effects of strength properties of discontinuities on the unstable lower slope in the chiu fen erh shan landslide taiwan abstract the chiu fen erh shan landslide was a huge dip slope avalanche triggered by the devastating chi chi earthquake in central taiwan in 1999 anomalous geomorphic precursors such as ground subsidence and thrust which are signs of slope instability were subsequently observed on the lower slope of the chiu fen erh shan landslide in november 2002 post failure behavior and affected area of the lower part of the landslide must be investigated to provide adequate countermeasures this study presents the results of the post failure behavior simulation of the lower slope of the chiu fen erh shan landslide using discontinuous deformation analysis dda the simulation results show that the surface rocks in the sliding mass move faster and further than the rocks at great depth the angle of internal friction is found to have a great influence on the failure process than does the cohesion the sliding rocks are accumulated in the depression in front of the toe of the landslide except under the conditions of very low internal friction the depression performs as a buffer zone when the lower slope fails

anti plane responses of acceleration by a shallow hill next to an alluvial valley abstract this study proposed a hybrid method combining finite element method fem and a wave function based on the lamb series in conjunction with modified transfinite interpolation for use in examining surface accelerations on a semi elliptical hill subjected to shear horizontal sh waves of various dimensionless frequencies at various incident angles the case topography included a semi elliptical hill of fixed height adjacent to a semi elliptical alluvial valley of variable depth ehav differences in site effects between ehav and a single semi elliptical hill or a semi elliptical alluvial valley were investigated as a function of the modified transmissibility tr variations in tr associated with clearly revealed the resonance frequencies rfs associated with an elevated probability of landslides our simulation results revealed a larger number of rfs form in hills adjacent to av than in isolated hill this study proposes a systematic approach for the analysis of site effects of ehav focusing on the identification of potential landslides due to seismic waves excitation

simulating the failure process of the xinmo landslide using discontinuous deformation analysis abstract the xinmo landslide slope in sichuan china was stable during the intensive wenchuan earthquake in 2008 but failed on june 24 2017 landslide debris buried xinmo village and blocked the songpinggou river at the slope toe this study aims to clarify the post failure behavior of the landslide using two dimensional discontinuous deformation analysis 2d dda the simulation results provide comprehensive information on the initiation and the evolution of the landslide the failure process determined by the dda correlates well with the seismic signal analysis results in addition the location of the calculated rock deposit is similar to that shown by the topographic map after the landslide the maximum rock velocity in the landslide is 65 4 m s therefore the impacts of the high velocity blocks and the buildings in xinmo village must be considered to simulate the burial of xinmo village by rocks and the transport of additional rocks across the songpinggou river this xinmo landslide study demonstrates that the dda accurately simulates the post failure behavior and determines the impact area of a landslide with complicated failure processes and topography

buckling deformations at the 2017 xinmo landslide site and nearby slopes maoxian sichuan china abstract a large catastrophic rock avalanche with a total volume of 18 0 106 m3 occurred at 5 38 am 24th june 2017 at xinmo village maoxian sichuan china resulting in 102 casualties 10 deaths 3 injuries and 89 missing we have been conducting a geological and geomorphological investigation in and around the xinmo landslide site since 2015 and we present our results here including data obtained before and after the landslide event the landslide which had an initial volume of 4 46 106 m3 of its source area was induced by rainfall on a previous landslide scar near the ridge top this initial landslide then struck and remobilized older landslide deposits in the middle and lower parts of the slope which subsequently buried xinmo village at the landslide toe the landslide occurred on a dip slope of triassic calcareous psammitic and pelitic schists the bedding plane which dips downslope to the south with an orientation of n80 w 48 s and high angle ne sw striking joints bounded the landslide source area at its base and sides respectively satellite image analysis and field observations of the slope of the landslide scar before and after the landslide strongly suggest that the beds in the source area had already begun gravitationally deforming e g buckling prior to the 2017 landslide moreover pits on the slip surface were likely the result of the dissolution of calcareous material dissolution probably reduced the rock strength along the bedding plane a rainfall event from the 16th to 24th of june 2017 probably dominated the groundwater drainage and finally triggered the catastrophic rock avalanche in addition to the 2017 landslide the hillslope just to the east of the xinmo landslide exhibits pronounced gravitational slope deformation including a tent like structures and warps induced by buckling this suggests that this slope could also fail like the xinmo rock avalanche during a future rainfall or earthquake event

initiation movement and run out of the giant tsaoling landslide what can we learn from a simple rigid block model and a velocity displacement dependent friction law abstract tsaoling landslide is the largest and best documented landslide among several large landslides induced by the 1999 taiwan chi chi earthquake pliocene sedimentary rocks of about 125 mm 3 in volume slid along very flat bedding planes dipping by 14 with an average speed of 35 40 m s for about 1650 m before hitting the bank of the chinshui river during the landslide detailed analysis of dtms before and after the earthquake using a gis software leads to an accurate determination of the locations of the centroids of landslide mass revealing the horizontal and vertical displacements of the 2524 m and 524 m respectively those displacements and landslide mass give an apparent friction coefficient of 0 21 and the release of the potential energy of 1 6 10 15 j we conducted rotary shear high velocity friction experiments on fault gouge from bedding parallel faults under semi wet conditions and at 3 mpa normal stress corresponding to the overburden pressure of the landslide mass we also compiled reported data on the frictional properties on shale powders and fault gouge from the landslide site under both dry and wet conditions and proposed a velocity displacement dependent friction law that can describe most experimental data newmark analysis of landslide motion with six scenarios for different landslide materials and conditions assuming a simple rigid block sliding and using measured frictional parameters revealed that the landslide did not occur with dry frictional properties and that the landslide occurred at 38 39 s with accumulated displacements of 0 62 m 1 09 m and reached at the river bank at 82 87 s after the generation of chi chi earthquake at its epicenter those timings are consistent with high frequency signals at 32 40 s and at 76 s recorded at a nearby seismic station and with a survivor s witness that the landslide initiated 10 s after he felt strong ground motion possible s wave arrival at 25 2 s slip weakening is essential in initiating the landslide and low friction coefficient 0 08 0 1 allowed high speed of the landslide possible the landslide was caused by a few peaks of northeast oriented strong accelerations of the ground motion frictional work during the sliding of the landslide mass was estimated to be of about 23 of potential energy and the rest of the released energy is likely to have been consumed during the stopping phase of the landslide after hitting the river bank in complex processes such as fragmentation heat dissipation and spreading of the landslide deposits

