calcareous duricrust al qasim province saudi arabia occurrence and origin in al qasim province saudi arabia calcareous pedogenic duricrust overlies the upper permian carbonates and clays of the khuff formation and ranges in thickness from 60 cm to 2 m it consists of white sandy duricrust capped by brown nodular porous duricrust petrographic investigation led to recognition of three lithofacies that show spatial distribution 1 structureless sandy calcareous mudstone 2 brecciated nodular calcareous mudstone and 3 pisolitic calcareous mudstone the diagenetic changes in duricrust are aggrading neomorphism and formation of calcite rims around quartz grains microprobe chemical analysis was performed on the diagenetically altered material the development of the duricrust is controlled by four factors the climate changes the type of underlying rocks source of carbonate and biological effects the repeated changes from semi arid climate with alternating wet and dry seasons are the main controlling factor in generation of duricrust development during humid periods descending water carries the dissolved carbonates downward as bicarbonates whereas dry and interpluvial period the carbonate rich solutions are carried upwards by capillary or evaporation the claystone and sandstone interbeds possibly affect the development of calcareous duricrust more than the sandstones and dolostones because the former have the ability to attach calcium carbonate to form the duricrust the development of calcareous duricrust is mainly attributed to the pleistocene and early holocene alternating humid and arid periods that prevailed over the arabian peninsula during this time

prediction of the behaviour of landslide dams using a geomorphological dimensionless index landslide dams are a common phenomenon they form when a landslide reaches the bottom of a river valley causing a blockage the first effect of such a dam is the infilling of a lake that inundates the areas upstream while the possibility of a sudden dam collapse with a rapid release of the impounded waters poses a higher flood risk to the downstream areas the results of the main inventories carried out to date on landslide dams have been examined to determine criteria for forecasting landslide dam evolution with particular emphasis on the assessment of dam stability not all landslides result in the blockage of a river channel this only occurs with ones that can move a large amount of material with moderate or high velocities in most cases these landslides are triggered by rainfall events or high magnitude earthquakes a relationship also exists between the volume of the displaced material and the landslide dam stability several authors have proposed that landslide dam behaviour can be forecast by defining various geomorphological indexes that result from the combination of variables identifying both the dam and the dammed river channel further developments of this geomorphological approach are presented in this paper by the definition of a dimensionless blockage index starting with an analysis of 84 episodes selected worldwide it proved to be a useful tool for making accurate predictions concerning the fate of a landslide dam copyright 2002 john wiley sons ltd

detached neotectonic stress field in the northern jura mountains switzerland geodetically determined recent elevation changes plio pleistocene uplift history and quarternary fault movements suggest that the folded jura is neotectonically active this concept is supported by measurements of in situ rock stress in this region

comparative tertiary stratigraphy of the rhine graben bresse graben and molasse basin correlation of alpine foreland events abstract comparative tectonostratigraphic analysis of the tertiary middle eocene pliocene of the rhine bresse graben system and the western molasse basin demonstrates the occurrence of eleven correlative sequences crf i xi these show a close relationship between intra basinal tectonics and depositional history their punctuated sediment accumulation can be related to phases of extra alpine taphrogenesis and alpine orogenesis and to coeval eustatic changes in sea level apparent simultaneity in rift and foredeep sequence development structural deformation and global change in sea level suggests a common causal control in which the development of the alps played an important role

the rhinegraben extension subsidence and shoulder uplift abstract we apply a numerical model of the thermal evolution of a continental lithosphere undergoing extensional deformation to the rhinegraben using reasonable parameters the results of computations are in agreement with the present configuration of the rift and of its shoulders as well as with their evolution since the oligocene contrasting evolutions are reconstructed in the northern and southern rhinegraben whereas the northern history is accounted for by a simple model of homogeneous stretching of the lithosphere the history of the southern rhinegraben cannot be explained without introducing two main periods of heterogeneous stretching the results are locally supported by structural analyses of extensional patterns factors of extension average 1 2 in the axial portion of the rhinegraben and 1 15 for the whole rift section suggesting that the total amount of e w extension reaches 6 km

active normal faulting in the upper rhine graben and paleoseismic identification of the 1356 basel earthquake we have identified an active normal fault in the epicentral area of the basel switzerland earthquake of 18 october 1356 the largest historical seismic event in central europe the event of 1356 and two prehistoric events have been characterized on the fault with geomorphological analysis geophysical prospecting and trenching carbon 14 dating indicates that the youngest event occurred in the interval 610 to 1475 a d and may correspond to the 1356 basel earthquake the occurrence of the three earthquakes induced a total of 1 8 meters of vertical displacement in the past 8500 years for a mean uplift rate of 0 21 millimeters per year these successive ruptures on the normal fault indicate the potential for strong ground movements in the basel region and should be taken into account to refine the seismic hazard estimates along the rhine graben

