crystallization environment of kazakhstan microdiamond evidence from nanometric inclusions and mineral associations nanometric solid inclusions in diamond incorporated in garnet and zircon from felsic gneiss of the kokchetav massif kazakhstan have been examined utilizing electron microscopy and focused ion beam techniques host garnet and zircon contain numerous pockets of multiple inclusions which consist of 1 3 diamond crystals intergrown with quartz phengite phlogopite albite k feldspar rutile apatite titanite biotite chlorite and graphite in various combinations recalculation of the average chemical composition of the entrapped fluid represented by multiple inclusion pockets indicates that such fluid contained a low wt of sio2 suggesting a relatively low temperature fluid rather than a melt transmission electron microscopy revealed that the diamond contains abundant nanocrystalline inclusions of oxides rare carbonates and silicates within the 15 diamond crystals studied abundant inclusions were found of sio2 tio2 f e xoy c r 2o3 zrsio4 and single grains of thxoy baso4 mgco3 fecr2o4 and a stoichiometric fe rich pyroxene the diversity of trace elements within inclusions of essentially the same stoichiometry suggests that the kokchetav diamond crystallized from a fluid containing variable amounts of si fe ti cr zr ba mg and th and other minor components such as k na p s pb zn nb al ca cl most of the components in crystals included in diamond appear to have their origin in the subducted metasediments but some of them probably originate from the mantle it is concluded that kokchetav diamond most likely crystallized from a coh rich multicomponent supercritical fluid at a relatively low temperature hence the apparently low content of rock forming elements and that the diversity of major and minor components suggests interactions between subducted metasediments and mantle components

a multi method monitoring of timing magnitude and origin of rockfall activity in the japanese alps abstract a multi method monitoring was conducted to detect the timing and trigger of rockfall activity on an alpine rockslide cliff composed of cretaceous sandstone and shale in the southern japanese alps aresawa rockslide 2900 m above sea level the monitoring programme includes manual measurements of flaking from painted rock surface and collection of fallen debris daily time lapse imaging of the rockwall automated recordings of rock temperature rock moisture and influencing meteorological factors air temperature and precipitation a stereographic pair of sequential photographs is used to visually identify the location of new erosion and semi quantitative evaluation of detached materials at daily resolution six years 2010 2016 of debris trapping show major rockfall activity in winter between november and may and occasional activity associated with heavy rains in summer and yield an average rate of rockwall retreat on the order of 1 mm a 1 the rockwall shows heterogeneous debris production mainly reflecting joint spacing time lapse imaging displays at least 10 15 rockfall events per year within the shot area 500 m2 the integration of multiple data suggests at least five types of triggering processes towards rockfalls which recur annually 1 in summer and early autumn heavy rainfalls raise the moisture content of the shallow bedrock often triggering significant rockfalls probably due to raised water pressure in rock joints or lubrication of joints 2 in late autumn and late spring light or intermediate rainfalls are sometimes followed by high moisture shallow freezing rapid thawing and eventually by different scales of rockfalls 3 in winter and early spring the same process as in the second case but rainfall is replaced by snowfall triggers submeter scale rockfalls 4 deep seasonal freezing to about 5 m enables release of meter scale rockfalls during seasonal thawing periods from late spring to early summer 5 short term large thermal fluctuations that produce cyclic thermal stress may also contribute to submeter scale rockfalls mainly in winter locally enhanced by freeze thaw action

coesite and pure pyrope in high grade blueschists of the western alps a first record and some consequences a pyrope quartzite originally described by vialon 1966 from the dora maira massif was resampled and reinvestigated garnet up to 25 cm in size phengite kyanite talc and rutile are in textural equilibrium in an undeformed matrix of polygonal quartz the garnet is a pyrope almandine solid solution with 90 to 98 mol mg end member it contains inclusions of coesite which has partially inverted to quartz resulting in a typical radial cracking of the host garnet around the inclusions several lines of evidence show that coesite crystallised under nearly static pressure conditions and that the whole matrix has once been coesite

mineral inclusions in zircons of para and orthogneiss from pre pilot drillhole ccsd pp1 chinese continental scientific drilling project the pre pilot drillhole ccsd pp1 chinese continental scientific drilling project ccsd with depth of 432 m is located in the donghai area in the southwestern sulu terrane the core samples are mainly comprised of paragneiss orthogneiss and ultramafic rock with minor intercalated layers of eclogite and phengite bearing kyanite quartzite all analyzed paragneiss and orthogneiss samples were overprinted on amphibolite facies retrograde metamorphism coesite and coesite bearing ultrahigh pressure uhp mineral assemblages were identified by raman spectroscopy and electron microprobe analysis as inclusions in zircons separated from paragneiss eclogite and phengite bearing kyanite quartzite samples in the paragneiss samples uhp mineral inclusion assemblages mainly consist of coe omp grt phe coe jd phe ap preserved in the mantles m and rims r of zircons these uhp mineral inclusion assemblages yield temperatures of 814 852 c and pressures of 28 kbar presenting the p t condition of uhp peak metamorphism of these country rocks according to the mineral inclusions and cathodoluminescence images of zircons the orthogneisses can be divided into two types uhp og1 and non uhp og2 in og1 orthogneisses low pressure mineral inclusion assemblage mainly consisting of qtz phe ab ksp ap were identified in zircon cores c while coesite or coesite bearing uhp mineral inclusions were identified in the mantles m and rims r of the same zircons these features suggest that the og1 orthogneisses together with the paragneisses phengite bearing kyanite quartzite and eclogite experienced widespread uhp metamorphism in the sulu terrane however in the zircons of og2 orthogneiss samples no uhp mineral inclusions were found inclusions mainly comprised qtz phe ap and were identified in cores c mantles m and rims r of og2 zircons the cathdoluminescence images of all analyzed zircons showed clear zonings from cores to rims these features indicate that the og2 orthogneisses in pre pilot drillhole ccsd pp1 did not experience uhp metamorphism therefore we should not rule out the possibility that some orthogneisses in sulu terrane might represent relatively low pressure granitic intrusives emplaced after the uhp event

