contact diagenesis the effect of an intrusion on reservoir quality in the triassic sherwood sandstone group northern ireland abstract intrusion of a dolerite sill into clay bearing arkosic triassic sherwood group sandstones with moderate porosity 22 and high but anisotropic permeability mode 500 md led to the progressive transformation of precursor diagenetic minerals in the host rock locally pore filling mg rich smectite saponite quartz and dolomite existing in the rock following earlier burial diagenesis reacted to produce grain coating flakes of talc at the lowest contact temperatures 130 180 c based on equilibrium reaction path and thermal history calculations at higher temperatures 200 230 c talc reacted with calcite to produce an actinolitic amphibole close to the intrusion at temperatures of 250 c bundles of acicular needles of actinolite protruding into open pores were produced by a second reaction involving saponite hematite and calcite framework feldspar minerals mainly k feldspars played little or no part in the reactions because there were no k al rich minerals produced by contact diagenesis and because the detrital feldspar grains are essentially unaltered thus while equilibrium may have been approached on the intrapore scale 10 m it was not achieved between grains e g detrital feldspars pore water and clays in the pores total porosity has been unaffected by the intrusion and consequent mineral reactions because reactions involved recrystallization of original pore filling minerals despite the contact diagenetic changes in the rock the permeability of the sandstone remained largely unaffected by intrusion

landslide development in a coastal valley in northern spain conditioning factors and temporal occurrence abstract sixty five landslides have been mapped in the meredal valley carved in one of the asturian precoastal ranges on mesozoic bedrock from a genetic point of view two groups of landslides can be distinguished landslides developed mainly over triassic lutites complex movements flows and rockslides and landslides developed from calcareous cliffs rock avalanches many of them are relict landslides although evidence of activity can be recognized as a result of a partial reactivation of some of the landslides four chronological classes have been established according to geomorphological criteria and the degree of preservation of the landslides a lateral plugging deposit provides a minimum age of 5050 40 b p for the oldest class in the same way a stalactite gives to the third class of landslides a minimum age of 3392 128 b p the origin of landslides can be related to the plastic behavior of lutite and the permeability of the overlying limestone which allows vertical seepage of water from a regional point of view landslides could be connected with quaternary fluvial incision processes as well as to holocene high rainfall events

linking hydrological infinite slope stability and land use change models through gis for assessing the impact of deforestation on slope stability in high andean watersheds in the ecuadorian andes episodic slope movements comprising shallow rotational and translational slides and rapid flows of debris and soil material are common consequently not only considerable financial costs are experienced but also major ecological and environmental problems arise in a larger geographical area sediment production by slope movement on hillslopes directly affects sediment transport and deposition in downstream rivers and dams and morphological changes in the stream channels in developing countries world wide slope movement hazards are growing increasing population pressure and economic development force more people to move to potentially hazardous areas which are less suitable for agriculture and rangelands this paper describes the methods used to determine the controlling factors of slope failure and to build upon the results of the statistical analysis a process based slope stability model which includes a dynamic soil wetness index using a simple subsurface flow model the model provides a time varying estimate of slope movement susceptibility by linking land use data with spatially varying hydrologic soil conductivity evapotranspiration soil wetness and soil strength properties the slope stability model was applied to a high andean watershed gordeleg catchment 250 ha southern ecuadorian andes and was validated by calculating the association coefficients between the slope movement susceptibility map of 2000 and the spatial pattern of active slope movements as measured in the field with gps the proposed methodology allows assessment of the effects of past and future land use change on slope stability a realistic deforestation scenario was presented past land use change includes a gradual fragmentation and clear cut of the secondary forests as observed over the last four decades 1963 2000 future land use change is simulated based on a binary logistic deforestation model whereby it was assumed that future land use change would continue at the same rate and style as over the last 37 years 1963 2000 c 2002 elsevier science b v all rights reserved

geomorphology internal structure and evolution of alluvial fans at motozintla chiapas mexico abstract alluvial fans and terraces develop in diverse regions responding to different tectonic and climatic conditions the motozintla basin is located in the state of chiapas southern mexico and has an e w orientation following the trace of the left lateral polochic fault the evolution of the motozintla basin and the alluvial plain is related to several factors such as fault movement intense erosion by hydrometeorological events and anthropogenic activity this study presents the geomorphology of the alluvial plain that between the villages of motozintla and mazapa de juarez exposes 31 alluvial fans 5 hanging terraces and 13 ramps fourteen of these alluvial fans have been truncated by the polochic fault exposing maximum uplifts of 12 m the internal structure of truncated fans consists of single massive beds monolithologic fans or stacked beds polygenetic fans the fans stratigraphy is made of debris flow deposits separated by paleosols and minor hyperconcentrated flows fluviatile beds and pyroclastic fall deposits the reconstruction of the stratigraphy assisted by radiocarbon geochronology suggests that these fans have been active since late pleistocene 25 ka to the present this record suggests that at least 10 events have been recorded at the fan interior during the past 1840 years one of these events at 355 65 14 c yrs bp cal yrs ad 1438 to 1652 can be correlated across the fans and is likely associated with an extreme hydrometeorologic event the presence of a 165 60 14 c yrs bp cal yrs ad 1652 1949 debris flow deposit within the fans suggests that movement along the polochic fault formed the fans scarp afterwards in fact a historic earthquake along the fault occurred east of motozintla on july 22 1816 with a m w of 7 5 7 75 recent catastrophic floods have affected motozintla in 1998 and 2005 induced by extreme hydrometeorological events and anthropogenic factors therefore scenarios for motozintla involved several types of mass movement processes that pose a serious hazard and threat to the inhabitants of the region

the impact of wallachian settlement on relief and alluvia composition in small valleys of the carpathian mts czech republic abstract the impact of the wallachian settlement on small mountain catchments has been studied at the example of skor ansk and hartisov streams moravskoslezske beskydy mts western outer carpathians between the 16th and the 19th centuries the wallachian people introduced pastoral management originating from the woodless balkans to the forested mid altitude mountain area under study this area was subjected to rapid settlement intense grazing in forests and slash and burn deforestation to assess the geomorphic effects of wallachian activity in the catchments studied grain size structure organic matter content and the plant macrofossil composition of the alluvia forming terrace levels in the mouths of the skor ansk and hartisov streams were analysed radiocarbon dating 137 cs and 210 pb analyses and dendrochronological dating were also applied to determine the age of the alluvia studied the results were compared with land use and land cover changes recorded on archival maps and pictures and with population changes in the study area it was found that the two successive trends of catchment settlement and later depopulation have led to the development of inset terraces on the outlet fans of the skor ansk and hartisov streams in the study catchments both settlement deforestation and depopulation land abandonment occurred very rapidly which also caused abrupt geomorphic changes before human disturbance fluvial erosion and the redeposition of older pleistocene deposits predominated as a result coarse gravel alluvia were deposited within stream channels the stage of massive overbank accumulation of fine grained alluvia was a reflection of intensified delivery of slope material into valley floors from catchments deforested by the wallachians the later stage of vertical incision of channels resulted from the decrease of sediment supply from hillslopes to river channels during catchment depopulation and afforestation