tectonic implications of transpression and transtension upper rhine graben 1 seismic reflection data from the upper rhine graben urg show a series of synclines along the linear eastern boundary faults from north of karlsruhe to the jura mountains similar structures do not characterize the northern segment of the graben the synclinal shape is portrayed by inversion related to transpression on the linear boundary faults coupled with the conserved easterly dip of the sediments farther inside the tilted hanging block the onset of transpression preceded the known early burdigalian unconformity but was also an early miocene event it suggests that the regional compression axis 1 in early miocene had a trend between 315 and 0 the continuous transtension in the northern segment suggests that at no time during the history of the urg was the regional 1 horizontal with a ne sw trend the lack of transpressional structures in the younger plio pleistocene sediments along the entire eastern boundary of the urg suggests a late change in the regional stress field the main eastern boundary faults and synclines north and south of baden baden are all continuous and have the same trend kinematically they form a single graben segment and respond to the regional stress in the same way

simulation of foreland basin stratigraphy using a diffusion model of mountain belt uplift and erosion an example from the central alps switzerland foreland basin stratigraphy can be considered as the result of three interacting processes thrust deformation which builds the tectonic load sedimentary and erosional processes which redistribute that load and the flexural response of the lithosphere the resultant stratigraphy of foreland basins is commonly composed of a small number of shallowing and coarsening upward cycles bounded by regional unconformities to understand the development of these unconformities we present a simple model of these three processes coupling an evolving thrust wedge on a linear elastic plate with erosion and sedimentation defined by the diffusion equation applied to topography our model demonstrates the development of regional unconformities without recourse to either eustasy or complex viscoelastic models for the continental lithosphere the model describes the thrust wedge foreland basin system in terms of four parameters 1 the effective elastic thickness of the foreland plate te 2 the sediment transport coefficient k 3 the thrust wedge advance rate 4 the surface slope of the thrust wedge the model is applied to the oligocene miocene north alpine foreland basin nafb of eastern switzerland the stratigraphy of the nafb can be simplified into two large scale shallowing upward cycles separated by an unconformity at the base of the burdigalian 22 ma geological information is taken from the nafb to estimate suitable values for the parameters listed above assuming a linear elastic lithospheric rheology the te value is estimated at 10 5 km from decompacted sediment columns data to constrain the sequential development of the thrust wedge come from structural geology the early stages 40 24 ma of compression involved a relatively low angle thrust wedge with an advance rate of approximately 2 4 mm yr at about 24 ma the wedge advance slowed down and thickened by underplating crystalline basement of the foreland plate the value for the transport coefficient has been estimated from previous studies prior to attempting to simulate the broad scale geometry of the nafb the role of each parameter was assessed individually the values for te and k are held constant throughout the simulation of the nafb at 7 5 km and 500 m yr respectively the geometry of the base burdigalian unconformity is reproduced by variations in the parameters describing the thrust wedge the surface slope angle of the wedge is increased from 2 5 to 4 over 0 2 m y and the rate of thrust advance is decreased from 2 mm yr to 0 2 mm yr during the thickening event between 24 and 23 8 ma the rejuvenation of the internal parts of the thrust load causes backtilting of the foreland basin sediments and after a time lag erosion of the distal stratigraphy over the forebulge so simulating the base burdigalian unconformity

tectonic implications of faulting styles along a rift margin the boundary between the rhine graben and the vosges mountains 1 seismic reflection data show the effects of the miocene strike slip environment on the boundary between the upper rhine graben urg and the vosges mountains vm the border fault zone exhibits three types of responses to the new nw se directed regional stress regime where it trends n s no new deformation is observed where it trends nne ssw transpression is evident and it develops into a few kilometers wide zone of intense deformation along the ne sw trending southern boundary of vm transpression intensifies with an increase in the perpendicular shortening component and the border fault zone turns into a reverse fault the uplift of the boundary relative to the graben is estimated to be no less than 1000 m near colmar and significantly more along the boundary with the dannemarie basin these estimates and kinematics considerations support the hypothesis that the vosges mountains are mostly a transpressional feature the rhine fault is mapped and suggested to be a lower miocene structure that was formed in response to the change in the regional stress regime