long term gravitational deformation of rocks by mass rock creep abstract subsurface rocks beneath slopes are deformed to various degrees in various ways by mass rock creep mrc when they are subjected to a gravitationally unstable state for a long period mrc forms folds faults and numerous kinds of fractures such deformation is one of the main factors for deteriorating rock masses on slopes and also precursors of many landslides mrc deformations which have often been ascribed to tectonic origins can be distinguished from tectonic ones by their deformational features landforms and relationships between slope morphology and subsurface structures mrc folds are flexural slip folds that have the following mesoscopic to microscopic characteristics their axial surfaces are not smooth but are jagged and many visible openings or open fractures develop in association with the folds the jagged axial surfaces become smoother at depth and openings decrease in width with increasing overburden at the deformation site macroscopic types of mrc folds change according to the relationship between foliations and slopes buckling folds form in consequent slopes drag folds form in a deeper part of obsequent slopes and bending folds form in slopes with steep dipping foliations consequent or obsequent by downslope bowing of foliations shear fractures and tension fractures are the main deformational structures formed by mrc in massive rocks among shear fractures those of listric origin are remarkable tension fractures in general occur either in networks dividing rocks into fragments that slip and rotate irregularly in relation to each other or in parallel arrays of steeply dipping fractures an mrc fault has a shear zone consisting of a pulverized zone with gouge and a phyllitic or brecciated zone in a densely foliated rock the phyllitic zone is formed by microscopic slip along foliations in a sparsely foliated rock the brecciated zone is formed by random crushing except for the faults made through the shear fractures in massive rocks landforms due to mrc are gentle slopes bounded by horseshoe knicklines upslope convex slopes ridge top depressions multiple ridges uphill facing scarps and ridge crossing depressions

microdiamond daughter crystals precipitated from supercritical coh silicate fluids included in garnet erzgebirge germany microdiamonds associated with phlogopite quartz paragonite phengite apatite and rutile are found as regular constituents of minute polyphase inclusions in garnet of ultrahigh pressure p metamorphic gneiss lenses within migmatites of the gneiss eclogite unit erzgebirge germany these aggregates are interpreted to represent original inclusions of a supercritical dense coh fluid rich in k na and sio 2 from this fluid diamond was precipitated as a daughter crystal due to cooling at ultrahigh p conditions brittle failure of the garnet host due to overpressure during release of confining pressure is demonstrated by healed radial cracks during further cooling the silicate phase assemblage of the inclusions crystallized at reduced internal pressures outside the stability field of diamond as indicated by the presence of quartz paragonite and plagioclase it is proposed that the mica dominated mineral assemblage of the inclusions formed by reaction between the fluid and the garnet host the previously formed diamond daughter crystals being preserved metastably these diamond bearing inclusions provide an unequivocal record of dense supercritical coh fluids rich in alkalies and silica within subducted continental crust during ultrahigh p metamorphism

hadean diamonds in zircon from jack hills western australia this paper reports the discovery of micro diamond inclusions in zircon from the jack hills western australia which is up to 4 252 million years old and includes the oldest known diamonds found in terrestrial rocks the spread of ages indicates that either the conditions required for diamond formation were repeated several times during early earth history or that there was significant recycling of ancient diamond

evolution of host inclusion systems a visco elastic model a visco elastic model is suggested to recover the p t t paths of spherically symmetrical host inclusion systems from residual pressure patterns for a coesite garnet aragonite garnet and diamond garnet system with partial transition of high pressure polymorphs to low pressure ones the model predicts that the exhumation history of ultra high pressure metamorphic rocks from depths below 90 km began with pressure decrease to 1 gpa 40 km depth while the temperature remained high 800 c then the system cooled and decompressed to ambient conditions non spherical inclusion shapes in the 3 d model lead to heterogeneities in residual pressure and shear stress distributions as well as to significant gradients of shear stress which may affect the kinetics and thermodynamics of phase transformation in the inclusions

rock slope instability and erosion toward improved process understanding rock slopes in a range of environments are among the landscape elements most sensitive to climate change the latter affecting rock mass properties altering slope boundary conditions and changing geosystem configurations major climate dependent influences promoting destabilization include stress redistribution with changing glacial ice extents degradation of mountain permafrost altered slope hydrology and weathering environments loading and unloading due to deposition and erosion and changes in the spectrum of magnitude and frequency of driving forces in steep bedrock terrain erosional processes control slope morphology by modulating rates of i weathering in response to climate and pre disposition ii rock slope retreat in response to magnitude and frequency of detachment and iii channel incision or valley infilling in response to variable sediment supply modelling landscape evolution and anticipating natural hazards in these environments thus requires deeper insights into the processes driving rock slope instability and erosion this special issue emphasizes new understanding of rock slope processes through a collection of manuscripts at the forefront of research in the field copyright 2014 john wiley sons ltd

discrete element modeling of the mass movement and loose material supplying the gully process of a debris avalanche in the bayi gully southwest china abstract the dynamic process of a debris avalanche in mountainous areas is influenced by the landslide volume topographical conditions mass material composition mechanical properties and other factors a good understanding of the mass movement and loose material supplying the gully process is very important for understanding the dynamic properties of debris avalanches three dimensional particle flow code pfc3d was used to simulate a debris avalanche in quaternary deposits at the bayi gully southwest china fortran and autocad were used for the secondary development to display the mass movement process and to quantitatively describe the mass movement and loose material supplying the gully process the simulated results show that after the landslide is initiated the gravitational potential energy is converted into kinetic energy with a variation velocity for the sliding masses two stages exist for the average movement velocity the acceleration stage and the slowdown stage which are influenced by the topographical conditions for the loose materials supplying the gully process the cumulative volume of the sliding masses into the gully gradually increases over the time when the landslide volume is not large enough the increasing landslide volume does not obviously influence the movement process of the sliding masses the travel distance and movement velocity increase with the decreasing numerical parameters and the mass movement process is finished more quickly using low value parameters the deposition area of the sliding masses decreases with the increasing numerical parameters and the corresponding deposition thickness increases the mass movement of the debris avalanche is not only influenced by the mechanical parameters but is also controlled by the topographical conditions