geological hazards in loess terrain with particular reference to the loess regions of china abstract the considerable morphodynamic energy provided by the continuing tectonic evolution of asia is expressed in high erosional potentials and very high rates of sediment production that make this continent unequalled as a terrestrial source of primary silt many of these environments are hazardous threatening human occupation health and livelihood especially in regions of dense population such as the loess lands of north china dry loess can sustain nearly vertical slopes being perennially under saturated however when locally saturated it disaggregates instantaneously such hydrocompaction is a key process in many slope failures made worse by an underlying mountainous terrain of low porosity rocks gully erosion of loess may yield very high sediment concentrations 60 by weight characteristic vertical jointing in loess influences the hydrology enlarged joints develop into natural sub surface piping systems which on collapse produce a loess karst terrain collapsible loess up to 20 m thick is common on the western loess plateau foundation collapse and cracked walls are common many rapid events following periods of unusually heavy monsoonal rain slope failure is a major engineering problem in thick loess terrain flow slide and spread types being common the results are often devastating in both urban and rural areas an associated hazard is the damming of streams by landslides the human population increases the landslide risk in china notably through imprudent land use practices including careless water management a number of environmentally related endemic diseases arise from the geochemistry of loess and its groundwaters including fluorosis cretinism kaschin beck disease keshan disease and goitre the chinese desert margins also have a major atmospheric dust problem the effect of such dust upon human health in these extensive regions including many large cities has yet to be evaluated but pneumoconiosis is thought to affect several million people in north and west china

variations in thickness of layer 3 dominate oceanic crustal structure abstract seismic refraction studies have determined that while much of the crust underlying the world s oceans is about 7 km thick it also occurs in lesser and considerably greater thicknesses here we show that vastly different thicknesses of oceanic crust formed at ridges by seafloor spreading are generally characterized by the two gradient velocity structure recognized as typical of 6 7 km thick oceanic crust adopting a standard we study ninety published seismic velocity structures of oceanic crust ranging in thickness from 2 to 37 km several structures formed in midplate settings ocean islands and seamounts are also considered for comparison regardless of origin ridge or midplate we find that the percentage of the whole crust formed by layer 2 systematically decreases with increasing total crustal thickness while the average velocity of layer 2 varies widely for all crust the average velocity of layer 3 increases systematically with increases in the average whole crustal thickness and velocity crust formed in midplate settings differs in that the thickness of layer 2 velocity crust is generally two to three times that of crust formed at ridges residual depths were calculated for oceanic crust by removing the effects of sediment loading and subsidence due to lithospheric cooling most of the data fall close to a model whereby different crustal thicknesses result from different extents of partial melting of oceanic upper mantle the crustal sections were restored to zero age assuming the average depth of emplacement for 7 km thick oceanic crust is 2 5 km below sea level from this restoration it appears that the depth to the top of layer 3 at the time it was formed is 4 25 1 25 km below sea level regardless of whole crustal thickness or spreading rate these results suggest that the mechanism of construction of oceanic crust is in many ways remarkably uniform despite very large changes in the total thickness of the crust produced very basic questions remain it is for instance not at all clear why layer 2 and layer 3 exist in the proportions they do while neutral buoyancy or melt trapping at the base of a brittle lid may account for local properties of the layer 2 3 boundary they do not seem adequate to account for the global phenomenon

extension discrepancy at north atlantic nonvolcanic rifted margins depth dependent stretching or unrecognized faulting rifted margins show an apparent discrepancy between the amount of extension measurable from faults and the amount of crustal or lithospheric thinning determined from wide angle data or subsidence this extension discrepancy has been interpreted in terms of depth dependent stretching in which the upper crust is extended and thinned far less than the rest of the lithosphere here i show that at those nonvolcanic margins where the velocity structure is well known the upper and lower crust appear to thin equally toward the margin implying that the discrepancy is not due to depth dependent stretching but more likely due to unrecognized polyphase and top basement faulting

natural and human induced landsliding in the garhwal himalaya of northern india after the march 28 1999 garhwal earthquake 338 active landslides including 56 earthquake induced landslides were mapped in a 226 km 2 study area in the garhwal himalaya northern india these landslides mainly comprised shallow failures in regolith and highly weathered bedrock involving avalanches slides and flows the total volume of active 33 landslide debris in the region was estimated to be 1 3 million m including 0 02 million m 2 of the total volume moved during and within a few days of the earthquake the denudation produced by the active landsliding within the study area is equivalent to a maximum landscape lowering of 5 7 mm if active landsliding persists for a duration of between 1 and 10 years then denudation due to landsliding is in the order of 0 6 6 mm a y1 approximately two thirds of the landslides in this region were initiated or accelerated by human activity mostly by the removal of slope toes at road cuts suggesting that human activity is accelerating denudation in this region three ancient catastrophic landslides each involving 1 million m 3 of debris were identified and two were dated to the early middle holocene using cosmogenic radionuclide 10 be and 26 al cosmogenic radionuclide 10 be and 26 al were also used to date strath terraces along the alaknanda river in lower garhwal himalaya to provide an estimate of 4m m a y1 for the rate of regional denudation throughout the holocene natural landsliding therefore contributes 5 50 of the overall denudation in this region and is important as a formative process in shaping the landscape q 2001 elsevier science b v all rights reserved

dating of post glacial landforms in the central howgills little is known of holocene landform development in upland britain this paper describes a site at middle langdale in the howgill fells of cumbria where large but now stabilized and inactive gullies cut through periglacial material at the base of the gullies large debris cones have buried earlier alluvial sediments on the valley floor on these sediments and buried by the debris cones is a well developed organic soil from which two 14c dates have been obtained in an attempt to estimate the age range of the soil these dates range from 2580 55 years bp for the fine particulate fraction from the base of the organic horizon to 940 95 years bp for fossil rootlets from the uppermost organic layer immediately below the overlying debris cones the pollen evidence suggests that the valley floor site was initially dominated by alder carr and later by a juncus marsh with birch alder and hazel nearby the pollen from the surrounding upland area suggests woodland on the valley sides dominated by oak and elm that was later replaced by a more open environment rich in heath species and in which disturbed ground species were present the magnetic evidence indicates a stable local environment during soil formation but shows a sudden inwash of unweathered debris at the top of the buried soil the evidence suggests that the valley floor was geomorphologically stable throughout the period of soil formation although there was a local change in valley floor vegetation and a reduction of woodland cover on the valley sides at sometime during the period the evidence then points to major geomorphological changes a wave of soil erosion gully development and debris cone deposition perhaps following the scandinavian introduction of sheep farming in the tenth century a d