multiple fault reactivations within the intra continental rhine bresse transfer zone la serre horst eastern france abstract thermochronological structural and kinematic analyses demonstrate the influence of late paleozoic basement structures on the localization and evolution of the rhine bresse transfer zone rbtz a central segment of the european cenozoic rift system zircon and apatite fission track data indicate that the paleozoic crystalline basement and its permo triassic cover exposed in the la serre horst experienced a middle jurassic to early cretaceous heating event which was followed by two distinct periods of cooling a first cooling event occurred in the early cretaceous and is probably related to thermal relaxation a second one started at around 38 ma is interpreted to reflect exhumation that was induced by fault reactivation along the late paleozoic burgundy trough system during eocene oligocene rifting and the formation of the rbtz this fault reactivation resulted in a complex fault pattern and local stress field perturbations in the surroundings of the pre existing horst structure substantial extension was achieved by ene wsw striking normal faults that trend highly oblique to the dominant strike of the rhine and bresse graben rifts seismic reflection data show that these major normal faults are typically associated with extensional flexures and oriented parallel to pre existing late paleozoic basement faults of the burgundy trough paleostress analyses yield overall nw se extension during the eo oligocene slightly oblique to the structural trend of the rbtz and additionally local stress field perturbations induced by the reactivation of pre existing faults reactivation of paleozoic structures in the rbtz is of extensional rather than of strike slip character indicating that the rbtz is forming a separate oblique graben segment within the european cenozoic rift system rather than a sinistral strike slip transform zone supposedly connecting rhine and bresse graben structures

seismicity wedge beneath the upper rhine graben due to backwards alpine push abstract the distribution of hypocentres in the upper rhine graben area is re examined and discussed with respect to the present day tectonic framework most earthquakes occur within a n60 striking wedge located on top of a moho dome this wedge is limited by the surface and at depth by a plane which in the south of the dome coincides with the se dipping conrad discontinuity in depth the seismicity shows a normal distribution the maximums of which are located on a surface dipping 6 towards se parallel to the south eastward dipping conrad and moho this surface outcrops along the north western edge of the uplifted crystalline vosges and black forest the main shocks in earthquake swarms in the region often occur in the vicinity of this surface and along pre existing n s to ne sw variscan or tertiary faults and show focal mechanisms of strike slip in contrast part of the aftershocks show focal mechanisms of reverse faulting associated with se nw striking compression the seismic wedge and the north westward rising seismic surface suggest initiation of crustal ramp which starts at the south eastern rim of the conrad dome and which may become a thrust plane if se nw compression continues in the south eastern edge of the graben and above the south eastern ridge of the moho dome where evidences for extension have been found we identify clustering of hypocentres along a surface that strikes n150 parallel to the main compression and dipping towards ne dominant normal faulting mechanisms along this surface suggests initiation of a normal probably listric fault at depth the onset of the future fault plane is located on top of the nw se striking ridge of the lower crust and moho which act as a an indenter in addition to thrusting of the whole wedge towards nw increasing of nw se compression would lead to the formation of a half graben at the place of the present sierentz depression

a new geodynamic interpretation for the south portuguese zone sw iberia and the iberian pyrite belt genesis 1 the south portuguese zone spz constitutes the southernmost segment of the variscan iberian massif it is bounded to the north by the beja acebuches ophiolitic complex and related accretionary wedge to the south lie the iberian pyrite belt ipb and flysch deposits forming the southern extent of the zone structural analysis within the spanish side of the spz supports continuous south propagating deformation evolving from early synmetamorphic thrusting in the internal zone to thin skinned tectonics in the southern external domain the accretion of the spz to the ossa morena zone is also witnessed by the presence of various melanges observed throughout the investigated area part of the melanges observed in the ipb are related to the volcanics and mineralizations setting a key point to understand the ipb mineralizations genesis is to constrain the volcanogenic model one underestimated feature is the large amount of submarine calc alkaline ignimbritic facies implying the presence of caldera structures within the province such correlation between caldera environment and ore deposits strongly suggests that the ipb developed in a continental arc our geodynamic model proposes an early north directed subduction associated with the obduction of the oceanic crust toward the south southward this episode is immediately followed by the development of the accretionary prism while farther south a second subduction zone responsible for the arc setting of the ipb initiates subsequent visean continental collision is associated with the deposit of the south propagating flysch and the present geometry of the spz