diamond graphite relationships in ultrahigh pressure metamorphic rocks from the kokchetav massif northern kazakhstan graphite inclusions in diamond k bearing clinopyroxene garnet and kyanite and graphite coatings around microdiamonds from the ultrahigh pressure kokchetav massif northern kazakhstan were investigated by means of scanning electron microscopy laser raman spectroscopy and x ray diffraction important observations include the increasing size of the graphite crystals from the diamond graphite interface to the external part of the graphite coatings the high volume fraction of graphite in the graphite coatings the presence of composite crystals of successively formed diamond core graphite mantle zone diamond rim external graphite coating the spherulitic texture of the graphite coatings the formation of both ordered and disordered graphite and the absence of any fluid associated with the graphite inclusions in diamond and other ultrahigh pressure metamorphic uhpm minerals these features combined with the presence of oriented graphite flakes in k bearing clinopyroxene and in diamond bearing garnet and kyanite and the presence of intergranular diamonds without graphite coatings in the quartzo feldspathic matrix require reconsideration of the generally accepted diamond graphitization model for interpreting the formation of graphite in uhpm rocks metastable growth of graphite within the diamond stability field is suggested and the following crystallization scheme for the c polymorph is proposed graphite was the first c polymorph formed in the diamond stability field followed by diamond the graphite coatings around diamond formed during the final stage of uhpm conditions

two stage growth of microdiamond in uhp dolomite marble from kokchetav massif kazakhstan the abundance and morphology of microdiamond in dolomite marble from kumdy kol in the kokchetav massif are unusual a previous study estimated the maximum content of diamonds in dolomite marble to be about 2700 carat ton 1 microdiamond is included primarily in garnet and occasionally in diopside and phlogopite pseudomorphs after garnet they are classified into three types on the basis of their morphology 1 s type star shaped diamond consisting of translucent cores and transparent subhedral to euhedral very fine grained outer parts 2 r type translucent crystals with rugged surfaces and 3 t type transparent very fine grained crystals the s type is the most abundant micro laue diffraction using a 1 6 m x ray beam size demonstrated that the cores of the star shaped microdiamond represent single crystals in contrast the most fine grained outer parts usually have different orientations compared to the core laser raman studies indicate that the fwhm full width at half maximum of the raman band of the core of the s type diamond is slightly larger than that for the outer parts differences in morphology crystal orientations and in the fwhm of the raman band between the core and the fine grained outer parts of s type microdiamond suggest that the star shaped microdiamond was formed discontinuously in two distinct stages

raman spectroscopic and microscopic criteria for the distinction of microdiamonds in ultrahigh pressure metamorphic rocks from diamonds in sample preparation materials natural diamond from three ultrahigh pressure metamorphic uhpm terranes erzgebirge massif germany kokchetav massif northern kazakhstan rhodope metamorphic province greece and synthetic diamond from cutting and polishing materials paste spray saw blade were studied by means of optical microscopy and raman microspectroscopy to constitute a new petrographic and spectroscopic data set that might be a useful tool for identifying and characterizing metamorphic diamond several criteria are established for distinguishing natural microdiamond identified in a rock thin section from the externally introduced ones i e diamond as residual particles contaminants from the cutting and polishing material such as the diamond size the presence of inclusions coatings or coexistent phases and two diamond raman band parameters i e the raman shift and the full width at half maximum height fwhm

examples of multiple rock slope collapses from kofels otz valley austria and western norway abstract this paper describes the effects of large massive rock slope failures on subsequent slope stability three examples of large rock slope failures from the austrian alps and norway demonstrate that failure increases the probability of further collapses at kofels austria a holocene rock slope failure several km3 in size filled the otz valley the morphology of the deposits indicates that at least one subsequent failure occurred along the head scarp of the first failure most likely a slide of similar size debris of the second landslide slid over the older deposits forming the famous kofels frictionite at least three rock slope failures all of them in excess of 106 m3 occurred from the same mountainside within the last 6000 8000 years at tafjord in western norway the most recent of these failures in 1934 triggered a destructive tsunami five large failures with volumes 50 000m3 occurred at ramnefjell norway within 50 years two of them caused considerable damage and a large number of death due to the formation of destructive tsunamis two dimensional finite element models of rock slope stability before and after the kofels and tafjord landslides show that massive rock slope failures produce a irregular slopes parts of which are as steep or steeper than the slope before failure and which represent new zones of instability and b zones of weakness related to slow slope deformation and related cracking

erratum to metamictisation of natural zircon accumulation versus thermal annealing of radioactivity induced damage annealing of the radiation damage generated in decay events is a common phenomenon in natural zircons we have studied relationships between radiation damage age and radionuclide content of natural zircons on a micro scale the degree of metamictisation was estimated by means of confocal laser raman spectroscopic measurements raman band broadening in well ordered to moderately metamict zircons that have not experienced significant healing of the radiation damage since the time of their growth shows a nearly linear dependence on the fluence this dependence is proposed as a calibration line for examining unknown zircons in order to consider complete or incomplete damage storage which may contribute to the understanding of the low t thermal history of their host rocks seven examples for the application are presented radiation damage may anneal heterogeneously with preferred re ordering in more damaged micro areas results suggest that single point defects do not anneal continuously over geologic periods of time but are in contrast a comparably stable type of radiation damage in contrast to recrystallisation processes structural recovery due to simple thermal annealing is not necessarily connected with loss of radiogenic pb the most prominent example for this are concordant zircons from sri lanka although they are excellent standards for u pb dating sri lankan zircons should not be used as standards for structural radiation damage the experimental work is completed by monte carlo simulations of decay events in zircon

structural constraints on deep seated slope deformation kinematics abstract a significant sackung type deep seated slope gravitational deformation dsgsd was recognised for the first time by the authors in the middle part of valfurva east of bormio rhaetian alps italy the reconstruction of its kinematics age and state of activity is presented through a detailed description of its morphological geomechanical and structural features an integrated multi disciplinary approach was performed to achieve a clear comprehension of the phenomenon field surveys and aero photo interpretation were carried out in order to clarify the structural geological and geomorphological setting in which the dsgsd developed a kinematic conceptual model of the slope deformation was developed through the analysis of morpho structures of their significance and relationships with lithological markers and quaternary deposits after a geomechanical characterisation of the rock mass involved in the slope deformation numerical modelling was performed to verify the hypotheses made on kinematics and driving factors of the phenomenon the sackung affects pre permian metapelites metabasites and marbles belonging to the upper austroalpine basement of the campo nappe as well as late pleistocene and holocene glacial and rock glacier deposits the deformation started after the late wurmian age 15 000 11 000 years b p and continued until few centuries ago not excluding a present day low rate activity deformation consists in a large oblique sagging along a deep confined sliding surface associated with gravitational reactivation of pre existing late alpine and recent tectonic brittle structures leading to the formation of n s and wnw ese trending gravitational morpho structures the evolution of the wnw ese trending system resulting in asymmetric trenches led to progressive failure of the lower part of the slope during the last 10 000 years as testified by large paleo landslide accumulations and it is still in progress numerical modelling indicates post glacial unloading as the main triggering factor of the slope deformation the importance of this deep seated slope deformation is enhanced by the occurrence of the 30 mm 3 active ruinon landslide in the lower part of the slope such landslide is subjected to rapid evolution and threatens the valley floor establishing an important risk factor connected to human lives and socio economic activities