formation of zeolites in open hydrologic systems in contrast to those deposits formed by the alteration of volcanic ash in saline alkaline lakes discussed in the chapter by hay and sheppard this volume large volumes of tuffaceous sediments around the world have been transformed to zeolites and other authigenic silicate minerals by the action of percolating water in open hydrologic systems these include systems that have experienced significant chemical and hydrologic exchanges with the surrounding environment tephra sequences exposed to open system alteration commonly show a vertical zonation of zeolites and other authigenic minerals that reflects the chemical changes in meteoric water moving through the system flow in an open hydrologic system can either be downward or have a downward component where meteoric water enters the system resulting in a vertical or nearly vertical zonation of water composition and authigenic minerals the original pyroclastic materials of tuffaceous sediments may have been laid down in the sea close to the volcanic sources air laid onto the land surface or reworked into fluviatile and freshwater lacustrine environments open system zeolite deposits are most common in nonmarine rocks although many are known in sediments that were deposited in shallow marine environments zeolite deposits of the open system type are commonly several hundred meters thick and can be traced laterally for several tens of kilometers many examples of zeolite deposits that formed from land laid tephra have been recognized in the western united states but most of the large marine deposits are in japan and in southern and southeastern europe because of their relatively large and commonly discontinuous areal extent open system deposits have not been studied in as much detail as some other types of zeolite deposits in sedimentary rocks however studies of several key areas have provided a sound basis for the current understanding of this type of zeolite body zeolitic alteration can take place

the contribution of landslides to landscape evolution in europe abstract after a review of some analytical and conceptual models of slope evolution with the intervention of mass movements a proposal is made of a series of indicators for the quantitative description of landscape evolution in relation to mass movements the ratio between landslide mobilisation rate and downwearing rate is proposed as a quantitative measure of the significance of mass movements in landscape evolution a subdivision of european regions with respect to their susceptibility to landsliding as a process of landscape evolution is proposed the role of landsliding for the evolution of landscape in some regions is described the data presented show that landsliding may in some cases be the main contributor to landscape change

classic and new dating methods for assessing the temporal occurrence of mass movements abstract establishing landslide chronologies is essential both for understanding causes of mass movements as part of fundamental geomorphological research and for the assessment of landslide hazards as part of applied geomorphology we discuss the applicability of different methods for determining landslide chronologies frequencies and dynamics in relation to the type of material being dated sampling location and type of mass movement the emphasis is on the possibilities and limitations of the different dating methods established methods such as radiocarbon dating lichenometry and dendrochronology are briefly discussed the paper focuses however on 1 new analytical techniques like accelerator mass spectrometry ams thermally ionising mass spectrometry tims and laser fusion which have led to significant improvements of established dating methods and on 2 new dating methods like optically stimulated luminescence osl dating and alpha recoil track art dating

analysis of geomorphic systems response to natural and human drivers in northern spain implications for global geomorphic change abstract an analysis of changes experienced during the last century by certain indicators of the intensity of geomorphic processes in northern spain is presented in order to test a previously formulated hypothesis the hypothesis already tested in the rio de la plata basin is that there is a global geomorphic change which implies an acceleration of geomorphic processes in general and that such acceleration is mainly due to the transformation of land surface by human activities not to climate factors sedimentation rates obtained in eight estuaries in northern spain through pb 210 and cs 137 dating of sediment cores show a general increase since the beginning of last century and particularly after the 1950s similar increases in landslide frequency have been formerly observed in some areas of the same region trends of change in sedimentation rates have been compared with those of potential natural rainfall and human indicators of the intensity of human activities that can contribute to land surface transformation drivers there seems to be no relationship between rainfall and sedimentation rate trends but the magnitude and trends of several indicators of human activity are similar to those of the latter data on landslide frequency obtained in a small study area also show a possible relationship with land use change and infrastructure development but not with rainfall the results described are coherent with the hypothesis and suggest that the process described could have a global character if this is so the worldwide observed increase in flood and landslide disasters might be a characteristic of the anthropocene and due to human induced geomorphic change rather than climate change also human induced as often assumed

flemish cap goban spur conjugate margins new evidence of asymmetry we present the combined results of deep multichannel reflection and refraction seismic surveys across the flemish cap goban spur conjugate margin pair north atlantic which we use to infer rifting style and breakup profiles on both margins cross magnetic anomaly 34 and extend into oceanic crust making it possible to observe the complete history from continental rifting through to the formation of initial oceanic crust the deep multichannel seismic mcs reflection data have previously been used to support a model of symmetric pure shear extension followed by asymmetric breakup and a sharp continent ocean boundary using both types of seismic data our results indicate instead that asymmetric structures are formed during all stages of rifting breakup and complex transition to oceanic spreading the differing nature of the two ocean continent transition zones is particularly striking for flemish cap our reprocessed image of the mcs profile clearly shows tilted fault blocks beneath back tilted sediment packages consistent with a wide region of highly thinned continental crust inferred from wide angle seismic data in contrast normal incidence and wide angle seismic data for the goban spur transition zone indicate the presence of exhumed serpentinized mantle

hydrothermal alteration and zeolitization of the fohberg phonolite kaiserstuhl volcanic complex germany the subvolcanic fohberg phonolite kaiserstuhl volcanic complex germany is an economic zeolite deposit formed by hydrothermal alteration of primary magmatic minerals it is mined due to the high 40 wt zeolite content which accounts for the remarkable zeolitic physicochemical properties of the ground rock new mineralogical and geochemical studies are carried out a to evaluate the manifestation of hydrothermal alteration and b to constrain the physical and chemical properties of the fluids which promoted hydrothermal replacement the alkaline intrusion is characterized by the primary mineralogy feldspathoid minerals k feldspar aegirine augite wollastonite and andradite the rare earth elements phase gotzenite is formed during the late stage magmatic crystallization fluid induced re equilibration of feldspathoid minerals and wollastonite caused breakdown to a set of secondary phases feldspathoid minerals are totally replaced by various zeolite species calcite and barite wollastonite breakdown results in the formation of various zeolites calcite pectolite sepiolite and quartz zeolites are formed during subsolidus hydrothermal alteration 150 c under alkaline conditions a sequence of ca na dominated zeolite species gonnardite thomsonite mesolite is followed by natrolite the sequence reflects an increase in log a text na a text h and decrease in log a text ca 2 a text h 2 of the precipitating fluid low radiogenic 87sr 86sr values indicate a local origin of the elements necessary for secondary mineral formation from primary igneous phases in addition fractures cut the intrusive body which contain zeolites followed by calcite and a variety of other silicates carbonates and sulfates as younger generations stable isotope analysis of late fracture calcite indicates very late circulation of meteoric fluids and mobilization of organic matter from surrounding sedimentary units