seismic characteristics and identification of negative flower structures positive flower structures and positive structural inversion negative and positive flower structures and positive inverted structures imply specific modes of formation and their distinctive characteristics make them important criteria for the identification of certain structural styles a negative flower structure from the andaman sea consists of a shallow synform bounded by upward spreading strands of a wrench fault that have mostly normal separations paralleling monoclines and oblique en echelon normal faults flank the divergent wrench fault a positive flower structure from the ardmore basin oklahoma consists of a shallow antiform displaced by the upward diverging strands of a wrench fault that have mostly reverse separations en echelon folds are present on either side of this convergent wrench fault flower structures may resemble extensional or contractional fault blocks on individual seismic profiles flower structures are identified by their unique internal fault and fold architecture by their association with a straight and throughgoing zone of deformation and by their lack of a consistent sense of separation or regional upthrown side positive structural inversion at the rambutan oil field south sumatra basin has formed a shallow anticlinorium and has partly uplifted the underlying graben deeper fault segments bounding the graben have retained their normal fault profiles but at shallow levels some of these faults have reverse separations similar changes of separation with depth may be produced by strike slip but sets of faults with listric profiles and nearby blocklike trend patterns identify the inversion as a dip slip event where correlation of reflections is uncertain or deep control is unobtainable positive inverted structures may also resemble contrational fault blocks detached normal fault assemblages and certain negative inverted structures

identification of wrench faults using subsurface structural data criteria and pitfalls 1 many structures imaged with reflection seismic can resemble a wrench fault system because of the great structural diversity of strike slip faults and the wide range of contractional and extensional features associated with these faults because of these resemblances numerous faults are misidentified as wrench faults by workers using subsurface structural data credible identification requires combinations of profile and map criteria 1 narrow long straight throughgoing solitary master fault or zone of deformation 2 steep to moderate dip of the master fault at depth 3 offset of the top of basement 4 changes in relative upthrown side separation sense and or fault dip direction at depth or along the strike of the master fault 5 narrow fault slices within the master fault zone that steepen and join at depth negative and positive flower structures 6 different separation sense and orientation of relative upthrown side at these fault slices and 7 coeval en echelon flanking structures the identification should be confirmed with other criteria that refute alternative interpretations the main pitfalls to a reliable identification are not considering alternative structural styles and the misinterpretation of features or patterns that superficially resemble wrench systems the profile geometries of basement involved reverse or normal faults particularly those with structural inversion can resemble the single strand of convergent or divergent wrench faults profile geometries of flower structures can be mimicked by narrow contractional horsts or narrow extensional grabens complexly faulted anticlines or synclines splay faults fault zones intruded by salt or shale and overprinted structures pitfalls in interpreting map relationships are possible when structural patterns combine several tectonic influences are controlled by rock anisotropy or include elements hat are not coeval and if the patterns characteristic of other styles are misinterpreted many erroneous identifications of wrench faults can be eliminated by demonstrating that the investigated fault or feature lacks a straight trace lateral length or throughgoing continuity

structure and tertiary tectonic history of the mulhouse high upper rhine graben block faulting modified by changes in the alpine stress regime 1 the mulhouse high horst is situated in the southernmost upper rhine graben and changes in its tectonic history record the interaction with the adjacent alpine front recently released seismic data show that the mulhouse high consists of the sierentz and the altkirch tilted blocks separated by the ferrette fault zone with a throw of several hundred meters during the eocene early rupelian main rifting phase the mulhouse high was the elevated flank of the dannemarie basin with sedimentation affected by the nearby southern boundary of the rhine graben the miocene jura compression extended into the mulhouse high creating a series of semiparallel buried folds with no evidence for thin skin tectonics the change to a nw se regional compressive stress reactivated the main graben faults as wrench faults it also resulted in transpression on the ne sw trending faults particularly the northern segment of the illfurth fault zone consequently the northern part of the mulhouse high was uplifted strike slip motion along the ferrette fault zone is shown to be small

tertiary tectonics of the dannemarie basin upper rhine graben and regional implications recently released seismic reflection data together with previous seismic and well data are used to describe the development of the dannemarie basin in the sw end of the upper rhine graben the dannemarie basin was formed during the main rifting phase of the upper rhine graben as an asymmetrical graben trending ne sw post rift tectonism shifted the depocenter southward and changed the overall shape of the basin miocene jura compression did not result in the formation of folds as in the adjacent mulhouse horst strike slip faulting was dominant in the post rift period and new faults were created most notably the north trending and transpressional belfort fault the boundary of the dannemarie basin with the vosges mountains is part of a restraining bend which may account for the uplift of the southernmost part of the vosges mountains