coesite in clinopyroxene in the caledonides and its implications for geodynamics coesite is reported for the first time from the caledonide orogen it occurs as inclusions in clinopyroxene in the dolomite eclogite at grytting norway and provides valuable new evidence to support the hypothesis of extremely high pressure 30 kbar in certain norwegian eclogites this finding has implications for the geodynamics and kinetics of the concepts of microscale intracrystalline tectonic overpressure and of macroscale local or regional tectonic overpressure and for the hypotheses of subduction and obduction involving a more than 100km vertical component of transport

discovery of metamorphic diamonds in central china an indication of a 4000 km long zone of deep subduction resulting from multiple continental collisions the central orogenic belt cob of china is a major continental collision zone that contains extensive outcrops of deeply subducted and exhumed rocks at both the eastern and the western end of the belt here we report discovery of microdiamonds from both eclogites and felsic gneisses in the north qinling zone in the central portion of the cob this discovery demonstrates that the country rocks of continental affinity shared in the ultra high pressure metamorphic uhpm event and provides a bridge connecting the two previously recognized uhpm terranes thereby establishing the existence of a uhpm belt extending more than 4000 km geochronological dating yields early palaeozoic ages in the west and early mesozoic ages in the east recording two separate continental collisions overprinted within the cob occurrence of uhp metamorphism during recurrent continental collision here and in the alps suggests that deep subduction of continental material during such collisions is probably common rather than exceptional with significant implications for processes of plate tectonic reorganization and mantle mixing over time

holocene rockwall retreat in svalbard a triple rate evolution volumetric calculations of slope deposits direct measurements of rockwall retreat and chronological control based on lichenometry provide a wide range of rockwall retreat rates in svalbard 0 1580 mm ka 1 that appears consistent with previous evaluations from other arctic areas in northwest and central spitsbergen 79 n a triple rate rockwall retreat is suggested for the last two millennia very slow biogenic flaking 2 mm ka 1 moderate retreat due to frost shattering 100 ka 1 and rapid retreat associated with post glacial stress relaxation c 1000 mm ka 1 examination of the distribution of various processes indicates that the holocene retreat of most rockwalls has not exceeded one or two metres bedrock conditions appear to be the main control on retreat rates the massiveness of igneous and metamorphic outcrops widespread in arctic shield areas largely accounts for the slowness of rockwall retreat which on these lithologies is primarily due to chemical and biological processes more rapid rates are usually associated with stress relaxation following glacial surges or with local frost susceptibility of bedrock often where faulting has induced high joint density at such sites rockwall retreat rates are of the same order of magnitude as those reported from alpine areas 1000 3000 mm ka 1 where both bedrock weakening due to tectonic stresses and the greater height of steep rockwalls account for the more rapid rockwall retreat rate 1997 by john wiley sons ltd

microdiamond in high grade metamorphic rocks of the western gneiss region norway three grains of microdiamond were recovered from high grade gneiss exposed in the western gneiss region norway identification and characterization of the diamond grains by raman and infrared spectroscopy indicate the presence of substitutional impurities of h and n primary fluid inclusions in garnet and quartz in the diamond bearing rock demonstrate the evolution of metamorphic volatile fluids from reduced n 2 co 2 compositions during the peak phase of metamorphism to n 2 ch 4 h 2 o bearing compositions during retrograde metamorphism compatible geologic petrologic and fluid composition data imply a metamorphic origin for the microdiamonds if so the metamorphic and fluid conditions recorded by the microdiamonds and gneissic host may be applicable to microdiamond investigations in other high pressure regionally metamorphosed orogens

seismic signatures of landslides the 1990 brenda mine collapse and the 1965 hope rockslides abstract we present the well documented case of a 2 10 6 m 3 rockslide that was recorded by seismographs to distances of several hundred kilometers and might have entered the canadian catalog as a bona fide earthquake except for independent knowledge to the contrary motivated by the observation of this event we reexamined the seismograms associated with the 1965 hope slide in british columbia the largest known historical landslide in the canadian cordillera and conclude that these seismograms were the signatures of two rockslides and not of hypothetical tectonic earthquake triggers as previously suggested mathews and mctaggart 1969 wetmiller and evans 1989 these events raise the general question of differentiation between seismic signals from landslides and true earthquakes we suggest an lp sp discriminant as the most obvious although a resolvable mechanism solution may be even more convincing efficiency of energy conversion from potential to seismic is also a diagnostic aid and correlates well with the slope of the slide detachment surface

seismic monitoring of sechilienne rockslide french alps analysis of seismic signals and their correlation with rainfalls 1 in the french alps sechilienne rockslide is one of the natural phenomena that presents one of the highest levels of risk in terms of socioeconomical outcomes this rockslide has been active for a few decades and has been instrumented since 1985 the current very active volume of this rockslide is estimated to be up to 5 million m3 located on the border of a slowly moving mass reaching 50 100 million m3 the velocity of the most active zone reached 1 4 m yr in 2008 about twice the value of 2000 a seismic network was installed on this rockslide in may 2007 to supplement the monitoring system it has now recorded several thousand events mostly rockfalls but also hundreds of local and regional earthquakes which can be distinguished and classified from their signal characteristics rockfalls and microseismicity which occur in bursts of activity are found to be weakly but significantly correlated with rainfall rockfall occurrence increases linearly with precipitation with however strong fluctuations of the numbers of rockfalls per day for the same rainfall intensity no threshold was found for rainfall triggering with even 1 mm of rain being enough to trigger rockfalls rockfall activity starts almost immediately during a rainfall episode and lasts for several days after the rainfall rain also induces strong accelerations of the rockslide movement which also start quasi instantaneously and last for about a month