simulating a mining triggered rock avalanche using dda a case study in nattai north australia abstract this study numerically simulated the failure process of a mining induced landslide at nattai north australia results obtained using discontinuous deformation analysis dda matched the conceptual failure process suggested by local geologists and the observed maximum run out distance the maximum velocity of the sliding rocks exceeded 40 m s computational results showed that the slope with inward sub horizontal bedding planes and sub vertical discontinuities remained stable if the mining induced high principle stresses did not fracture the rocks near the slope toe failure of the rocks near the toe of the slope was a key causal factor in the subsequent landslide this paper presents the first numerical simulation of the post failure behavior of the mining induced landslide at the nattai north site it also represents the first dda simulation to clarify the chain reaction of a mining induced landslide and demonstrate its applicability in such investigations

coalification pattern and thermal modelling of the permo carboniferous saar basin sw germany abstract palaeo heat flow values and thicknesses of eroded permo carboniferous sediments in the saar basin were evaluated using one dimensional thermal modelling techniques thermal burial and erosion histories for 16 wells were calibrated by comparing measured and calculated vitrinite reflectance using the kinetic easy r o algorithm and by comparing measured and calculated temperature data on the basis of 37 wells coalification maps were constructed revealing a syn kinematic coalification pattern thermal maturity of the sediments can only be explained by deep burial and moderate heat flows during time of maximum burial i e in the permo carboniferous calculated heat flow data range between 50 and 75 mw m 2 which implies a crustal thickness between 30 and 40 km during the time of maximum burial these values are in accordance with the geodynamic setting of the basin the influence of the permo carboniferous volcanism on the palaeo temperature distribution was overwhelmed by the subsequent deep burial during permian times between 1800 and 3000 m of permo carboniferous sediments were eroded different sedimentation and erosion histories are characteristic for anticlines and synclines respectively

evolution of the lower saxony basin abstract the lower saxony basin is a 300 km long and 65 km wide late jurassic and early cretaceous trough which parallels the northern margin of the rhenish massif this basin became inverted during the senonian and paleocene the lower saxony basin is the most important oil province of germany past production amounts to 200 10 6 t of oil 1 5 10 9 bbl the lower saxony basin is superimposed on the late carboniferous variscan foredeep basin and the frontal structures of the variscan fold belt during the permian to middle jurassic the area formed part of the northwest european basin differential subsidence of the lower saxony basin was initiated during the late jurassic and persisted till albian time this involved reactivation of permo carboniferous fracture systems by divergent wrenching a major aptian deep seated laccolith is evident in the western part of the lower saxony basin during the senonian and paleocene sinistral convergent wrenching induced uplift of the basin floor and folding of its sedimentary fill the margins of the inverted lower saxony basin are thrust over the adjacent stable platform areas the differential subsidence of the lower saxony basin can be related to a period of major crustal extension in the north sea rift basin inversion coincides with important orogenic events in the alpine system and is thought to have been induced by intra plate compressional stresses

landslide reconstruction using seismic signal characteristics and numerical simulations case study of the 2017 6 24 xinmo landslide abstract landslide modeling based on seismic signal characteristics is an effective method to study landslide evolution the scientific challenge lies in how to systematically characterize and reconstruct the entire landslide evolution process using the recorded seismic data we selected the 2017 6 24 xinmo landslide as a case study empirical mode decomposition emd is used to analyze the seismic signals from 14 seismic stations near the landslide area numerical simulations using two dimensional discrete element methods dem are performed to simulate landslide dynamics using the calculated kinetic energy profile after analyzing the short time fourier transform stft and fast fourier transform fft characteristics of the signal the landslide process is reconstructed and compared with the dem simulation the landslide process is observed to consist of a stationary stage slipping stage transition stage entrainment transportation stage and a deposition stage this is the first study that uses seismic signals to identify a transition stage which is a feature that is difficult to constrain from field survey and analysis alone landslide development and movement in the transition stage are discussed considering the sedimentology of the study area this study provides improved theoretical guidance for the reconstruction and characterization of landslide processes by seismic signals

sph based analysis of the post failure flow behavior for soft and hard interbedded earth slope abstract this study proposed a smoothed particle hydrodynamics sph model that could consider two types of soils with different viscosities to reveal the flow mechanism of a soft and hard interbedded earth slope the flow processes of an actual unstable slope in the lushan hot spring district and the saleshan landslide were simulated and the applicability of proposed sph model was validated by comparing the flow process and the flow velocity with dem results and surveyed data thereafter with a conceptual simulating case for the soft and hard interbedded earth slope materials were divided into two types and eight groups consisting of 64 cases were analyzed with different viscosities according to the variation curves of the run out and the flow velocity with time the flow behavior is controlled by the properties of both the soft layer and hard layer and increasing the viscosity of the hard layer can greatly reduce the run out and the maximum velocity the result provided a basis for the mitigation of possible layered earth slope disasters in engineering geology

volcanic rocks as discriminants in evaluating tectonic versus climatic control on depositional sequences permo carboniferous continental saar nahe basin the third and fourth order sequential arrangement of continental sedimentary strata in the permo carboniferous saar nahe basin preserves a detailed record of contemporaneous faulting and volcanism transgressive lacustrine facies of the upper carboniferous coincide with the stratigraphic position of extrabasinally derived pyroclastic fallout layers and features of synsedimentary tectonism such as unconformities thickness and facies changes across faults and seismogenic deformation structures the tectonic imprint on fourth order cycle initiation is further documented by abrupt vertical facies transitions during lake transgression implying rapid and episodic rather than gradual basin subsidence this interaction becomes much more pronounced within the fluvially dominated lower permian when tectonism controlled both the ascent of large volumes of magma within the basin as well as episodic enlargement of accommodation space and depositional area major extrusive volcanic units are preferentially associated with sequences recording transgression that are only preserved in fault bounded hanging wall traps starved from clastic sediment input it is suggested that the stratigraphic position of pyroclastic fallout within the sequential framework of basins elsewhere provides an important analytical tool for the identification of contemporaneous tectonic events and as such form a discriminant between purely climatically induced milankovitch band cycles versus those involving a tectonic control

inversion tectonics along the western margin of the bohemian massif abstract the block faulted southwestern margin of the bohemian massif is superimposed on a permo carboniferous graben major faults of which became repeatedly reactivated during the mesozoic and cenozoic inversion of sedimentary basins associated with this fault system occurred during the early cretaceous and again during the latest cretaceous early cenozoic