plio pleistocene ice volume antarctic climate and the global δ18o record we propose that from 3 to 1 million years ago ice volume changes occurred in both the northern and southern hemispheres each controlled by local summer insolation because earth9s orbital precession is out of phase between hemispheres 23 000 year changes in ice volume in each hemisphere cancel out in globally integrated proxies such as ocean 18 o or sea level leaving the in phase obliquity 41 000 years component of insolation to dominate those records only a modest ice mass change in antarctica is required to effectively cancel out a much larger northern ice volume signal at the mid pleistocene transition we propose that marine based ice sheet margins replaced terrestrial ice margins around the perimeter of east antarctica resulting in a shift to in phase behavior of northern and southern ice sheets as well as the strengthening of 23 000 year cyclicity in the marine 18 o record

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

graben width controlling syn rift sedimentation the palaeogene southern upper rhine graben as an example eocene to early oligocene syn rift deposits of the southern upper rhine graben urg accumulated in restricted environments sedimentation was controlled by local clastic supply from the graben flanks as well as by strong intra basinal variations in accommodation space due to differential tectonic subsidence that in turn led to pronounced lateral variations in depositional environment three large scale cycles of intensified evaporite sedimentation were interrupted by temporary changes towards brackish or freshwater conditions they form three major base level cycles that can be traced throughout the basin each of them representing a stratigraphic sub unit a relatively constant amount of horizontal extension l in the range of 4 5 km has been estimated for the urg from numerous cross sections the width of the rift lf however varies between 35 and more than 60 km resulting in a variable crustal stretching factor between the bounding masterfaults apart from block tilting tectonic subsidence was therefore largely controlled by changes in the initial rift width l0 the along strike variations of the graben width are responsible for the development of a deep trough like evaporite basin potash basin in the narrowest part of the southern urg adjacent to shallow areas in the wider parts of the rift such as the colmar swell in the north and the rhine bresse transfer zone that delimits the urg to the south under a constant amount of extension the along strike variation in rift width is the principal factor controlling depo centre development in extensional basins

new insight in the tectonics of the southern rhine graben jura region using local earthquake seismology 1 a new seismic data set was acquired using a dense temporary network of mobile seismic stations it is combined with existing seismological data for the southern rhine graben the data yielded some new focal mechanisms and allowed for a detailed local earthquake tomography these methods give new insight in the structure of the crust and stress conditions in the area by combining the tomography with the earthquake hypocenter locations and focal mechanisms some of the structures in the p wave velocity model are interpreted as active faults the eastern boundary fault zone of the graben is found to be activated in a left lateral strike slip sense the southern continuation of these faults is formed by variscan structures in the basement a change in orientation of the graben axis between the main graben and its southern end have played a role during the development of the system this difference in orientation caused the development of the dannemarie and allschwil subbasins during a late stage of the opening of the rhine graben this study shows evidence for active faulting in the basement underneath the detachment of the jura mountains these faults which are interpreted as reactivated permo carboniferous troughs coincide with the frontal thrusts of the jura mountains it might be that these structures in the basement have influence on the detachment tectonics in the region

seismic reflection evidence for thick skinned tectonics in the northern jura newly released seismic reflection data from the northern jura mountains and southern rhine graben provide the first high quality subsurface images from this area these throw light on the details of the fault patterns in the area and show that the ferrette and le glaserberg jura structures are largely the result of thrust faulting however the faults differ in their nature from those usually assumed in jura tectonics they are not low angle thrusts converging on a decollement zone in triassic evaporites they appear instead to be high angle faults that cross the entire sedimentary section indicating that thick skinned tectonics prevailed in this part of the jura embryonic jura folds can be seen on the images from the nearby mulhouse horst folds that are not supported by thickened triassic evaporites the existence of recent earthquake activity taken together with the prevalence of thick skinned tectonics suggests that occasional large earthquakes cannot be ruled out in this area