a methodological approach for the analysis of the temporal occurrence and triggering factors of landslides the temporal occurrence of landslides in an area of the cantabrian range during the last 120 000 years is analyzed an initial relative chronology was established on the basis of aging degree and spatial relationships between landslides and glacial and fluvial features ten landslide classes were thus identified and their chronological limits defined on the basis of 19 14c age determinations on fluvial and glacial deposits including eight new ones the chronology was tested with 14c dates obtained on landslide deposits 10 from previous work and nine new ones the chronological classes identified were compared with existing climate models for the region the type and spatial distribution of landslides in each class were also analyzed the approach made it possible to identify periods during which landslides were triggered mainly by channel incision seismic activity and rainfall increase human activity played a significant role after 5000 bp and especially in the last few centuries mobilization of materials by slope movements has increased in the region by a factor of 10 compared to pre neolithic rates

the temporal and spatial development of landslides in the axmouth lyme regis undercliffs national nature reserve devon a chronology of landsliding is presented including suggestions as to a date for initiation periods of activity known from historical sources are correlated with known periods of climatic deterioration the current morphology of the landslide slopes is closely related to the geological succession and structure these permit the landslides and their development to be differentiated on the basis of whole slope and toe morphology and much of the whole slope activity can be related to conditions at the toe examples of geomorphological maps slope categories maps and cross sections are presented along with an example of the evolutionary maps which may be derived from ordnance survey plans and aerial photographs these generally indicate that weakening of materials by weathering seepage erosion at the toe and marine erosion result in frequent mass movement events of a low magnitude these events ultimately influence the stability of larger slipped blocks behind which fail less frequently it is suggested that whole slope failures in this region have a maximum frequency of once in 120 to 150 years and that problems of interpretation of historical accounts may mean that it is very much less frequent than this

the temporal stability and activity of landslides in europe with respect to climatic change teslec main objectives and results abstract the major aim of the european project the temporal stability and activity of landslides in europe with respect to climatic change teslec was to investigate the interrelationship between landslides climate and time the research was focused on three main objectives 1 developing criteria for the recognition of landslides 2 reconstructing past distributions of landslide incidents and their relationship to climatic change parameters and 3 developing a hydrological and slope stability modelling framework using different test sites the results of the project are related to these major objectives and include 1 a technical manual for landslide recognition 2 records of landslide activity and 3 an evaluation of different hydrological and slope stability models landslide activity since 1950 has been generally high at all test sites in some areas there has almost been a continuous activity observed since the beginning of the monitoring the records before 1950 are incomplete and probably indicate a lack of data rather than a lack of landslide activity whether the observed active landslides are carrying a climate signal cannot be stated for all test sites with high confidence since some relationships between climate and landslides are uncertain thus for the present the complexity of the relationships between climate and landsliding seems to make it not feasible to establish universal laws all over europe on the other hand it was possible to establish for some areas a cumulative rainfall duration threshold for the reactivation of landslides future scenarios of regional precipitation were derived from downscaled general circulation model gcm experiments and used within simple slope hydrological and slope stability models the evaluation of hydrological and slope stability models shows that physically based models are not always the best solution due to the model complexity and data requirements for shallow landslides more simple tank models are sometimes the better alternative future model development should strengthen considerations of fissure flow sudden changes in permeability larger landslide volumes and complex landslide topography

miocene fossil hydrothermal system associated with a volcanic complex in the andes of central chile abstract cenozoic deposits in the andes of central chile have been affected by very low grade burial metamorphism at about 33 s in the cuesta de chacabuco area approximately 53 km north of santiago two oligocene and miocene volcanic units form a ca 1300 m thick rock pile the miocene unit corresponds to a volcanic complex composed of two eroded stratovolcanoes secondary mineral assemblages in both units were studied petrographically and using x ray diffraction and electron microprobe analyses most of the igneous minerals are wholly or partially preserved and the ubiquitous secondary minerals are zeolites and mafic phyllosilicates the alteration pattern observed is characterized by a lateral zonation in secondary mineralogy related to a lateral increase in temperature but not to stratigraphic depth the following three zones were established mainly based on the distribution of zeolites zone i comprises heulandite thomsonite mesolite stilbite and tri smectite zone ii contains laumontite yugawaralite prehnite epidote and chlorite and zone iii comprises wairakite epidote chlorite diopside biotite and titanite for each zone the following temperature ranges were estimated zone i 100 180 c zone ii 180 270 c and zone iii 245 310 c the alteration episode was characterized by a high p fluid p total ratio ca 1 0 although slightly variable a high geothermal gradient of ca 160 c km 1 and fluid pressures below 500 bars although temperature was the main control on the mineral zonation several interrelated parameters mainly fluid composition porosity and permeability were also important hot near neutral to slightly alkaline ph alkali chloride hydrothermal fluids with very low dissolved co 2 contents deposited the secondary minerals the alteration pattern is the result of depositing fluids in outflow regions from a hydrothermal system developed inside a volcanic complex during the miocene the hydrothermal system has been eroded to a maximum depth of 1 7 km

mineral processing characteristics of natural zeolites from the aritayn formation of northeast jordan the inferior grade of natural zeolite ores in comparison to their synthetic counterparts has been identified as a possible factor responsible for the relatively small market share of the former this paper describes the results of laboratory scale mineral processing trials carried out on relatively low grade natural zeolite ores from the aritayn formation of northeast jordan to improve their purity through removal of unwanted gangue constituents appropriate sample preparation and mineral processing methods were selected which utilised contrasts in texture particle size hardness specific gravity and magnetic susceptibility between gangue and target constituents to achieve beneficiation sample preparation by autogenous comminution was able to selectively liberate zeolite minerals from the surface of pyroclasts and therefore was an effective method of pre concentration subsequently using widely available magnetic and gravity separation equipment a high grade concentrate containing 89 zeolite was produced at a recovery of 37 from a lapilli tuff of 47 head grade

continental hyperextension mantle exhumation and thin oceanic crust at the continent ocean transition west iberia new insights from wide angle seismic hyperextension of continental crust at the deep galicia rifted margin in the north atlantic has been accommodated by the rotation of continental fault blocks which are underlain by the s reflector an interpreted detachment fault along which exhumed and serpentinized mantle peridotite is observed west of these features the enigmatic peridotite ridge has been inferred to delimit the western extent of the continent ocean transition an outstanding question at this margin is where oceanic crust begins with little existing data to constrain this boundary and a lack of clear seafloor spreading magnetic anomalies here we present results from a 160 km long wide angle seismic profile western extension 1 travel time tomography models of the crustal compressional velocity structure reveal highly thinned and rotated crustal blocks separated from the underlying mantle by the s reflector the s reflector correlates with the 6 0 7 0 km s 1 velocity contours corresponding to peridotite serpentinization of 60 30 respectively west of the peridotite ridge shallow and sparse moho reflections indicate the earliest formation of an anomalously thin oceanic crustal layer which increases in thickness from 0 5 km at 20 km west of the peridotite ridge to 1 5 km 35 km further west p wave velocities increase smoothly and rapidly below top basement to a depth of 2 8 3 5 km with an average velocity gradient of 1 0 s 1 below this velocities slowly increase toward typical mantle velocities such a downward increase into mantle velocities is interpreted as decreasing serpentinization of mantle rock with depth