discovery of metamorphic microdiamonds from the parautochthonous units of the variscan french massif central the variscan french massif central fmc is classically described as a stack of nappes with increasing metamorphism from the bottom parautochthonous unit to the top lower and upper gneiss units ultra high pressure uhp metamorphism was already recognized in the uppermost units with notably coesite bearing rocks we report the first finding of metamorphic microdiamonds in the parautochthonous unit revealing that the uhp event affected the whole stack of nappes and also that the pressures reached are above what was previously expected since the presence of diamond according to the peak temperature estimates for this unit indicates pressures of ca 3 gpa i e 100 km depth at the scale of the fmc this finding adds complexity to the established models on a broader scale this adds evidence of similarity between this part of the belt and other uhp variscan terranes such as the erzgebirge and the bohemian massif

significance of rockfall magnitude and carbonate dissolution for rock slope erosion and geomorphic work on alpine limestone cliffs reintal german alps abstract the proportional contribution of low mid and high magnitude rock slope failure orchestrates rock slope erosion and rockfall hazard in alpine and arctic environments in this study we compare sediment yield geomorphic work and rock wall retreat of carbonate dissolution and five different magnitudes of rock slope failure in the steep alpine reintal trough valley we combine a four year rockfall collector measurement of 140 mg of fragmental rockfall a 20th century scientific record of mid magnitude rockfall as well as carbon dating and a historical record of 15th to 19th century rock avalanche activity the total rockfall sediment yield of 8 6 3 4 10 3 m 3 year 1 is dominated by high magnitude rock avalanches 10 6 m 3 62 and low magnitude debris falls 3 18 while mid magnitude boulder block and cliff falls are less important the magnitude signal contradicts studies on siliceous rocks where mid magnitude rockfall dominates rock slope erosion the geomorphic work released in the 17 3 km 2 large catchment by rockfalls 123 47 w km 2 i e 0 38 0 15 mm year 1 and solute transport 34 18 w km 2 i e 0 05 0 03 mm year 1 exceeds previously published alpine values by one to multiple orders of magnitude we hypothesise that the magnitude signal of enhanced small and high magnitude rockfall is characteristic for carbonate cliffs the elevated porosity related susceptibility to fragmentation and persistent carbonate dissolution along potential sliding planes are likely to favour both low and high magnitude rock slope failures here we show how the magnitude signal of rock slope failure influences rock wall retreat geomorphic work rockfall deposition and sediment connectivity

zircon response to diamond pressure metamorphism in the kokchetav massif ussr ultrahigh pressure metamorphism of the diamond bearing gneisses in the kokchetav massif ussr has been dated at 530 7 ma 2 sgr by shrimp ion microprobe analysis of metamorphic zircons zircon xenocrysts as old as 2000 ma have retained original isotopic compositions through the extreme metamorphic conditions and indicate that the protolith that was buried to diamond forming pressures included early proterozoic components highly variable reset ting of u pb isotopic systems in zircon xenocrysts at the time of metamorphism suggests that diffusive lead loss had commenced but was incomplete a disequilibrium observation consistent with relatively transient exposure of the rocks to extreme crustal depths

kinematics of an alpine retrogressive rockslide in the japanese alps the aresawa rockslide in the japanese alps experienced a partial collapse 5 10 105 m3 in 2004 followed by an accelerated downward movement of the head area rather than stabilization this paper discusses the kinematics of a retrogressive rockslide area and factors promoting slope instability subsequent to the 2004 collapse on the basis of geodetic surveys and meteorological observations from 2006 to 2010 the unstable area covers at least 2 3 104 m2 and consists of five active blocks the main blocks are separated from the stable rock slope by pre existing sackung features that follow the strike of the bedding plane shear zones below these sackung features have developed into slip planes potentially causing the next collapse in particular the propagation of a slip plane causing movement at 70 cm yr 1 in the head area is promoted by bidirectional movement it consists of slow dip slip movement in snow accumulating periods and rapid side slip movement in snow melting and snow free periods both of which occur on the same slip plane this bidirectional movement appears to result from the combination of a loss of lateral support by the 2004 event and the immature state of the slip plane the primary trigger of the acceleration in the unstable area is the stress release by the 2004 collapse in addition the presence of a potential slip plane below the sackung features also promotes slope instability suggesting that sackung features behind a rockslide area may predefine the new head scarp of a forthcoming collapse copyright 2012 john wiley sons ltd

a comparison of the evolution of diamondiferous quartz rich rocks from the saxonian erzgebirge and the kokchetav massif are so called diamondiferous gneisses magmatic rocks abstract the petrography and chemical composition of minerals of quartz rich diamondiferous rocks from the kokchetav massif especially the zonation of garnet were studied and compared with diamondiferous quartzofeldspathic rocks from the saxonian erzgebirge many compositional and textural features were found to be similar for instance microdiamonds are enclosed systematically in a specific intermediate growth zone of garnet in these rocks on the basis of experimental data a magmatic scenario was constructed to check if the quartz rich diamondiferous rocks are of magmatic origin by this the p t paths derived here for the kokchetav rocks and the textural observations it is concluded that the minerals of the diamondiferous rocks have crystallized from silicate melts these melts originated by anatexis of deeply submerged metasediments erzgebirge at t as high as 1200 c kokchetav massif at 50 100 c lower t and ascended from at least 200 km depth relics of the pre anatectic evolution are still present for instance as garnet cores after ascent and emplacement of the magma in deep portions of thickened continental crust kokchetav massif 45 50 km close to 800 c erzgebirge 55 60 km at 30 50 c lower t considerable quantities of white and or dark micas formed by peritectic reactions from melt for instance garnets could be resorbed at this stage and biotite grew instead after the magmatic stage retrogression took place much stronger in the kokchetav massif this was accompanied by deformation transforming broadly the magmatic texture of quartz rich diamondiferous rocks from the kokchetav massif to a gneissic texture