upper rhine graben role of preexisting structures during rift evolution 1 the evolution of the cenozoic upper rhine graben was controlled by a repeatedly changing stress field and the reactivation of a complex set of crustal discontinuities that had come into evidence during permo carboniferous times a comparison of the spatial and temporal thickness distribution of synrift deposits with preexisting fault patterns permits to infer a sequence of distinct basin subsidence phases that can be related to changes in the ambient stress field reactivation of a system of late palaeozoic fault systems outlining troughs and highs controlled the nucleation of initially separated middle and late eocene basins the depocenters of which coincided with a preexisting wsw ene trend during oligocene crustal extension the individual basins coalesced resulting in the development of the ssw nne striking upper rhine graben during the late oligocene chattian change in stress field the upper rhine graben was probably reactivated as a dextral strike slip system with the central graben segment forming a releasing bend during the early miocene aquitanian a major reorientation of the regional stress field is held responsible for the main subsidence phase of the northern parts of the upper rhine graben this is reflected by a counterclockwise rotation and northeastward shift of the depocenter axis and later by the middle miocene uplift and erosion of the southern parts of the upper rhine graben during the plio quaternary the upper rhine graben was reactivated as a sinistral strike slip system with the central graben segment forming a restraining bend

european cenozoic rift system abstract the european cenozoic rift system extends from the coast of the north sea to the mediterranean over a distance of some 1100 km it finds its southern prolongation in the valencia trough and a plio pleistocene volcanic chain crossing the atlas ranges development of this mega rift was paralleled by orogenic activity in the alps and pyrenees major rift domes accompanied by subsidence reversal of their axial grabens developed 20 40 ma after beginning of rifting uplift of the rhenish shield is related to progressive thermal lithospheric thinning the vosges black forest and the massif central domes are probably underlain by asthenoliths emplaced at the crust mantle boundary evolution of this rift system is thought to be governed by the interaction of the eurasian and african plates and by early phases of a plate boundary reorganization that may lead to the break up of the present continent assembly

the evolution of the samaoding paleolandslide river blocking event at the upstream reaches of the jinsha river tibetan plateau abstract a large number of landslides have occurred in the upstream reaches of the jinsha river tibetan plateau due to the intensity of tectonic movement in the area remote sensing and field investigation indicate that one of them the samaoding paleolandslide previously blocked the river various river blocking phenomena are well preserved including the old landslide dam and deposits fluvial sediments and hydrostatic sandy sediment to better understand the evolution of the samaoding landslide the authors carried out thermoluminescence tl dating and numerical simulations the tl analysis shows that the landslide occurred at 10 6 0 5 ka bp discrete element method dem simulation of the landslide based on landform restoration provided results that are consistent with field observations the simulation indicates that the entire landslide process lasted for 80 s and the sliding mass reached a maximum velocity of 64 m s the landslide formed a landslide dam with a length of 1900 m a width of 600 m and a depth of 200 m the simulation results show that the level of the riverbed at that the time of the landslide was at least 25 m higher than it is today on the combined basis of the simulation results and field observations the authors propose explanation that the following valley evolution sequence occurred after river blocking the landslide dam experienced flood overtopping and then was eroded until it had mostly had been transported away by river flow and the river then rapidly incised the bedrock to form the present day landform based on the field investigations the authors summarize the failure mechanism of steep inclined antidip rockslides and found that tectonics play an important role in the formation of landslide dams or trigger of landslides and the failure of landslide dams in an active tectonic environment of tibetan plateau

insight into the structure of the upper rhine graben and its basement from a new compilation of bouguer gravity abstract a compilation of gravity data from the upper rhine graben urg is presented that includes all the main data sources from its german and french parts this data is used to show that the urg consists of at least two arc shaped and asymmetric rift units that tectonically are the basic building blocks of the graben in this sense the urg does not differ from other continental rifts such as the african rifts this division should replace the now classical geomorphologic division of the urg into three segments based on their different trends moreover the gravity suggests that the faults in the central and southern segments are continuous and have the same trend appearing to respond as a single kinematic unit changes in the gravity field in the graben are shown to reflect not only the structure of the graben but also the highly variable composition of the basement in this respect the urg is quite different from some other tertiary continental rifts where possible changes in the composition of the basement are mostly masked in the gravity field by the effect of the overlying low density sediments this characteristic is used to study the extent of some of the main basement units that underlie the graben

plate interactions at the southern end of the rhine graben abstract the southern end of the rhine graben in the basel area originated in the early tertiary as an extensional structure it is the site of a transfer zone that connected the rhine graben with the bresse rhone grabens this transfer zone is located in an area into which a late paleozic trough projects which apparently was reactivated from the beginning of miocene to recent times three distinct phases of slight compression were superimposed on the southern end of the rhine graben the first one in the aquitanian early burdigalian is coeval with the development of the helvetic nappes and the insubric fault zone in the alps the second one in the langhian tortonian interval occurred when the external massifs and an important part of the lombardic fold thrust belt in the southern alps developed and the third pliocene to recent one is contemporaneous with the inactivation of this belt and its incorporation into the foredeep of the northern apennines in the aquitanian the forebulge of the alpine orogen is recognizable as a system of flexures that developed preferably on the margin of the late paleozoic trough the middle late miocene one gave rise to uplift of the black forest vosges domain and a river system flowing from this high to the south in the pliocene to recent one alpine rivers made their appearance flowing first to the west into the rhone system and then as the rhine to the north the pliocene to recent phase seems to be decoupled from the body of the central and southern alps