use of zeolitic tuff in the building industry zeolite rich volcanic tuffs are widely distributed in almost every country of the world where they are present in low medium or high grade million ton deposits even though the formation of the zeolite minerals may have followed different genetic paths the zeolitic rocks have in common a matrix of finely crystalline zeolite that cements the other nonzeolitic particles and is responsible for the overall mechanical properties of the material zeolitic tuffs have been employed since pre historic times in construction mostly as dimension stone this use is still the most common of natural zeolites in the building industry although other applications have recently come to the forefront such as lightweight aggregate or as additives for manufacturing blended cements given the fact that much of this material is excavated and used locally and that the market demand is strongly affected by the trends of the building industry estimates of the worldwide zeolitic tuff production for construction purposes are difficult to make in italy where the use of zeolitic tuff as dimension stone is commonplace about 75 quarries were reported in operation in 1992 with total production of about 3 x 106 tons per year aiello 1995 more recently this production has decreased due to the crisis of the building industry and in 1998 it amounted to about 1 5 106 tons per year in japan the production of tuff as dimension stone is currently about 4 105 tons per year n kuchitsu national research institute of cultural properties tokyo japan pers comm 1996 considering that zeolitic tuff is used as dimension stone in many other countries as well e g bulgaria cuba germany greece hungary mexico romania and turkey the current worldwide zeolitic tuff consumption as dimension stone is about 3 106 tons per year information is even more

stability analysis of a human influenced landslide in eastern belgium article i nfo the area of the pays de herve in eastern belgium is strongly affected by recent landslide activity dormant landslides are widespread in the region and some of these dormant landslides have been reactivated by human activity such as highway construction suburban development or building of industrial sewage pipes the investigated landslide was reactivated by heavy rainfall events in the late 1990s during this reactivation an existing industrial sewage pipe was damaged and the chemically loaded waste water drained into the landslide mass the current landslide movement is assumed to be heavily influenced by the additional water supply as well as by the chemical activity of univalent ions in the clay fraction leading to a decreased shear resistance consequently the movement triggering rainfall thresholds are reduced and result in a decreased overall slope stability this study describes a general methodology of field investigation data collection and laboratory testing for an exploratory study influences of chemical properties of soil and soil water and their effects on landslide stability are analysed discussed and related to findings of other studies although no clear empirical evidence for a dependency between slope stability and ionic loaded soil water was found in this study we suggest the existence for such a relationship we conclude that this particular landslide would not have moved based on current environmental conditions the leaking waste water might favour current landslide movement

deciphering the effect of climate change on landslide activity a review abstract increased landslide activity is commonly listed as an expected impact of human induced climate change this paper examines the theoretical and empirical bases for this assertion it identifies the mechanisms by which climate can induce landsliding and examines the manner in which these mechanisms may respond to changes in a range of climatic parameters it is argued that inherent limiting stability factors which vary with different terrain conditions and landslide types ultimately govern the nature of response to changing climate several modelling approaches are evaluated on the basis of their potential to predict landslide response to climate projections given reliable input data of appropriate form and resolution the existing slope stability hydrological and statistical models are for the most part capable of yielding useful prognoses on occurrence reactivation magnitude and frequency of landsliding while there is a strong theoretical basis for increased landslide activity as a result of predicted climate change there remains a high level of uncertainty resulting from the margins of error inherent in scenario driven global climate predictions and the lack of sufficient spatial resolution of currently available downscaled projections examples from new zealand are used to illustrate the extent to which changes resulting from human activity have affected slope stability changes resulting from human activity are seen as a factor of equal if not greater importance than climate change in affecting the temporal and spatial occurrence of landslides

soil erosion and sedimentation indicated by caesium 137 jackmoor brook catchment devon england summary the tracer caesium 137 was used to study the status of soil erosion and sedimentation in the jackmoor brook catchment devon u k it was postulated that 1 sites at the top of a cultivated slope should be most depleted of caesium 137 2 sites at the base of a slope should contain greater amounts of caesium 137 and have a distinctive depth profile 3 hillslope erosion indicated by caesium 137 levels should be related to slope length and angle and 4 caesium 137 levels should discriminate between the chief source of sediment transferred to the stream cultivated soils and uncultivated soils under pasture orchards and woodland these hypotheses were tested in two contrasting physiographic areas of the basin depletion of caesium 137 levels at the top of slopes indicated soil erosion and deeper than plough depth caesium 137 profiles at the base of slopes indicated sedimentation these characteristics were most marked in the steeper upper jackmoor portion of the catchment slope length effects on soil movement were more difficult to ascertain from the caesium 137 levels but soil sampling of contrasting land uses showed that cultivated soils had significantly less caesium 137 probably as a result of soil erosion in general the hypotheses were supported and the utility of the caesium 137 technique was confirmed

human impact on geomorphic processes and hazards in mountain areas in northern spain abstract the temporal occurrence of slope movements their contribution to relief evolution and human influence on those processes in two study areas of northern spain are presented the work is based on temporal analyses covering 100 ka in one study area and 43 years in the other temporal analysis has been the basis for quantitatively assessing the magnitude of human influence and developing landslide susceptibility and hazard models with known independently tested prediction capability the results obtained in one study area show a relationship between landsliding periods and increasing precipitation during upper pleistocene and holocene significant increases of landslide frequency and mobilisation rate were also found around 5500 and 200 years ago those moments coincide with two periods of intensified human presence and activities neolithic and industrial revolutions the increase observed represents about one order of magnitude from pre neolithic to present a similar increase has been found between 1954 and 1997 in the other study area the latter increase shows no relationship with changes in climate parameters or seismic activity a fairly good correlation has been found between landslide frequency and socioeconomic indicators of human activity sedimentation rates in two neighbouring estuaries were determined and significant increases particularly in the second part of last century were also found evidence obtained suggest that the increases observed in the frequency of slope instability events and therefore hazard denudation and sedimentation rates are due to a greater extent to indirect geomorphologic changes caused by human action rather than climate change detailed analysis of landslide frequency during that 43 year period has also been used to produce and validate landslide susceptibility models and obtain landslide hazard maps with known prediction accuracy validation tests were carried out comparing susceptibility maps based on landslides that have occurred in the past with the ones occurring in several later periods prediction capability of models could thus be determined validation of susceptibility maps using data derived from the temporal analysis of landslides was used to obtain hazard maps expressed as probability of new ruptures in a given time period on the basis of past trends in terrain behaviour possible impacts of a growing influence of human activities on the terrain have been incorporated into the assessment of future hazards by considering different scenarios