metamorphic evolution of diamond bearing and associated rocks from the kokchetav massif northern kazakhstan representative diamond bearing gneisses and dolomitic marble eclogite and ti clinohumite bearing garnet peridotite from unit i at kumdy kol and whiteschist from unit ii at kulet eastern kokchetav massif northern kazakhstan were studied diamond bearing gneisses contain variable assemblages including grt bt qtz pl kfs zo chl tur cal and minor ap rt and zrn abundant inclusions of diamond graphite chlorite or calcite phengite clinopyroxene k feldspar biotite rutile titanite calcite and zircon occur in garnet diamond bearing dolomitic marbles consist of dol di grt phl inclusions of diamond dolomite graphite biotite and clinopyroxene were identified in garnet whiteschists carry the assemblage ky tlc grt rt garnet shows compositional zoning and contains abundant inclusions of talc kyanite and rutile with minor phlogopite chlorite margarite and zoisite inclusions and zoning patterns of garnet delineate the prograde p t path inclusions of quartz pseudomorphs after coesite were identified in garnet from both eclogite and gneiss other ultrahigh pressure uhp indicators include na bearing garnet up to 0 14 wt na2o with omphacitic cpx in eclogite occurrence of high k diopside up to 1 56 wt k2o and phlogopite in diamond bearing dolomitic marble and cr bearing kyanite in whiteschist these uhp rocks exhibit at least three stages of metamorphic recrystallization the fe mg partitioning between clinopyroxene and garnet yields a peak temperature of 800 1000 c at p 40 kbar for diamond bearing rocks and about 740 780 c at 28 35 kbar for eclogite whiteschist and ti bearing garnet peridotite the formation of symplectitic plagioclase amphibole after clinopyroxene and replacement of garnet by biotite amphibole or plagioclase mark retrograde amphibolite facies recrystallization at 650 680 c and pressure less than about 10 kbar the exsolution of calcite from dolomite and development of matrix chlorite and actinolite imply an even lower grade greenschist facies overprint at c 420 c and 2 3 kbar a clockwise p t path suggests that supracrustal sediments together with basaltic and ultramafic lenses apparently were subjected to uhp subduction zone metamorphism within the diamond stability field tectonic mixing may have occurred prior to uhp metamorphism at mantle depths during subsequent exhumation and juxtaposition of many other tectonic units intense deformation chaotically mixed and mylonitized these lithotectonic assemblages

diamond former coesite and supersilicic garnet in metasedimentary rocks from the greek rhodope a new ultrahigh pressure metamorphic province established abstract we report here the first discovery of ultrahigh pressure uhp indicator minerals and textures from the rhodope metamorphic province rmp northern greece in particular we document the exsolution of quartz rutile and apatite in sodic garnet from metapelites garnet biotite kyanite gneisses which attests to the presence of a si ti na p rich precursor garnet phase similar textures in garnet have been reported in the literature only once before for eclogites from the su lu uhp metamorphic province china we also document the presence of microdiamonds and multicrystalline quartz pseudomorphs after coesite included in garnet from both eclogites and metapelites we then argue that these rocks had once been transported to depths exceeding 220 km well into the upper mantle thus establishing the rmp as another important uhp metamorphic belt in the world

deep seated rockslide avalanches preceded by mass rock creep of sedimentary rocks in the akaishi mountains central japan abstract seven large rockslide avalanches of sedimentary rocks are known in japan almost all of these major landslides were preceded by gravitational deformation of rocks mass rock creep mrc as inferred from geologic and geomorphic investigations of five rockslide avalanches in the akaishi mountains the mrc that preceded the rockslide avalanches in the akaishi mountains was characterized by a slow but steady downslope bowing of steeply dipping foliations which accompanied intensive deformation and fragmentation of the rock mass by shearing along foliations this deformation and fragmentation of the rock mass provides a basic cause for the occurrence of rockslide avalanches which occur when a creeping rock mass has lost its support from the lower part of a slope by stream erosion this type of mrc continues for a long time after a part of the creeping area has slid and results in longterm generation of debris by the landslide sear of the rockslide avalanche

diamond and coesite discovered in saxony type granulite solution to the variscan garnet peridotite enigma diamond and coesite were discovered in situ as inclusions in garnet kyanite and zircon in high pressure granulites from northern bohemian massif these continental crustal rocks were therefore subducted to depths of c 140 km which also explains their common association with mantle garnet bearing peridotites models involving crustal thickening for these high pressure granulites need to be significantly modified whole variscan belt with numerous hp granulite occurrences can represent a large ultrahigh pressure terrain

are sackungen diagnostic features of de glaciated mountains abstract deep seated gravitational slope deformations dsgsds with characteristic sackung landforms e g double crests trenches uphill facing scarps and toe bulging are considered by some researchers to be diagnostic features indicating past mountain glaciations however an extensive literature review on sackung features throughout the world reveals that in some regions paraglacial processes are not the causes of such phenomena sackungen occur across a diverse spectrum of mountain types with different morphoclimatic histories including regions that have never experienced glaciation to reinforce that sackungen may originate independently of glaciation we also include two case studies from the western carpathians czech republic and slovakia which are supported by detailed geomorphic mapping trenching and absolute dating 10 be 14 c and osl on the ond ejnik ridge outer western carpathians czech republic sackungen occur in the mid holocene in the medium high mountains which are beyond the pleistocene glacial limits on the salatin mt tatra mts slovakia the sackungen which occur in formerly glaciated terrain date between 7 5 and 4 2 ka bp representing a 4 ka time lag after the disappearance of glaciers this suggests that the direct link between the ice retreat and the onset of sackung formation is not obvious even in the case of the once glaciated mountain range although paraglacial stress release is undoubtedly one of the crucial causes of sackung genesis in many mountain regions it is not the only important mechanism therefore despite occurring in numerous de glaciated mountains sackung features cannot be considered as proof of past mountain glaciations e g during analysis of extra terrestrial settings

evidence of fluid inclusions in metamorphic microdiamonds from the kokchetav massif northern kazakhstan abstract microdiamonds from garnet clinopyroxenites of the kokchetav massif northern kazakhstan and associated alluvial diamonds have been investigated using infrared spectroscopy all diamonds have high nitrogen contents from 747 up to 4488 20 at ppm and are of type ib iaa nitrogen data are consistent with a diamond formation over a narrow temperature range microdiamonds from garnet clinopyroxenites are characterized by water and carbonate inclusions similar to those ocurring in fibrous coated diamonds from kimberlite which suggest that diamonds grew from a c h o fluid in contrast alluvial microdiamonds do not contain any carbonate inclusions and h2o is absent or present in only minor amounts alluvial diamonds are considerably more n rich but have a similar range of nitrogen aggregation states it is suggested that alluvial diamonds belong to a separate diamond population compared with the microdiamonds from garnet clinopyroxenites the kokchetav microdiamonds are distinct from kimberlitic fibrous diamonds in that they contain abundant ib centres have high nitrogen contents and show different populations depending on host rock type these characteristics support a metamorphic origin for the microdiamonds from the uhpm rocks of the kokchetav massif

