositional events the ages selected in dcp 2003 are markedly different to those in the geologic time scale 1989 gts 1989 harland w b armstrong r l cox a v craig l e smith a g smith d g 1990 a geologic time scale 1989 cambridge univ press cambridge harland w b armstrong r l cox a v craig l e smith a g smith d g 1990 a geologic time scale 1989 cambridge univ press cambridge pp 1 263 and in gradstein and ogg gradstein f m ogg j 1996 a phanerozoic time scale episodes 19 1 2 3 4 insert whereas they are closer to those of the geologic time scale 2004 gts 2004 gradstein f m ogg j g smith a g 2004 a geologic time scale 2004 cambridge univ press cambridge pp 1 589 mostly the ages are rounded to the nearest 0 5 ma in order to avoid estimates of questionable accuracy whereas ages of 0 1 ma in the gts 2004 and their error bars of 0 4 ma to 2 8 ma for the devonian to permian stage boundaries suggest an improved accuracy in contrast in the dcp 2003 questionable ages and positions of stratigraphic boundaries are marked by arrows c 2006 elsevier b v all rights reserved

regional tectonic framework structure and evolution of the western marginal basins of india abstract the kutch saurashtra cambay and narmada basins are pericontinental rift basins in the western margin of the indian craton these basins were formed by rifting along precambrian tectonic trends interplay of three major precambrian tectonic trends of western india dharwar nnw sse aravalli delhi ne sw and satpura ene wsw controlled the tectonic style of the basins the geological history of the basins indicates that these basins were formed by sequential reactivation of primordial faults the kutch basin opened up first in the early jurassic rifting was initiated in late triassic along the delhi trend followed by the cambay basin in the early cretaceous along the dharwar trend and the narmada basin in late cretaceous time along the satpura trend the evolution of the basins took place in four stages these stages are synchronous with the important events in the evolution of the indian sub continent its breakup from gondwanaland in the late triassic early jurassic its northward drifting during the jurassic cretaceous and collision with the asian continent in the early tertiary the most important tectonic events occurred in late cretaceous time the present style of the continental margins of india evolved during early tertiary time the saurashtra arch the extension of the aravalli range across the western continental shelf subsided along the eastern margin fault of the cambay basin during the early cretaceous it formed an extensive depositional platform continuous with the kutch shelf for the accumulation of thick deltaic sediments a part of the saurashtra arch was uplifted as a horst during the main tectonic phase in the late cretaceous the present high thermal regime of the cambay bombay high region is suggestive of a renewed rifting phase

magnetotelluric study to characterize kachchh mainland fault kmf and katrol hill fault khf in the western part of kachchh region of gujarat india abstract the kachchh mainland fault kmf is a major e w trending fault in the kachchh region of gujarat extending 150 km from lakhpat village in the west to the bhachau town in the east the katrol hill fault khf is an e w trending intrabasinal fault located in the central region of kachchh basin and the south of kmf the western parts of both of the faults are characterized and the sediment thickness has been estimated in the region using a magnetotelluric mt survey at 17 sites along a 55 km long north south profile with a site spacing of 2 3 km the analysis reveals that the maximum sediment thickness is 2 3 km quaternary tertiary and mesozoic in the region out of which the mesozoic sediments feature a maximum thickness of 2 km the estimated sediment thickness is found consistent with the thickness suggested by a deep borehole depth approx 2 5 km drilled by oil and natural gas corporation ongc at nirona northern part of the study area from 2 d inversion of the mt data three conductive zones are identified from north to south the first conductive zone is dipping nearly vertical down to 7 8 km depth it becomes north dipping below 8 km depth and is inferred as kmf the second conductive zone is found steeply dipping into the southern limbs near manjal village 28 km south of nirona which is inferred as the khf a vertical dipping down to 20 km depth conductive zone has also been observed near ulat village located 16 km north of manjal village and 12 km south of nirona village this conductive zone becomes listric north dipping beyond 20 km depth it is reported first time by a geophysical survey in the region

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

application of high resolution interferometric dems to geomorphic studies of fault scarps fish lake valley nevada california usa abstract recent developments in interferometric radar remote sensing provide a method for deriving detailed topographic and slope information for fault scarp detection in october 1996 the airborne topsar instrument ieee trans geosci remote sens 30 1992 933 was flown over southwest nevada and east central california topography calculated from topsar data are in the form of a high resolution 5 m spatial grid digital elevation model dem in this study we focus upon the large steep fault scarps that cut alluvium and alluvial fans in fish lake valley east of the white mountains of nevada california a series of topographic profiles extracted from the dem reveal that the larger fault scarps are greater than 40 m in height and that the average midsection slope angle for all measured scarps is approximately 23 these large scarps are the product of multiple offsets rather than a single event other relevant geomorphic features present in the digital topography include splays and benches along the main fault levees cutbanks gullies incising fault scarp slopes shutterridges offset drainage and small normal faults with scarp heights of only 4 6 m field work corroborated general geomorphologic landforms confirmed fault scarp morphometry and aided the evaluation of the accuracy of the dem we are also able to assess fault segmentation models that divide the fish lake valley fault zone flvfz into discrete segments based upon surface rupture characteristics