the variscan tectonic inheritance of the upper rhine graben evidence of reactivations in the lias late eocene oligocene up to the recent processing of gravity and magnetic maps shows that the basement of the upper rhine graben area is characterized by a series of ne sw trending discontinuities and elongated structures identified in outcrops in the vosges black forest and the odenwald mountains they form a 40 km wide n30 40 striking sinistral wrench zone that in the visean shifted the variscan and pre variscan structures by at least 43 km to the ne wrenching was associated with emplacement of several generations of plutonic bodies emplaced in the time range 340 325 ma the sub vertical ne sw trending discontinuities in the basement acted as zones of weakness susceptible to reactivation by subsequent tectonism the first reactivation marked by mineralizations and palaeomagnetic overprinting along ne sw faults of the vosges mountains results from the liassic nw se extension contemporaneous with the break up of pangea the major reactivation occurred during the late eocene n s compression and the early middle oligocene e w extension the ne sw striking basement discontinuities were successively reactivated as sinistral strike slip faults and as oblique normal faults elongated depocenters appear to form in association with reactivated variscan wrench faults some of the recent earthquakes are located on ne sw striking variscan fault zones and show sinistral strike slip focal mechanisms with the same direction suggesting also present reactivation

the 2000 yigong landslide tibetan plateau rockslide dammed lake and outburst flood review remote sensing analysis and process modelling abstract in april 2000 a large scale rock avalanche dammed the yigong zangpo river forming an extensive rockslide dammed lake the impoundment lasted for 62 days before a catastrophic breaching caused a massive outburst flood in the yarlung zangpo tibet and the dihang rivers india that travelled downstream to the main floodplain of the brahmaputra in northeastern india in response to discrepancies in the published literature on the event we present a review and re evaluation of the characteristics of the rock avalanche and associated landslide dammed lake we use digital topographical data srtm 3 and dynamic landslide modelling dan w and dan3d to determine the salient characteristics of the damming landslide and to characterise its behaviour our analysis indicates that the volume of the damming rockslide was ca 115 mm3 including 91 mm3 from the initial rockslope failure bulked during disaggregation to 109 mm3 and 6 mm3 from entrainment during its 10 1 km travel down zhamulong gully the debris travelled with an average velocity of 15 18 m s and resulted in a landslide dam on the yigong river with a minimum height of about 55 m using landsat 7 imagery obtained before during and after impoundment in conjunction with an srtm 3 dem we reproduced the filling of the lake we determine that the landslide dam formed an extensive reservoir with an impounded volume of 2 015 gm3 and a maximum possible lake level of 2264 m asl rounded to 2265 m asl our figures differ from those previously published but are believed to be well constrained verifiable estimates of the volumes of the 2000 yigong events the outburst occurred after an attempt by army personnel to manually dig a spillway over the landslide debris and resulted in the entire volume of the lake draining in about 12 h the outburst flood travelled over 500 km south into india with a recorded rise in river level of 5 5 m at the pasighat gauging station 462 km downstream in terms of historical outburst volumes from rockslide dammed lakes the volume of the 2000 yigong event is only exceeded by that of the 1841 outburst flood from the indus river rockslide dammed lake northern pakistan

age and extent of a giant glacial dammed lake at yarlung tsangpo gorge in the tibetan plateau many glacier dams on major rivers at the southeastern edge of the tibetan plateau had been previously determined through remote sensing and glacier terminal position calculation it was hypothesized that such damming substantially impeded river incision into the plateau interior investigation on the large glacial dammed lake at the entrance of tsangpo gorge is critical for understanding this hypothesis so far the issues such as age lake surface elevation and stages of this dammed lake are still in debate our field survey of lacustrine deposits and loess distribution along the middle yarlung tsangpo river and its tributary nyang river suggested that the lake surface elevation was at about 3180 m asl the 23 quartz optically stimulated luminescence osl and 4 organic ams 14 c ages all fall into the last glacial period 41 13 ka the osl and 14 c ages are in general agreement with each other where applicable there might be only one long damming event because the ages of lacustrine deposits from 2970 to 3100 m asl are similar and every lacustrine section is sustained for a long time the estimated lake surface area was 1089 km 2 and the volume was 170 km 3 which differ from previous estimations which suggested two stage about early holocene and 1 5 ka lakes and the largest lake surface elevation reached 3500 m