contribution of deep seated bedrock landslides to erosion of a glaciated basin in southern alaska landslides represent a key component of catchment scale denudation though their relative contribution to the erosion of glaciated basins is not well known bedrock landslide contribution was investigated on the surface of one of eleven glaciers on a glaciated ridge in the chugach st elias range of southern alaska where the debris from four major landslides is easily distinguished from moraines and other supraglacial material a series of aerial and satellite photos from 1972 to 2000 and field observations in 2001 and 2002 indicate that three of four landslides have fallen onto the surface of the glacier since about 1978 the landslides which originated from the steeply dipping 60 70 bedrock walls were deposited onto the glacier in the ablation zone and are currently being transported downstream supraglacially individual glacial valleys with topographic relief of 400 m are cut into highgrade metamorphic rock characterized by a steep north dipping foliation and fractured by numerous large joints measurements of landslide area and average thickness obtained from high resolution survey data indicate a total landslide volume of 2 3 10 5 m 3 this volume suggests a basin averaged erosion rate from landslides of 0 48 mm a 1 an overall basin scale erosion rate of 0 7 to 1 7 mm a 1 can be inferred but depends on the percentage of the totalbasin sediment yield contributed by supraglacial sources a mean rockwall retreat rate of 6 7 mm a 1 is calculated and is considerably higher than published rates which range from 0 04 to 4 0 mm a 1 controls on landslide generation include seismicity freeze thaw processes topography rock strength and debuttressing it is likely all of these factors contribute to failure although the primary controls for the landslides in this study are thought to be rock strength and topography the absence of landslides on ten of the eleven glaciers on this ridge is attributed to landslide magnitude frequency relationships and short temporal scale of this study large volume bedrock landslides 100 000 m 3 may have low frequency occurring less than once in a 55 year time frame copyright 2005 john wiley sons ltd

genesis of microdiamonds from melt and associated multiphase inclusions in garnet of ultrahigh pressure gneiss from erzgebirge germany abstract the common association of microdiamonds with the phase assemblage phlogopite apatite paragonite and quartz containing amorphous na al silicate inclusions as inclusions in garnets of quartzofeldspathic rocks from the saxonian erzgebirge germany was studied by analytical electron microscopy the assemblage implies a precedent melt which coexisted with the microdiamonds before and after entrapment in the garnet host and subsequently crystallized the formation of microdiamonds in this metamorphic rock could be explained by cotectic induced partial melting of a subducted continental slab at about 4 6 gpa and 1000 c as constrained by the occurrence of tio 2 with an pbo 2 type structure at the peak metamorphic conditions and by the catalytic effect of siderophile and chalcophile elements

large sackung along major tectonic features in the central italian alps deep seated gravitational slope deformation sackung is common in alpine mountain belts it is controlled by lithological geomorphological and structural features we describe and discuss five examples of dsgsd along the insubric line periadriatic fault in the central italian alps the five examples are different in morphology size state of activity and distribution and are located along both primary and secondary valleys we demonstrate relations between structural and gravitational features and discuss the possibility that structural has both passive and active roles in sackung development analysis of ps sar data shows that the studied examples are not active today numerical modelling demonstrates the importance of lithological and structural constraints postglacial debuttressing groundwater fluctuations and weathering on sackung triggering and development

comment on diamond former coesite and supersilicic garnet in metasedimentary rocks from the greek rhodope a new ultrahigh pressure metamorphic province established by e d mposkos and d k kostopoulos earth planet sci lett 192 2001 497 506

raman confirmation of microdiamond in the svartberget fe ti type garnet peridotite western gneiss region western norway introductionvestiges of ultra high pressure meta morphism uhpm havebeenfoundincontinental and oceanic rocks of dif ferentorogensworldwide smith 1988 coleman and wang 1995 carswelland compagnoni 2003 indirectuhpmevidencecomesfromtheappli cation of geothermobarometric tech niques lappin and smith 1978 ravna krogh and paquin 2003 ap plied to uhpm mineral assemblagesand directly from mineralogical indi cators such as coesite diamond andmajoritic garnet chopin 1984 smith 1984 sobolev and shatsky 1990 do brzhinetskaya et al 1995 van roer mund and drury 1998 nasdala andmassonne 2000 mposkos andkosto poulos 2001 van roermund et al 2002 godard et al 2003 neverthe less the mechanisms responsible forthe formation preservation and exhu mation of uhpm rocksin orogens arestill not fully understood the volume and spatial distributionof uhpm rocks within uhpm terr anes including the observed contrastin metamorphic grade between rocksthat contain uhpm minerals andadjacent country rocks that do notcontain them have led to di erentexplanations concerning the origin emplacement and preservation ofthese rocks to explain the occur rence volume and areal extent ofuhpm rocks in the western gneissregion wgr the following mecha nisms that assume a continental sub duction scenario have been proposed a the existence of major and orminor post uhpm tectonic contactssuch as nappes and or tectonic mel anges e g lappin and smith 1978 smith 1984 1988 wain 1997 cuth bert et al 2000 terry and robinson 2003 2004 or b the presence of uids and or deformation leading todi erential prograde or retrogradereactions and di erences in reaction kinetics between rock types austr heim et al 1997 cuthbert et al 2000 wain et al 2001 carswell andcuthbert 2003 cuthbert and car swell 2003 hypotheses that do notnecessarily involve continental sub duction may involve local regional tectonic overpressure in rocks smith 1984 mancktelow 1993 petrini and podladchikov 2000 it isconsidered here that the volume andareal extent of uhpm domains withina single metamorphic terrain are thusimportant parameters to determine asthey can modify or identify the loca tions of inferred or observed tectoniccontacts the relations between uidsand uhpm and or the scales atwhich continental crust subductionor tectonic overpressure might act here we report raman data thatcon rm the previously reported butnot proven presence of microdia monds at the svartberget uhpmlocality in the wgr of norway vrijmoed et al 2006 micro diamond con rmation is consistentwith the results of vrijmoed et al 2006 that the volume and arealextent of the northern uhpm domainof the wgr fig 1 are considerablyexpanded eastwards and followingthe reasoning in the paragraph above the new microdiamond nding willput important constraints on themodels described above ultra high pressure metamorphismin the western gneiss regionthe wgr represents a window inthe scandinavian caledonides wherescandian reworked high grade gneis sic rocks of proterozoic age presum ably belonging to the baltic plate are exposed in addition variableamounts of metadolerites amphi abstract