the landslide stage of the hsiaolin catastrophe simulation and validation 1 typhoon morakot struck southern taiwan in the summer of 2009 causing the most severe flooding since the 1950s in the early morning of august 9 rainfall triggered the hsiaolin landslide and the resulting debris avalanche covered the township of hsiaolin village kaohsiung around five hundred people were buried alive reconstruction of the runout of the debris avalanche would increase understanding of the large scale avalanches for future hazard mitigation purposes simulation of the debris avalanche runout can provide valuable information for this purpose a new continuum shallow water model is applied to flow over general topography the coulomb friction law is adopted the friction coefficient is initially determined by high pressure rotary shearing tests and subsequently fine tuned by an iterative procedure to minimize the difference between the simulation and the measurement the friction coefficients measured by laboratory tests are found to be in reasonable agreement with the best fit result of the simulation in addition voellmy rheology is applied but it is found that the role of the fluid viscous drag is insignificant the simulation result in the village area is further corroborated by near surface magnetic surveys these indicate that the northern part of the village is dislocated while the artifact structures of the southern part are buried near their original locations by comparing the landslide front and the flow direction of the simulation we are able to confirm as also described by survivors that the landslide swept the northern part of the village into the cishan river while the southern part was flooded subsequently by the debris from a dam breach about 20 min after the landslide

runout simulation of seismic landslides using discontinuous deformation analysis dda with state dependent shear strength model the reliable numerical simulation of the landslide process contributes to the establishment of evidence based disaster mitigation measures in seismically active zones to achieve this goal a simpl

tidal deposits of the lower cambrian random formation eastern newfoundland facies and paleoenvironments the avalon tectonostratigraphic zone occupies about 25 of the area of insular newfoundland late precambrian development of the avalon terrane is distinctly different than that of other parts of the appalachian orogen and cratonic north america late precambrian volcanism and tectonic instability gave way to deposition of about 2 km of cambrian and lower ordovician dominantly epiclastic sediments on a slowly subsiding relatively stable shelf platform the lower cambrian random formation is part of the platformal sequence and is bounded by regional disconformities over much of the newfoundland avalon zone except around fortune bay where it is underlain by older terrestrial and shallow marine sediments the random formation was deposited during a time of global sea level rise and consists of up to 250 m of shoreline nearshore and open shelf deposits that record macrotidal conditions and periodic storm activity cross bedded quartzarenites occur in units to about 50 m thick one exceptional unit is 110

geological interpretation of dekorp 2 s a deep seismic reflection profile across the saxothuringian and possible implications for the late variscan structural evolution of central europe abstract a 250 km long deep seismic section the first of its kind in west germany s dekorp project is interpreted in terms of late variscan collisional tectonics the structural model used is based on the intracontinental thrust tectonics concept of modern collision orogens the crustal profile across the saxothuringian zone seems to indicate north facing ramps antiformal stacks and culminations within the crystalline basement of the internal mid european variscides that have been only partially overprinted by permo mesozoic crustal stretching

a slope movement in a complex rock formation deformation measurements and dem modelling abstract the case history of a deep seated slope movement in a complex rock formation marly arenaceous formation is analyzed the movement monitored for more than 20 years was recognized after the discovery of intense cracking in the concrete lining of a hydraulic tunnel running across the slope the time history of displacements shows that the ongoing deformation process is essentially a stationary creep phenomenon also influenced by transient variations in pore pressure distribution the shearing zone is mainly formed by tectonized clay gouge and is characterized by a mobilized strength close to residual the slope has been modelled by dem approach as a complex blocky structure defined by several joint sets bedding planes inclined and sub vertical joints different hypotheses about the geometry of the slip surface compatible with field evidences are discussed as well as their influence on the critical friction angle of the slope the type of model adopted for rock mass with continuous or staggered joints influences the pre failure deformation mode but the failure conditions are not as much affected finally the response of dem models to the increase in water level at the toe of the slope and to the rise of the groundwater table inside the slope has been analyzed the results of simplified models without flow calculation and coupled hydro mechanical analyses are compared finding some relevant differences

late orogenic basin evolution in the variscan internides the saar nahe basin southwest germany abstract the late variscan evolution of the saar nahe basin in southwest germany is closely controlled by the kinematics of the hunsruck boundary fault which also separates two main tectonostratigraphic units of the variscides the saar nahe basin comprises a half graben structure which formed due to extensional reactivation of a variscan thrust between the early westphalian and late rotliegend about 8 5 km of alluvial fan fluvial and lacustrine sediments accumulated during the permo carboniferous w e oriented extension was accommodated by a system of nw se trending transfer faults and orthogonal normal faults balanced cross section construction and subsidence analyses suggest a 35 extension of the previously thickened crust in the late stage of the orogeny the subsidence analyses show discontinuous depth dependent extension with laterally varying extension factors in the crust and mantle the offset between syn and post rift depocentres is explained by a mantle stretching zone shifted laterally with respect to the area of maximum crustal extension finally a geodynamic model for the evolution of the saar nahe basin with special reference to the earlier variscan development and the general evolution of permo carboniferous basins in central europe is presented

pore structure characteristics of debris flow source material in the wenchuan earthquake area abstract wide grading loose soils wgls are a special slope deposit that often serve as a source for debris flows in the western mountainous area of china previous research indicated that rainfall infiltration induced the migration of fine particles within soil slopes and lead to the initiation of shallow failure and subsequent debris flows clearly soil pore structure exerts a profound influence on seepage during rainfall infiltration which is closely related to soil permeability and corresponding internal erosion the current understanding of the mechanisms of fine particle migration is limited because of the complexity of wgls micropore structure the challenge lies in how to systematically characterize wgls pore structure so that it provides a foundation for future numerical simulations of fine particle migration induced debris flows in this study the characteristics of wgls pore structure were analyzed quantitatively using scanning electron microscopy the results revealed that wgls predominantly contained micropores and mesopores the pore size distribution exhibited a bimodal nature with one peak occurring at a pore diameter of 12 m and another at 72 m the pore complexity of all samples exceeded 0 75 which indicates a low aspect ratio for each pore the average diameter of the fine particles that migrated was then determined with a laboratory seepage test a preliminary jamming probability analysis based on three dimensional micropore reconstruction and average fine particle diameter indicate that jamming is most prevalent along the slope

landslide seismic signal recognition and mobility for an earthquake induced rockslide in tsaoling taiwan abstract landslide seismic signal processing and the newmark s sliding block analysis are used in this research to analyze the initiation time and mobility of the tsaoling rockslide triggered by the 1999 chi chi earthquake in central taiwan a new technique the time frequency spectrum analysis is employed to identify the rockslide initiation and landing times from four real time seismic records of strong ground motion stations the results suggest that higher frequencies ranging from 30 to 70 hz correspond to the rockslide initiation and sliding process which are opposed to the low signal frequency of earthquake the landslide began at 32 5 s the sliding block sped up at 37 5 s and impacted on the opposite riverbank at 76 s on the seismic time record the mobile scenario of tsaoling rockslide induced by chi chi earthquake is simulated using newmark s sliding block analysis the maximum sliding velocity reaches approximately 75 1 m s despite being a simple conceptual model the newmark s sliding block analysis provides consistent results with the real time seismic signal analysis and details of the rockslide kinematics