the basel 1356 earthquake which fault produced it the 1356 basel earthquake was the strongest event to have shaken nw europe in the last thousand years the peculiar location of this historical event makes it possible to relate it to normal faulting along the edges of the rhine graben as well as to reverse faulting along the jura frontal thrust or to fault reactivation within the hercynian basement alternate hypotheses are discussed and their implications compared taking into account available structural data and results of the morphotectonic study performed in the epicentral area this study combines field observations with the analysis of spot satellite imagery aerial photographs and detailed topography it is concluded that the basel earthquake most probably reactivated a basement fault reverse or wrench fault beneath the shallow depth aseismic detachment that underlies the jura mountains

spatial variations of earthquake occurrence and coseismic deformation in the upper rhine graben central europe abstract seismic activity in the densely populated upper rhine graben urg is an aspect in the public political and industrial decision making process the spatial analysis of magnitude frequency distributions provides valuable information about local seismicity patterns and regional seismic hazard assessment and can be used also as a proxy for coseismic deformation to explore the seismo tectonic setting of the urg we combine five instrumental and one historic earthquake bulletins to obtain for the first time a consistent database for events with local magnitudes m l 2 0 in the whole urg and use it for the determination of magnitude frequencies the data processing results in a dataset with 274 poisson distributed instrumentally recorded earthquakes within the urg between 01 1971 and 02 2012 and 34 historic events since the year 1250 our analysis reveals significant b value variations along the urg that allow us to differentiate four distinct sections i iv with significant differences in earthquake magnitude distributions i basel region in the swiss france german border region b 0 83 ii region between mulhouse and freiburg in the southern urg b 1 42 iii central urg b 0 93 and iv northern urg b 1 06 high b values and thus a relatively low amount of high magnitude events in the freiburg section are possibly a consequence of strongly segmented small scale structures that are not able to accumulate high stresses we use the obtained magnitude frequency distributions and representative source mechanisms for each section to determine coseismic displacement rates a maximum horizontal displacement rate of 41 m a around basel is found whereas only 8 m a are derived for the central and northern urg a comparison with geodetic and geological constraints implies that the coseismic displacement rates cover less than 10 of the overall displacement rates suggesting a high amount of aseismic deformation in the urg

optical dating of landslide dammed lake deposits in the upper yellow river qinghai tibetan plateau china abstract two large landslides dehenglong and suozi blocked the upper yellow river from longyang gorge to liujia gorge on the qinghai tibetan plateau this research is significant because no relevant chronologies for this landslide dammed lake had been reported twelve osl samples were collected from the lacustrine sediments of the landslide dammed lake deposited on both banks of the upper yellow river samples yielded similar ages of ca 80 ka the dehenglong landslide and suozi landslide are thus inferred to be triggered by ca 80 ka tectonic movements

a model of displacement and strain for arc shaped mountain belts applied to the jura arc abstract a plan view geometric model for simple parallel differential displacements is presented as an analogue for models of arcuate mountain belt formation we use the model to predict strain patterns produced by parallel displacement in front of a rigid versus deformable indenter a rigid indenter is simulated by an irregular quadrilateral displaced a constant amount along its hinterland boundary a deformable indenter is simulated by an irregular quadrilateral displaced along a hinterland boundary that is allowed to rotate some simple test cases show that the deformable indenter model leads to a pattern of strain very similar to that encountered in arcuate mountain belts short axes orientations are most deviated from the transport direction along the lateral edges of the model with minimum displacement and shortening and vary across the central domain mirroring strain features with variable orientations from mountain belts such as fold trends and minor deformation features such as horizontal stylolite peaks the rigid indenter model also generates short axes deviated from the transport direction but showing far less variation displacement strain relationships from the jura mountains switzerland and france are quantified based upon a simplified version of the finite displacement field for the jura fold thrust belt of philippe y 1995 rampes laterales et zones de transfer dans le chaines plissees unpublished phd thesis universite de savoie we find that the model short axis orientation pattern is very similar over at least the eastern and central jura to the stylolite patterns from the region whilst the long axes closely match the fold axes trends the model suggests that the jura mountains could have formed as a result of a progressive deformation with uniform transport in a general northwest direction