the authigenic zeolites of the aritayn volcaniclastic formation north east jordan in the aritayn volcaniclastic formation the formation of zeolites is associated with the transformation of sideromelane into palagonite by reaction with percolating water in an open hydrological system three vertical zones are described characterised by fresh sideromelane at the top zone 1 palagonite smectite in the middle zone 2 and zeolites at the bottom zone 3 within zone 3 a phillipsite chabazite sub zone overlies a faujasite phillipsite sub zone the paragenetic sequence fresh sideromelane palagonite smectites saponite montmorillonite faujasite phillipsite chabazite natrolite calcite resembles those described in the literature except for the early formation of smectites in the jordanian occurrences faujasite is more abundant in these zeolitic tuffs than at any other locality in the world that has yet been described and the tuffs are considered to have excellent potential for beneficiation

human influence in geomorphology abstract the human influence in geomorphology has a long history and major contributions have for example been made by shaler mcgee gilbert and marsh however in the last two decades concern with global environmental change has brought the role of anthropogeomorphology into sharper focus global warming if it occurs will have important implications for many geomorphological processes and phenomena as a result of the direct effects of warming as a consequence of other related climatic changes e g precipitation change and as a result of climatically moderated changes in major geomorphologically significant variables e g vegetation cover large uncertainties exist with respect to such matters as hydrological response the frequency of tropical cyclones the speed and degree of permafrost degradation the response of glaciers and ice caps the extent of sea level rise the reaction of beaches to rising sea levels and the state of wetlands deltas and coral reefs other human activities may serve to compound the effects of global geomorphological proccesses given the uncertainties of so many of the environmental changes there is a great need to obtain a greater understanding of the rates and mechanisms of landform response geomorphologists need inter alia to establish long term study sites that will generate base line data to monitor the location and rate of change using sequential cartographic and remote sensing materials to determine information on natural background levels and long term trends by means of data gained from cores to gain a more profound understanding of the operation of geomorphological systems particularly with regard to sensitivities and thresholds and to appreciate the consequences of deliberate manipulation of environmental systems by humans

an evolving research agenda for human coastal systems within the broad discourses of environmental change sustainability science and anthropogenic earth surface systems a focused body of work involves the coupled economic and physical dynamics of developed shorelines rapid rates of change in coastal environments from wetlands and deltas to inlets and dune systems help researchers recognize observe and investigate coupling in natural non human morphodynamics and biomorphodynamics this same intrinsic quality of fast paced change also makes developed coastal zones exemplars of observable coupling between physical processes and human activities in many coastal communities beach erosion is a natural hazard with economic costs that coastal management counters through a variety of mitigation strategies including beach replenishment groynes revetments and seawalls as cycles of erosion and mitigation iterate coastline change and economically driven interventions become mutually linked emergent dynamics of two way economic physical coupling is a recent research discovery having established a strong theoretical basis research into coupled human coastal systems has passed its early proof of concept phase this paper frames three major challenges that need resolving in order to advance theoretical and empirical treatments of human coastal systems 1 codifying salient individual and social behaviors of decision making in ways that capture societal actions across a range of scales thus engaging economics social science and policy disciplines 2 quantifying anthropogenic effects on alongshore and cross shore sediment pathways and long term landscape evolution in coastal zones through time including direct measurement of cumulative changes to sediment cells resulting from coastal development and management practices e g construction of buildings and artificial dunes bulldozer removal of overwash after major storms and 3 reciprocal knowledge and data exchange between researchers in coastal morphodynamics and practitioners of coastal management future research into human coastal systems can benefit from decades of interdisciplinary work on the complex dynamics of common pool resources from computational efficiency and new techniques in numerical modeling and from the growing catalog of high resolution geospatial data for natural and developed coastlines around the world

crustal structure of the trans atlantic geotraverse tag segment mid atlantic ridge 26 10 n implications for the nature of hydrothermal circulation and detachment faulting at slow spreading ridges new seismic refraction data reveal that hydrothermal circulation at the trans atlantic geotraverse tag hydrothermal field on the mid atlantic ridge at 26 10 n is not driven by energy extracted from shallow or mid crustal magmatic intrusions our results show that the tag hydrothermal field is underlain by rocks with high seismic velocities typical of lower crustal gabbros and partially serpentinized peridotites at depth as shallow as 1 km and we find no evidence for low seismic velocities associated with mid crustal magma chambers our tomographic images support the hypothesis of tivey et al 2003 that the tag field is located on the hanging wall of a detachment fault and constrain the complex dome shaped subsurface geometry of the fault system modeling of our seismic velocity profiles indicates that the porosity of the detachment footwall increases after rotation during exhumation which may enhance footwall cooling however heat extracted from the footwall is insufficient for sustaining long term high temperature hydrothermal circulation at tag these constraints indicate that the primary heat source for the tag hydrothermal system must be a deep magma reservoir at or below the base of the crust

sequential faulting explains the asymmetry and extension discrepancy of conjugate margins rifted continental margins are the sites that record the thinning and break up of continents to form new oceans cesar ranero and marta perez gussinye use seismic imaging to accurately measure fault extension at the conjugate west iberia and newfoundland margins and compare this to crustal thinning they use these observations to create a balanced kinematic model of rifting that resolves the extension discrepancy in which crustal thinning appears to be greater than the extension caused by brittle faulting by producing both fault controlled crustal thinning which progresses from a rift basin to the asymmetric structure and extreme thinning of conjugate rifted margins these authors use seismic imaging to accurately measure fault extension at the conjugate west iberia and newfoundland margins and compare this with crustal thinning they use these observations to create a balanced kinematic model of rifting that resolves the extension discrepancy where crustal thinning seems to be greater than the extension caused by brittle faulting during early extension cold continental lithosphere thins and subsides creating rift basins if extension continues to final break up the split and greatly thinned plates subside deep below sea level to form a conjugate pair of rifted margins although basins and margins are ubiquitous structures the deformation processes leading from moderately extended basins to highly stretched margins are unclear as studies consistently report that crustal thinning is greater than extension caused by brittle faulting1 2 3 4 this extension discrepancy might arise from differential stretching of brittle and ductile crustal layers2 but that does not readily explain the typical asymmetric structure of conjugate margins5 6 in cross section one margin displays gradual thinning accompanied by large faults and the conjugate margin displays abrupt thinning but smaller scale faulting5 whole crust detachments active from early in the rifting could in theory create both thinning and asymmetry1 but are mechanically problematical furthermore the extension discrepancy occurs at both conjugate margins leading to the apparent contradiction that both seem to be upper plates to a detachment fault7 8 alternative models propose that much brittle extension is undetected because of seismic imaging limitations caused either by subseismic resolution faulting9 invisible deformation along top basement 100 km scale detachments8 or the structural complexity of cross cutting arrays of faults3 here we use depth migrated seismic images to accurately measure fault extension and compare it with crustal thinning the observations are used to create a balanced kinematic model of rifting that resolves the extension discrepancy by producing both fault controlled crustal thinning which progresses from a rift basin to the asymmetric structure and extreme thinning of conjugate rifted margins contrary to current wisdom the observations support the idea that thinning is to a first degree explained by simple andersonian faulting that is unambiguously visible in seismic data