facies architecture variations and seismogenic structures in the carboniferous permian saar nahe basin sw germany evidence for extension related transfer fault activity abstract sedimentary and volcanic strata in the late orogenic intermontane saar nahe basin preserve a record of sedimentary responses to motion on contemporaneously active faults studies of such deposits can constrain both concepts for lateral and vertical sedimentary facies development and geometric and kinematic models of intrabasinal extension during carboniferous permian syn rift development the saar nahe basin underwent a marked intrabasinal segmentation generated by the offsets of longitudinal normal faults and dextral oblique strike slip faults which were developed perpendicular to the sw ne basin elongation the latter are interpreted as transtensional transfer faults which compartmentalized the basin into segments of differing structural style bed thickness and facies development the fault zones themselves bound an assemblage of variously sized uplifted and downthrown blocks showing variable magnitudes and senses of displacement their activities are recorded by the contrasting depositional histories of tephrostratigraphically constrained sedimentary units occupying footwall and hanging wall block positions during basin filling the influence of faults on the depositional system is seen in their effect as topographic barriers thus restricting free dispersal and mixing of sediment particular sedimentary facies such as coals and biogenic limestones are confined to the immediate vicinity of the fault zones indicating the isolation of sediment starved areas near downthrown hanging walls other fault generated depressions acted as depositional traps favouring considerable accumulations of basaltic lavas volcaniclastic mass flows and fluvial channel deposits in contrast uplifted footwalls are characterized by the formation of unconformities and pedogenic features the abundance of syn tectonic deformation structures such as sediment filled fissures intraformational breccias series of micro faults clastic dykes and other water escape features within syn rift strata and their distinct spatial linkage to fault zones implies considerable seismically triggered processes associated with faulting the combined occurrence of abrupt variations in facies architecture across faults and seismotectonic structures suggests that the basin subsidence history involved a series of events rather than gradual change

extension and application of discontinuous deformation analysis with a damped contact spring model abstract discontinuous deformation analysis dda is widely used in geological and geotechnical engineering to provide an alternative approach to considering damping effect in dynamic analysis a damped contact spring model is implemented the model assumes that the damping component linear dashpot takes place in joints of dda models the normal and shear damping forces are determined according to the relative velocities of the two contacted points a semi analytical solution is also proposed to calculate damping coefficient from a given damping ratio the viscous damping effect produced by the damped contact spring model is independent to step size the proposed model is incorporated into dda program and then several classic damping dynamic examples are constructed to validate the contact model showing good agreement with analytical solutions after that a seismic spectrum of a recorded ground motion is analyzed to show the contact model is suitable for response spectrum generation finally the donghekou landslide case is studied under different parameters suggesting that the proper consideration of damping is essential to natural hazard analysis

characteristics and runout behaviour of the disastrous 28 august 2017 rock avalanche in nayong guizhou china abstract on 28th august 2017 a disastrous rock avalanche occurred in nayong guizhou china this catastrophic event killed 35 people and destroyed 23 houses in this study the failure process of the avalanche was analyzed using uav video footage and seismic signal recordings obtained for the pre and post failure stages of the landslide to better understand the possible mechanism of the avalanche and its dynamic characteristics a numerical simulation was conducted using a dynamic model dan3d to simulate the runout behaviour of the displaced materials simulated results indicate that the failure process of the nayong rock avalanche lasted approximately 30 s the duration of the failure process is close to that from the uav video footage and seismic signal recordings 35 s the duration of movement during the landslide process is estimated to be approximately 90 s with a maximum velocity of 40 m s the combined frictional voellmy model delivered the most accurate results when simulating this event the selected models and parameters are expected to aid in clarifying the propagation processes of similar rock avalanches and thus improve the accuracy of hazard prediction in mountainous karst areas

simulation of the mechanical behavior of inclined jointed rock masses during tunnel construction using discontinuous deformation analysis dda in this paper the mechanical behavior of inclined jointed rock masses during tunneling is considered such rock masses can be considered as an assembly of discrete blocks with the discontinuities having a significant influence on the mechanical behavior to simulate this situation a discrete numerical analysis method discontinuous deformation analysis dda is applied the dda results show the existence of stress arching in the rock masses during tunneling this stress arching is the primary influence on the stress distribution and surface subsidence in addition the stress arching is affected by the dip angle of the jointed rock masses moreover the dda results are in good agreement with experiments explaining the reason for the asymmetrical vertical stress and surface subsidence obtained in laboratory tests these results suggest that dda can be applied to model the tunneling behavior of complicated discontinuous rock masses

investigation of the hsien du shan rock avalanche caused by typhoon morakot in 2009 at kaohsiung county taiwan abstract the hsien du shan rock avalanche at kaohsiung county taiwan was triggered by heavy rainfall brought by typhoon morakot in 2009 heavy rainfall began on the day of august 6 and continued to the morning of august 9 when the slope failure and landslide occurred in this post event investigation physical mechanical and hydraulic properties of the rocks soils at this large landslide site are evaluated the in situ hydraulic conductivity of the soils at the source area was found to be too low k 1 48 10 6 m s for rainfall to vertically infiltrate to the deep sliding surface which was found to have a maximum depth of 85 6 m the post failure simulations using discontinuous deformation analysis dda suggest that the geometry of the sliding surface governs the failure behavior and two continuous progressing failures likely occurred at the beginning of the hsien du shan rock avalanche slope deformation was observed by the local residents before the hsien du shan rock avalanche occurred as a geomorphologic precursor in addition water accumulation along the sliding surface governs the behavior of the sliding surface therefore in the future an early warning system of a rock avalanche can be developed by simultaneously applying high resolution airborne lidar to detect slope deformation and using geo electric measurements to image the infiltration of surface water to the sliding surface