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

discussion of the article by a c lasaga and h ohmoto on the oxygen geochemical cycle dynamics and stability geochim cosmochim acta 66 361 381 2002

relationship between inferred redox potential of the depositional environment and geochemistry of the upper pennsylvanian missourian stark shale member of the dennis limestone wabaunsee county kansas u s a analyses of 21 samples collected from a core of the 52 8 cm thick stark shale member of the dennis limestone in wabaunsee county kansas demonstrate four cycles with two orders of magnitude variations in contents of cd mo p v and zn and order of magnitude variations in contents of organic carbon cr ni se and u the observed variability in amounts and or ratios of many metals and amounts and compositions of the organic matter appear related to the cause and degree of water column stratification and the resulting absence presence of dissolved o2 or h2s high cd mo u v zn and s contents a high degree of pyritization dop 0 75 0 88 and high high v v ni 0 84 0 89 indicate the presence of h2s in a strongly stratified water column intermediate contents of metals and s intermediate dop 0 67 0 75 and intermediate v v ni 054 0 82 indicate a less strongly stratified anoxic water column whereas low metal contents and low v v ni 0 46 0 60 indicate a weakly stratified dysoxic water column high p contents at the top of the organic matter rich intervals within the stark shale member indicate that phosphate precipitation was enhanced near the boundary between anoxic and dysoxic water compositions relatively abundant terrestrial organic matter in intervals deposited from the more strongly stratified h2s bearing water column indicates a combined halocline thermocline with the fresher near surface water the transport mode for the terrestrial organic matter the predominance of algal organic matter in intervals deposited from a less strongly stratified water column indicates the absence of the halocline and the presence of the more generally established thermocline relatively low amounts of degraded hydrogen poor organic matter characterize intervals deposited in a weakly stratified dysoxic water column the inferred variability in chemistry of the depositional environments may be related to climate variations and or minor changes in sea level during the general phase of deeper water deposition responsible for this widespread shale member

morphotectonic segmentation of an active forearc 37 41 s chile abstract active forearc regions are characterized by seismo and morphotectonic segments that record recurrent seismic activity and subduction related tectonic deformation on different timescales however it is not well known on which timescales morphotectonic forearc segments retain their tectono geomorphic identity how they are related to earthquake rupture zones and what governs their long term evolution the forearc of the active convergent margin of south central chile 37 41 s is located within the rupture zone of the 1960 chile mw 9 6 megathrust earthquake in this region we combine geomorphological sedimentologic and morphometric dem analysis with compiled structural and geophysical data to reconstruct the morphotectonic evolution of the forearc the southern chile forearc comprises three segments nahuelbuta tolten and bueno segments that record a differential structural and geomorphic evolution whereas the tolten segment appears to be quasi stable the other two segments record pronounced ongoing quaternary uplift the nahuelbuta and bueno segments contain the n s oriented coastal cordillera characterized by numerous tectonically controlled drainage anomalies and evidence of sediment rerouting the morphotectonic segmentation appears to have persisted over timescales of 105 to 106 years importantly these segments do not correlate with earthquake rupture zones that exhibit a short term variability over 102 to 103 years thus earthquake rupture zones are transient second order phenomena which do not determine the long term morphotectonic forearc segmentation overall the differential forearc evolution and segmentation is influenced by a complex interplay of inherited upper plate structures and physical properties of the subducting oceanic nazca plate

geomorphic response of coastal streams to low intermediate and high rates of uplift medocino triple junction region northern california analysis of three dimensional morphological properties of 24 coastal drainage basins that have evolved in areas of low 3 m 1 000 yr rates of uplift near the mendocino triple junction mtj coastal northern california identified channel gradients as the best indicator of tectonism in the landscape lower order tributaries best reflect tectonically controlled differences the largest streams examined of third order are able to adjust to most base level change and maintain their profile form whereas lower order streams farther upstream tend to accumulate the effects of net base level fall and have steepest profiles in the areas of highest uplift rates variations in steepness of first order channel gradients indicate that 1 high uplift rates in the wake of the mtj have existed for at least 73 000 yr and 2 differential tilt of the region to the north and south of the current locus of highest uplift rate is occurring in association with regional uplift although first order streams are excellent indicators of areas of both high uplift rates and regional differential tilting they are less useful in distinguishing between areas of low and intermediate uplift rate analysis of the longitudinal profile of the main trunk stream of ten of the 24 drainage basins using the stream gradient index was more useful to categorize broadly the uplift rates and to distinguish between streams in low and intermediate uplift rate areas although the hypotheses tested herein do not identify the exact mechanism off uplift in the mtj region they do indicate that the nature of deformation is most likely regional tilt rather than crustal shortening with localized compressional folding and thrust faulting they also indicate that geomorphic responses trail in the wake of the uplift rate response caused by development of a slab window beneath the north american plate 1 maximum uplift rates occur 9 km south of the northern boundary of the slab window 2 maximum mean first order channel gradient occurs 16 km south of the northern edge of the slab window and 3 maximum drainage basin relief occurs 20 km south of the northern edge of the slab window associated lag times between passage of the southern edge of the subducted gorda plate slab and geomorphic responses are 160 000 yr for maximum uplift rates 290 000 yr for maximum channel gradients and 370 000 yr for maximum relief