the peridotite ridge province in the southern iberia abyssal plain seismic constraints revisited the west iberia margin has become the type example of a magma starved margin in which extension during breakup led to the exhumation of mantle rocks apparently over a broad area much of our understanding of this process is based on geophysical and drilling data from the southern iberia abyssal plain where the seaward part of the region of exhumed mantle is comprised of a series of margin parallel basement ridges here we analyse wide angle and normal incidence seismic data from a series of intersecting profiles across this peridotite ridge province and develop a three dimensional picture of its structure using these seismic data we infer a location and age magnetic anomaly m1 125 127 ma of first formed oceanic crust in this region that are consistent with ocean drilling program data and data from the conjugate margin we infer that the peridotite ridge province is about 70 km wide with strong serpentinization 75 at the top of basement reducing to much lower degrees 25 around 2 km below we map the geometry of some prominent reflectors on the landward margin of the peridotite ridge province that likely represent detachment faults and show that one of these has a domal structure similar to that of detachment faults at slow to ultra slow spreading mid ocean ridges

sediment flux from a mountain belt derived by landslide mapping in humid uplands landsliding is the dominant mass wasting process in the western southern alps of new zealand landslides are scale invariant and have a power law magnitude frequency distribution independent studies from other regions suggest that this is a general property of landsliding this observation is of critical importance to the evaluation of the impact of events of different length scales over different time intervals on landscape evolution it is particularly useful when estimating regional geomorphic rates because it constrains the frequency and overall significance of extreme events which cannot otherwise be evaluated by integrating the complete response of the system we estimate the regional denudation rate due to landsliding to be 9 4 mm yr 1 sediment discharge from the western southern alps is dominated by landslide derived material

a mechanism to thin the continental lithosphere at magma poor margins crustal thinning where continental plates break apart can be accomplished by a system of conjugate concave downward faults instead of multiple normal faults through exhumation of mid crustal and mantle material where continental plates break apart slip along multiple normal faults provides the required space for the earth s crust to thin and subside1 after initial rifting however the displacement on normal faults observed at the sea floor seems not to match the inferred extension2 here we show that crustal thinning can be accomplished in such extensional environments by a system of conjugate concave downward faults instead of multiple normal faults our model predicts that these concave faults accumulate large amounts of extension and form a very thin crust 10 km by exhumation of mid crustal and mantle material this transitional crust is capped by sub horizontal detachment surfaces over distances exceeding 100 km with little visible deformation our rift model is based on numerical experiments constrained by geological and geophysical observations from the alpine tethys and iberia newfoundland margins3 4 5 6 7 8 9 furthermore we suggest that the observed transition from broadly distributed and symmetric extension to localized and asymmetric rifting is directly controlled by the existence of a strong gabbroic lower crust the presence of such lower crustal gabbros is well constrained for the alpine tethys system4 9 initial decoupling of upper crustal deformation from lower crustal and mantle deformation by progressive weakening of the middle crust is an essential requirement to reproduce the observed rift evolution this is achieved in our models by the formation of weak ductile shear zones

emag2 a 2 arc min resolution earth magnetic anomaly grid compiled from satellite airborne and marine magnetic measurements 1 a global earth magnetic anomaly grid emag2 has been compiled from satellite ship and airborne magnetic measurements emag2 is a significant update of our previous candidate grid for the world digital magnetic anomaly map the resolution has been improved from 3 arc min to 2 arc min and the altitude has been reduced from 5 km to 4 km above the geoid additional grid and track line data have been included both over land and the oceans wherever available the original shipborne and airborne data were used instead of precompiled oceanic magnetic grids interpolation between sparse track lines in the oceans was improved by directional gridding and extrapolation based on an oceanic crustal age model the longest wavelengths 330 km were replaced with the latest champ satellite magnetic field model mf6 emag2 is available at http geomag org models emag2 and for permanent archive at http earthref org cgi bin er cgi s erda cgi n 970

quantitative landslide risk assessment and mapping on the basis of recent occurrences abstract a quantitative procedure for mapping landslide risk is developed from considerations of hazard vulnerability and valuation of exposed elements the approach based on former work by the authors is applied in the bajo deba area northern spain where a detailed study of landslide occurrence and damage in the recent past last 50 years was carried out analyses and mapping are implemented in a geographic information system gis the method is based on a susceptibility model developed previously from statistical relationships between past landslides and terrain parameters related to instability extrapolations based on past landslide behaviour were used to calculate failure frequency for the next 50 years a detailed inventory of direct damage due to landslides during the study period was carried out and the main elements at risk in the area identified and mapped past direct monetary losses per type of element were estimated and expressed as an average specific loss for events of a given magnitude corresponding to a specified scenario vulnerability was assessed by comparing losses with the actual value of the elements affected and expressed as a fraction of that value 0 1 from hazard vulnerability and monetary value risk was computed for each element considered direct risk maps pixel year were obtained and indirect losses from the disruption of economic activities due to landslides assessed the final result is a risk map and table combining all losses per pixel for a 50 year period total monetary value at risk for the bajo deba area in the next 50 years is about 2 4 106 euros

the s reflector west of galicia spain evidence from prestack depth migration for detachment faulting during continental breakup the mechanism of continental extension and breakup and the role of detachment faults in these processes are currently the subject of intense debate one possible detachment fault is the s reflector imaged as an undulating in time locally discontinuous reflection on existing seismic profiles west of iberia here we present new images in depth of the four margin normal profiles across the west galicia rifted margin where the s reflector was originally defined and is best imaged it is shown that faults bounding wedge shaped units of late synrift sediments which hence were active during rifting immediately prior to breakup appear to detach at shallow levels onto the s reflector s itself appears as a continuous locally domal feature and does not generally appear offset the waveform of s is compatible with a reflection from a single interface such as a sharp tectonic boundary the depth sections show that s was active at 1 3 km below the seafloor during final rifting s is interpreted as a brittle detachment fault which controlled the final breakup of the continent west of galicia furthermore the data provide constraints on the sense of shear of s analogy with detachment terranes the present synrift and structural dips of s and the identification of a breakaway to s imply that s accommodated top to the west shear toward the east of the profiles s becomes more complex possibly because of different phases of detachment faulting and the development of both incisement and excisement structures from the geometry of wedge shaped sedimentary units deposited during faulting above s it also appears that s was active at an angle of 20 or less and hence may be considered a genuine low angle normal fault