the evolution of the south hunsruck and taunus borderzone abstract the main fabric development of the south hunsruck and taunus borderzone htb occurred during late variscan homoaxial backfolding of an early variscan stack of thrust sheets in a narrow wsw ene trending zone several hundred kilometres long rotation and uplift of the southern rhenohercynian zone was accompanied by the subsidence of the southward adjacent northernmost parts of the saxothuringian zone and the development of the saar nahe basin during the latest carboniferous changing stress conditions gave rise to the development of normal faults along the htb and an extensive tholeiitic and rhyolitic volcanism contemporaneous uplift of the hunsruck is reflected by coarse elastics in the saar nahe basin subsequently the htb became covered by latest carboniferous early permian and mesozoic sediments cretaceous uplift of the rhenish shield caused their erosion the faultzone separating the rhenohercynian hunsruck and taunus from the permo carboniferous saar nahe basin is characterised by reverse and normal faults conjugate shear indicated by slickensides on steep oblique fracture planes as well as slight folding and small scale thrusting in post variscan sediments may be attributed to compressional foreland deformation reactivating variscan joint fabrics and fault systems timing of these deformations is ambiguous and could partly be related to dextral shear during the cenozoic subsidence of the rhine graben cenozoic sediments of the upper rhine graben overstep the northeastern parts of the htb seismic investigations indicate that the htb is associated with a system of southeast hading listric planes extending beneath the moho occasional dip slip earthquakes occur along these fractures

insights into the catastrophic xinmo rock avalanche in maoxian county china combined effects of historical earthquakes and landslide amplification abstract a large and catastrophic rock avalanche occurred at the xinmo village in the maoxian county of the sichuan province of china on june 24 2017 the avalanche destroyed 64 houses and killed 10 people and 73 people were reported to be missing in this study we focused on the contributions of six historical earthquakes to the collapse of rocks in the source area and the landslide amplification caused by the entrainment of pre existing deposits on the landslide path the historical earthquakes in this area contributed different levels of damage on the source rocks particularly the 1933 diexi earthquake induced a few initial cracks in rocks at the crest of the steep hillslope under the combined time effects of long term weathering and gravity the rock blocks in the source area were detached from the crest along the intersecting cracks and over dip soft layer namely the sliding surface the avalanche was amplified by the entrainment of colluvium on its path the influence of the colluvium on the movement process of the xinmo landslide was modelled by the gpu based parallel discontinuous deformation analysis dda method and the effect of the impact and entrainment in the debris flow was rigorously analysed the results indicate that the impact and entrainment can continuously increase the volume of debris flow and the thickness of the colluvium was established to be in the range of 25 9 33 9 m based on the analysis of the deposit pattern and movement duration of the avalanche there were numerous unstable rocks induced by historical earthquakes at the crests of steep hill slopes in the earthquake stricken area with long term damage caused by environmental factors and gravity the failure of unstable rocks with high potential energy is likely to cause severe disasters the excess pore water pressure likely to be present in the colluvium or deposits during impact and entrainment can considerably reduce the effective stress and degrade friction resistance along the runout path as a result the landslide can be intensively amplified owing to the effect of impact and entrainment under a lower friction resistance

subsidenz und tektonik des saar nahe beckens sw deutschland the saar nahe basin in sw germany is one of the largest permo carboniferous basins in the internal zone of the variscides its evolution is closely related to movements along the hunsruck boundary fault which separates the rhenohercynian and the saxothuringian zones recent deep seismic surveys indicate that the saar nahe basin formed in the hanging wall of a major detachment which soles out at lower crustal levels at about 16 km depth oblique extension along an inverted variscan thrust resulted in the formation of a half graben within more than 8 km of entirely continental strata accumulated the structural style within the basin is characterized by normal faults parallel to the basin axis and orthogonal transfer fault zones balanced cross section construction and subsidence analysis indicate extension of the orogenically thickened lithosphere by 35 subsidence modeling shows discontinuous depth dependent extension with laterally varying extension factors for crust and mantle lithosphere thus the offset between maximum rift and thermal subsidence can be explained by a zone of mantle extension shifted laterally with respect to the zone of maximum crustal extension

landslide evolution assessment based on insar and real time monitoring of a large reactivated landslide wenchuan china abstract the upper minjiang catchment is frequently affected by a significant number of large to giant landslides in one such massive older landslide approximately 2 million m3 of sediment was reactivated threatening the safety of a pylon on the landslide and the safety of the only route that allows high speed travel from wenchuan to maoxian to trace the deformation evolution history and analyze the current deformation of the new landslide we examined sar data since 2007 carried out geological and uav surveys and designed and installed real time monitoring equipment this paper presents the main spatial and temporal characteristics of the landslide we found that the landslide has experienced creep deformation in the past five years and its sensitivity to rainfall the development process of the landslide from the formation of tensile crack at the trailing edge to the gradual pushing forward of the crack propagation was revealed the innovation of this paper is to reveal the whole process of the spatial temporal evolution from its beginning to large deformation of a real case of creep landslide which can provide a very good reference for the analysis and monitoring of such creeping landslide evolution process this representative case also shows how to combine remote sensing and in situ monitoring methods to carry out continuous monitoring and the establishment of a warning system for potential landslide sites so as to trace the evolution history derive activity maps and analyze development trend which can significantly reduce landslide risk additional mitigation procedures can be put into place if continuous monitoring of the minjiang river canyon occurs resulting in a reduction of direct losses in particular modeling of the slope deformation and failure damming process and prospective flooding can be done in advance therefore it is expected that this report can strengthen the case for the deployment of systematic monitoring of potential landslide sites by integrating earth observation methods and in situ monitoring systems as an approach to reduce risk

biomarker composition of higher plant macrofossils from late palaeozoic sediments the main objective of the present study was to clarify if the fernane derivatives 5 methyl 10 4 methylpentyl des a 25 norferna 5 7 9 triene math 25 norferna 5 7 9 triene maph 24 25 dinorferna 1 3 5 7 9 pentaene daph 1 and iso 25 norferna 1 3 5 7 9 pentaene daph 2 can securely be assigned to one of the three previously proposed source plant groups from some euramerican upper carboniferous coals uppermost westphalian and stephanian for this purpose remains of conifers cordaites and pteridosperms were isolated from core and outcrop material from different euramerican coal basins e g saar nahe basin blanzy montceau basin results show that math maph daph 1 and daph 2 were present in all extracts of cordaite remains in the sediments surrounding the cordaite macrofossils the compounds were either not detectable or have been found only in comparatively small amounts obviously due to impregnation originating from imbedded cordaites contrarily the compounds were not detected in the extractable organic matter of conifer macrofossils derived from the saar nahe basin from bletterbach south tyrole italy and from frankenberg hessen germany the same is true for remains of horsetails calamites giant club mosses lepidodendron and sigillaria and ferns pecopteris from the saar nahe basin which have been studied for comparison the compounds were also lacking in the extractable organic matter of pteridosperms like alethopteris dicroidium lescuropteris macroneuropteris and neuropteris but were detected in minor amounts in some odontopteris remains from the blanzy montceau basin france however the sediments surrounding the odontopteris macrofossils yielded even higher concentrations of the compounds for this reason the odontopteris macrofossils were most likely impregnated by migrating fernane derivatives from the sediment which were possibly originally originating from cordaite remains therefore cordaites can most probably be considered as one and possibly the only biological source of the precursor molecules of the fernane derivatives math maph daph 1 and daph 2 in the upper carboniferous coal basins