zonal evolution of alaskan stream structure and transport quantified with argo data the alaskan stream as flows west southwestward along the south side of alaska and the aleutian island arc a western boundary current at the northern edge of the north pacific subpolar gyre the argo float array has improved sampling of the gulf of alaska allowing quantification of the as s zonal evolution from 140 w to 175 w geostrophic alongshore transport of the as in the upper 1000 dbar referenced to an assumed level of no motion at 1000 dbar shows little change from east to west however alongshore absolute geostrophic transports in the top 2000 dbar obtained by combining mean absolute 1000 dbar velocities from float displacements with the geostrophic velocity fields generally increase to the west we estimate full depth transports by fitting a barotropic and the first two baroclinic modes calculated from a climatology to the absolute geostrophic velocities in the upper 2000 dbar and applying the velocities from these fits from 2000 dbar to the seafloor flowing west from its formation region at 140 w 145 w the full depth as becomes stronger more barotropic and also narrower once it reaches 160 w with along shore transports increasing from 16 4 4 9 sv 1 sv 106 m3 s 1 at 140 w to 32 6 5 2 sv at 175 w mean concentrations of relatively warm salty oxygen poor and nutrient rich pacific equatorial water pew in the as decrease from 17 8 0 3 to 8 5 0 5 between 140 w and 175 w however the volume transport of pew by the as exhibits little change over the pew density range between these longitudes

raman micro spectroscopy on diamond graphite and other carbon polymorphs from the ultrahigh pressure metamorphic kimi complex of the rhodope metamorphic province ne greece raman micro spectroscopy was applied on carbon inclusions in garnet porphyroblasts from kyanite biotite garnet schists of the rhodope metamorphic province rmp ne greece diamond and cuboids of poorly to highly ordered graphite were identified either as single phase inclusions or as polyphase inclusions along with co2 and or carbonates calcite magnesian calcite questionable raman bands that may be assigned to other c phases nanodiamond lonsdaleite a different c polymorph have been observed the presence of diamond confirms beyond any doubt the ultrahigh pressure uhp metamorphism reported by mposkos and kostopoulos 1 e mposkos d kostopoulos diamond former coesite and supersilisic garnet in metasedimentary rocks from the greek rhodope a new ultrahigh pressure metamorphic province established earth planet sci lett 192 2001 497 506 in the rmp cuboid graphite showing variable degree of disordering most probably formed after diamond the possible involvement of co2 and or c o h fluids in the formation of diamond is discussed

diamond inclusions in garnets from metamorphic rocks a new environment for diamond formation diamonds commonly occur in kimberlites lamproites and alluvial sediments derived from these rocks more recently diamonds or their graphite pseudomorphs have been discovered in ultramafic massifs1 and picrites2 here we report the occurrence of diamonds in situ in crustal rocks highly retrograded high pressure metamorphic garnet pyroxene and pyroxene carbonate garnet rocks biotite gneisses and schists from the kokchetav massif northern kazakhstan ussr the diamonds are cubo octahedral averaging 12 m in size and occur in zircons and with euhedral graphite as inclusions in unzoned garnets we believe that the zircon and garnet matrices protected these diamonds from retrogressive transformation to graphite mica rutile titanite clinopyroxene kyanite and zircon also occur as inclusions in garnet often intergrown with the diamonds equilibration relations of inclusions and host garnets indicate that both diamonds and graphite crystallized from a fluid phase under static conditions at pressures of 40 kbar and temperatures 900 1 000 c

monitoring rapid head scarp movement in an alpine rockslide abstract the aresawa rockslide in the japanese alps which partially collapsed in may 2004 produced a number of new tension cracks in the head area this paper discusses the dynamics of the rock slope and controls on the surface velocity based on the results of on site monitoring of the surface movement and meteorological parameters air and ground surface temperatures precipitation and snow depth the rock mass deformation progressed at ca 60 cm yr 1 mainly along a slip plane dipping downslope at ca 50 the surface velocity of the slipping rock mass showed a significant seasonal variation in response to the water infiltration the velocity was small 1 mm day 1 in winter subzero air temperatures and a heat insulating snow cover and resulting growth of seasonal frost prevent water infiltration into the bedrock and contribute to the rock slope stability most of the movement in this period is attributed to gravitational deformation originating from the overburden pressure in contrast the surface velocity increased up to 10 mm day 1 during snow melting and snow free periods snowmelt and rainfalls promote water infiltration into the bedrock destabilizing the rock slope and accelerating the rock slip such a rapid movement is attributed to water induced sliding superimposed on gravitational deformation

internal structure and deformation of an unstable crystalline rock mass above randa switzerland part ii three dimensional deformation patterns the monitoring of slope displacements over time provides the basis for most rockslide early warning systems yet the prediction of catastrophic failure from these records is highly problematic and tenuous especially if the underlying kinematics and instability mechanism are poorly understood an example is the moving slope above the town of randa in the swiss alps this slope is considered typical of those in crystalline rock that lacks a natural highly persistent weakness plane dipping towards the valley that can serve as a through going detachment surface for kinematic release in part i the companion paper to this the findings from a comprehensive geological and geophysical investigation to image the internal structures of the unstable rock mass were presented in this paper we develop a kinematic model that describes the pattern of displacement vectors for the rock mass along these structures both on surface and at depth the displacements were estimated from 5 years of data from an extensive monitoring system which included surface geodetic and crackmeter measurements borehole inclinometer and extensometer measurements up to 120 m depth and microseismicity the results showed that the displacement field is highly heterogeneous internal deformation is accommodated by both shear and opening mode dislocation of faults and fracture zones which dip moderately to steeply into the slope microseismicity is most intense near the front of the scarp where surface translation in large part reflects the toppling of blocks accommodated by slip along the steeper dipping fractures the small displacement rates at the study site of up to 2 cm year coupled with a modest deviation of up to 15 from vertical of the boreholes posed severe problems for the estimation of horizontal displacements from the inclinometer data we describe the error analysis of these data in some detail since it is relevant for similar installations elsewhere conclusions drawn from this work highlight the importance of integrating various types of data in order to better understand the complex block kinematic processes whose evolution governs the long term progressive failure of unstable rock slopes