the response of slope and channel systems to various types of extreme rainfall a comparison between the temperate zone and humid tropics abstract the mountain slopes and river channels of the temperate zone and of the humid tropics are modelled by various types of extreme rainfall in the flysch carpathians the leading role is played by continuous rains causing floods and landslides rainy seasons wet years mobilizing deep landslides and to a smaller degree by local downpours in the darjeeling himalaya with young relief and uplift tendency the main influence on modelling the mountain slopes and river channels have been the extreme continuous rains separated by several decades of normal rainy season playing the preparatory or relaxation role with simultaneous transformation of slopes and river channels in both cases human impact has caused the acceleration of runoff and mobilization of sediment the higher extremes of precipitation and steep slopes in the humid tropics are balanced to some extent in temperate zones by the lower infiltration rates and lower thresholds of mass mobility on the gentle slopes originated in the periglacial environment

temporal occurrence and activity of landslides in the area of cortina d ampezzo dolomites italy abstract this article shows the results of research on landslides carried out in the area of cortina d ampezzo dolomites italy within the framework of the epoch project of the european community the investigated area where tourism activities and infrastructures are highly developed has been affected by several landslides since the retreat of the wurnian glaciers and is at present still affected by active slides and flows which endanger some villages after a geological and geomorphological description the distribution in space and time of landslides which occurred in the surroundings of cortina d ampezzo is presented the type activity frequency and when possible the age of mass movements have been outlined furthermore special attention is focused on the landslides active at present which are reactivations of ancient movements the results from the monitoring systems which were installed in order to survey kinematic and hydrogeologic parameters and define the movement rate are shown the research enables the reconstruction of the post wurmian geomorphological evolution of a site in the dolomites that appears to be very peculiar both on account of the wide distribution of landslides and the intense human activity

10be erosion rates controlled by transient response to normal faulting through incision and landsliding abstract quantifying erosion rates and how they compare to rock uplift rates is fundamental for understanding landscape response to tectonics and associated sediment fluxes from upland areas the erosional response to uplift is well represented by river incision and the associated landslide activity however characterising the relationship between these processes remains a major challenge in tectonically active areas in some cases because landslides can preclude obtaining reliable erosion rates from cosmogenic radionuclide crn concentrations here we quantify the control of tectonics and its coupled geomorphic response on the erosion rates of catchments in southern italy that are experiencing a transient response to normal faulting we analyse in situ 10be concentrations for detrital sediment samples collected along the strike of faults with excellent tectonic constraints and landslide inventories we demonstrate that 10be derived erosion rates are controlled by fault throw rates and the extent of transient incision and associated landsliding in the catchments we show that the low relief sub catchments above knickpoints erode at uniform background rates of 0 10 mm yr while downstream of knickpoints erosion removes 50 of the rock uplifted by the faults at rates of 0 10 0 64 mm yr despite widespread landsliding crn samples provide relatively consistent and accurate erosion rates most likely because landslides are frequent small and shallow and represent the integrated record of landsliding over several seismic cycles consequently we combine these validated 10be erosion rates and data from a geomorphological landslide inventory in a published numerical model to gain further insight into the long term landslide rates and sediment mixing highlighting the potential of crn data to study landslide dynamics

tectonosedimentary evolution of the deep iberia newfoundland margins evidence for a complex breakup history most of the conceptual ideas concerning sedimentary architecture and tectonic evolution of deep rifted margins are based on either intracontinental rift basins or proximal margins both of which underwent only small amounts of crustal thinning in this paper we investigate the tectonosedimentary and morphotectonic evolution related to continental breakup of the highly extended deep iberia newfoundland margins our results show that continental breakup is a complex process distributed in time and space on the basis of mapping of dated seismic units and borehole data we are able to identify two major phases of extension during a first phase dated as tithonian to barremian 145 128 ma deformation is related to exhumation of mantle rocks basins become younger oceanward and fault geometry changes from upward to downward concave resulting in complex sedimentary structures and basin geometries a second phase dated as latest aptian 112 ma overprints previously exhumed mantle and accreted juvenile oceanic crust over more than 200 km leading to the formation of basement highs the observed complex breakup history challenges classical concepts of rifting and leads to new interpretations for the tectonosedimentary evolution of deep rifted margins

geophysical signatures of oceanic core complexes author posting the authors 2009 this article is posted here by permission of john wiley sons for personal use not for redistribution the definitive version was published in geophysical journal international 178 2009 593 613 doi 10 1111 j 1365 246x 2009 04184 x

spatio temporal patterns of historical shallow landslides in a volcanic area mt aso japan abstract the evaluation of spatially and temporally distributed records of translational shallow landslides in heterogeneous watersheds provides insights needed to understand disastrous processes recurrent slope instability events occurred between 1953 and 1998 in two watersheds of mt aso western japan this paper investigates 1 the spatio temporal characteristics of translational shallow landslides dimensions numbers densities and area subjected to failure observed at a particular location 2 dem based landform characteristics elevation slope angles curvatures and their control on landslide distribution and 3 rainfall characteristics the evaluation of the landslide history consequences and characteristics of spatially and temporally distributed landslides are based on the series of inventory maps for years 1954 1977 1990 and 1998 geologically the watersheds consist of pyroxene olivine andesite basalt lava pyroclastics deposits gravel sand and clay deposits originated from takadake nekodake and washigamine volcanoes during 45 years 1953 1998 a total of 619 and 976 numbers of shallow landslides have been recognized in the sakurakigawa and furuegawa watersheds respectively repeated sliding denuded a total surface area of 0 372 km 2 in the sakurakigawa watershed representing 35 of the watershed area similarly slides denuded a total of 0 534 km 2 in the furuegawa watershed representing 12 of the watershed area for example storm events of june 1953 and july 1990 with rainfall intensities of 49 and 61 mm h 1 respectively triggered numerous landslides about 25 and 47 of sakurakigawa and furuegawa watersheds respectively still bears the potential to produce landslides landslides were commonly observed where thick unconsolidated tephra layers and pyroclastics rocks overlain by thin tephra bed existed and for a slope inclination range of 30 35

movement along a low angle normal fault the s reflector west of spain 1 the existence of normal faults that moved at low angles less than 20 has long been debated one possible low angle fault is the s detachment at the west galicia spain margin and thought to occur at the top of serpentinized mantle it is unlikely that s was a large submarine slide as it was probably active over several million years without the development of any compressional features such as toe thrusts it appears to have rooted beneath the conjugate flemish cap margin and it is similar to structures elsewhere that also appear to be rooted detachments here we analyze depth images to identify synrift sediment packages above s and use the geometry of these synrift packages to constrain the angle at which s both formed and remained active we find that s must have remained active at angles below 15 too low to be explained simply by the low friction coefficient of partially serpentinized peridotites instead we suggest that transient high fluid pressures must have developed within the serpentinites and propose a model in which anastomosing fault strands are alternately active and sealed enabling moderately high fluid pressures to develop