effects of entrainment phenomenon on the rapid and long runout movement of landslides in wenjia gully sichuan china as a common phenomenon in landslides entrainment of loose bed material along the sliding path can enhance both the volume and mobility of the sliding mass posing a great threat to the life and property safety of people in the affected area for the purpose of revealing the mechanism of entrainment phenomenon of sliding material in the runout process a dynamic slice based model was firstly proposed in the present study in this model the motion of landslide body is assumed to follow the rheological law proposed by voellmy additionally through voellmy model the increase in kinetic energy mass and volume of landslide body and entrainment depth caused by the entrainment phenomenon were taken into consideration subsequently on the basis of the dynamic slice based model back analyses were performed on the wenjia gully landslide the effect of entrainment phenomenon on the post failure motion was analyzed the calculated results shows that the travel distance obtained from proposed model is closer to field data than that resulted from scheidegger s empirical method moreover the peak value of the maximum velocity calculated by this model is in good agreement with that get from the dynamic analysis model dan3d when considering the entrainment phenomenon the volume of sliding mass increases greatly in post failure motion this paper provides a new method for analyzing the entrainment phenomenon in landslide motion

crustal scale balanced cross sections through the variscan fold belt germany the central egt segment abstract this paper presents crustal scale geometrically and isostatically balanced cross sections through the rhenohercynian and saxothuringian zones of the variscan fold belt of germany the cross sections are based on surface geological data and on results of the dekorp deep reflection profiles they were constructed by means of computer assisted iterative forward modelling the rhenohercynian zone corresponding to the externides of the variscan belt developed out of a some 300 km wide rifted continental margin sedimentary prism limited to the south by the narrow giessen oceanic basin during carboniferous imbrication this shelf sequence is stripped of its basement above one or more decollements and shortened by some 150 km closure of the giessen ocean and emplacement of the ophiolite bearing giessen nappe entailed a minimum additional 200 km of crustal shortening the structure of the model correlates well with the present outcrop pattern of rock units their metamorphic history the seismic and magnetotelluric architecture of the crust and its present regional distribution of thickness the deeper crust beneath the rhenish massif is probably devoid of extremely weak decollement horizons and pronounced rheological stratification in the southward adjacent saxothuringian zone nappe development involving the stacking of crustal slices during middle devonian to visean times accounts for a further 170 km of crustal shortening above an infracrustal partly blind thrust system with flat ramp geometry total crustal shortening in the analyzed profiles is estimated to be of the order of 520 km this figure is a conservative value prominent uncertainties include the unknown importance of crustal wrenching the state of strain within thrust units the distribution of strain within the lower crust and major changes in thrusting directions during the course of orogenic history

correlation of the rhenohercynian variscides recent structural and stratigraphical data from the rhenohercynian variscides of belgium germany and south cornwall indicate tectonic continuity within this zone prior to disruption along a late carboniferous dextral transcurrent fault this extends from the bristol channel to the vosges parallel to similar lineaments of variscan age in europe and north america consequently a tectonic model for south cornwall is extrapolated to europe and a plate tectonic setting for the evolution of the north european variscides by the closure of an oceanic basin is discussed

simulating the xinmo landslide runout considering entrainment effect this paper investigates the setting causes and main dynamic characteristics of the landslide that occurred at xinmo village diexi sichuan province china on june 24 2017 by comparing the pre and post sliding dems the landslide involved the failure of 3 0 106 m3 rock mass from its source area and had a final volume of 6 3 106 m3 the landslide runout extended 2800 m horizontally and 1200 m vertically and covered an area of 143 1 104 m2 field investigation indicates that entrainment was one of the major causes of the increase in volume of landslide to reproduce the behavior of the landslide runout a depth averaged continuum model that takes entrainment into consideration is applied the simulated results generally agree well with the characteristics of the sliding path and distribution of the landslide deposit as observed in the field it is demonstrated that entrainment plays a significant role in landslide mobility and volume the final volume of the landslide is calculated about 6 21 106 m3 which has more than double its initial volume

compression and right lateral strike slip movement at the southern hunsruck borderfault southwest germany abstract compressional tectonic structures have been known from the southern hunsruck borderzone since the end of the last century in the western part of the borderzone the saar nahe syncline is upthrown whereas in the eastern part the hunsruck is upthrown against the saar nahe syncline folds with axes parallel and oblique to the 60 trending fault zone have been described in the past in the area between idar oberstein and kirn permian lava sheets are displaced in such a way that their recent distribution can be explained by a right lateral strike slip movement of 5 8 km the block of the saar nahe basin between the southern hunsruck borderfault and the saarbrucken anticline has been tilted to the ene since the late palaeozoic the transcurrent movement can only be related to the opening of the upper rhine graben ne sw and nne ssw trending folds in the rotliegend sediments are considered to be transpression structures related to strike slip movement in early tertiary times recent seismicity along the southern hunsruck borderzone indicates that this zone is still active

effects of new baffles system under the impact of rock avalanches abstract to reduce the flow energy of rockfall in rmountain area a baffle array is set up in the protection zone the optimized design can enhance the efficiency of hazard source energy dissipation project in the present study the arc shaped baffles were studied as compared with the conventional baffles square baffles and cylindrical baffles based on practical engineering the comparison of three types of baffles was discussed in detail by experimental studies which primarily focused on the blocking ability and effectivity in particular by determining the optimal case using those different types of baffles the effects of the optimization of baffle system column spacing row spacing and ld distance between first baffle row and chute terminal were investigated according to the results the arc shaped baffle is the best case among those three types of baffle i e the deposit area and runout are all shorter than those of any other cases with the same value of sr shape changing cylindrical to arc shaped will up regulate the fragment blockage degree the following avalanches will take place close to the avalanche deposition leading to a huge dissipation of kinetic energy moreover by comparing deposition dimensionless velocity u and velocity reduction ratio vrr arc shaped baffle system showed competitive blocking ability when sc 3 5 and sr 4 5 with the rise in the ld the energy dissipation efficiency can be enhanced through the particle collision and particle friction during the geo disaster movement furthermore it can effectively narrow the deposit area and reduce deposit depth and deposit width the results obtained from this study are useful for facilitating design of baffles against rock avalanches

new 40ar 39ar ages and geochemistry of late carboniferous early permian lamprophyres and related volcanic rocks in the saxothuringian zone of the variscan orogen germany

the permo carboniferous saar nahe basin south west germany and north east france basin formation and deformation in a strike slip regime the permo carboniferous saar nahe basin in south west germany and north east france formed at the boundary between the rhenohercynian and saxothuringian zones within the variscan orogen where non marine sediments were deposited in a narrow structurally controlled basin the basin has an asymmetrical geometry perpendicular to the south hunsruck fault however there is a lack of growth of the sediment pile into the fault and isopach maps show the depocentre always located adjacent to the south hunsruck fault but migrating towards the north east with time this pattern is typical of a strike slip basin indicating that the south hunsruck fault was a dextral strike slip fault during sedimentation tectonic subsidence curves indicate that during the middle devonian to early carboniferous the basin subsided due to thermal relaxation of the lithosphere a change to very rapid subsidence at the start of the westphalian continued until late in the autunian this was due to mechanical subsidence associated with strike slip movement on the south hunsruck fault towards the end of subsidence in the saar nahe basin the grenzlager volcanics introduced a thermal pulse into the crust leading to thermal cooling and relaxation of the lithosphere

response of a landslide to reservoir impoundment in model tests abstract landslides are often induced or activated by reservoir impoundment within the reservoir area in this paper a physical model test was conducted and compared with another published test to investigate the deformation characteristics and failure behavior of a colluvial landslide for conditions with and without reservoir impoundment the laboratory landslide model represented the lower part of a landslide in the three gorges reservoir area a thrust load was applied to represent the upper part of the landslide the thrust load surface deformation pore water pressure and soil pressure were recorded during the experiments the results show that the effect of the reservoir impoundment reduces the time to failure of the landslide and the load causing the failure as expected when water submerged the lower part of the landslide the shearing resistance was reduced the slip surfaces and failure behavior of the landslide under the two conditions are different the entire landslide mass slid along the contact between the colluvium and the bedrock under reservoir impoundment however without a reservoir the landslide slides partially along this contact and multiple slip surfaces through the colluvium

lower rotliegend fluvio lacustrine sequences in the saar nahe basin the rotliegend beds of the middle of the kusel group to the middle of the lebach group in the saar nahe basin are characterized by sedimentary sequences which developed in streams deltas and lakes

the tsaoling landslide triggered by the chi chi earthquake taiwan insights from a discrete element simulation article i nfo in the village of tsaoling in yunlin county taiwan a major landslide was triggered by the chi chi earthquake in 1999 with more than 125 10 6 m 3 of rock displaced the kinematic behaviour of this landslide is simulated using a 2d discrete element model pfc2d code our numerical model is composed of discs bonded together the initial boundary conditions are applied along the ball wall contacts by using derived velocities integrated from the strong motion data with a duration of 160 s including the peak acceleration near tsaoling the constraints are mainly issued from the final geometry of the landslide including its capacity to cross the river valley and reach a significant elevation on the opposite mountain flank they also result from a variety of geological and hydrological observations including the local levels of material disruption and the location of survivors our modelling thus indicates that a low friction coefficient about 0 15 and a medium strength are required to account for the actual landslide characteristics a self lubrication mechanism probably accounts for the low residual friction our model also suggests that the maximum velocity of sliding reached 50 m s a result that cannot be checked in the absence of actual measurements in addition to friction the strength of sliding block is of special importance because it controlled the possibility for the upper layer fragments to roll and get buried and hence the probability of survival

the variscan belt in central europe main structures geodynamic implications open questions abstract the variscan belt of europe originated from the confrontation of northern europe and gondwana with intervening pre variscan blocks cadomian and older armorica tepla barrandean moravo silesian though a strike slip component cannot be excluded geological evidence suggests a subduction collision process newly discovered features include basaltic rocks with morb affinities high pressure metamorphic rocks trench deposits and large scale allochthonism which also affects the pre variscan basement and has often led to an inversion of the metamorphic isogrades large scale thrusting is evident at all crustal levels and is also observable by geophysical methods the structure of the variscan crust is best described as horizontal tectonic layering late ordovician through carboniferous convergence closed one rhenohercynian and one saxo thuringian basin to the north and at least one mediterranean basin to the south of the pre variscan blocks subduction occurred from the north as well as from the south down under the dorsal core region the exact timing and the driving mechanism of this bilateral activity remains a problem likewise uncertain are the exact limination of the pre variscan blocks and the existence and width of oceanic areas in the saxothuringian zone and in the south facing part of the moldanubian zone there is good evidence of early palaeozoic rifting and of late ordovician through carboniferous plate convergence palaeomagnetic and palaeoclimatic constraints however suggest only a limited extent of oceanic basins in these areas while they appear to allow a wider ocean at the rhenohercynian saxothuringian boundary which is relatively unobtrusive from the geological point of view research during the past decade has produced a wealth of information on the variscan fold belt in europe the resulting geodynamic models however are extremely diverging evidently it is not the time yet for definitive statements the present paper intends to review the state of knowledge to deduce such basic items of a geodynamic model as appear reasonably well documented and to point out the most urgent open questions stress will be laid on central europe which offers a complete cross section through the northern flank of the variscan belt and where we have carried out most of our studies during the last years

analysis and modeling of the combined effects of hydrological factors on a reservoir bank slope in the three gorges reservoir area china abstract more than 5000 landslides have been identified in the three gorges reservoir tgr area since the impoundment in 2003 which posed great threats to the residential houses transportation on the yangtze and dam stability this paper focuses on the evaluation of the coupled influence of rainfall and reservoir water on deformation characteristics and failure evolution of the outang landslide in china based on field investigations a statistical pearson cross correlation coefficient analysis multi technique monitoring data and a numerical model this instability is a reactivated ancient landslide with a volume of approximately 90 mm3 located in the three gorges reservoir the slope behavior is featured with a short period of fast displacement and a relatively long period of semi constant displacement rates per hydrological year and displacements velocities quicken gradually upslope rainfall and reservoir water level are the main triggering factors of slope movement existing in the upper and the lower parts of the landslide respectively based on the numerical results the failure evolution of this landslide is a compounded push retrogression type failure process involving a a first rupture at the toe caused by the reservoir water level that will rapidly mobilize a second and subsequent collapses upwards retrogression type and b the rock mass at the upper part will be pushed out and failed downslope push type due to precipitation these results provide a comprehensive analysis of the outang landslide which is critical for its management as well as for disaster prevention and mitigation of analogous reservoir induced landslides

permian climate development in the northern peri tethys area the lodeve basin french massif central compared in a european and global context abstract the lodeve basin which contains an exceptional long and nearly uninterrupted profile of early to late permian continental red beds is well correlated to the other european permocarboniferous basins together they cover the time span from the late pennsylvanian to the permian triassic boundary although these basins were placed within the equatorial belt for the whole permian several climatic changes are recorded in the sediments terrestrial sedimentation is governed by the interaction of climate and tectonics as well as by volcanism to a variable degree therefore small scale climatic variations of the milankovitch band are hardly discernable and if so they could not be correlated between different basins indeed larger scale climatic shifts could be identified it is shown that the shift from the carboniferous icehouse to the mesozoic warmhouse was a multi stage process this global warming resulted in a general aridisation of northern pangea indicated by outspreading playa and sabkha red beds aeolianites and evaporites several short phases of increased humidity interrupted this trend indicated by wet red beds lake sediments and coal deposits in central and southern europe these wet periods are traceable within the late stephanian lower rotliegend gzhelian asselian topmost lower rotliegend asselian sakmarian upper rotliegend i late artinskian early kungurian and upper rotliegend ii zechstein wuchiapingian the aridisation of the northern pangea which accelerated near the sakmarian artinskian transition is attributed to a reorganisation of the major ocean currents cold water currents along the western flank of the pangea indicated by the permian chert event blocks moisture transport from west onto the continent during roadian and wordian the onset of an additional cold water current along the cimmerian continents blocks moisture transport from the east both phenomena together are responsible for the maximum of aridity at the early to middle permian transition additionally the equatorial climate has been affected by an increasing seasonality within the late pennsylvanian and permian caused by the wide shifting of the zone of inter tropical convergence itc over the equator based on a new reconstruction of the pangean assembly in this paper climatic changes in the permian are interpreted and causes of the arid humid arid shifts are examined phases of higher humidity are often related to events of global impact like the waxing and waning of the gondwanan glaciation obtained in the south african karoo basin dwyka group but also regional events had strong climatic influence the zechstein transgression in the northern and southern permian basin as well as the bellerophon transgression of the southern alps caused the wet phase in the wuchiapingian

variscan molasse in the saar nahe basin w germany upper carboniferous and lower permian the saar nahe basin is a permocarboniferous molasse basin within the variscan orogenic chains surface access is possible in an area of 100 40 km just south of the rheinisches schiefergebirge below a thick mesozoic cover the basin has a total extension of about 300 100 km 4 1 km upper carboniferous and 1 6 km lower rotliegend grey fluviolacustrine deposits and additional 1 8 km upper rotliegend red alluvial deposits were accumulated

post failure simulations of a large slope failure using 3dec the hsien du shan slope abstract the goal of this paper is to evaluate the post failure behavior of the hsien du shan rock avalanche which was triggered by typhoon morakot in 2009 using a three dimensional 3d discrete element program namely 3dec the 3d slope topography and local joint sets are explicitly considered in the calculations and the joint sets cut the sliding rock mass into blocks with arbitrary shapes the modeled blocks exhibit the elastic behavior of the local rocks the analysis successfully simulates the wedge failure at the initiation of the landslide additionally the 3dec results clarify the local rock sliding phenomena at the boundaries of the source area the simulated depositional area correlates well with the actual area affected by the hsien du shan rock avalanche in addition the erosion of a ridge by the sliding rock near the southwestern margin of the area at an elevation of 590 m has a significant influence on the shape and size of the impacted area the interlocking effect between blocks is also considered

a numerical analysis of grain size and colour variations of a fan lake transition upper carboniferous bechtsrieth formation southern germany abstract the upper carboniferous bechtsrieth formation of the weiden basin southern germany shows a depositional evolution from an alluvial fan to a lake the sedimentary record of the probably westphalian gc member reflects gravity slides and waterlaid deposition of braided streams the younger gsc member is dominated by floodplain and sheetflood deposition locally hosting abundant freshwater limestone and clastic sediments deposited by meandering streams they grade into the nearshore and offshore lacustrine sediments of the vc member laid down during the late stephanian these subfacies types have been numerically coded as fan ratios which normalized to a 10 m drill interval resulted from the sand mud ratio multiplied by the degree of contrast and maximum clast size supplemented by rock colour which indicates oxidizing and reducing conditions of these strata and carbonate content a discrimination of these continental environments is possible and also makes the procedure amenable to cutting examinations because these terrigenous rocks have attracted the attention of exploration geologists for their coal hydrocarbon uranium and precious metal contents the source and host environments have tentatively been described in terms of these facies codes low fan ratios between 0 and 0 75 are indicative of predominantly offshore and nearshore lacustrine environments and seem most prospective for hydrocarbons uranium and gold this approach is a rapid method to improve environmental analysis and facilitate well log correlations

contraints on the evolution of the mid german crystalline rise a study of outcrops west of the river rhine several small outcrops along the western rhinegraben escarpment expose rocks which represent the western prolongation of the so called mid german crystalline rise this basement ridge separates the rhenohercynian and saxothuringian zones of the variscan belt of europe and thus marks the boundary between the external and the internal zones the variable rock association includes an orthogneissamphibolite complex weakly deformed low grade sediments devonian and visean and a number of different syn to post orogenic granodioritic to granitic intrusives all crosscut by late lower carboniferous undeformed lamprophyric dikes and unconformable overlain by permian sediments and volcanics

paleopositions of the saxothuringian northern vosges pfalz odenwald spessart in variscan times paleomagnetic investigation abstract in the saxothuringian zone thermal demagnetization of 581 specimens of late devonian early carboniferous gabbros diorites granodiorites gneisses and schists yields different time dependent paleomagnetic directions the oldest c n directions vgp northern vosges 19 n 222 e spessart 27 5 n 227 e were emplaced during crystallization of the visean plutonics in the time range 340 330 ma c p directions n v 47 n 241 e mostly characterized by low unblocking temperatures are interpreted as slightly younger overprints or as resultant vectors of c n and present day directions the b directions northern vosges 14 n 132 e odenwald 6 n 128 e exist as primary magnetizations in middle late carboniferous rhyolites and as overprint in the late devonian early carboniferous plutonics the a directions sp 28 n 175 e od 26 n 168 e correspond to overprints emplaced later in the late carboniferous the a directions northern vosges 49 n 155 e pfalz 45 n 154 e odenwald 48 n 151 e spessart 47 n 165 e are consistent with the permian early triassic european directions and are present as primary directions in permian volcanics the late carboniferous permo triassic overprints are mainly characterized by high unblocking temperatures due to the presence of secondary hematite the deviations from c to b and from b to a are interpreted as due to two successive block rotations the first 90 clockwise or counterclockwise the second 40 clockwise and the deviation from a to a to a 2500 km northward drift of the saxothuringian